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Fuel use efficiency system for a vehicle for assisting the driver to

1. 6 092 021 13 TABLE 5 continued TFuela he value of the geometrically averaged total trip fuel TFuela is initialized to zero when a new trip is inaugurated The initial startup value of TFuela is zero he maximum ramp rate of the throttle position percent per second which is allowable before throttle movement is considered for inefficient use of fuel TLim is stored as a constant in memory he minimum throttle position in percent which is allowed before excess or inefficient fuel is accumulated Tmin is stored as a constant in memory he total excess or inefficient fuel used from the start of he trip Xces is initialized to zero when a new trip is inaugurated The initial startup value of Xces is zero he value of the geometrically averaged total excess or inefficient fuel used from the start of the trip Xcesa initialized to zero when a new trip is inaugurated The initial startup value of Xcesa is zero TLim Tmin Xces Xcesa The nine sub modules which make up the Excess module are Parameters Speed RPM Idling Braking Accelerating Throttle Total Display and Average The Parameters Sub module The Parameters module converts the data from selected elements in the PID array to information used throughout the Excess module FIG 8 is a block diagram summarizing the inputs and outputs of the parameters module 180 As shown the parameters module reads selected vehic
2. RESET PARAMETER 460 Bee DETERMINE WHICH DRIVING 444 462 TYPE IS CONSUMING THE MOST EXCESS FUEL UPDATE FILTERED FUEL ASSIGN DISPLAY UPDATE FILTERED VARIABLE THROTTLE POSITION 466 UPDATE AVERAGE SPECIFIC FUEL CONSUMED o y 6 092 021 1 FUEL USE EFFICIENCY SYSTEM FORA VEHICLE FOR ASSISTING THE DRIVER TO IMPROVE FUEL ECONOMY TECHNICAL FIELD The invention relates to a fuel efficiency indicator in a vehicle and more specifically relates to a system for dynamically detecting inefficient driving actions and indi cating information about excess fuel consumption to the driver BACKGROUND OF THE INVENTION With rising fuel costs an important design goal of vehicle information systems is to provide drivers and especially drivers of long haul trucks with information about fuel economy during operation of the vehicle Many vehicles display a measure of fuel economy such as the gas mileage in miles per gallon While this information is helpful it does not give the driver specific feedback on how specific driving actions impact fuel economy In addition it fails to provide a measure of excess fuel consumption due to specific types of driving actions Drivers are less likely to get information that can help them improve fuel economy from these fuel economy measures and thus are more likely to ignore them Modern motor vehicles are typically equipped with a variety of onboard computers for m
3. trol units coupled to it Electronic control units generate a digital signal on the data link by applying a voltage differ ential between the two wires in the cable A voltage differ ential above a specified threshold represents a logic high value while a voltage threshold below a specified threshold represents a logic low value This type of data link is particularly advantageous for hostile environments because the signal is more robust and impervious to signal degrada tion However other alternative communication media could be used in place of the J1708 cable The ECUs connected on the network communicate with each other according to protocols defined in SAE J1708 and SAE J1587 The SAE J1587 standard is entitled Joint SAE TMC Electronic Data Interchange Between Micro computer Systems and Heavy Duty Vehicle Applications This standard defines one format for data and messages communicated among microprocessors connected to a shared data link and is specifically adapted for use with SAE J1708 According to SAE J1708 J1587 the ECUs on the data link communicate by passing messages to each other The ECUs can be either receivers or receivers and transmitters In this particular implementation the instrumentation control unit and the engine ECU are both transmitters and receivers For the purpose of monitoring vehicle performance data the engine ECU acts as a transmitter sending messages to the ICU regarding road speed fuel rate
4. BRAKE 1 MAINTAIN CURRENT DATA IN PENDING STATE TRANSFER K E IN PENDING STATE TO CONFIRMED STATE RESET BASp AND BRSp r a 902 FIG 12A U S Patent Jul 18 2000 Sheet 10 of 13 6 092 021 2A FIG 12B Se Soe ae ee ee CC amp BRSC MPH BASC 9 334 TP Tmin CALCULATE EXCESS BRAKED BRSC MPH amp NO FUEL CONSUMED USING eqn 1 CALCULATE EXCESS BRAKED FUEL CONSUMED USING ean 2 340 338 BFuel NO gt FPI YES 342 344 U S Patent Jul 18 2000 Sheet 11 of 13 6 092 021 354 NO BRAKES amp BRAKE BAI TP lt Tmin RAt RAt 0 2 358 362 NO 366 BASC 0 364 YES BASC BASC 376 BRSC BRSM YES Et Et 0 2 380 BAIZBRAKEP 99 CRETURND FIG 12C U S Patent Jul 18 2000 Sheet 12 of 13 6 092 021 is Y FIG 13 CURRENT SFC gt SFCa REFERENCE amp MPH gt LSLIm 402 YES CALCULATE INCREASE IN SPECIFIC FUEL CONSUMPTION 404 YES CALCULATE RATE OF CHANGE IN THROTTLE U S Patent Jul 18 2000 Sheet 13 of 13 6 092 021 FIG 14 lt START gt ACCUMULATE ACTUAL FUEL CONSUMED ACCUMULATE EXCESS FUEL DURING CURRENT INTERVAL UPDATE TOTAL EXCESS FUEL ACCUMULATE EXCESS FUEL CONSUMED FOR EACH SOURCE 420 422 424 426 442
5. engine torque RPM throttle position engine status etc In this format a message includes the following 1 a module ID MID 2 one or more parameters the message data and 3 a checksum The number of parameters in a message is limited by the total message length defined in the SAE J1708 standard The message identification numbers are assigned to transmitter categories as identified in SAE J1587 The MID portion of a message specifies the origin or transmitter of the message In the majority of cases mes sages are broadcast on the data link without specifying a receiver However the message format can be extended to include the MID of a receiver after the MID of the trans mitter for special applications The messages passed among the ECUs convey information about one or more parameters contained within the mes sages According to the SAE J1587 standard the first character of every parameter is a parameter identification character PID The parameter identified by the PID directly follows the PID The SAE J1587 supports different data formats including a single character a double data character or more than two data characters representing the parameter data Several parameters can be packed into a message limited by the maximum message size as noted above Again in this implementation the ECUs communicate with each other over the data link according to the SAE standard J1708 The standard describes methods for accessing the
6. equation Beta Beta 0 0001 DV Dg Note that the drag factor is computed incrementally based on its previous value and whether the vehicle speed and grade are increasing or decreasing The Excess Module One implementation of the Excess Module is composed of nine sub modules which operate iteratively to identify unnecessary or inefficient fuel use if any Unless otherwise stated information from the prior iterations is read from memory as an input at power on updated by one or more of the sub modules and stored in memory when the system is powered down Execution of all of these sub modules is triggered when the fuel rate PID 183 information is updated five times per second The sub modules within the Excess module utilize the following inputs TABLE 5 the accumulated fuel in gallons used from the start of the trip due to operating the vehicle at speeds above a predetermined speed SLim AFuel is initialized to zero when a new trip is inaugurated The initial startup value of AFuel is zero a brake application indicator which is set equal to one to show that an initial braked speed has been recorded BAI is updated by a Braking Accelerating sub module and initialized to zero when a new trip is inaugurated The initial startup value of BAI is zero the confirmed brake application speed It is calculated such that the difference in the vehicle s kinetic energies between BASc and BRSc see below represents the accumulated brak
7. the system monitors several ineffi cient driving conditions including excessive speed leading to increased aerodynamic drag high engine RPM excessive idling frequent braking and accelerating and rapid throttle movement During operation of the vehicle the system dynamically determines whether these inefficient driving conditions are present In evaluating the vehicle perfor mance data the system evaluates performance parameters to distinguish between inefficient and normal driving actions When inefficient driving is detected the system computes a measure of excess fuel consumed due to the inefficient driving action 10 15 20 25 30 35 45 50 55 60 65 2 This embodiment includes an output device namely a display device to indicate a measure of the excess fuel consumed due to a detected condition that has caused the vehicle to consume excess fuel It also uses the output device to provide the driver with prompting messages indicating the cause of the excess fuel consumption and a driver action that can be taken to reduce excess fuel consumption For example in response to detecting excess fuel consumption due to braking and accelerating the display prompts the driver with a text message stating Drive Steady Speed Other types of output devices can be used to convey this information to the driver such as an audio speaker to provide the information aurally Further advantages and features of the
8. 1 Otherwise it sets the brake application indicator low i e BAI 0 BFuel This section of the module calculates the excess fuel if any consumed during the current iteration due to unnecessary braking accelerating 6 092 021 19 The first step 330 is to determine if the throttle position is greater than the minimum throttle position and the vehicle speed is between the confirmed brake release speed and the confirmed brake application speed BRSc lt MPH lt BASc If it is then the BFuel Section 304 calculates the increment of excess braked fuel BFuel consumed using the following equation equation 1 332 BFuel GVW MPH2 BRSc2 SFCa DTett 274292480 If the throttle position is greater than the minimum throttle position PT gt Tmin and the confirmed brake release speed is less than the current vehicle speed but the confirmed brake application speed is less than the current vehicle speed BRSc lt MPH and BASc MPH 334 then it calculates the increment of excess braked fuel BFuel consumed using the following equation equation 2 336 BFuel GVW BASc 2 BRSc 2 SFCa DTett 274292480 Otherwise it sets the increment of excess braked fuel equal to zero 338 If the braked fuel exceeds the actual fuel BFuel gt FPI 340 then the BFuel section sets the value of the braked fuel BFuel equal to the fuel per iteration FPI i e BFuel FPI 342 Otherwise it sets BFuel BFuel 344 Updates This the last
9. 55 60 65 26 In the third step if PCase equals 2 the previous case represents excessive idling and DCase equals zero then the display driver sets PCase equal to zero This step ensures that the prompting message for excessive idling is turned off when the excessive idling condition is no longer present Otherwise if DCase equals 3 meaning that the speeding condition was detected then the display driver sets PCase equal to 3 If DCase does not equal 3 then it sets PCase equal to its current value In the fourth step if PCase equals 1 meaning that the breaking accelerating condition was detected in the last iteration and DTime is greater than 30000 30 seconds then the display driver sets PCase equal to minus one Otherwise it sets PCase equal to its current value In the fifth and last step if PCase equals minus one and DTime is greater than 300000 and less than 315000 then the display driver sets PCase equal to one Otherwise it sets PCase equal to its current value Next the display driver determines the message set to be displayed in the driver information center based on the message set parameter The display driver then determines whether to increment the elapsed time parameter Dtime Note that the elapsed time parameter is used to evaluate the case where the breaking accelerating condition is present for more than 30 seconds If the vehicle speed is increasing then the elapsed time parameter is not incremented
10. However if the vehicle speed is not increasing and a prompting condi tions was detected in the last iteration then the elapsed time parameter is incremented by a constant representing the elapsed time since the last iteration e g 200 ms Part 2 of the display driver retrieves from memory and inserts current numeric values if needed into the prepro grammed message selected for display Next if fuel ineffi cient driving is occurring and driver prompting messages are enabled the normal driving message is replaced by a driver prompting message Using the keypad specific messages within the general fuel efficiency and message sets can be selected for display If enabled the driver prompting messages appear whenever fuel inefficient driving is detected A number of examples of the general fuel efficiency messages are described below Examples of General Fuel Efficiency Messages MPG Bargraph with FUEL SCORE The following table shows the format of this message on the 2 line display xxx MPG XXX Bargraph FUEL SCORE The bargraph is implemented using the characters on the vacuum flourescent display device The maximum length of the bar displayed is 13 characters The actual length of the bar displayed is 13 19 9 STAFE The MPG value displayed is the value of STAFE If the parameter TFuel is greater than zero the FUEL SCORE value displayed is determined as follows FUEL SCORE 1 3 Xces TFuel 100 If TFuel is not greater
11. also includes a variety of sensors and controls used to monitor and control the engine In this implementation the engine ECU controls the fuel rate by issuing control signals to a fuel injector 48 that controls the flow of fuel to the engine s cylinders This implementation of the ECU includes several sensors that monitor vehicle performance including a speed sensor 50 an RPM sensor 52 a throttle position sensor 56 and a cruise status sensor 58 Some vehicle performance parameters are computed from measured data For example the engine torque is computed as a function of measured parameters including fuel rate and turbo boost pressure The engine ECU controls the fuel rate and serves as a fuel rate measuring device for the system It compares the throttle position to the percent engine load If their is a difference then the engine ECU changes the dwell time of the fuel injector increases or decreases the fuel injected into the cylinder Before the engine ECU applies the dwell to the fuel injector it processes the dwell time further to limit emissions The emission control computation can modify the injection timing and dwell In this implementation the engine ECU determines the amount of fuel supplied to the cylinders in the engine by controlling the solenoid valves that inject fuel to the engine cylinders The rate of fuel flow is directly related to the amount of time that the solenoid valve is closed This time period determines
12. by the speed time criteria This speed is identified as the con 6 092 021 17 firmed Brake Release Speed BRSc In addition a second higher speed identified as the confirmed Brake Application Speed BASc is computed and stored The value of BASc is calculated such that the difference in the vehicle s kinetic energy between these two speeds represents the accumulated braked change in the vehicle s kinetic energy This accumu lated braked change in kinetic energy represents the poten tial increase in fuel consumption The change in kinetic energy due to braking the vehicle is converted to an equiva lent quantity of fuel as the vehicle s speed increases from BRSc to BASc unless the following conditions are met 1 the vehicle s speed drops below the low speed limit LSLim or 2 the throttle application is less than Tmin percent or does not increase the vehicle s speed above the speed time criteria defined by recursively modifying the con firmed brake release speed BRSc using the equation BRSc BRSc exp 0 0002 E where Et is the time in seconds since the brakes were released To evaluate the second condition the ICU monitors the speed increase rate after the driver applies the brakes If the driver accelerates faster than a predetermined rate then the ICU proceeds to evaluate whether excess fuel is being consumed due to rapid acceleration after a brake event The pending state stores the most recent braked change
13. not idling 274 If the engine is idling and the current idle timer is greater than the idle time limit Idling 1 and Itime gt ILim 276 then the idling module adds the current increment of fuel to the fuel consumed idling as shown in Step 278 i e IFuel IFuel FPI Otherwise it sets IFuel IFuel The last step 280 is to increment the cumulative and current idle timers by 200 ms if the engine is idling Idling 1 ie ITime ITime 0 2 Otherwise it leaves the idling time unchanged for the current iteration ITime ITime The Braking Accelerating Sub Module The Braking Accelerating sub module calculates the change in the vehicle s speed kinetic energy while braking and the elapsed time between braking accelerating events to determine if the braking resulted in increased fuel consump tion Braking is considered necessary if any of the following rules are true Braking reduces the vehicles speed below the Low Speed Limit LSLim an input The time between release of the throttle and application of the brakes or release of the brakes and application of the throttle Release Application time RAt exceeds the Throttle Brake time TBt an input In this implementation information about braked changes in the vehicle s kinetic energy is stored in two states pending and confirmed The confirmed state stores the speed at which the vehicle s brakes were last released which produced a confirmed loss of kinetic energy modified
14. or inefficient fuel used during the current interval is the sum of the excess fuels from each of the sources 422 i e FLoss AFuel RFuel BFuel MFuel If FLoss is larger than FPI then it sets FLoss FPI Otherwise it sets FLoss FLoss The total module then updates the excess fuel 424 using Xces Xcest F Loss The accumulated inefficient fuel consumed by each of the sources is updated 426 as follows 10 15 20 25 30 35 40 45 50 55 60 65 22 AFuel 4Fuelp 4 Fuel BFuel BFuelp BFuel JFuel Fuelp Fuel MFuel MFuelp Mfuel and RFuel RFuelp RFuel where the lower case p designates the previous value from memory The Display Sub module The display sub module selects which if any of the fuel inefficient driving types is currently producing the largest increment of excess fuel FIG 15 illustrates a flow diagram illustrating an overview of the steps performed the display module In some special cases this module is responsible for disabling the message prompt For example to avoid dis playing a SHIFT UP SAVE FUEL message if the vehicle speed is greater than the current vehicle speed MPH gt SLim then it sets RFuel 0 442 Otherwise it sets RFuel RFuel The next step 444 is to determine which of the driving types is producing the largest increment of excess fuel if any and assign the variable DCase the numeric value shown in Table 5 446 TABLE 6 Driving Type Exc
15. than zero then the display driver sets FUEL SCORE equal to 100 Alternatively if this value of FUEL SCORE is less than 30 then FUEL SCORE is set equal to 30 6 092 021 27 Efficiency Bargraph with Trip Efficiency The following table shows the format of this message on the 2 line display Xxx xx x Bargraph Trip The maximum length of the bar displayed is 16 charac ters The actual length of the bar displayed is 0 16 eff The value displayed to the right of the bar is the value of eff If TFuel is greater than 0 1 the TRIP is computed as follows TRIP 1 3 Xces TFuel 100 If TFuel is not greater than 0 1 then the display driver sets TRIP 46 equal 100 Alternatively if this value of TRIP is less than 50 then it recalculates TRIP as follows TRIP 1 2 Xces TFuel 100 Fuel Efficiency with Trip Efficiency The following table shows the format of this message on the 2 line display Xxx XX X Fuel Efficiency Trip The FUEL EFFICIENCY value displayed is the value of eff If TFuel is greater than 0 1 the TRIP displayed is determined as follows TRIP 1 3 Xces TFuel 100 If TFuel is not greater than O 1 then the display driver sets TRIP equal to 100 Alternatively if this value of TRIP is less than 50 then it recalculates TRIP 46 as follows TRIP 1 2 Xces TFuel 100 Prompting Messages In this implementation there are five specific prompting messages as shown in Table 3 abov
16. the message parameters in response to inputs from the keypad The display driver begins by evaluating whether to update the message set and subset parameters Next part 1 of the display driver determines whether to enable a driver prompting message Determining the driver prompting message if any is a five step process This process is computed based on the following parameters 1 Dcase This is the number of the case to be shown on the display as determined in the Excess module 2 Pcase This is the value of the case previously shown on the display 3 Dmin This is the minimum time in milliseconds that a message is displayed The value of this parameter can be entered as an input to the ICU 4 DTime This is the number of milliseconds that the current prompting message has been displayed This parameter is updated and stored in memory for every iteration of the display driver module Step one of the process is to take the absolute value of the parameter PCase from the previous iteration In the second step if PCase is greater than zero and the display time DTime is less than the minimum display time Dmin and DCase equals zero then the display driver sets PCase equal to its previous value This ensures that a prompting message will be displayed for at least the minimum display time If the conditions of step two are not met then the display driver sets PCase equal to DCase 10 15 20 25 30 40 45 50
17. the VPE module The initial startup value of Gr is zero he aerodynamic drag factor which is iteratively estimated and updated by the VPE module The initial startup value of Beta is 0 085 he mechanical efficiency of the drivetrain It is stored as a constant in memory he sum of the longitudinal force driving the vehicle during each of the n iterations The initial startup value of FSum is zero he estimated gross weight of the vehicle he average parasitic engine horsepower loss excluding he engine cooling fan hpL is stored as a constant in memory n a counter which records the number of iterations seconds of summing and updating of data Its initial startup value is zero a 256 element data array which contains the most recent information from the J1587 1708 data bus for MID 128 Engine PID is updated by the INPUT module r the rolling resistance coefficient of the vehicle It is Stored as a constant in memory the sum of the squares of the vehicles velocity during each of the n iterations The initial startup value of V 2Sum is zero the sum of the vehicles velocity during each of the n iterations The initial startup value of VSum is zero the vehicles velocity at the start of the summing process The initial startup value of Vo is zero Beta DTeff FSum GCW hpL PID V 2Sum VSum Vo Vehicle Parameter Estimation or VPE includes two parts The first part Part 1 uses information from th
18. to identify the message and the size of the parameters in the message single byte or multi byte data and temporarily stores the parameters in memory of the ICU The parser then verifies that the data is valid by evaluating the checksum If the data is valid it updates the PID array with the parameters from the message At power on all values in the PID array are set to zero This module is executed as frequently as possible to insure that the most current information from the engine control unit is available for use by the other software modules Flags are set whenever updated engine torque PID 93 once per second fuel rate PID 183 five times per second or RPM PID 190 ten times per second messages are received The Vehicle Parameter Estimation Model The VPE module 122 utilizes the information generated by the INPUT module to estimates the vehicle s weight GCW aerodynamic drag factor Beta and the gradient Grade of the roadway Unless otherwise stated informa tion from the prior iterations is read from memory as an input at power on and updated and stored in memory when the system is powered down This module is executed once per second when the engine torque PID 93 information is updated and recorded in memory for use by the other modules VPE utilizes the following inputs defined in Table 4 6 092 021 9 TABLE 4 VARIABLE DEFINITION GR he gradient of the roadway which is iteratively estimated and updated by
19. OOTH UPDATE THE 172 DRAG FACTOR U S Patent Jul 18 2000 Sheet 5 of 13 6 092 021 CRUISE VEHICLE NOT BEING RETARDED amp HP EXCEEDS THRESHOLD U S Patent Jul 18 2000 Sheet 6 of 13 6 092 021 208 DIFFERENCE BETWEEN CURRENT SPEED AND Sa EXCEED LIMIT YES 210 INCREMENT DECREMENT CURRENT SPEED LIMIT FIG 9B CALCULATE INCREMENTAL HORSEPOWER REQUIRED TO OPERATE VEHICLE AT SPEEDS EXCEEDING SLIM COMPUTE EXCESS 226 FUEL CONSUMED EXCESS FUEL FPI EXCESS DUE TO INCREASED DRAG FUELO U S Patent Jul 18 2000 Sheet 7 of 13 6 092 021 START RPM COMPUTE CURRENT E ENGINE SPEED LIMIT ESL CALCULATE AND COMPARE CURRENT RATIO OF VEHICLE SPEED TO ENGINE SPEED L 242 WITH PREVIOUS RATIO FIG 10 RATIOS 244 WITHIN LIMIT amp a MPH LSLim TP min OR 248 SET RSI 246 TOZERO CALCULATE INEFFICIENT FUEL USED FOR EXCESS RPM 250 U S Patent Jul 18 2000 Sheet 8 of 13 6 092 021 START IDLING CALC 270 NO FIG 11 274 NOT IDLING SET IDLING PARAMETER CURRENT IDLE TIMER gt LIM ADD CURRENT INCREMENT OF FUEL TO THE INEFFICIENT FUEL CONSUMED INCREMENT CUMULATIVE AND CURRENT IDLE TIMERS U S Patent Jul 18 2000 Sheet 9 of 13 6 092 021 START BRAKING ACCELERATING MODULE 310 BASp gt 0 MPH gt LSLim RAt gt TBt TP gt Tmin or 2
20. Systems in Heavy Duty Vehicle Applica 119 A 340 439 325 06 462 870 16 436 lions 1988 870 13 461 123 478 480 477 100 42 Primary Examiner Jacques H Louis Jacques 43 107 Attorney Agent or Firm Klarquist Sparkman Campbell Leigh amp Whinston LLP 56 References Cited ii 57 ABSTRACT U S PATENT DOCUMENTS 3 605245 10 1972 Ishida 123 444 cine aed ee id display system for a vehicle 325 753 12 1975 Auman et al 340 439 ynamically evaluates vehicle performance parameters to 4 157 030 6 1979 Keely s 73 113 detect conditions that cause excessive fuel consumption 4 241 751 1 1981 Crump Jr 73414 The conditions include increased aerodynamic drag due to 4 258 421 3 1981 Juhasz et al 701 35 excessive speed high RPM braking and accelerating 4 384 479 5 1983 Handtmann 73 114 excessive idling and rapid throttle movements The system 4 400 779 8 1983 Kosuge et al 701 123 dynamically estimates gross vehicle weight roadway grade 4 475 380 10 1984 Colovas et al 73A14 and drag factor from monitored parameters and uses these a 3 i Eis iem VON DRM A UU d estimates to detect inefficient fuel use The system indicates ie Toa p Si ali to the driver when inefficient fuel use is detected For d cae dice ERU rx BA d example it displays a measure of excess fuel consumed and 4 570226 2 1986 Aussedat 701 123 messages indicating actions that can be taken to improve 4 630 027 12 1986 Muhlberg
21. US006092021A United States Patent pn 1 Patent Number 6 092 021 Ehlbeck et al 4 Date of Patent Jul 18 2000 54 FUEL USE EFFICIENCY SYSTEM FOR A 4 747 301 5 1988 Bellanger 0 0 0 7317 3 VEHICLE FOR ASSISTING THE DRIVER TO 4 845 630 7 1989 Stephens comics 701 123 IMPROVE FUEL ECONOMY 4 945 759 8 1990 Krofchalk et al wee 73 1173 5 017 916 5 1991 Londt et al ve 340 870 13 75 Inventors James M Ehlbeck LaCenter Wash es lod pee et al see bo Goetz Renner Esslingen Germany 5 173 856 12 1992 Purnell et al 2 701 35 Jared A Powell Christopher L Kirn 5 303 163 4 1994 Ebaugh et al 340 439 both of Portland Oreg 5 652 378 7 1997 Dussault we 73 114 5 693 876 12 1997 Ghitea Jr st 73 114 73 Assignee Freightliner Corporation Portland Oreg OTHER PUBLICATIONS Cadec Celect RoadRelay User s Guide Cadec Systems 21 Appl No 08 982 117 Inc Londonderry NH Cummins Electric 1993 AM Flyer Detroit Diesel ProDriver User Manual 1994 22 Filed Dec 15 1397 Operating and Error Codes Series 925 205 FloScan Instru 51 Int o AMAIA G06G 7 70 GO1L 3 26 ment Company Inc Seattle WA 4 93 BIUS AA 701 123 701 29 73 113 Caterpillar Owner s Manual Caterpillar Driver Informa 73 114 73 117 3 73 115 tion Display Feb 1995 58 Field of Search sss 701 30 29 123 Joint SAE TMC Electronic Data Interchange Between 701 32 73 113 114 112 116 115 117 3 Microcomputer
22. amic drag 6 092 021 29 8 The method of claim 7 further including dynamically estimating the aerodynamic drag factor of the vehicle 9 The method of claim 7 further including indicating the excess fuel consumed due to increased aerodynamic drag to the driver 10 The method of claim 1 wherein the condition com prises high engine RPM 11 The method of claim 10 wherein the high engine RPM condition is detected by comparing current RPM of the vehicle with a reference RPM that is dependent on a dynamically determined horsepower of the vehicle 12 The method of claim 10 wherein the step of detecting the high engine RPM condition includes determining whether the driver is shifting the vehicle during a predetermined monitoring period when it is determined that the driver is shifting during the predetermined monitoring period determining that the high engine RPM condition is not satisfied to avoid indicating that excessive fuel is being consumed due to high engine RPM 13 The method of claim 10 further including computing excess fuel consumed due to high engine RPM 14 The method of claim 13 wherein the excess fuel consumed is proportional to an amount by which current engine RPM exceeds a calculated engine speed limit 15 The method of claim 13 further including indicating the excess fuel consumed due to high engine RPM to the driver during operation of the vehicle 16 The method of claim 1 wherein the condi
23. ated fuel in gallons used from the start of the trip due to operating the engine at speeds greater than the engine speed limit RFuel is initialized to zero when a new trip is inaugurated The initial startup value of RFuel is zero the minimum engine speed in RPM above which increased engine speed is considered as inefficient use of fuel RLim is stored as a constant in memory To accommodate various engine speed ratings its value should be initialized based on information from the engine ECU at power on the short term average vehicle speed in miles per hour for vehicle speeds greater than 55 and less than 75 mph The initial start up value of Sa is 55 the geometric average or initial specific fuel consumption of the engine in gallons per horsepower hour SFCa is initialized to 0 05 when a new trip is inaugurated The initial startup value of SFCa is 0 05 the maximum speed in MPH which the vehicle can be operated before it is considered to be speeding SLim is an input which can be varied as the program is operating the maximum time in seconds between release of the brakes and application of the throttle or release of the throttle and application of the brakes for these release applications to be considered as inefficient use of fuel TBt is stored as a constant in memory the total fuel in gallons used from the start of the trip TFuel is initialized to zero when a new trip is inaugurated The initial startup value of TFuel is zero
24. ated gross weight is calculated using the following equa tion 166 GW GW p e GW V Vo 32 2 r In this implementation the gross weight is computed incrementally based on the previous value of the gross weight the gain factor which depends on whether the vehicle is sustaining high acceleration and torque the estimated velocity and the rolling resistance Next the estimated percent roadway grade gr is calcu lated using the following equation 168 gr 100 FSum Beta V 2Sum n GCW a r The variations in the estimated value of the roadway grade are smoothed using the following equation 170 Gr 0 8 Gr 0 2 gr Finally the VPE module updates the drag factor as shown in step 172 If the absolute value of the variation in the vehicle s velocity is greater than 0 5 abs V VSum n 0 5 then the VPE module uses the following equation to deter mine if the estimated grade increased or decreased Dg sign Gr gr otherwise set Dg 0 The sign function returns the value 1 0 or 1 if the value of the argument Gr gr is greater than equal to or less than 6 092 021 11 zero respectively If the vehicle is operating at a sustained velocity greater than 70 with a low acceleration V gt 70 amp abs a lt 0 011 then the VPE module uses the following equation to determine if the vehicles velocity is increasing or decreasing DV sign V VSum n otherwise set DV 0 The VPE module then estimates the drag factor using the
25. d condition within a predefined period of detecting the condition and a cause of the detected condition 46 The method of claim 45 wherein the predefined period is less than a second 47 The method of claim 45 wherein the predefined period is less than 300 milliseconds 48 The method of claim 45 wherein the indicating step includes displaying a prompting message indicating the type of condition to the driver 10 15 20 25 30 32 49 The method of claim 48 further including displaying an indicator of a quantity of excess fuel or fuel efficiency loss due to the detected condition 50 The method of claim 45 wherein the condition includes one or more of the following increased aerodynamic drag due to excessive vehicle speed operating at high RPM excessive idling changes in kinetic energy due to braking or accelerating or rapid throttle movement 51 The method of claim 45 wherein the detecting step includes monitoring for two or more of the following conditions increased aerodynamic drag due to excessive vehicle speed operating at high RPM excessive idling changes in kinetic energy due to braking or accelerating or rapid throttle movement 52 The method of claim 51 further including determin ing which of the two or more conditions has caused the most inefficient fuel use wherein the indicating step includes indicating the condition that has caused the most inefficient fuel use 53 The method of claim 52
26. data link and constructing messages for transfer over it It also defines a method for resource contention among the ECUs on the data link An ECU wishing to transmit data on the data link first waits for a lull in transmission of data on the data link In this particular implementation the length of the lull is 200 milliseconds After detecting this lull the ECU attempts to transmit its message The transmitter broadcasts its message onto the data link Each of the ECUs that operate as receivers on the data link will receive the message However receiv ers only act on a message if programmed to do so 5 10 15 20 25 30 35 40 45 50 55 60 65 6 In some cases two or more transmitters may attempt to broadcast a message at one time giving rise to a collision To resolve a conflict among transmitters messages have a priority according to their message identifiers The MIDs of higher priority transmitters have a greater number of bits set at a logic level one When more than one message is broadcast at a time the more dominant message takes priority over lesser dominant messages Since a lower pri ority message is blocked by a higher priority message the transmitter of the lower priority message must wait and retransmit the message after another lull An ECU on the data link will continue to attempt to send a message until it is successfully broadcast to the data link As introduced above the ICU obtains
27. driver consists of two parts Part 1 combines information from the previous modules and the previous iteration with current inputs from the driver keypad to determine if the information displayed in the driver message center requires updating Part 1 directs Part 2 to a maintain the current message in the driver message center b update the driver selected prepro grammed normal driving message or c if enabled display one of the preprogrammed driver prompting messages Part 1 determines which message to display and when to update the display In this implementation the messages are grouped in three sets 1 general fuel efficiency messages 2 trip summary related messages and 3 prompting messages Each of these message sets is associated with a message set parameter The driver can control the value of the message set parameter by operating push buttons on the key pad of the ICU The first message set also includes a number of fuel efficiency messages each associated with a message subset parameter The driver can select one of the fuel efficiency messages to display by operating a button on the key pad as well If an inefficient driving condition is detected however the prompting messages take precedence over the driver selected messages or the normal driving messages The first step in the display driver module is to evaluate the parameters that control the current message set and subsets The display driver is responsible for updating
28. e one alternative display format shows the fuel required to efficiently operate the vehicle divided by the actual fuel consumed It also displays the miles per gallon current fuel consumption and an odometer reading The ICU continu ally updates fuel efficiency data and presents messages and values to the driver in real time Whenever the ICU detects fuel inefficient driving it changes the format of the display in FIG 4 to another format such as the one shown in FIG 5 The display 102 in FIG 5 shows a bargraph 110 and a numerical value 112 depicting the magnitude of the improvement in fuel economy that could be gained by taking the action suggested by the text message 114 displayed below it TABLE 3 Driving Type Prompting Message Speeding DRIVE XX MPH Gain x x MPG High Engine RPM SHIFT TO NEXT GEAR Gain x x MPG END IDLING SAVE x xx GAL Hr DRIVE STEADY SPEED Gain x x MPG MOVE THROTTLE SLOWER Excessive Idling Braking Accelerating Rapid Throttle Movement Gain x x MPG One implementation of the fuel efficiency system com prises four software modules executing from memory on the ICU FIG 6 is a block diagram illustrating these modules The following four modules are executed repetitively to compute fuel efficiency data and update the display on the dash of the vehicle 1 INPUT 120 2 VEHICLE PARAM ETER ESTIMATION 122 3 EXCESS 124 and 4 DIS PLAY DRIVER 126 It is important to emphasize that these modul
29. e These messages are identified by PCase values of 1 through 5 Speeding The MPH displayed in the first line of this message is the reference speed Sref The Gain value displayed is Lmpg calculated by the display sub module of the Excess software module High Engine RPM The Gain value displayed is Lmpg calculated by the display sub module of the Excess software module Excessive Idling The SAVE value displayed is the current fuel rate of the engine expressed in GAL Hr i e PID 183 divided by 64 Braking Accelerating The Gain value displayed is Lmpg calculated by the display sub module of the Excess software module Rapid Throttle Movement The MPG displayed in the first line of this message is the reference speed Sref The Gain value displayed is Lmpg calculated by the display sub module of the Excess software module Conclusion While the invention is described with reference to a specific implementation it is important to emphasize that 10 15 20 25 30 35 40 45 50 55 60 65 28 the invention is not limited to the specific design details of this implementation The sensors used to monitor engine parameters need not be connected to the engine ECU but instead can be connected to the control unit that evaluates the data to detect excess fuel use e g the ICU In addition the format of the data does not have to be in the form of serial data from a serial data link as in a system built f
30. e PID array to determine if the operating conditions are correct for updating the parameter estimates The second part Part 2 performs the necessary calculations and updates the param eter estimates if the necessary conditions are met FIGS 7A and 7B are a flow diagram illustrating the operation of both of these parts of the VPE module 122 The reference numbers associated with the steps in the flow diagrams are set forth in parentheses next to the corresponding description in the text below Part 1 of the VPE Module The first part of the VPE module converts the data from selected elements in the PID array to the information used throughout VPE as shown in step 140 FIG 7A In addition Part 1 assigns the value of zero or one to the variable Case which is used as the basis for updating the parameter estimates First it calculates the value of the following variables as defined below also see step 142 FIG 7A Part 1 of the VPE module sets a parameter Brake equal to one if either the brakes are applied bit six of PID 85 is equal to one or the engine retarder is operating bit 8 of PID 121 is equal to one The VPE module computes the vehicle velocity engine torque and horsepower from selected PID values stored in the PID array V vehicle velocity PID 84 0 7335 Torque engine torque PID 93 20 HP horsepower Torque PID 190 21009 hpL The last step of Part 1 is to set Case 1 if all of the following are met decision step 144
31. e minimum throttle position or the cruise is engaged TC 1 but the incremental aerodynamic horsepower is not less than the engine horse power 222 then it sets the inefficient fuel consumed AFuel equal to all the fuel consumed during the current iteration as shown in Step 224 i e AFuel FPI Otherwise it sets AFuel equal to zero The RPM Sub module The RPM sub module calculates the increase in fuel consumption if any due to operating the engine at speeds 6 092 021 15 higher than necessary for operation of the vehicle It employs the heuristic criteria that fuel consumption is reduced by 1 5 per 100 rpm reduction in engine operating speed The RPM module detects special cases where a high RPM is justified and does not compute excess fuel in these cases One special case is for operating the engine at higher speeds to provide additional horsepower for accelerating climbing grades down shifting etc Although empirical these requirements are addressed by simply adding one half the current engine horsepower to the allowable engine speed RLim before computing inefficient fuel consumption Setting the allowed engine speed to 1550 RLim 1550 has provided good results with 1800 rpm engines and 9 10 speed transmissions 30 40 gear steps This method can be generalized to address higher rpm engines 1900 2200 rpm and or other transmissions A second special case is for operating the engine at high speeds when down shift
32. e to excess idling to the driver 10 15 20 25 30 35 40 45 55 65 30 27 The method of claim 1 wherein the condition com prises rapid throttle movement 28 The method of claim 27 further including determining the rate of change of throttle position 29 The method of claim 27 further including comparing specific fuel consumption with an average specific fuel consumption to evaluate whether rapid throttle movement resulted in consumption of excess fuel 30 The method of claim 27 further including computing excess fuel consumed due to rapid throttle movement during operation of the vehicle 31 The method of claim 30 further including indicating excess fuel consumed due to rapid throttle movement to the driver during operation of the vehicle 32 The method of claim 1 further including dynamically estimating vehicle drag and using the estimated vehicle drag to detect when changes in vehicle speed result in excess fuel consumption 33 The method of claim 32 further including dynamically estimating grade of the roadway 34 A computer readable medium having instructions for performing the steps of claim 1 35 A fuel efficiency indicator for a vehicle comprising an output device and an instrumentation control for receiving vehicle perfor mance parameters monitored during operation of the vehicle for detecting from the vehicle performance data whether a condition exists in which the veh
33. easuring and recording vehicle performance and diagnostic data These devices provide a great deal of information about the performance of the vehicle during operation The problem is not lack of information but rather evaluating it and conveying it to the driver in a useful fashion There is a need for a fuel efficiency indicator that uses this data to assist the driver to operate the vehicle more efficiently and take actions that avoid excess fuel consumption SUMMARY OF THE INVENTION The invention provides a fuel efficiency system and related method that indicate when the driver is operating the vehicle inefficiently This system provides feedback to the driver when the vehicle is consuming excess fuel due to inefficient driving actions It monitors vehicle performance data and dynamically analyzes the data to determine when the driver s actions result in inefficient fuel use When the system detects a condition that cause the vehicle to consume excess fuel it indicates the presence of the condition to the driver In one embodiment of the invention the fuel efficiency system displays a message indicating that fuel inefficient driving has been detected In addition the system also provides the cause of excess fuel use and suggests an action that the driver can take to fuel economy This embodiment also computes the amount of excess fuel consumed due to inefficient driving and displays a measure of it to the driver In this embodiment
34. ed change in the vehicle s kinetic energy BASc is updated by the Braking Accelerating sub module and initialized to zero when a new trip is inaugurated The initial startup value of BASp is zero the vehicle speed in mph when the brakes are applied BASp is updated by the Braking Accelerating sub module and initialized to zero when a new trip is inaugurated The initial startup value of BASp is zero represents the speed at which the vehicle s brakes were last released which produced a confirmed loss of kinetic energy modified by the speed time criteria The Braking Accelerating sub module updates BRSc which is initialized to zero when a new trip is inaugurated The initial startup value of BRSc is zero he vehicle speed in mph when the brakes are released The Braking Accelerating sub module updates BRSp which is initialized to zero when a new trip is inaugurated The initial startup value of BRSp is zero he estimated aerodynamic drag factor an input from VPE module he accumulated fuel in gallons used from the start of he trip due to unnecessary braking accelerating BFuel is initialized to zero when a new trip is inaugurated The initial startup value of BFuel is zero indicates when the vehicle is being retarded Brake 1 by either the service brakes or engine retarder It is updated each iteration by combining logical OR the status of service brakes bit 6 of PID 85 and the engine retarder bit 8 of PID 121 indicates wh
35. en the vehicle is operating in cruise control Cruise 1 It is updated each iteration based of the value of bit 8 of PID 85 If bit 8 is set to one then the ICU sets Cruise to one AFuel BAI BASc BASp BRSc BRSp Beta BFuel Brake Cruise 10 15 20 25 30 35 40 45 50 55 60 65 DTeff Et FPI GVW Fuel ILim ITime Itime LSLim MFuel Over PID RFuel RLim Sa SFCa SLim TFuel 12 TABLE 5 continued the mechanical efficiency of the drivetrain DTeff is stored as a constant in memory the time in seconds since the brakes were last released Et is initialized to zero when a new trip is inaugurated The initial startup value of Et is zero the fuel per iteration It is updated each iteration by dividing the fuel rate PID 183 by 1152000 which provides the gallons of fuel consumed for each 200 ms interval the estimated gross vehicle weight an input from the VPE module the accumulated fuel in gallons used from the start of the trip due to idling the vehicle for periods longer than the idle time limit Fuel is initialized to zero when a new trip is inaugurated The initial startup value of Fuel is zero the maximum time in seconds which the engine can idle before engine idling is considered as inefficient use of fuel Lim is stored as a constant in memory the accumulated time in seconds which the engine ha
36. er et al 701 30 fuel economy in response to detecting inefficient fuel use 4 663 718 5 1987 Augello et al 73 14 4 706 083 11 1987 Baatz et al sss 73 113 54 Claims 13 Drawing Sheets 122 124 126 INPUT MODULE VPE MODULE EXCESS MODULE DISPLAY DRIVER 120 130 DRIVER MESSAGE CENTER SELECTED VEHICLE PERFORMANCE PARAMETERS PARAMETER MODULE CRUISE U S Patent Jul 18 2000 Sheet 1 of 13 6 092 021 FIG 1 INSTRUMENTATION CONTROL UNIT THROTTLE POSITION U S Patent Jul 18 2000 Sheet 2 of 13 6 092 021 FIG 4 104 NORMAL DRIVING MESSAGE 8 4 MPG 191321 7 MI 100 106 108 FIG 5 10 112 LLLLLLELL 0 6 MPGAIN PROMPTING MESSAGE 102 114 ERIAL INPUT MODULE VPE MODULE EXCESS MODULE 130 ANALOG INPUT DATA 122 124 DISPLAY DRIVER MESSAGE pelea CENTER 126 U S Patent Jul 18 2000 Sheet 3 of 13 6 092 021 CONVERT MONITORED _ 140 48 PERFORMANCE DATA E CURIERI CALCULATE V 125 TOR E 146 AND BRAKE STATUS COMPUTE AVERAGE 152 FIG 7A ACCELERATION COMPUTE CURRENT 7 154 TRACTIVE FORCE F 156 COMPUTE DIFFERENCE 458 BETWEEN ACTUAL AND ESTIMATED VELOCITY U S Patent Jul 18 2000 Sheet 4 of 13 6 092 021 164 SET GAIN 162 TO ZERO SET GAIN FOR VEHICLE WEIGHT ESTIMATE BASED ON V ESTIMATE 166 GROSS WEIGHT ESTIMATE 168 ROADWAY GRADE FIG 7B SM
37. es represent one implementation of the inven tion and that the implementation can vary depending on a number of factors such as the type and architecture of the performance monitoring devices in the vehicle the type of vehicle long haul tractor trailer truck business class truck car etc the specific inefficient driving conditions that are monitored etc The Input Module The input module 120 converts serial input data 128 from the serial data bus into an array of asynchronous numeric values which are updated as new messages are received Receipt of selected messages from the engine control unit is used to indicate 100 millisecond 200 millisecond and one second time intervals These time intervals are used to signal the arrival of new data and clock several of the subsequent modules 10 15 25 30 35 40 45 50 55 60 65 8 The Vehicle Parameter Estimation Module The VPE module 122 estimates the vehicles weight GCW aerodynamic drag factor Beta and the gradient Grade of the roadway These estimates are derived from information available from electronically controlled engines plus an analog signal from the engine fan clutch analog input 130 The estimated values are updated once per second and recorded in memory for use by the other mod ules The Excess module The Excess module 124 determines the incremental por tion of the fuel being consumed to operate the vehicle if any attributable to eac
38. ess Fuel DCase No Excess Fuel 0 Speeding AFuel 1 High Engine RPM RFuel 2 Excessive Idling IFuel 3 Braking Accelerating BFuel 4 Rapid Throttle Movement MFuel 5 Excessive idling occurs when the current engine idle time is longer than the idle limit the vehicle speed is zero 2 mph and the PTO is not operating The display sub module is also responsible for updating the mpg for the trip TMPG If the trip fuel TFuel is less than 0 05 then it sets TMPG 0 Otherwise it sets TMPG TODO TFuel Next the mpg loss if any is calculated smoothed and capped If the current vehicle speed is greater than the low speed limit MPH gt LSLim and the fuel consumed during the current iteration is greater than the fuel lost due to monitored inefficient driving conditions FPI FLoss gt 0 then current mpg loss is calculated as follows Lmpg TMPG F Loss FPI F Loss If Lmpg is greater than a constant value e g 5 9 in this case then it is reset capped with Lmpg 5 9 As calculated above the value Lmpg should preferably be smoothed before it can be displayed to drivers This requires carefully selecting values for the filter coefficient K for the geometric filter used to average or smooth Lmpg To provide the smooth operation plus rapid action reaction drivers expect different values of K are needed for various operat 6 092 021 23 ing conditions If the value of Lmpg is greater than its value from the previous iteration Lmp
39. example in the implemen tation described below the current speed limit is dynami cally updated based on the difference between the short term average speed and the current vehicle speed FIGS 9A and 9B show a flow diagram depicting an implementation of the speeding module The first step is to update the current vehicle speed limit using the following adaptive approach Provided that the vehicle is not being 10 15 20 25 30 35 40 45 50 55 60 65 14 retarded Brake 0 and the engine horsepower exceeds 50 HP gt 50 200 the speed module updates the short term average vehicle speed Sa as shown in Step 202 using the following equation Sa 0 99 Sa 0 01 MPH Otherwise it maintains the current value of Sa as shown in Step 204 i e Sa Sa Next the speeding module determines whether the short term average speed is within a predetermined operating range as shown in decision block 206 If the short term average speed is less than 55 mph or greater than 75 mph it sets Sa equal to 55 or 75 respectively 208 The speeding module then determines the variation between the current vehicle speed and the short term average to evaluate whether to update the current speed limit When the variation between the short term average vehicle speed and the current vehicle speed limit exceeds 4 mph positively or negatively i e abs Sa SLim 4 208 the speeding module increments decrements the current vehic
40. for detecting inefficient fuel use due to excessive idling FIGS 12A C are a flow diagram of a braking accelerating sub module in the excess module for detecting inefficient fuel use due to frequent braking and accelerating conditions i e fuel lost due to changes in kinetic energy of the vehicle FIG 13 is a flow diagram of a throttle sub module in the excess module for detecting inefficient fuel use due to rapid throttle movement FIG 14 is a flow diagram of a total sub module in the excess module for accumulating fuel consumption values FIG 15 is a flow diagram of a display sub module in the excess module for determining whether to display a message regarding inefficient fuel use for an inefficient driving action evaluated in the excess module FIG 16 is a flow diagram of an average sub module in the excess module for filtering selected variables DETAILED DESCRIPTION One embodiment of the invention is a fuel efficiency monitoring and display system implemented using elec 6 092 021 3 tronic control units onboard a truck In particular this embodiment includes an instrumentation control unit for detecting and displaying information about inefficient driv ing conditions and one or more control units or discrete sensors for monitoring vehicle performance data The next section describes the system architecture of the electronic control units onboard a vehicle in this embodiment Later sections describe an implementati
41. further including if one or more of the conditions is detected repeatedly updating a display with an indicator of the condition that has caused the most inefficient fuel use 54 The method of claim 53 including filtering a display parameter to smooth fluctuations in the indicator UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO 6 092 021 Page lof 1 DATED July 18 2000 INVENTOR S Ehlbeck et al It is certified that error appears in the above identified patent and that said Letters Patent is hereby corrected as shown below Signed and Sealed this Sixteenth Day of October 2001 Miholos P Lodi Attest NICHOLAS P GODICI Attesting Officer Acting Director of the United States Patent and Trademark Office UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO 6 092 021 Page 1 of 1 DATED July 18 2000 INVENTOR S Ehlbeck et al It is certified that error appears in the above identified patent and that said Letters Patent is hereby corrected as shown below Column 10 Line 30 FSum Beta V A2Sum should read FSum Beta V 2Sum Column 13 Lines 33 54 the numbers appearing between this sub module are and vehicle velocity and engine RPM should not be bolded Column 15 Line 44 ESL p1 3 the should read ESL 3 the Column 17 Line 64 2BRSc should read 2 BRSc Column 20 Line 8 370 should
42. gn of the input device can vary The display device 72 provides a textual and graphical output to the driver display In one specific implementation the dis play device comprises a two line by 20 character vacuum fluorescent display The particular ICU used in this implementation is manu factured by Joseph Pollak of Boston Mass for Freightliner Corporation The instrumentation control unit is presently available as a replacement part from Freightliner Corpora tion The Data Link The data link 20 in this implementation is a serial communication path connecting the ECUs together This particular data link is designed according to SAE J1708 a standard for serial data communication between microcom puter systems in heavy duty vehicle applications While this specific embodiment is based on the J1708 standard it is not critical that the invention be implemented in this specific manner One possible alternative is to use a data link constructed according to SAE J1939 The communication link need not be a shared communication path It is also possible to connect vehicle parameter sensors i e for road 6 092 021 5 speed fuel rate RPM torque throttle position etc directly to the ICU via discrete wiring In the embodiment shown in FIG 1 the data link 40 is comprised of a twisted pair cable operating at 9600 baud Designed according to the SAE J1708 standard the data link forms a communication channel among the electronic con
43. gp then the geometric filter coefficient K is selected as follows If Lmpgp is less than 0 05 set K 1 otherwise set K 0 3 If Lmpg is greater than Lmpgp then set K 0 05 Once the value of the filter coefficient K is selected Lmpg is smoothed using the following Lmpg K Lmpg 1 K Lmpgp If the value of Lmpg is greater than 4 then scale Lmpg as follows Lmpg Lmpg 1 5 If the value of Lmpg is still greater than 4 9 then set Lmpg to 4 9 The display sub module bridges short discontinuities or dropouts in the selection of DCase This avoid messages flashing on and off in the driver message center When FLoss is greater than zero and Xcesa is greater than FLoss then the display sub module sets DCase PCase Otherwise it retains the value of DCase selected above Similarly if Lmpg is greater than 0 12 or DCase equals PCase then it retains the current value of DCase Otherwise it sets DCase equal to zero The Average Sub Module The average sub module updates the values of several variables in preparation for the next iteration FIG 16 illustrates an implementation of the average sub module First the values for the excess Xcesa and trip TFuela fuel are updated as shown in Steps 460 and 462 This implementation uses an asymmetrical geometric filter The effective time constants of this filter are specified by the inputs Tp and Tm Tau and Tau If the fuel use efficiency level is increasing FLoss gt 0 the geo
44. h of the fuel inefficient driving types Once this is determined the following information is updated and logged in memory of the ICU 1 driving type consuming the largest increment of fuel inefficiently 2 inefficient fuel consumed start of trip to current point 3 trip fuel start of trip to current point 4 short term inefficient fuel geometric averaged and 5 short term trip fuel geometric averaged The short term inefficient and trip fuel are used to calcu late the numeric value of FUEL EFFICIENCY which is displayed to the driver The Display Driver Module The Display Driver module 126 reads the analog inputs from the dash mounted driver operated keypad Analog input 130 to select preprogrammed messages available for display in the driver message center Current numeric values if needed are inserted into the message displayed One of the options available to the driver is the display 100 shown in FIG 4 Software Description The logic employed in each of these software modules is described in the following sections The Input Module The Input module 120 employs a parser to select parse and record into the array called the PID array all messages from the engine ECU The ICU receives vehicle perfor mance data from the data link in a serial data stream As noted above messages on the data link include an ID followed by one or more parameters and a checksum The parser executing in the ICU uses the ID
45. icle is consuming excess fuel during operation of the vehicle and for controlling the output device to indicate to the driver that excess fuel is being consumed including indicating during operation of the vehicle a quantity of fuel consumed due to the detected condition 36 The fuel efficiency indicator of claim 35 wherein the output device comprises a display device and the instru mentation control unit is operable to produce a display of a measure of excess fuel consumed due to the detected con dition 37 The fuel efficiency indicator of claim 35 wherein the output device comprises a display device and the instru mentation control unit is operable to produce a display of a message indicating the detected condition 38 The fuel efficiency indicator of claim 37 wherein the message indicates a driver action to reduce excess fuel consumption resulting from the detected condition 39 The fuel efficiency indicator of claim 37 wherein the condition comprises increased aerodynamic drag due to excessive vehicle speed 40 The fuel efficiency indicator of claim 37 wherein the condition comprises operating at high RPM 41 The fuel efficiency indicator of claim 37 wherein the condition comprises excessive idling 42 The fuel efficiency indicator of claim 37 wherein the condition comprises changes in kinetic energy due to brak ing or accelerating 43 The fuel efficiency indicator of claim 37 wherein the condition comprises rapid throt
46. icle speed BRSm gt MPH and the modified brake release speed is less than the confirmed brake application speed BRSm lt BASc 368 then it sets the confirmed brake release speed equal to the modified brake release speed 370 BRSc BRSm If the modified brake release speed is not greater than the current vehicle speed BRSm gt MPH but the modified brake release speed is less than the confirmed brake application speed BRSm lt BASc 372 then the updates section 306 sets the confirmed brake release speed equal to the current vehicle speed i e BRSc MPH Otherwise it sets the confirmed brake release speed to zero 376 If the confirmed brake release speed is greater than zero BRSc gt 0 and the brakes are not applied Brake 0 378 then it increments the elapsed timer 380 i e Et Et 0 2 Otherwise it sets the elapsed timer to zero 382 The last step in this section is to update the brake application indicator to the state of the brake 384 i e BAI Brake The Throttle Sub Module The throttle sub module calculates the increase in fuel consumed if any when the engine is accelerated rapidly During rapid engine acceleration the engine s specific fuel consumption exceeds the average or nominal value which results in increased fuel consumption The throttle module detects when rapid acceleration causes excess fuel consumption except in special cases where rapid throttle movement is justified such as during
47. in the vehicle s speed e g the most recent speed at which the brakes were applied BASp and released BRSp If the brakes are still applied BRSp is the current vehicle speed When the classification process is completed the braked speed change is either determined to be necessary no change in the confirmed state or unnecessary For unnec essary vehicle speed changes the kinetic energy in the confirmed state is increased by the amount of kinetic energy lost in the vehicle s speed change In addition the confirmed state speed BRSc is updated to BRSp and BASc is recal culated to reflect the increased braked change in kinetic energy and the updated BRSc FIG 12 is a flow diagram illustrating an implementation of the Braking Acceleration module This module is divided into four sections Confirm 300 Braking 302 BFuel 304 and Updates 306 Confirm This section of the module determines if pend ing braked changes in the vehicle s speed should be trans ferred to the confirmed state zeroed or retained in the pending state The first step 310 is to determine if pending braked changes in vehicle speed if any should be trans ferred to the confirmed state If the following conditions are true 1 pending brake applied speed an input is greater than zero BASp 0 2 the current vehicle speed is greater than the low speed limit MPH LSLim 3 the release application time is greater than the throttle brake time Rat g
48. ing This case is addressed by eliminating all conditions where the ratio of the vehicle speed divided by the engine speed is changing clutch disengaged or transmission in neutral before computing inefficient fuel consumption Also all conditions where the throttle position is less than the minimum throttle position or the vehicle speed is less than the low speed limit are eliminated before computing inefficient fuel use FIG 10 is a flow diagram illustrating an implementation of the RPM module As shown in FIG 10 the first step is to calculate the current engine speed limit ESL by sum ming the engine RPM limit plus one half the current engine horsepower as shown in Step 240 of FIG 10 i e ESL RLim HP 2 Next the value of the current vehicle speed MPH divided by the current engine speed RPM is calculated and compared to the previous vehicle speed engine speed ratio VEr value as shown in Step 242 If the following condi tions are satisfied 1 the current and previous vehicle speed engine speed ratios are within two percent 2 the engine speed is greater than the engine speed limit RPM gt ESL pl 3 the vehicle speed is greater than the low speed limit MPH gt LSLim and 4 the throttle position is greater than the minimum throttle position or cruise is engaged TC 1 244 then the RPM module sets the ratio status indicator RSI high 246 i e RSI 1 Otherwise it sets RSI 0 248 The last step is to calc
49. invention will become apparent with reference to the following detailed description and accompanying drawings BRIEF DESCRIPTION OF THE DRAWINGS FIG 1 is a block diagram illustrating the system archi tecture in a truck for one embodiment of the invention FIG 2 is a block diagram illustrating the engine electronic control unit ECU in more detail FIG 3 is a functional block diagram illustrating the architecture of the instrumentation control unit ICU FIG 4 is a diagram of a display format generated by the ICU in FIG 3 to display normal driving messages FIG 5 is another diagram of a display format generated by the ICU to indicate inefficient driving conditions and suggest an action to improve fuel efficiency FIG 6 is a flow diagram illustrating modules used to compute and display information about inefficient driving conditions in one embodiment of the invention FIGS 7A and 7B are a flow diagram illustrating an implementation of the Vehicle Parameter Estimation Mod ule of FIG 6 FIG 8 is a block diagram depicting a parameter sub module in the excess module shown in FIG 6 FIGS 9A and 9B are a flow diagram of speed sub module in the excess module for detecting inefficient fuel use due to speeding FIG 10 is a flow diagram of an RPM sub module in the excess module for detecting inefficient fuel use due to operating the vehicle at a high RPM FIG 11 is a flow diagram of an idling sub module in the excess module
50. le performance parameters 182 and computes a series of vehicle perfor mance parameters including horsepower 184 vehicle speed MPH 186 throttle position 188 specific fuel consumption 190 and status of the throttle whether or not cruise control is active 192 The variables with their definitions generated by this sub module are HP horsepower PID 93 PID 190 1050 190 k where k is a constant The specific value of k can vary depending on the vehicle Based on experimentation acceptable values for k include 1050 4 and 262 61 If the engine torque is negative set HP equal to zero MPH speed of the vehicle in miles per hour PID 84 2 PT percent throttle PID 91 2 55 RPM engine speed in revolutions per minute PID 190 4 SFC specific fuel consumption in gal hp hr PID 183 HP 64 If the engine horsepower is zero the ICU sets SFC equal to zero TC Throttle or Cruise 1 or 0 TC equals one if PT is greater than Tmin or bit 8 of PID 85 equals one Cruise Control Engaged FPI fuel per iteration in gallons Frate 18000 The parameters module also computes a quantity repre senting the ratio of vehicle velocity and engine RPM The Speeding Sub module The Speeding sub module calculates the fuel consumed if any due to increased aerodynamic drag when the vehicle speed exceeds the current vehicle speed limit The current speed limit is computed dynamically based on recent read ings of the vehicle s speed For
51. le speed limit by 5 mph 210 i e SLim SLim 5 sign Sa SLim Otherwise it maintains the current value of SLim Note that the sign function assumes the value 1 0 or 1 if the argument Sa SLim is greater than equal to or less than zero respectively The speeding module limits the value of SLim to a predetermined range e g between 55 and 75 as shown in Steps 212 and 214 If SLim is less than 55 or greater than 75 mph then it sets SLim equal to 55 or 75 respectively Next the speeding module calculates the incremental horsepower required to operate the vehicle AirP at speeds exceeding the current vehicle speed limit SLim as shown in Step 216 If the current vehicle speed is greater than the vehicle speed limit plus two miles per hour MPH gt SLim 2 to allow for normal speed variations then it calculates the incremental horsepower required due to increased aerody namic drag AFuel using the equation AirP Beta MPH 3 Sref 3 DTeff A75 91 Otherwise it sets AirP equal to zero If the throttle position is greater than the minimum throttle position or cruise is engaged TC 1 and the incremental aerodynamic horsepower is less than the engine horsepower 218 then the speed module calculates the inefficient fuel consumed due to the increased aerodynamic drag resulting from the higher operating speed AFuel as shown in Step 220 It uses the equation AFuel AirP SFCa 18000 If the throttle position is greater than th
52. m or this condition was the dominate cause of inefficient fuel use during the previous iteration DCase 4 and the ratio status indicator is high RSI 1 408 then the throttle module calculates the inefficient fuel consumed 410 In this implementation the throttle module uses the following equation to compute the excess fuel consumed due to rapid throttle movement MFuel DSFC HP 18000 RSI Otherwise it sets MFuel 0 The description above represents only one possible imple mentation of the throttle module In a second implementation the value of the throttle position is smoothed when it is updated using filtering Specifically in the second implementation the previous value of PTp is smoothed using a filtering expression of the form PTp k PID 92 1 k PTp or PT p k PT 1 k PTp The first expression with a k of 0 2 is used when the vehicle is operating in cruise control and the second expression with a k of 0 4 is used when cruise is not operating to smooth throttle movement caused by operating over bumps or rough roadways The Total Sub Module The total sub module accumulates from the start of the trip the actual fuel consumed the total fuel used ineffi ciently from all sources and the inefficient fuel for each of the sources FIG 14 is a flow diagram illustrating an implementation of the total module The actual trip fuel TFuel is accumu lated each iteration as follows TFuel 7Fuel FPI 420 The total excess
53. metric filter coefficient is C exp 0 2 Tm Otherwise it sets C exp 0 2 Tp Both Xcesa and TFuela are updated recursively as fol lows Xcesa C Xcesa FLoss and TFuela C TFuela FPI An alternative way to compute Xcesa is to compute a geometric average of the previous value of Xcesa and FLoss computed for the current iteration Similarly an alternative way to compute TFuela is to compute a geometric average of the previous value of TFuela and FPI for the current iteration For example Xcesa and TFuela can be updated as follows Xcesa 1 C Xcesa C FLoss and TFuela 1 C TFuela C FPI where C is a filter coefficient To minimize the possibility of unintentional throttle movement causing the THROTTLE SLOWER messages to be displayed the previous throttle position PTp is 10 15 20 25 30 35 40 45 50 55 60 65 24 calculated as a geometric average of the current and previ ous throttle positions 464 i e PTp 0 6PTp 0 4 PT The last step 466 in this sub module is to update the average specific fuel consumption SFCa using a long duration geometric average of the current and previous specific fuel consumption If the engine horsepower is greater than 10 percent HP gt 40 then SFCa is updated recursively using the following equation SFCa 0 995 SFCa 0 005SFC Otherwise it maintains the same value for the specific fuel consumption SFCa SFCa To accommodate engines of
54. ncy FIG 4 is an example of a display 100 used to display normal driving messages while FIG 5 is an example of a display 102 informing the driver that the vehicle is consuming excess fuel The display in FIG 5 replaces the one in FIG 4 when the system detects a condition where the vehicle is consuming excess fuel The fuel efficiency messages tell the driver when the vehicle is consuming excess fuel the cause of excessive fuel consumption and messages indicating actions that the driver can take to save fuel The fuel efficiency values are numeri cal representations of fuel efficiency There are a variety of different display formats that can be used to convey fuel efficiency messages and values to the driver and FIGS 4 and 5 represent only one example In the example shown in FIG 4 the display 100 shows normal driving messages 104 the current fuel economy in miles per gallon 106 and an odometer reading 108 A list of some examples of normal driving messages are in Table 2 provided below 6 092 021 7 TABLE 2 NORMAL DRIVING MESSAGES MPG Bargraph OUTSIDE TEMP xxx F COOLANT TEMP xxx F OIL PRESSURE xxx PSI ENGINE OIL TEMP xxx F FUEL TEMP xxx F BATTERY xx x VOLTS FUEL xx xx GAL HR TURBO BOOST xx PSI TUE JUN 24 11 21 AM SOMBNAMEWNE In an alternative implementation the display shows other fuel efficiency information during normal driving conditions i e when inefficient driving is not detected For exampl
55. ntation of the invention The instrumentation con trol unit comprises a CPU 60 memory 62 and a port interface 64 for connecting the unit to the data link 20 The memory 62 includes programmable ROM EEPROM 66 RAM 67 and permanent ROM 68 The routines for control ling the ICU are stored in ROM 68 while re configurable data is stored in the EEPROM 68 In one specific implementation the ICU includes a 68HC11 microprocessor from Motorola Corporation and its memory 62 comprises EEPROM ROM and RAM This specific ICU has 8 KB of external EEPROM 128K of ROM and 2K of RAM The internal memory of the CPU comprises 256 Bytes of RAM and 512 bytes of EEPROM This is only one specific implementation of the ICU A variety of con ventional processors and memory systems can be used to implement the functionality of the instrumentation control unit Preferably the processor used in the ICU should be a 16 bit processor The processor used in the current implemen tation was selected to have sufficient speed and memory to be able to evaluate five different fuel inefficient driving conditions every 200 ms This is not an absolute requirement however since the number of inefficient driv ing conditions that are monitored and the response time can vary The ICU also preferably includes an input device 70 and a display device 72 In one implementation the input device is a ten key keypad 70 but the specific design of the input device can vary The desi
56. of FIG 7A HP is greater than zero V is greater than 15 Brake 0 and n is less than 250 10 15 20 25 30 45 50 55 60 65 10 Otherwise it sets Case 0 Part 2 of the VPE Module Part 2 has two cases If Case from Part 1 equals zero then the variables n FSum V 2Sum Gr and VSum are set equal to zero 146 and the value of the variable Vo equal to the current vehicle velocity 148 If Case equals one then the VPE module increments the counter n by one i e n n 1 step 150 It then computes the average acceleration a 152 using the equation a V Vo n 32 2 and the current tractive force F 154 using the equation F 550 HP DTeft V Next the VPE module updates the sums used for esti mating the parameters as follows 156 FSum FSum F VSum VSum V and V2Sum V 2Sum4 V From this information the difference between the actual and the estimated vehicle velocity e is computed using the following equation 158 e V Vo 32 2 FSum Beta V A2Sum GCW n r If the vehicle is sustaining a high acceleration and torque n gt 5 amp a gt 0 011 amp Torque gt 500 decision step 160 then it selects the gain p for the vehicle s weight estimate update as follows 162 If the vehicle s velocity is less than 70 V lt 70 the VPE module sets p 500000 If the vehicle s velocity is not less than 70 it sets p 100000 Otherwise it sets the gain to zero p 0 164 The esti m
57. on 302 sets the pending brake application speed BASp to the current vehicle speed MPH i e BASp MPH If the brakes are applied and the previous brake applica tion speed is less than the current vehicle speed Brake 1 and BASp MPH but the current vehicle speed is less than the low speed limit or the throttle brake time is less than the release application time MPH LSLim or TBt lt RAt then it sets the pending brake application speed BASp to zero If neither of these conditions are true then it maintains the pending brake application speed BASp i e BASp BASp The next step is to update the pending brake release speed BRSp 322 If the brake application speed is greater than zero BASp gt 0 and the brakes are applied Brake 1 then the braking section sets the pending brake release speed BASp to the current vehicle speed MPH i e BRSp MPH If the brake application speed is greater than zero BASp gt 0 but the brakes are not applied Brake 0 then it sets the pending brake release speed BRSp to the previous pending vehicle speed BRSp i e BRSp BRSp If neither of these conditions are true then it sets the pending brake release speed BRSp to zero The last step 324 is to update the brake application indicator BAI If the brake application indicator is high BAI 1 or the vehicle is being braked Brake 1 then the braking section 302 sets the brake application indicator high 163 BAI
58. on of the fuel efficiency system and related methods in more detail The System Architecture FIG 1 is a block diagram illustrating the system archi tecture of electronic control units in a truck used to monitor vehicle performance data in an embodiment of the inven tion The system architecture includes a number of elec tronic control units ECU interconnected via a data link 20 In particular the system shown in FIG 1 includes an engine ECU 22 located at the engine and an instrumentation control unit 24 located at the dash of the truck As shown other optional ECUs 26 28 can be connected to the data link 20 Finally the system includes an optional data port 30 for coupling external data processing equipment to the ECUs on board the truck This data port enables an external computer for example to receive and transmit messages on the data link It also enables an external computer to download data ora file to an ECU and to receive data or a file from an ECU The Engine Control Unit FIG 2 is a block diagram illustrating the engine ECU used to collect vehicle performance data in the system shown in FIG 1 The engine ECU includes memory 40 a CPU 42 and a port interface 44 connected via a bus structure 46 The CPU 42 executes routines stored in the memory 40 to control and monitor engine performance The port inter face 44 serves as a link between the CPU 42 and a serial communication path called the data link 20 The engine ECU
59. or a J1708 data link Instead the data can be polled and buffered in memory of the control unit from discrete devices The software implementation can vary as well The sys tem above is organized into four modules but the same or similar logic can be implemented using a different software architecture and using a combination of software and hard ware logic The precise logic and the order in which steps are performed to detect excess fuel consumption and to compute excess fuel can vary The measures of excess fuel consumed and fuel efficiency can also be modified without departing from the scope of the invention For example excess fuel consumed can be con veyed as a volume of excess fuel or as an incremental value of fuel economy that reflects the decline in fuel economy due to an inefficient driving action Conversely the excess fuel consumed can be represented by a fuel economy value indicating the increase in fuel economy that could be obtained if a suggested driver action is taken Having described and illustrated the principles of my invention with reference to a specific embodiment and possible alternative embodiments it should be apparent that the invention can be modified in arrangement and detail without departing from its principles Accordingly we claim all modifications as may come within the scope and spirit of the following claims We claim 1 A method for assisting a driver of a vehicle to improve fuel economy while o
60. perating the vehicle on a roadway the method comprising collecting vehicle performance data during operation of the vehicle during operation of the vehicle monitoring for two or more conditions in which the vehicle is consuming excess fuel during operation of the vehicle detecting from the vehicle performance data whether at least one of the conditions exist in which the vehicle is consuming excess fuel and during operation of the vehicle indicating to the driver that excess fuel is being consumed due to the detected condition and a cause of the detected condition 2 The method of claim 1 wherein the condition comprises one or more of the following conditions increased aerody namic drag due to excessive vehicle speed operating at high RPM excessive idling changes in kinetic energy due to braking or accelerating or rapid throttle movement 3 The method of claim 1 further including displaying a message to the driver indicating a driving action that will improve fuel economy 4 The method of claim 1 wherein the condition comprises excessive speed 5 The method of claim 4 wherein the step of detecting the excessive speed condition includes comparing current vehicle speed to a reference speed 6 The method of claim 5 wherein the reference speed is dynamically updated based on recent speed readings of the vehicle 7 The method of claim 1 further including computing excess fuel consumed due to increased aero dyn
61. r a shift is or has occurred by determining the change in the ratio of vehicle velocity to engine speed The Excess module makes this determination in the parameters module rather than the RPM module In this version the parameters module updates VEr by filtering it and also uses filtering to update VEr when a shift has occurred The result of the shift determination is reflected in the variable RSI which is a binary value indicating the presence of a shift The value of RSI is then used in a preprocessing step in the RPM module and the throttle module to determine whether excess fuel should be evaluated The presence of a shift justifies high RPM and rapid throttle movement and thus serves as a prerequisite to computing excess fuel in the RPM and throttle modules The Idling Sub Module The idling sub module calculates the excess fuel con sumed if any due to engine idling Idling is defined as operation of the engine when the vehicle speed is less than 2 mph without the PTO engaged for a time period in excess of the idle time limit FIG 11 is a flow diagram illustrating an implementation of the idling module as shown in decision Step 270 The first step in this module is to determine if the engine is idling If the vehicle speed is less than 2 and the PTO is not engaged MPH 2 and PTO 0 270 then it sets the idling parameter to one Idling 1 272 Otherwise it sets the idling parameter to zero Idling 0 meaning that the vehicle is
62. rage module sets a floor of 30 for the value of eff so that the display driver uses at least a fuel efficiency value of 30 when computing display quantities The Display Driver Module The display driver module 126 FIG 6 acts as the interface between the ICU and the display hardware con nected to the ICU In this implementation the display hardware comprises a vacuum fluorescent display panel However the type of display device is not particularly critical to the invention In fact the system can indicate the presence of an inefficient driving action aurally instead of 6 092 021 25 visually For example the system could sound an alarm when inefficient fuel use is detected due to excessive speed high RPM excessive idling frequent braking and accelerating and rapid throttle movement The display driver 126 utilizes information generated in the input 120 VPE 122 and excess 124 modules and inputs from the driver keypad to select which of several pre programmed messages to display in the driver message center on the display panel Unless otherwise stated infor mation from the prior iteration is read from memory as an input at power on updated and stored in memory during each iteration and when the system is powered down This module executes when the fuel rate PID 183 information is updated every 200 ms The updated information is recorded in memory for use by the other modules The current implementation of the display
63. read 370 Le Column 27 Line 18 equal 100 should read equal to 100 Line 56 GAL Hr should read GAL Hr Signed and Sealed this Thirteenth Day of November 2001 Miholos P bac NICHOLAS P GODICI Attesting Officer Acting Director of the United States Patent and Trademark Office
64. s been idling from the start of the trip Time is initialized to zero when a new trip is inaugurated The initial startup value of ITime is zero the time in seconds which the engine has been idling for the current idling event ITime is initialized to zero when a new trip is inaugurated The initial startup value of ITime is zero the minimum speed necessary before inefficient fuel use is computed Below this speed inefficient fuel use is not computed LSLim is stored as a constant in memory the accumulated fuel in gallons used from the start of the trip due to rapid throttle movement MFuel is initialized to zero when a new trip is inaugurated The initial startup value of MFuel is zero the maximum value of the ratio of current Specific Fuel consumption SFC divided by average Specific Fuel Consumption SFCa which is allowed before excess or inefficient fuel is accumulated Over is stored as a constant in memory an array which contains the most recent information for PID s 0 through 253 from the J1587 1708 data bus for MID 128 Engine This array is updated by the INPUT module indicates if the power take off is operating PTO 1 It is updated each iteration based of the value of bit 8 of PID 89 the time between release of the throttle and application of the brakes or release of the brakes and application of the throttle RAt is initialized to zero when a new trip is inaugurated The initial startup value of RAt is zero the accumul
65. section of the Braking Acceleration module updates the release application RAt and elapsed time Et timers the confirmed brake release BRSc and application BASc speeds and the brake appli cation indicator BAI as follows If the brakes are applied and the brake application indi cator high Brake BAI and the throttle position TP is less than Tmin as shown in decision block 350 then the updates section 306 maintains the release application timer at its present value 352 i e RAt RAt If the brakes are not applied and the brake application indicator is low Brake BAI and the throttle position TP is less than Tmin 354 then it increases the release application timer 356 i e RAt RAt 0 2 Otherwise it sets the release application timer equal to zero 358 i e RAt 0 Next it calculates the modified brake release speed BRSm 360 using the following equation BRSm BRSc exp 0 0002 Ef If the current vehicle speed is less than the confirmed brake application speed MPH lt BASc and the modified brake release speed is less than the confirmed brake appli cation speed BRSm lt BASc 362 then the updates section maintains the current confirmed brake release speed 364 ie BASc BASc 10 15 20 25 30 35 40 45 50 55 60 65 20 Otherwise it sets the confirmed brake application speed to zero If the modified brake release speed is greater than the current veh
66. shifting To accommo date the need for rapid throttle movement when down shifting the throttle module does not evaluate inefficient fuel consumption whenever the ratio of the vehicle speed divided by the engine speed is changing clutch disengaged or transmission in neutral FIG 13 is a flow diagram illustrating an implementation of the throttle module The first step in this module is to determine 1 if the value of the current specific fuel con sumption is greater than the average specific fuel consump tion multiplied by the value specified by the input Over SFC gt SFCa Over and 2 if the vehicle speed is greater than the low speed limit MPH gt LSLim 400 If both of these conditions are true then the throttle module calculates the increase in specific fuel consumption DSFC 402 i e DSFC SFC SFCa Otherwise it sets DSFC 0 Next it evaluates the rate of change of the throttle If the throttle position is greater than the minimum throttle posi tion PT gt Tmin 404 then the throttle module calculates the rate of change of the throttle position TRate 406 as 6 092 021 21 the difference between the current throttle position TP and the previous averaged throttle position TPp i e TRate PT PTp Otherwise it sets TRate 0 The last step is to calculate the inefficient fuel used if any due to rapid throttle movement MFuel If the throttle rate is greater than the throttle rate limit TRate gt TLi
67. t Tbt 4 the throttle position is greater than Tmin or the brakes are applied TP gt Tmin or Brake 1 and 5 the brake application indicator equals zero BAI 0 then The confirm section transfers the kinetic energy in the pending state to the confirmed state as follows 312 BASc sqri BASc 2BRSc 2 BASp 2 and updates BRSc to BRSp i e BRSc BRSp 10 15 20 25 40 45 50 55 60 65 18 If the current vehicle speed MPH is less than the low speed limit LSLim or the release application time RAt is greater than the throttle brake time TBt 314 then it sets the pending brake applied and released speeds BASp and BRSp to zero 316 Holding the current information in the pending state occurs without any action if the conditions of these cases are not met 318 Braking This section of the braking accelerating mod ule updates the pending brake application and release speeds BASp and BRSp and the brake application indicator BAT all of its inputs The first step 320 is to update the pending brake application speed BASp If the following conditions are satisfied 1 the brakes are applied 2 the previous brake application speed is less than the current vehicle speed Brake 1 and BASp MPH 3 the low speed limit is less than the current vehicle speed LSLim lt MPH and 4 the release application time is less than the throttle brake time Rat TBt then the braking secti
68. the volume of fuel injected into a cylinder per revolution By determining the amount of time that the solenoid valves are closed the engine ECU computes the amount of fuel consumed by the engine The engine ECU calculates the fuel flow rate from the dwell of the injection pulse and the engine speed The engine ECU in this embodiment is also responsible for measuring and computing the vehicle s road speed The 10 15 20 25 30 35 40 45 50 55 60 65 4 speed control 50 senses the speed of rotation of the tail shaft of the transmission and converts it into road speed A magnetic sensor located on the tail shaft generates an analog signal comprised of a series of pulses representing the rotation rate of the tail shaft or drive shaft This analog signal is converted into a digital signal The engine ECU is programmed to read this digital signal and derive the instan taneous vehicle speed in miles per hour The engine ECU is responsible for monitoring a variety of other vehicle performance parameters including RPM and throttle position It derives engine torque from the fuel rate and turbo boost pressure These parameters are transferred to the instrumentation control unit over the data link The Instrumentation Control Unit FIG 3 is a functional block diagram illustrating the architecture of an instrumentation control unit ICU used to detect inefficient fuel use and control a driver display in one impleme
69. tion com prises a braked speed change that results in a loss of kinetic energy of the vehicle 17 The method of claim 16 further including determining elapsed time between applying brake and throttle to evaluate whether excess fuel is being con sumed 18 The method of claim 16 further including determining rate of increase of vehicle speed after a brake event to evaluate whether excess fuel is being con sumed 19 The method of claim 16 further including computing excess fuel consumed due to the braked speed change during operation of the vehicle 20 The method of claim 19 wherein the excess fuel consumed is computed as a function of change in kinetic energy due to braking 21 The method of claim 19 further including dynamically estimating gross vehicle weight and computing the excess fuel consumed based at least in part on the estimated gross vehicle weight 22 The method of claim 19 further including indicating the excess fuel consumed due to the braked speed change to the driver during operation of the vehicle 23 The method of claim 1 wherein the condition com prises excessive idling 24 The method of claim 23 further including determining whether idling time exceeds a reference time 25 The method of claim 23 further including computing excess fuel consumed due to excessive idling during operation of the vehicle 26 The method of claim 25 further including indicating the excess fuel consumed du
70. tle movement 44 A fuel efficiency indicator for a vehicle comprising a display device and an instrumentation control unit in communication with the display device the instrumentation control unit operable to receive vehicle performance parameters operable to detect from the vehicle performance data whether a condition exists in which the vehicle is consuming excess fuel and operable to control the 6 092 021 31 output device to indicate to the driver that excess fuel is being consumed in response to detecting the condition to indicate a message indicating a driver action to reduce excess fuel consumption due to the detected condition and to display a measure of excess fuel consumed due to the detected action 45 A method for assisting a driver of a vehicle to improve fuel economy while operating the vehicle on a roadway the method comprising collecting vehicle performance data during operation of the vehicle during operation of the vehicle monitoring for two or more conditions in which the vehicle is consuming excess fuel during operation of the vehicle detecting from the vehicle performance data whether at least one of the conditions exist in which the vehicle is consuming excess fuel measuring fuel consumption attributable to a detected condition in which the vehicle is consuming excess fuel and during operation of the vehicle indicating to the driver that excess fuel is being consumed due to the detecte
71. ulate the inefficient fuel used due to excessive engine speed RFuel as shown in Step 250 This implementation of RPM module uses the empirical equation RFuel RSI RPM Alim FPI 0 00015 The excess fuel is proportional to the amount by which the current RPM exceeds the engine speed limit For example the excess fuel is 1 596 per 100 RPM over a preprogrammed engine speed limit As noted above the engine speed limit is chosen based on empirical evidence and varies depending on the engine in the vehicle The description above represents one implementation of the RPM module In a second implementation the compu tations used to determine whether a shift has occurred are modified slightly The ICU determines whether a shift has occurred based on the ratio of vehicle velocity to engine 10 15 20 25 30 35 40 45 50 55 60 65 16 RPM VEr When a shift occurs the ratio of vehicle to engine velocity changes By detecting that the ratio has changed by more than a predetermined threshold e g two or three percent the ICU can detect when a shift has or is occurring It is sometimes beneficial to filter the value of VEr using an expression of the form VEr k MPH RPM 1 k VErp where k is a filtering coefficient and VErp is the previous value of the ratio It is also beneficial to use filtering to update the value of VEr slowly when a shift has occurred The second implementation the Excess module evaluates whethe
72. various horsepower ratings the 10 percent criteria described above should be initialized based on information from the engine ECU at power on In a second implementation the average module is also responsible for computing the instantaneous fuel economy IFE and a short term average fuel economy The IFE is calculated as IFE MPH FRate The short term average fuel economy is a weighted average of IFE and the previous value of short term average fuel economy STAFEnew C FE 1 C STAFEprevious where Cis a filter coefficient In this implementation C is selected dynamically based on a comparison between IFE and the previous value of STAFE Specifically if IFE is less than STAFE then C is set to 0 9 so that more weight is applied to IFE Otherwise C is set to the value of C1 an input to the ICU The average module can also compute the current fuel use efficiency level as follows eff 1 Xcesa TFuela 100 The average module uses filtering to smooth the value for fuel efficiency level In this implementation if the fuel efficiency level is greater than the value for the previous iteration of the Excess module then the value is smoothed as follows eff 0 1 eff 0 9 effp where effp is the previous value In this implementation the average module calculates the efficiency level so that there is a rapid change when its value is decreasing To accomplish this it uses no filtering if the fuel efficiency is declining The ave
73. vehicle performance data from the data link and uses selected parameters to detect inefficient driving conditions and compute excess fuel con sumed Table 1 below summarizes the selected parameters from the data link that the ICU uses to monitor fuel efficiency TABLE 1 PID 84 Speed PID 85 Throttle or Cruise Service Brakes PID 89 Power Take Off Bit 8 PID 91 Throttle Position PID 93 Engine Torque PID 121 Engine Retarder Status PID 183 Fuel Rate PID 190 RPM Fuel Efficiency Monitoring and Display System The system architecture described above is used to imple ment a fuel efficiency monitoring and display system The system monitors vehicle performance parameters and deter mines when the vehicle is consuming excess fuel It displays a combination of graphical and numerical quantities repre senting fuel efficiency and the excess fuel consumed due to a fuel inefficient driving action In addition it displays messages to prompt the driver when it detects that excess fuel is being consumed and suggests a driving action that will improve fuel economy FIGS 4 and 5 illustrate examples of a message display used to provide vehicle performance messages and values to the driver During normal driving conditions the message display provides normal driving messages When the system detects fuel inefficient driving it changes the display to indicate that the vehicle is consuming excess fuel and suggests an action that will improve fuel efficie

Fuel use efficiency system for a vehicle for assisting the driver to

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