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Contents
1. The automatic transmission 12 has a hydraulic con trol valve assembly 20 The control valve assembly 20 has a plurality of solenoids including shift solenoids and a line pressure solenoid The solenoid 16 of the exhaust brake system 14 and the plurality of solenoids of the control valve assembly 20 are operatively connected to a microcomputer based control unit 18 Supplied to the control unit 18 are signals generated by the exhaust brake switch 22 a select position detect ing switch i e an inhibitor switch 24 a vehicle speed sensor 26 and an accelerator position sensor 28 in the form of a throttle opening degree sensor if the engine has a throttle which opens in degrees If the engine 10 is a diesel engine which is not provided with a throttle valve the accelerator position sensor 28 directly mea sures the position or depressing degree of the accelera tor pedal The selector lever has a N neutral range a D drive range and a 2 range When the manual selec tor lever is placed at the 2 range or a power shift switch is set at POWER position with the manual selector lever at D range the automatic transmission 12 is shift able to an engine brake running state where a direct motion connection is established between the input and output shafts 12a and 125 The inhibitor switch 24 de tects which one of the plurality of positions the manual selector lever is placed at The vehicle speed sensor 26 detects a revolution speed of the2. beginning with the command for the 3 2 downshift The setting of the predetermined period of time is such that the exhaust brake is inoperable while the 3 2 downshift is in progress in the automatic trans mission 12 Upon elapse of the predetermined period of time the control unit 18 allows the exhaust brake to become operable again so that the supply of electric current to the solenoid resumes if the exhaust brake switch 22 is left turned on Thus strong engine brake becomes effective again upon completion of the 3 2 downshift The control unit 18 stores a program as illustrated in FIG 2 and executes the program to perform the opera tion described above 20 45 55 60 65 4 Referring to FIG 2 in a step 100 it is determined whether or not there is a command for engine brake running state by checking the output signal of the inhib itor switch 24 or checking the state of the power shift switch The inquiry in this step 100 results in affirmative when the manual selector lever is set to 2 range or the power shift switch is set to POWER position with the manual selector lever set to D range Otherwise the inquiry results in negative If the inquiry of this step 100 results in negative the execution of this program ends If it results in affirmative the program proceeds to a step 101 where it is determined whether or not there is a command o4 requirement for a 3 2 downshift If the inquiry of this step 101 results in n
3. motor vehicle having an engine and an automatic transmission the automatic transmission having an input shaft and an output shaft and being shiftable to an engine brake run ning state wherein a direct motion connection is estab lished between the input and output shafts the motor vehicle also having an exhaust brake system the method comprising the steps of generating a command for the engine brake running state and rendering the exhaust brake system inoperable tem porarily for a predetermined period of time when a predetermined shift is in progress after said com mand has been generated 6 A method as claimed in claim 5 wherein said pre determined period of time is variable with a vehicle speed of the motor vehicle 7 A method of exhaust brake control in a motor vehicle having an engine and an automatic transmission the automatic transmission having an input shaft and an output shaft and being shiftable to an engine brake run ning state wherein a direct motion connection is estab lished between the input and output shafts the motor vehicle also having an exhaust brake system the method comprising the steps of generating a command for the engine brake running state determining whether or not there is a command for a predetermined shift in the automatic transmission and rendering the exhaust brake system inoperable for a predetermined period of time when said predeter mined shift is in progress after said co
4. selec tor lever having a D range and a 2 range When the 2 range is selected by the manual selector lever the auto matic transmission is conditioned in engine brake run ning state where a direct motion connection is estab lished between the transmission input and output shafts If under this condition an exhaust brake switch is turned on an exhaust brake system becomes in opera tion to cause activation of exhaust brake With the auto matic transmission in the engine brake running state and the exhaust brake activated if the vehicle speed drops down to a vehicle speed value at which the automatic transmission effects a downshift a great shift shock cannot be avoided The present invention aims at allevi ating this problem SUMMARY OF THE INVENTION The present invention ensures a shock less shift after the automatic transmission has been conditioned for engine brake running state by rendering an exhaust brake system inoperable temporarily for a predeter mined period of time when the shift is in progress in the automatic transmission According to the present invention a motor vehicle having an automatic transmission and an exhaust brake system is provided with means for generating a command for engine brake running state and means for rendering the exhaust brake system inoper able temporarily for a predetermined period of time when a predetermined shift is in progress in the auto matic transmission after said command has
5. VIA US005088348A United States Patent 15 1 Patent Number 5 088 348 Hiramuki 45 Date of Patent Feb 18 1992 54 EXHAUST BRAKE CONTROL OF MOTOR 4 966 110 10 1990 Seki et al 123 321 X VEHICLE WITH AUTOMATIC 4 996 893 3 1991 Nakamura et al 74 866 TRANSMISSION FOREIGN PATENT DOCUMENTS 75 Inventor Michiaki Hiramuki Shizuoka Japan 62 204042 9 1987 Japan 73 Assignee Jatco Corporation Japan OTHER PUBLICATIONS 21 Appl No 669 889 Service Manual Nissan Full Range Electronically 22 Filed Mar 14 1991 Controlled Automatic Transmission E AT RE4RO1A R en Type A2671C07 no date 30 Foreign Application Priority Data Automotive Engineer s Hand Book pp 6 46 and Sep 14 1988 JP Japan Le 63 228807 6 47 no date 51 Int CUS eerte tetas F02D 9 06 Primary Examiner Dirk Wright 52 US Cl 58 Field of Search 74 859 123 322 74 859 860 878 123 321 322 Attorney Agent or Firm Ronald P Kananen 57 ABSTRACT An exhaust brake control ensures a shock less shift after 56 References Cited the automatic transmission has been conditioned for U S PATENT DOCUMENTS engine brake running state by rendering an exhaust 2 393 579 1 1946 Weiss et al 13 322 brake system inoperable temporarily for a predeter 3 710 908 1 1973 Muir sss 74 878 X mined period of time when the shift is in progress in the 4 188 933 2 1980 Iizuka u s 123 322
6. been gener ated According to one embodiment the predetermined period of time is variable with the vehicle speed According to another aspect of the present invention there is provided a method of exhaust brake control in a motor vehicle having an engine and an automatic transmission the automatic transmission having an input shaft and an output shaft and being shiftable to an engine brake running state wherein a direct motion connection is established between the input and output shafts the motor vehicle also having an exhaust brake system the method comprising the steps of generating a command for the engine brake running state and rendering the exhaust brake system inoperable tem porarily for a predetermined period of time when a predetermined shift is in progress after said command has been generated BRIEF DESCRIPTION OF THE DRAWINGS FIG 1 is a block diagram of a motor vehicle with an exhaust brake system control according to the present invention FIG 2 is a flow diagram of a program stored in a control unit shown in FIG 1 10 15 20 25 30 50 55 60 65 2 FIG 3 is a flow diagram of a timer program stored in the control unit and FIG 4 is a flow diagram of a modification of the program shown in FIG 2 DETAILED DESCRIPTION OF THE INVENTION Referring to FIG 1 a motor vehicle is shown in a block diagram which includes an engine 10 and an auto matic transmission 12 The automatic trans
7. egative the execution of this program ends If this inquiry results in affirma tive the program proceeds to a step 102 where a timer T is reset to O zero and then to a step 104 where the exhaust brake is rendered inoperable even if the exhaust brake switch 22 is turned on by suspending electric current passing through the solenoid 16 After suspend ing the supply of electric current supplied to the sole noid 16 the program proceeds to a step 106 where it is determined whether or not the timer T is greater than a predetermined period of time T The time T is incre mented in a step 110 upon executing a program of FIG 3 upon elapse of a predetermined period of time Refer ring back to FIG 2 the step 106 is repeated as long as the timer T is not greater than T Upon elapse of the predetermined period of time T after the command for 3 2 downshift has occurred the timer T becomes greater than T and the inquiry of the step 106 results in affirmative Thus the program proceeds to a step 108 where the exhaust brake is rendered operable to allow supply of electric current to the solenoid 16 if the ex haust brake switch 22 is left turned on The setting of the predetermined period of time Tj is such that the 3 2 downshift is completed prior to elapse of this period of time It will now be appreciated that since the activation of exhaust brake is suspended while a predetermined shift is in progress in the automatic transmission after a c
8. mission 12 is of the well known RE4ROIA type and described in a service manual NISSAN FULL RANGE ELEC TRONICALLY CONTROLLED AUTOMATIC TRANSMISSION E AT RE4ROIA TYPE A261C07 which was issued by Nissan Motor Co Ltd in March 1987 This publication is hereby incorporated by reference in its entirety The automatic transmission 12 has an input shaft 12a i e a turbine shaft coupled with a turbine runner of a torque converter 11 whose pump impeller is coupled with the engine 10 An output shaft 12b of the automatic transmission is drivingly connected to driving wheels only one of which being shown at 13 For increased engine braking the engine 10 is equipped with an exhaust brake system 14 A typical example of such an exhaust brake system is described on pages 6 46 and 6 47 of AUTOMOTIVE ENGIN NER S HAND BOOK published by Society of Auto motive Enginners of Japan Briefly the exhaust brake system 14 is constituted by a valve arranged for closing the engine exhaust system and a cooperating valve ar ranged in the engine intake system means including a solenoid 16 for closing the valve in the exhaust system in response to energization of the solenoid 16 and a manually operable exhaust brake switch 22 disposed near a driver s seat According to the known control strategy releasing an accelerator pedal after the exhaust brake switch 22 has been turned on causes energization of the solenoid 16 causing activation of exhaust brake
9. mmand for the engine brake running state has been generated
10. ne brake is accomplished In this automatic transmission 12 the engine brake running state is established when an overrunning clutch is engaged This overrunning clutch is engaged when the vehicle speed drops to a predetermined value with the accelerator pedal released after the power shift switch has been set to a POWER position for select ing a power shift pattern with the manual selector lever placed at D range of after the manual selector lever has been moved from D range to 2 range For further infor mation reference should be made to pages I 30 to I 32 of the before mentioned service manual NISSAN FULL RANGE ELECTRONICALLY CON TROLLED AUTOMATIC TRANSMISSION E AT RE4RO1A TYPE A261C07 For operation and con trol of the overrunning clutch of this automatic trans mission reference should be made to U S Pat No 4 680 992 issued to Hayasaki et al on Jul 21 1987 which is hereby incorporated by reference in its en tirety i As the vehicle speed drops down to a vehicle speed value at which a predetermined shift for example a 3 2 downshift is to take place The control unit 18 deter mines that a command for the 3 2 downshift is available upon making a judgement that the target speed ratio is the second speed ratio and the actual speed ratio re mains the third speed ratio Then the control unit 18 renders exhaust brake inoperable by suspending electric current supplied to the solenoid 16 for a predetermined period of time
11. om mand for engine brake running state has become avail able the automatic transmission effects the predeter mined shift without substantial shock Upon completion of the shift strong engine brake is provided Since a period of time required for a shift is depen dent on vehicle speed it is desired to vary the above mentioned predetermined period of time in proportion to varying vehicle speed This can be accomplished by slightly modifying the program of FIG 2 FIG 4 shows such a modification Referring to FIG 4 this program is different from the program of FIG 2 in the provision of two steps 200 and 202 between the steps 102 and 106 In the step 200 a reading operation is performed on the output signal of the vehicle speed sensor 26 to store the result as a vehi cle speed V In the subsequent step 202 the predeter mined period of time T is set as a function of the vehi cle speed V stored in the previous step 200 What is claimed is 1 In a motor vehicle having an engine and an auto matic transmission the automatic transmission having an input shaft and an output shaft and being shiftable to an engine brake running state wherein a direct motion connection is established between the input and output shafts the motor vehicle also having an exhaust brake system 5 088 348 5 means for generating a command for the engine brake running state and means for rendering the exhaust brake system inoper able temporarily f
12. or a predetermined period of time when a predetermined shift is in progress in the automatic transmission after said command has been generated 2 A motor vehicle as claimed in claim 1 further comprising means for detecting a vehicle speed of the motor vehicle and generating a vehicle speed indicative signal indicative of said vehicle speed detected 3 A motor vehicle as claimed in claim 2 wherein said predetermined period of time is variable with said vehi cle speed indicative signal 4 In a motor vehicle having an engine and an auto matic transmission the automatic transmission having an input shaft and an output shaft and being shiftable to an engine brake running state wherein a direct motion connection is established between the input and output shafts the motor vehicle also having an exhaust brake system means for generating a command for the engine brake running state means for detecting a vehicle speed of the motor vehicle and generating a vehicle speed indicative signal indicative of said vehicle speed detected and means for setting a predetermined period of time variable with said vehicle speed indicative signal and rendering the exhaust brake system inoperable temporarily for said predetermined period of time when a predetermined shift is in progress in the automatic transmission after said command has been generated 15 25 30 35 45 50 55 65 6 5 A method of exhaust brake control in a
13. transmission output shaft 125 and thus a vehicle speed of the motor vehicle and generates a vehicle speed indicative signal indica 5 088 348 3 tive of the vehicle speed The accelerator position sen sor 28 detects an opening degree of the engine throttle or a depression degree of the accelerator pedal and generates an accelerator depression degree indicative signal indicative of the throttle opening degree or the accelerator depression degree detected Operation of this embodiment is as follows With the manual selector lever placed at D range the control unit 18 reads output signals of the vehicle speed sensor 26 nd accelerator position sensor 28 and deter mines a desired or target speed ratio after retrieving a predetermined shift point mapping based on the output signals In accordance with the output signals of the control unit 18 supplied to the shift solenoids of the control valve assembly 20 the automatic transmission 12 automatically shifts among the first second third and fourth speed ratio when the manual selector lever is placed at D range Let us now assume that the vehicle travels with the third speed ratio established in the automatic transmission 12 If the driver turns on the exhaust brake switch 22 and releases the accelerator pedal the solenoid 16 of the exhaust brake system 14 is energized Subsequently under this condition if the automatic transmission 12 shifts to the engine brake running state strong engi
14. x Automatic transmission 4 680 992 7 1987 Hayasaki et al 74 869 4 742 806 5 1988 Tart Jr et al 123 322 7 Claims 3 Drawing Sheets TORQUE CONVERTER 0 22 EXHAUST BRAKE SWITCH 24 INHIBITOR SWITCH 26 VEHICLE SPEED SENSOR 28 ACCELERATOR POSITION SENSOR Il jos 2 AUTOMATIC TRANSMISSION U S Patent Feb 18 1992 Sheet 1 of 3 5 088 348 FIG 1 TORQUE CONVERTER O 2 AUTOMATIC ll 129 TRANSMISSION y b 13 H se x 22 EXHAUST BRAKE SWITCH 24 INHIBITOR SWITCH CONTROL 26 UNIT VEHICLE SPEED SENSOR 28 ACCELERATOR POSITION SENSOR U S Patent Feb 18 1992 Sheet 2 of 3 5 088 348 FIG 2 START OO IS COMMAND FOR ENGINE BRAKE AVAILABLE NO IS COMMAND FOR 3 2 DOWNSHIFT AVILABLE YES 02 RESET T 0 104 RENDER EXHAUST BRAKE INOPERABLE RENDER Tr ee RETURN U S Patent Feb 18 1992 Sheet 3 of 3 5 088 348 FIG 4 START OO IS CONNABD FOR ENGINE BRAKE AVAILABLE IS COMMAND FOR 3 2 DOWNSHIFT AVILABLE 5 088 348 1 EXHAUST BRAKE CONTROL OF MOTOR VEHICLE WITH AUTOMATIC TRANSMISSION BACKGROUND OF THE INVENTION The present invention relates to a motor vehicle in cluding an automatic transmission and an engine with an exhaust brake system and more particularly to a control of such an exhaust brake system A known automatic transmission has a manual
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