Current controlled fluid bleed
Contents
1. Fisher Controls Kent ME England Model 546 and 546S Electropneumatic Controls Bulletin 62 1 546 Feb 1981 Primary Examiner Noah P Kamen Attorney Agent or Firm Alvin S Blum 57 ABSTRACT A fluid bleed device for controlling the amount of natu ral gas supplied to the carburetor of a turbocharged carbureted natural gas engine provides a regulated out put fluid pressure to the setpoint of the natural gas sup ply regulator feeding the carburetor This regulated output fluid pressure is related to the magnitude of two input variables the turbocharger output pressure and an electric signal from an exhaust gas sensor reflecting the engine exhaust gas composition Turbocharger air input to the bleed device passes through two restrictive ori fices and a nozzle in series The nozzle is variably oc cluded by a movable member controlled by an electro magnet powered by the electric signal The regulated output fluid pressure is taken from the junction between the two restrictive orifices to supply a pressure to the gas supply regulator that is related to both turbocharger outlet pressure and the exhaust gas composition for enhanced engine efficiency 5 Claims 3 Drawing Sheets U S Patent Apr 21 1992 Sheet 1 of 3 5 105 790 U S Patent Apr 21 1992 Sheet 2 of 3 5 105 790 FIG 2 24 Bar eae 50 U S Patent Apr 21 1992 Sheet 3 of 3 5 105 790 FIG 3 49 44 50 46 60 63 62 FIG 4 a2. soft iron pole piece 40 nozzle 43 nozzle orifice 46 input orifice 44 channel 48 input pressure port 49 output pressure port 50 zeroing magnets 52 zero adjustment 54 damp ing vane 56 damping oil 58 exhaust port 59 and unit enclosure 60 When an electric current passes through force coil electromagnet 36 the magnetic field gener ated therein opposes the field of magnet 38 forcing the balance shaft 32 upward With the device depicted as in FIG 2 an input cur rent into force coil 36 causes balance shaft 32 to ap proach the open end of nozzle 43 and at this point with the proper setting of zero adjustment 54 nozzle 43 is not materially obstructed with respect to air flow resulting in maximum air flow through orifices 44 and 46 The pressure drop at outlet port 50 is then near its maximum with these settings As balance shaft 32 moves closer to nozzle 43 air flow is reduced reducing the pressure drop at outlet port 50 until nozzle 43 is completely sealed off When nozzle 43 is completely sealed off there is no pressure drop at outlet port 50 and the pres _ sure is equal to input pressure at port 49 The pressure in nozzle 43 is self adjusting up to the point of being sealed off such that the fluid force on balance shaft 32 bal ances the force produced by force coil 36 and other forces on balance shaft 32 This insures that device 24 of the invention has stable and linear characteristics Zero ing magnets 2 oppose each othe
3. ON OF THE PREFERRED EMBODIMENTS FIG 1 shows an air fuel ratio control system 10 for use with turbocharged carbureted natural gas engine In this system gas pressure regulator 12 with gas supply 15 25 40 45 55 60 65 2 as input supplies regulated gas typically 5 psig 14 to carburetor 16 The engine speed is controlled by gover nor 18 in conjuction with butterfly valve 20 at outlet of carburetor 16 Engine intake manifold 17 conducts air and gas mixture to the engine Gas pressure 14 is set by the setpoint spring 22 in regulator 12 and by the pres sure biasing or loading pressure from the current con trolled bleed device 24 of the invention The current controlled bleed unit 24 is supplied with compressed air from the turbocharger 19 after the intercooler 23 and it also receives d c current via cable 29 from the propor tional plus integral air fuel ratio controller 28 Current controlled bleed unit 24 has a small exhaust flow from outlet 25 This is air exhaust in the system 10 since the supply air applied to the bleed unit 24 is air from turbo charger 19 The contro loop is closed by supplying controller 28 with an electrical signal from oxygen sensor 30 located in the exhaust manifold of the engine FIG 2 is a cross section view of the current con trolled bleed unit 24 of the invention The device incor porates balance shaft 32 flexures 34 spring bias flexures 34 force coil 36 coil terminals 37 magnet 38
4. United States Patent 1 9 Nye Jr CAN AA A US005105790A 11 Patent Number 45 Date of Patent 5 105 790 Apr 21 1992 54 CURRENT CONTROLLED FLUID BLEED 76 Inventor Dudley D Nye Jr 4020 Galt Ocean Dr 606 Fort Lauderdale Fla 33308 21 Appl No 633 394 22 Filed Dec 21 1990 SDE CA o K F02B 43 00 52 U S C oe 123 527 251 129 22 58 Field of Search 123 527 528 137 82 251 129 22 56 References Cited U S PATENT DOCUMENTS 3 621 862 11 1971 Wojtecki 137 82 137 82 3 799 498 3 1974 Wickham et al 4 084 539 4 1978 Schmidt 0 0 cesses 118 8 4 294 214 10 1981 Treible 137 495 4 325 399 4 1982 Frick eecsecssescetsseseesenenenees 137 85 4 481 967 11 1984 Frick 137 85 137 85 4 653 523 3 1987 Brown 3 4 665 938 5 1987 Brown et al w 137 85 4 729 398 3 1988 Benson et al 137 82 4 811 720 3 1989 Katumata etal we 123 527 4 836 011 6 1989 Dombrowski et al 73 4 R 4 874 005 10 1990 Potter usssessessssersererrsrssssresss 137 85 4 901 756 2 1990 Rovner 137 487 5 4 905 720 3 1990 Benson ou eecseeesesesesesceeeees 137 82 OTHER PUBLICATIONS Moore Products Co Spring House Pa Model 771 I P Transducers Installation Service Manual Feb 1986 Hammel Dahl Electropneumatic Transducer Model T 28 Grinnell Valve Co Warwick R L Dec 1977 Instructions HDC 14048
5. d controls the pressure of fuel gas coming from a supply 15 by opening and closing valve 92 that is con nected to diaphragm 91 until the forces on both sides of diaphragm 91 are equal Gas pressure in chamber 94 is the only force on a first side of the diaphragm and will reflect the regulator outlet pressure in conduit 14 sup plying fuel to the carburetor 16 The second side of diaphragm 91 has two forces acting on it An adjustable spring bias 22 which is well known in the art and a second force the gas pressure in chamber 26 as sup plied by conduit 93 This controlling gas pressure is regulated by a sensor 30 in the exhaust stream of the engine not shown to modulate the carburetor fuel supply for cleaner fuel burning to reduce stress on the environment and any catalytic converter FIG 4 shows the input to output pressure drop of the current controlled bleed device of the invention as a function of input pressure derived from the turbo charger and the input current derived from the air fuel The turbocharger pressure is initially at a very low value when the engine is first started It then gradually builds up with engine temperature and load application The turbocharger air output pressure reaches a maxi mum value of typically 5 psig as controlled by a regu lator not shown on the engine exhaust side of the turbocharger Since the lines in the graph shown are almost parallel there is very little proportional gain change when co
6. k wil 3 PSIG ie INPUT TO OUT PRESSURE DROP PSI l 2 3 4 5 INPUT CURRENT MA 5 105 790 1 CURRENT CONTROLLED FLUID BLEED BACKGROUND OF INVENTION This invention relates to a stable and calibratable fluid bleed unit which can be used as a controlling element in air fuel control systems for turbocharged carbureted natural gas reciprocating engines Presently com pressed air from the turbocharger is used as a loading pressure on the spring or setpoint side of the gas pres sure regulator Gas pressure to the carburetor is then automatically increased when more air produced by the turbocharger and this combined with the design of the carburetor keeps the air fuel ratio about constant This is not quite good enough however for obtaining maxi mum life from a catalytic converter when used and for minimizing pollution The current controlled fluid bleed device of this in vention is used to bleed and reduce the air pressure applied to the setpoint side of the fuel gas regulator set to run the engine slightly rich so as to trim the air fuel ratio in response to the current output of a proportional plus integral controller This results in more perfect control of the air fuel ratio SUMMARY OF INVENTION The current controlled bleed unit of the invention resembles in some respects certain current to air pres sure transducers available for industrial instrumentation systems except that is does not have an output pressure de
7. le member and said body member and 10 20 25 45 50 55 60 65 4 a Stationary second magnetic means connected to said body member and arranged to interact magneti cally with said first magnetic means to thereby apply a moving force to said movable member for variably occluding said outlet end of said nozzle at least one of said magnetic means being an electro magnet in which a magnetic field is generated by an electric current applied thereto by said variable electric current whereby said electric current controls the magnetic force regulating the force on said movable member for variably occluding said nozzle and the force occluding said nozzle regulates the flow of said pressurized supply fluid through said restrictions and past the partially occluded nozzle and the fluid pressure at said outlet port wil be substantially equal to the pressure at the outlet of said second restriction and that pressure will be controlled by the magnitude of said electric current in combina tion with the pressure of said pressurized supply fluid 2 A current controlled bleed device according to claim 1 in which said bias force is provided by a spring connected between said movable member and said body member 3 A current controlled bleed device according to claim 1 in which said bias force is obtained by magnetic force provided by permanent magnets with one magnet connected to said body member and another magnet connected to
8. nsidering the closed loop system of FIG 1 The invention has been described with reference to the preferred embodiments Obviously modifications and alterations will occur to others upon reading and understanding the preceding detailed descriptions It is intended that this invention be construed as including all such alterations and modifications insofar as they come within the scope of the appended claims or the equivalents thereof Having thus described the preferred embodiments the invention is now claimed to be 1 An electric current controlled fluid bleed device comprising a body member having a fluid inlet port an outlet port and an exhaust port said inlet port arranged for supplying pressured fluid thereto a movable member with a first magnetic means for providing a magnetic field rigidly attached thereto a channel connecting said inlet port to said outlet port a branch line connected intermediate said channel to be variably occluded by said movable member two restrictions a first restriction located in said branch line and a second restriction located in said channel upstream of said branch line a nozzle having an inlet end and an outlet end with the outlet end arranged to be variably occluded by said movable member and with the inlet to said nozzle communicating with said branch line conduit means for conducting fluid from said nozzle to said exhaust port bias means for applying a bias force between said movab
9. pendent on d c input current only The output pres sure of the bleed unit of the invention is a function of a pressure input as well as the d c input current A closed loop air fuel ratio contro system is reduced in com plexity by using the bleed unit of the invention This results in lower costs and increased reliability It is therefore one object of the invention to provide a fluid bleed unit controlled by a d c current usually 1 5 mA or 4 20 mA Another object is to provide a fluid bleed unit which can be used on natural gas as well as air Another object of the invention is to set forth a com plete closed loop control system for air fuel ratio con trol incorporating the current controlled bleed unit of the invention These and further objects and advantages of the in vention will become more apparent upon reference to the following specifications drawings and claims wherein BRIEF DESCRIPTION OF THE DRAWINGS FIG 1 is a simplified drawing of a fuel to air ratio control system incorporating the current controlled bleed unit of the invention FIG 2 is a cross sectional drawing showing the con struction of the current controlled bleed unit of the invention FIG 3 is a combination block diagram and equivalent schematic for the bleed unit of the invention FIG 4 is a graph representing the input to output pressure drop of a typical bleed unit as a function of input d c current and input pressure DETAILED DESCRIPTI
10. r to support balance shaft 32 and to provide for a calibration adjustment via screw 54 Damping vane 56 in damping oil 58 prevents the closed loop mechanical spring and mass system from oscillating Alternatively the buoyancy of damp ing vane 56 and the spring bias of flexures 34 may be arranged to provide sufficient upward bias to balance shaft 32 to eliminate zeroing magnets 52 FIG 3 is block schematic drawing of the current controlled bleed device of the invention Here signal 49 representing pressure from the turbocharger in FIG 1 is directed to the input of orifice 44 and the output of orifice 44 is connected to a terminal representing the outlet pressure port 50 of device 24 of FIG 1 Flow controlled by the pressure at 63 determines the drop in outlet pressure 50 Current input 60 controls pressure 63 via block 62 The transfer function for the ratio of a pressure change at 50 to a current change at 60 is essen tially constant for a given selection of orifices 44 and 46 5 105 790 3 This is important when considering the proportional gain of the closed loop system of FIG 1 It has been suggested by others that the variable bleed device might incorporate a motor positioned needle valve for orifice 46 But this would result in variation of the proportional loop gain of the closed loop system of FIG 1 and result in sluggish response at the low flow end of orifice 46 settings A modified gas pressure regulator 90 reduces an
11. said fluid pressure outlet a branch line connected intermedi ate said channel two restrictions a first restriction located in said channel upstream of said branch line and a second restriction located in said branch line an aperture means for conduction of fluid there through located in said branch line downstream of said second restriction said fluid exhaust port 5 105 790 5 being connected downstream of said apperture means in said branch line and c a movable member having attached thereto an aperture occluding means for variably occluding said aperture means said movable member ar ranged for movement within said body under a moving force generated by a biasing means in com bination with a variable electrical current supplied by connection to said electrical current input wherein said aperture occluding means variably 10 15 20 25 30 35 45 50 55 65 6 occludes said aperture means with a force that varies in relation to said electrical current whereby the outlet fluid pressure reflects the inlet fluid pressure minus the pressure drop across the first restric tion and the pressure drop across the first restriction is related to the fluid flow therethrough which is related to the occluding force produced by said variable electri cal current
12. said movable member 4 The bleed device according to claim 1 further comprising a fuel gas pressure regulator having an inlet for a supply of fuel gas and an outlet for supplying gas fuel to an internal combustion engine at a con trolled gas pressure regulated by the composition of exhaust gas emitted by said engine in which said controlled gas pressure is controlled by a gas pres sure regulator provided with a diaphragm having two broad faces with said gas fuel on a first broad face and a controlling force applied to a second broad face said controlling force provided by a setpoint spring and by a loading or biasing fluid pressure in combination a conduit connection means for fluid connection be tween said pressure regulator and said outlet port of said bleed device for providing said biasing fluid pressure and an exhaust gas sensing means for sensing the composi ton of the exhaust gas from the engine said sensing means including means for generating said variable electric current for applying to said electromagnet of said bleed device 5 A transducer for providing an output fluid pressure whose magnitude is related to the magnitude of two different input variables an inlet fluid pressure and an inlet electrical current the transducer comprising a a transducer body having a pressurized fluid inlet a fluid pressure outlet a fluid exhaust port and an electrical current input b a channel connecting said fluid inlet to
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