FUEL INJECTION SYSTEM

Abstract: A bistable fluidic switch (10) is switched from its stable state by a pin (19) inserted in the power nozzle (12) of the bistable fluidic switch (10), the pin (19) being controlled by an electromagnetic actuator (21) which is controlled from an electronic computer (22). The fluidic switch element (10) has a cross-over type interaction region (13) and a common outlet (16) leading to a pair of output passageways (17, 18), one of which (18) returns fuel to the supply tank, and the other of which (17) leads to the air intake manifold of the engine. Air is introduced into the output passageway (17) leading to the engine so as to air atomize the fuel before injection of same into the air intake manifold.

Description: FUEL INJECTION SYSTEM REFERENCE TO RELATED APPLZCATZONS This application is related to the application of Ronald D. Stou±fer, U.S. Serial No. 470.791, fled February 28, 1983 and entitled "Improved Fluidic Transducer for Switching Fluid Flow", assigned to the assiqnee hereof. BACKGROUND AND BRIEF DESCRIPTION OF THE INVENTION In fuel management systems for internal combustion engines, on-board computers are currently supplied with data front sensors monitoring various engine operatinq parameters, such as rpm, temperature, exhaust gas characteristics, mass air flow through the air intake manifold. accelerator pedal position. etc., to determine the proper fuel-air ratio for fuel economy, smoothness of engine operations and compliance with emission standards. The electrical control signals are supplied to a solenoid controlled fuel inection valve which typically is biased closed by a spring so that a large electrical current is required to open the valve. In this example, while modern electronic computers and microprocessora have been developed to provide hiqhly accurate control siqnals for controlllnq liauid flow, the control devices per se have typically been a solenoid controlled mechanical valve which have difficulty in accurately tracking electrical signals and delivering short liquid pulses mainly because of their larqe pintle mass which is magnified in the case of springs biasing them closed. The leading edqe in particular of the liquid pulse delivered to the utilization system is not sharp. In the case of solenoid controlled fuel injectors for internal combustion engines. the output nozzles are very sensitive to fluid loadinq so that if a passageway to direct the output fuel pulse to a specific port intake target were attached, the performance is severely degraded. Reference is made to the article entitled Electronic Fuel Inection" by Rendolph, October 19 4. Popular Science, pages 73-75: Automotive Engineering, October l9R3, pages 40-45 and the phamplet "High Technology from Buick". "the 3.8 SF Turbo". Significant improvements in such systems have been provided in the above-identLfied related application of R.D. Stouffer wherein a bistable fluidic switch element with a crosa-over type interaction chamber leading to a common outlet and to a pair of output passageways, one of the output passageways leading to the enqine and the other leadinq to the supply tank. The bistable switch was reliably switched using a pair ot control ports which had control tubes coupled thereto and shaken in prescribed manner by a solenoid which, in turn. was controlled by the on-board computer or microprocessor. In the Stouffer system, individual fuel return from each injector Drovides for flushing of fuel vapor bubbles which might enter the fuel inlet. The conventional system described earlier herein (and described more fully hereafter) has no means for flushing out a vapor bubble once it has entered the i,nlet. This feature allows the bistable fluidic switch system to use a lower system fuel pressure (on the high pressure rail). Current systems (such as those marketed by Robert Bosch) use approximately 27 to 37 psi to avoid the formation of vapor bubbles. Lower pressure systems require less complexity and less expensive pump. An obect of the present invention is to provide an improved fuel inJection system of the type disclosed in the above-referenced Stouffer application. A further object of the invention is to provide improvements in fuel in,ection systems generally, particularly with respect to method and apparatus for improving the engine performance thereof. According to one maJor feature of the invention. a switch pin is proJected into and out of intrusion position in the flow path of fluid in the power nozzle of the fluidic element to cause switching in the chamber of the bistable switch. In other words. the use of side channels or control ports is eliminated and the fuel switching is accomplished solely by the interposition of a pin in the power nozzle thus simplifying the construction of the fluidic itself, eliminatinq small flow passaqes and the like and. at the same time. improving the response time, since there is no flow of fluid inside channels or delay involved in such flow. In a preferred embodiment. the axis of the power nozzle is canted relative to the axis of the chamber of the fluidic element so that in the absence of the pin, the switch is in one predetermined state and is switched form that state to the other state by pin intrusion and always returns to that predetermined state on removal of the intrusion pin. A second mayor feature of the invention is that air is supplied to each inJector at a point in the output flow passage leading to the engine so as to pre-air atomize the fuel before in3ection of same into the air intake manifold on the engine. This has the following advantages: A. It makes the flow calibration insensitive to changes in manifold vacuum - thereby eliminating the need to compensate the supply pressure for changes in manifold vacuum. B. It improves the quality of the fn¸l/air spray which is of primary importance in fuel/air mixture preparation. Improved spray (smaller droplets) and distribution in the air stream flowing in the air intake manifold results in a greater degree of fuel vaporization, yielding more complete combustion. The improvements is manifested by smoother engine idle and substantial minimization of idle shake". C. For improved cold/warm-up operation. air supplied to the inJectors may be selectively preheated, to improve early fuel vaporization characteristics. This technique is more effective than heating 100 percent of the combustion air during the first few minutes after a cold start < when very little heat is available) . Thus, improved warm-up exhaust emissions will result. D. Air supplied directly to the inJectors is accounted for by the engine control computer. When the air flow is computed based on the manifold absolute pressure, the in,lector air is accounted for bv its effect on manifold pressure. In o fuel mitering system which makes use of direct air mass flow neasurement, the source of injector air is downstream of the mass flow sensor. In either case, the source of injector air is derived from a source downstream of the combustion air filter. E. The injector air flows in proportion to the manifold vacuum (atmospheric pressure minus manifold absolute pressure) producing the best spray (smallest droplet size) under idle and light load conditions, when the vacuum is high - (15-20 in.hg.) and coincidentally, the engine combustion is most sensitive to droplet size at idle and light load conditions. F. Finally, the pin has a -low mass. The low mass electromechanical actuator allows the injector to turn on and off with less delay than conventional inJectors. This results in a flow calibration which maintains its linearity at Dulse widths below 2 msec. G. The introduction of air isolates the hlqh vacuum condition of the engine from the fluidic element. Air enters the engine output leg of the fluidic element so that particular point does not see the vacuum of the intake manifold. There is not enough air added to greatly effect engine vacuum. The power nozzle then becomes the manor source of pressure drop of the fluid in the system. In the preferred embodiment, both major features are utilized but it will be appreciated that either feature can be used independently of the other and still obtain advantages of the invention. Thus, the basic obJective of the invention is to provide an improved fuel inection system for internal combustion engines. A further object of the invention is to provide an improved bistable fluidic switch which has no control ports or passages; and a further obJect of the invention is to provide an improved fuel preparation by the addition of filtered and monitored air to fuel for internal combustion enqines prior to induction in the engine. BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, advantages and features of the invention will become more apparent when considered with the following specification and accompanying drawings wherein: Fiq. 1 ia a isometric view of a bistable fluidic switch according to-the invention, Fiq. 2a is an enlarged plan silhouette view of an actual operatinq unit with exemplary dimensions thereon, Fiq. 2b is a silhouette of Fig. 2 showings the flow path with the pin intruding or projecting position in a flow path in the power nozzle. Fig. 2c shows the flow paths with the pin in unintrudins or retracted position, Fiq. 3 is a schematic block diagram of a prior art (birch) fuel in,ection system which is currently commercially available, Fig. 4 is a fuel injection system incorporating the invention. DETAILED DESCRIPTION OF THE INVENTION Referrinq now to Figs. 1 and 2, the bistable fluidic switch 10 includes a body member 11 with a power nozzle 12 issuing fluid into chamber 13 formed with sidewalls 14 and 15 which diverge relative to the power nozzle and converqe relative to common outlet 16 leading to a first output passaqe 17 which conveys fuel to the engine and a second output passage 18 which conveys unused fuel to a return rail to the supply or tank. The bistable fluidic switch 10 has the exemplary silhouette shown in Fig. 2 and the flow paths which will be described more fully hereafter. Switch control pin or pintle 19 is moved through the transverse bore hole 20 by electromagnetic coil 21 which receives control signals from conventional on-board comDuter 22 which. in turn, receives a plurality of engine and Derformance data parameter signals on its inDut lines 23 from the various engine sensors and siqnal transducers (not shown*. A spring 24 biases the pintle or Din and its drivinq armature to a neutral or non-lntrudlng position. Passage 26 supclLes air from the air intake to air atomized fuel in outlet passage 17 and isolates the fluidic from the vacuum thus makinq the flow calibration insensitive to changes in manifold vacuum thereby eliminating the need to compensate the supply pressure for changes in manifold vacuum. It also improves the quality of fuel spray which is of primary importance in fuel/air mixture preparation. The improved spray results in smaller droplets to produce a greater degree of vaporization and hence. more complete combustion. This improvement is manifested by smoother engine idle. For improved cold/warm-up operation, air supplied to the injectors may be selectively preheated to improve early evaporation characteristics. Since this is relatively low volume of air is supplied to each of the injectors, it can be heated musing electric heater thermostatically controlled (not shown) in air rail line 98. This technique is more effective than heating 100 percent of the combustion air during the first few minutes after a cold start. It also results in improved warm-up exhaust emissions That is, the emissions are reduced. Moreover, the air supplied directly to the injectors is accounted for by the engine control computer 22. When the air flow is computed based on manifold absolute pressure. the injector is accounted for by its effect on manifold pressure. In a fuel meterinq system which makes use of direct air mass flow seasurement, the source of infect air is downstream of thehe mass air flow sensor and of the combustion air filter. Finally. the InJector air flow is in proportion to the manifold vacuum (atmospheric pressure minus manifold absolute pressure) thus producing the best spray pattern (smallest droplet size) under idle and light load conditions, when the vacuum is hlqh (15 - 20 inhJ). Coincidentally, the engine combustion is most sensitive to droplet size at idle and light load conditions. The pintle or pin 19 is of very low mass. Thus. this low nass electromechanical actuator allows the injector to turn on and off with less delay than conventional Bosch type injector. This results in a flow calibration which maintains its linearity at pulse widths below 2 msec. A cover 9 seals the bistable switch, the passages to the power nozzle 12, return fuel passages and fuel to engine passage are all sealed and secured to body member 11 for, in this embodiment, direct substitution in a conventional multi-point fuel injection. The air input 26 is connected to air rail 98 by short pipe section 99. As shown in Fiq. 2b, when the pin 19 is in an intrudinq position. it is specifically located in a reqion to the right of the center line through the power nozzle 12 and upstream of the theroad 12T of the power nozzle a short predetermined distance. It is essentially within this sector that the pin is most effective in effectinq a switch. The desiqn of the fluidic is such that in the normal case with the pin in non-intrudin position the axis of the power nozzle 12 is canted about 8 degrees relative to the axis of chamber 13 so that the fuel will flow through passage 18 and return to the tank (as shown in Fig. 2c). When the pin intrudes in.the flow pass in the power nozzle, it will cause 4 deflection of the et of 15 to 16 degrees. The chamber effectively amplifies this deflection to cause he ,et to travel along wall 15 and pass through common outlet 16 and be directed into outlet passage 17 leading to the engine, as shown in Fiq. 2b. As noted above, the bistable fluidic switch element has a chamber of the type wherein the sidewalls converge to a common outlet 16. The common outlet 16 with its converqinq sidewalls 13C and 14C isolate this chamber from the output channels 17 and 18 and the converging aidewalls qenerate vortices for maintaining the liquid flowing in the channels on one of the sidewalls until switched by operation of the pin. The awitchln element 1 bistable cr that it is in one arable state or the other which is maintained in that condition by the feedback constituted by the vortex 30 which is generated by a portion of the power stream which is peeled off by the opposite wall. Since the chamber is of the cross-over type, it serves to isolate the interaction region from pressures downstream of the throat or outlet. Referring now to Figs. 3 and 4. Fig. 3 illustrates diagrammatically a conventional fuel system treferred to in the art as the Bosch fuel injection system) in which a tank T delivers fuel via pump 50 through a fuel filter 51 to a fuel rail 52 which has the Pressure therein requlated by a compensated pressure regulator having a spring biased diaphram 54 defining the regulator chamber into two chambers, one side of which is coupled to the air intake manifold 60 by a compensating air pressure line 61. The fuel inJectors 70, 71 have a solenoid control injection valve which i8 typically biased closed by a spring so that a large electrical current is required to open the valve. The fuel management system for the internal combustion engine of the automobile includes an onboard computer which is supplied with data siqnals from sensors monitoring various engine operating parameters, such as rpm, temperature, exhaust gas characteristics, mass air flow, etc., an determines the proper fuel-air ratio for fuel economy, efficiency and smoothness of engine oDerations and compliance with emission standards. As diagrammatically illustrated, the computer 75 supplies individual signals to control each of the solenoids' 715, 72S of the injector 71 and 72, each of the inJectors having a relatively large mass pintle 71P and 72P, respectively. which are seated in a valve seat (not shown) by a spring 71S, 72S for the purpose of injecting fuel into the intake manifold induction pipe 60-1, 60-2 for each cylinder of the engine. It will be appreciated that while the Drior art system disclosed is for a conventional multi-point infection system, similar system is also used for sinqle point injection where a single injector is typically included and mounted in the body of the throttle (referred in the art as throttle bodv injection or TBI). The intake manifold 60 has e separate air induction pipe for each cylinder of the engine two of which are shown 60-1 and 60-2, each being provided with a separate fluidig injector which is connected in parallel to fuel supply or pipe rail 52. The same schematic applies to 4, 6 or 8 injectors Air is drawn through air filter 81 and passes through the mass flow sensor 82 to throttle 83. Throttle plate 84 is controlled by the operator and controls the flow area in the throttle air presage and thus the mass air flow to the engine cylinders via the induction pipes for each cylinder. The system incorporating the present invention is shown in Fig. 4 and includes the pump 50 for pumping fuel front the tank (not shown) through a filter 51 to a fuel rail 52 which supplies the fuel under pressure to each of the injectors 90, 91 which are fluidic fuel injectors having the silhouette illustrated diagrammatically in Fig. 1 with exemplary dimensions illustrated in Fiq. 2. Fuel under pressure in fuel rail line 52 is introduced into the power nozzle 12 from rail 52' for each of the fuel injectors and in parallel. Fuel which is not delivered to the engine is returned at a somewhat lower pressure to a return fuel rail 95 from each of the bistable fluidic injectors whenever the fuel is traveling on the side 14 of chamber 13 taking the path indicated by the arrow 96 (Fig. 2) arid is returned to the tank via line 97. A fixed pressure regulator 53' has a diaphrex 54' biasted by a spring 55' so as to maintain the fuel pressure at a relatively constant value. Air for aerating the fuel Drior to injection into the induction pipe leading to the engine is supplied after being filtered and measured by mass flow sensor but prior to passing through the throttle on fuel injector air supply rail 98 which supplies air in parallel to each of the fuel injectors and the outlet le or passaqe 17. The fixed pressure regulator 53' need not be compensated as in the case iilustrated in Fiq. 3. The above description relates to a sreterred exemplarv embodiment of the invention, it being understood that other embodiments and modifications thereof are possible within the spirit and scope of the invention as defined bv thehe claims appended hereto.

Claims: CLAIMS 1. In a fuel injection system for an internal combustion nine, aphid system having computer means for receiving a plurality of electrical signals corresponding to engine operating parameters and producinq electrical control signals for supplying fuel to said engine, a bistable fluidic switch having a power nozzle coupled to a supply of fuel under pressure, a chamber having sidewalls leading to a common outlet and a Dair of output channels receiving fuel issuing through said power nozzle, one of said channels leading to said internal combustion engine and the other of said channels leading to said supply, and electromagnetic means'controlled by said control signals from said computer means for controlling the state of said bistable aitch, the improvement comprising, a flow control pin controlled by said electromagnetic weans and positioned to be interposed in and removed by a fluid flow path in said Dower nozzle to switch the state of said bistable switch and change the one of said output channels in which fuel flows. 2. The fuel lnrector system defined in claim 1 Including means in the one of said output channels leading to said engine for isolating said fluidic switch from engine vacuum. 3. The fuel injector system defined in claim 1 including weans in one of said output channels for supplying air to air atomize the fuei flowina therein. 4. The fuel lnrector defined in claim 1 including means for assuring that in the absence of said pin in the flow path of fuel. said bistable element is in a predetermined one of its stable states to issue fuel into said other of said channels. 5. The fuel injector defined in claim 4 wherein the axis of said power nozzle is at an angle relative to the axis of said chamber. 6. The fuel injector system defined in claim 1 in which there is a fuel inJector for each cylinder of said engine, and a common fuel rail to each said bistable fluidic switch and a common fuel return rail connected to each said bistable switch. 7. In a fuel injector system for an internal combustion engine having an air intake manifold, said system having a computer means for receiving a plurality of electrical signals corresponding to selected engine performance parameters and producing electrical control siqnals for supDly of fuel to said engine, electromagnetically controlled fuel injector means controlled by control siqnals for receiving fuel under pressure from a supply and delivering a quantity of fuel to said engine according to said control signals. the improvement comprising. a short fuel passaqe coupling said fuel to the air intake manifold of said engine. a suDoly of air, and means for introducing said air in said short small fuel passaaewey to air atomize saib fuel before injection of same into said air intake manifold. 8. The fuel injector system defined in claim 7 wherein each said fuel injector includes a bistable fluidic switch. 9. The fuel injector defined in claim 8 wherein each said bistable fluidic switch includes: a power nozzle coupled to said supply of fuel, a chamber for receiving fuel from said power nozzle, a pair of output passages. each of which is adapted to receive fuel when said bistable fluidic outlet is in one or the other of its states. respectively. and means for switching the states of said bistable fluidic switch. 10. The fuel injector system defined in claim 9 wherein said means for switching includes a pin -movable into a position of intrusion in said power nozzle. a solenoid for controlling the position of said pin. and neans connectlnq said solenoid to said computer.

Inventors: CHESNUTIS, ERNEST W., JR., LESHNER, MICHAEL D.
Applicants: BOWLES FLUIDICS CORPORATION
Application year: 1986
Main classification: F15C1
IPC codes: F02M51, F02M69, F02D41, F15C1