US3587543A - Fluidic fuel injection with bistable valve - Google Patents

Abstract

A TIMED LOW-PRESSURE FUEL INJECTION SYSTEM OF THE TYPE INJECTING DISCRETE INTERMITTENT SQUIRTS OF FUEL AT SEVERAL LOWPRESSURE ENGINE LOCATIONS IN TIMED RELATION TO THE ROTATIONAL CYCLE OF AN INTERNAL COMBUSTION ENGINE. THE INVENTION IS PARTICULARLY CHARACTERIZED BY THE USE OF POSITIVELY DRIVEN BISTABLE FLUIDIC ELEMENTS TO PERFORM THE FUEL INJECTION FUNCTION AND TIMED PULSE GENERATNG MEANS TO DRIVE THE BISTABLE ELEMENTS TO THEIR INJECTING AND NONINJECTING OR OFF STATES.

Description

United States Patent [72] Inventor Janus: S. Sulich 2,918,911 12/1959 Guiot 123/32(E-1) Southfield, Mich. 3,366,370 1/1968 Rupert 123/119X 121] AppLNo. 847,597 3,389,894 6/1968 Binder..... 261/36 [22] Filed Aug.5, 1969 3,395,682 8/1968 Jackson... 123/139 [45] Patented June 28, 1971 3,487,820 l/l970 Clark....... 123/119 [73] Assignee The Bendix Corporation 3,501,099 3/1970 Benson 123/32(E) Primary Examiner- Laurence M. Goodridge [54] FLUDIC FUEL INJECTION WITH STABLE Att0meys William S. Thompson, Plante, Arens, Hartz, Hix

' VALVE and Smith 4 Claims, 5 Drawing Figs.

[52] U.S.Cl. [23/119,

23/140FG, 123/14QMQ261/36A ABSTRACT: A timed 1ow-pressure fuel injection system of [51] Int. Cl F02d 7/00 the type injecting discrete intermittent Squirts f f l at 0 Search everal low-pfes5u e engine locations in timed relation to the 0 l 261/36 rotational cycle of an internal combustion engine. The invention is particularly characterized by the use of positively [56] References (med driven bistable fluidic elements to perform the fuel injection UNITED STATES PATENTS function and timed pulse generating means to drive the bista- 2,077,259 4/1937 Planiol 123/32(E) ble elements to their injecting and noninjecting or off states.

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W381 g gpunu FLUIDIC FUEL INJECTION WITI-I BIS'IABLE VALVE BRIEF SUMMARY OF INVENTION Fuel injection devices which inject fuel at a plurality of locations and preferably at or in each engine cylinder produce nearly optimum fuel management with both good performance and the production of very low exhaust emissions. However, such systems tend to be complex, requiring means for initiating an injection at each cylinder at the proper time, computer and sensor means for determining the desired amount of fuel, a highly accurate injector valve at each cylinder injector location and associated fuel pressurizing and pumping means. The cost and complexity of such systems has retarded their acceptance even in the face, of clear performance advantages. Progress is being made with the aid of solid state and integrated circuit electronic elements in reducing the size and cost of pulse initiating and computer controls, but such devices have required in the past a number of expensive electronically actuated injection valves having highly optimized transient response times as the final control and injection determining element. Accordingly, it is an object of the present invention to provide an injection system utilizing lowcost fluidic elements as the fuel injector determining element.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a functional block diagram of a fuel injection system in which the features of the present invention may be most efficiently utilized.

FIG. 2 is a schematic diagram of a pulse determining and distribution network for producing time pulses at each injector location of a duration responsive to an input signal.

FIG. 3 represents a fluidic and mechanical sensing and computing circuit for generating an analogue control signal to be applied to the distribution device of FIG. 2.

FIGS. 4 and 5 show schematically two modifications of a portion of the pulse determining and distribution network.

DETAILED DESCRIPTION FIG. 1 represents in functional block form a fuel management system in which the novel features of my invention can be utilized. The system shown is particularly directed to an automotive engine control, but, as will be readily understood, could be applied to many other systems with only minor modifications within the scope of this invention.

The four blocks 10, I2, 14 and 16 forming the leftmost column in FIG. 1, represent the several input parameters derived from the engine and starting circuit and provide the intelligence from which the control system operates. As

labeled, the system utilizes manifold pressure 10, engine temperature 12, starting switch 14 (on/off) and engine speed 16 information respectively.

Sensor 18 represents a device which monitors manifold pressure (vacuum) and produces a usable fluid signal in the output passage 20 proportional to the manifold pressure over the full range of variations throughout all conditions of engine operation.

For an automotive engine, it is desired at or near wide open throttle conditions to enrich the fuel/air ratio for maximum power. At wide open throttle conditions, manifold vacuum decreases to its lowest value and begins to approach atmospheric pressure. Thus, manifold vacuum or pressure may be' utilized as a suitable parameter to indicate a wide-open throttle condition. In the block schematic, sensor 22 is termed the wide open throttle switch and senses manifold pressure to produce an output signal in passage 24 only during that portion in engine operation where power enrichment is desired.

Two engine temperature sensors are provided, one termed warmup sensor 26 and the other labeled cold-start enrichment sensor 28. Warmup sensor 26 provides a proportional signal in output passage 30 to control the degree of fuel enrichment required due to the cold engine condition. The sensor 28 senses temperature and is connected to the starting switch to provide an enrichment only during engine cranking at the beginning of a starting phase. During cranking, an output signal is produced in passage 32 when starting enrichment is required.

System sensors are completed with engine speed sensor 34 which produces in passage 36a signal proportional to engine speed. In the general case, the speed signal will not be usable in the form derived by sensor 34 and will require correction to a unique nonlinear function to satisfy the requirements of a particular engine and control system. Speed correction is, therefore, obtained by function generator 38-which produces in the output passage 40a corrected and usable speed signal.

All these sensor signals are supplied to a signal summer 42 which combines the signal to produce one output analogue control signal in output passage 44 representative of the desired amount of fuel at each instant of time it is desired to deliver to the engine.

The fuel demand signal transmitted by passage 44 is received by a distributor device 46 which distributes discrete intermittent fuel pulses to each engine mounted injector symbolically indicated by the horizontal lines designated by numeral 48. The distributor 46 also performs the functions of determining the timing of the pulse and is duration responsive to the command signal supplied by passage 44.

Referring now to FIG. 2, the distributor and pulse determining network is shown in functional detail and is designated by numeral 46. It is operative with a bank of six fluidic injectors designated by numeral 48 and receives a demand signal designated by numeral 44. Six injectors are shown by way of example as any number may be used in the practice of my invention. By Fluidic" is meant that class of devices growing out of the technology wherein sensing, control, information processing, and/or actuation functions are performed solely through the use offluid dynamic phenomena," as quoted from Fluidic Systems Design Guide First Edition, 1966, Appendix C Page 147.

. Each of the fluidic injector valves 480 through 48f respectively, are comprised of a bistable fluidic element, for example, of the types described in U.S. Pats. Nos. 3,396,619 or 3,425,430.

Fuel at a regulated pressure is supplied to the power jet passages designated by numerals 50a through 50f respectively at a regulated constant pressure. Confining the discussion to bistable fluidic element 48a, pressurized fluid is ejected by power jet nozzle 52a into a region communicating with an apex of two outlet passages 54a and 56a so as to deliver fuel into either one or the other of the outlet delivery passages. Passage 540 may be considered a return passage to the fuel storage or tank member. Outlet passage 56a would preferably eject fuel into the intake manifold or engine block immediately upstream of the cylinder or intake valve to provide a point of injection close to the cylinder, but nevertheless, in a lowpressure region. The dashed horizontal lines on each output passage 54a and 56a are symbolic representations of wall attachment phenomena more fully disclosed in the beforementioned U.S. Pat. No. 3,396,619 and often referred to as the Coanda effect" after Henri Coanda who described the principle in U.S. Pat. No. 2,052,869. It should be borne in mind that The wall attachment phenomena is but one means to achieve a bistable fluidic element which also may be accomplished, for example, by the use of feedback passages as described in U.S. Pat. No. 3,425,430. The effect of the wall attachment phenomena is that the control fluid stream issuing from power nozzle 52a will seek either passage 54a or 56a, but not both concurrently. That is, it will tend to switch between one or the other in a bistable manner. The fluid issuing out of passage 56a for example, would attach itself to a sidewall and continue to issue from this outlet passage until positively switched by a control signal.

Fuel is also taken from supply port 50a and transmitted through orifices 58a and 60a to control passages 62a and 64a respectively. The control passages 62a and 64a connect with control jets 66a and 68a respectively, which eject fluid within the fluidic element transversely to the main power jot 52a producing a control force operative to switch the main fluid beam between the passages 54a and 56a. Control passage 62a is connected to a ring manifold 70 and terminates in an opening 720 which is arranged circumferentially in a sequential order with similar openings 72b through 72f. Openings 72a, 72b, 72c, 72d and 722 as illustrated in the drawing are all vented to a low-pressure area providing a low-pressure control fluid in conduits 62a and 62f respectively. Opening 72f is, however, covered by a projection 74 formed on rotating cam 76. Cam 76 may, for reference purposes, be termed a start-ofinjection cam. As passage 72f is closed, pressure in passage 62f sharply increases forming a control pulse at control jet 66f which deflects the main fluid stream out of outlet passage 56f. Control jet passages 64a through 64f are connected to manifold ring 78 in a circumferentially arranged manner terminating with orifices 80a through 80f respectively. End-of-injection detennining cam 82, with projection 84 formed thereon, is operative to sequentially close openings 80a through 80fin the same manner as projection '74 of cam 76. In fact, cams 76 and 82 may be formed integrally or be extensions of one another. As projection 84 closes opening 80f, a control pulse appears in passage 64f and also at control jet 68f switching the main power jet to return passage 54f thus terminating the injection at injector 48f. The phase relationship between cams 76 and 82 respectively determines the time duration of injection at an injector valve. Manifold ring 78 is rotatable to a small degree to alter the phase relationship and thus the duration of injection to meet the various fuel demands of the system. Bellows 86 and 88 are arranged in opposing relationship and connected to rod 90 to position manifold 78 a small angular degree in response to a differential pressure signal applied via passage 92 and 94 to the bellows. The differential pressure signal to passages 92 and 94 is supplied by the signal summer 42 illustrated in the block diagram of FIG. 1. Hydraulic, mechanical, electrical, pneumatic or fluidic signal generating means maybe used to position the manifoldring 78 in response to a demand flue signal. It is noted at this point that to combine certain electronic and fluidic techniques may provide an optimum fuel injection system. Engine intelligence may be combined and computed in a very compact electronic system or computer and then applied to a fluidic fuel distribution system such as illustrated in FIG. 2 to avoid the complexity and cost of solenoid operated injection valves.

In the case shown, fluidic injection at each engine cylinder has a discrete time of injection which occurs at the optimum point in the firing cycle at each engine cylinder. Thus, the

system is capable of accomplishing fully timed fuel injection for all cylinders. To obtain control simplicity or provide greater available pulse time, simpler systems have been suggested in the electronic art of injecting simultaneously to a group or all of the cylinders without substantially degrading engine performance. Simultaneous or grouped injection may, of course, be readily accomplished by the-present system simply by actuating the start-of-injection control signals to more than one of the fluidic injectors simultaneously. FIGS. 4 and show passage arrangements as would be used for twogroup and simultaneous fuel injection systems respectively. Illustrated portions of FIGS. 4 and 5 correspond to that illustrated in FIG. 2 andbear the same identifying numerals.

Referring now to FIG. 3, a system for sensing, computing and deriving an analogue fuel demand signal is shown. The various elements have the same numerals assigned to them in the block diagram of FIG. I. A rotative signal indicative of engine speed 16 is supplied to shaft 102 which rotates disc 104 of vortex type fluid in sensor 34. Rotation'of disc 104 causes an addition of tangential momentum to the source flow, supplied from source 106, such that a vortex action occurs resulting in a variation of the signal in transmitting passage 36, proportional to the speed of disc 104. Pressurized control fluid, supplied from source 106, is used to preset the sensitivity of the vortex speed sensor 34. The principles are more fully described in U.S. Pat. No. 3,347,103 issued Oct. 17, 1967 which describes a similar speed sensor. Excess fluid which is not utilized in the signal transmitting passage 36 is collected in the receiving chamber and returned to a supply tank. The fluid speed signal is transmitted to function generator 38, which contains a movable piston 112 and return bias spring 114, which urges the piston in opposition to the fluid speed signal pressure applied to chamber 116. Movable piston 112 contains a center land 118 having a profiled or contoured opening 120 which is in the path of the flow of supply fluid from inlet passage 122 to outlet passage 40 to provide a unique function which may be controlled by proper shaping of the orifice 120. It is anticipated that a speed correction may be implemented by proper profiling of the orifice 120. Most engines usually require some form of correction with speed because of changes of engine volumetric efficiency and varying air flow dynamic corrections. This correction is empirical for a specific engine and is usually nonlinear.

Manifold vacuum is supplied to receiving passage 10 and transmitted to sensor 18 which consists of an evacuated bellows 124i operative to position a movable orifice 126 on tube 128 which controls the supply of fluid from a supply source 130 to outlet passage 20. The fluid pressure in passage 20 will vary in value with all variations of manifold vacuum. Manifold vacuum is also transmitted to wide open throttle sensor 22 which is a monostable fluidic element having its stable flow out output leg 132. Regulated power fluid is supplied from power jet 134, and in the absence of control signals, would attach itself to the wall of output passage 132. Control jets 136 and 138 are provided which are vented to the atmosphere and connected to the manifold vacuum source respectively. For most part throttle and idle throttle conditions, manifold vacuum at control jet 1.38 is sufficiently high to overcome the wall attachment phenomena in passage 132 and switch the control jet out vent passage 140. As wide open throttle condition is approached, manifold vacuum decreases to the point where it is incapable of maintaining the power stream deflected out of its unstable port 140 and the power stream begins to deflect and be received in outlet passage 132 where it is operative over a selected range to produce a signal in outlet passage 24.

An enrichment signal is provided for correcting fuel/air ratio during cold engine starting. Regulated fluid supply pressure is supplied to passage 142 and is conveyed by transmitting passage 144 to the normally closed solenoid operated valve 146. Electrical leads M8 and to the solenoid 152 are in the circuit containing the starter switch and would apply energizing potential during the period that the automotive starter switch is depressed. Energization of the solenoid 152 opens valve 146 permitting a control signal to be transmitted to outlet passage 32 when cold start enrichment is required.

Bimetallic temperature sensing rod 154 is in a location to sense engine temperature. Rod 162 is attached to bimetallic rod 154 and controls the variable orifice 184 to provide cold start enrichment proportional to engine temperature. Should the engine be hot prior to cranking, bimetallic rod 154 will cause orifice 184 to be closed so'that no fuel enrichment is provided during cranking when the engine is hot. For engine unloading during start, that is clearing out a flooded engine, rod 156 is connected to the air throttle valve so that at wide open throttle, switch 158 is open and solenoid valve 152 for cold start enrichment remains closed and there is no signal in line 32.

It is also desired to have temperature correction of the fuel ratio during engine running. A proportional control valve 160 having a variable orifice, generally designated by the arrow, is controlled by the rod 162 also attached to the temperature sensor 154. The pressure supplied to warm up sensor 26 is thus varied proportionately with temperature. A speed signal is applied to control jet 164 of the fluidic element 26 to provide a speed corrected temperature signal to the output passage 30. The speed signal proportionately reduces the degree of enrichment increasing engine speed. The various processed signals contained in each of the output passages 20,

24, 30, 32, and 40 are each divided into a pair of branch passages bearing the 'same numeral but with subscripts a and b respectively. These signals are supplied as two control inputs to the signal summer 42. Signal summer 42 consists of two fluidic vortex elements designated by numerals 42a and 42b respectively which receive a power fluid stream from a common source 170 through branch passages 172 and 174 respectively and power jets 176 and 178 which inject transversely into a circular vortex changer. Fluid is also supplied to control jets 180 and 182 to provide a clockwise vortex fluid flow within the element 420 and a counterclockwise vortex flow within the element 42b. Vortex element 42a receives control signals from passages 40a, a, 24a, and 300 which are arranged to inject control signals tangentially into the vortex chamber in a direction aiding the flow established by control jet 180. in vortex fluidic element 42b, the control jet signals from the control passages 40b, 20b, 24b, b, and 32b, inject signals into the vortex chamber in a direction opposing the direction the vortex flow established by control jet 182. The two vortex control elements 42a and 42b are thus arranged in pull-push relationship amplifying signal changes in the output passages 44a and 44b respectively which are then transmitted to bellows 86 and 88 previously described; The arrangement of two vortex amplifiers minimizes the effects of the pressure variations at the supply 170 as these effects are balanced out and neutralized. In operation, the sensor computing and summing circuit illustrated in FIG. 3 gives a fuel demand signal for all engine conditions including the starting, idle warmup, part throttle and wide open throttle conditions. Referring back to the distributor device of H6. 2, the fuel demand signal is used to rotate the manifold 78 altering the relationship between the start of injection signal and the end of injection signal. As will be apparent, an intermittent flue injection system without solenoid injection valves has been obtained.

lclaim:

l. A fuel injection system for an internal combustion engine having an air intake passage and at least one cylinder, said fuel injection system comprising:

a bistable fluidic injector valve arranged to inject fuel into a low-pressure region upstream of an associated engine cylinder;

a fuel supply source for supplying fuel to the bistable fluidic injector which is diverted to one passage during an inject state and to a return passage during the off state of the fluidic injector;

means driven in relation to engine speed operative to generate a first start of injection control signal and a second end of injection control signal, said means being connected to the fluidic injector valve so that said control signals are operative to switch said fluidic injector from the off to the inject state and from the inject to the off state in response to the start of injection and end of injection control signals respectively;

control means determining engine fuel requirements operatively connected to said last named means to control the time duration between start and end of injection signals.

2. A fuel injection system for multicylinder internal combustion engines comprising:

a plurality of bistable fluidic injector valves, one for each engine cylinder arranged to inject into a low-pressure region upstream of its associated cylinder;

a fuel supply source for supplying fuel to each injector;

a pair of control jets for each injector to supply start of injection and an end of injection control signals respectivey;

first means driven in relationship to engine speed connected to one of said pair of control jets to provide a control signal operative to switch said bistable fluid injectors to the inject state in timed relationship with an engine operating cycle;

second means driven in relationship to engine speed connected to the other of said pair of control jets to provide a control signal operative to subsequently switch said bistable fluid injectors to the off state; means responsive to engine fuel demand operatively connected to said second means to control the time duration said bistable fluidic elements are in the inject state.

3. A fuel injection system as claimed in claim 2 wherein:

said first and second means comprise a pair of cams adapted to be rotatively driven in proportion to engine crank shaft speed.

4. A fuel injection system as claimed in claim 3 wherein:

each of said first and second means includes an associated annular manifold with annually arranged control ports for each fluidic injector arranged sequentially in injector firing order sequence, said cams and control ports cooperative to generate start of injection and end of injection control pulse respectively.

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