US3728989A

US3728989A - Control system for the injection of fuel into internal combustion engines

Info

Publication number: US3728989A
Application number: US00135963A
Authority: US
Inventors: L Monpetit; J Schneider; J Jourde; J Ufnaleski; P Advenier; G Sallot
Original assignee: Societe des Procedes Modernes dInjection SOPROMI
Current assignee: Societe des Procedes Modernes dInjection SOPROMI
Priority date: 1970-04-22
Filing date: 1971-04-21
Publication date: 1973-04-24
Anticipated expiration: 1990-04-24
Also published as: ZA712133B; SE368261B; DE2119429A1; GB1308731A; JPS5434857B1; FR2088701A5

Abstract

In order to obtain constancy of throughput for the different injectors of an internal combustion engine, the valve is inserted between a supply of fuel and the mechanical injectors is a three way valve connected respectively with the output of the supply, with the injectors possibly through a sequential distributor and with a return to the supply. An electromagnet controlled by electric signals attracts a piston normally connecting the supply output with the return to the supply so as to connect during the desired period the supply output with the injector systems. The three ways of furthermore transiently interconnected at the beginning and at the end of each energization, so as to prevent excess pressure.

Description

United States Patent Monpetit et al. 51 Apr. 24, 1973 [541 CONTROL SYSTEM FOR THE [56] References Cited KNJECTKON OF FUEL INTO INTERNAL S COMBUSTION ENGINES UNlTED TATES PATENTS [75] Inventors: Louis A. Monpetit, L Etang la Ville; g" ?y----{- -i --l23/I39 E Jurg Schneider; Herve Gueret 3 516 395 6/1970 aim I. of Versallles; Adveme"! 3,490,425 1/1970 Bassotetal ..123/139 R Pans; Georges R. Sallot, Elizabethville; Jean-Pierre Paul Assignee:

Filed:

Appl. No.:

Jourde, Villennes S/Sienne; J. W. Ufnaleski, Mantes la Ville, all of France Societe Des Procedes Modemes Dlnjection Sopromi, Les Mureaux, France Apr. 21, 1971 Foreign Application Priority Data 123/139 R, 139 AM, 139 E Primary Examiner-Laurence M. Goodridge Attorney-Kenyon & Kenyon Reilly Carr & Chapin [5 7 ABSTRACT In order to obtain constancy of throughput for the different injectors of an internal combustion engine, the valve is inserted between a supply of fuel and the mechanical injectors is a three way valve connected respectively with the output of the supply, with the injectors possibly through a sequential distributor and with a return to the supply. An electromagnet controlled by electric signals attracts a piston normally connecting the supply output with the return to the supply so as to connect during the desired period the supply output with the injector systems. The three ways of furthermore transiently interconnected at the beginning and at the end of each energization, so as to prevent excess pressure.

10 Claims, 3 Drawing Figures PATENTEDAFRZMUB 7 3,728,989

SHEH 3 OF 3 L. MONPETIT HGUE/QET J. P. JOURDE 5. SHLLOT d. SCHNEIDER J.YUFNAL.EWSKI F? ADV NIER,

CONTROL SYSTEM FOR THE lNJECTlON OF FUEL llNTO INTERNAL COMBUSTION ENGINES The present invention has for its object a fuel injecting system for internal combustion engines. It has already been proposed in this field of application to control the injection by means of electromagnetically controlled injectors located in the immediate vicinity of and on the upstream side of the admission valves in the case of an indirect injection and directly into the engine cylinder head in the case of a direct injection. Each electromagnetic injector portions out the fuel into the corresponding cylinder upon receipt of an electric controlling signal the duration of which is defined by conventional electronic means governed by the operative parameters of the engine.

Whereas there is no great difficulty in the production of an electric controlling signal corresponding to the actual requirements of the engine, it is a very difficult matter to obtain an amount of injected fuel which remains identical for a given injector and for a given signal. As a matter of fact, the allowances in size in the manufacture of the injector lead to modifications in the path of the injector needle and in the cross-sectional area afforded for the passage of fuel and also to modifications in the magnetic properties and consequently each set of injectors intended for use with a same engine must be gauged, and the injectors for use with a same engine must be gauged, and the injectors must be adjusted by suitable means with a view to obtaining characteristic properties very near one another for the different injectors, the accuracy required approximating 1 percent.

It has already been proposed to remove these drawbacks by resorting to a single electromagnetic measuring valve connected with simple mechanical injectors, either directly or with the interposition of a rotary distributor providing for sequential injectors following the sequence ofignitions.

However, this solution was not satisfactory since the uniform distribution of the throughput between the mechanical injectors was not properly ensured in the case of a direct connection without'any intermediate distributor. Furthermore, the injection was performed under unfavorable conditions since the pipes leading from the measuring valves to the injectors remained subjected to pressure after the closing of the measuring valve, which resulted in uncontrolled leaks through the injectors.

The present invention has for its object to cut out these drawbacks and it covers an injection controllay system feeding fuel directly or inderectly into internal combustion engines. According to the invention, an electromagnetic measuring valve adapted to receive an electric signal of a duration varying with the operative conditions of the engine is inserted between a supply of fuel under pressure and mechanical injectors of the flap valve or needle type as well known in the art. The novelty of the invention resides in that the measuring valve is a three-way valve of which one way is connected with the supply of fuel under pressure, the second way is connected with the mechanical injectors directly or through the agency of a sequential distributor and the third way is connected with a fuel-returning channel which is kept under a pressure lower than the gauged pressure of the injectors, said measuring valve being designed in a manner such that the three ways are interconnected each time an electric signal begins or ends its actuation.

According to further developments of this inventive idea, various other improvements are possible, to wit the member closing the three-way valve is constituted by a hollow annular piston sliding between two extreme positions inside the valve body in which it is guided fluid-tightly, said position being provided with a terminal ridge cooperating for one extreme position of the piston with a frustoconical seat formed in the valve body while the fuel under pressure is fed into an annular space extending between said frustoconical seat and the surface guiding the piston inside the valve body and the output of the fuel towards the injectors starts from a bore extending axially of the frusto-conical seat, the end of the piston opposed to its terminal ridge being rigid with the movable armature of the controlling electromagnet and being provided with a second ridge cooperating for the other extreme position of the piston with a second frustoconical seat, the inside of the piston being connected with the output leading to the injectors and the annular space between the second frustoconical seat and the body of the measuring valve opening into the fuel-returning channel;

the diameters of the annular piston and of the ridges thereon are selected so as to provide a complete or substantially complete hydraulic balance for the piston;

the second frustoconical seat is rigid with a cylindrical member slidingly carried inside the piston and acting as a bearing for one end of a return spring with the interposition of an adjusting screw, while the other end of the return spring rests on a dished part rigid with the piston;

the valve body rests on a flanged support the central section of which is recessed so as to be connected with the supply of fuel said recess being closed by a diaphragm the peripheral edge of which is held fast by a cover screwed onto the flanged support with the interposition of a spring blade between the diaphragm and the cover, so that the space defined by the recessed section and the diaphragm forms a hydraulic pressure accumulator;

the support carrying the valve body includes a flange provided with recesses housing as many electromagnets as there are injectors, said electromagnets registering with corresponding output connections formed in a detachable cover while their disc-shaped cooperating electromagnets and output connections in the recesses connected with the inside of the piston of the measuring valve and forming a sequential distributor;

the stationary electromagnet armature or armatures forms a tore-shaped member of ferromagnetic material, the cross section of which is that of an inverted U, said member housing the energizing winding, said tore being slotted radially so as to cut off the eddy currents and being housed in its turn in a part rigid with the valve body with the interposition of a sheet of insulating material and/or a fuel-filled gap;

the parts in which the stationary and movable parts are housed are subjected to a truing along their cooperating surfaces and the position of the parts when assembled and maximum and residual gap widths are adjusted by means of shims inserted between the surfaces registering with each other and also underneath the abutments defining the ends of the piston stroke.

By way of example and in order to further the understanding of the following description of an embodiment of the invention, reference shall be made to the accompanying drawings whereof:

FIG. 1 is a diagrammatic view of an injection plant according to the invention.

FIG. 2 is a diagrammatic sectional view of a measuring valve provided with an accumulator of fluid pressure.

FIG. 3 is a diagrammatic sectional view of a measuring valve provided with a sequential electromagnetic distributor.

Turning to FIG. 1, it is apparent that the engine 1 includes an input manifold 51 associated with the individual pipes opening into the different engine cylinders through conventional mechanical injectors, return flap valves or a needle valve. The fuel is sucked out of the container 46 by the pump 50 and delivered into the threeway electromagnetic measuring valve 3 through the filter 49. The excess fuel returns into the container 46 under control of a pressure regulator 48 while a pressure accumulator 47 which may, if required, form a unit with the measuring valve 3 is also provided. The measuring valve is connected with an input channel 3a, with a liquid output channel wherein the liquid is subjected to a modulated pressure 3b leading to the injectors 4 either directly or else through a sequential distributor 9 which may be controlled mechanically. A pulse transmitter 2 controlled by the rotation of the engine is adapted to release the electronic system 5 producing the signal controlling the measuring valve 3 and actuating the distributor 9 to define sequentially the operation of the injectors. Said electronic system 5 produces, as well-known in the art, an electric signal under control of the operative conditions of the engine, said signal adjusting the amount of fuel to be injected by adjusting the duration of the opening periods of the channels 3a and 3b controlled by the measuring valve 3. Obviously, the injectors may be designed in a manner such that they provide a direct injection into the combustion chamber of the engine instead of resorting to an indirect injection as in the case illustrated, this modification remaining within the scope of the invention. Electric energy is fed to the electronic system 5 by the supply 53 under control of the switch 52.

Turning now more particularly to FIG. 2, it is'apparent that the measuring valve 3 is associated with the hydraulic accumulator 47 and forms a unit therewith. The body 6 of the measuring valve includes a connection for the channel 3a feeding liquid under pressure and opening into a recess 6f formed in the pedestal or flanged support 61' and it also includes connections for the fuel output channel 3b leading to the injectors, only one of last mentioned connections being illustrated. The connection for the channel 30 returning the liquid towards the container forms part of an upper section 7 rigidly secured to the valve body 6 by the flanged nut 9. Said upper section 9 encloses the electromagnet 12-13 controlling the movements of the annular piston 10. Said

electromagnet

12, 13 of an annular shape includes a stationary armature, the cross-section of which is in the shape of an inverted U. The winding 13 is housed inside the U-shaped armature and is connected with two terminalsl4 fitted in said upper member through the agency of an insulating ring 15. It should be remarked that with such an arrangement the eddy currents which may arise in the stationary armature cannot flow along a circular path since they are interrupted by one or more radial slots not illustrated which are formed in said stationary armature I2. In order to further cut off any eddy currents, the stationary armature 12 is also carefully insulated with reference to the upper section 7 which is made of an amagnetic material by an insulating sheet 30 illustrated in interrupted lines and by an annular slot 7b which is filled with fuel and serves as a return passageway for the leaks towards the connection 30 through the intermediate oblique bore 70. After the

electromagnet

12, 13 has been positioned inside the upper section 7, the surface registering with the valve body 6 are subjected to a truing along a transverse plane.

The

electromagnet

12, 13 controls the movement of the annular piston 10 which is provided for this purpose with the movable armature 21 which is rigidly secured to the piston as provided by folding back its edge 21a over a corresponding shoulder of the piston. The annular piston 10 slides fluidtightly between two extreme positions inside the body 6. Fluidtightness is ensured either by means of a fluidtight packing 16 as illustrated or else by means of a balanced assembly with a very narrow clearance. The stroke of the piston 10 between its extreme positions is limited by the frustoconical sealing surfaces 6a on the body 6 and 11b on the cylindrical inner guiding sleeve-shaped member 11 respectively, while the maximum gap corresponding to the contact between the sealing ridge 10b and the frustoconical sealing surface 60 is adjusted by a shim 28 inserted between 'the upper section 7 and the body 6 whereas the minimum or residual gap corresponding to the contact between the sealing ridge 10a and the frustoconical sealing surface 11b is similarly adjusted by another shim 2 inserted between the upper section 7 and the guiding member 11. To this end the upper surfaces of the body 6 and of the movable armature 21 and also of the guiding member 11 are subjected to a truing in a transverse plane. Through such a simple machining and assembling, all difficulties as to the machining allowances for the different parts are cut out. By way of exemplification it may be mentioned that the maximum gap is of a magnitude of 0.05mm, the stroke of the piston being thus equal to about 0. lOmm.

It is apparent that the hollow cylindrical member 11 slidingly engages the annular piston 10 and is carried by it through the return spring 19 which rests on the dished member 17 secured by an annulus 18 to the inner surface of the piston while the other end of the spring 19 bears against a shoulder 20b provided on the adjusting screw 20 screwed into the head of the guiding member 1 The adjustment of the tensioning of the spring 19 may be performed after the measuring valve has been assembled, by introducing a tubular wrench into the reccessed end 11a of the guiding member 11 while a screw driver is introduced into the slot 20a of the screw 20 so as to make the latter turn in the direction required for adjustment. When the piston is in the position illustrated without the electromagnet being energized, the output connection 3b communicates with the return connection 3c through the oblique bore 6g, the central bore 6e, the inside of the annular piston 10 and of the inner cylindrical member, the clearance 60, the clearance 7b and the oblique bore 7a, so that the injectors are subjected to a low pressure which may be equal to atmospheric pressure or to say 2 to 3 bars in order to prevent the formation of vapor bubbles in the circuit under the action of the temperatures developed during operation Such a counter-pressure should however be lower than the gauged pressure in registry with the injectors.

When the

electromagnet

12, 13 is energized, the movable armature 21 is attracted upwardly and the sealing ridge a on the annular piston 10 engages the frustoconical surface 11b whereby the communication between the central bore 62 in the valve body and the return connection 3e is cut off whereas the connection 30 feeding fuel under pressure communicates with the output connection 3b and thereby with the injector system through the recess 6f formed in the flanged pedestal 61' of the valve body 6, the oblique bore 6d in said body, the annular space 6b surrounding the lower end of the now raised piston, the passage thus afforded between the sealing ridge 10b and the cooperating surface 6a, the central bore 62 in the valve body and'the oblique bore 6g.

Thus, it appears that the injectors receive suddenly liquid under pressure when the electromagnet is energized and this produces an injection during the period of energization of the electromagnet after which, the electromagnet being deenergized, the pressure returns speedily to its original value which produces a clean and quick closing of the injectors; this ensures identity between the throughputs in the different injectors, even if said injectors are to operate simultaneously for each pressure surge. It should be remarked that this particularly remarkable result is achieved'by providing an in terconnection between all three

connections

3a, 3b, 30 at the beginning and at the end of each energization of the

electromagnet

12, 13 when the passage between the lower sealing ridge 10b and the frustoconical sealing surface 6a is already open, while the passage between the upper sealing ridge 10a and the cooperating sealing surface 11b is not yet closed.

In order to maintain the minimum magnetic stress simultaneously with a very short delay for the response of the measuring valve, the piston 10 is entirely balanced or substantially so for all the positions assumed by it, provided substantial equality is obtained between the diameters of the upper and lower sealing ridges 10a and 10b on the piston 10. 7

It should be remarked furthermore that the hydraulic accumulator 47 forming a unit with the measuring valve 3 is constituted merely by the recess 6f in the flanged pedestal 61 which recess is closed by the double diaphragm 23 clamped against said flange 6i by the cover'8 engaged by the screws 27. A spring blade 25 urges the diaphragm 23 upwardly through the agency of the supporting plate 24 secured to the diaphragm by the central nut and screw system 26. The bore 6e in the f valve body at the end facing 47 is closed by a plug 22,

so that the accumulator communicates only with the input connection 3a when the measuring valve is inoperative. Y

Said valve is illustrated at a scale 2:1 and its capacity appears thus as quite remarkable.

FIG. 3 illustrates a measuring valve intended chiefly for Diesel engines. Since Diesel engines are of the direct injection type and require therefore sequential injection, said measuring valve incorporates an electromagnetic sequential distributor forming a unit with it. The actual measuring part of the valve is practically identical with that illustrated in FIG. 2 and similar elements carry the same reference numbers. For sake of an easier machining the piston 2 and the hollow cylindrical guiding member 11 are housed in an independent part fitted in the valve body 6.

Fluidtightness is ensured between this inserted part and the body 6 by tore-shaped

packings

31, 32. The valve body is provided with radial bore 611 connecting the annular clearance 6b between said insert part and the piston with the annular chamber 5'b between the latter and the actual valve body 6'; which chamber 6'12 communicates in its turn through a bore 6a with the connection 3a feeding fuel under pressure. On the other hand, the central bore 6e is alined with a bore 3b opening into a central recess 28'a. The sequential distributor is constituted by electromagnets including a stationary armature 12 and a winding 13 cooperating with a disc-shaped movable armature 21. The electromagnets are executed in a manner similar to the

electromagnets

12,13 of the measuring valve. In other words, they are fitted in their housings with the interposition of an insulating sheet 30' along their periphery while a plug 11, of an amagnetic material is first inserted before the shim 29' to allow a truing of the flat lower surface of the valve body 6'. The winding 13 is connected withthe terminals 14' protected by their insulating sheaths 15. The movable armature 21 is housed in a recess in the disc 28 communicating with the central recess 28'a. Said movable armature 21 is provided with a fluidtight packing 37, so that the connection 3b is cut off from the central recess 28'a when the movable armature is at rest and is not attracted upwardly by the energization of the electromagnet. The maximum gap is defined by the difference in thickness between the disc 28' and the movable armature 21 whereas the residual gap is defined by the shim 29. A tore-shaped fluidtight packing 36 is providedround the plug 11' which encloses a return spring 19' within an inner recess. The tore-shaped packings 35 ensure fluidtightness between the central recess 28a and the external atmosphere while a centering sleeve 34 is provided for the positioning of the cover 8 carrying the disc 28' with reference to the flanged pedestal 61' of the valve body.

The

electromagnets

12, 13 may be executed very simply and their bulk may be small since they are energized only outside the injection periods and have therefore to exert a very slight effort in order to merely attract the movable armature 21' since no difference in pressure acts on said movable armature at the moment of the opening and closing of the entrance of the connection 3b. Thus, even in the case where the measuring valve 3 is associated with an electromagnetic sequential distributor 9, the arrangement is extremely simple and compact, so that it may be executed at a comparatively low cost price.

What we claim is 1. In a fuel injection system for internal combustion engines of the type that includes a container of fuel,

means for supplying fuel under pressure from the container, a fuel injector associated with each combustion space of the engine, means for producing intermittent electric signals synchronized with engine rotation and of a duration depending on the operative conditions of the engine, and a three-way metering valve having an inlet connected to the means for supplying fuel under pressure, a first outlet connected to the fuel injectors, a second outlet connected to a low pressure return line to the fuel container, and means for actuating the valve intermittently in response to the electric signals to supply variable quantities of fuel to the injectors as a function of the duration of each signal, the improvement wherein the metering valve comprises:

a valve body having an internal chamber;

a first annular valve seat in the chamber;

a second annular valve seat in the chamber, spaced from and facing the first seat;

a first passageway opening into the chamber adjacent the outer circumference of the first seat and communicating with the valve inlet;

a second passageway opening into the chamber adjacent the inner circumference of the first seat and communicating with the first outlet of the valve;

a third passageway opening into the chamber adjacentthe outer circumference of the second seat and communicating with the second outlet of the valve; and

a valve member mounted in fluid-tight relation to the chamber wall between the openings of the first and third passageways for movement by the actuating means from a first position to a second position in response to the electric signals, the valve member having first and second oppositely-facing circular contact surfaces for sealing engagement respectively with the first valve seat when in the first position and with the second valve seat when in the second position, and the valve member further having a passageway joining the inner sides of the first and second circular contact surfaces, whereby the valve member when in the first position permits communication only between the second and third passageway, when in the second position permits communication only between the first and second passageways, and when intermediate the first and second positions permits communication between all three passageways.

2. The fuel injection system of claim 1 wherein the valve actuating means comprises:

an electromagnetic actuator connected to the valve member for moving the member from the first to the second position atthe commencement of each of the electric signals and I a biasing means for returning the valve member to the first position at the termination of each of the electric signals.

3. The fuel injection system of claim 2 wherein the valve chamber comprises a cylinder, thefirst and second valve seats comprise frusto-conical surfaces at opposite ends of the chamber, and-the valve member comprises a tubular piston mounted for fluid-tight sliding engagement with the wall of the cylindrical chamber between the openings of the first and third passageways.

4. The fuel injection system of claim 3 wherein the first frusto-conical valve seat is concave; the first circular contact surface of the valve member comprises an outward-facing edge formed by the intersection of the exterior surface of the tubular valve member with the end surface of the valve that faces the first seat; and the first and second contact surfaces have approximately equal diameters, whereby the hydrostatic forces on the valve member are substantially balanced.

5. The fuel injection system of claim 4 wherein the second frusto-conical valve seat is convex; the second circular contact surface of the valve member comprises an inward facing edge formed by the intersection of the interior surface of the tubular member with the end surface of the valve member that faces the second valve seat; and the electromagnetic actuator comprises an electromagnet having a toroidal, radially-slotted ferromagnetic core of U-shaped cross section fixedly mounted within the valve body coaxially with the valve member, an energizing winding inside the core, and a ferromagnetic annular armature attached to the outside of the valve member for movement axially toward the core in response to energization of the magnet winding by the electric signals.

6. The fuel injection system of claim 5 wherein the biasing means comprises:

a first annular shoulder extending inward from the inner surface of the tubular valve member and facing the second valve seat;

a threaded stud mounted coaxially with respect to the second valve seat and having a head with a second annular shoulder facing the first annular shoulder; and

a compression spring positioned within the tubular valve member and having one end bearing against the first shoulder and an opposite end bearing against the second shoulder to urge the valve member toward the first position, the threaded stud permitting adjustment of the axial spacing between the first and second shoulders and thereby the force exerted by the biasing means tending to urge the valve member toward the first position.

7. In a fuel injection system for internal combustion engines of the type that includes a container of fuel, means for supplying fuel under pressure from the container, a fuel injector associated with each combustion space of the engine, means for producing intermittent electric signals synchronized with engine rotation and of a duration depending on the operative conditions of the engine, and a three-way metering valve having an inlet connected to the means for supplying fuel under pressure, a first outlet connected to the fuel injectors, a second outlet connected to a low pressure return line to the fuel container, and means for actuating the valve intermittently in response to the electric signals to supply variable quantities of fuel to the injectors as a function of the duration of each signal, the improvement wherein the metering valve comprises:

a valve body having an internal chamber;

a first passageway opening into the chamber and communicating with the valve inlet;

a second passageway opening into the chamber and communicating with the first outlet of the valve;

a third passageway opening into the chamber and communicating with the second outlet of the valve; and

a valve member mounted in the chamber for movement by the actuating means in response to the electric signals from a first position in which it prevents communication between the openings of the first and second passageways to a second position in which it prevents communication between the opening to the third passageway and the openings to the first and second passageways, the valve member when intermediate the first and second positions permitting communication between all three openings.

8. The fuel injection system of claim 7 further comprising:

a plurality of recesses in a face of the valve body adjacent the first outlet of the valve, the number of recesses corresponding to the number of injectors in the system;

a cover plate attached in fluidtight relation to the face of the valve body, the cover plate having a portion spaced from the face of the valve body to provide an auxiliary chamber enclosing the first outlet and the plurality of recesses, the cover plate having further:

a plurality of auxiliary passageways, each leading from an opening opposite a corresponding recess to a corresponding fuel line connected with one of the injectors and a plurality of auxiliary seating surfaces, each surface surrounding the opening corresponding to one of the auxiliary passageways;

a plurality of stationary auxiliary electromagnets, one electromagnet being mounted in each recess;

a plurality of magnetic auxiliary armatures, one armature being positioned between each electromagnet and the corresponding seating surface, each auxiliary armature having a contact surface for sealing engagement with the corresponding seating surface when the armature is in a first position; v

biasing means in each recess for urging each auxiliary armature toward the first position for preventing flow between the first outlet of the valve and the corresponding injector; and

a distributor of auxiliary electric signals synchronized with the metering valve electric signals for energizing each auxiliary electromagnet in sequence to actuate the corresponding auxiliary armature to move to a second position against the force of the biasing means, in which position the contact surface is disengaged from the auxiliary seating surface for permitting flow from the means for supplying fuel under pressure to each injector in turn for the duration of the valve energizing signal.

9. The fuel injection system of claim 8 wherein each auxiliary armature comprises:

a fiat ferromagnetic disc having an annular contact surface on one side. 10. The fuel injection system of claim 7 further comprising:

a fuel accumulating recess in a surface of the valve body, the recess communicating permanently with the first assageway; a flexible iaphragm enclosing the fuel accumulating recess;

a cover plate overlying the diaphragm and fastened to the valve body for urging the edges of the diaphragm into sealing engagement with the surface of the valve body surrounding the fuel accumulating recess; and

biasing means positioned between the cover plate and the diaphragm for urging the diaphragm away from the cover plate inward toward the fuel accumulating recess.

Claims

1. In a fuel injection system for internal combustion engines of the type that includes a container of fuel, means for supplying fuel under pressure from the container, a fuel injector associated with each combustion space of the engine, means for producing intermittent electric signals synchronized with engine rotation and of a duration depending on the operative conditions of the engine, and a three-way metering valve having an inlet connected to the means for supplying fuel under pressure, a first outlet connected to the fuel injectors, a second outlet connected to a low pressure return line to the fuel container, and means for actuating the valve intermittently in response to the electric signals to supply variable quantities of fuel to the injectors as a function of the duration of each signal, the improvement wherein the metering valve comprises: a valve body having an internal chamber; a first annular valve seat in the chamber; a second annular valve seat in the chamber, spaced from and facing the first seat; a first passageway opening into the chamber adjacent the outer circumference of the first seat and communicating with the valve inlet; a second passageway opening into the chamber adjacent the inner circumference of the first seat and communicating with the first outlet of the valve; a third passageway opening into the chamber adjacent the outer circumference of the second seat and communicating with the second outlet of the valve; and a valve member mounted in fluid-tight relation to the chamber wall between the openings of the first and third passageways for movement by the actuating means from a first position to a second position in response to the elecTric signals, the valve member having first and second oppositely-facing circular contact surfaces for sealing engagement respectively with the first valve seat when in the first position and with the second valve seat when in the second position, and the valve member further having a passageway joining the inner sides of the first and second circular contact surfaces, whereby the valve member when in the first position permits communication only between the second and third passageway, when in the second position permits communication only between the first and second passageways, and when intermediate the first and second positions permits communication between all three passageways.

2. The fuel injection system of claim 1 wherein the valve actuating means comprises: an electromagnetic actuator connected to the valve member for moving the member from the first to the second position at the commencement of each of the electric signals and a biasing means for returning the valve member to the first position at the termination of each of the electric signals.

3. The fuel injection system of claim 2 wherein the valve chamber comprises a cylinder, the first and second valve seats comprise frusto-conical surfaces at opposite ends of the chamber, and the valve member comprises a tubular piston mounted for fluid-tight sliding engagement with the wall of the cylindrical chamber between the openings of the first and third passageways.

6. The fuel injection system of claim 5 wherein the biasing means comprises: a first annular shoulder extending inward from the inner surface of the tubular valve member and facing the second valve seat; a threaded stud mounted coaxially with respect to the second valve seat and having a head with a second annular shoulder facing the first annular shoulder; and a compression spring positioned within the tubular valve member and having one end bearing against the first shoulder and an opposite end bearing against the second shoulder to urge the valve member toward the first position, the threaded stud permitting adjustment of the axial spacing between the first and second shoulders and thereby the force exerted by the biasing means tending to urge the valve member toward the first position.

7. In a fuel injection system for internal combustion engines of the type that includes a container of fuel, means for supplying fuel under pressure from the container, a fuel injector associated with each combustion space of the engine, means for producing intermittent electric signals synchronized with engine rotation and of a duration depending on the operative conditions of the engine, and a three-way metering valve having an inlet connected to the means for supplying fuel under pressurE, a first outlet connected to the fuel injectors, a second outlet connected to a low pressure return line to the fuel container, and means for actuating the valve intermittently in response to the electric signals to supply variable quantities of fuel to the injectors as a function of the duration of each signal, the improvement wherein the metering valve comprises: a valve body having an internal chamber; a first passageway opening into the chamber and communicating with the valve inlet; a second passageway opening into the chamber and communicating with the first outlet of the valve; a third passageway opening into the chamber and communicating with the second outlet of the valve; and a valve member mounted in the chamber for movement by the actuating means in response to the electric signals from a first position in which it prevents communication between the openings of the first and second passageways to a second position in which it prevents communication between the opening to the third passageway and the openings to the first and second passageways, the valve member when intermediate the first and second positions permitting communication between all three openings.

8. The fuel injection system of claim 7 further comprising: a plurality of recesses in a face of the valve body adjacent the first outlet of the valve, the number of recesses corresponding to the number of injectors in the system; a cover plate attached in fluidtight relation to the face of the valve body, the cover plate having a portion spaced from the face of the valve body to provide an auxiliary chamber enclosing the first outlet and the plurality of recesses, the cover plate having further: a plurality of auxiliary passageways, each leading from an opening opposite a corresponding recess to a corresponding fuel line connected with one of the injectors and a plurality of auxiliary seating surfaces, each surface surrounding the opening corresponding to one of the auxiliary passageways; a plurality of stationary auxiliary electromagnets, one electromagnet being mounted in each recess; a plurality of magnetic auxiliary armatures, one armature being positioned between each electromagnet and the corresponding seating surface, each auxiliary armature having a contact surface for sealing engagement with the corresponding seating surface when the armature is in a first position; biasing means in each recess for urging each auxiliary armature toward the first position for preventing flow between the first outlet of the valve and the corresponding injector; and a distributor of auxiliary electric signals synchronized with the metering valve electric signals for energizing each auxiliary electromagnet in sequence to actuate the corresponding auxiliary armature to move to a second position against the force of the biasing means, in which position the contact surface is disengaged from the auxiliary seating surface for permitting flow from the means for supplying fuel under pressure to each injector in turn for the duration of the valve energizing signal.

9. The fuel injection system of claim 8 wherein each auxiliary armature comprises: a flat ferromagnetic disc having an annular contact surface on one side.

10. The fuel injection system of claim 7 further comprising: a fuel accumulating recess in a surface of the valve body, the recess communicating permanently with the first passageway; a flexible diaphragm enclosing the fuel accumulating recess; a cover plate overlying the diaphragm and fastened to the valve body for urging the edges of the diaphragm into sealing engagement with the surface of the valve body surrounding the fuel accumulating recess; and biasing means positioned between the cover plate and the diaphragm for urging the diaphragm away from the cover plate inward toward the fuel accumulating recess.