US2918911A - Device for injecting fluid into internal combustion engines - Google Patents

Description

29, 1959 M. R.'GUIOT V 2,918,911

DEVICE FOR INJECTING FLUID INTO INTERNAL COMBUSTION ENGINES Filed Jan. 2, 1958 5 Sheets-Sheet 1 /MZ/g5.

Dec. 29, 1959 M. R. eulof 2,913,911

DEVICE FOR 'INJECTING mm: mo INTERNAL cowsusnon ENGINES Filed Jan. 2, 1958 5 Sheets-Sheet 2 film/eke: E0858;- Gu/or Dec. 29, 1959 v M. R. GUIOT 2,918,911

DEVICE FOR INJECTING FLUID INTO INTERNAL COMBUSTION ENGINES Filed Jan. 2, 1958 5 Sheets-Sheet 3 [271 217 ZQr' M4 UE/CE' EoBERT 60/0 7' Dec. 29, 1959 M. R. GUIOT DEVICE r7012 INJECTING FLUID mro INTERNAL COMBUSTION ENGINES Filed Jan. 2, 1958 5 Shets-Sheet 4 h I E T: 2231-" Moe/c5 ,oaaer 60/07 Dec. 29, 1959 M. R. GUlOT 2,918,911

DEVICE FOR INJECTING FLUID INTO INTERNAL COMBUSTION ENGINES Filed Jan. 2, 1958 5 Sheets-Sheet 5 Fi fi 6 58 65! 19! m av 66 580 v 1 K Z3 J77 V5227 far" Mme/(:5 Easier 60/02- 5 y M LrsQ HZYyQ.

United States Patent DEVICE FOR INJECTING FLUID INTO INTERNAL COMBUSTION ENGINES Maurice Robert Guiot, Paris, France, assignor to Weselco Limited, Toronto, Ontario, Canada, a corporation of Canada Application January 2, 1958, Serial No. 706,835

27 Claims. (Cl. 123-32) This invention relates to devices for injecting fuel or other fluids into internal combustion engines.

Hitherto known injection devices require a high-precision and therefore costly equipment.

, On the other hand, the adjustment of these known injection devices is extremely delicate, due to the lack of flexibility, independence and continuity of the adjustment and control means comprising as a rule parts the dimensions of which are rigidly determined by construction, although their contours are sometimes determined rather empirically.

It is the essential object of the present invention to provide an injection control device adapted to avoid the drawbacks broadly set forth hereabove.

To this end, the device according to this invention for injecting fuel or other fluids into internal combustion engines comprises means for generating oscillations the frequency and amplitude of which are proportional to the velocity of rotation of the engine, means for generating pulses from these oscillations which are subsequently fed to two parallel circuits for controlling the opening and closing of the injectors, said pulses being phase-shifted with one another as a function of various parameters, notably the vacuum obtaining in the induction manifold, the engine speed and the injection pressure, whereby the beginning and the end of the injection are properly timed in relation to the engine cycle of operation for all current values of the various parameters involved.

The hydraulic circuit of the injection device comprises a high-pressure pump,. a pressure-compensating device mounted at the delivery side of this pump, a pressureregulating device adapted to stabilize and adapt the injection pressure to the different engine speeds, and a plurality of pulsating solenoid valves. each adapted to feed a separate injector.

These pulsating solenoid valves comprise each an opening electromagnet and a closing electromagnet, both electromagnets having a common plunger and being alternately energized by opening and closing pulses The oscillation generator consists of a core rotatably driven at a speed proportional to the engine speed and comprising at its outer peripheral portion a number of alternate magnetic poles, and at least one magnetic circuit carrying a coil winding in which generated.

According to a first form of embodiment, one of the magnetic circuits is carried by a disk rotatably movable about the core axis, the other magnetic circuit being stationary; the movable magnetic circuit is adapted to be angularly displaced relative to the stationary magnetic circuit through an angle varying in proportion to the value of the vacuum obtaining in the induction manifold, thus determining the quantity of injected fluid.

According to an alternate form of embodiment the oscillation generator comprises a single fixed magnetic circuit, the oscillations generated in this circuit being subsequently phase-shifted by electric means as a function of the vacuum existing in the induction manifold.

the oscillations are The oscillation generator feeds oscillations to an injection regulator in which these oscillations are phaseshifted by electric means as a function of the difierent parameters cited hereinabove.

These oscillations are also fedfrom the generator to the pressure regulator the correcting action of which is subordinate to the injection requirements.

According to a first form of embodiment of'the oscillation generator the injection regulator comprises two parallel circuits fed from the two outputs of the oscillation generator. The first circuit comprises phase-shifting means adapted to impart a lead to the oscillations, notably as a function of the engine speed and of the injection pressure. The other circuit connected to the stationary magnetic circuit receives moderately phase-shifted oscillations.

The outputs of these two magnetic circuits are fed to the two input terminals of a monostable multvibzator having its two outputs connected to the two parallel circuits for opening and closing the injectors.

In the case of a spark-ignition engine an electronic or electromechanical ignition system is controlled by the phase-shifted oscillations derived from the first circuit of the injection regulator.

According to a specific form of embodiment of this invention, the first injection regulating circuit may comprise a transformer secondary having a grounded center tap; this secondary is connected in series with a first potentiometer, a thermistor and another potentiometer. The function of the thermistor is to produce a phase displacement subordinate to the oscillation frequency, that is, to the engine speed. The position of the slider of the first potentiometer introduces an additional phase dis placement depending on the density and temperature ofthe surrounding atmosphere. Finally, the other potentiometer may comprise two sliders connected the one to the ignition system and the other to one input terminal of the monostable multivibrator.

Thus, in the case of a spark-ignition engine, a welldefined time relationship is obtained between the pulses controlling the beginning of the injection and those controlling the ignition.

The slider of the other potentiometer which is connected to the first input of the multivibrator may be controlled from the injection pressure compensating device, so that the beginning time of the injection may be varied as a function of the pressure and possibly as a function of the temperature of the injected fluid.

In certain cases it is also possible to contemplate the phase shifting of the oscillations fed to the other circuit of the injection regulator as a function of the injection pressure, with the consequence that the end of'the injection is also displaced in the time.

According to another typical embodiment of the oscillation generator the oscillations collected from the single output of this generator are fed to the primary of a transformer having its two secondaries provided with grounded center taps and connected to the two phaseshifting circuits of the injection regulator.

In this case the slider of the first potentiometer of the first circuit is also displaced as a function of the vacuum obtaining in the induction pipe.

The device according to this invention is applicable notably to any internal combustion piston engine wherein the injected fluid is introduced either directly into the combustion chamber or outside this combustion chamber embodied in the practice, reference will now be made to the attached drawings forming part of this specification and illustrating diagrammatically by way of example a few typical embodiments of the present invention. In the drawings:

Figure 1 is a diagram illustrating the basic principle of the injection device according to this invention;

Figure 2 is a wiring diagram illustrating the arrangement of the control and regulating device according to this first embodiment;

Figure 3 is another diagram illustrating the principle of a modified embodiment of a control and regulating device constructed in accordance with the teachings of this invention;

Figure 4 is a wiring diagram of the same embodiment;

Figure 5 is a fragmentary diagram of the hydraulic circuit comprising notably the regulator and the injection pressure compensator;

Figure 6 is a longitudinal axial section illustrating a solenoid valve for feeding fluid to the injectors of the type utilized in the device of this invention, this valve being in its open position;

Figure 7 is a longitudinal axial section illustrating the same valve in its closed position; and

Figure 8 is a wiring diagram illustrating a known transistor oscillator included in the ignition system.

In Figure I the oscillation generator comprises a core 1 of circular, spider or other adequate form, having in this example eight alternate north-south poles disposed at spaced intervals at its outer periphery. This core 1 is rotatably driven in the clockwise direction at a velocity proportional to the engine speed. In the example described hereafter the injection device according to this invention is assumed to equip a four-cylindered, fourstroke engine. Consequently, the velocity of rotation of the core 1 is half the engine speed. The nerth-south poles move past pole pieces of two magnetic circuits 2, 3 which in their inoperative positions are spaced 180 apart. The magnetic circuit 2 is stationary and carries a coil winding 4 having one end grounded and the other end connected to one input terminal of an injection regulator 5 shown in block form.

The magnetic circuit 3 carries similarly a winding coil 6 having one end grounded and the other end connected to another input terminal of the regulator 5. The magnetic circuit 3 and winding 6 are mounted on a plate '7 angularly movable about the axis of core 1. The angular displacement of this plate 7 is a function of the vacuum obtaining in the induction manifold 8 of the engine. This vacuum controls for example through a diaphragm 9 and a rocker arm 11 the angular movement of plate 7. Thus, the magnetic circuit 3 and winding 6 may be shifted angularly, relative to the magnetic circuit 2 and winding 4, through an angle a which is a function of the vacuum obtaining in the induction manifold 8.

A corrector I2 is also connected to one input terminal of regulator 5. This corrector is designed to modify the operation of the regulator 5 as a function of various parameters such as the air density and temperature.

Connected to the regulator 5- are three output conductors, that is, a conductor 13 adapted, in the case of a spark-ignition engine, to feed an ignition system, and conductors 14a, 14f controlling in parallel the beginning and the end of the injection.

These conductors 14d and 14 are connected to the contact arms 15d, 15] respectively of injection distributors 16d, 16,. These contact arms 15d, 15 are rotatably driven at the same velocity as core 1 and adapted to contact conducting segments 17d, 17f respectively which are separated by insulating segments 18d, 18;". Each conducting segment 17d, 17 is connected through a conductor 19d, 19] to the pair of input terminals of a pulsating solenoid valve 21 controlling the supply of fuel or like fluid to the corresponding engine cylinder 22.

The injection circuit proper comprises a fuel tank 23,.

a high-pressure pump 24 delivering fuel to the different injectors 25 through an injection-pressure compensator 26. On the other hand, the pressure regulating device 27 controlling the injection pressure is connected through a conductor 28 to the coil winding 6. The output of pressure compensator 26 is connected in parallel through a pipe line 64 to the different pulsating solenoid valves 21 corresponding to the various engine cylinders 22.

The pressure compensator 26 controls through a connection 29 the injection device 5.

in the case of a spark-ignition engine the conductor 13 is connected to an electronic or electromechanical ignition system comprising for example an oscillator 31 the output of which delivers current pulses to the primary 32 of a step-up transformer. The secondary 33 of this transformer is connected to the contact arm of a distributor 34 through which sparks are delivered sequentially to spark plugs 35.

Now reference will be made of Fig. 2 illustrating the wiring diagram of the injection regulator and injection pressure regulators 5, 27.

In this diagram the coil winding 4 carried by the magnetic circuit 2 is connected to the primary 37 of a transformer having its secondary 38 connected in series with a capacitor 39 and a potentiometer 41, the center tap of this secondary being grounded.

Likewise the coil winding 6 is connected to the primary 42 of another transformer having its secondary 43 mounted in series with a potentionmeter 4-4, a thermistor 45 and another potentiometer 46, the center tap of this transformer being also grounded;

The slider 41a of potentiometer 41 is connected to one input terminal ofmonostable multivibrator 47.

This monostable multivibrator 47 comprises two transistors 48 and 49. The slider 46a of potentiometer 46 is connected to the other input of the monostable multivibrator 47.

The aforesaid conductors 14d and 149 are connected to the pair of output terminals of the monostable multivibrator 47 respectively, that is, to the pair of collector electrodes of transistors 48 and 49.

The potentiometer 46 is also provided with another slider 46b connected to conductor 13. The position of the slider 44a of potentiometer 44 is controlled by the corrector 12.

The pressure regulator 27 connected through a conductor 28 to the coil winding 6 comprises a parallel assembly comprising a resistor 51 and a thermistor 52, this assembly being in series with the winding 53 of an electromagnet 54 the purpose of which will be described more in detail presently.

The operation of the injection device illustrated diagrammatically in Figs. 1 and 2 is as follows:

When the internal combustion engine is running, the core 1 rotatably driven therefrom generates oscillations in the coil windings 4, 6 at a frequency and an amplitude increasing linearly with the rotational speed of the engine.

ing 4 through an angle 11 depending on the vacuum obtaining in the induction manifold 8. In fact, this vacuum is used to control the angular displacement of the plate 7 about the axis of rotation, of the core 1, as already explained.

The oscillations flowing through the winding 6 are fed to the first input terminal of regulator 5, that is, to the primary 42, and also to the Winding 53 of pressure regulator 27.

The oscillations collected in the secondary 43 are fed.

to the potentiometers 44, 46 and also to the thermistor 45. As the oscillation amplitude increases linearly with the engine speed, this thermistor 45 will introduce a phase displacement in these oscillations which is a. function of the engine speed. Thus, oscillationshaving. an,

The oscillations produced in the winding 6 are: phase-shifted in relation to those produced in the windadvance increasing with the engine speed are obtained across the terminals of potentiometer 46.

The slider 46b receives oscillations fed through the conductor 13 to control the operation of the oscillator 31 with an advance subordinate to the engine speed.

The slider 46a is also fed with similarly phase-shifted oscillations applied to the first input terminal of the monotable multivibrator 47 which is connected to the base of transistor 48.

The corrector 12 acting on the slider 44a of potentiometer 44 acts as a means for correcting the phase-shifting of these oscillations as a function of the air temperature and density.

The oscillations fed to the other input terminal of input terminals connected to the emitter electrodes of transistors 48, 49.

The position of slider 46b which determines the ignition lead may be adjusted either manually, or automatically as a function of any other parameters.

Besides, the position of sliders 41a and 46a may be adjusted at will either manually or automatically. Figure 2 illustrates a diagrammatic connection 29 through which the injection pressure compensator 26 controls the slider 46a to vary the phase-displacement of the oscillations fed to the first input tenninal of the monostable multivibrator 47 as a function of pressure variations. If desired, an auxiliary connection 29a acting on the slider 41a may also be provided, for example in the case of a diesel engine in which the injection end time may vary as a function of the injection pressure.

Thus, to sum up, the first input terminal of the monostable multivibrator 47 is fed with oscillations having an advance subordinate to the following parameters: Vacuum in the induction manifold (through plate '7), engine speed (thermistor 45) air density and temperature (potentiometer 44), injection pressure (slider 46a). The other input terminal of the monostable multivibrator 47 is fed with oscillations having a moderate phase-shift (through slider 41a).

The monostable multivibrator 47 supplies the conductors 14d, 14 for the beginning and end times of the injection respectively with rectangular pulses of opposite polarities. Only the negative alternations of the oscillations fed to the two inputs are effective to operate the monostable multivibrator 47. When a leading negative alternation is fed to the base electrode of transistor 48, it releases the latter while blocking the transistor 49, so that the conductor 14d controlling the beginning of the injection is brought to a +V (volts) potential. At the same time the conductor 14 controlling the end of the injection is substantially at 0 volt potential. When a negative alternation is fed to the base electrode of transistor 49 with a certain time lag relative to the preceding one, this transistor is released and the other transistor 48 is blocked automatically. Consequently, the potential of conductor 14) controlling the end of the injection will raise in turn to the aforesaid +'volts value, whereas the potential of conductor 14d controlling the beginning of the injection drops again to 0 volt.

The rectangular pulses collected in conductors 14d and 141 are fed through the injection distributors 16d, 16] respectively to the two opening and closing input terminals of the pulsating solenoid valves 21. The injection time obtaining in each cylinder is therefore a function of the duration of the pulse flowing through the conductor 14d controlling the beginning of the injection; in other words, this injection time is a function emitter and base electrodes.

6. of the time-lag between two negative alternations occurring at the input terminals of the monostable multivibrator 47.

Besides, as the oscillations delivered from the sliders 46a and 46b are phase-shifted with one another through an angle depending on their positions, the ignition timing is also shifted with precision relative to the beginning of the injection.

Figure 8 illustrates a wiring diagram of a known transistor oscillator adapted to be incorporated in the ignition system.

In this figure, the oscillator comprises a transistor 80 of the PNP junction type. This transistor is normally blocked by properly selecting the bias voltage of its The positive release pulses fed to conductor 13 are transmitted through a diode 81 and a resistor 82 to the emitter electrode of transistor 80. By adequately selecting the value of resistor 82, it is possible to determine once for ever the level at which the oscillator will become operative. Thus, the transistor oscillator emits trains of oscillations which are fed to the primary 32 of the step-up transformer.

Now the function and operation of the regulator 27 and compensator 26 of the injection pressure will be described more in details with reference more particularly to Fig. 5.

In this figure the injection pressure compensator 26 consists of a vessel partly filled with fuel. The space 26a overlying the fluid level is filled with an inert gas under pressure, for example nitrogen. At the upper portion of this vessel a pressure-responsive device 26b is provided which acts through a connection 29 to control the regulator 5 as a function of the fuel injection pressure. A thermal rod 260 immersed in the fuel contained in the vessel 26 is connected to the pressure-responsive device 26b so as to control jointly therewith the connection 29 according to fuel temperature variations.

This compensator 26 is effective to maintain the'fuel injection pressure in case of sudden output variations. In fact, this injection pressure is controlled from the pressure regulator 27 and is closely dependent on the amplitude of the oscillations generated in the winding 6, that is, on the engine speed.

This pressure regulator 27 consists of an electromagnet 54 having a plunger 54a disposed within 'a case 60. A valve member 61 is unseated by the pressure of the fuel delivered from the pump 24 through the pipe line 64 from the solenoid valve 21. The fuel pressure action is partly compensated by a return spring 62 urging the valve member 61 to its seated position to close the pipe line 59, the correction being effected by the attraction of the plunger 54a when the winding 53 is energized.

In the position illustrated in Fig. 5 one portion of the fluid delivered by the pump 24 is returned directly to the fuel tank 23 through the return line 63. Consequently, the pressure in the pipe line 64 depends on this quantity of fuel, on the force of the return spring 62 and on the value of the energization of winding 53. Now this winding 53 (see Fig. 2) is connected to the winding 6 through the assembly comprising the resistor 51 and thermistor 52 in parallel. Due to the resistance curve as a function of the thermistor voltage, the energizing voltage applied to the winding 53 may be governed by any suitable law according to fuel injection requirements.

In Figsf6 and 7 of the drawings the pulsating solenoid valve 21 illustrated consists essentially of a pair of electromagnets 65d, 65 having a common plunger 66. These electromagnets may be of the type known under the trade name of Selenoid. The windings 67d and 67 of these electromagnets are connected to conductors 19d and 19f respectively. The same electromagnets 65d and 65 are disposed inside a common body 68 comprising an inlet 68a .for the fluid under pressure which is connected to the pipe line 64, an outlet 68b for the fluid under pressure which leads to the injector 25, and another outlet 68:;

constituting the return line to the tank 23. The axially 4 movable. plunger 66 is solid with a slide-valve distributor 69 in which a duct 69a is formed, as shown. A passage 68a connects the chamber in which the slide valve 69 is slidably mounted to the chamber in which the electromagnets are mounted.

When the conductor 19d is brought to a potential. +V (volts), the winding 67d controlling the beginning of the injection phase is energized and attracts the core 66 downwards, that is, to the position shown in Fig. 6 which is the open position of the solenoid valve 23.. in this position the duct 69a connects the high-pressure line 64 with the relevant injector 25.

When at the end of the injection process, the conductor 19f is brought in turn to the potent al +V (volts) asconductcr 19d resumes the ground potential. the winding 67a. is de-energized whereas the wind ng 67f becomes energized. The plunger 66 is attracted upwards as well as the slide valve 69 solid therewith which takes the position in which it is shown in Fig. 7.

The above-described solenoid valve is characterized by many advantageous features. Firstly, when the electromagnct 67d controlling the beginning of the injection process is energized. the descending slide valve 9 acts as a piston and injects the fuel contained in the lower chamher 682 formed between the lower end of the pistonforrning slide valve and the bottom of the body 68, thus developing preliminary shock wave in the duct leading 25. This shock wave will on the one hand le case of a needle-type injector, and on the other hand force the injection pressure during the initial phase of the injection period. Then, when the slide valve 59 has attained its lowermost position (Fig. 6) the constant injection pressure is established and maintained throughout the injection period.

When the solenoid valve El is closed, the ascending movement of the slide valve on exertsa suction on the fuel contained the duct leading to the injector 25, thereby preventing the latter from leaking into the relevant engine cylinder.

The chamber 68c can be filled through the duct 68a communicating with the aforesaid chamber 636 through the duct we. In this case a spring 58 moves the assembly 6669 through a distance sufficient to close the communication 68a''69a so that in case the electromagnet 65) were not energized the duct 68d will be closed to prevent the occurrence of any leak.

In the mod fied embodiment of the injection device according to this invention which is illustrated in Figs. 3 and 4 of the drawings the oscillation generator comprises only one magnetic circuit 2 carrying the winding 4. The oscillations generated in this Winding 4 are fed to the injection regulator 5 and also to the conductor 28 leading to the injection pressure regulator.

These oscillations are applied to the primary winding 7% of a transformer comprising two secondary windings 7t, 7?, having grounded center taps. The potentiometers 44, 46 and thermistor 45 are connected in series to the secondary 71, and the potentiometer 41 is connected to the other secondary 72.

In this specific embodiment the vacuum created in the induction manifold 3 controls the corrector 12 acting in turn on the slider 44a of potentiometer 44. This corrector 12 is also responsive as in the first case to the parameter such as air density and temperature.

In this modified embodiment the phase displacement produced by the vacuum in the induction manifold is used to control electric means instead of the mechanical means of the first form of embodiment. The other component elements of regulator 5 are similar to those already described and are therefore designated by the same reference numerals.

Although the above description and attached drawings refer mainly to the application of the injection device of this invention to '2. spark-ignition, four-stroke, four-cylindered engine, it will be readily understood by anybody conversant with the art that this device is also applicable to any system requiring a periodic fluid-metering opera-- tion, and that many modifications may be brought to these exemplary embodiments without departing from the spirit and scope of this invention as set forth in the appended. claims.

What I claim is:

1. A device for injecting a fluid into internal combustion engines which comprises at least one injector, means for supplying said injectors with a fluid under pressure, a first electric opening circuit acting on said means to. feed said injectors when said first opening circuit is actuated, another electric closing circuit acting on said means to discontinue the supply of fluid to said injectors when said other circuit is actuated, means for generating oscillations the frequency and amplitude of Which are proportional to the velocity of rotation of the engine, means for phase-shifting said oscillations With one another as a function of the vacuum in the induction manifold, the engine speed, the injection pressure and the air density and temperature, and other means for generating from said phase-shifted oscillations control pulses fed to said first and second electric circuits, whereby the beginning and the end of the injection period take place at proper moments of the cycle of rotation of the engine.

2. Injection device for internal combustion engines, comprising at least one injector, a fluid tank, a high-pressure pump fed from said tank, pressure-compensating means for maintaining the injection pressure to a constant value during sudden variations in the fluid output, a plurality of pulsating solenoid valves having a firstcon trol inlet and a second control inlet, said solenoid valves being connected in parallel to said pump and controlling each a separate injector, a first electric opening circuit connected to the first inlet of said solenoid valves, another electric closing circuit connected to the other inlet of said solenoid valves, means for generating oscillations the frequency and amplitude of which are proportional to the velocity of rotation of the engine, means for adjusting the injection pressure as a function of the engine speed by means of said oscillations, means for phasedisplacing said oscillations as a function of the vacuum obtaining in the induction manifold, the engine speed, the injection pressure and the air density and temperature, and other means for generating from said oscillations control pulses acting on said first and second electric circuits, said pulses controlling the opening andv closing of said pulsating solenoid valves respectively.

3. An injection device as set forth in claim 2, comprising a return circuit leading from the delivery side of said high-pressure pump to said tank, means for variably obturating said return circuit, an electromagnet controlling said obturating means to vary the fluid pressure at the delivery side of said pump, an electric network connected across said oscillation generator and said electromagnct so as to feed thereto an energizing voltage consistent with the oscillation frequency, said voltage varying as a function of the engine speed according to a predetermined law consistent with the injection requirements, said law being determined after the transfer characteristic of the electric network.

4. An injection device as set forth in claim 3, wherein said electric network consists of a resistance and a thermistor connected in parallel.

5. A device as set forth in claim 2, wherein each pulsating solenoid valve comprises a body formed with a high-pressure fluid inlet connected to said pump, a fluid outlet connected to said injector and a return outlet leading to said tank, an opening electromagnet and a closing electromagnet mounted in said body, said electromagnets being connected to the two control input terminals of said solenoid valve respectively, and axially movable plunger common to both electromagnets, a cylindrical cav ity in said body which is limited by a side wall and a bottom, a'slide-valve solid with said plunger and axially mov able in said cavity, said high-pressure fluid inlet opening into said side wall of said cavity and said injector-feeding fluid outlet being connected withthe bottom of said cavity, said slide valve being adapted to connect said high-pressure fluid inlet with said fluid outlet connected to said injector when said opening electromagnet alone is energized, and discontinuing said connection when said closing electromagnet alone is energized, said slide valve also acting as a piston to on the one hand force any fluidpresent from the chamber formed between said slide valve and said bottom of said cavity towards said injector when said opening electromagnet is energized and attracts said plunger, and on the other hand exhaust any fluid remaining in the outlet connected to said injector when said closing electromagnet is energized in turn, to prevent said injector from leaking into the engine cylinder associated therewith.

6. Injection device as set forth in claim 5, wherein said slide valve in its closed position causes the chamber formed between said slide valve and .said bottom of said cavity to communicate with said outlet leading to said tank in order constantly to keep said chamber filled with fluid.

7. Injection device as set forth in claim 6, wherein return means are provided so that when none of said opening and closing electromagnets is energized said slide valve will discontinue any communication between said highpressure fluid inlet and the outlet connected to said injector, on the one hand, and between said return outlet leading to said reservoir and the outlet connected to said injector, on the other hand.

8. Injection device as set forth in claim 2, wherein said means for generating oscillations comprise a core rotatably driven at a velocity proportional to the engine speed, a plurality of alternate magnetic poles disposed at spaced intervals around the outer periphery of said core, at least one magnetic circuit having pole pieces so disposed that said magnetic poles move past said pole pieces during the operation of the device, and a winding carried by each of said magnetic circuits, in which said oscillations are generated.

9. Injection device as set forth in claim 8, comprising a stationary magnetic circuit, a movable magnetic circuit driven for rotation about the aXis of said core, and means for angularly shifting said movable magnetic circuit relative to said stationary magnetic circuit through an angle varying as a function of the vacuum obtaining in the induction manifold of the engine.

10. Injection device as set forth in claim 9, wherein said means for phase-shifting said oscillations and generating control pulses comprise a first phase-shifting circuit connected to the winding carried by said movable magnetic circuit, said first phase-shifting circuit occasionating phase-displacement of the oscillations generated in said winding as a function notably of the engine speed and of the injection pressure, another phase-shifting circuit connected to the winding carried by said stationary magnetic circuit and adapted to create a phase-displacement in the oscillations generated in said winding, a monostable multivibrator having two input terminals and two output terminals, said two input terminals being connected to the first and second phase-shifting circuits respectively and the corresponding output terminals being connected to said opening and closing circuits of said injectors respectively.

11. Injection device as set forth in claim 10, wherein said pressure compensating means comprise a cavity connected to the delivery side of said high-pressure pump, an inert gas under pressure filling said cavity in contact with the free surface of the fluid, means responsive to the fluid pressure for controlling the phase-displacement of said first and second phase-shifting circuits as a function of said pressure, and means responsive to the fluid temperature for controlling the phase-shifting of said first as a function of said said first phase-shifting circuit comprises an input transformer having a primary winding and a secondary winding, said primary Winding being connected to the winding carried by said movable magnetic circuit, said secondary winding having a grounded center tap, a first potentiometer, a thermistor, and another potentiometer connected in series with said secondary winding, said thermistance creating a phase-shift proportional to the engine speed.

14. Injection device as set forth in claim 13, wherein said first potentiometer comprises a slider adapted to short-circuit one portion of its resistor, and wherein means are provided for varying the position of said slider as a function of the density and temperature of the surrounding atmosphere, and consequently creating an additional phase-displacement of said oscillations.

15. Injection device as set forth in claim 13, wherein said other potentiometer of said first phase-shifting circuit comprises a first slider connected to the first input I terminal of said monostable multivibrator and wherein means responsive to the pressure and temperature of said fluid are provided for varying the position of said first slider in order to modify the phase-displacement of the oscillations fed to said first input terminal of said monostable multivibrator as a function of the injection pressure and fluid temperature.

16. Injection device for spark ignition engines as set forth in claim 15, comprising an'ignition system adapted to be controlled by oscillations and wherein said other potentiometer of said first phase-shifting circuit is provided with another slider connected to the oscillationcontrolled ignition system, whereby the ignition controlling oscillations collected by said other slider are phaseshifted in relation to those collected by said first slider.

17. Injection device as set forth in claim 11, wherein said other phase-shifting circuit comprises an input transformer having a primary winding and a secondary winding, said primary winding being connected to the winding carried by said stationary magnetic circuit, said secondary winding having a grounded center tap, a potentiometer in series with said secondary winding, said potentiometer having a slider connected to the other input terminal of said monostable multivibrator.

18. Injection device as set forth in claim 17, wherein means are provided for varying the position of the slider of the potentiometer of said other phase-shifting circuit, said means being controlled by means responsive to the fluid pressure and temperature.

19. Injection device as set forth in claim 8, wherein said oscillation generating means comprise a single stationary magnetic circuit and a winding carried by said stationary magnetic circuit.

20. Injection device as set forth in claim 19, wherein said means for phase-shifting said oscillations and generating control pulses comprise an input transformer having a primary winding and two secondary windings, said primary winding being connected to the winding carried by said stationary magnetic circuit, said two secondary windings having grounded center taps, a first phase-shifting circuit comprising said first secondary winding and creating a phase-displacement of the oscillations gen-- ill nals being connected to said first and second phase-shifting circuits respectively whereas said two output terminals are connected to the injector closing and opening circuits respectively.

21. Injection device as set forth in claim 20, wherein said pressure compensating means comprise a cavity connected to the delivery side of said high-pressure pump, an inert gas under pressure filling said cavity and contacting the free fluid surface, means responsive to the fluid pressure to control the phase-shifting action of said first and second phase-shifting circuits as a function of said pressure, and means responsive to the temperature of said fluid to control the phase-displacement of said first and second phase-shifting circuits as a function of said temperature.

22. Injection device for spark-ignition engines as set forth in claim 20, comprising an ignition system adapted to be operated by means of oscillations, and means for applying to said ignition system the oscillations delivered from said first phase-shifting circuit.

23. Injection device as set forth in claim 20, wherein said first phase-shifting circuit comprises a first potentiometer, a thermistor, and another potentiometer connected in series with the first secondary winding, said thermistance bringing about a phase-displacement of said oscillations as a function of the engine speed, and wherein said other phase-shifting circuit comprises a potentiometer connected to the other secondary winding.

24. Injection device as set forth in claim 23, wherein said first potentiometer of said first phase-shifting circuit comprises a slider adapted to short-circuit part of its resistance and wherein means are provided for varying the position of said slider as a function of the vacuum obtaining in the induction manifold and of the air temperature and density, in order to bring about a corresponding phase-displacement of the oscillations.

25. Injection device as set forth in claim 21, wherein said other potentiometer of the first phase-shifting circuit comprises a first slider connected to the first input terminal of said monostable multivibrator and wherein means are provided for varying the position of said slider. which are controlled by means responsive to the fluidpressure and temperature so as to vary the phase displacement of the oscillations applied to the first input terminal of said monostable multivibratoras a function of the fluid pressure and temperature.

26. Injection device for spark-ignition engine asset forth in claim 25, wherein said other potentiometer of the first phase-shifting circuit has another slider connected to the oscillation-controlled ignition system whereby the oscillations controlling said ignition system which are collected by said other slider are phase-shifted in relation to those collected by said first slider.

27. Injection device as set forth in claim 23, wherein means are provided for varying the position of the potentiometer slider of the other phase-shifting circuit under the control of means responsive to the fluid pressure and temperature.

No references cited.

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