GB2067661A

GB2067661A - Fuel supply system for internal combustion engine

Info

Publication number: GB2067661A
Application number: GB8033231A
Authority: GB
Original assignee: Nissan Motor Co Ltd
Current assignee: Nissan Motor Co Ltd
Priority date: 1979-10-15
Filing date: 1980-10-15
Publication date: 1981-07-30
Also published as: FR2467300A1; DE3038804A1

Abstract

A plunger pump 11 pressurising fuel from a feed pump 10 supplies an accumulator 13 connected to electromagnetic fuel injectors 6a to 6d. A potentiometer 23 connected to the accumulator piston 15 provides an accumulator pressure signal which together with other engine operating condition signals is processed to control a valve 12 which regulates the accumulator pressure. The processed signals also regulate the timing and opening duration of the injectors 6. The quantity of fuel injected is dependent upon the accumulator pressure and the injection duration. The fuel supply system may be used with a compression ignition engine or an air intake throttle controlled spark ignition engine, Fig. 5 (not shown). <IMAGE>

Description

SPECIFICATION Fuel supply system for internal combustion engine This invention relates to an improvement in an internal combustion engine provided with a fuel injector valve for supplying with the combustion chambers of the engine with sprayed fuel, and more particularly to a fuel supply system for an internal combustion engine provided with fuel injector valves and a control system for controlling the fuel injection timing and the fuel injection amount in response to engine operation conditions.

In connection with a fuel supply in which fuel in injected directly or indirectly to engine cylinders under a considerably high pressure, such fuel injection is actually employed in the art of diesel engines in which the fuel injector valves are required to be sufficient in pressure-resistance, and additionally a fuel injection pump for pressurizing fuel is necessary. Such a fuel injection pump is in general provided with a function to distribute the fuel into the engine cylinders, and arranged to successively supply high pressure fuel to the fuel injector valves for the respective engine cylinders at predetermined crankangle positions.

However, since the fuel injection pump is mechanically operated in relation with engine rotation, a great effort is required to vary the timing of fuel injection during operation of the engine. Additionally, with such a fuel injection pump, it is technically difficult to automatically obtain desirable fuel injection timing and amount particularly throughout engine operations from a cold engine to a high temperature engine.

Furthermore, in the production of the fuel injection pump, considerable accuracy is required to match the fuel injection amount with the fuel injection timing. As a result, the fuel injection pump becomes expensive and is difficult in maintenance after it is marketed.

In addition to the above, both petrol-powered and diesel engines are recently being subjected to strict exhaust gas emission regulation, and are further required to be higher in fuel consumption efficiency from the standpoint of fuel economy. It will be understood that there is a limit to meet such requirements by using the fuel supply control depending upon the above-mentioned mechanically operated fuel injection pump.

In accordance with the present invention, an internal combustion engine is provided with a fuel supply system which comprises a feed pump for feeding fuel from a fuel source, a pressurizing pump for pressurizing the fuel from the feed pump, accumulating means for accumulating the fuel from said pressurizing pump, a fuel injector valve fluidly connected to the accumulating means, the fuel injector valve being capable of injecting the fuel to supply the cylinder with sprayed fuel when opened, a pressure sensor for sensing the fuel pressure within the accumulating means to generate a signal representing the fuel pressure, a fuel amount regulating valve fluidly connected to said accumulating means, the fuel accumulated in the accumulating means being dischargeable through the fuel amount regulating valve in response to the operation of the fuel amount regulating means, and a control circuit for controlling the operation of the fuel amount regulating valve in response to the signal from the pressure sensor.

With the thus arranged fuel supply system, the pressure within the accumulator is adjusted to a predetermined level by virtue of the fuel amount regulating valve, thereby controlling the fuel injection pressure to a large level. Furthermore, if the operation of the fuel amount regulating valve is modified via the control circuit by a signal from an engine load sensor sensing the position of an accelerator pedal or the amount of intake air, the pressure within the accumulator can be controlled in accordance with engine load, i.e., the fuel injection pressure increases with the increased engine load. As a result, the increase in fuel injection amount can be achieved without prolongation of the fuel injection duration and without rendering the fuel injector valve largesized.

In the accompanying drawings: Fig. 1 is a diagrammatic view, partly in section, of a fuel supply system according to the present invention, in cooperation with a compressionignition internal combustion engine; Fig. 2 is a cross-sectional view of an example of a fuel amount regulating valve used in the system of Fig. 1; Fig. 3 is a cross-sectional view similar to Fig. 2, but showing another example of the fuel amount regulating valve; Fig. 4 is a cross-sectional view of an example of a fuel injector valve used in the system of Fig. 1; Fig. 5 is a diagrammatic view, partly in section, similar to Fig. 1, but showing another embodiment of the fuel supply system according to the present invention, in cooperation with a spark-ignition internal combustion engine; Fig. 6 is a cross-sectional view of another example of the fuel injector valve;; Fig. 7 is a partial cross-sectional view showing a modification of the valve of Fig. 6; Fig. 8 is a partial cross-sectional view similar to Fig. 7, but showing another modification of the valve of Fig. 6; Fig. 9 is a cross-sectional view showing a further modification of the valve of Fig. 6.

Referring now to Fig. 1, an embodiment of a fuel supply system (no numeral) according to the present invention is shown in cooperation with a compression-ignition internal combustion engine (diesel engine). The engine includes an engine block 1 which is formed with a cylinder C or cylinders C, to C4. A piston 2 is reciprocally disposed in each cylinder C and defines a combustion chamber 3 with the crown thereof.

The combustion chamber 3 communicates through an ejection opening 5 with a swirl chamber 4 into which a fuel injector valve (6a) 6 extends to inject fuel into the swirl chamber 4.

Fuel injector valves 6a to 6d are provided respectively for the cylinders C1 to C4. The detailed construction of the fuel injector valve will be discussed later. A glow plug 7 also extends into the swirl chamber 4. An intake air passageway 9 is communicable through an intake valve 8 with the combustion chamber 3 so as to induct air into the combustion chamber 3 therethrough.

The fuel supply system comprises, in addition to the fuel injector valve 6, a fuel feed pump 10 which is operated in timed relation with the engine to feed the fuel from a fuel source such as a fuel tank. The feed pump 10 is connected to a plunger pump 11 through a fuel temperature sensor 46 (will be discussed in detail later) electrically connected to the control circuit 16.

The fuel from the fuel tank is previously pressurized to a certain level, and subsequently the fuel is further pressurized to a high pressure level. The pump 11 is fluidly connected with an accumulator 13 which functions to temporarily store the fuel from the pump 11 to raise the pressure of the fuel therein. The pressure in the accumulator 13 is controlled by an electromagnetically operated fuel amount regulating valve 12. The high pressure fuel from the accumulator 13 is supplied to the fuel injector valves 6a to 6ddisposed at the cylinders CX to C4, respectively.The pressure of the fuel supplied to the fuel injector valve 6 is controlled by the fuel amount regulating valve 12 which is operated in response to a signal from a control circuit 16 which will be discussed later, by which the fuel injection amount depending basically on the opening time period of the fuel injector valve is modified by increasing or decreasing the fuel supply pressure or fuel injection pressure in order to improve the accuracy of the fuel supply control.

The fuel amount regulating valve 12 is disposed in a fuel return line (no numeral) through which the high pressure fuel in the accumulator 13 is bypassed to the sucking side or a fuel passage (no numeral) upstream of the the plunger pump 11, in order to control the return amount of fuel flowing through the return line.

The accumulator 13 comprises a piston 1 5 which is biased by a spring 14, in which the pressure of the fuel stored in a piston chamber 1 5A is controlled by the compressive load of the spring 14, and therefore as the pressure within the piston chamber 1 5A increases, the spring 14 is compressed to raise the pressure of the fuel supplied to the fuel injector valve 6. In other words, assuming that the discharge pressure of the plunger pump 11 is kept constant, as the opening degree of the fuel amount regulating valve 12 increases, the return amount of the fuel through the return line increases with the result that the pressure within the accumulator or the fuel injection pressure is lowered. On the contrary, as the opening degree of the fuel amount regulating valve 12 decreases, the pressure within the accumulator 13 increases.It will be understood that the fuel injection amount from the fuel injector valve 6 relatively increases with the increase in fuel injection pressure, if the fuel injection time period is constant. A potentiometer 23 or pressure sensor is provided to sense the actual pressure in the accumulator 13. The potentiometer 23 is constructed and arranged to vary its output level in response to the displacement of the piston 1 5. The output signal of the potentiometer 23 is supplied to the control circuit 1 6 as a feedback signal. In other words, the opening degree of the fuel amount regulating valve 12 is modified to obtain a target level of the fuel injection amount, upon judgement of the actual fuel injection pressure by virtue of the feedback signal or the output signal from the potentiometer 23.

Fig. 2 shows an example of the fuel amount regulating valve 12 of the ON-OFF type which is generally designated by the character 12'. In this example, the fuel regulating valve 12' comprises an electromagnetic coil 17 which surrounds a movable iron core 18 and is electrically connected to the control circuit 16. A valve member 19 is connected to the iron core 18. Therefore, the valve member 20 opens or closes a valve opening or fuel outlet 20 in the ON-OFF manner in accordance with ON and OFF pulse signals supplied from the control circuit 1 6 to the coil 17.

A fuel inlet (no numeral) is fluidly connected to the accumulator 13. It will be understood from the above, that the fuel amount passing through the return line is proportional to the duty ratio of the pulse signal supplied to the fuel amount regulating valve 12 from the control circuit 16.

Fig. 3 shows another example of the fuel amount regulating valve of the proportional type which is designated by the character 12". In this instance, the fuel amount regulating valve 12" comprises a coil 17' which is connected to a valve member 1 9' and electrically connected to the control circuit 16. The coil 17' is surrounded by a permanent magnet 22. Therefore, when the coil 17 is supplied with a controlled electric current from the control circuit 16, the coil 1 7' moves relative to the permanent magnet 22 in response to the value of the supplied electric current so as to proportionally control the effective opening area of the valve opening or fuel outlet 20'. A fuel inlet (no numeral) is fluidly connected to the accumulator.

Fig. 4 shows the detailed construction of an example of the fuel injector valve 6, which comprises a plug casing 25 which is formed with a threaded section 24 through which the plug casing 25 is screwed in a cylinder head of the engine body 1. Disposed in the plug casing 25 is a nozzle holder 27 in which a nozzle needle 26 is slidably disposed, which nozzle needle 26 is formed at its tip with a tapered section 28. The nozzle holder 27 is formed with a fuel passage 29 to which the fuel from the piston chamber 1 5A of the accumulator 1 3 is supplied. An end of the fuel passage 29 is positioned opposite to, and closable with, the tip tapered section of the nozzle needle 26. Accordingly, the fuel flowing the fuel passage 29 is injected from a nozzle opening 30 in response to the rise of the nozzle needle 26.The nozzle needle 26 is connected through a connecting rod 32 with an armature (movable iron core) 33 which is movable in accordance with the energized or de-energized condition of an electromagnetic coil 34 disposed around the armature 33 which coil is electrically connected to the control circuit 1 6 and forms part of an electromagnetic actuator (no numeral). A coil or return spring 31 is provided to bias the nozzle needle 26 downward or in the direction to close the end of the fuel passage 29.

With the construction of the fuel injector valve 6, when the electromagnetic coil 34 is supplied with signals or ON-OFF type pulse signals from the control circuit 16, the coil 34 is energized to pull up the nozzle needle 26 through the connection rod 32 against the biasing force of the spring 31.

Then, the rise of the nozzle needle 26 is assisted by the fuel pressure acting on the tip tapered section of the nozzle needle 26. Thus, the fuel injector valve 6 is opened to effect a fuel injection.

When the electromagnetic coil 34 is de-energized, the nozzle needle 26 is pushed down under the action of the spring 31 to stop the fuel injection.

It is to be noted that the control circuit 1 6 is supplied with a variety of signals representing the engine operation conditions as shown in Fig. 1, in order to suitably control the fuel injection amount and fuel injection timing in accordance with the engine operating conditions. In this regard, an acceleration sensor 42 is provided to sense the opening degree or angular position of an accelerator pedal 43. The signal from this acceleration sensor 42 functions to increase or decrease the basic fuel injection amount.

Additionally, a crank angle sensor 44 is provided to sense crankshaft rotational angle, top dead center, and engine speed, so as to generate a signal for controlling the fuel injection timing. The reference numeral 45 designates an engine coolant temperature sensor which functions to modify or increase the fuel injection amount during low engine temperature operation. The reference numeral 46 designates a fuel temperature sensor which is arranged to supply a signal to the control circuit 1 6 in order to modify the fuel flow amount in accordance with fuel temperature, i.e., to compensate the fuel flow amount due to temperature rise.Therefore, the control circuit 1 6 generates control signals upon receiving the above-mentioned various signals and supply them respectively to the fuel injector valve 6 and the electromagnetically operated fuel amount regulating valve 1 2, to carry out fuel injection in a desired amount at an optimum timing for each engine cylinder in accordance with the above-mentioned various signals representing engine operation conditions.

The manner of operation of the fuel supply system shown in Fig. 1 will be explained hereinafter with reference to the operations of the above-mentioned component parts.

The fuel injection duration per each fuel injection of the fuel injector valve 6 and the opening degree of the electromagnetically operated fuel amount regulating valve 1 2 are controlled basically in response to the signals from the acceleration sensor 42 through the control circuit 16, so that the fuel injection amount is effectively controlled. The fuel injector 6 is supplied with the pulse signals which are in timed relation to the engine from the control circuit 16, and therefore the fuel injection at each engine cylinder is initiated at an optimum timing in the vicinity of the top dead center on the compression stroke.However, such a required fuel injection timing delicately varies in response to engine operating conditions, it is controlled by minutely adjusting the phase of the pulse signal through the control circuit 16, which phase adjusting is carried out upon judging the engine operation conditions by virtue of a previously set pattern which may have been memorized as a table when using a microcomputer.

The fuel is previously pressurized by the feed pump 10 and then fed to the plunger pump 11 to be further pressurized to a pressure value in the vicinity of a predetermined fuel injection pressure.

This is because the fuel injection pressure is required to be higher than combustion chamber pressure which is considerably high such as 20 to 25 atm due to the higher compression ratio. This high pressure fuel is stored in the accumulator 13, and the stored pressure value or the fuel injection pressure is controlled by the electromagnetically operated fuel amount regulating valve 12.

Simultaneously, this stored pressure value of the accumulator 13 is supplied in feedback manner to the control circuit 1 6 as an output signal of the potentiometer 23, so that it can be judged whether the injection pressure at every fuel injection is in agreement with a target level or not.

Depending upon this judgement, a modification signal from the control circuit 1 6 is supplied to the electromagnetically operated fuel amount regulating valve 12 to modify the fuel flow amount through the fuel amount regulating valve 12.

It will be appreciated that the fuel injection amount from the fuel injector valve depends on the valve opening duration and the fuel injection pressure of the fuel injector valve 6, and therefore the increase in the fuel injection amount is carried out in very high response by raising the injection pressure in addition to increasing the pulse width for fuel injection. It will be understood that the fuel injection amount increase is of course accomplished only by increasing the injection duration even upon allowing the injection pressure to be constant; however, in this situation, it is required to considerably prolong the fuel injection duration or to set the fuel injector valve capacity larger, to increase fuel injection amount. This will lead to the problems in which it becomes impossible to complete the fuel injection within an optimum crankshaft rotational angle range, or the control accuracy at a lesser amount of fuel injection deteriorates due to the large-sized fuel injector valve.

On the contrary, with the fuel supply system according to the present invention, the stored pressure value in the accumulator 13 can be relatively raised in accordance with engine loads, and therefore the increase in the injection amount is accomplished in high response without considerably increasing the fuel injection duration.

Consequently, a predetermined amount of fuel can be positively injected until a required timing under all engine operating conditions, and further the fuel injection amount is accurately controlled by the feedback control of the fuel injection pressure, thereby improving the fuel consumption characteristics, achieving a high response in the increase of the fuel injection amount even at a transitional period of engine operation conditions, and improving acceleration characteristics.

While the principle of the present invention is applicable to diesel engines and the like, it will be understood that it is applicable to compression ignition engines which are operated on fuels whose major component is methanol and added diesel light oil.

As appreciated from the above discussion, according to the present invention, the fuel injection timing and the fuel injection amount can be controlled to a high accuracy and high response, thereby greatly improving the engine operational characteristics and fuel consumption characteristics. Besides, these controls are achieved electronically without depending upon conventional mechanical operation, and accordingly mechanical matching efforts become unnecessary, thereby improving the productivity and maintainability of such a fuel supply system, and lowering the production cost thereof.

Fig. 2 illustrates another embodiment of the fuel supply system (no numeral) according to the present invention, applied to a spark-ignition internal combustion engine including the engine block 1. The engine block 1 is formed with the cylinder C or cylinders C1 to C4. The piston 2 is reciprocally disposed in the cylinder (C) and defines the combustion chamber 3 with the crown thereof. A spark plug 47 is so provided that its electrodes extend into the combustion chamber 3.

Additionally, the fuel injector valve 6 also extends into the combustion chamber 3. The combustion chamber 3 is communicable through the intake valve with an intake passageway 49 or intake manifold through which intake air is inducted into the combustion chamber 3. A throttle valve 48 is pivotally supported within the intake passageway 49, which throttle valve is operatively connected with an accelerator pedal (not shown) so as to be moved thereby.

When a stratified charge of the injected fuel is carried out during the compression stroke including the vicinity of the top dead center in the case where the fuel injector valve 6 is disposed to extend into the combustion chamber 3 as shown, the throttle valve 46 may be omitted to draw a sufficient amount of air into the combustion chamber 3. The fuel injector valve 6 may be disposed in the intake passageway (intake manifold) 49 immediately upstream of the throttle valve 46, in which the fuel is supplied to the combustion chamber 3 after the intake valve 8 has opened. In this case, it is necessary to install the throttle valve 46 to control the amount of air-fuel mixture.The spark plug 4 is so arranged that its spark timing is basically controlled generally the same as in usual spark-ignition engines, i.e. by ignition signals from the control circuit 1 6. The control circuit 1 6 is arranged to be supplied with a variety of signals from the various sensors for sensing engine operating conditions, and always to provide an optimum spark advance value in correspondence with engine operation conditions which are varying with the lapse of time, so that the injected fuel (for example, petrol) from the fuel injector vaive 6 is ignited and burned in the vicinity of the top dead center on the compression stroke.

The reference numeral 50 designates an intake air amount sensor for sensing the amount of intake air flowing through the intake passageway 49, which intake air amount varies in response to the opening degree of the throttle valve 48. The basic fuel injection amount is increased or decreased by the signal from this intake air amount sensor 50. In this case, since the fuel injection takes place at the optimum timing between the middle period and the latter period in the compression stroke, the plunger pump 11 pressurizes the fuel to a predtermined pressure level in the vicinity of the fuel injection pressure which is higher than the pressure within the combustion chamber at that time.

As will be appreciated from the above, with the fuel supply system shown in Fig. 5, a desired amount of fuel can be securely injected until a required timing under all engine operation conditions, and further the fuel injection amount can be accurately controlled by the feedback control for the fuel injection pressure. Besides, fuel amount increase in high response can be achieved even at a transitional period of the engine operating conditions. Further, by carrying out spark ignition to the thus injected fuel with the spark plug 47, stable and effective combustion of the fuel can be obtained even on a very lean airfuel mixture. As a result, fuel consumption and acceleration characteristics of the engine are greatly improved.

It will be understood that, according to the present invention, the injection timing and the injection amount of the fuel injected from the fuel injector valve 6 can be controlled very accurately and in high response, in accordance with the engine operation conditions, thereby greatly improving the engine operating characteristics and fuel economy. Also in this case, since the above-mentioned controls are carried out electronically without depending upon conventional mechanically means, mechanical matching efforts become unnecessary, thereby improving the productivity and maintainability of the fuel supply system, and lowering the production cost thereof.

Fig. 6 shows another example of the fuel injector valve 6 which is of the type using a helical solenoid (referred to as "helenoid" hereinafter).

The fuel injector valve 6 comprises a housing 67 in which a valve holder 60 and a helenoid holder 66 are coaxially disposed. The casing 67 is formed with a fluid inlet 64 fluidly connected to the accumulator 13, while the helenoid holder 1 6 is formed with a fluid outlet 54. Within the helenoid holder 66, a core 57 forming part of the helenoid is securely disposed spaced from the inner surface of the holder 66. A generally cylindrical armature 56 is movably disposed between the core 57 and the inner surface of the helenoid holder 66. The armature 56 is formed with a bottom section 56a which has through holes 70. The bottom section 56a is connected through a connecting rod (no numeral) with a movable valve member 61.The valve member 61 is movably disposed within the valve holder 60 arranged to open or close an opening defined through a valve seat 62 forming part of the valve holder 60, the opening communicating with the fluid inlet 64.

The core 57 is formed at its outer peripheral surface with a helical groove so that the outer surface of the core is formed, in section, into a saw-tooth shape. A helical coil 58 is wound on the surface of the helical groove of the core 57.

Additionally, the armature 56 is formed at its inner peripheral surface with a helical groove whose shape corresponds to that of the helical groove on the core 57. The distance or gap (indicated in Fig. 6) between the corresponding helical grooves in the axial direction of the value is approximately 1 mm maximum, and therefore the stroke of the valve member 61 movable with the armature 56 is approximately 1 mm. This armature 56 has a dimension in which the whole length is 42 mm, and the outer diameter is 22 mm, to generate a driving force of approximately 40 Kg. The armature 56 is slidably supported on the inner surface of the helenoid holder 66 through upper and lower bearings 55 disposed between the helenoid holder 66 and the armature 56.The core 57 is integrally formed with a gap adjusting screw 51 which is securable with a lock nut 52, and therefore location of the core 57 is delicately adjustable to control the above-mentioned gap to an optimum value, by rotating the adjusting screw 51. The reference numeral 53 designates a terminal through which electrical current is supplied to the helical coil 58 from the control circuit 1 6. The core 57 is formed with a central hollow 68 in which a coil spring 59 is disposed to bias the armature 6 downwardly or in the direction that the valve member 61 contacts the valve seat 62. The reference numeral 63 designates an Oring disposed between the valve holder 66 and the housing 67.Accordingly, when the high pressure of the fluid acts on the valve seat 62 to move the valve member 61 upwardly so as to open the valve, the fluid flows through a fluid passage 69 formed between the inner surface of the valve holder 60 and the outer surface of the valve member 61, and then supplied through the through holes 70 into the helenoid. Thereafter, the fluid flows to the fluid outlet 54 through the clearance formed between the core 57 and the armature 56. It will be understood that the valve member 61 may be replaced with a poppet type valve member 61' as shown in Fig. 7, or with a ball type valve member 11" as shown in Fig. 8.

The manner of operation of the fuel injection valve shown in Fig. 6 will be explained hereinafter.

In general, a helenoid is characterized by having an extremely high speed response characteristic and by a large driving force though its lift is smaller than that of conventional solenoids. This is because the effective area of the armature 56 and the magnetic flux density due to the helical coil 58 are increased by virtue of the helical groove, so that the increasing rate in weight of the armature 56 to increase the driving force thereof can be suppressed to a smaller value.

When the electric current is not passed through the helenoid, the armature 56 is biased downwards by the biasing force of the spring 59 so as to bias the valve 61 to contact the valve seat 67. In this case, when a high pressure, for example, of 1 50 Kg/cm2 prevails in the fluid inlet 64, a fluid pressure acting on the valve member 61 is 29.4 Kg, assuming that the effective pressure receiving area is 1 9.6 mm2. Accordingly, the biasing force of the spring 58 is necessary to be set over the above-mentioned fluid pressure in order to allow the valve 11 to contact the valve seat 62 against the fluid pressure so as to maintain an oil and gas-tight seal. To cause the valve member 61 to open against this biasing force, the driving force of the helenoid over the biasing force is required as a matter of course.In other words, if the electric current is now passed through the helical coil 58 so that the upward driving force acts on the armature 56, the valve member 61 is at first opened to flow the fuel from the passage 69 to the through holes 70 by the driving force required for breaking the balance between the fluid pressure pushing up the valve member and the spring (59) force. However, after the valve has been opened, almost no pressure difference exists between the upstream and downstream sides relative to the valve member 61, and therefore the driving force over the biasing force of the spring 59 becomes necessary to cause the valve to remain closed. In this regard, the helenoid in this instant develops the operational force of about 50 Kg as mentioned above, and accordingly it becomes possible to cause the valve to remain open sufficiently.

Together with the opening of the valve, the fluid passes through the clearance between the core 57 and the armature 56, and then flows to the fluid outlet 54, cooling the core and the armature, thereby preventing heat generation of the helenoid and improving the durability thereof. Now, since the stroke of the helenoid is approximately 1 mm, the stroke of this valve member 61 is equal to that of the helenoid. Even such a stroke is sufficiently applicable to practical use in the case where the required flow amount for each valve opening is not so larger. Additionally, since a larger driving force is not required at the initial period of the valve opening, the response characteristic of operation is very high, and therefore the present invention is the most suitable for fuel injector valves which require high speed response.

Fig. 9 shows a further example of the fuel injector valve 6 which is similar to the example of Fig. 6 but so arranged that the driving direction of the helenoid is reversed relative to that of the example of Fig. 6. Accordingly, in this instance, the valve member 61 is forced to contact the valve seat 62 by the driving force of the spring 59 and the armature 56' when the electric current is supplied, and the valve member 66 is opened by virtue of the fluid pressure when the electric current supply is interrupted or decreased.

Therefore, it is sufficiei1t only to arrange the core 57', the helical coil 58' and the like to generate such reversed driving force of armature 56', and therefore the other construction is the same in principle as that of Fig. 6.

As will be appreciated from the above, according to the valve arrangement of Figs. 6 to 9, since the opening and closing actions of the valve member 61 is controlled by the helical solenoid, the control of the high pressure fluid can be accomplished in extremely high response, rendering the valve small-sized and light-weight in construction. Particularly the valve is excellent in high speed initial response, and accordingly it is the most suitable for the case wherein momentary flow control is required. Additionally, it will be appreciated that the fuel injector valve of such a type is widely useable for other fluid controls.

Claims

1. A fuel supply system for an internal combustion engine having a cylinder, comprising: a feed pump for feeding fuel from a fuel source; a pressurizing pump for pressurizing the fuel from said feed pump; accumulating means for accumulating the fuel from said pressurizing pump; a fuel injector valve fluidlv connected to said accumulating means to be supplied with the fuel from said accumulating means, said fuel injector valve being capable of injecting the fuel to supply the cylinder with sprayed fuel when opened; a pressure sensor for sensing the fuel pressure within said accumulating means to generate a signal representing the fuel pressure in said accumulator; a fuel amount regulating valve fluidly connected to said accumulating means, the fuel accumulated in said accumulating means being dischargeable through said fuel amount regulating valve; and a control circuit for controlling the operation of said fuel amount regulating valve in response to the signal from said pressure sensor.

2. A fuel supply system as claimed in Claim 1, in which said accumulating means includes a piston defining a piston chamber to which the pressurized fuel is supplied from said pressurized pump, said piston being biased in the direction to decrease the volume of said piston chamber by a spring, said piston chamber communicating with said fuel injector valve.

3. A fuel supply system as claimed in Claim 2, in which said pressure sensor includes a potentiometer operatively connected to said piston of said accumulating means, said potentiometer generating an electric signal representing the displacement of said piston, and electrically connected to said control circuit.

4. A fuel supply system as claimed in Claim 3, in which said fuel amount regulating valve includes a fuel chamber and having a fuel inlet through which said fuel chamber communicates with said piston chamber and a fuel outlet through which the fuel in said fuel chamber is dischargeable, a movable valve member by which said fuel outlet is closable, a movable armature connected with said valve member, an electromagnetic coil located around said armature and electrically connected to said control circuit.

5. A fuel supply system as claimed in Claim 3, in which said fuel amount regulating valve includes a fuel chamber and having a fuel inlet through which said fuel chamber communicates with said piston chamber and a fuel outlet through which the fuel in said fuel chamber is dischargeable, a movable valve member by which said fuel outlet is closable, an electrically conductive coil connected with said valve member and electrically connected to said control circuit, and a permanent magnet located around said electrically conductive coil.

6. A fuel supply system as claimed in Claim 2, in which said fuel injector valve includes a nozzle holder formed with a fuel passage communicating with said piston chamber of said accumulating means and a fuel outlet through which the fuel from said fuel passage is dischargeable when the communication between said fuel passage and said fuel outlet is established, and a movable valve member slidably disposed in said nozzle holder and capable of blocking the communication between said fuel passage and said fuel outlet, a movable armature connected with said valve member, and an electromagnetic coil located around said armature and electrically connected to said control circuit.

7. A fuel supply system as claimed in Claim 6, in which said valve member is of cylindrical shape and formed at its tip with a tapered section to which the open end of said fuel passage communicates said open end being closable by the tapered section of said valve member.

8. A fuel supply system as claimed in Claim 2, in which said fuel injector valve includes a casing formed with a fuel inlet communicating with said piston chamber of said accumulating means and a fuel outlet through which the fuel within said casing is dischargeable, an electrically conductive generally cylindrical core secured within said casing and formed at its outer peripheral surface with a helical groove, an electrically conductive helical solenoid wound on the helical groove of said core and electrically connected to said control circuit, a generally cylindrical armature movably disposed around said core and spaced from said core, said armature being slidably mounted on the inner surface of said casing and formed at its inner peripheral surface with a helical groove whose shape corresponds to that of said core, a movable valve member connected with said armature, and a valve seat having an opening communicating with said fuel inlet, said opening being closable by said valve member to block communication between said fuel inlet and outlet.

9. A fuel supply ststem as claimed in Claim 8, in which said armature is formed with a bottom section opposed to the bottom section of said core, said bottom section of said armature being formed with through holes through which the fuel from said fuel inlet flows, said valve member being connected to said bottom section of said armature.

10. A fuel supply system as claimed in Claim 9, in which said fuel injector valve includes a spring disposed within a hollow formed on the bottom section of said core to bias the bottom section of said armature in the direction to cause said valve member to contact said valve seat.

11. A fuel supply system as claimed in Claim 10, in which said core, said armature, said valve member, said valve seat, and said spring are coaxially located with each other and with respect to said casing.

12. A fuel supply system as claimed in Claim 11, in which said fuel injector valve includes means for controlling the gap between the corresponding sections of said helical grooves of said core and said armature.

13. A fuel supply system as claimed in Claim 12, in which said gap controlling means includes a gap adjusting screw integrally connected to said core and securable to the casing, said screw being coaxial with said core and projecting out of said casing.

14. A fuel supply system as claimed in Ciaim 13, in which said valve member is formed at its tip with a conical section which is contactable with said valve seat.

1 5. A fuel supply system as claimed in Claim 13, in which said valve member is of the poppet type.

1 6. A fuel supply system as claimed in Claim 13, in which said valve member is of the bali type.

17. A fuel supply system as claimed in Claim 1, further comprising means for sensing engine operating conditions to generate signals representing the engine operating conditions, said engine operating condition sensing means being electrically connected to said control circuit.

18. A fuel supply system as claimed in Claim 17, in which said engine operating condition sensing means includes an acceleration sensor for sensing the position of an accelerator pedal to generate a signal representing the accelerator pedal position, in which said operation of said fuel amount regulating valve is controlled via said control circuit in response to the signal from said acceleration sensor.

19. A fuel supply system as claimed in Claim 17, in which said engine operating condition sensing means includes an intake air amount sensor for sensing the amount of intake air inducted to the cylinder to generate a signal representing the intake air amount, in which the operation of said fuel amount regulating valve is controlled via said control circuit in response to the signal from said intake air amount sensor.

20. A fuel supply system as claimed in Claims 18 or 19, an engine operation condition sensing means includes a crankangle sensor for sensing the rotational angle of a crankshaft to generate a signal representing the crankshaft rotational angle, said crankshaft sensor being electrically connected to said control circuit, an engine coolant temperature sensor for sensing the temperature of an engine coolant to generate a signal representing the engine coolant temperature, said engine coolant temperature sensor being electrically connected to said control circuit, and a fuel temperature sensor for sensing the temperature of the fuel to generate a signal representing the fuel temperature, said fuel temperature sensor being connected to said control circuit.

21. A fuel supply system for a compressionignition internal combustion engine having a cylinder and a swirl chamber communicating with the cylinder, said fuel supply system comprising: a feed pump for feeding fuel from a fuel source; a plunger pump for pressurizing the fuel from said plunger pump; an accumulator for accumulating the fuel from said plunger pump; an electrically operated fuel injector valve fluidly connected to said accumulator to be supplied with the fuel from said accumulator, said fuel injector valve being disposed in the swirl chamber to supply the cylinder with sprayed fuel through the swirl chamber when opened; a pressure sensor for sensing the fuel pressure within said accumulator to generate a signal representing the fuel pressure in said accumulator;; an electrically operated fuel amount regulating valve fluidly connected to said accumulator, the fuel accumulated in said accumulator being dischargeable through said fuel amount regulating valve; and means for sensing an engine operating condition to generate a signal representing the engine operating condition; a control circuit for controlling the operation of said fuel amount regulating valve in response to the signals from said pressure sensor and from said engine operating condition sensing means, said control circuit being capable of controlling the operation of said fuel injector valve in response to the signal from said engine operation condition sensing means.

22. A fuel supply system for a spark-ignition internal combustion engine having a cylinder, a spark plug disposed in the cylinder, said fuel supply system comprising: a feed pump for feeding fuel from a fuel source; a plunger pump for pressurizing the fuel from said plunger pump, an accumulator for accumulating the fuel from said plunger pump; an electrically operated fuel injector valve fluidly connected to said accumulator to be supplied with the fuel from said accumulator, said fuel injector valve being disposed in the cylinder to supply the cylinder with sprayed fuel when opened; a pressure sensor for sensing the fuel pressure within said accumulator to generate a signal representing the fuel pressure in said accumulator;; an electrically operated fuel amount regulating valve fluidly connected to said accumulator, the fuel accumulated in said accumulator being dischargeable through said fuel amount regulating valve; means for sensing an engine operating condition to generate a signal representing the engine operating condition; and a control circuit for controlling the operation of said fuel amount regulating valve in response to the signals from said pressure sensor and from said engine operating condition sensing means, said control circuit being capable of controlling the operation of said fuel injector valve in response to the signal from said engine operation condition sensing means (Fig. 5).

23. A fuel supply system for an internal combustion engine substantially as described with .

reference to, and as illustrated in Fig. 1, or Fig. 5 of the accompanying drawings.