US3690306A - Fluidic control system of fuel injection device for internal combustion engines - Google Patents

Abstract

A control system for a fuel injection device of internal combustion engine, which comprises trigger pulse generator for generating a trigger pulse in synchronism with the rotation of an internal combustion engine, a variable circuit-length device by which the length of a fluid passage can be varied according to the load on the engine and a fluidic control circuit for generating a fluidic pulse of a variable width in cooperation with said variable circuit-length device, and in which the trigger pulse generated by said trigger pulse generator is applied to the fluidic control circuit and said variable circuitlength device, whereby a fluidic pulse is generated by said fluidic control circuit and the fluidic pulse thus generated is used for controlling the quantity of fuel supplied to the engine.

Description

[54] FLUIDIC CONTROL SYSTEM OF FUEL INJECTION DEVICE FOR INTERNAL COMBUSTION ENGINES Inventors: Kazuma Matsui, Toyohashi; Hideo Tsubouchi, Kariya, both of Japan Assignee: Nippondenso Kabushiki Kaisha,

Kariya-shi, Aichi-ken, Japan Filed: March 30, 1971 Appl. 190.; 129,544

[30] Foreign Application Priority Data US. Cl.....123/119 R, 123/103 R, 123/139 AW,

123/DIG. 10, 261/DIG. 69

Int. Cl. ..F02n 37/14, Fl5c l/00, F02d 11/08 Field of Search ..123/119 R, 103 R, 139 AW,

DIG. l0; 261/DIG. 69

. generator for [451 Sept. 12, 1972 [56] References Cited UNITED STATES PATENTS 3,556,063 l/l97l Tuzson ..l23/103 R 3,585,975 6/1971 Tonegawa et al...l23/DIG. 10 3,616,782 ll/l97l Matsui et al. ..123/1l9 R Primary Examiner-Wendell E Bums AttorneyCushman, Darby & Cushman [57] ABSTRACT A control system for a fuel injection device of internal combustion engine, which comprises trigger pulse generating a trigger pulse in synchronism with the rotation of an internal combustion engine, a variable circuit-length device by which the length of a fluid passage can be varied according to the load on the engine and a fluidic control circuit for generating a fluidic pulse of a variable width in cooperation with said variable circuit-length device, and in which the trigger pulse generated by said trigger pulse generator is applied to the fluidic control circuit and said variable circuit-length device, whereby a fluidic pulse is generated by said fluidic control circuit and the fluidic pulse thus generated is used for controlling the quantity of fuel supplied to the engine.

7 Claims, 25 Drawing Figures PATENTED l 2 I972 3.690. 306 sum 01' or 11 PATENTEDsmzmz 3.690.306

SHEET 02 0F 11 'fu(mm sec) F I 4 t 760 (mm Hg) 660 (mm Hg Max" Min PATENTED 12 I972 3.690.306

SHEET USUF 11 F l G. 6

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Tb (mm sec) I Max Min"

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t 0 760 (mm Hg) 660 (mm Hg) Min FLUIDIC CONTROL SYSTEM OF FUEL INJECTION DEVICE FOR INTERNAL COMBUSTION ENGINES This invention relates to a control system for a fuel injection device of internal combustion engines which injects fuel directly into the suction manifold of the engine while atomizing the fuel without using a carburetor.

As a fuel injection device of internal combustion engines, there has been used a suction type carburetor which utilizes the vacuum pressure at the Venturi portion in the suction pipe of an engine,a mechanical injection device which injects fuel directly into each cylinder or suction manifold of an engine without using a carbureter of the type described, or an electrical injection device which has electronic means at a fuel controlling portion thereof.

The suction type carbureter mentioned above sucks and discharges fuel by making use of a pressure lowering of the suction gas at a fixed Venturi or variable Venturi. The fixed Venturi type carbureter, as is well known, has the disadvantage that systems for a low speed operation, an intermediate speed operation and a high speed operation must inevitably be separated from each other according to the velocity range of the suction gas flow and a smooth operation of the engine is impaired at the point when the carburetor is connected to each system. On the other hand, the variable Venturi type carburetor can eliminate the above-described disadvantage of the fixed Venturi type, but has the disadvantage that mechanisms for operatively associating a variable fluidic resistance provided in the fuel passage with the variable Venturi, and said variable Venturi with the flow rate of air sucked into the engine, etc., not only call for a precision in machining but also become complicated in construction and large in size, and thus theproduction cost thereof becomes high.

The mechanical and electronic injection devices are also complicated in construction and high in production cost, and therefore, are rarely used for internal combustion engines other than those which are used for special applications.

The first object of the present invention is to provide a control system which controls a fuel injection device of internal combustion engines in such a manner that an adequate quantity of fuel as demanded by the engine can be supplied to the engine continuously from a low speed operation to a high speed operation of the enme. g The second object of the invention is to provide a control system which is simple in construction, easy to manufacture and capable of operating the fuel injection device of the internal combustion engine with high accuracy.

The third object of the invention is to provide a control system which controls the fuel injection device in such a manner that, in a high speed, high load region of the engine, fuel is injected continuously except for a very short period of time corresponding to the pulse interval, and as a result, enables the capacity of a pump to be reduced which delivers the fuel to fuel injecting portions with pressure.

The fourth object of the invention is to provide a control system which controls the fuel injection device in such a manner that an optimum quantity of fuel which has been compensated according to an atmospheric pressure change, is supplied to the engine.

The fifth object of the invention is to provide a control system for the fuel injection device, which comprises a multi-element as a fluidic control circuit and an electrically operated compressor as a source of compressed air for said element, and the function of which will not be impaired even if compressed air is supplied during stoppage of the engine.

According to the present invention, there is provided a control system for a fuel injection device of internal combustion engines, which comprises trigger pulse generating means for generating a trigger pulse in synchronism with the rotation of an internal combustion engine, variable circuit-length means by which the length of a fluid passage can be varied according to the load on said engine and fluidic control circuit for generating a fluidic pulse of a variable width and a variable number in cooperation with said variable circuitlength means and said trigger pulse generating means, the trigger pulse generated by said trigger pulse generating means being applied to said fluidic control circuit and said variable circuit-length means, whereby a fluidic pulse is generated by said fluidic control circuit, which is used for controlling the quantity of fuel supplied to said engine.

FIG. 1 is a diagram showing, partially in section and partially schematically, a first embodiment of the control system according to the invention as applied to an internal combustion engine;

FIG. 2 is a longitudinal cross-sectional view showing in an enlarged scale the variable circuit-length (fluid flow) device shown in FIG. 1;

FIGS. 3a through 3f are diagrams showing the waveforms of pulses generated at various portions of the control systems in the first through fourth embodiment, respectively;

FIG. 4 is a diagram showing the relationship between the pressure in the suction manifold of the internal combustion engine and the delay time of the pulses, under different atmospheric pressures, in the first through fourth embodiment;

FIG. 5 is a view showing, partially in section and partially schematically, the second embodiment of the control system according to the invention as applied to an internal combustion engine;

FIG. 6 is a view showing, partially in section and partially schematically, the third embodiment of the control system according to the invention as applied to an internal combustion engine;

FIG. 7 is a view showing, partially in section and partially schematically, the fourth embodiment of the control system according to the invention as applied to an internal combustion engine;

FIG. 8 is a transverse cross-sectional view of the variable circuit-length device of the fourth embodiment;

FIG. 9 is a diagram showing the relationship between the absolute pressure in the suction manifold of the intemal combustion engine and the pulse delay time in the fourth embodiment;

FIG. 10 is a diagram showing the relationship between the absolute pressure in the suction manifold of the internal combustion engine and the quantity of fuel to be supplied to the engine for each revolution thereof, in the fourth embodiment;

FIG. 11 is a view showing, partially in section and partially schematically, a fifth embodiment of the control system according to the invention as applied to an internal combustion engine;

FIG. 12 is a transverse cross-sectional view of the variable circuit-length device for the compensation of the atmospheric pressure, in the fifth embodiment;

FIGS. 13a through 13f are diagrams showing the waveforms of pulses generated at various portions of the control system in the fifth embodiment, respectivey;

FIG. 14 is a diagram showing the relationship between the absolute atmospheric pressure and the pulse delay time when the plunger of the variable circuit-length device moves, in the fifth embodiment; and

FIG. '15 is a diagram showing the relationship between the absolute pressure in the suction manifold of the internal combustion engine and the quantity of fuel to be supplied to the engine for each revolution thereof, under different atmospheric pressures, in the fifth embodiment.

The present invention will be described on five embodiments thereof sequentially as applied to an internal combustion engine mounted on a vehicle, such as an automotive vehicle, with reference to the accompanying drawings:

.FIGS. 1 and 2 show the first embodiment of the present invention. In these figures, reference numeral 1 designates a compressed air pump driven from an internal combustion engine or electric motor; 2 an airpressure regulating valve by which the pressure of the air discharged from the compressed air pump 1 is maintained constant; 3 a fluidic control circuit; 4 a fluidic multivibrator element consisting of a fluidic flip-flop element; 4a the power supply port of said element; 4b, 4c the control ports of said element; and 4d, 42 the output ports of said element. Reference numeral designates a variable circuit-length device and 5a designates a cylinder of said variable circuit-length device which has a helical groove 5b and an elongate groove 50 formed independently in the inner surface thereof. Reference numeral 5d designates a power supply port communicating with one end of said helical groove Sb-and also with the output port 4d of the multivibrator element 4. The pitch of the helical groove 5b is made smaller at the end portion remote from the power supply port 5d. Reference numeral 5e designates an output port of the variable circuit-length device 5, which communicates with said elongate groove 50 and also with the control port 4b of the multivibrator element 4. Reference numeral 5f designates a plunger axially slidably disposed in the cylinder 5a; 5g an annular port formed in the peripheral surface of the plunger 5f at a portion opposed by the helical groove 5b; 5h a port formed in the peripheral surface of said plunger 5f at a portion opposed by the elongate groove 50; and Si a passage formed in said plunger 5f and communicating said ports 5g, 5h with each other. Reference numeral Sj designates a power cylinder formed axially of the cylinder 5a integrally therewith and 5k designates a diaphragm disposed in said power cylinder 5j and dividing the interior of said power cylinder into a negative pressure chamber 5e and an atmospheric pressure chamber 5m. The negative pressure chamber Se is communicated with the suction manifold of the engine through a negative pressure introducing pipe 5n for introducing the manifold vacuum pressure thereinto, while the atmospheric pressure chamber 5m is communicated with the atmosphere through a communication port 50. The diaphragm 5k and the plunger 5f are connected with each other by a bolt 5p. Further, the diaphragm Skis urged toward the atmospheric pressure chamber 5m by a spring Sq disposed in the negative pressure chamber Se. Reference numerals 6a, 6b, 6c, 6d each designate a fixed fluidic resistance consisting, for example, of an orifice. Reference numeral 7 designates a fluidic monostable multivibrator element having a power supply port 70, a control port 7b and output ports 7c, 7d. The output port is communicated with the control port 40 of the multivibrator element 4 and the other output port 7d is opened into the atmosphere. Reference numeral 7' designates another fluidic monostable multivibrator having a power supply port 7a, a control port 7b and output ports 7'c, 7'd. The output port 7'c is communicated with a compressed air nozzle 25 to be described later. The arrangement is such that when a signal from the output port 4e of the multivibrator element 4 is applied to the control port 7b of the monostable multivibrator element 7, a signal equivalent to a signal generated at the output port 4d of said multivibrator element 4 is amplified and appears at the output port 7'c of the monostable multivibrator element 7'. At the output port 7d is generated a signal of a phase exactly reverse to that of the signal generated at the output port 7'c but this signal is released into the atmosphere. Reference numeral 8 designates a fluidic detector for detecting the rate -of rotation of the engine 9,which generates an air pulse signal synchronized with the rotation of said engine. The detector 8 includes a rotary body 10 and a member 11 abutting against said rotary body 10. The rotary body 10' rotates at the same rate as that, for example, of the cam shaft of the internal combustion engine 9 and makes one revolution on two revolutions of the crank shaft. Further, the rotary body 10 has circumferential grooves 11c, 11d formed at portions of the peripheral surface thereof and generates one pulse Pa, as shown in FIG. 3a on every revolution of the crank shaft. The member 11 has a power supply port 11a and an output port 11b formed therein toward the peripheral surface of the rotary body 10. The output port 11b is communicated with the control port 7b of the monostable multivibrator element 7. The detector 8 generates one output air pulse at its output port 1 lb only when the communication between the power supply port 11a and the output port 11b is established by each of the grooves 11c, 11d of the rotary body 10, and therefore, generates two air trigger pulses in each revolution of said rotary body 10. The compressed air pump 1 and the air pressure regulating valve 2 supply a constant pressure of compressed air to each of the power supply port 4a of the multivibrator element 4, the power supply ports 7a, 7'a of the monostable multivibrator elements 7, 7 and the power supply port 11a of the detector 8, and the pressure ratio of the compressed air supplied to said respective ports is adjusted by the fixed fluid resistances 6a, 6b, 6c.

Reference character A generally indicates the internal combustion engine 9 and devices associated with said engine, such as a fuel tank 29, a float chamber 28,

etc., which will be described hereunder: Reference numeral 14 designates a cylinder of the engine 9, 15 a piston, 16 an intake valve, and 17 an exhaust valve. Reference numeral 18 designates an intake passage communicating with the intake valve 16, 19 a suction manifold connected to the intake passage 18, and 20 a throttle valve provided in the downstream side of the suction manifold 19. Reference character 1 generally indicates a fuel injecting portion, in which reference numeral 21 designates a hood of a fuel injection chamber, 22 the fuel injection chamber, 23 a fuel injection nozzle projecting into said chamber 22, and 24 a tubular fuel receiving pipe projecting into the chamber 22. The fuel injection nozzle 23 and the fuel receiving pipe 24 are arranged in opposed relation to each other with a certain distance therebetween and substantially axially aligned with each other. Reference numeral 25 designates a compressed air nozzle projecting into the fuel injection chamber 22, with the axis thereof extending at right angles to a line connecting the tip ends of the fuel injection nozzle 23 and the fuel receiving pipe 24. A fuel return passage 26 has one end connected to the fuel receiving pipe 24, with the other end leading into the float chamber 28. Reference numeral 29 designates a fuel tank and 30 designates a pump by which fuel F in said fuel tank 29 is supplied into said float chamber 28 with pressure, 31 a fuel injection pump and 31a a battery constituting a power source for said pump 31. Reference numeral 32 designates a pressure regulating valve by which the discharge pressure of the pump 31 is maintained constant. The fuel F in the float chamber 28 is set to the fuel injection nozzle 23 at a predetermined pressure and a predetermined flow rate by the pressure regulating valve 32 and the fuel injection pump 31. Reference numerals 33a, 33b designate cam shafts to open and close the intake valve 16 and exhaust valve 17 respectively. Reference numeral 34 designates a negative pressure sensing port opened into the suction manifold 19 at a point downstream of the throttle valve 20 and communicating with the negative pressure introducing pipe 5n of the variable circuit-length device 5. The plunger 5f of the variable circuit-length device 5 and the throttle valve 20 operatively connected by a link mechanism 35 through a switching device 42 which operates on a special occasion, so that said plunger 5f may be operated on the special occasion according to the degree of opening of said throttle valve 20. The output port 7'c of the multivibrator element 7 is communicated with the compressed air nozzle 25. Reference numeral 36 designates a valve which senses an abrupt deceleration of the engine by way of the manifold vacuum pressure from the negative pressure sensing port 34 and interrupts the air pulse signal supplied from the detector 8 to the control port 7b of the monostable multivibrator element 7. Reference numeral 37 designates a valve which detects a malfunction of the compressed air pump 1 by way of presence or absence of the discharge pressure of said pump and interrupt the power supply to the fuel injection pump 31. Reference numeral 38 designates a check valve and 39 designates an air injection nozzle positioned with its axis extending toward the exhaust valve 17 and communicating with the discharge side of the compressed air pump 1. Reference numeral 13 designates an ignition switch of the vehicle and the fuel injection pump 31 is set in motion when said ignition switch 13 is closed.

The control system of the invention constructed as described above operates in the following manner: Namely, a constant pressure of compressed air is always supplied to the power supply port 4a of the multivibrator element 4, the power supply ports 7a, 7'a of the monostable multivibrator elements 7, 7' and the power supply port 11a of the rate of rotation detector 8 by the compressed air pump 1 and the air pressure regulating valve 2. When the air pulse signal Pa as shown in FIG. 3a, generated at the output port 11b of the detector 8 is applied to the control port 7b of the monostable multivibrator element 7 under such condition, said element 7 generates an air pulse of a width m, as shown in FIG. 3b, irrespective of the rate of rotation of the engine 9. The air pulse thus generated at the output port 7c is applied as a trigger signal to the control port 40 of the next stage multivibrator element 4, whereupon the compressed air entering the power supply port 4a of said element 4 is directed into the output port 4d and the output from said output port 4d is partially supplied to the power supply port 5d of the variable circuit-length device 5. The compressed air thus introduced into the variable circuit-length device 5 passes at the sonic velocity through a passage formed by the helical groove 5b, the annular port 5b, the passage 5i, the port 5h and the elongate groove 50, and reaches the output port 5e, with a time delay as determined by the length of said passage. Since the length of the passage Si is predetermined, the delay time is varied by the length of the helical groove 5b from the power supply port 5d to the annular port 5g (hereinafter referred to as effective length). The plunger 5f constantly moves according to the magnitude of the manifold vacuum pressure introduced into the negative pressure chamber 5e, and further moves on the special occasion according to the degree of opening of the throttle valve transmitted thereto through the link mechanism 35. Now, when the manifold vacuum pressure is introduced into the negative pressure chamber 5e through the negative pressure sensing port 34 and the negative pressure introducing pipe 5n, the diaphragm Skis attracted toward the negative pressure chamber 56 under the effect of negative pressure against the biasing force of the spring Sq, and accordingly the plunger 5f is moved in the direction of the arrow B,. The amount of movement of the plunger 5 f is proportional to the magnitude of the negative pressure introduced into the negative pressure chamber 5e. Upon movement of the plunger 5f in the direction of the arrow 8,, the annular port 5g is brought into communication with the helical groove 5b. Thus, it will be understood that the effective length of the passage becomes progressively short and hence the delay time becomes progressively small, as the negative pressure in the negative pressure chamber 5e becomes large. On the contrary, the effective length of the passage and, therefore, the delay time becomes progressively long as the negative pressure in the negative pressure chamber 5e decreases. The same operation as described above takes place also in the event when the plunger 5f is moved by the link mechanism 35. The relationship between the pressure P (mml-Ig) in the suction manifold 19 and the delay time ta (mm sec) of the curve indicated by reference character E represents the characteristic of the control system when the engine is operated on the horizontal ground where the atmospheric pressure is 760 mrnI-Ig. The pitch of the helical groove 5b is made small at the end remote from the power supply port 5d so that the gradient of curve E may be relatively gentle within the range of the pressure in the manifold 19 from 400 to 700 mmI-Ig but may be relatively sharp when the pressure exceeds 700 mmI-Ig. A curve indicated by reference character D represents the characteristic of the control system when the engine is operated on the high ground, such as in the mountains, where the atmospheric pressure is 660 mmI-Ig. As seen, the curve D is the curve E which is displaced to the left parallel to the axis of abscissa by a distance corresponding to 100 mmI-Ig. Reference symbol Max on the axis of ordinate indicates the point where the delay time of the pulse is longest, and Min indicates the point where the delay time is shortest. With the rate of rotation of the engine being constant, when pulses (each of a width of m,) delayed, for example, by times 1,, t t as shown in FIG. 3c, by the variable circuit-length device 5, are applied to the control port 4b of the monostable multivibrator element 4, the flow of compressed air which has been passing through the output port 4d, is directed into the output port 4e. When the pulse applied to the control port 4b is P shown in FIG. 3c, a compressed air pulse of Pd, shown in FIG. 3d is generated at the output port 4d. Similarly, when the pulse is P0 a compressed air pulse of Pe shown in FIG. 3e, and when the pulse is P0 a compressed air pulse of Pf shown in FIG. 3f, is generated at the output port 4d. The waveform of each pulse is rectangular and the period thereof is t The widths of the respective compressed air pulses Pd Pe Pf are determined by the delay time provided by the variable circuit-length device 5, i.e., the magnitude of the manifold vacuum pressure representing the size of the engine load, and are indicated by t t 1 respectively.

In order to follow the high speed operation of the engine,-it is necessary to increase the quantity of fuel supplied during one cycle of operation of the engine to the possible extent, by reducing the pulse interval and increasing the pulse width, even though the period of the pulse is short. If an arrangement is made such that a pulse Pc is generated when the delay time provided by the variable circuit-length device 5 is t and longest, as shown in FIG. 3f, and the falling point of this pulse becomes equal to the rising point of the output compressed air pulse Pb of the monostable multivibrator element 7, the pulse interval will become shortest and m, and the pulse width will become largest and t The sum of the maximum value t of pulse width and the minimum value m of pulse interval is the period of the pulse and this period is determined by the maximum rate of rotation of the engine. Therefore, the time which can be used for injecting the fuel can be made longest, even during the high speed operation of the engme.

At the output port 4e are generated compressed air pulses whose phases are reverse to those of the blown pulses generated at the output port 4d and shown in FIGS. 3d, 3e, 3f, respectively. When the compressed air pulses generated at the output port 4e are applied to the control port 7b of the monostable multivibrator element 7', amplified compressed air pulses of the same phases as those of the pulses shown in FIGS. 3d, 3e, 3f are generated at the output port 7 '0 respectively.

Where no compressed air pulses are generated at the output port 7c of the multivibrator element 7, a jet of fuel injection nozzle 23 flows entirely into the fuel receiving pipe 24 and returned to the float chamber 28 through the fuel return passage 26.

However, when a compressed air pulse appears at the output port 7c of the multivibrator element 7', said compressed air pulse is jetted from the compressed air nozzle 25, so that the fuel passing from the fuel injection nozzle 23 into the fuel receiving pipe 24 is deflected and atomized into the suction manifold 19 and the atomized fuel is injected into the cylinder 14 through the throttle valve 20. In order to obtain a suction gas of a predetermined fuel air ratio, it is only necessary to control the ratio between the product of the suction efficiency and the air density (which is proportional to the quantity of air sucked in. each cycle of the engine 9) and the pulse width, to be a predetermined value. In the present invention, the fuel air ratio is constantly controlled to be an optimum value by varying the quantity of fuel to be injected, according to the magnitude of the manifold vacuum pressure supplied into the negative pressure chamber 5e of the variable circuit-length device 5 through the negative pressure sensing port 34 and according to the degree of opening of the throttle valve 20 on a special occasion.

On the other hand, the compressed air from the compressed air pump 1 is supplied to the air injecting nozzle 39 through the check valve 38 and injected from said nozzle toward the exhaust valve 17. Therefore, the toxic gases, such as carbon monoxide and unburned hydrocarbons, contained in the exhaust gas are oxidized and rendered harmless which they are exhausted through the exhaust valve 17.

In decelerating the engine 9 quickly, the valve 36 is actuated to interrupt the air pulse supplied from the rate of rotation detector 8 to the control port 7b of the monostable multivibrator element 7. Therefore, the air flowing into the power supply port 4a of the multivibrator element 4 continuously discharged from the output port 4e, as no air pulses are supplied to the control port 40. Consequently, no output pulse signals are generated at the output port 7 'c of the monostable multivibrator element 7 and the fuel injected from the fuel injection nozzle 23 is entirely received in the fuel receiving pipe 24 to be returned to the float chamber 28. In other words, when the engine 9 is to be quickly decelerated, the fuel supply to the engine is stopped and the discharge of the exhaust gas is also stopped.

When the compressed air pump 1 fails, the compressed air pulse is no longer supplied to the compressed air nozzle 25 and therefore, the fuel injected from the fuel injection nozzle 23 is entirely received in the fuel receiving pipe 24 and returned to the float chamber 28. In this case, the fuel is continuously circulated and the fuel vapor is released into the atmosphere during circulation, which is not only dangerous but also causes pollution of the atmosphere. According to the invention, however, the valve 37 is actuated upon failure of the compressed air pump 1, to interrupt the current supply to the fuel injection pump 31 and thereby interrupt the fuel supply to the fuel injection nozzle 23.

In this embodiment, the signal generated at the output port 4d of the fluidic monostable multivibrator element 4 is amplified by the fluidic monostable multivibrator element 7' and the amplified signal of the same phase is obtained at the output port 7'c of said element 7', as described above. However, it should be understood that the output port 4d of said element 4 may be communicated directly with the air injection nozzle 25 to be described later, without providing the element 7'0, and in this case, the waveform of the pulse reaching the injection nozzle 25 unavoidably becomes deformed and weakened to some extent.

in the first embodiment of the control system according to the present invention which is constructed as described above, the output signal of the fluidic monostable multivibrator circuit passing through the feed back circuit is delayed by a time corresponding to the engine load, by varying the length of the helical passage according to the engine load and then applied to the control port of said monostable multivibrator element. The monostable multivibrator element performs its function depending upon whether the delayed output signal has arrived at the control port or not, and generates a compressed air pulse having a width corresponding to the engine load; In this way, it is possible to supply a quantity of fuel just enough to meet the demand of the engine continuously from a low speed operation to-a high speed operation of the engine according to the rate of rotation of said engine Further, the fluidic monostable multivibrator circuit operates depending upon whether the output signal delayed by the variable circuit-length device has arrived at the control port thereof. Therefore, the multistable operation is highly accurate and fast and the width of the output pulse of the fluidic monostable multivibrator circuit, i.e., the quantity of fuel injected can closely follow the engine load. Another excellent advantage is that a fluctuation of the pulse width can be avoided even if the monostable multivibrator circuit is designed with a certain degree of freedom. Furthermore, according to the instant invention the control system operates highly reliably and the entire system can be provided in a compact form, because the injection of fuel does not directly involve a mechanical moving part and none of the parts associating with the fuel injection particularly call for machining precision, and in addition, the fluidic elements are small in size and can be put together at one location, no additional works being required other than piping. Therefore, the control system of the invention is highly adapted for use with an internal comoustion engine of an automobile wherein the available space is particularly limited, makes it possible to prolong the useful life of the engine and can be provided at a low cost.

It should also be noted that, in the present invention, the minimum value of pulse interval of the output compressed air pulse signal of the second fluidic monostable multivibrator element can be reduced to a value equal to the pulse width of the output pulse of the first fluidic monostable multivibrator element. Therefore, by previously setting the output pulse of the first fluidic monostable multivibrator element at a small value, it is possible to make the aforesaid pulse interval very small and thereby to inject a quantity of fuel demanded by the engine, into the suction manifold continuously and uniformly, not only in the low speed, low load region but also the high speed, high load region of the engine, except for a very short period of time corresponding to the pulse interval. This is very advantageous in that a fuel injection pump of small capacity can be used at the fuel injecting portion and in that the quantity of fuel supplied to the respective cylinders of a multi-cylinder engine can be uniformalized.

The second embodiment of the invention will be described hereunder with reference to FIG. 5 in which same parts or devices as those used in the first embodiment are indicated by same reference numerals with added thereto. In FIG. 5, reference numeral 101 designates a compressed air pump driven from an internal combustion engine or an electric motor, 102 an air regulating valve by which the discharge air pressure of said compressed air pump 101 is maintained constant; 103 a fluidic control circuit; and 104 a fluidic monostable multivibrator element having a power supply port 104a, control ports 104b, 104e, 104a, an OR output port 104d and a NOR output port 104e. The output port 104d and the control port 1040 are communicated with each other by a pipe l04f for positive feed back, and the output port l04e is opened into the at mosphere. Reference numeral 105 designates a variable circuit-length device which is identical in construction with the variable circuit-length device 5 shown in FIG. 1. A power supply port 105d of the device 105 is communicated with a pipe communicating an output port 107c of a fluidic monostable multivibrator element 107 to be described later and the control port 104a of the monostable multivibrator element 104 with each other, and an output port 105e thereof is communicated with the control port 104b of said element 104. Reference numerals 106a, 106b, 106e, 106d designate fixed fluidic resistances, each consisting, for example, of an orifice, respectively. Reference numeral 107 designates a fluidic monostable multivibrator element having a power supply port 107a, a control port 107b and output ports 107e, 107d. The output port 107c is communicated with the control port 1046 of the monostable multivibrator element 4 and the other output port 107d is opened into the atmosphere. Reference numeral 108 designates a fluidic rate of rotation detector which generates an air pulse in synchronism with the rotation of the engine 109. The detector 108 is identical in construction with the detector 8 shown in FIG. 1 and is designed to generate one pulse Pa shown in FIG. 3a on every revolution of the crank shaft. An output port lllb of a member 111 is communicated with the control port 107b of the monostable multivibrator element 107. The compressed air pump 101 and the air pressure regulating valve 102 supply a constant pressure of compressed air to each of the power supply ports 104a, 107a of the monostable multivibrator elements 104, 107 and the power supply port 111a of the detector 108, and the pressure ratio of the compressed air supplied to said respective ports is adjusted by the fixed fluidic resistances 106a, 106b, 1060.

Reference character A generally indicates the internal combustion engine 109 and devices associated therewith, and the construction of the portion A is exactly identical with that of A, in FIG. 1. A compressed air nozzle 125 is communicated with the OR output port 104d of the monostable multivibrator element 104, and a negative pressure sensing port 134 is communicated with a negative pressure introducing pipe 105n of the variable circuit-length device 105. A plunger. 105f of the variable circuit-length device 105 and a throttle valve 120 are operatively connected with each other by a link mechanism 135 through a switching device 142 which is operated on a special occasion, so that said plunger lf may be operated on a special occasion according to the degree of opening of said throttle valve 120. The functions of valves 136, 137 are exactly the same as those of the valves 36, 37 in FIG. 1.

The second embodiment of the invention constructed as described above operates as follows: A constant pressure of compressed air is always supplied to the power supply ports 104a, 107a of the monostable multivibrator elements 104, 107 and the power supply port 1 1 1a of the detector 8 by the compressed air pump I01 and the air pressure regulating valve 102. When the air pulse signal Pa shown in FIG. 3a and generated at the output port lllb of the detector 108 on every revolution of the crank shaft is applied to the control port l07b of the monostable multivibrator element 107 as a trigger pulse, under such condition, said element 107 generates the air pulse Pb, of a pulse width tn, as shown in FIG. 3b, at its output port 1070 irrespectively of the rate of rotation of the engine 109. The air pulse generated at the output port 1070 is partially supplied as a trigger pulse to the control port 1040 of the next stage monostable multivibrator element 104, whereby the compressed air which has been flowing from the power supply port 104a into the NOR output port 104e, is directed into the OR output port 104d. The compressed air discharged from the OR output port 104d is partially supplied to the control port 1040 after restricting the flow rate by the fluidic resistance 106d. By so doing, the compressed air continues to flow through the OR output port 104d, even after the compressed air pulse supplied from the output port 1070 of the monostable multivibrator element 107 to the control port 1040 of the monostable multivibrator element 104 disappears. On the other hand, the compressed air pulse generated at the output port 1070 of the monostable multivibrator element 107 is partially supplied to the power supply port 105d of the variable circuitlength device 105. The compressed air pulse thus supplied passes at the sonic velocity through the passage formed by a helical groove 105b, an annular port 105g, a passage 105i, a port l05h and an elongate groove 1050, and reaches the output port 1050 with a delay time as determined by the length of said passage. Since the length of the passage 105i is predetermined, the delay time is varied by the length of the helical groove l05b from the power supply port 105d to the annular port 105g (hereinafter referred to as effective length). The effective length of the variable circuit-length device 105 is varied in the following manner: Namely, the plunger l05f constantly moves according to the magnitude of the manifold vacuum pressure introduced into a negative pressure chamber 151, and further moves on a special occasion according to the degree of opening of the throttle valve which is transmitted through the link mechanism 135. Now, when the manifold vacuum pressure is introduced into the negative pressure chamber 151 through the negative pressure sensing port 134 and the negative pressure introducing pipe n, a diaphragm 105k is attracted under suction toward the negative pressure chamber 151 against the biasing force of a spring 105q and accordingly the plunger l05f is also moved in the direction of the arrow B The amount of movement of the plunger 105f is proportional to the magnitude of the negative pressure introduced into the negative pressure chamber 151. Upon movement of the plunger 105f in the direction of the arrow 8,, the annular port 105g is shifted to a position to communicate with the helical groove 105b. Thus, it will be understood that the aforesaid effective length and hence the delay time becomes progressive short as the negative pressure in thenegative pressure chamber 151 becomes progressively large, and conversely becomes progressively long as the latter becomes progressively small. The abovedescribed operation similarly takes place when the plunger l05f is moved by the link mechanism 135. The relationship between the pressure P (mml-lg) in the suction manifold 119 and the pulse delay time ta (mm sec) is exactly the same as described previously with reference to the first embodiment and as shown in FIG. 4. With the rate of rotation of the engine being constant, when the pulses (each of a width of tn delayed, for example, by times t,, t t by the variable circuitlength device 105 as shown, for example, in FIG. 30, are applied to the control port 104b of the monostable multivibrator element 104, the compressed air flow which has been passing through the OR output port 104d, is directed into the NOR output port 1040. Therefore, if the pulse applied to thecontrol port 104b is P0 shown in FIG. 30, a compressed air pulse of Pd shown in FIG. 3d is generated at the output port 104d, and similarly, if the pulse is P0 or P0 a compressed air pulse of P0 or Pf shown in FIG. 30 or 3f appears at said port respectively. The widths of the pulses Pd Pe Pf, are the values of t t t which are determined by the delay times provided by the variable circuit-length device 105 or the magnitude of the manifold vacuum pressure representing the size of the engine load, respectively.

In order to follow the high speed operation of the engine, it is necessary to increase the quantity of fuel supplied during one cycle of operation of the engine to the possible extent, by reducing the pulse interval and increasing the pulse width, even though the period of the pulse is short. If an arrangement is made such that a pulse P0 is generated when the delay time provided by the variable circuit-length device 105 is t and longest, as shown in FIG. 3f, and the falling point of this pulse becomes equal to the rising point of the output compressed air pulse Pb, of the monostable multivibrator element 107, the pulse interval will become shortest and m,, and the pulse width will become largest and The sum of the maximum value t: of pulse width and the minimum value tn of pulse interval is the period of the pulse and this period is determined by the maximum rate of rotation of the engine. Therefore, the time which can be used for injecting the fuel can be made longest, even during the high speed operation of the engine.

At the output port 104e is generated a compressed air pulse of a phase reverse to the air pulse generated at the OR output port 104d but said compressed air pulse is released into the atmosphere.

However, when no compressed air pulses are generated at the OR output port 104d of the monostable multivibrator element 104, the fuel injected from a fuel injection nozzle 123 in the form of a jet flows entirely into a fuel receiving pipe 124 to be returned to a float chamber 128 through a fuel return passage 126.

Now, when a compressed air pulse is generated at the output port 104d of the monostable multivibrator element 104, said compressed air pulse is jetted from a compressed air nozzle 125, so that the fuel passing from the fuel injection nozzle 123 into the fuel receiving pipe 124 is deflected and atomized by said compressed air pulse and injected into the suction manifold 1 19 to be injected into a cylinder 1 14 through a throttle valve 120. In order to obtain a mixture of a desired fuel air ratio, it is only necessary to control the ratio between the product of the suction efficiency and the air density (which is proportional to the quantity of air sucked into the engine for each cycle of the engine), and the pulse width, to be a certain value. In this embodiment, the fuel air ratio is controlled to be an optimum value at all times, by varying the quantity of fuel to be injected in accordance with the magnitude of the manifold vacuum pressure introduced into the negative pressure chamber 151 of the variable circuit-length device 105 through the negative pressure sensing port 134, as described above.

As stated above, the rate of rotation detector 108 generates two of the pulse Pa shown in FIG. 3a during two revolutions of the crank shaft or one cycle of the engine. Therefore, two compressed air pulses are generated at the OR output port 104d of the monostable multivibrator element 104 in each cycle of the engine based on the pulse Pa and the width of said pulse corresponds to the size of the engine load. Particularly in the high speed, high load region of the engine, the waveform of the compressed air pulse generated at the OR output port 104d becomes close to the waveform shown in FIG. 3f, the pulse width becomes extremely wide and the pulse interval becomes extremely close to the value of m Namely, the fuel injected from the fuel injection nozzle 123 for one cycle of engine is almost entirely injected into the suction manifold 119 continuously by the compressed air pulse of an extremely wide width jetted from the compressed air nozzle, except for a short period of time corresponding to the pulse interval, and a very small quantity of fuel injected from the fuel injection nozzle 123 during said short period of time only is returned to the float chamber 128 through the fuel receiving pipe 124. Particularly, in the high speed, high load region of the engine, a quantity of fuel demanded by the, engine for one cycle of operation can be continuously uniformly injected into the suction manifold 119 during the period of one cycle, except for the aforesaid very short period of time. This makes it possible to use a pump of smaller capacity for a fuel injection pump 131 than the capacity of the pump required in the case when a quantity of fuel demanded by the engine is injected all at once for only a short period of time during one cycle of the engine. In addition, where the engine is a multi-cylinder engine, the

quantities of fuel to be supplied to the respective cylinders can be uniforrnalized. These advantages are particularly apparent in thehigh speed, high load region of the engine. Moreover, in the low speed, low load region of the engine, the fuel injection period can be shortened to tn, by shortening the pulse delay time to tn, and thereby the quantity of fuel to be injected can be minimized.

In this embodiment also, the toxic gases in the exhaust gas are oxidized and rendered harmless by the compressed air blown from an air injection nozzle 139 through a check valve 138; the fuel supply to the engine 109 is interrupted at the time of abrupt deceleration of the engine, by the operation of the valve 136; and the current supply to the fuel injection pump 131 is interrupted by the operation of the valve 137 upon failure of the compressed air pump 101, to interrupt the fuel supply to the fuel injection nozzle 123, as described previously with reference to the first embodiment.

In this embodiment, the power supply port d of the variable circuit-length device 105 is communicated with the pipe which communicates the output port l07c of the monostable multivibrator element 107 and the control port- 104c of the monostable multivibrator element 104 with each other, as stated above, but said power supply port 105d may be communicated directly with the output port 104d of said element 104.

Because of the construction described above, the second embodiment of the control system has the same effects as those of the first embodiment described previously.

An additional advantage of this embodiment is that, since the compressed air pulse generated at the OR output port of the second monostable multivibrator element is supplied to the fuel injecting portion, even if an electrically operated compressor is used for supplying compressed air to said second multivibrator element and compressed air is continuously supplied to said power supply port during the period when the engine is not operated, such compressed air flows into the NOR output port and not into the OR output port, and therefore, gives no detrimental effect on the system at all.

The third embodiment of the invention will be described hereunder with reference to FIG. 6 wherein same members or devices as those of the first embodiment shown in FIG. 1 are indicated by the same reference numerals with 200 added thereto, respectively. In FIG. 6, reference numeral 201 designates a compressed air pump driven from an internal combustion engine mounted on a vehicle; 202 an air regulating valve by which the discharge air pressure of said compressed air pump 201 is maintained constant; 203 a fluidic control circuit; and 204 a fluidic bistable multivibrator element consisting of a fluidic flip'flot element and having a power supply port 204a, control ports 204b, 2040, and output ports 204d, 2041:. One of the output port 204e is opened into the atmosphere. Reference numeral 205 designates a variable circuitlength device which is identical in construction with the variable circuit-length device 5 shown in FIG. 1. An input port 205d of the variable circuit-length device 205 is communicated with a pipe which communicates an output port 207a of a fluidic monostable multivibrator element 207 to be described later and the control port of the bistable multivibrator element 204 with each other, and an output port 205e thereof is communicated with the control port 204b of said element 204. Reference numerals 206a, 206b, 206e, 206d designate fixed fluidic resistances each consisting, for example, of an orifice. Reference numeral 207 designates a fluidic monostable multivibrator element having a power supply port 207a, a control port 207b and output ports 207c, 207d. The output port 2070 is communicated with the control port 2040 of the multivibrator element 204 and the other output port 207d is opened into the atmosphere. Reference numeral 208 designates a fluidic rate of rotation detector which generates an air pulse signal in synchronism with the rotation of the engine and is of exactly the same construction as the detector 8 shown in FIG. 1. Namely, the detector 208 generates one pulse Pa shown in FIG. 3a on every revolution of the crank shaft. An output port 211b of a member 211 is communicated with the control port 207b of the monostable multivibrator element 207.

A predetermined pressure of compressed air is supplied by the compressed air pump 201 and the air pressure regulating valve 202 to each of the power supply port 204a of the bistable multivibrator element 204, the power supply port 207a of the monostable multivibrator element 207 and a power supply port 211a of the detector 208, and the ratio of the compressed air pressure supplied to said respective ports is adjusted by the fixed fluidic resistances 206a, 206b, 2060, 206d.

Reference character A generally indicates the engine 209 and devices associated therewith, and the construction of the portion A, is exactly the same as that of A shown in FIG. 1. A compressed air nozzle 225 is communicated with the output port 204d of the bistable multivibrator element 204, and a negative pressure sensing port 234 is communicated with a negative pressure introducting port 205n of the variable circuitlength device 205.

A plunger'205f of the variable circuit-length device 205 and a throttle valve 220 are operatively connected by a link mechanism 235 through a switching device 242 which is operated on a special occasion, so that said plunger 205f is moved on a special occasion in accordance with the degree of opening of said throttle valve 220. The functions of valves 236, 237 are same as those of the valves 36, 37 shown in FIG. 1.

Now, the operation of this embodiment of the invention will be described. As stated, a predetermined pressure of compressed air is constantly supplied to each of the power supply port 204a of the bistable multivibrator element 204, the power supply port 207a of the monostable multivibrator element 207 and the power supply port 211a of the rate of rotation detector 208 from the compressed air pump 201 and the air pressure regulating valve 202. When the air pulse signal Pa shown in FIG. 3a and generated at the output port 21 lb of the detector 208 on every revolution of the crank shaft is applied to the control port 20711 of the monostable multivibrator element 207 as a trigger pulse under such condition, an air pulse Pb, of a width tn as shown in FIG. 3b is generated at the output port 2070 of said element 207 irrespectively of the rate of rotation of the engine. The air pulse thus generated at the output port 207c is applied as a trigger pulse to the control port 204a of the bistable multivibrator element 207, whereupon the compressed air flow passing through the power supply port 204a of said bistable multivibrator element 207 is directed into the output port 204d. The air pulse supplied to the control port 2040 is partially supplied to a power supply port 205d of the variable circuit-length device 205. The air pulse thus supplied passes at the sonic velocity through a passage formed by a helical groove 205b, an annular port 205g, a passage 205i, a port 205k and an elongate groove 205s, and reaches an output port 205e with a time delay as determined by the length of said passage. Since the length of the passage 205i is predetermined, the delay time is varied by the length of the helical groove 205b from the power supply port 205d to the annular port 205g (hereinafter referred to as effective length). The plunger 205f constantly moves according to the magnitude of the manifold vacuum pressure introduced into a negative pressure chamber 251, and further moves on a special occasion according to the degree of opening of the throttle valve transmitted thereto through the link mechanism 235. Now, when the manifold vacuum pressure is introduced into the negative pressure chamber 251 through the negative pressure sensing port 234 and the negative pressure introducing port 205n, a diaphragm 205k is attracted toward said negative pressure chamber 251 by the effect of vacuum pressure against the biasing force of a spring 205q, and'accordingly the plunger 205f moves in the direction of the arrow B The amount of movement of the plunger 205f is proportional to the magnitude of the negative pressure introduced into the negative pressure chamber 251. Upon movement of the plunger 205f in the direction of the arrow B the annular port 205g is displaced to a position to communicate with the helical groove 205b. Therefore, the aforesaid effective length and hence the delay time becomes progressively short as the negative pressure in the negative pressure chamber 251 increases, and conversely becomes progressively long as the latter decreases. The same operation as described above takes place also when the plunger 205f is moved by the link mechanism 235. The relationship between the pressure P (mmHg) in the suction manifold 219 and the pulse delay time is as shown in FIG. 4 and exactly the same as previously described with reference to the first embodiment.

With the rate of rotation of the engine being constant, when the pulses delayed by the variable circuit- Iength device 205, for example, by times 2 t as shown, for example, in FIG. 3c (the width of the pulses being all tn are applied to the control port 204b of the bistable multivibrator element 204, the compressed air flow which has been flowing into the output port 204d, is directed into the output port 204e. Therefore, if the pulse applied to the control 204b is Pc shown in FIG. 30, a compressed air pulse of Pd, shown in FIG. 3d is generated at said output port 204e. Similarly, if the pulse is Pc or P0 a compressed air pulse of Pe or Pf shown in FIGS. 3e or 3f respectively is generated at said output port 204e, and the widths of said respective pulses Pd Pe Pf are the values of t t t respectively which are determined by the delay time provided by the variable circuit-length device 205 or the manifold vacuum pressure representative of the size of the en gine load.

Claims (7)

1. A control system for a fuel injection device of internal combustion engines, comprising trigger pulse generating means for generating a trigger pulse in synchronism with the rotation of an internal combustion engine, variable circuit-length means by which the length of a fluid passage can be varied according to the load on said engine and fluidic control circuit for generating a fluidic pulse of a variable width and a variable number in cooperation with said variable circuit-length means and said trigger pulse generating means, the trigger pulse generated by said trigger pulse generating means being applied to said fluidic control circuit and said variable circuit-length means, whereby a fluidic pulse is generated by said fluidic control circuit, which is used for controlling the quantity of fuel supplied to said engine.

2. A control system for a fuel injection device of internal combustion engines, according to claim 1, wherein said fluidic control circuit includes a multivibrator element, and said variable circuit-length means is inserted in a negative feed back circuit of said element or in a circuit by which a pipe for applying the trigger pulse to a first control port of said element therethrough communicates with a second control port of said element.

3. A control system for a fuel injection device of internal combustion engines, according to claim 2, wherein said trigger pulse generating means includes a rate of rotation detecting unit adapted to generate a pulse by intermittently interrupting a fluid passage and a monostable multivibrator element for shaping the output pulse of said rate of rotation detecting unit.

4. A control system for a fuel injection device of internal combustion engines, according to claim 3, wherein said monostable multivibrator element included in the trigger pulse generating means is a one-shot monostable multivibrator element and said multivibrator element included in the fluidic control circuit is a bistable multivibrator element.

5. A control system for a fuel injection device of internal combustion engines, according to claim 3, wherein said monostable multivibrator element included in the trigger pulse generating means is a one-shot monostable multivibrator element and said multivibrator element included in the fluidic control circuit is an OR-NOR monostable multivibrator element.

6. A control system for a fuel injection device of internal combustion engines, according to claim 4, wherein said fluidic control circuit further includes a monostable multivibrator element for amplifying the output pulse of said bistable multivibrator element.

7. A control system for a fuel injection device of internal combustion engine, comprising trigger pulse generating means for generating a trigger pulse in synchronism with the rotation or an internal combustion engine, first variable circuit-length means by which the length of a fluid passage can be varied according to the load on the engine, second variable circuit-length means by which the length of a fluid passage can be varied according to the atmospheric pressure, and fluidic control circuit for generating a fluidic pulse of a variable width and a variable number in cooperation with said first and second variable circuit-length means and said trigger pulse generating means, the trigger pulses generated by said trigger pulse generating means being applied, one to said fluidic control circuit through said second variable circuit-length means and the other one to said fluidic control circuit and said first variable circuit-length means, whereby a fluidic pulse is generated by said fluidic control circuit, which is used for controlling the quantity of fuel supplied to said engine.

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