Omori, Norio (Kariya, JA)
Oiwa, Katsuhiko (Handa, JA)

05/342983

07/29/1975

03/20/1973

Download PDF 3896779       PDF help

Click for automatic bibliography generation

Nippondenso Co., Ltd. (Kariya, JA)

123/483

123/198F, 123/458, 123/499, 123/449, 123/481, 123/358

F02D41/36; F02D41/40; F02M41/12; F02M59/36; F02M63/02; F02B75/02; F02D41/32; F02M41/08; F02M59/20; F02M63/00; F02M63/02

123/32AE,32EA,198F,139E

3699935	FAIL-SAFE FUEL INJECTION CONTROL ARRANGEMENT FOR INTERNAL COMBUSTION ENGINES	October 1972	Adler et al.
3724436	FUEL FEED CONTROL DEVICE FOR INTERNAL COMBUSTION ENGINES	April 1973	Nagata et al.
3734067	FUEL INJECTION SYSTEM FOR INTERNAL COMBUSTION ENGINE	May 1973	Glocker et al.
3736910	CONTROL CIRCUIT FOR CONTROLLING A FUEL INJECTING SYSTEM	June 1973	Raff
3756205	METHOD OF AND MEANS FOR ENGINE OPERATION WITH CYLINDERS SELECTIVELY UNFUELED	September 1973	Frost

Myhre, Charles J.

Argenbright, Tony

Cushman, Darby & Cushman

1. A fuel injection pump for an internal combustion engine having a cylinder provided with a suction passage and a suction port, a piston rotatably and reciprocally received in the cylinder, a compression chamber enclosed by the cylinder and the piston, and the suction port being open during the suction stroke to the compression chamber and being closed during the compression and injection stroke of the piston, the improvement comprising:

2. A fuel injection pump for an internal combustion engine as defined in claim 1 wherein said electromagnetic valve comprises:

BACKGROUND OF THE INVENTION

This invention relates to a fuel injection pump for an internal combustion engine and more particularly to a distributor-type fuel injection pump having an electronic fuel control device for a multiple-cylinder diesel engine. The electronic fuel control device comprises the electromagnetic valve and the controller, and the opening or closing operation of the valve is controlled by the controller so as to inject optimum amounts of fuel into specific cylinders to reduce stimulus odor.

In a conventional internal combustion engine having a distributor-type fuel injection pump, hydro-carbons with the stimulus odor of the exhaust gas increases in idling operation, because the quantity of the fuel injected into each cylinder is not large enough to keep the temperature of each combustion chamber high in idling operation. Because of the fact mentioned above, while it is known that the stimulus odor in idling operation diminishes as the temperature in the combustion chamber rises by increasing the quantity of the fuel injected into the chamber, the revolution of the engine exceeds the suitable speed for idling operation, e.g., such speed as 400 r.p.m. - 600 r.p.m., while the stimulus odor of the exhaust gas can be reduced.

SUMMARY OF THE INVENTION

With a view to overcoming the problem described above, it is a primary object of the present invention to provide an improved and simple fuel injection pump which has an electronic fuel control device and which supplies enough fuel into certain cylinders while stopping the fuel supply to the other cylinders when the engine is in idling operation to raise the temperature in the combustion chamber, thereby reducing the stimulus odor of the exhaust gas.

The above and other objects, features and advantages of the present invention will be apparent from the following detailed description of a preferred embodiment thereof taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a cross section of an embodiment of the present invention.

FIG. 2 shows an electronic circuit diagram of a controller of FIG. 1.

FIG. 3 shows the output voltage curves of the controller illustrated in FIG. 2 in normal operation.

FIG. 4 shows the output voltage curves of the controller illustrated in FIG. 2 in idling operation.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 1 which shows a distributor-type fuel injection pump, 1 designates a cylinder, 3 a spring, 4 designates a push rod which is integrally constructed with the piston 2, and the spring 3 is inserted between the cylinder 1 and the push rod 4. A drive shaft 15 is provided below the push rod 4 to rotate and reciprocate the push rod 4 thereby causing the suction stroke, injection stroke and discharge stroke of the pump. The piston 2 has a vertical passage 5, a horizontal passage 6 which leads to the vertical passage 5, an overflow groove 7 in which the horizontal passage 6 opens and a distributing groove 22. In the cylinder 1, there is bored an overflow passage 8, a suction passage 9 and ejection passages 10 which are equal in number to the number of the cylinders of the engine. The suction passage 9 leads to an electromagnetic valve 11 and the ejection passages 10 lead to discharge valves 12 which are to be connected to the injection valves (not shown) of the engine. 13 designates a compression chamber formed on the head of the piston 2. The suction port 9a does not open into the compression chamber 13 when the piston 2 is in the compression and injection stroke. 14 designates a fuel passage which leads to a fuel pump (not shown) to supply compressed fuel with constant pressure from a fuel tank (not shown). The drive shaft 15 is rotated by the engine 28. For example in the case that the engine is a 4 cycle engine, the shaft 15 rotates at a half speed of the engine crank shaft. 16 designates a holder fixed to a housing 17 by a bolt 18 and this holder 16 suspends pins 20 of rollers 19. An upper portion 15a of the drive shaft 15 is coupled with a coupling 21 of a cam 4a formed together with the push rod 4 so as to rotate the cam 4a with slidable movement thereof in the vertical direction. The cam 4a is provided with crest portions 4b and through portions 4c and the combined motion of the cam 4a with the rollers 19 causes the reciprocation of the piston 2. The construction of the electromagnetic valve 11 is as follows; i.e., 23 designates a coil, 24 an armature which is connected to a valve member 25, and return spring 26. When the coil 23 is energized, the armature 24 and the valve member 25 move toward the left of FIG. 1 to open the fuel passage 14 to the suction passage 9. 27 designates an electronic controller which controlls the energization of the coil 23 to thereby control the opening of the valve member 25.

The construction of the controller 27 is illustrated in FIG. 2. Referring now to FIG. 2, 101 designates a contact breaker which opens and closes in synchronism with the pump operation at the frequency corresponding to the number of the cylinders of the engine in one revolution of the drive shaft 15. 102, 103, 104 and 105 designate resistors, 106 a transistor. 107 designates a flip-flop circuit of a well-known type, 109 a variable resistor which varies the resistance in accordance with the depression of the accelerator (not shown). 112a and 112b designate switches which operate between the positions shown in full line and dotted line. 113 designates a pulse generator such as a monostable multivibrator the output of which is connected to the base of a transistor 115 through a resistor. The coil 23 of the electromagnetic valve 11 is connected between the collector of the transistor 115 and the plus terminal of a battery designated as 116.

Now, the operation of the mechanical construction of the present invention shown in FIG. 1 is explained. When the piston 2 goes down below the position shown in FIG. 1 and the suction passage 9 is opened into the compression chamber 13 at the suction port 9a; the fuel sent from the fuel pump is supplied into the compression chamber 13 through the fuel passage 14, the electromagnetic valve 11, the suction passage 9 and the suction port 9a, with the valve 25 being opened by an output signal from the controller 27 as explained in detail later. Then, as the piston 2 goes upwards, the top edge thereof closes the suction port 9a and the fuel confined in the compression chamber 13 is compressed finally to be ejected from one of the discharge valves 12, for example from the discharge valve 12 shown in the right hand side in FIG. 1. Hereupon, the beginning of the fuel ejection from the discharge valve 12 varies according to the quantity of the fuel ejected, i.e., it advances when the quantity is large and delays when the quantity is small because of the spring action in the discharge valve 12. Since the fuel is compressed after the piston 2 has closed the suction port 9a, it is possible to provide a small return spring 26 and consequently, a small powered electromagnetic valve 11. Subsequently, the piston 2 goes continuously upwards and then the top edge of the overflow groove 7 meets to the overflow passage 8. At that time, the compressed fuel in the compression chamber 13 is discharged into the overflow passage 8 through the vertical passage 5, the horizontal passage 6 and the overflow groove 7. Consequently, the discharge valve 12 closes to cease the ejection of the fuel. Since the ending of the ejection is equal to the time when the overflow groove 7 meets the overflow passage 8, the rotational angle of the cam 4a at the end of the ejection is constant in every cycle.

Next, the operation of the controller 27 which controlls the electromagnetic valve 11 is explained. Referring to FIGS. 2 and 3, in ordinary operation of the engine, i.e., when the operation of the engine is not in idling, the switch 112a is at the position shown in dotted line and the switch 112b is at full line. As the transistor 106 becomes conductive or nonconductive in accordance with the operation of the contact breaker 101, the voltage at the point v ₁ in FIG. 2 varies like the graph v ₁ in FIG. 3. As the switch 112a is at the position shown in dotted line, the voltage at the point v ₂ in FIG. 2 varies like the graph v ₂ in FIG. 3. The voltage signal v ₂ is fed as an input to the pulse generator 113. Since this pulse generator 113 is a monostable multivibrator as mentioned above, this generator 113 produces pulses whose leading edges correspond to the leading edges of the voltage signal v ₂ at the point v ₃ in FIG. 2. The foregoing pulses are illustrated in the graph v ₃ in FIG. 3. Then, as the resistance of the variable resistor 109 varies in accordance with the position of the accelerator, the width t ₁ of the pulse varies in accordance with the depression of the accelerator. Consequently, the variable-width pulses are fed to the coil 23 to move the armature 24 and the valve member 25 toward the left to open the valve 11 during the time corresponding to the width t ₁ . On the other hand, in idling operation of the engine, the switch 112a is at the position shown in full line and the switch 112b is at dotted line. The output of the transistor 106 is fed to the pulse generator 113 by way of the flip-flop circuit 107, so the frequency of the pulse at the point v ₂ in FIG. 2 becomes half of the frequency of the pulse at the point v ₁ as illustrated in the graph v ₂ in FIG. 4. And then, the pulse generator 114 produces such pulses as illustrated in the graph v ₃ in FIG. 4 on the point v ₃ in FIG. 2. At this state, as the resistance of the variable resistor 111 connected to the generator 113 is varied manually, the width t ₂ of the pulse produced by the pulse generator 113 is controlled only manually, not by the depression of the accelerator. The fuel quantity corresponding to the pulse width t ₂ is supplied only to the half of the total number of the engine cylinders.

As the present invention is constructed as above-described, the pump can supply the enough quantity of the fuel only into half number of the engine cylinders in idling operation with the simple construction. This means that even in idling operation, the temperature in the cylinders into which the fuel is supplied can be kept high enough thereby to cause the reduction of the stimulus odor of the exhaust gas.