JPS6114334B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pressure control valve in an electronically controlled fuel injection system for an automobile engine.

An electronically controlled fuel injection system is a device that precisely controls the fuel supplied to the engine using a computer instead of a carburetor.
The pressure control valve used as a component of the device maintains the fuel pressure applied to the injector constant and returns excess fuel to the fuel tank via the return pipe. by the way,
During cold periods, it is not possible to obtain good starting performance with just the fuel pressure applied to the injector, so a separate cold start injector is installed to improve starting performance, but this method complicates the entire system and increases cost. It's also expensive.

In order to eliminate such a problem, an object of the present invention is to provide a piston that is controlled to open and close by energizing a solenoid, close the piston when it is cold to prevent excess fuel from returning to the fuel tank, and prevent excess fuel from flowing into the injector. The present invention aims to provide a pressure control valve that improves starting performance by increasing fuel pressure.

Hereinafter, one embodiment of the present invention will be described based on the accompanying drawings.

The pressure control valve shown in FIG.
The external shape is formed by integrally connecting the second body 12 and the second body 12. The first body 11 is provided with a negative pressure introduction port 14, and the second body 12 is provided with an input port 15 and an output port 16, respectively. Further, a holder 17 is provided passing through the second body 12. A diaphragm 18 is clamped between the first body 11 and the second body 12, and its inner peripheral portion 18b is clamped between a pressure plate 19 and a retainer 20 fixed to the pressure plate 19. has been done. the diaphragm 18 and the pressure plate 19
Inside the first body 11 there is a first
A chamber 21 is provided inside the second body 12.
2 are formed respectively. The first chamber 21 includes the first
A spring 23 is stretched between the upper inner wall 11a of the body 11 and the pressure plate 19, and is biased downward. A valve 24 is disposed inside the pressure plate 19, and the valve 24 is brought into contact with the upper end portion 17a of the holder 17 by the downward biasing force of a spring 25. Thus, the upper end 17a of the holder 17 serves as a valve seat. A bush 26 made of a material with a small coefficient of friction is press-fitted into the inner circumference of the pressure plate 19, and the upper end surface 26a of the bush 26 comes into contact with the valve 24 in conjunction with the displacement operation of the pressure plate 19. The valve 24 is brought into an open state by further pushing the valve 24 up. Further, since the bush 26 has a small coefficient of friction, it can smoothly operate against the outer circumferential surface of the holder 17.
A piston 27 is provided inside the second body 12, and a flange 27a of the piston 27 is biased rightward by a spring 28 and comes into contact with the first lower end 17b of the holder 17. A solenoid 29 is provided approximately concentrically with the piston 27 on the outer periphery of the spring 28 and inside the second body 12, and when the solenoid 29 is excited by a current applied from the connector 29a. The piston 28 moves to the left against the spring 28, and the tip 27b of the piston 27 comes into contact with the second lower end 17c of the holder 17, causing the remainder flowing from the second chamber 22 through the passage 17d. Excessive fuel is prevented from exiting the output port 16. The flange 12a of the second body 12 is engaged with the flange 30a of the delivery pipe 30, and the low recess 12b of the second body 12 communicates with the inside of the delivery pipe 30 and its oil passage hole 30b. ing.

An example in which the above embodiment is applied to an electronically controlled fuel injection device will be described.

When the ignition switch 95 is turned on in FIG. 2, the fuel pump 60 starts operating and fuel is pumped from the fuel tank 40 through the low pressure fuel filter 50. Fuel discharged from the fuel pump 60 is sent to the engine room through a pressure line (high pressure side pipe) 80. In the engine compartment, fuel passes through a high-pressure fuel filter 51 and is distributed to each injector 70 by a delivery pipe 30, and is simultaneously sent to the pressure control valve 10 of the present invention shown in FIG. The fuel sent to the pressure control valve flows from the oil passage hole 15 to the second chamber 2.
3 will be introduced. As will be explained later, the pressure control valve 10 has the function of keeping the fuel pressure between the fuel pump 60 and the pressure control valve 10 at a constant pressure, and returning excess fuel from the output port 16 to the fuel tank 40 through the return pipe 32. It is something that does. The injector 70 opens a solenoid valve therein in response to a signal from the computer 110 to accurately measure and inject fuel into the intake manifold 90. Since the negative pressure introduction port 14 of the pressure control valve 10 communicates with the intake manifold 90, the first chamber 21 forms a negative pressure chamber.

With the above configuration, the effects of the pressure control valve 10 will now be explained.

The fuel injection time of the injector 70 is uniquely determined by the amount of air per cycle, regardless of the negative pressure of the intake manifold 90. Therefore,
In order to obtain a constant air-fuel ratio, it is necessary to always maintain the differential pressure across the injector 70 constant. For this purpose, the back pressure of the diaphragm 18 of the pressure control valve 10, that is, the negative pressure of the intake manifold 90 is introduced into the first chamber 21. Therefore, the pressure control valve 10 regulates the fuel pressure applied to the injector 70 to a predetermined value based on the pressure difference with the intake manifold 90. Now, fuel pump 6
When the pressure difference between the negative pressure of the intake manifold 90 and the negative pressure of the intake manifold 90 of the fuel discharged from 0 and introduced into the second chamber 22 of the pressure control valve 10 reaches a predetermined value, the biasing force of the spring 25 is overcome and the diaphragm 18
A pressure plate 19 integrated with the holder is moved upwardly. In conjunction with the displacement operation of the pressure plate 19, the upper end surface 26a of the bush 26 after a predetermined stroke (S) comes into contact with the valve 24 and further pushes up the valve 24, thereby urging it from the closed position to the open position. do. At this time, excess fuel in the second chamber 22 is returned to the fuel tank 40 from the output port 16 through the return pipe 32 via the passage 17a. However, when starting cold, the excess fuel
Since the fuel pressure is not returned to , the fuel pressure increases and the amount of injection from the injector 70 is increased for a predetermined period of time, thereby improving startability. That is, in the case of a cold start, that fact is detected by the water temperature sensor 10.
0 to the computer 110, the computer 110 closes the power supply circuit and connects the connector 29.
Current is conducted to the solenoid 29 via a.
At this time, the current flows for a specified time by the time switch 120. Then, the solenoid 29 is excited and the piston 27 moves to the left, causing the tip 27 of the piston 27 to move to the left.
b comes into contact with the second lower end portion 17c of the holder 17 and blocks communication between the passage 17a and the output port 16. As a result, the fuel pressure is increased and the amount of injection from the injector 70 is increased, making it possible to improve cold startability.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an embodiment of a pressure control valve according to the present invention, and FIG. 2 is a system diagram of an example in which the embodiment shown in FIG. 1 is applied to an electronically controlled fuel injection device. 10: Pressure control valve, 11, 12: Body, 1
4: Negative pressure introduction port, 15: Input port, 16:
Output port, 17a: Valve seat, 18: Diaphragm, 19: Pressure plate, 21: First chamber, 22:
2nd chamber, 23: first spring, 24: valve,
25: Second spring, 26: Bush, 27:
Piston, 29: Solenoid.

Claims (1)

[Claims] 1 A body equipped with an input port, an output port, and a negative pressure introduction port, a first chamber and a second chamber separated and formed in the body by a diaphragm that forms a pressure receiving part for fuel pressure, and a a first spring tensioned in the first chamber when a pressure difference between the fuel pressure introduced from the input port and the negative pressure introduced into the first chamber from the negative pressure introduction port reaches a predetermined value; a pressure plate that operates to displace integrally with the diaphragm by overcoming the biasing force of the second spring; and a means for opening the valve from the valve seat by overcoming the biasing force of a second spring after the pressure plate has operated a predetermined stroke displacement; In the pressure control valve, excess fuel is discharged from the second chamber through the output port when the valve is opened, and the pressure control valve is driven by a solenoid that is excited in response to an input electric signal to connect the second chamber and the output. A pressure control valve characterized in that it is provided with a piston that communicates with and shuts off communication with a port, and that the piston performs a shutoff operation when it is cold and a communication operation when it is not cold.