JPS6214369Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a fuel pressure control device for a fuel injection type internal combustion engine.

In vehicles equipped with this type of internal combustion engine, fuel vapor is generated in the fuel system when driving at high speeds when the atmospheric temperature is high or when driving uphill. When the engine is running, there is no problem because the paper is swept away by the flow of fuel (liquid) before it increases, and is supplied along with the fuel from the fuel injector to the combustion chamber, or returned to the fuel tank via the fuel pressure control device. , a large amount of vapor is generated near the fuel pump when the engine is stopped at high temperatures. Therefore, when the engine is restarted, the fuel pump becomes idling (vapor lock) due to the vapor filling the fuel pump, making it impossible to send fuel. The reason for this is that because the fuel pressure on the downstream side of the fuel pump is high, the fuel pump discharges only the vapor that has filled the vicinity, causing it to idle.

An object of the present invention is to prevent a fuel pump from being unable to discharge fuel due to vapor lock in a fuel injection internal combustion engine, and to improve restartability of the engine at high temperatures.

The present invention relates to a fuel pressure control device for a fuel injection type internal combustion engine, in which fuel supplied from a fuel pump is introduced into a diaphragm chamber on the other side of a first diaphragm, one side of which is subjected to the negative pressure of the intake pipe and the pressure of a first spring, and the fuel pressure pushes the diaphragm aside to open a first opening of a fuel return pipe and return the fuel to a fuel tank, thereby controlling the pressure of the fuel injected from the fuel injection device. A passage branching from the fuel return pipe is opened into the diaphragm chamber through an opening/closing valve by a second opening, the second opening is made to face one side of a second diaphragm on which the fuel pressure of the diaphragm chamber acts, the pressure of the second spring is applied to the other side of the second diaphragm, and the first and second springs are adjusted so that the set pressure when the second opening is opened is lower than the set pressure when the first opening is opened.
6, 26 and opening the on-off valve when the internal combustion engine is stopped.

Embodiments of the present invention will be described below based on the accompanying drawings.

In FIG. 1, fuel (gasoline) supplied from a fuel tank 1 by a fuel pump 2 is supplied to the fuel injector of each cylinder through a delivery pipe 3, and is injected from there into the engine combustion chamber.
A larger amount of fuel is supplied to the pressure regulator (fuel pressure control device) than the fuel supplied to the fuel injector.
The diaphragm chamber 12 is filled from the suction port 11 of 10. Intake manifold negative pressure acts on one chamber 14 partitioned by the diaphragm 13 from a negative pressure port 15, and at the same time a compression spring 16 is provided to push the diaphragm 13 toward the diaphragm chamber 12. A valve 17 is attached to the diaphragm 13 to open and close an opening 19 of a fuel return pipe 18 penetrating into the diaphragm chamber 12. That is, when the pressure of the fuel sucked into the diaphragm chamber 12 reaches the set pressure determined by the intake manifold negative pressure and the compression spring 16, the fuel pushes up the diaphragm 13 and the valve 17, opens the opening 19, and passes through the return pipe. It returns to the fuel tank 1 via 18. When the fuel pressure decreases by the set pressure, the diaphragm 1 is compressed by the compression spring 16.
3 and valve 17 are pushed down to close opening 19. Due to this action, fuel is injected at a constant pressure from the fuel injector provided in the intake manifold of each cylinder.

As shown in FIG. 1, another diaphragm chamber 20 is provided within the diaphragm chamber 12, and an opening 22 of a passage 21 branched from the return pipe 18 in the first diaphragm chamber 12 is connected to a second diaphragm chamber 20. It is designed to be opened and closed by a valve 24 of a diaphragm 23. Further, the same side of the second diaphragm 23 as the passage opening 22 receives the pressure of the fuel in the first diaphragm chamber 12, and the second diaphragm chamber 20 on the opposite side receives the pressure of the fuel, and a compression spring 26 is provided in the second diaphragm chamber 20 on the opposite side. is communicated with. compression spring 2
The set pressure 6 (the pressure when the valve 24 is opened) is much smaller than the set pressure (the pressure when the valve 17 is opened) determined by the first compression spring 16 and the intake manifold negative pressure.

An on-off valve 28 such as a solenoid valve is provided in the passage 21 within the diaphragm chamber 12 . This solenoid valve 28 is
If the engine stops (e.g. ignition switch
OFF signal), when the outside temperature is above the set temperature and the clutch is OFF (for example, when the clutch pedal is not depressed), it is controlled to open for a certain period of time. When the solenoid valve 28 opens, fuel in the first diaphragm chamber 12 or in another fuel system (downstream of the fuel pump 2) pushes down the diaphragm 23 and valve 24 against the second compression spring 26, and flows out from the passage 21. The fuel is returned to the fuel tank 1 via the return pipe 18.
When the fuel pressure becomes lower than the set pressure determined by the second compression spring 26, the second compression spring 26 pushes up the diaphragm 23 and the valve 24, and the passage opening 22
closes. In this way, the fuel pressure is controlled to the set pressure determined by the second compression spring 26.

If the fuel pressure in the fuel system is lowered in this way, fuel vapor will increase somewhat, but since the fuel pressure downstream of the fuel pump is low when the fuel pump starts rotating when the engine starts, it will take a while until the fuel pressure reaches a predetermined level. The discharge capacity of the fuel pump is improved (the margin of discharge capacity is increased), and vapor can be easily scavenged. In addition,
Until the fuel pressure reaches a certain level, the fuel pressure discharged from the fuel injector decreases, which may make it difficult to start the engine. When the battery voltage is above the set voltage and the clutch is ON (when the clutch pedal is depressed), the fuel pump 2 is driven for several seconds. Of course, the solenoid valve 28 is closed at this time.
As a result, the fuel pressure rises to a predetermined level under normal operating conditions, and excess fuel returns to the fuel tank 1 through the return pipe 18. Therefore, the engine startability and restartability can be improved.

However, by appropriately selecting the second compression spring 26, the set pressure determined by the second compression spring 26 can be set higher than the atmospheric pressure and can be adjusted to the fuel pressure (fuel discharge pressure) determined by the first compression spring 16. ), it is possible to set the most appropriate pressure within a smaller range, so the original purpose of improving the pump's discharge capacity at restart is sufficiently maintained, and the fuel pressure rises slowly at restart. This can be done to the extent that it does not occur.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a first embodiment of the fuel pressure control device of the present invention. 1...Fuel tank, 2...Fuel pump, 3...
Fuel pressure control device (pressure regulator), 1
2, 20... diaphragm chamber, 13, 23... diaphragm, 16, 26... spring, 18... return pipe, 19... opening, 21, 21'... passage, 28... opening/closing valve (electromagnetic valve).

Claims (1)

[Scope of utility model registration request] Fuel supplied from the fuel pump 2 of the fuel injection internal combustion engine is introduced into the diaphragm chamber 12 on the other side of the first diaphragm 13 to which the negative pressure of the intake pipe and the pressure of the first spring 16 are applied, and the fuel is In a fuel pressure control device that controls the pressure of fuel injected from a fuel injection device by displacing a diaphragm and opening the first opening 19 of the fuel return pipe 18 to return fuel to the fuel tank 1, the fuel return pipe 18 A passage 21 branching from the diaphragm chamber 12 is opened by a second opening 22 through an on-off valve 28, and the second opening 22 faces one surface of the second diaphragm 23 on which the fuel pressure of the diaphragm chamber 12 acts. and apply the pressure of the second spring 26 to the other surface of the second diaphragm so that the set pressure when the second opening 22 opens is smaller than the set pressure when the first opening 19 opens. A fuel pressure control device characterized in that springs 16 and 26 are set so that the on-off valve 28 is opened when the internal combustion engine is stopped.