JPS6026207Y2 - Fuel cut mechanism of fuel supply device for fuel injection pump - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a fuel cut mechanism for a fuel supply device for an injection pump of an internal combustion engine, particularly a diesel engine.

Conventionally, the fuel supply system of a fuel injection pump for a diesel engine is equipped with a fuel cut mechanism that cuts off the fuel supply to the pump.When stopping the engine, this mechanism quickly stops the engine. That's what I do.

As an example of this fuel cut mechanism, basically the
A configuration as shown in FIG. 1 based on the technical concept of Japanese Patent No. 17186 is used in an in-line fuel injection pump.

According to this configuration, an engine starting switch (for example, a key switch) 2 and a battery 3 are connected in series to a solenoid 1a of a fuel cut valve 1 consisting of a 4-point, 2-position electromagnetic switching valve, while each of the valves is Ports A, B, C, and D have a pipe 5 leading to the fuel tank 4, a pipe 7 connected to a fuel injection pump 6 that works with an engine (not shown), and a suction side of a feed pump 8 that works with the injection pump 6. and a pipe 13 whose inlet side is connected to the discharge side of the feed pump 8 via a pipe 11 having a check valve 10 in the middle, and to the outlet side of a filter 12, respectively. When the switch 2 is turned on, the fuel cut valve 1 is in the 1 position in the figure, and fuel from the fuel tank 4 is sucked into the feed pump 8 via the fuel cut valve 1, and is passed from the discharge side of the feed pump 8 to the filter 12. The engine starts by being supplied to the oil reservoir chamber (not shown) in the injection pump 6 through the fuel cut valve 1. On the other hand, when the switch 2 is turned off, the fuel cut valve 1 moves from the 1 position in the figure. The fuel in the oil reservoir of the injection pump 6 is sucked back by the feed pump 8 via the fuel cut valve 1, and this sucked back fuel passes through the filter 12 by the action of the pump 8, and then the fuel is cut off. By returning the fuel to the fuel link 4 via the valve 1, the fuel pressure in the fuel injection pump oil reservoir chamber is rapidly reduced, and the engine is stopped in a short time after the switch 2 is turned off.

However, in the conventional fuel cut mechanism that sucks fuel back from the fuel injection pump as described above, when the engine is stopped during high-speed rotation, the feed pump 8 is also rotating at high speed immediately after the switch 2 is turned off, so the injection The fuel in the pump 6 is suddenly sucked into the feed pump 8, and as a result, a large amount of the fuel filling the filter 12 returns to the fuel tank 4. Therefore, when starting the engine thereafter, switch 2 must be turned off. Immediately after the switch 2 is turned on, time is required to fill the large volume filter 12 with fuel, and during this time, fuel is not supplied to the injection pump 6, so the time from when the switch 2 is turned on until the engine starts becomes longer. It has the disadvantage of being stored away.

This disadvantage occurs because the pressure inside the fuel tank 4 is lower than the pressure inside the filter 12, so that the internal combustion in the filter 12 returns to the fuel tank 4.

Therefore, the present invention was devised to eliminate the drawbacks of the fuel cut t = structure of the conventional fuel supply device as described above.
A fuel bypass passage is provided in parallel with the filter, and in conjunction with an engine start switch, the fuel discharged from the feed pump is selectively supplied via the filter when the switch is on and via the fuel bypass passage when the switch is off. The present invention provides a fuel cut mechanism characterized in that a switching valve is provided in a fuel passage between the discharge side of the feed pump and the inlet side of the filter.

An embodiment of the present invention will be described below with reference to FIG.

FIG. 2 is a schematic diagram of the fuel cut H structure of the fuel supply system according to the present invention, and the same parts as in FIG. 1 are designated by the same reference numerals.

In the figure, reference numeral 14 is a fuel bypass passage provided in parallel with the filter 12, and a check valve 15 is provided in the middle of the fuel bypass passage 14 so that the flow can flow from the inlet side to the outlet side of the filter 12. It is.

A switching valve 16 is provided in the piping 11 between the discharge side of the feed pump 8 and the inlet side of the filter 12.
Reference numeral 6 is connected to the solenoid valve, and one end of a solenoid (not shown) is connected to the switch 2, and the other end is connected to the solenoid 1a of the fuel cut valve 1, so that the switching operation is performed in conjunction with the on/off of the switch 2. The feed pump 8 is connected to the filter 12 side through the pipe 11 when the switch 2 is on, and to the fuel bypass passage 14 side when the switch 2 is off, so that the fuel discharged from the feed pump 8 is selectively supplied.

Therefore, when the engine is running, that is, when the switch 2 is on, the fuel cut valve 1 is in the 1 position, and the fuel in the fuel tank 4 is transferred to the pipe 5, the fuel cut valve 1, the pipe 9, the feed pump 8,
Piping 11. The oil is supplied to the oil reservoir chamber of the injection pump 6 through the check valve 10, the switching valve 16, the filter 12, the pipe 13, the fuel cut valve 1 and the pipe 7, and normal engine operation is performed (in this state, the oil inside the filter 12 is is full of fuel).

Immediately after the switch 2 is turned off during engine operation, the fuel cut valve 1 is switched from the 1 position to the ■ position, and at the same time the switching valve 16 is switched to the position where the pipe 11 is communicated with the bypass passage 14, and the fuel cut valve 1 is switched from the 1 position to the ■ position. Fuel sucked into the feed pump 8 from the oil reservoir chamber of the injection pump 6 through the piping 7, the fuel cut valve 1, and the piping 9 flows from the discharge side of the feed pump 8 through the switching valve 16 into the fuel bypass passage 14 side. Return to fuel tank 4.

In this way, the fuel sent from the feed pump 8 does not flow into the inlet side of the filter, so the filter 12 is able to resist the effects of the sudden return of fuel from the feed pump 8 to the fuel tank 4 due to the switch 2 being turned off. Therefore, even if the switch 2 is turned off when the engine is running at high speed, the return of fuel from the filter 12 to the fuel tank 4 is extremely rare, and a state in which the inside of the filter 12 is filled with fuel is ensured.

Note that when the switch 2 is turned off and the switching valve 16 is in a position where the pipe 11 communicates with the pipe 14, the upstream side of the pipe 11 and the inlet side of the filter 12 are completely cut off, so that the filter 12 The amount of fuel leaking from the fuel tank 4 to the fuel tank 4 is extremely small, ensuring that the filter 12 is filled with fuel.

Therefore, when the engine is subsequently started, when the switch 2 is turned on and the fuel cut valve 1 is switched to the 1 position, since the filter 12 is filled with fuel, the rotation of the feed pump 8 causes the fuel in the fuel tank 4 to be filled. When fuel is sucked into the feed pump 8, fuel is supplied into the injection pump 6 from the outlet side of the filter almost at the same time, and the engine starts in an extremely short time after the switch 2 is turned on.

According to the fuel injection pump equipped with the fuel cut mechanism of the present invention having the above-described configuration, as shown in FIG. The time can be reduced to about half compared to the conventional one shown in FIG.

As explained above, according to the present invention, a fuel bypass passage is provided in parallel with the filter, and a switching valve is provided for switching the connection between the feed pump, the bypass passage, and the filter, so that the fuel is discharged from the feed pump when the engine is started. Since the fuel is bypassed and returned to the fuel tank without passing through the large-capacity filter, the filter can be filled with fuel even when the engine is stopped, and therefore the starting time, that is, the engine start switch ( For example, the time it takes for the engine to start after turning on the key switch (for example, the key switch) can be significantly shortened.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of a fuel cut mechanism of a conventional fuel supply device, Fig. 2 is a schematic diagram of a fuel cut mechanism of a fuel supply device according to the present invention, and Fig. 3 is a schematic diagram of a fuel cut mechanism of a conventional fuel supply device. A graph showing the starting characteristics of the injection pump, and a fourth
The figure is a graph similar to FIG. 3 based on the fuel cut mechanism according to the present invention. 1...Fuel cut valve, 2...Engine start switch, 4...Fuel tank, 6...
... Injection pump, 8 ... Feed pump, 12
... Filter, 14 ... Fuel bypass passage, 16 ... Switching valve.

Claims (1)

[Scope of utility model registration request] When the engine is running, fuel is supplied from the fuel tank to the fuel injection pump via the feed pump and filter by the on/off operation of the engine start switch and the switching operation of the moving fuel cut valve, while when the engine is stopped, fuel is supplied from the fuel tank to the fuel injection pump via the feed pump and filter In a fuel cut mechanism of a fuel supply device for a fuel injection pump configured to return fuel from a fuel injection pump to a fuel tank via a feed pump and a filter, a fuel bypass passage is provided in parallel with the filter, and a fuel bypass passage is provided in parallel with the discharge side of the feed pump. A switching valve that is linked to the on/off operation of the engine start switch is provided in the fuel passage between the inlet sides of the filter, and the discharge side of the foot pump is connected to the fuel passage.
The fuel cut mechanism is characterized in that the switching valve is operated to communicate with the inlet side of the filter when the engine is running, and with the fuel bypass passage when the engine is stopped.