JPS6026210Y2 - 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 fuel injection pumps for diesel engines has been 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. 2-17186 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 A filter 6 connected to the fuel tank 5 via piping 4 is connected to ports A, B, C, and D.
a pipe 7 connected to a fuel injection pump 8 linked to an engine (not shown), a pipe 9 connected to the suction side of a feed pump 10 linked to the injection pump 8
1, and the arrangement '1' which is connected to the feed pump 10 and has a check valve 12 interposed therebetween which allows the flow of fuel toward the fuel cut valve.
t13 are respectively connected, and when the switch 2 is on, the fuel cut valve 1 is in the position ■ in the figure, and fuel from the fuel tank 5 is sucked into the feed pump 10 via the filter 6 and the fuel cut valve 1, and the feed pump The engine is started by supplying oil from the discharge side of fuel cut valve 1 to an oil reservoir (not shown) in injection pump 8 through fuel cut valve 1. On the other hand, when switch 2 is turned off, fuel cut valve 1 moves from position ■ in the figure. (3) position, the fuel is sucked back by the feed pump 10 through the fuel cut valve 1 in the oil reservoir chamber of the injection pump 8, and this sucked back fuel is transferred to the fuel cut valve 1 and the filter 6 by the action of the pump 10. By returning the fuel to the tank 5, the fuel pressure in the oil reservoir of the fuel injection pump 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 10 is rotating at high speed immediately after switch 2 is turned off, so injection is not performed. The fuel in the pump 8 is rapidly sucked into the feed pump 10, and as a result, a large amount of the fuel filling the filter 6 returns to the fuel tank 5. 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 6 with fuel, and during this time, fuel is not supplied to the injection pump 8, 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 arises because the flow of fuel generated by the sudden return phenomenon of fuel acts on the filter 6 and returns a large amount of the fuel filling the filter 6 to the fuel tank 5.

Therefore, the present invention was devised to eliminate the drawbacks of the conventional fuel supply device and fuel cut mechanism as described above.
A fuel bypass passage that bypasses the filter and leads to the fuel tank is connected to the pipe on the injection pump side of the filter, and the fuel can flow in the fuel supply direction from the connection point between the pipe and the bypass passage to the pipe that leads to the fuel tank via the filter. In addition to disposing a second check valve, a third check valve that can flow in the fuel return direction is disposed in the fuel bypass passage, and when the engine is stopped, the fuel sucked from the injection pump is passed through the bypass passage. The present invention provides a fuel cut mechanism that prevents a large amount of fuel from being returned to the fuel tank from the filter due to the flow of fuel.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.

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

A bypass passage 14 that communicates with the fuel tank 5 is connected to the pipe 7 that connects the fuel cut valve 1 and the filter 6 in parallel with the filter 6 .

Connection point 15 between piping 7 and bypass passage 14 and filter 6
A second check valve 16 is disposed between the fuel cut valve 1 and the fuel supply direction, while the fuel bypass passage 14 is provided with a second check valve 16 that allows the flow of the fuel toward the fuel tank 5, that is, the fuel return direction. A third check valve 17 that allows flow in the direction is provided.

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 5 is transferred to the pipe 4.
, filter 6, check valve 16, piping 7, fuel cut valve 1,
Piping 11, feed pump 10, check valve 12, piping 13
The fuel is supplied to the oil reservoir chamber of the injection pump through the fuel cut valve 1 and piping 9, and normal engine operation is performed (in this state, the filter 6 is filled with 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 the oil is passed from the oil reservoir chamber of the fuel injection pump 8 to the pipe 9, the fuel cut valve 1, and the pipe 11. The fuel sucked into the feed pump 10 flows into the pipe 7 from the discharge side of the feed pump 10 via the check valve 12, the pipe 13, and the fuel cut valve 1.

Since the second check valve 16 prevents the fuel from flowing toward the returned fuel filter 6, the fuel that has flowed into the pipe 7 passes through the third check valve 17 and the bypass passage 14 to the fuel tank 5. will be returned to.

In this way, the fuel sent from the feed pump 10 does not flow into the filter 6, so the filter 6 is connected to the switch 2.
is no longer affected by the sudden return of fuel from the feed pump 10 to the fuel tank 5 due to the switch being turned off, and therefore, even if the switch 2 is turned off when the engine is running at high speed, fuel will not return from the filter 6 to the fuel tank 5. is extremely small, and a state in which the inside of the filter 6 is filled with fuel is ensured.

Therefore, when the engine is subsequently started, when the switch 2 is turned on and the fuel cut valve 1 is switched to the position ■, the filter 6 is filled with fuel, so the rotation of the feed pump 10 causes the fuel in the fuel tank 5 to be filled. When fuel is sucked into the feed pump 10, fuel is supplied from the filter 6 into the injection pump 8 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.

Further, in the above embodiment, the second check valve 16 is disposed between the connection point 15 between the pipe 11 and the bypass passage 14 and the filter 6, so that the fuel is returned without going through the filter 6 itself. However, instead of this second check valve 16, a second check valve is installed between the filter 6 and the fuel tank 5, as shown in FIG.
A check valve 16' may also be provided.

As explained above, according to the present invention, a fuel bypass passage that bypasses the filter and leads to the fuel tank is connected to the pipe connecting the fuel cut valve and the filter, and fuel is supplied to the pipe that leads to the fuel tank via the filter. A check valve that can flow in the fuel return direction is provided, and a check valve that can flow in the fuel return direction is provided in the fuel bypass passage, so that the fuel sucked from the injection pump when the engine is stopped is passed through the bypass passage. Since the filter is bypassed and returned to the fuel tank, a large amount of fuel is not returned from the filter to the fuel tank due to the flow of returning fuel, and the filter is kept full of fuel even when the engine is stopped. and therefore the starting time, i.e. 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.

It also has the advantage of being extremely simple in structure.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of a fuel cut mechanism of a conventional fuel supply device, FIG. 2 is a schematic configuration diagram showing an embodiment of the fuel cut mechanism according to the present invention, and FIG. 3 is a diagram of a conventional fuel cut mechanism. A graph showing the starting characteristics of a fuel injection pump, FIG. 4 is a graph similar to FIG. 3 based on the fuel cut mechanism according to the present invention, and FIG. 5 is a schematic configuration diagram showing another embodiment according to the present invention. be. 1...Fuel cut valve, 2...Engine start switch, 5...Fuel tank, 6...
...Filter, 8...Injection pump, 10...
...Feed pump, 14...Fuel bypass passage, 16...Second check valve, 17...
Third check valve.

Claims (1)

[Scope of Claim for Utility Model Registration] 1. Fuel is supplied from the fuel tank to the fuel injection pump via the filter and feed pump during engine operation by switching the fuel cut valve in conjunction with the on/off operation of the engine start switch. , in a fuel cut mechanism of a fuel supply device for a fuel injection pump configured to return fuel from the fuel injection pump to a fuel tank by a feed pump when the engine is stopped, the filter is bypassed to the piping on the injection pump side of the filter. A first check valve that connects a fuel bypass passage leading to a fuel tank and is capable of flowing in a fuel supply direction from a connection point between the piping and the bypass passage to a piping that leads to the fuel tank via a filter; A second check valve that can flow in the fuel return direction is disposed in the fuel bypass passage, so that when the engine is stopped, the fuel is returned to the fuel tank via the fuel bypass passage. Fuel cut mechanism of fuel supply device for fuel injection pump. 2. The fuel cut mechanism for a fuel supply device for a fuel injection pump according to claim 1, wherein the first check valve is provided between the connection point and the filter. 3. Utility model registration claim 1, characterized in that the first check valve is provided between the filter and the fuel tank.
A fuel cut mechanism of a fuel supply device for a fuel injection pump as described in 2.