JPH025087Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a fuel cutoff device for a multi-cylinder internal combustion engine that cuts off fuel supply to a specific cylinder during low load operation.

When a multi-cylinder internal combustion engine is idling or operating at a similar low load, the amount of fuel injection required for operation is narrowed down to a very small amount in each cylinder, which reduces combustion efficiency and worsens fuel efficiency.
There is a problem that the amount of hydrocarbons in the exhaust gas becomes high.

Conventionally, as a countermeasure, when a multi-cylinder internal combustion engine is operated at low load, the fuel supply to a specific cylinder is cut off, thereby increasing the load on the active cylinder and increasing the combustion efficiency of the active cylinder. In order to improve fuel efficiency, many fuel cutoff devices have been devised, such as one in which a solenoid valve is used to stop low-pressure fuel flowing into the main body of a fuel injection pump on the side of a specific cylinder whose fuel supply is cut off.

However, in the case of the above fuel cutoff method, since the volume inside the gear rally is large, there is a time delay when the fuel supply is cut off and when the fuel supply is restarted, which not only worsens the driving feeling but also causes problems such as oil dilution. , there was a possibility that the durability of the fuel injection nozzle would be adversely affected.

Further, Japanese Utility Model Publication No. 49-42490 discloses a system in which fuel is intermittently supplied to a specific cylinder using a solenoid valve provided in a discharge passage of a fuel injection pump.

However, in this publication, a solenoid valve is used to open and close a ball valve provided in a branch passage connected to the discharge passage of the injection pump, which requires a large solenoid valve capacity to directly open and close the high-pressure discharge passage. However, the spool valve device, which utilizes the fuel pressure of the fuel feed pump, had the disadvantage of not being able to shut off the fuel.

Therefore, the present invention was devised in order to eliminate the drawbacks of the conventional fuel cutoff device described above, and it cuts off the fuel in the high pressure injection path using a spool valve device that utilizes the fuel pressure of the fuel feed pump. The object of the present invention is to provide a fuel cutoff device for an internal combustion engine that can ensure high responsiveness when shutting down and restarting operation.

The present invention achieves the above-mentioned object by introducing high-pressure fuel into a high-pressure injection path connecting a fuel injection pump and a fuel injection nozzle of the specific cylinder, in order to cut off the fuel supply to a specific cylinder when the load is below a set load of a multi-cylinder internal combustion engine. A bypass passage that communicates with the leak passage and a spool valve device that opens and closes the bypass passage are provided, a directional switching valve that communicates the high pressure fuel leak passage with either the discharge side of the fuel feed pump or the fuel tank is provided, and the switching valve By switching, the spool valve device is moved to a position where the bypass passage is closed by the internal pressure of the fuel tank when the load is above the set load, and an open position where the bypass passage is opened by the fuel pressure from the fuel injection feed pump when the load is below the set load.

An embodiment of the present invention will be described below with reference to the drawings. FIGS. 1, 2, and 3 are schematic configuration diagrams of a fuel cutoff device for a multi-cylinder internal combustion engine in this embodiment. FIG. 1 shows the state when fuel is injected to all cylinders, and FIG. 2 shows the state when fuel supply to a specific cylinder is cut off.

First, 1 in the figure is a fuel injection pump, 2A,
2B, 2C, 2D are each fuel injection nozzle 3A, 3
These are high-pressure injection pipes that constitute high-pressure injection paths that supply high-pressure fuel to B, 3C, and 3D, respectively.

Next, in order to cut off the fuel supply to the fuel injection nozzles 3B and 3D of a specific cylinder when the internal combustion engine is operated at a load lower than the set load, the fuel injection nozzles 3
High pressure injection pipes 2B and 2D corresponding to B and 3D include
Bypass passage 5 communicating with high pressure fuel leak passage 4
A fuel cutoff valve main body 6 having numbers B and 5D is interposed.

Also, the pistons 7B and 7D that can block or connect the bypass passages 5B and 5C are connected to the rod 8.
A spool valve device 8 connected by B is slidably provided in the fuel cutoff valve body 6, and a spring 9 for pressing the spool valve device 8 is provided at the right end of the spool valve device 8, and a spring 9 is provided at the left end of the spool valve device 8 to press the spool valve device 8. A piston 7A is provided, one side of which faces the communication path to the high-pressure fuel leak path 4, and which is connected to the piston 7B via a rod 8B.

Next, reference numeral 10 indicates a fuel tank, and the fuel from the fuel tank 10 is fed to a fuel feed pump 11.
The fuel is supplied to the fuel injection pump 1 via the fuel filter 12 at the discharge side of the fuel feed pump 11,
A three-way solenoid valve 14 is disposed between the high-pressure fuel leak path 4 and the fuel return path 13 to the fuel tank 10, which allows communication between the pump 11 and the leak path 4 and between the leak path 4 and the tank 10. has been established,
When the switch 17 is open when the load is above the set load, the communication between the pump 11 and the leak path 4 is cut off, and the leak path 4 and the tank 10 are connected, and when the load is below the set load, the switch 17 is closed. Leak path 4 and tank 10
The pump 11 and the leak path 4 are communicated with each other.

Therefore, to explain the function of the fuel cutoff device with the above configuration, as shown in Fig. 1, during normal operation of this internal combustion engine (when the load is higher than the set load), 3.
The solenoid valve 14 communicates the high pressure fuel leak path 4 with the fuel return path 13, and the pressure applied to the left end of the piston 7A of the spool valve device 8 is transferred to the fuel tank 10.
, the spool valve device 8 is pushed to the left by the pressing force of the spring 9, the bypass passages 5B and 5D are cut off, and normal fuel injection is performed from all fuel injection nozzles 3A, 3B, 3C, and 3D. It is done.

Next, the fuel injection nozzles 3B, 3D of the specific cylinder
During so-called partial cylinder operation (when the load is less than the set load), the switch 17 closes and energizes the three-way solenoid valve 14, thereby shutting down the fuel feed pump 11. The discharge side and the high-pressure fuel leak passage 4 communicate with each other, and the fuel pressure of approximately 2 kg/cm ² from the fuel feed pump 11 acts on the piston 7A of the spool valve device 8, causing the spool valve device 8 to move against the spring 9. move it to the right,
Since the bypass passages 5B and 5D are connected, the high-pressure injection pipes 2B and 2D communicate with the high-pressure fuel leak passage 4, and the fuel to be pumped to the fuel injection nozzles 3B and 3D escapes from the high-pressure fuel leak passage 4 to the fuel filter side. Therefore, fuel injection from fuel injection nozzles B and 3D is cut off, allowing partial cylinder operation.

In addition, in the fuel cutoff valve main body 6 in the figure, 15
1 is a stopper of the spool valve device 8, and a hole 16 is connected to the fuel return path 13 side.

As explained above, the present invention provides a high-pressure injection path that connects a fuel injection pump and a fuel injection nozzle of the specific cylinder to cut off fuel supply to a specific cylinder when the load is below the set load of a multi-cylinder internal combustion engine. By providing a bypass passage that communicates with the high-pressure fuel leak passage and a spool valve device that opens and closes the bypass passage, and providing a directional switching valve that communicates the high-pressure fuel leak passage with either the discharge side of the fuel feed pump or the fuel tank, By switching this directional control valve, the spool valve device is moved to the closed position of the bypass passage by the internal pressure of the fuel tank when the load is above the set load, and to the open position of the bypass passage by the fuel pressure from the fuel injection feed pump when the load is below the set load. Therefore, the fuel can be cut off to a specific cylinder by switching the directional control valve, and the spool valve device operated by the fuel pressure of the fuel feed pump can be used, and the reliability can be ensured.

Moreover, since the structure is such that the bypass passage is opened and closed by a spool valve device, multiple bypass passages can be opened and closed simultaneously by the spool valve device.
This spool valve device is installed in the middle of the high-pressure injection pipe from the fuel injection pump to the fuel injection nozzle, so it eliminates time delays when shutting off fuel to the fuel cut cylinder and when restarting operation, increasing the fuel cut. You can get responsiveness.

[Brief explanation of the drawing]

1, 2, and 3 are schematic configuration diagrams of a fuel cutoff device for a multi-cylinder internal combustion engine according to an embodiment of the present invention. The figure shows a state in which fuel supply to a specific cylinder is cut off. Further, FIG. 3 is a sectional view taken along the line AA in FIG. 1. 1...Fuel injection pump, 2A, 2B, 2C, 2
D...High pressure injection pipe, 3A, 3B, 3C, 3D...
Fuel injection nozzle, 4...High pressure fuel leak path, 5
B, 5D...Bypass passage, 6...Fuel cutoff valve body, 8...Spool valve device, 11...Fuel feed pump, 14...3-way solenoid valve.

Claims (1)

[Scope of utility model registration request] In order to cut off fuel supply to a specific cylinder when the load is below a set load of a multi-cylinder internal combustion engine, a bypass passage communicating with a high pressure fuel leak path and the bypass are provided in a high pressure injection path connecting a fuel injection pump and a fuel injection nozzle of the specific cylinder. A spool valve device is provided to open and close the passage, and a directional switching valve is provided to communicate the high-pressure fuel leak path with either the discharge side of the fuel feed pump or the fuel tank, and by switching the switching valve, the spool valve device can be adjusted to the set load. As described above, there is provided a fuel cutoff device for a multi-cylinder internal combustion engine in which the bypass passage is moved to the closed position by the internal pressure of the fuel tank and the bypass passage is moved to the open position by the fuel pressure from the fuel injection feed pump when the load is below a set load.