JPH10131770A - Distributor type fuel injection pump having load sensing timer for diesel engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent occurrence of abrupt reduction of a torque even when operation of an accelerator pedal is abruptly stopped in a diesel engine provided with a load sensing timer. SOLUTION: A ring valve 9 which can block an orifice 9 is arranged on a governor sleeve 6 so as to be slidable from a non-blocking position to a blocking position of the orifice 9 by expansion of a second centrifugal flyweight 12 which is operated only under high speed rotation, when at least first centrifugal flyweight 11 is expanded. The ring valve 7 energizes the second flyweight 12 by means of a spring 14 so as not to expand it.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diesel engine, and more particularly to an improvement of a distribution type fuel injection pump with a load sensing timer for controlling a timer advance amount in accordance with an engine load.

[0002]

2. Description of the Related Art In a distributed fuel injection pump used in a diesel engine, the pressure in a hydraulic chamber is controlled in accordance with the engine load, while the timer advance amount is reduced during running under light load to achieve quietness (diesel knock). It is indispensable to provide a load sensing timer that ensures the sound reduction) and increases the timer advance amount during high-load running to prevent a decrease in output and an increase in fuel consumption. FIG. 3 shows the load sensing timer arranged in the distribution type fuel injection pump. Since fuel is fed into the hydraulic chamber 2 by the feed pump 1 that is drivingly connected to the crankshaft, the fuel oil pressure in the hydraulic chamber 2 changes according to the engine speed. The load sensing timer protrudes the governor shaft 5 into the hydraulic chamber 2, mounts the governor sleeve 8 slid on the governor shaft 5 by the expansion operation of the centrifugal flyweight 15, and sets a high fuel pressure in the hydraulic chamber 2. Timer 3 adjusted so that the timer advance amount increases by
When the load becomes lighter than the high load (the injection amount is large), the governor sleeve 6 is pushed out by a fly weight, and the orifice 9 formed in the governor sleeve 6 and the return port 8 are matched with each other. The fuel pressure in the hydraulic chamber 2 is released to the suction side of the feed pump 1 through the fuel return passage 4, whereby the fuel oil pressure is reduced to reduce the timer advance angle. With such a configuration, when the engine load is reduced, the load sensing timer operates so as to reduce the timer advance amount regardless of the engine rotation speed. The torque is suddenly reduced, and the torque is reduced, the feeling is impaired, and the fuel consumption and the output performance tend to decrease.

[0003] Conventionally, in order to disable the function of lowering the fuel oil pressure when the engine is rotating at high speed, for example, as specifically illustrated in Japanese Patent Application Laid-Open No. Sho 57-163127, a fuel return passage is provided. There has been proposed a technique in which a cut valve that closes a fuel return passage when a fuel pressure in a room is high is provided.

[0004]

The prior art in which a cut valve is provided in a fuel return passage has a structure in which the cut valve is directly operated by the fuel oil pressure in a hydraulic chamber. To provide a flow path for introduction,
Since the cut valve must be incorporated, it becomes too complicated, which tends to cause malfunction and insufficient body strength. In addition, if the structure uses an electromagnetic valve that detects the number of revolutions of the engine and operates during high-speed rotation, malfunctions are likely to occur due to electrical trouble.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a distribution type fuel injection pump with a load sensing timer, which has a simple and effective configuration and can operate the load sensing timer only when the engine is running at a low speed. The structure is such that a governor sleeve having an orifice formed in the peripheral surface is fitted to a governor shaft protruding into the hydraulic chamber, and a fuel return port formed in the governor shaft by the expansion operation of the first centrifugal flyweight matches the orifice. A valve capable of closing the orifice is mounted on the governor sleeve so as to be slidable from a position not to be matched to the corresponding position, and is operated only when the first centrifugal flyweight is at least expanding at the time of high speed rotation. From the position where the orifice is not closed by the extension operation of the second centrifugal flyweight to the position where the orifice is closed Rotatably to wearing, further, the relative and governor sleeve and the valve, in that the assembly while applying a biasing force against the expansion operation of the first and second centrifugal flyweight. Preferably, the valve has a ring shape.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a distribution type fuel injection pump (hereinafter simply referred to as a fuel injection pump) with a load sensing timer for a diesel engine according to the present invention will be described with reference to the drawings. FIG. 1 shows a load sensing timer. Reference numeral 1 denotes a feed pump which is drivingly connected to a crankshaft (not shown) and feeds fuel into a hydraulic chamber 2 according to the rotation speed of an engine. The hydraulic chamber 2 is provided with a fuel return passage 4 connected to a suction side of the feed pump 1.
The distal end portion of the governor shaft 5 through which the hole extends is projected. A governor sleeve 6 is slidably mounted on the outer periphery of the governor shaft 5, and a ring-shaped valve (hereinafter referred to as a ring valve) 7 is further slidably mounted on the governor sleeve 6. At the tip of the governor shaft 5, a return port 8 is formed which communicates with the fuel return passage 4 from the side, while the governor sleeve 6 is provided with an orifice 9 which matches the return port 8 at a predetermined sliding position. Has been established. When the ring valve 7 is located on the outer periphery of the orifice 9, the orifice 9 is completely closed.

A fly weight case 10 is rotatably mounted on the governor shaft 5, and the fly weight case 10 is drivingly connected to a crankshaft. A first centrifugal flyweight 11 and a second centrifugal flyweight 12 are accommodated in the flyweight case 10 so as to be separated from each other in the axial direction. The orifice 9 is slidably mounted from a position not matching the return port 8 to a matching position.
The ring valve 7 is slidably mounted from a position where the orifice 9 is not closed to a position where the orifice 9 is closed by the expanding operation of the second centrifugal flyweight 12. Then, the distal end of the governor sleeve 6 is brought into contact with the control lever 13 and the ring valve 7 is pushed back to the proximal end by a spring 14 fixed at one end to the housing. It is assembled in a state in which an urging force against the expanding operation is applied. The first centrifugal flyweight 11 starts the expanding operation at a low speed rotation, and the second centrifugal flyweight does not operate unless it rotates at a high speed.

In the load sensing timer formed as described above, the feed pump 1 is operated by the rotation of the engine, the fuel is fed into the hydraulic chamber 2, and the fuel oil pressure corresponding to the rotation speed of the engine is generated in the hydraulic chamber 2. I do. When the engine is running at a low speed and running under a high load, the timer advance angle is set to a large value to prevent a decrease in output and an increase in fuel consumption. When the biasing force is released, the governor sleeve 6 is pushed by the first centrifugal flyweight 11 and advances until the orifice 9 and the return port 8 are aligned (FIG. 2A), whereby the hydraulic chamber 2 The fuel pressure escapes to the feed pump 1 side through the fuel return passage 4, whereby the fuel oil pressure decreases, the timer advance amount decreases, and quietness is ensured. Further, even during high-speed rotation and high-load running, the timer advance amount becomes large, and similarly to low-speed rotation, a decrease in output and an increase in fuel consumption are prevented.
When the high-speed running state changes from high-load running to low-load running, the governor sleeve 6 is pushed by the first centrifugal flyweight 11 by the release of the urging force by the control lever 13, and the orifice 9 and the return port 8 are connected. Move forward until it meets, but the second centrifugal flyweight 12
The ring valve 7 closes the orifice 9 by the operation (b in FIG. 2), the fuel pressure in the hydraulic chamber 2 does not escape to the feed pump side, the hydraulic pressure in the hydraulic chamber 2 does not change, and the timer The amount of advance does not change.

In the above embodiment, since a ring-shaped valve is used, it is easy to slidably assemble the governor sleeve by the operation of the centrifugal flyweight, and it operates accurately.

[0010] The means for urging the valve is not limited to the embodiment, and a well-known urging means can be adopted. The rotation range in which the second flyweight operates depends on the structure of the flyweight and the rotation of the urging means. High-speed rotation, for example, 250
Set to 0 rpm or more. In addition, the urging force against the expanding operation of the first flyweight is configured such that the distal end of the governor sleeve abuts on the control lever that operates according to the engine load and is applied through the governor sleeve. Preferably, the biasing force against the expanding operation of the second flywheel is not only applied through a valve, but also
It can be applied directly to the flywheel.

[0011]

According to the fuel injection pump of the present invention, on a highway or the like, the load sensing timer does not operate even if the foot is released from the accelerator when the vehicle is running under a high load. It can be implemented only by adding centrifugal fly weights and valves. Further, by forming the valve in a ring shape, the valve can be easily slidably attached to the governor sleeve by the operation of the centrifugal flyweight.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a load sensing timer of a fuel injection pump according to the present invention.

FIG. 2 is an explanatory diagram showing a positional relationship between a return port and an orifice that changes according to an expanding operation of first and second centrifugal flyweights.

FIG. 3 is an explanatory diagram of a conventional example.

[Explanation of symbols]

1. Feed pump, 2. Hydraulic chamber, 3. Timer,
4 Fuel return passage, 5 Governor shaft, 6
.. governor sleeve, 7. ring valve, 8. return port, 9. orifice, 10 fly weight case, 11. first centrifugal flight weight, 1
2nd second centrifugal flyweight, 13 control lever, 14 spring, 15 centrifugal flyweight.

Claims (2)

[Claims] 1. A governor shaft protruding into a hydraulic chamber,
A governor sleeve having an orifice formed in its peripheral surface is slidably mounted from a position where the fuel return port formed on the governor shaft and the orifice do not coincide with each other by the expanding operation of the first centrifugal flyweight. Also, the governor sleeve has a valve capable of closing the orifice, and at least the first centrifugal flyweight expands the orifice by an expanding operation of a second centrifugal flyweight that operates only at high speed rotation. It was slidably mounted from a position not to be closed to a position to be closed, and further assembled to the governor sleeve and the valve while applying a biasing force against the expanding operation of the first and second centrifugal flyweights. Distribution type fuel injection pump with load sensing timer for diesel engine. 2. The distribution type fuel injection pump according to claim 1, wherein the valve has a ring shape.