JPS6133253Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an abnormal noise prevention device for a fuel piping system in an internal combustion engine.

As shown in Fig. 1, the fuel piping in a diesel engine is connected between a fuel tank 1 and a fuel injection pump 2 by a feed pipe 3 and a return pipe 4. and filter 6
is provided. In this case, in the feed pipe 3, during the reciprocating motion when the feed pump 5 sucks up fuel, pressure fluctuations due to the closing of the check valve cause pulsations in the fuel flowing through the feed pipe 3, which causes an abnormality called the so-called water hammer phenomenon. There were times when noise was generated.

This invention solves this problem, and its feature is that a pressure damping mechanism is installed in the check valve, which is the on-off valve installed in the feed pipe, to suppress the generation of high pressure, which is the cause of abnormal noise. .

Embodiments of the present invention will be described below with reference to FIGS. 2 and 3. 3 indicates a feed pump, 7 is a discharge side, and 8 is a suction side. In the case of the feed pump 5 shown in this figure, the check valves provided on the discharge side 7 and the suction side 8 are of the double action type, but may be of the single action type. That is, 9 is a valve element on the discharge side 7, and 10 is a valve element on the suction side 8, which are pressed in the closing direction by a spring and are alternately and relatively opened and closed by the reciprocating operation of a plunger 11, which will be described later.

A plunger 11 that reciprocates is provided between the valve bodies 9 and 10. 12 is a spring for pushing up the plunger 11, and 13 is a cam for pushing down the plunger 11, which is driven in conjunction with the rotation of the engine.

In the present invention, a pressure damping mechanism is provided in one or both of the valve bodies 9 and 10 on the discharge side 7 and suction side 8 in the above structure. In the illustrated example, it is provided on the valve body 9 on the discharge side 7, and its specific structure is, as shown in FIG. A shaft 15 is integrally formed in a protruding manner and is fixed to the casing of the feed pump 5. The shaft 15 fits into the cylindrical body 14 with a gap 16 when the valve body 9 is closed.

Since the present invention has the above-mentioned structure, fuel is pumped from the fuel tank 1 to the fuel injection pump 2 by reciprocating the plunger 11 by the rotation of the cam 13 based on the rotation of the engine. The valve bodies 9 on the suction side 8 are alternately opened and closed, and the valve body 10 on the suction side 8 is alternately opened and closed relative to the valve body 9 on the discharge side 7 to suck up and pressure feed the fuel from the fuel tank 1.

When the pressure of the fuel flowing in the feed pipe 3 increases, which is a cause of noise generation during this pressure feeding, the shaft 15 fits into the cylinder body 14 when the valve body 9 is closed, and the small hole 14a and the gap 16 This causes a throttling action and the valve body 9 is gradually closed, so the increased pressure passes through the part of the valve body 9 that is to be closed and flows to the suction side 8, resulting in high-pressure dipping. . Therefore, when the valve body 9 is completely closed, the water hammer phenomenon due to the back pressure of the high-pressure fluid, which causes abnormal noise, is avoided.

According to the present invention, a cylindrical body with a small hole is provided protruding from the valve surface of the valve body of a conventionally known feed pump, and a shaft that fits into the cylindrical body with a gap is fixed to the pump casing side. By providing a pressure damping mechanism with a simple structure, the pulsating pressure in the fuel piping system can be controlled and abnormal noise can be reliably prevented. Further, this pressure damping mechanism has the advantage that it can be added to the basic configuration of a conventionally known feed pump without significantly changing or deforming the design.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of the fuel piping system, FIG. 2 is a sectional view of the device of the present invention, and FIG. 3 is a partial sectional view of the main parts. 1...Fuel tank, 2...Fuel injection pump, 3
...Feed pipe, 5...Feed pump, 7
...Discharge side, 8...Suction side, 9, 10...Valve body,
11... Plunger, 14... Cylindrical body, 14a...
Small hole, 15... axis, 16... gap.

Claims (1)

[Scope of utility model registration request] A plunger that is reciprocated by a cam and a spring is installed in the center of the feed pipe that connects the fuel tank and the fuel injection pump. In a feed pump equipped with a valve body that opens and closes at the same time, a cylindrical body with a small hole is provided protruding from the valve surface of the valve body of the feed pump, and a shaft that fits into the cylindrical body with a gap is connected to the pump. A fuel piping system noise prevention device that includes a pressure damping mechanism fixed to the casing side.