JPS6210466Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an overflow valve for a fuel injection pump in an internal combustion engine.

The purpose of this invention is to prevent overflow fuel from being sucked into the fuel chamber on the side that is cut off when the fuel supply is cut off, in a fuel injection pump that has a function to cut off fuel supply to some cylinders, and to operate with a reduced number of cylinders. The objective is to improve the effectiveness of the exhaust gas and improve exhaust odor.

BACKGROUND ART Conventionally, fuel injection pumps have been known that have a function of cutting off fuel supply to some cylinders during idling or load change to cause reduced cylinder operation. Its structure will be explained with reference to FIG. 1. Reference numeral 1 denotes a fuel injection pump body, which has a plurality of pump plunger barrels 2a and 2b corresponding to the number of cylinders of an internal combustion engine (not shown). The plurality of barrels 2a, 2b are divided by fuel chambers A, B, which divide the inside of the fuel injection pump main body 1 into two chambers. A fuel supply pipe 3 from a fuel filter (not shown) is communicated with the fuel chambers A and B through branch pipes 3a and 3b, and it is necessary to supply fuel to the fuel chamber B side between the branch pipes 3a and 3b. A fuel cut valve 4 is installed to shut off the fuel by shutting off the fuel.

In addition, overflow valves 6 are provided in the fuel chambers A and B.
a, 6b are attached, and the fuel overflowing from the fuel chambers A, B is merged into the overflow pipe 5 through the branch pipes 5a, 5b into a fuel tank (not shown).
It is starting to return to . The overflow valves 6a and 6b are connected to the fuel chamber A and
Fuel inlet 8 and branch pipes 5a, 5 communicating with B
a sleeve 7 having a fuel outlet 9 communicating with b;
A valve body 10 was provided inside the fuel inlet port 8 to open it when pushed by the pressure of overflow fuel and close it by the pressing force of a spring 11 that abuts a spring receiver 12 which also serves as a stopper. .

Such conventional overflow valves 6a, 6
In b, during cylinder reduction operation of the internal combustion engine with fuel supply to the fuel chamber B side cut off, the valve body 10 of the overflow valve 6b on the fuel chamber B side causes so-called valve movement due to the operation of the plunger on the barrel 2b side. The overflow fuel generated and flowing through the overflow pipe 5 from the fuel chamber A side where the injection operation is being performed is sucked into the fuel chamber B side, and as a result, the overflow fuel is sucked into the cylinder whose cylinders are being reduced. There was a problem that the effectiveness of cylinder operation was halved and exhaust odor was emitted.

The present invention provides an overflow valve that improves the above-mentioned conventional problems.The feature is that two sets of valve bodies are combined in series in two stages, and two seating sections are provided to prevent overflow fuel from being sucked. This is an extreme reduction.

An embodiment of the present invention will be described below with reference to FIG. 6a is fuel chamber B on the side where fuel supply is cut off
This is an overflow valve installed in the 7 is a sleeve forming a valve body, and has a fuel inlet 8 communicating with the fuel chamber B and an outlet 9 communicating with a branch pipe 5b connected to the overflow pipe 5;
A two-stage ball valve structure having the following structure is installed between the fuel inlet 8 and the fuel outlet 9 in the sleeve 7.

That is, a double nut 13 having a through hole 14 between the fuel inlet 8 and the fuel outlet 9 and a valve seat 15 having a through hole 16 corresponding to the through hole 14 are screwed together to be fixed in position. and,
A first valve body 10 is installed in the fuel inlet 8 and a second valve body 17 is installed in the through hole 16 of the valve seat 15 in series so that they can be opened and closed by moving in the same direction.
The valve body 10 is pressed in the closing direction by a first spring 11 interposed between it and a double nut 13, and the second valve body 17 is pressed in the closing direction by a spring receiver 12 screwed onto the end of the sleeve 7 and serving as a stopper. It has a structure in which it is pressed in the closing direction by a second spring 18 interposed between the two. In addition, in Figures 2 and 3,
Each valve body is depicted as a ball valve, but
It is not necessarily limited to this shape, but can also be cylindrical,
Of course, a ball valve body such as a disc-shaped valve body can also be used.

According to the overflow valve of the present invention having the above-mentioned structure, between the fuel inlet 8 and the fuel outlet 9 are the first valve body 10 and the first valve body 10 in two stages in series, which are pressed in the closing direction by springs 11 and 18, respectively. Since it has a double valve structure with two valve bodies 17,
When fuel supply to the fuel chamber B side is cut off by the fuel cut valve 4 and cylinder reduction operation is performed by the pump action of the fuel chamber A side, the plunger of the barrel 2b on the fuel chamber B side to which fuel is not supplied The first
Even if the second valve body 10 moves, the second valve body 17
is maintained in a closed state, so the overflow fuel flowing through the overflow pipe 5 is transferred to the fuel chamber B.
Prevent or extremely reduce suction into the body.
In addition, overflow fuel during all-cylinder operation is
The first valve body 10 and the second valve body 17 are pushed open to cause the fuel to flow from the outlet 9 to the overflow pipe 5 via the branch pipe 5b.

Therefore, the present invention eliminates the problem of sucking some of the overflow fuel into the cylinder whose cylinders are being reduced when the fuel supply is partially cut off, thereby improving the cylinder reduction effect and reducing the emission of white smoke from the exhaust. It has the advantage that it can be eliminated.

[Brief explanation of drawings]

FIG. 1 is a plan view of a fuel injection pump having a function of partially cutting off fuel supply, FIG. 2 is a sectional view of a conventional overflow valve, and FIG. 3 is a sectional view of an overflow valve according to the present invention. 1... Fuel injection pump, 2a, 2b... Barrel, 3... Fuel supply pipe, 4... Fuel cut valve, 5... Overflow pipe, 6a... Overflow valve, 7... Sleeve, 8... Fuel inlet , 9... fuel outlet, 10... first valve body,
DESCRIPTION OF SYMBOLS 11...First spring, 14...Valve seat, 16...Through hole, 17...Second valve body, 18...
...Second spring.

Claims (1)

[Scope of utility model registration request] A plurality of barrels are divided into two fuel chambers, a fuel cut valve is provided in the fuel supply path communicating with the fuel chamber to cut off the fuel supply to one chamber, and an overflow valve is installed in each of the two fuel chambers. In a fuel injection pump in which overflow fuel discharged from the overflow valve is combined with an overflow pipe and returned to the fuel tank, the overflow valve installed in the fuel chamber on the side where the fuel supply can be cut off is connected to the fuel inlet port. A valve seat is provided between the fuel inlet and the fuel outlet in a sleeve having a fuel inlet and an outlet, a first valve element for opening and closing the fuel inlet, and a valve seat disposed in the same direction as the first valve element. An overflow valve for a fuel injection pump, characterized in that it has a structure including a second valve element that moves to open and close an intermediate valve seat, and a spring that presses and biases each of these valve elements in a closing direction.