JPH10227270A - Fuel injection valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent dust and gas from entering a fuel injection valve by forming an accumulator chamber in a strainer piece in a fuel injection valve provided with a strainer in a fuel entry passage. SOLUTION: A fuel injection valve has an adapter 2 on the side of a fuel injection valve body 16 and a fuel pipe 22 to which high pressure oil is supplied from a fuel injection pump is joined to the adapter 2 by a female threaded pipe 19 and a strainer piece 1 is fitted in the adapter 2, a gap between the outer surface of the strainer piece 1 and the inner surface of the adapter 2 acting as a strainer. When high pressure filtered fuel oil is introduced into a nozzle chamber 11 via a high pressure fuel oil passage 8 to push up a nozzle needle 12, the fuel oil is injected from an injection port 27. The strainer piece 1 has an accumulator chamber (a) formed in a rectangular hole so as to keep pressure remaining in the high pressure fuel oil passage 8 high.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a strainer disposed inside an adapter mounted on a fuel injection valve body of a fuel injection valve and interposed in a fuel oil inlet passage.

[0002]

2. Description of the Related Art Conventionally, a technique relating to a structure of a strainer of a fuel injection valve has been known. For example, Japanese Utility Model Publication No. 56-17717 and Japanese Utility Model Publication No. 53-2
This is like the technique described in US Pat. In the fuel injection valve of a diesel engine, a device called a bar filter or an edge filter is installed at the inlet of the fuel injection valve in order to prevent the occurrence of injection failure due to the entry of foreign substances such as dust and dust in the fuel oil supply path. Many are provided on the side.

[0005] The prior art shown in FIG. 5 shows a configuration in which a strainer piece 31 serving only as a filter is provided inside an adapter 2. In this prior art, semicircular cuts 31a and 31b are provided at four locations at every 90 degrees on the outer periphery of the strainer piece 31. An entrance-side semicircular cut 31b is provided at a position facing 180 degrees, and an exit-side semicircle cut 31a is formed at a position facing 180 degrees between them. A slight gap is provided between the outer periphery of the strainer piece 31 and the inner periphery of the adapter 2, and the high-pressure fuel oil flows from the inlet-side semicircular cut 31b to the outlet-side semicircular cut 31a. The strainer piece 31 filters the fuel oil.

[0004] In the prior art shown in FIG.
The technology of the additional volume body 41 provided with 1b is disclosed. The additional volume body 41 is provided with a pressure accumulating chamber 41b, and has an oil passage hole 41c penetrating therethrough.
The strainer is not configured because the high-pressure fuel oil is configured to easily pass through 1c. A throttle hole 41a is formed in an oil passage hole 41c inside the additional volume body 41, and communicates between the oil passage hole 41c and the pressure accumulating chamber 41b. With this configuration, the high-pressure fuel oil in the oil passage hole 41c and the high-pressure fuel passage 8 is accumulated in the pressure accumulating chamber 41b through the throttle hole 41a, whereby the residual pressure in the nozzle chamber 11 is increased. In the prior art, an additional volume structure is provided to prevent gas from entering from the tip of the fuel injection valve. The effect is large, so it is used in some models.However, in the configuration that has a strainer structure at the inlet of the fuel injection valve, the combined use of the strainer and the additional volume part is subject to dimensional restrictions. It was difficult.

[0005]

SUMMARY OF THE INVENTION According to the present invention, an additional volume portion is provided inside a central portion of a strainer piece in order to combine the structure of the strainer as described above with the structure of the additional volume portion. Alternatively, the outer peripheral portion of the strainer piece is provided using half of the outer peripheral portion, and the remaining outer peripheral portion has a role as a strainer.

[0006]

The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described. In a first aspect of the present invention, in a fuel injection valve having a strainer provided in a fuel inlet passage, a pressure accumulating chamber a is formed in a strainer piece 1 constituting the strainer. In a fuel injection valve having a strainer provided in a fuel inlet passage, a strainer piece 1 constituting the strainer is provided with a pressure accumulating chamber a.
And the pressure accumulating chamber a is formed inside the central portion of the strainer piece 1. 4. The fuel injection valve according to claim 3, wherein the strainer is provided in the fuel inlet passage.
The pressure accumulating chamber a is formed on the outer periphery of the strainer piece 1.

[0007]

Next, an embodiment of the present invention will be described. FIG. 1 is an overall sectional view of a fuel injection valve having a strainer of the present invention, and FIG.
Front sectional view and a perspective view and a side sectional view of an assembled state of a strainer piece 1 showing an embodiment constructed inside a central portion of
3 is a front sectional view, an assembled perspective view, and a side sectional view of each part of an embodiment in which the pressure accumulating chamber a is formed on the outer peripheral portion of the strainer piece 1, and FIG. FIG. 5 is a front sectional view, a perspective view and a side sectional view of a conventional strainer piece constituting only a strainer, and FIG.

Referring to FIG. 1, the overall configuration of the fuel injection valve will be described. The adapter 2 is interposed on the side surface of the fuel injection valve body 16, and the strainer piece 1 is fitted inside the adapter 2. A fuel pipe 22 is connected to the strainer piece 1 and an outer periphery is connected by a female screw pipe 19 so as to prevent oil leakage. The fuel pipe 22 is supplied with high-pressure oil from a fuel injection pump. The high-pressure oil is filtered at the strainer piece 1, thereby filtering minute dust and dust contained in the high-pressure fuel oil.

The filtered high-pressure fuel oil passes through the high-pressure fuel passage 8 and also through the high-pressure fuel passage of the nozzle holder 13 and reaches the nozzle chamber 11. Then, the high-pressure fuel oil pushes up the nozzle needle 12 to move the nozzle needle 11 out of the nozzle 27.
Injected toward. Further, a spring chamber 14 is provided at an upper portion of the fuel injection valve main body 16, a compression spring 26 is arranged inside the spring chamber 14, and a push rod 24 with a vertical groove is pressed via a spring receiver 25.

The lower end of the push rod 24 with the vertical groove presses the nozzle needle 12 against the nozzle chamber 11.
Return oil enters the spring chamber 14 from the gap between the nozzle needle 12 and the nozzle holder 13 through the gap between the push rod 24 with the longitudinal groove and the fuel injection valve body 16, and enters the oil leak pipe 15 from the spring chamber 14. Is returned to the direction of the fuel tank.

In a diesel engine having a fuel injection valve, a pressure accumulating chamber a is configured to prevent fuel gas from entering the fuel injection valve. The pressure accumulating chamber a and the strainer portion are provided in the strainer piece 1 without any change in the fuel injection valve body. The intrusion of the combustion gas into the fuel injection valve occurs when the fuel oil pressure in the fuel injection valve, particularly in the nozzle chamber 11, becomes lower than the combustion gas pressure in the cylinder during the lift of the nozzle needle 12 of the fuel injection valve. This is a phenomenon in which the combustion gas enters the fuel injection valve from the cylinder.

When the amount of the infiltrating combustion gas increases, the infiltrating combustion gas flows to the nozzle needle 12 and the nozzle holder 13.
And the gap between the push rod 24 with the longitudinal groove and the fuel injector main body 16, the air bubbles come out of the oil leak pipe 15 through the spring chamber 14. As a result, the sliding of the nozzle needle 12 becomes worse, and there is a possibility that the needle sticks to the fuel injection valve. In the present invention, a pressure accumulating chamber a is provided to keep the residual pressure in the high-pressure fuel passage 8 high after the fuel is discharged, and the gas intrusion is prevented.
The pressure accumulating chamber a is provided integrally with the strainer piece 1, so that the components can be shared without increasing the number of components. 26 is a compression spring, 25 is a spring receiver, 23 is a case nut, and 19 is a female screw tube.

Next, referring to FIG.
An embodiment in which a pressure accumulating chamber a is formed in the center of the above will be described. The strainer piece 1 is press-fitted into the adapter 2 and fixed. The gap between the outer circumference of the strainer piece 1 and the inner circumference of the adapter 2 constitutes a passage through which high-pressure fuel oil passes. And is acting as a strainer.

The pressurized oil from the fuel pipe 22 flows from the inlet side semi-circular cut 1b to the outlet side semi-circular cut 1a. The gap forms a strainer. A pressure accumulating chamber a having a rectangular shape in a side view is formed in the center of the strainer piece 1. As shown in the side sectional view of FIG. 2, the pressure accumulating chamber a is formed as a rectangular parallelepiped hole penetrating the inside. The accumulator a
The narrow hole between the outer periphery of the strainer piece 1 and the inner periphery of the adapter 2 also serves as the throttle hole.

In the embodiment shown in FIG. 3, an embodiment in which a pressure accumulating chamber a is formed on the outer periphery of the strainer piece 1 is disclosed. Also in the present embodiment, the configuration in which the exit side semicircular cuts 1a and the entrance side semicircular cuts 1b are formed alternately at intervals is the same. And the exit side semicircle cut 1
a and the entrance side semicircle cut 1b are put together on the outer circumference of the semicircle,
The accumulator chamber a is formed around the outer periphery of the other semicircle. Also in this case, the narrow hole between the outer periphery of the strainer piece 1 and the inner periphery of the adapter 2 serves as the throttle hole for the pressure accumulating chamber a. The shape of the pressure accumulating chamber a is such that three types of side sectional views in FIG. 3 are disclosed,
The chord-shaped aa, the semi-circle arc aaa, the triangular arc arc a
aaa.

[0016]

According to the present invention, the following effects can be obtained by the above-described structure. In the fuel injection valve in which the strainer is provided in the fuel inlet passage, the strainer piece 1 constituting the strainer is provided with the pressure accumulating chamber a, thereby preventing dust from entering the fuel injection valve and preventing gas from entering. Both are now possible.

Since the pressure accumulating chamber a is formed inside the central portion of the strainer piece 1, the load capacity of the pressure accumulating chamber a can be increased, and the effect of suppressing gas intrusion can be improved. It was done.

Since the pressure accumulating chamber a is formed on the outer peripheral portion of the strainer piece 1, the pressure accumulating chamber a can be formed only by processing the outer circumference of the strainer piece 1, thereby facilitating the processing. It was.

[Brief description of the drawings]

FIG. 1 is an overall sectional view of a fuel injection valve having a strainer of the present invention.

FIG. 2 is a front sectional view, an assembled perspective view, and a side sectional view of the strainer piece 1 showing an embodiment in which a pressure accumulating chamber a is formed inside a central portion of the strainer piece 1.

FIG. 3 is a front sectional view, an assembled perspective view, and a side sectional view of each part of an embodiment in which a pressure accumulating chamber a is formed, and the pressure accumulating chamber a is formed on an outer peripheral portion of the strainer piece 1.

FIG. 4 is a front cross-sectional view, a perspective view, and a side cross-sectional view of a conventional technique in which only an additional volume portion is configured;

FIG. 5 is a front sectional view, a perspective view in an assembled state, and a side sectional view of a conventional strainer piece including only a strainer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Strainer piece 1a Outlet semicircle cut 1b Inlet semicircle cut a Pressure accumulation chamber 2 Adapter 8 High pressure fuel passage 11 Nozzle chamber 12 Nozzle needle 13 Nozzle holder

Claims (3)

[Claims] 1. A fuel injection valve in which a strainer is provided in a fuel inlet passage, wherein a pressure accumulating chamber (a) is formed in a strainer piece (1) constituting the strainer. 2. In a fuel injection valve having a strainer provided in a fuel inlet passage, a pressure accumulating chamber a is formed in a strainer piece 1 constituting the strainer, and the pressure accumulating chamber a is formed inside a central portion of the strainer piece 1. A fuel injection valve characterized in that: 3. In a fuel injection valve having a strainer provided in a fuel inlet passage, a strainer piece 1 constituting the strainer has a pressure accumulating chamber a formed therein, and the pressure accumulating chamber a is formed on an outer peripheral portion of the strainer piece 1. A fuel injection valve characterized by the above-mentioned.