JPH0625555U - Fuel injection pump for internal combustion engine - Google Patents

Abstract

(57) [Summary] [Object] An object of the fuel injection pump for an internal combustion engine of the present invention is to provide a fuel injection pump for an internal combustion engine capable of minimizing the occurrence of cavitation erosion. A structure is characterized in that an oil discharge port of a fuel injection pump is provided so as to incline upward in response to a pressure wave to the oil discharge port at the end of injection.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a fuel injection pump for an internal combustion engine.

[0002]

[Prior art]

 An example of a conventional diesel engine fuel injection pump will be described with reference to FIG. FIG. 2 is a cross-sectional view of the upper portion of the plunger barrel of the conventional fuel injection pump for diesel engine, showing the state at the end of injection. In the figure, 2 is a plunger barrel, and 1 is a plunger, which has a notched portion inclined with respect to the shaft and is fitted in the plunger barrel 1. 2a is an oil drain port which is opened perpendicularly to the center line of the plunger barrel 1. 3 is a deflector. 6 is cavitation erosion.

The operation of the conventional example will be described. The plunger 1 advances in the plunger barrel 2 and pushes fuel at the top of the plunger from an injection valve (not shown). The space at the top of the plunger communicates with the notch of the plunger, and when the plunger 1 moves and the notch communicates with the oil drain port 2a, the fuel at the top of the plunger passes through the notch of the plunger and the oil drain port. It flows to 2a and fuel injection ends. FIG. 2 is a diagram showing this state.

[0004]

[Problems to be solved by the device]

 However, the conventional example has a problem in that a high-pressure pressure wave discharged at a certain angle at the end of injection collides with the upper side of the oil discharge port, causing cavitation erosion at the relevant portion. An object of the present invention is to provide a fuel injection pump for an internal combustion engine which can solve the above-mentioned problems and reduce the occurrence of cavitation erosion as much as possible.

[0005]

A fuel injection pump for an internal combustion engine according to the present invention is characterized in that an oil discharge port is provided so as to be inclined upward to prevent the occurrence of cavitation erosion in the portion.

[0006]

[Action]

 Since the pressure wave at a certain angle at the end of injection of the fuel injection pump is directed in substantially the same direction as the oil discharge port, it does not collide with the oil discharge port wall and reduces the occurrence of cavitation erosion in this portion.

[0007]

【Example】

 An embodiment will be described with reference to FIG. FIG. 1 is a sectional view of the upper portion of the plunger barrel of the embodiment. In the figure, 2 is a plunger barrel, and 1 is a plunger, which has a notched portion inclined to its axis and is fitted in the plunger barrel 1. An oil drain port 2a is provided in the cylinder barrel 2 so as to be inclined upward with respect to the shaft. 4 is the pressure wave at a certain angle at the end of injection. Reference numeral 5 denotes an inclination angle, which is an angle formed by the oil drain port 2a with respect to a straight line perpendicular to the center line of the plunger barrel 2, and is an appropriate angle which is substantially concentric with the pressure wave 4 at the end of injection.

The operation of the above embodiment will be described. The plunger 1 advances in the plunger barrel 2 and pushes the fuel above the top of the plunger from an injection valve (not shown). Since the top of the plunger communicates with the notch of the plunger, when the plunger moves and the notch communicates with the oil drain port 2a, the fuel at the top of the plunger passes through the notch to the oil drain port 2a. Fuel injection ends because it flows. Since the pressure wave 4 at a certain angle at the end of fuel injection and the drain port 2a are substantially concentric, the pressure wave 4 at a certain angle at the end of injection does not directly collide with the wall of the drain port 2a.

[0009]

[Effect of device]

 Since the present invention is configured as described above, the high-pressure pressure wave at the end of fuel injection does not directly collide with the wall of the oil drain port of the plunger barrel, so that cavitation erosion does not occur in that portion. Therefore, the present invention can provide a fuel injection pump for an internal combustion engine that can minimize the occurrence of cavitation erosion.

[Brief description of drawings]

FIG. 1 is a sectional view of an upper portion of a plunger barrel of an embodiment.

FIG. 2 is a cross-sectional view of a conventional plunger barrel upper portion.

[Explanation of symbols]

1 ... Plunger, 2 ... Plunger barrel, 2a ... Oil discharge port, 4 ... Pressure wave, 5 ... Inclination angle, 6 ... Cavitation erosion.

Claims (1)

[Scope of utility model registration request] 1. A fuel injection pump for an internal combustion engine, characterized in that an oil discharge port (2a) of the fuel injection pump is provided so as to be inclined upward to prevent the occurrence of cavitation erosion (6) in that portion.