JPH09151832A - Fuel injection pump for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the generation of excessive surface pressure and prevent the generation of seizure and rough surface caused by contact between a plunger and a plunger barrel by forming the tip part of the plunger reciprocated in the plunger barrel by a cam of a plunger type fuel injection pump, into tapered circular cone shape. SOLUTION: A tip part 2 of a plunger 1 slidably fitted to a plunger barrel 5 in a plunger type fuel injection pump is formed into a tapered circular cone. Accordingly, even if the plunger 1 is inclined in the plunger barrel 5, the tip does not come in contact so as to hardly generate excessive surface pressure and to improve fuel oil lapping-in ability, thus feeding oil smoothly to the sliding face of the plunger 1. It is also desirable to form in such a way as to connect the conical shape 2 of the plunger tip part 1a and a cylindrical part thereunder by smooth circular arc shape, and gentle circular arc shape is provided from the top face of the plunger 1 to its drum part so as to further improve its action.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plunger type fuel injection pump for an internal combustion engine.

[0002]

2. Description of the Related Art A conventional plunger type fuel injection pump for an internal combustion engine will be described with reference to FIGS. FIG. 4 is an explanatory view of a fuel injection system using a conventional plunger-type fuel injection pump, and FIG. 5 is a sectional view of a plunger tip portion of a conventional fuel injection pump for an internal combustion engine. In the figure, the plunger 1 is pushed up in the plunger barrel 5 by the cam 10 that rotates in synchronization with the rotation of the engine, and after the tip of the plunger 1 closes the fuel supply hole 7, the fuel in the plunger barrel 5 is filled with fuel. Is injected into the cylinder 9 of the engine. The plunger 1 has a cylindrical shape for the purpose of blocking the fuel supply hole 7 at its tip portion 1a and maintaining oil tightness.

[0003]

An appropriate gap is provided between the plunger 1 and the plunger barrel 5 in order to keep the oil tightness in the cylinder and to allow the plunger 1 to slide smoothly. When 1 is tilted by this distance, the right angle portion of the plunger tip 1a contacts the inner surface of the plunger barrel 5, and there is a risk of seizure or rough skin due to excessive surface pressure, which would prevent normal operation of the engine. Not
It may be impossible to suddenly stop or restart the engine.

Further, since the plunger tip 1a has a right-angled shape, it is difficult to supply the fuel oil required for the sliding lubrication of the plunger 1 downward, and the plunger 1 and the plunger barrel 5 come into contact with each other. It may occur.

An object of the present invention is to provide a fuel injection pump for an internal combustion engine, in which the tip of the plunger does not come into contact with the plunger barrel, oil licking is improved, and seizure between the plunger and the plunger barrel and skin roughening can be prevented. To provide.

[0006]

A fuel injection pump for an internal combustion engine according to a first aspect of the invention is characterized in that it has a conical plunger with a tapered tip. A fuel injection pump for an internal combustion engine according to a second aspect of the present invention is characterized in that it has a plunger having a tapered cone at its tip and an arcuate rotary body in contact with the cone and a cylindrical portion of the plunger.

A fuel injection pump for an internal combustion engine according to a third aspect of the present invention is characterized in that it has a plunger having a tip end portion which is in contact with a cylindrical portion of the plunger and is formed of a rotating body having an outwardly convex arc.

1, a conical shape 2 at the plunger tip 1a
Even if the plunger 1 is tilted due to the provision of the
The right-angled portion does not hit the plunger barrel 5, and it becomes difficult for excessive surface pressure to occur. Further, the licking property of the fuel oil for lubrication is improved, and the oil is easily supplied to the sliding surface of the plunger 1.

2, the conical shape 2 of the plunger tip 1a
The action of the above 1 is further improved by connecting the above and the cylindrical portion thereunder with a smooth arc shape 3. 3. By providing the gentle arcuate shape 4 from the top surface of the plunger 1 to the body portion, the action is further improved than the above-mentioned 1, 2.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION First, second and third embodiments of the present invention will be described.
An example will be described. FIG. 1 is a view of the tip of the plunger of the first embodiment, (a) is a sectional view, and (b) is a front view. In the figure, the tip portion 2 of the plunger 1 which is slidably fitted in the plunger barrel 5 in the axial direction is formed into a tapered cone having a half apex angle larger than the maximum angle at which the plunger tilts in the plunger barrel. The structure other than the plunger is the same as that of the known combustion injection pump.

The operation of the first embodiment will be described. Even if the plunger 1 is tilted in the plunger barrel 5, its tip does not come into contact with the plunger barrel 5, so that excessive surface pressure is unlikely to occur. Further, the licking property of fuel oil is also improved, and oil is supplied to the sliding surface of the plunger. FIG. 2 is a view of the tip of the plunger of the second embodiment (a).
Is a cross-sectional view, (b) is a front view, and (c) is a yard view. In the figure, the tip of the plunger 1 that is movably fitted to the plunger barrel 5 is a cone 2 similar to the tip of the plunger of the first embodiment, and an arcuate rotor 3 that is in contact with the cone and the cylinder of the plunger 1. It is composed of. Others are the same as those in the first embodiment. The operation of the second embodiment improves the operation described in the first embodiment.

3A and 3B are views of the tip of the plunger of the third embodiment, FIG. 3A being a sectional view, FIG. 3B being a front view, and FIG. In the figure, the tip end of the plunger 1 that is movably fitted in the plunger barrel 5 is constituted by a rotating body 4 which is in contact with the cylindrical portion of the plunger and which is convex outward. Others are the same as those in the first embodiment. The operation of the third embodiment is the same as the first,
The operation is the same as that described in the second embodiment.

[0013]

EFFECTS OF THE INVENTION Since the right-angled portion of the plunger tip does not contact the plunger barrel, the occurrence of excessive surface pressure is suppressed, and the improved oil licking property causes seizure and rough skin due to the contact between the plunger and the plunger barrel. Can be prevented. Moreover, the life of the fuel injection pump itself is extended, and the reliability of the engine is improved.

[Brief description of the drawings]

FIG. 1 is a view, a sectional view, and a front view of a tip portion of a plunger according to a first embodiment of the present invention.

FIG. 2 is a view of a plunger tip portion of a second embodiment according to the present invention, (a) a cross-sectional view, (b) a front view, and (c) an enlarged view of a wheel sill portion.

FIG. 3 is a diagram of a plunger tip portion of a third embodiment according to the present invention, (a) a cross-sectional view, (b) a front view, and (c) an enlarged view of a wheel sill portion.

FIG. 4 is a schematic diagram of a fuel injection system of an internal combustion engine.

FIG. 5 is a relationship diagram of a plunger and a plunger barrel of a conventional fuel injection pump.

[Explanation of symbols]

1 ... Plunger, 1a ... Plunger tip, 2 ... Cone,
3 ... Arc rotating body, 5 ... Plunger barrel, 6 ... Fuel injection pump, 7 ... Fuel supply hole, 8 ... Fuel injection valve, 9 ... Engine cylinder, 10 ... Cam.

Claims (3)

[Claims] 1. A fuel injection pump for an internal combustion engine having a conical plunger with a tapered tip. 2. A fuel injection pump for an internal combustion engine, comprising: a plunger having a tapered cone at a front end thereof, and an arcuate rotor which is in contact with the cone and in contact with the cylindrical portion of the plunger. 3. A fuel injection pump for an internal combustion engine, which has a plunger having a tip end portion which is in contact with a cylindrical portion of the plunger and which is a rotating body having an outwardly convex arc.