JPH0441248Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to the structure of a high-pressure injection fuel injection pump.

(Prior Art) A high-pressure fuel injection pump with a suspended plunger barrel is known. An example of this type of fuel injection pump is shown in Figure 2 (Japanese Patent Laid-Open Publication No.
60-128969), a plunger barrel 2 is suspended within a pump body 1, and a valve body 3 is constructed by screwing a valve holder 4 and a valve seat 5 in advance. is inserted into the recess 6 formed in the upper part of the plunger barrel 2, and the valve holder 4 and the pump body 1 are tightened and fixed with a tightening bolt 7. A plunger 8 is fitted into the plunger barrel 2 , and by lifting the plunger 8 , fuel oil sent from the fuel inlet 9 via the fuel suction hole 10 is forced into the fuel compression chamber 11 and passed through the discharge valve 12 . The liquid is then sent to an injection nozzle (not shown). This pressure feeding of fuel oil ends when the lead 13 of the plunger 8 reaches the fuel suction hole 10. At this time, the fuel oil is in the fuel compression chamber 11
Flow from the plunger 8 through the vertical groove 14, lead 13, and fuel suction hole 10 causes the fuel suction hole 1 to flow backward.
A deflector 15 is provided on the pump body 1 at a location opposite to the pump body 1 to prevent corrosion of the pump body.
Furthermore, a fuel reservoir chamber 16 provided at the fuel inlet 9
An O-ring 17 is disposed below the plunger barrel 8 and the pump body 1 to prevent fuel oil from leaking.

(Problems to be Solved by the Invention) In the high-pressure fuel injection pump having the above configuration, a high-pressure reflected flow is produced at the end of fuel oil pressure transmission as described above, so that the fuel oil due to this backpressure is transferred to the plunger barrel 2 and the pump. It reaches the O-ring 17 through the gap with the main body 1. The O-ring 17 is originally intended to prevent oil leakage due to such fuel oil, but since the fuel injection pump is of a high pressure type, it gradually corrodes and causes a problem of oil leakage.

On the one hand, since the plunger barrel 2 is structurally incorporated into the pump body 1, a certain amount of clearance is required between the two, and on the other hand, in practice,
High-pressure fuel injection pumps with large shaft output tend to use heavy oil with relatively high viscosity, so some clearance is required between the two to avoid sticking due to heavy oil. Then,
The above-mentioned corrosion effect of the O-ring becomes noticeable, and improvement thereof has been desired.

(Means for Solving the Problems) The present invention has been made in view of the above circumstances, and an object of the present invention is to obtain a fuel injection pump having a simple structure that can prevent corrosion of the O-ring.

That is, in the present invention, a plunger barrel is fitted into the pump main body, a fuel suction hole is formed in the plunger barrel communicating with the fuel inlet of the pump main body, and the plunger fitted into the plunger barrel pumps fuel oil. In a fuel injection pump of a type in which the lead of the plunger ends at the position where it reaches the fuel suction hole, the fuel injection pump is located between a fuel reservoir provided at the fuel inlet and the O-ring,
The present invention provides a fuel injection pump in which an oil pocket is formed by providing an oil reservoir space between the plunger barrel and the pump body.

(Function) The fuel oil that enters the gap between the plunger barrel and the pump body due to the backpressure expands at the oil pocket and is therefore depressurized, thereby avoiding high-pressure erosion of the O-ring.

(Example) The fuel injection pump of the present invention will be described below based on an example. Note that the same reference numerals are given to the same components as in the conventional example.

In the present invention, as shown in FIG. 1, a plunger barrel 2 is fitted into a pump body 1, a fuel suction hole 10 is formed in the plunger barrel 2 so as to communicate with a fuel inlet 9 of the pump body 1, and the plunger barrel 2 is fitted into the plunger barrel 2. This type of fuel injection pump is used in which the pressure feeding of fuel oil by the plunger 8 ends at the position where the lead 13 of the plunger reaches the fuel suction hole 10. Furthermore, between the fuel reservoir chamber 16 provided at the fuel inlet 9 and the O-ring 17,
An oil pocket 18 is provided with an oil reservoir space between the plunger barrel 2 and the pump body 1.
was formed.

The oil pocket 18 is formed by cutting out the pump body 1 or in the plunger barrel 2, but it may also be formed by cutting out both positions corresponding to the same position. Although the oil pocket 18 may be one or more, and may have any size or shape, it is preferable that the oil pocket 18 be provided with a gap therebetween, rather than communicating directly with the fuel reservoir chamber 16. As a result, the fuel oil caused by the backpressure is blocked in stages, such as in the fuel reservoir chamber 16 in the first stage and in the oil pocket 18 in the second stage, and the pressure is reduced as quickly as possible. be able to. In the embodiment, the oil pocket 18
is formed in a ring shape slightly below the fuel reservoir chamber 16. Incidentally, since the above-mentioned backflow of fuel oil occurs intermittently, from the viewpoint of protecting the O-ring, it is sufficient to remove the instantaneous high pressure, and therefore even a relatively small oil pocket can perform a depressurizing action.

(Effect of the invention) As explained above, in the present invention, a plunger barrel is fitted into the pump body, a fuel suction hole is formed in the plunger barrel that communicates with the fuel inlet of the pump body, and the plunger barrel is fitted into the plunger barrel. In a fuel injection pump of a type in which the pressure feeding of fuel oil by a plunger ends at the position where the lead of the plunger reaches the fuel suction hole, there is a gap between a fuel reservoir provided at the fuel inlet and the O-ring. Since an oil pocket with an oil storage space is formed between the plunger barrel and the pump body, the fuel oil that enters the gap between the plunger barrel and the pump body due to the backpressure is absorbed into the oil pocket. The pressure is reduced due to expansion in the O-ring, thereby avoiding high-pressure loading on the O-ring, thereby preventing erosion of the O-ring, and thus preventing oil leakage from the O-ring as in the conventional case. It became. Furthermore, since this oil pocket is created by simply forming a notch, it can be implemented extremely easily, and a great practical advantage can be obtained due to the low manufacturing cost.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view of a main part of a fuel injection pump embodying the present invention, and FIG. 2 is a vertical cross-sectional view showing the fuel injection pump. 1...Pump body, 2...Plunger barrel,
8...Plunger, 9...Fuel inlet, 10...Fuel suction hole, 13...Lead, 16...Fuel reservoir chamber, 17...O ring, 18...Oil pocket.

Claims (1)

[Scope of utility model registration request] A plunger barrel is inserted into the pump body,
A fuel suction hole is formed in the plunger barrel so as to communicate with the fuel inlet of the pump body, and the pressure feeding of fuel oil by the plunger fitted into the plunger barrel ends when the lead of the plunger reaches the fuel suction hole. In the fuel injection pump of
between a fuel reservoir provided at the fuel inlet and an O-ring disposed between the plunger barrel and the pump body below the fuel reservoir,
A fuel injection pump characterized in that an oil pocket having an oil reservoir space is formed between the plunger barrel and the pump body.