JP2550758B2 - Fuel injection pump pressure control valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention enables a fuel injection pump for a diesel engine to set a constant internal pressure of a fuel pipe between a pressure chamber and an injection nozzle at the end of injection. The present invention relates to a pressure control valve for a fuel injection pump.

[Prior art]

In recent years, noise from diesel vehicles and environmental pollution due to exhaust gas have become social problems. In order to cope with the above problems as a fuel injection pump, it is essential to increase the injection pressure of the fuel injection pump.

However, as the injection pressure is increased, the internal pressure of the injection nozzle is increased to cause a secondary injection state, and problems such as cavitation in the fuel pipe up to the injection nozzle occur. , For example, JP-A-60
As described in JP-A-119366, there is a method of mounting a pressure regulating valve on a fuel injection pump. The pressure regulating valve is provided with a return valve for returning the residual pressure in the injection nozzle after the injection is completed to the pressurizing chamber.

That is, the pressure adjusting valve of the fuel injection pump is, for example, as shown in FIGS. 7 to 9, a fuel supply valve 92 for supplying fuel from the pressurizing chamber 911 to the injection nozzle 99, and an injection nozzle at the end of injection. It has a return valve 95 for returning the residual pressure therein to the pressurizing chamber 911.

The fuel supply valve 92 includes a valve seat 921 fixed to the cylinder 91 of the fuel injection pump, and a valve 922 that can be seated on a valve seat 923 formed on the valve seat 921.
The valve 922 is a valve holder 93 mounted on the cylinder 91.
In the inner fuel supply valve chamber 931, the spring 94 constantly urges the valve in the valve closing direction.

The valve 922 lifts in the valve opening direction against the urging pressure of the spring 94 when the pressure in the pressurizing chamber 911 becomes larger than the urging pressure of the spring 94. As a result, the pressure chamber 91
The fuel in 1 is the fuel supply valve chamber 931, the passage 932, and the fuel pipe 98.
Through and into the injection nozzle 99. Then, when the pressure of the fuel becomes equal to or higher than the valve opening pressure of the injection nozzle 99, the fuel is injected from the injection nozzle 99.

The return valve 95 includes a snubber 951 fixed to the fuel supply valve 92, a spring seat 953 installed in a return valve chamber 925 inside the fuel supply valve 92, and an internal pressure adjusting ball 952 interposed therebetween. Consists of. The internal pressure adjusting ball 952 is
It can be seated on a valve seat 955 formed by expanding the snubber 951. The spring seat 953 is normally urged by the spring 96 in the valve closing direction of the internal pressure adjusting ball 952.

When the pressure in the fuel pipe 98 is higher than the biasing pressure of the spring 96 after fuel injection, the internal pressure adjusting ball 952 lifts in the valve opening direction against the biasing pressure of the spring 96. As a result, the fuel in the fuel pipe 98 passes through the passage 954,
Return to the pressurizing chamber 911 through the return valve chamber 925 and the passage 924. And
When the residual pressure in the fuel pipe 98 and the biasing pressure of the spring 96 are balanced, the return of fuel is completed. Therefore, the residual pressure in the fuel pipe 98 is always kept constant.

[Problems to be solved]

However, in the pressure adjusting valve of the conventional fuel injection pump, there is a possibility that the constant residual pressure function, which is the original function of the pressure adjusting valve, cannot be maintained.

This point will be described in detail with reference to FIG. That is, at the time of returning the fuel, the internal pressure of the fuel reflected wave from the injection nozzle pushes down the internal pressure adjusting ball 952. The internal pressure has a very high pressure energy and is discharged along the expansion surface of the valve seat 955 which is expanded and formed in the snubber 951.

Here, the expansion angle of the valve seat 955 is θ955, the outer diameter of the facing surface 956 is D956, the extension line of the expanding surface of the valve seat 955 and the facing surface 956.
The outer diameter of the intersection with (the upper surface of the spring seat 953) is D
955, The expansion angle of the portion of the spring seat 953 corresponding to the above extension line is θ953. At this time, the relationship of D955 <D956 θ955 <θ953 is established.

Therefore, the pressure wave of the fuel discharged along the expanding surface of the valve seat 955 hits the facing surface 956 strongly. Therefore, the lift amount of the internal pressure adjusting ball 952 becomes excessive. as a result,
The amount of fuel relief changes significantly, making it impossible to maintain the constant residual pressure, which is the original function of the pressure regulating valve. As described above, the pressure regulating function of the conventional pressure regulating valve may deteriorate.

In view of the above conventional problems, the present invention is to provide a pressure regulating valve for a fuel injection pump, which can prevent an excessive lift of an internal pressure regulating ball and can perform accurate pressure regulation.

[Means for solving problems]

The present invention has a fuel supply valve for supplying fuel from the pressurizing chamber to the injection nozzle, and a return valve for returning the residual pressure in the injection nozzle at the end of injection to the pressurizing chamber. The valve is composed of a snubber, a spring seat, and an internal pressure adjusting ball interposed between the snubber and the spring seat. The internal pressure adjusting ball is a pressure adjusting valve of a fuel injection pump which is seated on a valve seat formed by expanding the snubber. The outer diameter D11 of the snubber facing surface of the spring seat is smaller than the diameter D955 of the intersection of the extension line S of the expanding surface of the snubber valve seat and the extension line of the snubber facing surface, and the outer surface of the spring seat is A pressure regulating valve for a fuel injection pump, characterized in that it has a taper portion that extends outward from the outer peripheral edge of the surface facing the snubber, and the expansion angle θ12 of the taper portion is smaller than the expansion angle θ955 of the valve seat. It is in .

What is most noticeable in the present invention is that the outer diameter of the snubber facing surface that receives the fuel pressure is made small in order to smooth the flow of fuel to the pressurizing chamber at the time of returning fuel (that is, as described above, D11 <D955), and the taper is provided on the outer surface of the spring seat, and the expansion angle θ of the taper is
12 is smaller than the valve seat expansion angle θ955 as described above,
(That is, θ12 <θ955).

[Work]

In the present invention, when the internal pressure adjusting ball is opened by the fuel pressure wave after the fuel injection, this fuel pressure wave is released along the expansion surface of the valve seat that is expanded and formed in the snubber.

At this time, the outside diameter D11 of the snubber facing surface as the pressure receiving surface of the fuel pressure wave is smaller than the diameter D955 of the intersection of the extension line S of the expanding surface and the extension line of the snubber facing surface in the valve seat (D11 < D955), and the expansion angle θ12 of the taper that forms the fuel pressure wave flow path is the expansion angle θ95 of the valve seat.
Less than five.

Therefore, the fuel pressure wave does not hit the snubber facing surface strongly and forms a smooth flow along the tapered portion. Then, the fuel is smoothly returned to the pressurizing chamber.

Therefore, the pressure in the valve opening direction that acts on the internal pressure adjusting ball is accurately transmitted to the spring that elastically supports the internal pressure adjusting ball. Therefore, the lift amount of the internal pressure adjustment ball is stable and the pressure adjustment is accurate.

[Effect]

Therefore, according to the present invention, it is possible to provide a pressure adjusting valve for a fuel injection pump that can prevent an excessive lift of the internal pressure adjusting ball and perform accurate pressure adjustment.

〔Example〕

First Embodiment A pressure adjusting valve of a fuel injection pump according to an embodiment of the present invention will be described with reference to FIGS. 1 to 3 and the seventh embodiment shown in the prior art.
This will be described with reference to the drawings.

The pressure adjusting valve of this example is configured such that the fuel supply valve 92 for supplying fuel from the pressurizing chamber 911 to the injection nozzle 99 and the residual pressure in the injection nozzle 99 at the end of injection are controlled by the pressurizing chamber 911 (the above is 7
(See the drawing) and a return valve 2. The return valve 2 is composed of a snubber 951, a spring seat 1 and an internal pressure adjusting ball 952 provided between them. The internal pressure adjusting ball 952 is arranged so as to be seated on the valve seat 955 formed in the snubber 951.

The surface of the spring seat 1 facing the snubber
The outer diameter D11 of 11 is located inside the extension line S of the expansion surface of the valve seat 955 of the snubber 951. The outer surface of the spring seat 1 is a surface facing the snubber.
It has a tapered portion 12 extending outward from the outer peripheral edge of 11. The expansion angle θ12 of the tapered portion 12 is smaller than the expansion angle θ955 of the valve seat 955.

As shown in FIGS. 1 and 2, the snubber facing surface 11 is formed around the internal pressure adjusting ball 952 so as to face the snubber 951. The outer diameter D11 of the snubber facing surface 11 is
Diameter of the intersection of the extension line S of the expansion surface of the valve seat 955 of the snubber 951 and the extension line of the snubber facing surface 11 (horizontal line in the figure)
It is smaller than the D955.

The tapered portion 12 is formed along the outer surface of the head of the spring seat 1. The tapered portion 12 is formed so as to expand outward from the outer peripheral edge of the facing surface 11. Further, the taper portion 12 is formed such that the expansion angle θ12 thereof is smaller than the expansion angle θ955 of the valve seat 955 formed by expanding the snubber 951.

That is, in this example, the spring seat 1 is formed so as to satisfy the following two conditions.

D11 <D955 θ12 <θ955 Others are the same as in the conventional example.

Since the pressure regulating valve of this example is configured as described above, the following operational effects are exhibited.

That is, after fuel injection, the fuel pressure wave from the injection nozzle is transmitted to the internal pressure adjusting ball 952 of the return valve 2 via the passage 954 of the snubber 951. When the pressure of the fuel pressure wave becomes larger than the biasing pressure of the spring 96, the fuel pressure wave resists the biasing pressure of the spring 96 and lifts the internal pressure adjusting ball 952 in the valve opening direction.

When the internal pressure adjusting ball 952 opens, the fuel pressure wave is released into the return valve chamber 925 along the expanded surface of the valve seat 955 formed by expanding the snubber 951.

At this time, the outer diameter of the snubber facing surface 11 is located inside the extension line of the expansion surface of the valve seat 955 (D1
1 <D955). Therefore, since the pressure receiving area on the snubber facing surface 11 is small, the fuel pressure wave does not hit the snubber facing surface 11 strongly. Then, the pressure acting on the internal pressure adjusting ball 952 in the valve opening direction is accurately transmitted to the spring 96.

Further, the expansion angle of the tapered portion 12 is smaller than the expansion angle of the valve seat 955 (θ12 <θ955). Therefore, the fuel pressure wave forms a smooth flow along the tapered portion 12. Then, the fuel is supplied to the pressurizing chamber 911 through the return valve chamber 925 and the passage 924.
Will be returned smoothly to.

As a result, as shown in FIG. 3, in the present example (shown by A), the internal pressure adjusting ball 952 does not lift excessively as in the conventional case (shown by B), and the relief amount of the fuel is stabilized. Moreover, the constant residual pressure function, which is the original function of the pressure regulating valve, can be maintained.

Further, since the lift amount of the internal pressure adjusting ball 952 is small and stable, the amount of wear of the internal pressure adjusting ball 952 and the valve seat 955 is reduced.

 Therefore, the reliability of the pressure control valve is greatly improved.

Second Embodiment The pressure regulating valve of this embodiment will be described with reference to FIGS. 4 and 5.

In this example, instead of the spring seat 1 shown in the first embodiment, a partially cut-out spring seat 3 is used. The spring seat 3 is formed by cutting off three surfaces of the spring seat 1 of the first embodiment along the axial direction thereof to form a fuel passage 30.

 Others are the same as those in the first embodiment.

Since the pressure regulating valve of this example is configured as described above, when the fuel is returned, the fuel is supplied to the pressurizing chamber 911 by the fuel passage 30.
Flows smoothly in the direction.

Further, the same effect as that of the first embodiment can be obtained.

Third Embodiment The pressure regulating valve of this embodiment will be described with reference to FIG.

Whereas the return valve 95 is provided inside the fuel supply valve 92 in the first and second embodiments, the fuel supply valve 4 and the return valve 5 are arranged in series in this embodiment.

That is, the fuel supply valve 4 includes a valve seat 921 having a valve seat 923 and a valve 922 that also serves as the snubber of the return valve 5. A passage 954 is axially provided through the valve 922.

Further, the return valve 5 includes a valve 922 as a snubber,
It comprises a spring seat 1 and an internal pressure adjusting ball 952 provided between the spring seat 1 and the internal pressure adjusting ball 952.
It is adapted to be seated on the valve seat 955 which is formed by expanding. The return valve chamber 925 shown in the first embodiment is the valve seat 921.
Formed inside. The return valve chamber 925 has a spring receiver 5
It communicates with the pressurizing chamber through a through hole 50 formed in 1.

Also in this example, the two conditions D11 <D955,
θ12 <θ955 is satisfied.

 Others are the same as those in the first embodiment.

Since the pressure regulating valve of this example is configured as described above, it exhibits the following operational effects.

That is, when the valve 922 is lifted at the time of fuel supply, the spring seat 1 and the internal pressure adjusting ball 952 are also moved in the lifting direction by the urging force of the spring 96. Therefore, the return valve 5 is closed during fuel supply.

On the other hand, at the time of returning the fuel, the valve 922 is seated and the internal pressure adjusting ball 95 is seated as shown in the first embodiment.
2 lifts and adjusts the residual pressure in the fuel pipe to a constant pressure. The action and effect at the time of returning the fuel are similar to those of the first embodiment.

[Brief description of drawings]

1 to 3 show a pressure regulating valve of a combustion injection pump according to a first embodiment, and FIG. 1 is an enlarged sectional view of a main part thereof, and FIG.
The drawing is a sectional view taken along the line X-X in FIG. 1, FIG. 3 is a diagram showing the lift amount of the internal pressure adjusting ball of the return valve, and FIGS. 4 and 5 are the pressure adjusting according to the second embodiment. FIG. 4 shows a spring seat of the valve, FIG. 4 is an enlarged sectional view thereof, FIG. 5 is a plan view thereof, FIG. 6 is a sectional view of a pressure regulating valve according to a third embodiment, and FIGS. An example is shown, FIG. 7 is a sectional view of the pressure regulating valve, FIG. 8 is an enlarged sectional view of an essential part thereof, and FIG. 9 is a sectional view taken along the line YY in FIG. 1 ... Spring seat, 11 ... Snubber facing surface, 12 ... Tapered part, 2 ... Return valve, 3 ... Spring seat, 4 ... Fuel supply valve, 5 ... Return valve, 911 ... Pressurization chamber , 92 ...... Fuel supply valve, 951 ...... Snubber, 952 ...... Internal pressure adjusting ball, 99 ...... Injection nozzle,

Claims (1)

(57) [Claims] 1. A fuel supply valve for supplying fuel from a pressurizing chamber to an injection nozzle, and a return valve for returning residual pressure in the injection nozzle at the end of injection to the pressurizing chamber. The return valve is composed of a snubber, a spring seat, and an internal pressure adjusting ball provided between the two, and the internal pressure adjusting ball is a pressure adjusting valve of a fuel injection pump which is seated on a valve seat formed by expanding the snubber. Outer diameter D1 of the surface facing the snubber in the spring seat
1 is smaller than the diameter D955 of the intersection of the extension line S of the expansion surface of the snubber valve seat and the extension line of the snubber facing surface, and the outer surface of the spring seat is outside the outer peripheral edge of the snubber facing surface. A pressure regulating valve for a fuel injection pump, which has a taper portion directed toward one side, and an expansion angle θ12 of the taper portion is smaller than an expansion angle θ955 of the valve seat.