Fluid handling – Line condition change responsive valves – Direct response valves
Reexamination Certificate
2001-05-25
2003-09-23
Rivell, John (Department: 3753)
Fluid handling
Line condition change responsive valves
Direct response valves
C137S536000
Reexamination Certificate
active
06622752
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a pressure relief valve, and more particularly to a pressure relief valve, which mounts to a pressure accumulator (common rail) and other such pressure apparatus for a fuel supply system or fuel injection system of an internal combustion engine, such as a gasoline engine or diesel engine.
2. Description of the Related Art
A conventional pressure relief valve comprising a common rail and the like will be explained in general terms based on FIG.
7
and FIG.
8
.
FIG. 7
is a simplified diagram of an example of a conventional internal combustion engine fuel injection system
1
, the fuel injection system
1
having a fuel tank
2
, a pressure pump
3
, a common rail
4
, a pressure relief valve
5
, and an injector
6
.
Pressure relief valve
5
functions as a safety valve for maintaining the pressure inside common rail
4
at less than a prescribed value, and, in addition, also functions as a pressure control valve when a pressure pump
3
control valve (not shown in the figure) malfunctions.
When this pressure relief valve
5
is mounted to common rail
4
, the problem is that, in a conventional structure, the pressure relief valve
5
is long, jutting out lengthwise from the side of common rail
4
, and, in addition, a completely sealed structure is difficult to achieve, the shape of the spring seat is complex, and it is costly.
FIG. 8
is a cross-sectional view of pressure relief valve
5
, pressure relief valve
5
having a valve holder
7
, a valve seat
8
, a ball valve
9
(valve body), a spring seat
10
, a valve spring
11
, a sealing ball
12
, and a filter
13
.
Valve holder
7
has a high-pressure portion side end portion
7
A, which faces the high-pressure portion side H of the inside of common rail
4
, and a low-pressure portion side end portion
7
B, which faces the low-pressure portion side L of the outside, and is integrated with valve seat
8
by a weld portion
14
in accordance with laser welding, and in a state, wherein valve spring
11
is housed on the inside thereof, the inside thereof is sealed by sealing ball
12
, which is press-fitted from the low-pressure portion side end portion
7
B.
Furthermore, valve holder
7
is fastened to common rail
4
by a snap ring
15
, and the high-pressure portion side H of common rail
4
and the low-pressure portion side L of common rail
4
are sealed by a first O-ring
16
.
Valve seat
8
forms a valve seat surface
17
in which ball valve
9
is seated, and when ball valve
9
is lifted from valve seat surface
17
, the high-pressure portion side H is connected to the atmospheric-pressure fuel tank
2
side via a linking passage
18
of the high-pressure side of valve seat surface
17
and a radial passage
19
of the low-pressure side, enabling the circulating flow of high-pressure fuel.
A backup ring
20
and a second O-ring
21
are provided for valve seat
8
, sealing the high-pressure portion side H and the low-pressure portion side L.
Spring seat
10
is inside valve seat
8
, slides axially therein, and seats valve spring
11
between itself and sealing ball
12
, and, in addition, causes ball valve
9
to make contact at a prescribed injection valve opening pressure with valve seat surface
17
of valve seat
8
in accordance with the biasing force of valve spring
11
.
A flat cut
22
is formed axially in spring seat
10
, enabling the linkage of the spring chamber
23
of valve spring
11
and the valve chamber
24
of ball valve
9
.
In a pressure relief valve
5
of a constitution such as this, the pressure inside the high-pressure portion side H of the common rail
4
is extremely high, and when this pressure is greater than the injection valve opening pressure resulting from valve spring
11
, ball valve
9
is lifted from valve seat surface
17
of valve seat
8
against the biasing force of valve spring
11
, and pressure escapes from the high-pressure portion side H to the fuel tank
2
side via linking passage
18
, valve chamber
24
and radial passage
19
.
However, the problem is that valve holder
7
of pressure relief valve
5
juts out far from common rail
4
, and, in addition, because spring chamber
23
of valve holder
7
is closed off or sealed by only sealing ball
12
, there is the possibility of fuel leaking to the outside from spring chamber
23
.
Furthermore, spring seat
10
has a complex shape, and, in addition, there is the possibility of radial external force acting on spring seat
10
in line with the operation of valve spring
11
, raising concerns of unstable operation, and, in addition, the durability thereof is a problem.
Further, the problem is that the position of ball valve
9
, which receives the flow of fuel, is unstable, and there is the likelihood that hunting will occur.
Pressure relief valves are disclosed in, for example, Japanese Patent Application Laid-open No. H9-105473, and Japanese Patent Application Laid-open No. H11-182242.
SUMMARY OF THE INVENTION
With the foregoing problems in view, it is an object of the present invention to provide a pressure relief valve in which the valve holder does not jut far out from the common rail.
Further, an object of the present invention is to provide a pressure relief valve in which a reliable sealing structure is achievable in the valve holder.
Further, an object of the present invention is to provide a pressure relief valve, which is capable of being manufactured at low cost, and is capable of being made compact.
Further, an object of the present invention is to provide a pressure relief valve, which facilitates adjustment of the injection valve opening pressure, and is capable of being manufactured at low cost.
Further, an object of the present invention is to provide a pressure relief valve, which simplifies the shape of the spring seat.
Further, an object of the present invention is to provide a pressure relief valve capable of guaranteeing the operational stability of the valve spring in the valve holder.
Further, an object of the present invention is to provide a pressure relief valve, which is capable of preventing hunting in a valve body, such as a ball valve, and, in addition, is capable of enhancing the wear resistance of a contact portion.
A first invention has been made, focusing on making the low-pressure portion side end portion of a valve holder a closed structure, and is a pressure relief valve, having a valve holder, which has a high-pressure portion side end portion facing the high-pressure portion side, and a low-pressure portion side end portion facing the low-pressure portion side; a valve spring, which is housed inside this valve holder; a spring seat on which this valve spring is seated; a valve seat, which is mounted to the above-mentioned valve holder; and a valve body, which, in accordance with the pressure of the fluid of the above-mentioned high-pressure portion side, is lifted from this valve seat against the biasing force of the above-mentioned valve spring, this pressure relief valve being characterized in that there is formed a closed end portion for making the above-mentioned low-pressure portion side end portion of the above-mentioned valve holder a closed state, and, in addition, the above-mentioned valve spring can be seated between the inner wall surface of this closed end portion and the above-mentioned spring seat.
The above-mentioned closed end portion can be made deformable towards the inside of the above-mentioned valve holder.
The above-mentioned valve seat can be press fitted to the above-mentioned valve holder, and, in addition, it is possible to provide a stopper step portion for determining a press fitting position between the above-mentioned valve seat and the above-mentioned valve holder.
In a pressure relief valve according to the first invention, because the low-pressure portion side end portion of the valve holder is constituted so as to be a closed structure, this closed structure differs from a sealing structure for sealing the inside of a valve holder using a sealing ball as in
Hozumi Etsuro
Kasahara Kazumasa
Kikuchi Hideya
Kushida Takeo
Yamazaki Akinori
Bosch Automotive Systems Corporation
Ostrolenk Faber Gerb & Soffen, LLP
Rivell John
LandOfFree
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