Gas valve

Details Gas valve Gas valve

2002-06-11

2004-07-20

Chambers, A. Michael (Department: 3753)

Fluid handling

With casing, support, protector or static constructional...

Jacketed

C251S356000, C251S368000

Reexamination Certificate

active

06763849

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a gas valve, and more particularly to a gas valve having an annular seal surface for opening and closing a flow passage of gas.
DESCRIPTION OF THE RELATED ART
Conventionally, to use compressed natural gas (hereafter referred to as CNG) as fuel for an automobile engine, there is a CNG regulator having a constitution as shown in
FIG. 4
that decompresses the CNG in a gas cylinder loaded on the automobile into a predetermined pressure, as disclosed in JP-A-2000-249000.
A summary of the CNG regulator shown in
FIG. 4
will be described.
There is an intake
2
formed on a body
1
. The CNG flows into a chamber
8
through a filter
3
, a passage
4
, a valve portion
6
of a cut-off valve
5
, and a flow-in passage
7
. A housing
9
is contained in the chamber
8
, and a valve body
10
of a gas valve for pressure control is contained in the housing
9
being capable of rising and falling. Further, there is a port
11
formed in the housing
9
.
The valve body
10
is opposed to a seat
12
disposed on an upper portion of the chamber
8
being capable of coming in and out of contact with each other. When the valve body
10
moves downward apart from the seat
12
, the high-pressure CNG in the chamber
8
is supplied into a decompression chamber
14
through an annular clearance
13
. When the valve body
10
moves upward to contact with the seat
12
, the CNG in the chamber
8
is not supplied into the decompression chamber
14
.
A cover
15
is fixed on an upper portion of the body
1
, and a margin portion
16
a
of a diaphragm
16
lies between the body
1
and the cover
15
. The margin portion
16
a
is held by the body
1
and the cover
15
, and the diaphragm
16
serves as a partition between the decompression chamber
14
and an atmosphere chamber
17
. A central portion of the diaphragm
16
is held by a diaphragm holder
18
and a shell
19
. A lower portion of the diaphragm holder
18
is connected in a fitting state to an upper edge of the valve body
10
. The rising of the diaphragm
16
moves the valve body
10
upward to block up the seat portion
12
. The falling of the diaphragm
16
moves the valve body
10
downward to open the seat portion
12
.
Between the shell
19
and a regulating screw
20
provided in the cover
15
, a pressure control spring
21
is provided to force the diaphragm
16
downward. By a balance between the force of the pressure control spring
21
and the gas pressure of the CNG in the decompression chamber
14
, the diaphragm
16
is made to rise and fall, i.e., the valve body
10
is made to open and close, thereby keeping the gas pressure of the CNG in the decompression chamber
14
at a predetermined pressure.
The decompressed CNG in the decompression chamber
14
is supplied from an outlet
22
formed in the body
1
to the automobile engine.
In the CNG regulator having such a constitution as mentioned above, a seal surface
10
a
of the valve body
10
is formed of a metal surface, which is made merely by processing a metal of which the valve body
10
is made.
In the valves that control the passing and cut-off of the gas containing a large amount of water vapor such as the CNG, if an ambient temperature drops below the dew point after a system such as the regulator or the like has stopped, dew condensation causes water drops to deposit on the seal surface
10
a
of the valve body
10
as well as on every part.
When there are such water drops depositing, if the seal surface
10
a
of the valve body
10
has the processed metal surface, the water drops depositing on the seal surface
10
a
remain on it. When the ambient temperature becomes 0° C. or lower later, the depositing water drops freeze on the seal surface
10
a
, and the seal surface
10
a
is fixed to the seal
12
. In this case, it might not be possible to start operating next time.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to provide a gas valve for controlling the passing and cut-off of the gas that prevents the freezing and fixing on a seal surface and that prevents a system from being unable to operate.
To solve such problems, the present invention provides a gas valve including a valve body having an annular seal surface, of which seal surface an axis is disposed to extend in a vertical direction, and of which seal surface a diameter becomes larger toward a lower end thereof, wherein a liquid repellent film is provided on the seal surface of the valve body.
In the present invention, if there is gas that contains water vapor in a gas flow passage of an apparatus in which the valve is provided, when an ambient temperature drops below the dew point while the apparatus is stopped, the vapor is condensed to water drops on the seal surface of the valve body. However, the diameter of the seal surface of the valve body becomes larger downward and the seal surface has the liquid repellent film formed on it. Thus, the water drops on the seal surface made by the condensation flow downward by their own weight and do not remain on the seal surface. Therefore, even if the ambient temperature becomes 0° C. or lower later, the water drops do not freeze on the seal surface, and the seal surface and the seat will not be firmly fixed to each other because of the freezing. In this way, it is possible to prevent the valve body from being fixed and from not being able to operate at the time when the apparatus starts operating.
Further, according to the present invention, the liquid repellent film may be formed by being coated with a liquid repellent including a fluoroalkylsilane as a main component.
According to the present invention, a fluoroalkylsilane may be used as the liquid repellent. As this has a very high liquid repellent characteristic, it is highly effective in preventing the water drops from remaining on the seal surface.
Still further, according to the present invention, an annular groove portion may be provided lower than the seal surface of said valve body, and be formed annularly around an entire circumference of the valve body.
With this constitution, the water drops that have flown down from the seal surface, as described above, remain and freeze in the groove portion. Therefore, the water drops freeze in a place where they do not cause trouble for the valve operation, thereby preventing the freezing on the seal surface.
Furthermore, according to the present invention, the groove portion may be provided with a water retention member.
With this structure, the water drops that have flown down from the seal surface are retained in the water retention member provided in the groove portion. Therefore, the water is prevented from flowing into a sliding portion of the valve body positioned under the groove portion and from freezing in the sliding portion. It is thereby possible to prevent the valve body from not being able to operate.


REFERENCES:
patent: 3796228 (1974-03-01), Bedo et al.
patent: 4089882 (1978-05-01), Takamizawa et al.
patent: 4098295 (1978-07-01), Haytayan
patent: 5381819 (1995-01-01), Gotthelf
patent: 5746198 (1998-05-01), Taba et al.
patent: 5762102 (1998-06-01), Rimboym
patent: 5957119 (1999-09-01), Perry et al.
patent: 6176256 (2001-01-01), Nakajima et al.
patent: 6273130 (2001-08-01), Cossins
patent: 6328054 (2001-12-01), Martin et al.
patent: 6449603 (1989-03-01), None
patent: 6449604 (1989-03-01), None
patent: 03249314 (1991-11-01), None
patent: 2000 249000 (2000-09-01), None

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