Flow control valve

Details Flow control valve Flow control valve

1999-07-08

2001-03-13

Hepperle, Stephen M. (Department: 3753)

Fluid handling

Line condition change responsive valves

With separate connected fluid reactor surface

C137S495000, C137S510000

Reexamination Certificate

active

06199582

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a flow control valve for maintaining a constant flow rate of fluid (liquid or gas).
2. Description of the Related Art
The inventors of the present invention have disclosed, in Japanese Patent No. 2671183, a flow control valve employing diaphragms to secure a constant flow rate at the discharge (secondary) side of the valve irrespective of pressure variations at the inlet (primary) side thereof.
FIGS. 10 and 11
show this disclosure. The flow control valve
100
has a body
110
and a valve mechanism
120
. The body
110
defines a chamber
130
, which has an inlet
111
for receiving fluid to control, a valve seat
113
for passing the fluid, and an outlet
112
for discharging the fluid. The valve mechanism
120
has a valve plug
121
for opening and closing the valve seat
113
, a first diaphragm
122
arranged on the inlet side, and a second diaphragm
123
arranged on the outlet side. The first and second diaphragms
122
and
123
divide the chamber
130
into a first pressure chamber
131
, a valve chamber
135
, and a second pressure chamber
140
. A first pressurizing unit
151
is arranged in the first pressure chamber
131
and a second pressurizing unit
152
is arranged in the second pressure chamber
140
, to inwardly (toward the valve chamber
135
) apply constant pressure to the first and second diaphragms
122
and
123
. In this example, the first pressurizing unit
151
is a spring and the second pressurizing unit
152
is pressurized gas. The valve
100
also has an intake port
141
for receiving the pressurized gas and a discharge port
142
for discharging the same.
In the valve
100
, a pressure change at the inlet
111
works as a back pressure (outward pressure) on the first and second diaphragms
122
and
123
. The valve mechanism
120
moves to balance the back pressure with the inward pressure applied by the pressurizing units
151
and
152
. This results in moving the valve plug
121
to change an aperture between the valve plug
121
and the valve seat
113
, thereby controlling the flow rate of the fluid controlled by the valve
100
.
The valve mechanism
120
with the integrated diaphragms
122
and
123
provides a great advantage of quickly responding to instantaneous or pulsating pressure changes in the fluid controlled by the valve
100
. This kind of pressure changes cannot be coped with by conventional valves having mechanical or electrical means. Further advantages of the valve
100
are the simple mechanism and structure and easy maintenance of the valve.
The valve
100
, however, has presented new problems due to the integrated first and second diaphragms
122
and
123
.
When the outlet
112
is clogged or closed, the second diaphragm
123
receives a large back pressure to apply large load on the valve mechanism
120
. This large load may damage a joint (fastened with threaded parts) between the first and second diaphragms
122
and
123
. When the back pressure at the outlet
112
moves the valve plug
121
to close the valve seat
113
, large friction occurs between them due to the back pressure acting on the second diaphragm
123
and the pressure applied by the first pressuring unit
151
on the first diaphragm
122
. This may break the valve plug
121
and valve seat
113
to produce dust particles.
These problems may lead to a failure of the valve
100
and deteriorate the function, durability, and reliability thereof. The dust particles, if produced, are hazardous to ultrapure water or chemical fluid for which such flow control valves are widely used.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a flow control valve having a novel structure to prevent the deterioration and damage of the valve or the production of dust particles in the valve even if an outlet (secondary side) of the valve shows a load increase.
Another object of the present invention is to provide a flow control valve capable of closing the secondary side thereof, to develop new application fields for the valve.
Still another object of the present invention is to provide a flow control valve having simple and inexpensive mechanical and electrical structures including a diaphragm mechanism to instantaneously respond to momentary or pulsating load changes.
In order to accomplish the objects, a first aspect of the present invention provides a flow control valve (
10
) having a body (
11
) and a valve mechanism (
40
). The body defines a chamber (
20
). The chamber involves an inlet (
12
) for receiving fluid to control, a valve seat (
16
) for passing the fluid, and an outlet (
15
) for discharging the fluid. The valve mechanism consists of a valve plug (
41
) for opening and closing the valve seat, a first diaphragm (
50
) arranged in the vicinity of the inlet, and a second diaphragm (
60
) arranged in the vicinity of the outlet. Each of the diaphragms is in the chamber and has a periphery fixed to the body. The diaphragms divide the chamber into a first pressure chamber (
21
) outside the first diaphragm, a valve chamber (
25
) between the diaphragms, and a second pressure chamber (
30
) outside the second diaphragm. The valve chamber includes the inlet, valve seat, and outlet. The first and second pressure chambers have a first pressurizing unit (M
1
) and second pressurizing unit (M
2
), respectively, to always apply constant pressure to the valve chamber through the first and second diaphragms. The first diaphragm (
50
) is provided with an integrated first member (
51
) having the valve plug (
41
), and the second diaphragm (
60
) is provided with an integrated second member (
61
) that removably engages with the first member.
A second aspect of the present invention provides the first and second members with a conical projection (
52
) and a conical recess (
62
), respectively, so that the projection and recess may removably engage with each other.
A third aspect of the present invention forms the pressurizing unit provided for the first pressure chamber with a spring (S
1
).
A fourth aspect of the present invention forms the pressurizing unit provided for the second pressure chamber with pressurized gas (A
1
).
A fifth aspect of the present invention arranges a check valve (
35
) at an intake port (
31
) that introduces the pressurized gas into the second pressure chamber.
A sixth aspect of the present invention arranges a throttle mechanism (
37
) in a supply circuit (
36
) that supplies the pressurized gas to the second pressure chamber.
A seventh aspect of the present invention arranges a throttle mechanism (
39
) in a discharge circuit (
38
) that discharges the pressurized gas from the second pressure chamber.
An eighth aspect of the present invention provides the second diaphragm with a suck-back mechanism (
70
).
A ninth aspect of the present invention forms the suck-back mechanism with a spring (S
2
) that pushes the second diaphragm away from the valve chamber.


REFERENCES:
patent: 1743127 (1930-01-01), Fuller
patent: 2160849 (1939-06-01), Fausek, et al.
patent: 2220496 (1940-11-01), Ringelstetter
patent: 550466 (1957-12-01), None
patent: 0 783 145 A1 (1997-07-01), None
Patent Abstract of Japan: “Differential Pressure Driven Three Way Type Valve ”, Inventor: Irisa Hirokazu, Mar. 19, 1986.

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