Valves and valve actuation – Fluid actuated or retarded – Piston type expansible chamber reciprocating valve actuator
Reexamination Certificate
2000-12-20
2002-05-21
Derakshani, Philippe (Department: 3754)
Valves and valve actuation
Fluid actuated or retarded
Piston type expansible chamber reciprocating valve actuator
C251S028000, C251S357000
Reexamination Certificate
active
06390442
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a two-port valve for allowing and intercepting passage of fluid such as air, oil, water, and steam.
PRIOR ART
There is a known pilot-type two-port valve in which a pilot valve is switched to supply or discharge pressure fluid to and from a pressure operating chamber on one face side of a pressure-receiving body such as a piston and a diaphragm to move up and down the pressure-receiving body and a valve member connected to the pressure-receiving body through a valve stem to open and close a valve seat, thereby connecting and separating an input port and an output port for the pressure fluid to and from each other by opening and closing of the valve seat.
A known pilot-type two-port valve
100
shown in
FIG. 4
as an example includes a main valve
101
having an input chamber
103
into which pressure fluid is introduced from an input port, an output port
104
, a valve seat
105
in a flow path connecting the ports, and a valve member
106
for opening and closing the valve seat
105
and a pilot valve
102
. In the main valve
101
, the valve seat
105
is opened and closed by moving the valve member
106
up and down through a valve stem
107
. A pressure-receiving body (a diaphragm in this example)
108
is secured to the valve stem
107
and the valve stem
107
is constantly pushed in a valve-closing direction by a return spring
109
. The pressure-receiving body
108
is moved up and down by supplying and discharging the pressure fluid to and from the pressure operating chamber
110
by the pilot valve
102
.
In the above known pilot-type two-port valve
100
, a first stepped portion
114
and a second stepped portion
115
formed of shoulder portions and small-diameter portions extending in an axial direction are formed at a lower portion of the valve stem
107
, an external thread is formed at an outer periphery of the small-diameter portion of the second stepped portion
115
, the valve member
106
and a receiving plate
116
are respectively fitted over the small-diameter portions of the first stepped portion
114
and the second stepped portion
115
, the valve member
106
is pushed against the shoulder portion of the first stepped portion
114
through the receiving plate
116
to mount the valve member
106
to the valve stem
107
by screwing a nut
117
over the small-diameter portion of the second stepped portion
115
.
However, in this type of pilot-type two-port valve
100
, because the valve member
106
is pushed against the valve stem
107
through the receiving plate
116
by screwing the nut
117
in mounting the valve member
106
to the valve stem
107
, there are the following problems (1) to (4).
A two-port valve that is not the pilot type essentially has the similar problems.
(1) Because the valve member is fixed to the valve stem through the nut, it is difficult to obtain a satisfactory degree of parallelization of the valve member and the valve seat and airtightness is poor.
(2) Because it is necessary to screw the nut while fixing the valve stem, assembly is not easy and replacement of the valve member is not easy either.
(3) Because it is necessary to take measures against loosening of the nut and an assembly property and reliability are poor.
(4) It is necessary to subject the valve stem to thread cutting and rotation preventing processing and cost increases.
DISCLOSURE OF THE INVENTION
It is an object of the present invention to provide a two-port valve in which a deviation of a degree of parallelization of a valve member and a valve seat can be corrected automatically, which has excellent airtightness, in which assembly and replacement of the valve member are easy, which has excellent assembly property and reliability, and in which cost can be reduced.
To achieve the above object, a two-port valve of the invention comprises a valve body including an input port and an output port for pressure fluid, a valve seat in a flow path connecting the ports, and a valve member for opening and closing the valve seat, wherein a shaft for driving the valve member for opening and closing has at its tip end portion a shoulder portion, a small-diameter portion extending in an axial direction from the shoulder portion, and a groove portion which is formed in a vicinity of a tip end portion of the small-diameter portion and into which a snap ring is mounted, the valve member has a through hole into which the small-diameter portion of the shaft is inserted and an annular stepped portion formed by increasing a diameter of a portion of the through hole, and the stepped portion being mounted with a sealant for providing sealing between the shaft and the valve member, and the valve member is locked while being pushed against the shoulder portion by the snap ring mounted into the groove portion through the plate.
In the two-port valve of the invention, it is preferable that the stepped portion formed in the through hole of the valve member is formed by increasing the diameter of the through hole on a tip end side of the shaft and that the valve member is pushed against the shoulder portion through the sealant mounted to the stepped portion by the plate or that the shoulder portion of the shaft is tapered and a portion of the valve member pushed against the shoulder portion has a taper that is substantially similar to a taper of the shoulder portion.
The two-port valve may be a pilot-type two-port valve for driving a valve member with pilot fluid pressure, the valve member is connected to a piston driven for opening and closing of the valve seat through a shaft, and a pressure operating chamber to and from which the pilot fluid pressure is supplied and discharged is formed on one side face of the piston.
In mounting of the valve member and the shaft to each other in the two-port valve, the valve member is fitted over the small-diameter portion formed on the shaft, the sealant is mounted to the stepped portion of the valve member, and the plate fitted over the small-diameter portion pushes the valve member through the sealant to resiliently push the valve member against the shoulder portion of the shaft. In this state, a diameter of the snap ring is increased, the snap ring is fitted over the small-diameter portion, and the diameter of the snap ring is reduced in a position of the groove portion formed at the small-diameter portion to mount the snap ring into the groove portion.
Therefore, the valve member is locked by the snap ring mounted into the groove portion of the shaft in a state in which the plate presses the sealant against resilience of the sealant and pushes the valve member against the shoulder portion of the shaft.
By carrying out the operations in a reverse order, the valve member can be detached from the shaft.
As described above, because the valve member is not fixed to the shaft but is locked resiliently by the snap ring through the plate in the two-port valve of the invention, the valve member can be seated along the valve seat, a deviation of a degree of parallelization of the valve member can be corrected automatically, and the shaft is unnecessary to be subjected to thread cutting and rotation preventing processing of a nut.
The plate is locked by the snap ring, which provides measures against loosening. Because sealing is provided between the shaft and the valve member by the sealant mounted to the stepped portion of the valve member, sealing is reliable.
REFERENCES:
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patent: 2687273 (1954-08-01), Starkey
patent: 2720219 (1955-10-01), Grove et al.
patent: 2731036 (1956-01-01), Hughes
patent: 2886283 (1959-05-01), Natho
patent: 2985424 (1961-05-01), Anderson et al.
patent: 4237920 (1980-12-01), Norman
patent: 4257442 (1981-03-01), Claycomb
patent: 4355784 (1982-10-01), Cain
patent: 4634099 (1987-01-01), Danko et al.
patent: 5007328 (1991-04-01), Otteman
patent: 5131627 (1992-07-01), Kolenc
U.S. application No. 09/737,582, filed Dec. 18, 2000, pending.
U.S. application No. 09/739,205, filed Dec. 19, 2000, pending.
U.S. application No. 09/739,780, filed Dec. 20,
Sakurai Toyonobu
Suzuki Hiroaki
Tokuda Tetsuro
Bonderer D. Austin
Derakshani Philippe
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
SMC Corporation
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