Valves and valve actuation – Fluid actuated or retarded – Piston type expansible chamber reciprocating valve actuator
Reexamination Certificate
1997-09-30
2001-01-09
Walczak, David J. (Department: 3751)
Valves and valve actuation
Fluid actuated or retarded
Piston type expansible chamber reciprocating valve actuator
C251S058000
Reexamination Certificate
active
06170797
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a rotary actuator operated by an air pressure and used to control a valve, for example.
FIGS. 11
to
15
c
show a conventional rotary actuator. A cylinder body
11
is produced by cutting an extruded material
1
(see FIG.
14
c
), formed by extruding aluminum or other similar material, into a predetermined length and forming various bores in the cut extruded material
1
. As shown in FIGS.
14
c,
14
d
and
11
, a vertical section of the extruded material
1
has a circular bore (cylinder bore
11
a
) in the center. Squarish thick-walled portions
12
to
15
project from the extruded material
1
upwardly, downwardly, leftwardly and rightwardly, respectively, as viewed in the vertical section (in
FIG. 12
, the thick-walled portions
12
to
15
project upwardly, downwardly, forwardly and backwardly, respectively). A thick-walled portion
2
having an approximately triangular sectional configuration is formed between each pair of adjacent thick-walled portions
12
to
15
. That is, the cylinder body
11
has a total of four thick-walled portions
2
. Each thick-walled portion
2
has an insertion bore
3
extending therethrough longitudinally (i.e. the direction of the center axis of the cylinder bore
11
a
). As shown in
FIGS. 11
,
13
and
14
d,
a first end plate
17
and a second end plate
18
, which are octagonal, are brought into contact with both ends of the cylinder body
11
. The first end plate
17
and the second end plate
18
have insertion bores
19
formed in coaxial relation to the insertion bores
3
of the cylinder body
11
. Four long bolts
5
are inserted into the insertion bores
19
of the first and second end plates
17
and
18
and the corresponding insertion bores
3
of the cylinder body
11
, and nuts
6
are screwed onto the long bolts
5
, respectively, thereby connecting together the cylinder body
11
and the first and second end plates
17
and
18
.
An upper bearing portion
11
b
is formed in an approximately central portion of the upwardly projecting thick-walled portion
12
of the cylinder body
11
. A lower bearing portion
11
c
is formed in an approximately central portion of the downwardly projecting thick-walled portion
13
of the cylinder body
11
. An upper rotating shaft
24
and a lower rotating shaft
25
are rotatably fitted into and supported by the upper bearing portion
11
b
and the lower bearing portion
11
c,
respectively. The upper rotating shaft
24
has a prismatic portion at the lower end thereof. The prismatic portion of the upper rotating shaft
24
is fitted into a square hole provided in the upper end of a connecting shaft
21
. The lower rotating shaft
25
has a prismatic portion at the upper end thereof. The prismatic portion of the lower rotating shaft
25
is fitted into a square hole provided in the lower end of the connecting shaft
21
. If desired, a cap that indicates an angular position of the connecting shaft
21
is fitted to the upper end of the upper rotating shaft
24
that projects upwardly from the cylinder body
11
. The lower end portion of the lower rotating shaft
25
projects downwardly from the cylinder body
11
. A piston
20
is slidably fitted in the cylinder bore
11
a.
The piston
20
has a bottom portion
20
a
having a circular sectional configuration and adapted to receive an air pressure. The piston
20
further has a first projecting portion
20
b
and a second projecting portion
20
c,
which are integral with the bottom portion
20
a.
The upper and lower end portions of the piston
20
, exclusive of the bottom portion
20
a,
are horizontally cut. The piston
20
has a vertical groove
20
d
vertically extending therethrough. The piston
20
further has longitudinal horizontal grooves communicated with the vertical groove
20
d.
Thus, the first projecting portion
20
b
and the second projecting portion
20
c
are formed as shown in
FIGS. 11 and 13
.
The second projecting portion
20
c
is provided with an insertion bore vertically extending therethrough. A pin
23
is inserted into the insertion bore. The connecting shaft
21
is located in the vertical groove
20
d
between the first projecting portion
20
b
and the second projecting portion
20
c.
A yoke
22
is inserted into a horizontal bore
21
a
provided in the connecting shaft
21
. One end of the yoke
22
is pivotably connected to the pin
23
. The other end of the yoke
22
is movably inserted into the horizontal groove of the first projecting portion
20
b.
As the piston
20
moves, the pin
23
also moves simultaneously, and the one end of the yoke
22
moves together with the pin
23
. Consequently, the yoke
22
pivots to rotate about the vertical axis of the connecting shaft
21
, causing the connecting shaft
21
to rotate. As the connecting shaft
21
rotates, the upper rotating shaft
24
and the lower rotating shaft
25
rotate simultaneously. The first end plate
17
has a first stopper
27
screwed into a threaded bore provided therein. Similarly, the second end plate
18
has a second stopper
28
screwed into a threaded bore provided therein. The first and second stoppers
27
and
28
have respective nuts screwed thereon so as to be fixed in predetermined positions, respectively. When moved back and forth, the piston
20
comes in contact with the distal ends of the first and second stoppers
27
and
28
. By changing the fixed positions of the first and second stoppers
27
and
28
, the stroke of the piston
20
is adjusted, and the rotation angle of the connecting shaft
21
is regulated.
As shown in
FIG. 13
, a pressure reducing valve
30
is connected to the outer side of the first end plate
17
, and a pressure gauge
31
is provided in connection with the pressure reducing valve
30
. As will be clear from FIG.
14
a,
a solenoid-operated switching valve
33
is connected through a sub-plate
32
to the center of the front (left side) surface of the leftwardly projecting thick-walled portion
14
of the cylinder body
11
. Further, a first speed controller
34
and a second speed controller
35
are connected to the left and right end portions, respectively, of the leftwardly projecting thick-walled portion
14
. An inlet port of the pressure reducing valve
30
is communicated with an air pressure source (not shown) through piping. An outlet port of the pressure reducing valve
30
is communicated with an inlet port of the solenoid-operated switching valve
33
through piping
7
a.
An A-port the solenoid-operated switching valve
33
is communicated with one port of the first speed controller
34
through piping
7
b.
A B-port of the solenoid-operated switching valve
33
is communicated with one port of the second speed controller
35
through piping
7
c.
The other port of the first speed controller
34
is communicated with a first cylinder chamber
38
of the cylinder body
11
through a communicating passage
8
a
(see FIG.
13
). The other port of the second speed controller
35
is communicated with a second cylinder chamber
39
of the cylinder body
11
through a communicating passage
8
b
(see FIG.
13
). An open valve
36
for short circuiting is communicated between the piping
7
b
and the piping
7
c.
By opening the open valve
36
, the first cylinder chamber
38
and the second cylinder chamber
39
are communicated with each other through the first speed controller
34
and the second speed controller
35
. Consequently, the connecting shaft
21
can be rotated by a manual operation. It should be noted that, as shown in FIG.
14
b,
the open valve
36
enables the passages to be communicated with or cut off from each other by rotating a ball valve element
36
a
with a lever
36
b.
FIG. 11
shows a conventional rotary actuator
9
as used to open and close a valve (e.g. a butterfly valve or a ball valve)
40
. The lower end of the rotary actuator
9
and an upper flange
40
b
of the valve
40
are connected by a connecting member
41
, bolts
42
and nuts
43
. The lower rotating shaft
25
has
Inoue Keisuke
Kimura Yasuhito
Baker & Botts L.L.P.
SMC Corporation
Walczak David J.
LandOfFree
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