Information
-
Patent Grant
-
6314863
-
Patent Number
6,314,863
-
Date Filed
Wednesday, June 30, 199925 years ago
-
Date Issued
Tuesday, November 13, 200122 years ago
-
Inventors
-
Original Assignees
-
Examiners
- Look; Edward K.
- Leslie; Michael
Agents
- Oblon, Spivak, McClelland, Maier & Neustadt, P.C.
-
CPC
-
US Classifications
Field of Search
-
International Classifications
-
Abstract
An end-closing structure for a rodless cylinder comprises an end cap and a sleeve. The end cap is fitted and inserted into a bore of a cylinder tube. Further, the sleeve is fitted and inserted into a through hole of the end cap through a hole of the cylinder tube. By means of inserting a spring pin into a hole through a hole, the bore is closed such that ends of the end cap and the cylinder tube are positioned substantially in the same plane surface.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an end-closing structure for an actuator for transferring workpieces.
2. Description of the Related Art
In recent years, various types of actuators have been used as means for transferring workpieces in a factory or the like.
The actuators convert a power generated by air or oil pressure into a power for the use of mechanical work by a cylinder tube and a piston received into a cylinder chamber of the cylinder tube for being displaced axially along the cylinder chamber, wherein the cylinder tube and the piston are closely fitted together. One type of the above actuators is a rodded cylinder, wherein a piston rod is exposed from a rod cover connected to an end of the cylinder tube. Another type of the above actuators is a rodless cylinder, wherein the space needed for attaching the actuator is reduced.
For example, the above rodless cylinder is constructed such that a driving power can be taken out from a slit of the cylinder tube through a yoke or the like. The structure and the operation thereof will be briefly explained below.
A rodless cylinder shown in
FIG. 3
includes a bore
2
extending longitudinally in a cylinder tube
1
of a cylinder body. Each end of the cylinder tube
1
is closed in an airtight manner by a cover
4
which serves to close the end of the cylinder tube
1
having a shape of a rectangular parallelopiped. A fluid input/output port
3
a is defined in the cover
4
. A cylindrical piston
5
is provided in the cylinder tube
1
. Pressure receiving surfaces
5
a
,
5
b
are formed at both ends of the piston
5
. A yoke
6
protruding from a slit (not shown) is provided on the upper portion of the piston
5
. Further, a movable body
7
, which engages with the yoke
6
, is provided such that the movable body
7
is displaced in unison with the yoke
6
. The slit of the cylinder tube
1
is covered with a seal band
8
a
, and the yoke
6
is covered with a dust seal band
8
b.
In the rodless cylinder constructed as above, the piston
5
reciprocates along the bore
2
by, for example, pressurized fluid such as compressed air supplied from the fluid input/output port
3
a
. In this case, the yoke
6
and the movable body
7
are displaced in unison with the piston
5
such that a workplace (not shown) placed on the movable body
7
is transferred to a predetermined position.
The structure of closing the end of the rodless cylinder by the cover
4
will be further explained.
As shown in
FIG. 4
, the cover
4
comprises a rectangular parallelopiped member
4
a
and a cylindrical member
4
b
. The cylindrical member
4
b
has a step which extends into an unillustrated hole of the rectangular parallelopiped member
4
a
. Thus, the rectangular parallelopiped member
4
a
and the cylindrical member
4
b
are connected. The fluid input/output port
3
a
is defined in the center of an end surface of the rectangular parallelopiped member
4
a
. The fluid input/output port
3
a
communicates with a hole
3
c
of the cylindrical member
4
b
through a passage
3
b
defined in the rectangular parallelopiped member
4
a
. Further, through holes
4
c
are defined in the rectangular parallelopiped member
4
a
for attaching the rodless cylinder to another member. The cylindrical member
4
b
is inserted into the bore
2
defined in the cylinder tube
1
by four bolts
9
which are screwed into holes defined adjacent to four corners of the rectangular parallelopiped member
4
a
, respectively. In this way, the cover
4
is fixed to the end of the cylinder tube
1
, thereby closing the bore
2
.
The cover
4
of the conventional rodless cylinder (actuator) adopts a construction, wherein the rectangular parallelopiped member
4
a
and the cylindrical member
4
b
in different shapes are connected, and a plurality of bolts
9
are needed for fixing the cover
4
to the end of the cylinder tube
1
. Accordingly, both of manufacturing and attaching operations thereof are laborious, and, the manufacturing cost of the actuator becomes rather high. Further, since the cover
4
is fixed to the cylinder tube
1
such that the cover
4
protrudes outwardly from the end of the cylinder tube
1
, the overall longitudinal dimension of the apparatus is equal to a sum of dimensions of the cylinder tube
1
and the covers
4
. Accordingly, an actuator as a finished product tends to be unduly elongated.
SUMMARY OF THE INVENTION
It is a general object of the present invention to provide an end-closing structure for an actuator which makes it possible to reduce the longitudinal dimension of the actuator so as to minimize the size thereof.
A major object of the present invention is to provide an end-closing structure for an actuator which makes it possible to simplify the assembling operation of an actuator to reduce the manufacturing cost thereof by providing a closing member for closing an end of an actuator body and an engaging member for fixing the closing member.
The above and other objects, features, and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings in which a preferred embodiment of the present invention is shown by way of illustrative example.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
is a schematic perspective view of a rodless cylinder, wherein the end-closing structure for an actuator according to the present embodiment is adopted;
FIG. 2
is an exploded perspective view for an end portion of the rodless cylinder, wherein the end-closing structure for an actuator according to the present embodiment is adopted;
FIG. 3
is a longitudinal cross sectional view, with partial cut out, illustrating a conventional rodless cylinder, wherein a cover for closing an end of a cylinder is attached; and
FIG. 4
is a schematic exploded perspective view for illustrating the end-closing structure for a cylinder, wherein a cover according to the conventional rodless cylinder is used.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Preferred embodiment of an end-closing structure for an actuator according to the present invention will be explained in detail hereinbelow with reference to the accompanying drawings.
A rodless cylinder
10
according to the end-closing structure for the actuator according to the present invention is shown in FIG.
1
. With respect to the rodless cylinder
10
, a bore (not shown) is defined in an elongated cylinder tube
11
, and a piston (not shown) is provided in the bore. The piston is displaceable in unison with a movable body
12
provided on an upper surface of the cylinder tube
11
by a yoke (not shown) or the like.
An end of the cylinder tube
11
is closed by an end cap (closing member)
14
. The end cap
14
is fixed by engagement to a sleeve (engaging member
18
). A fluid input/output port
16
is defined at an end of the sleeve
18
. The ends of the end cap
14
and the sleeve
18
are substantially in the same plane surface with the end of the cylinder tube
11
. Further, a belt clamp
20
is provided on an upper part of the end cap
14
. The belt clamp
20
supports a dust seal band
22
extending longitudinally on an upper part of the cylinder tube
11
.
As shown in
FIG. 2
, the cylinder tube
11
has a bore (chamber)
24
extending longitudinally and having an elliptical cross section. The bore
24
communicates with the outside through a slit
26
defined on an upper surface of the cylinder tube
11
. Recesses
28
are defined longitudinally on both sides sandwiching the slit
26
on the upper surface of the cylinder tube
11
.
A hole
29
for inserting and fitting the sleeve
18
is defined at one side surface of the end of the cylinder tube
11
. The hole
29
communicates with the bore
24
. Further, a semi-circular cut out
31
which communicates with the bore
24
and which has a shape corresponding to the belt clamp
20
is defined at the central end of the upper surface of the cylinder tube
11
. A hole
33
having a step is defined perpendicularly to an axial direction of the hole
29
on a side opposite to the side at which the hole
29
is defined. Further, holes
37
are defined at both sides such that the cut out
31
is defined therebetween. A spring pin (pin member)
39
is provided to function as a rotation-prevention for the sleeve
18
by means of insertion into the hole
33
. In this embodiment, since a plurality of conventional bolts for attaching a cover to the cylinder tube
11
are not required, a tap treatment on one side surface of the end of the cylinder tube
11
for making screw holes for inserting bolts thereinto becomes unnecessary. Accordingly, the manufacturing process thereof is simplified.
Next, the end cap
14
and the sleeve
18
or the like according to the closing structure of the present invention will be explained in detail hereinbelow.
The end cap
14
has an elliptically cylindrical outer configuration. A hole (a second hole)
30
for communication with the bore
24
is defined in the center of an elliptical surface of the end cap
14
. A through hole (a first hole)
32
having a step is perpendicularly defined for communication with the hole
30
. Further, a circumferential step
34
is formed around an outer circumferential edge on one end surface side where the hole
30
is defined. A seal member
35
having a shape of a ring is attached to the circumferential step
34
. The seal member
35
functions for closing the end of the cylinder tube
11
in an airtight manner. On the other end surface side of the end cap
14
, two holes
36
are defined. In this case, the outer configuration of the end cap
14
basically corresponds to the cross sectional configuration of the bore
24
of the cylinder tube
11
. Therefore, the outer configuration of the end cap
14
should not be limited to have an elliptical cross section.
The sleeve
18
comprises a cylindrical member having a step. A hole (communicating hole)
38
having substantially the same diameter as that of the hole
30
is defined at a longitudinally central position of a cylindrical wall surface of the sleeve
18
. The hole
38
extends in a direction perpendicularly to an axial direction of the sleeve
18
and communicates with the fluid input/output port
16
through a fluid passage
41
. The fluid passage
41
ends at a portion
18
a
. The portion
18
a
is closed by a solid portion
18
b
. The sleeve
18
may be constructed to define a through hole extending along an axial direction of the sleeve
18
such that one end of the through hole functions as the fluid input/output port
16
and the other end thereof is closed by an unillustrated cover plug. A hole
40
opening upwardly is defined at the solid portion
18
b
. A circulating groove
42
is defined at a position spaced from the hole
40
of the solid portion
18
b
. A ring-shaped seal member
43
is attached to the circulating groove
42
. Further, a ring-shaped seal member
45
is attached through a circulating groove
44
to a position axially spaced by a predetermined distance from the seal member
43
. These seal members
43
and
45
are used for sealing a fluid passage defined between the fluid input/output port
16
and the hole
30
from outside in an airtight manner by means of insertion of the sleeve
18
into the through hole
32
of the end cap
14
. Due to the annular step formed between the portion
18
a
and the solid portion
18
b
of the sleeve
18
, insertion of the sleeve
18
into the through hole
32
of the end cap
14
becomes easier. Further, the seal member
43
can be prevented from being detached at the time of insertion of the sleeve
18
.
Further, the belt clamp
20
to be placed on an upper side of the end cap
14
comprises a thin-walled member in a semicircular shape. A hole
46
having a rectangular cross section and two stripes of grooves
48
are defined at the top portion of the circumferential side surface of the belt clamp
20
. The grooves
48
opening downwardly are defined with an intermediary wall portion lying therebetween. Two holes
50
communicating with the grooves
48
through the hole
46
, and two through holes
52
for attachment are defined in the belt clamp
20
, respectively.
Further, as shown in
FIGS. 1 and 2
, at both opposite sides of cylinder tube
11
, two stripes of grooves
62
,
64
for attaching sensors are defined to extend substantially in parallel with each other along an axial direction. A sensor for detecting the position of a piston (not shown) is fastened to each of the grooves
62
,
64
for attaching a sensor.
Next, with respect to the end-closing structure for the actuator according to the present invention, a method for attaching each member to the cylinder tube
11
will be explained below.
Firstly, the end cap
14
to which the seal member
35
is attached is inserted into the bore
24
of the cylinder tube
11
, directing a side on which the hole
30
is defined. In this case, the end cap
14
is received completely in the cylinder tube
11
such that the end of the end cap
14
and the end of the cylinder tube
11
are positioned substantially in the same plane surface (see FIG.
1
).
Next, the sleeve
18
to which the seal members
43
and
45
are attached is inserted through a hole
29
of the cylinder tube
11
and into the through hole
32
of the end cap
14
, directing a side of the solid portion
18
b
to the hole
29
. In this case, the sleeve
18
is received in the cylinder tube
11
completely such that the end of the sleeve
18
and a side surface of the cylinder tube
11
are positioned substantially in the same plane surface (see FIG.
1
).
In this way, the end cap
14
, the sleeve
18
and the cylinder tube
11
are fitted together. In this case, the bore
24
of the cylinder tube
11
is sealed in an airtight manner by the three seal members
35
,
43
and
45
.
Next, a spring pin
39
is inserted into the hole
33
of the cylinder tube
11
and then into the hole
40
of the sleeve
18
. In this way, the cylinder tube
11
, sleeve
18
and the end cap
14
are engaged together.
In this case, the spring pin
39
not only reliably makes the sleeve
18
engage with the cylinder tube
11
but also functions as a rotation-prevention to prevent the sleeve
18
from rotating. As a means of ensuring the latter function, instead of the spring pin
39
, for example, an engaging member (not shown) such as a screw may be provided. Alternatively, the cross sectional shape of the sleeve
18
and the hole
29
corresponding thereto may be polygonal. Further, the spring pin
39
also functions for preventing the sleeve
18
from being detached from the cylinder tube
11
.
In attaching the cylinder tube
11
to the movable body
12
, the belt clamp
20
is positioned at the cut out portion
31
. The end of seal belt (not shown) for sealing the slit
26
of the cylinder tube
11
, which was already explained as the conventional technique, is inserted into the grooves
48
of the belt clamp
20
. Also, the end of the dust seal band
22
is inserted into the hole
46
of the belt clamp
20
. Then, a screw member (not shown) is inserted through the hole
50
of the belt clamp
20
for fastening. Accordingly, each end of the seal belt and the dust seal band
22
is fixed by engagement by the belt clamp
20
. Further, screw members (not shown) are screwed into the attachment holes
52
of the belt clamp
20
and then into the holes
36
of the end cap
14
, respectively. Thus, the belt clamp
20
is fixed to the end cap
14
.
As described above, the end cap
14
and the sleeve
18
constituting the end-closing structure for the actuator according to the present embodiment are fitted and inserted into the cylinder tube
11
such that they are basically assembled together. Further, the reliable engagement of these members and the rotation-prevention of the sleeve
18
can be achieved by only a single spring pin
39
. Accordingly, attaching and disassembling operations for the end-closing structure are simply performed in a short time. Further, since the end-closing structure for the actuator is constituted by a few members having relatively simple configurations, it can be manufactured at a reduced cost with a single material in line with, so called, “the inverse manufacturing system”. Further, main members according to the end-closing structure do not require the fixing bolts
9
of the cover
4
unlike the embodiment of the conventional technique. In the present embodiment, since the attachment holes
37
of the cylinder tube
11
are used to substitute for the conventional holes
4
c
for attaching a main body, spaces for receiving bolts are not required. Accordingly, whole length of the end cap
14
itself is reduced. Further, since the end cap
14
is received in the cylinder tube
11
substantially completely, the longitudinal dimension of the rodless cylinder
10
can be reduced. Furthermore, since the longitudinal dimension along the bore
24
of the end-closing structure received in the cylinder tube
11
is small, a movable range of the piston in the bore
24
is not reduced in comparison with the conventional technique.
In using the rodless cylinder
10
, a fluid pressure-supplying source for air or the like is connected to communicate with the fluid input/output port
16
of the sleeve
18
. Under the fluid pressure, as explained in the embodiment of the conventional technique, by pressing the first or the second pressure-receiving surface of the piston, movable body is displaced in unison with the piston.
The end-closing structure for the actuator according to the present embodiment should not be limited for the use of a rodless cylinder. Rather, it can be used for the most actuators including the rodless cylinder. Further, it is used, for example, in the case for closing an end of a pressure container in an airtight manner or in a liquid-tight manner.
As explained above, according to the end-closing structure of the present invention, manufacturing processes and attaching operations of respective members for constructing the closing structure are simplified. Accordingly, manufacturing cost of an actuator can be reduced. Further, the size of the actuator can be minimized by reducing the longitudinal dimension thereof.
According to the end-closing structure for an actuator of the present invention, manufacturing processes and attaching operations of an end cap and a sleeve are easy. Further, manufacturing cost of a rodless cylinder can be reduced and respective members can be fabricated with a single material.
Further, according to the end-closing structure of the present invention, the size of an actuator can be minimized by reducing the vertical dimension thereof.
Claims
- 1. An end-closing structure for an actuator having an actuator body in which a chamber is defined and a piston which is displaceable under an operation of pressurized fluid supplied to said chamber, said structure comprising:a closing member which is fitted and inserted into an opening defined at an end of said actuator body for closing said opening; an engaging member which engages to fix said closing member to said actuator body such that said end of said actuator body and an end of said closing member are positioned substantially in the same plane surface, said engaging member having a fluid input/output port defined therein for communication with said chamber through a fluid passage; and rotation-preventing means for preventing said engaging member from rotating with respect to said closing member, wherein said rotation-preventing means comprises a pin member which passes through said engaging member in a substantially perpendicular direction to an axial direction of said engaging member, said pin member being fixed by engagement with a hole defined in said actuator body so as to prevent said engaging member from rotating.
- 2. An end-closing structure for an actuator according to claim 1, wherein said actuator comprises a rodless cylinder, said closing member comprising an end cap for closing an opening defined at an end of a cylinder tube, and said engaging member comprising a sleeve for fixing said end cap by engagement to said cylinder tube,a hole is defined in said end cap for insertion of said sleeve, and a fluid passage is defined in said sleeve for communication between said fluid input/output port and said chamber.
- 3. An end-closing structure for an actuator according to claim 2, wherein said hole defined in said cylinder tube is positioned to be offset in a substantially perpendicular direction to an axial direction of said cylinder tube, said pin member being inserted into a hole defined in a solid portion of said sleeve, thereby preventing said sleeve from rotating.
- 4. An end-closing structure for an actuator according to claim 3, wherein said hole defined in said cylinder tube is positioned between a side of said cylinder tube at which grooves for attaching sensors are defined and said chamber defined in said cylinder tube.
- 5. An end-closing structure for an actuator according to claim 2, wherein a first hole into which said sleeve is inserted and a second hole which communicates with said chamber are defined in said end cap, and a communication hole is defined in said sleeve for communication between said second hole of said end cap and said fluid input/output port.
- 6. An end-closing structure for an actuator according to claim 2, wherein said closing member is formed to have a oval-shape in cross section corresponding to said opening of said chamber.
- 7. An end-closing structure for an actuator having an actuator body in which a chamber is defined and a piston which is displaceable under an operation of pressurized fluid supplied to said chamber, said structure comprising:a closing member which is fitted and inserted into an opening defined at an end of said actuator body for closing said opening; and an engaging member which engages to fix said closing member to said actuator body such that said end of said actuator body and an end of said closing member are positioned substantially in the same plane surface, said engaging member having a fluid input/output port defined therein for communication with said chamber through a fluid passage, wherein said actuator comprises a rodless cylinder, said closing member comprising an end cap for closing an opening defined at an end of a cylinder tube, and said engaging member comprising a sleeve for fixing said end cap by engagement to said cylinder tube, a hole is defined in said end cap for insertion of said sleeve, and a fluid passage is defined in said sleeve for communication between said fluid input/output port and said chamber, and wherein said sleeve is formed to have a cylindrical configuration having an annular step in an intermediary section along longitudinal direction thereof, said hole in which said sleeve is inserted has a shape corresponding to the shape of said sleeve.
Priority Claims (1)
Number |
Date |
Country |
Kind |
10-186620 |
Jul 1998 |
JP |
|
US Referenced Citations (4)
Foreign Referenced Citations (3)
Number |
Date |
Country |
91 04 747 |
Sep 1992 |
DE |
43 34 424 |
Apr 1994 |
DE |
0 662 568 |
Jul 1995 |
EP |