Cylinder assembly

Details Cylinder assembly Cylinder assembly

2003-01-29

2004-07-13

Lazo, Thomas E. (Department: 3745)

Motors: expansible chamber type

With correlated control of motive fluid and locking means

Sequential operation of locking means and motive fluid control

C092S027000

Reexamination Certificate

active

06761103

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a cylinder assembly suitably used, for example, for a work support of a machine tool.
2. Explanation of Related Art
For instance, a conventional work support cylinder assembly comprises only one cylinder for working, as disclosed in Japanese Patent Public Disclosure No. 10-146733 proposed by the present inventors (or U.S. Pat. No. 5,979,267 which corresponds to the Japanese publication).
An example of the cylinder assembly of this kind that the present inventors know comprises two cylinders of a working cylinder and an advancing and retreating cylinder, and it operates as follows.
When performing a locking operation, first, an advancing and retreating piston of the advancing and retreating cylinder ascends to bring a support rod into contact with a workpiece by an urging force of an advancing spring. Thereafter, the working cylinder holds and fixes the support rod at a raised position. Further, when making a releasing operation, first, the support rod is cancelled from the condition held and fixed by the working cylinder. Then the advancing and retreating piston descends, thereby enabling the support rod to move down against the urging force of the advancing spring.
The conventional technique which comprises the two cylinders had a problem that when cancelling the support rod from the held and fixed condition, the support rod protrudes up the workpiece by resorting to the urging force of the advancing spring.
SUMMARY OF THE INVENTION
The present invention has an object to provide a cylinder assembly which can solve such a problem as mentioned above.
In order to accomplish the above object, the present invention has constructed a cylinder assembly in the following manner, for example, as shown in
FIG. 1
,
FIGS. 2A
to
2
F and
FIGS. 3A
to
3
F or in
FIGS. 4
to
6
.
The cylinder assembly comprises a first working cylinder
20
and an advancing and retreating cylinder
32
. The first cylinder
20
performs a locking operation when a gas pressure of an actuation chamber
23
has exceeded a first set pressure (P1) and can make a releasing operation when the gas pressure of the actuation chamber
23
has decreased to a second set pressure (P2) lower than the first set pressure (P1). The second cylinder
32
comprises a second piston
35
fitted into a second cylinder bore
33
, an inlet chamber
41
formed between a first end wall
40
of the second cylinder bore
33
and the second piston
35
, which pressurized gas is supplied to and discharged from, an outlet chamber
45
formed between a second end wall
44
of the second cylinder bore
33
and the second piston
35
, and a return means
46
which retracts the second piston
35
to the first end wall
40
. The actuation chamber
23
communicates with the outside air through the outlet chamber
45
. A flow resistance applying means (K) is provided in a route between the actuation chamber
23
and the outside air. A changeover means
61
is provided for communicating the actuation chamber
23
with the inlet chamber
41
or the outlet chamber
45
. The changeover means
61
communicates the actuation chamber
23
with the outlet chamber
45
during a term from the beginning to the end of an advancing movement of the second piston
35
. On the other hand, it communicates the actuation chamber
23
with the inlet chamber
41
at the terminal of the advancing movement of the second piston
35
.
The above-mentioned invention operates in the following way, for example, as shown in
FIGS. 2A
to
2
F and in
FIGS. 3A
to
3
F.
When performing the locking operation, pressurized gas such as compressed air is supplied to the inlet chamber
41
. Then while the inlet chamber
41
has its pressure (M) increased as indicated by a full line in
FIG. 2F
, the actuation chamber
23
has its pressure (N) increased in delay from the increase of the pressure (M) of the inlet chamber
41
by an action of the changeover means
61
, as shown by a broken line in FIG.
2
F. Therefore, first, as shown in
FIGS. 2A
to
2
D, the pressure of the inlet chamber
41
raises the second piston
35
(and an operation member
51
connected to the second piston
35
) and then the pressure (N) of the actuation chamber
23
becomes higher than the set pressure (P1), thereby advancing a first piston
22
of the first cylinder
20
to a locking side as shown in FIG.
2
E.
Further, when making the releasing operation, the pressurized gas in the inlet chamber
41
is discharged to an exterior area. Then while the pressure (M) of the inlet chamber
41
decreases as indicated by a full line in
FIG. 3F
, the pressure (N) of the actuation chamber
23
decreases in delay from the decrease of the pressure (M) of the inlet chamber
41
owing to an action of the flow resistance applying means (K), as shown by a broken line in FIG.
3
F. Therefore, first, as shown in
FIG. 3A
to
FIG. 3D
, the return means
46
lowers the second piston
35
(and the operation member
51
) and then the pressure (N) of the actuation chamber
23
becomes lower than the second set pressure (P2), thereby retracting the first piston
22
to a releasing side as shown in FIG.
3
E.
In consequence, the present invention offers the following advantage.
When locking, the first cylinder can perform the locking operation after the second piston of the second advancing and retreating cylinder has been advanced. When releasing, the first cylinder can make the releasing operation after the second piston has been retreated.
Accordingly, for example, in the case where the present invention is applied to a work support, at the above releasing time, it is possible to prevent the support rod from protruding up the workpiece by resorting to an advancing means such as the above-mentioned advancing spring.
The present invention includes the following cylinder assembly.
The second cylinder bore
33
has a peripheral surface opened to provide a communication hole
62
which communicates the actuation chamber
23
with an interior area of the second cylinder bore
33
. An opening portion of the communication hole
62
and an outer peripheral surface of the second piston
35
constitute the changeover means
61
. This invention can form the changeover means
61
into a simple structure with preciseness, which leads to a possibility of putting a reliable cylinder assembly into practice at a low cost.
The present invention includes the following cylinder assembly, for example, as shown in
FIGS. 4
to
6
.
A sealing member
65
is interposed between the peripheral surface of the second cylinder bore
33
and the outer peripheral surface of the second piston
35
. This invention enables the sealing member to assuredly prevent the pressurized gas which has been supplied to the inlet chamber from leaking into the outlet chamber. Thus when supplying the pressurized gas, the pressurized gas can be inhibited from leaking from the outlet chamber to the outside air, which results in reducing the consumption amount of the pressurized gas. Besides, it is possible to prevent the leaked pressurized gas from letting constituent members of the cylinder assembly make some misoperation when supplying the pressurized gas.
The present invention includes the following cylinder assembly, for example, as shown in
FIGS. 4
to
6
.
The sealing member
65
is attached to the outer peripheral surface of the second piston
35
and forms one part of the changeover means
61
. This invention can provide a changeover means which makes a sure operation and has a simple structure.
The present invention includes the following cylinder assembly, for example, as shown in
FIGS. 4
to
6
.
A restricting passage
66
is provided in the communication hole
62
and forms at least one part of the flow resistance applying means (K). This invention can form the flow resistance applying means into a simple structure with preciseness, which leads to the possibility of putting a reliable cylinder assembly into practice at a low cost.
The present invention includes the follo

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