Fluid handling – Self-proportioning or correlating systems – Self-controlled branched flow systems
Reexamination Certificate
2000-03-20
2001-11-27
Hepperle, Stephen M. (Department: 3753)
Fluid handling
Self-proportioning or correlating systems
Self-controlled branched flow systems
C137S114000, C137S505130, C137S907000
Reexamination Certificate
active
06321772
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a vacuum pressure-adjusting apparatus capable of supplying an adjusted predetermined vacuum pressure to a fluid pressure-operated apparatus which is operated by the vacuum pressure.
2. Description of the Related Art
A process has been hitherto carried out, in which a workpiece is sucked and transported, for example, by using a suction means such as a suction pad in accordance with an action of the vacuum pressure. When the vacuum pressure is supplied from a vacuum pump to the suction pad, a vacuum pressure-adjusting apparatus such as a vacuum regulator is provided between the vacuum pump and the suction pad, for adjusting the vacuum pressure from the vacuum pump to have a predetermined value so that the vacuum pressure is supplied to the suction pad.
Such a vacuum regulator concerning the conventional technique is shown in
FIG. 4
(see Japanese Laid-Open Patent Publication No. 7-295655).
The vacuum regulator
1
comprises a housing
6
formed with a vacuum port
3
which is connected to a vacuum pressure supply source
2
such as a vacuum pump, and a pressure regulator port
5
which is connected to a vacuum pressure-operated apparatus
4
such as a suction pad.
A hole
7
, which extends in the axial direction, is formed at a central portion in the housing
6
. A valve stem
8
is provided slidably in the hole
7
. A valve plug
11
, which is urged by a spring force of a first compressive coil spring
9
to seat on a valve seat
10
, is coupled to the valve stem
8
. A seal member
12
, which is composed of an elastic member such as rubber to make abutment against the valve seat
10
, is secured to the valve plug
11
. In this arrangement, the valve plug
11
is urged by the spring force of the first compressive coil spring
9
so that the valve-closed state is always given. The seal member
12
, which is composed of the elastic member, is seated on the valve seat in a state of biting into the valve seat
10
which is composed of an annular projection (see FIG.
5
).
An atmospheric chamber
14
which communicates with the outside via a communication hole
13
, and a vacuum chamber
16
which communicates with the pressure regulator port
5
via a bypass hole
15
are formed and comparted by a diaphragm
17
in the housing
6
.
A communication port
19
, which is opened and closed by the valve stem
8
, is formed in an interlocking disk
18
which is displaceable integrally with the diaphragm
17
. A second compressive coil spring
20
, which has a spring force to urge the valve plug
11
in a direction to make separation from the valve seat
10
, is arranged at the inside of the housing
6
. The second compressive coil spring
20
is designed such that the spring force thereof is adjusted by a handle
21
.
In this arrangement, the vacuum pressure of the pressure regulator port
5
is set by the second compressive coil spring
20
. When the vacuum pressure is not more than a predetermined pressure, the atmospheric air is supplied via the communication port
19
to the pressure regulator port
5
.
However, the vacuum regulator
1
concerning the conventional technique described above involves the following inconvenience. That is, when the valve plug
11
is in the valve-closed state, the seal member
12
of the valve plug
11
is in the state of biting into the valve seat
10
by the aid of the spring force of the first compressive coil spring
9
. Therefore, even when the handle
21
is operated and rotated to finely adjust the predetermined vacuum pressure, the response sensitivity is blunt, because of the following reason.
That is, when a predetermined vacuum pressure is reset to another finely adjusted vacuum pressure, it is necessary that the valve plug
11
is reliably separated from the valve seat
10
to give the valve-open state, and the vacuum port
3
is communicated with the pressure regulator port
5
to change the vacuum pressure supplied from the pressure regulator port
5
. In order to give the valve-open state of the valve plug
11
, it is necessary that the valve plug
11
is firstly displaced slightly in an amount of the biting of the seal member
12
into the valve seat
10
, and then the seal member
12
of the valve plug
11
is separated from the valve seat
10
to form a predetermined clearance. However, in the case of the vacuum regulator
1
concerning the conventional technique, a so-called dead zone appears, in which the vacuum pressure is not changed even when the valve plug
11
is slightly displaced in the amount of the biting of the seal member
12
into the valve seat
10
. For this reason, it takes a long time until the vacuum pressure begins to change, and the response speed is slow.
Further, the vacuum regulator
1
concerning the conventional technique involves the following inconvenience. That is, when a predetermined vacuum pressure is finely adjusted, and it is reset to another vacuum pressure, then the setting accuracy of the reset vacuum pressure is inferior, and the setting operation is time-consuming and complicated, because the dead zone appears as described above.
SUMMARY OF THE INVENTION
A general object of the present invention is to provide a vacuum pressure-adjusting apparatus which makes it possible to improve the response sensitivity and the setting accuracy by decreasing the dead zone.
A principal object of the present invention is to provide a vacuum pressure-adjusting apparatus which makes it possible to conveniently perform the setting operation for the vacuum pressure when a predetermined vacuum pressure is finely adjusted, and it is reset to another vacuum pressure.
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.
REFERENCES:
patent: 3766933 (1973-10-01), Nicholson, Jr.
patent: 4291717 (1981-09-01), Orcutt
patent: 2109597 (1972-09-01), None
patent: 07-295655 A (1995-11-01), None
Iguma Naoki
Shirane Takashi
Uehara Teruo
Guss Paul A.
Hepperle Stephen M.
SMC Kabushiki Kaisha
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