Motors: expansible chamber type – Moving cylinder
Reexamination Certificate
2002-09-12
2004-08-24
Lazo, Thomas E. (Department: 3745)
Motors: expansible chamber type
Moving cylinder
C091S265000, C091S36300A
Reexamination Certificate
active
06779432
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a servo circuit for use with an air pressure actuator.
2. Description of the Related Art
As an air pressure actuator, there has been one which was suggested by the inventors of the present invention and is shown in FIG.
1
. Referring to
FIG. 1
, such an air pressure actuator
10
comprises a guide shaft
11
extending in one axial direction with both ends thereof fixed on a pair of support members
15
, and a slider
12
movable along the guide shaft
11
. In fact, the slider
12
is a cylindrical hollow body so formed that it can cover up a part of the guide shaft
11
, corresponding to a predetermined length thereof. In this way, an internal space is formed between the inner surface of the slider
12
and the outer periphery surface of the guide shaft
11
. Practically, such an internal space is used as a pressure chamber. In more detail, such an internal space serving as a pressure chamber has been divided (in its axial direction) into two cylinder chambers
16
a
and
16
b
by virtue of a partition wall
13
fixed on the guide shaft
11
. The slider
12
is slidable over the outer periphery surface of the partition wall
13
. At both ends of the slider
12
and with the cylinder chambers
16
a
,
16
b
are connected intake/exhaust systems
17
a
,
17
b
for introducing a compressed air into the cylinder chambers and for discharging the same therefrom. The intake/exhaust systems
17
a
,
17
b
are respectively equipped with servo valves
18
a
,
18
b
so as to form desired servo systems. These servo valves
18
a
,
18
b
are all connected to a compressed air supply source
100
.
For example, when the servo valve
18
a
is actuated to supply a compressed air, while the servo value
18
b
is actuated to discharge an amount of used air into the surrounding atmosphere, the partition wall
13
will be caused to act as a pressure receiving plate and the slider
12
will be moved to the left direction shown in FIG.
1
. In this way, by controlling the opening degree of the servo valves
18
a
and
18
b
, it is allowed to move the slider
12
to any desired position along the guide shaft
11
.
The air pressure actuator
10
is provided with a position detector, thereby forming a position feed back control system.
However, as will be described later in the present specification, in an arrangement where each of the intake/exhaust system is connected with only one servo valve (as shown in FIG.
1
), the speed resolving power of the air pressure actuator has been found deteriorated.
SUMMARY OF THE INVENTION
Accordingly, it Is an object of the present invention to improve the response and the speed control performance of a servo circuit which is for use with an air pressure actuator.
The servo circuit according to the present invention can be used in an air pressure actuator which has a partition wall provided on one of a slider and a guide shaft to form pressure chambers between the outer surface of the guide shaft and the internal surface of the slider, and to define these pressure chambers into two cylinder chambers arranged side by side in the axial direction.
According to an aspect of the present invention, intake/exhaust systems are connected with the two cylinder chambers for supplying a compressed air into the cylinder chambers or discharging the same therefrom. A plurality of servo valves having different maximum opening degrees are respectively connected with the intake/exhaust systems. The servo circuit further includes a position detector for detecting the position of the slider. Moreover, the servo circuit includes a control device for receiving the detection results of the position detector and a position instruction value, so as to perform a selection among a plurality of servo valves in accordance with an acceleration or deceleration zone and a constant speed zone of the slider, and to control an opening degree of a selected servo valve.
REFERENCES:
patent: 3757645 (1973-09-01), Roch
patent: 6523451 (2003-02-01), Liao et al.
patent: 05321904 (1993-12-01), None
patent: 07310562 (1995-11-01), None
patent: 09196004 (1997-07-01), None
Arent & Fox PLLC
Lazo Thomas E.
Sumitomo Heavy Industrie's, Ltd.
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