Motors: expansible chamber type – With motive fluid valve – Relatively movable inlet and exhaust valves for single...
Reexamination Certificate
1999-06-17
2002-03-12
Look, Edward K. (Department: 3745)
Motors: expansible chamber type
With motive fluid valve
Relatively movable inlet and exhaust valves for single...
C091S464000
Reexamination Certificate
active
06354185
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a fluid control module that controls the flow of fluid to a device such as a hydraulic actuator.
2. Background Information
There are many types of machines that incorporate hydraulically-driven actuators which lift or move an object. The actuator can be integrated into a hydraulic system which has a high pressure supply line, a low pressure drain line and a control valve that controls the flow of hydraulic fluid between the actuator, the supply line and the drain.
FIG. 1
shows an actuator or double-acting hydraulic cylinder
1
which has a piston
2
that separates a first cylinder chamber
3
from a second cylinder chamber
4
. The piston
2
can move in either one of two directions, depending upon whether pressurized fluid is provided to the first cylinder chamber
3
or the second cylinder chamber
4
. As an alternative embodiment, the actuator may include a return spring (not shown) within the first cylinder chamber
3
which moves the piston in an outward direction when the second cylinder chamber is coupled to the drain line of the system.
The actuator
1
may be controlled by a control valve
5
. The control valve
5
typically contains a single three-way or four way spool valve (not shown) that can couple the cylinder chambers
3
and
4
to either a supply line
6
or a drain line
7
. The control valve
5
can be actuated into either one of two states. In one state, the control valve
5
couples the first cylinder chamber
3
to the drain line
7
and allows pressurized fluid to flow into the second cylinder chamber
4
to hydraulically move the piston
2
. In the other state, the valve
5
couples the second cylinder chamber
4
to the drain line
7
and allows pressurized fluid to flow into the first chamber
3
to hydraulically move the piston
2
in the opposite direction.
A control valve with a single spool only has two states. When the first cylinder chamber
3
is coupled to the supply line
6
, the second cylinder chamber
4
is always coupled to the drain line
7
. Likewise, when the second cylinder chamber
4
is coupled to the supply line
6
, the first cylinder chamber
3
is always coupled to the drain line
7
. It would be desirable to provide a control module that can provide more than two states. For example, it may be desirable to provide pressurized fluid to both cylinder chambers
3
and
4
to hold the position of the piston
2
.
SUMMARY OF THE INVENTION
One embodiment of the present invention is a fluid control module that can control the flow of fluid between a rail line, a drain line, a first cylinder line and a second cylinder line. The module includes a plurality of fluid-driven valves that can couple the cylinder lines to the rail and drain lines. Each fluid-driven valve is controlled by a control valve. The module may be actuated into at least one a plurality of different states.
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“Application of Unified Predictive Control to On/Off Control of Hydraulic System Driven by Fast-Switching Solenoid Valves”, Jeronymo et al., JSME International Journal, Series C, vol. 39, No. 3, pp. 515-520, 1996.
“Programmable Electrohydraulic Valve”, Book et al., SAE Paper Offer 99F-10, 1998.
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Blakely , Sokoloff, Taylor & Zafman LLP
Lazo Thomas E.
Look Edward K.
Sturman Industries, Inc.
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