Motors: expansible chamber type – Plural relatively movable or rigidly interconnected working... – With means to control the working fluid to one working...
Reexamination Certificate
2002-09-16
2004-04-06
Look, Edward K. (Department: 3745)
Motors: expansible chamber type
Plural relatively movable or rigidly interconnected working...
With means to control the working fluid to one working...
C091S525000
Reexamination Certificate
active
06715403
ABSTRACT:
TECHNICAL FIELD
This invention relates to a fluid control system for operating actuators. More particularly, the invention is directed to a fluid control system for operating multiple actuators in independent and regenerative function modes.
BACKGROUND
Some fluid control systems operate a double-acting actuator with a regeneration capability. The fluid control systems with this regeneration capability direct some of the fluid exhausted from a contracting chamber of a double-acting actuator to an expanding chamber of the actuator.
In the past, a regeneration valve is typically disposed between a main directional control valve and an actuator to provide a quick drop capability to the actuator driven in one direction by gravity loads. In such a configuration, however, an operator has little or no control over the amount of regenerated fluid recirculated from the contracting chamber to the expanding chamber.
A fluid control system with a relatively simple regeneration capability has been provided in association with a pump, a tank, and a double-acting actuator having a pair of actuating chambers. For example, U.S. Pat. No. 6,161,467 discloses a fluid control system having a regeneration capability. The system includes a pump, a tank, two double-acting actuators having actuating chambers, and a control valve. The control valve moves from a first position to a second position in a regeneration mode. This fluid control system, however, does not allow operation of the multiple actuators both regeneratively and independently. It is desirable to provide a fluid control system that provides accurate control of the actuators and has a compact size.
Accordingly, the present invention is directed to overcoming one or more of the problems as set forth above.
SUMMARY OF THE INVENTION
In one aspect of the invention, a fluid control system includes a reservoir, a pump in fluid communication with the reservoir, a first double-acting actuator having a first head end chamber and a first rod end chamber, a second double-acting actuator having a second head end chamber and a second rod end chamber. The first and second double-acting actuators are selectively fluidly connected via a conduit. A first independent metering valve is configured to selectively provide fluid flow to the first and second double-acting actuators, and a second independent metering valve is configured to selectively provide fluid flow to the first and second double-acting actuators. The fluid control system also includes a proportional valve attached to the conduit between the first double-acting actuator and the second double-acting actuator. The proportional valve is capable of operating the fluid control system in either an independent function mode or a regenerative function mode.
In another aspect of the invention, a method is provided to control fluid flow to and from first and second double-acting actuators in an independent function mode and a regenerative function mode. A first independent metering valve is provided having a first check valve in fluid communication with the first and second double-acting actuators. A second independent metering valve is also provided having a second check valve in fluid communication with the first and second double-acting actuators. A proportional valve is further provided in fluid communication with the first and second double-acting actuators. The proportional valve is operated to allow the first and second actuators to selectively operate in independent and regenerative function modes.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.
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Hajek, Jr. Thomas J.
Srikrishnan Rangamani
Tolappa Srikrishnan T.
Caterpillar Inc
Finnegan Henderson Farabow Garrett & Dunner
Leslie Michael
Look Edward K.
Srikrishnan Rangamani
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