Fluid handling – Self-proportioning or correlating systems – Self-proportioning flow systems
Reexamination Certificate
1999-06-30
2001-09-18
Hepperle, Stephen M. (Department: 3753)
Fluid handling
Self-proportioning or correlating systems
Self-proportioning flow systems
C137S269000, C091S515000
Reexamination Certificate
active
06289917
ABSTRACT:
FIELD OF THE INVENTION
The present invention is directed to a proportional flow divider valve. More particularly, the present invention is directed to a proportional flow divider valve used in control flow and free flow operational modes.
BACKGROUND OF THE INVENTION
Flow divider valves are used in hydraulics systems, such as hydraulic systems for lifting dump truck beds. With a dump truck bed accurate regulation of hydraulic fluid flow to hydraulic cylinders is necessary as the bed is raised with a heavy load, and is frequently not necessary when the load has been dumped and the bed is returning to its down position. Highly restrictive, relatively small, metering openings through which hydraulic fluid flows to lift the bed may unduly slow lowering of the bed. Consequently, it is desirable to by-pass the restrictive openings. In the past, this has been done with a separate return valve which of course increases expense and manufacturing time, as well as increasing parts inventory.
Proportional flow divider valves have been developed with check valve capability built into the valve body of the proportional flow divider valve; however, a valve body having both capabilities cannot be used for situations where it is only desirable to have the proportional flow divider feature without a free flow capability. Consequently, when stocking valves with both control flow and free flow capabilities, two types of valve bodies need to be stocked.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a proportional flow divider valve having a valve body which can be used as a flow divider valve only or as a flow divider valve with a return check valve to permit free flow of returning fluid through the valve body.
In view of this feature and other features, the present invention is directed to a proportional flow divider valve comprising a valve body having an inlet port and a plurality of work ports, wherein the inlet port is adapted for connection to a source of pressurized fluid and the work ports are adapted to connect to a hydraulic working device. The valve body includes a flow divider therein for dividing fluid flow entering the valve body through the inlet port into a plurality of controlled flows, each of which exit the valve body through a separate work port to power the working device. A return check valve, integral with the flow divider, blocks flow of fluid through the flow divider as fluid returns through the work ports into the valve body and out of the inlet port.
In a more specific aspect, the flow divider is configured as a spool within the valve body, the spool having a lateral inlet passage and a pair of opposed axially extending outlet passages in communication with the inlet passage. The return check valve does not block the inlet passage when fluid is flowing into the inlet port and blocks the inlet passage when fluid is flowing into the work ports.
In a more specific aspect, the return check valve is configured as a sleeve assembly biased by a spring to normally keep the inlet passage through the spool open when the valve is in a controlled flow mode, the bias of the spring being overcome by fluid pressure against the sleeve assembly exerted by fluid returning from the work ports when the valve is in a free flow mode.
REFERENCES:
patent: 2242002 (1941-05-01), Klein
patent: 4121601 (1978-10-01), Presley
patent: 4261381 (1981-04-01), Geiling
patent: 4465089 (1984-08-01), Inhofer
Hepperle Stephen M.
Millen White Zelano & Branigan P.C.
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