초록 ▼

A pressure compensated hydraulic valve (2) is provided with a housing (4) having a reciprocal spool (6) for communicating hydraulic fluid to work ports (8,10). Pressure compensating means (58) is provided in the same housing with the valve and senses work port pressure by hydraulic fluid flow throug

A pressure compensated hydraulic valve (2) is provided with a housing (4) having a reciprocal spool (6) for communicating hydraulic fluid to work ports (8,10). Pressure compensating means (58) is provided in the same housing with the valve and senses work port pressure by hydraulic fluid flow through the spool from the work port and creates a substantially fixed differential pressure across the spool by controlling the pressure after the flow has passed through the spool.

대표청구항 ▼

A closed center hydraulic control valve assembly comprised of a plurality of control valve sections joined in a bank and for use with a variable displacement pump having output and pressure sensing ports, each of said control valve sections having therein a valve spool movable to an operating positi

A closed center hydraulic control valve assembly comprised of a plurality of control valve sections joined in a bank and for use with a variable displacement pump having output and pressure sensing ports, each of said control valve sections having therein a valve spool movable to an operating position for selectively directing pressure fluid from a supply passage to one of a pair of workports via a feeder passage having upstream and downstream branches with a connecting passage therebetween and with said downstream feeder branch having a U-shaped bridge passage having a pair of legs selectively respectively communicable with said workports by said valve spool, the improvement which comprises: a check valve biased in one direction toward a position closing said connecting passage and adapted to be moved in the oposite direction to a position opening said connecting passage under force exerted on said check valve in said upstream feeder branch; metering means on said spool for establishing a predetermined pressure differential across said spool in said operating position; means for translating workport pressure into force on said check valve and also tending to move said check valve in said closing one direction whereby said check valve can act to hold a load in the absence of pressure in said upstream feeder branch; means in said housing to communicate workport pressure with said sensing input port of said variable displacment pump having said output port connected with said supply passage, whereby said check valve acts as a pressure compensating valve and moves back and forth to vary the degree of communication between said feeder branches in response to variations in the forces of opposing fluid pressures acting thereon, to thereby maintain said predetermined pressure differential across said spool and shuttle means operable to effect subjection of each said check valve to the highest pressure of any said workport in said bank, said shuttle means comprising a sensing shuttle passage in each said control section between the respective said bridge passage and a shuttle check valve, and a through shuttle passage between said shuttle check valve of its control section and the shuttle check valve of the next control section, such that if the workport pressure in said bridge passage is greater than the workport pressure in the bridge passage in the previous section, then said shuttle check valve in the present section closes the through shuttle passage of the previous section and opens the sensing shuttle passage of the present section to the through shuttle passage of the present section such that the workport pressure in the bridge passage of the present section is passed through the sensing shuttle passage of the present section to the next section, and such that if the workport pressure in the bridge passage of the present section is less than the workport pressure in the bridge passage of the previous section, then the shuttle check valve of the present section closes the sensing shuttle passage of the present section such that the workport pressure of the previous section flows through the shuttle passage of the previous section and into the through shuttle passage of the present section and into the next section, such that the highest workport pressure is communicated to said pump and to the other side of each of said pressure compensating check valves in said sections.