Load referenced pressure reducing valve

A system for supplying hydraulic fluid to a system load to meet rapidly changing load demands thereat, said system comprising:

• a source of pressurized hydraulic fluid;
• at least one hydraulic cylinder having a piston slidably disposed therein defining first and second chambers in said cylinder, said piston operable in first and second directions by fluid pressure in said first and second chambers, respectively, said cylinder subjected to variable loading in at least said first direction of operation;
• first and second means for supplying hydraulic fluid to said first and second chambers, respectively, at least said first means for supplying including:
• a load-referenced pressure reducing valve which provides load-referenced pressure reduction independently of flow therethrough, said valve comprising:
• a valve body having a cartridge bore and a plurality of ports, said plurality of ports including at least an inlet port, an outlet port, a tank port, and a load sensing port;
• a cartridge, at least a portion of which is disposed in said cartridge bore, comprising:
• a cartridge body defining:
• a plurality of apertures, ones of said plurality of apertures generally alignable with ones of said ports, said apertures including at least one inlet aperture, at least one outlet aperture, at least one tank aperture and at least one load sensing aperture;
• a spring chamber:
• and
• a spool bore;
• a spring disposed in said spring chamber;
• and
• a spool slidably disposed in said spool bore and engaging said spring, said spool further including:
• a first portion adapted to receive and convey fluid from said inlet aperture to said outlet aperture, said first portion slidably positionable to vary the flow of said fluid between said inlet and outlet apertures;
• a second portion adapted to receive and convey fluid from said load sensing aperture to said spring chamber;
• and
• a third portion adapted to receive fluid leaking from said first portion inside said cartridge body and convey said fluid to said tank aperture;
• means for preventing backflow to said load-referenced pressure reducing valve, said means for preventing backflow disposed downstream from said outlet port of said load-referenced pressure reducing valve;
• at least one first means for impeding the flow of said fluid to said cylinder, said first means for impeding flow disposed downstream from said means for preventing backflow;
• and
• at least one load sensing line communicating fluid pressure from said first chamber of said cylinder to said load sensing port of said load-referenced pressure reducing valve;
• and
• first and second means for returning fluid from said first and second chambers, respectively;
• whereby said at least one load-referenced pressure reducing valve rapidly adjusts in position in response to fluid pressure variations in said first chamber.

A pressure regulating system for regulating fluid pressure in an existing hydraulic system having an existing source of pressurized hydraulic fluid, at least one existing system load, at least one means for supplying fluid to said at least one existing system load, and at least one means for returning fluid from said at least one existing system load, wherein at least one said existing system load is subjected to rapidly changing load demands, said pressure regulating system comprising:

• at least one load-reference pressure reducing valve for pressure reduction independent of flow therethrough, each said load-referenced valve comprising:
• a valve body having a cartridge bore and a plurality of ports, said plurality of ports including at least an inlet port to receive hydraulic fluid from said existing source of pressurized fluid, an outlet port to convey fluid at a reduced pressure to said at least one existing system load subjected to rapidly changing load demands, a load sensing port to receive and convey fluid and load pressure from said existing system load, and a tank port to convey away fluid leaking from said inlet port;
• a cartridge, at least a portion of which is disposed in said cartridge bore, comprising:
• a cartridge body defining:
• a plurality of apertures, ones of said plurality of apertures generally aligned with ones of said ports, said apertures including at least one inlet aperture, at least one outlet aperture, at least one tank aperture and at least one load sensing aperture;
• a spring chamber:
• and
• a spool bore;
• a spring disposed in said spring chamber;
• and
• a spool slidably disposed in said spool bore and engaging said spring, said spool further including:
• first means to receive and convey fluid from said inlet aperture to said outlet aperture, said means to receive and convey slidably positionable to vary the flow of said fluid between said inlet and outlet apertures;
• second means to receive and convey fluid and pressure from said load sensing aperture to said spring chamber;
• and
• third means to receive and convey fluid leaking from said first portion inside said cartridge body to said tank aperture;
• whereby said existing hydraulic system provides rapid adjustments in pressure in response to rapidly changing load demands in said at least one existing system load.