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Hydraulic pump and valve

  • US 4,285,641 A
  • Filed: 07/27/1979
  • Issued: 08/25/1981
  • Est. Priority Date: 07/27/1979
  • Status: Expired due to Term
First Claim
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1. A hydraulic pump and valve unit comprisinga unitary block having a hydraulic fluid reservoir appended to one side of the block;

  • a first cylindrical bore drilled into said block extending inwardly from one end wall thereof;

    a first flow passage bored into said block from said hydraulic fluid reservoir, said first flow passage communicating from the inner end of said first cylindrical bore to said hydraulic fluid reservoir;

    a pump piston adapted for reciprocal movement in said first cylindrical bore so as to form a pump chamber between the piston and the inner end of said first cylindrical bore;

    means for moving said piston in its reciprocal movement;

    first check valve means which allows hydraulic fluid to flow from the reservoir to the pump chamber but substantially prevents backflow of the hydraulic fluid from the pump chamber to the reservoir;

    a second cylindrical bore drilled into said block extending inwardly from a second end wall so as to be generally perpendicular to said first cylindrical bore, with the inner end of the second cylindrical bore being milled so as to be flat;

    a third cylindrical bore drilled into said block extending from the flat, milled, inner end of said second cylindrical bore toward the first cylindrical bore, said third cylindrical bore having a diameter no greater than one-half the diameter of the second cylindrical bore, with the cylindrical axis of said third cylindrical bore being offset from the cylindrical axis of said second cylindrical bore;

    a second flow passage bored inwardly from the inner end of said third cylindrical bore so as to connect said third cylindrical bore with said first cylindrical bore;

    a third flow passage associated with said piston and adapted to connect said second flow passage to said pump chamber;

    second check valve means which allows hydraulic fluid to flow from said pump chamber through said third flow passage to said second flow passage, but substantially prevents backflow of the hydraulic fluid from said second flow passage to said pump chamber;

    a cylindrical thrust seal having a substantially axial borehole extending therethrough and being slidably mounted in said third cylindrical bore, said seal including sealing means between the outer cylindrical wall of the thrust seal and the cylindrical wall of said third cylindrical bore;

    a fourth flow passage bored inwardly from the inner end of said second cylindrical bore so as to connect said second cylindrical bore with said reservoir;

    a cylindrically-shaped valve spool rotatably mounted in said second cylindrical bore, said valve spool having an essentially flat inner end adapted to abut the flat end of said second cylindrical bore;

    means for rotating the valve spool;

    fifth and sixth flow passages in said valve spool having mutually respective ports disposed on the flat, inner end of said valve spool so that the ports can be brought into mutually alternating register with said third cylindrical bore and said fourth flow passage, respectively, in the inner end of said second cylindrical opening by rotation of said valve spool, said fifth and sixth flow passages extending through said valve spool from said ports in the end of the valve spool to mutually respective openings in the cylindrical side of said valve spool, so that said fifth and sixth flow passages extend solely between the cylindrical side and the inner, flat end of said valve spool, with the outer end of the valve spool being externally open to the exterior of the unitary block and connected to the means for rotating the valve spool and;

    seventh and eighth flow passages bored inwardly from the side of said block so as to have respective spaced openings into said second cylindrical bore which are adapted to register with the respective openings in said valve spool, said seventh and eighth flow passages being adapted to direct the outflow and return of hydraulic fluid from and to the pump and valve unit.

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