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Pump arrangement driven by compressed-air

  • US 4,971,531 A
  • Filed: 10/26/1989
  • Issued: 11/20/1990
  • Est. Priority Date: 10/28/1988
  • Status: Expired due to Fees
First Claim
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1. A compressed air driven pump arrangement comprising a compressed air piston motor and an hydraulic piston pump, said pump arrangement comprising first and second end wall parts and a cylinder housing therebetween, means to supply compressed air to said compressed air piston motor and means to vent said air from said compressed air piston motor, said compressed air piston motor comprising a low pressure piston movable in said cylinder housing between said first and second end wall parts in a power stroke in one direction and in a return stroke in the other direction and means housing substantially all other portions of said compressed air piston motor in said first end wall part, means housing substantially all of said hydraulic piston pump in said second end wall part, said low pressure piston comprising a first side and a second side, said compressed air piston motor comprising a working chamber defined by said first side of said low pressure piston and said first end wall part, said hydraulic piston pump comprising hydraulic piston means cooperable with hydraulic chamber means formed in said second end wall part, said low pressure piston and said hydraulic piston means being so arranged that said hydraulic piston means abuts said second side of said low pressure piston, said compressed air piston motor further comprising a pilot piston and a control piston, means to join said control piston to said low pressure piston at said first side thereof, said first end wall part being formed with a pilot cylinder in which said pilot piston is fitted for movement between a first position and a second position, means to fit said control piston for motion within said pilot piston, said pump arrangement further comprising spring means arranged to effect said return stroke of said low pressure piston and said hydraulic piston means, said compressed air piston motor comprising a pilot piston working chamber defined by said pilot piston and portions of said first end wall part;

  • said hydraulic piston means, said spring means, and said low pressure, pilot and control pistons being so arranged that said control piston causes said pilot piston to move from its first to its second position and said spring means causes motion of said pilot piston from said second to said first position by abutment of said hydraulic piston means against said low pressure piston and said pilot piston;

    said pilot piston being arranged to supply compressed air from said supply means into and to prevent venting of said air out of said compressed air piston motor low pressure piston working chamber in said first position of said pilot piston and to permit the venting via said vent means of said compressed air out of and to prevent supply of compressed air into said compressed air piston motor low pressure piston working chamber in said second position of said pilot piston, said control piston causing the movement of said pilot piston from said first position to said second position by permitting compressed air from said supply means to enter said pilot piston working chamber, and said control piston further being arranged to permit said low pressure piston to move said pilot piston from said second position to said first position by preventing compressed air from said supply means from entering said pilot piston working chamber and to vent said air from said pilot piston working chamber to said vent means.

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