Piston pump with self-lubricating pistons

Claim 2

In a pumping mechanism having a housing, an internal oil reservoir therein filled with lubricant, at least one reciprocating piston in a stationary cylindrical bore, and means in said reservoir for reciprocAting said piston, the combination comprising: said cylindrical bore having a first end in said reservoir, a first portion extending to an annular chamber meeting said cylindrical bore at a shoulder, with a longitudinally extending passage extending outside said bore adjacent to said shoulder to said first end, and a second smaller-diameter portion beyond said annular chamber terminating at a second end, said piston having a first end in said reservoir and a first portion having a diameter just enough smaller than said first portion of said cylindrical bore to enable passage of oil therebetween during reciprocation, said piston having a second end beyond said annular chamber and within said second bore portion at all times and a second portion smaller in diameter than said first piston portion extending from said second piston end and meeting said first piston portion at a rim always lying within said first portion of said cylindrical bore, an O-ring in said annular chamber and movable against and away from said shoulder and in sealing relation with said second portion of said piston, thereby having a position closing said passage and a position opening said passage, sealing means sealing between said second bore portion and said second portion of said piston, and, pumping mechanism in said housing beyond said second end of said piston and actuated by the suction of said second portion of said piston in said second bore portion, said sealing means sealing off the fluid being pumped from said lubricant, while said O-ring acts as a valve opening and closing the passage between said groove and said cylindrical bore as the piston reciprocates, thereby lubricating said cylindrical bore and said piston.

Claim 3

The combination of claim 1 wherein said second piston portion is about 0.010 inch smaller in diameter than said first piston portion.

Claim 4

The combination of claim 2 wherein said diameter of said first piston portion is about 0.0015 to 0.0025 inch less than that of said cylindrical bore.

Claim 5

The combination of claim 1 wherein there is an enlarged annular recess in said second bore portion and said sealing means comprises an elastomeric sealing ring in said annular recess and a back-up ring in said annular recess between said sealing ring and said bearing member.

Claim 6

In a pumping mechanism having a housing, an oil reservoir therein filled with lubricant, at least one reciprocating piston in a stationary cylindrical bore, means in said reservoir for reciprocating said piston, the combination comprising: an enlarged annular recess in said bore, an elastomeric sealing ring of circular cross-section in said annular recess sealing between said bore and said piston and having a cross-sectional diameter slightly larger than the radial width of said recess, a non-elastomeric back-up ring in said annular recess next to said sealing ring having substantially the same crosssection radial width as said recess, said recess being longer in its axial extent than the combined axial extent of said backup ring and said cross-sectional diameter of said sealing ring, said two rings being the only members in said recess, said back-up ring being a combination of glass fibers, bronze, and tetrafluoroethylene, each ingredient being present in an amount of at least 15 percent of the total, and pumping mechanism in said housing beyond said piston and communicating with said bore and actuated by the alternating suction and pressure provided by reciprocation of said piston, said sealing ring sealing off the fluid being pumped from said lubricant.

Claim 7

In a pumping mechanism having a housing, an oil reservoir therein filled with lubricant, at least one reciprocating piston in a stationary cylindrical bore, means in said reservoir for reciprocating said piston, the combination comprising: an enlarged annular recess in said bore, an elastomeric sealing ring of circular cross-section in said annular recess sealing between said bore and said piston and having a cross-sectional diameter slightly larger than the radial width of said recess, a non-elastomeric back-up ring in said annular recess next to said sealing ring having substantially the same crosssection radial width as said recess, said recess being longer in its axial extent than the combined axial extent of said backup ring and said cross-sectional diameter of said sealing ring, said two rings being the only members in said recess, said back-up ring being a combination of glass fibers, bronze, and tetrafluoroethylene, each ingredient being present in an amount of at least 15 percent of the total, and pumping mechanism in said housing beyond said piston and communicating with said bore and actuated by the alternating suction and pressure provided by reciprocation of said piston, said sealing ring sealing off the fluid being pumped from said lubricant.

Claim 8

In a pumping mechanism having a housing, an internal oil reservoir therein filled with lubricant, a plurality of reciprocating pistons each in a stationary cylindrical bore, and means in said reservoir for reciprocating said piston, the combination comprising: a first body in said housing with one end forming a wall of said reservoir and having a bore for each cylindeR, a sleeve member fitting snugly in each said bore and providing said cylindrical bore, said sleeve having a first end in said reservoir and a second end distant therefrom having an annular chamber meeting said cylindrical bore at a shoulder, said sleeve having an exterior longitudinally extending groove extending from near said shoulder to said first end and having a bored passage connecting said groove to said annular chamber adjacent said shoulder, each said piston having a first end in said reservoir and a first portion having a diameter just enough smaller than said cylindrical bore to enable passage of oil therebetween during reciprocation, said piston having a second end beyond said second end of said sleeve member at all times and a second portion smaller in diameter than said first portion extending from said second end and meeting said first portion at a rim always lying within said cylindrical bore, a second body spaced from said first body having a bore in which said second piston portion reciprocates, an annular bearing member between said first and second bodies and closing said annular chamber, an O-ring in said annular chamber and movable between said shoulder and said bearing member and sealing between said second portion of said piston and said sleeve and having a position closing the passage between said chamber and said groove and a position opening that passage, sealing means sealing between said second body and said second portion of said piston, and, pumping mechanism in said second body and actuated by the alternate suction and pressure provided by said second portion of said piston in said second body, said sealing means sealing off the fluid being pumped from said lubricant, while said O-ring acts as a valve opening and closing the passage between said groove and said cylindrical bore as the piston reciprocates, thereby lubricating said cylindrical bore and said piston.

Claim 9

In a pumping mechanism having a housing, an internal oil reservoir therein filled with lubricant, a plurality of reciprocating pistons each in a stationary cylindrical bore, and means in said reservoir for reciprocating said piston, the combination comprising: a first body in said housing with one end forming a wall of said reservoir and having a bore for each cylindeR, a sleeve member fitting snugly in each said bore and providing said cylindrical bore, said sleeve having a first end in said reservoir and a second end distant therefrom having an annular chamber meeting said cylindrical bore at a shoulder, said sleeve having an exterior longitudinally extending groove extending from near said shoulder to said first end and having a bored passage connecting said groove to said annular chamber adjacent said shoulder, each said piston having a first end in said reservoir and a first portion having a diameter just enough smaller than said cylindrical bore to enable passage of oil therebetween during reciprocation, said piston having a second end beyond said second end of said sleeve member at all times and a second portion smaller in diameter than said first portion extending from said second end and meeting said first portion at a rim always lying within said cylindrical bore, a second body spaced from said first body having a bore in which said second piston portion reciprocates, an annular bearing member between said first and second bodies and closing said annular chamber, an O-ring in said annular chamber and movable between said shoulder and said bearing member and sealing between said second portion of said piston and said sleeve and having a position closing the passage between said chamber and said groove and a position opening that passage, sealing means sealing between said second body and said second portion of said piston, and, pumping mechanism in said second body and actuated by the alternate suction and pressure provided by said second portion of said piston in said second body, said sealing means sealing off the fluid being pumped from said lubricant, while said O-ring acts as a valve opening and closing the passage between said groove and said cylindrical bore as the piston reciprocates, thereby lubricating said cylindrical bore and said piston.

Claim 10

The combination of claim 6 wherein said second piston portion is about 0.010 inch smaller in diameter than said first piston portion.

Claim 11

The combination of claim 7 wherein said diameter of said first piston portion is about 0.0015 to 0.0025 inch less than that of said cylindrical bore.

Claim 12

The combination of claim 6 wherein said second body has an enlarged annular recess facing said annular bearing member and said sealing means comprises an elastomeric sealing ring in said annular recess and a back-up ring in said annular recess between said sealing ring and said bearing member.

Claim 13

The combination of claim 9 wherein said annular recess extends into a recessed portion of said bearing member.

Claim 14

The combination of claim 6 having an annular disk between said first and second body members slightly thinner than said bearing member and having a through opening for loosely receiving said bearing member.

Claim 15

The combination of claim 6 wherein said pumping mechanism comprises a drive shaft having a swash plate theron in said internal reservoir engaging said pistons for reciprocation thereof, an external oil-cooling reservoir, inlet means for said oil into said internal reservoir near the axial center thereof adjacent to said drive shaft and connected to said external reservoir by an inlet conduit, and outlet means for said oil from said reservoir adjacent the periphery thereof and connected to said external reservoir by an outlet conduit, the rotation of said drive shaft and its swash plate in said internal reservoir circulating oil from said inlet means to said outlet means and through said external reservoir to said inlet means.

Claim 16

The combination of claim 6 wherein said housing comprises a cylindrical reservoir-containing portion closed at one end and bolted at its other end to said first body for ready disassembly and reassembly.

Claim 17

The combination of claim 13 wherein said closed end of said reservoir portion is bolted thereon for easy removal.

Claim 18

The combinaTion of claim 13 wherein said first and second body members are bolted together for easy disassembly and reassembly.

Claim 19

In a pumping mechanism having a housing, an oil reservoir therein filled with lubricant, a plurality of reciprocating pistons each in a stationary cylindrical bore, means in said reservoir for reciprocating said piston, the combination comprising: a first body in said housing with one end forming a wall of said reservoir and having a first bore for each cylinder, each said first bore having a first end facing said reservoir and a second end distant therefrom, each said piston having a first end in said reservoir and a first portion having a diameter just enough smaller than said cylindrical bore to enable passage of oil therebetween during reciprocation, said piston having a second end beyond said second end of said first bore at all times and a second portion smaller in diameter than said first portion extending from said second end and meeting said first portion at a rim always lying within said cylindrical bore, a second body spaced from said first body having a second bore in which said second piston portion reciprocates and having an enlarged annular recess, an annular bearing member between said first and second bodies and closing said annular recess, a sealing ring of circular cross-section in said annular recess sealing between said second body and said second portion of said piston, and having a cross-sectional diameter slightly larger than the radial width of said recess, a back-up ring in said annular recess between said sealing ring and said bearing member, said back-up ring having substantially the same cross-sectional radial width as said recess, said recess being longer in its axial extent than the combined axial extent of said back-up ring and said crosssectional diameter of said sealing ring, said two rings being the only members in said recess, and pumping mechanism in said second body and actuated by the suction of said second portion of said piston in said second body, said sealing ring sealing off the fluid being pumped from said lubricant.

Claim 20

In a pumping mechanism having a housing, an oil reservoir therein filled with lubricant, a plurality of reciprocating pistons each in a stationary cylindrical bore, means in said reservoir for reciprocating said piston, the combination comprising: a first body in said housing with one end forming a wall of said reservoir and having a first bore for each cylinder, each said first bore having a first end facing said reservoir and a second end distant therefrom, each said piston having a first end in said reservoir and a first portion having a diameter just enough smaller than said cylindrical bore to enable passage of oil therebetween during reciprocation, said piston having a second end beyond said second end of said first bore at all times and a second portion smaller in diameter than said first portion extending from said second end and meeting said first portion at a rim always lying within said cylindrical bore, a second body spaced from said first body having a second bore in which said second piston portion reciprocates and having an enlarged annular recess, an annular bearing member between said first and second bodies and closing said annular recess, a sealing ring of circular cross-section in said annular recess sealing between said second body and said second portion of said piston, and having a cross-sectional diameter slightly larger than the radial width of said recess, a back-up ring in said annular recess between said sealing ring and said bearing member, said back-up ring having substantially the same cross-sectional radial width as said recess, said recess being longer in its axial extent than the combined axial extent of said back-up ring and said crosssectional diameter of said sealing ring, said two rings being the only members in said recess, and pumping mechanism in said second body and actuated by the suction of said second portion of said piston in said second body, said sealing ring sealing off the fluid being pumped from said lubricant.

Claim 21

The combination of claim 16 wherein said sealing ring is elastomeric and said back-up ring is non-elastomeric.

Claim 22

The combination of claim 17 wherein said back-up ring is a combination of glass fibers, bronze, and tetrafluoroethylene.

Claim 23

The combination of claim 16 having an annular disk thinner than said bearing means between said first and second body members and having openings therein for holding each said bearing means loosely.

Claim 24

The combination of claim 16 having a plurality of sleeve members each fitting snugly in one said first bore and providing a said cylindrical bore, said sleeve having a first end in said reservoir and a second end distant therefrom having an annular chamber meeting said cylindrical bore at a shoulder, said sleeve having an exterior longitudinally extending groove extending from near said shoulder to said first end and having a bored passage connecting said groove to said annular chamber adjacent said shoulder, and means for closing said bored passage when said piston moves in one direction and opening it when said piston moves in the opposite direction.

Claim 25

In a pumping mechanism having a housing, an oil reservoir therein filled with lubricant, a plurality of reciprocating pistons each in a stationary cylindrical bore, means in said reservoir for reciprocating said piston, the combination comprising: a first body in said housing with one end forming a wall of said reservoir and having a first bore for each cylinder, each said first bore having a first end facing said reservoir and a second end distant therefrom, each said piston having a first end in said reservoir and a first portion having a diameter just enough smaller than said cylindrical bore to enable passage of oil therebetween during reciprocation, said piston having a second end beyond said second end of said first bore at all times and a secOnd portion smaller in diameter than said first portion extending from said second end and meeting said first portion at a rim always lying within said cylindrical bore, a second body spaced from said first body having a second bore in which said second piston portion reciprocates and having an enlarged annular recess, an annular bearing member between said first and second bodies and closing said annular recess, a sealing ring in said annular recess sealing between said second body and said second portion of said piston, a back-up ring in said annular recess between said sealing ring and said bearing member, pumping mechanism in said second body and actuated by the suction of said second portion of said piston in said second body, said sealing ring sealing off the fluid being pumped from said lubricant, a plurality of sleeve members each fitting snugly in one said first bore providing a said cylindrical bore, said sleeve having a first end in said reservoir and a second end distant therefrom having an annular chamber meeting said cylindrical bore at a shoulder, said sleeve having an exterior longitudinally extending groove extending from near said shoulder to said first end and having a bored passage connecting said groove to said annular chamber adjacent said shoulder, means for closing said bored passage when said piston moves in one direction and opening it when said piston moves in the opposite direction, an O-ring in said annular chamber movable between said shoulder and said spacing member and sealing between said second portion of said piston and said sleeve and having a position closing the passage between said chamber and said groove and a position opening that passage, said O-ring acting as a valve opening and closing the passage between said groove and said cylindrical bore as the piston reciprocates, thereby lubricating said cylindrical bore and said piston.

Claim 26

In a pumping mechanism having a housing, an oil reservoir therein filled with lubricant, a plurality of reciprocating pistons each in a stationary cylindrical bore, means in said reservoir for reciprocating said piston, the combination comprising: a first body in said housing with one end forming a wall of said reservoir and having a first bore for each cylinder, each said first bore having a first end facing said reservoir and a second end distant therefrom, each said piston having a first end in said reservoir and a first portion having a diameter just enough smaller than said cylindrical bore to enable passage of oil therebetween during reciprocation, said piston having a second end beyond said second end of said first bore at all times and a secOnd portion smaller in diameter than said first portion extending from said second end and meeting said first portion at a rim always lying within said cylindrical bore, a second body spaced from said first body having a second bore in which said second piston portion reciprocates and having an enlarged annular recess, an annular bearing member between said first and second bodies and closing said annular recess, a sealing ring in said annular recess sealing between said second body and said second portion of said piston, a back-up ring in said annular recess between said sealing ring and said bearing member, pumping mechanism in said second body and actuated by the suction of said second portion of said piston in said second body, said sealing ring sealing off the fluid being pumped from said lubricant, a plurality of sleeve members each fitting snugly in one said first bore providing a said cylindrical bore, said sleeve having a first end in said reservoir and a second end distant therefrom having an annular chamber meeting said cylindrical bore at a shoulder, said sleeve having an exterior longitudinally extending groove extending from near said shoulder to said first end and having a bored passage connecting said groove to said annular chamber adjacent said shoulder, means for closing said bored passage when said piston moves in one direction and opening it when said piston moves in the opposite direction, an O-ring in said annular chamber movable between said shoulder and said spacing member and sealing between said second portion of said piston and said sleeve and having a position closing the passage between said chamber and said groove and a position opening that passage, said O-ring acting as a valve opening and closing the passage between said groove and said cylindrical bore as the piston reciprocates, thereby lubricating said cylindrical bore and said piston.