US4276003A — Reciprocating piston pump system with screw drive

Claim 1

Independent Claim 140 words

A pump comprising: a cylinder having inlet and outlet means for receiving and allowing the exit of fluid; a piston having an end portion in said cylinder and a threaded portion; a motor having a stator and a rotor; nut means coupled to said rotor to rotate with it, and threadably engaged with said piston threaded portion, said nut means including walls defining an internal thread, a channel extending in a helix along said walls, and pressured fluid feed means coupled to said channel to provide hydraulic fluid to said channel; said channel having a plurality of interruptions therealong forming barriers to the free flow of fluid between channel portions that lie on opposite sides of the barrier, and said feed means including a plurality of restricted feed conduits leading to different of said channel portions to supply fluid thereto.

Claim 2

Dependent Claim 140 words

A pump comprising: a cylinder having inlet and outlet means for receiving and allowing the exit of fluid; a piston having an end portion in said cylinder and a threaded portion; a motor having a stator and a rotor; nut means coupled to said rotor to rotate with it, and threadably engaged with said piston threaded portion, said nut means including walls defining an internal thread, a channel extending in a helix along said walls, and pressured fluid feed means coupled to said channel to provide hydraulic fluid to said channel; said channel having a plurality of interruptions therealong forming barriers to the free flow of fluid between channel portions that lie on opposite sides of the barrier, and said feed means including a plurality of restricted feed conduits leading to different of said channel portions to supply fluid thereto.

Claim 3

Dependent Claim 26 words

The pump described in claim 1 wherein: said barriers are positioned so there are at least three barriers in every approximately 360° along said internal thread.

Claim 4

Dependent Claim 98 words

In a pump with an inlet and outlet and that includes a reciprocating piston with a screw portion that is advanced by a motor having a rotor, the improvement of a hydrostatic nut apparatus for transmitting power from the rotor to the piston, comprising; a hydrostatic nut which includes walls defining a hylical groove, including side walls and a radially outer wall, for threadably receiving said piston screw portion, said side walls having a plurality of fluid-holding recesses therein spaced along the helical groove; and pressured fluid supply means coupled to said recesses to supply pressured fluid thereto.

Claim 5

Dependent Claim 98 words

In a pump with an inlet and outlet and that includes a reciprocating piston with a screw portion that is advanced by a motor having a rotor, the improvement of a hydrostatic nut apparatus for transmitting power from the rotor to the piston, comprising; a hydrostatic nut which includes walls defining a hylical groove, including side walls and a radially outer wall, for threadably receiving said piston screw portion, said side walls having a plurality of fluid-holding recesses therein spaced along the helical groove; and pressured fluid supply means coupled to said recesses to supply pressured fluid thereto.

Claim 6

Dependent Claim 47 words

The pump described in claim 3 including: a nut housing rotatably supporting said hydrostatic nut; and a coupling extending between said rotor and said nut, said coupling constructed to transmit torque but to permit at least slight shifting in position of said nut relative to said rotor.

Claim 7

Dependent Claim 126 words

Pumping apparatus comprising: a piston having a threaded portion and having an end; a nut threadably engaged with said piston; a motor having a stator, and having a rotor coupled to said nut to rotate it and to move the piston axially as the rotor turns; a cylinder receiving said end of said piston, and having inlet and outlet valves; and means for energizing said motor to rotate said rotor; said nut includes walls defining an internal thread with side walls, said side walls having a plurality of recesses spaced along the helix defined by the internal thread for holding hydraulic fluid, and means for applying hydraulic fluid to said recesses including a plurality of restricted feed conduits leading to said recesses to supply fluid thereto.

Claim 8

Dependent Claim 126 words

Pumping apparatus comprising: a piston having a threaded portion and having an end; a nut threadably engaged with said piston; a motor having a stator, and having a rotor coupled to said nut to rotate it and to move the piston axially as the rotor turns; a cylinder receiving said end of said piston, and having inlet and outlet valves; and means for energizing said motor to rotate said rotor; said nut includes walls defining an internal thread with side walls, said side walls having a plurality of recesses spaced along the helix defined by the internal thread for holding hydraulic fluid, and means for applying hydraulic fluid to said recesses including a plurality of restricted feed conduits leading to said recesses to supply fluid thereto.

Claim 9

Dependent Claim 180 words

A pump comprising: a piston with a threaded portion; a cylinder having an inlet and an outlet, and having an open end for slideably receiving said piston, said piston being small enough in diameter to leave a clearance between it and said cylinder; means for reciprocating said piston including a rotor, a nut engaged with the threaded piston portion, and means coupling said rotor and nut; and sealing means located at said cylinder open end to seal in fluid, including a contact seal surrounding and in contact with said piston to seal thereagainst, and a fluid-emitting member closely surrounding said piston but with a gap between them and means for applying pressured fluid to said gap, whereby to minimize wear on the contact seal; said nut including walls defining an internal thread with side walls, said side walls having a plurality of recesses spaced along the helix defined by the internal thread for holding hydraulic fluid, and means for applying hydraulic fluid to said recesses including a plurality of restricted feed conduits leading to said recesses to supply fluid thereto.

Claim 10

Dependent Claim 180 words

A pump comprising: a piston with a threaded portion; a cylinder having an inlet and an outlet, and having an open end for slideably receiving said piston, said piston being small enough in diameter to leave a clearance between it and said cylinder; means for reciprocating said piston including a rotor, a nut engaged with the threaded piston portion, and means coupling said rotor and nut; and sealing means located at said cylinder open end to seal in fluid, including a contact seal surrounding and in contact with said piston to seal thereagainst, and a fluid-emitting member closely surrounding said piston but with a gap between them and means for applying pressured fluid to said gap, whereby to minimize wear on the contact seal; said nut including walls defining an internal thread with side walls, said side walls having a plurality of recesses spaced along the helix defined by the internal thread for holding hydraulic fluid, and means for applying hydraulic fluid to said recesses including a plurality of restricted feed conduits leading to said recesses to supply fluid thereto.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1984-06-29	1984-12-29	1985-06-30	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1988-06-29	1988-12-29	1989-06-30	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1992-06-29	1992-12-29	1993-06-30	$7700.00	Window Closed / Lapsed

Reciprocating piston pump system with screw drive

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