# US 5,975,864 A · Pump with self-reciprocating pistons > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,975,864 A - Document ID: US5975864A - Status: Granted - Kind: A - Application number: 09/026,502 - Filed: 1998-02-19 - Granted: 1999-11-02 - Earliest claimed: 1998-02-19 - Assignees: Jetech, Inc. - Inventors: Gerard J. De Santis; Stanley E. Reed - Web page: https://patentgrep.com/patent/US5975864A ## CPC - F04B 1/0452: Distribution members, e.g. valves (machines or pumps with cam-actuated distribution members at the outer ends of the cylinders F04B1/0472; machines or pumps with cam-actuated distribution members at the inner ends of the cylinders F04B1/0531; the piston-driving cams being provided with inlets and outlets F04B1/0535) - F04B 1/0413: Cams - F04B 1/0439: Supporting or guiding means for the pistons - F04B 1/0448: Sealing means, e.g. for shafts or housings (for pistons F04B1/0408 {; Stoffing boxes F04B53/164}) - F04B 1/047: with actuating or actuated elements at the outer ends of the cylinders - F04B: POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS (machines for liquids, or pumps, of rotary-piston or oscillating-piston type F04C; non-positive-displacement pumps F04D; pumping of fluid by direct contact of another fluid or by using inertia of fluid to be pumped F04F) ## Abstract A pump for providing a pressurized fluid flow. The pump includes a pump casing that defines a pump chamber. A pump shaft is has a head end in the pump chamber; the head end has a circumferential outer surface. The pump shaft head end has inwardly extending piston chambers. A discharge manifold is formed in the pump shaft head end. The discharge manifold has one end in fluid communication with the piston chambers and a second end in fluid communication with a discharge conduit that extends outside of the pump casing. A piston is mounted in each piston chamber. The pistons are formed with flow-through bores that provide fluid communication between the pump chamber and the piston chambers. A suction valve associated with each piston regulates fluid flow from the pump chamber through the flow-through bore into the associated piston chamber. Discharge valves regulate fluid flow from each piston chamber into the discharge manifold. The head end of the pump shaft is axially offset from the center axis of the pump chamber. As the pump shaft is rotated, the pistons engage in reciprocal motion in their piston chambers. Fluid is introduced into the pump chamber. When each piston is in its extended position, the suction valve allows fluid flow into the piston chamber. When each piston is retracted, it forces the fluid in the associated piston chamber through the discharge valve, through the discharge manifold and out the discharge conduit. ## Claims ### Claim 1 A pump, said pump including: a pump casing, said pump casing being formed with a curved inner wall that defines a pump chamber and an inlet bore extending into an outer perimeter portion of said pump chamber; a pump head rotatably mounted in said pump chamber, said pump head having a center and a circumferentially extending outer wall that is inwardly spaced from said outer perimeter of said pump chamber, said pump head defining at least one piston chamber that extends from said outer wall to the center of said pump head and a discharge manifold that extends longitudinally through the center of said pump head, wherein said pump head is mounted in said pump chamber to rotate eccentrically relative to said inner wall of said pump casing so that as said pump head rotates, the distance between a point on said outer wall of said pump head and said inner wall of the pump casing varies; a discharge conduit mounted to said pump casing, said discharge conduit having a first end that is disposed in said pump chamber and is in fluid communication with said discharge manifold and a second end in fluid communication with said first end that is located outside of said pump casing; a piston disposed in said piston chamber, said piston having a flow-through bore that provides a fluid communication path between said pump chamber and said piston chamber; a biasing member disposed in said piston chamber for urging said piston toward said inner wall of said pump casing; a suction valve in said flow-through bore of said piston for allowing fluid flow from said pump chamber into said piston chamber when fluid pressure in said pump chamber exceeds fluid pressure in said piston chamber by a select amount; and a discharge valve disposed between said piston chamber and said discharge manifold for allowing fluid flow from said piston chamber into said discharge manifold when fluid pressure in said piston chamber exceeds fluid pressure in said discharge manifold by a select amount. ### Claim 2 (depends on 1) The pump of claim 1, wherein said inner wall of said pump casing has a circular profile so that said pump chamber has a circular profile, said outer wall of said pump head has a circular profile and said pump head is mounted in said pump chamber so that said pump head is axially offset relative to a center axis of said pump chamber. ### Claim 3 (depends on 1) The pump of claim 1, further including a shaft extending from said pump head, said shaft extending out of said pump casing. ### Claim 4 (depends on 1) The pump of claim 1, wherein: said pump head is provided with a plurality of said pistons, each said piston being disposed in a separate piston chamber defined in said pump head; and separate said discharge valves are located between each said piston chamber and said discharge manifold for controlling fluid flow from said piston chambers to said discharge manifold. ### Claim 5 (depends on 1) The pump of claim 1, wherein a plunger stroker is fitted over a head end of said at least one piston so that said plunger stroker extends beyond said outer wall of said pump head and said biasing member urges said plunger stroker towards said inner wall of said pump casing, said plunger stroker being formed with a flow-through bore for establishing fluid communication between said pump chamber and said flow-through bore of said piston and said plunger stroker being capable of lateral movement independent of lateral movement of said piston. ### Claim 6 (depends on 5) The pump of claim 5, wherein a bearing assembly is located between said plunger stroker and said inner wall of said pump casing, said bearing assembly including at least one ring capable of rotating relative to said pump casing. ### Claim 7 (depends on 5) The pump of claim 5, further including a shoe located between said plunger stroker and said inner wall of said pump casing, said shoe being pivotally attached to said pump head to both rotate with said pump head and to move with longitudinal movement of said plunger stroker. ### Claim 8 (depends on 1) The pump of claim 1, wherein a bearing assembly is located between said piston and said inner wall of said pump casing, said bearing assembly including at least one ring capable of rotating relative to said pump casing. ### Claim 9 (depends on 1) The pump of claim 1, further including a shoe located between said piston and said inner wall of said pump casing, said shoe being pivotally attached to said pump head to both rotate with said pump head and to move with longitudinal movement of said piston. ### Claim 10 A pump assembly including: a pump casing, said pump casing being formed with: an inner wall having a circular profile so as to define a circular pump chamber, said pump chamber having a center axis; and an inlet bore that extends into an outer perimeter portion of said pump chamber; a pump head rotatably disposed in said pump chamber, said pump head having a center axis and being formed with: a circumferentially extending, circular outer wall; a plurality of piston chambers located around said outer wall that extend towards said pump head center axis; a discharge manifold that extends longitudinally along said pump center axis; and a plurality of secondary bores, each said secondary bore extending between a separate one of said piston chambers and said discharge manifold wherein, said pump head is axially offset from said pump chamber center axis, so that, as said pump head rotates, the distance between a point on said outer wall of said pump head and said inner wall of said pump casing varies; a discharge conduit mounted to said pump casing, said discharge conduit having a first end located in said pump chamber that is in fluid communication with said discharge manifold and a second end located outside of said pump casing that is in fluid communication with said first end; a plurality of piston assemblies, each said piston assembly being seated in a separate one of said piston chambers and including: a piston seated in said piston chamber; a plunger stroker seated in said piston chamber above said piston and dimensioned to extend beyond said outer wall of said pump head, said plunger stroker being fitted over said piston to move laterally relative to said piston; and a biasing spring located in said piston chamber for urging said piston and said plunger stroker outwardly toward said inner wall of said pump casing wherein, said piston and said plunger stroker are each formed with a flow-through bore, said flow-through bores being positioned to allow fluid flow from said pump chamber into said piston chamber; a plurality of suction valves, each said suction valve being positioned in a separate said piston flow-through bore for allowing fluid flow through said flow-through bore when fluid pressure in said pump chamber exceeds fluid pressure in said piston chamber by a set amount; and a plurality of discharge valves, each said discharge valve being located in a separate one of said secondary bores for allowing fluid flow through said secondary bore and into said discharge manifold when fluid pressure in said secondary bore exceeds fluid pressure in said discharge manifold. ### Claim 11 (depends on 10) The pump assembly of claim 10, further including a plurality of shoes, each said shoe being located between a separate said plunger stroker and said inner wall of said pump casing and being pivotally connected to said pump head to rotate with said pump head and to move with longitudinal displacement of said plunger stroker with which said shoe is associated. ### Claim 12 (depends on 11) The pump assembly of claim 11, further including a race disposed between said shoes and said inner wall of said pump casing. ### Claim 13 (depends on 10) The pump assembly of claim 10, further including a plurality of stuffing boxes mounted to said outer wall of said pump head, each said stuffing box defining a separate one of said piston chambers. ### Claim 14 (depends on 13) The pump assembly of claim 13, further including a plurality of shoes, each said shoe being located between a separate said plunger stroker and said inner wall of said pump casing and being pivotally connected to said pump head to rotate with said pump head and to move with longitudinal displacement of said plunger stroker with which said shoe is associated. ### Claim 15 (depends on 10) The pump assembly of claim 10, further including a bearing assembly located between said plunger strokers and said inner wall of said pump casing. ### Claim 16 (depends on 15) The pump assembly of claim 15, wherein said bearing assembly includes an outer race located adjacent said inner wall of said pump casing and an inner race located between said outer race and said plunger strokers, said inner race being configured to rotate relative to said outer race. ### Claim 17 A method of providing a pressurized fluid flow including the steps of: providing a pump casing having an inner wall that defines a cylindrical pump chamber, an inlet bore into said pump chamber and a discharge conduit having a first end located in said pump chamber and a second end located outside of said pump casing; providing a pump head with a plurality of pistons in said pump chamber, said pump head having a center axis, a circular outer wall, a plurality of piston chambers that extend from said outer wall towards said center axis and a discharge manifold, said discharge manifold having one end in fluid communication with said piston chambers and a second end in fluid communication with said first end of said discharge conduit wherein each said piston is seated on one of said piston chambers and is formed with a flow through bore that allows fluid communication between said pump chamber and said piston chamber in which said piston is seated; rotating said pump head and said pistons so that, during said rotation, said pistons are moved reciprocally in and out of said piston chambers; introducing fluid into said pump chamber under pressure so that said fluid flows into said piston flow-through bores; when fluid pressure in each said piston flow-through bore exceeds fluid pressure in said piston chamber with which said flow-through bore is associated by a select amount, allowing fluid flow from said flow-through bore into said piston chamber; and when fluid pressure in each said piston chamber exceeds fluid pressure in said discharge manifold, allowing fluid flow from said piston chamber to said discharge manifold so that said fluid will flowthrough said discharge manifold and out of said discharge conduit. ### Claim 18 (depends on 17) The method of providing pressurized fluid flow of claim 17, wherein said pump head has opposed front and rear surfaces that are spaced inwardly from adjacent surfaces of said pump chamber so that when fluid is introduced into said pump chamber, said fluid flows around said front and rear surfaces of said pump head. ### Claim 19 (depends on 17) The method of providing pressurized fluid flow of claim 17, wherein said pistons are moved reciprocally in and out of said piston chambers by: positioning said pump head in said pump chamber so that said pump head is axially offset relative to said pump chamber so that as said pump head rotates the distance between a fixed point on said pump head and said inner wall of said pump casing varies; and biasing said pistons outwardly towards said inner wall of said pump casing so that as said pump head is rotated, said pistons are moved reciprocally in and out of said piston chambers. ### Claim 20 (depends on 17) The method of providing pressurized fluid flow of claim 17, wherein a plunger stroker is provided over each said piston, each said plunger stroker being able to move laterally relative to said piston with which said plunger stroker is associated, so that when said pistons are subjected to said outward biasing, said plunger strokers are located between said pistons and said inner wall of said pump chamber. ### Claim 21 (depends on 20) The method of providing pressurized fluid of claim 20, further including the step of providing a separate shoe between each said plunger stroker and said inner wall of said pump chamber, each said shoe being pivotally attached to said pump head so that as said pump head, said pistons and said plunger strokers engage in said rotation, said shoe rotates with said plunger stroker with which said shoe rotates and engages in longitudinal movement with said plunger stroker.