Claims
- 1. A pump for delivery of a fluid, comprising:
- first and second reciprocating pistons, wherein the first piston communicates with a first pumping chamber, and the second piston communicates with a second pumping chamber;
- a rotary cam that reciprocates the pistons as the cam rotates;
- an inlet flow path that communicates with the first pumping chamber when the first piston is reciprocating in a direction that draws fluid into the first pumping chamber, and with the second pumping chamber when the second piston is reciprocating in a direction that draws fluid into the second pumping chamber;
- an outlet flow path that communicates with the first pumping chamber when the first piston is reciprocating in a direction that expels fluid out of the first pumping chamber, and with the second pumping chamber when the second piston is reciprocating in a direction that expels fluid out of the second pumping chamber;
- a control surface carried by the cam, wherein the control surface alternately moves between a first position and a second position, and flow channels are inscribed in the control surface, wherein when the control surface is in the first position the inlet flow path to the first pumping chamber is continuous through the flow channels and the outlet flow path from the first pumping chamber is interrupted, and the inlet flow path to the second pumping chamber is interrupted and the outlet flow path from the second pumping chamber is continuous through the flow channels, and when the control surface is in the second position the inlet flow path to the second pumping chamber is continuous through the flow channels and the outlet flow path from the second pumping chamber is interrupted, and the inlet flow path to the first pumping chamber is interrupted and the outlet flow path from the first pumping chamber is continuous through the flow channels.
- 2. The pump of claim 1 wherein the cam moves the first and second pistons such that the first piston expels fluid when the second piston is drawing fluid in, and the first piston draws in fluid while the second piston expels fluid, and the cam further moves the control valve between the first and second positions, with the control valve in the first position when the first piston draws in fluid and the second piston expels fluid, and the control valve in the second position when the first piston expels fluid and the second piston draws in fluid.
- 3. The pump of claim 1 wherein the cam rotates around an axis that is substantially parallel to the first and second pistons.
- 4. The pump of claim 1 wherein the cam control surface has a variable shape that reciprocates the pistons.
- 5. The pump of claim 1 wherein the control surface impinges against and reciprocates the pistons, which are spring biased against the cam surface, and the control surface also moves the control valve between the first position and the second position of the control valve.
- 6. The pump of claim 4 wherein the variable shape of the surface is provided by a raceway in the surface of the cam.
- 7. The pump of claim 4 wherein the variable shape of the control surface is a slanted surface.
- 8. The pump of claim 6 wherein the raceway has a surface that reciprocates the first piston faster in the direction that draws fluid into the first pumping chamber than in the direction that expels fluid out of the first pumping chamber, and the surface of the raceway reciprocates the second piston faster in the direction that draws fluid into the second pumping chamber than in the direction that expels fluid out of the second pumping chamber.
- 9. The pump of claim 1 wherein the control surface is a variable shaped surface that reciprocates the first and second pistons as the cam rotates, and the control surface is rotated by the cam, wherein the control surface has a plurality of grooves inscribed therein that establish passageways through which the control valve directs the flow of the fluid to establish the continuous and interrupted flow paths when the control valve is in the first and second positions.
- 10. The pump of claim 9 wherein the plurality of grooves comprise:
- a first annular groove in communication with one of the inlet or outlet flow path throughout rotation of the cam;
- a second groove that is coincident with an inner circle circumscribed by the first groove;
- an indentation on the axis of rotation of the cam that, throughout rotation of the cam, is in communication with the inlet or outlet flow path that is not in communication with the first annular groove;
- wherein the second groove comprises a first groove portion and a second groove portion that are discontinuous with each other, and the first and second groove portions alternately communicate with the first and second pumping chambers as the control surface rotates;
- a first connecting groove that connects the first groove portion of the second groove with the indentation on the axis of rotation; and
- a second connecting groove that connects the second groove portion of the second groove with the first annular groove.
- 11. The pump of claim 10 wherein the control surface apposes a control plate that cooperatively with the grooves forms the passageways, and the control plate includes a plurality of openings therethrough that establish communication between the passageways and the inlet and outlet flow pathways, and between the passageways and the first and second pumping chambers.
- 12. A pump for continuous delivery of a fluid, comprising:
- an inlet flow path through which fluid is delivered to the pump;
- an outlet flow path through which fluid is delivered from the pump;
- a plurality of reciprocating pistons, wherein each piston communicates with a pumping chamber to draw fluid from the inlet flow path into the pumping chamber as the piston moves in a first direction, and to force fluid out of the pumping chamber through the outlet flow path as the piston moves in a second direction;
- a rotary cam that rotates around an axis of rotation and reciprocates the pistons as the cam rotates;
- a control surface carried by the cam and intersected by the axis of rotation, wherein flow control channels are inscribed in the control surface, and the flow control channels comprise:
- a continuous annular outer channel;
- a discontinuous annular inner channel circumscribed by the outer continuous annular channel and forming a first arc shaped inner channel portion and a second arc shaped inner channel portion;
- a localized indentation at the center of rotation of the cam;
- a first communicating channel between the localized indentation and the first arc shaped inner channel portion;
- a second communicating channel between the outer channel and the second arc shaped inner channel portion;
- separate pumping chamber flow paths communicating between the continuous outer annular channel and each of the pumping chambers;
- a stationary control plate that fits against the control surface to form closed passageways between the control plate and the channels in the control surface, wherein the control plate has
- a first opening through the control plate positioned to communicate with the continuous annular outer channel and one of the inlet flow path or outlet flow path throughout rotation of the control surface;
- a second opening through the control plate positioned to communicate, throughout rotation of the control surface, with the localized indentation and the one of the inlet flow path or outlet flow path that does not communicate with the annular outer channel; and
- a plurality of pumping chamber openings positioned to communicate between the pumping chamber flow paths and the inner channel on the control surface.
- 13. The pump of claim 12 wherein the rotary cam has a raceway with a patterned surface over which the pistons ride to reciprocate as the cam rotates.
- 14. The pump of claim 12 wherein the rotary cam has a slanted surface that impinges against a bearing end of the pistons to reciprocate the pistons as the cam rotates.
- 15. The pump of claim 12 wherein the plurality of reciprocating pistons comprises an odd number of reciprocating pistons.
- 16. The pump of claim 15 wherein the odd number of reciprocating pistons is three reciprocating pistons.
- 17. A pump for substantially pulseless delivery of a fluid, comprising:
- a housing containing first and second spring biased piston assemblies, the first piston assembly comprising a first piston bore with a first reciprocating piston disposed in the first piston bore, and a first pumping chamber in the first piston bore, the second piston assembly comprising a second piston bore with a second reciprocating piston disposed in the second piston bore, and a second pumping chamber in the second piston bore;
- a rotary cam that reciprocates the pistons as the cam rotates;
- an inlet flow path through the housing and that communicates with the first pumping chamber when the first piston is reciprocating in a direction that draws fluid into the first pumping chamber, and with the second pumping chamber when the second piston is reciprocating in a direction that draws fluid into the second pumping chamber;
- an outlet flow path through the housing that communicates with the first pumping chamber when the first piston is reciprocating in a direction that expels fluid out of the first pumping chamber, and with the second pumping chamber when the second piston is reciprocating in a direction that expels fluid out of the second pumping chamber;
- a control surface carried by the cam, wherein the control surface alternately moves between a first position and a second position, and flow channels are inscribed in the control surface wherein when the control surface is in the first position the inlet flow path to the first pumping chamber is continuous through the flow channels and the outlet flow path from the first pumping chamber is interrupted, and the inlet flow path to the second pumping chamber is interrupted and the outlet flow path from the second pumping chamber is continuous through the flow channels, and when the control surface is in the second position the inlet flow path to the second pumping chamber is continuous through the flow channels, and the outlet flow path from the second pumping chamber is interrupted, and the inlet flow path to the first pumping chamber is interrupted and the outlet flow path from the first pumping chamber is continuous through the flow channels; and
- wherein a bore axis for each piston bore is substantially parallel, and each reciprocating piston is reciprocated by the cam as the cam rotates around an axis parallel to the bore axis for each piston, and the cam moves the first and second pistons such that the first piston expels fluid when the second piston is drawing fluid in, and the first piston draws in fluid while the second piston expels fluid, and the cam further moves the control surface between the first and second positions, with the control surface in the first position when the first piston draws in fluid and the second piston expels fluid, and the control surface in the second position when the first piston expels fluid and the second piston draws in fluid.
- 18. The pump of claim 17 wherein the cam has an impingement surface shaped to impinge the pistons, and the impingement surface is shaped to reciprocate the pistons such that the fluid delivery of the pump is substantially constant.
- 19. The pump of claim 18 wherein the impingement surface is shaped to displace each piston in a positive displacement direction away from a neutral position to expel fluid from the pumping chamber, followed by a reversal of piston direction to a negative displacement direction that draws fluid into the pumping chamber, and the period of time during which negative displacement of each piston occurs is less than the period of time during which positive displacement of each piston occurs, and the positive displacements of the first and second pistons are in staggered phases, such that the output flow of the first and second pistons superimpose to provide a substantially continuous fluid flow from the pump.
- 20. The pump of claim 19 wherein the cam moves at a constant rotational speed and is shaped to displace the first piston in the positive displacement direction in which fluid is forced out of the first pumping chamber, then hold the positive displacement of the first piston at a constant maximum displacement position, then displace the first piston in the negative displacement direction until a maximum negative displacement position is reached;
- the cam is further shaped to displace the second piston in the positive displacement direction in which fluid is forced out of the second pumping chamber, then hold the positive displacement at a constant maximum positive displacement position, then displace the second piston in the negative displacement direction until the maximum negative displacement is reached;
- displacement of the first piston in the positive displacement direction begins when the second piston first reaches its maximum positive displacement, and displacement of the first piston in the positive displacement direction continues during the entire period during which the second piston is displaced in the negative displacement direction and reaches the maximum negative displacement position of the second piston, the maximum positive displacement position of the first piston is reached as the maximum negative displacement of the second piston ends and displacement of the second piston in the positive direction begins;
- displacement of the first piston in the negative displacement direction begins during displacement of the second piston in the positive displacement direction, and the first piston reaches it maximum negative displacement position during the displacement of the second piston in the positive displacement direction.
- 21. The pump of claim 19 wherein the control surface comprises a valve member having a control surface with the flow channels inscribed therein, and a cover over the flow channels such that the flow channels and cover form closed fluid passageways therebetween, and in the first position of the control valve, the fluid passageways of the control valve establish fluid communication between the inlet and the first pumping chamber and the outlet and the second pumping chamber, and in the second position the valve member establishes fluid communication between the inlet and the second pumping chamber, and the outlet and the first pumping chamber.
- 22. The pump of claim 21 wherein the control surface rotates relative to the cover, and the cover has openings therethrough that communicate with the fluid passageways.
- 23. The pump of claim 19 wherein the control surface is part of a control valve comprising a control disc and the control surface is flat, and a cover with a flat inside face bears against the control surface, wherein the disc rotates relative to the cover about an axis of rotation, and flow channels in the control surface form, in cooperation with the overlying cover, an inlet passageway and an outlet passageway that do not communicate with each other;
- first, second, third and fourth bores extending through the cover, wherein the first bore is an inlet bore that communicates with the inlet line, the second bore is an outlet bore that communicates with the outlet line, the third bore communicates with a flow path to the first pumping chamber, and the fourth bore communicates with a flow path to the second pumping chamber;
- wherein the inlet passageway comprises an annular inlet passageway circumscribing an arcuate inlet passageway, and the annular and arcuate inlet passageways both have the same center and radius of curvature, and a communicating passageway extends radially on the control surface between the annular and arcuate passageways, and the outlet passageway comprises an arcuate outlet passageway with a center of curvature at the axis, and a communicating arm that extends from the arcuate outlet passageway to the center of curvature of the arcuate outlet passageway, and the distance from the axis of the arcuate inlet and outlet passageways is the same; and
- wherein the second bore extends through the cover at the axis to communicate with the arm of the outlet passageway, the distance between the axis and first bore is the same as the distance from the axis to the annular inlet passageway, and the distance between the axis and the third and fourth bores is the same as the radius from the axis to the arcuate inlet and outlet passageways.
- 24. The pump of claim 19 wherein the control valve comprises a spool valve disposed for axial movement in a spool valve bore in the housing with the spool valve bore axis substantially parallel to the bore axes of the pistons, and the spool valve has first and second necked down portions, with fluid communication between the inlet and the first pumping chamber being established through the first necked down portion when the spool valve is in the first position, fluid communication between the outlet and the second pumping chamber being established through the second necked down portion when the spool valve is in the first position, fluid communication between the inlet and the second pumping chamber being established through the second necked down portion when the spool valve is in the second position, and fluid communication between the outlet and the first pumping chamber being established through the first necked down portion when the spool valve is in the second position.
- 25. A pump for substantially pulseless delivery of a fluid, comprising:
- a housing containing first and second piston pump assemblies, the first piston pump assembly comprising a first spring biased reciprocating piston in a first piston bore, and a first pumping chamber formed in the first piston bore, the second piston pump assembly comprising a second spring biased reciprocating piston in a second piston bore, and a second pumping chamber formed in the second piston bore, the first and second piston bores having axes that are substantially parallel;
- a control valve in the housing that moves between a first and a second position, wherein the control valve has a first passageway connecting portion and a second passageway connecting portion;
- an inlet line into the housing that communicates with the control valve;
- an outlet line from the control valve out of the housing;
- a first pumping chamber passageway from the first pumping chamber to the control valve;
- a second pumping chamber passageway from the second pumping chamber to the control valve;
- a cam that moves at a constant rotational speed and impinges against the first and second pistons to move the first piston against its spring bias to force fluid out of the first pumping chamber, and subsequently allows the first piston to move with its spring bias to draw fluid into the first pumping chamber, and the cam further moves the second piston against its spring bias to force fluid out of the second pumping chamber, and subsequently allows the second piston to move with its spring bias to draw fluid into the second pumping chamber;
- where the cam has an axis of rotation that is substantially parallel to the axes of the first and second piston bores, and movement of the cam further moves the control valve between
- (a) a first position in which fluid communication is established between the inlet line and the first pumping chamber passageway through the first passageway connecting portion, as well as between the second pumping chamber passageway and the outlet line through the second passageway connecting portion, while blocking fluid communication between the outlet line and the first pumping chamber passageway, and the inlet line and the second pumping chamber passageway; and
- (b) a second position of the control valve in which fluid communication is established between the inlet line and the second pumping chamber passageway through the second passageway connecting portion, as well as between the outlet line and the first pumping chamber passageway, while blocking fluid communication between the outlet line and the second pumping chamber passageway, and the inlet line and the first pumping chamber passageway;
- wherein the cam is shaped to displace the first piston in a positive displacement direction in which fluid is forced out of the first pumping chamber, then hold the positive displacement of the first piston at a constant maximum displacement position, then displace the first piston in a negative displacement direction until a maximum negative displacement position is reached, and during the negative displacement of the first piston fluid is drawn into the first pumping chamber;
- the cam is further shaped to displace the second piston in a positive displacement direction in which fluid is forced out of the second pumping chamber, then hold the positive displacement at a constant maximum positive displacement position, then displace the second piston in a negative displacement direction until the maximum negative displacement is reached, and during the negative displacement of the second piston fluid is drawn into the second pumping chamber;
- displacement of the first piston in the positive displacement direction begins when the second piston first reaches its maximum positive displacement, and displacement of the first piston in the positive displacement direction continues during the entire period during which the second piston is displaced in the negative displacement direction and reaches the maximum negative displacement position of the second piston, the maximum positive displacement position of the first piston is reached as the maximum negative displacement of the second piston ends and displacement of the second piston in the positive direction begins;
- displacement of the first piston in the negative displacement direction begins during displacement of the second piston in the positive displacement direction, and the first piston reaches it maximum negative displacement position during the displacement of the second piston in the positive displacement direction; and
- wherein the control valve is a member that rotates with the cam about a common axis, and the member has a generally epsilon-shaped passageway with an arcuate back and a straight cross portion that extends toward and terminates in a terminus at the axis of rotation of the member, and the epsilon-shaped passageway is circumscribed by an annular passageway with a side-arm passageway extending from the annular passageway towards the epsilon-shaped passageway, and the side-arm passageway terminates in an arcuate passageway that is on a common circle with the arcuate back of the epsilon-shaped passageway, further wherein the annular passageway is always in fluid communication with the inlet line, and the outlet line is always in fluid communication with the arcuate back of the terminus of the cross portion of the epsilon shaped passageway, and when the control valve is in the first position the first pumping chamber passageway is in fluid communication with arcuate passageway and the second pumping chamber passageway is in fluid communication with the arcuate back of the epsilon shaped passageway, and when the control valve is in the second position the first pumping chamber passageway is in fluid communication with the arcuate back of the epsilon shaped passageway, and the second pumping chamber passageway is in fluid communication with the arcuate passageway.
- 26. The pump of claim 25 wherein the control valve is a member that rotates with the cam about a common axis, and the member has a generally epsilon-shaped passageway with an arcuate back and a straight cross portion that extends toward and terminates in a terminus at the axis of rotation of the member, and the epsilon-shaped passageway is circumscribed by an annular passageway with a side-arm passageway extending from the annular passageway towards the epsilon-shaped passageway, and the side-arm passageway terminates in an arcuate passageway that is on a common circle with the arcuate back of the epsilon-shaped passageway, further wherein the annular passageway is always in fluid communication with the inlet line, and the outlet line is always in fluid communication with the arcuate back of the terminus of the cross portion of the epsilon shaped passageway, and when the control valve is in the first position the first pumping chamber passageway is in fluid communication with arcuate passageway and the second pumping chamber passageway is in fluid communication with the arcuate back of the epsilon shaped passageway, and when the control valve is in the second position the first pumping chamber passageway is in fluid communication with the arcuate back of the epsilon shaped passageway, and the second pumping chamber passageway is in fluid communication with the arcuate passageway.
- 27. The pump of claim 26, further comprising a fluid leak return chamber formed in one of the first or second piston bores, and a fluid leak return line communicating with the fluid leak return chamber, wherein the fluid leak return chamber collects fluid that seeps out of the first or second pumping chambers, and returns the fluid to one of the first or second pumping chamber passageways.
- 28. A pump for delivery of a fluid, comprising:
- first and second reciprocating pistons, wherein the first piston communicates with a first pumping chamber, and the second piston communicates with a second pumping chamber;
- an inlet flow path that communicates with the first pumping chamber when the first piston is reciprocating in a direction that draws fluid into the first pumping chamber, and with the second pumping chamber when the second piston is reciprocating in a direction that draws fluid into the second pumping chamber;
- an outlet flow path that communicates with the first pumping chamber when the first piston is reciprocating in a direction that expels fluid out of the first pumping chamber, and with the second pumping chamber when the second piston is reciprocating in a direction that expels fluid out of the second pumping chamber;
- a control valve that alternately moves between a first position and a second position, wherein when the control valve is in the first position the inlet flow path to the first pumping chamber is continuous and the outlet flow path from the first pumping chamber is interrupted, and the inlet flow path to the second pumping chamber is interrupted and the outlet flow path from the second pumping chamber is continuous, and when the control valve is in the second position the inlet flow path to the second pumping chamber is continuous and the outlet flow path from the second pumping chamber is interrupted, and the inlet flow path to the first pumping chamber is interrupted and the outlet flow path from the first pumping chamber is continuous; and
- wherein each reciprocating piston is reciprocated by a cam having a bearing face, the cam moves the control valve between the first and second positions of the control valve, and the cam has a variable shaped surface that reciprocates the first and second pistons as the cam rotates, and the control valve comprises a control surface rotated by the cam, wherein the control surface has a plurality of grooves inscribed therein that establish passageways through which the control valve directs the flow of the fluid to establish the continuous and interrupted flow paths when the control valve is in the first and second positions; and wherein the plurality of grooves comprise:
- a first annular groove in communication with one of the inlet or outlet flow path throughout rotation of the cam;
- a second groove that is coincident with an inner circle circumscribed by the first groove;
- an indentation on the axis of rotation of the cam that, throughout rotation of the cam, is in communication with the inlet or outlet flow path that is not in communication with the first annular groove;
- wherein the second groove comprises a first groove portion and a second groove portion that are discontinuous with each other, and the first and second groove portions alternately communicate with the first and second pumping chambers as the control surface rotates;
- a first connecting groove that connects the first groove portion of the second groove with the indentation on the axis of rotation; and
- a second connecting groove that connects the second groove portion of the second groove with the first annular groove.
CROSS REFERENCE TO RELATED CASES
This is a Continuation-in-Part of U.S. patent application Ser. No. 08/406,399 filed Mar. 20, 1995 now abandoned, and U.S. patent application Ser. No. 08/407,405 also filed Mar. 20, 1995 now allowed.
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Foreign Referenced Citations (4)
Number |
Date |
Country |
0 172 780 |
Jun 1984 |
EPX |
658937 |
Mar 1938 |
DEX |
566020 |
Aug 1977 |
SUX |
768330 |
Feb 1957 |
GBX |
Related Publications (1)
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Number |
Date |
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407405 |
Mar 1995 |
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Continuation in Parts (1)
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Number |
Date |
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Parent |
406399 |
Mar 1995 |
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