Title:
PUMP SYSTEM WITH INTEGRATED PISTON-VALVE ACTUATION
Kind Code:
A1


Abstract:
A pump system includes a pump chamber and piston. The chamber has a cylindrical wall, an inlet port and a discharge port, both disposed in the wall axially spaced from the closed end and circumferentially spaced from each other. The piston is disposed in the pump chamber for reciprocating and rotational movement. The piston has at least one channel formed therein that is aligned with the inlet port during an intake stroke and is rotated out of alignment with the inlet port during a discharge stroke. The drive system includes a motor, a threaded shaft coupled to the motor and a coupling assembly coupling the shaft to the piston. The coupling assembly is configured to linearly move the piston when the piston is rotationally constrained and to rotationally move the piston when the piston is linearly constrained.



Inventors:
Breidenbach, Thomas S. (Maple Grove, MN, US)
Application Number:
11/670810
Publication Date:
08/07/2008
Filing Date:
02/02/2007
Assignee:
TETRA LAVAL HOLDINGS & FINANCE SA (Pully, CH)
Primary Class:
Other Classes:
53/558, 417/500
International Classes:
F04B7/06
View Patent Images:
Related US Applications:



Primary Examiner:
BERTHEAUD, PETER JOHN
Attorney, Agent or Firm:
THOMAS SCOTT BREIDENBACH (MAPLE GROVE, MN, US)
Claims:
What is claimed is:

1. A pump system comprising: a pump chamber having a cylindrical wall having a length and a closed end, an inlet port disposed in the wall axially spaced from the closed end and a discharge port disposed in the wall axially spaced from the closed end and circumferentially spaced from the inlet port; a piston disposed in the pump chamber and configured for reciprocating movement and rotational movement, the piston having a channel formed therein, the channel extending generally axially from an end thereof, the channel being aligned with the inlet port during an intake stroke and being aligned with the discharge port during a discharge stroke; a drive system including a motor and a threaded shaft and a coupling assembly coupling the motor to the piston, the coupling assembly configured to linearly move the piston when the piston is rotationally constrained and to rotationally move the piston when the piston is linearly constrained; means for selectively linearly restraining the piston to effect rotational movement of the piston; and means for selectively rotationally retraining the piston to effect linear movement of the piston.

2. The pump system in accordance with claim 1 wherein the threaded shaft is mounted to the motor and the coupling assembly is disposed at the piston.

3. The pump system in accordance with claim 1 wherein the pump chamber and piston are ceramic.

4. The pump system in accordance with claim 1 including a cam follower operably connected to the piston.

5. The pump system in accordance with claim 4 wherein the means for selectively rotationally restraining the piston includes a track defining a linear path, and wherein the cam follower moves in the track and is restrained from rotational movement by the track.

6. The pump system in accordance with claim 1 wherein the means for selectively linearly restraining the piston includes a rotating ring at an end of one of the intake stroke and the discharge stroke, the rotating ring receiving the cam follower, the cam follower rotating with the ring and restrained from linear movement by the ring.

7. The pump system in accordance with claim 6 including a ring at the end of the intake stroke and a ring at the end of the discharge stroke.

8. The pump system in accordance with claim 7 including rings at the end of the intake stroke and at the end of the discharge stroke.

9. The pump system in accordance with claim 6 including two cam followers circumferentially spaced 180 degrees apart, and wherein the rotating ring includes two recesses circumferentially spaced 180 degrees to receive the cam followers when the piston is at the end of the intake or discharge stroke.

10. The pump system in accordance with claim 7 including two cam followers circumferentially spaced 180 degrees apart, and wherein the rotating rings each include two recesses circumferentially spaced 180 degrees to receive the cam followers when the piston is at the end of the intake and discharge strokes, respectively, and wherein the means for selectively rotationally restraining the piston includes a track defining a linear path and extending between the rings, and wherein the cam follower moves in the track and is restrained from rotational movement by the track.

11. The pump system in accordance with claim 10 wherein the track is a first track, and including a second track parallel to the first track, the first and second tracks configured to receive the cam followers and to restrain the cam followers from rotational movement.

12. The pump system in accordance with claim 8 including a one-way clutch associated with each of the rings, the one-way clutches permitting the rings to rotate in opposite directions.

13. The pump system in accordance with claim 1 wherein the drive system coupling assembly is a ball screw.

14. A pump system comprising: a pump chamber having a cylindrical wall having a length and a closed end, the chamber having an inlet port disposed in the wall axially spaced from the closed end and a discharge port disposed in the wall axially spaced from the closed end, the inlet and discharge ports spaced about equally from the closed end and circumferentially spaced from one another; a piston disposed in the pump chamber and configured for reciprocating movement and rotational movement, the piston having a channel formed therein, the channel extending generally axially from an end thereof to a termination along a length of the piston, the channel being aligned with the inlet port during an intake stroke and aligned with the discharge port during a discharge stroke, the piston reciprocating such that the channel termination is about aligned with the inlet or discharge port when the piston is at the end of the discharge stroke; a drive system including a motor and a threaded shaft coupled to the motor, the drive system including a screw coupling assembly disposed at the piston coupling the threaded shaft to the piston, the coupling configured to linearly and rotationally move the piston; a cam follower operably connected to the piston; a linear track configured to receive the cam follower as the piston moves between the end of the discharge stroke and the end of the intake stroke; and first and second one-way rotating cam receiving elements disposed at opposing ends of the tracks to engage the cam follower when the piston is at the end of the discharge and intake strokes, respectively, the one-way rotating cam receiving elements rotating in opposite directions, wherein when the piston is at the end of the discharge stroke with the piston channel aligned with the discharge port, the motor rotates and the first one-way rotating cam receiving element permits rotational movement of the piston to align the channel with the inlet port, the motor reverses direction and the first one-way rotating cam receiving element prevents reverse rotational movement and the screw coupling permits linear movement of the piston with the cam follower in the linear track, the piston withdrawing from the pump chamber until the cam follower engages the second one-way rotating cam receiving element to stop linear movement and translate movement to rotational movement to rotate the piston and align the channel with the discharge port, the motor reversing direction and the second one-way rotating cam receiving element prevents rotational movement and screw coupling permits linear movement of the piston with the cam follower in the linear track, the piston inserting into the pump chamber until the cam follower engages the first one-way rotating cam receiving element.

15. The pump system in accordance with claim 14 wherein the pump chamber and piston are ceramic.

16. The pump system in accordance with claim 14 including two cam followers circumferentially spaced 180 degrees apart, and wherein the rotating cam receiving elements each include two recesses circumferentially spaced 180 degrees to receive the cam followers when the piston is at the end of the intake and discharge strokes, respectively.

17. The pump system in accordance with claim 16 including two linear tracks defining parallel to one another and circumferentially spaced from one another, the linear tracks extending between the rotating cam receiving elements, and wherein the cam followers move in the tracks and are restrained from rotational movement by the tracks.

18. The pump system in accordance with claim 14 wherein the pump is seal-less.

19. A pump system comprising: a pump chamber having a cylindrical wall having a length and a closed end, an inlet port disposed in the wall axially spaced from the closed end and a discharge port disposed in the wall axially spaced from the closed end and circumferentially spaced from the inlet port; a piston disposed in the pump chamber, the piston configured to reciprocate and rotate within the chamber, the piston having an inlet channel formed therein for cooperating with the inlet port and a discharge channel formed therein for cooperating with the discharge port, the channels each extending in a curved profile from a common end of the piston, the inlet channel being aligned with the inlet port during an intake stroke and the discharge channel being aligned with the discharge port during a discharge stroke, the inlet port and discharge port and inlet channel and discharge channel are positioned such that only one port can be aligned with its respective channel at a time; and a drive system including a motor operably coupled to the piston, the motor configured to reciprocate the piston within the cylinder to effect inlet or discharge and to rotate the piston between aligning the inlet port with the inlet channel during an inlet portion of a pump cycle and aligning the discharge port with the discharge channel during a discharge portion of the pump cycle.

20. The pump system in accordance with claim 19 wherein the piston resides in the pump chamber without a seal therebetween.

21. The pump system in accordance with claim 19 wherein including a cam follower operably mounted to the piston and a track defining a cam surface for guiding the cam follower.

22. The pump system in accordance with claim 21 wherein the track has a substantially oval shape.

23. The pump system in accordance with claim 22 wherein the oval has substantially flattened ends.

24. The pump system in accordance with claim 19 wherein during a transition between the intake stroke and the discharge stroke and during a transition between the discharge stroke and the intake stroke, the piston is constrained from reciprocating and substantially only rotates.

25. The pump system in accordance with claim 19 wherein the inlet and discharge ports are disposed at an angle relative to one another greater than zero degrees and less than or equal to 180 degrees.

26. A pump system comprising: a pump chamber; an inlet port disposed in a wall of the pump chamber and a discharge port disposed in the wall of the pump chamber spaced from the inlet port; a piston disposed in the pump chamber and configured for reciprocating movement and rotational movement, the piston having a channel formed therein aligned with the inlet port during an intake stroke and being rotated out of alignment with the inlet port during a discharge stroke; a drive system including a single motor operably coupled to the piston to linearly move the piston in the intake and discharge strokes and to rotate the piston to align the channel and inlet port during an intake stroke and to rotate the channel out of alignment with the inlet port during a discharge stroke.

27. The pump system in accordance with claim 26 wherein the piston channel is in alignment with the discharge port during the discharge stroke.

28. The pump system in accordance with claim 26 wherein the piston channel is an inlet channel and wherein the piston includes a discharge channel that is in alignment with the discharge port during the discharge stroke.

29. A form, fill and seal packaging machine of the type for forming, filling and sealing a package, comprising: a pump system having a ceramic pump chamber having a cylindrical wall having a length and a closed end, the pump chamber having an inlet port disposed in the wall axially spaced from the closed end and a discharge port disposed in the wall axially spaced from the closed end and circumferentially spaced from the inlet port, the pump system including a ceramic piston disposed in the pump chamber and configured for reciprocating movement and rotational movement, the piston having a channel formed therein, the channel extending generally axially from an end thereof, the channel being aligned with the inlet port during an intake stroke and being out of alignment with the discharge port during the inlet stroke, the pump system further including a drive system including a motor and a threaded shaft coupled to the motor, the drive system including a coupling assembly coupling the threaded shaft to the piston, the coupling assembly configured to linearly move the piston when the piston is rotationally constrained and to rotationally move the piston when the piston is linearly constrained, the pump system having means for selectively linearly restraining the piston to effect rotational movement of the piston and means for selectively rotationally retraining the piston to effect linear movement of the piston.

30. The form, fill and seal packaging machine in accordance with claim 29 wherein the piston includes a cam follower mounted thereto and wherein the means for selectively rotationally restraining the piston includes a track defining a linear path, and wherein the cam follower moves in the track and is restrained from rotational movement by the track.

31. The form, fill and seal packaging machine in accordance with claim 30 wherein the means for selectively linearly restraining the piston includes a rotating ring at an end of the intake stroke and the discharge stroke, the rotating rings receiving the cam follower, the rotating rings being rotating in one direction only and rotating in opposite directions from one another, the cam follower rotating with the rings and restrained from linear movement by the ring.

32. The form, fill and seal packaging machine in accordance with claim 29 wherein the drive system coupling assembly is a ball screw.

33. The form, fill and seal packaging machine in accordance with claim 29 wherein the pump is seal-less.

34. The form, fill and seal packaging machine in accordance with claim 29 wherein the piston channel is in alignment with the discharge port during the discharge stroke.

35. The form, fill and seal packaging machine in accordance with claim 29 wherein the piston channel is an inlet channel and wherein the piston includes a discharge channel that is in alignment with the discharge port during the discharge stroke.

Description:

BACKGROUND OF THE INVENTION

This invention is directed to a pump system. More specifically, the invention pertains to a piston pump system that integrates valve actuation with a reciprocating and rotating pump piston.

Pump systems are well known and are available in a wide variety and array of sizes, types and designs. Piston pumps are often used in the food packaging industry and in particular in liquid food packaging because of the controllable nature of the pumping action and the precision in volumetric transport. Typically, piston pumps use a reciprocating action to intake or draw fluid into the cylinder or chamber and to discharge or exhaust fluid from the chamber.

In order to assure the hygienic standards of the process and the food product are met, the piston is typically separated from the food product by a flexible diaphragm. The diaphragm is sealed at its periphery (generally by a bead) to a structural element of the pump and extends over the head of the piston. In this manner, the food-contacting side of the piston is isolated from the driving side of the piston by the diaphragm. In use, the diaphragm is stretched and relaxed with the reciprocating action of the pump.

Although such diaphragm-containing piston pumps function well to maintain isolation of the food product from the mechanical or electro-mechanical components of the pump system, the nature of the diaphragm material and the reciprocating action of the piston (this stretching and relaxing the diaphragm) result in increased maintenance of the pump system and monitoring of the integrity of the diaphragm. Examples of such diaphragm-type pumps are disclosed in Warne et al, U.S. Pat. No. 6,871,577 and Kaneko, U.S. Pat. No. 5,897,304, both of which are commonly assigned with the present invention and are incorporated herein by reference.

Precise, dosing pumps are also known. Such pumps are more often used in the pharmaceutical industry where extreme precision over the quantity of dosing or transport of the materials is needed. The pumps also use a reciprocating movement to effect the action of piston to move the product. Some of these pumps use a seal-less design.

In order to effect the seal-less design, the pump piston and chamber are made from a ceramic material. These materials are generally able to withstand fairly aggressive environments and maintain their characteristics and integrity.

These pumps systems are also configured with inlet and discharge valves integral with the piston and chamber. In such a design, the piston rotates as well as reciprocates to align a channel or recess in the piston with an inlet or discharge opening in the chamber (cylinder) wall. The drive systems for such arrangements are complex, and require one driver for the reciprocating movement and another for the rotational movement.

Accordingly, there is a need for a pump system with integrated piston-valve actuation. Desirably, such a pump system is seal-less and provides precise control of product volume to be pumped. Most desirably, such a system uses a single piston in both reciprocating and rotational movements to effect fluid transport. Most desirably, such a pump system uses a single driver to provide both the reciprocating and the rotational movement profiles.

BRIEF SUMMARY OF THE INVENTION

A pump system is configured for use in a form, fill and seal packaging machine. The pump system includes a pump chamber having a cylindrical wall having a length and a closed end. The chamber includes an inlet port disposed in the wall axially spaced from the closed end and a discharge port disposed in the wall axially spaced from the closed end and circumferentially spaced from the inlet port. The chamber can include multiple inlet and outlet ports. The pump can be of a seal-less design.

A piston is disposed in the pump chamber and is configured for reciprocating movement and rotational movement. The piston has a channel formed therein that extends from an end thereof. The channel is aligned with the inlet port during an intake stroke and with the discharge port during a discharge stroke.

The pump system includes a drive system including a motor, a threaded shaft coupled to the motor, and a coupling assembly, such as a ball screw, that couples the motor to the piston. In a present assembly, the shaft is coupled to the motor and the ball screw is mounted to the piston. The coupling assembly is configured to linearly move the piston when the piston is rotationally constrained or held and to rotationally move the piston when the piston is linearly constrained or held.

The pump system includes means for selectively linearly restraining the piston to effect rotational movement of the piston and means for selectively rotationally retraining the piston to effect linear movement of the piston.

In a present system, a cam follower is operably connected to the piston. In this system, the means for selectively rotationally holding the piston includes a track that defines a linear path and the cam follower moves in the track and is restrained from (or prevented from) rotational movement by the track. The means for selectively linearly restraining the piston includes rotating rings at the end of the intake stroke and the discharge stroke. The rotating rings receive the cam follower and rotate (in one direction only) with the cam follower. The cam follower, and thus the piston, are restrained from linear movement when rotating in that direction by the ring. When the motor reverses and the piston is restrained from rotational movement by the ring, it then moves linearly in the track.

In a present arrangement, two cam followers are circumferentially spaced 180 degrees apart and the rotating rings each include two recesses circumferentially spaced 180 degrees to receive the cam followers when the piston is at the end of the intake or discharge stroke, respectively. In this arrangement, a second track is disposed parallel to the first track so that both cam followers are received in tracks and are restrained from rotational movement. The tracks extend between the rings, so that the cam followers are either in the ring recesses or in the tracks.

One-way clutches are associated with each of the rings to permit only one-way rotation of the rings. In the present arrangement, the one-way clutches permit the rings to rotate in opposite directions.

In an alternate embodiment, the pump system includes a pump chamber having a cylindrical wall having a length and a closed end, an inlet port disposed in the wall axially spaced from the closed end and a discharge port disposed in the wall axially spaced from the closed end and circumferentially spaced from the inlet port. The piston is disposed in the pump chamber and is configured to reciprocate and rotate within the chamber.

The piston has an inlet channel formed therein for cooperating with the inlet port and a discharge channel formed therein for cooperating with the discharge port. The channels each extend in a curved profile from a common end of the piston. The inlet channel is aligned with the inlet port during an intake stroke and the discharge channel is aligned with the discharge port during a discharge stroke. The inlet port and discharge port and inlet channel and discharge channel are positioned such that only one port can be aligned with its respective channel at a time.

A drive system includes a motor operably coupled to the piston. The motor is configured to reciprocate the piston within the cylinder to effect inlet or discharge and to rotate the piston between aligning the inlet port with the inlet channel during an inlet portion of a pump cycle and aligning the discharge port with the discharge channel during a discharge portion of the pump cycle. A single motor can be used to effect both reciprocating and rotational motion of the piston.

The reciprocating and rotating profiles are guided by a cam follower operably mounted to the piston and a track defining a cam surface for guiding the cam follower. The track has a substantially oval shape with flattened ends. In this manner during a transition between the intake stroke and the discharge stroke and during a transition between the discharge stroke and the intake stroke, the piston is constrained from reciprocating and substantially only rotates.

In a present alternate embodiment, the inlet and discharge ports are disposed at an angle relative to one another greater than zero degrees and less than or equal to 180 degrees, and preferably less than 90 degrees.

A form, fill and seal packaging machine with the present pump system is also disclosed.

These and other features and advantages of the present invention will be apparent from the following detailed description, in conjunction with the appended claims.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The benefits and advantages of the present invention will become more readily apparent to those of ordinary skill in the relevant art after reviewing the following detailed description and accompanying drawings, wherein:

FIG. 1 is a perspective view of an exemplary form, fill and seal machine having a pump system with integrated piston-valve actuation embodying the principles of the present invention;

FIG. 2 is a perspective view of a portion of the pump system showing the piston and chamber of the pump, and the ball screw and cam track and follower and one-way clutch assemblies, the pump being shown in the fully extended position, and at the beginning of the intake stroke;

FIG. 3 is a perspective view similar to FIG. 2 with the piston in the fully retracted position and at the beginning of the valve switch function;

FIG. 4 is a cross-sectional view of the pump at the beginning of the intake stroke (similar to FIG. 2);

FIG. 5 is a cross-sectional view of the pump at about mid-way through the intake stroke;

FIG. 6 is a cross-sectional view of the pump as the piston rotates at the beginning of the valve switching function to begin the discharge stroke; and

FIG. 7 is a cross-sectional view of the pump following the valve switching function (rotating from the intake orientation to the discharge orientation) and beginning into the discharge stroke to discharge fluid from the pump chamber;

FIG. 8 is a cross-sectional view of the pump about mid-way through the discharge stroke;

FIG. 9 is a cross-sectional view of the pump at the end of the discharge stroke, and as it begins to rotate (in the valve switching function) into the intake orientation;

FIG. 10 is a perspective view of an alternate embodiment of the pump system showing the piston and chamber of the pump, the pump being shown in the valve switching function, between the end of the discharge stroke and the beginning of the intake stroke, the drive system not being shown for clarity of illustration;

FIG. 11 is a perspective view of the pump as it is in the orientation of FIG. 10;

FIG. 12 is a perspective view of the pump as the piston rotates into the intake position to begin the intake stroke;

FIG. 13 is a perspective view of the pump about mid-way through the intake stroke;

FIG. 14 is a perspective view of the pump as the piston approaches the end of the intake stroke;

FIG. 15 is a perspective view of the pump as the piston rotates during the valve switching function, as the piston rotates into the discharge position;

FIG. 16 is a perspective view of the pump as it begins the discharge stroke;

FIG. 17 is a perspective view of the pump about mid-way through the discharge stroke; and

FIG. 18 is a perspective view of the pump at the end of the discharge stroke and just prior to moving into the valve switching function (from discharge to inlet).

DETAILED DESCRIPTION OF THE INVENTION

While the present invention is susceptible of embodiment in various forms, there is shown in the drawings and will hereinafter be described a presently preferred embodiment with the understanding that the present disclosure is to be considered an exemplification of the invention and is not intended to limit the invention to the specific embodiments illustrated.

It should be further understood that the title of this section of this specification, namely, “Detailed Description Of The Invention”, relates to a requirement of the United States Patent Office, and does not imply, nor should be inferred to limit the subject matter disclosed herein.

Referring now to the figures and in particular to FIG. 1, there is shown a form, fill and seal packaging machine 10 having a pump system with integrated piston-valve actuation 12 embodying the principles of the present invention. The form, fill and seal machine 10 is configured generally to store a series of carton blanks in a flat, folded form, erect the blanks into a tubular form, fold and seal the bottom flaps of the carton, fill and seal the cartons as they move through the machine 10. The form, fill and seal packaging machine 10 can be such as that disclosed in Katsumata, U.S. Pat. No. 6,012,267, which patent is assigned to the assignee of the present invention and is incorporated herein by reference.

To effect the form, fill and seal process, the packaging machine 10 includes a carton magazine 14 for storing the flat, folded carton blanks, a carton erection station 16 and a bottom forming and sealing station 18 to erect the cartons into a tubular form and to fold and seal the carton bottom. The machine 10 typically also includes a sterilization station 20 for sterilizing the cartons and includes a filling station 22 at which the cartons are filled with product. Following the filling station 22, the carton top panels are folded and sealed at a top folding and sealing station 24. The cartons are then off loaded from the form, fill and seal packaging machine 10.

In known pumping systems, a reciprocating piston is used to draw liquid into a pump chamber through an inlet valve and to discharge liquid from the chamber through a discharge valve. Pump systems are known in which the pump is a flow through design; other types of systems use a more conventional design in which the piston is normal to the direction of flow of the liquid into and out of the pump. Regardless, the pumps employ a design in which a diaphragm separates the piston from the pumped liquid or product.

The present pump system 12 (which is located at the filling station 22) employs a piston-type pump 26. A preferred system 12 includes a pump 26 of ceramic design and can be configured to do away with rubber or other flexible seals between the piston 28 and the pump chamber 30 wall 32. Instead, the ceramic piston 28 is fitted into the chamber 30 at tolerances sufficiently small that there is minimal leakage from the chamber 30, around the piston 28. Such pumps 26 are known and are commercially available from, for example, Neoceram of Brussels, Belgium.

Referring to FIG. 2, the structure of the pump system 12 will be described, however, it will be appreciated that the pump 26 is described in general terms and that various details and the like that are not specifically shown, will be appreciated by those skilled in the art. The pump system 12 includes generally the piston 28, the pump cylinder or chamber 30 and a drive 34. The system 12 further includes a lead screw, linear ball screw or roller screw 36, a cam follower track system 38 and a pair of one-way clutches 40a,b or other devices to permit one-way or one directional rotation of the piston 28.

The pump chamber 30 includes an inlet port 42 on one side of the chamber wall 32 and a discharge port 44 in opposing relation to (e.g., 180 degrees from) the inlet port 42. The inlet and discharge ports 42, 44 can be configured as ports in the chamber wall 32, without complex valve, seat and other components necessary for inlet and discharge valves of other food product pump system valves. The ports 42, 44 are formed in the wall 32 spaced from an end 46 of the chamber wall 32. It will be appreciated that valves can be used in lieu of, or in addition to the ports.

The piston 28 includes a longitudinal channel 48 formed part of the way in the piston 28 body. The channel 48, when aligned with a valve port 42 or 44 provides flow communication between the chamber 30 and that opening. Accordingly, when the inlet port 42 is aligned with the channel 48, the channel 48 provides flow communication between the inlet 50 and the chamber 30 and when the channel 48 is aligned with the discharge port 44, the channel 48 provides flow communication between the chamber 30 and the discharge 52. It will be appreciated that when the channel 48 is aligned with the inlet 42, the discharge port 44 is sealed and conversely, when the channel 48 is aligned with the discharge 44, the inlet port 42 is sealed, and when the channel 48 is between the inlet and discharge ports 42, 44, both ports 42, 44 are sealed.

In order to align the channel 48 with either of the ports 42 or 44, the piston 28 is rotated—this in addition to reciprocating to draw fluid into and discharge fluid from the pump chamber 30. The present pump system 12 effects both the linear motion as well as the rotational motion using a single drive 34, such as a servomotor. The rotational motion of the drive 34 is translated to linear motion by use of a ball screw 36 or like arrangement. Those skilled in the art will appreciate that the ball screw 36 includes a threaded shaft 54 (that in the present pump assembly 12 is provided as or mounted to the output shaft of the drive 34) and a ball assembly, indicated generally at 56, that includes bearing balls 58 (see, e.g., FIG. 4) that ride in the threads 60 of the shaft 54. Those skilled in the art will appreciate that the ball assembly 56 can be any of a number of designs. It will be understood that when the ball assembly 56 is constrained from rotating with the shaft 54, the shaft 54 motion will be transformed into linear motion of the assembly 56 along the shaft 54. Conversely, when the ball assembly 56 is constrained from moving linearly along the shaft 54, it will rotate with rotation of the shaft 54. It will also be understood that the ball assembly can be mounted to the motor and the shaft mounted or coupled to the piston to effect the same function.

In the present assembly 12, the ball assembly 56 is mounted to the piston 28 such that constraining the rotational motion of the piston 28 causes the piston 28 to move linearly, e.g., to reciprocate. Conversely, constraining the linear movement of the piston 28 effects rotation of the piston 28, that is, it rotates the piston 28 so that the channel 48 moves between the inlet and outlet ports 42, 44. As such, a single drive or motor 34 with a ball screw 36 provides both the linear and the rotational motions of the piston 28.

In order to constrain the piston 28 so as to effect either linear or rotational motion, the pump system 12 includes a cam follower track system, indicated generally at 38, and a pair of rings with one-way clutches 40a,b or other devices that permit one-way or one directional rotation of the piston 28. The piston 28 includes a pair of projections or fingers that serve as cam followers 62a,b that engage the clutches 40a,b and a track 64 to permit and/or constrain movement of the piston 28. The present system uses a pair of diametrically opposed cam tracks 64a,b.

As seen in FIG. 2, one of the clutches 40a is positioned at one end 66 of cam tracks 64a and 64b and the other clutch 40b is positioned at the other end 68 of the cam tracks 64a,b. The cam follower pocket (70a,b and 72a,b, see below) positions in the clutches 40a,b correspond to the fully inserted and fully withdrawn positions of the piston 28.

A cycle of the pump system 12 will be described with reference to FIGS. 4-9. Referring first, however, to FIGS. 2 and 3, the pump system 12 components will be identified to permit following the description of the cycle. In FIG. 2, the pump 26 is shown with the piston 28 in the fully inserted position, or the end of the discharge stroke. In FIG. 3, the pump 26 is shown with the piston 28 in the fully withdrawn position, or at the end of the intake stroke. Although the piston 28 has a pair of cam followers 62a,b, reference will be made to one of the followers 62a so that the description and sequence are more readily understood.

The cam follower 62a is in a recess or pocket 70a of the one-way clutch 40a (pocket 70b being 180 degrees opposite pocket 70a) and pocket 70a and track 64a are aligned with one another. Track 64b is 180 degrees opposite track 64a.

In the intake stroke (FIGS. 4 and 5), the motor 34 rotates counterclockwise. Since clutch 40a permits only clockwise rotation (rotational motion is constrained), the piston 28 begins to move rearward, toward the drive as indicated by the arrow at 74, and the cam follower 62a enters track 64a. As the piston 28 moves rearward, the inlet port 42 is open to the channel 48 and fluid is drawn into the chamber 30 from the inlet 50.

As the piston 28 nears the end of the intake stroke, the piston 28 nears the fully withdrawn position and the cam follower 62a leaves track 64a and enters pocket 72a of one-way clutch 40b (pocket 72b being 180 degrees opposite pocket 72a). There is a slight pause at the end of the linear motion (the intake stroke). Following the brief pause, the motor 34 continues to rotate counterclockwise, and in that the linear motion of the piston 28 is now constrained, the piston 28 rotates, as seen in FIG. 6, (by rotation of the one-way clutch 40b) counterclockwise to close the inlet port 42. The motor 34 rotates 180 degrees until the inlet port 42 is closed and the outlet port 44 is open. This also aligns the cam follower 62a (and pocket 72a) with track 64b.

At this point, the pump chamber 30 is filled with liquid. As seen in FIGS. 7 and 8, the pump 26 now operates in discharge and the motor 34 begins by rotating clockwise. Since one-way clutch 40b permits rotation only counterclockwise, rotational motion is constrained and the piston 28 begins to move forward (as indicated by the arrow at 76). The cam follower 62a moves from pocket 72a into track 64b (linear motion). Since the channel 48 is now aligned with the discharge port 44, liquid is discharged through the channel 48 and the outlet port 44 to the discharge 52.

As the piston 28 nears the end of the discharge stroke, the piston nears the fully inserted position and the cam follower 62a leaves track 64b and enters pocket 70b of one-way clutch 40a, and the motor 34 continues to rotate clockwise. In that linear motion of the piston 28 is now constrained (with the cam follower 62a residing in pocket 70b), the piston 28 rotates clockwise as seen in FIG. 9, (which is the direction permitted by clutch 40a) to close the discharge port 44. The motor 34 rotates 180 degree until the discharge port 44 is fully closed and the inlet port 42 is open. This also aligns the cam follower 62a (in pocket 70b) with track 64a. This completes one full cycle. It will again be appreciated that the movement of only cam follower 62a is described (understanding that there is a cam follower 62b) for ease of discussion and explanation only. Again, there is a slight pause between the end of the linear motion and the beginning of the rotational motion.

It will also be appreciated by those skilled in the art that although the description of the present system 12 refers to two cam followers 62a,b, and pockets 70a,b and 72a,b in each of the one-way clutches 40a,b, as well as to two cam tracks 64a,b, it will be readily understood that a different number of tracks 64 as well as inlet ports 42 and outlet ports 44 can be envisioned for the present pump system 12, and that such other configurations are within the scope and spirit of the present invention.

An alternate embodiment of the pump system 112 is illustrated in FIG. 10 with an operational description provided in reference to FIGS. 11-18. In this embodiment, the pump piston 128 is again driven by a single drive, such as a motor (not shown for clarity of illustration) to effect both the reciprocating and rotating motions. The system 112, like that of FIGS. 1-9 includes a threaded rod and coupling assembly (also not shown) operably connecting the motor and the piston.

The pump chamber 130 includes an inlet port 142 and an outlet port 144. The ports 142, 144 are shown at an acute angle α to one another, but, as will be appreciated from the description below and an understanding of the figures, can be at a wide variety of angles.

Unlike the previous embodiment 28, the piston 128 of this embodiment 112 includes a flow channel associated with each of the ports—that is, the piston 128 includes an inlet channel 148 associated with the inlet port 142 and a separate discharge channel 149 associated with the discharge port 144. The channels 148, 149, when aligned with their respective ports 142, 144, provide flow communication between the respective port 142 or 144 and the pump chamber 130.

The cam follower track system 138, unlike the previous embodiment, includes an oval track 164 that imparts a linear component, as indicated at 180, for pumping, and a rotational component, as indicated at 182, for valve switching, to the piston 128, rather than discrete linear and rotational tracks or elements. The track 164 includes a pair of opposing curved portions 164a,b and transitions 166a,b between the curved portions. The curved portions 164a,b correspond to the intake and discharge strokes and the transitions 166a,b correspond to the valve switching functions. The transitions 166a,b can be formed as flat areas between the curved portions 164a,b. The piston includes a cam follower 162 that rides in (or follows) the track 164 (including the transitions 166a,b)

Accordingly when the piston 128 is rotating during the valve switching functions, both the inlet port 142 and the discharge port 144 are closed to their respective channels 148, 149 (see FIG. 10). It is important to note that during the period that the ports 142, 144 are closed to the channels 148, 149, which are the valve switching functions, (e.g., there is no fluid flow into or out of the chamber 130), the piston 128 does not move in the linear (pumping or intake) directions. This is to prevent pumping against or drawing in against the closed ports 142, 144. As such, to prevent a linear component to the pump movement during the valve switching functions, the transitions 166a,b are preferably formed flat, but can be very short in length.

A brief description of a cycle of operation will be provided with reference to FIGS. 11-18. As illustrated in FIG. 11, the pump 126 is in the valve switching mode, moving from the discharge state to the intake state. The piston 128 rotates (as indicated by the arrow at 165), to align the inlet port 142 with the inlet channel 148.

The cam follower 162 then continues moving into track 164a (with both a linear component and a rotational component) to withdraw the piston 128 which draws fluid into the chamber 130 through the inlet port 142 and channel 148, as seen in FIGS. 12-14.

As the piston 128 nears the end of the inlet stroke, the cam follower 162 moves into the transition 166b between the curved track portions 164a,b. At this point in time, as seen in FIG. 15, the inlet channel 148 moves out of alignment with the inlet port 142 and the motion of the piston 128 is rotational. This provides the valve switching function, and also prevents the piston 128 attempting to draw in fluid against the now closed port 142.

The piston 128 continues to rotate to align the discharge channel 149 with the discharge port 144, and the cam follower 162 moves into the opposite curved portion 164b of the track 164 to begin the pumping (discharge) portion of the cycle, as seen in FIG. 16. The piston 128 continues to move through the discharge stroke (FIG. 17) until the cam follower 162 reaches the opposite transition portion 166a of the track 164 (FIG. 18), at which point the piston 128 rotates to move the discharge channel 149 out of alignment with the discharge port 144 and move the inlet channel 148 back into alignment with the inlet port 142 (back to FIGS. 11 and 12). It is believed that the rotational movement of the piston in either the intake or discharge stroke will provide sufficient rotational momentum to carry the piston through the valve change cycle without the piston moving back through the previously completed portion of the pumping cycle. A flywheel (not shown) or like device can be used to provide sufficient momentum to maintain the piston 128 moving in the proper direction.

It will be appreciated that although one track 164 and one cam follower 162 are described, this embodiment of the pump system 112 can include more than one track and more than one cam follower (opposite one another peripherally about the chamber 130) so as to balance the forces exerted on the piston 128. It will also be appreciated that although the oval track 164 embodiment of the pump system 112 is introduced with reference being made to the ball screw (or like) drive arrangement of the prior embodiment, it will be appreciated that the oval track 164 configuration can be used with a reciprocating drive that includes a slip coupling or other coupling member that allows a degree of rotational movement without expressly directing or imparting a rotational component to the piston movement. In this manner, the piston 128 will move rotationally as the cam follower 162 follows the oval track 164 to provide the necessary valve switching function. The slip coupling can be provided by a ball joint connection at the end of a reciprocating rod, or in other ways that will be recognized by those skilled in the art.

Another alternative configuration (not shown) includes an annular design with, however, the ports disposed in the wall of an inner annular wall.

It will also be appreciated by those skilled in the art that the present pump systems 10, 110 can be configured having variable pumping capacities or volumes, which can be discrete or continuously variable, by, for example, limiting the length of the stroke. For such a configuration in the straight track embodiment 10, the tracks could be formed from multiple shorter sections with rings located between the sections that correspond to a desired pump volume. In the oval track embodiment 110, the track could include track sections or gates that branch from the tracks at which the piston could be rotated (to align the respective channels and ports) or alternatively, multiple tracks that define a particular stroke length to facilitate the variable pump capacity.

In the present disclosure, the words “a” or “an” are to be taken to include both the singular and the plural. Conversely, any reference to plural items shall, where appropriate, include the singular.

From the foregoing it will be observed that numerous modifications and variations can be effectuated without departing from the true spirit and scope of the novel concepts of the present invention. It is to be understood that no limitation with respect to the specific embodiments illustrated is intended or should be inferred. The disclosure is intended to cover by the appended claims all such modifications as fall within the scope of the claims.