U.S. patent application number 11/670810 was filed with the patent office on 2008-08-07 for pump system with integrated piston-valve actuation.
This patent application is currently assigned to TETRA LAVAL HOLDINGS & FINANCE SA. Invention is credited to Thomas S. Breidenbach.
Application Number | 20080187449 11/670810 |
Document ID | / |
Family ID | 39676331 |
Filed Date | 2008-08-07 |
United States Patent
Application |
20080187449 |
Kind Code |
A1 |
Breidenbach; Thomas S. |
August 7, 2008 |
PUMP SYSTEM WITH INTEGRATED PISTON-VALVE ACTUATION
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) |
Correspondence
Address: |
TETRA PAK US INTELLECTUAL PROPERTY DEPARTMENT;TETRA PAK INC.
101 COPORATE WOODS PARKWAY
VERNON HILLS
IL
60061
US
|
Assignee: |
TETRA LAVAL HOLDINGS & FINANCE
SA
Pully
CH
|
Family ID: |
39676331 |
Appl. No.: |
11/670810 |
Filed: |
February 2, 2007 |
Current U.S.
Class: |
417/499 ;
417/500; 53/558 |
Current CPC
Class: |
F04B 7/06 20130101 |
Class at
Publication: |
417/499 ;
417/500; 53/558 |
International
Class: |
F04B 7/06 20060101
F04B007/06 |
Claims
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
[0001] 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.
[0002] 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.
[0003] 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.
[0004] 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.
[0005] 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.
[0006] 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.
[0007] 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.
[0008] 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
[0009] 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.
[0010] 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.
[0011] 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.
[0012] 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.
[0013] 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.
[0014] 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.
[0015] 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.
[0016] 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.
[0017] 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.
[0018] 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.
[0019] 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.
[0020] 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.
[0021] A form, fill and seal packaging machine with the present
pump system is also disclosed.
[0022] 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
[0023] 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:
[0024] 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;
[0025] 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;
[0026] 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;
[0027] FIG. 4 is a cross-sectional view of the pump at the
beginning of the intake stroke (similar to FIG. 2);
[0028] FIG. 5 is a cross-sectional view of the pump at about
mid-way through the intake stroke;
[0029] 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
[0030] 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;
[0031] FIG. 8 is a cross-sectional view of the pump about mid-way
through the discharge stroke;
[0032] 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;
[0033] 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;
[0034] FIG. 11 is a perspective view of the pump as it is in the
orientation of FIG. 10;
[0035] FIG. 12 is a perspective view of the pump as the piston
rotates into the intake position to begin the intake stroke;
[0036] FIG. 13 is a perspective view of the pump about mid-way
through the intake stroke;
[0037] FIG. 14 is a perspective view of the pump as the piston
approaches the end of the intake stroke;
[0038] 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;
[0039] FIG. 16 is a perspective view of the pump as it begins the
discharge stroke;
[0040] FIG. 17 is a perspective view of the pump about mid-way
through the discharge stroke; and
[0041] 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
[0042] 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.
[0043] 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.
[0044] 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.
[0045] 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.
[0046] 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.
[0047] 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.
[0048] 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.
[0049] 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.
[0050] 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.
[0051] 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.
[0052] 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.
[0053] 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.
[0054] 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.
[0055] 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.
[0056] 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.
[0057] 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.
[0058] 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.
[0059] 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.
[0060] 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.
[0061] 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.
[0062] 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.
[0063] The pump chamber 130 includes an inlet port 142 and an
outlet port 144. The ports 142, 144 are shown at an acute angle
.alpha. 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.
[0064] 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.
[0065] 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)
[0066] 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.
[0067] 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.
[0068] 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.
[0069] 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.
[0070] 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.
[0071] 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.
[0072] Another alternative configuration (not shown) includes an
annular design with, however, the ports disposed in the wall of an
inner annular wall.
[0073] 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.
[0074] 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.
[0075] 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.
* * * * *