U.S. patent application number 13/887490 was filed with the patent office on 2013-09-19 for uniform flow displacement pump.
This patent application is currently assigned to International Remote Imaging Systems, Inc.. The applicant listed for this patent is INTERNATIONAL REMOTE IMAGING SYSTEMS, INC.. Invention is credited to Conrad O. Diaz, John P. Pelmulder.
Application Number | 20130243631 13/887490 |
Document ID | / |
Family ID | 32326540 |
Filed Date | 2013-09-19 |
United States Patent
Application |
20130243631 |
Kind Code |
A1 |
Pelmulder; John P. ; et
al. |
September 19, 2013 |
UNIFORM FLOW DISPLACEMENT PUMP
Abstract
A displacement pump comprising a pump assembly and a cassette
assembly. The pump assembly includes upper and lower housing
portions that define a cavity, an arm disposed in the cavity, a
roller attached to the distal end of the arm, and a motor attached
to the proximal end of the arm for rotating the arm. The cassette
assembly is removably disposed in the cavity and comprises upper
and lower cassette housing portions that form an annular
compression surface with a channel therein. A hollow compression
tube having a flange extending along a length thereof is secured to
the compression surface by the flange being engaged with the
channel. As the motor rotates the roller arm, the roller presses
the compression tube against the compression surface to create a
moving occlusion of the compression tube for pushing fluid through
the compression tube.
Inventors: |
Pelmulder; John P.;
(Chatsworth, CA) ; Diaz; Conrad O.; (Canoga Park,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
INTERNATIONAL REMOTE IMAGING SYSTEMS, INC. |
Chatsworth |
CA |
US |
|
|
Assignee: |
International Remote Imaging
Systems, Inc.
Chatsworth
CA
|
Family ID: |
32326540 |
Appl. No.: |
13/887490 |
Filed: |
May 6, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11634672 |
Dec 5, 2006 |
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13887490 |
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10696804 |
Oct 29, 2003 |
7150607 |
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11634672 |
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60427468 |
Nov 18, 2002 |
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Current U.S.
Class: |
417/477.2 |
Current CPC
Class: |
F04B 43/1238 20130101;
F04B 43/12 20130101 |
Class at
Publication: |
417/477.2 |
International
Class: |
F04B 43/12 20060101
F04B043/12 |
Claims
1-13. (canceled)
14. A pump, comprising: a pump housing (20a, 20b) that defines a
cavity (26), the pump housing including a first pump housing
portion (20b) and a second pump housing portion (20a), the pump
housing portions (20a, 20b) being engageable with one another to
close the pump housing and being separable from one another to open
the pump housing; a compression surface (56) within the cavity (26)
and having a channel (58) formed therein; a hollow compression tube
(60) secured to the compression surface (56), the hollow
compression tube including a flange (62) extending along a length
thereof, and the flange (62) being removably engaged with the
channel (58) for securing the compression tube to the compression
surface; compression means (28, 29) within the cavity (26) for
incrementally compressing the compression tube (60) against the
compression surface (56) to create a moving occlusion of the
compression tube that uniformly pushes fluid through the
compression tube, wherein the compression means (28, 29) has at
least one rest position in which the compression means does not
compress the compression tube, the compression means including a
roller (29) and means (28) for moving the roller (29) relative to
the pump housing (20a, 20b) when the pump housing is closed; and a
motor (30) disposed outside the cavity (26) and drivingly engaged
with the moving means (28), characterised by a cassette housing
(46a, 46b) disposed in the cavity (26) and containing the hollow
compression tube (60), the cassette housing being shaped to define
the compression surface (56) and the said channel (58) and to be
removable together with the hollow compression tube (60) from the
cavity (26) when the pump housing (20a, 20b) is open while leaving
the moving means (28) and the roller (29) remaining in the cavity
(26), and in that the cassette housing has a lower cassette housing
portion (46b) and an upper cassette housing portion (46a) removably
attached to the lower cassette portion (46b) whereby the hollow
compression tube (60) can be secured to and released from the
cassette housing.
15. The pump of claim 14, wherein the compression surface (56) is
annularly shaped, and the moving means comprises a spring loaded
arm (26) that rotates about a fixed point.
16. The pump of claim 14, wherein the compression surface (56) is
elliptically shaped; and the moving means comprises a spring loaded
arm (28) that rotates about a fixed point.
17. The pump of claim 16, wherein as the spring loaded arm (28)
rotates through a complete revolution about the fixed point, the
roller (29) disengages from the compression tube (60) at least
twice.
18. The pump of claim 14, wherein the compression means has a
plurality of rollers that roll along the compression tube, and no
more than one of the plurality of rollers compresses the
compression tube at any given time.
19. The pump of claim 14, wherein the flange (58) is tube shaped
and integrally formed with the compression tube (60).
20. The pump of claim 1, wherein the compression means includes a
second rest position in which the compression means forms a
temporary pinch-valve by temporarily stalling the moving occlusion
of the compression tube.
21. The pump of claim 14, wherein the moving means includes an arm
(28) having a proximal end and a distal end, wherein the roller
(29) is attached to the distal end of the arm (28) and the motor
(30) is drivingly engageable with the proximal end of the arm
(28).
22. The pump of claim 21, wherein the arm (28) is spring loaded for
applying pressure on the compression tube (60) by the roller
(29).
23. The pump of claim 21, wherein the arm (28) has a rest
rotational position where the roller does not contact the
compression tube.
24. The pump of claim 23, wherein the second pump housing portion
(20a) is hingedly attached to the first pump housing portion
(20b).
25. The pump of claim 23, further comprising a sensor (36) for
sensing that the second pump housing portion (20a) is positioned in
a closed position relative to the first pump housing portion
(20b).
26. The pump of claim 14, further comprising a sensor (37) for
sensing that the cassette housing (12) is disposed in the cavity
(26).
27. The pump of claim 14, wherein the lower cassette housing
portion (46b) includes an annular sidewall (50) and a shoulder (52)
extending from the annular sidewall, the upper cassette housing
portion (46a) includes an annular sidewall (54), and the annular
sidewalls (50, 54) of the lower and upper cassette housing portions
mate together to form the compression surface (58), where the upper
cassette housing portion sidewall (54) is positioned a fixed
distance away from the shoulder (53) to define the channel
(58).
28. The pump of claim 14, wherein one of the lower and upper
cassette housing portions includes tabs (48) for engaging the other
of the lower and upper cassette housing portions.
29. The pump of claim 23, wherein the arm (28) has a second rest
rotational position where the roller (29) forms a temporary
pinch-valve by temporarily stalling the moving occlusion of the
compression tube (60).
Description
[0001] This application is a continuation of U.S. Pat. No.
7,150,607, filed on Oct. 29, 2003, which claims the benefit of U.S.
Provisional Application No. 60/427,468, filed Nov. 18, 2002.
FIELD OF THE INVENTION
[0002] The present invention relates to methods and systems for
analyzing particles in a dilute fluid sample, and more particularly
to pumps utilized by such systems to manipulate the fluid
samples.
BACKGROUND OF THE INVENTION
[0003] Methods and systems for analyzing particles and particularly
sediments are well known in the art, as disclosed in U.S. Pat. Nos.
4,338,024 and 4,393,466, which are incorporated herein by
reference. Such systems utilize a flow cell though which fluid
samples are passed, and a particle analyzer for capturing still
frame images of the fluid passing through the flow cell. Thus, the
flow cell positions and presents the sample fluid containing
particles of interest for analysis. The more accurately that the
sample fluid is positioned by flow cell, the better the analysis of
the particles therein that can be made.
[0004] Typical flow cells cause the sample fluid, and a sheath
fluid that buffers the sample fluid, to flow together from a large
entry chamber into a small cross sectional examination area or
region. The transition from the inlet or entry chambers to the
examination region forms a hydrodynamic lens that squeezes both the
sample fluid and the sheath fluid proportionally into the smaller
space. Where the particles of interest are microscopic particles,
the resulting cross-sectional space occupied by the sample fluid
must be positioned within the depth of field of the analyzer, such
as an optical system or a laser system, to obtain the best
analytical information. For the best hydrodynamic focus, a large
area of sheath flow must envelop the small area of sample fluid
without any swirling or vortices. Thus, uniform flow of sample and
sheath fluids through the flow cell is essential for optimal
operation of particle analyzers.
[0005] Displacement pumps, (e.g. tubing or peristaltic pumps), are
well known in the art and have been used to pump fluid samples and
sheath fluids through flow cells. Conventional peristaltic pumps
include multiple rollers that roll along flexible tubing containing
fluid. The rollers push the fluid along the length of the tubing,
drawing fluid into an input end of the tubing and forcing fluid out
an output end of the tubing. A common configuration includes a
rotating hub with rollers on its periphery, and an annularly shaped
housing against which the tubing is pressed. With each rotation of
the hub, each roller engages with, rolls along the length of, and
disengages from, the tubing. At least one of the rollers is in
contact with the tubing at all times so that fluid cannot flow
backwards through the tubing.
[0006] Conventional peristaltic pumps have several drawbacks. For
example, multiple rollers engaging with and disengaging from the
flexible tube cause pulsations in the fluid flow through the pump,
which can be problematic for proper operation of flow cells.
Moreover, the amount of fluid delivered by the pump for n degrees
of rotation is dependent on the starting angle of the rollers. Most
pump designs only retain the tube at its ends, relying on the
multiple rollers engaged with tubing to hold it in its circular
path along the housing. Thus, the tube can stretch and contract as
the rollers move across its length, which again can cause varying
flow and uncertainty in the volume moved by rollers. Lastly, when
the pump is shut down, rollers are left in contact with the tube,
causing compression setting (flat spotting) of the tube, which
adversely affects the uniform flow of the fluid after the pump is
activated again.
[0007] There is a need for a displacement pump that provides
uniform fluid flow of known and repeatable quantities, and which
does not produce flat spots on the tube during non use.
SUMMARY OF THE INVENTION
[0008] The present invention is a pump that includes a compression
surface, a hollow compression tube secured to the compression
surface, and compression means for incrementally compressing the
compression tube against the compression surface to create a moving
occlusion of the compression tube that uniformly pushes fluid
through the compression tube, wherein the compression means has at
least one rest position in which the compression means does not
compress the compression tube.
[0009] In another aspect of the present invention, a pump includes
a pump assembly and a cassette assembly. The pump assembly includes
a pump housing that defines a cavity, a roller disposed in the
cavity, and a motor for moving the roller relative to the housing.
The cassette assembly is removably disposed in the cavity and
includes a cassette housing having a compression surface, and a
hollow compression tube secured to the compression surface. As the
motor moves the roller, the roller presses the compression tube
against the compression surface to create a moving occlusion of the
compression tube for pushing fluid through the compression
tube.
[0010] Other objects and features of the present invention will
become apparent by a review of the specification, claims and
appended figures.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1A is an exploded view of the pump assembly of the
present invention.
[0012] FIG. 1B is a perspective view of the pump assembly of the
present invention.
[0013] FIG. 2A is an exploded view of the cassette assembly of the
present invention.
[0014] FIG. 2B is a perspective view of the cassette assembly
(without compression tube) of the present invention.
[0015] FIG. 2C is a perspective view of the cassette assembly of
the present invention.
[0016] FIG. 3 is a top view of an alternate embodiment of the
present invention.
[0017] FIG. 4 is a top view of a second alternate embodiment of the
present invention.
[0018] FIG. 5 is a side view of a third alternate embodiment of the
present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0019] The uniform displacement pump of the present invention is
illustrated in FIGS. 1A-1B and 2A-2C, and includes a pump assembly
10 and a cassette assembly 12.
[0020] FIGS. 1A-1B illustrate the pump assembly 10, which includes
a housing having upper and lower housing portions 20a/20b
respectively, that are hingedly attached to each other by a hinge
22 and hinge bracket 24. When upper housing 20a is closed over
lower housing 20b, an annular cavity 26 is defined thereby. A
roller arm 28, which is preferably spring loaded, is disposed in
the cavity 26. Roller arm 28 has a proximal end at the center of
the cavity 26, and a distal end with an outwardly facing
compression roller 29 mounted thereon. A motor 30 has a drive shaft
32 that extends into the cavity 26 and is attached to the proximal
end of the roller arm 28, for rotating the roller 29 around the
periphery of the cavity 26. A sensor assembly 34 is mounted to the
lower housing 20b and includes a sensor switch 36 for detecting a
closure pin 38 from the upper housing 20a, indicating that the
upper housing 20a is in a closed position over lower housing 20b.
Sensor assembly 34 also includes a sensor switch 37 that detects
the presence of the cassette assembly 12 in cavity 26, and a sensor
40 that detects and verifies the position of the roller arm 28.
[0021] FIGS. 2A-2C illustrate the cassette assembly 12, which
includes a housing having upper and lower cassette housing portions
46a/46b respectively, that snap together via engagement tabs 48
that extend from the upper cassette housing 46a and engage with
lower cassette housing 46b. Lower cassette housing 46b includes an
annular sidewall 50 with a shoulder 52 extending from an inner
surface of the sidewall 50. Upper cassette housing 46a includes an
annular sidewall 54. When upper/lower cassette housings 46a/46b are
snapped together, upper cassette sidewall 54 fits inside lower
cassette sidewall 50, where sidewall 54 and the shoulder portion of
sidewall 50 together define an inwardly facing annular compression
surface 56. Upper cassette sidewall 54 is positioned a fixed
distance away from shoulder 52 to define a channel 58 in the
annular compression surface 56.
[0022] A hollow compression tube 60 is removably disposed along the
compression surface 56. The compression tube 60 includes a flange
62 adhered thereto or integrally formed therewith. The flange 62
snuggly inserts into channel 58 with a friction fit that evenly
secures compression tube 60 against compression surface 56.
Preferably, flange 62 is a solid cylindrically-shaped member that
is integrally formed as part of the compression tube 60, and that
has a thickness corresponding to the width of channel 58. The
compression tube 60 has an input end 60a and an output end 60b.
[0023] To assemble pump 1, upper and lower cassette housings
46a/46b are snapped together, with a compression tube 60 secured
against compression surface 56 via flange 62 (held in channel 58).
The upper pump housing 20a is rotated open (away from lower pump
housing 20b), and the cassette assembly 14 is inserted in lower
pump housing 20b. The upper pump housing 20a is then closed,
securely holding cassette assembly 12 in cavity 26.
[0024] When motor 30 is activated, roller arm 28 rotates within the
cavity 26, so that roller 29 engages with compression tube 60 and
compresses it against compression surface 56. The spring loaded
roller arm 28 ensures that roller 29 is compressed against
compression tube 60 with the desired amount of force, so that
roller 29 creates an occlusion in the compression tube 60 which
moves along the length of tube 60 as roller arm 28 makes a single
revolution within cavity 26. The moving tube occlusion pushes a
known quantity of fluid through the compression tube 60 in a
uniform manner. By the time the roller arm 28 completes its single
revolution, the roller 29 has moved along the entire length of the
compression tube portion that is disposed on compression surface
56, and has disengaged from compression tube 60. The pump shown in
the figures occludes the compression tube during (or for) 285
degrees of the rotation of roller arm 28, leaving 75 degrees of
rotation where the roller 29 does not compress tube 60.
[0025] Ideally, the diameter of the compression tube 60 is selected
so that the desired amount of fluid for a single process step (e.g.
collection of images via a flow cell) can be produced by a single
revolution of the roller arm 28, thus avoiding any pulsations
caused by the repeated engagement and disengagement of the roller
29 with compression tube 60. By continuously anchoring the
compression tube 60 against the compression surface (i.e. using the
continuous flange 62 engaged in the continuous channel 58), tube
squirm and fluid flow variations caused therefrom are avoided. A
uniform delivery of fluid volume results from each incremental
degree of rotation of roller arm 28. When the pump is inactive, the
roller 29 is preferably parked in a default or rest position shown
in FIG. 1A, where the roller 29 does not contact the compression
tube 60, thus preventing premature tube failure due to the
formation of flat spots therein. However, roller 29 can be
temporarily parked on compression tube 60 so that the (stalled)
tube occlusion acts as a temporary pinch-valve for the fluid inside
compression tube 60.
[0026] The removable cassette 12 allows for easy replacement of the
compression tubing 60 by the user. Insertion of the flange 62 into
channel 58 is convenient and provides a repeatable positioning of
the tubing 60 against compression surface 56. The tubing 60, and/or
the cassette assembly 12 in its entirety, can be replaced by the
user as tube 60 ages, ideally without the use of any tools. Closing
upper housing 20a onto lower housing 20b compresses the cassette
assembly 12 to secure compression tubing 60 and compression surface
56 in place (relative to pump assembly 10 and in particular roller
29). The clamping features of both the cassette assembly 12 and
pump assembly 10 provide repeatable and convenient assembly and
performance of the pump. The pump preferably uses tubing 60 having
a symmetrical cross-section, which permits more uniform fabrication
of the tubing and more repeatable pump performance, and is ideal
for clamping features of the cassette assembly 12.
[0027] It is to be understood that the present invention is not
limited to the embodiment(s) described above and illustrated
herein, but encompasses any and all variations falling within the
scope of the appended claims. For example, while pump housing
portions 20a/20b are shown hingedly attached, they could instead
snap together in the manner shown for cassette housing portions
46a/46b, and vice versa. Arm 28 need not necessarily be spring
loaded. Compression surface 56 need not be circular, so long as the
spring loaded roller arm 28 can maintain a desired minimal force
for compressing compression tube 60. For example, the compression
surface could be elliptical, where the rotating spring loaded
roller arm has enough longitudinal travel (along the length of arm
28) to maintain contact with the compression tube 60 with
sufficient force during the arm's revolution, as illustrated in
FIG. 3. Alternately, the amount of longitudinal travel of the
rotating arm could be more limited, where the roller 29 ceases
compression of, and even possibly loses contact with, the
compression tube at multiple points through its revolution, as
illustrated in FIG. 4. In this case, the roller 29 twice loses
contact with the compression tube 60, so that the pump produces two
separate pulses of fluid flow per full revolution of the arm 28. In
fact, roller 29 need not rotate about a fixed point, but can
include translational movement, as shown in FIG. 5. In this
embodiment, spring loaded arm 28 is connected to a moving conveyor
belt or track 64 that moves roller 29 along a planar compression
surface 56. One or more additional roller arms 28 (with rollers 29)
can be added to belt/track 64, so long as only one roller is
engaged with compression tube 60 at any given time.
* * * * *