U.S. patent application number 10/760765 was filed with the patent office on 2005-07-21 for highly accurate pumping device.
This patent application is currently assigned to Innovative Mechanical Designs, Inc.. Invention is credited to Autrey, Robert C..
Application Number | 20050158191 10/760765 |
Document ID | / |
Family ID | 34750063 |
Filed Date | 2005-07-21 |
United States Patent
Application |
20050158191 |
Kind Code |
A1 |
Autrey, Robert C. |
July 21, 2005 |
Highly accurate pumping device
Abstract
A highly accurate pumping device for aspirating and dispensing
variable volumes of fluid is presented. The pumping device
comprises a housing with a slotted optical sensor, a stepper motor
with a fine pitch lead screw, a coupling linking the stepper motor
shaft and the lead screw, an anti-backlash nut, an anti-rotation
arm linking the plunger with the anti-backlash nut, an end of
travel sensor feature integrated in the arm, and a top which
incorporates a chamber and a lead screw bearing. A seal, located in
the top, seals against the plunger and the chamber. The plunger is
attached to the anti-rotation arm and eccentrically aligned to the
lead screw. The pumping device further includes one or more ports
through which fluid may be introduced into or out of the chamber.
The pumping device may be easily changed to accommodate different
full-scale volume requirements due to the self-aligning
features.
Inventors: |
Autrey, Robert C.; (Lake
Villa, IL) |
Correspondence
Address: |
Robert C. Autrey
612 Red Spruce Trail
Lake Villa
IL
60046
US
|
Assignee: |
Innovative Mechanical Designs,
Inc.
Lake Villa
IL
|
Family ID: |
34750063 |
Appl. No.: |
10/760765 |
Filed: |
January 21, 2004 |
Current U.S.
Class: |
417/415 ;
417/437 |
Current CPC
Class: |
F04B 9/02 20130101; F04B
13/00 20130101; F04B 17/03 20130101 |
Class at
Publication: |
417/415 ;
417/437 |
International
Class: |
F04B 017/00; F04B
035/04 |
Claims
What is claimed:
1. A highly accurate pumping device comprising: a housing including
an integral anti-rotation groove and mounting location for a
slotted optical sensor; a first top removably coupled to said
housing; a first chamber within a portion of said first top, said
first chamber having a cone shape at one end; a first plunger
displaceable within a portion of said first chamber, which, in
combination with said first chamber, is adapted for aspirating and
dispensing; ports within said first top, said ports allowing for
the introduction of liquid into or out of said first chamber; a
coupler linking the lead screw and stepper motor shaft; a stepper
motor attached to said housing, which turns said lead screw for the
purpose of moving said first plunger into or out of said first
chamber;
2. The pumping device of claim 1 further comprising an
anti-rotation arm removably coupled to an anti-backlash nut, the
anti-rotation arm having an end of travel protrusion that interacts
with a slotted optical sensor.
3. The pumping device of claim 1 wherein said first plunger is
removably coupled to said anti-rotation arm.
4. The pumping device of claim 1 comprising a first seal disposed
around said first plunger and against a surface of a recessed area
of said first top.
5. The pumping device of claim 1 wherein one port is located
proximally to said first seal and oriented with its axis
perpendicular to the axis of said first chamber to allow incoming
fluid to clear away residual air bubbles from said first seal.
6. The pumping device of claim 1 wherein one port is located
distally from said first seal and axially aligned with said first
chamber.
7. The pumping device of claim 1 comprising an end cap disposed to
restrain said first seal in said first top.
8. The pumping device of claim 1 comprising a bearing disposed in a
hole in said first top, said bearing axially aligned with said lead
screw, through which one end of said lead screw protrudes.
9. The pumping device of claim 1 further comprising: a second
plunger having a different size than said first plunger; a second
top with a second chamber having a different size than said first
chamber; a second seal having a different size than said first
seal, said second seal disposed in recessed area in said second top
and restrained by an end cap; said second top, said second plunger
and said second seal adapted to aspirate or dispense a second
volume of liquid.
Description
BACKGROUND ON THE INVENTION
[0001] Many types of pumps are used to aspirate and dispense
fluids. Many applications require accurately dispensing small
volumes of fluid. Pumps typically are comprised of many pieces with
many stringent manufacturing requirements necessary for such
accurate aspirating and dispensing.
[0002] There is a need for a pump which is simple to manufacture
and is able to provide accurate aspiration and dispensing of a wide
range of volumes.
SUMMARY OF THE INVENTION
[0003] A highly accurate pumping device for aspirating and
dispensing fluids is presented. The pumping device is comprised of
a stepper motor, a lead screw, a coupler linking the stepper motor
shaft to the lead screw, an anti-backlash nut coupled to the lead
screw, an anti-rotation arm coupled to the anti-backlash nut, a
plunger coupled to the anti-rotation arm, a top section, an end cap
and a housing with a slot for the anti-rotation arm and mounts for
an end-of-travel sensor. The top section is comprised of a bearing
for locating one end of the lead screw, a pumping chamber, one or
more ports and a recessed area for a seal, which seals against the
plunger and the sides of the recessed area. The end cap is located
such as to retain the seal in the recessed area of the top section.
Activation of the stepper motor causes the plunger to move axially
into or out of the pumping chamber thus dispensing or aspirating
fluid. Accurate aspiration and dispensing of fluids is accomplished
with the use of the anti-rotation slot, the anti-backlash nut and
by adjusting several factors such as the pitch of the lead screw,
the diameter of the plunger and the actuation of the stepper motor.
Exchanging a minimal number of parts allows the pump to aspirate
and dispense different volumes of fluids. The self-aligning
features of the pump allow the pump to be easily reconfigured.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] FIG. 1A is a front perspective view of the pumping
device.
[0005] FIG. 1B is a rear perspective view of the pumping
device.
[0006] FIG. 2 is a cross sectional view of the pumping device of
FIG. 1A.
[0007] FIG. 3A is a perspective view of a first top.
[0008] FIG. 3B is a cross sectional side view of a first top in
FIG. 3A showing a bearing, a seal and the end cap.
[0009] FIG. 3C is a cross sectional view of a second top without
the bearing, seal and end cap.
[0010] FIG. 4 is a perspective view of the end cap.
[0011] FIG. 5A is a perspective view of the housing.
[0012] FIG. 5B is a cross sectional side view of the housing in
FIG. 5A.
[0013] FIG. 5C is a rear view of the housing in FIG. 5A.
[0014] FIG. 6 is a perspective view of the anti-rotation arm.
[0015] FIG. 7 is a perspective view of the anti-backlash nut, lead
screw, anti-rotation arm and a first plunger assembly.
[0016] FIG. 8A is a cross sectional view of a first plunger in FIG.
7.
[0017] FIG. 8B is a cross sectional view of a second plunger.
[0018] FIG. 9 is a perspective view of the coupler.
[0019] FIG. 10 is a perspective view of the lead screw.
[0020] FIG. 11 is a perspective view of the lead screw,
anti-backlash nut, plunger, anti-rotation arm and coupler
assembly.
[0021] FIG. 12A is a perspective view of a first seal.
[0022] FIG. 12B is a perspective view of a second seal.
[0023] FIG. 13 is a perspective view of the stepper motor.
[0024] FIG. 14 is a perspective view of the lead screw,
anti-backlash nut, anti-rotation arm, plunger, coupler and stepper
motor assembly.
DETAILED DESCRIPTION OF THE INVENTION
[0025] Shown in FIGS. 1A and 1B is a highly accurate pumping device
comprised of a first top section 1, an end cap 17, a housing 7, a
first plunger 18, an anti-rotation arm 6, a sensor 8 and a stepper
motor 10. Also shown in FIG. 1A are an inlet port 12 and an outlet
port 13. The number and location of the ports can vary. An
adjustment knob 45 is attached to the motor 10 to manually adjust
the position of the first plunger 18.
[0026] As shown in FIG. 2 the coupler 9 connects the shaft 11 of
the stepper motor 10 to the lead screw 4. The lead screw 4 is
located in a first top section 1 by means of a bearing 3. The
anti-rotation arm 6 is connected to the anti-backlash nut 5, which
moves axially along the lead screw 4 when the stepper motor 10 is
activated. A first plunger 18 is attached to the arm 6 by means of
a screw 29. A first seal 14 is retained in a first top section 1 by
means of an end cap 17. A first plunger 18 is moved axially through
a first seal 14 when the stepper motor 10 is activated. A sensor 8
located on the housing 7 is used for determining position of a
first plunger 18. The number and location of the sensor 8 on the
housing may vary. The adjustment knob 45 is attached on the motor
10 distally from the housing 7.
[0027] FIG. 3A shows a first top section 1 with a plurality of
holes 38 used to attach the top section 1 to the housing as
described below.
[0028] FIG. 3B shows the configuration of a first top section 1.
The bearing 3, which locates the lead screw as described above, is
located in a hole 34. A first seal 14 is located in a recessed area
16. The end cap 17 is attached to the top section 1 such that its
central hole, as described below, is axially aligned with a first
chamber 31 and attached to the top section 1. The end cap 17
retains the seal 14 in the recessed area 16. An outlet port 13 is
located at the top surface of the top section 1 and is axially
aligned with a first chamber 31. The chamber is substantially
cylindrical in shape. A conical section 33 of a first chamber 31
assists in removal of air bubbles when liquid is dispensed. The
inlet port 12 is located above the seal 14 perpendicular to the
chamber 31 to assist in removal of air bubbles from around the seal
14 when liquid is aspirated. A recessed area 23 is used to axially
align the top section 1 with the housing as described below.
[0029] A second top section 2 is shown in FIG. 3C. A second chamber
32 allows for a different volume to be aspirated or dispensed. The
chamber is substantially cylindrical in shape. A second seal, as
described below, is located in a second hole 44. The outlet port 13
is axially aligned with the second chamber 32. A conical section 42
of the second chamber 32 assists in removal of air bubbles when
liquid is dispensed. A hole 34 is used to locate a bearing as
described above. A recessed area 23 is used to axially align the
second top section 2 with the housing as described below. The inlet
port 12 is located perpendicular to the chamber 31 to assist in
removal of air bubbles from around the seal when liquid is
aspirated as described above.
[0030] The end cap 17, shown in FIG. 4, is comprised of a central
hole 41 and a plurality of holes 40 used to attach the end cap 17
to the top section. The central hole 41 is axially aligned with the
chamber in the top section as described above.
[0031] FIG. 5A shows the housing 7 with a plurality of holes 39
which are used to attach the housing 7 to the top section as
described above. The boss 22 is used to axially align the housing 7
with the top section as described above. A slot 25 is provided for
movement of the end of travel protrusion of the anti-rotational arm
as described below. A second slot 24 prevents the anti-rotation arm
from rotating as described below. A plurality of holes 43 is used
to attach the housing to the stepper motor as described below.
[0032] FIG. 5B shows the housing 7, which includes a boss 22 used
to axially align the housing 7 with the top section as described
above. A recessed area 21 is used to axially align the housing 7
with the stepper motor as described below.
[0033] A rear view of the housing 7 is shown in FIG. 5C. Mounting
supports 26 and a slot 30 allow for the attachment of the sensor as
described above.
[0034] The anti-rotation arm 6 is shown in FIG. 6. It contains a
protrusion 37 which is used with the sensor to indicate position of
the plunger as described above. A hole 46 is used to attach the
plunger as described below to the anti-rotation arm 6.
[0035] FIG. 7 shows the assembly of the lead screw 4, the
anti-backlash nut 5, the anti-rotation arm 6 and a first plunger
18.
[0036] FIG. 8A shows a first plunger 18 with a threaded hole 35
used to attach the plunger to the anti-rotational arm as described
above. The plunger may be attached to the anti-rotation arm by
means other than screws.
[0037] FIG. 8B shows a second plunger 19 with a diameter different
from that of the first plunger. A threaded hole 35 is used to
attach the plunger to the anti-rotation arm as described above. The
plunger may be attached to the anti-rotation arm by means other
than screws.
[0038] FIG. 9 shows one version of a coupler 9 that is used to
connect the shaft of the stepper motor to the lead screw as
described above. Other configurations of the coupler are
possible.
[0039] FIG. 10 shows the lead screw 4. The proximal end 28 is
connected to the coupler as described above. The distal end 27 is
inserted into the bearing as described above. The proximal end 28
and the distal end 27 may be of same or different diameters.
[0040] FIG. 11 shows an assembly consisting of the lead screw 4,
the anti-backlash nut 5, the anti-rotation arm 6, a first plunger
18 and the coupler 9. The anti-backlash nut is self-adjusting to
take out any backlash between the lead screw and the motor.
[0041] A first seal 14 is shown in FIG. 12A. The seal is a u-cup
shape with an internal diameter sized for the first plunger. The
outer diameter seals against the recessed area of the top section
as described above.
[0042] A second seal 15 is shown in FIG. 12B. The seal is a u-cup
shape with an internal diameter sized for the second plunger. The
outer diameter seals against the recessed area of the top section
as described above.
[0043] The stepper motor 10 is shown in FIG. 13. A boss 20 on the
motor is used to axially align the motor to the housing as
described above. A wiring connector 36 provides for power to the
motor.
[0044] FIG. 14 shows the arrangement between the stepper motor 10,
the coupler 9, the lead screw 4, the anti-backlash nut 5, the
anti-rotation arm 6 and a first plunger 18. The stepper motor 10
turns the coupler 9 which in turn rotates the lead screw 4. The
anti-backlash nut 5 travels axially along the lead screw 4. The
anti-rotation arm 6, connected to the anti-backlash nut 5, moves
with the anti-backlash nut 5. The slot in the housing described
above prevents the anti-rotation arm 6 from rotating as the lead
screw 4 is rotated. Thus, the plunger 18 is moved in an axial
direction into and out of the chamber to dispense and aspirate
fluids as described above.
[0045] The above described pumping device, using the anti-rotation
arm, the anti-rotation slot of the housing, the anti-backlash nut
with appropriate modifications to the lead screw pitch, plunger
diameter and stepper motor control and other features, provides
accurate and reliable aspiration and dispensing volumes. The
self-aligning features allow the pump to be easily reconfigured to
accommodate different full stroke volumes. The self-aligning
features, together with the few number of parts, provide for
substantial cost savings in the manufacture of the pumping
device.
[0046] Having described preferred embodiments of the invention, it
will become apparent to those of reasonable skill in the art that
other embodiments incorporating the above described features may
also be developed. Accordingly, it is submitted that the present
invention not be limited to the described embodiments but rather by
the scope and spirit of the appended claims.
* * * * *