U.S. patent application number 11/010858 was filed with the patent office on 2006-06-15 for reciprocating pump system.
This patent application is currently assigned to Hamilton Sundstrand Corporation. Invention is credited to Richard W. Caddell.
Application Number | 20060127252 11/010858 |
Document ID | / |
Family ID | 36096106 |
Filed Date | 2006-06-15 |
United States Patent
Application |
20060127252 |
Kind Code |
A1 |
Caddell; Richard W. |
June 15, 2006 |
Reciprocating pump system
Abstract
A reciprocating pump assembly includes a linear electric motor
having a cylinder, a rotor, and a stator. A multiple of check
valves are located near each end of the cylinder. Pairs of check
valves are mounted within a T-shaped fitting which permit each
fitting to operate alternatively as an inlet and a discharge
depending on the direction of the rotor stroke. Another pump
assembly utilizes the rotor to separately drive pistons through
pushrods.
Inventors: |
Caddell; Richard W.; (Otis,
IN) |
Correspondence
Address: |
CARLSON, GASKEY & OLDS, P.C.
400 WEST MAPLE ROAD
SUITE 350
BIRMINGHAM
MI
48009
US
|
Assignee: |
Hamilton Sundstrand
Corporation
|
Family ID: |
36096106 |
Appl. No.: |
11/010858 |
Filed: |
December 13, 2004 |
Current U.S.
Class: |
417/418 |
Current CPC
Class: |
H02K 33/00 20130101;
F04B 17/044 20130101; H02K 41/025 20130101; F04B 35/045
20130101 |
Class at
Publication: |
417/418 |
International
Class: |
F04B 17/04 20060101
F04B017/04 |
Claims
1. A reciprocating pump assembly comprising: a cylinder which
defines a longitudinal axis; a first check valve mounted adjacent a
first cylinder end; a second check valve mounted adjacent said
first cylinder end, said second check valve checking a flow from
said cylinder in a direction opposite than said first check valve;
a third check valve mounted adjacent a second cylinder end; a
fourth check valve mounted adjacent said second cylinder end, said
fourth check valve checking a flow from said cylinder in a
direction opposite than said third check valve; a rotor mounted
within said cylinder; and a stator mounted about said cylinder to
reciprocally drive said rotor along said longitudinal axis.
2. The reciprocating pump assembly as recited in claim 1, wherein
said first check valve, said second check valve, said third check
valve and said fourth check valve are reed valves.
3. The reciprocating pump assembly as recited in claim 1, wherein
said rotor includes an iron core with alternating bands of copper
and iron mounted onto said iron core.
4. The reciprocating pump assembly as recited in claim 1, further
comprising a seal mounted near each end of said rotor.
5. The reciprocating pump assembly as recited in claim 1, wherein
said stator includes a multiple of cooling fins interspersed
between a multiple of magnets.
6. The reciprocating pump assembly as recited in claim 5, further
comprising a tie bar which axially retains said multiple of cooling
fins and said multiple of magnets.
7. The reciprocating pump assembly as recited in claim 1, further
comprising a controller to control movement of said rotor within
said stator.
8. The reciprocating pump assembly as recited in claim 7, wherein
said controller includes a variable speed controller.
9. The reciprocating pump assembly as recited in claim 7, wherein
said controller includes a switched reluctance speed
controller.
10. The reciprocating pump assembly as recited in claim 1, wherein
said first check valve and said second check valve are contained
within a first fitting and said third check valve and said fourth
check valve are contained within a second fitting.
11. The reciprocating pump assembly as recited in claim 10, wherein
said first fitting and said second fitting are T-shaped
fittings.
12. The reciprocating pump assembly as recited in claim 1, wherein
said first check valve and said second check valve are opposed
within a first fitting and said third check valves and said fourth
check valve are opposed within a second fitting.
13. A reciprocating pump assembly comprising: a cylinder which
defines a longitudinal axis; a rotor mounted within said cylinder;
a first piston cylinder; a first piston mounted within said first
piston cylinder; a first push rod mounted to said first piston and
said rotor to drive said first piston along said longitudinal axis
in response to movement of said rotor; a first check valve mounted
to said first piston cylinder; a second check valve mounted to said
first piston cylinder, said second check valve checking a flow from
said first piston cylinder in a direction opposite than said first
check valve; a second piston cylinder; a second piston mounted
within said second piston cylinder; a second push rod mounted to
said second piston and said rotor to drive said second piston along
said longitudinal axis in response to movement of said rotor; a
third check valve mounted to said second piston cylinder; a fourth
check valve mounted to said second piston cylinder, said fourth
check valve checking a flow from said second piston cylinder in a
direction opposite than said third check valve; and a stator
mounted about said cylinder to reciprocally drive said rotor along
said longitudinal axis.
14. The reciprocating pump assembly as recited in claim 13, wherein
said first check valve and said second check valve are reed
valves.
15. The reciprocating pump assembly as recited in claim 13, wherein
said first check valve and said second check valve are located
within an end plate of said piston cylinder.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a pump, and more
particularly to a linear electric motor driven reciprocating
pump.
[0002] Reciprocating pumps/compressors are highly desirable for use
in numerous applications, particularly in environments where liquid
flow rate is relatively low and the required liquid pressure rise
is relatively high. For applications requiring less pressure rise
and greater flow rate, single stage centrifugal pumps may be
favored because of their simplicity, low cost and low maintenance
requirements. However, reciprocating pumps have a higher
thermodynamic efficiency than centrifugal pumps by as much as 10%
to 30%.
[0003] One conventional reciprocating pump utilizes a solenoid to
drive a piston within a cylinder. When the solenoid is energized
the solenoid plunger pushes air out of the discharge. When the
solenoid is de-energized a solenoid spring drives the solenoid
plunger in an opposite direction drawing air into an inlet.
Disadvantageously, a solenoid driven reciprocating pump provides
the least force at the extremes of the solenoid plunger travel. The
pull on the solenoid plunger increases by the inverse square of the
distance between the center of the plunger and the center of the
magnet such that the force across the length of travel is
uneven.
[0004] A typical air compressor load increases almost linearly as
the piston moves to compress the air. In a typical pump application
the load is generally constant along the length of travel. In
either application, the force delivered by the solenoid plunger
does not match the required load, which renders the solenoid pump
relatively inefficient. Furthermore, solenoids have relatively
limited linear travel which further increases the inherent
inefficiencies thereof.
[0005] Accordingly, it is desirable to provide a reciprocating pump
which generally matches the required load to provide efficient
operation.
SUMMARY OF THE INVENTION
[0006] A reciprocating pump assembly according to the present
invention includes a linear electric motor having a cylinder, a
rotor, and a stator. A multiple of check valves are located near
each end of the cylinder. Pairs of check valves are mounted within
a T-shaped fitting which permit each fitting to operate
alternatively as an inlet and a discharge depending on the
direction of the rotor stroke.
[0007] Operation of the pump assembly utilizes the rotor as a
piston within the cylinder. As the rotor is driven toward one
endplate, one check valve within each fitting is open and one is
closed to permit the opposed fittings to alternatively operate as
the inlet and the discharge. When the rotor is driven toward the
opposite endplate, the check valves reverse and the fittings
reverse operation. The reciprocating pump assembly provides
compression during each stroke of the rotor.
[0008] Another embodiment of the pump assembly utilizes the rotor
to drive separate pistons through pushrods. The check valves may be
reed valves located directly within the piston cylinders to provide
other packaging possibilities.
[0009] The present invention therefore provides a reciprocating air
compressor which generally matches the required load to provide
efficient operation.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The various features and advantages of this invention will
become apparent to those skilled in the art from the following
detailed description of the currently preferred embodiment. The
drawings that accompany the detailed description can be briefly
described as follows:
[0011] FIG. 1 is a general sectional view of a reciprocating pump
assembly according to the present invention;
[0012] FIG. 2A is a sectional view of a reciprocating pump assembly
in a first position;
[0013] FIG. 2B is a sectional view of a reciprocating pump assembly
in a second position;
[0014] FIG. 2C is a sectional view of a reciprocating pump assembly
in a third position;
[0015] FIG. 2D is a sectional view of a reciprocating pump assembly
in a fourth position; and
[0016] FIG. 3 is a sectional view of another reciprocating pump
assembly according to the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0017] FIG. 1 illustrates a schematic sectional view of a
reciprocating pump assembly 10. The pump assembly 10 generally
includes a linear electric motor 11 having a cylinder 12, a rotor
14, and a stator 16. A first check valve 18, a second check valve
20, a third check valve 22 and fourth check valve 24 are located in
pairs near each end of the cylinder 12. It should be understood
that although the pump assembly 10 is described as a compressor for
a gas, other uses such as compressor and pump uses for gases and/or
fluids will likewise benefit from the present invention.
[0018] The cylinder 12 defines a longitudinal axis A. Preferably,
the cylinder 12 is a tubular member which surrounds the rotor 14.
The cylinder 12 includes opposed endplates 26, 28 which may be
selectively opened to receive the rotor 14. It should be understood
that the cylinder need not be linear.
[0019] The rotor 14 is preferably an inductor rotor which includes
an iron core 30 with alternating bands of copper 32 and iron 34
mounted about said iron core 30. It should be understood that other
induction rotors with an inner core of ferrous material and an
outer layer of conductive material may also be used with the
present invention.
[0020] A seal 36 such as an O-ring is preferably located near each
end of the rotor 14 to center and seal the rotor within the
cylinder 12. The seal 36 essentially provides a sliding bearing
seal for the rotor 14. That is, due to the seals the rotor 14
operates as a piston within the cylinder 12.
[0021] Each endplate 26, 28 mounts a pair of check valves 18, 20
and 22, 24 within a T-shaped fitting 38, 40. The check valves are
each preferably mounted within the T-shaped fitting 38, 40 such
that the check valves 18, 20 and 22, 24 permit each fitting 38, 40
to operate alternatively such that when one check valve is open 18,
22 the opposed check valves 20, 24 are closed. The fittings 38, 40
alternate between operation as either an inlet or a discharge from
the cylinder 12. The fittings 38, 40 provide communication through
a multiple of conduits C1-C4 to transfer a fluid medium from a
source to a destination.
[0022] The stator 16 is mounted about the cylinder 12 to drive the
rotor 14 in response to a controller 44. The stator 16 includes a
multiple of cooling fins 46 interspersed between a multiple of
magnets 48. The multiple of cooling fins 46 and the multiple of
magnets 48 are axially retained with a tie-rod 49. The magnets 48
are preferably electromagnetic stator windings such as wire wound
into coils, however, other magnets may also be utilized by the
present invention. Preferably, only three windings (one for each
phase) need be used with the present invention.
[0023] The controller 44 may be a variable speed controller, a
switched reluctance speed controller or other controller which
controls a poly-phase power source 50. The controller 44 reverses
movement of the rotor 14 along the longitudinal axis A by
interchanging two of the three phases as generally known. Known
chip sets and transistor modules are available to provide an
induction variable speed drive controller 44 and need not be fully
described herein.
[0024] Referring to FIG. 2A, operation of the pump assembly 10
begins with the rotor 14 being driven toward one endplate 26 as
indicated by arrow X1. In this embodiment, the rotor 14 operates as
a piston within the cylinder 12. As the rotor 14 is driven toward
endplate 26, the check valve 18 located within the T-shaped fitting
38 is open and the check valve 20 within the T-shaped fitting 38 is
closed such that fitting 38 operates as a discharge and fitting 40
operates as an inlet. Fluid within the cylinder 12 forward of the
rotor 14 discharges through check valve 18. Simultaneously
therewith, the rotor 14 moves away from endplate 28 (FIG. 3B) such
that the check valve 24 located within the T-shaped fitting 40 is
open and the check valve 22 within the T-shaped fitting 40 is
closed such that fluid is drawn in behind the rotor 14 (relative to
Arrow X1). It should be understood that relative positional terms
such as "forward," "aft," "upper," "lower," "above," "below,"
"behind" and the like are with reference to the figures only and
should not be considered otherwise limiting.
[0025] Referring to FIG. 3C, the rotor 14 has reached the end of
stroke and is adjacent to the endplate 26. Fluid forward of the
rotor 14 has been expelled through check valve 18 and fluid is
drawn in behind the rotor 14 through check valve 24. At the end of
stroke, the controller 44 reverses direction of the rotor 14 (FIG.
3D) and the cycle begins again with the check valves operating in
reverse.
[0026] Referring to FIG. 2D, the rotor 14 is driven toward the
endplate 28 as indicated by arrow X2. As the rotor 14 is driven
toward endplate 28, the check valve 18 located within the T-shaped
fitting 38 is closed and the check valve 20 within the T-shaped
fitting 38 is open such that the fitting 38 operates as an inlet
and fitting 40 operates as a discharge. Simultaneously therewith,
the rotor 14 moves away from endplate 26 such that the check valve
24 located within the T-shaped fitting 40 is closed and the check
valve 22 within the T-shaped fitting 40 is open such that air is
drawn in behind the rotor 14 (relative to arrow X2). The T-shaped
fitting 40 now operates as discharge.
[0027] The pump assembly 10 thereby operates to compress fluid as
the rotor 14 moves in both directions improving the efficiency
thereof. The pump assembly 10 thereby cycles between fittings 38,
40 to provide intake/discharge on each stroke of the rotor 14. The
controller 44 preferably controls the cycle time of the rotor 14 to
provide a desired output.
[0028] Referring to FIG. 3, another pump assembly 52 includes a
linear electric motor 54 which drives a first and a second piston
56, 58 within a respective piston cylinder 60, 62. The pistons 56,
58 are respectively linked to a rotor 64 of the linear electric
motor 54 through pushrods 66, 68. In this embodiment the rotor 64
and pistons 56, 58 are separate which provides different packaging
possibilities. Pairs of check valves 70, 72 and 74, 76 are located
within the respective piston cylinders 60, 62. The check valves
70-76 are preferably reed valves, however other one-way valves may
also be used with this embodiment. A stator 78 is mounted about the
rotor 64 to drive the rotor 64 and connected pistons 56, 58 in
response to a controller 80. As the rotor cycles along axis A, the
check valves 70-76 operate generally as described above to provide
pumping and compression during each cycle of the rotor 64.
[0029] Although particular step sequences are shown, described, and
claimed, it should be understood that steps may be performed in any
order, separated or combined unless otherwise indicated and will
still benefit from the present invention.
[0030] The foregoing description is exemplary rather than defined
by the limitations within. Many modifications and variations of the
present invention are possible in light of the above teachings. The
preferred embodiments of this invention have been disclosed,
however, one of ordinary skill in the art would recognize that
certain modifications would come within the scope of this
invention. It is, therefore, to be understood that within the scope
of the appended claims, the invention may be practiced otherwise
than as specifically described. For that reason the following
claims should be studied to determine the true scope and content of
this invention.
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