U.S. patent application number 10/617329 was filed with the patent office on 2004-03-25 for reciprocating compressor with a linear motor.
This patent application is currently assigned to Bristol Compressors, Inc.. Invention is credited to Monk, David Turner, Narney, John Kenneth II.
Application Number | 20040055458 10/617329 |
Document ID | / |
Family ID | 31997473 |
Filed Date | 2004-03-25 |
United States Patent
Application |
20040055458 |
Kind Code |
A1 |
Monk, David Turner ; et
al. |
March 25, 2004 |
Reciprocating compressor with a linear motor
Abstract
A reciprocating compressor having a linear motor, at least one
piston and cylinder arrangement and a mechanism operatively
connecting the linear motor to the piston and cylinder arrangement
is provided. The piston and cylinder arrangement operate to
compress a fluid, preferably a refrigerant gas. The piston and
cylinder arrangement has a cylinder, a piston configured and
disposed to travel in the cylinder and a piston rod connected to
the piston. The mechanism connects the linear motor to the piston
rod to move the piston in the cylinder upon operation of the linear
motor. The mechanism is configured and disposed to limit overtravel
of the piston in the cylinder in response to a light load of the
reciprocating compressor and to limit undertravel of the piston in
the cylinder in response to a heavy load in the reciprocating
compressor. The mechanism connecting the linear motor to the piston
and cylinder arrangement can include a connecting rod and
eccentric, a cam mechanism, a wobble plate mechanism, a gear
mechanism, or a track mechanism.
Inventors: |
Monk, David Turner;
(Bristol, VA) ; Narney, John Kenneth II; (Bristol,
VA) |
Correspondence
Address: |
MCNEES WALLACE & NURICK LLC
100 PINE STREET
P.O. BOX 1166
HARRISBURG
PA
17108-5300
US
|
Assignee: |
Bristol Compressors, Inc.
Bristol
VA
|
Family ID: |
31997473 |
Appl. No.: |
10/617329 |
Filed: |
July 10, 2003 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
60394739 |
Jul 10, 2002 |
|
|
|
Current U.S.
Class: |
92/140 |
Current CPC
Class: |
F04B 35/045 20130101;
F01B 9/047 20130101; F04B 9/047 20130101; F04B 35/01 20130101; F01B
9/06 20130101 |
Class at
Publication: |
092/140 |
International
Class: |
F01B 009/00 |
Claims
1. A reciprocating compressor comprising: a linear motor; at least
one piston and cylinder arrangement, the piston and cylinder
arrangement comprising a cylinder, a piston configured and disposed
to travel in the cylinder and a piston rod connected to the piston;
and a mechanism operatively connecting the linear motor to the at
least one piston and cylinder arrangement to move the piston in the
cylinder upon operation of the linear motor, the mechanism having a
mechanical configuration to limit overtravel and undertravel of the
piston in the cylinder.
2. The compressor of claim 1 wherein the mechanism comprises a
connecting rod and eccentric.
3. The compressor of claim 1 wherein the mechanism comprises a cam
mechanism.
4. The compressor of claim 1 wherein the mechanism comprises a
wobble plate mechanism.
5. The compressor of claim 1 wherein the mechanism comprises a gear
mechanism.
6. The compressor of claim 5, wherein the gear mechanism comprises
a linear gear connected to the linear motor.
7. The compressor of claim 6, wherein the linear gear comprises at
least one gear surface, the gear mechanism comprises at least one
connecting gear to contact the at least one gear surface of the
linear gear, the at least one connecting gear being connected to a
piston rod, and the at least one gear surface being configured to
provide a pre-determined and controlled travel path for the piston
rod and piston.
8. The compressor of claim 7, wherein the gear surface is
substantially parallel with the longitudinal axis of the linear
gear.
9. The compressor of claim 8, wherein the gear surface is selected
from the group consisting of square-toothed, grooved, and
serrated.
10. The compressor of claim 1, wherein the mechanism is a track
mechanism.
11. The compressor of claim 10, wherein the track mechanism
includes a drive block having an embedded track, a drive pin at
least partially disposed in the embedded track and connected to the
linear motor and one or more piston rods, the drive pin being
configured to move in the track to move the one or more piston rods
in response to operation of the linear motor.
12. The compressor of claim 1 wherein the track has a shape and
slope to permit the drive pin to smoothly engage one or more piston
rods to drive the corresponding pistons up and down in the cylinder
and the track is configured to provide a predetermined and
controlled travel path for the one or more piston rods and
pistons.
13. The compressor of claim 12, wherein the travel path includes a
constant predetermined top-dead center piston position and
bottom-dead center piston position.
14. The compressor of claim 13, wherein the track comprises at
least one substantially horizontal non-sloped track section
corresponding to the top dead center piston position and to the
bottom dead center piston position, wherein the piston is
relatively motionless in the cylinder until the pin is pulled or
pushed back into the sloped portion of the track by the linear
motor.
15. A mechanism to connect a linear motor to a piston-cylinder
arrangement, the mechanism having a mechanical configuration to
limit overtravel and undertravel of the piston in the cylinder.
16. The mechanism of claim 15 wherein the mechanism comprises a
connecting rod and eccentric.
17. The mechanism of claim 16 wherein the mechanism comprises a cam
mechanism.
18. The mechanism of claim 17 wherein the mechanism comprises a
wobble plate mechanism.
19. The mechanism of claim 18 wherein the mechanism comprises a
gear mechanism.
20. The mechanism of claim 19, wherein the gear mechanism comprises
a linear gear connected to the linear motor.
21. The mechanism of claim 20, wherein the linear gear comprises at
least one gear surface, the gear mechanism comprises at least one
connecting gear to contact the at least one gear surface of the
linear gear, the at least one connecting gear being connected to a
piston rod, and the at least one gear surface being configured to
provide a pre-determined and controlled travel path for the piston
rod and piston.
22. The mechanism of claim 21, wherein the at least one gear
surface is substantially parallel with the longitudinal axis of the
linear gear.
23. The mechanism of claim 22, wherein the at least one gear
surface is selected from the group consisting of square-toothed,
grooved, and serrated.
24. The mechanism of claim 15, wherein the mechanism is a track
mechanism.
25. The mechanism of claim 24, wherein the track mechanism includes
a drive block having an embedded track, a drive pin at least
partially disposed in the embedded track and connected to the
linear motor and one or more piston rods, the drive pin being
configured to move in the track to move the one or more piston rods
in response to operation of the linear motor.
26. The mechanism of claim 25, wherein the track has a shape and
slope to permit the drive pin to smoothly engage one or more piston
rods to drive the corresponding pistons up and down in the cylinder
and the track is configured to provide a predetermined and
controlled travel path for the one or more piston rods and
pistons.
27. The mechanism of claim 26, wherein the travel path includes a
constant predetermined top-dead center piston position and
bottom-dead center piston position.
28. The mechanism of claim 27, wherein the track comprises at least
one substantially horizontal non-sloped track section corresponding
to the top dead center piston position and to the bottom dead
center piston position, wherein the piston is relatively motionless
in the cylinder until the pin is pulled or pushed back into the
sloped portion of the track by the linear motor.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application No. 60/394,739 filed Jul. 10, 2002, which Provisional
Application is incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] The present invention is related generally to a mechanical
linkage for connecting a linear motor to a piston or pistons of a
reciprocating compressor. Specifically, the present invention is
directed to a mechanical linkage for a linear motor that defines a
travel path for the piston(s).
[0003] A standard refrigeration or heating, ventilation and air
conditioning (HVAC) system includes a refrigerant fluid, an
evaporator, a compressor, a condenser, and an expansion valve. In a
typical refrigeration cycle, the compressor compresses a
refrigerant vapor and delivers the vapor to the condenser through a
discharge line. The refrigerant vapor delivered to the condenser
enters into a heat exchange relationship with another fluid in the
condenser and undergoes a phase change to a refrigerant liquid as a
result of the heat exchange relationship with the other condenser
fluid. The condensed liquid refrigerant from the condenser flows
through an expansion valve to the evaporator. The liquid
refrigerant in the evaporator enters into a heat exchange
relationship with another fluid in the evaporator and undergoes a
phase change to a refrigerant vapor as a result of the heat
exchange relationship with the other evaporator fluid. The vapor
refrigerant in the evaporator exits the evaporator and returns to
the compressor by a suction line to complete the cycle. By means of
example only, the refrigerant fluid used in the system can be
ammonia, ethyl chloride, CFCs, HFCs, Freon.RTM., or other known
refrigerants.
[0004] One type of compressor that can be used in a HVAC or
refrigeration system is a reciprocating compressor. A linear motor
can be used to drive the reciprocating compressor to improve the
efficiency and/or reliability of the compressor. In some
applications, linear motors are used with small compressors without
positive travel stops for the piston and drive mechanism. However,
when the linear motor is connected or attached directly to a piston
to compress refrigerant gas, the piston has a tendency to
overtravel in light load conditions and undertravel in high load
conditions.
[0005] Therefore, what is needed is a mechanism to connect between
a linear motor and a piston of reciprocating compressor that can
operate as a motion stop for a linear motor, define a positive
predetermined piston path at all load conditions and prevent
undertravel and overtravel of the piston driver assembly.
SUMMARY OF THE INVENTION
[0006] One embodiment of the present invention is directed to a
reciprocating compressor having a linear motor, at least one piston
and cylinder arrangement and a mechanism operatively connecting the
linear motor to the piston and cylinder arrangement. The piston and
cylinder arrangement operates to compress a fluid, preferably a
refrigerant gas, and has a cylinder, a piston configured and
disposed to travel in the cylinder, and a piston rod connected to
the piston. The mechanism connects the linear motor to the piston
rod to move the piston in the cylinder upon operation of the linear
motor. The mechanism is configured and disposed to limit overtravel
of the piston in the cylinder in response to a light load of the
reciprocating compressor and to limit undertravel of the piston in
the cylinder in response to a heavy load in the reciprocating
compressor. The mechanism connecting the linear motor to the piston
and cylinder arrangement can include a connecting rod and
eccentric, a cam mechanism, a wobble plate mechanism, or a track
mechanism, among other things.
[0007] Another embodiment of the present invention is directed to a
mechanism for connecting a linear motor to a piston-cylinder
arrangement such as in a reciprocating compressor. In this
embodiment, the mechanism operates to move the piston in the
cylinder upon operation of the linear motor, and includes a
mechanical configuration to limit overtravel and undertravel of the
piston in the cylinder.
[0008] One advantage of the present invention is that it prevents
undertravel and overtravel of the piston driver assembly when a
linear motor is used with a reciprocating compressor.
[0009] Another advantage of the present invention is that the
piston travels a positive and predetermined path when a linear
motor is used with a reciprocating compressor.
[0010] Other features and advantages of the present invention will
be apparent from the following more detailed description of the
preferred embodiment, taken in conjunction with the accompanying
drawings which illustrate, by way of example, the principles of the
invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 illustrates schematically a first embodiment of a
mechanical linkage configuration of the present invention.
[0012] FIG. 2 illustrates schematically a second embodiment of a
mechanical linkage configuration of the present invention.
[0013] FIG. 3 illustrates schematically a third embodiment of a
mechanical linkage configuration of the present invention.
[0014] Wherever possible, the same reference numbers will be used
throughout the drawings to refer to the same or like parts.
DETAILED DESCRIPTION OF THE INVENTION
[0015] FIGS. 1-3 illustrate several embodiments of the present
invention. A linear motor 10 is used to drive or move a mechanism
that defines the path of the piston or pistons 30 in a
reciprocating compressor 40. It is to be understood that the
reciprocating compressor 40 includes many other components that are
well known in the art which are not shown herein for purposes of
simplicity and clarity. The mechanism can be a connecting rod
eccentric type mechanism 20 as shown in FIG. 1, or the mechanism
can be any other type of piston path defining mechanism, including
but not limited to a cam type, gear type, sliding track type,
"wobble plate" type or any other suitable piston path defining
mechanism. In the embodiments of the present invention, the
mechanism controls the path and travel of one or more pistons 30,
thereby preventing each piston 30 from overextension during light
loads and underextension during heavy loads. Preferably, the
mechanism 20 provides a constant predetermined top dead center
piston position and bottom dead center piston position to limit or
eliminate overtravel and undertravel of the piston 30 in the
cylinder 50.
[0016] The reciprocating compressor 40 of the present invention
includes one or more cylinders 50. Positioned in each of the
cylinder(s) 50 is a piston 30 that can move back and forth in the
cylinder 50 in an axial direction. The piston 30 is used to
compress a refrigerant gas in the cylinder 50 by traveling toward a
closed end of the cylinder 50 to compress the refrigerant gas
between the piston face and the closed end of the cylinder. A
piston rod 32 is connected to the piston 30 to move the piston 30
in the cylinder 50. The piston rod 32 is connected to a connecting
mechanism 20 (see FIG. 1), which in turn is connected to the linear
motor 10. Preferably, the connecting mechanism 20 also operates to
limit movement of the piston rod 32 in the axial direction while
moving the piston 30 toward the closed end of the cylinder 50 and
while withdrawing the piston 30 from the closed end of the cylinder
50. The operation of the linear motor 10 and connecting mechanism
20 displace the piston rod 32 to move the piston 30 back and forth
in the cylinder 50.
[0017] During operation of the linear motor 10, one or more stators
8 drive or move a rotor 12 back and forth in the same axial
direction as the piston 30 as shown in FIG. 1. Connected to the
rotor 12 are one or more connecting linkages 14 that connect the
rotor 12 to the connecting mechanism 20. The connecting mechanism
20 shown in FIG. 1 is a connecting rod eccentric type mechanism 20
mounted on bearings 21 or other suitable rotating structures using
known methods in the art. The movement of the rotor 12 of the
linear motor 10 moves the connecting linkages 14, which turn or
displace the connecting mechanism 20 thereby moving the piston rod
32 to propel the piston 30 back and forth in the cylinder 50. The
movement of the piston 30 and piston rod 32 in the cylinder 50 is
dependent on the direction of movement of the rotor 12 and linkages
14 and the particular configuration of the connecting mechanism 20.
The use of the connecting mechanism 20 defines a positive,
controlled and predetermined travel path for the piston rod 32 and
piston 30, thereby preventing the overextension or underextension
of the piston 30 during certain loading conditions of the
compressor.
[0018] As shown in FIG. 2, a gear-type mechanism 120 is used to
connect the linear motor 10 and the piston rod(s) 32. The mechanism
120 includes a linear gear 22 that is connected to and driven by
the linkage 14 that is driven by the rotor 12. The liner gear 22
preferably includes opposed first and second gear surfaces 24, 26.
Preferably, each gear surface 24, 26 is substantially parallel with
the longitudinal axis of the linear gear 22. The gear surface 24,
26 may be any suitable gear surface type, such as square-toothed,
grooved, or serrated. As shown in FIG. 2, each gear surface 24, 26
contacts a connecting gear 28 that is connected to a corresponding
piston rod 32. Each connecting gear 28 is shaped so as to smoothly
engage the gear surface 24, 26 to drive the connecting rod 32 with
a minimum of energy loss, and to provide a pre-determined and
controlled travel path for the piston rod 32 and piston 30.
Preferably, the travel path includes predetermined top-dead center
piston position and bottom-dead center piston position which remain
constant despite load increases and decreases. In an alternative
embodiment not illustrated, a single gear surface is provided on
the linear gear, with a plurality of connecting gears aligned such
that each connecting gear is in contact with the gear surface, each
connecting gear driving a corresponding piston rod to propel a
corresponding piston.
[0019] As shown in FIG. 3, a track-type mechanism 220 is used to
connect the linear motor 10 and piston rod(s) 32. The mechanism 220
includes a drive block 60 having an embedded track 62 for receiving
a drive pin 64. The drive pin 64 is connected to the linkage 14
that is in turn driven by the rotor 12. The drive pin 64 is also
connected to one or more piston rods 32. As the rotor 12 drives the
linkage 14, the drive pin 64 is moved in the track 62. As the drive
pin 64 moves, it pushes the piston rod 32 to force the piston 30 to
move in the cylinder 50. The track 62 is shaped and sloped so as to
smoothly engage the piston connecting rod 32 to drive the piston 30
up and down in the cylinder 50 with a minimum of energy loss, and
to provide a pre-determined and controlled travel path for the
piston rod 32 and piston 30. Preferably, the travel path includes
predetermined top-dead center piston position and bottom-dead
center piston position which remain constant despite load increases
and decreases. In the embodiment of FIG. 3, these positions are
accomplished by the inclusion of substantially horizontal,
non-sloped track sections 66 at each end of the track 62. When the
drive pin 64 enters a horizontal section 66, the position of the
connecting rod 32 remains substantially vertically constant, so
that the piston 30 is neither driven up nor pulled down until the
pin is pulled or pushed back into the sloped portion of the track
by the linkage 14. Preferably, as shown in FIG. 3, more than one
piston rod 32 is connected to the drive pin 64 so that
reciprocating opposed pistons 30 can be driven as the pin 64 moves
throughout the track 62.
[0020] While the invention has been described with reference to a
preferred embodiment, it will be understood by those skilled in the
art that various changes may be made and equivalents may be
substituted for elements thereof without departing from the scope
of the invention. In addition, many modifications may be made to
adapt a particular situation or material to the teachings of the
invention without departing from the essential scope thereof.
Therefore, it is intended that the invention not be limited to the
particular embodiment disclosed as the best mode contemplated for
carrying out this invention, but that the invention will include
all embodiments falling within the scope of the appended
claims.
* * * * *