U.S. patent number RE40,257 [Application Number 10/675,907] was granted by the patent office on 2008-04-22 for compressor pulse width modulation.
This patent grant is currently assigned to Emerson Climate Technologies, Inc.. Invention is credited to Mark Bass, Roy J. Doepker, James F. Fogt, Jeffrey A. Huddleston.
United States Patent |
RE40,257 |
Doepker , et al. |
April 22, 2008 |
Compressor pulse width modulation
Abstract
A scroll compressor includes a capacity modulation system. The
capacity modulation system has a piston that is connected to the
non-orbiting scroll that disengages the non-orbiting scroll from
the orbiting scroll when a pressure chamber is placed in
communication with the suction chamber of the compressor. The
non-orbiting scroll member moves into engagement with the orbiting
scroll when the chamber is placed in communication with the
discharge chamber. The engagement between the two scrolls is broken
when the pressure chamber is placed in communication with fluid
from the suction chamber. A solenoid valve controls the
communication between the pressure chamber and the suction chamber.
By operating the valve in a pulsed width modulated mode, the
capacity of the compressor can be infinitely varied between zero
and one hundred percent.
Inventors: |
Doepker; Roy J. (Lima, OH),
Bass; Mark (Wilder, KY), Fogt; James F. (Sidney, OH),
Huddleston; Jeffrey A. (Sidney, OH) |
Assignee: |
Emerson Climate Technologies,
Inc. (Sidney, OH)
|
Family
ID: |
23587368 |
Appl.
No.: |
10/675,907 |
Filed: |
September 29, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
09401343 |
Sep 21, 1999 |
06213731 |
Apr 10, 2001 |
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Current U.S.
Class: |
417/310;
62/228.5; 417/440; 417/299 |
Current CPC
Class: |
F01C
21/108 (20130101); F04C 27/005 (20130101); F04C
18/0207 (20130101); F04C 28/265 (20130101); F04C
18/0215 (20130101); F01C 21/10 (20130101); F04C
28/26 (20130101); F04C 2270/58 (20130101); F25B
2600/2509 (20130101); F25B 2400/13 (20130101); F25B
2600/0261 (20130101) |
Current International
Class: |
F04B
49/02 (20060101); F25B 49/02 (20060101) |
Field of
Search: |
;417/44.1,212,214,220,299,310,440 ;62/228.5,228.3,196.3
;418/55.5,57 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0 423 976 |
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Apr 1991 |
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EP |
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0 423 976 |
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Apr 1991 |
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EP |
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0 747 597 |
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Dec 1996 |
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EP |
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0 747 597 |
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Dec 1996 |
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EP |
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59-117895 |
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Aug 1984 |
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JP |
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WO 99/17066 |
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Apr 1999 |
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WO |
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WO 99 17066 |
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Apr 1999 |
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WO |
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Other References
European Search Report for Application No. EP 00 30 8176; May 3,
2002; 4 Pages. cited by other.
|
Primary Examiner: Freay; Charles G.
Attorney, Agent or Firm: Harness, Dickey & Pierce,
P.L.C.
Claims
What is claimed is:
1. A scroll-type machine comprising: a first scroll member having a
first end plate and a first spiral wrap extending therefrom; a
second scroll member having a second end plate and a second spiral
wrap extending therefrom, said first and second scroll members
being positioned with said first and second spiral wraps
interleaved with each other; a drive member for causing said scroll
members to orbit relative to one another.Iadd., .Iaddend.whereby
said spiral wraps will create pockets of progressively changing
volume between a suction pressure zone and a discharge pressure
zone; said first and second scroll members being movable between a
first relationship in which sealing surfaces of said first and
second scroll members are in sealing relationship to close off said
pockets and a second relationship wherein at least one of said
sealing surfaces of said first and second scroll members are spaced
apart to define a leakage path between said pockets; and a fluid
operated piston .Iadd.disposed in said discharge pressure zone and
.Iaddend.secured to said first scroll, said piston being actuatable
to apply a force to said first scroll to move said first scroll
between said first relationship where said scroll machine operates
at substantially full capacity and said second relationship in
which said scroll machine operates at substantially zero
capacity.
2. The scroll-type machine according to claim 1, wherein said drive
member continues to operate when said first scroll member is in
said second relationship.
3. The scroll-type machine according to claim 2, wherein said
scroll-type machine includes a discharge flow path for conducting
compressed fluid from said scroll-type machine and a check valve
located within said flow path to prevent reverse flow of said
compressed fluid.
4. The scroll-type machine according to claim 1, wherein said fluid
operated piston is operated in a time pulsed manner to modulate the
capacity of said scroll-type machine.
5. The scroll-type machine according to claim 1, further comprising
a fluid pressure chamber operative to apply said force to said
fluid operated piston.
6. The scroll-type machine according to claim 5, wherein said force
acts in an axial direction.
7. The scroll-type machine according to claim 6, further comprising
a first passage for supplying a pressurized fluid from said
scroll-type machine to said pressure chamber.
8. The scroll-type machine according to claim 7, further comprising
a valve for controlling flow through said first passage, said valve
being operative to vent said pressurized fluid from said pressure
chamber to thereby enable said first and second scrolls to move
between said first and second relationships.
9. The scroll-type machine according to claim 8, wherein said valve
is a solenoid operated valve.
10. The scroll-type machine according to claim 9, wherein said
solenoid operated valve is operated in a pulse width modulated
mode.
11. The scroll-type machine according to claim 8, further
comprising a control module in communication with said valve.
12. The scroll-type machine according to claim 11, further
comprising at least one sensor in communication with said control
module, said control module being operative to control said valve
in response to a signal from said sensor.
13. The scroll-type machine according to claim 7, further
comprising a second passage for venting said pressurized fluid from
said pressure chamber.
14. The scroll-type machine according to claim 1, wherein said
scroll-type machine includes a shell, said fluid operated piston
being slidingly received within a fitting secured to said
shell.
15. The scroll-type machine according to claim 14, wherein said
piston and said fitting define a pressure chamber.
16. The scroll-type machine according to claim 15, wherein said
pressure chamber is in communication with a suction chamber defined
by said shell.
17. The scroll-type machine according to claim 16, further
comprising a valve disposed between said pressure chamber and said
suction chamber.
18. The scroll-type machine according to claim 17, wherein said
valve is a solenoid valve.
19. The scroll-type machine according to claim 18, wherein said
solenoid valve is operated in a pulse width modulated mode.
20. The scroll-type machine according to claim 17, wherein said
pressure chamber is in communication with a discharge chamber
defined by said shell.
21. The scroll-type machine according to claim 16, wherein said
solenoid valve is operated in a pulse width modulated mode.
22. The scroll-type machine according to claim 21, further
comprising a valve disposed between said pressure chamber and both
said suction chamber and said discharge chamber.
23. The scroll-type machine according to claim 22, further
comprising a valve disposed between said pressure chamber and said
suction chamber.
24. The scroll-type machine according to claim 23, wherein said
valve is a solenoid valve.
25. A scroll-type machine comprising: a first scroll member having
a first end plate and a first spiral wrap extending therefrom; a
second scroll member having a second end plate and a second spiral
wrap extending therefrom, said first and second scroll members
being positioned with said first and second spiral wraps
interleaved with each other; .Iadd.a shell housing said first and
second scroll members;.Iaddend. a drive member for causing said
scroll members to orbit relative to one another whereby said spiral
wraps will create pockets of progressively changing volume between
a suction pressure zone and a discharge pressure zone; said first
and second scroll members being movable between a first
relationship in which sealing surfaces of said first and second
scroll members are in sealing relationship to close off said
pockets and a second relationship wherein at least one of said
sealing surfaces of said first and second scroll members are spaced
apart to define a leakage path between said pockets; a fluid
operated piston secured to said first scroll and slidingly received
within a bore defined by said shell, said piston being actuatable
to apply a force to said first scroll to move said first scroll
between said first relationship where said scroll machine operates
at substantially full capacity and said second relationship in
which said scroll machine operates at substantially zero capacity;
and a radially compliant sealing system disposed between said
piston and said bore defined by said shell.
26. The scroll-type machine according to claim 25, further
comprising an annular fitting disposed between said shell and said
piston, said radially complaint sealing system being disposed
between said piston and said fitting.
27. The scroll-type machine according to claim 25, wherein said
radially complaint sealing system includes a lip seal.
28. The scroll-type machine according to claim 27, wherein said
radially complaint sealing system includes a floating retainer.
29. The scroll-type machine according to claim 25, wherein said
radially complaint sealing system includes a floating retainer.
30. A scroll-type machine comprising: a first scroll member having
a first end plate and a first spiral wrap extending from said first
end plate; a second scroll member having a second end plate and a
second spiral wrap extending from said second end plate, said first
and second scroll members being positioned with said first and
second spiral wraps interleaved with each other; a drive member for
causing said scroll members to orbit relative to one another
whereby said spiral wraps will create pockets of progressively
changing volume between a suction pressure zone and a discharge
pressure zone; a mechanism for moving said first and second scroll
members between a first relationship where sealing surfaces of said
first and second scroll members are in sealing relationship to
close off said pockets and a second relationship where at least one
of said sealing surfaces of said first and second scroll members
are spaced apart to define a leak path between said pockets; and a
fluid injection system associated with one of said scroll members
for injecting a fluid into at least one of said pockets.
31. The scroll-type machine according to claim 30, wherein said
mechanism is operated in a pulse width modulation mode.
32. The scroll-type machine according to claim 31, wherein said
fluid being injected into said at least one of said pockets is a
vapor.
33. The scroll-type machine according to claim 30, wherein said
mechanism includes a solenoid valve.
34. The scroll-type machine according to claim 33, wherein said
solenoid valve is operated in a pulse width modulation mode.
35. The scroll-type machine according to claim 30, wherein said
mechanism includes a fluid operated piston secured to said first
scroll, said piston being activatable to apply a force to said
first scroll to move said first scroll between said first and
second relationships.
36. The scroll-type machine according to claim 35, wherein said
drive member continues to operate when said first scroll member is
in said second relationship.
37. The scroll-type machine according to claim 35, wherein said
fluid operated piston is operated in a time pulsed manner to
modulate the capacity of said scroll-type machine.
38. The scroll-type machine according to claim 37, wherein said
fluid injection system includes a solenoid valve for controlling
flow of said fluid to said one of said scroll members.
39. The scroll-type machine according to claim 38, wherein said
solenoid valve is operated in a pulse width modulation mode.
40. The scroll-type machine according to claim 39, wherein said
fluid being injected into one of said pockets is a vapor.
41. The scroll-type machine according to claim 35, wherein said
fluid being injected into said at least one of said pockets is a
vapor.
42. The scroll-type machine according to claim 30, wherein said
fluid injection system includes a solenoid valve for controlling
flow of said fluid to said one of said scroll members.
43. The scroll-type machine according to claim 42, wherein said
solenoid valve is operated in a pulse width modulation mode.
44. The scroll-type machine according to claim 43, wherein said
fluid being injected into one of said pockets is a vapor.
45. A scroll-type machine comprising: a first scroll member having
a first end plate and a first spiral wrap extending from said first
end plate; a second scroll member having a second end plate and a
second spiral wrap extending from said second end plate, said first
and second scroll members being positioned with said first and
second spiral wraps interleaved with each other; a drive member for
causing said scroll members to orbit relative to one another
whereby said spiral wraps will create pockets of progressively
changing volume between a suction pressure zone and a discharge
pressure zone; and a vapor injection system associated with one of
said scroll members for injecting a vapor into at least one of said
pockets, said vapor injection system including a valve for
controlling said vapor being injected into said at least one of
said pockets.
46. The scroll-type machine according to claim 45, wherein said
valve is a solenoid valve.
47. The scroll-type machine according to claim 46, wherein said
solenoid valve is operated in a pulse width modulation mode.
48. The scroll-type machine according to claim 47, wherein said
fluid being injected into one of said pockets is a vapor.
.Iadd.49. The scroll-type machine according to claim 1, wherein
said fluid operated piston is responsive to a discharge pressure in
said discharge pressure zone..Iaddend.
.Iadd.50. A scroll-type machine comprising: a first scroll member
having a first end plate and a first spiral wrap extending
therefrom; a second scroll member having a second end plate and a
second spiral wrap extending therefrom, said first and second
scroll members being positioned with said first and second spiral
wraps interleaved with each other; a shell housing said first and
second scroll members; a drive member for causing said first and
second scroll members to orbit relative to one another, whereby
said spiral wraps will create pockets of progressively changing
volume between a suction pressure zone and a discharge pressure
zone; said first and second scroll members being movable between a
first relationship in which sealing surfaces of said first and
second scroll members are in sealing relationship to close off said
pockets and a second relationship wherein at least one of said
sealing surfaces of said first and second scroll members are spaced
apart to define a leakage path between said pockets; a fluid
operated piston secured to said first scroll member, said piston
being actuatable to apply a force to said first scroll member to
move said first scroll member between said first relationship where
said scroll machine operates at substantially full capacity and
said second relationship in which said scroll machine operates at
substantially zero capacity; and a sealing system operable to
provide radial compliance between said first scroll member and said
shell..Iaddend.
.Iadd.51. The scroll-type machine according to claim 50, further
comprising an annular fitting disposed between said shell and said
piston, said sealing system being disposed between said piston and
said fitting..Iaddend.
.Iadd.52. The scroll-type machine according to claim 51, wherein
said sealing system includes a seal and a floating
retainer..Iaddend.
.Iadd.53. The scroll-type machine according to claim 50, wherein
said sealing system includes a lip seal..Iaddend.
.Iadd.54. The scroll-type machine according to claim 53, wherein
said sealing system includes a floating retainer..Iaddend.
.Iadd.55. The scroll-type machine according to claim 50, wherein
said sealing system includes a floating retainer..Iaddend.
Description
FIELD OF THE INVENTION
The present invention is related to scroll-type machinery. More
particularly, the present invention is directed towards capacity
modulation of scroll-type compressors.
BACKGROUND AND SUMMARY OF THE INVENTION
Scroll machines are becoming more and more popular for use as
compressors in refrigeration systems as well as air conditioning
and heat pump applications. The popularity of scroll machinery is
primarily due to their capability for extremely efficient
operation. Generally, these machines incorporate a pair of
intermeshed spiral wraps, one of which is caused to orbit with
respect to the other so as to define one or more moving chambers
which progressively decrease in size as they travel from an outer
suction port towards a center discharge port. An electric motor is
normally provided which operates to drive the scroll members via a
suitable drive shaft. During normal operation, these scroll
machines are designed to have a fixed compression ratio.
Air conditioning and refrigeration systems experience a wide range
of loading requirements. Using a fixed compression ratio compressor
to meet this wide range of loading requirements can present various
problems to the designer of the system. One method of adapting the
fixed compression ratio compressors to the wide range of loading
requirements is to incorporate a capacity modulation system into
the compressor. Capacity modulation has proven to be a desirable
feature to incorporate into the air conditioning and refrigeration
compressors in order to better accommodate the wide range of
loading to which the systems may be subjected. Many different
approaches have been utilized for providing this capacity
modulation feature. These prior art systems have ranged from
control of the suction inlet to bypassing compressed discharge gas
directly back into the suction area of the compressor. With
scroll-type compressors, capacity modulation has often been
accomplished via a delayed suction approach which comprises
providing ports at various positions along the route of the
compression chambers which, when opened, allow the compression
chambers formed between the intermeshing scroll wraps to
communicate with the suction gas supply, thus delaying the point at
which compression of the suction gas begins. This delayed suction
method of capacity modulation actually reduces the compression
ratio of the compressor. While such systems are effective at
reducing the capacity of the compressor, they are only capable of
providing a predetermined or stepped amount of compressor
unloading. The amount of unloading or the size of the step is
dependent upon the positioning of the unloading ports along the
wraps or the compression process. While it is possible to provide
multiple stepped unloading by incorporating a plurality of
unloading ports at different locations along the compression
process, this approach becomes more and more costly as the number
of ports is increased and it requires additional space to
accommodate the separate controls for opening and closing each
individual on each set of ports.
The present invention, however, overcomes these deficiencies by
enabling an infinitely variable capacity modulation system which
has the capability of modulating the capacity from 100% of full
capacity down to virtually zero capacity utilizing only a single
set of controls. Further, the system of the present invention
enables the operating efficiency of the compressor and/or
refrigeration system to be maximized for any degree of compressor
unloading desired.
In the present invention, compressor unloading is accomplished by
cyclically effecting axial separation of the two scroll members
during the operating cycle of the compressor. More specifically,
the present invention provides an arrangement wherein one scroll
member is moved axially with respect to the other scroll member by
a solenoid valve which operates in a pulsed width modulation mode.
The pulsed width modulation operating mode for the solenoid valve
provides a leakage path across the tips of the wraps from the
higher compression pockets defined by the intermeshing scroll wraps
to the lower compression pockets and ultimately back to suction. By
controlling the pulse width modulation frequency and thus the
relative time between sealing and unsealing of the scroll wrap
tips, infinite degrees of compressor unloading can be achieved with
a single control system. Further, by sensing various conditions
within the refrigeration system, the duration of compressor loading
and unloading for each cycle can be selected for a given capacity
such that overall system efficiency is maximized.
The various embodiments of the present invention detailed below
provide a wide variety of arrangements by which one scroll member
may be axially reciprocated with respect to the other to
accommodate a full range of compressor unloading. The ability to
provide a full range of capacity modulation with a single control
system as well as the ability to select the duration of loaded and
unloaded operation cooperate to provide an extremely efficient
system at a relatively low cost.
Other advantages and objects of the present invention will become
apparent to those skilled in the art from the subsequent detailed
description, appended claims and drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings which illustrate the best mode presently
contemplated for carrying out the present invention:
FIG. 1 is a section view of a scroll-type refrigeration compressor
in accordance with the present invention operating at full
capacity;
FIG. 2 is a section view of the scroll-type refrigeration
compressor shown in FIG. 1 operating at a reduced capacity;
FIG. 3 is a detailed view of the ring and biasing arrangement taken
in the direction of arrows 3--3 shown in FIG. 2;
FIG. 4 is a section view of a scroll-type refrigeration compressor
in accordance with another embodiment of the present invention
operating at full capacity;
FIG. 5 is a section view of a scroll-type refrigeration compressor
in accordance with another embodiment of the present invention;
FIG. 6 is a top section view of the compressor shown in FIG. 5;
FIG. 7 is an enlarged section view of the piston assembly shown in
FIG. 5;
FIG. 8 is a top view of the discharge fitting shown in FIG. 7;
FIG. 9 is an elevational view of the biasing spring shown in FIG.
5;
FIG. 10 is a side view of the non-orbiting scroll member shown in
FIG. 5;
FIG. 11 is a cross sectional top view of the non-orbiting scroll
member shown in FIG. 10;
FIG. 12 is an enlarged sectional view of the injection fitting
shown in FIG. 5;
FIG. 13 is an end view of the fitting showing in FIG. 12;
FIG. 14 is a schematic diagram of a refrigerant system utilizing
the capacity control system in accordance with the present
invention;
FIG. 15 is a schematic diagram of a refrigerant system in
accordance with another embodiment of the present invention;
and
FIG. 16 is a graph showing the capacity of the compressor using the
capacity control system in accordance with the present
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to the drawings in which like reference numerals
designate like or corresponding parts throughout the several views,
there is shown in FIG. 1 a scroll compressor which includes the
unique capacity control system in accordance with the present
invention and which is designated generally by the reference
numeral 10. Scroll compressor 10 is generally of the type described
in Assignee's U.S. Pat. No. 5,102,316, the disclosure of which is
incorporated herein by reference. Scroll compressor 10 comprises an
outer shell 12 within which is disposed a driving motor including a
stator 14 and a rotor 16, a crankshaft 18 to which rotor 16 is
secured, an upper bearing housing 20 and a lower bearing housing
(not shown) for rotatably supporting crankshaft 18 and a compressor
assembly 24.
Compressor assembly 24 includes an orbiting scroll member 26
supported on upper bearing housing 20 and drivingly connected to
crankshaft 18 via a crankpin 28 and a drive bushing 30. A
non-orbiting scroll member 32 is positioned in meshing engagement
with orbiting scroll member 26 and is axially movably secured to
upper bearing housing 20 by means of a plurality of bolts 34 and
associated sleeve members 36. An Oldham coupling 38 is provided
which cooperates with scroll members 26 and 32 to prevent relative
rotation therebetween. A partition plate 40 is provided adjacent
the upper end of shell 12 and serves to divide the interior of
shell 12 into a discharge chamber 42 at the upper end thereof and a
suction chamber 44 at the lower end thereof.
In operation, as orbiting scroll member 26 orbits with respect to
non-orbiting scroll member 32, suction gas is drawn into suction
chamber 44 of shell 12 via a suction fitting 46. From suction
chamber 44, suction gas is sucked into compressor 24 through an
inlet 48 provided in non-orbiting scroll member 32. The
intermeshing scroll wraps provided on scroll members 26 and 32
define moving pockets of gas which progressively decrease in size
as they move radially inwardly as a result of the orbiting motion
of scroll member 26 thus compressing the suction gas entering via
inlet 48. The compressed gas is then discharged into discharge
chamber 42 through a hub 50 provided in scroll member 32 and a
passage 52 formed in partition 40. A pressure responsive discharge
valve 54 is preferably provided seated within hub 50.
Non-orbiting scroll member 32 is also provided with an annular
recess 56 formed in the upper surface thereof. A floating seal 58
is disposed within recess 56 and is biased by intermediate
pressurized gas against partition 40 to seal suction chamber 44
from discharge chamber 42. A passage 60 extends through
non-orbiting scroll member 32 to supply the intermediate
pressurized gas to recess 56.
A capacity control system 66 is shown in association with
compressor 10. Control system 66 includes a discharge fitting 68, a
piston 70, a shell fitting 72, a three-way solenoid valve 74, a
control module 76 and a sensor array 78 having one or more
appropriate sensors. Discharge fitting 68 is threadingly received
or otherwise secured within hub 50. Discharge fitting 68 defines an
internal cavity 80 and a plurality of discharge passages 82.
Discharge valve 54 is disposed within cavity 80. Thus, pressurized
gas overcomes the biasing load of discharge valve 54 to open
discharge valve 54 and allowing the pressurized gas to flow into
cavity 80, through passages 82 and into discharge chamber 42.
Referring now to FIGS. 1 and 3, discharge fitting 68 is assembled
to piston 70 by first aligning a plurality of tabs 84 on discharge
fitting 68 with a matching plurality of slots 86 formed in piston
70. Discharge fitting 68 is then rotated to the position shown in
FIG. 3 to misalign tabs 84 with slots 86. An alignment pin 88
maintains the misalignment between tabs 84 and slots 86 while a
coil spring 90 biases the two components together.
Shell fitting 72 is sealingly secured to shell 12 and slidingly
receives piston 70. Piston 70 and shell fitting 72 define a
pressure chamber 92. Pressure chamber 92 is fluidically connected
to solenoid 74 by a tube 94. Solenoid valve 74 is also in fluid
communication with discharge chamber 42 through a tube 96 and it is
in fluid communication with suction fitting 46 and thus suction
chamber 44 through a tube 98. A seal 100 is located between piston
70 and shell fitting 72. The combination of piston 70, seal 100 and
shell fitting 72 provides a self-centering sealing system to
provide accurate alignment between piston 70 and shell fitting
72.
In order to bias non-orbiting scroll member 32 into sealing
engagement with orbiting scroll member 26 for normal full load
operation as shown in FIG. 1, solenoid valve 74 is deactivated (or
it is actuated) by control module 76 to the position shown in FIG.
1. In this position, discharge chamber 42 is in direct
communication with chamber 92 through tube 96, solenoid valve 74
and tube 94. The pressurized fluid at discharge pressure within
chambers 42 and 92 will act against opposite sides of piston 70
thus allowing for the normal biasing of non-orbiting scroll member
32 towards orbiting scroll member 26 as shown in FIG. 1 to
sealingly engage the axial ends of each scroll member with the
respective end plate of the opposite scroll member. The axial
sealing of the two scroll members 26 and 32 causes compressor 24 to
operate at 100% capacity.
In order to unload compressor 24, solenoid valve 74 will be
actuated (or it is deactuated) by control module 76 to the position
shown in FIG. 2. In this position, suction chamber 44 is in direct
communication with chamber 92 through suction fitting 46, tube 98,
solenoid valve 74 and tube 94. With the discharge pressure
pressurized fluid released to suction from chamber 92, the pressure
differences on opposite sides of piston 70 will move non-orbiting
scroll member 32 upward as shown in FIG. 2 to separate the axial
ends of the tips of each scroll member with its respective end
plate to create a gap 102 which allows the higher pressurized
pockets to bleed to the lower pressurized pockets and eventually to
suction chamber 44. A wave spring 104 which is illustrated in FIG.
9 maintains the sealing relationship between floating seal 58 and
partition 40 during the modulation of non-orbiting scroll member
32. The creation of gap 102 will substantially eliminate continued
compression of the suction gas. When this unloading occurs,
discharge valve 54 will move to its closed position thereby
preventing the backflow of high pressurized fluid from discharge
chamber 42 or the downstream refrigeration system. When compression
of the suction gas is to be resumed, solenoid valve 74 will be
deactuated (or it will be actuated) to the position shown in FIG. 1
in which fluid communication between chamber 92 and discharge
chamber 42 is again created. This again allows fluid at discharge
pressure to react against piston 70 to axially engage scroll
members 26 and 32. The axial sealing engagement recreates the
compressing action of compressor 24.
Control module 76 is in communication with sensor array 78 to
provide the required information for control module 76 to determine
the degree of unloading required for the particular conditions of
the refrigeration system including scroll compressor 10 existing at
that time. Based upon this information, control module 76 will
operate solenoid valve 74 in a pulsed width modulation mode to
alternately place chamber 92 in communication with discharge
chamber 42 and suction chamber 44. The frequency with which
solenoid 74 is operated in the pulsed width modulation mode will
determine the percent capacity of operation of compressor 24. As
the sensed conditions change, control module 76 will vary the
frequency of operation for solenoid valve 74 and thus the relative
time periods at which compressor 24 is operated in a loaded and
unloaded condition. The varying of the frequency of operation of
solenoid valve 74 can cause the operation of compressor between
fully loaded or 100% capacity and completely unloaded or 0%
capacity or at any of an infinite number of settings in between in
response to system demands.
Referring now to FIG. 4, there is shown a unique capacity control
system in accordance with another embodiment of the present
invention which is designated generally as reference numeral 166.
Capacity control system 166 is also shown in association with
compressor 10. Capacity control system 166 is similar to capacity
control system 66 but it uses a two-way solenoid valve 174 instead
of three-way solenoid valve 74. Control system 166 includes
discharge fitting 68, a piston 170, shell fitting 72, solenoid
valve 174, control module 76 and sensor array 78.
Piston 170 is identical to piston 70 with the exception that piston
170 defines a passageway 106 and an orifice 108 which extend
between pressure chamber 92 and discharge chamber 42. The
incorporation of passageway 106 and orifice 108 allows the use of
two-way solenoid 174 instead of three-way solenoid 74 and the
elimination of tube 96. By eliminating tube 96, the fitting and
hole through shell 12 is also eliminated. Seal 100 is located
between piston 170 and seal fitting 72 to provide for the
self-aligning sealing system for piston 170 and fitting 72.
Solenoid 174 operates in a manner similar to solenoid 74. Pressure
chamber 92 is fluidically connected to solenoid 174 by tube 94.
Solenoid valve 174 is also in fluid communication with suction
fitting 46 and thus suction chamber 44 by tube 98.
In order to bias non-orbiting scroll member 32 into sealing
engagement with orbiting scroll member 26 for normal full load
operation, solenoid valve 174 is deactivated (or it is activated)
by control module 76 to block fluid flow between tube 94 and tube
98. In this position, chamber 92 is in communication with discharge
chamber 42 through passageway 106 and orifice 108. The pressurized
fluid at discharge pressure within chambers 42 and 92 will act
against opposite sides of piston 170 thus allowing for the normal
biasing of non-orbiting scroll member 32 towards orbiting scroll
member 26 to sealingly engage the axial ends of each scroll member
with the respective end plate of the opposite scroll member. The
axial sealing of the two scroll members 26 and 32 causes compressor
24 to operate at 100% capacity.
In order to unload compressor 24, solenoid valve 174 will be
actuated (or it will be deactuated) by control module 76 to the
position shown in FIG. 4. In this position, suction chamber 44 is
in direct communication with chamber 92 through suction fitting 46,
tube 98, solenoid valve 174 and tube 94. With the discharge
pressure pressurized fluid released to suction from chamber 92, the
pressure differences on opposite sides of piston 170 will move
non-orbiting scroll member 32 upward to separate the axial end of
the tips of each scroll member with its respective end plate and
the higher pressurized pockets will bleed to the lower pressurized
pockets and eventually to suction chamber 44. Orifice 108 is
incorporated to control the flow of discharge gas between discharge
chamber 42 and chamber 92. Thus, when chamber 92 is connected to
the suction side of the compressor, the pressure difference on
opposite sides of piston 170 will be created. Wave spring 104 is
also incorporated in this embodiment to maintain the sealing
relationship between floating seal 58 and partition 40 during
modulation of non-orbiting scroll member 32. When gap 102 is
created the continued compression of the suction gas will be
eliminated. When this unloading occurs, discharge valve 54 will
move to its closed position thereby preventing the backflow of high
pressurized fluid from discharge chamber 42 on the downstream
refrigeration system. When compression of the suction gas is to be
resumed, solenoid valve 174 will be deactuated (or it will be
actuated) to again block fluid flow between tubes 94 and 98
allowing chamber 92 to be pressurized by discharge chamber 42
through passageway 106 and orifice 108. Similar to the embodiment
shown in FIGS. 1-3, control module 76 is in communication with
sensor array 78 to provide the required information for control
module 76 to determine the degree of unloading required and thus
the frequency with which solenoid valve 174 is operated in the
pulsed width modulation mode.
Referring now to FIG. 5, there is shown a scroll compressor which
includes a unique capacity control system in accordance with
another embodiment of the present invention and which is designated
generally by the reference numeral 210.
Scroll compressor 210 comprises an outer shell 212 within which is
disposed a driving motor including a stator 214 and a rotor 216, a
crankshaft 218 to which rotor 216 is secured, an upper bearing
housing 220 and a lower bearing housing 222 for rotatably
supporting crankshaft 218 and a compressor assembly 224.
Compressor assembly 224 includes an orbiting scroll member 226
supported on upper bearing housing 220 and drivingly connected to
crankshaft 218 via a crankpin 228 and a drive bushing 230. A
non-orbiting scroll member 232 is positioned in meshing engagement
with orbiting scroll member 226 and is axially movably secured to
upper bearing housing 220 by means of a plurality of bolts (not
shown) and associated sleeve members (not shown). An Oldham
coupling 238 is provided which cooperates with scroll members 226
and 232 to prevent relative rotation therebetween. A partition
plate 240 is provided adjacent the upper end of shell 212 and
serves to divide the interior of shell 212 into a discharge chamber
242 at the upper end thereof and a suction chamber 244 at the lower
end thereof.
In operation, as orbiting scroll member 226 orbits with respect to
scroll member 232, suction gas is drawn into suction chamber 244 of
shell 212 via a suction fitting 246. From suction chamber 244,
suction gas is sucked into compressor 224 through an inlet 248
provided in non-orbiting scroll member 232. The intermeshing scroll
wraps provided on scroll members 226 and 232 define moving pockets
of gas which progressively decrease in size as they move radially
inwardly as a result of the orbiting motion of scroll member 226
thus compressing the suction gas entering via inlet 248. The
compressed gas is then discharged into discharge chamber 242 via a
discharge port 250 provided in scroll member 236 and a passage 252
formed in partition 240. A pressure responsive discharge valve 254
is preferably provided seated within discharge port 250.
Non-orbiting scroll member 232 is also provided with an annular
recess 256 formed in the upper surface thereof. A floating seal 258
is disposed within recess 256 and is biased by intermediate
pressurized gas against partition 240 to seal suction chamber 244
from discharge chamber 242. A passage 260 extends through
non-orbiting scroll member 232 to supply the intermediate
pressurized gas to recess 256.
A capacity control system 226 is shown in association with
compressor 210. Control system 266 includes a discharge fitting
268, a piston 270, a shell fitting 272, solenoid valve 174, control
module 76 and sensor array 78 having one or more appropriate
sensors. Discharge fitting 268 is threadingly received or otherwise
secured within discharge port 250. Discharge fitting 268 defines an
internal cavity 280 and a plurality of discharge passages 282.
Discharge valve 254 is disposed below fitting 268 and below cavity
280. Thus, pressurized gas overcomes the biasing load of discharge
valve 254 to open discharge valve 254 and allowing the pressurized
gas to flow into cavity 280, through passages 282 and into
discharge chamber 242.
Referring now to FIGS. 5, 7 and 8, the assembly of discharge
fitting 268 and piston 270 is shown in greater detail. Discharge
fitting 268 defines an annular flange 284. Seated against flange
284 is a lip seal 286 and a floating retainer 288. Piston 270 is
press fit or otherwise secured to discharge fitting 268 and piston
270 defines an annular flange 290 which sandwiches seal 286 and
retainer 288 between flange 290 and flange 284. Discharge fitting
268 defines passageway 106 and orifice 108 which extends through
discharge fitting 268 to fluidically connect discharge chamber 242
with a pressure chamber 292 defined by discharge fitting 268,
piston 270, seal 286, retainer 288 and shell 212. Shell fitting 272
is secured within a bore defined by shell 212 and slidingly
receives the assembly of discharge fitting 268, piston 270, seal
286 and retainer 288. Pressure chamber 292 is fluidically connected
to solenoid 174 by tube 94 and with suction fitting 246 and thus
suction chamber 244 through tube 98 in a manner similar to that
described above for control system 166. The combination of piston
270, seal 286 and floating retainer 288 provides a self-centering
sealing system to provide accurate alignment with the internal bore
of shell fitting 272. Seal 286 and floating retainer 288 include
sufficient radial compliance such that any misalignment between the
internal bore of fitting 272 and the internal bore of discharge
port 250 within which discharge fitting 268 is secured is
accommodated by seal 286 and floating retainer 288.
In order to bias non-orbiting scroll member 232 into sealing
engagement with orbiting scroll member 226 for normal full load
operation, solenoid valve 174 is deactivated (or it is activated)
by control module 76 to block fluid flow between tube 94 and tube
98. In this position, chamber 292 is in communication with
discharge chamber 242 through passageway 106 and orifice 108. The
pressurized fluid at discharge pressure within chambers 242 and 292
will act against opposite sides of piston 270 thus allowing for the
normal biasing of non-orbiting scroll member 232 towards orbiting
scroll member 226 to sealingly engage the axial ends of each scroll
member with the respective end plate of the opposite scroll member.
The axial sealing of the two scroll members 226 and 232 causes
compressor 224 to operate at 100% capacity.
In order to unload compressor 224, solenoid valve 174 will be
actuated (or it will be deactuated) by control module 76 to the
position shown in FIG. 4. In this position, suction chamber 244 is
in direct communication with chamber 292 through suction fitting
246, tube 98, solenoid valve 174 and tube 94. With the discharge
pressure pressurized fluid released to suction from chamber 292,
the pressure difference on opposite sides of piston 270 will move
non-orbiting scroll member 232 upward to separate the axial end of
the tips of each scroll member with its respective end plate and
the higher pressurized pockets will bleed to the lower pressurized
pockets and eventually to suction chamber 244. Orifice 108 is
incorporated to control the flow of discharge gas between discharge
chamber 242 and chamber 292. Thus, when chamber 292 is connected to
the suction side of the compressor, the pressure difference on
opposite sides of piston 270 will be created. Wave spring 104 is
also incorporated in this embodiment to maintain the sealing
relationship between floating seal 258 and partition 240 during
modulation of non-orbiting scroll member 232. When gap 102 is
created the continued compression of the suction gas will be
eliminated. When this unloading occurs, discharge valve 254 will
move to its closed position thereby preventing the backflow of high
pressurized fluid from discharge chamber 242 on the downstream
refrigeration system. When compression of the suction gas is to be
resumed, solenoid valve 174 will be deactuated (or it will be
actuated) to again block fluid flow between tubes 94 and 98
allowing chamber 292 to be pressurized by discharge chamber 242
through passageway 106 and orifice 108. Similar to the embodiment
shown in FIGS. 1-3, control module 76 is in communication with
sensor array 78 to provide the required information for control
module 76 to determine the degree of unloading required and thus
the frequency with which solenoid valve 174 is operated in the
pulsed width modulation mode.
Referring now to FIGS. 6, 10 and 11, the fluid injection system for
compressor 210 is shown in greater detail. Compressor 210 includes
the capability of having fluid injected into the intermediate
pressurized moving chambers at a point intermediate suction chamber
244 and discharge chamber 242. A fluid injection fitting 310
extends through shell 212 and is fluidically connected to an
injection tube 312 which is in turn fluidically connected to an
injection fitting 314 secured to non-orbiting scroll member 232.
Non-orbiting scroll member 232 defines a pair of radial passages
316 each of which extend between injection fitting 314 and a pair
of axial passages 318. Axial passages 318 are open to the moving
chambers on opposite sides of non-orbiting scroll member 232 of
compressor 224 to inject the fluid into these moving chambers as
required by a control system as is well known in the art.
Referring now to FIGS. 12 and 13, fitting 310 is shown in greater
detail. Fitting 310 comprises an internal portion 320, and an
external portion 322. Internal portion 320 includes an L-shaped
passage 324 which sealingly receives injection tube 312 at one end.
External portion 322 extends from the outside of shell 212 to the
inside of shell 212 where it is unitary or integral with internal
portion 320. A welding or brazing attachment 326 secures and seals
fitting 310 to shell 212. External portion 322 defines a bore 330
which is an extension of L-shaped passage 324. External portion 322
also defines a cylindrical bore 332 to which the tubing of the
refrigeration system is secured.
FIG. 14 illustrates a vapor injection system which provides the
fluid for the fluid injection system of compressor 210. Compressor
210 is shown in a refrigeration system which includes a condenser
350, a first expansion valve or throttle 352, a flash tank or an
economizer 354, a second expansion valve or throttle 356, an
evaporator 358 and a series of piping 360 interconnecting the
components as shown in FIG. 14. Compressor 210 is operated by the
motor to compress the refrigerant gas. The compressed gas is then
liquified by condenser 350. The liquified refrigerant passes
through expansion valve 352 and expands in flash tank 354 where it
is separated into gas and liquid. The gaseous refrigerant further
passes through piping 362 to be introduced into compressor 210
through fitting 310. On the other hand, the remaining liquid
refrigerant further expands in expansion valve 356, is then
vaporized in evaporator 358 and is again taken into compressor
210.
The incorporation of flash tank 354 and the remainder of the vapor
injection system, allows the capacity of the compressor to increase
above the fixed capacity of compressor 210. Typically, at standard
air conditioning conditions, the capacity of the compressor can be
increased by approximately 20% to provide a compressor with 120% of
its capacity as shown in the graph in FIG. 16. In order to be able
to control the capacity of compressor 210, a solenoid valve 364 is
positioned within piping 362. The amount of percent increase in the
capacity of compressor 210 can be controlled by operating solenoid
valve 364 in a pulse width modulation mode. Solenoid valve 364 when
operated in a pulse width modulation mode in combination with
capacity control system 266 of compressor 210 allows the capacity
of compressor 210 to be positioned anywhere along the line shown in
FIG. 16.
FIG. 15 illustrates a refrigerant system schematic in accordance
with another embodiment of the present invention. The refrigerant
system shown in FIG. 15 is the same as the refrigerant system shown
in FIG. 14 except that flash tank 354 has been replaced by a heat
exchanger 354'. Compressor 210 is operated by the motor to compress
the refrigerant gas. The compressed gas is then liquified by
condenser 350. The liquified refrigerant is then routed to the
liquid side of heat exchanger 354' while a second portion of the
liquified refrigerant passes through expansion valve 352 and then
is routed to the vapor side of heat exchanger 354' in a gas and
liquid state. The portion of refrigerant passing through expansion
valve 352 is heated by the portion of refrigerant passing directly
through heat exchanger to provide the vapor for injecting into
compressor 210. This gaseous refrigerant then passes through piping
362 to be introduced into compressor 210 through fitting 310. On
the other hand, the liquid refrigerant passing directly through
heat exchanger 354' expands in expansion valve 356 and is then
vaporized in evaporator 358 to again be taken into the suction side
of compressor 210. Similar to the system shown in FIG. 14, solenoid
valve 364 is positioned within piping 362 to allow the capacity of
compressor 210 to be positioned anywhere along the line shown in
FIG. 16 when used in combination with capacity control system
266.
While the above detailed description describes the preferred
embodiment of the present invention, it should be understood that
the present invention is susceptible to modification, variation and
alteration without deviating from the scope and fair meaning of the
subjoined claims.
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