U.S. patent application number 13/384811 was filed with the patent office on 2012-08-02 for suction cutoff unloader valve for compressor capacity control.
This patent application is currently assigned to CARRIER CORPORATION. Invention is credited to Alexander Lifson, Michael F. Taras.
Application Number | 20120192583 13/384811 |
Document ID | / |
Family ID | 43499599 |
Filed Date | 2012-08-02 |
United States Patent
Application |
20120192583 |
Kind Code |
A1 |
Lifson; Alexander ; et
al. |
August 2, 2012 |
Suction Cutoff Unloader Valve For Compressor Capacity Control
Abstract
A reciprocating compressor includes a first cylinder and a
second cylinder, first and second suction cutoff unloader valve
assemblies, and a controller. The first and second suction cutoff
unloader valve assemblies are integral to the compressor and are
capable of a rapid cycling to interrupt flow of refrigerant to the
first and second cylinders. The controller operates at least one of
the first suction cutoff unloader valve assembly or second suction
cut-off unloader valve assembly in the rapid cycling and monitor a
number of rapid cycles. In another aspect, a multi-stage compressor
comprises a lower pressure stage and a higher pressure stage, and
at least one suction cutoff unloader valve assembly capable of a
rapid cycling to interrupt flow of refrigerant to a lower stage
cylinder.
Inventors: |
Lifson; Alexander; (Manlius,
NY) ; Taras; Michael F.; (Fayetteville, NY) |
Assignee: |
CARRIER CORPORATION
Farmington
CT
|
Family ID: |
43499599 |
Appl. No.: |
13/384811 |
Filed: |
July 12, 2010 |
PCT Filed: |
July 12, 2010 |
PCT NO: |
PCT/US10/41691 |
371 Date: |
April 20, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61226824 |
Jul 20, 2009 |
|
|
|
Current U.S.
Class: |
62/228.5 ;
417/441 |
Current CPC
Class: |
F04B 27/24 20130101;
F04B 27/067 20130101; F04B 39/08 20130101; F04B 27/053 20130101;
F04B 35/01 20130101; F04B 49/03 20130101; F04B 2201/06011 20130101;
F04B 27/0673 20130101; F25B 2600/026 20130101; F25B 2400/074
20130101; F25B 2600/2521 20130101; F04B 39/1073 20130101; F04B
49/225 20130101; F04B 27/0451 20130101; F04B 49/22 20130101 |
Class at
Publication: |
62/228.5 ;
417/441 |
International
Class: |
F04B 49/03 20060101
F04B049/03; F25B 49/02 20060101 F25B049/02 |
Claims
1. A reciprocating compressor, the compressor comprising: a first
cylinder and a second cylinder; a first suction cutoff unloader
valve integral to the compressor and capable of rapid cycling to
interrupt flow of refrigerant to the first cylinder; a second
suction cutoff unloader valve assembly integral to the compressor
and capable of rapid cycling to interrupt flow of refrigerant to
the second cylinder; and a controller configured to operate at
least one of the first suction cutoff unloader valve assembly or
second suction cutoff unloader valve assembly in the rapid cycling
and monitor a number of rapid cycles for at least one suction
cutoff valve.
2. The reciprocating compressor of claim 1, wherein the compressor
includes three or more suction cutoff unloader assemblies and
wherein at least one of the suction cutoff unloader assemblies
operates in the rapid cycling while at least one of the suction
cutoff unloader assemblies does not operate in the rapid
cycling.
3. The reciprocating compressor of claim 1, wherein the rapid
cycling includes an alternating cycling mode that operates the
first suction cutoff unloader valve assembly in the rapid cycling,
while the second suction cutoff unloader valve assembly is not
operated in the rapid cycling but is disposed either in a fully
unloaded position blocking the flow of refrigerant to the second
cylinder or a fully loaded position allowing for uninterrupted flow
of refrigerant to the second cylinder.
4. The compressor of claim 3, wherein the controller operates the
first suction cutoff unloader valve assembly in the rapid cycling
for a first time period and the controller does not operate the
second suction cutoff unloader valve in the rapid cycling during
the first time period and then the controller operates the second
suction cutoff unloader valve assembly in the rapid cycling for a
second time period and does not operate the first suction cutoff
unloader valve assembly in the rapid cycling during the second time
period.
5. The reciprocating compressor of claim 1, wherein the controller
counts the number of cycles for each valve and alternates the first
and second suction cutoff unloader valve based on the count to
assure that the first suction cutoff unloader valve does not rapid
cycle a substantial number of times more than the second suction
cutoff unloader valve.
6. The compressor of claim 1, wherein the first and second suction
cutoff unloader valve assemblies have a cycle period of between 0.3
seconds and 180 seconds, when operated in the rapid cycling.
7. The compressor of claim 1, further comprising a third cylinder
and wherein the first cylinder is a lower stage cylinder and the
second cylinder is a lower stage cylinder and the reciprocating
compressor is a multi-stage compressor.
8. The compressor of claim 7, wherein both the first suction cutoff
unloader valve assembly and the second suction cutoff unloader
valve assembly operate simultaneously in the rapid cycling.
9. The compressor of claim 1, wherein rapid cycling is achieved
through pulse width modulation of the first and second suction
cutoff unloader valve assembly.
10. A reciprocating compressor, the compressor comprising: a first
cylinder and a second cylinder; a first suction cutoff unloader
valve assembly integral to the compressor and capable of rapid
cycling to interrupt flow of refrigerant to the first cylinder; a
second suction cutoff unloader valve assembly integral to the
compressor and capable of rapid cycling to interrupt flow of
refrigerant to the second cylinder; and a controller configured to
operate the first suction cutoff unloader valve assembly or second
suction cutoff unloader valve assembly in rapid cycling as an
alternating cycling mode which operates the first suction cutoff
unloader valve assembly in the rapid cycling while the second
suction cutoff unloader valve assembly is not operated in the rapid
cycling.
11. The compressor of claim 10, wherein the controller operates the
first suction cutoff unloader valve assembly in the rapid cycling
for a first time period and the controller does not operate the
second suction cutoff unloader valve in the rapid cycling during
the first time period and then the controller operates the second
suction cutoff unloader valve assembly in the rapid cycling for a
second time period and does not operate the first suction cutoff
unloader valve assembly in the rapid cycling during the second time
period.
12. The reciprocating compressor of claim 10, wherein the
controller counts the number of cycles for each valve and
alternates the first and second suction cutoff unloader valve based
on the count to assure that the first suction cutoff unloader valve
does not rapid cycle a substantial number of times more than the
second suction cutoff unloader valve.
13. The compressor of claim 10, wherein the first and second
suction cutoff unloader valve assembly have a cycle period of
between 0.3 seconds and 180 seconds, when operated in rapid
cycling.
14. The compressor of claim 10, further comprising a third higher
stage cylinder and wherein the first cylinder is a lower stage
cylinder and the second cylinder is a lower stage cylinder and the
reciprocating compressor is a multi-stage compressor.
15. The compressor of claim 10, wherein rapid cycling is achieved
through pulse width modulation of the first and second suction
cutoff unloader valve assembly.
16. A multi-stage reciprocating compressor, the compressor
comprising: a lower stage cylinder and a higher stage cylinder, the
higher stage arranged to receive refrigerant compressed in the
lower stage cylinder; at least one suction cutoff unloader valve
assembly integral with compressor and capable of rapid cycling to
interrupt flow of refrigerant to the lower stage cylinder; and a
controller configured to operate the at least one suction cutoff
unloader valve assembly in the rapid cycling.
17. The compressor of claim 15, wherein the at least one suction
cutoff unloader valve assembly has a cycle period of between 0.3
second and 180 seconds, when operated in rapid cycling.
18. The compressor of claim 15, wherein rapid cycling is achieved
through pulse width modulation of the first suction cutoff unloader
valve assembly.
19. The multi-stage compressor of claim 15, further comprising: a
second lower stage cylinder; and a second suction cutoff unloader
valve assembly capable of rapid cycling to interrupt flow of
refrigerant to the second lower stage cylinder.
20. The multi-stage compressor of claim 18, wherein the controller
operates both the first suction cutoff unloader valve assembly and
the second suction cutoff unloader valve assembly simultaneously in
rapid cycling.
Description
BACKGROUND
[0001] Refrigeration and air conditioning systems are commonly
configured with means for system capacity control, thereby allowing
the systems to improve temperature control accuracy, reliability,
and energy efficiency.
[0002] Currently the most common means of refrigeration and air
conditioning system capacity control is accomplished by unit
cycling (turning the compressor on and off in response to
fluctuations in temperature or system pressure). However, unit
cycling does not allow for tight temperature control, and
therefore, commonly creates discomfort and/or undesired temperature
variations in the conditioned/refrigerated space.
[0003] A suction modulation valve located on a suction line
downstream of the compressor is another means commonly utilized for
system capacity control. However, suction modulation valves are
expensive and are inefficient for system capacity control.
[0004] To overcome this, suction cutoff unloader valves integral to
the compressor have been developed. One such suction cutoff
unloader valve is disclosed in United States Patent Application
Publication Number 2006/0218959 to Sandkoetter. Unfortunately, the
suction cutoff unloader valve disclosed in Sandkoetter is adapted
to be operable only in a single stage compressor, where compression
is accomplished only by lower stage cylinders operating in
parallel. Also, Sandkoetter discloses that all cylinder units 44
have the same switching intervals in a lower part-load range and
that all the suction cutoff unloader valves are preferably operated
with the same switching intervals in an upper part-load range to
avoid balancing problems with the compressor pistons. By operating
all the valves with the same switching intervals in either the
lower or upper part-load range can greatly reduce the service life
of the suction cutoff unloader valves as each valve must be opened
and closed even when a reduced compressor capacity could be
achieved by operating only a single valve. In the Sandkoetter
application, there is also no counting or monitoring of the number
of the cycles for any of the valves. Thus, it would be impossible
to distribute the cycling duty between the valves.
SUMMARY
[0005] A reciprocating compressor includes a first cylinder and a
second cylinder, first and second suction cutoff unloader valve
assemblies, and a controller. The first and second suction cutoff
unloader valve assemblies are integral to the compressor and are
capable of rapid cycling to interrupt flow of refrigerant to the
first and second cylinders. The controller is configured to operate
at least one of the first suction cutoff unloader valve assembly
and second suction cutoff unloader valve assembly in the rapid
cycling and to monitor a number of rapid cycles for at least one
suction cutoff unloader valve. In another aspect, a multi-stage
compressor, with at least one stage being a low pressure stage and
at least one other stage being a high pressure stage, has at least
one suction cutoff unloader valve assembly capable of rapid cycling
to interrupt flow of refrigerant to a lower stage cylinder or
cylinders. The multi-stage compressor has a controller configured
to operate the at least one suction cutoff unloader valve assembly
on the lower stage in the rapid cycling.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] FIG. 1A is a cross-sectional view of one embodiment of a
reciprocating compressor with high and low compression stages and
with a controller electrically connected to suction cutoff unloader
valve assemblies.
[0007] FIG. 1B is a cross-sectional view of another embodiment of a
reciprocating compressor with the controller electrically connected
to the suction cutoff unloader valve assemblies.
[0008] FIG. 2A is a partial sectional view of the suction cutoff
unloader valve assembly, a cylinder head, and a cylinder block of
the compressor of FIG. 1A or FIG. 1B with the suction cutoff
unloader valve assembly in a fully loaded position.
[0009] FIG. 2B is a partial sectional view of the cylinder block,
cylinder head, and suction cutoff unloader valve assembly of the
compressor of FIG. 1A or FIG. 1B with the suction cutoff unloader
valve assembly in a fully unloaded position.
[0010] FIG. 3A is a partial sectional view of a portion of the
suction cutoff unloader valve assembly and cylinder head in the
fully loaded position of FIG. 2A.
[0011] FIG. 3B is a partial sectional view of a portion of the
suction cutoff unloader valve assembly and cylinder head in the
fully unloaded position of FIG. 2B.
DETAILED DESCRIPTION
[0012] FIG. 1A shows a cross-section of a multi-stage reciprocating
compressor 10M with a controller 12 is electrically connected to
suction cutoff unloader valve assembly(s) 14. In the multi-stage
compressor, the compression is accomplished in two steps, where the
first stage of compression (from the suction pressure to
intermediate pressure) is accomplished by the lower stage
cylinder(s) and the second stage of compression (from the
intermediate pressure to discharge pressure) is accomplished by
higher stage cylinder(s). In addition to the suction cutoff
unloader valve assemblies 14, the compressor 10 includes lower
stage cylinder heads 16L, a higher stage cylinder head 16H, a
housing 18, a cylinder block 20, lower stage cylinder banks 22L, a
higher stage cylinder bank 22H, lower stage cylinders 24L, a higher
stage cylinder 24H, pistons 26, connecting rods 28, a crankshaft
30, an oil sump 32, a suction manifold 34, and an intermediate
manifold 36. Each of the lower and higher stage cylinder heads 16L
and 16H includes a suction plenum 38 and a plenum 40.
[0013] The multi-stage reciprocating compressor 10M has suction
cutoff unloader valve assembly or assemblies 14 which interconnect
with the low stage cylinder heads 16L. At least one suction cut off
assembly 14 is capable of operating in a rapid cycle mode. It
should noted that the multi-stage compressor 10M can have one
suction cutoff assembly 14 and this one assembly 14 can be capable
of operating in the rapid cycle mode. In embodiments such as the
one illustrated in FIG. 1A, the compressor 10M can have two or more
suction cutoff unloader valve assemblies 14, where both suction
cutoff valve assemblies are operating in rapid cycle mode, or only
one suction cut off assembly 14 is operating in rapid cycle mode.
The suction cutoff unloader valve assemblies 14 are integral to the
compressor 10M. The housing 18 of the multi-stage compressor 10M
has an upper portion of which forms the cylinder block 20. The
cylinder block 20 forms one or more low lower stage cylinder banks
22L, as well as the higher stage cylinder bank 22H. The cylinder
block 20 defines lower stage cylinders 24L and a higher stage
cylinder 24H. The cylinders 24L and 24H, which extend through the
cylinder block 20, are disposed adjacent to the cylinder heads 16L
and 16H and the suction cutoff unloader valve assemblies 14. The
lower stage cylinder heads 16L are secured to the cylinder block 20
overlaying the lower stage cylinders 24L in the low stage cylinder
banks 22L. Similarly, the higher stage cylinder head 16H is secured
to the cylinder block 20 overlaying the higher stage cylinders 24H
in the higher stage cylinder bank 22H. Each cylinder bank 22L or
22H includes at least one cylinder 24L or 24H and may include
multiple cylinders 24L or 24H which are overlaid by cylinder head
16L or 16H.
[0014] The pistons 26 are disposed in the lower and higher stage
cylinders 24L and 24H and are reciprocally movable therein. The
pistons 26 interconnect with the connecting rods 28 which extend
internally within the multi-stage compressor 10M to interconnect
with an eccentric portion of the crankshaft 30. The crankshaft 30
is rotatably disposed internally in the compressor 10M and extends
through the oil sump 32. The suction manifold 34 and intermediate
manifold 36 are defined by the cylinder block 20. The suction
manifold 34 communicates with the oil sump 32 or directly with a
suction line (not shown). The suction manifold 34 extends to the
lower stage cylinder heads 16L to fluidly communicate with the
suction plenum 38 in each cylinder head 16L.
[0015] In one embodiment, when the compressor 10M is in a fully
loaded mode of operation, i.e. all the suction cutoff unloader
valve assemblies 14 are constantly off and, are therefore, not
cycling in a pulse width modulated manner, a low pressure
refrigerant enters the multi-stage compressor 10M from the suction
line (not shown) through an inlet port (not shown). Reviewing the
operation of a single cylinder bank 22L, the reciprocating movement
of the piston(s) 26 within the low stage cylinder(s) 24L draws the
refrigerant from the suction line (not shown). The refrigerant is
drawn into the suction manifold 34, and from there the refrigerant
is drawn into the suction plenum 38 in the lower stage cylinder
head 16L. From the suction plenum 38 the refrigerant passes into
the low stage cylinder 24L (or cylinders) where it is compressed by
the piston(s) 26. A reed valve (not shown) is positioned above each
lower stage cylinder 24L to control the flow of refrigerant
thereto. After leaving the lower stage cylinder 24L (or cylinders)
the higher pressure vapor refrigerant is discharged through another
reed valve (not shown) into the plenum 40. In the fully loaded
mode, a first portion of the suction cutoff unloader valve 14
fluidly communicates with the plenum 40 and is configured to allow
the refrigerant (at intermediate discharge pressure) to hold open a
piston portion of the suction cutoff unloader valve 14 to permit
the flow of the refrigerant through the suction plenum 38 to the
lower stage cylinder(s) 24L. From the plenum 40 of the lower stage
cylinder heads 16L the intermediate pressure refrigerant eventually
passes to the intermediate manifold 36. The intermediate pressure
refrigerant is drawn from the intermediate manifold 36 to the
suction plenum 38 of the higher stage cylinder head 16H where
compression of the refrigerant in the higher stage cylinder 24H (or
cylinders) is repeated. However, no suction cutoff unloader valve
14 is necessary on the higher stage cylinder head 16H. It should be
understood that the number of suction cutoff unloader valve
assemblies can be equal to one or can be multiple assemblies. The
number of lower stage cylinders can also be equal to one, but it
can also can be multiple cylinders. One unloader valve assembly can
also control the flow to one or multiple cylinders.
[0016] When the multi-stage reciprocating compressor 10M is in a
fully unloaded mode, i.e. all the suction cutoff unloader valve
assemblies 14 are constantly on and, are therefore, not cycling in
a pulse width modulated manner. In this case, the first portion of
each of the suction cutoff unloader valve assemblies 14 is disposed
to block flow of the refrigerant from the plenum 40 to the piston
portion of the suction cutoff unloader valve assembly 14. This
configuration allows the biased piston portion of the suction
cutoff unloader valve assembly 14 to move to a position where it
substantially halts the flow of the refrigerant through the suction
plenum 38 to the lower stage cylinder(s) 24L.
[0017] As will be discussed in greater detail subsequently, the
controller 12 can be provided with control logic which allows one
or more of the suction cutoff unloader valve assemblies 14 on the
first stage of the multi-stage compressor 10M to be operated in
rapid cycling (for example, using a pulse width modulation
technique) to provide a continuously variable amount of capacity
(part-load operation) between the capacity achieved by the
multi-stage compressor 10M when the suction cutoff unloader valve
assemblies 14 are in the fully unloaded position, and the capacity
achieved by the multi-stage compressor 10M when the suction cutoff
unloader valve assemblies 14 are in the fully loaded position. In
one arrangement the low pressure stage can have of only one suction
cutoff valve assembly and only one cylinder, where the suction
cutoff valve is capable of operating in a rapid cycle mode. If the
first stage is provided with multiple suction cutoff valves, then
the controller 12 can also be provided with control logic which
allows a first suction cutoff unloader valve assembly 14 and a
second suction cutoff unloader valve assembly 14 to alternate rapid
cycling in a mode that allows one of the suction cutoff unloader
valve assemblies 14 to operate in rapid cycling while the other
suction cutoff unloader valve assembly 14 is not operated in rapid
cycling but is disposed in the fully loaded position or the fully
unloaded position. For example, the first suction cutoff unloader
valve assembly 14 can operate in rapid cycling for a first time
period. During the first time period, the second suction cutoff
unloader valve assembly 14 is not operated in rapid cycling. At the
end of the first time period the second suction cutoff unloader
valve assembly 14 is then operated in rapid cycling for a second
time period. During that second time period, the first suction
cutoff unloader valve assembly 14 is not operated in rapid cycling.
In this manner, the suction cutoff unloader valve assemblies 14 can
be alternated in rapid cycling to achieve continuously variable
part-load system capacity.
[0018] If the lower stage is equipped with only one suction cutoff
valve, then this valve can be operated in a rapid cycle mode. If
there is more than one suction cut off valve installed on the lower
stage, then the pattern of changing the suction cutoff unloader
valve assembly 14 that is operated in rapid cycling while the other
valve or valves, if present, are not operated in rapid cycling can
be repeated for each valve in the compressor 10M. The alternating
sequence can be modified, for example, instead of a single suction
cutoff unloader valve assembly 14 that is operated in rapid
cycling, multiple suction cutoff unloader valve assemblies 14 can
be operated in rapid cycling while a single (or multiple) suction
cutoff unloader valve assembly 14 is not operated in rapid cycling.
In yet another embodiment, all the suction cutoff unloader valve
assemblies 14 in the compressor 10M can be operated in rapid
cycling to achieve part-load system capacities.
[0019] In one embodiment, one or more suction cutoff unloader valve
assemblies 14 can achieve part-load system operation by rapid
cycling between the fully loaded position and the fully unloaded
position with a single cycle period that is between 0.3 second and
180 seconds. This cycle period is short enough to account for the
inertia of the reaction of the refrigeration or air conditioning
system. The operation of the suction cutoff unloader valve
assemblies during the cycle period may vary. For example, within
180 second period, one suction cutoff unloader valve assembly 14
can be operated at the fully loaded position (or nearly fully
loaded position) for 10 seconds and then operated at the fully
unloaded (or nearly fully unloaded position) position for 170
seconds. Alternatively, the suction cutoff unloader valve assembly
14 can be operated at the fully unloaded position for 20 seconds
and then operated at the fully loaded position for 160 seconds.
Thus, various different operation patterns during a single cycle
period are possible. In yet another example, the suction cutoff
unloader valve assembly 14 operates with a 5 second cycle period.
In this embodiment, the suction cutoff unloader valve assembly 14
can be operated at the fully loaded position for 1 second and then
operated at the fully unloaded position for 4 seconds.
Alternatively, the suction cutoff unloader valve assembly 14 can be
operated at the fully unloaded position for 2 seconds and then
operated at the fully loaded position for 3 seconds, etc. As
illustrated with these examples, various patterns of suction cutoff
unloader valve assembly operation resulting in different levels of
unloading of the compressor can be achieved, even when identical
cycle periods are utilized by the suction cutoff unloader valve
assembly. Due to the rapid pulse width modulation of one or more of
the valves, only small temperature fluctuations occur in the
evaporator (not shown). These temperature fluctuations do not
impair precise temperature control of the conditioned space.
[0020] As compared to FIG. 1A, which shows a compressor 10M that
has lower and higher compression stages, in FIG. 1B, a compressor
10S has at least two suction cutoff valve assemblies 14 that are
capable of operation in rapid cycle mode. This embodiment monitors
the number of cycles for the at least two suction cutoff valve
assemblies 14. By monitoring the number of cycles for the at least
two suction cutoff valve assemblies 14 the controller 12 can adjust
the amount of rapid cycles each valve undergoes. Thus the rapid
cycling can be split between the valves to increase the longevity
of the at least two suction cutoff valve assemblies 14.
[0021] FIG. 1B shows a cross-section of a single low stage
compression reciprocating compressor 10S with a controller 12
electrically connected to multiple suction cutoff unloader valve
assemblies 14. It should be understood that the single low stage
compressor can have more than one low stage compression stages
connected in parallel to each other in other embodiments. In
addition to the suction cutoff unloader valve assemblies 14, the
compressor 10 includes cylinder heads 16L, the housing 18, the
cylinder block 20, cylinder banks 22L, cylinders 24L, pistons 26,
connecting rods 28, the crankshaft 30, the oil sump 32, and the
suction manifold 34. Each of the cylinder heads 16L includes the
suction plenum 38 and the plenum 40. The compressor 10S includes a
discharge manifold 42.
[0022] More particularly, the single stage reciprocating compressor
10S has suction cutoff unloader valve assemblies 14 which
interconnect with the cylinder heads 16L. The housing 18 of the
compressor 10S has an upper portion of which forms the cylinder
block 20. The cylinder block 20 forms one or more cylinder banks
22L. The cylinder block 20 defines cylinders 24L. The cylinders
24L, which extend through the cylinder block 20, are disposed
adjacent to the cylinder heads 16L. The cylinder heads 16L are
secured to the cylinder block 20 overlaying the cylinders 24L in
the cylinder banks 22L. Each cylinder bank 22L includes at least
one cylinder 24L and may include multiple cylinders 24L which are
overlaid by cylinder head 16L.
[0023] The pistons 26 are disposed in the cylinders 24L and are
reciprocally movable therein. The pistons 26 interconnect with the
connecting rods 28 which extend internally within the single stage
compressor 10S to interconnect with an eccentric portion of the
crankshaft 30. The crankshaft 30 is rotatably disposed internally
in the compressor 10S and extends through the oil sump 32, which is
optional but illustrated in the embodiment shown in FIG. 1B. The
suction manifold 34 and discharge manifold 42 are defined by the
cylinder block 20. Each of the cylinder heads 16L has a suction
plenum 38 and plenum 40 therein which selectively communicate with
the underlying cylinders 24L during a portion of the stroke of the
pistons 26.
[0024] The suction manifold 34 communicates with the oil sump 32 or
directly with a suction line (not shown). The suction manifold 34
extends to the cylinder heads 16L to fluidly communicate with the
suction plenum 38 in each cylinder head 16L. The discharge manifold
42 selectively fluidly communicates with the plenum 40 through
ports in the valve plate. The discharge manifold 42 also fluidly
communicates a discharge line (not shown) to allow refrigerant
discharged from the cylinders 24L to pass to the other components
of the heating or cooling system.
[0025] The suction cutoff unloader valve assemblies 14 of the
compressor 10S are capable of operating in a manner similar to that
of the suction cutoff unloader valve assemblies 14 of the
multi-stage compressor 10M shown in FIG. 1A. Thus, when the
compressor 10S is in a fully loaded mode of operation, i.e. all the
suction cutoff unloader valve assemblies 14 are activated but are
not cycling in a pulse width modulated mode. Reviewing the
operation of a single cylinder bank 22L, refrigerant is drawn
through the suction manifold 34, and from there into the suction
plenum 38 in the cylinder head 16L. From the suction plenum 38 the
refrigerant passes into the cylinder 24L (or cylinders) where it is
compressed by the piston(s) 26. After leaving the cylinder 24L (or
cylinders) the higher pressure vapor refrigerant enters the plenum
40. In the fully loaded mode, a first portion of the suction cutoff
unloader valve 14 fluidly communicates with the plenum 40 and is
positioned to allow the refrigerant (at discharge pressure) to
force open a piston portion of the suction cutoff unloader valve 14
to permit the flow of the refrigerant through the suction plenum 38
to the cylinder 24L. From the plenum 40 of the cylinder head 16L
the refrigerant passes to the discharge manifold 42. From the
discharge manifold 42 the compressed refrigerant exits the
compressor 10S through an outlet port (not shown) to other
components of the heating or cooling system.
[0026] When the single stage reciprocating compressor 10S is in a
fully unloaded mode, i.e. all the suction cutoff unloader valve
assemblies 14 are constantly on and, are therefore, not cycling in
a pulse width modulated manner, the compressor 10S operates as
described above until the point at which the compressed refrigerant
is discharged from the cylinder 24L (or cylinders) into the plenum
40. Because all the suction cutoff unloader valve assemblies 14 are
deactivated, the first portion of each of the suction cutoff
unloader valve assemblies 14 is disposed to block discharge flow of
the refrigerant from the plenum 40 to the piston portion of the
suction cutoff unloader valve assembly 14. This configuration
allows the biased piston portion of the suction cutoff unloader
valve assembly 14 to move to a position where it substantially
halts the flow of the refrigerant through the suction plenum 38 to
the cylinder(s) 24L.
[0027] The controller 12 can be provided with control logic which
allows a first suction cutoff unloader valve assembly 14 and a
second suction cutoff unloader valve assembly 14 to alternate rapid
cycling in a mode that allows one of the suction cutoff unloader
valve assemblies 14 to operate in rapid cycling while the other
suction cutoff unloader valve assembly 14 is not operated in rapid
cycling but is disposed in the fully loaded position or the fully
unloaded position. For example, the first suction cutoff unloader
valve assembly 14 can operate in rapid cycling for a first time
period. During the first time period, the second suction cutoff
unloader valve assembly 14 is not operated in rapid cycling. At the
end of the first time period the second suction cutoff unloader
valve assembly 14 is then operated in rapid cycling for a second
time period. During that second time period, the first suction
cutoff unloader valve assembly 14 is not operated in rapid cycling.
In this manner, the suction cutoff unloader valve assemblies 14 can
be alternated in rapid cycling to achieve continuously variable
part-load system capacity. Alternating the cycles of the valve
assemblies can be achieved by the controller 12, which monitors and
counts the number of rapid cycles for each valve and alternates the
first and second suction cutoff unloader valve assemblies 14 based
on the count to assure that the first suction cutoff unloader valve
assembly 14 is not operated in a rapid cycling mode for a
substantially higher number of cycles more than the second suction
cutoff unloader valve assembly 14. In this manner, wear on any
single valve assembly due to rapid cycling can be reduced. It is
possible for a controller 12 to only count the number of cycles on
one valve assembly 14 and when the number of cycles approaches a
limit on this valve, the other valve would then be operated in the
rapid cycling mode, while the first valve would stop operating in
the rapid cycling mode. The counting does not need to be direct
but, for example, can be estimated based on the number of days the
compressor is in service or the number of hours the compressor has
been operational, etc. In this case, for example, the switching
between the valves can be done based on how many days one valve was
operating in the rapid cycling mode versus the other valve.
Alternating the cycling of the valves reduces the overall number of
cycles each valve experiences to achieve the desired system
part-load capacity. Thus, the service life of the suction cutoff
unloader valves and reliability of the compressor can be increased
via alternating the cycling of the valves.
[0028] One or more of the suction cutoff unloader valve assemblies
14 of the single stage compressor 10S can be operated in a pulse
width modulation mode to provide a continuously variable capacity
(part-load mode of operation) between the capacity achieved by the
single stage compressor 10S when the suction cutoff unloader valve
assemblies 14 are in the fully unloaded position, and the capacity
achieved by the single stage compressor 10S when the suction cutoff
unloader valve assemblies 14 are in the fully loaded position. The
controller 12 can also be provided with control logic which allows
rapid cycling of a first suction cutoff unloader valve assembly 14
and a second suction cutoff unloader valve assembly 14 to alternate
in rapid cycling such that while one of the suction cutoff unloader
valve assemblies 14 operates in rapid cycling the other suction
cutoff unloader valve assembly 14 is not operated in rapid cycling
but is disposed in the fully loaded position or fully unloaded
position. The pattern, sequence, and number of suction cutoff
unloader valve assemblies 14 alternated can be altered in the
manner discussed above with reference to the multi-stage compressor
10M (FIG. 1A).
[0029] FIG. 2A is a partial sectional view of a portion of the
compressor 10S or 10M with the suction cutoff unloader valve
assembly 14 in a fully loaded position. FIG. 2B is a partial
sectional view of a portion of the compressor 10S or 10M with the
suction cutoff unloader valve assembly 14 in a fully unloaded
position. In addition to the suction cutoff unloader valve assembly
14, lower stage cylinder head 16L, cylinder block 20, lower stage
cylinder 24L, piston 26, and suction manifold 34, the compressor
10S or 10M includes a valve plate 44, fasteners 46, suction ports
48A and 48B, a suction valve 50, discharge ports 52A and 52B, a
discharge valve 54, and a channel port 56. In addition to the
suction plenum 38 and plenum 40, the cylinder head 16 includes a
channel 58, guide walls 60, and a suction cutoff wall 62. The
suction cutoff unloader valve assembly 14 includes the channel 58,
channels 58A and 58B, a pressure chamber 64, a piston chamber 66, a
valve piston 68, a valve 70, a solenoid 72, a valve body 74, and a
bias spring 76.
[0030] In FIGS. 2A and 2B, the lower stage cylinder head 16L
overlays the cylinder block 20 and the lower stage cylinder 24L.
The valve plate 44 is disposed between the cylinder block 20 and
the lower stage cylinder head 16L. The fasteners 46 secure the
lower stage cylinder head 16L to the cylinder block 20. The valve
plate 44 defines suction ports 48A and 48B. Suction port 48A
extends through the valve plate 44 between the suction manifold 34
and the suction plenum 38. Suction port 48B extends through the
valve plate 44 between the suction plenum 38 and the lower stage
cylinder 24L. The suction valve 50 connects to the valve plate 44
and selectively covers the suction port 48B. The suction valve 50
is selectively movable from over the suction port 48B to allow
refrigerant to enter the lower stage cylinder 24L. The discharge
port 52A extends through the valve plate 44 between the lower stage
cylinder 24L and the plenum 40. Discharge valve 54 connects to the
valve plate 44 and interacts with the valve plate 44 to selectively
cover and uncover the discharge port 52A. Discharge port 52B
extends through the valve plate 44 between the plenum 40 and the
intermediate or discharge manifold 36 or 42.
[0031] Channel port 56 extends through the lower stage cylinder
head 16L to allow the channel 58 to communicate with the plenum 38.
The channel 58 extends through the casing of the lower stage
cylinder head 16L and stator casing portion of the suction cutoff
unloader valve assembly 14. The guide walls 60 are internal walls
in the lower stage cylinder head 16L which are sized to receive a
movable portion of the suction cutoff unloader valve assembly 14.
Similarly, the suction cutoff wall 62 is disposed adjacent the
suction port 48A to extend into the suction plenum 38. The suction
cutoff wall 62 interacts with another movable portion of the
suction cutoff unloader valve assembly 14 to halt the flow of
refrigerant through the suction plenum 38 to the lower stage
cylinder 24L.
[0032] The channel 58 extends from the plenum 40 (through channel
port 56) to the pressure chamber 64. The channel 58A extends from
pressure chamber 64 through the stator portion of the suction
cutoff valve assembly 14 to the suction plenum 38 (around the guide
wall 60), while the channel 58B extends from the pressure chamber
64 through the stator portion of the suction cutoff valve assembly
14 to communicate with the piston chamber 66. The valve piston 68
is received between the guide walls 60 (which define the piston
chamber 66) and is movable relative thereto. The valve 70 extends
through the pressure chamber 64 and interconnects with the solenoid
72 which movably actuates the valve 70 within the pressure chamber
64. The valve 70 blocks channel 58 from fluid communication with
the pressure chamber 64 when the suction cutoff valve assembly 14
enters the fully unloaded position. The valve 70 blocks channel 58A
from fluid communication with the pressure chamber 64 when the
suction cutoff valve assembly 14 enters the fully loaded
position.
[0033] The piston chamber 66 receives the valve piston 68 therein.
The valve piston 68 connects to the valve body 74 which extends
through the suction plenum 38. The portion of the valve body 74
extending away from the valve piston 68 is configured to receive
the bias spring 76. The bias spring 76 is disposed in the suction
plenum 38 and contacts the valve body 74 and the wall of the low
stage cylinder head 16L.
[0034] In FIGS. 2A and 2B, the suction port 48A provides a pathway
for refrigerant to fluidly communicate from the suction manifold 34
to the suction plenum 38. Suction port 48B provides a pathway for
refrigerant to be drawn by reciprocation of the piston 26 from the
suction plenum 38 to the lower stage cylinder 24L. The suction
valve 50 selectively covers the suction port 48B to substantially
block fluid communication of the refrigerant from the suction
plenum 38 to the lower stage cylinder 24L and is selectively
movable from over the suction port 48B to allow refrigerant to
enter the lower stage cylinder 24L during a suction portion of the
piston 26 stroke. The discharge port 52A allows higher pressure
compressed refrigerant to fluidly communicate from the lower stage
cylinder 24L to the plenum 40 during the discharge stroke of the
piston 26. The discharge valve(s) 54 selectively covers the
discharge port(s) 52A to substantially block fluid communication of
the refrigerant from the lower stage cylinder 24L to the plenum 40
until the refrigerant is a sufficient pressure to raise the
discharge valve(s) 54 away from the valve plate 44. Discharge port
52B provides a pathway for compressed refrigerant to fluidly
communicate from the plenum 40 to the intermediate or discharge
manifold 36 or 42.
[0035] The channel 58 extends from the plenum 40 (through channel
port 56) to the pressure chamber 64 to allow refrigerant to
communicate therewith. In the fully loaded position illustrated in
FIG. 2A, the channel 58A extending from the pressure chamber 64 to
the suction plenum 38 is substantially blocked by the valve 70
which is actuated into this blocking position by the solenoid 72.
Thus, the refrigerant is directed from the plenum 40 through the
channel 58 to the pressure chamber 64, and from the pressure
chamber 64 through channel 58B into the piston chamber 66. The
compressed high pressure refrigerant causes the internal pressure
to build within the piston chamber 66 to a level sufficient to
overcome the bias on the valve body 74 by the bias spring 76. When
overcoming this bias, the valve piston 68 and valve body 74 move
within the piston chamber 66 and suction plenum 38 to a position
which allows refrigerant to flow through the suction plenum 38
between the valve body 74 and the suction cutoff wall 62, such that
the refrigerant can communicate with the low stage cylinder 24L
through the suction port(s) 48B.
[0036] In the fully unloaded position illustrated in FIG. 2B, the
solenoid 72 actuates the valve 70 away from a position which blocks
communication of refrigerant through channel 58A. The actuation of
the valve 70 moves the valve 70 to a position which blocks
communication of refrigerant through channel 58. Thus, high
pressure compressed refrigerant is substantially blocked from
entering the piston chamber 66. The refrigerant in the piston
chamber 66 is decreased in pressure by communication between the
suction plenum 38 and piston chamber 66 (through channels 58A and
58B) and by a bleed orifice (not shown), which allows the
refrigerant to bleed from the piston chamber 66 back into the
channel 58.
[0037] By decreasing the pressure in the piston chamber 66, the
pressure exerted on the valve piston 68 is insufficient to overcome
the bias of the bias spring 76. The bias spring 76 moves the valve
piston 68 and valve body 74 within the piston chamber 66 and
suction plenum 38 to a position which substantially halts the flow
of refrigerant through the suction plenum 38 between the valve body
74 and the suction cutoff wall 62. Thus, the configuration and
arrangement of the valve body 74 and suction cutoff wall 62 do not
allow for the flow of refrigerant to the lower stage cylinder 24L
when the suction cutoff valve assembly 14 is in the fully unloaded
position.
[0038] As discussed previously, the suction cutoff unloader valve
assemblies 14 can be operated in a pulse width modulation mode to
provide a continuously variable capacity (part-load mode of
operation) between the capacity achieved by the compressor 10
(FIGS. 1A and 1B) when the suction cutoff unloader valve assembly
14 is in the fully unloaded mode, and the capacity achieved by the
compressor 10S or 10M when the suction cutoff unloader valve
assembly 14 is in the fully loaded position. More specifically, the
solenoid 72 can be activated by the controller 12 (FIGS. 1A and 1B)
to operate in a pulse width modulation mode and provide for a
continuously variable capacity by moving the valve 70 to block and
unblock the channels 58 and 58A in a rapid fashion to
allow/disallow communication between the plenum 40 and the piston
chamber 66 (and thereby cause valve piston 68 and valve body 74 to
move relative to the suction cutoff wall 62 to block/unblock the
flow of refrigerant through the suction plenum 38 to the lower
stage cylinder 24L). The solenoid 70 can cycle between the fully
loaded position of FIG. 2A, and the fully unloaded position of FIG.
2B, either rapidly or more slowly as dictated by the inertia of the
system. In one embodiment, the cycle period of the suction cutoff
unloader valve assembly 14 and solenoid 72 is between 0.3 second
and 180 seconds. In another embodiment, the cycle period is between
3 seconds and 30 seconds. In yet another embodiment, the cycle
period of the suction cutoff unloader valve assembly 14 is
approximately 15 seconds.
[0039] Pulse width modulation of the solenoid 72 of the suction
cutoff unloader valve assembly 14 allows for greater compressor 10
capacity control, thereby allowing the suction cutoff unloader
valve assembly 14 to dial in on a desired compressor 10 capacity.
Greater compressor 10 capacity control allows the refrigeration or
air conditioning system to achieve improved temperature control
accuracy, reliability, and energy efficiency.
[0040] As discussed previously, the controller 12 (FIGS. 1A and 1B)
can also be provided with control logic which allows a first
suction cutoff unloader valve assembly 14 and a second suction
cutoff unloader valve assembly 14 to alternate cycling modes such
that while one of the suction cutoff unloader valve assemblies 14
operates in the pulse width modulated mode the other suction cutoff
unloader valve assembly 14 is not operated in the pulse width
modulation mode but is disposed in the fully loaded position or the
fully unloaded position. The pattern, sequence, and number of
suction cutoff unloader valve assemblies 14 alternated can be
altered in the manner discussed above with reference to the
multi-stage compressor 10M (FIG. 1A).
[0041] FIG. 3A shows a portion of the suction cutoff unloader valve
assembly 14 and lower stage cylinder head 16L in the fully loaded
position. FIG. 3B shows the portion of the suction cutoff unloader
valve assembly 14 and lower stage cylinder head 16L in the fully
unloaded position. The low stage cylinder head 16L includes the
suction plenum 38, the channel 58, and guide walls 60. In addition
to the channel 58, the channels 58A and 58B, the pressure chamber
64, the piston chamber 66, the valve piston 68, the valve 70, and
the solenoid 72, the suction cutoff unloader valve assembly 14
includes a movable bias member 78 and a bleed orifice 80.
[0042] Channel port 56 extends through the low stage cylinder head
16L to allow the channel 58 to communicate with the plenum 40. The
channel 58 extends through the casing of the lower stage cylinder
head 16L and stator casing portion of the suction cutoff unloader
valve assembly 14. The guide walls 60 are internal walls in the low
stage cylinder head 16L are sized to receive a movable portion of
the suction cutoff unloader valve assembly 14. Similarly, the
suction cutoff wall 62 is disposed adjacent suction port 48A to
extend into the adjacent suction plenum 38. The suction cutoff wall
62 interacts with another movable portion of the suction cutoff
unloader valve assembly 14 to halt the flow of refrigerant through
the suction plenum 38 to the lower stage cylinder 24L.
[0043] The channel 58 extends from the plenum 40 (through channel
port 56) to the pressure chamber 64. The channel 58A extends from
pressure chamber 64 through the stator portion of the suction
cutoff valve assembly 14 to the suction plenum 38 (around the guide
wall 60), while the second channel 58B extends from the pressure
chamber 64 through the stator portion of the suction cutoff valve
assembly 14 to communicate with the piston chamber 66. The valve
piston 68 is received between the guide walls 60 (which define the
piston chamber 66) and is movable relative thereto. The valve 70
extends through the pressure chamber 64 and interconnects with the
movable bias member 78 portion of solenoid 72 which actuates the
valve 70 within the pressure chamber 64. The valve 70 blocks
channel 58 from fluid communication with the pressure chamber 64
when the suction cutoff valve assembly 14 enters the fully unloaded
position. The valve 70 blocks channel 58A from fluid communication
with the pressure chamber 64 when the suction cutoff valve assembly
14 enters the fully loaded position. The bleed orifice 80 extends
into the stator portion of the suction cutoff unloader valve
assembly 14 and communicates with the channel 58.
[0044] The channel 58 extends from the plenum 40 (through channel
port 56) to the pressure chamber 64 to allow refrigerant to
communicate therewith. In the fully loaded position illustrated in
FIG. 3A, the channel 58A extending from the pressure chamber 64 to
the suction plenum 38 is substantially blocked by the valve 70
which is actuated into this blocking position by the solenoid 72.
Thus, the refrigerant is directed from the plenum 40 through
channel 58 to the pressure chamber 64, and from the pressure
chamber 64 through channel 58B into the piston chamber 66. The
compressed high pressure refrigerant causes the internal pressure
to build within the piston chamber 66 to a level sufficient to
overcome the bias on the valve body 74 by the bias spring 76 (FIG.
2A). When overcoming this bias, the valve piston 68 and valve body
74 moves within the piston chamber 66 and suction plenum 38 to a
position which allows refrigerant to flow through the suction
plenum 38 between the valve body 74 and the suction cutoff wall 62
such that the refrigerant can communicate with the low stage
cylinder 24L through the suction port(s) 48B (FIG. 2A).
[0045] In the fully unloaded position illustrated in FIG. 3B, the
solenoid 72 actuates the valve 70 away from a position which blocks
communication of refrigerant through channel 58A. The actuation of
the valve 70 moves the valve 70 to a position which blocks
communication of refrigerant through channel 58. Thus, high
pressure compressed refrigerant is substantially blocked from
entering the piston chamber 66. The refrigerant in the piston
chamber 66 is decreased in pressure by communication between the
suction plenum 38 and piston chamber 66 (through channels 58A and
58B) and by a bleed orifice 80 which allows the refrigerant to
bleed in one direction from the piston chamber 66 back into the
channel 58.
[0046] By decreasing the pressure in the piston chamber 66, the
pressure exerted on the valve piston 68 is insufficient to overcome
the bias of the bias spring 76 (FIG. 2B). The bias spring 76 moves
the valve piston 68 and valve body 74 within the piston chamber 66
and suction plenum 38 to a position which substantially halts the
flow of refrigerant through the suction plenum 38 between the valve
body 74 and the suction cutoff wall 62 (FIG. 2B). Thus, the
configuration and arrangement of the valve body 74 and suction
cutoff wall 62 do not allow for the flow of refrigerant to the
lower stage cylinder 24L when the suction cutoff valve assembly 14
is in the fully unloaded position (FIG. 2B).
[0047] Although specifically described for the embodiments of the
suction cutoff unloader valve assembly 14 and the compressors 10M
and 10S illustrated, the manner of rapid cycling and/or alternating
the cycling of the valves described herein is equally applicable to
any compressor that utilizes valves designed to block and unblock
one or more cylinders to alter the flow of refrigerant through the
compressor. Additionally, the size of the cylinders may differ in
other embodiments of the compressor. This invention applies to
compressors operating with different types of refrigerant that can
be used to heat, cool, and provide humidity control to a
conditioned space. Some of the refrigerant types include, but not
limited to R410A, R134a, R404A, CO2, and R22.
[0048] While the invention has been described with reference to an
exemplary embodiment(s), 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(s) disclosed, but that the invention will
include all embodiments falling within the scope of the appended
claims.
* * * * *