U.S. patent application number 11/077337 was filed with the patent office on 2006-09-14 for strategic modular refrigeration system with linear compressors.
This patent application is currently assigned to Hussmann Corporation. Invention is credited to Doron Shapiro, Norman E. Street.
Application Number | 20060201175 11/077337 |
Document ID | / |
Family ID | 36540138 |
Filed Date | 2006-09-14 |
United States Patent
Application |
20060201175 |
Kind Code |
A1 |
Shapiro; Doron ; et
al. |
September 14, 2006 |
Strategic modular refrigeration system with linear compressors
Abstract
A modular commercial refrigeration unit constructed and arranged
for placement in strategic proximity to a plurality of associated
product cooling zones within a shopping area includes a
refrigeration rack proximate to a shopping area and configured to
accommodate maximum refrigeration loads of the associated product
cooling zones. The refrigeration rack has an optimum footprint. The
refrigeration rack is constructed to support components of a closed
refrigeration circuit including associated high side and low side
refrigerant delivery and suction means extending from the rack and
being operatively connected to a plurality of evaporators for
cooling the associated product cooling zones. The modular
refrigeration unit also includes a linear compressor and a cooling
source remote from the refrigeration unit that provides a cooling
relationship with a condenser for providing optimum condensing and
efficiency of the evaporators in cooling the associated product
cooling zones.
Inventors: |
Shapiro; Doron; (St. Louis,
MO) ; Street; Norman E.; (O'Fallon, MO) |
Correspondence
Address: |
MICHAEL BEST & FRIEDRICH, LLP
100 E WISCONSIN AVENUE
MILWAUKEE
WI
53202
US
|
Assignee: |
Hussmann Corporation
Bridgeton
MO
|
Family ID: |
36540138 |
Appl. No.: |
11/077337 |
Filed: |
March 10, 2005 |
Current U.S.
Class: |
62/246 ;
62/228.1 |
Current CPC
Class: |
F25B 2400/22 20130101;
F25B 1/02 20130101; A47F 3/0482 20130101; F25B 5/02 20130101; F25B
2600/02 20130101; F25B 2400/073 20130101; F25B 2400/075
20130101 |
Class at
Publication: |
062/246 ;
062/228.1 |
International
Class: |
F25B 9/00 20060101
F25B009/00; A47F 3/04 20060101 A47F003/04; F25B 1/00 20060101
F25B001/00; F25B 49/00 20060101 F25B049/00 |
Claims
1. A modular commercial refrigeration unit constructed and arranged
for placement in strategic proximity to a plurality of associated
product cooling zones within a shopping area, the modular
refrigeration unit comprising: a refrigeration rack proximate to a
shopping area and configured to accommodate maximum refrigeration
loads of the associated product cooling zones and having an optimum
footprint, wherein the refrigeration rack is constructed to support
components of a closed refrigeration circuit including associated
high side and low side refrigerant delivery and suction means
extending from the rack and being operatively connected to a
plurality of evaporators for cooling the associated product cooling
zones; a linear compressor; and a cooling source remote from the
refrigeration unit provides a cooling relationship with a condenser
for providing optimum condensing and efficiency of the evaporators
in cooling the associated product cooling zones.
2. The modular refrigeration unit of claim 1 wherein the closed
refrigeration circuit includes a plurality of linear
compressors.
3. The modular refrigeration unit of claim 2 wherein the linear
compressors are connected in parallel.
4. The modular refrigeration unit of claim 1 wherein the linear
compressor provides a variable refrigeration capacity balanced to
the refrigeration loads imposed by the associated product cooling
zones.
5. The modular refrigeration unit of claim 4 wherein the variable
refrigeration capacity is in the range of about 30% and 100%.
6. The modular refrigeration unit of claim 1 wherein the linear
compressor comprises a free-piston linear compressor including
dual-opposing pistons.
7. The modular refrigeration unit of claim 1, and further
comprising a controller to control the operation of the linear
compressor wherein the controller comprises a sensor configured to
sense a parameter representative of an operating condition
associated with the modular refrigeration unit, and wherein the
controller is operable to control the linear compressor based at
least in part on the sensed parameter.
8. The modular refrigeration unit of claim 7 wherein the linear
compressor comprises a free-piston linear compressor comprising
dual-opposing pistons, and wherein the controller is operable to
control the linear compressor by being further operable to control
the stroke of the pistons for varying the effective displaced
volume of refrigerant based at least in part on the sensed
parameter.
9. The modular refrigeration unit of claim 1 wherein the linear
compressor is located remote from the shopping area.
10. The modular refrigeration unit of claim 1 wherein the linear
compressor is mounted on the refrigeration rack.
11. The modular refrigeration unit of claim 1, and further
comprising a condenser connected between the linear compressor and
receiver means of the refrigeration circuit.
12. The modular refrigeration unit of claim 11 wherein the
condenser is mounted on the refrigeration rack.
13. The modular refrigeration unit of claim 11 wherein the
condenser is air cooled.
14. The modular refrigeration unit of claim 1 wherein the cooling
source provides a heat exchange relationship with the condenser for
providing optimum condensing and efficiency of the evaporators in
cooling the associated product cooling zones.
15. A modular refrigeration system comprising: at least two
refrigerated fixtures having first closely adjacent locations in a
shopping area; at least one evaporator coil for cooling the
refrigerated fixtures to maintain products therein within a
predetermined temperature range; a linear compressor having a
second location in close proximity to the refrigerated fixtures; a
condenser connected together with the linear compressor and the
evaporator coils to form a closed loop refrigeration circuit; a
heat exchange device located remote from the shopping area for
transferring heat to an exterior atmosphere; and a closed heat
transfer loop extending between the closed loop refrigeration
circuit and the remote environment and interconnecting the heat
exchange device and the condenser in continuous communication to
transfer heat from the condenser to the heat exchange device.
16. The refrigeration system of claim 15 wherein the second
location is in the shopping area closely adjacent to the
refrigerated fixtures.
17. The refrigeration system of claim 15 wherein the second
location is remote from the shopping area.
18. The refrigeration system of claim 15 wherein the closed loop
refrigeration circuit includes a plurality of linear
compressors.
19. The refrigeration system of claim 18 wherein the linear
compressors are connected in parallel.
20. The refrigeration system of claim 15 wherein the linear
compressor provides a variable refrigeration capacity balanced to
the refrigeration loads imposed by the associated refrigerated
fixtures.
21. The refrigeration system of claim 20 wherein the variable
refrigeration capacity is in the range of about 30% and 100%.
22. The refrigeration system of claim 20 wherein the linear
compressor comprises a free-piston linear compressor including
dual-opposing pistons.
23. The refrigeration system of claim 22 wherein the variable
refrigeration capacity is controlled by varying stroke of the
pistons.
24. The refrigeration system of claim 15, and further comprising a
controller coupled to the linear compressor, the controller
comprising a sensor configured to sense a parameter representative
of an operating condition associated with the refrigerated
fixtures, and wherein the controller is operable to control the
linear compressor based at least in part on the sensed
parameter.
25. A commercial refrigeration network comprising: a first modular
refrigeration system unit in close strategic proximity to a first
refrigerated product zone, the first modular refrigeration system
unit including a first refrigeration rack comprising first closed
refrigeration circuit components including a linear compressor,
high side receiver means and associated high side and low side
refrigerant delivery, and suction means operatively connected to a
first evaporator for cooling the first refrigerated zone, and the
first modular refrigeration system unit also including a first
condenser connected between the linear compressor and receiver
means of the first closed refrigeration circuit; at least one other
modular refrigeration system unit in close strategic proximity to
an associated other refrigerated product zone, and including an
other refrigeration rack comprising other closed refrigeration
circuit components including a linear compressor, high side
receiver means and associated high side and low side refrigerant
delivery, and suction means operatively connected to an other
evaporator for cooling the other refrigerated zone, and the other
modular refrigeration system unit also including an other condenser
connected between the linear compressor and receiver means of the
other closed refrigeration circuit; and a cooling source provides a
cooling relationship with the first and other condensers for the
respective first and other refrigeration system units.
26. The refrigeration network of claim 25 wherein the first and
other refrigerated product zones are located within a shopping area
at spaced locations therein, and the dedicated first and other
refrigeration racks are closely associated with the respective
product zones adjacent to their respective locations.
27. The refrigeration network of claim 25 wherein the refrigerated
product zones comprise a plurality of merchandisers located in the
shopping arena, the plurality of merchandisers comprising: first
merchandisers incorporating the first evaporator and associated
first refrigerant control means and first refrigeration sensing
means; and other merchandisers incorporating the other evaporator
and associated other refrigerant control means and other
refrigeration sensing means.
28. The refrigeration network of claim 25 wherein at least one of
the modular refrigeration system units includes a plurality of
linear compressors.
29. The refrigeration network of claim 28 wherein the linear
compressors are connected in parallel.
30. The refrigeration network of claim 25 wherein the linear
compressors provide a variable refrigeration capacity balanced to
the refrigeration loads imposed by the associated refrigerated
zones.
31. The refrigeration network of claim 30 wherein the variable
refrigeration capacity is in the range of about 30% and 100%.
32. The refrigeration network of claim 25 wherein each modular
refrigeration system unit further comprises a controller coupled to
the linear compressor, the controller comprising a sensor
configured to sense a parameter representative of an operating
condition associated with the modular refrigeration unit, and
wherein the controller is operable to control the linear compressor
based at least in part on the sensed parameter.
33. The refrigeration network of claim 32 wherein each linear
compressor comprises a piston, and wherein the controller is
operable to control the linear compressor by being further operable
to control the stroke of the piston based at least in part on the
sensed parameter.
34. The refrigeration network of claim 32 wherein each linear
compressor comprises a free-piston linear compressor comprising
dual-opposing pistons, and wherein the controller is operable to
control the linear compressor by being further operable to control
the stroke of the pistons for varying the effective displaced
volume of refrigerant based at least in part on the sensed
parameter.
35. The refrigeration network of claim 25 wherein the cooling
source comprises a plurality of cooling sources, each cooling
source mounted to a respective one of the first and other
condensers.
36. The refrigeration network of claim 25 wherein the cooling
source comprises a coolant circulating system having a plurality of
heat exchanger circuits in heat exchange relationship with the
respective first and other condensers for the respective first and
other refrigeration system units, the coolant circulating system
having at least one continuous cooling source for coolant in the
circulating system.
37. A commercial refrigeration network comprising: a first
refrigeration merchandiser comprising at least one first surface at
least partially defining a first environmental space adapted to
accommodate a commodity, first closed refrigeration circuit
components including a free-piston linear compressor, a condenser,
an expansion device, and an evaporator in fluid communication
wherein the evaporator is in thermal communication with the
environmental space to influence the temperature of the
environmental space, and a first frame supporting the at least one
first surface, the linear compressor and the evaporator; at least
one other refrigeration merchandiser comprising at least one other
surface at least partially defining an other environmental space
adapted to accommodate a commodity, other closed refrigeration
circuit components including a free-piston linear compressor, a
condenser, an expansion device, and an evaporator in fluid
communication wherein the evaporator is in thermal communication
with the environmental space to influence the temperature of the
environmental space, and an other frame supporting the at least one
other surface, the linear compressor and the evaporator; and a
cooling source provides a cooling relationship with the first and
other condensers for the respective first and other refrigeration
system units.
38. The refrigeration network of claim 37 wherein the first frame
also supports the condenser and the expansion device and the other
frame also supports the condenser and the expansion device.
39. The refrigeration network of claim 37 wherein at least one of
the refrigeration merchandisers includes a plurality of linear
compressors.
40. The refrigeration network of claim 39 wherein the linear
compressors are connected in parallel.
41. The refrigeration network of claim 37 wherein the linear
compressor provides a variable refrigeration capacity balanced to
refrigeration loads imposed by the refrigeration merchandiser.
42. The refrigeration network of claim 41 wherein the variable
refrigeration capacity is in the range of about 30% to 100%.
43. The refrigeration network of claim 41 wherein the linear
compressor comprises dual-opposing pistons.
44. The refrigeration network of claim 43 wherein the variable
refrigeration capacity is controlled by varying stroke of the
pistons.
45. The refrigeration network of claim 37 wherein the cooling
source comprises a plurality of cooling sources, each cooling
source mounted to a respective one of the first and other
condensers wherein the first and other condensers are air
cooled.
46. The refrigeration network of claim 37 wherein the cooling
source comprises a coolant circulating system having a fluid input
line and a fluid output line in fluid communication with the
respective first and other condensers for the respective first and
other refrigeration merchandisers, the coolant circulating system
having at least one continuous cooling source for coolant in the
circulating system.
Description
BACKGROUND
[0001] The present invention relates to commercial refrigeration
systems, and in particular, commercial refrigeration systems having
at least one linear compressor.
[0002] Commercial refrigeration systems have traditionally been
accomplished via centralized parallel compressor systems with long
liquid and suction branches piped to and from the evaporators in
the refrigerated display cases. As an alternative, centralized
parallel rack refrigeration systems have been developed for cooling
a plurality of fixtures in multiple cooling zones within a shopping
area. Another alternative is a self-contained, refrigeration
display merchandiser including multiple horizontal scroll
compressors.
[0003] A disadvantage to all these systems is the use of scroll
compressors within the commercial refrigeration systems. Scroll
compressors generate too much acoustic noise for the shopping area
of a store and do not allow for variable capacity control of the
refrigeration system. Because of the lack of variable capacity
control, the compressor may perform unnecessary cycling, which may
be detrimental to the stored commodity (e.g., sensitive food
products) refrigerated by the merchandisers or refrigerated display
cases. Further, scroll compressors use oil for operation, which
results in inefficient performance due to oil film on evaporator
and condenser surfaces, requires the use of expensive oil
management components, and increases the installation cost of the
refrigeration system.
[0004] It would be beneficial to have another alternative to the
above systems and units utilizing scroll compressors.
SUMMARY
[0005] In one embodiment, the invention provides a modular
commercial refrigeration unit constructed and arranged for
placement in strategic proximity to a plurality of associated
product cooling zones within a shopping area. The modular
refrigeration unit includes a refrigeration rack proximate to a
shopping area and configured to accommodate maximum refrigeration
loads of the associated product cooling zones. The refrigeration
rack has an optimum footprint. The refrigeration rack is
constructed to support components of a closed refrigeration circuit
including associated high side and low side refrigerant delivery
and suction means extending from the rack and being operatively
connected to a plurality of evaporators for cooling the associated
product cooling zones. The modular refrigeration unit also includes
a linear compressor and a cooling source remote from the
refrigeration unit that provides a cooling relationship with a
condenser for providing optimum condensing and efficiency of the
evaporators in cooling the associated product cooling zones.
[0006] In another embodiment, the invention provides a modular
refrigeration system including at least two refrigerated fixtures
having first closely adjacent locations in a shopping area, at
least one evaporator coil for cooling the refrigerated fixtures to
maintain products therein within a predetermined temperature range,
a linear compressor having a second location in close proximity to
the refrigerated fixtures, and a condenser connected together with
the linear compressor and the evaporator coils to form a closed
loop refrigeration circuit. The modular refrigeration system also
includes a heat exchange device located remote from the shopping
area for transferring heat to an exterior atmosphere, and a closed
heat transfer loop extending between the closed loop refrigeration
circuit and the remote environment and interconnecting the heat
exchange device and the condenser in continuous communication to
transfer heat from the condenser to the heat exchange device.
[0007] In still another embodiment, the invention provides a
commercial refrigeration network including a first modular
refrigeration system unit in close strategic proximity to a first
refrigerated product zone. The first modular refrigeration system
unit includes a first refrigeration rack having first closed
refrigeration circuit components including a linear compressor,
high side receiver means and associated high side and low side
refrigerant delivery, and suction means operatively connected to a
first evaporator for cooling the first refrigerated zone. The first
modular refrigeration system unit also includes a first condenser
connected between the linear compressor and receiver means of the
first closed refrigeration circuit. The commercial refrigeration
network also includes at least one other modular refrigeration
system unit in close strategic proximity to an associated other
refrigerated product zone. The at least one other modular
refrigeration system includes an other refrigeration rack having
other closed refrigeration circuit components including a linear
compressor, high side receiver means and associated high side and
low side refrigerant delivery, and suction means operatively
connected to an other evaporator for cooling the other refrigerated
zone. The other modular refrigeration system unit also includes an
other condenser connected between the linear compressor and
receiver means of the other closed refrigeration circuit. Further,
the commercial refrigeration network also includes a cooling source
remote from the refrigeration unit that provides a cooling
relationship with the first and other condensers for the respective
first and other refrigeration system units.
[0008] In a further embodiment, the invention provides a commercial
refrigeration network including a first refrigeration merchandiser,
at least one other refrigeration merchandiser, and a cooling
source. The first refrigeration merchandiser includes at least one
first surface at least partially defining a first environmental
space adapted to accommodate a commodity, first closed
refrigeration circuit components, and a first frame. The first
closed refrigeration circuit components include a free-piston
linear compressor, a condenser, an expansion device, and an
evaporator in fluid communication wherein the evaporator is in
thermal communication with the environmental space to influence the
temperature of the environmental space. The first frame supports
the at least one first surface, the linear compressor and the
evaporator. The at least one other refrigeration merchandiser
includes at least one other surface at least partially defining an
other environmental space adapted to accommodate a commodity, other
closed refrigeration circuit components, and an other frame. The
other closed refrigeration circuit components include a free-piston
linear compressor, a condenser, an expansion device, and an
evaporator in fluid communication wherein the evaporator is in
thermal communication with the environmental space to influence the
temperature of the environmental space. The other frame supports
the at least one other surface, the linear compressor and the
evaporator. The cooling source remote from the refrigeration unit
provides a cooling relationship with the first and other condensers
for the respective first and other refrigeration system units.
[0009] Other aspects and advantages of the invention will become
apparent by consideration of the detailed description, claims and
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a block diagram illustrating a modular commercial
refrigeration network embodying the invention.
[0011] FIG. 2 is a schematic flow diagram of a modular
refrigeration system unit and coolant circulating system.
[0012] FIG. 3 is a schematic flow diagram of a refrigeration system
unit and coolant circulating system located remotely from the
respective refrigeration loads.
[0013] FIG. 4 is a schematic flow diagram of a modular
refrigeration system unit with an air cooled condenser.
[0014] FIG. 5 is a representative supermarket floor plan
illustrating the strategic placement of dedicated modular
refrigeration system units relative to the respective refrigeration
loads and positioned remotely of the respective refrigeration
loads.
[0015] FIG. 6 is a sectional view of a dual opposing, free-piston
linear compressor used in a refrigeration unit, which shows the
compressor at an intake stroke.
[0016] FIG. 7 is a sectional view of a dual opposing, free-piston
linear compressor used in a refrigeration unit, which shows the
compressor at neutral.
[0017] FIG. 8 is a sectional view of a dual opposing, free-piston
linear compressor used in a refrigeration unit, which shows the
compressor at a compression stroke.
[0018] FIG. 9 is an enlarged supermarket floor plan illustrating a
department with a dedicated modular refrigeration unit having
multiple linear compressors.
[0019] FIG. 9A is a top plan view of the refrigeration unit of FIG.
9 illustrating a heat exchanger network with a cooling liquid
source.
[0020] FIG. 10 is an enlarged supermarket floor plan illustrating a
department with merchandisers and a dedicated refrigeration unit
having multiple linear compressors located remotely from the
merchandisers.
[0021] FIG. 11 is a diagrammatic perspective view showing an open
front refrigerated merchandiser lineup and associated vertical
modular refrigeration unit.
[0022] FIG. 12 is another diagrammatic perspective view showing a
lineup of reach-in merchandisers strategically incorporating a
vertical modular refrigeration unit.
[0023] FIG. 13 is a plan view of a lineup of wide island cases
showing a linear compressor arrangement in the associated modular
refrigeration unit.
[0024] FIG. 14 is a plan view of a lineup of wide island cases with
an associated refrigeration unit including multiple linear
compressors located remotely of the wide island cases.
[0025] FIG. 15 is a diagrammatic side elevational view illustrating
a modular refrigeration rack for a refrigeration unit with multiple
linear compressors.
[0026] FIG. 15A is a diagrammatic plan view of the modular
refrigeration rack of FIG. 15.
[0027] FIG. 16 is a perspective view of two refrigeration
merchandisers and further showing elements of the refrigeration
cycle of the merchandisers.
[0028] Before any embodiments of the invention are explained in
detail, it is to be understood that the invention is not limited in
its application to the details of construction and the arrangement
of components set forth in the following description or illustrated
in the following drawings. The invention is capable of other
embodiments and of being practiced or of being carried out in
various ways. Also, it is to be understood that the phraseology and
terminology used herein is for the purpose of description and
should not be regarded as limiting. The use of "including,"
"comprising," or "having" and variations thereof herein is meant to
encompass the items listed thereafter and equivalents thereof as
well as additional items. Unless specified or limited otherwise,
the terms "mounted," "connected," "supported," and "coupled" and
variations thereof are used broadly and encompass both direct and
indirect mountings, connections, supports, and couplings. Further,
"connected" and "coupled" are not restricted to physical or
mechanical connections or couplings.
[0029] For purposes of disclosure, the term "high side" is used
herein in a conventional refrigeration sense to mean a portion of a
system from the compressor discharge to the evaporator expansion
valves, and the term "low side" means the portion of the system
from the expansion valves to the compressor suction. Also, "low
temperature" as used herein shall have reference to evaporator
temperatures in the range of about -35.degree. F. to about
-5.degree. F., or the associated product temperatures in the range
of about -20.degree. F. to about 0.degree. F. Further, "normal
temperature" as used herein means evaporator temperatures in the
range of about 15.degree. F. to about 40.degree. F., or the
associated non-frozen product temperatures in the range of about
25.degree. F. to about 50.degree. F. "Medium temperature" is also
used interchangeably for "normal temperature" in the refrigeration
industry.
DETAILED DESCRIPTION
[0030] FIG. 1 illustrates an inventive commercial refrigeration
network 10 diagrammatically. The commercial refrigeration network
10 includes a plurality of modular refrigeration system units 14
constructed and arranged for placement in strategic proximity to
corresponding product cooling zones within a commercial space 18
(e.g., a foodstore, supermarket, etc.). The location of the
refrigeration units 14 may be within or remote from a customer
shopping area 22 of the commercial space 18. In FIG. 1, two modular
refrigeration units 14A and 14B are shown within the shopping area
22, and one modular refrigeration unit 14C is shown outside of the
shopping area 22. Each refrigeration system unit 14, or
merchandiser, includes at least one linear compressor 22 (shown in
FIG. 2) and is sized to efficiently maintain its associated
discrete cooling zone at optimum refrigeration temperatures. Each
of the cooling zones comprises one or more of the store coolers,
freezers, preparation rooms or display merchandisers. A cooling
zone is typically an area, department, or lineup of merchandising
fixtures operating at substantially the same temperature.
[0031] The refrigeration network 10 includes a coolant circulating
system 30 constructed and arranged to circulate a cooling fluid or
coolant from a remote source 34 to a respective refrigeration unit
condenser/heat exchanger 38. The circulation of a controlled
coolant in a heat exchange relationship with the unit condensers
provides optimum condensing and refrigeration efficiency of the
evaporators in cooling their respective product zones. The coolant
system 30 derives a cooling liquid, such as chemically treated
water or a glycol solution, from one or more sources 34 and
circulates the cooling liquid by at least one pump 42 through a
distribution arrangement. In the illustrated embodiment, the
distribution arrangement includes a distribution manifold 46 and
branch coolant delivery lines or conduits 50 to the condenser/heat
exchanger 34 of each modular unit 14. For example, and as shown in
FIGS. 2, 3, and 16, a secondary fluid (e.g., a liquid) provided by
the fluid-input line 50, or conduits, cools the condenser 38. At
least two alternate cooling sources 34A, 34B are illustrated as an
arrangement to assure a back-up condenser cooling system. Branch
return conduits 54, or a fluid-output, and a return manifold 58
carry away the coolant fluid with the exchanged heat of rejection
from the respective refrigeration unit condensers 38 for
dissipation externally of the shopping area 22.
[0032] The coolant sources 34A, 34B, 34C, 34D may be a single fluid
cooling apparatus, such as a closed or open loop roof top cooling
tower, a ground source water supply, a dedicated normal temperature
refrigeration system, a chiller system or recirculating water
source, or a combination of such alternate fluid cooling sources to
assure a continuous supply of coolant at a substantially constant
temperature, as will be discussed below. In an embodiment including
multiple modular refrigeration units 14, the refrigeration units 14
derive their respective condenser cooling from a common liquid
cooling source 34 remote from the modular refrigeration units 14 in
the shopping area 22. In one embodiment, the heat exchanger is of
the plate-to-plate type for optimal heat transfer of the heat of
rejection transferred from the product zone through the unit
condensers 38 to the coolant, which then carries the cumulative
heat load in a heated coolant return mode for dissipation
externally of the shopping area 22. It will be readily apparent to
those skilled in the art that the heat of rejection and the heat of
compression from the linear compressors may be utilized for
seasonal heating of the supermarket.
[0033] As will be discussed further below, the fluid can also be
used to cool other components of the refrigeration unit 14. In
other embodiments, the merchandiser 14 includes a fan if the
condenser 38 is air-cooled.
[0034] The modular nature of the refrigeration units 14 utilizes
three basic variable forms of the refrigeration unit 14: a vertical
compressor configuration, such as 14C (shown in FIGS. 1, 11, 12); a
horizontal compressor configuration, such as 14B (shown in FIGS. 1,
2, 9, 13, 15); and a combination or mixed horizontal and vertical
compressor configuration, such as 14A (shown in FIGS. 1, 12,
16).
[0035] During a refrigeration cycle, the linear compressor 26
compresses a refrigerant, resulting in the refrigerant increasing
in temperature and pressure. The compressed refrigerant is sent out
of the linear compressor 26 as a high-temperature, high-pressure
heated gas. The refrigerant travels to a condenser 38 (shown in
FIG. 2). The condenser 38 changes the refrigerant from a
high-temperature gas to a warm-temperature gas/liquid, which
maintain the associated discrete cooling zones at an optimum
refrigeration temperature. As discussed above, air and/or a liquid
are used to help the condenser 38 with this transformation.
[0036] FIG. 2 is a schematic flow diagram of a modular
refrigeration unit 14 and coolant circulating system 30. In FIG. 2,
each of the modular refrigeration units 14 includes a refrigeration
rack 62 constructed and arranged to mount and support the operative
components of a closed refrigeration circuit 66. The closed
refrigeration circuit 66 is dedicated to refrigeration load
requirements of its associated discrete product cooling zone 68. In
the illustrated embodiment, the refrigeration rack 62 includes four
linear compressors 26 connected in parallel. In further
embodiments, at least one and up to ten linear compressors 26 may
be included in the refrigeration unit 14 and supported by the
refrigeration rack 62. The linear compressors 26 are connected by a
discharge header 70 to a diverting valve 74. The diverting valve 74
selectively connects the discharge header 70 to a heat recovery
means, such as a heat reclaim coil 78 or a hot water exchanger (not
shown), or directly to the system condenser 38 located on the
refrigeration rack 62. In the illustrated embodiment, a liquid
receiver 82 is connected to the condenser 38 to receive the
condensate outflow from the condenser 38.
[0037] The high side of the refrigeration circuit 66 is connected
by liquid lines 86 to evaporative expansion valves 90 at each
evaporator 94 associated with a discrete product cooling zone 68 to
be cooled. On the low side, the refrigerant expands and vaporizes
in the merchandiser evaporators 94 removing heat from the product
zone 68 to maintain the preselected desired cooling. The outlets of
the evaporators 68 connect to a common suction header or manifold
98. The suction manifold 98 connects to the suction side of the
compressors 26 to complete the refrigeration circuit 66. It will be
readily apparent to those skilled in the art that individual
modular refrigeration units 14 may generally include other system
components, such as defrost system means, system performance
sensing and operating control panel, microprocessor apparatus,
alarm systems and the like.
[0038] FIG. 2 illustrates a unit heat reclaim coil 78 as part of
the closed refrigeration circuit 66 of the refrigeration unit 14.
Such a heat reclaim coil 78 is generally housed in a conventional
store air handler (not shown) for seasonal air conditioning and
environmental heating of the store, but may be located remotely as
a water heating unit (not shown). Due to the modularity of the
refrigeration units 14 and their proximate location to their
respective cooled product zones, it is contemplated that unit heat
reclaim coils 78 may be strategically located under selected
merchandisers or the like for environmental shopping arena heating.
It will be readily apparent that a heat reclaim coil 78 is
typically designed to function as a pre-condenser that removes heat
from the compressed vaporous refrigerant on the high side upstream
of the system condenser. The heat reclaim coil 78 does not reduce
the refrigerant vapor to its saturated condensing temperature,
because this is the final function of the condenser 38 at the unit
heat exchanger.
[0039] The use of linear compressors 26 in the refrigeration units
14 provides for oil-free operation of the refrigeration system and
gives performance and cost advantages over existing systems. Linear
compressors 26 used in the refrigeration units 14 eliminate the
need for oil management components (such as oil separators, oil
controls, oil safety devices, etc) within the refrigeration system.
Heat transfer within the refrigeration system is improved due to
the absence of an oil film on evaporator and condenser surfaces.
Further, installation costs are lower due to the elimination of the
need for suction traps. The use of linear compressors 26 in the
refrigeration units 14 also provides for continuously variable
capacity of the refrigeration loads from about 30% to 100%
(discussed below with respect to FIGS. 6-8), as compared to
existing systems utilizing scroll compressors.
[0040] In the embodiment illustrated in FIG. 2, the modular
refrigeration unit 14 is strategically placed in the commercial
space 18 in close proximity to the dedicated cooling zone 68 of an
associated merchandiser department or case lineup. In another
embodiment illustrated in FIG. 3, the components of the closed
refrigeration circuit 66 are located remotely of the dedicated
cooling zone 68, such as in a service area 102 (shown in FIG. 5) of
the commercial space 18. In some embodiments, the closed
refrigeration circuit components, including the linear compressors
26, are not arranged on a refrigeration rack and instead are
positioned separately to form the closed refrigeration circuit
66.
[0041] In another embodiment illustrated in FIG. 4, the modular
refrigeration unit 14 includes an air cooled condenser 38 located
remotely of the refrigeration rack 62, for example on a roof of the
commercial space 18. A fan 100 mounted to or within the condenser
38 provides cooling to the refrigerant passing through the
condenser. An air cooled condenser is an alternative cooling means
from the coolant circulating system 30 shown in FIGS. 2 and 3. In
further embodiments, the air cooled condenser 38 may be located
remotely from the commercial space 18 or in the service area 102 of
the commercial space 38.
[0042] FIG. 5 is a representative supermarket floor plan
illustrating the strategic placement of dedicated modular
refrigeration system units 14 relative to the respective
refrigeration loads, as well as refrigeration units 14 located
remotely from the respective refrigeration loads in a service area
102 of the commercial space 18. In the embodiment illustrated in
FIG. 5, refrigeration unit 14A is a medium temperature system
servicing the produce department merchandisers 68A operating at
temperatures in the range of about 45.degree. F. to about
50.degree. F. (see also FIG. 9). Refrigeration unit 14B is a low
temperature system dedicated to maintain ice cream product
temperatures of about -20.degree. F. in twin island "coffin" type
merchandisers 68B in the shopping area 22. Although the
refrigeration unit 14B is located in the service area 102, in
further embodiments it may be located proximate the merchandisers
68B (see also FIG. 13). Refrigeration unit 14C is a low temperature
system for a dual back-to-back lineup of frozen food reach-in
merchandisers 68C within the shopping area 22 (see also FIG. 11).
Refrigeration unit 14D is a low temperature system dedicated to
maintain frozen meat products in a meat freezer (cooling zone 68D)
located in the service area 102 outside of the shopping area 22.
Refrigeration unit 14E is a medium temperature system located in
the service area 102, but immediately adjacent to its discrete
service load of multi-deck meat merchandisers 68E in the shopping
area 22. Refrigeration unit 14F is a medium temperature system for
a lineup of non-frozen reach-in product fixtures 68F in the
shopping area 22. Refrigeration unit 14G is a medium temperature
system also located in the service area 102, but constructed and
arranged to service both a deli walk-in cooler 68G1 in the service
area 102 and a deli merchandiser lineup 68G2 in the shopping area
22. Refrigeration unit 14H is a medium temperature system for
servicing a line of multi-deck produce merchandisers 68H. In the
illustrated embodiment, the refrigeration unit 14H is located in
the service area 102, however, in another embodiment the
refrigeration unit 14H is located proximate the merchandisers 68H
(see also FIG. 11). Refrigeration unit 14I is a low temperature
system dedicated to an ice cream walk-in freezer 68I in the service
area 102. Finally, refrigeration unit 14J is a medium temperature
system associated with a dairy department lineup of multi-deck
merchandisers 68J. In the illustrated embodiment, refrigeration
unit 14J is located in the service area 102, however, in another
embodiment the refrigeration unit 14J is located proximate the
merchandisers 68J.
[0043] It will be readily apparent to those skilled in the art that
a typical supermarket layout may also include a refrigerated floral
merchandiser, an in-store bakery with coolers and retarder units, a
seafood department and other non-refrigerated departments, dry
goods shelving, customer checkout area and the like. As illustrated
in FIG. 5, the conventional compressor machine room of existing
supermarkets is eliminated in favor of the modular refrigeration
units 14A-14J strategically located in and around the shopping area
22 and in the service area 102 of the commercial space 18. The
refrigeration units 14 are specifically dedicated to discrete
refrigeration loads. Those refrigeration units 14 located in close
proximity to an associated group of storage or display
merchandising zones operate at the same temperature and form the
discrete load. In further embodiments, the service area 102 of the
commercial space 18 may have a separate compressor machine room
(not shown) for housing the linear compressors 26. However, the use
of linear compressors 26 results in virtually no vibration,
therefore, the need for a separate space to acoustically isolate
the compressors is not necessary.
[0044] As described herein, the refrigeration systems,
refrigeration units, and merchandisers include at least one linear
compressor 26. It is envisioned that, in some embodiments, the
linear compressor is a free-piston linear compressor, and in at
least on envisioned embodiment, the free-piston linear compressor
is a dual-opposing, free-piston linear compressor. A dual-opposing,
free-piston linear compressor is obtainable from Sunpower, Inc.
(Athens, Ohio, USA). Another example of a dual-opposing,
free-piston linear compressor is disclosed in U.S. Pat. No.
6,641,377, issued Nov. 4, 2003, the content of which is
incorporated herein by reference.
[0045] The free-piston linear compressor has some basic differences
over conventional rotary compressors. The free-piston device is
driven by a linear motor in a resonant fashion (like a spring-mass
damper) as opposed to being driven by a rotary motor and mechanical
linkage. One advantage with the linear motor is that the side loads
are small, which greatly reduces friction and allows use of simple
gas bearings or low-viscosity oil bearings. In addition, since
friction has been greatly reduced, the mechanical efficiency of the
device is greater, internal heat generation is lower, and acoustic
noise is reduced. Additionally, inherent variable piston stroke
allows for efficient capacity modulation over a wide range. For
example, linear compressors have continuously variable capacity
from about 30% to 100% by adjusting piston stroke. In constructions
having dual-opposing pistons, the pistons vibrate against each
other (i.e., provide a mirrored system) to virtually cancel all
vibration. This reduces the acoustic noise of the linear compressor
even further than a single piston linear compressor.
[0046] FIGS. 6, 7, and 8 show three sectional views of a
dual-opposing linear compressor 110 capable of being used with the
modular refrigeration systems, refrigeration units and
merchandisers described above. FIG. 6 shows the compressor 110 at
an intake stroke, FIG. 7 shows the compressor 110 at neutral, and
FIG. 8 shows the compressor 110 at a compression stroke. As shown
in FIGS. 6-8, the dual-opposing linear compressor 110 includes a
housing 114 supporting a main body block 118. Inner and outer
laminations 122 and 126 are secured to the main body block 118 and
coils 130 are wound on the outer laminations 126, thereby forming
stators. The stators, when energized, interact with magnet rings
134 mounted on outer cylinders 138. The outer cylinders 138 are
fastened to pistons 142, which are secured to springs 146. The
interaction between the magnet rings 134 and the energized stators
results in the outer cylinders 138 moving the pistons 142 linearly
along an axis of reciprocation 150.
[0047] When the pistons 142 are at the intake stroke, refrigerant
is allowed to flow from a suction port 154 through channels 158
into a compression space 162 (best shown in FIG. 6). When moving
from the intake stroke to the compression stroke, valves 166 (best
shown in FIG. 7) close the channels, and the refrigerant is
compressed out through discharge valve 170 and discharge port 174
(best shown in FIG. 8). The linear motor allows for variable
compression (e.g., from approximately 30% to 100%) by the pistons
142, and therefore, the linear compressor 110 provides variable
capacity control. In other words, the linear motors can cause the
pistons 142 to move a small stroke for a first volume, or to move a
larger stroke for a second, larger volume. The linear compressors
110 provide a variable refrigeration capacity (e.g., by varying
piston stroke) balanced to the refrigeration loads imposed by the
associated product cooling zones 68. Accordingly, the refrigeration
units 14 allow for variable loads, decrease compressor cycling, and
reduce temperature swings.
[0048] In some embodiments, the linear compressor 110 includes a
jacket 178 (shown in phantom) enclosing at least a portion of the
housing 114. The jacket 178 includes a fluid-input port 182 and a
fluid-output portion 186, and provides a plenum 190 containing a
cooling fluid, thereby providing a fluid-cooled compressor. Other
arrangements for cooling the compressor with a fluid are
possible.
[0049] An example of a compressor controller for use with the
dual-opposing, free-piston linear compressor shown in FIGS. 6-8 is
disclosed in U.S. Pat. No. 6,536,326, issued Mar. 25, 2003, the
content of which is incorporated herein by reference. It is also
possible for the coolant fluid to be used for cooling a controller
192 (shown in FIG. 11). Similar to the linear compressor, a jacket
having input and output ports can be used to surround a housing of
the controller.
[0050] An example of refrigeration unit 14A and its associated
refrigerated zone 68A is illustrated in FIGS. 9 and 9A. The cooling
zone illustrated is a medium temperature produce section or
department 194 of a supermarket. The illustrated cooling zone 194
includes two refrigerated produce tables 194A, one unrefrigerated
produce table 194B (used for products not requiring refrigeration),
and one or more lineups of multi-deck or gondola produce
merchandisers 194C. The refrigeration unit 14A may be concealed
under one of the refrigerated tables 194A, in the base of the
unrefrigerated produce table 194B, or in a merchandiser lineup
194C. The refrigeration unit 14A may be accessed by removing a
front panel of the merchandiser, or by constructing and arranging a
table top of the merchandiser to be hinged for vertical lifting
movement or for horizontal side movement thereon. In the
illustrated embodiment, the refrigeration rack 62 is constructed
and arranged to support four linear compressors 26 in a combination
arrangement of two pairs of horizontally disposed compressors in
side-by-side relationship. The linear compressors are connected in
parallel and may be operated individually, cyclically or variably
to keep the merchandiser temperatures constant. FIG. 9A shows that
the condenser 38 of the modular unit 14A is part of a heat
exchanger 198 containing a coolant loop having cool coolant
delivery mode 50 and a warm coolant return mode 54.
[0051] FIG. 10 is an alternate configuration of the cooling zone
194 shown in FIG. 9. FIG. 10 illustrates a refrigeration system
having refrigeration components located remotely of the associated
refrigerated zone 68A. The refrigeration components may be located
on a refrigeration rack 62 or positioned independently to form the
closed refrigeration circuit 66. Referring to FIGS. 9 and 10, a
discharge conduit 202 connects the compressor head manifold 70
(i.e., discharge header) to the unit condenser 38 on the
refrigeration rack 62. The condenser 38 connects through the system
receiver-accumulator 82 (shown in FIG. 2) to the liquid line
conduits 86 that extend in short runs from the refrigeration unit
14A beneath the floor to the evaporators 94 in the merchandisers
194. A suction conduit 206 returns the vaporized refrigerant liquid
to the compressors 26. In the illustrated embodiment, a coolant
delivery line 50 from the remote cooling liquid source 34 (shown in
FIG. 1) is piped beneath the floor or overhead to the refrigeration
rack 62 for removing the heat of rejection and compression from the
unit condenser 38 in the heat exchanger 198. Further, a coolant
return line 54 is provided to expel this heat to a location
exterior of the supermarket. In a further embodiment of the
refrigeration unit 14A shown in FIGS. 9 and 10, the condenser is
air cooled and located remotely of the refrigeration unit 14A.
[0052] Additional configurations of the linear compressors 26
accommodated by the modular refrigeration racks 62 and their
associated discrete refrigeration loads are shown in FIGS. 11-14.
In each embodiment, all of the closed refrigeration circuit
components are rack mounted except for the merchandiser 68 or other
zone evaporators 94 and associated refrigerant control and sensing
means. Examples of other equipment not mounted on the refrigeration
rack include expansion valves 90 and defrost control valves (not
shown), as well as connecting discharge and suction lines between
the evaporators and the refrigeration system racks.
[0053] In FIG. 11, the modular refrigeration unit 14 utilizes a
vertical linear compressor unit that is positioned behind a
shelving unit 210. The shelving unit 210 is arranged to cover one
side of the modular refrigeration unit 14 when positioned at the
end of a merchandiser lineup, such as the open front multi-deck
merchandisers 214 shown in FIG. 11. FIG. 12 illustrates lineups of
reach-in merchandisers, such as merchandiser 68F, in which the
modular refrigeration units and refrigeration racks are interposed
into the middle of the lineups. In FIG. 12, the refrigeration unit
14F includes a vertical stack of linear compressors 26.
[0054] FIG. 13 illustrates another configuration of a horizontal
linear compressor unit centrally located between parallel rows or
twin island coffin merchandisers 68B of the type used for ice cream
or other frozen products. The three linear compressors 26 are
arranged on a horizontal line in the modular refrigeration unit 14B
and at least one exterior side of the refrigeration rack 62 has a
removable panel 218 that can be replaced after service. In the
embodiment illustrated in FIG. 14, the refrigeration unit 14B and
the refrigeration rack 62 are positioned remotely from the parallel
rows or twin island coffin merchandisers 68B, oftentimes in a
service area 102 (shown in FIG. 5) of the commercial space 18.
[0055] The location of the modular refrigeration units 14, whether
in the shopping area 22 or in the service area 102 of the
commercial space 18, are in close proximity to the associated
refrigeration loads serviced by the respective units. Such
placement greatly reduces the amount of refrigerant needed and the
length of piping needed to carry the refrigerant to all the product
merchandisers. The placement of the refrigeration units 14 in the
shopping area 22 is commercially feasible only if the acoustic
noise from the compressors is substantially eliminated or reduced
to acceptable decibel levels. As discussed above, the use of linear
compressors in the refrigeration units reduces the acoustic noise
of the refrigeration unit and virtually cancels all vibration of
the unit, as compared to compressors used in prior art systems.
[0056] The modularity of the refrigeration racks 62 for forming
variant refrigeration unit arrangements is described with respect
to FIGS. 15 and 15A. In the illustrated embodiment, the
refrigeration rack 62, for a horizontal linear compressor unit,
includes a series of similar frame modules 220. Each frame module
220 includes a main frame having lower or first level horizontal
structural members 224 forming a rectangular base and vertical
struts 228, or stanchions, located at the corners of the base 224.
FIGS. 15 and 15A illustrate a four linear compressor unit with
three frame modules 220 joined together. The two leftward modules
also include upper or second level horizontal structural member 232
secured to the vertical stanchions 228 in spaced relation above the
lower base level 224. Each frame module 220 is provided with a
horizontally extending metal support or mounting plate 236 that is
preformed to receive and secure specific components of the closed
refrigeration system. In the illustrated embodiment, the leftward
mounting plates 236A are each constructed and arranged to mount two
linear compressors 26. It will be readily apparent that the
condenser/heat exchanger 38 and the receiver 82 are also
accommodated by the modular refrigeration rack arrangement. The
rightward unit 236B is designed to mount a control panel 240 for
operating the associated refrigeration system of the modular
refrigeration unit.
[0057] It will also be readily apparent to those skilled in the art
that the same base frame module 220, lower level base frame 224,
vertical struts 228, second level frame 232, and mounting plate 236
may be used to form a vertically arranged refrigeration rack or a
combination refrigeration rack. The embodiment shown and described
with respect to FIGS. 15 and 15A is illustrative only. The
refrigeration rack may assume other configurations, such as a
vertical linear compressor arrangement in which single linear
compressors 26 are stacked one above the other in a tier that
affords a minimum floor space footprint and excellent accessibility
for service.
[0058] The modular refrigeration unit 14 includes a single
electrical junction to the refrigeration rack that permits the
connection of all system components as well as local wiring control
over the ancillary merchandiser electrical equipment (e.g.,
lighting, fans, antiswear heaters) for wiring from the same
location. Only a single power circuit is required to extend from a
remote power source (not shown) to the unit junction box usually
associated with the control panel 240. In the illustrated
embodiment, the junction box is connected to the control panel that
contains a remotely activated contactor and circuit breaker system
for providing distributed electrical power via buss arrangement to
the electrical components in the system.
[0059] In one embodiment, each of the modular refrigeration units
is monitored and controlled by a personal computer linked to a
microprocessor within the control panel 240. The control system is
conventional, except that the linear compressors are located around
the commercial space, and are supplemented by individual control
systems (i.e., microprocessors) associated with each rack.
Interrogation of individual units to diagnose problems and override
of the general control functions for purposes of testing and repair
is accomplished at the specific refrigeration units. To reduce
duplication of components such as visual system readouts on each
control panel, it is envisioned that a hand-held monitor would be
used to plug into the microprocessor and provide a visual readout
of its settings and conditions.
[0060] The modularity of the refrigeration units 14 and the
refrigeration racks 62 reduces the time and cost of installing the
refrigeration system network and simplifies service, as compared to
conventional back room refrigeration systems. Further, since the
alternate configurations of the refrigeration units and racks are
pre-designed, less field assembly of conduit joints are required.
The flexibility in the modular refrigeration units permits the
dedicated units to be located unobtrusively within a public area of
a commercial space, such as a supermarket, in such a way as to
blend with the closely adjacent configurations of refrigerated
product storage coolers and display merchandisers having the
associated cooling zones.
[0061] FIG. 16 shows a self-contained refrigeration unit 250, or
merchandiser. The refrigeration unit 250 is shown as an open-unit
display merchandiser having a single display fixture 254. However,
other types of merchandisers (e.g., a glass-door display
merchandiser, a vending machine, a dispenser, etc.) can embody the
invention. Also, it is envisioned that the merchandiser 250 can
include more than one display fixture (e.g., is a combination
merchandiser). As used herein, the term "self-contained
refrigeration unit" means a refrigeration unit where the frame of
the unit supports the linear compressors 26, the condenser 38, the
expansion valve 90, and the evaporator 94.
[0062] With reference to FIG. 16, the merchandiser 250 includes a
frame 258 supporting the display fixture 254 and the components
providing the refrigeration cycle (discussed below). As used
herein, the term "frame" is broadly defined as something composed
of parts fitted together and united. The frame 258 includes the
housing of the unit, the one or more components of the
refrigeration cycle, and/or the display fixture. Alternatively, the
frame 254 provides the foundation for the housing, the one or more
components of the refrigeration cycle, and/or the display fixture.
The display fixture 254 comprises a cabinet, case, container or
similar receptacle adapted to accommodate a commodity. The fixture
254 includes at least one surface 262 that at least partially
defines an environmental space. For a "glass-door" display
merchandiser, at least one of the surfaces defining the
environmental space is partially defined by a translucent
material.
[0063] It should be noted that some merchandisers do not include a
display fixture, however, the refrigeration unit still includes at
least one surface at least partially defining an environmental
space. Also the refrigeration unit 250 can include multiple
environmental spaces. As used herein, the term "environmental
space" is a three-dimensional space (defined at least in part by
the at least one surface) where the environment is controlled by
the refrigeration unit. For example, the refrigeration unit 250 of
FIG. 16 consists of two environmental spaces 266 and 270, where the
temperatures of the environmental spaces are controlled by the
components of the refrigeration cycle. Other characteristics (e.g.,
humidity) of the environmental spaces 266 and 270 can be
controlled.
[0064] As shown in FIG. 16, the components forming the
refrigeration cycle comprises the linear compressor 26, the
condenser 38, the expansion device 90 (also typically referred to
as the expansion valve), and the evaporator 94, all of which are in
fluid communication. Of course, in further embodiments, the
refrigeration cycle can include other components, such as the
receiver 82 or a filter (not shown).
[0065] The refrigeration unit includes the controller 192 that
controls the refrigeration unit. The controller 192 includes one or
more temperature sensors and/or one or more pressure sensors (only
one sensor 274 is shown) coupled to the refrigeration unit. The
controller also includes a user-input device. The controller 192
receives refrigeration unit input information (i.e., signals or
data) from the sensor(s) 274, receives user input (e.g.,
temperature settings) from the user input device, processes the
inputs, and provides one or more outputs to control the
refrigeration unit (e.g., to control the compressor, control the
expansion device, control a defrost system, etc.). In further
embodiments, the controller 192 is used with other refrigeration
units or merchandisers and may be located in the control panel 240
of such units.
[0066] For the refrigeration unit shown, the controller 192
includes the compressor controller. However, the refrigeration unit
controller 192 can be separated into multiple controllers (e.g., a
controller for overall control and a compressor controller), which
is typically referred to as a distributed control system. An
example of a distributed control system is disclosed in U.S. Pat.
No. 6,647,735, issued Nov. 18, 2003, the content of which is
incorporated herein by reference.
[0067] In one embodiment, the controller 192 includes one or more
programmable devices (e.g., one or more microprocessors, one or
more microcontrollers, etc.) and a memory. The memory, which can
include multiple memory devices, includes program storage memory
and data storage memory. The one or more programmable devices
receive instructions, receive information (either directly or
indirectly) from the devices in communication with the programmable
devices, execute the instructions, process the information, and
communicate outputs to the attached devices.
[0068] The user-input device is shown in FIG. 16 as a user
interface 278. The user-input device can be as simple as a
thermostat dial. Other user-input devices include push-buttons,
switches, keypads, a touch screen, etc. The user interface 278 also
includes a user-output device (e.g., a LCD display, LEDs, etc.). In
another embodiment, the user interface 278 includes connections for
communication to other interfaces or computers or is located in the
control panel 240 of the refrigeration unit.
[0069] It is envisioned that the controller 192 can use at least
one of a sensed pressure and a sensed temperature to control the
linear compressor, the expansion device, and/or the fans. By
controlling these components, the controller 192 thereby controls
the temperature of the environmental space(s) of the refrigeration
unit. For example, the controller 192 can include a temperature
sensor that senses discharge air temperature. If the discharge air
temperature is outside of a predetermined temperature range (e.g.,
set by an operator), the controller 192 can modulate or change the
volume of the compressor (e.g., increase or decrease the stroke of
the pistons of the compressor). How the controller 192 changes the
compressor volume can be based on empirical test data. Other
methods known to those skilled in the art for controlling the
compressor are possible. Other parameters used by the controller
192 for controlling the compressor can include suction temperature,
suction pressure, discharge pressure, evaporator air exit
temperature, evaporator surface temperature, evaporator pressure,
the temperature difference between discharge and return air
temperature, product zone temperature, product simulator
temperature, and similar parameters.
[0070] Various other features and advantages of the invention are
set forth in the following claims.
* * * * *