Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
... yr .M -. ... ..... . ~..r..x..1 N..,.... i..
CA 02539633 2003-04-11
LOW PROFILE CONDENSING UNIT
The present invention relates to condensing units and, more specifically,
condensing units which are adapted for mounting in a case or housing.
Conventional refrigerated display cases are used in a variety of locations
including
retail locations such as supermarkets, gas stations and convenience stores.
These cases
are provided with refrigeration systems that are used to cool the cases and
the items
stored therein. Current display cases may include a large condensing unit
which sits in
a mechanical room or on the roof of a building. Large refrigeration lines may
be used
to carry refrigerant from a central condensing unit to multiple display cases
within the
store to refrigerate the cases and cool the items located therein.
A disadvantage of using a central condensing unit is that in the event of a
refrigerant leak, the entire refrigeration charge supplying several fluidly
linked
refrigerated cases may leak into the atmosphere. Further, due to the fact that
the cases
are interconnected, a failure of the system may result in the loss of the
refrigeration
capability of all of the interconnected cases.
It is also known to use separate, condensing units for individual refrigerated
cases.
The use of such separate condensing units limits the amount of refrigerant
loss in the
event of a leak and also limits the effect of such a failure to a single
refrigerated case.
The condensing units used with such refrigerated cases, however, are
oftentimes large
and bulky and may have a negative impact on the design and aesthetics of the
refrigerated case in which the condensing unit is mounted.
Figure 2 illustrates a prior art condensing unit 120 which is adapted for use
with an
individual refrigerated display case. Prior art unit 120 includes a vertically
oriented
compressor 122 coupled to a condensor coil 124. A single fan 126 is secured to
condenser 124. Service valves 128 are mounted to base plate 130 and the upper
portion
of valves 128 are adapted to be rotated in 90 degree intervals with respect to
base
portion 132 of valves 128. Base plate 130 includes downwardly bent flanges 134
along
each of its four outer edges. Downwardly extending flanges 134 form a skirt
which
- 1 -
CA 02539633 2003-04-11
encloses a space below base plate 130. Bolts securing compressor 122 and
mounting
brackets 132 have threaded shafts which extend through base plate 130 and
project
into the space enclosed by flanges 134. Nuts are threaded onto the bolt shafts
to secure
the condensing unit components to base plate 130 and are disposed in the space
enclosed by flanges 134. It is also known to turn base plate 130 upside down
for use
with a condensing unit 120 wherein flanges 134 project upwardly.
The invention comprises, in a form thereof, a condensing unit including
a base plate having a first major surface, an oppositely disposed second major
surface
20
wa
2-
CA 02539633 2003-04-11
and an outer periphery. A rotary compressor including a motor having a main
shaft is
mounted on the base plate wherein the main shaft extends substantially
parallel to the
first major surface. A condensing coil is also mounted on the base plate. At
least one
fluid conduit in fluid communication with the compressor and the condensing
coil is
provided wherein the at least one fluid conduit, compressor and condensing
coil define
a fluid circuit. At least one fan is disposed proximate the condensing coil.
The condensing unit may further include an electrical box mounted to the base
plate wherein the electrical box, the compressor and1he condensing coil all
project in a
first direction from the base plate, the first direction being substantially
perpendicular
to the first major surface, and wherein either the compressor or the
condensing coil
project a greater distance in the first direction than the electrical box. The
condensing
coil may be at least partially disposed within a coil housing wherein the at
least one
fan is secured to the coil housing. .
The invention comprises, in another form thereof, a refrigerated display case
which
includes a housing defining a refrigerated space. The housing further defines
a
condenser space having a length, a width and a height wherein the height is
less than
the length and the width. A condensing unit is mounted in the condenser space
and
includes a base plate having a first major surface, an oppositely disposed
second major
surface and an outer periphery. A rotary compressor including a motor having a
main
shaft is mounted on the base plate wherein the main shaft extends
substantially parallel
to the first major surface. A condensing coil is mounted within a coil housing
disposed
on the base plate. At least one fluid conduit in fluid communication with the
compressor and the condensing coil is provided wherein the at least one fluid
conduit,
compressor and condensing coil define a fluid circuit. At least one fan is
mounted to
the coil housing and is positioned to draw air towards the fan across the coil
and blow
air away from the fan across the compressor.
The invention comprises; in another form thereof, a condensing unit including
a
base plate having a first major surface, an oppositely disposed second major
surface
and an outer periphery. A compressor including a motor having a main shaft is
mounted on the base plate wherein the main shaft extends substantially
parallel to the
_ 3-
CA 02539633 2003-04-11
first major surface. A condensing coil is also mounted on the base plate. At
least one
fluid conduit in fluid communication with the compressor mechanism and the
condensing coil is provided wherein the at least one fluid conduit, compressor
and
condensing coil define a fluid circuit. At least one valve and at least one
mounting
bracket are also provided wherein the valve is in fluid communication with the
fluid
circuit. The mounting bracket has a first portion secured to the first major
surface and
a second portion extending outwardly from the first major surface with the
valve being
mounted to the second portion.
n. Y
The condensing unit may further include a a second valve in fluid
communication
with the fluid circuit and a second mounting bracket wherein the second
mounting
bracket is secured to the first major surface and the second valve is mounted
to the
second mounting bracket at a position spaced from the first major surface. The
valves
may be rotatably mounted to the mounting brackets. The base plate may also
have a
configuration defining a central plane and include at least one rigidifying
portion
extending at an angle to the central plane and wherein the second major
surface
defines a bearing surface substantially free of projections.
An advantage of the present invention is that it provides a condensing unit
having a
compact design which thereby facilitates its mounting in a refrigerated case
or air
conditioner. Further, a condensing unit having such a compact design provides
designers of refrigerated cases and air conditioners with greater flexibility
in the
functional and aesthetic design of such equipment.
*==
4-
CA 02539633 2003-04-11
The above-mentioned and other features and objects of this invention, and the
manner of attaining them, will become more apparent and the invention itself
will be
better understood by reference to the following description taken in
conjunction with
the accompanying drawings, wherein:
Figure 1 is a perspective view of a refrigerated display case ;
Figure 2 is a perspective view of a prior art condensing unit;
Figure 3 is a top view of a low profile condensing unit
Figure 4 is a front view of the low profile condensing unit of Figure 3;
Figure 5 is a side view of the low profile condensing unit of Figure 3;
Figure 6 is a top view of a base plate used with the low profile condensing
unit of Figure 3;
Figure 7 is a sectional view of the base plate of Figure 6 taken along line 7-
7;
Figure 8 is a partial sectional view of a service valve mounted to the base
plate of the low profile condensing unit ?
Figure 9 is a top view of the service valve of Figure 8 taken along line 9-9;
Figure 10 is a schematic view of a low profile condensing unit.;
Figure 11 is a graph illustrating performance characteristics of the low
profile condensing unit; and"
Figure 12 is a side view of a self-clinching fastener.
Although the exemplification set out herein illustrates an embodiment of the
invention, in one form, the embodiment disclosed below is not intended to be
exhaustive or to be construed as limiting the scope of the invention to the
precise form
disclosed.
5-
CA 02539633 2003-04-11
Referring to Figure 1, refrigerated display case 26 is provided with
condensing unit
28 mounted in the lower portion thereof. Refrigerated display case 26 may be
placed in
retail establishments for storing and displaying refrigerated items for sale.
Illustrated
display case 26 is provided with sliding doors 30 which include a transparent
panel to
provide visual access to the contents of the refrigerated space defined within
housing
27 of display case 26. Doors 30 are openable to allow customers to gain self-
service
access to the contents of case 26 such as beverages or perishable food items.
Located
in the lower portion of refrigerated display case 26 is compartment 32 in
which
condensing unit 28 is located. Compartment 32 has 'a length, width, and height
with the
height of compartment 32 being substantially less than the length and width.
Except
for condensing unit 28 and its combination with compartment 32, display case
26 has a
conventional construction and is manufactured using conventional methods and
materials.
In the illustrated embodiment, compartment 32 includes a bottom planar surface
70
on which condensing unit 28 is positioned. Alternative embodiments, however,
could
utilize a compartment 32 without a bottom panel member and support condensing
unit
28 using support brackets such as L-shaped angle irons. Such support brackets
could
extend from the front to back of compartment 32 along the outer edges of base
plate 36
and at intermediate locations below base plate 36. A grill (not shown) which
permits
the passage of air therethrough is removably mounted across the lower portion
of case
26 to cover the opening to compartment 32. Figure 1 illustrates case 26 with
the grill
removed to permit access to compartment 32. A grill, or similar feature which
permits
the passage of air therethrough, is located opposite opposite the opening to
compartment 32 on the rear surface of case 26 to facilitate the passage of air
through
compartment 32.
Referring to Figure 3, condensing unit 28 includes compressor 34 mounted to
base
plate 36. Compressor 34 includes a compressor mechanism 31 and a motor 33 with
a
main shaft 35 for driving compressor mechanism 31. Main shaft 35 is oriented
substantially horizontally and, thus, is oriented substantially parallel to
upper surface
52 of base plate 36. Figure 3 schematically illustrates compressor mechanism
31,
motor 33 and main shaft 35. In horizontally oriented compressors such as
compressor
6-
CA 02539633 2009-12-23
34, the compressor assembly, including the main shaft extending between the
compressor mechanism and the motor, although substantially horizontal, will
often be
slightly inclined relative to a horizontal plane to facilitate the operation
of the
compressor, e.g., by facilitating the collection of lubricating oil within the
compressor
at one end thereof.
Compressor 34 may be a HG model rotary compressor that is commercially
available from Tecumseh Products Company located in Tecumseh, Michigan. For
larger capacity applications, HK model rotary compressors also commercially
available from Tecumseh Products Company may be used. A horizontally oriented
twin rotary compressor may also be used with condensing unit 28. U.S. Pat. No.
6,171,076 B1 assigned to assignee of the present invention discloses one such
horizontally oriented twin rotary compressor. Other compressors having a
relatively
low profile may also be used with condensing unit 28. For example, a
horizontally
oriented scroll compressor could also be used with condensing unit 28.
Fluid conduits 38a-38d provide fluid communication between the various
components of condensing unit 28 and together with those components define the
condensing unit fluid circuit 28F. First service valve 48 is a suction valve
and is in
fluid communication with accumulator 47 of compressor 34 through conduit 38a.
Compressor 34 is in fluid communication with condensor coil 54 through conduit
38b. Conduit 38c provides fluid communication between condensor coil 54 and
receiver 46. Conduit 38d provides fluid communication between receiver 46 and
second service valve 49 which is the discharge, valve.
Also mounted to base plate 36 are electrical box 42 and pressure switch 44. As
best shown in Figure 10, pressure switch 44 is in fluid communication with
condensing unit fluid circuit 28F at a first location between suction valve 48
and
accumulator 47 and at a second location between receiver 46 and discharge
valve 49.
Electrical conduits 43a, 43b and 43c extend outwardly from electrical box 42
to
compressor 34, pressure switch 44 and fans 58 respectively for conveying
electrical
power and control lines.
7-
CA 02539633 2003-04-11
As best seen in Figures 4 and 5, the use of a horizontally oriented compressor
34
allows condensing unit 28 to have a relatively low profile or height. The
remainder of
the condenser unit components are sized so as not to significantly exceed the
height of
compressor 34 and thereby provide a compact design for condensing unit 28.
This also,
allows for compartment 32 in refrigerated display case 26 to have a compact
design
thereby facilitating flexibility in the design of display case 26 and
potentially smaller
and sleeker designs of such refrigerated cases.
In the illustrated embodiment and as can be seen in Figure 4, base plate 36
includes
first and second oppositely disposed major planar surfaces 52 and 68. First
major
surface 52 faces in a first direction perpendicular to major surface 52, which
in the
illustrated embodiment is upwardly, and flanges 62, which are substantially
transverse
to first and second major surfaces 52, 68, extend upwardly in the first
direction.
Similarly, all of the condensing unit components are mounted to the first
major surface
and project upwardly in the first direction. Coil housing 56 for condensing
coil 54
projects the greatest distance above upper surface 52 of base plate 36 in the
first
direction as shown by dimension line 56H. Similarly, and as can be seen in
Figure 4,
receiver 46 projects a distance 46H, accumulator 47 which is secured to the
housing of
compressor 34 projects a distance 47H and electrical box 42 projects a
distance 42H
above upper surface 52 of base plate 36. In the illustrated embodiment, height
56H of
housing 56 is approximately seven inches, i.e., 7.224 inches and the maximum
height
of compressor 34 which corresponds to distance 47H is 6.836 inches. In the
illustrated
embodiments, distance 46H falls between distances 54H and 47H and distance 42H
is
less than distances 54H, 46H and 47H.
Condensing coil 54 and coil housing 56 are configured to provide condensing
unit
with a low profile. As can be seen in the Figures, coil housing 56 has a
horizontal
length 56L which is substantially greater than the vertical height 56H of
housing 56.
Coil 54 and housing 56 are located along an edge of base plate 36 to allow
coil 54 and
housing 56 to be positioned near a grill or other openings in housing 27. Fans
58 draw
air from outside case 26 through the grill or openings in housing 27 and
through coil
housing 56 across coil 54 to cool coil 54 and the compressed refrigerant
therein. After
passing across coil 54, fans 58 blow the air towards the opening of
compartment 32
8-
CA 02539633 2003-04-11
shown in Figure I where it exits housing 27 through a removable grill (not
shown)
which covers the opening to compartment 32.
Base plate 36 is illustrated in Figures 6 and 7 and has an outer periphery 60
which,,
in the illustrated embodiment, is defined by four sides and substantially
rectangular.
Illustrated base plate 36 is approximately 20 inches by 20 inches. Other
shapes and
sizes of base plate 36 may also be used with the present invention. Each edge
or side
of illustrated base plate 36 is provided with an upwardly extending flange 62.
Flanges
62 form rigidifying portions which provide base plate 36 with structural
rigidity. By
employing flanges 62 which extend upwardly rather than downwardly, the
vertical
distance that would be occupied by the use of downwardly extending flanges can
be
eliminated, thereby facilitating a reduction in the overall height of
condensing unit 28.
Base plate 36 is provided with a plurality of apertures through which the
threaded
shafts of self-clinching fasteners 64 pass. Self-clinching fasteners 64
together with nuts
66 are used to mount the components of condensing unit 28 to base plate 36
either
directly or.indirectly such as via mounting brackets.
Fasteners 64 have a head located at one end and when secured to base plate 36,
the
head is substantially flush with lower surface 68 of base plate 36 projecting
only a
minimal distance outwardly therefrom. By using fasteners 64 which are
substantially
flush with lower surface 68, lower surface 68 is substantially free of
projections to
facilitate the use of lower surface 68 as a bearing surface for supporting the
weight of
condensing unit 28 and allowing surface 68 to be in direct contact with
substantially
planar mounting surface 70 (Figure 1) of refrigerated display case 26 or other
device
employing the low profile condensing unit 28 of the present invention.
Fasteners 64 may be flush-head studs available from PEM Fastening Systems, a
PennEngineering Company having a place of business at 5190 Old Easton Road,
Danboro, Pennsylvania 18916. In the illustrated embodiment, fasteners 64 are
%2 inch
long self-clinching studs having '/< inch-20 threads sold under part. number
FH-0420-
20-Z1 by PEM Fastening systems except for those fasteners 64 which are used to
secure compressor 34 which are 1.842 inch long self-clinching studs with %
inch-20
9-
CA 02539633 2003-04-11
threads. As shown in Figure 12, such fasteners have a relatively thin head 96
with
circumferentially spaced ribs 98 on the underside of the head positioned
adjacent an
annular groove 100 in shaft 102 proximate head 96. As fastener is secured to
base
plate 36, head 96 is squeezed into the sheet material forming base plate 36
and the
sheet material displaced by head 96 flows around ribs 98 and into annular
groove 100
to secure fasteners 64 to the sheet material forming base plate 36.
Alternative fasteners which do not project substantially beyond lower surface
68 of
base plate 36 may also be used with base plate 36 to secure the condensing
unit
components to base plate 36. The condensing unit components or mounting
brackets
therefor may also be secured to base plate 36 by welding or adhesives and
still
maintain lower surface 68 substantially free of projections. It is
advantageous to use
such fasteners which do not project substantially beyond lower surface 68 of
base plate
36 to enable base plate 36 to be placed on a flat surface within the
refrigerated case
and have lower surface 68 thereby act as a bearing surface. If the fasteners
project to a
large extent, such as by the thickness of a conventional bolt head, and base
plate 36
were placed on a substantially flat planar surface, base plate 36 would likely
deform
base plate 36 sufficiently that surfaces 52 and 68 of base plate 36 would no
longer be
substantially planar. Relatively large projections extending beyond lower
surface 68
would also negatively impact the ability to slide base plate 36 into position
in the
cabinet In alternative embodiments, the base plate could employ rigidifying
portions
which differed in shape or configuration from upwardly extending flanges 62
wherein
the downwardly facing surface of the base plate still provide a bearing
surface
substantially free of projections. Such a bearing surface might not comprise
the
entirety of the downwardly facing base plate surface yet still form a
substantial portion
of such downwardly facing surface and define a bearing surface which provides
sufficient support for the condensing unit to avoid gross deformation of the
base plate.
For example, upwardly projecting ridges or ribs could be formed in the base
plate to
form rigidifying portions and still allow the downwardly facing surface of the
base
plate to define a bearing surface substantially free of projections.
Referring to Figures 8 and 9, service valves 48, 49 are mounted to base plate
36
using brackets 72 that provide orientation flexibility to valves 48, 49.
Brackets 72 are
- 10-
CA 02539633 2003-04-11
provided with first or base portions 76 which are secured to first major
surface 52 and
a second mounting portion 74 extending outwardly from surface 52 with valves
48, 49
being secured to mounting portions 74 at positions spaced from surface 52.
Base
portions 76 are provided with apertures 78 through which fasteners 64 extend
with
nuts 66 being threaded onto the threaded shafts thereof to secure brackets 72
to base
plate 36. Mounting portions 74 are raised above base portions 76 and are
provided
with apertures 80 through which extension portions 82 of valves 48, 49
project.
Shoulder portions 84 of valves 48, 49 rest upon surfaces 86 of mounting
portions 74 to
support valves 48, 49 thereon. Valves 48, 49 may be rotatably secured to
brackets 72
using any suitable method including providing an annular groove 88 in
extension
portion 82 which receives a C-shaped retaining clamp 90. Referring to Figure
9, valves
48, 49 are mounted to brackets 72 so that valves 48, 49 may rotate relative to
brackets
72 as illustrated by arrow 92. Apart from being mounted to brackets 72, valves
48, 49
have a conventional construction. The bodies of valves 48, 49 are rotatable
about the
stem secured to brackets 72 and may be adapted to rotate in intervals of 45 or
90
degrees. The ability to rotate valves 48, 49 and thereby provide for the
variable
orientation of valves 48, 49 facilitates the connection of valves 48, 49 to
evaporator
fluid circuit 94F. Positioning valves 48, 49 proximate the outer periphery of
base plate
36 also facilitates the attachment and detachment of valves 48, 49 from
evaporator
fluid circuit 94F such as during installation of condensing unit 28 or removal
of
condensing unit 28 as might be required for maintenance purposes.
Figure 10 provides a schematic illustration of condensing unit 28 operably
coupled
with an evaporator 94. As shown, valves 48, 49 are coupled to evaporator fluid
circuit
94F to provide fluid communication between fluid circuit 28F of condensing
unit 28
and evaporator fluid circuit 94F. Condensing unit 28 and evaporator 94 operate
in a
conventional manner to cool the interior of refrigerated case 26. As shown in
Figure
10, refrigerant enters condensing unit 28 through suction valve 48 passes
through
conduit 38a and enters accumulator 47. The refrigerant is compressed after
entering
compressor 34 from accumulator 47. The compressed and heated refrigerant is
discharged from compressor 34 and passes through conduit 38b to enter
condenser coil
54. As refrigerant passes through coil 54, air flow generated by fans 58 cool
the
- 11-
CA 02539633 2003-04-11
referigerant. Refrigerant exits coil 54 into conduit 38c which conveys the
refrigerant to
receiver 46. The refrigerant subsequently discharged from condensing unit 28
via
conduit 38d and discharge valve 49. After entering evaporator fluid circuit
94F after
being discharged through valve 49, the refrigerant passes through evaporator
94 and is'
returned to condensing unit 28 through suction valve 48.
Due to the low height and extended length of coil 54 and housing 56, two fans
58
are used with condensing coil 54 instead of a single fan to provide the
necessary air
flow to cool coil 54 and the refrigerant passing therethrough. In the
disclosed
embodiment fans 58 are permanent-split-capacitor tube-axial type fans (part
no.
W2E143-AA15-01) available from EBM Industries Inc. which has a place of
business
at 100 Hyde Road, Farmington, Connecticut 06034. Fans 58 have fan blades which
are
enclosed in a generally cylindrical shroud 59, i.e., fans 58 are tube axial
fans, to
enhance their effectiveness. Fans 58 generate a cooling air flow for
condensing coil 54
as well as for the rest of condensing unit 28. It is desirable for the fans of
condensor
unit 28 to be capable of running at -10% of the maximum rated speed of the
fans when
there is a 0.3 inches water pressure drop across the condensing coil. Due to
the
compact size of condensing unit 28, high efficiency fans having a blade
diameter of
approximately 6 inches may be advantageously employed to obtain the desired
fan
performance. Permanent-split-capacitor fans can be used to provide such a high
efficiency fan. Figure 11 provides a graph of a fan motor curve for
illustrated
condenser unit 28 which employs a pair of tube axial permanent-split-capacitor
fans
58. The graph illustrates a first fan curve, i.e., the solid line, for a fan
having a
frequency of 60 Hz and a second curve, i.e., the dashed line, for a fan having
a
frequency of 50 Hz. In alternative embodiments, three lower efficiency fans
having a
blade diameter of approximately six inches, such as those obtainable from
Morrill
Motors, Inc. a company having a place of business in Erwin, Tennessee (P.O.
Box
531, Erwin, Tennessee, 37650-053 1), may be positioned in cylindrical shrouds
and
substituted for the two high efficiency fans 58. A substantially cylindrical,
cross flow
blower fan having an appropriate shroud and appropriately sized motor may also
be
suitable to provide the desired operating characteristics.
12-
CA 02539633 2003-04-11
While this invention has been described as having an exemplary design, the
present
invention may be further modified within the spirit and scope of this
disclosure. This
application is therefore intended to cover any variations, uses, or
adaptations of the
invention using its general principles.
10
20
13-
