Abstrict
Air conditioning apparatus is provided in which an air blower and
an electric heater assembly are located in a common housing with
the heater assembly projecting into the housing from a wall thereof
in transverse relationship to the blower. This configuration eliminates
the need for a dedicated space for the electric heater downstream
of the blower housing, which reduces the size of the apparatus.
The wall of the housing includes an opening through which the heater
assembly is insertable into the housing. The heater assembly includes
a mounting plate to close off the wall opening and to removably
mount the heater assembly with the housing. The heater assembly
preferably further includes an open coil electric heater, with a
major dimension of the heater being oriented generally parallel
to the direction of air flow in the blower housing.
Claims
2. In air conditioning apparatus having a cabinet containing a
blower assembly, said blower assembly having an air blower for moving
air through said cabinet in a predetermined direction and a housing
in which said blower is located, wherein the improvement comprises
an electric heater assembly projecting into said housing from a
wall thereof in transverse relationship to said blower with respect
to said predetermined direction, said heater assembly being removably
mounted with said wall, said heater assembly having a major dimension
and a minor dimension, said major dimension being generally parallel
to said predetermined direction.
3. The apparatus of claim 2 wherein said heater assembly is comprised
of at least one heating coil having a major dimension extending
generally parallel to said predetermined direction.
4. The apparatus of claim 3 further including at least one insulator
extending between adjacent portions of said at least one coil, said
at least one insulator having a major surface and a minor surface,
said major surface being generally parallel to said predetermined
direction.
5. The apparatus of claim 3 wherein said blower is a centrifugal
blower adapted to discharge air transversely toward said heater
assembly and along said major dimension of said at least one coil.
6. (canceled)
7. (canceled)
8. The apparatus of claim 2 wherein said heater assembly includes
at least one generally U-shaped heating coil having parallel legs
extending along a major dimension of said coil and a curved portion
connecting said legs.
9. The apparatus of claim 2 wherein said housing has an open mouth
through which air is dischargeable by said blower in said predetermined
direction, said wall having a relatively flat portion and a curved
portion, said heater assembly projecting into said housing from
said relatively flat portion.
10. The apparatus of claim 9 wherein said heater assembly includes
at least one heating element and a relatively flat plate on which
said heating element is mounted, said heating element being insertable
into said housing through an opening in said relatively flat portion,
said plate being removably mounted with said wall to close off said
opening and to define at least part of said relatively flat portion.
11. Air conditioning apparatus, comprising: a cabinet having a
blower assembly located therein, said blower assembly including
an air blower for moving air through said cabinet in a predetermined
direction and a housing in which said blower is located; and an
electric heater assembly projecting into said housing from a wall
thereof, said heater assembly including at least one heating coil
having a major dimension extending generally parallel to said predetermined
direction.
12. The apparatus of claim 11 wherein said heater assembly includes
plural heating coils in parallel array, each of said coils being
generally U-shaped with parallel legs extending along said major
dimension and a curved portion connecting said legs.
13. The apparatus of claim 12 further including at least one insulator
extending between the legs of each coil, said at least one insulator
having a major surface and a minor surface, said major surface being
oriented generally parallel to said predetermined direction.
14. The apparatus of claim 11 wherein said coil is positioned in
transverse relationship to said blower relative to said predetermined
direction.
15. The apparatus of claim 11 wherein said housing has an open
mouth through which air is dischargeable by said blower in said
predetermined direction, said wall having a relatively flat portion
and a curved portion, said heater assembly projecting into said
housing from said relatively flat portion.
16. The apparatus of claim 15 wherein said heater assembly includes
at least one heating element and a relatively flat plate on which
said heating element is mounted, said heating element being insertable
into said housing through an opening in said relatively flat portion,
said plate being removably mounted with said wall to close off said
opening and to define at least part of said relatively flat portion.
17. (canceled)
18. The apparatus of claim 22 wherein said electric heater includes
at least one heating element and a relatively flat plate on which
said heating element is mounted, said heating element being insertable
into said housing through an opening in said relatively flat portion,
said plate being removably mounted with said wall to close off said
opening and to define at least part of said relatively flat portion.
19. The apparatus of claim 22 wherein said electric heater includes
at least one heating coil oriented generally parallel to said predetermined
direction, said coil having a relatively straight portion that is
generally parallel to said relatively flat portion of said wall
and a curved portion that is generally parallel to said curved portion
of said wall.
20. The apparatus of claim 22 wherein electric heater includes
at least one generally U-shaped coil having parallel legs extending
along said predetermined direction, each leg having a relatively
straight portion that is generally parallel to said relatively flat
portion of said wall and a curved portion that is generally parallel
to said curved portion of said wall.
21. Air conditioning apparatus, comprising: a cabinet having a
blower assembly located therein, said blower assembly including
an air blower for moving air through said cabinet in a predetermined
direction and a housing in which said blower is located, said housing
having an open mouth through which air is dischargeable by said
blower in said predetermined direction; and an electric heater electric
heater assembly projecting into said housing from a wall thereof
and being removably mounted with said wall, said electric heater
being positioned laterally with respect to said blower, said blower
being operable to move air laterally toward said electric heater
and upwardly therethrough before the air is discharged from said
housing though said open mouth.
22. The apparatus of claim 21 wherein said housing has a wall with
a curved portion and a relatively flat portion, said electric heater
projecting into said housing from said relatively flat portion.
Description TECHNICAL FIELD
[0001] This invention relates generally to air conditioning apparatus
and in particular to air conditioning apparatus that includes an
electric heater.
BACKGROUND ART
[0002] The indoor unit of an air conditioning system, which often
is referred to as an air handler, typically includes a cabinet having
at least a filter section, a heat exchanger section and a blower
section. In electrically powered heating/cooling systems, such as
heat pumps, the air handler usually also includes an electric heating
section having one or more electric heating elements. The heating
section is usually located downstream of the blower section in relation
to the direction of air flow in the cabinet. One such air handler
is shown and described in U.S. Pat. No. 3,977,467.
[0003] In operation, air to be cooled or heated is drawn into the
cabinet through a return air duct and is first passed through a
filter in the filter section to remove dirt and other debris. After
the air passes through the filter, it flows across a heat exchanger
coil in the heat exchanger section, which communicates with the
suction side of an air blower in the blower section. The blower
then discharges the air through the electric heating section into
a supply duct that communicates with an indoor space. When the heating/cooling
system (e.g., a heat pump system) is operated in a cooling mode
and a vapor compression refrigerant is used as the heat transfer
fluid, the heat exchanger coil functions as an evaporator to cool
the air that flows through the heat exchanger section by vaporization
of the refrigerant in the heat exchanger tubes. When the system
is operated in a heating mode, the heat exchanger coil functions
as a condenser to heat the air by condensation of the refrigerant.
The electric heating elements are typically used at the beginning
of a heating cycle and may also be used during the heating cycle
to supplement the heating provided by the heat exchanger coil.
[0004] It is also known in the art to provide an elongated electrically
resistive heating element in the blower section. Such heating element
is permanently affixed in the blower section and is at least partially
wrapped around the blower. Although this configuration eliminates
the need for a dedicated electric heating section downstream of
the blower section, the heating element is not field-replaceable
to accommodate different electrical heating capacities.
SUMMARY OF THE INVENTION
[0005] In accordance with the present invention, air conditioning
apparatus is provided in which an air blower and an electric heating
assembly are located in a common housing and the heating assembly
is removably mounted with the housing. This configuration eliminates
the need for a dedicated section in the apparatus for the electric
heater downstream of the blower section, which reduces the size
of the apparatus. Further, the removability feature facilitates
replacement of the heater assembly in the field if a different capacity
heater assembly is desired or in the event of a component malfunction.
[0006] In accordance with one aspect of the invention, the heater
assembly is removably mounted with a wall of the housing, such that
the heater assembly projects into the housing in transverse relationship
to the blower with respect to the general direction of air flow
in the housing. In accordance with another aspect of the invention,
the heater assembly is comprised of at least one heating element
having a major dimension that is generally parallel to the direction
of air flow.
[0007] In accordance with one embodiment of the invention, the
heating element has at least one insulator extending between adjacent
portions of the element. The insulator has a major surface and a
minor surface, with the major surface being oriented generally parallel
to the direction of air flow so as not to restrict air flow.
[0008] In accordance with another embodiment of the invention,
the blower housing has an open mouth through which air is dischargeable
by the blower, a relatively flat portion and a curved portion. The
heater assembly projects into the housing from the relatively flat
portion. The heater assembly includes a relatively flat mounting
plate and is insertable into the blower housing through an opening
in the relatively flat portion. The plate is mounted with the housing
to close off the opening and defines at least a part of the relatively
flat portion.
[0009] In accordance with still another embodiment of the invention,
the electrical heater is comprised of plural electrically resistive
heating elements in an open coil configuration. Each element is
comprised of a generally U-shaped coil that follows the general
contour of the blower housing adjacent the coil. A major dimension
of the coil is parallel to the general direction of air flow in
the blower housing.
BRIEF DESCRIPTION OF DRAWINGS
[0010] FIG. 1 is a perspective view of a blower housing containing
an air blower and electrical heating elements, according to the
present invention;
[0011] FIG. 2 is a top plan view of the blower housing of FIG.
1;
[0012] FIG. 3 is a side elevation view of the blower housing of
FIG. 1, with a portion of the housing cut away to show an electrical
heating element;
[0013] FIG. 4 is a right side elevation view of an air conditioning
unit according to the present invention;
[0014] FIG. 5 is a right side elevation view of a prior art air
conditioning unit;
[0015] FIG. 6 is a front elevation view of the air conditioning
unit of FIG. 4;
[0016] FIG. 7 is a front elevation view of the air conditioning
unit of FIG. 5;
[0017] FIG. 8 is a perspective view of the air conditioning unit
of FIG. 4;
[0018] FIG. 9 is a perspective view of the air conditioning unit
of FIG. 5; and
[0019] FIG. 10 is a front elevation view of an electrical heating
element according to the present invention.
BEST MODE FOR CARRYING OUT THE INVENTION
[0020] The best mode for carrying out the invention will now be
described with reference to the accompanying drawings. Like parts
are marked in the specification and drawings with the same respective
reference numbers. In some instances, proportions may have been
exaggerated in order to depict certain features of the invention.
[0021] Referring now to FIGS. 5, 7 and 9, a conventional air handling
unit 10 used in an electrically powered heating/cooling system,
such as a heat pump system, is depicted in an upright position for
"upflow" operation. Unit 10 includes a cabinet 11, which
houses, from bottom to top, a filter section 12, a heat exchanger
section 14, a blower section 16 and an electrical heating section
18. In operation, air to be cooled or heated is drawn into cabinet
11 by an air blower 17 in blower section 16 through a return air
duct 19 in communication with the lower front portion of cabinet
11, as indicated by directional arrows 20 in FIGS. 5 and 9, and
is first passed through a filter 21 in filter section 12 to remove
dirt and other debris, as indicated by directional arrows 23 in
FIG. 5. After the air passes through filter section 12, it is drawn
upwardly by blower 17 through a heat exchanger coil 22 in heat exchanger
section 14 into blower section 16 and is then discharged through
electrical heating section 18 into a discharge conduit 24, as indicated
by directional arrows 25 in FIGS. 5 and 9. Heat exchanger 22 is
shown as a conventional tube and fin heat exchanger of the "A-coil"
type. A drain pan 27 is located beneath coil 22 to capture condensate
runoff therefrom.
[0022] When unit 10 is operated in a cooling mode, heat exchanger
coil 22 is operative to transfer heat from the air to the heat transfer
medium inside the tubes (e.g., by evaporation of the refrigerant
when a vapor compression refrigerant is used as the heat transfer
medium). Electrical heating section 18 includes plural electrical
heating elements 26 in an open coil configuration. Heating elements
26 are inoperative in the cooling mode. When unit 10 is operated
in a heating mode, coil 22 transfers heat from the heat transfer
medium to the air (e.g., by condensation of the refrigerant when
a vapor compression refrigerant is used as the heat transfer medium).
Heat exchanger section 14 communicates with the suction side of
blower 17. Blower 17 draws air upwardly through heat exchanger 22
and discharges the air into electric heating section 18, wherein
the air is heated by electrical heating elements 26 when elements
26 are operative (i.e., typically at the beginning of a heating
cycle or whenever supplemental heating is needed). Supply duct 24
communicates between the top portion of cabinet 11 and an indoor
space (not shown).
[0023] The longitudinal or major axis of each heating element 26
is generally perpendicular to the direction in which air is discharged
by blower 17 through heating section 18. Blower 17 is contained
in a housing 28 that includes a relatively flat portion 28a and
a curved portion 28b, as can be best seen in FIG. 5. Housing 28
is inserted into cabinet 11 through an opening in the front thereof,
which is provided by removing a front panel-(not shown) of cabinet
11, such that relatively flat portion 28a is inserted first and
faces the closed back portion of cabinet 11, with curved portion
28b facing toward the front.
[0024] Referring now to FIGS. 4, 6 and 8, an air handling unit
30 according to the present invention is also depicted in an upright
position for "upflow" operation. Unit 30 has essentially
the same configuration as the prior art unit 10 described hereinabove
with reference to FIGS. 5, 7 and 9, except that unit 30 does not
have a dedicated electric heating section downstream of the blower
section 34. Instead, a heater assembly comprised of plural heating
elements 32 and an air blower 36 are both located in a housing 38
in blower section 34. The heater assembly is located in housing
38 in transverse relationship to blower 36 with respect to the general
vertical direction of air flow in cabinet 40 of unit 30, as indicated
by directional arrows 23 and 25 in FIG. 5.
[0025] Referring also to FIGS. 1-3, blower 36 is preferably a blower
of the centrifugal "squirrel cage" type for discharging
air radially outwardly by rotation of blower blades 36a. Housing
38 has an open mouth 38a through which air is dischargeable from
housing 38. The wall of housing 38 includes a relatively flat portion
38b and a curved portion 38c. The heater assembly projects into
blower housing 38 from relatively flat portion 38b. Heating elements
32 are preferably mounted on a relatively flat plate 42 and are
insertable into housing 38 through an opening or cutout (not shown)
in relatively flat portion 38b. Plate 42 is removably mounted with
relatively flat portion 38b to close off the opening or cutout in
relatively flat portion 38b, such that plate 42 defines at least
a part of relatively flat portion 38b. By removably mounting the
heater assembly with blower housing 38, the heater assembly is replaceable
in the field if a different capacity heater assembly is desired
or in the event of a component malfunction.
[0026] To facilitate access to the heater assembly, housing 38
is inserted into cabinet 40 of unit 30 through the open front thereof
by inserting curved portion 38c first, such that relatively flat
portion 38b faces the open front of cabinet 40. Flanges 43 on opposed
sides of housing 38 facilitate the insertion of housing 38 into
cabinet 40 and the mounting of housing 38 with respect to cabinet
40. One skilled in the art will recognize that housing 38 is oriented
in the opposite direction from housing 28 in the prior art unit
10 described hereinabove with reference to FIGS. 5, 7 and 9, as
can be best seen by comparing FIGS. 4 and 5.
[0027] The heater assembly shown in FIGS. 1-4, 6 and 8 is comprised
of two distinct heating elements 32, each having an electrically
resistive heating coil 44 in an open coil configuration. However,
one skilled in the art will recognize that the heater assembly may
have more or fewer than two distinct heating elements 32. Referring
also to FIG. 10, each heating coil 44 is oriented vertically, such
that its major dimension is generally parallel to the direction
of air flow in housing 38. Further, each coil 44 is generally U-shaped,
as can be best seen in FIG. 10, and is comprised of two parallel
legs 44a extending along the major dimension of coil 44 with a curved
portion 44b connecting legs 44a. As can be best seen in FIG. 3,
each leg 44a has a relatively straight upper portion and a slightly
inwardly curved lower portion, such that each leg 44a follows the
contour of the portion of the wall of housing 38 adjacent to coil
44. Specifically, the upper portion of each leg 44a is generally
parallel to relatively flat portion 38b and the lower portion of
each leg 44a is generally parallel to curved portion 38b. Ceramic
insulators 46 are interposed between the legs 44a of each coil 44
to insulate coils 44 from the metal mounting members 48 used to
mount coils 44 in relatively fixed positions within housing 38.
Insulators 46 are relatively flat and are oriented with their respective
major faces parallel to the major dimensions of the corresponding
coil 44.
[0028] In operation, blower 36 blows air transversely outwardly
toward the bottom of coils 44 and upwardly therethrough, whereby
the air is heated. By orienting coils 44 so that their respective
major dimensions are generally parallel to the air flow, the air
is heated along the entire length of each coil 44 to enhance heating
efficiency. Further, by orienting coils 44 and insulators 46 parallel
to the air flow, the air flow is not substantially restricted by
these components. For example, in an air handler for a 3-ton air
conditioning system having 1200 cubic feet per minute air flow capacity,
each coil 44 may have a length along its major dimension of about
12 inches, with the relatively straight upper portion of each leg
44a comprising about five inches of the overall 12 inch length.
Each coil 44 may be comprised of 16 or 18 gage wire in a spiral
wound configuration, with a diameter of about 0.675 inch.
[0029] By eliminating a dedicated electric heating section from
the air handler cabinet in accordance with the present invention,
the size of the air handler may be reduced by as much as 10 inches
in comparison to prior art air handlers of similar capacities. This
size reduction allows an air handler unit according to the present
invention to be installed in more restricted spaces than would otherwise
be possible and reduces the cost of the air handler.
[0030] The best mode for carrying out the invention has now been
described in detail. Since changes in and additions to the above
described best mode can be made without departing from the nature,
spirit and scope of the invention, the invention is not to be limited
to the above-described best mode, but only by the appended claims
and their equivalents. |