U.S. patent application number 10/916461 was filed with the patent office on 2006-02-16 for heating element compartment for electric dryer applications.
This patent application is currently assigned to AMERICAN DRYER CORP.. Invention is credited to Mark Rapoza.
Application Number | 20060034593 10/916461 |
Document ID | / |
Family ID | 35800066 |
Filed Date | 2006-02-16 |
United States Patent
Application |
20060034593 |
Kind Code |
A1 |
Rapoza; Mark |
February 16, 2006 |
Heating element compartment for electric dryer applications
Abstract
A heating box for an electric heating element is disposed in a
clothes dryer. A substantially rectangular enclosure is opened at a
first end and closed at a second end and internally supports one or
more heating elements. A surface of the enclosure includes a
plurality of holes which allow the heating element along its length
to remain in contact with ambient air. The first end is connected
to the heating duct of the dryer, and air enters through the
plurality of holes and is heated. The air is drawn through the open
end of the heating box due to a negative pressure applied to the
dryer chamber into the dryer. In accordance with a preferred
embodiment, the size of the holes changes along the length of the
enclosure.
Inventors: |
Rapoza; Mark; (Somerset,
MA) |
Correspondence
Address: |
CONNOLLY BOVE LODGE & HUTZ LLP
SUITE 800
1990 M STREET NW
WASHINGTON
DC
20036-3425
US
|
Assignee: |
AMERICAN DRYER CORP.
Fall River
MA
|
Family ID: |
35800066 |
Appl. No.: |
10/916461 |
Filed: |
August 12, 2004 |
Current U.S.
Class: |
392/350 ;
219/536; 392/347 |
Current CPC
Class: |
D06F 58/26 20130101 |
Class at
Publication: |
392/350 ;
392/347; 219/536 |
International
Class: |
F24H 3/00 20060101
F24H003/00 |
Claims
1. A heating box for an electric heating element comprising: an
enclosure open at a first end supporting a heating element and
closed at an opposite end, a surface of said enclosure including a
plurality of holes which allow said heating element along its
length to remain in contact with ambient air, said first end being
open and arranged to deliver heated drying air to a drying chamber
of a laundry dryer.
2. The heating box according to claim 1, wherein said holes are
evenly spaced along said enclosure surface.
3. The heating box according to claim 2, wherein said holes vary in
size from said closed end of said enclosure to the open end of said
enclosure.
4. The heating box according to claim 1, wherein said heating box
has a rectangular cross section.
5. The heating box according to claim 4, wherein each surface of
said heating box includes said holes.
6. The heating box according to claim 4, wherein said plurality of
holes vary in size from said open end to said closed end with
larger holes being located near said closed end.
7. A method for equalizing the temperature distribution across a
heating element comprising: supporting said beating element in an
enclosure, said enclosure being open at one end arranged to deliver
heated drying air to a drying chamber of a laundry dryer and closed
at an opposite end; and locating holes along the length of said
enclosure having a size which varies from one end to another,
whereby the heating element is in contact with the ambient air
along substantially along its entire length.
8. The method for equalizing the temperature distribution across a
heating element according to claim 7, wherein said holes adjacent
an end which delivers hot air are smaller than the holes adjacent
the closed end.
9. The method for equalizing the temperature distribution across a
heating element according to claim 8, wherein said holes are
distributed on each of four surfaces of a rectangular enclosure.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to clothes dryers having
electrical heating elements for generating drying air.
Specifically, a heating box is disclosed for an electric heating
element assembly which increases the heat transfer efficiency of
the heating element.
[0002] Both home and commercial clothes drying devices require
substantial heat generation in order to provide drying air to
remove moisture from articles being dried. Drying air is generated
either from a gas burner or from an electrical heating element
which operates from conventional A/C. In the case of electric
heating, drying air is supplied from a plurality of electrical
elements which are connected to the electrical service in the
facility. A heating box surrounds the heating element, and ambient
air enters one end and is drawn through to the second end into a
drying chamber of the dryer due to a negative pressure created
within the drying chamber from an impeller.
[0003] The life of the electric heating elements are finite, and,
over time, replacement is necessary. The dryer down time as well as
technical support needed to replace the elements is a significant
drawback for this type of dryer which competes with the gas
dryer.
[0004] It has been determined that the life expectancy of the
electric heating elements can be improved by improving the heat
transfer rate from the heating element to the ambient air being
heated for the dryer. As the efficiency goes up, the time of
operation of the heating element decreases, prolonging the life of
the heating elements. The present invention has been designed in an
effort to improve the efficiency of electrically heating drying air
and which will produce a longer useful life for the heating
element.
SUMMARY OF THE INVENTION
[0005] A heating box is provided by an enclosure which encloses a
heating element and has an open end which supplies hot air to the
dryer drying chamber. Ambient air enters holes along the surface of
the enclosure and is heated to a drying temperature. The holes in
the surface of the enclosure have a diameter which varies over the
length of the enclosure. Ambient air is in contact with the entire
length of the heating element creating a more uniform transfer of
heat from the heating element to the ambient air.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] FIG. 1A illustrates a heating box in accordance with the
present invention implemented in a commercial laundry dryer;
[0007] FIG. 1B is an isometric view of the laundry dryer of FIG.
1A;
[0008] FIG. 2 illustrates an exploded view of the heating box of
FIG. 1;
[0009] FIG. 3 illustrates an isometric view of a heating box;
[0010] FIG. 4 is an end view showing connections to the heating
elements in the heating box and the contactor;
[0011] FIG. 5 is a top view of another embodiment of the
invention;
[0012] FIG. 6 is a front view of the embodiment of FIG. 5;
[0013] FIG. 7 is a bottom view of the heating box of the embodiment
of FIGS. 5 and 6; and
[0014] FIG. 8 illustrates the connection to the heating elements in
the heating box.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0015] Referring now to FIGS. 1A and 1B, a section view and
isometric view of a commercial laundry dryer are shown. The laundry
dryer includes a drying drum 12 supported for rotation on bearings
17. An opening 14 to the drying drum 12 is closed by the door
15.
[0016] Drying air is provided to the drying drum 12 from a source
of electric heating elements within a heating box 19 supported by
bracket 21. Air within the heating box 19 enters through a
plurality of opening 31 in the surface of the heating box enclosure
19. Heating box 19 supplies hot air through a duct 20 into an
opening of drying chamber 12.
[0017] The heating box of the preferred embodiment is disclosed
more particularly in FIGS. 2, 3 and 4. The enclosure 25 is
rectangular and includes a plurality of holes 29, 31 on the top
surface thereof as well as 32 and 33 on the side surface thereof.
The bottom 23 is shown having no holes. An open end of the heating
box includes tabs 26 which engage a surface of the dryer forming
the heating duct 20, and the opposite end of the heating box 19 is
closed. The holes along the surface of the heating box are evenly
spaced and generally sized so that the holes decrease in diameter
as the distance from the closed end increases. Thus, the holes 29,
32 near the closed end of the heating box are sized larger than the
holes 31, 33 at the open end of the heating box 19. The effect is
to uniformly distribute ambient air entering through holes 29, 31,
32 and 33 along the length of the heating element. The result is
that heat transfer from the surface of the heating elements is more
uniform than in the conventional arrangement where ambient air
enters through an open, opposite end of a heating box having no
holes along its length. Contactor 24 supplies electrical current to
each of the heating elements 27.
[0018] In a typical configuration, the heating elements of the
prior art would deliver a certain wattage of heat. In the preferred
embodiment of the present invention, the element wattage rating can
be increased and still allow the same element operating
temperatures. Instead of a higher heat output with the larger heat
element, the temperature may be lowered for each of the heating
elements in order to preserve the life of the heating elements. For
instance, a 100.degree. decrease in temperature may double the
element life.
[0019] A second embodiment of the invention is illustrated with
respect to FIGS. 5-8. FIG. 5 represents a top view of a rectangular
heating box which includes holes 41, 42 extending across the top
surface of the heating box. Holes 41 have a smaller diameter than
those identified as 42. Air flows into the holes 41 and 42 and out
the exit opening in the box 45 communicating with the hot air duct
20. The opposite end of the box 49 is closed so that all air flow
must be through holes in the top, sides and bottom of the heating
box.
[0020] The side view of FIG. 5 is shown in FIG. 6, and includes a
plurality of terminals 47 which connect the electrical heating
elements to a contactor 24 which supplies operating current to the
heating elements under control of the dryer controller.
[0021] The side walls of the heating box include a plurality of
channels 48 which support the heating elements in a stacked
arrangement with heating box 19. A heating box support 48 is shown
to support the closed end of the heating box within the dryer.
[0022] FIG. 7 illustrates a bottom view, wherein a plurality of
holes 43, 44 are shown along the length of the heating box 19. As
in the top surface of the heating box, the bottom surface includes
smaller diameter holes at the open end exit 45 and larger holes 44
at the closed end of the heating box 49.
[0023] FIG. 8 illustrates terminals 47 which are connected to the
heating elements and to the contactor by wires (not shown). In the
embodiment shown, it is contemplated that six heating elements
would be provided, each pair of heating elements having a common
terminal with the remaining end of the heating element connected to
one phase of the three phase electrical system.
[0024] Using the principles of the foregoing embodiments, the heat
distribution over the heat elements is distributed more uniformly,
increasing the life of the heating element.
[0025] The foregoing description of the invention illustrates and
describes the present invention. Additionally, the disclosure shows
and describes only the preferred embodiments of the invention in
the context of a heating element compartment for electric dryer
applications, but, as mentioned above, it is to be understood that
the invention is capable of use in various other combinations,
modifications, and environments and is capable of changes or
modifications within the scope of the inventive concept as
expressed herein, commensurate with the above teachings and/or the
skill or knowledge of the relevant art. The embodiments described
hereinabove are further intended to explain best modes known of
practicing the invention and to enable others skilled in the art to
utilize the invention in such, or other, embodiments and with the
various modifications required by the particular applications or
uses of the invention. Accordingly, the description is not intended
to limit the invention to the form or application disclosed herein.
Also, it is intended that the appended claims be construed to
include alternative embodiments.
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