Abstrict
A heater element assembly for an electric heater, with a first
and a second spaced element support. The first spaced element support
has a peripheral edge surface and first and second slots extending
inwardly from the edge surface, and an aperture therebetween; and
a resistive heating element including first and second coiled sections
and a connecting section disposed therebetween. The connecting section
includes a mediate loop portion, wherein the first and second coiled
sections are disposed between and engage the first and second spaced
element supports. The connecting section extends through the slots,
and the loop portion extends through the aperture, to secure the
resistive heating element to the first element support.
Claims
What we claim is:
1. A heater element assembly for an electric heater, the assembly
comprising:
first and second spaced element supports, said first spaced element
support having a peripheral edge surface and first and second slots
extending inwardly from said edge surface, and an aperture therebetween;
and
a resistive heating element including first and second coiled sections
and a connecting section disposed therebetween, said connecting
section including a mediate loop portion, wherein said first and
second coiled sections are disposed between and engage said first
and second spaced element supports, and said connecting section
extends through said slots and said loop portion extends through
said aperture to secure said resistive heating element to said first
element support.
2. The assembly of claim 1 including means for securing said heating
element to said second element support, wherein said second spaced
element support has a peripheral edge surface and slots extending
inward from said surface, and an aperture therebetween;
a second connecting section extends through said slots of the second
element support, said second connecting section having a loop portion
extending through said aperture of said second element support.
3. The heater element assembly of claim 1 wherein one of the coiled
sections is in tension.
4. The assembly of claim 1 wherein said heating element includes
at least three coiled sections and respective connecting sections
disposed therebetween, said second spaced element support has a
peripheral edge surface and first and second slots extending inwardly
from said edge surface, and an aperture therebetween and an other
of said connecting sections extends through said slots and said
corresponding loop portion extends through said aperture to secure
said resistive heating element to said second element support.
5. A heater element assembly, the assembly having first and second
spaced element supports and a heater element comprising a plurality
of sequential coiled segments and a respective plurality of linear
segments therebetween, wherein:
the element supports include a plurality of spaced notch openings
separated by at least one aperture in general alignment between
said notch openings,
the heater element is fastened to the first and second element
supports such that the coiled segments pass between the element
supports and the linear segments pass between the spaced notch openings
and,
the linear segment has an intermediate section including a loop
passing through the aperture.
6. The heater element assembly of claim 5 wherein:
the first and second supports are comprised of a semi-rigid material;
and
the linear segment is partially embedded into the support material.
7. The heater element assembly of claim 5 wherein one of the coiled
segments is in tension.
8. The heater element assembly of claim 5 wherein one of the coiled
segment includes a first and second terminal coil, each terminal
coil being adjacent to a linear segment and in contact with a surface
of the element supports.
9. The heater element assembly of claim 5 wherein the element supports
are constructed of mica.
10. An electrical heater assembly comprising:
a first element support spaced apart from a second element support
and,
a heating element having first, second and third portions,
said first portion extending from the first element support to
the second element support,
said second portion connecting the first portion to a third portion,
the second portion having a section that extends through the second
element support towards the first element support and extends back
toward the second element support, and
said third portion extending from the second element support to
the first element support.
11. The electrical heater assembly of claim 10 wherein the first
and third portions of the heating element are heating coils.
12. The electrical heater assembly of claim 10 wherein the second
portion comprises:
a first segment connected to the first portion and extending through
the second element support;
a second segment connecting the first segment to a looped segment,
the looped segment extending through the second element support
toward the first element support; and
a third segment connecting the looped segment to a fourth segment,
the fourth segment extending through the second element support
and connected to the second portion.
13. A method of assembling a heater element assembly for an electric
heater comprising the steps of:
providing first and second spaced element supports, said first
spaced element support having a peripheral edge surface and first
and second slots extending inwardly from said edge surface, and
an aperture therebetween;
providing a resistive heating element including first and second
coiled sections and a connecting section disposed therebetween,
said connecting section including a mediate loop portion;
disposing said first and second coiled sections between and in
engaging relation with said first and second spaced element supports
such that said connecting section extends through said slots; and
extending said loop portion through said aperture to secure said
resistive heating element to said first element support.
14. The method of claim 13, also including the steps of:
providing a heating element which includes at least three coiled
sections and respective connecting sections disposed therebetween,
said second spaced element support having a peripheral edge surface
and first and second slots extending inwardly from said edge surface,
and an aperture therebetween;
extending an other of said connecting sections through said slots
of said second support; and
extending said corresponding loop portion extending through said
aperture of the second support, such that the heating element is
secured to said second element support.
15. A method of assembling a heater element assembly comprising
the steps of:
providing first and second spaced element supports having a plurality
of spaced notch openings separated by at least one aperture in general
alignment between notch openings;
providing a heater element having a plurality of sequential coiled
segments and at least one linear segment between said sequential
coiled segments;
forming a loop in the linear segment;
fastening the heater element to the first and second element supports
such that the coiled segments pass between the element supports
and the linear segments pass between the spaced notch openings and
said loop is aligned with the aperture; and
extending the loop such that the loop passes through the aperture.
Description DESCRIPTION
1. Technical Field
This invention generally relates to heater element assemblies.
More specifically, this invention relates to electrical heater element
assemblies utilized in heat transfer devices, such as space heaters
or cooking devices, and the method of manufacturing such heater
element assembly.
2. Background of the Invention
There are many common heat transfer devices that utilize electrical
heater element assemblies, for example, space heaters. Space heaters
are frequently used to provide heat to an area surrounding the space
heater. Space heaters may provide additional heat to supplement
a primary heat source or may even provide the primary heat source.
Accordingly, space heaters are made in many different sizes with
various heat producing capacities. Relatively low capacity space
heaters are frequently used to provide heat to a localized area
surrounding the space heater. Relatively high capacity space heaters
may heat a larger area and provide a greater increase in the surrounding
temperature. Such heaters may either utilize radiant heat emitted
from a heating element, or may provide for convection heating by
forcing air to pass over a heating element and thereby emit heated
air.
Other examples of appliances which utilize electric heating element
assemblies to emit radiant or convection/radiant heat including
cooking appliances, such as ovens and toasters, as well as hair
drying appliances. Typically, these appliances include heating element
assemblies which utilize a heating coil or filament which is wrapped
around a solid non-conductive material, such as a ceramic rod. Other
such appliances utilize heating coils or filaments attached to a
non-conductive board material, such as mica, by a hook provided
on the mica board, or by simply wrapping the element around the
mica board. In this manner, such existing appliances utilize the
same types of heating element attachment as space heaters. Regardless
of the particular appliance, it is difficult to align the heating
elements in a secure position, while providing even distribution
of the elements over the area of the heating element assembly. It
is particularly difficult to securely fasten a heating element between
a plurality of element support structures.
The present invention is described below in relation to a relatively
small space heater. However, the principles of the present invention
are applicable to larger size and larger capacity space heaters.
The principles of the present invention may also be applicable to
other devices utilizing electrical heater element assemblies, for
example, radiant heaters, convection heaters, toasters, hair dryers,
and toaster ovens.
Existing space heaters have utilized known electrical heater element
assemblies. For example, one known heater element assembly includes
two flat boards that are spaced apart from each other. A heater
wire, which may have a coil shape, extends from one board to the
other board. Opposing ends of sections of the heater wire are connected
to the opposing boards by hooks contained on the boards. With this
type of assembly, the wire (or coil) is simply engaged with the
hook at the ends of the wire, and at sectional points along the
wire.
These existing hooked heater element assemblies exhibit problems.
For example, attaching the heater wire to the hooks is labor intensive
and is difficult to accomplish efficiently. Thus, manufacturing
of hooked heater element assemblies is inefficient and costly. Further,
hooked heater element assemblies may not securely hold the heater
wire taught between the opposing boards, resulting in potential
failure of the heater element attachment, which may cause electrical
shock or fire. Also, the heater wire expands when heated and contracts
as the wire cools. The wire expansion and contraction results in
loose or sloppy heater wires because the wire is not secured taught
against the boards. In the case of convection/radiant heaters, the
heater wire may rattle or move when a fan blows air over the wire.
Another known heater element assembly includes a single flat board
having a series of spaced openings through the board. A ribbon heater
element is woven through the holes, looped back and forth to form
a woven zig-zag type pattern. Each hole in the board has two legs
of a loop extending through the hole. In this manner, the ribbon
heater element weaves through the holes and extends away from one
or both sides of the board. This heater element assembly may also
have two opposed flat boards, whereby the ribbon weaves through
the holes in both boards, such that the ribbon extends between the
boards and beyond the opposite sides of each board.
These existing heater element assemblies using ribbon heater strips
also exhibit problems. For example, the ribbon heater strips are
susceptible to deformation or misalignment, such as may result from
handling of the appliance during shipment, or dropping and sudden
jolting of the appliance during use, or by some object coming into
contact with the ribbon element. Deformation or misalignment of
the heating element may result in failure of uniform heating, electrical
shock or fire. Further, the ribbon is subject to breakage, resulting
in potential catastrophic failure of the heating element. Also,
since the effectiveness of the heating element is often a function
of the amount of element surface area in a given space, using a
ribbon heating element would likely necessitate a large matrix of
looped ribbon sections, and the use of such ribbon element arrangements
has very limited use in radiant heater appliances in the absence
of convection.
Therefore, a need exists to improve heater element assemblies.
There is a need to improve the efficiency and cost of manufacturing
heater element. assemblies and to improve the attachment of a heater
element to a support. The present invention satisfies this and other
needs to improve electrical heater element, assemblies. The present
invention securely attaches heater elements to opposing support
boards by pressing portions of the element through holes in the
boards. The heater elements remain securely fastened to, and taught
against, the support boards. Further, the use of hooks to secure
the elements are eliminated, and the heating element is secured
in a manner which permits even distribution of the heating element
across the heating element assembly.
Other aspects and advantages of the present invention will become
apparent after reading this disclosure, including the claims, and
reviewing the accompanying drawings.
SUMMARY OF THE INVENTION
The present invention provides a heater element assembly for an
electric heater comprising a first and a second spaced element support.
The first spaced element support has a peripheral edge surface and
first and second slots extending inwardly from the edge surface,
and an aperture therebetween. The invention also provides a resistive
heating element including first and second coiled sections and a
connecting section disposed therebetween. The connecting section
includes a mediate loop portion, wherein the first and second coiled
sections are disposed between and engage the first and second spaced
element supports. The connecting section extends through the slots,
and the loop portion extends through the aperture, to secure the
resistive heating element to the first element support.
The present invention further provides a method of assembling a
heater element assembly for an electric heater, comprising the steps
of providing a first and a second spaced element support, the first
spaced element support having a peripheral edge surface and first
and second slots extending inwardly from the edge surface, and an
aperture therebetween. The method includes providing a resistive
heating element including first and second coiled sections and a
connecting section disposed therebetween, the connecting section
including a mediate loop portion. The method further including disposing
the first and second coiled sections between and in engaging relation
with the first and second spaced element supports such that the
connecting section extends through the slots, and extending the
loop portion through the aperture to secure the resistive heating
element to the first element support.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a space heater containing a heater
element assembly made in accordance with the principles of the present
invention.
FIG. 2 is a perspective view of a portion of the heater element
assembly of FIG. 1.
FIG. 3 is a cross-sectional view of the heater element assembly
of FIG. 2 along the line 3--3.
FIG. 4 is an enlarged view of a portion of FIG. 3 showing a heater
element mounted on an element support.
FIG. 5 is a bottom view of the heater element assembly of FIG.
2.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Although the present invention can be made in many different forms,
the preferred embodiments are described in this disclosure and shown
in the attached drawings. This disclosure exemplifies the principles
of the present invention and does not limit the broad aspects of
the invention only to the illustrated embodiments.
FIG. 1 shows a perspective view of a space heater 10 containing
a heater element assembly 12 made in accordance with the principles
of the present invention. The space heater 10 also includes a heater
housing 14 (partially shown and in phantom lines), an element housing
16 containing the heater element assembly 12, a back panel 18, and
a front grill (not shown). An on.backslash.off control switch 20,
a thermostat 22, a pair of indicator lights 24, and a fan 26 are
mounted on the back panel 18 of the space heater 10. Appropriate
wiring is provided to electrically connect the electrical components
of the space heater 10. A bracket plurality 28 (shown as a single
U-shaped bracket) is removably fastened to the back panel 18 and
to the element housing 16 to position the element housing 16 in
relation to the blades of the fan 26. The on.backslash.off switch
20 may be a four-position switch, including the positions of 1)
heater off and fan off, 2) fan on and heat off, 3) fan on and heat
on low, and 4) fan on and heat on high. The heater housing 14 and
the back panel 18 may include air vents or louvers (not shown) to
permit air flow through the space heater 10.
The heater element assembly 12 is slidably mounted on the element
housing 16. The element housing 16 has an open front side and an
opposed open back side (not shown). The back side opening is circular
to coincide with the fan blades of a fan 26. The element housing
16 includes tabs 30 which extend from a front edge of the front
side of the element housing 16. The top tab 30 extends vertically
from the front edge at an angle of approximately 90.degree. from
the top of the element housing 16. The bottom, right, and left tabs
30 extend from the front edge at an angle of approximately 90.degree.
to the bottom, right, and left sides, respectively, of the element
housing 16. The tabs 30 are provided to abut the inside of the heater
housing 14 when the space heater 10 is completely assembled.
The element housing 16 provides a slot 32a near the top of the
right side and a corresponding slot 32b near the top of the left
side. Similarly, a slot 32c is provided near the bottom of the right
side and a corresponding slot 32d is provided near the bottom of
the left side. The slots 32a-32d may also extend through the tabs
30 on the right side and the left side of the element housing 16.
The slots 32a-32d are provided for slidably and removable mounting
the heating element assembly 12 on the element housing 16.
FIG. 2 shows a perspective view of a portion of the heater element
assembly 12 of FIG. 1. The heater element assembly 12 includes a
top element support 34, a bottom element support 36, and a heater
element 38. The top element support 34 is spaced apart from the
bottom element support 36 and the heater element 38 is supported
by and extends from one element support to the other element support.
The top element support 34 is made from an electrical insulation
material, for example, mica board or a mylar and ceramic material.
The top element support 34 has heat resistant properties to withstand
the temperatures generated by the heater element assembly 12. The
bottom element support 36 is similar to the top element support
34.
The top and bottom element supports 34, 36 have a series of alternating
slots 40 and aperture 42 for mounting the heater element 38. Referring
to the top element support 34, the slot 40 includes a notched portion
44 adjacent on edge 46 of the top element support 34. The slot 40
also includes a straight portion 48 extending from the notched portion
44 into the top element support 34. The notch 44 is V-shaped and
has a relatively wide opening at the edge 46 of the top element
support 34 and narrows to a smaller opening that merges with the
straight portion 48.
As shown in FIG. 5, the V-shaped notch 44 at one end of the bottom
element support 36 may have a wider opening 50 than the openings
52 in the other V-shaped notches. The top element support 34 may
also have a V-shaped notch with a wider opening than the opening
in the other notches in the top element support 34.
Referring to FIG. 2, the aperture 42 are preferably round; but,
the aperture 42 may be made in other shapes, for example, square.
The slots 40 and aperture 42 are alternately arranged such that
a aperture 42 is positioned between two slots 40 and a slot 40 is
positioned between two apertures 42. However, as shown in FIG. 5,
the top and bottom element supports 34, 36 have slots 40 at the
outside edges of the element supports.
Referring to FIG. 1, the heater element assembly 12 is shown assembled
onto the element housing 16. Particularly, the top element support
34 is slidably engaged in the slots 32 near the top of the right
and left sides of the element housing 16. Likewise, the bottom element
support 36 is slidably engaged in the slots 32 near the bottom of
the right and left sides of the element housing 16.
The top and bottom element supports 34, 36 may have other holes
or perforations. For example, FIG. 1 shows a hole located approximately
near the center of the top element support 34. The hole 54 may be
used for additional fastening of the top element support 34 to the
element housing 16.
Referring to FIG. 2, the heater element 38 is an element, such
as a wire, that generates heat as electrical current flows through
the wire due to the wire's resistance to the electrical current
flow. Accordingly, the heater element 38 is electrically connected
to the controls of the space heater 10. The heater element 38 is
supported by and extends from the bottom element support 36 to the
top element support 34 as described in greater detail below in regards
to FIGS. 3-5. The heater element 38 is shown in FIG. 2 as wire formed
into a series of spaced coils 56 having a circular shape, and separated
by a series of linear segments Alternatively, the heater element
38 could be made in many different forms, for example a straight
wire between the two element supports 34, 36, a wire formed into
a "zig zag" shaped pattern, or a coil having a square
or other shape.
FIG. 3 shows a cross-sectional view of the heater element 12 assembly
of FIG. 2 along the line 3--3. The heater element 38 is a continuous
wire formed into a series of coils 56 that are aligned in a row.
Each coil 56 is spaced apart from an adjacent coil 56 by a linear
segment 58 of the wire element 38. The heater element wire 38 has
two ends 38a, 38b. Each end 38a, 38b of the wire element 38 terminates
at the outside coils of the row of coils 56. Although not shown,
the wire element ends 38a, 38b are electrically connected to the
controls of the space heater 10 and to an electrical power source.
The wire element ends 38a, 38b may also be fastened to the element
supports 34, 36 by conventional means.
As shown in FIG. 3, each coil 56 extends from one element support
34 or 36 to the other element support 34 or 36. The end 38a of the
heater element wire 38 is fastened to the top element support 34.
The wire element 38 passes down through the straight portion 48
of the slot 40 in the top element support 34 and connects to the
coil 56. The coil 56 extends downward to the bottom element support
36. At the bottom of the coil 56, the wire element 38 passes down
through the straight portion 48 of the slot 40 in the bottom element
support 36, loops up and down through the bottom aperture 42, and
extends upward through the next slot 40 in the bottom element support
36. The wire element 38 connects to the next coil 56 which extends
upward to the top element support 34. This pattern is repeated for
the desired number of coils 56. The end 38b of the last coil 56
passes through the last slot 40 and is fastened to top element support
34.
The present invention is described as shown in FIG. 3 with the
end 38a of the first coil 56 attached to the top element support
34. However, the end 38a of the first coil 56 could be fastened
to the bottom element support 36. Accordingly, the above references
to upward and downward directions are arbitrary and could be reversed.
Referring to FIG. 4, the mounting of the heater element wire 38
to the top element support 34 is shown in greater detail. The heater
element wire 38 comprises a coil 56 extending upward from the bottom
element support 36. The coil 56 is connected to a linear segment
58 that passes upward through a first straight portion 48a of a
first slot 40a. The linear segment 58 includes a transverse section
60 that extends from the terminal end of the coil 56. The transverse
section 60 is positioned on a side 72 of the top element support
34 that faces away from the bottom element support 36.
The linear segment 58 includes a loop segment 62 that passes through
the aperture 42. The loop segment 62 comprises a first leg 64 connected
to the transverse section 60 and extends downward through the aperture
42 towards the bottom element support 34. A second leg 66 of the
loop segment 62 is connected to the first leg 64 and extends back
upward through the aperture 42. The loop segment 62, particularly
the second leg 66, is connected to a second transverse segment 68
that extends from the aperture 42 along side 72, to a transition
in segment 70 of the elements 38.
The loop segment 62 extends downward through the aperture 42 toward
the bottom element support 34 to draw the coils 56 toward the element
supports 34, 36, such that the terminal ends 56a, 56b (FIG. 3) contact
and abut against the ends of the coils 56. Accordingly, the coils
56 are maintained taught against the top and bottom element supports
34, 36, providing secure attachment and minimizing the amount of
slack in the coils 56. The coils 56 remain taught against the top
and bottom element supports 34, 36 even after repeated heating and
cooling of the heater element 38.
Portions of the heater element wire 38 may be embedded into the
element supports 34, 36. Particularly, portions of the linear segment
58, transverse section 60, loop segment 62, and the second transverse
section segment 68 may be embedded into the element supports 34,
36. Embedding the element 38 into the element supports 34, 36 further
secures the element 38 to the element supports 34, 36 and assists
in retaining tension on the coils 56.
FIG. 5 shows a bottom view of the heater element assembly 12 of
FIG. 2. The shape of the slots 40 and the apertures 42 are shown
more clearly in FIG. The apertures 42 are shown as being round,
but may be made in any desired shape. As discussed above, the slots
40 have a V-shaped notch 44 adjacent the edge 46 of the element
support 36. The V-shaped notch 44 extends inward into the element
support 36 and merges with a straight portion 48 which extends further
into the element support 36. The V-shaped notch 44 facilitates insertion
of the heater element 38 into the slot 40 and particularly into
the straight portion 48. Of course, slots 40 having other shapes
may also be used.
FIGS. 2, 3, and 5 show the heater element assembly 12 having a
single row of coils 56. However, multiple rows of coils 56 may be
provided. For example, FIG. 1 shows two rows of coils 56. Each row
of coils 56 may be made from separate heater element wires 38. Alternatively,
a continuous single wire element 38 may be used to form all of the
coils 56. As discussed above, the coils 56 are preferably oriented
in rows. However, the coils 56 could be oriented in other patterns
if desired.
During manufacture of the heater element assembly 12, heater element
supports 34, 36 are made from mica board. Preferably, the top element
support 34 and the bottom element support 36 are the same. The apertures
42 and slots 40 are formed in the mica board element supports 34,
36. The element supports 34, 36 are positioned at a predetermined
distance apart from each other.
The element 38 is preferably constructed from a continuous coil
which is subsequently altered by stretching portions of the coil
to form linear segments 58 separated by coil segments 56. This may
be done by conventional wire coil forming techniques. The element
38 is then bent at select areas such that the coils are in general
alignment for securing in the heater element assembly. In the preferred
embodiment, a right angle bend is provided in the element 38 at
each end of the coils, and the coils are adjacent to and parallel
with one another. The coils are preferably shorter than the space
provided between the element supports. In this manner, the coil
of the element 38, once secured in position between the element
supports 34, 36, are in tension.
Preferably, alignment of the element 38 with the element supports
34, 36 is facilitated by providing a small loop, or dimple, (not
shown) in the element 38 in each linear segment. This small loop,
or dimple, is formed in the linear segment at a position which is
in alignment with the aperture of the respective element support
34, 36. In this embodiment, the small dimple engages the aperture
42 when the element 38 is positioned in place for securing the element
38 to the element supports 34, 36. The element 38 is then secured
to the element supports 34, 36 by the force of a staking tool, which
extends the element 38 through the aperture 42, thereby forming
an extended loop 62 of the element 38. In the embodiment in which
the element support (34, 36) is constructed of a thin board constructed
of mica, of similar non-conductive material, the element 38 is partially
embedded into the element support when the loop 62 is extended through
the aperture 42. Regardless of the type of material used for the
element supports, however, the operation of extending the loop 62
through the aperture 42 causes the coil portions 56 of the element
38 to be drawn toward the respective element support, thereby increasing
the tension on the coil portion and causing the terminal ends 56a,
56b of the respective coil 56 to engage the surface of the respective
element support 34, 36.
While the preferred embodiments have been illustrated and described,
numerous changes and modifications can be made without significantly
departing from the spirit and scope of this invention. Therefore,
the inventors intend that such changes and modifications be covered
by the appended claims. |