An electric heater incorporating simple support structure therefor.
A frame is insulated from an electric resistance heater coil by
insulated supports mounted within beam members of the frame. The
supports incorporate structural features enabling the use of simplified
supporting beams. The support insulators include additional structural
features for retaining the resistance wire in place and for simplified
engagement therewith. The insulators may project on both sides of
the support beams and retain heater wires in two planes. The support
insulators further provide an integrated structure easily fabricated
and simply assembled to the frame.
What is claimed is:
1. An electric heater comprising a heater coil attached to a base,
said heater coil having a plurality of convolutions of heater wire,
an insulating support for said heater coil having a body portion
cooperating with means for attaching said support to said base,
a first retaining member extending from said body portion in a first
direction, said first retaining member having a first dimension
and a second dimension, in a plane transverse to said first direction,
said first dimension being greater than the spacing between adjacent
convolutions of said heater coil and said second dimension being
transverse to said first dimension and smaller than said first dimension,
said first retaining member having first and second notches therein,
said first and second notches extending along said first dimension
from an inner part of said first retaining member in opposed directions
transverse to said first direction and outwardly toward respective
outer surfaces of said first retaining member, and first and second
guide surfaces oblique to said first direction adjacent each of
said first and second notches, said first guide surface connecting
an upper portion of a respective one of said first and second notches
to said outer surface and said second guide surface connecting a
lower portion of a respective one of said first and second notches
to said outer surface, said guide surfaces cooperating to secure
a single convolution of said heater coil in each of said first and
second notches when said coil is at operating and non-operating
temperatures and to allow easy insertion of a convolution into each
of said first and second notches.
2. The electric heater of claim 1 wherein said two guide surfaces
diverge from said notch toward said outer surface.
3. The electric heater of claim 2 wherein said upper portion of
said notch includes a flat surface normal to said first direction
and wherein one of said guide surfaces intersects said flat surface.
4. The electric heater of claim 1 or 3 wherein said means for attaching
two elongate rods, for supporting said body, at least one of said
rods having a portion for being received by a groove in said body,
said two rods being secured together to create a band which encircles
5. An assembly as in claim 1 or 3 wherein
said means for attaching further comprises:
an elongate rod having at least one bent portion which at least
partially encircles said body and is received by a groove in said
6. An assembly as in claim 5 wherein said base comprises a plurality
of elongate side members, and wherein said means for attaching extends
between said side members.
7. An assembly as in claim 5 wherein said base comprises a single
8. The electric heater of claim 1 or 3 wherein said body portion
is a rectangular parallelepiped and said first retaining member
has a hexagonal cross-section with four equal sides and two facing
shorter sides in said transverse plane.
9. The electric heater of claim 1 or 3 wherein said retaining member
is narrower at said outer surfaces which are spaced in a direction
transverse to said first direction than at a central portion.
10. The electric heater of claim 9 wherein said notches receive
only a single convolution of said heater coil.
11. The electric heater of claim 1 or 3 further comprising a second
retaining member extending from said body portion in a second direction
opposite to said first direction, said second retaining member having
a first extent and a second extent, in a plane transverse to said
second direction, said first extent being greater than the spacing
between adjacent convolutions of said heater coil and said second
extent being transverse to and less than said first extent, said
second retaining member having third and fourth notches therein,
said third and fourth notches extending along said first extent
from an inner part of said second retaining member in opposed directions
transverse to said second direction and outwardly toward respective
outer surfaces of said second retaining member, and third and fourth
guide surfaces oblique to said second direction adjacent each of
said third and fourth notches, said third guide surface connecting
a lower portion of a respective one of said third and fourth notches
to said outer surface and said fourth guide surface connecting an
upper portion of a respective one of said third and fourth notches
to said outer surface, said third and fourth guide surfaces cooperating
to secure a single convolution of said heater coil in each of said
third and fourth notches when said coil is at operating and non-operating
temperatures and to allow easy insertion of a convolution into each
of said third and fourth notches.
12. The electric heater of claim 11 wherein said body is a rectangular
parallelepiped and each of said first and second retaining members
has a hexagonal cross-section with four equal sides and two facing
shorter sides in said transverse plane.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to electric heaters, and more particularly
to such heaters utilizing support insulators for retaining and securing
electric heater coils therein.
2. Description of the Prior Art
Electric heaters, utilizing resistance wire supported in a frame
are known in the art. Such heaters, typically called open-coil heaters,
require the use of insulators to separate the resistance wire from
the frame structure and to avoid the possibility of a short circuit
between the resistance wire and the frame. Heaters of this type
similarly require the use of means for retaining the resistance
wire in a predetermined, desired configuration with respect to the
Prior art devices are known which attempt to provide insulators
including coil holders for retaining a heater coil and insulating
the same from the heater framework. Wightman et al., U.S. Pat. No.
3,846,619 discloses the use of insulator means mounted on cross
beams of a heater frame for supporting a helical heater wire. Clip
means are required to be attached to the insulators, however, in
order to properly support the heater coil. The clips need to be
specially formed with flange surfaces bent in non-planar configurations
to retain the heater wire. Moreover, insertion of a convolution
of the coil within the clip is made difficult, and removal of the
coil, which might be required for maintenance or repair, is extremely
difficult. The cross beams of the framework require a particular
structure, and incorporate tabs to interact with portions of the
insulator body to retain the insulator therein. Similarly, tabs
are required on the clip means to secure the same on the insulators.
In summary, a structure is disclosed in the reference, requiring
a number of complicated steps eliminated by the present invention.
Specifically, the presently disclosed structure embodies a unified
insulator support which may be easily mounted in the cross beams
of a frame. The mounting process utilizes a first set of notches
in the insulator structure, while the coil is secured by a second
set of notches. Tabs are not required, and assembly of the device
Simmons, U.S. Pat. No. 1,698,282, similarly discloses an electric
heater incorporating insulators, or supports, which require special
manipulation for mounting on the cross beams. Additionally, each
support structure requires the use of two insulator elements. Simultaneous
manipulation of the two elements is required in a 90.degree. rotation
for mounting the support structure, and a complicated manipulation
of several combined support structures is required for the removal
of a single damaged support. Moreover, the use of cotter pins is
mandated in order to secure the supports against displacement. Unlike
the Wightman et al. disclosure, the supports in Simmons cannot protrude
through the cross beams, and thus may support a heater coil on only
one side of the frame.
Hartman, U.S. Pat. No. 2,856,500, discloses a single integral insulator
for an electrical heater which is mounted to a reflector in the
heater. The reflector includes a plurality of key openings for receiving
key-like projections from the insulator. The projections are narrower
than the body of the insulator, and disposed on opposite sides of
the body with respect to the heater coil support means. Accordingly,
the possibility of providing a single support structure capable
of supporting electric wire on both sides of a support beam is precluded
by the disclosed structure. As in Wightman et al., tabs are required
to be manufactured in the support beams for the insulators, and
as in Simmons, special rotational steps are needed for mounting
the insulators on the heater reflector.
Other teachings of insulators and spacers used in conjunction with
electric heaters include McKeown U.S. Pat. No. 2,177,930; Gasparaitis,
U.S. Pat. No. 3,632,981 and Laing, U.S. Pat. No. 3,218,437. Weimar,
U.S. Pat. No. 1,712,860 discloses the use of two insulators above
and below a cross arm of a telephone, electric or telegraph pole,
the insulators having an annular groove for the wire.
It is accordingly seen that none of the prior art references disclose,
either singly or in combination, an easily fabricated, easily assembled
and simplified structure for supporting resistance wire in electric
heaters. The present invention provides an insulated supporter,
for an electric heater, which is integrally formed and is substantially
symmetric. These features permit insertion of the insulator within
the support beam structure of an electric heater with a terminal
orienting and aligning effort, and further permit straightforward
assembly of the heater wire to the frame by simplified attachment
to the insulator.
Mounting of the insulators to the support beams is accomplished
by insertion into a cavity, a snapping or clipping action taking
place between the beam structure and notches on the insulators.
A second set of notches provides a similar snap-fit for the resistance
heater wire mounted on the support insulators.
SUMMARY AND OBJECTS OF THE INVENTION
The present invention overcomes the deficiencies of the prior art
and provides an electric heater having a framework for supporting
a resistance heater wire, the framework including support beams
for a plurality of support insulators. The support beams may be
comprised of one or more metal rods, the rod or rods being bent
at predetermined locations to form cavities for accepting the insulators.
The insulators of the present invention are inserted into the cavities
and locked in place by the rods which fit a pair of notches on each
insulator. A second set of notches, substantially coplanar with
the first set, accepts at least a single convolution of the helical
heater wire. The heater wire is retained in place by the spring
action of its coils and the width of the ceramic shoulders, acting
in cooperation with the second set of notches. The pair of shoulders
on the insulators extend beyond the coil convolution to prevent
transverse movement of the coil, while axial displacement is prevented
by the body of the insulator.
It is accordingly an object of the invention to provide an easily
manufactured electric heater having an open heater coil structure.
It is another object of the invention to provide an easily fabricated
support insulator for use in an electric heater.
It is still another object of the invention to provide an electric
heater having a longitudinal frame with transverse cross beams,
wherein the cross beams are easily manufactured.
It is yet another object of the invention to provide an electric
heater having support insulators insertable into cavities within
support beams of its framework, the cavities having a shape matching
the cross section of the insulators and preventing rotational movement
of the insulators therein.
It is an additional object of the invention to provide an electric
heater wherein support insulators are inserted in cavities formed
in support beams, the depth of insertion being determined by cooperation
between the support beam structure and support insulator structure.
A further object of the present invention is to provide a support
beam for retaining the insulators in place by a clipping action.
Still a further object of the invention is the provision of integrated
support insulators for an electric heater, the insulators having
first and second mounting means therein, the first and second mounting
means comprising notches situated substantially in a single plane.
Yet another object of the invention is the provision of integrated
support insulators for an electric heater, the insulators having
a first set of notches for mounting to a support beam of said heater,
a second set of notches for accepting and retaining a heater wire
disposed on one side of the support beam, and a third set of notches
for accepting and retaining a heater wire disposed adjacent the
opposite side of the support beam.
The present invention also provides an electric heater having a
framework for supporting a resistance heater wire, the framework
including a longitudinal elongated structural member supporting
a plurality of gripping members securing support insulators. The
support insulators preferably have a first pair of notches oppositely
disposed on either longitudinal end of the insulator with the gripping
member having a first and second portion releasably fitting in the
notches of the support insulators. The gripping member preferably
grips a pair of support insulators and is attached to the elongated
structural member with the insulators symmetrically disposed about
the elongated structural member. A second set of notches, substantially
coplanar with the first set, accepts a single convolution in the
helical heater wire. The heater wire is retained in place by the
spring action of the coils, acting in cooperation with the second
set of notches. A pair of shoulders bordering the second set of
notches on the support insulators extends beyond the coil convolution
to prevent transverse movement of the coil, while axial displacement
is prevented by the body of the insulator.
These and other objects, features and advantages of the present
invention will become apparent from the following specification
and appended claims when considered in conjunction with the attached
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a perspective view of an electric heater embodying the
FIG. 2 is an elevational view of the electric heater of FIG. 1
taken along line 2--2 therein;
FIG. 3 is a fragmentary plan view of the heater of FIG. 2 taken
along line 3--3 therein;
FIG. 4 is an elevational view of a support insulator of the present
invention as used in the heater of FIG. 2 and viewed along line
FIG. 5 is an edge view of the support insulator of the invention
as used in the heater of FIG. 4, taken along line 5--5 therein;
FIG. 6 is a perspective view of a support insulator in accordance
with the present invention;
FIG. 7 is a plan view of a support insulator of the present invention;
FIG. 8 is an elevational view of a support insulator of the present
FIG. 9 is a plan view of an electric heater containing a second
embodiment of the present invention;
FIG. 10 is a side elevation of an electric heater containing the
second embodiment of the present invention;
FIG. 11 is a plan view of the support insulators of the second
embodiment of the present invention;
FIG. 12 is an end view of the support insulators of the second
embodiment of the present invention; and
FIG. 13 is a plan view of the gripping member in the second embodiment
of the invention seen in the process of bending.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to FIG. 1, a first embodiment of an electric heater
incorporating the present invention is generally shown at 10. As
is seen in the figure, the heater includes a frame 12, the frame
including leg supports 14 and 16 for spacing the heater from a horizontal
support surface (not shown) upon which it may rest. The frame further
includes structural members 18, shown as elongated beams connecting
side members 20 and 22 of the frame.
The first embodiment of the present invention utilizes an electrical
resistance heater wire, shown at 24, coiled along an axis as is
known in the art. The heater coil includes a plurality of convolutions,
typically forming a helical structure, providing a spring-like appearance
to the wire and adding a spring-like resilience to the wire in the
axial direction of the coil. The heater coil must be spaced apart
from the frame members, including beams 18, to avoid the occurrence
of electrical short circuits. The longitudinal axis of the coil
is preferably oriented transversely to the structural members 18
to avoid interference by members 18 with the heat radiation pattern
of the coil as well as to provide support for a maximal heater area
with a minimal number of structural members 18.
The heater coil may comprise two segments 26 and 28, above and
below the plane of structural beam members 18 respectively. The
segments may both be portions of the same coil, as shown in FIG.
1, or may be two distinct and separate coils.
The present heater is shown as including a faceplate structure
30, which includes therein a means 32 for providing electrical current
to the heater coil. The faceplate and electrical contact are shown
connected to frame 12 by a connecting means 33. It is appreciated
that the entire assembly may be enclosed in an enclosure, and that
faceplate 30 and contact means 32 may be part of that enclosure.
In order to provide support for heater coil 24, and to space the
same from frame 12, a plurality of insulated support means 34 are
provided. As seen in FIG. 1, support means 34 are mounted on structural
members 18. It is within the scope of the invention, however, to
mount insulated support means 34 on various portions of frame 12.
Such mounting may require a modification of the frame members, however,
to conform with the features of structural members 18 as described
in the sequel. In the event that the frame 12 is comprised of materials
having dimensions differing from those of structural beams 18, it
might be necessary to provide two sets of insulated supporters.
Both sets are formed in accordance with the present invention, but
have different dimensions to cooperate with the different dimensions
of the frame and the structural beams. It is also possible, of course,
that a single insulated support means may be mounted on each structural
beam although three supporters are shown in the figures.
In accordance with the invention, structural members 18 may be
formed of rods 36 and 38 as shown in FIGS. 3 and 4. As best seen
in FIG. 3, the rods are bent and joined together, the bends in each
rod being aligned with the other to form a cavity having a predetermined
peripheral configuration for receiving support means 34. While both
rods 36 and 38 are shown in the Figure as having bent portions 37
and 39, it is recognized that one rod may be straight and only one
rod bent, and that a cavity may be formed by joining the straight
and the bent rods together. Structural beams formed of two identical
rods, each having bent portions, require no sorting of the rods,
however, thus simplifying manufacture of the heater. That is, structural
beams formed as shown in FIG. 3 utilize pairs of identifical rods,
while beams formed of straight and bent rods require a sorting step
in their fabrication to separate the dissimilar rods. It is seen
that greater economy of manufacture is achieved by using the preferred
structure of FIG. 3.
As shown in FIGS. 1-4, support insulators 34 are received in openings
formed in beams 18. It is possible, of course, that the beams may
be manufactured from components other than as shown in FIGS. 3-5,
and that cavities be provided therein otherwise than as previously
Referring specifically to FIGS. 4-8, it is seen that insulated
receiving support means 34 include a central body portion 40 having
first mounting means comprising notches 42 and 44 formed therein.
These notches are used to mate with rods 36 and 38, as shown in
FIG. 4, thereby locking the insulators in place. Specifically, the
largest cross sectional area of supporter 34, formed in central
body 49 thereof, exceeds the area of the predetermined peripheral
configuration formed by bent portions 37 and 39 of rods 36 and 38.
The rods, or other components of beams 18, are thus caused to flex
and expand slightly to accommodate the central body portion 40 during
insertion of supporter 34 in the beam. The general shapes of the
cavity periphery and of the cross section of supporter 34 are similar,
in order to avoid the necessity for complete misshaping of the beam
during insertion of the supports. When insertion has proceeded to
the point of contact between rods 36 and 38 and notches 42 and 44
formed in the insulator support, the rods spring back to their original
forms and mate with the notches, thus mounting the insulators on
the beams. Two notches are shown in central body portion 40 for
providing a tighter retention of the insulator by the beam. However,
a single notch may similarly be used, at the cost of reduced retention
force. Alternatively, three of four notches may also be used. Further
still, the two notches shown in the shorter dimensioned parallel
and oppositely disposed, longitudinally transverse sides 46 and
48 may be provided in the substantially flat front and back faces
of the structure, the front face being shown at 49, having a longer
dimension than the side faces.
As shown in FIG. 6, the insulated supporter of the present invention
includes upper and lower coil retainers, the second mounting means,
at opposite sides of the supporter, labeled 50 and 52, respectively.
It is within the scope of the invention to provide insulated support
means having a single coil retainer, either 50 or 52, for supporting
a heater coil on only one side of the plane formed by beam structure
18. The preferred embodiment, however, incorporates two coil retainers
as shown. As is seen in the figures, the insulated supporters of
the present invention are completely symmetrical. That is, the supporters
may be rotated about a horizontal axis of symmetry without alteration
of their appearance. A similar observation may be made with respect
to a vertical axis of symmetry, inasmuch as the number of orientation
steps which must be performed, prior to proper insertion of a supporter
in a cavity formed within the beams, is minimized thereby. Assembly
may proceed after a single orientation step, in which it is determined
that the width dimension of front face 49 of the insulator is transverse
to the longitudinal dimension of a structural beam.
In view of the above described symmetry, the following description
of the upper coil retaner 50 is not repeated for lower retainer
52. The upper retainer 50 is provided with a flat surface 54, permitting
fabrication of a plurality of end-to-end connected insulators which
may be severed along mating flat surfaces 54. Surface 54 may be
provided with a peaked portion and with slanted surfaces sloping
downwardly towards the front face 56 of the upper retainer 50. Such
slanted surfaces may be used to ease insertion of the supporters
into the cavities in beams 18. As is seen in the figures, however,
the front face 56 is backwardly slanted from a peak 57 substantially
at its center, thereby providing substantially narrower surfaces
at sides 70 and 72 than at the peak 57. An advantage of the narrow
sides 70 and 72 is the ease of insertion of the corners or the coil
retainers into the cavities in beams 18, and the ability of prying
open the cavities to accommodate the remaining portion of the insulator.
Similarly, as the notches form a first mounting means in central
body 40 of the supporter, one or more notches are formed in upper
coil holder 50. Notches 58 and 60 form a first set of notches in
the insulated supporter, for retaining a heating coil above the
plane of structural members 18. A second set of notches, shown at
59 and 61, is formed in lower coil retainer 54. Notches 59, 61 form
a second mounting means.
In an alternative embodiment of the invention, support means 34
has sides 70 and 72 flush with the longitudinal ends of body portion
40. This would simplify the construction of support means 34 by
eliminating side 72.
The notches forming the second mounting means are essentially parallel
to the notches forming the first mounting means. Such a relationship
between the notches eases fabrication of the supports. Guide means,
comprising inclined surfaces 62 and 64, urge the portions of a single
convolution 25, shown in FIG. 4, toward notch 58. Similar inclined
surfaces 66 and 68 provide a guide means leading the coil towards
notch 60. Other guiding surfaces are also provided for the lower
coil retainer 52. Such inclination permits the spring-like flexibility
of the heater coil to cause the turns thereof gently to return to
the mounting notches in the event of a displacement therefrom. Longer
horizontal portions may be provided within the notches, thus providing
a more positive locking of the coil in place once inserted.
As seen further in FIG. 4, vertical side surface 70, in cooperation
with inclined surface 62, forms a shoulder portion which retains
coil 26 and prevents vertical transverse displacement thereof. The
presence of coil retainer 50 between the portions of convolution
25 is seen to prevent longitudinal displacement of the heater coil.
As described herein, the present invention accordingly provides
an insulated support means for retaining a heater coil in place.
The support means are easily fabricated, preferably in intergrated
form, and readily assembled in a heater structure utilizing a simplified
The second embodiment of the invention disclosed herein can be
seen in FIGS. 9-13. FIG. 9 shows a partial plan view of the structure
of the second embodiment of the invention and FIG. 10 shows a partial
side elevational view of the second embodiment of the invention.
FIG. 9 shows a frame comprising a face plate structure 101 and a
longitudinal elongated structural member 103. Means for producing
electric current 107 are held in place in the face plate structure
101. A heater coil 24, hereafter electric resistance heater wire
24, is held in place along the heater and connected to means for
producing electric current 107 and is supported in position by support
insulators 34. Gripping means 105 holds the support insulators 34
symmetrically about the longitudinal, elongated structural member
103. The support insulators 34 support the singular electrical resistance
wire 24 which loops around elongated structural member 103 and is
connected on each end to a means for providing electrical current
A closeup plan view of the gripping means 105 holding support insulators
34 can be seen in FIG. 11. In FIG. 11, the gripping means 105 comprises
a singular piece of wire bent to substantially surround support
insulators 34 having a transverse leg 109, longitudinal leg 111
and a transverse leg 113 substantially surrounding support insulator
34 with leg 109 receivably accepted in notch 42 and leg 113 accepted
in notch 44 of support insulator 34. A second longitudinal leg 115
abuts against the body portion of support means 34 oppositely disposed
from longitudinal leg 111 to substantially surround support means
34 with the gripping means 105. Bridge member 117 transversely crosses
and is connected to longitudinal structure member 103 and secures
gripping member 105 in place. Notches 58-61 function to support
electrical resistance heater wire 24 by capturing adjacent loops
of a coil as described above. A front elevation of support insulators
34 held in gripping means 105 can be seen in FIG. 12.
FIG. 13 shows a view of a partially bent gripping member 105 during
manufacture where it can be seen that legs 109, 113, 115 and bridge
members 117 are bent around a jig to proper shape. Insulator 34
is then placed with notch 42 butting against leg 113; leg 111 is
then bent around insulators 34, and leg 109 is accepted in notch
44 to securely hold the insulator 34 in place.
The preferred embodiments of the invention hereinabove described
are provided as illustrations, and not as limitations, of the invention.
Equivalent variations of the described embodiments will occur to
those skilled in the art. Such modifications, variations and equivalents
are within the scope of the invention as recited with greater particularity
in the following claims, when interpreted to obtain the benefits
of all equivalents to which the invention is fairly entitled.