Abstrict
An electric heater construction which significantly reduced the
possibility of electrical shock to a user thereof. This electric
heater includes an outer casing with an open front, a protective
grille mounted over the open front of the outer casing, a reflector
assembly mounted within the outer casing and a heating element enclosure
mounted to the reflector assembly such that it is electrically insulated
therefrom. A ribbon-type of heating element is mounted within the
heating element enclosure. If any portion of the heating element
should break or for any other reason become disengaged from the
insulated mounted structure, the heating element enclosure effectively
prevents it from coming in contact with any non-insulated portion
of the device which is readily accessible to a user of the heater
thereby protecting a user of the device from electrical shock.
Claims
Having thus described the invention, we claim:
1. In an electric heater having an outer casing with an open front,
the improvement comprising:
a protective grille attached to the outer casing and covering a
substantial portion of said open front;
a reflector mounted within the casing;
a heating element enclosure having a perforated face;
means for mounting said heating element enclosure within an operative
proximity of said reflector and for electrically insulating said
enclosure from said reflector and for preventing said heating element
from contacting said reflector in the event said heating element
becomes broken, disengaged or abnormally deflects, the apertured
face of said heating element enclosure outwardly facing the open
front of said outer housing; and
a ribbon-type heating element mounted within said heating element
enclosure and electrically insulated from said casing said enclosure
having substantially the entire heating element mounted therein.
2. An electric heater as in claim 1 including means for spring
biasing said heating element.
3. The electric heater as in claim 1 wherein said heating element
enclosure comprised of:
a reflective rear wall,
means for mounting said apertured face in a spaced apart relationship
with respect to said reflective rear wall.
4. The combination as in claim 3 including means for urging said
heating element to a taut condition.
5. The combination as in claim 3 wherein said enclosure has at
least a portion thereof that is movable with respect to said reflector,
said movable portion carrying said heating element mounted thereon
and operable to permit expansion or contraction of said element.
6. An electric heater as in claim 1 wherein said heating element
enclosure is comprised of:
a first end wall constructed of a non-conductive material, said
first end wall being fixedly mounted onto said reflector;
a second end wall movably coupled with said reflector such that
said second end wall is electrically insulated from said reflector,
said apertured face having apertures distributed over substantially
its entire outwardly facing area, said face being attached to said
second end wall and located between said heating element and said
protective grille; and
a bottom plate attached to said second end wall and located between
said heating element and said reflector.
7. An electric heater as in claim 6 including means for applying
a resilient force to said second end wall, said force operable to
urge said second end wall and said face away from said first end
wall.
8. The electric heater as in claim 6 wherein said heating element
is alternately strung between the first and second end walls of
said heating element enclosure in the sinuous configuration.
9. The electric heater as in claim 8 including means for resiliently
forcing said second end wall away from said first end wall to maintain
said heating element under tension.
10. The combination as in claim 6 including a second heating element
mounted within said enclosure, and means for urging said second
heating element to a taut condition.
11. The combination as in claim 7 wherein said second element urging
means includes a means for pivotally mounting said second element
to said second end wall.
12. An electric heater comprising:
an outer casing with an open front;
a protective grille attached to said outer casing and covering
said open front;
a reflector having an inner cavity formed by a rear surface and
being at least partially reflective and a plurality of side reflective
surfaces extending outwardly from the periphery of said rear surface,
said reflector being mounted within said outer casing such that
said inner cavity is adjacent to the open front of said outer casing;
a ribbon-type of heating element; and
means for mounting said heating element within the inner cavity
of said reflector and for preventing said heating element from contacting
said reflector in the event said heating element becomes broken,
disengaged from said mounting means or abnormally deflects, said
mounting means including a heating element enclosure which substantially
encloses the entire heating element therein, said enclosure being
mounted within the inner cavity of said reflector and further including
means for electrically insulating said enclosure from said reflector.
13. An electric heater as in claim 12 including tension means for
urging said heating element to a taut condition.
14. The combination as in claim 12 wherein said heating element
enclosure includes:
a first end wall constructed of a non-conductive material, said
first end wall being fixedly mounted onto said reflector;
a second end wall movably coupled with said reflector such that
said second end wall is electrically insulated from said reflector,
said apertured face having apertures distributed over substantially
its entire outwardly facing area, said face being attached to said
second end wall and located between said heating element and said
protective grille; and
a bottom plate attached to said second end wall and located between
said heating element and said reflector.
15. An electric heater as in claim 14 including means for applying
a resilient force to said second end wall, said force operable to
urge said second end wall and said face away from said first end
wall.
16. The electric heater as in claim 14 wherein said heating element
is alternately strung between the first and second end walls of
said heating element enclosure in the sinuous configuration.
17. The electric heater as in claim 16 including means for resiliently
forcing said second end wall away from said first end wall to maintain
said heating element under tension.
18. The combination as in claim 15 including a second heating element
mounted within said enclosure, and means for urging said second
heating element to a taut condition.
19. The combination as in claim 17 wherein said second element
urging means includes a means for pivotally mounting said second
element to said second end wall.
Description BACKGROUND AND BRIEF DESCRIPTION OF THE INVENTION
This invention relates in general to electric space heaters and,
in particular, to the improvement in such heaters which significantly
enhance the safety thereof.
Many different types of electrical heaters are disclosed in the
prior art. Most of these heaters, however, fall into two main categories.
The first group of electrical heaters comprises heaters in which
the heating element is helically wound around an insulated member
which may be positioned in front of a reflective surface. The heating
element and reflective surface (if used) are normally located within
an outer casing having an open front so that the heat generated
by the heating element is directed outward through the front of
the heating device. A protective grille is usually provided to cover
the open front of the outer casing.
In a second type of electrical heater, a ribbon type of heating
element is normally strung between insulators located at opposite
ends of a reflector assembly typically enclosed by an outer casing
having an open front through which the heat generated by the heating
element is directed. As in the above device, a protective grille
is used for covering the open front of the casing.
The heating element is normally strung between insulators on opposing
sides of the reflector assembly such that the element traverses
the reflective surface of the reflector assembly without any intermediate
means of support. To compensate for expansion and contraction of
the heating element during use, spring tension keeps same taut at
all times. If the heating element should break and deflect or merely
become disengaged from its mounting, it is possible for it to come
in contact with an electrically conductive portion of the heater
such as the outer casing, reflector assembly or protective grille.
These portions of the heater may be readily accessible to a user
of the heater, thereby offering the possibility of an electrical
shock.
The present invention overcomes this possibility by containing
the ribbon-like heating element within a heating element enclosure
which is electrically insulated from the conductive components of
the heating device. If the heating element should break, or inadvertently
deflect, the heating element enclosure prevents the current carrying
heating element from coming in contact with the heater's outer casing,
reflector assembly or protective grille. Accordingly, the heating
element enclosure serves to electrically isolate the heating element(s)
of the device from any component of the heater which is readily
accessible to a user thereof.
The heating element enclosure is comprised of a rectangularly shaped
structure having a perforated face, and is mounted to the reflector
assembly such that the perforated face of the structure faces toward
the open front of the heater's outer casing. The heating element
enclosure is electrically insulated from the reflector assembly
to electrically isolate the enclosure (and the heating elements)
from the remainder of the heating device and is spaced a sufficient
distance away from the protective grille within the housing to prevent
a user from intentionally or inadvertently contacting it.
It is therefore an object of the present invention to provide an
improved heater utilizing one or more ribbon-type heating elements
wherein the chance of electrical shock to a user in the event of
breakage of a heating element is significantly reduced.
A further object of the present invention is to provide an improved
heater utilizing a ribbon-type of heating element wherein the heating
element is contained within a heating element enclosure which is
electrically insulated from the external components of the device.
Another object of the present invention is to provide an improved
heater utilizing a ribbon-type of heating element wherein the heating
element is contained within a heating element enclosure which prevents
a broken or loose heating element from effecting electrification
of any portion of the heater that is readily accessible to a user
thereof.
Another object of the present invention is to provide an improved
heater having a heating element enclosure with a perforated face
which absorbs some of the radiant heat generated by the heating
element to lower the temperature at the opening (and grille) in
the outer casing of the heater.
Another object of the invention is to provide, in an improved heater
of the character described, a plurality of means for spring biasing
physically separated heating elements, said means being capable
of independent operation.
It is an additional object of the present invention to provide
a heater of the character described which is simple and economical
to construct.
Other and further objects of this invention, together with the
features of novelty appurtenant thereto, will appear in the course
of the following description.
DETAILED DESCRIPTION OF THE DRAWINGS
In the accompanying drawings which form a part of the specification
and are to be read in conjunction therewith and in which like reference
numerals are used to indicate like parts in the various views:
FIG. 1 is a front elevational view of a heater constructed according
to a preferred embodiment of the present invention, with portions
broken away for the purposes of illustration;
FIG. 2 is a cross sectional view on an enlarged scale taken generally
along lines 2--2 of FIG. 1 in the direction of the arrows with portions
broken away for the purposes of illustration;
FIG. 3 is a fragmentary sectional view taken generally along lines
3--3 of FIG. 2 in the direction of the arrows with portions broken
away for the purposes of illustration;
FIG. 4 is a sectional view taken along lines 4--4 of FIG. 3 in
the direction of the arrows; and
FIG. 5 is a sectional view taken along lines 5--5 of FIG. 3 in
the direction of the arrows.
Referring now to the drawings and initially to FIGS. 1 and 2, numeral
10 is used to generally designate a modular electric space heater
which is constructed in accordance with a preferred embodiment of
the present invention. The heater is constructed to have an outer
metallic casing 12. The outer casing is rectangular in shape and
is comprised of a back wall 14, a front wall 16, a bottom wall 18,
a top wall 20 and opposing side walls 22 and 24. An opening 26 is
provided in the front wall. This opening is in turn covered by a
protective grille 28 which is suitably secured to the front wall
of the outer casing. While the specific configuration of the grille
can take many different forms, the one shown herein is comprised
of a plurality of spaced vertical bars 30 which are secured as by
welding to a plurality of horizontal bars 32. The configuration
of the protective grille should be such that the space between the
bars permits air to readily pass therethrough unimpeded, but restricts
the passage of foreign objects such as fingers and the like.
The heater also includes a control compartment (designated by the
numeral 34 and directed to the front panel member thereof) wherein
the conventional components for operating the heater are contained.
These components include, for example, a temperature responsive
control switch operated by a knob 36 which is accessible from outside
the heater and a wattage control switch which is also accessible
from outside the heater by means of a switch device 38. A motor
driven fan and the conventional electrical wiring is also contained
within the control compartment.
The casing is supported by legs 40 which are secured to opposite
ends of the casing's bottom wall 18. These legs are provided with
cushioning feet 42 which rest on the floor or other support surface.
Referring now principally to FIGS. 2-5, a reflector assembly 44
is mounted within the inner casing of the heater. The reflector
assembly is comprised of a reflective surface which is constructed
from a piece of sheet metal to have an optional rear wall 46 and
a plurality of forwardly projecting side walls 48, 50, 52, and 54.
The rear (if used) and side walls of the reflective surface cooperate
to form a trapezoidal-shaped structure having a hollow inner cavity.
The reflective surface is in turn attached to the front wall of
the outer casing by means of a plurality of mounting screws 56.
The reflective surface is secured to the outer casing such that
the rear wall (or rear opening if the wall 46 is not used) of the
surface faces the opening in the front of the casing and such that
the hollow inner cavity of the reflector assembly 44 is adjacent
to this opening.
A pair of ribbon-like heating elements 58 and 60 are mounted within
the interior cavity of the reflector assembly. These heating elements
are contained within a heating element enclosure 62 which is suitably
mounted within the interior cavity of reflector assembly 44 such
that it is electrically insulated therefrom as will be described.
The heating element enclosure is comprised of a pair of opposing
end walls 64 and 66 (see FIG. 4). End wall 64 is constructed of
mica or some other type of nonconductive material which can be formed
into a rigid piece. This wall has a tab 68 (FIGS. 4 and 5) integrally
formed therewith. This tab in turn fits within a slot (not shown)
in the rear wall 46 of reflector assembly 44 to secure one edge
of end wall 64 to the reflector assembly 44. (If the rear wall 46
is eliminated, similar side wall mounting could be used). The other
end of end wall 64 is in turn secured to side wall 52 of the reflector
assembly by means of a mounting bracket 70. (Alternatively, tabs
may be formed up directly from side wall 52 of the reflector assembly
and be secured to end wall 64 by being inserted through slots and
bent over). One end of mounting bracket 70 is secured to end wall
64 by means of a plurality of rivets or by bent over tabs 72 while
the other end of this bracket is secured to side wall 52 of reflector
assembly 44 by means of a plurality of rivets or by tabs 74. End
wall 66, on the other hand, is comprised of a channel shaped bracket
having a base portion 76 and a pair of extending portions 78 and
80.
A face plate 82 is in turn attached to the extending portion 78
of end wall 66 by means of rivets or tabs 84 and located within
the confines of flange 86 (formed from a portion of end wall 64).
The length dimension of the plate 82, in conjunction with the later
described spring tension on the heating element limits the positioning
of plate 82 with respect to flange 86. With this mounting arrangement,
plate 82 is permitted to move laterally with end wall 66 as same
may move with the expansion or contraction of the heating elements.
The face plate is provided with a plurality of perforations (or
apertures) 88 which substantially covers the entire area thereof
and has a portion of each lateral side bent over so that it covers
at least a portion of its corresponding side of the enclosure. Each
of the above mentioned perforations is circular in shape, and of
a diameter smaller than the width of heating element 58 or heating
element 60. (Alternatively, the face plate 88 could be constructed
of a wire mesh with the apertures between the wires similarly sized
to the above mentioned perforations).
A back plate 90 (FIG. 4), normally having a reflective surface,
is attached to the extending portion 80 of end wall 66 by means
of rivets or tabs 92. A portion of each lateral side of the bottom
plate is bent out as described above with respect to the face plate
mount wherein the bent out portions of the bottom plate cooperate
with the bent over portions of the face plate to form the lateral
side walls of the heating element enclosure.
Heating element 58 is a ribbon-type of heating element which is
comprised of a single continuous strand of electrically conductive
material or a plurality of individual strands which are electrically
coupled with each other in series. This heating element (58) is
carried by a first group of non-conductive insulators 100 (conveniently
made of Steatite) which are mounted to end wall 66 of the heating
element enclosure, a second group of non-conductive insulators 102
extend through a slot in end wall 64 and are mounted on the side
wall 54 of reflector 44, and a pair of non-conductive insulators
104 an 106 which are mounted to side wall 54 of the reflector assembly
and serve to anchor the heating element.
As mentioned above, one end of the heating element is anchored
by insulator 104. From insulator 104, the heating element enters
the heating element enclosure through a slot (not shown) in end
wall 64. Within the heating element enclosure, the heating element
is alternately strung between the insulators of the first and second
groups such that the heating element traverses the back plate 90
of the heating element enclosure without any intermediate means
of support. Heating element 58 exits the heating element enclosure
through a second slot (not shown) in end wall 64 and has its other
end anchored by insulator 106. A pair of conductor lines 108 and
110 are electrically coupled with the opposite ends of the heating
element at insulators 104 and 106, respectively. These conductor
lines are used to supply electrical current to the heating element.
Heating element 60, also a ribbon-type of heating element, preferably
is formed by a single continuous strand of metal. One end of this
heating element (60) is terminated and supported by a non-conductive
insulator 112 while the other end of this heating element is terminated
and supported by a second non-conductive insulator 114. Both of
these insulators are mounted in the side wall 54 of the reflector
assembly. From insulator 112, the heating element enters the heating
element enclosure through an opening (not shown) in end wall 64
of the heating element enclosure. Heating element 60 then passes
around a second set of two non-conductive insulators 116 and 118
which are also constructed to have a pulley-like configuration.
The heating element than traverses the back plate 90 of the heating
element enclosure, is spaced forwardly of element 58, and exits
the heating element enclosure through an opening (not shown) in
the end wall 64 of the enclosure before being terminated and supported
by insulator 114 on side wall 54.
Insulators 116 and 118 are in turn mounted to end wall 66 of the
heating element enclosure by means of mounting bracket 120 and 122,
respectively. Mounting bracket 120 is a U-shaped bracket having
intermediate portion 124 separating two extending arms 126 and 128.
A mounting flange 130 projects outward from the top of extending
arm 128 at a right angle therewith. Extending arm 126 of the bracket
is received by an opening in insulator 116 to thereby mount this
insulator in place on the mounting bracket. The insulator is secured
in place on arm portion 126 by two tabs extending from arm 126 through
insulator 116. The tabs may then be bent over to fixedly locate
the insulator. The bracket (120) is in turn mounted to end wall
66 of the heating enclosure by passing mounting flange 130 through
a corresponding slot in the end wall such that a portion of this
arm projects past the end wall. Once mounting flange 130 has been
positioned within its corresponding slot, the upper portion of the
arm which extends past the end wall 66 is bent over to retain the
bracket in place on the wall. However, flange 130 is appropriately
bent to permit it to pivot about its mounting slot in the direction
necessary to accommodate expansion and contraction of heating element
60. Insulator 118 is mounted to end wall 66 in the same manner by
mounting bracket 122 which is constructed to have the same configuration
as mounting bracket 120.
A spring 132 is attached to the portion of each bracket which extends
beyond end wall 66. This spring operates to force insulators 116
and 118 away from each other and serves to provide a means for effectively
compensating for expansion and contraction of the heating element
during use.
A conductor line (134 and 136) is attached to each end of heating
element 60 at insulators 112 and 114, respectively. These electrical
conductor lines are operable to provide electrical current to this
heating element.
To compensate for the natural expansion and contraction of heating
element 58 during use, the heating element is maintained under constant
tension to keep it taut at all times. The heating element is maintained
under tension by resiliently coupling the end wall 66 of the heating
element enclosure to the side wall 52 of the reflector assembly.
To accomplish this coupling, end wall 66 is attached to a mounting
plate 135 such that it is electrically insulated therefrom.
One technique for attaching the end wall 66 to mounting plate 135
is shown herein. In particular, a strip of non-conductive material
137 (such as mica or the like) is interposed between end wall 66
and mounting plate 135 at each end of the end wall. As shown in
FIG. 4, each strip of non-conductive material extends past the rear
edge of the end wall 66 a sufficient distance to keep the wall or
any part of the heating element enclosure from coming in contact
with the reflector assembly. Both strips of non-conductive material
are secured to end wall 66 by rivets 138 and to mounting plate 135
by rivets 140. In this manner the rivets (138) are not allowed to
come in contact with any part of the mounting plate 135 and the
rivets 140 which are to be used to secure each strip of insulating
material to the mounting plate 135 are not allowed to come in contact
with any part of end wall 66. Accordingly, end wall 66 is electrically
isolated from the mounting plate and from any part of the reflector
assembly.
Mounting plate 135 is provided with a pair of mounting arms 142
and 144. These arms are formed from "cutout" portions
of mounting plate 135, which extend outwardly therefrom at a right
angle with the face of the mounting plate 135. Each mounting arm
(142 and 144) in turn passes through a corresponding slot (not shown
herein) in side wall 62 of the reflector assembly such that a portion
of each arm extends beyond the outer surface thereof. A compression
spring 146 is then placed over the outwardly extending portion of
each mounting arm. A locking pin 148 is used to secure the spring
in place on the mounting arm. In this manner, the compression springs
impart a resilient force to end wall 66 of the heating element enclosure
which pulls the wall away from opposing wall 64 of the heating element
enclosure thereby keeping the heating element taut at all times.
In operation, an electric current is supplied to heating elements
58 and 60 by means of conductor lines 108, 110 and 134, 136 respectively.
Accordingly, these resistance type heating elements may be used
to generate radiant heat in the conventional manner. The heat thus
generated is directed outward through the open front of the heater
by means of the reflector assembly and the reflective surface of
back plate 90. It should be noted that the perforated face plate
82 blocks a portion of the radiant energy generated by the heat
elements. This in turn causes plate 82 to act as a converter which
changes a portion of the radiant into convective heat for eventual
dispersal into a room or space.
The above mentioned fan assists in creating air flow past plate
82 for improved heat transfer outwardly therefrom. It should be
noted that optional rear wall 46 of reflector 44, is provided with
suitable openings to allow airflow from the fan. Likewise plate
82 does block or screen a portion of the heating element(s) from
directly radiating heat to the front of the heater. In this manner
excessive radiant heat transfer is minimized to heat absorbing bodies
which may become overheated due to close proximity to the front
of the heater.
It is contemplated that suitable controls be used to cause either
both elements 58 and 60 to be simultaneously energized or only element
58 to be energized. This will afford wattage alternatives during
normal use of the heater. Likewise additional elements may be added
which may or may not be energized, affording many wattage alternative
possibilities.
If either heating element should break or become disengaged from
its mounting means, the heating element enclosure 62 prevents same
from coming in contact and electrifying any portion of the heater
which is readily accessible to a user thereof. Even if a broken
heating element comes in contact with any portion of the heating
element enclosure, the remainder of the heater is electrically isolated.
As a result, the heater of the present invention serves to significantly
eliminate any chance of electrical shock to the user of the device
as a result of breakage, deflection or disengagement of the heating
element(s).
Also, the present invention serves to significantly reduce chance
of electrical shock to the user of the device as a result of the
user accidentally or intentionally inserting some conductive material
through the grille, in the direction of the heating elements due
to the presence of the heating element enclosure which would serve
as an additional barrier and deterrent to any such inserted item.
From the foregoing, it will be seen that this invention is one
well adapted to attain all ends and objects herein above set forth
together with the other advantages which are obvious and which are
inherent to the structure.
It will be understood that certain features and subcombinations
are of utility and may be employed without reference to other features
and subcombinations.
As many possible embodiments may be made of the invention without
departing from the scope thereof, it is to be understood that all
matter herein set forth or shown in the accompanying drawings is
to be interpreted as illustrative and not in a limiting sense.
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