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Патент USA US3024355

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March 6, 1962
L. c. HANSON
3,024,345
ELECTRIC HEATING UNIT
Filed March 24, 1960
2 Sheets-Sheet 1
IiVVENTOR.
“Iggy 6.’, 170223022
March 6, 1962
|_. c. HANSON
3,024,345
ELECTRIC HEATING UNIT
Filed March 24, 1960
2 Sheets-Sheet 2
I
United States Patent Q??ce
1
3,024,345
Patented Mar. 6, 1962
2
3,024,345
permanently secured to the frame or spider and the coils
and have suitable shape and inherent resiliency to ac
commodate themselves to the contraction and expansion
of the coils which occurs in the temperature changes to
ELECTRIC HEATING UNIT
Leroy C. Hanson, Elmhurst, Ill., assignor to Ferro Cor
poration, Cleveland, Ohio, a corporation of Ohio
Filed Mar. 24, 1960, Ser. No. 17,332
which the heating unit is subjected.
The principal objects of the invention are to provide
8 Claims. (Cl. 219-37)
This invention relates to tubular sheathed electrical
an improved tubular sheathed heating unit of surface
heating units of the type adapted for range surface heat
heating type having a winding attached to a frame or
ing and has reference more particularly to the facilities
spider; to provide an improved attachment of the winding
by which the tubular sheathed elements thereof are at 10 to the spider; to simplify and facilitate the fastening of
tached to an underlying supporting frame or spider, this
the winding to the frame or spider; to insure certainty
application being a continuation in part of my pending
and permanence of the attachment of the winding to the
application Serial No. 662,041, ?led May 26, 1957, now
frame or spider with su?icient freedom of movement of
abandoned.
the coils of the winding on the spider for expansion and
In such heating units the tubular sheathed elements
contraction of the coils under temperature changes to
thereof are usually arranged in the form of a ?at wind
which they are subjected; and to accomplish the free
ing which is set in an opening of the range cooking top
dom of relative movement by the shape and resiliency
or in the opening of a mounting ring with the top face
of the fastener itself without special or complicated con
struction of the parts to which the fastener is attached
of the winding elevated slightly above the surrounding
' surface so that a cooking utensil will rest directly on the
winding, and it is customary to provide a pan under
neath the winding which serves not only to collect spill- ‘
_age but also as a re?ector to direct heat upwardly to
the bottom of the pan or utensil on the winding. This
pan or re?ector may be made as a part of the range top 25
or of the mounting ring but generally is a separate part
which may be removed for cleaning.
or tedious assembly procedure, these and other objects
being accomplised as pointed out more particularly here
inafter and as shown in the accompanying drawings, in
which:
FIG. 1 is a plan view of a heating unit assembly show
ing coil fasteners of this invention in single bend form;
FIG. 2 is an enlarged sectional view taken on the line
2-2 of FIG. 1 showing one of the coil fasteners;
FIG. 3 is a sectional view taken on the line 3-3 of
For supporting the coils of the winding above the
pan, an open frame or spider is employed which permits
FIG. 2;
spillage therethrough into the pan and also permits air
circulation therethrough to the coils, and the frame or
spider is commonly attached to the winding, and it is
FIG. 4 is a plan view of another form of heating unit
assembly employing coil fasteners of this invention of
multiple bend form;
customary to mount the winding and attached frame or
FIG. 5 is an enlarged sectional view taken on the line
spider in the opening of the range cooking top or mount
5-5 of FIG. 4;
ing ring so that it may be lifted up to provide access to 35
FIG. 6 is a sectional view taken on the line 6-6
the pan and to the frame or spider and the underside
of FIG. 5 ;
of the winding for cleaning thereof.
FIG. 7 is a view similar to that of FIG. 5 but show
Various expedients have been employed to permit ac
ing a modi?ed double form of the fastener of FIG. 5;
cess to the pan and the underside of the heating unit
FIG. 8 is a sectional view taken on the line 8—8 of
for cleaning thereof, the heating unit being sometimes
40
FIG. 7;
arranged for complete removal for this purpose, but gen
FIG. 9 is a view similar to FIG. 5 but showing an
erally it is preferred to hinge the heating unit at one
other form of the fastener of this invention;
side of the opening of the range top or ring so that it
FIG. 10 is a sectional view taken on the line 10—10
tilts to an upraised position at one side of the range top
of FIG. 9;
or ring opening to permit convenient access for cleaning
FIG. 11 is a view similar to that of FIG. 9 but show
or removal of the pan and for cleaning the underside 45 ing a modified double form of the fastener of FIG. 9;
of the heating unit itself.
FIG. 12 is a fragmentary sectional view of a marginal
In such heating units the end portions of the tubular
portion
of a heating unit assembly showing another form
sheathed elements of the winding are usually bent down
of fastener of this invention of a multiple bend form;
wardly to a suitable level below the plane of the winding
and
and extended outwardly through the side wall of the
FIG. 13 is a sectional view taken on the line 13—13
ring or pan so that they terminate at a protected place
' of FIG. 12.
underneath the range top for connection of current sup
For illustrative purposes, the invention is shown herein
ply conductors to terminal Wires which project from the
as embodied in a heating unit and mounting ring assem
ends of the tubular sheathed elements, and it is important
bly 20 of a generally conventional type which is adapted
that the place of connection of the current supply con
to be mounted in an opening in the cooking top of an
ductors with these terminal wires be arranged so as to
electric range in the usual manner.
be safeguarded against access of spillage or grease there
to as such spillage or grease at the terminal ends may
cause current leakage or shorts to occur at the terminals
or it may even migrate into the end of the tubular sheath
and cause current leakage or shorts therein.
Because of the expansion and contraction of the coils
of the winding on account of extreme temperature
changes, it is important that the coils of the winding be
The assembly 20 comprises a mounting ring 21 hav
ing a supporting spider member 22 pivoted or hinged at
one side of the mounting ring, and arranged to carry
spirally coiled heating unit means 23 that has the ter
minal ends 24 thereof associated with a terminal block
25, there being a heat reflecting and spillage collecting
pan 26 supported in the mounting ring 21 in a position
attached to the frame or spider in a manner providing 65 beneath the spider 22 and the heating means 23.
The mounting ring 21 has a generally horizontal an
relative movement of the coils on the frame or spider to ‘
nular ?ange 27 that is adapted to rest upon the cooking
permit such expansion and contraction thereon without
top (not shown), and at the inner edge of the horizontal
affecting the certainty and permanence of the attach
?ange 27 a downwardly extending substantially vertical
ment of the winding to the spider and in accordance with
the present invention this is accomplished by employing 70 annular wall 28 is formed, the lower end of which has
a narrow inwardly extended horizontal support ?ange
fasteners at appropriate places which are positively and
29. The lower supporting ?ange 29 serves to support
3,024,345
the pan 26, which has an annular ?ange or rim 30 that
rests upon the horizontal ?ange 29 of the mounting ring.
The pan 25 is relatively deep, and has a sloping or coni
cal surrounding wall, for reasons explained hereinafter,
and at its rear side the pan 26 has a clearance opening
31 formed therein, this clearance opening being in the
nature of a wide notch that extends to the upper edge of
the pan, and provides clearance through which the ter
minal ends 24 of the heating means 23 may extend, and
4
employed having short upper arms 42 substantially
paralleling the coils and welded to the underside thereof
and having the legs 43 thereof welded near their lower
ends to embossments 44 pressed from the spider arms 34,
all as shown particularly in FIGS. 2 and 3.
The coil of the heating unit is fastened to the spider
arm in a position in which it rests on the upper edge of
the spider arm, and the spider arms 34 are of such ?exi
bility that, although the heating elements 23A and 23B
are securely attached to the spider 22, such increase and
within which such terminal ends may move when the 10
decrease in length of the coil between the two places
heating element is pivoted to its elevated position as de
scribed hereinafter.
The spider 22 is formed from a pair of sheet metal
perature changes, is readily accommodated by the ?exi<
strips that have corresponding portions 32 between their
coil portion is accommodated by permissible twist or
ends fastened together by rivets 33 or in any other con
venient manner, and at one end of the portions 32 the
sheet metal members are bent to a diverging relation
ship to provide forward arms 34, while at the other or
rear end of the portions 32 the sheet metal members are
of fastening thereof which occurs on account of tem
bility of the arms 34, and any change in arcuity of the
bending of the wire of the inverted L-shaped wire
fasteners 41.
As will be evident in FlG. 1, the heating elements 23A
and 23B are wound in a double spiral and at the outer
ends of the spirals are bent downwardly as at 45 and are
bent in a diverging relationship to provide diverging rear 20 then bent outwardly at 46 to provide the relatively short
arms 35. The arms 34 and 35 are of such a length that
terminal portions 24, and at the inner ends of the spirals
the ends thereof may be located over the ?ange 29 so
the heating elements 23A and 23B are likewise bent down
as to be supported thereon, it being noted however, that
wardly as at 47 and then outwardly as at 48 to provide the
such support is in most instances obtained by resting on
relating long terminal portions 24 as shown in FIG. 1
the ?ange 30 of the pan 26 as will be evident in FIG. 1
The downwardly extending portions 45 and 47 are so
of the drawings. At their outermost ends, the rear arms
related that the several terminal portions 24 may extend
35 of the spider have integral extensions providing con
parallel to each other beneath the hinge 39 and toward
nector arms 36 that are bentso as to extend generally
the terminal block 25.
toward each other as shown in FIG. 1. At the inner
The heating elements 23A and 23B are of conventional
30
ends of the connector arms 36 the sheet metal strips are
bent into a spaced parallel relationship so as to extend
rearwardly and provide hinge arms 37. The hinge arms
37 provide a portion of the hinge means whereby the
spider 22 is pivotally hinged to the mounting ring 21,
and in providing this hinged relationship the hinged arms
37 extend through spaced vertical slots 38 that are formed
in the vertical ?ange 28 of the mounting ring. These
form, each comprising a tubular metal sheath 49 con
taining a central helical resistance 50 which is embedded
in heat conductive electrical insulating material 51, such
as magnesium oxide powder, compacted to a hard dense
mass which electrically insulates the resistance from the
sheath.
The ?at winding composed of the spiral portions of the
heating elements 23A and 23B constitutes the active por
slots have their opposite edges offset in opposite direc
tion of the heating unit and accordingly the resistances 50
tions as shown more particularly in my aforesaid applica
40 of the heating elements 23A and 2313, in accordance with
tion Serial No. 662,041, to provide opposed arcuate bear
conventional practice, extend to or into the downturned
ing seats to receive and support the ends of a hinge pin
portions 45 and 47 where they are electrically connected
39. The hinge pin 39 extends at its opposite ends through
to low resistance terminal conductors which extend there
pivot openings in the hinge arms 37 and the hinge
from out through the bends 46 and 48 and through the
pin is supported therebeyond in the bearing seats at the
terminal portions and project from the sheath ends, as
slots 33 and thus the spider 22 may be swung from its
indicated at 52 for attachment of current supply con
normal horizontal position to an upraised position.
ductors thereto.
The heating means 23, as illustrated herein, is made
The terminal portions 24 extend an equal distance out
up of two elongated sheath type electrical heating ele
wardly under the range top (not shown) so as to ter
ments 23A and 238 that are wound in a double ?at spiral
minate at a place where they are safely protected against
as will be evident in FIG. 1 with the coils of the ele
spillage from cooking operations on the heating unit,
ments 23A and 23B intercalated, and in the relatively
and their outer ends are arranged to extend into pockets
large central space within the spirals an escutcheon plate
53 of the terminal block 25 in which provision is made
4i) is mounted on the spider 22. It is to be noted that
for connection of current supply wires to the exposed pro
the heating element 23A is formed with three coils and
jecting ends 52 of the terminal conductors.
provides the inner and outer coils of the winding, where
This terminal block 25 is of ceramic material and is
as the heating element 2313 has two coils, both of which
formed with a bottom wall, from which side walls 54
are intercalated between coils of the element 23A.
and intermediate walls 55 extend upwardly from the bot
The heating elements expand and contract in the heat
tom wall and all said walls 54 and 55 extend forwardly
ing and cooling thereof, and because of the spiral form
from a relatively thick rear or outer end wall 56 having
a slight radial expansion and contraction of the coils 60 openings 57 therethrough to accommodate current supply
occurs, and it is important that the spiral elements be
conductors.
suitably mounted so that they are free to expand and
Between the two intermediate walls 55 and between one
of these walls 55 and one of the side walls 54, two small
contract in accordance with temperature changes.
To this end only the outer coil of each element 23A
pockets 53 are formed to accommodate respectively there
and 23B is attached to the spider 22 and only at places 65 in terminal clips 59 and 6t}, and between one of said walls
55 and the other side wall 54 a large pocket 53 is formed
remote from the hinge 39 and the terminal ends 24. Thus
the outer coil of each element 23A and 23B is secured to
to accommodate a large common terminal clip 61 therein,
the forward arms 34 only of the spider as shown in
and each of said pockets has one of the openings 57
leading therefrom through the rear or outer end wall 56.
FIG. 1.
For this purpose of securing these outer coils to the 70 The terminal clips 59 and 653 are associated respectively
spider arms 34, wire fasteners are employed which are
with the corresponding long ends 24 of the two heating
welded to the coils and to the spider arms at spaced
elements 23A and 2313 which have the projecting ter
apart places providing an intermediate portion of a resili
minal wires 52 thereof welded to the respective clips 59
ency to permit relative movement of the coils on the
spider. Wire fasteners 41 of inverted L-shape may be 75 and 60.
3,024,345
The other terminal clip 61 constitutes the common ter
minal for the two heating elements 23A and 23B as will
be evident in FIG. 1 of the drawings, and the clip 61 is
therefore connected to both of the terminal wires 52 of
the other short ends 24 of the heating elements 23A and
23B. Three line wires 62 are shown and each extends
through a respective one of the openings 57 through the
rear wall 56 and said wires are secured to the respective
terminal clips by screws 64.
For holding the terminal block 25 on the outer ends’
of the terminal portions 24 and protecting the terminal
block and terminal connections against grease and spill
age, two inner end cover plates 63 of sheet metal are pro
vided at the inner end of the terminal block and which
conjointly extend substantially entirely across the inner
end of the terminal block.
These plates 63 are alike, except that one has a ground
screw 64 thereon, and one thereof is secured to the outer
ends of the short terminal portions 24 which lead from the
5
stems of the heating unit winding are connected to the
terminal block and provided with terminal wires and
clips contained in pockets of the terminal block as in
FIG. 1.
The spider, which is indicated as a whole at 69, is
composed of a center strip 70, which extends diametrical—
1y from front to rear of the opening in the ring 66, and
has a pair of opposite side strips 71 secured centrally
thereto, and the forward end of the center strip 70 and
outer ends of the side strips 71 are supported on the
o-utturned margin of the pan 67 which in turn rests on
the inturned bottom ledge of the upright annular wall 72
of the ring 66 to support the spider in the same manner
as the spider is supported in FIG. 1.
At its rear end, the center strip is pivoted to a bracket
73 which is attached to the upright annular wall 72 of
the ring 66 so that the spider 69 and heating unit wind
ing thereon swing to an upraised position at the rear of
the ring, and at its forward end the strip 70 may have
outer coils respectively of the spiral windings of the two
heating elements 23A and 23B and the other is secured
to the outer ends of the long terminal portions 24 which
lead from the inner coils respectively of the spiral wind
ings of the two heating elements 23A and 23B.
In the expansion and contraction of the heating ele
ments under the changes of temperature to which they
into an opening 76 in the upright annular wall 72.
The heating means 77 of FIG. 4, like that of FIG. 1,
is composed of two elongated tubular sheathed elements
77A and 77B wound in a double ?at spiral with their
24 which are connected to the one plate 63 tend to move
to a separate one of the strips or arms 71, each by a
a nose portion 74, such as shown in FIG. 12, which snaps
under a latch 75, or as shown in FIG. 12, it may snap
coils intercalated, each however having two coils instead
are subjected, the coils thereof tend to expand and con
of two and three coils respectively as in FIG. 1, and
tract and by reason thereof the terminal portions 24 at
these coils of the elements 77A and 77B are attached to
the opposite ends of each element tend to move toward
and away from one another and as the corresponding ends 30 the arms of the spider 69 by wire fasteners 78 and 79
which are illustrated in detail in FIGS. 5, 6 and 7, the
of each heating element 23A and 23B tend to move
inner coil of each element 77A and 7713 being connected
similarly in this manner the two short terminal portions
fastener 78, and the outer coils of both elements 77A
and 77B being conjointly connected to the forward end
portion of the center strip 70 by a fastener 79, all as
thus by employing separate plates 63, expansion and con
shown in FIG. 4.
traction of the coils is accommodated and each element
Each fastener 78, as shown more particularly in FIGS.
23A and 23B is free to expand and contract.
5 and 6, is composed of a length of wire which is bent
Moreover the pockets 53 in which the terminal clips
59, 60 and 61 are located are of su?iciently greater width 40 approximately at its midlength to provide two legs 80
and 81 disposed substantially at right angles to one an
than the clips located therein so that these clips are free
other, and each leg 80 and 81 has an end portion of the
to move sidewise in their pockets to permit freedom of
wire bent laterally therefrom, both preferably in the same
expansion and contraction of the coils of the elements
direction, to provide arms 82 and 83 extending substan
23A and 23B.
tially at right angles from the outer ends respectively of
The plates 63 are located quite close to one another,
the legs 80 and 81.
substantially as shown in FIG. 1, when the heating ele 45
FIGS. 5 and 6 show the fastening of the inner coil of
ments 23A and 23B are at normal room temperature and
the element 77B to its supporting spider arm 71, and as
separate to some extent when the heating elements 23A
shown therein, one of the fastener arms, for example, the
and 23B are energized, and the terminal block 25 is at
similarly toward and away from the long terminal por
tions 24 which are connected to the other plate 63 and
arm 83, is welded as at 84 to the side of the spider arm
tached to the ends of the terminal portions 24 and to
the plates 63 in a manner to permit such relative move 50 71 so that it extends substantially horizontally therealong
with its leg 81 extending upwardly along the side of the
ment of the plates 63 with respect to one another and
spider arm 71 and positioned so that the top leg 80 and
corresponding movement of the ends of the terminal por
arm 82 are at the proper level for fastening the inner
tions 24 which are attached to the plates.
77B coil to the spider arm 71, and with the legs 80 and
The plates 63 are permanently secured to the respec
tive pairs of terminal portions 24 in a manner to provide 55 81 offset laterally from the 77B coil with the bottom
apex portion of the coil sheath extending crosswise over
a sealed connection which will preclude passage of grease
the arm 82 distantly from its leg 80 and at that place
or spillage therethrough, and for this purpose the ter
of crossing, the arm 82 is Welded as at 85 to the bottom
minal portions 24 pass through plate openings which have
of the inner coil of element 778.
annular ?anges 65 projecting therefrom which are staked
The inner coil of the element 77A is in like manner
onto the sheaths of the terminal portions 24 or welded 60
fastened to the other arm 71' of the spider, and it is to be
thereto to ?xedly secure the plates 63 to the terminal
noted that each fastener 78, while providing a perma—
portions 24 and provide a leak-proof connection.
nent attachment of the heating element coil to the spider
Greater ?exibility of the coil fasteners to accommodate
arm, is formed with three approximately right angled
twisting strains and to permit sliding movement of the
coils lengthwise and transversely of the spider arms at 65 bends and four angularly disposed leg and arm portions
between the places of welding to the spider arm 71 and
the places of fastening may be provided by employing
to the coil of the respective element 77A and 7 7B, thereby
fastener wires of additional length with added bends be- '
providing substantial length of wire and bendable dis
tween the places of welding thereof to the spider arm
position thereof for yieldability to permit any movement
and the heating unit coil, examples of which are shown
70 of the coil which may be caused by expansion and con
in FIGS. 4 to 13 inclusive.
traction of the coils of the heating element.
Referring ?rst to FIG. 4, which shows a heating unit
The fastener 79, which is shown in FIGS. 7 and 8,
and mounting assembly, the mounting ring 66 and pan
is in effect a double form of the fastener 78 having right
67 and terminal block 68 thereof are of substantially
the same construction as in FIG. 1 and the terminal 75 and left hand fasteners 78 joined by a common wire con
nector portion 86 which is welded centrally as at 87 to the
3,024,345
7
side of the center strip 70 of the spider with the opposite
end portions thereof serving as the bottom arms 83 of
the two thus connected fasteners 78, each of which has
legs 80 and 81 and a top arm 82, which are inturned
toward one another and properly spaced by the common
connector 86 so that they extend respectively underneath
the adjoining outer coils of the two elements 77A and
778 to which they are respectively welded at 85.
Thus each outer coil of the elements 77A and 77B is
permanently attached to the center strip 70 of the spider
with the same yield'ability to permit movement of the
respective coil, as in the case of the fastening of the inner
coils by the fasteners 78.
8
the skeleton frame and to the bottom of a coil which
rests on and extends transversely across the upwardly
presented edge of that arm, the said wire having the
length thereof between said spaced apart places in excess
of the distance therebetween and bendably and twistably
responsive to the expansion and contraction of the coil
to which it is attached to permit sliding movement of said
coil on the upwardly presented edge of the arm to which
it is attached.
2. A tubular sheathed embedded resistor heater as de
?ned in claim 1 in which the said length of wire is formed
with a bend with legs extending therefrom at an angle to
one another and leading respectively to the spaced apart
places at which the wire is ?xedly secured permanently
Another form of coil fastener is shown in FIGS. 9
to the side of the arm and to the bottom of the coil.
15
and 10 and comprises a length of wire bent in S-shape
3. A tubular sheathed embedded resistor heater as de
with top and bottom arms 88 and 89 respectively disposed
?ned in claim 1 in which said length of wire is formed
in generally parallel relation to one another and each
with a plurality of bends at spaced apart intervals between
having a return bend 90 at one end with intermediate
the spaced apart places at which the wire is ?xedly se
portion 91 of the Wire connecting the return bends to one
cured permanently to the side of the arm and to the
another.
bottom
of the coil.
The bottom arm 88 of this fastener is welded as at 92
4. A tubular sheathed embedded resistor heater as de
to a spider arm 93 so that the fastener leans outwardly
fined in claim 1 in which said length of wire is formed
and upwardly at a slope, as indicated in FIG. 10, and
with a bend from which two leg portions extend, one of
has the upper arm 80 thereof extending crosswise under
which said leg portions extends downwardly along said
the heating element coil 94 and welded thereto at 95.
one side of the arm of the skeleton frame and the other
A double form of the fastener of FIGS. 9 and 10 is
of which said leg portions extends laterally from said
shown in FIG. 13 in which two fasteners of the FIGS. 9
arm at the top thereof.
'
and 10 form have a common connecting wire portion 96
5. A tubular sheathed embedded resistor heater as de
providing conjointly the bottom legs 89 of the two fas
?ned in claim 1 in which said length of wire is formed
teners and centrally welded at 97 to a spider arm 98, with 3O with a bend from which two leg portions extend, one of
the top legs 38 of the two fastener par-ts welded at 99
which said leg portions extends downwardly along said
to adjoining heating element coils 100 and 101 in the
one side of the arm of the skeleton frame and the other
same manner as in FIGS. 9 and 10.
of which said leg portions extends laterally from said arm
Another form of coil fastener is shown in FIGS, 12
at the top thereof, and each leg portion has a portion of
and 13, which, like the fastener of FIGS. 5 and 6, is a
said length of wire at the outer end thereof extending
length of wire bent to provide legs 102 and 103 disposed
laterally therefrom to one of the spaced apart places
substantially at right angles to one another, the upper
where the length of wire is ?xedly secured permanently
one 102 of which has an arm 104 bent laterally there
to one side of an arm of the skeleton frame and to the
from at its outer end and extending transversely under 40
bottom of a coil.
and is welded as at 105 to a heating element coil 106 in
6. A tubular sheathed embedded resistor heater as de
the same manner as the arm 82 of the fastener of FIGS.
?ned in claim 1 in which said length of wire has lateral
5 and 6 is welded to the heating element coil.
ly spaced generally parallel portions disposed respective
The other leg 103, however, which extends downwardly
ly at said spaced apart places and said portions extend
along the side of the spider arm 107 is looped at its lower
angularly from the respective outer ends of two leg por
tions of said length of wire which are disposed at an angle
end to form a U-shaped return bend 108 with an up
wardly extending leg 109 which is welded approximately
to one another.
at its midlength to the side of the spider arm 107.
7. A tubular sheathed embedded resistor heater as de
?ned in claim 1 in which said length of wire is formed
lower portion thereof with an embossment providing a
with a bend from which two leg portions extend, one
rib 110 at one side to which the upwardly extending leg 50 of which said leg portions extends downwardly along
109 is welded, as indicated at 111 in FIG. 13, and the
vsaid one side of the arm of the skeleton frame and the
leg 103 extends divergently away from the side of the
other of which said leg portions extends laterally from
spider arm as shown in FIG. 13.
said arm at the top thereof, and the leg portion which
Preferably the spider arm 107 is provided along the
While I have shown and described my invention in a
preferred form, I am aware that various changes may
extends downwardly along said one side of the arm of
the skeleton frame terminates in a return bend having an
be made therein without departing from the principle of
the invention, the scope of which is to be determined by
upturned portion which is ?xedly secured permanently to
said arm and the leg portion which extends laterally from
the appended claims.
said arm at the top thereof has a laterally bent portion at
What I claim is:
the outer end ?xedly secured permanently to the bottom
l. A tubular sheathed embedded resistor heater having 60 of the coil.
coils thereof distributively arranged in the form of a flat
8. A tubular sheathed embedded resistor heater as de
winding, the coils of which expand and contract in the
?ned in claim 1 in which said length of wire is formed
plane of the winding according to changes of tempera
in a general S-shape and extends divergently outward
ture thereof, a skeleton type frame underneath and sup
porting the winding and having arms with upwardly pre
sented edges across which the coils extend transversely
65 from an arm of the skeleton frame and at the top and
and upon which the coils rest slidably for movement
thereon in the expansion and contraction thereof by said
temperature changes, and fastening means by which the 70
winding is attached to the frame with permissible freedom
of slidability of the coils on the arms for expansion and
contraction thereof, the fastening means comprising a
wire which is ?xedly secured permanently at spaced apart
places therealong respectively to one side of an arm of 75
bottom of the S-shape is ?xedly secured permanently re
spectively to the bottom of the coil and to the side of
said arm.
References Cited in the ?le of this patent
UNITED STATES PATENTS
2,725,456
2,881,302
2,943,178
Weyrick ____________ __ Nov. 29, 1955
Ammerman __________ __ Apr. 7, 1959
Aldous ______________ __ June 28, 1960
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