U.S. patent number RE34,018 [Application Number 07/581,420] was granted by the patent office on 1992-08-04 for heating coil assembly.
This patent grant is currently assigned to Wagner Spray Tech Corporation. Invention is credited to Walter J. Petersen, John M. Svendsen.
United States Patent |
RE34,018 |
Petersen , et al. |
August 4, 1992 |
Heating coil assembly
Abstract
A heating coil assembly for use in an air blower device has an
annular support element, a first end cap, a core having a heating
coil spirally wound thereon, a sleeve surrounding the coil and
core, and a second end cap. All components have a centrally
disposed non-circular bore therein for receiving a heavy gauge
non-circular wire retainer, swaged at one end, which extends
through the entire assembly and is retained by a press washer at an
opposite end. The interior of the sleeve is spaced from the coil
forming an axial channel for air flow over the coil. Axial openings
in the end caps form air inlets and outlets for the channel. The
coil has several leads, at least one of which extends through an
axial opening in one of the end caps. The heating coil assembly has
a small number of components, which are easily assembled and
simultaneously axially and radially positioned and retained
relative to each other by the wire retainer.
Inventors: |
Petersen; Walter J. (Eden
Prairie, MN), Svendsen; John M. (New Hope, MN) |
Assignee: |
Wagner Spray Tech Corporation
(Minneapolis, MN)
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Family
ID: |
27401697 |
Appl.
No.: |
07/581,420 |
Filed: |
September 12, 1990 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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264382 |
Oct 31, 1988 |
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Reissue of: |
639371 |
Aug 8, 1984 |
04636617 |
Jan 13, 1987 |
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Current U.S.
Class: |
338/303;
174/138J; 219/546; 219/550; 338/268; 338/270; 338/321; 34/667;
34/97; 392/379; 392/383; 392/485 |
Current CPC
Class: |
H05B
3/46 (20130101) |
Current International
Class: |
H05B
3/42 (20060101); H05B 3/46 (20060101); H05B
003/00 (); F24H 003/04 (); H01C 003/20 () |
Field of
Search: |
;219/534,546,550
;392/379-385,485-495,360-369,370-376,480-484
;338/296,302,303,298,321 ;34/96-101,243R |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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205446 |
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Jun 1972 |
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DE |
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124963 |
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Mar 1928 |
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CH |
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250103 |
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May 1948 |
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CH |
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591966 |
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Sep 1947 |
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GB |
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993320 |
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May 1965 |
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GB |
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Primary Examiner: Bartis; Anthony
Attorney, Agent or Firm: Hill, Van Santen, Steadman &
Simpson
Parent Case Text
.Iadd.This is a continuation of application Ser. No. 264,382 filed
Oct. 31, 1988, now abandoned. .Iaddend.
Claims
We claim as our invention:
1. A heating coil assembly for use in a heavy duty hot air blower
comprising:
an axially elongated ceramic core;
a heating coil .[.helically.]. wound on said core and having a
plurality of electrical leads;
an axially elongated hollow ceramic sleeve surrounding and spaced
from said core and coil and defining an axial air flow passage
between said sleeve and said core about said coil;
a pair of ceramic end caps having a plurality of radial vanes
defining axial apertures aligned with said air flow passage
disposed at opposite ends of said core and coil and forming in
combination with said sleeve a ceramic insulating shell completely
surrounding said core and coil, at least one of said leads
extending through said apertures in one of said end caps;
an annular support element disposed adjacent said one of said end
caps and receiving said leads;
each of said core, said end caps and said annular support element
having a centrally disposed .[.non-circular.].bore therein; and
a retainer .Iadd.means .Iaddend.having a non-circular
crossection.]. .Iadd.cross-section .Iaddend. corresponding to the
cross-section of said bore extending through said core, said end
caps and said annular support element for .[.simultaneously.].
axially .[.and radially fixing and.]. restraining said core, said
end caps and said annular support element.
2. A heating coil assembly as claimed in claim 1 wherein each of
said end caps comprises:
an outer rim;
a centrally disposed hub through which said .[.polygonal.]. bore
extends; and
said radially extending vanes connecting said rim and said hub.
3. A heating coil assembly as claimed in claim 2 wherein said vanes
and said hub have a larger axial dimension than said rim so as to
extend into said hollow ceramic sleeve.
4. A heating coil as claimed in claim 1, wherein said plurality of
electrical leads is three, and wherein said ceramic core has a
first slot therein for receiving a first and said leads, an axial
channel extending along the entire length of said core for
receiving a second of said leads therein along the length of said
core, and a pair of spaced radially extending posts disposed on an
exterior of said core at an end thereof adjacent said one of said
end caps for receiving a third of said leads.
5. A heating coil assembly as claimed in claim 4 wherein said
ceramic core further includes a second slot disposed at an opposite
end of said core from said first slot, said channel for said second
lead communicating with said second slot for bringing said second
lead to said exterior of said core.
6. A heating coil assembly as claimed in claim 1 wherein said
annular support element has a means for connecting said support
element to a hot air blower.
7. A heating coil assembly as claimed in claim 1 wherein said
annular support element comprises:
an exterior rim;
a centrally disposed boss through which said retainer .Iadd.means
.Iaddend.extends; and
a plurality of radially extending struts connecting said rim and
said boss.
8. A heating coil assembly as claimed in claim 7 further comprising
a spacer disposed in said annular support element between said boss
and said one of said end caps, said spacer having a centrally
disposed bore through which said retainer .Iadd.means
.Iaddend.extends.
9. A heating coil assembly as claimed in claim 8 wherein said
spacer is comprised of ceramic material.
10. A heating coil assembly as claimed in claim 1 further
comprising means disposed at opposite ends of said retainer
.Iadd.means .Iaddend.for restraining axial movement of said
retainer .Iadd.means .Iaddend.relative to said core, support
element, end caps and sleeve.
11. A heating coil assembly as claimed in claim 10 .Iadd.wherein
said retainer means is a shaft extending through said bores in said
core, said end caps and said annular support element, and
.Iaddend.wherein said means for restraining axial movement of said
retainer .[.include.]. .Iadd.means is .Iaddend.a swaged end of said
.[.retainer.]. .Iadd.shaft.Iaddend..
12. A heating coil assembly as claimed in claim 10 .Iadd.wherein
said retainer means is a shaft extending through said bore in said
core, said end caps and said annular support element, and
.Iaddend.wherein said means for restraining axial movement of said
retainer .[.includes.]. .Iadd.means is .Iaddend.a press fit
retaining washer disposed at one end of said .[.retainer.].
.Iadd.shaft .Iaddend.adjacent said annular support element.
13. A heating coil assembly for use in a heavy-duty hot air blower
comprising:
an elongated ceramic core having an outer circumferential surface
having a .[.helical.]. groove therein extending from one axial end
of said core to an opposite axial end of said core;
a heating element .[.helically.]. wound about said core in said
groove, .[.said groove having a depth less than a radial height of
said heating element such that said heating element projects above
said outer circumferential surface of said core,.]. said heating
element having a plurality of leads;
an elongated sleeve surrounding said core and having an inner
surface spaced from said outer circumferential surface defining an
annular axial air flow space between the core and the sleeve,
two ends caps respectively disposed at said axial ends of said
core, said end caps having means for maintaining the spacing of
said inner surface from said outer circumferential surface, each
end cap having a plurality of radial vanes defining axial apertures
in said end caps in axial registry with said air flow space, and at
least one end cap further having means for providing access for at
least one of said heating element leads to an exterior of said
assembly; and
means for axially retaining said end caps in assembled relation
with said core and said sleeve .[.and having means cooperating with
means on said core and said end caps for preventing relative
rotational movement thereof.]..
14. A heating coil assembly as claimed in claim 13, wherein each
end cap consists of ceramic material.
15. A heating coil assembly as claimed in claim 13, wherein said
sleeve consists of a ceramic material.
16. A heating coil assembly as claimed in claim 13, wherein the
plurality of leads for said heating element is three, two of said
leads being electrically connected to opposite ends of said coil at
opposite ends of said core, and one of said leads being
electrically connected to said coil at an intermediate position
along the axial length of said core.
17. A heating coil assembly as claimed in claim 13, wherein said
means in at least one end cap for providing access for at least one
of said heating element leads to an exterior of said assembly is an
axial opening in said one of said end caps.
18. A heating coil assembly as claimed in claim 17, wherein one of
said leads for said heating element extends through said axial
opening and wherein another of said heating element leads extends
through one of said axial apertures defined by said radial
vanes.
19. A heating coil assembly as claimed in claim 13, wherein said
means for .[.axial.]. .Iadd.axially .Iaddend.retaining said end
caps in assembled relation is a shaft extending axially through
respective centrally disposed bores in said end caps and said core
with opposite ends of said shaft projecting beyond said end caps,
and a pair of axially stationary washers disposed at said
projecting ends of said shaft.
20. A heating coil assembly as claimed in claim .[.19.]. .Iadd.29,
wherein said means for axially retaining is a shaft extending
axially through respective centrally disposed bores in said end
caps and said core, and wherein said shaft and said bores have
corresponding non-circular cross-sections serving as said means
cooperating with means on said core and said end caps for
preventing relative rotational movement thereof.
21. A heating coil assembly as claimed in claim 13, wherein each of
said end caps has a circular projection received at opposite ends
of said sleeve for radially fixing the position of said end caps
relative to said sleeve.
22. A heating coil assembly as claimed in claim 13, further
comprising a support element disposed adjacent said one of said end
caps, and wherein said means for axially retaining said end caps in
assembled relation with said core and said sleeve additionally
retains said support element in assembled relation therewith.
23. A heating coil assembly as claimed in claim 22, wherein said
support element has .Iadd.an aperture therein and has .Iaddend.a
centrally disposed boss within .Iadd.said .Iaddend.aperture
.[.therein.]., and wherein said means for axially retaining said
end caps, said sleeve and said support element in assembled
relation is a shaft extending axially through said boss, said end
caps and said core, and further comprising a spacer surrounding
said shaft disposed in the interior of said support element between
.Iadd.said .Iaddend.one of said end caps and said boss.
24. A heating coil assembly as claimed in claim 23, wherein said
spacer consists of a ceramic material.
25. A heating coil assembly for use in a heavy-duty hot air blower
comprising:
an elongated ceramic core having an outer circumferential surface
having a .[.helical.]. groove therein extending from one axial end
of said core to an opposite axial end of said core;
a heating element .[.helically.]. wound about said core in said
groove, .[.said groove having a depth less than a radial height of
said heating element such that said heating element projects above
said outer circumferential surface of said core,.]. said heating
element having a plurality of leads;
an elongated sleeve surrounding said core and having an inner
surface spaced from said outer circumferential surface defining an
annular axial air flow space between the core and the sleeve,
two ends caps respectively disposed at said axial ends of said
core, said end caps having means for maintaining the spacing of
said inner surface from said outer circumferential surface, each
end cap having a plurality of radial vanes defining axial apertures
in said end caps in axial registry with said air flow space;
means for providing access for at least one of said heating element
leads to an exterior of said assembly; and
means for axially retaining said end caps in assembled relation
with said core and said sleeve .[.and having means cooperating with
means on said core and said end caps for preventing relative
rotational movement thereof.].. .Iadd.
26. A heating coil assembly as claimed in claim 1 further
comprising:
means for preventing relative rotation of said core and said end
caps. .Iaddend. .Iadd.27. A heating coil assembly as claimed in
claim 26 wherein said retainer means is a shaft extending through
said bore in said core, said end caps and said annular support
element, and wherein said shaft and said bores have corresponding
non-circular cross-sections serving as said means for preventing
relative rotation. .Iaddend. .Iadd.28. A heating coil assembly as
claimed in claim 1 wherein said coil is helically wound on said
core. .Iaddend. .Iadd.29. A heating coil assembly as claimed in
claim 13 further comprising:
means on said means for axially retaining cooperating with means on
said core and said end caps for preventing relative rotational
movement thereof. .Iaddend. .Iadd.30. A heating coil assembly as
claimed in claim 13 wherein said groove is a helical groove.
.Iaddend. .Iadd.31. A heating coil assembly as claimed in claim 13
wherein said groove has a depth less than a radial height of said
heating element such that said heating element projects above said
outer circumferential surface of said core. .Iaddend. .Iadd.32. A
heating coil assembly as claimed in claim 25 further
comprising:
means on said means for axially retaining cooperating with means on
said core and said end caps for preventing relative rotational
movement thereof. .Iaddend. .Iadd.33. A heating coil assembly as
claimed in claim 32 wherein said means for axially retaining is a
shaft extending axially through respective centrally disposed bores
in said end caps and said core, and wherein said shaft and said
bores have corresponding non-circular cross-sections serving as
said means cooperating with means on said core and said end caps
for preventing relative rotational movement
thereof. .Iaddend. .Iadd.34. A heating coil assembly as claimed in
claim 25 wherein said groove is helical. .Iaddend. .Iadd.35. A
heating coil assembly as claimed in claim 25 wherein said groove
has a depth less than a radial height of said heating element such
that said heating element projects above said outer circumferential
surface of said core. .Iaddend.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to heating coil assemblies, and in
particular to a heating coil assembly suitable for use in a heavy
duty hot air blower.
2 Description of the Prior Art
Heating coil assemblies are known in the art for use in various
types of hot air blowing devices, such as paint-removing blowers,
hair dryers and the like. Conventional heating coil assemblies are
generally positioned adjacent to a blower fan and have a resistance
heating element, generally in the form of a coil wire, disposed
such that the blower moves air to be heated axially over the coil,
such that when the air exits the assembly it has been elevated in
temperature by the coil.
Many conventional units simply have the coil, and supporting means
therefor, disposed openly within the housing of the blower device,
such that the air passage surrounding the coil is a relatively
large volume defined by the coil itself and the interior wall of
the housing. Examples of such conventional devices are described in
U.S. Pat. Nos. 3,943,329; 3,947,659; 3,109,083; 2,778,919;
2,730,609; 2,041,687; 1,955,240; 1,821,525 and 1,777,744.
Other known heating coil assemblies have a sleeve or other interior
means surrounding the coil in the inside of the device housing, so
as to define a smaller volume for passage of air over the coils.
Examples of devices of this type are described in U.S. Pat. Nos.
4,198,556; 3,857,016; 3,668,370; 3,612,824 and 3,094,606.
A problem existing in the field of heating coil assembly
manufacture is that of providing a reliable heating means which can
be utilized for purposes requiring a sufficient volume of extremely
hot air, such as for removing paint from a surface by causing the
paint to blister by the application of intense heat thereto, is
that of providing a heating element which meets these demands which
is inexpensive, easy to assembly, and has relatively few elements.
A further problem in the design and manufacture of such heavy duty
heating elements is to provide such an element which generates
sufficient heat for elevating the temperature of a large volume of
air but which is sufficiently insulated from the remainder of the
device so as to not cause a danger to the user.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a heating coil
assembly for use in a heavy duty hot air blowing device which
consists of a small number of elements which are easily assembled
and retained.
It is a further object of the present invention to provide a means
for assemblying the heating coil assembly which simultaneously
axially and radially positions and retains the elements
thereof.
It is a further object of the present invention to provide such a
heating coil assembly which rapidly and effectively elevates the
temperature of a high volume of moving air yet provides sufficient
insulation from surrounding components so as to minimize heat
transfer thereto, thereby contributing to safer operation of the
device containing the assembly.
The above objects are inventively achieved in a heating coil
assembly having an annular mounting element, which may be comprised
of plastic, and two ceramic end faces with a ceramic core about
which a resistance heating element is spirally wound and a ceramic
sleeve disposed therebetween. Each element has a polygonal
centrally disposed bore therein for receiving a heavy gauge
polygonal wire retainer therethrough. The retainer is swaged at one
end and is fitted with a press fit washer at its opposite end for
simultaneously axially and radially positioning and retaining all
of the elements, and further facilitating ease of assembly of the
elements.
Each of the end faces which are disposed adjacent the insulating
sleeve surrounding the heating element have vanes extending toward
the interior of the sleeve which are received in the sleeve so as
to form in combination a cylindrical insulating shell for the
heating element.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a sectional view of a heating coil assembly constructed
in accordance with the principles of the present invention.
FIG. 2 is an end view of the heating coil assembly shown in FIG.
1.
FIG. 3 is an exploded perspective view of the heating coil assembly
shown in FIG. 1.
FIG. 4 is a circuit diagram for the heating coil in the assembly
shown in FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
A heating coil assembly constructed in accordance with the
principles of the present invention is generally referenced at 1 in
FIG. 1. The assembly 1 has an annular support element 2, which may
be comprised of plastic, and a hollow cylindrical ceramic sleeve 3
closed at each end by respective ceramic end caps 4 and 5. Each end
cap 4 and 5 has an outer rim and a central hub 9 from which a
plurality of struts or vanes, such as 6a and 6b that radially
extend so as to define a plurality of annularly disposed openings
vents or radial apertures 6 in the end cap 4, and the like
plurality of vanes such as 8a and 8b define openings or vents
radial apertures 8 in the end cap 5. The hubs 9 for each of the end
caps 4 and 5, and the vanes radially extending therefrom, extend
slightly into the interior of the ceramic sleeve 3 so as to form a
shoulder in combination with the outer rim of the caps 4 and 5 so
as to provide a ceramic insulating shell or housing in combination
with the sleeve 3. A ceramic core 10 is centrally disposed within
the interior of the housing formed by the sleeve 3 and the end caps
4 and 5. The core 10 has a helical groove 11 formed thereon which
receives a helical spiral heating coil 12. The heating coil 12 is
of the type well known to those skilled in the art and may consist,
for example, of heavy gauge resistance wire. The flights of the
coil 12 may be further separated and insulated by small projections
13 on the core 10.
As shown in the circuit diagram in FIG. 4, the coil 12 has a center
tap 18 and two end terminals 15 and 39. The center tap 18 is guided
within a radial slot 35 in the core 10 to the end of the core 10,
at which point the wire 18 enters an aperture 7 in the end cap 4
and is connected to an exterior wire 17 by a connector 19. One end
terminal 15 of the coil 12 is received and retained between two
spaced posts 42 formed on the core 10 and is conducted through one
of the apertures 6 in the end cap 4, wherein it is connected to
another exterior wire 14 by another connector 16. The other end
terminal 39 of the coil 12 extends through an axial channel 36
within the core 10, the channel 36 terminating in a radial slot 37
adjacent the end cap 5. The wire 39 is conducted through the
channel 36 and the slot 37 for connection to the coil 12. The
opposite end of the terminal 39 is conducted through another
opening 41 in the end cap 4 wherein it is connected to another
exterior wire 20 by means of another connector 38.
The annular support element 2 has a plurality of exterior vanes 22
radially disposed around the periphery thereof for positioning and
retaining the support element 2, and the remainder of the assembly
connected thereto, in a housing (not shown) of the blower device in
which the heating coil assembly 1 is to be employed. The annular
support element 2 further has a centrally disposed boss 25 from
which a plurality of ribs or struts 21 radially extend toward the
outer rim thereof. The outer rim has a passage 23 for permitting
the exterior wires 14, 17 and 20 to exit for connection to a power
source.
A cylindrical spacer 24, which may also be comprised of ceramic
material, extends centrally through the annular support element 2
between the boss 25 and the end cap 4. The entire assembly is held
together, and the relative positions of the elements fixed, by a
retainer 31 in the form of heavy gauge square wire. The retainer 31
is swaged at one end 32 thereof. Elements 2, 4, 5, 10 and 24 of the
assembly 1 have a centrally disposed square bore for receiving the
retainer 31. The end cap 5 has a centrally disposed square bore 30,
the core 10 has a centrally disposed square bore 30, the end cap 4
has a centrally disposed square bore 28 and the boss 25 of the
annular support element 2 has a centrally disposed square bore 26.
The spacer 24 has a centrally disposed bore 27, which may be square
or circular, since it is not absolutely necessary to radially
restrain the spacer 24. A washer 33 is disposed between the swaged
end 32 of the retainer 31 and the end cap 5. The opposite free end
of the retainer 31 extends slightly beyond the boss 25 and has a
press fit retaining washer 34, such as a Tinnerman nut, forced
thereon. The washer 34 has a correspondingly shaped opening 40
therein and is slightly bowed such that once in place the edges of
the opening 40 provides sufficient friction against the retainer 31
so as to hold all of the elements together. The elements are thus
easily longitudinally fixed in relative position, and the square
cross section of the retainer 31 received in the respective square
bores simultaneously radially fixes the relative positions of the
elements. It will be understood that although the retainer 31 is
shown as having a square cross section, any polygonal cross section
which prevents radial rotation can be employed, such as a hex,
triangle, D-shape, or the like, the bores of the respective
components through which the retainer 31 extends being
correspondingly shaped.
The entire assembly 1 can thus be easily assembled without the
necessity of time-consuming adjustment of the various elements. The
coil 12 can be wound on the core 10 and the leads extending
therefrom easily inserted appropriately through the end cap 4,
after which all elements can be placed in succession on the
retainer 31 as shown in the exploded view of FIG. 3. The entire
assembly can then be appropriately inserted within the blower
device in which it is to be used.
Although modifications and changes may be suggested by those
skilled in the art it is the intention of the inventors to embody
within the patent warranted hereon all changes and modifications as
reasonably and properly come within the scope of their contribution
to the art.
* * * * *