Abstrict
An electric heater assembly is provided. The heater assembly includes
an electrically operable heating element and a pair of power leads
for supplying electrical power to the heating element. Each of the
power leads is connected to a respective end of the heating element
by a connector. A watertight seal is provided at the connection
of each power lead to the heating element. Each watertight seal
includes a sealing sleeve arranged over the respective connector
and a sealing compound provided between the sealing sleeve and the
respective connector. The heating element, the connectors and the
watertight seals are arranged in a housing. The housing includes
a pair of openings with each power lead extending through a respective
one of the pair of openings. Each of the openings has a rounded
smooth edge defined by a portion of the housing that is folded back
on itself.
Claims
1. An electric heater assembly comprising: an electrically operable
heating element; a pair of power leads for supplying electrical
power to the heating element, each power lead being connected to
a respective end of the heating element by a connector; a watertight
seal arranged at the connection of each power lead to the heating
element, each watertight seal comprising a sealing sleeve arranged
over the respective connector and a sealing compound provided between
the sealing sleeve and the respective connector; and a housing within
which the heating element, the connectors and the watertight seals
are arranged.
2. The electric heater assembly according to claim 1 wherein the
electric heater assembly is in the form of an elongated band.
3. The electric heater assembly according to claim 2 wherein the
housing is flexible.
4. The electric heater assembly according to claim 1 wherein the
heating element comprises a resistance wire helically wrapped around
a supporting core.
5. The electric heater assembly according to claim 4 wherein the
heating element includes a waterproof outer insulation layer.
6. The electric heater assembly according to claim 1 wherein the
housing comprises upper and lower housing portions that are assembled
along an unsealed joint.
7. The electric heater assembly according to claim 1 wherein the
housing includes a pair of openings with each power lead extending
through a respective one of the pair of openings and each of the
openings includes a rounded smooth edge defined by a portion of
the housing that is folded back on itself.
8. An electric heater assembly comprising: an electrically operable
heating element; a pair of power leads for supplying electrical
power to the heating element, each power lead being connected to
a respective end of the heating element; and a housing within which
the heating element and the connections of the heating element to
the power leads are arranged, the housing including a pair of openings
with each power lead extending through a respective one of the pair
of openings, each of the openings including a rounded smooth edge
defined by a portion of the housing that is folded back on itself,
each of the power leads extending past a respective one of the rounded
smooth edges.
9. The electric heater assembly according to claim 8 wherein the
electric heater assembly is in the form of an elongated band.
10. The electric heater assembly according to claim 9 wherein the
housing is flexible.
11. The electric heater assembly according to claim 8 wherein the
heating element comprises a resistance wire helically wrapped around
a supporting core.
12. The electric heater assembly according to claim 8 wherein the
housing comprises upper and lower housing portions and the folded
back portion of the housing is a portion of the upper housing portion.
13. An electric heater assembly comprising an electrically operable
heating element, a pair of power leads for supplying electrical
power to the heating element, each power lead being connected to
a respective end of the heating element, a watertight seal arranged
at the connection of each power lead to the heating element and
a housing within which the heating element, the connections of the
heating element to the power leads and the watertight seals are
arranged.
14. The electric heater assembly according to claim 13 wherein
the electric heater assembly is in the form of an elongated band.
15. The electric heater assembly according to claim 14 wherein
the housing is flexible.
16. The electric heater assembly according to claim 13 wherein
the heating element comprises a resistance wire helically wrapped
around a supporting core.
17. The electric heater assembly according to claim 16 wherein
the heating element includes a waterproof outer insulation layer.
18. The electric heater assembly according to claim 13 wherein
the housing comprises upper and lower housing portions that are
assembled along an unsealed joint.
19. The electric heater assembly according to claim 13 wherein
the housing includes a pair of openings with each power lead extending
through a respective one of the pair of openings and each of the
openings includes a rounded smooth edge defined by a portion of
the housing that is folded back on itself.
Description FIELD OF THE INVENTION
[0001] This invention pertains to electric heater assemblies.
BACKGROUND OF THE INVENTION
[0002] Electric heater assemblies having a strip or band like configuration
are used in a variety of different applications in which they are
exposed to moisture. For example, such heater assemblies are commonly
used in air conditioning units that are located outdoors. In particular,
the heater assembly is wrapped around the compressor of the air
conditioning unit in order to maintain the temperature of the liquid
and/or gas contained in the compressor at a predetermined elevated
level. Because of their outdoor location, the heater assemblies
are often exposed to adverse weather conditions such as rain, snow
and ice. In some cases, such as where the air conditioning unit
is installed near the ocean, the heater can be exposed to salt water.
Additionally, since the electric heater assembly is not always energized,
moisture can accumulate on the heater and freeze in cold weather
conditions.
[0003] This exposure to salt water, rain, snow or ice can lead
to problems with the electrical connections between the internal
resistive heating element of the electric heater assembly and the
power leads attached to the element. While waterproof and weather
resistant band type electric heater assemblies are known, they utilize
relatively bulky sealing structures that can make the heater assemblies
inconvenient to use such as by making it more difficult to form
the heater assembly into different shapes.
[0004] Another problem with band type electric band heater assemblies
is that during the handling and installation of the heater assembly,
the insulation of the power lead can be damaged, exposing the current
carrying strands of the power lead. The damage is caused when the
insulation of the power lead is inadvertently rubbed against the
sharp metal edge of the housing of the heater assembly. Obviously,
exposure of the current carrying strands of the power lead can lead
to a potentially dangerous electrical condition particularly in
applications where the heater assembly is exposed to moisture.
BRIEF SUMMARY OF THE INVENTION
[0005] The invention provides an improved electric heater assembly.
The heater assembly includes an electrically operable heating element
and a pair of power leads for supplying electrical power to the
heating element. Each of the power leads is connected to a respective
end of the heating element by a connector. A watertight seal is
provided at the connection of each power lead to the heating element.
Each watertight seal includes a sealing sleeve arranged over the
respective connector and a sealing compound provided between the
sealing sleeve and the respective connector. The heating element,
the connectors and the watertight seals are arranged in a housing.
[0006] In an alternative embodiment, the housing includes a pair
of openings with each power lead extending through a respective
one of the pair of openings. Each of the openings has a rounded
smooth edge defined by a portion of the housing that is folded back
on itself.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 is a perspective view of an exemplary electric heater
assembly in accordance with the present invention.
[0008] FIG. 2 is a plan view of the electric heater assembly of
FIG. 1 showing how the heater assembly can be equipped with clamping
hardware and formed into an illustrative circular shape.
[0009] FIG. 3 is a partial side view of the circular electric heater
assembly of FIG. 2.
[0010] FIG. 4 is a partially cut away plan view of a segment of
the heating element of the electric heater assembly of FIG. 1.
[0011] FIG. 5 is an exploded plan view of one power lead, an end
of the heating element and a barrel connector of the electric heater
assembly of FIG. 1.
[0012] FIG. 6 is a partially cut away plan view of the assembled
power lead, heating element and barrel connector of the electric
heater assembly of FIG. 1.
[0013] FIG. 7 is a plan view of the barrel connector crimped over
the corresponding ends of the power lead and the heating element
of the electric heater assembly of FIG. 1.
[0014] FIG. 8 is a plan view of an elastomeric sealing sleeve of
the electric heater assembly of FIG. 1.
[0015] FIG. 9 is a plan view of the elastomeric sealing sleeve
assembled over the barrel connector and the corresponding ends of
the power lead and heating element of the electric heater assembly
of FIG. 1.
[0016] FIG. 10 is a partially cutaway plan view of the elastomeric
sealing sleeve of the electric heater assembly of FIG. 1 showing
the elastomeric sleeve filled with a sealing compound.
[0017] FIG. 11 is a plan view showing the sealing sleeve assembled
over the barrel connector and the corresponding ends of the power
lead and heating element of the electric heater assembly of FIG.
1.
[0018] FIG. 12 is an exploded perspective view of the electric
heater assembly of FIG. 1 showing the assembly of the heating element
in the housing.
[0019] FIG. 13 is an exploded perspective view of the electric
heater assembly of FIG. 1 showing the upper housing portion being
assembled to the lower housing portion.
[0020] FIG. 14 is a perspective view of one end of an alternative
embodiment of an electric heater assembly according to the present
invention.
[0021] FIG. 15 is a perspective view of a flat blank used to form
the upper housing portion of the electric heater assembly of FIG.
16.
[0022] FIG. 16 is a perspective view of the upper portion of the
heater housing of the electric heater assembly of FIG. 16.
DETAILED DESCRIPTION OF THE INVENTION
[0023] Referring now to FIG. 1 of the drawings there is shown an
exemplary electric heater assembly 10 constructed in accordance
with the present invention. The illustrated electric heater assembly
10 is configured as an elongated flexible strip or band that can
be configured into a variety of shapes as desired to fit a specific
application. For example, as shown in FIGS. 2-3, the electric heater
assembly 10 can be formed into a circular shape that allows the
heater assembly 10 to be wrapped around an object to be heated so
as to provide conductive heat transfer from the heater assembly
to the object.
[0024] To facilitate mounting of the heater assembly 10, mounting
hardware such as clamping straps 12 can be attached to the heater
assembly as shown in FIGS. 2 and 3 to assist in clamping the heater
assembly tightly around the object to be heated, for example, an
air conditioning compressor. Of course, while the present invention
is described in connection with an electric heater assembly having
a band configuration, it will be readily appreciated that aspects
of the invention can be applied to electric heater assemblies having
different configurations.
[0025] For producing heat, the heater assembly 10 includes an electrically
powered heating element 14. As shown in FIG. 1, the illustrated
heating element 14 generally includes a resistance wire 16 that
is helically wrapped around the exterior surface of a cylindrical
core 18. The heating element 14 is heated by a flow of electrical
current through the resistance wire 16. As will be appreciated,
the resistance wire 16 can be made of any suitable electrically
conductive material such as, for example, nickel chromium. Moreover,
the core 18 can be made of any suitable electrically insulating
material such as, for example, fiberglass. To protect the heating
element 14 against moisture, the core 18 and resistance wire 16
are covered with a layer of a waterproof insulating material 20
such as an elastomeric material. Silicone rubber is one example
of a suitable elastomeric insulating material 20 for the heating
element 14.
[0026] The heater assembly 10 further includes a pair of power
leads 22 each of which connects to a respective one of the ends
of the heater assembly (see, e.g., FIG. 2) for supplying electric
power to the heating element 14. Each of the power leads 22 generally
consists of a plurality of internal conducting strands 24 that are
encased in a suitable insulating material such as PVC, silicone,
neoprene or Teflon.RTM.. To facilitate the connection of the power
leads 22 to the heating element 14, a length of the insulating material
on the power leads 22 is removed from an end of each of the power
leads, exposing the internal conducting strands 24 as shown with
respect to one end of the heater assembly 10 in FIG. 5. Likewise,
a short length of the insulation 20 is removed from the corresponding
ends of the heating element 14, revealing the internal resistance
wire 16 wrapped around the supporting core 18.
[0027] To connect the power leads 22 to the heating element 14,
the exposed resistance wire 16 and supporting core 18 at each end
of the heating element and the exposed conducting strands 24 of
the corresponding power lead 22 are inserted into either end of
a respective barrel connector 26 as shown with respect to one end
of the heater assembly 10 in FIGS. 5 and 6. In this case, the barrel
connector 26 consists of a length of appropriately sized metal tubing
having a circular cross-section. As shown in FIG. 7, the barrel
connector 26 is then crimped or compressed in order to grasp the
resistance wire 16 and supporting core 18 of the heating element
14 and the conducting strands 24 of the power lead 22. The compressed
barrel connector 26 mechanically holds the resistance wire 16 and
supporting core 18 of the heating element 14 and the conducting
strands 24 of the power lead 22 together as well as provides an
electrically conductive connection between the two.
[0028] In order to enable the electric heater assembly 10 to withstand
exposure to water and ice, the connections between the power leads
22 and the heating element 14 can incorporate watertight seals.
These watertight seals ensure that the connections between the power
leads 22 and the heating element 14 will retain their mechanical
and electrical integrity even when the heater assembly 10 is installed
in an outdoor application where it will be exposed to adverse weather
conditions including rain, snow and ice water or ice or installed
in an application where it will be submerged in water. To this end,
in the illustrated embodiment, each watertight seal includes a sealing
sleeve 28 (see FIG. 8) that can be arranged over the corresponding
barrel connector 26. As will be appreciated by those skilled in
the art, the sealing sleeves 28 can be made of any suitable elastomeric
material such as, for example, silicone rubber. Moreover, the sealing
sleeves 28 should have a length, diameter and wall thickness that
is suitable for the specific application in which the heater assembly
10 is to be used. In this case, each sealing sleeve 28 is slightly
longer than the corresponding barrel connector 26 such that it can
be positioned over the barrel connector with a portion of the sleeve
overlapping both the power lead 22 and the heating element 14 as
shown in FIG. 9 with respect to the connection of one of the power
leads. Additionally, the sealing sleeve 28 has an inside diameter
that allows it to fit snugly over the end of the heating element
14, the end of the power lead 22 or both.
[0029] To fill any voids underneath the sealing sleeve 28, a sealing
compound 30 can be injected or otherwise inserted into the space
between the inner wall of the sealing sleeve 28 and the compressed
barrel connector 26, the heating element 14 and the power lead 22
as shown in FIGS. 10 and 11 with respect to the connection of one
of the power leads. One example of a suitable method of delivering
the sealing compound 30 to the voids underneath the sealing sleeve
28 is using a syringe having a thin hypodermic needle that can fit
between the sealing sleeve and the power lead 22 or heating element
14. The snug fit between the sealing sleeve 28 and the power lead
22 and/or the heating element 14 can facilitate this delivery process.
In particular, the heater assembly 10 can be positioned vertically
with the snug section of the sealing sleeve 28 at the lowest point
so that the sealing compound 30 does not leak out of assembly while
the voids are being filled. Those skilled in the art will appreciate
that other techniques may be employed to fill the sealing sleeve
28 with the sealing compound 30.
[0030] The sealing compound 30 can consist of any suitable material
such as a room temperature vulcanization (RTV) sealing compound
or another curing rubber elastomer product. When cured, the sealing
compound should adhere to the outer insulation of the power lead
22 and the outer insulation of the heating element 14 such that
moisture cannot penetrate the sealed area to come in contact with
the electrical connection therebetween. The sealing compound 30
also should not breakdown, degrade, weaken, liquefy or otherwise
fail to provide an adequate seal when exposed to heat (e.g., when
the electric heater assembly 10 is energized) or cold (e.g., when
the electric heater assembly 10 is located outdoors).
[0031] In the illustrated embodiment, the heating element 14 and
power lead 22 assembly is contained within a housing 32 that facilitates
transfer of the heat produced by the heater assembly to the object
to be heated as well as formation of the heater assembly 10 into
different shapes. In this case, the housing 32 includes upper and
lower housing portions 34, 36 each of which is preferably constructed
of a heat conductive material that is sufficiently flexible so as
to permit the heater assembly 10 to be formed into different shapes.
In the unassembled state, as shown in FIG. 12, the illustrated lower
housing portion 36 has a pair of upstanding sidewalls 38 and a flat
bottom wall 40. The upper housing portion 34, in turn, includes
an axially extending recess or channel 42 that is shaped to conform
to the heating element 14 and power lead 22 assembly. This channel
or recess 42 has enlarged portions adjacent to either end that correspond
to the regions where the heating element 14 is connected to power
leads 22 via the barrel connectors 26 and associated watertight
seals.
[0032] The housing 32 is assembled by positioning the heating element
14 and power lead assembly 22 in the axially extending channel 42
in the upper housing portion 34 and arranging the upper housing
portion 34 such that it is resting on the flat bottom wall 40 of
the lower housing portion 36 between the upstanding sidewalls 38
as shown in FIGS. 12 and 13. The sidewalls 38 of the lower housing
portion 36 are then folded over the edges of the upper housing portion
34 to secure the upper and lower housing portions together and the
heating element/power lead assembly therebetween. The heater assembly
10 with the housing fully assembled is shown in FIG. 1. The assembled
housing 32 acts as a heat sink drawing heat away from the heating
element 14 and transferring it to the object to be heated through
the bottom wall 40 of the lower portion 36 of the housing. The broad,
flat configuration of the bottom wall 40 of the lower housing portion
36 facilitates this heat transfer process. Advantageously, the joint
between the upper and lower portions 34,36 of the housing does not
have to be watertight since the watertight seals provided at the
connections between the power leads 22 and the heating element 14
prevent water from reaching the electrically charged components
of the heater assembly 10.
[0033] An alternative embodiment of the present invention in which
the housing 32 is configured to prevent abrasion damage to the insulation
of the power leads 22 at the point at which the power leads exit
the housing is shown in FIGS. 14-16. The housings of band-type electric
heater assemblies are generally formed from a material such as sheet
metal that can present sharp edges. The insulation of the power
leads of the heater assembly can be cut or otherwise damaged if
it is repeatedly flexed or bent so as to rub against these sharp
metal edges. To eliminate the potential for damage to the insulation
of the power leads, the ends of the upper housing portion 34 can
be formed with smooth rounded edges 44 (see FIG. 14 which illustrates
one end of the housing). These smooth rounded edges 44 can be formed
by taking a short length of the metal edge of the upper housing
portion 34 and folding it back on itself. This moves the sharp edge
of the sheet metal away from the point at which the power lead 22
exits the housing 32 to a location where it cannot rub against the
power lead. Instead, a smooth rounded edge 44 is provided at the
point at which the power lead 22 exits the housing 14 so that if
the power lead is flexed or bent to rub against the edge such as
shown in FIG. 14, the insulation of the power lead will not be damaged.
[0034] The folded-back portion 46 can be produced by taking a flat
blank 48 that will be used to make the upper housing portion 34
and bending a desired length of the blank at each end of the blank
back onto itself. The bent back portion 46 is than flattened as
shown in FIG. 15 (illustrating one end of the blank). The axial
channel 42 for receiving the heating element and power lead assembly
is then formed into the blank, such as by using a die set or other
suitable method. One end of the completed upper housing portion
34 is shown in FIG. 16. It will be appreciated that the blank 48
for the upper housing portion 34 could be formed into any number
of final geometries depending on the needs of the application. While
the folded back housing edge aspect of the invention has been illustrated
with respect to a heater assembly having a watertight seal, this
aspect of the invention could be applied to heater assemblies that
do not include such a seal.
[0035] All references, including publications, patent applications,
and patents, cited herein are hereby incorporated by reference to
the same extent as if each reference were individually and specifically
indicated to be incorporated by reference and were set forth in
its entirety herein.
[0036] The use of the terms "a" and "an" and
"the" and similar referents in the context of describing
the invention (especially in the context of the following claims)
are to be construed to cover both the singular and the plural, unless
otherwise indicated herein or clearly contradicted by context. The
terms "comprising," "having," "including,"
and "containing" are to be construed as open-ended terms
(i.e., meaning "including, but not limited to,") unless
otherwise noted. Recitation of ranges of values herein are merely
intended to serve as a shorthand method of referring individually
to each separate value falling within the range, unless otherwise
indicated herein, and each separate value is incorporated into the
specification as if it were individually recited herein. All methods
described herein can be performed in any suitable order unless otherwise
indicated herein or otherwise clearly contradicted by context. The
use of any and all examples, or exemplary language (e.g., "such
as") provided herein, is intended merely to better illuminate
the invention and does not pose a limitation on the scope of the
invention unless otherwise claimed. No language in the specification
should be construed as indicating any non-claimed element as essential
to the practice of the invention.
[0037] Preferred embodiments of this invention are described herein,
including the best mode known to the inventors for carrying out
the invention. Variations of those preferred embodiments may become
apparent to those of ordinary skill in the art upon reading the
foregoing description. The inventors expect skilled artisans to
employ such variations as appropriate, and the inventors intend
for the invention to be practiced otherwise than as specifically
described herein. Accordingly, this invention includes all modifications
and equivalents of the subject matter recited in the claims appended
hereto as permitted by applicable law. Moreover, any combination
of the above-described elements in all possible variations thereof
is encompassed by the invention unless otherwise indicated herein
or otherwise clearly contradicted by context. |