SHEATHED FIBERGLASS HEATER WIRE

Abstract

An apparatus is disclosed. The apparatus includes a resistive wire having a circumference. The apparatus further includes a first fiberglass layer disposed about the circumference of the resistive wire and along a length of the resistive wire. The apparatus further includes a second fiberglass layer. The apparatus further includes a third fiberglass layer, the second fiberglass layer disposed between the first fiberglass layer and the third fiberglass layer, the third fiberglass layer forming an outer layer and surrounding the second fiberglass layer.

Description

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. application Ser. No. 15/880,417, filed Jan. 25, 2018, entitled “Sheathed Fiberglass Heater Wire,” the contents of which is fully incorporated by reference in its entirety.

TECHNICAL FIELD

The subject matter described herein relates to a heater apparatus used in electric appliances such as a refrigerator.

BACKGROUND

A variety of electrical appliances may incorporate a heating apparatus to prevent frost from forming, to evaporate moisture, to prevent freezing of components, etc. For example, a refrigerator often includes a freezer compartment, a refrigerator compartment, and a cooling portion. The cooling portion may provide cold air, via circulation of a refrigerant, to the freezer and refrigerator compartments. The cooling portion may also include one or more heaters to help manage temperature of the different compartments, defrost components or compartments, prevent freezing, etc.

Additionally, the refrigerator may include various electrical components such as various temperature sensors for detecting temperatures of various compartments provided in the refrigerator and detecting completion of defrosting, a fan that blows air to the respective compartments, and a damper for adjusting the amount of cold air blow are arranged in the refrigerator. These electrical components can be connected to a control substrate set up inside or outside the refrigerator via lead wires.

In some systems, the heater wires and/or lead wires may be exposed to a leaked refrigerant. Typical refrigerants have a relatively low ignition point and are flammable. Often heater wires and/or lead wires may operate at a surface temperature that could surpass the ignition point of the leaked refrigerant. Accordingly, it may be beneficial for improved heater wires and/or lead wires that maintain a low surface temperature.

SUMMARY

Apparatus, systems and methods for controlling the temperature of a heating element are disclosed.

In a first aspect, an apparatus includes a resistive wire having a circumference. The apparatus further includes a first fiberglass layer disposed about the circumference of the resistive wire and along a length of the resistive wire. The apparatus further includes a second fiberglass layer. The apparatus further includes a third fiberglass layer. The second fiberglass layer is disposed between the first fiberglass layer and the third fiberglass layer. The third fiberglass layer forms an outer layer and surrounds the second fiberglass layer.

In an interrelated aspect, a method is disclosed. The method includes providing a heater wire disposed within a tube of a refrigeration system. The heater wire includes a resistive wire having a circumference. The heater wire further includes a first fiberglass layer disposed about the circumference of the resistive wire and along a length of the resistive wire. The heater wire further includes a second fiberglass layer. The heater wire further includes a third fiberglass layer, the second fiberglass layer disposed between the first fiberglass layer and the third fiberglass layer, the third fiberglass layer forming an outer layer and surrounding the second fiberglass layer. The method further includes providing a current through the resistive wire to heat at least a portion of the refrigeration system.

In some variations one or more of the following features can optionally be included in any feasible combination. The apparatus or heater wire may also include a fiberglass core, the resistive wire wound about the fiberglass core. The first fiberglass layer can comprise an S-glass type fiberglass. The apparatus or heater wire may also include a polyimide layer, the polyimide layer forming an outer layer and surrounding the third fiberglass layer.

The details of one or more variations of the subject matter described herein are set forth in the accompanying drawings and the description below. Other features and advantages of the subject matter described herein will be apparent from the description and drawings, and from the claims. While certain features of the currently disclosed subject matter are described for illustrative purposes in relation to particular implementations, should be readily understood that such features are not intended to be limiting. The claims that follow this disclosure are intended to define the scope of the protected subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute a part of this specification, show certain aspects of the subject matter disclosed herein and, together with the description, help explain some of the principles associated with the disclosed implementations. In the drawings,

FIG. 1 is a cross-sectional diagram illustrating an exemplary embodiment of a heater wire, in accordance with certain aspects of the present disclosure;

FIG. 2 is a side view of the heater wire, in accordance with certain aspects of the present disclosure;

FIG. 3 is a cross-sectional diagram illustrating an exemplary embodiment of a heater wire, in accordance with certain aspects of the present disclosure;

FIG. 4A is a schematic diagram of an exemplary embodiment of a heater wire and a lead wire, in accordance with certain aspects of the present disclosure;

FIG. 4B is a cross-sectional diagram illustrating an exemplary embodiment of a heater wire, in accordance with certain aspects of the present disclosure;

FIG. 5 is schematic diagram of an exemplary embodiment of a heater wire and a lead wire, in accordance with certain aspects of the present disclosure; and

FIG. 6 is schematic diagram of an exemplary embodiment of a heater wire and a lead wire, in accordance with certain aspects of the present disclosure.

DETAILED DESCRIPTION

Appliance systems, like refrigerators, often incorporate heaters to control temperatures within the appliance system. For example, it may be desirable for the refrigerator to incorporate heaters to regulate temperature in various compartments to prevent unwanted freezing, condensation, or frost accumulation. The heaters may radiate heat from heater wires which receive power/current from lead wires within the refrigerator system. Often these wires may be placed near tubes or components that contain flammable refrigerants.

In the conventional systems, however, the surface temperature of tubes housing the heater and/or lead wires may increase during operation. In some cases, it is possible that the surface temperature rises high, possibly exceeding the ignition point of the flammable refrigerant. For example, refrigerant R600a (Isobutane) has an ignition temperature of 460° C. Hence, when the flammable refrigerant is used, it is beneficial that the heater/lead wires, and tubes containing the wires, never be a source of ignition of leaked refrigerants due to supply of power through the wires. Common insulation tubes used for the heater/lead wires include neoprene or double wall heat shrink tubing. Embodiments described herein relate to improved systems and wire configurations that would reduce the threat of ignition in such cases.

For example, it may be beneficial to design a system where the surface temperature of parts that may be exposed to a leaked refrigerant may not exceed the ignition temperature of the refrigerant (e.g., 460° C. for R600a) reduced by 100° C. (e.g., 360° C.). In some aspects, the system may be designed such that a maximum working surface temperature does not exceed 300° C. for the heater. Additionally, the system and the heating/lead wires may also have to comply with other requirements (e.g., energy efficiency requirements or size constraints). In some cases, the heater/lead wires may be configured to withstand a surge test procedure or satisfy other tests required for certification, approval, etc.

FIG. 1 is a cross-sectional diagram illustrating an exemplary embodiment of a heater wire 100 for use in a refrigeration system, in accordance with certain aspects of the present disclosure. As shown in FIG. 1, the heater wire 100 comprises a fiberglass core 102, a resistive wire 104 wound around the fiberglass core 102, a first fiberglass layer 106, a second fiberglass layer 108, and a third fiberglass layer 110. As illustrated, the first fiberglass layer 106 is located between the resistive wire 104 and the second fiberglass layer 108, the second fiberglass layer 108 is located between the first fiberglass layer 106 and the third fiberglass layer 110, and the third fiberglass layer 110 is the outer layer with its inner surface coupled to the second fiberglass layer 108. While three fiberglass layers are shown in FIG. 1, more or fewer fiberglass layers are also possible. For example, the heater wire 100 can comprise four or five fiberglass layers to increase a total diameter of the heater wire 100. In some aspects, the heater wire 100 may also be used as a lead wire. In some implementations, the resistive wire 104 may comprise a nickel-chromium wire (e.g., 80-20 NiCr), any iron, copper, or aluminum-based wire alloy, or any other suitable resistive wire. In some aspects, the resistive wire 104 can comprise a single or double resistance wire. In other aspects, the resistive wire 104 can comprise three or more wires.

In some aspects, the fiberglass material used for the fiberglass core 102 and the fiberglass layers 106, 108, and 110 may comprise the same or different fiberglass material. For example, the fiberglass core 102 and the first fiberglass layer 106 may comprise a first fiberglass material and the second and third fiberglass layers 108 and 110 may comprise a second fiberglass material. Additionally, each of the fiberglass core 102 and the fiberglass layers 106, 108, and 110 may comprise different fiberglass material, or any combination of fiberglass material. In some embodiments, the fiberglass material may comprise an S-glass type fiberglass.

FIG. 2 is a side view of the heater wire 100, in accordance with certain aspects of the present disclosure. As shown in FIG. 2, the resistive wire 104 wrapped around the fiberglass core 102 may have a first diameter θ₁ and the entire heater wire 100 and the third fiberglass layer may have a second diameter θ₂. The second diameter θ₂ larger than the first diameter θ₁. In some aspects, the second diameter θ₂ comprise a diameter of 3.8-3.9 mm. In some embodiments the second diameter θ₂ may configured to fit within a tube of the refrigerator or refrigeration system.

The heater wire 100 configuration may allow improved safety and performance within a refrigeration system. The heater wire 100 may exhibit increased ability to withstand high voltages compared to conventional heater wires. For example, the heater wire 100 may be configured to withstand a high potential (HIPOT) of up to 1500V. Additionally, the heater wire 100 may also withstand a surge test at 2000V without failure. The heater wire 100 may also exhibit reduced leakage current and greater insulation resistance compared to conventional heater wires. In some aspects, the heater wire 100 can be configured to exhibit a leakage current of less than 0.07 mA. The heater wire 100 can also exhibit an insulation resistance of greater than 2 GΩ. Such properties demonstrate an improved performance of heater wires used within conventional refrigeration systems.

FIG. 3 is a cross-sectional diagram illustrating an exemplary embodiment of a heater wire 300 for use in a refrigeration system, in accordance with certain aspects of the present disclosure. As shown in FIG. 3, the heater wire 300 comprises a fiberglass core 302, a resistive wire 304 wound around the fiberglass core 302, a first fiberglass layer 306, a second fiberglass layer 308, a third fiberglass layer 310, and a polyimide layer 312.

As illustrated, the first fiberglass layer 306 is located between the resistive wire 304 and the second fiberglass layer 308, the second fiberglass layer 308 is located between the first fiberglass layer 306 and the third fiberglass layer 310, the third fiberglass layer 310 is located between the second fiberglass layer 308 and the polyimide layer 312, and the polyimide layer 312 is the outer layer of the heater wire 300 with its inner surface in contact with the third fiberglass layer 310. In some aspects, the heater wire 300 may also be used as a lead wire. In some embodiments, one or more of the fiberglass core 302, resistive wire 304, first fiberglass layer 306, second fiberglass layer 308, third fiberglass layer 310 may comprise the same or different material as the fiberglass core 102, resistive wire 104, and the fiberglass layers 106, 108, and 110 of the heater wire 100 of FIG. 1. While two fiberglass layers are shown in FIG. 3, other numbers of fiberglass layers are also possible. For example, the heater wire 300 can comprise three or more fiberglass layers to increase a total diameter of the heater wire 300.

In some implementations, the polyimide layer 312 may comprise a tape of a polyimide film and silicone adhesive that is designed for high temperature masking applications, including the protection of printed circuit board gold finger contacts during wave soldering. The polyimide layer 312 may beneficially increase the dielectric insulation capability of the heater and the heater wire 300. This may also increase the protection against unsafe failure during operation. In some implementations, the polyimide layer 312 can comprise one or more layers. For example, the polyimide layer 312 can comprise two or more polyimide layer which can increase the total diameter of the heater wire 300.

For example, the heater wire 300 may exhibit increased ability to withstand high voltages compared to conventional heater wires and the heater wire 100. In some aspects, the heater wire 300 can be configured to withstand a surge test at 4000V without failure. The heater wire 300 may also exhibit reduced leakage current and greater insulation resistance compared to conventional beater wires and the heater wire 100.

In some aspects, the heater wires 100 and/or 300 are implemented in a refrigeration system. While embodiments described below apply to the heater wire 300, they may also apply to the heater wire 100. In the refrigeration system, the heater wire 300 may be connected to a power supply through lead wires. In some aspects, the power supply may comprise a battery, a wall power outlet, or another voltage/current supply. In some aspects, the heater wire 300 may be disposed within a tube of the refrigeration system. The tube may comprise a stainless steel tube, neoprene tube, a double wall heat shrink tube, a fiberglass tube, a glass tube, or any other suitable tubing.

As the power supply provides current through the heater wire 300, the heater wire 300 generates heat. A portion of that heat can be transferred to the tubing surrounding the heater wire 300, and the surface of the tubing can rise to a temperature less than the ignition point of the flammable refrigerant, thereby defrosting the peripheral parts. In some aspects, the heater wire 300 may also be configured to provide heat to evaporate moisture within the refrigeration system prevent frost from forming, and/or to prevent freezing of components of the refrigeration system.

In the event of a flammable refrigerant leaking in an area around the heater wire 300, the configuration of the heater wire 300 may beneficially keep the surface temperature of the heater wire 300, and any tube containing the heater wire 300, below the ignition point of the flammable refrigerant. As noted above, in some aspects, the heater wire 300 may be configured to have a maximum surface temperature at least 100° C. below the ignition point of the refrigerant. Hence, even if there is flammable refrigerant around the heater wire 300, accidents due to surface temperatures exceeding the ignition point can be prevented.

In some implementations, the heater wire 300 may be coupled with a lead wire 400 at an end 350 of the heater wire 300. For example, the end 350 of the heater wire 300 may be coupled with the lead wire as shown in FIGS. 4A and 4B, within a seal 402, such as a neoprene seal. As the heater wire 300 is coupled with the lead wire 400 at the end of the heater wire 300, outside of the tubing surrounding the heater wire 300, one or more (e.g., two, three or more) lead wires may contact an end of the resistive wire 304, or extend along a length of the heater wire 300. The lead wires 400 supply current to the resistive wire 304 of the heater wire 300 by contacting at least a portion of the heater wire 300, such as at each of the winds of the restive wire 304, or an end of the resistive wire 304.

In some implementations, an unheated or reduced temperature zone (e.g., a cold zone) may be desired along an end portion (e.g., the end 350) of the heater wire 300 at or along a portion of the heater wire 300 that connects with the lead wire 400. The cold zone may be desired to reduce the likelihood of a fire, break in connection, overheating of the junction between the heater wire and the lead wire, and the like. To form the cold zone, one or more wires 320 (e.g., metal wires) may extend along the fiberglass core 302 and contact a portion of the resistive wire 304, such as at the winds of the resistive wire coil (see, e.g., FIG. 4B). The contact between the wires 320 and the resistive wire 304 creates a short circuit, limiting or reducing the temperature at the regions of contact. In some implementations, the wires 350 may separate from the resistive wire 304, as the wires 350 may become entangled with the fibers of the fiberglass core 302. Thus, it may be beneficial for the lead wires 400 to be crimped directly to the resistive wire 304.

Directly coupling the lead wire 400 with the resistive wire 304 can help to ensure that any desired cold zones along the heater wire 300 remain at the desired temperature, and may help to reduce the length of the cold zone. For example, the lead wire 400 may be coupled with the resistive wire 304 over the regions where the cold zone is desired (see FIGS. 5 and 6), at or adjacent to an end of the cold zone, where it is desired for the heater wire to be heated. This configuration helps to ensure that the heat caused by the resistive wire 304 does not pass to the cold zone of the heater wire 300, so that the temperature of the cold zone of the heater wire 300 remains below the ignition point of the leaked refrigerant, for example.

FIGS. 5 and 6 illustrate examples of the lead wires 400 crimped directly to the resistive wire 304, consistent with implementations of the current subject matter. For example, FIG. 5 illustrates an example of the lead wire 400 directly coupled with the resistive wire 304. Here, the lead wire 400 may not contact the fiberglass core 302. FIG. 6 illustrates an example of the lead wire 400 directly coupled with the resistive wire 304, and at least a portion of the fiberglass of the heater wire 300 (e.g., the fibers of the fiberglass core 302). Coupling the lead wire 400 with the resistive wire 304 and fibers of the fiberglass material may help to strengthen the junction between the lead wire 400 and the heater wire 300. The lead wires 400 may include neoprene or other materials. The direct connection between the resistive wire 304 and the lead wires 400 help to maintain consistent contact between the lead wires 400 and the resistive wire 304.

As shown in FIGS. 5 and 6, the lead wire 400 is coupled with the resistive wire 304 within the heater wire 300, and external to the seal (e.g., neoprene seal). Thus, the thickness and/or circumference of the neoprene seal may be reduced. The heater wire 300 may also be more easily be assembled, and be implemented in other heating applications that have limited available space and thus may require a reduced seal size or reduced overall wire circumference. In some implementations in which the heater wire 300 is coupled with the lead wire 400 within the seal 402 and external to the heater wire 300, the seal may not be well-formed, or may crack, exposing the junction between the heater wire 300 and the lead wire 400. Exposing the junction between the heater wire 300 and the lead wire 400 may allow unwanted humidity to develop around the resistive wire 304 or undesirably increase the likelihood of a fire, or a break in the connection between the lead wire 400 and the heater wire 300. Thus, coupling the lead wire 400 with the resistive wire 304 within the heater wire (e.g., within the tube surrounding the heater wire) and adjacent to or external to the seal 402 may provide an enhanced boundary to limit or prevent humidity from entering the heater wire 300. Furthermore, the material of the lead wire 400 (e.g., neoprene) may vulcanize with the material of the seal 402 (e.g., neoprene) to enhance the sealing effect.

In some implementations, the connection between the heater wire 300 and the lead wire 400 is insulated using an isolation material 406. The isolation material 406 may be designed for high temperature masking applications, including the protection of printed circuit board gold finger contacts during wave soldering. The isolation material may include polyimide (which may include a tape of a polyimide film and silicone adhesive), fiberglass, a combination of polyimide tape and fiberglass tape, and the like.

A person skilled in the art will appreciate that, while the methods, systems, and devices are disclosed herein for heater and/or lead wires in a refrigeration system, the methods, systems, and devices can be used in a variety of other electrical appliances, components, and systems.

In the descriptions above and in the claims, phrases such as “at least one of” or “one or more of” may occur followed by a conjunctive list of elements or features. The term “and/or” may also occur in a list of two or more elements or features. Unless otherwise implicitly or explicitly contradicted by the context in which it used, such a phrase is intended to mean any of the listed elements or features individually or any of the recited elements or features in combination with any of the other recited elements or features. For example, the phrases “at least one of A and B;” “one or more of A and B;” and “A and/or B” are each intended to mean “A alone, B alone, or A and B together.” A similar interpretation is also intended for lists including three or more items. For example, the phrases “at least one of A, B, and C;” “one or more of A, B, and C;” and “A, B, and/or C” are each intended to mean “A alone, B alone, C alone, A and B together, A and C together, B and C together, or A and B and C together.” Use of the term “based on,” above and in the claims is intended to mean, “based at least in part on,” such that an unrecited feature or element is also permissible.

The subject matter described herein can be embodied in systems, apparatus, methods, computer programs and/or articles depending on the desired configuration. Any methods or the logic flows depicted in the accompanying figures and/or described herein do not necessarily require the particular order shown, or sequential order, to achieve desirable results. The implementations set forth in the foregoing description do not represent all implementations consistent with the subject matter described herein. Instead, they are merely some examples consistent with aspects related to the described subject matter. Although a few variations have been described in detail above, other modifications or additions are possible. In particular, further features and/or variations can be provided in addition to those set forth herein. The implementations described above can be directed to various combinations and subcombinations of the disclosed features and/or combinations and subcombinations of further features noted above. Furthermore, above described advantages are not intended to limit the application of any issued claims to processes and structures accomplishing any or all of the advantages.

Additionally, section headings shall not limit or characterize the invention(s) set out in any claims that may issue from this disclosure. Specifically, and by way of example, although the headings refer to a “Technical Field,” such claims should not be limited by the language chosen under this heading to describe the so-called technical field. Further, the description of a technology in the “Background” is not to be construed as an admission that technology is prior art to any invention(s) in this disclosure. Neither is the “Summary” to be considered as a characterization of the invention(s) set forth in issued claims. Furthermore, any reference to this disclosure in general or use of the word “invention” in the singular is not intended to imply any limitation on the scope of the claims set forth below. Multiple inventions may be set forth according to the limitations of the multiple claims issuing from this disclosure, and such claims accordingly define the invention(s), and their equivalents, that are protected thereby.

Claims

1. An apparatus comprising:

a resistive wire having a circumference;

a first fiberglass layer disposed about the circumference of the resistive wire and along a length of the resistive wire;

a second fiberglass layer; and

a third fiberglass layer, the second fiberglass layer disposed between the first fiberglass layer and the third fiberglass layer, the third fiberglass layer forming an outer layer and surrounding the second fiberglass layer.

2. The apparatus of claim 1, further comprising a fiberglass core, the resistive wire wound about the fiberglass core.

3. The apparatus of claim 1, wherein the first fiberglass layer comprises an S-glass type fiberglass.

4. The apparatus of claim 1, wherein the first fiberglass layer comprises a fiberglass material different than a fiberglass material of the second fiberglass layer.

5. The apparatus of claim 2, wherein the fiberglass core comprises an S-glass type fiberglass.

6. The apparatus of claim 1, wherein the third fiberglass layer comprises a fiberglass material different than the first fiberglass layer and different than the second fiberglass layer.

7. The apparatus of claim 1, further comprising a polyimide layer, the polyimide layer forming an outer layer and surrounding the third fiberglass layer.

8. The apparatus of claim 7, wherein the polyimide layer comprises a polyimide film and silicone adhesive.

9. The apparatus of claim 1, further comprising a lead wire crimped onto the resistive wire, the lead wire configured to supply a current to the resistive wire.

10. A method comprising:

providing a heater wire disposed within a tube of a refrigeration system, the heater wire comprising: a resistive wire having a circumference; a first fiberglass layer disposed about the circumference of the resistive wire and along a length of the resistive wire; a second fiberglass layer; and a third fiberglass layer, the second fiberglass layer disposed between the first fiberglass layer and the third fiberglass layer, the third fiberglass layer forming an outer layer and surrounding the second fiberglass layer; and

providing a current through the resistive wire to heat at least a portion of the refrigeration system.

11. The method of claim 10, wherein the heater wire further comprises a fiberglass core, the resistive wire wound about the fiberglass core.

12. The method of claim 10, wherein the first fiberglass layer comprises an S-glass type fiberglass.

13. The method of claim 10, wherein the first fiberglass layer comprises a fiberglass material different than a fiberglass material of the second fiberglass layer.

14. The method of claim 11, wherein the fiberglass core comprises an S-glass type fiberglass.

15. The method of claim 10, wherein the third fiberglass layer comprises a fiberglass material different than the first fiberglass layer and different than the second fiberglass layer.

16. The method of claim 10, wherein the heater wire further comprises a polyimide layer, the polyimide layer forming an outer layer and surrounding the third fiberglass layer.

17. The method of claim 16, wherein the polyimide layer comprises a polyimide film and silicone adhesive.

18. The method of claim 10, wherein the current is provided via a lead wire crimped onto the resistive wire.