Source: https://patents.google.com/patent/JP3669635B2/en
Timestamp: 2020-02-26 20:35:08
Document Index: 252919414

Matched Legal Cases: ['art 300', 'art 300', 'art 300', 'art 300', 'art 300', 'art 300', 'art 300', 'art 300']

JP3669635B2 - Polymer resistance heating element - Google Patents
Polymer resistance heating element Download PDF
JP3669635B2
JP3669635B2 JP52113996A JP52113996A JP3669635B2 JP 3669635 B2 JP3669635 B2 JP 3669635B2 JP 52113996 A JP52113996 A JP 52113996A JP 52113996 A JP52113996 A JP 52113996A JP 3669635 B2 JP3669635 B2 JP 3669635B2
JP52113996A
JPH10512089A (en
エックマン、チャールズ・エム
エナジー・コンバーターズ・インク
リーム・マニュファクチュアリング・カンパニー
1995-12-28 Application filed by エナジー・コンバーターズ・インク, リーム・マニュファクチュアリング・カンパニー filed Critical エナジー・コンバーターズ・インク
1995-12-28 Priority to PCT/US1995/016928 priority patent/WO1996021336A1/en
1998-11-17 Publication of JPH10512089A publication Critical patent/JPH10512089A/en
2005-07-13 Publication of JP3669635B2 publication Critical patent/JP3669635B2/en
FIELD OF THE INVENTION The present invention relates to electrical resistance heating elements, and more particularly to polymer-based resistance heating elements for heating gases and liquids.
BACKGROUND OF THE INVENTION Electrical resistance heating elements used in connection with water heaters have traditionally been made of metal and ceramic components. A typical structure includes a pair of terminal pins brazed to both ends of a nickel chrome coil. The nickel chrome coil is disposed in the axial direction inside a U-shaped tubular metal sheath. The resistance coil is usually insulated from the metal sheath by a powdered ceramic material such as magnesium oxide.
Such conventional heating elements have been the main product of the water heater industry for the last 10 years, but have had widely recognized defects. For example, the electrochemical current generated between the metal sheath and the exposed metal surface in the tank causes corrosion to various anodic metal components of the system. The metal sheath of the heating element is typically copper or a copper alloy, but adsorbs lime deposits from water, causing premature failure of the heating element. In addition, brass fittings and copper piping were used, which led to high costs due to years of rising copper prices.
At least one plastic sheath electric heating element is disclosed in US Pat. No. 3,943,328 as an alternative to a metal element. In the disclosed device, a conventional resistance wire and powdered magnesium oxide are used with a plastic sheath. This plastic sheath is non-conductive and does not form a chemical cell with other metal parts of the heating unit that are in contact with water in the tank, nor does it produce coal deposits. However, this prior art plastic sheath heating element has not been widely used because it cannot achieve high watt ratings beyond its normal useful life.
SUMMARY OF THE INVENTION The present invention provides a polymer electrical resistance heating element and a water heater including such element. Preferred elements include a conductive resistive heating member having a pair of free ends coupled to a pair of ends. The resistance heating member is hermetically insulated in an integral layer of polymer members. Both the resistive member and the polymer layer generate the heat of the new heating element. The heating element provides sufficient resistance heating to heat a quantity of water to a temperature of at least about 49 ° C. (120 ° F.) without melting the polymer layer.
The heating element of the present invention is most suitable for heating commercial and residential hot water. The heating element is at least about 100-1200 watts ("W") for heating the gaseous fluid medium, at least about 1000 to 6000 watts ("W") for heating the liquid fluid medium, preferably Generate 1700-4500W. This power can be generated without damaging the polymer coating or storage tank of the water heater, for example, even if the tank is made of plastic. The present invention is not limited to any particular theory, but the cooling effect of the fluid medium, i.e. oil, air, or water, keeps the polymer layer below its melting point, thus melting the convective heat from the resistance heating member. It seems to communicate without.
In order to efficiently heat the water to a practical temperature of about 49 ° C.-82 ° C. (120 ° F.-180 ° F.), the polymer coating is as thin as possible, preferably 1.27 cm (0.5 inch), Ideally it should be 0.25 cm (0.1 inch). As a result, the coating blocks the electrical short circuit in an airtight manner without having a mass that impairs the heat transfer efficiency of the element. The polymer coating is uniform and substantially free of bubbles to prevent the generation of hot spots along the element leading to premature failure in the liquid environment.
An electrical resistance heating element used to heat the fluid medium in a more detailed embodiment of the present invention is described. The heating element includes a bent resistance wire helical coil having a pair of free ends.
The helical coil is encapsulated in a heat resistant polymer. The element is tubular with an open end and a closed end. The closed end consists of a threaded flange connector and at least one pair of conductors connected to the free end of the resistance wire and extending from the threaded flange connector outside the element to connect to an external power source. The heating element further includes a heat-resistant shut-off device that interrupts the electrical energy flowing through the element upon occurrence of overheating, polymer melting, or electrical shorting.
The accompanying drawings illustrate preferred embodiments of the invention as well as other information relevant to the present disclosure.
FIG. 1 is a perspective view of a preferred polymer fluid heater of the present invention.
FIG. 2 is a front view of the left side of the polymer fluid heater of FIG.
FIG. 3 is a partial sectional view of the polymer fluid heater of FIG. 1 and includes a front view including a partially peeled drawing.
FIG. 4 is a front view and a partial sectional view of a preferred internal molding part of the polymer fluid heater of FIG.
FIG. 5 is a front view and partial cross-sectional view of a preferred termination assembly for the polymer fluid heater of FIG.
FIG. 6 is an enlarged partial front view of the end of a preferred coil for the polymer fluid heater of the present invention.
FIG. 7 is an enlarged partial front view of an embodiment of a double coil for the polymer fluid heater of the present invention.
DETAILED DESCRIPTION OF THE INVENTION The present invention provides an electrical resistance heating element and a water heater including this element. These devices are useful in solving the problems of chemical cell corrosion of water and oil heaters, lime deposition and shortening of element life. As used herein, the terms “fluid” and “fluid medium” apply to both liquids and gases.
The preferred polymer fluid heater 100 of the present invention is shown in the drawings, particularly in FIGS. The polymer fluid heater 100 includes a conductive resistance heating member. This may be, for example, a wire, a mesh, a ribbon, or a winding shape. A preferred heater 100 is provided with a coil 14 having a pair of free ends connected to a pair of terminals 12 and 16 for generating resistance heat. The coil 14 is an integral layer of heat resistant polymer that is hermetically insulated from the fluid. That is, the active resistance heating member is protected from short circuits in the fluid by the polymer coating. The resistive member of the present invention has a surface area, length and cross-sectional thickness sufficient to heat water to a temperature of at least about 49 ° C. (120 ° F.) without the polymer layer melting. This can be achieved by careful selection of the correct members and their dimensions, as will be apparent from the following description.
In particular, FIG. 3 shows a preferred polymer fluid of the present invention which generally comprises three integral parts, namely the termination assembly 200 shown in FIG. 5, the inner mold 300 shown in FIG. 4, and the polymer coating 30. A heater 100 is shown. Each of these components and the final assembly into the polymer fluid heater 100 are described below.
The preferred internal molding part 300 shown in FIG. 4 is a single injection molding component made of a heat resistant polymer. The inner molded part 300 is preferably provided with a flange 32 at the end. A collar portion having a plurality of screws 22 is provided adjacent to the flange 32. The screw 22 is designed to fit within the inner diameter of a mounting hole through the side wall of a storage tank, for example a water heater tank. An O-ring (not shown) may be used on the inner surface of the flange 32 to provide a high water tight seal. The preferred inner mold 300 further includes a thermistor cavity 39 located within its preferred annular cross section. The thermistor cavity 39 may include an end wall 33 for separating the thermistor 25 from the fluid. The thermistor cavity 39 may open through the flange 32 to allow easy insertion of the termination assembly 200. A preferred inner mold 300 is also located between the thermistor cavity and the inner mold, and includes at least one pair of conductor cavities 31 and 35 for receiving the conductor bar 18 and terminal conductor 20 of the termination assembly 200. including. The inner molding portion 300 includes a plurality of grooves 38 arranged in parallel in the radial direction on the outer circumference thereof. These grooves can be made of threads or the like and should have sufficient spacing to form a seat for electrically separating the coil 14 windings.
A preferable internal molding part 300 can be manufactured by an injection molding method. The through-cavity 11 is preferably manufactured with a hydraulically actuated core that is 31.75 cm (12.5 inches) in length, thereby producing an element that is 13-18 inches in length. The inner molded part 300 is filled in a metal mold using an annular gate placed directly opposite the flange 32. The target wall thickness for the active element 10 is preferably less than 0.5 inches and preferably 0.14 inches. And the target range is preferably 0.14-0.15 cm (0.04-0.06 inches), which is believed to be the current lower limit for injection molding equipment. A pair of hooks or pins 45 and 55 are formed along the active element 10 between successive threads to form termination points or anchors for one or more coil windings. doing. During injection molding, thermistor cavities 39, through cavities 11, conductor cavities 31 and 35, and through holes 57 can be formed using side core centering and end cores that pass through the flange.
A preferred termination assembly 200 will be described with reference to FIG. Termination assembly 200 comprises a polymer end cap 28 designed to receive a pair of terminal connections 23 and 24. As shown in FIG. 2, the terminal connections 23 and 24 may include screw holes 34 and 36 for receiving screw connectors such as screws for attaching external wires. The terminal connection portions 23 and 24 are terminal portions of the terminal conductor 20 and the thermistor conductor bar 21. The thermistor conductor bar 21 connects the terminal connection portion 24 to the thermistor terminal 27. The other thermistor terminal 29 is designed to fit inside the conductor cavity 35 and is connected to the thermistor conductor bar 18 along the lower portion of FIG. A thermistor 25 is provided to configure the circuit. The thermistor 25 can be arbitrarily replaced with a thermostat, a solid state TCO, or simply a circuit breaker. During the melting of the polymer, it appears that a grounding band (not shown) can be shorted by being positioned in close proximity to one of the terminal ends 16 or 12.
In a preferred environment, the thermistor 25 is a snap action thermostat or thermo protector such as the model W series sold by Portage Electric. This thermoprotector has a small size, is adapted for 120 or 240 volt loads and has a conductive bimetal structure with an electroactive case. The end cap 28 is preferably part of a separate molded polymer.
After the termination assembly 200 and the internal molded portion 300 are manufactured, the assembly 200 and the internal molded portion 300 may be assembled before the coil 14 exposed on the alignment groove 38 of the active element portion 10 is wound. Care should be taken to construct the completed circuit including the coil terminals 12 and 16. This is accomplished by brazing, soldering, or spot welding the coil ends 12 and 16 to the terminal conductor 20 and the thermistor conductor bar 18. It is also important that the coil 14 be correctly positioned on the inner molded part 300 before applying the polymer coating 30. In the preferred embodiment, the polymer coating 30 is extruded over the inner mold to form a thermoplastic polymer bond with the inner mold 300. As with the internal molding section 300, centering can be introduced into the mold during the molding process to keep the through hole 57 and the through cavity 11 open.
Referring to FIGS. 6 and 7, examples of single and multiple resistance wires for the polymeric resistance heating element of the present invention can be seen. In the single wire embodiment of FIG. 6, the alignment groove 36 of the inner mold 300 is used to wrap the first wire pair having the helical lines 42 and 43. The preferred embodiment includes a refracted resistance wire, with the bend or helix end 44 being bent and wrapped around the pin 45. The pins 45 are ideally injection molded together with the internal molding part 300 as a part of the internal molding part 300.
Similarly, examples of double resistance wires are given. Here, a first pair of coiled wires 42 and 43 of the first resistance wire are suspended by a second coiled coil wire end 54 wound around the second pin 55 to the next successive pair of the same resistance wire. Separated from the perforations 46 and 47. The second pair of helical lines 52 and 53 of the second resistance wire are electrically connected to the second coil helical line end 54 and then the helical lines 46 and 47 in the next adjacent pair of alignment grooves. Is then wound around the inner molded part 300. Multi-coil assemblies have alternating pairs of helixes for each wire, as long as their conductive coils are insulated from each other by other insulating materials such as internal moldings or other plastic coatings, etc. It will be appreciated that the helix can be wound into a desired winding shape as a group of two or more helix lines of each resistance wire, or in an irregular number.
The polymer portion of the present invention preferably comprises a "heat resistant polymer" that does not significantly deform or melt at a fluid medium temperature of about 49-82 ° C (120-180 ° F). Most desirable are thermoplastic polymers having a melting temperature greater than 93 ° C. (200 ° F.), but certain ceramics and thermoset polymers are also useful for this purpose. The thermoplastic material preferably includes fluorocarbon, polyarylsulfone, polyimide, polyetheretherketone, polyphenylenesulfide, polyethersulfone, and mixtures and copolymers of these thermoplastic resins. Thermosetting polymers can also be used, but include certain epoxy resins, phenolic resins, and silicone resins. Liquid crystal polymers are also used to improve high temperature chemical processing.
In the preferred embodiment of the present invention, polyphenylene sulfide is most desirable because it can withstand high temperatures, is low cost, and has good workability, particularly during injection molding.
The polymer of the present invention can contain up to 5-40% by weight of fiber reinforcement such as graphite, glass, or polyamide fiber. These polymers can be mixed with various additives in order to improve thermal conductivity and mold releasability.
Thermal conductivity can also be improved by adding carbon, graphite, and metal powder or metal flakes. However, it should be noted that excess conductive material adversely affects the insulation and corrosion resistance effects of the preferred polymer coating. The polymer elements of the present invention are manufactured by combining these materials, or selected from these polymers, with or without additives for the various parts of the present invention that match the end use of the element. Can be used for
It is preferable that the resistance member used for supplying an electric current to the fluid heater of the present invention to generate heat contains a conductive and heat-resistant resistance metal. Certain copper, steel, and stainless steel alloys are suitable, but the most popular are nickel chromium alloys. Further, it is contemplated that a conductive polymer comprising graphite, carbon or metal powder, or fiber can be used, for example, as a substitute for a metal resistance member, as long as it generates sufficient resistance heating to heat a fluid such as water. It is done. The remaining conductors of the preferred polymer fluid heater 100 can be manufactured using these conductive members.
The standard rating of the preferred polymer fluid heater of the present invention used to heat water is 240V and 4500W, but the length of the conductive coil 14 and the wire diameter are varied and 1000W to 6000W, preferably 1700W to 4500W. Multiple ratings between. A low wattage of about 100-1200 W can be used to heat the gas. By using multiple coils or resistive members that terminate at different portions along the active element 10, double and triple watt capacities can be obtained.
From the foregoing, it will be appreciated that the present invention provides an improved fluid heating element for use in all types of fluid heating devices including water heaters and oil space heaters. The preferred device of the present invention is mostly a polymer, minimizing costs and substantially reducing chemical cell activity in the fluid storage tank. In one embodiment of the present invention, a polymer fluid heater is used with a polymer storage tank to avoid any corrosion associated with metal ions.
Alternatively, these polymer fluid heaters can be designed to be used separately as their storage containers that store and heat gases or fluids simultaneously. In such an embodiment, the through cavity 11 can be shaped in the shape of a tank or storage vessel, and the heating coil 14 can be disposed in the wall of the tank or storage vessel, and the fluid in the tank or storage vessel can be Or it is energized to heat the gas. The heating device of the present invention can also be used in food heaters, curler heaters, hair dryers, curler irons, clothes irons, and recreation heaters used in hot springs and pools.
The present invention is also applicable to through-heaters where the fluid medium passes through a polymer tube containing one or more of the windings or resistance members of the present invention. As the fluid medium passes through the inner diameter of such a tube, resistive heating occurs across the polymer wall at the inner diameter of the tube to heat the gas or liquid. Through-heaters are useful for hair dryers and often “on-demand” heaters used to heat water.
While various embodiments have been described, this is for the purpose of illustrating the invention and is not intended to limit the invention. Various modifications apparent to those skilled in the art are within the scope of the invention as set forth in the claims.
A heating element for heating a fluid, comprising a conductive resistance heating member (14) having a pair of free ends connected to a pair of terminals (12, 16), said resistance heating member heating Sealed and electrically insulated in a self-supporting polymer member (30) in contact with the fluid to be heated, and the resistance heating member allows the fluid to melt the polymer member through the polymer member. The heating element, which is sufficiently heated to a desired temperature.
The heating element of claim 1, wherein the polymeric member includes a core.
The heating element of claim 1, wherein the resistance heating member includes at least one helical coil.
The heating element of claim 1, wherein the polymeric member includes an injection molded core.
The heating element of claim 2, wherein the core includes at least one through hole for receiving and passing the fluid.
The heating element of claim 1, wherein the heating element is attached to a wall of the tank to heat the fluid in the tank.
The heating element of claim 2, wherein the polymer core is tubular in shape with parallel grooves thereon.
The heating element of claim 7, wherein the resistance heating member includes a helical coil disposed in the parallel groove.
The heating element of claim 1, wherein the polymeric member includes at least a portion of a sidewall of a fluid container.
The heating element of claim 1, wherein the heating element generates from about 1,000 watts to about 6,000 watts to heat the fluid to a temperature of at least about 49 ° C (120 ° F).
The heating element of claim 10, wherein the fluid is water.
The heating element of claim 1, wherein the heating element generates about 100 watts to about 1,200 watts of heat to heat the gaseous fluid.
The heating element is arranged through the wall of a tank used in connection with heating of a fluid such as air or water, and the polymer core has an inner tubular first having an end opening. An end, a cavity disposed adjacent to the end opening, and a flanged second end, wherein the resistance heating member is wrapped on the polymer core along the tubular first end The heating element of claim 2, wherein the heating element is a helical coil extending into the fluid and a polymer coating is disposed over the helical coil.
The heating element of claim 1, wherein the polymeric member has a thickness of about 0.04 inches to about 0.5 inches.
The heating of claim 1, wherein the thermoplastic polymer member comprises a resin selected from polyaryl-sulfone, polyimide, polyetheretherketone, polyphenylenesulfide, silicon, polyethersulfone, liquid crystal polymer, and mixtures and copolymers thereof. element.
The heating element of claim 1, wherein the polymer member contains an additive that improves the thermal conductivity of the polymer member.
The heating element of claim 1, wherein the polymer member contains about 5% to 40% of an additive based on the weight of the polymer to reinforce the polymer layer.
The heating element of claim 1, wherein the heating element comprises a tube having an open end and a closed end, the closed end having a threaded flange connector.
The heating element of claim 1, wherein the polymer member comprises polyphenylene sulfide or a liquid crystal polymer.
A water heater comprising the heating element of claim 1.
The heating element of claim 13, wherein the polymer coating and the polymer core comprise a common thermoplastic material having a melting point above a temperature of 93.3 ° C. (200 ° F.).
The heating element of claim 14, wherein a portion of the polymer coating is formed on the helical coil with a thickness of less than about 0.5 inches.
The heating element of claim 16, wherein the polymer coated portion is approximately 0.1 inches thick.
The heating element of claim 13, wherein the polymer core comprises glass, graphite, or polyamide fiber.
When a water heater including a tank for containing water and a heating element that is attached through a wall of the tank and that heats a part of the water in the tank by electric resistance, the heating element is energized A conductive resistance heating member capable of heating a portion of the water; and a polymer sealing material that contacts the resistance heating member and electrically contacts the water to electrically insulate the resistance heating member from the water. The polymer sealing material is self-supporting from the resistance heating member and efficiently transfers the heat generated by the resistance heating member to the water so that the temperature of the water is at least 49 ° C. (120 ° C. without melting). The water heater as set forth in F).
26. The water heater of claim 25, wherein the tank is made of a polymer.
26. The water heater of claim 25, wherein the heating element has an open end and a closed end, the closed end including a threaded flange connector.
28. The water heater of claim 27, wherein the threaded flange connector comprises a polymer.
26. The water heater of claim 25, wherein the polymeric material comprises an injection molded thermoplastic polymer.
26. The water heater of claim 25, wherein the polymeric material comprises polyphenylene sulfide.
According to a method of resistance heating of a fluid medium, (a) an electric resistance heating element including a conductive resistance heating member capable of heating the fluid medium when energized, and the resistance heating member are integrally enclosed; Providing a polymeric material that is self-supporting, thereby causing the resistive heating member to extend into the fluid medium and to be substantially surrounded by the fluid medium; and (b) providing the heating element to a tank wall And is immersed in the fluid medium so that the fluid medium is brought into direct contact with the polymer material while absorbing heat generated by the resistance heating member and transmitted through the polymer material. Said process characterized in that the polymeric material is maintained below its melting point.
32. The method of claim 31, wherein the polymeric material is formed by injection.
33. The method of claim 32, wherein the element has an open end that receives the fluid medium, the fluid medium absorbing heat from the polymeric material on both the inner and outer portions of the element.
JP52113996A 1994-12-29 1995-12-28 Polymer resistance heating element Expired - Fee Related JP3669635B2 (en)
PCT/US1995/016928 WO1996021336A1 (en) 1994-12-29 1995-12-28 Polymeric resistance heating element
JPH10512089A JPH10512089A (en) 1998-11-17
JP3669635B2 true JP3669635B2 (en) 2005-07-13
JP52113996A Expired - Fee Related JP3669635B2 (en) 1994-12-29 1995-12-28 Polymer resistance heating element
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