US4276466A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Heater with distributed heating element
Assignee: Littelfuse Inc
•
Filing: 1979-05-11
•
Granted: 1981-06-30
•
Expires: 1999-05-11
Abstract
Abstract A heater for heating liquids such as water in an aquarium comprises a water-impermeable housing including a heating section for immersion in the water. Within the heating section of the housing is a flexible, distributed planar heating element. The housing is resistant to breakage from mechanical and operating abuse and has a high heat transfer coefficient and high heat distortion temperature. To prevent the housing from melting when a control element of the heater malfunctions, preferably the aquarium heater includes temperature limiting means such as a circuit protection element comprising a material having a positive temperature coefficient of resistance. Preferably, the heating section of the housing is fabricated with large surface area walls to accommodate the planar heating element, and is provided with coupling means for maintaining the heating element thermally coupled to the walls of the heating section. The coupling means can be a ribbed support for holding the heating element against the heating section walls.
Inventors
- 👤 Lee M. Middleman
- 👤 Roger S. Goodrich
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 14:07
CPC Classifications
A; A01; A01K; A01K63/00; A01K63/06; A01K63/065; H; H05; H05B; H05B3/00; H05B3/78; H05B3/80
Claims Analysis
Total Claims: 54
Claim 1
Independent Claim
69 words
An article for heating a liquid comprising: (a) a water-impermeable housing fabricated from a meltable material having a notched Izod impact strength of at least about 0.5 ft-lbs/in. and (b) a flexible heating element within the housing and in intimate engagement with the housing, the flexible heating element being capable of providing from about 1 to about 10 watts per square inch of surface area of the heating element.
Claim 2
Dependent Claim
69 words
An article for heating a liquid comprising: (a) a water-impermeable housing fabricated from a meltable material having a notched Izod impact strength of at least about 0.5 ft-lbs/in. and (b) a flexible heating element within the housing and in intimate engagement with the housing, the flexible heating element being capable of providing from about 1 to about 10 watts per square inch of surface area of the heating element.
Claim 3
Dependent Claim
29 words
The article of claim 1 in which the housing is composed of a material having a heat transfer coefficient of at least about 2 BTU-inches per hour-square foot-° F.
Claim 4
Dependent Claim
28 words
The article of claim 1 in which the housing is composed of a material having a heat distortion temperature at 264 psi of at least about 350° F.
Claim 5
Dependent Claim
31 words
The article of claim 1 including temperatue limiting means capable of preventing the heating element from raising the temperature of the housing to a temperature at which it softens or melts.
Claim 6
Dependent Claim
30 words
The article of claim 4 in which the temperature limiting means is a circuit protection element comprising at least two electrodes and a PTC element composed of a PTC composition.
Claim 7
Dependent Claim
21 words
The article of claim 4 in which the heating element comprises a PTC composition that serves as the temperature limiting means.
Claim 8
Dependent Claim
22 words
The article of claim 1 including a temperature control device for regulating the heating element for controlling the temperature of the liquid.
Claim 9
Dependent Claim
46 words
The article of claim 1 in which the heating element comprises an electrically conductive film sandwiched between two sheets of electrically insulating material, the electrically conductive film consisting of a conductive material dispersed throughout a non-conductive colloidal silica binder, with spaced electrodes applied to the film.
Claim 10
Dependent Claim
12 words
The article of claim 8 in which the conductive material comprises graphite.
Claim 11
Dependent Claim
19 words
The article of claim 8 or 9 in which at least one sheet of electrically insulating material comprises asbestos.
Claim 12
Dependent Claim
21 words
The article of claim 1 in which the heating element is sufficiently flexible to conform to the shape of the housing.
Claim 13
Dependent Claim
25 words
The article of claim 1 in which the heating element is capable of providing at least about 3 watts per square inch of surface area.
Claim 14
Dependent Claim
26 words
The article of claim 1 in which the heating element is capable of providing no more than about 7 watts per square inch of surface area.
Claim 15
Dependent Claim
71 words
An article for heating a liquid comprising: (a) a water-impermeable housing; (b) within the housing, a heating element sufficiently flexible to conform to the shape of the housing and capable of providing from about 1 to about 10 watts per square inch of surface area of the heating element; and (c) coupling means for maintaining the heating element thermally coupled to and in intimate engagement with the interior of the housing.
Claim 16
Dependent Claim
71 words
An article for heating a liquid comprising: (a) a water-impermeable housing; (b) within the housing, a heating element sufficiently flexible to conform to the shape of the housing and capable of providing from about 1 to about 10 watts per square inch of surface area of the heating element; and (c) coupling means for maintaining the heating element thermally coupled to and in intimate engagement with the interior of the housing.
Claim 17
Dependent Claim
28 words
The article of claim 14 in which the coupling means comprises a support member that maintains the heating element in intimate engagement with the interior of the housing.
Claim 18
Dependent Claim
26 words
The article of claim 14 in which the housing is composed of a material having a notched Izod impact strength of at least about 0.5 ft-lbs/in.
Claim 19
Dependent Claim
31 words
The article of claim 14 or 16 in which the housing is composed of a material having a heat transfer coefficient of at least about 2 BTU-inches per hour-square foot-° F.
Claim 20
Dependent Claim
28 words
The article of claim 14 in which the housing is composed of a material having a heat distortion temperature at 264 psi of at least about 350° F.
Claim 21
Dependent Claim
149 words
A heater capable of being immersed in liquids such as water comprising: (a) a water-impermeable, electrically insulating closed housing comprising a hollow heating section for immersion in water, walls of the heating section having a a notched Izod impact strength of at least about 0.5 ft-lbs/inc. and a heat distortion temperature at 264 psi of at least about 350° F.; (b) a distributed heating element within the heating section of the housing, the heating element being capable of providing from about 1 to about 10 watts per square inch of surface area and being sufficiently flexible to conform to the interior surface of the heating section; (c) coupling means for maintaining the heating element thermally coupled with the internal surface of the heating section walls; and (d) temperature limiting means for preventing the heating element from heating the housing to a temperature at which the housing melts or softens.
Claim 22
Dependent Claim
149 words
A heater capable of being immersed in liquids such as water comprising: (a) a water-impermeable, electrically insulating closed housing comprising a hollow heating section for immersion in water, walls of the heating section having a a notched Izod impact strength of at least about 0.5 ft-lbs/inc. and a heat distortion temperature at 264 psi of at least about 350° F.; (b) a distributed heating element within the heating section of the housing, the heating element being capable of providing from about 1 to about 10 watts per square inch of surface area and being sufficiently flexible to conform to the interior surface of the heating section; (c) coupling means for maintaining the heating element thermally coupled with the internal surface of the heating section walls; and (d) temperature limiting means for preventing the heating element from heating the housing to a temperature at which the housing melts or softens.
Claim 23
Dependent Claim
27 words
The heater of claim 19 in which walls of the heating section have a heat transfer coefficient of at least about 2 BTU-inches per hour-square foot-° F.
Claim 24
Dependent Claim
30 words
The heater of claim 19 in which the temperature limiting means is a circuit protection element comprising at least two electrodes and a PTC element composed of a PTC composition.
Claim 25
Dependent Claim
21 words
The heater of claim 19 in which the heating element comprises a PTC composition that serves as the temperature limiting means.
Claim 26
Dependent Claim
26 words
The heater of claim 19 in which the coupling means comprises a support member that maintains the heating element in intimate engagement with heating section walls.
Claim 27
Dependent Claim
179 words
An aquarium heater comprising: (a) a water-impermeable, electrically insulating closed housing comprising a hollow, thin, elongated, wedge-shaped heating section for immersion in water in an aquarium, the heating section walls having a heat transfer coefficient of at least about 2 BTU-inches per hour-square foot-° F., a notched Izod impact strength of at least about 0.5 ft-lbs/in., and a heat distortion temperature at 264 psi of at least about 350° F.; (b) a flexible, distributed heating element within the heating section of the housing, the heating element being capable of providing from about 3 to about 7 watts per square inch of surface area; (c) a wedge-shaped support for maintaining the heating element in intimate engagement with the internal surface of both of the wider side walls; and (d) a circuit protection element comprising at least two electrodes and a PTC element composed of a PTC composition, the temperature limiting device being selectively located in the heating section of the housing for preventing the heating element from heating the housing to a temperature at which the housing melts or softens.
Claim 28
Dependent Claim
179 words
An aquarium heater comprising: (a) a water-impermeable, electrically insulating closed housing comprising a hollow, thin, elongated, wedge-shaped heating section for immersion in water in an aquarium, the heating section walls having a heat transfer coefficient of at least about 2 BTU-inches per hour-square foot-° F., a notched Izod impact strength of at least about 0.5 ft-lbs/in., and a heat distortion temperature at 264 psi of at least about 350° F.; (b) a flexible, distributed heating element within the heating section of the housing, the heating element being capable of providing from about 3 to about 7 watts per square inch of surface area; (c) a wedge-shaped support for maintaining the heating element in intimate engagement with the internal surface of both of the wider side walls; and (d) a circuit protection element comprising at least two electrodes and a PTC element composed of a PTC composition, the temperature limiting device being selectively located in the heating section of the housing for preventing the heating element from heating the housing to a temperature at which the housing melts or softens.
Claim 29
Dependent Claim
22 words
The aquarium heater of claim 24 in which the walls of the heating section are from about 0.05 to 0.2 inch thick.
Claim 30
Dependent Claim
15 words
The aquarium heater of claim 24 in which the housing is composed of polyphenylene sulfide.
Claim 31
Dependent Claim
24 words
The aquarium heater of claim 24 in which the heating element is capable of providing about 5 watts per square inch of surface area.
Claim 32
Dependent Claim
47 words
The aquarium heater of claim 24 in which the heating element comprises an electrically conductive film sandwiched between two sheets of electrically insulating material, the electrically conductive film consisting of a conductive material dispersed throughout a non-conductive colloidal silica binder, with spaced electrodes applied to the film.
Claim 33
Dependent Claim
25 words
The aquarium heater of claim 24 in which the wedge-shaped support comprises a body member having a plurality of projections that support the heating element.
Claim 34
Dependent Claim
31 words
The aquarium heater of claim 29 in which the projections are parallel, spaced apart ribs, the ribs being substantially parallel to the longitudinal axis of the heating section of the housing.
Claim 35
Dependent Claim
20 words
The aquarium heater of claim 29 or 30 including a gap in the projections for mounting of the PTC element.
Claim 36
Dependent Claim
29 words
The aquarium heater of claim 24 in which the heating section comprising four substantially planar side walls, two opposing side walls being substantially wider than the other side walls.
Claim 37
Dependent Claim
15 words
The aquarium heater of claim 24 in which the heating section is oval in cross-section.
Claim 38
Dependent Claim
81 words
An aquarium heater comprising a closed housing and a planar distributed heating element within the housing, the housing including (i) means for mounting the heater on a side wall of the aquarium and (ii) a hollow, thin, elongated heating section for immersion in water in the aquarium, the heating section comprising two opposed side walls wider than the other side walls of the heating section, the heater including means fo supporting the heating element against both of the wider side walls.
Claim 39
Dependent Claim
81 words
An aquarium heater comprising a closed housing and a planar distributed heating element within the housing, the housing including (i) means for mounting the heater on a side wall of the aquarium and (ii) a hollow, thin, elongated heating section for immersion in water in the aquarium, the heating section comprising two opposed side walls wider than the other side walls of the heating section, the heater including means fo supporting the heating element against both of the wider side walls.
Claim 40
Dependent Claim
44 words
The aquarium heater of claim 34 in which the support means is a wedge-shaped support conforming to the shape of the heating section of the housing, wherein the wedge-shaped support comprises a body member having a plurality of projections which support the heating element.
Claim 41
Dependent Claim
31 words
The aquarium heater of claim 35 in which the projections are parallel, spaced apart ribs, the ribs being substantially parallel to the longitudinal axis of the heating section of the housing.
Claim 42
Dependent Claim
44 words
The aquarium heater of claim 34 or 36 including a circuit protection element comprising at least two electrodes and a PTC element composed of a PTC composition capable of preventing the heating element from the housing to a temperature at which the housing melts.
Claim 43
Dependent Claim
18 words
The aquarium heater of claim 37 including a gap in the projections for mounting of the PTC element.
Claim 44
Dependent Claim
98 words
An article for heating in a liquid comprising: (a) a water-impermeable housing fabricated from a meltable material having a notched Izod impact strength of at least about 0.5 ft-lbs/in., (b) within the housing, a flexible heating element capable of providing from about 1 to about 10 watts per square inch of surface area of the heating element, and (c) a circuit protection element comprising at least two electrodes and a PTC element composed of a PTC composition for preventing the heating element from raising the temperature of the housing to a temperature at which it softens or melts.
Claim 45
Dependent Claim
98 words
An article for heating in a liquid comprising: (a) a water-impermeable housing fabricated from a meltable material having a notched Izod impact strength of at least about 0.5 ft-lbs/in., (b) within the housing, a flexible heating element capable of providing from about 1 to about 10 watts per square inch of surface area of the heating element, and (c) a circuit protection element comprising at least two electrodes and a PTC element composed of a PTC composition for preventing the heating element from raising the temperature of the housing to a temperature at which it softens or melts.
Claim 46
Dependent Claim
28 words
The article of claim 39 in which the housing is composed of a material having a heat transfer coefficient of at least about 2 BTU-inches per hour-square foot-°F.
Claim 47
Dependent Claim
28 words
The article of claim 39 in which the housing is composed of a material having a heat distortion temperature at 264 psi of at least about 350° F.
Claim 48
Dependent Claim
26 words
The article of claim 12 in which the heating element is capable of providing no more than about 7 watts per square inch of surface area.
Claim 49
Dependent Claim
151 words
An article for heating a liquid comprising: (a) a water-impermeable, electrically insulating housing comprising a hollow heating section for immersion in the liquid, the walls of the heating section being from 0.05 to 0.2 inches thick and being composed of a material having a notched Izod impact strength of at least 0.5 ft-lbs/in., a heat distortion temperature at 264 psi of at least 350° F., and a thermal conductivity of at least 2 BTU-inches per hour-square foot-° F.; (b) a flexible distributed heating element within the heating section of the housing, the heating element being capable of providing from about 1 to about 10 watts per square inch of surface area and conforming to the interior surface of the heating section; (c) a support member for maintaining the heating element in contact with the internal surface of the heating section walls; and (d) an adjustable thermostat for regulating the heating element.
Claim 50
Dependent Claim
151 words
An article for heating a liquid comprising: (a) a water-impermeable, electrically insulating housing comprising a hollow heating section for immersion in the liquid, the walls of the heating section being from 0.05 to 0.2 inches thick and being composed of a material having a notched Izod impact strength of at least 0.5 ft-lbs/in., a heat distortion temperature at 264 psi of at least 350° F., and a thermal conductivity of at least 2 BTU-inches per hour-square foot-° F.; (b) a flexible distributed heating element within the heating section of the housing, the heating element being capable of providing from about 1 to about 10 watts per square inch of surface area and conforming to the interior surface of the heating section; (c) a support member for maintaining the heating element in contact with the internal surface of the heating section walls; and (d) an adjustable thermostat for regulating the heating element.
Claim 51
Dependent Claim
51 words
The article in accordance with claim 43 which further comprises a circuit protection device which comprises a PTC element composed of a PTC composition, and which in the event of failure of said adjustable thermostat, prevents the heating element from heating the housing to a temperature above the material's melting point.
Claim 52
Dependent Claim
19 words
The article in accordance with claim 43 wherein the heating element is a self-limiting heater comprising a PTC composition.
Claim 53
Dependent Claim
77 words
The article in accordance with claim 44 wherein the support member is a rigid support core comprising a body member and a plurality of parallel, spaced-apart ribs projecting from said body member, the ribs being substantially parallel to the longitudinal axis of the heating section of the housing and maintaining the heating element in contact with the internal surface of the heating section walls, and said circuit protection device is mounted in a gap between said ribs.
Claim 54
Dependent Claim
31 words
The article in accordance with claim 43 in which the heating element is capable of providing at least 3 but no more than 7 watts per square inch of surface area.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-06-29 | 1984-12-29 | 1985-06-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-06-29 | 1988-12-29 | 1989-06-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-06-29 | 1992-12-29 | 1993-06-30 | $7700.00 | Window Closed / Lapsed |