US4956544A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Overheat protected electric cartridge heater
Assignee: Hotwatt Inc
•
Filing: 1988-07-26
•
Granted: 1990-09-11
•
Expires: 2008-07-26
Abstract
Abstract An electric cartridge heater for use as an immersion heater in a steam table tank has a tubular elongate stainless steel sheath with a curved inner surface attached to a riser tube adapted to be connected to a wall of the tank and contains an electric heater element. A copper heat transfer member having an enlarged, curved surface complementary to the inner surface of the sheath is urged into close, intimate thermal contact therewith and transfers heat from the sheath to a bimetal thermostat for turning off the heater element in response to a rise in temperature of the sheath above a predetermined level.
Inventors
- 👤 Samuel S. Sayward, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 13:44
CPC Classifications
H; H05; H05B; H05B1/00; H05B1/02; H05B1/0202; H05B1/0213; F; F22; F22B; F22B1/00; F22B1/28; F22B1/284; H01; H01H; H01H37/00; H01H37/02; H01H37/32; H01H37/34; H05B3/00; H05B3/78; H05B3/82
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
157 words
A cartridge heater having an overheat protection device, for use in a steam table tank, the heater comprising: a riser tube attached to the inside of the tank; a tubular elongate sheath having a curved inner surface attached to said riser tube; an electric heater element inside said sheath; a heat transfer member having an enlarged, curved surface complementary to the curved inner surface of said sheath for engaging the inner surface of said sheath in an area of said sheath remote from said heater element; means urging said heat transfer member into close, intimate, thermal contact with the inner surface of said sheath; and switch means for turning the heater element on and off, said switch means including a thermally sensitive element responsive to a rise in the temperature of said heat transfer member above a predetermined level for actuating said switch means to interrupt current flow to the heater element to prevent it from overheating.
Claim 2
Dependent Claim
157 words
A cartridge heater having an overheat protection device, for use in a steam table tank, the heater comprising: a riser tube attached to the inside of the tank; a tubular elongate sheath having a curved inner surface attached to said riser tube; an electric heater element inside said sheath; a heat transfer member having an enlarged, curved surface complementary to the curved inner surface of said sheath for engaging the inner surface of said sheath in an area of said sheath remote from said heater element; means urging said heat transfer member into close, intimate, thermal contact with the inner surface of said sheath; and switch means for turning the heater element on and off, said switch means including a thermally sensitive element responsive to a rise in the temperature of said heat transfer member above a predetermined level for actuating said switch means to interrupt current flow to the heater element to prevent it from overheating.
Claim 3
Dependent Claim
31 words
The cartridge heater of claim 1 in which said heat transfer member engages said sheath in an area that proximates the temperature of said heater element to prevent it from overheating.
Claim 4
Dependent Claim
25 words
The cartridge heater of claim 1 in which the heater element includes two separate, spaced-apart sections and said heat transfer member is between said sections.
Claim 5
Dependent Claim
27 words
The cartridge heater of claim 1 in which said heater transfer member is shaped to closely conform to the shape of said inner surface of the sheath.
Claim 6
Dependent Claim
14 words
The cartridge heater of claim 1 in which said heat transfer member is copper.
Claim 7
Dependent Claim
13 words
The cartridge heater of claim 1 in which said sheath is stainless steel.
Claim 8
Dependent Claim
16 words
The cartridge heater of claim 1 in which said thermally sensitive element includes a bimetal thermostat.
Claim 9
Dependent Claim
124 words
A cartridge heater for a steam table tank, comprising: a riser tube attached to the inside of the tank; a tubular elongate sheath having a curved inner surface attached to said riser tube; an electrical heater element inside said sheath, a thermally sensitive switch for controlling current flow to said heater element in response to a rise in temperature of said sheath above a predetermined level to interrupt current flow to said heater element to prevent it from overheating; a heat transfer member having an enlarged curved surface for engaging the inner surface of said sheath for transferring heat from said sheath to said switch; and means urging said heat transfer member into close, intimate thermal contact with the inner surface of said sheath.
Claim 10
Dependent Claim
124 words
A cartridge heater for a steam table tank, comprising: a riser tube attached to the inside of the tank; a tubular elongate sheath having a curved inner surface attached to said riser tube; an electrical heater element inside said sheath, a thermally sensitive switch for controlling current flow to said heater element in response to a rise in temperature of said sheath above a predetermined level to interrupt current flow to said heater element to prevent it from overheating; a heat transfer member having an enlarged curved surface for engaging the inner surface of said sheath for transferring heat from said sheath to said switch; and means urging said heat transfer member into close, intimate thermal contact with the inner surface of said sheath.
Claim 11
Dependent Claim
24 words
The of claim 8 in which said switch includes electrical terminals connected by electrical leads to an external switch for disabling said heater element.
Claim 12
Dependent Claim
25 words
The of claim 8 in which said heat transfer member is in thermal contact with said sheath in an area remote from said heater element.
Claim 13
Dependent Claim
13 words
The of claim 8 in which said cartridge heater contains two heater elements.
Claim 14
Dependent Claim
20 words
The of claim 11 in which said switch is positioned between heater elements in an area remote from heater elements.
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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) | 1993-09-10 | 1994-03-12 | 1994-09-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-09-10 | 1998-03-12 | 1998-09-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-09-10 | 2002-03-12 | 2002-09-11 | $7700.00 | Window Closed / Lapsed |