US3474372A - Temperature-responsive switch having self-contained heater - Google Patents

Temperature-responsive switch having self-contained heater Download PDF

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Publication number
US3474372A
US3474372A US616586A US3474372DA US3474372A US 3474372 A US3474372 A US 3474372A US 616586 A US616586 A US 616586A US 3474372D A US3474372D A US 3474372DA US 3474372 A US3474372 A US 3474372A
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United States
Prior art keywords
switch
temperature
heater
conductor
responsive switch
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Expired - Lifetime
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US616586A
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English (en)
Inventor
William R Davenport
Elmer T Davenport
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CROWELL DESIGNS Inc
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CROWELL DESIGNS Inc
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H35/00—Switches operated by change of a physical condition
    • H01H35/18—Switches operated by change of liquid level or of liquid density, e.g. float switch
    • H01H35/183—Switches operated by change of liquid level or of liquid density, e.g. float switch making use of a thermal switch

Definitions

  • 337-1 2 Claims ABSTRACT OF THE DISCLOSURE
  • a temperature-responsive switch closed-when-cool, open-when-warm, is surrounded by a constantly energized electrical heater winding. The switch remains open when not contacted by the liuid, eg., water, to be detected.
  • Electrical apparatus e.g., a bilge pump, is connected to a source of power via the switch. When iluid contacts the switch, the latter is cooled and closes, and apparatus is energized.
  • This invention relates to a device for detecting the presence of a particular fluid at a certain point in an enclosure, and controlling the operation of an electrical apparatus in response to such detection.
  • the invention comprises, in brief, a temperature-responsive switch built so that its contacts are closed when cool and open when warm.
  • the switch is connected in a circuit between a power source and an apparatus to be controlled.
  • a constantly energized electric heater surrounds the switch and elevates its temperature sufficiently to maintain the contacts separated, and hence the apparatus deenergized.
  • the switch closes and the apparatus begins operating.
  • the switch and heater are preferably encapsulated in glass or a plastic so that the fluid being detected can have no deleterious effect on these components.
  • the heater preferably includes high and low heat portions, the high heat portion being energized only during the periods of operation of the apparatus, to rapidly raise the temperature of the switch, and cause it to open should no fluid be detected by the switch.
  • FIG. 1 is a fluid detection device according to this invention.
  • FIG. 2 is a schematic circuit diagram indicating how the device may be employed.
  • the present invention may include any suitable type of temperature-responsive switch.
  • a switch of the type made by Metals & Control Inc., a subsidiary of Texas Instruments Incorporated, and Sold under the trademark Klixon may be employed. These switches are referred to as Miniature Snap-Acting Protectors 9700 Series.
  • such a switch includes a stationary contact and a movable contact 11.
  • the stationary contact 10 is a silver strip mounted on a metal support 12, which itself is mounted or an insulator 3,474,372 Patented Oct. 21, 1969 block 13.
  • the movable contact 11 is a silver button secured to a snap-acting disk 14.
  • Such a disk is wellknown and has a circular or oval shape when viewed face-on, and is dished.
  • the switch is cool, the upper face of disl. 14 is convex and the lower face is concave.
  • it does not gradually change shape, as is true of an ordinary bi-metallic strip.
  • the end of the disk 14 opposite the contact button 11 is sandwiched between the arms of a U-shaped bend in a metal terminal 15.
  • the terminal 15 and contact 10 are separated by a ceramic insulator 18, and the entire assembly is enclosed within a metal housing 19.
  • a conductor 20 engages the contact 10, and a conductor 21 engages the terminal 15, these conductors extending out of the open end of the housing 19, and being covered by insulation 22.
  • the conductors are separated by an insulation member 24.
  • an electric heater 23 is provided, in the form of a high resistance wire wound around the housing 19, One end of the winding 23 is connected t0 the conductor 20, and the other end is connected to the conductor 21.
  • the winding 23 is tapped at some point along its length, and conductor 26 is connected to the winding at the tapped point, the conductor having insulation 27.
  • a suitable material 28 such as an epoxy resin, or glass. The material 28 covers part of the insulation 22 and 27, so that only the insulation covered conductors extend from the encapsulation.
  • FIG. 2 shows the switch connected in a circuit for controlling the motor 25 of a bilge pump. Power for running the motor is supplied by a battery 29, one terminal of which is connected to ground via a conductor 30. The other terminal of the battery is connected to a manually operable selector switch 31. If the switch is moved into engagement with the contact 34, a circuit will be completed from the battery, 4through switch 31, and conductor 20, and motor 25, for manually controlling the operation of the motor. On the other hand, if the switch is swung into engagement with contact 35, the circuit will be set for automatic operation of the pump motor 25.
  • the 4broken line in FIG. 2 represents the encapsulation material 28, and the encapsulated detection device is mounted in the bilge, possibly on the pump housing, at an appropriate location to be covered with water when a significant amount of water accumulates in the bilge.
  • a circuit is completed from the battery 29, through conductor 21, temperature-responsive switch 10, 11, conductor 20, and motor 25, to initially actuate the pump, regardless of whether or not there is water in the bilge.
  • a circuit is also completed from the battery, through switch 31, conductor 21-, the low heat portion 36 of heater 23, and conductor 26.
  • a circuit is completed from the battery, through switch 31, conductor 21, switch 10, 11, high heat portion 37 of heater 23, and conductor 26.
  • the connection of con- 3 ductor 26 to the winding 23 is such that the portion 36 is longer than the portion 37, and hence has more resistance and produces less heat.
  • the temperature-responsive switch heats up quickly, and the contacts and 11 separate. Consequently, the motor 25 stops running, and the heater portion 37 is deenergized.
  • the heat developed by the heater portion 36 is capable of maintaining the temperature of the switch high enough to keep the contacts 10 and 11 separated.
  • the pump remains inactive.
  • the temperature of the device drops because the water conducts heat from the device faster than does the air which otherwise surrounds it. As a result, the contacts 10 and 11 close, and the pump motor 25 runs.
  • the winding 23 quickly heats up the switch, and the contacts 10 and 11 open.
  • the portion 36 of the winding was 6.85 feet long and had a resistance of 72 ohms, and the portion 37 was 2.28 feet long and had a resistance of 24 ohms.
  • the portion 36 developed 2 watts, and the portion 37, 6 watts.
  • the specific arrangement delined above may be varied to suit the particular circumstances of the environment in which the device is used.
  • the point at which the winding 23 is tapped for the connection of conductor 26 may be varied, and if desired, two separate windings may be used to form the high and low heat portions, 37 and 36, ofthe heater 23.
  • a device for detecting the presence of a particular uid at a certain point within an enclosure and controlling the operation of an electrical apparatus in response torsuch detection comprising a temperature-responsive switch between a source of power and the apparatus, said switch being closed when relatively cool and open ⁇ when relatively warm, electrical heating means adjacent to said switch and connected in parallel with it, said heating means serving to elevate the temperature of said switch to keep it open when it is out of contact with the fluid, whereupon the apparatus is deenergized, said switch becoming relatively cool and closing when contacted by said fluid, whereupon the apparatus is connected to the power source, and a heat-conductive housing enclosing said switch, said heating means comprising a resistance wire wound around said housing and including a relatively high resistance-low heat section, and

Landscapes

  • Control Of Resistance Heating (AREA)
  • Resistance Heating (AREA)
  • Thermally Actuated Switches (AREA)
US616586A 1967-02-16 1967-02-16 Temperature-responsive switch having self-contained heater Expired - Lifetime US3474372A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US61658667A 1967-02-16 1967-02-16

Publications (1)

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US3474372A true US3474372A (en) 1969-10-21

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US616586A Expired - Lifetime US3474372A (en) 1967-02-16 1967-02-16 Temperature-responsive switch having self-contained heater

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US (1) US3474372A (de)
DE (1) DE1623957A1 (de)
GB (1) GB1178910A (de)

Cited By (24)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3786463A (en) * 1972-03-20 1974-01-15 Gte Sylvania Inc Fluid level sensor
US3878538A (en) * 1974-04-03 1975-04-15 Gte Sylvania Inc Position sensor with thermal time delay
US3962665A (en) * 1975-02-13 1976-06-08 Ideal Corporation Thermally actuated liquid level sensor
US4086558A (en) * 1976-02-09 1978-04-25 Texas Instruments Incorporated Motor protector and system
US4224591A (en) * 1978-12-04 1980-09-23 Texas Instruments Incorporated Motor protector with metal housing and with preformed external heater thereon
US4318687A (en) * 1977-12-28 1982-03-09 Inoue-Japax Research Incorporated Gas burner control system
US4334209A (en) * 1979-05-04 1982-06-08 Gte Products Corporation Glass enclosed three lead circuit breaker
EP0104809A1 (de) * 1982-09-27 1984-04-04 Texas Instruments Incorporated Motorschutzvorrichtung
US4486732A (en) * 1982-08-26 1984-12-04 Wells Robert M Ambient compensated motor protector
US4837655A (en) * 1983-07-18 1989-06-06 Gte Products Corporation Overtemperature protector for incandescent lamp
US5049849A (en) * 1990-08-30 1991-09-17 Texas Instruments Incorporated Circuit breaker
US5200872A (en) * 1989-12-08 1993-04-06 Texas Instruments Incorporated Internal protection circuit for electrically driven device
US5303461A (en) * 1993-01-27 1994-04-19 Sundstrand Corporation Thermal protection for electrical machines
US5729416A (en) * 1995-05-30 1998-03-17 General Electric Company Motor starter and protector module
US5844465A (en) * 1995-12-18 1998-12-01 Texas Instruments Incorporated Temperature compensated time-delay switch
US6018286A (en) * 1998-11-20 2000-01-25 Therm-O-Disc, Incorporated Thermal switch
US6069551A (en) * 1997-05-02 2000-05-30 Therm-O-Disc, Incorporated Thermal switch assembly
US6140903A (en) * 1997-11-24 2000-10-31 Therm-O-Disc, Incorporated Thermal switch
US6191679B1 (en) 1997-05-02 2001-02-20 Thermo-O-Disc, Incorporated Thermal switch assembly
US6239686B1 (en) 1999-08-06 2001-05-29 Therm-O-Disc, Incorporated Temperature responsive switch with shape memory actuator
US6342826B1 (en) 1999-08-11 2002-01-29 Therm-O-Disc, Incorporated Pressure and temperature responsive switch assembly
US20060232905A1 (en) * 2005-04-19 2006-10-19 Bradfield Michael D Electrical thermal overstress protection device
US20060273876A1 (en) * 2005-06-02 2006-12-07 Pachla Timothy E Over-temperature protection devices, applications and circuits
US20150279596A1 (en) * 2014-03-27 2015-10-01 Tyco Electronics Japan G.K. Insulated Thermal Cut-Off Device

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2831198C2 (de) * 1978-07-15 1982-11-04 Limitor AG, 8022 Zürich Bimetalltemperaturschalter

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2248531A (en) * 1939-03-03 1941-07-08 Richard J Fitz Maurice Thermostat
US2354529A (en) * 1942-06-03 1944-07-25 Edison Inc Thomas A Control device
US2403803A (en) * 1944-09-21 1946-07-09 Gen Electric Electric blanket
US2463891A (en) * 1944-11-30 1949-03-08 Stewart Warner Corp Electric switch
US3213246A (en) * 1962-04-09 1965-10-19 Texas Instruments Inc Protective encapsulation for electrical devices
US3335243A (en) * 1965-01-26 1967-08-08 Gen Motors Corp Bimetal indicator device with a heater energized under all operative conditions

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2248531A (en) * 1939-03-03 1941-07-08 Richard J Fitz Maurice Thermostat
US2354529A (en) * 1942-06-03 1944-07-25 Edison Inc Thomas A Control device
US2403803A (en) * 1944-09-21 1946-07-09 Gen Electric Electric blanket
US2463891A (en) * 1944-11-30 1949-03-08 Stewart Warner Corp Electric switch
US3213246A (en) * 1962-04-09 1965-10-19 Texas Instruments Inc Protective encapsulation for electrical devices
US3335243A (en) * 1965-01-26 1967-08-08 Gen Motors Corp Bimetal indicator device with a heater energized under all operative conditions

Cited By (30)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3786463A (en) * 1972-03-20 1974-01-15 Gte Sylvania Inc Fluid level sensor
US3878538A (en) * 1974-04-03 1975-04-15 Gte Sylvania Inc Position sensor with thermal time delay
US3962665A (en) * 1975-02-13 1976-06-08 Ideal Corporation Thermally actuated liquid level sensor
US4086558A (en) * 1976-02-09 1978-04-25 Texas Instruments Incorporated Motor protector and system
US4318687A (en) * 1977-12-28 1982-03-09 Inoue-Japax Research Incorporated Gas burner control system
US4224591A (en) * 1978-12-04 1980-09-23 Texas Instruments Incorporated Motor protector with metal housing and with preformed external heater thereon
US4334209A (en) * 1979-05-04 1982-06-08 Gte Products Corporation Glass enclosed three lead circuit breaker
US4486732A (en) * 1982-08-26 1984-12-04 Wells Robert M Ambient compensated motor protector
EP0104809A1 (de) * 1982-09-27 1984-04-04 Texas Instruments Incorporated Motorschutzvorrichtung
US4837655A (en) * 1983-07-18 1989-06-06 Gte Products Corporation Overtemperature protector for incandescent lamp
US5200872A (en) * 1989-12-08 1993-04-06 Texas Instruments Incorporated Internal protection circuit for electrically driven device
US5049849A (en) * 1990-08-30 1991-09-17 Texas Instruments Incorporated Circuit breaker
US5303461A (en) * 1993-01-27 1994-04-19 Sundstrand Corporation Thermal protection for electrical machines
WO1994017540A1 (en) * 1993-01-27 1994-08-04 Sundstrand Corporation Thermal protection for electrical machines
US5729416A (en) * 1995-05-30 1998-03-17 General Electric Company Motor starter and protector module
US5844465A (en) * 1995-12-18 1998-12-01 Texas Instruments Incorporated Temperature compensated time-delay switch
US6069551A (en) * 1997-05-02 2000-05-30 Therm-O-Disc, Incorporated Thermal switch assembly
US6191679B1 (en) 1997-05-02 2001-02-20 Thermo-O-Disc, Incorporated Thermal switch assembly
US6294977B1 (en) 1997-05-02 2001-09-25 Therm-O-Disc, Incorporated Thermal switch assembly
US6300858B1 (en) * 1997-11-24 2001-10-09 Thermo-O-Disc, Incorporated Thermal switch
US6140903A (en) * 1997-11-24 2000-10-31 Therm-O-Disc, Incorporated Thermal switch
US6018286A (en) * 1998-11-20 2000-01-25 Therm-O-Disc, Incorporated Thermal switch
US6078244A (en) * 1998-11-20 2000-06-20 Therm-O-Disc, Incorporated Thermal switch
US6239686B1 (en) 1999-08-06 2001-05-29 Therm-O-Disc, Incorporated Temperature responsive switch with shape memory actuator
US6342826B1 (en) 1999-08-11 2002-01-29 Therm-O-Disc, Incorporated Pressure and temperature responsive switch assembly
US20060232905A1 (en) * 2005-04-19 2006-10-19 Bradfield Michael D Electrical thermal overstress protection device
US7209337B2 (en) 2005-04-19 2007-04-24 Remy International, Inc. Electrical thermal overstress protection device
US20060273876A1 (en) * 2005-06-02 2006-12-07 Pachla Timothy E Over-temperature protection devices, applications and circuits
US20150279596A1 (en) * 2014-03-27 2015-10-01 Tyco Electronics Japan G.K. Insulated Thermal Cut-Off Device
US9831054B2 (en) * 2014-03-27 2017-11-28 Littelfuse, Inc. Insulated thermal cut-off device

Also Published As

Publication number Publication date
GB1178910A (en) 1970-01-21
DE1623957A1 (de) 1971-07-22

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