US3396265A - Electrically heated bedcover overtemperature control - Google Patents

Electrically heated bedcover overtemperature control Download PDF

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Publication number
US3396265A
US3396265A US517570A US51757065A US3396265A US 3396265 A US3396265 A US 3396265A US 517570 A US517570 A US 517570A US 51757065 A US51757065 A US 51757065A US 3396265 A US3396265 A US 3396265A
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US
United States
Prior art keywords
bedcover
control
contacts
blade
blades
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US517570A
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English (en)
Inventor
Chester F Jacobson
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
General Electric Co
Original Assignee
General Electric Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by General Electric Co filed Critical General Electric Co
Priority to US517570A priority Critical patent/US3396265A/en
Priority to GB49882/66A priority patent/GB1113909A/en
Priority to FR84815A priority patent/FR1501568A/fr
Priority to NL6616769.A priority patent/NL156836B/xx
Priority to DE1966G0048833 priority patent/DE1565565B2/de
Priority to ES0335013A priority patent/ES335013A1/es
Priority to CH1867766A priority patent/CH459391A/de
Priority to BE691998D priority patent/BE691998A/xx
Priority to SE17945/66A priority patent/SE327025B/xx
Application granted granted Critical
Publication of US3396265A publication Critical patent/US3396265A/en
Assigned to BLACK & DECKER, INC., A CORP. OF DE reassignment BLACK & DECKER, INC., A CORP. OF DE ASSIGNS AS OF APRIL 27, 1984 THE ENTIRE INTEREST Assignors: GENERAL ELECTRIC COMPANY A NY CORP.
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B1/00—Details of electric heating devices
    • H05B1/02—Automatic switching arrangements specially adapted to apparatus ; Control of heating devices
    • H05B1/0202—Switches
    • H05B1/0213—Switches using bimetallic elements
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
    • G05D23/00—Control of temperature
    • G05D23/19—Control of temperature characterised by the use of electric means
    • G05D23/1906—Control of temperature characterised by the use of electric means using an analogue comparing device
    • G05D23/1913—Control of temperature characterised by the use of electric means using an analogue comparing device delivering a series of pulses
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
    • G05D23/00—Control of temperature
    • G05D23/19—Control of temperature characterised by the use of electric means
    • G05D23/20—Control of temperature characterised by the use of electric means with sensing elements having variation of electric or magnetic properties with change of temperature
    • G05D23/24—Control of temperature characterised by the use of electric means with sensing elements having variation of electric or magnetic properties with change of temperature the sensing element having a resistance varying with temperature, e.g. a thermistor
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H61/00—Electrothermal relays
    • H01H61/02—Electrothermal relays wherein the thermally-sensitive member is heated indirectly, e.g. resistively, inductively
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H5/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal non-electric working conditions with or without subsequent reconnection
    • H02H5/04—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal non-electric working conditions with or without subsequent reconnection responsive to abnormal temperature
    • H02H5/047—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal non-electric working conditions with or without subsequent reconnection responsive to abnormal temperature using a temperature responsive switch
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B3/00—Ohmic-resistance heating
    • H05B3/20—Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater
    • H05B3/34—Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater flexible, e.g. heating nets or webs
    • H05B3/342—Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater flexible, e.g. heating nets or webs heaters used in textiles
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B3/00—Ohmic-resistance heating
    • H05B3/20—Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater
    • H05B3/34—Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater flexible, e.g. heating nets or webs
    • H05B3/36—Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater flexible, e.g. heating nets or webs heating conductor embedded in insulating material
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B2203/00—Aspects relating to Ohmic resistive heating covered by group H05B3/00
    • H05B2203/014—Heaters using resistive wires or cables not provided for in H05B3/54
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B2203/00—Aspects relating to Ohmic resistive heating covered by group H05B3/00
    • H05B2203/017—Manufacturing methods or apparatus for heaters

Definitions

  • the present invention relates to controls and, more particularly, to controls which are used in electrically heated bedcover overtemperature control systems.
  • a further object of this invention is the provision of a control of the character indicated which provides accurate circuit control and wherein normal fluctuations in supply line voltage do not affect proper operation of the control.
  • I provide a control which includes a pair of thermally responsive elements each of which carries an electrical contact.
  • Auxiliary heating means are mounted in intimate heat transfer relation with the elements to cause actuation thereof in accordance with current flow through a temperature sensor material in an electrically heated bedcover control system.
  • the contacts are separated from each other when the bedcover is turned 0 and also when an overtemperature condition occurs in any portion of the bedcover.
  • a predetermined dif- 3,396,265 Patented Aug. 6, 1968 ference in heat supplied to the two thermally responsive elements causes the contacts to be engaged with each other.
  • I provide a heat dissipating member in intimate heat transfer relationship with one of the thermally responsive elements.
  • FIGURE 1 is a perspective view of a control box cut away to illustrate a preferred control relay embodied in the present invention
  • FIGURE 2 is an electrical schematic diagram of a control system using the relay illustrated at FIGURE 1;
  • FIGURE 3 is an exploded perspective view of the relay illustrated at FIGURE 1;
  • FIGURE 4 is a view along line 44 of FIGURE 3.
  • FIGURE 2 The specific electrical circuit illustrated by FIGURE 2 and described herein is not my invention, but forms the subject matter of the co-pending application of William D. Ryckman, Ser. No. 517,598, filed concurrently herewith and assigned to the General Electric Company, assignee of this application.
  • the invention herein is directed particularly to an improvement of the thermal switch of the control system.
  • FIGURES 1 and 3 there is illustrated a relay 10 mounted in a control box 11.
  • the relay comprises a pair of bimetallic blades 12 and 13 which carry switch contacts 14 and 15.
  • the switch contacts are secured near the ends 16 and 17 of the blades, and these ends are free to move under the influence of heat supplied to the blades
  • the opposite ends 18 and 19 of the blades are fixed with respect to each other through the medium of a mounting bracket 20 which is also used to mount the relay in the control box.
  • the mounting bracket includes a first member 21 which is stamped from steel or other material having good thermal transfer properties.
  • the end portion 19 of blade 13 is secured in intimate heat transfer relationship with the first member such as with rivets 22; and, because the member 21 has good thermal transfer properties, it functions as a heat dissipating member for bimetallic blade 13, as will be hereinafter referred to in greater detail.
  • the mounting bracket further includes a second member 23 which may be formed of the same material as the first member.
  • the blade 12 is separated from the second member 23 through the medium of a block 24 of thermally and electrically insulating plastic material, and rivets 25 are used to secure the blade to the block. Other rivets 2511 are used to secure the block 24 to the second member 23.
  • electrical heating resistors 26 and 27 are mounted in intimate thermal transfer relations-hip with the blades. These resistors may be made of a molded composition resistance material. To assure good thermal transfer between the resistors and the blades, mounting channels 28 and 29 are formed in the blades. These channels are formed by providing spaced slits in the blades and then deforming portions of the blades on opposite sides of the slits alternately in opposite directions from the plane of the blades.
  • the insulating block 24 includes a pair of arcuate projections 30 along the bottom surface thereof. These projections couple with grooves 31 formed in side walls of the first bracket mmeber 21 to provide means to initially pivot the bimetallic blade 12 with respect to bimetallic blade 13 for calibration purposes.
  • the assembly including the second member 23, blade 12, and insulating block 24 is mounted with respect to the first member 21 and blade 13 so that the projections 30 are in the grooves 31.
  • the blade 12 is then pivoted with respect to the blade 13 to achieve a desired gap between the two contacts 14 and 15.
  • the members 21 and 23 are secured together such as by welding, and the required gap is thereby fixed.
  • the rear end of the insulating block is provided with grooves 32 which accommodate lead wires.
  • the bimetallic blades are mounted in a manner to tolerate normal changes in ambient temperature without substantially changing the initial calibrated gap between the contacts. This may be accomplished by having surfaces 33 and 34 formed of the metal having a low coeflicient of thermal expansion, while the surfaces 35 and 36 (FIG. 4) are formed of the metal having a high coeflicient of thermal expansion. This temperature change toleration may be further assured by making the two bimetallic strips substantially identical to each other.
  • FIGURE 2 schematically illustrates an electric bed-cover control circuit utilizing this relay.
  • the operation of the system is as follows, assuming that power plug 37 has been plugged into an ordinary alternating current household outlet, and assuming that a female plug 38 extending from the control box is plugged into a male plug 39 extending from the bedcover 40, and also assuming that the blanket is cold: Manual switch 41 is closed and electric current follows a path from power lead 42 through heating resistor 27, conductor 43, heating resistor 26, and conductor 44 to power lead 45 on the other side of the line.
  • resistor 26 The resistance value of resistor 26 is greater than resistance 27; furthermore, bimetallic blade 13 loses heat faster than bimetallic blade 12 because of the heat dissipating number 21. Therefore, more heat is experienced by blade 12 than blade 13, and this causes bimetallic blade 12 to deflect a greater distance than blade 13 to close the initial gap between contacts 14 and 15. Current can now flow through heating wire 46 in the bedcover, assuming also that the contacts 47 and 48 of ambient responsive control 49 are engaged.
  • the ambient responsive control includes a bimetallic blade 50 which is adapted to be heated by heating resistor 51.
  • the contact 48 deflects to the left (as viewed at FIGURE 2) to open the circuit to the blanket heating wire 46.
  • the blade is cooled by the ambient temperature which once again causes the contacts 47 and 48 to be engaged, and this cycle continues to repeat itself.
  • the period of time that the contacts are engaged is therefore determined in part by the ambient temperature and in part by the setting of a control knob 52 by the user.
  • a layer 53 of temperature sensing material having a negative temperature coeflicient of impedance is located between the conductors 43 and 44, and the conductors with the temperature sensing material therebetween are disposed throughout the bedcover 40.
  • the layer has a uniform Wall thickness between the conductors of approximately .010 inch.
  • the material 53 may have an impedance on the order of 300,000 to 400,000 ohms between the conductors when it is at room temperature and so, for present purposes it is considered to be :an insulator. As the blanket heats up to normal operating temperatures at the blanket heater 46 of say 120 F., the impedance of layer 53 decreases to approximately 150,000 ohms.
  • the layer 53 is still considered to be an insulator because not enough current can flow through the sensor material between the conductors 43 and 44 to operate the relay 10. If, however, an overtemperature condition, which may be caused by inadvertent bunching or folding, exists in the blanket, the temperature sensed by the layer of material 53 increases even more. Before the temperature in any portion of the bedcover reaches dan- 4 gerous proportions, the impedance of the layer 53 drops to about 50,000 to 60,000 ohms. At the latter value of impedance the sensor material is considered to be a condoctor because it conducts current of control magnitude in the sense that it shunts enough current from resistor 26 to operate the relay.
  • the sensor layer 53 is in shunt only with the heater 26 and not with heater 27.
  • the current through resistor 27 increases so that bimetal 13 is now gaining heat, and the other bimetal 12 is losing heat, thereby causing the bimetallic blades to move away from each other, and the contacts are disengaged toopen the circuit to the electric heating wire 46.
  • the bedcover cools.
  • the contacts 14 and 15 will again be engaged. The cycle repeats itself until the cause of the overtemperature condition has been removed.
  • a suitable material for use in the layer 53 is plasticized polyvinyl chloride having, as an additive, approximately 0.75% stearyldimethylbenzylamrnonium chloride.
  • Other suitable materials are disclosed in US. Patent No. 2,846,560, Jacoby et al., issued on Aug. 5, 1958 and assigned to General Electric Company, assignee of the present application.
  • the closing of the contacts of the relay 10 is dependent on a sufficient diiference in heat to the bimetallic blades to close the gap between the contacts. I increase this differential, and thereby re; prise the time it takes for the contacts to close, by using the afore mentioned mounting bracket 21 as a thermal dissipating member to remove heat from the bimetallic blade 13.
  • the member 21 limits the amount of heat that the blade Will experience should there be a short circuit between conductors 43 and 44.
  • a control for an electrically heated bedcover or the like comprising:
  • thermosensor distributed over the area of said heating means and including a pair of conductors separated by :a layer of material having a negative temperature coefficient of impedance;
  • control as set forth in claim 1 including a thermally conducting mounting bracket for mounting said thermally responsive elements in a control box, and wherein said second thermally responsive element is thermally insulated from said mounting bracket.
  • thermally responsive elements comprise bimetallic blades mounted in face to face relationship for movement in the same direction under influence of heat.
  • a control for an electrically heated bedcover or the like comprising:
  • first and second bimetallic blades each having a fixed end and a movable end, said movable ends flexing in the same direction under the influence of heat;
  • a mounting bracket of thermally conducting material for mounting said blades in a control case, said mounting bracket including a first member connected to said first blade in intimate thermal transfer relationship therewith, a second member connected to said second blade and separated therefrom by a layer of insulating material, and means for initially pivotally connecting said first and second members to establish a predetermined gap between said contacts prior to rigidly connecting said first and second members;
  • pivotal connecting means includes an arcuate projection on said insulating block received in arcuate grooves in said first member of said bracket.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Automation & Control Theory (AREA)
  • Textile Engineering (AREA)
  • Control Of Resistance Heating (AREA)
  • Control Of Temperature (AREA)
  • Thermally Actuated Switches (AREA)
US517570A 1965-12-30 1965-12-30 Electrically heated bedcover overtemperature control Expired - Lifetime US3396265A (en)

Priority Applications (9)

Application Number Priority Date Filing Date Title
US517570A US3396265A (en) 1965-12-30 1965-12-30 Electrically heated bedcover overtemperature control
GB49882/66A GB1113909A (en) 1965-12-30 1966-11-08 Improvements in control systems for electrically heated devices
FR84815A FR1501568A (fr) 1965-12-30 1966-11-24 Perfectionnements aux dispositifs pour éviter la surchauffe d'articles du genre descouvertures chauffantes électriques
NL6616769.A NL156836B (nl) 1965-12-30 1966-11-29 Regelstelsel voor een elektrische deken.
DE1966G0048833 DE1565565B2 (de) 1965-12-30 1966-12-23 Uebertemperaturregler fuer eine elektrische bettdecke
ES0335013A ES335013A1 (es) 1965-12-30 1966-12-28 Un dispositivo de control para uso de un sistema de control del exceso de temperatura en una manta calentada electricamente.
CH1867766A CH459391A (de) 1965-12-30 1966-12-28 Ubertemperatur-Überwachungseinrichtung an einer elektrisch heizbaren Bettdecke
BE691998D BE691998A (xx) 1965-12-30 1966-12-30
SE17945/66A SE327025B (xx) 1965-12-30 1966-12-30

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US517570A US3396265A (en) 1965-12-30 1965-12-30 Electrically heated bedcover overtemperature control

Publications (1)

Publication Number Publication Date
US3396265A true US3396265A (en) 1968-08-06

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ID=24060340

Family Applications (1)

Application Number Title Priority Date Filing Date
US517570A Expired - Lifetime US3396265A (en) 1965-12-30 1965-12-30 Electrically heated bedcover overtemperature control

Country Status (9)

Country Link
US (1) US3396265A (xx)
BE (1) BE691998A (xx)
CH (1) CH459391A (xx)
DE (1) DE1565565B2 (xx)
ES (1) ES335013A1 (xx)
FR (1) FR1501568A (xx)
GB (1) GB1113909A (xx)
NL (1) NL156836B (xx)
SE (1) SE327025B (xx)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3487201A (en) * 1968-04-12 1969-12-30 Tesla Np Compensator for thermoelectric control circuit
US3628093A (en) * 1970-04-13 1971-12-14 Northern Electric Co Thermostat overheat protection system for an electric appliance such as a blanket
US3683151A (en) * 1971-02-26 1972-08-08 Fieldcrest Mills Inc Electrically heated bedcover with thermostatless overheat protection circuit and separate comfort control
US3814899A (en) * 1972-12-18 1974-06-04 Gen Electric Overtemperature control system
US4450496A (en) * 1979-08-16 1984-05-22 Raychem Corporation Protection of certain electrical systems by use of PTC device
US4575620A (en) * 1983-05-11 1986-03-11 Matsushita Electric Industrial Co., Ltd. Flexible heating wire

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4034185A (en) * 1975-09-02 1977-07-05 Northern Electric Company Electric blanket control circuit
GB1601126A (en) * 1977-10-11 1981-10-28 Dreamland Electrical Appliance Heating circuits

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2510038A (en) * 1947-01-17 1950-05-30 Landers Frary & Clark Electric blanket control
US2846560A (en) * 1957-05-31 1958-08-05 Gen Electric Heater wire
US2928927A (en) * 1958-02-10 1960-03-15 Chemstrand Corp Control circuit for heating device
US3114820A (en) * 1961-04-05 1963-12-17 Gen Electric Heat responsive control circuit
US3213329A (en) * 1963-04-30 1965-10-19 Gen Electric Temperature sensor system

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2510038A (en) * 1947-01-17 1950-05-30 Landers Frary & Clark Electric blanket control
US2846560A (en) * 1957-05-31 1958-08-05 Gen Electric Heater wire
US2928927A (en) * 1958-02-10 1960-03-15 Chemstrand Corp Control circuit for heating device
US3114820A (en) * 1961-04-05 1963-12-17 Gen Electric Heat responsive control circuit
US3213329A (en) * 1963-04-30 1965-10-19 Gen Electric Temperature sensor system

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3487201A (en) * 1968-04-12 1969-12-30 Tesla Np Compensator for thermoelectric control circuit
US3628093A (en) * 1970-04-13 1971-12-14 Northern Electric Co Thermostat overheat protection system for an electric appliance such as a blanket
US3683151A (en) * 1971-02-26 1972-08-08 Fieldcrest Mills Inc Electrically heated bedcover with thermostatless overheat protection circuit and separate comfort control
US3814899A (en) * 1972-12-18 1974-06-04 Gen Electric Overtemperature control system
US4450496A (en) * 1979-08-16 1984-05-22 Raychem Corporation Protection of certain electrical systems by use of PTC device
US4575620A (en) * 1983-05-11 1986-03-11 Matsushita Electric Industrial Co., Ltd. Flexible heating wire

Also Published As

Publication number Publication date
DE1565565A1 (de) 1970-06-25
ES335013A1 (es) 1967-11-16
CH459391A (de) 1968-07-15
FR1501568A (fr) 1967-11-10
DE1565565B2 (de) 1976-05-26
NL6616769A (xx) 1967-07-03
BE691998A (xx) 1967-05-29
NL156836B (nl) 1978-05-16
SE327025B (xx) 1970-08-10
GB1113909A (en) 1968-05-15

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Owner name: BLACK & DECKER, INC., 1423 KIRKWOOD HIGHWAY NEWARK

Free format text: ASSIGNS AS OF APRIL 27, 1984 THE ENTIRE INTEREST;ASSIGNOR:GENERAL ELECTRIC COMPANY A NY CORP.;REEL/FRAME:004349/0275

Effective date: 19840824

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