US3569888A - Thermally sensitive electric switches and actuating devices therefor - Google Patents

Thermally sensitive electric switches and actuating devices therefor Download PDF

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Publication number
US3569888A
US3569888A US822175A US3569888DA US3569888A US 3569888 A US3569888 A US 3569888A US 822175 A US822175 A US 822175A US 3569888D A US3569888D A US 3569888DA US 3569888 A US3569888 A US 3569888A
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United States
Prior art keywords
bimetal
mounting block
switch
tongue
secured
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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
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US822175A
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English (en)
Inventor
John C Taylor
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Otter Controls Ltd
Original Assignee
John C Taylor
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Publication date
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Publication of US3569888A publication Critical patent/US3569888A/en
Assigned to STRIX LIMITED, A COMPANY OF ISLE OF MAN reassignment STRIX LIMITED, A COMPANY OF ISLE OF MAN ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: TAYLOR, JOHN C.
Assigned to OTTER CONTROLS LIMITED reassignment OTTER CONTROLS LIMITED ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: STRIX LIMITED A COMPANY OF ISLE OF MAN
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H37/00—Thermally-actuated switches
    • H01H37/02—Details
    • H01H37/32—Thermally-sensitive members
    • H01H37/52—Thermally-sensitive members actuated due to deflection of bimetallic element
    • H01H37/54—Thermally-sensitive members actuated due to deflection of bimetallic element wherein the bimetallic element is inherently snap acting
    • H01H37/5418—Thermally-sensitive members actuated due to deflection of bimetallic element wherein the bimetallic element is inherently snap acting using cantilevered bimetallic snap elements

Definitions

  • thermoly sensitive actuating member comprising a sheet or strip of bimetal having a tongue released therefrom between two outer legs, said tongue being connected to the sheet or strip at one end and being free at its other end, and the said sheet or strip being stressed by drawing the said outer legs towards one another so that it is caused to buckle out of its original plane in two directions to form a stressed system which will move with changes in temperature between two positions on either side of an intermediate unstable position with a snap action.
  • bimetal actuating members are those referred to hereinafter as being of the kind described.
  • the present invention provides a snap-acting thermally sensitive switch-actuating device, comprising a bimetal actuating member of the kind described which member is secured to a mounting block therefor via at least one metal rod or rods being welded, brazed or soldered to the said outer legs of the bimetal member adjacent the free end of the said tongue thereof.
  • switch-actuating device may be arranged, in use, for the movement of its bimetal member with changes in temperature to operate switch contacts remote therefrom in any convenient fashion, e.g. by means of a pushrod or pull rod for example.
  • the bimetal actuating member may be of U-shape having its two arms embedded in the mounting block.
  • the outer legs of the bimetal sheet or strip may then be secured to the respective ends of the rod where its arms protrude from the mounting block, the crosspiece of the U-shaped rod being on the opposite side of the mounting block from the bimetal sheet or strip.
  • the outer legs of the bimetal sheet or strip may be secured to the corners of such U-shaped rod, i.e.
  • the central part of thecrosspiece of the U may then be displaced, e.g. bowed or joggled, out of the plane of the arms thereof so as not to interfere with the movement of the bimetal member between its hot" and cold positions with change of temperature.
  • the outer legs of the bimetal sheet or strip will be secured respectively to end regions of the two rods protruding from the mounting block.
  • the said metal rod or rods may be embedded in and extend from a sin gle face of the mounting block without necessarily passing through the block.
  • the switch actuating device of this form of the invention may be mounted on two metal rods as aforesaid which rods pass completely through the mounting block, the other ends of the rods constituting or being provided with terminals for the connection of the bimetal member in an electric circurt.
  • the invention provides a snapacting thermally sensitive electric switch including a bimetal switch-actuating member of the kind described which member is secured to amounting block therefor via at least one metal rod embedded in said mounting block, two portions of said rod or rods being welded, brazed or soldered to the said outer legs of the bimetal member adjacent the free end of the said tongue thereof, at least one fixed switch contact secured to said mounting block, and a movable switch contact arranged to be operated directly or indirectly by movement of said bimetal actuating member with changes in its temperature.
  • the bimetal actuating member of such a switch may be secured to the mounting block via either one or two metal rods as described above.
  • the or each fixed contact of the switch may be secured to the said mounting block in any of a number of ways.
  • it could be mounted on a metal plate embedded in or otherwise fixed to the mounting block.
  • the or each such fixed contact is, like the bimetal actuating member, secured to a metal rod embedded in the block, which rod may extend through the block and have a portion thereof remote from the contact constituting or mounting a switch terminal associated with such fixed contact.
  • the movable contact of the switch is to be operated indirectly by the bimetal actuating member such contact could also be mounted, e.g. by a spring strip, on a metal rod embedded in the said mounting. block and extending therethrough to provide or mount a further terminal of the switch.
  • the bimetal actuating member may itself carry the movable contact of the switch so as to operate such contact directly, e.g. by having the contact mounted on the free end of the tongue of the bimetal sheet or strip, in which case such actuating member will be arranged to be connected in the circuit to be controlled in use and the or one of the metal rods which mounts such bimetal member may be extended through the mounting block to constitute or mount a switch terminal associated with the said movable contact.
  • the bimetal actuating member thereof is secured to the said mounting block by means of two metal rods permanently embedded in the block, one of which passes completely therethrough to provide one terminal of the switch at the end of the rod remote from the bimetal member.
  • the movable contact is mounted on the tongue of the bimetal member whilst a fixed switch contact is provided on one end of a further metal rod embedded in saidmounting block and extending therethrough to provide the other switch terminal, the fixed contact overlying the movable contact on the free end of the tongue of the bimetal sheet or strip.
  • another metal rod is embedded in the mounting block on the other side of the bimetal member to provide a stop defining the position to which the said tongue moves when the contacts are broken.
  • the last-mentioned rod could carry a second fixed contact and be extended through the mounting block to provide a terminal associated with the latter contact.
  • the mounting block is moulded with suitable holes for the reception of such rods and of such a diameter as to make the rods a tight interference fit therein; each rod is preferably slightly deformed at the appropriate part of its length to form splines thereon before being forced into its hole in the mounting block, so that the splines on the rod bite into the wall of the hole and hold the rod firmly in position.
  • the said rods may be of various cross-sectional shapes, but the operation of welding or otherwise securing the rod to the face of the bimetal sheet or strip is facilitated most of all if there is line contact between such parts.
  • the rods are of cylindrical form. They may be formed of any suitable metallic material; brass rods are very convenient to use but are comparatively expensive, and it is therefore preferred to use a less expensive material such as copper-coated steel.
  • switches may be embodying the broad principles of the present invention, in addition to the comparatively simple single-pole and changeover switches briefly mentioned above.
  • the invention is by no means limited to switches incorporating only a single bimetal actuating member of the kind described, as the convenience and reliability of the novel manner of mounting such members herein disclosed considerably facilitates the building up of complex assemblies of such members on a single mounting block, with both the actuating members and their various contacts interconnected in any desired way to achieve particular effects in operation.
  • metal rods embedded in the mounting block is not limited solely to providing the means for securing the bimetal actuating member(s) and contacts of a switch assembly to the block; such rods may also be employed with advantage to provide the desired electrical connections between the various elements of complex switch assemblies, or to carry heaters for controlling the operation of the bimetal members.
  • the mounting block itself may of course take various shapes; in a very simple form where it carries a single bimetal actuating member it may comprise a cylindrical block having two opposite flat faces from one of which said member extends, whilst in more complex applications the block may if desired be especially shaped to fit into a desired location in apparatus to be controlled. It will usually be formed of insulating material, e.g. a suitable plastic, but this is not essential in some cases as, for example, where a simple switch actuating device dependent for its operation on ambient temperature is provided.
  • FIG. 1 is a perspective view of a snap-acting thermally sensitive electric switch according to the invention
  • FIG. 2 is medial cross-sectional view of the switch of FIG. 1, taken on the line II-II;
  • FIG. 3 is a plan view of a snap-acting thermally sensitive switch-actuating device according to the invention.
  • FIG. 4 is plan view of a modified form of the device of FIG. 3.
  • FIGS. 1 and 2 comprises a snap-acting thermally sensitive electric switch in the form of a simple circuit breaker, including a bimetal actuating member of the kind described which is to be connected in an electric circuit to be controlled by the switch.
  • the bimetal actuating member comprises a rectangular sheet of bimetal 1 from which a U-shaped portion has been removed to define a central tongue 2 flanked by two outer legs 3, such legs being joined by a bridge portion 4 adjacent the free end of the tongue 2.
  • Such bridge portion is deformed at 5 by a crimping operation so as to draw the two outer legs 3 towards one another and thus to buckle the sheet 1 out of its original plane whereby it will snap between two positions on either side of an intermediate unstable position with changes in temperature.
  • FIG. 2 the position of the tongue 2 in the cold" condition of the bimetal sheet is shown in full lines whilst its position in the hot" condition of the sheet is shown in ghost lines.
  • a movable contact 6 of the switch is mounted on the free end of the tongue 2.
  • the bimetal sheet 1 is secured to a mounting block 7 in the form of a thick disc of moulded plastics insulating material having two opposite parallel faces 8 and 9.
  • Two copper-coated steel rods 10 and 11 are embedded in the mounting block 7 at right angles to the said opposite faces thereof, the rod 10 extending completely through the block and having its ends protruding on both sides thereof, whilst the other rod 11 had only one end protruding.
  • two respective ends 12 and 13 of the rods 10 and 11 protrude from the front face 8 of the mounting block 7 at right angles thereto and substantially on a common diameter of such face, whilst the other end 14 of the rod 10 protrudes from the rear 9 of the block to provide one terminal of the switch.
  • the rods 10 and 11 are embedded in the mounting block 7 by moulding two holes in the block of such a diameter that the rods are a tight interference fit in the holes, and slightly deforming the rods at appropriate positions in their lengths so as to form splines 15 thereon (see FIG. 2). The rods are then forced into the holes so that the splines bite into the walls thereof to hold the rods in position.
  • the bimetal sheet 1 is welded to the two ends 12 and 13 of the rods 10 and 11 via one face of the sheet, at the respective end regions of its outer legs 3 adjacent the free end of the tongue 2, so that such member extends from the front face 8 of the mounting block in cantilever fashion, the said ends of the rods lying adjacent and parallel with the side edges of the plate.
  • a fixed contact 16 of the switch is mounted on the end of a third copper-coated steel rod 17 similarly embedded in the mounting block 7, which rod passes completely through the block and extends from the front face 8 thereof to a greater extent than the two rods 10 and 11 so as to overlie the movable contact 6 on the free end of the tongue 2 of the bimetal sheet.
  • the other end 18 of the rod 17 extends from the rear face 9 of the mounting block as to provide the second terminal of the switch.
  • a fourth copper-coated steel rod 19 is embedded in the mounting block on the opposite side of the bimetal sheet 1 from the rod 17 and extends only from the front face 8 of the block so as to underlie the tongue 2 of the bimetal sheet to provide a stop defining the position to which such tongue moves when the bimetal actuating member 1 operates to break the switch contacts.
  • the invention provides a circuit breaker switch connectable in a circuit via the terminals provided by thoserods l0 and 17 which extend from the rear face 9 of the mounting block 7, and which will be operative to break such circuit when the bimetal actuating member operates with rising temperature.
  • FIG. 3 shows a snap-acting thermally sensitive switch actuating device according to the invention, which simply comprises the switch of FIGS. 1 and 2 with the rods 17 and 19 and the switch contacts 6 and 16 omitted, and the rod 11 lengthened to protrude from the rear face 9 of the block 7. All of the other parts, being the same as in FIGS. 1 and 2, are given the same reference numerals as in those Figures and will not be described again.
  • the device of FIG. 3 may be used to actuate switch contacts in any desired manner upon operation of the bimetal actuating member 1 with changes in temperature, for example by connecting the tongue 2 of the device to the movable contact of an associated switch by means of a simple push and/or pull rod.
  • the device may operate in response to ambient temperature or may be connected in an electric circuit by way of the free ends of the rods 10 and 11 so as to be current sensitive.
  • FIG. 4 shows a modification of the device of FIG. 3 in which the two rods 10 and 11 are replaced by a single substantially U-shaped rod 20 whose respective arms 21 and 22 are embedded in the block 7 and serve the same functions as the rods and 11 of FIG. 3.
  • the device may if desired be mounted via the crosspiece 23 of the U-shaped rod 20.
  • the crimped bridge portion 4 of the bimetal sheet 1 may be omitted and the sheet stressed simply by means of its connection with its mounting rod.
  • the sheet may be held in a suitable jig with the free ends of its outer legs 3 drawn towards one another to the desired extent whilst the welds are being ef fected; alternatively the legs could be welded to the rods before the latter are embedded in the mounting block and the legs then drawn towards one another by suitable positioning of the rods in the block.
  • the invention provides switch-actuating devices (and switches) whose bimetal actuating member is mounted in a very simple, robust and convenient manner which facilitates manufacture and provides great reliability in operation.
  • a snap-acting thermally sensitive switch-actuating device comprising: a thermally sensitive actuating member in the form of a sheet of bimetal having a tongue released therefrom between two outer legs, said tongue being connected to the sheet at one end and being free at its other end, the said sheet being stressed so that it is buckled out of its original plane in two directions to form a stressed system which moves with changes in temperature between two oppositely buckled conditions with a snap action; a mounting block for said bimetal actuating member; and metal rod means embedded in and projecting from a face of said mounting block, two spaced side surface portions of said rod means being fixedly secured to said outer legs of said bimetal actuating member, by welding or the like, adjacent the free end of said tongue, to secure the bimetal actuating member to said mounting block.
  • a snap-acting thermally sensitive electric switch comprising: a thermally sensitive actuating member in the form of a sheet of bimetal having a tongue released therefrom between two outer legs, said tongue being connected to the sheet at one end and being free at its other end, the said sheet being stressed so that it is buckled out of its original plane in two directions to form a stressed system which moves with changes in temperature between two oppositely buckled conditions with a snap action;, a mounting block for said bimetal actuating member; metal rod means embedded in and projecting from a face of said mounting block, two spaced side surface portions of said rod means being fixedly secured to said outer legs of said bimetal actuating member, by welding or the like, adjacent the free end of said tongue, to secure the bimetal actuating member to said mounting block; a fixed switch contact secured to said mounting block; and a movable switch contact arranged to be operated by movement of said bimetal actuating member with changes in temperature.
  • a switch as claimed in claim 1] which has only one fixed switch contact and wherein-another metal rod is embedded in the mounting block and extends on the side of the bimetal opposite from said fixed switch contact to provide a stop defining the position to which the said tongue moves when the switch contacts are broken.

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  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Thermally Actuated Switches (AREA)
US822175A 1968-05-15 1969-05-06 Thermally sensitive electric switches and actuating devices therefor Expired - Lifetime US3569888A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB23158/68A GB1255175A (en) 1968-05-15 1968-05-15 Improvements in thermally sensitive electric switches and actuating devices therefor

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US3569888A true US3569888A (en) 1971-03-09

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US822175A Expired - Lifetime US3569888A (en) 1968-05-15 1969-05-06 Thermally sensitive electric switches and actuating devices therefor

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US (1) US3569888A (de)
DE (1) DE1924701C3 (de)
GB (1) GB1255175A (de)
SE (1) SE369798B (de)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4013988A (en) * 1976-01-19 1977-03-22 Therm-O-Disc Incorporated Hermetically sealed motor protector
US4151501A (en) * 1976-05-07 1979-04-24 Taylor John C Terminal mounting means for thermally actuated switches
US4236135A (en) * 1978-10-02 1980-11-25 Therm-O-Disc, Incorporated Sealed motor protector
US4376925A (en) * 1980-01-16 1983-03-15 Taylor John C Switch units for electric immersion heaters
DE3401968A1 (de) * 1983-01-21 1984-07-26 Otter Controls Ltd., Buxton, Derbyshire Schutzschalter fuer elektromotoren
US4528538A (en) * 1984-01-13 1985-07-09 Andersen James H Combined switch and circuit breaker
DE3526785C1 (de) * 1985-07-26 1986-07-17 Ellenberger & Poensgen Gmbh, 8503 Altdorf Druckknopfbetaetigter UEberstromschutzschalter
US20050134424A1 (en) * 2003-12-19 2005-06-23 Albert Huang Bimetallic strip for a circuit breaker
US20170294281A1 (en) * 2014-10-20 2017-10-12 Uchiya Thermostat Co., Ltd. Temperature switch
WO2018236226A1 (en) * 2017-06-21 2018-12-27 Introl Ip Limited ELECTRIC SWITCH AND SWITCHING BLADE THEREFOR

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3104827A1 (de) * 1981-02-11 1982-08-19 Limitor AG, 8022 Zürich "bimetalltemperaturschalter"

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB657434A (en) * 1949-02-07 1951-09-19 Eric Hardman Taylor Improvements in or relating to snap-action actuating members for electric switches
US2777032A (en) * 1953-05-12 1957-01-08 Burch Parkhurst Associates Snap switch and blade therefor
GB901881A (en) * 1958-05-02 1962-07-25 Eric Hardman Taylor Improvements in or relating to thermally controlled electric switches
GB903807A (en) * 1960-04-04 1962-08-22 Eric Hardman Taylor Improvements in or relating to thermosensitive switches
US3213246A (en) * 1962-04-09 1965-10-19 Texas Instruments Inc Protective encapsulation for electrical devices
US3361883A (en) * 1966-11-01 1968-01-02 Theodore Brassard Jr. Calibrated thermostatic switch and method for calibrating the same including welded lug and recess means

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB657434A (en) * 1949-02-07 1951-09-19 Eric Hardman Taylor Improvements in or relating to snap-action actuating members for electric switches
US2777032A (en) * 1953-05-12 1957-01-08 Burch Parkhurst Associates Snap switch and blade therefor
GB901881A (en) * 1958-05-02 1962-07-25 Eric Hardman Taylor Improvements in or relating to thermally controlled electric switches
GB903807A (en) * 1960-04-04 1962-08-22 Eric Hardman Taylor Improvements in or relating to thermosensitive switches
US3213246A (en) * 1962-04-09 1965-10-19 Texas Instruments Inc Protective encapsulation for electrical devices
US3361883A (en) * 1966-11-01 1968-01-02 Theodore Brassard Jr. Calibrated thermostatic switch and method for calibrating the same including welded lug and recess means

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4013988A (en) * 1976-01-19 1977-03-22 Therm-O-Disc Incorporated Hermetically sealed motor protector
US4151501A (en) * 1976-05-07 1979-04-24 Taylor John C Terminal mounting means for thermally actuated switches
US4236135A (en) * 1978-10-02 1980-11-25 Therm-O-Disc, Incorporated Sealed motor protector
US4376925A (en) * 1980-01-16 1983-03-15 Taylor John C Switch units for electric immersion heaters
US4532488A (en) * 1983-01-21 1985-07-30 Otter Controls Limited Electric motor protection switches
DE3401968A1 (de) * 1983-01-21 1984-07-26 Otter Controls Ltd., Buxton, Derbyshire Schutzschalter fuer elektromotoren
US4528538A (en) * 1984-01-13 1985-07-09 Andersen James H Combined switch and circuit breaker
DE3526785C1 (de) * 1985-07-26 1986-07-17 Ellenberger & Poensgen Gmbh, 8503 Altdorf Druckknopfbetaetigter UEberstromschutzschalter
US4667175A (en) * 1985-07-26 1987-05-19 Ellenberg & Poensgen Gmbh Overload protective circuit breaker
US20050134424A1 (en) * 2003-12-19 2005-06-23 Albert Huang Bimetallic strip for a circuit breaker
US20170294281A1 (en) * 2014-10-20 2017-10-12 Uchiya Thermostat Co., Ltd. Temperature switch
US10163593B2 (en) * 2014-10-20 2018-12-25 Uchiya Thermostat Co., Ltd. Temperature switch
WO2018236226A1 (en) * 2017-06-21 2018-12-27 Introl Ip Limited ELECTRIC SWITCH AND SWITCHING BLADE THEREFOR

Also Published As

Publication number Publication date
SE369798B (de) 1974-09-16
DE1924701C3 (de) 1975-04-17
DE1924701A1 (de) 1969-11-27
DE1924701B2 (de) 1974-08-15
GB1255175A (en) 1971-12-01

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Legal Events

Date Code Title Description
AS Assignment

Owner name: STRIX LIMITED, BAY VIEW ROAD, PORT ERIN, ISLE OF M

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:TAYLOR, JOHN C.;REEL/FRAME:004189/0967

Effective date: 19830719

AS Assignment

Owner name: OTTER CONTROLS LIMITED, OTTERS OLE, MARKET ST., B

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:STRIX LIMITED A COMPANY OF ISLE OF MAN;REEL/FRAME:004212/0462

Effective date: 19830906