|Publication number||US3763454 A|
|Publication date||Oct 2, 1973|
|Filing date||Feb 22, 1972|
|Priority date||Feb 22, 1972|
|Publication number||US 3763454 A, US 3763454A, US-A-3763454, US3763454 A, US3763454A|
|Original Assignee||Tektronix Inc|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (4), Referenced by (57), Classifications (8)|
|External Links: USPTO, USPTO Assignment, Espacenet|
United States Patent 1 Zandonatti 1 1 Oct. 2, 1973 THERMAL SWITCH Primary Examiner-Harold Broome  lnventor: Raymond A. Zandonatti, Beaverton, La Rue 57 ABSTRACT  Assignee: Tektronix, Inc., Beaverton, Oreg. I
A thermal switch is provided on an insulating support  Fled: 1972 member which includes conductive means carried 2 APP] 22 09 thereby with two of the conductive means defining stationary contact means at ends thereof spaced from each other. Movable contact means has one end se-  [1.8. CI. 337/404, 337/407 cured to one of the stationary Contact means and the  Int. Cl. H0lh 37/76 free end thereof extends over the other of the station  Field of Search 337/403, 401, 404, my Contact means Resistive means has one end eoh 337/405, 406, 0 nected to one of the two of the conductive means and another end connected to a further conductive means.  References Cited Means is provided between the stationary contact UNlTED STATES PATENTS means and the free end of the movable contact means 530 430 2 g94 Klein 337/403 maintaining the contact means in electrical engage- 2,548,491 4/1951 Peek, Jr. 337/184 ment and to cause the contact means'to become disen- 1',398,153 11/1921 Reichard... 337/404 gaged when the heat generated by the resistive means 3,301,981 H1967 Urani .1 337/404 exceeds a predetermined limit 8 Claims, 5 Drawing Figures THERMAL SWITCH BACKGROUND OF THE INVENTION Electronic circuitry is typically utilized for testing purposes and it will operate within prescribed voltage limits. In using such circuitry, operators will inadvertently apply the circuitry to voltage areas in excess of the prescribed voltage limits and this will of course damage the circuitry thereby rendering the testing device incapable of further use and requiring its replacement.
One way to protect electrical circuitry is to use a fuse, but it will have to be replaced if it blows. This is expensive and time consuming as well as too large for thick film circuits.
Another way to protect electrical circuitry is to use a bimetallic member which will open the circuit when the current exceeds a certain value. Use of bimetallic members is expensive.
The present invention overcomes these drawbacks by providing a thermal switch in circuitry which will open the circuit when a predetermined temperature is reached which is determined by the current flowing therein and it can be closed again thereby enabling the circuitry to be reused.
An object of the present invention is to provide a thermal switch in an electronic or electrical circuit which will open when the current exceeds a predetermined level.
Another object of the present invention is a thermal switch for an electrical or electronic circuit which can be closed again without replacing any parts.
A further object of the present invention is the provision of a thermal switch which precisely operates at a predetermined temperature.
An additional object of the present invention is to provide a thermal switch that is inexpensive for use in connection with electrical or electronic circuitry.
A still further object of the present invention is a thermal switch having the central portion of resistor means disposed in close proximity to the low melting point solder which maintains the movable contact means in electrical engagement with the stationary contact means.
BRIEF DESCRIPTION OF DRAWINGS Other objects and advantages of the present invention will be apparent from the detailed description of preferred embodiments thereof and from the attached drawings of which:
FIG. I is a top plan view of a part of a substrate on which a thermal switch is located;
FIG. 2 is a side elevational view of FIG. 1 with the movable contact member in the open position;
FIG. 3 is a top plan view of an alternative embodiment of the invention;
FIG. 4 is a top plan view of a further embodiment of the invention; and
FIG. 5 is a view taken along lines 5 5 of FIG. 4.
DETAILED DESCRIPTION OF PREFERRED AND OTHER EMBODIMENTS The present invention is described in conjunction with a hybrid solid state circuit, but it is to be understood that the invention can be used on macrominiature circuits, etched circuit board circuitry and other circuitry of this general construction.
Turning now to FIGS. I and 2, a substrate I is shown which is generally made of aluminum oxide or some suitable dielectric material. Conductive members 2, 3 and 4 are carried by substrate 11. Conductive members 2 and 4 are connected to other components and other conductive members would be located on substrate 1 and these are not shown in the interest of brevity as well as not being essential to the invention. Ends of conductive members 2 and 3 are spaced from each other and they are bridged by a switch member 5 having one end secured to either end of conductive members 2 or 3 via welding or in any other conventional manner.
As can be discerned from FIG. 2, switch member 5 is shown in its open position and it is made from a suitable material having spring characteristics which is initially formed having an arcuate configuration. The material from which switch member 5 can be made is generally beryllium copper, phosphor bronze, silicon bronze, steel, or any other conductive material having the desirable spring characteristics.
Low temperature solder 6 having a predetermined melting point is placed at the end of either conductive member 2 or 3 and the free end of switch member 5 is soldered in position thereby connecting conductive members 2 and 3. Solder t3 is a conventional solder and it is selected in accordance with the melting point at which the switch means will open. The switch means is defined as stationary contact means comprising one of the ends of conductive members 2 or 3, the free end of switch member 5 and the solder 6 of a predetermined melting point.
A resistor 7 is connected between a section 8 of conductive member 3 and an end of conductive member 4 and its center is disposed in close proximity to the soldered end of the switch means and the reason for this is that the hotest point of the resistor 7 is at or about its center and this will direct the heat right at the soldered end. It is desired that substrate l have proper thermal conductivity to conduct the heat being generated by resistor 7 toward solder 6.
In operation, the switch means is closed by soldering the free end of switch member 5 to the end of conducrent passing therethrough and resistor 7 remains at or below a predetermined level, solder 6 will not melt and normal circuit operation will continue.
If the current exceeds the predetermined level, the heat being generated by resistor 7 causes the solder 6 to melt and the switch means opens due to its spring characteristics thereby preventing any damage to the circuitry on substrate )1. In order to reestablish the circuit, the solder 6 is reheated and the free end of switch member 5 is resoldered onto the end of conductive member 2 or 3 and the circuitry can be reused without having to be replaced. Thus, the switch means and the resistor in series therewith constitute a reuseable thermal switch means to prevent excessive voltages from permanently damaging electrical circuitry means.
FIG. 3 illustrates an alternative embodiment of the thermal switch wherein resistor 7a is disposed under switch member 5a and a thin piece of electrically insulating material 9 is secured over the central portion of resistor 7a in order to prevent any shorting between switch member 5a and resistor 71;. As can be discerned, the center of resistor 7a is positioned in close proximity to the soldered end of switch member 5a.
FIGS. 4 and 5 illustrate another embodiment of the invention wherein conductive member 3b extends through opening in substrate 1b and has a section 8b extending along the bottom surface of substrate 1b in alignment with conductive member 3b. Resistor 7b connects conductive member 4b with section 8b, and it is disposed in alignment with switch section Sb which connects conductive members 2b and 3b so that the central portion of resistor 7b is disposed in close proximity to the soldered end.
While there have been shown and described embodiments of the present invention, it will be apparent to those skilled in the art that many changes and modifications may be made without departing from the broader aspects of the invention; therefore, it is intended that the appended claims cover all such changes and modifications as fall within the true spirit and scope of the present invention.
The invention is claimed in accordance with the following:
1. A thermal switch comprising:
a hybrid solid state means including a substrate of dielectric materialhaving first, second and third conductive means secured on surface means thereof; a switch member of resilient material having a first end secured to said first conductive means and a second end disposed along said second conductive means; I
electrically conductive heat-softenable material securing said second end of said switch member to said second conductive means; and
resistive means having one end connected to said third conductive means and another end connected to said first or second conductive means and being disposed adjacent said switch member, said electrically conductive heat softenable material being softened upon heat generated by said resistive means reaching a predetermined limit thereby causing said second end of said switch member to move free of said second conductive means.
2. A thermal switch according to claim 1 wherein said switch member comprises an arcuate shape in its normally open position.
3. A thermal switch according to claim 1 wherein said resistive means has its central section disposed adjacent and in alignment with said heat-softenable material.
4. A thermal switch according to claim 1 wherein said resistive means extends parallel with respect to said switch member and the central portion of said resistive means is disposed adjacent said heat-softenable material.
5. A thermal switch according to claim 1 wherein said resistive means is disposed under said switch member and the central portion of said resistive means is disposed adjacent said heat-softenable material.
6. A thermal switch according to claim 5 wherein insulative means is disposed between said switch member and said resistive means.
7. A thermal switch according to claim 5 wherein said resistive means extends at a right angle with respect to said switch member.
8. A thermal switch according to claim 1 wherein said resistive means is disposed on another surface means opposite to said surface means on which said switch member is located and a central portion of said resistive means is disposed in alignment with said heatsoftenable material.
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US530430 *||May 19, 1894||Dec 4, 1894||Thermal circuit-breaker|
|US1398153 *||Mar 3, 1921||Nov 22, 1921||Reichard Walter V||Thermal circuit-closer|
|US2548491 *||Jan 28, 1950||Apr 10, 1951||Sylvania Electric Prod||Low-current fuse|
|US3301981 *||Jan 28, 1966||Jan 31, 1967||Mc Graw Edison Co||Protectors for electric circuits|
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US4423401 *||Jul 21, 1982||Dec 27, 1983||Tektronix, Inc.||Thin-film electrothermal device|
|US4494104 *||Jul 18, 1983||Jan 15, 1985||Northern Telecom Limited||Thermal Fuse|
|US5084691 *||Oct 1, 1990||Jan 28, 1992||Motorola, Inc.||Controllable fuse|
|US5192937 *||Dec 18, 1991||Mar 9, 1993||Dong A Electric Parts Co., Ltd.||Resistance unit for motor speed control|
|US5303402 *||Mar 9, 1992||Apr 12, 1994||Motorola, Inc.||Electrically isolated metal mask programming using a polysilicon fuse|
|US5363083 *||Jun 11, 1993||Nov 8, 1994||Roederstein Spezialfabriken Fuer Bauelemente Der Elektronik Und Kondensatoren Der Starkstromtechnik Gmbh.||Temperature responsive, electric overcurrent protection module|
|US5612662 *||Feb 7, 1995||Mar 18, 1997||Siemens Aktiengesellschaft||Thermal fuse and method for its activation|
|US5793274 *||Nov 1, 1996||Aug 11, 1998||Bourns, Inc.||Surface mount fusing device|
|US6198184 *||Jan 7, 1998||Mar 6, 2001||Zexel Corporation||Brushless motor|
|US6342827 *||Jun 18, 1998||Jan 29, 2002||Tyco Electronics Logistics Ag||Thermal fuse for fixing on a circuit substrate|
|US6348851 *||Aug 13, 1999||Feb 19, 2002||Renata A.G.||Breaker switch and battery including the same|
|US6445276 *||Mar 4, 1999||Sep 3, 2002||Trw Automotive Electronics & Components Gmbh & Co. Kg||Electrical fuse for use in motor vehicles|
|US6664885 *||Aug 31, 2001||Dec 16, 2003||Adc Telecommunications, Inc.||Thermally activated latch|
|US7265653 *||Aug 16, 2002||Sep 4, 2007||Wickmann-Werke Gmbh||Method of providing a protective component with an adjusted time characteristic of the thermal transfer from a heating element to a fusible element|
|US7469831||Oct 27, 2006||Dec 30, 2008||Gsi Group Corporation||Laser-based method and system for processing targeted surface material and article produced thereby|
|US7864024 *||Mar 28, 2006||Jan 4, 2011||Conti Temic Microelectronic Gmbh||Electronic assembly having spring-loaded contact bridge with fuse function|
|US7911314 *||Jul 21, 2007||Mar 22, 2011||Alexander Dauth||Electric circuit with thermal-mechanical fuse|
|US8143991 *||Jun 30, 2009||Mar 27, 2012||Chin-Chi Yang||Current and temperature overloading protection device|
|US8531263 *||Nov 23, 2010||Sep 10, 2013||Littelfuse, Inc.||Circuit protection device|
|US8665057||Oct 7, 2010||Mar 4, 2014||Conti Temic Microelectronic Gmbh||Electronic assembly having stressable contact bridge with fuse function|
|US8767368 *||Mar 2, 2009||Jul 1, 2014||Dexerials Corporation||Protective element and method for producing the same|
|US8941461||Feb 2, 2011||Jan 27, 2015||Tyco Electronics Corporation||Three-function reflowable circuit protection device|
|US9266728 *||Oct 22, 2014||Feb 23, 2016||Intelligent Energy Limited||Hydrogen producing fuel cartridge and methods for producing hydrogen|
|US9276278||Oct 22, 2014||Mar 1, 2016||Intelligent Energy Limited||Hydrogen producing fuel cartridge|
|US9455106 *||Feb 2, 2011||Sep 27, 2016||Littelfuse, Inc.||Three-function reflowable circuit protection device|
|US9524844 *||Jul 19, 2013||Dec 20, 2016||Infineon Technologies Ag||Fuse arrangement and a method for manufacturing a fuse arrangement|
|US9620318 *||Aug 6, 2012||Apr 11, 2017||Littlefuse, Inc.||Reflowable circuit protection device|
|US9620321 *||Aug 12, 2015||Apr 11, 2017||Borgwarner Ludwigsburg Gmbh||Fuse for an electrical circuit and printed circuit board having a fuse|
|US20050062577 *||Aug 16, 2002||Mar 24, 2005||Manfred Rupalla||Method for producing a protective component using an adjusted time response of the thermal transmission from a heating element to a fusible element|
|US20080073438 *||May 10, 2007||Mar 27, 2008||Gsi Group Corporation||Laser-based method and system for processing targeted surface material and article produced thereby|
|US20090027156 *||Mar 28, 2006||Jan 29, 2009||Roberto Schlenker||Electronic Assembly|
|US20100045421 *||Jul 21, 2007||Feb 25, 2010||Alexander Dauth||Electric Circuit With Thermal-Mechanical Fuse|
|US20100277268 *||Jan 6, 2009||Nov 4, 2010||Peter Ireman||Thermal safety device|
|US20100328017 *||Jun 30, 2009||Dec 30, 2010||Chin-Chi Yang||Current and temperature overloading protection device|
|US20110050386 *||Oct 7, 2010||Mar 3, 2011||Roberto Schlenker||Electronic Assembly Having Stressable Contact Bridge with Fuse Function|
|US20110121936 *||Nov 23, 2010||May 26, 2011||Littelfuse, Inc.||Circuit protection device|
|US20110211284 *||Mar 2, 2009||Sep 1, 2011||Sony Chemical & Information Device Corporation||Protective element and method for producing the same|
|US20120194315 *||Feb 2, 2011||Aug 2, 2012||Matthiesen Martyn A||Three-Function Reflowable Circuit Protection Device|
|US20130200984 *||Aug 6, 2012||Aug 8, 2013||Tyco Electronics Corporation||Reflowable Circuit Protection Device|
|US20140158334 *||Jun 21, 2012||Jun 12, 2014||Commissariat A L'energie Atomique Et Aux Ene Alt||Thermal management system with variable-volume material|
|US20140232511 *||Aug 3, 2012||Aug 21, 2014||Phoenix Contact Gmbh & Co. Kg||Thermal overload protection apparatus|
|US20150022310 *||Jul 19, 2013||Jan 22, 2015||Infineon Technologies Ag||Fuse arrangement and a method for manufacturing a fuse arrangement|
|US20150044131 *||Oct 22, 2014||Feb 12, 2015||Intelligent Energy Inc.||Hydrogen producing fuel cartridge and methods for producing hydrogen|
|US20150206679 *||Jan 23, 2015||Jul 23, 2015||Johnson Electric S.A.||Voltage controller for an electric fan|
|US20160049275 *||Aug 12, 2015||Feb 18, 2016||Borgwarner Ludwigsburg Gmbh||Fuse for an electrical circuit and printed circuit board having a fuse|
|CN102771036A *||Jan 20, 2011||Nov 7, 2012||博泽沃尔兹堡汽车零部件有限公司||Electric motor for driving a motor vehicle component|
|CN102771036B *||Jan 20, 2011||Jan 21, 2015||博泽沃尔兹堡汽车零部件有限公司||Electric motor for driving a motor vehicle component|
|DE3234826A1 *||Sep 21, 1982||Mar 22, 1984||Loewe Opta Gmbh||Thermal fuse element|
|DE10356788A1 *||Dec 4, 2003||Jul 7, 2005||BSH Bosch und Siemens Hausgeräte GmbH||Sicherungsvorrichtung für eine Heizvorrichtung, Heizvorrichtung und Durchlauferhitzer|
|DE102012025110A1 *||Dec 21, 2012||Jun 26, 2014||Brose Fahrzeugteile Gmbh & Co. Kommanditgesellschaft, Hallstadt||Thermal overload protection structure of electromotor, has spring element that is designed like plate spring, such that spring ends of spring element are pre-mounted and electrically insulated with each other|
|EP0188695A1 *||Nov 21, 1985||Jul 30, 1986||Siemens Aktiengesellschaft||Board carrying a switching arrangement with at least one conductor in the form of a layer|
|EP0352771A2 *||Jul 26, 1989||Jan 31, 1990||Siemens Aktiengesellschaft||Fuse with a spring arm|
|EP0352771A3 *||Jul 26, 1989||Nov 13, 1991||Siemens Aktiengesellschaft||Fuse with a spring arm|
|EP0562438A1 *||Mar 17, 1993||Sep 29, 1993||ROEDERSTEIN SPEZIALFABRIKEN FÜR BAUELEMENTE DER ELEKTRONIK UND KONDENSATOREN DER STARKSTROMTECHNIK GmbH||SDM type thermal protector|
|EP1120888A1 *||Apr 14, 1999||Aug 1, 2001||Zexel Valeo Climate Control Corporation||Brushless motor|
|EP1120888A4 *||Apr 14, 1999||Nov 6, 2002||Zexel Valeo Climate Contr Corp||Brushless motor|
|WO1994003913A1 *||Aug 7, 1992||Feb 17, 1994||Siemens Aktiengesellschaft||Thermal cut-out and process for activating it|
|U.S. Classification||337/404, 337/407|
|Cooperative Classification||H01H2037/763, H01H37/761, H01H2085/466, H01H2037/046|