US3281559A - Thermal fuse having telescopically received contact members - Google Patents
Thermal fuse having telescopically received contact members Download PDFInfo
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- US3281559A US3281559A US369087A US36908764A US3281559A US 3281559 A US3281559 A US 3281559A US 369087 A US369087 A US 369087A US 36908764 A US36908764 A US 36908764A US 3281559 A US3281559 A US 3281559A
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- contact
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- thermal fuse
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H37/00—Thermally-actuated switches
- H01H37/74—Switches in which only the opening movement or only the closing movement of a contact is effected by heating or cooling
- H01H37/76—Contact member actuated by melting of fusible material, actuated due to burning of combustible material or due to explosion of explosive material
- H01H37/764—Contact member actuated by melting of fusible material, actuated due to burning of combustible material or due to explosion of explosive material in which contacts are held closed by a thermal pellet
- H01H37/765—Contact member actuated by melting of fusible material, actuated due to burning of combustible material or due to explosion of explosive material in which contacts are held closed by a thermal pellet using a sliding contact between a metallic cylindrical housing and a central electrode
Definitions
- This invention relates generally to circuit breaking devices, and pertains more particularly to a thermal fuse which interrupts or opens an electric circuit when a predetermined ambient temperature is reached.
- one object of the present invention is to provide a thermal fuse that lends itself readily to miniaturization.
- the invention has for another object the provision of a thermal fuse that will be quickly responsive to a rise in temperature, thereby obviating the chances of damage occurring from objectionable time lags or delays.
- Another object of the invention is to provide a thermal fuse that can be easily assembled and which will not require close manufacturing tolerances.
- the invention has for an aim the employment of telescopically received contact members that can be initially engaged Without difliculty when the parts are being put together, yet which will separate easily when the predetermined temperature is reached.
- Another object of the invention is to provide a thermal fuse of the foregoing character requiring only a relatively few parts so that it can be manufactured at a comparatively low cost.
- Yet another object of the invention is to provide a thermal fuse that can be sealed in order that it will be made moisture-proof and also gas-tight, thereby allowing it to be utilized where high humidity is apt to be experienced or in situations where explosive conditions are likely to be encountered.
- FIGURE 1 is a longitudinal sectional view of one form my invention may assume
- FIGURE 2 is a sectional view taken in the direction of line 22 of FIGURE 1 in order to show to better advantage the construction of the movable contact;
- FIGURE 3 is a longitudinal sectional view corresponding to FIGURE 1 but showing a diflerent embodiment
- FIGURE 4 is a longitudinal sectional view of the modified movable contact before it is placed within the casing shown in FIGURE 3, the view being in the direction of line 4-4 of FIGURE 5, and
- FIGURE 5 is an end view taken from the right in FIGURE 4.
- the thermal fuse there exemplifying my invention has been designated generally by the reference numeral 10.
- the fuse comprises a metallic cylindrical casing or shell 12 having a side wall 14, a closed end wall 16 and an inturned flange or lip 18.
- shoulder 20 is formed internally of the casing or shell 12. Interposed between the flange 18 and the shoulder 20 is a metallic ring or rim 22 that is held captive between the flange and shoulder.
- the ring 22 is part of a glass seal assembly which additionally includes an annular member 24, such as of glass, ceramic or a suitable plas tic, onto which is shrunk the ring 22.
- the glass or porcelain annular member 24 has extending therethrough an electric terminal or lead 26.
- a suitable sealant or potting compound is applied at 28; this compound can be of the epoxy resin type.
- a second terminal or lead 30 is employed at the closed end of the casing.
- the terminal 30 is soldered, brazed or welded directly to the end wall 16 in the illustrated embodiment, the soldered attachment being designated by the reference numeral 32.
- a fixed pin contact 34 extends axially into the casing 12, being in this instance a continuation of the terminal 26. It will be understood, however, that the pin 34 can be either larger or smaller in diameter than the terminal 26 depending upon design requirements. While the contact 34 is fixedly located within the casing 12 by reason of the fact that the terminal or lead 26 is held tight by the annular member 24, a second contact 36 in the form of an appropriately bent metallic strip coacts with the fixed contact 34, being free to move relative to said contact 34.
- the configuration of the movable contact 36 as shown in FIGURE 2 is of appreciable importance as far as fabricating the fuse 10 is concerned.
- the movable contact 36 includes a reversely bent or U-shaped portion indicated generally by the reference numeral 38 having a semicircular bight 40 and sides 42, the sides 42 being somewhat undulated and bulging in each instance at 44 so as to accommodate therebetween the pin contact 34.
- the bulges at 44 merge into substantially parallel shanks 46 and the shanks 46 are in turn integrally connected to arcua-te arms 48 extending about the interior of the shell 12 toward the bight 40.
- the shanks 46 are separated somewhat from each other due to the fact that the diameter of the pin contact 34 is somewhat greater than the normal or natural diameter existing between 0pposite points on the bulges 44. In this way, a firm frictional engagement is effected between the pin contact 34 and the movable contact 36. Stated somewhat differently, the movable contact 36 has its reversely bent portion 38 in what can be considered to be an encircling relationship with the pin contact 34. While good fractional engagement is derived by reason of the particular configuration of the contact 36, nonetheless facile separation can be achieved in a manner presently to be described. Also, it will be appreciated that the arcuate arms 48, through the agency of their inherent resiliency, frictionally bear on the interior of the shell 12. Inasmuch as the strip 36 functions as an electrical contact, it follows that it should be of metal having good electrical conductivity, as well as good resiliency, a berylliumcopper alloy being a satisfactory material, although other metals may be utilized.
- the bushing 5'0 has a bore 52 which is slightly greater in diameter than the diameter of the pin contact 34, thereby allowing the bushing to move freely along the pin contact when required to do so as will hereinafter be explained.
- the bushing 50 has a flange 54 thereon which is formed with a diameter only slightly less than that of the interior of the casing 12.
- the relative diameters of the bore 52 and the flange 54 are such that the left end of the bushing as shown in FIGURE 1 will bear or press against the reversely bent portion 38 and also the arcuate arms 48 of the movable contact 36, thereby avoiding any tendency for the contact to bind or cock within the casing 12.
- a coil spring 56 is positioned between the annular member 24 and the flange 54 belonging to the bushing 50.
- the coil spring by reason of its compressed state, continually acts in a direction against the movable contact 36, doing so through the medium of the bushing 50, so as always to tend to separate the contact 36 from the contact 34.
- a washer 58 is placed next to the movable contact 36 and transmits the force of the coil spring 56 against a temperature sensitive pellet or element 60.
- the precise composition of the temperature sensitive pellet 60 will depend upon the temperature at which the contacts 36, 34 are to separate. In other words, the pellet 60 will normally resist or prevent any such separation but when it becomes sufficiently soft or molten due to heat being transmitted through the casing 12 thereinto, it will allow the spring 56 to disengage the contact 36 from the contact 34.
- Various temperature sensitive pellets are currently available, and the specific pellet 60 would be selected in accordance with the particular temperature at which it should soften in order to safeguard the equipment it is intended to protect.
- the contact pin 34 need not be of any precise length. This is so by virtue of the telescoping engagement thereof with the movable contact 36. If the left end of the 'pin contact 34 resides farther to the right than it appears in FIGURE 1, it will not make any difference because there will still be an adequate engagement between the pin and the reversely bent portion '38 of the contact 36. In other words, the pin contact 34 may vary in length almost as much as the width of the strip constituting the movable contact 36. It will also be observed that only one coil spring 56 isutilized in a construction such as that which has been described. Consequently, only a few parts are required in order to provide a thermal fuse constructed in accordance with the teachings of this invention.
- FIGURES 3-5 a second embodiment of the invention has there been illustrated, being differentiated from the first embodiment by adding the suffix a to the reference numeral 10.
- the embodiment it of FIGUREl is regarded to be superior to the modified arrangement 10a because of the simplicity with which the contact 36 can be fabricated.
- the movable contact of the thermal fuse 1011 such contact having been denoted by the reference numeral 36a, includes an inner tubular portion 62 having a plurality of spring fingers 64 which frictionally bear against the pin contact 34. These fingers 64 can be readily provided by merely slitting what was originally a true tubular portion, the slits having been indicated by the reference numeral 66.
- the movable contact 36a also comprises an outer tubular portion 68 having a plurality of spring fingers 70 formed by means of slits '72.
- the concentric tubular portions 62 and 68 are joined by means of an annular base '74.
- a somewhat longer coil spring 56a should be employed than the spring 56 in order to exert the proper displacement force against the base 74 of the contact 36a.
- the manner of assembling the thermal fuse denoted as 10a is identical with the procedure utilized in assembling the unit 10. Also, the operation is generally similar because the pellet or element 60 becomes sufficiently soft, the coil spring 5601 is instrumental in urging the movable contact 36a in a direction to cause separation thereof with respect to the pin contact 34. Normally, however, the spring fingers 64 produce a good frictional engagement with the pin contact 34 and likewise the spring fingers 70 provide a good frictional engagement with the shell 12. To accomplish this, the fingers 64 have their free ends bent slightly inwardly and the fingers 70 have their free ends bent slightly outwardly. The degree of convergence and divergence is so small as not to be noticeable in FIGURE 4.
- a circuit normally exists between the terminals 26, 30.
- the electrical path is through the terminal 26, the pin contact 34 which is integral therewith, the movable contact 36 (or 36a) and the casing 12 which has attached thereto the other terminal 30.
- the circuit is interrupted or opened to efiect the desired control made necessary due to the excessively high temperature.
- a thermal fuse comprising:
- a thermal fuse comprising:
- a unitary movable electrical contact including a pair of arcuate arms having a radius of curvature corresponding generally to that of said casing so as to bear frictionally thereagainst and a reversely bent portion integral with said arms and extending generally diametrically across the interior of said casing;
- a thermal fuse comprising:
- said strip contact having a generally U-shaped centr-al portion having its sides resiliently engaging said pin contact and having arcuate arms resiliently engaging the interior of said casing;
- a temperature sensitive element normally blocking movement of said strip contact until said temperature sensitive element has melted sufiiciently to allow said strip contact to be moved under the influence of said spring.
- a terminal fuse in accordance with claim 3 includ- (a) a first terminal connected to said fixed pin contact,
- a thermal fuse comprising:
- a thermal fuse comprising:
Description
Oct. 25, 1966 G. F. EBENSTEINER 3,281,559
THERMAL FUSE HAVING TELESCOPICALLY RECEIVED CONTACT MEMBERS Filed May 21, 1964 United States Patent THERMAL FUSE HAVING TELESCOPICALLY RECEIVED CONTACT MEMBERS Gerald F. Ebensteiner, Minneapolis, Minn., assignor, by
mesne assignments, to United-Carr Incorporated, Boston, Mass., a corporation of Delaware Filed May 21, 1964, Ser. No. 369,087
6 Claims. (Cl. 200-142) This invention relates generally to circuit breaking devices, and pertains more particularly to a thermal fuse which interrupts or opens an electric circuit when a predetermined ambient temperature is reached.
There are a number of situations in which it is necessary or at least desirable that a circuit he opened when an excessive or abnormal temperature is experienced. This is for the purpose of protecting temperature-vulnerable equipment from damage in the region where the protective device is installed.
It will be apparent that some uses for thermal devices of the envisaged type require that a miniaturized thermal fuse be employed because space simply does not exist for a thermal fuse of any appreciable size. Accordingly, one object of the present invention is to provide a thermal fuse that lends itself readily to miniaturization.
The invention has for another object the provision of a thermal fuse that will be quickly responsive to a rise in temperature, thereby obviating the chances of damage occurring from objectionable time lags or delays.
Another object of the invention is to provide a thermal fuse that can be easily assembled and which will not require close manufacturing tolerances. In this regard, the invention has for an aim the employment of telescopically received contact members that can be initially engaged Without difliculty when the parts are being put together, yet which will separate easily when the predetermined temperature is reached.
Another object of the invention is to provide a thermal fuse of the foregoing character requiring only a relatively few parts so that it can be manufactured at a comparatively low cost.
Yet another object of the invention is to provide a thermal fuse that can be sealed in order that it will be made moisture-proof and also gas-tight, thereby allowing it to be utilized where high humidity is apt to be experienced or in situations where explosive conditions are likely to be encountered.
These and other objects and advantages of my invention will more fully appear from the following desorption, made in connection with the accompanying drawing, wherein like reference characters refer to the same or similar parts throughout the several views and in which:
FIGURE 1 is a longitudinal sectional view of one form my invention may assume;
FIGURE 2 is a sectional view taken in the direction of line 22 of FIGURE 1 in order to show to better advantage the construction of the movable contact;
FIGURE 3 is a longitudinal sectional view corresponding to FIGURE 1 but showing a diflerent embodiment;
FIGURE 4 is a longitudinal sectional view of the modified movable contact before it is placed within the casing shown in FIGURE 3, the view being in the direction of line 4-4 of FIGURE 5, and
FIGURE 5 is an end view taken from the right in FIGURE 4.
Referring now in detail to the embodiment depicted in FIGURES 1 and 2, the thermal fuse there exemplifying my invention has been designated generally by the reference numeral 10. The fuse comprises a metallic cylindrical casing or shell 12 having a side wall 14, a closed end wall 16 and an inturned flange or lip 18. A
Whereas the electric terminal or lead 26 is located at one end of the casing 12, a second terminal or lead 30 is employed at the closed end of the casing. The terminal 30 is soldered, brazed or welded directly to the end wall 16 in the illustrated embodiment, the soldered attachment being designated by the reference numeral 32.
A fixed pin contact 34 extends axially into the casing 12, being in this instance a continuation of the terminal 26. It will be understood, however, that the pin 34 can be either larger or smaller in diameter than the terminal 26 depending upon design requirements. While the contact 34 is fixedly located within the casing 12 by reason of the fact that the terminal or lead 26 is held tight by the annular member 24, a second contact 36 in the form of an appropriately bent metallic strip coacts with the fixed contact 34, being free to move relative to said contact 34. The configuration of the movable contact 36 as shown in FIGURE 2 is of appreciable importance as far as fabricating the fuse 10 is concerned. From FIGURE 2, it will be discerned that the movable contact 36 includes a reversely bent or U-shaped portion indicated generally by the reference numeral 38 having a semicircular bight 40 and sides 42, the sides 42 being somewhat undulated and bulging in each instance at 44 so as to accommodate therebetween the pin contact 34. The bulges at 44 merge into substantially parallel shanks 46 and the shanks 46 are in turn integrally connected to arcua-te arms 48 extending about the interior of the shell 12 toward the bight 40.
As further shown in FIGURE 2, the shanks 46 are separated somewhat from each other due to the fact that the diameter of the pin contact 34 is somewhat greater than the normal or natural diameter existing between 0pposite points on the bulges 44. In this way, a firm frictional engagement is effected between the pin contact 34 and the movable contact 36. Stated somewhat differently, the movable contact 36 has its reversely bent portion 38 in what can be considered to be an encircling relationship with the pin contact 34. While good fractional engagement is derived by reason of the particular configuration of the contact 36, nonetheless facile separation can be achieved in a manner presently to be described. Also, it will be appreciated that the arcuate arms 48, through the agency of their inherent resiliency, frictionally bear on the interior of the shell 12. Inasmuch as the strip 36 functions as an electrical contact, it follows that it should be of metal having good electrical conductivity, as well as good resiliency, a berylliumcopper alloy being a satisfactory material, although other metals may be utilized.
Attention is now directed to the presence of a bushing 50 of electrically insulating material. The bushing 5'0 has a bore 52 which is slightly greater in diameter than the diameter of the pin contact 34, thereby allowing the bushing to move freely along the pin contact when required to do so as will hereinafter be explained. The bushing 50 has a flange 54 thereon which is formed with a diameter only slightly less than that of the interior of the casing 12. Thus, whereas the bushing is free to move along the pin contact 34, it is also free to move relative to the casing 12. Still further, the relative diameters of the bore 52 and the flange 54 are such that the left end of the bushing as shown in FIGURE 1 will bear or press against the reversely bent portion 38 and also the arcuate arms 48 of the movable contact 36, thereby avoiding any tendency for the contact to bind or cock within the casing 12.
In order to bias or urge the movable contact 36 to the left, which is in a direction to cause separation of its reversely bent portion 38 from its encircling engagement with the pin contact 34, a coil spring 56 is positioned between the annular member 24 and the flange 54 belonging to the bushing 50. Thus, the coil spring, by reason of its compressed state, continually acts in a direction against the movable contact 36, doing so through the medium of the bushing 50, so as always to tend to separate the contact 36 from the contact 34.
A washer 58 is placed next to the movable contact 36 and transmits the force of the coil spring 56 against a temperature sensitive pellet or element 60. The precise composition of the temperature sensitive pellet 60 will depend upon the temperature at which the contacts 36, 34 are to separate. In other words, the pellet 60 will normally resist or prevent any such separation but when it becomes sufficiently soft or molten due to heat being transmitted through the casing 12 thereinto, it will allow the spring 56 to disengage the contact 36 from the contact 34. Various temperature sensitive pellets are currently available, and the specific pellet 60 would be selected in accordance with the particular temperature at which it should soften in order to safeguard the equipment it is intended to protect.
It will be apparent that my thermal fuse can be easily assembled. the inturned flange 18 thereon. This permits the inser tion of the pellet 60 followed by the placement of the washer 58 thereagainst. The contact 36 can then be inserted and the bushing 50 can be placed directly against the contact 36 as shown or a washer similar to the washer 58 can be added. By then introducing the spring 56, all that remains to be added is the assembly or unit comprised ofthe ring 22, the annular member 24 and the terminal 26 which has integral therewith in the illustrated instance the pin contact 34. This assembly is pressed against the coil spring 56 with sufficient force to cause it to be compressed sufficiently so that the right end of the casing 12 can be rolled or formed into the flange 18. With the ring 22 abutting against the shoulder 20, it will be recognized and appreciated that a firm retention of the ring 22 is realized by means of the inturned flange 18. In this way, the pin contact 34 is fixedly anchored and projects axially inwardly relative to the casing 12. The compound 28 can be applied as an added sealing precaution.
It should be particularly noted that the contact pin 34 need not be of any precise length. This is so by virtue of the telescoping engagement thereof with the movable contact 36. If the left end of the 'pin contact 34 resides farther to the right than it appears in FIGURE 1, it will not make any difference because there will still be an adequate engagement between the pin and the reversely bent portion '38 of the contact 36. In other words, the pin contact 34 may vary in length almost as much as the width of the strip constituting the movable contact 36. It will also be observed that only one coil spring 56 isutilized in a construction such as that which has been described. Consequently, only a few parts are required in order to provide a thermal fuse constructed in accordance with the teachings of this invention.
The operation of my thermal fuse should be obvious from what has been set forth. With the parts assembled as shown in FIGURE 1, when the fuse 10 is subjected to a sufficiently high ambient temperature, the pellet or element 60 begins to melt and it quickly changes from its solid state to a semi-liquid state. This allows the com- Initially, the casing 12 does not have.
pressed spring 56 to move the contact 36 to the left. Any displacement of the material constituting the element 60 can move through the central opening in the washer 58 and is then free to pass through the opening in the reversely bent portion 38 formed by the semicircular bight 40 into the void provided by the configuration of the contact 36. Consequently, there is no blocking of the molten material after the pellet 60 has become soft due to sufiicient heat being conducted thereinto. Therefore, because of the construction that has been described, it is not necessary to use a pellet or element 60 that will vaporize, instead it being only necessary to employ a pellet of the type that will become soft and flowable due to sufficient heat.
Directing attention now to FIGURES 3-5, a second embodiment of the invention has there been illustrated, being differentiated from the first embodiment by adding the suffix a to the reference numeral 10. Actually, the embodiment it of FIGUREl is regarded to be superior to the modified arrangement 10a because of the simplicity with which the contact 36 can be fabricated. The movable contact of the thermal fuse 1011, such contact having been denoted by the reference numeral 36a, includes an inner tubular portion 62 having a plurality of spring fingers 64 which frictionally bear against the pin contact 34. These fingers 64 can be readily provided by merely slitting what was originally a true tubular portion, the slits having been indicated by the reference numeral 66. The movable contact 36a also comprises an outer tubular portion 68 having a plurality of spring fingers 70 formed by means of slits '72. The concentric tubular portions 62 and 68 are joined by means of an annular base '74. Owing to the different configuration of the contact 36a from the contact 36, a somewhat longer coil spring 56a should be employed than the spring 56 in order to exert the proper displacement force against the base 74 of the contact 36a.
The manner of assembling the thermal fuse denoted as 10a is identical with the procedure utilized in assembling the unit 10. Also, the operation is generally similar because the pellet or element 60 becomes sufficiently soft, the coil spring 5601 is instrumental in urging the movable contact 36a in a direction to cause separation thereof with respect to the pin contact 34. Normally, however, the spring fingers 64 produce a good frictional engagement with the pin contact 34 and likewise the spring fingers 70 provide a good frictional engagement with the shell 12. To accomplish this, the fingers 64 have their free ends bent slightly inwardly and the fingers 70 have their free ends bent slightly outwardly. The degree of convergence and divergence is so small as not to be noticeable in FIGURE 4.
In both embodiments, a circuit normally exists between the terminals 26, 30. The electrical path is through the terminal 26, the pin contact 34 which is integral therewith, the movable contact 36 (or 36a) and the casing 12 which has attached thereto the other terminal 30. However, when the two contacts 34, 36 (or 34, 36a) are separated, then the circuit is interrupted or opened to efiect the desired control made necessary due to the excessively high temperature.
It will, of course, be understood that various changes may be made in the form, details, arrangements and proportions of the parts without departing from the scope of my invention as set forth in the appended claims.
What is claimed:
1. A thermal fuse comprising:
(a) a cylindricalcasing;
(b) a pair of electric terminals projecting in opposite directions from the ends of said casing;
(c) a pin contact extending axially inwardly from one of said terminals;
(d) a unitary movable contact having a reversely bent portion frictionally engaging the opposite sides of said pin contact and an arcuate arm integral with each end of said reversely bent portion, said arms bearing frictionally against the inside of said cylindrical casing;
(e) a coil spring acting against said movable contact to bias said movable contact in an axial direction to separate said reversely bent portion from said pin contact, and
(f) a temperature sensitive element normally preventing separation of said reversely bent portion from said pin contact until said temperature sensitive element has become softened by sufficient heat.
2. A thermal fuse comprising:
(a) a cylindrical casing;
(b) a unitary movable electrical contact including a pair of arcuate arms having a radius of curvature corresponding generally to that of said casing so as to bear frictionally thereagainst and a reversely bent portion integral with said arms and extending generally diametrically across the interior of said casing;
(c) a fixed pin contact normally projecting axially into frictional engagement with said reversely bent portion to establish an electrical path therebetween;
(d) a coil spring acting upon said movable contact to cause separation thereof from said fixed contact, and
(e) a temperature sensitive element normally resisting movement of said movable contact until said temperture sensitive element has been softened by heat.
3. A thermal fuse comprising:
(a) a cylindrical casing;
(b) a fixed pin contact;
(c) a movable strip contact,
((1) said strip contact having a generally U-shaped centr-al portion having its sides resiliently engaging said pin contact and having arcuate arms resiliently engaging the interior of said casing;
(e) a bushing member encircling said pin contact provided with an inner diameter of a size so as to cause it to bear against said U-shaped portion and an outer diameter so as to cause it to bear against said arcuate arms;
(f) a coil spring engaging said bushing member so as to urge said bushing member axially within said casing to cause said strip contact to also move axially to an extent necessary to separate said U-shaped portion from said pin contact, and
(g) a temperature sensitive element normally blocking movement of said strip contact until said temperature sensitive element has melted sufiiciently to allow said strip contact to be moved under the influence of said spring.
4. A terminal fuse in accordance with claim 3 includ- (a) a first terminal connected to said fixed pin contact,
and
(b) a second terminal connected to said casing,
(c) in which said casing is electrically conductive and said bushing member is non-conductive whereby an electrical path is established through said pin contact, said strip contact and said casing until said temperature sensitive element has become sufficiently molten.
5. A thermal fuse comprising:
(a) a cylindrical casing;
(b) a pair of electric terminals projecting in opposite directions from the ends of said casing;
(c) a pin contact extending axially inwardly from one of said terminals;
(d) a movable contact having concentric inner and outer tubular portions and a connecting portion therebetween,
(e) said inner tubular portion having a plurality of spring fingers frictionally engaging said pin contact and said outer tubular portion having a plurality of of spring fingers frictionally engaging the interior of said casing;
(f) a coil spring acting against said connecting portion to bias said movable contact in an axial direction to separate said inner tubular portion from said pin contact, and
(g) a temperature sensitive element normally preventing separation of said inner tubular portion from said pin contact until said temperature sensitive element has become softened by sufficient heat.
6. A thermal fuse comprising:
(a) a cylindrical casing;
(b) a fixed pin contact projecting into said casing from one end;
(c) a movable contact cooperable with said fixed contact having a first portion thereof resiliently and frictionally engaging the interior of said casing and a second portion thereof resiliently and frictionally engaging only the sides of said fixed contact;
(d) spring means urging said movable contact in a direction to cause disengagement of said movable contact from said fixed contact, and
(e) a temperature sensitive pellet adjacent the other end of said casing for resisting movement of said movable contact until said pellet has become softened by suflicient heat.
References Cited by the Examiner UNITED STATES PATENTS 1,691,705 11/ 1928 Cook 200-123 2,037,544 4/1936 Seaman 200-166 2,180,711 11/ 1939 Lehmann 200-142 X 2,750,469 6/1956 Baker 200-114 X 2,810,893 10/1957 Nijland 200-166 X 2,934,628 4/1960 Massar et al. 200-117 X 2,955,179 10/1960 Milton et al. 200-142 2,968,787 1/1961 Wooton 339-213 3,169,817 2/1965 McKee 339-256 3,180,958 4/1965 Merrill 200-142 BERNARD A. GILHEANY, Primary Examiner. H. B. GILSON, Assistant Examiner.
Claims (1)
- 2. A THERMAL FUSE COMPRISING: (A) A CYLINDRICAL CASING; (B) A UNITARY MOVABLE ELECTRICAL CONTACT INCLUDING A PAIR OF ARCUATE ARMS HAVING A RADIUS OF CURVATURE CORRESPONDING GENERALLY TO THAT OF SAID CASING SO AS TO BEAR FRICTIONALLY THEREAGAINST AND A REVERSELY BENT PORTION INTEGRAL WITH SAID ARMS AND EXTENDING GENERALLY DIAMETRICALLY ACROSS THE INTERIOR OF SAID CASING; (C) A FIXED PIN CONTACT NORMALLY PROJECTING AXIALLY INTO FRICTIONAL ENGAGEMENT WITH SAID REVERSELY BENT PORTION TO ESTABLISH AN ELECTRICAL PATH THEREBETWEEN; (D) A COIL SPRING ACTING UPON SAID MOVABLE CONTACT TO CAUSE SEPARATION THEREOF FROM SAID FIXED CONTACT, AND (E) A TEMPERATURE SENSITIVE ELEMENT NORMALLY RESISTING MOVEMENT OF SAID MOVABLE CONTACT UNTIL SAID TEMPERTURE SENSITIVE ELEMENT HAS BEEN SOFTENED BY HEAT.
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US369087A US3281559A (en) | 1964-05-21 | 1964-05-21 | Thermal fuse having telescopically received contact members |
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US369087A US3281559A (en) | 1964-05-21 | 1964-05-21 | Thermal fuse having telescopically received contact members |
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US3281559A true US3281559A (en) | 1966-10-25 |
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US369087A Expired - Lifetime US3281559A (en) | 1964-05-21 | 1964-05-21 | Thermal fuse having telescopically received contact members |
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Cited By (19)
Publication number | Priority date | Publication date | Assignee | Title |
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US3519972A (en) * | 1969-03-18 | 1970-07-07 | Micro Devices Corp | Temperature responsive electric switch |
US3599137A (en) * | 1968-07-05 | 1971-08-10 | Mitsubishi Electric Corp | Current limiting device |
US3670282A (en) * | 1968-08-07 | 1972-06-13 | Mitsubishi Electric Corp | Current limiting device |
DE2716579A1 (en) * | 1976-04-15 | 1977-10-20 | Matsushita Electric Ind Co Ltd | TEMPERATURE DEPENDENT CURRENT BREAKER |
US20050088272A1 (en) * | 2003-10-28 | 2005-04-28 | Nec Schott Components Corporation | Thermal pellet incorporated thermal fuse and method of producing thermal pellet |
US20050179516A1 (en) * | 2002-04-24 | 2005-08-18 | Tokihiro Yoshikawa | Temperature sensing material type thermal use |
US20060208845A1 (en) * | 2005-03-17 | 2006-09-21 | Nec Schott Components Corporation | Thermal fuse employing thermosensitive pellet |
US20060232372A1 (en) * | 2005-04-18 | 2006-10-19 | Nec Schott Components Corporation | Thermal fuse employing thermosensitive pellet |
US20070236324A1 (en) * | 2004-09-17 | 2007-10-11 | Tokihiro Yoshikawa | Thermal pellet type thermal fuse |
US20090091417A1 (en) * | 2007-10-05 | 2009-04-09 | Nec Schott Components Corporation | Thermal fuse employing thermosensitive pellet |
US20100033295A1 (en) * | 2008-08-05 | 2010-02-11 | Therm-O-Disc, Incorporated | High temperature thermal cutoff device |
US20100219929A1 (en) * | 2007-10-15 | 2010-09-02 | Lee Jong-Ho | Thermal fuse with current fuse function |
US20110285497A1 (en) * | 2010-05-18 | 2011-11-24 | Chun-Chang Yen | Thermal fuse |
US20120182116A1 (en) * | 2009-07-15 | 2012-07-19 | Vishay Resistors Belgium Bvba | Thermal switch |
US20120255162A1 (en) * | 2009-11-30 | 2012-10-11 | The Hosho Corporation | Temperature-sensitive pellet type thermal fuse |
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US9171654B2 (en) | 2012-06-15 | 2015-10-27 | Therm-O-Disc, Incorporated | High thermal stability pellet compositions for thermal cutoff devices and methods for making and use thereof |
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US3599137A (en) * | 1968-07-05 | 1971-08-10 | Mitsubishi Electric Corp | Current limiting device |
US3670282A (en) * | 1968-08-07 | 1972-06-13 | Mitsubishi Electric Corp | Current limiting device |
US3519972A (en) * | 1969-03-18 | 1970-07-07 | Micro Devices Corp | Temperature responsive electric switch |
DE2716579A1 (en) * | 1976-04-15 | 1977-10-20 | Matsushita Electric Ind Co Ltd | TEMPERATURE DEPENDENT CURRENT BREAKER |
US4126845A (en) * | 1976-04-15 | 1978-11-21 | Matsushita Electric Industrial Co., Ltd. | Temperature responsive current interrupter |
US20050179516A1 (en) * | 2002-04-24 | 2005-08-18 | Tokihiro Yoshikawa | Temperature sensing material type thermal use |
US7323965B2 (en) | 2002-04-24 | 2008-01-29 | Nec Schott Components Corporation | Thermal fuse using thermosensitive material |
US7323966B2 (en) | 2003-10-28 | 2008-01-29 | Nec Schott Components Corporation | Thermal pellet incorporated thermal fuse and method of producing thermal pellet |
US20050088272A1 (en) * | 2003-10-28 | 2005-04-28 | Nec Schott Components Corporation | Thermal pellet incorporated thermal fuse and method of producing thermal pellet |
US20070236324A1 (en) * | 2004-09-17 | 2007-10-11 | Tokihiro Yoshikawa | Thermal pellet type thermal fuse |
US7362208B2 (en) | 2004-09-17 | 2008-04-22 | Nec Schott Components Corporation | Thermal pellet type thermal fuse |
US20060208845A1 (en) * | 2005-03-17 | 2006-09-21 | Nec Schott Components Corporation | Thermal fuse employing thermosensitive pellet |
US7330098B2 (en) * | 2005-03-17 | 2008-02-12 | Nec Schott Components Corporation | Thermal fuse employing a thermosensitive pellet |
US20090179729A1 (en) * | 2005-04-18 | 2009-07-16 | Nec Schott Components Corporation | Thermal fuse employing thermosensitive pellet |
US20060232372A1 (en) * | 2005-04-18 | 2006-10-19 | Nec Schott Components Corporation | Thermal fuse employing thermosensitive pellet |
US20090091417A1 (en) * | 2007-10-05 | 2009-04-09 | Nec Schott Components Corporation | Thermal fuse employing thermosensitive pellet |
US7843307B2 (en) | 2007-10-05 | 2010-11-30 | Nec Schott Components Corporation | Thermal fuse employing thermosensitive pellet |
US20100219929A1 (en) * | 2007-10-15 | 2010-09-02 | Lee Jong-Ho | Thermal fuse with current fuse function |
US20100033295A1 (en) * | 2008-08-05 | 2010-02-11 | Therm-O-Disc, Incorporated | High temperature thermal cutoff device |
US9779901B2 (en) | 2008-08-05 | 2017-10-03 | Therm-O-Disc, Incorporated | High temperature material compositions for high temperature thermal cutoff devices |
US8961832B2 (en) | 2008-08-05 | 2015-02-24 | Therm-O-Disc, Incorporated | High temperature material compositions for high temperature thermal cutoff devices |
US9058949B2 (en) * | 2009-07-15 | 2015-06-16 | Vishay Resistors Belgium Bvba | Thermal switch |
US20120182116A1 (en) * | 2009-07-15 | 2012-07-19 | Vishay Resistors Belgium Bvba | Thermal switch |
US20120255162A1 (en) * | 2009-11-30 | 2012-10-11 | The Hosho Corporation | Temperature-sensitive pellet type thermal fuse |
US20110285497A1 (en) * | 2010-05-18 | 2011-11-24 | Chun-Chang Yen | Thermal fuse |
US20130057382A1 (en) * | 2010-05-18 | 2013-03-07 | Chun-Chang Yen | Thermal fuse |
US9171654B2 (en) | 2012-06-15 | 2015-10-27 | Therm-O-Disc, Incorporated | High thermal stability pellet compositions for thermal cutoff devices and methods for making and use thereof |
US20150091689A1 (en) * | 2013-10-02 | 2015-04-02 | Therm-O-Disc, Incorporated | Thermal cut-off device |
US9378910B2 (en) * | 2013-10-02 | 2016-06-28 | Therm-O-Disc, Incorporated | Thermal cut-off device |
US20160042904A1 (en) * | 2014-08-08 | 2016-02-11 | Tyco Electronics France Sas | Smart Fuse for Circuit Protection |
US9548177B2 (en) * | 2014-08-08 | 2017-01-17 | Littelfuse France Sas | Smart fuse for circuit protection |
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