Abstract
Problem To maintain a low internal resistance value and adjust spring characteristics by using a movable contact made of a multilayered material.
Means for Solving Problem A thermosensitive pellet-type thermal fuse includes, in an interior of a cylindrical case having electrical conductivity, a thermosensitive pellet that melts or softens at a temperature, a strong compression spring configured to press the thermosensitive pellet, an insulating cover closing the cylindrical case, a weak compression spring abutting against the insulating cover, a first lead extending through the insulating cover and including an inner end as a fixed contact, a movable contact electrically connecting to the first lead and the cylindrical case, a sealing resin provided surrounding a portion of the first lead and covering an outer end portion of the insulating cover, and sealing an open end portion of the cylindrical case, and a second lead disposed at one end of the cylindrical case. The movable contact includes a conductive base material and a conductive member covering a predetermined surface of the conductive base material. The conductive member is provided to contact portions with the fixed contact and an inner wall surface of the cylindrical case, and is made of a material having a Young’s modulus and a rigidity different from those of the conductive base material.
Claims
1. A contact material for a thermal fuse, the contact material comprising: a conductive base material; and a conductive member provided covering a predetermined area of a surface of the conductive base material, wherein the conductive member is provided to at least contact portions with a fixed contact and a cylindrical case of the thermal fuse, and is made of a material having a Young’s modulus and a rigidity different from a Young’s modulus and a rigidity of the conductive base material.
2. The contact material for a thermal fuse according to claim 1, wherein the conductive member is provided by an overlay or an inlay to the contact portions.
3. The contact material for a thermal fuse according to claim 1, wherein the conductive base material is Cu or a Cu alloy.
4. The contact material for a thermal fuse according to claim 1, wherein the conductive member is Ag or a Ag alloy.
5. The contact material for a thermal fuse according to claim 4, wherein the Ag alloy is selected from any one of AgCuO, AgSnO2, AgSnO2—In2O3, or AgNi.
6. The contact material for a thermal fuse according to claim 1, wherein a metal interface layer composed of any one of a Ag plating layer, a Ni plating layer, a Ni—P alloy plating layer, and an alloy plating layer with Ni as a main component is provided at an interface between the conductive base material and the conductive member.
7. The contact material for a thermal fuse according to claim 1, wherein the conductive base material is made of a material that has a greater spring force, compresses more readily, has more favorable compression returnability, and has a higher Young’s modulus and a higher rigidity than the conductive member.
8. The contact material for a thermal fuse according to claim 1, wherein the conductive member is made of a material having a lower Young’s modulus and a lower rigidity than the conductive base material.
9. The contact material for a thermal fuse according claim 8, wherein the conductive member is made of a material further having a lower electrical resistance than the conductive base material.
10. A movable contact comprising: a conductive base material; and a conductive member provided covering a predetermined area of a surface of the conductive base material, wherein the conductive member is provided to at least contact portions with a fixed contact and a cylindrical case of a thermal fuse, and is made of a material having a Young’s modulus and a rigidity different from a Young’s modulus and a rigidity of the conductive base material.
11. The movable contact according to claim 10, wherein the conductive member is provided by an overlay or an inlay to the contact portions.
12. The movable contact according to claim 10, wherein the conductive base material is Cu or a Cu alloy.
13. The movable contact according to claim 10, wherein the conductive member is Ag or a Ag alloy.
14. The movable contact according to claim 13, wherein the Ag alloy is selected from any one of AgCuO, AgSnO2, AgSnO2—In2O3, or AgNi.
15. The movable contact according to claim 10, wherein a metal interface layer composed of any one of a Ag plating layer, a Ni plating layer, a Ni—P alloy plating layer, and an alloy plating layer with Ni as a main component is provided at an interface between the conductive base material and the conductive member.
16. The movable contact according to claim 10, wherein the conductive base material is made of a material that has a greater spring force, compresses more readily, has more favorable compression returnability, and has a higher Young’s modulus and a higher rigidity than the conductive member.
17. The movable contact according to claim 10, wherein the conductive member is made of a material having a lower Young’s modulus and a lower rigidity than the conductive base material.
18. The movable contact according claim 17, wherein the conductive member is made of a material further having a lower electrical resistance than the conductive base material.
19. A thermosensitive pellet-type thermal fuse comprising: in an interior of a cylindrical case having favorable electrical conductivity and favorable thermal conductivity, a thermosensitive pellet that melts or softens at a specific temperature; a strong compression spring configured to press the thermosensitive pellet; an insulating cover closing an opening of the cylindrical case; a weak compression spring abutting against the insulating cover; a first lead extending through the insulating cover and including an inner end as a fixed contact; a movable contact electrically connecting to the first lead and the cylindrical case; a sealing resin provided surrounding a portion of the first lead and covering an outer end portion of the insulating cover, and sealing an open end portion of the cylindrical case; and a second lead disposed at one end of the cylindrical case, wherein the movable contact includes a conductive base material and a conductive member covering a predetermined surface of the conductive base material, and the conductive member is provided to at least contact portions with the fixed contact and an inner wall surface of the cylindrical case, and is made of a material having a Young’s modulus and a rigidity different from a Young’s modulus and a rigidity of the conductive base material.
20. The thermosensitive pellet-type thermal fuse according to claim 19, wherein the conductive member is provided by an overlay or an inlay to the contact portions.
21. The thermosensitive pellet-type thermal fuse according to claim 19, wherein the conductive base material is Cu or a Cu alloy.
22. The thermosensitive pellet-type thermal fuse according to claim 19, wherein the conductive member is Ag or a Ag alloy.
23. The thermosensitive pellet-type thermal fuse according to claim 22, wherein the Ag alloy is selected from any one of AgCuO, AgSnO2, AgSnO2—In2O3, or AgNi.
24. The thermosensitive pellet-type thermal fuse according to claim 19, wherein a metal interface layer composed of any one of a Ag plating layer, a Ni plating layer, a Ni—P alloy plating layer, and an alloy plating layer with Ni as a main component is provided at an interface between the conductive base material and the conductive member.
25. The thermosensitive pellet-type thermal fuse according to claim 19, wherein the conductive base material is made of a material that has a greater spring force, compresses more readily, has more favorable compression returnability, and has a higher Young’s modulus and a higher rigidity than the conductive member.
26. The thermosensitive pellet-type thermal fuse according to claim 19, wherein the conductive member is made of a material having a lower Young’s modulus and a lower rigidity than the conductive base material.
27. The thermosensitive pellet-type thermal fuse according claim 26, wherein the conductive member is made of a material further having a lower electrical resistance than the conductive base material.
Description
BRIEF DESCRIPTION OF DRAWINGS
[0012] FIG. 1 is a diagram illustrating a portion of a contact material 10 according to the present invention, FIG. 1(a) being a diagram illustrating an example of a surface on a side of movable contacts that includes a contact portion with a fixed contact, and punching locations of the movable contacts, and FIG. 1(b) being a diagram illustrating an example of a surface of a side of the movable contacts that includes a contact portion with a cylindrical case, and punching locations of the movable contacts.
[0013] FIG. 2 illustrates an example of a shape of a movable contact 20 according to the present invention, FIG. 2(a) being a plan view, FIG. 2(b) being a side view, and FIG. 2(c) being a bottom view.
[0014] FIG. 3 illustrates an example of a cross-sectional view of the movable contact according to the present invention, FIG. 3(a) being a view obtained by leveling, into a flat plate, a cross-section taken along a line D-D in FIG. 2(a), and FIG. 3(b) being a view obtained by leveling, into a flat plate, a cross-section taken along a line d-d in FIG. 2(a).
[0015] FIG. 4 is a cross-sectional view illustrating a thermosensitive pellet-type thermal fuse 40 suitable for applying the movable contact 20 according to the present invention.
[0016] FIG. 5 illustrates an example of a cross-sectional view of a movable contact according to a modified example, FIG. 5(a) being a view obtained by leveling, into a flat plate, a cross-section taken along a line D-D in FIG. 2(a), and FIG. 5(b) being a view obtained by leveling, into a flat plate, a cross-section taken along a line d-d in FIG. 2(a).
[0017] FIG. 6 is a cross-sectional view illustrating operation of the thermosensitive pellet-type thermal fuse according to the present invention, FIG. 6(a) illustrating a cross-sectional view of the thermosensitive pellet-type thermal fuse before operation, and FIG. 6(b) illustrating a cross-sectional view of the thermosensitive pellet-type thermal fuse after operation.
[0018] FIG. 7 is a diagram illustrating a modified example of the punching locations of a movable contacts in the contact material 10 according to the present invention, FIG. 7(a) being a diagram illustrating a modified example of the punching locations on the surface of the side of the movable contacts that includes the contact portion with the fixed contact, and FIG. 7(b) being a diagram illustrating a modified example of the punching locations on the surface of the side of the movable contacts that includes the contact portion with the cylindrical case.
DESCRIPTION OF EMBODIMENTS
[0019] An example of a contact material 10 for a thermal fuse according to the present invention is illustrated in FIG. 1. The contact material 10 for a thermal fuse includes a conductive base material 11 and a conductive member 12 provided in a necessary areas of the conductive base material 11. The conductive member 12 is provided only to desired portions of a thermosensitive pellet-type thermal fuse, including contact portions with a fixed contact and a cylindrical case, and is made of a material having a Young’s modulus and a rigidity different from those of the conductive base material. FIG. 1 is a diagram illustrating an example of a portion of the contact material prior to punching the movable contacts, with a star-shaped portion 13 in FIG. 1 indicating a punching location of a movable contact. The contact material 10 for a thermal fuse is processed into a predetermined shape, and can be applied to a movable contact 47 of a thermosensitive pellet-type thermal fuse 40 illustrated in FIG. 4. For example, the contact material 10 for a thermal fuse according to the present invention is processed into the movable contact 20 or 30 such as illustrated in FIG. 2 or FIG. 3 by press-punching and used. The contact material 10 for a thermal fuse includes the conductive base material 11 that has spring force, compresses readily, has favorable compression returnability, and has a high Young’s modulus and a high rigidity, and the conductive member 12 provided in necessary areas of the conductive base material 11 and having a Young’s modulus and a rigidity lower than those of the conductive base material 11. The conductive member 12 may be provided only to desired portions of the thermosensitive pellet-type thermal fuse, including the contact portions with the fixed contact and the cylindrical case. The conductive member 12 disposed on side (a) of FIG. 1 is a surface including the contact portion with the fixed contact of the thermal fuse, and is an inner side surface 22a of a recessed surface of the movable contact 20 in FIG. 2. On the other hand, the conductive member 12 disposed on side (b) of FIG. 1 is a surface including the contact portion with the cylindrical case of the thermal fuse, and is an outer side surface 22b of the recessed surface of the movable contact 20 in FIG. 2. The contact material 10 for a thermal fuse is formed into the movable contact 20 having a star-shape including extending portions of five points, for example, the extending portions are further bent in one direction in a bowl shape or dish shape, and the fixed contact of the thermal fuse is abutted against a bottom surface of the inner side surface 22a of the bowl shape or the dish shape of the extending portions so that the outer side surface 22b of the extending portions comes into contact with a cylindrical case inner wall of the thermal fuse and can slide against the case inner wall. The conductive member 12 is provided in an overlay extending the conductive member 12 over, or in an inlay fitting the conductive member 12 into, at least the contact portion with the fixed contact of the conductive base material 11 and the contact portion with the cylindrical case. The movable contact of the present invention, by compounding the conductive member with the conductive base material, makes it possible to combine materials having different Young’s moduli and change a thickness of the contact material itself, as necessary. This makes it easy to adjust the spring characteristics of the contact material to a desired range, suppressing a decrease in the spring force of the movable contact material caused by annealing. Note that the overlaid or inlaid surface may not necessarily be formed flush (flat) with the conductive base material surface, and may be configured to be uneven by the overlay portion or the inlay portion. The movable contact 20 is preferably imparted with a recessed star shape as illustrated in FIG. 2. As long as the movable contact 20 can come into contact with and separate from the fixed contact of the desired thermosensitive pellet-type thermal fuse and come into contact with the cylindrical case inner wall and slide against the case inner wall, the movable contact 20 may have any shape and is not limited to the star shape. For example, a star shape with an increased or decreased number of points or a circular dish shape are also possible. Further, the movable contact 20 may, at an interface between a conductive base material 51 and a conductive member 52, be modified to a movable contact 50 provided with a metal interface layer 53 composed of any one of a Ag plating layer, a Ni plating layer, a Ni-P alloy plating layer, and an alloy plating layer with Ni as a main component for prevention of interdiffusion and improvement of adhesion of both materials. This delays or prevents diffusion of the conductive member 12 into the conductive base material 11 in a thermal environment.
[0020] Means for changing the Young’s modulus and the rigidity of the contact material 10 include a method of creating a difference in thickness between the conductive base material 11 and the conductive member 12, a method of creating a difference by changing a degree of work hardening between the materials of the conductive base material 11 and the conductive member 12 by rolling/forging or the like, or by work hardening one of the conductive base material 11 and the conductive member 12, and a method of creating a difference by changing the degree of heat treatment of quenching/annealing or the like between the materials of the conductive base material 11 and conductive member 12 or by applying any of the heat treatments described above to one of the materials of the conductive base material 11 and the conductive member 12. Further, in the case of the conductive member 12 made of an alloy, the Young’s modulus and the rigidity of the contact material 10 may be adjusted by increasing or decreasing the content of a metal component or a metal oxide of the constituent alloy. For example, in the case of a Ag alloy, the Young’s modulus and the rigidity of the contact material 10 may be adjusted by increasing or decreasing the component amount of CuO, Ni, SnO.sub.2, In.sub.2O.sub.3, or the like.
[0021] The thermosensitive pellet-type thermal fuse 40 according to the present invention is a thermosensitive pellet-type thermal fuse that utilizes the contact material 10 for a thermal fuse or the movable contact 20. The thermosensitive pellet-type thermal fuse 40, as illustrated in FIG. 4, includes, in an interior of a cylindrical case 41 having favorable electrical conductivity and favorable thermal conductivity, a thermosensitive pellet 42 that melts or softens at a specific temperature, a strong compression spring 43 configured to press the thermosensitive pellet 42, an insulating cover 44 closing an opening of the cylindrical case 41, a weak compression spring 45 abutting against the insulating cover 44, a first lead 46 extending through the insulating cover 44 and including an inner end as a fixed contact 400, the movable contact 47 electrically connecting to the first lead 46 and the cylindrical case 41, a sealing resin 48 provided surrounding a portion of the first lead 46 and covering an outer end portion of the insulating cover 44, and sealing an open end portion of the cylindrical case 41, and a second lead 49 disposed at one end of the cylindrical case 41. The movable contact 47 includes the conductive base material and the conductive member covering a predetermined surface of the conductive base material, and the conductive member is provided only to desired portions including the contact portions with the fixed contact 400 and the cylindrical case 41, and is made of a material having a Young’s modulus and a rigidity different from those of the conductive base material. The conductive member of the movable contact may be provided to the contact portions of the conductive base material with the fixed contact and the cylindrical case by an overlay extending the conductive member over a planar surface of the conductive base material or an inlay fitting the conductive member into a cavity provided in the conductive base material. The movable contact is constituted by the conductive base material and the conductive member, making it possible to combine materials having different Young’s moduli, and change the thickness of the contact material itself, as necessary. Accordingly, the movable contact of the thermosensitive pellet-type thermal fuse of the present invention facilitates adjustment of the spring characteristics to a desired range and suppresses a reduction in the spring force of the movable contact material caused by annealing. The overlaid or inlaid surface may not necessarily be formed flush (flat) with the conductive base material surface, and may be configured to be uneven by the overlay portion or the inlay portion. For example, although not specifically illustrated in FIG. 4, the movable contact 47 is provided with an overlay layer or an inlay layer composed of a conductive base material 21 having springiness that compresses readily, has favorable compression returnability, and has a high Young’s modulus and a high rigidity, and the conductive members 22a, 22b having Young’s moduli and rigidities lower than those of the conductive base material 21 in the desired portion 22a including the contact portion with the fixed contact 400 and in the contact portion 22b with the cylindrical case 41, as described in FIG. 2. The thermosensitive pellet-type thermal fuse 40 may further be provided with a pressing plate 401 on both ends of the strong compression spring 43 as necessary, and, as necessary, the first lead 46 may be inserted into an insulating porcelain tube 402, and the insulating porcelain tube 402 may be adhered by the sealing resin 48.
EXAMPLES
[0022] The contact material 10 for a thermal fuse of FIG. 1 is illustrated as example 1 of the present invention. The contact material 10 for a thermal fuse is constituted by the conductive base material 11 made of a phosphor bronze selected from Cu or a Cu alloy that has spring force, compresses readily, has favorable compression retumability, and has a high Young’s modulus and a high rigidity (Cu-8Sn-0.2P, Young’s modulus: 110 [E/GPa], shear modulus: 43 [G/GPa], electrical resistance: 2.3 [.Math.Ω•cm]) and the conductive member 12 made of Ag or a Ag alloy having a Young’s modulus and a rigidity lower than those of the conductive base material 11 and an electrical resistance value lower than that of the conductive base material 11 in desired portions of the conductive base material 11 including the contact portions with the fixed contact and the cylindrical case (Young’s modulus: 82.7 [E/GPa], shear modulus: 30.3 [G/GPa], electrical resistance: 1.47 [.Math.Ω•cm]). The conductive member 12 made of a Ag alloy is selected from Ag alloys including any one of oxide metal alloys such as AgCuO, AgSnO.sub.2, and AgSnO.sub.2—In.sub.2O.sub.3 and Ag alloys such as AgNi. The conductive member 12, while not particularly limited to this, may have an electrical resistance value lower than that of the conductive base material 11. The contact material 10 for a thermal fuse is molded into the movable contact 20 or 30 of the thermosensitive pellet-type thermal fuse illustrated in FIG. 2 or FIG. 3, and utilized in the thermosensitive pellet-type thermal fuse. Means for adjusting the Young’s modulus and the rigidity of the contact material 10 for a thermal fuse include a method of creating a difference in thickness between the conductive base material 11 and the conductive member 12, a method of creating a difference by changing a degree of work hardening between the materials of the conductive base material 11 and the conductive member 12 by rolling/forging or the like, or by work hardening one of the conductive base material 11 and the conductive member 12, a method of creating a difference by changing the degree of heat treatment of quenching/annealing or the like between the materials of the conductive base material 11 and the conductive member 12 or by applying any of the heat treatments described above to only one of the materials of the conductive base material 11 and conductive member 12, and a method of increasing or decreasing the content of CuO, Ni, SnO.sub.2, or In.sub.2O.sub.3 in the Ag alloy constituting the conductive member 12.
[0023] The movable contacts 20, 30 of example 2 of the present invention are illustrated in FIG. 2 and FIG. 3. The movable contacts 20, 30 are composed of the conductive base materials 21, 31 made of a Cu or Cu alloy that has a spring force, compresses readily, has favorable compression returnability, and a high Young’s modulus and a high rigidity, and conductive members 22a, 22b and 32 made of Ag or Ag alloys having lower Young’s moduli and rigidities than those of the conductive base materials 21, 31 in desired portions of the conductive base materials 21, 31, including the contact portions with the fixed contact and the cylindrical case. The conductive members 22a, 22b, and 32, while not particularly limited to this, may have electrical resistance values lower than those of the conductive base materials 21, 31.
[0024] Movable contacts 20, 50 of example 3 of the present invention are illustrated in FIG. 2 and FIG. 5. The movable contacts 20, 50 are constituted by the conductive base materials 21, 51 made of a phosphor bronze selected from Cu or a Cu alloy that has spring force, compresses readily, has favorable compression returnability, and has a high Young’s modulus and a high rigidity (Cu-8Sn-0.2P, Young’s modulus: 110 [E/GPa], shear modulus: 43 [G/GPa], electrical resistance: 2.3 [.Math.Ω•cm]) and the conductive members 22a, 22b, and 52 made of silver selected from Ag or a Ag alloy having a Young’s modulus and a rigidity lower than those of the conductive base materials 21, 51 and an electrical resistance value lower than those of the conductive base materials 21, 51 in desired portions of the conductive base materials 21, 51, including the contact portions with the fixed contact and the cylindrical case (Young’s modulus: 82.7 [E/GPa], shear modulus: 30.3 [G/GPa], electrical resistance: 1.47 [.Math.Ω•cm]). Furthermore, as illustrated in FIG. 5, in an interface between the conductive base material 51 and the conductive member 52, the metal interface layer 53 composed of a Ni plating layer for prevention of interdiffusion and improvement of adhesion of both materials is provided. The movable contacts 20, 50 are composed of the conductive base material and the conductive member having Young’s moduli and rigidities different from each other, and the conductive member, while not particularly limited to this, may have an electrical resistance value lower than that of the conductive base material.
[0025] The thermosensitive pellet-type thermal fuse 40 of FIG. 4 is illustrated as example 4 of the present invention. The thermosensitive pellet-type thermal fuse 40 includes, in the interior of the cylindrical case 41 having favorable electrical conductivity and favorable thermal conductivity, the thermosensitive pellet 42 that melts or softens at a specific temperature, the strong compression spring 43 configured to press the thermosensitive pellet 42, the insulating cover 44 closing the opening of the cylindrical case 41, the weak compression spring 45 abutting against the insulating cover 44, the first lead 46 extending through the insulating cover 44 and including the inner end as the fixed contact 400, the movable contact 47 electrically connecting to the first lead 46 and the cylindrical case 41, the sealing resin 48 provided surrounding a portion of the first lead 46 and covering the outer end portion of the insulating cover 44, and sealing the open end portion of the cylindrical case 41, and the second lead 49 disposed at one end of the cylindrical case 41. The movable contact 47 is constituted by the conductive base material made of a phosphor bronze selected from Cu or a Cu alloy that has spring force, compresses readily, has favorable compression returnability, and has a high Young’s modulus and a high rigidity (Cu-8Sn-0.2P, Young’s modulus: 110 [E/GPa], shear modulus: 43 [G/GPa], electrical resistance: 2.3 [.Math.Ω•cm]) and the conductive member selected from Ag or a Ag alloy having a Young’s modulus and a rigidity lower than those of the conductive base material and an electrical resistance value lower than that of the conductive base material, covering only the vicinity of the contact portions of this conductive base material with the fixed contact 400 and the cylindrical case 41 (Young’s modulus: 82.7 [E/GPa], shear modulus: 30.3 [G/GPa], electrical resistance: 1.47 [.Math.Ω•cm]). The conductive member made of a Ag alloy is selected from Ag alloys including any one of oxide metal alloys such as AgCuO, AgSnO.sub.2, and AgSnO.sub.2—In.sub.2O.sub.3 and Ag alloys such as AgNi. The movable contact 47 is composed of the conductive base material and the conductive member having Young’s moduli and rigidities different from each other, and the conductive member, while not particularly limited to this, may have an electrical resistance value lower than that of the conductive base material. Means for adjusting the Young’s modulus and the rigidity of the movable contact 47 include a method of creating a difference in thickness between the conductive base material and the conductive member, a method of creating a difference by changing a degree of work hardening between the materials of the conductive base material and the conductive member by rolling/forging or the like, or by work hardening one of the conductive base material and the conductive member, a method of creating a difference by changing the degree of heat treatment of quenching/annealing or the like between the materials of the conductive base material and the conductive member or by applying any of the heat treatments described above to only one of the materials of the conductive base material and conductive member, and a method of increasing or decreasing the content of CuO, Ni, SnO.sub.2, and In.sub.2O.sub.3 in the Ag alloy constituting the conductive member.
[0026] FIG. 7 is a diagram illustrating a modified example of the punching locations of the movable contacts in the contact material 10 according to the present invention. FIG. 7(a) is a diagram illustrating a modified example of the punching locations on the surface of the side of the movable contacts that includes the contact portion with the fixed contact, and FIG. 7(b) is a diagram illustrating a modified example of the punching locations on the surface of the side of the movable contacts that includes the contact portion with the cylindrical case. In this way, the punching locations 13 of the movable contact in the contact material 10 need only be disposed and formed so that the conductive member 12 of the movable contact at least corresponds to the contact portions with the fixed contact and the cylindrical case of the thermosensitive pellet-type thermal fuse, and thus comes into contact with the fixed contact and the cylindrical case.
INDUSTRIAL APPLICABILITY
[0027] The present invention can be suitably utilized for a temperature protection element including a contact, such as a contact separation-type thermal fuse for high current or a bi-metal-type protection element including a movable contact and configured to separate the contact upon detection of an abnormal temperature, and can be particularly suitably utilized for a thermosensitive pellet-type thermal fuse.
TABLE-US-00001 REFERENCE SIGNS LIST 10 Contact material for thermal fuse 11 Conductive base material 12 Conductive member 13 Punching location of movable contact 20 Movable contact 21 Conductive base material 22a, 22b Conductive member 30 Movable contact 31 Conductive base material 32 Conductive member 40 Thermosensitive pellet-type thermal fuse 41 Cylindrical case 42 Thermosensitive pellet 43 Strong compression spring 44 Insulating cover 45 Weak compression spring 46 First lead 47 Movable contact 48 Sealing resin 49 Second lead 400 Fixed contact 401 Pressing plate 402 Insulating porcelain tube 50 Movable contact 51 Conductive base material 52 Conductive member 53 Metal interface layer 60 Thermosensitive pellet-type thermal fuse 61 Cylindrical case 62 Thermosensitive pellet 63 Strong compression spring 64 Insulating cover 65 Weak compression spring 600 Fixed contact 66 First lead 67 Movable contact 68 Sealing resin 69 Second lead 601 Pressing plate 602 Insulating porcelain tube
