JP2016143643A - Protection element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a cutoff limit voltage more than ever before.SOLUTION: A protection element comprises a conductor 54 and a case 12. The conductor 54 blows out when a Joule heat integrated value becomes higher than or equal to a prescribed value. The case 12 houses the conductor 54. The protection element further comprises a contact material 14. The contact material 14 comes into contact with the conductor 54 and the case 12. The contact material 14 is housed in the case 12 together with the conductor 54. A space is formed in the case 12. When the conductor 54 comes into contact with the contact material 14, heat generated in the conductor 54 by electric conduction becomes easy to flow out to the outside of the conductor 54. The heat is easy to flow out to the outside, so an arc is cooled quickly after the conductor 54 has blown out. Moreover, the impact due to arc generation can be relieved. The arc can be cooled quickly and the impact due to arc generation can be relieved, so a cutoff limit voltage can be improved more than ever before.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a protective element such as a current fuse.

  Patent Document 1 discloses a current fuse. In this current fuse, a current fuse element is disposed at the center of a cylindrical case. Current fuse elements are supported by leads on both sides. The periphery of the current fuse element is covered with flux.

  According to the current fuse disclosed in Patent Document 1, oxidation of the surface of the current fuse element can be prevented.

Japanese Patent Laid-Open No. 11-213852

  However, the current fuse disclosed in Patent Document 1 has a problem that the cut-off limit voltage is low. The present invention solves such problems. An object of the present invention is to provide a protection element that improves the cutoff threshold voltage as compared with the prior art.

  The protection element of the present invention will be described with reference to the drawings. It should be noted that the reference numerals in the figure are used in this column in order to help understanding of the contents of the invention, and are not intended to limit the contents to the illustrated range.

  In order to solve the above-described problem, according to an aspect of the present invention, the protection element includes a conductor 54 and a case 12. The conductor 54 is melted when the Joule heat integration value is equal to or higher than a predetermined value. The case 12 accommodates the conductor 54. The protection element further includes a contact material 14. The contact material 14 contacts the conductor 54 and the case 12. The contact material 14 is accommodated in the case 12 together with the conductor 54. A space is formed in the case 12.

  When the conductor 54 is brought into contact with the contact material 14, heat generated in the conductor 54 due to energization easily flows out of the conductor 54 as compared to a case where the conductor 54 does not. Since heat tends to flow out, the arc is cooled sooner after the conductor 54 is melted than in other cases. Further, the space formed in the case 12 can mitigate the impact caused by the arc generation. Since the arc can be cooled quickly and the impact caused by the arc can be mitigated, the cut-off limit voltage can be improved as compared with the prior art.

  Moreover, it is desirable that the case 12 described above has at least one partition 42. The partition 42 partitions the inside of the case 12 so that a plurality of sections are arranged. In this case, it is desirable that the contact material 14 is in contact with the conductor 54 and the case 12 in any of the plurality of sections. In this case, it is desirable that a space be formed in a section adjacent to the section where the contact material 14 is in contact with the conductor 54 and the case 12.

  The inside of the case 12 is partitioned by a partition 42 so that a plurality of sections are arranged. A space is formed in a section adjacent to the section in which the contact material 14 is in contact with the conductor 54 and the case 12. By these, the space can be relieved of the impact caused by the generation of an arc when the conductor 54 is melted. Since the partition where the contact member 14 is in contact with the conductor 54 and the case 12 and the partition where the space is formed are partitioned by the partition 42, the contact member 14 is deformed when the contact member 14 is deformed as compared with the case where the contact member 14 is not. The possibility that the space is blocked by the deformation is low. Since the possibility that the space will be blocked is reduced, the possibility that the impact mitigation ability by the space is impaired is also reduced.

  Alternatively, it is desirable that the section where the contact material 14 described above is in contact with the conductor 54 and the case 12 and the section where the space is formed communicate with each other.

  When the section in which the contact material 14 is in contact with the conductor 54 and the case 12 communicates with the section in which the space is formed, the impact caused by the arc is directly transmitted by the communication. Thereby, compared with the case where these divisions are completely interrupted | blocked by the partition 42, an impact relaxation capability becomes high.

  Further, it is desirable that the case 12 described above has a heat radiator 40 in addition to the partition 42. The radiator 40 directly contacts the contact material 14 and absorbs the heat of the contact material 14. The radiator 40 emits heat to the outside of the case 12.

  When the radiator 40 is in direct contact with the contact material 14, the heat generated in the conductor 54 easily flows out of the conductor 54. Thereby, compared with the case where it is not so, an arc is cooled early after the conductor 54 fuses.

  Moreover, it is desirable to further include the coating resin 18 described above. The coating resin 18 covers the conductor 54 and the contact material 14. The coating resin 18 includes an inorganic filler and an epoxy resin. A part of the coating resin 18 covers at least a part of the inner peripheral surface of the case 12.

  When a part of the coating resin 18 covers at least a part of the inner peripheral surface of the case 12, the arc can be extinguished when the arc reaches the part. Thereby, generation | occurrence | production of the impact by an arc can be suppressed.

  Alternatively, it is desirable that the inner peripheral surface of the case 12 described above has the facing portion 36 and the surrounding portion 38. The facing portion 36 faces the conductor 54 and the contact material 14. The surrounding portion 38 surrounds the space between the facing portion 36 and the conductor 54 and the contact material 14. In this case, it is desirable that a part of the coating resin 18 covers at least a part of the facing part 36.

  When a part of the coating resin 18 covers at least a part of the facing part 36 of the case 12, the occurrence of an impact caused by an arc can be more effectively suppressed.

  Alternatively, it is desirable that the above-described inorganic filler contains alumina.

  Moreover, it is desirable that the contact material 14 described above contains a silicone resin.

  Alternatively, it is desirable that the above-described silicone resin contains silicone rubber.

  Alternatively, the contact material 14 described above preferably contains a metal oxide in addition to the silicone resin.

  Alternatively, the above-described metal oxide is desirably in the form of particles.

  Alternatively, it is desirable that the metal oxide described above contains alumina.

  According to the present invention, the cut-off limit voltage is improved as compared with the prior art.

It is a top view of a protection element concerning a certain embodiment of the present invention. It is a sectional view of a protection element concerning an embodiment with the present invention. It is a top view of the electroconductive part concerning one embodiment of the present invention. It is a perspective view of a case concerning an embodiment with the present invention. FIG. 3 is an enlarged view of FIG. 2.

  Hereinafter, the present invention will be described in detail with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

[Description of configuration]
FIG. 1 is a plan view of a protection element according to the present embodiment. In FIG. 1, a part of the contact material 14, a part of the coating resin 18, and a part of the back brazing material 66 are removed. FIG. 2 is a cross-sectional view of the protective element according to the present embodiment. In FIG. 2, the protection element according to the present embodiment is cut at the central portion. Based on FIG. 1 and FIG. 2, the structure of the protection element concerning this embodiment is demonstrated.

  The protection element according to this embodiment includes a conductive portion 10, a case 12, a contact material 14, and a coating resin 18. The conductive portion 10 is a portion through which current flows. The case 12 accommodates the conductive portion 10 and the contact material 14. The contact material 14 contacts the conductor 54 and the case 12. The covering resin 18 covers the conductive portion 10 accommodated in the case 12.

  FIG. 3 is a plan view of the conductive portion 10 according to the present embodiment. In FIG. 3, a part of the front brazing material 56 is removed. Based on FIG. 1 thru | or FIG. 3, the electroconductive part 10 concerning this embodiment is demonstrated. The conductive portion 10 according to the present embodiment includes a substrate 50, a pair of front electrodes 52, a conductor 54, a pair of front brazing materials 56, an alloy base 58, a low melting point alloy 60, and a pair of back electrodes 62. And a pair of lead wires 64 and a pair of back brazing members 66. The front electrode 52 is disposed on any surface of the substrate 50. In the present embodiment, the surface on which the front electrode 52 is disposed is regarded as the front surface of the substrate 50. In the present embodiment, a copper foil is fixed to the front surface of the substrate 50 as the front electrode 52. The conductor 54 is disposed on the front surface of the substrate 50. When the current flows, the conductor 54 heats a part of the energy of the current. The conductor 54 is naturally blown when the Joule heat integration value exceeds a predetermined value. The “Joule heat integration value” is energy required for fusing of a fuse element (in this embodiment, the conductor 54 corresponds to a “fuse element”). Since the formula for calculating the Joule heat integral value is well known, the description thereof will not be repeated here. In the case of this embodiment, the conductor 54 is a wire having one end connected to one of the front electrodes 52 and the other end connected to the other of the front electrodes 52. In the present embodiment, the conductor 54 is made of pure copper plated with tin. The front brazing material 56 connects the front electrode 52 and the conductor 54. Thereby, the surface electrode 52 and the conductor 54 conduct | electrically_connect. The alloy base 58 is fixed to the front surface of the substrate 50. The low melting point alloy 60 is disposed on the front surface of the substrate 50 in the same manner as the conductor 54. The low melting point alloy 60 is fixed to the substrate 50 via the alloy base 58. In the present embodiment, the low melting point alloy 60 covers the conductor 54 so as to straddle the central portion of the conductor 54. In the case of this embodiment, the “low melting point alloy” is an alloy having a melting point equal to or lower than the temperature at which the above-described conductor 54 is melted and in which the above-described conductor 54 is melted in a molten state. Such low melting point alloys are well known. Therefore, detailed description thereof will not be repeated here. The back electrode 62 is disposed on the surface of the substrate 50 that corresponds to the back as viewed from the front surface described above. In the present embodiment, this surface is regarded as the back surface of the substrate 50. In the case of this embodiment, the back electrode 62 is a copper foil like the front electrode 52. One of the pair of back electrodes 62 is disposed at a position corresponding to the back of one of the pair of front electrodes 52. The other of the pair of back electrodes 62 is disposed at a position corresponding to the other of the pair of front electrodes 52. One of the pair of lead wires 64 is connected to one of the pair of back electrodes 62. The other of the pair of lead wires 64 is connected to the other of the pair of back electrodes 62. The lead wire 64 penetrates the case 12. The back brazing material 66 connects the back electrode 62 and the lead wire 64. Thereby, the back electrode 62 and the lead wire 64 are electrically connected.

  The substrate 50 has a through hole 70. In the present embodiment, the substrate 50 has four through holes 70. One of the front electrode 52 and one of the back electrode 62 are connected to each other through two through holes 70. As a result, one of the front electrode 52 and one of the back electrode 62 are electrically connected. The other of the front electrode 52 and the other of the back electrode 62 are connected to each other through the other two through holes 70. Thereby, the other of the front electrode 52 and the other of the back electrode 62 conduct | electrically_connect. As a result, the current flowing through one of the lead wires 64 flows to the conductor 54 through one of the back electrode 62 and one of the front electrode 52. The current flowing through the conductor 54 flows through the other of the lead wires 64 through the other of the back electrode 62 and the other of the front electrode 52.

  FIG. 4 is a perspective view of the case 12 according to the present embodiment. The configuration of the case 12 according to the present embodiment will be described based on FIGS. 1, 2, and 4. The case 12 has an outer shell portion 30 and a reinforcing portion 32. The outer shell portion 30 accommodates the conductive portion 10. The reinforcing portion 32 suppresses deformation of the outer shell portion 30 when a force is applied to the outer shell portion 30.

  In the case of this embodiment, the outer shell 30 is made of synthetic resin. The inner peripheral surface of the outer shell portion 30 has a facing portion 36 and a surrounding portion 38. The facing portion 36 is a portion that becomes the bottom surface of the case 12. In the case 12, the above-described conductor 54 is disposed so as to face the facing portion 36 of the case 12. The low melting point alloy 60 also faces the facing portion 36. The surrounding portion 38 surrounds the space between the facing portion 36 and the conductor 54 and the contact material 14. As a result, the conductive portion 10 is disposed in a space surrounded by the facing portion 36 and the surrounding portion 38 in the case 12.

  The reinforcing portion 32 includes one heat radiator / reinforcing plate 40 and four partitions 42. In the case of this embodiment, the radiator / reinforcement plate 40 is made of alumina. In the case of this embodiment, the radiator / reinforcing plate 40 is obtained by sintering alumina. Therefore, in this embodiment, the heat radiator / reinforcement plate 40 has a higher thermal conductivity than the outer shell portion 30 made of synthetic resin. The radiator / reinforcement plate 40 absorbs the heat of the contact material 14. The radiator / reinforcement plate 40 releases the absorbed heat to the outside of the case 12 through the outer shell 30. In the case of this embodiment, the radiator / reinforcement plate 40 has a rectangular parallelepiped shape. In the case of this embodiment, the radiator / reinforcement plate 40 is fixed to the facing portion 36 on the inner peripheral surface of the outer shell portion 30. Thereby, the surface with the largest area of the radiator / reinforcement plate 40 faces the conductor 54. In the case of this embodiment, the four partitions 42 are integrated with the outer shell portion 30. The four partitions 42 protrude from the facing portion 36 of the outer shell portion 30. Of the four partitions 42, a pair is arranged so as to sandwich one end of the radiator / reinforcing plate 40. The other pair of the four partitions 42 is disposed so as to sandwich the other end of the radiator / reinforcement plate 40. There is a space between the partition 42 and the partition 42. Thereby, the spaces partitioned by the partition 42 communicate with each other.

  Based on FIG.2 and FIG.4, the contact material 14 concerning this embodiment is demonstrated. The contact material 14 is filled in a space from the heat radiator / reinforcement plate 40 of the case 12 to the conductor 54. The contact material 14 seals the conductor 54. In the present embodiment, the contact material 14 includes silicone rubber 80 and particulate alumina 82. In addition, it cannot be overemphasized that the contact material 14 has the electrical resistance of the grade which does not generate electric leakage.

  FIG. 5 is an enlarged view of FIG. The coating resin 18 according to the present embodiment will be described based on FIGS. 2, 4, and 5. The coating resin 18 is filled in the space from the outer peripheral portion of the conductive portion 10 of the case 12 to the edge of the enclosure portion 38. Thereby, as described above, the coating resin 18 covers the conductive portion 10 and the contact material 14 accommodated in the case 12. Part of the coating resin 18 flows into the inner peripheral surface of the outer shell portion 30 from the gap between the outer peripheral portion of the conductive portion 10 and the surrounding portion 38. In the case of this embodiment, a part of the coating resin 18 reaches the facing portion 36 on the inner peripheral surface of the outer shell portion 30. In the case of this embodiment, the coating resin 18 includes an epoxy resin and particulate alumina. This particulate alumina is contained in the coating resin 18 as an inorganic filler.

[Description of manufacturing method]
The protection element manufacturing method according to the present embodiment includes a conductive part forming step, a contact material applying step, a case housing step, and a covering step. The conductive part 10 is formed in the conductive part forming step. The specific process for forming the conductive portion 10 is the same as that of a well-known protective element formed on the substrate, and therefore detailed description thereof will not be repeated here. In the contact material application step, a mixture of silicone rubber and particulate alumina is applied to the conductor 54 of the conductive portion 10. The silicone rubber in this mixture is cured after being applied. The cured mixture becomes the contact material 14. In the case housing step, first, the radiator / reinforcement plate 40 is fixed to the outer shell portion 30 of the case 12. The outer shell 30 is manufactured in advance by injection molding. The outer shell 30 to which the radiator / reinforcing plate 40 is fixed is the case 12. The case 12 is placed on the conductive portion 10. Thereby, in the middle section of the sections of the outer shell portion 30, the mixture applied in the contact material application step contacts the conductor 54 and the radiator / reinforcement plate 40. In the section adjacent to the section, the partition 42 prevents the mixture from entering, so that a space is formed. Thereafter, the mixture applied in the contact material application step is cured. The cured mixture becomes the contact material 14. In the coating step, the case 12 is filled with a mixture of epoxy resin that has not yet been cured and particulate alumina. Thereby, the conductive part 10 in the case 12 is covered. Thereafter, the filled mixture is cured. The mixture after curing becomes the coating resin 18.

[Description of usage]
The method of using the protection element according to this embodiment is the same as that of a known current fuse. That is, the protection element according to the present embodiment is connected to a circuit (not shown). When a large current in a predetermined range flows through the conductor 54, the temperature of the conductor 54 exceeds a predetermined temperature. The conductor 54 is melted when the Joule heat integration value is equal to or higher than a predetermined value. When an arc occurs after fusing, the arc is extinguished inside the protective element. As a result, the current is interrupted in the circuit to which the protection element is connected.

[Description of Examples]
Example 1
Five protective elements described above were prepared. However, in the case housing step, after the radiator / reinforcement plate 40 was fixed to the outer shell portion 30, a mixture of epoxy resin and particulate alumina was applied to the facing portion 36 and the surrounding portion 38. The composition of this mixture was the same component as the mixture filled in the coating process. This mixture was applied to reproduce the situation where a part of the coating resin 18 flowed into the inner peripheral surface of the outer shell portion 30 from the gap between the outer peripheral portion of the conductive portion 10 and the surrounding portion 38 and reached the facing portion 36. It is to do. As a result, a layer of the coating resin 18 was formed on the surface of the facing portion 36 and the surface of the surrounding portion 38. Test piece numbers “1” to “5” were set for each protection element.

(Example 2)
Two protective elements as described above were prepared. However, in the case housing step, after the heat radiator / reinforcing plate 40 was fixed to the outer shell 30, a mixture of epoxy resin and particulate alumina was applied to the enclosure 38. The composition of this mixture was the same component as the mixture filled in the coating process. The mixture was not applied to the facing portion 36. This mixture was applied to reproduce the situation where a part of the coating resin 18 flowed into the inner peripheral surface of the outer shell portion 30 from the gap between the outer peripheral portion of the conductive portion 10 and the surrounding portion 38 and reached the surrounding portion 38. It is to do. As a result, a layer of the coating resin 18 was formed on the surface of the surrounding portion 38. The layer of the coating resin 18 was not formed on the surface of the facing portion 36. A test piece number of “1” or “2” was set for each protection element.

(Comparative Example 1)
Except for the two points described below, ten protective elements having the same structure as the protective element according to Example 1 were prepared. The first point is that the mixture was not applied in the contact material application process. As a result, this protective element did not include the contact material 14. The second point is that the mixture was not applied to the facing portion 36 and the surrounding portion 38 in the case accommodation process. As a result, in this protective element, the coating resin 18 layer was not formed on the surface of the facing portion 36 and the surface of the surrounding portion 38. Test piece numbers of “1” to “10” were set for each protection element.

(Comparative Example 2)
Except for the two points described below, eight protective elements having the same structure as the protective element according to Example 1 were prepared. The first point is that the mixture is applied so as to fill the case 12 in the contact material application step. As a result, no space was formed in the case 12 in this protective element. The second point is that the mixture was not applied to the facing portion 36 and the surrounding portion 38 in the case accommodation process. As a result, in this protective element, the coating resin 18 layer was not formed on the surface of the facing portion 36 and the surface of the surrounding portion 38. Test piece numbers of “1” to “8” were set for each protection element.

(Measurement of cut-off limit voltage)
With the protective elements according to Example 1, Example 2, Comparative Example 1, and Comparative Example 2, the cut-off limit voltage was measured. The measurement was carried out by a method in which direct currents having a current value of 50 amperes and different voltage values were passed through the respective protection elements. As a result of the direct current flowing, the protective element that satisfies any of the following requirements was determined to be unacceptable. The first requirement is that the leakage current exceeds 2.5 milliamps. The second requirement is to ignite. The third requirement is a requirement that an appearance problem such as destruction occurs. The fourth requirement is that the insulation resistance is less than 0.2 MΩ. A protective element that did not satisfy any of these requirements was determined to be acceptable. Moreover, the insulation resistance of each protection element was measured after the measurement of the cut-off limit voltage. Table 1 shows a list of measurement results.

  As shown in Table 1, in the case of the protective element according to Example 1, any device in which a direct current having a voltage value of 490 volts or less was passed was determined to be acceptable. A battery with a DC voltage of 500 volts ignited. Therefore, the cut-off limit voltage of the protective element according to Example 1 was determined to be 490 volts. In the case of the protective element according to Example 2, a device in which a direct current having a voltage value of 450 volts was passed was determined to be acceptable. A battery with a DC value of 460 volts ignited. Therefore, the cut-off limit voltage of the protective element according to Example 2 was determined to be 450 volts. In the case of the protective element according to Comparative Example 1, any device that passed a direct current having a voltage value of 240 volts or less was determined to be unacceptable. This is because the insulation resistance is less than 0.2 MΩ and the leakage current exceeds 2.5 milliamperes. A problem in appearance occurred when a DC current having a voltage value of 260 volts was passed. That is, it was determined as rejected. Therefore, since all the protective elements according to Comparative Example 1 failed, the cutoff limit voltage was determined to be less than 100 volts. In the case of the protective element according to Comparative Example 2, any device that passed a DC current having a voltage value of 420 volts or less was determined to be acceptable. Among those in which a direct current having a voltage value of 430 volts was passed, there was a problem in appearance. Therefore, the cut-off limit voltage of the protective element according to Comparative Example 2 was determined to be 420 volts.

  As is clear from the results in Table 1, the protection element provided with the contact material 14 has a significantly higher cutoff limit voltage than the protection element that does not. Among the protective elements provided with the contact material 14, the protective element in which the space is formed has a higher cut-off limit voltage than the protective element that is not. Among the protective elements provided with the contact material 14 and having a space, the protective element in which the layer of the coating resin 18 is formed in the facing portion 36 has a cut-off threshold voltage compared to a protective element that does not. high. Therefore, it can be said that the protection element including the contact material 14 and having a space has a higher cut-off limit voltage than the protection element that is not. Among these, it can be said that the case where the layer of the coating resin 18 is formed on the inner peripheral surface of the outer shell portion 30 has a particularly high cutoff threshold voltage. As a result, when a part of the mixture filled in the case 12 in the covering step enters between the facing portion 36 and the conductive portion 10, the cutoff voltage is higher than that without such entry. . In particular, when a part of the mixture filled in the case 12 in the covering step reaches the facing portion 36, the cutoff limit voltage becomes high.

[Description of effects]
In the protection element according to the present embodiment, when the conductor 54 is in contact with the contact material 14, heat generated in the conductor 54 due to energization easily flows out of the conductor 54 compared to the case where the conductor 54 is not. . Since heat tends to flow out, the arc is cooled sooner after the conductor 54 is melted than when the heat is not so. The space formed in the case 12 can mitigate the impact caused by the generation of an arc. Since the arc can be cooled quickly and the impact caused by the arc can be mitigated, the cut-off limit voltage can be improved as compared with the prior art.

  In the protection element according to the present embodiment, the inside of the case 12 is partitioned by the partition 42 so that a plurality of sections are arranged. The contact member 14 is in contact with the conductor 54 and the radiator / reinforcement plate 40 in the middle of the compartments of the outer shell 30 inside the case 12. By these, the space can be relieved of the impact caused by the generation of an arc when the conductor 54 is melted. Since the section where the contact member 14 contacts the conductor 54 and the heat sink / reinforcing plate 40 and the section where the space is formed are partitioned by the partition 42, the contact member 14 is deformed as compared with the case where it is not. Sometimes the possibility of the space being blocked by the deformation is low. Since the possibility that the space will be blocked is reduced, the possibility that the impact mitigation ability by the space is impaired is also reduced.

  In the protection element according to the present embodiment, the section in which the conductor 54 is disposed and the section in which the space is formed communicate with each other, so that an impact caused by the generation of an arc is directly transmitted through the communication. Thereby, compared with the case where these divisions are completely interrupted | blocked by the partition 42, an impact relaxation capability becomes high.

  In the protection element according to the present embodiment, since the radiator / reinforcement plate 40 is in direct contact with the contact material 14, the heat generated in the conductor 54 easily flows out of the conductor 54. Thereby, compared with the case where it is not so, an arc is cooled early after the conductor 54 fuses. In addition, since the protection element according to the present embodiment includes the heat sink / reinforcement plate 40 made of alumina, the mechanical strength of the case 12 is higher than that in the case where it is not.

  In the protection element according to the present embodiment, part of the coating resin 18 covers the facing portion 36 of the case 12, so that when the arc reaches the arc, the arc can be extinguished. This is because the coating resin 18 contains alumina. Thereby, generation | occurrence | production of the impact by an arc can be suppressed.

  In the protection element according to the present embodiment, when a current flows through the conductor 54, the conductor 54 heats a part of the energy of the current. Heat is transferred to the alumina 82, the silicone rubber 80, and the low melting point alloy 60 of the contact material 14. Since it is in contact with the contact material 14, the heat generated in the conductor 54 easily flows out to the alumina 82 and the silicone rubber 80 as compared with the case where the surrounding is a space. The heat spreads throughout the contact material 14 through the particulate alumina 82. Thereby, the temperature rise of the conductor 54 can be suppressed effectively.

  In the protection element according to the present embodiment, since the contact material 14 includes the silicone rubber 80, it is possible to suppress deterioration of the contact material 14 due to heat compared to the case where the contact material 14 includes another synthetic resin having poor heat resistance.

<Description of modification>
The above-described protective element is illustrated to embody the technical idea of the present invention. The protection element described above can be variously modified within the scope of the technical idea of the present invention.

  For example, the shape and material of the heat radiator / reinforcing plate 40 described above are not particularly limited. That is, the radiator / reinforcement plate 40 may be a sintered metal oxide other than alumina. The radiator / reinforcement plate 40 may be manufactured by a method other than sintering. The protective element may not include the heat radiator / reinforcement plate 40.

  Moreover, the contact material 14 mentioned above may also contain fibrous alumina. The contact material 14 may contain a metal oxide other than alumina. Examples of metal oxides other than alumina include silica sand and titanium oxide. In this case, if the metal oxide has a thermal conductivity equal to or higher than that of alumina, heat can be quickly transferred to the entire contact material 14. The contact material 14 may not contain a metal oxide.

  Further, the substance contained in the contact material 14 described above is not limited to the silicone rubber 80. For example, a silicone resin other than the silicone rubber 80 may be used. Polymers other than silicone resins may be used. When the contact material 14 contains a polymer and a metal oxide, those ratios are not limited. When the contact material 14 contains a polymer and a metal oxide, it is preferable that the volume% of the metal oxide is higher than the volume% of the polymer. Regardless of the composition of the contact material 14, the metal oxide is preferably contained in an amount of 50% by mass or more.

  Further, the components of the coating resin 18 described above are not limited to those described above. For example, the coating resin may include other inorganic fillers instead of the above-described alumina. The coating resin may include another synthetic resin instead of the epoxy resin.

  Further, the configuration and form of the conductive unit 10 described above are not limited to those described above.

10 ... conductive part,
12 ... Case,
14 ... contact material,
18 ... Coating resin,
30 ... outer shell,
32 ... reinforcement part,
36 ... opposite part,
38 ... enclosure,
40 ... radiator and reinforcing plate,
42 ... partition,
50 ... a substrate,
52 ... front electrode,
54. Conductor,
56 ... front brazing material,
58 ... Alloy base,
60 ... low melting point alloy,
62 ... back electrode,
64 ... lead wire,
66 ... Back brazing material,
70 ... through hole,
80 ... silicone rubber,
82 ... particulate alumina,

Claims (12)

A conductor that melts when the Joule heat integration value exceeds a predetermined value;
A protective element comprising a case for housing the conductor,
A contact member that contacts the conductor and the case and is accommodated in the case together with the conductor;
A protective element, wherein a space is formed in the case. The case has at least one partition that divides the inside of the case so that a plurality of sections are arranged,
The contact material is in contact with the conductor and the case in any of the plurality of sections;
The protection element according to claim 1, wherein the space is formed in the section adjacent to the section where the contact material is in contact with the conductor and the case.   The protection element according to claim 2, wherein the section in which the contact material is in contact with the conductor and the case communicates with the section in which the space is formed.   2. The case according to claim 1, further comprising a radiator that directly contacts the contact material, absorbs heat of the contact material, and releases the heat to the outside of the case, in addition to the partition. The protective element as described. A coating resin for coating the conductor and the contact material;
The coating resin is
An inorganic filler;
Including epoxy resin,
The protective element according to claim 1, wherein a part of the coating resin covers at least a part of an inner peripheral surface of the case. The inner peripheral surface of the case is
A facing portion facing the conductor and the contact material;
An enclosure that surrounds the space between the opposing portion and the conductor and the contact material;
The protective element according to claim 5, wherein a part of the coating resin covers at least a part of the facing part.   The protective element according to claim 5, wherein the inorganic filler contains alumina.   The protective element according to claim 1, wherein the contact material includes a silicone resin.   The protective element according to claim 8, wherein the silicone resin includes silicone rubber.   The protective element according to claim 8, wherein the contact material includes a metal oxide in addition to the silicone resin.   The protective element according to claim 10, wherein the metal oxide is in the form of particles.   The protective element according to claim 10 or 11, wherein the metal oxide contains alumina.

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