Protection element

Abstract

To reduce the risk of malfunction when a large current accidentally flows.SOLUTION: A protection element 14 includes a case 42, a thermal fuse element 34, and a current fuse element 36. The thermal fuse element 34 is housed in the case 42. The current fuse element 36 is housed in the case 42. The current fuse element 36 has a higher melting point than the thermal fuse element 34. The thermal fuse element 34 and the current fuse element 36 are connected in parallel.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a protection element used, for example, in high voltage direct current transmission. [Background technology]

[0002] Patent Document 1 discloses a current fuse. This current fuse has a main fuse element and a sub-fuse element with a melting point higher than that of the main fuse element, the resistance value of the main fuse element is equal to or lower than the resistance value of the sub-fuse element, and the main fuse element and the sub-fuse element are connected in parallel. The current fuse disclosed in Patent Document 1 can improve the rating and prevent explosive scattering of low-melting point metal due to arc discharge. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-76295 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the current fuse disclosed in Patent Document 1 has a problem in that if a large current accidentally flows, it may malfunction and cut off the current.

[0005] The present invention is intended to solve such problems, and has an object to provide a protection element that reduces the risk of malfunction when a large current accidentally flows through it. [Means for solving the problem]

[0006] The protective element of the present invention will be described with reference to the drawings. Note that the reference numerals in the drawings are used in this section to facilitate understanding of the contents of the invention, and are not intended to limit the contents to the scope of the drawings.

[0007] In order to solve the above-mentioned problems, according to one aspect of the present invention, the protection element 14 has a case 42, a thermal fuse element 34, and a current fuse element 36. The thermal fuse element 34 is housed in the case 42. The current fuse element 36 is housed in the case 42. The current fuse element 36 has a higher melting point than the thermal fuse element 34. The thermal fuse element 34 and the current fuse element 36 are connected in parallel.

[0008] The protection element 14 according to an aspect of the present invention can be connected to any load 12. When the protection element 14 is connected to the load 12, abnormal heat may be generated in the load 12. At least a part of the abnormal heat is transferred to the temperature fuse element 34 through the case 42. When the temperature fuse element 34 melts due to the transfer of the heat, the current path through the protection element 14 according to an aspect of the present invention is cut off. At this point, the current path through the current fuse element 36 is not cut off. This is because the temperature fuse element 34 and the current fuse element 36 are connected in parallel, and the temperature fuse element 34 has a lower melting point than the current fuse element 36. When the current path through the protection element 14 according to an aspect of the present invention is cut off, the current through that current path flows through the current fuse element 36. As a result, when a current exceeding the rated current flows through the current fuse element 36, the current fuse element 36 melts due to self-heating. That is, the protective element 14 according to an aspect of the present invention cuts off the current path when it receives a large current in addition to heat. On the other hand, the current fuse element 36 is unlikely to melt until the temperature fuse element 34 melts. This is because a part of the current flowing through the protective element 14 flows through the temperature fuse element 34, and the current flowing through the current fuse element 36 is reduced. As the current flowing through the current fuse element 36 is reduced, the possibility that the current fuse element 36 will melt is reduced even if a large current temporarily flows through the current fuse element 36. The protective element 14 according to an aspect of the present invention cuts off the current path when it receives a large current in addition to heat. As a result, the protective element 14 is provided in which the risk of malfunction is reduced when a large current accidentally flows. Furthermore, the protective element 14 according to an aspect of the present invention has a case 42. Both the temperature fuse element 34 and the current fuse element 36 are housed in the case 42.This reduces the likelihood that arcs that occur when the thermal fuse element 34 and the current fuse element 36 melt will propagate around the protection device 14 according to certain aspects of the present invention.

[0009] moreover The above-mentioned protection element 14 further includes a metal one-end connector 38 and a metal other-end connector 40. do. One end of the temperature fuse element 34 and one end of the current fuse element 36 are connected to the one-end connector 38. The other end of the temperature fuse element 34 and the other end of the current fuse element 36 are connected to the other-end connector 40. In this case, the temperature fuse element 34 and the current fuse element 36 are connected in parallel by the one-end connector 38 and the other-end connector 40. do. In this case, the one-end connector 38 has a one-end base portion 100 and a one-end protrusion portion 102. do. The one-end protrusion 102 protrudes from one end of the one-end base 100. In this case, one end of the temperature fuse element 34 is connected to the one-end protrusion 102. One end of the current fuse element 36 is connected to the one-end base 100. In this case, the other-end connector 40 has the other-end base 104 and the other-end protrusion 106. do. The other end projection 106 projects from one end of the other end base portion 104. In this case, the other end of the temperature fuse element 34 is connected to the other end projection 106. The other end of the current fuse element 36 is connected to the other end base portion 104.

[0010] Until the temperature fuse element 34 melts, heat from the load 12 to which the protection element 14 is connected is transferred to the current fuse element 36 via the one-end connector 38 and the other-end connector 40. The one-end connector 38 and the other-end connector 40 are made of metal. As a result, the one-end connector 38 and the other-end connector 40 have high thermal conductivity, so that heat from the load 12 to which the protection element 14 is connected is efficiently transferred to the current fuse element 36. As the heat is transferred to the current fuse element 36, the temperature of the current fuse element 36 rises. This reduces the probability of the current fuse element 36 not melting even though a large current is flowing because the current fuse element 36 cannot achieve a sufficient temperature rise in a harsh environment. Furthermore, after the temperature fuse element 34 melts, the one-end protrusion 102 and the other-end protrusion 106 receive heat from the load 12 to which the protection element 14 is connected. The one-end protrusion 102 protrudes from one end of the one-end base 100. The other-end protrusion 106 protrudes from one end of the other-end base 104. As a result, the one-end connector 38 and the other-end connector 40 can receive more heat from the load 12 to which the protection element 14 is connected, compared to a case in which the one-end connector 38 does not have the one-end protrusion 102 and the other-end connector 40 does not have the other-end protrusion 106. Since the one-end connector 38 and the other-end connector 40 can receive more heat, the probability of the current fuse element 36 not achieving a sufficient temperature rise is reduced. As a result, the protection element 14 is provided with a reduced risk of malfunction, such as the circuit not being cut off despite a large current flowing.

[0011] It is also desirable that the above-mentioned thermal fuse element 34 has the following mechanical strength. The mechanical strength is such that plastic deformation of the current fuse element 36 can be prevented when one of the one-end connector 38 and the other-end connector 40 is supported and the other is not supported. In this case, it is desirable that the mechanical strength of the one-end connector 38 and the other-end connector 40 is equal to or greater than the mechanical strength of the thermal fuse element 34.

[0012] If the thermal fuse element 34 has the mechanical strength described above, then by grasping either the thermal fuse element 34, the one end connector 38, or the other end connector 40, the entirety of these can be supported without plastically deforming the current fuse element 36. This makes it easier to move the entirety of these components compared to when the thermal fuse element 34 does not have the mechanical strength described above.

[0013] According to another aspect of the present invention, the protection element 14 has a thermal fuse element 34 and a current fuse element 36. The current fuse element 36 has a higher melting point than the thermal fuse element 34. The resistance value of the thermal fuse element 34 is equal to or less than the resistance value of the current fuse element 36. The thermal fuse element 34 and the current fuse element 36 are connected in parallel. Furthermore, the above-mentioned protective element 14 further has a metallic one-end connector 38 and a metallic other-end connector 40. One end of the temperature fuse element 34 and one end of the current fuse element 36 are connected to the one-end connector 38. The other end of the temperature fuse element 34 and the other end of the current fuse element 36 are connected to the other-end connector 40. In this case, the temperature fuse element 34 and the current fuse element 36 are connected in parallel by the one-end connector 38 and the other-end connector 40. In this case, the one-end connector 38 has a one-end base 100 and a one-end protruding portion 102. The one-end protruding portion 102 protrudes from one end of the one-end base 100. In this case, one end of the temperature fuse element 34 is connected to the one-end protruding portion 102. One end of the current fuse element 36 is connected to the one-end base 100. In this case, the other-end connector 40 has an other-end base 104 and an other-end protrusion 106. The other-end protrusion 106 protrudes from one end of the other-end base 104. In this case, the other end of the temperature fuse element 34 is connected to the other-end protrusion 106. The other end of the current fuse element 36 is connected to the other-end base 104.

[0014] The protection element 14 according to another aspect of the present invention can be connected to any load 12. When the protection element 14 is connected to the load 12, abnormal heat may be generated in the load 12. When at least a part of the abnormal heat is transmitted to the temperature fuse element 34 and the temperature fuse element 34 melts, the current path through the protection element 14 according to another aspect of the present invention is interrupted. At this point, the current path through the current fuse element 36 is not interrupted. This is because the temperature fuse element 34 and the current fuse element 36 are connected in parallel, and the temperature fuse element 34 has a lower melting point than the current fuse element 36. When the current path through the protection element 14 according to another aspect of the present invention is interrupted through the temperature fuse element 34, the current through that current path flows through the current fuse element 36 by that amount. As a result, when a current exceeding the rated current flows through the current fuse element 36, the current fuse element 36 melts due to self-heating. That is, the protective element 14 according to another aspect of the present invention cuts off the current path when it receives a large current in addition to heat. On the other hand, the current fuse element 36 is unlikely to melt until the temperature fuse element 34 melts. This is because a part of the current flowing through the protective element 14 flows through the temperature fuse element 34, and the current flowing through the current fuse element 36 is reduced accordingly. Moreover, the resistance value of the temperature fuse element 34 is equal to or less than the resistance value of the current fuse element 36. As a result, the current flowing through the current fuse element 36 is significantly suppressed until the temperature fuse element 34 melts. As a result, even if a large current temporarily flows through the current fuse element 36, the possibility that the current fuse element 36 will melt due to the current being significantly suppressed is reduced. The protective element 14 according to another aspect of the present invention cuts off the current path when it receives a large current in addition to heat. As a result, a protective element 14 is provided that is less likely to malfunction when a large current accidentally flows through it. In addition, until the temperature fuse element 34 melts, heat from the load 12 to which the protection element 14 is connected is transferred to the current fuse element 36 via the one-end connector 38 and the other-end connector 40. The one-end connector 38 and the other-end connector 40 are made of metal. As a result, the one-end connector 38 and the other-end connector 40 have high thermal conductivity, so that heat from the load 12 to which the protection element 14 is connected is efficiently transferred to the current fuse element 36. As the heat is transferred to the current fuse element 36, the temperature of the current fuse element 36 rises. This reduces the probability of the current fuse element 36 not melting even though a large current is flowing because the current fuse element 36 cannot achieve a sufficient temperature rise in a harsh environment. Furthermore, after the temperature fuse element 34 melts, the one-end protrusion 102 and the other-end protrusion 106 receive heat from the load 12 to which the protection element 14 is connected. The one-end protrusion 102 protrudes from one end of the one-end base 100. The other-end protrusion 106 protrudes from one end of the other-end base 104. As a result, the one-end connector 38 and the other-end connector 40 can receive more heat from the load 12 to which the protection element 14 is connected, compared to a case in which the one-end connector 38 does not have the one-end protrusion 102 and the other-end connector 40 does not have the other-end protrusion 106. Since the one-end connector 38 and the other-end connector 40 can receive more heat, the probability of the current fuse element 36 not achieving a sufficient temperature rise is reduced. As a result, the protection element 14 is provided with a reduced risk of malfunction, such as the circuit not being cut off despite a large current flowing. Effect of the Invention

[0015] According to the present invention, the risk of malfunction occurring when a large current accidentally flows is reduced. [Brief description of the drawings]

[0016] [Figure 1] 1 is a circuit diagram of a circuit including a protection element according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a diagram showing a configuration of a protection element according to an embodiment of the present invention. [Diagram 3] 1 is a first diagram showing a temperature fuse element, a current fuse element, a one-end connector, and an other-end connector of a protection element according to an embodiment of the present invention. FIG. [Figure 4] 2 is a second diagram showing a temperature fuse element, a current fuse element, one end connector, and the other end connector of a protection element according to an embodiment of the present invention. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] The present invention will be described in detail below with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are the same. Therefore, detailed descriptions thereof will not be repeated.

[0018] [Circuit description] Fig. 1 is a circuit diagram of a circuit including a protection element 14 according to this embodiment. Fig. 1 shows one terminal 30, the other terminal 32, a temperature fuse element 34, and a current fuse element 36, which are components of the protection element 14 according to this embodiment. The configuration of the circuit including the protection element 14 according to this embodiment will be described with reference to Fig. 1.

[0019] The circuit shown in FIG. 1 includes a DC high-voltage power supply 10, a load 12, and a protection element 14 according to this embodiment. The DC high-voltage power supply 10 supplies high-voltage DC power. The load 12 performs a predetermined operation and generates heat. The protection element 14 according to this embodiment cuts off the power supply to the load 12 when predetermined requirements are met. There are two requirements, which are described below. One of the requirements is that the protection element 14 according to this embodiment receives a predetermined amount of heat due to an abnormality occurring in the operation of the load 12 or for other reasons. The other requirement is that a predetermined amount of power is supplied to the protection element 14 according to this embodiment due to an abnormality occurring in the operation of the load 12 or for other reasons.

[0020] [Configuration Description] Fig. 2 is a diagram showing the configuration of the protection element 14 according to this embodiment. In Fig. 2, most of the arc-extinguishing material 50 and most of the coating resin 52 have been removed. The configuration of the protection element 14 according to this embodiment will be described with reference to Fig. 2.

[0021] The protective element 14 in this embodiment includes one terminal 30, the other terminal 32, a temperature fuse element 34, a current fuse element 36, one end connector 38, the other end connector 40, a case 42, a ceramic body 44, a main flux 46, a sub-flux 48, an arc-extinguishing material 50, and a coating resin 52.

[0022] One terminal 30 and the other terminal 32 are conductors provided for connecting an electric circuit. In the present embodiment, one terminal 30 is connected to a DC high voltage power supply 10. The other terminal 32 is connected to a load 12. This results in high voltage DC power being supplied to one terminal 30 and the other terminal 32. The details of one terminal 30 and the other terminal 32 are the same as well-known terminals, and therefore a detailed description thereof will not be repeated here.

[0023] In this embodiment, the thermal fuse element 34 functions as a thermal fuse. As a result, the thermal fuse element 34 of this embodiment melts when it receives heat and reaches its own melting point. The resistance value (electrical resistance value) of the thermal fuse element 34 of this embodiment is so small that it is difficult to melt it by a temperature rise based on the power supplied to it. The details of the thermal fuse element 34 itself are the same as those of known fuse elements, so a detailed description thereof will not be repeated here.

[0024] In this embodiment, the current fuse element 36 is connected in parallel with the temperature fuse element 34. In this embodiment, the current fuse element 36 has a function of a current fuse. As a result, the current fuse element 36 according to this embodiment melts due to self-heating when a current exceeding the rated value flows. In this embodiment, the current fuse element 36 melts at a temperature higher than the temperature at which the temperature fuse element 34 melts. That is, the melting point of the current fuse element 36 according to this embodiment is higher than the melting point of the temperature fuse element 34. Furthermore, in this embodiment, the resistance value of the current fuse element 36 exceeds the resistance value of the temperature fuse element 34. The details of the current fuse element 36 itself are the same as those of a known fuse element, so a detailed description thereof will not be repeated here.

[0025] In this embodiment, one end of the temperature fuse element 34 and one end of the current fuse element 36 are connected to the one-end connector 38. In this embodiment, the one-end connector 38 is made of copper. This allows a current to flow to the temperature fuse element 34 and the current fuse element 36 via the one-end connector 38.

[0026] In this embodiment, the other end of the temperature fuse element 34 and the other end of the current fuse element 36 are connected to the other end connector 40. In this embodiment, the material of the other end connector 40 is the same as the material of the one end connector 38. This allows current to flow to the temperature fuse element 34 and the current fuse element 36 via the other end connector 40.

[0027] In this embodiment, the case 42 is made of synthetic resin or ceramic. The case 42 accommodates an end of the one terminal 30, an end of the other terminal 32, the temperature fuse element 34, the current fuse element 36, the one-end connector 38, the other-end connector 40, and the ceramic body 44. As is clear from Fig. 2, a groove 88 is formed in a side wall 82 of the case 42 according to this embodiment, through which the one terminal 30 or the other terminal 32 passes.

[0028] The ceramic body 44 is housed in the case 42 together with the temperature fuse element 34, the current fuse element 36, the one end connector 38, and the other end connector 40. In this embodiment, the ceramic body 44 is rectangular and plate-like. The ceramic body 44 is disposed on the bottom 80 of the case 42. In this case, the ceramic body 44 is disposed so as to face the space formed between the temperature fuse element 34 and the current fuse element 36. The details of the ceramic body 44 itself are the same as those of a known ceramic plate, and therefore a detailed description thereof will not be repeated here.

[0029] The main flux 46 covers the thermal fuse element 34. The details of the main flux 46 itself are the same as known fluxes, so the detailed description thereof will not be repeated here.

[0030] The sub-flux 48 coats the current fuse element 36. The details of the sub-flux 48 itself are the same as known fluxes, so a detailed description thereof will not be repeated here.

[0031] The arc-extinguishing material 50 is filled inside the case 42, particularly between the temperature fuse element 34 and the current fuse element 36. As a result, in this embodiment, the arc-extinguishing material 50 is placed on the ceramic body 44 so as to cover the entire surface thereof. When an arc occurs in at least one of the temperature fuse element 34 and the current fuse element 36, the arc-extinguishing material 50 cools the arc. This extinguishes the arc. In this embodiment, the arc-extinguishing material 50 is mainly composed of silicone rubber. In this embodiment, the arc-extinguishing material 50 contains particulate alumina as an additive. It goes without saying that the arc-extinguishing material 50 has an electrical resistance that does not cause leakage current.

[0032] The coating resin 52 is filled inside the case 42 when the following two requirements are satisfied. One of the requirements is that the end of the one terminal 30, the end of the other terminal 32, the temperature fuse element 34, the current fuse element 36, the one-end connector 38, the other-end connector 40, and the ceramic body 44 are accommodated in the case 42. The temperature fuse element 34 is covered with the main flux 46. The current fuse element 36 is covered with the sub-flux 48. The other requirement is that the arc-extinguishing material 50 is filled inside the case 42. As a result, the coating resin 52 is filled inside the case 42, and thus the end of the one terminal 30, the end of the other terminal 32, the temperature fuse element 34, the current fuse element 36, the one-end connector 38, the other-end connector 40, and the ceramic body 44 are fixed inside the case 42.

[0033] Fig. 3 is a first diagram showing the temperature fuse element 34, the current fuse element 36, the one-end connector 38, and the other-end connector 40 of the protection element 14 according to this embodiment. Fig. 4 is a second diagram showing the temperature fuse element 34, the current fuse element 36, the one-end connector 38, and the other-end connector 40 of the protection element 14 according to this embodiment. What is shown in Fig. 4 is a rear view of what is shown in Fig. 3. The temperature fuse element 34, the current fuse element 36, the one-end connector 38, and the other-end connector 40 according to this embodiment will be described based on Figs. 3 and 4.

[0034] As is clear from Figures 3 and 4, the one-end connector 38 according to this embodiment has a one-end base 100 and a one-end protrusion 102. In this embodiment, these are integrated. One end of the current fuse element 36 is connected to the one-end base 100. The one-end protrusion 102 protrudes from one end of the one-end base 100. One end of the temperature fuse element 34 is connected to the one-end protrusion 102.

[0035] In this embodiment, the one-end base 100 has a one-end connection body 120 and a one-end overhang 122. In this embodiment, these are integrated. The one-end terminal 30 is fixed to the one-end connection body 120. This fixation allows current to flow from the one-end terminal 30 to the one-end connection body 38. In this embodiment, the rectangular portion of the one-end connection body 38 shown in Figures 3 and 4 that includes the portion where the one-end terminal 30 is fixed and extends in a direction perpendicular to the direction in which the one-end terminal 30 extends becomes the one-end connection body 120. In this embodiment, the one-end overhang 102 described above is connected to one end of the one-end connection body 120 of the one-end base 100. The one-end overhang 122 is connected to the other end of the one-end connection body 120. The one-end overhang 122 extends in the same direction as the one-end overhang 102. In this embodiment, the one-end projection 122 merely projects from the other end of the one-end connection body 120 and, by extension, the other end of the one-end base 100, and therefore cannot be said to actually project, since the extending distance is less than the one-end projection 102. In this embodiment, one end of the current fuse element 36 is connected to the one-end projection 122.

[0036] As is clear from Figures 3 and 4, the other-end connector 40 according to this embodiment has an other-end base 104 and an other-end protrusion 106. In this embodiment, these are integrated. The other end of the current fuse element 36 is connected to the other-end base 104. The other-end protrusion 106 protrudes from one end of the other-end base 104. The other end of the temperature fuse element 34 is connected to the other-end protrusion 106.

[0037] In this embodiment, the other end base 104 has an other end connection body 124 and an other end protruding portion 126. In this embodiment, these are integrated. The other terminal 32 is fixed to the other end connection body 124. This fixation allows current to flow from the other end connection body 40 to the other terminal 32. In this embodiment, the rectangular portion of the other end connection body 40 shown in Figures 3 and 4 that includes the part where the other terminal 32 is fixed and extends in a direction perpendicular to the direction in which the other terminal 32 extends becomes the other end connection body 124. In this embodiment, the above-mentioned other end protruding portion 106 is connected to one end of the other end connection body 124 of the other end base 104. The other end protruding portion 126 is connected to the other end of the other end connection body 124. The other end protruding portion 126 extends in the same direction as the other end protruding portion 106. In this embodiment, the other end protruding portion 126 merely protrudes from the other end of the other end connection body 124 and, by extension, the other end of the other end base portion 104, and therefore cannot be said to protrude. In this embodiment, the other end of the current fuse element 36 is connected to the other end protruding portion 126.

[0038] As described above, in this embodiment, one end of the temperature fuse element 34 and the tip of the one-end protrusion 102 are connected to each other. The other end of the temperature fuse element 34 and the tip of the other-end protrusion 106 are connected to each other. As a result, the one-end protrusion 102, the temperature fuse element 34, and the other-end protrusion 106 are linearly connected. In this embodiment, the temperature fuse element 34 has the following mechanical strength. The mechanical strength is such that plastic deformation of the current fuse element 36 can be prevented when one of the one-end connector 38 and the other-end connector 40 is supported and the other is not supported. In this embodiment, the mechanical strength of the one-end connector 38 and the other-end connector 40 is equal to or greater than the mechanical strength of the temperature fuse element 34.

[0039] In this embodiment, the current fuse element 36 is connected to the one end connector 38 and the other end connector 40 by solder having a lower melting point. The reason why the current fuse element 36 is connected by such solder is that when the current fuse element 36 melts, a tensile force is applied to the current fuse element 36 by the tension of the already molten solder. When a tensile force is applied to the current fuse element 36, the possibility of an arc occurring after the current fuse element 36 melts can be reduced.

[0040] In this embodiment, the one-end connector 38 has the following mechanical strength. The mechanical strength is such that it does not bend even when any part of the one-end base 100 is supported. Since the one-end connector 38 does not bend even when any part of the one-end base 100 is supported, the temperature fuse element 34 and the current fuse element 36 are maintained apart from each other even when any part of the one-end base 100 is supported. In this embodiment, the other-end connector 40 has the following mechanical strength. The mechanical strength is such that it does not bend even when any part of the other-end base 104 is supported. Since the other-end connector 40 does not bend even when any part of the other-end base 104 is supported, the temperature fuse element 34 and the current fuse element 36 are maintained apart from each other even when any part of the other-end base 104 is supported.

[0041] [Production method description] In this embodiment, the one-end connector 38 and the other-end connector 40 are formed by performing known machining on a copper blank. In other respects, the manufacturing method of the protection element 14 according to this embodiment is similar to that of known protection elements. Therefore, the detailed description thereof will not be repeated here.

[0042] [Instructions for use] The protection element 14 according to this embodiment is used in the same manner as a known protection element. That is, the protection element 14 according to this embodiment is connected to the circuit shown in Fig. 1, for example. The protection element 14 according to this embodiment cuts off the power supply to the load 12 when a predetermined requirement is satisfied. In this way, the circuit to which the protection element 14 according to this embodiment is connected is protected.

[0043] [Effect description] When a current flows through the protective element 14 according to this embodiment, the current flows through the thermal fuse element 34 and the current fuse element 36 via one terminal 30. The current that has flowed through the thermal fuse element 34 and the current fuse element 36 flows through the other terminal 32. As a result, the circuit to which the protective element 14 according to this embodiment is connected becomes conductive.

[0044] Thereafter, the load 12 generates heat as it operates. Part of the heat is transferred to the protection element 14 according to this embodiment. The thermal fuse element 34 melts when it reaches its own melting point due to the heat it receives. At that time, the current fuse element 36 remains conductive. Even if an arc occurs in the thermal fuse element 34 when it melts, the arc is extinguished by the arc-extinguishing material 50.

[0045] When the path of the current flowing through the protective element 14 according to the present embodiment that passes through the temperature fuse element 34 is cut off, the current flowing through that path will flow through the current fuse element 36. As a result, when a current exceeding the rated current flows through the current fuse element 36, the current fuse element 36 melts due to self-heating. That is, the protective element 14 according to the present embodiment cuts off the path of the current when it receives a large current in addition to heat. On the other hand, the current fuse element 36 is difficult to melt until the temperature fuse element 34 melts off. This is because a part of the current flowing through the protective element 14 flows through the temperature fuse element 34, and the current flowing through the current fuse element 36 becomes smaller. As the current flowing through the current fuse element 36 becomes smaller, the possibility that the current fuse element 36 will melt down due to the smaller current is reduced even if a large current temporarily flows through the current fuse element 36. The protective element 14 according to the present embodiment cuts off the path of the current when it receives a large current in addition to heat. As a result, a protective element 14 is provided that is less likely to malfunction when a large current accidentally flows through it.

[0046] Furthermore, the protective element 14 according to this embodiment has a case 42. Both the temperature fuse element 34 and the current fuse element 36 are housed in the case 42. This reduces the possibility that an arc generated when the temperature fuse element 34 and the current fuse element 36 melt will spread around the protective element 14 according to this embodiment.

[0047] Heat transmitted from the load 12 is transmitted to the current fuse element 36 via the one-end connector 38 and the other-end connector 40. In this embodiment, the one-end connector 38 and the other-end connector 40 are made of copper. As a result, the one-end connector 38 and the other-end connector 40 have high thermal conductivity, so that heat from the load 12 to which the protection element 14 is connected is efficiently transmitted to the current fuse element 36. As the heat is transmitted to the current fuse element 36, the temperature of the current fuse element 36 increases. This reduces the probability of occurrence of a situation in which the current fuse element 36 does not melt even when a large current is flowing because the current fuse element 36 cannot achieve a sufficient temperature increase in, for example, a harsh environment (an example of a harsh environment is an extremely cold environment in which the heat generated in the current fuse element 36 is gradually lost).

[0048] In addition, in the protective element 14 according to this embodiment, after the temperature fuse element 34 melts, the one-end protrusion 102 and the other-end protrusion 106 receive heat from the load 12 to which the protective element 14 is connected. The one-end protrusion 102 protrudes from one end of the one-end base 100. The other-end protrusion 106 protrudes from one end of the other-end base 104. As a result, the one-end connector 38 and the other-end connector 40 can receive more heat from the load 12 to which the protective element 14 is connected, compared to a case in which the one-end connector 38 does not have the one-end protrusion 102 and the other-end connector 40 does not have the other-end protrusion 106. Since the one-end connector 38 and the other-end connector 40 can receive more heat, the probability of the current fuse element 36 not achieving a sufficient temperature rise is reduced. As a result, a protective element 14 is provided that is less likely to malfunction, such as a circuit not being cut off despite a large current flowing.

[0049] Furthermore, in the protective element 14 according to this embodiment, when any one of the thermal fuse element 34, the one end connector 38, and the other end connector 40 is gripped, these can be supported as a whole without causing plastic deformation of the current fuse element 36. This makes it easier for these to move as a whole, compared to a case in which the thermal fuse element 34 does not have the above-mentioned mechanical strength.

[0050] Furthermore, in the protective element 14 according to this embodiment, the ceramic body 44 is disposed so as to face the space formed between the temperature fuse element 34 and the current fuse element 36. As a result, even if an arc occurs as a result of the melting of the temperature fuse element 34, or even if an arc occurs as a result of the melting of the current fuse element 36, the generated arc is cooled. As a result, the arc is extinguished. Since the arc is extinguished, the safety of the protective element 14 is improved.

[0051] <Description of Modified Examples> The above-described protective element 14 is exemplified to embody the technical idea of ​​the present invention. Various modifications can be made to the above-described protective element 14 within the scope of the technical idea of ​​the present invention.

[0052] For example, the material of the one end connector 38 and the material of the other end connector 40 are not limited to copper. These materials may be aluminum, copper, silver, gold, tin, iron, nickel, or an alloy containing at least one of aluminum, copper, silver, gold, tin, iron, and nickel as a main component. These materials may be other metals. These materials may also be metal members plated with at least one of tin, nickel, copper, silver, and gold. Note that the "main component" here means the component that occupies the highest proportion in the alloy. Therefore, when the main components are aluminum, copper, silver, gold, tin, iron, and nickel, the proportions of the main components in the alloy are equal. Of course, the alloy may contain multiple types of aluminum, copper, silver, gold, tin, iron, and nickel, and one of these types may occupy a larger proportion in the alloy than the others.

[0053] The configurations of the one-end connector 38 and the other-end connector 40 are not limited to those described above. Therefore, for example, the one-end base 100 may have a portion that extends in the same direction as the one-end protrusion 102 and has an extending distance equal to or greater than that of the one-end protrusion 102, instead of the one-end overhang 122.

[0054] In addition, both the one end connector 38 and the other end connector 40 must have the above-mentioned mechanical strength. do not have However, only one of the one end connector 38 and the other end connector 40 may have the mechanical strength to maintain the temperature fuse element 34 and the current fuse element 36 separated from each other when the portion where the temperature fuse element 34 is connected and the portion where the current fuse element 36 is connected are supported.

[0055] In addition, the above-described protective element 14 may not have the case 42. Furthermore, the above-described protective element 14 may not include the one terminal 30, the other terminal 32, the ceramic body 44, the main flux 46, the sub-flux 48, the arc-extinguishing material 50, and the coating resin 52. [Explanation of symbols]

[0056] 10...DC high voltage power supply 12. Load 14...Protection element 30...One terminal 32...Other terminal 34...Thermal fuse element 36...Current fuse element 38...One end connector 40...Other end connector 42…Case 44…Ceramic body 46…Main Flux 48...Subflux 50...Arc extinguishing material 52...Coating resin 80...Bottom 100...One end base 102...Protrusion on one end side 104...Other end side base 106...Other end protrusion 120...One end connection body 122...One end overhang 124...Other end connection body 126...Other end overhang

Claims

1. Case and a thermal fuse element housed in the case; a current fuse element housed in the case and having a melting point higher than that of the temperature fuse element; A protection element in which the temperature fuse element and the current fuse element are connected in parallel.

2. a metallic one-end connector to which one end of the temperature fuse element and one end of the current fuse element are connected; a metal other end connector to which the other end of the temperature fuse element and the other end of the current fuse element are connected, the temperature fuse element and the current fuse element are connected in parallel by the one end connector and the other end connector, The one end connector is One end side base portion, a one-end side protrusion protruding from one end of the one-end side base portion, One end of the thermal fuse element is connected to the one end protrusion, One end of the current fuse element is connected to the one end base portion, The other end connector is A base portion on the other end side; and an other end side protruding portion protruding from one end of the other end side base portion, The other end of the thermal fuse element is connected to the other end protrusion, 2. The protection element according to claim 1, wherein the other end of the current fuse element is connected to the other end base portion.

3. the temperature fuse element has a mechanical strength capable of preventing plastic deformation of the current fuse element when one of the one end connector and the other end connector is supported and the other is not supported, 3. The protection element according to claim 2, wherein the mechanical strength of the one end connector and the other end connector is equal to or greater than the mechanical strength of the thermal fuse element.

4. A thermal fuse element; a current fuse element having a melting point higher than that of the temperature fuse element, The resistance value of the temperature fuse element is equal to or less than the resistance value of the current fuse element, A protection element in which the temperature fuse element and the current fuse element are connected in parallel.

Images