JP6816874B2 - Protective element - Google Patents

Description

The present invention relates to a protective element.

Patent Document 1 discloses an invention relating to a protective element. The protective element according to Patent Document 1 includes a pair of electrodes, a heating piece, a bonding material, a resistor, and an elastic body. The pair of electrodes are arranged so as to face each other. The heating pieces are arranged so as to straddle the pair of electrodes. The heating piece generates heat when an electric current flows. As the bonding material, the heat generating pieces are bonded to each of the pair of electrodes. The resistor generates heat when an electric current flows through it. This causes the resistor to act as a heat source. The elastic body is placed between the pair of electrodes. The elastic body applies a separating force to the heating piece. The separating force is the force in the direction in which the heating piece separates from the pair of electrodes. The strength of the bonding material falls below a predetermined strength at a predetermined temperature. The predetermined temperature is a temperature reached by the heat generated by the heating piece. The predetermined strength is the strength to withstand the separating force. The protective element further includes a shielding insulator and a magnetic field generating portion. The shielding insulator is arranged between the pair of electrodes so as to block the other when viewed from one of the pair of electrodes. The magnetic field generator generates a magnetic force in advance between the pair of electrodes.

In the protective element disclosed in Patent Document 1, the heating piece is separated from the electrode by the elastic body. As a result, the current between the electrodes is cut off. When an arc is generated between the electrodes after the current is cut off, the arc receives Lorentz force due to the magnetic force generated by the magnetic field generator. The arc is extended by receiving the Lorentz force. Further, when viewed from one of the pair of electrodes, the other is shielded by a shielding insulator. Since it is blocked by the shielding insulator, the arc emitted from one of the pair of electrodes reaches the other electrode after avoiding the shielding insulator. The arc extends because it avoids shielding insulation. When the arc is extended due to the Lorentz force and the arc avoiding the shielding insulator, the arc voltage is higher than when it is not extended. Also, the arc is cooled by being extended. The synergistic effect of rising arc voltage and cooling the arc makes it difficult for the arc to sustain. As a result, a large current can be passed through the protective element disclosed in Patent Document 1.

Japanese Unexamined Patent Publication No. 2013-98134

However, in the protection element disclosed in Patent Document 1, there is room for improvement in the allowable voltage of the resistor. In the conventional protection element, the allowable voltage of the resistor is significantly smaller than the allowable voltage of the electrode. This is one of the causes of spending a great deal of effort on insulation measures between electrodes and resistors. The present invention has been made to solve such a problem. An object of the present invention is to facilitate an increase in the allowable voltage of a protective element including an electrode and a resistor.

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

In order to solve the above-mentioned problems, according to a certain aspect of the present invention, the protective element 10 comprises a pair of electrodes 22 and 24, an energizing body 26, a bonding material 28, an elastic body 32, and a heating body 40. Be prepared. The pair of electrodes 22 and 24 are arranged so as to face each other. The energizing body 26 is arranged so as to straddle the pair of electrodes 22 and 24. The energizing body 26 is in a state where a current can flow between the pair of electrodes 22 and 24. The joining material 28 joins the energizing body 26 to each of the pair of electrodes 22 and 24. The elastic body 32 is arranged between the pair of electrodes 22 and 24. The elastic body 32 applies a separating force to the energizing body 26. The heating body 40 generates heat transferred to the bonding material 28. The separating force is a force in the direction in which the energizing body 26 separates from the pair of electrodes 22 and 24. The bonding strength of the bonding material 28 is lower than the predetermined strength at a predetermined temperature. The predetermined temperature is a temperature reached by the heat generated by the heating body 40. The predetermined strength is the strength to withstand the separating force. The heating body 40 has a plurality of winding resistors 70 and 72 connected in series with each other.

When the heating body 40 has a plurality of winding resistors 70 and 72 connected in series with each other, heat is generated in the heating body 40 as compared with the case where the heating body 40 has one winding resistor. The locations will be dispersed. When the places where heat is generated are dispersed, the resistance values of the individual winding resistors 70 and 72 required to equalize the temperature distribution on the surface of the object receiving heat from the heating body 40 are set to one winding resistance. It can be made smaller than the resistance value of the winding resistor of the heating body 40 having the device. If the resistance values of the individual winding resistors 70 and 72 can be reduced, the windings of the winding resistors 70 and 72 can be thickened. The thicker the winding, the higher the permissible voltage of that winding. As a result, it is possible to facilitate an increase in the allowable voltage of the resistor in the protective element including the electrode and the resistor.

Further, any of the plurality of the wire-wound resistor 70, 72 described above, Ru near the resistor 70 der. The proximity resistor 70 is arranged closer to the bonding member 28 than the other winding resistor 72. The proximity resistor 70 has a higher electrical resistance than the other winding resistors 72.

When a nearby resistor 70 having a higher electrical resistance than other winding resistors is arranged near the joint material 28, a plurality of winding resistors 70 and 72 are generated as compared with the case described below. The heat easily flows to the bonding material 28. In that case, the electrical resistance of any of the other winding resistors is higher than that of the nearby resistor 70. As a result, the thermal efficiency for operating the protective element 10 becomes higher than in the case where the heat flows to an object other than the bonding material 28.

Alternatively, it is desirable that the above-mentioned proximity resistor 70 is arranged between the pair of electrodes 22 and 24.

When the proximity resistor 70 is arranged between the pair of electrodes 22 and 24, the heat generated by the proximity resistor 70 tends to flow to any of the pair of electrodes 22 and 24 as compared with the case described below. The case is a case where any single region of the surface of the nearby resistor 70 faces both of the pair of electrodes 22 and 24. The heat flowing through the pair of electrodes 22 and 24 flows through the bonding material 28. As a result, the thermal efficiency for operating the protection element 10 becomes higher than in the case where any single region of the surface of the near resistor 70 faces both of the pair of electrodes 22 and 24.

Further, it is desirable that the heating body 40 described above further has an insulating solid 74 for heat transfer. The heat transfer insulating solid 74 surrounds a plurality of winding resistors 70 and 72. The heat transfer insulating solid 74 comes into contact with each of the plurality of winding resistors 70 and 72. The heat transfer insulating solid 74 contacts at least one of the pair of electrodes 22, 24.

The heat transfer insulating solid 74 comes into contact with each of the plurality of winding resistors 70 and 72. The heat transfer insulating solid 74 contacts at least one of the pair of electrodes 22, 24. As a result, the heat generated by the winding resistors 70 and 72 is transferred to at least one of the pair of electrodes 22 and 24 via the heat transfer insulating solid 74. Solids transfer heat more easily than gases. As a result, the heat generated by the plurality of winding resistors 70 and 72 is generated by the pair of electrodes 22, as compared with the case where the space between the pair of electrodes 22 and 24 and the winding resistors 70 and 72 is provided. It becomes easy to flow to 24. The heat flowing through the pair of electrodes 22 and 24 flows through the bonding material 28. As a result, the thermal efficiency for operating the protection element 10 is higher than in the case where the space between the plurality of winding resistors 70 and 72 and the pair of electrodes 22 and 24 is formed.

Alternatively, it is desirable that at least one of the pair of electrodes 22 and 24 described above has the heated body facing planes 50 and 52. The heating body facing planes 50 and 52 face the heating body 40. In this case, it is desirable that the heat transfer insulating solid 74 has contact planes 92 and 94 and an exposed plane 90. The contact planes 92 and 94 come into contact with the heated body facing planes 50 and 52. The exposure plane 90 is exposed in a space in contact with the heating body 40.

The exposed plane 90 is exposed in the space in contact with the heating body 40. The contact planes 92 and 94 come into contact with the heated body facing planes 50 and 52. The heated body facing planes 50 and 52 are provided by at least one of the pair of electrodes 22 and 24. As a result, the heat generated by the heating body 40 is more likely to be transferred to the heating body facing planes 50 and 52 with which the contact planes 92 and 94 are in contact than in the space where the exposed plane 90 is exposed. The exposed plane 90 has a smaller surface area than the convex surface on which it projects toward the exposed space. The exposed plane 90 has a smaller surface area than the concave surface that is recessed when viewed from the exposed space. The small surface area makes it difficult for heat to flow into space. As a result, the thermal efficiency for operating the protection element 10 is increased.

According to the present invention, it is possible to facilitate an increase in the allowable voltage of a protective element having an electrode and a resistor.

It is a perspective view of the protection element which concerns on an embodiment of this invention in a state where a part is removed. It is a side view of the protection element which concerns on an embodiment of this invention. It is an external view of the vicinity of a heating body according to an embodiment of the present invention. It is external drawing of the intermediate material in a certain embodiment of this invention. It is a figure which shows the energized body immediately after being separated from a positive electrode and a negative electrode in a certain embodiment of this invention.

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

[Description of configuration]
FIG. 1 is a perspective view of the protective element 10 according to the present embodiment. In FIG. 1, the protective element 10 is shown in an assembled state. In this figure, a part of the case 46 of the protective element 10 is removed. The configuration of the protection element 10 according to the present embodiment will be described with reference to FIG. The protective element 10 according to the present embodiment includes an insulating base 20, a positive electrode 22, a negative electrode 24, an energizing body 26, a bonding material 28, a lead insulator 30, a compression coil spring 32, and a spring insulator. A 34, a first lead terminal 36, a second lead terminal 38, a heating body 40, a tubular support 42, a pair of block-shaped permanent magnets 44, and a case 46 are provided.

The insulating base 20 is a member made of synthetic resin used as a base. The insulating base 20 has heat resistance to the extent that it is not deformed by the heat generated by the heating body 40. The positive electrode 22 and the negative electrode 24 are fixed to the insulating base 20. By being fixed to the insulating base 20, the positive electrode 22 and the negative electrode 24 are arranged so as to face each other. Further, the insulating base 20 has a first lead support portion 56 and a second lead support portion 58.

In the case of this embodiment, the positive electrode 22 and the negative electrode 24 are connected to a well-known power line (not shown). A power line is an electric wire for supplying electric power to a load. A load (not shown) is connected to the power line. An example of such a load is a motor. When a current flows between the positive electrode 22 and the negative electrode 24, a current flows through the power line. Power is supplied to the load by the current flowing through the power line.

In the case of the present embodiment, the positive electrode 22 has a plane facing the heating body on the positive electrode side 50. The negative electrode 24 has a flat surface 52 facing the heating body on the negative electrode side. The positive electrode side heating body facing plane 50 and the negative electrode side heating body facing plane 52 face the heating body 40.

In the case of the present embodiment, the energizing body 26 is arranged so as to straddle the positive electrode 22 and the negative electrode 24. That is, when the protective element 10 is assembled, the energizing body 26 is joined to both the tip of the positive electrode 22 and the tip of the negative electrode 24. The energizing body 26 is made of metal. Therefore, the energizing body 26 is joined to the positive electrode 22 and the negative electrode 24 so that a current can flow between the positive electrode 22 and the negative electrode 24. In the case of the present embodiment, holes (not shown) are formed in the energized body 26 where neither the positive electrode 22 nor the negative electrode 24 is joined.

The joining material 28 joins the energizing body 26 to the positive electrode 22. In the case of the present embodiment, another bonding material 28 joins the current-carrying body 26 to the negative electrode 24. In the case of the present embodiment, the bonding strength of the bonding material 28 is lower than the predetermined strength at a predetermined temperature. In the case of the present embodiment, the "predetermined temperature" is the temperature reached by the heat generated by the heating body 40. In the case of the present embodiment, the "predetermined strength" is a strength that can withstand the separating force. In the case of the present embodiment, the "separation force" is a force in the direction in which the energizing body 26 bonded to the positive electrode 22 and the negative electrode 24 is separated from the positive electrode 22 and the negative electrode 24. In the case of this embodiment, this separating force is applied by the compression coil spring 32. In the case of this embodiment, the bonding material 28 is an alloy having the above-mentioned "predetermined temperature" as a melting point. The designer of the protective element 10 according to the present embodiment can select any alloy whose bonding strength is lower than a predetermined strength at a predetermined temperature as the bonding material 28 from among the well-known alloys.

The lead insulator 30 is arranged between the current-carrying body 26 and the compression coil spring 32. In the case of this embodiment, the lead insulator 30 is fixed to the current-carrying body 26. A hole (not shown) is opened in the center of the lead insulator 30. This hole communicates with the hole of the energizing body 26.

The compression coil spring 32 is arranged at a position that satisfies the following requirements. The first requirement is that it is between the energizing body 26 and the heating body 40. The second requirement is that it is between the positive electrode 22 and the negative electrode 24. The compression coil spring 32 applies a force in the direction away from the positive electrode 22 and the negative electrode 24 to the energizing body 26. Therefore, the compression coil spring 32 is in a compressed state until the bonding strength of the bonding material 28 falls below the predetermined strength described above. In the case of this embodiment, the compression coil spring 32 is made of stainless steel (that is, made of a conductor).

The spring insulator 34 is arranged between the compression coil spring 32 and the heating body 40. The spring insulator 34 prevents the compression coil spring 32 from coming into direct contact with the heating body 40. As a result, the compression coil spring 32 and the heating body 40 are insulated from each other. There is a hole (not shown) in the center of the spring insulator 34.

The first lead terminal 36 and the second lead terminal 38 are fixed to the insulating base 20. The first lead terminal 36 and the second lead terminal 38 are connected to the heating body 40 and a well-known signal line (not shown). The signal line is an electric wire for controlling the heating body 40. When a current flows through the signal line, a current also flows through the first lead terminal 36 and the second lead terminal 38. When a current flows through the first lead terminal 36 and the second lead terminal 38, a current flows through the heating body 40.

The heating body 40 is arranged so as to be sandwiched between the positive electrode 22 and the negative electrode 24. The heating body 40 is connected to the first lead terminal 36 and the second lead terminal 38. When a current flows through the first lead terminal 36 and the second lead terminal 38, a current also flows through the heating body 40. The heating body 40 generates heat when an electric current flows through it. As a result, the heating body 40 acts as a heat source.

The tubular support 42 is arranged between the heating body 40 and the second lead support 58. In the case of this embodiment, the tubular support 42 is a tubular member. The tubular support 42 supports the heating body 40 that receives a force from the compression coil spring 32.

The block-shaped permanent magnet 44 generates a magnetic force. The pair of block-shaped permanent magnets 44 are arranged so as to sandwich the positive electrode 22 and the negative electrode 24. Therefore, the space in which the pair of the block-shaped permanent magnets 44 generates a magnetic force includes the space between the positive electrode 22 and the negative electrode 24. Therefore, a magnetic force is generated between the positive electrode 22 and the negative electrode 24. By generating a magnetic force, even if an arc is generated when the energizing body 26 is separated from the positive electrode 22 and the negative electrode 24, the arc can be efficiently cooled.

The case 46 includes an insulating base 20, a part of a positive electrode 22, a part of a negative electrode 24, an energizing body 26, a bonding material 28, a lead insulator 30, a compression coil spring 32, and a spring insulator. It covers 34, a part of the first lead terminal 36, a part of the second lead terminal 38, a heating body 40, a tubular support 42, and a block-shaped permanent magnet 44. The case 46 is also a component for fixing the block-shaped permanent magnet 44 in a predetermined position. The material of the case 46 is a synthetic resin. The case 46 has a magnet accommodating portion (not shown). The block-shaped permanent magnet 44 is housed in the magnet housing part.

FIG. 2 is a side view of the protective element 10 according to the present embodiment. In FIG. 2, the negative electrode 24, a part of the heating body 40, and a part of the case 46 are removed. The configuration of the heating body 40 according to the present embodiment will be described with reference to FIG.

The heating element 40 according to the present embodiment includes a nearby resistor 70, a low resistance value resistor 72, a heat transfer insulating solid 74, a first lead wire 76, a second lead wire 78, and a ceramic plate 80. have. In the case of this embodiment, both the proximity resistor 70 and the low resistance value resistor 72 are winding resistors. The winding resistor according to this embodiment is one in which a resistance wire is wound around a ceramic score (not shown). The proximity resistor 70 is arranged between the positive electrode 22 and the negative electrode 24. The proximity resistor 70 generates heat when electric power is supplied. The proximity resistor 70 is arranged closer to the bonding material 28 than the low resistance value resistor 72. In the case of this embodiment, the proximity resistor 70 has a higher electrical resistance than the low resistance value resistor 72. The low resistance value resistor 72 is also arranged between the positive electrode 22 and the negative electrode 24, similarly to the proximity resistor 70. The low resistance value resistor 72 is connected in series with the nearby resistor 70. The low resistance value resistor 72 generates heat when electric power is supplied. In the case of this embodiment, the material of the heat transfer insulating solid 74 is a synthetic resin. In the case of this embodiment, the heat transfer insulating solid 74 is filled between the positive electrode 22 and the negative electrode 24. Therefore, the heat transfer insulating solid 74 surrounds the proximity resistor 70 and the low resistance value resistor 72. Further, the heat transfer insulating solid 74 comes into contact with the nearby resistor 70 and the low resistance value resistor 72, respectively. The heat transfer insulating solid 74 also comes into contact with the positive electrode 22 and the negative electrode 24. As a result, the heat generated by the proximity resistor 70 and the low resistance value resistor 72 is transferred to the bonding material 28 via the positive electrode 22 and the negative electrode 24. The first lead wire 76 is connected to the nearby resistor 70. The first lead wire 76 penetrates the hole of the lead insulator 30 and the hole of the energizing body 26. Since the inner diameter of the hole of the lead insulator 30 is smaller than the inner diameter of the hole of the energizing body 26, the first lead wire 76 and the energizing body 26 are insulated from each other. Further, the first lead wire 76 penetrates the hole of the spring insulator 34 and the compression coil spring 32. The first lead wire 76 is connected to the first lead terminal 36. The first lead wire 76 is supported by the first lead support portion 56 of the insulating base 20. The second lead wire 78 is connected to the low resistance value resistor 72 and the second lead terminal 38. The second lead wire 78 is supported by the second lead support portion 58 of the insulating base 20. The second lead wire 78 penetrates the tubular support 42. The ceramic plate 80 reinforces the heat transfer insulating solid 74.

FIG. 3 is an external view of the vicinity of the heating body 40 according to the present embodiment. In FIG. 3, a part of the negative electrode 24 is removed. The configuration of the heat transfer insulating solid 74 according to the present embodiment will be described with reference to FIGS. 2 and 3.

The heat transfer insulating solid 74 according to the present embodiment has an exposed plane 90, a negative electrode contact plane 92, and a positive electrode contact plane 94 (see FIG. 5). In the case of the present embodiment, the exposed plane 90 faces the insulating base 20 in the direction opposite to that of the heat transfer insulating solid 74. The exposed plane 90 is exposed in the space in contact with the heating body 40. In the case of this embodiment, the exposed plane 90 is orthogonal to the negative electrode contact plane 92 and the positive electrode contact plane 94. The negative electrode contact plane 92 contacts the negative electrode side heating body facing plane 52 of the negative electrode 24. The positive electrode contact plane 94 contacts the positive electrode side heating body facing plane 50 of the positive electrode 22.

[Explanation of manufacturing method]
The manufacturing method of the protective element 10 according to the present embodiment is as follows. First, among the protective elements 10 according to the present embodiment, the manufacturer describes the insulating base 20, the positive electrode 22, the negative electrode 24, the current-carrying body 26, the lead insulator 30, the compression coil spring 32, and the spring. An insulator 34, a first lead terminal 36, a second lead terminal 38, a pair of block-shaped permanent magnets 44, and a case 46 are manufactured. Since these manufacturing methods are well known, the detailed description thereof will not be repeated here. Next, the manufacturer fixes the negative electrode 24, the first lead terminal 36, and the second lead terminal 38 on the insulating base 20. Next, the manufacturer joins the energizing body 26 to the end of the negative electrode 24 with the joining material 28. In the case of this embodiment, the bonding material 28 is a well-known alloy. When the energizing body 26 is joined to the end of the negative electrode 24, the manufacturer connects the first lead wire 76 to the first lead terminal 36. The manufacturer connects the second lead wire 78 to the second lead terminal 38. Next, the manufacturer accommodates the proximity resistor 70, the low resistance value resistor 72, the first lead wire 76, the second lead wire 78, and the ceramic plate 80 in a mold (not shown). When the work of accommodating in the mold is completed, the manufacturer manufactures the intermediate material 130 by molding using the mold. FIG. 4 is an external view of the intermediate material 130. When the intermediate material 130 is manufactured, the manufacturer sets the first lead wire 76 of the intermediate material 130 to the hole of the current-carrying body 26, the hole of the lead insulator 30, the compression coil spring 32, and the spring insulator. It penetrates through the holes of 34. When the first lead wire 76 of the intermediate material 130 penetrates them, the manufacturer allows the second lead terminal 38 to penetrate the tubular support 42. When the second lead terminal 38 penetrates the tubular support 42, the manufacturer causes the intermediate member 130 to be supported by the first lead support portion 56 and the second lead support portion 58. The manufacturer places the intermediate material 130 on the insulating base 20. When the intermediate material 130 is placed on the insulating base 20, the manufacturer fixes the positive electrode 22 on the insulating base 20. Next, the manufacturer joins the current-carrying body 26 to the end of the positive electrode 22 by the joining material 28. When the energizing body 26 is joined to the end portion of the positive electrode 22, the manufacturer injects a synthetic resin between the intermediate material 130 and the positive electrode 22 and the negative electrode 24 from the outside of the positive electrode 22. When the synthetic resin is solidified, the object composed of the solidified synthetic resin and the intermediate material 130 becomes the heating body 40. When the synthetic resin solidifies, the manufacturer fixes the case 46, which previously houses the pair of block-shaped permanent magnets 44, to the insulating base 20. As a result, the protective element 10 according to the present embodiment is completed.

[Explanation of usage]
An example of how to use the protective element 10 according to this embodiment is as follows. First, the user connects the protection element 10 according to the present embodiment to a circuit (not shown) to be protected. It is assumed that the circuit is for letting a motor or other load do the work. The circuit has a power line, a sensor, a control device, and a signal line. A power line is an electric wire for supplying electric power to a load (an example of a load is a motor). The sensor detects anomalies presumed by the designer of this circuit. The control device operates the protection element 10 according to the present embodiment in response to the sensor detecting the abnormality. The signal line is an electric wire for connecting the control device and the heating body 40 of the protection element 10 according to the present embodiment. The user connects the positive electrode 22 and the negative electrode 24 of the protective elements 10 according to the present embodiment to the power line. The user connects the first lead terminal 36 and the second lead terminal 38 to the signal line. As a result, the protective element 10 according to this embodiment becomes usable. During use of this circuit, the power line powers the load. This power is supplied from a power source (not shown). When the sensor detects the above-mentioned abnormality during power supply, the control device causes a current to flow through the signal line to the first lead terminal 36 and the second lead terminal 38 of the protection element 10 according to the present embodiment. .. The current flows through the heating body 40. When an electric current flows through the heating body 40, the heating body 40 generates heat. As a result of the heating body 40 generating heat, when the joining strength of the joining material 28 falls below a predetermined strength, the compression coil spring 32 separates the energizing body 26 from the positive electrode 22 and the negative electrode 24. FIG. 5 is a diagram showing an energizing body 26 immediately after being separated from the positive electrode 22 and the negative electrode 24 (the structure inside the heating body 40 is omitted in this figure). When the energizing body 26 separates from the positive electrode 22 and the negative electrode 24, the current flowing through the power line is cut off. When the current is cut off, the power supply to the load is stopped.

[Explanation of effect]
As described above, in the protection element 10 according to the present embodiment, the heating element 40 has a proximity resistor 70 and a low resistance value resistor 72. When the heating element 40 has a nearby resistor 70 and a low resistance value resistor 72, the places where heat is generated in the heating element 40 are dispersed as compared with the case where the heating element 40 has one winding resistor. It will be. When the places where heat is generated are dispersed, the resistance values of the nearby resistor 70 and the low resistance value resistor 72, which are necessary to equalize the temperature distribution on the surface of the object that receives heat from the heating body 40, are wound in one roll. It can be made smaller than the resistance value of the winding resistor of the heating body 40 having the wire resistor. If the resistance value between the proximity resistor 70 and the low resistance value resistor 72 can be reduced, the windings of the proximity resistor 70 and the low resistance value resistor 72 can be made thicker. The thicker the winding, the higher the permissible voltage of that winding. As a result, it is possible to facilitate an increase in the allowable voltage between the near-range resistor 70 and the low resistance value resistor 72 in the protection element 10 according to the present embodiment.

Further, in the protective element 10 according to the present embodiment, when a nearby resistor 70 having a higher electric resistance than the low resistance value resistor 72 is arranged near the bonding material 28, it is closer than in the case described below. The heat generated by the resistor 70 and the low resistance value resistor 72 easily flows to the bonding material 28. In that case, the electric resistance of the low resistance value resistor 72 is higher than that of the nearby resistor 70. As a result, the thermal efficiency for operating the protective element 10 becomes higher than in the case where the heat flows to an object other than the bonding material 28.

Further, in the protection element 10 according to the present embodiment, when the proximity resistor 70 is arranged between the positive electrode 22 and the negative electrode 24, the heat generated by the proximity resistor 70 is generated by the positive electrode 22 as compared with the case described below. And the negative electrode 24 can easily flow. In that case, the positive electrode 22 and the negative electrode 24 serve as a medium for transferring heat, and any single region of the surface of the nearby resistor 70 faces both the positive electrode 22 and the negative electrode 24. The heat flowing between the positive electrode 22 and the negative electrode 24 flows through the bonding material 28. As a result, the thermal efficiency for operating the protective element 10 is higher than in the case where any single region of the surface of the near-range resistor 70 faces both the positive electrode 22 and the negative electrode 24.

Further, in the protective element 10 according to the present embodiment, the heat transfer insulating solid 74 contacts the proximity resistor 70 and the low resistance value resistor 72, respectively. The heat transfer insulating solid 74 comes into contact with the positive electrode 22 and the negative electrode 24. As a result, the heat generated by the nearby resistor 70 and the low resistance value resistor 72 is transferred to the positive electrode 22 and the negative electrode 24 via the heat transfer insulating solid 74. Since a solid conducts heat more easily than a gas, the proximity resistor 70 and the low resistance value resistor are compared with the case where there is a space between the positive electrode 22 and the negative electrode 24 and the proximity resistor 70 and the low resistance value resistor 72. The heat generated by 72 easily flows to the positive electrode 22 and the negative electrode 24. The heat flowing between the positive electrode 22 and the negative electrode 24 flows through the bonding material 28. As a result, the thermal efficiency for operating the protective element 10 is higher than in the case where the space between the positive electrode 22 and the negative electrode 24 and the nearby resistor 70 and the low resistance value resistor 72 is provided.

Further, in the protective element 10 according to the present embodiment, the exposed flat surface 90 is exposed in the space in contact with the heating body 40. The positive electrode contact plane 94 contacts the positive electrode side heating body facing plane 50 of the positive electrode 22. The negative electrode contact plane 92 contacts the negative electrode side heating body facing plane 52 of the negative electrode 24. The positive electrode side heating body facing plane 50 and the negative electrode side heating body facing flat surface 52 are possessed by the positive electrode 22 and the negative electrode 24. As a result, the heat generated by the heating body 40 is more likely to be transferred to the positive electrode side heating body facing plane 50 and the negative electrode side heating body facing plane 52 than in the space where the exposed plane 90 is exposed. The exposed plane 90 has a smaller surface area than the convex surface on which it projects toward the exposed space. The exposed plane 90 has a smaller surface area than the concave surface that is recessed when viewed from the exposed space. The small surface area makes it difficult for heat to flow into the space. As a result, the thermal efficiency for operating the protection element 10 is increased.

Further, in the protection element 10 according to the present embodiment, the first lead wire 76 is supported by the first lead support portion 56 of the insulating base 20. The second lead wire 78 is supported by the second lead support portion 58 of the insulating base 20. As a result, compared to the case where the first lead wire 76 and the second lead wire 78 are not supported by the first lead support portion 56 and the second lead support portion 58, the heating body 40, particularly the first lead terminal 36 and the first lead terminal 36 Fatigue fracture between the joint portion of the 1 lead wire 76 and the joint portion of the second lead terminal 38 and the second lead wire 78 is less likely to occur.

Further, in the protective element 10 according to the present embodiment, the tubular support 42 is arranged between the heating body 40 and the second lead support portion 58. The tubular support 42 supports the heating body 40 that receives a force from the compression coil spring 32. As a result, when the bonding strength of the bonding material 28 falls below a predetermined strength, the compression coil spring 32 can sufficiently separate the energizing body 26 from the positive electrode 22 and the negative electrode 24.

<Explanation of modified example>
The protective element 10 described above is exemplified in order to embody the technical idea of the present invention. The protective element 10 described above can be modified in various ways within the scope of the technical idea of the present invention.

For example, the form of the heat transfer insulating solid 74 is not limited to that described above. The surface of the heat transfer insulating solid 74 in contact with the exposed space may protrude toward the space. The surface may be recessed when viewed from the space. The form of the portion where the heat transfer insulating solid 74 contacts the positive electrode 22 and the negative electrode 24 is not limited to a flat surface. The heating body 40 does not have to have the heat transfer insulating solid 74.

Further, the positions of the proximity resistor 70 and the low resistance value resistor 72 are not limited to between the positive electrode 22 and the negative electrode 24. For example, they may face each other with the energizing body 26 in between.

Further, the number of winding resistors included in the heating element 40 is not limited to two, a nearby resistor 70 and a low resistance value resistor 72. The number may be 3 or more. The winding resistors are connected in series. The magnitude of the electrical resistance of these winding resistors is not particularly limited .

Further, the material of the insulating base 20 is not particularly limited. For example, phenol resin can be used as the material. The materials of the positive electrode 22 and the negative electrode 24, which are a pair of electrodes, are not particularly limited. For example, copper or tin-plated brass can be used as the material. The material of the energizing body 26 is also not particularly limited. Further, the forms of the positive electrode 22 and the negative electrode 24 are not limited to those described above.

Further, the material of the bonding material 28 is not particularly limited. Examples of such materials include alloys, pure metals, and conductive adhesives.

Further, instead of providing the lead insulator 30, an insulating film may be formed on the surface of the current-carrying body 26.

Further, the protective element 10 may include another elastic body instead of the compression coil spring 32.

10 ... Protective element 20 ... Insulation base 22 ... Positive electrode 24 ... Negative electrode 26 ... Energizer 28 ... Bonding material 30 ... Lead insulator 32 ... Compression coil spring 34 ... Spring insulator 36 ... First lead terminal 38 ... Second Lead terminal 40 ... Heating body 42 ... Tubular support 44 ... Block-shaped permanent magnet 46 ... Case 50 ... Positive side heating body facing plane 52 ... Negative side heating body facing plane 56 ... First lead support portion 58 ... Second lead support Part 70 ... Near resistance resistor 72 ... Low resistance value resistor 74 ... Insulating solid for heat transfer 76 ... First lead wire 78 ... Second lead wire 80 ... Ceramic plate 90 ... Exposed plane 92 ... Negative negative contact plane 94 ... Positive contact plane 130 ... Intermediate material

Claims (4)

A pair of electrodes arranged to face each other,
An energizing body that is arranged across the pair of electrodes and that allows current to flow between the pair of electrodes.
A bonding material for joining the current-carrying body to each of the pair of electrodes,
An elastic body arranged between the pair of electrodes and applying a separating force to the current-carrying body,
It is provided with a heating body that generates heat transferred to the bonding material.
The separating force is a force in the direction in which the energizing body separates from the pair of electrodes.
The bonding strength of the bonding material falls below a predetermined strength at a predetermined temperature,
The predetermined temperature is the temperature reached by the heat generation of the heating body.
The predetermined strength is a protective element having a strength to withstand the separation force.
The heater has a plurality of winding resistors connected in series with each other.
In a proximity resistor in which one of the plurality of winding resistors is arranged closer to the bonding material than the other winding resistor and the electrical resistance is higher than that of the other winding resistor. protection element you wherein there. The protective element according to claim 1 , wherein the near resistor is arranged between the pair of electrodes. The heating body further has a heat transfer insulating solid that surrounds the plurality of winding resistors, is in contact with each of the plurality of winding resistors, and is in contact with at least one of the pair of electrodes. The protective element according to claim 1. At least one of the pair of electrodes has a heating body facing plane facing the heating body.
The heat transfer insulating solid
The contact plane in contact with the heating body facing plane and
The protective element according to claim 3 , further comprising an exposed flat surface exposed in a space in contact with the heating body.

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