JP2013098134A - Protection element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a protection element which can deal with a larger current than a conventional version.SOLUTION: A protection element 10 comprises a cathode 22, an anode 24, a heat evolution chip 38, a bonding material 40 and a compression coil spring 34. The cathode 22 and the anode 24 face with each other. The heat evolution chip 38 covers both the cathode 22 and the anode 24. The heat evolution chip 38 generates heat when current flows. The bonding material 40 connects the heat evolution chip 38 to the cathode 22 and the anode 24 respectively. Separation force is generated for the heat evolution chip 38 according to the elastic body 34. Bonding strength of the bonding member 40 becomes lower than a prescribed strength at a prescribed temperature. The protection element 10 further comprises a shielding insulation 42 and a magnetic field generation part 50. The shielding insulation 42 is arranged between the cathode 22 and the anode 24 so that the cathode 22 is shielded from the anode 24. The magnetic field generation part 50 generates magnetic force in advance between the cathode 22 and the anode 24.

Description

  The present invention relates to a protective element, and more particularly, to a high-capacity protective element that can appropriately protect a circuit from overcurrent, overcharge, and overdischarge of a secondary battery.

  When using a secondary battery (for example, a lithium ion secondary battery), if any of overcurrent, overcharge, and overdischarge occurs, the secondary battery must be disconnected from the load or charging power source. The

  FIG. 7 shows an example of a known secondary battery protection circuit. The secondary battery protection circuit shown in FIG. 7 includes a load 130, a charging power source 132, a switch 134, a control element 136, and a protection element 138. A known transistor is a kind of element that can be used as the switch 134. The control element 136 detects overcharge or overdischarge of the secondary battery 139. The control element 136 transmits a switch-on signal to the switch 134 when detecting at least one of them. When the switch 134 receives the switch-on signal, the switch 134 is turned on. As a result, a current flows through the switch 134. The protection element 138 cuts off the secondary battery 139 from the load 130 or the charging power source 132 when any of overcurrent, overcharge, and overdischarge occurs.

  FIG. 8 is a perspective view showing a known protection element 138. In FIG. 8, the protection element 138 is shown in an exploded state. The protective element 138 includes an insulating base 20, a positive electrode 22, a negative electrode 24, an electrode fixing member 26, a lead terminal 28, a resistor 30, a resistance insulator 32, a compression coil spring 34, a lead The insulator 36 for heating, the heat generating piece 38, and the case 210 are provided. The insulating base 20 is a member used as a base. The insulating base 20 has heat resistance. The positive electrode 22 is connected to the secondary battery 139 described above. The negative electrode 24 is connected to the load 130 or the charging power source 132 described above. 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 disposed so as to face each other. The electrode fixing material 26 fixes the positive electrode 22 and the negative electrode 24 to the insulating base 20. The electrode fixing material 26 has heat resistance. The lead terminal 28 is connected to a negative lead conductor 60 described later. As a result, a current flows from the lead terminal 28 to the negative lead conductor 60. The lead terminal 28 is connected to the switch 134 described above. The resistor 30 is disposed so as to be sandwiched between the positive electrode 22 and the negative electrode 24. The resistor 30 generates heat when a current flows. Thereby, the resistor 30 serves as a heat source. A negative lead conductor 60 and a positive lead conductor 62 are attached to both ends of the resistor 30. The resistance insulator 32 prevents the compression coil spring 34 from coming into direct contact with the resistor 30. As a result, the compression coil spring 34 and the resistor 30 are insulated. The compression coil spring 34 is disposed at a position that satisfies the following requirements. The first requirement is that it is between the heating piece 38 and the resistor 30. The second requirement is that it is between the positive electrode 22 and the negative electrode 24. The compression coil spring 34 applies a force in a direction away from the positive electrode 22 and the negative electrode 24 to the heating piece 38. For this reason, the compression coil spring 34 is in a compressed state until any of overcurrent, overcharge, and overdischarge occurs. The compression coil spring 34 is made of stainless steel (that is, made of conductor). The positive lead conductor 62 passes through the compression coil spring 34. The lead insulator 36 prevents the positive lead conductor 62 from coming into direct contact with the compression coil spring 34 and the heating piece 38. As a result, the positive lead conductor 62 and the compression coil spring 34 are insulated. The positive lead conductor 62 and the heating piece 38 are also insulated. The positive lead conductor 62 also penetrates the lead insulator 36. The heating piece 38 is disposed across the positive electrode 22 and the negative electrode 24. That is, when the protective element 138 is assembled, the heating piece 38 is bonded to the tip of the positive electrode 22 and the tip of the negative electrode 24. The heating piece 38 is joined to each of the positive electrode 22 and the negative electrode 24 by a low melting point alloy. This low melting point alloy is not shown in FIG. The positive electrode side lead conductor 62 also penetrates the heating piece 38. The positive electrode side lead conductor 62 and the heating piece 38 are joined via a low melting point alloy. This low melting point alloy is also not shown in FIG. The case 210 includes a positive electrode 22, a negative electrode 24, an electrode fixing member 26, a resistor 30, a resistance insulator 32, a compression coil spring 34, a lead insulator 36, a heating piece 38, and a negative electrode side lead. The conductor 60 and the positive electrode side lead conductor 62 are covered.

  When an overcurrent flows through the secondary battery 139, an overcurrent also flows through the heating piece 38 of the protection element 138. When the current flows, the heating piece 38 generates heat. When the heating piece 38 generates heat, the low melting point alloy receives the heat. When subjected to heat, the low melting point alloy reaches a predetermined temperature. The low melting point alloy that has reached the predetermined temperature melts. When the low melting point alloy is melted, the compression coil spring 34 separates the heating piece 38 from the positive electrode 22 and the negative electrode 24. As a result, the load 130 and the secondary battery 139 are disconnected.

  When the secondary battery 139 is in an overdischarged state, the control element 136 transmits a switch-on signal to the switch 134. When the switch 134 receives the switch-on signal, the switch 134 is turned on. When the switch 134 is turned “on”, a current flows through the resistor 30 of the protection element 138. When current flows, the resistor 30 generates heat. When the resistor 30 generates heat, the low melting point alloy receives the heat. When subjected to heat, the low melting point alloy reaches a predetermined temperature. The low melting point alloy that has reached the predetermined temperature melts. When the low melting point alloy is melted, the compression coil spring 34 separates the heating piece 38 from the positive electrode 22 and the negative electrode 24. As a result, the load 130 and the secondary battery 139 are disconnected.

  When the secondary battery 139 is overcharged, the control element 136 transmits a switch-on signal to the switch 134. When the switch 134 receives the switch-on signal, the switch 134 is turned on. When the switch 134 is turned on, the resistor 30 of the protection element 138 generates heat. When the resistor 30 generates heat, the low melting point alloy receives the heat. When subjected to heat, the low melting point alloy reaches a predetermined temperature. The low melting point alloy that has reached the predetermined temperature melts. When the low melting point alloy is melted, the compression coil spring 34 separates the heating piece 38 from the positive electrode 22 and the negative electrode 24. As a result, the charging power source 132 and the secondary battery 139 are disconnected.

  Patent document 1 discloses the invention concerning the protection element 138 mentioned above. The protection element according to Patent Document 1 includes a pair of pin electrodes and a resistor. Lead conductors are attached to both ends of the resistor. The resistors are provided so as to be aligned with the pin electrodes. A heating piece is provided between the pin electrodes. The heating piece spans between the pair of pin electrodes. The heating piece generates heat when energized with overcurrent. One lead conductor of the resistor penetrates the heating piece. Each pin electrode and the heating piece are joined with a low melting point soluble material. One lead conductor of the resistor passes through the compression coil spring between the heating piece and the resistor. The protection element according to Patent Document 1 includes an insulator. The insulator prevents direct contact between the lead conductor and the spring and the heating piece and between the spring and the resistor end face. A resistor energization heating circuit is connected between both lead conductors of the resistor. The resistor energization heating circuit heats the resistor body when the protected device is abnormal. This dissolves the low melting point soluble material.

  In the protection element disclosed in Patent Document 1, current flows mainly directly from one of the pin electrodes to the heating piece. The current mainly flows directly from the heating piece to the other of the pin electrodes. The current flowing through the low melting point soluble material is considerably small. Since the current is small, even if the material of the low melting point soluble material is an alloy, migration of the alloy can be well eliminated. Since migration can be eliminated well, malfunctions based on this can be eliminated. Since malfunctions can be eliminated, overcurrent can be cut off properly.

JP 2009-238719 A

  However, the protection element disclosed in Patent Document 1 has a problem that it is difficult to flow a large current. During operation with a large current flowing, an arc generated inside the protective element may continue immediately after the heating piece is separated from the pin electrode. If the arc persists, the conduction path will be re-formed by the re-conduction caused by the breakage of the compression coil spring opened to maintain the insulation and the burnout of the structure, and the overcurrent cannot be interrupted. Sometimes. The reason why the protective element disclosed in Patent Document 1 is difficult to pass a large current is as described above. The present invention has been made to solve such problems. An object of the present invention is to provide a protective element capable of flowing a larger current than in the past.

  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 elements 10, 12, and 14 include a pair of electrodes 22 and 24, a heating piece 38, a bonding material 40, and an elastic body 34. . The pair of electrodes 22 and 24 are arranged to face each other. The heating piece 38 is disposed across the pair of electrodes 22 and 24. The heating piece 38 generates heat when a current flows. The bonding material 40 bonds the heating piece 38 to each of the pair of electrodes 22 and 24. The elastic body 34 is disposed between the pair of electrodes 22 and 24. The elastic body 34 applies a separating force to the heating piece 38. The separation force is a force in a direction in which the heating piece 38 is separated from the pair of electrodes 22 and 24. The strength of the bonding material 40 is lower than a predetermined strength at a predetermined temperature. The predetermined temperature is a temperature reached by the heat generation of the heating piece 38. The predetermined strength is the strength that can withstand the separation force. The protection elements 10, 12, and 14 further include a shielding insulator 42 and magnetic field generators 50, 52, and 54. The shielding insulator 42 is disposed between the pair of electrodes 22 and 24 so as to shield the other when viewed from one of the pair of electrodes 22 and 24. The magnetic field generators 50, 52, 54 generate a magnetic force in advance between the pair of electrodes 22, 24.

  When an overcurrent flows, the heating piece 38 generates heat. When the bonding material 40 reaches a predetermined temperature due to the heat generated by the heating piece 38, the bonding strength of the bonding material 40 is less than the predetermined strength. When the bonding strength of the bonding material 40 is lower than the predetermined strength, the bonding material 40 cannot withstand the separation force. The heat generating piece 38 is separated from the electrodes 22 and 24 by the elastic body 34 because it cannot withstand the separating force. Thereby, the current between the electrodes 22 and 24 is cut off. When an arc is generated between the electrodes 22 and 24 after the current is cut off, the arc receives a Lorentz force due to the magnetic force generated by the magnetic field generators 50, 52 and 54. The arc is extended by receiving the Lorentz force. Further, when viewed from one of the pair of electrodes 22, 24, the other is blocked by the shielding insulator 42. Since it is blocked by the shielding insulator 42, the arc emitted from one of the pair of electrodes 22 and 24 reaches the other of the electrodes 22 and 24 while avoiding the shielding insulator 42. The arc extends to avoid the shielding insulator 42. When the arc extends due to the Lorentz force and the arc avoiding the shielding insulator 42, the arc voltage increases as compared to the case where the arc does not extend. Moreover, the arc is cooled by being extended. The arc becomes difficult to sustain due to the synergistic effect of the increase in arc voltage and the cooling of the arc. As a result, a large current can be passed.

  Further, it is desirable that the shielding insulator 42 described above has an inter-electrode portion 140 and a protruding portion 142. The inter-electrode portion 140 is disposed so as to be sandwiched between the pair of electrodes 22 and 24. The protruding portion 142 protrudes from the ends of the pair of electrodes 22 and 24 when viewed from the space between the pair of electrodes 22 and 24.

  When the shielding insulator 42 has the inter-electrode portion 140 and the protruding portion 142, an arc between one end and the other end of the electrodes 22, 24 is generated between the inter-electrode portion 140 and the protruding portion 142. It extends compared with the case where at least one is not provided. As the arc extends, the arc voltage rises and the arc becomes difficult to sustain. As a result, a large current can be passed.

  Alternatively, it is desirable that the protrusion 142 described above has a curved surface 150. The curved surface 150 extends from one end 160, 162 of the pair of electrodes 22, 24 to the other end 160, 162. The curved surface 150 protrudes from the ends of the pair of electrodes 22 and 24 when viewed from the space between the pair of electrodes 22 and 24.

  When the following two requirements are satisfied, an arc may be generated along the curved surface 150 between the ends 160 and 162 of the electrodes 22 and 24 that communicate with each other by the curved surface 150. The first requirement is that the curved surface 150 protrudes from the ends of the pair of electrodes 22 and 24. The second requirement is that the curved surface 150 extends from one end 160, 162 of the pair of electrodes 22, 24 to the other end 160, 162. When an arc is generated along the curved surface 150, the arc extends as compared to a case where a straight arc is generated from one end 160, 162 of the electrodes 22, 24 to the other end 160, 162. As the arc extends, the arc voltage rises and the arc becomes difficult to sustain. As a result, a large current can be passed.

  Alternatively, it is desirable that the magnetic field generators 52 and 54 described above have a pair of magnets 70, 72, 74, and 76. In this case, the pair of magnets 70, 72, 74, 76 is arranged so that the N pole and the S pole face each other with the pair of electrodes 22, 24 interposed therebetween.

  When an arc is generated along the curved surface 150, the direction of the arc is at least part of the arc with respect to a direction straight from one end 160, 162 of the electrode 22, 24 to the other end 160, 162. Tilted. Since the direction of the arc generated along the curved surface 150 is so inclined, the arc receives the Lorentz force even if the pair of magnets 70, 72, 74, 76 is opposed to each other with the pair of electrodes 22, 24 interposed therebetween. . The arc extends because it receives Lorentz force. As the arc extends, the arc voltage rises and the arc becomes difficult to sustain. As a result, a large current can be passed.

  Alternatively, it is desirable that one of the pair of magnets 70 and 72 described above has the N-pole surface 100. The N pole surface 100 is disposed from one end of the pair of electrodes 22 and 24 to the other end. In this case, the other of the pair of magnets 70 and 72 has an S pole face 102. The S pole surface 102 is disposed from one end 160, 162 of the pair of electrodes 22, 24 to the other end 160, 162. The S pole face 102 faces the N pole face 100 with the pair of electrodes 22 and 24 interposed therebetween.

  In this case, the direction of the Lorentz force received by the arc based on the magnetic force of the pair of magnets 70 and 72 is constant. By receiving a Lorentz force in a certain direction, the arc can be extended as compared with the case where the direction of the Lorentz force changes. The reason why the arc extends when receiving the Lorentz force in a certain direction as compared with the case where the direction of the Lorentz force is changed is that the arc once receives the Lorentz force when the direction of the Lorentz force changes. As the arc extends, the arc voltage rises and the arc becomes difficult to sustain. As a result, a large current can be passed.

  Moreover, it is desirable that the magnetic field generators 50, 52, 54 described above have permanent magnets 50, 70, 72, 74, 76. When the permanent magnets 50, 70, 72, 74, and 76 are provided, a magnetic force is generated without performing control. Since no control is required, handling becomes easy.

  Moreover, it is desirable that the bonding material 40 described above is a metal. The metal has a melting point at the predetermined temperature described above. When the bonding material 40 is such a metal, the bonding material 40 is melted at a predetermined temperature. Since it melts at a predetermined temperature, the reliability with respect to the heating piece 38 being separated from the pair of electrodes 22 and 24 is higher than the case where a material having a large error with respect to a temperature at which the bonding strength is lower than the predetermined strength is used as the bonding material 40. Become.

  Moreover, it is desirable that the protection elements 10, 12, and 14 described above further include a heat source 30. In this case, the heat source is disposed so as to be sandwiched between the pair of electrodes 22 and 24. In addition to being between the pair of electrodes 22 and 24, the elastic body 34 is disposed at a position between the heating piece 38 and the heat source 30. The temperature at which the bonding material 40 reaches due to heat generated by the heat source 30 is equal to or higher than a predetermined temperature. The shielding insulator 42 has an inter-electrode portion 140. The inter-electrode portion 140 transmits the heat of the heat source 30 to at least one of the pair of electrodes 22 and 24.

  When the interelectrode portion 140 transfers the heat of the heat source 30 to at least one of the electrodes 22 and 24, at least one of the electrodes 22 and 24 transfers the heat to the bonding material 40 compared to the case where the interelectrode portion 140 does not transfer heat. I will tell you. Thereby, compared with the case where the interelectrode part 140 is not provided, the heat which the heat source 30 produced is transmitted well.

  According to the present invention, there is an effect that it is possible to flow a larger current than in the past.

It is a perspective view in the state where a part of protection element concerning a 1st embodiment of the present invention was removed. It is sectional drawing of the protection element concerning 1st Embodiment of this invention. It is an enlarged view of the electrode part of the protection element concerning 1st Embodiment of this invention. It is a conceptual diagram which shows the force which an electron receives in 1st Embodiment of this invention. It is sectional drawing of the protection element concerning 2nd Embodiment of this invention. It is sectional drawing of the protection element concerning 3rd Embodiment of this invention. It is a figure which shows an example of a well-known secondary battery protection circuit. It is a perspective view which shows an example of a well-known protection element.

  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.

<First embodiment>
[Description of configuration]
FIG. 1 is a perspective view of a protection element 10 according to the present embodiment. In FIG. 1, the protection element 10 is shown in an assembled state. In this figure, a part of the protective element 10 is removed. FIG. 2 is a cross-sectional view of the protection element 10 according to the present embodiment. A configuration of the protection element 10 according to the present embodiment will be described with reference to FIGS. 1 and 2.

  The protection element 10 according to the present embodiment includes an insulating base 20, a positive electrode 22, a negative electrode 24, an electrode fixing member 26, a lead terminal 28, a resistor 30, a resistance insulator 32, and a compression coil spring. 34, a lead insulator 36, a heating piece 38, a bonding material 40, a shielding insulator 42, a case 44, and a block-shaped permanent magnet 50.

  In the protective element 10, the insulating base 20, the positive electrode 22, the negative electrode 24, the electrode fixing material 26, the lead terminal 28, the resistor 30, the resistance insulator 32, the compression coil spring 34, the lead insulator 36, and the heating piece Reference numeral 38 denotes the insulating base 20, the positive electrode 22, the negative electrode 24, the electrode fixing member 26, the lead terminal 28, the resistor 30, the resistance insulator 32, the compression coil spring 34, and the lead insulator 36 of the protection element 138 described above. And the same as the heating piece 38. Their arrangement is also the same. Therefore, detailed description thereof will not be repeated here.

  In the present embodiment, the bonding material 40 bonds the heating piece 38 to the positive electrode 22. In the case of this embodiment, another bonding material 40 bonds the heating piece 38 to the negative electrode 24. In the case of the present embodiment, another joining material 40 joins the heating piece 38 to the positive lead conductor 62. The bonding strength of the bonding material 40 is lower than a predetermined strength at a predetermined temperature. In the present embodiment, the “predetermined temperature” is a temperature reached by heat generation of at least one of the heating piece 38 and the resistor 30. In the case of this embodiment, the “predetermined strength” is a strength that can withstand the separation force. In the case of this embodiment, the “separation force” is a force in a direction in which the heating pieces 38 joined to the positive electrode 22 and the negative electrode 24 are 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 34. In the present embodiment, the bonding material 40 is an alloy having the above-described “predetermined temperature” as a melting point.

  In the present embodiment, the shielding insulator 42 is disposed between the positive electrode 22 and the negative electrode 24. Thereby, the other viewed from one of the positive electrode 22 and the negative electrode 24 is blocked by the shielding insulator 42. In the case of this embodiment, the shielding insulator 42 has heat resistance. That is, in the present embodiment, the shielding insulator 42 does not change even when the positive electrode 22, the negative electrode 24, and the resistor 30 generate heat. In the present embodiment, the shielding insulator 42 protects the resistor 30.

  The case 44 includes an insulating base 20, a positive electrode 22, a negative electrode 24, an electrode fixing member 26, a part of a lead terminal 28, a resistor 30, a resistance insulator 32, a compression coil spring 34, The lead insulator 36, the heating piece 38, the bonding material 40, and the shielding insulator 42 are covered. The case 44 is also a part for fixing the block-shaped permanent magnet 50 to a predetermined position. The material of the case 44 is an insulator. The case 44 has a magnet housing portion 80. The block-shaped permanent magnet 50 is accommodated in the magnet accommodating portion 80.

  In the case of the present embodiment, the magnetic field generator is configured only by the block-shaped permanent magnet 50. The block-shaped permanent magnet 50 generates a magnetic force. The space where the magnetic force is generated includes a 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. In the present embodiment, the south pole of the block-shaped permanent magnet 50 faces the positive electrode 22 and the negative electrode 24 with the partition wall 90 therebetween.

  FIG. 3 is an enlarged view of an electrode portion of the protection element 10 according to the present embodiment. The configuration of the shielding insulator 42 according to the present embodiment will be described with reference to FIG. The shielding insulator 42 according to the present embodiment includes an inter-electrode portion 140 and a protruding portion 142.

  The inter-electrode portion 140 is disposed so as to be sandwiched between the positive electrode 22 and the negative electrode 24. When the resistor 30 generates heat, the inter-electrode portion 140 transmits the heat released by the resistor 30 to the positive electrode 22 and the negative electrode 24. Thereby, the joining material 40 is melted by the heat. The protruding portion 142 has a positive electrode end 160 (the positive electrode end 160 is the end of the positive electrode 22) and a negative electrode end 162 (the negative electrode end 162 is the negative electrode 24) as viewed from the space between the positive electrode 22 and the negative electrode 24. It is the end.)

  The protrusion 142 has a curved surface 150. The curved surface 150 extends from the positive electrode end 160 to the negative electrode end 162. The curved surface 150 protrudes from the positive electrode end 160 and the negative electrode end 162 when viewed from the space between the positive electrode 22 and the negative electrode 24.

  The case of this embodiment will be described more specifically. In the case of the present embodiment, the portion of the shielding insulator 42 that is filled between the positive electrode 22 and the negative electrode 24 is the interelectrode portion 140. The inter-electrode portion 140 extends from the electrode fixing member 26 to the resistance insulator 32. A part of the shielding insulator 42 shown in FIG. 3 is removed. Since the portion filled between the positive electrode 22 and the negative electrode 24 in the shielding insulator 42 is the interelectrode portion 140, the resistor 30 is surrounded by the interelectrode portion 140. A part of the shielding insulator 42 protrudes between the positive electrode end 160 and the negative electrode end 162. In the present embodiment, there are two “between the positive electrode end 160 and the negative electrode end 162”. A part of the shielding insulator 42 protrudes from both sides. A part of the protruding shielding insulator 42 is a protruding portion 142. The surface of the protrusion 142 is a curved surface 150. In the case of this embodiment, the shape of the curved surface 150 is the same as the surface of the cylinder.

[Description of usage]
The method of using the protection element 10 according to this embodiment is the same as that of the protection element 138 described above. Therefore, detailed description thereof will not be repeated here.

[Explanation of electronic movement]
FIG. 4 is a conceptual diagram showing the force received by the electrons 120 in this embodiment. For convenience, in FIG. 4, only the positive electrode 22, the negative electrode 24, the resistor 30, the positive electrode side lead conductor 62, the resistance insulator 32, and the block-shaped permanent magnet 50 are shown as components of the protection element 10. With reference to FIG. 4, the movement of the electrons 120 in this embodiment will be described. A large number of electrons 120 are emitted from the negative electrode 24 to form a flow of electrons 120. The flow is an arc. Since the flow of the electrons 120 is an arc, the trajectory of the arc can be explained by explaining the movement of the electrons 120.

  When the bonding material 40 is melted, the compression coil spring 34 is the same as the protection element 138 described above until the heating piece 38 is separated from the positive electrode 22 and the negative electrode 24. At that time, arc discharge from the negative electrode 24 occurs.

  In the present embodiment, the south pole of the block-shaped permanent magnet 50 faces the positive electrode 22, the negative electrode 24, and the shielding insulator 42. Therefore, the direction of the magnetic force 124 is the direction from the positive electrode 22, the negative electrode 24, and the shielding insulator 42 toward the block-shaped permanent magnet 50. In the case of this embodiment, when an arc is generated, electrons 120 are emitted from the negative electrode 24 to the positive electrode 22. When the electrons 120 are emitted, the electrons 120 pass on the curved surface 150. The reason why the electrons 120 pass on the curved surface 150 is that when dielectric breakdown occurs, a path for the electrons 120 is formed there. The traveling direction of the electrons 120 is a tangential direction of the curved surface 150. The direction of the current 122 is opposite to the traveling direction of the electrons 120. The current 122 can be decomposed into a component 180 orthogonal to the magnetic force 124 and other components. Since the electron 120 moves in the magnetic field, the Lorentz force 126 acts on the electron 120. In the case of this embodiment, the direction of the Lorentz force 126 is downward in FIG. Thereby, the trajectory drawn by the electron 120 is bent. Since the trajectory drawn by the electrons 120 bends, the arc trajectory also bends.

[Description of effects]
As described above, in the protection element 10 according to the present embodiment, the arc trajectory is bent. When the trajectory is bent, the arc extends as compared to the case where the trajectory is not bent. When the arc extends, the voltage (arc voltage) at which the arc is generated becomes higher than when the arc does not extend. The arc is extended and cooled by contacting a structure made of an insulating material (in this embodiment, the case 44 corresponds to a “structure made of an insulating material”). The arc becomes difficult to sustain due to the synergistic effect of the increase of the arc voltage and the cooling of the arc. Since it becomes difficult for the arc to be sustained, a larger current can be passed as compared with the case where the arc is likely to occur. As a result, the protection element 10 according to the present embodiment can pass a larger current than the conventional one.

<Second Embodiment>
[Description of configuration]
FIG. 5 is a cross-sectional view of the protection element 12 according to the present embodiment. The configuration of the protection element 12 according to the present embodiment will be described with reference to FIG. The protection element 12 according to the present embodiment includes an insulating base 20, a positive electrode 22, a negative electrode 24, an electrode fixing member 26, a lead terminal 28, a resistor 30, a resistance insulator 32, and a compression coil spring. 34, a lead insulator 36, a heating piece 38, a bonding material 40, a shielding insulator 42, a case 46, and a magnetic field generator 52.

  In the protective element 12, the insulating base 20, the positive electrode 22, the negative electrode 24, the electrode fixing material 26, the lead terminal 28, the resistor 30, the resistance insulator 32, the compression coil spring 34, the lead insulator 36, and the heating piece Reference numeral 38 denotes the insulating base 20, the positive electrode 22, the negative electrode 24, the electrode fixing member 26, the lead terminal 28, the resistor 30, the resistance insulator 32, the compression coil spring 34, and the lead insulator 36 of the protection element 138 described above. And the same as the heating piece 38. Their arrangement is also the same. In the protection element 12, the bonding material 40 and the shielding insulator 42 are the same as the bonding material 40 and the shielding insulator 42 according to the first embodiment. Their arrangement is also the same. Therefore, detailed description thereof will not be repeated here.

  Similar to the cases 210 and 44 described above, the case 46 includes the insulating base 20, the positive electrode 22, the negative electrode 24, the electrode fixing material 26, a part of the lead terminal 28, the resistor 30, and the resistance. The insulating insulator 32, the compression coil spring 34, the lead insulator 36, the heat generating piece 38, the bonding material 40, and the shielding insulator 42 are covered. The case 46 is also a component for fixing the magnetic field generator 52 at a predetermined position. The material of the case 46 is an insulator. The case 46 has a first magnet housing portion 82 and a second magnet housing portion 84. These are arranged so as to face each other with a space between the positive electrode 22 and the negative electrode 24 interposed therebetween.

  The magnetic field generator 52 generates a magnetic force between the positive electrode 22 and the negative electrode 24. In the case of the present embodiment, the magnetic field generator 52 has a pair of magnets. One of those magnets is a first plate-like permanent magnet 70. The other of these magnets is a second plate-like permanent magnet 72. In the case of this embodiment, the 1st plate-shaped permanent magnet 70 and the 2nd plate-shaped permanent magnet 72 have the same magnetic force as the block-shaped permanent magnet 50 concerning 1st Embodiment. The first plate-like permanent magnet 70 is housed in the first magnet housing portion 82 of the case 46. The second plate-like permanent magnet 72 is housed in the second magnet housing portion 84 of the case 46. As described above, the first magnet housing portion 82 and the second magnet housing portion 84 are disposed so as to face each other with the space between the positive electrode 22 and the negative electrode 24 interposed therebetween. Thereby, the pair of magnets included in the magnetic field generation unit 52 is also arranged so as to face each other with the space between the positive electrode 22 and the negative electrode 24 interposed therebetween.

  The first plate-like permanent magnet 70 has an S pole surface 102. The second plate-shaped permanent magnet 72 has an N pole surface 100. The N pole surface 100 is the N pole of the second plate-like permanent magnet 72. The N pole surface 100 faces the space between the positive electrode 22 and the negative electrode 24. However, a partition wall 94 is provided between the space and the N pole surface 100. The partition wall 94 constitutes the second magnet housing portion 84. The N pole surface 100 extends from one of the positive electrode 22 and the negative electrode 24 to the other. The S pole surface 102 is the S pole of the first plate-like permanent magnet 70. The S pole surface 102 is also opposed to the space between the positive electrode 22 and the negative electrode 24. However, a partition wall 92 is also provided between the space and the S pole surface 102. The partition 92 constitutes a first magnet housing part 82. The S pole surface 102 also extends from one of the positive electrode 22 and the negative electrode 24 to the other.

  As described above, the pair of magnets included in the magnetic field generation unit 52 is disposed so as to face each other with the space between the positive electrode 22 and the negative electrode 24 interposed therebetween. Both the N pole face 100 and the S pole face 102 face the space. Thereby, the pair of the first plate-like permanent magnet 70 and the second plate-like permanent magnet 72 is arranged so that the N pole and the S pole face each other across the space between the positive electrode 22 and the negative electrode 24. It becomes.

[Description of usage]
The method of using the protection element 12 according to this embodiment is the same as that of the protection element 138 and the protection element 10 described above. Therefore, detailed description thereof will not be repeated here.

[Explanation of electronic movement]
The movement of the electrons 120 according to the present embodiment is the same as that of the protection element 10 according to the first embodiment. However, in the case of the present embodiment, the pair of the first plate-like permanent magnet 70 and the second plate-like permanent magnet 72 is such that the N pole and the S pole face each other across the space between the positive electrode 22 and the negative electrode 24. Are arranged as follows. Comparing the strength of the magnetic force at the same location in the space between the positive electrode 22 and the negative electrode 24, the magnetic force of the magnetic field generator 52 according to the present embodiment is the same as that of the first embodiment (block permanent magnet 50). It is more than the magnetic force. This is the same even if the block-shaped permanent magnet 50 is slightly stronger than the first plate-shaped permanent magnet 70 and the second plate-shaped permanent magnet 72. Since the magnetic force is strong, if an arc is generated in the protection element 12 according to the present embodiment, the arc extends better than the arc that should be generated in the protection element 10 according to the first embodiment. Moreover, in this embodiment, the direction of the Lorentz force that the arc receives based on the magnetic force of the pair of the first plate-like permanent magnet 70 and the second plate-like permanent magnet 72 is constant. By receiving a Lorentz force in a certain direction, the arc can be extended as compared with the case where the direction of the Lorentz force changes. The reason why the arc extends when receiving the Lorentz force in a certain direction as compared with the case where the direction of the Lorentz force is changed is that the arc once receives the Lorentz force when the direction of the Lorentz force changes.

[Description of effects]
As described above, the arc extends well in the protection element 12 according to the present embodiment. Since the arc extends well, the arc can be made difficult to sustain by the synergistic effect of the increase in arc voltage and the cooling of the arc. As a result, the protection element 12 according to the present embodiment can pass a larger current than in the past.

  Moreover, in the protection element 12 according to the present embodiment, a larger magnetic force is generated from the positive electrode 22 to the negative electrode 24 than when a magnetic force is generated by a single magnet. As the magnetic force increases, the Lorentz force received by the arc increases. When the Lorentz force increases from the positive electrode 22 to the negative electrode 24, the arc is less likely to be sustained than in the case where the Lorentz force is large in a part of the space from the positive electrode 22 to the negative electrode 24. As a result, a large current can be passed.

  In addition, the protection element 12 according to the present embodiment has a higher arc resistance than the case where the direction of the Lorentz force received by the arc changes based on the magnetic force of the pair of the first plate-like permanent magnet 70 and the second plate-like permanent magnet 72. Can be extended. As a result, the protection element 12 according to the present embodiment can pass a larger current than in the past.

<Third embodiment>
[Description of configuration]
FIG. 6 is a cross-sectional view of the protection element 14 according to the present embodiment. The configuration of the protection element 14 according to the present embodiment will be described with reference to FIG. The protection element 14 according to the present embodiment includes an insulating base 20, a positive electrode 22, a negative electrode 24, an electrode fixing member 26, a lead terminal 28, a resistor 30, a resistance insulator 32, and a compression coil spring. 34, a lead insulator 36, a heating piece 38, a bonding material 40, a shielding insulator 42, a case 48, and a magnetic field generator 54.

  In the protection element 14, the insulating base 20, the positive electrode 22, the negative electrode 24, the electrode fixing material 26, the lead terminal 28, the resistor 30, the resistance insulator 32, the compression coil spring 34, the lead insulator 36, and the heating piece Reference numeral 38 denotes the insulating base 20, the positive electrode 22, the negative electrode 24, the electrode fixing member 26, the lead terminal 28, the resistor 30, the resistance insulator 32, the compression coil spring 34, and the lead insulator 36 of the protection element 138 described above. And the same as the heating piece 38. Their arrangement is also the same. In the protection element 14, the bonding material 40 and the shielding insulator 42 are the same as the bonding material 40 and the shielding insulator 42 according to the first embodiment. Their arrangement is also the same. Therefore, detailed description thereof will not be repeated here.

  The case 48 is similar to the case 210, the case 44, and the case 46 described above, the insulating base 20, the positive electrode 22, the negative electrode 24, the electrode fixing member 26, a part of the lead terminal 28, and the resistance. The container 30, the resistance insulator 32, the compression coil spring 34, the lead insulator 36, the heating piece 38, the bonding material 40, and the shielding insulator 42 are covered. The case 48 is also a component for fixing the magnetic field generator 54 at a predetermined position. The material of the case 48 is an insulator. The case 48 has a first magnet housing portion 86 and a second magnet housing portion 88. These are arranged to face each other with the positive electrode 22 and the negative electrode 24 interposed therebetween.

  The magnetic field generator 54 generates a magnetic force between the positive electrode 22 and the negative electrode 24. In the case of this embodiment, the magnetic field generator 54 has a pair of magnets. One of those magnets is a first plate-like permanent magnet 76. The other of these magnets is a second plate-like permanent magnet 74. In the case of this embodiment, the 1st plate-shaped permanent magnet 76 and the 2nd plate-shaped permanent magnet 74 have the same magnetic force as the block-shaped permanent magnet 50 concerning 1st Embodiment. The first plate-like permanent magnet 76 is housed in the first magnet housing portion 86 of the case 48. The second plate-shaped permanent magnet 74 is housed in the second magnet housing portion 88 of the case 48. As described above, the first magnet housing portion 86 and the second magnet housing portion 88 are disposed so as to face each other with the positive electrode 22 and the negative electrode 24 interposed therebetween.

  The first plate-shaped permanent magnet 76 has an S pole surface 106. The second plate-shaped permanent magnet 74 has an N pole surface 104. The N pole surface 104 is the N pole of the second plate-like permanent magnet 74. The N pole surface 104 faces the negative electrode 24. However, a partition wall 96 is provided between the negative electrode 24 and the N pole surface 104. The partition wall 96 constitutes the second magnet housing portion 88. As is clear from FIG. 6, the N pole surface 104 extends from one end of the negative electrode 24 to the other end. That is, the range of the N pole surface 104 extends from one end of the negative electrode 24 to the other end. The S pole surface 106 is the S pole of the first plate-like permanent magnet 76. The S pole surface 106 faces the positive electrode 22. A partition wall 98 is provided between the positive electrode 22 and the S pole surface 102. The partition wall 98 forms a first magnet housing portion 86. The S pole surface 106 also extends from one end of the positive electrode 22 to the other end.

  As is clear from FIG. 6 and the above description, the pair of magnets included in the magnetic field generation unit 54 is disposed so as to face each other with the positive electrode 22 and the negative electrode 24 interposed therebetween. Thereby, the pair of the first plate-like permanent magnet 76 and the second plate-like permanent magnet 74 is arranged so that the N pole and the S pole face each other across the space between the positive electrode 22 and the negative electrode 24. It becomes.

[Description of usage]
The usage method of the protection element 14 according to the present embodiment is the same as that of the protection element 138, the protection element 10, and the protection element 12 described above. Therefore, detailed description thereof will not be repeated here.

[Explanation of electronic movement]
In the case of this embodiment, the N pole surface 104 faces the negative electrode 24. The S pole surface 106 faces the positive electrode 22. Therefore, the direction of the magnetic force between the positive electrode 22 and the negative electrode 24 is the direction from the left side to the right side in FIG. In the case of this embodiment, when an arc is generated, electrons are emitted from the negative electrode 24 to the positive electrode 22. When electrons are emitted, they pass on the curved surface 150. The traveling direction of electrons is the tangential direction of the curved surface 150. The direction of the current is opposite to the traveling direction of the electrons. The current can be decomposed into a component orthogonal to the magnetic force and other components. The direction of the component orthogonal to the magnetic force changes while the electrons travel on the curved surface 150. The direction of the component orthogonal to the magnetic force immediately after being discharged from the negative electrode 24 is opposite to the direction of the component orthogonal to the magnetic force immediately before reaching the positive electrode 22. Since electrons move in the magnetic field, Lorentz force acts on the electrons. As described above, since the direction of the component of the current orthogonal to the magnetic force changes, the direction of the Lorentz force also changes. Although the orientation changes, the Lorenz force acts on the electrons and the trajectory drawn by the electrons bends. Since the trajectory drawn by the electron bends, the trajectory of the arc also bends.

  However, in the case of the present embodiment, the pair of magnets included in the magnetic field generation unit 54 is disposed so as to face each other with the positive electrode 22 and the negative electrode 24 interposed therebetween. Comparing the strength of the magnetic force at the same location in the space between the positive electrode 22 and the negative electrode 24, the magnetic force of the magnetic field generator 54 according to the present embodiment is a single magnet (the first plate-like permanent magnet 76 or the second plate). The same as that of the permanent magnet 74). Since the magnetic force is strong, if an arc is generated in the protection element 14 according to the present embodiment, the arc extends better than the arc that should be generated when the single magnet described above is used.

[Description of effects]
As described above, in the protection element 14 according to the present embodiment, the arc extends well. Since the arc extends well, the arc can be made difficult to sustain by the synergistic effect of the increase in arc voltage and the cooling of the arc. As a result, the protection element 14 according to the present embodiment can pass a larger current than in the past.

<Description of modification>
The above-described protective elements 10, 12, and 14 are illustrated in order to embody the technical idea of the present invention. The protection elements 10, 12, and 14 described above can be modified in various ways within the scope of the technical idea of the present invention.

  For example, the number and arrangement of magnets are not limited to those described above. The element for generating a magnetic field, that is, a magnet is not limited to a permanent magnet. An example of a magnet other than a permanent magnet is an electromagnet. Moreover, the kind of permanent magnet is not specifically limited. Examples of types of permanent magnets include samarium cobalt magnets, neodymium magnets, ferrite magnets, and alnico magnets.

  Further, the cases 46 and 48 described above may be used as parts for contacting the arc when the arc is extended by the Lorentz force, similarly to the case 44 according to the first embodiment. For this purpose, the cases 46 and 48 may be arranged so that the arc extended by the Lorentz force contacts the cases 46 and 48. The cases 46 and 48 described above are insulators and are solid. In general, solids have a higher thermal conductivity than gases. Since the heat conductivity is high, the arc and its surroundings can be efficiently cooled by bringing the arcs into contact with the cases 46 and 48 as compared with the case of cooling by the space.

  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 that are a pair of electrodes are not particularly limited. For example, copper and tin-plated brass can be used as the material. The material of the electrode fixing material 26 is not particularly limited. The material of the heating piece 38 is not particularly limited. The structure of the resistor 30 is not particularly limited. For example, the resistor 30 includes a winding type (a negative electrode to which a negative lead conductor 60 is attached and a positive electrode to which a positive lead conductor 62 is attached at both ends of a ceramic score, and a resistance wire is wound around the ceramic score. The resistance wire may have both ends bonded to the positive electrode and the negative electrode) or a metal oxide film type (a metal oxide film formed on the core). The protection elements 10, 12, and 14 may include a different type of heat source from the resistor 30. However, the heat source needs to make the bonding material 40 reach a temperature equal to or higher than its melting point. The protection elements 10, 12, and 14 may not include a heat source that replaces the resistor 30.

  Further, the material of the bonding material 40 is not particularly limited. Examples of the material include a pure metal, a thermoplastic resin, and a conductive adhesive in addition to an alloy.

  Further, instead of providing the lead insulator 36, an insulating film may be formed on the surface of the heating piece 38.

  The protection elements 10, 12, and 14 may include another elastic body instead of the compression coil spring 34.

  Further, the protruding portion 142 may be provided only at one end of the inter-electrode portion 140.

10, 12, 14, 138 Protective element 20 Insulating base 22 Positive electrode 24 Negative electrode 26 Electrode fixing material 28 Lead terminal 30 Resistor 32 Resistor insulator 34 Compression coil spring 36 Lead insulator 38 Heating piece 40 Bonding material 42 For shielding Insulators 44, 46, 48, 210 Case 50 Block-shaped permanent magnets 52, 54 Magnetic field generator 60 Negative-side lead conductor 62 Positive-side lead conductors 70, 76 First plate-shaped permanent magnets 72, 74 Second plate-shaped permanent magnet 80 Magnet housing part 82, 86 First magnet housing part 84, 88 Second magnet housing part 90, 92, 94, 96, 98 Bulkhead 100, 104 N pole face 102, 106 S pole face 120 Electronics 130 Load 132 Charging power supply 134 Switch 136 Control element 139 Secondary battery 140 Interelectrode portion 142 Projection portion 150 Curved surface 160 Positive electrode end 162 Negative electrode end 180 Component

Claims (8)

A pair of electrodes arranged to face each other;
A heating piece disposed between the pair of electrodes and generating heat when a current flows;
A bonding material for bonding the heating piece to each of the pair of electrodes;
An elastic body disposed between the pair of electrodes and applying a separating force to the heating piece,
The separation force is a force in a direction in which the heating piece is separated from the pair of electrodes,
The bonding strength of the bonding material is lower than a predetermined strength at a predetermined temperature,
The predetermined temperature is a temperature reached by heat generation of the heating piece,
The predetermined strength is a protective element that is strong enough to withstand the separation force,
A shielding insulator disposed between the pair of electrodes so as to shield the other when viewed from one of the pair of electrodes;
A protective element, further comprising: a magnetic field generator that generates a magnetic force in advance between the pair of electrodes. The shielding insulator comprises:
An inter-electrode portion disposed so as to be sandwiched between the pair of electrodes;
The protective element according to claim 1, further comprising: a protruding portion protruding from an end of the pair of electrodes when viewed from a space between the pair of electrodes.   The protruding portion has a curved surface that extends from one end of the pair of electrodes to the other end and protrudes from the ends of the pair of electrodes when viewed from the space between the pair of electrodes. The protective element according to claim 2.   The protection element according to claim 3, wherein the magnetic field generation unit includes a pair of magnets arranged so that an N pole and an S pole face each other across the pair of electrodes. One of the pair of magnets has an N-pole surface arranged from one end to the other end of the pair of electrodes,
The other of the pair of magnets is disposed from one end to the other end of the pair of electrodes, and has an S pole face that faces the N pole face across the pair of electrodes. The protective element according to claim 4.   The protective element according to claim 1, wherein the magnetic field generation unit includes a permanent magnet.   The protective element according to claim 1, wherein the bonding material is a metal having a melting point at the predetermined temperature. The protective element further comprises a heat source disposed so as to be sandwiched between the pair of electrodes,
In addition to being between the pair of electrodes, the elastic body is disposed at a position between the heating piece and the heat source,
The temperature at which the bonding material reaches due to the heat generated by the heat source is equal to or higher than the predetermined temperature, the shielding insulator is disposed between the pair of electrodes, and at least the pair of electrodes The protective element according to claim 1, further comprising an inter-electrode portion that transfers heat from the heat source.

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