JP6146764B2 - Temperature protection element - Google Patents

Description

  The present invention relates to a temperature protection element that opens and closes an electric circuit by using a thermal responder typified by a bimetal and a PTC element, and more particularly to a temperature protection element that can reduce the thickness of a product and can cope with a large current even in a small size.

  2. Description of the Related Art A protective element using a bimetal and a PTC element in combination is conventionally used in a power supply circuit protective device including a secondary battery. For example, the safety device described in Patent Document 1 is a base terminal, PTC, bimetal, a movable arm connected to an arm terminal, and a safety device built in a resin case in which a cover terminal is composed of a base and a cover. ing. By integrating the cover terminal of the safety device with the cover of the resin case, the space between the cover of the resin case and the movable arm can be made as narrow as possible. The cover of the resin case and the cover terminal may be separate parts, but it is preferable that the cover of the resin case and the cover terminal are integrated by insert molding. The built-in cover terminal helps cut off the current even when the movable arm has a small movement width, and also narrows the space with the cover of the resin case to make the safety device smaller and thinner.

  Further, Patent Document 2 has a structure in which one end of a conductive arm, one end of a bimetal, and a terminal of a case body are welded and integrated, and the bimetal is not only reversed by the temperature rise of the surrounding atmosphere, When the heat generated in the conductive arm and the terminal induced by the current flowing in the conductive arm and the terminal is efficiently received and an overload is applied to the elements in the circuit and the amount of current increases, the temperature of the bimetal increases. A protector has been proposed that speeds up the reversing operation by quickly rising and transitioning from the non-reversing state to the reversing state.

  However, in the safety device described in Patent Document 1, since the opening of the resin case is covered and sealed with a resin cover including a cover terminal, the cap-shaped resin cover has an intermediate restraint and stopper irregularities. Even if the terminals are integrally molded so as to be advantageous in reducing the thickness, there is a limit to the reduction in the height of the insert molded product, and it has been difficult to further reduce the thickness of the product. In addition, when the resin case is covered and sealed only with the resin cover, there is a limit to reducing the thickness of the resin in order to secure the sealing package strength. Furthermore, because the surface of the cover material covering the resin case and its opening is covered with resin, the thermal conductivity and heat dissipation of the package are poor, and the rapid thermal response during overheating and the external temperature are reduced. When the quick return operation was hindered.

  By the way, like the protector described in Patent Document 2, the circuit protection element using the conventional bimetal and PTC is not only reversed by the increase of the ambient temperature, but also by the current flowing through the conductive arm and the terminal. Overcurrent operation using Joule heat was also considered at the same time. However, as long as such a configuration is adopted, there is a drawback that a protection element using a combination of bimetal and PTC cannot be used for protecting a power supply circuit having a large current rating. And also in the structure of this patent document 2, the base of a case body and its cover are comprised with the insulating material, and it is inferior to the heat conductivity and heat dissipation of a package like the structure of patent document 1, and quick thermal response at the time of overheating Moreover, it is disadvantageous because it prevents a quick return operation when the external temperature decreases.

JP 2005-203277 A JP 2006-269180 A

  Therefore, according to the present invention, in the temperature protection element that opens and closes the electric circuit by using the thermal responder and the PTC element in combination, the thickness of the product can be reduced, and the thermal conductivity and heat dissipation of the package are improved to improve the temperature sensitivity. However, it is an object of the present invention to provide a temperature protection element that saves power and is small in size and can handle a large current.

According to the present invention, in order to solve the above-described problems, the first terminal lead provided with the fixed contact, the movable arm provided with the movable contact provided at one end by the elastic force, and the movable arm are contacted. A second terminal lead, a thermally actuated body that always contacts the movable arm and snaps in reverse at a predetermined temperature to disconnect the fixed contact and the movable contact; and the thermal responder and the first terminal lead A PTC element to be energized, an insulating package provided with an opening for storing these, and a metal thin plate covering the opening of the insulating package; and the insulating package includes both the terminal leads formed integrally, A fixed contact, movable arm, thermal responder, and PTC element are housed inside the package, the package opening is covered with a thin metal plate, and the insulation package is fixedly sealed with a sealing resin provided on the outer edge of the thin metal plate. Temperature protection device is provided. Furthermore, the first and second terminal leads and the movable arm of the temperature protection element according to the invention are characterized by using a highly conductive metal material having a conductivity% IACS of 25 or more. Here, IACS is an international annealed copper standard (International Annealed Copper Standard) that has been adopted internationally as a standard for electrical resistance when examining the electrical conductivity of copper materials, and the volume resistivity of the international annealed soft copper standard. 1.7241 × 10 ⁻² μΩm is defined as 100% conductivity IACS.

  Since the temperature protection element according to the present invention seals the opening of the package with a thin metal plate, the insulation package can be made smaller and thinner. In addition, since the insulating package and the metal thin plate are fixedly sealed by applying a sealing resin only to the outer edge portion of the metal thin plate, the metal thin plate can be exposed to the surface, and heat conduction to the thermal actuator and the PTC element incorporated in the package Contribute to. In addition, unlike conventional safety devices, there is no need to insert-molded or individually assembled cover terminals that have been previously bent into a cap-shaped resin cover, and the resin cover member can be omitted, resulting in more economical production. Is possible. Furthermore, the temperature protection element according to the invention can save more power by using a highly conductive metal material having a conductivity% IACS of 25 or more for the terminal lead, and can reduce the internal resistance value of the protection element while being small in size. It is possible to prevent malfunction due to inrush current when the switch is ON, and to apply to a power source having a relatively large steady current.

FIG. 2 is a temperature protection element 10 according to the present invention, in which (a) is an exploded perspective view of its component members, (b) is a plan perspective view after assembly completion, and (c) is a bottom perspective view after assembly completion. The figure is shown. The perspective view of the movable arm of the temperature protection element which concerns on this invention is shown, (a) is the movable arm which bent the front-end | tip part of one side into the concave shape, and provided the movable contact in the lower side, (b) is the modification, and shows one side. A movable arm which is bent at the tip to provide a movable contact on the lower side, and further has a notch in the tip to make the movable contact bifurcated. (C) is another modified example with a step and a depression at one tip. And a movable arm provided with a movable contact on the lower side. The temperature protection element 30 which concerns on this invention is shown, (a) is the front sectional drawing, (b) shows the front sectional drawing after the operation | movement. The temperature protection element 40 which concerns on this invention is shown, (a) is the front sectional drawing, (b) shows the front sectional drawing after the operation | movement.

  The embodiment of the present invention includes a first terminal lead 11 made of Cu or Cu alloy provided with a fixed contact 11-1 made of Ag or an Ag alloy, and Ag or Ag at one end, like the temperature protection element 10 shown in FIG. A movable arm 12 made of a Cu alloy provided with a movable contact 12-1 made of Ag alloy and brought into contact with the fixed contact 11-1 by a resilient force, and a second terminal lead made of Cu or Cu alloy electrically connected to the movable arm 12 13, a thermally actuated body 14 made of a bimetallic material that always contacts the movable arm 12 and snap-inverts at a predetermined temperature to separate the fixed contact 11-1 and the movable contact 12-1, and the thermally actuated body 14. And a positive temperature coefficient thermistor PTC element 15 that is connected to the first terminal lead 11 and energized, and is formed integrally with the terminal leads 11 and 13 and provided with an opening. The movable arm 12, the thermally actuated body 14, and the PTC element 15 are accommodated in the insulating package 16 made of a metal, and the opening of the insulating package 16 is covered only with the thin metal plate 17 having excellent thermal conductivity and heat dissipation. The insulating package 16 is fixedly sealed with a sealing resin 18 provided on the outer edge of the thin plate 17.

  Further, preferably, as shown in FIG. 1C, the bottom portion of the insulating package 16 may expose a portion 11-4 of the first terminal lead to improve the heat conduction to the inside of the insulating package 16. The first terminal lead 11 and the second terminal lead 13 of the temperature protection element 10 and the movable arm 12 are made of a highly conductive metal material having a conductivity% IACS of 25 or more, more preferably a Cu—Sn alloy material, Cu Using at least one alloy material selected from the group consisting of a Ti alloy material and a Cu—Be alloy material, a desired elastic repulsion force is provided while maintaining high conductivity.

  The PTC element 15 according to the present invention may be a positive temperature coefficient thermistor, and a ceramic PTC element preferably made of an oxide semiconductor can be used. Then, by using the first and second terminal leads and the movable arm made of a highly conductive metal material having a conductivity% IACS of 25 or more, the electric resistance value of both the terminal leads and the movable arm itself is reduced, whereby the PTC element 15 The electrode material applied to is simplified to only ohmic electrodes. That is, the surface electrode of the PTC element 15 is composed only of an ohmic electrode provided on the element, and is conventionally a cover electrode made of a noble metal good conductor layer such as Ag applied to the outermost surface of the electrode material of the PTC element. Is omitted. The ohmic electrode of the PTC element 15 according to the present invention includes, for example, Al material, Cr material, Ni material, Ni—Cr alloy material, Ag—In alloy material, Ag—Zn alloy material, Ag—Sb alloy material, Ag—Zn—. A metal material such as an Sb alloy material can be used, and in particular, an Al material or an Ag—Zn alloy material can be suitably used. In this case, since the PTC element 19 does not require the noble metal electrode material of the cover electrode, the essential material can be reduced and the manufacturing cost can be reduced.

  The PTC element 15 according to the present invention includes a conductive polymer (including a crystalline organic polymer having a positive temperature coefficient resistance value) instead of the above-described ceramic PTC element made of an oxide semiconductor. Polymer PTC elements made of dispersed or dispersed fine particle fillers may be used. By using the polymer PTC element, the thickness of the insulating package 16 is further reduced.

  The tip shape of the movable arm 12 according to the present invention may be modified as shown in FIG. That is, the movable arm 12 shown in FIG. 2 (a) is bent at an obtuse angle at the arm bending point 12-4, and the tip is processed into a U-shape or V-shape, thereby increasing the spring pressure of the movable contact 12-1. As shown in FIG. 2B, the contact range of the movable contact 12-1 that can be connected to the horizontal plane of the fixed contact is expanded to ensure the electrical connection of the movable contact 12-1 to the fixed contact. Further, the distal end portion can be processed into a U-shape or V-shape, and further, the movable arm 22 can be deformed by forming a plurality of independent movable contacts 22-1 by providing notches 22-5 at the distal end portion. This improves the contact reliability of the fixed contacts by correcting the unevenness of the fixed contacts caused by the left and right differentials and the local wear. Furthermore, the movable arm 12 can be transformed into a movable arm 52 as shown in FIG. The movable arm 52 is provided with a step 52-5 and a depression 52-6 at the end of the movable arm, and the lower surface of the distal end of the movable arm is processed into a convex shape, so that the movable contact 52 is similar to FIG. -1 is increased, the contact range of the movable contact 52-1 that can be connected to the horizontal surface of the fixed contact is expanded, and the effect of ensuring the electrical connection of the movable contact 52-1 to the fixed contact is obtained. Can do. Ag or an Ag alloy is fixed to the surface of the convex portion on the lower surface of the distal end portion of the movable arm to form a movable contact 52-1. The other end of the movable arm 52 may be provided with a notch 52-7 for the purpose of helping to attach the movable arm 52 to a predetermined position of the insulating package. In addition, 12-2, 12-3, 22-2, 22-3 and 52-2, 52-3 in FIG. 2 show the positions of the connection protrusions provided on the lower surface.

  Example 1 of the present invention is a Cu-Sn alloy first terminal lead 31 provided with a fixed contact 31-1 of Ag-Cu clad material and an element connection electrode 31-2, as in the temperature protection element 30 shown in FIG. A Cu-Sn alloy movable arm 32 provided with a movable contact 32-1 made of an Ag-Cu clad material at the tip, and a Cu-Sn alloy second product provided with an arm connection electrode 33-1 in contact with the movable arm 32. A terminal lead 33, a thermally actuated body 34 made of a bimetallic material of Ni-Fe alloy / Cu-Mn-Ni alloy and separating the fixed contact 31-1 and the movable contact 32-1, and the thermally actuated body 34 and the element A barium titanate-based oxide semiconductor PTC element 35 connected to the connection electrode 31-2 and energized, a liquid crystal polymer insulating package 36 provided with an opening for accommodating these, and an opening of the insulating package 36 are covered. The insulating package 36 is integrally formed with both the terminal leads 31 and 33 by insert molding, and the movable arm 32, the thermal actuator 34, and the PTC element 35 are accommodated inside the package. Then, the package opening is covered with a thin metal plate 37 and fixed to the insulating package 36 with a UV curable resin 38 applied along the outer edge of the thin metal plate 37 and sealed.

  Although not particularly illustrated, the temperature protection element 30 according to the first embodiment can be modified so that the built-in thermal responder 34 and the PTC element 35 are installed without being connected to an electric circuit. That is, in the modified example of the temperature protection element 30, the thermal responder 34 is disposed separately from the movable arm 32 in the initial state, detects overheating, separates the fixed contact 31-1 and the movable contact 32-1, and reverses it. The PTC element 35 that comes into contact with the movable arm 32 when it is operated and simultaneously contacts the thermal responder 34 can be deformed so as to be connected to the thermal responder 34 and the element connection electrode 31-2 and to be energized.

  In the insulating package 36 of the first embodiment, the opening is covered with a thin metal plate 37, and the first terminal lead 31 extending inside the insulating package 36 is exposed at the bottom of the insulating package 36. By forming the lead exposed surface 31-4, the heat conduction of the insulating package 36 is improved and the temperature sensitivity is further enhanced. The insulating package 36 is provided with a bank-shaped peripheral wall 39 along the periphery of the opening to assist the positioning of the thin metal plate 37 and to form a guide portion for the dispenser needle of the UV curable resin 38 to apply the liquid resin. In addition, an application margin having an L-shaped cross section is formed between the inner surface of the peripheral wall and the upper surface of the outer edge of the metal thin plate 37, and resin sagging is prevented by the interfacial tension between the application margin and the sealing resin.

  The surface electrode 35-1 applied to the PTC element 35 of Example 1 is composed of only an ohmic electrode made of an Ag—Zn alloy material, and the surface electrode on the PTC element 35 is in contact with the thermal responder 34, and the lower part of the PTC element 35. The surface electrode is in contact with an element connection protrusion 31-3 formed on the surface of the element connection electrode 31-2. The contact surface of the element connection protrusion 31-3 may be provided with a coating layer of Ag or an Ag alloy material, and particularly preferably an Ag—Cu clad material. When the temperature of the thermal actuator 34 of the first embodiment reaches 77 ° C. or higher, the snap inversion operation is performed in the shape shown in FIG. 3B, the circuit is cut off, and the circuit is turned off again at a temperature of 40 ° C. or lower. The circuit is restored to the initial connection state shown in Fig. 5 and enables the circuit ON / OFF operation by temperature detection. In the initial connection state of FIG. 3A, the thermal responder 34 is in direct contact with the movable arm 32 at the top of the curved surface. However, when the circuit is interrupted in FIG. The contact protrusion 32-2 and the connection protrusion 32-3 provided at the lower part of the movable arm 32 are brought into contact with each other at the outer edge portion. At that time, by making the height of the connection projection 32-2 on one side lower than the height of the other connection projection 32-3, the lifting height of the tip of the movable arm 32 is amplified and the movable contact 32-1 is fixed. The operation of separating from the contact 31-1 is assisted.

  Example 2 of the present invention includes a first terminal lead 41 made of a Cu-Sn alloy provided with a fixed contact 41-1 of Ag clad material and an element connection electrode 41-2, as in the temperature protection element 40 shown in FIG. A Cu—Be alloy movable arm 42 provided with a movable contact 42-1 made of an Ag clad material at the tip, and a Cu—Sn alloy first arm provided with an arm connection electrode 43-1 in contact with the movable arm 42. A two-terminal lead 43; a thermal responder 44 made of a Ni-Fe alloy / Cu-Mn-Ni alloy bimetal material that separates the fixed contact 41-1 and the movable contact 42-1, and the thermal responder 44; Polymer PTC element 45 (which includes a crystalline organic polymer and carbon black conductive filler is dispersed in the polymer) that is connected to the element connection electrode 41-2 and energized, and an opening for accommodating these Set up An insulating package 46 made of epoxy resin, and a metal thin plate 47 of a Ni-plated copper plate covering the opening of the insulating package 46, and the insulating package 46 is integrally formed with the both terminal leads 41 and 43 by insert molding, The movable arm 42, the thermal actuator 44, and the polymer PTC element 45 are accommodated in the package, the package opening is covered only with the metal thin plate 47, and the insulating package 46 is coated with the epoxy resin 48 applied along the outer edge of the metal thin plate 47. It is fixed and sealed.

  Although not particularly illustrated, the temperature protection element 40 according to the second embodiment may be modified so that the built-in thermal actuator 44 and the polymer PTC element 45 are not connected to the electric circuit. In other words, the thermally responsive body 44 in the modified example of the temperature protection element 40 is disposed separately from the movable arm 42 in the initial state, detects the overheating, and reversely operates to connect the fixed contact 41-1 and the movable contact 42-1. The polymer PTC element 45 that comes into contact with the movable arm 42 when it is separated and simultaneously abuts on the thermal responder 44 can be deformed so as to be connected to the thermal responder 44 and the element connection electrode 41-2 and to be energized.

  In the insulating package 46 of the second embodiment, the opening is covered with a thin metal plate 47, and the first terminal lead 41 that extends inside the insulating package 46 is exposed at the bottom of the insulating package 46. By forming the lead exposed surface 41-4, the thermal conductivity and heat dissipation of the insulating package 36 are improved, and the temperature sensitivity is further enhanced. The insulating package 46 is provided with a bank-shaped peripheral wall 49 along the periphery of the opening to assist the positioning of the thin metal plate 47 and to form a guide portion for the dispenser needle of the epoxy resin 48 to apply the liquid resin. In addition, a coating allowance having an L-shaped cross section is formed between the inner surface of the peripheral wall and the upper surface of the outer edge of the thin metal plate 47, and resin sagging is prevented by the interfacial tension between the coating allowance and the sealing resin.

  In the second embodiment, the use of the polymer PTC element 45 can further reduce the thickness of the insulating package 46. The surface electrode 45-1 applied to the polymer PTC element 45 is composed of a Cu base material Ni plating material. The surface electrode 45-1 above the polymer PTC element 45 is in contact with the thermal actuator 44, and the surface electrode 45-1 below the polymer PTC element 45 is in contact with the element connection electrode 41-2. The contact surface of the element connection electrode 41-2 may be provided with a coating layer of Ag or an Ag alloy material, particularly preferably an Ag-Cu clad material. When the temperature of the heat-responsive body 44 of Example 2 reaches 77 ° C. or higher, the snap inversion operation is performed in the shape shown in FIG. The circuit is restored to the initial connection state shown in Fig. 5 and enables the circuit ON / OFF operation by temperature detection. In the initial connection state of FIG. 4A, the thermal responder 44 is in direct contact with the movable arm 42 at the top of the curved surface. However, when the circuit is interrupted in FIG. The contact protrusion 42-2 and the connection protrusion 42-3 provided at the lower part of the movable arm 42 are brought into contact with each other at the outer edge. At that time, by making the height of the connection projection 42-2 on one side lower than the height of the other connection projection 42-3, the lifting height of the tip of the movable arm 42 is amplified and the movable contact 42-1 is fixed. The operation of separating from the contact 41-1 is assisted.

  The present invention is used for a temperature protection device such as a power supply device, and is particularly effective for a protection device for a large-capacity secondary battery such as a Li-ion battery.

10, 30, 40 ... temperature protection element,
11, 31, 41 ... first terminal lead,
11-1, 31-1, 41-1 ... fixed contact,
11-2, 31-2, 41-2 ... element connection electrode,
11-3, 31-3 ... element connection protrusions,
11-4, 21-4, 31-4 ... Terminal lead exposed surface,
12, 22, 32, 42 ... movable arm,
12-1, 22-1, 32-1, 42-1, 52-1 ... movable contacts,
12-2, 22-2, 32-2, 42-2, 52-2 ... connection protrusion (low),
12-3, 22-3, 32-3, 42-3, 52-3 ... connection protrusion (high),
12-4, 22-4, 52-4 ... arm bending point, 22-5 ... notch,
52-5 ... step, 52-6 ... depression, 52-7 ... notch,
13, 33, 43 ... second terminal lead,
13-1, 33-1, 43-1 ... arm connection electrodes,
14, 34, 44 ... heat-responsive body,
15, 35 ... PTC element, 45 ... Polymer PTC element 15-1, 35-1, 45-1 ... Surface electrode,
16, 36, 46 ... insulating package, 17, 37, 47 ... metal thin plate,
18, 38, 48 ... sealing resin, 39, 49 ... peripheral wall.

Claims (3)

A first terminal lead provided with a fixed contact ; a movable arm provided with a movable contact at one end thereof; and a second terminal lead electrically connected to the movable arm; A thermal responder that contacts and snaps in reverse at a predetermined temperature to separate the fixed contact and the movable contact; and a PTC element that is connected to the thermal responder and the first terminal lead and is energized. The movable arm, the thermally actuated body and the PTC element are housed in an insulating package integrally formed with the first terminal lead and the second terminal lead and provided with an opening. It said insulating openings in the temperature protection device seals affixed sealing covered with a lid member, the lid is made of only a metal sheet, a sealing resin provided around the only outer edges of the sheet metal Temperature protection device, characterized in that it seals the fixed seal package. The temperature protection element according to claim 1, wherein the insulating package is provided with a bank-like peripheral wall around the entire periphery of the opening. The movable arm is provided with a step and a depression at the end, and the lower surface of the distal end portion of the movable arm is processed into a letter-like convex shape, and a movable contact is formed on the surface of the convex portion on the lower surface of the distal end portion of the movable arm. The temperature protection element according to claim 1, wherein the temperature protection element is provided.

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