JP6195910B2 - Protective device - Google Patents

Description

  The present invention relates to a protective device having a bimetal element and a PTC element that substantially cuts off a current flowing through an electric or electronic device (for example, a motor, a secondary battery pack) when an abnormality occurs. .

  Abnormalities such as when the electric device (for example, motor) flows excessively and the electric device reaches an abnormally high temperature, or when the electric device temperature becomes abnormally high for any reason other than excessive current When this occurs, it is necessary to cut off the current flowing through the electric device, eliminate such abnormality as necessary, and ensure the safety of the electric device. Bimetal elements are used as means for interrupting current.

  A bimetallic element has a sheet member made of bimetallic metal, and when the temperature of the bimetallic element itself exceeds a specific temperature or when the temperature of the surrounding atmosphere becomes high, the bimetallic element exceeds a specific temperature. When the temperature becomes high, it is configured to operate (i.e., to be deformed) and to interrupt a current flowing through the bimetal element.

  When such a bimetal element is incorporated into an electrical device, it will operate and cut off the current when the electrical device becomes abnormally hot due to excess current or for other reasons. Although the temperature of the electrical device decreases due to the interruption of the current, the bimetal element also returns to its original shape (that is, returns) because the temperature also decreases, and as a result, before ensuring the safety of the electrical device, It may allow the current to flow again.

  In order to prevent such a current from flowing again, it is necessary to ensure and maintain the state in which the bimetal element is activated. For this purpose, bimetal elements are arranged in series in the circuit of the electric device so that the current of the circuit can be cut off, and PTC elements are arranged in parallel to the bimetal elements. With such an arrangement, when the bimetal element is activated, the current flowing therethrough is diverted to the PTC element, and the PTC element generates Joule heat by the current, and the heat is transmitted to the bimetal element to transmit the bimetal element. The operating state of the element can be secured.

  As described above, a protection device is known in which movable contacts that are operated by the operation of a bimetal element in an electric circuit are arranged in series, and a PTC element is arranged in parallel to the bimetal element. Such a protection device is disclosed in, for example, Patent Document 1 below. In such a protection device, a resin base having a terminal has a PTC element, a bimetal element and an arm in a space provided in the resin base, and a cover provided with an upper plate in advance is disposed on the resin base. The resin base and the resin cover are bonded by an adhesive or ultrasonic melting.

JP 2005-203277 A

  In the conventional protection device as described above, when abnormal heat generation occurs at a position away from the protection device, or when an abnormality other than overcurrent, for example, overvoltage occurs, the electrical or electronic device can be properly protected. Can not. Therefore, the present invention provides a protective device capable of appropriately protecting a device to be protected even when abnormal heat generation occurs at a position away from the protective device or when an abnormality other than overcurrent occurs. Objective.

  As a result of intensive studies to solve the above problems, the present inventors have determined that, in addition to the main circuit including the movable contact that operates by the operation of the bimetal element, the secondary circuit including the PTC element that is energized in response to various abnormalities. It has been found that the above problems can be solved by providing a circuit, and the present invention has been achieved.

According to a first aspect of the present invention, there is provided a protective device comprising a resin base, a first terminal, a second terminal, a PTC element, an insulating layer, a bimetal element, an arm, an upper plate, and a resin cover,
In the resin housing defined by the resin base and the resin cover, the first terminal, the PTC element, the second terminal, the insulating layer, the bimetal element, the arm and the upper plate are stacked in this order,
A first terminal and an arm having a terminal function are arranged in series to constitute a main circuit,
The first terminal, the PTC element, and the second terminal are electrically connected in series to form a sub circuit,
In normal times, the main circuit is in a state where the first terminal and the arm are electrically connected in series via both contact points, while no current flows in the sub circuit,
In an abnormal state, when the subcircuit is energized, the PTC element generates heat due to this current, the bimetal element is activated by this heat, the electrical connection between the first terminal and the arm is cut off, and the main circuit is opened. A protection device is provided that is configured as described above.

  According to the present invention, there is a case where an abnormality other than an overcurrent has occurred by providing a sub-circuit that includes a PTC element and is energized in the event of an abnormality, in addition to the main circuit that is interrupted by the operation of the bimetal element. However, by energizing the subcircuit according to the abnormality, Joule heat is generated in the PTC element of the subcircuit, and this heat activates the bimetal element to open the main circuit. The electronic device can be appropriately protected.

FIG. 1 schematically shows a perspective view of a protection device 1A of the present invention of a three-terminal type. FIG. 2 schematically shows a cross-sectional view along a plane perpendicular to the plane including the straight line x ₁ -x ₂ of the protective device 1 A of FIG. FIG. 3 schematically shows an exploded perspective view obtained when the protection device 1A of FIG. 1 is temporarily disassembled into elements constituting the protection device 1A. FIG. 4 schematically shows a perspective view of the resin base of the protection device 1A of FIG. FIG. 5 schematically shows a perspective view of the first terminal of the protective device 1A of FIG. FIG. 6 schematically shows a perspective view of the protection device 1B of the present invention of a four-terminal type. FIG. 7 schematically shows a cross-sectional view along a plane perpendicular to the plane including the straight line x ₁ -x ₂ of the protection device 1 B of FIG. FIG. 8 schematically shows an exploded perspective view obtained when the protection device 1B of FIG. 6 is temporarily disassembled into elements constituting the protection device 1B. FIG. 9 schematically shows a perspective view of the resin base of the protection device 1B of FIG.

  A protective device 1A according to an embodiment of the present invention will be described in detail with reference to FIGS. FIG. 3 schematically shows a state in which the protection device 1A of the present invention shown in FIGS. 1 and 2 is disassembled for each element constituting the protection device 1A. FIG. FIG. 3 schematically shows an exploded perspective view obtained when the protective device 1A of the present invention is temporarily disassembled into elements constituting the protective device 1A, and the protective device of the present invention is obtained by assembling the elements shown in FIG. It should be noted that this is not the case.

  The protection device 1A of the present invention schematically has a structure as shown in FIGS. Specifically, the protective device 1 </ b> A includes a resin housing 8 defined by a resin base 4 having a first terminal 2 and a resin cover 6. The resin base 4 has a space 10, a part of the first terminal 2 is exposed at the bottom thereof, the PTC element 14 is disposed above the exposed portion 12, and the second terminal 16 is disposed above the exposed portion 12. An insulating layer 18 is disposed above it, a bimetal element 20 is disposed above it, and an arm 22 that also functions as a terminal is disposed above it. The first terminal portion 24, the second terminal portion 26 and the arm portion 28 penetrate the resin housing 8 and extend to the outside of the housing. The space 10 including the exposed portion 12 of the first terminal, the PTC element 14, a part of the second terminal 16, the insulating layer 18, the bimetal element 20 and a part of the arm 22 is sealed by the upper plate 30, The resin cover 6 covers the first terminal 2, the second terminal 16, and a part of the arm 22. In the protection device 1A, the first terminal 2 and the arm 22 constitute a main circuit, and the first terminal 2, the PTC element 14 and the second terminal 16 constitute a sub circuit. Hereinafter, such a protection device having three connection terminals with other electrical elements is also referred to as a “3-terminal type” protection device.

  In the three-terminal protection device 1A of the present invention, the first terminal 2 and the arm 22 are electrically connected in series via both contact portions 32 and 34 in a normal state. Moreover, the bimetal element 20 is in a state of being curved so as to protrude upward (arm side) as shown in the figure. The second terminal 16 and the bimetal element 20 are electrically cut off by the insulating layer 18. Under normal conditions, the current flows in the order of the main circuit, that is, the first terminal 2, the first terminal contact 32, the arm contact 34, and the arm 22 (or vice versa), and no current flows in the subcircuit. . When an abnormality occurs, energization of the subcircuit is started from the electrical element connected to the second terminal, and a current flows in the order of the subcircuit, that is, the first terminal 2, the PTC element 14, and the second terminal 16 (or vice versa). This current causes the PTC element 14 to trip (operate), generating Joule heat, and the bimetal element 20 is activated by the heat to deform from upward convex to downward convex, thereby pushing up the arm 22 upward, The electrical connection between the contact portion 34 and the contact portion 32 of the first terminal is cut off, and the main circuit is opened. Note that “normal” means that no abnormality has occurred in the electrical or electronic device to be protected, and “when abnormal” means, for example, a circuit to which the electrical or electronic device to be protected is connected. It means a situation in which an overcurrent flows, an overvoltage is applied, or abnormal heat is generated in or around the electrical or electronic device to be protected.

  In the three-terminal protection device 1A of the present invention, the first terminal 2 and the resin base 4 are integrally formed by insert molding. By performing insert molding in this way, the adhesion between the first terminal 2 and the resin base 4 can be enhanced. The resin base 4 has a space 10 and a part of the first terminal 2 is exposed at the bottom. A PTC element 14 is disposed on the exposed portion 12 of the first terminal 2. The first terminal 2 may have a plurality of, for example, three, for example, three dome-shaped contacts 36 on the exposed portion 12 so as to easily ensure electrical connection with the PTC element 14 (see FIG. 4). ).

  The first terminal 2 has a contact portion 32 with a contact portion 34 of the arm 22. The contact portion 32 can be formed by caulking a contact material in a hole provided through a corresponding position of the first terminal 2. In the present specification, “caulking” means that a hole provided through a certain member (for example, a plate for the first terminal) has a diameter equivalent to the diameter of the hole, and from the thickness of the hole. It means that another member (for example, contact material) having a large thickness (height) is fitted and another member is fixed to a certain member by crushing a portion protruding vertically from this hole. Note that the contact material does not necessarily have a cylindrical shape, and may have a prismatic shape or the like. By forming such a contact portion in the first terminal 2, it becomes possible to give the contact portion a large heat capacity, and even when a relatively large current is passed through the protective device, the temperature of the contact portion is rapidly increased. Can be prevented, and the holding current of the protective device can be increased.

Metal constituting the contact material is not particularly limited, preferably those having a large heat capacity, for example, silver - nickel, silver - _{copper, AgCdO, AgSnO 2, AgZnO,} AgSnOInO, AgCu, copper - tungsten alloy or the like are preferable. A 90% silver 10% nickel alloy is preferred from the viewpoints of low hardness, fine design of the contact portion shape, particularly thickness, and a large heat capacity.

  The first terminal 2 preferably has ribs 72 on at least a part of the first terminal, for example on the portion 38 as shown in FIG. In this specification, the “rib” refers to an element or structure for increasing the strength of a member in which the rib is installed. For example, a linear, rod-shaped, or strip-shaped reinforcing material installed on a member surface, or a member Examples include a structure in which a part of the surface is deformed into a convex shape or a concave shape. By forming such ribs, it is possible to increase the rigidity of the protective device, particularly the strength against the external pressure from the back surface (the side where the first terminal is exposed).

  The first terminal 2 is preferably bent in a crank shape so that the portion 38 including the exposed portion 12 is located at a deeper position in the space 10 of the resin base 4 as shown in FIG. The By setting it as such a shape, the capacity | capacitance of the space 10 of the resin base 4 can be enlarged. In this case, the portion 38 of the first terminal may be exposed on the back side of the resin base (the side opposite to the space 10 side). Thus, by exposing the portion 38 of the first terminal, the thickness of the protective device can be reduced, and heat generated inside the protective device such as the contact between the first terminal and the arm can be efficiently dissipated to the outside. And the holding current can be further improved.

  As described above, the first terminal portion 24 extends outward through the side surface of the resin housing 8. The part 24 of the first terminal is a part for electrically connecting the protection device 1A of the present invention to a predetermined electric element, and fulfills the original function as a terminal. As shown in the figure, a contact 40 may be provided on a part 24 of the first terminal.

  Preferably, the resin base 4 is formed from a resin having high fluidity. By using such a resin, since the resin is distributed in detail during insert molding, a finer design becomes possible. For example, the thickness of the bottom surface and the side surface of the resin base can be reduced and the size can be reduced.

  Examples of the resin having high fluidity include a resin having a flow length of 25 mm or more, preferably 30 mm. Such a resin is not particularly limited, and examples thereof include SZ6505HF (Sumitomo Chemical Co., Ltd.) and SZ6506HF (Sumitomo Chemical Co., Ltd.), and SZ6505HF is preferred.

  The above “flow length” is obtained by using PS10E1ASE (manufactured by Nissei Plastic Industry Co., Ltd.) as an injection molding machine through a 4.0 mmφ runner, a width of 1.5 mm, a thickness of 0.3 mm, and a length of 2.0 mm. Thus, the length of the product is defined as a product having a width of 5.0 mm and a thickness of 0.3 mm injection-molded at a pressure of 90 MPa for 6 seconds.

  The resin base 4 may be formed from a heat resistant resin. By using such a resin, deformation of the protection element can be prevented even when subjected to a high temperature environment such as a reflow furnace.

  Examples of the heat resistant resin include LCP resin, polyamide resin, PPS resin, and the like.

  In the three-terminal protection device 1A of the present invention, a PTC element 14 is disposed above the exposed portion 12 of the first terminal. As a result, the first terminal 2 and the PTC element 14 are electrically connected via, for example, the contact 36.

  As the PTC element, either a ceramic PTC element or a polymer PTC element may be used, but a polymer PTC element is preferably used. The polymer PTC element is advantageous in that the resistance value of the element itself is lower than that of the ceramic PTC element and self-destruction is unlikely to occur even when the temperature exceeds a certain level. In addition, the polymer PTC element has a lower voltage required to maintain the trip state than the ceramic PTC element, and can maintain the trip state even when the circuit voltage is low. As a result, it is advantageous in that the contact can be maintained in an open state (latched state) and chattering phenomenon that repeatedly opens and closes the contact can be prevented. Furthermore, when the holding current values are equal, the polymer PTC element is preferable in that it is smaller and has a lower resistance than the ceramic PTC element.

  The polymer PTC element is formed by extruding a conductive composition containing a polymer (for example, polyethylene, polyvinylidene fluoride, etc.) in which a conductive filler (for example, carbon black, nickel alloy, etc.) is dispersed. And the electrode (for example, metal foil) arranged on both sides thereof.

  The size and shape of the polymer PTC element are not particularly limited, but in the protective device of the present invention, for example, a disk-shaped element having a diameter of 2.0 mm or less and a thickness of 0.20 mm or less can be used.

  In the protection device of the present invention, when a polymer PTC element is used as the PTC element, the resistance value is preferably 0.8 to 10Ω, and more preferably 4.5 to 10Ω. By setting the resistance value of the polymer PTC element to 0.8Ω or more, the tripped state at 3V can be maintained. Further, by setting the resistance value of the polymer PTC element to 4.5Ω or more, it becomes possible to set the leakage current in a trip state at 3 V to 0.2 A or less. Further, by setting the resistance value of the polymer PTC element to 10Ω or less, it becomes easy to reduce the variation of the resistance value in the production.

  In this specification, the resistance value of the polymer PTC element is a polymer PTC obtained by pressure-bonding electrodes (preferably nickel foil) to both sides of a PTC element obtained by extruding a conductive composition containing a polymer. A current value measured with a voltage of 6.5 mV (direct current) applied at 25 ° C. between both electrodes of the element and a resistance value calculated from the applied voltage (measurement by a four-terminal method, measurement range of a resistance measuring instrument) The applied current of 100 mA). Since the resistance value of the electrode is negligibly small when compared with the resistance value of the PTC element, the resistance value of the PTC element is substantially equal to the resistance value of the PTC element.

  In the three-terminal protection device 1A of the present invention, a second terminal 16 is disposed above the PTC element 14. The PTC element 14 and the second terminal 16 are electrically connected by, for example, solder.

  The second terminal 16 is connected to an electrical element for energizing the sub circuit according to an abnormality, for example, a switching element, an FET (electrolytic effect transistor) or the like. When an abnormality occurs, a current is passed from the electric element to the PTC element via the second terminal, whereby the PTC element is brought into a high temperature / high resistance state, that is, tripped, and the bimetal element 20 is operated by the heat.

  As described above, the portion 26 of the second terminal extends outward through the side surface of the resin housing 8. The part 26 of the second terminal is a part for electrically connecting the protection device 1A of the present invention to a predetermined electric element. Although not shown in the drawing, a contact may be provided on a part 26 of the second terminal.

  In the three-terminal protection device 1 </ b> A of the present invention, an insulating layer 18 is disposed above the second terminal 16. The insulating layer 18 is supported on the step portion 42 provided in the space 10. By this insulating layer 18, the second terminal 16 and the bimetal element 20 are electrically separated.

  The insulating layer is made of an insulating material. Although it does not specifically limit as an insulating material, Preferably resin, ceramic, silicone, paper, rubber | gum etc. are mentioned.

  The thickness of the insulating layer is not particularly limited as long as electrical insulation between the second terminal and the bimetal element can be secured, but may be 50 to 500 μm, preferably 150 to 400 μm. The thinner the insulating layer, the more efficiently Joule heat generated in the PTC element can be transmitted to the bimetal element, and therefore it is preferably 250 μm or less, and more preferably 200 μm or less. Moreover, in order to ensure electrical insulation between the second terminal and the bimetal element, it is preferably 50 μm or more, and more preferably 100 μm or more.

  In the three-terminal protection device 1A of the present invention, a bimetal element 20 is disposed above the insulating layer 18. Further, the bimetal element 20 is under the thermal influence of the PTC element 14. The bimetal element 20 is not particularly limited as long as it can be deformed by Joule heat generated in the PTC element 14, and a known one can be used.

  The bimetal element 20 preferably has a surface area as large as possible, as long as the resin-based space 10 can allow it. By increasing the surface area, variations in operating temperature can be reduced, and the force that pushes the arm 22 upward when deformed during an abnormality increases.

  Preferably, the bimetal element 20 may have a protrusion, for example, a dome-shaped convex part 44 in the vicinity of the center part of the lower surface (PTC element side). The protrusion comes into contact with the PTC element 14 when the bimetal element 20 is actuated to protrude downward from the upward convex state. Since the arm 22 is further pushed upward by an amount corresponding to the height of the protrusion, the arm 22 can be sufficiently pushed up even when the degree of curvature of the bimetal element 20 itself is smaller. The electrical connection at the contact of one terminal can be more reliably interrupted.

  In the three-terminal protection device 1 </ b> A of the present invention, the arm 22 is positioned above the bimetal element 20 and is fixed to the resin base 4. The fixing method is not particularly limited, but it is preferable to bend the fixing portion 46 of the arm 22 into a crank shape and provide fitting portions 50 (for example, protruding portions) at both ends of the step portion 48. In this case, the to-be-fitted part 52 (for example, the recessed part in which the said protrusion part fits) corresponding to this fitting part is provided in the resin base 4. FIG. By fitting (press-fitting) these, the arm 22 can be fixed to the resin base 4. By setting it as such a form, the space 10 of the resin base 4 can be ensured more widely, and it becomes possible to install a larger bimetal element.

  Further, the arm 22 has a contact portion 34, and as shown in the figure, the contact portion 34 is curved so as to be located slightly below the horizontal direction (extending direction of the bottom surface of the resin base). It is preferable that it is formed. This contact portion 34 is normally in contact with the contact portion 32 of the first terminal, and when an abnormality occurs, the arm 22 is pushed upward by the deformation of the bimetal element 20 and this contact state is released.

  Similar to the contact portion 32 of the first terminal, the contact portion 34 can be formed by caulking a contact material in a hole provided at a corresponding position of the arm 22. By forming such a contact portion on the arm 22, it becomes possible to give the contact portion a large heat capacity, so that even when a relatively large current flows through the protective device, the temperature of the contact portion increases rapidly. Can be prevented, and the holding current of the protective device can be increased. Any one of the contact portion 32 of the first terminal and the contact portion 34 of the arm may be formed by caulking the contact material to the first terminal and / or the arm, but preferably both contact portions. Is formed by caulking the contact material.

  The metal which comprises the said contact material is the same as that which comprises the contact material which forms the contact part 32 of a 1st terminal.

  Moreover, the arm 22 may have convex parts 54 and 56 as shown in the figure. When the bimetal element 20 is actuated so that the convex portion protrudes downward from the upward convex state, the convex portion supports the one end of the bimetallic element by the convex portion 54, thereby increasing the height of the other end of the bimetallic element. Since the arm 22 can be pushed upward by an amount corresponding to the height of the convex portion 56, the arm 22 can be moved even when the degree of bending of the bimetal element 20 itself is smaller. It can be pushed up sufficiently, and the electrical connection at the contact point between the arm and the first terminal can be more reliably interrupted. Such convex portions are preferably provided at or near both ends in the length direction of the bimetal element 20 (left-right direction in FIG. 2) and separated in the length direction of the arm 22 (left-right direction in FIG. 2).

  Preferably, the arm 22 is bent into a crank shape in the space 10 as shown. By adopting such a shape, when the arm 22 is pushed up by the bimetal element 20 at the time of abnormality, the distance (contact gap) between the contact portion 32 and the contact portion 34 can be increased, and the contact state between the two can be further increased. It can be released reliably.

  As described above, the arm portion 28 extends outward through the side surface of the resin housing 8. The arm portion 28 is a portion for electrically connecting the protection element 1A of the present invention to a predetermined electric element, and performs the same function as the terminal. As shown, a contact 58 may be provided on a portion 28 of the arm.

  In the three-terminal protection device 1 </ b> A of the present invention, an upper plate 30 is disposed above the arm 22 in the space 10. The upper plate 30 is brought into contact with the arm 22 and / or the contact portion 34 that may be heated by heat from the bimetal element 20 when the bimetal element 20 is operated at a predetermined high temperature and pushes the arm 22 upward. And has the function of dissipating heat. Accordingly, the upper plate 30 preferably has excellent thermal conductivity, and heat is dissipated from the upper plate 30 through the arm in contact with it and through the arm portion 28. Therefore, the upper plate 30 is preferably formed of, for example, a metal sheet. As a result, the amount of heat transferred from the bimetal element 20 to the resin cover 6 can be reduced as much as possible, and the influence of the resin cover 6 due to heat can be minimized.

  As illustrated, the upper plate 30 substantially closes the space 10 defined by the resin base 4. Note that “substantially close” means that the molten resin used for molding cannot enter the space 10 when the resin cover 6 is formed by insert molding in the production of the protection device of the present invention. means. In other words, in the protection device of the present invention, it means that the resin used for molding does not enter the space 10 when the resin cover 6 is insert-molded.

  The upper plate 30 has a locking portion 60 that is fixed by being engaged with a locked portion 62 of the resin base 4. Preferably, the locking portion 60 has a saddle shape (hook shape), and the locked portion 62 has a cutout shape corresponding thereto. By adopting such a structure, the area required for engagement can be reduced, and as a result, the protective device can be further reduced in size, or a larger space 10 can be secured. A large bimetal element can be used.

  In the three-terminal protection device 1A of the present invention, the resin cover 6 is disposed so as to cover the upper plate 30. The resin cover 6 defines the resin housing 8 together with the resin base 4. The resin cover 6 and the resin base 4 can be bonded by, for example, an adhesive, ultrasonic welding, laser welding, or the like.

  Further, the resin cover 6 is a predetermined assembly made of the resin base 4 having the first terminal 2, the PTC element 14, the second terminal 16, the insulating layer 18, the bimetal element 20, the arm 22 and the upper plate 30 as shown in the figure. In the state where the first terminal part 24, the second terminal part 26 and the arm part 28 extend outward from the side surface of the mold, the resin is injection-molded, That is, it may be formed around the assembly by insert molding. The molten resin supplied to the mold by this insert molding is integrated with the resin at a location where the resin base 4 comes into contact with the resin portion, and an adhesive state between the resin base 4 and the resin cover 6 is ensured. In this case, in order to prevent the upper plate from being deformed by the pressure at the time of injection molding of the resin cover 6, before fixing the upper plate 30 to the resin base 4, preferably a part thereof, preferably above the central portion. It is preferable to insert-mold the resin cover part 7 in advance, fix the upper plate having the resin cover part 7 to the resin base, and then insert-mold the remaining part 7 'of the resin cover. Since the pressure of the resin supplied to the mold at the time of insert molding presses the upper plate 30 toward the resin base 4 (that is, downward in FIG. 2), the space 10 of the resin base 4 is closed by the upper plate 30. It can be secured even more. By forming the resin cover 6 in this manner, oxygen can be prevented from entering the space.

  In one aspect, a part of the upper surface portion of the upper plate 30 may be exposed from the resin cover 6. With such a configuration, the heat generated inside the protective device, particularly at the contact point, can be efficiently dissipated to the outside of the device, thereby increasing the holding current.

  In a further aspect, the upper plate 30 exposed at the top of the device as described above can also be used as an electrode. In this case, the arm portion 28 can be omitted. In this case, the current flowing through the device normally flows in the order of the first terminal 2, the contact portion 32 of the first terminal, the contact portion 34 of the arm, the arm 22, and the upper plate 30 (or vice versa). The electrical connection between the contact portion 32 of the first terminal and the contact portion 34 of the arm is interrupted.

  The resin constituting the resin cover 6 is not particularly limited, but is preferably the same as the resin constituting the resin base 4. By using the same resin, adhesion between the resin base 4 and the resin cover 6 can be further ensured.

In a preferred embodiment, the three-terminal protection device of the present invention comprises a resin base, a first terminal, a second terminal, a PTC element, an insulating layer, a bimetal element, an arm, an upper plate, and a resin cover.
(1) A first terminal, a PTC element, a second terminal, an insulating layer, a bimetal element, an arm and an upper plate are stacked in this order in a resin housing defined by a resin base and a resin cover.
(2) The first terminal and the arm having the terminal function are arranged in series to constitute the main circuit,
(3) The first terminal, the PTC element, and the second terminal are electrically connected in series to form a sub circuit,
(4) During normal operation, the main circuit is in a state where the first terminal and the arm are electrically connected in series via both contact portions. When an abnormality occurs, the subcircuit is energized, and this current The PTC element generates heat, the bimetal element is activated by this heat, the electrical connection between the first terminal and the arm is cut off, and the main circuit is opened,
(5) At least one of the contact portions of the first terminal and the arm is formed by caulking the contact material to the first terminal and / or the arm,
(6) The resin base is formed integrally with the first terminal by insert molding,
(7) At least a part of the first terminal has a rib,
(8) The resin base is formed from a resin having high fluidity,
(9) The upper plate has a hook-shaped locking portion, and is fixed to the resin base by engaging the locking portion with the notched locking portion of the resin base.
(10) The arm has a crank shape in the resin-based space,
(11) The fixed portion of the arm has a crank shape, and there are fitting portions at both ends of the step portion of the crank, and the arm is fitted by fitting the fitting portion to the fitted portion of the resin base. Fixed,
(12) The bimetal element has a protrusion near its center. However, at least one of the above features (5) to (12) may be provided, but preferably a plurality of, for example, 2 to 5, more preferably all.

  A protection device 1B according to another embodiment of the present invention will be described in detail with reference to FIGS. FIG. 8 schematically shows a state in which the protection device 1B of the present invention shown in FIGS. 6 and 7 is disassembled for each element constituting the protection device 1B. FIG. FIG. 9 schematically shows an exploded perspective view obtained when the protection device 1B of the present invention is temporarily disassembled into elements constituting the protection device 1B, and the protection device of the present invention is obtained by assembling the elements shown in FIG. It should be noted that this is not the case.

  The protection device 1B of the present invention schematically has a structure as shown in FIGS. The protection device 1B includes a third terminal 64 in addition to the components of the protection device 1A. The third terminal 64 is a first terminal 2 (specifically, the first terminal) in the protection device 1A in a subcircuit. The third terminal 64, the PTC element 14, the second terminal 16, the insulating layer 18, the bimetal element 20, and the arm in the resin housing 8 that is installed in place of the resin base 4 and the resin cover 6. 22 and the upper plate 30 are overlapped in this order, and the third terminal 64, the PTC element 14, and the second terminal 16 are electrically connected in series to form a sub circuit.

  Specifically, the protection device 1 </ b> B includes a resin housing 8 defined by a resin base 4 having a first terminal 2 and a third terminal 64 and a resin cover 6. In the resin base 4, the first terminal 2 and the third terminal 64 are electrically separated. The resin base 4 has a space 10, a part of the third terminal 64 is exposed at the bottom thereof, the PTC element 14 is disposed above the exposed portion 66, and the second terminal 16 is disposed above the exposed portion 66, An insulating layer 18 is disposed above, a bimetal element 20 is disposed above, and an arm 22 is disposed above the bimetal element 20. A part 24 of the first terminal, a part 26 of the second terminal, a part 68 of the third terminal and a part 28 of the arm penetrate the resin housing 8 and extend to the outside of the housing. The space 10 including a part of the first terminal 2, the exposed part 66 of the third terminal, the PTC element 14, a part of the second terminal 16, the insulating layer 18, the bimetal element 20 and a part of the arm 22 is sealed by the upper plate 30. Further, they are covered with a resin cover 6 except for a part 24 of the first terminal, a part 26 of the second terminal, a part 68 of the third terminal and a part 28 of the arm. In the protection device 1B, the first terminal 2 and the arm 22 constitute a main circuit, and the third terminal 64, the PTC element 14 and the second terminal 16 constitute a sub circuit. Hereinafter, such a protection device having four connection terminals with other electrical elements is also referred to as a “4-terminal type” protection device.

  In the four-terminal protection device 1B of the present invention, in normal times, the first terminal 2 and the arm 22 are electrically connected in series via both contact portions. Moreover, the bimetal element 20 is in a state of being curved so as to protrude upward (arm side) as shown in the figure. The second terminal 16 and the bimetal element 20 are electrically cut off by the insulating layer 18. Under normal conditions, the current flows in the order of the main circuit, that is, the first terminal 2, the first terminal contact 32, the arm contact 34, and the arm 22 (or vice versa), and no current flows in the subcircuit. . In the event of an abnormality, energization of the subcircuit is started from the electrical element connected to the second terminal (or the third terminal), and the subcircuit, that is, the third terminal 64, the PTC element 14, and the second terminal 16 in that order (or its) On the other hand, a current flows, and this current trips (operates) the PTC element 14 to generate Joule heat. The bimetal element 20 is activated by the heat and deforms from an upward convex to a downward convex. Pushed upward, the electrical connection between the contact part 34 of the arm and the contact part 32 of the first terminal is cut off, and the main circuit is opened.

  In the four-terminal protection device 1B of the present invention, the first terminal 2, the third terminal 64, and the resin base 4 are integrally formed by insert molding. By performing the insert molding in this way, the sealing performance between the first terminal 2 and the third terminal 64 and the resin base 4 can be enhanced. The resin base 4 has a space 10 and a part of the third terminal 64 is exposed at the bottom. The PTC element 14 is disposed on the exposed portion 66 of the third terminal 64. The third terminal 64 may have, for example, a plurality of, for example, three dome-shaped contacts 70 on the exposed portion 66 so as to easily secure electrical connection with the PTC element 14 (see FIG. 9). ).

  In the four-terminal protection device 1B of the present invention, the first terminal 2 does not have the first terminal portion 38 in the three-terminal protection device 1A and is electrically separated from the PTC element 14. Different from the three-terminal type protection device 1A.

  In the four-terminal protection device 1 </ b> B of the present invention, a part 68 of the third terminal extends outward from the side surface of the resin housing 8. The part 68 of the third terminal is a part for electrically connecting the protection device 1B of the present invention to a predetermined electric element. Although not shown in the drawing, a contact may be provided on a part 68 of the third terminal.

  In the four-terminal protection device 1B of the present invention, other components: the PTC element 14, the second terminal 16, the insulating layer 18, the bimetal element 20, the arm 22, the upper plate 30, and the resin cover 6 are three-terminal type. The configuration is substantially the same as the protection device 1A.

In a preferred embodiment, the four-terminal protection device of the present invention includes a resin base, a first terminal, a second terminal, a third terminal, a PTC element, an insulating layer, a bimetal element, an arm, an upper plate, and a resin cover. Consisting of
(1) A third terminal, a PTC element, a second terminal, an insulating layer, a bimetal element, an arm and an upper plate are stacked in this order in a resin housing defined by the resin base and the resin cover.
(2) The first terminal and the arm having the terminal function are arranged in series to constitute the main circuit,
(3) The third terminal, the PTC element, and the second terminal are electrically connected in series to form a sub circuit,
(4) During normal operation, the main circuit is in a state where the first terminal and the arm are electrically connected in series via both contact portions. When an abnormality occurs, the subcircuit is energized, and this current The PTC element generates heat, the bimetal element is activated by this heat, the electrical connection between the first terminal and the arm is cut off, and the main circuit is opened,
(5) At least one of the contact portions of the first terminal and the arm is formed by caulking the contact material to the first terminal and / or the arm,
(6) The resin base is formed integrally with the first terminal and the third terminal by insert molding,
(7) At least a part of the first terminal and / or the third terminal has a rib,
(8) The resin base is formed from a resin having high fluidity,
(9) The upper plate has a hook-shaped locking portion, and is fixed to the resin base by engaging the locking portion with the notched locking portion of the resin base.
(10) The arm has a crank shape in the resin-based space,
(11) The fixed portion of the arm has a crank shape, and there are fitting portions at both ends of the step portion of the crank, and the arm is fitted by fitting the fitting portion to the fitted portion of the resin base. Fixed,
(12) The bimetal element has a protrusion near its center. However, at least one of the above features (5) to (12) may be provided, but preferably a plurality of, for example, 2 to 5, more preferably all.

  The protective device of the present invention can be miniaturized, and can be, for example, a size having a length of 5.0 mm or less, a width of 3.0 mm or less, and a height of 0.9 mm or less. The size can be 6 mm, width 2.8 mm, and height 0.88 mm.

  The protection device of the present invention can be suitably used as a protection device for lithium ion battery cells such as mobile phones and tablet devices.

DESCRIPTION OF SYMBOLS 1A ... Protection apparatus; 1B ... Protection apparatus; 2 ... 1st terminal; 4 ... Resin base;
6 ... Resin cover; 7, 7 '... Part of resin cover; 8 ... Resin housing;
DESCRIPTION OF SYMBOLS 10 ... Space; 12 ... Exposed part; 14 ... PTC element; 16 ... 2nd terminal;
18 ... Insulating layer; 20 ... Bimetal element; 22 ... Arm;
24 ... part of the first terminal; 26 ... part of the second terminal;
28 ... a part of the arm; 30 ... an upper plate; 32 ... a contact part of the first terminal;
34 ... arm contact; 36 ... contact; 38 ... part of the first terminal;
40 ... Contact; 42 ... Step part; 44 ... Convex part; 46 ... Fixed part; 48 ... Step part;
50 ... fitting part; 52 ... mated part; 54, 56 ... convex part; 58 ... contact point;
60 ... locking part; 62 ... locked part; 64 ... third terminal; 66 ... exposed part;
68 ... Part of the third terminal; 70 ... Contact; 72 ... Rib

Claims (16)

A protective device comprising a resin base, a first terminal, a second terminal, a PTC element, an insulating layer, a bimetal element, an arm, an upper plate and a resin cover,
In the resin housing defined by the resin base and the resin cover, the first terminal, the PTC element, the second terminal, the insulating layer, the bimetal element, the arm and the upper plate are stacked in this order,
A first terminal and an arm having a terminal function are arranged in series to constitute a main circuit,
The first terminal, the PTC element, and the second terminal are electrically connected in series to form a sub circuit,
In normal times, the main circuit is in a state where the first terminal and the arm are electrically connected in series via both contact points, while no current flows in the sub circuit,
In an abnormal state, when the subcircuit is energized, the PTC element generates heat due to this current, the bimetal element is activated by this heat, the electrical connection between the first terminal and the arm is cut off, and the main circuit is opened. It is comprised so that the protective device characterized by the above-mentioned. And having a third terminal,
In place of the first terminal, the third terminal constitutes a subcircuit,
In the resin housing defined by the resin base and the resin cover, the third terminal, the PTC element, the second terminal, the insulating layer, the bimetal element, the arm and the upper plate are stacked in this order. Item 2. The protective device according to Item 1.   The protective device according to claim 1 or 2, wherein either one of the contact portions of the first terminal and the arm is formed by caulking a contact material to the first terminal and / or the arm.   The protection device according to any one of claims 1 to 3, wherein the contact portions of both the terminal and the arm are formed by caulking a contact material to the terminal and the arm.   The protective device according to claim 1, wherein the contact material is a silver-nickel alloy.   The protective device according to claim 1, wherein the resin base is formed integrally with the first terminal and, if present, the third terminal by insert molding.   The protection device according to any of claims 1 to 6, wherein at least part of the first terminal or, if present, the third terminal has a rib.   The protection device according to any one of claims 1 to 7, wherein the resin base is formed of a resin having high fluidity.   The upper plate has a hook-shaped locking portion, and the upper plate is fixed to the resin base by engaging the locking portion with a notched locking portion of the resin base. The protective device according to any one of 8.   The protection device according to claim 1, wherein the arm has a crank shape in a resin-based space.   The fixed part of the arm has a crank shape, and there are fitting parts at both ends of the step part, and the arm is fixed by fitting the fitting part to the fitted part of the resin base. The protective device according to claim 1.   The protective device according to claim 1, wherein the bimetal element has a protrusion in the vicinity of the center thereof. It has a resin base, a first terminal, a second terminal, a PTC element, an insulating layer, a bimetal element, an arm, an upper plate, and a resin cover.
(1) A first terminal, a PTC element, a second terminal, an insulating layer, a bimetal element, an arm and an upper plate are stacked in this order in a resin housing defined by a resin base and a resin cover.
(2) The first terminal and the arm having the terminal function are arranged in series to constitute the main circuit,
(3) The first terminal, the PTC element, and the second terminal are electrically connected in series to form a sub circuit,
(4) During normal operation, the main circuit is in a state where the first terminal and the arm are electrically connected in series via both contact portions. When an abnormality occurs, the subcircuit is energized, and this current The PTC element generates heat, the bimetal element is activated by this heat, the electrical connection between the first terminal and the arm is cut off, and the main circuit is opened,
(5) At least one of the contact portions of the first terminal and the arm is formed by caulking the contact material to the first terminal and / or the arm,
(6) The resin base is formed integrally with the first terminal by insert molding,
(7) At least a part of the first terminal has a rib,
(8) The resin base is formed from a resin having high fluidity,
(9) The upper plate has a hook-shaped locking portion, and is fixed to the resin base by engaging the locking portion with the notched locking portion of the resin base.
(10) The arm has a crank shape in the resin-based space,
(11) The fixed portion of the arm has a crank shape, and there are fitting portions at both ends of the step portion of the crank, and the arm is fitted by fitting the fitting portion to the fitted portion of the resin base. Fixed,
(12) The protective device, wherein the bimetal element has a protrusion near the center. Comprising a resin base, a first terminal, a second terminal, a third terminal, a PTC element, an insulating layer, a bimetal element, an arm, an upper plate and a resin cover;
(1) A third terminal, a PTC element, a second terminal, an insulating layer, a bimetal element, an arm and an upper plate are stacked in this order in a resin housing defined by the resin base and the resin cover.
(2) The first terminal and the arm having the terminal function are arranged in series to constitute the main circuit,
(3) The third terminal, the PTC element, and the second terminal are electrically connected in series to form a sub circuit,
(4) During normal operation, the main circuit is in a state where the first terminal and the arm are electrically connected in series via both contact portions. When an abnormality occurs, the subcircuit is energized, and this current The PTC element generates heat, the bimetal element is activated by this heat, the electrical connection between the first terminal and the arm is cut off, and the main circuit is opened,
(5) At least one of the contact portions of the first terminal and the arm is formed by caulking the contact material to the first terminal and / or the arm,
(6) The resin base is formed integrally with the first terminal and the third terminal by insert molding,
(7) At least a part of the first terminal and / or the third terminal has a rib,
(8) The resin base is formed from a resin having high fluidity,
(9) The upper plate has a hook-shaped locking portion, and is fixed to the resin base by engaging the locking portion with the notched locking portion of the resin base.
(10) The arm has a crank shape in the resin-based space,
(11) The fixing portion of the arm has a crank shape, and there are fitting portions at both end portions of the step portion of the crank. Fixed,
(12) The protective device, wherein the bimetal element has a protrusion near the center.   The protective device according to claim 1, wherein the top plate is exposed from an upper portion of the resin cover.   The protective device according to any one of claims 1 to 15, which has a size of 5.0 mm or less in length, 3.0 mm or less in width, and 0.9 mm or less in height.

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