JP2019008920A - Current cutoff device and secondary battery pack including the same - Google Patents

Abstract

To provide a current cutoff device capable of restraining instantaneous interruption of power supply to each part of an electrical machine incident to the impact upon falling.SOLUTION: A current cutoff device 100 includes a breaker 1 including a fixed piece 2 having a fixed contact 21, a movable piece 3 having a movable contact 31, and pressing the movable contact 31 against the fixed contact 21 thus bringing into contact, a thermally-actuated element 4 for making the movable piece 3 transit from conduction state where the movable piece 3 is in contact with the fixed contact 21 to cut-off state where the movable contact 31 is separated from the fixed contact 21, by deforming as the temperature changes, and a first PTC thermistor 5 for conducting the fixed piece 2 and the movable piece 3 when the movable piece 3 is in cut-off state. The current cutoff device further includes a first tab lead 120 connected with the fixed piece 2, a second tab lead 130 connected with the movable piece 3, and a second PTC thermistor 150 for normally conducting the first and second tab leads 120, 130.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a small current interruption device used as a protection device for electrical equipment.

  Conventionally, a breaker is used as a protection device (safety circuit) for secondary batteries and motors of various electric devices. When the temperature of the secondary battery during charging / discharging rises excessively, or when an abnormality occurs such as when an overcurrent flows through a motor or the like equipped in a device such as an automobile or home appliance, Cut off current to protect secondary batteries and motors. Breakers used as such protective devices operate accurately following temperature changes (having good temperature characteristics) and have stable resistance when energized to ensure the safety of the equipment. It is required to be.

  Further, when the breaker is used as a protection device for a secondary battery or the like installed in a so-called mobile device such as a thin-type multifunctional mobile phone called a notebook personal computer, a tablet-type personal digital assistant device or a smartphone, In addition to ensuring safety, miniaturization is required. In particular, in recent portable information terminal devices, users have a strong desire for miniaturization (thinning), and devices newly released by each company are designed to be small in order to ensure superiority in design. The tendency to be remarkable is remarkable. Against this background, further miniaturization is strongly demanded for the current interrupting device mounted together with the secondary battery as one component constituting the portable information terminal device.

  The breaker is provided with a thermally responsive element that operates according to a temperature change and conducts or cuts off a current. Patent Document 1 discloses a breaker to which a bimetal is applied as a thermally responsive element. Bimetal is an element that is formed by laminating two types of plate-like metal materials having different coefficients of thermal expansion, and controls the conduction state of the contact by changing the shape in accordance with a temperature change. The breaker shown in the same document is a case in which parts such as a fixed piece, a movable piece, a thermally responsive element, and a PTC thermistor are housed in a case, and terminals of the fixed piece and the movable piece are connected to an electric circuit of an electric device. Used.

WO2011 / 105175 gazette

  While the above-described mobile devices such as notebook personal computers can be freely carried by the user, there is a risk of falling on the ground or the like. When an operating mobile device falls to the ground or the like, the movable piece elastically deforms due to the impact, the movable contact is separated from the fixed contact, and the power supply to each part of the device is momentarily cut off (hereinafter referred to as instantaneous interruption). ). Such instantaneous interruption of power supply may cause the operation of each part of the device to become unstable and cause problems such as loss of data being executed.

  The present invention has been made to solve the above-described problem, and an object of the present invention is to provide a current interrupting device that can suppress instantaneous power supply interruption to each part of an electric device due to an impact at the time of dropping.

  In order to achieve the above object, the present invention provides a fixed piece having a fixed contact, a movable piece having a movable contact, the movable piece pressing the movable contact against the fixed contact, and deforming as the temperature changes. When the movable piece is in the cut-off state, the thermally responsive element moves the movable piece from a conductive state in which the movable contact contacts the fixed contact to a cut-off state in which the movable contact is separated from the fixed contact. In a current interrupting device including a breaker including a first positive temperature coefficient thermistor for conducting the fixed piece and the movable piece, a first tab lead to which the fixed piece is connected and a first tab lead to which the movable piece is connected And a second positive temperature coefficient thermistor that always conducts the first tab lead and the second tab lead.

  In the current interrupting device according to the present invention, the current interrupting device further includes a case that houses the fixed piece, the movable piece, the thermally responsive element, and the first positive temperature coefficient thermistor, and the case and the second positive temperature coefficient thermistor It is desirable that the cases are arranged side by side in the short direction in plan view.

  In the current interrupt device according to the present invention, the first tab lead has a first connection part to which the fixed piece is connected and a second connection part to which one end of the second positive temperature coefficient thermistor is connected. In the short direction, the width of the second connection part is preferably narrower than the width of the first connection part.

  In the current interrupt device according to the present invention, the second tab lead has a third connection portion to which the movable piece is connected and a fourth connection portion to which the other end of the second positive temperature coefficient thermistor is connected. In the short direction, it is preferable that the width of the fourth connection portion is narrower than the width of the third connection portion.

  In the current interrupt device according to the present invention, at least one of the first tab lead or the second tab lead has an opening that penetrates in the thickness direction and opens outward from an edge in the short direction. Is desirable.

  In the current interrupting device according to the present invention, the resistance of the second positive characteristic thermistor is smaller than the resistance of the first positive characteristic thermistor below the trip temperature of the second positive characteristic thermistor. It is desirable that the resistance of the second positive temperature coefficient thermistor is greater than the resistance of the first positive temperature coefficient thermistor above the trip temperature of the positive temperature coefficient thermistor.

  A secondary battery pack according to the present invention includes the current interrupt device.

  The current interruption device of the present invention includes a breaker including a fixed piece, a movable piece, a thermally responsive element, and a first positive temperature coefficient thermistor. The current interrupt device further includes a first tab lead to which the fixed piece is connected, a second tab lead to which the movable piece is connected, and a second positive temperature coefficient thermistor that always conducts the first tab lead and the second tab lead. . As a result, the second positive characteristic that is in a low resistance state at a temperature lower than the trip temperature even when the breaker is subjected to an impact caused by the drop of the electric device to the ground or the like, and the movable contact is separated from the fixed contact by the impact. The conduction between the fixed piece and the movable piece is maintained through the thermistor. Therefore, the current interrupting device of the present invention can suppress instantaneous interruption of power supply to each part of the electric device by itself.

  The first positive characteristic thermistor provided mainly for securing a circuit breaker self-holding circuit when the movable piece is in the cut-off state and the second positive characteristic thermistor provided mainly as a measure against the instantaneous interruption are usually required. Different functions. In the present invention, the characteristics of each thermistor (trip temperature, resistance below the trip temperature, resistance above the trip temperature, etc.) are determined by the independent first positive characteristic thermistor and second positive characteristic thermistor. It can be set individually according to the function. Thereby, the instantaneous interruption of the electric power supply to each part of an electric equipment can be suppressed, maintaining the favorable temperature characteristic of a breaker.

The top view of the electric current interruption apparatus by one Embodiment of this invention. The perspective view which shows the state before an assembly which shows schematic structure of the breaker of FIG. Sectional drawing which shows the said breaker in an electricity supply state. Sectional drawing which shows the said breaker in an electric current interruption state. Sectional drawing which shows the said breaker at the time of fall. The semilogarithmic graph which compares and shows the resistance before and behind the trip of the 1st PTC thermistor and the 2nd PTC thermistor of the said breaker. (A) is a perspective view which shows the process of attaching a 2nd PTC thermistor to the said 1st tab lead and a 2nd tab lead, (b) is a perspective view which shows the process of attaching a breaker to the said 1st tab lead and a 2nd tab lead. The top view of the modification of the said electric current interruption apparatus. The top view of another modification of the said electric current interruption apparatus. The top view of another modification of the above-mentioned current interrupting device The circuit diagram of the safety circuit provided with the said electric current interruption apparatus. (A) is a perspective view of the safety circuit before the tab lead is bent, and (b) is a perspective view of the safety circuit after the tab lead is bent.

  A current interrupting device according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a schematic configuration of the current interrupt device 100. The current interrupt device 100 includes a breaker 1 that protects an electrical device from excessive temperature rise or overcurrent.

  2 to 4 show the configuration of the breaker 1. The breaker 1 includes a fixed piece 2 having a fixed contact 21, a movable piece 3 having a movable contact 31 at the tip, a thermally responsive element 4 that deforms with a temperature change, and a first PTC (Positive Temperature Coefficient) thermistor 5. A fixed piece 2, a movable piece 3, a thermally responsive element 4, a case 7 for housing a first PTC thermistor 5, and the like. The case 7 includes a case main body (first case) 71, a lid member (second case) 81 attached to the upper surface of the case main body 71, and the like.

  The fixed piece 2 is formed by, for example, pressing a metal plate mainly composed of copper or the like (other metal plate such as copper-titanium alloy, white or brass), and insert-molded into the case main body 71 by insert molding. Embedded. A terminal 22 electrically connected to an external circuit is formed at one end of the fixed piece 2, and a support portion 23 that supports the first PTC thermistor 5 is formed at the other end side. The first PTC thermistor 5 is placed on the convex protrusions (dubbed) 24 formed at three places on the support portion 23 of the fixed piece 2 and supported by the protrusions 24.

  The fixed contact 21 is formed at a position facing the movable contact 31 by clad, plating, coating, or the like of a conductive material such as copper, silver alloy, gold-silver alloy in addition to silver, nickel, nickel-silver alloy. The case body 71 is exposed from a part of the opening 73a. The terminal 22 protrudes outward from the edge of the case body 71. The support portion 23 is exposed from an opening 73 d formed inside the case main body 71.

  In the present application, unless otherwise specified, in the fixed piece 2, the surface on which the fixed contact 21 is formed (that is, the upper surface in FIG. 2) is the front surface and the opposite surface. Is described as the back side. When the direction from the fixed contact 21 toward the movable contact 31 is defined as the first direction and the direction opposite to the first direction is defined as the second direction, the front surface faces the first direction and the back surface faces the second direction. The same applies to other parts such as the movable piece 3, the thermally responsive element 4, and the first PTC thermistor 5.

  The movable piece 3 is formed in an arm shape symmetrical to the center line in the longitudinal direction by pressing a plate-shaped metal material mainly composed of copper or the like.

  A movable contact 31 is formed at the longitudinal end of the movable piece 3. The movable contact 31 is formed of the same material as that of the fixed contact 21, and is joined to the tip of the movable piece 3 by a technique such as clad or crimping in addition to welding.

  A terminal 32 that is electrically connected to an external circuit is formed at the other end of the movable piece 3 in the longitudinal direction. The movable piece 3 includes a contact portion 33 (corresponding to a base end of the arm-shaped movable piece 3 and a portion embedded in the case 7) and an elastic portion 34 between the movable contact 31 and the terminal 32. . The abutting portion 33 abuts the case main body 71 and the lid member 81 between the terminal 32 and the elastic portion 34, and has a protruding portion 33 a that projects in a wing shape in the short direction of the movable piece 3. By providing the protruding portion 33 a, the abutting portion 33 is sandwiched between the abutting portion 74 of the case main body 71 and the abutting portion 83 of the lid member 81 in a wide and large area. It is firmly fixed.

  The elastic part 34 extends from the contact part 33 toward the movable contact 31. The movable piece 3 is fixed by being sandwiched by the case body 71 and the lid member 81 at the abutting portion 33 from the front and back sides, and the elastic portion 34 is elastically deformed, whereby the movable contact 31 formed at the tip thereof is the fixed contact. The fixed piece 2 and the movable piece 3 can be energized by being pressed and brought into contact with the side 21.

  The movable piece 3 is curved or bent by pressing at the elastic portion 34. The degree of bending or bending is not particularly limited as long as the thermally responsive element 4 can be accommodated, and may be appropriately set in consideration of the elastic force at the reversal operation temperature and the normal rotation return temperature, the contact pressing force, and the like. In addition, a pair of protrusions (contact portions) 34 a and 34 b are formed on the lower surface of the elastic portion 34 so as to face the heat-responsive element 4. The protrusions 34a and 34b and the thermally responsive element 4 come into contact with each other, and the deformation of the thermally responsive element 4 is transmitted to the elastic portion 34 through the protrusions 34a and 34b (see FIGS. 2, 3 and 4).

  The thermally responsive element 4 has an initial shape curved in an arc shape and is formed by laminating thin plate materials having different thermal expansion coefficients. Of the thermally responsive elements 4, for example, a copper-nickel-manganese alloy or nickel-chromium-iron alloy is used for the thin plate material on the high expansion side, and for example, an iron-nickel alloy is used for the thin plate material on the low expansion side. Alloys such as white, brass, and stainless steel can be used in combination depending on the requirements. Each thin plate material is bonded by, for example, rolling.

  When the operating temperature is reached due to overheating, the curved shape of the thermally responsive element 4 is warped in reverse with a snap motion, and is restored when the temperature falls below the return temperature due to cooling. The initial shape of the thermoresponsive element 4 can be formed by pressing. As long as the elastic portion 34 of the movable piece 3 is pushed up by the reverse warp operation of the thermal responsive element 4 at the desired temperature and returns to the original state by the elastic force of the elastic portion 34, the material and shape of the thermal responsive element 4 are particularly limited. Although not intended, a rectangular shape is desirable from the viewpoint of productivity and the efficiency of the reverse warping operation, and a rectangular shape close to a square is desirable in order to efficiently push up the elastic portion 34 while being small.

  The first PTC thermistor 5 is disposed between the fixed piece 2 and the thermally responsive element 4. In other words, the support portion 23 of the fixed piece 2 is located directly below the thermally responsive element 4 with the first PTC thermistor 5 interposed therebetween. When the energization of the fixed piece 2 and the movable piece 3 is interrupted by the reverse warping operation of the thermoresponsive element 4, the current flowing through the first PTC thermistor 5 increases. If the first PTC thermistor 5 is a positive temperature coefficient thermistor that limits the current by increasing the resistance value as the temperature rises, the type can be selected as required, such as operating current, operating voltage, operating temperature, return temperature, The material and shape are not particularly limited as long as these properties are not impaired. In this embodiment, a ceramic sintered body containing barium titanate, strontium titanate or calcium titanate is used. In addition to the ceramic sintered body, a so-called polymer PTC in which conductive particles such as carbon are contained in a polymer may be used.

  The case main body 71 and the lid member 81 constituting the case 7 are formed of a thermoplastic resin such as flame retardant polyamide, polyphenylene sulfide (PPS), liquid crystal polymer (LCP), polybutylene terephthalate (PBT) having excellent heat resistance. Has been. A material other than the resin may be applied as long as characteristics equal to or higher than those of the above-described resin can be obtained.

  The case main body 71 is formed with a housing recess 73 for housing the movable piece 3, the thermally responsive element 4, the first PTC thermistor 5 and the like. The housing recess 73 includes openings 73 a and 73 b for housing the movable piece 3, an opening 73 c for housing the movable piece 3 and the thermally responsive element 4, and an opening 73 d for housing the first PTC thermistor 5. Have. Note that the edges of the movable piece 3 and the thermally responsive element 4 incorporated in the case main body 71 are brought into contact with each other by a frame formed inside the housing recess 73 and are guided when the thermally responsive element 4 is reversely warped. .

  In the lid member 81, a metal plate mainly composed of copper or the like or a metal plate such as stainless steel may be embedded by insert molding. The metal plate abuts on the surface of the movable piece 3 as appropriate, restricts the movement of the movable piece 3, and contributes to downsizing of the breaker 1 while enhancing the rigidity and strength of the cover member 81 and the case 7 as a casing. .

  As shown in FIG. 2, the lid member 81 is arranged so as to close the openings 73 a, 73 b, 73 c and the like of the case main body 71 that accommodates the fixed piece 2, the movable piece 3, the thermally responsive element 4, the first PTC thermistor 5, and the like. Attached to the case body 71. The case main body 71 and the lid member 81 are joined by, for example, ultrasonic welding.

  3 and 4 show an outline of the operation of the breaker 1. FIG. 3 shows the operation of the breaker 1 in a normal charge or discharge state. In a normal charge or discharge state, the thermally responsive element 4 maintains the initial shape before reverse warping. The terminals 22 and 32 of the breaker 1 are electrically connected through the fixed contact 21, the movable contact 31, the elastic part 34 of the movable piece 3, and the like. Further, the thermally responsive element 4 is separated from the movable piece 3 in the conductive state. Thereby, the contact pressure between the movable contact 31 and the fixed contact 21 is increased, and the contact resistance between them is reduced.

  FIG. 4 shows the operation of the breaker 1 in an overcharged state or an abnormality. When the temperature becomes high due to overcharge or abnormality, the thermally responsive element 4 that has reached the operating temperature is warped in reverse and comes into contact with the elastic portion 34 of the movable piece 3, and the elastic portion 34 is pushed up so that the fixed contact 21 and the movable contact 31 Are separated. At this time, the current flowing between the fixed contact 21 and the movable contact 31 is interrupted. On the other hand, the thermally responsive element 4 comes into contact with the movable piece 3 and a slight leakage current flows through the thermally responsive element 4 and the first PTC thermistor 5. In other words, the first PTC thermistor 5 causes the fixed piece 2 and the movable piece 3 to conduct through the thermally responsive element 4 that causes the movable piece 3 to shift to the cutoff state. Since the first PTC thermistor 5 continues to generate heat as long as such a leakage current flows, the resistance value is drastically increased while maintaining the thermally actuated element 4 in the reverse warping state, so that the current flows between the fixed contact 21 and the movable contact 31. There is only a small leakage current as described above (which constitutes a self-holding circuit). This leakage current can be used for other functions of the safety device.

  When the overcharge state is canceled or the abnormal state is resolved, the heat generation of the first PTC thermistor 5 is also stopped, and the thermal actuator 4 returns to the return temperature and restores the original initial shape. Then, the movable contact 31 and the fixed contact 21 come into contact again by the elastic force of the elastic portion 34 of the movable piece 3, the circuit is released from the interruption state, and returns to the conduction state shown in FIG.

  As shown in FIG. 1, in addition to the breaker 1, the current interrupt device 100 of the present embodiment includes a first tab lead 120 to which the fixed piece 2 is connected, a second tab lead 130 to which the movable piece 3 is connected, A second PTC thermistor 150 having both ends connected to the first tab lead 120 and the second tab lead 130 is further provided.

  In this application, for convenience, the tab lead to which the fixed piece 2 is connected is described as the first tab lead 120, and the tab lead to which the movable piece 3 is connected is described as the second tab lead 130. However, the fixed piece 2 and the tab lead 130 are connected. The movable piece 3 and the tab lead 120 may be connected.

  The first tab lead 120 and the second tab lead 130 are formed of a pressed plate-like metal. In the present embodiment, the first tab lead 120 and the second tab lead 130 that are L-shaped in plan view are mentioned, but may be linear or other shapes. One of the first tab lead 120 and the second tab lead 130 is connected to, for example, an electrode plate of a secondary battery, and the other is connected to, for example, a circuit board of an electric device. The second PTC thermistor 150 always makes the first tab lead 120 and the second tab lead 130 conductive outside the breaker 1 regardless of the contact state between the movable contact 31 and the fixed contact 21.

  For the second PTC thermistor 150, the above-described ceramic sintered body or polymer PTC may be appropriately employed. Electrodes 151 and 152 for improving the electrical connection between the first tab lead 120 and the second tab lead 130 are formed on the end face of the second PTC thermistor 150 from low resistance gold, silver, or a silver alloy. Yes.

  FIG. 5 shows the breaker 1 in a state in which the movable contact 31 is separated from the fixed contact 21 by an impact caused by dropping at a temperature lower than the operating temperature of the thermoresponsive element 4. When a large impact is applied to the breaker 1, the movable contact 31 is separated from the fixed contact 21, and the conduction between the fixed piece 2 and the elastic portion 34 is interrupted. In the figure, the state in which the first PTC thermistor 5 is separated from the fixed piece 2 is shown, but the state in which the thermal responsive element 4 is separated from the first PTC thermistor 5, the movable piece from the thermal responsive element 4 is shown. A state where 3 is separated may occur.

  In the current interrupting device 100, even if the conduction between the fixed piece 2 and the elastic portion 34 is interrupted due to any one of the above states, as shown in FIG. The conduction between the fixed piece 2 and the movable piece 3 is maintained via a certain second PTC thermistor 150. Therefore, the breaker 1 can suppress the instantaneous interruption of the power supply to each part of the electric equipment as a single unit.

  The second PTC thermistor 150 of this embodiment is arranged outside the case 7. Therefore, in the current interrupting device 100, a breaker having a configuration conventionally known as the breaker 1 (for example, a breaker disclosed in Patent Document 1) can be applied. Further, a breaker having a structure in which the movable piece is structurally separated into the arm terminal on the terminal side and the movable arm on the movable contact side as disclosed in Japanese Patent Laid-Open No. 2005-203277 may be applied. . In this case, the arm terminal and the movable arm may be fixed by welding or the like and structurally connected. As described above, in the current interrupting device 100, since the breaker having the same specification as the breaker already distributed in the market can be used, the development period can be shortened and the manufacturing cost can be easily suppressed. It becomes.

  The case 7 of the breaker 1 and the second PTC thermistor 150 are juxtaposed in the short direction (width direction) Dw in the plan view of the case 7. Thereby, the 1st tab lead 120 and the 2nd tab lead 130 are formed in flat form, The structure is simplified, The cost reduction of the electric current interruption apparatus 100 and especially the enlargement of the thickness direction can be suppressed.

  The second PTC thermistor 150 is desirably arranged so that the longitudinal direction of the breaker 1 and the longitudinal direction of the second PTC thermistor 150 are parallel to each other. Thereby, the enlargement of the thickness direction of the electric current interruption apparatus 100 can be suppressed.

  The first tab lead 120 includes a first connection part 121 to which the terminal 22 of the fixed piece 2 is connected, and a second connection part 122 to which the electrode 151 at one end of the second PTC thermistor 150 is connected. The second connection part 122 is formed so as to protrude from the first connection part 121 in the longitudinal direction perpendicular to the short direction Dw. For the connection between the terminal 22 and the first connection portion 121, a technique such as soldering or welding is applied. A technique such as soldering is applied to the connection between the electrode 151 of the second PTC thermistor 150 and the second connection portion 122. In the short direction Dw, the width of the second PTC thermistor 150 is smaller than the width of the breaker 1, and the width of the second connection part 122 is narrower than the width of the first connection part 121. Thereby, the enlargement of the transversal direction Dw of the electric current interruption apparatus 100 can be suppressed.

  On the other hand, the second tab lead 130 has a third connection part 131 to which the terminal 32 of the movable piece 3 is connected, and a fourth connection part 132 to which the electrode 152 at the other end of the second PTC thermistor 150 is connected. The fourth connecting portion 132 is formed to protrude from the third connecting portion 131 in the longitudinal direction perpendicular to the short direction Dw. For the connection between the terminal 32 and the third connection portion 131, a technique such as soldering or welding is applied. For the connection between the electrode 152 of the second PTC thermistor 150 and the fourth connection portion 132, a technique such as soldering is applied. In the short direction Dw, the width of the fourth connection portion 132 is narrower than the width of the third connection portion 131. Thereby, the enlargement of the transversal direction Dw of the electric current interruption apparatus 100 can be suppressed.

  When the first tab lead 120 is formed of a metal plate having a uniform thickness, the resistance value at the second connection portion 122 is larger than the resistance value at the first connection portion 121. Similarly, when the second tab lead 130 is configured by a metal plate having a uniform thickness, the resistance value at the fourth connection portion 132 is larger than the resistance value at the third connection portion 131. However, since the resistance values at the second connection portion 122 and the fourth connection portion 132 are sufficiently smaller than the resistance value of the second PTC thermistor 150 below the trip temperature, the second connection portion 122 and the fourth connection portion 132 are used. The influence of the voltage drop at the point on the operation of the electrical equipment at the time of dropping is negligible.

  The first tab lead 120 has an opening 123 penetrating in the thickness direction. By providing the opening 123 in the first tab lead 120, the first tab lead 120 has a region 124 in which the torsional rigidity and the bending rigidity are locally small in the vicinity of the opening 123. As a result, the region 124 is twisted when an external force is applied to the distal end portion 125 of the first tab lead 120 (that is, the end portion opposite to the first connection portion 121 and the second connection portion 122 across the region 124). Or the stress which arises in the 2nd connection part 122 is relieve | moderated by bending. As a result, the electrode 151 of the second PTC thermistor 150 is prevented from coming off from the second connection part 122.

  The opening 123 is preferably opened outward from the edge 126 in the short direction Dw of the first tab lead 120. As a result, the rigidity of the region 124 is further reduced, and the stress generated in the second connection portion 122 when an external force is applied to the distal end portion 125 is further relaxed. Further, the opening 123 is preferably formed on the distal end portion 125 side with respect to the first connection portion 121. Thereby, the stress which arises in the 1st connection part 121 when external force is applied to the front-end | tip part 125 is relieve | moderated.

  Similarly, the second tab lead 130 has an opening 133 that penetrates in the thickness direction. By providing the opening 133 in the second tab lead 130, the second tab lead 130 has a region 134 in which the torsional rigidity and the bending rigidity are locally small in the vicinity of the opening 133. As a result, the region 134 is twisted when an external force is applied to the distal end portion 135 of the second tab lead 130 (that is, the end opposite to the third connection portion 131 and the fourth connection portion 132 across the region 134). Or the stress which arises in the 4th connection part 132 is relieve | moderated by bending. As a result, the electrode 152 of the second PTC thermistor 150 is prevented from coming off from the fourth connection portion 132.

  The opening 133 is preferably opened outward from the edge 136 in the short direction Dw of the second tab lead 130. As a result, the torsional rigidity and bending rigidity of the region 134 are further reduced, and the stress generated in the fourth connecting portion 132 when an external force is applied to the distal end portion 135 is further relaxed. Further, it is desirable that the opening 133 is formed closer to the distal end portion 135 than the third connection portion 131. As a result, the stress generated in the third connection portion 131 when an external force is applied to the distal end portion 135 is relieved.

  The first PTC thermistor 5 and the second PTC thermistor 150 shift from the low resistance state to the high resistance state with heating. The temperature at which the PTC thermistor transitions from the low resistance state to the high resistance state is referred to as a trip temperature. The first PTC thermistor 5 and the second PTC thermistor 150 each have a unique trip temperature.

  The first PTC thermistor 5 provided mainly for securing the self-holding circuit of the breaker 1 when the movable piece 3 is in the shut-off state and the second PTC thermistor 150 provided mainly as a measure against the instantaneous interruption are usually required. Function is different. In the present invention, by the independent first PTC thermistor 5 and second PTC thermistor 150, the characteristics of each thermistor (trip temperature, resistance below the trip temperature, resistance above the trip temperature, etc.) are changed to the respective functions. Accordingly, it is possible to individually set. Thereby, the instantaneous interruption of the electric power supply to each part of an electric equipment can be suppressed, maintaining the favorable temperature characteristic of the breaker 1. FIG.

  More specifically, the second PTC thermistor 150 is tripped in order to effectively suppress instantaneous interruption of power supply to each part of the electric device when the electric device is dropped in a temperature region below the operating temperature of the thermoresponsive element 4. The temperature is desirably set higher than the operating temperature of the thermoresponsive element 4. Thereby, the current flowing through the second PTC thermistor 150 is sufficiently ensured, and the power supply to each part of the electrical equipment is maintained.

  FIG. 6 is a semi-logarithmic graph showing the resistance of the first PTC thermistor 5 and the second PTC thermistor 150 before and after trip (temperature range above and below the trip temperature) in comparison. In FIG. 6, the resistance on the vertical axis increases logarithmically, the resistance of the first PTC thermistor 5 is indicated by a curve R5, and the resistance of the second PTC thermistor 150 is indicated by a curve R6.

  Furthermore, in order to effectively suppress the instantaneous interruption of the power supply to each part of the electric device when the electric device is dropped in a temperature region lower than the operating temperature of the thermally responsive element 4, the temperature is less than the trip T6 temperature of the second PTC thermistor 150. The resistance R6 of the second PTC thermistor 150 is preferably smaller than the resistance R5 of the first PTC thermistor 5. As a result, when the electric device falls in a state where the first PTC thermistor 5 and the second PTC thermistor 150 are not tripped, a sufficient current is passed through the second PTC thermistor 150, and power supply to each part of the electric device is ensured. Maintained.

  On the other hand, it is desirable that the resistance R6 of the second PTC thermistor 150 is larger than the resistance R5 of the first PTC thermistor 5 at the trip temperature T6 or higher of the second PTC thermistor 150. Thereby, in a state where the first PTC thermistor 5 and the second PTC thermistor 150 are tripped, a sufficient leakage current flowing through the first PTC thermistor 5 is ensured, and the temperature of the thermal actuator 4 is maintained above the return temperature, It becomes easy to make the self-holding circuit including the responding element 4 and the first PTC thermistor 5 function effectively.

  The second PTC thermistor 150 is an overcurrent protection element having an allowable current. The allowable current of the second PTC thermistor 150 is the maximum current at which the second PTC thermistor 150 does not trip. The allowable current of the second PTC thermistor 150 is preferably smaller than the rated current of the breaker 1. As a result, when the thermally responsive element 4 reaches the operating temperature T4 and the conduction inside the breaker 1 is interrupted, a current exceeding the allowable current flows through the second PTC thermistor 150. Along with this, the second PTC thermistor 150 immediately trips, the supply of electric power to each part of the electric device is cut off, and the electric device is protected.

  Even when a large impact force is applied to the breaker 1 due to the fall of the electric device and the movable contact 31 is separated from the fixed contact 21, a current flows through the second PTC thermistor 150. However, when the time from when the movable contact 31 is separated from the fixed contact 21 by the impact force until it comes into contact with the fixed contact 21 again is defined as the instantaneous interruption time, the instantaneous interruption time is sufficiently short. Therefore, when the time from when the current starts to flow to the second PTC thermistor 150 until the trip temperature T6 is reached due to heat generation is defined as the trip time, the trip time is preferably set longer than the instantaneous interruption time. If the conduction inside the breaker 1 is resumed before the trip time elapses, the supply of electric power to the electric device is continued. The instantaneous interruption time can be obtained by experiments or the like.

  The trip temperature T5 of the first PTC thermistor 5 is higher than the operating temperature T4 of the thermoresponsive element 4, and the trip temperature T6 of the second PTC thermistor 150 is higher than the trip temperature T5 of the first PTC thermistor 5. With such a configuration, in the breaker 1, a self-holding function by the first PTC thermistor 5, prevention of an instantaneous interruption by the second PTC thermistor 150, and a favorable interruption operation by the thermally responsive element 4 can be realized. The ratio of the resistance change to the temperature change of the first PTC thermistor 5 and the second PTC thermistor 150 is represented by the slope of the curve R5 and the slope of R6.

  Before and after the trip, the ratio of the resistance change with respect to the temperature change of the second PTC thermistor 150 is preferably larger than the ratio of the resistance change with respect to the temperature change of the first PTC thermistor 5. As a result, when the electric device falls in a state where the first PTC thermistor 5 and the second PTC thermistor 150 are not tripped, it is easy to secure a sufficient current flowing through the second PTC thermistor 150, and stability to each part of the electric device is ensured. Power supply can be expected. Further, in the state where the first PTC thermistor 5 and the second PTC thermistor 150 are tripped, a current flowing through the first PTC thermistor 5 is sufficiently ensured, so that a self-holding circuit including the thermally responsive element 4 and the first PTC thermistor 5 is secured. It becomes easy to function effectively.

  FIG. 7 shows a manufacturing process of the current interrupt device 100. In the first step shown in FIG. 7A, the first tab lead 120 and the second tab lead 130 formed by pressing and the second PTC thermistor 150 are joined. More specifically, the electrode 151 of the second PTC thermistor 150 and the second connection part 122 of the first tab lead 120 and the electrode 152 of the second PTC thermistor 150 and the fourth connection part 132 of the second tab lead 130 are soldered, respectively. Etc. are connected by such a method.

  In the second step shown in FIG. 7B, the breaker 1 is mounted on the first tab lead 120 and the second tab lead 130. More specifically, the terminal 22 of the breaker 1 and the first connection part 121 of the first tab lead 120 and the terminal 32 of the breaker 1 and the third connection part 131 of the second tab lead 130 are respectively soldered, laser welded or resistance welded. Etc. are connected by such a method. In the present embodiment, since the opening 123 is formed in the first tab lead 120 and the opening 133 is formed in the second tab lead 130, respectively, external force is applied to the first tab lead 120 and the second tab lead 130 when the breaker 1 is mounted. Even when a rotational force is applied, the joining of the second PTC thermistor 150 to the first tab lead 120 and the second tab lead 130 is easily maintained.

  The present invention is not limited to the configuration of the above embodiment, and can be implemented with various modifications. That is, at least the current interrupt device 100 has a fixed piece 2 having a fixed contact 21, a movable contact 31, a movable piece 3 that presses the movable contact 31 against the fixed contact 21, and a temperature change. By deforming, the thermally responsive element 4 that moves the movable piece 3 from a conductive state in which the movable contact 31 contacts the fixed contact 21 to a cut-off state in which the movable contact 31 is separated from the fixed contact 21 and the movable piece 3 in a cut-off state. In some cases, the circuit breaker 1 includes a first PTC thermistor 5 that conducts the fixed piece 2 and the movable piece 3, and includes a first tab lead 120 to which the fixed piece 2 is connected and a second tab to which the movable piece 3 is connected. What is necessary is just to further provide the 2nd PTC thermistor 150 which makes the tab lead 130, the 1st tab lead 120, and the 2nd tab lead 130 always conduct.

(Modification)
FIG. 8 shows a current interrupt device 100 </ b> A that is a modification of the current interrupt device 100. The current interrupt device 100A differs from the current interrupt device 100 in that a pair of openings 123 are formed in the first tab lead 120A and a pair of openings 133 are formed in the second tab lead 130A. The configuration of the current interrupting device 100 described above can be adopted for portions of the current interrupting device 100A that are not described below.

  In the current interrupt device 100A, the edge 126 of the first tab lead 120A on the side where the second PTC thermistor 150 is disposed and the edge 127 opposite to the edge 126 (that is, the side where the breaker 1 is disposed) An opening 123 is formed. The pair of openings 123 are preferably formed so as to face the short direction Dw. Such an opening 123 further reduces the torsional rigidity and bending rigidity of the region 124, and further reduces the stress generated in the second connection part 122 when an external force is applied to the tip end part 125.

  Similarly, an opening 133 is formed in the edge 136 and the edge 137 of the second tab lead 130. The pair of openings 133 are preferably formed so as to face the short direction Dw. Such an opening 133 further reduces the torsional rigidity and bending rigidity of the region 134, and further reduces the stress generated in the fourth connection part 132 when an external force is applied to the distal end part 135.

  FIG. 9 shows a current interrupt device 100 </ b> B that is another modification of the current interrupt device 100. The current interrupt device 100B is different from the current interrupt device 100 in that the second PTC thermistor 150 is arranged close to the distal end portion 135 side of the second tab lead 130B. Accordingly, the second connection portion 122 of the first tab lead 120B extends to the tip portion 135 side, and the fourth connection portion 132 of the second tab lead 130B is retracted to the tip portion 135 side. The configuration of the current interrupting device 100 described above can be adopted for portions of the current interrupting device 100B that are not described below.

  FIG. 10 shows a current interrupt device 100 </ b> C that is another modification of the current interrupt device 100. The current interrupting device 100C is different from the current interrupting device 100B in that the second PTC thermistor 150 is arranged in parallel to the short direction Dw. That is, the second PTC thermistor 150 is arranged so that its longitudinal direction is orthogonal to the longitudinal direction of the breaker 1. Accordingly, the fourth connecting portion 132 of the second tab lead 130C is retracted to the center side of the second tab lead 130C in the short direction Dw. The configuration of the current interrupting device 100 described above can be adopted for portions of the current interrupting device 100C that are not described below.

  Further, the shapes of the breaker 1, the first tab lead 120, the second tab lead 130, the second PTC thermistor 150, etc. are not limited to those shown in FIG.

  FIG. 11 is a circuit diagram of a safety circuit including the current interrupt device 100. In FIG. 5, as shown in FIG. 5, a safety circuit 200 is shown in a state where the movable contact 31 is separated from the fixed contact 21 due to an impact caused by dropping or the like. The current interrupt device 100 is connected in series between the secondary battery 201 and the load 300 via the first tab lead 120, the second tab lead 130, and the like. Breaker 1 and second PTC thermistor 150 are connected in parallel in current interrupt device 100. Further, the first PTC thermistor 5 is connected in series with the thermally responsive element 4. Even when the movable contact 31 is separated from the fixed contact 21 due to an impact applied to the breaker 1 and the thermally responsive element 4 is separated from the movable piece 3, the first tab lead 120 is connected to the first tab lead 120 via the second PTC thermistor 150. Conductivity with the second tab lead 130 is maintained, and instantaneous interruption of power supply to the load 300 can be suppressed.

  FIG. 12 is a perspective view of the safety circuit 200. 12A, the safety circuit 200 includes a current interrupt device 100, a secondary battery pack 202 including a secondary battery 201, a circuit board 203 on which various electronic components are mounted, and a secondary circuit. A tab lead 204 for connecting the battery 201 and the circuit board 203 is provided. Instead of the current interrupt device 100, the current interrupt device 100A, 100B, or 100C may be applied.

  The leading end 125 of the first tab lead 120 is connected to the circuit board 203. The front end portion 135 of the second tab lead 130 is embedded in the cell of the secondary battery 201. The tab lead 204 protrudes from the cell of the secondary battery 201 to the outside of the main body of the secondary battery 201. The tip of the tab lead 204 is connected to the circuit board 203.

  A terrace 205 for supporting the breaker 1 and the safety circuit 200 is formed at the edge of the secondary battery 201 so as to protrude from the main body of the secondary battery 201.

  As shown in FIG. 12B, the circuit board 203 is stacked on the terrace 205 by folding the circuit board 203 at the tab leads 120 and 204.

  At this time, it is desirable that the thickness of the current interrupt device 100 is suppressed so that the total thickness of the terrace 205, the current interrupt device 100, and the circuit board 101 is equal to the main body of the secondary battery 201. According to the current interrupting device 100, since the thickness of the current interrupting device 100 due to the addition of the second PTC thermistor 150 is avoided, the thickness of the entire safety circuit 200 and the secondary battery pack 202 can be easily achieved. Can be suppressed.

  In addition, it is desirable that the width of the current interrupting device 100 is suppressed so that the protruding length of the terrace 205 on which the current interrupting device 100 is mounted is equal to the width of the circuit board 203. According to the current interrupting device 100, since the enlargement of the width of the current interrupting device 100 and the like due to the addition of the second PTC thermistor 150 is avoided, the entire safety circuit 200 and the secondary battery pack 202 can be easily downsized. Can be achieved.

DESCRIPTION OF SYMBOLS 1 Breaker 2 Fixed piece 3 Movable piece 4 Thermally responsive element 5 1st PTC thermistor (1st positive characteristic thermistor)
7 Case 21 Fixed contact 31 Movable contact 100 Current interrupt device 120 First tab lead 130 Second tab lead 150 Second PTC thermistor (second positive characteristic thermistor)
200 Safety circuit 202 Secondary battery pack

Claims (7)

A fixed piece having a fixed contact;
A movable piece that has a movable contact and presses the movable contact against the fixed contact;
A thermally responsive element that causes the movable piece to shift from a conductive state in which the movable contact contacts the fixed contact to an interrupted state in which the movable contact is separated from the fixed contact by being deformed with a temperature change;
In the current interrupting device including a breaker provided with a first positive temperature coefficient thermistor for electrically connecting the fixed piece and the movable piece when the movable piece is in the interrupted state,
A first tab lead to which the fixed piece is connected;
A second tab lead to which the movable piece is connected;
A current interrupting device, further comprising a second positive temperature coefficient thermistor that constantly conducts the first tab lead and the second tab lead. A case that accommodates the fixed piece, the movable piece, the thermally responsive element, and the first positive temperature coefficient thermistor;
2. The current interrupting device according to claim 1, wherein the case and the second positive characteristic thermistor are juxtaposed in a short direction in a plan view of the case. The first tab lead has a first connection portion to which the fixed piece is connected, and a second connection portion to which one end of the second positive temperature coefficient thermistor is connected,
3. The current interrupting device according to claim 2, wherein in the short-side direction, a width of the second connection portion is narrower than a width of the first connection portion. The second tab lead has a third connection part to which the movable piece is connected, and a fourth connection part to which the other end of the second positive temperature coefficient thermistor is connected,
4. The current interrupting device according to claim 2, wherein a width of the fourth connection portion is narrower than a width of the third connection portion in the short direction.   5. The device according to claim 2, wherein at least one of the first tab lead or the second tab lead has an opening that penetrates in a thickness direction and opens outward from an edge in the short direction. Current interrupt device. Below the trip temperature of the second positive temperature coefficient thermistor, the resistance of the second positive temperature coefficient thermistor is smaller than the resistance of the first positive temperature coefficient thermistor,
6. The current interrupting device according to claim 1, wherein a resistance of the second positive characteristic thermistor is higher than a resistance of the first positive characteristic thermistor at a temperature equal to or higher than a trip temperature of the second positive characteristic thermistor. .   A secondary battery pack comprising the current interrupt device according to claim 1.

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