JP2018206732A - breaker - Google Patents

Abstract

To provide a breaker enabling the current capacity thereof to be increased than conventional ones and also capable of being easily welded to a terminal of a cell.SOLUTION: The breaker comprises: a case 7; a fixing piece 2 equipped with a fixing contact point 23 arranged inside the case 7 and a first terminal 22 whose at least a part is exposed to the outside of the case 7; a movable piece 4 equipped with a movable contact point 43 arranged inside the case 7 and a second terminal 42 whose at least a part is exposed to the outside of the case 7; and a thermally-actuated element 5 which actuates the movable piece 4 so that the movable contact point 43 is brought into contact with and separated from the fixing contact point 23 by being deformed in accordance with temperature. The second terminal 43 is formed with a clad material equipped with at least a nickel layer and a copper layer.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a breaker incorporated in a secondary battery such as an electric device.

  For example, in a small electric device such as a smartphone, a breaker including a thermally responsive element is used to prevent an overcurrent from being supplied to a battery or a high temperature state (see Patent Document 1).

  As shown in FIG. 5, such a breaker 1 </ b> A includes a case 7 </ b> A in which a thermally responsive element is accommodated, and two copper alloy terminals 22 </ b> A and 42 </ b> A exposed from the case 7 </ b> A to the outside. One terminal 42A of the breaker 1A is attached to an aluminum positive terminal B1 protruding from a cell constituting the battery B, and the other terminal 22A is attached to a terminal of a control board C of the battery B. At the time of attachment, nickel tabs T are interposed between the terminal 42A of the breaker 1A and the positive electrode terminal B1 of the cell, and between the terminal 22A of the breaker 1A and the terminal of the control board C, for example, laser welding or resistance welding. Welded by.

JP 2013-171642 A

  Incidentally, in recent years, the number of battery cells has decreased, and the current capacity per cell tends to increase. For this reason, it is being demanded to reduce the resistance value of the entire battery pack 100A including the battery B, the breaker 1A, and the tab T in FIG.

  However, even if the resistance value of only the breaker 1A is reduced, if the positive electrode terminal B1 of the cell and one terminal 42A of the breaker 1A are welded through the nickel tab T as shown in FIG. A large amount of heat is generated by the large nickel tab T. The heat affects the thermoresponsive element in the case 7A through the terminal, and a desired operation may not be performed, and the function as the breaker 1A may be impaired.

  However, if the tab 42 made of nickel is omitted and the copper alloy terminal 42A of the breaker 1A is welded to the aluminum positive electrode terminal B1 of the cell, the resistance value of each metal is small and the thermal conductivity is good. Therefore, it is difficult to weld each terminal by, for example, laser welding or resistance welding.

  The present invention has been made in view of the above-described problems, and provides a breaker that can have a larger current capacity than conventional ones and can be easily welded to a cell terminal. Objective.

  That is, the breaker according to the present invention is disposed in the case, the fixed contact provided in the case, the fixed piece including the first terminal exposed at least partially outside the case, and the case. A movable piece including a movable contact, a movable piece having a second terminal exposed at least partially outside the case, and the movable contact contacting and separating from the fixed contact by being deformed according to temperature. A heat-responsive element for operating the movable piece, wherein the second terminal is formed of a clad material having at least a nickel layer and a copper layer.

  In such a case, since the second terminal has a nickel layer, the nickel layer of the second terminal is bonded to the aluminum electrode of the cell by a welding method such as resistance welding or laser welding. Can be easily welded. Therefore, the second terminal can be directly welded to the aluminum electrode without using a tab that bridges between the second terminal and the electrode of the cell. For this reason, the resistance value of the whole battery pack including the breaker according to the present invention can be reduced by the amount that can eliminate the tabs that have been conventionally required.

  Therefore, the current capacity of the entire battery pack can be increased. For example, when the current capacity per cell is increased by reducing the number of cells, the breaker according to the present invention is preferably used. it can.

  In order to make it easy to lower the resistance value of the second terminal while ensuring ease of welding of the second terminal to another terminal, the cladding material forming the second terminal is made of a nickel layer and a copper layer. Any Ni-Cu clad material having two layers may be used. In this case, for example, if the nickel layer of the second terminal is brought into contact with the aluminum electrode of the cell, sufficient heat can be generated particularly by resistance welding, and welding can be easily performed. In addition, since the portion other than the nickel layer is formed of the copper layer in the portion that does not contact the aluminum electrode of the second terminal, the resistance at the second terminal can be lowered.

  For example, in order to enable easy welding without aligning the direction of the second terminal to the aluminum electrode of the cell, the cladding material forming the second terminal is made up of a nickel layer, a copper layer, and a nickel layer. Any Ni-Cu-Ni clad material having three layers may be used.

  If the movable piece is provided with the movable contact at the tip and further includes an arm accommodated in the case, the movable piece is made of different materials on the movable contact side and the second terminal. Can do.

  In addition, in order to reduce the resistance value of the entire movable piece and further ensure the spring property of the arm required for the operation of the movable contact by the thermally responsive element, at least the second terminal. A part should just be exposed in the said casing and joined to the base end part of the said arm.

  In order to greatly reduce the resistance value of the arm and to obtain a spring property suitable for the function of the breaker, the arm may be formed of a copper plate.

  The first terminal can be easily welded to another electrode or terminal without using a tab, and the effect of lowering the resistance value and increasing the current capacity of the battery pack as a whole can be further obtained by omitting the tab. In order to achieve this, the first terminal may be formed of a clad material including a nickel layer and a copper layer.

  As a preferable embodiment of the breaker according to the present invention, from the viewpoint of durability of the movable contact and the fixed contact, the second terminal is welded to an aluminum positive terminal.

  As described above, in the breaker according to the present invention, at least the second terminal can be directly welded to the battery terminal without using the tab, and the entire battery pack including the breaker is reduced in resistance to reduce the current capacity. Can be bigger.

The schematic diagram which shows the breaker which concerns on one Embodiment of this invention, and the battery pack provided with the said breaker. The typical exploded perspective view of the breaker in the embodiment. FIG. 3 is a schematic cross-sectional view showing a thermal operation of the breaker in the same embodiment. The schematic diagram which shows the breaker which concerns on another embodiment of this invention, and the battery pack provided with the said breaker. The schematic diagram which shows the conventional breaker and the conventional breaker.

  A breaker 1 according to an embodiment of the present invention will be described with reference to the drawings.

  The breaker 1 shown in FIG. 1 is a case where an excessive temperature rise occurs or an excessive current flows in a battery pack 100 (secondary battery pack) used in a small electric device such as a mobile personal computer, a tablet terminal, or a smartphone. Further, it constitutes a part of a safety circuit that cuts off the current based on the temperature change. Further, the protection target of the breaker 1 is not limited to the above-described electric devices, and is also used as a protection circuit for a small motor, for example. In the present embodiment, the battery B is, for example, one cell or a plurality of cells connected in series, and a safety circuit is configured by providing one breaker of this embodiment for one battery B. .

  As shown in FIG. 1, the breaker 1 is connected to a first terminal 22 connected to a terminal of a control board C that controls energization to the battery B, and to an aluminum positive terminal B1 of the battery B. The second terminal 42 is provided. A nickel tab T is bridged between the first terminal 22 and the terminal of the control board C, and each terminal is welded by, for example, laser welding or resistance welding. On the other hand, the second terminal 42 is directly welded to the aluminum positive electrode terminal B1 of the battery B without using a tab. The negative terminal B2 of the battery B is directly connected to the terminal of the control board C.

  Below, the detail of the breaker 1 is demonstrated. As shown in FIGS. 1 and 2, the breaker 1 according to the present embodiment accommodates a switching mechanism S for interrupting a current under a predetermined condition in a case 7 having a substantially flat rectangular parallelepiped shape. Two terminals for connecting the switching mechanism S to other electrical elements and circuits are exposed to the outside from the opposing surfaces of the case 7.

  As shown in the exploded perspective view of FIG. 2 and the cross-sectional view of FIG. 3, the case 7 includes a base 71 formed in a substantially box shape and a plate-like cover 72 that covers the opening of the base 71. It is. Along with the temperature change formed by the fixed piece 2, the ceramic PTC (Positive Temperature Coefficient) thermistor 6, and the bimetal formed between the base 71 and the cover 72, the fixed contact 23 constituting the switching mechanism S is formed. The deformable thermoresponsive element 5 and the movable piece 4 having the movable contact 43 formed on the tip side are accommodated in order.

  The fixed piece 2 is a metal piece whose front end 21 is fixed to the base 71 in the case 7 and the first terminal 22, which is a base end, is exposed outside the case 7. In the present embodiment, the base 71 is formed and integrated by insert molding so as to cover the lower surface and the periphery of the distal end portion 21 of the fixed piece 2. A fixed contact 23 is formed at a portion of the distal end portion 21 of the fixed piece 2 exposed in the case 7.

  The movable piece 4 includes a second terminal 42 connected to the positive terminal B1 of the battery B on the base end side, and an arm 41 formed with a movable contact 43 contacting and separating from the fixed contact 23 on the distal end side. It is provided. In this embodiment, the arm 41 and the second terminal 42 are formed of different materials, and the base end side of the arm 41 is joined to the second terminal 42 in the case 7.

  The arm 41 is obtained by bending a plate-like metal into a generally arcuate shape. In the present embodiment, the copper plate is curved so that the movable contact 43 comes in contact with and separates from the fixed contact 23 in accordance with the operation of the thermally responsive element 5 described later. This copper plate preferably has a conductivity of 75% IACS or more from the viewpoint of a decrease in resistance value. Further, in addition to the improvement of the resistance value such as contact pressure and contact resistance due to the spring property or conductivity of the arm 41, the thickness of the arm 41 is different from that of the second terminal 42 from the viewpoint of operation and return temperature. In particular, the thickness of the arm 41 is preferably smaller than that of the second terminal 42 in order to avoid the enlargement of the thermally responsive element 5. The size of the thermal response element 5 is reduced, so that the breaker 1 can be downsized.

  The second terminal 42 is formed of a Ni—Cu clad material having a nickel layer and a copper layer, and one end thereof is integrated with the base 71 by insert molding. In this way, a flat surface is formed over the entire circumference of the upper surface of the base 71 so as to come into contact with the cover 72 and to be firmly joined. The surface of the second terminal 42 on the base 71 side is a nickel layer, and the cover 72 side of the second terminal 42 is a copper layer. Therefore, the base end side of the arm 41 made of a copper plate is joined to the copper layer of the second terminal 42 in the case 7. Further, as shown in FIG. 1, the nickel layer of the second terminal 42 is brought into contact with the aluminum positive electrode terminal B1 of the battery B and is welded by laser welding or resistance welding.

  In the present embodiment, the first terminal 22 of the fixed piece 2 is connected to the negative electrode B2 of the battery B via the control board C. Therefore, in the movable piece 4, electricity flows from the second terminal 42 to the arm 41 when the battery B is discharged. Note that when the connection to the battery B is reversed, the direction of the current flowing in the movable piece 4 is also opposite, but the function as the breaker 1 is exhibited in substantially the same manner.

  The thermally responsive element 5 is formed by subjecting a bimetal, which is a plate material in which two types of metals having different thermal expansion coefficients, are laminated to each other and performing a partial extrusion process while performing a bending process by a press. For example, a nickel-chromium-iron alloy (Ni-Cr-Fe) is used as the metal on the high expansion side of the plate material, and a nickel-iron alloy (Ni-Fe) is used as the metal on the low expansion side. The thing which improved rust property can be mentioned.

  FIG. 3A shows the breaker 1 at the time of normal energization, and the thermally responsive element 5 maintains an initial shape and has a curved shape so as to protrude toward the cover 72 side. In this state, the fixed contact 23 formed on the distal end portion 21 of the fixed piece 2 and the movable contact 43 formed on the arm 41 come into contact with each other, and an electric current is passed from the movable piece 4 through the fixed piece 2. Will flow.

  On the other hand, FIG. 3B shows the breaker 1 in an overcurrent state or an abnormality. When an overcurrent or high temperature state is reached, the thermoresponsive element 5 that has reached the operating temperature is warped in reverse and deformed into a curved shape so as to protrude toward the base 71. In this state, the thermoresponsive element 5 lifts the arm 41 upward, so that the fixed contact 23 and the movable contact 43 are separated from each other, and no current flows directly from the movable piece 4 to the fixed piece 2. Is cut off. That is, only a minute leakage current flows through the movable piece 4, the thermally responsive element 5, the PTC thermistor 6, and the fixed piece 2, and the current is substantially cut off. The leakage current causes heat generation of the PTC thermistor 6, subsequently heat transfer to the thermally responsive element 5 and continuation of the reversing operation, and a self-holding circuit is configured. In this way, if the PTC thermistor 6 is not configured to substantially cut off the current, after the current is cut off, the thermally responsive element 5 is cooled to return to the original forward warp shape when the temperature is lower than the return temperature. When the current is resumed, the operation of reversing the shape due to overheating is repeated indefinitely. That is, since the PTC thermistor 6 is provided in this embodiment, it is possible to prevent overheating and cooling from being repeated indefinitely.

  Thus, in the breaker of this embodiment, the second terminal 41 connected to the positive electrode terminal B1 made of aluminum of the battery B in the movable piece 4 is a clad material made of a nickel layer and a copper layer. Since it is formed, the second terminal 41 can be easily welded directly to the positive electrode terminal B1 without using a nickel tab as in the prior art.

  Therefore, it is possible to reduce one high-resistance tab as compared with the conventional case, and when viewed from the battery back 100 as a whole, the overall resistance value can be reduced and the current capacity can be increased.

  Further, since the second terminal 42 is not made of nickel but includes a copper layer, and the arm 41 is made of copper, the resistance value of the breaker 1 can be lowered.

  Further, since the arm 41 is made of copper, the arm 41 can be reduced in size by having elasticity suitable for moving the movable contact 43 against and away from the fixed contact 23.

  For these reasons, even if the number of cells of the battery B decreases and the current value increases, the breaker 1 of the present embodiment can be suitably used. For example, even in an application in which a current of 8 A or more flows through the breaker 1, a normal current interruption operation can be realized at a high temperature or when an abnormal current is flowing.

  In addition, the second terminal 42 is integrated with the base 71 by insert molding, and the edge of the upper surface of the base 71 is configured to contact the cover 72 over the entire circumference. Even if the second terminal 42 is twisted at the time, etc., the moment is applied to the base 71 and is not transmitted to the cover 72, so that the case 7 can be hardly broken.

  Another embodiment of the present invention will be described. In addition, the same code | symbol shall be attached | subjected about the member corresponding to the member demonstrated by the said embodiment.

  As shown in FIG. 4, the first terminal 22 of the fixed piece 2 is also formed of a clad material made of a nickel layer and a copper layer, and the first terminal 22 is directly welded to the terminal of the control board C without a tab. It doesn't matter. If it is such, since the tab for welding in the battery pack 100 can be eliminated, the resistance value can be further reduced to increase the current capacity. In addition, although the 1st terminal 22 is formed in the substantially L shape in this embodiment, you may form the 2nd terminal 42 in a general L shape similarly.

  Other embodiments will be described.

  The plate material forming the first terminal or the second terminal is not limited to a clad material formed of two layers of a nickel layer and a copper layer. For example, Ni having three layers of a nickel layer, a copper layer, and a nickel layer. It may be a -Cu-Ni clad material.

  As for the movable piece, the second terminal and the arm may be formed as a single body using a single material. That is, the entire movable piece may be formed of a clad material having a nickel layer and a copper layer.

  The second terminal may be welded to the negative terminal of the battery. Even when the terminal of the battery is formed of a metal other than aluminum, the second terminal may be directly welded without a tab. The welding method may be a welding method other than laser welding or resistance welding.

  The breaker of the present invention may be used not only for the battery safety circuit but also for other purposes.

  In addition, various modifications and combinations of the embodiments may be made without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 100 ... Battery pack 1 ... Breaker 2 ... Fixed piece 22 ... First terminal 23 ... Fixed contact 4 ... Movable piece 41 ... Arm 42 ... Second terminal 43 ..Movable contact 5 ... thermally responsive element 6 ... PTC thermistor 7 ... case

Claims (7)

Case and
A stationary contact disposed in the case, and a stationary piece including a first terminal at least partially exposed outside the case;
A movable contact comprising a movable contact disposed in the case, and a second terminal at least partially exposed outside the case;
A thermally responsive element that operates the movable piece to move the movable contact toward and away from the fixed contact by being deformed according to temperature,
The breaker, wherein the second terminal is formed of a clad material having at least a nickel layer and a copper layer.   The breaker according to claim 1, wherein the clad material forming the second terminal is a Ni-Cu clad material having two layers of a nickel layer and a copper layer.   The breaker according to claim 1, wherein the clad material forming the second terminal is a Ni-Cu-Ni clad material comprising three layers of a nickel layer, a copper layer, and a nickel layer. The movable piece further includes an arm provided with the movable contact at a tip portion and housed in the case;
The breaker according to any one of claims 1 to 3, wherein at least a part of the second terminal is exposed in the casing and joined to a base end portion of the arm.   The breaker according to claim 4, wherein the arm is formed of a copper plate.   The breaker according to any one of claims 1 to 5, wherein the first terminal is formed of a clad material including a nickel layer and a copper layer.   The breaker according to any one of claims 1 to 6, wherein the second terminal is welded to a positive electrode terminal made of aluminum.