Battery pack

Abstract

To provide a battery pack 1 with a battery stack 3 including plural cells and conductor members 5+, 5-, 6 electrically connected to electrode terminals 4+, 4- of the stack by mechanical connection stored in an enclosure 2, which is configured so that the connection between the stack and the conductor member is capable of being separated when abnormal heat or temperature rises inside the enclosure with a compact configuration as possible.SOLUTION: A battery pack 1 includes a separating member 13 made of a shape memory alloy that deforms in an environment exceeding a predetermined temperature. The separating member is arranged so that, in a state that allows mechanical connection between the electrode terminals of the stack and the conductor member in an environment below the predetermined temperature, and deforms in an environment where the temperature exceeds the predetermined temperature, and the electrode terminals are arranged to break the mechanical connection between the electrode terminals and the conductor member of the stack, thereby interrupting electrical continuity between the electrode terminals and the conductor members.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a battery pack that houses a battery stack including a plurality of battery cells, and more specifically to a fail-safe structure for bus bars, conductors, cables, wire harnesses, and the like (hereinafter collectively referred to as "conductor members") that connect between the output terminals of the battery pack and the battery stack and between the battery stacks themselves. [Background technology]

[0002] Battery packs installed in various machinery and equipment, such as electric vehicles, for driving or operating them are equipped with various fail-safe mechanisms to cut off electrical continuity between the outside of the battery pack and the battery cells when the battery pack generates heat. For example, Patent Document 1 proposes a configuration in which a heat-sensitive deformable member is attached to the shank of a bolt constituting the positive electrode terminal of a secondary battery, and the member expands in the axial direction of the shank when the shank reaches its shape recovery temperature. When the heat is generated, the heat-sensitive deformable member expands, tearing off the shank and breaking the electrode terminal, thereby cutting off electrical continuity between the battery cells and the outside. Patent Document 2 discloses a configuration in which multiple cylindrical battery cells are arranged in a pack case, in which one end of a conductive member connecting the electrode terminals of the cells is fixed to the electrode terminal of one cell, and the other end contacts the electrode terminal of the other cell at normal temperatures. When the temperature rises, the conductive member lifts off the electrode terminal, cutting off electrical continuity between the cell and the outside. Furthermore, although not a battery pack configuration, Patent Document 3 proposes a configuration in which a fuse section is integrally provided at each output section of a bus bar that branches from an input section connected to a power source to multiple output sections in an in-vehicle electrical connection box or the like, and when a large current flows, the fuse section melts and cuts off electrical continuity to the output section. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2013-211144 [Patent Document 2] Patent Publication No. 2023-535657 [Patent Document 3] Patent Publication No. 2002-51432 Summary of the Invention [Problem to be solved by the invention]

[0004] As shown schematically in FIG. 1, in a configuration in which a plurality of battery stacks 3 (hereinafter referred to as "stacks") are housed within a housing 2 of a battery pack 1, as shown in FIG. 5, the electrode terminals (4+, 4-) of the stacks 3 are electrically connected by being mechanically coupled to a conductor member 6, and the positive electrode terminals 4+ and negative electrode terminals 4- at the ends of a group of a plurality of stacks 3 are electrically connected by being mechanically coupled to a total + (plus) bus bar 5+ and a total - (minus) bus bar 5-, which are conductor members, respectively, and the total + bus bar 5+ and the total - bus bar 5- are connected to output terminals (positive electrode, negative electrode) 9 that transmit power to an electric device DM such as a motor via junction boxes 7+, 7- and conductors 8+, 8-, respectively. The junction boxes 7+, 7- are provided with relays that selectively establish and break conduction between the total + busbar 5+ and total - busbar 5- and the positive and negative poles of the output terminals 9, and controlling the operation of the relays controls the output of power from the output terminals 9. Furthermore, when an abnormality occurs in a cell or stack, the relays in the junction boxes 7+, 7- are configured to break conduction between the total + busbar 5+ and the conductor (conductor member) 8+, and between the total - busbar 5- and the conductor (conductor member) 8-, respectively, so that the voltage of the stack is not transmitted to the output terminals 9.

[0005] In this regard, the relays of the junction boxes 7+, 7- are configured to be able to cut off electrical continuity between the + busbar 5+ and the - busbar 5- and the output terminal 9 in the event of an abnormal short circuit in the pack due to some cause such as an impact or deformation of the casing 2 (such as damage to the casing when the battery pack is mounted on a vehicle and the battery pack comes into contact with an obstacle), resulting in abnormal heat generation, or a thermal diffusion phenomenon in the stack 3 (a chain reaction of heat and high-temperature debris being released outside the cells due to a short circuit inside the cells, etc.). However, normally, electrical continuity is maintained between the busbars and the stack electrodes at the connection portion 10a between the + busbar 5+ and the positive terminal 4+ of the stack 3 and the connection portion 10b between the - busbar 5- and the negative terminal 4- of the stack 3 (see FIG. 5). Therefore, even if electrical continuity is cut off by the relays of the junction boxes 7+, 7-, the stack voltage remains applied to the busbars 5+, 5- as a whole. Bus bars are usually covered with an insulating coating or spaced apart from their surroundings to prevent short circuits, but if the temperature inside the housing 2 becomes abnormally high and the insulating coating on the bus bars comes off, or if components inside the housing 2 deform or displace, causing the bus bars to short circuit with their surroundings, the battery voltage may be applied to areas where it should not be applied. In particular, the total bus bar 5 connecting the negative electrodes at the ends of the multiple stacks 3 to the junction box 7 generally extends a relatively long distance, which increases the chance of short circuits occurring with their surroundings. To avoid such a situation, when abnormal heat is generated or the temperature is abnormally high inside the housing 2, it is preferable to cut off the conduction between the electrode terminals (4+, 4-) of the stack 3 and the conductor members (5+, 5-, 6) such as bus bars not only in the relays of the junction boxes 7+, 7- but also at the connection 10b between the total-bus bar 5- and the negative terminal 4- of the stack 3, or further at the connection 10a between the total+bus bar 5+ and the positive terminal 4+ of the stack 3, and at the connection 11 between the conductor member 6 that connects the stacks and the stack electrode terminal. In this case, because there is not much space between the stack and the conductor member such as the bus bar, it is preferable to configure the conduction cutoff mechanism as compactly as possible.

[0006] Thus, the main object of the present invention is to provide a battery pack as described above that is as compact as possible in configuration and that allows the stack to be disconnected from conductive members such as bus bars when abnormal heat is generated inside the housing or when the temperature is abnormally high. [Means for solving the problem]

[0007] According to the present invention, the above object is achieved by a battery pack that houses a battery stack including a plurality of cells within a housing, and a conductor member that is mechanically connected to the electrode terminals of the battery stack and thereby electrically conductive, wherein a separating member made of a shape memory alloy that deforms in an environment above a predetermined temperature is in a state between the electrode terminals of the stack and the conductor member in an environment below the predetermined temperature, allowing the mechanical connection between the electrode terminals of the stack and the conductor member, and is arranged to deform in an environment above the predetermined temperature, thereby breaking the mechanical connection between the electrode terminals of the stack and the conductor member and interrupting electrical conduction between the electrode terminals and the conductor member.

[0008] In the above configuration, as already mentioned, a "battery pack" refers to a battery housed inside a housing that is installed in an electric vehicle or other machinery or equipment for driving or operating the vehicle. The housing may be a housing of a type commonly used in this field. A cell is a battery cell used to drive or operate an electric vehicle or other machinery or equipment, and a battery stack is typically formed by stacking multiple cells and connecting them in series. A battery pack according to this embodiment typically houses multiple stacks that are electrically connected in series or parallel, with the positive terminals of the stacks connected to their positive ends and the negative terminals connected to their negative ends being connected to the output terminals of the battery pack via busbars (total + busbar, total - busbar). The electrode terminals of multiple battery stacks are also connected via conductor members. The conductor members are conductors or conducting wires, and typically may be coated with an insulating coating except for the ends. The term "busbar" includes total + busbars, total - busbars, and busbars connected between stacks. Furthermore, the total + bus bar and total - bus bar may typically be connected to the output terminals of the battery pack via a junction box having a relay function.

[0009] In the battery pack configuration of the present invention, a "separating member" made of a shape memory alloy is disposed between the electrode terminals of the stack and conductive members such as bus bars, and the "separating member" is in a state that allows mechanical connection between the electrode terminals of the stack and the conductive members under normal temperature conditions, but deforms under temperatures exceeding a predetermined temperature, so as to break the mechanical connection between the electrode terminals of the stack and the conductive members and cut off electrical continuity between the electrode terminals and the conductive members. Here, the predetermined temperature is set by appropriately selecting a shape memory alloy, and may be set to a temperature that is determined to be abnormally high for the temperature inside the battery pack. According to this configuration, if the battery pack is subjected to an impact, for example, and generates heat due to an abnormal short circuit, or if the thermal diffusion phenomenon mentioned above occurs, the temperature inside the housing will rise, and in response to this, the separating member made of a shape memory alloy will deform, severing the mechanical connection between the electrode terminals of the stack and the conductor member, thereby interrupting electrical continuity between the electrode terminals and the conductor member, preventing the battery voltage from remaining applied to the conductor member and preventing the battery voltage from being transmitted to the surrounding area due to unexpected contact of the conductive parts of the conductor member. Furthermore, the configuration of the present invention is advantageous in that it only requires the separating member made of a shape memory alloy to be disposed between the electrode terminals of the stack and the conductor member as described above, thereby achieving a cut-off mechanism in the event of an abnormally high temperature in a smaller space than when a relay circuit element such as that used in a junction box is used.

[0010] In the above configuration, more specifically, the mechanical connection between the electrode terminals of the stack and the conductor members such as bus bars may be achieved by fastening the electrode terminals of the stack to the ends of the conductor members with bolts, and a separating member may cut the shanks of the bolts in an environment above a predetermined temperature, thereby separating the electrode terminals of the stack from the ends of the conductor members and releasing the mechanical connection. In this configuration, the separating member directly breaks the shanks of the bolts fastening the electrode terminals of the stack to the ends of the conductor members, thereby easily releasing the mechanical connection and electrical connection. The shanks of the bolts may be broken by pulling them in both axial directions, or by applying a shear force from the side of the shank to cut it in two. For ordinary bolts, the latter method is advantageous because it requires less force to cut them.

[0011] As another aspect of the above configuration, in an environment where the temperature exceeds a predetermined temperature, the separating member may cut the end of the conductor member, thereby breaking the mechanical connection between the electrode terminal of the stack and the conductor member.

[0012] The above-described configuration of the present invention, in which the separating member of the present invention is used to break the mechanical connection between the electrode terminals of the stack and conductive members such as bus bars, may be applied to any mechanical connection between the electrode terminals of the stack and conductive members within a battery pack, and may be particularly advantageously applied to the mechanical connection between the negative terminal of the battery stack and a general-busbar, which electrically connects the negative terminal of the battery stack to the output terminal of the battery pack and has a relatively long extension distance of the conductive member. This is advantageous in that, at abnormally high temperatures, the battery voltage is no longer applied to the general-busbar, which has a long extension distance, and therefore the battery voltage is not transmitted to the surroundings even if the general-busbar makes unexpected contact with the surroundings. [Effects of the Invention]

[0013] Thus, according to the configuration of the present invention, when the temperature inside the battery pack becomes abnormally high, the shape-memory alloy separating member deforms by utilizing the temperature change, thereby interrupting electrical continuity between the stack and conductive members such as bus bars. With this configuration, when the battery operation should be stopped due to abnormally high temperatures, the battery voltage is not applied to the conductive members extending relatively close to the housing. Therefore, even if the conductive members make unexpected contact with the surrounding area, the battery voltage is not transmitted to that contact, providing a higher level of safety. Furthermore, the configuration of the present invention is advantageous in that it does not require additional space for a relay circuit element and provides a mechanism for separating the connection between the stack and conductive members as compactly as possible. The battery pack of the present invention may be used in various electric vehicles and other machinery and devices that operate using battery power.

[0014] Other objects and advantages of the present invention will become apparent from the following description of preferred embodiments of the invention. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a schematic plan view of a stack of a battery pack to which this embodiment is applied, viewed from the surface direction. [Figure 2] 2(A) and 2(B) are schematic cross-sectional views of one aspect of a connection portion between an electrode terminal of a stack to which this embodiment is applied and a bus bar (conductor member), where (A) shows a state in which the electrode terminal of the stack and the end of the bus bar are mechanically connected, and (B) shows a state in which the electrode terminal of the stack and the end of the bus bar are separated. [Figure 3] 3A to 3C are schematic cross-sectional views of another example of a connection between an electrode terminal of a stack and a bus bar to which this embodiment is applied, where (A) shows a state in which the electrode terminal of the stack and the end of the bus bar are mechanically connected, (B) shows a state in which a separating member has cut the shank of a bolt fastening the electrode terminal of the stack and the end of the bus bar, and (C) shows a state in which the electrode terminal of the stack and the end of the bus bar have been separated. Fig. 3D is a schematic diagram of the shape of the tip of the separating member. [Figure 4] 4(A) to 4(C) are schematic cross-sectional views of still another embodiment of the connection portion between the electrode terminal and the bus bar of a stack to which this embodiment is applied, where (A) shows a state in which the electrode terminal of the stack and the end of the bus bar are mechanically connected, (B) shows a state in which the separating member has cut the end of the end of the bus bar, and (C) shows a state in which the cut bus bar has been separated from the electrode terminal of the stack. [Figure 5] FIG. 5 is a schematic cross-sectional view of a connection portion between an electrode terminal and a bus bar of a conventional stack. [Explanation of symbols]

[0016] 1...battery pack, 2...casing, 3...stack, 4+...positive terminal of stack, 4-...negative terminal of stack, 5+...total + bus bar (conductor member), 5-...total - bus bar (conductor member), 6...bus bar (conductor member), 7+, 7-...positive and negative junction boxes, 8+, 8-...conductor (conductor member), 9...output terminal, 10a...connection portion between total + bus bar and stack positive terminal, 10b...connection portion between total - bus bar and stack negative terminal, 11...connection portion between inter-stack bus bar and stack electrode terminal, 12...fastening bolt, 12a...bolt shank, 13...separation member, 13a...hole, 14...reducing portion, 15...cutting blade BEST MODE FOR CARRYING OUT THE INVENTION

[0017] The present invention will now be described in detail with reference to some preferred embodiments thereof with reference to the accompanying drawings, in which like reference numerals indicate like parts.

[0018] Basic structure of the battery pack housing 1 , in a battery pack 1 according to this embodiment that is installed in a machine or appliance such as an electric vehicle for driving or operating the machine or appliance, similar to conventional battery packs, multiple stacks 3 are arranged side by side in a housing 2, each consisting of multiple cells in a normal manner, and the positive terminal 4+ and negative terminal 4− of each stack 3 are electrically connected to the negative terminal 4− and positive terminal 4+ of another stack 3 by a bus bar or other conductor member 6. The multiple stacks 3 are connected in series (or in parallel), and the positive terminal 4+ of the stack 3 at the positive end is connected to an output terminal 9 via a common bus bar 5+, a junction box 7+, and a conductor or other conductor member 8+, and the negative terminal 4− of the stack 3 at the negative end of the multiple stacks 3 is connected to the output terminal 9 via a common bus bar 5−, a junction box 7−, and a conductor or other conductor member 8−, and electric power is transmitted from the output terminal 9 to an electric device DM such as a motor. As can be seen from the figure, among the multiple busbars or other conductor members, particularly the total-busbar 5-, the positive terminal 4+ at the positive end of the multiple stacks 3 and the negative terminal 4- at the negative end are typically located at the furthest positions. However, at the output terminal 9, the positive and negative conductors are extended in pairs, so either the total+ busbar 5+ or the total-busbar 5- must be located at a longer distance to the output terminal 9. In this case, since the negative potential is typically the ground potential, the positive terminal 4+ at the positive end of the multiple stacks 3 is located near the output terminal 9, making the total+ busbar 5+ short, and the negative terminal 4- at the negative end of the multiple stacks 3 far from the output terminal 9, making the total-busbar 5- long. The total-busbar 5- extends from the negative terminal 4- to the junction box 7- while being supported by an insulating support member 2a. The surface of the busbar 5 is typically covered with an insulating material except for its ends to prevent short-circuiting with the surroundings. Note that the surfaces of the other busbars may also be typically covered with an insulating material except for their ends to prevent short-circuiting with the surroundings.

[0019] Fail-safe configuration for high temperatures inside the enclosure With respect to battery pack 1 as shown in Figure 1, if the battery pack is subjected to an impact, for example, when the electric vehicle or other machinery and equipment on which it is mounted comes into contact with an obstacle, and a conductive part of one of the bus bars or other conductor parts comes into contact with an unexpected surrounding part, causing a short circuit, resulting in an excessive current flow, or thermal diffusion occurring in the cells, causing the temperature inside the housing to become abnormally high, or under other abnormal circumstances, the relay circuit is shut off as a fail-safe function in junction boxes 7+, 7-, and action is taken to cut off the continuity between output terminal 9 of the battery pack and stack 3, thereby stopping use of the battery pack. As a result, when an abnormality occurs in the battery pack, battery voltage will not be applied to the output terminal 9. In this regard, if the bus bars or other conductor members (5+, 5-, 6) remain mechanically connected to the electrode terminals (4+, 4-) of the stack 3 as shown in Figure 5, the battery voltage will remain applied to the conductor members (5+, 5-, 6), and if the conductive parts of the conductor members make unexpected contact with their surrounding areas in this state, the battery voltage will be transmitted to the unexpected surrounding areas. In particular, if the temperature inside the housing 2 becomes high, the insulating coating on the surface of the conductor members may be melted or removed, or may be deformed, which may cause unexpected contact between the conductor members and their surrounding areas.

[0020] Therefore, in this embodiment, when the temperature inside the housing 2 becomes abnormally high, the mechanical connection between the conductor members (5+, 5-, 6) and the electrode terminals (4+, 4-) of the stack 3 is broken, interrupting the conduction therebetween and preventing the application of battery voltage to the conductor members. As such a configuration, in this embodiment, as described in the "Summary of the Invention" section, a "separating member" made of a shape memory alloy that deforms in an environment above a predetermined temperature is in a state that allows the mechanical connection between the electrode terminals of the stack and the conductor members in a normal temperature environment below the predetermined temperature, and is arranged to deform in an environment above the predetermined temperature, breaking the mechanical connection between the electrode terminals of the stack and the conductor members and interrupting the electrical conduction between the electrode terminals and the conductor members. With this configuration, if the temperature inside the housing 2 exceeds a predetermined temperature due to the generation of excessive current in the battery pack 1 or the thermal diffusion phenomenon of the cells, the separating member will deform in response to this temperature rise, thus breaking the mechanical connection between the electrode terminals of the stack and the conductor member, interrupting electrical conduction between the electrode terminals and the conductor member, and preventing the battery voltage from being transmitted to the conductor member.

[0021] In one embodiment, a configuration for breaking the mechanical connection between conductor members such as bus bars and electrode terminals of a stack using a "separating member" made of a shape memory alloy is shown, as schematically illustrated in Figures 2(A) and (B), in which the ends of the conductor members (5+, 5-, 6) are in contact with the electrode terminals (4+, 4-) of the stack 3, and the shanks 12a of the bolts 12 are inserted through the conductor members (5+, 5-, 6) and the electrode terminals (4+, 4-) to fasten them together. In this configuration, a separating member 13 made of a shape memory alloy is disposed between the conductor members (5+, 5-, 6) and the electrode terminals (4+, 4-), which expands in a direction (arrow X in the figure) to separate the conductor members (5+, 5-, 6) from the electrode terminals (4+, 4-) when a predetermined temperature is exceeded. If the temperature inside the housing 2 becomes abnormally high, the separating member 13 deforms from the state shown in FIG. 2(A) to the state shown in FIG. 2(B), displacing the conductor members (5+, 5-, 6) away from the electrode terminals (4+, 4-). This causes the shank 12a of the bolt 12 to be pulled axially and break, separating the conductor members (5+, 5-, 6) from the electrode terminals (4+, 4-). (Note that an insulating layer is interposed between at least one of the interfaces between the conductor members and the separating member 13 and between the electrode terminals (4+, 4-) and the separating member 13, thereby interrupting electrical continuity through the separating member 13.) In this configuration, after the bolt breaks, a new bolt can be used to connect the conductor members and the electrode terminals. (In some cases, it may not be necessary to replace the conductor members and electrode terminals.)

[0022] In another embodiment of the configuration for breaking the mechanical connection between the conductor members and the electrode terminals of the stack using a separating member, as schematically illustrated in Figures 3(A) to (C), in a configuration in which the shanks 12a of the bolts 12 are inserted through the conductor members (5+, 5-, 6) and the electrode terminals (4+, 4-) to fasten them together with the ends of the conductor members (5+, 5-, 6) in contact with the electrode terminals (4+, 4-) of the stack 3, a mechanism may be provided in which, when a predetermined temperature is exceeded between the electrode terminals (4+, 4-) and the conductor members (5+, 5-, 6), the separating member 13 applies a shear force from the side to the shank 12a of the bolt 12 to cut it off. Specifically, as shown in Fig. 3(A), holes 13a are drilled in advance in the conductor members (5+, 5-, 6) so as to intersect with the screw holes in the shanks 12a, and a separating member 13, which has a cutting blade at its tip and expands when the temperature exceeds a predetermined value, as shown in Fig. 3(D), is inserted into the hole 13a outside the shank 12a with its tip facing the shank 12a, and the opposite end of the separating member 13 is brought into contact with the electrode terminals (4+, 4-). Then, as shown in Fig. 3(B), when the temperature inside the housing becomes abnormally high, the separating member 13 expands within the hole 13a, and its tip applies a shear force to the shank 12a, cutting it off. 3(C), the conductor members (5+, 5-, 6) are separated from the electrode terminals (4+, 4-) together with the upper part of the shaft portion 12a and the separating member 13, and the electrical continuity between the conductor members and the electrode terminals is cut off. In this case, too, after the bolt breaks, it is possible to use a new bolt to connect the conductor members and the electrode terminals. (There are cases where it is not necessary to replace the conductor members and the electrode terminals.)

[0023] In yet another embodiment of the configuration for breaking the mechanical connection between the busbar and the electrode terminals of the stack using a separating member, as schematically illustrated in Figures 4(A) to (C), in a configuration in which the ends of the conductor members (5+, 5-, 6) are in contact with the electrode terminals (4+, 4-) of the stack 3, and the shanks 12a of the bolts 12 are inserted through the conductor members (5+, 5-, 6) and the electrode terminals (4+, 4-) to fasten them together, a mechanism may be provided in which a portion of the conductor member is made thinner (reduced portion 14), and when the temperature exceeds a predetermined temperature, the separating member 13 deforms to cut off the reduced portion 14 of the conductor member. Specifically, as shown in FIG. 4(A), tip 15 of separating member 13, which expands when the temperature exceeds a predetermined level, is brought into contact with reduced portions 14 of conductor members (5+, 5-, 6), and when the temperature inside the housing becomes abnormally high, separating member 13 expands as shown in FIG. 4(B), and tip 15 cuts reduced portions 14 of the conductor members. Thus, as shown in FIG. 4(C), conductor members (5+, 5-, 6) are separated from electrode terminals (4+, 4-), leaving only their ends, and electrical continuity between the conductor members and the electrode terminals is interrupted.

[0024] In the above series of configurations, the separating member 13 may be formed from any shape memory alloy available for this purpose, such as a nickel-titanium alloy, etc. The temperature at which the separating member 13 deforms and cuts off the bolt shank may be set to, for example, several hundred degrees Celsius.

[0025] The above-mentioned configuration for breaking the mechanical connection between the conductor member and the electrode terminal of the stack may require a certain degree of specific structure to be formed in the conductor member depending on the embodiment, but can basically be achieved by interposing a separation member made of a shape memory alloy between the conductor member and the electrode terminal, which is advantageous in that it can be achieved in a smaller space than when, for example, an additional relay circuit element is provided between the conductor member and the electrode terminal.

[0026] In the configuration of the present embodiment, a heater capable of raising the temperature instantaneously (for example, within 0.07 seconds) may be incorporated into the separating member to ensure deformation of the separating member. In this case, the conductive member and the electrode terminal of the stack can be separated without waiting for the temperature inside the housing to rise.

[0027] The above-described configuration for breaking the mechanical connection between the conductor member and the electrode terminal of the stack using a separating member may be applied to any of the connection portions 10a, 10b, and 11 between the conductor member in the battery pack and the electrode terminal of the stack. In particular, if the configuration of this embodiment is applied to the general-busbar 5, which has a long conductor member extension, it is possible to significantly reduce the chance of the battery voltage being transmitted to unexpected locations due to unexpected contact of the conductive portion of the general-busbar with its surrounding locations.

[0028] Although the above description has been made in relation to the embodiments of the present invention, it will be apparent that many modifications and changes can be easily made by those skilled in the art, and the present invention is not limited to the above-described exemplary embodiments, but can be applied to various devices without departing from the concept of the present invention.

Claims

1. A battery pack that houses a battery stack including a plurality of cells within a housing and a conductor member that is mechanically connected to the electrode terminals of the stack and thereby electrically conductive, wherein a separating member made of a shape memory alloy that deforms in an environment above a predetermined temperature is disposed between the electrode terminals of the stack and the conductor member so that the separating member allows the mechanical connection between the electrode terminals of the stack and the conductor member in an environment below the predetermined temperature, and deforms in an environment above the predetermined temperature, thereby breaking the mechanical connection between the electrode terminals of the stack and the conductor member and interrupting electrical conduction between the electrode terminals and the conductor member.

2. 2. The battery pack of claim 1, wherein the conductor member is a general-bus bar that electrically connects a negative terminal of the battery stack and an output terminal of the battery pack, and the mechanical connection between the electrode terminal of the stack and the bus bar is a mechanical connection between the general-bus bar and the negative terminal of the battery stack.

3. 2. The battery pack of claim 1, wherein the mechanical connection between the electrode terminal of the stack and the conductor member is achieved by fastening the electrode terminal of the stack and the end of the conductor member together with a bolt, and the separating member cuts off the shank of the bolt in an environment above the predetermined temperature, thereby separating the electrode terminal of the stack and the end of the conductor member and severing the mechanical connection.

4. 4. The battery pack of claim 3, wherein the separating member is arranged to apply a shear force to the shank of the bolt from the side in an environment where the temperature exceeds the predetermined temperature, thereby cutting off the shank of the bolt.

5. 2. The battery pack according to claim 1, wherein the separating member cuts the end of the conductive member in an environment where the temperature exceeds the predetermined temperature, thereby breaking the mechanical connection.

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