Busbar structure

Abstract

To obtain bus bar structure which when heat generation of a bus bar subsides, can measure voltage again without replacing or repairing a voltage detection portion.SOLUTION: A bus bar structure 10 comprises: a bus bar 12 which connects a plurality of batteries; a voltage detection portion 14 which is provided on the bus bar 12 and detects voltage of each battery; a first member 16 in which the one end thereof is fixed to the voltage detection portion 14; a second member 18 which is arranged outside the first member 16, and in which the one end thereof is fixed to the bus bar 12; an elastic member 40 which is interposed between the first member 16 and the second member 18; and an expansion contraction member 42 which is interposed between the first member 16 and the bus bar 12, and expands and contracts so that the voltage detection portion 14 and the bus bar 12 come in contact with each other when the temperature of the bus bar is less than a predetermined temperature.SELECTED DRAWING: Figure 2

Description

[[Technical Field]]

[0001] The present disclosure relates to a bus bar structure connecting a plurality of batteries. [[Background Art]]

[0002] Patent Document 1 discloses a bus bar structure in which, in order to enable early detection of abnormal heat generation in a bus bar, the melting point of a fixing claw provided on a resin frame for fixing a voltage detection line terminal to the bus bar is set lower than the melting point of the resin frame, so that when abnormal heat generation occurs, the fixing claw melts before the resin frame melts, and the voltage detection line terminal is detached from the bus bar. [[Prior Art Literature]] [[Patent Literature]]

[0003] [[Patent Document 1]] Japanese Unexamined Patent Publication No. 2012-089343 [[Summary of the Invention]] [[Problem to be Solved by the Invention]]

[0004] In the bus bar structure described in Patent Document 1, once the fixing claw melts and the bus bar is detached from the voltage detection line terminal, voltage detection cannot be performed until the voltage detection line terminal is fixed to the bus bar by a new fixing claw. Therefore, even when the heat generation of the bus bar at a temperature equal to or higher than the predetermined temperature is temporary, it becomes necessary to replace or repair the fixing claw.

[0005] The present disclosure has been made in view of the above circumstances, and an object of the present disclosure is to provide a bus bar structure capable of measuring voltage again without replacing or repairing parts when the heat generation of the bus bar subsides. [[Means for Solving the Problem]]

[0006] The busbar structure according to claim 1 comprises a busbar connecting a plurality of batteries, a voltage detection unit provided on the busbar for detecting the voltage of the batteries, a first member with one end fixed to the voltage detection unit, a second member disposed outside the first member and with one end fixed to the busbar, an elastic member interposed between the first member and the second member, and an elastic member interposed between the first member and the busbar that expands and contracts to bring the voltage detection unit and the busbar into contact when the temperature is below a predetermined temperature. Furthermore, when the temperature exceeds the predetermined temperature, the voltage detection unit and the busbar expand and contract so as to separate. It comprises an expandable and contractible member.

[0007] In the busbar structure according to claim 1 of the present invention, the expandable / contractible member interposed between the first member and the busbar expands and contracts when the temperature is below a predetermined temperature so that the voltage detection unit and the busbar come into contact. In other words, when the temperature is above the predetermined temperature, the expandable / contractible member expands and contracts so that the voltage detection unit and the busbar separate. That is, when the expandable / contractible member expands when the temperature is above the predetermined temperature, the expandable / contractible member pushes up the first member against the biasing force of the elastic member, so the voltage detection unit fixed to the first member is also pushed up and the voltage detection unit and the busbar separate.

[0008] Then, when the expansion / contraction member falls from above a predetermined temperature to below that temperature, the expansion / contraction member contracts, and the biasing force of the elastic member pushes down the first member. As a result, the voltage detection unit fixed to the first member is pushed down, and the voltage detection unit comes into contact with the busbar. In this way, the voltage detection unit and the busbar come into contact only when the temperature is below the predetermined temperature. This allows the voltage to be measured again without replacing or repairing any parts once the heat generated by the busbar above the predetermined temperature has subsided.

[0009] The busbar structure according to claim 2 is the configuration according to claim 1, wherein the expansion and contraction member is made of a shape memory alloy.

[0010] In the busbar structure according to claim 2, since the expansion and contraction member is made of a shape memory alloy, the thermal conductivity of the expansion and contraction member is good, and the heat generated by the busbar can be detected in a short period of time.

[0011] The busbar structure according to claim 3 is the configuration according to claim 1 or claim 2, wherein the expansion and contraction member is fixed to the busbar using a thermally conductive adhesive.

[0012] In the busbar structure according to claim 3, the expansion / contraction member is fixed to the busbar using a thermally conductive adhesive, so that the heat generated by the busbar can be transferred more quickly to the expansion / contraction member via the adhesive. Furthermore, if the expansion / contraction member is formed of a spring member, the contact area between the busbar and the expansion / contraction member, which tends to be small due to the adhesive, can be improved, thus increasing the heat transfer area.

[0013] The busbar structure according to claim 4 is the configuration according to claim 1, wherein the expansion / contraction member contains a liquid that vaporizes when the temperature is above the predetermined temperature, and is formed of a material that can expand by internal pressure, at least a portion of which is contained within.

[0014] In the busbar structure according to claim 4, the expandable / contractable member contains a liquid that vaporizes when the temperature is above a predetermined level, and at least a portion of it is made of a material that can expand due to internal pressure. Therefore, when the temperature rises above the predetermined level, the liquid vaporizes and the internal pressure increases, causing the portion made of the expandable material to expand and push up the first member.

[0015] The busbar structure according to claim 5 is the configuration according to any one of claims 1 to 4, wherein the first member is formed to be slidable along the inner wall of the second member.

[0016] In the busbar structure according to the present invention set forth in claim 5, the first member is formed slidably along the inner wall of the second member, so that the first member can move along the inner wall of the second member when the first member is pushed up, thereby making it easier to maintain the horizontal state of the first member. Therefore, the voltage detection unit fixed to the first member can also be moved while maintaining its horizontal state, whereby the detection accuracy of the voltage detection unit can be improved. [Effects of the Invention]

[0017] With the busbar structure according to the present invention, when the heat generation of the busbar subsides, voltage can be measured again without replacing or repairing parts. [Brief Description of the Drawings]

[0018] [Figure 1] FIG. 1 is a schematic plan view showing the configuration of a battery module according to an embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view taken along line A-A in FIG. 1, showing the expandable / contractible member of the busbar structure according to the first embodiment of the present invention in a contracted state. [Figure 3] FIG. 3 is a cross-sectional view taken along line A-A in FIG. 1, showing the expandable / contractible member of the busbar structure according to the first embodiment of the present invention in an expanded state. [Figure 4] FIG. 4 is a graph showing changes in temperature, load and voltage over time. [Figure 5] FIG. 5 is a flowchart showing a series of control processes for heat generation detection in a busbar structure. [Figure 6] FIG. 6 is a cross-sectional view corresponding to FIG. 2, showing the expandable / contractible member of the busbar structure according to the second embodiment of the present invention in a contracted state. [Figure 7] FIG. 7 is a cross-sectional view corresponding to FIG. 2, showing the expandable / contractible member of the busbar structure according to the third embodiment of the present invention in a contracted state. [Figure 8] FIG. 8 is a top view of the expandable / contractible member of FIG. 7. [Figure 9] FIG. 9 is a cross-sectional view taken along line D-D in FIG. 8. [Figure 10]It is a cross-sectional view of the expansion / shrinkage member in an expanded state corresponding to FIG. 3 in the busbar structure according to the third embodiment of the present invention. [Figure 11] It is a flowchart showing a series of control processes for heat generation detection in a conventional busbar structure. Mode for Carrying Out the Invention

[0019] (First Embodiment) Hereinafter, the busbar structure 10 according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 5. In the description of the drawings, the same reference numerals are used for identical or equivalent elements, and duplicate descriptions are omitted.

[0020] FIG. 1 is a schematic plan view showing the configuration of a battery module 1 according to an embodiment of the present invention. The battery module 1 is mounted, for example, on various vehicles such as forklifts, hybrid vehicles, and electric vehicles.

[0021] As shown in FIG. 1, the battery module 1 includes a plurality of cells 20 as secondary batteries (batteries), a busbar structure 10 including a plurality of busbars 12 and a plurality of voltage detection units 14, and a conductive member 30. As an example, the battery module 1 of the present embodiment includes four cells 20, three busbars 12, and four voltage detection units 14. The four cells 20 are arranged side by side in one direction. An example of the cell 20 is a lithium ion battery.

[0022] Each cell 20 includes a housing 22 and a pair of external terminals 24. The housing 22 is formed in a substantially flat, substantially rectangular parallelepiped shape. Of the pair of external terminals 24, the one shown colored is a positive electrode terminal, and the other is a negative electrode terminal. In the present embodiment, the two cells 20 shown on the upper side of the drawing in FIG. 1 have the positive electrode terminal arranged on the right side and the negative electrode terminal arranged on the left side. Conversely, the two cells 20 shown on the lower side of the drawing have the positive electrode terminal arranged on the left side and the negative electrode terminal arranged on the right side. The pair of external terminals 24 are arranged on the flat surface on the outer side (the upper side in the present embodiment) of the housing 22, and are disposed so as to face the outside.

[0023] The busbar 12 is formed in a flat shape and electrically connects adjacent cells 20 in one direction. Specifically, it electrically connects the external terminals 24 of adjacent cells 20. In this embodiment, as shown in Figure 1, on the left side, one busbar 12 electrically connects the two negative terminals and two positive terminals, which are the external terminals 24 of four cells 20. On the other hand, on the right side, one of the two busbars 12 (the upper busbar) electrically connects the two positive terminals, which are the external terminals 24 of two adjacent cells 20, while the other busbar 12 (the lower busbar) electrically connects the two negative terminals, which are the external terminals 24 of the remaining two adjacent cells 20. Here, the white arrows in Figure 1 indicate the flow of current.

[0024] The voltage detection unit 14 measures the voltage of each cell 20. A known voltmeter can be used for the voltage detection unit 14. Each voltage detection unit 14 is connected to an ECU (Electronic Control Unit) via a wire 14A. Although only the voltage detection unit 14 is shown in Figure 1, in practice, there are also components included in the busbar structure 10, which will be described in detail later.

[0025] The conductive member 30 is arranged to be in contact with each cell 20, and in this embodiment, the conductive member 30 is positioned to be in contact with the lower surface of each cell 20. The conductive member 30 has a cooling function for cooling the cells 20. In this embodiment, as an example, the conductive member 30 is composed of a cooler, but the present invention is not limited to this, and the conductive member 30 may be composed of a different material from the cooler.

[0026] Although not shown in the diagram, separators made of an insulator such as resin may be placed between adjacent cells 20.

[0027] Next, the busbar structure 10 will be described. As shown in Figure 2, the busbar structure 10 includes a busbar 12, a voltage detection unit 14, a first member 16, a second member 18, an elastic member 40, and an expandable / contractable member 42. The voltage detection unit 14 is provided on the busbar 12.

[0028] The first component 16 is a resin structure, and for example comprises a cylindrical main body 16A and a substantially circular flange 16B that protrudes outward from the outer circumferential surface approximately in the center of the main body 16A in the vertical direction. The lower end of the main body 16A is fixed to the upper surface of the voltage detection unit 14.

[0029] The second member 18 is disposed on the outside of the first member 16 and, as an example, comprises a cylindrical portion 18A formed in a cylindrical shape and a disc portion 18B that protrudes substantially horizontally inward from the upper end of the cylindrical portion 18A and has an opening in the center. The electric wire 14A is taken out from this opening and connected to the ECU. The lower end of the cylindrical portion 18A is fixed to the upper surface of the busbar 12.

[0030] In this embodiment, the first member 16 is configured to slide along the inner wall of the second member 18. Specifically, the side end surface of the flange portion 16B of the first member 16 is configured to slide vertically along the inner wall of the cylindrical portion 18A of the second member 18. In Figures 2 and 3, the side end surface of the flange portion 16B and the inner wall of the cylindrical portion 18A are spaced apart, but in reality, they are in contact to the extent that sliding is possible.

[0031] The elastic member 40 is, for example, composed of a spring member and is interposed between the first member 16 and the second member 18. Specifically, the elastic member 40 is composed of a substantially cylindrical spring member, is positioned inside the second member 18, and is arranged to surround the upper end of the flange portion 16B of the first member 16. The lower end of the elastic member 40 abuts against the upper surface of the flange portion 16B of the first member 16, and the upper end abuts against the lower surface of the disc portion 18B of the second member 18. The elastic member 40 biases the first member 16 downward, i.e., towards the busbar 12.

[0032] The expansion / contraction member 42 is made of a shape memory alloy and, as an example, is formed as a substantially cylindrical spring member. The expansion / contraction member 42 is interposed between the first member 16 and the busbar 12. Specifically, the expansion / contraction member 42 is positioned below the flange portion 16B of the first member 16, and its lower end is fixed to the busbar 12. In this embodiment, as an example, the expansion / contraction member 42 is fixed to the upper surface of the busbar 12 using a thermally conductive adhesive 44.

[0033] When the expansion / contraction member 42 is below a predetermined temperature, its spring force is weak, so it is pressed by the biasing force of the elastic member 40, causing its length in the vertical direction (axial direction) to contract. In this embodiment, the predetermined temperature is the deformation temperature at which the shape memory alloy deforms.

[0034] On the other hand, when the temperature exceeds a predetermined temperature, the spring force of the expansion / contraction member 42 becomes stronger compared to when the temperature is below the predetermined temperature. As a result, the expansion / contraction member 42 returns to its original shape due to the reaction force of the expansion / contraction member 42, which is contrary to the biasing force of the elastic member 40. In other words, the expansion / contraction member 42 expands in length in the vertical direction (axial direction). Furthermore, when the temperature falls below the predetermined temperature while the expansion / contraction member 42 is in an expanded state, the spring force weakens, and it is pressed by the biasing force of the elastic member 40, causing it to contract in length in the vertical direction (axial direction).

[0035] As shown in Figure 4(A), for example, if the temperature of the expandable / contractable member 42 rises over time, as shown in Figure 4(B), the load indicating the reaction force of the expandable / contractable member 42 begins to rise from time C when it reaches a predetermined temperature B. When the load indicating the reaction force of the expandable / contractable member 42 becomes greater than the load D, which is the load that biases the elastic member 40 toward the busbar 12 (to the right of the load indicated by arrow E in Figure 3), at time F when load D < reaction force, the expandable / contractable member 42 begins to expand in length in the vertical direction (axial direction), as shown in Figure 3, and begins to push up the flange portion 16B of the first member 16.

[0036] When the flange portion 16B is pushed up, the first member 16 is also pushed up, so the voltage detection unit 14 fixed to the first member 16 also begins to move upward and starts to move away from the bus bar 12. When the voltage detection unit 14 is completely separated from the bus bar 12, the voltage detected by the voltage detection unit 14 becomes 0V, as shown by arrow G, as shown in Figure 4(C).

[0037] On the other hand, when the temperature of the expandable / contractible member 42, shown in Figure 3, drops below a predetermined temperature from its expanded state, the load D, which is the biasing force of the elastic member 40 toward the busbar 12, becomes larger than the load indicating the reaction force of the expandable / contractible member 42 (to the left of the load indicated by arrow E in Figure 3). As a result, the expandable / contractible member 42 is pressed by the biasing force of the elastic member 40, and its length in the vertical direction (axial direction) begins to contract, pushing down the first member 16 as well. Consequently, the voltage detection unit 14 fixed to the first member 16 also begins to move downward, and as shown in Figure 2, the expandable / contractible member 42 separates from the flange portion 16B of the first member 16, and the voltage detection unit 14 comes into contact with the busbar 12. When the voltage detection unit 14 comes into contact with the busbar 12, the voltage detected by the voltage detection unit 14 becomes greater than 0V.

[0038] Next, a series of control methods for heat detection in the busbar structure 10 will be described. As shown in Figure 5, first, in step S11, the ECU 32 acquires the voltage value between cells 20 output from the voltage detection unit 14 via the wire 14A. In step S12, the ECU 32 determines whether the acquired voltage value is greater than a predetermined threshold. In this embodiment, the threshold is set to "0" as an example.

[0039] In step S12, if the acquired voltage value is greater than the threshold (step S12; YES), the ECU32 returns to step S11 and proceeds with the processing from step S11 onwards. On the other hand, in step S12, if the acquired voltage value is less than or equal to the threshold (step S12; NO), in step S13, the ECU32 determines that an abnormality has occurred between the cells 20.

[0040] Normally, if an abnormality occurs in a cell 20 arranged in parallel, the resistance of the busbar 12 connected to the abnormal cell 20 becomes higher than when no abnormality occurs. As a result, a larger current flows from the side with higher resistance to the side with lower resistance due to the resistance difference, causing the temperature of the busbar 12 to become higher than expected. When the temperature of the busbar 12 becomes high, heat is conducted to the expandable / contractable member 42 fixed to the upper surface of the busbar 12 using a thermally conductive adhesive 44, causing the temperature of the expandable / contractable member 42 to also rise.

[0041] When the temperature of the expansion / contraction member 42 exceeds a predetermined temperature, the expansion / contraction member 42 returns to its original shape against the biasing force of the elastic member 40, as described above, and its vertical length expands, pushing up the flange portion 16B of the first member 16. As a result, the first member 16 floats up, and the voltage detection unit 14 fixed to the first member 16 also floats up, causing the voltage output by the voltage detection unit 14 to become 0V. In this way, with the above structure, a high-temperature state caused by an abnormality in the cell 20 can be detected as a change in voltage.

[0042] Then, when the voltage value acquired by the ECU32 becomes 0V (threshold), the ECU32 determines in step S13 that an abnormality has occurred between the busbar 12, i.e., between the cells 20. Therefore, in step S14, the ECU32 intervenes in the protection control of the battery module 1 and executes the escape driving mode. The escape driving mode includes output limiting of the power output from the battery module. Then, the ECU32 returns to step S11 and proceeds with the processing from step S11 onwards.

[0043] Next, the effects and advantages of the busbar structure 10 in the first embodiment will be described.

[0044] In the busbar structure 10 according to the first embodiment, the expandable / contractible member 42 interposed between the first member 16 and the busbar 12 expands and contracts when the temperature is below a predetermined temperature so that the voltage detection unit 14 and the busbar 12 come into contact. In other words, when the temperature is above the predetermined temperature, the expandable / contractible member 42 expands and contracts so that the voltage detection unit 14 and the busbar 12 separate. That is, when the expandable / contractible member 42 expands when the temperature is above the predetermined temperature, the expandable / contractible member 42 pushes up the first member 16 against the biasing force of the elastic member 40, so the voltage detection unit 14 fixed to the first member 16 is also pushed up and the voltage detection unit 14 and the busbar 12 separate.

[0045] Then, when the expansion / contraction member 42 falls from above a predetermined temperature to below a predetermined temperature, the expansion / contraction member 42 contracts, and the biasing force of the elastic member 40 pushes down the first member 16. As a result, the voltage detection unit 14 fixed to the first member 16 is pushed down, and the voltage detection unit 14 comes into contact with the busbar 12. In this way, the voltage detection unit 14 and the busbar 12 come into contact only when the temperature is below the predetermined temperature. This allows the voltage to be measured again without replacing or repairing any parts once the heat generation of the busbar 12 above the predetermined temperature has subsided.

[0046] Furthermore, in the busbar structure 10 according to the first embodiment, since the expansion and contraction member 42 is made of a shape memory alloy, the thermal conductivity of the expansion and contraction member 42 is good, and the heat generated by the busbar can be detected in a short period of time.

[0047] Furthermore, in the busbar structure 10 according to the first embodiment, the expansion / contraction member 42 is fixed to the busbar 12 using a thermally conductive adhesive 44, so that the heat generated by the busbar 12 can be quickly transferred to the expansion / contraction member 42 via the adhesive 44. In addition, since the expansion / contraction member 42 is formed of a spring member, the contact area between the busbar 12 and the expansion / contraction member 42, which tends to be small due to the adhesive 44, can be improved, thus increasing the heat transfer area.

[0048] Furthermore, in the busbar structure 10 according to the first embodiment, the first member 16 is formed to slide along the inner wall of the second member 18. Therefore, when the first member 16 is pushed up, it can move along the inner wall of the second member 18, making it easier to maintain the horizontal position of the first member 16. As a result, the voltage detection unit 14 fixed to the first member 16 can also move while maintaining its horizontal position, thereby improving the detection accuracy of the voltage detection unit 14.

[0049] Furthermore, in the busbar structure 10 according to the first embodiment, when detecting heat generation, the high-temperature state caused by an abnormality in the cell 20 can be captured as a change in voltage. Here, a conventional busbar structure will be described. Figure 11 is a flowchart showing a series of control processes for heat generation detection in a conventional busbar structure. In the conventional busbar structure, as shown in Figure 11, first, in step 21, the ECU acquires the cell voltage value output by the voltage detection unit, and in step S22, it also acquires the current value. Furthermore, in step S23, the ECU acquires the IV characteristics by plotting the acquired voltage and current values ​​and calculates the resistance value. In step S24, the ECU determines whether the calculated resistance value is below a predetermined threshold, and if it is below the threshold (step S24; YES), the ECU returns to step S21 and proceeds to the processing from step S21 onwards.

[0050] On the other hand, if the acquired resistance value in step S24 is greater than the threshold (step S24; NO), in step 25, the number of times the resistance value has been greater than the threshold, i.e., the number of resistance abnormalities, is counted up. In step S26, the ECU determines whether the count is greater than or equal to a predetermined threshold. If the count is less than the threshold (step S26; NO), the ECU returns to step S21 and proceeds to the processing from step S21 onward.

[0051] On the other hand, in step S26, if the count is greater than or equal to the threshold (step S26; YES), the ECU intervenes in the battery module's protection control to execute the escape driving mode. Then, the ECU returns to step S21 and proceeds with the processing from step S21 onward.

[0052] Thus, in conventional busbar structures, resistance values ​​are calculated, and since it takes about 30 seconds to calculate each resistance value, it is time-consuming to calculate a single resistance value. Furthermore, to avoid false positives, an abnormality is determined to have occurred between cells only when the resistance value exceeds a threshold multiple times, for example, three times, and this abnormality determination process takes about 60 to 90 seconds.

[0053] In contrast to the conventional busbar structure, the busbar structure 10 of the first embodiment determines whether or not an abnormality has occurred between the cells 20 simply by determining the voltage value output from the voltage detection unit 14, thus shortening the time required for abnormality detection compared to the conventional method.

[0054] Furthermore, since there is no need to add new sensors, such as equipment for detecting current values, costs can be reduced. For example, it is possible to provide a temperature sensor to detect the temperature of the busbar 12 and bring the busbar 12 into contact with or separate from the voltage detection unit 14 according to the output from the temperature sensor, but in this case, the cost of mounting the temperature sensor and the mounting means will be incurred, increasing the overall cost. In this embodiment, the voltage detection unit 14 that is already installed can be utilized, thus reducing costs.

[0055] In the above embodiment, the expansion / contraction member 42 was a spring member made of a shape memory alloy, but the present invention is not limited thereto. Other embodiments of the expansion / contraction member will be described below. Regarding the busbar structure on which the expansion / contraction member is mounted, components similar to those in the first embodiment described above are indicated by the same reference numerals and their description is omitted, and only the different parts will be described in detail.

[0056] (Second Embodiment) The expansion and contraction member 46 mounted on the busbar structure 10A according to the second embodiment of the present invention will now be described with reference to Figure 6. As shown in Figure 6, the expansion and contraction member 46 of the second embodiment comprises a spring 46A made of shape memory alloy and a substantially disc-shaped flat plate member 46B made of shape memory alloy. The spring 46A has the same configuration as the expansion and contraction member 42 of the first embodiment. The flat plate member 46B is fixed to the upper surface of the busbar 12 using a thermally conductive adhesive 44. The spring 46A is also fixed to the upper surface of the flat plate member 46B using a thermally conductive adhesive 44.

[0057] Even when the expansion / contraction member 46 of the second embodiment is composed of two members, the same effects as when the expansion / contraction member 42 of the first embodiment is used can be obtained.

[0058] (Third embodiment) The following describes the expansion and contraction member 50 mounted on the busbar structure 10B according to the third embodiment of the present invention, with reference to Figures 7 to 10. The expansion and contraction member 50 of the third embodiment comprises a case portion 52 and a lid portion 54, as shown in Figures 7 to 9. The case portion 52 is formed as a cylindrical box with an open top and is made of a material having sufficient rigidity to not deform due to internal pressure, which will be described later.

[0059] The lid portion 54 covers the upper part of the case portion 52 and is formed in the shape of a disc with an opening in the center, as shown in Figure 8. It is made of a material that can be deformed (expanded) in the vertical direction (axial direction) by the internal pressure described later.

[0060] The case 52 contains a liquid 60 that vaporizes when the temperature is above a predetermined level. Here, the predetermined level is set to the boiling point of the liquid 60. The liquid 60 is of a type whose boiling point corresponds to the temperature of the busbar 12 when an abnormality is determined to have occurred in the cell 20.

[0061] With the lid portion 54 attached to the upper part of the case portion 52, the expansion and contraction member 50 expands vertically due to the internal pressure rising as the liquid 60 vaporizes, as shown in Figure 10.

[0062] In other words, below a predetermined temperature, the internal pressure of the expansion / contraction member 50 does not rise, so the first member 16 is pressed by the biasing force of the elastic member 40, and the voltage detection unit 14 fixed to the first member 16 comes into contact with the busbar 12.

[0063] On the other hand, when the temperature of the busbar 12 rises and the temperature of the liquid 16 rises above a predetermined temperature, the internal pressure increases compared to when the temperature is below the predetermined temperature, causing the lid 54 to deform (expand) in the vertical direction (axial direction). As shown in Figure 10, the expansion of the lid 54 pushes up the first member 16 against the biasing force of the elastic member 40, so the voltage detection unit 14 fixed to the first member 16 is also pushed up and the voltage detection unit 14 separates from the busbar 12.

[0064] On the other hand, when the temperature of the liquid 60 inside the expandable / contractible member 50, shown in Figure 10, drops below a predetermined temperature from an expanded state, the internal pressure decreases compared to when the temperature is above the predetermined temperature. As a result, the deformation (expansion) of the lid portion 54 contracts and returns to its original state. That is, as shown in Figure 7, the contraction of the lid portion 54 pushes down the first member 16 due to the biasing force of the elastic member 40, so the voltage detection unit 14 fixed to the first member 16 is also pushed down and the voltage detection unit 14 comes into contact with the busbar 12.

[0065] Even when using the expansion and contraction member 50 of the third embodiment, which utilizes the increase and decrease of internal pressure due to the vaporization of the liquid 60 contained inside, the same effects as when using the expansion and contraction member 42 of the first embodiment can be obtained.

[0066] [remarks] In the embodiments described above, the main body portion 16A of the first member 16 and the cylindrical portion 18A of the second member 18 are cylindrical, but the present invention is not limited to this, and they may be polygonal or cylindrical, or can be modified as appropriate.

[0067] Furthermore, although the flange portion 16B of the first member 16 is disc-shaped in the above-described embodiment, the present invention is not limited thereto. As long as the expansion and contraction member can make contact with it, the structure may, for example, have multiple outwardly protruding protrusions, and the shape is not particularly limited.

[0068] Furthermore, in the embodiments described above, the battery module 1 has a structure in which the cells 20 are arranged in parallel, but the present invention is not limited to this. For example, the cells 20 may be arranged in series.

[0069] Furthermore, in the first and second embodiments described above, the expansion and contraction members 42 and 46 are fixed to the busbar 12 using a thermally conductive adhesive, but the present invention is not limited thereto. They may be fixed by known techniques other than adhesives.

[0070] Furthermore, the configuration of the present invention is not limited to the above-described embodiments, and the configuration can be modified as appropriate, as long as the problem can be solved. [Explanation of Symbols]

[0071] 10, 10A, 10B busbar structure, 12 busbars, 14 voltage detection unit, 16 First component, 18 Second component, 20 Cell (battery), 40 Elastic component, 42, 46, 50 Expandable and contractible material, 44 Adhesive, 60 Liquid

Claims

1. A busbar that connects multiple batteries, A voltage detection unit is provided on the busbar to detect the voltage of the battery, A first member, one end of which is fixed to the voltage detection unit, A second member is disposed on the outside of the first member, with one end fixed to the busbar, An elastic member interposed between the first member and the second member, An expandable / contractable member interposed between the first member and the busbar, which expands and contracts so that the voltage detection unit and the busbar come into contact when the temperature is below a predetermined temperature, and expands and contracts so that the voltage detection unit and the busbar separate when the temperature is above the predetermined temperature, A busbar structure equipped with this feature.

2. The busbar structure according to claim 1, wherein the expansion and contraction member is made of a shape memory alloy.

3. The busbar structure according to claim 1, wherein the expansion and contraction member is fixed to the busbar using a thermally conductive adhesive.

4. The busbar structure according to claim 1, wherein the expansion and contraction member contains a liquid that vaporizes when the temperature is above the predetermined temperature, and at least a portion of it is made of a material that can expand by internal pressure.

5. The busbar structure according to claim 1, wherein the first member is formed to be slidable along the inner wall of the second member.

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