Bus bar 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 for connecting a plurality of batteries.

Background Art

[0002] In Patent Document 1, in order to detect abnormal heat generation of a bus bar at an early stage, the melting point of a fixing claw provided on a resin frame and fixing a voltage detection line terminal to the bus bar is made 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 detaches from the bus bar. A bus bar structure is disclosed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems 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 detaches 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 above a predetermined temperature is temporary, it is necessary to replace or repair the fixing claw.

[0005] The present disclosure has been made in view of the above circumstances, and an object thereof 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 Problems

[0006] The bus bar structure according to the present invention described in claim 1 includes a bus bar connecting a plurality of batteries, a voltage detection unit provided on the bus bar for detecting the voltage of the battery, a first member having one end fixed to the voltage detection unit, a second member disposed outside the first member and having one end fixed to the bus bar, an elastic member interposed between the first member and the second member, and an expansion and contraction member interposed between the first member and the bus bar, which expands and contracts so that the voltage detection unit and the bus bar come into contact with each other when the temperature is less than a predetermined temperature.

[0007] In the bus bar structure according to the present invention described in claim 1, the expansion and contraction member interposed between the first member and the bus bar expands and contracts so that the voltage detection unit and the bus bar come into contact with each other when the temperature is less than a predetermined temperature. In other words, the expansion and contraction member expands and contracts so that the voltage detection unit and the bus bar are separated from each other when the temperature is equal to or higher than a predetermined temperature. That is, when the expansion and contraction member expands when the temperature is equal to or higher than a predetermined temperature, the expansion and contraction member pushes up the first member against the biasing force of the elastic member, so that the voltage detection unit fixed to the first member is also pushed up and the voltage detection unit and the bus bar are separated from each other.

[0008] When the expansion and contraction member changes from a temperature equal to or higher than a predetermined temperature to a temperature less than a predetermined temperature, the expansion and contraction member contracts, and the first member is pushed down by the biasing force of the elastic member. Therefore, the voltage detection unit fixed to the first member is pushed down, and the voltage detection unit and the bus bar come into contact with each other. In this way, by contacting the voltage detection unit and the bus bar only when the temperature is less than a predetermined temperature, when the heat generation of the bus bar above the predetermined temperature subsides, the voltage can be measured again without replacing or repairing the parts.

[0009] The bus bar structure according to the present invention described in claim 2, in the configuration according to claim 1, the expansion and contraction member is formed of a shape memory alloy.

[0010] In the bus bar structure according to the present invention described in claim 2, since the expansion and contraction member is formed of a shape memory alloy, the thermal conductivity of the expansion and contraction member is good, and the heat generation of the bus bar can be detected in a short period of time.

[0011] The bus bar structure according to the present invention described in claim 3, in the configuration described in claim 1 or claim 2, the expansion and contraction member is fixed to the bus bar using an adhesive having thermal conductivity.

[0012] In the bus bar structure according to the present invention described in claim 3, since the expansion and contraction member is fixed to the bus bar using an adhesive having thermal conductivity, the heat generated by the bus bar can be transmitted to the expansion and contraction member more quickly through the adhesive. Further, when the expansion and contraction member is formed of a spring member, the contact area, that is, the heat transfer area, between the bus bar and the expansion and contraction member, which tends to be reduced by the adhesive, can be improved.

[0013] The bus bar structure according to the present invention described in claim 4, in the configuration described in claim 1, the expansion and contraction member is formed of a material in which a liquid that vaporizes when the temperature is equal to or higher than the predetermined temperature is contained therein, and at least a part thereof is expandable by internal pressure.

[0014] In the bus bar structure according to the present invention described in claim 4, the expansion and contraction member is formed of a material in which a liquid that vaporizes when the temperature is equal to or higher than the predetermined temperature is contained therein, and at least a part thereof is expandable by internal pressure. Therefore, when the temperature becomes equal to or higher than the predetermined temperature, the liquid vaporizes and the internal pressure rises, so that the portion formed of the expandable material can expand and push up the first member.

[0015] The bus bar structure according to the present invention described in claim 5, in the configuration described in any one of claims 1 to 4, the first member is formed to be slidable along the inner wall of the second member.

[0016] In the bus bar structure according to the present invention described in claim 5, since the first member is formed to be slidable along the inner wall of the second member, when the first member is pushed up, it can move along the inner wall of the second member, so that the horizontal state of the first member is more easily maintained. Therefore, since the voltage detection unit fixed to the first member can also be moved while maintaining the horizontal state, the detection accuracy by the voltage detection unit can be improved.

Advantages of the Invention

[0017] In the bus bar structure according to the present invention, when the heat generation of the bus bar subsides, the voltage can be measured again without replacing or repairing the parts.

Brief Description of the Drawings

[0018]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Embodiments for Carrying Out the Invention

[0019] (First Embodiment) Hereinafter, with reference to FIGS. 1 to 5, the bus bar structure 10 according to the first embodiment of the present invention will be described. In the description of the drawings, the same or equivalent elements are denoted by the same reference numerals, and redundant 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 on various vehicles such as forklifts, hybrid vehicles, and electric vehicles, for example.

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

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

[0023] The bus bar 12 is formed in a flat plate shape and electrically connects between cells 20 adjacent to each other in one direction. Specifically, it electrically connects the external terminals 24 of adjacent cells 20. In the present embodiment, as shown in FIG. 1, on the left side, one bus bar 12 electrically connects 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 (upper side) of the two bus bars 12 electrically connects two positive terminals, which are the external terminals 24 of two adjacent cells 20, and the other (lower side) bus bar 12 electrically connects two negative terminals, which are the external terminals 24 of the remaining two adjacent cells 20. Here, in FIG. 1, the white arrows indicate the flow of current.

[0024] The voltage detection unit 14 measures the voltage of each cell 20. The voltage detection unit 14 can use a known voltmeter. Each voltage detection unit 14 is connected to an ECU (Electronic Control Unit) via an electric wire 14A. In FIG. 1, only the voltage detection unit 14 is shown, but there are also members included in the bus bar structure 10 to be described later in the implementation. The bus bar structure 10 will be described in detail later.

[0025] The conductive member 30 is disposed so as to contact each cell 20. In the present embodiment, the conductive member 30 is arranged to contact the lower surface of each cell 20. The conductive member 30 has a cooling function for cooling the cell 20. In the present embodiment, as an example, it is assumed that the conductive member 30 is constituted by a cooler, but the present invention is not limited thereto, and the conductive member 30 may be constituted by a member different from the cooler.

[0026] Also, although not shown, a separator formed of an insulator such as resin may be disposed between adjacent cells 20.

[0027] Next, the bus bar structure 10 will be described. As shown in FIG. 2, the bus bar structure 10 includes a bus bar 12, a voltage detection unit 14, a first member 16, a second member 18, an elastic member 40, and an expansion and contraction member 42. The voltage detection unit 14 is provided on the bus bar 12.

[0028] The first member 16 is a resin structure, and includes, as an example, a main body portion 16A formed in a cylindrical shape, and a substantially circular flange portion 16B protruding outward from the outer peripheral surface of the substantially central portion in the vertical direction of the main body portion 16A. The lower end of the main body portion 16A is fixed to the upper surface of the voltage detection unit 14.

[0029] The second member 18 is disposed outside the first member 16, and includes, as an example, a cylindrical portion 18A formed in a cylindrical shape, and a disk portion 18B protruding substantially horizontally inward from the upper end of the cylindrical portion 18A and having an opening at 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 bus bar 12.

[0030] In the present embodiment, the first member 16 is configured to be slidable 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 slidable in the vertical direction along the inner wall of the cylindrical portion 18A of the second member 18. In FIGS. 2 and 3, although there is a gap between the side end surface of the flange portion 16B and the inner wall of the cylindrical portion 18A, they are actually in contact with each other to such an extent that they are slidable.

[0031] The elastic member 40 is configured by a spring member as an example, and is interposed between the first member 16 and the second member 18. Specifically, the elastic member 40 is configured by a substantially cylindrical spring member, is disposed inside the second member 18, and is disposed so as to surround the upper end side of the flange portion 16B of the first member 16. Further, the lower end of the elastic member 40 is in contact with the upper surface of the flange portion 16B of the first member 16, and the upper end is in contact with the lower surface of the disk portion 18B of the second member 18. The elastic member 40 biases the first member 16 downward, that is, toward the bus bar 12 side.

[0032] The expansion and contraction member 42 is formed of a shape memory alloy, and is formed as a substantially cylindrical spring member as an example. The expansion and contraction member 42 is interposed between the first member 16 and the bus bar 12. Specifically, the expansion and contraction member 42 is disposed below the flange portion 16B of the first member 16, and the lower end is fixed to the bus bar 12. In the present embodiment, as an example, the expansion and contraction member 42 is fixed to the upper surface of the bus bar 12 using an adhesive 44 having thermal conductivity.

[0033] When the expansion and contraction member 42 is below a preset predetermined temperature, since the spring force is weak, it is pressed by the biasing force of the elastic member 40, and the length in the vertical direction (axial direction) is contracted. Here, in the present embodiment, the preset predetermined temperature is the deformation temperature at which the shape memory alloy deforms.

[0034] On the other hand, when the temperature becomes equal to or higher than the predetermined temperature, since the spring force of the expansion and contraction member 42 becomes stronger than in the case where the temperature is lower than the predetermined temperature, the expansion and contraction member 42 returns to its original shape due to the reaction force of the expansion and contraction member 42 that opposes the biasing force of the elastic member 40. That is, the length of the expansion and contraction member 42 in the vertical direction (axial direction) extends (expands). Further, when the temperature of the expansion and contraction member 42 becomes lower than the predetermined temperature in the extended state, since the spring force weakens, the expansion and contraction member 42 is pressed by the biasing force of the elastic member 40, and the length in the vertical direction (axial direction) contracts.

[0035] As shown in FIG. 4(A), for example, when the temperature of the expansion and contraction member 42 rises over time, as shown in FIG. 4(B), the load indicating the reaction force of the expansion and contraction member 42 begins to rise from time C at which the temperature becomes the predetermined temperature B. Then, when the load indicating the reaction force of the expansion and contraction member 42 becomes larger than the load D which is the load indicating the biasing force of the elastic member 40 toward the bus bar 12 side (on the right side of the load indicated by the arrow E in FIG. 3), at time F when the load D < reaction force, the expansion and contraction member 42 begins to extend (expand) in the vertical direction (axial direction) as shown in FIG. 3, and begins to push up the flange portion 16B of the first member 16.

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

[0037] On the other hand, when the temperature of the expansion and contraction member 42 drops below a predetermined temperature from the state where the expansion and contraction member 42 shown in FIG. 3 is expanded, the load D, which is the load indicating the biasing force toward the bus bar 12 side of the elastic member 40, becomes larger than the load indicating the reaction force of the expansion and contraction member 42 (to the left of the load indicated by the arrow E in FIG. 3). Then, the expansion and contraction member 42 is pressed by the biasing force of the elastic member 40, and the length in the vertical direction (axial direction) starts to contract, and the first member 16 is also pushed downward together. Therefore, the voltage detection unit 14 fixed to the first member 16 also starts to move downward. As shown in FIG. 2, the expansion and contraction member 42 separates from the flange portion 16B of the first member 16, and the voltage detection unit 14 comes into contact with the bus bar 12. When the voltage detection unit 14 comes into contact with the bus bar 12, the voltage detected by the voltage detection unit 14 becomes a value larger than 0V.

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

[0039] In step S12, when the acquired voltage value is greater than the threshold value (step S12; YES), the ECU 32 returns to step S11 and proceeds to the processing after step S11. On the other hand, in step S12, when the acquired voltage value is less than or equal to the threshold value (step S12; NO), in step S13, the ECU 32 determines that an abnormality has occurred between the cells 20.

[0040] Normally, when an abnormality occurs in the cells 20 arranged in parallel, the resistance of the bus bar 12 connected to the cell 20 in which the abnormality has occurred becomes larger compared to the case where no abnormality has occurred. Therefore, due to the resistance difference, a larger current flows from the side with the larger resistance to the side with the smaller resistance, so that the temperature of the bus bar 12 becomes higher than expected. When the temperature of the bus bar 12 becomes high, heat is conducted to the expansion and contraction member 42 fixed to the upper surface of the bus bar 12 using the adhesive 44 having heat conductivity, and the temperature of the expansion and contraction member 42 also rises.

[0041] When the temperature of the expansion and contraction member 42 becomes equal to or higher than a predetermined temperature, the expansion and contraction member 42 returns to its original shape against the biasing force of the elastic member 40 as described above, and the length in the vertical direction expands, pushing up the flange portion 16B of the first member 16. As a result, since the first member 16 floats, the voltage detection unit 14 fixed to the first member 16 also floats, and the voltage output by the voltage detection unit 14 becomes 0V. Thus, according to the above structure, the high-temperature state generated by the abnormality in the cell 20 can be detected as a change in voltage.

[0042] Then, since the voltage value acquired by the ECU 32 becomes 0V (threshold value), the ECU 32 determines in step S13 that an abnormality has occurred in the bus bar 12, that is, between the cells 20. Therefore, in step S14, the ECU 32 intervenes in the protection control of the battery module 1 to execute the evacuation running mode. The evacuation running mode includes output limitation of the power output from the battery module. Then, the ECU 32 returns to step S11 and proceeds with the processing after step S11.

[0043] Next, the operation and effect of the bus bar structure 10 in the first embodiment will be described.

[0044] In the bus bar structure 10 according to the first embodiment, when the temperature is lower than a predetermined temperature, the expansion and contraction member 42 interposed between the first member 16 and the bus bar 12 expands and contracts so that the voltage detection unit 14 and the bus bar 12 come into contact with each other. In other words, when the temperature is equal to or higher than the predetermined temperature, the expansion and contraction member 42 expands and contracts so that the voltage detection unit 14 and the bus bar 12 are separated from each other. That is, when the expansion and contraction member 42 expands when the temperature is equal to or higher than the predetermined temperature, the expansion and contraction member 42 pushes up the first member 16 against the biasing force of the elastic member 40, so that the voltage detection unit 14 fixed to the first member 16 is also pushed up and the voltage detection unit 14 and the bus bar 12 are separated from each other.

[0045] When the expansion and contraction member 42 changes from a temperature equal to or higher than the predetermined temperature to a temperature lower than the predetermined temperature, the expansion and contraction member 42 contracts, and the first member 16 is pushed down by the biasing force of the elastic member 40. Therefore, the voltage detection unit 14 fixed to the first member 16 is pushed down, and the voltage detection unit 14 and the bus bar 12 come into contact with each other. In this way, by bringing the voltage detection unit 14 and the bus bar 12 into contact with each other only when the temperature is lower than the predetermined temperature, when the heat generation of the bus bar 12 at a temperature equal to or higher than the predetermined temperature subsides, the voltage can be measured again without replacing or repairing the components.

[0046] Further, in the bus bar structure 10 according to the first embodiment, since the expansion and contraction member 42 is formed of a shape memory alloy, the thermal conductivity of the expansion and contraction member 42 is good, and the heat generation of the bus bar can be detected in a short period of time.

[0047] Further, in the bus bar structure 10 according to the first embodiment, since the expansion and contraction member 42 is fixed to the bus bar 12 using the heat-conductive adhesive 44, the heat generation of the bus bar 12 can be transmitted to the expansion and contraction member 42 more quickly through the adhesive 44. Further, since the expansion and contraction member 42 is formed of a spring member, the contact area between the bus bar 12, which tends to become smaller due to the adhesive 44, and the expansion and contraction member 42, that is, the heat transfer area, can be improved.

[0048] Also, in the bus bar structure 10 according to the first embodiment, the first member 16 is formed to be slidable 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, so that the horizontal state of the first member 16 is more easily maintained. As a result, the voltage detection unit 14 fixed to the first member 16 can also be moved while maintaining the horizontal state, so that the detection accuracy by the voltage detection unit 14 can be improved.

[0049] Also, in the bus bar structure 10 according to the first embodiment, when detecting heat generation, the high-temperature state generated due to an abnormality in the cell 20 can be grasped as a change in voltage. Here, the conventional bus bar structure will be described. FIG. 11 is a flowchart showing a series of control processes for heat generation detection in the conventional bus bar structure. In the conventional bus bar structure, as shown in FIG. 11, first, in step S21, the ECU acquires the cell voltage value output by the voltage detection unit, and also acquires the current value in step S22. Further, in step S23, the ECU acquires the I-V characteristics by plotting the acquired voltage value and current value, and calculates the resistance value. In step S24, the ECU determines whether the calculated resistance value is equal to or less than a predetermined threshold value. If it is equal to or less than the threshold value (step S24; YES), the ECU returns to step S21 and proceeds to the processes after step S21.

[0050] On the other hand, in step S24, if the acquired resistance value is greater than the threshold value (step S24; NO), in step S25, the number of times the resistance value has become greater than the threshold value, that is, the number of resistance abnormalities, is counted up. In step S26, the ECU determines whether the count number is equal to or greater than a predetermined threshold value. If the count number is less than the threshold value (step S26; NO), the ECU returns to step S21 and proceeds to the processes after step S21.

[0051] On the other hand, in step S26, when the count number is equal to or greater than the threshold value (step S26; YES), the ECU intervenes in the protection control of the battery module to execute the evacuation driving mode. Then, the ECU returns to step S21 and proceeds with the processing after step S21.

[0052] As described above, in the conventional bus bar structure, the resistance value is calculated, and it takes about 30 seconds to calculate the resistance value once, so it takes time to calculate the resistance value once. In addition, in order to avoid misjudgment, for example, when the resistance value exceeds the threshold value a plurality of times, such as three times, it is determined that an abnormality has occurred between the cells, and it takes about 60 to 90 seconds to make an abnormality determination.

[0053] In contrast to such a conventional bus bar structure, in the bus bar structure 10 of the first embodiment, it is only necessary to determine the value of the voltage value output from the voltage detection unit 14 to determine whether an abnormality has occurred between the cells 20, so the time required for abnormality determination can be shortened compared with the prior art.

[0054] In addition, since it is not necessary to add a new sensor such as a device for detecting a current value, the cost can be suppressed. For example, a temperature sensor for detecting the temperature of the bus bar 12 may be provided, and the bus bar 12 and the voltage detection unit 14 may be brought into contact with or separated from each other according to the output from the temperature sensor. In this case, however, the cost of mounting the temperature sensor and the mounting means increases. In the present embodiment, since the already mounted voltage detection unit 14 can be utilized, the cost can be suppressed.

[0055] In the above embodiment, the expansion and contraction member 42 is a spring member formed of a shape memory alloy, but the present invention is not limited to this. Hereinafter, other embodiments of the expansion and contraction member will be described. Regarding the bus bar structure on which the expansion and contraction member is mounted, the same components as those in the first embodiment described above are denoted by the same reference numerals, and the description thereof will be omitted, and only the different portions will be described in detail.

[0056] (Second Embodiment) Hereinafter, with reference to FIG. 6, the expansion and contraction member 46 mounted on the bus bar structure 10A according to the second embodiment of the present invention will be described. As shown in FIG. 6, the expansion and contraction member 46 of the second embodiment includes a spring 46A formed of a shape memory alloy and a substantially disk-shaped flat plate member 46B formed of a 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 bus bar 12 using an adhesive 44 having thermal conductivity. Further, the spring 46A is fixed to the upper surface of the flat plate member 46B using an adhesive 44 having thermal conductivity.

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

[0058] (Third Embodiment) Hereinafter, with reference to FIGS. 7 to 10, the expansion and contraction member 50 mounted on the bus bar structure 10B according to the third embodiment of the present invention will be described. As shown in FIGS. 7 to 9, the expansion and contraction member 50 of the third embodiment includes a case portion 52 and a lid portion 54. The case portion 52 is formed of a cylindrical box body with an open upper portion and is formed of a material having rigidity such that it does not deform under the internal pressure described later.

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

[0060] Inside the case portion 52, a liquid 60 that vaporizes when the temperature is equal to or higher than a predetermined temperature is accommodated. Here, the predetermined temperature is set to the boiling point of the liquid 60. The liquid 60 is a type of liquid whose boiling point is set to a temperature corresponding to the temperature of the bus bar 12 when an abnormality is determined to have occurred in the cell 20.

[0061] When the lid portion 54 is attached to the upper portion of the case portion 52, the expansion and contraction member 50 causes the lid portion 54 to expand in the vertical direction as shown in FIG. 10 due to the internal pressure that rises when the liquid 60 vaporizes.

[0062] That is, when the temperature is less than a preset predetermined temperature, the internal pressure 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 contacts the bus bar 12.

[0063] On the other hand, when the temperature of the bus bar 12 rises and the temperature of the liquid 16 becomes equal to or higher than the predetermined temperature, the internal pressure rises as compared with the case where the temperature is less than the predetermined temperature. Therefore, the lid portion 54 deforms (expands) in the vertical direction (axial direction). As shown in FIG. 10, when the lid portion 54 expands, the first member 16 is pushed up against the biasing force of the elastic member 40. Therefore, the voltage detection unit 14 fixed to the first member 16 is also pushed up and the voltage detection unit 14 is separated from the bus bar 12.

[0064] On the other hand, when the temperature of the liquid 60 inside the expansion and contraction member 50 drops below the predetermined temperature from the state where the expansion and contraction member 50 shown in FIG. 10 is expanded, the internal pressure decreases as compared with the case where the temperature is equal to or higher than the predetermined temperature. Therefore, the deformation (expansion) of the lid portion 54 contracts and returns to its original state. That is, as shown in FIG. 7, when the lid portion 54 contracts, the first member 16 is pushed down by the biasing force of the elastic member 40. Therefore, the voltage detection unit 14 fixed to the first member 16 is also pushed down and the voltage detection unit 14 contacts the bus bar 12.

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

[0066] [Remarks] In the above-described embodiments, the main body portion 16A of the first member 16 and the cylindrical portion 18A of the second member 18 are formed in a cylindrical shape. However, the present invention is not limited to this, and they may be in a polygonal cylindrical shape or can be appropriately changed.

[0067] Also, in the above-described embodiments, the flange portion 16B of the first member 16 is formed in a disc shape. However, the present invention is not limited to this. As long as the expansion and contraction member can abut, for example, a structure in which a plurality of convex portions protruding outward are provided may be used, and the shape is not particularly limited.

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

[0069] Also, in the above-described first and second embodiments, the expansion and contraction members 42 and 46 are fixed to the bus bar 12 using an adhesive having thermal conductivity. However, the present invention is not limited to this. They may be fixed by known techniques other than adhesives.

[0070] Moreover, the configuration of the present invention is not limited to the above-described embodiments, and the configuration can be appropriately changed as long as the problems can be solved.

Explanation of Reference Numerals

[0071] 10, 10A, 10B bus bar structures, 12 bus bar, 14 voltage detection unit, 16 first member, 18 second member, 20 cell (battery), 40 elastic member, 42, 46, 50 expansion and contraction members, 44 adhesive, 60 liquid

Claims

1. A bus bar connecting between a plurality of batteries, a voltage detection unit provided on the bus bar for detecting the voltage of the battery, a first member having one end fixed to the voltage detection unit, a second member disposed outside the first member and having one end fixed to the bus bar, an elastic member interposed between the first member and the second member, an expansion and contraction member interposed between the first member and the bus bar, which expands and contracts so that the voltage detection unit and the bus bar come into contact with each other when the temperature is lower than a predetermined temperature, A bus bar structure comprising the same.

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

3. The bus bar structure according to claim 1, wherein the expansion and contraction member is fixed to the bus bar using an adhesive having thermal conductivity.

4. The bus bar structure according to claim 1, wherein the expansion and contraction member is formed of a material in which a liquid that vaporizes when the temperature is equal to or higher than the predetermined temperature is accommodated therein and at least a part thereof can be expanded by internal pressure.

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

Images