JP2017174655A - Battery pack and method of manufacturing battery pack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery pack capable of successfully ensuring heat dissipation of a battery module in normal use and capable of preventing a housing from being broken in the occurrence of abnormality, and a method of manufacturing such a battery pack.SOLUTION: In a battery pack 1, a battery module 3 is accommodated in a housing 2. The housing 2 includes a fixed wall part 7 to which one surface side of the battery module 3 is fixed and a functional wall part 12 including a deformable part 13 which is in contact with the other surface side of the battery module 3 and deforms in a direction away from the other surface side of the battery module 3 when the inner pressure of the housing 2 rises.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a battery pack and a method for manufacturing the battery pack.

  In a battery cell such as a lithium ion secondary battery, charging and discharging are repeated during normal use. In particular, when charging is performed, the battery cell generates heat. Since the battery cell deteriorates when the high temperature state continues, the heat dissipation of the battery cell is important for realizing the long life of the battery cell. In the battery pack, the heat generated in the battery cell is released to the outside through a casing to which the battery cell (or a battery module that is an assembly of battery cells) is fixed.

  For example, in the assembled battery described in Patent Document 1, battery cases are stacked in a plurality of stages in a housing, and a battery module is accommodated in each battery case. In this assembled battery, a ventilation fan is provided on the upper surface of the uppermost battery case or the lower surface of the lowermost battery case so as to promote ventilation around the battery module. Further, for example, the assembled battery module described in Patent Document 2 contacts the surfaces of the plurality of secondary batteries in a predetermined high temperature region and dissipates heat from the surfaces of the plurality of secondary batteries in a predetermined low temperature region. A member is provided. In this assembled battery, the temperature of the secondary battery is adjusted to an appropriate operating temperature by the contact / separation of the heat dissipating member.

Japanese Patent Laid-Open No. 1-134851 JP2015-125930A

  By the way, in a battery pack, when abnormality arises in a battery cell, gas may be generated from the battery module side. Under such abnormal circumstances as the generation of gas, the temperature inside the housing, or the decompressed atmosphere outside the housing, the internal pressure of the housing will rise, so if the internal pressure becomes excessive, the housing will be damaged. It is possible to end up. In order to deal with such a problem, for example, in the method such as the assembled battery of Patent Document 2 described above, the heat dissipation member is deformed to the inside of the housing so as to contact the secondary battery at a high temperature (FIG. 1 of Patent Document 2). In addition, there is a possibility that the internal pressure of the housing may further increase under the situation where an abnormality has occurred. Therefore, there is a demand for a technique that can ensure good heat dissipation of the battery module during normal use and can suppress an increase in internal pressure of the casing when an abnormality occurs.

  The present invention has been made in order to solve the above-described problems. The battery pack can ensure good heat dissipation of the battery module during normal use and can prevent the casing from being damaged when an abnormality occurs, and such a battery pack. An object of the present invention is to provide a method for manufacturing a battery pack.

  A battery pack according to one aspect of the present invention is a battery pack in which a battery module is accommodated in a housing, and the housing includes a fixed wall portion to which one surface side of the battery module is fixed, and the other surface side of the battery module. And a functional wall portion having a deformation portion that is deformed in a direction away from the other surface side of the battery module when the internal pressure of the housing increases.

  In this battery pack, a housing that accommodates the battery module is provided with a fixed wall portion on which one surface side of the battery module is fixed, and a functional wall portion that contacts the other surface side of the battery module. During normal use, heat generated in the battery module is released to the outside of the housing through both the fixed wall portion and the functional wall portion, so that the heat dissipation of the battery module can be ensured satisfactorily. The functional wall portion is provided with a deforming portion that deforms in a direction away from the other surface side of the battery module when the internal pressure of the housing increases. Since the deforming portion is separated from the other surface side of the battery module, the volume in the housing is increased, and the internal pressure of the housing is suppressed from becoming excessive. Therefore, damage to the housing can be prevented when an abnormality occurs.

  Moreover, the heat transfer member may be provided in the contact surface which contacts the other surface side of a battery module in a deformation | transformation part. By configuring the contact surface using the heat transfer member, the heat generated in the battery module during normal use can be more efficiently transferred to the functional wall. Therefore, the heat dissipation of the battery module is further improved.

  Moreover, the deformation | transformation part may be contacting the at least center part of the other surface side of a battery module. The central portion of the battery module is a portion where heat generation is likely to occur compared to the end portion. Therefore, the heat dissipation of the battery module is further improved by bringing the contact surface into contact with at least the central portion on the other surface side of the battery module.

  The deformable portion is configured by a first wall portion that contacts the other surface side of the battery module, and a second wall portion that connects the first wall portion and the main body portion of the functional wall portion, and the thickness of the second wall portion. May be smaller than the thickness of the first wall. In this case, the deformable portion can be realized with a simple configuration. Moreover, when the internal pressure of a housing | casing rises because the thickness of a 2nd wall part is smaller than the thickness of a 1st wall part, a contact surface can be spaced apart more reliably from the other surface side of a battery module. .

  Moreover, the deformation | transformation part may be comprised with the bimetal. In this case, the deformable portion can be realized with a simple configuration.

  In addition, a plurality of battery modules are accommodated in the housing, and a plurality of deforming portions are provided in the functional wall portion corresponding to the arrangement positions of the battery modules, and the internal pressure of the housing is between the deforming portions. A non-deformable portion that does not deform even when it rises may be provided. In this case, the non-deformed portion becomes a rib of the functional wall portion, and the shape retaining property of the functional wall portion can be obtained both during normal use and when an abnormality occurs.

  A battery pack manufacturing method according to one aspect of the present invention is a battery pack manufacturing method in which a battery module is housed in a housing, and one surface of the battery module is fixed to a fixed wall portion of the housing. The functional wall portion of the housing is arranged with respect to the fixed wall portion so that the deforming portion that deforms when the internal pressure of the housing rises is opposed to the other surface side of the battery module at a constant interval. Pressing toward the module, the deformed portion is brought into contact with the other side of the battery module.

  In this battery pack manufacturing method, the functional wall portion is arranged with respect to the fixed wall portion so that the deformable portion faces the other surface side of the battery module at a constant interval, and then the deformable portion is pressed to Contact the other side. Thereby, the battery pack mentioned above can be obtained by a simple process. In addition, by measuring the pressure when the deforming portion is pressed, it is possible to grasp in advance the pressure when the deforming portion is separated from the other surface side of the battery module when the internal pressure of the housing increases.

  According to the present invention, the heat dissipation of the battery module can be secured satisfactorily during normal use, and the casing can be prevented from being damaged when an abnormality occurs.

It is a perspective view which shows one Embodiment of a battery pack. It is a longitudinal cross-sectional view of the battery pack at the time of normal use. It is a cross-sectional view of the battery pack during normal use. It is a longitudinal cross-sectional view of the battery pack at the time of abnormality occurrence. It is a cross-sectional view of the battery pack when an abnormality occurs. It is the schematic which shows one Embodiment of the manufacturing method of a battery pack. FIG. 7 is a schematic diagram illustrating a subsequent process of FIG. 6. It is the schematic which shows the modification of a functional wall part.

  Hereinafter, preferred embodiments of a battery pack and a battery pack manufacturing method according to one aspect of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a perspective view showing an embodiment of a battery pack. 2 is a longitudinal sectional view of the battery pack shown in FIG. 1, and FIG. 3 is a transverse sectional view thereof. The battery pack 1 shown in FIGS. 1 to 3 is configured as a battery of an industrial vehicle such as a forklift.

  The battery pack 1 is configured by housing a plurality of battery modules 3 in a housing 2. The battery module 3 includes, for example, an array in which a plurality of battery cells are arrayed, and a restraining member that applies a restraining load to the array in the battery cell array direction. The battery cell is a nonaqueous electrolyte secondary battery such as a lithium ion secondary battery.

  The housing 2 has a substantially rectangular parallelepiped box shape, for example. The material forming the housing 2 is a metal material such as iron, for example. When the battery pack 1 is mounted on a forklift, a function as a counterweight of the forklift may be added by providing a weight member on the outer surface of the housing 2.

  The housing 2 includes a base portion 4 and a lid portion 5 that covers the base portion 4. The base portion 4 has a rectangular plate-like bottom wall 6 that forms the bottom of the housing 2 and a rectangular plate-like fixed wall portion 7 to which the battery module 3 is fixed. The bottom wall 6 and the fixed wall portion 7 are formed thicker than the wall portion constituting the lid portion 5. The fixed wall portion 7 is erected substantially perpendicularly to the bottom wall 6 at the center portion in the width direction of the bottom wall 6.

  In the present embodiment, as shown in FIGS. 2 and 3, the four battery modules 3 are fixed in two rows and two rows on the one surface 7 a side of the fixed wall portion 7, and the four battery modules 3 are fixed on the other surface 7 b of the fixed wall portion 7. Battery modules 3 are fixed in two rows and two rows. A pair of brackets 8 and 8 are used to fix the battery module 3 to the fixed wall portion 7 (see FIG. 3). In each battery module 3, the brackets 8 and 8 are respectively fixed to the arrangement end of the battery cell array. The bracket 8, 8 is bolted to the fixed wall portion 7, whereby the one surface 3 a side of the battery module 3 is fixed to the fixed wall portion 7.

  The lid 5 includes a rectangular plate-shaped top wall 9 that forms the top of the housing 2, a pair of rectangular plate-shaped side walls 10 that form side portions in the longitudinal direction of the housing 2, and the width direction side of the housing 2. And a pair of rectangular plate-like side walls 11. The side walls 10 and 11 are erected on the edge of the top wall 9. By joining the tips of the side walls 10 and 11 to the edge of the bottom wall 6, the base portion 4 and the lid portion 5 are fixed so that the bottom wall 6 and the top wall 9 face each other. An internal space is formed. The joining of the side walls 10 and 11 and the bottom wall 6 may be by bolt fastening via a seal member or the like, or may be by welding.

  The side wall 11 of the lid part 5 is a part corresponding to the functional wall part in the present invention. A plurality of deforming portions 13 are provided on the side wall 11 (functional wall portion 12) corresponding to the arrangement position of the battery module 3. As shown in FIGS. 2 and 3, the deformable portion 13 includes a first wall portion 14 that has the same shape as the other surface 3 b of the battery module 3 or a slightly smaller rectangular shape, and a main body portion of the first wall portion 14 and the side wall 11. And the second wall portion 15 connecting the two. The thickness of the first wall portion 14 is, for example, equal to the thickness of the main body portion of the side wall 11. Here, the main body portion of the side wall 11 refers to a portion of the side wall 11 other than the first wall portion 14 and the second wall portion 15.

  The inner wall surface of the first wall portion 14 is located on the inner side of the main body portion of the side wall 11, and serves as a contact surface 14 a that contacts the other surface 3 b side of the battery module 3. The contact surface 14 a is in contact with substantially the entire surface including the central portion of the other surface 3 b of the battery module 3. A sheet-like heat transfer member 16 is provided on the contact surface 14a. The heat transfer member 16 may be an elastic member or a metal material such as copper. The elastic member may be formed by applying and curing a liquid TIM (Thermal Interface Material), or may be a solid TIM.

  The second wall portion 15 is provided obliquely with respect to the first wall portion 14 around the first wall portion 14, and connects the four sides of the first wall portion 14 to the main body portion of the side wall 11. . Therefore, when the side wall 11 is viewed from the outer surface side, the deformed portion 13 has a shape recessed in a rectangular shape with respect to the main body portion of the side wall 11. The inclination angle of the second wall portion 15 with respect to the first wall portion 14 is, for example, an obtuse angle. In addition, the thickness of the second wall portion 15 is smaller than the thickness of the first wall portion 14. For this reason, the second wall portion 15 can be deformed without deforming the first wall portion 14 when a constant force is applied in the thickness direction of the side wall 11.

  The thickness of the second wall portion 15 is preferably 0.2 to 0.7 times the thickness of the first wall portion, and more preferably 0.3 to 0.5 times. The width of the second wall portion 15 (the width in the direction connecting the first wall portion 14 and the body portion of the side wall 11) is the length of the short side of the first wall portion 14 (the first wall portion 14 is square). In some cases, the length is preferably 0.3 to 0.05 times the length of any one side. In this case, the second wall portion 15 can be easily deformed when a certain force is applied in the thickness direction of the side wall 11. It is preferable that the thickness of the second wall portion 15 is set to such an extent that it does not break even when the internal pressure of the housing 2 increases when an abnormality occurs.

  Due to the deformation of the second wall portion 15, the position of the first wall portion 14 is in contact with the other surface 3 b side of the battery module 3 inside the main body portion of the side wall 11 (see FIGS. 2 and 3), It is displaced between a separation position (see FIG. 4 and FIG. 5) that is separated from the other surface 3 b side of the battery module 3 outside the main body portion of the side wall 11. In the present embodiment, the second wall portions 15, 15 between the adjacent deformable portions 13, 13 are not continuous, and the body portion of the side wall 11 is not deformed portion 17 between the deformable portions 13, 13. As a certain width.

  In the battery pack 1 as described above, during normal use, as shown in FIGS. 2 and 3, the one surface 3 a side of the battery module 3 is fixed to the fixed wall portion 7, and the other surface 3 b side of the battery module 3 is the deformed portion 13. Touching. For this reason, the heat generated by the charging and discharging of the battery cells is released to the outside of the housing 2 through both the fixed wall portion 7 and the functional wall portion 12. Therefore, the heat dissipation of the battery module 3 can be ensured satisfactorily.

  On the other hand, in the battery pack 1, the internal pressure of the housing 2 rises when an abnormality occurs such as generation of gas when an abnormality occurs in the battery cell, temperature rise in the housing 2, or a reduced pressure atmosphere outside the housing 2. When the abnormality occurs, the internal pressure of the housing 2 increases to, for example, about 2 kPa. When the internal pressure of the housing 2 rises, the second wall portion 15 of the deformable portion 13 is deformed, and the first wall portion 14 is displaced from the contact position to the separated position as shown in FIGS. As the first wall portion 14 is displaced, the volume in the housing 2 increases. Therefore, excessive internal pressure of the housing 2 is suppressed, and damage to the housing 2 can be prevented when an abnormality occurs.

  Even when the first wall portion 14 is displaced from the contact position to the separated position, the fixed state between the one surface 3a side of the battery pack M and the fixed wall portion 7 is not released. Therefore, heat dissipation of the battery module 3 through the fixed wall portion 7 is continued at a certain level even when an abnormality occurs.

  In the battery pack 1, the heat transfer member 16 is provided on the contact surface 14 a that contacts the other surface 3 b side of the battery module 3 in the deformable portion 13. By configuring the contact surface 14a using the heat transfer member 16, the heat generated in the battery module 3 during normal use can be more efficiently transferred to the functional wall portion 12. Therefore, the heat dissipation of the battery module 3 is further improved.

  Further, in the battery pack 1, the contact surface 14 a of the deformable portion 13 is in contact with at least the center portion on the other surface 3 b side of the battery module 3. The central portion of the battery module 3 is a portion where heat generation is likely to occur compared to the end portion in the arrangement direction of the battery cells. Therefore, since the contact surface 14a is in contact with at least the central portion on the other surface 3b side of the battery module 3, the heat dissipation of the battery module 3 during normal use is further improved.

  In the battery pack 1, the deformed portion 13 is formed by the first wall portion 14 that contacts the other surface 3 b of the battery module 3 and the second wall portion 15 that connects the first wall portion 14 and the main body portion of the functional wall portion 12. Is configured. Further, the thickness of the second wall portion 15 is smaller than the thickness of the first wall portion 14. Thereby, the deformation | transformation part 13 is realizable with a simple structure. Since the thickness of the second wall portion 15 is smaller than the thickness of the first wall portion 14, the ease of displacement of the first wall portion 14 can be ensured. For this reason, when the internal pressure of the housing | casing 2 rises, the contact surface 14a can be spaced apart from the other surface 3b side of the battery module 3 more reliably.

  Further, in the battery pack 1, a non-deformable portion 17 that is not deformed even when the internal pressure of the housing increases is provided between the deformable portions 13 and 13. Since the non-deformable portion 17 serves as a rib of the functional wall portion 12, the strength of the functional wall portion 12 can be ensured even when a plurality of deformable portions 13 are provided. Therefore, the shape retaining property of the functional wall portion 12 can be obtained both during normal use and when an abnormality occurs.

  Then, the manufacturing method of the battery pack 1 mentioned above is demonstrated.

  When manufacturing the battery pack 1, first, as shown in FIG. 6, the base portion 4 of the housing 2 is prepared. And the battery module 3 is fixed to the predetermined position of the one surface 7a and the other surface 7b of the fixed wall part 7 in the base part 4 via the brackets 8 and 8.

  Next, as shown in FIG. 7, the lid 5 of the housing 2 is prepared. A plurality of deformed portions 13 are provided in advance on the side wall 11 of the lid portion 5 by pressing or the like. At this time, the first wall portion 14 of each deformable portion 13 is located outside the main body portion of the side wall 11 and in a separated position that is separated from the other surface 3b side of the battery module 3. After the tips of the side walls 10 and 11 of the lid part 5 are joined to the edge of the bottom wall 6 of the base part 4 to form the casing 2, the first wall part 14 at the separated position is directed to the inside of the casing 2. And press.

  Thereby, the 2nd wall part 15 deform | transforms and the 1st wall part 14 is displaced to the contact position which contacts the other surface 3b side of the battery module 3 inside the main-body part of the side wall 11. FIG. For example, an autograph can be used to press the first wall portion 14. In this step, it is preferable to measure the pressure at the time of pressing using a load cell incorporated in the autograph.

  According to such a method, the above-described battery pack 1 can be obtained by a simple process. Further, by measuring the pressure when the deforming portion 13 is pressed, the pressure when the deforming portion 13 moves away from the other surface 3b side of the battery module 3 when the internal pressure of the housing 2 increases, that is, the first wall. It becomes possible to grasp in advance the threshold value at which the portion 14 is displaced from the contact position to the separated position. By setting the threshold in consideration of the strength of the lid 5 and the specifications of the battery cells constituting the battery module 3, the increase in the internal pressure of the housing 2 can be more reliably mitigated, and the housing 2 is damaged when an abnormality occurs. Can be suppressed.

  The present invention is not limited to the above embodiment. For example, in the above embodiment, the fixed wall portion 7 and the functional wall portion 12 face each other in the housing 2, but the functional wall portion 12 may be provided on a wall portion that intersects the fixed wall portion 7. . Moreover, in the said embodiment, the deformation | transformation part 13 is by the 1st wall part 14 which contacts the other surface 3b of the battery module 3, and the 2nd wall part 15 which connects the 1st wall part 14 and the main-body part of the functional wall part 12. FIG. The deformation of the deformable portion 13 is realized by making the thickness of the second wall portion 15 smaller than the thickness of the first wall portion 14, but as shown in FIG. 18 may be comprised.

  The bimetal 18 is a member formed by bonding a plurality of metal plates having different coefficients of thermal expansion, and the shape changes according to a change in temperature. For example, an alloy of Fe and Ni is used for the metal plate on the low expansion side, and a Cu alloy is used for the metal plate on the high expansion side. The bimetal 18 is disposed so that the metal plate on the high expansion side faces the other surface 3b side of the battery module 3. Thereby, due to heat generation during normal use of the battery cell, the shape of the bimetal 18 changes to a concave shape in a direction in which the battery cell 3 is in close contact with the other surface 3b (a direction in which the volume in the housing 2 decreases). That is, during normal use of the battery cell, the bimetal 18 formed in a concave shape is kept in close contact with the other surface 3b of the battery module 3.

  On the other hand, when an abnormality occurs in the battery cell, it is caused by an increase in the internal pressure of the housing 2 due to the generation of gas, rather than a change in shape of the bimetal 18 due to rapid heat generation (a change in shape caused by a difference in thermal expansion). A change in shape of the bimetal 18 (a change in shape from a concave shape to a convex shape) is more noticeable. Therefore, the bimetal 18 having a concave shape during normal use changes into a convex shape due to an increase in the internal pressure of the housing 2 when an abnormality occurs, so that the same function as that of the deformed portion 13 described above can be achieved with a simple configuration. It becomes.

  DESCRIPTION OF SYMBOLS 1 ... Battery pack, 2 ... Case, 3 ... Battery module, 3a ... One side, 3b ... Other side, 7 ... Fixed wall part, 11 ... Side wall, 12 ... Functional wall part, 13 ... Deformation part, 14 ... 1st wall Part, 14a ... contact surface, 15 ... second wall part, 16 ... heat transfer member, 17 ... non-deformation part, 18 ... bimetal.

Claims (7)

A battery pack that houses a battery module in a housing,
The housing is
A fixed wall portion to which one side of the battery module is fixed;
A battery having a functional wall having a deforming portion that contacts the other surface of the battery module and deforms in a direction away from the other surface of the battery module when an internal pressure of the housing increases. pack.   The battery pack according to claim 1, wherein a heat transfer member is provided on a contact surface in contact with the other surface side of the battery module in the deformation portion.   The battery pack according to claim 1, wherein the deformable portion is in contact with at least a central portion on the other surface side of the battery module. The deformation portion is configured by a first wall portion that contacts the other surface side of the battery module, and a second wall portion that connects the first wall portion and a main body portion of the functional wall portion,
The battery pack according to claim 1, wherein a thickness of the second wall portion is smaller than a thickness of the first wall portion.   The battery pack according to claim 1, wherein the deformable portion is made of a bimetal. A plurality of the battery modules are accommodated in the housing,
The functional wall portion is provided with a plurality of deformation portions corresponding to the arrangement positions of the battery modules, and a non-deformation portion that does not deform even when the internal pressure of the housing rises between the deformation portions. The battery pack according to claim 1, wherein the battery pack is provided. A battery pack manufacturing method comprising a battery module housed in a housing,
Fixing one side of the battery module to the fixed wall of the housing;
The functional wall portion of the housing is arranged with respect to the fixed wall portion so that the deforming portion that deforms when the internal pressure of the housing rises is opposed to the other surface side of the battery module at a constant interval.
A method for manufacturing a battery pack, wherein the deforming portion is pressed toward the battery module, and the deforming portion is brought into contact with the other surface side of the battery module.

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