JP5428489B2 - Battery pack - Google Patents

Description

  The present invention generally relates to battery packs, and more specifically to a battery pack mounted on a vehicle as a power source for traveling.

  Regarding a conventional battery pack, for example, Japanese Patent Laying-Open No. 2008-53019 discloses a power storage module aimed at reducing the size or weight (Patent Document 1). A battery module as a power storage module disclosed in Patent Document 1 is a laminate in which a plurality of battery cells (lithium ion batteries) are laminated, an end plate disposed at both ends of the laminate, and the end plates are fastened together. A restraining band.

  Japanese Patent Laid-Open No. 9-120808 aims to suppress the deterioration of the performance by reducing the performance of the unit cell in use while stably strengthening the binding strength while being lightweight and having high productivity. A laminated sealed alkaline storage battery is disclosed (Patent Document 2).

JP 2008-53019 A JP-A-9-120808

  In the battery module disclosed in Patent Document 1 described above, a restraining band for restraining a plurality of battery cells integrally is fixed to the side wall of the end plate by rivets, bolts, or the like. However, when the restraint band comes off from the end plate for some reason, the pressure distribution on the battery restraint surface by the end plate changes and local load loss occurs. In this case, unintended deterioration such as lithium (Li) precipitation, internal short circuit, and gas generation occurs inside the battery, and the reliability of the battery module may be reduced.

  Therefore, an object of the present invention is to solve the above-described problem and to provide a battery pack having high reliability.

  The battery pack according to the present invention includes a plurality of stacked battery cells, a pair of end plates, a restraining band, and a band holding member. The pair of end plates are disposed at both ends of the plurality of battery cells. The restraining band causes a clamping force in the stacking direction to act on the battery cell by sandwiching the pair of end plates. The restraining band is fixed to the end plate. The band holding member is provided so as to hold the restraining band in a state where the pair of end plates are sandwiched.

  According to the battery pack configured as described above, even if the end plate and the restraint band are unfixed, the restraint band is held in a state of sandwiching the pair of end plates by the band holding member. Accordingly, it is possible to maintain a state in which the tightening force is applied to the battery cell and to prevent a change in the pressure distribution applied to the constraining surface of each battery cell. As a result, the reliability of the battery pack can be improved.

  Preferably, the restraint band is bent in one direction from both ends of the extending portion and the extending portion extending in the stacking direction of the battery cells in a state where the pair of end plates are sandwiched, and a tensile force acts on the extending portion. It has the 1st bending part and the 2nd bending part which are each latched by a pair of end plates. The band holding member is provided so as to surround the periphery of the extending portion.

  According to the battery pack configured as described above, the band holding member functions as a guide member that keeps the positional deviation of the restraining band within a predetermined range. Thereby, a 1st bending part and a 2nd bending part can be hold | maintained in the state latched by a pair of end plate, respectively.

  Preferably, the restraint band is bent in one direction from both ends of the extending portion and the extending portion extending in the stacking direction of the battery cells in a state where the pair of end plates are sandwiched, and a tensile force acts on the extending portion. It has the 1st bending part and the 2nd bending part which are each latched by a pair of end plates. The band holding member is provided so as to press the extending portion in the bending direction of the first bent portion and the second bent portion.

  According to the battery pack configured as described above, the band holding member functions as a stopper that prevents the displacement of the restraining band. Thereby, a 1st bending part and a 2nd bending part can be hold | maintained in the state latched by a pair of end plate, respectively.

  As described above, according to the present invention, a battery pack having high reliability can be provided.

1 is a perspective view schematically showing a battery pack in an embodiment of the present invention. It is a side view which shows the structure of the battery pack of the range enclosed with the dashed-two dotted line II in FIG. It is a side view which shows the structure of the battery pack of the range enclosed with the dashed-two dotted line III in FIG.

  Embodiments of the present invention will be described with reference to the drawings. In the drawings referred to below, the same or corresponding members are denoted by the same reference numerals.

  FIG. 1 is a perspective view schematically showing a battery pack according to an embodiment of the present invention.

  Referring to FIG. 1, a battery pack 10 is mounted on a hybrid vehicle that uses an internal combustion engine such as a gasoline engine or a diesel engine and a motor supplied with power from a chargeable / dischargeable battery (secondary battery) as a power source. ing. The battery pack 10 is installed at an appropriate location on the vehicle, for example, in the vehicle compartment (under the seat or in the console box) or the luggage room.

  The battery pack 10 has a plurality of battery cells 21. Each battery cell 21 consists of a lithium ion battery.

  The plurality of battery cells 21 are stacked in one direction indicated by an arrow 101 (hereinafter referred to as a stacking direction of the battery cells 21). The battery cell 21 has a substantially rectangular parallelepiped thin plate shape. The battery cell 21 has a restraining surface 21a. The constraining surface 21 a has the largest area among the plurality of side surfaces forming the appearance of the battery cell 21. The restraining surface 21a has a planar shape. The plurality of battery cells 21 are stacked such that the constraining surfaces 21a face each other between the battery cells 21 adjacent in the stacking direction.

  A battery module 20 is configured by the plurality of stacked battery cells 21. The external appearance of the battery module 20 has a substantially rectangular parallelepiped shape, and the direction in which the long side of the battery module 20 extends coincides with the stacking direction of the battery cells 21 when viewed in plan.

  The battery cell 21 has a positive terminal 23p and a negative terminal 23q. The plurality of battery cells 21 are stacked such that the positive electrode terminal 23p and the negative electrode terminal 23q are arranged between the battery cells 21 adjacent in the stacking direction. Between the battery cells 21 adjacent to each other, the positive terminal 23p and the negative terminal 23q are connected by a bus bar (not shown). With such a configuration, the plurality of battery cells 21 are electrically connected to each other in series.

  Each battery cell 21 is covered with a resin battery holder 26 in order to provide a gap for circulating cooling air between the battery cells 21 adjacent in the stacking direction.

  The battery pack 10 further includes an end plate 30m and an end plate 30n (hereinafter referred to as an end plate 30 unless otherwise distinguished). The end plate 30 is made of a resin material such as polypropylene or a polymer of polypropylene.

  The end plate 30m and the end plate 30n are respectively disposed at both ends of the plurality of stacked battery cells 21, in other words, at both ends of the battery module 20 in the stacking direction of the battery cells 21.

  The end plate 30 has a top surface 31 and side surfaces 32. The top surface 31 faces upward when the battery module 20 is viewed in plan. The side surface 32 faces the stacking direction of the battery cells 21. The side surface 32 is connected to the top surface 31 at a position bent at a right angle from the top surface 31.

  The battery pack 10 further includes an upper restraint band 41s and a lower restraint band 41t (hereinafter referred to as a restraint band 41 unless otherwise distinguished). The upper restraint band 41s and the lower restraint band 41t are provided on the opposing side surfaces (upper side surface and lower side surface) of the battery module 20, respectively. The restraint band 41 is formed from a metal, for example, a steel plate.

  The restraint band 41 sandwiches the end plate 30m and the end plate 30n so as to apply a tightening force in the stacking direction to the plurality of battery cells 21. Both ends of the restraint band 41 are locked to the end plate 30m and the end plate 30n, respectively. In this state, the plurality of battery cells 21 are restrained integrally in the stacking direction. Due to the restraint state of the battery cell 21 by the restraint band 41, a uniform surface pressure acts on the restraint surface 21 a of the battery cell 21. Both ends of the restraint band 41 are fixed to the end plate 30m and the end plate 30n, respectively.

  The more specific shape of the restraint band 41 will be described. The restraint band 41 includes an extended portion 42, a bent portion 43m as a first bent portion, and a bent portion 43n as a second bent portion (hereinafter, unless otherwise specified). And a bent portion 43).

  The extending part 42 extends in the stacking direction of the battery cells 21. The extending portion 42 is formed by extending linearly on the side surface of the battery module 20.

  The bent portion 43 is bent at a right angle from the extending portion 42 and is disposed on the side surface 32 of the end plate 30. The bent portion 43m is locked to the side surface 32 of the end plate 30m, and the bent portion 43n is locked to the side surface 32 of the end plate 30n. In this state, a tensile force along the stacking direction of the battery cells 21 acts on the extending portion 42. In the present embodiment, the bent portion 43 is fixed to the end plate 30 using a rivet 46 as a fixing member.

  A bolt may be used instead of the rivet 46 for fixing the restraining band 41 to the end plate 30.

  FIG. 2 is a side view showing the structure of the battery pack in a range surrounded by a two-dot chain line II in FIG. Referring to FIG. 2, battery pack 10 in the present embodiment further includes guide member 51 for holding upper restraint band 41s in a state where end plate 30m and end plate 30n are sandwiched.

  The guide member 51 is provided on the top surface 31 so as to surround the periphery of the extending portion 42. The guide member 51 is fixed to the end plate 30. The guide member 51 is provided so as to restrict the movement of the upper restraint band 41 s that sandwiches the end plate 30 in the direction of removal (directions indicated by arrows 106 and 107 in FIG. 2). In order to secure a catching margin between the guide member 51 and the upper restraint band 41s in the direction indicated by the arrow 106, the guide member is more than the length A of the gap between the guide member 51 and the upper restraint band 41s (the extending portion 42). The catch length B between 51 and the upper restraint band 41s is set to be larger (A <B).

  FIG. 3 is a side view showing the structure of the battery pack in a range surrounded by a two-dot chain line III in FIG. Referring to FIG. 3, battery pack 10 according to the present embodiment further includes a stopper member 52 for holding lower restraint band 41t in a state where end plate 30m and end plate 30n are sandwiched.

  The stopper member 52 is provided so as to press the extending portion 42 of the lower restraining band 41t toward the bending direction of the bent portion 43 (the direction indicated by the arrow 108 in FIG. 3), that is, toward the end plate 30. In other words, the stopper member 52 is provided such that the extending portion 42 is sandwiched between the stopper member 52 and the end plate 30.

  With reference to FIGS. 2 and 3, it is assumed that the rivet 46 for fixing the restraining band 41 to the end plate 30 is damaged or falls off the end plate 30. Even in such a case, in the battery pack 10 according to the present embodiment, since the positional displacement of the upper restraint band 41s is limited by the guide member 51, the upper restraint band 41s is connected to the end plate 30m and the end plate 30n. Can be held in a sandwiched state. Further, since the stopper member 52 can prevent the lower restraint band 41t from being displaced, the lower restraint band 41t can be held in a state where the end plate 30m and the end plate 30n are sandwiched.

  The structure of the battery pack according to the embodiment of the present invention described above will be described together. The battery pack 10 includes a plurality of stacked battery cells 21, a pair of end plates 30 (30m, 30n), a restraint. It has a band 41 (upper restraint band 41s, lower restraint band 41t), a guide member 51 as a band holding member, and a stopper member 52. The pair of end plates 30 (30m, 30n) are disposed at both ends of the plurality of battery cells 21. The restraint band 41 (upper restraint band 41 s and lower restraint band 41 t) holds the pair of end plates 30 (30 m and 30 n) to exert a tightening force in the stacking direction on the battery cells 21. The restraint band 41 (upper restraint band 41s, lower restraint band 41t) is fixed to the end plate 30 (30m, 30n). The guide member 51 and the stopper member 52 are provided so as to hold the restraint band 41 (the upper restraint band 41s and the lower restraint band 41t) in a state where the pair of end plates 30 (30m, 30n) are sandwiched.

  According to the battery pack 10 according to the embodiment of the present invention configured as described above, even if the rivet 46 is broken or falls off the end plate 30, the battery module by the restraining band 41 is used. Twenty tightening states can be maintained. Thereby, the change of the pressure distribution made to act on the restraining surface 21a of the battery cell 21 can be suppressed, and the deterioration of the battery pack 10 can be prevented.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The present invention is mainly used for a vehicle provided with a motor powered by a battery as a power source.

  10 battery pack, 21 battery cell, 30, 30m, 30n end plate, 41 restraint band, 41s upper restraint band, 41t lower restraint band, 42 extending part, 43, 43m, 43n bent part, 51 guide member, 52 stopper member .

Claims (2)

A battery module composed of a plurality of stacked battery cells, in which cooling air is circulated in a horizontal direction between the adjacent battery cells;
A pair of end plates disposed at both ends of the plurality of battery cells;
A clamping band fixed to the end plate by clamping a pair of the end plates to cause a clamping force in the stacking direction to act on the battery cell;
A band holding member that holds the restraining band in a state of sandwiching the pair of end plates;
The battery module has a substantially rectangular parallelepiped shape having an upper side surface from which a positive electrode terminal and a negative electrode terminal extend, and a lower side surface disposed on the opposite side of the upper side surface,
As the restraint band, an upper restraint band provided on the upper side surface and a lower restraint band provided on the lower side surface are provided,
The upper restraint band extends in the stacking direction of the battery cells in a state where the pair of end plates are sandwiched, and is bent in one direction from both ends of the extending portion and the extending portion passing over the top surface of the end plate. A first bent portion and a second bent portion that are respectively locked to the pair of end plates so that a tensile force acts on the extending portion,
The band holding member is fixed to the top surface of the end plate by providing a gap around the extending portion,
Rather than the length of the gap between the band holding member in the vertical direction and the top surface of the extending portion facing the band holding member, the top surface of the extending portion and the top surface of the end plate in the vertical direction A battery pack with a larger distance between them . The lower restraining band is bent in one direction from both ends of the extending portion and the extending portion extending in the stacking direction of the battery cells in a state where the pair of end plates are sandwiched, and a tensile force acts on the extending portion. A first bent portion and a second bent portion that are respectively locked to the pair of end plates,
2. The battery pack according to claim 1, wherein the band holding member is provided so as to press the extending portion in a bending direction of the first bent portion and the second bent portion.

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