JP5450115B2 - Battery pack - Google Patents

Description

  The present invention relates to a battery pack, and more particularly to a structure of a holder for holding a unit cell.

Battery packs are widely used for electric tools, electric assist bicycles, electric motorcycles, hybrid vehicles (HEV), electric vehicles (PEV), and the like (see, for example, Patent Document 1).
In the battery pack according to the prior art, one or a plurality of unit cells having a cylindrical outer shape, a holder for storing the unit cells, and a substrate provided with a circuit or an external connection terminal are accommodated in an outer case. It has a configuration. Here, in the battery pack according to the related art, the unit cell is accommodated in the outer case while being held by the holder. This is provided in order to prevent the unit cell from moving in the outer case when vibration or impact is applied to the battery pack during use.

JP 2006-196277 A

  The battery pack of Patent Document 1 has a structure in which both ends of the unit cell are held by two holders. Although the unit cell can be held by such a structure, it is desired to disperse a contact area between the holder and the unit cell over a wide range when holding the unit cell. If the contact points between the holder and the unit cell are dispersed over a wide range, the unit cell can be held more reliably. As a result, the unit cell can be held by one holder. It should be noted that the contact area between the holder and the unit cell being dispersed over a wide range does not necessarily require a large contact area.

However, there is a problem that even if the holder is simply lengthened, the contact points cannot always be dispersed over a wide range.
Generally, the holder is integrally formed by a molding method such as injection molding, in which a resin is filled between a plurality of molds, and the wall surface of the insertion hole into which the unit cell is inserted is inclined so that the insertion port side extends. This is because a draft angle is attached to the wall surface of the insertion hole in order to facilitate removal from the mold during molding.

  Since the draft angle is given to the wall surface of the insertion hole as described above, when the holder (insertion hole) is lengthened, the unit cell can be held at the small diameter side end of the insertion hole. The inner diameter of the insertion hole gradually increases as the distance from the portion increases, making it difficult to hold the unit cell. For example, when trying to hold not only one end of a unit cell but also an intermediate part with one holder, or when trying to hold one end and the other end of a unit cell with one holder, The hole on the insertion port side of the holder expands due to the inclination, and the unit cell cannot be held on the insertion port side of the holder (or the middle part of the holder).

  The present invention has been made to solve the above-described problems, and is a holder that can hold a unit cell in a state where contact points with the unit cell are dispersed over a wide range, for example, one end of a unit cell and a cylinder from the holder. It aims at providing the battery pack provided with the holder which can hold | maintain a unit cell in the part spaced apart to the axial direction.

In order to achieve the above object, the present invention has the following features.
The battery pack according to the present invention is a battery pack in which one or a plurality of cylindrical unit cells are accommodated in a holder, and the holder accepts insertion in the cylinder axis direction for each of the unit cells. One or a plurality of receiving tubes are provided, and each receiving tube includes a peripheral wall that surrounds the inserted peripheral surface of the unit cell, and a plurality of ribs that are arranged on the wall surface in a circumferentially distributed state. And the peripheral wall is provided with a draft angle whose diameter is increased from the bottom end to the opening end on the wall surface, while each rib is a top gradient along the direction in which the unit cell is inserted. Is smaller than the draft of the peripheral wall, and the inserted unit cell is held by contacting the tops of the plurality of ribs.

  In the battery pack according to the present invention, the top slope of the plurality of ribs extending on the wall surface is made smaller than the draft of the peripheral wall. For this reason, for example, not only the bottom side end but also the middle part or the opening side end is in contact with the peripheral surface of the unit cell so that the unit cell moves laterally (in a direction perpendicular to the cylinder axis). Can be controlled). That is, the holder of the battery pack according to the present invention can hold the unit cells in a state where the contact points with the unit cells are dispersed over a wide range. As a result, the unit cell can be held more reliably. As a result, it is possible to hold the unit cell with one holder without aligning the two holders as in Patent Document 1. In the battery pack according to the present invention, the unit cell can be held in the same manner as described above even when two holders are combined. Note that it is not essential that all the ribs are in contact with the unit cells at the same time, and some of the ribs may not be in contact with the unit cells due to manufacturing errors of the holder and the unit cells. Further, it is not essential that the unit cell held by the holder does not move at all, and there is no problem as long as the unit cell is finely moved to the side (for example, 0.1 [mm] or less).

  The wall surface with the draft angle is tapered with a small inclination angle with respect to the cylinder axis, and is tapered toward the bottom side. Since the draft angle is given to the area where the rib does not exist as described above, even when the inclination angle of the rib with respect to the cylinder axis is very small or parallel to the cylinder axis, Demolding from the mold is relatively easy. As described above, the battery pack according to the present invention includes the case where the top slope of the rib is zero. A draft may not be provided in a part of the peripheral wall. For example, it is possible to provide a draft at the remaining portion without providing a draft at the bottom end or the opening end of the peripheral wall.

  The cross-sectional shape of the receiving tube can be, for example, a rectangular tube shape, a cylindrical shape, or the like. Further, it is not essential that the peripheral wall covers the entire peripheral surface of the unit cell. For example, in the cross section perpendicular to the cylinder axis, the peripheral wall may be C-shaped, U-shaped, U-shaped (groove shape), or the like. When the rigidity of the receiving cylinder is increased, it is desirable that the peripheral wall has an annular shape in a cross section perpendicular to the cylinder axis. Since the receiving cylinder has a cylindrical shape, it can also be referred to as a cylindrical portion.

Each rib does not need to be in contact with the side surface of the unit cell at all locations in the cylinder axis direction, and may have a portion not in contact with the unit cell. In addition, it is desirable that the rib is in contact with the unit cell at least at a portion located on the opening side of the intermediate portion of the receiving cylinder.
The plurality of ribs are distributed in the circumferential direction. Specifically, it is desirable that two or more ribs are arranged at an angular interval of 180 [°] or less in the circumferential direction of the virtual circle centered on the cylinder axis, that is, in the circumferential direction. In consideration of the stability of holding the unit cell, it is more desirable to increase the number of ribs by setting the angular interval to 120 [°] or less. It should be noted that the angular intervals of a plurality of (three or more) ribs in the circumferential direction may be unequal, in which case the maximum angular interval is 180 [°] or less (or 120 [°] or less). Is desirable. The rib has an effect of reinforcing the peripheral wall, but is provided mainly for holding the unit cell as described above. Therefore, the rib can also be referred to as a ridge, a protrusion, or a raised portion.

The receiving tube may accommodate a part of the unit cell. For example, most of the unit cells (for example, 80% or more, 90% or more of the axial length) can be accommodated, and the part protruding from the receiving tube (20%, 10%) can be covered with another constituent member. . Further, for example, the unit cells can be accommodated in half using two holders.
In the battery pack according to the present invention, at least lateral movement of the unit cell (movement of the unit cell in a direction perpendicular to the cylinder axis) is restricted by the rib. The movement of the unit cell in the cylinder axis direction may be regulated by other regulating means, for example, other constituent members such as a lead plate, or regulated by forming a bottom wall or a projection on the end of the holder. May be. As described above, the unit cell is held by the plurality of ribs by regulating the movement of the unit cell to the side.

In the battery pack according to the present invention, the following variations can be employed as an example.
In the battery pack which concerns on this invention, the said structure WHEREIN: The structure that the height of the said surrounding wall is made more than the cylinder axial direction length of the said unit cell surrounding surface is employable. By adopting such a configuration, the unit cell can be accommodated by one holder in the battery pack according to the present invention. Moreover, at the time of accommodation, the contact location of one holder and a unit cell can be hold | maintained in the state disperse | distributed to the whole unit cell surrounding surface. If the unit cell can be accommodated by one holder, the number of parts of the battery pack can be reduced, and the parts management and the manufacturing process can be simplified. In addition, when a unit cell is accommodated using two holders, in general, an extra part (screw or the like) for joining the two holders and a step for joining are required.

  Moreover, in the battery pack which concerns on this invention, the structure that the top part of the said rib is made parallel to the said cylinder axis | shaft in the said structure is employable. By adopting such a configuration, when accommodating a general unit cell in which the side surface of the unit cell is parallel to the cylinder axis, the top of the rib is brought into contact with the side surface of the unit cell as a whole in the cylinder axis direction. Can do. Therefore, the top of the rib can be brought into contact with the unit cells relatively evenly. As a result, the unit cell can be held more reliably. Moreover, it is suitable when accommodating a unit cell with one holder.

  Further, in the battery pack according to the present invention, in the above configuration, the top of the rib is a top surface facing the peripheral surface of the unit cell, and the top surface is in a cross section perpendicular to the tube axis. It is possible to adopt a configuration in which the shape is adapted to the shape of the peripheral surface. When such a configuration is adopted, for example, when the unit cell is cylindrical, the top surface is curved on an arc, and when the unit cell is square tube, for example, the top surface is flat. Is done. And since a rib and the side surface of a unit cell surface-contact, a contact area can be increased. As a result, when an impact or vibration is applied to the battery pack, the impact applied to the unit cell can be dispersed on the contact surface.

In the battery pack according to the present invention, in the above configuration, a configuration in which an angle difference between the top gradient and the draft of the peripheral wall is 0.45 [°] or more can be employed. By adopting such a configuration, it is possible to facilitate removal from the mold during holder molding.
Further, in the battery pack according to the present invention, in the above configuration, the rib may employ a configuration in which a protruding amount of the top portion from the wall surface is set to 0 at an end portion on the bottom side. By adopting such a configuration, the protruding amount of the rib is reduced, so that the peripheral wall can be brought close to the unit cell and the receiving tube can be made smaller. In addition, when the maximum value of the protrusion amount of the rib is smaller than the width of the rib (for example, the width of the top surface), the receiving tube can be made relatively small. The protruding amount of the rib can be the height of the top from the virtual wall surface when it is assumed that no rib is formed on the wall surface.

  Further, in the battery pack according to the present invention, in the above configuration, the plurality of unit cells are provided, and the plurality of receiving tubes accommodate the plurality of unit cells arranged in parallel in a state of being partitioned from each other by the peripheral wall. A configuration can be employed. In the case of adopting such a configuration, heat insulation between the unit cells can be achieved by the peripheral wall. Specifically, the radiant heat between the unit cells can be blocked by the peripheral wall. Moreover, the space | gap produced by the inclination of a wall surface exists between a surrounding wall and a unit cell, and the heat conduction between unit cells is reduced. Accordingly, when any unit cell is overheated during use (during charging / discharging), the heat is restricted from being transmitted to the surrounding unit cells.

  Further, in the battery pack according to the present invention, in the above-described configuration, each of the unit cells has a cylindrical appearance shape, and each of the plurality of receiving tubes has a regular polygonal shape in a cross section orthogonal to the tube axis. And a configuration in which the adjacent ribs are arranged side by side in a state where a part of the peripheral wall is shared, and the rib is positioned at the center of one of the sides of the regular polygon. be able to. When such a configuration is adopted, for example, a honeycomb structure or a lattice-like structure is formed by the peripheral walls of a plurality of receiving cylinders, so that a decrease in rigidity of the holder can be suppressed when the peripheral walls are thinned. Moreover, while arranging a some receiving cylinder compactly, the usage-amount of the material at the time of holder manufacture can be reduced, and cost and weight can be reduced. In addition, if the cross-sectional shape of each receiving cylinder is a regular hexagon, a square, or a regular triangle, a plurality of receiving cylinders can be arranged densely.

  Further, in the battery pack according to the present invention, in the above configuration, the one or more unit cells are a plurality of unit cells each provided with an electrode at each of both end portions in the cylindrical axis direction. On one end side of the plurality of unit cells, a lead plate that electrically connects electrodes of at least a part of the plurality of unit cells is provided, and the lead plate is arranged across the plurality of storage units, It is possible to employ a configuration in which movement of the unit cell in the cylinder axis direction is restricted by contacting the peripheral walls of the plurality of storage units. With such a configuration, for example, the movement of the unit cell in the cylinder axis direction can be restricted by a metal lead plate.

It is a model perspective view which shows the external appearance structure of the battery pack 1 which concerns on embodiment. It is a model perspective view which shows the external appearance structure of the battery pack 1 which concerns on embodiment. 2 is an exploded perspective view showing an internal configuration of the battery pack 1. FIG. 2 is an exploded perspective view showing an internal configuration of the battery pack 1. FIG. In the battery pack 1, it is a schematic perspective view which shows the holder 23 in which the some unit cell 21 was accommodated. 3 is a schematic perspective view showing an empty holder 23 in the battery pack 1. FIG. In the battery pack 1, it is a bottom view which shows the holder 23 in which the some unit cell 21 was accommodated. In the battery pack 1, it is front sectional drawing which shows the holder 23 in which the some unit cell 21 was accommodated. In the battery pack 1, it is front sectional drawing which shows the holder 23 in which the some unit cell 21 was accommodated. FIG. 3 is a schematic diagram showing an enlarged part of a cross section of a side wall 123 in the battery pack 1. 2 is a schematic perspective view showing a base 101 of a holder 23 in the battery pack 1. FIG.

Below, the form for implementing this invention is demonstrated. The embodiment used in the following description is an example used to explain the configuration, operation, and effect of the present invention in an easy-to-understand manner, and the present invention is not limited to the following form other than its essential part. It is not something to receive.
[Embodiment]
1. Configuration of Battery Pack 1 The configuration of the battery pack 1 according to the embodiment will be described with reference to perspective views showing the external appearance of FIGS. 1 and 2 and exploded perspective views of FIGS. In FIGS. 3 and 4, the direction of the viewpoint is reversed in the Z-axis direction.

As shown in FIGS. 1 and 2, the external appearance of the battery pack 1 has a rectangular parallelepiped shape, and the first and second bottom portions 3 and 5 and the side portions 7 are respectively covered with the following covering members. . The battery pack 1 includes an insulating plate 11 that covers the first bottom portion 3, a cushion member 13 that covers the second bottom portion 5, and a cushion member 15 that covers the side portions 7 as covering members.
As shown in FIGS. 3 and 4, the battery pack 1 includes a plurality of unit cells 21 having a cylindrical appearance, and a holder 23 that accommodates the plurality of unit cells 21 in parallel. The plurality of unit cells 21 are electrically and physically connected to the lead plates 25 to 29 in a predetermined combination. Thereby, a predetermined conductive path is formed and movement of the plurality of unit cells 21 in the axial direction is restricted. A protection circuit board 35 is connected to the lead plates 25 and 26 on the first bottom portion 3 side with an insulating plate 33 interposed therebetween. The cushion member 13 is adhered to the lead plates 28 and 29 on the second bottom portion 5 side by an adhesive tape 37.

The cushion member 15 has an adhesive surface on the inside, and is attached to a side portion of a holder 23 that houses a plurality of unit cells 21. The cushion member 15 is also attached to the peripheral surface of some of the unit cells 21. The insulating plate 11 is attached to the first bottom 3 of the holder 23 with an adhesive tape or an adhesive.
In the present embodiment, the plurality of unit cells 21 are lithium ion secondary batteries (nonaqueous electrolyte secondary batteries). In addition, the unit cell 21 may be a nickel hydrogen secondary battery, a nickel cadmium secondary battery, or the like. The plurality of unit cells 21 are 16 unit cells 21 having the same size. Each unit cell 21 has a positive terminal 41 (electrode) protruding at one end and a negative terminal 43 (electrode) at the other end.

2. Configuration of Holder 23 FIGS. 5 and 6 are perspective views of a holder 23 containing a plurality of unit cells 21 and an empty holder 23, respectively. Moreover, the bottom view and sectional drawing of the holder 23 which each accommodated the unit cell 21 are shown in FIGS. 8 and 9 show the AA section and BB section in FIG. 7, respectively.

The holder 23 has a substantially rectangular parallelepiped shape, and is integrally formed by injection molding. Further, the holder 23 includes a base plate 101 that is rectangular and flat in a plan view, frame portions 103 that are erected at the four corners of the main surface of the base 101, and a honeycomb that is erected on the main surface of the base 101. And a structural unit 105.
2-1. Configuration of Frame Part Each frame part 103 has a cylindrical shape, is connected to the honeycomb structure part 105, and reinforces the honeycomb structure part 105. Further, the wall 113 on the outer periphery side of the holder 23 of each frame portion 103 has a shape that follows the outer shape of the base 101, and the wall 115 on the honeycomb structure portion 105 side also serves as the side wall of the adjacent receiving cylinder 121. ing.

2-2. Configuration of Honeycomb Structure Part As shown in FIGS. 6 and 7, the honeycomb structure part 105 has a receiving cylinder having a regular hexagonal shape in cross section by a plate-like partition wall erected perpendicularly to the main surface of the base 101. A plurality of 121 are formed. In addition, the space in each receiving cylinder 121 into which the unit cell 21 is inserted has a regular hexagonal column shape, and the center line of the regular hexagonal column becomes the axis of the receiving cylinder 121, and the cylindrical axis of the accommodated unit cell 21. Matches the axis. The axial direction is parallel to the “insertion direction”.

  Each receiving cylinder 121 includes a plurality of side walls 123 arranged so as to be continuously arranged at positions corresponding to the side surfaces of a regular hexagonal column, and ribs 125 extending in the axial direction on the respective side walls 123. The plurality of receiving cylinders 121 are arranged two-dimensionally without gaps in a state where the axes of the receiving cylinders 121 are parallel to each other and adjacent ones share the side wall 123. Each receiving cylinder 121 surrounds the peripheral surface of the unit cell 21 in which a plurality of side walls 123 are inserted. Moreover, the side wall surface 131 which is the wall surface of each side wall 123 is made to oppose the surrounding surface of the unit cell 21.

  The side wall 123 is substantially rectangular and flat. As shown in FIG. 8, the side wall 123 increases as it approaches the second end portion 105 b side (opening side end portion) of the honeycomb structure portion 105 from the first end portion 105 a side (bottom end portion) of the honeycomb structure portion 105. The thickness is gradually reduced. The side wall surface 131 is inclined so that the diameter of the second end portion 105b side of the receiving cylinder 121 is increased. That is, the side wall surface 131 is provided with a draft that increases the diameter of the second end portion 105b. Due to this draft, the space in the receiving cylinder 121 is slightly tapered (tapered), so that the mold can be easily removed from the mold when the holder 23 is injection molded. In the present embodiment, the space in the receiving cylinder 121 has a truncated pyramid shape with a small inclination angle. If the cross section of the receiving cylinder is circular, the space in the receiving cylinder 121 is shaped like a truncated cone with a small inclination angle.

  Each rib 125 is disposed at the center in the width direction (direction perpendicular to the longitudinal direction) of each side wall 123 and extends in the axial direction (see FIGS. 6 and 7). FIG. 10 schematically shows an enlarged partial cross section of the side wall 123 (a range surrounded by a two-dot chain line circle). In FIG. 10, a surface obtained by cutting the region C in FIG. 7 (indicated by a two-dot chain line circle) in parallel with the BB cross section is viewed in the same direction as FIGS.

  The rib 125 is protruded to the axial line side, and its top is a top surface 133 that faces the side surface of the unit cell 21. The amount of protrusion of the top surface 133 from the side wall surface 131 is larger on the second end portion 105b side than on the first end portion 105a side. Thereby, the gradient along the axial direction of the top surface 133 of the rib 125 is made smaller than the draft of the side wall surface 131. As a result, in the state in which the unit cell 21 is accommodated, the top surfaces 133 of the plurality of ribs 125 come into contact with the peripheral surface of the unit cell 21, and the unit cell 21 is prevented from rattling. As described above, the plurality of ribs 125 restricts the unit cell 21 from moving sideways (in a direction perpendicular to the axis). The protruding amount of the top surface 133 of the rib 125 can be a height from the virtual side wall surface when it is assumed that the rib 125 is not formed on the side wall surface 131.

  The top surface 133 of the rib 125 is parallel to the axis, and the distance between the top surface 133 and the axis is the same on the first end portion 105a side and the second end portion 105b side. Thereby, the top surface 133 of the rib 125 can be brought into contact with the circumferential surface of the unit cell 21 relatively evenly in the axial direction. As a result, the holder 23 can hold the unit cell 21 more reliably. That is, the effect of regulating the lateral movement of the unit cell 21 is improved.

Further, the protruding amount of the rib 125 from the side wall surface 131 is set to 0 at the first end portion 105a. Thereby, the protrusion amount of the rib 125 whole becomes small, the side wall surface 131 can be arrange | positioned in proximity to the unit cell 21, and the dimension of the radial direction of each receiving cylinder 121 can be made small. Further, when the holder 23 is formed, it is easy to remove from the mold.
The cross-sectional shape of the rib 125 is substantially trapezoidal, and the upper side of the trapezoid is curved in an arc shape in accordance with the curvature of the unit cell 21. That is, the top surface 133 of the rib 125 is curved in an arc shape along the circumference centering on the axis line in accordance with the circumferential shape of the unit cell 21. Thereby, the unit cell 21 accommodated in the receiving cylinder 121 and the rib 125 come into surface contact, and their contact area increases. As a result, when an impact or vibration is applied to the battery pack 1, the impact applied to the unit cell 21 can be dispersed on the contact surface. Moreover, the effect of holding the unit cell 21 is also improved.

In the present embodiment, each side wall 123 is provided with a rib 125, and is held by six ribs 125 arranged at intervals of 60 ° around the axis in the central receiving cylinder 121. Further, the outer circumference (outermost circumference) receiving cylinder 121 is held by four or five ribs 125 arranged at intervals of 60 ° around the axis.
Here, in the outer periphery receiving cylinder 121 (having four ribs), movement in a specific direction toward the outside is allowed, but movement in the other side is restricted. As will be described later, the movement in the specific direction is restricted by a curved wall portion or an expansion wall portion described later, and is restricted by physical connection with the lead plate 25 or the like. Thus, the unit cell 21 can be held if the three or more ribs 125 are arranged at a maximum angular interval of 180 [°] or less in the circumferential direction of the virtual circle centered on the axis. Further, as in the case of the outer cylinder 121 (having five ribs), if the plurality of ribs 125 have a maximum angular interval of 120 [°] or less in the circumferential direction, the outward movement is restricted. Thus, the effect of holding the unit cell 21 is improved. As described above, the receiving cylinder 121 located on the outer periphery of the two-dimensional array does not include the outer peripheral side wall 123 and is partially cut away. Thus, even if the receiving cylinder 121 does not surround the entire periphery of the unit cell 21, the unit cell 21 can be held.

  As described above, the receiving cylinder 121 positioned on the outer periphery of the honeycomb structure portion 105 is partially cut away. In the receiving cylinder 121 (having four ribs) in which a part thereof is cut, the thickness in the Y-axis direction gradually increases as the outer peripheral side portion of the side wall 123 moves in the X-axis direction. The extended wall portion 135 is made. When the extension wall 135 makes the notch width of the receiving cylinder 121 smaller than the diameter of the unit cell 21 and a relatively large impact is applied to the battery pack 1, the unit cell 21 is notched of the receiving cylinder 121. It is prevented from coming off from the part. Further, in addition to the extended wall portion 135, a curved wall portion 137 that is curved in an arc shape may be provided on the side wall 123 of the receiving cylinder 121 (having four ribs) partially cut away. The curved wall portion 137 extends outward from the extended wall portion 135 along the peripheral surface of the unit cell 21, and further reduces the notch width of the receiving cylinder 121. As a result, it is more effectively prevented that the unit cell 21 is detached from the notched portion of the receiving cylinder 121 when a relatively large impact or the like is applied to the battery pack 1.

In the present embodiment, in the central receiving cylinder 121, the “circumferential wall” is constituted by six side walls 123, and the “wall surface” is constituted by six side wall surfaces 131. Further, in the outer periphery receiving cylinder 121, the “peripheral wall” is constituted by four (or five) side walls 123, and the “wall surface” is constituted by four (or five) side wall surfaces 131.
Note that the two receiving cylinders 121 adjacent to each other share one side wall 123. Conversely, the partition walls that divide the two receiving cylinders 121 adjacent to each other function as the side walls 123 of the two receiving cylinders 121, respectively. Further, the two side wall surfaces 131 formed by the shared side wall 123 are inclined in directions opposite to each other. That is, in the shared side wall 123, both side wall surfaces 131 are drafted.

  Further, two ribs 125 project in opposite directions on the side wall 123 shared by the two receiving cylinders 121 adjacent to each other. Thereby, the two ribs 125 and the one side wall 123 are linearly inserted in the gap between the two unit cells 21 adjacent to each other. As a result, it is possible to effectively prevent the two unit cells 21 from approaching each other while the rigidity of the side wall 123 is relatively small. In the honeycomb structure part 105, the plurality of receiving cylinders 121 are linearly arranged in the normal direction of the side walls 123. Therefore, for example, the separation distance of the plurality of unit cells 21 linearly arranged on the AA line in FIG. 7 can be effectively maintained.

It is not essential that the two ribs 125 are formed at the same position in the width direction of the side wall 123. For example, the rib 125 may be formed on one surface of the side wall 123 and the rib 125 may not be formed on the other surface, or two ribs 125 may be formed at different positions in the width direction of the side wall 123. Good.
A portion where the three side walls 123 intersect with each other is a thick portion 141 where the side walls 123 are thickened. Due to the thick portion 141, the strength of the honeycomb structure portion 105 is increased. Moreover, the demolding pin which pushes out the holder 23 at the time of demolding from a metal mold | die can be received by the thick part 141 (refer FIG. 6, FIG. 7).

  On the first end portion 105a side, an end holding portion 143 is formed at an end portion of the side wall 123 so as to fill a corner portion formed by two side walls 123 that intersect each other (see FIG. 6). The end holding part 143 is a curved surface 145 whose surface on the axis line side is curved in an arc shape in accordance with the curvature of the peripheral surface of the unit cell 21, and the end of the unit cell 21 is firmly attached to a relatively wide contact surface. Can be held. Note that one end holding portion 143 formed at the corner portion is formed by two side walls 123.

As described above, the holder 23 mainly holds the end portion of the unit cell 21 by the end holding portion 143 in the vicinity of the first end portion 105a, and the rib 125 between the end holding portion 143 and the second end portion 105b. The unit cell 21 is held.
In addition, if each rib 125 is in contact with the unit cell 21 at least at one location on the second end 105b side of the intermediate point between the first end 105a and the second end 105b, the end The movement of the unit cell 21 to the side can be regulated by combining the holding of the holding unit 143 and the holding by the ribs 125. Thus, the entire top surface 133 of the rib 125 does not need to be in contact with the unit cell 21 in the axial direction, but a larger contact area is desirable.

In the present embodiment, the holder 23 is formed of PC (polycarbonate: thermoplastic resin) which is a resin material. In addition, resin materials such as thermoplastic resins such as PC / ABS polymer alloy and PPS (polyphenylene sulfide), and thermosetting resins such as EP (epoxy resin) and PF (phenol resin) can be used.
The side wall 123 has a width of 10 [mm] (a dimension excluding the thick portion 141), and has a thickness of about 2.2 [mm] at the first end 105a and about 1 [mm at the second end 105b. ]. The height of the side wall 123 (the length in the Z-axis direction) is about 65 [mm].

  Further, the gradient of the side wall surface 131 with respect to the axis is set to 0.45 [°] or more, and is set to a magnitude equal to or greater than a draft angle at which the holder 23 can be removed from the mold. This is because a molding failure occurs when the slope of the side wall surface 131 is 0.4 [°] or less, and therefore, the slope of the side wall surface 131 is desirably 0.45 [°] or more. Note that the holder 23 can be molded even when the gradient of the side wall surface 131 is less than 0.45 [°].

Note that the draft angle is desirably changed according to the length of the receiving cylinder 121 (the height of the side wall 123). For example, when the receiving cylinder 121 is long, it is desirable to increase the draft, and when it is short, it is desirable to reduce the draft.
In the present embodiment, at the second end portion 105b, the width of the top surface 133 of the rib 125 is reduced to 30% or less of the width of the side wall surface 131, and the mold is removed from the mold when the holder 23 is injection molded. Has been easy. Further, the width of the top surface 133 is set to 10% or more of the width of the side wall surface 131 so that the contact area between the unit cell 21 and the rib 125 is increased. Note that the width of the top surface 133 is preferably 15% or more and 25% or less of the width of the side wall surface 131.

In the present embodiment, the upper side length La of the rib 125 at the second end portion 105b is about 2 [mm], and the lower side length Lb is about 4 [mm]. The lower side length Lb is preferably 1.5 to 2.5 [mm] longer than the upper side length La.
Furthermore, in the second end portion 105b, the inclination angle of the side surface of the rib 125 with respect to the side wall surface 131 is desirably 23 to 33 [°], and in this embodiment, is set to 26 to 30 [°].

The height of the end holding portion 143 (the length in the Z-axis direction) is about 5.4 [mm]. The draft angle of the curved surface 145 of the end holding portion 143 is set to 0.5 [°].
2-3. Configuration of Base FIG. 11 is a perspective view of the base 101. The base 101 includes a rectangular bottom wall 151, a side wall 153 erected on the peripheral edge of the bottom wall 151, and a plurality of reinforcing plates 154 that connect the bottom wall 151 and the side wall 153. Three openings 155, 156, and 157 are formed in the bottom wall 151, and the plurality of unit cells 21 and the first end portion 105a of the honeycomb structure portion 105 are partially exposed from the openings 155 and the like. . The shape of each opening 155 and the like is substantially equal to the outer shape of each of the lead plates 25 to 27, and the lead plate 25 and the unit cell 21 are electrically and physically connected as will be described later.

The opening 155 or the like partially exposes the end face of each unit cell 21. Conversely, the end face of each unit cell 21 is partially covered by the bottom wall 151, and the bottom wall 151 is also covered with the bottom wall 151. You are in contact. As a result, the movement of each unit cell 21 toward the first end portion 105a is restricted by the bottom wall 151.
A flat space surrounded by the bottom wall 151 and the side wall 153 is formed inside the base 101. The insulating plate 33 and the protection circuit board 35 are accommodated in this space. In addition, a positioning plate 161 for positioning the protection circuit board 35 is erected on the bottom wall 151. The positioning plate 161 is bent in an L shape and is addressed to the corner portion 163 of the protection circuit board 35 disposed inside the base 101.

2-4. Others On the first end 105a side of the holder 23, a meat stealing hole 167 is formed at a location where the side wall 123 intersects. In the portion where the bottom wall 151 is formed, the meat stealing hole 167 passes through the bottom wall 151.
Since the end holding portion 143 is formed, the portion where the side wall 123 on the first end portion 105a side intersects is thicker than the other portions. Since the thick portion has a larger amount of shrinkage than the thin portion, a so-called “shrink” distortion may occur. In addition, the thick part has a longer cooling time than the thin part.

The meat stealing hole 167 is formed at the time of injection molding by a molding pin extending from the mold. By reducing the amount of resin in the thick portion by the meat stealing hole 167, it is possible to suppress the occurrence of shrinkage when the resin is cured and shorten the cooling time. In the present embodiment, the meat stealing hole 167 has a diameter of 1.5 [mm] and a depth of 5 [mm] or 4 [mm].
3. Other configurations (lead plate, protection circuit board)
In the finished battery pack 1, lead plates 25, 26, 27 corresponding to the openings 155, 156, 157 are fitted. The normal lines of the main surfaces of the lead plates 25 and the like are substantially parallel to the axis (cylinder axis) (the angle between the normal lines and the axis is 10 [°] or less), and there are a plurality of main surfaces of the lead plates 25 and the like. The unit cells 21 are spread in the arrangement direction. And each lead board 25 grade | etc., Is distribute | arranged across the 2 or more receiving cylinders 121, respectively, and the positive electrode terminal 41 or the negative electrode terminal 43 of the unit cell 21 each accommodated in the 2 or more receiving cylinders 121 by spot welding etc. Bonded and electrically and physically connected. Note that the lead plate 28 and the like, and the positive electrode terminal 41 or the negative electrode terminal 43 of the unit cell 21 are also joined and electrically and physically connected on the second end portion 105b side. Due to the electrical connection between the lead plates 25 to 29 and the 16 unit cells 21, a group of four unit cells 21 connected in parallel is connected in four series and four in parallel. It is said that.

  In addition, the lead plates 25 to 27 are arranged across the plurality of receiving cylinders 121 and are in contact with the side wall 123 of the receiving cylinder 121. Therefore, the lead plate 25 or the like cannot move to the second end portion 105b side, and the movement of the unit cell 21 physically connected to the lead plate 25 or the like to the second end portion 105b side is restricted. . As a result, the holder 23 is open on the second end portion 105 b side, but the unit cell 21 does not come out of each receiving cylinder 121.

In the battery pack 1 of this embodiment, the movement of each unit cell 21 in the axial direction is restricted by the bottom wall 151 of the base 101 and the lead plates 25 to 27.
Further, each of the lead plates 25 to 29 physically connects a plurality of two-dimensionally arranged unit cells 21 disposed on the outer periphery and those disposed on the inner periphery. As a result, each lead plate 25 restricts the outward movement of the inserted unit cell 21 even when the receiving cylinder 121 located on the outer periphery of the honeycomb structure 105 is cut out as described above.

The protection circuit board 35 has a rectangular flat plate shape, and a circuit for controlling charging / discharging of the plurality of unit cells 21 is mounted on the main surface. The circuit is connected to the lead plates 25 and 26 as described above. The corner 163 of the protection circuit board 35 is provided with a terminal 165 connected to a load outside the battery pack 1, a charging device, or the like. The base 101 is formed with a notch 171 for passing a cable (lead wire) connected to the terminal 165.
4). Superiority In the battery pack 1 according to the present embodiment, ribs 125 that are in contact with the unit cells 21 are formed on the side wall 123 of the receiving cylinder 121. Even when the holder 23 (the receiving cylinder 121) is elongated in the axial direction, the ribs 125 can hold the unit cells 21 in a state where the contact portions with the unit cells 21 are dispersed over a wide range. As a result, each receiving cylinder 121 can hold the unit cell 21 more reliably, and the unit cell 21 can be accommodated and held by one holder 23.

  The holder 23 is integrally formed, and the number of parts can be reduced and the manufacturing process and parts management can be simplified as compared with the case of joining two holders. In addition, when holding the unit cell by joining two holders, the variation between components tends to be large due to an error or the like at the time of joining. It can be reduced.

In the holder 23, a honeycomb structure 105 is formed. With this honeycomb structure, while the rigidity of the holder 23 is secured, the amount of resin raw material used is reduced, thereby reducing cost and weight.
The adjacent unit cells 21 are partitioned by a side wall 123. Thereby, when one of the unit cells 21 is overheated during use of the battery pack 1 (during charging / discharging), the radiant heat is blocked between the unit cell 21 and the adjacent unit cell 21 so that the heat is transmitted. Is prevented.

  The receiving cylinder 121 located on the outer periphery of the honeycomb structure part 105 is not provided with the side wall 123 on the outer peripheral side, and is omitted. Thereby, the arrangement space of the holder 23 can be made small. Moreover, the resin raw material etc. which are used for the holder 23 are reduced, and the cost and weight are reduced. When importance is attached to the rigidity of the holder 23, it is desirable not to omit the side wall 123.

The holder 23 of the battery pack 1 is in contact with the peripheral surface of the unit cell 21 by the rib 125 and is not in close contact with the entire periphery of the unit cell 21, so that the frictional resistance when inserting the unit cell 21 is increased. Can be suppressed.
[Other matters]
In the above embodiment, the battery pack 1 includes 16 cylindrical unit cells 21. However, the shape and the number of the unit cells are not limited thereto. For example, a unit cell having a rectangular tube-like appearance can be adopted. In this case, the form of the receiving cylinder 121 may be changed correspondingly. For example, the honeycomb structure portion 105 may be a lattice-shaped structure portion to form a regular square columnar accommodation space. Further, the cross-sectional shape of the receiving cylinder 121 is not limited to a regular hexagon or a square, but may be a circle.

  In the above embodiment, four receiving cylinders 121 are arranged in the center and twelve receiving cylinders 121 are arranged on the outer periphery thereof, but the number and arrangement of the receiving cylinders 121 are not limited to this. For example, the number and arrangement of the receiving cylinders 121 can be freely changed, such as arranging a plurality of receiving cylinders 121 on the outer periphery of the 12 receiving cylinders 121. When a part of the receiving cylinder 121 is cut out as described above, it is desirable to cut out a part of the receiving cylinder 121 arranged on the outermost periphery in the arrangement of the plurality of receiving cylinders 121.

In the said embodiment, although the rib 125 was provided in all the side walls 123 of each receiving cylinder 121, it is not an essential matter. For example, the three ribs 125 may be provided on the three side walls 123 at intervals of 120 [°], and the ribs 125 may not be provided on the other side walls 123. Note that it is desirable that three or more ribs 125 are dispersedly arranged in each receiving cylinder 121.
The cross-sectional shape of the rib 125 is not limited to a substantially trapezoidal shape, and may be other shapes such as an arc shape or a triangular shape.

The length of each receiving cylinder 121 in the axial direction is set to n times the length in the axial direction of the unit cell 21 (n is an integer of 2 or more), and n unit cells 21 are accommodated in series in each receiving cylinder 121 You can also.
In the above embodiment, the draft angle is reduced in the portion where the end holding portion 143 is formed. As described above, at least one of the first end portion 105a and the second end portion 105b may include a portion having a small draft angle or a portion having no draft angle other than the rib 125. This is because if the axial direction length of the portion with a small draft is short, the holder 23 can be removed from the mold during molding.

  INDUSTRIAL APPLICABILITY The present invention is useful for realizing a battery pack including a holder that can hold a unit cell in a state where contact portions with the unit cell are widely dispersed.

1. Battery pack 21. Unit cell 23. Holder 25-27. Lead plate (first bottom side)
28, 29. Lead plate (second bottom side)
35. Protection circuit board 101. Base 103. Frame part 105. Honeycomb structure part 105a. First end 105b. Second end 121. Housing part 123. Sidewall 125. Rib 131. Side wall surface 133. Top surface 143. End holding part 151. Bottom wall 155, 156, 157. Opening

Claims (8)

A battery pack in which one or a plurality of cylindrical unit cells are housed in a holder,
The holder is provided with one or a plurality of receiving cylinders for receiving insertion in the cylinder axis direction for each unit cell,
Each receiving tube includes a peripheral wall that surrounds the inserted peripheral surface of the unit cell, and a plurality of ribs arranged in a circumferentially distributed state on the wall surface,
While the peripheral wall is provided with a draft increasing in diameter as it goes from the bottom end to the opening end on the wall,
Each rib has a top gradient along the direction in which the unit cell is inserted smaller than the draft of the peripheral wall,
The inserted unit cell is held by being in contact with the tops of the plurality of ribs.   2. The battery pack according to claim 1, wherein a height of the peripheral wall is equal to or greater than a length in a cylinder axis direction of the peripheral surface of the unit cell.   The battery pack according to claim 1, wherein a top portion of the rib is parallel to the cylindrical axis. The top of the rib is a top surface facing the peripheral surface of the unit cell,
4. The battery pack according to claim 3, wherein the top surface is formed in a cross-section perpendicular to the tube axis in accordance with a peripheral surface shape of the unit cell.   5. The battery pack according to claim 1, wherein an angle difference between the top slope and the draft of the peripheral wall is set to 0.45 degrees or more.   The battery pack according to any one of claims 1 to 5, wherein the rib has an amount of protrusion of the top from the wall surface at an end portion on the bottom side. A plurality of the unit cells,
The battery pack according to claim 1, wherein the plurality of receiving tubes accommodate the plurality of unit cells arranged in parallel in a state of being partitioned from each other by the peripheral wall. Each unit cell has a cylindrical appearance,
The plurality of receiving tubes each form a regular polygonal shape in a cross section perpendicular to the tube axis, and are arranged side by side in a state in which a part of the peripheral wall is shared by those adjacent to each other.
The battery pack according to claim 7, wherein the rib is positioned at the center of any side of the regular polygon.

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