JP6680128B2 - Battery module - Google Patents

Description

  The present invention relates to a battery module in which a plurality of cylindrical batteries are uprightly held by a battery holder.

  Conventionally, a battery module in which a plurality of battery elements are connected in series or in parallel for charging and discharging electric power is known. Such a battery module is often mounted in a device having a limited installation space, such as an electric vehicle (hybrid vehicle, electric vehicle, etc.). Therefore, further miniaturization and improvement of energy density of the battery module are desired. Therefore, a battery module using a cylindrical secondary battery with high energy density (hereinafter referred to as “cylindrical battery”) has been conventionally proposed.

  Here, the performance of the tubular battery changes depending on the temperature. Therefore, in order to suppress variations in the performance of the plurality of cylindrical batteries, it is desirable that the temperatures of the plurality of cylindrical batteries be kept uniform. Therefore, in order to make the temperatures of the plurality of cylindrical batteries evenly close to each other, the battery holder that holds the plurality of cylindrical batteries is usually made of a material having high heat conductivity, such as aluminum. By holding the tubular battery with the battery holder having excellent heat conductivity, the heat of each tubular battery is evenly distributed, and the variation in temperature of the tubular battery can be suppressed.

JP, 2013-187119, A

  However, such a battery holder having excellent heat transfer becomes a problem when the tubular battery abnormally generates heat. That is, the tubular battery may abnormally generate heat due to an abnormal reaction or the like and may rise to several hundred degrees. When the heat of the abnormal heat generation is transmitted to the peripheral cylindrical battery via the battery holder, the peripheral cylindrical battery may be thermally deteriorated in a chain manner. In other words, the tubular battery holding structure is required to have high heat conductivity when the tubular battery is normally driven, while it has a heat shielding property when the tubular battery abnormally generates heat. Is desired.

  Patent Document 1 discloses a battery holder for holding a plurality of cylindrical batteries. In this battery holder, a support having a battery holding hole, a second spacer inside each battery holding hole, and a first spacer inside the second spacer are concentrically arranged. The cylindrical battery is arranged inside the first spacer. The material of the second spacer has a lower melting point than the material of the first spacer. Therefore, when some of the tubular batteries become high in temperature, only the second spacer melts and flows out, and an air layer for heat insulation is formed between the first spacer and the battery holding hole. . As a result, the heat of some of the tubular batteries is less likely to be transferred to the other tubular batteries, and the deterioration of the other tubular batteries due to the heat can be suppressed. However, in the configuration of Patent Document 1, in addition to the support, it is necessary to further provide a spacer having a double structure, and there is a problem that the number of parts and the number of assembling steps increase.

  Therefore, it is an object of the present invention to provide a battery module that has a simple structure and can prevent deterioration of a cylindrical battery.

  The battery module of the present invention includes a plurality of cylindrical batteries having terminals formed at both ends in the axial direction and a plurality of insertion holes through which the cylindrical batteries are inserted, and a battery holder for holding the cylindrical batteries in an upright position. A lower bus bar plate which is arranged below the cylindrical battery and the battery holder and a part of which projects upward and contacts the terminal; an inner peripheral surface of the insertion hole; and an outer peripheral surface of the cylindrical battery. And a thermoplastic adhesive that fixes the cylindrical battery in the insertion hole, and is melted between the lower bus bar plate and the lower surface of the cylindrical battery. It is characterized in that a retention space for retaining the thermoplastic adhesive is formed.

  According to the present invention, since the cylindrical battery is fixed in the insertion hole with the thermoplastic adhesive, the thermoplastic adhesive melts during abnormal heat generation, and the air layer is formed between the cylindrical battery and the insertion hole. Is formed. As a result, heat of the tubular battery is less likely to be transferred to the battery holder, and thermal degradation of other tubular batteries is prevented. Further, the tubular battery separated from the battery holder due to melting of the thermoplastic adhesive falls to the lower side, but the molten thermoplastic adhesive stays in the lower stay space. The cylindrical battery that has dropped to the lower side comes into contact with the molten thermoplastic adhesive. Then, after the temperature is lowered, the staying thermoplastic adhesive is cured, so that the movement of the cylindrical battery is regulated. When the movement of the tubular battery separated from the battery holder is not regulated, the tubular battery collides with another member, which causes deterioration of the other member and noise. However, in the present invention, since the movement of the tubular battery is restricted, deterioration of other members and noise are effectively suppressed. That is, according to the present invention, it is possible to prevent the deterioration of the tubular battery while having a simple structure that does not require the addition of a dedicated component.

It is an exploded perspective view of a battery module which is an embodiment of the present invention. It is a top view of a negative electrode bus bar board. It is sectional drawing in a YZ plane of a battery module. FIG. 4 is an enlarged view of part A in FIG. 3 before melting the adhesive. FIG. 4 is an enlarged view of part A in FIG. 3 after the adhesive is melted.

  Hereinafter, a battery module 10 which is an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an exploded perspective view of a battery module 10 according to an embodiment of the present invention. 2 is a plan view of the negative electrode bus bar plate 24, and FIG. 3 is a cross-sectional view of the battery module 10 on the YZ plane. In the following description, the longitudinal direction of the battery module 10 will be referred to as the “X direction”, the axial direction of the tubular battery 12 will be referred to as the “Z direction”, and the directions orthogonal to the X direction and the Z direction will be referred to as the “Y direction”.

  The battery module 10 includes a plurality of cylindrical battery elements (hereinafter referred to as “cylindrical battery”) 12. The cylindrical battery 12 is a chargeable / dischargeable secondary battery, and is, for example, a nickel-hydrogen battery, a lithium-ion battery, or the like housed in a cylindrical case. At both ends of the cylindrical battery 12 in the axial direction, a positive electrode terminal and a negative electrode terminal, which are electrodes of the cylindrical battery 12, are provided. The battery module 10 shown in FIG. 1 has 60 cylindrical batteries 12, and the 60 cylindrical batteries 12 are arranged in an array of 4 columns and 15 rows. The sixty tubular batteries 12 are divided into groups of fifteen to form four battery groups. Fifteen cylindrical batteries 12 belonging to the same battery group are connected in parallel by a negative electrode bus bar plate 24 and a positive electrode bus bar plate 23 described later. In addition, a battery group in which 15 tubular batteries 12 are connected in parallel is connected in series to another battery group or an external output terminal by an inter-group bus bar 26 described later.

  A discharge valve (not shown) that allows release of gas generated in the tubular battery 12 is provided on the end surface of the tubular battery 12 on the negative electrode terminal side. The structure of the discharge valve is not particularly limited as long as it can be opened when the internal pressure of the cylindrical battery 12 rises. The discharge valve can be configured, for example, by locally thinning the outer case of the cylindrical battery 12. When gas is generated inside the tubular battery 12 due to overcharging, overdischarging, a short circuit, etc., and the internal pressure of the tubular battery 12 rises, the discharge valve (thin-walled portion) is broken, and the gas is fed into the tubular battery 12. It is discharged to the outside of the mold battery 12.

  Each cylindrical battery 12 is held upright with the positive electrode terminal and the negative electrode terminal aligned. In the present embodiment, the tubular battery 12 is held in an upright posture with the end surface having the negative electrode terminal facing downward (the smoke exhaust cover 20 side). The lower end of each cylindrical battery 12 is housed in an insertion hole 15 provided in the battery holder 14 and held in the battery holder 14. The battery holder 14 has a substantially plate shape, and the insertion holes 15 are two-dimensionally arranged on the plate plane. In this embodiment, the insertion holes 15 are arranged in an array of 4 columns and 15 rows, and the insertion holes 15 in the adjacent columns are arranged with a shift of half a pitch.

  Each insertion hole 15 has a round hole shape that fits with the cylindrical shape of the cylindrical battery 12. The cylindrical battery 12 is inserted into the round hole and fixed by the adhesive 60 (see FIG. 3). In the present embodiment, a thermoplastic adhesive is used as the adhesive 60 that fixes the cylindrical battery 12, but the reason will be described later in detail.

  The length of the insertion hole 15 in the direction of the central axis is sufficient to prevent the held cylindrical battery 12 from wobbling. The insertion hole 15 penetrates the battery holder 14 in the plate thickness direction, and the lower end of the cylindrical battery 12 is exposed downward. Further, the diameter of the insertion hole 15 is larger than the diameter of the cylindrical battery 12, and the distance between the inner peripheral surface of the insertion hole 15 and the outer peripheral surface of the cylindrical battery 12 is about 0.1 mm to 1 mm. A gap is formed. The battery holder 14 is made of a high heat transfer material such as aluminum. This is because the heat generated from some of the cylindrical batteries 12 is evenly distributed to reduce the variation in temperature among the cylindrical batteries 12. Since the performance and life of the tubular battery 12 change depending on the temperature, the variation in temperature of the tubular battery 12 is reduced, and the performance and life of the plurality of tubular batteries 12 are made uniform.

  The periphery of the plurality of cylindrical batteries 12 held by the battery holder 14 is covered with a protective case 16. The protective case 16 is made of a resin having an insulating property, and has a substantially box shape with a bottom completely opened. The lower end of the protective case 16 is fastened to the peripheral edge of the battery holder 14. The fastening mode is not particularly limited as long as the protection case 16 can move together with the battery holder 14 when the battery module 10 receives vibration or the like. Therefore, the protective case 16 is fastened to the battery holder 14 by fitting, screwing, welding, or the like. As will be described later, the positive electrode bus bar plate 23 is integrated with the protective case 16. Therefore, it can be said that the positive electrode bus bar plate 23 is fastened to the battery holder 14 via the protective case 16.

  The protective case 16 has a ceiling plate 30 (see FIG. 3) that is provided near the upper end of the protective case 16 and presses the positive electrode terminal side end surface of the tubular battery 12 toward the negative electrode terminal side. The ceiling plate 30 is provided with a holding opening 32 having a diameter smaller than the outer diameter of each of the arranged cylindrical batteries 12. The positive electrode terminal of the tubular battery 12 is exposed to the outside through the holding opening 32, while the end face of the tubular battery 12 is pressed toward the negative electrode terminal side by the peripheral edge of the holding opening 32. A positive electrode bus bar plate 23 is fixed to the upper surface of the ceiling plate 30. Further, various wirings (for example, voltage detection wirings and temperature detection wirings) are arranged above the protective case 16, and these wirings are covered with an insulating cover 18.

  An inlet opening 34 (see FIG. 3) and an outlet opening 36 (see FIG. 3) are formed on the peripheral surface of the protective case 16. The inlet opening 34 is an opening for allowing cooling air for cooling the tubular battery 12 to flow into the battery module 10. The outlet opening 36 is an opening for discharging the cooling air flowing into the battery module 10 to the outside. The outlet opening 36 is provided on the side wall opposite to the inlet opening 34 with the plurality of cylindrical batteries 12 sandwiched therebetween. Each of the inlet opening 34 and the outlet opening 36 is a plurality of slit holes provided in the side wall of the protective case 16. The slit holes are elongated in the height direction (Z direction), and are provided in plural at intervals in the longitudinal direction (X direction).

  A smoke exhaust cover 20 is arranged below the battery holder 14. The smoke exhaust cover 20 has a substantially boat shape with its peripheral edge rising upward. The peripheral edge of the smoke exhaust cover 20 is in close contact with the peripheral edge of the battery holder 14 to form a sealed space with the battery holder 14. This closed space functions as a smoke exhaust space 28 through which the gas released from the tubular battery 12 flows. The gas released from the cylindrical battery 12 to the smoke exhaust space 28 is exhausted through an exhaust hole 62 formed at the end of the negative electrode bus bar assembly 25 and an exhaust passage 64 formed at the end of the battery holder 14 (see FIG. 1). ) Is discharged to the outside of the battery module 10 and guided to an appropriate position by a duct or the like.

  Like the protective case 16, the smoke exhaust cover 20 is also fastened to the battery holder 14. This fastening mode is also not particularly limited as long as the smoke exhaust cover 20 can move together with the battery holder 14 when the battery module 10 receives vibration or the like. In the present embodiment, the smoke exhaust cover 20 is screwed and fastened to the battery holder 14 via a fastening portion 20a extending from the peripheral edge of the smoke exhaust cover 20 toward the battery holder 14. Since the periphery of the negative electrode bus bar assembly 25 is sandwiched between the smoke exhaust cover 20 and the battery holder 14, it can be said that the negative electrode bus bar assembly 25 is fastened to the battery holder 14 via the smoke exhaust cover 20.

  A negative electrode bus bar assembly 25 is provided below the cylindrical battery 12. The negative electrode bus bar assembly 25 is formed by covering the same number (four in this embodiment) of negative electrode bus bar plates 24 as the battery groups with a cover cover 43 made of resin and integrating them. The four negative electrode bus bar plates 24 are integrated with each other by the covering cover 43 while keeping the insulation with being spaced apart from each other.

  Each negative electrode bus bar plate 24 electrically connects the negative electrodes of the fifteen cylindrical batteries 12 forming one battery group to each other. The negative electrode bus bar plate 24 is a flat plate member made of a conductive material such as copper. The negative electrode bus bar plate 24 is provided with through openings 40 corresponding to the arranged cylindrical batteries 12. One through opening 40 is provided for each cylindrical battery 12, and the lower end surface of the corresponding cylindrical battery 12 is exposed to the smoke exhaust space 28. The through opening 40 has a diameter slightly smaller than the outer diameter of the cylindrical battery 12. The exhaust valve provided in the cylindrical battery 12 is exposed to the smoke exhaust space 28 through the through opening 40. The gas discharged from the cylindrical battery 12 passes through the through opening 40 and reaches the smoke exhaust space 28.

  The peripheral edge of the through opening 40 slightly rises toward the upper side, that is, toward the cylindrical battery 12 side to form the dam portion 48 (see FIG. 4). This is to prevent the adhesive 60 melted by high heat from flowing out, which will be described later.

  From the peripheral edge of the through opening 40, a connecting piece 42 that extends upward and contacts the negative electrode terminal of the cylindrical battery 12 extends. The connection piece 42 is in the shape of a leaf spring having appropriate elasticity, and is inclined so as to approach the negative electrode terminal of the tubular battery 12 as it approaches the tip. Then, the tips of all the connection pieces 42 come into contact with the negative electrode terminals of the corresponding cylindrical batteries 12 to electrically connect the negative electrode terminals of the 15 cylindrical batteries 12 to each other.

  The covering cover 43 covers the negative electrode bus bar plate 24 while avoiding the through openings 40. Therefore, the covering cover 43 is formed with a round hole 44 concentric with the through opening 40. The inner diameter of the round hole 44 on the upper side of the negative electrode bus bar plate 24 is larger than that of the insertion hole 15 formed in the battery holder 14. Therefore, when the negative electrode bus bar assembly 25 is arranged below the battery holder 14, the covering cover 43 contacts the bottom surface of the battery holder 14 but does not contact the bottom surface of the tubular battery 12. Then, a space having a thickness corresponding to the thickness of the cover 43 is formed between the bottom surface of the cylindrical battery 12 and the negative electrode bus bar plate 24. This space functions as a retention space 46 in which the melted adhesive 60 is retained.

  A positive electrode bus bar plate 23 having a conductive plate similar in shape to the negative electrode bus bar plate 24 is disposed above the cylindrical battery 12. The positive electrode bus bar plate 23 is incorporated in the protective case 16 and integrated with the protective case 16. The positive electrode bus bar plate 23 also electrically connects the positive electrodes of the fifteen cylindrical batteries 12 forming one battery group. The negative electrode bus bar plate 24 and the positive electrode bus bar plate 23 connect 15 cylindrical batteries 12 forming one battery group in parallel.

  The four battery groups are connected in series by the inter-group bus bar 26. Specifically, the inter-group bus bar 26 electrically connects the positive electrode bus bar plate 23 connected to one battery group and the negative electrode bus bar plate 24 connected to another adjacent battery group. The inter-group bus bar 26 is a substantially flat plate-shaped member made of a conductive material such as copper, and is arranged outside the protective case 16 as shown in FIGS. 1 and 3. The inter-group bus bar 26 is also connected to the positive electrode bus bar plate 23 of one battery group at its upper end and to the negative electrode bus bar plate 24 of the adjacent battery group at its lower end, and also in the X direction as it advances in the Z direction. It has a substantially parallelogram shape that advances.

  Here, as described above, in the present embodiment, a thermoplastic adhesive is used as the adhesive 60 for fixing the tubular battery 12 to the insertion hole 15 of the battery holder 14. The reason for using such a thermoplastic adhesive will be described.

  It is known that the cylindrical battery 12 has its performance and life changed depending on the temperature. Therefore, in order to suppress variations in the temperature and life of the tubular batteries 12, it is desirable that the temperatures of the plurality of tubular batteries 12 be uniform. Therefore, in the present embodiment, the tubular batteries 12 are held by the battery holders 14 having excellent heat conductivity, and the heat from each tubular battery 12 is evenly distributed through the battery holders 14.

  However, the battery holder 14 having excellent heat transfer becomes a problem when the tubular battery 12 abnormally generates heat. That is, in the cylindrical battery 12, an abnormal chemical reaction may occur inside, and a large amount of gas may be generated. When the pressure inside the battery case becomes equal to or higher than a certain level due to the generation of gas, the gas is released from the exhaust valve. However, until just before the gas is released, the temperature of the cylindrical battery 12 rapidly rises to several hundreds of degrees as the pressure rises. When the heat of the tubular battery 12 that has caused such abnormal heat generation is quickly transmitted to the other tubular batteries 12 via the battery holder 14, the other tubular batteries 12 are thermally deteriorated in a chain. In other words, the holding structure for the tubular battery 12 is desired to have high heat conductivity when the tubular battery 12 is normally driven, while it is shielded when the tubular battery 12 abnormally generates heat. It is desired to have heat resistance.

  In order to meet such a demand, in the present embodiment, a thermoplastic adhesive is used as the adhesive 60 for fixing the tubular battery 12. The thermoplastic adhesive melts when the temperature exceeds a predetermined melting temperature, and then solidifies when the temperature decreases. A case where the cylindrical battery 12 is fixed using the thermoplastic adhesive 60 will be described with reference to FIGS. 4 and 5. 4 and 5 are enlarged views in the vicinity of the negative electrode terminal (enlarged view of portion A in FIG. 3). FIG. 4 is a view before the adhesive 60 is melted, and FIG. 5 is a view after the adhesive 60 is melted. It is a figure.

  When the tubular battery 12 is normally driven, as shown in FIG. 4, the tubular battery 12 is located between the tubular battery 12 and the insertion hole 15 and is fixed to the insertion hole 15. The heat generated in each cylindrical battery 12 is transferred to the battery holder 14 via the adhesive 60 and is evenly distributed to the other cylindrical batteries 12.

  On the other hand, when the cylindrical battery 12 abnormally heats up and rises to several hundred degrees, the adhesive 60 around the abnormally heated cylindrical battery 12 melts. The melted adhesive 60 flows out below the battery holder 14 as shown in FIG. As a result, an air layer is formed between the outer peripheral surface of the cylindrical battery 12 and the inner peripheral surface of the insertion hole 15. This air layer functions as a heat shield layer that inhibits heat transfer from the tubular battery 12 to the battery holder 14. As a result, the heat transfer of the heat of the tubular battery 12 that has abnormally generated heat is effectively blocked, and the thermal deterioration of the other tubular batteries 12 can be effectively prevented.

  By the way, as described above, in this embodiment, the retention space 46 is formed between the cylindrical battery 12 and the negative electrode bus bar plate 24. Further, the peripheral edge of the through opening 40 rises upward so as to prevent the melted adhesive 60 from flowing out, and forms a dam portion 48 (see FIG. 4). As a result, the adhesive 60 melted due to the abnormal heat generation stays in the staying space 46.

  Further, the cylindrical battery 12 in which the adhesive 60 melts falls downward due to its own weight, that is, toward the negative electrode bus bar plate 24 side. Since the molten adhesive 60 remains on the negative electrode bus bar plate 24, the bottom surface of the dropped cylindrical battery 12 comes into contact with the accumulated adhesive 60.

  When gas is released from the tubular battery 12 in this state, the temperature of the tubular battery 12 rapidly decreases. Then, when the temperature drops below a certain level, the adhesive 60 cures again while being in contact with the bottom surface of the cylindrical battery 12. Then, the adhesive 60 is completely cured, so that the tubular battery 12 is fixed to the negative electrode bus bar plate 24. As a result, the movement of the cylindrical battery 12 separated from the insertion hole 15 is restricted. Here, when the movement of the tubular battery 12 is not restricted and the tubular battery 12 can freely move with respect to other members such as the negative electrode bus bar plate 24 and the battery holder 14, the tubular battery 12 is not included in the other members. By vibrating and colliding with respect to each other, noise is generated and other members are deteriorated. However, in the present embodiment, the cylindrical battery 12 separated from the battery holder 14 is fixed to the negative electrode bus bar plate 24 by the re-solidified adhesive 60 and its movement is restricted, so that deterioration of other members and noise. Can be effectively prevented.

  The type of the adhesive 60 used here is not particularly limited as long as it is thermoplastic. However, the melting point of the adhesive 60 must be sufficiently higher than the maximum temperature of the tubular battery 12 during normal driving. For example, when it is known that the temperature of the tubular battery 12 does not exceed 70 degrees during normal driving, it is desirable to use an adhesive having a melting point sufficiently higher than 70 degrees. In this embodiment, a polypropylene-based adhesive having a melting point of about 150 degrees and starting to soften at about 100 degrees is used.

  As is clear from the above description, in the present embodiment, a thermoplastic adhesive is used as the adhesive 60 and the configuration of the negative electrode bus bar assembly 25 is slightly changed to prevent heat transfer during abnormal heat generation. There is. In other words, in the present embodiment, no new component is added to prevent heat transfer during abnormal heat generation. As a result, it is possible to effectively prevent the deterioration of the cylindrical battery 12 with a simple configuration that does not cause an increase in the number of parts and deterioration of the assembling property. Further, in the present embodiment, the cylindrical battery 12 separated from the battery holder 14 due to abnormal heat generation is fixed to the negative electrode bus bar plate 24 using the melted adhesive 60. As a result, even after the separation, the movement of the separated cylindrical battery 12 can be restricted, and deterioration of other members and noise can be effectively suppressed.

  Note that the configuration described so far is an example, and if a thermoplastic adhesive is used as the adhesive 60 and the retention space 46 is formed between the cylindrical battery 12 and the negative electrode bus bar plate 24, other configurations are possible. The configuration may be changed as appropriate. For example, in the present embodiment, the upper end of the weir 48 is set lower than the bottom surface of the battery holder 14 in order to avoid contact between the adhesive 60 melted and stayed in the retention space 46 and the bottom surface of the battery holder 14. ing. However, if some kind of heat insulating mechanism is provided on the bottom surface of the battery holder 14, the upper end of the dam portion 48 and the bottom surface of the battery holder 14 may have the same height. Further, the number of cylindrical batteries 12 and the shapes of various members may be changed as appropriate.

10 battery module, 12 cylindrical battery, 14 battery holder, 15 insertion hole, 16 protective case, 18 insulating cover, 20 smoke exhaust cover, 23 positive electrode bus bar plate, 24 negative electrode bus bar plate, 25 negative electrode bus bar assembly, 26 inter-group bus bar, 28 smoke exhaust space, 30 ceiling plate, 32 holding opening, 34 inlet opening, 36 outlet opening, 40 through opening, 42 connecting piece, 43 coating cover, 44 round hole, 46 retention space, 48 dam portion, 60 adhesive, 62 Exhaust hole, 64 exhaust passage.

Claims (1)

A plurality of cylindrical batteries with terminals formed at both ends in the axial direction,
A plurality of insertion holes for inserting the tubular batteries are formed, and a battery holder for uprightly holding the plurality of tubular batteries,
A lower bus bar plate which is arranged below the cylindrical battery and the battery holder, a part of which protrudes upward and contacts the terminal,
A thermoplastic adhesive that is applied between the inner peripheral surface of the insertion hole and the outer peripheral surface of the cylindrical battery to fix the cylindrical battery in the insertion hole,
Equipped with
A retention space is formed between the lower bus bar plate and the lower surface of the cylindrical battery, in which the molten thermoplastic adhesive is retained.
A battery module characterized by the above.