JP2019110003A - Battery case - Google Patents

Abstract

To provide a battery case which is lightweight but has excellent rigidity and heat resistance.SOLUTION: A battery case comprises a side cover 21 and a lower case 23. The lower case 23 has a sandwich structure in which a first plate 231 and a second plate 232 are sandwiching a core member 233. In the sandwich structure of the lower case 23, the first plate 231 is disposed on a battery (battery module 10a) side. The core member 233 comprises resin. The second plate 232 is a metal plate. The second plate 232 and the side cover 21 are joined. A flow channel(s) F1 is formed inside the first plate 231.SELECTED DRAWING: Figure 3

Description

  The present disclosure relates to a battery case, and more particularly to the structure of a battery case bottom.

  A panel having a sandwich structure (hereinafter referred to as "sandwich panel") is known as a member constituting a hull. JP-A-2010-179669 (Patent Document 1) discloses a sandwich panel having a sandwich structure in which a core material is sandwiched between a pair of FRP (fiber reinforced plastic) plates.

JP, 2010-179669, A

  By the way, in an automobile, the fuel consumption rate (fuel consumption per unit travel distance) gets worse as the vehicle gets heavier, so there is a demand for weight reduction of devices (such as batteries) mounted on the vehicle. The battery case of the in-vehicle battery is formed by sheet metal processing of a metal plate (for example, an aluminum alloy plate). If the metal plate is too thin, sufficient strength (stiffness) for the battery case can not be secured, and there is a limit to the weight reduction of the battery case.

  Therefore, the inventor of the present application considered using a sandwich panel for the battery case of the on-board battery. However, when the above-mentioned sandwich panel described in Patent Document 1 is used as it is in a battery case, it is difficult to secure sufficient heat resistance for the battery case with an FRP plate. In vehicles (electric vehicles, hybrid vehicles, etc.), the temperature fluctuation outside the battery case becomes large, so the heat resistance of the FRP plate particularly on the outer side (opposite side of the battery) of the pair of FRP plates becomes a problem.

  The present disclosure has been made to solve the above-described problems, and an object of the present disclosure is to provide a battery case that is lightweight and yet has excellent rigidity and heat resistance.

  The battery case of the present disclosure includes a side wall and a bottom. The bottom portion has a sandwich structure in which the first plate and the second plate sandwich the core material. In this sandwich structure, a first plate is disposed on the battery side. The core material contains a resin. The second plate is a metal plate. The bottom second plate and the side wall are joined. And a flow path is formed in at least one place among the inside of the 1st board, between the 1st board and the core material, and the inside of the core material.

  In the above configuration, the bottom of the battery case has a sandwich structure. And since the core material of this sandwich structure contains resin, it is lighter than metal. Such a sandwich structure makes it possible to reduce the weight of the bottom. In order to reduce the weight of the bottom portion, it is particularly preferable that the core material contains a foamed resin or a honeycomb structure made of resin.

  Moreover, the 2nd board (metal board) which has the heat resistance superior to plastics (FRP etc.) is arrange | positioned on the outer side (the opposite side to a battery) of the said sandwich structure. Thereby, the heat resistance of the battery case against the rise of the environmental temperature outside the battery case is improved.

  Further, the side wall portion and the bottom portion are separated, so that it is easy to make only the bottom portion of the side wall portion and the bottom portion into a sandwich structure. Furthermore, by bonding the second plate (metal plate) having high strength (rigidity) to the side wall portion of the battery case, the reduction in rigidity of the battery case at the bonding portion is suppressed, and the entire battery case after bonding has high rigidity. Become to have. In order to give sufficient rigidity to the second plate, the second plate is preferably formed of a material having a high Young's modulus. From the viewpoint of rigidity and heat resistance, the second plate is particularly preferably a steel plate.

  The bonding may be mechanical bonding (rivet bonding, screw bonding, caulking bonding, etc.), metallurgical bonding (welding, welding, etc.), or bonding using an adhesive. Good. In the case where not only the second plate but also the side wall portion is formed of metal, the mechanical joining of the second plate and the side wall portion facilitates the assembly and disassembly of the battery case. After mechanically joining the second plate and the side wall, the gap between the members may be filled with an adhesive.

  In addition, the temperature of the battery and its periphery is set using the flow path formed in the vicinity of the battery (that is, inside the first plate, between the first plate and the core material, and inside the core material). It becomes possible to adjust. By flowing a heat medium (such as a refrigerant) in the flow path, the temperature around the flow path can be adjusted. For example, in the sandwich structure described above, members other than the second plate (metal plate) do not necessarily have excellent heat resistance. In particular, since the core material contains a resin, the heat resistance tends to be low. However, even if the heat resistance of each of the first plate and the core material itself is low, the first plate and the core material are cooled by flowing a low-temperature heat medium into the above-mentioned flow path to It is possible to prevent the core material from becoming hot. In addition, when the environmental temperature is low, a high temperature heat transfer medium may be made to flow through the above-mentioned flow path to warm the battery and its surroundings.

  In order to enhance the efficiency of the above-mentioned temperature control, it is preferable that the first plate is formed of a material having high thermal conductivity (such as copper or aluminum).

  Hereinafter, the space between the first plate and the core member may be referred to as a “first core boundary”, and the space between the core member and the second plate may be referred to as a “second core boundary”. In order to flow the heat medium to the flow path to control the temperature of the battery efficiently, it is particularly preferable that the flow path is formed in either one of the inside of the first plate and the first core boundary. The efficiency of the temperature control is enhanced by the heat medium passing near the battery. That is, the temperature control efficiency is higher when the heat medium passes through the first core boundary than when the heat medium passes through the second core boundary. The heat medium may be gas or liquid.

  According to the present disclosure, it is possible to provide a battery case having excellent rigidity and heat resistance while being lightweight.

FIG. 1 schematically shows a vehicle to which a battery case according to an embodiment of the present disclosure is applied. It is a figure which shows the internal structure of the battery shown in FIG. It is the III-III sectional view of FIG. It is a figure which shows the planar shape of the 1st board and 2nd board which were shown in FIG. It is a figure for demonstrating the method to crimp and join the side cover shown in FIG. 3, and the 2nd board of lower case. It is a figure for demonstrating the method to join two boards and form the 1st board of a lower case. It is a figure which shows the 1st board formed by the method of FIG. It is a figure for demonstrating the modification of the method of forming the sandwich structure of a lower case. It is a figure for demonstrating the modification of the joining method of a lower case and a side cover. It is a figure which shows the example in which the flow path was formed between the 1st board and core material in sandwich structure. It is a figure which shows the example in which the flow path was formed inside the core material in sandwich structure.

  Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding portions are denoted by the same reference characters and description thereof will not be repeated.

  In each figure, among the X axis, Y axis, and Z axis orthogonal to one another, the X axis indicates the vehicle width direction of the vehicle, the Y axis indicates the longitudinal direction of the vehicle, and the Z axis indicates the height direction of the vehicle . Hereinafter, “+” is indicated in one direction indicated by the arrows of the X axis, Y axis, and Z axis, and “−” is indicated in the opposite one direction. Also, the + Y direction may be referred to as “forward”, the −Y direction as “backward”, the + Z direction as “upper”, and the −Z direction as “down”.

  Below, the example which the battery case according to this embodiment is applied to the battery of an electric vehicle is demonstrated. However, the application target of the battery case is not limited to the battery of the electric vehicle, and is optional. For example, the battery case may be a battery of a hybrid vehicle, or may be a stationary battery. Also, the type of the battery is optional including the unit cell / assembled battery, and for example, the following battery case may be applied to the fuel cell.

  FIG. 1 is a view schematically showing a vehicle 100 to which a battery case according to this embodiment is applied.

  Referring to FIG. 1, vehicle 100 includes a vehicle body 101, front wheels 102, rear wheels 103, a motor generator (hereinafter referred to as "MG (Motor Generator)") 104, and a power control unit (hereinafter referred to as "PCU"). (Power Control Unit) 105 and the battery 10 are provided. The front wheel 102 is provided forward of the center of the vehicle body 101 in the front-rear direction, and the rear wheel 103 is provided rearward of the center of the vehicle body 101 in the front-rear direction. Vehicle 100 is configured to travel using power stored in battery 10.

  MG 104 is, for example, a three-phase alternating current rotating electric machine. The output torque of the MG 104 is transmitted to the drive wheels (the front wheels 102 and / or the rear wheels 103) via a power transmission gear configured by a reduction gear or the like. The MG 104 can also generate electric power by the rotational force of the drive wheel at the time of regenerative braking operation of the vehicle 100.

  The PCU 105 includes an inverter and a converter (both not shown). When the battery 10 is discharged, the converter boosts the voltage supplied from the battery 10 and supplies it to the inverter. The inverter converts the DC power supplied from the converter into AC power to drive the MG 104. On the other hand, at the time of charging of battery 10, the inverter converts AC power generated by MG 104 into DC power and supplies the DC power to the converter. The converter steps down the voltage supplied from the inverter and supplies it to the battery 10.

  The battery 10 is fixed to a lower surface (under the floor) of a floor panel that constitutes a part (underbody) of the vehicle body 101 in a state of being exposed outside the vehicle. The shape of the battery case of the battery 10 can be made to conform to the shape below the floor of the vehicle body 101. In the battery 10, the width direction of the battery case is the vehicle width direction (X axis) of the vehicle 100, the length direction of the battery case is the front and back direction (Y axis) of the vehicle 100, and the height direction of the battery case is the vehicle 100 It is mounted on the vehicle 100 so as to coincide with the height direction (Z axis).

  Hereinafter, the structure of the battery case of the battery 10 will be described using FIGS. 2 to 7. FIG. 2 is a view showing an internal structure of the battery 10. For convenience of explanation, FIG. 2 shows the structure of the battery 10 as viewed from above with the upper cover of the battery case omitted. FIG. 3 is a cross-sectional view taken along the line III-III in FIG. In FIG. 3, the upper cover of the battery case is also illustrated.

  Referring to FIGS. 2 and 3, battery 10 includes eight battery modules 10 a to 10 h. Each battery module is configured to include an assembled battery and its accessories. For example, as shown in FIG. 3, the assembled battery is configured by alternately stacking a plurality of cells 11 and a plurality of spacers 12 in the X direction. The plurality of cells 11 constituting the assembled battery are arranged while reversing the direction one by one, and the positive electrode terminal of one cell 11 and the negative electrode terminal of another adjacent cell 11 are electrically connected by the bus bar 13 It is connected. Thus, the plurality of cells 11 are electrically connected in series. In addition, the connection aspect of the cell 11 in an assembled battery is arbitrary, for example, several cell 11 may be electrically connected in parallel.

  For example, a lithium ion battery can be employed as the cell 11. However, a secondary battery (for example, a nickel hydrogen battery) other than a lithium ion battery may be adopted as the cell 11. As an example of the attachment of the assembled battery, a connection member (a bus bar 13, a harness etc.) for electrically connecting the plurality of cells 11, a connection member (restraint plate for mechanically connecting the plurality of cells 11, Restraint band etc., a holder (resin frame etc.) for holding each cell 11, a sensor for detecting the state (current, voltage, temperature etc.) of each cell 11, a relay for relaying between each cell 11 and an external device (Other than the bus bar 13 is not shown).

  The battery (battery modules 10a to 10h) is housed in the housing portion 20 of the battery case. The housing portion 20 of the battery case includes the side covers 21 and 22 (side walls of the battery case), the lower case 23 (bottom of the battery case), a plurality of reinforcements 40 (reinforcement members), and an upper cover 33 (battery case lid) Part). On the upper surface of the lower case 23, five reinforcements 40 extending in the X direction are provided. The upper surface of the lower case 23 is divided into four areas by the reinforcement 40, and two battery modules are arranged in each area. The number of reinforcements is arbitrary. Also, instead of or in addition to the reinforcement extending in the X direction, the reinforcement extending in the Y direction may be used. If you do not need reinforcement, you may omit reinforcement.

  A front cover 31 (a front surface of the battery case) and a back cover 32 (a rear surface of the battery case) are attached to the front and the rear of the housing portion 20 of the battery case, respectively. The method of joining the housing portion 20 of the battery case to each of the front cover 31 and the back cover 32 is optional, and may be mechanical joining (for example, riveting) or metallurgical joining (for example, welding) It may be. The front cover 31, the back cover 32, and the upper cover 33 are formed of a metal plate (for example, an aluminum alloy plate). These covers can be formed by sheet metal processing. In order to reduce the weight of the battery case, at least one of the front cover 31, the back cover 32, and the upper cover 33 may be formed of resin.

  A refrigerant inlet 31 a is provided in a portion (chamber portion) covered by the front cover 31 in the space in the battery case. The refrigerant supplied from the refrigerant supply device (not shown) is introduced into the battery case through the refrigerant inlet 31a. Thus, the battery modules 10a to 10h and the like in the battery case are cooled. Further, the refrigerant supplied from the refrigerant supply device also flows to the flow path (flow path F1 etc.) of the lower case 23 described later. Thereby, battery modules 10a-10h and lower case 23 are cooled. As the refrigerant, for example, air (cold air) can be adopted.

  The back cover 32 is provided with a duct 32 a in communication with the space in the battery case. The flow path (flow path F1 etc.) of the lower case 23 described later is also in communication with the duct 32a. The duct 32a functions as an outlet for the refrigerant. That is, the refrigerant supplied from the above-described refrigerant supply device is a space within the battery case (a space surrounded by the side covers 21 and 22, the lower case 23, the front cover 31, the back cover 32, and the upper cover 33) and the lower case 23 Through the flow path of the air flow to the duct 32a. The refrigerant discharged to duct 32a is discharged to the outside of vehicle 100 through, for example, a filter (not shown).

  The battery 10 is assembled, for example, in the following procedure. First, the battery modules 10a to 10h are placed on the lower case 23. Each battery module may be assembled in the lower case 10. Subsequently, side covers 21 and 22 and upper cover 33 are attached to cover battery modules 10a to 10h on lower case 23 to form housing portion 20 of the battery case. Attach the front cover 31 and the back cover 32. Thereby, the battery case which accommodates a battery (battery module 10a-10h) is obtained. Then, the battery 10 is completed by attaching necessary accessories (such as the duct 32a) to the battery case.

  In this embodiment, the housing portion 20 of the battery case, the front cover 31 and the back cover 32 which are separated from each other are joined. However, the present invention is not limited to this, and may have a seamless structure as needed. For example, the bottom of the front cover 31, the bottom of the back cover 32, and the lower case 23 may be integrally formed. Further, the side wall portion of the front cover 31, the side wall portion of the back cover 32, and the side covers 21 and 22 may be integrally formed. Further, the lid of the front cover 31, the lid of the back cover 32, and the upper cover 33 may be integrally formed.

  By the way, since the fuel consumption rate becomes worse as the vehicle 100 becomes heavier, weight reduction of the battery 10 mounted on the vehicle 100 (and consequently weight reduction of the battery case) is required. However, it is not easy to reduce the weight of the battery case while maintaining sufficient rigidity and heat resistance for the battery case.

  For example, if the thickness of the plate of the battery case is made too thin to reduce the weight of the battery 10, sufficient strength (rigidity) for the battery case can not be secured. Further, the battery 10 is fixed in a state of being exposed outside the vehicle (see FIG. 1). For this reason, the battery case of the battery 10 is easily heated by the influence of radiant heat from the road surface. Further, when the vehicle 100 travels (especially when traveling on a rough road), load from the road surface (so-called road surface input) is added to the battery case of the battery 10, and local buckling tends to occur.

  Therefore, in this embodiment, by adopting lower case 23 having a sandwich structure as shown in FIG. 3 at the bottom of the battery case, a battery case having excellent rigidity and heat resistance while realizing light weight is realized. ing.

  Although the details will be described later, the core material 233 of the sandwich structure contains a resin. Since the resin is lighter than metal, the above-described sandwich structure makes it possible to reduce the weight of the lower case 23. In order to obtain high rigidity with a solid metal plate, it is necessary to thicken the plate material of the metal plate, so it is considered that the solid metal plate is heavier than the lower case 23 (sandwich panel) in comparison with the same rigidity. Moreover, the 2nd board 232 which is a metal plate is arrange | positioned on the outer side (-Z direction) of the said sandwich structure. Since the metal has heat resistance superior to that of plastic (FRP or the like), the second plate 232 improves the heat resistance of the battery case with respect to radiant heat from the road surface. Further, since the side covers 21 and 22 and the lower case 23 are divided, it becomes easy to make only the lower case 23 into the sandwich structure described above. Furthermore, the second plate 232 having high strength (rigidity) is joined to the side covers 21 and 22. Thereby, the rigid fall of the battery case in a junction part is suppressed, and the whole battery case after joining comes to have high rigidity. As a result, the load can be easily dispersed throughout the battery case, and the durability of the battery case to road surface input is improved.

  Further, in the battery case according to this embodiment, a plurality of flow paths F1 are formed in the inside of the first plate 231. For this reason, the temperature of battery modules 10a-10h and its periphery can be adjusted using the flow path F1 formed in battery vicinity (under battery modules 10a-10h). The first plate 231 and the core material 233 can be cooled by flowing the refrigerant into the flow path F1, and the first plate 231 and the core material 233 can be prevented from having a high temperature.

  Hereinafter, the above-described structure of the battery case according to this embodiment will be described in detail with reference to FIG. Referring to FIG. 3, lower case 23 constituting the bottom of the battery case has a sandwich structure in which first plate 231 and second plate 232 sandwich core material 233. In this sandwich structure, the first plate 231 is disposed on the battery (for example, battery module 10 a) side. The battery modules 10 a to 10 h shown in FIG. 2 are all mounted on the upper surface of the first plate 231.

  Core material 233 is made of, for example, a foamed resin. Examples of the foamed resin include foamed polyurethane, foamed polystyrene, and foamed polyolefin (foamed polypropylene and the like). Since the foamed resin is light, the weight reduction of the lower case 23 can be achieved by the core material 233 containing the foamed resin. Further, since the foamed resin has a low thermal conductivity, the core material 233 easily suppresses the external heat input. In order to give the lower case 23 sufficient rigidity, it is preferable to form the core material 233 of a material having a Young's modulus of 1 GPa or more.

  For example, a core material 233 having a desired shape (for example, a rectangular flat plate shape) is obtained by a known resin molding method, and the first plate 231 and the second plate 232 are joined to the upper surface and the lower surface of the core material 233, respectively. Thus, the lower case 23 having the sandwich structure as described above is obtained. The core material 233 and the first plate 231 and the second plate 232 can be bonded, for example, with an adhesive.

  The first plate 231 is, for example, an aluminum alloy plate. In order to disperse heat by the first plate 231 to prevent local heating, the first plate 231 is preferably formed of a material having a thermal conductivity of 50 W / m · K or more. The second plate 232 is, for example, a steel plate. In order to give sufficient rigidity to the second plate 232 with a thin plate material, it is preferable to form the second plate 232 with a material having a Young's modulus of 100 GPa or more. In this embodiment, the first plate 231 and the second plate 232 are both metal plates, the first plate 231 has a higher thermal conductivity than the second plate 232, and the second plate 232 is a first plate. It has a Young's modulus higher than 231.

  FIG. 4 is a view showing a planar shape of the first plate 231 and the second plate 232. As shown in FIG. In order to compare the 1st board 231 and the 2nd board 232, in FIG. 4, only the 1st board 231 and the 2nd board 232 are shown.

  Referring to FIG. 4, the dimensions in the length direction (Y axis) are substantially the same for the first plate 231 and the second plate 232. However, the dimension in the width direction (X axis) of the second plate 232 is larger than that of the first plate 231. The second plate 232 has a portion (hereinafter, referred to as “outer edge portion”) extending outward (side cover 21 and 22 side) of both ends in the width direction of the first plate 231. The outer edge E1 of the second plate 232 is located closer to the side cover 21 (FIG. 2) than the first plate 231. The outer edge E2 of the second plate 232 is located closer to the side cover 22 (FIG. 2) than the first plate 231.

  Referring again to FIG. 3, the side cover 21 integrally includes an upper portion 21 a, a lower portion 21 b, and a caulking portion 21 c. The upper portion 21 a of the side cover 21 is a portion above the boundary between the first plate 231 and the core member 233 (the lower surface of the first plate 231 or the upper surface of the core member 233), and the lower portion 21 b is a first portion. It is a portion below the boundary between the plate 231 and the core member 233. The lower portion 21b of the side cover 21 is mounted on the upper surface of the outer edge portion E1 of the second plate 232, and has a portion (hereinafter, may be referred to as a "side protruding portion") protruding toward the core material 233 side. The side protrusion is sandwiched between the first plate 231 and the second plate 232, and is in contact with all of the first plate 231, the second plate 232, and the core material 233.

  The side cover 21 is formed of a metal (for example, an aluminum alloy). The side cover 21 has a hollow block structure. That is, the cavities R11 and R12 are formed in the upper portion 21a, and the cavity R13 is formed in the lower portion 21b. By forming the cavities R11 to R13, the weight of the side cover 21 can be reduced. The cavities R11 to R13 can be used to fasten the side cover 21 and other case components (lower case 23, upper cover 33, etc.) with fasteners (rivets, etc.).

  The upper cover 33 is fastened and fixed to the side cover 21 by rivets 52 using the cavity R11. One end of the rivet 52 is located on the upper surface of the upper cover 33, and the other end of the rivet 52 is located in the cavity R11.

  The caulking portion 21c is a plate-like portion integrally formed on the lower surface of the lower portion 21b. The side cover 21 and the second plate 232 are crimped and joined by the crimped portion 21c. FIG. 5 is a view for explaining a method of caulking and joining the side cover 21 and the second plate 232.

  Referring to FIG. 5, the caulking portion 21 c has a flat plate shape before caulking. The caulking portion 21c of the side cover 21 and the first caulking portion 21c of the side cover 21 are plastically deformed by caulking the caulking portion 21c having such a configuration so as to be bent toward the lower surface of the outer edge E1 of the second plate 232 using a tool. The outer edge E1 of the two plates 232 can be crimped and joined.

  The caulking portion (not shown) of the side cover 22 (FIG. 2) and the outer edge E2 (FIG. 4) of the second plate 232 are also caulked and joined in the manner described above. The second plate 232 having high strength (rigidity) is joined to the side covers 21 and 22 so that the entire battery case after joining has high rigidity. As a result, the load can be easily dispersed throughout the battery case, and the durability of the battery case to road surface input is improved. Moreover, the load of the side covers 21 and 22 is reduced by transmitting the load of the side covers 21 and 22 to the second plate 232 of the lower case 23 through the above-mentioned joint portion. Therefore, the side covers 21 and 22 can be reduced in weight and in size.

  Referring again to FIG. 3, the first plate 231 is an end (a side cover shown in FIG. 3) extending to both ends in the width direction (X axis) outside the core member 233 (side covers 21 and 22). Only the end E3 on the 21 side is shown). In this embodiment, these end portions and the side covers 21 and 22 are riveted to each other. For example, as shown in FIG. 3, the end E3 of the first plate 231 is fastened and fixed to the lower portion 21b (side protrusion) of the side cover 21 by the rivet 51 using the cavity R13. One end of the rivet 51 is located on the top surface of the first plate 231, and the other end of the rivet 51 is located in the cavity R13. Further, the adhesive is injected into the gap of the joint portion by the rivet 51 and hardened, so that the joint strength between the end E3 of the first plate 231 and the side projection of the side cover 21 is enhanced.

  Although FIG. 3 shows the cross-sectional structure of the side cover 21, the cross-sectional structure of the side cover 22 (FIG. 2) is basically the same as the cross-sectional structure of the side cover 21 shown in FIG. is there. Also, the bonding mode between the side cover 22 and the lower case 23 is basically the same as the bonding mode between the side cover 21 and the lower case 23 shown in FIG. 3.

  In the inside of the first plate 231, a plurality of flow paths F1 are formed. By providing piping in each of the plurality of gaps formed inside the first plate 231, the flow path F1 can be formed.

  The size, shape, and arrangement of the flow path F1 can be arbitrarily changed in consideration of the strength of the first plate 231, pressure loss, cooling efficiency, and the like. The piping may be made of metal or resin. The material of the pipe can be arbitrarily selected according to the type of fluid (for example, refrigerant) flowing through the flow path F1. Also, if necessary, piping may be omitted. That is, the air gap formed inside the first plate 231 may be used as the flow path F1 as it is.

  The first plate 231 including a plurality of air gaps therein can be formed, for example, by casting. In addition, two plates at least one of which has a recess may be joined to form a first plate 231 including a plurality of voids therein.

  Hereinafter, the example which joins two boards which each has a recessed part, and forms the 1st board 231 which contains several flow path F1 in an inside is demonstrated. FIG. 6 is a view for explaining a method of joining two plates to form the first plate 231. As shown in FIG. FIG. 7 shows the first plate 231 formed in this way.

  Referring to FIG. 6, first, a metal plate 231a having a plurality of recesses R21 (for example, grooves), a metal plate 231b having a plurality of recesses R22 (for example, grooves), and an elliptical cylindrical pipe 231c are prepared. Do. The metal plate 231a and the metal plate 231b each having a recess can be formed, for example, by casting or forging. Alternatively, a flat metal plate may be prepared, and the surface of the metal plate may be scraped by chemical processing (such as etching) or mechanical processing (such as cutting) to form the above-described recesses R21 and R22. The number of recesses R21 and R22 corresponds to the number of channels F1. Further, the shapes of the concave portions R21 and R22 are made to conform to the shape of the pipe 231c.

  Next, the metal plate 231a, the metal plate 231b, and the pipe 231c are combined such that the pipe 231c is sandwiched between the recess R21 of the metal plate 231a and the recess R22 of the metal plate 231b.

  Referring to FIG. 7, by joining metal plate 231a, metal plate 231b, and pipe 231c combined as described above, it is possible to form first plate 231 including a plurality of flow paths F1 inside. A plurality of gaps are formed inside the first plate 231 by the recess R21 and the recess R22, and a pipe 231c is disposed in each of the gaps. A plurality of flow paths F1 are formed in the inside of the first plate 231 by providing the piping 231c in each of the plurality of air gaps formed in the inside of the first plate 231. The metal plate 231a, the metal plate 231b, and the pipe 231c may be joined by any method, such as metallurgical joining (welding, welding, etc.) or joining by an adhesive. Further, the flow path F1 may be formed only by the metal plate 231a and the metal plate 231b by omitting the pipe 231c.

  Referring again to FIG. 3, the first plate 231 and the core member 233 are cooled by causing the refrigerant to flow in each of the plurality of flow paths F1 formed inside the first plate 231, and the first plate 231 and the core It is possible to prevent the material 233 from becoming hot. Further, the battery is also cooled by the refrigerant passing through the position close to the battery (battery modules 10a to 10h). As described above, the flow path F1 (flow path for temperature control) is formed in the battery case (inside of the lower case 23), whereby the temperature control piping outside the battery case can be omitted or simplified.

  The thermal conductivity of the first plate 231 is 50 W / m · K or more, and the thermal conductivity of the core material 233 is 0.1 W in order to enhance the efficiency (cooling efficiency) of the temperature control by the flow path F1. It is particularly preferable to be not more than / m · K. The low heat conductivity core member 233 is disposed below the first plate 231 (in the middle portion of the lower case 23), so that the external heat input is suppressed, and the first plate 231 of high heat conductivity is placed above the lower case 23. The arrangement enables efficient heat transfer near the battery. Further, by disposing the second plate 232 in the lower portion (lower than the core material 233) of the lower case 23, the durability of the battery case against the radiation heat from the road surface and the road surface input is improved.

  As described above, the battery case according to this embodiment has excellent rigidity and heat resistance while being lightweight.

  In the above embodiment, after the sandwich structure of the lower case 23 is completed, the lower case 23 (sandwich panel) is joined to the side covers 21 and 22. However, the present invention is not limited thereto, and the incomplete lower case 23 may be joined to the side covers 21 and 22 before completing the sandwich structure of the lower case 23, and thereafter, the sandwich structure of the lower case 23 may be completed.

  FIG. 8 is a view for explaining a modification of the method of forming the sandwich structure of the lower case 23. Referring to FIG. 8, the first plate 231 and the second plate 232 are joined to the side covers 21 and 22 (only the side cover 21 is shown in FIG. 8). Next, the liquid material 233a of the core material 233 (foam resin) is injected into the space between the first plate 231 and the second plate 232 from the inlet DH provided at the predetermined position of the first plate 231. By filling the space surrounded by the first plate 231, the second plate 232 and the side covers 21 and 22 with the material 233a and foaming and solidifying the material 233a, the core material 233 as shown in FIG. It is formed. When the material 233a solidifies, the first plate 231 and the second plate 232 adhere to the core material 233. The method of foaming the material of the foamed resin is optional, for example, it may be a method of generating air bubbles from a dissolved gas, or may be a method of generating air bubbles by thermal decomposition of the dispersed foaming agent. . The above foaming and solidification may proceed simultaneously.

  In the said embodiment, the joining method of lower case 23 and side covers 21 and 22 can be changed arbitrarily. FIG. 9 is a view for explaining a modification of the method of joining the lower case 23 and the side covers 21 and 22.

  Referring to FIG. 9, in this example, the outer edge E1 of the second plate 232 is fastened and fixed to the lower portion 21b (side protrusion) of the side cover 21 by the rivet 53 using the cavity R13. The bonding strength between the outer edge E1 of the second plate 232 and the side projection of the side cover 21 may be enhanced by injecting an adhesive into the gap of the joint by the rivet 53 and curing. When riveting as shown in FIG. 9 is employed, the caulking portion 21c (FIG. 3) can be omitted. Note that FIG. 9 shows only the manner in which the side cover 21 and the lower case 23 are joined, but the side projection of the side cover 22 (FIG. 2) and the second plate 232 of the lower case 23 both have the form shown in FIG. It may be riveted.

  When the lower case 23 and the side covers 21 and 22 are joined with sufficient strength by joining the second plate 232 of the lower case 23 and the side covers 21 and 22, the first plate 231 of the lower case 23 and the side cover It is not necessary to bond with 21 and 22.

  In the above embodiment, the flow path F1 is formed inside the first plate 231. However, the flow path for temperature control may be formed between the first plate 231 and the core member 233, or may be formed inside the core member 233.

  FIG. 10 is a view showing an example in which the flow path F2 is formed between the first plate 231 and the core material 233. As shown in FIG. Referring to FIG. 10, in this example, a plurality of flow paths F2 are formed at the first core boundary corresponding between the first plate 231 and the core material 233. A flat resin plate is prepared by a known resin molding method, and the surface of the resin plate is scraped by chemical processing (such as etching) or mechanical processing (such as cutting) to form recesses (for example, grooves) on the surface. Core material 233 is obtained. And the flow path F2 is formed by providing the 1st board 231 so that the opening of the crevice of core material 233 may be closed. A pipe (for example, a metal pipe) may be provided between the first plate 231 and the core member 233 (in the recess of the core member 233).

  FIG. 11 is a diagram showing an example in which the flow path F3 is formed inside the core material 233. As shown in FIG. Referring to FIG. 11, in this example, a plurality of flow paths F3 are formed inside core material 233. The core material 233 including the plurality of flow paths F3 inside can be formed by a known resin molding method. By carrying out resin molding of the core material 233 in a state where the piping is fixed at a predetermined position, a piping (for example, a metal piping) may be provided in each flow path F3.

  Two or more of the channels F1 to F3 (see FIGS. 3, 10, and 11) may be employed. For example, the flow path F1 may be formed inside the first plate 231 shown in FIG. 10 or FIG.

  Although the refrigerant is used as the heat medium in the above embodiment, the heat medium is not limited to the medium for cooling, and may be the medium for heating. For example, when the environmental temperature is low, a high temperature heat transfer medium may be flowed through the above-described flow paths (flow paths F1 to F3) to warm the battery and the periphery thereof. Both cooling and heating are possible by using a heat medium with a wide temperature range. The heat medium may be gas or liquid.

  The material of the first plate 231 is optional. For example, copper may be employed as the material of the first plate 231 instead of the aluminum alloy. Further, the first plate 231 may be formed of porous metal in order to reduce the weight of the battery case.

  The material of the second plate 232 can also be arbitrarily changed insofar as it is metal. For example, instead of steel as the material of the second plate 232, aluminum, copper, or an alloy containing at least one of them may be adopted.

  The material of the core material 233 can also be arbitrarily changed in the range which is resin. For example, as the core material 233, a honeycomb structure made of resin may be employed.

  It should be understood that the embodiments disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

  DESCRIPTION OF SYMBOLS 10 battery, 10a-10h battery module, 11 cell, 12 spacer, 13 bus bars, 20 accommodation parts, 21 and 22 side covers, 21a upper part, 21b lower part, 21c caulking part, 23 lower case, 31 front cover, 31a refrigerant introduction port , 32 back cover, 32 a duct, 33 upper cover, 40 reinforcement, 51 to 53 rivets, 100 vehicle, 101 vehicle body, 102 front wheel, 103 rear wheel, 231 first plate, 231 a, 231 b metal plate, 231 c piping, 232 second Plate, 233 core material, 233a material, DH inlet, E1, E2 outer edge, E3 end, F1 to F3 channel, R11 to R13 cavity, R21, R22 recess.

Claims (1)

A battery case including a side wall portion and a bottom portion,
The bottom portion has a sandwich structure in which a first plate and a second plate sandwich a core material,
In the sandwich structure, the first plate is disposed on the battery side,
The core material contains a resin,
The second plate is a metal plate,
The second plate and the side wall portion are joined,
A battery case, wherein a flow path is formed in at least one of the inside of the first plate, the space between the first plate and the core member, and the inside of the core member.

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