JP2020161211A - Battery module, and vehicle equipped with the same - Google Patents

Abstract

To provide a battery module in which cell reaction force on an end plate caused by expansion of a battery is reduced using a simple structure and the weight of the end plate is reduced.SOLUTION: A battery module includes: a battery stack 2 obtained by stacking a plurality of rectangular battery cells 1 in the thickness direction; a pair of end plates 3 provided to the two end surfaces of the battery stack 2 in the stacking direction; and binder bars which are connected to the pair of end plates 3. The end plates 3 have, on surfaces thereof which face the battery stack 2, recesses 11 which allow expansion of the battery stack 2, and which become deeper towards central portions.SELECTED DRAWING: Figure 2

Description

The present invention relates to a battery module in which end plates arranged at both ends of a battery laminate in which a plurality of square battery cells are laminated are connected by a bind bar, and a vehicle equipped with the same.

A typical battery module includes a battery laminate composed of a plurality of square battery cells, a pair of end plates arranged on both end faces of the battery laminate, and a bind bar connecting the pair of end plates ( See Patent Document 1). In this battery module, by restraining the battery laminate with an end plate and a bind bar, it is possible to assemble the battery laminate composed of a plurality of square battery cells.

International Publication No. 2012/05/7322

In the battery module of Patent Document 1, since a battery laminate composed of a plurality of square battery cells is assembled via a bind bar and an end plate, expansion of the plurality of square battery cells constituting the battery laminate is suppressed. Will be. That is, since the expansion of the square battery cell is suppressed through the bind bar and the end plate, a large force is applied to the bind bar and the end plate.

On the other hand, in a square battery cell, when trying to increase the energy density per volume or the energy density per weight, the dimensional change due to charge / discharge or deterioration tends to be large. Since the load applied to the bind bar and the end plate is caused by the expansion amount of the square battery cell, when a square battery cell having a large dimensional change is used, the end plate and the bind bar are configured in the battery module configuration of Patent Document 1. A large load may be applied and the end plate and bind bar may be deformed or damaged.

The present invention has been developed for the purpose of solving the above drawbacks, and an important object of the present invention is to form an end plate while assembling a plurality of square battery cells via an end plate. An object of the present invention is to provide a technique capable of reducing such a load.

The battery module according to an embodiment of the present invention includes a battery laminate 2 in which a plurality of square battery cells 1 are laminated in the thickness direction, and a pair of end plates arranged on both end surfaces of the battery laminate 2 in the stacking direction. 3 and a bind bar 4 connected to a pair of end plates 3 are provided. The end plate 3 is provided with an expansion allowable recess 11 of the battery laminate 2 that becomes deeper toward the center on the surface facing the battery laminate 2.
A vehicle provided with the battery modules of the above components is also effective as an aspect of the present invention.

In the above battery module, when the square battery cell is charged and discharged, the battery stacking caused by the expansion of the square battery cell is caused by the expansion allowable recess provided on the battery facing surface which is the facing surface of the end plate with the battery stack. Since the expansion of the body can be tolerated, the load applied to the end plate can be reduced. In particular, since the above battery module is provided with an expansion allowable recess that becomes deeper toward the center of the end plate, the outer peripheral edge of the end plate is brought into close contact with the outer peripheral edge of the battery laminate, and the square battery cell is misaligned. Can be held in place so that it does not.

It is a perspective view which shows the battery module which concerns on Embodiment 1 of this invention. It is a schematic horizontal sectional view of the battery module shown in FIG. It is an enlarged horizontal sectional view of the main part of the end plate of the battery module of FIG. It is an enlarged horizontal sectional view of a main part which shows another example of an end plate. It is an enlarged horizontal sectional view of a main part which shows another example of an end plate. It is a block diagram which shows an example which mounts a battery module in a hybrid vehicle which runs by an engine and a motor. It is a block diagram which shows an example which mounts a battery module in an electric vehicle which runs only by a motor.

First, one point of interest of the present invention will be described. In a battery module including a large number of square battery cells, end plates are arranged on both end surfaces of a battery laminate in which a plurality of square battery cells are laminated, and a pair of end plates are connected by a bind bar to form the battery laminate. It is fixed in a state of being pressurized in the stacking direction. In this battery module, both ends of the battery laminate are fixed in a pressurized state with a pair of end plates, so that the end plates are required to have sufficient strength. In the end plate, the square battery cell to be charged and discharged expands and receives the cell reaction force from the inner surface. Since the end plate is pressed from the inner surface by the expanding battery laminate, it receives a cell reaction force proportional to the product of the area of the battery laminate and the pressure pressed by the battery laminate. Therefore, in a square battery cell whose dimensional change is large due to charging / discharging or the like, a cell reaction force having a size corresponding to the amount of expansion acts on the end plate. Therefore, when trying to suppress the expansion of the square battery cell to the extent that the dimensions do not change substantially, the cell reaction force acting on the end plate is, for example, a number in the battery module for the power source that drives the traveling motor of the vehicle. It becomes extremely large with tons.

One of the purposes of the configuration in which the pair of end plates are connected by a bind bar and the battery laminate is fixed in a state of being pressurized in the stacking direction is to suppress dimensional variation of the battery module. Specifically, the dimensional variation of the battery module suppresses the dimensional variation of the battery module because it may cause a problem that the battery module cannot be arranged in a specified space when the battery module is mounted on a vehicle or the like. In order to do so, a battery laminate composed of a plurality of battery cells is assembled.
Therefore, if it is possible to suppress the dimensional variation of the battery module while allowing the expansion of the square battery cell, it is possible to reduce the load on the end plate while maintaining the performance as the battery module.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the embodiments shown below are examples for embodying the technical idea of the present invention, and the present invention is not specified as the following. Further, the present specification does not specify the members shown in the claims as the members of the embodiment. Unless otherwise specified, the dimensions, materials, shapes, relative arrangements, etc. of the constituent members described in the embodiments are not intended to limit the scope of the present invention to that alone, but merely explanatory examples. It's just that. The size and positional relationship of the members shown in each drawing may be exaggerated to clarify the explanation. Further, in the following description, members of the same or the same quality are shown with the same name and reference numeral, and detailed description thereof will be omitted as appropriate. Further, each element constituting the present invention may be configured such that a plurality of elements are composed of the same member and the plurality of elements are combined with one member, or conversely, the function of one member is performed by the plurality of members. It can also be shared and realized. In addition, the contents described in some examples and embodiments can be used in other embodiments and embodiments. Furthermore, in the specification, the vertical direction shall be specified in the drawings.

(Embodiment 1)
1 and 2 show the battery module 10 according to the first embodiment. FIG. 1 shows a perspective view of the battery module, and FIG. 2 shows a schematic horizontal sectional view of the battery module. The battery module 10 shown in these figures is a battery laminate 2 in which a plurality of square battery cells 1 are laminated with an insulating material separator 6 interposed therebetween, and both ends of the battery laminate 2 are located on both end surfaces of the battery laminate 2. A pair of end plates 3 sandwiched from a surface and held in place, a bind bar 4 connecting the pair of end plates 3, and a bolt 5A of a fixing pin 5 for fixing the bind bar to the end plate 3 I have.

As shown in FIG. 1, the above battery module 10 has an elongated box shape as a whole, and a large number of square battery cells 1 are laminated to form a battery laminate 2, and the battery laminate 2 is formed from both end faces in the stacking direction to end plates 3 The end plates 3 at both ends are connected by a bind bar 4 to fix the battery laminate 2 in a pressurized state. In the battery laminate 2, the stacked square battery cells 1 are connected in series, in parallel, or in parallel with a series via a bus bar (not shown) of a metal plate.

In the square battery cell 1, the opening of the outer can having a square shape whose outer shape is thinner than the width is closed with a sealing plate, positive and negative electrode terminals are provided on the sealing plate, and a bus bar is connected to the electrode terminals. are doing. A battery module in which the square battery cells 1 are connected in series with each other can increase the output voltage to increase the output, and a battery module in which the square battery cells 1 are connected in parallel can increase the current capacity. The square battery cell 1 is a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery. However, the square battery cell can be any secondary battery currently used or will be developed, such as a nickel metal hydride battery or a nickel cadmium battery.

The pair of end plates 3 arranged at both ends of the battery laminate 2 are connected to the bind bar 4, hold the battery laminate 2 in a pressurized state, and receive a cell reaction force due to the expansion of the square battery cell 1. The end plate 3 shown in FIG. 2 is provided with an expansion allowable recess 11 on the battery facing surface 3A, which is the facing surface with the battery laminate 2, in order to reduce the cell reaction force. The square battery cell 1 is charged and discharged and expands, but the amount of expansion increases in the central portion. Since the battery laminate 2 is made by stacking a plurality of square battery cells 1, when the central portion of the square battery cell 1 expands, the battery laminate 2 in which the central portion of the square battery cell 1 is laminated has a large expansion of the central portion at the end surface. .. In order to allow the expansion of the square battery cell 1, the end plate 3 is provided with an expansion allowable recess 11 having a central portion as a recess on the surface facing the battery stack 2. The end plate 3 can be provided with an expansion allowable recess 11 to significantly reduce the cell reaction force. This is because the pressure at which the end surface of the battery laminate 2 presses against the inner surface of the end plate 3 is significantly reduced by allowing the expansion.

The depth of the expansion allowable recess 11 is set to an optimum value in consideration of the dimensions of the battery laminate 2 in the stacking direction. The end plate 3 can reduce the cell reaction force by deepening the expansion allowable recess 11. Therefore, for example, the depth (d) of the expansion allowable recess 11 is set to 1/3000 or more, preferably 1/2000 or more, and more preferably 1/1000 or more of the thickness of the battery laminate 2 in the stacking direction. If the expansion allowable recess 11 is too deep, the amount of deformation of the square battery cell 1 becomes large. Therefore, the depth (d) of the expansion allowable recess 11 is set to an optimum value in consideration of the amount of deformation of the square battery cell 1, and therefore, for example, 1/100 or less, preferably 1/200 or less, more preferably 1. It shall be / 300 or less. However, the present invention does not specify the depth (d) of the expansion allowable recess 11 in the above range, and the depth (d) of the expansion allowable recess 11 is determined by the expansion amount of the square battery cell 1 and the expansion amount of the end plate 3. It is set to the optimum value in consideration of the strength.

FIG. 3 shows an enlarged cross-sectional view of the battery facing surface 3A of the end plate 3. The end plate 3 in this figure is provided with a flat surface portion 12 having a predetermined width along the outer peripheral edge. The flat surface portion 12 provided on the outer peripheral edge of the end plate 3 can contact the outer peripheral edge of the square battery cell 1 in a surface contact state with a predetermined width, and can more reliably prevent the misalignment of the square battery cell 1. Further, in the end plate 3 shown in the enlarged cross-sectional view of FIG. 4, the shape of the boundary portion 13 between the flat surface portion 12 and the expansion allowable recess 11 is gradually lowered toward the central portion of the expansion allowable recess 11 (α). ) Is enlarged. The end plate 3 of FIG. 3 has a protruding line 14 that linearly protrudes toward the battery laminate 2 at the boundary line between the flat surface portion 12 and the expansion allowable recess 11. The end plate 3 in which the projecting line 14 projects toward the battery stack 2 may damage the surface of the square battery cell 1 when the projecting line 14 locally presses the end surface of the battery stack 2 linearly. In the end plate 3 shown in the enlarged cross-sectional views of FIGS. 4 and 5, in order to prevent this adverse effect, the shape of the boundary portion 13 between the flat surface portion 12 and the expansion allowable recess 11 is inclined downward toward the central portion. The tilt angle (α) is increased. The end plate 3 of FIG. 4 changes the inclination angle (α) of the downward slope stepwise, and the end plate 3 of FIG. 5 continuously changes the inclination angle (α) so that the boundary portion 13 is a curved surface. ..

The end plate 3 of FIG. 4 divides the protruding lines 14 formed at the boundary portion 13 into a plurality of rows to prevent damage to the battery laminate 2. This is because the tip angle of the protruding line 14 can be brought closer to a flat surface by dividing the protruding line 14 into a plurality of rows. The end plate 3 of FIG. 5 has a boundary portion 13 as a curved surface and has no protruding line to prevent damage to the battery laminate 2. Further, the battery module 10 having this structure is characterized in that an elastic heat conductive sheet 7 described later is arranged between the battery laminate 2 and the end plate 3 to prevent damage to the elastic heat conductive sheet 7. This is because the protruding line 14 locally presses the elastic heat conductive sheet 7 and does not damage it.

In the battery module 10 shown in the cross-sectional view of FIG. 2, an elastic heat conductive sheet 7 is arranged between the battery facing surface 3A and the battery laminate 2. The elastic heat conductive sheet 7 is a sheet that is elastically deformed in the thickness direction by being pushed by the cell reaction force generated by the expansion of the battery laminate 2. The elastic heat conductive sheet 7 is pressed by the cell reaction force and deforms thinly. In the elastic heat conductive sheet 7, for example, a heat conductive powder such as metal or graphite or a heat conductive fiber such as metal fiber is added to a sheet-shaped heat conductive gel, a flexible rubber elastic body or an open cell plastic foam. All sheets that are compressed and thinly elastically deformed can be used.

One surface of the elastic heat conductive sheet 7 is in close contact with the end plate 3 in a surface contact state, and the other surface is in contact with the end surface of the battery laminate 2. The elastic heat conductive sheet 7 in which both sides are in close contact with the end face of the battery laminate 2 and the end plate 3 conducts heat energy of the battery laminate 2 that generates heat to the end plate 3. The battery module 10 capable of thermally conducting the heat generated by the battery laminate 2 to the end plate 3 via the elastic heat conduction sheet 7 reduces the temperature rise of the square battery cell 1 arranged on the end face of the battery laminate 2 and causes thermal runaway. Can be prevented. The elastic heat conductive sheet 7 in which both sides of the battery laminate 2 are in close contact with the battery laminate 2 and the end plate 3 in both the expanded state and the non-expanded state and the thermal runaway occurs always generate heat of the battery laminate 2 at the end plate. Efficiently conducts heat to 3.

As the elastic heat conductive sheet 7, an insulating sheet is preferably used. The insulating elastic heat conductive sheet 7 can be realized by laminating an insulating sheet on the heat conductive sheet. The insulating elastic heat conductive sheet 7 in which the heat conductive sheet and the insulating sheet are laminated is a sheet that elastically deforms either or one of the heat conductive sheet and the insulating sheet. The elastic heat conductive sheet 7 in which a heat conductive sheet and an insulating sheet are laminated is obtained by laminating a heat conductive sheet having excellent heat conductive characteristics and a sheet having excellent insulating characteristics to have excellent heat conductive characteristics and insulating characteristics. Can be realized.

In the battery module 10 in which the insulating elastic heat conductive sheet 7 is arranged between the battery laminate 2 and the end plate 3, the battery facing surface 3A of the end plate 3 can be made of metal. In the battery module 10, the surface facing the battery laminate 2 may be a metal plate, or the entire end plate 3 may be made of a metal such as aluminum. Further, the battery laminate 2 in which the square battery cells 1 whose surface is insulated by an insulating sheet is laminated does not use the elastic heat conductive sheet 7 as an insulating sheet, and is insulated from the conductive elastic heat conductive sheet 7. The outer can of the square battery cell 1 and the end plate 3 can be insulated without stacking the sheets.

In the battery module 10 of FIGS. 1 and 2, the entire end plate 3 is made of a metal block made of aluminum. The battery module 10 can be made of aluminum in which the end plate 3 is molded by a mold by reducing the cell reaction force at the expansion allowable recess 11 of the end plate 3. Although not shown, the end plate 3 can be an end plate 3 in which the surface facing the battery laminate 2 is a metal plate of iron or an iron alloy. The end plate 3 having a metal plate facing the battery laminate 2 has a structure in which a plurality of metal plates are laminated, a structure in which a metal rod or a metal pipe is fixed to the surface of the metal plate, or plastic on the metal plate. The structure may be such that the molded bodies are laminated.

Both ends of the bind bar 4 are connected to the end plate 3 to fasten the battery laminate 2 in a pressurized state. The bind bar 4 of FIG. 1 is fixed by screwing both ends of the metal plate to both side surfaces of the end plate 3 with bolts 5A which are fixing pins 5. Although not shown, the bind bar can also be fixed by bending both ends of the metal plate inward to provide a bent piece and screwing the bent piece to the surface of the end plate.

(Vehicles equipped with battery modules)
The above battery module is most suitable as a power source for supplying electric power to a motor for traveling an electric vehicle. As a vehicle equipped with a battery module, a hybrid vehicle or a plug-in hybrid vehicle that runs on both an engine and a motor, an electric vehicle that runs only on a motor, and the like can be used, and is used as a power source for these vehicles. An example in which a large number of the above-mentioned battery modules are connected in series or in parallel to obtain electric power for driving a vehicle, and a large-capacity, high-output power supply device 100 to which a necessary control circuit is added is constructed and mounted. Is shown.

FIG. 6 shows an example in which a power supply device is mounted on a hybrid vehicle that runs on both an engine and a motor. The vehicle HV equipped with the power supply device shown in this figure includes a vehicle body 90, an engine 96 for traveling the vehicle body 90, a motor 93 for traveling, and wheels driven by these engines 96 and a motor 93 for traveling. 97, a power supply device 100 for supplying electric power to the motor 93, and a generator 94 for charging the battery of the power supply device 100 are provided. The power supply device 100 is connected to the motor 93 and the generator 94 via the DC / AC inverter 95. The vehicle HV runs on both the motor 93 and the engine 96 while charging and discharging the battery of the power supply device 100. The motor 93 is driven to drive the vehicle in a region where the engine efficiency is low, for example, when accelerating or traveling at a low speed. The motor 93 is driven by being supplied with electric power from the power supply device 100. The generator 94 is driven by the engine 96 or by regenerative braking when braking the vehicle to charge the battery of the power supply device 100.

Further, FIG. 7 shows an example in which a power supply device is mounted on an electric vehicle traveling only by a motor. The vehicle EV equipped with the power supply device shown in this figure supplies electric power to the vehicle main body 90, the traveling motor 93 for running the vehicle main body 90, the wheels 97 driven by the motor 93, and the motor 93. A power supply device 100 for charging and a generator 94 for charging the battery of the power supply device 100 are provided. The power supply device 100 is connected to the motor 93 and the generator 94 via the DC / AC inverter 95. The motor 93 is driven by being supplied with electric power from the power supply device 100. The generator 94 is driven by the energy used for regenerative braking of the vehicle EV to charge the battery of the power supply device 100.

The embodiment may be specified by the following configuration.
According to the battery module according to one aspect of the present invention, a plurality of square battery cells 1 are laminated in the thickness direction and arranged on both end surfaces of the battery laminate 2 in the stacking direction. A pair of end plates 3 and a bind bar 4 connected to the pair of end plates 3 are provided, and the end plate 3 is a battery laminate 2 that becomes deeper toward the center on a surface facing the battery laminate 2. The expansion allowable recess 11 can be provided.

The above battery module has a feature that the square battery cell expands and the cell reaction force that presses the end plate from the inner surface can be reduced while having an extremely simple structure. This is because the above battery module is provided with an expansion allowable recess that allows expansion of the battery laminate due to expansion of the square battery cell on the battery facing surface that is the facing surface of the end plate with the battery stack. This is because it allows the expansion of the battery. In particular, since the above battery module is provided with an expansion allowable recess that becomes deeper toward the center of the end plate, the outer peripheral edge of the end plate is brought into close contact with the outer peripheral edge of the battery laminate, and the square battery cell is misaligned. Can be held in place so that it does not.
Therefore, the above battery modules allow expansion of the central portion of the battery laminate while holding a plurality of square battery cells stacked on each other at the outer peripheral edge to prevent misalignment. Since the square battery cell has a large expansion in the central portion, the structure that holds the outer peripheral edge without displacement and allows the expansion of the central portion in the expansion allowable recess prevents the displacement of the square battery cell and causes expansion. The cell reaction force can be reduced by allowing it.

The above features are extremely important for a battery module that is charged and discharged with a large current, such as a battery module that drives a traveling motor of a vehicle. This is because the high-current battery module has a thick metal plate bus bar fixed to the electrode terminals of adjacent square battery cells arranged adjacent to each other and connected in series or in parallel. A square battery cell in which a bus bar of a thick metal plate is fixed to an electrode terminal has a drawback that if the position is relatively displaced, an unreasonable stress acts on the connecting portion between the bus bar and the electrode terminal to damage the cell. This is because the bus bar of the thick metal plate is deformed and cannot absorb the relative misalignment of the square battery cell. Since the above battery module allows expansion and reduces cell reaction force while preventing misalignment of the square battery cell, a thick metal plate can be used for the busbar to reduce the electrical resistance of the busbar and a large current. It also realizes the feature that the power loss of the bus bar during charging and discharging can be reduced and the power efficiency of the entire battery module can be increased.

Furthermore, since the above battery module can reduce the cell reaction force of the end plate, the end plate is not required to have a tough structure that can withstand a strong cell reaction force, and the amount of deformation due to the cell reaction force while reducing the weight of the end plate. The feature that the square battery cell can be arranged in a fixed position is also realized.

Further, in the battery module, an elastic heat conductive sheet 7 that elastically deforms in the thickness direction due to the cell reaction force of the battery laminate 2 is arranged between the battery facing surface 3A of the end plate 3 and the battery laminate 2. One surface of the elastic heat conductive sheet 7 can be brought into contact with the end plate 3 in a surface contact state, and the other surface can be brought into contact with the end surface of the battery laminate 2. Further, in the battery module, the elastic heat conductive sheet 7 can be used as an insulating sheet.

Further, the battery module may be provided with a flat surface portion 12 having a predetermined width along the outer peripheral edge of the battery facing surface 3A of the end plate 3, and an expansion allowable recess 11 may be provided inside the flat surface portion 12.

Furthermore, in the battery module, the inclination angle (α) of the downward slope of the boundary portion between the flat surface portion 12 and the expansion allowable recess 11 provided in the end plate 3 is gradually increased toward the central portion of the expansion allowable recess 11. be able to.

Furthermore, in the battery module, the boundary portion between the flat surface portion 12 of the end plate 3 and the expansion allowable recess 11 can be a curved surface whose inclination angle continuously changes.

According to the vehicle equipped with the battery module according to one aspect of the present invention, the battery module 10 having any of the above configurations, the traveling motor 93 to which power is supplied from the battery module 10, the battery module 10 and the motor A vehicle body 90 on which the 93 is mounted and wheels 97 driven by a motor 93 to drive the vehicle body 90 can be provided.

The battery module according to the present invention and a vehicle equipped with the battery module can be suitably used as a power supply device for a hybrid car, a plug-in hybrid car, an electric vehicle, or the like.

1 ... Square battery cell 2 ... Battery laminate 3 ... End plate 3A ... Battery facing surface 4 ... Bind bar 5 ... Fixing pin 5A ... Bolt 6 ... Separator 7 ... Elastic heat conductive sheet 10 ... Battery module 11 ... Expansion allowable recess 12 ... Flat surface 13 ... Boundary 14 ... Protruding line 90 ... Vehicle body 93 ... Motor 94 ... Generator 95 ... DC / AC inverter 96 ... Engine 97 ... Wheels 100 ... Power supply HV ... Vehicle EV ... Vehicle

Claims (7)

A battery laminate made by stacking multiple square battery cells in the thickness direction,
A pair of end plates arranged on both end faces in the stacking direction of the battery laminate,
With a bind bar connected to the pair of end plates
The battery module is characterized in that the end plate is provided with an expansion allowable recess of the battery laminate that becomes deeper toward the center on a surface facing the battery laminate. The battery module according to claim 1.
An elastic heat conductive sheet that elastically deforms in the thickness direction due to the cell reaction force of the battery laminated body is arranged between the battery facing surface of the end plate and the battery laminated body, and one of the elastic heat conductive sheets. A battery module characterized in that a surface is in contact with an end plate in a surface contact state, and the other surface is in contact with an end surface of a battery laminate. The battery module according to claim 2.
A battery module characterized in that the elastic heat conductive sheet is an insulating sheet. The battery module according to any one of claims 1 to 3.
A battery module characterized in that a battery facing surface of the end plate has a flat surface portion having a predetermined width along an outer peripheral edge, and the expansion allowable recess is provided inside the flat surface portion. The battery module according to claim 4.
At the boundary portion between the flat surface portion and the expansion allowable recess provided on the end plate, the inclination angle (α) of the downward slope is gradually increased toward the central portion of the expansion allowable recess. Battery module. The battery module according to claim 5.
A battery module characterized in that the end plate serves as a curved surface whose inclination angle continuously changes at a boundary portion between the flat surface portion and the expansion allowable recess. A vehicle equipped with the battery module according to any one of claims 1 to 6.
The battery module, a traveling motor to which power is supplied from the battery module, a vehicle body on which the battery module and the motor are mounted, and wheels driven by the motor to drive the vehicle body are provided. vehicle.

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