Battery pack

Abstract

The utility model provides a battery pack, which is characterized in that the peripheral parts of a conductive shell and a conductive cover are connected with each other, a battery module is accommodated in a space defined in the shell and the cover in a state of being insulated from the shell and the cover, and the shell and the cover are connected through a conductive component to be conducted. The periphery of the housing and the periphery of the cover are sealed by an insulating sealing member over the entire periphery at a position closer to the outer peripheral side than the connection portion of the housing and the cover to the conductive member. Thus, when the case and the cover are short-circuited with the battery module, the case and the cover can be electrically conducted to achieve equipotential, and electrolytic corrosion of the conductive portion of the case and the cover can be suppressed.

Description

Technical Field

[0001] The utility model relates to a battery pack that accommodates a battery module including a plurality of battery cells, and more particularly to a battery pack structure in which a conductive shell and a conductive cover are connected at the peripheral portion and a space for accommodating the battery module is defined inside the conductive shell and the cover. Background Art

[0002] The battery pack for driving an electric vehicle is in a shape in which a battery module is housed in a box, and the battery module includes a battery stack formed by stacking a plurality of battery cells. For example, Patent Document 1 discloses the following structure: a battery module including a plurality of battery cells is housed in a box consisting of an upper shell and a lower shell surrounding the upper and lower sides thereof, respectively. The upper shell and the lower shell are components formed by stacking and arranging a plurality of molding materials in a mold and forming them by heating and pressurizing. The molding material may be a sheet molding compound formed into a sheet by impregnating a resin in glass fiber. The peripheral portions of the upper shell and the lower shell are fastened together by fasteners such as bolts via a sealing component formed by a rubber material or the like. In addition, Patent Document 2 discloses a structure in which conductive pins are vertically inserted between overlapping portions of a plurality of carbon fiber reinforced plastic panels constituting the fuselage of an aircraft to electrically connect the panels.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2022-94716

[0004] Patent Document 2: Japanese Patent Application Publication No. 2019-142479

[0005] As described above, the battery pack is a structure that accommodates a battery module in a box. The battery module includes a battery stack composed of a plurality of battery cells and electrical components such as a busbar attached thereto. More specifically, typically, the box is composed of a component that supports the battery module (hereinafter referred to as a "shell") and a component that covers the battery stack and electrical components (hereinafter referred to as a "cover"), and is fastened in a manner that the edges of the shell and the cover abut against each other. Moreover, the shell and the cover are formed in a state of insulation from the conductive parts of the battery module so that the voltage of the battery is not transmitted even if a person touches them. In this regard, in the case where the battery pack is mounted on a mechanical device such as a vehicle, for the shell installed on the frame of the vehicle body or the mechanical device, it is preferred that the linear expansion coefficient is as equal to that of the vehicle body or the frame as possible, and therefore it is preferred that the shell is formed of the same material as the vehicle body or the frame. Therefore, when the vehicle body or the frame is made of aluminum or other metals, the shell is also made of aluminum or other metals. In this case, the shell has conductivity. In addition, the cover can be formed of any material, but it is preferably a material that is as light as possible, so for example, a member made of carbon fiber reinforced plastic (CFRP) is advantageously used, and in this case, the cover also has conductivity. In this way, when the housing and the cover are formed of conductive materials, in order to prevent the voltage of the battery from being transmitted to the housing and the cover, a structure (insulating structure) is provided on the housing and the cover to electrically insulate the housing and the cover from the battery module by applying an insulating material layer on the inner side thereof.

[0006] In the structure in which the insulating structure is provided on the conductive shell and cover as described above, when the battery pack box is impacted or deformed due to contact between the vehicle or mechanical equipment equipped with the battery pack and other obstacles, if the above-mentioned insulating structure is damaged, the shell or cover and the conductive part of the battery module are short-circuited, and the voltage of the battery can be transmitted to the shell or cover. At this time, if the electrodes of the battery connected by the shell and the cover are the same, no potential difference is generated between the shell and the cover, but when the shell and the cover are short-circuited with different electrodes of the battery, when the shell and the cover are not connected, a potential difference is generated between them, and there is a concern that electric shock may be caused by human contact. Therefore, in the case where the shell and the cover are respectively formed of conductive materials, it is preferred that the shell and the cover are connected to each other so that the shell and the cover are always at the same potential (assuming that when the shell and the cover are connected to different electrodes of the battery, a large current flows between the positive and negative electrodes of the battery at this moment, and the safety mechanism such as the fuse is activated, and the current between the electrodes of the battery is cut off). However, when the housing and the cover are electrically connected, if they are made of different materials, if water or mud adheres to the portion where they are in electrical contact, electrical corrosion occurs, which may cause the appearance of the connection portion between the housing and the cover to deteriorate or become fragile. Utility Model Content

[0007] In view of the above situation, the main technical problem to be solved by the present invention is, in a structure in which the shell and cover of the box body constituting the battery pack are formed of conductive materials and a structure is provided to electrically insulate the box body from the battery module accommodated therein, how to achieve electrical conduction between the shell and the cover to achieve equipotentiality when the shell and the cover are short-circuited with the battery module, and how to suppress electrical corrosion of the conductive parts of the shell and the cover.

[0008] In the utility model, the technical solution to the above-mentioned technical problem is: a battery pack, wherein the peripheral portions of a conductive shell and a conductive cover are connected to each other, and a battery module is accommodated in a space defined inside the shell and the cover in a state insulated from the shell and the cover, and the shell and the cover are connected and conducted via a conductive component, and the peripheral portions of the shell and the cover are sealed to each other by an insulating sealing component over the entire circumference at a position closer to the outer peripheral side than the connection portion where the shell and the cover are connected to the conductive component.

[0009] In the above structure, the "battery pack" refers to a battery pack that is mounted in an electric vehicle or other mechanical equipment for driving or operation, and contains batteries inside a box. As described above, the "housing" and "cover" are parts formed of conductive materials such as metal materials or CFRP materials from the perspective of the requirements, weight or cost of the mechanical equipment mounted. The "battery module" includes electrical components, which include a battery stack that is appropriately constructed by stacking a plurality of battery cells, a wire or bus bar that electrically connects the battery cells and is connected to a terminal for outputting power to the outside of the battery pack, a control device that controls the operation of the battery, and safety mechanisms such as fuses. In addition, the battery module is held on the housing and the cover via an insulating component, so that it is insulated from the housing and the cover in a normal state. In addition, in the present utility model, the conductive component that is connected between the housing and the cover and makes them conductive can be formed of any conductive material (solid). The "insulating sealing component" can be a component formed of any material such as insulating rubber, resin, etc. that can seal between two connected components. In the present invention, it is particularly used in a manner that seals between the shell and the cover over the entire circumference of the peripheral portion of the shell and the cover.

[0010] In the above structure, the shell and cover constituting the box for accommodating the battery module are respectively formed of conductive materials, and the shell and cover are connected and conducted via a conductive member. Therefore, even if the box of the battery pack is impacted and the mechanism for maintaining the insulation between the shell and cover and the battery module is damaged, the shell and cover come into contact with any part of the battery module, and the shell and cover are short-circuited with different electrodes of the battery, the shell and cover are kept at the same potential, so there is no worry of electric shock caused by people touching the shell and cover at the same time.

[0011] In this regard, when the housing and the cover are in a state of conduction through the conductive component, and these components are formed of different materials, if the connection part of the conductive component and its surroundings are exposed to water or mud, etc., electrolytic corrosion may occur. Therefore, in the utility model, as described above, at a position closer to the outer peripheral side than the connection part of the housing and the cover connected to the conductive component, the peripheral part of the housing and the cover is sealed with each other by an insulating sealing component over the entire circumference. Thus, the connection part of the housing and the cover with the conductive component and its surroundings are protected from the influence of water or mud, etc., and the occurrence of electrolytic corrosion as described above can be avoided.

[0012] In the above technical solution, the conductive component may be an elastic body. The conductive component that allows the housing and the cover to be electrically connected may be formed of a flexible elastic material (conductive rubber material, etc.).

[0013] According to this structure, when the cover is mounted on the housing via the conductive component, the conductive component is slightly compressed and in close contact with the surface of the housing and the cover, making it easy to achieve a conductive state between the two. In addition, even if the housing or the cover is deformed by an external force, or a displacement occurs at their connecting portion, the conductive component can be deformed to follow the deformation or displacement, thereby maintaining the conductive state between the housing and the cover.

[0014] In the above structure, the mechanism for keeping the battery module insulated from the housing and the cover may be formed in any manner. In order to avoid direct contact with the conductive portion of the housing, the battery cells or busbars in the battery module may be supported on the housing using a member formed of an insulating material.

[0015] In addition, in the above technical solution, the inner surface of the region of the cover facing the battery module may be covered by an insulating layer, such as a cloth-like member formed of poly(p-phenylene terephthalamide) fiber, to cover the inner surface of the region of the cover facing the battery module, thereby preventing conduction with the battery module as much as possible.

[0016] In the above structure, the peripheral portions of the housing and the cover are in contact with each other via the insulating layer and can be fastened to each other using bolts, etc. From the outside toward the inside of the peripheral portions of the housing and the cover, a fastening portion such as a bolt, a sealing portion using a sealing member, and a conducting portion using a conductive member are sequentially formed.

[0017] Thus, according to the utility model, in a battery pack in which a battery module is housed in a box body composed of a shell and a cover formed of a conductive material, since the shell and the cover are connected by conductive components to become equipotential, even if the voltage of the battery is transmitted to the shell and the cover due to a short circuit with the battery module, electric shock caused by human contact can be prevented. Furthermore, since the contact parts of the shell, the cover and the conductive components are sealed from the outside of the box by the sealing component, moisture or mud cannot reach the contact parts of the conductive components, thereby preventing the occurrence of electrical corrosion near the contact parts of the conductive components, and avoiding the appearance degradation or fragility near the contact parts of the conductive components. The battery pack of the utility model can be used in various electric vehicles or other mechanical devices that use battery power to work.

[0018] Other objects and advantages of the present invention will become apparent from the following description of preferred embodiments of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1A and Figure 1B 2 is a schematic cross-sectional view of the periphery of the case and the cover of the battery pack to which the present embodiment is applied. Figure 1A Indicates a portion where bolts for fastening the housing and the cover are provided. Figure 1B Indicates the part without bolts.

[0020] Figure 2A and Figure 2B : is a schematic cross-sectional view of the periphery of the casing and the cover of a battery pack to which this embodiment is not applied. Figure 2A The case and cover are not conducting. Figure 2B This is the case where the housing and the cover are in electrical communication on the outside. DETAILED DESCRIPTION

[0021] The preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. In the drawings, the same reference numerals represent the same parts.

[0022] First, the basic structure of the battery pack case will be described.

[0023] Reference Figure 1A , Figure 1BIn the battery pack 1 for driving or operating a mechanical device such as an electric vehicle of the present embodiment, an electric module including a battery stack and electric components is fixedly supported by support members 4a and 4b on a housing 4. The battery stack is formed by connecting and stacking battery cells 2 in series or in parallel. The electric components are formed by busbars 3, other wires, a control device (not shown) for controlling the operation of the battery, safety mechanisms (not shown) such as fuses, etc. The busbars 3 are fixed to the battery cells 2 by fixing members 3a, connecting the battery cells 2 to each other and outputting the power from the battery cells 2 to the outside of the battery pack 1. In addition, a cover 5 is fixed relative to the housing 4 in a manner that cooperates with the housing 4 to cover the electric module, whereby the housing 4 and the cover 5 constitute a box for accommodating the electric module.

[0024] In the above-mentioned box structure, when the housing 4 is mounted on the frame (frame) of a machine such as a vehicle, it is preferable that the linear thermal expansion coefficient of the frame is as consistent as possible. Therefore, the housing 4 is typically formed of the same material as the frame of the machine. Therefore, when the frame of the machine is a metal material such as aluminum, it is generally formed of the same metal material. In this case, the housing 4 has conductivity. Therefore, in order not to transmit the voltage of the battery to the housing 4, the support members 4a and 4b supporting the electric module on the housing 4 are formed of an insulating material. On the other hand, the cover 5 arranged on the housing 4 in a manner covering the electric module can be formed of any material, but is formed of a CFRP material for reasons such as light weight and low cost. In this case, the cover 5 also has conductivity. Therefore, in order not to transmit the voltage of the battery to the cover 5, an insulating material layer 6 is applied to the inner wall of the cover 5, especially the wall surface facing the bus bar 3 or other conductive parts of the electric module. In addition, as the insulating material layer 6, for example, a cloth-like member formed of polyparaphenylene terephthalamide fiber can be used. As can be seen from the figure, the cover 5 can be constructed so that its peripheral portion is opposite to the peripheral portion of the housing 4 throughout the circumference, and a fastener such as a bolt 7 is inserted from the cover 5 to the housing 4 at an appropriate interval to fasten. In addition, when the bolt 7 is formed of a conductive material, as shown in the figure, the bolt 7 can be fastened to the cover 5 and the housing 4 via a retainer 7a formed of an insulating material so as not to directly contact the cover 5.

[0025] Next, a countermeasure when a short circuit occurs between the battery module and the case will be described.

[0026] In the above-mentioned battery pack structure, the cover 5 and the shell 4 are properly maintained in an insulated state relative to the battery module. However, when a vehicle or mechanical equipment equipped with the battery pack contacts an obstacle and exerts an impact on the battery pack, the supporting parts 4a and 4b may be damaged, or the insulating material layer 6 may be pierced to displace the battery module, or the cover 5 or the shell 4 may be deformed, so that the conductive part of the battery module contacts the conductive part of the cover 5 or the shell 4, and the battery electrode may be short-circuited with the cover 5 or the shell 4. In this case, Figure 2A As shown in FIG. 1 , when the cover 5 and the housing 4 are insulated from each other and a path S is formed that short-circuits the cover 5 and the housing 4 to different electrodes of the battery, a potential difference ΔV is generated between the cover 5 and the housing 4. When working on the battery pack 1, if the operator touches the cover 5 and the housing 4 at the same time, electric shock may occur. Therefore, in order to always keep the cover 5 and the housing 4 at the same potential, as shown in FIG. Figure 2B As shown in the figure mark X, it is possible to consider making the cover 5 and the shell 4 conductive, but in a case where the conductive part of the cover 5 and the shell 4 is exposed to the outside, if water or mud (figure mark w) reaches there, then when the cover 5 and the shell 4 are formed of different materials, "electrical corrosion" will occur in the conductive part of the cover 5 and the shell 4 and its vicinity, which may cause deterioration of the appearance and fragility of the connection part.

[0027] Therefore, in this embodiment, if Figure 1A , Figure 1B As depicted, a sealing member 9 is applied to connect the cover 5 and the shell 4 on the inner side of their relative peripheral portions via the conductive member 8 so as to be conductive with each other, and to seal between the cover 5 and the shell 4 on the outer side. In addition, the sealing member 9 extends over the entire circumference between the cover 5 and the shell 4 in a manner that cuts off the flow of fluid between the inner side and the outer side. The conductive member 8 may be arranged over the entire circumference between the cover 5 and the shell 4, or may be arranged at appropriate intervals. According to this configuration, the cover 5 and the shell 4 are always maintained at the same potential by the conductive member 8, and water or mud does not reach the contact portion of the conductive member 8 between the cover 5 and the shell 4 and its vicinity, thereby suppressing electrolytic corrosion near the contact portion of the conductive member 8.

[0028] In the configuration of the present embodiment described above, the conductive component 8 is preferably formed of an elastomeric material, which may specifically be an elastomer containing an inorganic filler (a material in which nickel / carbon is added to elastomeric silicon, a material in which conductive fibers are wound around elastomeric polyurethane, etc.), a conductive rubber, etc. According to this configuration, when the peripheral portion of the cover 5 is fastened to the peripheral portion of the shell 4, the conductive component 8 is compressed while being clamped by the peripheral portions of the shell 4 and the cover 5, thereby making the conductive component 8 in close contact with the shell 4 and the cover 5, and the shell 4 and the cover 5 are reliably conductive. In addition, even if the shell 4 or the cover 5 is deformed by an external force or is offset at the peripheral portion, the conductive component 8 can be deformed to follow the deformation or offset to maintain the conductive state between the shell 4 and the cover 5.

[0029] Thus, in the configuration of the present embodiment described above, in the battery pack, equipotentialization can be achieved to ensure the safety of the box body composed of the cover formed of a conductive material such as CFRP and the shell formed of a conductive material such as metal, and to avoid the appearance degradation and fragility of the box body caused by electrical corrosion. The battery pack of the present embodiment is advantageously used for driving or operating the driving device of an electric vehicle or other mechanical equipment.

[0030] The above is an explanation of the implementation mode of the present invention. However, it is easy for those skilled in the art to make many modifications and changes. It is obvious that the present invention is not limited to the above-mentioned exemplary implementation modes, but can be applied to various devices without departing from the concept of the present invention.

Claims

1. A battery pack, characterized in that: The peripheral portions of the conductive shell and the conductive cover are connected to each other, and the battery module is housed in a space defined inside the shell and the cover in a state of being insulated from the shell and the cover. The housing and the cover are connected to each other via a conductive member so as to be in conduction. At a position on the outer peripheral side of a connection portion where the housing and the cover are connected to the conductive member, peripheral edge portions of the housing and the cover are sealed to each other over the entire circumference by an insulating sealing member.

2. The battery pack according to claim 1, characterized in that: The conductive component is an elastomer.

3. The battery pack according to claim 1, characterized in that: An inner surface of a region of the cover opposing the battery module is covered with an insulating layer.

Images