JP2005116278A - Laminated battery, protection member and battery unit for the laminated battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the leakage of an electrolytic solution caused by damage to a heat-fused part of a laminate sheet. <P>SOLUTION: In each of the heat-fused parts 1c which becomes the longitudinal direction of a laminated battery 1, a protection member 10 is rolled in by the heat-fused part 1c, and the protection member 10 is fixed so that the end 10b is extended from the heat-fused part 1c. The protection member 10 is composed of a cross-sectionally circular rod member, its length L1 is not less than the length L2 of the heat-fused part 1c of the laminate sheet 7, and shorter than the distance L3 between bulkheads 21 of a battery housing case 20. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a laminate type battery covered with a laminate sheet, a protective member for the laminate type battery, and a battery unit.

  Conventionally, batteries used in portable information communication devices such as mobile phones and notebook computers and small electronic devices such as video cameras and card calculators that emphasize portability are increasingly lighter and thinner. It has been demanded. In addition, demands for resource conservation and energy conservation for the protection of the global environment are increasing, and electric vehicles and hybrid electric vehicles (hereinafter simply referred to as “electric vehicles, etc.”) equipped with secondary batteries for motor drive. (Also known as) is being developed rapidly. Naturally, secondary batteries mounted on electric vehicles and the like are also required to be lightweight and thin in order to improve steering characteristics and cruising distance.

  In order to make the battery lighter and thinner in response to such a request, a laminate sheet in which a metal layer such as aluminum and a heat-weldable resin layer are laminated on an outer package via an adhesive layer to form a thin sheet is provided. The battery used has been developed. Laminate sheets generally have a structure in which both surfaces of a thin metal layer such as aluminum are covered with a thin resin layer, are resistant to acids and alkalis, and are lightweight and flexible.

  FIG. 9 shows a schematic external perspective view of an example of a conventional laminated battery.

  The laminate type battery 200 has a structure in which a power generation element composed of a positive electrode side active electrode and a negative electrode side active electrode laminated via a separator (not shown) is sealed with a laminate sheet 207. The laminate sheet 207 has four sides heat-sealed, and a positive electrode terminal 203 connected to the positive electrode side active electrode extends from the heat-sealed portion 201a in the short direction of the laminate-type battery 1. Further, a negative electrode terminal 204 connected to the negative electrode side active electrode extends from the heat fusion part 201b on the side facing the heat fusion part 201a.

  When a laminated battery having such a structure is mounted on an electric vehicle or the like, an electrode terminal is connected in series in order to obtain a required voltage from a rated voltage of a unit cell, or a required current capacity is obtained. The electrode terminals are connected in parallel to form a battery pack, housed in a case, and mounted on an electric vehicle. This is because a laminate type battery is prone to deformation of the laminate sheet itself, so it is not only easier to handle it as a battery pack, but it is also easier to handle the battery by introducing cooling air into the case. This is because the wall surface of the case can be used as a cooling air flow path when cooling, and cooling air can be efficiently supplied to a plurality of batteries housed in the case. For this reason, various proposals for fixing the laminated battery in the case have been made (for example, see Patent Document 1).

  On the other hand, as a result of diligent research, the inventors focused on the difference in heat capacity between the battery body and the electrode terminal with respect to cooling the battery, and individually cooled the electrode terminal and the battery body having a larger heat capacity than the electrode terminal. It has been found that a configuration in which a laminated battery is accommodated in a case that can be used is suitable.

  FIG. 10A shows an example of the structure of a battery storage case that can individually cool the electrode terminal and the battery body.

  The battery storage case 320 has a structure including two partition walls 321 provided substantially in parallel between the two side walls 322 and having an opening 321a. In the laminate type battery 200, the main body 202 is disposed in a main body storage portion 324 between opposing partition walls 321, and the positive electrode terminal 203 and the negative electrode terminal 204 are stored so as to extend to the electrode cooling path 323 side. ing. In the electrode cooling path 323, cooling air for cooling the positive electrode terminal 203 and the negative electrode terminal 204 is supplied in the direction of arrow a from a cooling air supply unit (not shown). Cooling air for cooling the main body 202 of the laminated battery 200 is also supplied from the cooling air supply unit to the main body storage unit 324.

The opening 321a formed in the partition wall 321 is the amount of cooling air flowing through the electrode cooling path 323 to the main body storage unit 324 side, or conversely, the cooling air flowing through the main body storage unit 324 toward the main body storage unit 324 side. In order to limit the outflow amount, the width of the laminate type battery 200 is narrower than the width in the short direction and slightly wider than the widths of the positive electrode terminal 203 and the negative electrode terminal 204.
International Publication No. 00/59063 Pamphlet

  In the case of the structure shown in FIG. 10A, although the cooling efficiency of the laminated battery 200 is improved, when the battery storage case 320 is vibrated, the end portions 207a of the four corners of the laminate sheet 207 collide with the partition wall 321. There was a case where it was damaged.

  That is, as shown in FIG. 10A, when the laminate-type battery 200 mounted with a gap between the partition walls 321 moves in the direction of arrow b in FIG. There was a phenomenon in which the end portion 207b of the sheet 207 collided with the partition 321 on the left side in the figure and the end portion 207b was crushed. Subsequently, as shown in FIG. 10C, when the laminated battery 200 moves in the direction of the arrow c in the opposite direction, this time, the end 207a collides with the partition 321 on the right side in the figure, and the end 207a is crushed. It will be. When the vibration further continues, as shown in FIG. 10D, the laminate type battery 200 moves again in the direction of the arrow b, collides with the partition 321 on the left side in the figure, and the end 207b is further crushed. In this way, every time the end portions 207a and 207b collide with the partition 321 and are crushed, the amount of movement of the laminate-type battery 200 increases, and the amount of energy when colliding with the partition 321 also increases. The crushing of the end portions 207a and 207b of 207 progressed at an accelerated rate, and finally a crack 207c (see FIG. 10D) was generated in the laminate sheet 207, and the internal electrolyte solution might leak.

  Accordingly, the present invention provides a laminate type battery capable of preventing damage to the laminate sheet of the laminate type battery housed in the case, and leakage of the electrolyte due to the damage, a protective member for the laminate type battery, and An object is to provide a battery unit.

  In order to achieve the above object, a laminate type battery of the present invention includes an electrode terminal that is electrically connected to a power generation element including an electrolyte and is disposed to face each other, and is made of a laminate sheet and encloses the power generation element. In the laminate type battery, the exterior body has a first side extending from the electrode terminal and a second side extending in the arrangement direction of the electrode terminals. The length of the second side is the second side. It has at least one protective member longer than the length in the arrangement direction, and both end surfaces of the protection member are fixed to the second side so as to extend from both ends in the arrangement direction of the second side. It is characterized by.

  In the laminate type battery according to the present invention, the protective member may be a rod-shaped member, and may be wound around and fixed to the second side, or a long groove may be formed in the protective member. The protective member may be fixed to the second side by inserting the second side into the long groove.

  The protective member for a laminate type battery of the present invention has an electrode terminal that is electrically connected to a power generation element containing an electrolyte and is disposed to face each other, and is made of a laminate sheet and encloses the power generation element The body is a protective member for a laminated battery having a first side extending from the electrode terminal and a second side extending in the arrangement direction of each electrode terminal, and a buffer member is provided on both end faces. And having a length longer than the length of the second side in the arrangement direction.

  Further, the protective member for a laminate type battery of the present invention encloses the power generation element, which is made of a laminate sheet, having electrode terminals that are electrically connected to the power generation element including the electrolytic solution and arranged to face each other. The exterior body is a protective member for a laminate type battery having a first side from which the electrode terminals extend and a second side extending in the arrangement direction of the electrode terminals, A long groove that is longer than a length of the second side in the arrangement direction and into which the second side is inserted is formed.

  Moreover, the protective member for a laminate type battery of the present invention may have a buffer member on both end faces.

  The battery unit of the present invention is a battery unit in which at least one laminate-type battery is accommodated between wall surfaces arranged opposite to each other, and an opening for extending an electrode terminal of the laminate-type battery is formed on the wall surface. The laminated battery of the present invention is housed between the wall surfaces.

  Moreover, the battery unit of this invention may be provided with the buffer member in the site | part corresponding to the both end surfaces of a protection member of a wall surface.

  According to the present invention, both end surfaces of the protective member are fixed to the second side so as to extend from both ends in the arrangement direction of the second side of the laminate sheet, thereby acting in the longitudinal direction of the protective member. Since the external force is applied to both end surfaces of the protective member and is not directly applied to the laminate sheet, the laminate sheet can be prevented from being deformed or crushed. Thereby, it is possible to prevent damage to the laminate sheet and leakage of the electrolyte solution due to the damage.

Next, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 is a schematic external perspective view of the laminate type battery of the present embodiment, FIG. 2 is a schematic view showing a method for forming an exterior body using a laminate sheet, and FIG. 3 is viewed from the direction of arrow A shown in FIG. The partially enlarged view of the part to which the protection member of the laminate type battery of this embodiment was attached is shown, respectively. FIG. 4A shows a schematic plan view of a battery unit in which the laminate type battery shown in FIG. 1 is stored in a battery storage case, FIG. 4B shows an arrow C shown in FIG. -Cross-sectional views in the C direction are shown.

  A laminate type battery 1 is a laminate in which a power generation element (not shown) having a positive electrode side active electrode, a negative electrode side active electrode, and an electrolyte is formed by superposing a metal film such as aluminum and a heat-fusible resin film. The sheet 7 has a structure in which the sheet 7 is heat-sealed and sealed at the four sides of the heat-sealing portions 1a, 1b, and 1c.

  The power generation element of the laminate type battery 1 may be a laminated type composed of a positive electrode side active electrode and a negative electrode side active electrode laminated via a separator, or a strip-like positive electrode side active electrode and a negative electrode side active electrode. After winding this through a separator, it may be a wound type having a structure in which the positive electrode side active electrode and the negative electrode side active electrode are stacked in an intersecting manner by compressing in a flat shape.

  The positive electrode terminal 3 connected to the positive electrode side active electrode extends from the heat fusion part 1a in the short direction of the laminate type battery 1, and the positive electrode terminal 3 extends from the heat. A negative electrode terminal 4 connected to the negative electrode side active electrode extends from the heat fusion part 1b on the side facing the fusion part 1a. Aluminum is often used as the positive electrode terminal 3 and copper or nickel is frequently used as the negative electrode terminal 4 due to its electrical characteristics.

  The sealing of the power generation element by the laminate sheet 7 first sandwiches the power generation element between the two laminate sheets 7 as shown in FIG. 2 (a), and the positive electrode terminal 3 extends from the heat-sealing portion 1a side. The negative electrode terminal 4 is set in a state of extending from the heat fusion portion 1b side, and thereafter, the four sides of the heat fusion portions 1a, 1b, and 1c are thermally fused.

  Note that the method of forming the exterior body of the laminate sheet 7 is not limited to this, and as shown in FIG. 2B, one laminate sheet 7 is bent at the bending portion 7a and the remaining three sides are heat-sealed. It may be formed. Or as shown in FIG.2 (c), after laminating | stacking one laminate sheet 7 and heat-sealing with the center seal | sticker part 7b, you may form by heat-sealing the remaining 2 sides. . 2A to 2C indicate the region where the laminate sheet 7 is heat-sealed.

  Each heat-sealing of the laminated battery 1 formed with the laminate sheet 7 as an exterior body extends in the arrangement direction of the positive electrode terminal 3 and the negative electrode terminal 4, that is, extends in the longitudinal direction of the laminated battery 1. A total of two protective members 10 are attached to each part 1c. Each of the protection members 10 is for preventing the heat fusion part 1c from being deformed when an external force is applied to the heat fusion part 1c. The length L1 is equal to or longer than the length L2 of the heat-sealing part 1c of the laminate sheet 7, and is shorter than the distance L3 between the partition walls 21 of the battery storage case 20 described later (see FIG. 4). The protective member 10 is disposed on the heat-sealed portion 1c so that the respective end portions 10b on both sides extend from the heat-fused portion end 1c ″ of the heat-fused portion 1c, and after applying an adhesive, It is being fixed with respect to the heat-fusion part 1c by winding by the fusion | fusion part 1c.

  In addition, when the exterior body by the laminate sheet 7 is formed by the forming method shown in FIG. 2B or FIG. 2C, the protective member 10 has the heat fusion part 1c having the configuration shown in FIG. Will be attached to the side 11 corresponding to.

  Further, the shape and fixing method of the protective member 10 are not limited to this, and the protective member 10 slides in the axial direction due to vibration, and the relative positional relationship between the protective member 10 and the heat fusion part 1c is deviated. As long as the heat fusion part 1c does not collide with the partition wall 21, it may be anything. For example, by making the radius of the fixed portion 10a that is wound and fixed at the heat fusion portion 1c smaller than the end portion 10b that extends from the heat fusion portion 1c, the heat fusion portion 1c becomes the axis of the protective member 10. The cross-sectional shape of the protective member 10 may be a rectangle, a triangle, an ellipse, or the like, or a hollow pipe shape. Also good. In addition, the method of fixing the protective member 10 to the heat-sealing portion 1c is, for example, fixing by sandwiching the heat-sealing portion 1c of the laminate sheet 7 between the laminate sheets 7 when heat-sealing. Alternatively, it may be simply bonded and fixed on the heat-sealing portion 1c.

  The material of the protective member 10 is also not particularly limited, but is a metal having a strength that does not break even if it vibrates with the stroke amount L3-L1 of the laminate type battery 1 between the partition walls 21 and collides with the partition wall 21. The resin is preferably lightweight and has insulating properties, such as wood. In the present embodiment, the protective member 10 is shown as an example having a length having an end portion 10b extending from the heat fusion portion 1c, but the length L2 of the heat fusion portion 1c and the protective member 10 The length L1 may be equal. The allowable stroke amount L3-L1 needs to be large enough not to break the positive electrode terminal 3 and the negative electrode terminal 4 that are electrically connected as will be described later.

  The protective member 10 and the heat-sealed portion 1c of the laminate sheet 7 have a configuration in which the heat-fused portion 1c wraps and fixes the protective member 10 so that the protective member 10 is a core material of the heat-fused portion 1c. As shown in FIG. 3, even if an external force from the direction of arrow B is applied, the heat-sealed portion 1c is unlikely to be deformed. Moreover, it can fix more stably by winding the protection member 10 to the base part 1c vicinity of the heat-fusion part 1c, and making it follow the main body side surface 2a of the main body 2 of the laminated battery 1. FIG.

  As shown in FIG. 4A, the battery storage case 20 has a structure having two partition walls 21 provided in parallel between two side walls 22 and having openings 21a. The laminate type battery 1 is disposed in a main body storage section 24 between the partition walls 21 facing the main body 2, and the positive electrode terminal 3 and the negative electrode terminal 4 are stored in the battery so as to extend to the electrode cooling path 23 side. Housed in the case 20. As shown in FIG. 4 (b), the laminate type battery 1 is stacked and constitutes an assembled battery 1c ′ connected in series by electrically connecting the positive electrode terminal 3 and the negative electrode terminal 4 to each other. doing. In the electrode cooling path 23, cooling air for cooling the positive electrode terminal 3 and the negative electrode terminal 4 is supplied in the direction of arrow D from a cooling air supply unit (not shown). Cooling air for cooling the main body 2 of the laminated battery 1 is also supplied from the cooling air supply unit to the main body storage unit 24.

  The opening 21 a formed in the partition wall 21 flows in the amount of cooling air flowing in the electrode cooling path 23 to the main body storage portion 24 side, or conversely to the main body storage portion 24 side of the cooling air flowing in the main body storage portion 24. In order to limit the outflow amount, the width of the laminate type battery 1 is narrower than the width in the short direction and slightly wider than the widths of the positive electrode terminal 3 and the negative electrode terminal 4.

  For simplicity, the battery unit shown in FIG. 4 shows only one row of the laminate-type battery 1, and the opening 21 a of the partition wall 21 shows only one set corresponding to the illustrated laminate-type battery 1. However, in the battery unit, a plurality of assembled batteries 1 ′ are arranged in the Y direction in the figure according to the required amount of electric power, and the number of openings 21 a corresponding to this is formed in the partition wall 21. It becomes.

  Next, a state in which the laminate type battery 1 is moved in the main body storage portion 24 of the battery storage case 20 by vibration and the end surface 10c of the protection member 10 collides with the partition wall 21 will be described with reference to FIG.

  FIG. 5A is a schematic view showing a state in which the laminate type battery moves in the direction of arrow E in the main body housing portion due to vibration, and the end face of the protective member collides with the partition wall. It is the partially expanded view which expanded the X section of).

As shown in the drawing, the end surface 10 c of the protection member 10 abuts against the partition wall 21, so that the heat fusion part 1 c is prevented from directly colliding with the partition wall 21. Further, the collision energy received by the protection member 10 in the event of a collision is dispersed and absorbed by the protection member 10 and the heat-sealing part 1c that entrains and fixes the protection member 10. That is, according to the laminate type battery 1 of the present embodiment, the collision energy is not concentrated on a part of the laminate sheet as in the prior art, so that the occurrence of the crushing and cracking of the laminate sheet 7 can be prevented. Therefore, it is possible to prevent the electrolytic solution in the main body 2 from leaking.
(Second Embodiment)
FIG. 6 shows an external perspective view of a laminated battery provided with a protective member according to the present embodiment. FIG. 7 is a partially enlarged sectional view in the FF direction shown in FIG.

  Since the laminate type battery itself has basically the same structure as that described in the first embodiment, detailed description thereof will be omitted, and in the following description, it was used in the first embodiment. The description will be made using the same reference numerals.

  The protective member 110 has a long groove-shaped insertion portion 110d having a depth d in the longitudinal direction. That is, in the first embodiment, all of the protective members are illustrated as being wound and fixed by the heat-sealing portion 1c of the laminate sheet 7, but the protective member 110 of the present embodiment is thermally fused to the insertion portion 110d. The wearing part 1c is inserted and fixed to each other with an adhesive. It is preferable that the depth d of the insertion part 110d is formed deeper than the width W of the heat fusion part 1c. In this case, the protective member 110 can be stably fixed because it can be inserted up to the base 1c 'of the heat-sealing part 1c. Moreover, in the case of the protective member 110 of this embodiment, since it has the structure which coat | covers the heat sealing | fusion part 1c, the heat sealing | fusion part 1c is hard to be damaged.

  In addition, although the protective member 110 shown in FIG. 7 is shown as an example of an integrally configured member, the protective member 110 is composed of a member that is vertically divided by the insertion portion 110d and sandwiches the heat fusion portion 1c. It is good.

Similarly to the protective member 10 of the first embodiment, the protective member 110 of the present embodiment also has an end portion 110b of the protective member 110 extending from the heat-fused portion end 1c ″ of the heat-fused portion 1c, and an end face 110c. By contacting the partition wall 21, it is possible to prevent the heat fusion part 1 c from directly colliding with the partition wall 21, and to prevent the laminate sheet 7 from being crushed or cracked, so that the electrolyte in the main body 2 leaks. Can be prevented.
(Third embodiment)
FIG. 8 is a schematic partial enlarged view of a laminate type battery and a battery storage case provided with a buffer member for absorbing collision energy when the laminate type battery and the partition wall collide with each other.

  In the present embodiment, the laminate type battery and the battery storage case have basically the same structure as that described in the first embodiment, and therefore, detailed description thereof will be omitted and in the following description. Are described using the same reference numerals as those used in the first embodiment.

  8A is an example in which the buffer member 50 is attached to the end surface 10c of the protective member 10 having the configuration shown in the first embodiment, and FIG. 8B is an example in which the buffer member 51 is provided on the partition wall 21. FIG. 8C, the partition wall 21 has a buffer portion 52a that absorbs an impact in the collision direction (arrow G direction), and a side portion that prevents displacement of the laminated battery 1 in the side direction (arrow H direction). This is an example in which a buffer member 52 having 52b is provided. 8A to 8C, only one end side of the protective member 10 having the buffer member 50 and only one surface side of the partition wall 21 provided with the buffer members 51 and 52 are shown in an enlarged manner. However, the buffer member 50 is attached to both end faces of the protection member 10, and the buffer members 51 and 52 are also provided on the partition walls 21 on both sides. As the material of each of the buffer members 50, 51, 52, a member such as foaming urethane, rubber, etc., which is lightweight and has a good impact force absorption characteristic and is difficult to be plastically deformed is suitable.

  By applying the buffer members 50, 51, 52, impact energy at the time of collision can be effectively absorbed, so that the laminate sheet 7 can be prevented from being crushed and cracked. Electrolyte leakage can be prevented.

  In addition, although the buffer members 50, 51, and 52 shown in FIG. 8A to FIG. 8C have been described by taking the protective member 10 having the configuration shown in the first embodiment as an example, The protection member 110 shown can also be applied.

  In each of the above-described embodiments, the protective members 10 and 110 have been described as having two configurations per laminated battery, but the present invention is not limited to this, and there may be one or three or more. It may have.

1 is a schematic external perspective view of a laminated battery according to a first embodiment of the present invention. It is a schematic diagram which shows the formation method of the exterior body by a laminate sheet. FIG. 2 is a partially enlarged view of a portion where a protective member of the laminated battery according to the first embodiment of the present invention is attached as viewed from the direction of arrow A shown in FIG. 1. It is the typical top view and sectional drawing of the battery unit which accommodated the laminate type battery shown in FIG. 1 in the battery storage case. It is the schematic diagram which shows the state which the end surface of the protection member collided with the partition by vibration, and a partial enlarged view. It is an external appearance perspective view of the lamination type battery provided with the protection member of the 2nd Embodiment of this invention. It is a partially expanded sectional view of the FF direction shown in FIG. It is the typical partial enlarged view of the lamination type battery provided with the buffer member of the 3rd Embodiment of this invention, and a battery storage case. It is a typical external appearance perspective view of an example of the conventional lamination type battery. It is a mimetic diagram for explaining crushing of a lamination sheet of a lamination type battery stored in a battery storage case which can cool an electrode terminal and a battery body individually.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laminate type battery 1 'Battery assembly 1c Thermal fusion part 1c' Base part 1c "Thermal fusion part edge 1a, 1b, 1c Thermal fusion part 2 Main body 2a Main body side surface 3 Positive electrode terminal 4 Negative electrode terminal 7 Lamination Sheet 7a Bending part 7b Center seal part 10, 110 Protective member 10a Fixing part 10b, 110b End part 10c, 110c End face 11 Side 20 Battery storage case 21a Opening part 21 Bulkhead 22 Side wall 23 Electrode cooling path 24 Main body storage part 50, 51, 52 Buffer member 110d Insertion part

Claims (8)

An exterior body that includes electrode terminals that are electrically connected to a power generation element including an electrolytic solution and are arranged to face each other, and that is made of a laminate sheet, encloses the power generation element, is a first in which the electrode terminals extend. In a laminate type battery having a side and a second side extending in the arrangement direction of each electrode terminal,
It has at least one protection member whose length is longer than the length of the second side in the arrangement direction, and both end faces of the protection member extend from both ends of the second side in the arrangement direction. The laminated battery is fixed to the second side.   The laminate type battery according to claim 1, wherein the protection member is a rod-like member, and is wound around and fixed to the second side.   The laminated battery according to claim 1, wherein a long groove is formed in the protective member, and the protective member is fixed to the second side by inserting the second side into the long groove. An exterior body that has electrode terminals that are electrically connected to a power generation element including an electrolytic solution and are arranged to face each other, and is made of a laminate sheet and encloses the power generation element, is a first in which the electrode terminals extend. And a protective member for a laminate type battery having a second side extending in the arrangement direction of each electrode terminal,
A protective member for a laminate type battery, comprising buffer members on both end faces and having a length longer than the length of the second side in the arrangement direction. An exterior body that includes electrode terminals that are electrically connected to a power generation element including an electrolytic solution and are arranged to face each other, and that is made of a laminate sheet, encloses the power generation element, is a first in which the electrode terminals extend. And a protective member for a laminate type battery having a second side extending in the arrangement direction of each electrode terminal,
A protective member for a laminate type battery, wherein a length of the second side is longer than a length of the second side in the arrangement direction, and a long groove into which the second side is inserted is formed.   The protective member for a laminate-type battery according to claim 5, comprising buffer members on both end faces. In the battery unit in which at least one laminate type battery is accommodated between the wall surfaces arranged opposite to each other, and an opening portion is formed on the wall surface to extend the electrode terminal of the laminate type battery.
A battery unit comprising the laminated battery according to any one of claims 1 to 3 housed between the wall surfaces.   The battery unit according to claim 7, wherein a buffer member is provided on a portion of the wall surface corresponding to the both end surfaces of the protection member.

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