Discharge structure for low-melting-point material that melts during the roasting of battery packs.

Abstract

This invention provides a discharge structure for low-melting-point material that melts during the roasting process of a battery pack, which is advantageous for efficiently removing battery cells after the roasting process. [Solution] During battery pack recycling, the battery pack is roasted, and this roasting melts the spacer 22. When the spacer 22 melts, the closing member 24 and the fastening member 14 fall due to their own weight, and the locking member 18 comes into contact with the inner surface 1202A of the bottom wall 1202 around the fastening member insertion hole 16. The closing member 24 is positioned at a location lower than the outer surface 1202B of the bottom wall 1202, and the discharge hole 20, which is located at the lowest point of the bottom wall 1202, is opened.

Description

Technical Field

[0001] The present invention relates to a discharge structure of a low melting point material that melts during baking of a battery pack.

Background Art

[0002] In electric vehicles such as electric vehicles and hybrid vehicles using a motor as a drive source, a battery pack that supplies power to the motor is used (see Patent Document 1). The battery pack includes a battery assembly including a plurality of battery modules each composed of a plurality of battery cells, and a steel case that houses the battery assembly. The battery cell is a secondary battery, and the battery element is sealed in a cell case. The battery element is composed of an electrode material containing rare metals with limited production amounts such as lithium, cobalt, and nickel. Therefore, from the viewpoint of effective utilization of resources, it is important to disassemble used battery cells to recover rare metals and recycle the recovered rare metals as battery elements of battery cells. In recent years, in such recycling, a baking process has been performed in which the battery pack is heated to a baking temperature of about 400 to 600 degrees without disassembling the battery pack to vaporize and remove the electrolytic solution inside the battery cell. Then, the battery pack after the baking process is disassembled, the battery cells are taken out from the case, and rare metals are recovered.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Incidentally, the inside of the case contains various components made of low-melting-point materials with a melting point lower than the roasting temperature, such as aluminum, including cooling fins for electrical components, brackets for fixing battery cells, and the case for the battery module. As a result, the roasting process causes the low-melting-point materials to melt and accumulate at the bottom of the case. When low-melting-point material accumulates at the bottom of the case, removing the battery cells from the accumulated material becomes a time-consuming process, and some kind of improvement is needed. The present invention has been made in view of the above circumstances, and aims to provide a discharge structure for low-melting-point material that melts during the roasting of a battery pack, which is advantageous for efficiently removing battery cells after the roasting process. [Means for solving the problem]

[0005] To achieve the above objective, one embodiment of the present invention provides at least two fastening member insertion holes provided at intervals in the wall portion constituting the battery case of the battery pack; a discharge hole provided in the wall portion located between the fastening member insertion holes; a plurality of spacers provided with spacer fastening member insertion holes and positioned on the inner surface of the wall portion located inside the battery case at the locations where the fastening member insertion holes are located; a locking member provided on each of the spacers and having a fastening member coupling hole, capable of locking to the inner surface of the wall portion surrounding the fastening member insertion hole; and the outer surface of the wall portion located outside the battery case, having a size that covers each of the fastening member insertion holes and the discharge hole. The battery case is equipped with a plurality of fastening members, each having a head and a shaft portion protruding from the head, wherein the shaft portion is inserted from the outside to the inside of the battery case into the fastening member insertion hole for the fastening member, the fastening member insertion hole, and the spacer fastening member insertion hole, and the shaft portion is coupled to the locking member via the fastening member coupling hole, thereby bringing the spacer into contact with the inner surface of the wall portion and the fastening member into contact with the outer surface of the wall portion, thereby closing the fastening member insertion hole and the discharge hole, wherein the spacer is formed of a material with a lower melting point than the wall portion, the fastening member, the locking member, and the fastening member. Furthermore, one embodiment of the present invention is characterized in that two fastening member insertion holes are provided, and the two spacers, each positioned on the inner surface of the wall portion at the location of the fastening member insertion holes, have different thicknesses. Furthermore, in one embodiment of the present invention, the fastening member insertion holes are provided in three locations such that they are at the vertices of a triangle when viewed from above, and three fastening members are also provided, the discharge holes are provided so as to be located inside the triangle, the thickness of the two spacers placed in the two fastening member insertion holes located at the vertices of both ends of one side of the triangle is the same, and the thickness of the one spacer placed in the fastening member insertion hole located at the remaining vertex is smaller than the thickness of the two spacers. Furthermore, in one embodiment of the present invention, the closing member is provided with three fastening member insertion holes for the closing member so as to be located at the vertices of a triangle when viewed from above, and a groove is provided on the inner surface of the closing member that abuts against the outer surface of the wall portion, passing between the two fastening member insertion holes for the closing member located at the vertices of both ends of one side of the triangle, and extending from the outer edge of the closing member toward the remaining fastening member insertion hole for the closing member. Furthermore, one embodiment of the present invention is characterized in that the width of the groove differs on the inner surface of the blocking member between the outer edge side of the blocking member and the discharge hole. Furthermore, in one embodiment of the present invention, the spacer comprises a spacer body disposed at a location on the inner surface of the wall portion where the fastening member insertion hole is located, and a spacer cylindrical portion having an outer diameter that protrudes from the spacer body and is inserted into the fastening member insertion hole, and the spacer fastening member insertion hole is formed extending from the spacer body to the spacer cylindrical portion. Furthermore, one embodiment of the present invention is characterized in that two fastening member insertion holes are provided, and the two spacer bodies, each positioned on the inner surface of the wall portion where the fastening member insertion holes are located, have different thicknesses. [Effects of the Invention]

[0006] According to one embodiment of the present invention, when the spacer melts due to the roasting of the battery pack, the locking member, the closing member, and the fastening member fall, and the discharge hole opens. As a result, the low-melting-point material inside the battery case falls downward through the discharge hole along with the molten spacer and flows out onto the closing member. Therefore, during battery pack recycling, it becomes possible to melt low-melting-point materials with melting points lower than the roasting temperature, such as aluminum alloys, and discharge them to the outside of the battery case through the discharge holes, which is advantageous for easily recovering rare metals. Furthermore, by providing two fastening member insertion holes and arranging the thickness of the two spacers, each positioned at the location of the fastening member insertion holes on the inner surface of the wall, when the spacers are melted by the roasting of the battery pack, the sealing member becomes inclined at a point lower than the outer surface of the wall. This allows the low-melting-point material, including the spacers, to flow out from the lowest point of the inclined sealing member's outer edge, which is advantageous for easily recovering the low-melting-point material. Furthermore, by providing three fastening member insertion holes located at the vertices of a triangle when viewed from above, and also providing three fastening members, and by providing a discharge hole located inside the triangle, and by making the thickness of the two spacers placed in the two fastening member insertion holes located at the vertices of one side of the triangle the same, and making the thickness of the one spacer placed in the fastening member insertion hole at the remaining vertex smaller than the thickness of the two spacers, when the spacers are melted by the roasting of the battery pack, the closure member will be inclined at a point away from the outer surface of the wall, and the low-melting-point material including the spacers will flow out from the lowest point of the inclined closure member's outer edge, which is advantageous for easily recovering the low-melting-point material. In addition, since three fastening members are used, it is advantageous for more firmly attaching the closure member to the wall. Furthermore, if the closure member is provided with three fastening member insertion holes for the closure member, positioned at the vertices of a triangle when viewed from above, and if a groove is provided on the inner surface of the closure member that abuts the outer surface of the wall, extending from the outer edge of the closure member towards the remaining fastening member insertion hole, passing between the two fastening member insertion holes located at the vertices of one side of the triangle, then when the spacer is melted by the roasting of the battery pack, a large amount of molten low-melting-point material is guided into the groove by the two male screw portions and flows out from the outer edge of the closure member through the groove, which is advantageous for easily recovering the molten low-melting-point material. Furthermore, if the width of the groove differs between the outer edge of the closure member and the discharge hole on the inner surface of the closure member, it is advantageous for efficiently recovering the molten low-melting-point material. Furthermore, if the spacer comprises a spacer body and a spacer cylinder portion having an outer diameter that protrudes from the spacer body and is inserted into a fastening member insertion hole, and a spacer fastening member insertion hole is formed from the spacer body to the spacer cylinder portion through which a male threaded portion is inserted, it is advantageous in ensuring that the fastening member insertion hole is reliably closed by press-fitting the spacer cylinder portion into the fastening member insertion hole when positioning the spacer body on the inner surface of the bottom wall. Furthermore, by providing two fastening member insertion holes and making the thickness of the two spacer bodies, which are positioned on the inner surface of the wall at the locations of the fastening member insertion holes, different, when the spacers are melted by the roasting of the battery pack, the closing member will be inclined at a point away from the outer surface of the wall. The low-melting-point material, including the spacers, will flow out from the lowest point of the inclined closing member's outer edge, which is advantageous for easily recovering the low-melting-point material. [Brief explanation of the drawing]

[0007] [Figure 1] This is a longitudinal cross-sectional view of a discharge structure for low-melting-point material according to the first embodiment. [Figure 2] This is a plan view of Figure 1. [Figure 3] This is a longitudinal cross-sectional view of the spacer after melting in the discharge structure for low-melting-point material according to the first embodiment. [Figure 4] This is a longitudinal cross-sectional view of a low-melting-point material discharge structure according to a second embodiment. [Figure 5] This is a longitudinal cross-sectional view of the spacer after melting in the discharge structure for low-melting-point material according to the second embodiment. [Figure 6] This is a longitudinal cross-sectional view of the discharge structure for low-melting-point material according to the third embodiment, and corresponds to the cross-sectional view along line AA in Figure 7. [Figure 7] This is a plan view of Figure 6. [Figure 8] This is a cross-sectional view of the closure member, corresponding to the cross-section along line BB in Figure 7. [Figure 9] This is a longitudinal cross-sectional view of the spacer after melting in the discharge structure for low-melting-point material according to the third embodiment. [Modes for carrying out the invention]

[0008] (First Embodiment) Referring to FIGS. 1 - 3, a first embodiment of the present invention will be described. The discharge structure (hereinafter referred to as the low melting point material discharge structure) 100A of the low melting point material melted during baking of the battery pack of this embodiment is mounted on an electric vehicle using only a motor as a drive source, or a hybrid vehicle, or an electric vehicle using a motor as a drive source such as a plug-in hybrid vehicle capable of external charging or external power supply, and is applied to the battery case of the battery pack that supplies power to the above motor.

[0009] As shown in FIGS. 1 and 2, the battery pack includes a battery case 10, a battery pack (not shown) composed of a plurality of battery modules housed in this battery case 10, a control device (not shown) for controlling the battery pack, a DC / DC converter (not shown), a cooling device (not shown) for cooling the battery module, and the like. The battery case 10 is made of steel and includes a battery tray 12 with an open upper part and a battery cover (not shown) for closing the upper part of the battery tray 12. The battery tray 12 includes a bottom wall 1202 and a peripheral wall (not shown) standing up from the periphery of the bottom wall 1202. On the bottom wall 1202, a battery pack, a control device, a DC / DC converter, a cooling device, etc., which are all not shown, are housed. The bottom wall 1202 has an inner surface 1202A of the wall part located inside the battery case 10 and an outer surface 1202B of the wall part located outside the battery case 10.

[0010] In this embodiment, the center of the bottom wall 1202 is the lowest position among the bottom wall 1202. Then, during the baking of the battery pack, various components made of low-melting-point materials with melting points lower than the baking temperature, such as cooling fins for electrical components provided inside the battery case 10 of the battery pack, brackets for fixing battery cells, and cases of battery modules, are melted, and a discharge structure 100A for the melted low-melting-point material is provided at the center of the bottom wall 1202. The discharge structure 100A for the low-melting-point material includes a fastening member 14, a fastening member insertion hole 16, a locking member 18, a discharge hole 20, a spacer 22, and a closing member 24.

[0011] As shown in FIGS. 1 and 2, two fastening member insertion holes 16 are provided with a space therebetween, sandwiching the center of the bottom wall 1202 that constitutes the wall portion of the battery case 10 of the battery pack. As the fastening member 14, various conventionally known ones such as bolts and steel rivets can be used. In the present embodiment, a steel bolt is used as the fastening member 14. The fastening member 14 includes a hexagonal head 1402 and a male screw portion 1404 as a shaft portion protruding from the lower surface of the head 1402. The discharge hole 20 is provided at the center of the bottom wall 1202 that constitutes the wall portion of the battery case 10 of the battery pack, and is located at the lowest position among the bottom walls 1202. In the present embodiment, two fastening members 14 are used. Correspondingly, two fastening member insertion holes 16 are provided in the bottom wall 1202, and the two fastening member insertion holes 16 are provided at positions facing each other with the discharge hole 20 interposed therebetween. Therefore, the discharge hole 20 is located between the two fastening member insertion holes 16. The fastening member 14 is inserted into the fastening member insertion hole 16 from the outside to the inside of the battery case 10.

[0012] The spacer 22 is disposed on the inner surface 1202A of the wall portion of the bottom wall 1202 where the fastening member insertion hole 16 is located. The spacer 22 may be circular, rectangular, or polygonal in plan view. In the present embodiment, the spacer 22 has a disk shape, a spacer fastening member insertion hole 26 is formed at the center, and has a thickness. Furthermore, in this embodiment, the thickness T1 of one spacer 22 is formed to be larger than the thickness T2 of the other spacer 22. The spacer 22 is made of a low-melting-point material that melts during the roasting process for recycling the battery pack. In other words, the spacer 22 is made of a low-melting-point material that has a melting point similar to that of various components such as cooling fins for electrical components that are melted during the baking of the battery pack, brackets for fixing battery cells, and cases for battery modules. Examples of low-melting-point materials that make up the spacer 22 include aluminum alloys, rubber, and synthetic resins. In this embodiment, an aluminum alloy is used as the spacer 22. Furthermore, the roasting temperature during the recycling of the battery pack is set to a temperature above the melting point of the low-melting-point material used for the spacer 22. The locking members 18 are positioned inside the battery case 10, each on top of the spacers 22. The locking member 18 is made of steel and has a female threaded portion 1802 which serves as a fastening member connection hole that screws into a male threaded portion 1404 that protrudes from the spacer fastening member insertion hole 26, and is sized to abut against the inner surface 1202A of the wall portion surrounding the fastening member insertion hole 16.

[0013] The blocking member 24 is made of steel. Therefore, the spacer 22 is made of a material with a lower melting point than the bottom wall (wall portion) 1202, the fastening member 14, the locking member 18, and the closing member 24. The sealing member 24 is positioned on the outer surface 1202B of the bottom wall 1202 of the battery case 10, and is sized to cover the two fastening member insertion holes 16 and the discharge hole 20. A fastening member insertion hole 2402 for the sealing member is provided at a location corresponding to the two fastening member insertion holes 16.

[0014] Spacers 22 are placed on the inner surface 1202A of the bottom wall 1202 at the locations where the two fastening member insertion holes 16 are located, and a closing member 24 is placed on the outer surface 1202B of the bottom wall 1202 so as to cover the discharge hole 20 and the two fastening member insertion holes 16. The male threaded portions 1404 of two fastening members 14 are inserted from the outside to the inside of the battery case 10 into the fastening member insertion hole 2402 for the closing member, the fastening member insertion hole 16, and the fastening member insertion hole 26 for the spacer, respectively, and the female threaded portion 1802 of the locking member 18 is screwed onto the male threaded portion 1404 of each fastening member 14 to fasten them. If rivets or the like are used as fastening members 14, the tip of the shaft of the rivet protruding from the fastening member coupling hole (1802) is crushed, and the rivet is coupled to the closing member 24 via the fastening member coupling hole (1802). As a result, the spacer 22 is held between the locking member 18 and the inner surface 1202A of the wall portion of the battery case 10, and the closing member 24 is held between the head 1402 of the fastening member 14 and the outer surface 1202B of the wall portion, thereby closing the discharge hole 20, the fastening member insertion hole 2402 for the closing member, and the fastening member insertion hole 16. In this embodiment, a sealing member 28 is interposed between the closing member 24 and the outer surface 1202B of the bottom wall 1202 around the discharge hole 20, surrounding the discharge hole 20. The sealing member 28 is optional.

[0015] Next, I will explain the effects and benefits. During the recycling of the battery pack, it is roasted, and this roasting process melts the spacer 22. When the spacer 22 melts, as shown in Figures 1 and 3, the locking member 18, the closing member 24, and the fastening member 14 fall due to their own weight, the locking member 18 comes into contact with the inner surface 1202A of the bottom wall 1202 around the fastening member insertion hole 16, the closing member 24 is located at a point below the outer surface 1202B of the bottom wall 1202, and the discharge hole 20 located at the lowest point of the bottom wall 1202 is opened. In this embodiment, since the thicknesses T1 and T2 of the spacer 22 are set to different values, the closing member 24 is inclined at a point where it is located away from the outer surface 1202B of the bottom wall 1202. Low-melting-point materials such as cooling fins for electrical components, brackets for fixing battery cells, and battery module cases, which have a melting point lower than the roasting temperature and are in a molten state within the battery case 10, fall downward through the discharge hole 20 along with the molten spacers 22 and flow out onto the blocking member 24. In this case, since the blocking member 24 is inclined, the low-melting-point material flows out from the lower part of the blocking member 24, which is advantageous for easily recovering the low-melting-point material. Therefore, when recycling the battery pack, it becomes possible to melt low-melting-point materials with a melting point lower than the roasting temperature, such as aluminum alloys, and discharge them to the outside of the battery case 10 through the fastening member insertion hole 16, which is advantageous for easily recovering rare metals. Although the spacer 22 may be formed with equal thicknesses T1 and T2, in this case the blocking member 24 will be parallel to the bottom wall 1202 at a point away from the bottom wall 1202, and the low-melting-point material will flow out from the entire circumference of the blocking member 24, requiring a recovery container with a larger opening.

[0016] (Second Embodiment) Next, a discharge structure 100B for low-melting-point material according to a second embodiment will be described with reference to Figures 4 and 5. In the following description of the embodiments, the same reference numerals are used for parts and components as in the first embodiment, and their descriptions are simplified or omitted. The focus will be on describing the parts that differ from the first embodiment. In the second embodiment, the shape of the spacer 22 is different from that of the first embodiment. As shown in Figure 4, the two spacers 22 each consist of a spacer body 22A positioned on the inner surface 1202A of the wall and a spacer cylindrical portion 22B protruding from the spacer body 22A and having an outer diameter that allows it to be inserted into the fastening member insertion hole 16 without rattling. A spacer fastening member insertion hole 26 is formed through the spacer body 22A and the spacer cylindrical portion 22B, through which a male threaded portion 1404 is inserted. In the second embodiment, the spacer bodies 22A of the two spacers 22 are placed on the inner surface 1202A of the wall portion surrounding the fastening member insertion hole 16, and the spacer cylindrical portion 22B is inserted into the fastening member insertion hole 16. The male threaded portion 1404, which serves as the shaft portion of the fastening member 14, is inserted from the fastening member insertion hole 2402 for the closing member and the fastening member insertion hole 16 to the spacer fastening member insertion hole 26. The male threaded portion 1404 of the fastening member 14 is screwed into the female threaded portion 1802 of the locking member 18, which serves as the fastening member coupling hole, and the discharge hole 20 is closed by the closing member 24 via the sealing member 28.

[0017] This second embodiment also provides the same effects as the first embodiment, as well as the following effects. In the second embodiment, since the spacer cylinder portion 22B is inserted into the fastening member insertion hole 16, the inner diameter of the fastening member insertion hole 16 can be made larger. Therefore, as shown in Figure 5, when the spacer 22 melts during roasting, the range in which the male thread portion 1404 directly below the head 1402 of the fastening member 14 can tilt within the fastening member insertion hole 16 becomes larger, which is advantageous in obtaining a greater inclination of the closing member 24 when the closing member 24 is inclined at a point further down from the outer surface 1202B of the bottom wall 1202. Furthermore, forming the outer diameter of the spacer cylinder portion 22B to a size that allows it to be press-fitted into the fastening member insertion hole 16, and then press-fitting the spacer cylinder portion 22B into the fastening member insertion hole 16 when positioning the spacer body 22A on the inner surface 1202A of the bottom wall 1202, is advantageous in ensuring that the fastening member insertion hole 16 is properly closed.

[0018] (Third embodiment) Next, a discharge structure 100C for low-melting-point material according to a third embodiment will be described with reference to Figures 6-9. The third embodiment differs from the first embodiment in that it uses three fastening members 14 and has grooves 30 formed in the closing member 24 to guide the molten low-melting-point material. The low-melting-point material discharge structure 100C comprises three steel fastening members 14, three fastening member insertion holes 16, one discharge hole 20, three spacers 22, three steel locking members 18, one steel closing member 24, and one groove 30 for guiding the molten low-melting-point material.

[0019] The fastening member insertion holes 16 and the fastening member insertion holes 2402 for the closing member are provided in three locations so as to be at the vertices of a triangle when viewed from above, and there are also three fastening members 14 and three locking members 18. In this embodiment, an equilateral triangle or an isosceles triangle is used as the triangle. The discharge hole 20 is located inside the triangle, specifically in the center of the triangle in this embodiment. Three spacers 22 are also provided, and each spacer 22 is provided with a spacer fastening member insertion hole 26. The thickness T1 of the spacers 22 placed at the vertices at both ends of one side of the triangle is greater than the thickness T2 of the spacers 22 placed at the remaining vertices.

[0020] The closure member 24 is formed to cover the discharge hole 20 and the three closure member fastening member insertion holes 2402. A groove 30 is provided on the inner surface 2404 of the closing member 24 that abuts against the outer surface 1202B of the wall portion. The groove 30 extends from the outer edge of the closing member 24 toward the remaining closing member fastening member insertion hole 2402, passing between the two fastening member insertion holes 2402 located at the vertices of both ends of one side of the triangle. The bottom surface 3002 of the groove 30 is formed as an inclined surface that gradually becomes lower towards the outer edge of the closing member 24. Furthermore, the width of the groove 30 is formed to gradually decrease as it approaches the outer edge of the closing member 24. In other words, the width of the groove 30 differs on the inner surface 2404 of the closing member 24 between the outer edge side of the closing member 24 and the side facing the discharge hole 20.

[0021] Three spacers 22 are placed on the inner surface 1202A of the wall portion where each fastening member insertion hole 16 is located, a locking member 18 is placed on top of these spacers 22, and a closing member 24 is placed on the outer surface 1202B of the wall portion so as to cover the discharge hole 20 and the three fastening member insertion holes 16. Then, the male threaded portion 1404 of the fastening member 14 is inserted through the fastening member insertion hole 16 and the spacer fastening member insertion hole 26 from the fastening member insertion hole 2402 for the closing member, and is screwed into the female thread of the closing member 24, so that the discharge hole 20 is closed by the closing member 24 via the sealing member 28, and the fastening member insertion hole 16 is closed by the spacer 22 and the head 1402 of the closing member 24.

[0022] During the recycling of the battery pack, the battery pack is roasted, and this roasting process melts the spacer 22 along with the cooling fins for the electrical components made of low-melting-point material, the brackets that secure the battery cells, and the battery module case. When the spacer 22 melts, the locking member 18, the closing member 24, and the fastening member 14 fall, similar to the first embodiment. Since the thicknesses T1 and T2 of the spacer 22 are set to different values, the closing member 24 becomes inclined at a point away from the outer surface 1202B of the bottom wall 1202. The low-melting-point material, including the spacer 22, flows out from the outer edge of the closing member 24, which is the lowest point of the inclined state, which is advantageous for easily recovering the low-melting-point material. Furthermore, since grooves 30 are provided on the inner surface 2404 of the inclined and lowered closure member 24, a large amount of molten low-melting-point material is guided into the grooves 30 by the two male screw portions 1404 and flows out from the outer edge of the closure member 24 through the grooves 30, which is advantageous for easily recovering the molten low-melting-point material. Furthermore, since the width of the groove 30 is formed to decrease as it approaches the outer edge of the closure member 24, the width of the outlet for the molten low-melting-point material can be narrowed, allowing the use of a recovery container with a small opening, which is advantageous for efficiently recovering the molten low-melting-point material. Furthermore, since three fastening members 14 are used, it is advantageous to attach the closing member 24 more firmly to the bottom wall 1202 of the battery case 10 compared to the second embodiment. Therefore, when recycling battery packs, it becomes possible to melt low-melting-point materials with melting points lower than the roasting temperature, such as aluminum alloys, and discharge them to the outside of the battery case 10, which is advantageous in easily recovering rare metals.

[0023] Furthermore, in the case where the width of the groove 30 differs on the inner surface 2404 of the closing member 24 between the outer edge side of the closing member 24 and the discharge hole 20 side, the width of the groove 30 may be formed to increase as it approaches the outer edge of the closing member 24. In this case, an area for heat reception of the molten low-melting-point material guided by the groove 30 can be secured, thereby ensuring the fluidity of the molten low-melting-point material and being advantageous for efficiently recovering the molten low-melting-point material. Furthermore, the groove 30 may be omitted, and the thickness of the three spacers 22 may be made equal. However, providing the groove 30 and making the thickness of the spacers 22 different, as in this embodiment, is advantageous for efficiently recovering the molten low-melting-point material.

[0024] Alternatively, as in the second embodiment, a spacer 22 having a spacer body 22A and a spacer cylindrical portion 22B may be used. When such a spacer 22 is used, the spacer cylindrical portion 22B is inserted into the fastening member insertion hole 16, which allows the inner diameter of the fastening member insertion hole 16 to be made larger. Therefore, during the roasting of the battery pack, the range in which the male thread portion 1404 directly below the head 1402 of the fastening member 14 can tilt within the fastening member insertion hole 16 becomes larger, which is advantageous in obtaining a greater inclination of the closing member 24 when the closing member 24 is inclined at a point further down from the outer surface 1202B of the bottom wall 1202. Furthermore, forming the outer diameter of the spacer cylinder portion 22B to a size that allows it to be press-fitted into the fastening member insertion hole 16, and then press-fitting the spacer cylinder portion 22B into the fastening member insertion hole 16 when positioning the spacer body 22A on the inner surface 1202A of the bottom wall 1202, is advantageous in ensuring that the fastening member insertion hole 16 is properly closed. [Explanation of Symbols]

[0025] Discharge structure for 100A-100C low-melting point materials 10 Battery Cases 12 Battery tray 1202 Bottom wall 1202A Inner surface of the wall 1202B Wall exterior 14 Fastening members 1402 Head 1404 Male threaded section 16 Fastening member insertion hole 18 Locking member 1802 Female thread section 20 Discharge hole 22 Spacers 22A Spacer Body 22B Spacer cylinder section 24 Closure member 2402 Fastening member insertion hole for closure member 26 Spacer fastening member insertion hole 28 sealing member 30 grooves

Claims

1. At least two fastening member insertion holes are provided at intervals in the wall portion constituting the battery case of the battery pack, A discharge hole is provided in the wall portion located between the fastening member insertion holes, Multiple spacers are provided with fastening member insertion holes for spacers and are arranged on the inner surface of the wall portion located inside the battery case at the locations where the fastening member insertion holes are located, Each of the aforementioned spacers is positioned on top of the aforementioned spacers, and each has a fastening member connection hole and a locking member that can be engaged with the inner surface of the wall portion surrounding the fastening member insertion hole, A closing member having a size that covers each of the fastening member insertion holes and the discharge holes, positioned on the outer surface of the wall portion located outside the battery case, and having fastening member insertion holes for closing members at locations corresponding to each of the fastening member insertion holes, The battery case comprises a head and a shaft portion protruding from the head, wherein the shaft portion is inserted from the outside to the inside of the battery case through the fastening member insertion hole for the closing member, the fastening member insertion hole, and the fastening member insertion hole for the spacer, and the shaft portion is connected to the locking member via the fastening member coupling hole, thereby bringing the spacer into contact with the inner surface of the wall portion and the closing member into contact with the outer surface of the wall portion, thereby closing the respective fastening member insertion holes and the discharge hole, and a plurality of fastening members The spacer is made of a material with a lower melting point than the wall portion, the fastening member, the locking member, and the closing member. A discharge structure for low-melting-point material that melts during the roasting of a battery pack, characterized by the above.

2. Two fastening member insertion holes are provided. The two spacers, each positioned on the inner surface of the wall portion at the location of the fastening member insertion hole, have different thicknesses. A discharge structure for low-melting-point material that is melted during roasting of a battery pack according to feature 1.

3. The fastening member insertion holes are provided in three locations, positioned at the vertices of a triangle when viewed from above, and three fastening members are also provided. The discharge hole is provided so as to be located inside the triangle. The thickness of the two spacers, which are positioned in the two fastening member insertion holes located at the vertices of both ends of one side of the triangle, is the same. The thickness of one of the spacers positioned in the fastening member insertion hole at the remaining vertex is smaller than the thickness of the two spacers. A discharge structure for low-melting-point material that is melted during roasting of a battery pack according to feature 1.

4. The aforementioned closing member is provided with three fastening member insertion holes for the closing member, which are positioned at the vertices of a triangle when viewed from above. A groove is provided on the inner surface of the closing member that abuts against the outer surface of the wall portion, passing between the two fastening member insertion holes for the closing member located at the vertices of both ends of one side of the triangle, and extending from the outer edge of the closing member toward the remaining fastening member insertion hole for the closing member. The battery pack according to feature 3, with a discharge structure for low-melting-point material that is melted during roasting.

5. The width of the groove differs on the inner surface of the blocking member between the outer edge side of the blocking member and the discharge hole side. The discharge structure for low-melting-point material that melts during roasting of the battery pack according to feature 4.

6. The spacer comprises a spacer body positioned on the inner surface of the wall portion where the fastening member insertion hole is located, and a spacer cylindrical portion having an outer diameter that protrudes from the spacer body and is inserted into the fastening member insertion hole. The fastening member insertion hole for the spacer is formed extending from the spacer body to the spacer cylindrical portion. A discharge structure for low-melting-point material that is melted during roasting of a battery pack according to feature 1.

7. Two fastening member insertion holes are provided. The two spacer bodies, each positioned on the inner surface of the wall portion where the fastening member insertion hole is located, have different thicknesses. The battery pack according to feature 6, with a discharge structure for low-melting-point material that is melted during roasting.

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