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] When the spacer 18 melts, the closing member 20 and the fastening member 14 fall due to their own weight, and a flow passage 22 is formed between the lower surface of the head 1402 and the inner surface 1202A of the wall portion, with multiple grooves 26 extending from the outside of the head 1402 to the annular flow passage 24. Due to the fall of the fastening member 14, the closing member 20 is positioned away from the outer surface of the bottom wall 1202, opening the lower end of the annular flow passage 24 located at the lowest point of the bottom wall 1202. The low-melting-point material, which has a melting point lower than the roasting temperature inside the battery case 10, flows through the flow passage 22 to the annular flow passage 24 together with the molten spacer 18, and flows out downward from the lower end of the annular flow passage 24.

Description

Technical Field

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[0003] ,

[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, during 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 it to vaporize and remove the electrolytic solution inside the battery cell. Then, the battery pack after the baking process is disassembled to remove the battery cells from the case and recover the rare metals.

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 battery pack 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 of the roasting process, the low-melting-point materials 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 a fastening member insertion hole provided in the wall portion constituting the battery case of a battery pack; a spacer having a spacer fastening member insertion hole, positioned on the inner surface of the wall portion located inside the battery case at the location of the fastening member insertion hole; a closing member having a size that covers the fastening member insertion hole, positioned on the outer surface of the wall portion located outside the battery case, and having a fastening member coupling hole formed therein; and a head portion and a shaft portion protruding from the head portion, wherein the shaft portion is inserted from the inside to the outside of the battery case into the spacer fastening member insertion hole and the fastening member insertion hole, and the shaft portion passes through the fastening member coupling hole to the closing portion The fastening member comprises a material that, when bonded to the material, causes the spacer to abut against the inner surface of the wall portion and the closing member to abut against the outer surface of the wall portion, thereby closing the fastening member insertion hole, wherein the spacer is made of a low-melting-point material with a lower melting point than the wall portion, the fastening member, and the closing member, and the fastening member insertion hole is formed in such a way that a flow path is formed between the shaft portion and the inner circumferential surface of the fastening member insertion hole through which the molten low-melting-point material, including the spacer, can flow, and when the spacer has melted and the lower surface of the head of the fastening member is in contact with the inner surface of the wall portion surrounding the fastening member insertion hole, a flow passage is provided between the lower surface of the head and the inner surface of the wall portion, from the outside of the head to the flow path. Furthermore, in one embodiment of the present invention, the spacer comprises a spacer body disposed on the inner surface of the wall portion and a spacer cylindrical portion having an outer diameter that protrudes from the spacer body and is inserted into the fastening member insertion hole, wherein the spacer fastening member insertion hole is formed extending from the spacer body to the spacer cylindrical portion. Furthermore, in one embodiment of the present invention, a fastening member insertion hole is provided in the wall portion constituting the battery case of the battery pack; a spacer is located inside the battery case and is positioned on the inner surface of the wall portion where the fastening member insertion hole is located and has a spacer fastening member insertion hole; a locking member is positioned on the spacer and has a fastening member coupling hole and can be locked to the inner surface of the wall portion surrounding the fastening member insertion hole; and the locking member has 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 and the spacer fastening member insertion hole, and the shaft portion is coupled to the locking member via the fastening member coupling hole. The fastening member comprises a spacer that abuts against the inner surface of the wall portion and a head that abuts against the outer surface of the wall portion to close the fastening member insertion hole, wherein the spacer is made of a low-melting-point material with a lower melting point than the wall portion, the fastening member, and the locking member, and the fastening member insertion hole is formed to a size that allows a flow path to be formed between the shaft portion and the inner circumferential surface of the fastening member insertion hole for the molten low-melting-point material, including the spacer, to flow, and when the spacer has melted and the lower surface of the locking member abuts against the inner surface of the wall portion around the fastening member insertion hole, a flow passage is provided between the lower surface of the locking member and the inner surface of the wall portion, from the outside of the locking member to the flow path. Furthermore, in one embodiment of the present invention, the spacer comprises a spacer body disposed on the inner surface of the wall portion and a spacer cylindrical portion having an outer diameter that protrudes from the spacer body and is inserted into the fastening member insertion hole, wherein 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 a washer is provided through which the male threaded portion of the fastening member is inserted and which is sandwiched between the outer surface of the wall portion and the head of the fastening member around the fastening member insertion hole, thereby closing the fastening member insertion hole together with the head of the fastening member. [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 closure member and fastening member fall, and a flow passage is formed between the lower surface of the head and the inner surface of the wall, from the outside of the head to the flow passage. In addition, the fall of the fastening member opens the lower end of the annular flow passage. As a result, the low-melting-point material inside the battery case, together with the molten spacer, flows from the flow passage to the annular flow passage and flows downward from the lower end of the annular flow passage. 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 fastening member insertion holes, which is advantageous for easily recovering rare metals. 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 the fastening member insertion hole, and the spacer fastening member insertion hole is formed extending from the spacer body to the spacer cylinder portion, even if the inner diameter of the fastening member insertion hole is formed to be larger than usual to secure a larger cross-sectional area of ​​the annular flow path, the male thread portion can be easily positioned in the center of the fastening member insertion hole by inserting the male thread portion into the spacer fastening member insertion hole. This is advantageous in securing a large tightening force by the fastening member and ensuring reliable closure of the fastening member insertion hole by the closure member. Furthermore, according to one embodiment of the present invention, when the spacer melts due to the roasting of the battery pack, the locking member falls together with the fastening member, and the lower surface of the locking member locks into the inner surface of the wall surrounding the fastening member insertion hole. Since a flow passage is provided between the lower surface of the locking member and the inner surface of the wall, from the outside of the locking member to the flow path, the low-melting-point material inside the battery case, together with the molten spacer, flows from the flow passage to the flow path and out downward from the lower end of the flow path. 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 fastening member insertion holes, which is advantageous for easily recovering rare metals. Furthermore, if the spacer comprises a spacer body and a spacer cylinder portion that protrudes from the spacer body and has an outer diameter through which a male threaded portion is inserted into the fastening member insertion hole, even if the inner diameter of the fastening member insertion hole is formed to be larger than usual to secure a larger cross-sectional area of ​​the annular flow path, inserting the male threaded portion into the spacer fastening member insertion hole allows the male threaded portion to be easily positioned in the center of the fastening member insertion hole. This is advantageous in securing a large tightening force by the fastening member and ensuring reliable closure of the fastening member insertion hole by the closure member. Furthermore, providing a washer through which the shaft portion of the fastening member is inserted and which is sandwiched between the outer surface of the wall portion and the head of the fastening member around the fastening member insertion hole, thereby closing the fastening member insertion hole, is advantageous in ensuring that the fastening member insertion hole is closed more reliably. [Brief explanation of the drawing]

[0007] [Figure 1] This is a plan view showing the central part of the bottom wall of a battery case provided with a low-melting-point material discharge structure according to the first embodiment. [Figure 2] This is a cross-sectional view along line AA in Figure 1. [Figure 3] This is a longitudinal cross-sectional view of a discharge structure for low-melting-point material according to the first embodiment. [Figure 4] This is a plan view of Figure 3. [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 first embodiment. [Figure 6] (A) is a front view of the fastening member of the discharge structure for low-melting-point material according to the second embodiment, and (B) is a bottom view of (A). [Figure 7] (A) is a longitudinal cross-sectional view of the low-melting-point material discharge structure according to the second embodiment, and (B) is a longitudinal cross-sectional view of (A) after the spacer has melted. [Figure 8] This is a longitudinal cross-sectional view of a discharge structure for low-melting-point material according to a third embodiment. [Figure 9] This is a plan view of the discharge structure for low-melting-point material according to the third embodiment. [Figure 10]It is a longitudinal sectional view after spacer melting of the low melting point material discharge structure according to the third embodiment. [Figure 11] It is a longitudinal sectional view of the low melting point material discharge structure according to the fourth embodiment. [Figure 12] It is a plan view of the low melting point material discharge structure according to the fourth embodiment. [Figure 13] It is a longitudinal sectional view after spacer melting of the low melting point material discharge structure according to the fourth embodiment. [Figure 14] (A) is a sectional view of the locking member of the low melting point material discharge structure according to the fifth embodiment, and (B) is a bottom view of the locking member. [Figure 15] It is a longitudinal sectional view of the low melting point material discharge structure according to the fifth embodiment. [Figure 16] It is a plan view of the low melting point material discharge structure according to the fifth embodiment. [Figure 17] It is a longitudinal sectional view after spacer melting of the low melting point material discharge structure according to the fifth embodiment. [Figure 18] It is a longitudinal sectional view of the low melting point material discharge structure according to the sixth embodiment. [Figure 19] It is a plan view of the low melting point material discharge structure according to the sixth embodiment. [Figure 20] It is a longitudinal sectional view after spacer melting of the low melting point material discharge structure according to the sixth embodiment. [Figure 21] It is a longitudinal sectional view of the low melting point material discharge structure according to the seventh embodiment. [Figure 22] It is a plan view of the low melting point material discharge structure according to the seventh embodiment. [Figure 23] It is a longitudinal sectional view after spacer melting of the low melting point material discharge structure according to the seventh embodiment.

Embodiments for Carrying Out the Invention

[0008] (First Embodiment) The first embodiment of the present invention will be described with reference to FIGS. 1-5. The low-melting-point material discharge structure (hereinafter referred to as the low-melting-point material discharge structure) 100A of this embodiment is applied to the battery case of a battery pack that is mounted on an electric vehicle that uses only a motor as a driving source, such as an electric vehicle, a hybrid vehicle, or a plug-in hybrid vehicle that can be externally charged or externally powered, and supplies power to the motor.

[0009] As shown in Figure 1, the battery pack consists of a battery case 10, a battery pack (not shown) comprising multiple battery modules housed in the 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 modules, and the like. The battery case 10 is made of steel and includes a battery tray 12 with an open top and a battery cover (not shown) that closes the top of the battery tray 12. The battery tray 12 comprises a bottom wall 1202 and peripheral walls (not shown) that rise from around the bottom wall 1202. The bottom wall 1202 houses a battery pack, a control device, a DC / DC converter, a cooling device, and the like (all not shown).

[0010] In this embodiment, the center of the bottom wall 1202 is the lowest point. During the roasting of the battery pack, various components made from low-melting-point materials with a melting point lower than the roasting temperature, such as cooling fins for electrical components located inside the battery pack case, brackets for fixing battery cells, and the battery module case, are melted. A discharge structure 100A for these molten low-melting-point materials is provided in the center of the bottom wall 1202. As shown in Figure 3, the low-melting-point material discharge structure 100A is composed of a fastening member 14, a fastening member insertion hole 16, a spacer 18, a blocking member 20, and a flow passage 22.

[0011] Various conventionally known fastening members such as bolts and steel rivets can be used as the fastening member 14, and in this embodiment, a steel bolt is used as the fastening member 14. The fastening member 14 comprises a hexagonal head 1402 and a male threaded portion 1404 that protrudes from the lower surface of the head 1402 as a shaft portion. The fastening member insertion hole 16 is located in the center of the bottom wall 1202, which is a wall portion that makes up the battery case 10 of the battery pack. The center of the bottom wall 1202, where the fastening member insertion hole 16 is provided, is located at the lowest point of the bottom wall 1202. The fastening member 14 is inserted through the fastening member insertion hole 16 from the inside to the outside of the battery case 10. The inner diameter of the fastening member insertion hole 16 is larger than the outer diameter of the male threaded portion 1404 of the fastening member 14, and smaller than the circular area tangent to the six sides of the regular hexagon on the lower surface of the head 1402 of the fastening member 14. Furthermore, it is sized such that the fastening member 14 can be securely tightened by the head 1402, and as shown in Figure 5, an annular channel 24 is formed between the male threaded portion 1404 and the inner circumferential surface of the fastening member insertion hole 16 through which molten low-melting-point material can flow. As shown in Figures 1 and 2, the inner surface 1202A of the bottom wall 1202 located inside the battery case 10 is open (upward) toward the head 1402 side of the fastening member 14, and when viewed from above, a plurality of grooves 26 are formed therein, extending from the outside of the head 1402 of the fastening member 14 to the fastening member insertion hole 16.

[0012] As shown in Figure 3, the spacer 18 is positioned on the inner surface 1202A of the wall portion where the fastening member insertion hole 16 is located. Spacer 18 can be circular, rectangular, or polygonal in plan view. In this embodiment, the spacer 18 is disc-shaped, has a spacer fastening member insertion hole 28 formed in the center, and has a thickness T1. The inner diameter of the spacer fastening member insertion hole 28 is a normal bolt insertion hole with an inner diameter that is approximately 0.1 to 0.2 mm larger than the outer diameter of the male threaded portion 1404 of the fastening member 14. The spacer 18 is made of a low-melting-point material that melts during the roasting process for recycling the battery pack. In other words, the spacer 18 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 roasting of the battery pack, brackets for fixing battery cells, and cases for battery modules. In other words, the spacer 18 is made of a material with a lower melting point than the fastening member 14, the bottom wall 1202 (wall portion), and the closing member 20. Examples of such low-melting-point materials include aluminum alloys, rubber, and synthetic resins. In this embodiment, an aluminum alloy is used as the spacer 18. 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 18.

[0013] As shown in Figure 3, the closing member 20 is made of steel and is positioned on the outer surface 1202B of the bottom wall 1202 of the battery case 10 where the fastening member insertion hole 16 is located. The closing member 20 has a female threaded portion 2002 which serves as a hole for connecting the fastening member. The male threaded portion 1404 of the fastening member 14 is inserted through the spacer fastening member insertion hole 28 and the fastening member insertion hole 16 and screwed into the female threaded portion 2002, causing the spacer 18 to abut against the inner surface 1202A of the wall portion and the closing member 20 to abut against the outer surface 1202B of the wall portion around the fastening member insertion hole 16, thereby closing the fastening member insertion hole 16 with the closing member 20. If a rivet or the like is used as the fastening member 14, the tip of the shaft portion of the rivet protruding from the fastening member coupling hole (female threaded portion 2002) is crushed, and the rivet is coupled to the closing member 20 via the fastening member coupling hole (female threaded portion 2002). Furthermore, a sealing member 30 is interposed between the closing member 20 and the outer surface 1202B of the wall portion around the fastening member insertion hole 16, surrounding the fastening member insertion hole 16. Note that the sealing member 30 is optional.

[0014] In this embodiment, a spacer 18 is placed on the inner surface 1202A of the bottom wall 1202 at the location where the fastening member insertion hole 16 is located, and a closing member 20 is placed on the outer surface 1202B of the bottom wall 1202 so as to cover the fastening member insertion hole 16. The male threaded portion 1404 of the fastening member 14 is inserted from the outside to the inside of the battery case 10 through the spacer fastening member insertion hole 28 and the fastening member insertion hole 16, the male threaded portion 1404 is connected to the female threaded portion 2002, and the closing member 20 is in contact with the outer surface 1202B of the wall. As a result, the spacer 18 is sandwiched between the head 1402 and the inner surface 1202A of the fastening member 14, and the fastening member insertion hole 16 is closed by the closing member 20.

[0015] Next, I will explain the effects and benefits. During the recycling of the battery pack, the battery pack is roasted, and this roasting process melts the spacer 18. When the spacer 18 melts, as shown in Figures 3 and 5, the closing member 20 and the fastening member 14 fall due to their own weight, and the lower surface of the head 1402 of the fastening member 14 comes into contact with the inner surface of the bottom wall 1202 around the fastening member insertion hole 16. Then, as shown in Figures 4 and 5, a flow passage 22 is formed between the lower surface of the head portion 1402 and the inner surface 1202A of the wall portion, extending from the outside of the head portion 1402 to the annular flow path 24, with multiple grooves 26 forming the passage. Furthermore, the fall of the fastening member 14 causes the closure member 20 to be located away from the outer surface of the bottom wall 1202, opening the lower end of the annular flow path 24 located at the lowest point 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 within the battery case 10, travel from the flow passage 22 to the annular flow path 24 together with the molten spacer 18, and then flow out downward from the lower end of the annular flow path 24. According to this embodiment, when recycling the battery pack, low-melting-point materials with a melting point lower than the roasting temperature, such as aluminum alloy, can be melted and discharged to the outside of the battery case 10 through the fastening member insertion hole 16, which is advantageous for easily recovering rare metals. In this embodiment, the case in which one fastening member insertion hole 16 is provided has been described, but it is also possible to provide multiple fastening member insertion holes 16 and provide multiple fastening members 14, spacers 18, and closing members 20 corresponding to the number of fastening member insertion holes 16. Furthermore, it is optional to provide multiple fastening member insertion holes 16, multiple fastening members 14 and spacers 18 corresponding to the number of fastening member insertion holes 16, and one closing member 20 large enough to cover the multiple fastening member insertion holes 16.

[0016] (Second Embodiment) Next, with reference to Figures 6 and 7, a discharge structure 100B for low-melting-point material according to the second embodiment will be described. In the second embodiment, the flow passage 22 differs from that in the first embodiment. In the following description of the embodiments, the same reference numerals are used for the same parts and components as in the first embodiment, and their descriptions are omitted or simplified. The description will focus on the parts that differ from the first embodiment. As shown in Figures 6 and 7, in the second embodiment, multiple grooves 32 are provided on the lower surface of the head 1402 of the fastening member 14, opening outwards from the outer circumference of the head 1402 and extending to the inner surface 1202A of the bottom wall 1202 of the battery case 10, at intervals in the circumferential direction of the male threaded portion 1404. Unlike the first embodiment, multiple grooves 26 leading to the fastening member insertion hole 16 are not formed on the inner surface of the bottom wall 1202.

[0017] As shown in Figure 7(A), in the second embodiment, similar to the first embodiment, the spacer 18 is placed on the inner surface 1202A of the central wall portion of the bottom wall 1202, the male threaded portion 1404 of the fastening member 14 is inserted through the spacer fastening member insertion hole 28 of the spacer 18, the closing member 20 is screwed onto the male threaded portion 1404, the fastening member insertion hole 16 is closed by the closing member 20 via the sealing member 30, and the spacer 18 is sandwiched between the head 1402 of the fastening member 14 and the inner surface 1202A of the wall portion. As shown in Figure 7(B), when the spacer 18 melts, the closing member 20 and the fastening member 14 fall due to their own weight, and the lower surface of the head 1402 of the fastening member 14 comes into contact with the inner surface of the bottom wall 1202 surrounding the fastening member insertion hole 16. Then, a flow passage 22 is formed between the lower surface of the head portion 1402 and the inner surface 1202A of the wall portion, extending from the outside of the head portion 1402 to the annular flow path 24, with multiple grooves 32 forming the passage. Furthermore, the fall of the fastening member 14 causes the closure member 20 to be located away from the outer surface of the bottom wall 1202, opening the lower end of the annular flow path 24 located at the lowest point of the bottom wall 1202. In the battery case 10, the low-melting-point material, which has a melting point lower than the roasting temperature, travels from the flow passage 22 to the annular flow path 24 together with the molten spacer 18, and flows out downward from the lower end of the annular flow path 24. This second embodiment also produces the same effects as the first embodiment.

[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 8-10. In the third embodiment, the shape of the spacer 18 differs from that of the first embodiment. As shown in Figures 8 and 9, the spacer 18 comprises a spacer body 18A positioned on the inner surface 1202A of the bottom wall 1202 where the fastening member insertion hole 16 is located, and a spacer cylindrical portion 18B protruding from the spacer body 18A 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 28 is formed through the spacer body 18A to the spacer cylindrical portion 18B, through which a male threaded portion 1404 is inserted. The inner diameter of the spacer fastening member insertion hole 28 is the same as in the first embodiment, and is a normal fastening member insertion hole having an inner diameter that is about 0.1 to 0.2 mm larger than the outer diameter of the male threaded portion 1404 of the fastening member 14. In the third embodiment, the spacer body 18A is placed on the inner surface 1202A of the wall portion, the spacer cylindrical portion 18B is inserted into the fastening member insertion hole 16, and the male threaded portion 1404 of the fastening member 14 is inserted through the spacer fastening member insertion hole 28 of the spacer body 18A and the spacer cylindrical portion 18B. Then, the closing member 20 is screwed onto the male threaded portion 1404, and the fastening member insertion hole 16 is closed by the closing member 20 via the sealing member 30, and the spacer 18 is sandwiched between the head 1402 of the fastening member 14 and the inner surface 1202A of the wall portion.

[0019] As shown in Figure 10, when the spacer 18 melts during roasting, the closing member 20 and the fastening member 14 fall due to their own weight, and the lower surface of the head 1402 of the fastening member 14 comes into contact with the inner surface of the bottom wall 1202 around the fastening member insertion hole 16. Then, between the lower surface of the head portion 1402 and the inner surface 1202A of the wall portion, a flow passage 22 is formed by multiple grooves 26, extending from the outside of the head portion 1402 to the annular flow path 24. Furthermore, the fall of the fastening member 14 causes the closure member 20 to be located away from the outer surface of the bottom wall 1202, opening the lower end of the annular flow path 24 located at the lowest point of the bottom wall 1202. In the battery case 10, the low-melting-point material, which has a melting point lower than the roasting temperature, travels from the flow passage 22 to the annular flow path 24 together with the molten spacer 18, and flows out downward from the lower end of the annular flow path 24.

[0020] This third embodiment also provides the same effects as the first embodiment, as well as the following effects. Similar to the first embodiment, the inner diameter of the fastening member insertion hole 16 is larger than the outer diameter of the male threaded portion 1404 of the fastening member 14, and smaller than the circle tangent to the six sides of the regular hexagon on the lower surface of the head 1402 of the fastening member 14. Furthermore, it is sized such that the fastening member 14 can be securely tightened by the head 1402, and an annular channel 24 is formed between the male threaded portion 1404 and the inner circumferential surface of the fastening member insertion hole 16 through which molten low-melting-point material can flow. In other words, the inner diameter of the fastening member insertion hole 16 is larger than that of a normal bolt insertion hole, which has an inner diameter that is about 0.1 to 0.2 mm larger than the outer diameter of the male threaded portion 1404 of the fastening member 14, thereby ensuring a large cross-sectional area of ​​the annular flow path 24. Therefore, in order to ensure a large tightening force by the fastening member 14 when the male threaded portion 1404 of the fastening member 14 is inserted through the fastening member insertion hole 16, it is preferable to position the male threaded portion 1404 of the fastening member 14 in the center of the fastening member insertion hole 16, which has a large inner diameter. As in the third embodiment, if a spacer fastening member insertion hole 28 with an inner diameter similar to that of a normal fastening member insertion hole is provided in the spacer cylinder portion 18B, the male threaded portion 1404 can be easily positioned in the center of the fastening member insertion hole 16 by inserting the male threaded portion 1404 through the spacer fastening member insertion hole 28. Therefore, it is advantageous to ensure a large tightening force by the fastening member 14 and to reliably close the fastening member insertion hole 16 by the closing member 20. Furthermore, forming the outer diameter of the spacer cylinder portion 18B 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 18B into the fastening member insertion hole 16 when positioning the spacer body 18A on the inner surface 1202A of the bottom wall 1202, is advantageous in ensuring that the fastening member insertion hole 16 is properly closed.

[0021] (Fourth embodiment) Next, a discharge structure 100D for low-melting-point material according to the fourth embodiment will be described with reference to Figures 11-13. The fourth to sixth embodiments described below differ from the first embodiment in that the fastening member 14 is inserted from the outside to the inside of the battery case 10. As shown in Figures 11 and 12, the discharge structure 100D of the low-melting-point material according to the fourth embodiment is composed of a fastening member 14, a locking member 34, a fastening member insertion hole 16, a spacer 18, and a flow passage 22.

[0022] The fastening member 14 is made of steel and has a hexagonal head 1402 and a male threaded portion 1404 that protrudes from the lower surface of the head 1402 as a shaft. The fastening member insertion hole 16 is located in the center of the bottom wall 1202, which is a wall portion that makes up the steel battery case 10 of the battery pack. The fastening member 14 is inserted through the fastening member insertion hole 16 from the outside to the inside of the battery case 10. The inner diameter of the fastening member insertion hole 16 is the same as in the first embodiment and is formed to be larger than that of a normal fastening member insertion hole. The inner surface 1202A of the bottom wall 1202 is open upwards, and when viewed from above, it has multiple grooves 26 that extend from the outside of the locking member 34 (described later) to the fastening member insertion hole 16 (annular flow path 24).

[0023] The spacer 18 is positioned on the inner surface 1202A of the central wall portion of the bottom wall 1202 where the fastening member insertion hole 16 is located. Spacer 18 can be circular, rectangular, or polygonal in plan view. In this embodiment, the spacer 18 is a circular plate shape, has a spacer fastening member insertion hole 28 in the center, has a thickness T1, and is sized to cover a plurality of grooves 26. The spacer fastening member insertion hole 28 is formed with the same inner diameter as a normal bolt insertion hole, similar to the first embodiment. The spacer 18 is made of a low-melting-point material that melts during the roasting process for recycling the battery pack, similar to the first embodiment, and is made of a material with a lower melting point than the fastening member 14 and the bottom wall 1202 (wall portion), and is made of an aluminum alloy. The locking member 34 is made of steel and has a female threaded portion 3402 as a fastening member connection hole that screws into a male threaded portion 1404 protruding from a spacer fastening member insertion hole 28 inside the battery case 10, and sandwiches the spacer 18 between itself and the inner surface 1202A of the wall portion.

[0024] As shown in Figures 11 and 12, in the fourth embodiment, a spacer 18 is placed on the inner surface 1202A of the wall portion where the fastening member insertion hole 16 is located, a locking member 34 is placed on the spacer 18, and the male threaded portion 1404 of the fastening member 14 is inserted from outside the battery case 10 into the fastening member insertion hole 16 and the spacer fastening member insertion hole 28. The male threaded portion 1404 is then screwed into the female threaded portion 3402, the spacer 18 is sandwiched between the closing member 20 and the inner surface 1202A of the wall portion, the lower surface of the head 1402 of the fastening member 14 abuts against the outer surface 1202B of the wall portion surrounding the fastening member insertion hole 16, and the fastening member insertion hole 16 is closed by the lower surface of the head 1402 of the fastening member 14. Furthermore, if a rivet or the like is used as the fastening member 14, the tip of the rivet shaft protruding from the fastening member connection hole (female threaded portion 3402) is crushed, and the rivet is connected to the locking member 34 via the fastening member connection hole (female threaded portion 3402).

[0025] As shown in Figure 13, when the spacer 18 melts during roasting, the locking member 34 and the fastening member 14 fall due to their own weight, and the locking member 34 comes into contact with the inner surface 1202A of the wall surrounding the fastening member insertion hole 16. Then, a flow passage 22 is formed between the locking member 34 and the inner surface 1202A of the wall portion, extending from the outside of the locking member 34 to the annular flow path 24, with multiple grooves 26 forming the passage. Furthermore, as the fastening member 14 falls, the lower surface of the head 1402 of the fastening member 14 is positioned below the outer surface 1202B of the wall, opening the lower end of the annular flow path 24 located at the lowest point 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 within the battery case 10, travel from the flow passage 22 to the annular flow path 24 together with the molten spacer 18, and then flow out downward from the lower end of the annular flow path 24. 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 case through the fastening member insertion hole 16, which is advantageous for easily recovering rare metals. In this embodiment, the case in which one fastening member insertion hole 16 is provided has been described, but it is also possible to provide multiple fastening member insertion holes 16 and provide multiple fastening members 14, spacers 18, and locking members 34 corresponding to the number of fastening member insertion holes 16. Furthermore, it is optional to provide multiple fastening member insertion holes 16, multiple fastening members 14 and spacers 18 corresponding to the number of fastening member insertion holes 16, and one locking member 34 large enough to cover the multiple fastening member insertion holes 16.

[0026] (Fifth embodiment) Next, a discharge structure 100E for low-melting-point material according to a fifth embodiment will be described with reference to Figures 14-17. In the fifth embodiment, the flow passage 22 differs from that in the fourth embodiment. As shown in Figures 15 and 16, in the fifth embodiment, as shown in Figure 14, multiple grooves 36 are provided on the lower surface of the locking member 34, opening outwards from the outer circumference of the locking member 34 and opening to the inner surface 1202A of the bottom wall 1202 of the battery case 10, and extending to the female threaded portion 3402 of the locking member 34, spaced apart in the circumferential direction of the female threaded portion. Unlike the fourth embodiment, multiple grooves 26 leading to the fastening member insertion hole 16 are not formed on the inner surface 1202A of the wall.

[0027] As shown in Figure 17, when the spacer 18 melts during roasting, the locking member 34 and the fastening member 14 fall due to their own weight, and the locking member 34 comes into contact with the inner surface 1202A of the wall surrounding the fastening member insertion hole 16. Then, a flow passage 22 is formed between the locking member 34 and the inner surface 1202A of the wall portion, extending from the outside of the locking member 34 to the annular flow path 24, with multiple grooves 36 forming the passage. Furthermore, as the fastening member 14 falls, the head 1402 of the fastening member 14 is positioned away from the outer surface of the bottom wall 1202, opening the lower end of the annular flow path 24. In the battery case 10, the low-melting-point material, which has a melting point lower than the roasting temperature, travels from the flow passage 22 to the annular flow path 24 together with the molten spacer 18, and flows out downward from the lower end of the annular flow path 24. This fifth embodiment also produces the same effects as the fourth embodiment.

[0028] (Sixth embodiment) Next, a discharge structure 100F for low-melting-point material according to the sixth embodiment will be described with reference to Figures 18-20. I will explain this. As shown in Figures 18-20, the sixth embodiment is the fourth embodiment with the addition of a washer 38. The washer 38 may be made of steel, or it may be formed from a low-melting-point material. In this embodiment, the washer 38 is made of steel and is placed on the outer surface 1202B of the bottom wall 1202 of the battery case 10. The male threaded portion 1404 of the fastening member 14 is inserted through the washer fastening member insertion hole 3802 of the washer 38, and the washer 38 is pressed against the outer surface 1202B of the wall surrounding the fastening member insertion hole 16 by the lower surface of the head 1402 of the fastening member 14, thereby closing the fastening member insertion hole 16 with the washer 38 and the head 1402 of the fastening member 14. Using such a washer 38 is advantageous in more reliably closing the fastening member insertion hole 16.

[0029] (Seventh Embodiment) Next, a discharge structure 100G for low-melting-point material according to the seventh embodiment will be described with reference to Figures 21-23. In the seventh embodiment, the shape of the spacer 18 differs from that of the sixth embodiment. The spacer 18 comprises a spacer body 18A positioned on the inner surface 1202A of the wall portion where the fastening member insertion hole 16 is located, and a spacer cylindrical portion 18B protruding from the spacer body 18A 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 28 is formed through the spacer body 18A to the spacer cylindrical portion 18B, through which a male threaded portion 1404 is inserted. In the seventh embodiment, the spacer body 18A is placed on the inner surface 1202A of the wall portion where the fastening member insertion hole 16 is located, and the spacer cylindrical portion 18B is inserted into the fastening member insertion hole 16. Then, the male threaded portion 1404 is inserted from the outside to the inside of the battery case 10 through the washer fastening member insertion hole 3802, the fastening member insertion hole 16, and the spacer fastening member insertion hole 28. The locking member 34 is then screwed onto the male threaded portion 1404, the spacer 18 is sandwiched between the locking member 34 and the inner surface of the wall portion 1202A, the washer 38 comes into contact with the outer surface of the wall portion 1202B around the fastening member insertion hole 16, and the fastening member insertion hole 16 is closed.

[0030] When the spacer 18 melts during roasting, the washer 38, locking member 34, and fastening member 14 fall due to their own weight, and the locking member 34 comes into contact with the inner surface 1202A of the wall surrounding the fastening member insertion hole 16. Then, a flow passage 22 is formed between the locking member 34 and the inner surface 1202A of the wall portion, extending from the outside of the locking member 34 to the annular flow path 24, with multiple grooves 26 forming the passage. Furthermore, the falling of the washer 38 and the fastening member 14 causes the heads 1402 of the washer 38 and the fastening member 14 to be located away from the outer surface of the bottom wall 1202, opening the lower end of the annular flow path 24. In the battery case 10, the low-melting-point material, which has a melting point lower than the roasting temperature, travels from the flow passage 22 to the annular flow path 24 together with the molten spacer 18, and flows out downward from the lower end of the annular flow path 24.

[0031] This seventh embodiment also provides the same effects as the sixth embodiment, as well as the following effects. As described above, the inner diameter of the fastening member insertion hole 16 is larger than that of a normal bolt insertion hole, which has an inner diameter that is about 0.1 to 0.2 mm larger than the outer diameter of the male threaded portion 1404 of the fastening member 14, thereby ensuring a large cross-sectional area of ​​the annular flow path 24. As in the seventh embodiment, if the spacer 18 is provided with a spacer cylindrical portion 18B that is inserted into the fastening member insertion hole 16, the male threaded portion 1404 can be easily positioned in the center of the fastening member insertion hole 16 by inserting the male threaded portion 1404 through the spacer fastening member insertion hole 28 of the spacer cylindrical portion 18B that is inserted into the fastening member insertion hole 16. Therefore, this is advantageous in ensuring a large tightening force by the fastening member 14 and in reliably closing the fastening member insertion hole 16 by the washer 38. Furthermore, forming the outer diameter of the spacer cylinder portion 18B 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 18B into the fastening member insertion hole 16 when positioning the spacer body 18A 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]

[0032] Discharge structure for 100A-100G 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 Spacers 18A Spacer Body 18B Spacer cylinder section 20 Closure member 2002 Female thread section 22 Distribution path 24 Circular channel 26 Multiple grooves 28 Spacer fastening member insertion hole 30 sealing member 32 Groove 34 Locking member 3402 Female thread section 36 Groove 38 Washers 3802 Fastening member insertion hole for washer

Claims

1. Fastening member insertion holes provided in the wall portion of the battery case of the battery pack, A spacer having a spacer fastening member insertion hole is disposed on the inner surface of the wall portion located inside the battery case at the location where the fastening member insertion hole is located, A closing member having a size that covers the fastening member insertion hole, positioned on the outer surface of the wall portion located outside the battery case, and having a fastening member connection hole formed therein, The fastening member comprises a head and a shaft portion protruding from the head, wherein the shaft portion extends from the inside to the outside of the battery case through a spacer fastening member insertion hole and is inserted into the fastening member insertion hole, and the shaft portion is connected to the closing member via a fastening member coupling hole, thereby causing the spacer to abut against the inner surface of the wall portion and the closing member to abut against the outer surface of the wall portion, thereby closing the fastening member insertion hole, The spacer is formed of a low-melting-point material with a lower melting point than the wall portion, the fastening member, and the closing member. The fastening member insertion hole is formed to a size that allows a flow path to be formed between the shaft portion and the inner circumferential surface of the fastening member insertion hole for the molten low-melting-point material, including the spacer. When the spacer has melted and the lower surface of the head of the fastening member is in contact with the inner surface of the wall surrounding the fastening member insertion hole, a flow passage is provided between the lower surface of the head and the inner surface of the wall, from the outside of the head to the flow path. A discharge structure for low-melting-point material that melts during the roasting of a battery pack, characterized by the above.

2. The spacer comprises a spacer body disposed on the inner surface of the wall portion 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 spacer fastening member insertion hole 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.

3. Fastening member insertion holes provided in the wall portion of the battery case of the battery pack, A spacer having a spacer fastening member insertion hole is disposed on the inner surface of the wall portion located inside the battery case at the location where the fastening member insertion hole is located, A locking member is disposed on the spacer, has a hole for fastening member connection, and can be locked to the inner surface of the wall portion surrounding the fastening member insertion hole, The fastening member 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 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 bringing the head into contact with the outer surface of the wall portion to close the fastening member insertion hole, The spacer is formed of a low-melting-point material with a lower melting point than the wall portion, the fastening member, and the locking member. The fastening member insertion hole is formed to a size that allows a flow path to be formed between the shaft portion and the inner circumferential surface of the fastening member insertion hole for the molten low-melting-point material, including the spacer. When the spacer has melted and the lower surface of the locking member is in contact with the inner surface of the wall surrounding the fastening member insertion hole, a flow passage is provided between the lower surface of the locking member and the inner surface of the wall, from the outside of the locking member to the flow path. A discharge structure for low-melting-point material that melts during the roasting of a battery pack, characterized by the above.

4. The spacer comprises a spacer body disposed on the inner surface of the wall portion 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 spacer fastening member insertion hole is formed extending from the spacer body to the spacer cylindrical portion. The discharge structure for low-melting-point material that is melted during roasting of the battery pack according to feature 3.

5. The shaft portion of the fastening member is inserted through the fastening member insertion hole and is sandwiched between the outer surface of the wall portion and the head of the fastening member around the fastening member insertion hole, and a washer is provided that closes the fastening member insertion hole together with the head of the fastening member. The discharge structure for low-melting-point material that is melted during roasting of the battery pack according to feature 3.

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