Pack housing and battery pack comprising same

Abstract

According to exemplary embodiments, a pack housing is provided. The pack housing comprises: a bottom plate; a cross beam on the bottom plate; a plurality of hybrid bolts, which are coupled to the cross beam and include different types of materials; and a plurality of bolts, which pass through the bottom plate and are fastened to respectively corresponding bolts from among the plurality of hybrid bolts.

Description

Pack housing and battery pack including the same

[0001] The present invention relates to a pack housing and a battery pack comprising the same. The present application claims the benefit of Korean application No. 10-2024-0162415, filed on November 14, 2024, which is incorporated herein by reference in its entirety.

[0002] Unlike primary batteries, secondary batteries can be charged and discharged multiple times. Secondary batteries are widely used as energy sources for various wireless devices such as handsets, laptops, and cordless vacuum cleaners. Recently, as the manufacturing cost per unit capacity of secondary batteries has decreased dramatically due to improved energy density and economies of scale, and as the driving range of BEVs (battery electric vehicles) has increased to a level equivalent to that of fuel vehicles, the primary use of secondary batteries is shifting from mobile devices to mobility.

[0003] The trend in the technological development of secondary batteries for mobility is the improvement of energy density and safety. The safety of secondary batteries for mobility is critical as it is directly related to the lives of passengers. The safety of secondary batteries can be achieved through mechanical robustness, the reliability of electrical insulation, and the delay of heat transfer in the event of a thermal runaway event.

[0004] The problem that the technical concept of the present invention aims to solve is to provide a pack housing having enhanced safety and a battery pack including the same.

[0005] According to exemplary embodiments of the present invention for solving the above-described problem, a pack housing is provided. The pack housing comprises: a bottom plate; a cross beam on the bottom plate; a plurality of hybrid bolts coupled to the cross beam and comprising heterogeneous materials; and a plurality of bolts penetrating the bottom plate and fastened to a corresponding one of the plurality of hybrid bolts.

[0006] Each of the above plurality of hybrid bolts includes a flange and a cylindrical part comprising a material different from the flange.

[0007] The melting point of the above flange is different from the melting point of the above cylinder.

[0008] The melting point of the above flange is lower than the melting point of the above cylinder.

[0009] The melting point of the above flange is different from the melting point of each of the above multiple bolts.

[0010] The melting point of the above flange is lower than the melting point of each of the above plurality of bolts.

[0011] The above flange contains resin, and the above cylindrical part contains metal.

[0012] The above flange is in contact with the lower surface of the above cross beam.

[0013] Each of the above plurality of bolts is fastened to the flange of the corresponding one among the plurality of hybrid bolts.

[0014] The above flange includes a recessed receiving portion in the extensional direction of the cylindrical portion.

[0015] The above pack housing further includes a plurality of nuts interposed between the bottom plate and the plurality of hybrid bolts.

[0016] Each of the above plurality of nuts is fastened to a corresponding one of the above plurality of bolts.

[0017] Each of the above plurality of nuts contacts the flange of the corresponding one among the above plurality of hybrid bolts.

[0018] The melting point of the above flange is different from the melting point of each of the above multiple nuts.

[0019] The melting point of the above flange is lower than the melting point of each of the above plurality of nuts.

[0020] According to exemplary embodiments of the present invention, when a thermal runaway event occurs in battery cell assemblies, the flanges of a plurality of hybrid bolts fastened to cross beams may melt. Accordingly, the bottom plate and the cross beams may be separated, thereby securing a space for venting between them, which may delay heat propagation and enhance the safety of the pack housing and the battery pack containing it.

[0021] The effects obtainable from the exemplary embodiments of the present invention are not limited to those mentioned above, and other unmentioned effects can be clearly derived and understood by those skilled in the art to which the exemplary embodiments of the present disclosure belong from the following description. That is, unintended effects resulting from the implementation of the exemplary embodiments of the present disclosure can also be derived by those skilled in the art from the exemplary embodiments of the present disclosure.

[0022] FIG. 1 is a plan view showing a battery pack according to exemplary embodiments.

[0023] Figure 2 is a cross-sectional view taken along the cutting line 1A-1A' of Figure 1.

[0024] Figure 3 is a cross-sectional view taken along the cutting line 1B-1B' of Figure 1.

[0025] FIG. 4 is a plan view showing a battery pack according to other exemplary embodiments.

[0026] FIG. 5 is a plan view showing a battery pack according to other exemplary embodiments.

[0027] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. Prior to this, terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted in a meaning and concept consistent with the technical spirit of the present invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention.

[0028] Therefore, the embodiments described in this specification and the configurations illustrated in the drawings are merely the most preferred embodiments of the present invention and do not represent all of the technical ideas of the present invention; thus, it should be understood that various equivalents and modifications that can replace them may exist at the time of filing this application.

[0029] In addition, in describing the present invention, if it is determined that a detailed description of related known components or functions may obscure the essence of the invention, such detailed description is omitted.

[0030] Since embodiments of the present invention are provided to more fully explain the invention to those skilled in the art, the shapes and sizes of the components in the drawings may be exaggerated, omitted, or schematically depicted for clearer explanation. Accordingly, the size or proportion of each component does not entirely reflect the actual size or proportion.

[0031]

[0032] (1st and 2nd embodiments)

[0033] FIG. 1 is a plan view showing a battery pack (100) according to exemplary embodiments.

[0034] Figure 2 is a cross-sectional view taken along the cutting line 1A-1A' of Figure 1.

[0035] Figure 3 is a cross-sectional view taken along the cutting line 1B-1B' of Figure 1.

[0036] Referring to FIGS. 1 to 3, the battery pack (100) may include a pack housing (110), a plurality of battery cell assemblies (120), and support structures (130). The battery pack (100) may be a final product mounted in an application such as a vehicle.

[0037] The pack housing (110) may provide a space for mounting a plurality of battery cell assemblies (120). The pack housing (110) may include a bottom plate (111), side walls (112), a center beam (113), cross beams (114), a plurality of hybrid bolts (115), a plurality of bolts (116), and a plurality of nuts (117).

[0038] Here, two directions substantially parallel to the mounting surface (111M) of the base plate (111) are defined as the X direction and the Y direction, and a direction substantially perpendicular to the mounting surface (111M) of the base plate (111) is defined as the Z direction. The X direction, the Y direction, and the Z direction may be substantially perpendicular to each other. The mounting surface (111M) may face a plurality of battery cell assemblies (120). The base plate (111) may have a flat plate shape. The base plate (111) may include metal.

[0039] Side walls (112) may be located at the edges of the bottom plate (111). Side walls (112) may be attached to the bottom plate (111). Side walls (112) may be fixed to the bottom plate (111) by methods such as bolting and welding. Side walls (112) may horizontally surround a plurality of battery cell assemblies (120). Side walls (112) may comprise metal.

[0040] The center beam (113) may extend in the X direction. The center beam (113) may be surrounded by side walls (112). The center beam (113) may be joined to the bottom plate (111). The center beam (113) may be fixed to the bottom plate (111) by either welding or bolting. The center beam (113) may comprise metal.

[0041] Each of the cross beams (114) may extend in the Y direction. The cross beams (114) may be surrounded by side walls (112). The cross beams (114) may be joined to the bottom plate (111). A center beam (113) may be located between the cross beams (114). Each of the cross beams (114) may contain metal.

[0042] Each of the cross beams (114) may include a plurality of holes (114H). Each of the cross beams (114) may have a solid structure. A plurality of holes (114H) may be formed by processing the cross beams (114) with mechanical tooling. The plurality of holes (114H) may include screw threads. Each of the plurality of holes (114H) may extend from the lower surface (114L) of the cross beams (114). The lower surface (114L) may face the mounting surface (111M). Each of the plurality of holes (114H) may face the mounting surface (111M).

[0043] Multiple hybrid bolts (115) can be joined to corresponding cross beams (114). Multiple hybrid bolts (115) can be fastened to corresponding cross beams (114).

[0044] Each of the plurality of hybrid bolts (115) may include a flange (115F) and a cylindrical portion (115S). The width of the flange (115F) may differ from the width of the cylindrical portion (115S). The width of the flange (115F) may be greater than the width of the cylindrical portion (115S).

[0045] Here, the width of an element may be the width of the element in a direction parallel to the mounting surface (111M) of the base plate (111). For example, the width may be one of the length in the X direction, the length in the Y direction, and the length in a direction parallel to the mounting surface (111M) and oblique to the X direction and the Y direction, respectively.

[0046] Each of the plurality of hybrid bolts (115) may comprise a different material. The flange (115F) may comprise a material different from that of the cylindrical portion (115S). The flange (115F) may comprise a resin. The flange (115F) may comprise one of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polycarbonate, and polysulfone. The cylindrical portion (115S) may comprise a metal. The cylindrical portion (115S) may comprise one of steel and stainless steel.

[0047] The flange (115F) may contain a thermally meltable material. The melting point of the flange (115F) may differ from the melting point of the cylindrical part (115S). The melting point of the flange (115F) may be lower than the melting point of the cylindrical part (115S).

[0048] The melting point of the flange (115F) may be different from the melting point of the base plate (111). The melting point of the flange (115F) may be lower than the melting point of the base plate (111). The melting point of the flange (115F) may be different from the melting point of each of the cross beams (114). The melting point of the flange (115F) may be lower than the melting point of each of the cross beams (114).

[0049] The flange (115F) can be joined to the cylindrical portion (115S). The flange (115F) can be fixed to the cylindrical portion (115S) by heat fusion. The flange (115F) can also be fastened to the cylindrical portion (115S) by bolting.

[0050] Each flange (115F) of a plurality of hybrid bolts (115) may include a receiving portion (115FR) for fastening with a corresponding bolt among the plurality of bolts (116). The receiving portion (115FR) may be a part of the recessed flange (115F). The receiving portion (115FR) may include threads for fastening with a corresponding bolt among the plurality of bolts (116).

[0051] Each cylindrical portion (115S) of a plurality of hybrid bolts (115) may be located within a corresponding hole (114H). Each cylindrical portion (115S) of a plurality of hybrid bolts (115) may include a screw thread and may be fastened to a corresponding hole (114H).

[0052] The flange (115F) of each of the plurality of hybrid bolts (115) may be outside the plurality of holes (114H). The flange (115F) of each of the plurality of hybrid bolts (115) may be in contact with the lower surface (114L) of the corresponding cross beams (114). Unlike the illustration in FIGS. 2 and 3, the flange (115F) of each of the plurality of hybrid bolts (115) may be spaced apart from the lower surface (114L) of each of the cross beams (114).

[0053]

[0054] Each of the plurality of bolts (116) can penetrate the bottom plate (111). The bottom plate (111) may include a plurality of holes (111H). Each of the plurality of bolts (116) can pass through a corresponding of the plurality of holes (111H).

[0055] Each of the plurality of bolts (116) may comprise metal. Each of the plurality of bolts (116) may comprise either steel or stainless steel. The melting point of the flange (115F) may differ from the melting point of each of the plurality of bolts (116). The melting point of the flange (115F) may be lower than the melting point of each of the plurality of bolts (116).

[0056] Each of the plurality of bolts (116) can be fastened to a corresponding one of the plurality of hybrid bolts (115). Each of the plurality of bolts (116) may include a portion within the receiving portion (115FR) of the flange (115F) of the corresponding one of the plurality of hybrid bolts (115).

[0057] Each of the plurality of bolts (116) may include a flange (116F) and a cylindrical portion (116S). The width of the flange (116F) may differ from the width of the cylindrical portion (116S). The width of the flange (116F) may be greater than the width of the cylindrical portion (116S).

[0058] The flange (116F) may be in contact with the bottom surface (111B) of the base plate (111). The bottom surface (111B) of the base plate (111) may be opposite to the mounting surface (111M). The flange (116F) may be spaced apart from the mounting surface (111M).

[0059] The cylindrical portion (116S) may include a portion within a corresponding one of the plurality of holes (111H). The cylindrical portion (116S) may include a portion within a receiving portion (115FR) of a corresponding flange (115F) of the plurality of hybrid bolts (115).

[0060] A plurality of nuts (117) may be interposed between a plurality of hybrid bolts (115) and a base plate (111). Each of the plurality of nuts (117) may come into contact with a corresponding one of the plurality of hybrid bolts (115). Each of the plurality of nuts (117) may come into contact with a flange (115F) of a corresponding one of the plurality of hybrid bolts (115). Each of the plurality of nuts (117) may come into contact with the base plate (111).

[0061] Each of the plurality of nuts (117) can be coupled with a corresponding one of the plurality of bolts (116). Each of the plurality of nuts (117) can be fastened with a corresponding one of the plurality of bolts (116). Accordingly, by fastening the plurality of nuts (117) and the plurality of bolts (116), the plurality of nuts (117) and the plurality of bolts (116) can be fixed to the floor plate (111). Additionally, since the plurality of bolts (116) are fastened to a corresponding one of the plurality of hybrid bolts (115), each of the cross beams (114) can be fixed to the floor plate (111).

[0062] Each cylindrical portion (116S) of a plurality of bolts (116) may include a portion fastened to a corresponding one of a plurality of nuts (117). Each cylindrical portion (116S) of a plurality of bolts (116) may include a portion within a fastening hole of a plurality of nuts (117). Each of a plurality of nuts (117) may surround the cylindrical portion (116S) of a corresponding one of the plurality of bolts (116).

[0063] Each of the plurality of nuts (117) may comprise metal. Each of the plurality of nuts (117) may comprise either steel or stainless steel. The melting point of the flange (115F) may differ from the melting point of each of the plurality of nuts (117). The melting point of the flange (115F) may be lower than the melting point of each of the plurality of nuts (117).

[0064] In the event that a thermal runway occurs in an adjacent of a plurality of battery cell assemblies (120), at least some of the flanges (115F) of the plurality of hybrid bolts (115) may melt. Here, thermal runway is an uncontrollable positive feedback condition in which a temperature change in the plurality of battery cell assemblies (120) further accelerates the temperature change. The plurality of battery cell assemblies (120) in a thermal runway state exhibit a rapid temperature rise and emit a large amount of high-pressure gas and combustion residue. According to exemplary embodiments, in the event of a thermal runway, due to the melting of at least some of the flanges (115F) of the plurality of hybrid bolts (115), the bottom plate (111) and the cross beams (114) are separated, and venting through the space between the bottom plate (111) and the cross beams (114) is promoted, thereby delaying or preventing heat propagation and thereby enhancing the safety of the battery pack (100).

[0065] Support structures (130) can be coupled to cross beams (114). Support structures (130) can be fixed to cross beams (114). Multiple battery cell assemblies (120) can be supported by support structures (130).

[0066] The support structures (130) may include a mounting portion (131) that overlaps in the Z direction with a corresponding cross beam (114), a support portion (133) that overlaps in the Z direction with a corresponding battery cell assembly (120), and a connecting portion (135) that connects the mounting portion (131) and the support portion (133). The connecting portion (135) may be substantially perpendicular to the X direction.

[0067] The mounting portion (131) can be joined to the cross beams (114). The mounting portion (131) can be fixed to the cross beams (114) by either welding or bolting. The mounting portion (131) can be substantially perpendicular to the Z direction.

[0068] The support portion (133) may be closer to the bottom plate (111) than the mounting portion (131). The support portion (133) may support a corresponding one of the plurality of battery cell assemblies (120). The support portion (133) may include a plurality of venting holes (130H) that expose the lower portion of a corresponding one of the plurality of battery cell assemblies (120). The support portion (133) may be substantially perpendicular to the Z direction. The support portion (133) may be spaced apart from the bottom plate (111). The support portion (133) may be interposed between the bottom plate (111) and a corresponding one of the plurality of battery cell assemblies (120).

[0069] The center beam (113) and cross beams (114) can isolate multiple battery cell assemblies (120) from each other. The multiple battery cell assemblies (120) can be spaced apart in the Y direction with the center beam (113) in between. The center beam (113) can be interposed between the multiple battery cell assemblies (120). The multiple battery cell assemblies (120) can be spaced apart in the X direction with the cross beams (114) in between. The cross beams (114) can be interposed between the multiple battery cell assemblies (120).

[0070] In FIG. 1, the arrangement of multiple battery cell assemblies (120) can be described as a 3 * 2 arrangement. The arrangement of multiple battery cell assemblies (120) disclosed in FIG. 1 is a non-limiting example and does not limit the technical concept of the present invention in any sense. A person skilled in the art will be able to easily arrive at a plurality of battery cell assemblies (120) arranged in an M * N arrangement (where M and N are each integers greater than or equal to 2) based on what is described herein.

[0071] A plurality of battery cell assemblies (120) may be mounted on support structures (130). A plurality of battery cell assemblies (120) may be spaced apart from the bottom plate (111). Accordingly, a space for venting may be provided between the bottom plate (111) and the support structures (130). Each of the plurality of battery cell assemblies (120) may include a plurality of battery cells, a plurality of pads, and first and second integrated circuit assemblies.

[0072] Each of the plurality of battery cells may include an electrode assembly, an electrolyte, and a case. Each of the plurality of battery cells may be any one of a cylindrical battery cell, a prismatic battery cell, and a pouch-type battery cell. The electrode assembly of the cylindrical battery cell is embedded in a cylindrical metal can. The electrode assembly of the prismatic battery cell is embedded in a prismatic metal can. The electrode assembly of the pouch-type battery cell is embedded in a pouch case comprising an aluminum laminate sheet.

[0073] An electrode assembly includes an anode, a cathode, and a separator interposed between the anode and the cathode. A jelly roll type electrode assembly includes a wound structure of an anode, a cathode, and a separator interposed between them. A stack type electrode assembly includes a plurality of sequentially stacked anodes, a plurality of cathodes, and a plurality of separators interposed between them.

[0074] According to exemplary embodiments, a plurality of battery cells may form a plurality of banks. A plurality of banks may include one or more parallel-connected battery cells. A plurality of banks may be connected in series with each other. The number of battery cells included in each of the plurality of banks and the number of banks connected in series with each other may be determined according to the voltage and current to be output through each of the plurality of battery cell assemblies (120).

[0075] According to exemplary embodiments, a plurality of pads may comprise a compressible material. A plurality of pads may be interposed between a plurality of battery cells. A plurality of pads may absorb swelling of a plurality of battery cells. According to exemplary embodiments, a plurality of pads may be a thermal barrier.

[0076] The first integrated circuit assembly may include an insulating frame, an integrated circuit, busbars, wiring, and an insulating cover. The integrated circuit assembly may include physical and functional configurations for providing electrical connections between a plurality of battery cells, outputting the resulting voltage of the plurality of battery cells, and measuring the voltage (or current) of nodes within a circuit composed of the plurality of battery cells.

[0077] The insulating frame may include an insulating material such as plastic. The insulating frame may cover the front of multiple battery cells. The insulating frame may support integrated circuits, bus bars, and wiring.

[0078] The bus bars can be short-circuited to the positive leads of the battery cells of the first bank and the negative leads of one or more battery cells of the last bank. The bus bars can be welded to the positive leads of the battery cells of the first bank and the negative leads of one or more battery cells of the last bank. The resulting voltage of each of the multiple battery cells of the multiple battery cell assemblies (120) can be output through the bus bars. The bus bars can be fixed to an insulating frame.

[0079] The integrated circuit can be mounted on an insulating frame. Positive leads and negative leads welded to each other can form nodes within each of the plurality of battery cell assemblies (120). The integrated circuit can be configured to measure the voltage of the nodes through sensing plates and sensing bars.

[0080] The sensing bars may include a conductive material. The sensing bars may have a rod shape. The sensing bars may be short-circuited to the bus bars. The sensing bars may be coupled to the bus bars. Through the sensing bars, the voltage of the bus bars can be measured.

[0081] Each of the plurality of sensing plates may have a patch shape or a pad shape. The plurality of sensing plates may include a conductive material. The plurality of sensing plates may be short-circuited to corresponding positive leads and negative leads of the plurality of battery cells.

[0082] Each of the multiple sensing plates can be connected to an integrated circuit. Through the multiple sensing plates, the voltage of multiple nodes within the multiple battery cell assemblies (120) can be measured.

[0083] The insulating cover may include an insulating material such as plastic. The insulating cover may be fitted into an insulating frame. The insulating cover may cover integrated circuits and bus bars, and accordingly, the electrical elements of the first and second integrated circuit assemblies may be protected.

[0084] The second integrated circuit assembly may include an insulating frame, an integrated circuit, busbars, wiring, and an insulating cover. The second integrated circuit assembly is substantially identical to the first integrated circuit assembly except that it does not include busbars.

[0085] The battery pack (100) may further include leads coupled to the side walls (112) of the pack housing (110). The leads may cover elements mounted inside the battery pack (100), such as a plurality of battery cell assemblies (120) and electrical components. The leads may be secured to the pack housing (110) by mechanical coupling means, such as bolting.

[0086] The battery pack may further include exhaust devices coupled to the pack housing (110) or the lead. The pack housing (110) or the lead may include exhaust holes connected to the exhaust devices. In the event that a thermal runaway event occurs in a plurality of battery cell assemblies (120), the exhaust devices may be configured to delay thermal propagation by releasing high-temperature gas inside the battery pack (100) to the outside.

[0087] The battery pack (100) may further include a Battery Management System (BMS). The BMS may be configured to perform monitoring, balancing, and control of the battery pack (100). Monitoring of the battery pack (100) may include measuring the voltage and current of specific nodes within a plurality of battery cell assemblies (120) and measuring the temperature of set locations within the battery pack (100). The battery pack (100) may include measuring instruments for measuring the voltage, current, and temperature described above.

[0088] Balancing of the battery pack (100) is an operation that reduces deviations between multiple battery cell assemblies (120). Control of the battery pack (100) includes preventing overcharging, over-discharging, and overcurrent. Through monitoring, balancing, and control, the battery pack (100) can operate under optimal conditions, and accordingly, the shortening of the lifespan of each of the multiple battery cell assemblies (120) can be prevented.

[0089] The battery pack (100) may further include additional electrical components such as a cooling device, a Power Relay Assembly (PRA), and a safety plug. The cooling device may include a cooling fan. The cooling fan can prevent overheating of each of the multiple battery cell assemblies (120) by circulating air inside the battery pack (100). The PRA may be configured to supply or cut off power from the high-voltage battery to an external load (e.g., a vehicle motor). The PRA can protect the multiple battery cell assemblies (120) and the external load (e.g., a vehicle motor) by cutting off power supply to the external load (e.g., a vehicle motor) in situations where abnormal voltage occurs, such as a voltage surge.

[0090] The battery pack (100) may further include a plurality of interbusbars configured to electrically connect a plurality of battery cell assemblies (120). The plurality of battery cell assemblies (120) may be connected in series by the plurality of interbusbars. Accordingly, the battery pack (100) may be configured to output a high voltage to an external load (e.g., a motor of a vehicle).

[0091]

[0092] (3rd Example)

[0093] FIG. 4 is a plan view showing a battery pack (100') according to other exemplary embodiments.

[0094] Referring to FIG. 4, the battery pack (100') may include a pack housing (110'), a plurality of battery cell assemblies (120, see FIG. 1) and support structures (130). The battery pack (100') may be a final product mounted in an application such as a vehicle. Since the battery cell assemblies (120, see FIG. 1) and support structures (130) are substantially the same as those described with reference to FIG. 1 through 3, a redundant description thereof is omitted.

[0095] The pack housing (110') is substantially the same as described with reference to FIGS. 1 through 3, except for the cross beams (114'). In this example, a plurality of hybrid bolts (115) may be embedded in corresponding cross beams (114'). The cross beams (114') may include a plurality of holes (114H'). Each of the plurality of holes (114H') may include a first portion having a first width and a second portion having a second width. The second width may be larger than the first width.

[0096] In the first part of each of the plurality of holes (114H'), there may be a cylindrical portion (115S) of a corresponding one of the plurality of hybrid bolts (115). In the second part of each of the plurality of holes (114H'), there may be a flange (115F) of a corresponding one of the plurality of hybrid bolts (115). Each of the plurality of holes (114H') may include a cross section having a stepped shape. The lower surface (114L') of each of the cross beams (114') may come into contact with a corresponding one of the plurality of nuts (117).

[0097]

[0098] (Fourth Example)

[0099] FIG. 5 is a plan view showing a battery pack (100) according to other exemplary embodiments.

[0100] Referring to FIG. 5, the battery pack (100) may include a pack housing (110), a plurality of battery cell assemblies (120, see FIG. 1) and support structures (130). The battery pack (100) may be a final product mounted in an application such as a vehicle. Since the battery cell assemblies (120, see FIG. 1) and support structures (130) are substantially the same as those described with reference to FIG. 1 through 3, a redundant description thereof is omitted.

[0101] The pack housing (110) is substantially the same as described with reference to FIGS. 1 through 3, except for the cross beams (114). In this example, a plurality of hybrid bolts (115) may be embedded in corresponding cross beams (114). In this example, a plurality of nuts (117) may be embedded in corresponding cross beams (114).

[0102] The cross beams (114") may include a plurality of holes (114H"). Each of the plurality of holes (114H") may include a first portion having a first width, a second portion having a second width, and a third portion having a third width. The second width may be larger than the first width. The third width may be larger than the second width.

[0103] In the first part of the plurality of holes (114H"), there may be a cylindrical portion (115S) of a corresponding one of the plurality of hybrid bolts (115). In the second part of the plurality of holes (114H"), there may be a flange (115F) of a corresponding one of the plurality of hybrid bolts (115). In the third part of the plurality of holes (114H"), there may be a corresponding one of the plurality of nuts (117). Each of the plurality of holes (114H") may include a cross section having a stepped shape. The lower surface (114L") of each of the cross beams (114") may be in contact with the mounting surface (111M) of the base plate (111).

[0104]

[0105] The present invention has been described in more detail above through drawings and embodiments. However, the configurations described in the drawings or embodiments described in this specification are merely one embodiment of the present invention and do not represent all technical concepts of the present invention; therefore, it should be understood that various equivalents and modifications that can replace them may exist at the time of filing this application.

Claims

1. Base plate; Cross beam on the floor plate above; and A plurality of hybrid bolts coupled to the above cross beam and comprising heterogeneous materials; and A pack housing comprising a plurality of bolts penetrating the floor plate and each fastened to a corresponding one of the plurality of hybrid bolts.

2. In Paragraph 1, A pack housing characterized in that each of the plurality of hybrid bolts comprises a flange and a cylindrical portion having a material different from that of the flange.

3. In Paragraph 2, Pack housing characterized in that the melting point of the above flange is different from the melting point of the above cylindrical part.

4. In Paragraph 2, Pack housing characterized by the melting point of the above flange being lower than the melting point of the above cylindrical part.

5. In Paragraph 2, Pack housing characterized in that the melting point of the above flange is different from the melting point of each of the above plurality of bolts.

6. In Paragraph 2, Pack housing characterized in that the melting point of the above flange is lower than the melting point of each of the above plurality of bolts.

7. In Paragraph 2, Pack housing characterized in that the above flange comprises resin and the above cylindrical part comprises metal.

8. In Paragraph 2, Pack housing characterized by the above flange contacting the lower surface of the above cross beam.

9. In Paragraph 2, A pack housing characterized in that each of the plurality of bolts is fastened to the flange of a corresponding one among the plurality of hybrid bolts.

10. In Paragraph 2, A pack housing characterized in that the above flange includes a recessed receiving portion in the extension direction of the above cylindrical portion.

11. In Paragraph 2, A pack housing further comprising a plurality of nuts interposed between the above-mentioned bottom plate and the plurality of hybrid bolts.

12. In Paragraph 11, A pack housing characterized in that each of the plurality of nuts is fastened to a corresponding one of the plurality of bolts.

13. In Paragraph 11, A pack housing characterized in that each of the plurality of nuts contacts the flange of the corresponding one among the plurality of hybrid bolts.

14. In Paragraph 11, Pack housing characterized in that the melting point of the above flange is different from the melting point of each of the above plurality of nuts.

15. In Paragraph 11, Pack housing characterized in that the melting point of the above flange is lower than the melting point of each of the above plurality of nuts.

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