Battery pack with improved fastening structure and vehicle including the same

Abstract

A battery pack according to an embodiment of the present invention includes: a module stack in which a plurality of battery modules are stacked; a battery pack cover having a lower cover and an upper cover, the lower cover supporting the module stack from below, the upper cover being coupled to the lower cover from an upper portion of the module stack structure; a plurality of weld nuts fixed to a lower surface of the lower cover; and a plurality of fastening bolts fastened to the weld nuts after passing through the battery pack cover and the module stack.

Description

Technical Field

[0001] The present disclosure relates to a battery pack having an improved fastening structure and a vehicle including the battery pack. More particularly, the present disclosure relates to a battery pack and a vehicle including the battery pack, which can increase connection reliability, reduce costs, and prevent moisture from penetrating through a fastening portion at the outer side of the battery pack cover by fastening a module stack and a battery pack cover together using bolts.

[0002] This application claims priority from Korean Patent Application No. 10-2020-0000994 filed in Korea on January 3, 2020, the disclosure of which is incorporated herein by reference. Background Art

[0003] Secondary batteries, which are easily applicable to various product groups and have electrical characteristics such as high energy density, are not only commonly used in portable devices, but also in electric vehicles (EVs) or hybrid electric vehicles (HEVs) driven by electric drive sources. Because secondary batteries do not produce byproducts due to the use of energy and have the main advantage of significantly reducing the use of fossil fuels, such secondary batteries have attracted attention as a new energy source for improving environmental friendliness and energy efficiency.

[0004] The types of secondary batteries currently widely used in this field include lithium-ion batteries, lithium polymer batteries, nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, etc. The operating voltage of such a unit secondary battery cell, that is, a unit battery cell, is about 2.5V to 4.5V. Therefore, if a higher output voltage is required, a battery pack can be constructed by connecting multiple battery cells in series. In addition, a battery pack can be constructed by connecting multiple battery cells in parallel according to the charge / discharge capacity required by the battery pack. Accordingly, the number of battery cells included in the battery pack can be set differently according to the required output voltage or charge / discharge capacity.

[0005] Meanwhile, when constructing a battery pack by connecting a plurality of battery cells in series / parallel, generally, a battery module including the plurality of battery cells is first constructed, and a module stack formed by stacking a plurality of such battery modules is housed in a pack housing to construct the battery pack.

[0006] Accordingly, there is a need to reduce component costs and improve structural reliability by developing a battery pack having a structure that can simplify connections between a plurality of battery modules and between a module stack and a pack cover as much as possible. Summary of the Invention

[0007] Technical issues

[0008] The present disclosure is designed to solve the problems of the related art, and thus aims to reduce parts, simplify processes, increase energy density, and improve structural reliability by allowing fastening between multiple battery modules and between a module stack formed by stacking multiple battery modules and a battery pack cover to be made as simple as possible.

[0009] However, the technical problems to be solved by the present disclosure are not limited to the above, and those skilled in the art will clearly understand other problems not mentioned herein based on the following description.

[0010] Technical Solution

[0011] In one aspect of the present disclosure, a battery pack is provided, comprising: a module stack in which a plurality of battery modules are stacked; a battery pack cover having a lower cover and an upper cover, the lower cover being configured to support the module stack at a lower side of the module stack, the upper cover being coupled to the lower cover from an upper side of the module stack; a plurality of weld nuts fixed to a lower surface of the lower cover; and a plurality of fastening bolts passing through the battery pack cover and the module stack and fastened to the weld nuts.

[0012] The lower housing may include: a lower housing body configured to provide an accommodation space for the module stack; and an airtight plate assembly attached to a lower surface of the lower housing body and configured to provide an accommodation space for the weld nut.

[0013] The airtight plate assembly may include a gasket configured to cover the weld nut; and an airtight plate configured to press the gasket and attached to a lower surface of the lower housing.

[0014] The airtight plate may have a double-step structure provided with a space for accommodating the gasket and a space for accommodating the weld nut.

[0015] An attaching groove may be formed at a lower surface of the lower housing body such that the airtight plate assembly is attached to the attaching groove.

[0016] The depth of the attachment groove may be equal to or greater than the height of the step of the airtight plate.

[0017] The head of the fastening bolt may be covered with a sealing member.

[0018] The battery module may include: a unit module stack formed by coupling a plurality of unit modules; and a BMS assembly coupled to one longitudinal side of the unit module stack.

[0019] The BMS assembly may have a plurality of first fastening holes formed along a height direction of the BMS assembly, and the unit module may have: a plurality of second fastening holes formed at one longitudinal side of the unit module; and a plurality of third fastening holes formed at the other longitudinal side of the unit module.

[0020] Among the plurality of fastening bolts, the first fastening bolt may simultaneously pass through the first and second fastening holes overlapping each other, and the second fastening bolt may simultaneously pass through the second and third fastening holes overlapping each other, so that the battery pack cover, the BMS assembly, and the unit module stack are coupled at one time.

[0021] The unit module may have a structure in which a plurality of battery cell groups are arranged along a width direction of the unit module, each battery cell group having a plurality of battery cells arranged in a longitudinal direction of the unit cell, and the third fastening hole may be formed in a dead zone generated when adjacent battery cell groups are placed to be shifted from each other.

[0022] Meanwhile, in another aspect of the present disclosure, a vehicle is also provided, which includes the battery pack according to the embodiment of the present disclosure.

[0023] Beneficial effects

[0024] According to the embodiments of the present disclosure, it is possible to reduce components, simplify processes, increase energy density, and improve structural reliability by allowing fastening between multiple battery modules and between a module stack formed by stacking multiple battery modules and a pack cover to be made as simple as possible. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings illustrate preferred embodiments of the present disclosure and, together with the foregoing disclosure, serve to provide further understanding of the technical features of the present disclosure. Therefore, the present disclosure is not to be construed as being limited to the accompanying drawings.

[0026] Figure 1 is a perspective view showing a battery pack according to an embodiment of the present disclosure.

[0027] Figure 2 It shows Figure 1 Exploded perspective view of the battery pack.

[0028] Figure 3 is clearly shown to be applied to Figure 1 is a view of the lower surface of the battery pack housing of the battery pack shown in .

[0029] Figure 4 It shows Figure 3 A view of the internal structure of area A.

[0030] Figure 5 is shown to be applied to Figure 1 Figure 2 shows a view of a battery module of a battery pack with the module cover removed.

[0031] Figure 6 It is clearly shown Figure 5 FIG. 1 is a view of a battery cell housed in a battery cell housing in a battery module.

[0032] Figure 7 is an exploded perspective view showing a lower cover employed at a battery pack cover applied to the present disclosure.

[0033] Figure 8 It is along Figure 1 A cross-sectional view taken along line XX.

[0034] Figure 9 It shows Figure 8 Magnified view of area B.

[0035] Figure 10 is a view showing a fastening bolt applied to the present disclosure. DETAILED DESCRIPTION

[0036] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Before the description, it should be understood that the terms used in the specification and the appended claims should not be interpreted as limited to the general and dictionary meanings, but should be interpreted based on the corresponding meanings and concepts of the technical aspects of the present disclosure based on the principle of allowing the inventors to appropriately define the terms for the best interpretation. Therefore, the descriptions provided herein are only preferred examples for illustrative purposes only and are not intended to limit the scope of the present disclosure. Therefore, it should be understood that other equivalents and modifications can be made thereto without departing from the scope of the present disclosure.

[0037] First, refer to Figures 1 to 4 A schematic structure of a battery pack 1 according to an embodiment of the present disclosure is described.

[0038] refer to Figures 1 to 4 The battery pack 1 according to an embodiment of the present disclosure includes a module stack M, a pack cover 200 , a plurality of fastening bolts 300 , and a plurality of welding nuts 400 .

[0039] like Figure 2 As shown in FIG, the module stack M has a form in which a plurality of battery modules 100 are stacked. Figure 5 and Figure 6 A detailed structure of each battery module 100 is described.

[0040] like Figure 2As shown in FIG, the battery pack housing 200 includes a lower housing 210 for supporting the lower portion of the module stack M and an upper housing 220 for covering the upper portion of the module stack M and coupled to the lower housing 210. The lower housing 210 has a special structure on its lower surface, and the special structure of the lower housing 210 will be described in detail later.

[0041] like Figure 1 and Figure 2 As shown in FIG, the plurality of fastening bolts 300 have a long bolt shape and may sequentially pass through the upper housing 220 , the module stack M, and the lower housing 210 , such that the module stack M is fixed to the pack housing 200 .

[0042] like Figure 4 As shown in FIG, the weld nut 400 is attached to the bottom surface of the lower housing 210 by welding (see FIG. Figure 2 and Figure 3 The weld nut 400 is attached at a position corresponding to the through-hole formed in the bottom surface of the lower housing 210, thereby coupling with the fastening bolt 300. Furthermore, the weld nut 400 is located inside the gasket 212a and the airtight plate 212b provided to the lower housing 210. As described above, the weld nut 400 is located inside the gasket 212a and the airtight plate 212b, thereby preventing foreign matter or moisture from penetrating into the interior of the battery pack housing 200 through the through-hole formed in the lower housing 210, thereby shortening the life of the battery pack 1 or degrading the performance of the battery pack 1.

[0043] Next, we will Figure 2 Reference together Figure 5 and Figure 6 The battery module 100 applied to the module stack M of the present disclosure will be described in detail.

[0044] Figure 5 The battery module 100 shown in FIG is in the following state: the outer cover is removed, that is, Figure 2 The module housing of the battery module 100 shown in FIG. Figure 5 The battery module 100 shown in FIG. Figure 2 The battery modules 100 shown in FIG. 1 are different in the presence or absence of the module cover, but the same reference numerals are applied for convenience of explanation.

[0045] refer to Figure 5 and Figure 6The battery module 100 includes: a unit module stack 110 formed by connecting a plurality of unit modules 111; and a BMS assembly 120 connected to the unit module stack 110 in the longitudinal direction ( Figure 5 At one end in the direction parallel to the X-axis).

[0046] The unit module 111 includes a battery cell housing 111a and a plurality of battery cells 111b. The battery cells 111b are accommodated in the battery cell housing 111a and are electrically connected to each other. The battery cells 111b may be cylindrical, for example.

[0047] The BMS assembly 120 includes a plurality of BMSs (Battery Management Systems) 121 and a BMS frame 122 for surrounding and fixing the BMSs 121. Each BMS 121 is electrically connected to the unit module 111 and can function as a slave BMS. That is, the plurality of BMSs 121 can be connected to a single master BMS (not shown).

[0048] The battery module 100 has a plurality of fastening holes H1 to H3, fastening bolts 300 (see Figure 1 and Figure 2 ) can pass through the plurality of fastening holes H1 to H3. Specifically, the BMS frame 122 includes a plurality of first fastening holes H1, and the plurality of first fastening holes H1 are arranged along the width direction of the battery module 100 ( Figure 5 In addition, the unit module 111 has a plurality of second fastening holes H2, which are formed in the longitudinal direction ( Figure 5 The unit module 111 is located at one end of the unit module 111 along the width direction ( Figure 5 The second fastening holes H1 and the second fastening holes H2 are formed in the battery cell cover 111a of the unit module 111. That is, the second fastening holes H2 are formed in the remaining space of the battery cell cover 111a except for the accommodation space for the battery cell 111b. When the unit module stack 110 and the BMS assembly 120 are assembled to form the battery module 100, the first fastening holes H1 and the second fastening holes H2 overlap with each other. Therefore, the fastening bolts 300 pass through the first fastening holes H1 and the second fastening holes H2 at the same time, so that the unit module stack 110, the BMS assembly 120 and the battery pack cover 200 are coupled at one time.

[0049] In addition, the unit module 111 has a plurality of third fastening holes H3 formed in the longitudinal direction ( Figure 5 The other end of the unit module 111 is located in the direction parallel to the X axis and along the width direction of the unit module 111 ( Figure 5 The second and third fastening holes H2 and H3 are spaced apart from each other (in a direction parallel to the Y-axis). The third fastening holes H3 are formed in the battery cell housing 111a of the unit module 111. That is, the third fastening holes H3 are formed in the remaining space of the battery cell housing 111a, excluding the space for accommodating the battery cells 111b. When the unit modules 111 are assembled to form the unit module stack 110, the second and third fastening holes H2 and H3 overlap. Therefore, the fastening bolts 300 pass through the second and third fastening holes H2 and H3 simultaneously, thereby coupling the unit module stack 110 and the battery pack housing 200 at once.

[0050] At the same time, reference Figure 6 , is formed in the longitudinal direction of the battery module 100 ( Figure 6 The third fastening hole H3 at one of the two sides (in the direction parallel to the X axis) is formed by utilizing a dead space generated when adjacent battery cell groups G are placed to be displaced from each other, and the side where the third fastening hole H3 is located is opposite to the side to which the BMS assembly 120 is connected. That is, the unit module 111 has a structure in which a plurality of battery cell groups G are arranged in the width direction ( Figure 6 In the direction parallel to the Y axis), each of the battery cell groups G has a longitudinal direction ( Figure 6 The plurality of battery cells 111b are arranged in a direction parallel to the X-axis in the direction of the battery cell group G, and the third fastening holes H3 are formed in a dead space generated when adjacent battery cell groups G are positioned so as to be displaced from each other. Since the third fastening holes H3 are formed using the dead space as described above, energy density loss due to the formation of the third fastening holes H3 can be prevented.

[0051] Next, along with Figure 4 Reference together Figures 7 to 10 , a fastening structure using the airtight plate assembly 212 , the fastening bolts 300 , and the welding nuts 400 applied to the battery pack 1 according to an embodiment of the present disclosure and the resulting effects of improving fastening and airtightness will be described in detail.

[0052] First, accompany Figure 4 Reference together Figures 7 to 10The lower housing 210 includes a lower housing body 211 and an airtight plate assembly 212. The airtight plate assembly 212 is inserted into an attachment groove 211a formed at a lower surface of the lower housing body 211 and fixed to an inner bottom surface of the attachment groove 211a by welding or the like.

[0053] The airtight plate assembly 212 includes a gasket 212a and an airtight plate 212b. The gasket 212a surrounds the periphery of the weld nut 400 attached to the lower surface of the lower housing body 211 by welding and is interposed between the weld nut 400 and the airtight plate 212b to prevent foreign matter or moisture from penetrating into the gap between the weld nut 400 and the bottom surface of the lower housing body 211. The airtight plate 212b covers the gasket 212a and weld nut 400 within the attachment groove 211a and is fixed to the bottom surface of the lower housing body 211 by welding or the like to primarily prevent the infiltration of foreign matter and / or moisture.

[0054] The airtight plate 212b compresses the gasket 212a and is attached to the lower surface of the lower housing 210, that is, to the bottom surface of the lower housing body 211. Furthermore, the airtight plate 212b may have a double-step structure, providing a space for accommodating the gasket 212a and a space for accommodating the weld nut 400. However, according to the double-step structure, the depth of the attachment groove 211a is preferably equal to or greater than the height of the airtight plate 212b. This is to prevent energy density loss caused by the formation of the airtight plate 212b.

[0055] At the same time, reference Figure 10 The fastening bolt 300 may have a sealing member S covering the surface of the head thereof to minimize the infiltration of foreign matter and / or moisture through the hole formed in the upper portion of the battery pack housing 200, i.e., the through-hole formed in the upper housing 220. The sealing member S may be made of an elastic material, such as a polyurethane material.

[0056] Because the battery pack 1 according to the embodiment of the present disclosure has a structure capable of fastening each component of the module stack M and the battery pack cover 200 together at one time by using the welding nut 400 that is pre-fixed to the battery pack cover 200 and the fastening bolt 300 that passes through the battery pack cover 200 and the module stack M and is fastened to the welding nut 400, it is possible to improve fastening reliability and reduce costs.

[0057] In addition, since the battery pack 1 according to an embodiment of the present disclosure has a structure that prevents external foreign matter and / or moisture from penetrating through holes formed at the outside of the pack cover 200 , concerns about performance degradation during use of the battery pack can be alleviated.

[0058] Meanwhile, a vehicle according to an embodiment of the present disclosure includes the above-described battery pack according to an embodiment of the present disclosure.

[0059] The present disclosure has been described in detail. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the present disclosure, are given by way of illustration only, as various changes and modifications within the scope of the present disclosure will become apparent to those skilled in the art from this detailed description.

Claims

1. A battery pack comprising: a module stack in which a plurality of battery modules are stacked; a battery pack cover having a lower cover configured to support the module stack at a lower side of the module stack and an upper cover coupled to the lower cover from an upper side of the module stack; a plurality of weld nuts secured to a lower surface of the lower housing; and a plurality of fastening bolts passing through the battery pack cover and the module stack and fastened to the weld nuts, Wherein, the lower outer cover comprises: a lower housing body configured to provide an accommodation space for the module stack; and an airtight plate assembly attached to a lower surface of the lower housing body and configured to provide an accommodation space for the weld nut, Wherein, the airtight plate assembly includes: a washer configured to cover the weld nut; and an airtight plate configured to press the gasket and attached to the lower surface of the lower housing, the gasket being interposed between the weld nut and the airtight plate, wherein an attachment groove is formed at the lower surface of the lower housing body, so that the airtight plate assembly is attached to the attachment groove, The airtight plate assembly is inserted into the attachment groove and fixed to the inner bottom surface of the attachment groove, and The depth of the attachment groove is equal to or greater than the height of the step of the airtight plate.

2. The battery pack according to claim 1, wherein: The airtight plate has a double-step structure, which is provided with a space for accommodating the gasket and a space for accommodating the welding nut.

3. The battery pack according to claim 1, wherein: The head of the fastening bolt is covered with a sealing member.

4. The battery pack according to claim 1, wherein The battery module includes: a unit module stack formed by coupling a plurality of unit modules; and A battery management system assembly is coupled to one longitudinal side of the unit module stack.

5. The battery pack according to claim 4, wherein: The battery management system assembly has a plurality of first fastening holes, and the plurality of first fastening holes are formed along the height direction of the battery management system assembly, and The unit module has: a plurality of second fastening holes formed at one longitudinal side of the unit module; and A plurality of third fastening holes are formed at the other longitudinal side of the unit module.

6. The battery pack according to claim 5, wherein: Among the plurality of fastening bolts, a first fastening bolt simultaneously passes through the first fastening hole and the second fastening hole overlapping each other, and a second fastening bolt simultaneously passes through the second fastening hole and the third fastening hole overlapping each other, so that the battery pack cover, the battery management system assembly, and the unit module stack are coupled at one time.

7. The battery pack according to claim 6, wherein: The unit module has a structure in which a plurality of battery cell groups are arranged along a width direction of the unit module, each of the battery cell groups having a plurality of battery cells arranged in a longitudinal direction of the unit module, and The third fastening holes are formed in dead spaces generated when adjacent battery cell groups are positioned to be shifted from each other.

8. A vehicle comprising the battery pack according to any one of claims 1 to 7.

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