CN220439500U - BDU structure with low temperature rise - Google Patents

Abstract

The utility model provides a low temperature rise BDU structure, which comprises a battery pack lower shell with a through channel, wherein a first end face and a second end face are arranged at intervals on two sides of the channel; at least one box body is fixedly arranged on the first end face and extends towards the second end face; the relay unit is fixedly arranged in at least one box body, and contacts of the relay unit extend towards the second end face along the axial direction of the channel; the contact of the relay unit is fixedly connected with the connecting copper bar; the heat conduction unit is propped against one end of the contact, close to the relay unit, of the copper bar, and the other end of the heat conduction unit extends out of at least one box body and extends towards the second end face; the circulating liquid cooling unit is arranged on the second end face of the battery pack lower shell, is propped against the end face, far away from the connecting copper bar, of the heat conducting unit, and is used for exchanging heat at the contact point of the connecting copper bar and the relay unit through the heat conducting unit. The scheme can effectively reduce the temperature rise of the relay under large current and reduce the attraction noise of the relay.

Description

BDU structure with low temperature rise

Technical Field

The utility model relates to the technical field of battery pack circuit breakers of new energy automobiles, in particular to a low-temperature-rise BDU structure.

Background

The battery pack breaker of the new energy automobile, namely Battery Distribution Unit, BDU for short. The BDU is integrated with a main relay, a pre-charging relay, an insurance tube, a detection element and the like. Along with the increase of the quick charging current and the increase of the voltage level of the whole vehicle, if the quick charging current of the existing new energy vehicle reaches 400A-600A, the system voltage reaches an 800V high-voltage platform, so that the heating value of the internal space of the small BDU is larger, the temperature rise of the conductive parts such as a relay, a copper bar and the like is quick, and the long-time stable operation of the BDU is adversely affected.

The Chinese patent publication No. CN115734589A discloses a BDU heat dissipation structure, which is characterized in that heat dissipation fins are additionally arranged, and the connection point between a copper bar and the outside is far away from the contact of a relay, but the structure inevitably increases the volume of the BDU, which is not beneficial to miniaturization of a battery module and improvement of energy density. Therefore, it is necessary to purposefully provide a BDU for a low temperature rise structure of an internal compact structure.

Disclosure of Invention

In view of this, the present utility model provides a low temperature rise BDU structure without changing the internal structural layout of the BDU.

The technical scheme of the utility model is realized as follows: the utility model provides a low temperature rise BDU structure, which comprises the following components:

the battery pack lower shell is provided with a through channel, and a first end face and a second end face are arranged at intervals on two sides of the channel in the axial extending direction;

the box body is fixedly arranged on the first end face, is also embedded into the channel and extends towards the second end face;

the relay unit is fixedly arranged in the at least one box body, and contacts of the relay unit extend towards the second end face along the axial direction of the channel; the contact of the relay unit is fixedly connected with one end of the connecting copper bar, and the other end of the connecting copper bar extends towards the direction away from the contact of the relay unit and is fixedly connected with at least one box body;

the heat conduction unit is propped against one end of the contact, close to the relay unit, of the copper bar, and the other end of the heat conduction unit extends out of at least one box body and extends towards the second end face;

the circulating liquid cooling unit is arranged on the second end face of the battery pack lower shell, is propped against the end face, far away from the connecting copper bar, of the heat conducting unit, and is used for exchanging heat at the contact point of the connecting copper bar and the relay unit through the heat conducting unit.

On the basis of the technical scheme, preferably, the heat conduction unit comprises a first body and a hollow protruding part, a first through hole penetrating through the first body is formed in the first body, the protruding part is arranged on the first body and surrounds the first through hole, one end of the protruding part is fixedly connected with the first body, the other end of the protruding part extends along the axial direction of the channel and penetrates through at least one box body to be abutted against the surface connected with the copper bar, and a contact of the relay unit is fixedly connected with the protruding part; the convex part is provided with a second through hole for the contact of the relay unit to pass through, and the side surface of the convex part in the axial extending direction is provided with a first notch; the inside of the protruding part is communicated with the first through hole, the second through hole and the first notch respectively.

Preferably, the heat conducting unit further comprises a flexible heat conducting pad; the first body is arranged with the surface of the circulating liquid cooling unit in a clearance way; the flexible heat conduction pad is arranged between the adjacent surfaces of the first body and the circulating liquid cooling unit and is fixedly connected with the first body and the circulating liquid cooling unit respectively.

Further preferably, an insulating film layer is further arranged on the surface of the circulating liquid cooling unit; the insulating film layer is provided with a plurality of third through holes, the size of each third through hole is matched with the outline of the flexible heat conduction pad, and the flexible heat conduction pad penetrates through the third through holes to be fixedly connected with the surface of the liquid cooling unit.

Further preferably, the cross-sectional dimension of the flexible thermal pad is greater than the cross-sectional dimension of the first body.

Further preferably, the circulating liquid cooling unit comprises a liquid cooling plate, a water inlet pipe and a water outlet pipe; the water inlet pipe and the water outlet pipe are in sealing connection with the liquid cooling plate along the axial direction of the channel, and the liquid cooling plate is propped against the surface of at least one box body extending into the channel; the liquid cooling plate is provided with a plurality of liquid cooling flow channels, and the liquid cooling flow channels are parallel and are arranged at intervals along the radial direction of the channel.

On the basis of the technical scheme, preferably, the at least one box body comprises an upper box body and a lower box body; the upper box body is clamped and fixed with the lower box body; the side surface of lower box is provided with a plurality of hollow annular joint portions, and a plurality of annular joint portions all correspond and are provided with the buffering connecting piece, and the buffering connecting piece is with lower box and battery package lower casing fixed connection.

Preferably, a second notch is arranged at one side of the annular clamping part far away from the lower box body; the buffer connecting piece comprises a hollow first annular section, a second annular section, a third annular section and a steel sleeve, wherein the first annular section, the second annular section and the third annular section are coaxially arranged and are communicated with each other, and the steel sleeve sequentially penetrates through the first annular section, the second annular section and the third annular section and is fixedly connected with the lower shell of the battery pack; the outer diameter of the steel sleeve does not exceed the size of the second notch; the first annular section, the second annular section and the third annular section are respectively in interference fit with the surface of the steel sleeve, the surface of the annular clamping part and the surface of the battery pack lower shell.

Preferably, the steel sleeve comprises a columnar second body and an end cover, and the second body is arranged in the first annular section, the second annular section and the third annular section in a penetrating manner; the end cover is fixedly connected with the second body and abuts against the end face, far away from the second annular section, of the first annular section, and the diameter of the end cover is larger than that of a virtual circle of the hollow part of the annular clamping part.

On the basis of the above technical scheme, preferably, the battery pack lower shell comprises at least one pair of cross beams and a pair of longitudinal beams, wherein the cross beams are parallel along the horizontal direction and are arranged at intervals, and each longitudinal beam is fixedly connected with the end part of the cross beam in the same extension direction; at least one pair of cross members and one pair of side members surround to form a channel.

Compared with the prior art, the low-temperature-rise BDU structure provided by the utility model has the following beneficial effects:

(1) According to the scheme, the heat conduction unit and the circulating liquid cooling unit with the heat conduction structure are arranged, so that the temperature rise degree of the relay unit under high current can be effectively reduced, and the problem of overlarge heating value in a compact space is solved;

(2) The further flexible heat conduction pad cooperation buffering connecting piece that sets up can reduce relay unit actuation's noise well, improves user's use experience.

Drawings

In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the utility model, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a perspective view of a low temperature rise BDU structure of the utility model;

FIG. 2 is an exploded perspective view of a low temperature rise BDU structure of the present utility model;

FIG. 3 is a front view of a low temperature rise BDU structure of the utility model;

FIG. 4 is a right side view of section A-A of FIG. 3;

FIG. 5 is a right side view of section B-B of FIG. 3;

FIG. 6 is a bottom view of a circulating liquid cooling unit of a low temperature rise BDU structure of the utility model;

fig. 7 is a perspective view of a low temperature rise BDU structure of the present utility model with the lower shell and part of the case of the battery pack removed;

FIG. 8 is a top view of a low temperature rise BDU structure of the utility model with the lower shell and portions of the shell removed;

FIG. 9 is a schematic view of the C-C cross-section rotation of FIG. 8;

FIG. 10 is a perspective view showing a combination of a first body and a boss of a low temperature rise BDU structure of the utility model;

FIG. 11 is a front view, in half section, of a buffer connector of a low temperature rise BDU structure of the utility model;

FIG. 12 is a front view, in semi-section, of a first annular segment, a second annular segment, and a third annular segment of a cryogenic BDU construction of the utility model;

fig. 13 is a front view of a steel jacket of a low temperature rise BDU structure according to the present utility model in semi-section.

Reference numerals: 1. a battery pack lower case; 100. a channel, 101, a first end face; 102. a second end face; 3. a relay unit; 200. connecting copper bars; 4. a heat conduction unit; 5. a circulating liquid cooling unit; 41. a first body; 42. a boss; 43. a first through hole; 44. a second through hole; 45. a first notch; 46. a flexible thermal pad; 300. an insulating film layer; 50. a third through hole; 51. a liquid cooling plate; 52. a water inlet pipe; 53. a water outlet pipe; 21. an upper case; 22. a lower box body; 23. an annular clamping part; 24. a buffer connection; 25. a second notch; 241. a first annular segment; 242. a second annular segment; 243. a third annular segment, 244, steel sleeve; 2441. a second body; 2442. an end cap.

Detailed Description

The following description of the embodiments of the present utility model will clearly and fully describe the technical aspects of the embodiments of the present utility model, and it is apparent that the described embodiments are only some embodiments of the present utility model, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present utility model without making any inventive effort, are intended to fall within the scope of the present utility model.

As shown in fig. 1, the present utility model provides a low temperature rise BDU structure, including:

the battery pack lower shell 1 is provided with a through channel 100, and a first end face 101 and a second end face 102 are arranged at intervals on two sides of the channel 100 in the axial extending direction; the space in the lower casing 1 of the battery pack and the channel 100 thereof is used for accommodating and placing at least one box body 2, so that the contact area with the at least one box body 2 can be increased, and the placement of the box body 2 is smoother.

In one embodiment of the scheme, the battery pack lower shell 1 comprises at least one pair of cross beams and a pair of longitudinal beams, wherein the cross beams are parallel along the horizontal direction and are arranged at intervals, and each longitudinal beam is fixedly connected with the end part of the cross beam in the same extending direction; at least one pair of cross members and one pair of side members circumscribe a channel 100. As can be seen from fig. 2, at least one pair of cross members and one pair of side members are each hollow square steel tube structures.

At least one casing 2 is fixedly arranged on the first end face 101, is also embedded in the channel 100 and extends towards the second end face 102.

The relay unit 3 is fixedly disposed within the at least one case 2, and contacts of the relay unit 3 extend toward the second end face 12 along the axial direction of the passage 100; the contact of the relay unit 3 is fixedly connected with one end of the connecting copper bar, and the other end of the connecting copper bar 200 extends towards the direction away from the contact of the relay unit 3 and is fixedly connected with at least one box body 2; the relay unit 3 is used as a trigger device and an overcurrent device, and generates a larger amount of heat under a high-current working condition. And the connection copper bar 200 is a member for connecting the contacts of the relay unit 3 and external input and output terminals. Heat can gather at the adjacent parts of the contact and the connecting copper bar 200, if heat exchange can not be carried out timely and effectively, the contact can not be reset reliably after the relay unit acts, and the hidden trouble that a loop can not be cut off effectively can be caused.

The heat conduction unit 4 is propped against one end of the contact, which is close to the relay unit 3, of the connecting copper bar 200, and the other end of the heat conduction unit extends out of at least one box body 2 and extends towards the second end face 102; the heat conducting unit 4 is attached to the contact and the end portion of the connection copper bar 200, and effectively transfers heat generated there.

The circulating liquid cooling unit 5 is arranged on the second end face 102 of the battery pack lower shell 1, and is propped against the end face, far away from the connecting copper bar 200, of the heat conducting unit 4, and is used for exchanging heat at the contact point of the connecting copper bar 200 and the relay unit 3 through the heat conducting unit 4. The circulating liquid cooling unit 5 can use a circulating pipeline of the battery module, and can also be independently provided with the circulating pipeline for heat exchange.

As shown in fig. 1, 2, 4, 9 and 10, the heat conducting unit 4 includes a first body 41 and a hollow protruding portion 42, a first through hole 43 penetrating through the first body 41 is provided on the first body 41, the protruding portion 42 is provided on the first body 41 and surrounds the first through hole 43, one end of the protruding portion 42 is fixedly connected with the first body 41, the other end of the protruding portion 42 extends along the axial direction of the channel 100 and passes through at least one box 2 to be abutted against the surface of the connection copper bar 200, and the contact point of the relay unit 3 is fixedly connected with the protruding portion 42; the bulge 42 is provided with a second through hole 44 for the contact of the relay unit 3 to pass through, and a first notch 45 is formed on the side surface of the bulge 42 in the axial extending direction; the inside of the boss 42 communicates with the first through hole 43, the second through hole 44, and the first notch 45, respectively. The box body 2 is correspondingly provided with a yielding hole for avoiding the convex part 42. The first body 41 is connected to the boss 42 and the circulating liquid cooling unit 5 to form a heat conduction path. The hollow structure of the first through hole of the first body 41 and the boss 42 facilitates the fastener to sequentially pass through the boss 42 and the connection copper bar 200 and to be fastened with the contact of the relay unit 3.

In order to adapt to the gap between the first body 41 and the circulating liquid cooling unit 5 and improve the heat conduction effect, the heat conduction unit 4 of the present solution further comprises a flexible heat conduction pad 46; the first body 41 is arranged in a clearance with the surface of the circulating liquid cooling unit 5; the flexible heat conducting pad 46 is disposed between the adjacent surfaces of the first body 41 and the circulating liquid cooling unit 5, and is fixedly connected with the first body 41 and the circulating liquid cooling unit 5, respectively. The flexible heat conducting pad 46 can be made of a material with good heat conducting effect, such as a heat conducting silica gel material, and can be well adhered to the surfaces of the first body 41 and the circulating liquid cooling unit 5.

Further preferably, in order to play an electric insulation protection effect, an insulation film layer 300 is further arranged on the surface of the circulating liquid cooling unit 5; the insulating film 300 is provided with a plurality of third through holes 50, the size of each third through hole 50 is adapted to the outline of the flexible heat conducting pad 46, and the flexible heat conducting pad 46 penetrates through the third through holes 50 to be fixedly connected with the surface of the liquid cooling unit. The dimensions of the insulating film 300 are adapted to the contour of the at least one casing 2 extending into the channel 100.

In order to facilitate adequate contact with the surface of the first body, as a preferred embodiment, the cross-sectional dimension of the flexible thermal pad 46 is greater than the cross-sectional dimension of the first body 41.

As shown in fig. 6 in combination with fig. 7, the circulating liquid cooling unit 5 includes a liquid cooling plate 51, a water inlet pipe 52, and a water outlet pipe 53; the water inlet pipe 52 and the water outlet pipe 53 are connected with the liquid cooling plate 51 in a sealing way along the axial direction of the channel 100, and the liquid cooling plate 51 is propped against the surface of at least one box body 2 extending into the channel 100; the liquid cooling plate 51 is provided with a plurality of liquid cooling channels, and the plurality of liquid cooling channels are arranged in parallel and at intervals along the radial direction of the channel 100. After the cooling liquid is fed into each liquid cooling runner through the water inlet pipe 52 for diversion, the cooling liquid is converged and discharged at the water outlet pipe to complete the circulation process, and the heat generated at the contact point of the relay unit is continuously taken away.

As shown in fig. 7, at least one case 2 of the present embodiment includes an upper case 21 and a lower case 22; the upper box body 21 is clamped and fixed with the lower box body 22; the side surface of lower box 22 is provided with a plurality of hollow annular joint portions 23, and a plurality of annular joint portions 23 all are provided with buffer connection piece 24 that corresponds, and buffer connection piece 24 is with lower box 22 and battery package lower casing 1 fixed connection. The adjacent terminal surfaces of last box and lower box are the opening setting, and adjacent side surface is provided with buckle and the clamp plate that coincide each other, realizes the detachable connection of last box and lower box, is convenient for install and maintain. The lower case 22 is further fastened to the lower case 1 of the battery pack by a plurality of buffer connectors 24.

As shown in fig. 7, 11, 12 and 13, specifically, a second notch 25 is provided on a side of the annular clamping portion 23 away from the lower case 22; the buffer connector 24 comprises a hollow first annular section 241, a second annular section 242, a third annular section 243 and a steel sleeve 244, wherein the first annular section 241, the second annular section 242 and the third annular section 243 are coaxially arranged and communicated with each other, and the steel sleeve 244 sequentially penetrates through the first annular section 241, the second annular section 242 and the third annular section 243 and is fixedly connected with the battery pack lower shell 1; the outer diameter of the steel sleeve 244 does not exceed the size of the second gap 25; the first annular section 241, the second annular section 242 and the third annular section 243 are respectively in interference fit with the surface of the steel sleeve 244, the surface of the annular clamping portion 23 and the surface of the lower battery pack housing 1. The second annular segment 242 has a significantly constricted shape that better accommodates the shape of the second gap 25 and the inner surface of the annular clamping portion 23, and the second annular segment 242 has an outer diameter that is slightly larger than the inner diameter of the second gap 25 and the annular clamping portion 23, thereby forming a tight fit. The diameter of the co-formed inner bore of the first, second and third annular sections 241, 242, 243 is also slightly larger than the outer diameter of the portion of the steel sleeve 244 that is threaded, again to form a tight fit between the surfaces. The first, second and third annular sections 241, 242 and 243 may be made of wear resistant rubber.

While the steel sleeve 244 comprises a cylindrical second body 2441 and an end cap 2442, the second body 2441 is threaded inside the first annular section 241, the second annular section 242 and the third annular section 243; the end cover 2442 is fixedly connected with the second body 2441 and abuts against the end surface of the first annular section 241, which is far away from the second annular section 242, and the diameter of the end cover 2442 is larger than that of the virtual circle of the hollow part of the annular clamping part 23. To fit the inner surface profile of the annular clamping portion 23, the cross-sectional area of the end cap 2442 is larger than the area of the virtual circle of the hollow portion of the annular clamping portion 23.

The relay unit of the scheme can also comprise main heating elements such as a fuse and a shunt, the relay heating is mainly concentrated at the contact, the heat generated at the relay contact can be effectively guided to the water cooling plate by the method, and the temperature rise of the relay contact is effectively reduced by cooling circulation, so that the relay is selected in a derating way.

In addition, the flexible heat conducting pad 46 and the buffer connector 24 of the scheme all use flexible materials, and especially the flexible heat conducting pad 46 can transfer heat, can also reduce mechanical noise generated by contact action of the relay unit, absorb assembly dimension chain tolerance, prevent local heat accumulation of the BDU, and are very suitable for BDU schemes with high-current charge and discharge requirements.

The foregoing description of the preferred embodiments of the utility model is not intended to be limiting, but rather is intended to cover all modifications, equivalents, alternatives, and improvements that fall within the spirit and scope of the utility model.

Claims (10)

1. A low temperature rise BDU structure comprising:

the battery pack lower shell (1) is provided with a through channel (100), and a first end face (101) and a second end face (102) are arranged at intervals on two sides of the channel (100) in the axial extending direction;

at least one box body (2) fixedly arranged on the first end face (101), and further embedded in the channel (100) and extending towards the second end face (102);

a relay unit (3) fixedly arranged in the at least one case (2), and contacts of the relay unit (3) extend toward the second end face (102) along an axial direction of the passage (100); the contact of the relay unit (3) is fixedly connected with one end of the connecting copper bar, and the other end of the connecting copper bar (200) extends towards the direction away from the contact of the relay unit (3) and is fixedly connected with at least one box body (2);

the heat conduction unit (4) is propped against one end of the contact close to the relay unit (3) of the connecting copper bar (200), and the other end of the heat conduction unit extends out of at least one box body (2) and extends towards the second end face (102);

the circulating liquid cooling unit (5) is arranged on the second end face (102) of the battery pack lower shell (1) and is propped against the end face, far away from the connecting copper bar (200), of the heat conducting unit (4) and is used for exchanging heat at the contact point of the connecting copper bar (200) and the relay unit (3) through the heat conducting unit (4).

2. A low temperature rising BDU structure according to claim 1, characterized in that the heat conducting unit (4) comprises a first body (41) and a hollow protruding part (42), the first body (41) is provided with a first through hole (43) penetrating through, the protruding part (42) is arranged on the first body (41) and surrounds the first through hole (43), one end of the protruding part (42) is fixedly connected with the first body (41), the other end of the protruding part (42) extends along the axial direction of the channel (100) and passes through at least one box body (2) to be abutted on the surface of the connecting copper bar (200), and the contact of the relay unit (3) is fixedly connected with the protruding part (42); the bulge (42) is provided with a second through hole (44) for the contact of the relay unit (3) to pass through, and a first notch (45) is formed on the side surface of the bulge (42) in the axial extending direction; the inside of the bulge (42) is respectively communicated with the first through hole (43), the second through hole (44) and the first notch (45).

3. A low temperature rising BDU structure according to claim 2 characterized in that the heat conducting unit (4) further comprises a flexible heat conducting pad (46); the first body (41) is arranged in a clearance with the surface of the circulating liquid cooling unit (5); the flexible heat conduction pad (46) is arranged between the adjacent surfaces of the first body (41) and the circulating liquid cooling unit (5) and is fixedly connected with the first body (41) and the circulating liquid cooling unit (5) respectively.

4. A low temperature rising BDU structure according to claim 3, characterized in that the surface of the circulating liquid cooling unit (5) is further provided with an insulating film layer (300); a plurality of third through holes (50) are formed in the insulating film layer (300), the size of each third through hole (50) is matched with the outline of the flexible heat conduction pad (46), and the flexible heat conduction pad (46) penetrates through the third through holes (50) to be fixedly connected with the surface of the liquid cooling unit.

5. A low temperature rising BDU structure according to claim 3 characterized in that the cross-sectional dimension of the flexible thermal pad (46) is larger than the cross-sectional dimension of the first body (41).

6. A low temperature rising BDU structure according to claim 3, characterized in that the circulating liquid cooling unit (5) comprises a liquid cooling plate (51), a water inlet pipe (52) and a water outlet pipe (53); the water inlet pipe (52) and the water outlet pipe (53) are connected with the liquid cooling plate (51) in a sealing way along the axial direction of the channel (100), and the liquid cooling plate (51) is propped against the surface of at least one box body (2) extending into the channel (100); the liquid cooling plate (51) is provided with a plurality of liquid cooling flow channels which are parallel and spaced along the radial direction of the channel (100).

7. A low temperature rising BDU structure according to claim 1 characterized in that the at least one tank (2) comprises an upper tank (21) and a lower tank (22); the upper box body (21) is clamped and fixed with the lower box body (22); the side surface of lower box (22) is provided with a plurality of hollow annular joint portion (23), and a plurality of annular joint portion (23) all correspond and are provided with buffering connecting piece (24), and buffering connecting piece (24) are with lower box (22) and battery package lower casing (1) fixed connection.

8. A low temperature rising BDU structure according to claim 7, characterized in that, a second notch (25) is arranged at one side of the annular clamping part (23) far away from the lower box body (22); the buffer connecting piece (24) comprises a hollow first annular section (241), a second annular section (242), a third annular section (243) and a steel sleeve (244), wherein the first annular section (241), the second annular section (242) and the third annular section (243) are coaxially arranged and communicated with each other, and the steel sleeve (244) sequentially penetrates through the first annular section (241), the second annular section (242) and the third annular section (243) and is fixedly connected with the lower battery pack shell (1); the outer diameter of the steel sleeve (244) does not exceed the size of the second notch (25); the first annular section (241), the second annular section (242) and the third annular section (243) are respectively in interference fit with the surface of the steel sleeve (244), the surface of the annular clamping part (23) and the surface of the lower battery pack shell (1).

9. A low temperature raising BDU structure according to claim 8, characterized in that the steel sleeve (244) comprises a cylindrical second body (2441) and an end cap (2442), the second body (2441) being threaded inside the first annular section (241), the second annular section (242) and the third annular section (243); the end cover (2442) is fixedly connected with the second body (2441) and abuts against the end face, far away from the second annular section (242), of the first annular section (241), and the diameter of the end cover (2442) is larger than that of a virtual circle of the hollow part of the annular clamping part (23).

10. A low temperature raising BDU structure according to claim 1, characterized in that said battery pack lower case (1) includes at least one pair of cross members and a pair of side members, said at least one pair of cross members being arranged in parallel and at intervals along the horizontal direction, each side member being fixedly connected with the end portions of the at least one pair of cross members in the same extending direction, respectively; at least one pair of cross members and one pair of side members surround to form a channel (100).