CN216354505U - Lower shell of battery pack and battery device - Google Patents

Abstract

The utility model provides a lower shell of a battery pack and a battery device, and relates to the technical field of batteries. This casing battery package casing under battery package includes bottom plate, crossbeam, longeron and a plurality of first curb plate and a plurality of second curb plate. A plurality of first curb plates and a plurality of second curb plate all fixed connection in bottom plate edge. The longitudinal beam is welded on the bottom plate, and the at least two first side plates are respectively positioned at two ends of the longitudinal beam; a distance is reserved between one end of the longitudinal beam and the first side plate. The cross beam and the longitudinal beam are arranged in a crossed manner, the cross beam is connected with the longitudinal beam in a welding manner, and the cross beam is connected with the bottom plate in a welding manner; the two ends of the cross beam are respectively connected to the two second side plates. The battery device provided by the utility model adopts the battery pack lower shell. The lower shell of the battery pack and the battery device provided by the utility model can solve the technical problems that the lower shell of the battery pack is easy to deform, low in strength and difficult to lighten in the prior art.

Description

A lower case of a battery pack and a battery device

technical field

The utility model relates to the technical field of batteries, in particular to a lower case of a battery pack and a battery device.

Background technique

The contemporary automobile industry is undergoing revolutionary changes, that is, traditional fuel vehicles are gradually being replaced by new energy vehicles. Among them, pure electric vehicles are emerging as a kind of new energy vehicles. Many transmission fuel vehicle platforms directly replace the engine structure with power. The battery pack structure replaces the power source of the car from fuel to battery. The lightweight of the battery pack is related to the energy density of the battery pack, which in turn is related to the subsidies for new energy. In order to improve the competitiveness of the product, the mainstream material of the lower casing of the battery pack is used. After three generations of material replacement of sheet metal, cast aluminum, and aluminum alloy extruded profiles, the mainstream material of the lower shell of the battery pack at this stage is profile welding. Simple, mostly composed of bottom plate, transverse beam and frame welding.

In the prior art, the lower shell is made of a single-layer aluminum plate, and the interior is mostly welded with solder blocks, and then holes are opened to install and fix components such as modules and cold plates. Deformation, and the strength of the welding area is reduced. The large number of welding blocks will also complicate the welding process. The welding blocks need to be solid welding blocks, which cannot play a lightweight role. The position of the block weld bead also needs to avoid the welding position of the internal beam, and the bottom plate is divided into 3-4 small bottom plates in the horizontal direction for welding.

Utility model content

The purpose of the present invention includes providing a lower case of a battery pack, which can improve the technical problems in the prior art that the lower case of the battery pack is easily deformed, has low strength and is difficult to lighten.

The purpose of the present invention also includes providing a battery device, which can improve the technical problems in the prior art that the lower case of the battery pack is easily deformed, the strength is low, and the weight is difficult.

Embodiments of the present utility model can be implemented as follows:

An embodiment of the present utility model provides a battery pack lower casing, the battery pack lower casing includes a bottom plate, a cross beam, a longitudinal beam, a plurality of first side plates and a plurality of second side plates;

a plurality of the first side plates and a plurality of the second side plates are fixedly connected to the edge of the bottom plate;

The longitudinal beam is welded to the bottom plate, and at least two of the first side plates are respectively located at two ends of the longitudinal beam; one end of the longitudinal beam is spaced from the first side plate;

The cross beams and the longitudinal beams are arranged crosswise, and the transverse beams and the longitudinal beams are welded and connected, and the transverse beams are welded and connected to the bottom plate; both ends of the transverse beams are respectively connected to the two second side plates.

The beneficial effects of the lower case of the battery pack provided by the present invention relative to the prior art include:

In the lower case of the battery pack, a longitudinal beam is welded on a bottom plate to improve the overall strength of the bottom plate through the longitudinal beam, and the welding step of splicing a plurality of flat plates to form a bottom plate can be omitted, thereby achieving the purpose of preventing the deformation of the bottom plate. , By welding the longitudinal beams on the bottom plate to improve the overall strength of the bottom plate through the longitudinal beams. In other words, the lower case of the battery pack not only reduces the welding process, improves the welding strength, and avoids the welding deformation of the bottom plate; at the same time, it can also reduce the use of welding blocks, so that the purpose of light weight can be easily achieved. Therefore, the lower case of the battery pack can improve the technical problems of the lower case of the battery pack that are easily deformed, low in strength and difficult to lighten in the prior art.

Optionally, the lower case of the battery pack further includes a reinforcing member; the reinforcing member is welded to the bottom plate, and one end of the reinforcing member is connected to the longitudinal beam, and the other end is connected to the first side plate .

Optionally, the reinforcing member includes a first reinforcing portion and a second reinforcing portion; the first reinforcing portion and the second reinforcing portion are connected to each other and are arranged at an included angle; the first reinforcing portion and the first reinforcing portion are Two reinforcing parts are welded to the bottom plate; one end of the first reinforcing part is connected to the longitudinal beam; one end of the second reinforcing part is connected to the other end of the first reinforcing part; the second reinforcing part The part is attached to the first side plate and welded to the first side plate.

Optionally, the longitudinal beam includes a beam main body and a plurality of mounting parts; a plurality of the mounting parts are arranged at intervals along the extending direction of the beam main body, and the mounting parts are used for assembling the fixing module or the battery device. Water cooling plate.

Optionally, the beam main body is provided with a plurality of grooves, and the plurality of grooves are all formed along the extending direction of the beam main body.

Optionally, a convex block is provided on the side of the beam facing the first side plate, and the convex block is disposed on the side of the beam close to the side of the bottom plate; and the convex block and the Bottom plate welding.

Optionally, an accommodating groove is formed in the middle of the cross beam, and the accommodating groove is located above the longitudinal beam; the accommodating groove is used for installing a cooling water channel pipe.

Optionally, a wire harness fixing portion is further provided on the beam, and the wire harness fixing portion is used to fix the conductive wire; the wire harness fixing portion is protruded on the side of the beam away from the bottom plate, and is located in the accommodating groove on both sides.

Optionally, there are a plurality of the beams, the plurality of beams are arranged at intervals, and the plurality of beams are parallel to each other.

A battery device includes a lower case of a battery pack. the lower case of the battery pack, the lower case of the battery pack includes a bottom plate, a cross beam, a longitudinal beam, a plurality of first side plates and a plurality of second side plates;

a plurality of the first side plates and a plurality of the second side plates are fixedly connected to the edge of the bottom plate;

The longitudinal beam is welded to the bottom plate, and at least two of the first side plates are respectively located at two ends of the longitudinal beam; one end of the longitudinal beam is spaced from the first side plate;

The cross beams and the longitudinal beams are arranged crosswise, and the transverse beams and the longitudinal beams are welded and connected, and the transverse beams are welded and connected to the bottom plate; both ends of the transverse beams are respectively connected to the two second side plates.

The battery device provided by the present invention adopts the above-mentioned lower case of the battery pack, and the beneficial effects of the battery device relative to the prior art are the same as those of the lower case of the battery pack provided above relative to the prior art. This will not be repeated here.

Description of drawings

In order to illustrate the technical solutions of the embodiments of the present invention more clearly, the accompanying drawings that need to be used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention. Therefore, it should not be regarded as a limitation of the scope. For those of ordinary skill in the art, other related drawings can also be obtained from these drawings without any creative effort.

FIG. 1 is a schematic structural diagram of a lower case of a battery pack provided in an embodiment of the application;

FIG. 2 is a schematic partial structure diagram of the lower case of the battery pack provided in the embodiment of the application;

FIG. 3 is another partial structural schematic diagram of the lower case of the battery pack provided in the embodiment of the present application.

Icon: 10-battery pack lower case; 100-bottom plate; 200-stringer; 110-reinforcing piece; 111-first reinforcement part; 112-second reinforcement part; 120-beam main body; 121-groove; 130- 300-beam; 310-bump; 320-accommodating groove; 330-wire harness fixing part; 410-first side plate; 420-second side plate.

Detailed ways

In order to make the purposes, technical solutions and advantages of the embodiments of the present utility model clearer, the technical solutions in the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present utility model. The embodiments described above are a part of the embodiments of the present invention, but not all of the embodiments. The components of the embodiments of the invention generally described and illustrated in the drawings herein may be arranged and designed in a variety of different configurations.

Accordingly, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but is merely representative of selected embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present invention.

It should be noted that like numerals and letters refer to like items in the following figures, so once an item is defined in one figure, it does not require further definition and explanation in subsequent figures.

In the description of the present utility model, it should be noted that, if the azimuth or positional relationship indicated by the terms "upper", "down", "inner", "outer", etc. appears, it is based on the azimuth or positional relationship shown in the accompanying drawings, Or the orientation or positional relationship that the utility model product is usually placed in use is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation or a specific orientation. construction and operation, and therefore should not be construed as a limitation of the present invention.

In addition, where the terms "first", "second" and the like appear, they are only used to differentiate the description, and should not be construed as indicating or implying relative importance.

It should be noted that the features in the embodiments of the present invention may be combined with each other under the condition of no conflict.

The present application provides a battery device (not shown in the figure), which can be applied to electrical equipment to provide electrical energy to the electrical equipment, so that the electrical equipment can run stably. Among them, the electrical equipment can be electric vehicles, industrial electrical equipment, and other electrical machinery and equipment.

The battery device includes a lower casing 10 of a battery pack and a plurality of battery modules (not shown), the plurality of battery modules are assembled on the lower casing 10 of the battery pack, and the plurality of battery modules are used to output electrical energy to the outside , to provide electrical energy to the electrical equipment. The lower casing 10 of the battery pack is used to provide a bearing function for a plurality of battery modules.

In the prior art, the lower case of the battery pack is mostly formed by welding and splicing a plurality of flat plate structures, so that the lower case of the battery pack is deformed after multiple welding processes, thereby reducing the strength of the lower case of the battery pack Moreover, since solid solder blocks are used for many times of welding, after the welding process is completed, the weight of the lower casing of the battery pack increases, which greatly hinders the lightweight of the lower casing of the battery pack.

In order to improve the above technical problems, in other words, in order to improve the technical problems that the lower case 10 of the battery pack is easily deformed, the strength is low and the weight is difficult to reduce in the prior art, the lower case 10 of the battery pack in the present application and the battery using the same are provided. The battery unit that encloses the case 10 .

1 , the lower case 10 of the battery pack includes a bottom plate 100 , a cross beam 300 , a longitudinal beam 200 , a plurality of first side plates 410 and a plurality of second side plates 420 . It should be noted that, in the embodiment of the present application, the cross beam 300 , the longitudinal beam 200 , the plurality of first side plates 410 and the plurality of second side plates 420 are all connected to the bottom plate 100 , in other words, the bottom plate 100 is a whole plate-like structure. Therefore, the method of splicing and welding through a plurality of flat plate structures in the prior art can be omitted, thereby preventing the deformation of the bottom plate 100 . The plurality of first side plates 410 and the plurality of second side plates 420 are fixedly connected to the edge of the bottom plate 100 . In order to improve the overall strength of the bottom plate 100 , the longitudinal beams 200 are welded to the bottom plate 100 . By welding the longitudinal beams 200 to the bottom plate 100 , the bending resistance of the bottom plate 100 along the direction in which the longitudinal beams 200 are arranged can be improved, thereby improving the overall strength of the bottom plate 100 . At least two first side plates 410 are located at both ends of the longitudinal beam 200, respectively. The cross beam 300 and the longitudinal beam 200 are crossed and connected, and the cross beam 300 and the longitudinal beam 200 are connected by welding, and the cross beam 300 is welded and connected with the bottom plate 100; the cross beam 300 is welded on the bottom plate 100 and crossed with the longitudinal beam 200, which can improve the bottom plate 100 along the cross beam. The bending resistance in the direction in which the 300 is arranged, thereby further improving the overall strength of the base plate 100 . Both ends of the beam 300 are respectively connected to the two second side plates 420 . In addition, since another part structure needs to be provided on the bottom plate 100 near one end of the longitudinal beam 200 , there is a distance between one end of the longitudinal beam 200 and the first side plate 410 .

As mentioned above, the lower case 10 of the battery pack can improve the overall strength of the bottom plate 100 through the longitudinal beams 200 by welding the longitudinal beams 200 on an integral bottom plate 100 , which can save the welding step of splicing a plurality of flat plates to form the bottom plate 100 . Therefore, the purpose of preventing the deformation of the bottom plate 100 is achieved, and at the same time, the longitudinal beams 200 are welded on the bottom plate 100 to improve the overall strength of the bottom plate 100 through the longitudinal beams 200 . In other words, the lower case 10 of the battery pack not only reduces the welding process, improves the welding strength, and avoids the welding deformation of the bottom plate 100; at the same time, it can also reduce the use of solder bumps, so that the purpose of light weight can be easily achieved. Therefore, the lower case 10 of the battery pack can improve the technical problems that the lower case 10 of the battery pack is easily deformed, has low strength and is difficult to reduce in weight in the prior art.

It is worth noting that, please refer to FIG. 1 and FIG. 2 in combination, wherein the arrangement of the longitudinal beam 200 , the transverse beam 300 , the plurality of first side plates 410 and the plurality of second side plates 420 can improve the bottom plate 100 Therefore, the bottom plate 100 can be set as a whole bottom plate 100, and the method of splicing a plurality of flat plate structures to form the bottom plate 100 is omitted. Based on this, the overall strength of the bottom plate 100 can be improved, and the technical problems in the prior art that the lower case 10 of the battery pack is easily deformed, low in strength, and difficult to reduce in weight can be improved.

In addition, in some embodiments of the present application, the longitudinal beams 200 are substantially plate-shaped, and the longitudinal beams 200 are substantially welded to the bottom plate 100 , so that the weight of the bottom plate 100 can be improved while the strength of the bottom plate 100 is improved. The middle part of the beam 300 is welded on the longitudinal beam 200, so that the beam 300 is connected with the longitudinal beam 200, so as to improve the overall structural strength.

Optionally, please refer to FIG. 1 and FIG. 3 in combination, in some embodiments of the present application, the longitudinal beam 200 includes a beam main body 120 and a plurality of installation parts 130 ; the plurality of installation parts 130 are spaced along the extension direction of the beam main body 120 Arranged and arranged, the mounting portion 130 is used for assembling a fixed module (not shown) or a water cooling plate (not shown) of the battery device. It should be noted that, multiple modules need to be assembled on the lower case 10 of the battery pack to form a battery device. When the longitudinal beams 200 are welded on the bottom plate 100 , a plurality of mounting parts 130 can be provided on the longitudinal beams 200 to assemble a plurality of fixed modules and water-cooling plates through the mounting parts 130 , so that the fixed modules and the water-cooled plates can be omitted. The welding process on the base plate 100 reduces the number of welding processes, which not only further improves the strength of the base plate 100 , but also prevents the welding deformation of the base plate 100 .

It should be noted that, the plurality of mounting parts 130 may be provided with structures such as threaded sleeves and nut holes to assemble the fixed module and the water cooling plate. Of course, a buckle structure or an adhesive structure can also be provided on the mounting portion 130 to realize the assembly of the fixed module and the water cooling plate.

In addition, in order to facilitate the lightening of the lower case 10 of the battery pack, in some embodiments of the present application, the beam main body 120 is provided with a plurality of grooves 121 , and the plurality of grooves 121 are all formed along the extending direction of the beam main body 120 . . Through the arrangement of the grooves 121, the overall mass of the beam main body 120 can be reduced, so that the lower case 10 of the battery pack can be easily reduced in weight. It should be noted that by setting the opening direction of the groove 121 along the extending direction of the beam body 120 , the side walls forming the groove 121 can be set along the extending direction of the beam body 120 , so that the side walls of the groove 121 can be formed to improve the The bending strength of the beam main body 120 , in other words, the grooves 121 arranged along the extending direction of the beam main body 120 are provided on the beam main body 120 , which can not only realize the lightweight of the lower battery case 10 , but also ensure the integrity of the longitudinal beam 200 . strength to improve the overall strength of the bottom plate 100 .

Wherein, a plurality of grooves 121 may be opened between every two adjacent and spaced mounting portions 130 , and the plurality of grooves 121 are arranged in parallel along the width direction of the beam body 120 , thereby forming a plurality of grooves 121 extending along the beam body 120 The strip-shaped protrusion in the direction of the strip-shaped protrusion forms the side wall of the groove 121 . The overall strength of the beam main body 120 can be improved by the arrangement of the plurality of bar-shaped protrusions.

In order to further improve the overall strength of the longitudinal beam 200, in the embodiment of the present application, the lower case 10 of the battery pack further includes a reinforcement 110; the reinforcement 110 is welded to the bottom plate 100, and one end of the reinforcement 110 is connected to the longitudinal beam 200, The other end is connected to the first side plate 410 . It should be noted that, since there is a certain distance between one end of the longitudinal beam 200 and one of the first side plates 410, one end welded by the reinforcing member 110 is connected to the longitudinal beam 200, and the other end is connected to the first side plate 410, so that it is possible to The stability of welding the longitudinal beam 200 on the bottom plate 100 is improved.

Wherein, in order to prevent the reinforcement member 110 from affecting the assembly of other parts structures close to the end of the longitudinal beam 200 , the reinforcement structure is arranged on both sides of the longitudinal beam 200 in the width direction, so as to avoid the space between the end of the longitudinal beam 200 and the first side plate 410 space to ensure the arrangement of other structural parts at the end of the longitudinal beam 200 .

Optionally, the reinforcement member 110 includes a first reinforcement part 111 and a second reinforcement part 112 . The first reinforcement portion 111 and the second reinforcement portion 112 are connected to each other and are arranged at an included angle; both the first reinforcement portion 111 and the second reinforcement portion 112 are welded to the bottom plate 100 . One end of the first reinforcement portion 111 is connected to the longitudinal beam 200 ; the end portion of the first reinforcement portion 111 is connected to one of the ends of the longitudinal beam 200 in the width direction. Also, the first reinforcement portion 111 extends obliquely toward the first side plate 410 . One end of the second reinforcement portion 112 is connected to the other end of the first reinforcement portion 111 ; the second reinforcement portion 112 is attached to the first side plate 410 and welded to the first side plate 410 . It should be noted that there are two first reinforcing parts 111 and two second reinforcing parts 112 , the two first reinforcing parts 111 are respectively disposed on both sides of the longitudinal beam 200 in the width direction, and the two second reinforcing parts 112 are They are respectively connected to the first reinforcing parts 111 , and the two second reinforcing parts 112 are also respectively located on both sides of the longitudinal beam 200 in the width direction, and the reinforcing member 110 has a figure-eight shape as a whole.

Due to the extension of the first reinforcement portion 111 toward the first side plate 410 , the reinforcement member 110 can indirectly connect the longitudinal beam 200 and the first side plate 410 ; through the arrangement of the second reinforcement portion 112 , the connection between the reinforcement member 110 and the first side plate 410 can be improved. The connection stability of the first side plate 410 .

It should be understood that in other embodiments of the application, the reinforcing member 110 may also be arranged in other manners, for example, the reinforcing member 110 is linear, one end of the reinforcing member 110 is connected to the longitudinal beam 200, and the other end is connected to the first side plate 410 is sufficient, and at this time, the reinforcing member 110 is inclined to the longitudinal beam 200 and the like.

In addition, in the embodiment of the present application, in order to improve the problem that the beam 300 is easily deformed due to excessive stress concentration after welding with the longitudinal beam 200 , the lateral beam 300 facing the first side plate 410 is provided with a bump 310 . The block 310 is disposed on the side of the beam 300 close to the side of the bottom plate 100 ; and the bump 310 is welded with the bottom plate 100 . It should be noted that the position of the bump 310 on the beam 300 can be determined according to the actual situation, and the bump 310 can be arranged on the end of the beam 300 close to the second side plate 420, such as the bump 310 denoted by A in FIG. 1 . ; Bump 310 can also be arranged in the middle of the beam 300 close to the position of the longitudinal beam 200, such as the bump 310 referred to by B in FIG. 1 .

It is worth noting that the location of the bump 310 can be set according to the stress concentration position of the beam 300 after welding. At this time, the bump 310 can be arranged at the end of the beam 300 close to the second side plate 420 to improve the problem that the beam 300 is easily deformed due to stress concentration. For another example, if the beam 300 is welded on the bottom plate 100 and the longitudinal beam 200, so that the stress concentration position of the beam 300 is located in the middle of the beam 300 and close to the longitudinal beam 200, at this time, the bump 310 can be arranged in the middle of the beam 300 and close to the longitudinal beam 200 position.

Of course, the bumps 310 can also be provided in multiples, so as to improve the problem that the beam 300 is easily deformed due to excessive stress concentration of the beam 300 through the plurality of bumps 310 . Of course, the plurality of bumps 310 may be arranged in contact with each other, or may be arranged at intervals.

Optionally, in some embodiments of the present application, an accommodating groove 320 is formed in the middle of the beam 300 , and the accommodating groove 320 is located above the longitudinal beam 200 ; the accommodating groove 320 is used for installing a cooling water channel pipe. In the case of assembling the cooling water channel pipe, the accommodating groove 320 on the beam 300 can provide a guiding function for the cooling water channel pipe, so as to facilitate the assembly of the cooling water channel pipe. At the same time, the accommodating groove 320 can also provide the cooling water channel pipe with positioning and limiting functions, thereby ensuring the installation accuracy and installation stability of the cooling water channel pipe.

In addition, the beam 300 is also provided with a wire harness fixing portion 330 for fixing the conductive wires; It should be noted that the wire harness fixing portion 330 can be provided with threaded holes for assembling the wire harness bracket to facilitate the assembly of the wire harness bracket, thereby providing a fixing effect on the conductive wire through the wire harness bracket and improving the installation stability of the conductive wire. In addition, a side of the end of the beam 300 facing the first side plate 410 is also provided with a threaded hole, the threaded hole is used for assembling the mica board, so as to facilitate the installation and setting of the mica board.

Of course, in the embodiment of the present application, there are multiple beams 300 , the multiple beams 300 are arranged at intervals, and the multiple beams 300 are parallel to each other. Disposing a plurality of beams 300 on the bottom plate 100 can not only provide sufficient reinforcement to the bottom plate 100, but at the same time, through the accommodating grooves 320 opened on the plurality of beams 300, it can ensure that the cooling water channel pipes provide effective guiding and positioning functions And the limit function, so as to ensure the assembly accuracy and assembly stability of the cooling water channel pipe. The plurality of wire harness fixing portions 330 on the plurality of beams 300 can also provide effective stabilization for the conductive wires, thereby improving the stability of the wire harness formed by the conductive wires.

To sum up, in the battery pack lower case 10 and the battery device provided in the embodiments of the present application, the longitudinal beams 200 can be welded on one bottom plate 100 to improve the overall strength of the bottom plate 100 through the longitudinal beams 200 , and multiple The welding step of forming the bottom plate 100 by splicing the flat plates achieves the purpose of preventing the bottom plate 100 from being deformed. In other words, the lower case 10 of the battery pack not only reduces the welding process, improves the welding strength, and avoids the welding deformation of the bottom plate 100; at the same time, it can also reduce the use of solder bumps, so that the purpose of light weight can be easily achieved. Therefore, the lower case 10 of the battery pack can improve the technical problems that the lower case 10 of the battery pack is easily deformed, has low strength and is difficult to reduce in weight in the prior art.

The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art who is familiar with the technical field of the present invention can easily think of changes within the technical scope disclosed by the present invention. Or replacement should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims (10)

1. The lower battery pack shell is characterized by comprising a bottom plate, a cross beam, a longitudinal beam, a plurality of first side plates and a plurality of second side plates;

the first side plates and the second side plates are fixedly connected to the edge of the bottom plate;

the longitudinal beam is welded on the bottom plate, and the at least two first side plates are respectively positioned at two ends of the longitudinal beam; a gap is reserved between one end of the longitudinal beam and the first side plate;

the cross beam and the longitudinal beam are arranged in a crossed mode, the cross beam is connected with the longitudinal beam in a welded mode, and the cross beam is connected with the bottom plate in a welded mode; and two ends of the cross beam are respectively connected to the two second side plates.

2. The battery pack lower case according to claim 1, wherein the battery pack lower case further comprises a reinforcement; the reinforcing piece is welded on the bottom plate, one end of the reinforcing piece is connected with the longitudinal beam, and the other end of the reinforcing piece is connected with the first side plate.

3. The battery pack lower case according to claim 2, wherein the reinforcement includes a first reinforcement portion and a second reinforcement portion; the first reinforcing part and the second reinforcing part are connected with each other and arranged in an included angle; the first reinforcing part and the second reinforcing part are welded to the bottom plate; one end of the first reinforcing part is connected to the longitudinal beam; one end of the second reinforcing part is connected to the other end of the first reinforcing part; the second reinforcing part is attached to the first side plate and welded to the first side plate.

4. The battery pack lower case according to claim 1, wherein the longitudinal beam includes a beam main body and a plurality of mounting portions; a plurality of the installation department is followed the extending direction interval ground of roof beam main part arranges the setting, the installation department is used for assembling battery device's fixed module or water-cooling board.

5. The battery pack lower casing of claim 4, wherein the beam body defines a plurality of grooves, and the plurality of grooves are disposed along an extension direction of the beam body.

6. The lower battery pack case according to any one of claims 1 to 5, wherein a projection is provided on a side of the cross member facing the first side plate, the projection being provided on a side of the cross member adjacent to the bottom plate; and the lug is welded with the bottom plate.

7. The battery pack lower case according to any one of claims 1 to 5, wherein a receiving groove is formed in the middle of the cross member, and the receiving groove is located above the longitudinal member; the containing groove is used for installing a cooling water channel pipe.

8. The battery pack lower case according to claim 7, wherein a harness fixing portion for fixing a conductive wire is further provided on the cross member; the wire harness fixing part is convexly arranged on one side of the beam far away from the bottom plate and is positioned on two sides of the accommodating groove.

9. The battery pack lower case according to any one of claims 1 to 5, wherein the cross member is plural, and the plural cross members are provided at intervals and are parallel to each other.

10. A battery device comprising the battery pack lower case according to any one of claims 1 to 9.

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