CN114639909B

CN114639909B - Shell of battery pack and manufacturing method thereof

Info

Publication number: CN114639909B
Application number: CN202210316387.6A
Authority: CN
Inventors: 孟令洋; 刘嘉琦; 徐林
Original assignee: Envision Power Technology Jiangsu Co Ltd; Envision Ruitai Power Technology Shanghai Co Ltd
Current assignee: Envision Power Technology Jiangsu Co Ltd; Envision Ruitai Power Technology Shanghai Co Ltd
Priority date: 2022-03-29
Filing date: 2022-03-29
Publication date: 2024-04-19
Anticipated expiration: 2042-03-29
Also published as: CN114639909A

Abstract

The invention discloses a shell of a battery pack and a manufacturing method thereof, wherein the shell of the battery pack comprises: the side frames are arranged along the first direction, and the side frames are arranged along the second direction; the axis of the side frame is arranged along the first direction, the side frame is arranged between the pair of end plates, and two ends of the side frame along the first direction are respectively connected with the pair of end plates in a welding way; and a welding notch is formed at the welding position between the end plate and the side frame, and the welding wire is operatively filled in the welding notch. Because the end plate of the shell is an as-cast aluminum alloy end plate, that is to say, the end plate is formed by casting aluminum alloy, the cost of the end plate is very low because the casting process is simple, and the cost of one end plate is about ten yuan, so that the cost can be effectively saved.

Description

Shell of battery pack and manufacturing method thereof

Technical Field

The embodiment of the invention relates to the field of batteries, in particular to a shell of a battery pack and a manufacturing method thereof.

Background

With the rapid development of electric vehicles, the energy density and the safety requirements of battery packs are higher and higher, and the battery packs have a trend of improving the energy density of the battery packs and reducing the cost.

In the current battery pack, an end plate is generally adopted to support an output electrode of the battery pack, an output seat is generally required to be arranged on the end plate, the structure of the end plate is generally complex for conveniently installing the output seat and the like, the current end plate is generally formed by machining, the machining cost is very high, and the machining cost of one end plate can reach more than two hundred.

Disclosure of Invention

An object of an embodiment of the present invention is to provide a case of a battery pack and a method of manufacturing the same, which enable the production costs of the battery pack to be reduced.

To solve the above technical problems, embodiments of the present invention provide a housing of a battery pack, including:

The pair of end plates are oppositely arranged along the first direction, and the end plates are as-cast aluminum alloy end plates; and

The axis of the side frame is arranged along the first direction, the side frame is arranged between the pair of end plates, and two ends of the side frame along the first direction are respectively connected with the pair of end plates in a welding way;

And a welding notch is formed at the welding position between the end plate and the side frame, and the welding wire is operatively filled in the welding notch.

Compared with the prior art, the end plate of the shell is an as-cast aluminum alloy end plate, namely the end plate is formed by casting of aluminum alloy, and the manufacturing cost of the end plate is very low due to the simple casting process, and the price of one end plate is about ten yuan, so that the cost can be effectively saved.

However, the inventor finds that the end plate cast and formed by aluminum alloy cannot be directly welded with the side frame after being melted by laser welding, so that a welding gap is formed at the welding position between the end plate and the side frame, welding wires are filled in the welding gap during welding, and the end plate and the side frame are connected together by melting the welding wires.

Therefore, through the mode, the safety and the reliability of the battery pack can be ensured on the basis of reducing the cost of the shell.

In one embodiment, the welding notch is formed in the end plate.

In one embodiment, the end plate comprises:

An outer surface and an inner surface disposed opposite the first direction, the inner surface being opposite the side frame;

An outer annulus between the outer surface and the inner surface connecting the outer surface and the inner surface;

The welding notch is formed in the joint of the inner surface and the outer ring surface and extends along the circumferential direction of the end plate.

In an embodiment, the end plate is a rectangular end plate, the outer ring surface is composed of four side surfaces, and the side frames are rectangular frames; the welding notches are four, and the four welding notches are respectively positioned on the four side surfaces;

and/or, the end plate further comprises an inner frame, wherein the inner frame is arranged on the inner surface and is coaxial with the axis of the end plate, and the inner frame extends from the inner surface along the first direction towards the direction away from the inner surface; the inner frame is positioned on the radial inner side of the side frame and is mutually propped against the inner annular surface of the side frame.

In one embodiment, the width of the welding notch is 1mm to 1.5mm, and the depth of the welding notch is 1.3mm to 1.8mm.

In one embodiment, the side frames are machined.

The invention also provides a manufacturing method of the shell based on the battery pack, which comprises the following steps:

Preparing a pair of end plates and side frames, wherein the end plates are oppositely arranged at two sides of the side frames along the first direction, and the side frames are sealed;

And welding the side frames with the pair of end plates in a laser filler wire welding mode, wherein welding wires are filled in the welding gaps during welding.

In one embodiment, in the laser welding, the laser beam is continuous wave, the wavelength is 1064nm, the laser power is 2600-28000 w, the welding speed is 31mm/s, the welding frequency is 250HZ, and the swing amplitude of the laser head is 0.9-1.0 mm; the wire feed speed was 1.9m/min.

In one embodiment, when the top parts of the end plate and the side frame are welded in a laser welding mode, the laser power is 2600w, the welding speed is 31mm/s, and the swing amplitude is 0.9mm;

and/or when the side edges and the bottoms of the end plates and the side frames are welded in a laser welding mode, the laser power is 2600w, the welding speed is 31mm/s, the wire feeding speed is 1.9m/min, the welding frequency is 250HZ, and the swing amplitude of the laser head is 0.9mm.

In one embodiment, before the step of welding the side frames to the pair of end plates by using a laser filler wire welding method, the welding position is cleaned, and the cleaning effect is detected by using a surface cleaner.

Drawings

One or more embodiments are illustrated by way of example and not limitation in the figures of the accompanying drawings, in which like references indicate similar elements, and in which the figures of the drawings are not to be taken in a limiting sense, unless otherwise indicated.

FIG. 1 is a schematic view of a housing in an embodiment of the present invention;

FIG. 2 is a top view of FIG. 1;

FIG. 3 is a cross-sectional view taken along the direction A-A in FIG. 2;

Fig. 4 is a left side view of fig. 1.

Reference numerals illustrate:

1. An end plate; 11. an outer surface; 12. an inner surface; 13. an outer annulus; 14. an inner frame; 2. a side frame; 21. a cover plate; 22. a U-shaped housing; 221. a sidewall; 222. a bottom plate; 3. and welding the notch.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the embodiments of the present application more apparent, the following detailed description of the embodiments of the present application will be given with reference to the accompanying drawings. However, those of ordinary skill in the art will understand that in various embodiments of the present application, numerous technical details have been set forth in order to provide a better understanding of the present application. The claimed application may be practiced without these specific details and with various changes and modifications based on the following embodiments.

In the following description, for the purposes of explanation of various disclosed embodiments, certain specific details are set forth in order to provide a thorough understanding of the various disclosed embodiments. One skilled in the relevant art will recognize, however, that an embodiment may be practiced without one or more of the specific details. In other instances, well-known devices, structures, and techniques associated with the present application may not be shown or described in detail to avoid unnecessarily obscuring the description of the embodiments.

Throughout the specification and claims, unless the context requires otherwise, the word "comprise" and variations such as "comprises" and "comprising" will be understood to be open-ended, meaning of inclusion, i.e. to be interpreted to mean "including, but not limited to.

The following detailed description of various embodiments of the present invention will be provided in connection with the accompanying drawings to provide a clearer understanding of the objects, features and advantages of the present invention. It should be understood that the embodiments shown in the drawings are not intended to limit the scope of the invention, but rather are merely illustrative of the true spirit of the invention.

Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

As used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. It should be noted that the term "or" is generally employed in its sense including "and/or" unless the context clearly dictates otherwise.

In the following description, for the purposes of clarity of presentation of the structure and manner of operation of the present invention, the description will be made with the aid of directional terms, but such terms as "forward," "rearward," "left," "right," "outward," "inner," "outward," "inward," "upper," "lower," etc. are to be construed as convenience, and are not to be limiting.

Hereinafter, a case of a battery pack according to a first embodiment of the present invention will be described with reference to the accompanying drawings, the case of the battery pack including: a pair of end plates 1 and side frames 2, the pair of end plates 1 being disposed opposite each other in the first direction, and the end plates 1 being as-cast aluminum alloy end plates 1, that is, the end plates 1 being cast from an aluminum alloy.

In addition, as shown in the drawing, the axis of the side frame 2 is disposed along the first direction, the side frame 2 is disposed between the pair of end plates 1, and both ends of the side frame 2 along the first direction are respectively welded to the first pair of end plates 1.

In addition, in order to facilitate the welding of the end plate 1 and the side frame 2 together, a welding notch 3 is formed at the welding position between the end plate 1 and the side frame 2, and welding wires can be filled in the welding notch 3 during welding.

Because the end plate 1 of the shell is an as-cast aluminum alloy end plate 1, that is to say, the end plate 1 is formed by casting of aluminum alloy, the manufacturing cost of the end plate 1 is very low because the casting process is simple, and the price of one end plate 1 is about ten yuan, so that the cost can be effectively saved.

However, the inventor found that the end plate 1 cast from aluminum alloy cannot be directly welded to the side frame 2 by laser welding after being melted, and therefore, in the present application, a welding notch 3 is formed at the welding position between the end plate 1 and the side frame 2, and welding wires are filled in the welding notch 3 during welding, so that the end plate 1 and the side frame 2 are connected together by melting the welding wires.

Specifically, in the present embodiment, the welding notch 3 is formed on the end plate 1, and of course, in some embodiments, the welding notch 3 may also be formed on the side frame 2.

In the present embodiment, as shown in the figure, the end plate 1 includes: the outer surface 11, the inner surface 12, and the outer ring surface 13 connecting the outer surface 11 and the inner surface 12, the outer surface 11 and the inner surface 12 being disposed opposite each other in the first direction, the inner surface 12 being opposite the side frame 2. An outer annulus 13 is located between the inner surface 12 and the outer surface 11, connecting the inner surface 12 and the outer surface 11. The joint of the inner surface 12 and the outer ring surface 13 is provided with a welding notch 3, and the welding notch 3 extends along the circumferential direction of the end plate 1.

Specifically, in the present embodiment, as shown in the drawing, the end plate 1 is a rectangular end plate 1, the outer ring surface 13 is composed of four side surfaces, and the side frame 2 is a rectangular frame. As shown in the figure, the number of the welding notches 3 is four, the four welding notches 3 are respectively positioned on four sides, and meanwhile, each welding notch 3 is a strip-shaped notch.

Preferably, the width of the welding notch 3 is 1mm to 1.5mm, and the welding effect is best when the depth of the welding notch 3 is 1.3mm to 1.8 mm.

Additionally, as shown, in some embodiments, the end plate 1 may further include an inner frame 14, where the inner frame 14 is located on the inner surface 12, and an axis of the inner frame 14 is coaxial with an axis of the end plate 1, where the inner frame 14 extends from the inner surface 12 in a first direction away from the inner surface 12, and as shown, the inner frame 14 is disposed radially inward of the side frame 2 and abuts against an inner annular surface of the side frame 2.

In addition, the battery pack includes a plurality of battery modules disposed in the case, and each battery module is disposed in the case in parallel along the first direction.

In addition, as shown in the figure, the side frame 2 includes a cover plate 21 and a U-shaped housing 22, the cover plate 21 is covered on the U-shaped housing 22 to form a rectangular side frame 2, and the cover plate 21 and the U-shaped housing 22 are welded with the end plate 1 respectively. The U-shaped housing 22 has two oppositely disposed side walls 221 and a bottom plate 222 disposed opposite the cover plate 21.

In the actual welding process, a pair of end plates 1 are oppositely arranged on two sides of a side frame 2, the positions between the side frame 2 and the pair of end plates 1 can be fixed by adopting a clamp, then the side frame 2 and the pair of end plates 1 are welded together by adopting a laser filler wire welding mode, welding wires are filled in welding gaps 3 in the welding process, and after the welding wires are melted, the side frame 2 and the end plates 1 can be connected together. Since the welding wire is filled in the welding gap 3, the connection surface between the side frame 2 and the end plate 1 is still flat.

In addition, preferably, the side frame 2 is formed by machining, and since the side frame 2 is formed by machining, the surface of the side frame 2 is flat and burr-free, and when laser welding is adopted, light can be reflected by the flat surface, so that the side frame 2 can be prevented from being melted, and the welding effect can be improved.

A second embodiment of the present invention provides a method for manufacturing a case of a battery pack in the first embodiment, specifically including the steps of:

firstly, preparing a pair of end plates 1 and side frames 2, wherein the end plates 1 are oppositely arranged on two sides of the side frames 2 along a first direction, and the side frames 2 are closed;

And then, welding the side frame 2 and the pair of end plates 1 by adopting a laser filler wire welding mode, wherein welding wires are filled in the welding notch 3 during welding.

In the laser welding, the laser beam is continuous wave, the wavelength is 1064nm, the laser power is 2600-28000 w, the welding speed is 31mm/s, the welding frequency is 250HZ, and the swing amplitude of the laser head is 0.9-1.0 mm; the wire feed speed was 1.9m/min.

In the welding process, protective gas is conveyed to the welding position to protect the welding seam from oxidation. Preferably, the delivery of the shielding gas to the welding location is started simultaneously with the emission of the laser beam to the welding location. Preferably, the shielding gas is nitrogen, and the flow rate of the nitrogen gas stream is 35L/min.

The laser welding technique is a high-energy density and high-precision welding method, and the welding heat source is a high-energy density laser beam. Laser deep-melting welding is generally performed by adopting a continuous laser beam, and the energy conversion mechanism of the metallurgical physical process is completed through a 'small hole' (Key-hole) structure. Under sufficiently high power density laser irradiation, the material evaporates and small holes are formed. The small hole filled with steam is like a black body, almost absorbs the whole energy of the incident laser beam, the small hole is filled with high-temperature steam generated by continuous evaporation of wall materials under the irradiation of the laser beam, the four walls of the small hole surround molten metal, the periphery of liquid metal surrounds solid materials, and the liquid flow outside the hole wall and the surface tension of the wall layer are maintained in dynamic balance with the steam pressure continuously generated in the hole cavity. The light beam continuously enters the small hole, the material outside the small hole continuously flows, and the small hole is always in a flowing stable state along with the movement of the light beam. The molten metal fills the void left by the removal of the keyhole and condenses therewith, and a weld is formed. When the power density is more than 105-107w/cm < 2 >, the metal surface is concave into a 'keyhole' under the action of heating to form deep fusion welding, the laser filler wire welding refers to a method of filling a specific welding material into a welding line, and then using laser irradiation to melt or filling the welding material into the welding line while the laser irradiation is performed to form a welding joint, so that the problems of processing a workpiece and excessively strict assembly requirements are avoided, and more importantly, the composition structure and performance of the welding line metal can be changed and controlled by changing the composition of the filler wire material.

In the field of lithium battery production, the structural design of the module shell plays an extremely critical role in the safety and reliability of the whole lithium battery manufacturing process. In general, since an as-cast aluminum alloy is formed by casting, it has defects such as coarse crystal grains and a large number of pores, and is not suitable for welding by directly melting the end plate 1 with laser light. In the invention, after the laser filler wire welding mode is adopted, the welding wire has high-quality chemical components, so that the performance of an as-cast structure can be improved, a good welding effect is achieved, the scheme that the as-cast aluminum alloy end plate replaces a machined end plate is successfully realized, and the material cost is greatly saved.

Preferably, the cover plate 21 in the side frame 2 is 6063 aluminum alloy, the U-shaped shell 22 is 5083 aluminum alloy, the clearance a between the end plate 1 and the side plate is smaller than or equal to 0.1mm, the smaller the clearance is, the more beneficial to improving the effect of fiber laser welding, and when the clearance is smaller, slag can be prevented from falling into the battery.

According to the laser filler wire welding method for the as-cast aluminum alloy shell, the welding starting power and the welding stopping power change along with the change of the wire feeding speed, when the wire feeding speed is high, the welding power also increases, and otherwise, the welding power is opposite.

In the welding process, the laser beam is perpendicular to the welding surface of the welding position, and the optical fiber laser adopted in the laser welding is arranged on the robot arm, so that the optical fiber laser can freely move and rotate, and automatic control is realized, so that the welding efficiency and the welding precision are improved.

The embodiment further comprises the step of cleaning dirt such as greasy dirt near the welding position before welding, and the cleaning effect is detected by adopting a surface cleanliness meter. For example, dirt around the welding position is cleaned, so that reflection of laser by the dirt is reduced, laser absorptivity of the welding position is increased, penetration is increased, and welding quality is guaranteed.

When the end plate 1 and the cover plate 21 are welded, namely, the top parts of the end plate 1 and the side frames 2 are welded in a laser welding mode, the spot diameter of the laser welding is 0.3mm, the shielding gas is nitrogen, and the flow rate of the nitrogen gas is 35L/min. The process data obtained in practice are as follows:

1) When the laser power of welding is 2700w, the welding speed is 31mm/s and the swing amplitude is 1.0mm, only the phenomenon of edge melting appears around the obtained welding line, and the welding effect cannot be achieved.

2) When the welding laser power is 2800w, the welding speed is 31mm/s and the swing amplitude is 0.9mm, the obtained weld back has slight penetration phenomenon, and the welding effect cannot be achieved.

3) When the laser power of the first welding is 2600w, the welding speed is 31mm/s, and the swing amplitude is 0.9mm, the obtained average penetration is 1.92mm, the average unit tensile force is 269.6N/mm, and the welding effect is optimal.

When the end plate 1 is welded with the U-shaped shell 22, namely, the side edges and the bottom of the end plate 1 and the side frames 2 are welded in a laser welding mode, the diameter of a light spot is 0.3mm, the shielding gas is nitrogen, and the flow rate of the nitrogen gas is 35L/min. The process data obtained in practice are as follows:

When the welding laser power is 2600w, the welding speed is 31mm/s and the swing amplitude is 0.9mm, the obtained penetration is 2.03mm, the unit tensile force is 325N/mm, and the welding effect is optimal.

From the data, when the welding laser power is 2600w, the welding speed is 31mm/s, the wire feeding speed is 1.9m/min, the welding frequency is 250HZ, the welding head swing amplitude is 0.9mm, the obtained penetration depth is 2.02mm, the welding seam is formed attractive, and the welding wire is full after welding, so that the strength completely meets the requirements.

The laser filler wire welding method for the as-cast aluminum alloy shell has the beneficial effects that: compared with the welding crack defect in the existing module shell laser welding method, the invention can realize the problem of as-cast aluminum alloy laser welding. And the complexity of the battery in the aspect of structural design is reduced, and the design cost and the manufacturing cost are reduced.

While the preferred embodiments of the present invention have been described in detail above, it should be understood that aspects of the embodiments can be modified, if necessary, to employ aspects, features and concepts of the various patents, applications and publications to provide yet further embodiments.

These and other changes can be made to the embodiments in light of the above detailed description. In general, in the claims, the terms used should not be construed to be limited to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled.

The above steps of the methods are divided, for clarity of description, and may be combined into one step or split into multiple steps when implemented, so long as they include the same logic relationship, and they are all within the protection scope of this patent; it is within the scope of this patent to add insignificant modifications to the algorithm or flow or introduce insignificant designs, but not to alter the core design of its algorithm and flow.

It is to be appreciated that, in the foregoing embodiments, there is a connection, and the related technical details mentioned in one embodiment are still valid in other implementations, so that the description is omitted to reduce repetition.

It will be understood by those of ordinary skill in the art that the foregoing embodiments are specific examples of carrying out the invention and that various changes in form and details may be made therein without departing from the spirit and scope of the invention.

Claims

1.A housing for a battery pack, the housing comprising:

a welding notch is formed at a welding position between the end plate and the side frame, and welding wires are filled in the welding notch;

the welding notch is formed in the end plate;

the end plate includes:

The welding notch is formed in the joint of the inner surface and the outer ring surface and extends along the circumferential direction of the end plate;

The end plate further comprises an inner frame located on the inner surface and coaxially arranged with the axis of the end plate, the inner frame extending from the inner surface in the first direction away from the inner surface; the inner frame is positioned on the radial inner side of the side frame and is mutually propped against the inner annular surface of the side frame;

the inner surface is propped against the end face of the side frame; each welding notch is a strip notch; the width of the welding notch is 1mm to 1.5mm, and the depth of the welding notch is 1.3mm to 1.8mm.

2. The case of the battery pack according to claim 1, wherein the end plate is a rectangular end plate, the outer ring surface is composed of four side surfaces, and the side frames are rectangular frames; the welding notches are four, and the four welding notches are respectively positioned on the four side faces.

3. The battery pack housing of claim 1 wherein the side frames are machined.

4. A method of manufacturing a case based on the battery pack according to any one of claims 1 to 3, comprising the steps of:

5. The method of manufacturing a case of a battery pack according to claim 4, wherein in the laser welding, the laser beam is continuous wave, the wavelength is 1064nm, the laser power is 2600w-28000w, the welding speed is 31mm/s, the welding frequency is 250HZ, and the swing amplitude of the laser head is 0.9mm-1.0mm; the wire feed speed was 1.9m/min.

6. The method of manufacturing a case of a battery pack according to claim 5, wherein when the end plate and the top of the side frame are welded by laser welding, the laser power is 2600w, the welding speed is 31mm/s, and the swing amplitude is 0.9 mm;

7. The method of manufacturing a case of a battery pack according to claim 4, wherein before the step of welding the side frames to the pair of end plates by laser filler wire welding, the welding position is cleaned and the cleaning effect is detected by a surface cleaner.