CN106329030B

CN106329030B - Cooling plate

Info

Publication number: CN106329030B
Application number: CN201510374735.5A
Authority: CN
Inventors: 郑卫鑫; 曾毅; 朱建华; 朱燕
Original assignee: BYD Co Ltd
Current assignee: BYD Co Ltd
Priority date: 2015-06-30
Filing date: 2015-06-30
Publication date: 2021-06-18
Anticipated expiration: 2035-06-30
Also published as: CN106329030A

Abstract

The invention discloses a cooling plate which comprises a heat-conducting plate and a cooling pipe, wherein the cooling pipe comprises a heat dissipation part arranged in the heat-conducting plate, an inlet part positioned at one end of the heat dissipation part and an outlet part positioned at the other end of the heat dissipation part, and the heat dissipation part is an integrated pipeline. According to the cooling plate provided by the invention, the heat dissipation part in the heat conduction plate is an integrated pipeline, the cooling liquid flows in the cooling pipe of the cooling plate, the heat dissipation part of the cooling pipe is an integrated pipeline without a welding edge, the cooling liquid cannot contact with welding solder, the sealing performance of the cooling pipe cannot be influenced or the cooling pipe cannot leak due to the corrosion of the solder, and the cooling pipe is strong in corrosion resistance and high in sealing reliability.

Description

Cooling plate

Technical Field

The invention relates to the field of cooling and heat dissipation of lithium ion battery modules, and mainly relates to a cooling plate.

Background

Lithium ion secondary batteries have become the primary power source for portable electronic devices because of their advantages of light weight, small size, no pollution, low internal pressure, low cost, etc. In the use process of the battery, under the conditions of short circuit, large-current charge and discharge and the like, a large amount of heat can be generated inside the battery module, and if the heat is not dissipated in time, the service performance, particularly the safety performance, of the battery module can be greatly influenced. In the power battery used for the vehicle, attention needs to be paid to the safety performance of the battery; therefore, through the design of the heat dissipation structure in the battery module, in the use process of the battery module or under the extreme condition, the heat in the battery module can be timely dissipated, and the direction of key research is needed in the manufacturing and using of the power battery.

In the common heat dissipation scheme in the prior art, two layers of metal plates are butted to form a cooling plate; as shown in fig. 1 and 2, the cooling plate 1 includes an upper metal plate 11 and a lower metal plate 12, a cooling groove 21 is provided on at least one of the upper metal plate 11 or the lower metal plate 12 (as shown in fig. 2, the cooling groove 21 is provided on the lower metal plate 12), and then the upper metal plate 11 and the lower metal plate 12 are fixedly joined together by brazing, and the cooling groove 21 is sealed between the upper metal plate 11 and the lower metal plate 12 to form a sealed cooling passage for a cooling liquid to flow. In the technical scheme, the inlet and the outlet of the cooling channel are required to be externally connected with a pipeline and are required to be welded and sealed.

Among the above-mentioned technical scheme, the brazed joint face overlength between upper metal sheet 11 and the lower metal sheet 12 to also weld between cooling channel and import and the export, in the use, the welding department is corroded by the coolant liquid that circulates among them easily, and then the problem of weeping appears. Therefore, in the scheme, the service life of the cooling plate is limited, liquid leakage is easy to occur after the cooling plate is corroded, and the liquid flows into the battery module, so that the battery module is easy to be damaged, and the service life of the battery module is shortened; moreover, leakage not only causes poor heat dissipation effect, but also affects the safety performance of the battery module.

Disclosure of Invention

The present invention aims to solve the above technical problem at least to some extent.

One object of the present invention is to provide a cooling pipe and a cooling plate which are free from corrosion and leakage and have high safety.

In order to solve the technical problem, the invention provides a cooling plate, which comprises a heat conducting plate and a cooling pipe, wherein the cooling pipe comprises a heat dissipation part arranged in the heat conducting plate, an inlet part positioned at one end of the heat dissipation part and an outlet part positioned at the other end of the heat dissipation part, and the heat dissipation part is an integrated pipeline.

According to the cooling plate provided by the invention, the heat dissipation part in the heat conduction plate is an integrated pipeline, the cooling liquid flows in the cooling pipe of the cooling plate, the heat dissipation part of the cooling pipe is an integrated pipeline without a welding edge, the cooling liquid cannot contact with welding solder, the sealing performance of the cooling pipe cannot be influenced or the cooling pipe cannot leak due to the corrosion of the solder, and the cooling pipe is strong in corrosion resistance and high in sealing reliability. Meanwhile, the possibility of liquid leakage is reduced, and the service life of the cooling plate is prolonged; and the safety performance of the battery cannot be adversely affected by leakage, and the battery module using the cooling plate has high safety performance.

Preferably, the heat dissipating portion, the inlet portion and the outlet portion are integrally formed pipes.

Preferably, the heat dissipation part is a flat pipe.

Further, the heat dissipation part is formed by flattening a circular tube.

Preferably, the cooling tube is welded or stuck in the heat conducting plate.

Preferably, the heat conducting plate is a flat plate.

Preferably, the heat dissipation part is bent a plurality of times within the heat conductive plate.

Further, the heat dissipation part is U-shaped or W-shaped.

Preferably, the orifice of the heat dissipation part is oval or rectangular.

Preferably, the ratio of the width of the heat dissipation part to the diameter of the round tube before flattening is 1.2-2.

Furthermore, the ratio of the width of the heat dissipation part to the diameter of the round tube before flattening is 1.4-1.8.

Preferably, the heat conducting plate is provided with a heat radiating portion mounting groove, and the heat radiating portion of the cooling pipe is mounted in the heat radiating portion mounting groove.

Further, the heat-conducting plate includes body and plate cover, the setting of radiating part mounting groove is on the body, plate cover and body fixed connection will radiating part mounting groove encapsulation is between plate cover and body.

Further, the heat dissipation part is welded or adhered in the heat dissipation part installation groove.

Further, the heat dissipation portion mounting groove is bent multiple times in the heat conductive plate.

Further, the heat dissipation part mounting groove is U-shaped or W-shaped.

Preferably, the heat dissipation part installation groove is composed of reinforcing ribs arranged on the cooling plate and a groove positioned between two adjacent reinforcing ribs.

Furthermore, the inner side wall of the heat dissipation part mounting groove is provided with a limiting groove, and the heat dissipation part is clamped in the heat dissipation part mounting groove through the limiting groove.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

fig. 1 is a schematic view of the overall structure of a cooling plate in the prior art.

Fig. 2 is an exploded view of a prior art cooling plate structure.

Fig. 3 is a schematic view showing the overall structure of a cooling plate according to an embodiment of the present invention.

FIG. 4 is a schematic view of a cooling tube structure prior to collapsing in one embodiment of the invention.

FIG. 5 is a schematic view of a flattened cooling tube structure according to an embodiment of the present invention.

Fig. 6 is a schematic view of the combination of a cooling tube and a thermally conductive plate in one embodiment of the invention.

Fig. 7 is a schematic cross-sectional view of a thermally conductive plate body in another embodiment of the invention.

FIG. 8 is a schematic view of a bent cooling tube structure according to an embodiment of the present invention.

Reference numerals: 1. a heat conducting plate; 11. an upper metal plate; 12. a lower metal plate; 13. a heat dissipation part mounting groove; 131. reinforcing ribs; 132. a limiting groove; 14. a body; 15. a plate cover; 2. a cooling tube; 21. cooling the groove; 22. an inlet section; 23. an outlet portion; 24. a heat dissipating portion.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.

In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate orientations or positional relationships based on those shown in the drawings, and are used merely for convenience of description and for simplicity of description, and do not indicate or imply that the device or element so referred to must have a particular orientation, be constructed in a particular orientation, and be operated, and thus should not be considered as limiting the present invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.

In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

The cooling plate provided by the present invention is described with reference to fig. 3 and 4, and includes a heat-conducting plate 1 and a cooling tube 2, wherein the cooling tube 2 includes a heat-dissipating portion 24 disposed in the heat-conducting plate 1, an inlet portion 22 located at one end of the heat-dissipating portion 24, and an outlet portion 23 located at the other end of the heat-dissipating portion 24, and the heat-dissipating portion 24 is an integrated pipe. The heat dissipation part 24 is disposed inside the heat conduction plate 1, and the heat collected by the heat conduction plate 1 is taken away by the coolant flowing through the heat dissipation part 24 through the contact between the heat dissipation part 24 and the heat conduction plate 1, so as to achieve the purpose of cooling and lowering the temperature. In the present invention, as shown in fig. 3 and 4, the inlet portion 22 and the outlet portion 23 are respectively located at both ends of the heat radiating portion 24. Here, the inlet portion 22 and the outlet portion 23 refer to interfaces at the end portions of the heat conductive plate 1 for introducing the cooling liquid into the heat radiating portion 24 or for leading the cooling liquid out of the heat radiating portion 24. The inlet section 22 and outlet section 23 are simply references to the conduits at the ends of the plate 1 and are not intended to be limited in their construction and location. As shown in fig. 3, the inlet portion 22 and the outlet portion 23 may be located on the same side of the plate 1, only one of which is illustrated in the figures for one embodiment; furthermore, it is possible that the inlet portion 22 and the outlet portion 23 are also located on different sides of the plate 1, for example on opposite sides of the plate 1 or on adjacent sides of the plate 1, without limiting the invention.

And the heat dissipation part is 24 integrated pipelines. The one-piece pipe is a commonly-used one-piece pipe, and the heat dissipation portion 24 is made of a complete metal pipe or other pipe made of insulating heat-conducting material, without welding or other mechanical connection. In one embodiment, as shown in fig. 4, the heat dissipation portion 24 is formed by bending a complete pipe, and both ends of the pipe are hermetically connected to the inlet portion 22 and the outlet portion 23. In the present invention, the heat dissipation portion 24, the inlet portion 22 and the outlet portion 23 are artificially divided to better describe the technical solution and the technical effect of the present invention. In fact, the heat dissipating section 24, the inlet section 22 and the outlet section 23, if taken separately, are all one complete pipe; or three sections of a complete pipe.

The cooling plate provided by the invention has the advantages that the heat dissipation part 24 positioned in the heat conduction plate 1 is an integrated pipeline, the cooling liquid flows in the cooling pipe 2 of the cooling plate, the heat dissipation part 24 of the cooling pipe 2 is an integrated pipeline without a welding edge, the cooling liquid cannot contact with welding solder, the sealing performance of the cooling pipe 2 cannot be influenced or liquid leakage cannot occur due to corrosion of the solder, and the cooling pipe 2 is strong in corrosion resistance and high in sealing reliability. Meanwhile, the possibility of liquid leakage is reduced, and the service life of the cooling plate is prolonged; and the safety performance of the battery cannot be adversely affected by leakage, so that the safety performance of the battery module using the cooling plate is high.

In one embodiment of the present invention, the cooling pipe 2 is an integrated pipe, and the heat dissipation portion 24, the inlet portion 22 and the outlet portion 23 are all part of the integrated pipe. As shown in fig. 4, a complete pipe (a single pipe, which may be a metal pipe or other pipe made of insulating and heat-conducting material) is bent and then formed, and the complete pipe is bent and includes a heat dissipation portion 24, an inlet portion 22 and an outlet portion 23. In this way, when the cooling pipe 2 is manufactured, a complete pipeline (such as a metal pipe) can be directly bent to manufacture the cooling pipe 2; in this process, the production is simple and no welding or mechanical connection to the cooling tube 2 is made. Therefore, the heat radiating portion 24 does not have any welding mark, and the heat radiating portion 24 and the inlet portion 22, the heat radiating portion 24 and the outlet portion 23, and the inlet portion 22 and the outlet portion 23 do not have any welding mark. Therefore, the coolant in the cooling pipe 2 does not corrode the heat dissipation part 24, and does not corrode the inlet part 22, the outlet part 23 and the joint of the heat dissipation part 24 and the inlet part 22 and the outlet part 23, thereby further improving the corrosion resistance and the sealing reliability of the cooling pipe, reducing the possibility of liquid leakage and improving the safety performance of a battery module using the cooling plate.

As shown in fig. 5, in one embodiment of the present invention, the heat dissipating parts 24 are flat tubes. The flat pipe has been utilized here to have two broad surfaces, makes radiating part 24 can the bigger area contact with heat-conducting plate 1 for heat in heat-conducting plate 1 more easily penetrate cooling tube 2 through radiating part 24 inside, is taken away by the coolant liquid, plays better radiating effect.

Still further, in another embodiment of the present invention, the heat dissipation portion 24 is formed by flattening a circular tube. During the flattening process of the circular tube, the flattening thickness of the circular tube can be manually controlled; in addition, in the manufacturing process, the heat dissipation portion 24 may be placed in the heat conductive plate 1, and the heat conductive plate 1 may be pressed to obtain the flattened heat dissipation portion 24.

In one embodiment of the invention, the cooling tube 2 is welded or glued into the heat-conducting plate 1. More finely, the heat dissipation portion 24 is welded or adhered to the heat conductive plate 1.

The heat dissipation portion 24 or the flat tube is preferably made of a material with good thermal conductivity and ductility, such as aluminum and aluminum alloy, copper and copper alloy, high thermal conductivity polymer material, magnesium aluminum alloy, and the like. The material of the outer heat-conducting plate 1 is preferably a material having good thermal conductivity and strength, such as aluminum and aluminum alloy, copper and copper alloy, high thermal conductivity polymer material, magnesium aluminum alloy, and the like.

In one embodiment of the invention, the thermally conductive plate 1 is a flat plate, as shown in fig. 3. The flat plate is arranged for better adhering to the surrounding structure needing cooling, so that the function of heat conduction is better realized. Further, the presence of the flat plate enables the heat conductive plate 1 to be in better contact with the heat radiating portion 24 in the shape of a flat tube. Of course, the heat-conducting plate 1 can also be designed to match the L-shape or the groove if the external structure has some special shape, such as L-shape, groove on the surface, etc., in order to better match the structure that needs to be cooled.

In one embodiment of the present invention, as shown in fig. 5 or fig. 8, in order to make the cooling plate better perform the heat dissipation function, the heat dissipation part 24 may be selected to be bent multiple times in the heat conduction plate 1, and the multiple bending is a shape after the heat dissipation part 24 is arranged in the heat conduction plate 1; so as to increase the contact area of the heat dissipation part 24 and the heat conducting plate 1, thereby increasing the speed of transferring heat in the heat conducting plate 1 to the cooling pipe 2 and improving the heat dissipation performance of the cooling plate.

More preferably, in the present invention, the heat radiating portion 24 of the cooling pipe 2 may be U-shaped or W-shaped in the heat conductive plate 1. As shown in fig. 8, i.e., a W-shaped arrangement.

In one embodiment of the present invention, as shown in fig. 6, the orifice of the heat dissipating portion 24 is oval; of course, other shapes such as rectangular shapes are also possible. The oval pipe orifice can be directly formed by extruding a round pipe, so that the manufacturing is convenient; on the other hand, as will be shown in the following, the oval pipe orifice can be better in interference fit with the heat dissipation part installation groove 13, so that the connection between the cooling pipe 2 and the heat conduction plate 1 is firmer.

In the present invention, the ratio of the width of the heat dissipation portion, i.e., the width of the wide surface of the flat tube described above to the diameter of the round tube before flattening is 1.4 to 1.8. More preferably, the ratio may be selected to be in the range of 1.4-1.8. The proportion is provided on the premise of comprehensively considering the influence of the contact area and the flow velocity of the cooling liquid on the heat dissipation effect. Theoretically, the larger the contact area is, the faster the flow rate of the cooling liquid is, and the better the heat dissipation effect of the cooling plate is; however, in the actual structure, if the contact area is large, the heat radiating portion 24 is pressed to be flat, which inevitably affects the cross-sectional area of the liquid when the coolant flows through the cooling pipe, and the flow rate of the coolant is decreased as the cross-sectional area is smaller. Therefore, in order to take account of the contact area and the flow rate of the cooling liquid, the invention further designs the heat dissipation part 24 of the cooling pipe 2, and limits the ratio of the width of the heat dissipation part to the diameter of the circular pipe; on the premise of increasing the contact area as much as possible, the flow speed of the cooling liquid in the cooling pipe is ensured as much as possible.

As shown in fig. 6, in the cooling plate according to the present invention, the heat radiating portion mounting groove 13 is provided in the heat conducting plate 1, and the heat radiating portion 24 of the cooling pipe 2 is mounted in the heat radiating portion mounting groove 13. That is, a groove for prepositioning or placing the heat dissipation part 24 of the cooling tube 2 is formed in the heat conducting plate 1, and in the process of manufacturing the cooling plate, the heat dissipation part 24 of the cooling tube 2 can be placed in the heat dissipation part mounting groove 13 in advance to be prepositioned, so that subsequent connection or flattening operation is facilitated. The heat dissipation part mounting groove 13 may be a groove recessed in the cooling plate, or a heat dissipation part mounting groove may be formed by providing a protruding member on the cooling plate and forming two adjacent protruding members and a groove therebetween.

Further, the heat conducting plate 1 includes a body 14 and a plate cover (not shown), and the heat dissipating part mounting groove 13 is provided on the body 14, and then the heat dissipating part mounting groove 13 is enclosed between the plate cover and the body 14 by the fitting and fixing connection of the body 14 and the plate cover. While also enclosing the cooling tubes 2 between the body 14 and the plate cover. Sealing the heat-conducting plate and dissipating heat.

As described above, the heat dissipation portion 24 of the cooling pipe 2 is welded or adhered to the heat dissipation portion mounting groove 13.

In order to cooperate with the heat dissipation portion 24 to be arranged in the heat conduction plate 1 in a multi-bending manner or in a U-shaped or W-shaped manner, the heat dissipation portion mounting groove 13 is also arranged in a multi-bending manner or in a U-shaped or W-shaped manner.

In one embodiment of the present invention, the heat dissipation part installation groove 13 is composed of ribs 131 provided on the cooling plate and a groove between two adjacent ribs 131. As shown in fig. 6, two ribs 131 protruding upward are provided on the body 14, and the two ribs jointly form a heat dissipation portion mounting groove. The provision of the ribs 131 as shown improves the overall strength of the cooling plate. In the invention, the cooling plate with two sealed end surfaces can be adopted, or the cooling plate with one sealed end surface can be adopted; when a cooling plate with one sealed side is used, the body 14 in fig. 6 can be regarded as a plate body of the whole cooling plate; when a cooling plate sealed on both sides is used, only the structure of the body 14 and the heat sink installation grooves provided on the body 14 is shown in fig. 6. In summary, fig. 6 is only one preferred embodiment of the present invention. In fig. 6, two ribs 131 are provided on the body 14, the heat dissipation portion mounting recess 13 is formed by the two ribs 131, and the final cooling plate is formed by covering the body 14 with a plate cover (not shown). The reinforcing ribs 131 are actually protrusions provided on the cooling plate to be higher than the surface of the cooling plate, and serve to form the heat dissipation portion mounting grooves and reinforce the cooling plate.

In another embodiment of the present invention, as shown in fig. 7, a limiting groove 132 is disposed on an inner side wall of the heat dissipation portion mounting groove 13, and the heat dissipation portion 24 is clamped in the heat dissipation portion mounting groove 13 through the limiting groove 132. No matter the heat dissipation part installation groove 13 is sunken inside the cooling plate or is composed of reinforcing ribs arranged on the surface of the cooling plate, the inner side wall of the heat dissipation part installation groove can be provided with the limiting groove 132 for limiting the heat dissipation part 24. The heat radiating portion 24 of the cooling pipe 2 is engaged with the inside of the limit groove 132. Here, the heat dissipation portion 24 is clamped in the heat dissipation portion mounting groove 13 by the interference fit, so that the subsequent processing and manufacturing and the stability of the cooling plate are facilitated.

Meanwhile, the invention also provides a lithium ion battery module, wherein a cooling plate is arranged in the lithium ion battery module, and the cooling plate is the cooling plate provided by the invention.

The lithium ion battery module provided by the invention has the advantages that the situations of liquid leakage or influence on the safety performance of the cooling pipe in the cooling plate due to corrosion can be avoided, and the cooling plate has higher sealing reliability and corrosion resistance and higher safety performance.

The invention also provides an automobile, wherein the automobile is provided with the lithium ion battery module, and the lithium ion battery module is the lithium ion battery module provided by the invention.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made in the above embodiments by those of ordinary skill in the art without departing from the principle and spirit of the present invention.

Claims

1. The cooling plate is characterized by comprising a heat-conducting plate and a cooling pipe, wherein the cooling pipe comprises a heat-radiating part arranged in the heat-conducting plate, an inlet part positioned at one end of the heat-radiating part and an outlet part positioned at the other end of the heat-radiating part, a heat-radiating part mounting groove is formed in the heat-conducting plate, the heat-radiating part mounting groove consists of reinforcing ribs arranged on the cooling plate and grooves positioned between two adjacent reinforcing ribs, the heat-radiating part of the cooling pipe is arranged in the heat-radiating part mounting groove, and the heat-radiating part is an integrated pipeline.

2. The cooling plate of claim 1, said heat sink portion, inlet portion and outlet portion being integrally formed tubes.

3. A cooling plate according to claim 1 or 2, wherein the heat sink portions are flat tubes.

4. A cooling plate as claimed in claim 1 or 2, wherein said heat dissipating portion is formed by flattening a circular tube.

5. A cooling plate as claimed in claim 1, wherein the cooling tubes are welded or glued within the thermally conductive plate.

6. The cooling plate of claim 1, wherein the thermally conductive plate is a flat plate.

7. A cooling plate as claimed in claim 1, wherein the heat sink portion is bent multiple times within the heat conductive plate.

8. A cooling plate as claimed in claim 6, wherein said heat sink portion is U-shaped or W-shaped.

9. A cooling plate according to claim 1, wherein the orifices of the heat dissipating sections are oval or rectangular.

10. A cooling plate as claimed in claim 4, wherein the ratio of the width of the heat dissipating portion to the diameter of the round tube before flattening is 1.2 to 2.

11. A cooling plate as claimed in claim 10, wherein the ratio of the width of the heat dissipating portion to the diameter of the round tube before flattening is 1.4 to 1.8.

12. The cooling plate as claimed in claim 1, wherein the heat conductive plate includes a body and a plate cover, the heat dissipating part mounting groove is provided on the body, the plate cover is fixedly connected with the body, and the heat dissipating part mounting groove is enclosed between the plate cover and the body.

13. A cooling plate as claimed in claim 1, wherein the heat dissipating part is welded or adhered to the heat dissipating part mounting groove.

14. A cooling plate as claimed in claim 1, wherein the heat radiating portion mounting groove is bent a plurality of times in the heat conductive plate.

15. A cooling plate as claimed in claim 14, wherein the heat sink mounting groove is U-shaped or W-shaped.

16. The cooling plate as claimed in claim 1, wherein a limiting groove is provided on an inner sidewall of the heat dissipating part mounting groove, and the heat dissipating part is engaged in the heat dissipating part mounting groove through the limiting groove.