KR102492180B1 - Battery module with enhanced cooling performance - Google Patents

Abstract

Disclosed is a battery module having enhanced cooling performance. The battery module having enhanced cooling performance according to the present invention is a battery module that receives and protects a battery unit where a plurality of battery cells are stacked in a transverse direction, which comprises: a cooling plate disposed below the battery unit to absorb heat generated from the battery cell through a cooling material supplied from the outside to flow therethrough; and a cooling spacer bonded to the cooling plate while interposed between the battery cells to mediate heat transfer to the cooling plate and extruded from a thermally conductive material to suppress the swelling of the battery cell. According to the present invention, the plurality of cooling spacers made of the thermally conductive material are bonded to the cooling plate while interposed respectively between the battery cells, so that heat emitted from both sides of the large-area battery cell can be quickly and efficiently transferred to the cooling plate to dissipate and the swelling phenomenon where the outer shell of the battery cell swells can be effectively suppressed. The cooling spacer integrally extruded without a separate assembling process is directly bonded to the cooling plate, so that a process of filling a gap with a filler can be omitted and the assembling process of the battery module can be simplified.

Description

Battery module with enhanced cooling performance {BATTERY MODULE WITH ENHANCED COOLING PERFORMANCE}

The present invention relates to a battery module having enhanced cooling performance, and more particularly, to a battery module provided with a cooling spacer disposed between battery cells and bonded to a cooling plate to promote heat transfer.

Secondary batteries that repeatedly store and supply electrical energy go beyond the field of conventional small and high-tech electronic devices such as mobile phones, PDAs, and notebook computers. ) or as a power source for hybrid electric vehicles (HEVs).

Secondary batteries widely used in current storage systems (ESS) or electric vehicles (EV) can be classified into lithium ion batteries, lithium polymer batteries, nickel cadmium batteries, nickel hydrogen batteries, nickel zinc batteries, etc. These secondary batteries is repeated charging and discharging with an output voltage of about 25V to 42V per unit battery cell.

At this time, when higher output voltage and power capacity are required, several battery cells are electrically connected to form a battery module, which is a low order group, or these battery modules are arranged in series or parallel again and connected, and other circuits are used. In addition, a battery pack, which is a large-scale assembly of high power, is constituted.

As described above, a battery module or battery pack composed of a plurality of battery cells with a high degree of integration manages heat caused by various causes such as repeated charging and discharging, overcharging or overdischarging, manufacturing defects, leaving at high temperatures, and external shocks. And, it is made up of a complex structure equipped with a system that safely stores and protects each battery cell from safety accidents such as fire or explosion, and integrally monitors and controls the state of charge, voltage, etc.

For example, Korean Patent Publication No. 10-2015-0142790 (published date: 2015.12.23) 'End plate for battery module assembly and battery pack including the same' is assembled in a box shape and produces a battery due to swelling. It has a basic configuration of a plurality of steel plate frames, sensing assemblies, and various circuit assemblies that prevent external changes of the module and reduce external impact.

However, such a conventional battery pack has a complicated assembly process in which the side strap 113 and the plurality of upper straps 114 are individually coupled to the first and second plates 111 and 112 supporting both sides of the battery module assembly 11, respectively. In view of the lack of specific means for effectively radiating or dissipating heat generated from a plurality of battery cells, research and development on ways to promote convenience in assembly work or efficient heat management are required. to be.

Republic of Korea Patent Publication No. 10-2015-0142790 (published date: 2015.12.23)

An object of the present invention is to quickly and efficiently perform cooling or thermal management of a plurality of battery cells seated on a cooling plate through which a cooling material flows without a gap filler (TIM, Thermal Interface Material) filled between the battery cells and the cooling plate. And, to provide a battery module having an enhanced cooling performance that can suppress the swelling of the battery cell.

The above object is a battery module that houses and protects a battery unit formed by stacking a plurality of battery cells in the horizontal direction, through a cooling material provided below the battery unit and supplied from the outside to flow inside the battery cell a cooling plate that absorbs heat generated from; and a cooling spacer disposed between the battery cells and bonded to the cooling plate to mediate heat transfer to the cooling plate and extruded from a thermally conductive material to suppress swelling of the battery cell. This is achieved by a battery module having a cooling performance.

The cooling spacer may include a central frame interposed between the battery cells so that side surfaces of the battery cells adjacent to each other are in surface contact with each other, and a hollow is formed therein; an upper frame extending from an upper end of the central frame to make surface contact with portions of the upper surface of the battery cells adjacent to each other; and lower frames extended from lower ends of the central frame and bonded to the cooling plate so as to make surface contact with portions of lower surfaces of the battery cells adjacent to each other.

The upper frame may include a plurality of heat dissipation fins that are spaced apart from each other on the upper surface of the upper frame and protrude upwardly along the extrusion direction in order to dissipate the heat of the battery cells transmitted to the central frame upward. .

The lower frame is extruded in a groove shape corresponding to the fastening protrusions on the lower surface of the lower frame so that the lower frame slides laterally with respect to a plurality of fastening protrusions protruding upward from the upper surface of the cooling plate. It may include a long recessed fastening groove along the.

A phase change material may be filled in the hollow to reduce heat transfer between adjacent battery cells and improve heat dissipation efficiency.

The hollow is divided into a plurality of pieces by one or more partition walls reinforcing the rigidity of the central frame, and the cooling material and the phase change material supplied through one side and discharged to the other side are respectively in different positions in the plurality of divided hollows. It can be alternately filled.

The battery module may further include an upper cover disposed to cover an upper surface of the battery unit and through-coupled to the heat dissipation fins so that the heat dissipation fins are cooled by a cooling material flowing through an internal passage.

According to the present invention, a cooling plate for absorbing heat generated in a battery unit in which a plurality of battery cells are stacked in a horizontal direction is provided below the battery unit, and a plurality of cooling spacers, which are thermally conductive materials, are disposed between the battery cells, respectively. As it is bonded to the cooling plate in this state, the heat emitted from both sides of the facing battery cell can be quickly and efficiently transferred to and dissipated to each cooling plate, and the swelling phenomenon in which the outer skin of the battery cell swells can be effectively suppressed. do.

In addition, as the cooling spacer made of thermally conductive material integrally extruded without a separate assembly process is directly bonded to the cooling plate to mediate heat transfer to the cooling plate, a gap filler (TIM, Thermal Interface Material) is formed between the battery cell and the cooling plate. ) can be omitted, and the assembly process of the battery module can be simplified.

1 is an exploded perspective view of a battery module having enhanced cooling performance according to an embodiment of the present invention.
FIG. 2 is a perspective view of a cooling spacer disposed between the battery cells of FIG. 1 .
3 is a front view of the cooling spacer of FIG. 2;
4 is an operating state diagram based on AA cross-sectional view of a battery module having enhanced cooling performance according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, in describing the present invention, descriptions of already known functions or configurations will be omitted to clarify the gist of the present invention.

1 is an exploded perspective view of a battery module having enhanced cooling performance according to an embodiment of the present invention, FIG. 2 is a perspective view of a cooling spacer disposed between battery cells of FIG. 1, and FIG. 3 is a cooling spacer of FIG. 4 is an operating state diagram based on an A-A cross-sectional view of a battery module having enhanced cooling performance according to an embodiment of the present invention.

Top (top), bottom (bottom), left and right (side or side), front (front, front), back (back, back), etc., which refer to directions in the description and claims of the invention, etc., are not intended to limit the use of rights. For convenience of description, the relative position between the drawings and configurations is determined as a standard, and the three axes may be rotated and changed to correspond to each other, and this is followed unless otherwise specifically defined.

The battery module 100 having enhanced cooling performance according to the present invention quickly and efficiently dissipates the heat emitted from both sides of the large-area battery cell 10 to the cooling plate 120 below, and the battery cell 10 ) It is an invention devised to effectively suppress the swelling phenomenon (swellg), while simplifying the assembly process of the battery module 100.

In order to specifically implement the functions or actions as described above, the battery module 100 according to the embodiment of the present invention, as shown in FIGS. 1 to 3, a plurality of battery cells 10 are horizontally It may include the battery unit 110, the side cover 20, the first and second brackets 30, the cooling plate 120, the cooling spacer 130, the upper cover 140, and the like, which are laminated.

Hereinafter, the above-described configurations will be described in detail.

First, the battery unit 110 is a component formed by stacking a plurality of pouch-type battery cells 10 such that both side surfaces of a large area are overlapped with each other in order to form a predetermined output voltage and power.

Here, the battery cell 10 includes a positive electrode plate and a negative electrode plate disposed with a separator in the electrolyte interposed therebetween, a lead tab 12 that is a protruding plate-shaped electrode that electrically connects the positive electrode plate and the negative electrode plate to an external bus bar 32, and an outer shell. It may be composed of a coating or the like that seals the battery cell 10.

As shown in FIG. 2 and the like, the lead tabs 12 may be formed at the front and rear, respectively, or may be formed together in any one of the front and rear directions, as shown.

Since the battery unit 110 as described above is merely a component obtained by stacking battery cells 10 that have already been known and commercialized in the horizontal direction and is not related to the gist of the present invention, a detailed description of the structure or operating characteristics thereof is not given. to omit

Between the plurality of battery cells 10 constituting the above-described battery unit 110, as will be described later, suppressing and supporting external changes due to swelling of the battery cells 10, and from both sides of the large-area battery cells 10 A cooling spacer 130 may be interposed to quickly and efficiently dissipate the heat dissipated to the cooling plate 120 below.

As shown in FIG. 1, the side cover 20 forms an inner space together with the first and second brackets 30, the cooling plate 120, and the upper cover 140 to protect the battery from external environment or impact. As a plate-shaped component that accommodates and protects the unit 110, both side surfaces of the battery module 100 are formed.

The side cover 20 according to the embodiment of the present invention is arranged to support both sides of the battery unit 110 in order to suppress swelling occurring in the direction in which the battery cells 10 are stacked, and the battery unit 110 For electrical insulation and heat dissipation, a multiple structure consisting of an end plate 22 and a shield plate 24 may be formed.

At this time, the end plate 22 is a plate-shaped component for smoothly transferring heat generated in accordance with the operation of the battery unit 110 from both side surfaces of the battery unit 110 to the outside, respectively, and is an aluminum alloy plate having excellent thermal conductivity. etc. to form the outside of the side cover 20, that is, the outside.

The shielding plate 24 is a plate-shaped component for contacting and insulating both sides of the battery unit 110 and transferring heat generated in the battery unit 110 to the above-described end plate 22, and has insulating properties. , Engineering plastic containing at least one of PPS, PEEK, TPI, PES, PPA, and PEI having excellent heat resistance, stiffness, and flame retardancy may be integrally molded by injecting into the end plate 22 inserted into the mold.

At this time, as described above, the engineering plastic constituting the shielding plate 24 may contain a powder such as graphene material or aluminum as a filler in order to realize excellent heat dissipation and rigidity.

The first and second brackets 30 are components in which a fixing groove into which the battery cell 10 is inserted may be formed, and a seating groove into which a bus bar 32 is mounted and fixed is formed on a surface opposite to the fixing groove. .

Here, the bus bar 32 is a conductor provided in plurality to be electrically connected to the lead tab 12 of the battery cell 10 described above and to stably transmit a high voltage output to the outside without loss, and is an external circuit. It may be manufactured in various shapes such as a bent bar shape for electrical connection with (not shown) or a ring shape for parallel connection of the battery cells 10 .

The bus bar 32 is electrically connected to the lead tab 12 when the first and second brackets 30 penetrated by the lead tab 12 of the battery cell 10 are coupled to the above-described side cover 20 or the like. It can be connected to and can be bound to the lead tab 12 by welding or the like.

The first and second brackets 30 according to an embodiment of the present invention may be manufactured by press-processing a metal material having excellent heat dissipation, such as aluminum, to form fixing grooves and seating grooves, and then insulating coating them.

In addition, unlike the above, the first and second brackets 30, like the shield plate 24 described above, have insulation, heat resistance, It may be manufactured by injection molding an engineering plastic having excellent rigidity and flame retardancy.

The cooling plate 120 is a component provided to absorb heat from the lower side of the battery cell 10 generated according to charging and discharging through the cooling material (CW) flowing therein, and as described above, the battery unit 110 ) It may be arranged to contact the bottom of the plurality of battery cells 10 constituting the.

In the cooling plate 120 according to an embodiment of the present invention, a cooling passage formed in a zigzag pattern is formed inside to increase the contact time with the cooling material CW, and as shown in FIGS. 1 and 4, the cooling material is cold. An inlet pipe through which (CW) is supplied may be formed on one side, and an outflow pipe through which the cooling material (CW) that absorbs heat from the battery cell 10 is discharged may be formed on the other side.

At this time, the inlet pipe and the outlet pipe may be connected to a cooling cycle device provided in the vehicle through a predetermined pipe while communicating with both ends of the cooling passage formed in a zigzag pattern inside the cooling plate 120 .

Here, the cooling cycle device is a device that cools the cooling material (CW) (cooling water or refrigerant, etc.) and provides it to the cooling plate 120 through a pipe. Although not specifically shown in the drawings, a compressor, a condenser, an expansion valve, and an evaporator It may be a vehicle air conditioning system (HVAC) including the like.

As the cooling material (CW) cooled by the above cooling cycle device is continuously supplied to the inside of the cooling plate 120, that is, to the cooling passage through the pipe, the cooling spacer 130 to be described later is removed from the battery cell 10. The heat transmitted through and through can be continuously cooled from the lower side, and the cooling material (CW), which has been raised in temperature by absorbing heat, can be recovered and cooled by the vehicle cooling cycle device.

The above-described cooling plate 120 includes a plurality of fastening protrusions 122 protruding upward from the upper surface for sliding coupling from the side with the lower frame 136 of the cooling spacer 130 to be described later, aluminum , It may be manufactured through a process in which thermally conductive metals such as copper are press-worked or die-cast, and the upper and lower plates are insulated and bonded to each other.

The cooling spacer 130 mediates so that the heat generated from the battery cell 10 is smoothly transferred to the cooling plate 120 below or the upper cover 140 through the lateral direction, while the battery cell 10 As a component provided to suppress swelling, the lower end may be bonded to the upper surface of the aforementioned cooling plate 120 while being disposed between the battery cells 10 .

The cooling spacer 130 according to an embodiment of the present invention is a central frame 132 as shown in FIGS. 2 and 3 to implement the functions or actions as described above and simplify the assembly process of the battery module 100. ), the upper frame 134 and the lower frame 136 are integrally manufactured by extruding or die-casting a thermally conductive material.

At this time, extrusion molding or die casting is a processing method that has some similar characteristics to injection molding in which a product is molded by injecting a high-temperature molten material into a mold. , Production of the cooling spacer 130 according to the present invention due to the feature of being able to continuously manufacture a product having a complex cross-sectional shape and a hollow (S) along the extrusion direction (ED) at once without welding or a separate bonding process. to be applied specifically.

The central frame 132 is a plate-shaped component interposed between the battery cells 10 so that adjacent battery cells 10 come into surface contact with opposite sides, and one hollow S may be formed therein. there is.

The hollow (S) is filled with a phase change material (PM) that reduces or buffers heat transfer from one side of the battery cell 10 with which the central frame 132 is in surface contact to the other battery cell 10, thereby forming a cooling spacer ( 130) to improve the heat dissipation efficiency.

Here, the phase change material (PM) is a temperature control material that changes state from solid to liquid or from liquid to solid based on a specific temperature range and stores heat (endothermic) or emits heat (heat dissipation), respectively. Alternatively, it may be manufactured to be phase-changed in an intended arbitrary temperature range using various vegetable substances that can be obtained from nature.

The phase change material (PM) prepared as above and filled in the hollow (S) may be an organic paraffinic wax having a phase change temperature range set to 30°C to 35°C.

Due to the phase change material (PM) in this temperature range, the battery cell 10 does not rapidly rise in temperature even if the external temperature exceeds 35 ° C, and the upper limit of the optimum operating temperature of the battery cell 10 is 30 ° C to 35 ° C. Since it can be maintained for a certain period of time, stable operation of the battery module 100 is possible.

On the other hand, as shown in FIG. 4, the above-described one hollow S is formed together during the extrusion molding or die casting process of the cooling spacer 130 by one or more partition walls reinforcing the rigidity of the central frame 132. It can be divided into multiple pieces.

At this time, the cooling material (CW) supplied through one side and discharged through the other side and the above-described phase change material (PM) may be alternately filled in different positions in the hollow (S) divided into a plurality of pieces.

Here, the cooling material (CW) supplied to one side of the hollow (S) is the same as the cooling material (CW) supplied to the inside of the cooling plate 120 through the cooling cycle device as described above, and the central frame 132 It can be supplied and recovered through a predetermined manifold type pipe that is hermetically coupled to the hollow (S) at one end and the other end, respectively, and a cooling cycle device communicating therewith.

As described above, since two different types of thermal management materials are provided in each of the plurality of divided hollows (S), thermal management of the battery cell 10 can be performed more efficiently in a complementary manner, and the Higher thermal stability can be secured.

The upper frame 134 is a plate-shaped component provided to support the upper surface of the battery cell 10 and to transfer the heat generated in the battery cell 10 upward, and the upper end of the central frame 132 is adjacent to the battery. It may be formed by extending left and right during extrusion molding so as to make surface contact with a portion of the upper surface of the cell 10, respectively.

As shown in FIGS. 2 and 3, the upper frame 134 according to an embodiment of the present invention is spaced apart from each other on the upper surface of the upper frame 134 and protrudes upward for a long time along the extrusion direction ED. It is made of a structure including a heat dissipation fin (134a).

Due to the structure of the heat dissipation fins 134a of the upper frame 134, the heat of the battery cells 10 transferred to the central frame 132 is more smoothly and quickly dissipated upward, so that the thermal management of the battery cells 10 is improved. can be done more easily.

The lower frame 136 is a plate-shaped component provided to support the lower surface of the battery cell 10 and transfer heat generated from the battery cell 10 to the cooling plate 120 below, and the central frame 132 The lower end of may be formed by extending to the left and right during extrusion molding so as to make surface contact with a portion of the lower surface of the battery cell 10 adjacent to each other.

As shown in FIGS. 1 to 3, the lower frame 136 according to an embodiment of the present invention has a groove shape corresponding to the above-described fastening protrusion 122 and is formed with a long depression along the extrusion direction ED on the lower surface. It is made of a structure including a fastening groove 138.

Due to the fastening groove 138 and the above-described fastening protrusion 122, the cooling plate 120 and the cooling spacer 130 can be easily slide-coupled from the side without using a separate working tool.

In addition, as the cooling plate 120 and the cooling spacer 130 are in close contact with each other without lifting or gap and form a strong bonding force, a gap filler (TIM, Thermal Interface) filled between the battery cell 10 and the cooling plate 120 Material), it is possible to achieve smooth heat transfer between them.

As shown in FIG. 1, the upper cover 140 forms an internal space together with the side cover 20, the first and second brackets 30, and the cooling plate 120 to protect it from external impact or the external environment. As a plate-shaped component that accommodates and protects the battery unit 110 described above, it is disposed to cover the upper surface of the battery unit 110 to form the upper surface of the battery module 100 .

The upper cover 140 according to the embodiment of the present invention, as shown in FIG. 4 to quickly cool the heat dissipation fins 134a of the upper frame 134, the internal passage through which the cooling material CW flows therein ( 142) may be formed, and the heat dissipation fin 134a may be penetrated and coupled to the internal passage 142.

At this time, the internal passage 142 may be formed in a zigzag shape to increase the contact time with the cooling material CW, similar to the cooling passage of the cooling plate 120 described above, and shown in FIGS. 1 and 4 As shown, an inlet pipe through which the cold cooling material CW is supplied may be formed on one side, and an outflow pipe through which the cooling material CW that has absorbed heat from the heat dissipation fin 134a is discharged may be formed on the other side.

At this time, the inlet pipe and the outlet pipe may also be connected to the above-mentioned cooling cycle device provided in the vehicle through a predetermined pipe while communicating with both ends of the internal passage 142 .

As the cooling material (CW) cooled by the cooling cycle device as described above is continuously provided to the internal flow path 142 of the upper cover 140 through the pipe, from the battery cell 10 through the cooling spacer 130, the heat dissipation fin The heat transferred to (134a) can be continuously cooled from the upper side, and the cooling material (CW), which is heated by endothermic heat, can be recovered and cooled by the vehicle cooling cycle device.

The above-described upper cover 140 may be manufactured through a process of bonding an upper plate and a lower plate obtained by press-working or die-casting a heat-conductive metal such as aluminum or copper with insulating coating and then bonding them to each other.

As described above, according to the battery module 100 having enhanced cooling performance according to an embodiment of the present invention, the heat generated in the battery unit 110 is stored between the battery cells 10, and the battery Through the cooling spacer 130 thermally and physically closely coupled to the cooling plate 120 at the bottom of the unit 110, the cooling plate 120 on the lower side as well as the upper cover 140 on the upper side are transferred and dissipated, Thermal management of the battery cell 10 can be achieved three-dimensionally and efficiently, and a higher level of thermal stability of the battery cell 10 can be secured.

In the foregoing, although specific embodiments of the present invention have been described and shown, the present invention is not limited to the described embodiments, and it is common knowledge in the art that various modifications and variations can be made without departing from the spirit and scope of the present invention. It is self-evident to those who have Therefore, such modifications or variations should not be individually understood from the technical spirit or viewpoint of the present invention, and modified embodiments should fall within the scope of the claims of the present invention.

10: battery cell
12: lead tab
20: side cover
22: end plate
24: shielding plate
30: first bracket, second bracket
32: bus bar
100: battery module with enhanced cooling performance
110: battery unit
120: cooling plate
CW: coolant
122: fastening protrusion
130: cooling spacer
132: central frame
S: hollow
PM: phase change material
ED: extrusion direction
134: upper frame
134a: radiation fin
136: lower frame
138: fastening groove
140: upper cover
142: internal flow path

Claims (7)

A battery module that houses and protects a battery unit formed by stacking a plurality of battery cells in the horizontal direction,
a cooling plate provided below the battery unit and absorbing heat generated from the battery cell through a cooling material supplied from the outside and flowing inside; And a cooling spacer disposed between the battery cells and bonded to the cooling plate to mediate heat transfer to the cooling plate and extruded from a thermally conductive material to suppress swelling of the battery cell,
The cooling spacer,
a central frame interposed between the battery cells so that adjacent side surfaces of the battery cells facing each other are in surface contact with each other, and a hollow is formed therein; an upper frame extending from an upper end of the central frame to make surface contact with portions of the upper surface of the battery cells adjacent to each other; And a lower frame extended from a lower end of the central frame and bonded to the cooling plate so as to make surface contact with portions of the lower surfaces of the battery cells adjacent to each other,
In the hollow,
A battery module having enhanced cooling performance, characterized in that a phase change material is filled in order to reduce heat transfer between adjacent battery cells and improve heat dissipation efficiency. A battery module that houses and protects a battery unit formed by stacking a plurality of battery cells in the horizontal direction,
a cooling plate provided below the battery unit and absorbing heat generated from the battery cell through a cooling material supplied from the outside and flowing inside; And a cooling spacer disposed between the battery cells and bonded to the cooling plate to mediate heat transfer to the cooling plate and extruded from a thermally conductive material to suppress swelling of the battery cell,
The cooling spacer,
a central frame interposed between the battery cells so that adjacent side surfaces of the battery cells facing each other are in surface contact with each other, and a hollow is formed therein; an upper frame extending from an upper end of the central frame to make surface contact with portions of the upper surface of the battery cells adjacent to each other; And a lower frame extended from a lower end of the central frame and bonded to the cooling plate so as to make surface contact with portions of the lower surfaces of the battery cells adjacent to each other,
the hollow,
It is divided into a plurality of pieces by one or more partition walls reinforcing the rigidity of the central frame,
In the hollow divided into a plurality of pieces,
A battery module having enhanced cooling performance, characterized in that the cooling material and the phase change material supplied through one side and discharged through the other side are alternately filled in different positions. According to claim 1 or 2,
The upper frame,
Reinforced cooling characterized in that it comprises a plurality of heat dissipation fins spaced apart from each other on the upper surface of the upper frame and protruding upward along the extrusion direction in order to dissipate the heat of the battery cells transmitted to the central frame upward. Battery module with performance. According to claim 1 or 2,
The lower frame,
In order to slide and engage the lower frame laterally with respect to the plurality of fastening protrusions protruding upward from the upper surface of the cooling plate, the lower surface of the lower frame is formed in a groove shape corresponding to the fastening protrusions and is formed long along the extrusion direction. Battery module having enhanced cooling performance, characterized in that it comprises a fastening groove. delete delete According to claim 3,
The battery module,
The battery module having enhanced cooling performance, characterized in that it further comprises an upper cover disposed to cover an upper surface of the battery unit and through-coupled to the heat dissipation fin so that the heat dissipation fin is cooled by a cooling material flowing through an internal passage.

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