CN110010995A - A battery pack thermal management system based on a flat heat pipe and its working method - Google Patents

Abstract

The invention relates to the field of power battery thermal management, and discloses a battery pack thermal management system based on a flat heat pipe, comprising a battery pack, a flat heat pipe, a U-shaped graphite sheet and a heat exchange plate; the battery pack comprises a plurality of square single The U-shaped graphite sheet is in one-to-one correspondence with the single battery; the U-shaped graphite sheet covers at least two opposite sides of the single battery to form a battery unit, and multiple battery units are sequentially attached to form a battery unit. A battery module; a plurality of the heat exchange plates are arranged at intervals in sequence, the battery module is arranged in the interval between two adjacent heat exchange plates along its length direction, and the flat heat pipe is located between the battery module and the heat exchange plates. The invention also discloses a working method of a battery pack thermal management system based on a flat heat pipe. It can effectively improve the uniformity of the internal temperature of the battery pack.

Description

A battery pack thermal management system based on a flat heat pipe and its working method

technical field

The invention relates to the field of power battery thermal management, in particular to a battery pack thermal management system based on a flat plate heat pipe and a working method thereof.

Background technique

As the main power source of electric vehicles, the parameters and performance of batteries directly affect the power, safety and economy of electric vehicles. During the operation of the battery, heat will be generated, which will increase the battery temperature, resulting in changes in the battery voltage and thermal runaway; in the cold winter areas, the battery temperature is too low, the battery capacity, power and charging and discharging efficiency will decrease, making the cruising range and The maximum speed is greatly reduced. The uneven temperature of the battery pack will lead to uneven discharge of the battery pack, and the local temperature difference of the single cell may even lead to the phenomenon of pressure difference and mechanism expansion. Therefore, research on efficient battery thermal management technology is particularly important to improve the performance of electric vehicles.

The heat pipe or cold water pipe is in contact with the battery as a common heat dissipation method for battery thermal management to absorb the heat generated by the battery, which makes the heat exchange area extremely limited, the heat exchange is concentrated, and the temperature distribution inside the single battery is uneven. When heating the battery, the phenomenon of increasing the temperature difference due to the heating concentration also occurs.

SUMMARY OF THE INVENTION

The purpose of the present invention is to overcome the above shortcomings of the prior art, and to provide a battery pack thermal management system based on a flat heat pipe, which aims to efficiently dissipate/heat the single cells while ensuring the uniformity of the battery pack temperature. . Another object of the present invention is to provide a working method of a battery pack thermal management system based on a flat heat pipe.

The object of the present invention is achieved through the following technical solutions: a battery pack thermal management system based on a flat heat pipe, comprising a battery pack, a flat heat pipe, a U-shaped graphite sheet and a heat exchange plate with a circulating fluid inside; the battery pack It includes a plurality of square single cells, the U-shaped graphite sheets correspond to the single cells one-to-one, and the U-shaped graphite sheets cover at least two opposite sides of the single cells to form a battery unit, and a plurality of The battery cells are laminated in sequence to form a battery module; wherein, the two side plates of each U-shaped graphite sheet are parallel to the length direction of the battery module, a plurality of the heat exchange plates are arranged at intervals in sequence, and the battery module is along its length direction. It is arranged in the interval between two adjacent heat exchange plates, the flat heat pipe is located between the battery module and the heat exchange plate, one side of the flat heat pipe is closely attached to the U-shaped graphite sheet, and the other side is closely attached to the heat exchange plate fit.

Further, the size of the two side plates of the U-shaped graphite sheet is matched with the two opposite sides of the single cell, so that the two side plates of the U-shaped graphite sheet completely cover the two opposite sides of the single cell. , the two side plates of the U-shaped graphite sheet are parallel to the length direction of the battery module.

Further, the U-shaped graphite sheet completely covers three adjacent sides of the single battery, two of which are arranged opposite to each other, and the two sides are parallel to the length direction of the battery module, and the other side is perpendicular to the battery module. In the length direction of the U-shaped graphite sheet, the U-shaped graphite sheet has opposite open ends and closed ends. In the same battery module, the open end of the U-shaped graphite sheet is attached to the back of the closed end of the adjacent U-shaped graphite sheet, so that the monomer The four sides of the battery are attached to the U-shaped graphite sheet.

Further, the heat exchange plate has a plurality of circulating flow channels inside, and each of the circulating flow channels has a working medium inlet and a working medium outlet arranged oppositely.

Further, the circulating flow channel includes at least two parallel flow channels, each parallel flow channel is connected in parallel, one end of each parallel flow channel is connected to the working medium inlet, and the other end of each parallel flow channel is connected to the working medium inlet. Connect with the working fluid outlet.

Further, the flat plate heat pipe is a sintered liquid-absorbing wick type steam cavity flat plate heat pipe with a support column inside.

Further, the battery module has a rectangular parallelepiped structure.

Further, thermally conductive silica gel is coated between the flat heat pipe and the U-shaped graphite sheet and between the flat heat pipe and the heat exchange plate.

A working method of a battery pack thermal management system based on a flat heat pipe, comprising the following steps:

Heat dissipation process: When the working temperature of the battery pack is too high, the working fluid circulating in the heat exchange plate is the cooling working fluid, and the heat generated by the single battery is transferred to the heat exchange plate through the U-shaped graphite sheet and the flat heat pipe in turn; at the same time, The cooling medium flows in from the inlet of the working medium, and flows out from the outlet of the working medium after absorbing heat to achieve cooling of the battery pack; during the heat dissipation process, the side of the flat heat pipe in contact with the U-shaped graphite sheet is the heat absorption surface, and the flat heat pipe and the heat exchange The side in contact with the plate is the exothermic surface;

Heating process: When the battery pack works in a low temperature environment, the working fluid circulating in the heat exchange plate is the heating working fluid, and the heating working fluid acts as a heat source, which flows in from the working fluid inlet, and then flows out from the working fluid outlet after releasing heat; at the same time, the heat It passes through the heat exchange plate, the flat heat pipe and the U-shaped graphite sheet in turn, and is transferred to the battery pack to realize the heating of the battery pack; in the heating project, the side of the flat heat pipe in contact with the heat exchange plate is the heat absorption surface, and the flat heat pipe and the U-shaped The contact side of the graphite sheet is the exothermic surface.

Further, the cooling working medium is water or an aqueous ethylene glycol solution, and the heating working medium is water or an aqueous ethylene glycol solution.

Compared with the prior art, the present invention has the following advantages:

1. The battery pack thermal management system of the present invention has a simple and compact structure, small footprint, convenient and flexible arrangement, high safety, and low manufacturing cost. The combination of graphite sheet, flat heat pipe and heat exchange plate, on the basis of graphite sheet, combined with the characteristics of large heat exchange area and strong heat transfer performance of flat heat pipe, makes the temperature distribution of the battery pack uniform, and the single cells are not in direct contact The heat exchange plate can effectively avoid the danger of liquid leakage and greatly improve the safety of the battery thermal management system.

2. The surrounding of the single battery in the present invention is covered by graphite sheets. Graphite has good plasticity and toughness, is light and thin, and has strong thermal conductivity. Graphite is used as a thermal conductive material, which is conducive to the uniform conduction of heat and effectively improves the temperature of the battery pack. uniformity.

3. The plate heat pipe in the present invention is a sintered liquid-absorbing core type steam cavity plate heat pipe with a support column inside; compared with the ordinary heat pipe, the plate-shaped structure of the heat pipe can have better contact with the graphite sheet and the heat exchange plate; The support column made of sintered powder in the heat pipe can effectively improve the rigidity and critical heat flux density of the flat plate heat pipe. Thermal efficiency: The working fluid inside the flat heat pipe transfers heat evenly in the form of phase change in the steam cavity, so that the surface temperature of the flat heat pipe is uniform, which is beneficial to improve the temperature uniformity of the battery pack.

4. The arrangement of the parallel flow channels in the heat exchange plate of the present invention is simple, the resistance of the flowing working medium in the flow process is small, and the energy loss is small, which is beneficial to reduce the secondary energy consumption in the thermal management system. The materials used in the invention are energy-saving and environmentally friendly, easy to install and easy to maintain, can meet the heat exchange requirements of the square battery pack under different working conditions, ensure that the battery works within a suitable temperature range, and have broad application prospects.

Description of drawings

FIG. 1 shows a schematic structural diagram of a battery pack thermal management system based on a flat heat pipe according to the present invention;

Fig. 2 shows the top view of Fig. 1;

Fig. 3 shows the exploded view at A in Fig. 2;

FIG. 4 shows a schematic structural diagram of the U-shaped graphite sheet and the single cell being bonded according to the present invention;

Fig. 5 shows the structural schematic diagram of the heat exchange plate according to the present invention;

Fig. 6 shows the flow schematic diagram of the working medium flowing in the circulating flow channel according to the present invention;

In the figure, 1 is a U-shaped graphite sheet; 101 is an open end; 102 is a closed end; 2 is a battery pack; 201 is a single battery; 3 is a flat heat pipe; 4 is a heat exchange plate; Working medium inlet; 403 is working medium outlet; 404 is parallel flow channel.

Detailed ways

The present invention will be further described below with reference to the accompanying drawings and embodiments.

Example:

As shown in FIG. 1-FIG. 3, a battery pack thermal management system based on a flat heat pipe includes a battery pack 2, a flat heat pipe 3, a U-shaped graphite sheet 1 and a heat exchange plate 4 with a circulating fluid inside; the The battery pack 2 includes a plurality of square single cells 201 , the U-shaped graphite sheets 1 are in one-to-one correspondence with the single cells 201 , and the U-shaped graphite sheets 1 at least cover two opposite sides of the single cells 201 . In order to form a battery unit, a plurality of battery units are laminated in sequence to form a battery module, wherein the two side plates of the U-shaped graphite sheet 1 are parallel to the length direction of the battery module, (ie: the two sides of the multiple U-shaped graphite sheets 1 . The side plates are arranged in sequence along the length direction of the battery module) A plurality of the heat exchange plates 4 are arranged at intervals in sequence, the battery modules are arranged in the interval between two adjacent heat exchange plates 4 along the length direction, and the flat heat pipes 3 are located in the battery Between the module and the heat exchange plate 4 , one side of the flat heat pipe 3 is closely attached to the U-shaped graphite sheet 1 , and the other side is closely attached to the heat exchange plate 4 . The U-shaped graphite sheets 1 on both sides of the single cell 201 are attached to the flat heat pipe 3, and the U-shaped graphite sheet 1 is in indirect contact with the heat exchange plate 4 through the flat heat pipe 3. This structure can effectively avoid the flow passage in the heat exchange plate 4. safety issues caused by leakage. Adjacent battery modules use the same heat exchange plate 4 for heat exchange, so that the system has a simple and compact structure and a small footprint. When the temperature of the battery pack 2 is high, the heat generated by the single cell 201 is transferred to the flat heat pipe 3 through the U-shaped graphite sheet 1, and then the cooling medium flowing in the heat exchange plate 4 takes the heat away, so as to realize the heat transfer to the battery pack 2. When the working environment temperature of the battery pack 2 is low, the heating working fluid flows in the heat exchange plate 4, and the heat of the heating working fluid is transferred to the single cell 201 through the flat heat pipe 3 and the U-shaped graphite sheet 1, so as to realize the heating and cooling of the battery. Group 2 heating. This design arrangement is convenient and flexible, and has high safety, and can ensure that the single battery 201 works within a suitable temperature range.

The size of the two side plates of the U-shaped graphite sheet 1 is matched with the two opposite sides of the single cell 201, so that the two side plates of the U-shaped graphite sheet 1 completely cover the two opposite sides of the single cell 201. On the side, both side plates of the U-shaped graphite sheet are parallel to the length direction of the battery module. By adopting this structure, the heat exchange efficiency between the U-shaped graphite sheet 1 and the single cell 201 can be improved, and the temperature uniformity of the single cell 201 itself can be improved.

As shown in FIG. 3 and FIG. 4 , the volume of the U-shaped graphite sheet 1 is equal to the volume of the single cell 201, so that the U-shaped graphite sheet 1 completely covers the three adjacent sides of the single cell 201, Two of the side surfaces are arranged opposite to each other, and the two side surfaces are parallel to the length direction of the battery module, and the other side surface is perpendicular to the length direction of the battery module. The U-shaped graphite sheet 1 has an opposite open end 101 and a closed end 102. The same In the battery module, the open end 101 of the U-shaped graphite sheet 1 is attached to the back of the closed end 102 of the adjacent U-shaped graphite sheet 1, so that the four sides of the single cell 201 are attached to the U-shaped graphite sheet 1. . With this structure, the four sides of the single cell 201 are surrounded by the U-shaped graphite sheet 1 , and the adjacent single cells 201 do not contact each other, which is beneficial to reduce the mutual influence between the adjacent single cells 201 . At the same time, the U-shaped graphite sheet 1 has good thermal conductivity, which is beneficial to reduce the temperature difference between the single cells 201 and maintain the temperature uniformity of the battery pack 2 .

As shown in FIG. 5 , the heat exchange plate 4 has a plurality of circulating flow channels 401 inside, and each of the circulating flow channels 401 has a working medium inlet 402 and a working medium outlet 403 arranged oppositely. The arrangement of multiple circulating flow channels 401 can improve the uniformity of the distribution of the flowing working medium in the heat exchange plate 4, thereby improving the heat exchange efficiency of the entire system.

As shown in FIG. 5 and FIG. 6 , the circulating flow channel 401 includes three parallel flow channels 404, and each parallel flow channel 404 is connected in parallel. One end of each of the parallel flow channels 404 is connected to the working medium inlet 402. The other ends of the parallel flow channels 404 are all connected to the working medium outlet 403 . The parallel flow channels 404 are arranged in parallel, and the parallel flow channels 404 are all rectangular, with reasonable design and simple structure, so that the resistance of the flowing working medium is small during the flow process, and the energy loss is small, which is beneficial to reduce the thermal management system. Secondary energy consumption.

The flat plate heat pipe 3 is a sintered liquid-absorbing wick type steam cavity flat plate heat pipe with a support column inside. The plate heat pipe 3 with the steam cavity not only has a strong heat transfer ability in the normal direction of the plate, but also helps to uniformly transfer the heat generated by the heat source on the entire plate, which can effectively eliminate hot spots and improve the heat exchange effect; the plate heat pipe The flat-plate structure of 3 is also easy to contact with the U-shaped graphite sheet 1 and the heat exchange plate 4, which simplifies the installation of the system. Such flat heat pipes 3 can be purchased from the market.

The battery module has a rectangular parallelepiped structure. The battery module of the rectangular parallelepiped structure is matched with the flat plate structure of the flat plate heat pipe 3, and the whole system has a compact structure, which effectively improves the heat exchange efficiency.

Thermally conductive silica gel is coated between the flat heat pipe 3 and the U-shaped graphite sheet 1 and between the flat heat pipe 3 and the heat exchange plate 4 . This setting can reduce thermal resistance and improve the heat exchange efficiency of the system.

A working method of a battery pack thermal management system based on a flat heat pipe, comprising the following steps:

Heat dissipation process: When the working temperature of the battery pack 2 is too high, the working fluid circulating in the heat exchange plate 4 is the cooling working fluid, and the heat generated by the single battery 201 is sequentially transferred to the heat exchange through the U-shaped graphite sheet 1 and the flat heat pipe 3. At the same time, the cooling working medium flows in from the working medium inlet 402 and flows out from the working medium outlet 403 after absorbing heat to realize the cooling of the battery pack 2; during the heat dissipation process, the flat heat pipe 3 is in contact with the U-shaped graphite sheet 1. One side is the heat absorption surface, and the side of the flat heat pipe 3 in contact with the heat exchange plate 4 is the heat release surface;

Heating process: When the battery pack 2 is working in a low temperature environment, the working fluid circulating in the heat exchange plate 4 is the heating working fluid, and the heating working fluid is used as a heat source, which flows in from the working fluid inlet 402 and flows out from the working fluid outlet 403 after releasing heat. At the same time, the heat passes through the heat exchange plate 4, the flat heat pipe 3 and the U-shaped graphite sheet 1 in turn, and is transferred to the battery pack 2 to realize the heating of the battery pack 2; The side is the heat absorption surface, and the side of the flat heat pipe 3 in contact with the U-shaped graphite sheet 1 is the heat release surface.

The cooling working medium is water or an aqueous ethylene glycol solution, and the heating working medium is water or an aqueous ethylene glycol solution. In specific use, the cooling working fluid is at room temperature, and the heating working fluid can be used after heating.

The above-mentioned specific embodiments are the preferred embodiments of the present invention, and do not limit the present invention. Any other changes or other equivalent replacement methods that do not deviate from the technical solutions of the present invention are included in the protection scope of the present invention. within.

Claims (10)

1. a kind of battery pack thermal management system based on flat-plate heat pipe, it is characterised in that: including battery pack, flat-plate heat pipe, U-shaped stone Ink sheet and inside have the heat exchanger plates for circulating working medium；The battery pack includes multiple single batteries being square, described U-shaped Graphite flake and single battery correspond, and the U-shaped graphite flake coats two opposite sides of single battery at least to form One battery unit, multiple battery units are successively bonded to form a battery module；Multiple described heat exchanger plates, which are successively spaced, to be set It sets, the battery module is set to along its length in the interval of two adjacent heat exchanger plates, and the flat-plate heat pipe is located at battery Between module and heat exchanger plates, the one side of the flat-plate heat pipe is fitted closely with U-shaped graphite flake, and another side is tight with heat exchanger plates Closely connected conjunction.

2. the battery pack thermal management system according to claim 1 based on flat-plate heat pipe, it is characterised in that: the U-shaped stone The size of the both side plate of ink sheet and two opposite sides of single battery match, so that the both side plate of U-shaped graphite flake is complete Coat two opposite sides of single battery, the length direction of the both side plate of the U-shaped graphite flake each parallel to battery module.

3. the battery pack thermal management system according to claim 1 based on flat-plate heat pipe, it is characterised in that: the U-shaped stone Ink sheet coats three adjacent sides of single battery completely, and two of them side is oppositely arranged, and this two sides are parallel to The length direction of battery module, perpendicular to the length direction of battery module, the U-shaped graphite flake has opposite for another side Open end and closed end, in same battery module, the closed end of the open end of U-shaped graphite flake U-shaped graphite flake adjacent thereto Back fitting so that four sides of single battery are bonded with U-shaped graphite flake.

4. the battery pack thermal management system according to claim 1 based on flat-plate heat pipe, it is characterised in that: the heat exchanger plates Inside has multiple circulatory flows, and each circulatory flow all has the working medium import being oppositely arranged and sender property outlet.

5. the battery pack thermal management system according to claim 4 based on flat-plate heat pipe, it is characterised in that: the recycle stream Road includes at least two parallel fluid channels, is connected in parallel between each parallel fluid channels, and one end of each parallel fluid channels is and work Matter import connection, the other end of each parallel fluid channels are connect with sender property outlet.

6. the battery pack thermal management system according to claim 1 based on flat-plate heat pipe, it is characterised in that: the plate heat Pipe is the internal sintered wicks formula vapor chamber flat-plate heat pipe with support column.

7. the battery pack thermal management system according to claim 1 based on flat-plate heat pipe, it is characterised in that: the battery mould Block is in rectangular parallelepiped structure.

8. the battery pack thermal management system according to claim 1 based on flat-plate heat pipe, it is characterised in that: the plate heat Heat conductive silica gel is coated between the flat-plate heat pipe and heat exchanger plates between pipe and U-shaped graphite flake.

9. a kind of work side of the battery pack thermal management system according to claim 1 to 8 based on flat-plate heat pipe Method, which is characterized in that include the following steps,

Radiation processes: when the operating temperature of battery pack is excessively high, the working medium of heat exchanger plates internal circulation flow is cooling working medium, monomer electricity The heat that pond generates successively is transferred to heat exchanger plates by U-shaped graphite flake and flat-plate heat pipe；Meanwhile working medium is cooled down from working medium inlet flow Enter, is flowed out after absorbing heat from sender property outlet, realize the cooling to battery pack；In radiation processes, flat-plate heat pipe and U-shaped graphite flake The side of contact is heat-absorbent surface, and the side that flat-plate heat pipe is contacted with heat exchanger plates is heat delivery surface；

Heating process: when battery pack is when low temperature environment works, the working medium of heat exchanger plates internal circulation flow is heating working medium, heater Matter is flowed into as heat source from working medium import, is flowed out after releasing heat from sender property outlet；Meanwhile heat successively passes through heat exchanger plates, puts down Plate heat pipe and U-shaped graphite flake are transferred to battery pack, realize the heating to battery pack；It heats in engineering, flat-plate heat pipe and heat exchanger plates The side of contact is heat-absorbent surface, and the side that flat-plate heat pipe is contacted with U-shaped graphite flake is heat delivery surface.

10. the working method of the battery pack thermal management system according to claim 9 based on flat-plate heat pipe, feature exist In: the cooling working medium is water or glycol water, and the heating working medium is water or glycol water.