Electric vehicle battery chassis assembly, electric vehicle and use method

Abstract

The invention provides an electric vehicle battery chassis assembly which comprises a battery pack (1), a buffer cavity (2), a one-way exhaust valve (3), a communicating pipe (4), a communicating valve (5), a liquid cooling plate (6), a buffer partition plate (7), a through hole (8), a heat pipe (9) and a device for providing external fluid, and the device comprises a main pipe (10), a first branch pipe (11), a second branch pipe (12), a delivery pump (13), a vacuum pump (14), a first valve (15), a second valve (16), a liquid storage chamber (17), a heat exchanger (18) and a refrigerating and heating unit (19). According to the scheme, by means of the buffer cavity (2) existing in terms of the total cost of the battery chassis of the electric vehicle, only the one-way exhaust valve (3) and the communicating pipe (4) with the communicating valve (5) at the tail end need to be additionally arranged on the original buffer cavity (2), transformation is easy, and the influence on an original vehicle body is small; high-speed heat exchange between externally injected fluid and original cooling liquid of the liquid cooling plate (6) is achieved through the heat pipe (9), the externally injected fluid is pumped away after heat exchange is finished, and original mass distribution of the electric automobile is not affected while liquid recycling is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of electric vehicle thermal management, and in particular to an electric vehicle battery chassis assembly, an electric vehicle and a use method thereof. Background Art

[0002] At present, electric vehicles are mainly powered by lithium-ion battery packs located on their chassis. The charging and discharging of lithium-ion battery packs need to be carried out in a suitable temperature environment. Although electric vehicles have certain thermal management functions during operation, when electric vehicles are charged or parked under high or low ambient temperatures, their own thermal management functions have great limitations due to factors such as limited cooling and heating capabilities, time consumption and power consumption. Therefore, it is necessary to develop additional electric vehicle battery thermal management auxiliary technologies to overcome the limitations of electric vehicles' own thermal management functions under harsh climatic conditions such as low or high ambient temperatures. Summary of the invention

[0003] The main purpose of the present invention is to provide an electric vehicle battery chassis assembly, an electric vehicle and a method of use, aiming to solve the technical problem that the electric vehicle's own thermal management function is limited when the external ambient temperature is high or low, thereby providing auxiliary thermal management for the electric vehicle's charging process and starting requirements after parking.

[0004] To achieve the above object, the present invention provides an electric vehicle battery chassis assembly, comprising a battery pack and buffer chambers arranged on both sides of the battery pack, wherein:

[0005] The buffer chamber is used to provide buffer protection for the battery pack when the electric vehicle is subjected to external impact, and a one-way exhaust valve and a connecting pipe are provided on the wall surface of the buffer chamber;

[0006] A connecting valve is provided at the end of the connecting pipe. When the connecting valve is opened, the external fluid medium can be injected into the buffer cavity through the connecting valve and the connecting pipe in sequence.

[0007] Optionally, the above-mentioned electric vehicle battery chassis assembly also includes a liquid cooling plate for exchanging heat with the battery pack, and the liquid cooling plate is filled with coolant.

[0008] Optionally, in the above-mentioned electric vehicle battery chassis assembly, a buffer partition is also provided in the buffer cavity to provide support to increase the impact resistance of the buffer cavity.

[0009] Optionally, in the above-mentioned electric vehicle battery chassis assembly, the buffer partition is provided with a through hole to facilitate the free flow of the fluid medium injected into the buffer cavity without being blocked by the buffer partition.

[0010] Optionally, the above-mentioned electric vehicle battery chassis assembly further includes a heat pipe, one end of which is located in the buffer cavity, and the other end of which is connected to the liquid cooling plate.

[0011] Specifically, in order to provide support and accommodation for the various components of the above-mentioned electric vehicle battery chassis assembly, the electric vehicle battery chassis assembly also includes a chassis body.

[0012] The present invention also provides an electric vehicle, which is provided with the electric vehicle battery chassis assembly described in any one of the above items.

[0013] The present invention also provides a method for using the electric vehicle battery chassis assembly as described in any of the above items. When the electric vehicle is in a parking state and its own thermal management capability cannot meet the cooling or heating requirements of its battery pack, the connecting valve is opened, and the external cold fluid or hot fluid is injected into the buffer cavity through the connecting valve and the connecting pipe in sequence; this is maintained for a certain period of time, and when the electric vehicle no longer needs the heat exchange provided by the external fluid, the buffer cavity is evacuated through the connecting pipe to suck out the external cold fluid or hot fluid, and finally the connecting valve is closed.

[0014] Optionally, in the method for using the electric vehicle battery chassis assembly, the cold fluid or hot fluid is water.

[0015] Optionally, in the method of using the electric vehicle battery chassis assembly, the temperature of the cold fluid when injected is between 5°C and 25°C, and the temperature of the hot fluid when injected is between 35°C and 55°C.

[0016] Optionally, in the method of using the battery chassis assembly of an electric vehicle, when the buffer cavity is filled with an external cold fluid or hot fluid, the coolant in the liquid cooling plate is in a circulating flow state.

[0017] It should be pointed out that the buffer chamber is a closed structure, so as to facilitate vacuuming to suck out the external fluid. In the process of injecting the external fluid into the buffer chamber through the connecting valve and the connecting pipe, the pressure in the buffer chamber increases, and the gas originally existing in the buffer chamber is discharged through the one-way exhaust valve under the action of pressure to facilitate the injection of the external fluid; when the buffer chamber is vacuumed through the connecting pipe, the external gas cannot enter through the one-way exhaust valve, so the liquid retained in the buffer chamber can be sucked out.

[0018] The beneficial effects of the technical solution of the present invention are introduced below in combination with the principle thereof.

[0019] First, imagine two major usage scenarios for electric vehicles.

[0020] Scenario 1: After driving in a high temperature environment for a period of time, the electric car is running low on power and is parked outdoors for charging. At the beginning of charging, the temperature of the battery pack is very high and needs to be lowered to a suitable temperature before normal charging can be performed. At this time, if the electric car's own cooling function is used to cool the battery pack, its cooling power is limited; secondly, the electric car itself has very little power left and cannot bear the power required for cooling. The charging process is fast charging, and the battery pack generates a lot of heat. At this time, if the electric car's own cooling function is used to cool the battery pack, its cooling power is limited; secondly, it will inevitably reduce the charging current that the battery pack can share, reducing its own charging rate.

[0021] Scenario 2: After an electric car has been parked for a long time in a cold outdoor environment, the owner needs to drive away. Since the battery pack is in a low temperature state, it cannot provide enough discharge power for the electric car in a short time to meet its driving needs.

[0022] Therefore, it is necessary to provide thermal management auxiliary services with external functions for electric vehicles in the parking state in parking spaces to meet the needs of fast charging of vehicles in severe weather conditions such as excessively high or low ambient temperatures and fast starting after long-term parking.

[0023] The battery chassis assembly of current electric vehicles carries the battery pack and is usually provided with a buffer cavity on both sides to provide protection for the battery pack: when the electric vehicle is hit by an external impact, the buffer cavity deforms and absorbs the impact energy, thereby greatly reducing damage to the battery pack and reducing the risk of fire and explosion of the battery pack. The buffer cavity is mostly a hollow structure, and under normal circumstances, the buffer cavity hardly plays any role and is completely a "dead volume" on the electric vehicle.

[0024] The auxiliary thermal management technical means of the present invention makes full use of the buffer cavity on the existing battery chassis assembly. The technical means is to add a one-way exhaust valve and a connecting pipe with a connecting valve at the end to the existing buffer cavity. When the vehicle is in a parking state and its own thermal management capacity cannot meet the cooling or heating requirements of its battery pack, the auxiliary thermal management means can be used: open the connecting valve, and inject the external cold fluid or hot fluid into the buffer cavity through the connecting valve and the connecting pipe in turn. The fluid medium generally uses liquid. In order to facilitate the injection of liquid, the buffer cavity is provided with a one-way exhaust valve to naturally exhaust to the external environment when the liquid is injected, thereby providing an internal space for the newly injected liquid. After the liquid is filled, one end of the heat pipe in the buffer cavity is immersed, and the other end of the heat pipe is connected to the liquid cooling plate, thereby providing a high-speed heat transfer channel between the fluid in the buffer cavity and the coolant in the liquid cooling plate by relying on the heat pipe, relying on the cold fluid or hot fluid in the buffer cavity whose temperature has been adjusted in advance, to provide a strong cooling and heating effect for the coolant in the liquid cooling plate, and further provide cooling and heating for the battery pack in contact with the liquid cooling plate. In order to further improve the heat exchange effect and make the temperature of the battery pack evenly distributed as much as possible, when the buffer cavity is filled with external cold fluid or hot fluid, the circulation pump connected to the flow channel in the liquid cooling plate is started to circulate the coolant in the liquid cooling plate. Although the circulation pump has a certain power consumption, its power is usually only tens of watts to hundreds of watts, which is much lower than the air conditioners and PTC heating elements used for cooling and heating in the electric vehicle thermal management system, which are often several kilowatts or even higher.

[0025] A heat pipe is a highly efficient heat transfer element that makes full use of the principle of heat conduction and the rapid heat transfer properties of phase change media. It quickly transfers the heat of a heating object to the outside of the heat source through the heat pipe, and its thermal conductivity exceeds that of any known metal. A heat pipe has two ends, usually on the heat source side and the cold source side respectively. It uses the phase change process of the internal medium evaporating at the hot end and condensing at the cold end (i.e., using the latent heat of evaporation and condensation of the liquid) to quickly conduct heat. A general heat pipe consists of a tube shell, a liquid wick, and an end cap. The inside of the heat pipe is pumped into a negative pressure state and filled with a suitable liquid, which has a low boiling point and is easy to volatilize. The tube wall has a liquid wick, which is made of a capillary porous material. One end of the heat pipe is the evaporation end, and the other end is the condensation end. When one end of the heat pipe is heated, the liquid in the capillary tube quickly vaporizes, and the steam flows to the other end under the power of heat diffusion, and condenses at the cold end to release heat. The liquid then flows back to the evaporation end along the porous material by capillary action, and the cycle continues until the temperatures at both ends of the heat pipe are equal (at this time, the steam heat diffusion stops). This cycle is fast, and heat can be conducted continuously.

[0026] When the electric vehicle no longer needs the heat exchange provided by the external fluid, the buffer chamber is evacuated through the connecting pipe to suck out the external cold fluid or hot fluid, and finally the connecting valve is closed, thereby realizing the recycling of the external fluid without leaving any adverse effects on the electric vehicle.

[0027] Therefore, the present invention aims at the demand for rapid activation of electric vehicle battery chassis assembly, electric vehicle and use method in response to the demand for rapid activation of electric vehicle charging and long-term parking under adverse climatic conditions such as high or low temperature. The technical solution uses externally provided cold fluid or hot fluid, does not rely on the electric vehicle's own function, and overcomes the problem of insufficient charging and discharging capacity of battery pack under adverse climatic conditions; the refrigeration and heating unit used to prepare external cold fluid or hot fluid can be made larger, and can provide a higher power refrigeration and heating capacity than the electric vehicle's own air conditioning and other refrigeration and heating systems, so it takes effect quickly; the solution uses the buffer cavity that already exists in the total cost of the electric vehicle battery chassis, and only needs to add a one-way exhaust valve and a connecting pipe with a connecting valve at the end to the original buffer cavity, which is simple to modify, has little impact on the original vehicle body, and fully utilizes the original buffer cavity space; relies on heat pipes to achieve high-speed heat exchange between the externally injected fluid and the original coolant of the liquid cooling plate, which takes effect quickly and has high energy efficiency; after the heat exchange is completed, the externally injected fluid is pumped away, and while the liquid is recycled, the original mass distribution of the electric vehicle is not affected. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Schematic diagram of the structure of the chassis assembly of an electric vehicle in an embodiment of the present invention.

[0029] Figure 2 For Figure 1 Based on this, a schematic diagram of the structure of the chassis assembly of the electric vehicle after the top wall 21 of the buffer cavity 2 is hidden.

[0030] Figure 3 For Figure 2 Based on this, a schematic diagram of the structure of the chassis assembly of an electric vehicle after the battery pack 1 is hidden.

[0031] Figure 4 for Figure 1 Schematic diagram of the chassis assembly of an electric vehicle from another perspective.

[0032] Figure 5 Schematic diagram of a device for providing external fluid in an embodiment of the present invention.

[0033] In the figure: 1-battery pack, 2-buffer chamber, 3-one-way exhaust valve, 4-connecting pipe, 5-connecting valve, 6-liquid cooling plate, 7-buffer partition, 8-through hole, 9-heat pipe, 10-main pipe, 11-first branch pipe, 12-second branch pipe, 13-delivery pump, 14-vacuum pump, 15-first valve, 16-second valve, 17-liquid storage chamber, 18-heat exchanger, 19-refrigeration and heating unit, 21-top wall, 22-chassis body. DETAILED DESCRIPTION

[0034] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0035] Figure 1 In the electric vehicle battery chassis assembly, the chassis body 22 provides accommodation and support functions for the remaining components of the electric vehicle battery chassis assembly. A buffer cavity 2 is provided on each of the left and right sides of the corresponding vehicle body. The top of the buffer cavity 2 is its top wall 21, and a one-way exhaust valve 3 is provided on the top wall 21.

[0036] like Figures 1 to 4 As shown, the present invention provides an electric vehicle battery chassis assembly, including a battery pack 1 and buffer chambers 2 arranged on both sides of the battery pack 1, wherein:

[0037] The buffer chamber 2 is used to provide buffer protection for the battery pack 1 when the electric vehicle is subjected to external impact, and a one-way exhaust valve 3 and a connecting pipe 4 are provided on the wall surface thereof;

[0038] The one-way exhaust valve 3 only allows the gas in the buffer chamber 2 to be discharged to the external environment, but does not allow the external environment gas to enter the buffer chamber 2 through the one-way exhaust valve 3.

[0039] A connecting valve 5 is disposed at the end of the connecting pipe 4 . When the connecting valve 5 is opened, the external fluid medium can be injected into the buffer chamber 2 through the connecting valve 5 and the connecting pipe 4 in sequence.

[0040] Preferably, the above-mentioned electric vehicle battery chassis assembly further includes a liquid cooling plate 6 for exchanging heat with the battery pack 1 , wherein the liquid cooling plate 6 is filled with a coolant.

[0041] In one embodiment, the coolant fills the flow channel of the liquid cooling plate 6 , and a circulation pump is connected to the flow channel of the liquid cooling plate 6 to provide power for the circulation of the coolant.

[0042] Preferably, in the above-mentioned electric vehicle battery chassis assembly, a buffer partition 7 is further provided in the buffer cavity 2 to provide support to increase the impact resistance of the buffer cavity 2 .

[0043] Preferably, in the above-mentioned electric vehicle battery chassis assembly, the buffer partition 7 is provided with a through hole 8 to facilitate the free flow of the fluid medium injected into the buffer cavity 2 without being blocked by the buffer partition 7 .

[0044] In one embodiment, a plurality of buffer partitions 7 parallel to the width direction of the vehicle are provided in the buffer cavity 2. When the vehicle is subjected to a lateral impact, the buffer cavity 2 and the buffer partitions 7 therein provide a buffering function for the battery pack 1.

[0045] Furthermore, the above-mentioned electric vehicle battery chassis assembly also includes a heat pipe 9 , one end of which is located in the buffer cavity 2 , and the other end is connected to the liquid cooling plate 6 .

[0046] Specifically, when liquid is injected into the buffer cavity 2 , the heat pipe 9 may be submerged in the liquid.

[0047] Preferably, there are multiple heat pipes 9 distributed at different positions, so as to provide a better heat exchange effect and maintain the uniformity of the temperature distribution of the battery pack 1 as much as possible.

[0048] In one embodiment, one end of the heat pipe 9 is welded to the liquid cooling plate 6; in another embodiment, one end of the heat pipe 9 penetrates into the flow channel of the liquid cooling plate 6 and can directly contact the coolant in the flow channel to achieve a better heat exchange effect.

[0049] The present invention also provides an electric vehicle, which is provided with the electric vehicle battery chassis assembly.

[0050] The present invention also provides a method for using the above-mentioned electric vehicle battery chassis assembly. When the electric vehicle is in a parking state and its own thermal management capability cannot meet the cooling or heating requirements of its battery pack 1, the connecting valve 5 is opened, and the external cold fluid or hot fluid is injected into the buffer chamber 2 in turn through the connecting valve 5 and the connecting pipe 4; this is maintained for a certain period of time, and when the electric vehicle no longer needs the heat exchange provided by the external fluid, the buffer chamber 2 is vacuumed through the connecting pipe 4 to suck out the external cold fluid or hot fluid, and finally the connecting valve 5 is closed.

[0051] Preferably, in the method for using the electric vehicle battery chassis assembly, the cold fluid or hot fluid is water.

[0052] Preferably, in the method for using the electric vehicle battery chassis assembly, the temperature of the cold fluid when injected is between 5°C and 25°C, and the temperature of the hot fluid when injected is between 35°C and 55°C.

[0053] Preferably, in the method of using the battery chassis assembly of an electric vehicle, when the buffer chamber 2 is filled with an external cold fluid or hot fluid, the coolant in the liquid cooling plate 6 is in a circulating flow state.

[0054] In one embodiment, when the buffer chamber 2 is filled with external cold fluid or hot fluid, the electric vehicle thermal management system operates the circulation pump to allow the coolant in the liquid cooling plate 6 to flow, thereby achieving better heat exchange and temperature equalization effects, while the electric vehicle's onboard air conditioner, PTC heating element and other cooling and heating equipment do not operate.

[0055] As attached Figure 5 As shown, in order to realize the injection of external cold fluid or hot fluid, it is necessary to rely on ground facilities arranged near the parking space. The ground facilities rely on the cooling and heating unit 19 to provide cold source and heat source for the liquid in the liquid storage chamber 17, and the heat exchange between the two is completed by the heat exchanger 18.

[0056] When the electric vehicle needs heat exchange provided by external fluid, the free end of the main pipe 10 is connected to the connecting valve 5, and the connecting valve 5 is opened; when external injection of cold fluid is required, the cooling and heating unit 19 is operated in the cooling mode, the first valve 15 is opened, the second valve 16 is closed, the delivery pump 13 is started, and the liquid in the liquid storage chamber 17 is injected into the buffer chamber 2; when external injection of hot fluid is required, the cooling and heating unit 19 is operated in the heating mode, the first valve 15 is opened, the second valve 16 is closed, the delivery pump 13 is started, and the liquid in the liquid storage chamber 17 is injected into the buffer chamber 2.

[0057] When the electric vehicle no longer needs heat exchange provided by the external fluid, the first valve 15 is closed, the second valve 16 is opened, the vacuum pump 14 is started, the liquid in the buffer chamber 2 is pumped back to the liquid storage chamber 17, and finally the connecting valve 5 is closed to detach the free end of the main pipe 10 from the connecting valve 5.

[0058] Preferably, in order to control the injection amount of the external liquid, a monitoring instrument ( Figure 5 (not shown), the monitoring instrument is a flow meter and / or a pressure gauge. In one embodiment, a flow meter is provided near the free end of the main pipe 10, and when the injection or withdrawal flow of the liquid reaches a preset flow threshold, the injection or withdrawal is stopped. In another embodiment, a pressure gauge is provided near the free end of the main pipe 10, and when the pressure value exceeds its maximum threshold, the injection is stopped; when the pressure value is lower than its minimum threshold, the withdrawal is stopped.

[0059] Preferably, according to the climate characteristics of the area, the liquid in the liquid storage chamber 17 is pre-cooled and pre-heated in advance, so that it has the ability to immediately inject cold fluid or hot fluid into the buffer chamber 2 at any time, thereby ensuring rapid effectiveness. In one embodiment, if the area is in an extremely hot temperature period, the liquid in the liquid storage chamber 17 always remains in a cold fluid state during this period; in another embodiment, if the area is in an extremely cold temperature period, the liquid in the liquid storage chamber 17 always remains in a hot fluid state during this period.

[0060] The ground facilities that provide external cold fluid or hot fluid rely on power grid power supply, so their operation is not affected by the external environment.

[0061] It should be noted that the buffer chamber 2 is a closed structure, so as to facilitate vacuuming to suck out external fluid. The position and orientation of the one-way exhaust valve 3, the connecting pipe 4 and the connecting valve 5 can be flexibly arranged according to the specific needs of the vehicle body design.

[0062] Preferably, the one-way exhaust valve 3 is disposed on the top wall 21 of the buffer chamber 2, thereby ensuring that the one-way exhaust valve 3 is at the highest possible position to facilitate the exhaust of the gas originally retained in the buffer chamber 2 during the external liquid injection process.

[0063] A hole needs to be opened on the wall of the buffer cavity 2 to facilitate the heat pipe 9 to pass through the wall and connect to the liquid cooling plate 6. Sealant is applied between the heat pipe 9 and the hole wall. The gap between the battery pack 1 and the buffer cavity 2 is filled with thermally conductive glue.

[0064] Example

[0065] Please refer to Figures 1 to 5 More specific embodiments are understood.

[0066] Example 1

[0067] At noon on a midsummer day, the ambient temperature was 46°C. An electric car driven by a ternary lithium-ion battery pack 1 ran out of power and drove into a parking space for fast charging. There is a ground facility for providing external fluid near the parking space. The ground facility quickly fills the buffer chamber 2 of the electric car with cold fluid, so that the temperature of the battery pack 1 quickly drops to a reasonable range and is maintained, ensuring that the battery quickly meets the temperature conditions required for the fast charging process, so that the battery pack 1 can be fast charged safely, stably and efficiently. After charging is completed, the cold fluid injected into the buffer chamber 2 is withdrawn.

[0068] Example 2

[0069] On a cold winter morning, the ambient temperature was 2°C, and an electric car driven by a lithium iron phosphate lithium-ion battery pack 1 had been parked overnight. The owner wanted to start the vehicle and drive away as soon as possible, so he used the ground facilities near the parking space for providing external fluid to quickly fill the buffer chamber 2 of the electric car with hot fluid, which quickly increased the temperature of the battery pack 1, reduced the internal resistance of the battery, and improved the battery discharge capacity to meet the vehicle's need to drive as quickly as possible. After a period of time, the temperature of the battery pack 1 rose to a normal value, the hot fluid injected into the buffer chamber 2 was withdrawn, and the vehicle drove away.

[0070] In the above embodiment of the present invention, in view of the demand for rapid activation of electric vehicles after charging and long-term parking under adverse climatic conditions such as high or low temperatures, a technical solution of an electric vehicle battery chassis assembly, an electric vehicle and a method of use is proposed. The technical solution uses externally provided cold fluid or hot fluid, does not rely on the electric vehicle's own functions, and overcomes the problem of insufficient charging and discharging capacity of the battery pack 1 under adverse climatic conditions; the refrigeration and heating unit 19 used to prepare the external cold fluid or hot fluid can be made larger, and can provide a higher power refrigeration and heating capacity than the electric vehicle's own air conditioning and other refrigeration and heating systems, so it takes effect quickly; the solution uses the buffer chamber 2 that already exists in the total cost of the electric vehicle battery chassis, and only needs to add a one-way exhaust valve 3 and a connecting pipe 4 with a connecting valve 5 at the end to the original buffer chamber 2, which is simple to modify, has little impact on the original vehicle body, and fully utilizes the space of the original buffer chamber 2; relies on the heat pipe 9 to achieve high-speed heat exchange between the externally injected fluid and the original coolant of the liquid cooling plate 6, takes effect quickly, and has high energy efficiency; after the heat exchange is completed, the externally injected fluid is pumped away, and while the liquid is recycled, the original mass distribution of the electric vehicle is not affected.

Claims

1. An electric vehicle battery chassis assembly, characterized in that: It comprises a battery pack (1) and a buffer cavity (2) arranged on both sides of the battery pack (1), wherein: The buffer chamber (2) is used to provide buffer protection for the battery pack (1) when the electric vehicle is subjected to external impact, and a one-way exhaust valve (3) and a connecting pipe (4) are provided on the wall surface of the buffer chamber (2); A connecting valve (5) is provided at the end of the connecting pipe (4). When the connecting valve (5) is opened, the external fluid medium can be injected into the buffer chamber (2) through the connecting valve (5) and the connecting pipe (4) in sequence.

2. The electric vehicle battery chassis assembly according to claim 1, characterized in that: It also includes a liquid cooling plate (6) for exchanging heat with the battery pack (1), wherein the liquid cooling plate (6) is filled with cooling liquid.

3. The electric vehicle battery chassis assembly according to claim 1, characterized in that: A buffer partition (7) is also provided in the buffer cavity (2) for providing support so as to increase the impact resistance of the buffer cavity (2).

4. The electric vehicle battery chassis assembly according to claim 3, characterized in that: The buffer partition (7) is provided with a through hole (8).

5. The electric vehicle battery chassis assembly according to claim 1 or 2, characterized in that: The electric vehicle battery chassis assembly further comprises a heat pipe (9), one end of the heat pipe (9) being located in the buffer cavity (2) and the other end being connected to the liquid cooling plate (6).

6. An electric vehicle, characterized in that: An electric vehicle battery chassis assembly is provided according to any one of claims 1 to 5.

7. A method for using the electric vehicle battery chassis assembly according to any one of claims 1 to 5, characterized in that: When the electric vehicle is in a parking state and its own thermal management capability cannot meet the cooling or heating requirements of its battery pack (1), the connecting valve (5) is opened, and an external cold fluid or hot fluid is injected into the buffer chamber (2) through the connecting valve (5) and the connecting pipe (4) in sequence; this is maintained for a certain period of time, and when the electric vehicle no longer needs the heat exchange provided by the external fluid, the buffer chamber (2) is evacuated through the connecting pipe (4) to suck out the external cold fluid or hot fluid, and finally the connecting valve (5) is closed.

8. The method for using the electric vehicle battery chassis assembly according to claim 7, characterized in that: The cold fluid or the hot fluid is water.

9. The method for using the electric vehicle battery chassis assembly according to claim 7, characterized in that: The temperature of the cold fluid when injected is between 5°C and 25°C, and the temperature of the hot fluid when injected is between 35°C and 55°C.

10. The method for using the electric vehicle battery chassis assembly according to claim 7, characterized in that: When the buffer chamber (2) is filled with external cold fluid or hot fluid, the cooling liquid in the liquid cooling plate (6) is in a circulating flow state.

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