CN113097594A

CN113097594A - Lithium ion battery thermal management system and method based on movable fins and phase-change material

Info

Publication number: CN113097594A
Application number: CN202110344074.7A
Authority: CN
Inventors: 石泳; 康杭; 陈冠一
Original assignee: University of Nottingham Ningbo China
Current assignee: University of Nottingham Ningbo China
Priority date: 2021-03-31
Filing date: 2021-03-31
Publication date: 2021-07-09
Anticipated expiration: 2041-03-31
Also published as: CN113097594B

Abstract

A lithium ion battery thermal management system and a method based on movable fins and phase-change materials can perform thermal management on the operation of lithium ion batteries according to different working temperatures of the lithium ion batteries: namely, when the lithium ion battery works at medium temperature, the battery temperature reaches the melting point of the phase change material, and the phase change material converts the battery heat into self latent heat for storage through solid-liquid phase change; after the phase-change material is completely liquefied, the heat management system drives the fins to be in contact with the surfaces of the battery monomers, heat is conducted through the fins, convection of surrounding refrigerants is conducted, and heat absorption of the liquid phase-change material is assisted to conduct high-temperature heat dissipation; when the battery stops working and the temperature of the battery begins to drop and approaches the melting point of the phase-change material, the heat management system folds the fins back to separate the fins from the surface of the battery monomer, thereby slowing down the external dissipation of the phase-change material and the heat in the battery and preventing the battery pack from dropping too fast in a low-temperature environment. The design can effectively ensure that the lithium ion battery obtains ideal operation temperature and surface temperature difference under different working temperatures.

Description

Lithium ion battery thermal management system and method based on movable fins and phase-change material

Technical Field

The invention relates to the technical field of battery thermal management, in particular to a lithium ion battery thermal management system and method based on movable fins and a phase-change material.

Background

At present, the working temperature and the surface temperature distribution of the lithium ion battery can greatly affect the performance and the service life of the lithium ion battery, and further directly relate to the running cost and the stability of related electric automobiles. Therefore, the normal use and safe operation of such batteries place high demands on their operating temperature. Specifically, a complex electrochemical reaction occurs in the lithium ion battery during charging and discharging processes, so that a large amount of heat is rapidly generated in the lithium ion battery, and the temperature of the battery is increased, thereby reducing the performance of the battery. For example, the cycle life of some lithium-based batteries decays by more than half with repeated charging at ambient temperature of 50 ℃. Moreover, rapid heat generation and temperature rise can also cause combustion and explosion of lithium ion batteries. On the other hand, with the development and increasing use requirements of electric vehicles, high-rate charging and discharging of power lithium ion batteries become more and more common. Therefore, it is highly desirable to improve the heat dissipation efficiency of the power battery pack and rapidly dissipate a large amount of heat generated during the charging and discharging of the battery at a high rate. In addition, lithium ion batteries are also sensitive to low temperature operating environments. When the temperature is lower than-30 c, the chemical reaction inside the battery is slowed down and the electrolyte conductivity is also decreased. This will result in a reduction in battery capacity and even an overall failure of the battery. In view of this, the lithium ion battery thermal management design must cool the battery body in time under the high temperature condition; meanwhile, when the ambient temperature is too low, the battery needs to be effectively insulated. The temperature of the battery is controlled within a reasonable range all the time, and the charging and discharging performance of the power battery is ensured.

Currently, conventional lithium ion battery thermal management methods can be roughly divided into three types: air thermal management, liquid thermal management, and phase change material thermal management. The operation mode is mainly aimed at the high-temperature cooling of the battery (pack). Air thermal management is primarily the driving of air flow between lithium ion batteries to dissipate battery heat into the surrounding environment. The mode is low in cost and simple to install and maintain. The application is the most extensive at present. The liquid heat management system is an improved mode which is provided aiming at the problems that the air heat exchange coefficient is low and the large temperature difference in the battery pack cannot be effectively eliminated. It directly uses the liquid with the heat transfer coefficient higher than that of air to realize better cooling effect. However, if the liquid working substance is electrically conductive and the system is unable to completely circumvent liquid leakage, the liquid thermal management system may cause a short circuit in the cell during use. If a liquid with high insulating properties is used, the viscosity tends to be high, resulting in a high flow resistance which increases the operating costs of the associated thermal management system. Phase change material thermal management is a new type of thermal management that has been rapidly developed in recent years. The aim of cooling the pool body is realized by absorbing the heat of the battery contacted with the solid phase change material through the liquefaction of the solid phase change material. It is worth mentioning that the absorbed battery waste heat will be stored in the form of latent heat in the phase change material. In the subsequent low-temperature environment, the part of heat is released in a liquid phase-change material solidification mode, so that the temperature of the tank body is maintained, and the low-temperature operation performance of the tank body is improved. The phase-change material heat management system is different from an air and liquid heat management system, an additional refrigerant flow channel and an external circulation loop do not need to be designed, and the system is more compact and simpler.

However, the existing phase-change materials have limited liquid-solid phase-change latent heat, small heat conductivity coefficient and limited quantity of the phase-change materials stored in the system. Under the conditions of high temperature and large current charging and discharging, when all the phase-change materials are liquefied, the cooling capacity of a thermal management system is greatly reduced, and the batteries cannot be effectively cooled and controlled. In this regard, some prior designs have added a number of secondary structures that enhance heat transfer. For example, chinese patent publication No. CN108199114B discloses "a battery thermal management system, a control method thereof, and a vehicle air conditioning system". The first heat storage device in the battery heat management system comprises a battery pack and filled phase-change materials inside the first heat storage device. In order to improve the heat transfer efficiency of the first heat storage device, fins and heat conducting grooves are further arranged in the first heat storage device. It is emphasized that the above-mentioned means for enhancing heat transfer are very disadvantageous for the thermal insulation protection required for the operation of the battery under low temperature conditions. Therefore, how to develop a system which is efficient, compact and portable and meets the high, medium and low temperature working heat management requirements of the lithium ion battery based on the specific thermophysical properties of the phase-change material is a core problem in the current heat management research and development of the lithium ion battery of the electric automobile.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides the lithium ion battery thermal management system and method based on the movable fins and the phase-change material, and solves the technical problem that the conventional lithium ion battery thermal management system cannot give consideration to different thermal requirements of the lithium ion battery during high, medium and low temperature work.

In order to achieve the purpose, the invention is realized by the following technical scheme:

the invention provides a lithium ion battery thermal management system based on movable fins and a phase-change material, which comprises a battery outer shell, a battery inner shell, a lithium ion battery pack, the movable fins, the phase-change material, a driving device, a temperature detection unit and a controller, wherein the battery inner shell is arranged in the battery outer shell; the lithium ion battery pack is arranged on the inner side of the battery inner shell and is electrically connected with the controller, the lithium ion battery pack is composed of two rows of a plurality of battery monomers arranged side by side, and two adjacent battery monomers are arranged at intervals; the phase-change material is filled in the battery inner shell; a heat dissipation channel is formed between the battery inner shell and the battery outer shell, and the driving device is arranged in the heat dissipation channel and is electrically connected with the controller; the temperature detection unit is arranged on the inner side of the battery inner shell and is electrically connected with the controller;

at least one movable fin is arranged on one side, facing the battery inner shell, of each battery monomer, and the movable fins are hinged with the inner wall of the battery inner shell through first rotating shafts; the driving device is in transmission connection with the first rotating shaft and is used for driving the movable fin to rotate along with the first rotating shaft; the arrangement positions of the movable fins at least comprise a heat conduction position and a heat resistance position; when the movable fins are located at the heat conduction position, one ends, far away from the first rotating shaft, of the movable fins are abutted to the outer wall of the corresponding battery monomer, so that the heat transfer efficiency of the corresponding battery monomer is improved; when the movable fins are located at the heat resistance positions, the movable fins are attached to the inner wall of the battery inner shell so as to reduce the external dissipation of the heat inside the corresponding battery monomer and the surrounding phase-change material.

Optionally, battery case both sides are equipped with first ventilation hole and second ventilation hole respectively, establish the air inlet unit in the first ventilation hole, establish the air-out unit in the second ventilation hole, the air inlet unit with the air-out unit is connected with the controller electricity respectively.

Optionally, a heating unit is arranged on one side, facing the air inlet unit, of the outer portion of the battery inner shell, so that the lithium ion battery pack can be additionally supplied with heat under the low-temperature working condition, and the heating unit is electrically connected with the controller.

Optionally, the air outlet unit is preferably an electric louver.

Optionally, the surface of the movable fin is provided with a plurality of through holes to leave a flow channel after the phase change material is liquefied.

Optionally, at least one first in-place buffer mechanism is correspondingly arranged on each movable fin to ensure that the movable fin is abutted against the outer wall of the corresponding battery cell; the first in-place buffer mechanism comprises a sliding sheet, a sliding rod, a compression spring, a limiting block and an anti-falling nut; the sliding sheet is connected with one side of the corresponding battery monomer, which faces the battery inner shell in a sliding manner; a sliding rod is arranged on one side of the sliding sheet, which is far away from the corresponding movable fin, and the sliding rod penetrates through the limiting block and is in threaded connection with the anti-falling nut; the limiting block is arranged on one side, facing the battery inner shell, of the battery monomer; the compression spring is clamped between the sliding piece and the limiting block, and the compression spring is sleeved on the periphery of the sliding rod.

Optionally, each movable fin is correspondingly provided with at least one second in-place buffer mechanism, the second in-place buffer mechanism is arranged on the inner wall of the inner shell of the battery, the first in-place buffer mechanism and the second in-place buffer mechanism are respectively arranged on two sides of the corresponding movable fin, and the second in-place buffer mechanism at least comprises an elastic pad.

Optionally, the drive means comprises a rotary motor, a dual-toothed rack, a drive gear and a first driven gear; the battery inner shell is formed by a first shell wall, a second shell wall, a third shell wall and a fourth shell wall in a surrounding mode, a double-tooth-surface rack is connected to the outer side of the first shell wall in a sliding mode, a first tooth surface is arranged on one side, facing a heat dissipation channel, of the double-tooth-surface rack, and a second tooth surface is arranged on one side, facing a battery pack, of the double-tooth-surface rack; the rotating motor is arranged in the heat dissipation channel, a driving gear is sleeved on the periphery of an output shaft of the rotating motor, and the driving gear is in meshing transmission with the first tooth surface; and the peripheries of the top ends of all the first rotating shafts on one side of the first shell wall are sleeved with first driven gears, and all the first driven gears are respectively in meshing transmission with the second tooth surface.

Optionally, a combined rack is slidably connected to the outside of the second casing wall, and the combined rack comprises a first rack and a second rack; the first rack is connected with the outer side of the second shell wall in a sliding mode, and the first rack is flush with the double-tooth-surface rack; a second rack is arranged on the top surface of one end, close to the double-toothed-surface rack, of the first rack in an extending manner; the included angle department of first conch wall and second conch wall is provided with the second pivot, second pivot top periphery cover is equipped with second driven gear and third driven gear, second driven gear and second tooth face meshing transmission, third driven gear is located second driven gear top and meshes the transmission with the second rack.

In a second aspect of the present invention, there is provided a management method for a lithium ion battery thermal management system based on a movable fin and a phase change material, including:

before the lithium ion battery pack starts to work, the temperature detection unit detects the real-time temperature inside the battery inner shell discontinuously and transmits the real-time temperature to the controller, and the controller makes the following judgment based on the received real-time temperature:

when the real-time temperature is higher than a first preset temperature, the controller detects the current position state of the movable fin, if the movable fin is located at a heat conduction position, the movable fin is controlled to keep the current position state, and if the movable fin is located at a heat blocking position, the driving device is controlled to drive the movable fin to rotate to the heat conduction position;

when the real-time temperature is less than or equal to a first preset temperature, controlling the movable fin to keep the current position state;

during the operation of the lithium ion battery pack, the temperature detection unit continuously detects the real-time temperature inside the battery inner shell and transmits the real-time temperature to the controller, and the controller makes the following judgment based on the received real-time temperature:

when the real-time temperature is continuously increased to be higher than a first preset temperature, the controller detects the current position state of the movable fin, if the movable fin is located at a heat conduction position, the movable fin is controlled to keep the current position state, and if the movable fin is located at a heat blocking position, the driving device is controlled to drive the movable fin to rotate to the heat conduction position;

when the real-time temperature is continuously reduced to be lower than a first preset temperature, the controller detects the current position state of the movable fin, if the movable fin is at a heat resistance position, the movable fin is controlled to keep the current position state, and if the movable fin is at a heat conduction position, the driving device is controlled to drive the movable fin to rotate to the heat resistance position;

when the lithium ion battery pack finishes working, the temperature detection unit discontinuously detects the real-time temperature in the battery inner shell and transmits the real-time temperature to the controller, and the controller makes the following judgment based on the received real-time temperature:

when the real-time temperature is higher than a first preset temperature, the controller detects the current position state of the movable fin, if the movable fin is at a heat resistance position, the movable fin is controlled to keep the current position state, and if the movable fin is at a heat conduction position, the driving device is controlled to drive the movable fin to rotate to the heat resistance position;

the first preset temperature is higher than the melting point temperature of the phase-change material by 5-10 ℃.

According to the technical scheme, the invention has the beneficial effects that:

1) the lithium ion battery can be subjected to proper thermal management according to different working environment temperatures: namely, when the lithium ion battery works at medium temperature, the battery temperature reaches the melting point of the phase change material, and the phase change material converts the battery heat into self latent heat for storage through solid-liquid phase change; after the phase-change material is completely liquefied, the fins are driven to be in contact with the surfaces of the battery monomers, heat is conducted through the fins, convection is conducted through surrounding refrigerants (air circulating in a heat dissipation channel), and heat absorption is assisted by the liquid phase-change material to conduct high-temperature heat dissipation; when the battery stops working and the temperature of the battery begins to drop and approaches the melting point of the phase-change material, the driving fins are separated from the surface of the battery monomer, the outward dissipation of heat inside the cell body and the phase-change material is slowed down, and the temperature of the battery is prevented from dropping too fast in a low-temperature environment. The design can effectively ensure that the lithium ion battery obtains ideal working temperature and surface temperature difference under different working conditions.

2) The use of the openable and closable fin structure can continuously maintain high-efficiency heat dissipation efficiency after the phase-change material is completely liquefied, and is suitable for working conditions of high external environment temperature or high-rate work of batteries.

3) The use of the openable and closable fin structure can close all unfolded fins before the phase-change material is not solidified, slow down the external dissipation of the heat inside the battery and the phase-change material, and is suitable for the heat preservation protection of the battery after the external environment temperature is rapidly reduced, so as to prevent the cold start of the battery.

4) The air cooling system formed by the air inlet unit, the air outlet unit and the heat dissipation channel can further improve the heat dissipation efficiency according to actual needs under the condition that the phase change material is completely liquefied and the fins are opened. The method is suitable for the working condition that the battery works in a hot environment or under a large load.

5) The lithium battery can be additionally supplied with heat under the conditions that the phase-change material is completely solidified and the fins are closed by using the electric heating unit. The cold storage battery is suitable for the working condition that the battery is placed in a cold environment for a long time.

Of course, it is not necessary for any one product in which the invention is practiced to achieve all of the above-described technical effects simultaneously.

Drawings

In order to more clearly illustrate the detailed description of the invention or the technical solutions in the prior art, the drawings that are needed in the detailed description or the prior art description will be briefly described below. Throughout the drawings, like elements or portions are generally identified by like reference numerals. In the drawings, elements or portions are not necessarily drawn to scale.

FIG. 1 is a top view of a lithium-ion battery thermal management system based on movable fins and a phase change material;

FIG. 2 is a schematic perspective view of a lithium ion battery thermal management system based on movable fins and a phase change material;

FIG. 3 is an enlarged schematic view at A in FIG. 2;

FIG. 4 is an enlarged schematic view at B of FIG. 3;

FIG. 5 is a schematic view of the second in-position damping mechanism;

FIG. 6 is a schematic view of the installation of the drive device;

FIG. 7 is an enlarged schematic view at C of FIG. 6;

FIG. 8 is an enlarged schematic view at D of FIG. 6;

FIG. 9 is an enlarged schematic view at E in FIG. 6;

reference numerals:

1-a battery outer shell, 2-a battery inner shell, 3-a lithium ion battery pack, 4-a movable fin, 5-a phase change material, 6-a driving device, 7-a temperature detection unit, 8-a first in-place buffer mechanism and 9-a second in-place buffer mechanism;

11-an air inlet unit, 12-an air outlet unit, 13-a heating unit, 21-a first shell wall, 22-a second shell wall, 23-a third shell wall, 24-a fourth shell wall, 31-a battery monomer, 41-a first rotating shaft, 61-a rotating motor, 62-a double-tooth-surface rack, 63-a driving gear, 64-a first driven gear, 65-a second rotating shaft, 66-a combined rack, 67-a second driven gear, 68-a third driven gear, 81-a sliding sheet, 82-a sliding rod, 83-a compression spring, 84-a limiting block and 85-an anti-falling nut;

621-first flank, 622-second flank, 661-first rack, 662-second rack.

Detailed Description

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The following examples are only for illustrating the technical solutions of the present invention more clearly, and therefore are only examples, and the protection scope of the present invention is not limited thereby.

Referring to fig. 1, the present invention provides a lithium ion battery thermal management system based on a movable fin 4 and a phase change material 5, which includes a battery case 1, a battery case 2, a lithium ion battery pack 3, a movable fin 4, a phase change material 5, a driving device 6, a temperature detection unit 7, and a controller. The lithium ion battery pack 3 is arranged on the inner side of the battery inner shell 2 and is electrically connected with the controller, the lithium ion battery pack 3 is composed of two rows of a plurality of battery monomers 31 arranged side by side, and every two adjacent battery monomers 31 are arranged at intervals. Obviously, the lithium ion battery pack 3 may also be provided with only a single battery cell 31, or only a row of battery cells 31, and the arrangement of the movable fins 4 may be satisfied. The phase change material 5 is filled in the battery inner casing 2, specifically, in the areas between two adjacent battery cells 31 and between the battery cells 31 and the battery inner casing 2. A heat dissipation channel is formed between the battery inner shell 2 and the battery outer shell 1. On one hand, the heat dissipation channel is communicated with the outside to form a refrigerant loop so as to accelerate heat dissipation; on the other hand, the heat dissipation channel also serves as a space for mounting components such as the driving device 6 and the heating unit 13. The temperature detection unit 7 is arranged on the inner side of the battery inner shell 2 and electrically connected with the controller so as to detect the internal temperature of the battery inner shell 2 discontinuously or continuously according to the working state of the lithium ion battery pack and feed back the real-time temperature to the controller in the form of an electric signal.

Each battery unit 31 is provided with at least one movable fin 4 towards one side of the battery inner casing 2, and the movable fin 4 is hinged with the inner wall of the battery inner casing 2 through a first rotating shaft 41. Referring to fig. 1, in the present embodiment, the battery cell 31 is a rectangular parallelepiped, two movable fins 4 are disposed at intervals in the length direction, and only one movable fin 4 is disposed in the width direction. The driving device 6 is disposed in the heat dissipation channel and electrically connected to the controller, and the driving device 6 is in transmission connection with the first rotating shaft 41 and is configured to drive the movable fin 4 to rotate along with the first rotating shaft 41. The arrangement positions of the movable fins 4 at least include a heat conduction position and a heat resistance position. When the movable fin 4 is located at the heat conducting position, one end of the movable fin 4, which is far away from the first rotating shaft 41, is abutted against the outer wall of the corresponding battery cell 31, so as to improve the heat transfer efficiency of the corresponding battery cell 31; when the movable fins 4 are located at the heat blocking position, the movable fins 4 are attached to the inner wall of the battery inner casing 2, so that the outward dissipation of the heat inside the corresponding battery cells 31 and the surrounding phase change material 5 is reduced. Preferably, the surface of the movable fin 4 is provided with a plurality of through holes to leave a flow channel after the phase change material 5 is liquefied, so as to reduce the resistance of the movable fin 4 when moving between the heat conduction position and the heat resistance position.

The battery thermal management system can perform proper thermal management on the operation of the lithium ion battery according to different working environment temperatures: namely, when the lithium ion battery works at medium temperature, the battery temperature reaches the melting point of the phase change material 5, and the phase change material 5 converts the battery heat into self latent heat for storage through solid-liquid phase change; after the phase-change material 5 is completely liquefied, the fins are driven to be in contact with the surface of the battery monomer 31, heat conduction is carried out through the fins, convection is carried out on surrounding refrigerants (air circulating in a heat dissipation channel), and heat absorption is carried out by the aid of the liquid phase-change material to carry out high-temperature heat dissipation; when the battery stops working and the temperature of the battery begins to drop and approaches the melting point of the phase-change material 5, the driving fin is separated from the surface of the battery monomer 31, so that the outward dissipation of the heat inside the corresponding battery monomer 31 and the surrounding phase-change material 5 is slowed down, and the battery is prevented from being too fast cooled in a low-temperature environment. The design can effectively ensure that the lithium ion battery obtains ideal working temperature and surface temperature difference under different working conditions, and improves the running stability of the related electric automobile. The openable and closable fin structure is used, so that the efficient heat dissipation efficiency can be continuously maintained after the phase change material 5 is completely liquefied, and the heat dissipation structure is suitable for the working conditions of high external environment temperature or high-rate work of a battery; the use of the openable and closable fin structure can close all the unfolded fins before the phase-change material 5 is not solidified, slow down the external dissipation of the heat inside the lithium ion battery pack 3 and the phase-change material 5, and is suitable for the heat preservation protection of the battery after the external environment temperature is rapidly reduced, so as to prevent the cold start of the battery.

As a further improvement to the above scheme, two sides of the battery case 1 are respectively provided with a first ventilation hole and a second ventilation hole, an air inlet unit 11 is arranged in the first ventilation hole, an air outlet unit 12 is arranged in the second ventilation hole, and the air inlet unit 11 and the air outlet unit 12 are respectively electrically connected with the controller. The air inlet unit 11 is preferably a heat dissipation fan, and the heat dissipation fan sends outside air into the heat dissipation channel and can control the air inlet speed; the air outlet unit 12 is preferably an electric louver which discharges air absorbed by the heat dissipation channel, and the opening and the air outlet direction of the electric louver can be adjusted. The air inlet unit 11, the air outlet unit 12 and the heat dissipation channel form an air cooling system, and the heat dissipation efficiency can be further improved according to actual needs under the conditions that the phase-change material 5 is completely liquefied and the fins are opened. The method is suitable for the working condition that the battery works in a hot environment or under a large load.

As a further improvement to the above scheme, a heating unit 13 is arranged on one side of the outside of the battery inner casing 2 facing the air inlet unit 11, and the heating unit 13 is electrically connected with the controller. With the electrical heating unit 13, the lithium battery can be supplied with additional heat with the phase change material 5 fully solidified and the fins closed. The cold storage battery is suitable for the working condition that the battery is placed in a cold environment for a long time. In particular, in order to uniformly and rapidly heat up the lithium ion battery pack 3, when the heating unit 13 is heated, the air intake unit is started to blow air with low power, and the louver is opened at a small angle, so that hot air convection is formed in the heat dissipation channel, and the whole surface of the battery inner case 2 is coated when the hot air flows.

As a further improvement to the above solution, at least one first in-place buffer mechanism 8 is correspondingly arranged on each movable fin 4 to ensure that the movable fin 4 abuts against the outer wall of the corresponding battery cell 31 to ensure the heat transfer efficiency. Referring to fig. 2-4, the first in-place buffer mechanism 8 includes a sliding sheet 81, a sliding rod 82, a compression spring 83, a limiting block 84 and an anti-slip nut 85. The sliding sheet 81 is connected with the corresponding battery monomer 31 in a sliding way towards one side of the battery inner shell 2; the sliding piece 81 is provided with a sliding rod 82 at one side not contacting with the movable fin 4, and the sliding rod 82 penetrates through the limiting block 84 and then is in threaded connection with an anti-falling nut 85; the limiting block 84 is arranged on one side of the battery monomer 31 facing the battery inner shell 2; the compression spring 83 is clamped between the sliding sheet 81 and the limiting block 84, and the compression spring 83 is sleeved on the periphery of the sliding rod 82. Through the sliding connection between the sliding rod 82 and the limiting block 84, the battery monomer 31 shell is always in close contact with the sliding sheet 81 when sliding; the sliding piece 81 is determined to be in close contact with the movable fin 4 by compressing the spring 83. Correspondingly, referring to fig. 5, each movable fin 4 is correspondingly provided with at least one second in-place buffer mechanism 9, the second in-place buffer mechanism 9 is arranged on the inner wall of the battery inner casing 2, the first in-place buffer mechanism 8 and the second in-place buffer mechanism 9 are respectively arranged on two sides of the corresponding movable fin 4, and the second in-place buffer mechanism 9 at least comprises an elastic pad. The movable fin 4 is ensured to rotate in place on one hand by arranging the first in-place buffering mechanism 8 and the second in-place buffering mechanism 9; on the other hand, it is possible to prevent the movable fin 4 from being deformed when the rotation angle of the first rotation shaft 41 exceeds a preset value.

As a further improvement to the above, referring to fig. 6 to 7, the driving device 6 includes a rotating electric machine 61, a double toothed rack 62, a driving gear 63, and a first driven gear 64. The battery inner shell 2 is formed by surrounding a first shell wall 21, a second shell wall 22, a third shell wall 23 and a fourth shell wall 24, a double-tooth-surface rack 62 is connected to the outer side of the first shell wall 21 in a sliding mode, a first tooth surface 621 is arranged on one side, facing a heat dissipation channel, of the double-tooth-surface rack 62, and a second tooth surface 622 is arranged on one side, facing the lithium ion battery pack 3, of the double-tooth-surface rack 62; the rotating motor 61 is arranged in the heat dissipation channel, a driving gear 63 is sleeved on the periphery of an output shaft of the rotating motor 61, and the driving gear 63 is in meshing transmission with the first tooth surface 621; the top end periphery of all the first rotating shaft 41 on one side of the first casing wall 21 is sleeved with a first driven gear 64, and all the first driven gears 64 are respectively in meshing transmission with the second tooth surface 622. The rotating motor 61 drives the double-tooth-surface rack 62 to slide, and the sliding of the double-tooth-surface rack 62 drives the first driven gear 64 to rotate, so that the movable fin 4 is driven to rotate.

As a further improvement to the above solution, referring to fig. 8-9, a combined rack 66 is slidably connected to the outside of the second housing wall 22, and the combined rack 66 includes a first rack 661 and a second rack 662; the first rack 661 is slidably connected to the outside of the second housing wall 22, and the first rack 661 is flush with the double-tooth-surface rack 62; a second rack 662 extends from the top surface of one end of the first rack 661, which is close to the double-tooth-surface rack 62; a second rotating shaft 65 is arranged at the included angle between the first shell wall 21 and the second shell wall 22, a second driven gear 67 and a third driven gear 68 are sleeved on the periphery of the top end of the second rotating shaft 65, the second driven gear 67 is in meshing transmission with a second tooth surface 622, and the third driven gear 68 is positioned above the second driven gear 67 and is in meshing transmission with a second rack 662. Through the combined rack 66 and the second rotating shaft 65, a driving force is obtained from the double-toothed rack 62, the combined rack 66 and the double-toothed rack 62 are ensured to slide at equal intervals, and further, the synchronous rotation of all the movable fins 4 is ensured through one motor.

As a further improvement to the above scheme, the first rotating shaft 41 includes a first rod and a second rod, the first rod is connected to the movable fin 4, the bottom end of the second rod is inserted into the top end of the first rod, and the top end of the second rod is connected to the driven gear 64. The battery inner casing 2 obviously further comprises a top cover plate, in order to facilitate installation, the first rotating shaft 41 is arranged in a split manner, a mounting hole is formed in the top cover plate in advance in a position corresponding to the rotating shaft, and after the first rod body and the movable fin 4 which are located inside the battery inner casing 2 are installed, the second rod body is inserted into the insertion groove of the first rod body from the upper side of the cover plate through the mounting hole. Similarly, the second rotating shaft 65 is also provided separately.

The invention also provides a management method of the lithium ion battery thermal management system based on the movable fins 4 and the phase-change material 5, which comprises the following steps:

before the lithium ion battery pack 3 is started to work, the temperature detection unit 7 detects the real-time temperature inside the battery inner shell 2 discontinuously and transmits the real-time temperature to the controller, and the controller makes the following judgment based on the received real-time temperature:

when the real-time temperature is higher than a first preset temperature, the controller detects the current position state of the movable fin 4, if the movable fin 4 is at a heat conduction position, the movable fin 4 is controlled to keep the current position state, and if the movable fin 4 is at a heat blocking position, the driving device 6 is controlled to drive the movable fin 4 to rotate to the heat conduction position;

when the real-time temperature is less than or equal to a first preset temperature, controlling the movable fin 4 to keep the current position state;

during the operation of the lithium ion battery pack 3, the temperature detection unit 7 continuously detects the real-time temperature inside the battery inner casing 2 and transmits the real-time temperature to the controller, and the controller makes the following determination based on the received real-time temperature:

when the real-time temperature continuously rises to be higher than a first preset temperature, the controller detects the current position state of the movable fin 4, if the movable fin 4 is located at a heat conduction position, the movable fin 4 is controlled to keep the current position state, and if the movable fin 4 is located at a heat resistance position, the driving device 6 is controlled to drive the movable fin 4 to rotate to the heat conduction position;

when the real-time temperature is continuously reduced to be lower than a first preset temperature, the controller detects the current position state of the movable fin 4, if the movable fin 4 is at a heat resistance position, the movable fin 4 is controlled to keep the current position state, and if the movable fin 4 is at a heat conduction position, the driving device 6 is controlled to drive the movable fin 4 to rotate to the heat resistance position;

when the lithium ion battery pack 3 finishes working, the temperature detection unit 7 detects the real-time temperature inside the battery inner shell 2 discontinuously and transmits the real-time temperature to the controller, and the controller makes the following judgment based on the received real-time temperature:

when the real-time temperature is higher than a first preset temperature, the controller detects the current position state of the movable fin 4, if the movable fin 4 is at a heat resistance position, the movable fin 4 is controlled to keep the current position state, and if the movable fin 4 is at a heat conduction position, the driving device 6 is controlled to drive the movable fin 4 to rotate to the heat resistance position;

and when the real-time temperature is less than or equal to a first preset temperature, controlling the movable fin 4 to keep the current position state.

The first preset temperature is higher than the melting point temperature of the phase change material 5 by 5-10 ℃, so that when the movable fin 4 changes the position state, the phase change material 5 is in a completely liquefied state, and the movable fin 4 is prevented from being scratched by the solid phase change material 5, so that the adverse effects of fin deformation, dislocation and reduced efficacy are avoided. Particularly, before the position state of the movable fin 4 is changed each time, the current actual position of the fin needs to be detected, so as to avoid that the fin is blocked when executing the action and even the motor is burnt out due to the instruction error of the preorder program and/or preorder operation error. In one embodiment, the rotating motor 61 is a stepping motor, and when the position detection of the movable fin 4 is performed, the stepping motor rotates by 0.9 degree or 1.8 degrees according to an instruction issued by the controller, and the controller can determine the current actual position state of the movable fin 4 based on the received current change fed back by the stepping motor. In another embodiment, a distance sensor is arranged in the heat dissipation channel, the distance sensor detects the relative position of the double-tooth-surface rack 62 in the heat dissipation channel, and the controller can judge the current actual position state of the movable fin 4 based on an electric signal returned by the distance sensor.

In one embodiment, a management method of a thermal management system disclosed in the present application includes:

when the lithium ion battery does not work, the temperature detection unit 7 detects the real-time temperature of the chamber where the lithium ion battery pack 3 is located discontinuously, and transmits the real-time temperature to the controller, and when the controller judges that the temperature of the phase change material 5 in the lithium ion battery inner shell 2 continuously drops to be close to a melting point, the fins are folded and tightly attached to the inner wall of the battery inner shell 2, so that latent heat stored by the phase change material 5 is prevented from being dissipated to the environment due to the fin structure. The heat will preserve heat to the battery which is not working, preventing it from temperature dropping too fast in low temperature environment. At this time, the heating unit 13, the air inlet unit 11 and the air outlet unit 12 are all in a closed state.

Once the lithium ion battery starts to work, the temperature detection unit 7 continuously detects the temperature of a battery box where the lithium ion battery pack 3 is located and transmits the temperature to the controller, when the controller judges that the working temperature of the lithium ion battery is lower than a second preset temperature, the phase change material is in a solid state, the heating unit 13 is started immediately to heat the phase change material 5 in the battery inner shell 2, and meanwhile, the driving device 6 is controlled to close the shutter to prevent hot air from leaking. And the second preset temperature is the lowest value of the ideal working temperature of the lithium ion battery. At this time, the movable fin 4 should be in a closed state (i.e. at a heat blocking position) all the time, the heat of the inner battery shell 2 heats the lithium ion battery pack 3 through the phase change material 5 until the controller detects that the temperature in the battery box reaches the ideal temperature range of the lithium ion battery, the heating unit 13 is turned off, and at the same time, the driving device 6 is controlled to drive the louver to rotate reversely to reopen the louver, so that the heating process is finished.

On the other hand, when the controller detects that the temperature in the battery box is higher than the first preset temperature, the phase-change material 5 is in a liquid state at the moment, the phase-change material sends an instruction to open the movable fins 4 and the cooling fan, the controller controls the movable fins 4 to be unfolded (namely, located at the heat conduction position), and the outer wall of the battery monomer 31 is connected with the battery inner shell 2, so that the heat transfer efficiency between the lithium ion battery and the battery inner shell 2 is improved. Meanwhile, the controller selects the starting power of the cooling fan according to the current temperature, under the action of the cooling fan, air passes through the surface of the battery inner shell 2, heat on the battery inner shell 2 is taken away through convection heat exchange, and the heated air finally takes the heat out to the surrounding environment through the shutter. Therefore, the purposes of heat dissipation and cooling of the lithium ion battery are achieved by taking the movable fins 4, the phase-change material 5 and air as media. The cooling process is finished after the temperature of the lithium ion battery returns to the ideal range, and the controller turns off the heat dissipation fan and/or folds the movable fins 4 to be attached to the inner wall of the battery inner shell 2.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; such modifications and substitutions do not depart from the spirit and scope of the present invention, and they should be construed as being included in the following claims and description.

Claims

1. The utility model provides a lithium ion battery thermal management system based on movable fin and phase change material which characterized in that: the lithium ion battery pack comprises a battery outer shell (1), a battery inner shell (2), a lithium ion battery pack (3), a movable fin (4), a phase change material (5), a driving device (6), a temperature detection unit (7) and a controller; the lithium ion battery pack (3) is arranged on the inner side of the battery inner shell (2) and is electrically connected with the controller, the lithium ion battery pack (3) is composed of two rows of a plurality of battery monomers (31) which are arranged side by side, and two adjacent battery monomers (31) are arranged at intervals; the phase change material (5) is filled in the battery inner shell (2); a heat dissipation channel is formed between the battery inner shell (2) and the battery outer shell (1) and is used for circulating a refrigerant under a high-temperature working condition; the driving device (6) is arranged in the heat dissipation channel and is electrically connected with the controller; the temperature detection unit (7) is arranged on the inner side of the battery inner shell (2) and is electrically connected with the controller;

at least one movable fin (4) is arranged on one side, facing the battery inner shell (2), of each battery unit (31), and the movable fins (4) are hinged to the inner wall of the battery inner shell (2) through first rotating shafts (41); the driving device (6) is in transmission connection with the first rotating shaft (41) and is used for driving the movable fin (4) to rotate along with the first rotating shaft (41); the arrangement positions of the movable fins (4) at least comprise a heat conduction position and a heat resistance position; when the movable fins (4) are located at the heat conduction position, one ends, far away from the first rotating shafts (41), of the movable fins (4) are abutted against the outer wall of the corresponding battery single body (31) so as to improve the heat transfer efficiency of the corresponding battery single body (31); when the movable fins (4) are located at the heat resistance positions, the movable fins (4) are attached to the inner wall of the battery inner shell (2) so as to slow down the external dissipation of the heat inside the corresponding battery monomer (31) and the surrounding phase-change material (5).

2. The lithium ion battery thermal management system based on movable fins and a phase change material as claimed in claim 1, wherein: battery case (1) both sides are equipped with first ventilation hole and second ventilation hole respectively, establish air inlet unit (11) in the first ventilation hole, establish air-out unit (12) in the second ventilation hole, air inlet unit (11) with air-out unit (12) are connected with the controller electricity respectively.

3. The lithium ion battery thermal management system based on movable fins and a phase change material as claimed in claim 2, wherein: the battery is characterized in that a heating unit (13) is arranged on one side of the outer wall of the battery inner shell (2) facing the air inlet unit (11) so as to supply heat to the lithium ion battery pack (3) additionally under the low-temperature working condition, and the heating unit (13) is electrically connected with the controller.

4. The lithium ion battery thermal management system based on movable fins and a phase change material as claimed in claim 3, wherein: the air outlet unit (12) is preferably an electric shutter.

5. The lithium ion battery thermal management system based on movable fins and a phase change material as claimed in claim 1, wherein: the surface of the movable fin (4) is provided with a plurality of through holes so as to keep a flow channel of the liquefied phase-change material (5).

6. The lithium ion battery thermal management system based on movable fins and a phase change material as claimed in claim 1, wherein: each movable fin (4) is correspondingly provided with at least one first in-place buffer mechanism (8) so as to ensure that the movable fin (4) is abutted against the outer wall of the corresponding battery cell (31); the first in-place buffer mechanism (8) comprises a sliding sheet (81), a sliding rod (82), a compression spring (83), a limiting block (84) and an anti-falling nut (85); the sliding sheet (81) is in sliding connection with one side, facing the battery inner shell (2), of the corresponding battery monomer (31); a sliding rod (82) is arranged on one side, away from the corresponding movable fin (4), of the sliding sheet (81), and the sliding rod (82) penetrates through the limiting block (84) and then is in threaded connection with an anti-falling nut (85); the limiting block (84) is arranged on one side, facing the battery inner shell (2), of the battery monomer (31); the compression spring (83) is clamped between the sliding piece (81) and the limiting block (84), and the periphery of the sliding rod (82) is sleeved with the compression spring (83).

7. The lithium ion battery thermal management system based on movable fins and a phase change material as claimed in claim 1, wherein: every movable fin (4) all correspond and set up at least one second buffer gear (9) that targets in place, second buffer gear (9) that targets in place sets up in battery inner shell (2) inner wall, just first buffer gear (8) that targets in place and second buffer gear (9) branch locate corresponding movable fin's (4) both sides, second buffer gear (9) that targets in place includes the cushion at least.

8. The lithium ion battery thermal management system based on movable fins and a phase change material according to any one of claims 1 to 7, wherein: the driving device (6) comprises a rotating motor (61), a double-toothed rack (62), a driving gear (63) and a first driven gear (64); the battery inner shell (2) is formed by encircling a first shell wall (21), a second shell wall (22), a third shell wall (23) and a fourth shell wall (24), a double-tooth-surface rack (62) is connected to the outer side of the first shell wall (21) in a sliding mode, a first tooth surface (621) is arranged on one side, facing a heat dissipation channel, of the double-tooth-surface rack (62), and a second tooth surface (622) is arranged on one side, facing a lithium ion battery pack (3), of the double-tooth-surface rack (62); the rotating motor (61) is arranged in the heat dissipation channel, a driving gear (63) is sleeved on the periphery of an output shaft of the rotating motor (61), and the driving gear (63) is in meshing transmission with the first tooth surface (621); all the top end peripheries of the first rotating shafts (41) on one side of the first shell wall (21) are sleeved with first driven gears (64), and all the first driven gears (64) are respectively in meshing transmission with second tooth surfaces (622).

9. The movable fin and phase change material based lithium ion battery thermal management system of claim 8, wherein: a combined rack (66) is connected to the outer side of the second shell wall (22) in a sliding mode, and the combined rack (66) comprises a first rack (661) and a second rack (662); the first rack (661) is connected with the outer side of the second shell wall (22) in a sliding mode, and the first rack (661) is flush with the double-tooth-surface rack (62); a second rack (662) extends from the top surface of one end, close to the double-tooth-surface rack (62), of the first rack (661); the included angle department of first conch wall (21) and second conch wall (22) is provided with second pivot (65), second pivot (65) top periphery cover is equipped with second driven gear (67) and third driven gear (68), second driven gear (67) and second flank of tooth (622) meshing transmission, third driven gear (68) are located second driven gear (67) top and with second rack (662) meshing transmission.

10. A method for managing a thermal management system of a lithium ion battery based on movable fins and a phase change material according to any one of claims 1 to 9, comprising:

before the lithium ion battery pack (3) is started to work, the temperature detection unit (7) detects the real-time temperature inside the battery inner shell discontinuously and transmits the real-time temperature to the controller, and the controller makes the following judgment based on the received real-time temperature:

when the real-time temperature is higher than a first preset temperature, the controller detects the current position state of the movable fin (4), if the movable fin (4) is located at a heat conduction position, the movable fin (4) is controlled to keep the current position state, and if the movable fin (4) is located at a heat resistance position, the driving device (6) is controlled to drive the movable fin (4) to rotate to the heat conduction position;

when the real-time temperature is less than or equal to a first preset temperature, controlling the movable fin (4) to keep the current position state;

during the operation of the lithium ion battery pack (3), the temperature detection unit (7) continuously detects the real-time temperature inside the battery inner shell and transmits the real-time temperature to the controller, and the controller makes the following judgment based on the received real-time temperature:

when the real-time temperature is continuously increased to be higher than a first preset temperature, the controller detects the current position state of the movable fin (4), if the movable fin (4) is located at a heat conduction position, the movable fin (4) is controlled to keep the current position state, and if the movable fin (4) is located at a heat resistance position, the driving device (6) is controlled to drive the movable fin (4) to rotate to the heat conduction position;

when the real-time temperature is continuously reduced to be lower than a first preset temperature, the controller detects the current position state of the movable fin (4), if the movable fin (4) is at a heat resistance position, the movable fin (4) is controlled to keep the current position state, and if the movable fin (4) is at a heat conduction position, the driving device (6) is controlled to drive the movable fin (4) to rotate to the heat resistance position;

when the lithium ion battery pack (3) finishes working, the temperature detection unit (7) detects the real-time temperature inside the battery inner shell discontinuously and transmits the real-time temperature to the controller, and the controller makes the following judgment based on the received real-time temperature:

when the real-time temperature is higher than a first preset temperature, the controller detects the current position state of the movable fin (4), if the movable fin (4) is at a heat resistance position, the movable fin (4) is controlled to keep the current position state, and if the movable fin (4) is at a heat conduction position, the driving device (6) is controlled to drive the movable fin (4) to rotate to the heat resistance position;

wherein the first preset temperature is 5-10 ℃ higher than the melting point temperature of the phase-change material (5).