Temperature controlled battery module

Abstract

A temperature controlled battery module (10) comprising: - a battery (12) located immersed inside a liquid tight container (14) and - a radiator (16) located outside the liquid tight container, - a liquid (18) inside the liquid tight container and in the radiator, the battery module (10) comprising at least one inflow path (21) for the liquid to flow from the liquid tight container in to the radiator and at least one outflow path (22) for the liquid to flow out from the radiator and back into the liquid tight container, the battery module (10) further comprising a flow controller (30) configured to control the flow to the radiator from the liquid tight container based on a set temperature.

Description

[0001] Temperature controlled battery module

[0002] Technical field

[0003] The present invention relates to a battery module. In particular the present invention relates to a battery module suitable for use in an electrically driven vehicle such as an electrical moped and other electrically driven vehicles.

[0004] Background

[0005] Batteries used in electrically driven vehicles such as mopeds face several challenges in extreme environments such as cold environments or hot environments. Similar challenges are also present for other types of electrically driven vehicles such as cars and vehicles operating in space and on other planets. For example, the efficiency is typically reduced in cold environments since cold temperatures can significantly reduce battery efficiency, leading to decreased performance and shorter battery life. Other issues include batteries charging in cold weather. Batteries may also consume more energy to maintain optimal performance in cold conditions, leading to quicker depletion. In hot conditions it is a challenge in the opposite way, there might be a challenge to keep the battery at an acceptable temperature since to high temperatures will limit the lifetime and performance of the battery.

[0006] To mitigate the issues with cold environment, the vehicle can be stored in a warmer place, typically indoors. However, it is not always possible to store the vehicle in a warmer place and the battery should therefore be designed to cope with the cold environment.

[0007] To mitigate the issues with hot environment, the vehicle or battery needs improved cooling during battery charging and / or vehicle usage.

[0008] There is a constant desire to improve the efficiency of batteries. Hence there is a need for an improved battery and battery module to cope with for example cold and hot environments. Summary

[0009] It is an object of the present invention to at least partly overcome the above problems, and to provide an improved battery module with liquid cooling. In particular a liquid cooled battery module where the battery cells of the battery are immersed in the liquid.

[0010] This object and I or other is obtained by the battery module as set out in the appended claims.

[0011] In accordance with the invention a battery module is provided. The battery module comprises an immersed battery located inside a liquid tight container and a radiator located outside the liquid tight container. A liquid is provided in the liquid tight container and in the radiator. The battery module further comprises at least one inflow path for the liquid to flow from the liquid tight container in to the radiator and at least one outflow path for the liquid to flow out from the radiator and back into the liquid tight container. Also, the battery module further comprises a flow controller configured to control the flow to the radiator from the liquid tight container based on a set temperature. Hereby flow to an external radiator can be efficiently controlled such that improved operational conditions for the battery can be obtained. The battery can be formed by immersed battery cells where a liquid can be circulated between the battery cells. In particular the flow to the radiator from the liquid tight container based on the temperature of the liquid so as to provide an efficient control of the temperature of the battery.

[0012] In accordance with one embodiment the flow controller is a valve. Hereby a flow control based on natural (Buoyancy-driven) convection can be obtained. In an alternative embodiment the flow controller is a pump that can pump a flow.

[0013] In accordance with some embodiments an insulating layer at least partially covering the outside the liquid tight container is provided. Hereby the liquid tight container can be thermally insulated such that heat is kept within the liquid tight container housing the battery. The insulating layer can for example comprise an insulating material. The insulating layer can also be formed by a vacuum layer.

[0014] In accordance with some embodiments, a controller is provided and configured to control the flow controller. Hereby advanced control schemes for the flow controller can be implemented.

[0015] In accordance with some embodiments, the radiator is thermally insulated from the liquid tight container. Hereby improved thermal management of the battery can be obtained.

[0016] In accordance with some embodiments, the radiator comprises enlargements on at least one outside wall. The enlargements can comprise fins. Also, the radiator can comprise enlargements on at least one inside wall. Hereby an improved heat exchange in the radiator can be obtained.

[0017] In accordance with some embodiments, a heater can be provided in the battery module. Hereby better conditions for the battery can be provided in some scenarios.

[0018] In accordance with some embodiments, a compressible member can be provided in the liquid tight container. Hereby problems related to thermal expansion of the liquid can be mitigated.

[0019] In accordance with some embodiments, a spacer element is located at the bottom side of the battery such that liquid flow from the bottom side of the battery is facilitated. Hereby a flow in a bottom to top direction through cells of the battery can be improved.

[0020] In accordance with some embodiments, a flow controller plate is located at at least one side of the battery such that the flow is directed in an upwards direction. Hereby a flow in a bottom to top direction through cells of the battery can be improved. Brief description of the drawings

[0021] The invention will now be explained more closely by the description of different exemplary embodiments of the invention and with reference to the appended figures.

[0022] Fig. 1 schematically illustrates a battery module in accordance with a first embodiment, Fig. 2 schematically illustrates a part of a battery module in accordance with a second embodiment,

[0023] Detailed description

[0024] Aspects of the present disclosure will be described more fully hereinafter with reference to the accompanying drawings. It is to be understood that the drawings illustrate exemplary embodiments and that components can be added or omitted from the shown embodiments to meet specific implementation needs. Like numbers in the drawings refer to like elements throughout the description.

[0025] In Fig. 1 , a battery module 10 is depicted. The battery module 10 comprises a battery 12 located in a liquid tight container 14. The battery 12 can for example be formed by battery cells such as round or prismatic battery cells. Between the battery cells is a space where a liquid can flow freely. The battery module can further comprise a radiator 16 located outside the liquid tight container 14.

[0026] The liquid tight container 14 is advantageously thermally insulated to keep heat inside the liquid tight container when the battery is not used. For example, and insulating layer at least partially covering the outside the liquid tight container can be provided. In particular the entire liquid container can be provided with a thermally insulating layer.

[0027] The insulating layer can for example comprise an insulating material and / or the insulating layer can comprise a vacuum layer. The insulation layer can help to maintain the battery at an optimum temperature in cold climates. After the use of the battery module the created waste heat can be stored within the isolated container for several hours maintaining a suitable operating temperature for the battery module for a prolonged time period.

[0028] The battery module 10 further comprises a liquid 18. The liquid 18 is used for temperature control of the battery 12. The liquid 18 can be circulated between the liquid tight container 14 and the radiator 16. The liquid 18 can advantageously be a dielectric liquid. The battery cells of the battery 12 are typically immersed in the liquid.

[0029] In order for the liquid 18 to circulate from the liquid tight container 14 to the radiator 16 and back to the liquid tight container 14, the battery module 10 comprises at least one inflow path 21 for the liquid 18 to flow from the liquid tight container 14 into the radiator 16 and at least one outflow path 22 for the liquid 18 to flow out from the radiator 16 and back into the liquid tight container 14.

[0030] The battery module 10 can further comprise a controller 20. The controller 20 can for example be a Battery Management system (BMS) and can also comprise other control electronics. For example, the controller 20 can be configured to control a flow controller 30 such as a valve or a pump as described below. The flow controller, such as a valve or a pump can be controlled based on some input data such as for example temperature data obtained from a temperature sensor. The temperature sensor can be integrated in the controller 20 and can be configured to sense the temperature of the liquid 18 or some other component of the battery module 10. Other input data such as user control data or time data can also be used to control the flow controller 30.

[0031] The radiator 16 can be thermally isolated from the liquid tight container 14. For example, isolation members 24 can be provided between the liquid tight container 14 and the radiator 16. When the liquid 18 circulated from the liquid tight container 14 and the radiator 16, heat can dissipate from the radiator as indicated by arrows 26 and the liquid can be cooled before returning to the liquid tight container 14, Hereby, the battery 12 can be temperature controlled. In Fig. 2, a detail of a battery module 10 in accordance with another embodiment is depicted. The battery module 10 in the embodiment shown in Fig. 2 is similar to the embodiment shown in Fig.1 . In the embodiment of Fig. 2, a heater 40 is provided inside the liquid tight container 14. The heater 40 can be controlled by the controller 20. The heater 40 can in accordance with some embodiments be activated by the controller 20 a set temperature or temperature span so as to maintain the temperature of the battery at a correct temperature or within a set temperature range. The heater 40 can also in accordance with some embodiments be activated prior to or at battery charging start to have an improved charging temperature for the battery. The heater 40 can in yet other embodiments be activated through a remote interface with a vehicle in which the battery module 10 is installed to prepare the battery module 10 to reach the correct operating temperature prior to battery module 10 usage.

[0032] In Fig. 2, a flow controller 30 is provided. The flow controller 30 can be controlled by the controller 20 to activate / deactivate a liquid flow to the radiator from the liquid tight container based on the temperature of the liquid. The temperature can be obtained via a separate temperature sensor or the controller 20 can have a built-in temperature sensor or the temperature can be obtained in some other way. The flow controller 30 can be activated to start the flow when the battery temperature has reached a first, highest, temperature set for the battery 14 thus starting to cool the liquid 18 in the radiator 16 whereby the battery 14 is cooled through the circulating liquid. The flow controller 30 can be configured to stop the flow when the temperature reaches a second, low, setting of the temperature for the liquid / battery. Hereby the remaining heat is kept inside the battery module 10.

[0033] In accordance with one exemplary embodiment, the flow controller 30 is a valve. In such an embodiment, the flow to the radiator 16 from the liquid tight container 14 can be driven by Buoyancy convection. Buoyancy-driven convection denotes a type of heat transfer in a fluid, in which the fluid flow is driven solely by a density difference due to a temperature gradient in a volume. For example, consider a two-dimensional flow within a square cavity of solid walls, where gravity is present. The left and right boundaries have different temperature values, respectively. The top and bottom boundaries, however, are assumed to be thermally insulated. As the fluid near the left boundary absorbs heat, it becomes less dense and rises due to thermal expansion. The surrounding cooler fluid then moves in to replace it, forming a convection current within the domain. This type of flow is also known as the natural / free convection.

[0034] Using this convection, a flow will be driven by the temperature difference between the radiator 16 and the liquid tight container 14 when the valve is opened.

[0035] In accordance with another exemplary embodiment, the flow controller 30 is a pump. In such an embodiment, the flow to the radiator 16 from the liquid tight container 14 can be driven by the pump.

[0036] In accordance with some embodiments, the radiator 16 of the battery module 10 can comprise enlargements on its outer and / or inner walls. Hereby the surface of the radiator can be increased so as to increase the area for heat dissipation. This can improve the performance of the battery module. For example, fins 44 or similar enlargements can be provided on the outer surface of the radiator 16. Enlargements can also be provided on the inside wall of the radiator 16. For example, inner enlargements such as projections 48 can be formed on the inside wall of the radiator 16.

[0037] The battery module can further comprise flow control plate(s) 27 on one or more of the sides of the battery 12. The flow control plates can be arranged in a bottom to top plane. Hereby the flow is forced in an upwards direction. As a result, more flow (and heat) is forced in an upwards direction whereby more heat is driven to the top side of the liquid tight container 14 so as to increase the convection since the temperature difference between the top side and the bottom side of the liquid tight container will be increased. Also, cooling of the battery cells can be improved by controlling the flow in an upwards direction. Further, a spacer element 23 can be provided at the bottom of the battery 12. The spacer element provides for a space under the battery allowing a more or less free flow of liquid in under the battery 12 such that liquid freely can flow from the bottom side of the liquid tight container 14 up in between individual battery cells of the battery 12.

[0038] In accordance with some embodiments the liquid tight container is filled with a liquid, but for a relatively small volume, such that a small volume about 1 % or even less is unfilled. By not filling the volume completely thermal expansion can be handled. In accordance with some other embodiment, the liquid tight module is completely filled with liquid, in such an embodiment, some kind of expansion device 42 is advantageously provided. The expansion device 42 can be any device allowing for thermal expansion of the liquid. The expansion device can be external to the liquid tight container. In accordance with some embodiments, the expansion device is placed inside the liquid tight container. In such an embodiment, the expansion device can be a compressible member such as a rubber body or a partially gas filled bag or some other member suitable for allowing for thermal expansion / contraction of the liquid inside the liquid tight container 14.

Claims

Claims1 . A battery module (10) comprising:- a battery (12) located immersed inside a liquid tight container (14) and- a radiator (16) located outside the liquid tight container,-a liquid (18) inside the liquid tight container and in the radiator, the battery module (10) comprising at least one inflow path (21 ) for the liquid to flow from the liquid tight container in to the radiator and at least one outflow path (22) for the liquid to flow out from the radiator and back into the liquid tight container, the battery module (10) further comprising a flow controller (30) configured to control the flow to the radiator from the liquid tight container based on a set temperature.

2. The battery module (10) according to claim 1 , wherein the flow to the radiator from the liquid tight container is based on the temperature of the liquid.

3. The battery module (10) according to claim 1 or 2, wherein the flow controller is a valve.

4. The battery module according to claim 1 or 2, wherein the flow controller is a pump.

5. The battery module according to any one of claims 1 - 4, further comprising an insulating layer at least partially covering the outside the liquid tight container.

6. The battery module according to claim 5, wherein the insulating layer comprises an insulating material.

7. The battery module according to claim 5 or 6, wherein the insulating layer comprises a vacuum layer.

8. The battery module according to any one of claims 1 - 7, further comprising a controller (20) configured to control the flow controller.

9. The battery module according to any one of claims 1 - 8, wherein the radiator is thermally insulated from the liquid tight container.

10. The battery module according to any one of claims 1 - 9, wherein the radiator comprises enlargements (44) on at least one outside wall.11 . The battery module according to claim 10, wherein the enlargements comprise fins.

12. The battery module according to any one of claims 1 - 11 , further comprising a heater (40).

13. The battery module according to any one of claims 1 - 12, further comprising a compressible member (42) in the liquid tight container.

14. The battery module according to any one of claims 1 - 13, wherein the radiator comprises enlargements (48) on at least one inside wall.

15. The battery module according to any one of claims 1 - 14, wherein a spacer element (23) is located at the bottom side of the battery such that liquid flow from the bottom side of the battery is facilitated.

16. The battery module according to any one of claims 1 - 15, wherein a flow controller plate (27) is located at at least one side of the battery such that the flow is directed in an upwards direction.

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