Fluid management system and immersion cooled battery system

Abstract

A fluid management system (1) for regulating a coolant (2) in a coolant circuit (3) of an immersion cooled battery system (4) comprises a pump (5), at least one temperature control element (6, 7), at least one filter element (8, 9), a dehumidification element (10) and a housing (11), the pump (5), the at least one temperature control element (6, 7), the at least one filter element (8, 9) and the dehumidification element (10) being arranged in the housing (11), the housing (11) comprises a coolant inlet (12) configured to receive a coolant (2) to be conditioned, a coolant outlet (13) configured to output the conditioned coolant (2), and a coolant path (14) configured to direct the coolant (2) through the housing (11) in a flow direction D from the coolant inlet (12) to the coolant outlet (13).

Description

Technical Field

[0001] The present invention relates to a fluid management system for regulating a coolant in a coolant circuit of an immersion-cooled battery system. The invention also relates to the use of such a fluid management system in a coolant circuit of an immersion-cooled battery system. Background Art

[0002] Today, battery systems, often used in electric vehicles, consist of numerous battery cells arranged in an external housing. Faults in the battery system can sometimes lead to uncontrolled heat generation within the system. Furthermore, regular charging of such battery systems is accompanied by heat generation within the individual battery cells. The faster the charging process proceeds, the more heat is generated. Excessive or even uncontrolled heat generation can cause significant damage to the battery system. To maintain the battery cells within an optimal temperature range, the corresponding battery system is cooled.

[0003] To compete with combustion systems, the automotive industry is striving to shorten the charging time of battery systems. Therefore, improved cooling systems are needed to efficiently dissipate the large amounts of heat generated during the increasingly short charging cycles in battery systems. While battery systems have long been cooled indirectly using cooling plates, through which coolant flows and which are positioned beneath the battery cells, a process known as immersion cooling has recently emerged. In this process, coolant in a coolant circuit is introduced into the battery system's housing and passed through it in such a way that it flows directly around the individual battery cells, immersing them. Due to the direct contact and large contact surface between the coolant and the individual battery cells, heat is removed very efficiently. However, this also places special demands on the coolant's quality to ensure safe operation of the battery system. For example, the coolant temperature and pressure in the coolant circuit must be monitored and adjusted as necessary, and the coolant must be free of dust particles. The coolant's water content is also a key criterion. If the coolant contains too much water, there is a risk of short circuits within the battery system due to the resulting increased electrical conductivity of the coolant. Furthermore, the individual battery cells are exposed to an increased risk of corrosion due to condensed water.

[0004] In the prior art, such as US Pat. No. 11,482,741 B2, it is known to direct coolant circulating in a coolant circuit out of the battery housing for conditioning and to allow it to pass through various treatment elements, such as a cooler, a filter, and / or a water separator, before being reintroduced into the battery housing. In addition to these and other treatment elements, suitable sensors may need to be arranged in the coolant circuit to monitor the condition of the coolant. Consequently, a large number of independent components are required that must be integrated into the coolant circuit to monitor and treat the coolant in order to optimize the operation of the battery system. Summary of the Invention

[0005] An object of the present invention is to provide a system which facilitates conditioning of a coolant in a coolant circuit of an immersion-cooled battery system.

[0006] This problem is solved by a fluid management system according to patent claim 1 and by the use of such a fluid management system according to patent claim 10 .

[0007] Advantageous embodiments and further developments of the invention are subject matter of the dependent claims.

[0008] According to patent claim 1, the present invention is a fluid management system for conditioning a coolant in a coolant circuit of an immersion-cooled battery system, comprising a pump, at least one temperature control element, at least one filter element, a dehumidifying element, and a housing, wherein the pump, the at least one temperature control element, the at least one filter element, and the dehumidifying element are arranged in the housing. The housing includes a coolant inlet configured to receive a coolant to be conditioned, a coolant outlet configured to output the conditioned coolant, and a coolant path configured to guide the coolant through the housing in a flow direction D from the coolant inlet to the coolant outlet.

[0009] In other words, the present invention proposes a fluid management system for conditioning the coolant in the coolant circuit of an immersion-cooled battery system, wherein all the processing elements required for conditioning the coolant are arranged in a compact housing, through which the coolant can be passed by means of a pump also arranged in the housing. For this purpose, the outlet of the battery housing can be connected to the coolant inlet of the housing of the fluid management system, and vice versa. The fluid management system according to the invention thus combines the numerous components and functions required for optimal processing of the coolant in a single, compact housing that can be easily connected to the battery housings of the battery system. The complex operation of inserting numerous individual components into the coolant circuit, which was previously required to ensure optimal fluid quality, can be omitted. The fluid management system according to the invention thus significantly facilitates the processing of such immersion-cooled battery systems.

[0010] One embodiment of the present invention provides several temperature control elements in a housing. In particular, the at least one temperature control element may include a cooling element configured to cool the coolant and a heating element configured to heat the coolant. The fluid management system may also include at least one temperature sensor disposed in the housing and connected upstream of the cooling element and the heating element, the at least one temperature sensor being configured to detect a temperature T of the coolant. The cooling element may be disposed in a first subsection of the coolant path. The heating element may be disposed in a second subsection of the coolant path extending parallel to the first subsection. A third subsection of the coolant path may be disposed parallel to the first subsection and the second subsection and may be configured to bypass the coolant for the cooling element and the heating element. The fluid management system may also include at least one valve disposed in the housing and configured to regulate the coolant flow through the first subsection, the second subsection, and the third subsection based on the coolant temperature T detected by the at least one temperature sensor.

[0011] The temperature of the coolant introduced into the battery housing is crucial for the proper operation of the battery system. Therefore, during coolant conditioning, it is necessary to monitor and, if necessary, adjust the coolant temperature. Generally speaking, as the coolant flows through the battery housing, it absorbs heat energy emitted by the battery cells, causing it to heat up. During the coolant conditioning process, this absorbed heat must be removed from the coolant before it is reintroduced into the battery housing of the battery system. To this end, a cooling element can be provided in the fluid management system housing, through which the coolant passes and through which excess heat energy can be dissipated. Depending on specific conditions, particularly ambient temperature, it may also be necessary to heat the coolant during the conditioning process to bring its temperature back into the temperature range specified for optimal battery system operation. To this end, in addition to the cooling element, the fluid management system can include a heating element arranged in the housing, through which the coolant passes and is thereby heated. The cooling element is arranged in a first subsection of the coolant path, and the heating element is arranged in a second subsection of the coolant path, extending parallel to the first subsection. Temperature sensors connected upstream of the heating element and the cooling element detect the coolant temperature. Furthermore, a valve is provided that regulates the coolant flow through the heating element or the cooling element depending on the detected coolant temperature. Finally, it is also possible that the coolant temperature detected by the temperature sensor is already within a specified temperature range. In this case, the coolant is directed through a third additional subsection of the coolant path, which extends parallel to the first and second subsections of the coolant path and is designed as a bypass, in which the coolant temperature remains constant. For this purpose, a further valve can be provided that releases the flow through the third subsection.

[0012] According to the present invention, the at least one valve may be further configured to allow the coolant to pass through the first section and through the cooling element in response to the detected coolant temperature T being greater than 35°C, and to allow the coolant to pass through the second section and through the heating element in response to the detected coolant temperature T being less than -5°C. The at least one valve may be further configured to allow the coolant to pass through the third section and bypass the cooling element and the heating element in response to the detected coolant temperature T being greater than -5°C and less than 35°C.

[0013] According to a further embodiment of the present invention, the at least one filter element may comprise a pre-filter and a main filter, which are configured to remove dust particles from the coolant. The pre-filter may be connected upstream of the pump and the main filter may be connected downstream of the at least one temperature control element. The pre-filter may be a simple sieve, which protects the pump, for example, by removing coarser dust particles from the coolant. The main filter may be designed in such a way that smaller dust particles can also be reliably removed from the coolant before the coolant is reintroduced into the battery housing.

[0014] The fluid management system according to the present invention may further include an expansion tank disposed within the housing and configured to receive coolant received by the coolant inlet. The volume of coolant circulating in the coolant circuit may vary depending on its temperature. The volume of the expansion tank, which may be disposed immediately after the coolant inlet of the housing, may be sized to accommodate varying coolant volumes without causing excessive pressure increases or decreases in the coolant circuit.

[0015] To this end, the fluid management system may further include a ventilation element configured to provide pressure compensation to the expansion tank. The ventilation element and a dehumidifying element may be arranged on the expansion tank. The dehumidifying element may be configured to remove moisture from air flowing in from the outside through the ventilation element. The ventilation element may, for example, be designed as a vent cap and include a valve-controlled opening through which ambient air can enter the expansion tank or air can escape from the expansion tank to the outside. At the same time, the dehumidifying element ensures that no additional moisture is introduced into the coolant via the ambient air flowing in from the outside, which would increase the conductivity of the coolant in an undesirable manner.

[0016] According to one embodiment, the ventilation element and the dehumidification element may be detachably connected to each other to form one unit.

[0017] It may also be provided that the fluid management system may further comprise a conductivity sensor, which is arranged in the housing and is configured to measure the conductivity of the coolant. In particular, an output signal from the conductivity sensor may be used to control the dehumidifying element.

[0018] In an embodiment, the fluid management system may further include a pressure relief valve disposed between the coolant circuit and the expansion tank and configured to discharge the coolant into the expansion tank to reduce pressure.

[0019] Finally, the present invention also relates to an immersion-cooled battery system, comprising a fluid management system according to any one of claims 1 to 9, a coolant circuit in which the fluid management system is arranged, and a battery housing in which battery cells are arranged. The coolant flows around the battery cells, and the battery housing comprises an outlet connected to a coolant inlet of the housing of the fluid management system, and an inlet connected to the coolant outlet of the housing of the fluid management system. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In the following, the invention is explained in more detail with reference to embodiments examples shown in the accompanying drawings.

[0021] Figure 1 is a schematic representation of an example of an embodiment of a fluid management system according to the present invention. DETAILED DESCRIPTION

[0022] Figure 1 A schematic diagram of an embodiment example of a fluid management system 1 according to the present invention is shown. The fluid management system 1 is used to condition a coolant 2 that circulates in a coolant circuit 3 of an immersion-cooled battery system 4. The immersion-cooled battery system 4 comprises a battery housing 24 in which battery cells are arranged. Figure 1 The battery cells are cooled by immersion. To this end, coolant 2 is introduced into the battery housing 24 via inlet 26 in such a way that the battery cells are completely immersed in coolant 2 and are directly surrounded by it. The coolant 2 can then leave the battery housing 24 again via outlet 25.

[0023] In order to protect the battery cells and maintain their full functionality, the coolant 2 must meet strict requirements, especially regarding its temperature T, pressure, and water content. For this reason, a fluid management system 1 is integrated into the coolant circuit 3 for the continuous regulation of the coolant 2. The fluid management system 1 is designed as a compact module in which all the processing elements required for regulating the coolant 2 (which will be explained in more detail below) are arranged within a common outer housing 11. The housing 11 is connected to the battery housing 24 in that the outlet 25 of the battery housing 24 is connected to the coolant inlet 12 of the housing 11, and the inlet 26 of the battery housing 24 is connected to the coolant outlet 13 of the housing 11. In this way, the coolant 2 to be regulated can be fed into the housing 11 through the coolant inlet 12, while the regulated coolant 2 can be fed back from the housing 11 through the coolant outlet 13 and into the battery housing 24.

[0024] Between the coolant inlet 12 and the coolant outlet 13, the coolant 2 is guided through the housing 11 along the coolant path 14 in the flow direction D by means of a pump 5.

[0025] Several elements for regulating the coolant 2 are arranged inside the housing 11. A cooling element 6 and a heating element 7 are integrated into the coolant circuit 3 to adjust the temperature T of the coolant 2. The cooling element 6 is arranged in a first partial section 16 of the coolant path 14, while the heating element 7 is arranged in a second partial section 17 of the coolant path 14. The two partial sections 16 and 17 of the coolant path 14 extend parallel to each other. A further third partial section 18 of the coolant path 14 also extends parallel to the two partial sections 16 and 17 and is designed as a bypass. A temperature sensor 15 is connected upstream of the temperature control elements 6, 7, and in Figure 1 the exemplary embodiment shown, the temperature sensor 15 is integrated into the valve 19, although in principle it can also be designed independently of the valve 19. Depending on the temperature T of the coolant 2 detected by the temperature sensor 15, the valve 19 and a further valve 20 regulate the flow rate of the coolant 2 through the three parallel partial sections 16, 17, 18. In the exemplary embodiment shown, if the temperature sensor 15 detects that the temperature T of the coolant 2 > 35 °C, the coolant 2 passes through the first partial section 16 and through the cooling element 6. The coolant 2 is cooled by the cooling element 6 until its temperature returns to a predetermined setpoint range. If the temperature sensor 15 detects that the temperature T of the coolant 2 < -5 °C, the coolant 2 passes through the second partial section 17 and through the heating element 7. In this case, the coolant 2 is heated by the heating element 7 until its temperature returns to a predetermined setpoint range. If the temperature sensor 15 detects the temperature T of the coolant 2 for which the following condition applies: -5 °C < T < 35 °C, the coolant 2 passes through the third partial section 18 of the coolant path 14, which is designed as a bypass and the temperature of the coolant 2 is not affected.

[0026] Two filter elements 8 and 9 are arranged in a housing 11 to remove dust particles from the coolant 2. The pre-filter 8 is arranged upstream of the pump 5 in the flow direction D and is used to remove coarse dust particles from the coolant 2 to protect the pump 5. The pre-filter 8 is designed as a simple sieve. The main filter 9 is arranged downstream of the temperature control elements 6 and 7 in the flow direction D and is designed to also filter out smaller dust particles from the coolant 2 to protect the battery cells.

[0027] Immediately after the coolant inlet 12, an expansion tank 21 is arranged in the housing 11, which is used to receive the coolant 2. The volume of the expansion tank 21 is determined in such a way that temperature-related changes in the volume of the coolant 2 can be accommodated without causing an excessive increase or decrease in the pressure in the coolant circuit 3. Figure 1 In the illustration of FIG, a specific coolant level 27 is indicated. The expansion tank 21 is filled with air above the surface of the coolant 2. If the coolant 2 expands due to the temperature, this air-filled volume can usually receive the coolant 2.

[0028] A ventilation element 22 for pressure compensation and a dehumidifying element 10 are arranged on the expansion tank 21. The ventilation element 22 is designed as a vent cap mounted on the expansion tank 21 and includes a valve-controlled opening through which ambient air can enter the expansion tank 21 or air can escape from the expansion tank 21 to the outside. Air entering the expansion tank 21 from the outside introduces moisture into the coolant circuit 3, which can undesirably increase the conductivity of the coolant 2. For this purpose, the dehumidifying element 10 is arranged in the expansion tank 21. For example, it can be designed as an air dryer that removes moisture directly from the air flowing in from the outside through the ventilation element 22.

[0029] The ventilation element 22 and the dehumidifying element 10 can be detachably connected to each other to form a unit. This allows the supplied ambient air to be dehumidified in a particularly efficient manner.

[0030] A level sensor 28 and a drain plug 29 for controlled draining of the coolant 2 may also be arranged in the expansion tank 21 .

[0031] Furthermore, a conductivity sensor 23 and a pressure and temperature sensor 30 are integrated into the coolant circuit 3. Sensors 23 and 30 are connected downstream of the temperature control elements 6, 7 and the filter elements 8, 9 and protect the battery cells by additionally monitoring the temperature, pressure, and conductivity of the conditioned coolant 2 before it is fed back into the battery housing 24. Finally, a pressure relief valve 31 is provided, via which the coolant 2 can be discharged into the expansion tank 21 for pressure reduction purposes.

[0032] Reference Signs List

[0033] Fluid Management System 1

[0034] Refrigerant 2

[0035] Coolant circuit 3

[0036] Immersion cooled battery system 4

[0037] Pump 5

[0038] Temperature control element / cooling element 6

[0039] Temperature control element / heating element 7

[0040] Filter element / prefilter8

[0041] Filter element / main filter 9

[0042] Dehumidification element 10

[0043] Housing 11

[0044] Coolant inlet 12

[0045] Coolant outlet 13

[0046] Coolant path 14

[0047] Temperature sensor 15

[0048] Part 1 Section 16

[0049] Part 2 Section 17

[0050] Part III Section 18

[0051] Valve 19

[0052] Valve 20

[0053] Expansion tank 21

[0054] Ventilation element 22

[0055] Conductivity sensor 23

[0056] Battery housing 24

[0057] Exit 25

[0058] Entrance 26

[0059] Coolant level 27

[0060] Liquid level sensor 28

[0061] Drain plug 29

[0062] Pressure and temperature sensor 30

[0063] Pressure relief valve 31

Claims

1. A fluid management system (1) for regulating a coolant (2) in a coolant circuit (3) of an immersion-cooled battery system (4), the fluid management system (1) comprising: Pump (5); at least one temperature control element (6, 7); at least one filter element (8, 9); Dehumidification element (10); and A housing (11) is provided in which the pump (5), the at least one temperature control element (6, 7), the at least one filter element (8, 9) and the dehumidifying element (10) are arranged, the housing (11) comprising a coolant inlet (12) configured to receive a coolant (2) to be conditioned, a coolant outlet (13) configured to output the conditioned coolant (2) and a coolant path (14) configured to guide the coolant (2) along a flow direction D from the coolant inlet (12) through the housing (11) to the coolant outlet (13).

2. The fluid management system (1) according to claim 1, wherein: The at least one temperature control element (6, 7) comprises a cooling element (6) configured to cool the coolant (2), and a heating element (7) configured to heat the coolant (2), The fluid management system (1) further comprises at least one temperature sensor (15) arranged in the housing (11) and connected upstream of the cooling element (6) and the heating element (7), the at least one temperature sensor (15) being configured to detect a temperature T of the coolant (2). The cooling element (6) is arranged in a first subsection (16) of the coolant path (14), The heating element (7) is arranged in a second subsection (17) of the coolant path (14) extending parallel to the first subsection (16), A third subsection (18) of the coolant path (14) is arranged parallel to the first subsection (16) and the second subsection (17) and is configured as a bypass for the coolant (2) for the cooling element (6) and the heating element (7), and The fluid management system (1) further comprises at least one valve (19, 20) which is arranged in the housing (11) and is configured to regulate the flow of the coolant (2) through the first sub-section (16), the second sub-section (17) and the third sub-section (18) according to the temperature T of the coolant (2) detected by the at least one temperature sensor (15).

3. The fluid management system (1) according to claim 2, wherein: The at least one valve (19, 20) is further configured to: In response to the detected temperature T of the coolant (2) being greater than 35° C., allowing the coolant (2) to pass through the first section (16) and through the cooling element (6); In response to the detected temperature T of the coolant (2) being less than -5°C, allowing the coolant (2) to pass through the second partial section (17) and through the heating element (7); and In response to the detected coolant (2) temperature T being greater than -5°C and less than 35°C, the coolant (2) is allowed to pass through the third section (18) and bypass the cooling element (6) and the heating element (7).

4. The fluid management system (1) according to any one of claims 1 to 3, wherein: The at least one filter element (8, 9) comprises a pre-filter (8) and a main filter (9), the pre-filter (8) and the main filter (9) being configured to remove dust particles from the coolant (2), The pre-filter (8) is connected upstream of the pump (5), and The main filter (9) is connected downstream of the at least one temperature control element (6, 7).

5. The fluid management system (1) according to any one of claims 1 to 4, wherein: The fluid management system (1) further includes an expansion tank (21) disposed in the housing (11) and configured to receive the coolant (2) received by the coolant inlet (12).

6. The fluid management system (1) according to claim 5, wherein: The fluid management system (1) further comprises a venting element (22) configured to provide pressure compensation to the expansion tank (21), The ventilation element (22) and the dehumidification element (10) are arranged on the expansion tank (21), and The dehumidifying element (10) is configured to remove moisture from air flowing in from the outside through the ventilation element (22).

7. The fluid management system (1) according to claim 6, wherein: The ventilation element (22) and the dehumidification element (10) are detachably connected to each other to form a unit.

8. The fluid management system (1) according to any one of claims 1 to 7, wherein: The fluid management system (1) further includes a conductivity sensor (23) disposed in the housing (11) and configured to measure the conductivity of the coolant (2).

9. The fluid management system (1) according to any one of claims 1 to 8, wherein: The fluid management system (1) further includes a pressure relief valve (31) disposed between the coolant circuit (3) and the expansion tank (21) and configured to discharge the coolant (2) into the expansion tank (21) for decompression.

10. An immersion-cooled battery system (4), comprising: The fluid management system (1) according to any one of claims 1 to 9; a coolant circuit (3) in which the fluid management system (1) is arranged; and A battery housing (24) in which battery cells are arranged, around which the coolant (2) flows, and comprising an outlet (25) connected to a coolant inlet (12) of the housing (11) of the fluid management system (1), and an inlet (26) connected to a coolant outlet (13) of the housing (11) of the fluid management system (1).

Images