Filter-dryer unit and immersion cooling system for an electrically powered vehicle

Abstract

The present invention relates to a filter-dryer device (1) for filtering and drying a liquid stream (2), comprising a housing (4) with a housing volume (5). Essentially, a filter element (8) for separating particles from the liquid stream (2), with a first specific flow resistance for the liquid stream (2), and a dryer element (9) for absorbing free water from the liquid stream (2), with a second specific flow resistance for the liquid stream (2), are arranged in the housing volume (5), wherein the filter element (8) and the dryer element (9) are connected in parallel in terms of flow direction.To enable a favorable flow resistance of the filter-dryer unit, it is provided that the second specific flow resistance is greater than or equal to the first specific flow resistance and that the dryer element (9) is smaller than the filter element (8). The invention further relates to an immersion cooling system for an electrically powered vehicle with at least one such filter-dryer unit (1).

Description

[0001] The present invention relates to a filter-dryer device for filtering and drying a liquid stream, comprising a hollow cylindrical housing defining a central axis and enclosing a housing volume through which the liquid stream flows, or can flow, from an inlet of the housing to an outlet of the housing. The invention further relates to an immersion cooling system for an electrically powered vehicle.

[0002] A filter-dryer device of the type mentioned above is described in German patent application DE 10 2019 122 034 A1. It is integrated into a liquid circuit and is designed to separate foreign particles and dissolved or entrained free water from the circulating liquid stream. This free water can damage components integrated into the circuit, particularly through corrosion, or cause electrical short circuits. For this purpose, the known filter-dryer device is equipped with a flow-through filter element for separating foreign particles from the liquid stream and a flow-through dryer element that can permanently bind water entrained in the liquid stream. The removal of water from the liquid stream is referred to as "drying" in the relevant professional circles.A disadvantage of the known filter-dryer system is that it has an unfavorable flow resistance from a fluid mechanics perspective, resulting primarily from the relatively high flow resistance of both the dryer element and the filter element. This unfavorable flow resistance leads to a comparatively high pressure drop between the inlet and outlet of the filter-dryer system, which is undesirable.

[0003] The object of the invention is therefore to provide an improved or at least an alternative embodiment of a filter-dryer device for filtering and drying a liquid stream. In particular, a filter-dryer device with a more favorable flow resistance compared to filter-dryer devices known from the prior art is to be provided. Furthermore, an advantageous immersion cooling system for an electrically powered vehicle is to be provided.

[0004] In the present invention, these problems are solved by the subject matter of the independent claims. Advantageous embodiments are the subject matter of the dependent claims, the description, and the drawings.

[0005] The invention has recognized that the said dryer element of the filter-dryer device has a comparatively high specific flow resistance, whereby, if the dryer element and the filter element are approximately the same size or a comparatively large dryer element is provided, the flow resistance of the filter-dryer device or the resulting pressure loss of the filter-dryer device is largely determined by the dryer element.

[0006] Based on this consideration, to solve the first-mentioned problem in a filter-dryer device for filtering and drying a liquid stream, in combination with the features mentioned above, it is provided that in the housing volume a filter element, radially through which or through which the liquid stream flows, is arranged for separating particles from the liquid stream and has a first specific flow resistance for the liquid stream, and a dryer element, axially supported on the filter element and radially through which or through which the liquid stream flows, is arranged for absorbing free water from the liquid stream and has a second specific flow resistance for the liquid stream, wherein the filter element and the dryer element are connected in parallel in terms of flow technology, so that during operation of the filter-dryer device the liquid stream flows into a first,The liquid flow is divided or divisible into a radial partial flow through the filter element and a second partial flow through the dryer element, wherein the second specific flow resistance is greater than or equal to the first specific flow resistance and wherein the dryer element is smaller than the filter element.

[0007] It is possible for the aforementioned dryer element to not only perform a drying function, but also, as a combined dryer-filter element, to fulfill a filter function—that is, the separation of particles from the liquid stream—due to the intended parallel arrangement of the filter and dryer elements in terms of flow characteristics. The dryer element mentioned at the outset could thus be described as a combined dryer-filter element. To prevent foreign particles from reaching the clean side, the combined dryer-filter element can achieve the same separation efficiency as the filter element.

[0008] The reduction in size of the dryer element results in a comparatively low flow resistance of the filter-dryer unit while simultaneously ensuring sufficient drying of the liquid stream. The aforementioned "flow resistance of the filter-dryer unit" is to be understood as the total flow resistance, which is expediently calculated as the sum of at least one flow resistance of the dryer element, derived from its inflow area exposed to the liquid stream and its second specific flow resistance, and one flow resistance of the filter element, derived from its inflow area exposed to the liquid stream and its first specific flow resistance.Due to the favorable flow resistance of the filter-dryer unit, there is a comparatively low pressure loss between the inlet and outlet of the housing of the filter-dryer unit, thus enabling economical operation of the filter-dryer unit.

[0009] As mentioned at the outset, the liquid stream in question may contain unwanted water, which may be present in the liquid stream as bound water, as free water, or as a mixture of bound and free water. For the purposes of this invention, "bound water" advantageously refers to water that is dissolved in the liquid stream. "Free water," for the purposes of this invention, advantageously refers to water that is undissolved in the liquid stream, i.e., in particular as a separate phase, and more specifically in the form of water droplets.

[0010] The term "specific flow resistance" appropriately refers to the resistance acting on a uniform flow area, for example 1 mm². 2 , flow resistance of a flow-through or flow-through element (i.e., the filter element or the dryer element) that opposes the flow of liquid. As mentioned above, the flow resistance of a flow-through or flow-through element (i.e., the filter element or the dryer element) is conveniently determined from the total inflow area of ​​the element and the specific flow resistance of the element.

[0011] The fluid flow in question can be a cooling fluid, for example oil, or preferably a dielectric fluid, in particular a dielectric fluid mixture. It is understood that other fluids can also be used without departing from the scope of the invention.

[0012] To reduce the size of the dryer element, it can be advantageous to provide that the inflow area of ​​the dryer element exposed to the liquid flow is smaller than the inflow area of ​​the filter element exposed to the liquid flow. It may be advantageous if the ratio of the inflow area of ​​the dryer element to the inflow area of ​​the filter element is in the range between 0.15 and 0.2 or is 0.19. This describes a preferred embodiment of the filter-dryer device in which the dryer element is smaller than the filter element. Within the specified range of the inflow area of ​​the dryer element to the inflow area of ​​the filter element, a preferred, low flow resistance of the filter-dryer device can be achieved.a low pressure drop in the filter-dryer unit is achieved, and on the other hand, sufficient drying capability of the dryer element is ensured, whereby an optimum is given at a ratio of the inflow area of ​​the dryer element to the inflow area of ​​the filter element of 0.19.

[0013] Furthermore, it is conceivable that the axial length of the filter element is greater than the axial length of the dryer element. This results in the dryer element being smaller along its central axis than the filter element, consequently reducing the area of ​​the dryer element exposed to the liquid flow compared to the area of ​​the filter element exposed to the liquid flow. In this case, it may be advantageous for the ratio of the axial length of the dryer element to the axial length of the filter element to be between 0.20 and 0.30, or preferably 0.25. This significantly reduces the flow resistance of the filter-dryer assembly.

[0014] In a further embodiment, it can be provided that, during operation of the filter-dryer device, the mass or volume flow rate of the first liquid partial flow is greater due to the first flow resistance of the filter element than the mass or volume flow rate of the second liquid partial flow due to the second flow resistance of the dryer element. This results in a larger portion of the liquid flow passing through the filter element than a larger portion passing through the dryer element.

[0015] Furthermore, it may be provided that the filter element is designed as a hollow cylinder, coaxially enclosing the central axis and having an inner surface of the filter element that limits a flowable internal volume of the filter element and / or that the dryer element is designed as a hollow cylinder, coaxially enclosing the central axis and having an inner surface of the dryer element that limits a flowable internal volume of the dryer element.

[0016] Furthermore, it may be provided that a dryer bag, through which the liquid flow passes, is arranged in the internal volume of the filter element and / or in the internal volume of the dryer element. This dryer bag contains a water-absorbing material for absorbing dissolved water from the liquid flow. Alternatively, a solid with water-absorbing properties could be provided instead of the filled dryer bag.

[0017] Furthermore, the dryer bag or the aforementioned solid can be loosely inserted into the internal volume of the filter element and / or the internal volume of the dryer element. The dryer bag or the aforementioned solid can be axially supported by at least one end plate of the filter element and / or at least one end plate of the dryer element and / or at least one support element of the dryer element projecting into the internal volume of the dryer element and / or at least one support element of the filter element projecting into the internal volume of the filter element. Furthermore, the dryer bag or the aforementioned solid can be radially supported on the inside of the filter element and / or the inside of the dryer element.

[0018] In a further embodiment, an inner frame of the filter-dryer assembly, designed to radially support the filter element and / or the dryer element, can be arranged within the inner volume of the filter element and / or the dryer element. In this case, the dryer bag or solid can be radially supported against an inner surface of the inner frame.

[0019] In particular, it may be provided that the dryer element has two end disks which are arranged on opposite end faces in the direction of the central axis of a dryer body of the dryer element through which the second partial liquid flow flows or can flow through, and that the dryer element has sealing elements between the end disks and the dryer body, by means of which the end disks and the dryer body are tightly connected to each other.

[0020] The dryer body can have a dryer material that, for example, can be folded so that the body forms a folded star shape. The sealing elements can each be formed by a sealing lip or an O-ring. Furthermore, it is conceivable that the sealing elements and the end plates are designed as integral units, with preferably one sealing element being injection-molded onto an end plate.

[0021] Furthermore, it may be provided that the dryer element, in particular the dryer body of the dryer element, has a water-absorbing material for absorbing free water from the second liquid partial stream, wherein the water-absorbing material is optionally a superabsorber, for example a superabsorber polymer or sodium polyacrylate.

[0022] Furthermore, it may be provided that the water-absorbing material stored in the said dryer bag for absorbing dissolved water from the liquid stream is a superabsorbent, for example a superabsorbent polymer or sodium polyacrylate.

[0023] In an advantageous embodiment, the filter element and the dryer element can be fixed in position relative to the housing volume by axially and / or radially clamping them within the housing. For example, during assembly of the filter-dryer unit, the filter element and the dryer element can be arranged within the housing volume and axially clamped between a housing cup and a housing cover designed to close the housing cup.

[0024] The second problem mentioned at the outset is solved by an immersion cooling system for an electrically powered vehicle, which includes a traction battery with energy storage cells and a cooling circuit in which a liquid circulates. The energy storage cells of the traction battery are fluidically integrated into the cooling circuit and directly surrounded by the liquid, so that during operation of the immersion cooling system, direct heat transfer from the energy storage cells to the liquid is achieved. The immersion cooling system also includes at least one filter-dryer unit as described above, which is fluidically integrated into the cooling circuit, allowing the liquid to be filtered and dried during operation. Due to the comparatively low flow resistance of the filter-dryer unit, the system is highly efficient.Due to the reduced pressure loss of the filter-dryer unit, the proposed immersion cooling system can be operated more economically than before.

[0025] Further important features and advantages of the invention will become apparent from the dependent claims, the drawings and the associated description of the figures based on the drawings.

[0026] It is understood that the features mentioned above and those to be explained below can be used not only in the combinations specified, but also in other combinations or individually, without departing from the scope of the present invention. The components of a higher-level unit, such as a device, apparatus, or arrangement, mentioned above and those to be mentioned below, which are designated separately, can form separate parts or components of this unit or be integral areas or sections of this unit, even if this is depicted differently in the drawings.

[0027] Preferred embodiments of the invention are shown in the drawings and are explained in more detail in the following description, wherein identical reference numerals refer to identical or similar or functionally identical components. Each of these shows, schematically, Fig. 1 in a sectional view a first embodiment of a filter-dryer device according to the invention, Fig. 2 in a sectional view a second embodiment of a filter-dryer device according to the invention.

[0028] The Fig. 1 and Fig. Figure 2 shows a filter-dryer assembly, designated as a whole by reference numeral 1, which is designed for filtering and drying a liquid stream 2. The liquid stream 2, which enters the Fig. 1 and Fig. 2, indicated by arrows, is formed, for example, by a cooling fluid, in particular an oil or a dielectric fluid.

[0029] The filter-dryer unit 1 has a multi-part, hollow cylindrical housing 4 with a central axis 3, a pot-shaped first housing part 32, and a lid-shaped second housing part 33 for closing the first housing part 32. Both components can be made of a single plastic and are monolithic, making the filter-dryer unit 1 relatively lightweight. The first housing part 32 has an inlet 6 designed as a connection point for a line, and the second housing part 33 has an outlet 7, also designed as a connection point for a line, allowing the filter-dryer unit 1 to be easily integrated fluidically into a cooling circuit of an immersion cooling system (not illustrated here). The inlet 6 and / or the outlet 7 of the housing 4 can be arranged coaxially with respect to the central axis 3.The housing 4 internally defines a housing volume 5, through which the fluid flow 2 flows from the inlet 6 of the housing 4 to the outlet 7 of the housing 4.

[0030] In the Fig. 1 and Fig. Figure 2 further shows that a hollow cylindrical filter element 8, through which the liquid stream 2 flows radially, is provided for separating particles from the liquid stream 2, as is a hollow cylindrical dryer element 9, also through which the liquid stream 2 flows radially, for absorbing free water from the liquid stream 2. The filter element 8 and the dryer element 9 are arranged axially one behind the other and axially supported against each other. They are fixed in position within the housing volume 5 of the housing 4 relative to the housing 4 by being axially clamped between the first housing part 32 and the second housing part 33.

[0031] The filter element 8 and the dryer element 9 are connected in parallel in terms of flow direction, such that the liquid flow 2 during operation of the filter-dryer unit 1 is divided, or can be divided, into a first liquid partial flow 10, which flows radially through the filter element 8, and a second liquid partial flow 11, which flows radially through the dryer element 9. Furthermore, the filter element 8 has a first specific flow resistance for the liquid flow 2, and the dryer element 9 has a second specific flow resistance for the liquid flow 2, wherein the second specific flow resistance is greater than or equal to the first specific flow resistance.

[0032] To achieve a favorable flow resistance in the filter-dryer unit 1, the dryer element 9 is designed to be smaller than the filter element 8. Specifically, the inflow area 12 of the dryer element 9, which is exposed to the liquid flow 2, is smaller than the inflow area 13 of the filter element 8, which is exposed to the liquid flow 2. For illustrative purposes, the ratio of the inflow area 12 of the dryer element 9 to the inflow area 13 of the filter element 8 is 0.19, resulting in a favorable flow resistance in the filter-dryer unit 1.

[0033] Furthermore, in the Fig. 1 and Fig. 2. It is evident that the axial length 14 of the filter element 8 is greater than the axial length 15 of the dryer element 9. As a result, the dryer element 9 is smaller along the central axis 3 than the filter element 8, which means that the inflow area 12 of the dryer element 9, accessible to the liquid flow 2, is smaller than the inflow area 13 of the filter element 8, accessible to the liquid flow 2.

[0034] In Fig. 1 and Fig. Figure 2 further shows that the filter element 8 has a hollow cylindrical filter body 26 made of filter material, coaxial with respect to the central axis 3, wherein the filter material is pleated, so that the filter body 26 is arranged as a pleated star. The filter element 8 has two end disks 28, 29 on its axially opposite end faces 27. A first end disk 28 of these end disks 28, 29 is axially supported on the second housing part 33 of the housing 4, and a second end disk 29 of these end disks 28, 29 is axially supported on a first end disk 21 of the dryer element 9. The first end disk 28 of the filter element 8 is preferably free of openings and fluid-tight, so that the liquid flow 2 can only flow through the filter element 8 via the inlet surface 13 of the filter element 8.The second end disk 29 of the filter element 8 has a central opening 30 for the liquid flow 2, which is enclosed by a collar 31 integrally arranged on the second end disk 29. The collar 31 is arranged coaxially with respect to the central axis 3 and projects axially above the second end disk 29.

[0035] As indicated, the dryer element 9 has two end disks 21, 22, which are arranged on opposite end faces 24 of a dryer body 23 of the dryer element 9, through which the second liquid partial stream 11 flows or can flow. The dryer body 23 has a folded or pleated dryer material, such that the body 23 forms a pleated star. Furthermore, the dryer material or dryer body 23 of the dryer element 9 has a water-absorbing substance for absorbing free water from the second liquid partial stream 11, preferably a superabsorbent polymer, for example, a superabsorbent polymer or sodium polyacrylate. Sealing elements 25 are provided between the end disks 21, 22 and the dryer body 23, via which the end disks 21, 22 and the dryer body 23 are tightly connected to each other.The two end disks 21, 22 each have a central opening coaxial to the central axis.

[0036] Furthermore, the dryer element 9 is axially mounted onto the filter element 8, with the first end disk 21 of the dryer element 9 abutting the second end disk 29 of the filter element 8, and the collar 31 of the second end disk 29 of the filter element 8 extending through the central opening of the first end disk 21 of the dryer element 9, so that it projects at least partially into an inner volume 19 of the dryer element 9. This enables the dryer element 9 to be centered with respect to the filter element 8.

[0037] In the Fig. 1 and Fig. Figure 2 further shows that the filter element 8 and the dryer element 9 coaxially enclose the central axis 3, with the filter element 8 having a radially inwardly oriented inner surface 16 and the dryer element 9 having a radially inwardly oriented inner surface 18. The inner surface 16 of the filter element and the inner surface 18 of the dryer element define a flowable internal volume 17 of the filter element 8 and the aforementioned internal volume 19 of the dryer element 9, respectively.

[0038] In the inner volume 17 of the filter element 8 and in the inner volume 19 of the dryer element 9, an inner frame 34 or several inner frames 34 of the filter-dryer unit 1 are arranged, which radially support the filter element 8 and the dryer element 9.

[0039] The in Fig. 2. The illustrated embodiment of the invention differs from the one shown in Fig.In the illustrated embodiment, in particular, a desiccant bag 20 or a water-absorbing solid is arranged in the inner volume 17 of the filter element 8, through which the liquid stream 2 flows, and in which a water-absorbing substance is arranged for absorbing dissolved water from the liquid stream 2. The desiccant bag 20 is loosely inserted into the inner volume 17 of the filter element 8, being radially supported against the inner surface 16 of the filter element. The desiccant bag 20 can contain a water-absorbing substance for absorbing dissolved water from the liquid stream 2, for example, a superabsorbent such as a superabsorbent polymer or sodium polyacrylate. Reference symbol list 1 Filter-dryer unit 2. Fluid flow 3 Center axis 4 cases 5 Case volume 6 Admission 7 Outlet 8 filter elements 9 Dryer element 10 First liquid partial stream 11 Second liquid partial flow 12. Inflow area of ​​the dryer element 13. Inflow area of ​​the filter element 14 Length of the filter element 15 Length of the dryer element 16 Filter element inside 17 Internal volume of the filter element 18 Dryer element inside 19 Internal volume of the dryer element 20 dryer bags 21 First end plate of the dryer element 22 Second end plate of the dryer element 23 dryer bodies 24 end faces of the dryer body 25 sealing elements 26 filter bodies 27 end faces of the filter body 28 First end disc of the filter element 29 Second end disc of the filter element 30 Central Opening 31 collars 32 First housing part 33 Second housing part 34 Inner frame QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2019 122 034 A1

[0002]

Claims

[1] Filter-dryer device (1) for filtering and drying a liquid stream (2), - with a hollow cylindrical housing (4) defining a central axis (3) and limiting a housing volume (5) through which the fluid flow (2) flows or can flow through from an inlet (6) of the housing (4) to an outlet (7) of the housing (4), characterized by , that - in the housing volume (5) a filter element (8) for separating particles from the liquid stream (2) with a first specific flow resistance for the liquid stream (2) and a dryer element (9) for absorbing free water from the liquid stream (2) with a second specific flow resistance for the liquid stream (2), which is axially supported on the filter element (8) and is radially through which the liquid stream (2) or can be flowed through, is arranged in the housing volume (5) axially one after the other. - the filter element (8) and the dryer element (9) are connected in parallel in terms of flow technology, so that the liquid flow (2) during operation of the filter-dryer device (1) is divided or can be divided into a first liquid partial flow (10) flowing radially through the filter element (8) and a second liquid partial flow (11) flowing radially through the dryer element (9), - the second specific flow resistance is greater than or equal to the first specific flow resistance, - the dryer element (9) is smaller than the filter element (8). [2] Filter-dryer device (1) according to claim 1, characterized by , that - a flow area (12) of the dryer element (9) that can be approached by the liquid flow (2) is smaller than a flow area (13) of the filter element (8) that can be approached by the liquid flow (2). [3] Filter-dryer device (1) according to claim 2, characterized by , that - a ratio of the inflow area (12) of the dryer element (9) to the inflow area (13) of the filter element (8) is in a range between 0.15 and 0.2 or is 0.

19. [4] Filter-dryer device (1) according to any one of the preceding claims, characterized by , that - an axial length (14) of the filter element (8) is greater than an axial length (15) of the dryer element (9). [5] Filter-dryer device (1) according to claim 4, characterized by , that - a ratio of one or the axial length (15) of the dryer element (9) to one or the axial length (14) of the filter element (8) is between 0.20 and 0.30 or preferably 0.

25. [6] Filter-dryer device (1) according to any one of the preceding claims, characterized by , that - during the operation of the filter-dryer unit (1) a mass or volume flow of the first liquid partial flow (10) due to the first flow resistance of the filter element (8) is greater than a mass or volume flow of the second liquid partial flow (11) due to the second flow resistance of the dryer element (9). [7] Filter-dryer device (1) according to any one of the preceding claims, characterized by , that - the filter element (8) is designed as a hollow cylinder, coaxially encloses the central axis (3) and has an inner surface (16) of the filter element that limits a flowable inner volume (17) of the filter element (8), and / or - the dryer element (9) is designed as a hollow cylinder, coaxially surrounds the central axis (3) and has a dryer element interior (18) that limits a flowable internal volume (19) of the dryer element (9). [8] Filter-dryer device (1) according to claim 7, characterized in that - a dryer bag (20) arranged in the internal volume (17) of the filter element (8) and / or in the internal volume (19) of the dryer element (9), through which the liquid stream (2) flows, in which a water-absorbing substance is arranged for absorbing dissolved water from the liquid stream (2). [9] Filter-dryer device (1) according to any one of the preceding claims, characterized by , that - the dryer element (9) has two end disks (21, 22) which are arranged on opposite end faces (24) in the direction of the central axis (3) of a dryer body (23) of the dryer element (9) through which or through which the second partial liquid stream (11) flows, - the dryer element (9) has sealing elements (25) between the end discs (21, 22) and the dryer body (23) by means of which the end discs (21, 22) and the dryer body (23) are tightly connected to each other. [10] Filter-dryer device (1) according to any one of the preceding claims, characterized by , that - the dryer element (9) has a water-absorbing material for absorbing free water from the second liquid partial stream (11), - where the water-absorbing material is optionally a superabsorbent, for example a superabsorbent polymer or sodium polyacrylate. [11] Filter-dryer device (1) according to any one of the preceding claims, characterized by , that - the filter element (8) and the dryer element (9) are fixed axially and / or radially clamped in the housing (4). [12] Immersion cooling system for an electrically powered vehicle, - with a traction battery with energy storage cells, - with a cooling circuit in which fluid circulates, - wherein the energy storage cells of the traction battery are fluidically integrated into the cooling circuit and directly surrounded by the liquid, so that in operation of the immersion cooling system a direct heat transfer from the energy storage cells to the liquid is realized, - with at least one filter-dryer device (1) designed according to one of the preceding claims 1 to 11 and fluidically integrated into the cooling circuit, so that liquid can be filtered and dried during operation of the immersion cooling system.

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