Filter-dryer unit for filtering and drying a liquid, 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, comprising a housing (2) that defines a housing volume (3) through which the liquid can flow, a filter element (4) arranged in the housing volume (3) for filtering the liquid, which has a hollow cylindrical filter body (5) that encloses a central axis (6) of the filter element (4) and defines an inner volume (7) of the filter element (4), and a dryer element (8) arranged in the inner volume (7) that includes a desiccant (9) for drying the liquid. A key feature of the invention is that the filter-dryer device (1) has an inner frame (10) arranged radially between the filter body (5) and the dryer element (8), wherein the dryer element (8), the filter body (5), and the inner frame (10) define at least one bypass channel (11) through which the liquid can flow.The invention further relates to an immersion cooling system for an electrically powered vehicle.

Description

[0001] The invention relates to a filter-dryer device for filtering and drying a liquid, comprising a housing that defines a volume through which the liquid can flow, and a filter element arranged within the housing volume and through which the liquid can flow for filtering the liquid. The filter element has a hollow cylindrical filter body that encloses a central axis of the filter element and defines an internal volume through which the liquid can flow. It is further provided that a drying element, containing a desiccant for drying the liquid, is arranged within the internal volume and through which the liquid can flow. The invention relates in particular to an immersion cooling system for an electrically powered vehicle.

[0002] A filter-dryer device of the type mentioned above is described in the publication DE 10 2019 122 034 A1.

[0003] The known filter-dryer device is designed to remove foreign particles and dissolved or free water from a circulating liquid. This water can damage components fluidically integrated into the circuit, for example 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 and a flow-through drying element that binds water carried in the liquid. This process is also referred to as "drying" the liquid by experts in the field.A disadvantage of the known filter-dryer device is that its operation results in an unfavorable overall pressure loss from a fluid mechanics point of view, which is primarily composed of a pressure loss caused by the drying element as well as a pressure loss caused by the filter element.

[0004] 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. In particular, a filter-dryer device with improved fluid-mechanical properties is to be provided. Furthermore, an advantageous immersion cooling system for a vehicle is to be provided.

[0005] In the present invention, this problem is solved by the subject matter of the independent claims. Advantageous embodiments are the subject matter of the dependent claims, the description, and the drawings.

[0006] To solve this problem, the invention proposes that, in a filter-dryer device for filtering and drying a liquid, in particular an oil filter, an inner frame arranged radially between the filter body and the drying element is provided in combination with the features mentioned above. This inner frame supports or carries the filter body, for example radially with respect to the central axis of the filter element. The drying element, the filter body, and the inner frame define at least one bypass channel through which the liquid can flow. Furthermore, a bypass path is provided for guiding the liquid filtered by the filter element. This bypass path leads from the filter body through the at least one bypass channel and through a liquid outlet of the filter element.Furthermore, a dryer path is provided for guiding the liquid filtered by the filter element, leading from the filter body through the dryer element and through the liquid outlet of the filter element.

[0007] This results in the liquid being guided through the internal volume of the filter element via two different paths. The inventors have recognized that the pressure loss occurring via the bypass path is significantly lower than the pressure loss occurring via the dryer path. Overall, the proposed filter-dryer device thus exhibits a favorable total pressure loss, which is low compared to the total pressure loss of known filter-dryer devices. Consequently, the proposed filter-dryer device offers comparatively efficient flow rates.

[0008] The liquid in question can be a coolant, for example oil, or preferably a dielectric coolant, in particular a dielectric liquid mixture. It is understood that other liquids can also be used without departing from the scope of the invention.

[0009] Furthermore, the at least one bypass channel can be helically wound around the central axis. Preferably, two or more helically shaped bypass channels are provided. The at least one helical bypass channel can be arranged concentrically to the central axis. This guides the liquid helically along the central axis through the internal volume of the filter element.

[0010] The at least one bypass channel can be bounded radially on the inside by an outer surface of the dryer element, radially on the outside by an outlet surface of the filter body, and by opposing side surfaces of at least one helically wound strut of the inner frame that rotate around the central axis. Alternatively, the at least one bypass channel can be bounded radially on the inside by an outer surface of the dryer element, radially on the outside by an outlet surface of the filter body, and by opposing side surfaces of two helically wound struts of the inner frame that rotate around the central axis.

[0011] Alternatively, the at least one bypass channel can be formed by a longitudinal channel arranged radially between the inner frame and the filter body and aligned parallel to the central axis. It can also be additionally or alternatively provided that the at least one bypass channel, or a further bypass channel, is formed by a longitudinal channel arranged radially between the inner frame and the drying element and aligned parallel to the central axis. This provides an advantageous embodiment for the at least one bypass channel in which the liquid is guided through the inner volume of the filter element substantially parallel to the central axis.

[0012] Advantageously, the inner frame can be designed as a cross-ribbed frame, comprising at least one ring strut circumferentially around the central axis and at least one longitudinal strut running parallel to the central axis. Alternatively, the inner frame can be designed as a helical frame, comprising at least one ring strut circumferentially around the central axis, several support struts running parallel to the central axis, and at least one strut wound helically around the central axis. These are advantageous embodiments of the inner frame.

[0013] To provide a filter-dryer system with favorable flow characteristics, it can be designed so that the mass or volume flow rate of a first liquid flow, directed along the dryer path during operation, is lower than the mass or volume flow rate of a second liquid flow, directed along the bypass path, due to the flow resistance of the desiccant arranged along the dryer path. The flow resistance of the desiccant arranged along the dryer path is thus such that the mass or volume flow rate of the first liquid flow, directed along the dryer path during operation, is lower than the mass or volume flow rate of the second liquid flow, directed along the bypass path, during operation.This results in a relatively small amount of liquid flowing through the drying element, while a relatively large amount of liquid flows past it. The invention recognizes that this approach achieves a relatively low overall pressure loss and, at the same time, sufficient drying of the liquid.

[0014] Advantageously, the drying element is provided as a desiccant bag containing the desiccant for drying the liquid. The desiccant bag can be loosely inserted into the internal volume of the filter element. The proposed desiccant bag is relatively inexpensive to provide and can be installed relatively easily during the assembly of the filter-dryer unit and / or replaced relatively easily during servicing. Replacing the filter-dryer unit may be necessary, in particular, when the desiccant in the desiccant bag reaches its water absorption capacity, i.e., when it can no longer absorb any more water. Thus, the proposed filter-dryer unit is optimized both economically and in terms of ease of use. The desiccant bag is advantageously designed to be flexible.Furthermore, the dryer bag is advantageously permeable to the liquid in question and impermeable to the desiccant.

[0015] It is further advantageous to provide the desiccant as a powdery, granular, lumpy, or spherical bulk material. This allows it to be incorporated as a bulk material in the dryer element, particularly in the dryer bag. A preferred bulk density of the desiccant is in the range of 700 g / L to 750 g / L, where "g" denotes the weight of the desiccant in grams and "L" denotes the volume of the desiccant in liters.

[0016] It is also advantageous for the desiccant to be provided as a single, continuous, sintered, extruded, or injection-molded desiccant block. The desiccant block can also be contained within a desiccant bag. Such a desiccant block can be easily handled, for example, by hand, which particularly simplifies the installation or replacement of the desiccant element during servicing.

[0017] In an alternative embodiment of the filter-dryer device, in which the desiccant is provided in sintered, extruded or injection-molded form, it is conceivable that the desiccant, due to its production by sintering, extrusion or injection molding, is so dimensionally stable that it can be arranged in the internal volume of the filter element without a separate dryer bag.

[0018] The desiccant in question is water-absorbing, meaning it can permanently absorb, or bind, water. Examples of desiccants include zeolite, silica gel, and silica gel.

[0019] It can further be provided that the filter element has two end discs arranged on opposite end faces of the filter body in the direction of the central axis. It is possible that a first end disc is formed by a non-flowable disc plate, while a second end disc is formed by a flowable disc plate with a flow-through opening. Advantageously, said flow-through opening of the disc plate of the second end disc forms or includes said liquid outlet of the filter element.

[0020] It is also conceivable that the dryer element is arranged concentrically to the central axis. Furthermore, the inner frame can also be arranged concentrically to the central axis. Additionally, the filter body of the filter element can also be arranged concentrically to the central axis. Moreover, it is possible that the housing, or at least one or more of its components, is also arranged concentrically to the central axis. These are advantageous embodiments of the filter-dryer device.

[0021] According to a further fundamental concept of the invention, an immersion cooling system for an electrically powered vehicle is provided. The immersion cooling system comprises 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 are directly surrounded, or can be surrounded, by the liquid, so that during operation of the immersion cooling system, direct heat transfer from the energy storage cells to the liquid, or vice versa, is achieved. Furthermore, the immersion cooling system is equipped with at least one or more filter-dryer units of the type described above, which are fluidically integrated into the cooling circuit, so that the liquid can be efficiently filtered and dried during operation of the immersion cooling system.

[0022] In summary, the present invention preferably relates to a filter-dryer device for filtering and drying a liquid, comprising a housing that defines a housing volume through which the liquid can flow, a filter element arranged in the housing volume for filtering the liquid, which has a hollow cylindrical filter body that encloses a central axis of the filter element and defines an internal volume of the filter element, and a dryer element arranged in the internal volume that includes a desiccant for drying the liquid. A key feature of the invention is that the filter-dryer device has an inner frame arranged radially between the filter body and the dryer element, wherein the dryer element, the filter body, and the inner frame define at least one bypass channel through which the liquid can flow.The invention further relates to an immersion cooling system for an electrically powered vehicle.

[0023] 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.

[0024] It is understood that the features mentioned above and those to be explained below can be used not only in the combination specified, but also in other combinations or on their own, without leaving the scope of the present invention.

[0025] 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.

[0026] They show, schematically, each one Fig. 1 a sectional view of a filter-dryer device for filtering and drying a liquid according to a first embodiment, Fig. 2 in a perspective view a cross-ribbed frame of the filter-dryer unit made of Fig. 1, Fig. 3 a perspective view of a dryer element of the filter-dryer unit Fig. 1, which is designed as a dryer bag, and Fig. 4 A sectional view of a filter-dryer device for filtering and drying a liquid according to a second embodiment.

[0027] The Fig. Figures 1 to 4 show preferred embodiments of a filter-dryer device, collectively designated by reference numeral 1, for filtering and drying a liquid. The filter-dryer device 1 can, for example, be integrated into a cooling circuit (not illustrated) of an immersion cooling system (also not illustrated) for an electrically powered vehicle. The liquid circulating through the cooling circuit, for example, oil or a dielectric coolant, carries foreign particles as well as dissolved or free water during operation. In particular, the entrained water can lead to long-term damage such as corrosion to the components fluidly integrated into the cooling circuit. The filter-dryer device 1 is therefore specifically designed to dry the liquid.

[0028] The filter-dryer unit 1 has a hollow cylindrical housing 2 extending along a housing center axis 34, indicated by a dashed line. The housing 2 defines a housing volume 3 through which the liquid flows in a flow direction 35, indicated by an arrow, from an inlet 36 of the housing 2 to an outlet 37 of the housing 2. The housing 2 is made of two parts and has a cup-shaped upper housing part 2a, symmetrical and coaxial with respect to the housing center axis 34, and a cup-shaped lower housing part 2b, symmetrical and coaxial with respect to the housing center axis 34. The upper housing part 2a has a base 2a1 extending transversely to the housing center axis 34 and a circumferential wall 2a2 projecting perpendicularly from the base 2a1.On the side of the housing top circumferential wall 2a2 facing away from the housing top base 2a1, a circumferential housing top flange 2a3 is provided, extending transversely to the housing center axis 34, which defines an opening 2a4 on the inside of the housing top. The housing bottom 2b has a housing bottom 2b1 extending transversely to the housing center axis 34 and a circumferential housing bottom wall 2b2 projecting perpendicularly from the housing bottom 2b1. On the side of the housing bottom circumferential wall 2b2 facing away from the housing bottom 2b1, a circumferential housing bottom flange 2b3 is provided, extending transversely to the housing center axis 34, which defines an opening 2b4 on the inside of the housing bottom and is complementary to the housing top flange 2a3 of the housing top 2a.

[0029] Furthermore, what is in Fig. As can be seen in Figure 1, the upper housing part 2a and the lower housing part 2b are arranged opposite each other in the direction of the housing center axis 34, wherein the upper housing part flange 2a3 of the upper housing part 2a and the lower housing part flange 2b3 of the lower housing part 2b are arranged tightly against each other, for example by means of a sealant, in particular an O-ring or a sealing cord, so that the housing volume 3 is tightly sealed against the environment 1a of the filter-dryer unit 1. The inlet 36 of the housing 2, which in this case is formed by a hollow cylindrical tube, is positioned centrally on the upper housing part base 2a1 of the upper housing part 2a, is integrally arranged on the upper housing part base 2a1 of the upper housing part 2a and is coaxially aligned with respect to the housing center axis 34.The outlet 37 of the housing 2, which in this case is also formed by a hollow cylindrical tube, is centrally positioned on the housing base 2b1 of the housing lower part 2b, is integrally arranged on the housing base 2b1 of the housing lower part 2b, and is coaxially aligned with respect to the housing center axis 34. The inlet 36 and the outlet 37 point in parallel but opposite directions, so that the filter-dryer unit 1 can be integrated relatively easily into the cooling circuit of the immersion cooling system.

[0030] The filter-dryer unit 1 has a filter element 4 arranged in the housing volume 3 of the housing 2, through which the liquid flows, and which is intended for filtering the liquid. Fig. As can be seen from Figure 1, the filter element 4 has a hollow cylindrical filter body 5, which encloses a central axis 6 of the filter element 4 and defines an internal volume 7 of the filter element 4 through which the liquid can flow. The filter element 4 is supported on the base 2b1 of the lower housing 2b and arranged coaxially in the housing 2, such that the central axis 6 and the housing central axis 34 are identical. The filter body 5 has a frontal surface 39 radially on the outside, which can be loaded with raw liquid, and a rearward surface 16 radially opposite the frontal surface 39 on the inside.The filter body 5 has two axial openings 40, 41 opposite each other in the direction of the central axis 6, wherein the first axial opening 40, located in the region of the inlet 36 of the housing 2, is located on a first end face 29a of the filter element 4 and the second axial opening 41, located in the region of the outlet 37 of the housing 2, is located on a second end face 29b of the filter element 4. Thus, the internal volume 7 is open upwards and downwards in the direction of the central axis 6 through the axial openings 40, 41.

[0031] The filter element 4 further comprises two end discs 27, 28, which are arranged on the aforementioned, opposing end faces 29a, 29b of the filter body 5. The first end disc 27 of the end discs 27, 28, located in the region of the inlet 36 of the housing 2, is formed by a non-flowable disc plate 30 and is tightly connected to the filter body 5. Furthermore, the second end disc 28 of the end discs 27, 28, located in the region of the outlet 37 of the housing 2, is formed by a flowable disc plate 31 with a central flow opening 32 for liquid, arranged concentrically to the central axis 6. This flow opening 32 forms a liquid outlet 14 of the filter element 4.To ensure that liquid flowing into the housing volume 3 through the inlet 36 of the housing 2 is completely filtered during operation of the filter-dryer unit 1, the flow opening 32 of the filter element 4, or the liquid outlet 14 of the filter element 4, is tightly connected to the outlet 37 of the housing 2. This allows liquid to flow along an inlet-filter path 38, indicated by an arrow, from the inlet 36 of the housing 2 exclusively through the filter body 5 to the internal volume 7 of the filter element 4.

[0032] In Fig. Figure 1 further shows that a drying element 8, through which the liquid flows, is arranged in the internal volume 7 of the filter element 4. The drying element 8 is implemented as an elongated drying bag 26, for example a tubular bag, in which a desiccant 9 is contained for drying the liquid, see Figure 1. Fig. 3. The desiccant 9 is provided as a powdery, granular, lumpy, or spherical bulk material. The desiccant bag 26 may be loosely inserted into the inner volume 7 of the filter element 4. The desiccant 9 is water-absorbent, meaning it can permanently absorb, i.e., bind, water.

[0033] The filter-dryer unit 1 is further characterized by an inner frame 10 arranged radially between the filter body 5 and the dryer element 8, which supports or carries the filter body 5, for example radially with respect to the central axis 6 of the filter element. The in Fig. 1 and Fig. The inner frame 10, illustrated in Figure 2, is designed as a helical frame 33 and has a cylindrical grid body 33a, which is constructed from a ring strut 21 rotating circumferentially 17 around the central axis 6, several support struts 21a running parallel to the central axis 6, and two struts 20 each wound helically around the central axis 6. The ring struts 21, the support struts 21a, and the helical struts 20 are connected to one another, for example, integrally. It should also be noted that the filter body 5 is arranged concentrically to the central axis 6. The housing 2 is also arranged concentrically to the central axis 6. Furthermore, the dryer element 8 and the inner frame 10 are arranged concentrically to the central axis 6.

[0034] In order to ensure that the filter-dryer unit 1 has a relatively low overall pressure loss, and thus is favorable for flow from a fluid dynamics perspective, it is further provided that the dryer element 8, the filter body 5 and the inner frame 10 define at least one bypass channel 11 through which the liquid can flow, according to Fig. 1 is wound helically around the central axis 6. The at least one bypass channel 11 is, for example, specifically bounded radially inwards by an outer surface 15 of the dryer element 8, radially outwards by the aforementioned outflow surface 16 of the filter body 5, and by opposing side surfaces 18a, 18b of two helical struts 20 of the inner frame 10 that are adjacent in the circumferential direction 17. This creates a bypass path 12 in the filter-dryer assembly 1 for guiding the liquid filtered by the filter element 4, which leads from the filter body 5, in particular from its outflow surface 16, through the at least one bypass channel 11 and through the liquid outlet 14 of the filter element 4 to the outlet 37.Furthermore, a dryer path 13 is created for guiding the liquid filtered by the filter element 4, which leads from the filter body 5, in particular from its outflow surface 16, through the dryer element 8 and through the liquid outlet 14 of the filter element 4 to the outlet 37. This means that the liquid is guided through the filter-dryer unit 1 via two different paths, whereby the pressure loss occurring via the bypass path 11 is significantly smaller than the pressure loss occurring via the dryer path 13.

[0035] The Fig.Figure 4 shows a sectional view of a filter-dryer device 1 for filtering and drying a liquid according to a second embodiment. In contrast to the previous embodiment, the inner frame 10 is now designed as a cross-ribbed frame 23, which has a cylindrical grid body. This grid body is composed of several ring struts 21 extending circumferentially 17 around the central axis 6 and spaced apart from each other in the direction of the central axis 6, as well as several longitudinal struts 19 running parallel to the central axis 6. The ring struts 21 and the longitudinal struts 19 are connected to each other, for example, integrally. As a result, the at least one bypass channel 11 of the present filter-dryer device 1 is formed by a longitudinal channel 22, which is arranged radially between the inner frame 10 and the filter body 5 and is aligned parallel to the central axis 6. 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, in particular an oil filter, comprising - a housing (2) that limits a housing volume (3) through which the liquid can flow, - a filter element (4) arranged in the housing volume (3) through which the liquid can flow, for filtering the liquid, which has a hollow cylindrical filter body (5) that surrounds a central axis (6) of the filter element (4) and defines an internal volume (7) of the filter element (4) through which the liquid can flow, - a drying element (8) arranged in the internal volume (7) through which the liquid flows, which has a desiccant (9) for drying the liquid, characterized by , that - the filter-dryer unit (1) has an inner frame (10) arranged radially between the filter body (5) and the dryer element (8), which supports the filter body (5), - wherein the dryer element (8), the filter body (5) and the inner frame (10) define at least one bypass channel (11) through which the liquid can flow, - wherein a bypass path (12) leads from the filter body (5) through at least one bypass channel (11) and through a liquid outlet (14) of the filter element (4) to guide the liquid filtered by means of the filter element (4), - wherein a dryer path (13) leads to the flow of the liquid filtered by means of the filter element (4) from the filter body (5) through the dryer element (8) and through the liquid outlet (14) of the filter element (4). [2] Filter-dryer device (1) according to claim 1, characterized by , that - which at least one bypass channel (11) is wound helically around the central axis (6). [3] Filter-dryer device (1) according to claim 2, characterized by , that - which is bounded at least by a bypass channel (11) radially inside by an outer shell surface (15) of the dryer element (8), radially outside by an outflow shell surface (16) of the filter body (5) and in a circumferential direction (17) around the central axis (6) by opposing side surfaces (18a, 18b) of at least one strut (20) of the inner frame (10) wound helically around the central axis (6). [4] Filter-dryer device (1) according to claim 1, characterized by , that - which at least one bypass channel (11) is formed by a longitudinal channel (22) which is arranged radially between the inner frame (10) and the filter body (5) and is aligned parallel to the central axis (6). [5] Filter-dryer device (1) according to claim 1 or claim 4, characterized by , that - which is formed by at least one bypass channel (11) or another bypass channel (11) of a longitudinal channel arranged radially between the inner frame (10) and the dryer element (8) and aligned parallel to the central axis (6). [6] Filter-dryer device (1) according to any one of the preceding claims, characterized by , that - the inner frame (10) is designed as a cross-ribbed frame (23) which has at least one ring strut (21) running around the central axis (6) in a circumferential direction (17) and at least one longitudinal strut (19) running parallel to the central axis (6), or - the inner frame (10) is designed as a helical frame (33) which has at least one ring strut (21) running circumferentially (17) around the central axis (6), several support struts (21a) running parallel to the central axis (6) and at least one strut (20) wound helically around the central axis (6). [7] Filter-dryer device (1) according to any one of the preceding claims, characterized by , that - a mass or volume flow rate of a first liquid flow guided along the dryer path (13) during the operation of the filter-dryer device (1) is smaller than a mass or volume flow rate of a second liquid flow guided along the bypass path (12) during the operation of the filter-dryer device (1) due to a flow resistance of the desiccant (9) arranged along the dryer path (13). [8] Filter-dryer device (1) according to any one of the preceding claims, characterized by , that - the drying element (8) is provided as a dryer bag (26) in which the desiccant (9) is contained for drying the liquid. [9] Filter-dryer device (1) according to any one of the preceding claims, characterized by , that - the desiccant (9) is provided as a powder, granular, lumpy or spherical bulk material. [10] Filter-dryer device (1) according to any one of the preceding claims, characterized by , that - the desiccant (9) is provided as a continuous, sintered, extruded or injection-molded desiccant block. [11] Filter-dryer device (1) according to any one of the preceding claims, characterized by , that - the filter element (4) has two end disks (27, 28) which are arranged on opposite end faces (29a, 29b) of the filter body (5) in the direction of the central axis (6), - wherein a first end disk (27) of the end disks (27, 28) is formed by a non-flowable disk plate (30), - wherein a second end disk (28) of the end disks (27, 28) is formed by a flowable disk plate (31) with a flow opening (32), - wherein the flow opening (32) has or forms the liquid outlet (14) of the filter element (4). [12] Filter-dryer device (1) according to any one of the preceding claims, characterized by , that - the dryer element (8) is arranged concentrically to the central axis (6), and / or - the inner frame (10) is arranged concentrically to the central axis (6), and / or - the filter body (5) is arranged concentrically to the central axis (6), and / or - the housing (2) is arranged concentrically to the central axis (6). [13] 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 9 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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