Liquid filters and use

Abstract

Liquid filter (1), in particular oil filter, for filtering a liquid, in particular an oil, which has a raw-side inlet surface and a clean-side outlet surface which are connected to each other by means of a flow path, and a filter body which has a filter medium folded to form a bellows (2) with a plurality of folds (3) which extends between two edge folds, wherein each fold (3) has a first fold leaf and a second fold leaf which adjoin each other at a fold edge, a fold edge height and two opposing fold end faces (22, 23), and wherein the liquid filter (1) is configured to be installed in a space which defines a space volume by means of a base freeform surface (12), a ceiling freeform surface (8) and a side freeform surface (13), wherein the bellows (2) is formed in one piece and at least two of the plurality of folds (3) have a different height,wherein the fold edge heights are adapted to an uneven or inclined contour of the top freeform surface (8) and / or the base freeform surface (12), and wherein the fold end faces (22, 23, 24) of at least two folds (3) are adapted to a contour of the side freeform surface (13) facing them, wherein the shape of an envelope of all fold end faces (22, 23, 24) and the edge folds deviates from a rectangle, wherein the bellows (2) is formed entirely from a single material, wherein the bellows (2) is not attached to the housing by means of overmolding, wherein the bellows (2) is inserted into a housing pot (101) with a side wall and a bottom surface, wherein the shape of the side wall corresponds to the shape of the side freeform surface (13), and wherein the shape of the bottom surface corresponds to the shape of the base freeform surface (12),wherein at least one fold (3) on the raw-side inflow surface and / or on the clean-side outflow surface and / or at least one fold end face (22, 23, 24) is attached to the side wall by clamping, pressing, gluing or welding, characterized in that , the bellows (2) has at least two bellows sections (4, 5, 6) with different fold edge heights, which are arranged to leave a predetermined distance from the ceiling freeform surface section (9, 10, 11) and / or the housing cover (102) in at least two ceiling freeform surface sections (9, 10, 11) of the ceiling freeform surface (8). and / or the bellows (2) has at least two bellows sections (4, 5, 6) with different fold edge heights, which are arranged to leave a predetermined distance from the basic freeform surface section or the housing pot bottom surface in at least two basic freeform surface sections of the basic freeform surface (12).

Description

Technical field

[0001] The invention relates to a liquid filter, in particular an oil filter, for filtering a liquid, in particular an oil, which has a raw-side inflow surface and a clean-side outflow surface which are connected to each other by means of a flow path, and to a filter body which has a filter medium folded to form a bellows with a plurality of folds, wherein each fold has a fold edge height and two opposite fold end faces, and wherein the bellows is arranged to be installed in a space which defines a space volume by means of a base freeform surface, a ceiling freeform surface and a side freeform surface. State of the art

[0002] A liquid filter is disclosed in DE 10 2016 007 113 A1. A filter element disclosed therein has a pleated filter medium body on which an at least partially circumferential, protruding separating edge is arranged, which is formed integrally with the filter medium body, wherein the distance between the separating edge and the upstream or downstream side of the filter medium body is variable.

[0003] WO 2011 / 026 999 A1 relates to a filter for filtering fluids with a filter element having a zigzag-folded filter medium. On a raw side and / or on a clean side, a plurality of elongated adhesive sections are arranged along at least two adhesive tracks on the filter medium, which run at least partially obliquely or perpendicularly to the fold edges.

[0004] From DE 10 2018 209 671 A1, a filter device is known, comprising a filter housing and a pleated filter medium with pleats of a pleat height and a pleat spacing, wherein the filter housing has an interior space with a room height and the filter medium is arranged in the interior space. The interior space has a variable room height, wherein the pleat height is adapted to the room height.

[0005] DE 10 2014 016 908 A1 shows a filter element for fluids with a filter bellows, wherein at least one section of one of the end edges runs obliquely to at least one of the fold edges such that in this section the fold edges on one surface have a different length than the fold edges of the other surface and wherein the folds are sealed laterally on the side of the end edges.

[0006] DE 10 2008 058 356 A1 discloses a filter element comprising a bellows with adjacent upper fold backs and adjacent lower fold backs, wherein the lower fold backs lie in a base plane and wherein the upper fold backs project from the base plane with fold heights, characterized by at least two different fold heights of the upper fold backs.

[0007] From DE 10 2012 000 490 A1, an air filter element is known with an inlet surface, an outlet surface and a filter medium, wherein the filter medium extends between the inlet surface and the outlet surface, wherein at least one of the inlet surface and the outlet surface has a back offset at least sectionally, wherein a functional component to be brought into operative relationship with the air filter element can project at least partially into a free space resulting from the back offset.

[0008] DE 10 2013 008 391 A1 discloses a filter medium, in particular an air filter medium, comprising a first filter layer and a second filter layer. The first filter layer has a first filter layer section and a second filter layer section, which is arranged downstream of the first filter layer section in the direction of flow through the filter medium. The first filter layer section has a first packing density of fibers, and the second filter layer section has a second packing density of fibers that differs from the first packing density.

[0009] Such liquid filters are known. These are liquid filters used for filtering liquids. The liquid could be, for example, oil or fuel. The liquid filter is installed in a filter assembly that can be used, for example, in internal combustion engines.

[0010] For filtration purposes, the liquid to be filtered (raw liquid) is directed via the flow path to the raw-side inlet surface of the liquid filter. The filter body is located downstream of this inlet surface in the direction of flow. It consists of a bellows containing the filter medium, which is folded to form numerous pleats over which the liquid to be filtered is guided. Each pleat of the bellows has a fold edge height and two fold faces, each oriented perpendicular to the flow direction of the liquid. After filtration, the liquid (clean liquid) exits the liquid filter at the clean-side outlet surface. It can then be used for its intended purpose.

[0011] Such a liquid filter is installed in a housing through which the liquid to be filtered (raw liquid) flows. This housing is typically adapted to the external requirements of the structural components in which it is located. These components could, for example, be an internal combustion engine. Depending on the structural requirements of such housings, their shape will vary considerably. It will generally deviate from simple geometric forms such as cuboids or similar shapes. Such a housing is therefore bounded or defined by a base freeform surface, a ceiling freeform surface, and side freeform surfaces. These surfaces can differ from simple basic geometric shapes such as rectangles, triangles, or similar forms.The bellows are positioned on the base freeform surface so that the fold edges extend from the base freeform surface towards the ceiling freeform surface. The fold edge height is then the height of the fold edges above the base freeform surface. Furthermore, the fold ends run parallel to an extension of the side freeform surface from the base freeform surface towards the ceiling freeform surface.

[0012] The bellows of the filter body has a bellows base. This bellows base is positioned on the base freeform surface. It is known to design the bellows base to be rectangular. The dimensions of this rectangular shape are then adapted to the base freeform surface so that the bellows, in its rectangular form, fits onto the base freeform surface. The same applies to the fold edge heights. These are all adjusted so that they have an identical fold edge height above the bellows base, corresponding at most to the smallest distance between the top freeform surface and the base freeform surface within the installation space. In this way, the bellows or the liquid filter can be accommodated within the installation space volume.

[0013] In this liquid filter arrangement, however, certain sections of the installation space remain unused if the installation area deviates from a simple geometric shape, such as a cuboid, as no filter medium is placed within them. This results in irregularly shaped liquid filters within the given installation space. These filters make poor use of the available space and therefore provide only a low filtration performance. Disclosure of the invention

[0014] The invention therefore aims to provide a liquid filter that optimally utilizes the available installation space and thus provides high filtration performance. It also seeks to achieve cost-effective manufacturing with as few components as possible. Furthermore, an advantageous application must be specified.

[0015] This problem is solved by a liquid filter having the features of claim 1. Further developments of the invention are specified in the dependent claims.

[0016] The liquid filter according to the invention comprises a bellows made of pleated filter medium with a plurality of pleats. Each pleat has a first and a second pleat leaf, which abut each other at a pleat edge. Adjacent pleats of the bellows also abut each other at a pleat edge with their side edges. The first pleat leaves of adjacent pleats lie substantially parallel to each other. The pleat leaves extend between an inlet surface and an outlet surface. The end faces of the pleats run substantially perpendicular to the inlet and outlet surfaces. Within a pleat, the pleat height is constant, i.e., the pleat height of the bellows can change in the pleat direction, but not in the direction along the pleat edges.In the liquid filter according to the invention, the bellows is formed in one piece, and at least two fold edge heights of the plurality of folds are adapted to the contour of the ceiling freeform surface or the base freeform surface. The contour of the ceiling freeform surface is intuitively defined as the path of a connecting line between a plurality of selected points on the ceiling freeform surface, depending on the perpendicular distance of corresponding points on the base freeform surface. The same applies to the base freeform surface. The base freeform surface and / or the ceiling freeform surface is inclined or uneven, i.e., it has at least one inclination, curvature, and / or step. If one of the two surfaces mentioned is flat and the other is not, the distance between these two surfaces varies.

[0017] The fold edge height of the bellows is therefore variable within the bellows itself. Different fold edge heights can be present within a single-piece bellows. This allows the fold edge height to be flexibly adapted to the available installation space. The fold edge height is adjusted to the height of the installation space (the vertical distance between a point on the base freeform surface and a point on the top freeform surface). This ensures that the available installation space is optimally covered by adjusting the fold edge height to the installation space height. Improved filtration performance can be achieved, particularly through the ability to reduce pressure loss by using a larger filter area. At the same time, the separation efficiency can be increased.Even with the same pressure drop, a higher separation efficiency can be achieved compared to a conventional liquid filter by using a filter medium with a higher separation capacity. The larger filter surface also offers the possibility of extending the service life or maintenance interval of the liquid filter. Furthermore, components and attachments can be better integrated by adjusting the fold edge heights to the specific conditions of the freeform ceiling or base surface.

[0018] According to the invention, the bellows has at least two bellows sections with different fold edge heights, which are arranged to leave a predetermined distance from the ceiling freeform surface section in at least two ceiling freeform surface sections.

[0019] The ceiling freeform surface can be composed of two or more different ceiling freeform surface sections. These different ceiling freeform surface sections can each have a different height above the base freeform surface. The bellows of the liquid filter accommodates these conditions of the installation space by forming bellows sections corresponding to the ceiling freeform surface sections. The fold edge height in each bellows section is individually adapted to the available installation space height. This is achieved by leaving a predetermined gap in each bellows section between the respective fold edges and the ceiling freeform surface.The distance between the fold edges and the freeform ceiling surface follows the shape of the freeform ceiling surface; this distance can be constant or vary according to the characteristics of the freeform ceiling surface, even within a section of the surface. The distance can be varied depending on requirements, such as the integration of components or add-ons. The available installation space is optimally utilized. If the filter element is installed in a housing with a downstream cover, the cover preferably replicates the shape of the freeform ceiling surface. Alternatively, the cover can follow the contour of the downstream surface.

[0020] It is preferred that the distance between two adjacent first fold edges in a bellows transition section between the two bellows sections is different from the distance between two adjacent second fold edges in a bellows section.

[0021] Therefore, not only is the fold edge height adapted to the available installation space, but the folding of the filter medium is also varied according to the conditions of the installation space. This allows edges, steps, or similar features present in the basic freeform surface to be optimally covered by the filter medium. The folds can easily "bridge" such edges or steps by varying the distance between the individual fold edges.

[0022] Alternatively or additionally, in the liquid filter according to the invention, at least two fold end faces are adapted to the contour of the freeform surface facing them. The freeform surface deviates from a standard rectangular shape and may optionally have at least one curved section. The contour of the freeform surface is intuitively defined as the line connecting a plurality of selected points on a first freeform surface, relative to the perpendicular distance of corresponding points on the opposite freeform surface.

[0023] This allows the contour of the bellows' perimeter to be adapted to the contour of the freeform surface. The fold ends follow the contour of the freeform surface along its entire length, even if the freeform surface is curved, i.e., has a curved section. This results in a variable fold length. The contour of the envelope of all end faces on one side can differ from the contour of the envelope of all end faces on the other side. Thus, the bellows base surface replicates the freeform surface. The freeform surface is optimally utilized and (almost) completely covered by the filter medium. The bellows base surface deviates from the conventional rectangular shape and can be flexibly adapted to the existing freeform surface.Improved filtration performance can be achieved, particularly by reducing pressure drop through a larger filter area. Simultaneously, the separation efficiency can be increased. Thus, even with the same pressure drop, compared to a conventional liquid filter, the use of a higher-efficiency filter medium can lead to increased separation efficiency. The larger filter area also allows for extending the service life or maintenance interval of the liquid filter. Furthermore, components and attachments can be better integrated by tailoring the bellows base area to the specific characteristics of the freeform surface.

[0024] It is advantageous that, in addition, the at least two fold edge heights of the multitude of folds are adapted to the contour of the ceiling freeform surface. The contour of the ceiling freeform surface is intuitively defined as the line connecting a plurality of selected points on the ceiling freeform surface, depending on the perpendicular distance of corresponding points on the base freeform surface. The fold edge height of the bellows is therefore also variable within the bellows. Different fold edge heights can be present in a single-piece bellows. This allows the fold edge height to be flexibly adapted to the available installation space. The fold edge height is adjusted to the height of the installation space (the perpendicular distance between a point on the base freeform surface and a point on the ceiling freeform surface).This ensures optimal coverage of the available installation space, particularly in terms of height, by adjusting the folding edge height to match the installation space height. Improved filter performance can be achieved, especially through the ability to further reduce pressure loss with a larger filter area. Simultaneously, the separation efficiency can be increased. This can be achieved, even with the same pressure loss, compared to a conventional liquid filter, by using a filter medium with a higher separation capacity. The larger filter area also allows for an extension of the liquid filter's service life or service interval. Furthermore, by adjusting the folding edge heights to the specific characteristics of the freeform ceiling surface, components and attachments can be integrated more effectively.

[0025] According to the invention, the bellows is incorporated into a housing pot with a side wall and a bottom surface. To optimally utilize the installation space, the shape of the side wall corresponds to the shape of the side freeform surface, and the shape of the bottom surface corresponds to the shape of the base freeform surface. The housing pot can remain open or be closed with a housing cover. The shape of the housing cover is preferably adapted to the shape of the top freeform surface. It is advantageous if the housing cover covers as little of the inlet area as possible. For this purpose, the cover can have a multitude of openings, for example, designed as a grid. The cover can be detachably or permanently connected to the housing pot. The bellows can be connected to the housing pot at its edges and end faces. A section of the edge folds can be pressed between the housing pot and the cover.

[0026] According to the invention, at least one fold on the raw-side inflow surface and / or on the clean-side outflow surface and / or at least one fold end face is attached to the side wall of the filter pot by clamping, pressing, gluing or welding.

[0027] According to the invention, in a one-piece bellows design, the bellows is not attached to the housing by overmolding. The filter element can be assembled or fitted, for example, by means of glued-on side strips. The flexible filter element can then be assembled and installed in the housing by means of a joining process (e.g., gluing, welding, etc.). Once the bellows is firmly attached to the filter housing, a housing cover is unnecessary.

[0028] According to the invention, the bellows is formed entirely from a single material. Manufacturing such a one-piece bellows is cost-effective and efficient.

[0029] The one-piece filter bellows is preferably made of a so-called depth filtration filter medium. Suitable filter media of this type are preferably wet- or dry-laid random fiber fabrics that are mechanically and / or chemically bonded. Such a random fiber fabric has voids between the fibers. The filter medium can contain natural fibers and at least a proportion of synthetic fibers, for example, polyethylene terephthalate (PET) and / or glass fibers; this proportion can be selected to suit the specific filtration application. For example, the proportion can be greater than 10% by weight. The filter medium can also consist of synthetic fibers and / or glass fibers, whereby, in the case of a mixture of synthetic fibers and glass fibers, the mixing ratio can be selected to suit the specific filtration application.

[0030] The filtration medium can be single-layered or multi-layered; for example, a so-called two-component or multi-component headbox can be used. In a two-component or multi-component headbox, a fiber slurry of a predetermined fiber type or a predetermined mixture of fiber types is poured onto a pre-existing or forming nonwoven fabric. The base fiber fabric can, in particular, have further layers that can be joined, for example, by bonding processes, especially thermal joining processes, such as lamination or ultrasonic welding.

[0031] Preferably, in a two- or multi-layered structure, the clean-side layer, or both the clean-side and the dirty-side layer—in other words, one or the outermost layer—can be designed as a grid structure (drainage grid). This further stabilizes the overall structure and ensures that the pleats remain optimally positioned during application. The thickness of the filter medium can, for example, range from 0.3 to 5 mm. The air permeability is preferably between 200 and 3000 l / m². 2 s.

[0032] Synthetic or glass fiber media are preferred, for example, for so-called lifetime applications, such as gearbox oil filtration.

[0033] Finally, it is preferred that the fold edge height is in a range between 2 mm and 100 mm, preferably 4 mm and 80 mm, and particularly preferably between 8 mm and 50 mm.

[0034] Last but not least, it is preferred that the fluid filter is designed as a suction-side transmission oil filter.

[0035] This allows the performance of the oil management system in an engine to be improved.

[0036] Alternatively, the liquid filter according to the invention is used in a "pressureless" system, i.e., a system without a pump. In this case, the liquid is not forced or drawn through the filter under pressure, but rather passes through the filter medium by gravity. Due to the optimal use of installation space, the pressure loss across the filter is particularly low, making it especially suitable for pressureless or pumpless operation.

[0037] The fluid filter according to the invention is particularly advantageously used in the e-axle of a motor vehicle. The e-axle combines the motor, transmission, axle, and power electronics in a single component and is used in vehicles with electric or hybrid drives. The transmission is supplied with transmission oil, some components of which require a specific oil purity. The fluid filter according to the invention filters the transmission oil. The impure oil is fed to the inlet surface of the fluid filter, seeps through the filter medium to the bottom of the filter housing, and exits through one or more outlets. The filtered transmission oil is then supplied to the relevant components. Brief description of the drawings

[0038] Further advantages become apparent from the following description of the drawings. The drawings illustrate exemplary embodiments of the invention. The drawings, description, and claims contain numerous features in combination. A person skilled in the art will expediently consider the features individually and combine them into meaningful further combinations. The following are shown as examples: Fig. 1 a first embodiment of a liquid filter according to the invention in a first installation space; Fig. 2 a second embodiment of a liquid filter according to the invention in a second installation space; Fig. 3 a third embodiment of a liquid filter according to the invention in a third installation space; Fig. 4 a fourth embodiment of a liquid filter according to the invention for a fourth installation space; Fig. 5 a sectional view of the embodiment according to Fig. 4; Fig. 6 a perspective view of a fifth embodiment of a liquid filter according to the invention for a fifth installation space; Fig. 7 a top view of the embodiment according to Fig. 6; Fig. 8 a sectional view of the embodiment according to Fig. 7; Fig. 9 a perspective view of a sixth embodiment of a liquid filter according to the invention for a sixth installation space; Fig. 10 a top view of the embodiment according to Fig. 9; Fig. 11 a sectional view of the embodiment according to Fig. 10; Fig. 12 a perspective view of an embodiment of a liquid filter for a seventh installation space; Fig. 13 a top view of the embodiment according to Fig. 12; Fig. 14 a sectional view of the embodiment according to Fig. 13; Fig. 15 a perspective view of an embodiment of a liquid filter for an eighth installation space; Fig. 16 a top view of the embodiment according to Fig. 15; Fig. 17 a sectional view of the embodiment according to Fig. 16; Fig. 18 a perspective view of an embodiment of a liquid filter for a ninth installation space; Fig. 19 a top view of the embodiment according to Fig. 18; Fig. 20 a sectional view of the embodiment according to Fig. 19; Fig. 21 a perspective view of a liquid filter with filter pot and cover grid. Embodiments of the invention

[0039] The figures merely show examples and are not to be understood as limiting.

[0040] Fig. Figure 1 shows a liquid filter 1. The liquid filter 1 has a bellows 2 formed by a plurality of pleats 3 embedded in a filter medium. The liquid filter 1 further comprises a housing into which the bellows 2 is inserted. The housing is preferably made of plastic and can be an injection-molded part. The bellows 2 is permanently attached to the housing, for example, by gluing. Therefore, if a replacement is necessary, the entire liquid filter, including the housing, is replaced. Alternatively, the bellows 2 can also be arranged in a replaceable manner within the filter housing.

[0041] Furthermore, in Fig. 1. It can be seen that the bellows 2 is formed from a first bellows section 4 and a second bellows section 5. It can also be seen (see immediately below) that Fig. 2) a third bellows section 6 may be provided. Generally speaking, the bellows 2 can therefore be composed of any number of different bellows sections. These different bellows sections can be connected to each other by bellows transition sections, as is the case with the bellows transition section 7 (see below). Fig. 5) is shown by way of example.

[0042] The liquid filter 1 is limited in its upward extent in a direction of gravity by a housing cover with a freeform ceiling surface 8. The shape of this freeform ceiling surface 8 depends on the available installation space in the application. It will therefore generally deviate from simple basic geometric shapes, such as rectangles or similar. In the example of the Fig. 1. The freeform ceiling surface 8 is formed from a first freeform ceiling surface section 9 and a second freeform ceiling surface section 10. A third freeform ceiling surface section 11 may also be provided, for example (see below). Fig. 2) Generally speaking, the freeform ceiling surface 8 can therefore be composed of any number of different freeform ceiling surface sections. These freeform ceiling surface sections can be connected to each other by freeform ceiling surface transition sections.

[0043] It is in Fig. It can be seen that the fold edge height is designed differently above a basic freeform surface 12. In the first freeform ceiling surface section 9, in which the first bellows section 4 is located, a first fold edge height is provided that is matched to the installation space height in the first freeform ceiling surface section 9. Furthermore, in the second freeform ceiling surface section 10, in which the second bellows section 5 is located, a second fold edge height is provided that is matched to the installation space height in the second freeform ceiling surface section 10. The distance of the fold edges from the freeform ceiling surface is different in the first bellows section 4 and the second bellows section 5, but constant within each respective bellows section 4, 5. The filter bellows 2 is formed in one piece and yet has different filter bellows sections 4, 5 with different fold edge heights.The fold edge height can be variable within the bellows 2; folds 3 with different fold edge heights can be present. The bellows 2 can thus be flexibly adapted to the available installation space.

[0044] In Fig. Figure 2 shows a similar second embodiment. Here, a total of three different bellows sections 4, 5, 6 are provided in three different freeform ceiling surface sections 9, 10, 11. It can again be seen that the fold edge heights in the different bellows sections 4, 5, 6 are adapted to the height of the freeform ceiling surface sections 9, 10, 11. For this purpose, identical fold edge heights are provided in the first bellows section 4 and the third bellows section 6; a different fold edge height is provided in the second bellows section 5, which is smaller than the fold edge height in the first bellows section 4 and the third bellows section 6. Again, the bellows 2 is flexibly adapted to the installation space.

[0045] In Fig. Figure 3 shows a similar embodiment. Here, it is particularly evident that the one-piece bellows 2 has a multitude of different fold edge heights that follow the contour of the freeform ceiling surface 8. This results in a bellows 2 with a trapezoidal cross-section that is optimally fitted into the available installation space. It is also particularly evident that the fold edge heights can vary even within sections, for example, between the first bellows section 4 and the third bellows section 6, in order to adapt to the available installation space.

[0046] In Fig. Figure 4 shows another embodiment of a liquid filter 1. Here, the base freeform surface 12 is bounded by a side freeform surface 13, which has a curved side freeform surface section 14. The shape of the filter housing corresponds to the shape of the installation space, i.e., the base freeform surface corresponds to the shape of the bottom surface of the housing and the side freeform surface corresponds to the shape of the side wall of the housing.

[0047] This is particularly relevant in Fig. 5 showed that the basic freeform surface 12 in the embodiment of the Fig. 4 has a step. The course of the step corresponds to the bellows transition section 7. In this bellows transition section 7, the distance between two adjacent first fold edges 15, 16, 17 differs from the distance between adjacent second fold edges 18, 19, 20 in the first bellows section 4 and the second bellows section 5. In the case shown, the distance between the first fold edges 15, 16, 17 is greater than the distance between the second fold edges 18, 19, 20. Thus, the folding of the bellows 2 varies across its base surface to allow adaptation to given installation space structures. Furthermore, in Fig. 5. It can be seen that by adjusting the folding edge height or the folding of the bellows 2, the integration of inserts or attachments, such as a valve 21 in this case, can be facilitated. The bellows 2 is attached to the side freeform surface 13 by means of compression.

[0048] Overall, the available height above the base freeform surface 12 is optimally utilized within the existing installation space. The filter performance of the liquid filter 1 is improved. A filter area optimized in relation to the installation space is available.

[0049] Improved separation efficiency can be achieved. The service life or service interval of liquid filter 1 can be extended.

[0050] In addition to optimizing the use of available installation space, the bellows base surface itself can also be adapted, either as an alternative or in addition to adjusting the fold edge height above the basic freeform surface 12. For this purpose, fold end faces 22, 23, 24 of the bellows 2 are adapted to a profile of the side freeform surface 13 facing them, and in particular to a curved side freeform surface section 14. This principle is described in Fig. 6, Fig. 7, Fig. 8, Fig. 9, Fig. 10, Fig. 11, Fig. 12, Fig. 13, Fig. 14, Fig. 15, Fig. 16, Fig. 17, Fig. 18, Fig. 19 to Fig. 20 illustrated.

[0051] This involves Fig. 6, Fig. 9, Fig. 12, Fig. 15 and Fig. Figure 18 shows a perspective view of the liquid filter 1, which is fitted into a freeform side surface 13 with at least one curved freeform side surface section 14. The freeform side surfaces 13 and freeform side surface sections 14 shown can be a lateral frame of the bellows, e.g., in the form of a side band, or a side wall of a housing that is not fully shown. The contours always correspond to those of the installation space.

[0052] In Fig. 7, Fig. 10, Fig. 13, Fig. 16 and Fig. Figure 19 is then a top view of the respective embodiments of the aforementioned Fig. 6, Fig. 9, Fig. 12, Fig. 15 and Fig. Figure 18 shows that the bellows 2, with its base surface, completely and optimally fills the base freeform surface 12. The fold ends 22, 23, 24 are attached to the side freeform surface 13 or the curved side freeform surface section 14 along the circumferential contour of the base freeform surface 12. This attachment can be achieved by clamping, pressing, gluing, welding, or overmolding the fold ends 22, 23, 24 to the side freeform surface 13 or the curved side freeform surface section 14. The bellows 2 can also be finished or framed by bonded side bands. Through a joining process (e.g. gluing, welding, etc.), the flexible bellows 2 can then be inserted into a housing pot with side walls corresponding to the freeform side surface and installed in the available installation space.

[0053] Overall, the available freeform surface 12 within the existing installation space is optimally utilized by means of the bellows base area. The filter performance of the liquid filter 1 is improved. The pressure loss is minimized. A larger filter area is available. Better separation efficiency can be achieved. The service life or service interval of the liquid filter 1 can be extended.

[0054] Finally, in Fig. 8, Fig. 11, Fig. 14, Fig. 17 and Fig. 20 each a sectional view of the Fig. 7, Fig. 10, Fig. 13, Fig. 16 and Fig. Figure 19 shows that the filter bellows 2 is adapted to the available height of the installation space as well as to the available basic freeform surface 12.

[0055] In Fig.Figure 21 shows a filter 1 for an e-axle of an electric or hybrid vehicle. The filter 1 serves to filter the transmission oil of the e-axle's gearbox. The filter 1 is designed for pressureless operation without a pump; that is, the transmission oil is not pumped to the filter 1 and forced or drawn through the filter medium under pressure. Accordingly, the filter 1 has a housing 100 that is open on the upstream side, with a housing pot 101, which is closed by a cover 102 designed as a grid. The oil can flow through the entire area of ​​the cover to the bellows 2 inside the housing 100. The cover 102 is attached to the housing pot 101 by means of a snap-fit ​​connection. The filter element is designed as a bellows 2 with pleated end faces framed by a side band and is inserted into the housing pot 101, with the side bands forming the longitudinal seal against the housing pot 101.The edge folds can be pressed together to provide a transverse seal between the housing pot 101 and the cover 102. Additional sealing, for example by means of a circumferential sealing ring as with air filter elements, is not required. Since there is no pump, the oil is forced through the filter medium solely by gravity. The bellows 2 is therefore only subjected to minimal pressure (that exerted by the oil itself) and requires only minimal protection against deformation. The transmission oil can be fed evenly to the upstream side of the filter element via the grid. The folding creates numerous spaces in which the supplied oil can collect, thus preventing it from overflowing the filter housing 100, unlike in a design with a sponge-like filter medium.The filtered oil can exit the filter 1 through one or more outlets 103 in the housing 101 and be supplied to the required locations, for example, a bearing. Not shown is a vent opening through which air located in the closed space between the bellows 2 and the housing 101 can escape. Alternatively, the bellows 2 can be permanently bonded to the housing 101. In this case, no lid is required to secure the filter element. The filter 1 then comprises a lidless housing.

[0056] The rectangular filter housing shown is a schematic representation of a housing for a bellows-type filter for pump-free operation. Depending on the available installation space, the side walls, base, and / or lid will have a correspondingly adapted contour or shape.

Claims

[1] Liquid filter (1), in particular oil filter, for filtering a liquid, in particular an oil, which has a raw-side inlet surface and a clean-side outlet surface which are connected to each other by means of a flow path, and a filter body which has a filter medium folded to form a bellows (2) with a plurality of folds (3) which extends between two edge folds, wherein each fold (3) has a first fold leaf and a second fold leaf which adjoin each other at a fold edge, a fold edge height and two opposing fold end faces (22, 23), and wherein the liquid filter (1) is designed to be installed in a space which defines a space volume by means of a base freeform surface (12), a ceiling freeform surface (8) and a side freeform surface (13),wherein the bellows (2) is formed in one piece and at least two of the plurality of folds (3) have a different height, wherein the fold edge heights are adapted to an uneven or inclined contour of the top freeform surface (8) and / or the base freeform surface (12), and wherein the fold end faces (22, 23, 24) of at least two folds (3) are adapted to a contour of the side freeform surface (13) facing them, wherein the shape of an envelope of all fold end faces (22, 23, 24) and the edge folds deviates from a rectangle, wherein the bellows (2) is formed entirely from a single material, wherein the bellows (2) is not attached to the housing by means of overmolding, wherein the bellows (2) is inserted into a housing pot (101) with a side wall and a bottom surface, wherein the shape of the side wall corresponds to the shape of the side freeform surface (13),and wherein the shape of the bottom surface corresponds to the shape of the basic freeform surface (12), wherein at least one fold (3) on the raw-side inflow surface and / or on the clean-side outflow surface and / or at least one fold end face (22, 23, 24) is attached to the side wall by clamping, pressing, gluing or welding, , characterized by , that the bellows (2) has at least two bellows sections (4, 5, 6) with different fold edge heights, which are arranged to leave a predetermined distance from the ceiling freeform surface section (9, 10, 11) and / or the housing cover (102) in at least two ceiling freeform surface sections (9, 10, 11) of the ceiling freeform surface (8). and / or the bellows (2) has at least two bellows sections (4, 5, 6) with different fold edge heights, which are arranged to leave a predetermined distance from the basic freeform surface section or the housing pot bottom surface in at least two basic freeform surface sections of the basic freeform surface (12). [2] Liquid filter (1) according to claim 1, characterized by , that the housing pot (101) is closed or can be closed with a housing lid (102) whose shape is adapted to the ceiling freeform surface (8). [3] Liquid filter (1) according to claim 1 or 2, characterized by , that the filter (1) has a housing cover (102) for connecting to the housing pot (101), which is designed as a grid. [4] Liquid filter (1) according to claim 1, characterized by, that a distance between two adjacent first fold edges (15, 16) in a bellows transition section (7) between the at least two bellows sections (4, 5, 6) is formed differently from a distance between two adjacent second fold edges (18, 19) in a bellows section (4, 5, 6). [5] Liquid filter (1) according to any one of claims 1 to 4, characterized by , that the envelope of all fold end faces (22, 23, 24) has at least one curved section adapted to a curved side freeform surface section (14) of the side freeform surface (13). [6] Liquid filter (1) according to any one of claims 1 to 5, characterized by that the fold edge height is in a range between 2 mm and 100 mm, preferably 4 mm and 80 mm, particularly preferably between 8 mm and 50 mm. [7] Use of a liquid filter (1) according to any one of claims 1 to 6 as a transmission oil filter, in particular as a pressureless transmission oil filter. [8] Use of a liquid filter (1) according to any one of claims 1 to 6 for filtering transmission oil of an e-axle for a motor vehicle with a transmission.

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