Filter Device

Abstract

The present invention provides a filter device having a filter housing 10 comprising at least one housing portion 12 and a further housing portion 14 detachably connected to the first housing portion 12 and containing a filter element 16, the filter device having a valve device 18 which further separates the first housing portion 12 and the second housing portion 14 from each other to quickly separate the flow paths between one connection point 22 in the filter housing 10 for supplying unfiltered media and another connection point 24 in the filter housing 10 for discharging filtrate, the valve device 18 being connected to the first housing portion 12. and the further housing part (14) are connected to each other, the valve device (18) having a valve spool (26) that is longitudinally movable in at least one of the housing parts (12), and the valve spool (26) moves from an open position in which the valve spool (26) opens the flow path (20) to a position in which the valve spool (26) closes the flow path (20) and from a position in which the valve spool (26) closes the flow path (20) to a position in which the valve spool (26) opens the flow path (20) under the influence of a specific installation situation of the filter element (16).

Description

[Technical Field]

[0001] The present invention relates to a filter device having a filter housing consisting of at least one housing part and a further housing part that houses a filter element and is detachably connected to the one housing part, wherein the filter device has a valve device that, when the one housing part and the further housing part are separated from each other, quickly isolates a flow path between one connection point in the filter housing for supplying unfiltered media and another connection point in the filter housing for discharging filtrate, and the valve device quickly opens the flow path when the one housing part and the further housing part are connected to each other. [Background technology]

[0002] EP 4088801 A1 discloses a filter device with a filter housing having two connection points, i.e., an inlet for unfiltered media and an outlet for filtrate, and a replaceable filter element. The filter housing is provided with a valve device that, in an open position, allows fluid flow between one of the two connection points and the filter element, and prevents this fluid flow in a closed position. The valve device is movable between the open and closed positions by an actuator. This arrangement reliably prevents the flow of hydraulic fluid into the housing during filter element replacement, even when the hydraulic line is pressurized. For this purpose, the valve device has an inlet valve arranged in the fluid flow between the inlet side and the outside of the filter element, and a further outlet valve arranged in the fluid flow between the inside and the outlet of the filter element. Known solutions for preventing fluid flow during filter element replacement use two independent valves that are spring-loaded toward the closed position.

[0003] Patent Document 2 (German Patent No. 10214000490) discloses a filter device comprising a filter housing defining a main axis, the filter housing being capable of accommodating at least one replaceable filter element, the filter housing having a housing container surrounding each filter element, and a housing head releasably attachable to the housing container, the housing head having at least one fluid guide for the outflow of filtrate, the valve device being associated with the fluid guide, the valve device having a valve plate that blocks the outflow of filtrate in a closed position and allows the outflow of filtrate in a released position, the valve plate being in a locked position and the valve plate being in a closed position and the valve plate being in a locked ... The present disclosure discloses a filter device comprising a locking device having a locking member for locking a valve plate of the device, the locking member being movable from a locked position to an unlocked position by means of tabs provided on each filter element, the filter elements mechanically acting on the locking member during attachment of the housing head to the housing container when the housing container is in its functional position, the locking member being mounted axially displaceable along a main axis for movement between the locked and unlocked positions within the housing head, and being movable to the unlocked position by contact with respective tabs on the filter elements when the housing head is attached.

[0004] Furthermore, the annular body of the locking member interacts with the valve plate via a spring arrangement having a predeterminable number of spring fingers, the spring fingers being fixed at one end to the retaining ring in an arrangement distributed around the flow opening, the free ends of which extend outside the peripheral area of ​​the valve plate when the locking member is in the unlocked position, and the annular body of the locking member having a conical control surface on its inner circumference which, when the locking member is moved to the locked position, abuts the spring fingers and is brought radially inward to a position where the free end overlaps the edge of the valve plate, which is the closed position.

[0005] In this way, the filter device is taken out of operation to allow for filter element replacement, and when the operating fluid pressure is removed, the valve plate of the valve device, which shuts off the fluid supply, returns to its closed position. Because the valve plate acts parallel to the direction of fluid flow, any transverse forces are eliminated, thereby reducing frictional forces and therefore the required valve actuation force.

[0006] This in turn leads to reduced material stresses and therefore allows for the use of cost effective materials such as plastic materials. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] European Patent Application Publication No. 4088801 [Patent Document 2] German Patent No. 10214000490 Summary of the Invention [Problem to be solved by the invention]

[0008] Based on this prior art, it is an object of the present invention to provide a filter device that is improved over the prior art and that, with fewer components, allows for reliable automatic shutoff of fluid lines connected to the filter device when replacing a filter element. [Means for solving the problem]

[0009] This problem is solved by a filter device having the overall features of claim 1. According to the invention, the valve device includes a valve spool that is longitudinally movable in at least one of the housing sections and that, under the influence of the installation conditions of the respective filter elements, moves from an open position where the valve spool releases the flow path to a position where the valve spool blocks the flow path, and from a position where the valve spool blocks the flow path to a position where the valve spool releases the flow path. By using a valve spool instead of a spring-loaded check valve with a valve disc, as shown in the prior art, a device solution is obtained that prevents the unwanted flow of fluid, such as hydraulic fluid, from a line connection when replacing a filter element. In this respect, reliable automatic shutoff of the connected line is achieved during filter element replacement, replacing a used filter element with a new one. Overall, the use of a valve spool provides a cost-effective, filter-integrated solution, eliminating the need for additional shutoff devices, such as shutoff valves, check valves, and fittings. Furthermore, permanent pressure losses that would otherwise be necessitated by check valves or additional fittings in the prior art are avoided.

[0010] When the filter element is removed, the valve spool always moves to a position that blocks the flow path between the fluid connections, thereby reliably preventing unintentional operation without the filter element, which could damage the hydraulic circuit and its connected components, thus fulfilling the slogan "no element, no flow." Therefore, operational errors and malfunctions are also eliminated.

[0011] In one embodiment of the filter device, the valve spool has a central channel through which the transverse channels pass. In the open position, the valve spool establishes a fluid connection between the central channel and one of two connection points in the filter housing as part of the flow path, and in the closed position, closes the fluid connection. Preferably, the valve spool also has a channel guide on its outer periphery. In the open position, the valve spool establishes a fluid connection between the other of the two connection points and the outer periphery of the filter element as part of the flow path, and in the closed position, closes the fluid connection. In this way, the valve spool achieves a transverse force-free and obstruction-free operation between its two "open" and "closed" functional positions. The aforementioned channel-like guidance of the flow path achieves a particularly gentle filter operation, with the flow through the filter element, which is supported on its inner periphery by a fluid-permeable support, such as a support tube, from the outside to the inside. That is, unfiltered fluid is supplied to the outer periphery of the filter element, and cleaned fluid in the form of filtrate is discharged to the inner periphery of the filter element.

[0012] In a particularly preferred embodiment, it is further provided that the valve spool has, on its side facing the filter element, a connecting element, in particular in the form of an external thread, which releasably interacts with a further connecting element, in particular in the form of an internal thread, on the filter element to form a threaded connection in a particularly releasable manner. In this way, the required connection between the filter element and the valve spool can be produced in a cost-effective and space-saving manner.

[0013] For trouble-free operation, it is also advantageous if the valve spool is preloaded in the direction of its shut-off position by an energy storage device, in particular in the form of a compression spring.

[0014] For the application of a centric force on the valve spool, loosening the material, it is advantageous if the valve spool and the filter element are arranged concentrically on the longitudinal axis of the filter housing of the filter device.

[0015] In a particularly preferred embodiment of the filter device according to the invention, it is provided that the valve spool together with the connection points and the associated parts of the flow paths is accommodated in the filter head as one housing part, and the filter element is accommodated in a filter vessel as a further housing part, which can be releasably fastened, in particular screwed, to the first housing part. In this way, the fluid control device with the associated piping can be fixed to the filter head, which remains stationary on the hydraulic circuit, but the replaceable filter element can be separated, in particular unscrewed, from the filter housing via a separate filter vessel.

[0016] Preferably, when the two housing parts are assembled, in particular when screwed together, and when the filter element is inserted, the central channel of the valve spool opens into the interior of the hollow cylindrical filter element, so that cavitation due to any generation of turbulence in the fluid flow is avoided.

[0017] In a further preferred embodiment of the filter device according to the invention, a friction coupling is present in the further housing part. When the filter element is screwed onto the valve spool as part of the screwing process of the further housing part onto the first housing part, the friction coupling terminates the screwing process for the filter element and allows the screwing process for the further housing part to continue. As part of the unscrewing process, the friction coupling acts as a locking coupling, similarly allowing the unscrewing process for the further housing part with the filter element in the reverse direction. This increases the reliability of the overall installation by ensuring that the filter element is first secured to the valve spool in a defined manner before the further housing part in the form of a housing vessel is secured to the first housing part in the form of a filter head. In the reverse direction, the friction coupling, which then functions as a locking coupling, is used to unscrew both the filter vessel and the filter element from the filter head and its valve spool. The threaded element used here can have its pitch and / or number of turns varied to always ensure that the filter element is already secured to the valve spool of the housing head before the housing vessel is fully screwed onto the housing head.

[0018] In a further preferred embodiment of the filter device according to the invention, a bypass valve engaging in the transverse channel is provided, which is connected in part of the flow path between the two connection points. In this way, in the case of a so-called blockage of a filter element, which is already heavily clogged with particle contamination and no longer allows the flow of fluid, it is possible to bypass the unfiltered medium flow so that it passes directly from the unfiltered side to the filtered side of the filter device through the opened bypass valve, in order to maintain its function. This bypass valve is generally harmless to the hydraulic circuit and its connected components, since many cleaning processes of the fluid have already been carried out by the not-yet-clogged filter element, and therefore the transported fluid is clean.

[0019] In the following, the filter device according to the invention will be explained in more detail using an embodiment according to the drawings, in which the figures are shown in principle and are not drawn to scale. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 1 shows the entire filter device in longitudinal section. [Figure 2] FIG. 2 shows an enlarged image portion of the circle shown in FIG. [Figure 3] FIG. 3 is a partial view of the filter device rotated 90 degrees in the direction of the arrow in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0021] 1 shows a filter device according to the present invention as a whole in a longitudinal section. The filter device comprises a filter housing 10 having a housing part 12 and a second housing part 14 that houses a filter element 16 and is releasably connected to the first housing part 12. The filter device further comprises a valve device 18 that, upon further separation of the two housing parts 12, 14 from one another, quickly disconnects a flow path 20 between a first connection point 22 in the filter housing 10 for supplying unfiltered media and a further second connection point 24 in the filter housing 10 for discharging filtrate, and quickly reopens the corresponding flow path 20 when the two housing parts 12, 14 are reconnected. This will be explained in more detail below. The valve device 18 has a valve spool 26 that is longitudinally movable within the first housing part 12 and moves from an open position that releases the flow path 20 to a position that blocks the flow path 20, and from a position that blocks the flow path 20 to an open position that releases the flow path 20, under the influence of the respective installation conditions of the filter element 16.

[0022] As FIG. 1 further shows, the valve spool 26, designed in the manner of a hollow cylinder, has a central channel 28 pierced in its upper end region by a transverse channel 30 with a smaller free cross-section when viewed from the perspective of FIG. 1 . For this purpose, the transverse channel 30 opens at one free end into the second connection point 24, while its other free end enters a receiving chamber 32 that serves to accommodate a bypass valve 34 that is inserted into the first housing part 12 from above, in particular, screwed in from above. In its open position shown in FIG. 1 , which frees the flow path 20 to cross the central channel 28 through the transverse channel 30, the valve spool 26 has two holes 36 that are arranged at the same height in the valve spool 26 and are diametrically opposite each other relative to the longitudinal axis 38 of the second housing part 14 together with the filter element 16. The free diameter of the two holes 36 essentially corresponds to the free diameter of the transverse channel 30. When the valve spool 26 assumes its position blocking the flow passage 20, it moves downwards in the direction of Fig. 1 with the help of an energy storage device in the form of a compression spring 40, which is only possible if at least the filter element 16 is removed from the filter device. During its downward movement, the valve spool 26 closes the transverse channel 30 by means of an annular wall region 42 which is located opposite the valve spool 26 and above the two holes 36 along the two openings formed by the two holes 36.

[0023] The valve spool 26 further has a channel guide 44 on its outer periphery, which forms a rectangular annular groove in cross section that surrounds the valve spool 26 and whose base is formed by the remaining hollow cylindrical wall 46 of the valve spool 26. In the open position of the valve spool 26 shown in FIG. 1, the channel guide 44 opens into a horizontally extending fluid channel 48, which opens at its other free end into the first connection point 22, which has a wider diameter. A branch channel 50, closed at its upper free end by the bypass valve 34, extends vertically in the transition region between the fluid connection point 22 and the fluid channel 48.

[0024] On the other side opposite the fluid channel 48, the channel portion 52 opens into the circumferential channel guide 44 in the one housing part 12, and at its other free end into a vertically extending transition channel 54, and at its lower free end into an unfiltered medium chamber 56 in the second housing part 14, which unfiltered medium chamber 56 is bounded on the outside by the inner wall of the second housing part 14 and on the inside by the outer circumferential surface of the filter element 16. At this point, the second further housing part 14 is open at its upper end, at which point a kind of filter vessel is created, which at this point is screwed with its external thread along thread 58 into the internal thread of the first housing part 12, forming a kind of filter head. In particular, the filter head is fluidly connected via its two connection points 22, 24 to the piping of a hydraulic circuit (not shown in detail). In this respect, the housing head forms the stationary part of the filter arrangement, and the filter vessel 14 with the filter element 16 can be unscrewed from the filter head as the movable part of the filter arrangement, so that an interlocking connection is formed between one housing part 12 and the other housing part 14. To ensure that the threaded connection is pressure-tight via the threaded part 58, a sealing device 60 in the form of at least one O-ring can be arranged at the free end of the filter vessel 14.

[0025] The filter element 16 typically comprises a pleated filter medium 62 constructed from several layers of elements extending between an upper end cap 64 and a lower end cap 66, the latter not shown in FIG. 3 for ease of illustration. Flow through the pleated filter medium 62 is from the exterior to the interior, starting from the unfiltered region 56, and the pleated filter medium 62 is supported on its inner periphery in the usual manner on a fluid-permeable support in the form of a support tube 68; for ease of illustration, only a portion of the circular fluid passages extending in a longitudinal row at a predeterminable distance from one another between the upper and lower end caps 64, 66 are shown. The filter element 16 encloses a hollow cylindrical filtration chamber 70, which is permanently fluidly connected to the central channel 28 in the illustrated open position of the valve spool 26. However, the filtration chamber 70 is sealed fluid-tight at its bottom by the closed lower end cap 66.

[0026] The flow path 20 within the first housing portion 12, as viewed in the direction of fluid flow, consists of a first connection point 22, a horizontally extending fluid channel 48, an annular channel guide 44 within the valve spool 26, a channel portion 52 extending oppositely from the channel 48, a vertically extending transition channel 54, an unfiltered media chamber 56, a fluid passage point within the filter media 62, the filter media 70, the vertical central channel 28, the holes 36, the transverse channel 30, and a second further fluid connection point 24. Furthermore, the additional hole 36 in the valve spool 26, together with the transverse channel 30 extended at this point and the receiving chamber 32 for the bypass valve 34 and the further branch channel 50 extending perpendicularly, form a bypass passage 72 which is activated when the filter medium 62 is blocked, the flow path 20 is blocked in this area, and under increasing inlet pressure at the first connection point 22, the valve element of the spring-loaded check valve as bypass valve 34 opens, bypassing the filter element 16 while releasing the direct fluid connection between the first connection point 22 and the second connection point 24. In this case, with the bypass valve 34 open, the fluid branches off from the first connection point 22 and the channel 50 and flows through the corresponding receiving chamber 32 into the transverse channel 30 and thus through the two holes 36 and the central channel 28 to the outlet side, i.e., to the second connection point 24.

[0027] A prerequisite for each flow path 20, 72 is that the valve spool 26 is in its open position as shown in Figure 1. However, when the tubular valve spool 26 is in its closed position when the filter element 16 is removed, the channel guide 44 disengages from the adjacent fluid channels 48, 52, 54 of the flow path 20, and both the horizontally extending fluid channel 48 and the horizontally extending channel portion 52 at the same height are overlapped by the wall portion 74 of the valve spool 26 located above and blocking them, so that the flow path 20 is also completely blocked at this point. The compression spring 40 for controlling the valve spool 26 has one free end supported on a housing plug 76 that can be screwed into the housing portion 12, and its other free end supported on a closure portion 78 that blocks the central channel 28 above the two holes 36.

[0028] 2, the filter element 16 is threadably guided via an internal thread 80 into an external thread 82 at the lower end of the valve spool 26, thus forming a second additional thread 84 coaxially aligned with the first thread 58 between the valve spool 26 and the filter element 16. In particular, the axial length of the additional thread 84 is shorter than the length of the first thread 58 between the two housing parts 12, 14. The internal thread 80 of the upper end cap 64 extends in its upper end region along the inner periphery of the support tube 68 for a predeterminable distance. In the extension of this female thread 80, an edge 86 protrudes upwards when viewed in the direction of FIG. 2, which edge acts as a stop edge in the fixed state of the filter element 16 so as to contact the underside of the valve spool 26 in its open position shown in FIG. 1, and for this purpose the male thread 84 is correspondingly reduced in diameter compared to the contact surface 87 on the underside of the valve spool 26.

[0029] Furthermore, a friction coupling 88 interacting with a further compression spring 90 is provided at the lower end of the filter element 16. In this case, the friction coupling 88 is a component of the further housing part 14, and when the filter element 16 is screwed onto the valve spool 26 as part of the screwing process of the further housing part 14 into the one of the housing parts 12, the friction coupling 88 completes the screwing process of the filter element 16, i.e., the filter element 16 precisely contacts via its edge 86 with a contact surface 87 of the valve spool 26, and the valve spool 26 slides back from the lower valve or spool position in which it concomitantly blocks the flow path 20 and against the action of the compression spring 40 into the open position according to Figures 1 to 3. After the further threaded portion 84 is fully formed through the female threaded portion 80 and the male threaded portion 82, the friction coupling 88 allows the threading process for the further housing portion 14 to continue into the housing portion 12 until the threaded portion 58 between the two housing portions 12, 14 is also fully formed, and the further housing portion 14 is in its fully threaded position as shown in Figures 1-3.

[0030] In the opposite case, i.e. in the opposite direction of rotation of the further housing part 14, the friction coupling 88 is combined in one structural unit and acts here as a fixed coupling, allowing equally the process of unscrewing the further housing part 14 together with the filter element 16 from the one housing part 12 or from the external thread 82 of the valve spool 26. The technical solution of the friction coupling 88, which can be converted into a fixed coupling in the opposite direction of rotation and back again, is described in full detail in EP 3352876 and will not be discussed in further detail here.

[0031] In any case, the external thread 82 is reduced in diameter compared to the other outer diameters of the valve spool 26 so that the free end of the annular rim 86 of the upper element cap 64 can rest on the free end face of the valve spool in the installed state. In this way, during the process of screwing the filter element 16 onto the valve spool 26, the valve spool 26 can be moved upward against the action of the compression spring 40. For this purpose, the outer diameter of the outer periphery of the valve spool 26 essentially corresponds to the outer diameter of the rim 86 of the element cap 64 and forms a stop. Otherwise, the outer diameter of the valve spool 26 remains essentially constant, as does its inner diameter, which forms the central channel 28. To enable the integration of a friction coupling 88, which also functions as a fixed coupling, into the filter housing 10, the cylindrical housing shell of the further housing part 14 has, on its underside, a container holder 92 that is screwed to the underside of the further housing part 14 so that the housing part 14 can be driven both in the rotational direction and in the screwing direction by a rotational movement on the container holder 92. 1 makes clear that the valve spool 26 cannot be in the open or functional position shown unless the filter element 16 is inserted into the further housing portion 14. Rather, under the influence of the compression spring 40, the valve spool 26 is then forced downward into the interior of the housing portion 14, thereby closing the aforementioned channel portion of the flow path 20, and at this point, the bypass passage 72 is also closed. Only when the filter element 16 is inserted will the valve spool 26 be in the position shown in the figure, the flow path 20 be open for future filtration by the filter element 16, and the bypass valve 34 be able to operate as needed.

[0032] 3, along arrow 93 in FIG. 1, illustrates the lateral engagement of a locking screw 94, which is secured within the first housing section 12, into the valve spool 26. The free end of the locking screw 94 engages with a longitudinal channel 96 of a predeterminable length that is formed on the outer periphery of the valve spool 26. The valve spool 26 is longitudinally movable within its associated housing opening 98 in the housing section 12 via the corresponding locking screw 94 along with the longitudinal channel 96; i.e., the valve spool 26 is also held in the lowermost, closed position within the housing receptacle 98 by the locking screw 94. In this case, the locking screw 94 abuts against the upper end of the longitudinal channel 98; otherwise, in the open position, it abuts against the lower end, as shown in FIG. 3. FIG. 3 also illustrates an annular groove 100 that forms the transition from the outer periphery of the valve spool 26 to its externally threaded portion 82. It is further apparent that the upper end of the filter media 62 is essentially flush with the imaginary extension of the upper outlet of the external threaded portion 82. Otherwise, in the open position of the valve spool 26, its underside at the transition area to the annular groove 100 is flush with the lower end of the housing receptacle 98 of the housing part 12.

[0033] The solution of the filter device according to the present invention avoids oil loss, eliminating the need to refill the filter element 16 when it is replaced. In addition to preventing the intrusion of oil contaminants into the clean side of the filter device, it has been shown that unintended air intrusion during element replacement can also be avoided. Furthermore, the connection solution via the various threads 58, and particularly via the thread 84, provides protection against duplication, thereby preventing the replacement of a poor-quality filter element 16. Furthermore, when replacing the filter element, unpleasant oil leakage from the line connections 22, 24 is avoided. To this end, the valve spool 26, located in the center of the filter head 12, automatically closes with the aid of gravity when the filter container 14 is removed. This is necessarily supported by the spring force of the compression spring 40. Therefore, the downward movement of the valve spool 26 occurs even when the filter container 14 is removed from the filter head 12. The connection of the longitudinally movable valve spool 26 to its actuator via the known friction coupling 88 has no equivalent in the prior art.

Claims

1. A filter device having a filter housing (10) consisting of at least one housing part (12) and a further housing part (14) detachably connected to said one housing part (12) and accommodating a filter element (16), The filter device has a valve device (18) that quickly separates a flow path between one connection point (22) in the filter housing (10) for supplying unfiltered media and another connection point (24) in the filter housing (10) for discharging filtrate by further separating the one housing part (12) and the further housing part (14) from each other, and the valve device (18) quickly opens the flow path (20) when the one housing part (12) and the further housing part (14) are connected to each other. The valve device (18) has a valve spool (26) that is longitudinally movable in at least one of the housing parts (12), and the valve spool (26) moves from an open position in which the valve spool (26) opens the flow path (20) to a position in which the valve spool (26) closes the flow path (20) and from a position in which the valve spool (26) closes the flow path (20) to a position in which the valve spool (26) opens the flow path (20) under the influence of a specific installation situation of the filter element (16).

2. 2. The filter device of claim 1, wherein the valve spool has a central channel through which a transverse channel passes, and the valve spool establishes a fluid connection between the central channel and at least one of the two connection points in the filter housing as part of the flow path in an open position of the valve spool, and closes the fluid connection in a closed position of the valve spool.

3. 3. The filter device according to claim 1, wherein the valve spool (26) has a channel guide (44) on its outer circumferential side, and in the open position, the valve spool (26) establishes a fluid connection between the other of the two connection points (22, 24) and the outer circumferential side of the filter element (16) as part of the flow path (20), and closes the fluid connection in the closed position.

4. 4. A filter arrangement according to claim 1, wherein the valve spool (26) has, on its side facing the filter element (16), a connecting element, in particular in the form of an external thread (82), which releasably interacts with a further connecting element, in particular in the form of an internal thread (80), on the filter element, forming a threaded connection, in particular in a releasable manner.

5. 5. A filter arrangement according to any one of claims 1 to 4, characterized in that the valve spool (26) is pretensioned towards its closed position by an energy storage device, in particular in the form of a compression spring (40).

6. 6. The filter device according to claim 1, wherein the valve spool (26) and the filter element (16) are arranged concentrically about the longitudinal axis (38) of the filter housing (10).

7. 7. A filter arrangement according to claim 1, characterized in that the valve spool (26) together with the connection points (22, 24) and the associated parts of the flow path (20) are accommodated in a filter head as the one housing part (12), and the filter element (16) is accommodated in a filter vessel as the further housing part (14), the further housing part (14) being releasably, in particular screwably, connected to the one housing part (12).

8. 8. The filter device according to claim 1, wherein, in an assembled state of the two housing parts (12, 14), with the filter element (16) inserted, the central channel (28) of the valve spool (26) opens into the interior (70) of the hollow cylindrical filter element (16).

9. A friction coupling (88) is present in the further housing part (14) so ​​that when the filter element (16) is threaded onto the spool (26) as part of the process of threading the further housing part (14) onto the one housing part (12), 9. The filter device according to claim 1, wherein the friction coupling (88) allows the threading process for the filter element (16) to be completed and the threading process for the further housing part (14) to be continued, and as part of the unscrewing process, the friction coupling (88) acts as a fixed coupling, which likewise allows the unscrewing process for the further housing part (14) with the filter element (16) in the opposite direction of rotation.

10. 10. The filter device according to claim 1, wherein a bypass valve (34) at least partially engaging the transverse channel (30) is connected to a portion of the flow path (20) between the two connection points (22, 24).

Images