Filter Housing of an Exchangeable Filter, Filter, Connecting Device, and Filter Device

Abstract

A filter housing has a housing pot accommodating a filter element. The filter housing has a connecting element connectable by a rotary and/or plug-in connection for connecting the filter with a connecting device. The filter housing has a securing ring forming a cup-shaped attachment section with a circumferential free rim. By rotary and/or plug-in movement, the attachment section is attached to an insertion section of the connecting device. The attachment section is provided with a sealing receptacle of a circumferential sealing device. The sealing receptacle is open in radial inward direction and has a radial sealing surface. The attachment section is connected at the free rim with the circumferential wall of the housing pot by crimping. The securing ring provides a first axial stop surface for an annular seal. A stop ring, inserted into the securing ring, provides a second axial stop surface for the annular seal.

Claims

1. A filter housing of an exchangeable filter of a filter device for liquids, the filter housing comprising: a housing pot configured to accommodate at least one filter element; at least one filter-associated connecting element configured to be connected by a rotary and/or plug-in connection relative to a connecting axis to a connecting device of the filter device for connecting the exchangeable filter; a securing ring disposed at an end face of the filter housing and forming a cup-shaped attachment section, wherein, by of a rotary and/or plug-in movement relative to the connecting axis, the cup-shaped attachment section is attachable to a corresponding insertion section of the connecting device; wherein the cup-shaped attachment section comprises a circumferential free rim at an open side of the cup-shaped attachment section and is connected at the circumferential free rim to a circumferential wall of the housing pot by a crimp connection; wherein the cup-shaped attachment section comprises a sealing receptacle of at least one circumferential sealing device configured to act sealingly at least radially in a radial direction relative to the connecting axis; wherein the sealing receptacle is open inwardly in the radial direction and comprises a radial sealing surface pointing inwardly in the radial direction and configured to support at least one annular seal; wherein the securing ring comprises a first at least part-circumferential axial stop surface for the at least one annular seal in an axial direction of the connecting axis; a stop ring inserted from the open side of the cup-shaped attachment section into the securing ring and providing a second at least part-circumferential axial stop surface for the at least one annular seal opposite the first at least part-circumferential axial stop surface in the axial direction.

2. The filter housing according to claim 1, wherein the securing ring is formed to follow closely with a predetermined axial extension the circumferential wall of the housing pot in a first section of the cup-shaped attachment section near the circumferential free rim, wherein the first section comprises a substantially cylindrical cross section, wherein the securing ring comprises, in a second section of the cup-shaped attachment section facing away from the circumferential free rim, a reduced diameter section that forms the first at least part-circumferential axial stop surface.

3. The filter housing according to claim 1, wherein the stop ring is pressed in from an end face of the filter housing into the securing ring

4. The filter housing according to claim 1, wherein the stop ring comprises a substantially Z-shaped cross section, wherein a leg of the Z is extending perpendicular to the virtual connecting axis and forms the second at least part-circumferential axial stop surface, wherein the leg of the Z is in an axial position where, in the radial direction externally, the crimp connection is located.

5. The filter housing according to claim 1, wherein the stop ring does not project farther into the securing ring in the axial direction than the crimp connection is extending in the axial direction away from the circumferential free rim.

6. The filter housing according to claim 1, wherein the crimp connection comprises a crimp that is bent in the radial direction outwardly and that does not produce on the circumferential free rim an inner cross section restriction relative to the circumferential wall of the housing pot.

7. The filter housing according to claim 1, further comprising a securing sleeve arranged coaxially on the cup-shaped attachment section at an open end face of the filter housing, wherein the securing sleeve has a central opening configured to receive at least partially in a mounted state of the filter a connecting element of the connecting device.

8. The filter housing according to claim 7, wherein the securing sleeve is formed monolithic in the securing ring as a coaxial bulge of the securing ring.

9. The filter housing according to claim 8, wherein the securing ring is a formed part.

10. The filter housing according to claim 7, wherein the securing sleeve extends in the axial direction at least to the level of the circumferential free rim.

11. The filter housing according to claim 10, wherein the securing sleeve ends in the axial direction at the same level as the circumferential free rim.

12. The filter housing according to claim 7, wherein the central opening is located in an end face of the securing sleeve, wherein a rim of the securing sleeve delimiting the central opening forms a first part of an anti-rotation securing device configured to interact with a second part of the anti-rotation securing device provided on the connecting element of the connecting device.

13. The filter housing according to claim 7, wherein the securing sleeve is resilient at least in the axial direction.

14. The filter housing according to claim 13, wherein the securing sleeve is comprised of a resilient material or has a geometry providing resilient properties.

15. The filter housing according to claim 13, wherein the securing sleeve is comprised of a resilient material and has a geometry providing resilient properties.

16. The filter housing according to claim 13, wherein the securing sleeve is comprised of a thin-walled sheet metal.

17. The filter housing according to claim 1, wherein the cup-shaped attachment section comprises a widened section that widens outwardly in the radial direction in a direction toward the circumferential free rim.

18. The filter housing according to claim 17, wherein the widened section is arranged, viewed in the axial direction, between the second at least part-circumferential axial stop surface and the circumferential free rim.

19. The filter housing according to claim 1, wherein the filter is a spin-on filter and the housing pot is comprised of sheet metal.

20. The filter housing according to claim 1, further comprising a housing cover, wherein the at least one filter-associated connecting element is provided on the housing cover, wherein the housing cover is connected by the securing ring to the housing pot.

21. The filter housing according to claim 20, wherein the securing ring comprises one or more fixation elements for fixation of the housing cover.

22. The filter housing according to claim 21, wherein the one or more fixation elements are bent tabs that engage behind the housing cover.

23. The filter housing according to claim 22, wherein the bent tabs are circumferentially distributed about the securing ring and the bent tabs each engage through a respective through opening of the housing cover.

24. The filter housing according to claim 20, wherein the securing ring comprises a bottom section and the housing cover is resting at least with sections thereof on the bottom section.

25. The filter housing according to claim 24, wherein the bottom section comprises at least one filter-associated projection that rises in the axial direction and is configured to support at least one corresponding connection-associated section of the connecting device.

26. An exchangeable filter of a filter device for liquids, the exchangeable filter device comprising at least one filter housing, therein the at least one filter housing comprises: a housing pot configured to accommodate at least one filter element; at least one filter-associated connecting element configured to be connected by a rotary and/or plug-in connection relative to a connecting axis to a connecting device of the filter device for connecting the exchangeable filter; a securing ring disposed at an end face of the filter housing and forming a cup-shaped attachment section, wherein, by a rotary and/or plug-in movement relative to the connecting axis, the cup-shaped attachment section is attachable to a corresponding insertion section of the connecting device; wherein the cup-shaped attachment section comprises a circumferential free rim at an open side of the cup-shaped attachment section and is connected at the circumferential free rim to a circumferential wall of the housing pot by a crimp connection; wherein the cup-shaped attachment section comprises a sealing receptacle of at least one circumferential sealing device that is configured to act sealingly at least radially in a radial direction relative to the connecting axis; wherein the sealing receptacle is open inwardly in the radial direction and comprises a radial sealing surface pointing inwardly in the radial direction and configured to support at least one annular seal; wherein the securing ring comprises a first at least part-circumferential axial stop surface for the at least one annular seal in an axial direction of the connecting axis; a stop ring inserted from the open side of the cup-shaped attachment section into the securing ring and providing a second at least part-circumferential axial stop surface for the at least one annular seal opposite the first at least part-circumferential axial stop surface in the axial direction.

27. A connecting device of a filter device for connecting an exchangeable filter for liquids, the connecting device comprising: at least one connecting element configured to connect relative to a connecting axis by a rotary and/or plug-in movement for connecting a filter; at least one part of a circumferential sealing device that is acting sealingly at least in a radial direction relative to the connecting axis; an end-face insertion section to which a cup-shaped attachment section of a filter housing of the filter is attachable by a rotary and/or plug-in movement relative to the connecting axis; wherein on the connecting element a first part of an anti-rotation securing device is arranged which corresponds to a second part of the anti-rotation securing device provided on the filter.

28. The connecting device according to claim 27, wherein the connecting element comprises an axial stop acting in the axial direction of the connecting axis and defining an end position of a corresponding at least one filter-associated connecting element.

29. The connecting device according to claim 27, wherein the first part of the anti-rotation securing device comprises an at least partially circumferentially extending groove that is open outwardly in the radial direction, wherein the groove is configured to lock a rim of an opening of a securing sleeve of the cup-shaped attachment section extending coaxially away from a housing cover of the filter.

30. The connecting device according to claim 29, wherein the connecting element is a central connecting socket comprising an outer thread, wherein the groove is present on a wall surface of the connecting socket.

31. The connecting device according to claim 30, wherein the connecting socket comprises on a side facing away from the filter a projecting shaft shoulder adjoining the groove and providing an axially acting stop for the securing sleeve of the filter.

32. The connecting device according to claim 30, wherein the connecting socket, beyond the groove in an insertion direction of the connecting socket, comprises an insertion ramp that tapers in a direction toward the filter.

33. A filter device for liquids, the filter device comprising: an exchangeable filter comprising at least one filter housing comprising a housing pot configured to accommodate at least one filter element; a connecting device comprising an insertion section and at least one connecting element; wherein the exchangeable filter comprises at least one connecting element connectable relative to a connecting axis by a rotary and/or plug-in movement to the at least one connecting element of the connecting device; wherein the at least one filter housing comprises at least a first part of at least one circumferential sealing device configured to act sealingly at least radially in a radial direction relative to the connecting axis and wherein the connecting device comprises at least a second part of the at least one circumferential sealing device; wherein the at least one filter housing comprises a securing ring disposed at an end face of the at least one filter housing and forming a cup-shaped attachment section, wherein, by the rotary and/or plug-in movement relative to the connecting axis, the cup-shaped attachment section is attachable to the insertion section of the connecting device; wherein the cup-shaped attachment section comprises a circumferential free rim at an open side of the cup-shaped attachment section and is connected at the circumferential free rim to a circumferential wall of the housing pot by a crimp connection; wherein the cup-shaped attachment section comprises a sealing receptacle forming the first part of the at least one circumferential sealing device, wherein the sealing receptacle is open inwardly in the radial direction and comprises a radial sealing surface pointing inwardly in the radial direction and configured to support at least one annular seal; wherein the securing ring comprises a first at least part-circumferential axial stop surface for the at least one annular seal in an axial direction of the connecting axis; wherein the at least one filter housing comprises a stop ring inserted from the open side of the cup-shaped attachment section into the securing ring and providing a second at least part-circumferential axial stop surface for the at least one annular seal in the axial direction; wherein on the at least one connecting element of the connecting device a first part of an anti-rotation securing device is arranged and wherein a second part of the anti-rotation securing device, configured to interact with the first part of the anti-rotation securing device, is provided on the exchangeable filter.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0103] Further advantages, features, and details of the invention result from the following description in which embodiments of the invention will be explained in more detail with the aid of the drawings. A person of skill in the art will consider the features disclosed in the drawing, the description, and the claims in combination expediently also individually and combine them to other meaningful combinations.

[0104] FIG. 1 shows schematically a longitudinal section of a filter system according to a first embodiment for motor oil of a motor oil circuit of an internal combustion engine, with an exchangeable filter which is exchangeably screwed onto a connecting device.

[0105] FIG. 2 is a schematic detail view of the filter system of FIG. 1 in the area of the connection of the exchangeable filter with the connecting device.

[0106] FIG. 3 is a schematic longitudinal section of a filter system according to a second embodiment.

[0107] FIG. 4 is a schematic isometric illustration of an exchangeable filter of a filter system according to a third embodiment.

[0108] FIG. 5 shows one half of a schematic longitudinal section of the filter system with the exchangeable filter of FIG. 4.

[0109] FIG. 6 is a schematic detail view of the longitudinal section of the filter system of FIG. 5 in the area of the connection of the exchangeable filter with a connecting device of the filter system.

[0110] FIG. 7 is an isometric illustration of an exchangeable filter of a filter system according to a fourth embodiment.

[0111] FIG. 8 is a plan view onto a connecting side of the exchangeable filter of FIG. 7.

[0112] FIG. 9 is a schematic longitudinal section of the exchangeable filter of FIGS. 7 and 8 along a section line IX-IX of FIG. 8.

[0113] FIG. 10 is a schematic detail view of the filter system with the exchangeable filter of FIGS. 7 to 9 in the area of the connection of the exchangeable filter with a connecting device of the filter system.

[0114] In the Figures, same components are provided with same reference characters.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0115] In FIG. 1, a filter system 10 according to a first embodiment for motor oil is shown in a longitudinal section. The filter system 10 is arranged in a motor oil circuit, not shown otherwise, of an internal combustion engine of a motor vehicle for filtration of the motor oil circulating therein.

[0116] The filter system 10 comprises a connecting device 12 with which a filter 14 is exchangeably connected. The connecting device 12 is connected fixedly with the internal combustion engine, for example, a frame of the internal combustion engine.

[0117] The filter 14 is designed as a so-called exchangeable filter. Such exchangeable filters are also known as so-called spin-on filters. The filter 14 comprises a filter housing 16 in which a filter element 18, designed in an exemplary fashion as a round filter element, is arranged so as to be non-exchangeable in the present embodiment. The filter housing 16 and the filter element 18 are coaxial to an axis 20.

[0118] When in the following radial, axial, coaxial, circumferential or the like is mentioned, this relates to axis 20, if nothing is indicated otherwise. In the present case, the axis 20 coincides with an element axis of the filter element 18, a filter axis of the filter 14, and a connecting axis of the filter 14 with the connecting device 12. For reasons of better clarity, in the following only the term axis 20 is used wherein, depending on the context, one or several of the aforementioned axes are meant. In other embodiments of the invention, at least two of the aforementioned axes can extend parallel or at a slant to each other.

[0119] The filter housing 16 comprises a housing pot 17. The housing pot 17, for example, is comprised of sheet metal. The housing pot 17 comprises at an end face which is facing the connecting device 12 an installation opening for the filter element 18. After the installation of the filter element 18, the installation opening is covered by a housing cover 22 of the filter housing 16.

[0120] The housing cover 22 comprises a coaxial connecting opening 24. The connecting opening 24 serves also as an outlet opening of the filter 14 for purified motor oil. The radial inner rim of the housing cover 22 which surrounds the connecting opening 24 comprises a coaxial inner thread 26.

[0121] Moreover, the housing cover 22 comprises a plurality of cover liquid passages 28 in the form of through openings which are realized as through bores, for example. The cover liquid passages 28 serve as inlet openings for the motor oil to be purified into the filter 14. The cover liquid passages 28 are located radially between the connecting opening 24 and the radial outer rim of the housing cover 22.

[0122] The housing cover 22 is secured by means of a coaxial securing ring 30, which is part of the filter housing 16, in the installation opening of the housing pot 17. A detail view of the filter system 10 in the area of the securing ring 30 is shown in FIG. 2.

[0123] The securing ring 30 is a formed part of sheet metal. The securing ring 30 comprises a coaxial cup-shaped attachment section in the form of a circumferential push-on section 32. The securing ring 30 is inserted into the installation opening of the housing pot 17 such that the open side of the push-on section 32 is pointing outwardly in axial direction. A circumferential wall of the push-on section 32 is contacting in this context the radial inner circumferential side of a circumferential wall 171 of the housing pot 17. The extension of the circumferential wall of the push-on section 32 corresponds to the extension of the circumferential wall 171 of the housing pot 17. The free rim of the circumferential wall of the push-on section 32 is connected by means of a crimp connection 34 with the free rim of the circumferential wall 171 of the housing pot 17.

[0124] At its radial inner circumferential side, the circumferential wall of the push-on section 32 forms a filter-associated radial sealing surface 36 for an annular seal 38. The filter-associated radial sealing surface 36 has a coaxial cylindrical extension. The annular seal 38 is designed as an O-ring seal. The annular seal 38 is elastic.

[0125] In a circumferential guide section 40, axial between the filter-associated radial sealing surface 36 and the free rim of the circumferential wall of the push-on section 32, the circumferential wall of the push-on section 32 and the section of the circumferential wall 171 of the housing pot 17 provided thereat widen approximately in a funnel shape outwardly in radial direction.

[0126] On its side which is axially facing the filter element 18, the circumferential wall of the push-on section 32 passes monolithically into a circumferentially and radially extending annular bottom section 42. With the bottom section 42, the securing ring 30 is resting against the facing side of the housing cover 22.

[0127] At its radial inner circumferential rim, the bottom section 42 has a plurality of holding tabs 44. The holding tabs 44 are arranged so as to be distributed circumferentially. Each holding tab 44 is correlated with one of the cover liquid passages 28. The holding tabs 44 are bent such that they engage the cover liquid passages 28. The housing cover 22 is secured by means of the holding tabs 44 on the securing ring 30. The securing ring 30 fixes the housing cover 22 on the filter housing 16.

[0128] Viewed radially, between the holding tabs 44 and the circumferential wall of the push-on section 32, a projection in the form of a circumferentially extending step 46 is formed on the bottom section 42. Viewed from the filter element 18, the step 46 rises in axial direction outwardly. In the area of the step 46, the housing cover 22 is provided with a corresponding projection.

[0129] In the following, the connecting device 12 is explained in more detail. The connecting device 12 comprises a base member 48 and a coaxial connecting socket 50. The base member 48 is comprised of plastic material, for example, produced by casting. The connecting socket 50 is comprised of metal.

[0130] The connecting socket 50 is embedded in the base member 48 with a section which is facing away from a side of the base member 48 that is facing the filter 14. On the side which is facing the filter 14, the connecting socket 50 projects axially out of the base member 48. The connecting socket 50 comprises a coaxial outer thread 52 on its radial outer circumferential side. The outer thread 52 forms with the inner thread 26 of the housing cover 22 a screw connection for attachment of the filter 14.

[0131] Axially between the outer thread 52 and the embedded area of the connecting socket 50, the latter has a step which provides an axial stop 53. The housing cover 22, when being screwed onto the connecting socket 50, is contacting the stop 53 in the end position of the filter 14.

[0132] The base member 48 comprises moreover mounting sections, which are not shown in the Figures, with which it can be attached to the frame part of the internal combustion engine, for example.

[0133] Moreover, the base member 48 comprises an inlet line, hidden in the Figures, for motor oil to be purified and an outlet line 54 for purified motor oil. The outlet line 54 passes across on the side of the connecting socket 50 facing the filter 14 and is formed here by the socket 50. The inlet line and the outlet line 54 serve as connecting lines. Outside of the base member 48, the inlet line and the outlet line 54 are connected respectively to the motor oil circuit.

[0134] On the side which is facing the filter 14, the base member 48 is embodied as an insertion section in the form of a plug-in section 56. In the plug-in section 56, the connecting socket 50 is arranged. The radial outer circumferential side of the plug-in section 56 is coaxial to axis 20. The radial outer circumferential side of the plug-in section 56 is stepped once inwardly in radial direction. It forms thereat a coaxial sealing receptacle 58 for the annular seal 38. The sealing receptacle 58 is open in radial outward direction and open axially toward the side of the plug-in section 56 which is facing the filter 14.

[0135] The sealing receptacle 58 is delimited in radial inward direction by a coaxial web 60. The web 60 extends in axial direction. The radial outer circumferential side of the web 60 forms a connection-associated radial sealing surface 62 for the annular seal 38. The connection-associated radial sealing surface 62 has a coaxial cylindrical shape. On the side facing the filter 14, the web 60 with the connection-associated radial sealing surface 62 projects past the annular seal 38 in axial direction.

[0136] In radial direction between the web 60 and the connecting socket 50, a coaxial annular depression 64 is arranged. The depression 64 is open in a direction toward the side of the plug-in section 56 which is facing the filter 14. The inlet line opens into the depression 64.

[0137] With the filter 14 mounted, the securing ring 30 is pushed with the push-on section 32 from the exterior onto the plug-in section 56, i.e., is attached. The axial extension of the radial inner circumferential side of the circumferential wall of the push-on section 32 as a whole is greater than the axial extension of the web 60. The filter-associated radial sealing surface 36, viewed axially, terminates with the sealing receptacle 58. The guide section 40 projects past the sealing receptacle 58 in axial direction. The free rim of the web 60 with its radial inner side can be supported radial outwardly on the step 46 of the securing ring 30 in radial direction.

[0138] A coaxial fluid space 66 is delimited radially between the connection-associated radial sealing surface 62 and the filter-associated radial sealing surface 36. The fluid space 66 is formed in an area of the sealing receptacle 58 which is not occupied by the annular seal 38. The fluid space 66 is connected by fluid connections, hidden in FIGS. 1 and 2, with the depression 64 and through the depression 64 is connected oil-conductingly with the inlet line.

[0139] Prior to mounting of the filter 14 on the connecting device 12, the annular seal 38 is placed from the side of the base member 48 facing the filter 14 into the sealing receptacle 58 of the plug-in section 56.

[0140] Subsequently, the filter 14, with the push-on section 32 leading, is first pushed with a push-on movement axial to the axis 20, i.e., axial to the connecting axis, onto the plug-in section 56. The guide section 40 serves in this context as a centering aid.

[0141] Upon pushing on the push-on section 32, the connecting socket 50 is guided to the connecting opening 24 of the housing cover 22. By means of a subsequent screwing movement, which constitutes a combined rotary and plug-in movement about the connecting axis 20, the filter 14 is screwed onto the connecting socket 50.

[0142] The guide section 40 serves as a mounting and centering aid during push-on and subsequent screwing movement. The annular seal 38 can axially glide along the radial inner circumferential side of the guide section 40 and can be guided into the area of the filter-associated radial sealing surface 36.

[0143] In the end position of the filter 14, the housing cover 22 contacts axially the stop 53 so that a further screwing movement is prevented. The stop 53 defines the axial end position of the filter 14.

[0144] In the end position of the filter 14, the annular seal 38 with its radial inner circumferential side is resting on the connection-side radial sealing surface 62 and with its radial outer circumferential side on the filter-associated radial sealing surface 36 so as to act sealingly in radial direction, respectively. The filter-associated radial sealing surface 36, the connection-associated radial sealing surface 62, and the annular seal 38 form a circumferential sealing device 76 which is acting sealingly relative to the environment in radial direction relative to the axis 20. The annular seal 38 enables due to its radial sealing action in connection with the axial extension of the filter-associated radial sealing surface 36 and the connection-associated radial sealing surface 62 an axial position tolerance beyond its function as annular seal. The sealing receptacle 58 and thus the fluid space 66 are delimited on the side which is facing the filter 14 by the bottom section 42 of the securing ring 30.

[0145] In operation of the internal combustion engine, motor oil from the motor oil circuit is conveyed for filtration through the inlet line first into the depression 64. Due to the fluid connection with the fluid space 66, the latter is loaded with oil pressure. The oil pressure in the fluid space 66 effects an axial compression of the annular seal 38. In this context, the annular seal 38 can be supported axially against the sidewall 67 of the sealing receptacle 58 which is axially opposite the bottom section 42. The sidewall 67 serves as a stop or stop area for the annular seal 38. The annular seal 38 yields elastically in response to the oil pressure in radial direction outwardly and inwardly and is thus more strongly pressed against the corresponding radial sealing surfaces 36 and 62. In this way, the radial sealing action of the annular seal 38 is augmented in operation. In this context, the web 60 can be supported with its free rim on the radial inner circumferential side of the step 46 and can thus form a counter bearing.

[0146] The motor oil to be purified passes from the depression 64 through the cover liquid passages 28 into an annular space 68 of the filter housing 16 surrounding the filter element 18.

[0147] The motor oil to be purified flows through a filter medium 70 of the filter element 18, indicated in FIG. 1 by arrows 72, in radial direction from the exterior to the interior, is purified therein, and reaches then an element interior 74 of the filter element 18.

[0148] From the element interior 74, the purified motor oil flows through the connecting opening 24, respectively, the connecting socket 50, into the outlet line 54. Through the outlet line 54, the purified motor oil is returned from the filter system 10 back into the motor oil circuit.

[0149] In FIG. 3, a filter system 10 according to a second embodiment is illustrated. Those elements that are similar to those of the first embodiment of FIGS. 1 and 2 are provided with the same reference characters. The second embodiment differs from the first embodiment in that a filter-associated sealing receptacle 158 is provided instead of the connection-associated sealing receptacle 58. The annular seal 38 is secured on the filter in the sealing receptacle 158.

[0150] A sidewall 167 that forms a first filter-associated axial stop section is realized by a corresponding step of the securing ring 30.

[0151] The second filter-associated axial stop section 178 on the side of the sealing receptacle 158 which is opposite the sidewall 167 is realized by a coaxial stop ring 180. The stop ring 180 can be comprised, for example, of metal or plastic material. The stop ring 180 comprises on its radial outer circumferential side a plurality of locking hooks 182. The locking hooks 182 engage radial outwardly the crimp connection 34. With the locking hooks 182, the stop ring 180 is detachably secured axial outwardly on the free rim of the housing pot 17.

[0152] When the filter 14 is mounted, the stop ring 180 is contacting axially an area of the base member 48 which is radial outwardly surrounding the plug-in section 56. When the filter 14 is separated from the connecting device 12, the stop ring 180 with the second filter-associated stop section 178 secures the annular seal 38 in the sealing receptacle 158.

[0153] Instead of the filter-associated guide section 40 of the first embodiment, a connection-associated guide section 140 is provided in the second embodiment. The connection-associated guide section 140 is in the form of a bevel on the radial outer side of the free rim of the web 60. The filter-associated stop ring 180 and the annular seal 38 are guided along the guide section 140 upon attachment of the filter 14.

[0154] In FIGS. 4 to 6, a filter system 10 according to a third embodiment is illustrated. Those elements that are similar to those of the second embodiment of FIG. 3 are provided with the same reference characters. The third embodiment differs from the second embodiment in that from the end of the free rim 33 of the attachment section 32 a stop ring 180 is inserted into the securing ring 30. The stop ring 180 provides a second filter-associated axial stop section with a second circumferential axial stop surface 178 for the annular seal 38.

[0155] The securing ring 30, as illustrated in FIG. 6 in detail, is formed to follow closely with a predetermined axial extension the circumferential wall 171 of the housing pot 17 in a first section 35a that is near the free rim 33 of the attachment section 32. The securing ring 30 comprises a substantially cylindrical cross section in the first section 35a. The securing ring 30 comprises a reduced diameter section 300 in a second section 35b which is facing away from the free rim 33. The reduced diameter section 300 forms the first circumferential axial stop surface 167 for the annular seal 38.

[0156] The stop ring 180 is pressed from the end of the end face 161 of the filter housing 16 into the securing ring 30. The stop ring 180 has a substantially Z-shaped cross section. A leg of the Z extending perpendicular to the connecting axis 20 forms the second stop surface 178 for the annular seal 38. The leg is in an axial position where, in radial direction externally, the crimp connection 34 is present. The stop ring 180 does not project in axial direction father into the securing ring 30 than the crimp connection 34 is extending in axial direction away from the free rim 33.

[0157] The crimp connection 34 comprises a crimp that is bent in radial direction outwardly. The crimp does not generate a cross section restriction on the free rim 33 in relation to the circumferential wall 171 of the housing pot 17.

[0158] In FIGS. 7 to 10, a filter system 10 according to a fourth embodiment is shown. Those elements which are similar to those of the third embodiment of FIGS. 4 to 6 are provided with the same reference characters. The fourth embodiment differs from the third embodiment in that the filter housing 16 has a securing sleeve 80 at its open end face 161.

[0159] The securing sleeve 80 is arranged coaxially in the attachment section 32. The securing sleeve 80 has a central opening 801. The opening 801 is positioned in an end face 802 of the securing sleeve 80. The opening 801 is designed to receive in a mounting state the connecting socket 50 of the connecting device 12 of the filter device 10.

[0160] The securing sleeve 80 is resilient at least in axial direction. The securing sleeve 80 is comprised of a resilient material, for example, a thin-walled sheet metal. The securing sleeve 80 has a geometry that favors resilient properties. The securing sleeve 88 is monolithically formed in the securing ring 30 as a coaxial bulge of the securing ring 30.

[0161] The securing sleeve 80 extends in axial direction up to the level of a circumferential free rim 33 of the attachment section 32. The securing sleeve 80 ends at the same level as the rim 33 of the attachment section 32.

[0162] The rim of the securing sleeve 80 which delimits the opening 801 forms a part of an anti-rotation securing device 410. Another part of the anti-rotation securing device 410 in the form of a groove 501 is positioned at the connecting socket 50 of the connecting device 12. The groove 501 of the anti-rotation securing device 410 correlated with the connecting device 12 is arranged on the wall surface of the connecting socket 50 so as to be continuously outwardly open in the radial direction. The groove 501 and the rims of the opening 801 of the securing sleeve 80 correspond with each other for realization of the anti-rotation securing device 410. In the groove 501, the rim of the opening 801 of the securing sleeve 80 can be locked.

[0163] Beyond the groove 501 in the insertion direction, the connecting socket 50 has an insertion ramp 503 which tapers in the direction toward the filter 14.

[0164] On a side which is facing away from the filter 14, the connecting socket 50 comprises, adjoining the groove 501, a projecting shaft shoulder 502. The shaft shoulder 502 constitutes an axially acting stop 153 for the securing sleeve 80 of the filter 14 (a similar stop is also illustrated in the embodiment of FIG. 1 at reference character 53).

[0165] While specific embodiments of the invention have been shown and described in detail to illustrate the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles.