Field of the invention

The invention relates to a fluid filter cartridge for being removably inserted into a fluid filter housing with a housing socket and a housing cover. The filter cartridge has a filter element forming a fluid channel, a front end and a rear end. A con- nector element is attached to the front end, wherein the connector element has at least a forward-facing side facing away from the front end into a forward di- rection and a peripheral surface. The peripheral surface has at least one radially protruding segment. A first fluid port in the forward-facing side is fluid communi- cation with a first fluid opening in the radially outward facing surface of the filter cartridge. A second fluid port is in fluid communication with the fluid channel. A gasket is supported on a first and/or second ring surface of the peripheral sur- face.

Description of the related art Filter cartridges are presently used in numerous applications to filter fluids being used in any kind of machinery, typical examples of these fluids are air, oil and water. If a filter is clogged or reaches a service interval the filter housing can be opened, typically by removing the housing cover from the housing socket. Next, the filter cartridge can be removed and a new filter cartridge can be inserted prior to closing the housing again. Often, the housing cover is threaded to the housing socket, which requires mostly less space and is easier to handle than some sort of elastic caging pushing the housing cover to the socket. In many ap- plications, however, the filter housing is subjected to vibrations and at the same time pressure fluctuations of the fluid to be filtered. This combination may lead to the situation that the housing cover unintendedly unthreads, which may lead to catastrophic engine failures. For example, consider a sudden oil pressure of a combustion engine under full load being the consequence of an unintendedly opening the combustion engine's oil filter housing during.

EP 1870 152 A relates to a flow optimized filter for pressurized gas having in in- let channel and an outlet channel which contain an upper filter part, and a hol- low cylindrical filter element having lower filter part. The upper filter part has housing and an insert, in which the course of the inlet and outlet channels is op- timized. The insert is rotatably supported and exchangeable within the housing.

DE 10309428 A1 suggests a gas filter with a housing top and a housing bottom.

In between of these is a rotatable connecting flange. A rotation of the flange al- lows to convert the filter from a coalescence filter for removing condensate into a dust filter and vice versa.

GB 2,158,364A addresses the problem of providing a large diameter pipeline strainer that combines the advantages of increased filter area, easy cleaning, and low pressure drop as known for basket type strainers with the advantages of Y- type strainers being smaller in size and less expensive. The suggested pipeline strainer comprised a body having a chamber, an inlet to said chamber and an outlet from said chamber. The inlet and the outlet are coaxial and define a longi- tudinal axis. The body has a lateral opening at said chamber, a removable cover for sealing said lateral opening, and a strainer member mounted in said chamber and being removable through said lateral opening.

WO 2020/201480 A1 relates to a to a filter with a filter housing having two filter housing parts. A filter insert is replaceables arranged in the second filter housing part. The filter insert has a filter material body and two end panels. An annular seal support supports a seal that is movably guided on the filter insert in an axi- ally limited manner relative to the end panel. The seal support simultaneously forms or has the valve element of a valve. The end panel faces the joint between the filter housing parts forms the valve seat and a medium passage is selectively released or blocked by means of the valve.

EP 2 373 398 A1 relates to an air filter with a housing comprising a socket and a cover enclosing a volume in which a replaceable filter cartridge is positioned. The filter cartridge comprises an essentially cylindrical filter element with a fluid channel. On top of the filter element is a connector for connecting the filter ele- ment with the socket. The connector has a first port being in fluid communica- tion with an air outlet of the socket. The air enters the filter cartridge via a first port and passes through a conduit of the connector to a slot in the peripheral surface of the filter cartridge. Subsequently, the air passes the filter element, en- ters the fluid channel and from there flows via a second conduit of the connector to an air inlet of the socket. The connector and the upper end of the housing cover jointly engage into a recess of the socket, wherein a collar of the connector is located in between of the socket facing surface of the tubular housing cover and the bottom of the complementary recess. The housing cover facing surface of the collar is inclined and supports a gasket. When closing the cover by thread- ing the housing cover onto the housing socket, the gasket is compressed in a cor- ner being delimited by the inclined surface of the collar, the radially inward fac- ing surface of the socket's recess the socket facing end of the housing cover.

Summary of the invention

The problem to be solved by the invention is to ensure that the filter housing cover of a fluid filter system remains fully closed during operation of the filter system.

A solution of this problem is provided by filter cartridge of claim 1. The depend- ent claims relate to further improvements of the invention. The filter cartridge is configured to be removably inserted into a filter housing with a housing socket and a housing cover. In most applications the housing cover and the socket have complementary screw threads allowing to screw the housing cover to the socket. As initially explained, the housing cover may be threaded onto the housing socket when installing the filter cartridge. The filter cartridge can even be retrofitted into a huge number of existing filter housings.

The filter cartridge has filter element with a fluid channel. As usual the fluid channel defines a longitudinal axis, which in most applications coincides with the filter axis. Further, the filter element has a front end and a rear end. The filter el- ement can be made of plied filter paper, cloth, filter foam or the like.

A connector element, as well briefly referred to as "connector", may be attached to the front end. For example, the front end of the filter element may have a front end cap to which the connector may be attached. Of course, the filter ele- ment may as well comprise a rear end cap at its rear end. The front-end cap and the connector may as well be unitary, i.e. be a single part. The connector has a forward-facing side facing away from the front end of the filter element into a forward direction. This forward direction is typically but not necessarily parallel to the longitudinal axis. Deviations from perfect parallelism can be accepted, be they intended or unintended. Only for conceptual simplicity, we assume that the forward direction is parallel within an angle to the longitudinal axis, wherein is an error margin and may be e.g. one of 30°, 20°, 15°, 10°, 5°, 1.5°, 1°, 0.5° or 0°. Thus at least essentially parallel means wherein A = {30°, 20°, 15°, 10°, 5°, 1.5°, 1°, 0.5°, 0°} and an angle a is considered to be within Further, the connector has rearward-facing side. The rearward side faces in the opposite direction compared to the forward-fac- ing side and hence towards the filter element's front end. Thus, the rearward di- rection is opposed to the forward direction. Again, deviations within can be accepted. Further, the connector has a peripheral surface. The peripheral surface typically (but not necessarily) connects the forward-facing side and the rearward facing side, thus it may span from a forward edge to a rearward edge being formed by the peripheral surface and the forward -facing side or the rearward facing side, respectively. In practice these forward edge as well as the rearward edge may be rounded or other forms of a smooth transition may be realized. Preferably, the peripheral surface is a ring surface, particularly preferred it is a rotationally invar- iant ring surface being rotationally invariant under a rotation around the longitu- dinal axis. The rotational symmetry may as well be broken, e.g. because only dis- crete rotations (e.g. by rotations by {2, 3, 4, 5, ... , N} and N being an inte- ger, e.g. 1000) project the peripheral surface onto itself. In another example, the peripheral surface may not be rotationally invariant but mirror symmetric, e.g. relative to the longitudinal axis (mirror axis) and or/or at least one mirror plane comprising the longitudinal axis. The peripheral surface may preferably comprise at least one protruding segment. The protruding segment may be gasket and/or a wedge element facing surface delimiting a face of a protrusion of the connector, which protrusion extends (e.g., radially) outwards. The protruding segment may be a (preferably inclined) surface facing towards the wedge element. Thus, the protruding segment may as well form a step as will be explained with reference to the Figures. Radially out- wards means in this example that radius of the peripheral surface in the area of the protruding segment is larger than the radius of the first and/or second ring surfaces.

The filter cartridge may further comprise a first fluid port in the forward-facing side. This first fluid port may be in fluid communication with a first fluid opening in the radially outward facing surface of the filter cartridge. The radially outward facing surface of the filter cartridge is essentially the peripheral surface of the fil- ter cartridge. Only to avoid ambiguities, i.e. to verbally distinguish the peripheral surface of the connector from the peripheral surface of the filter cartridge, the peripheral surface of the filter cartridge is referenced to as radially outward fac- ing surface of the filter cartridge.

For example, an optional first conduit may fluidly connect the first fluid port and the first fluid opening thereby setting them in fluid communication. The optional first conduit may be provided by the connector.

Preferably, a second fluid port of the filter cartridge is in fluid communication with the fluid channel. The fluid communication may as well be established via an optional second conduit connecting the second port and a second fluid open- ing. Again, the optional second conduit may be provided by the connector, but as will explained below and with reference to the Figures the optional second con- duit can be omitted, if the socket is adapted to connect directly to the fluid chan- nel, e.g. via a through hole in a front-end cap.

A gasket may be movably supported on a first and/or second ring surface of the peripheral surface of the connector. Accordingly, the gasket is configured to be shifted parallel to the axial direction, thereby sliding over the first and/or second ring surface.

The gasket may be configured to seal a gap between a filter housing surrounding the first and/or second ring surface of the peripheral surface of the connector and the filter cartridge. For example, the gasket may be configured to seal a gap between a filter housing surrounding the first and/or second ring surface of the peripheral surface of the connector and the first and/or second ring surface of the peripheral surface of the connector. Thus, in operation, the gasket may seal a gap between the housing and the filter cartridge, to thereby prevent the filter from spilling. In a preferred example, the position of the gasket on the first and/or second ring surface of the peripheral surface of the connector is between the rear end facing boundary of the first fluid opening and the front end of the filter cartridge. In other words the first and/or second ring surface of the peripheral surface of the connector element is preferably between the first fluid opening and the front end of the filter cartridge. It is noted that a portion of the gasket may even ex- tend over or into the first fluid opening as will be apparent from the figures.

Thus, in operation, the pressure of the fluid being filtered may push the gasket axially towards the front end. In other words, the pressure drop between the for- ward facing side and the rearward facing side of the gasket results in a force in the forward direction, i.e. towards the forward end of the filter cartridge.

Thus, a fluid to be filtered may flow from the first fluid port, which may be lo- cated in the forward-facing side of the connector, through a first conduit to the first fluid opening in the radially outward facing surface of the filter cartridge and hence from there to the peripheral surface of the filter element. The fluid may then pass the filter element, e.g. radially inwards, enter the fluid channel and may be removed via the second fluid port from the fluid channel. The second fluid port may be provided by an end cap of the filter element or as well by the connector. The second fluid port may thus be fluidly connected via a second con- duit with the fluid channel. The flow direction of the fluid can of course be re- versed, but the described flow direction from the first port via the first conduit to and via the filter element into the fluid channel and from there to the first port is preferred.

In a preferred example, the filter cartridge further comprises at least one op- tional wedge element being movably supported on the peripheral surface in be- tween of the gasket and the protruding segment. The wedge element may have a first wedge surface and a second wedge surface. The first wedge surface may face towards the protruding segment and/or the second wedge surface may face away from the peripheral surface. The wedge element may further comprise a back side connecting the first wedge surface and the second wedge surface. The back side of the wedge element may thus face away from the protruding seg- ment.

The at least one wedge element may be movably supported to be moved in a first direction from a first position into a second position by exerting a force par- allel to the longitudinal axis to the back side. For example, the first direction may be a superposition of the forward direction and the radial direction. In another example, the first direction may be a superposition of the rearward direction and the radial direction. In any case, the first wedge surface may be (preferably di- rectly) adjacent to the protruding segment, but other means may be located in between. Relevant is only that the protruding segment provides an at least indi- rect abutment on which the first wedge element slides in the first direction.

The at least one wedge element, at least if in its first position, may be positioned in between of the gasket and the protruding segment. This sequence is herein re- ferred to asl "alternative I". In a second example, the gasket and the wedge ele- ment are located at opposite sides of the protruding segment, i.e. the protrusion may as well be in between of the gasket and the wedge element. This second ex- ample is herein referred to as "alternative II".

The protruding segment may have a plain bearing surface on which the wedge element is movably supported to slide on its first wedge surface in the first direc- tion if a force with an axial component facing toward the protruding segment is exerted to the back side of the wedge element. In the example of alternative I this force may be directed in the forward direction and in the example of alterna- tive II the force may point in the rearward direction.

As apparent from the above the wedge element may be forced in the first direc- tion thereby being radially supported by the protruding segment. If mounted, in the filter housing the second wedge surface abuts the inner surface of the hous- ing cover (if it has been forced accordingly) and thereby establishes a force fit be- tween the filter cartridge and the housing cover. Thus, almost any housing cover can be prevented from accidentally opening during operation by retrofitting the filter cartridge. In operation, i.e. once a fluid pressure is provided, in alternative I the pressure drop between the rear and the forward side of the gasket 80 pro- vides a force that pushes the gasket against the back side of the wedge element and thereby provides a force shifting the wedge in the first (i.e. forward) direc- tion. In alternative II, the pressure drop provides a force that pushes the gasket against the protrusion and hence shifts the protruding segment against the wedge element, leading to the same result. In both alternatives, the wedge ele- ment moves relative to the filter cartridge in the first direction and establishes the force fit which prevents the housing cover form inadvertently rotating.

Preferably, if in the first position, the wedge element does not radially protrude over the protruding segment, whereas if in the second position, the wedge ele- ment preferably radially protrudes over the protruding segment in the radial di- rection. This eases a simple installation of the filter cartridge in the filter housing.

In a preferred example, the at least one wedge element is a ring segment. The at least one wedge element may as well comprise or be attached to a ring segment.

Preferably the ring segment at least partially encircles the peripheral surface.

This measure increased reliability of the force fit and further enables to distrib- ute the force evenly around the peripheral surface.

For example, the ring segment may be an initially closed ring a with weak link be- ing configured to break if the wedge element is moved from the first position in the first direction towards the second position, thereby allowing the ring seg- ment to increase its radius while being shifted. At the same time, the weak link ensures that the wedge remains in its first position during installation of the filter cartridge.

The increase in radius may as well be provided for by use of an elastic wedge ele- ment and/or use of an open ring as wedge element. Other possibilities to config- ure the wedge element and/or the ring segment to radially expand during a movement of the wedge element from its first position into its second position can be used as well.

Preferably, the absolute value of a quotient q being defined as q = decreases in the case of alternative I and increases in the case of alternative II with increasing axial distances of the protruding segment from the gasket front end wherein r ₄ (d) is the radius of the inclined surface at the distance d. This shape of the protruding segment provides for a swift initial force fit, while increasing the clamping force between the filter cartridge and the housing per shifted distance, the further the wedge element is shifted in the first direction. Thereby, the wedge element sits particularly reliable in the gap between the housing cover and the protruding segment.

For example, the first wedge surface and/or the portion of the protruding seg- ment facing the first wedge surface (71) may each have/has at least one protru- sion with an edge and/or crest extending at least essentially parallel to the first direction or least essentially parallel to the axial direction along the inclined sur- face and/or along the first wedge surface and/or along the second wedge sur- face, respectively. At least essentially parallel intends to express that parallel is preferred, but deviations can be accepted. For example, deviations within {30°, 20°, 15°, 10°, 5°, 2.5°, 1°, 0°} can be accepted. The crests may alternatively be helical, configured to force the wedge element against the pro- truding segment in case the wedge element rotates relative to the connector and/or the housing cover. These protrusions allow for shifting the wedge element in the first direction while at the same time block and/or prevent a rota- tion of the wedge element relative to the connector or relative to the housing cover. Each of these measures further contributes to prevent the housing cover from coming loose.

Optionally, the gasket may be attached to the wedge element. This eases assem- bly of the filter cartridges while at the same time increases the reliability of the locking mechanism preventing the housing cover from coming loose.

In preferred example, the radial span Δr _g of the uncompressed gasket is greater than the radial span Δr _w of the wedge element. The wedge thus fits easily into the gap between the housing cover and the peripheral surface while the gasket reliably seals the gap between the peripheral surface and the housing cover.

Only to redraft it in other words, the gasket may abut and hence entrain the wedge element from the wedge's first position at least essentially parallel to the longitudinal direction if the gasket is sled or shifted from the first gasket position into the second gasket position, e.g. by the pressure gradient between the back side of the wedge element facing surface of the gasket and the opposed surface of the gasket (facing away from the back side, e.g. in the rearward direction). Similarly, in case of the alternative II, the gasket may be shifted until into its sec- ond gasket position. Once this second position is reached, the fluid pressure on the gasket and the rearward-facing side of the connector shifts the filter car- tridge onto the wedge element thereby shifting the wedge element in the first direction, relative to the filter cartridge. In this alternative II the first direction may be a superposition of the radial direction and the rearward direction.

The first ring surface and the second ring surface are preferably located in be- tween of the first fluid outlet and the protruding element, wherein the first ring surface may be closer to the first fluid outlet as the second ring surface. The first ring surface and the second ring surfaces may further jointly provide a plain bearing surface onto which the gasket can slide from a first gasket position on the first ring surface to a second gasket position on the second ring surface. By selecting the radii of the first and second ring surfaces the radius of the (uncom- pressed) gasket may be altered. For example, if the first ring surface has a smaller diameter than the second ring surface the inner radius of the gasket can be increased by shifting the gasket from the first ring surface to the second ring surface. This allows to reduce the initial breakaway force required for shifting the gasket from an initial retracted into a final extended position and hence provides an increase in reliability. If is the radius of the first ring surface, d ₁ denotes the axial distance of a point on the first ring surface to the front end, denote the minimum axial distance and the maximum axial distance of the first ring sur- face to the front end of the peripheral surface, respectively, denotes the radius of the first ring surface, d ₂ denotes the axial distance of a point on the second ring surface to the front end, and denote the minimum axial distance and the maximum axial distance of the second surface to the front end front end of the peripheral surface, respectively, then it is pre- ferred if [ ] is observed, wherein are the respective azimuthal angles of the points. Further it is preferred if wherein c ₁ is a constant and and/or ( ) wherein c ₂ is a constant and and/or at any given angle wherein B =

{0.10, 0.05, 0.025, 0.01, 0}. These measures each contribute to a decrease of the breakaway force of the gasket as well as to reliable seal of the gap between the peripheral surface and the housing cover.

The protruding segment may have a radius wherein d ₄ denotes the axial distance to the front end, denote the minimum axial dis- tance and the maximum axial distance of the protruding segment to the front end of the peripheral surface. Preferably the relation holds, wherein for any given angle for which the at least one inclined surface exists. This ensures that the force providing the force fit is evenly distributed. The gasket, if positioned on the second ring surface may preferably protrude ra- dially over the wedge element in its first position and/or in its second position to thereby ensure that the gap between the peripheral surface and the housing cover is sealed tightly.

In another example, the filter housing encloses the filter cartridge. The filter housing comprises at least a housing socket and the removable housing cover.

The housing cover may have a proximal end with a first thread and the housing socket may have a second thread being releasably engaged (or configured for be- ing releasably engaged) into the first thread thereby enclosing a volume config- ured for receiving the filter cartridge. The housing cover may further comprise an inwardly facing ring surface being radially opposed to the peripheral surface. The radius r _h of the inward facing surface is preferably greater than the maximum ra- dius of the protruding segment and smaller than the sum of the maximum radius of the protruding segment and the radial span of the wedge ele- ment, i.e. Herein the term wedge element has been used to imply that the wedge element is preferably configured to be clamped in between of the connector and the housing cover. The wedge element does not necessarily require to have the typi- cal shape of a wedge being typically considered to have a triangular cross sec- tion. As will be apparent from the description of the figures below, the wedge el- ement can have almost any shape, that forces the wedge element outwards (e.g. in the first direction) when a force parallel to the longitudinal axis is applied to the back side of the wedge element, the protruding segment of the peripheral surface being abutted in operation by the wedge element and the wedge ele- ment are hence configured to jointly provide for a movement of the wedge ele- ment in the first direction, if a force is applied to the back side of the wedge, wherein the back side of the wedge faces away from the protruding segment. Description of Drawings

In the following the invention will be described by way of example, without limi- tation of the general inventive concept, on examples of embodiment with refer- ence to the drawings.

Figure 1 shows an example filter cartridge in an example filter housing. Figure 2 shows a detail of the filter cartridge of Fig. 1 prior to be mounted.

Figure 3 shows a detail of the filter cartridge of Fig. 1 after being mounted.

Figure 4 shows a detail of the filter cartridge of Fig. 1 in operation.

Figure 5 shows a detail of another example filter cartridge prior to be mounted. Figure 6 shows the detail of Fig. 5 in operation. Figure 7 shows a detail of another example filter cartridge prior to be mounted. Figure 8 shows the detail of Fig. 7 in operation.

Figure 9 shows a detail of another example filter cartridge prior to be mounted.

Figure 10 shows the detail of Fig. 9 in operation.

Figure 11 shows a detail of another example filter cartridge. Figure 12 shows another example filter cartridge in another example filter hous- ing. Figure 13 shows a detail of Fig. 12.

In Fig. 1 a first embodiment of a filter cartridge 1 is shown. The filter cartridge 1 is located inside a filter housing with a socket 10 and a housing cover 20. As can be seen, the housing cover 20 is connected by a threaded connection to the housing socket 10. The filter housing has a sealing surface 25 facing inwards, preferably radially inwards towards the longitudinal axis 2 of the filter car- tridge 1.

The filter cartridge 1 has a connector element 50, as well briefly "connector 50", for fluidly connecting a filter element 30 of the filter cartridge 1 into a fluid flow. The filter element 30 may define a fluid channel 37 with a longitudinal axis 2. In operation, a fluid (e.g. an oil) may enter the filter cartridge 1 via a first fluid port 51 of the connector 50, flow through a first conduit 56 to a first fluid open- ing 58 in the peripheral surface of the filter cartridge 1. In the depicted example, the first fluid opening 51 is a slot being formed in between of a rearward-facing side 54 of the connector 50 and a front-end cap 33 of the filter element 30. But this location is only a preferred example. In other examples the boundary of the first fluid opening 58 may be entirely defined by the connector 50 or alterna- tively by the front-end cap 33 or even by some other part of the cartridge 1. In any case, the fluid may leave the filter cartridge 1 via the first fluid opening 58 and enter a gap 85 being provided between the housing cover 20 and the filter element 30. From there, the fluid may pass the filter element 30 and enter into the fluid channel 37. The fluid may be removed from the fluid channel 37 via a second fluid port 52, which may, e.g., be formed by the optional front-end cap 33 (see Fig. 11). Alternatively, as shown in the depicted example, filtered fluid may be removed through a second fluid opening 59 in the connector 50. The optional second fluid opening 59 is in fluid communication with an optional second fluid port 52 via an optional second conduit 57. The second fluid port 52 may preferably be coupled to a filtered fluid inlet of the filter housing. A gasket 80 may be located between a peripheral surface 60 of the connector 50 and the sealing surface 25 of the housing, to thereby separate the gap 85 in a forward portion and a rearward portion. This separation disables a fluid flow from the rearward portion into the forward portion of the gap 85 which fluid flow would lead to leakage of the (e.g. oil or gas or fuel, etc.) filter housing. The gasket 80 thus seals the forward portion from the rearward portion of the gap 85.

Fig. 2 shows a detail of the filter cartridge 1 prior to or during installation of the filter cartridge 1. As can be seen, the connector 50 has a forward-facing sur- face 53 and a rearward-facing surface 54 at its opposite end. The forward-facing surface 53 and the rearward-facing surface 54 may be connected by the periph- eral surface 60. The peripheral surface 60 may preferably have a first ring sur- face 61 and a second ring surface 62 (see as well Fig. 3). These first and second ring surfaces 61, 62 may be centered around the longitudinal axis 2 (c.f. Fig. 1). Herein, we assume the ring surfaces 61, 62 to be rotationally invariant under a rotation around the axis 2, but this constraint can be released and is only for con- ceptual simplicity.

As can be seen in Fig. 2, the radius of the first ring surface 61 may be smaller than the radius of the second ring surface 62 (for any azimuthal angle). But it is emphasized that this choice of relation is only an example. They may as well have the same radius. It is less preferred, but still possible that the radius of the first ring surface 61 is greater than the radius of the second ring surface 62.

Further, as shown, an optional intermediate ring surface 63 may connect the first ring surface 61 and the second ring surface 62. Alternatively, the first ring sur- face 61 and the second ring surface 62 may be immediately adjacent to each other. In Fig. 2, the gasket 80 is located in its first axial gasket position on the first ring surface 61. This is the intended position of the gasket 80 prior to inserting the fil- ter cartridge 1 into the filter housing. In this preferred example, the gasket 80 has a central portion 83 being located on the first ring surface 61 and two op- tional legs 81, 82 which may extend at least essentially in the rearward direc- tion 4. The first leg 81 may extend over the first fluid opening 58 and hence par- tially closes the first fluid opening 58. In between of the first leg 81 and the sec- ond leg 82 is an optional groove. The bottom of the groove may be delimited as shown by the central portion 83. The peripheral surface 60 may have a protrusion 65 with protruding segment 64 facing towards a wedge element 70. Only to avoid ambiguities, in all figures, the protruding segment 64 is considered as a surface segment of the peripheral sur- face 60.

In this example the wedge element 70 is located in between of the gasket 80 and the protruding segment 64, which has been referenced to above as alternative I.

The wedge element 70 may have a first wedge surface 71, a second wedge sur- face 72 and a back side. The back side 73 faces towards the gasket 80. The first wedge surface 71 faces towards the protruding segment 64 and the second wedge surface 72 faces outwards. The second wedge surface 72 has optional crests 721 which extend essentially the parallel to the axis 2. The wedge ele- ment 70 is hence configured to slide in a first direction 5 if a force is applied to its back side 73.

In the assembled state, being shown in Fig. 3, the gasket 80 has been shifted by a pusher 90 towards the wedge element 70. The second leg 82 of the gasket 80 is shown to extend into the housing, which shall only symbolize that the gasket 80 seals the gap 85 tightly. In practice, the second leg 82 of course contacts the inner surface of the housing cover 20. The corresponding portion of the housing cover's surface is referenced to by the numeral 25.

In operation, the liquid pressure forces the gasket 80 parallel to the longitudinal axis 2, until the wedge element 70 facing side of the gasket 80 abuts the wedge element 70 as shown in Fig. 4. The gasket 80, being pushed against the wedge el- ement 70 entrains the wedge element 70 parallel to the longitudinal axis 2. Due to the shape of the first wedge surface 71, the wedge element 70 is as well shifted radially outwards, what results in a movement of the wedge element 70 in the first direction 5 being a superposition of the radial direction and the for- ward direction 3. As a result of this process the wedge element 70 provides a force fitting connection between the housing cover 20 and the filter cartridge 1, thereby securing the housing cover 20 in place. Optional crests 75 engage into the corresponding sealing surface 25 of the housing cover 20.

Another example is shown in Fig. 5 and 6: Fig. 5 and 6 each show a detail similar to the detail of the filter cartridge 1 in Fig. 2 and description of Fig. 1 to 4 can be read on Fig. 5 and Fig. 6 as well. Fig. 5 shows the detail of the filter cartridge 1 prior to mounting and Fig. 6 shows the essentially the same detail assuming it would be in operation. To better show the filter cartridge 1 the housing cover 20 and the housing socket 10 are not shown. Like in the example of Fig. 1 to 4, the filter cartridge 1 has a wedge element 70. The only difference is the cross sec- tional shape of the wedge element 70: Again the wedge element 70 has a first wedge surface 71, a second wedge surface 72 and a back side 73. Still like in Fig. 1 and 2 the back side 73 faces towards the gasket 80 and the second sur- face 72 faces outwards. The first wedge surface 71 has first and second seg- ments 711, 712 forming an edge 713. Initially (see Fig. 3) the gasket 80 sits on a first ring surface 61 of the peripheral surface 60 with its central portion 83. A portion of the gasket 80 may extend into the first fluid opening 58 and may rest on the optional pusher 90. During installation, the optional pusher 90 may shift the gasket 80 to an intermediate position (not shown) in which the gasket 80 is located on the second ring surface 62. The first shift may be accomplished, e.g. by an optional abutment of the housing cover 20. As soon as the filter is oper- ated, the pressure at the first fluid outlet facing side of the gasket 80 increases and shifts the gasket 80 upwards. Thereby the wedge element 70 facing side of the gasket 80 entrains the wedge element 70 into the position as shown in Fig. 6. When the gasket 80 pushes the wedge element 70 towards the protruding seg- ment 64, the edge 713 slides over the protruding segment 64 of the peripheral surface 60 thereby transforming the axial movement of the gasket 80 into a su- perposition of an axial movement and a radial movement (the first direction 5). Accordingly, the clamping force exerted by the wedge element 70 onto the pe- ripheral surface 60 is thus transferred via the ring shaped edge 713 what pro- vides for an increase of the contact pressure between the wedge element 70 and the protruding segment of the peripheral surface 60.

The example as shown in Fig. 7 and 8 is almost identical to the examples of Fig.3 to Fig. 6 and the description of Fig. 1 to 6 can be read on Fig. 7 and 8 as well. The only difference is again the cross-sectional shape of the wedge ele- ment 70. In this example the wedge element70 has an at least approximately cir- cular shape which as well provides a first wedge surface 71 facing towards the protruding segment 64, a second wedge surface 72 facing outwards and gas- ket 80 facing back side 73.

A further very similar example is depicted in Fig. 9 and 10. Again, the description of Fig. 1 to Fig. 8 can be read on Fig. 9 and Fig. 10 as well. The cross section of the wedge element 70 is preferably at least almost identical the one in Fig. 1 to Fig. 4, but the shape of the protruding segment 64 is different. In this example, the protruding segment 64 forms an edge 643, very similar to the edge 713 in Fig. 5 and 6. Once the fluid pressure is applied, the first wedge surface 71 of the wedge element 70 may slide over the edge 643 of the protruding segment 64, thereby converting the axial movement of the gasket 80 into a superposition of a radial movement and the axial movement as indicated by the arrow 5 symboliz- ing the first direction 5. Thereby the wedge element 70 is clamped into the gap 85(see Fig. 1 and 2) between the protruding segment 64 and housing cover 20, securing the housing cover 20 (see Fig. 1) in place.

Fig. 11 shows a detail of a filter cartridge 1 in a second alternative of locating the protrusion 65 relative to the wedge element 70 and the gasket 80 (referred to above as alternative II). Different to the Examples in Fig. 1 to 10, the protru- sion 65 of the connector 50 is located in between of the first wedge surface 71 or the wedge element 70 and the gasket 80. In Fig. 11 the oil filter cartridge 1 and its components are located in their positions they take in operation. As can be seen, due to the fluid pressure the gasket 80 abuts the gasket facing side of the protrusion 65 and forces the protrusion 65 towards the wedge element 70. Due to this force, the connector 50 is pressed axially against the first wedge sur- face 70, which then slides over the protruding segment 64 in the first direction 5, which in this case is a superposition of the radial direction and the rearward di- rection 4 (in the alternative I it is a superposition of the radial direction and the forward direction 3). Beyond, the description of Fig. 1 to 4 can be read as well on Fig. 11. As apparent, the shape of the wedge element 70 as well as the shape or inclination of the protruding segment 64 of the peripheral surface 60 can be al- tered as shown e.g. in Fig. 5 to Fig. 10.

Fig. 12 and Fig. 13 show a further example of a filter cartridge 1 the filter car- tridge 1 differs from the filter cartridge of Fig. 1 to Fig. 4 only that the second conduit 59 connecting the socket 10 with the fluid channel is not present. In this example the socket 10 directly connects to an opening the filter element 30. The opening may be provided like in this example by an optional front-end cap 33.

But it shall be understood that the socket's fluid inlet could as well directly en- gage into the fluid channel 37. Beyond, the description of Fig. 1 to 4 can be read on Fig. 13 as well. It is noted that the examples being shown in Fig. 5 to Fig. 11 could as well have a connector 50 without the second port 52, without the sec- ond conduit 57 and without the second fluid opening 59. Or to say it the other way, the examples protrusions 65 and the example wedge-elements 70 and their example orientations to another could as well transferred to the connector 50 of the filter cartridge in Fig. 12 and 13.

In all depicted examples a preferred example gasket 80 has been shown. It comes without saying that any gasket 80, being configured to slide on the pe- ripheral surface 60 while sealing the gap 84 can be used. The shape of the gas- ket 80 is not relevant. In the simplest example, the gasket 80 may be an O-ring, alternatively the gasket 80 may have a polygonal (e.g. rectangular) or oval cross section or combinations thereof. Further, there is no necessity that the first ring surface 61 and the second ring surface 62 have different radii. The shown rela- tion of the radii may as well be inverted as explained above.

List of reference numerals

1 filter cartridge

2 longitudinal axis

3 forward direction

4 rearward direction

5 first direction

6 second direction

10 socket

15 housing cover facing rim

20 housing cover

25 sealing surface

30 filter element

33 front-end cap

34 rear-end cap

37 fluid channel

50 connector element / connector

51 first fluid port

52 second fluid port

53 forward-facing side

54 rearward-facing side

55 spacer element

56 first conduit

57 second conduit

58 first fluid opening

59 second fluid opening

60 peripheral surface of connector element

61 first ring surface second ring surface intermediate ring surface protruding segment block/protrusion protruding edge wedge element first wedge surface first segment of first wedge surface second segment of first wedge surface edge in first wedge surface second wedge surface back side of wedge / gasket facing surface of wedge element edge in first wedge surface crest on surface of wedge element / elongate protrusions gasket first leg second leg central portion gap / groove first gasket portion second gasket portion pusher