Filter System with a Filter Element and a Safety Assembly, a Safety Assembly, and a Filter Element

The invention relates to a filter system comprising a housing and a filter element being accommodated in the housing, wherein a safety assembly is arranged inside the housing, having a blocking mode and an unblocking mode depending on an axial and/or rotational position of the filter element in the housing and being configured to provide access of a sealing structure of the filter element to a sealing area of the safety assembly in the unblocking mode and to block access of the sealing structure to the sealing area in the blocking mode when the sealing structure of the filter element is moved towards the sealing area. The invention further relates to a safety assembly for a filter system, and a filter element.

TECHNICAL FIELD

The invention relates to a filter system with a filter element and a safety assembly, a safety assembly and a filter element for such a filter system.

PRIOR ART

Such filter systems or filter elements are used for filtering gaseous or liquid fluids. In internal combustion engine vehicles and industrial engines such filter systems are used for filtering especially fuel, especially diesel fuel or gasoline, engine oil or hydraulic oil.

US 20150033689 A1 discloses a filter system for filtering fluids which has a housing, an inlet, and an outlet. A filter element is arranged inside the housing. A cover closes the housing and provides access to the filter element inside the housing. A securing device prevents the housing from being closed by the cover when the filter element is missing. The filter element has at least one filter element guide path section. The housing or the cover has a rim area with at least one rim guide path section. The filter element guide path section and the rim guide path section supplement one another to a guide path. The securing device comprises at least one securing element arranged on the cover or the housing. The securing element is guided on the guide path when a closing movement is carried out for closing the housing by the cover.

U.S. Pat. No. 9,044,698 B2 displays a fluid filter with a housing, a releasable cover, and a replaceable filter having a filter body and two end discs. The filter is plugged onto a housing pipe and a locking ring is guided on the pipe, preloaded in a push-out direction. The locking ring is locked in a pushed-out position by a locking device. An unlocking device guided by the filter unlocks the locking device when the filter is pushed onto the pipe and enables the locking ring and the filter to be pushed in. When the filter is fitted into the housing, a seal on the end disc or locking ring interacts with a housing sealing surface to separate an untreated filter side from a clean side. When the locking ring is in the pushed-out position and the filter bears against the locking ring, the seal is held away from the sealing surface of the housing.

From DE 10 2016 124587 A1 a positioning device is known, comprising a positioning guide element for positioning a first component relative to a second component to be connected thereto, in the peripheral direction of the second component, wherein, in the process of connecting the two components, the positioning guide element interacts with a positioning guide track on the second component in a positioning manner.

U.S. Pat. No. 9,731,235 B2 shows a filter appliance including a filter housing and a ring filter element having an axis and being mountable in the filter housing. The filter element may include a first axial end disc having a protruding pin configured to engage into a channel of the filter housing. The filter housing may have an interior including a first region and the ring filter element may include a second region associated with the first region.

DISCLOSURE OF THE INVENTION

It is an object of the invention to provide a filter system with a filter element and a safety assembly which allows for a reliable and correct mounting of the filter element.

Another object of the invention is to provide a safety assembly for such a filter system.

Another object of the invention is to provide a filter element for such a filter system.

The first object is achieved by a filter system comprising a housing with a housing head and a housing cover, a fluid inlet and a fluid outlet and a filter element being accommodated in the housing, the filter element comprising a center pipe having a longitudinal direction and being surrounded by a filter bellows, the filter bellows comprising an end cap at one or both of its end regions, the filter element further comprising a sealing structure, particularly a gasket, at the end cap, wherein a safety assembly is arranged inside the housing, having a blocking mode and an unblocking mode depending on an axial and/or rotational position of the filter element in the housing and being configured to provide access of the sealing structure of the filter element to a sealing area of the safety assembly in the unblocking mode and to block access of the sealing structure of the filter element to the sealing area of the safety assembly in the blocking mode when the sealing structure of the filter element is moved towards the sealing area; the safety assembly having a first section arranged at the housing and a second section arranged at the filter element, the first and second sections comprising at least one blocking element and at least one unblocking element configured to cooperate with the at least one blocking element, the at least one blocking element comprising an activation surface and the at least one unblocking element comprising a cam for pushing the activation surface in a radial direction when a contact between the cam and the activation surface is established.

Another object is achieved by a safety assembly for a filter system according to any one of the preceding claims, the filter system comprising a filter element and a housing, having a sealing area and having a blocking mode and an unblocking mode depending on an axial and/or rotational position of the filter element in the housing and being configured to provide access of a sealing structure of the filter element to a sealing area of the safety assembly in the unblocking mode and to block access of the sealing structure of the filter element to the sealing area in the blocking mode when the sealing structure of the filter element is moved towards the sealing area, having a first section arranged at the housing and a second section arranged at the filter element, the first and second sections comprising at least one blocking element and at least one unblocking element configured to cooperate with the at least one blocking element, the at least one blocking element comprising an activation surface and the at least one unblocking element comprising a cam for pushing the activation surface in a radial direction when a contact between the cam and the activation surface is established.

Another object is achieved by a filter element for a filter system according to any one of the claims1to9, comprising a center pipe having a longitudinal direction and being surrounded by a filter bellows, the filter bellows comprising an end cap at one or both of its end regions, and comprising a section of a safety assembly with either at least one unblocking element or at least one blocking element configured to cooperate with either the at least one blocking element or the at least one unblocking element of a first section of the safety assembly, the filter element further comprising a sealing structure, particularly a gasket, on one of its end regions.

Favorable embodiments and advantages of the invention are apparent from the further claims, the description and the drawings.

In a first aspect of the invention a filter system is proposed, comprising a housing with a housing head and a housing cover, a fluid inlet and a fluid outlet and a filter element being accommodated in the housing, the filter element comprising a center pipe having a longitudinal direction and being surrounded by a filter bellows, the filter bellows comprising an end cap at one or both of its end regions, the filter element further comprising a sealing structure, particularly a gasket, at the end cap. A safety assembly is arranged inside the housing, having a blocking mode and an unblocking mode depending on an axial and/or rotational position of the filter element in the housing and being configured to provide access of the sealing structure of the filter element to a sealing area of the safety assembly in the unblocking mode and to block access of the sealing structure of the filter element to the sealing area of the safety assembly in the blocking mode when the sealing structure of the filter element is moved towards the sealing area. The safety assembly has a first section arranged at the housing and a second section arranged at the filter element, the first and second sections comprising at least one blocking element and at least one unblocking element configured to cooperate with the at least one blocking element. The at least one blocking element comprises an activation surface and the at least one unblocking element comprising a cam for pushing the activation surface in a radial direction when a contact between the cam and the activation surface is established.

The inventive filter system comprises a safety assembly for ensuring a correct and reliable mounting of the filter element to the housing of the filter system. The safety assembly comprises two sections where the first section is arranged at the housing and the second section is arranged at the filter element, preferably at a center pipe or a ring structure connected to the center pipe of the filter element. The first section is arranged at the housing cover or at the housing head of the filter system. Both sections are cooperating when mounting the filter element to the housing.

Before mounting of the filter element to the housing the safety assembly is in a blocking mode where access of a sealing structure of the filter element to a sealing area of the safety assembly is blocked by a blocking element. Connection of the sealing structure and the sealing area is needed for a proper sealing of a raw fluid region in the filter system against a filtered fluid region.

The sealing may favorably comprise a sealing surface circumferencing the blocking element for sealing a raw fluid region of the filter system against a filtered fluid region by interacting with the sealing structure of the filter element.

The access may be unblocked when a filter element with a corresponding unblocking element is mounted to the blocking element. The blocking element may be realized by a construction cage with a spring member, whereas the unblocking element may be realized by a cam arranged at the center pipe, the cam cooperating with the spring member in an appropriate manner to unblock the sealing area. For this purpose, the cam may be arranged at the center pipe pointing radially inwards. The cam may be uniformly made with the center pipe.

In a favorable embodiment the blocking element may be arranged at the first section in the housing of the filter system, whereas the unblocking element may be arranged at the second section of the safety assembly in the filter element. Yet, in another embodiment the blocking element may also be arranged at the second section in the filter element and the unblocking element may be arranged at the first section in the housing.

Favorably the safety assembly may also comprise facilities to fix the filter element to the safety assembly and thus to fix the filter element to the housing cover or housing head. This may be achieved by locking the center pipe of the filter element to the blocking element of the safety assembly. Due to another embodiment an end cap of the filter element may be locked by the blocking element thus fixing the filter element to the housing of the filter system.

A further advantage of the inventive filter system is that no positioning of the filter element is needed due to some self-positioning structure and guiding grooves of the blocking element of the safety assembly. These structures lead the filter element during mounting in a longitudinal direction by a guiding rotation into the correct position in the housing. Further the filter element is led to an end position where it is fixed by the safety assembly in a locked position. The guiding grooves can be straight in axial direction or curved. In a further embodiment the guiding groove has at least on straight section in axial direction or around the circumference perpendicular to the center line and at least section around the circumference inclined to the center line.

The fluid inlet as well as the fluid outlet may be favorably arranged in the housing head.

According to a favorable embodiment of the filter system the blocking element may comprise a spring member comprising the activation surface and a radially protruding lip, wherein the lip is retractable from its blocking position by pushing the activation surface in a radial direction. The spring member may favorably realize the blocked mode where the lip is in protruded position and blocks an access to the sealing area of the safety assembly. By pushing the activation surface in a radially inward direction the lip may be pushed back too, thus switching to the unblocked mode where access of the sealing structure of the filter element to the sealing area may be granted.

The blocking element may favorably be connected to the housing head or housing cover of the filter system.

According to a favorable embodiment of the filter system the blocking element may comprise a positioning structure connected to a guiding groove which leads the unblocking element to the activation surface by a rotational movement when moving the filter element in the longitudinal direction towards the blocking element. A further advantage of the inventive filter system is that no positioning of the filter element is needed due to some self-positioning structure and guiding grooves of the blocking element of the safety assembly. These structures lead the filter element during mounting in a longitudinal direction by a guiding rotation into the correct position in the housing.

According to a favorable embodiment of the filter system the blocking element may comprise a locking structure wherein the filter element is locked to the blocking element when the cam is inserted into the locking structure by a rotational movement of the filter element after surpassing the activation surface by the cam in the longitudinal direction. Favorably the safety assembly may also comprise facilities to fix the filter element to the safety assembly and thus to fix the filter element to the housing cover or housing head. This may be achieved by locking the center pipe of the filter element to the blocking element of the safety assembly. Thus, the filter element is led to an end position where it is fixed by the safety assembly in a locked position.

According to a favorable embodiment of the filter system the locking structure may be configured as two neighbored ribs on a circumference of the blocking element. The cam may be locked between the two ribs in an axial direction of the filter element. Thus, a movement of the filter element along the longitudinal direction may favorably be inhibited.

According to a favorable embodiment of the filter system the filter element may be locked to the blocking element by the lip of the blocking element when the cam is moved to an end position by a rotational movement of the filter element after surpassing the activation surface by the cam in the longitudinal direction. Due to this further embodiment an end cap of the filter element may be locked by the blocking element thus fixing the filter element to the housing of the filter system. Thus, a movement of the filter element along the longitudinal direction may also be inhibited.

According to a favorable embodiment of the filter system the lip may be overlapping a collar structure of the end cap when the cam is in its end position. By this way an axial movement of the filter element is inhibited because the end cap is locked by the protruded lip of the spring member in one axial direction whereas in the reverse direction the end cap may be blocked by an end plate of the blocking element itself.

According to a favorable embodiment of the filter system the unblocking element may comprise at least one cam at a ring element, which is arranged inside the center pipe, particularly inside a water separator, wherein the cam is pointing radially inwards. In this embodiment an auxiliary structure, the ring element, comprises the cam for interaction with the activation surface of the blocking element. This feature may provide additional freedom to foresee the unblocking element as an additional element which does not need to be fixed to the center pipe but may be mounted in a separate step.

According to a favorable embodiment of the filter system the ring element may be arranged inside the center pipe in a free rotatable manner, particularly in the water separator. The ring element may be inserted before welding of the end cap to the filter bellows. Mounting of the filter element is provided with additional freedom in a rotational position. The embodiment enables for a reliable and correct mounting of the filter element concerning access to the sealing area of the safety assembly.

According to another aspect of the invention a safety assembly for a filter system is proposed, the filter system comprising a filter element and a housing, having a sealing area and having a blocking mode and an unblocking mode depending on an axial and/or rotational position of the filter element in the housing and being configured to provide access of a sealing structure of the filter element to a sealing area of the safety assembly in the unblocking mode and to block access of the sealing structure of the filter element to the sealing area in the blocking mode when the sealing structure of the filter element is moved towards the sealing area. The safety assembly has a first section arranged at the housing and a second section arranged at the filter element, the first and second sections comprising at least one blocking element and at least one unblocking element configured to cooperate with the at least one blocking element. The at least one blocking element comprises an activation surface and the at least one unblocking element comprises a cam for pushing the activation surface in a radial direction when a contact between the cam and the activation surface is established.

The safety assembly may favorably ensure a correct and reliable mounting of the filter element to the housing of the filter system. The safety assembly comprises two sections where the first section is arranged at the housing and the second section is arranged at the filter element, preferably at a center pipe or a ring structure connected to the center pipe of the filter element. The first section is arranged at the housing cover or at the housing head of the filter system. Both sections are cooperating when mounting the filter element to the housing.

Before mounting of the filter element to the housing the safety assembly is in a blocking mode where access of a sealing structure of the filter element to a sealing area of the safety assembly is blocked by a blocking element. Connection of the sealing structure and the sealing area is needed for a proper sealing of a raw fluid region in the filter system against a filtered fluid region.

The access may be unblocked when a filter element with a corresponding unblocking element is mounted to the blocking element. The blocking element may be realized by a construction cage with a spring member, whereas the unblocking element may be realized by a cam arranged at the center pipe, the cam cooperating with the spring member in an appropriate manner to unblock the sealing area.

According to another aspect of the invention a filter element for a filter system is proposed, comprising a center pipe having a longitudinal direction and being surrounded by a filter bellows, the filter bellows comprising an end cap at one or both of its end regions, and comprising a section of a safety assembly with either at least one unblocking element or at least one blocking element configured to cooperate with either the at least one blocking element or the at least one unblocking element of a first section of the safety assembly. The filter element further comprises a sealing structure, particularly a gasket, on one of its end regions.

Before mounting of the filter element to the housing of the filter system the safety assembly may be in a blocking mode where access of a sealing structure of the filter element to a sealing area of the safety assembly is blocked by a blocking element. Connection of the sealing structure and the sealing area is needed for a proper sealing of a raw fluid region in the filter system against a filtered fluid region.

The access may be unblocked when the filter element with a corresponding unblocking element is mounted to the blocking element. The blocking element may be realized by a construction cage with a spring member, whereas the unblocking element may be realized by a cam arranged at the center pipe, the cam cooperating with the spring member in an appropriate manner to unblock the sealing area.

Favorably the filter element may also be fixed to the safety assembly and thus to the housing cover or housing head of the filter system. This may be achieved by locking the center pipe of the filter element to the blocking element of the safety assembly. Due to another embodiment an end cap of the filter element may be locked by the blocking element thus fixing the filter element to the housing of the filter system.

According to a favorable embodiment of the filter element the at least one blocking element may comprise an activation surface and the at least one unblocking element comprises a cam for pushing the activation surface in a radial direction when a contact between the cam and the activation surface is established.

The blocking element in the form of a spring member may favorably realize the blocked mode where a lip is in protruded position and blocks an access to the sealing area of the safety assembly. By pushing the activation surface in a radially inward direction the lip may be pushed back too, thus switching to the unblocked mode where access of the sealing structure of the filter element to the sealing area may be granted.

According to a favorable embodiment multiple spring members may block the safety assembly. At least two spring members, in particular opposed radially, could be integrated in one piece for easier attachment to a single spring strap.

According to a favorable embodiment of the filter element the unblocking element may comprise at least one cam arranged at the center pipe pointing radially inwards. Thus, by moving the filter element in the longitudinal direction the cam at the center pipe gets into contact with the activation surface of the blocking member which is positioned inside the center pipe. The cam pushes the activation surface radially inwards and unblocks the access to the sealing area of the blocking element of the safety assembly.

According to a favorable embodiment of the filter element the unblocking element may comprise at least one cam at a ring element, which is arranged inside the center pipe, wherein the cam is pointing radially inwards, in particular, wherein the ring element is arranged in a free rotatable manner inside the center pipe. In this embodiment an auxiliary structure, the ring element, comprises the cam for interaction with the activation surface of the blocking element. This feature may provide additional freedom to foresee the unblocking element as an additional element which does not need to be fixed to the center pipe but may be mounted in a separate step. The ring element may be inserted before welding of the end cap to the filter bellows. Mounting of the filter element is provided with additional freedom in a rotational position. The embodiment enables for a reliable and correct mounting of the filter element concerning access to the sealing area of the safety assembly.

In another embodiment of the safety assembly a sloped guiding groove could be used to get a smoother guiding.

In another embodiment an additional positioning device at the safety element could prevent incorrect assembly. Preferably at least two additional extensions can be arranged on the circumference of the center tube or ring element. Only when all extensions fit into the corresponding groove on the counterpart, the filter element can be mounted into the filter housing or the filter cover. These positioning devices could be combined with any of the preceding embodiments and the number of extensions and corresponding cutouts could be adapted to the functional requirement.

Between the extensions and the opening of the guiding groove an any angle can be set up to secure the assembly of the right filter element. The quantity of extensions and the value for the angle can be adapted to technical functions. The extensions can be positioned rotationally symmetrical or in another pattern.

According to a favorable embodiment of the filter element the blocking element may comprise a spring member with the activation surface and a radially protruding lip, wherein the lip is retractable from its blocking position by pushing the activation surface in a radial direction. The spring member may favorably realize the blocked mode where the lip is in protruded position and blocks an access to the sealing area of the safety assembly. By pushing the activation surface in a radially inward direction the lip may be pushed back too, thus switching to the unblocked mode where access of the sealing structure of the filter element to the sealing area may be granted.

DETAILED DESCRIPTION OF THE DRAWINGS

In the drawings, like elements are referred to with equal reference numerals. The drawings are merely schematic representations, not intended to portray specific parameters of the invention. Moreover, the drawings are intended to depict only typical embodiments of the invention and therefore should not be considered as limiting the scope of the invention.

FIG.1depicts a cut view through a filter system100with a safety assembly130and a filter element10according to an embodiment of the invention.

The filter system100comprises a housing110with a housing head112and a housing cover114, a fluid inlet102and a fluid outlet104and a filter element10being accommodated in the housing110. The filter system100may be used for filtering fluids, particularly for engine oil or hydraulic oil. The filter element10is mounted to the housing cover114and then the housing cover114with the filter element10is mounted to the housing head112by inserting it into the housing head112. The housing110is closed by tightening the screw connection116, in particular a screw connection116with a thread of the housing head112fitting into a thread of the cover114.

The filter element10separates a raw fluid region40inside the housing110from a filtered fluid region42by being sealed on the first end cap with the gasket34against the sealing surface146of the sealing area144of the blocking element140and on the other end cap21with the gasket36against the fluid outlet104in the housing head112.

Fluid to be filtered enters the housing110of the filter system100through the fluid inlet102, passes the filter bellows12from the raw fluid region40on the outside of the filter element10to the filtered fluid region42on the inside of the filter element10. The filtered fluid exits the housing110through the fluid outlet104. Fluid inlet102and fluid outlet104are both arranged in the housing head112.

For changing the filter element10due to maintenance action the housing cover114is unscrewed and dismounted from the housing head112together with the filter element10.

The filter element10comprises a center pipe14having a longitudinal direction L and being surrounded by a filter bellows12. The filter bellows12comprises end caps20,21at both of its end regions16,18. The filter element10further comprises a sealing structure32with a gasket34at the end cap20for sealing against a safety assembly130, whereas a second gasket36is provided at the other end cap21for sealing against the fluid outlet104of the housing head112.

The safety assembly130is arranged inside the housing110and exhibits a blocking mode and an unblocking mode depending on an axial and/or rotational position of the filter element10in the housing110. The safety assembly130is configured to provide access of the sealing structure32of the filter element10to a sealing area144of the safety assembly130in the unblocking mode and to block access of the sealing structure32of the filter element10to the sealing area144of the safety assembly130in the blocking mode when the sealing structure32of the filter element100is moved towards the sealing area144.

The safety assembly130has a first section132arranged at the housing110and a second section134arranged at the filter element10. The first section132comprises a blocking element140. The second section134comprises an unblocking element180configured to cooperate with the blocking element140. The blocking element140comprises an activation surface148. The unblocking element180comprises a cam188for pushing the activation surface148in a radial direction when a contact between the cam188and the activation surface148is established.

The blocking element140comprises a spring member150comprising the activation surface148and a radially protruding lip152, wherein the lip152is retractable from its blocking position by pushing the activation surface148in a radial direction. The blocking element140is fixed to the housing cover114by mounting members172which are extended in the longitudinal direction L and arranged in a circumference at a radial distance from the axis L.

FIG.2depicts a cut view through the filter element10of the filter system100connected to the blocking element140as the first section132of the safety assembly130.

The safety assembly130has the sealing area144and has a blocking mode and an unblocking mode depending on an axial and/or rotational position of the filter element10in the housing110. The safety assembly130is configured to provide access of the sealing structure32of the filter element10to the sealing area144of the safety assembly130in the unblocking mode and to block access of the sealing structure32of the filter element10to the sealing area144in the blocking mode when the sealing structure32of the filter element100is moved towards the sealing area144.

The safety assembly130has the first section132arranged at the housing cover114of the filter system and the second section134arranged at the filter element10. The first section132comprises the blocking element140and the second section134comprises at least one unblocking element180configured to cooperate with the blocking element140.

The blocking element140comprises the activation surface148, whereas the unblocking element180comprises a cam188for pushing the activation surface148in a radial direction when a contact between the cam188and the activation surface148is established.

InFIG.3a perspective view of the first section132of the safety assembly130is depicted, whereas inFIG.4a cut perspective view of the first section132of the safety assembly130is shown.

The blocking element140as part of the first section132comprises two spring members150comprising the activation surface148and a radially protruding lip152. The lip152is retractable from its blocking position by pushing the activation surface148in a radial direction. The spring members150are arranged opposite to each other in the blocking element140.

The blocking element140comprises a positioning structure160connected to a guiding groove162which leads the unblocking element180to the activation surface148by a rotational movement when moving the filter element10in the longitudinal direction L towards the blocking element140. The interaction of the safety assembly130is shown in detail inFIGS.6to12.

The blocking element140further comprises a locking structure164wherein the filter element10is locked to the blocking element140when the cam188is inserted into the locking structure164by a rotational movement of the filter element10after surpassing the activation surface148by the cam188in the longitudinal direction L. The locking structure164is configured as two neighbored ribs166,168on a circumference of the blocking element140.

The filter element10is locked to the blocking element140by the protruded lip152a the spring member150of the blocking element140when the cam188is moved to an end position170by a rotational movement of the filter element10after surpassing the activation surface148by the cam188in the longitudinal direction L.

The safety assembly130has interlocking means135that prevent a movement, in particular a rotation of the safety assembly130when installed. For example, radially outward extending ribs can engage in corresponding recesses on the counterpart. In another embodiment, the interlocking means135can be recesses at safety assembly130into which the projections protrude from the counterpart.

FIG.5depicts a cut perspective view of the filter element10.

The filter element10comprises the center pipe14with the longitudinal direction L which is surrounded by the filter bellows12. The filter bellows12comprises end caps20,21at its end regions16,18. The filter element10further comprises the second section134of the safety assembly130with two unblocking elements180which are opposite to each other arranged and configured to cooperate with the blocking elements140of the first section132of the safety assembly130.

The filter element10further comprises a sealing structure32with a gasket34on its end region16.

InFIGS.6to12successive steps of the interaction of the sections132,134of the safety element130during mounting of the filter element10are depicted in perspective and cut views. The filter element10is only shown with its end cap20and the two opposing cams188in order to get a free view on the interaction behavior of the different elements.

The process starts inFIG.6where the cam188is led via the positioning structure160to the guiding grooves162of the blocking element140. The spring members150is in its starting position where the lip152is protruded and blocks the access of the sealing structure32at the end cap20to the sealing area144of the blocking element140.

The movement of the cam188is indicated by black arrows.

By moving the filter element10in the longitudinal direction L to the blocking element140the cam188is guided in the guiding groove162to the activation surface148of the spring member150, as shown inFIG.7.

InFIG.8the cam188pushes the activation surface148radially inwards such that the lip152is radially withdrawn. Thus, the safety assembly130is in the unblocking mode. In this mode the sealing structure32of the end cap20with the gasket34may glide to the sealing surface146of the sealing area144of the blocking element140.

InFIG.9the cam188has surpassed the activation surface148. The end cap20is in its final position where the gasket34of the sealing structure32is pressed tightly at the sealing surface146of the sealing area144.

Now the filter element10may be rotated, as indicated inFIG.10, thus moving the cam188to the end position170between the neighboring rips166,168. In this position, shown inFIGS.11and12, the filter element10is locked in this locking structure164with the cams188between the rips166,168.

FIG.13depicts a perspective view of a first section132of a safety assembly130according to a second embodiment of the invention. InFIG.14a cut perspective view of the first section132is shown.

In this embodiment the activation surface148of the spring member150exhibits a different shape so that the activation surface148is still in contact with the cam188when the cam188is at its end position at the rib166. The effect of this behavior on the interaction of the safety assembly130is shown inFIGS.16to22.

FIG.15depicts a cut perspective view of a filter element10according to the second embodiment of the invention.

The principal structure is the same as with the first embodiment shown inFIG.5. The main difference is that the end cap20comprises a collar structure26extending in the longitudinal direction L connected to the sealing structure32.

InFIGS.16to22successive steps of the interaction of the sections132,134of the safety element130during mounting of the filter element10according to the second embodiment of the invention are depicted in perspective and cut views.

InFIGS.16and17the guiding process of the cam188in the guiding groove162towards the interaction surface148of the spring element150is shown, which resembles the process for the first embodiment, shown inFIGS.6and7. A major difference of the blocking element140is that it only exhibits one rib166and is missing the second rib168of the first embodiment.

InFIG.18the cam188pushes the activation surface148radially inwards such that the lip152is radially withdrawn. Thus, the safety assembly130is in the unblocking mode. In this mode the sealing structure32of the end cap20with the gasket34may glide to the sealing surface146of the sealing area144of the blocking element140.

InFIG.19the cam188has partly surpassed the activation surface148, but part of the cam188is still pushing the activation surface148inwards because it has a longer extension along the longitudinal direction L that in the first embodiment. Thus, the lip152is still recessed radially inwards, despite the cam188has reached the rib166of the blocking element140.

InFIG.20it is depicted, indicated by the black arrow, that now the filter element10is rotated to the end position170. The cam188is shown inFIG.21on part of the way to the end position. Now the activation surface148no longer is pushed inwards so the lip152is protruded again.

This process leads to the situation, depicted inFIG.22, where the lip152is overlapping the collar structure26of the end cap20when the cam188is in its end position170. Thus, the filter element10is locked in its axial movement along the longitudinal direction L. The end cap20is in its final position where the gasket34of the sealing structure32is pressed tightly at the sealing surface146of the sealing area144.

FIG.23depicts a cut view through a filter system100with a safety assembly130and a filter element10according to a third embodiment of the invention. The filter system100may be used for filtering fluids, particularly for fuel of internal combustion engines.

The filter system100comprises a housing110with a housing head112and a housing cover114which are fit together by a screw connection116. A fluid inlet102is arranged in the housing head112as well as a fluid outlet114, which is not visible in the Figure. Also, a hand pump118is arranged in the filter head112for conveying fuel after maintenance action.

The first section132of a safety assembly130with a blocking element140in this embodiment is connected to the housing head112. So the filter element10is mounted to the housing head112before closing the housing110by screwing the housing cover114to the housing head112by tightening the screw connection116of the housing110. The filter element10is sealed to the housing cover114by a gasket36on a radial circumference of the end cap20on the lower end region16.

On the other end region18the filter element10comprises a sealing structure32with a gasket34at the end cap21to be sealed against a sealing surface146of a sealing area144of a blocking element140like for the other embodiments.

The unblocking element180of the second section of the safety assembly130in the filter element10comprises at least one cam188at a ring element28, which is arranged inside the center pipe14, and in the embodiment shown particularly inside a water separator30. The cam188is pointing radially inwards. The ring element28is arranged inside the water separator30in a free rotatable manner.

FIG.24depicts a cut view through the filter element10of the filter system100ofFIG.23connected to the blocking element140.

The unblocking element180comprises two opposite arranged cams188at the ring element28, which is arranged inside the center pipe14. The cam188is pointing radially inwards. The ring element28is arranged in a free rotatable manner inside the center pipe14.

The ring element28may be mounted to the filter element10after inserting the water separator30into the center pipe14and before closing the filter element10with the end cap21. After mounting the end cap21to the filter bellows12the ring element28may be fixed in the longitudinal direction L of the filter element10but remain freely rotatable.

As can be seen in the Figure the filter element10is sealed against the blocking element140but is not fixed in the longitudinal direction L. The filter element10may still be removed by moving the filter element10from the blocking element140in the longitudinal direction L.

The blocking element140comprises an activation surface148and the at least one unblocking element180comprises a cam188for pushing the activation surface148in a radial direction when a contact between the cam188and the activation surface148is established.

The unblocking element180comprises at least one cam188arranged at the center pipe14pointing radially inwards.

InFIG.25a perspective view of the first section132of the safety assembly130according to the third embodiment of the invention is shown, whereas inFIG.26a cut perspective view of the first section132is depicted.

The blocking element140comprises two spring members150with the activation surface148and a radially protruding lip152, wherein the lip152is retractable from its blocking position by pushing the activation surface148in a radial direction. So the structure of the blocking element140is very similar to the other embodiments. A main difference is that the guiding groove162is not exhibiting a bending shape but is directed straight in the longitudinal direction L. Thus, by mounting the filter element10to the blocking element140there is no rotational movement involved. In the depicted embodiment both spring members150are integrated in one piece for easier attachment to a single spring strap.

FIG.27depicts a cut perspective view of the filter element10according to the third embodiment of the invention. Mounting of the water separator30as well as the ring element28with the two opposed arranged cams188inside the water separator30may be seen in more details.FIG.28depicts a perspective view of the ring element28separately.

In theFIGS.29to33successive steps of the interaction of the sections132,134of the safety element130during mounting of the filter element10according to the third embodiment of the invention is depicted in perspective and cut views.

FIGS.29and30depict the insertion process of the filter element10by moving the cam188of the unblocking element180along the guiding groove162, indicated by the black arrows.

In the cut view inFIG.31the cam188is just before activating the activating surface148of the spring member150. Thus, the access of the sealing structure32to the sealing area144of the blocking element140is still in the blocked mode.

InFIG.32the activation surface148is pushed radially inwards by the cam188, recessing the lip152, such that the safety assembly130is in the unblocked mode and access of the sealing structure32of the filter element10to the sealing area144of the blocking element140is open.

Thus, the gasket34of the sealing structure32may glide over the sealing surface146of the sealing area144until there is a tight sealing between the end cap21and the blocking element140.

The cam188has surpassed the activation area148such that the lip152is protruded again. For demounting the filter element10it has just to be pulled in the other direction to open access again by activating the activation surface148by the cam188.

FIGS.34and35show in another perspective as a supplementary illustration the assembly of the safety assembly130with the mounting members in an additional embodiment with a sloped guiding groove162, inFIG.35partially depicting the center tube14of the filter element10.

In a further embodiment according toFIGS.36and37the safety element130has a further positioning device. Two additional extensions190are arranged on the circumference of the center tube14or ring element28. Only when all extensions188,190fit into the corresponding groove162,191on the counterpart, the filter element can be mounted into the filter housing110or the filter cover114. These positioning devices190,191can be combined with any of the preceding embodiments. The number of extensions190and corresponding cutouts191can be adapted to the functional requirement.

The safety assembly130is displayed inFIG.38in a view from position structure160into the safety assembly130. In this view the positioning extensions190with the corresponding cutouts191are visible. Between the extensions190and the opening of the guiding groove162angle X° is set up. With this option only the suitable filter element10can be assembled.

FIG.39shows a top view of the center pipe14with unblocking elements180, cams188and the extensions190as position device. Between cams188and extensions190angle X° is set up. The quantity of extensions and the angle X° can be adapted to technical functions.

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