FILTER DEVICE

Abstract

A filter device, having a filter housing (2) in which an exchangeable filter element (14) is accommodated, is characterized in that the filter element (14) has a securing device (58) that can be inserted axially into a receiving device (20) of the filter housing (2), in that, after a rotational motion has been performed, snap means (70) are used to snap the securing device (58) to the receiving device (20) in a snap position.

Description

The invention relates to a filter device, having a filter housing in which a replaceable filter element is accommodated. More specifically, the invention relates to a return filter device provided for in-tank installation.

Filter devices of this type are state of the art, cf. DE 10 2015 007 691 A1. The space-saving installation in a hydraulic tank renders such filter devices suitable for use in compact hydraulically driven devices where there is little available installation space. The in-tank installation also permits a simple structure of the filter housing, formed by a cover that can be removably attached to the flange of a tank opening and a relatively thin-walled pipe extending at a distance from the filter element from the cover into the interior of the tank to a position lower than the operational fluid level.

Based on this prior art, the invention addresses the problem of providing a filter device of the type regarded above, which is characterized by an improved and safe operating performance while maintaining the advantages achieved in the prior art.

According to the invention said problem is solved by a filter device having the features of claim 1 in its entirety.

According to the characterizing part of claim 1, an essential feature of the invention is the filter element having a securing device that can be inserted axially into a receiving device of the filter housing, wherein, after a rotational motion has been performed, snap means are used to snap the securing device to the receiving device in a snap position. Preferably, provision is made that in the snap position, while forming a lock, in particular against axial disassembly, contact surfaces of the securing device and of the receiving device, which are assigned to each other in pairs, are in contact with each other when the device is not in operation. In this way, at least when the device is not in operation, the filter element is secured axially downwards in its functional position in the filter housing under the effect of its weight, wherein the radially acting frictional force between the said contact surfaces also counteracts any radial disassembly. This mutual contact, achieved by a rotational motion into the snap position, provides a form-fitting engagement to secure the securing device and the receiving device against axial forces acting at least downwards in the lift-off direction. The snap means effective in the snap position, secure the securing device and the receiving device to each other in the rotational position of form-fitting engagement of the contact surfaces.

In a preferred embodiment of the filter device according to the invention, provision is made that at least one further pair of contact surfaces in the form of a guide surface on the securing device and a further guide surface on the receiving device now secures the filter element against its weight force by contact of the guide surfaces to each other during operation of the filter device under the fluid pressure produced. Because of this surface limitation, the motion of the filter element during operation of the device is also counteracted axially upwards, wherein again the friction between said surfaces has the effect that the filter element is likewise secured against unintentional radial disassembly. In this respect, the contact between the above-mentioned contact surfaces is then relieved of the securing device and of the receiving device.

In advantageous exemplary embodiments, the securing device can be inserted into the receiving device of the filter housing against the force of an energy storage acting on the filter element. In addition to the snap means, the force closure at the contact surfaces generated by the action of the energy storage forms an additional safeguard against rotation from the snap position, so that a particularly secure positional fixing of the filter element is ensured in any operating state of the device.

Advantageously, the arrangement may be such that the securing device is part of an end cap of the filter element, wherein said securing device has securing bars projecting axially from the end cap, wherein said securing bars have the assignable snap means and a part of the contact surfaces. Advantageously, the receiving device can be part of a cover forming a housing part of the tank filter, wherein said cover can be attached to the tank flange of a tank opening.

The snap means can be formed by snap hooks projecting radially beyond the axial orientation of the securing bars and springing back and engaging with assignable snap recesses in the receiving device in the snap position, requiring low actuation forces.

In advantageous exemplary embodiments, the receiving device has guideways, which, following a predeterminable course of curvature, guide the filter element inserted axially into the filter housing during its rotational motion until it reaches the snap position, preventing operational errors.

Advantageously, the arrangement can be made in such a way that the guideways each have an interruption for the passage of an assignable snap-in hook each when the filter element is inserted axially, which contributes to a fail-safe assembly.

At least some of the interruptions can have a control surface, which lifts the respective snap hook during the rotational motion out of the interruption for its further travel into the snap position, which also facilitates the self-explanatory assembly.

In this case, the arrangement can advantageously be made in such a way that, during continued rotational motion after the respective snap hook has been lifted out of the assigned interruption, the snap hook passes over a further guide part which, projecting radially outwards from a curved path, also supports the snap hooks in their snap position. In this way, a particularly secure snap-fit connection is achieved.

The further guide part can as a hollow box be integrally formed on the respective guideway, wherein the guide part engages with a further, additional guide surface in an axial clearance between the snap hook and the contact surface of the securing bar, which helps to support the guiding process until the snap-fit connection is achieved and ensures that the element does not unintentionally fall out of the holder in the axial direction.

In advantageous exemplary embodiments, when the rotational motion into the snap position of the filter element in the assigned filter housing is completed, the respective snap hook engages with a recess in the guideway, which adjoins the respective further guide part in the direction of rotation associated with this rotational motion.

In particularly advantageous exemplary embodiments, the energy storage, formed as a compression spring, is a component of a bypass valve, the closing part of which preloads the filter element in the opposite direction to its axial insertion motion.

The invention is explained in detail below with reference to an exemplary embodiment shown in the drawing.

In the Figures:

FIG. 1 shows a perspective oblique view of an exemplary embodiment of the filter device according to the invention;

FIG. 2 shows, sectioned in a vertical plane, a perspective oblique view of the exemplary embodiment;

FIG. 3 shows a perspective oblique view of the separately depicted filter element of the exemplary embodiment;

FIG. 4 shows an oblique perspective view of the exemplary embodiment sectioned in the area of the cover in a horizontal sectional plane, wherein interacting parts of the cover and filter element are shown in the position at a first stage of the insertion process;

FIGS. 5 and 6 are corresponding to FIG. 4, wherein the positions at a second and a third stage of the insertion process, respectively, are shown; and

FIG. 7 shows a perspective oblique view of the part of the exemplary embodiment adjoining the cover, drawn on a larger scale and sectioned with a vertical sectional plane.

With reference to the accompanying drawings, the invention is explained using the example of a return filter intended for installation in a tank (not shown). The exemplary embodiment has a filter housing designated as a whole by the reference numeral 2, which is formed by a cover 4 and an outlet pipe 6. The cover 4 has a male thread 8, which can be used to screw it to a tank flange 10, which is located at a tank opening of the tank not shown. The upper end of the discharge pipe 6, in the form of a thin-walled hollow cylinder, rests against the inside of the cover 4. In this case, a fastener can be provided at the cover 4, or the pipe 6 can be secured to the cover 4 by a support from the lower end 12. The outlet pipe 6, which encompasses a filter element 14 inserted in the housing 2 at a radial distance, has windows 16 for the outflow of filtrate, wherein said windows 16 are arranged on the pipe 6 at such a height that the filtrate flows out into the tank at a height that favors degassing even for a small tank volume. As indicated in FIG. 2 by several overlap points 18, the outlet pipe 6 can be composed of several pipe segments, which can be used to implement filter housings 2 of desired lengths.

The interior 20 of the cover 4, wherein said interior 20 has the shape of a circular, flat bowl, forms the receiving device for the filter element 14, which is shown separately in FIG. 3. Between an upper end cap 22 and a lower end cap 24, the filter element 14 has a hollow-cylindrical filter medium 26 that encompasses an inner filter cavity 28 on the inside and is supported by a support tube 30 on its outside. The support tube, formed from a plastic grid structure, is composed of tube segments 30, similar to the outlet pipe 6, wherein said tube segments 30 are interconnected at joints 32. As is most clearly shown in FIGS. 2 and 3, the lower end cap 24 has three circumferentially distributed foot parts 34 that project axially downward and obliquely outward. The circumferential rim of the foot parts 34 form a stop surface 36 for supporting the lower end 12 of the outlet pipe 6. The lower end cap 24 forms the inlet cap for the filter operation and has a central opening 38 through which a return connector 40 passes, through which unfiltered matter passes to the inner filter cavity 28. A movable cap 42 extends above and beyond the inner end of the connecter 40, wherein said cap 42 forms a check valve that prevents back contamination into the tank during maintenance operations. Wall segments 44 extending upwards from the circumferential area of the lower end cap 24, form guides for the lower support tube segment 30.

The top of the upper end cap 22 is formed by a flat circular disc 46, which is closed except for a central opening 48, the rim 50 of which forms the sealing seat for the closing body 52 of a bypass valve. In correspondence to the rim segments 44 on the lower end cap 24, rim segments 56 (FIG. 3) forming the guide for the upper support tube segment 30, extend downward from the circumferential rim 54 of the end cap 22, wherein said circumferential rim 54 forms the enclosure for the filter medium 26 and the upper support tube segment 30. The upper end cap 22 comprises a securing device that interacts for positionally retaining the filter element 14 in the installed functional position with a receiving device located in the interior 20 of the cover 4. The securing device is formed by three securing bars 58 which, see FIG. 3, are offset from one another by 120° and extend near the circumferential rim 54 upwards away from the circular disc 46. For interaction with the securing bars 58, the receiving device has guide tracks and guide parts, which are integrally formed in the interior 20 of the cover 4 on the top wall 60 thereof, which extend therefrom in the direction of the filter element 14 and which form guide tracks and guide parts. The process of installing a filter element 14 is performed in stages, wherein the first stage is inserting the end cap 22 into the interior 20 in an axial motion. Insertion takes place with the filter element 14 in a rotational position, in which the securing bars 58 are each aligned with an insertion space 63, which are free spaces in the interior 20 offset from one another by 120°. The filter element 14 is then rotated in two further stages until it reaches a snap position. During this rotary motion, the securing bars 58 are guided by arc parts 78 (FIGS. 4 to 6) and guide parts. The axial insertion motion occurs against the spring force of a compression spring 62, which is clamped between the top wall 60 and the closing body 52 of the bypass valve and presses the closing body 52 into the closed position at the rim 50 of the opening 48 of the end cap 22, wherein said rim 50 forms the sealing seat.

As shown in FIG. 3, the securing bars 58 have, adjacent to the circular disc 46 of the end cap 22, a foot 64 in the form of a cylindrical shell part, the upper surface of which is delimited by a guide surface 66 extending in a radial plane. From one end of the guide surface 66, and offset radially outwards with respect thereto, a wall part 68 extends upwards from the guide surface 66 in the axial direction and merges with a snap hook 70, which extends along the guide surface 66 and beyond the end of it, while forming an axial clearance. The wall part 68 forms a contact surface 72 with the underside located below the guide surface 66, wherein said contact surface 72, in the snap position shown in FIG. 7, in conjunction with a contact surface 74 of the receiving device, forms a pair of blocking surfaces interacting in a form-fitting manner with each other, wherein said pair of blocking surfaces prevents the filter element 14 from moving axially downwards as viewed in the direction of FIG. 7.

Provision is further made that at least one further pair of contact surfaces in the form of the guide surface 66 on the securing device 58 and a further guide surface 76 on the mount 20 is provided. These now provide, in particular during operation of the device under the resulting fluid pressure, for the filter element 14 to be secured against its weight force by the contact of said guide surfaces 66, 76 with each other. By this limitation of the surface, the motion of the filter element 14 during operation of the device is also countered axially upwards when viewed in the direction of FIG. 7. A corresponding friction between said pairs of surfaces 72, 74; 66, 76 causes the filter element 14 to be equally secured within the filter housing 2 against any unintentional radial disassembly.

FIG. 4 shows the situation during the first stage of the installation process of the filter element 14. In this insertion-rotation position, the snap hooks 70 are located in the region of an interruption 77 each of a main guideway formed by the arc parts 78, wherein said main guideway forms the guide for the snap hooks 70 during the rotational motion. The interruptions 77 provide in the interior 20 of the cover 4 the insertion space 63 as a free space for the axial insertion motion of the securing bars 58 with the snap hooks 70, such that a rotational position is predetermined for the insertion motion as the first stage of the installation process. At each of the interruptions 77, a control surface 80 each forms the transition to the next arc part 78, wherein the control surface 80 has the shape of a ramp sloping radially outwards.

During the second stage of the installation process, in which the filter element 14 is rotated (clockwise when viewed in the direction of FIGS. 4 to 6), a front control bevel 81 of the snap hooks 70 contacts the respective control surface 80 and thus the snap hooks 70 are lifted radially outwards out of the interruption 77. FIG. 5 shows the rotational position in which the snap hooks 70 interact with the respective control surface 80 for this purpose. Upon further rotational motion, as the third stage of the installation process, the snap hooks 70 are guided on the outside of the adjoining arc part 78 until they reach the snap position shown in FIG. 6, in which a latch 83, formed behind the control slope 81, of the rebounding snap hooks 70 engages in a snap recess 82, thus securing the rotational position in the snap position. During motion between the positions shown in FIGS. 5 and 6, in which the snap hooks 70 are guided on the outside of the arc part 78 until they reach the snap recesses 82, the snap hooks 70 pass over a further guide part formed by one block 84 each integrally formed on the top wall 60, which forms a kind of hollow box having an inner recess, in which the outer contact surface 74 and an upper guide body 90 are located as axial boundaries of the cavity, see FIG. 7.

When the snap position is reached, FIG. 6, the snap hook 70 has overrun the block 84. At the same time, the contact surface 72 and a guide surface 86, extending at a distance along the snap hook 70, of the parts 68 projecting radially outwards from the foot 64 of the securing bars 58 have moved into the cavity in the block 84, such that in the snap position the form-fitting engagement shown in FIG. 7 is formed, in which the abutting contact surfaces 72 and 74 form the safeguard against axial downward forces, the surfaces 66 and 76 form the safeguard against axial upward forces and thus form the barrier against axial disassembly in both directions. Because of the acting spring force of the compression spring 62 of the bypass valve, the contact surfaces 72, 74 are also in force-fit contact with each other in the snap position, so that in addition to the snap engagement of the snap hooks 70 with the recesses 82, a further safeguard against rotation is formed, which has to be overcome for the removal of the filter element 14. Foot parts 34 projecting downwards from the lower end cap 24 are provided as a rotary aid for installation and removal of the filter element 14.

Claims

1. A filter device, having a filter housing (2) in which an exchangeable filter element (14) is accommodated, characterized in that the filter element (14) has a securing device (58) that can be inserted axially into a receiving device (20) of the filter housing (2), in that, after a rotational motion has been performed, snap means (70) are used to snap the securing device (58) to the receiving device (20) in a snap position.

2. The filter device according to claim 1, characterized in that in the snap position, while forming a lock, in particular against axial disassembly, contact surfaces (72, 74) of the securing device (58) and the receiving device (20) are in contact with each other when the device is not in operation.

3. The filter device according to claim 1, characterized in that at least one further pair of contact surfaces in the form of a guide surface (66) on the securing device (58) and a further guide surface (76) on the receiving device (20) secures the filter element (14) against its weight force by contact of the guide surfaces (66, 76) to each other during operation of the filter device under the fluid pressure produced.

4. The filter device according to claim 1, characterized in that the securing device (58) can be inserted into the receiving device (20) of the filter housing (2) against the force of an energy storage (62) acting on the filter element (14).

5. The filter device of claim 1, characterized in that the securing device is part of an end cap (22) of the filter element (14), wherein said securing device has securing bars (58) projecting axially from the end cap (22), wherein said securing bars (58) have the assignable snap means (70) and a part (72) of the contact surfaces (72, 74).

6. The filter device according to claim 1, characterized in that the snap means are formed of snap hooks (70) projecting radially beyond the axial orientation of the securing bars (58) and springing back and engaging with assignable snap recesses (82) in the receiving device (20) in the snap position.

7. The filter device according to claim 1, characterized in that the receiving device (20) has guideways (78) which, following a predeterminable course of curvature, guide the filter element (14) inserted axially into the filter housing (2), during its rotational motion until it reaches the snap position.

8. The filter device according to claim 1, characterized in that the guideways (78) each have an interruption (77) for a passage of an assignable snap-in hook each when the filter element is inserted axially.

9. The filter device according to claim 1, characterized in that at least part of the interruptions (77) have a control surface (80), which move the respective snap hook (70) into the snap position during the rotational motion for its further travel.

10. The filter device according to claim 1, characterized in that, during continued rotational motion after the respective snap hook (70) has been lifted out of the assigned interruption (77), the snap hook (70) passes over a further guide part (84) which, projecting radially outwards from a curved path, also supports the snap hooks (70) in their snap position.

11. The filter device according to claim 1, characterized in that the guide part (84) as a hollow box is integrally formed on the respective guideway (78), and in that the guide part (84) engages with a further third guide surface (90) in an axial spacing between the snap hook (70) and the contact surface (72) of the securing bar (58).

12. The filter device according to claim 1, characterized in that, when the rotational motion into the snap position of the filter element (14) in the assigned filter housing (2) is completed, the respective snap hook (70) engages with a recess (82) in the guideway (78) which adjoins the respective guide part (78) in the direction of rotation associated with this rotational motion.

13. The filter device according to claim 1, characterized in that the energy storage, formed as a compression spring (62), is a component of a bypass valve, the closing part (52) of which presses the filter element (14) in the opposite direction to its axial insertion motion.