Filter device

A filter device has a filter housing (2, 4) accommodating a filter element (16) separating an unfiltered substance chamber (26) from a filtrate chamber (20) within the filter housing (2, 4). The filter element (16) is sealed against the filter housing (2, 4) by a sealing device (36, 40). The filter element (16) is mounted inside the filter housing (2, 4) using movable bearings (32, 38).

FIELD OF THE INVENTION

The invention concerns a filter device comprising a filter housing, which holds a filter element that separates an unfiltrate chamber from a filtrate chamber inside the filter housing. The filter element is sealed against the filter housing by a sealing device.

BACKGROUND OF THE INVENTION

Filter devices of this kind (DE 10 2007 046 208 A1) are prior art, are available in the most diverse designs, different dimensions, filter characteristics and other specifications, and are used in many applications for the filtration of fluids of all kinds. When used to filter operating fluids in engineering equipment, for example hydraulic fluids, fuel or lubricants, cooling liquids and the like, the filter devices are often installed in locations where they are subjected to vibrational loads in operation. This environment is the case when filter devices are used in mobile machinery such as excavators, front-end loaders, mobile cranes, forklifts and the like. Vibrations that act on the filter element can cause the destabilization of the respective filter medium, which causes a reduction in filter performance.

SUMMARY OF THE INVENTION

In this respect, an object of the invention to provide an improved filter device that is characterized by an increased resistance to reduced effectiveness caused by vibrations.

This object is basically met according to the invention by a filter device having, as one significant feature of the invention, a filter element supported inside the filter housing solely by floating bearings. The combination of a partially moveable support allows for a vibration-dampened retention of the filter element, and thus, an improvement in operational reliability of a filter device that is subjected to vibrational loads.

A particularly effective vibration damping effect can be achieved through the support if the bearings act mainly in vertical directions with respect to each other. When the device is in operation, a first floating bearing acts mainly in horizontal, radial direction and a second floating bearing acts in vertical, axial direction.

In a particularly advantageous manner, the respective bearing may be provided with a sealing ring of the sealing device. By the sealing ring, the filter element is sealed against the filter housing.

Particularly favourable conditions concerning the damping of vibrations are obtained if the respective sealing ring that forms part of the bearing is elastically flexible, preferably of an elastomeric material.

In particularly advantageous exemplary embodiments, the sealing ring that forms part of the first floating bearing is disposed between a connection point of the filter element and a head of the filter housing. The sealing ring that forms part of the second floating bearing is disposed between the filter head and a filter bowl of the filter housing. Thus, in the overall connection between filter element and filter bowl of the housing, which connection is obtained through the floating bearing between the filter element and the filter housing head and through the fixed bearing between the filter housing head and the filter housing bowl, an elastomeric bearing element each is provided for achieving an effective vibration damping effect by the formed support.

In particularly advantageous exemplary embodiments, the one end cap of the filter element, which end cap forms the connection point, is provided with a support surface that overlaps the filter bowl. The support surface compresses, with increasing connection between filter head and filter bowl, the bearing-sealing ring, which acts primarily in vertical direction, against a further support surface in such a way that the sealing ring widens in radial direction. The elastomeric, compressed sealing ring then forms a pre-tensioned damping element between the support surfaces of the fixed bearing.

In a particularly advantageous manner, the further support surface for the bearing-sealing ring that forms the second floating bearing is made as part of the filter bowl and that the one support surface forms a closed external circumference ring. The closed external circumference ring is attached via connecting webs to the other parts of the end cap and is provided with a shoulder at the outer circumference above the second floating bearing. The shoulder at the outer circumference ring of the end cap facilitates the compression of the sealing ring of the second floating bearing.

The sealing ring that forms part of the first floating bearing may be located in a circumferential groove of a cylindrical extension of the end cap, which delimits the connection point and may be brought in contact with a cylindrical connection part of the filter head. The floating bearing then forms simultaneously a seal of the fluid passage between the connection point of the end cap and the internal cavity of the filter element into which the cylindrical extension protrudes and that forms, for example, the unfiltrate side in the filtering process.

To achieve particularly good damping characteristics, the diameter of the sealing ring that co-forms the first floating bearing is preferably smaller than the diameter of the sealing ring that co-forms the second floating bearing, where both bearings are located at a distance from each other in axial direction so that the filter element is supported essentially free of vibrations inside the filter housing.

An object of the invention is also a filter element that is provided in particular for use in a filter device according to the invention. The filter element comprises a filter material that extends between two end caps, where at least one of the end caps of the filter element is provided with receptacles for the components of two bearings. The working direction of the two bearings extends essentially vertical to each other.

Other objects, advantages and salient features of the present invention will become apparent from the following detailed description, which, taken in conjunction with the drawings, discloses a preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The exemplary embodiment of the filter device according to the invention shown in the drawings comprises a filter housing in form of a circular, cylinder-shaped filter bowl2. The drawings only depict the section of the filter bowl upper, open end. The filter bowl has a closed bowl bottom (not shown). The filter bowl2may be closed at the upper end by a filter head4that forms an end cap. The end cap overlaps with a skirt-shaped, axially protruding collar6over an annular body8of the housing bowl2. The annular body8forms a radial projection on the filter bowl2. To facilitate the attachment of the filter head4to the filter bowl2, a thread10is formed between the collar6of the filter head4and the annular body8of filter bowl2. A fluid inlet12, arranged coaxial to the cylinder or longitudinal axis100, is disposed at the upper end of the filter head4for the supply of unfiltrate. A fluid outlet14is provided, radially offset from the fluid inlet, for the filtrate discharge.

The filter element16, which may be inserted into the filter bowl2, comprises a hollow, cylinder-shaped filter medium18that is bounded at each end by an end cap, as is usual with filter elements of this kind. The drawings only show the upper end cap22that is assigned to the filter head4. For the purpose of forming a connection point through which the filter element16can be connected to the fluid inlet12, the end cap22is provided with a coaxial, cylindrical extension24. Extension24forms the fluid passage from the filter head4, attached to filter bowl2, from the fluid inlet12to the internal filter cavity26surrounded by the filter medium18. From the filter cavity26, which forms the unfiltrate chamber in operation, the fluid flows, after flowing through the filter medium18, into the filtrate chamber20located on the outside of the filter cavity26, and from there to the fluid outlet14of the filter head.

To provide a sealed connection between the extension24of the end cap22, which forms the connection point, and the fluid inlet12, the filter head4is provided with a cylindrical connector28. Connector28cups the edge30of the extension24when the filter head4is attached to filter bowl2. A first support point is provided between the edge30and the connector28in form of a first floating bearing32to support the filter element16. This bearing is called a “floating bearing” because this support point provides support in horizontal, radial direction, relative to longitudinal axis100, but has no support surfaces that act in the vertical, axial direction along longitudinal axis100. To describe it more accurately, the floating bearing32comprises a circumferential groove34in the vicinity of the top edge30of the extension24of the end cap32, where a sealing ring36is radially compressed between the base of the groove34and the inside of the cylindrical connector28of the filter head4. The first floating bearing32then forms via the sealing ring36not only the sealing function of the filter element16, but also provides support in horizontal direction.

The filter element16is supported on filter head4, which is attached to the filter housing head, via a second support point in form of a second floating bearing38. Like the first floating bearing32, the second bearing38comprises a sealing ring40as a bearing component, so that the bearing38simultaneously provides a sealing function. The bearing point that comprises the sealing ring40is called a “floating bearing” because, when the filter head4is attached to the filter bowl2, that is, when screwing the filter head4tight, the sealing ring40is compressed in vertical direction only by the weight of the filter element16between a first support surface42, which is provided on the upper end cap22, and a second support surface44. The first support surface42is located on an external circumference or cap ring46, which surrounds the main part of the upper end cap22as a closed annual body at a radial distance and is attached to the main part via radially extending connecting webs48. To facilitate the vertical, axial compressing of the sealing ring40, the circumference ring46is provided with a shoulder50in form of a radially protruding annular rib that forms the first support surface42. First support surface42compresses the sealing ring40against the further or second support surface44through the weight of the filter element16. The further support surface44is located on an annular rib54that protrudes radially from the filter housing bowl2. Due to the axial compression the sealing ring40is widened in radial direction and then forms not only a seal, but also a support. Sealing ring40seals in radial direction between filter housing bowl2and filter housing head4. In other words, this forms a seal of the filtrate chamber20towards the outside of the filter housing.

Due to the fact that two support points are disposed at an axial distance from each other formed by the two floating bearings32,38and enable relative movements in axial direction, and because floating bearing32as well as floating bearing38comprise, as support elements, elastomeric sealing rings36and40, respectively, the filter element support as a whole has an overall vibration damping effect and provides for a reliable operation of the filter element16when vibration loads occur in operation. Because the filter element16may move axially, counter to the force of the weight, the internal boundary surface56of the connector28of the head4, which adjoins fluid inlet12, forms an end-stop surface for the rim30of the extension24of the end cap22. Axial movements are then limited to an amount at which the circumferential ring46of the end cap22still remains in a position in which it cups the rim58of the filter bowl2. As a result of the floating bearings, the filter element is supported in the filter housing in a “floating” manner and is able to adjust itself correspondingly in vertical orientation when the entire filter device is installed in a normal position. In particular, during filtration, it will find its own sealing position due to the fluid pressure.