Filter element

Abstract

1. Filter element 2. Filter element with an element material (22) which encloses a cavity (26), in particular in the form of a filtrate chamber, and which extends between two end caps (28, 30) which are arranged at the ends and which each have a sealing device (32, 34), wherein one sealing device (32) has a preferably polygonal opening cross section and the other sealing device (34) has a preferably circular opening cross section, and one sealing device (32) is part of a spherical bearing (44).

Description

[0001] Filterelement

[0002] The invention relates to a filter element with an element material that comprises a hollow space, in particular in the form of a filtrate chamber, and that extends between two end caps arranged at the ends, each having a sealing device. DE 10 2018 009 187 A1 discloses a filter device with a filter housing and a filter element received therein, the element material of which extends between two end caps, of which at least one end cap is mounted on an element receptacle by means of a spherical bearing that provides more than one degree of freedom so that the filter element is articulated to the element receptacle via its one end cap.This provides the possibility of compensating for possible misalignment errors, allowing a reduction in the tight tolerance limits to be maintained during production and thus enabling filter devices to be manufactured reliably and at low production costs, even with long filter elements or with assembled filter housings.

[0003] In the known solution, the filter element in the operating position is fixed in a defined manner with its lower end cap in a housing-side receptacle via a screw thread forming a seal and is guided longitudinally at its other, opposite end cap by means of an O-ring sealing ring along a nozzle-shaped element receptacle on the housing head of the filter housing.

[0004] Such filter devices and their filter elements are sometimes subjected to very heavy wear and tear in harsh everyday operation, for example, when such solutions are used in hydraulic hammer operations, where the filter element is regularly subjected to strong hydraulic pulsations. Because one end of the filter element is fixed in the housing via the thread in this known solution, the strong pulsations that occur, particularly during hammer operation, and the associated high differential forces on the filter element can seriously damage it.

[0005] Based on this prior art, the invention is therefore based on the object of further improving the known filter element solutions to enable trouble-free operation even under heavy loads on the filter element, particularly when hydraulic pressure pulsations occur. This object is achieved by a filter element having the features of patent claim 1 in its entirety.

[0006] Because, according to the characterizing part of patent claim 1, one sealing device has a preferably polygonal opening cross-section and the other sealing device has a preferably circular opening cross-section, and because one sealing device is part of a spherical bearing, any misalignment errors that may occur can still be compensated for via the spherical bearing. Furthermore, this creates inwardly "open" end caps on the element via the free opening cross-sections of the respective sealing device, which leads to a reduction in the pressure differential areas on the element, unlike in the known case where one end cap is open and the other end cap is closed. The open end cap design significantly minimizes any forces that may occur in the axial direction of the element, enabling failure-free operation even under high loads. This has no equivalent in the prior art.The different opening cross-sections, preferably one polygonal and one circular, prevent possible incorrect installation when replacing an element with a new one, as there is only one plausible installation option and, moreover, protection against plagiarism is implemented, both of which benefit reliable operation.

[0007] Particularly advantageously, the two sealing devices each have a sealing surface on the inner circumference, which, viewed in a fictitious projection parallel to the longitudinal axis of the filter element, are congruent with each other. This design further minimizes any potential pressure differential area, so that the forces occurring during operation cannot damage the filter element and, in particular, the element material.

[0008] In another particularly preferred embodiment of the filter element according to the invention, the spherical bearing comprises two shell parts, one of which is stationary on one end cap, and the other shell part, which has the sealing device, is pivotably mounted in the other shell part. In this way, even larger tolerance errors can be compensated for, and larger geometric deviations from one end cap to the other are possible, so that very tight manufacturing tolerances no longer have to be maintained, which helps reduce manufacturing costs.

[0009] In this embodiment, it is preferably provided that one sealing device has an annular groove on the outer circumference, into which the other shell part engages with an inner edge. This achieves a multi-part structure of spherical bearings with one sealing device, so that in the event of failure of the sealing device in question, it can be easily replaced with a new seal.

[0010] In a further preferred embodiment of the filter element according to the invention, one polygonal sealing device forms a regular polygon, preferably a square, on the inner circumference, so that between the thus formed and rounded corners, individual wall sections protrude convexly outward with the same curvature, and preferably the greatest curvature of one of the wall sections is smaller than the smallest curvature of one of the rounded corners. In this way, the polygonal sealing device is constructed with exceptionally stable properties and is capable of reliably absorbing forces in the radial transverse direction without compromising its sealing effect.

[0011] Preferably, this sealing device has a flat sealing surface on the inner circumference, which, viewed along the longitudinal axis of the filter element, opens out along bevels at the end. This creates a defined, central sealing surface that provides the seal without being over-determined in its sealing effect by other components of the sealing device.

[0012] In a further preferred embodiment of the filter element according to the invention, the other sealing device is formed from an O-ring, wherein this O-ring is preferably enclosed by sheet metal parts of the other end cap, in particular except for an exposed sealing surface. Accordingly, both sealing devices are designed such that they are guided longitudinally along guide parts, so that, depending on the pressure situation, the element can move along the guide parts into a suitable, largely force-free position.The invention further relates to a filter device for receiving a filter element as presented above, wherein a housing part of a filter housing, usually in the form of a filter head, accommodates a guide part with a cylindrical outer peripheral surface for engagement with one sealing device, and a further housing part, usually in the form of a filter bowl, which can be releasably connected to this housing part, accommodates a further guide part with a cylindrical outer peripheral surface for engagement with the further sealing device. In this way, an inherently stable positioning of the filter element relative to the housing parts of the filter device is achieved by means of the guide parts.

[0013] Preferably, one guide part is formed from a sleeve, along the outer side of which the one sealing device is guided longitudinally, and the other guide part is formed from a cup-shaped insert, which is designed as a locking part and can be locked to the other housing part, and whose outer circumferential surface forms a longitudinal guide for the other sealing device. Largely turbulence-free fluid flows for filtration with the filter element can be guided through the filter housing via this sleeve and the cup-shaped insert.

[0014] In the following, the solution according to the invention is explained in more detail using an exemplary embodiment according to the drawing. In a schematic representation and not to scale, the

[0015] Fig. 1 is a perspective view of a longitudinal section of a filter device;

[0016] Fig. 2, 3 the head and bottom area of ​​the filter device according to Fig. 1; Fig. 4 the spherical bearing arrangement of a filter element according to the

[0017] Fig. 1 and 2; and

[0018] Fig. 5 is a perspective view of a sealing device for the filter element in the area of ​​the spherical bearing according to Figs. 1, 2 and 4.

[0019] Fig. 1 shows a filter device as a whole in longitudinal section. The filter device according to Fig. 1 has a filter head 10 and a filter bowl 12, which is detachably screwed to the filter head 10 in a known manner. The filter device according to Fig. 1 is shown in its usual, vertical operating position, and the filter head 10 is permanently connected to a hydraulic supply circuit (not shown) in a stationary manner. Furthermore, the filter head 10 has an inlet 14 for an unfiltered stream and an outlet 16 for a filtrate stream. Both the inlet 14 and the outlet 16 are connected to the aforementioned hydraulic supply circuit in the usual way.A spring-loaded bypass valve 18 is connected between inlet 14 and outlet 16. This valve opens when a filter element in the filter device becomes clogged or blocked. It bypasses the filter element and directly connects the inlet 14 to the outlet 16, thus ensuring that the fluid flow within the supply circuit is not interrupted. This design is common for such filter devices, so it will not be discussed in more detail here.

[0020] Both filter head 10 and filter bowl 12 form components of a filter housing 20, in which the filter element is accommodated. The filter element is typically provided with an element material 22, which is preferably pleated to increase its filter surface. The element material 22 is supported on its inside by a perforated support tube 24 and thus comprises a cavity 26, which is also technically referred to as a filtrate chamber. Furthermore, the element material extends between two end caps 28, 30, each of which has a sealing device 32, 34.The filter element accommodated in the filter device is radially spaced from the inner peripheral side of the filter housing 20, so that the respective inner peripheral side and the outer peripheral side of the filter element together define an unfiltrate chamber 36 within the filter housing 20, which is connected to the inlet 14 in the direction of the filter head 10 via a channel-like fluid connection 38 in the filter head 10. The filtrate chamber 26, on the other hand, is connected to the outlet 16 for filtrate flow, with the further fluid connection 39 being routed past the bypass valve 18. Accordingly, the element material 22 is flowed through from the outside to the inside as viewed in the direction of Fig. 1, and any particulate contamination present in the fluid flow is reliably cleaned off the element material 22.

[0021] As Fig. 5 in particular shows, one sealing device 32 is designed with a polygonal opening cross-section 40 and, in particular according to the illustration in Fig. 3, the other sealing device 34 delimits a circular opening cross-section 42. As Fig. 4 further shows in particular, one sealing device 32 is part of a spherical bearing 44 for the filter element with its element material 22. As can be seen from Fig. 1, the two sealing devices 32, 34 each have an inner circumferential sealing surface 46, 48 which, viewed in a fictitious cylindrical projection parallel to the longitudinal axis of the filter element, are congruent with one another. In this way, effective differential pressure surfaces are minimized and a force-free bearing of the filter element within the filter housing 20 of the filter device is largely achieved.

[0022] As can be seen from Fig. 4, the spherical bearing 44 has two shell parts 50, 52, of which one shell part 50 is received in a stationary manner on one end cap 28, wherein the other shell part 52, which has the one sealing device 32, is pivotally received in one shell part 50. If the filter element with its spherical bearing 44 according to Fig. 4 is received in the filter head 10 along a sleeve 54, as can be seen in more detail from Fig. 2, the other shell part 52 is fixed in position relative to the filter head 10 in the radial direction, so that one shell part 50 can slide in an articulated manner with more than one degree of freedom along the convex outer peripheral side of the other shell part 52. In this respect, the convex outer peripheral surface of the other shell part 52 nestles against the correspondingly concave inner peripheral side of the one shell part 50.In this respect, the filter element with its element material 22 is then pivotably arranged on the other shell part 52 in different angular directions to the longitudinal axis of the filter element and can thus compensate for any misalignment errors that may occur.

[0023] One sealing device 32 has an annular groove 56 on its outer circumference, into which the other shell part 52 engages with a protruding inner edge 58, as shown in Fig. 4. The integrally formed end cap 28 has a sleeve-shaped boundary wall 60 at the bottom, which projects into the filtrate chamber 26 with a predeterminable projection, specifically at a predeterminable radial distance from the inner circumference of the support tube 24 in this area. In this respect, the end cap 28, with its cylindrical outer edge and the inner boundary wall 60, forms a trough-shaped receiving space for an adhesive bed 62 (not shown in detail), which serves to secure the end cap 28 to the free front ends of the element material 22 and the support tube 24.

[0024] As further shown in Figs. 4 and 5, the polygonal sealing device 32 forms a square with four corners 64 on the inner circumference, with individual wall sections 66 extending convexly outward between the thus formed and rounded corners 64 with the same curvature. The sealing ring with a polygonal opening cross-section has, on the inner circumference, formed from the corners 64 and the wall sections 66, a substantially planar, annular sealing surface 68, which, viewed at the end in the direction of the fictitious longitudinal axis of the filter element, opens out along bevels 70, 72. By means of the bevels 70, 72, the actual sealing surface 68 is "cut free" and thus forms a sliding surface in a sealing manner for sliding along the outer circumference of the head-side sleeve 54, which is particularly evident from the illustration in Fig. 2.

[0025] In this way, the upper end cap 28 is guided axially movable along the sleeve 54 via the spherical bearing 44 and the one sealing device 32 and is correspondingly supported in the radial direction. In this respect, the sleeve 54 is in any case received stationary in a head-side recess as part of the further fluid guide 39 in the filter head 10. In this respect, the sleeve 54 forms a guide part 74, along the outer side of which the one sealing device 32 is guided longitudinally movable. The other sealing device, as shown in Fig. 3, is formed from an elastomeric O-ring 76, which is chambered by sheet metal parts 78 of the other end cap 30, except for its inwardly exposed sealing surface 48.In this respect, the other end cap 30 in question is formed from a shaped sheet metal part and in turn has a sleeve part 80 which projects in the direction of the filtrate chamber 26 and which, together with the annular outer wall of the end cap 30, serves to receive a further adhesive bed 82 (not shown), with which the lower end regions of the element material 22 and the support tube 24 can be fixed in a defined manner to the other end cap 30. Also present in this lower end region of the filter element is a further guide part 84 which is formed from a cup-shaped insert 86 which, designed as a locking part, is locked at the bottom to the other housing part in the form of the filter bowl 12. The cup-shaped insert 86 in turn has a cylindrical, self-contained outer peripheral surface 88 on its outer circumference, which forms a longitudinal guide for the other sealing device 34 shown with the O-ring 76. As can be seen from Fig.1, on both opposite sides of the filter element, the latter is guided axially movable along the respective guide parts 74, 84 by means of the two sealing devices 32, 34, so that the filter element can position itself independently in a self-supporting manner depending on the pressurizing forces within the filter housing 20.

[0026] To prevent better oil drainage when emptying the filter bowl 12, the additional guide part 84 has circular recesses 85 on the bottom side; however, since the pot-like additional guide part 84 is designed to be closed in the direction of the filtrate chamber 26, no unfiltered material can reach the filtrate side in this area, unless the unfiltered material flows through the element material 22 of the filter element and passes through the support tube 24, which represents the usual filter operation.

[0027] The solution according to the invention also readily permits its use in so-called hammer operation, in which the filter element is subjected to heavy hydraulic loads due to pulsations. The fact that two open end caps 28, 30 are present on the filter element makes it possible to significantly minimize the effective pressure differential area and thus the force in the axial direction. For this purpose, both end caps 28, 30 must be reliably sealed, which is readily possible using the aforementioned sealing devices 32, 34. Since one sealing device 32 is clipped to the spherical bearing 44 of one end cap 28 and the O-ring 76 of the other sealing device 34 is guided in sheet metal parts 78 of the other end cap 30, the sealing devices 32, 34 do not need to be glued, which simplifies and reduces the cost of manufacturing the filter element.

Claims

Patent claims 1. Filter element with an element material (22) comprising a cavity (26), in particular in the form of a filtrate space, and extending between two end caps (28, 30) arranged at the ends, each having a sealing device (32, 34), characterized in that one sealing device (32) has a preferably polygonal and the other sealing device (34) has a preferably circular opening cross-section, and that one sealing device (32) is part of a spherical bearing (44).

2. Filter element according to claim 1, characterized in that the two sealing devices (32, 34) each have an inner circumferential sealing surface (46, 48) which are congruent with each other in a fictitious projection parallel to the longitudinal axis of the filter element.

3. Filter element according to claim 1 or 2, characterized in that the spherical bearing (44) has two shell parts (50, 52), one of which shell part (50) is stationary on one end cap (28) and the other shell part (52), which has one sealing device (32), is pivotably mounted in one shell part (50).

4. Filter element according to one of the preceding claims, characterized in that one sealing device (32) has an annular groove (56) on its outer circumference, into which the other shell part (52) engages with an inner edge (58). A filter element according to one of the preceding claims, characterized in that one polygonal sealing device (32) forms a regular polygon, preferably a square, on its inner circumference; that between the corner points (64) formed in this way and which are rounded, individual wall sections (66) project convexly outwards with the same curvature; and that preferably the greatest curvature of one of the wall sections (66) is smaller than the least curvature of one of the rounded corner points (64). A filter element according to one of the preceding claims, characterized in that one sealing device (32) has a planar sealing surface (68) on its inner circumference, which opens at its end along inclined planes (70, 72) when viewed in the direction of the longitudinal axis of the filter element. A filter element according to one of the preceding claims, characterized in that the other sealing device (34) is formed from an O-ring (76).Filter element according to one of the preceding claims, characterized in that the O-ring (76) is chambered by sheet metal parts (78) of the other end cap (30), in particular extending to an exposed sealing surface (48). Filter device for receiving a filter element according to one of the preceding claims, characterized in that a guide part (74) with a cylindrical outer circumferential surface for contact with one sealing device (32) is received in a housing part (10) of a filter housing (20), and a further guide part (84) with a cylindrical outer circumferential surface for contact with the other sealing device (34) is received in a further housing part (12) that is detachably connectable to this housing part (10). Filter device according to claim 9, characterized in that one guide part (74) is formed from a sleeve (54) along the outside of which one sealing device (32) is longitudinally movably guided and that the other guide part (84) is formed from a cup-shaped insert (86) which is designed as a detent part with the other Housing part (12) can be locked in place, and its outer circumferential surface (88) forms a longitudinal guide for the other sealing device (34).

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