Patent ID: 12208353

DETAILED DESCRIPTION

The figures show merely examples and are not intended to be limiting. Similar or equal elements are referred to with same reference numerals in the Figures.

FIG.1shows a longitudinal cut view of a filter system100according to an embodiment of the invention.FIG.2shows the filter system100ofFIG.1in an exploded view.

The filter system100comprises a housing110, a fluid inlet102formed in a housing wall112, a fluid outlet108formed in a bottom housing wall120. In this embodiment, the housing110may consist of three segments, the bottom housing wall120, the intermediate ring-shaped housing wall112with the fluid inlet102and a cover part114. The segments are connected to each other by, e.g., clamps, screws or the like. A hollow cylindrical primary filter element50is accommodated in the housing110. For removing the primary filter element50for maintenance or exchange the housing walls112,114can be removed from the bottom housing wall120together in one piece or only the cover part114is removed.

The body of the primary filter element50is made of a filter medium56which may be pleated, for instance. The primary filter element50is covered at both ends by ring shaped first and second end caps52,54, which are made, for example, from polyurethane which is well known in the prior art. Sealing structures and supporting ribs are arranged at the exterior sides of the first end cap42and the second end cap54. The primary filter element50is clamped between the bottom housing wall120and the cover housing wall114in a sealing tight manner so that a fluid has to pass through the primary filter element50in a radial direction, which is indicated by bold arrows inFIG.1. The second end cap54of the primary filter element50is configured to have a feedthrough for the stand pipe150and is accommodated in the bottom housing wall120which is provided with a groove126. For radial fixation of the primary filter element50, a ring shaped projection128is arranged in the groove126.

In its front face130, the cover part114is provided with a recess138which extends into the interior of the housing110.

Inside the primary filter element50, a secondary filter element10is arranged. The primary and secondary filter elements50,10are arranged concentrically about an axis extending in a longitudinal direction L, referred to as longitudinal axis L. The secondary filter element10is arranged downstream the primary filter element50so that fluid has to pass through the secondary filter element10on its way to the fluid outlet108. The secondary filter element10is arranged on a stand pipe150which is rigidly connected to the bottom housing wall120. The lower part of the stand pipe150merges with the fluid outlet108of the bottom housing wall120. The secondary filter element10comprises a filter medium16forming a body36with at least one weld seam18along the longitudinal direction L.

Optionally, the secondary filter element10comprises a closed end cap20at its top region12, wherein the secondary filter element10and the stand pipe150are mutually connected at their top regions12,152by connection elements. The open ended side of the secondary filter element10is accommodated in a circular groove122in the bottom wall120.

The first end cap52at the top region of the primary filter element50is provided with a protrusion element58extending in axial direction towards the top region12of the secondary filter element10.

The bottom region55of the primary filter element50and the housing wall120accommodating the stand pipe150are configured with mutual self-positioning elements62,92to arrange the primary filter element50on the housing wall120in a defined rotational position with respect to one or more struts170of the stand pipe150. The struts170are arranged about the longitudinal axis L and are pointing to the interior of the stand pipe150.

In particular, a radially extending protrusion64is arranged at the bottom part55of the primary filter element50as self-positioning element62. A guiding surface94is arranged around the stand pipe150as self-positioning element92. The guiding surface94is formed as a ramp which has a maximum region with a maximum height in relation to the longitudinal axis L and a minimum region with a minimum height in relation to the longitudinal axis L at the opposite side of the stand pipe150. The radially extending protrusion64can glide on the guiding surface94from the maximum region to the minimum region when the primary filter element50and/or the bottom housing wall120are rotated about the longitudinal axis L. A notch96is arranged in the minimum region in which the radially extending protrusion64of the primary filter element50can snap into place.

FIG.3shows a first embodiment of a secondary filter element10with an end cap20at its top region12having a recess24at its exterior side.FIG.4shows a bottom wall120of a housing110of a filter system100with a stand pipe150rigidly attached to the bottom wall120to which the secondary filter element10ofFIG.3can be attached.

FIG.3shows a first embodiment of a secondary filter element10with an end cap20having a recess24at its exterior side. The secondary filter element10has a body36consisting of a filter medium16. The filter medium16can be a nonwoven material, paper, cellulose or a mixed fiber of plastic and cellulose. The filter medium16can be designed endlessly on the circumference of the secondary filter element10with at least one longitudinal weld seam18. The filter body36formed thereof has a conical shape with a large diameter at a bottom region14and a smaller diameter at the top region12of the body36where the end cap20is mounted. Preferably the filter medium16is connected to the end cap20by way of a circumferential weld seam28. The recess24in the end cap20extends into the interior of the body36.

FIG.4shows a bottom wall120of a housing110of a filter system100with a stand pipe150attached to the bottom wall120. The lattice-like body of the stand pipe150is conically shaped and composed of longitudinal struts170and circumferential struts172, only two of each are referred to with reference numerals and reference lines for clarity reasons.

The stand pipe150is provided as a carrier of the secondary filter element10as shown inFIG.4. The secondary filter element10and the stand pipe150each comprise complementary connecting means with which they can be connected to one another at one of their end faces, shown on top of the secondary filter element10and the stand pipe150in theFIGS.3and4. This allows for a safe and stable assembly of both the primary filter element50(FIGS.1,2) and the secondary filter element10, as well as a very economical interchangeability of the primary filter element50and, if appropriate, of the secondary filter element10in the event of maintenance. The secondary filter element10rests firmly on the stand pipe150. Due to the closed end cap20of the secondary filter element10, even with dismounted primary filter element50the clean side of the filter system100is protected against particulate matter even if fluid is still sucked through the secondary filter element10.

The stand pipe150in this embodiment comprises a receptacle160at its top region152. The contour of the receptacle160corresponds to the exterior contour of the endcap20of the secondary filter element10. The receptacle160has an open ended bottom which ends in a connection element156for the connection elements (not shown) of the secondary filter element10. For instance, snap beams can be hooked on the bottom of the receptacle160as locking element and establish a snap fit connection between the stand pipe150and the secondary filter element10. The receptacle160is funnel shaped in its bottom region so that introducing the snap beams is facilitated.

FIGS.5and6illustrate a bottom housing wall120according to an embodiment of the invention.FIG.5shows a side view of the housing wall120with a rigidly attached stand pipe150.FIG.6shows a cut view of the housing wall120according toFIG.5rotated by 90° about a longitudinal axis L. The interior of the stand pipe150is in fluid connection with the fluid outlet108.

The stand pipe150is surrounded by a self-positioning element92being configured as guiding surface94having the shape of a ring ramp. The guiding surface94is formed as a ramp which has a maximum region with a maximum height in relation to the longitudinal axis L and a minimum region with a minimum height in relation to the longitudinal axis L at the opposite side of the stand pipe150. A radially extending protrusion64(FIGS.1and2) can glide on the guiding surface94from the maximum region to the minimum region when the primary filter element50and/or the bottom housing wall120are rotated about the longitudinal axis L. A notch96is arranged in the minimum region in which the radially extending protrusion64of the primary filter element50can snap into place.

FIG.7shows a primary filter element50according to an embodiment of the invention comprising a radially extending protrusion64at the outer circumference of the second end cap54.FIG.8shows a ring60for accommodating the filter medium56of the primary filter element10comprising a radially extending protrusion64at the outer circumference of its second end cap54. The primary filter element50has a filter body consisting of a filter medium56which extends between a first end cap52and a second end cap54which has a feedthrough for the stand pipe150(FIGS.5and6). The filter medium56is attached to the outer surface of a support structure70arranged in the interior of the primary filter element50. A self-positioning element62configured as a radially extending protrusion64is arranged at the second end cap54. The radially extending protrusion64is part of a ring60which is embedded in the material of the second end cap54. The ring60is shown inFIG.8. The ring60accommodates the filter body consisting of the filter medium56in its interior. The ring60has an outer rim which overlaps the bottom part of the filter body in axial direction.

FIGS.9and10show side views of a primary filter element50mounted to a housing wall120in two rotational positions distinct by 90° relative to the longitudinal axis L. InFIG.9, the guiding surface94is inclined from the maximum region on the right side of the primary filter element50to the minimum region on the left side of the primary filter element50. InFIG.10, the minimum region with the notch96is seen as front view. The radially extending protrusion64is snapped into the notch96and secures the rotational position of the primary filter element50in the bottom housing wall120.

FIGS.11and12illustrate in cut views how the primary filter element50according toFIG.9is introduced in the bottom housing wall120.FIG.11shows a cut view of the primary filter element50in a state where the primary filter element50is mounted to the housing wall120accommodating the stand pipe150. The radially extending protrusion64is seen on the left side of the drawing where it contacts the maximum region of the guiding surface94.

FIG.12shows a cut view of the primary filter element50according toFIG.11where the primary filter element50is arranged at the housing wall120in its final, rotationally defined position with respect to struts170of the stand pipe150. The primary filter element50has been turned by 180° about the longitudinal axis L and the radially extending protrusion64rests in the notch96of the guiding surface94.

FIG.13shows an embodiment of a secondary filter element10which is mounted to a stand pipe150before the secondary filter element10is in its final position. To mount the secondary filter element10onto the stand pipe150, the body36of the secondary filter element10is put over and moved along the stand pipe150until the end cap20comes close the receptacle160of the stand pipe150.

The end cap20enters the receptacle160towards the funnel-shaped bottom region of the receptacle160with the snap beams23first. The end cap20can be introduced into the receptacle160until the projection element32hits the guiding surface182. The longitudinal extension90of the projection element32is smaller than the depth168of the top segment162of the receptacle160. Thus, the upper segment21of the end cap20can be immersed partly into the top segment162so that the step25is safely inside the receptacle160. As a result, the end cap20can be guided further into the receptacle160safely without tilting.

The guiding surface182has one maximum point190in the bottom segment164of the receptacle160and is inclined on both sides of the maximum point190. The maximum point190of the guiding surface182is at the interface between the top segment162and the bottom segment164of the receptacle160. By turning the end cap20in either direction about the longitudinal axis L the end cap20moves further into the receptacle160because the projection element32is guided on the guiding surface182until the projection element32reaches the pocket186in the guiding surface182.

The end cap20now is moved axially until the projection element32is accommodated in the pocket186. As the snap beams23move axially downward, too, they can snap over the rim of the funnel shaped bottom segment164. The rim is the locking element157of the stand pipe150. The snap beams23lock the end cap20safely to the stand pipe150. The end cap20may be removed from the stand pipe150by an opposite sequence of movement by pulling and turning the end cap20.

For turning the end cap20, a tool such as a handle or the like can be applied to the recess24of the end cap20.

With the projection element32accommodated in the pocket186, the secondary filter element10is positioned accurately in a well-defined rotational position with respect to the stand pipe150. Hence, the longitudinal weld seam (not shown) is in a distinct position with respect to the longitudinal struts170of the stand pipe150and, consequently, to a mass flow sensor arranged at a fixed position close to the filter elements. Preferably, the hooks at the snap beams23are provided with inclined surfaces so that these can come loose when some force is applied to the end cap20.

The length of the end cap20with snap beams23is matched to the depth of the receptacle160so that the snap beams23come into contact with the rim, i.e. the locking element157, of the funnel shaped end of the receptacle160with the projection element32reaching its end position in the pocket186. The step25of the end cap20rests on the maximum point190of the guiding surface182in the receptacle160.