SECONDARY FILTER ELEMENT AND FILTER SYSTEM

Abstract

A secondary filter element for filtering a gaseous fluid and for self-cleaning a filter system of an intake air filter system for a motor has a filter medium which in operation is flowed through by the gaseous fluid from an inflow side to an outflow side. The secondary filter element has a central tube surrounding a longitudinal axis. The central tube has an open end and a circumferentially closed region adjacent the open end having an axial length. The secondary filter element further has a support element covering the filter medium at the inflow side. An impact point of a pressure pulse of a purging medium is arranged on the axial length of the circumferentially closed region. A filter system with the secondary filter element and a purging device for emitting the pressure pulse of the purging medium is provided.

Claims

1. A secondary filter element, comprising: a central tube surrounding a longitudinal axis and having an open end, the central tube comprising a circumferentially closed region adjacent the open end having an axial length; a filter medium arranged on a radially outer side of the central tube and configured for a gaseous fluid to flow from a radially outer side of the filter medium to a radially inner side of the filter medium; and a support element arranged at the radially outer side of the filter medium and having a plurality of flow-through openings; wherein the circumferentially closed region covers at least one impact point of a pressure pulse applied by a purging device; and wherein the at least one impact point is arranged on the axial length of the circumferentially closed region between the filter medium and the open end of the central tube.

2. The secondary filter element according to claim 1, wherein the filter medium is configured to be flowed through by the gaseous fluid from an inflow side of the filter medium to an outflow side of the filter medium.

3. The secondary filter element according to claim 1, wherein the support element is a grid and/or a perforated sheet.

4. The secondary filter element according to claim 1, wherein the support element is comprised of a plastic material.

5. The secondary filter element according to claim 4, wherein the plastic material comprises polyethylene.

6. The secondary filter element according to claim 5, wherein the polyethylene is a high-density polyethylene.

7. The secondary filter element according to claim 1, wherein the support element comprises a proportion of an open surface provided for flow therethrough to a closed surface of at most 85%.

8. The secondary filter element according to claim 7, wherein the proportion of the open surface provided for flow therethrough to the closed surface is at most 70%.

9. The secondary filter element according to claim 8, wherein the proportion of the open surface provided for flow therethrough to the closed surface is at most 60%.

10. The secondary filter element according to claim 1, wherein the support element is fixedly connected to the filter medium at the radially outer side of the filter medium.

11. The secondary filter element according to claim 10, wherein the support element is fixedly connected to an end disk of the filter medium.

12. The secondary filter element according to claim 2, wherein the support element is configured to be placed onto the inflow side of the filter medium at the radially outer side of the filter medium.

13. The secondary filter element according to claim 12, wherein the support element is arranged in a hollow cylinder shape about the filter medium at the inflow side of the filter element.

14. The secondary filter element according to claim 12, wherein the support element is a flat material placed around the filter medium at the inflow side of the filter medium and connected along a seam.

15. The secondary filter element according to claim 1, wherein the pressure pulse of the purging device originates at the open end of the central tube and impacts the impact point on the axial length of the circumferentially closed region of the central tube at a slant angle to the longitudinal axis.

16. A filter system for filtering a gaseous fluid and for pressure pulse cleaning, the filter system comprising: a primary filter element having a clean side and a raw side; a secondary filter element arranged at the clean side of the primary filter element, the secondary filter element comprising: a central tube surrounding a longitudinal axis of the filter system and having an open end, the central tube comprising a circumferentially closed region adjacent the open end having an axial length; a filter medium configured for flow-through by the gaseous fluid from an inflow side to an outflow side; and a support element covering the filter medium at the inflow side; a purging device configured to emit a pressure pulse of a purging medium from the clean side of the primary filter element to the raw side of the primary filter element; wherein at least one impact point of the pressure pulse of the purging medium is arranged on the axial length of the circumferentially closed region between the filter medium of the secondary filter element and the open end of the central tube of the secondary filter element.

17. The filter system according to claim 16, wherein the pressure pulse of the purging medium originates at the open end of the central tube and impacts the impact point arranged on the axial length of the circumferentially closed region of the central tube at a slant angle to the longitudinal axis.

18. The filter system according to claim 16, wherein the purging device comprises a purging pipe having a cone shaped diffuser adjacent an outlet end of the purging pipe.

19. The filter system according to claim 18, wherein the cone shaped diffuser is configured to direct the pressure pulse of the purging medium emitted by the purging device onto the at least one impact point arranged on the axial length of the circumferentially closed region of the central tube of the secondary filter element.

20. The filter system according to claim 16, wherein the support element of the secondary filter element has a plurality of flow-through openings and a proportion of an open surface of the support element provided by the flow-through openings to a closed surface of the support element is at most 85%, such that the support element covers and closes off at least 15% of a flow area of the inflow side of the filter medium of the secondary filter element to support the filter medium against the pressure pulse of the purging medium emitted by the purging device.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Further advantages result from the following drawing description. In the drawings, embodiments of the invention are illustrated. The drawings, the description, and the appended claims contain numerous features in combination. A person of skill in the art will consider the features expediently also individually and combine them to expedient further combinations.

[0030] The drawings show embodiments in an exemplary fashion.

[0031] FIG. 1 shows a side view of a filter system for filtering a gaseous fluid, for example for a self-cleaning intake air filter system of a motor, according to an embodiment of the invention.

[0032] FIG. 2 shows a longitudinal section through the filter system according to FIG. 1.

[0033] FIG. 3 shows an isometric view of a secondary filter element according to an embodiment of the invention.

[0034] FIG. 4 shows a longitudinal section of the secondary filter element according to FIG. 3 without support element.

[0035] FIG. 5 shows an isometric view of a secondary filter element according to a further embodiment of the invention.

[0036] FIG. 6 shows a longitudinal section of the secondary filter element according to FIG. 5 without support element.

DETAILED DESCRIPTION

[0037] In the drawing figures, same or similar type components are identified with like reference characters. The drawing figures show only examples and are not to be understood as limiting.

[0038] Directional terminology used in the following with terms like left, right, top, bottom, in front of, behind, downstream and the like serve only for better understanding of the drawing figures and are not to be understood in any way as a limitation. The illustrated components and elements, their configuration and use may vary in the sense of considerations of a person of skill in the art and may be adapted to the respective applications.

[0039] FIG. 1 shows a side view of a filter system 100 for filtering a gaseous fluid, for example for a self-cleaning intake air filter system of a motor, according to an embodiment of the invention, while in FIG. 2 a longitudinal section of the filter system 100 is illustrated.

[0040] The filter system 100 comprises a hollow cylinder-shaped primary filter element 40 which in the intended operation is flowed through from a radially outer side 42 to an inner side 44 by the fluid to be purified. The primary filter element 40 comprises a filter body 46 that is closed at both ends by a respective end disk 48, 49. The primary filter element 40 is clamped with the end disks 48, 49 against the filter housing 110 which is comprised of a housing top part 112 and a housing bottom part 114. By means of the end disks 48, 49, the raw side 50 is also sealed against the clean side 52 of the filter system 100.

[0041] The secondary filter element 10 is arranged at the inner side 44 of the primary filter element 40 and thus at the clean side 52. The secondary filter element 10 comprises a filter medium 12, for example, a nonwoven layer, and is flowed through by the fluid in the intended operation from an inflow side 20 to an outflow side 22.

[0042] The filter medium 12 is arranged on a radially outer side 18 of a hollow cylinder-shaped central tube 14 along a longitudinal axis L. In the intended operation in the filter system 100, the radially outer side 24 of the filter medium 12 is embodied in this context as inflow side 20. The filter medium 12, which is embodied, for example, as a nonwoven, is wound about the central tube 14 and welded.

[0043] In order to be able to clean off deposits at the raw side 50 from the filter body 46 of the primary filter element 40 in the filter system 100 with self-cleaning action, also referred to as back-washing, the filter system 100 may be provided with a purging device 116 with which a purging medium, for example, a purging gas, is introduced at the clean side 52 via an outlet socket 124 of the filter system 100 into the inwardly positioned flow chamber, wherein the purging medium flows through the wall of the filter body 46 from the clean side 52 to the raw side 50 and detaches deposits at the raw side 50 by means of a pressure pulse.

[0044] The illustrated filter system 100 is of a self-cleaning embodiment and comprises a purging device 116 which is embodied for temporary emission of a pressure pulse of a purging gas as purging medium from the clean side 52 to the raw side 50.

[0045] The cleaning device 116 comprises a pipe elbow 118 that is projecting through an opening in the wall of the outflow socket 124 and is connected to the outlet socket 124.

[0046] The filter system 100 may comprise a plurality of purging devices 116 that are distributed about the circumference of the outflow socket 124.

[0047] The filter medium 12 is covered at the intended inflow side 20 by a support element 16 in order to protect the filter medium 12 in this way against the pressure pulse of the purging gas and to prevent bulging of the filter medium 12 or even a damage of the filter medium 12.

[0048] For this purpose, the support element 16 is embodied in a hollow cylinder shape about the filter medium 20 arranged on the central tube 14 at the inflow side 20.

[0049] The filter housing 110 of the filter system 100 comprises an inflow guard 122 arranged radially about the primary filter element 40 which imparts a swirl flow to the fluid flowing in through the inlet 102 and shields the filter body 46 against flow pressure of the fluid. Due to the swirl flow, large dirt particles may deposit in the filter housing 110 and may be suitably discharged.

[0050] FIG. 3 shows an isometric view of the secondary filter element 10 according to an embodiment of the invention, while in FIG. 4 a longitudinal section of the secondary filter element 10 without support element 16 is illustrated.

[0051] The support element 16, which is arranged in the form of a hollow cylinder about the secondary filter element 10, may be embodied as a grid, as illustrated in the embodiment shown in FIG. 3. Alternatively, it is also possible that the support element 16 is configured as a perforated sheet.

[0052] The support element 16 is for example embodied of a plastic material. In this context, for example polyethylene, for example high-density polyethylene (HDPE), may be used.

[0053] The support element 16 may be provided with a proportion of an open surface for flow therethrough to a closed surface of at most 85%, for example at most 70%, for example at most 60%, in order to provide a beneficial stabilization of the filter medium 12 against the pressure pulse of the purging gas of the purging device. With the indicated surface ratios, despite the stabilizing action of the support element 16, a satisfactory permeability for the fluid to be filtered and the purging gas may be realized so that a predetermined maximum pressure loss for the fluid to be filtered through the filter system 100 may be observed.

[0054] The support element 16 may be fixedly connected to the filter medium 12. For example, the support element 16 may be fixedly connected to an end disk 28 of the filter medium 12, as illustrated in FIG. 3. In this context, the support element 16 may be expediently embedded by foaming when producing the end disk 28.

[0055] In an alternative embodiment, the support element 16 may be placed or pushed onto the inflow side 20 of the filter medium 12 and, for example, may be connected, for example, glued, at the rims to the filter medium 12. The support element 16 may thus be placed as a flat material about the filter medium 12 at the inflow side 20 and may be connected along a seam, for example, welded.

[0056] FIG. 5 shows an isometric view of a secondary filter element 10 according to a further embodiment of the invention, while in FIG. 6 a longitudinal section through the secondary filter element 10 according to FIG. 5 without a support element is illustrated.

[0057] The embodiment of the secondary filter element 10 illustrated in FIGS. 5 and 6 deviates from the embodiment illustrated in FIGS. 3 and 4 in that, adjacent to the open end 26 of the central tube 14, as may be best seen in FIG. 6, a closed region 30 with an axial length 32 is formed on a circumference immediately adjoining the open end 26. In this context, the length 32 of the region 30 is selected such that at least one impact point of the pressure pulse of the purging medium of the purging device 116 that is impacting, originating from the open end 26, at a slant to the longitudinal axis L on the central tube 14 is covered, upon use in the filter system 100 (see FIG. 2). In this way, it may be prevented that the relatively hard pressure pulse of the purging gas impacts directly through the central tube 14 on the filter medium 12 and possibly damages it. In an alternative embodiment, the region 30 could also be designed as a ring which only covers the region of the impact point and is not extended along the central tube 14 all the way to the open end 26.

[0058] The impact point of the purging gas may be visualized, for example, in FIG. 2 in that a projection of a circumferential wall of the cone-shaped diffuser 120, which is arranged at the exit of the purging pipe 118 of the purging device 116, on the central tube 14 is carried out.

[0059] In comparison, the region 30 of the central tube 14 of the embodiment illustrated in FIG. 4 has a significantly shorter axial length 32 so that here the impact point of the purging gas would not be covered by the region and a damage of the filter medium 12 could possibly not be excluded therefore over the duration of operation.

REFERENCE CHARACTERS

[0060] 10 secondary element [0061] 12 filter medium [0062] 14 central tube [0063] 16 support element [0064] 18 radially outer side [0065] 20 inflow side [0066] 22 outflow side [0067] 24 radially outer side [0068] 26 open end [0069] 28 end disk [0070] 30 region [0071] 32 length [0072] 40 primary filter element [0073] 42 radially outer side [0074] 44 inner side [0075] 46 filter body [0076] 48 end disk [0077] 49 end disk [0078] 50 raw side [0079] 52 clean side [0080] 100 filter system [0081] 102 inlet [0082] 104 outlet [0083] 110 filter housing [0084] 112 housing top part [0085] 114 housing bottom part [0086] 116 purging device [0087] 118 purging pipe [0088] 120 diffuser [0089] 122 inflow guard [0090] 124 outflow socket [0091] L longitudinal axis