Filter Body

Abstract

A filter body has a longitudinal axis and a first end face and a second end face opposite the first end face in a direction of the longitudinal axis. The filter body has a zigzag-folded filter medium arranged about the longitudinal axis, wherein the filter body has an inner circumference and an outer circumference and fold edges of the filter medium are positioned on the inner circumference and/or the outer circumference. The filter body further has a securing coil of at least one circumferentially extending thread applied onto the outer circumference. The fold edges have, at least over sections thereof, several embossments arranged such that the fold edges that are next to each other are secured relative to each other by the embossments.

Description

BACKGROUND OF THE INVENTION

The invention concerns a filter body, in particular for use as an air filter of an internal combustion engine, as well as a filter element with a filter body and a filter system for installation of such a filter element.

WO 2009/047196 A1 discloses a filter element for internal combustion engines that is comprised of a zigzag-folded filter medium in a concentric shape, a first open or closed end disk arranged on an end face and a second end disk arranged on the oppositely positioned end face wherein the end disk has a concentric opening and extends substantially as a circular ring across the folds of the filter medium. The filter element has annular beads and sealing grooves for sealing the filter element in a housing.

Moreover, WO 2009/047196 A1 discloses a filter system with a filter element. This filter system serves in particular for filtration of the intake air of an internal combustion engine and is comprised of a housing and a removable cover for receiving the filter element. The filter system has two annular grooves that communicate with the sealing contours of the filter element in the area of the sealing action.

In principle, the reliable sealing action of a filter element in a housing is important for reliable operation. The sealing action should be temperature-resistant and vibration-resistant. The sealing action of the filter element must be ensured also in connection with devices or facilities that are exposed to strong vibrations or impacts. At the same time, the filter element should, if possible, contain no metallic parts so that it can be thermally disposed of without problems. In order to ensure these properties, a high mechanical stability of the filter element, whose filter medium usually consists of paper or nonwoven, is required for the duration of the entire service life.

It is therefore an object of the invention to design a filter body for a filter element such that a high mechanical stability of the filter element for the duration of its service life is ensured, even under unfavorable environmental conditions such as moisture and/or great temperature fluctuations.

A further object of the invention is to provide a filter system with such an exchangeable filter element that exhibits a high mechanical stability for the duration of its service life, even under unfavorable environmental conditions such as moisture and/or great temperature fluctuations.

SUMMARY OF THE INVENTION

In accordance with the present invention, this is achieved according to one aspect of the invention with a filter body that has fold edges arranged on the inner and/or outer circumference of the filter body, wherein the fold edges, at least over sections thereof, have several embossments that secure neighboring fold edges relative to each other and wherein a securing coil of at least one circumferentially extending strip or thread is provided on the outer circumference of the filter body.

According to another aspect of the invention, a filter system with such a filter body is provided.

Accordingly, a filter body having a longitudinal axis and two end faces is proposed that comprises a filter medium that is arranged about a longitudinal axis a zigzag-folded shape and has an inner circumference and an outer circumference. The fold edges of the zigzag shape are arranged on the inner and/or outer circumference of the filter body and the fold edges, at least over sections thereof, have several embossments which secure neighboring fold edges relative to each other and wherein a securing coil of at least one circumferentially extending strip or thread is applied to the outer circumference of the filter body

The embossments can be applied, for example, by rolling of the folded filter medium wherein the fold edges of the folded filter medium are depressed at sequentially arranged fold edges in a defined way. The fold edge widens at the rolled location and can thus be supported on the embossment of the neighboring fold edge. In this way, the filter body can be advantageously stabilized relative to deformation. The embossments can be arranged as a circumferential structure on the circumferential surface of the filter medium at the same axial height. Conceivable is also to design the embossments so as to alternate on the circumferential surface with areas that are not embossed, instead of providing circumferentially arranged embossments. In this case, it is advantageous when embossed and non-embossed areas at the circumference are staggered relative to each other for axially neighboring embossments.

By supporting the fold edges by means of a combination of embossments on the outer circumference and/or on the inner circumference of the filter body, i.e., at the incoming flow side and/or at the outgoing flow side of the filter body, and of securing coils, the folds are uniformly distributed in the circumferential direction. By combination of the embossments at the incoming flow area and/or outgoing flow area of the filter body and the fixation by the securing coil, an advantageously arranged fold position and fold distribution results. This combination of measures provides straightness of the folds in their length-wise extension in the direction of the longitudinal axis of the filter body which is very beneficial relative to variants employing a support action solely by embossments or solely by spiral securing coils. Effects like compaction, slanted or tilted positioning, or wave formation of the folds of the filter medium by environmental influences, such as water, moisture in the air, temperature and the like are significantly reduced with this arrangement. The embossments ensure a uniform spacing of the folds and thus provide an optimal passage for the incoming medium. Moreover, a defined dust pocket remains that counteracts compaction of the folds. The securing coil secures the fold spacing that is adjusted by the embossments and ties the filter medium to a compact filter body. The stiffness of the filter body remains intact in this way. In addition, the filter body absorbs, without fold deformation, the axial clamping forces occurring upon installation of a filter element constructed from the filter body in a housing.

In a beneficial embodiment, the filter medium can be made of paper, paper reinforced with plastic fibers, and/or plastic-coated paper. The use of these materials as a filter medium represents a very economic possibility for realizing such a filter element. At the same time, the described shaping provides a stable arrangement so that a self-supporting configuration of the filter body and thus beneficial mounting properties are provided.

Advantageously, the securing coil may comprise at least one strip or thread extending in the direction of the longitudinal axis on the outer circumference of the filter body. With additional strips or threads perpendicular to the circumferentially extending threads or strips on the outer circumference of the filter body, the securing coil can be additionally reinforced and is thus suitable for very rough environments. Also, very large and heavy filter bodies, for example, for use in construction machines or agricultural machinery can be additionally stabilized in this way.

In one embodiment, one or several strips or threads are wound in a coil shape about the outer circumference to form the securing coil. In this connection, it can be advantageous to provide areas with different pitch. For example, in the area adjacent to the closed end disk, the thread can be wound with reduced pitch so that the threads or strips are closer to each other, for example, spaced by less than 2 cm (0.8 inches), preferably approximately 1 cm (0.4 inches). In this way, in this area a grip or handling-resistant zone can be provided in which the filter medium is reinforced for absorbing the manually applied operating forces when exchanging the filter element.

Expediently, the securing coil can be comprised of plastic-impregnated thread or strip. Such threads or strips have the advantage that they are moisture-resistant, have an excellent long term behavior, and also exhibit additional strength so that the filter body as a whole is more stable.

In an advantageous embodiment, the securing coil can be glued onto the filter medium. The strip or thread of the securing coil can be wound from a bath of hot-melt adhesive onto the filter body. When the filter body with securing coil is subsequently subjected to a heat treatment, the hot-melt adhesive can fuse with the filter medium and cure and, in this way, imparts to the securing coil and the filter body a significant strength. Alternatively, other curing methods, depending on the employed glue, can be used. For example, curing methods employing UV light can be used also.

Advantageously, the filter body can have at least at one end face a reinforcement ring. In this way, the filter body is provided with a further stabilizing element that, together with the combination of embossments and securing coil, serves for improved absorption of the axial clamping forces upon installing a filter element made therefrom in a housing.

The invention concerns according to a further aspect a filter element that comprises a filter body, a first open or closed end disk that is arranged at an end face and a second end disk that is arranged at the second oppositely positioned end face as well as a support tube concentrically arranged relative to the longitudinal axis and extending between the first and second end disks. Such a filter element is ready to be mounted and can be used in a filter system, for example, of an internal combustion engine. In this context, the two end disks and the support tube serve for mounting and sealing in the housing of the filter system.

Advantageously, the second end disk, like the first end disk, can be comprised of polyurethane foam or an elastomer. Of course, there is also the possibility to produce the end disk from several plastic components in order to ensure an optimal deformability across a wide temperature range, which may be encountered when using the filter element in practice. Accordingly, thermoplastic synthetic materials are not excluded. Both end disks can be fused (welded) or glued to the filter body in order to provide a stable connection.

Expediently, the first end disk can have a radial seal relative to the housing. This has the advantage that in addition to an excellent sealing action and thus a safe filtering action, due to the radial seal a radial guiding of the filter element in the housing can be effected and, in this way, a very stable securing action of the filter element in the housing is provided.

Expediently, the filter element can be used as an air filter, in particular as an air filter of an internal combustion engine. The safe operation of internal combustion engines is based also on a safe and favorable filtering of the intake air for combustion. The disclosed filter element provides an economic possibility for this purpose.

Advantageous is also the use of the filter element as a particulate filter, in particular as a diesel particulate filter of an internal combustion engine. Here also safe mounting and economic exchangeability of the described filter element are of decisive importance.

The invention concerns, according to a further aspect, a filter system with a filter element, comprising a housing which is substantially concentrically configured about a longitudinal axis; a cover that closes off the housing and that is also concentrically designed relative to longitudinal axis; an inlet arranged on the housing and/or the cover for supply of the medium to be filtered, in particular air; wherein on the housing, concentric to the longitudinal axis, an outlet for discharging the filtered medium is provided; wherein on the housing in the area of the outlet a sealing contour is provided which corresponds with the radial seal of the first end disk of the filter element; wherein the filter element is exchangeably arranged in the housing of the filter system. The important advantage of such a filter system resides in the very safe and stable installation of the filter element as well as in the economic exchangeability or replacement of the filter element in a service situation. Especially for a short service life, as in use in the field of agricultural or construction machinery, the fast exchangeability is of great importance.

Advantageously, in the area of the inlet of the filter system, a cyclone separator can be provided and a dirt outlet can be provided on the housing or on the cover. This cyclone separator is comprised of a guiding geometry that causes the medium to be filtered to rotate. Due to this rotation, the dirt is concentrated in the area of the housing wall and is discharged at a suitable location by means of the dirt outlet. By preseparation of most of the dirt from the air to be filtered, the service life of the actual filter element can be decisively prolonged.

According to a further embodiment of the invention, a secondary element can be arranged in the interior of the filter element. The secondary element that may be comprised of a support structure that is covered with a permeable filter medium, for example, a nonwoven, has the task of keeping closed the outlet of the filter system during exchange of the filter element so that no dirt can penetrate into this area while the filter element is cleaned or replaced. The secondary element in a preferred embodiment is connected by a screw connection with the housing and is provided with a seal relative to the housing.

BRIEF DESCRIPTION OF THE DRAWING

Further advantages result from the following description. In the drawing, exemplary embodiments of the invention are illustrated without being limiting. The drawings, the description, and the claims contain several features in combination. A person of skill in the art will consider the features expediently also individually and will combine them to other meaningful combinations.

FIG. 1 shows in a perspective view a filter system according to an embodiment of the invention with tangential inlet, central outlet, and dirt outlet at the bottom side.

FIG. 2 shows in a perspective view a filter system according to an embodiment of the invention with radial inlet and central outlet.

FIG. 3 is a longitudinal section of the filter system according to an embodiment of the invention with tangential inlet, central outlet, and dirt outlet at the bottom side.

FIG. 4 is a schematic illustration of a filter body according to the prior art with embossments on the inner and outer circumference of the filter body.

FIG. 5 is a schematic illustration of a filter body according to an embodiment of the invention with embossments on the inner and outer circumference of the filter body as well as a securing coil on the outer circumference.

FIG. 6 is a schematic illustration of a filter body according to a further embodiment of the invention with embossments on the inner and outer circumference of the filter body, a securing coil on the outer circumference, and a reinforcement ring at an end face.

FIG. 7 is a filter element made of a filter body according to FIG. 5

FIG. 8 is a longitudinal section of the filter element according to FIG. 7.

FIG. 9 is an enlarged view of a part of the longitudinal section through the filter element according to FIG. 7.

In the Figures, same components or components acting in the same way are identified with the same reference characters. The Figures show only exemplary embodiments and are not to be understood as limiting.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows in a perspective view a filter system 100 according to an embodiment of the invention with tangential inlet 102, central outlet 104 at an end face of the housing, and a dirt outlet 106 at the bottom side. Illustrated is a round filter configuration that is comprised of a housing 108 that is closed off by a cover 110, for example, by a screw connection or bayonet coupling connection. When used as an air filter system, dust-laden air flows into the inlet 102 that is arranged tangential to the air filter element arranged in the interior of the housing so that the air in the interior of the housing 108 is caused to rotate by an incoming flow protector at the filter element. Filter element and incoming flow protector are not illustrated in the drawing. Due to the cyclone effect caused by the rotational movement of the air, centrifugal forces are acting on the dust particles contained in the incoming air so that the dust particles are partially separated at the housing wall and can be discharged by means of dirt outlet 106 from the filter system 100. In this way, the filter element is loaded less and the service life of the filter element is increased. The purified air can be discharged via the central outlet 104 from the housing 108.

FIG. 2 shows a perspective view of a filter system 100 according to an embodiment with inlet 102 at the cover and central outlet 104. Illustrated is also a round filter configuration comprised of a housing 108 that is closed off by a cover 110. The inlet through which the dust-laden air can enter the housing is in this case arranged centrally above the filter element installed in the interior. The outlet 104 through which the purified air can flow out is centrally arranged, as also shown in FIG. 1.

Such filter systems as illustrated in FIGS. 1 and 2 are usually employed in construction machinery and agricultural machinery. They are characterized by great robustness and have a short service life due to their high dust load. A filter system 100 with loaded filter element must be able to tolerate a weight increase of 10 kg or more.

In FIG. 3 a longitudinal section of the filter system 100 according to an embodiment of the invention with tangential inlet 102, central outlet 104, and dirt outlet 106 at the bottom side is illustrated. The housing 108 of the filter system 100 is closed off by a cover 110. The filter element 10 that is comprised of a support tube 14 concentrically arranged about longitudinal axis L and the filter body 12 is provided at two opposite end faces 15, 17 with first and second end discs 16, 18 that are, for example, made of castable polyurethane, in particular polyurethane foam, or an elastomer. The second end disk 18 and the support tube 14 of the filter element 10 may be configured together as a monolithic component. The filter body 12 can be folded, for example, in a zigzag shape, can be of an annularly closed configuration, and can be comprised of paper, paper reinforced with plastic fibers, and/or of plastic-coated paper.

The second end disk 18 whose stability is increased by a reinforcement plate 30 has support knobs 20 which, upon installation into the housing 108 provided for receiving the filter element, are supported axially as well as radially on the housing 108 by contacting an inner cover contour 114 of the cover 110. On the oppositely positioned end face 15 of the filter element 10, a radial seal 26 is provided on the first end face 16 whose stability is increased by the reinforcement ring 31. With the radial seal 26, the filter element 10 is radially supported via sealing contour 116 on the housing 108 and seals the unfiltered air chamber relative to the filtered air chamber. The filter element 10 is thus axially as well as twice radially clamped relative to the housing 108.

Dust-laden air can be flowing in through the inlet 102 in the direction of arrow 40; the inlet 102 is in this case illustrated as a tangential inlet and enables, due to the rotational movement of the air which is effected by the cyclone separator 36, a cyclone operation. Dust particles, partially pre-separated by the rotational movement, can deposit on the inner housing wall and by means of the dirt outlet 106, in case of installation of the filter housing 108 in horizontal position, can be discharged in downward direction by the force of gravity from the filter system 100. In operation, the air flows, after partial separation of the dust particles, through the filter body 12 in the direction of arrows 42, 44 into the interior 50 of the filter element. Dust particles are retained within the filter medium, beginning at a certain size of the particles that depends on the filter medium. Depending on the dust load, the filter element 10 must be exchanged after a certain operating time.

Via the outlet 104, the filtered air flows in the direction of arrow 46 out of the system. In the interior 50 of the filter element 10, i.e., in the clean air area, a secondary element 28 is provided that is substantially comprised of a support structure with a filter medium that has a relatively high permeability, for example, a nonwoven, and upon exchange of the filter element 10 remains in the housing 108 for protecting the downstream air guiding passage, for example, of an internal combustion engine, against penetration of dust particles and other objects. The secondary element 28 is fixedly screwed on by a screw-on part 32 onto the outlet-side component of the housing 108 and is sealed by a radial seal.

FIG. 4 shows a purely schematic illustration of a filter body 12 with end faces 52, 54 according to the prior art with embossments 64 on the inner and outer circumference 58, 60 of the filter body 12. The filter body 1, illustrated purely schematically in the shape of a hollow cylinder of the filter medium 56 without providing details of the zigzag-folded filter medium, has embossments 64 which are arranged in an annular shape on the inner as well as outer circumference 58, 60 of the filter body 12. In principle, these embossments 64 in the filter medium 56 can be produced prior to producing the filter body 12 in the semi-finished product, i.e., in the folded paper. Conceivable is however also an embossment process by means of suitable embossment stamps after the filter body 12 has been converted into its final shape.

In a concrete embodiment, the filter body 12, with its longitudinal axis L and two end faces 52, 54, comprises a filter medium 56 that is arranged about longitudinal axis L and is folded in a zigzag shape and provided with an inner circumference and an outer circumference 58, 60. Fold edges 62 are positioned on the inner and/or outer circumference 58, 60 of the filter body 12 and the fold edges 62 at least partially have several embossments 64 which secured neighboring fold edges 62 relative to each other.

It is beneficial when the filter medium 56 is made of paper, paper reinforced with plastic fibers, and/or plastic-coated paper.

FIG. 5 shows also in a purely schematic illustration a filter body 12 with the end faces 52, 54 according to an embodiment of the invention with embossments 64 on the inner and outer circumference 58, 60 of the filter body 12 as well as a securing coil 66 on the outer circumference 60. In addition to the annular embossments 64, annular threads of a securing coil 66 are provided. The securing coil is provided on the outer circumference 60 of the filter body 12 for reinforcement of the entire composite. The inner circumference 58 of the filter body 12 is simply embossed with embossments 64.

In the concrete embodiment of the invention, the filter body 12 is provided in addition to the embossments 64 with a securing coil 66 of at least one circumferentially extending thread or strip 68 on the outer circumference 60 of the filter body 12. Further, the securing coil 66 can have at least one thread 68 perpendicular to the circumferentially extending threads in the direction of the longitudinal axis L on the outer circumference 60 of the filter body 12 in order to thereby additionally stiffen or reinforce the filter body 12. The securing coil 66 can be expediently comprised of a plastic-impregnated thread or strip in order to protect the thread/strip from the effects of moisture. The securing coil 66 can moreover be secured on the filter medium 56 by a hot-melt adhesive connection after application on the outer circumference 60 of the filter body 12.

In FIG. 6, a filter body 12 according to a further embodiment of the invention is illustrated purely schematically. The filter body 12 is provided with embossments 64 on the inner and outer circumference 58, 60 of the filter body 12, a securing coil 66 on the outer circumference 60, as well as a reinforcement ring 70 on an end face 54. In one area of the filter body 12, an improper handling protector 72 (protector to prevent damage by improper handling) in the form of, for example, a film is illustrated by means of which the filter body 12 as a finished filter element can be installed in and removed from a housing by hand.

FIG. 7 shows a filter element 10 comprised of a filter body 12 according to FIG. 5. The filter body 12 is in this context provided with a first open or closed end disk 16 arranged at an end face 15 and a second end disk 18 at the opposite end face 17 that effect an additional reinforcement of the filter element 10 and also, as elastic elements (they are comprised usually of polyurethane form or an elastomer), enable installation and clamping of the filter element 10 in a housing. Moreover, it has a support tube 14 that is concentric to the longitudinal axis L and extends between the first and second end disks 16, 18. The first end disk 16 has a radial seal 26 for sealing relative to a housing.

In FIG. 8 a longitudinal section of a filter element 10 according to FIG. 7 is illustrated. The section through the filter body 12 that is positioned between the two end discs 16, 18 that may be comprised e.g. of injection-molded polyurethane or elastomer has embossments 64 at regular spacings relative to each other. The embossments 64 are embodied as recesses in the filter medium 56. Also provided are strips or threads of a securing coil 66 applied on the filter medium 56. In this way, a significant reinforcement of the filter body 12 even in case of introduction of some moisture and in case of great temperature fluctuations of the filtered air is provided.

FIG. 9 shows an enlarged view of a part of the longitudinal section of the filter element 10 according to FIG. 7. In this illustration, the recesses of the embossments 64 as well as the applied threads of the securing coil 66 can be seen more clearly.

While specific embodiments of the invention have been shown and described in detail to illustrate the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles.

Claims

1. A filter body having a longitudinal axis and a first end face and a second end face opposite the first end face in a direction of the longitudinal axis, wherein the filter body is comprised of a zigzag-folded filter medium arranged about the longitudinal axis, wherein the filter body has an inner circumference and an outer circumference and fold edges of the filter medium are positioned on the inner circumference and/or the outer circumference, and is further comprised of a securing coil of at least one circumferentially extending thread applied onto the outer circumference, wherein the fold edges have, at least over sections thereof, several embossments arranged such that the fold edges that are next to each other are secured relative to each other by the embossments.

2. The filter body according to claim 1, wherein the filter medium is paper, paper reinforced with plastic fibers, and/or plastic-coated paper.

3. The filter body according to claim 1, wherein the securing coil comprises at least one thread extending in the direction of the longitudinal axis on the outer circumference.

4. The filter body according to claim 1, wherein the securing coil is comprised of a plastic-impregnated thread.

5. The filter body according to claim 1, wherein the securing coil is glued onto the filter medium.

6. The filter body according to claim 1, further comprising a reinforcement ring disposed on at least one of the first and second end faces.

7. A filter element comprising: a filter body according to claim 1;a first end disk arranged at the first end face of the filter body and a second end disk arranged at the second end face of the filter body;a support tube that is concentrically arranged relative to the longitudinal axis of the filter body and extends between the first and the second end disks.

8. The filter element according to claim 7, wherein the second end disk is comprised of a polyurethane foam or an elastomer.

9. The filter element according to claim 7, wherein the first end disk has a radial seal for sealing relative to a housing.

10. The filter element according to claim 7 as an air filter.

11. The filter element according to claim 7 as a filter element of an internal combustion engine.

12. The filter element according to claim 7 as a particulate filter.

13. The filter element according to claim 7 as a diesel particulate filter of an internal combustion engine.

14. A filter system comprising; a housing that is configured substantially concentrically about a longitudinal axis;a cover closing off the housing and concentrically configured relative the longitudinal axis;a filter element according to claim 7 disposed exchangeably in the housing;an inlet arranged at the housing and/or the cover wherein a medium to be filtered is supplied via the inlet;an outlet arranged concentrically on the housing relative to the longitudinal axis, wherein filtered medium is discharged via the outlet;wherein a sealing contour is provided on the housing in the area of the outlet, wherein the sealing contour corresponds with a radial seal of the first end disk of the filter element.

15. The filter system according to claim 14, further comprising a cyclone separator disposed in the area of the inlet and further comprising a dirt outlet disposed at the housing or at the cover.

16. The filter system according to claim 14, further comprising a secondary element arranged in an interior of the filter element.

17. The filter system according to claim 16, wherein the secondary element is connected to the housing and remains within the housing when the filter element is exchanged.