Patent Application
20120324850
The invention concerns an air filter element comprising a cylindrical tubular filter bellows that is closed off at its end faces by a terminal disk, respectively, that each comprise at least one annular seal or an annular seal section of a sealing member.
Terminal disks are required in order to be able to provide a sealing action of the filter element in an air filter housing and to force the predetermined radial flow path through the filter bellows. At least one terminal disk is provided on the exterior side that is facing away from the filter bellows with an annular sealing member. The sealing member is conventionally produced such that the terminal disk is inserted into a casting mold and then a liquid polymer material is filled in and flows into an annular penetration or recess at the terminal disk and/or the casting mold. After hardening or cross-linking the casting mold is removed so that in the area of the previously existing annular gap a sealing surface at the terminal disk is exposed.
The described manufacture is however complex and therefore cost-intensive. As a result of the hardening time or the time required for cross-linking of the polymer material, it is necessary in mass production of the filter element to provide a large number of casting molds. When on the terminal disk and/or on the sealing member geometric changes are to be realized, all casting molds must be retooled or even new ones manufactured. During the production process also significant expenditure is required in order to prevent a strong adhesion of the hardening polymer material on the casting mold. For this purpose, for each production process a release agent must be applied to the area of the casting mold that comes into contact with the liquid material. This area is also provided additionally with a non-stick coating. Residual adhered material on the casting mold requires always a thorough cleaning after several processing cycle.
On the finished filter element the annular sealing member with its outer surface is exposed so that for avoiding contamination and/or damage it must be covered during transport to the assembly site.
Finally, the end user is faced with the problem that in general he cannot recognize whether he is dealing with a new original part of the manufacturer or with a reprocessed replacement part.
A first object of the invention thus resides in that the manufacture of the filter element of the aforementioned kind should be realized more economically. A further object resides in that a protection of the exposed sealing member is to be effected and a seal function is to be integrated.
These objects are solved for an air filter element having the features of the preamble of claim 1 in that the annular seal is covered by a manually removable cover ring and/or in that a central cutout in the terminal disk is covered by a manually removable cover disk.
Preferably, the cover ring is connected directly by two concentric weakened sections to the terminal disk. A rip tab that is integrally formed or connected in other ways makes it possible to partially remove the cover ring and then peel it off along the weakened section so that the sealing member located underneath is exposed and the air filter element can be mounted in the designated housing.
It is also possible to provide a film ring that covers the annular gap in the terminal disk and is glued to the neighboring edge areas of the annular gap. Here, by tearing off the cover ring, the sealing member can be exposed also. The film ring can be comprised of aluminum foil, plastic film or composite materials.
The cover ring can moreover be formed by an auxiliary part pressed into the annular gap of the terminal disk that is in particular formed of synthetic material that has bad adhesion properties, for example, formed of polyethylene, polypropylene, or another polyolefin. Other embodiments may comprise clip-on cover rings.
The annular seal can also be formed on an inner edge of an annular terminal disk. In this case, instead of a cover ring a cover disk is provided that covers the entire central expansion. Otherwise, the same functions and variants are possible as in case of the annular cover.
By means of all embodiments the desired protection for the sealing member is effected and a seal function is provided. At the same time, with the terminal disk configured in accordance with the invention on a filter element, its manufacture is significantly simplified.
A method according to the invention for manufacturing an afore described air filter element provides that casting molds are completely obsolete. Thus, all costs for the manufacture and maintenance of casting molds are eliminated. The elastomer material is filled directly into the covered recesses of the terminal disk wherein the annular gap that is open in operation of the filter element is still closed off by the cover rings provided in accordance with the present invention. The liquid polymer sealing material flows thus only to the cover ring but cannot escape from the casting mold that is formed by the terminal disk itself. The backside of the cover ring effects at the same time a structuring of the sealing member, for example, with additional grooves, and thus functions as a matrix.
An alternative method for producing a filter element provides that instead of a liquid polymer sealing material the terminal disk is to be produced by a two-component injection molding process. In this connection, the sealing member is formed of a thermoplastic elastomer. In this case, there are again tooling costs for the production but the desired protection of the sealing member and the seal function by means of an integrally injection-molded cover ring can also be effected with this manufacturing process.
The weakened sections for later easier removal of the cover ring can also be formed by the injection molding process.
When the seal function provided according to the invention is not required but only the production without casting molds is desired, the cover rings can also be removed automatically during the manufacture of the filter element. The possibility of manual removal facilitates also automated removal: for example, the rip tab can be simply gripped by a stationary gripping device. Subsequently, the filter element is rotated above its center axis so that the cover ring is torn off.
The cover ring can also be expanded by an inwardly positioned circular cover surface so that a completely closed cover disk is provided that at least at its outer edge is connected to the edge area of the sealing ring gap and that upon utilization of the filter element can be completely removed. By covering the central area, the area of the central tube on the filter element is closed off also so that it is additionally protected from dirt penetrating into it. The additional central cover has the additional advantage that with simple measures at the installation site in the air filter housing, for example, by means of a centering projection onto which the filter element is to be pushed, a utilization of the filter element is not possible as long as the cover disk has not yet been removed.
The invention will be explained in the following with the aid of the drawings in more detail.
The terminal disk 20′ is completely covered by cover disk 30′ wherein
In particular, the central inner flow channel I of the filter element 10 is covered so that insertion of the filter element 10 into an air filter housing is not possible until the cover disk 30′ has been removed. For this purpose, the cover disk 30′ is provided with a rip tab 31′ by means of which it can be easily gripped.
The outer annular area 25′ ends at a web 25.1. In the direction toward the central inner cutout I the terminal disk 20′ has an additional annular section 23′ that is partially covered on the inner wall surface by the annular sealing section 22.3′ which is part of the sealing member 22′. The cover disk 30′ is connected to the terminal disk 20′ at the tip of the web 25.1′. The wall thickness of this connecting location is very thin in order to facilitate a simple tearing off by hand.
A structured surface area 32′ of the cover disk 30′ serves for forming a structured surface on the annular sealing section 22.2′ of the sealing member.
The manufacture of an air filter element 10 according to the invention will be explained in the following with reference to the
a shows a terminal disk 20 in accordance with the embodiment illustrated in
Subsequently, a suitable material for forming an elastomer sealing member is introduced in liquid or pasty form into the thus formed casting mold wherein the annular gap 24 between the webs 23.1,25.1 is filled and also the outer annular area 25 is covered.
The filter bellows 11 (compare
Finally, for the opposite end of the filter bellows 11 a further terminal disk 20′ is oriented such that the surface that faces outwardly again later on during use is facing downwardly and the inner surface is open in the upward direction so that an elastomer material can be filled in and the still free end of the filter bellows 11 can be placed therein. A matrix stamp 200 (compare
| Number | Date | Country | Kind |
|---|---|---|---|
| 20-2006-011-989.2 | Aug 2006 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP07/57749 | 7/27/2007 | WO | 00 | 11/2/2009 |
