Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 022~9173 1998-12-21
WO 97/48470 PCT~P97/03076
Filter
The invention relates to a filter in accordance with the preamble of claim 1. Such filters are
known, for example from their use in the oil circuit of internal combustion engines. If it is
desired to use such filters, which are composed of a metal supporting fabric and a synthetic
sieve fabric with a metal inner tube and metal end plates, in modern internal combustion
engines, it is disadvantageous that the filter is composed of various different types of
materials. This presents problems, especially with regard to the later disposal of the filter.
Now the entire filter could be made of metal. This, however, is expensive to manufacture and
would therefore make the filter expensive. On the other hand it would increase the total
weight of the filter, which is disadvantageous with respect to the weight of the internal
combustion engine.
It is thus the task of the invention to improve a filter of the kind referred to above such that a
simple, cheap filter will result, which can be disposed of with little difficulty at the end of its
useful life.
According to the invention, this task is solved by a filter with at least one substantially
rectangular filter means and at least one substantially rectangular supporting medium which
is applied to the filter means as supporting means,, the composite media being pleated in a
star pattern and being joined sealingly at their contacting ends, the end faces of the filter
having a sealing cover. By using a substantially rectangular filter means the possibility is
created, for example, to unwind this filter medium from a continuous roll and insert it in
segments into an injection molding tool so that the supporting medium can likewise be
sprayed substantially at right angles onto the filter means. An advantage in this case is the
simple configuration of the injection molding tool. If the spraying of the supporting medium
were not to be performed until after the star-like pleating operation, a disproportionally more
costly injection molding tool would be needed.
A further embodiment of the invention envisions that the filter medium is composed of paper,
a nonwoven fleece, or a woven sieve fabric. Here, depending on the required fineness, the
selection of the appropriate filter means is especially easy.
.... .
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Furthermore, it is advantageously possible for the sieve fabric to be made of metal or
synthetic resin material. The material specified suitably will depend on the materials used for
the supporting medium and the covers, for the purpose of satisfying the requirements for a
pure type of material.
Another advantageous embodiment of the invention envisions making the covers of metal,
synthetic resin material or paper. The choice of the material of the covers will be made
~lo~Liate to the materials used for the screen and also for the supporting medium .
It can furthermore be provided that the supporting medium has film hinges, these film hinges
alternately permitting concave or convex folding relative to the star axis. As a result of this
alternating arrangement of hinges, the star-like folding of the initially flat filter produced in
an injection molding apparatus is made possible for the first time, since the folding takes
place the constrictions of the film hinges.
In another advantageous embodiment of the invention, the supporting medium in the area of
the film hinges, especially in the area of those film hinges which permit convex folding, has
angular indentations which define the angle of the star folding. Such mitering provides for a
regular appearance of the filter body, since such multi-layered structures otherwise tend to
fold irregularly, which would lead to undefined contours of the filter. Another advantage in
this case is that, for example the contacting ends can be definitely sealed.
In another advantageous embodiment, the ends which contact each other are glued or welded.
This results in secure sealing connections and consequently in a filter that is more secure in
use. Furthermore, one can provide for the covers to be welded, glued or snap-fastened to the
filter and supporting medium . Depending on the match of materials, these joints assure that
an inexpensive and reliable filter is produced.
Advantageously, it can be provided that at least one of the covers will contain a filter by-pass
valve. This assures that if a filter element clogs, the flow of oil within the internal
combustion engine will not be interrupted.
These and other features of preferred embodiments of the invention are found not only in the
claims but also in the description and the drawings, it being possible for the individual
CA 022~9173 1998-12-21
WO 97/~8470 PCT/EP97/03076
features to be realized individually or together in the form of sub-combinations in the
embodiment of the invention and in other fields, and may represent advantageous as well as
independently patentable embodiments for which protection is hereby claimed.
Embodiments of the invention are shown in the drawings and are explained in further detail
below.
The drawings show:
Figure 1 a section through a star-folded filter
Figure 2 the detail y of Figure 1
Figure 3 a side view of the supporting medium
Figure 4 the detail x of Figure 3
Figure 5 a plan view of the unfolded filter element
Figure 6 a section through a filter housing with two star filter inserts.
In Figure 1 a star-folded filter is illustrated in section. As shown enlarged in detail y, it can
be seen that the structure of the filter is made up essentially of the rectangular filter medium 2
and the supporting medium 3. As seen in Figure 2, in this special embodiment the filter
medium 2 is applied externally in relation to the star axis, although it could also be applied
inside of the supporting medium . The supporting medium 3 comprises, as shown in Figure
5, ribs disposed in the lengthwise and transverse directions, for example, which increase the
inherent stability of the filter. The supporting medium has indentations, especially in the
area of its film hinges 4, which permit convex folding relative to the star axis, which facilitate
a defined folding. In Figure 3 it can be seen that the film hinges 4 alternate such that, to
permit the star folding, one film hinge 4 permits convex folding 6 relative to the star axis, the
following film hinge permits a concave folding 7. In Figure 4 the detail x from Figure 3 is
shown enlarged. Here it becomes clear how the different film hinges 4 alternate. The angular
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indentations 8 in the supporting medium 3, which are necessary for the achievement of the
convex folding 6 are represented in this concrete embodiment with an angle of 60 degrees
with respect to the unfolded, flat outstretched supporting medium 3. The supporting medium
3 injected onto the flat outstretched, substantially rectangular filter medium 2, for example in
an injection molding process, is represented in Figure 5. Here a polyester fabric, for example,
which in this embodiment comes from a supply roll, is introduced into an injection molding
form. The filter medium 2 is severed from the roll either before or after the molding
operation. This injection molding operation produces the l~in~ted filter, which directly
after the molding operation is substantially rectangular and consequently flat. By means of
the film hinges 4 disposed in alternation along the length of the filter, it is possible to fold the
filter to a star shape, for example. As shown in Figure 1, the ends 9 of Figure 5 are glued or
welded after the folding operation. To finish the filter, so-called covers 5 are applied to its
end faces, which preferably are composed of the same material as the filter medium 2 and/or
the supporting medium 3.
In one embodiment, an apparatus for the filtration of oil, like the one represented in Figure 6,
is illustrated. This apparatus comprises a housing 10, a housing cover 11 which can be
mounted and dismounted by means of closing device 22 in order to change the filter, and by
means of a spring 16 urges the filter inserts l a and lb against the housing and seals the
housing 10 by means of a gasket 20. This apparatus furthermore comprises an inlet 13 and an
outlet 14. The embodiment illustrated in Figure 6 comprises two filters la and lb which also
have different finenesses. The first filter 1 a with the coarser filter medium, which
consequently lets larger particles pass, has in one of its covers 5 a filter bypass valve 12
which consists essentially of a valve plate 17 and a valve spring 18. The first filter is
separated from the second filter lb located in the housing 10, which has a finer filter medium,
by a cover 5 and an actuating valve 15 integrated therein. The actuating valve 15, which also
has a valve plate 17 and a valve spring 18, shuts off the first filter in the case, for example, of
a pressure in excess of 0.5 bar, for example, whereas the bypass valve in the first filter closes
only in critical states of operation in order to prevent running dry. The clean oil side is
separated from the raw oil side by the gasket 19 and the centering snap-fastening gasketed
connection. The limit of separation of the first filter ranges from about 40 ~,lm. In an
alternative embodiment it is possible to use only one filter insert in housing 10.
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W O 97/48470 PCT/EP97/03076
Reference Numerals
la first filter
lb second filter
2 filter medium
3 support material
4 film hinge
S cover
6 convex fold
7 concave fold
8 angular indentation
9 ends
1 0 housing
11 housing cover
12 filter bypass valve
1 3 inlet
14 outlet
15 actuating valve
1 6 spring
17 valve plate
18 valve spring
1 9 seal
20 cover seal
21 central snap tight connection
22 closure device
