U.S. patent application number 12/155173 was filed with the patent office on 2008-10-23 for method for the production of a filter element.
Invention is credited to Harald Mees, Michael Sakraschinsky.
Application Number | 20080257483 12/155173 |
Document ID | / |
Family ID | 30469339 |
Filed Date | 2008-10-23 |
United States Patent
Application |
20080257483 |
Kind Code |
A1 |
Mees; Harald ; et
al. |
October 23, 2008 |
Method for the production of a filter element
Abstract
A process for production of a filter element includes forming a
cylinder by bending a flexible filter mat having a series of folds
adjacent to one another at least in individual end areas on
longitudinal end edges thereof such that the end areas overlap with
end edges being aligned along a length of the cylinder, joining the
end areas on an exterior of the cylinder along a junction seam, and
reversing the cylinder inside out such that an annular filter
element is formed with the junction seam on an interior
thereof.
Inventors: |
Mees; Harald; (Lebach,
DE) ; Sakraschinsky; Michael; (St. Ingbert,
DE) |
Correspondence
Address: |
ROYLANCE, ABRAMS, BERDO & GOODMAN, L.L.P.
1300 19TH STREET, N.W., SUITE 600
WASHINGTON,
DC
20036
US
|
Family ID: |
30469339 |
Appl. No.: |
12/155173 |
Filed: |
May 30, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10522682 |
Jan 31, 2005 |
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PCT/EP2003/008271 |
Jul 26, 2003 |
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12155173 |
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Current U.S.
Class: |
156/210 |
Current CPC
Class: |
B01D 29/111 20130101;
B01D 29/232 20130101; Y10T 156/1025 20150115; B01D 2201/0415
20130101 |
Class at
Publication: |
156/210 |
International
Class: |
B31F 1/08 20060101
B31F001/08 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 2, 2002 |
DE |
102 35 275.5 |
Claims
1. A process for production of a filter element, comprising the
steps of: forming a cylinder by bending a flexible filter mat
having a series of folds adjacent to one another at least in
individual end areas on longitudinal end edges thereof such that
the end areas overlap with end edges being aligned along a length
of the cylinder; joining the end areas on an exterior of the
cylinder along a junction seam; and reversing the cylinder inside
out such that an annular filter element is formed with the junction
seam on an interior thereof.
2. A process according to claim 1 wherein after reversal of the
cylinder, the annular filter element is placed within a fluid
permeable support tube with tops of folds immediately adjacent the
junction seam engaging an inner surface of the support tube.
3. A process according to claim 1 wherein inner surfaces of the
cylinder are in contact as the end areas are joined by fusion to
form a fusion seam.
4. A process according to claim 1 wherein the end areas extend
directly from folds located on an exterior of the annular filter
element after reversal of the cylinder.
5. A process according to claim 1 wherein the flexible mat
comprises metal-free, plastic-supported filter mats.
6. A process according to claim 1 wherein dimensions are determined
for the flexible filter mat allowing reversing of the cylinder
after formation of an exterior fusion seam joining the end
areas.
7. A process according to claim 1 wherein a retaining device with
retaining elements is placed on the annular filter element to
overlap folds adjacent to the junction seam on surfaces of those
folds remote from the junction seam.
8. A process according to claim 7 wherein after reversal of the
cylinder, the annular filter element is placed within a fluid
permeable support tube with tops of folds immediately adjacent the
junction seam engaging an inner surface of the support tube; and
the retaining elements project radially inwardly from the inner
surface of the support tube.
9. A process according to claim 8 wherein the support tube is a
transfer-molded plastic with the retaining elements integrated
therein.
10. A process according to claim 7 wherein the retaining elements
are legs of a U-shaped clamping element that is inserted onto the
surfaces of those folds.
Description
REFERENCE TO RELATED APPLICATION
[0001] This application is a division and claims for priority of
U.S. patent application No. 10/522,682, filed Jan. 31, 2005 and
entitled Filter Element and the Method for Production Thereof, the
subject matter of which is hereby incorporated by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to a filter element having a
filter cylinder adjoining on its exterior a fluid-permeable support
tube through which filter cylinder fluid to be filtered may flow.
The filter element is made up of a filter mat web having a sequence
of folds adjacent to each other at least in individual areas. The
two ends of the filter mat web are joined to each other at a
connecting point to form an annular element. The present invention
also relates to a method for the production of such a filter
element.
BACKGROUND OF THE INVENTION
[0003] Such filter elements are available on the market, and are
widely used, for example, in hydraulic assemblies in branches of a
system through which hydraulic fluids flow. The known filter
elements are not entirely satisfactory with respect to their safety
in operation and the beta value stability of decisive importance
for filter output. With high fluid outputs in particular, the
danger exists that deformation or damage may occur at the junction
point at which the ends of the filter mat web are joined to form
the annular element forming the filter cylinder as a result of the
differential pressure of the fluid acting on the junction point.
Such damage and/or deformation of the folds in the area of the
junction point are identified by the common expression "fold
bulging".
SUMMARY OF THE INVENTION
[0004] An object of the present invention is to provide a filter
element with improved operating safety and beta value stability,
even with high flow output.
[0005] In a filter element, this object is basically attained by a
method of producing a junction point to prevent bulging of the
folds in the area of the junction point caused by the action of
fluid flow. According to the present invention, special protective
measures are taken at the point of junction of the filter mat web,
which prevent bulging of the folds in this area. The desired
improvement in operating safety is achieved even in the event of
high flow output and correspondingly high fluid differential
pressures in the area of the junction point.
[0006] In one preferred exemplary embodiment, the configuration
preventing bulging in the area of the junction point is formed by
the folds of the filter mat web being joined to each other along
their end edges. Such end edges face the interior of the annular
element to be formed, so that both folds adjacent to each other at
the junction point have their tops positioned on the exterior on
the annular element and facing the support tube. In that the
junction point, that is, the fusion seam or area of adhesion by
which the annular element forming the filter cylinder is closed, is
positioned in the interior on the filter cylinder, the junction
point on both sides rests on the support tube by the adjacent
folds. The tops of the folds are positioned on the exterior on the
annular element. In this configuration, the junction point forms no
point weak in resisting the active forces resulting from the
differential pressure applied in operation.
[0007] By preference, the filter mat web is in the form of a
flexible mat structure of metal-free plastic-supported filter mats
with connected ends of the filter mat web, so that a closed annular
structure is formed and is effected by a fusion seam. To make
simple and efficient production possible, the fusing process must
be carried out on the exterior of the annular element, that is,
with the junction point positioned on the exterior of the filter
cylinder. With such positioning, the fusion seam would form a weak
point of the filter cylinder during operation.
[0008] To make allowance for this factor, provision is made by the
present invention for an especially advantageous exemplary
embodiment such that the dimensions determined for the flexible
filter mat web are such that the annular element may be reversed
after formation of an exterior fusion seam. The fusion seam is then
positioned on the interior on the reversed annular element now
ready for use.
[0009] Despite the simplicity of the production method, that is,
formation of a fusion seam on the exterior, the annular element
forming the filter cylinder after reversal is protected as desired
from bulges in the area of the fusion seam now positioned in the
interior.
[0010] In place of the protection from bulges resulting from the
positioning of the junction point in the interior, or in addition
to this protection, according to the present invention the
configuration preventing bulging may have in the area of the
junction point a retaining device with retaining elements. The
retaining elements can overlap the folds of the annular element
adjoining the junction point on both sides, on the side of the
folds facing away from the junction point. Especially secure
support of the folds in the area of the junction point is thereby
ensured.
[0011] The retaining elements of the retaining device may be in the
form of a retaining projections formed on the inside of the support
tube and projecting radially inward.
[0012] As an alternative, the retaining elements may be in the form
of legs of a clamping element U-shaped in cross-section. The
clamping element may be inserted onto the folds adjacent to the
junction point of the annular element.
[0013] Other objects, advantages and salient features of the
present invention will become apparent from the following detailed
description, which, taken in conjunction with the annexed drawings,
discloses preferred embodiments of the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Referring to the drawings which form a part of this
disclosure:
[0015] FIG. 1 is a top plan view of an annular element forming a
filter element according to a first embodiment of the present
invention, in the partly completed state, with a fusion seam formed
on the annular element from the exterior and positioned on the
exterior;
[0016] FIG. 2 is a top plan view of the annular element of FIG. 1
in a finished state, that is, with the fusion seam positioned on
the interior after reversal;
[0017] FIG. 3 is a perspective view of the annular element of FIG.
2;
[0018] FIG. 4 is a perspective view of the filter disk formed in
the course of reversal of the annular element shown in FIG. 1;
[0019] FIG. 5 is a greatly enlarged, partial top plan view of a
fold section of the annular element of FIG. 2, along with data
indicating the dimensions;
[0020] FIG. 6 is a top plan view in section of a filter element
according to a second embodiment of the present invention;
[0021] FIG. 7 is a perspective view of the support tube of the
second embodiment shown in FIG. 6, without the filter cylinder
being present in this support tube; and
[0022] FIG. 8 is an exploded perspective exploded view of a filter
element according to a third embodiment of the present
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0023] FIGS. 1 to 5 illustrate a first exemplary embodiment of the
filter element of the present invention, the conventionally
configured support tube not being shown in these figures. The
filter cylinder 1 is in the finished state enclosed in this support
tube. In the form shown in FIGS. 2 and 3, it has been introduced
into the support tube (not shown). During operation, filter fluid
flows through the interior of the annular element indicated in
FIGS. 2 and 3; that is, the clean side of the filter device (not
shown) having the filter element according to the present invention
is situated on the exterior of the support tube enclosing the
annular element 1.
[0024] As shown in the figures, the annular element 1 is in the
form of a folded filter mat web joined at its two ends to form a
closed ring. The junction point is configured as a fusion seam 5.
In the exemplary embodiments described, the filter mat web is in
the form of a flexible mat structure possessing resilient
properties. More precise, the mat structure is of metal-free
plastic-supported filter mats fusible together by a fusion seam 5
extending longitudinally to produce the annular element 1.
[0025] By preference, a six-layer structure of the filter mat web
is provided which has the following layers in sequence: an exterior
support, a protective nonwoven layer, a prefilter layer, a main
filter layer, a nonwoven support layer, and an interior support. A
polyamide grid or a polyester fabric may be employed for the
exterior support. A polyester material may be provided as the
protective nonwoven layer. A glass fiber material, preferably in
reduced form with respect to thickness and base weight, or a
meltblown material may be employed for the filter layer. The main
filter layer may analogously be a glass fiber material, which
optionally is impregnated, or a meltblown material. A polyester or
polyamide material may in turn be used as the support nonwoven
layer, which may also be represented by a viscose nonwoven material
or a polyamide with meltblown material. The interior support may,
like the exterior support, be configured as a grid or fabric based
on a polyamide or polyester basis.
[0026] As shown in FIGS. 1 to 4, fusion seam 5 is displaced to the
interior in the finished state shown in FIGS. 2 and 3 by reversal
of the annular element 1 from the initial state illustrated in FIG.
1, in which the fusion seam 5 is positioned on the exterior, that
is to say, is in the form of a lengthwise seam made on the outside.
While in the state shown in FIG. 1, with fusion seam 5 positioned
on the exterior, on the outer edge of the annular element 1, a gap
7 exists in the area where there is no contact between the tops 11
of the folds 9 immediately adjacent to and on both sides the fusion
seam 5 and the enclosing support tube (not shown). In the state
shown in FIGS. 2 and 3 the tops 11 of the folds 9 immediately
adjacent to the fusion seam 5 are positioned on the outside (see
FIG. 2) and accordingly are positioned adjacent on the support
tube.
[0027] While in the state shown in FIG. 1 and at the differential
pressure prevailing during operation, the danger of bulging exists
in the area of the fusion seam 5. Fusion seam 5 may be moved
radially outward by pressure forces, with tensile forces active on
the fusion seam 5 tending to tear the seam open. In the reverse
state illustrated in FIGS. 2 and 3, no bulging result of radial
movement of the fusion seam 5 is possible, since the adjacent fold
top 11 is supported. The fusion seam 5 is also not subject to load
application in the form of forces of pressure tending to effect
separation.
[0028] FIGS. 4 and 5 illustrate the configuration and determination
of the dimensions of the filter mat web forming the annular element
1, that is, a configuration permitting reversal of the annular
element. The maximum length of the annular element permitting
reversal, if it is in the form of a flexible fold structure,
depends on the number of folds, the height of the folds, the
strength of the mat structure, and the thickness of the folds of
the annular element. FIG. 4 illustrates the exterior and interior
diameters of the disk element 13 which are temporarily obtained in
the course of reversal of the annular element 1. FIG. 5 illustrates
determination of the dimensions of the folds 9 with respect both to
strength of the material and to the fold size.
[0029] The maximum length of the annular element may be determined
as follows on the basis of the parameters entered in FIGS. 4 and 5,
wherein [0030] F.sub.ANZ=number of folds [0031] F.sub.H=height of
fold [0032] F.sub.D=thickness of fold [0033] M=strength of material
of mat structure [0034] L.sub.M=extended length of filter web
[0035] L.sub.Mmax=maximum extended length of filter web [0036]
D.sub.amax=maximum external diameter of filter disk [0037]
D.sub.i=internal diameter of filter disk [0038] L.sub.max=maximum
length of filter cylinder
[0038] L M = 2 * F Anz * ( F H - 2 * M + .pi. * M 2 ) 1 ) D a max =
D i + 2 * L max 2 ) L max = D a max - D i 2 3 ) D i 2 = F Anz * F D
.pi. 4 ) L M max = D a max * .pi. 5 ) D a max = L M max .pi. 6 ) D
a max = D i + 2 * L max 7 ) L max = D a max - D i 2 8 ) L max = L M
max .pi. - D i 2 8 ) with value of 6 ) 9 ) L max = L M max - F Anz
* F D 2 * .pi. 9 ) with value of 4 ) 10 ) L max = F Anz * ( F H - 2
* M + .pi. * M 2 - F D 2 ) .pi. 10 ) with value of 1 ) 11 )
##EQU00001##
[0039] FIGS. 6 and 7 illustrate a second exemplary embodiment of
the filter element according to the present invention. Unlike the
preceding example, the support tube 15 enclosing the filter
cylinder is shown. This support tube 15 is shown separately in FIG.
7, that is, without the filter cylinder inserted. As is clearly
shown in FIG. 7, the support tube 15, which is of transfer-molded
plastic, has on the exterior, which in a filter device of the
present invention adjoins the clean side, has strips 17 extending
longitudinally, strips 17 are connected by webs 19 forming annular
elements between which are apertures 21 defining fluid passages. As
shown in FIG. 6, when a filter cylinder has been inserted into the
support tube 15, the area adjacent to and on both sides of the
fusion seam 5 is secured by a retaining device. The retaining
device projections 23 and 25 overlap the folds of the annular
element adjacent to the fusion seam, on both sides of the fusion
seam and on the sides of those folds facing away from the fusion
seam 5 (see FIG. 6).
[0040] As shown in FIG. 7 in particular, the retaining projections
23 and 25 are integrally molded on the inside of the support tube
15. Retaining projection 23 is configured to extend along and
through a strip 17 of the support element. The divided retaining
projections 25 are provided on the other side between which are
interstices 27 corresponding to the apertures 21 forming the fluid
passages. With the enclosure of the area of the fusion seam 5
formed by the retaining projections 23 and 25, effective protection
is obtained from the danger of bulging in the area of the junction
point.
[0041] FIG. 8 shows a third exemplary embodiment of the present
invention having a support tube 15 without interior retaining
projections 23 and 25. In place of the enclosure of the area of the
junction point, that is, the fusion seam 5, this exemplary
embodiment provides a retaining device having a metal clamping
element 31. The clamping element is U-shaped in cross-section, and
may be positioned by insertion on the sides of the adjacent folds
facing away from the fusion seam 5. The retaining action
essentially corresponds to that of the retaining projections 23 and
25 of the second exemplary embodiment.
[0042] In addition, in the example shown in FIG. 8, the annular
element 1 has been reversed to assume the state shown in FIG. 2.
The fusion seam 5 is then positioned in the interior and the tops
of the folds adjoining this seam are supported directly by the
support tube 15. Consequently, this exemplary embodiment is
protected in two ways from bulging in the area of the fusion seam
5.
[0043] While various embodiments have been chosen to illustrate the
invention, it will be understood by those skilled in the art that
various changes and modifications can be made therein without
departing from the scope of the invention as defined in the
appended claims.
* * * * *