DE3602153A1 - Process for winding particle filters - Google Patents

Abstract

To wind particle filters, in particular exhaust gas filters, a process is proposed in which the fibre strands (11) composed of a plurality of elemental filaments (18) are wound loosely and in a plurality simultaneously at a distance from each other. The fibres of different winding layers (15) are laid at different angles. Such a wound body has a certain porosity which has a depth filter action. <IMAGE>

Description

The invention relates to a method for winding of particle filters for gases, especially exhaust gases which the fibers around a releasable winding aid, for. B. Thorn be wrapped.

Using different methods to manufacture particle filters a filter designed as a winding body is also known. These are made in relatively thin, on one Support body wound fiber layers used and each after application in several or fewer quantities used to get the required filter surface receive.

The gas mixed with particles, for example exhaust gas Internal combustion engines, flows through the operation Fiber filter body and the breakthrough Support body. The particles contained in the gas become held onto the surface of the filter. Such filters are not suitable for applications where a large Particle volume arises, such as from the exhaust gases of vehicle engines. In such a case, either a large number of filters are used or the Filters have to be regenerated frequently during use.

The invention has for its object a method of to create with the filter can be produced that have a large filter capacity.

The task is with those characterized in claim 1 Features solved, with gaps when winding the filter be provided that the penetration of particles with the  Allow gas into the interior of the filter. On this way not only the surface works, but that total filter volume as a deposit area for those in the gas contained particles. The gaps must be designed in this way be that the exhaust gases undergo multiple deflections and on this way particles that are not on the surface or the first layers were recorded, in lower layers can be captured.

The porosity is preferably achieved by simultaneous winding reached several strands of fiber, spaced apart be wrapped in cross layers. Here, the Fibers of a next layer over several fibers of the previous position without creating nodes. This has the advantage that an intermediate layer the two adjacent crossing fiber layers at a distance, which corresponds approximately to the fiber strand thickness, can tell apart. This is in one manufacturing technology simple type through the use a ring thread eye reached. The number of with the Ring strands guided fiber strands depends on the Diameter of the winding body and according to the desired one Distance between the fiber strands. Every wrap will exclusively from fibers lying next to each other, d. H. exist without knots.

The fibers of different layers with the same orientation are wound on hatch to close pore channels avoid the straight line of the winding body wall traverse. This creates zigzag channels through which particles can flow through the gas and thereby can deposit particles again and again.

For example, tubular filters can have multiple filters  be wrapped in one operation by a correspondingly long filter body and is successively separated into the filter body. Working time and material loss are reduced.

The fiber strands can consist of many thin filaments summarized rovings, the cross section of a Elementary is preferably less than 10 microns thick. A Such fiber strand has the advantage that Variety of very thin filaments Deposition area for the particles is greatly increased. Its effect is particularly noticeable when the Fiber is loosely wound, so that the gas with small Particles can also flow through fiber strands. At tubular filters also have an effect in this regard a larger diameter is advantageous.

However, it is also possible to use a yarn as fiber strands to use thin, twisted filaments. The yarn will round its even in the wound state keep round cross section in the winding body, see above that the formation of the flow channels between fiber strands and fiber layers come into play better and through the choice Yarn thickness can be determined reproducibly.

For the use of a manufactured according to the invention Filters for cleaning particles, in particular Soot particles, fibers are made of temperature-resistant Materials used, especially ceramics, silicon or glass. Such fibers form a soft one elastic filter body, which is generally not is self-supporting. By introducing auxiliary fibers, such as Metal, especially steel fibers can form the winding body sufficient rigidity to be given to the Give the winding body a self-supporting character.  

The auxiliary fibers can be coiled with the other fibers be so that the filter body evenly with auxiliary fibers is enforced. But it is also possible to use the auxiliary fibers either wound or processed into a network, preferably on the surfaces of the filter body Mistake. In any case, the auxiliary fiber winding or Network at the same time as a filter material on which deposit the particles in the same way as with the other fibers can.

The invention is based on Embodiments explained in more detail. In the drawing are in

Fig. 1 shows a first example,

Fig. 2 shows a detail from Fig. 1 and

Fig. 3 shows a second example schematically.

The method can be carried out using any method known in winding technology. In Fig. 1, a yarn eyelet (10) is for example shown with three adjacent fiber strands (11) which are wound around a rotating about the axis of mandrel (12). The fiber strands ( 11 ) are each held at intervals ( 13 ) so that a width ( 14 ) is coated per winding which is greater than the sum of the diameters of the three fibers.

The first winding layer ( 15 ) is placed approximately at an angle of 60 °. A second layer is laid crosswise at minus 60 °. The third layer can then again have a different orientation, which neither corresponds to the first nor to the second layer. If the third ply is also 60 °, as the first ply is to be laid, then the fiber strands are placed on the hatch in relation to the previous ply on the same position, as shown in broken lines under the reference number ( 16 ).

The result of such a winding pattern is shown in FIG. 2 as a greatly enlarged detail, the fibers of different orientations being drawn at right angles to simplify the illustration. The fibers ( 20 ) wound at a distance and on the hatch form pore chambers ( 21 ), all of which are connected to one another, but do not form any openings crossing the filter wall in a straight line. An exhaust gas stream ( 22 ) is therefore guided in a zigzag shape within these chambers ( 21 ) or channels, which are large enough on the one hand to allow the particles contained in the gas ( 22 ) to pass through and on the other hand small enough to allow these particles to pass through them To be able to hold the filter ( 23 ) with the fibers ( 20 ). The effective filtering surface thus extends to the surface of all fiber strands ( 11 or 20 ) of the filter body.

A fiber strand ( 11 ) consists of several filaments ( 18 ) which are bundled together to form a fiber strand or roving ( 11 ). In the example according to FIG. 2, the fiber strands ( 20 ) consist of filaments ( 24 ) twisted into a yarn.

With a loose thread guide, the filaments ( 18 or 24 ) are not pressed so close together, so that gases ( 22 ) can also flow through a fiber strand ( 11 or 20 ) and thus pull in smaller particles that are held on filaments . This extends the effective filter area to the surface of the filaments.

In Fig. 3, an example is shown in which a tubular filter is wound using an annular yarn eyelet 30 39. The ring thread eye 30 has six bores 31 , through each of which a fiber strand 32 is guided, which are guided over castors ( 33 ).

The number of fiber strands ( 32 ) to be wound together depends on the desired distance ( 13 , FIG. 1) between the fiber strands ( 32 ) on the winding body ( 39 ) and the diameter of the winding body ( 39 ).

The mandrel consists of a mandrel core ( 37 ) around which sleeve elements ( 38 ) are placed. The fiber strands ( 32 ) are wound onto the sleeve segments ( 38 ) by rotating the mandrel ( 37 , 38 ) in the direction of the arrow and displacing the ring thread eye ( 30 ) in the axial direction.

About the resulting speed resulting from the Combine the speed of rotation of the mandrel and the Feeding the thread eye results in the winding angle certainly. The angles are chosen so that the fibers each layer deals with the fibers of the adjacent fibers cross.

Another parameter to consider is the fiber draw during the winding process. The looser the fiber or the fiber strand is guided, the softer the bobbin and the looser the fiber strand and thus the element threads. With loose fiber tension, however, the fiber strands flatten in cross section, so that the chambers ( 21 ) are flatter.

example 1

In order to produce a tubular filter for exhaust gases, a detachable mandrel ( 37 , 38 ) of 5 cm in cross knife was pulled through a ring thread eye with a certain pushing and rotating speed, which led 12 fiber strands. Each strand of fiber consisted of approximately 6,000 7 µm elementary filaments made of silicon oxide, which were bundled together to form rovings. The 12 rovings were placed on the mandrel at a distance of approx. 2 mm from each other. The rovings were wound in 45 ° cross layers up to a wall thickness of the tubular filter of approximately F5 mm. During the winding process, the fiber draw / roving was approximately 200 g.

As a result, it was found that after the Pulling the winding body from the mandrel a soft, deformable winding body was created, the wall was compressible. The fiber strands were loose in it and spaced apart so that from a porous Could be spoken.

Example 2

A network of 2 to 3 mm was placed on the cylindrical mandrel Mesh size wrapped in 0.2 mm thick steel wire, whereby a sleeve was placed at both ends. With a wire, the network was at one end anchored around the sleeve. Then was in the same Winding process as in Example 1 silicon oxide fibers on the Network wound up. Finally, was around the bobbin a second network with the same characteristics as the first one placed the winding body and at the ends with a Anchored around the sleeve. This filter was after pulling out the mandrel a stiffness that was sufficient to the filter body without additional  To be able to use support measures. Have filter tests with exhaust gases from internal combustion engines result in the filter across the entire cross section contained soot particles that were retained including on the steel fibers.

Example 3

A filter body was wound on a mandrel according to FIG. 3 with a ring thread eye for 12 fiber strands made of 0.43 mm thick ceramic yarn with more than 6,000 thin elementary threads evenly distributed over the circumference. The ring thread eye simultaneously guided 4 steel wires of 0.5 mm diameter, regularly distributed between the yarn guides. The 16 fiber strands were wound onto the mandrel in 24 layers in the manner as in Example 2. The wall thickness of the finished package was approximately 3 mm.

With a fiber draw of approx. 200 g per ceramic fiber and approx. The one pulled from the mandrel reached 300 g per steel fiber Bobbins related to the others Process parameters have sufficient rigidity, whereby the ceramic fiber braid has a loose, pore-forming structure would have. A depth filter effect was found be one in both possible directions equally effective filtering through the whole Cross section of the filter was observed.

Claims (12)

1. A method for winding particle filters for gases, in which the fibers are wound around a releasable mandrel, characterized in that the fibers ( 11 , 20 ) are guided so that the winding body ( 23 ) has a porosity required for a depth filter effect ( 21 ) having. 2. The method according to claim 1, characterized in that a plurality of fiber strands ( 11 ) are wound simultaneously and at a distance ( 13 ) from one another in cross layers ( 15 ). 3. The method according to claim 1 or 2, characterized in that the fibers ( 11 , 18 ) are wound loosely. 4. The method according to any one of the preceding claims, characterized in that fibers of different layers ( 15 ) of the same orientation on hatch ( 16 ) are wound. 5. The method according to any one of the preceding claims, characterized in that the number of fiber strands ( 11 , 20 ) is selected so that they fill the filter width together with the intermediate distances ( 13 ). 6. The method according to any one of the preceding claims, characterized in that the fiber strands rovings ( 11 ) or yarns ( 20 ) are made of very thin filaments ( 18 or 24 ). 7. The method according to any one of the preceding claims, characterized in that the filaments ( 18 , 24 ) in the range of a few microns, preferably less than 10 microns thick. 8. The method according to the preceding claims, characterized in that fibers ( 20 ) made of ceramic, glass or similar temperature-resistant material are used for the production of filters ( 23 ) for exhaust gases. 9. The method according to claim 8, characterized in that in addition to the fibers ( 11 ) according to claim 7, auxiliary fibers ( 19 ) of higher stiffness, in particular metal fibers are used, which are introduced into the winding body that they give the winding body sufficient stiffness. 10. The method according to claim 9, characterized in that the auxiliary fibers ( 19 ) with the other fibers ( 11 ) are co-wound. 11. Particle filter made of wound fibers produced by the method according to claim 1, characterized in that the filter ( 23 ) forms a porous body with depth filter effect by open and loose winding. 12. Filter according to claim 11, characterized in that the porous winding body is self-supporting by including fibers ( 19 ) of higher rigidity.