Filter for particles, made of metal foil

REPUBLIC

POLAND

<img file="PL197130B1_D0001.tif" />

Patent Office of the Republic of Poland (12) PATENT DESCRIPTION (19) PL (11) 197130 B1 (²¹) Application number: ³⁵²³⁵⁵ (13) (22) Date of report: May 22, 2000 &lt;⁵¹ &gt;^lnŁCI·

B01D 46/52 (2006.01) (86) Date and number of the international application:

22.05.2000, PCT / EP00 / 04640 (87) Date and publication number of the international application:

07.12.2000, WO00 / 72944 PCT Gazette No. 49/00 (54) Particle filter made of metal and the method of its production

<td>(30) Priority: 1999-05-28, DE, 19924584.3</td><td>(73) The right holder of the patent: EMITEC GESELLSCHAFT FOR EMISSIONSTECHNOLOGIE MBH, Lohmar, DE</td>

<td>(43) Application was announced: 11.08.2003 BUP 16/03</td><td>(72) Inventor (s): Wolfgang Maus, Bergisch Giadbach, DE</td>

<td>(45) The grant of the patent was announced: March 31, 2008 WUP 03/08</td><td>(74) Representative: Łazewska Sławomir, Łazewska and Łazewski</td>

(57) 1. A metal particle filter having fluid openings immediately adjacent to each other, each of the channels having at least one inlet and one outlet, with one first inlet channel and one second discharge channel adjacent thereto, the first channel being open. an inlet section at the first face of the particle filter which extends at least partially downstream of the first channel, the first channel has an inlet cross section opposite the second face downstream of the end, characterized in that:

- the ending (13, 23) of the first inlet channel (2, 19) practically completely closes the path of the flowing fluid (10, 18) ....................... .............

11. Method for the manufacture of metal particle filters, characterized in that firstly a metal foil is pulled from at least one endless hopper (28), then an adhesive material (30), in particular in the form of a strip, is applied, after which recesses are formed in the metal foil. channels (29), the foil layers (29) are rolled or arranged so as to form opposing first channels (2, 19) and second channels (3, 4, 21), the first channel (2, 19) has an open inlet section (11) from the first face (12) leading at least partially into the first channel (2, 19) and at the same time ................... ...

FIG.1

<img file="PL197130B1_D0002.tif" />

5,6

PL 197 130 B1

Description of the invention

The present invention relates to a metal particle filter and a method of manufacturing the filter. Filters of this type are used in particular in diesel engines to purify exhaust gases, e.g. as catalysts.

Patent EP 0 134 002 discloses an exhaust gas filter for a diesel engine made of a fabric or wire, as well as a method of its manufacture. The said exhaust gas filter for a diesel engine is constructed of stacked layers or it is shaped like a spiral ring. The layer consists of spacers made of wavy or pleated mesh-like fabric and a closed or discontinuous coating. Both faces of the exhaust gas filter of a diesel engine are shaped such that a part of the closed face is situated opposite a part of the open face, the part forming the face being clamped. The corrugated or corrugated spacer is here pressed against the flat spacer.

The object of the present invention was to provide a structure for the particle filter and a method for its production which allows the production of the particle filters to be simplified and at the same time allows to obtain a large active surface inside the filter.

The invention therefore relates to a metal particle filter comprising fluid passageways located immediately adjacent to each other, each of the channels having at least one inlet and one outlet, with one first inlet channel and one second discharge channel adjacent thereto. the first channel has an open inlet section at a first face of the particle filter which extends at least partially into the first channel, the first channel having an inlet cross section opposite the second face downstream, characterized in that:

- the end of the first inlet channel practically completely closes the path of the flowing fluid,

- at least one of the walls forming the first channel has a perforation in the form of filter passages leading to the second channel,

- the second drainage channel has an open outlet section at least approximately corresponding to the inlet section,

- the walls of the first and second channels are made of metal foil and

- the filter passages are the only inlet to the second channel.

In one preferred embodiment of the particle filter according to the invention, its first channels and the second channels are of the same shape, but are arranged in opposite directions to each other.

In another preferred embodiment of the particle filter according to the invention, the first channels and the second channels alternate to form honeycomb structures.

In yet another preferred embodiment of the particle filter according to the invention, the walls of the first and second channels are made of only one metal foil.

In a further preferred embodiment of the particle filter according to the invention, the first and / or the second channel have a tapered cross-section. In a particularly preferred embodiment of the particle filter according to the invention, the tapered cross section is wedge-shaped.

In a further advantageous embodiment of the particle filter according to the invention, the filter passage is an opening in the metal foil with a diameter of 3 to 25 µm, preferably 5 µm.

In a further preferred embodiment, the particle filter according to the invention has from 80,000 to 120,000 passages per square meter of wall.

In another preferred embodiment of the particle filter according to the invention, the wall with filter passages has a thickness of 20 to 65 µm, preferably 30 to 40 µm.

In yet another preferred embodiment, the particle filter according to the invention is coated.

The invention also relates to a method for the production of metal particle filters, in particular particle filters according to the invention, characterized in that first a metal foil is pulled out of at least one endless hopper, then an adhesive material, in particular in the form of a strip, is applied, and then channel recesses are formed in the metal foil, the layers of metal foil are rolled or arranged so that opposing first and second channels are formed, the first channel has an open inlet section leading from the first end side

At least partially to the first channel and at the same time the first channel has an end opposite to the position of the inlet cross-section, adjacent to the second face, and finally permanently connected contact surfaces of the channels, therefore the particle filter is made of metal foil only.

In a preferred embodiment of the method according to the invention, the coating is applied to the metal foil before or after the manufacture of the metal particle filter.

In another preferred embodiment of the method according to the invention, the metal foil is perforated before or after the production of the metal particle filter or the coating of the metal foil.

In the particle filter according to the invention, due to the fact that the walls of the first and second channels are made of a metal foil, they have a sufficiently large surface in contact with the fluid stream. While when a fabric made of wire is used, the active surface is only the individual fibers of the fabric, the wall forming the surface of the first channel is in the form of a continuous surface, except for perforation. The perforations in the filter passages connecting to the second channel furthermore have surfaces with which the fluid may contact. In contrast to a wire cloth (mesh), such a perforated wall therefore has a larger surface area, which, for example, with a suitable coating or with appropriate selection of the material for the metal foil, has a large active surface. This makes it possible to induce catalytic or other reactions, or also to extend the applications of this type of particle filter.

The aforementioned advantage of a large active surface is combined with the advantageous production of this type of particle filter with fewer processing steps. The necessary perforations are provided, for example, in a metal foil. The shaping of the individual channels is preferably performed in one operation, irrespective of whether the metal foil is perforated or not. For example, it is advantageous for the individual walls of the already formed channels to be perforated, so that during the manufacturing process the metal foil or the metal foil can be processed independently of the way it is arranged and positioned.

Moreover, the perforation of the metal foil enables the exact, desired final positioning of the passages in the finished particle filter. While there is a risk of fiber displacement in the case of a wire mesh fabric, this is not possible with perforation . The use of perforation as filter passages allows the density of the perforation through the metal foil and hence the shape of the channel wall to be varied, as well as the diameter of the holes forming the perforation. This applies in particular when different degrees of filtration are created in the particle filter.

In order to avoid high pressure losses caused by the particle filter, its second channel has a suitably selected free outlet cross-section adapted to the inlet cross-section. Thereby it is achieved that the pressure drop is controlled to a certain extent in proportion to the number and dimensions of the holes forming the perforation. According to an advantageous further variant of the solution adopted, the particle filter has an end of the first channel shaped such that it is obstructed by the flow of fluid. Thus, the passages of the filter constitute the only entry to the second channel. The end of the first channel serves as a barrier so that the fluid is only forced through the passages of the filter. The filter passages in the fluid stream will therefore accumulate in the end zone of the first channel. This phenomenon is intensified, for example, by the use of a special mesh in the end zone. By appropriately shaping the flow in the end zone of the channel, it is possible to make use of the stagnation zone that arises there in such a way that the particles do reach there, but ultimately do not settle permanently. As a result, the filter passages remain unobstructed and the particle filter itself requires fewer regeneration cycles. For regeneration purposes, the particle filter, in particular in the end zone of the closures, can be provided with suitable regenerative systems, such as, for example, electric heating, a catalytic coating or the like.

To simplify the manufacture of the particle filter, both its channels have the same shape, but are opposite to each other. This requires the use of only one tool for the production of the metal foil, and in the case of a multi-layer particle filter, the individual metal foils can first be processed in one direction and only then alternately turned against one another. Preferably, the first and second channels have a honeycomb structure, the first and second channels being interchangeable.

PL 197 130 B1

According to a further advantageous embodiment, the walls of the first and second channel are formed from a single metal foil. This makes it possible to unwind the metal foil supplied in the form of a roll, and then subject it to appropriate perforation, as well as, at the next processing station, to give the desired shape by means of plastic working. The metal foil in turn is rolled up or layered to form a particle filter. Only before this processing operation is performed, it is necessary to cut the metal foil from the coil. The particle filter made by the rolling method, or composed of successive layers, at the points of mutual contact of successive walls, is characterized by welds made by brazing.

It is preferable to use a film with a suitable coating before it is used for processing. This coating may exhibit catalytic properties, thanks to which, additionally, the surface of the particle filter is significantly increased as a result of applying such a coating. Alternatively, the coating used may consist of a connecting material, such as solder, to enable permanently abutting filter walls to be joined. For this purpose, e.g. the material forming the joint is applied to the surface of the metal foil in the form of strips before the particle filter is made. It is also possible to apply a joint-forming material to the surface of the metal foil, e.g. in the form of a suitable coating.

In order to increase the active surface of the particle filter, it has furthermore proven to be advantageous to provide a first and / or a second channel with a tapered cross-section. A wedge-shaped taper is preferred in this case. For the first channel, the tapered cross-section acts as an inlet and thus a reduction in pressure losses is achieved. In addition, the active surface of the filter that acts on the liquid substance is increased, as its stream flows obliquely towards the surface. At the same time, this enables the particles that accumulate at the openings of the filter passages to be washed out by the flow of flowing fluid. As a result, the particles precipitated from the fluid move towards the zone closing the first channel. The movement of the particles is assisted by the fact that the opposite walls of the metal filter are properly perforated. Along these walls, a jet layer is thus formed against which the fluid is moving. Due to the turbulence arising in the central area of ​​this type of channel, the particles are carried along it to the end zone where they can settle.

Another important parameter of the particle filter is the pressure loss resulting from its presence. In order to be able to produce a large surface with a high filtering effect, but without a large pressure drop, it is important - as tests have shown - to properly select the diameter of the filter passages. It has proved advantageous for the filter passage to have the shape of a hole in the metal foil with a diameter ranging from 3 to 25 µm, in particular 5 µm. With such a selected diameter, it is possible to optimize other system parameters operating in the opposite direction. The supportive effect is achieved when the particle filter has between 80,000 and 120,000 filter passages per 1 m² wall surface. The square meter of the filter wall is defined here in that it is the surface against which the stream of filtered fluid can contact.

Since the particle filter is exposed to high temperatures, in particular in automotive applications, it is imperative that it be temperature-stable and also that it is stable under the action of mechanical vibrations. This is possible with the use of a metal foil which is suitable for making walls with a thickness of 20 to 65 µm, preferably 30 to 40 µm with filter passes. In particular, the range of wall thicknesses from 30 to 40 [mu] m makes it possible, on the one hand, to produce channels without great effort for obtaining particularly light filters, which, however, are nevertheless distinguished by sufficient stability and resistance under the conditions of use.

It has also proven advantageous if the coating of the particle filter is applied after the channels have been made.

A method for producing particle filters using a metal foil was also found, with which it was possible in particular to make the filter described above. This method consists of the following operations:

- pulling the metal foil out of at least one endless hopper,

- application of the binder material, in particular in the form of a strip,

- shaping the channel cavities in the metal foil,

- rolling or arranging the layers of the metal foil so that opposing first and second channels are formed, the first channel having an open inlet section from a first face side of an element extending at least partially into the first channel, the first channel being

The channel has an end opposite to the inlet section, adjacent to the other end face, and a permanent connection of adjoining portions of the contact surfaces of the channels, so that the particle filter is made solely of a metal foil.

In one preferred embodiment, the method of producing particle filters can be extended by applying a coating to the metal foil before or after the above operations. A further alternative embodiment of an extended version of the method of the above-described method comprises perforation of the metal foil either before or after the operations mentioned above are performed.

The subject of the invention in the exemplary embodiments is shown in the drawing, in which:

Fig. 1 shows a particle filter made of laminated metal foil, Fig. 2 shows a second constructional solution of a particle filter made of one metal foil, Fig. 3 shows a variant of perforation in the metal foil of a particle filter and Fig. 4 shows a production line for producing a particle filter made of metal foil.

Figure 1 shows a first design embodiment of a particle filter. It consists of a first inlet channel 2, a second discharge channel 3 and a third discharge channel 4. It is made of a metal foil 5 arranged in layers. The metal foil 5 forms the walls 6 of channels 2, 3 and 4. The first wall 7 and the second wall 8, which together form the first channel 2, have a first perforation 9 provided as filter nozzles leading to the second channel 3 and to the third channel 4. The fluid indicated by the arrow 10 flowing through the particle filter 1 enters the open inlet section. 11 from the first face 12 of the particle filter 1. The inlet cross section leads into the interior of the first channel 2. Due to the fact that the first channel 2 has an end 13 opposite the inlet section 11 and extending to the face 14, this fluid can be forced through the perforation 9. A back pressure is generated in the end region 13 which directs the fluid into the channels 3 and 4. End 13, according to the illustrated embodiment, has no perforation and is therefore closed to the fluid 10 in a gastight manner. In another embodiment not shown here, the end 13 is also provided with a perforation. This makes it possible to direct the fluid 10 along the entire length of the channel 2. According to a further advantageous embodiment, perforation is provided only in the first end zone A 13, while the second end zone B 13 has no perforation. Thanks to this, due to the lack of flow, the second zone B functions as a dead zone, and at the same time serves as a place for particles to accumulate in it, in the first channel 2.

The second channel 3 has an open outlet section 15, which is equivalent to an open inlet section 11. The open inlet sections 11 and the open outlet section 15 shown here have the advantage that they act on the fluid by narrowing or increasing the cross-sectional area like nozzles. or diffusers. This helps to minimize the pressure loss caused by the particle filter 1. However, the outlet section 15 can also be larger than the inlet section 11, thereby slowing the fluid flow. If, on the other hand, it is desired to increase the flow rate downstream of the particle filter, then the outlet section 15 can be made smaller compared to the inlet section 11.

Figure 2 shows a second particle filter 16. A second variant of the particle filter 16 is made of a single metal foil 17. A second type of fluid 18 containing the particles, indicated by an arrow, flows in the fourth drainage channel 19 through the second perforation 20 into the fifth drainage channel 21. Metal foil 17 it is folded so that it forms third type walls 22 of channels 19 and 21, as well as ends of channels 23. Channels 19 and 21 have a tapering cross-section. With this advantageous design, the cross-sections of the channels are wedge-shaped. In this way, it is possible to obtain a nozzle effect along the entire channel as well as to increase the size of the area in direct contact with the fluid stream per channel.

Figure 3 shows a foil cut 24 with a variant of the third type of perforation 25. In the shown cut 24 of the blank, the density of the filter passages 26 increases. This is achieved by varying the distance of the filter passages 26, as well as their number and diameter. As shown, fluid flows preferably into section 24 from the direction shown by the arrow. A fluid flow is obtained in the channel, advantageous over the entire length of the sector 24 shown.

FIG. 4 shows a preferred variant of the processing line 27 in which a method for making metal foil particle filters, in particular the inventive particle filters, is possible. To this end, a metal foil 29 is unrolled from an endless reservoir, in this case from a coil of metal foil 28. In the next technological operation, the surface of the metal foil 29 is nano6.

The binder 30 is applied. It is preferably applied in the form of strips, it is most expedient to apply the binder along those zones where the layers will be in contact with the purpose of joining them. In the next operation, the formation of the particle filter channels takes place. In the illustrated design, this is accomplished with the first press 31 and the second press 32. The first press 31 gives the film 28 the same shape as the press 32. However, they are correspondingly shifted by 180 ° to each other.

During the next technological operation, the formed fragments 33 of the metal foil 29 are separated from each other. The 180 [deg.] Alternating recesses make it possible that the shapes extruded in this way can be successively stacked. By stacking, the first and second channels are created. Although they have the same shape, they are opposite to each other. In turn, during a technological operation not shown in the drawing, the contact surfaces facing one another are permanently connected to each other, for example by brazing, which makes it possible to make the particle filter exclusively from a metal foil. In the next processing operation on the production line 27, perforation is performed in the particle filter 35 by means of a laser 34. Preferably, prior to perforation in the particle filter 35, a catalytic coating is applied to its surface, which consequently increases the active surface of the filter.