CS247056B2 - Insertion piece for a steel cover of the elbow in an exhaust piping for the catalic purification of compression engines exhaust gases - Google Patents

Abstract

1. A catalytic filter for the purification of diesel engine exhaust gas, consisting of layers which are arranged in a pile to produce a gas-permeable package, or are wound up spirally to produce a gas-permeable body, the package or the wound body being sealed at the opposite front faces by cover means so that a sealed front face section is opposite an open front face section, characterised in that the layers consist of temperature- and corrosionresistant metal, and either a) in each case one layer of a wavy or folded screen cloth alternates with in each case one flat, closed cover layer, or b) in each case one layer of a wavy or folded screen cloth alternates with in each case one flat perforated cover layer, or c) in each case one layer of a wavy or folded sheet alternates with in each case one flat perforated cover layer and the filter is coated with a catalysis-promoting metal oxide, with filling of the cross-sections of the openings defined according to a), b) and c), and the oxide layer is designed to be permeable to gas.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust pipe liner for a catalytic purification of diesel engine exhaust.

In the context of declining world oil reserves, petroleum products and hence propellants for internal combustion engines are becoming more expensive. The aim is therefore to design engines with the lowest possible fuel consumption. An alternative solution to this problem is a diesel engine with at least about 5% higher efficiency than petrol fueled engines. In addition, so-called low oil concepts for gasoline engines are known, but these are not yet fully mature in construction.

The most common diesel engines are subject to the obligation to adhere to all applicable exhaust gas emission limits without a catalytic converter. However, this does not exclude the fact that diesel engines often contaminate the environment and that a percentage increase in the permissible values could create a real problem.

Diesel engines emit carbon black particles, possibly the finest drop of condensate or conglomerate particles, in addition to pollutants emitted by petrol engines such as carbon monoxide, hydrocarbons and nitrogen oxides, depending on their operation. These "particulates" are particles particularly rich in condensed polynuclear hydrocarbons, some of which have been found to be carcinogenic. The emitted substances also include aldehydes, which contribute to odor contamination of the surroundings.

In many countries, such as the United States of America, care is now being taken to include limit values for pollutants and particulates, ie particles in diesel exhaust, which can no longer be achieved by engine-related measures.

Although, for example, a reduction in NO.- emissions can be achieved by means of exhaust gas recirculation _; but this also leads to an excessive increase in particulates.

Other solutions to reduce the amount of pollutants from diesel exhaust gases suggest trapping soot and condensate particles in particulate traps. However, since the exhaust gas temperatures of diesel engines are usually not sufficient to burn soot - at least 450 ° C required - care should be taken to increase the exhaust gas temperature to regenerate the separators to prevent soot and condensate accumulation and thus clogging. separators. This can be done, inter alia, by mixing the air / fuel mixture periodically with the fats to achieve a higher flue gas temperature. However, mixing the air mixture and the fuel mixture is associated with additional fuel consumption and would partially undermine the advantages of the diesel engine.

In addition, ignition of accumulated soot or condensate particles can lead to uncontrolled or even explosive combustion and, in turn, to destruction of the separator or the entire exhaust system. The volatile hydrocarbons contained in the exhaust gas of diesel engines, carbon monoxide as well as odor pollutants such as aldehydes cannot, of course, be separated by sedimentation or the like; catalytic conversion is required to remove them.

While it would be possible to use a catalyst for degrading said pollutants, for example based on a monolithic ceramic reinforcing body, see USP 3,597,165, such an arrangement would be slowly soaked by the carbon blacks and lost due to their fastening relatively far from the engine. therefore, often quickly their effectiveness. However, the particulates can easily pass through the channels of the reinforcement body without breaking down.

Other devices additionally assist with the use of a catalyst for filtering off the soot and condensate particles. This filter is cleaned mechanically by shaking the particles, see brit. However, there is still the problem that the particles do not practically react on the post-catalyst.

The invention therefore relates to an exhaust pipe liner for catalytic purification of diesel engine exhaust gases made of chromium steel containing aluminum resistant to temperature and corrosion and with a catalyst support coated with a catalytically active material, consisting of a coil which:. It has a planar face which has opposing planar faces, the sections being formed between opposite layers of the coil, which are closed by a cover means, and an open section is formed on the face opposite to the covered section on one face.

The individual layers of the coil are formed from undulating and flat mesh.

In an alternative embodiment, the individual layers of coil are formed of corrugated sheet and flat mesh.

According to another embodiment, the individual layers are formed of corrugated mesh and a flat sheet.

The covering means closing each section is made of a ceramic material, for example a hardened mass of talc and water glass or a weldable material, for example chromium steel.

The cover means may be formed by a cap-like template abutting and fastened to the face of the coil and partially enclosing the coil housing, the holes thereof forming sections between the individual coil layers.

Above the at least one layer of netting, a shape flange can be slid on the front

U, adapted to the respective profile, which is mounted on it.

Welding or soldering the flanges to the layers in a flat or spot pattern has proven to be a good solution to fix the mesh configuration. The layers made of alternating at least one corrugated layer or corrugated mesh and at least one straight closed or intermittent cover layer are preferably welded or soldered for further mechanical fastening at the front.

The mesh configurations thus produced can be coated in a conventional manner, for example by electroplating or impregnating with a noble metal and / or a non-noble metal. However, they can also be processed into a carrier matrix impregnable with active metal catalyst solutions coated with a material customary as a catalyst support material. According to one embodiment of the liner, the individual layers are coated on their surface with a catalysing support, most often a large surface metal oxide, such as active aluminum oxide A1 ₍ O _3), to the extent that the cross-sectional area of the interrupted layers, i.e. it remains free, i.e. part of the cross-section of the openings of the intermittent layers is closed by said metal oxide.

Another embodiment with a particularly intensive filtering effect is that the entire cross section of the interrupted mesh layer opening is coated with a porous catalysing layer of catalysing metal, for example active alumina. The filtration effect is adjusted here according to the porosity of the oxide layer.

Other catalysers such as cerium, zirconium, iron, nickel, rare earths or combinations thereof may also be incorporated into the metal oxide as catalysing aids. The carrier intermediate layer is then provided with its own catalyst in a conventional manner.

The cover means used to close the end faces is made of a material resistant to temperature and corrosion. The covering means may consist of a ceramic mass, a weldable filler or a solder or a abutting and / or attached template, which is optionally formed as a perforated mask partially enclosing the shell of the roll.

Seals made of ceramic material, which consists of talc and water glass, are particularly suitable as covering means for the end face sections. With this mass, the individual channels are so clogged that the closed channel end and the open channel end are alternately opposite one another, i.e., in the spiral net configuration, the closed section of the end faces adjoins the two open sections of the end faces and vice versa. ,

The covering of the end faces can also be effected by forming a template which is abutted and / or fixed to the end faces, or in the form of a perforated or slotted mask, which partially surrounds the coil shell, which serves to close the respective ends of the channels.

The mask may be arranged such that, in the spirally wound, exclusively mesh-made matrix, it leaves alternately covered and uncovered sections corresponding to the width of twice the ripple amplitude, with open and closed sections arranged opposite each other on opposite faces. This achieves that the exhaust gas entering in one open section of the face cannot exit at a section opposite that face but must be forced through a gas-permeable partition matrix ·

The helical segments of the apertures may extend only close to the circumference of the coil, and it must be ensured that an appropriate overlap of the closed portions of the faces is always provided to prevent the by-pass effect, i.e. the by-pass effect. It is also possible to arrange segmented areas with spirally arranged slots using odd numbers.

The faces of the type described above may be sealed with welding material or solder.

The netting used may be a strip having a mesh size of from 0.25 to 0.025, preferably 0.1 to 0.05 mm, and a wire thickness of 0.15 to 0.025, preferably 0.1 to 0.05, in particular 0, 07 mm.

Metal strips with a wall thickness of less than 0.15 mm are used as closed cover layers.

The width and height of the cells surrounded by alternately arranged smooth and undulating layers should not be less than 0.5 mm.

The corrugated layer may have different shapes. Preferably, it has a sine wave or involute shape or a rectangular or square shape.

Sheets and netting, which consist of an alloy of iron, chromium, aluminum and optionally cerium or yttrl and conventional alloying additives, or other materials resistant to heat and opal, are particularly suitable for the mesh arrangement used.

For mechanical stabilization, the mesh arrangement in the form of a roll can be carried out in a steel sheath open on the face and can be firmly connected to it by soldering or welding. Advantageously, the thermal insulation of the steel jacket may be a high temperature insulating material.

If the filter catalyst needs to be installed, for example because of space requirements, in places with cooler exhaust temperatures or if carbon black and particulates are to be started during the cold start phase, then it may be advantageous to install power supplies to the filter catalyst. continuous or periodic galvanic heating of layers.

The netting arrangement according to the invention can be used in exhaust gas purifiers, as a filter for dust and / or aerosols and / or as a support matrix for catalysts. The exhaust gas cleaning of diesel engines can be considered a preferred field of application. In this case, the filter catalyst is located in the exhaust manifold directly on the engine block. The degradation of the oxidizable volatile components of the exhaust gas can be carried out simultaneously by arranging a suitable catalytic coating. However, it is also possible to incorporate a normal catalyst or a catalyst produced according to the invention as an embodiment formed exclusively as a filter arrangement.

The invention will now be described in more detail with reference to the various fully effective embodiments shown in the drawings.

The drawings show:

Fig. 1a is a plan view and Fig. 1b a front view of a cylindrical roll in which the end face closed by a stopper faces an open section of the customs surface;

FIGS. 2a and 2c show two possible forms of cover templates for the case where the wound matrix, i.e., the coil, consists, in addition to the outer wrapper, entirely of netting as well as a partial cross-sectional view of such a coil in FIG. 2b.

FIG. 3 shows the various combination possibilities of the netting or sheeting arrangement;

FIG. 4 shows a schematic arrangement of a netting with power supply for galvanic heating of layers.

As can be seen from FIG. 1, the embodiment according to the invention consists of spirally wound layers of a roll of plain netting 12 or smooth sheet metal 13 and a corrugated netting 12. The channels formed in this way are closed on one face in one section, while on a face opposite this section 1 is a second section 2 that is open. The closure means 3, in this case a ceramic plug, consisting, for example, of a hardened mass of a mixture of talc and water glass, serves as a closure. The exhaust gas flowing in the direction of the arrow 4 enters the face with the open channels of the filter, penetrates through the layers 5 of the mesh 12 and exits at the other end through the open side of the channels.

For use in the exhaust pipe system of motor vehicles, the coil is fitted into and connected to the metal casing 6.

However, an apertured or slotted mask is also suitable as a cover means 3 for partially closing the second faces 2, as shown in FIG. 2.

Giant. 2a and 2c show alternative embodiments of a slit mask. These cover the annular segments 7, 11 of the face, while the uncovered segments 8, 10 are closed on opposite faces. Giant. 2b shows a cross-sectional view of a cylindrical configuration of a mesh 12 in which the flow of exhaust exhaust gas is schematically illustrated by arrows 4 through the layers 5 of the mesh 12. The slit mask used for covering can be formed as a cap 9 and can be firmly connected to the wrap by welding or fusing.

As shown in FIG. 3, there are various combinational possibilities for forming the mesh 12 and the sheet 13. Thus, the corrugated or shirred layers may consist of the mesh 12 and the covering layer of a smooth metal foil - sheet 13 - or the corrugated layers may consist of metal foil - sheet 13 -. However, there is also the possibility of making both layers of mesh 12.

As mentioned above, it may be advantageous for the filter catalyst to be preheated by the ignition lock and the timer relay and thus, especially during the cold start phase of the diesel engine, to eliminate the amount of soot and particulates formed. This can also be used during normal phases of operation, for example, when the exhaust gas temperature is too low, or if the soot build-up on the filter is too large, resulting in increased pressure losses in the exhaust pipe system.

Fig. 4 schematically illustrates the possibility of galvanically heating a filter catalyst according to the invention by means of a normal car battery. Thus, for example, the power circuit can be switched on automatically during start-up, for example for 30 seconds. Then either the timing relay or the differential pressure switch takes over the control function over the current flow.

Claims (6)

CLAIMS 1. An exhaust pipe elbow steel liner for catalytic exhaust gas cleaning of compression-ignition engines, consisting of chromium steel, containing aluminum, resistant to temperature and corrosion, and having a catalyst support coated with catalytically active material, consisting of a roll having opposed planar faces, characterized characterized in that sections (1, 2) are formed on the opposite faces between the individual layers of the coil, which are closed by a cover means (3), wherein OF THE INVENTION against the covered section (1) on one face is formed on the face opposite the other section (2) open. Insert according to Claim 1, characterized in that the individual layers of the coil are formed from a corrugated and flat mesh (12). 3. Insert according to claim 1, characterized in that the individual layers are made of corrugated sheet (13) and flat mesh (12). 4. Insert according to claim 1, characterized in that the individual layers are formed from 2 4 7 O 5 6 corrugated mesh (12) and flat sheet (13). 5. Insert according to claim 1, characterized in that the covering means (3) is made of a ceramic material, for example a hardened mixture of talc and water glass or of a weldable material, for example chromium steel. Insert according to one of Claims 1 to 5, characterized in that the covering means (3) consists of a cap-shaped template (9) abutting and fastened to the front surface of the coil and partially enclosing the coil shell, the holes of which form sections (1, 2) .