DE2239873A1 - Exhaust gas catalytic convertor - with cross flow catalyst enclosure and tapering plenum chambers - Google Patents

Abstract

The converter has the catalyst contained in a cross flow enclosure assembled for oppositely-dished upper and lower perforated plates having peripheral flanges sandwiched between peripheral flanges of oppositely-dished upper and lower housing plates jointly enclosing the enclosure, the plates being formed to provide inlet and outlet connections communicating with plenum chambers defined between the upper plates and the lower plates respectively. The enclosure is preferably inclined to define tapered plenum chambers adapted to give the regulated pressure gradient.

Description

Catalytic converter for fuel exhaust gases The invention looks at a catalytic converter for internal combustion engine exhaust gases which the exhaust gases are fed to an inlet chamber in a housing and through Catalyst bed held in a container in the housing occurs before it comes out of a Exit chamber from the housing.

The exhaust gases are treated in such catalytic converters, to convert their unwanted components into harmless form. To this The purpose is the catalytic converter in the exhaust system of the internal combustion engine incorporated, so that the exhaust gases emerging from the internal combustion engine are passed through the converter in this flow through a bed of catalytic material, through the carbon monoxide oxidizes and unburned hydrocarbons to carbon dioxide and water and / or Nitrogen oxides are reduced before the exhaust gases escape into the open.

Catalytic converters for internal combustion engine exhaust have different ones To meet requirements, if they are to be effective, a sufficient lifespan exhibit and are economical. The catalytic converter must be designed in this way be that it can be integrated into the exhaust system of the vehicle, for which purpose it ethe must have a relatively low height so that the necessary free space is available of the vehicle is complied with, but a catalyst bed must be sufficient Record volume to ensure effective treatment of the exhaust gases. Of the Catalytic converter must be light enough that it can be carried by the exhaust system can be, but on the other hand it must be designed in such a way that it is self-supporting and deformations resulting from the combined effect of the high operating temperature, which can be up to 880 ° C, and the pressure of the exhaust gases inside the converter, which can be up to 635 mm QS. Furthermore, with catalytic Converters in which the itatalytic material is in the form of spheres or spheres is used, the catalyst bed tightly packed during operation to keep, so that abrasion of the Katälysators by vibrations and dust formation during Passage of the exhaust gases is prevented. Third, it is desirable that the electricity of the exhaust gases through the catalyst bed is essentially evenly distributed over the bed takes place so that a maximum operating time of the catalyst and a optimal conversion of the exhaust gases is assured. Fourth, the catalytic converter must be designed so that different temperatures within the converter, which could cause local breaks are excluded. Fifth, the catalytic converters can be manufactured from relatively cheap materials, such as steel, so that high-temperature-resistant alloys are based on Nickel or cobalt bases are dispensable, which call the economic viability into question would. Furthermore, it must consist of as few parts as possible in order to be easy to manufacture and allow easy assembly.

The invention is based on the object of these numerous requirements for a cheap, reliable and economical latalytic converter fulfill.

According to the invention, this object is achieved in that the same Housing by two opposing arched upper and lower plates is formed and at a distance surround the container for the catalyst, which consists of two each other Opposite arched plates are formed which are over substantially over the circumference extending flanges bear against each other, which ç wipe similar substantially circumferentially extending flanges of the housing grip, the four plates being sealed against one another at their peripheral edges, and that the plates have at their opposite ends parts that at one end an exhaust gas inlet to a plenum chamber between the one housing plate and the adjacent container plate and at the other end an exhaust gas outlet from one Form a collecting chamber between the other plates of the housing or the container, the latter being provided with openings that hold back the catalytic material, However, allow the exhaust gases to pass through. The catalytic converter is essentially used thus formed from four sheet metal parts, between which only edge seals are required to the container for the catalytic material and the gas channels through the converter to form.

In a further embodiment of the invention it is provided that the Parts at the ends of the plates are substantially semi-cylindrical in shape, the Part on the upper housing plate with the concave surface facing downwards, the Part on the lower case plate with the concave surface facing up directed and the parts at the one ends of the container plates with the concave surface after directed downwards and the parts at their other ends with the concave surface after are directed above, with the three identically directed parts of the plates at one End interlocking and with the opposite part of the fourth plate the Form the exhaust gas inlet or the exhaust gas outlet with a substantially cylindrical shape.

According to a further feature of the invention, the container for the catalyst at substantially the same height and is to the longitudinal direction of the housing inclined.

It is useful if the curved parts of the upper and lower tank plates from the inlet side to the outlet side of the converter in increase or decrease in height.

Another feature of the connection is that supports are arranged essentially vertically between the container plates and these hold at a predetermined distance from each other and at their ends on the housing plates are set.

In this case it is sweckmäßig if the ends of the supports pass through aligned breakthroughs in the container plates and the housing plates occur and are welded to the housing plates.

In a preferred embodiment it is provided that the supports are provided with shoulders against which the inner surfaces of the container panels rest and at the breakthroughs outwardly directed lips are formed, which with on the ends of the supports put on reinforcing discs by a continuous Weld seam are connected.

It is also useful if the openings for receiving the supports lie in indentations of the housing plates, which are against the adjacent container plates issue.

According to a further feature of the invention it is provided that the Breakthroughs in the container plates through parts pressed out of these in an arc shape are formed.

In a preferred embodiment of the invention it is provided that above the upper housing plates an upper cover with a peripheral flange is provided over the sealed peripheral edges of the housing and container plates is bent, and a layer between the top cover and the top housing plate from heat-insulating material is provided.

It is useful if below the lower housing plate a cover is attached between this and the lower housing plate Layer of heat insulating material is provided.

In the drawings are exemplary embodiments of catalytic converters shown according to the invention.

In the drawing, FIG. 1 is a partially sectioned side view a first embodiment of a catalytic converter according to the invention, Fig. 2 is a plan view on a smaller scale of Fig. 1 with partially broken away Parts, Fig. 3 is a section along the line III-III in Fig. Lo Fig. 4 is a side view a second and preferred embodiment of a catalytic converter of the invention, FIG. 5 is a plan view of FIG. 4 with parts partially broken away, 6 shows a section along the line VI-VI in FIG. 50; FIG. 7 shows a section along the line VII, VII in FIG. 4, FIG. 8 shows an enlarged partial section along the line VIII-VIII in FIG. 5, FIG. 9 an enlarged plan view of part of FIGS. 5, 10 a section along the line X-X in Fig. 9, 11 shows an enlarged Partial side view along the line X I in Fig. 5 and Fig. 12 is an exploded view perspective view of the second embodiment of the catalytic converter according to FIGS. 4 to 11.

The drawings show the same, if need be, slight differences showing parts with the same Pezugzeicben.

The preferred embodiment is shown in Figures 4-12 and has a housing 10, which is preferably made of a high-grade stainless steel Chromium content is manufactured or consists of coated or plated rod, to be resistant to corrosion from salts and high temperature gases. The housing 10 of the converter consists of a curved top plate 12 and a curved lower plate 14, the substantially vertical side walls 16 and

18 indicate, on denea a circumferential flange 20 or 22 essentially is formed over the entire circumference.

A container 24 for the catalyst is inclined within the housing 10 arranged, which consists of an upper plate 26 and a lower plate 28. The upper plate 26 includes a perforated upper part 30, the distance from the upper housing plate 12 and has several at a regular distance from each other Contains formed openings 32 'of about 1.6 mm in size. In the same way is the lower plate 28 of the container with a bottom part provided with openings 34 is provided, which is at a distance from the lower housing plate 14 and has openings 262 Contains, the breakthroughs 32 'and 36' can have different shapes. For example they can be in the form of holes extending through the container plates or they can be formed by slotted openings, with outwards directed projections are formed, which in the direction of the a @ ftende gas flow are hollowed out, as shown in the first embodiment according to FIGS. 1-3 is.

In the preferred embodiment according to FIGS. 4-11 are arcuate Slots 32 'and 26' by cutting or slotting and stamping out sheet metal the plane of the plate formed 90 that rows of evenly spaced Arc-shaped slots are created that are 1.6 in height and 3.8 in width and a length of about 12.7 mm, with between consecutive in a row Slit a distance of 6.4 mm and between the individual rows a distance of 3.8 mm exist.

The panels 26 and 28 of the container 24 have impermeable side walls 28 and 40, which merge into peripheral flanges 42 and 44, which extend in the transverse direction extend outwards. The height of the side walls increases from one end of the plate 26 starting and increasing from the same end of the opposite plate 28 from, so that when joining the two plates 26 and 28 between them a Chamber 46 is formed, which builds essentially the same, but relatively is inclined to the housing plates 12 and 14, as shown in FIGS. 6 and 11 permit. In this way, the container 24 forms with the housing plates 12 and 14 a collecting chamber with progressively decreasing cross-section for the incoming exhaust gases, whereby a substantially constant pressure gradient is achieved and in the same way Way a collection chamber of progressively increasing cross-section for the outflowing Exhaust gases, a substantially constant pressure gradient also being achieved.

The chamber 46 of the container is filled with a suitable catalytic Material 48 filled, this material densely packed forming a catalyst bed.

The catalyst can be used in any form, but preferably it has the shape of spheres or is extruded, with a size of about 3.2 mm is wäblt and the catalyst is used with or without a carrier will. The catalytic material is preferably distributed in a carrier or impregnated in this, which optionally supports the catalytic effect. Any catalyst or both suitable for oxidation or reduction for oxidation and reduction can be used at operating temperatures up to 8800 q can be used for a longer period of time. It is desirable that the catalyst bed is relatively thin in order to keep the back pressure in the exhaust system low. It has been found that a catalyst bed about 50 mm deep is suitable. As shown in Fig. 8, the catalytic material 48 occupies the space between the arcuate one Schlitzm32 'a, however, is area large in order to be held back, so that he cannot escape from the container.

The peripheral flanges 20, 22, 42 and 44 of the housing plates 12 and 14 and the container plates 26 and 28 extend on the outside and form mutually abutting surfaces 20 ', 22', 42 'and 44' (FIG. 12) essentially over the entire scope. As shown in FIGS. 6, 7 and 11, they lie against one another abutting flanges 42 and 44 of the container 24 between the flanges 20 and 22 of Housing 10, so that a four-layer flange arrangement is formed is, which in a simple manner by an outer, essentially continuous circumferential weld seam 50 is sealed, whereby an inner and outer seal is created.

The catalytic material in the container 24 is thereby inside of the housing 10, with the side walls 38 and 40 of the container 24 at least at its ends inwardly spaced from the side walls 16 and 18 of the housing 10 have, eo that between these spaces 52 and 54 arise (Fig. 6).

The flanges of the housing 10 and the container 24 have substantially semi-cylindrical shape at the opposite ends of the converter, see above that the opposite semi-cylindrical parts have a cylindrical exhaust gas inlet 56 and form a cylindrical exhaust outlet 58.

As FIGS. 4 and 5 show, in the exhaust gas inlet 56 and the Exhaust outlet 58 sealed exhaust pipes 60 and 62 are used. With the preferred Embodiment is the exhaust gas inlet 56 slightly upwards and the exhaust gas outlet 58 offset slightly downwards to the longitudinal axis of the converter in order to reduce the To keep the gas flow as small as possible.

The offset between the exhaust inlet 56 and the exhaust outlet 58 can be can be chosen differently and depends on the location of the catalytic converter inside the exhaust system.

As shown in FIGS. 6, 11 and 12, the upper housing plate is 12 formed at both ends with a semi-cylindrical part 64, the concave surface of which is directed downwards, while the lower housing plate 14 at each end with same semi-cylindrical parts 66 is provided, the concave surface of which is upward is directed.

At the exhaust inlet 56, the upper container plate 26 and the lower Container plate 28 both provided with semi-cylindrical isobes 68 and 70, the concave Faces both face up and nested together with the upwardly directed concave surface 66 of the lower housing plate 14. At the exhaust outlet 58, the container plates 26 and 28 have semi-cylindrical parts 72 and 74, the concave surfaces of which are both directed downwards and together with the downward concave surface 64 of the upper housing plate 12 fit together. The cylindrical shape of the exhaust gas inlet 56 is thus made up of three layers of the semicylindrical one Parts 68, 70 and 66 of the plates 26, 28 and 14 are formed, the concave surfaces of which according to directed above and through the single semi-cylindrical portion 64 of the plate 12, the concave face of which is directed downwards, while the cylindrical shape of the exhaust outlet 58 through the three semi-cylindrical parts 64,72,74 of plates 12, 26 and 28, the concave surfaces of which are directed downwards, and the only ones opposite semi-cylindrical part 66 of the lower housing plate 14 is formed whose concave faces are directed upwards.

This configuration creates an inlet plenum within the housing 10 76 formed, which, as FIGS. 5, 6 and 7 show, with the exhaust gas inlet 56 in connection stand and to which the space 52 around the upper container plate 26 belongs. In the same Way, an off lasssammelkammer 78 is formed in the housing 10, which is connected to the exhaust gas outlet 58 stands in connection and to which the space 56 around the lower container plate 28 heard.

The catalytic converter thus contains an inclined catalyst bed, according to Pig. 6 runs inclined upwards from the exhaust gas inlet 56 to the exhaust gas outlet 58, so that exhaust gases entering the converter through exhaust gas inlet 56 are downward from the inlet plenum 76 through the reservoir plates 26 and 28 and through the catalytic material 48 pass through. The inclined catalyst bed has a relatively large volume with a relatively small thickness, so that a katalyitscher converter is formed, which has a relatively low overall height in proportion to its length, so that an effective treatment of the exhaust guaranteed and the catalytic converter is easily located in one place within the exhaust system can be attached to the vehicle, relatively close to the internal combustion engine, so that a quick warm-up of the catalytic converter is guaranteed compared to such which are arranged in the area of the usual silencer. The inclined catalyst bed and the downward flow of the exhaust gases ensure an even distribution of the flow of exhaust gases through the converter, causing dust formation and movement the particles of the catalytic converter are kept to a minimum. Although at In the preferred embodiment, the exhaust gases pass through in a downward flow the catalyst bed sloping from the inlet to the outlet could be passed the gas flow also takes place in the opposite direction, with the exhaust gases directed upwards flow through the catalyst bed sloping downward from the inlet to the outlet runs.

As shown in FIGS. 5 to 10, the housing plates 12 and 14 are with several press-in grooves 80 are formed, which press against the adjacent container walls 26 or 28 are present.

In this area there are openings 82 in the housing plates and are in alignment Breakthroughs 83 formed in the container parts through which supports 84 pass, which extends through the container 24 and the catalytic material 48 extend therethrough.

The supports 84 carry at their ends shoulders 86 on which the perforated walls 30 and 34 of the container plates 26 and 28 support. The breakthroughs 82 are surrounded by annular lips 88 which extend outward from the housing plates 12 and 14 extend. These lips 88 can be used in the formation of the openings in the plates are formed, so that a relatively loose fit of the supports 84 results. The lips 88 are secured with the supports 84 and reinforcement washers 90, which are inserted into the extrusions 80, welded and through a continuous annular weld 94 (Fig. 9) secured, which the individual parts together welded. The use of the supports 84 and reinforcement washers 90 increases the strength the housing and the container essential, so that a structure of high strength and Resistance to deformation at elevated temperatures and pressures achieved will. As the embodiment according to FIGS. 2 and 3 shows, with Breakthroughs provided parts 30 and 34 of the container plates 26 and 28 with reinforcing pins 96 are provided. However, it was found that the container sagged 24 at high temperatures and thus a throttling of the exhaust gas flow with omission the ribbing can be reduced if the Zabl der Slots 32 'according to FIG. 5 is increased.

The housing 10 has a cover 98 above the upper housing plate 12 provided, between which a layer 100 of heat insulating material, for example ceramic wool, is arranged around the catalytic converter against heat losses and shield the lower part of the vehicle from the heat of the converter. In the same way, a cover 99 can be provided next to the lower housing plate 14 be, in which a further layer 101 of heat insulating material between the lower housing plate 14 and the lower cover 99 is arranged to also at this side to prevent heat losses from the converter. The lids 98 and 99 are suitably connected to the housing 10 via U-shaped flanges 102 on the cover 98, which are bent around the edges of the flanges 20 and 22 of the housing 10, and thereby a flange 97 on the lower cover 99. The upper cover 98 can be used to increase the Rigidity be provided with ribs 103.

In the manufacture and assembly of the described catalytic .onverters, the housing plates 12 and 14 are essentially the same pressed pieces, in the manufacture of these, the Eimpressungen 80 and the openings 82 in a single one Operation are formed. As the two panels essentially are the same, they can be made with the same tools, whereby the Economy and stock keeping are simplified. In the same way the container plates 26 and 28 are produced with the same tools, so that the plates are interchangeable.

If desired, one of the housing plates can be used prior to assembly and the adjacent container plate and one of the lids with holes 104, 105 and 107 are provided in the side walls (Fig. 12), through which a test device after The assembly can be introduced to the temperature of the catalyst bed or to check its effectiveness. In the preferred embodiment of the invention this is the only difference between the otherwise equally trained couples of plates.

The four plates 12,14 and 26,28 are then together with the supports 84 assembled and placed in an assembly device in which the circumferential flanges 20, 22, 42 and 44 to be planted in the four-layer arrangement, whereupon by a single, essentially continuous, circumferential weld seam 50 (Fig. 11) the inner and outer AB seal is made.

The welding is conveniently done automatically, including the plates be rotated in the holder and the edges on other circumference in the area of a arranged vertically Electron beam welding machine in motion through which a substantially continuous weld seam is formed.

The reinforcement washers 90 are then applied and with the supports 84 and the lips 88 connected by a continuous weld seam 94, for which purpose likewise an electron beam welding machine is preferable.

The exhaust pipes 60 and 62 are then inserted into the exhaust inlet 56 and the exhaust gas outlet 58 is inserted and through a continuous circumferential weld seam 106 (Fig. 4) attached.

Finally, the catalytic material becomes 48.

into the space 46 of the container 24 through a filling hole 108 (Fig. 6 and 12) into which a threaded bushing 109 is welded. The catalytic one The converter is suitably shaken while it is being filled with the catalytic material, in order to achieve a tight packing of the catalytic material. It then becomes a Sealing plug 110 screwed into sleeve 109. The arrangement of the filling opening at the bottom of the converter enables the replacement of the catalytic material at am Vehicle mounted converter.

The insulation layers 100 and 101 are then above and below of the housing 10 held in place by the covers 98 and 99, what the peripheral flange 102 is bent around the peripheral edge in the area of the weld seam 50 and the flange 97 of the lower cover 99 is bent.

The use of essentially identical parts and the way in which they are connected results in a sealed structure @ that is easy and inexpensive to manufacture and assemble is.

During operation, the engine exhaust gases come out of the Exhaust pipe 60 through the exhaust gas inlet 56 and around the exhaust gas inlet plenum 76 the upper plate 26 of the container 24 and then flow through the openings 32 in the upper part 30 of the container 24. They then pass through the catalytic material 48, in which the oxidation and / or reduction takes place. The treated gases enter through the openings 36 in the wall part 34 of the lower container plate 28 and are collected in the outlet plenum 78 to then pass through the exhaust outlet 58 and the exhaust pipe 62 to exit the open air via an exhaust pipe of the exhaust system.

At the increased operating temperatures of the converter, which can be up to 880 0C, the material from which the converter is made is necessarily deformable at a lower load than at normal temperature. Therefore, the housing and the container tend to be under the action of gas pressure in the booverter, which results from the restricted flow through the catalyst bed results in bending outwards. The design according to the invention avoids this Problem with the arrangement of the impressions 80 in the case 10, which bear against the container 24, and which extend through the container extending supports 84 connected to housing panels 12 and 14. These Supports maintain a predetermined distance between the container plates and cause the housing plates to rest against the container plates, so that a rigid structure is created, the container 24 an increased resistance against deformation gives. In addition, the attachment of the supports results in Housing by means of the reinforcement washers places in the housing panels, which are in the outward direction are relatively immobile and thus represent a reinforcement that the the stress required to deform the housing is significantly increased.

The catalytic reaction that takes place in the catalyst bed is exothermic, so the temperature of the catalyst bed and the treated Exhaust gases are increased as these heated exhaust gases in the outlet plenum 78 cover the bottom plate 28 of the container 24, the temperature of the catalyst bed is maintained and even out the temperature around the converter housing, creating heat tensions are reduced.

Typical catalysts used in catalytic converters for internal combustion engine exhaust can be used generally only effective if they have a Temperature of about 120 0q have assumed, so that a time lag between the exit of the exhaust gases from the internal combustion engine when starting up to the beginning the catalytic conversion of the exhaust gases occurs, which occurs through the necessary AuShiizen the catalytic material is determined by the exhaust gases. Since, as already mentioned, the construction according to the invention maintaining the temperature of the catalyst bed supports and the exiting exhaust gases through the heating of the incoming exhaust gases Contribute heat conduction via the flanges 42 and 44 of the container 24, results an early heating of the catalytic material to the required operating temperature, whereby the operation of the catalytic converter is weakened.

The embodiment of FIGS. 1 to 3 is similar to the preferred one Embodiment according to FIGS. 4 to 12, but there are the upper and lower ones Lid for holding a heat insulating layer omitted and in the container plates Reinforcing ribs 96 are formed.

Claims (11)

Patent claims: (g) Eatalytic converter for internal combustion engine exhaust gases, in which the exhaust gases are fed to an inlet chamber in a housing and through a Catalyst bed held in a container in the housing step before never coming out of a Outlet chamber exit the housing, this is not shown t that an elongated housing (10) arched by two opposite one another upper and lower plates (12,14) is formed and at a distance the container (24) Surrounded for the catalytic converter, which consists of two opposing domed Plates (26 and 28) are formed which extend over substantially the circumference extending flanges (42,44) abut against each other, which between similar grip substantially circumferentially extending flanges (20, 22) of the housing, the four plates being sealed against one another at their peripheral edges (50), and that the plates at their opposite ends have parts (64; 66; 68,70; 72,74) have, which at one end has an exhaust gas inlet (56) to a collecting chamber g76) between the one housing plate (12) and the adjacent container plate (26) and at the other end an exhaust gas outlet (58) from a collection chamber (78) between the other plates (14 or 28) of the housing or of the container, the last plate with openings (36) is provided that hold back the catalytic material (48), but the passage allow the exhaust gases. 2. Catalytic converter according to claim 1, characterized in that that the parts (64; 66; 68,72; 70,74) at the ends of the plates are essentially semi-cylindrical Half of the shape, the part (64) on the upper housing plate (12) with the concave surface directed downwards, the part (66) on the lower housing plate with the concave Face facing upwards and the parts (72,74) at one end of the container plates (26,28) with the concave surface pointing downwards and the parts (68,70) on their other ends with the concave plate facing upwards, the three being the same directed portions (68,70,66; 74,72,64) of the plates at each end of the converter with the opposite part (64,66) of the vderten plate (12 or 14) the exhaust gas inlet (56) or the exhaust gas outlet (58) with an essentially cylindrical shape. 3. Catalytic converter according to claim 1 or 2, characterized in that that the container (24) for the catalyst has essentially the same height and is inclined to the longitudinal direction of the housing (10). 4. Catalytic converter according to claim 3, characterized in that that the curved parts of the upper and lower container plates (26,28) from the Inlet side to outlet side of the converter increase in height bs decrease. 5. Catalytic converter according to one of claims 1 to 4, characterized characterized in that supports (84) are substantially perpendicular between the container panels (269, 28) are arranged and hold them at a predetermined distance from one another and are fixed at their ends to the housing plates (12, 14). 6. Catalytic converter according to claim 5, characterized in that the supports (84) with their end through aligned openings (82,83) in the Container plates (26,28) and the housing plates (12 and 14) join and with the housing plates are welded. 7. Catalytic converter according to claim 6, characterized in that that the supports (84) are provided with shoulders (86) against which the inner surfaces of the container plates (26, 28) and the openings in the housing plates outwardly directed lips (88) are formed with the ends of the supports attached reinforcing washers (90) through a continuous weld seam (94) are connected. 8. Katalyttscher converter according to claim 7, characterized in that that the openings (82) for receiving the supports (84) ia impressions (80) of the Housing plates (12,14) lie against the adjacent container plates (26,28) issue. 9. Catalytic converter according to one of claims 1 to 8, characterized characterized in that the openings in the container plates (26,28) through from these Arched pressed parts (32 ') are formed. 10. Catalytic converter according to one of claims 1 to 9, characterized characterized in that an upper cover (98) is located above the upper housing plate (12) with a peripheral flange (102) is provided over the sealed peripheral edges (50) of the housing and container panels is bent and between the top lid and a layer (100) of heat insulating material on the upper housing plate is provided. 11. Catalytic converter according to claim 10, characterized in that that a cover (99) is attached below the lower housing plate (14) and between this and the lower housing plate a layer (101) of heat-insulating Material is provided.