DE2403973A1 - CATALYST UNIT - Google Patents

Description

.PA TK] VT TO WS. (.TB

dr. ing. H. NEGENDANK · bipiwng. H.HA1JCÄ Dipl.-Phys. W. SCHMITZ

. E. GRAALFS dipping. W. WEHNERT O / fl O η 7

HAMBURG-MUNICH £ H U O CJ / O ZTTSTEIXTTNGS ADDRESS: HAMBTTRQ 36 · NEHER WAI! 41

TEL ·. Se 74 88 UNS 3β 4110

IEIEGB. IfSQBDAPATENT HAJIBtTHG MUNICH 15 MOZARTSTR. 23

TEL ·. 0 38 09 pp

TElEGR. NEQESAFATENT MUNICH

Hamburg, January 28th

TENNECO INC.

1201 Michigan Boulevard, Racin. Wisconsin 53402 / USA

iL 'catalyst unit

The Jäirfinching concerns a catalyst unit, which in an exhaust system of an "internal combustion engine" is arranged.

The object on which the invention is based exists therein, the efficiency of a monolithic catalytic converter element (as shown in Uö-Pü 3 441 381) increase and extend the service life.

This object is achieved according to the invention by that the outward or outlet end face of the element a

Shape is given which essentially corresponds to the velocity profile of the gas over a diametrical section of the gas line is equivalent to.

Several embodiments of the subject matter of the invention are to be described below in connection with the drawings, ü's show:

i? ig. 1 a partially broken off and partially cut schematic side view of a motor vehicle exhaust system with a liatalysatorein-unit according to the invention;

ij'ig. 2 a broken longitudinal section of a line, in which a typical gas velocity profile is shown iatj

j? y. 3 is an enlarged broken section of FIG .Catalyst unit according to j? 1;

jfig. 4 one of the i'ig. 3 similar section, but one altered embodiment j

irig. 5 shows a cross section along line 5-5 of the Jttlg, 3? and

fig. 6 is a side view of a further modified .Catalyst element.

His combustion engine 1 has an exhaust manifold 3, the gas discharges through its outlet 5 into the inlet of an exhaust pipe 7 of an exhaust system 9, the

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a catalyst unit 11 contains. The unit 11 discharges the gas into a line 13 which can feed it to another device in the system or release it into the atmosphere. The plant shown is used specifically in a motor vehicle exhaust, but can also be used in conjunction nit catalyst units for various other exhaust systems of internal combustion engines.

The catalytic converter unit, 11 has a tubular shape. outer housing 15, which is located between a jiinlaßkonus 17 and an outlet cone 19, which with lines 7 or 13 are connected, ϋη cylindrical, monolithic, honeycomb-shaped catalyst "element 21 is by means of a flexible Necks 23 are supported coaxially in housing 15 and have an outlet face 25 which receives gas from line 7 and an outlet face that carries the gas into the conduit 13 unsubscribes.

The element 21 is general in the relevant engineering known and consists of a rather fragile, monolithic, honeycomb-shaped, heat-resistant material with elongated cells, channels or passages extending from the jjiin to the outlet face of the body

stretch. Catalyst material is on the walls of the passageways applied, which promotes the conversion of undesirable constituents in the exhaust gas flowing through the element. Heat is in the clement in a larger or smaller Measure freely, depending on the converted constituents, but with the temperature along the central axis of the

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jülementes several hundred degrees higher than that of the unit 11 ambient temperature is. u the temperature of each channel

29 iot a jjiinktion e'er c.urcb the same amount of flowing gas,

30 that a non-uniform ötrcmungsverteilung different expansions promote the element, resulting in iträfteentudcklungen that üisse of the fragile, ^ itzebeständigen Matriais and an "expiration of the same cause. V / ie in the Geachwincligkeitsprofil 31 of the jj ^T ig. 2, the gas flow is Pieter ^ a round pipe never ^ t uniformly, the maximum velocity occurring in the middle of the pipe and the minimum velocity along the slope, this difference in velocity increasing with the velocity of the flow, the curve of the gas flow tending to promote the breakdown of the fragile element 21.

It was found that a catalyst system using a monolithic element, such as element 21 _: for example, is highly effective when the gas flow rate is uniform, i.e. v / enn. Let all parts of the element pass the same volume of gas Oe time unit. Normally the jin- and outlet end faces 25 and 27 are flat, parallel and perpendicular to the axis of the element 21. When considering the jj-shape of the ashiness profile 31 it becomes evident that the natural, not even flow distribution is low Effect graph of the catalytic converter operation to the sequence

These ranks namely the low degree of delineation and the inclination the invention counteracts decay,

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in that one or both end faces 25 and 27 are given a convex contour in order to achieve a more uniform residence time of the gas in the passages 29. The convex contour, namely a cotation surface around the axis of the unit, provides longer passages in the j & it "ce of the element, where the gas velocity is greatest, and shorter passages in the outer sections where the gas velocity is a minimum. The changes Conversely, the lengths coincide as closely as possible with the changes in speed over the diameter of the element, and the non-uniformity of the profile 31 is directly related to the flow volume, and since flow speeds in motor vehicles vary greatly, the contours for a certain vehicle speed are normal selected in the order of 4Ό to 56 km per hour, in which a maximum catalyst efficiency is highly desirable.

According to these findings, the inlet end face 25 of the Jülementes 21 is convex essentially inversely to the speed spr of il 31, so that an essentially uniform head speed is achieved through the Clement at speeds for which the profile 31 is calculated. j? y. 4 shows the reverse arrangement, in which the out let s * tirnf lug 27 of the modified element 21 ^f having a convex contour which corresponds to the ij'orm another, flatter velocity profile is generated at a lower speed substantially. Obviously, both end faces can have a convex contour in order to create the desired, differently long passages 29 "

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to achieve, as it is shown at the 3tirnflä.chen 25 "and 27" of the islemente.3 21 "in Jj ¹ Ig. 6.

The convex inlet face 2> the irig. 3 is currently desired for another reason, it is part of the inflowing Gas in front and is completely surrounded by gas, in contrast to the downstream portion where the outer surface is surrounded by the insulating, resilient sleeve 23 is. uie ilache therefore has one when the machine is started I don't want the ignition temperature of the catalytic converter a little faster than is the case with the usual flat inlet end face 2y the jrig. 4 which is jcall.

It can thus be seen that the invention provides means to improve the performance of a monolithic catalyst element and to reduce the deleterious effects of differential expansion by contouring one or both faces of the element which allows for more uniform gas flow and residence time provides over the cross section of the element.

Changes to the special training courses and arrangements can without deviating from the idea of the invention.

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Claims (9)

Claim e 1. Jiatalysatoreinheit which is arranged in an exhaust system of an internal combustion engine, characterized in that a ro ^ r-shaped housing (.15) is provided with a longitudinal axis and an inlet (17) stm one longitudinal end and an outlet (19) at the other longitudinal end, in which a monolithic, honeycomb-shaped catalyst element (21; 21 ^f 21 ^M ) is supported, which has elongated passages through which exhaust gases flow from the outlet to the outlet, so that the catalyst element has an inlet end face (25; 25 ') and an outlet end face 27 ; 2? ^f ) in which the passages open, and that the end faces have a shape, by means of which passages of unequal length arise, of which the longest near the horizontal acJi se and the shortest near the outer circumference of the catalyst at ore lement it away from the longitudinal axis are arranged. 2. üatalyst unit according to claim 1, characterized in that that at least one of the end faces (25,27) transversely aur longitudinal axis is convex. 3. üatalyst unit according to claim 1, characterized in that that the end face (25) at the niinlaßeade of the catalyst element it (21) is convex transversely to the longitudinal axis. 4. üatalysatoreinheit nac ^ claim 1, characterized in that the 3tirnflache (2? ^F ) on Auslaßenöe of the catalyst element it (21 ') transversely to the longitudinal axis convex forms is. 409835/0676 «= ■ 3 - 5. catalyst unit nac >> Claim 1, characterized in that both end faces (25, 27) are transverse to the longitudinal axis convex 6. catalyst unit according to claim 2, characterized in that that at least one of the 3 end faces (25) one is a convex surface of revolution about the longitudinal axis. 7.) iiatalyst unit according to claim 1, characterized in that that the ü'orm. one of the end faces (25) the speed profile (31) Cies to the beginning of flowing gas is equivalent to. S. exhaust system of an internal combustion engine, thereby characterized in that a catalyst unit in the system (9) (11) arranged and via a line (7) to the machine (1) is connected, with the gas flowing through the line having a characteristic velocity profile (31) has that the catalyst unit has a longitudinal axis and a monolithic, honeycomb-shaped body (21) with one inlet and one outlet face (25f25 'or 27.27') is that the body (21) is located between the inlet and outlet end faces continuously extending, catalyst-carrying, the gas-conducting longitudinal channels (29), and that one of the ytirnflachen (25) a corresponding to the velocity profile has convex contour. 9. Catalyst unit according to claim 1, characterized in that that the length of the passages (29) through the 409835/0676 Velocity profile (31) of the to the catalytic converter element flowing gas is determined, and that the residence time of the gas in the passages is essentially the same in all passages " 409835/0676 Blank page