FR2619413A1 - CATALYTIC CONVERTER SUBSTRATE SUPPORT FOR MOTOR VEHICLES; CONVERTER THUS OBTAINED, AND METHOD OF MANUFACTURING THE SAME - Google Patents

Abstract

A catalytic converter of the automotive type comprises a substrate 7 with a reduced central section 29 which compresses a support mat 13 around the substrate, the ends of the body 3 of the converter being spherical for attachment to spherical flanges 25, 27 on bushings. end 17, 19 or being in one piece with the body. The method of manufacturing the converter substrate and the converter itself is also described.

Description

The present invention relates to catalytic converters for

  engine exhaust systems & internal combustion, and more particularly, catalytic converters intended to be installed in motor vehicles as first equipment by the manufacturer as a replacement or for workshops specialized in the transformation of the first equipment. The object of the present invention is to reduce the dimensions and the number of parts of a catalytic converter <in relation to known practical constructions), while at the same time increasing its efficiency.

  and improving its construction and manufacture.

  The invention achieves the foregoing object by means of a substrate support in the form of a reduced diameter converter tubular body and a central portion so as to compress a support mat around a catalyst substrate. In one embodiment, the ends of the body have a spherical radius so as to produce a substrate substrate of the converter that can

2619 4 13

  be shipped "as is" or assembled to form a converter. This type of converter is completed by fixing input and output sockets to the ends of the substrate support and this can be done in the factory or at a certain stage downstream. In another embodiment, the body is made of two halves, a sleeve being formed in each of them. One of the halves has a reduced diameter so as to support the substrate, and the other is compressed on the first and is there

fixed.

  The present invention is translated by a converter of a fairly short length, with few parts, having a maximum efficiency because 100% of the end faces of the substrate can be used, and better

substrate support accuracy.

  The present invention will be well understood on reading

  of the following description made in relation to the

  drawings in which: Figure 1 is a longitudinal sectional view along the axis of a preferred embodiment of converter according to the invention; Figure 2 is a longitudinal sectional view of a half of another embodiment of the invention, showing the mattress and the substrate after padding; Figure 3 is a sectional view similar to that of Figure 2, but showing the parts after diameter reduction; and Figure 4 is a longitudinal sectional view of the

  completed converter of Figures 2 and 3.

  In connection with FIG. 1, a catalytic converter 1 according to the present invention, intended to be used in the exhaust system of motor vehicles, comprises a metal body made of sheet metal 3, preferably round and symmetrical, tubular, with an open end, the interior of which defines a chamber 5 for a round, symmetrical ceramic honeycomb-type catalyst substrate 7 (found on the market) having flat ends 9 and a large number of longitudinal passages 11 coated with a honeycomb cell catalyst extending between one end 9 and the other end. The central portion of the substrate 7 <less than the total length) is surrounded by an elastic, insulative, resilient, annular support pad 13 which is preferably made of a gas impermeable vermiculite material (which found on the market) which expands substantially on heating. This preferably has a thickness of about 6 mm and is compressed radially during assembly on about half of its initial thickness. The opposite end portions 15 of the body 3 are preferably stamped or shaped so as to have a partially spherical shape as illustrated, having central openings of a diameter substantially smaller than that of the substrate 7. End sleeves 17 and 19 for the passage of gases have tubular outer ends 21 and 23, respectively, for attachment by welding or clamping, or otherwise, to the pipes of the exhaust system (not shown). They also include spherical, partially annular, outwardly flared flanges 25 and 27, respectively, each preferably being formed on a radius corresponding to that of the body portions to which they are welded at selected locations so that their ends 21 and 23 have the desired orientation relative to the axis of the body 3. The end 21 is shown as oblique and the end 23 as being coaxial, but account is taken of any other angular arrangement by the surfaces

spherical coupling.

  The body 3 is preferably made of a metal tube section having a uniform diameter and thickness. The substrate 7 is, with the annular band 13 of the mattress located at its center, placed in the center of the chamber and has the same axis as the tube, the diameter of which is then reduced uniformly by a known suitable means (for example, see FIG. U.S. Patent 3,382,948, Figs. 2 and 2A) to provide a central ring portion 29 of reduced diameter having the same length as the mattress 13, whereby the radially uniform compression of the mat around the outside of the substrate over about half of its original thickness or in the free state, which makes it possible to firmly but somewhat resiliently support the substrate in the central position. The ring portion 29 maintains the radial compression of the mattress 13 and both apply radial pressure sufficient for holding in the central position and serve as the only means of impact-resistant mounting and support of the ceramic monolith. The body 3 has intermediate portions 31 of substantially uniform diameters which extend between the opposite ends or outer ends of the central portion 29 and the inner ends of the spherical ends 15, the spherical ends 15 being formed in the metal body 3 after the own formation of the ring 29 so as to hold the substrate in place. The parts 31 are spaced radially outwardly of the substrate 7 and preferably extend to near the ends 9 of the substrate, where the curvature begins to give the

spherical ends 15.

  Where appropriate, sockets such as 17 and 19 may, after formation of the ends 15, be welded in place at the factory. Alternatively, the converter substrate, or body 3 with the substrate 7 and the formed ends 15, may be sent downstream of the vehicle manufacturer, to the warehouses, repair shops, etc., where the bushings may be attached.

  to satisfy a specific application.

  From the point of view of the manufacturing method of the converter 1, the body 3 preferably has the origin in the form of a simple metal tube of uniform diameter, open at both ends. The mattress 13 is placed around the median section of the substrate 7 and this set is

  inserted into the tube in such a way as to be

  nally and radially in it. While maintaining this centering relation, the wall of the tube is compressed radially to give the section 29 with reduced diameter ring which, thanks to its radial contact with the mattress 13, compresses it radially and applies a radial pressure to the substrate 7. radial deformation of the ring 29 is sufficient to apply to the mattress and the substrate sufficient radial pressure and maintain it and allow absorption of shock by the mattress while maintaining the substrate centered in the tube so that its end angles do not not come into contact with the surface of the inner wall of the tube. After forming the ring 29 so as to hold the substrate 7 in place, a radial pressure is applied to the ends of the tube so as to deform them inwards and obtain the spherical ends 15 while maintaining the substantially cylindrical sections 31 in order to preserve the clearance between them and the substrate 7. This completes the substrate of the converter and the converter is completed by welding the sleeves 17 and 19 on the ends 15. Alternatively, one of the spherical ends 15 could be formed in the front body inserting the substrate into the other end

  and held in place by the formation of the ring 29.

  In use, the converter 1 will normally be attached to the exhaust system by welding or other means for attaching the parts 21 and 23 to the exhaust system ducts. Either end may be the inlet port. The exhaust gas passes through the longitudinal passages 11 which are coated with catalyst so as to reduce the nitrogen oxides and to oxidize the hydrocarbons and the carbon monoxide in order to obtain acceptable levels of emissions. If a vermiculite-based mattress 13 is used, the heat due to the reaction during the initial operation of the converter

  will cause it to dilate, hence the improvement of

  the reliability of the connection between the substrate 7 and the body 3 simultaneously with the relatively high friction resistance which makes it possible to prevent the substrate from sliding relative to the body 3. For after-sales service, the substrate 7 will be selected, dimensioned, and processed with the catalyst to produce emission levels

  acceptable for a wide range of different engines.

  By way of example of the approximate dimensions for automotive applications, the substrate 7 may have an outside diameter of about 10 cm and a length of about 12 cm, and be evenly spaced about 1.5 mm from the inside surface of the ring 29 and about 0.10 mm from the inner surface of the intermediate portions 31, and the horstout length of the body 3 after formation of the spherical ends may be 1819 cm. This is a length substantially less than that required to support the substrate in a conventional manner in a body of similar shape by means of L-shaped support rings. In addition, 100% of the end faces 9 and longitudinal passages 11 of the substrate can be used for conversion, hence increasing the efficiency of the converter. Another comparison with the method of support with L-shaped rings shows that the number of parts of the converter 1 is reduced to only 5 and that the method of supporting the substrate by uniform radial compression applied through the ring 29 makes it possible to obtain greater precision in the manufacture, hence reducing the risk of rejects. The spherical ends 15 and the sockets 17 and 19 constitute a "universality" feature which favors the reduction of stocks, a better service and lower costs. The body 3, without the sockets 17 and 19, comprises a substrate support that can be shipped with a reduced risk of shock damage to the brittle ceramic substrate due to the protection provided by the spherical ends and by the unique method of mounting the substrate that provides a vast

play for the angles of it.

  In connection with FIGS. 2-4, the present invention is illustrated as a converter 101 (FIG. 4) having an elongated round tubular body 103 which contains a catalyst substrate 107 (preferably the same as the substrate 7). with flat ends 109 and longitudinal passages 111 for gas in honeycomb cells, between one end of the face 109 and the other end. The central portion of the substrate 107 is surrounded by a support mattress 113 which is preferably identical to the mattress 13. End sleeves 115 and 117 for the gas stream are preferably in one piece and formed by stamping or deformation of a metal in the ends, respectively, of the body halves 119 and 121 which interlock together to form the body 103. The halves 119 and 121 may be formed or stamped and drawn from round cylindrical tubes which have inner ends 123 and 125, respectively, of uniform diameter and wall thickness. The outer portions 127 of the halves are formed into segments that melt into the sockets and 117. The segments 127 are illustrated as constituting the spherical bushing 115 of the same axis as the body 103, and the sleeve 117 inclined with respect to the axis

of this body.

  As seen in FIG. 2, the substrate 107 and its central mattress 113, placed symmetrically, have an outside diameter which is approximately the same as the inside diameter of the end 123 of the half-body 119, where it As a result, the combined substrate and mattress can be introduced into the open end ll9a of half 119 and placed with the outer end of the mattress substantially in the same plane as the end 119a (a set being preferably provided for expansion). longitudinal of the mattress due to radial compression). As can be seen in FIGS. 3 and 4, the end of the portion 123 has a reduced diameter along the section 129 at approximately the wall thickness of the halves 119 and 121, or about 50% of the wall thickness. origin of the mattress 113. The reduced diameter section 129 has a length

  virtually identical to that of the compressed mattress.

  As can be seen in Figure 4, the open end 121a of the half 121 snaps onto the reduced diameter section 129 of the half 119 so that the end portion 125 slides on the section 129 over the desired length. overlap, the overlap illustrated in Figure 4 being the length of the mattress 113 and section 129 whose overlap may be lower. Then, end 125 and half 121 may be attached to end 123 and half 119 as shown.

by the annular weld 131.

  With regard to the method of manufacturing the converter 101, the two halves 119 and 121 are preferably in the form of simple metal tubes of uniform diameter and open at both ends. The end of each of the halves is deformed by appropriate drawing or stamping operations, etc., so as to form the sections 127 and the sockets and 117 with the desired orientation relative to the axis of the tube. The mattress 113 is wrapped around the substrate, preferably symmetrically with respect to the ends as illustrated, and this assembly is inserted into one of the halves (eg half 119) so that the rear end of the mattress is approximately in the same plane as the end of the half (for example the end 119a). Then, the wall of the half containing the substrate is compressed radially in the ring 129, the deformation along a radius preferably being substantially the thickness of the wall of the metal tube at

  from which the halves 119 and 121 are formed.

  The assembly is then completed by sliding or fitting the second half (for example the half 121) on the ring 129 (which now has an outer diameter substantially identical to the inner diameter of the second half) according to the desired amount for the overlap and by welding or other method of attachment to the two halves. If the two bushes 115 and 117 are oblique with respect to the axis of the converter 101, the second half will also be positioned angularly in the location

  desired before welding in the first half.

  While halves 119 and 121 are shown with one-piece end sleeves 115 and 117, sockets 115 and 117 could be omitted (so that body 103 would be a substrate holder) and gas bushings would be omitted. could be patches as illustrated at 17 and 19 for the converter 1 of Figure 1, in which case it would be important for the ends of the halves to be spherical as illustrated in 127. Another alternative would be to have the spherical ends 127 without any opening (with the exception of an air vent for assembly purposes, if applicable), where

  the result would be that the installer of the converter

  pierces openings for the passage of gases to the positions

  desired and would weld sockets of the hat type of

  As shown in Figure 1, this variant provides maximum protection against substrate damage during shipping and storage. The basic idea of the open and closed spherical ends for a conventional converter is described and claimed in the pending U.S. patent application

846 058 series.

  To obtain the best results, it is important for the converters 1 and 101 to choose the appropriate length for the mattress 13 or 113. If the mattress is too long, the fibers may break or be released by the pulsations of the gas and enter the longitudinal passages 11 or 111 and close them. In addition, if the mattress is too long, a phenomenon can occur in which temperature gradients develop on the substrate that can place it in tension, resulting in cracking of the center. On the other hand, if the mattress is too short, the substrate can swing or resonate causing damage if it hits the metal body 3 or 103. To reduce the above risks, it is desirable that the length of the mattress is equal 50% to that of the substrate, preferably about 60%. At these lengths, a special advantage is obtained in that it is believed that static conditions develop in the space between the outer diameter of the opposite ends of the substrate and the walls of the bodies 3 and 103, where the gas is relatively stagnant. . This is thought to protect the ends of the mattress and tends to reduce the risk of fiber separation and entry into the substrate. The present invention is not limited to the embodiments which have just been described; on the contrary, it is capable of variations and modifications which will be apparent to those skilled in the art. For example, while spherical ends 15 are preferred for converter 1, the same advantages will be obtained if conventional conical bushings are attached to sections 31 instead.

  sockets 17 and 19 shown.

t

Claims (29)

  Substrate support for a catalytic converter of the type used in the exhaust systems of motor vehicles, characterized in that it comprises an elongate tubular body, a catalyst substrate inside the body, a support mattress surrounding a central portion of the substrate, the body having a central portion of reduced diameter, radially compressed against the mattress and the substrate so as to maintain the latter in position in the body.   Substrate holder according to Claim 1,   characterized in that the mattress is made of a material which expands substantially by heating and therefore increases the radial compression between the substrate and the part with reduced diameter.   A substrate holder according to Claim 1, characterized in that the body has cylindrical portions extending longitudinally away from opposite sides of the reduced diameter portions and radially spaced from the outer surface of the substrate in a   quantity substantially greater than the thickness of the mattress.   Substrate holder according to Claim 3, characterized in that the mattress and the central part have substantially the same length.   Substrate holder according to Claim 1, characterized in that the mattress consists of a fibrous material and its length is approximately 50-90% of that of the substrate.   Substrate holder according to Claim 1, characterized in that the body is open at the ends and has end portions for fixing and fixing.   end sleeves for the passage of gases.   Substrate holder according to claim 6, in which   which end portions are in the form of a sphere.   Substrate holder according to Claim 1,   characterized in that the body is closed at the ends.   Substrate holder according to Claim 8, characterized in that the body has end portions of spherical shape.   Substrate holder according to claim 1, characterized in that the body is made of one piece and   the central part is formed in this room.   Substrate holder according to Claim 1, characterized in that the body comprises two nested sections one inside the other and the reduced diameter central portion is formed in one end of one of the sections and the other section mounts on the central part with reduced diameter.   12. Catalytic converter of the type used in the exhaust systems of motor vehicles, characterized in that it comprises an elongated tubular body and open at each end, a catalyst substrate inside the body, an elastic mattress of support around the central portion of the substrate, the body having a central portion i reduced diameter, radially compressed against the mattress and the substrate and serving as support means for the substrate, and sockets for the passage of gases at the ends opposite of the body.   Converter according to Claim 12, characterized   in that the end portions of the body have the shape of a sphere and the end sockets have flanges of   spherical shape that are attached to the spherical ends.   Converter according to Claim 12, characterized   in that the body is made of a workpiece and the central portion of reduced diameter is formed in this piece.   Converter according to Claim 12, characterized   in that the body contains two sections nested one inside the other and the central portion of reduced diameter is formed in the end of one of the sections and the other   section mounts on the central part with reduced diameter.   Converter according to Claim 12, characterized   in that the mattress and the central diameter portion   reduced serve only means of support for the substrate.   Converter according to Claim 16, characterized   in that the mattress and the central portion & reduced diameter have substantially the same length and length   is equal to about 50-90% of the length of the substrate.   18. Converter according to Claim 17, characterized   rised in that the length is about 60% of that of the substrate.   19. Converter according to Claim 12, characterized   in that at least one of the end sleeves for   the passage of the gases is oblique with respect to the axis of the body.   20. Converter according to Claim 12, characterized   in that the mattress is made of a heat-expandable fibrous material and has a length substantially equal to about 50-90% of the length of the substrate, the mat being compressed by the reduced-diameter central portion to 'about half of his thickness in the free state.   21. Converter according to Claim 20, characterized   characterized in that the body has cylindrical walls spaced radially from the ends of the substrate projecting beyond the mattress a distance substantially equal to that of the projecting ends of the substrate, the radial spacing being substantially the same as the thickness mattress in the free state.   22. Converter according to Claim 21, characterized   in that the body has ends extending outwardly from the outer ends of the walls   cylindrical and the ends are spherical.   23. Converter according to Claim 22, characterized   in that the ends start in planes substantially coinciding with the end faces of the substrate. 61913   24. A method of manufacturing a converter substrate for use in a catalytic converter of the motor vehicle type, characterized in that it comprises the steps of: placing an annular support mat shock absorbing around the intermediate section only a catalyst substrate, inserting the assembled substrate into the hollow metal body, radially deforming the wall of the metal body to obtain a reduced diameter annular ring in annular contact with the annular mattress to apply radial pressure and maintain it and radially compressing the mattress to substantially reduce its thickness and apply sufficient radial pressure against the substrate   in order to keep this one in the body.   25. The method of claim 10, characterized in that it comprises the further step of applying radial pressure to an outer end of the body so as to deform radially inwardly.   to obtain an extreme part of predetermined shape.   Process according to claim 24, characterized in that the assembled substrate is inserted into the body so as to be centered longitudinally and axially therein and in that the central portion of the wall of the   body is deformed to give annulaie ring.   Method according to claim 24, characterized in that the assembled substrate is inserted into the body so that it is axially centered therein, but an end beyond the mattress extends out of the body and in that that one end of the body wall is deformed to provide the annular ring, and further comprising the steps of engaging a second hollow metal body on the annular ring and securing the second body to the first body in the nested state.   28. A method of manufacturing a catalytic converter of the automotive type, characterized in that it comprises the steps of deforming a first end of a tubular metal body of uniform diameter to obtain an end sleeve for the passage of gas, deforming a first end of a second tubular metal body of uniform diameter to obtain an end sleeve for the passage of gases, to place a shock absorbing annular mat around a median section only of a substrate of catalyst, to insert the assembled substrate in the first end of the first body so that the outer end of the mat is radially aligned with the end of the first body, to radially deform the wall to the right of the first end of the first body to obtain an annular ring of reduced diameter in radial contact with the annular mattress in order to apply and maintain the radial pressure and radially compressing the mattress in order to substantially reduce its thickness and to apply a sufficient radial pressure against the substrate to maintain it in the first body, and to fit the first end of the second body on the ring and fix together the first and second halves.   29. The method of claim 28, characterized in that it comprises the step of deforming the wall of the first end of the first body over a radial distance substantially identical to the wall thickness of the   first end of the second body.