AU600007B2

AU600007B2 - Catalytic converter and substrate support

Info

Publication number: AU600007B2
Application number: AU76607/87A
Authority: AU
Inventors: Leonard Jay Dryer; Thomas Joseph Schwarte
Original assignee: Tennessee Gas Pipeline Co LLC
Current assignee: Tenneco Automotive Inc
Priority date: 1987-07-31
Filing date: 1987-08-04
Publication date: 1990-08-02
Anticipated expiration: 2007-08-04
Also published as: GB2207615B; FR2619413B1; GB8718166D0; JPS6460711A; GB2207615A; AU7660787A; DE3727217A1; FR2619413A1

Description

-6-00007 COMMONWEALTH~ OF AUSTRALIA PATENTS ACT 0Y62 COMPLETE SPECIFICA"TION

(ORIGINAL,

FOR OFFICE, USE Application Number: Class Lodged: ro~m i0 In~t. Clas Complete Specification-Lodged: Accepted: Published: Priority: Related Art: i J ~S cor:*Cet for r, TO BE COMPLETED BY APPLICANT Name of Applicant: £EN*CO INC., Cor,,or'ation r7iriiPsed iin theo lavs Off the State of D~elawtire, Addirese of Applicant; Tenrieya Automotive Builiyr hn 1 sujite 10() Tri State Trite miati orid Lincolrishlte, Illinois United St,,toe' of Awrimi.

Actual Inventor: VV0A1~) JY I)iRYF1R xd THO[- AS J oSIP E[4 1\ AICTI Addtess for Service: Wray Assooiatv, l)rimarvy lndttry Ilotise, 239 Adelaide rert ~e Perth, W.A. 6000 Complete Sp-cification tot the Invention antiltled.

The following statonian, full description of this invention,~ including (lie bast method I performing it known to me -2-

ABSTRACT

A catalytic converter of the automotive type comprises a converter substrate with a reduced central section that compresses a support mat around a substrate, the ends of the body being spherical for attachment to spherical flanges on end bushings or being an integral part of the body. The method of manufacturing the converter substrate and conv':ter is also disclosed.

i o 0 0 Q, 0 lj U 3 THIS INVENTION relates to catalytic converters for internal combustion engine exhaust systems and, it.

particular, to catalytic converters intended for installation in motor vehicles as original equipment by the vehicle manufacturer or as aftermarket replacements for original equipment converters.

Brief Summary of the Invention It is the purpose of the invention to reduce the size and number of parts in a catalytic converter (as compared with known practical constructions) while at the same time increasing its effectiveness and improving its construction and manufacture.

The invention achieves the foregoing purpose by means of a substrate support in the form of a tubular converter body which is reduced in diameter at a central portion to compress a support mat around a catalyst substrate. In one form, the ends of the body are formed to a spherical radius to produce a converter substrate support that can be shipped "as is" or assembled at once into a converter.

This form of converter is completed by attaching inlet and outlet bushings to the ends of the substrate support and this can be done in the factory or at some point downstream. In another form, the body is in two halves, each of which has a bushing formed in it. One of the halves is reduced in diameter to hold the substrate and the other half is pressed over and secured to it.

This invention provides a construction and manufacture that results in a converter that is quite short in length, has few parts, has maximum effectiveness since 100% of the substrate end faces can be used, and has improved accuracy of substrate support, along with other advantages that will become apparent or be mentioned hereinafter.

In one form the invention resides in a converter substrate support for a catalytic converter of the type used in motor vehicle exhaust system comprising, an elongated tubular body, a catalyst substrate inside the body, a support mat surrounding a central portion of the sabstrate, said body having a central reduced diameter portion radially compressed against the mat and the substrate to hole the substrate in position in the body, In a second form the invention resides in a catalytic converter of the type used in motor vehicle exhaust systems comprising an elongated tubular body open at each e d, a catalyst substrate inside the body, a resilient support mat around a central portion of the substrate, said body having a central reduced diameter portion radially compresoed against the mat and the substrate and serving as the substrate support, and gas flow end bushings at opposite ends of the body.

In a third form the invention resides in a method of making a converter substrate support for use in a catalytic converter of the motor vehicle type which compr 4 ses placing an annular shock absorbent support mat around the midsection only of a catalyst substrate, inserting the assembled substrate into a hollow metal body, radially deforming the wall of the metal body into a reduced diameter annular ring in radial contact with said annular mat to apply and retain radial pressure on and radially compress the mat to substantially reduce its thioness and to apply sufficient radial pressure against the substrate to hold the substrate in the body.

In a fourth form the invention resides in a method of making a catalytic converter of the type used in motor vehicle exhaust systems which comprises deforming a first end of a first tubular metal body of uniform diameter into i .4 4 -i 4a a gas flow end bushing, deforming a first end of a second tubular metal body of uniform diameter into a gas flow end bushing, placinq an annular shock absorbent mat around a midsection only of a catalyst substrate, inserting the assembled substrate into a second end of the first body so that the outer end of the mat is radially aligned with the second end of the first body, radially deforming the wall at said second end of the first body into a reduced diameter annular ring in radial contact with the annular mat to apply and retain radial pressure on and radially compress the mat to substantially reduce its thickness and to apply sufficient radial pressure against the substrate to hold the substrate in the first body, and telescoping a second end of the second body over said ring and securing the first and second bodies together.

.liK ai a t a aO r~ Lt 01,0 a 0 t ea a a a aa a a a4 a 0 a a- aa a a a S*aar a a a a a a ar a o a a a 4b Description of the Drawings Figure 1 is a longitudinal cross section along the centerline or axis of a preferred form of converter embodying the invention; Figure 2 is a longitudinal cross section through one half of another form of the invention showing the mat and substrate after stuffing; Figure 3 is a section similar to Figure 2 but showing the parts after reduction in diameter; and Figure 4 is a longitudinal cross section through the completed converter of Figures 2 and 3.

Description of the Preferred Embodiments Referring to Figure 1, a catalytic converter 1 embodying the invention for use in motor vehicle exhaust gas systems comprises an open ended, tubular, preferably round and symmetrical, sheeu metal body 3, the inside of which defines a chamber 5 for a round, symmetrical, ceramic, monolith, honeycomb cell type, catalyst substrtte 7 (available on the open market) having flat ends 9 and a great number of catalyst coated, longitudinal honeycomb cell passages 11 extending from one end 9 to the other.

The central portion of the substrate 7 (less than the full length) is surrounded by an annular, shock absorbent, resilient, insulative, support mat 13, which is preferably composed of a gas impervious vermiculite based material (available on the open market) that expands substantially upon heating. This is preferably about 1/4" thick and radially compressed at assembly to about one half of its initial thickness. The opposite end portions 15 of the Sk a0 a do 9S 0 J o 0 a 0 0 0 body 3 are preferably each formed or swaged to a partially spherical shape as illustrated having central openings substantially less in diameter than the diameter of substrate 7. Gas f low end bushings 17 and 19 have tubular outer ends 21 and 23, respectively, for attachment by welding or clamping, or otherwise, to exhaust system conduits (not shown). They also have outwardly flared annular partially spherical inner end flanges 25 and 27, respectively, each of which is preferably formred on a radius corresponding to that of the body end portions to which Lney are welded in selected locations so tiat their ends 21 and 23 have the desired orientation with respect to tiie centerline or axis of the body 3. End 21 i,7 shown oblique and end 23 is shown coaxial, but many other angular arrangements are accommodated by the mating spherical surfaces.

The body 3 is preferably formed from a length of uniform diameter and thickness metal tubing. The substrate 7, with '-he annular mat band 13 located centrally on it, is positioned centrally in chamber 5 and coaxially inside the tubing which then uniformly reduced in diameter by suitable known means see U.S. Patent No. 3,a82,948, Figures 2 and 2A) into a central, reduced diameter ring portion 29 of aboint the same length as mat 13 thereby uniformly radially teompressing ctne mat atound the outside of the substrate to about -,ne-half its original or free state thickness, thus firmly though somewhat resiliently supporting the substrate in centred position. The ring portion 29 retains radial compression on the mat nd jo the two apply sufficient radial pressure co resiliently retain it in a centred position and serve as the sole means to shock mount and support the ceram~ic monolith, The body 3 has intermediate substantially uniform diameter portions 31. extending between opposite or outer ends of the central ring portion 29 and the inner ends of the spheica. end portions 15. the spherical portions 15 being formed in the metal body 3 after the ring 29 is formed to hold the substrate in place. The portions 31 are radially spaced outwardly from the substrate 7 and preferably extend to about the ends 9 of the substrate whereupon the curvature into spherical end portions lb begins.

If desired, bushings such as 17 and 19 can, after formation of end portions 15, be welded in place at the factory. Alternatively, the converter substrate, or body 3 with the substrate 7 and formed ends 15, can be sent downstream to the vehicle manufacturer, warehouse, repitir shot', etc., where the desired end bushings can be attached to suit specific applications, From the standpoint of a method o~f mainufacture of converter 1, the body 3 is preferably initially in the form of a simple metal tube of uniform diameter, open at bo'.h ends. The mat 13 is placed around th1e midsection of the substrate 7 and this assembly is inserted or stuffed into the tube so that it is longitudinally and radially centred in the tube* While maintaining this centred relationship, the wall of the tube is radially compressed into the reduced diameter ring section 29 whic h, by way of its radial contact with the mat 13, radially compresses it and applies radial pressure to the substrate 7. The radial deformation of rinig 29 is sufficient t~o appl~y -4nd retain enough radial pressure on the mat and substrate to permit shock absorption by the mat but still hold the substrate centred in the tube so that its end corners do not come in contact with the inner wall surface of the tube. After formation of the ring 29 so that the substrate 7 is held in place, radial pressure is applied to the ends of the tube to deform themi inwardly into the spherical -7 cylindrical to preserve the clearance between them and the substrate 7. This completes the converter substrate and the converter is completed by welding the bushings 17 and 19 in place on the end portions 15. Alternatively, one of the spherical end portions 15 could be formed in the body before the substrate is inserted through the other end and held in place by formation of ring 29.

In use, the converter 1 would normally be secured into an exhaust system by welding or clamping of bushing portions 21 and 23 to exhaust system conduits. Either end can be the inlet. Exhaust gas flows through the longitudinal passages 11 which are catalyst coated to reduce oxides of nitrogen and to oxidise hydrocarbons and carbon monoxide in order to achieve acceptable emission levels. If a vermiculite base mat 13 is used, heat from the reaction during initial operation of the converter will cause it to significantly expand thereby enhancing the tightness of the connection between the substrate 7 and body 3 to act along with the relatively high frictional resistance to resist slipping of the substrate relative to the body 3, For the aftermarket. the substrate 7 will be selected, sized and treated with catalyst to produce acceptable emission levels for a wide variety of different engines.

As an example of approximate size for automotive applications, the substrate 7 may be about 4" O.D. and about 5" long, and uniformly spaced about 1/8" from the inner surface of ring 29 and about 1/4" from the inner surface of intermediate portions 31, and the overall length of the body 3 after forming of the spherical ends may be about This is significantly less length than needed to support the substrate in a conventional manner in a similarly shaped body by means of L-shaped support rings. Additionally 100% of the end faces 9 and -8longitudinal passages 11 of the substrate can be- used for p conversion thereby increasing converter effectiveness, A further comparison with the L-ring support method shows that the number of parts in converter 1 has been reduced to only five and that the method of supporting the substrate by uniform radial compression applied through ring 29 achieves more accuracy in manufacturing thereby reducing the likelihood of scrap. The spherical end portions 15 and bilshings 17 and 19 provide a '0"universality" feature that promotes smiller inventory, better service, and lower costs. The body 3, without bushings 17 and 19, comprises a substrate support which can be shipped with reduced likelihood of impact damage to the brittle ceramic substrate material because of the protection provided by the spherical ends and by the unique method of mouniting the substrate which provides ample clearance for the corners of the substrate.

Referiing to Figures 2-4, the invention is illustrated in the form of -a converter 101 (Figure 4) having an elongated, round tubular body 103 containing a catalyst substrate 107 (preferably the same as substrate 7) w it', f lat ends 109 and longitudinal honeycomb cell gas passages Ill extending from one end of face 109 to the other. The central portion ot substrate 107 its surrounded by a F support mat 113 which is preferably the same as mat 13.

Gas flow endi bushings 115 and 117 are preferably integral I) with and formed by swaging or deforming metal in the ends, respectively, of bod halves 119 and 121 which telescope together to form the body, 103, a{alvegw 119 and 121 May be f ormed or swaged and drawn from originally round cylindrio'al tubes that have uniform diameter and wall thickness inner end portions 123 and 125, respectively, 9- Outer portions 127 of the halves are formed into segments that blend into the integral bushings 115 and 117.

Segments 127 are illustrated as spherical, bushing 115 as coaxial with body 103, and bushing 117 as obliqtue to the axi~s of body 103.

As seen in Figure 2, the substrate 1.07 and its central and symmetrically located mat 113 have an outer diameter which is about the same as the inner diameter of end portion 123 of body half 119 whereby the combined substrate and mat can be stuffed into the open end 119a of the half 119 and positioned with the outer end of the mat substantially coplanar with the end 119a (allowance preferably being made for longitudinal mat ex~pansion as a result of radial compression), As seen in Figures 3 and 4, the end of portion 123 is reduced in diameter along section 129 by about the wall thickness of the halves 119 and 121 which is about 50%6 of the original thickness of mat 113. Redluced diameter section 129 is substantially the same in length as the compressed mat.

AS seen from, Figure 4, the open end 121a of half 121 is telescoped over the reduced diameter sectionl 129 of half 119 so that end portion 125 slides over seation 129 for a desired length of overlap, the overlap illustrated in Figure 4 being the length of mat 113 and section 129 though the overlap may be less. Thereafter, the end portion 125 and ha.lf 121 an be affixed to end portion 123 and half 119 asz illustrated by the annular weld 131.

From the standpoint of a Method of manufacture of converter 101, the two halves 119 and 121 are preferably 1) ini.tially each in the form of Simple metal tubes of uniform diameter and open at both ends. One end of each of the halves Is deformed by suitable .4rawing or swaging 10 operations or the like to form sections 127 and the integral bushings 115 and 117 bearing the desired orientation with respect to the axis of the tube. The mat 113 is wrapped around the substrate, preferably being symmetrical with respect to the ends as illustrated, and this assembly stuffed into one of the halves half 119) so that the trailing end of the mat is approximately coplanar with the end of the half end ll9a).

Thereafter, the wall of the half containing the substrate is radially compressed into ring 129, the deformation along a radius preferably being substantially the wall thickness of metal tube from which the halves 119 and 121 are formed, The converter assembly is then oc.npleted by sliding or telescoping the second half half 121) over the ring 129 (which now has an outer diameter that is substantially the same as the inner (iiameter of the second half) for the desired amount of overlap an6 welding or otherwise affixing the two halves together. If both bushings 115 and 117 are oblique to the axis of converter o> 101, the second half will also be angularly positioned in the desired location before it is welded to the first half.

While h,.ves 119 and 121 are shih w.t end bushings 115 and 117, the i4tegral bashn. W7 could be omitted (so that the body 101 iU a .bs'tr? support) and the Vas flow bushings could be ad onss s shown at 17 and 19 for converter I in Figure 1 in which ease it would be important to have 'he end stacont of the halves spherically shaped as shown at i27. Anot' i: modification would be to have spherical ends IA w121b openings at all (except for an ail vtIk ,6r sf purposes, if necessary) whereby tt er o t ht converter would cut the gas fl e desired 11 positions and weld on end cap type bushings such as 17 and 19 of Figure 1. This modification provides maximum protection against damage to the substrate during shipping storage.

For best results, it is important in both converters I and 101 to select the appropriate length for the mat 13 or 113. If the mat is too long, fibres may break off or be liberated by gas pulsations and get into the longitudinal cell passages 11 or 111 and plug them. Also, if the mat is too long a phenomenon known as "ring off" may occur that could produce temperatu e gradients on the substrate that would put it in tension which could lead to cracking in the centre, On the other hand, if the mat is too short, the substrate could rock or resonate causing damage if it impacts on the metal body 3 or 103, The minimise these possibilities, it is desirable that the mat length be in the ranae of 509 to 90% of the substrate length, preferably about 60%. At these lengths, there is special benefit in that it is believed that a static condition develops in the space between the outer diameter of the exposed ands of the hubotrate and the walls of the bodies 3 and 103 wherein the gas is relatively stagnant. This is thought to protect the ends of the mat and tend to minimis. the chance that fibres will come loose and get into the substrate.

Modifications may be made in the specific details shown and described without departing from the spirit and scope of the invention. For example, while spherical end portions 15 are preferred for converter 1, advantawJos of

V,

12 the invention will still be obtained if conventional end cone bushings are attached to sections 31 instead of the flange bushings 17 and 19 that are shown.

Claims

1. A lonverter substrave support for a catalytic converter of the type used in motor vehicle exhaust systems comprising, an elongated tubular body, a catalyst substrate inside the body, a support mat surrounding a central portion of the substrate, said body having a central reduced diameter portion radially compressed against the mat and the substrate to hold the substrate in position in the body.

2. A converter substrate support as set forth in claim 1 S wherein said mat is composed of a material that expands significantly upon heating and thereby increases the radial compression between the substrate and reduced diameter portion.

3. A converter substrate support as set forth in claim 1 wherein said body has cylindrical portions extending longitudinally away from opposite sides of said reduced portion and radially spaced from the outer surface of the substrate by an amount substantially greater than the thickness o'4 the mat,

4. A converter substrate support as set forth in claim 3 wherein said iat and central portion are substantially equal in length, A converter substrate support as set forth in claim 1 wherein said mat is composed of fibrous material and the length of the mat is about 50-90% of the length of the substrate. S-14-

6. A converter substrate support as set forth in claim 1 wherein the body is open at the ends and has end portions adapted to be attached to gas flow end bushings.

7. A converter substrate as set forth in claim 6 wherein said end portions are spherically shaped.

8. A converter substrate support as set forth in claim 1 wherein the body is closed at the ends.

9. A converter substrate support as set forth in claim 8 wherein said body has spherically shaped end portions. A converter substrate support as set forth in claim 1 wherein said body comprises one piece and said central portion is formed in said one piece. 11, A converter substrate support as set forth i:L claim 1 wherein said body comprises two sections telescoped together and said reduced diameter central portion is formed in an end of one of the sections and the other S. section fits over said reduced diameter central portion. 12, A catalytic converter of the type used in motor vehicle exhaust systems comprising an elongated tubular body open at each end, a catalyst substrate inside the body, a resilient support mat around a central portion of the substrate, said body having a central reduced diameter portion radially compressed against the mat and the substrate and serving as the substrate support, and gas flow end bushings at opposite ends of the body. 13, A converter as set forth in claim 12 wherein the end portions of the body are spherically shaped and said end 4* 15 bushings have spherically shaped flanges attached to said spherical end portions.

14. A converter as set forth in claim 12 wherein the body comprises one piece and said central reduced diameter portion is formed in said one piece. A converter as set forth in claim 12 wherein said body comprises two sections telescoped together and said reduced diameter central portion is formed in an end of one of the sections and the other section fits over said reduced diameter central portion.

16. A converter as set forth in claim 12 wherein the mat aind central reduced diameter portion serve as the sole support means for the substrate.

17. A converter as set forth in claim 16 wherein the mat and central reduced diameter portion are substantially coextensive in length and such length is within the range of about 50-90% of the length of the substrate.

18. A converter as set forth in claim 17 wherein such 1 is about 60% of the length of the substrate. A converter as set forth in claim 12 wherein at least one of the gas flow end bushings is oblique to the axis of the body. A converter as set forth in claim 12 wherein said mat is composed of a heat expandable fibrous material and has a length substantially within the range of about 50-90% of the length of the substrate, said mat being compressed by said central reduced diameter portion to about one half of its free state thickness. 16

21. A converter as set forth in claim 20 wherein said body has cylindrical wall portions radially spaced from the end portions of the substrate projecting beyond said mat for a distance substantially the same as that of the projecting ends of the substrate, said radial spacing being substantially the same as said free state thickness of the mat.

22. A converter as set forth in claim 21 wherein said body has end portions extending outwardly from the outer ends of said cylindrical wall portions and said end portions being spherically shaped.

23. A converter as set forth in claim 22 wherein said end portions commence in planes substantially coincident with the end faces of the substrate.

24. A method of making a converter substrate support for use in a catalytic converter of the motor vehicle type which comprises placing an annular shock absorbent support mat around the midsection only of a catalyst substrate, inserting the assembled substrate into a hollow metal body, radially deforming the wall of the metal body into a reduced diameter annular ring in radial contact with said annular mqt to apply and retain radial pressure on the mat and radially compress the mat to substantially reduce its thickness and to apply sufficient radial pressure against the substrate to hold the substrate in the body. A method as set forth in claim 24 including the added step of applying radial pressure to an outer end of the body to radially deform it inwardly into an end portion of predetermined shape. T>A S^0 0 A. i I 6 fc^ fl tt f O O e 4 17

26. A method according to claim 24 wherein the assembled substrate is inserted into the body to that it is longitudinally and axially centred in the body and wherein a central portion of the wall of the body is deformed into said annular ring.

27. A method according to claim 24 wherein the assembled substrate is inserted into a first body wherein one end portion of the substrate extends beyond the mat out of the first body and wherein said end portion of the wall of the first body is deformed into said annular ring and including the steps of telescoping a second hollow metal body over said annular ring and securing the second body to the first body in said telescoped condition, and wherein the assembled substrate is axially centred in the first and second body when in said telescoped condition. 28, A method of making a catalytic converter of the type used in motor vehicle exhaust systems which comprises deforming a first end of a first tubular metal body of uniform diameter into a gas flow end bushing, deforming a first end of a second tubular metal body of uniform diameter into a gas flow end bushing, placing an annular shock absorbent mat around a midsection only of a catalyst substrate, inserting the assembled substrate into a second end of the first body so that the outer end of the mat is radially aligned with the second end of the first body, radially deforming the wall at said second end of the first body into a reduced diameter annular ring in radial contact with the annular mat to apply and retain radial pressure on and radially compress the mat to substantially reduce its thickness and to apply sufficient radial pressure against the substrate to hold the substrate in the first body, and telescoping a second end of the second body over said ring and securing the first and second bodies together. 4 7W coo 18

29. A method according to claim 28 including deforming the wall of the first end of the first body by a radial distance substantially the same as the wall thickness of the first end of the second body. A converter substrate support substantially as hereindescribed with reference to the accompanying drawings.

31. A method of making a converter substrate support substantially as hereindescribed with reference to the accompanying drawings.

32. A catalytic hereindescribed with drawings. converter reference substantially as to the accompanying

33. A method of making a substantially as hereindescribed accompanying drawings. catalytic converter with reference to the DATED this FOURTH day of APRIL 1990 0i ~~0 00 0ro 00i TENNESSEE GAS PIPELINE COMPANY Applicant. WRAY ASSOCIATES, Perth, Western Australia, Patent Attorneys for the Applicant.