US3100140A

US3100140A - Catalytic automotive exhaust converter

Info

Publication number: US3100140A
Application number: US32678A
Authority: US
Inventors: Paul R Ashley; David D Laing
Original assignee: Calumet and Hecla Inc
Current assignee: Calumet and Hecla Inc
Priority date: 1960-05-31
Filing date: 1960-05-31
Publication date: 1963-08-06
Anticipated expiration: 1980-08-06

Description

Aug. 6, 1963 P. R. ASHLEY ETAL 3,100,140

CATALYTIC AUTOMOTIVE EXHAUST CONVERTER Filed May 31, 1960 INVEI'Z: RS PAU .ASHL

DAV .LAING ATTORNE S United States Patent 3,100,140 CATALYTIC AUTOMOTIVE EXHAUST CONVERTER Paul R. Ashley, Livonia, and David D. Laing, Detroit, M ch assignors to Calumet & Hecla, Inc., Allen Park, Mich., a corporation of Michigan Filed May 31, 1960, Ser. No. 32,678 6 Claims. (Cl. 23-288) This invention relates to a catalytic automotive exhaust converter and method of making the same.

One object of this invention is to provide a catalytic automotive exhaust converter for use in the exhaust line of an internal combustion engine to remove unburned hydrocarbons and other objectionable components from the exhaust gases, which converter is designed to be highly eflicient in the performance of its intended function.

Another object of the invention is to provide a catalytic automotive exhaust converter which is less expensive to manufacture than prior art converters of this type.

A further object of the invention is to provide an exhaust converter comprising a casingv having a chamber therein, a plurality of superimposed sheet layers in the chamber which are corrugated in the same direction and the peaks of which engage one another to define channels, and catalytic material in the channels to accelerate the oxidation of the unburned hydrocarbons passing through the channels.

Still another object of the invention is to provide an exhaust converter as described above in which the peaks of the corrugations of alternate sheets are formed with generally V-shaped longitudinal recesses receiving the peaks of the corrugations of the remaining sheets to provide a mechanical interlock.

Another object of the invention is to provide an exhaust converter as described above in which the body of the casing is formed from a single corrugated sheet of material spirally rolled upon itself, the peaks of certain of the corrugations being recessed so that the corrugations of overlying layers form a mechanical interlock.

Another object of the invention is to provide a method of making the exhaust converter described above.

Other objects and features of the invention will become apparent as the description proceeds, especially when taken in conjunction with the accompanying drawings, wherein:

FIGURE 1 is a perspective view of a catalytic automotiveexhaust converter constructed according to our invention.

FIGURE 2 is an enlarged fragmentary perspective view of one end of the converter with parts removed to illustrate the interior construction.

FIGURE 3 is an end view of the structure shown in FIGURE 2.

FIGURE 4 is a sectional view taken on the line 44 of FIGURE 3.

FIGURE 5 is an enlargement of a portion of FIG- URE'3.

FIGURE 6 is a perspective view showing an intermediate step in the construction of the converter.

Referring now more particularly to the drawings, the exhaust converter there shown comprises the elongated casing 10 which has an outer tubular wall 12 and an inner tubular wall 14 which cooperate to define an elongated annular chamber 16 between the walls of the casing.

The inner and outer Walls of the casing, as well as the interior sheet layers thereof, described more fully hereinafter, are formed from a single elongated sheet 20 which may be aluminized steel, for example, or any other suitable high heat conductivity material. The sheet is notched along both of its longitudinal edges to provide the intermediate section 22 of uniform width, the

ends

24 and 26 of the sheet being relatively broad and of the same width. The intermediate section 22 of the sheet is transversely corrugated throughout its length, as shown. The end 26 has a transverse fold 27 near the corrugated intermediate section and a transverse flange 29 along its edge.

In order to build the converter, the broad end portion 24 of the sheet 20 is folded upon itself to provide the elliptical inner wall 14 and seam welded at the joint 28. The seam weld extends along the inner traverse edge of the broad portion 24, joining the already formed inner wall 14 to the intermediate section 22 in a continuous weld at the point where they diverge. The inner wall 14 thus forms an air-tight tube. Thereafter, the corrugated intermediate section of the sheet is spirally wrapped about the inner wall 14 of the casing to provide a plurality of sheet layers, as shown in FIGURE 3. All of the corrugations are generally V-shaped. The corrugations of the first layer or spiral are formed with generally V-shaped recesses 30 which extend from end to end of the corrugations and are formed to receive the peaks of certain corrugations of the outer layer or spiral. Hence the corrugations of one layer are mechanically interlocked with the corrugations of the other layer. In the particular design shown, it was found desirable to' locate four peaks 31 in positions other than on the V-shaped recesses 30.

In the present embodiment, only two layers of corrugations are provided. However, it will be appreciated that additional layers or spirals of the corrugated intermediate section of the casing may be provided, in which event the corrugations of alternate layers will be formed with the V-shaped recesses in their peaks to receive the peaks of the corrugations of the adjacent layers. Channels 34 are defined by the corrugations.

The sheet 20 is completely wrapped upon itself so that the broad end section 26 provides an outer Wrap and defines the outer wall 12 of-the casing. When the final router wrap is made, the flange 29 is hooked over the told 27 and the two are flattened down substantially parallel to the surface of the outer wall 12 of the converter. This is one preferred means for securing the outer wrap. It will be understood that other means may be employed. For example, the end of the outer wrap may simply be seam welded. Clearly other suitable means for fastening the outer wrap may be provided. It will be appreciated that the length of the casing is equal to the width of the

end portions

24 and 26 and that the channels 34 defined between the corrugations of adjacent sheet layers are shorter than the casing. The purpose of this is to provide the

chambers

36 and 38 at opposite ends of the casing, more fully described hereinafter.

Annular screens 42 are shaped to fit closely within the outer wall 12 and to fit closely about the inner wall '14, and are inserted within the ends of the casing. Any suitable means may be employed to securely fasten the screens in position against the ends of the channels so that the catalyst cannot escape and so that channeling cannot occur. In the present instance, the screens are shown by way of example as having retainer rings 43 spot welded to the casing. First, one of the screens is installed in position and the casing is placed on end and then granulated catalytic material is poured into the channels 34 until they are filled. Then the other screen is installed. The screen apertures are somewhat smaller than the grains of catalyst to contain them without interfering with the flow of exhaust gases through the channels.

The annular end closure members 44 are identical. They are formed with inner annular flanges 46 having a close fit about the inner wall 14 of the casing, and outer annular flanges 48 having a close fit within the outer wall 12 of the casing. Any suitable means may be provided to securely fasten the end closure members in positi'on at the endsof the casing so that the space between the end closure members is relatively leak-proof. In the present instance, and by way of example, the flanges are shown as welded to the casing, although it will be obvious that other equally satisfactory fastening means may be employed. For example, instead of welding, the end members 44 may be rolled, crimped, or fastened in any other way to form an air tight seal around the inner wall 14 and the outer wall 12. One end member is formed with an exhaust inlet 50 and the other with an exhaust outlet 52. These inlets and outlets may also be secured to the end menrbers by rolling, welding or any suitable means which provides an airtight seal. The

chambers

36 and 38 are defined between the screens and end members and are in direct communication with the catalyst channels 3 4. The inlet 50' and outlet 52 are at opposite sides of the center tube 14 to assure a better distribution of gases inside the converter.

No catalytic converter based on the oxidation of hydrocarbons can be effective unless there is sufiicient oxygen introduced to complete the combustion of the unburned hydrocarbons. Any other suitable air inspiration devices may be used to provide the necessary secondary air. The secondary air may, for example, be introduced by devices such as a venturi, a flat-plate orifice or a pump. The particular means for introducing the secondary air forms no part of this invention and therefore it should be understood that the converter may be used in conjunction with any suitable means for introducing secondary air.

The catalyst may be any suitable material designed to promote oxidation of the unburned hydrocarbons in the exhaust gases passing through the converter. Vanadium pento-xide (V has been found to be a very effective catalyst for this purpose. as those of chromium, manganese, copper, nickel, iron and molybdenum might provide suitable catalysts. Since all catalysts act only on their surface, they are usually coated on a granulated carrier. The dimensions of the granulated catalytic material are not critical but they should not be so small as to pass through the retaining screen or to pack in a solid mass.

The sheet 20 is formed of a high heat conductivity material to rapidly dissipate the heat generatedin the. converter. The channels break up and uniformly distribute the catalytic bed so that it is kept at a more or less uniform temperature, thereby avoiding the for mation of hot spots.

The corrugations engage each other and engage the inner and outer walls of the casing, but they may yield, or move, relative to one another to avoid damage due to mechanical and thermal shock. In this connection the peaks of the corrugations which engage each other as well as the inner and

outer walls

12 and 14 are, at least throughout a major part of the length of such engagement, not fixedly secured in position. In some. in-. stances the entire length of engagement of the peaks of the corrugations are free of any fastening means. However, in other instances it is desirable to weld or otherwise fasten the peaks of the corrugations at the ends of the channels so that the size of the converter can be closely controlled. Too much movement can ac-. tually be a detriment since it can grind the catalyst and allow it to move from one channel to another. Therefore it is desirable to provide a small amount of flexibility to avoid crushing the catalyst due to mechanical and thermal shock and movements but the flexibility should be so limited that the catalyst will not 'be actually ground up in the process and the dimensions of the entire converter can be properly controlled during manufacture.

The channels have the further function of muffling noise by breaking up the stream of gas. Basically, this is a process of dividing the gas stream up into a number of Other oxides such 4 small channels so that as the sound waves pass out of the end of the converter they interfere with each other to partially cancel the noise of the engine explosions.

The inner wall 14 of the casing defines a. through passage for air to facilitate cooling olf the converter. In some instances it may be desirable to provide an integral corrugated extension 56 of the broad end portion 24 which will bedisposed within the tubular wall 14 in contact therewith to serve as a reinforcement and as an additional surface for the dissipation of heat.

In designing and constructing a converter of this type, the first step is to secure the following information:

1) The required catalyst section volume based on the amount of catalyst needed.

(2) The catalyst density.

(3) The physical dimensions of the place where the converter is to be located.

(4) The size of the inlet and outlet pipes if predetermined by the end use.

Using the above information, it is possible to determine the height, width, and length of the converter.

The following points must be considered when designing for automobile use.

1) Heat transfer: Design for maximum allowable outside surface including the center cooling tube.

(2) Pressure drop across converter:

(a) Design for shortest catalyst bed length.

(b) Design to eliminate sharp turns in gas flow; for example, keep plenum chambers as large as practical.

(3) Mechanical strength: Design for curved surfaces.

After the outside and center tube dimensions have been determined, the corrugated cross section is next considered. In deciding the inside configuration, all factors which affect channel size must be considered.

(1) The type of catalyst used must be considered. A soft, irregular shaped, rough surfaced, easily broken up catalyst requires smaller channels than a hard, smooth surfaced, pelleted type.

(2) The amount of metal, and consequently the tinished weight of the converter, depends on the size of the corrugations.

(3) Among other things, the attenuation qualities depend on the size of the channels.

4) The mechanical strength depends on the thickness of the material and the number of channels. The smaller the channels the closer together the peaks will be around the center tube and the outer casing. The number of layers will be decided by the channel size desired. The first wrap automatically decides the number of peaks in the second and any succeeding layers. There must be one peak in the first layer for each peak desired in the second, third, or whatever layer is the final layer in direct contact with the outer casing. A rule of thumb could be stated that the average channel area is from 2.5% to 5% of the total cross sectional area channel of the casing.

After the desired channel size has been approximated, the outer casing and the center cooling tube are laid out, in relation to each other, on paper. When this layout is made, the distance on the flat plane from the outer casing to the center tube is divided in half and a line is scribed parallel to the flat surfaces at this point. The perimeter of the cooling tube is divided into the desired number of corrugations. The distance between any two of these points now becomes the base of a general triangle. A point on the outer casing is located for each point on the cooling tube. This can be done by projection. On the circular ends of the casing, it is often desirable to change the location of these points to gain meo'hanical strength or to equalize the size of the channels. In this particular design, we found it necessary to locate four peaks on the outer wrap. in positions other than on V-shaped recesses of the first layer. After these points have been located, they too form the base of a general triangle which is inverted from the first triangle.

The next step is to locate a point midway between these sets of points on the previously scribed line. This point, when connected to the two points on the outer casing, forms a triangle which becomes the outer layer. The next step is to determine the desired depth of the interlock. After the depth has been decided, the designer should measure up on the already form-ed outer triangle and locate the two points. These points, when connected to the points on the center cooling tube, form the inner or first channel. When :a pair of adjacent inner and outer channels connect in the interlock, they form between them a diamond shaped channel.

After the size and shape of the corrugations have been determined, the next step is to lay out the configuration using one continuous line representing the single sheet construction. When preparing this, again, some important considerations must be noted:

(1) Weld locations should be readily accessible.

(2) Doubling the sheet should be avoided when it must fit into an interlock or at any point where it might, when heated, open up and permit direct channeling of the exhaust gases.

Only one step remains before construction of the casing can begin. This step is to translate the design to a dimensioned drawing. This can be done in any manner desired.

The drawings and the foregoing specification constitute a description of the improved catalytic automotive exhaust converter and method of making the same in such full, clear, concise and exact terms as to enable any person skilled in the art to practice the invention, the scope of which is indicated by the appended claims.

What we claim as our invention is:

1. A catalytic exhaust gas converter comprising a casing having a chamber therein extending longitudinally a substantial distance in a direction from an inlet end to an outlet end, a plurality of superimposed heat conductive sheet layers in said chamber, adjacent layers being corrugated to provide peaked portions which extend longitudinally in the direction of and parallel to said chamber, with the depth of said corrugations being transverse of said direction, said corrugated layers engaging one another to define laterally enclosed rectilinear channels open at opposite ends thereof, each channel being of substantially uniform cross sectional area along the length thereof, granular catalytic material in said channels substantially filling the same as subdivided masses of said material, and foraminated members at said opposite ends of said channels confining said catalytic material therein, said casing having inlet and outlet ports adjacent said inlet and outlet ends which communicate respectively through said foraminated members with said opposite ends of said channels for the passage of exhaust gases through said catalytic material in the channels, said channels being individually in heat conductive and physically supporting relation to the respective subdivided masses of the material in the respective channels.

2. A catalytic exhaust gas converter comprising a casing having a chamber therein extending longitudinally a substantial distance in a direction from an inlet end to an outlet end, a plurality of superimposed heat-conductive sheet layers in said chamber, adjacent layers being corrugated to provide peaked portions which extend longitudinally in the direction of and parallel to said chamber, with the depth of said corrugations being transverse of said direction, a substantial number of the peaked portions of the corrugations of one layer engaging those of the corrugations of an adjacent layer to define laterally enclosed rectilinear channels open at opposite ends thereof, each channel being of substantially uniform cross sec tional area along the length thereof, granular catalytic material in said channels substantially filling the same as subdivided masses of said material, and foraminated members at said opposite ends of said channels confining said catalytic material therein, said casing having inlet and outlet ports adjacent said inlet and outlet ends which communicate respectively through said foraminated members with said opposite ends of said channels for the passage of exhaust gases through said catalytic material in the channels, said channels being individually in heat conductive and physically supporting relation to the respective subdivided masses of the material in the respective channels.

3. An exhaust gas converter in accordance with claim 1, in which said casing and channel-defining layers are integral parts of a single sheet of heat conductive material spirally wrapped upon itself to constitute said chamber and passages.

4. An exhaust gas converter in accordance with claim 2, in which said casing and channel-defining layers are integral parts of a single sheet of heat conductive material spirally wrapped upon itself to constitute said chamber and passages.

5. An exhaust gas converter in accordance with claim in which said engaged peaked portions of adjacent layers have mating formations at the zone of engagement thereof to provide a mechanical interlock of said portions.

6. An exhaust gas converter in accordance with claim 4, in which said engaged peaked portions of adjacent layers have mating formations at the zone of engagement thereof to provide a mechanical interlock of said portions.

References Cited in the file of this patent UNITED STATES PATENTS 1,113,151 Chisholm Oct. 6 ,1914 2,361,691 Jendrassik Oct. 31, 1944 2,526,657 Guyer Oct. 24, 1950 2,576,213 Chausson Nov. 27, 1951 2,834,657 Houdry May 13, 1958 2,853,367 Karol et al Sept. 23, 1958 FOREIGN PATENTS 1,332 Great Britain Nov. 6, 1913 1913 137,556 Switzerland Mar. 17, 1930

Claims

1. A CATALYTIC EXHAUST GAS CONVERTER COMPRISING A CASING HAVING A CHAMBER THEREIN EXTENDING LONGITUDINALLY A SUBSTANTIAL DISTANCE IN A DIRECTION FROM AN INLET END TO AN