Exhaust treatment apparatus and method of making

Abstract

An exhaust treatment apparatus including a core having a substrate contained within an outer casing is disclosed. The exhaust treatment apparatus also includes a sizing structure that projects radially outwardly from the outer casing of the core. The sizing structure has an outer size that corresponds to the inner size of a muffler or other structure into which it is desired to mount the exhaust treatment apparatus.

Description

FIELD OF THE INVENTION

[0002] The present invention relates generally to exhaust treatment devices having cores such as catalytic converters or diesel particulate filters.

BACKGROUND OF THE INVENTION

[0003] To reduce air pollution, vehicle emissions standards have become increasingly more stringent. With respect to both internal combustion and diesel engines, catalytic converters have been used to reduce the concentration of pollutant gases (e.g., hydrocarbons, carbon monoxide, nitric oxide, etc.) in the exhaust stream. Also, with respect to diesel engines, diesel particulate filters have been used to reduce the concentration of particulate matter (e.g., soot) in the exhaust stream.

[0004] A typical catalytic converter includes a substrate mounted in an outer casing or “can.” The substrate defines a plurality of longitudinal channels that extend through the catalytic converter. Exemplary substrate materials include ceramic and corrugated metal. A catalyst is provided on the substrate for promoting the oxidation of a gaseous pollutant. For example, to promote the oxidation of hydrocarbons or carbon monoxide, the catalyst can include a noble metal such as platinum, palladium or rhodium.

[0005] A typical diesel particulate filter includes a ceramic substrate mounted in an outer casing. The ceramic substrate is porous and defines a plurality of longitudinal channels. Adjacent longitudinal channels are plugged at opposite ends of the core as described in U.S. Pat. No. 4,851,015 that is hereby incorporated by reference in its entirety. The plugged ends forces exhaust gases to flow through the walls of the substrate so that soot is collected on the walls as the gases pass therethrough. For some applications, a catalyst can be provided on the substrate such that the filter functions like a catalytic converter to reduce the concentration of pollutant gases such as hydrocarbons and carbon monoxide.

SUMMARY OF THE INVENTION

[0006] One aspect of the present invention relates to an exhaust treatment apparatus including a core having a substrate contained within an outer casing. The exhaust treatment apparatus also includes a sizing structure that projects radially outwardly from the outer casing of the core. The sizing structure has an outer size that corresponds to the inner size of a muffler or other structure into which it is desired to mount the exhaust treatment apparatus.

[0007] Another aspect of the present invention relates to a method for mounting an exhaust treatment apparatus in a muffler. The exhaust treatment apparatus includes a core having a substrate contained within an outer casing. The method includes manufacturing the core a predetermined amount smaller than the muffler. The method also includes providing a sizing structure that extends radially outwardly from the outer casing. The method further includes sizing the sizing structure to correspond to the internal dimensions of the muffler, and subsequently positioning the core into the muffler.

[0008] A variety of other aspects of the invention are set forth in part in the description that follows, and in part will be apparent from the description, or may be learned by practicing the invention. The aspects of the invention relate to individual features as well as combinations of features. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] FIG. 1A is a side view of a prior art catalytic converter;

[0010] FIG. 1B is an end view of the catalytic converter of FIG. 1A;

[0011] FIG. 2A is a longitudinal cross-sectional view of a catalytic converter that is an embodiment of the present invention, the catalytic converter has curled sizing structures and is shown mounted in a muffler;

[0012] FIG. 2B is an end view of an oval embodiment of the catalytic converter of FIG. 2A;

[0013] FIG. 2C is an end view of a round embodiment of the catalytic converter of FIG. 2A;

[0014] FIG. 3 shows the catalytic converter of FIG. 2A prior to forming the end sizing structures;

[0015] FIG. 4 is a longitudinal cross-sectional view of a catalytic converter that is an embodiment of the present invention, the converter has sizing structures that are partially curled;

[0016] FIG. 5 is a longitudinal cross-sectional view of a catalytic converter that is an embodiment of the present invention, the converter has sizing structures that include straight radial flanges aligned perpendicular to a central axis of the converter;

[0017] FIG. 6 is a longitudinal cross-sectional view of a catalytic converter that is an embodiment of the present invention, the converter has sizing structures that include straight radial flanges aligned at an oblique angle relative to a central axis of the converter;

[0018] FIG. 7A is a longitudinal cross-sectional view of a catalytic converter that is an embodiment of the present invention, the converter has sizing structures that include baffles connected to an outer casing of the converter;

[0019] FIG. 7B is an end view of the catalytic converter of FIG. 7A;

[0020] FIGS. 8A and 8B show a catalytic converter that is an embodiment of the present invention, the converter has sizing structures that include oval baffles connected to an oval outer casing of the converter;

[0021] FIGS. 9A and 9B show a catalytic converter that is an embodiment of the present invention, the converter has sizing structures that include oval baffles connected to a round outer casing of the converter;

[0022] FIGS. 10A and 10B show a catalytic converter that is an embodiment of the present invention, the converter has sizing structures that include round baffles connected to an round outer casing of the converter;

[0023] FIGS. 11A and 11B show a catalytic converter that is an embodiment of the present invention, the converter has sizing structures that include round baffles connected to an oval outer casing of the converter;

[0024] FIGS. 12A and 12B show a catalytic converter that is an embodiment of the present invention, the converter has sizing structures that include baffles having deformable retaining tabs;

[0025] FIGS. 13A and 13B show a catalytic converter that includes a condensation capturing structure;

[0026] FIG. 14 shows a catalytic converter with an alternative condensation capturing structure;

[0027] FIG. 15 shows a catalytic converter with another alternative condensation capturing structure;

[0028] FIG. 16 shows a muffler system including a catalytic converter with still another condensation capturing structure; and

[0029] FIG. 16A is a detailed view of a portion of FIG. 16.

[0030] While the invention is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail below. It is to be understood, however, that the intention is not to limit the invention to the particular embodiments described. On the contrary, the invention is intended to cover all modifications, equivalents, and alternatives falling within the scope of the invention as defined by the appended claims.

DETAILED DESCRIPTION

[0031] In the following detailed description, references are made to the accompanying drawings that depict various embodiments in which the invention may be practiced. It is to be understood that other embodiments may be utilized, and structural and functional changes may be made without departing from the scope of the present invention.

[0032] FIGS. 1A and 1B show a prior art catalytic converter 20 having a core including a substrate 22 contained within an outer “can” or casing 24. The substrate 22 is a corrugated metal substrate of the type shown in FIG. 7 of U.S. Pat. No. 5,355,973, which is hereby incorporated by reference in its entirety. A noble metal catalyst such as platinum or palladium is provided on the substrate 22. As shown in FIG. 1B, the casing 24 and the substrate 22 are oval in shape.

[0033] To mount the catalytic converter 20 in an oval structure such as an oval muffler or an oval stand-alone catalytic converter shell, it is desirable for the X and Y dimensions of the casing 24 to be manufactured within relatively tight tolerances (e.g., plus or minus 0.030 inches). If the casing 24 has outer dimensions larger than those specified, the core can be over-compressed as the core is fit within the muffler causing the catalyst to crack or flake. If the outer casing 24 has outer dimensions smaller than those specified, it can be difficult to form a circumferential seal (e.g., with a weld) between the casing 24 and the muffler. Absent an effective seal, exhaust gases can leak around the catalytic converter 20.

[0034] It is difficult to maintain the desired X and Y manufacturing tolerances along the entire length of the outer casing of an oval catalytic converter having a corrugated metal substrate. To overcome this problem, the inventors have invented various sizing structures adapted to project outwardly from a catalytic converter. The sizing structures can be manufactured with outer dimensions maintained within relatively tight manufacturing tolerances. While the various aspects of the present invention are particularly applicable to oval catalytic converters having corrugated metal substrates, the aspects are also applicable to round catalytic converters as well as catalytic converters having ceramic substrates such as those disclosed in U.S. Pat. No. 5,355,973, which is hereby incorporated by reference. Further, the various aspects of the present invention are also applicable to other types of devices such as diesel particulate filters, and NOx (Nitric Oxide) traps/absorbers. Moreover, as used herein, the term “catalytic converter” means a device with a substrate including a catalyst. Exemplary categories of catalysts include carbon monoxide (CO) catalysts, hydrocarbon (HC) catalysts, lean NOx catalysts and selective reduction catalysts. Exemplary catalysts include noble/precious metal catalysts such as platinum, palladium or rhodium, or other types of catalysts such as base metal zeolites.

[0035] FIG. 2A shows a catalytic converter 30 that is an embodiment of the present invention. The catalytic converter 30 includes core having a substrate 32 (e.g., a corrugated metal or ceramic substrate) positioned within an outer can or casing 34. In the case of a metal substrate (e.g., a foil or corrugated metal substrate), the substrate can be retained within the casing 34 by conventional mechanical means such as a weld. Alternatively, a metal or a ceramic substrate can be held within the casing 32 by forming “beads” or other types of projections that extend radially inwardly from the casing 34 and engage or abut against the ends of the substrate. A catalyst such as a noble metal catalyst is provided on the substrate 32. The catalytic converter 30 is shown mounted in a muffler 36 or other type of shell such as a stand-alone catalytic converter shell. In one embodiment, the catalytic converter 30 and the muffler 36 have an oval transverse cross-section as shown in FIG. 2B. FIG. 2C shows an alternative catalytic converter 30′ having a round transverse cross-section. The converter 30′ is adapted to fit within a muffler 36′ having a round transverse cross-section.

[0036] Referring back to FIG. 2A, the casing 34 preferably is constructed with a core dimension D1 selected to be smaller that a corresponding inner dimension D2 of the muffler 36. Preferably, the core dimension D1 is {fraction (3/16)} inch to ½ inch smaller than the inner dimension D2 of the muffler 36. Because the core dimension D1 is smaller than the dimension D2, an air gap 38 is provided between the outer casing 34 and the wall of the muffler 36 when the catalytic converter 30 is mounted therein.

[0037] The catalytic converter 30 also includes sizing structures that compensate for the difference in size between the core dimension D1 and the dimension D2. The sizing structures are sized to traverse the distance of the air gap 38 and are adapted to contact the inner surface of the muffler 36 about the entire perimeter of the converter 30. The sizing structures are formed by unitary or integral extensions 41 of the casing 34 that extend axially beyond the ends of the substrate 32 (see FIG. 3). As shown in FIG. 2A, the extensions 41 have been curled over to form sizing structures in the form of radial projections 42 that extend radially outwardly from the outer casing 34 (i.e., away from a central axis of the casing). The projections 42 extend about the outer boundary of the casing 34 and are sized so that outermost portions 43 define X and Y dimensions that are within relatively precise manufacturing tolerances. For example, the X and Y dimensions of the outermost boundary of the converter 30, as defined by the projections 42, are preferably manufactured to a manufacturing tolerance of at most plus or minus 0.030 inches. While the broad concept of the invention is not limited to any particular size of projection, the projections 42 preferably have a radial dimension D3 that is less than 1 inch, or more preferably in the range of {fraction (3/32)} inch to ¼ inch.

[0038] The sizing structures eliminate the need for the X and Y dimensions of the outer casing 34 to be precisely toleranced along the entire length of the core. Instead, the relevant X and Y dimensions of the converter are defined at the relatively discrete locations of the sizing structures that are preferably relatively precisely sized.

[0039] To mount the catalytic converter 30 in the muffler 36, the converter 30 is pushed axially into the interior of the muffler 36. The taper of the leading sizing projection 42 facilitates inserting the converter 30 into the muffler 36 (i.e., the projection 42 functions as a “lead-in”). Axial ends 45 of the sizing projections 42 provide broad contact surfaces for pushing the converter 30 into the muffler 36 without contacting the substrate 32. When the converter 30 is positioned in the muffler 36, the sizing projections 42 can provide an interference fit boundary that limits/prevents leakage or “blow-by.” The sizing projections 42 also provide a pocket 47 about the perimeter of the catalytic converter 30 that facilitates forming an effective circumferential weld (e.g., either continuous or intermittent) between the sizing projections 42 and the muffler 36. The weld further prevents leakage past the catalytic converter 30.

[0040] The sizing projections 42 preferably, but not necessarily, provide an interference with the muffler 36. Because the sizing projections 42 contact the muffler 36 at relatively small contact areas, the interference fit does not interfere with the ability to push the converter 30 into the muffler 36.

[0041] Referring to FIG. 2A, when the catalytic converter 30 is mounted in the muffler, the air gap 38 is defined between the casing 34 and an inner surface of the muffler 36. The air gap 38 functions as an insulating layer or thermal barrier that prevents the outer portion of the substrate 32 from cooling below predetermined levels. By maintaining relatively high temperatures throughout the entire cross-sectional area of the substrate 32, the efficiency of the catalytic converter is enhanced. Further, the air gap 38 reduces the likelihood that a band or clamp mounted around the muffler 36 would crush the substrate of the converter.

[0042] FIG. 4 shows a catalytic converter 30a that is the same as the catalytic converter 30 of FIG. 2A except that sizing projections 42a are only partially curled. FIG. 5 shows a catalytic converter 30b that is the same as the catalytic converter 30 of FIG. 2A except that sizing projections 42b are shown as straight flanges that project radially outwardly in a direction generally perpendicular to a central axis A-A of the converter 30b. FIG. 6 shows a catalytic converter 30c that is the same as the catalytic converter 30 of FIG. 2A except that sizing projections 42c are shown as straight flanges that project radially outwardly at an oblique angle relative to a central axis A-A of the converter 30c. FIGS. 7A and 7B show a catalytic converter 30d that is the same as the catalytic converter 30 of FIG. 2A except that sizing projections 42d are formed by separate baffles 50 connected (e.g., welded) to ends 52 of outer casing 34d.

[0043] FIGS. 8A and 8B show a catalytic converter 130 having outer casing 134 containing substrate 132. Baffles 150 are mounted to the ends of the casing 134. For example, the baffles 150 can be welded to the axial end faces of the casing 134. The baffles 150 have central openings 154 for preventing the downstream and upstream faces of the substrate 132 from being blocked. Portions of the baffles 150 can radially overlap the substrate 132 to “capture” the substrate 132 within the casing 134. The baffles 150 also include sizing projections 141 that project radially outwardly from the outer casing 134. In this embodiment, the casing 134, the openings 154 and the outer boundary of the baffles 150 are all oval is shape.

[0044] FIGS. 9A and 9B show a catalytic converter 130a that is the same as the converter 130 of FIGS. 8A and 8B except that baffles 150a define round openings 154a that correspond to a round core. FIGS. 10A and 10B show a catalytic converter 130b that is the same as the converter 130 of FIGS. 8A and 8B except that baffles 150b have a round outer boundary and define round openings 154b that correspond to a round core. FIGS. 11A and 11B show a catalytic converter 130c that is the same as the converter 130 of FIGS. 8A and 8B except that baffles 150c have a round outer boundary and have openings 154c that are oval.

[0045] FIGS. 12A and 12B show a catalytic converter 230 having a core 231 that includes sizing structures in the form of end caps 260. The end caps 260 define openings 261 (shown in FIG. 12B) for allowing exhaust gas to pass through the core 231. The end caps 260 have deformable tabs 263 that are compressed or bent against the outer shell of the core 231 (e.g., by a roller) to secure the end caps 260 in place. The rollers can also size and center the end caps 260. Once sized and centered, the end caps 260 can be welded to the outer casing of the core 231.

[0046] In each of the above-described embodiments, the casings of the cores define outer dimensions (e.g., dimension D1 in FIG. 2A) that are less than the corresponding outer dimensions defined by the sizing structures (e.g., outer dimensions D2 in FIG. 2A). In certain embodiments, the difference in size between the two dimensions (e.g., D1 and D2) can be less than 1 inch or less than 2 inches. Preferably, the outer dimensions of the casings are {fraction (3/16)} inch to ½ inch smaller the corresponding outer dimensions of the sizing structures. The outer dimensions of the sizing structures are preferably, but not necessarily, manufactured with a manufacturing tolerance of at most plus or minus 0.030 inches.

[0047] FIGS. 13A and 13B show a catalytic converter 330 mounted within a vertical muffler 336. The muffler 336 is preferably equipped with a water collection device 327 positioned downstream of the catalytic converter 330. The water collection device 327 can be of the type disclosed in U.S. Pat. No. 5,808,245 that is hereby incorporated by reference. The catalytic converter 330 includes a substrate 332 positioned within a can 334. The can 334 and the muffler 336 have a cylindrical shape, but could also be oval.

[0048] Referring to FIG. 13A, the can 334 includes a condensation/water capture member 337 located at the top end of the can 334. The member 337 is bent or angled relative to a central axis 339 of the converter 330. Thus, the member 337 has an axial component (i.e., a spatial component/vector parallel to the axis 339) and a radial component (i.e., a component/vector that extends perpendicular to the axis 339). The member 337 can be straight or curved. A moisture containment trough or reservoir 341 is defined between the muffler 336 and the member 337. A fluid tight seal can be provided between the can 334 and the muffler 336 to prevent water leakage between the can 334 and the muffler 336. Alternatively, a fluid tight seal is not required, and in some embodiments water can be allowed to pass between the can 334 and the muffler 336. The member 337 can be an integral part of the can 334 or can be a separate member connected (e.g., welded) to the can 334.

[0049] In use of the exhaust system, exhaust gas passes in an upward direction through the muffler 336 and the converter 330. At times, condensation may accumulate on the inner surface of the muffler 336 at a location upstream from the catalytic converter 330. It is desirable to prevent this moisture from contacting the substrate 332. The water capture member 337 prevents the condensation on the inner surface of the muffler 336 from contacting the substrate. Rather than moistening the substrate 332, the condensation accumulates in the reservoir 341. When the exhaust system heats with use, the accumulated condensation will evaporate.

[0050] FIGS. 14 and 15 show alternative embodiments having condensation capturing structures. FIG. 14 shows a catalytic converter 430 having a casing 434 that holds a substrate 432. The top end of the casing 434 includes a condensation-capturing member 437 having a radial leg 437a and an axial leg 437b. The legs 437a and 437b are depicted as being generally straight and meeting at a discrete bend location 443. Leg 437b is generally parallel relative to a longitudinal axis LA of the casing 434, and leg 437a is oblique relative to the longitudinal axis LA and angled slightly upwardly. It will be appreciated that the orientations of the legs 437a, 437b can be varied. For example, in other embodiments, the leg 437a could be perpendicular relative to the axis LA, or angled downwardly. The member 437 is adapted to define a water retention reservoir 441 when mounted in a muffler 436.

[0051] FIG. 15 shows a catalytic converter 530 having a casing 534 that holds a substrate 532. The top end of the casing 534 includes a condensation-capturing member 537 that is curled radially inwardly. The member 537 is adapted to define a water retention reservoir 541 when mounted in a muffler 536.

[0052] FIG. 16 shows a muffler system 620 including a muffler 622 and a catalytic converter 624 mounted within the muffler 622. The catalytic converter 624 includes a substrate 626 positioned within a can 628 (i.e., a casing or housing). The can 628 and the muffler 622 preferably have a cylindrical shape, but could also be oval.

[0053] Referring to FIG. 16, the can 628 includes a condensation/water capture structure 637 located at the top end of the can 628. The structure 637 includes a first portion 635 that is bent or angled relative to a central axis 639 of the converter 624. As depicted, the portion 635 is integral with the can 628 and curves from the main body of the can 628 radially inwardly toward the axis 639. The portion 635 can be straight or curved. A second portion 652 of the structure 637 is secured to the distal end of the first portion 635 (e.g., by a weld, an integral connection or other means). The second portion 652 has a cylindrical ring-like configuration and extends parallel to the muffler 622 wall as well as the wall of the main body of the can 628. A moisture containment trough or reservoir 341 is defined between the muffler 336 and the structure 337.

[0054] The reservoir 341 is preferably sized sufficiently large to hold enough condensation to prevent condensation from overflowing the reservoir and moistening the substrate 626. Preferably, the reservoir 341 as well as the other reservoirs disclosed herein has a cross-sectional area A greater than 0.0135 square inches. In some embodiments, the area A of the reservoirs is at least 0.025 inches, or at least 0.05 inches, or at least 0.075 inches, or at least 0.1 inches, or at least 0.2 inches or at least 0.3 inches. In other embodiments, the area A is in the range of 0.025-2 inch, or 0.05-1.75 inch, or 0.075-1.5 inch, or 0.1-1 inch, or 0.2-1 inch or 0.3-1 inch.

[0055] The inventive aspects of the embodiments of FIGS. 13-16 are applicable to a variety of devices having canned substrates such as diesel particulate filters or NOx traps. Further, the devices can be used in other types of shells (e.g., stand alone converter shells) other than just mufflers. Further, in the embodiments of FIGS. 13-15, the condensation containment structures are integral/unitary with the outer casings/cans. In other embodiments, the condensation containment structures could be separate baffles connected to the outer casings/cans. Moreover, the devices can be oval, round or any other shape.

[0056] The above specification and examples provide a complete description of the manufacture and use of the invention. Since many embodiments of the invention can be made without departing from the spirit and scope of the invention, the invention resides in the claims hereinafter appended.

Claims

1. An exhaust treatment apparatus comprising: a casing having first and second open ends; a substrate positioned within the casing; and sizing structures positioned at the first and second ends of the casings, the sizing structures including portions that extend radially outwardly from the casing.

2. The apparatus of claim 1, wherein the sizing structures are unitary with the casing and are bent so as to extend radially outwardly.

3. The apparatus of claim 1, wherein the sizing structures are positioned at axial end faces of the casing.

4. The apparatus of claim 1, 2 or 3, wherein the casing is oval.

5. The apparatus of claim 4, wherein the substrate is a corrugated metal substrate.

6. The apparatus of claim 1, wherein an outer shape of each sizing structure is oval, and an outer shape of the casing is round.

7. The apparatus of claim 1, wherein an outer shape of each sizing structure is round, and an outer shape of the casing is oval.

8. The apparatus of claim 1, wherein an outer shape of each sizing structure is round, and an outer shape of the casing is round.

9. The apparatus of claim 1, wherein an outer shape of each sizing structure is oval, and an outer shape of the casing is oval.

10. The apparatus of claim 1, further comprising an outer shell, wherein the sizing structures extend radially between the shell and the outer casing.

11. The apparatus of claim 10, wherein an interference fit exists between the sizing structures and the outer shell.

12. An exhaust treatment apparatus comprising: an outer shell; an open-ended casing positioned within the shell; a substrate positioned within the casing; and a water retaining structure located at one end of the casing, the water retaining structure defining a water retention space for preventing condensation on an inner surface of the outer shell from moistening the substrate.

13. The exhaust treatment apparatus of claim 12, wherein the water retention space is defined between the water retaining structure and the outer shell.

14. The apparatus of claim 12, wherein the water retaining structure includes at least a first portion that is integral with the casing.

15. The apparatus of claim 14, wherein the first portion curves radially inwardly from a main body of the casing.

16. The apparatus of claim 15, wherein the water retaining structure further comprises a second portion that extends upwardly from the first portion.

17. The apparatus of claim 16, wherein the second portion is welded to the first portion.

18. The apparatus of claim 17, wherein the second portion is a cylindrical ring that is parallel to the main body of the casing.

19. The apparatus of claim 12, wherein the casing defines a central axis, and wherein water-retaining structure includes a primarily radial portion connected to a primarily axial portion.

20. The apparatus of claim 12, wherein the water retention space has a cross-sectional area greater than 0.0135 inches.

21. The apparatus of claim 20, wherein the cross-sectional area is at least 0.05 inches.

22. The apparatus of claim 21, wherein the cross-sectional area is at least 0.1 inches.

23. The apparatus of claim 22, wherein the cross-sectional area is at least 0.3 inches.