US3223491A - Muffler construction - Google Patents

Description

Dec. 14, 1965 J. B. MAlLLlE ETAL 3,223,491

MUFFLER CONSTRUCTION Filed Sept. 27. 1962 4 Sheets-Sheet 1 FIG.|

FlG. 4 W 23 67 Dec. 14, 1 J. B. MAlLLlE ETAL MUFFLER CONSTRUCTION 4 Sheets-Sheet 2 Filed Sept. 27, 1962 1965 J. B. MAILLIE ETAL 3,223,491

MUFFLER CONSTRUCTION 4 Sheets-Sheet 3 Filed Sept. 27, 1962 F|G.7 4a 4 23 V /1 \m [7i E I United States Patent Ohio, a corporation of Ohio Filed Sept. 27, 1962, Ser. No. 226,709 2 Claims. (Cl. 23--288) The invention relates generally to catalytic apparatus for eliminating obnoxious vehicle exhaust emissions by oxidation, and more particularly to a catalytic apparatus adapted for connection to the exhaust pipe of an internal combustion engine to replace the conventional mufiier, thus eliminating noise as well as fumes.

Catalytic muffiers have a number of requirements, which makes the construction of a practical, etficient and economical muffler for this purpose a difllcult and complicated problem. The mufller shell must be of practical and reasonable dimensions, must not create excessive back pressure on the engine, must provide properly distributed contact between the exhaust gases and the catalytic material, must be rugged to withstand mechanical shocks in use and minimize distortion, and must provide for differential expansion between the outer parts and the inner parts where high temperatures are generated due to oxidation.

In addition, problems arise because the catalytic material is preferably in the form of granules or pellets, and must be supported in a relatively thin layer or bed, preferably in slightly tilted, substantially horizontal position, in such manner as to avoid excessive pressure drop and gas leakage in normal operation, while providing for positive by-passing of the bed by the gases in case of abnormal situations, such as fouled spark plugs, which would create excessive bed temperatures, damaging the catalyst as well as the muflier.

The temperatures required for catalytic oxidation of vehicle emissions are upwards of 1000 F., necessitating the use of stainless steel parts, at least in and adjacent to the catalytic bed, but even such high-temperature alloys require substantial intermediate support to prevent sagging and distortion, and there is the ever-present problem of compensating for differential expansion without excessive use of costly metal.

Certain prior catalytic mufflers have been proposed which meet a substantial number of the foregoing requirements, but said prior constructions have been diflicult and expensive to fabricate, involving laborious hand operations, uneconomic use of stainless steel, and an excessive number of parts. They have also inhibited the free spread of catalytic action and created turbulence in the flow of exhaust gases therethrough.

A general object of the present invention is to provide a novel and improved catalytic muffler construction which will meet the foregoing requirements, which will be more efficient in operation, and which can be simply and economically fabricated with a minimum of material and labor.

Specifically, an object of the present invention is to provide a catalytic mufiler construction which utilizes a minimum number of parts and lends itself to fabrication by automatic welding operations.

Another object is to provide an improved construction for solidly supporting the catalytic bed while minimizing distortion and compensating for differential expansion of the parts thereof relative to the muflier shell.

A further object is to provide an improved light-weight central beam construction for preventing sagging while permitting free spread of catalytic action throughout the bed.

3,223,491 Patented Dec. 14, 1965 Another object is to provide an improved deflector valve arrangement for selectively by-passing flow of exhaust gases around the bed.

A further object is to provide an improved mufller construction for facilitating easy replacement of the catalytic material in the bed.

A still further object is to provide an improved mufller construction which promotes smooth, non-turbulent flow of exhaust gases to and from the catalytic bed.

These and other objects are accomplished by the parts, constructions and combinations comprising the present invention, a preferred embodiment of which is shown in the drawings and described herein as an example of the best known mode of carrying out the invention. Various modifications and changes in details of construction are embraced within the scope of the appended claims.

The improved catalytic muffler comprising the present invention consists of a flattened tubular one-piece body shell surrounding a rectangular construction of channels and perforate grids containing a bed of catalytic material, the bed structure being spaced from the top and bottom of the body shell to form gas inlet and discharge ducts. Central longitudinal embossments formed inwardly top and bottom in the body shell are welded to an open, nonwarpable, bed-supporting beam in the bed structure in such manner as to permit differential expansion between the shell, the beam and the bed structure. The perforate grids of the bed structure are slidably supported both peripherally and along the longitudinal beam. Inlet and outlet end shells, attached to the body shell by welded mating peripheral flanges, provide smooth, non-turbulent gas flow to and from the bed. The mated flanges provide positive location for a wrap-around thermal insulation blanket and means for attaching its protective cover. A simplified deflector valve is mounted in the inlet end shell for selectively by-passing flow of exhaust gases around the bed.

Referring to the drawings:

FIG. 1 is a plan view of a catalytic muflier embodying the present invention.

FIG. 2 is a side elevation thereof.

FIG. 3 is a front end elevation thereof.

F IG. 4 is a rear end elevation thereof.

FIG. 5 is an enlarged longitudinal sectional view, parts being broken away.

FIG. 6 is a cross sectional view on line 66 of FIG. 5.

FIG. 7 is a further enlarged view of a portion of FIG. 5.

FIG. 8 is an enlarged view of a portion of FIG. 2 partly broken away and in section.

FIG. 9 is a fragmentary enlarged plan sectional view of the inlet portion of the mufiier, with parts broken away.

FIG. 10 is an elevation on line 1010 of FIG. 5, of the by-pass deflector valve removed from the muffler.

FIG. 11 is a transverse sectional view on line 11-11 of FIG. 9, with parts removed.

FIG. 12 is a fragmentary sectional view of the filler tube in the rear end.

FIG. 13 is a detached fragmentary perspective View of the expansible bearing strip between the grids and the central beam.

Referring first to FIGS. l4, the improved catalytic mufiler comprises a flattened elongated body 20, substan-' tially rectangular in all elevations and having tapered end shells 21 and 23 attached to its inlet and outlet ends, respectively. Inlet end shell 21 preferably has a usual attaching flange 22 for bolting to a similar flange on the exhaust pipe (not shown) of an internal combustion engine. Outlet end shell 23 is attached to the other end of the body 20 and preferably terminates in a cylindrical exhaust pipe 25.

3 As shown in FIGS. 5 and 6, the body 20 comprises an inner bed structure including spaced-apart upper and lower grids 26 and 27 with a central longitudinal beam ,or web 28 extending vertically between the grids, a body shell 29 surrounding said bed in vertically spaced relation to said grids, and ametal cover 30 enclosing a blanket 31 of thermal insulation material wrapped around the body shell 29.

The upper and lower grids are foraminous plates; that is, they have a multiplicity of openings or perforations formed in the plates in any suitable manner. The openings are large enough to permit through flow of gases but small enough to prevent escape of the catalyst granules.

The body shell 29 is preferably a single piece of sheet metal, which is formed into a flat tubular shape and seamwelded at any convenient location (not shown). The body shell is vertically spaced above grid 26 and below grid 27 to form gas inlet and outlet ducts 38 and 39, respectively. Preferably, the grids 26 and 27 are inclined slightly with respect to the top and bottom portions of the shell, so that the duct 38 is relatively deep at its inlet end 38A and relatively shallow at its opposite end 38B, while duct 39 is relatively shallow at the inlet end 39A and relatively deep at the opposite or outlet end 39B. Exhaust gases normally enter inlet end 38A, and due to the inclination of the bed are more effectively and uniformly directed into and through the bed.

The upper portion of body shell 29 has a central longitudinal embossment or channel 40 formed inwardly thereof, and the lower portion of body shell 29 has a central longitudinal embossment or channel 41 formed inwardly thereof. The inward faces of embossments 40 and 41 intermediate their ends rest against the upper and lower grids 26 and 27, respectively, and the end portions 40A, 40B and 41A, 41B of the embossments taper outwardly and terminate at the peripheral flanges 42 and 43 which extend continuously around the inlet and outlet ends, respectively, of the body shell 29. The intermediate portions of embossments 40 and 41 vary in depth to accommodate the inclination of the grids 26 and 27 with respect to the body shell 29.

The novel one-piece body shell with outwardly flanged ends eliminates peripheral trim waste and gas port punchout waste inherent in prior constructions using deep drawn half shells, and eliminates expensive welding entirely around the outer periphery of the mufller by requiring welding only one longitudinal seam. Moreover, the improved one-piece shell provides for positive attachment of the insulation cover locating the insulation blanket, and for cam-programmed automatic welding of the shell to the end shells.

The central beam or web 28 is preferably substantially co-extensive with the intermediate portions of embossments 40 and 41 and terminates adjacent to the start of the tapered end portions, so that longitudinal expansion and contraction of the beam is minimized while providing adequate support for the grids 26 and 27. Large openings 44 are provided through the beam at longitudinal intervals between welds attaching the beam to the body shell 29. These openings serve to provide communication between both sides of the bed to permit spread of catalytic action throughout the bed, as well as to facilitate rapid filling and removing of catalytic material. Further, the openings 44 Weaken the web between weldments and provide for incremental take-up of the Webs longitudinal expansion by slight lateral bending of the weakened portions. The beam 28 being fore-shortened at both ends substantially reduces the amount of stainless steel required for central support in previous designs.

Longitudinally expansible bearing strips 45 are preferably interposed between the edges of perforated center beam 28 and the inner surfaces of grids 26 and 27, for the purpose of providing continuous support to same. As shown in FIGS. 5, 6, 7 and 13, these strips have longitudinal slots 46 at longitudinal intervals through which projections 47 on the beam 28 extend. The projections 47 continue into further stepped projections 48 which extend through accommodating longitudinal slots 49 in the intermediate bottom portions of embossments and 41 and are attached thereto. The projections 47 also project through the grids 26 and 27 (FIG. 7), via longitudinal slots which are long enough to permit differential expansion movement between the beam and the grids. The shoulders formed between projections 47 and stepped projections 48 locate and support the body shell embossments 40 and 41 during assembly.

Between the slots 46 the bearing strips are provided with staggered transverse edge-opening slots 51A and 51B, which take up the strips longitudinal expansion movements incrementally between beam projections 47. The bearing strips 45 widen the continuous bearing area between the beam edges and the grids to prevent sagging, and also prevent catalyst granules from working their way into the ends of grid slots where they would be subject to crushing due to differential expansion. Thus, the grids are free to move longitudinally and the differential longitudinal expansion between the cool body shell and the hot beam-and-bearing-strip structure is divided into a plurality of small harmless increments.

The insulation cover 30 is preferably an aluminum sheet wrapped around the body shell 29 in spaced relation to enclose the thermal insulating blanket 31 engirdling the body shell 29. The cover 30 is preferably lock-seamed at any convenient location (not shown), and its ends are formed into inward peripheral flanges 52 and 53 for locking engagement with the shell flanges. The cover 30 thus secures the insulation blanket 31 on the mufller and seals its ends against road splash.

The side edges of grids 26 and 27 are slidably received in longitudinal slots formed between the legs 55 and 56 of nested channels 57 and 58 extending longitudinally along the side wall portions 59 of body shell 29. The inner channels 57 are welded at longitudinal intervals to the outer channels 58 and the webs of the inner channels are provided with openings 60 between weldments, so that the nested channel assemblies can be attached to the side wall portions 59 by spot welding the outer channels to the shell through the openings 60. This avoids the difliculties of welding through three thicknesses of metal.

The end edges of grids 26 and 27 are similarly received in transversely extending slots formed between the legs 55" and 56' of nested channels 57' and 58' extending transversely of the ends of the grids and closed at their ends against the ends of side channels 57 and 58. The Webs of inner channels 57' are provided with welding openings 60' through which the outer channels 58' can be spot welded to the end shells 21 and 23, respectively. As seen in FIG. 5, the channel 58' at the outlet end is welded to the upper flat portion of outlet end shell 23; and the channel 58 at the inlet end is welded in its laterally central portion to the vertical flange 62 of inclined partition 63 in the inlet end shell 21, and welded near its ends to inward projections of flange 64 of inlet end shell 21, as seen in FIG. 11.

The inlet end shell 21 tapers outwardly from the circular opening 22' in its attaching flange 22 to flat substantially rectangular shapes top and bottom, as shown in FIG. 11, and it terminates in a peripheral flange 64 mating with peripheral flange 42 on body shell 29. Preferably, flanges 42 and 64 are welded together by an automatic welding operation.

As seen in FIGS. 9 and 11, the flat outward tapers of inlet shell 21 form lateral transition chambers which communicate with upper and lower gas ducts 68 and 69, and they are separated by a central chamber formed substantially by vertical side walls 66 and 67. The transition chambers are smoothly tapered to avoid the turbulence created in many prior designs, with resultant increase in back pressure. Moreover, less material and labor and a minimum of welding (all automatic) is required. The

inclined partition 63 extends laterally between the walls 66 and 67, and its laterally curved lower edge 70 conforms to and is through-welded against a curved inset 71 formed jaw-fashion in the lower portion of inlet shell 21. The upper portion of partition 63 is bent rearwardly downward to form the transverse attaching flange 62, thus completing the sealed separation of flow chambers communicating with upper and lower gas ducts 68 and 69.

The partition 63 has a preferably circular valve port 72 formed centrally therein, and a substantially semicircular deflector valve 73 is provided with a spherically shaped embossment 73 which normally seats in valve port 72, as shown in FIG. 5, closing off the entrance of gas flow to the lower transition chamber and the lower gas duct 39A. The deflector valve 73 is pivotally mounted from its underside on a shaft 74 by means of an arm 75 attached to a center post 76 in the spherically embossed portion of the valve, for swinging to the dotted line position. The shaft 74 is journaled at its inner end in a bearing 77 formed in a bracket 78 attached to flange 62, and the shaft extends through a gas-tight bearing 79 in side wall 66.

The outer end of shaft 74 has a lever arm 80 thereon which is pivoted at its outer end by a pin and slot connection 81 (FIG. 8) to the operating arm 82 connected to the diaphragm of a conventional vacuum booster 83 mounted on a bracket 84 attached to the flange 64 of inlet end shell 21. The arm 82 normally holds the lever 80 in the full line position of FIGS. 5 and 8 to hold deflector valve 73 closed, and it swings to the dotted line position to direct the gas flow on a bypass course around the catalyst when necessary to prevent over-heating.

The improved one-piece deflector valve utilizes a minimum of material, and the location of its pivotal mounting on the underside eliminates any obstacles to normal gas flow. The interior bearing 77 reduces the number of exterior wall gas-tight bearings to one instead of two, as in many prior constructions.

The by-pass system is preferably controlled by the temperature of the catalytic material in the bed between the grids 26 and 27. As shown in FIG. 1, a thermocouple probe 86 may be inserted through the upper flat portion of outlet end shell 23, extending into the central portion of the catalytic bed. The thermocouple 86 is calibrated to actuate a thermal switch 87 at a predetermined maximum temperature above which the bed structure or the catalytic material or both would be damaged. The switch 87 is electrically connected to activate the vacuum booster during normal operation of the muflier. When high temperatures threaten, the switch shuts off the vacuum and permits the usual diaphragm-opposing spring in the booster to open the by-pass valve.

The flat portion 23 of the outlet end shell is readily adapted to accommodate a filling tube 92 extending through rear channels 57 and 58' and opening direcfly into the space between grids 26 and 27 for filling or replacing catalytic material forming the bed. A suitable cap 93 normally closes the tube. Thus, the filler opening, as Well as the thermocouple opening, is directly accessible to the catalytic bed rather than through the thermal insulation blanket and cover which are required when inserted from the side of the mufller.

The location of the thermal switch and filler tube at the rear end of the muflier above the transition chamber 24 of the outlet end shell protects them from road damage from flying stones and the like, and it also simplifies packaging or palletizing the mufflers for shipment.

The transition chambers 21 and 24 of the inlet and outlet end shells provide smooth, gradual transition of gas flow from the exhaust pipe opening 22' into the upper gas duct 38 (or via 21' into the lower gas duct 39 during by-pass), and from the lower gas duct 39 to the tail pipe 25, without requiring punched out gas flow openings in the body shell, the ragged edges of which tend to create turbulence in the gas flow.

In the operation of the improved catalytic muflier, the exhaust gases entering the inlet end shell 21 flow through port 22' and are deflected upwardly by the deflector valve 73 in its normal closed position into the entrance end 38A of upper gas duct 38. The hot gases flow uniformly over the entire upper surface of inclined upper grid 26 and pass through the openings 35 therein into and through the bed of catalytic material contained between grids 26 and 27. The catalytic material causes oxidation of noxious exhaust emissions, resulting in temperatures of the order of 1000-1400 F. The gaseous products ofcombustion flow through lower grid 27 into the lower gas duct 39, and thence out through the transition chamber 24 of outlet end shell 23 and exhaust pipe 25.

The construction of the improved catalytic mufller is such as to reduce or muflle the sound of the exhaust from the engine, so that it performs the dual function of reducing noise and eliminating fumes.

If the temperature of the bed is unduly elevated by excess hydrocarbons in the exhaust gases, e.g., caused by a fouled spark plug or carburetor malfunction, the thermocouple will actuate the switch 87 to cut off the vacuum and permit the diaphragm-opposing spring (not shown) to move deflector valve 73 to its upper position, closing the upper transition chamber to gas duct 38 and opening the lower transition chamber to gas duct 39 to the direct flow of exhaust gases, thus by-passing the catalytic bed. As soon as the bed temperature returns to normal, the thermocouple actuates switch 87 to reinstate the vacuum and the vacuum booster diaphragm movement returns the deflector valve to normal position, deflecting flow into upper gas duct 38.

The improved catalytic mufller is simple and inexpensive to fabricate and service, embodies a minimum number of parts and a minimum quantity of material, and it minimizes distortion and sagging due to high operating temperatures. It also provides smooth flow transitions and minimizes back pressures due to turbulence. Moreover, it effectively removes noxious exhaust emissions and eliminates engine exhaust noise, while providing compact and rugged construction highly resistant to shocks and impact.

What is claimed is:

1. Catalytic muffler construction for exhaust gases comprising, upper and lower foraminous grids having spaced longitudinal slots and forming an elongated flattened bed structure for enclosing catalyst material, a one-piece body shell surrounding said upper and lower grids and having peripheral flanges at either end, longitudinal inward embossments formed in said body shell exteriorly of said grids, a longitudinal perforated center beam between said grids extending a portion of the length thereof, spaced projections on the edges of said longitudinal perforate beam extending through said spaced slots in said grids and attached to said longitudinal inward embossments of said body shell, bearing strips interposed between said longitudinal center beam and the inner surfaces of said grids, whereby said grids are movably supported and the catalytic material is restricted from escaping into the slots of said grids, end shells having peripheral flanges mating with and attached to the peripheral flanges on said body shell and providing tapered flow transitions, and means on the interior of said body shell and end shells sealing the periphery of said grids against the escape of catalyst material.

2. Catalytic muflier construction in accordance with claim 1 wherein said means on the interior of said body shell and end shells sealing the periphery of said grids against the escape of catalyst material comprises nested channels which matingly engage the peripheral edges of said upper and lower grids.

(References on following page) 7 References Cited by the Examiner 3,024,593 UNITED STATES PATENTS ggggggi 8/1926 Cornelier 23288 0 6 39 11/1949 Sills. 5 3 090: 7; 1/1957 Houdry 232 8 3 094 394 10/ 1957 Bratton. 3 097 074 5/1958 Houdry 23288 9/1958 Karol et a1. 23288 8/1959 Houdry et a1 23288 10 448,850 10/1959 Houdry 23288 7/1961 Claussen 23288 3/ 1962 Houdry.

8/ 1962 Eastwood.

3/1963 Raymond 23288 4/1963 Bloch 23288 XR 5/1963 Scheitlin et a1 23288 6/1963 Innes et a1. 231288 7/1963 Johnson 23288 FOREIGN PATENTS 6/ 1936 Great Britain.

MORRIS O. WOLK, Primary Examiner.

Claims (1)

1. CATALYTIC MUFFLER CONSTRUCTION FOR EXHAUST GASES COMPRISING, UPPER AND LOWER FORAMINOUS GRIDS HAVING SPACED LONGITUDINAL SLOTS AND FORMING AN ELONGATED FLATTENED BED STRUCTURE FOR ENCLOSING CATALYST MATERIAL, A ONE-PIECE BODY SHELL SURROUNDING SAID UPPER AND LOWER GRIDS AND HAVING PERIPHERAL FLANGES AT EITHER END, LONGITUDINAL INWARD EMBOSSMENTS FORMED IN SAID BODY SHELL EXTERIORLY OF SAID GRIDS, A LONGITUDINAL PERFORATED CENTER BEAM BETWEEN SAID GRIDS, A LONGITUDINAL PERFORATED CENTER BEAM BETWEEN SAID GRIDS EXTENDING A PORTION OF THE LENGTH THEREOF, SPACED PROJECTIONS ON THE EDGES OF SAID LONGITUDINAL PERFORATE BEAM EXTENDING THROUGH SAID SPACED SLOTS IN SAID GRIDS AND ATTACHED TO SAID LONGITUDINAL INWARD EMBOSSMENTS OF SAID BODY SHELL, BEARING STRIPS INBTERPOSED BETWEEN SAID LONGITUDINAL CENTER BEAM AND THE INNER SURFACES OF SAID GRIDS, WHEREBY SAID GRIDS ARE MOVABLY SUPPORTED AND THE CATALYTIC MATERIAL IS RESTRICTED FROM ESCAPING INTO THE SLOTS OF SAID GRIDS, END SHELLS HAVING PERIPHERAL FLANGES MATING WITH AND ATTACHED TO THE PERIPHERAL FLANGES MATING WITH AND ATTACHED TO THE PERIPHERAL FLANGES ON SAID BODY SHELL AND PROVIDING TAPERED FLOW TRANSITIONS, AND MEANS ON THE INTERIOR OF SAID BODY SHELL AND END SHELLS SEALING THE PERIPHERY OF SAID GRIDS AGAINST THE ESCAPE OF CATALYST MATERIAL.

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