US 3348629 A
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' Oct. 24, 1967 T. R. cAssEL V RESONATOR SILENCER Filed oct, v, 1965 1N VENTO/2. fianzas faffef ATTORNEY United States Patent C) 3,348,629 RESONATOR SILENCER Thomas R. Cassel, Birmingham, Mich., assigner to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Oct. 7, 1965, Ser. No. 493,835 Claims. (Cl. 181-48) ABSTRACT 0F THE DISCLOSURE A resonator silencer for the exhaust system of a motor vehicle wherein the tail pipe is teles'copically received within an end portion of the exhaust pipe and relatively sized to establish an annular tuning neck therebetween. A resonator shell encircles portions of the tail pipe and the exhaust pipe and has one end portion sealingly secured to the tail pipe at a point distant from the tuning neck and the other end portion sealingly secured to the exhaust pipe by removable clamping means. The resonator shell and the portion of the tail pipe that it encircles defines a tuning chamber located directly behind the tuning neck and acoustically connected to the conduit passage by the tuning neck so that the entire effort of the tuning neck is exerted on the whole mass in the tuning chamber.
The present invention provides a resonator silencer which is located coaxially with the exhaust conduit, consists of a minimum number of pieces, and utilizes the exhaust conduit itself as an integral part of the unit. In a preferred embodiment, a resonator shell is located about a smaller diameter secondary exhaust conduit and the rearward end portion of the shell is attached to the conduit. The annular space between these members forms the resonator tuning chamber or volume. The rearward end portion of the secondary conduit forms a tail spout or rearward extension of a main exhaust conduit. The forward end portion of the secondary conduit is telescopically received within an enlarged end portion of the main conduit and radially spaced therefrom to form an annular aperture therebetween which defines the tuning neck of the resonator silencer. The forward end portion of the resonator shell is sealingly secured about the outer circumference of the enlarged end portion of the main conduit to close the tuning chamber. This has the important advantage of locating the tuning neck directly ahead of the tuning chamber and thus allows the entire effort of the tuning neck to be exerted on the whole mass in the tuning chamber. This results in increased efficiency of the resonator silencer and more effective sound attenuation.
One feature of this invention is that it provides a resonator silencer which utilizes portions of an exhaust conduit as part of itsl structure.
Another feature of the invention is that it provides a resonator silencer -of improved structural rigidity and minimum shell noise.
A further feature of the invention is that the tuning neck of the resonator silencer is formed between telescoped end portions of the exhaust conduit.
Yet another feature of the invention is that it provides a resonator silencer in which the tuning neck is located directly ahead of the entire volume of the tuning chamber in the lield of sound to provide more effective attenuiation of objectionable sounds.
A still further feature of the invention is that the resonator shell of the unit is removably secured about an end portion of the exhaust conduit.
The features of the invention will be apparent from the yfollowing detailed description `and the accompanying drawings wherein:
FIGURE l is a side elevational view of portions of an internal combustion engine and exhaust system embodying a resonator silencer according to this invention; and
FIGURE 2 is an enlarged partially broken away view of a portion of FIGURE 1.
Referring to FIGURE l there is shown an intern-al combustion engine 10 having an exhaust manifold 12 to which is attached an exhaust pipe 14. The exhaust manifold and pipe for-m the forward portion of lan exhaust system 16 which also includes a conventional muer 18 attached to the exhaust pipe, a tail pipe 20 attached to the muffler, a resonator silencer 22, and a tail spout 24 through which exhaust gases from the engine exit tothe atmosphere.
As seen in FIGURE 2, the tail pipe 20 has an enlarged annular end portion 26 and the tail spout 24 has an end portion 28 of smaller diameter which is telescopically received within the end portion 26. The end portions are radially spaced from each other to form an -annular aperture 30. The pipes 20 and 24 are coaxially arranged to allow exhaust gases to iiow through the exhaust system with a minimum of back pressure. The flow areas 32 and 34 of the main portions of tail pipe 20 and tail spout 24 respectively, are substantially the same. A cylindrically shaped resonator shell 36 encir-cles a portion of the tail spout 24 and has an inwardly tapered end portion 38 terminating in a ange 40 which is wel-ded to the outer surface of spout 24. A second inwardly tapered end portion 42 of the shell terminates in :a flange 43 which is sealed and secu-red to the outer surface of end portion 26 by U-bolt 44 and saddle member 46. The Iannular space between the tail spout 24 and shell 36 defines a resonator tuning chamber 48 which is acoustically connected to the gas flow channel through the tail pipe by the annular aperture 30 which forms the tuning neck of the resonator silencer. A drain hole 50 in shell 36 provides for condensate drainage.
It can be seen that the resonator silencer is constructed so that the tuning neck is located ahead of the entire volume of the tuning chamber 48 as viewed with relation to the direction of sound wave propagation. The entire effort of the tuning neck is thus exerted on the whole mass in the tuning chamber to provide a resonator silencer of maximum efficiency.
objectionable sound waves which have their source at the engine and travel through the exhaust system `are effectively attenuated by the resonator silencer 22. The resonator silencer is tuned to the resonance frequency of the exhaust system according to well known principles by proper selection of the tuning neck conductivity and tuning chamber volume. When so tuned, the device effectively attenuates by resonance the objectionable sound waves.
A practical embodiment of the invention tuned to attenuate sound waves at a frequency of c.p.s. and constructed according to the principles of this invention has an over-al1 length, including neck and chamber, of 15.63 inches. It has been found that the improved rigidity of this resonator unit due to its specific construction and short continuous section results in minimum shell noise as compared with other conventional designs with longer continuous sections.
Thus this invention provides an improved resonator silencer.
1. A resonator silencer for attenuating objectionable sound waves comprising, a iirst conduit within which sound waves are established and having an end portion, a second conduit having an end portion thereof in smaller size than said first conduit end portion and telescopically received therewit'hin, the space between said end portions forming the tuning neck of said resonator silencer, said first and second conduits being coaxially arranged to provide a continuous and unrestrictedA passage therethrough, and a resonator shell encircling portions of said conduits and having one end thereof sealingly secured to said rst conduit end portion and the said other end thereof sealingly secured to said second conduit at a point distant from said tuning neck, said shell and the portion of the second conduit which it encircles defining the tuning chamber of said resonator silencer, said tuning chamber and the conduit passage being acoustically connected by said tuning neck.
2. The invention recited in claim 1 wherein said one end of the resonator shell is sealingly secu-red to said rst conduit end portion by removable clamping means.
3. The invention recited in lclaim 1 wherein the tuning neck is located directly ahead of the tuning chamber so that the entire effort of said tuning neck isI exerted on the whole mass in the tuning chamber.
4. The invention recited in claim 1 wherein the ow area of said second conduit is substantially the sarne as the flow area ofthe rst conduit.
5. The invention recited in claim 1 wherein the first 5 and second conduits comprise the tail pipe of an exhaust system for an internal combustion engine.
References Cited UNITED STATES PATENTS 7/1946 wils-0n 181-48 2,930,440 3/1960 Fetzer et al. 181-35 RICHARD B. WILKINSON, Primary Examiner.
15 ROBERT WARD, Assistant Examiner.