US2841237A - Muffler structure - Google Patents

Description

July 1, 1958 'G. SLAYTER 2,841,237

MUFFLER STRUCTURE Filed Dec. 14, 1953 2 Sheets-Sheet 1 y 1958 G. SLAYTER 2,841,237

MUFFLER STRUCTURE Filed D60. 14, 1953 2 Sheets-Sheet 2 INVEN TOR.

64444-29 any/2'4- United States Patent Office MUFFLER STRUCTURE Games Slayter, Newark, Ohio Application December 14, 1953, Serial No. 397,872 8 Claims. (Cl. 181-42) This invention relates to mufiiers of the type employed to dissipate the energy and thereby suppress the noise of products of combustion discharged into the atmosphere from an engine of the combustion type.

There are various different designs of mufflers available to the trade for accomplishing the above result. One

type employs bafiles arranged in the gas passage in a manacts on the engine to reduce the power output of the latter.

Another type of mufiler designed to minimize back pressure is commonly known in the trade as a straight through muffier. Generally such mufflers have a gas chamber in the form of a tube which is perforated, and is surrounded by a casing containing steel wool. In some instances the perforations are in the form of jets designed to produce a limited amount of turbulence within the muffler passage or chamber; and bafiles instead of steel wool are predeterminedly arranged in the casing surrounding the gas chamber. In either case carbon or other foreign matter eventually seals the perforations and the latter lose their effectiveness to damp or smooth out sound waves. Also both types of mulfiers are subject to considerable condensation, and must be replaced at frequent intervals.

With the above in view, it is an object of this invention to overcome the above objections by providing a muffler having a gas passage constructed to channel the flow of exhaust gases straight through the muiiler with little or no appreciable turbulence so that back pressures and consequent power losses are reduced to a negligible quantity. In accordance with this invention the walls of the gas passage are constructed to act as a diaphragm and to flex relatively freely in response to the energy of the exhaust gases flowing through the passage. Hence the sound waves are, in effect, smoothed out as the exhaust gases travel along the muffler passage, and controlled or exceptionally quiet discharge of the gases into the atmosphere results.

It is another object of this invention to provide a muftier of the above general type wherein a heat insulating material is placed in the jacket existing between the gas passage or chamber and the surrounding casing r shell. This insulation not only assists sound absorption, but in addition, minimizes condensation and its deteriorating effect on the muflier parts.

It is still another object of this invention to provide a muffler wherein the gas passage is in the form of a straight through tube having imperforate walls, so that condensate or moisture entering the tube passes through 2,841,237, Patented July 1, 1958 H the latter along with the products of combustion and cannot escape into the shell.

It is a further object of this invention to provide a mufiler possessing all of the above advantages, and at the same time, composed of a relatively few simple parts capable of being inexpensively manufactured, assembled and installed.

The foregoing as well as other objects will be made more apparent as this description proceeds, especially when considered in connection with the accompanying drawings, wherein:

Figure lis a fragmentary side elevational View of a mufiler embodying the features of this invention;

Figure 2 is an enlarged cross-sectional view taken on the line 2-2 of Figure 1;

Figure 3 is a sectional view taken on the line 33 of Figure 2;

Figure 3A is a cross-sectional View through the intake end of the muffler; I

Figure 3B is a longitudinal sectional view through a modified construction of muffier;

Figure 4 is a cross-sectional view showing another modified form of construction;

Figure 5 is a cross-sectional view of still another embodiment of the invention;

Figure 6 is a cross-sectional view of a further modified form of mufiier construction;

Figure 7 is a longitudinal sectional view of still another modification;

Figure 8 is a cross-sectional view taken on the line 8-8 of Figure 7;

Figure 9 is an enlarged fragmentary sectional view of the construction shown in Figure 7; and

Figure 10 is a cross-sectional view taken on the line 10-10 of Figure 7.

The muffler shown in Figures 1 to 3 inclusive comprises an outer shell 10, a tube 11 extending axially through the shell, and insulating material 12 housed in the space 16 provided between the tube 11 and shell. The shell 10 may be formed of sheet metal or any suitable material, and has end walls 13 welded or otherwise secured to opposite ends of the shell.

The tube 11 is also preferably formed of sheet metal, and is fashioned to the cross sectional contour shown in Figure 2 of the drawings. In detail, the walls of the tube have corrugations which extend parallel to one another for substantially the full length of the tube, and which are shaped to provide a multiplicity of circumferentially spaced individual chambers 14. Each chamber 14 is of substantial cross-sectional area and has converging side walls providing a restricted slot or passage 16 communicating with the passage 15 throughout substantially the full length of the passage 15. As shown in Figures 3 and 3A of the drawings, the opposite side walls of each chamber are bent toward one another at the re ceiving end of the tube 11 and are brazed or welded together. The exhaust gases are introduced into the receiving end of the tube 11 by a pipe A telescoped within the tube 11 and Welded or otherwise secured to the tube 11. The discharge end of the tube 11 projects beyond the adjacent end of the shell 10 and the corresponding ends of the chambers 14 are open. Special care is taken to seal the space 16 against the escape of exhaust gases into this space. In order to assure preventing the escape of exhaust gases into the space 16 at the receiving end, the adjacent end wall 13 may he brazed to the ends of the corrugations throughout their length. At the delivery end the wall 13 may be notched to receive the terially reduced. Moreover, the opposite side walls of the corrugations are substantially straight and the gage of the metal forming the said walls is selected so that the entire wall of the tube 11 is free to flex and provide a diaphragm action in response to sound vibrations of the exhaust gases.

Hence, the sound waves are transmitted to the sound insulating material 12 and are substantially absorbed by this material.

As stated above the chambers 14 are open at the discharge end of the tube 11 so that exhaust gases entering the chambers are in eifect channeled straight through the chambers to the tail pipe B. This construction has the effect of reducing turbulence of the exhaust gases passing through the muffler and, as a consequence, also reduces to a minimum any tendency for back pressures to develop within the muffler. In addition moisture usually present in the exhaust gases entering the tube 11 is carried straight through the muffler with the exhaust gases and is prevented from accumulating within the chambers 14. It is also important to note that the wall of the tube 11 is imperforate and, hence, there is no opportunity for moisture to escape from the tube 11 into the outer shell 10 of the muffler. This feature reduces the tendv ency for the muflier to rust-out and prolongs the effective life of the mufller.

The internal diameter of the shell and the overall outside diameter of the tube 11 are predetermined to afford a generous annular space 16' within the shell in around the tube 11. This space accommodates the insulating material 12 which may be rock wool, or some equivalent sound deadening material. Such a material not only contributes to the sound absorbing characteristics of the muflier, but in addition, reduces condensation within the shell 10 to a minimum. In this connection it is apparent that the temperature of the tube 11 increases at a rate much faster than the shell 1t}; and unless provision is made for insulating the tube 11 from the shell 1i considerable moisture may accumulate within the shell. This condition is aggravated in instances where the muffler is subjected to infrequent use for short periods, and is overcome by the present invention.

In some instances it may be advantageous to also seal or close the discharge ends of the chambers 14. This may be accomplished by pressing the opposite walls of each chamber 14 together at the delivery end of the tube 11, and by welding or brazing the joints between these walls in the same manner noted in Figure 3A. Such a construction is shown in Figure 3B and it will be noted that the tail pipe C is telescoped into the delivery end of the tube 11 and is welded, brazed or otherwise secured in place similar to the intake pipe A. In this embodiment the chambers 14 act solely as expansion chambers for the exhaust gases flowing through the passage 15, and the efliciency of these chambers to absorb sound is somewhat increased. Also in the embodiment shown in Figure 3B it will be noted that both end walls 13' are the same and are brazed to the opposite ends of the corrugations to effectively seal the space 16 against the escape of exhaust gases into the same.

The features of this invention may also be accomplished with tubes of numerous different shapes. For example in Figure 4 of the drawings a mufller is shown which is elliptical in cross section. The mufller has an outer shell 17, an inner shell or tube '18 and heat insulating material 19. The tube 18 forms a straight through passage for exhaust gases and the walls 20 may be fashioned with corrugations 21 which extend lengthwise of the tube i parallel relation to the axis of the latter to provide expansion chambers. In any case the walls 20 are of a nature to flex when subjected to stresses of the order applied to the walls by the exhaust gases flowing through the tube. The shell 17 is sufliciently larger than the tube 18 to afford a space 22 therebetween for accommodating the heat insulation 19 which may be rock wool, or some equivalent material.

In Figure 5, of the drawings, a muflier 23 is shown as having an outer cylindrical shell 24, an inner shell or tube 25 extending axially through the outer shell, and insulating material 26 housed within the space between the shells. The inner shell or tubeZS comprises two substantially semi-cylindrical half sections 27 having marginal edge portions arranged in overlapping engagement. The opposite ends of the half sections are welded or otherwise secured together to provide a unitary construction. The portions of the half sections 27 between the secured ends move relative to one another in response to the flow of exhaust gases through the tube 25, and hence dissipate the energy as well as the sound of the exhaust gases passing through the tube.

In Figure 6 of the drawings a muflier similar to the one shown in Figure 5 is shown, except that the tube 28 forming the gas passage is made up of a series of arcuate sections 29. One marginal edge of each arcuate section 29 has a radially outwardly extending flange 3t) and the opposite marginal edge has an inwardly opening return bent portion 31. The return bent portion 31 of one section receives the flange 3% on an adjacent section in a manner such that the sections cooperate to form the tube 28. The opposite ends of adjacent sections are preferably secured together by welding, brazing or by some other acceptable means of attachment. In any case the portions of the sections between the ends may move rela .tive to one another, and in this manner, dissipate the energy as Well as the sound of the exhaust gases flowing through the nibe.

In exceptionally high temperature installations, it may be desirable to use a mufiier of the general type shown in Figures 7 to 10 of the drawings. This muifler is similar in construction to the one shown in Figures 1 to 3 inclusive and corresponding parts are indicated by the same reference numerals. The muffler featured in Figure 7, however, has an intake conduit 32 which extends into the entrant end of the tube 13 and has an outside diameter smaller than the internal diameter -of the main gas passage 15 to provide an annular passage 33. The passage 33 communicates with the atmosphere at the entrant end of the gas passage 15 so that airis induced to flow into the gas passage 15 by the flow of exhaust gases through the passage 15. The passage of induced air through the passage 15 along with the exhaust gases has a cooling effect on the muffler, which is highly advantageous in installations where abnormal temperatures are encountered.

In each of the above embodiments, the products of combustion, together with any moisture, pass straight through the muffler with little or no appreciable turbulence. Also the walls of the gas passage act as a diaphragm to effectively absorb or smooth out the sound waves, and in addition, heat insulation is provided to minimize accumulation of moisture within the outer shell of the muflier. Thus according to this invention exhaust gases are discharged into the atmosphere without objectionable noise,- and with negligible back pressure by a tion of moisture.

What I claim as my invention is:

1. A muflier comprising an elongated chamber having a gas coniiining imperforate wall defining a. straight through passage from one end of the chamber to the other for exhaust gases and having circumferentially spaced corrugations extending lengthwise of the passage, said corrugations opening intothe passage to form expansion chambers for the exhaust gases and cooperating to impart suflicient flexibility to the wall to permit flexing of said wall in response to the stresses applied to the wall by the exhaust gases.

2. The structure defined in claim 1 comprising a shell surrounding the gas confining wall in spaced relationship thereto, and insulating material housed within the space provided between the gas confining wall and shell.

3. The structure defined in claim 1 wherein opposite side walls of the corrugations converge in an inward direction toward the straight through passage and provide openings of restricted width between the inner ends of of adjacent corrugations through which exhaust gases flow from the straight through passage into the respective corrugations.

4. The structure defined in claim 3 wherein the extremities of the corrugations at the receiving end of the straight through passage are closed to compel the exhaust gases to flow into the expansion chambers through said restricted openings.

5. The structure defined in claim 4 wherein the corrugations extend for substantially the full length of the straight through passage and wherein the gage of the walls of the corrugations is predetermined to provide a diaphragm action in response to the energy contained in the exhaust gases admitted to the straight through passage.

6. A muffler comprising an elongated chamber having a gas confining wall defining a straight through passage from one end of the chamber to the other for exhaust gases and having circumferentially spaced corrugations extending lengthwise of the passage, said corrugations opening into the passage to form expansion chambers and having the opposite side walls converging inwardly toward the straight through passage providing each expansion chamber with a restricted entrant opening of a width substantially less than the width of the associated expansion chamber, the walls of the corrugations being of a gage predetermined to permit flexing of the gas confining wall in response to the energy of the exhaust gases admitted to the elongated chamber.

7. The structure defined in claim 6 wherein the walls of the corrugations are imperforate and wherein the radially inner ends of adjacent corrugations cooperate to form a central uninterrupted passage through the elongated chamber.

8. A muflier comprising an elongated chamber having a gas confining wall defining a straight through passage from one end of the chamber to the other for exhaust gases and having circumferentially spaced corrugations extending lengthwise of the passage, said corrugations opening into the passage to form separate expansion chambers and having the opposite side walls converging inwardly toward the straight through passage providing each expansion chamber with a restricted entrant opening of a width substantially less than the width of the associated expansion chamber.

References Cited in the file of this patent UNITED STATES PATENTS 781,939 Fulton Feb. 7, 1905 2,248,456 Harris July 8, 1941 2,292,340 McCurdy Aug. 4, 1942 2,508,463 May May 23, 1950 2,528,674 Thomas Nov. 7, 1950 2,718,273 Dehaus Sept. 20, 1955 FOREIGN PATENTS 316,082 Germany Nov. 20, 1919

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