US2942684A - Muffler - Google Patents

Description

Jim 28, 1960 P. K. BENNETT 2,942,684

MUFFLER Filed Dec. 25. 1957 INVENTOR.

I F|G- 3 I PORTER K B ENNE BY p 2 A'TTORNE United States Patent MUFFLER Porter K. Bennett, Cortland, N.Y., assignor to Champion Sheet Metal Company, Inc., Cortland, N.Y., a corporation of New York Filed Dec. 23, 1957, Ser. No. 704,749

4 Claims. (Cl. 181-58) This invention relates to mufflers, and more particularly, to a muffier for an internal combustion engine. The invention also relates to an improved method for mufiiingv the exhaust gases from an internal combustion engine. 1

In the past, several concepts of vertical or cyclone type muflling devices have been contemplated. However, each modification has been limited in its application due either to the structure, or to the method by which it conveys,

exhaust gases .to the atmosphere. Types have been developed which were limited in that they could be placed only immediately adjacent the exhaust port of the engine, or were limited to a two-cycle engine. Others were provided with rotating parts, bafiies, complicated chambers, orrestrictions in the flow path of the gases. Others have been provided for railroad engines, or for shipboard engines in which a spark and clinker arresting pit has been provided. All of these types cause a considerable loss of engine efficiency due to excessive turbulence oi the gases within the muffler, or due to exhaust back pressure in excess amounts. With some types, the engine will perform efliciently at high, or low, or intermediate speeds, but not at others. Some will cause inefiiciency when the engine is or is not laboring, but not underv both conditions. The use of baffies in prior mufliers impedes the flow of exhaust gases to some extent, and causes excessive turbulence in the path of flow. Further, since the bafiies are not exposed to the atmosphere, they are not adapted to cool evenly and transport heat away from the mufiier. Thus, they become corrosion traps, causing the muffier to become burned out too quickly.

It is therefore a leading object of this invention to provide a mufiler which is adapted to contribute to the efiiciency of an engine.

It is also a leading object of this invention to provide a mufiler which is inherently simple in construction and which is adapted to provide limited control of the turbulence of exhaust gases within the muffler.

It is a further object to provide a mufiler which does not hinder the operation of an engine whether the engine is idling, cruising, or laboring; or when the engine is operating at low, intermediate, or high speeds.

Another objectof this invention is to provide a mufiler which, due to its inherent simplicity, is of low cost to manufacture, is easily installed, and is adapted for long operative life.

In accordance with the above, a mufiier is provided having an inlet and an outlet in a substantially cylindrical casing. Exhaust gases received from the engine are adapted to make at least one revolution around the interior of the casing before being exhausted into the atmosphere. .The mufiier is adapted for use with any engine from which a volume of exhaust gas is conveyed to the atmosphere, and where it is of any importance that noise be reduced, back pressure he equalized; and in so doing, not binder in any way the operation of the engine under any condition. The method by which this is ac complished is to revolve the volume of gas constantly in a. drum, so that a limited turbulence occurs at the central portion of the drum. This turbulence cushions the pulsations of the entering gases, and the overall rotations of the gas tends to reduce the velocity of the gas. The incoming gas expands and partially mixes with the outgoing gas, thus reducing noise, and equalizing back pressure.

The above, and further advantages of this invention will become apparent from the following specification when taken with reference to the accompanying drawing, in which:

Figure 1 is a perspective view of the invention.

Figure 2 is a side elevation of the invention.

Figure 3 is a plan view of the invention in section, taken along line 3-3 of Figure 2.

Figure 4 is an end view of the invention.

Figure 5 is an enlarged sectional view of a portion of the invention as taken along line 55 in Figure 2.

The muffler comprises an unbaflled expansion chamber substantially cylindrical in form having a cylindrical side 11 and a pair of heads 10. Each head 10 is flanged around its outer periphery, so that the flange 21, Figure 5, stands at substantially right angles with the main portion of the head 10. The head 10 is then placed in the edge of the cylindrical side 11, so that the side of flange 21 lies adjacent the edge of the side 11, and a weld 20 is formed around the entire periphery of the drum. Before assembly, the sides of the heads are dished or drummed out slightly, as in Figures 3 and 4. Then, as the heads 10 are being welded in place, heat from they welding draws out the convex surface so that the head is nearly fiat after assembly. This causes a tensioning of the heads 10, and obviates drumming of the muffler, as will be explained in greater detail.

An inlet pipe 12 enters the side 11 of the muffler at any point 17, and is disposed tangentially thereto. The end of the inlet 12 which is located inside the mufiier is disposed at a point just beyond an imaginary radius 18, Figure 2, drawn perpendicular to the inlet pipe 12. A similar outlet pipe 13 is disposed through the side 11 of the muffler at a point 17 therethrough. The outlet pipe is disposed to one side of the inlet 12, and in a direction parallel to the inlet. The outlet 13 is also tangent to the side of the mufiier, as is the inlet 12. The inner end of the outlet 13 also lies just beyond the imaginary radius 18. Thus the ends of the outlet 13 and inlet 12 overlap each other. A tack weld 14 between the two pipes, at their inner ends prevents any sympathetic resonance or other vibration which would cause a noise in the mufiier. At the point where the two pipes enter the shell or side 11 of the muffler, the pipes are welded in an airtight fastening to the side 11.

Operation The mufiler is adapted to be mounted in any position to the vehicle on which is mounted the engine (not shown). Thus the mufiler will perform at the highest efficiency with the inlet and outlet at the top or bottom, or in a vertical displacement, and it will also perform it mounted flat on one of its heads. One use of any mufiier is in the capacity of a heat exchanger, the muflier being heated by the exhaust gases, and the body of the muffier thus transferring this heat to the atmosphere as the body of the muffler cools. It will become obvious that, for optimum performance, the muflier should be mounted so that air may circulate around the outside thereof. This is all according to conventional practice. The inlet 12 receives exhaust gases from the engine (not shown) in the direction of arrows 22. The gases travel through the inlet 12 into the expansion chamber defined by the side 11 and the heads 10, and are adapted to travel around the inner periphery of the side 11 at least one complete turn before being in the position to enter the outlet pipe 13 and be exhausted in the direction of arrows 23. This is because of the overlapping relationship of the inner ends of the inlet 12 and the outlet 13, within the expansion chamber. The exhaust gases thus travel in a rotary or spiral manner in the inside of the drum.

The exhaust gases enter the mufiler at a relatively high velocity and in a pulsating manner from the engine. As they enter the mufiler, they tend to expand in the expansion chamber, at the same time travelling in the hereinabove described rotary motion. Due to the velocity of the revolving gases in the muffler, portions of the gases are expanding towards the central portion or area of the muffler from all infinite points around the inner periphery thereof. This tends to set up a limited turbulence in the central area. The turbulent gases thus buffet, or cushion the pulsations of the entering gases, thus cutting down any resonance of the pulsations. Further resonance is virtually eliminated by the expansion of the entering gases, the expansion reducing the'volume of sound.

Sound waves are adapted to travel in straight lines, unless otherwise deflected, and are composed of vibrations of the medium which transmits the sound. In this case, the exhaust gases are the medium conveying the sound of the. detonations of the engine, along with other sympathetic vibrations. The gases are deflected around the inner periphery of the muffler, and are buffeted by expanding portions of the gases. sounds from the engine are thus muflled and blended into substantially a continuous rush of sound. The velocity of the exhaust gases is reduced as they expand in the chamber, and the gases are conveyed to the atmosphere fromthe outlet of the mufiler in one continuous rush. Due to this, there is no transmission of the resonant pulsatingengine noise to the outside.

In conventional mufflers, the entire volume of the exhaust gases causes a turbulence within the mufller which mufiles the sound of the engine. In this concept, the main portion of the exhaust gases is provided with a clear path of flow to the atmosphere, while a portion of the gases sets up a turbulence which bullets the main portion and muflles the engine noise. Thus there is no progressive back pressure as the engine speed changes, or as the work of the engine increases or decreases. Any force exerted by the engine on the exhaust system is immediately and completely transmitted to the atmosphere. Additionally, it has been found that backfiring of the engine through the exhaust system tends to be obviated by this method of muflling.

Another advantage of this mufiler is that backing off of the engine tends to be eliminated. Backing off occurs usually when the vehicle is travelling under momentum, and'the drive train of the vehicle is turning the engine at a speed greater than that demanded by the flow of fuelair mixture and/ or ignition. A nominal amount of backfiring is the result. Due to the method of conveying exhaust gases, it has been found that backing off tends to be eliminated.

The muffler may be installed at any point within the exhaust system of the engine and still perform equally well. An airtight seal with the connecting pipes of the system is provided in the conventional manner by means of slits 15 in the inlet 12 and outlet 13, allowing the pipes to make a tight, sliding fit with the connectingpipes.

It will be noted that no bafiles are employed in this invention. Bafiles cause excess turbulence of the gases, and are further disadvantageous in that they do not convey heat uniformly. Thus, hot spots occur at different points. These hot spots form excellent corrosion traps, causing early burning out of the muffler due to oxidation of the material.

The muffler is constructed of heavy gauge metal material, One material well suited to the mutfier is alu- The resonant, pulsating approximately 10 F. cooler than when the same engine was equipped with conventional mufflers.

It will therefore be seen that in this inventive concept, there is also a method of muflling resonant pulsating engine noise transmitted by exhaust gases from the engine. The gases are introduced tangentially into an expansion chamber and are adapted to rotate at least once completely around the inner periphery of the chamber and are then exhausted to the atmosphere. The major portion of the gases rotates around the periphery of the chamber, while a smaller portion or portions of the gases expand into the central area of the chamber setting up a 'turbulence,- and thence cushioning the major portion of the gases so as to muffle the resonant noises into a continuous rush of sound of reduced volume and pitch, and to convey the exhaustgases to the atmosphere from themufiler in one continuous rush.

It has been stated hereinabove, that engine coolant temperature 'has tended to' run approximately 10 -F. cooler in tests conducted. The test vehicle was driven at speeds aboveaverage highway speeds, and was accelerated, decelerated, causedto perform under heavy loading'conditions, and attempts were made to ba'ck firei the engine. Throughout-the tests, the mutfier tended to run cooler than the standard type conventional muflleri" The back pressure to the engine measured less than'40 percent of the back pressure'in a conventional mufil'er,"

and almost no backfiring could be induced.

A specific embodiment having been described and il= lustrated, it is to be understood that this embodiment is for the purpose of illustration, and that the invention is not to be limited thereto, but is to be construed as fairly falls within the true spirit and scope of the appended claims. V

I claim: i

1. A mufiler comprising an expansion chamber formed with a substantially cylindrical side and a pair'of sub stantially flat heads attached to said side, an inlet pipe disposed through said side tangentially thereto, and an pipe thereby overlapping each other.

2. The structure of claim 1 includingconnecting means between the inner ends of said pipes to obviate sym-,

pathetic resonance in the mufiler.

3. The structure of claim 1 in which said heads are under tension obviates drumming of the mufller.

4. The structure of claim 3 including connecting means ,1 between the inner ends of said pipes to obviate sympathetic resonance in the muffler.

References Cited in the file of this patent UNITED STATES PATENTS 2,205,024 Zinsitz June 18, 1940.

, FOREIGN PATENTS 1 688,224 France May 1 2, 1930v

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