US854778A - Apparatus for muffling the exhaust of gas-engines. - Google Patents

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' PATENTEDMAY-Zii, 190

u w E. THOMSON. APPARATUS FOR MUFFLING THE EXHAUST OF'GA'S ENGINES.

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Ynvehof: E/i/w Thomson PATENTED MAY 28 E. THOMSON. APPARATUS FORMUPFLING THE EXHAUST 0F GAS ENGINES.

APPLICATION FILED AUG. 20, 1904.

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- /nvenlfior'. E/ihu 77101715017,

unnn' TAT S PATENT orrron Benn; THOMSON,

.or'SWAi rrScoTr, MASSACHUSETTS, ASSIGNOR TO QENERAL ELECTRIC COMPAN Y, A CORPORATION OF NEW YORK.

APPARATUS Fon-luu lume' THE EXHAUST oF GAS-ENGINES.

Specification of Letters I'atent.

Patented May 28, 1907.

Application filed August 20,1904. Serial No 221,472.

'. all whom it may concern: I

it knownthat I, ELIHU THOMSON, a citizen the United States, residing at Swampscott, countyof Essex, State of Massachusetts, have invented certain new and useful Improvements in Apparatus for Mufiiin the Exhaust of Gas-Engines, of which the fo low-,

mg is a specification.

. It is well known that the exhaust from as ID or explosion engines produces a disagreea le noise which partakes of the nature of an explosion. To overcome this, ObJGCtlOh various kinds of mufflers have been provided which reduce the sound to a certain extent. As a I 5 general proposition it may be stated that the more these mufliers reduce the sound, cs pecially when of small interior volume, the greater will bethe back pressure created thereby. In other words, all such mufilers cause considerable loss in efficiency, which less increases as the sound decreases. I

have discove ed however that the sound of the exhaust can ,be decreased to a point where it is unobjcctionable, .and this without the loss of any substantial amount of energy, by breaking up each sound wave into parts and delaying one or more parts behind the other orothers, so that theirdeliveries to the point of .final discharge will lag in time one with respect to the other or others. In

other Words, my invention depends upon the acoustic princlple of interference between impulses, and the sound wave for each exhaust discharge, instead of having a high and well defined sharp peak, is flattened and. the discharge takesjplace' with a low hissing sound.

In waoticing my invention a chambered rece Jamie is provided having a number of -ed discharge orifices, through which the eaust gases pass on their way to the point o. final discharge. These orifices are so arranged that practically speaking they all re ceive their portion of the exhaust products at the same time, and between them and the point of final exhaust are one or more conduits or passages. The conduit or conduits are so arranged that it or they receive the exhaust from a nrmber of different orifices, the latter however being so, arranged that the gasescaping from some of them has a longer path to travel than the gasescaping from the ries of orifices. Th

remaining orifice or orifices. In other words, one increment of gas or vapor due to a given impulse 'has to travel a certain distance in orc e1 to escape, while another increment has to travel twice as far, and a third has to travel three times as far and so on. An elongated slot, tapering in width, might replace the see orifices are preferably, so arranged that either their area decreases toward the point of discharge or, the area remaining the same, the number decreases. In either case there would be a gradual decrease in the effective area of discharge. With the construction described tests show that there is virtually noback pressure, the

sound is reduced to a point where it is unobjectionable,-an'd the muflier asa whole is a smaller than those customarily employed for the same size and type of engine.

1n the accompanying drawings, which illustrate an apparatus for practicing the invention, Figure 1 is a view showing a gas engine connected to a muffler of improved construction, the latter being shown in longitudinal section, Figs. 2 and 3 are detail views showing the construction of thedisks used to form the exhaust-conveying passages; Fig. 4 shows a slight modificationin the construction of the mufiier; Figs. 5 and 6'show the disks employed in forming the gas-conveying passage; Fig. 7 illustrates a construction wherein the orifices admitting as to the elongated gas passage successive y decrease in area instead of being of'the same size and 85 decreasing in number, as in Figs. 1 and 4," Fig. 8 is a diagram showing the effect of my improved mufiier, and Fig. 9 isa further modification.

1 represents the engine, which may be of' any suitable character and operated by gasolene, kerosene or other similar form of energy. The exhaust from the engine is discharged into a chambered receptacle 2 which in the resent illustration takes the form of a 9 5 tube t atis open on the end adjacent to the engine and closed by suitable means, such as a cap 3, at the op osite end. This receptacle is rovided Wit/i l a plurality of dischargeori ces 4, which orifices are graded from one Ioc' end of the receptacle to the other; that isto say, the orifices are the most numerous near amount of gas or other vapor will 11 which corresponds in size tojthe external progressively l the inlet end of the tube 2 and Ina decrease in number toward the ca stead of decreasing the number orifices, the same number may bee loycd, but the size of the orifices should be ecreased from 1 the inlet toward the closed end of the tube 2. 5 By reason of this construction a later- IS.- charged at the inlet'end of the' 'chambered receptacle than at the closed end. Surrounding the chambered receptacle is 2. cylinder 5 which engages the heads 6 and 7 that are mounte on the tube 2. These heads are secured inplace by suitable means such as the nut 8 and cap 3. The head 6 is made solid, while the; 7 is perforated, as at 9, to permit-the products of combustion or other vapor to escape. The interior of the cylinder 5 is divided up by partitions 10 arranged to form anelongated passage. The right-hand end of the assage or en adjacent to the engine is close while the outer end is in free communication with the orifices 9 that communicate with the atmos )here.

In .igs. 2 and 3 are shown the disks for forming the spiral massage round the tube 2.

Each disk-is provi ed with a central opening diameter ofthe tube The disk is out, as at 12, to form the lip 13, which .lip is offset a distance equal to that between the disks when assembled as in Fig. 1. The disks are slip d over the tube and are bolted one to the ot ier and to the head 6 by bolts 14, suitable spacing devices such as tubes or nuts 16 being emplovcd to preserve the pro or relationship of the arts. When the dis 's are. assembled as in ig. 1-, a spiral passage is formed beginning at the right-hand end of the mulller, which is in communication with all' of: the on'ficess. Since all of the orifices receive gas or other vapor in multi la and at substantially the same time, it;fo ows that the increment of gas or other vapor issuing, from the orifices 17 has a greater distance to .travel than a similar increment issuing from the orifice 18. In the present illustration the difference in distance traveled is equal to the length of a )ath once round the tube 2. It also follows t lat the distance traveled by increments of gas or other vapor issuing from orifices nearer the inlet end ofthe tube will have a correspondingly greater distance to travel.

The particular mulilcr illustrated has been used in honncction with an ex )losion engine of the four-cycle type dcsignc to use either i gasolcnc or kcroscnc, and to deliver between eight and ten horsepower. The numberand arrangement of the orifices can. be ehan d l to suit the requirements. In' the mu ler l under consideration the first turn of the spiral passage was provided with about ten holes, each from to a quarter inch in diameter, and the number of holes successively decreased toward the lel'tdmud end. For convenience in constructing thc appnratus, holes of the same size may be cmplo ed for each turn, but I have found it rather more satisfactory to have the ol'iliccs on the right-hand cnd somewhat larger in diameter than those on the left-hand end.

in order to lighten the construction as much as possible and at the same time to give it the requisite strength, it is desirable to employ a construction such as illustrated in Figs. 4 to 6 inclusive. .10 represents a piece of tube or pipe which is provided with a coarse screw-thread 21 to receive the d sks 22. The la ter are each provided with a central opening 23 to receive the tube. 'lhcv are also split, as at 24, to permit of the disk being bent to form a spiral likev a screwthrcad as shown in Fig. 5, the edge of one 5 disk being f-wvidcd with an offset 25 to receive the ct go of the adjacent disk. Mounted on the tube are heads .26 and 27, the

former being solid while the latter is rovidcd with perforations 28. The total Toss-sectional area of these perforations should preferably exceed the total cross-sectional area of the oriliccs in the tube 20. Surrounding the disks is a sheet-metal cylinder 29 that is retained in place by a binding band 30 made of wire. It is to be noted that the wire slightly depresses the metal between the spirally arranged disks, which holds the edges of the latter in place and rcvents them from rattling. 'lhc Wirc-shou d be made of steel or equivalent material and be put on under tension, and the ends suitably fastened.

The discharge end of the mufller may be rovided with a neck or nozzle 31 as shown in 1 ig.'1, in order to direct the outgoing body of gas or vapor, but this is not essenl iio.

It will be seen from this construction that the length of the path of gas escaping from the orifices 4 difl'elrs greatlv between the right-hand and the lei'hhand end ol' the null ller, the said paths successively decreasing in length from right to lel' t. The rate of travel of the gas impulse at ordinary atmospheric pressures and at about the density of air. is about 1000 feetper second. With a (l('ll ('r fins the rate is slower. The gas escnbiuf from the numerous holes at the rigludmnd end has to travel practically ten times around the inner tube. 2o. Another portion of the gas has to travel nine times urouud the tube, and another portion eight and 0 on. The gas csca )inglrom the hist holc n the. discharge en of the tube may pass directly through one of the orifices 28. or it' mu) pass a fraction of a turn or even more than i: turn round the tube.

' ,n'oises produced instead of passin stood t at this figure does not however rep- 'strated by coupling the engine to a dynamov i What I claim as new and desire to secure by Letters Patent of the United States, is,- I 1. devicedischarging gas or vaporin the form of impulses, in combination wi ii In Fig. 7 is shown asection of a tube 32 l wherein the gas-discharging orifices 33 successively decrease from right to left.

In Fig. 8 is shown diagrammatically the ,l effect whichis hrought about by the .use of l my im roved nniiiier. It is to be undertacle, an elongated municating with the receptacle and passage, resent the exact relationship which exists. 34 represents an impulse from a gas en ine greatest at the inlet end of the receptacle.

2. A device discharging gas r vapor in the form of impulses, in combination with a muffler comprising a chambered receptacle, a plurality of orifices arranged to simultaneouslydischarge gas or vapor from the chamber, and means causing a greater retardation of the passage of gas or vaporbetween certain of the orifices charge than between others."

3. A device discharging ga'js'or vapor in the form of impulses, in combination with a muffler comprising is closed at one end, discharging the contents when the muflier is not employed,,an 35 l represents the relationship between the arts l of the same impulse when lagged behin one another due to the effect of the muflier. In l other words, 34 re resents a sound wavehaving a well define and sharp peak, while 35 represents .a sound wave which lasts longer, I but is much smoother and of lower pitch.

By actual test l have demonstrated that there is practically no back pressure when this muflier is employed. This is demonplurality of orifices forload and employing a volt and ampere meter of the receptacle,

to make readings. With a constant load I have found that throwing the muffler on and of]? does not make a difierenceof more than one-half to one per cent. At a dista ceQof some thirty feet from the engine the sound of the exhaust is hardly noticeable, the

by the cams, etc. being the 4. In amufiier, the combination of arecepprominent sounds. tacle having a plurality,of discharge orifices It will be evident that the same principles. which decrease in crossesectional area as they of action are fulfilled if, instead of letting the 'recede from the inlet to the receptacle, and gas flow in the direction ,shown and. demeansfor causing the body ofgasor vapor scribed in Fig. 4, it moves .in the direction discharged by the orifices nearest the inlet to shown by the dotted arrow; in fact I find .travel a-greater distance than those more ref that the arrangement works well whichever mote. L the direction of flow. 5. In a'muffler, the combination of'a recep- A slight inddilication is shown in Fig. 9 in which there is a pipe 20 extending through one of the orifices is longer'than rom the other or others.

tacle, which is open at. one end and closed at the other, a lurality of discharge orifices the casing which is divided by a septum or contained in t partition 37, in advance of which are numerous holes, so that the gas enteringsuch ipe g directly therethrougi is turned aside into the outerspace, and traverses the elongated or spiral passage. The exit portion of the pipe 20 has a similar series of openings from the turnsof the spiralpas sage, which is described in connection 'with' other figures, the area of the number of openings increasing toward the outlet, preferably. .l t will thus be seen. that the arrangement, 5 means for carrying ofl the gasor vapor from Fig. 9, isiiirtually the same as Fig. 4, except 4 the tube, the said orifices that the construction is somewhat simplified to split up the sound waves and to-lag one and the gas finally escapes throughthe pipe portion with respect to another. 20 at a point beyo'iid the partition 37. 7. In a muffler, the combination of an In accordance with the provisions of the elongated passage, with apluralit of orifices pa ent statutes I have described the princi- 1 discharging into it in multiple, toe-said oriple of operation 01"" my invention together lfices being graded so thatthe amount of gas with the apparatus-which I now consider to i or vapor passin'g through them gradually represent the bestembodiment thereof, but l decreases toward the point of I desire to have it understood that the appal the passage. ratus shown is only illustrative, and that the i 8. In a muflier, the combination of a chainout by'other means. I bered receptacle arranged to receive the exthe closed end, a helically arranged assag e communicating with the orifices an so arranged that the gas "or vapor from some of the, orifices travels farther than from others. a 6. In a inufiier, the combination of atube which is open at one end and closed at the other, a plurality of discharge orifices for said I tube which decrease in effective cross sectional area toward the closed end, and a invention can be carried and the point of final dise receptacle: which gradually decrease in total area from'theinlet toward and means actingdischarge of haust impulses from an engine, means for 5 the tube and I'C'PPiHH or vapor [nun the ln'vnking up the continuity of eacibimpuise uriiiws. Lhv tuhv uni} orifices heingurrangvd and other means coiiperating with the first to 5 tu ('uust' a part ur par-v; of the impuise to issue cause the sevural parts of the impulse to issue hniurv :muliwr pa [-1 w parts.-

5 sLwcessivr-iy. In NiLIll'SS whvruul, i lwwunio set my 15 9. In a mufiier, the cumbination of u tube hand this lTl h (my ui' August 100-}.

having an admission and a QlOSGd end, orifices E111 HU 'IIIOBISON. arranged in the tubeyhvhihdischarge ga's 0r Nitllessvs: valfbr from the tube and are arranged in inul- JOHN A. Mchlixxus, JIL,

lo tip 6, and a spiral passage which surrounds & DuuAu) Mali. MUKILLOP.

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