US 1983304 A
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Description (OCR text may contain errors)
VDec. 4, 1934.
Filed July 24, 1929 5 l 1J J n.. m N n NNNNNN N f n U M f a. r R a j L u o f P 1 .F T NNN NNNNNNNNN NN NNN N N .Nd N N NNNNNNN n: N0 R E O J.. f H J. l f m f f a1 w n NNN N N N NNNN NNN i .NN NN N NN\N N N NNN f T- m l im A M. J n J j 3 l #y l j d @L Y NNNN NNNNNNNNNN ,w Bdg J f I f n N NN N N NN NNNNNNNNNN E .4 /1 H .v f NNNNNNNNNNNNNNNNNN NNNNNNNNNNA 0 Lw/IwwwV/Ilflfl :awww :IV Vn r A] M NN N N NN NNNNNNN NNN 2 H f J D1 n 3Q T. 1 nl /1 l ib@ n NN N NN N NNN N N n F NHT NNN N N KJ l NNN N N NNNNN NNNN NN NN. f NN NN NNN n T NNNNNN NNNN NN N N N N N N N Vr n j f f 5 \\\N\\ k. N \k NN N qll, 7 ru- 9 9 I d Y N Patented Dec. 4, 1934 UNITED l sTATEs PATENT OFFICE MUFFLER Application July 24, 1929, Serial No. 380,506
My present invention, while capable of a` Wide range of utility, nds its preferred embodiment in a muffler for motors or the like and is capable, for instance, of silencing the sound of a gas engine exhaust or a compressor intake.
An object of the invention is to provide a device of this type which not only shatters and dissipates the undesirable sound waves, but
which cleanses and lters the aeroform lluid` passing therethrough, these results being accom-- plished in every instance without the creation of back pressure in the mufller. v
I have discovered that a muliler in order to be effective, particularly where the muffler is of relatively massive size, as on the intake of an air compressor, must be substantially self-sustaining against vibrat-ion and the baille plates thereof must not only be leak proof but substantially non-responsive to vibrations in the current of air or gas which is moving through the mutlier chamber.'
ln accordance with the preferred embodiment ofthe invention, therefore, I employ a staggered series of solid baille plates arranged within a chamber having a restricted opening at one end and an air filter at the other end. The baille plates, which cause the air current to take a tortuous, frequently diverted p ath through the chamber, are not only rmly secured to the walls of the muiller body but have their free edges effectively sustained against vibration, preferably by connective tie rods. v
Preferably the baflles are of progressively increasing size from the filter end of the muffler to the end having the restricted opening through which the sound waves enter. The largest baille plate provides an air clearance opening between its free edge and the mufiler wall which is at least, as large as the sound wave inlet opening and this clearance becomes progressively greater at each baille, whereby a charge of exhaust gas, for instance, entering o ne end of the muffler under pressure escapes from the other end ofl the muffier under no pressure and in fact there is a. scarcely perceptible draft of lair through the filtering screen.
By leading the sound waves during their expansion and breaking up through a gaseous medium of progressively decreasing density, I'nd that a material damping and absorption of sound occurs and that the total muilling effect is far greater than where the sound wave passage is of approximately uniform cross section throughout its length.
The invention may be more fully understood Fig. 3.
- slots have their edges received in suitable grooves x from the following description in connection with the accompanying drawing wherein Fig. 1 is a longitudinal sectional view of the muliier taken approximately on the line 1-1 of Fig. 2 is a similar view taken at right angles to Fig. 1 and on the line 2 2 of Fig. 3.
Fig. 3 is a transverse sectional view taken approximately on the line 3 3 of Fig. 2.
Fig. 4 is a transverse sectional detail through one corner of the mulller body.
The mufller casing designated generally at 10 is of boxlike form, preferably approximately square in cross section and is provided with a removable wall 11 which for purposes of descriptive convenience may be designated as the top or cover. One end of the box has a sound wave inlet opening l2 of relatively small size therein encircled by a collar 13 into which the pipe 14 is fitted, this pipe representing, for instance, the exhaust pipe of an internal combustion engine or the intake pipe of an air compressor.
The opposite end of the box is closed by a filter screen which may assume many forms, although the illustrated embodiment has proven highly k satisfactory in use. This screen consists of a boxlike frame 15 of a cross sectional shape and size similar to that of the casing 10. Frame 15 is provided at one end With-a socket 16 adapted to be telescoped over the end of the muffler case 10 and defining a shoulder l1'7 against which the end of this casing abuts. One side wall of the frame 15 is provided with a series of transverse slots 18 therein and screens 19 entered through these 20 in the inner faces of the other three Walls of the frame. Preferably the series of parallel screens 19 are slightly spaced from each otherjand comprise wire mesh screen members carrying a coating or lrn of oil to which the impurities ln the gas flowing through the filter are adapted to adhere.
Two series of baflles of progressively decreasing size are arranged in the mufller casing. The lower series of baflles 21 rests upon the bottom of the box 10. These baffles are inserted while the cover l1 is removed. Their side edges are received in grooves 22 in the side walls of the box 10 and 'their lower edges received in a groove 23 in the box bottom. These ballles are equi-distantly 1 spaced from each other and are of progressively decreasing height from the sound wave inlet end of the box toward the screened end thereof.
A second set of baffles 24, having their upper edges received in grooves 25 in the box top l1, 110
of progressively decreasing size relativetoeachf.
other and to the lower baille set 21.
Considering Fig. 2 and the baille 24which7=sf closest to the opening 12, it will be noted that-the.
space-between the lower edge of this baille "and the bottom wall of the bom-:shouldbe-ofl-aicross sectional area which is approximatly'l quivalent-Y. (in most cases at least equal) to the cross sec-f" tional area of the opening 12.v 'Ifliedistance,bef v twen the next baille 21 and the top ofthe box is equal to approximately twice this area''ithefnex "7 wave" shattering qualitiesof an ordinary muilier baille.- cthree times theereaetc- "i'h''lsh'vvle l 'in use the sound vwaves enter l h rough "opening 1'2and as n ie creen areexpanded and travel through "a' progressively lessdense medium, and after. .traversing the' 'tortuous path# only. .the mechanicalsound interruption which afforded byf'the shattering o f 'the sound waves against the Abaille walls and thferepeat'ed sharp vchargcin directonof the waves but affords also a shock absorbing air or gas cushion of gradually decreasing density. Y 1 /have discovered this air lcushion to .be, "unusually effective in its sound deadening action Aand. experimentsindicate that thattheprovision'of a baille arrangement which permits gradual .expansion of the sound waves as .Well as rapid ,directional changes therein materiall'y assists the Aimpact of the waves against the baille walls'to'kill the noise ofthe exhaust. The present arrangement is notv to be'c'onfused with amplifier deviceswhere columns of air are in vibration and sound waves are expanding to- Ward the larger end of the column, since in such 'devices there is no continuous liow of air'current tending to maintain progressively varying air -are disposed in parallelism with the walls of the muliler casing and which extend from the free edge of the smallest baille of each set through all .of the other battles of both sets and through the sound wave entrance w'all of the muiiler casing. These tie rods are secured at their ends by nuts 30 or equivalent devices and'on each tie rod a pair of collars 31 are disposed at opposite sides `of each baille 4that the tierod intersects. Preferably these collars 'are jammed tightly against opposite faces of the baillesandheld in position by set screws 32. In assembling the muiller, .the lower set of bafv fles 21 are dropped into place, the upper set, of
bailles 24 are then dropped into position, the b ot-A toms of the grooves 26 checking their downward movement and bringing all their upper ends ush.
through the successivebale plates. Collars 31 are then moved against the bellies which-they are to hold, the set screws 32 tightened, and the tie rods secured. Subsequently the cover 11 is screwed tightly home. the notches 25 therein snugly receiving the upwardly projecting edges of the upper bathe set 24. The assembly may now bef-'completed by the application of the coupler collar-Sand the filter screen unit. I
. suggested above, the now of air or gas through the muffler may sometimes be in one direction and sometimes in the other, but the direcmaterial'fdifferenceein.the eieetiveness of the' muillingaction.v
. 'In use 'the inuille'v combines all of the sound with the unique air cushion actionor what might be termed a soundwave shock absorbing action afforded by' vthe 'progressively decreasing density of 'the air' through :which'the waves mustpass.
It will thus be'se'en -that'there is herein detionof sound wave movement is always through the opening 12 toward Vthe lter end thereof and .ivhethnthesefsoundwaves are moving with the -lair current or counter-current thereto makes no scribed a device in which theseveral features of this invention are er'r'ibo'died,` and which device in its action 4attains the '-various objects of the invention Vvand is 'well suited-to meet 'the require- As many changes could be'made in the above construction, 'and many' apparently widely'different embodiments" of this invention could be made without departing from the scope thereof, vit is intended that all matter contained in the above description or shownv in the accompanying drawing shallv be interpreted as illustrative and not'in alimiting sense.`
'Iclairnz' 1. A muiller including an elongated casing of generally rectangular cross sectional shape having a sound wave inlet opening in one end'and being open at its other end, a staggeredseries of generally rectangular sound wave shattering baffles extending transversely of the casing, said bafjles being'spaced alternately from oppositel walls of said casing and 4providing passages of progressively increasingsize `toward the open end of said casing.
'2. A muicr including an elongated casing of generally rectangular cross sectional shape having a -sound wave inlet opening in one end and being open at itsother end, a staggered series of generally rectangular soundwave shattering baffles extending transversely of the casing, each bale being fixed at three edges tothe casing walls and means to secure the free edges of the bafiles against vibration, said bales providing passages of progressively increasing size toward the open end of said casing.
' 3. A muler including an'elongatedcasing of generally rectangular cross sectional shape having a sound wave'inlet openingin one end and being open at its other end, astaggered series of generally rectangular sound wave'shattering bailies extending transversely of the casing, said bailies being spaced in alternation from opposite sides of said casing and ot-an extent to provide axial passages progressively larger toward the open end of sa'id casing, the casing walls being grooved to receive the edges of the baies and prevent leak therearound, and rods extending in parallelism from the inlet end of said casing through said baliles adjacent their free ends and having means clamping said baiiles in rigid spaced relation to prevent vibration of the free portions of the same.
4. A muler comprising an elongate casing open at one end for the discharge and having a restricted inlet at the other end, a staggered series 0f baies extending transversely of said casing, said bames being spaced in alternation from dia.-
metrically Opposite parts of said casing and of an extent to provide axial passages progressively larger toward the open end of said'casing, said casing having means for securely holding the free ends of said baffies against vibration and grooves receiving the other peripheral parts of said battles.