US1611475A - Silencer - Google Patents

Description

Dec. 21,1926. 1, 11,475

H. P. MAXIM S ILENCER Filed March 26, 1922 BY "W ATTORNEYS Patented Dec.. 21, 1926.

UNITED STATES mama run SILENCER nnorrour.

OMPANY, OF HARTFORD,

PATENT OFFICE.

CONNECTICUT, A CORPORATION OF CON- SILENCER.

Application filed. March 23, 1922. Serial No. 546,126.

The present invention relates to silencers or mutflers such as are used in connection with gas or oilenginesto reduce the noise of the exhaust or in connection with various kinds of steam and pneumatic machinery for deadening the discharge or intake noises thereof.

One object of the invention is to provide a mufller or silencer of the eneral character above mentioned which wil effectively perform itsfunction without creating back pressure.

To this end, the invention contemplates broadly the provision, in an exhaust or intake muflier, of asilencing conduit constructed and arranged to obstruct the escape of the sound waves without throttling the flow of the sound propagating medium.

' In carrying out this feature of the invention the silencing conduit is made to comprise at least one section, the walls of which are shaped in accordance with the principles of Venturi tube construction to provide a gradually contracting portion and 85 a gradually expanding portion, the former beingv arranged to discharge into the latter. As the exhaust gases pass through a conduit constructed in this manner the sound waves which strike the tapering walls of the con tracting portions are reflected backwardly and are trapped and as a result only such sound waves escape as pass directly through the small end of the contracted portion with-' out striking against the converging walls thereof. By reason of the Ventnri action of the expanding or diverging portion of the conduit, the velocity of the gases is increased in the restricted portion to such an extent that the volume of flow per unit of time of said gases or propagating medium is not materially reduced and consequently the discharge capacity of the conduit is not-reduced and no undesirable back pressure is created.

Another object (if the invention is to pro ide, in an exhaust muffler for internal combustion engines, 'lneansxwhereby the head or advance portion of the intermittent "or pulsating stream ofexhaust gases will serve to draw out the tail or rear portion. of the latter, and thus to assist in scavenging the engine cylinders.

Another object of the invention is to provide certain new and useful improvements in.

and claimed, the advantages of which will,

be apparent to those skilled in the art.

In the accompanying drawings,

Fig. 1 is a longitudinal sectional view of a silencer embodying one feature ofthe present invention Fig. 2 is a section on the line 2-2 of Fig. 1; I

Fig. 3 is a view similar to Fig. 1 showing a modification of the construction illustrated therein; I

Figs. 4, 5, and 6 are longitudinal sectional views of silencers embodying in alternative forms certain additional features of the present'invcntion.

Referring first to Figs. 1 and 2 of the drawings, the silencer or muflier therein illustrated consists of a conduit comprising a plurality of sections 2, each having gradually.

contracting portions 3 and. gradually expanding portions 4 relatively arranged to producethe effect of the well-known Venturi tube upon a fluid or gas flowing therethrough. The inventor" has discovered that by providing, in a silencing conduit, one or more tubular sections having converging walls as in the case of the illustrated sections 3, most of the sound waves will strike the converging walls and be reflected backwardly so that they will be effectively trapped, the only sound waves finallyiescaping beingthose which pass directly through the several re stricted portionspf the conduit without first engaging any portions of the walls thereof.

It is very important in most engines'and in many forms of machinery in connection with which mufliers are ei'nployed that the exhaust or discharge shall not be obstructed so as to produce back pressure in the engine cylinders or pressure chambers of the machinery.

,To prevent the creation of back pressure the present invention contemplates the employment, in conjunction with the contracted sections 3, of the tabular sections 4 having graduall diverging side walls, thelatter regularly recurring contractions and exsections eing arranged to receive the sound propagating medium directly from the small agating gases. 7 1

ends of the converging sections 3 and to Fig. 4 is illustrative of a'silencer which draw said medium through said converging embodies another feature of the present insections so that its flow will not be substanvcntion. As shown, a continuous tube 6 is tlally retarded therein. provided with a series of Venturi sections 7 pansions in the stream of thesound prop-,

As the gases which carry the sound waves which may be similar to those already de- 1 flow through the expanding sections 4 of the scribed in connection with the Figs. 1 and 2.

conduit these sections act in substantially the The tube 6, which serves as a conductor for same manner as a Venturi tube to expand the exhaust gases or other sound propagatthe'stream of gas and to lower its pressure ing medium, fits tightly within a cylindrical and thereby to assist in increasing the distube '8 to form annular compartments oi charge capacityof the conduit. Furtherchambers 9 between the enlarged portions more, the noise values are spread over a of the tube 6, each chamber 9 being sub-' much greater area and consequently their stantially gas tight except for connections value per square inch becomes much reduced. through a plurality of ports 10 to the inner As the gases pass through the contractin sections 3, the sound waves are reflected an the noise value of those waves which escape tube 6 at the region of lowest pressure in the respective Venturi section of said tube. \Vith this construction the sound waves through the small ends of these sections bear are reflected backwardly by each converging the same relation to the noise value of the wall portion of the tube and by reason of waves entering said sections .as the minimum the shape of the succeeding diverging wall cross-sectional areas of these sections bear to portions the flow of the gases is not matethe maximum cross-sectional areas thereof. rially impeded. Furthermore by reason of Thus, each time the gases enter a new conthe low pressure which exists in the retracting section, a relatively large quantity stricted portions of the Venturi sections 7 of the remaining sound waves are reflected the gases in the chambers 9 are partially exbackwardly and trapped and only a. relahausted through the ports 10 at each pulsatively small quantity are permitted to escape. tion of the exhaust, leaving a partia vacuum Consequently by -employing a sufficient numwithin each of said chambers. This partial ber of contracting sections in the silencing vacuum in the chambers 9 satisfies itself conduit nearly all of the sound waves will from or, in other words, is relieved by the ultimately be trapped so that the noise will following gases. Thus the head of each be practicall silenced by the time the exexhaust pulsation becomes effective to pull haust gases all emerge fromthe silencer. out the tail thereof and thus to secure I It will be un erstood that by reason of complete scavenging of the engine cylinders the Venturi action of the diverging sections or other pressure chambers- The inner tube 4, the velocity of the flow through the re- 6 may be rigidly secured in any suitable stricted portions of the conduit will be inmanner to the outer tube 8 or the tubes 6 creased in proportion to the amount of reand 8 may be detachably'held in assembled duction in cross-sectional area of the conrelation by means such as a spring latch 12' duit at these points. Thus substantially the which may be released to permit convenient same volume. per unit of time will pass removal of the inner tube for cleaning purthrough said restricted portions as passes. inl poses.

' the same time through'theunrestricted por- .A modification of the construction just dctions of the conduit. Accordingly, the least scribed is shown in Fig. 5. In this figure possible resistance is offered to the flow of the silencing conduit comprises a seriesol' the gases, the discharge thereof is practiseparate sections 14 each having a contracted cally unretarded and no back pressure is inlet 15', an enlarged intermediate portion created. 16 and a contracted outlet 17. The inlet 15 It is of course, hf importance that the of each section 14 is of somewhat largerdiwalls of the converging portions of the Venameter than the outlet 17 thereof and the turi sections shall be so shaped and pitched several sections are arranged in axial alineas to reflect the Sound waves to best advanment. The outlet of each preceding section tage Without creating 00 mll h fr c ional reis arranged totelescope within the inlet of sistance to the flow of the gases in which the each succeeding section. Thus the forward sound waves travel and also that the dihalf of each section 14 and the rear half verging portions of the Venturi sections shall of the section 14 next in advance thereof in be properly proportioned to produce the decombination constitute a Venturi section sired effect .upon the flow of the gases. such, in eflfechas the Venturi sections in the In the modified construction shown in Fig. forms of silencers heretofore described. 3, fhe several Venturi sections 5 have been The separately constructed sections 14 may non-uniformly spaced in the conduit to break be independently secured wlthin an outer I up the resonance resulting from a series of cylindrical tube 18 by means of screws or sections or units 23 which correspond to the conduit sections 14 of the construction shown in Fig. 5. Each unit 23 includes, in

I addition to the expanding and contracting ortions 24 and 25 through which the exaust gases flow, a tube 26 which cooperates with similar tubes on other units 23 toconstitute an outercylindrical shell in which low pressure chambers 32 are formed. As shown, the outer tube 26 of each unit 23 is made integral with the contracting portion 25 While the expandin portion 24 is riveted at 27 to large end of the contracting portion 25. The tubes 26 of the several units 23 have universal joint connections with each other thus providing mmufller'conduit which is flexible and may be bent to avoid obstructions or otherwise adapt itself for convenient vinstallation. To this end each tube 26 is formed with spherically curved end portions 28 and 29, the portions 29 of each tube- 26 constituting a socket for receiving the portion 28 of the adjacent tube 26 thereby orming a ball and socket joint connection between. said tubes 26. The tubes 26 are made of such length as to insure that the units 23 will be arranged with their outlet and inlet'ends telescoping but separated by 'the details of construction and arran ement' of parts may be resorted to without eparting from the spirit and scope of the invention as hereinafter claimed.

Claims:

1. A muflier forsilencingtheexhaust of an internal combustion'engme comprislp' g a conduit for thefe'xhaust gases having a nturi-like passageway ther'ein'and a clia ber l closed on all sides except. for an -openin therefrom into the restricted portion of sai A passageway. v

2. In a muflier for silencing the exhaust of an internal. combustion engine, a conduit comprising ayconverging section and B/dif .verging section, said converging section opening into said diverging section to provide a Venturi-like passageway therebetween and a chamber closed on all sides except for an opening therefrom into the re stricted portion of said passageway.

3. In a mufiler for silencing the exhaust .of an'in'ternal combustion engine, a conduit comprising a series of alternate converging and diverging sections, each converging section opening into the next succeeding diverging section to form. a series of Venturi-like passa eways in said conduit, and a separate cham r surroundin each passageway, each being closed at all sides except for an opening therefrom into the restricted portion of its respective passageway.

4. A mufiier for silencingthe exhaust of an internal combustion engine having, in combination, a conduit for the exhaust gases comprising a converging section and a di-' verging section, the converging section having its contracted end telescoping within the contracted end of the diverging section and separated therefrom by an annular space, and agas tight chamber surrounding said contracted ends and communicating with the interior of said diverging section through said annular space.

5. A mufiler comprising a flexible conduit for a sound propagating medium comprising a plurality of. separate longitudinal sections directly joined together by flexible joints to permit a limited amount of uni-. versal movement between adjacent sections,

and saidsections having passagewa s con structed and arranged to obstruct t e pas sage of the sound waves. v

6. A muflier comprising a flexible conduit for the sound propagating medium comprising a pluralit of se arate lon itudinal sections direct y joine together by a flexible. jointto permit a limited amount of universal movement between adjacent sections, said sections combining .to afford a succession of Venturi-like passages for obstructing the sound. waves without throttling the flow of the sound propagating medium. p I

'7. A mufiier comprising a flexible conduit for the sound propagating medium consisting of a. plurality of longitudinal sections joined together to permit. a limited amount of universal movement between adjacent sections, said sections combining to afford a successionof Venturi-like passages for obstructin .the' sound waves without throttling the ow of the sound propagating medium, anda series of low pressure chambers communicating with the'restricted portions of said. passages.

8. An exhaust mufiler having, in combiv nation, a series of units each comprising di-. verging and converging inner conduit sections and an outer tubular section having two spherically curved portions spaced longitudinally thereon, one of said curved portionsoneach tubular section being adapted and arranged to provide when assembled a mufiier conduit having a succession of Venturi-like silencing passages. y

In testimony whereof I have affixed my signature.

HIRAM PERCY MAXIM

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