US2822885A

US2822885A - Air cleaner and intake silencer assembly

Info

Publication number: US2822885A
Application number: US411612A
Authority: US
Inventors: Joseph B Sebok; Ralph E Sendelbach
Original assignee: Purolator Products Inc
Current assignee: Purolator Products Inc
Priority date: 1954-02-23
Filing date: 1954-02-23
Publication date: 1958-02-11
Anticipated expiration: 1975-02-11

Description

Feb. 11, 1958 J. B. SEBOK ETAL 2,822,885

AIR CLEANER AND INTAKE SILENCER ASSEMBLY Filed Feb. 23, 1954 5 SheeQs-Sheet l EZE'ILZZU T5 (Joseph B. Saba t ZEa/ E. fiendelbach fiH H Feb; T1 1958 J. B. SEBOK ETAL 2,822,885

AIR CLEANER AND INTAKE SILENCER ASSEMBLY Filed Feb. 23, 1954 5 Sheets-Sheet 2 u M? N I N n 7 7 I: I I I: 1 I w" l rw J "D N N i N \\n v i we ,1 k i EYFETZZETE Joseph B. 156b71 Pa 1,012 5. sew/611142 12 Feb. 11,1958 J. B. SEBOK ETAL 2,822,885

AIR CLEANER AND INTAKE SILENCER ASSEMBLY Filed Feb. 23, 1954 5 Sheets-Sheet 3 I 271 5 IZfQTS Joseph B. 565012 g 754/52 5. Sande/bash HZZLjS Feb- 11, 1 5 J. B. SEBOK ETAL 2,822,885

AIR CLEANER AND INTAKE SILENCER ASSEMBLY Filed Feb. 23. 1954 5 Sheets-Sheet 4 2 gg m Feb. 11, 1958 J. B. SEBOK ET AL 2,82 ,885

AIR CLEANER AND INTAKE SILENCER ASSEMBLY I Filed Feb. 23. 1954 5 Sheets-Sheet 5 E-FE 7:2 Zn T5 i Fez/f1 5 Sendelbacfi United States Patent AIR CLEANER AND INTAKE SILENCER ASSEMBLY Joseph B. Sebok, Dearborn, and Ralph E. Sendelbach, Detroit, Mich., assignors, by mesne assignments, to Purolator Products, Inc., Rahway, N. J., a corporation of Delaware Application February 23, 1954, Serial No. 411,612 22 Claims. (Cl. 183-15) This invention relates to improvements in an air cleaner and intake silencer assembly, and more particularly to such an assembly highly desirable for use in connection with internal combustion engines of the automotive type,

although the invention will have other uses and purposes for mechanisms requiring an air and also desirable silencing emanating from the intake, skilled in the art.

For purposes of clarity'and adequate disclosure, the instant invention will be herein considered in connection with its use in association with a carburetor of an internal combustion engine, such as the commonly known automobile engine.

adequate supply of clean of intake noises or noises as will be apparent to one I-Ieretofore, the type of intake silencer commercially used with automobile engines has universally been a silencer operating upon resonator principle, and wherein a casing was arranged to provide a chamber of predetermined volume whch communicated with a path through which sound waves might travel, but was otherwise closed.

In many cases communication was established with the resonator chamber by way of a tube concentric with but spaced from an air duct, and in other cases by way of a tubular element having apertures therein. Of course, the resonator chamber was to attenuate a sound of predetermined frequency, this being in most cases the fundamental tone of the automobile engine. The tuning of a resonator chamber to a particular frequency depends upon the volume of the chamber and the charactor of the acoustical coupling by which communication is established with the path traveled by the sound waves. Most frequently the resultant tuning was accomplished by varying the size and length, or both, of the tube establishing communication with the chamber, and that tube was frequently referred to as a tuning tube. In some instances compound resonating chambers or resonating chambers connected in series were'utilized,

simple expedient to provide a tuning tube for connection with the carburetor intake horn, and terminate the clean air outlet tube inside that tuning tube, but spaced therefrom.

However, the difficulty of providing adequate silencing for an automobile engine has tremendously increased with the advent of higher horsepower engines, and lower hoods on automobile, thereby limiting the space in which attenuating chambers cated. This tendency toward lower hoods and less space of adequate volume may be lo-' in the engine compartment has now progressed to such an extent that in a number of cases the air cleaner and silencer assembly must actually seat down over and house the major portion of the carburetor, the former housing which was an integral part of the carburetor and to which the intake horn was attached having been eliminated. That required the central portion of the air cleaner, or in effect, the clean air outlet conduit, to be enlarged so that the upper part of the carburetor could be received inside the air cleaner-silencer assembly. In some cases, this enlargement was up to three times the previous diameter. In many instances it was also desired to reduce the overall height, from cleaners and silencers used theretofore. As a result, extreme difficulty was experienced in finding space for a resonator chamber of adequate volume to effect the desired silencing, and increase in engine size usually requires a greater volume in the attenuating chamber. Even greater difficulty has been experienced in endeavor-ing to tune such an attenuating chamber of the true resonator type to a predetermined frequency because of the greater chamber size, and more particularly because of the lack of room for an acoustical coupling to that chamber in the form of a tube which could be lengthened or shortened or varied in diameter.

Endeavors to solve that problem have resulted in complicated structures of highly expensive character, and in many cases prohibitively expensive for commercial production and acceptance.

The instant invention effectively and economically solves the foregoing problems.

Inasmuch as the theory or principle of operation of the instant invention has not as yet been fully determined, and it is not yet known whether or not the instant invention effects sound attenuation on the principle of operation of a true resonator attenuating chamber, the attenuating chamber will be herein referred to as a volume or silencing chamber, for purposes of accurate presentation, the actual efiiciency and efiicacy of the instant invention having been conclusively proven in practice.

With the foregoing in mind, it is an object of the instant invention to provide a new type of silencer embodying a tuned volume chamber.

Another object of the invention resides in the provision of an air cleaner-intake silencer assembly designed for disposition over the major portion of a carburetor, and the silencing means of which includes a volume chamber which is easily and economically tuned to a desired frequency.

A further object of the invention resides in the provision of a volume chamber type of silencer that can readily and economically be varied at the time of manufacture to be eifective on several different automotive engines, without resort to expensive die changes, or provision of duplicate dies, or a reconstruction of the main part of the silencer.

It is also a feature of the invention to provide a volume chamber type silencer for internal combustion engines, so constructed as to provide a great range of tuning which may be accomplished with no change whatever in the overall dimensions of the silencer.

Another feature of the invention resides in the provision of an air cleaner-intake silencer assembly wherein the silencer involves a volume chamber, and the tuning tube for the volume chamber also functions as an air inlet to the air cleaner.

It is also a desideratum of the instant invention to provide a volume chamber type intake silencer with the tuning tube therefor located wthin the volume chamber.

Still another object of the invention resides in the provision of an air cleaner-intake silencer assembly in which sound emanating from the internal combustion engine or other source is passed through the filter element of the air cleaner before reaching the volume chamber of the silencer, thus causing the filter element of the air cleaner vision of an air cleaner-intake silencer assembly,- inwhichthe silencer involves a volume chamber readily tunable,

and incoming air passing through-the -aircleaner also passes. through the volume chamber of the silencer.

,Still another object of the invention resides-inthe provision of an aircleaner-intake silencer-assembly, wherein the filter element of the air-cleaner may be separately removed, the cleansing liquid container of the 'air cleaner may be separately removed,-and the silencer casing left in position.

Also-a feature of-the invention is the provision of an intake silencer of the volume chamber type wherein the overall height ofthe structure is reduced to a minimum.

While some of themore salient features, characteristics and advantages of the instant invention'have' been above pointedout, others will become apparent from the following disclosures, taken in conjunction with the accompanying drawings, in which- -Figure 1 is-abottom plan view of an air cleaner-intake silencer assembl-yembodying principles of the instant invention;

Figure-2 is anenlarged fragmentary part central vertical sectional, part side elevational view of the structure of Fig. 1, showing the same in operative association with the carburetor of an internal combustion engine;

Figure 3 is a'fragmentary central vertical sectional view showing a slightly. different form of construction for the assembly of Figs. 1 and 2;

Figure 4 is a bottom plan view of an air cleaner-intake silencer assembly embodying principles of the instant invention but illustrating a different construction of the silencer portion;

Figure 5 is a fragmentary centralyertical.sectional view through the structure of Fig. .4;

Figure 6 is a fragmentary central vertical sectional view through an air cleaner-intake silencer'assembly embodying a still different form of construction; and

Figure '7 is a part central vcrticalsectional, part side elevational view of a cleaner-silencer assembly embodying an extra true resonator chamber, in addition to the volume chamber disclosed in the above structures- As shown on the drawings:

That illustrated embodiment of the instant invention seen in Figs. l and 2 is shown operatively associated with a carburetor of the so-called downdraft type. This carburetor in and of itself does not.form .a partof the instant invention and need not be of the particulapstructure illustrated. The carburetor itself includes a base portion 1 which may house the usnalventuriandthrottle valve and is the portion through which the combustible mixture passes. On top of this base portion is anannular flange or platform 2 which functions-asp 'seat for-theair cleaner-intake silencer assembly. The choke valve of the carburetor willusually be located substantiallyin the plane of the flange ,2. Above that fla' ngethecarburetor includes the usual float chamber arrangement '3, vanzaccelerating pum n ement stand. .lothe parts .com;

monly utilized in-carburetors for internal combustion engines. It will be noted that the carburetor utilizedwith the instant invention does not include the customary cast housing over all the upper portion thereof and which housing terminates in an air intake horn. In this instance, incoming air surrounds all the portion of the carburetor above tthe-flange 2, and that part of :the carburetor is housed or enclosed by the aircleaner-silencer assembly. Obviously, the carburetor may be of the single or dual type, depending upon the character ofengine it is'to supply with fuel. In..Figs.;5- to 7, Ihave indicated the same type of carburetor in dotted lines.

The .air. cleaner-intake silencer assembly includes an outer casing or shell, preferably fabricated from separate pieces to save cost in manufacture and including a bottomed cylindrical lower portion 5 and an upper portion 6 lock seamed or. otherwise secured to the lower portion as indicated at 7. While it'is desirable for manufacturing-economy tomake asmany'casing portions of an air cleaner as possible of cylindrical contour, in the present instance theupper portion 6 of the shell is made somewhat eccentric, to project beyond the lower portion 5 at onesideof the structure,,as indicated at 8. This is done in order to increase the volume inside the casing without adding to the height of that casing. The top of the upper portion 6 is provided with a circular opening 9, and adjacentthis openingthe casing is formed to provide a seat for an annular gasketlfl. A circuit opening is also provided in the bottom of the'lower section 5, and is generally defined by a depending flange 11. Welded or equivalently secured to the casing bottom and the flange llis an inside 'upstandingcylindrical partition 12, shaped at its lower-end to conjointly' form a seat with the flange 11 for.a gasket 13. "The gasket rests upon the aforesaid carburetor flange 2, while the depending flange 11 circumscribes the carburetonflange, as clearly seen in Fig. 2, when'the cleaner-silencerassembly is mounted in position over. the upper portion of the carburetor.

Secured to the upper end of the partition 12 is an annular cup-like shell having a deviated bottom 14 and an outer cylindrical wall 15, forming a container for a cleansingjliquidsuch as crankcase oil for the air cleaning part of 'the structure. The deviated bottom portion of this shell atits juncture with the partition 12 is also shapedto providea seat for an annular gasket 16.

"A c over 17"is provided :for the top of the casing, and

secured to the outer rim of this cover by a lock seam 18 or equivalentlyis a depend ing filter holding shell 19, the bottom of which is turned inwardly and joined to an inner shell20; concentric with the shell 19 but spaced therefrom to *define a compartment therebetween for a filter mass or element 21'0f any-suitable material, such as curled cattle tail hair. 'One or more depending feet 22. are secured to the-underside of the cover and abut against the curvature upper-endof 'the inner shell' 20'to lend stability to the stfllcture andto insure positive engagement of thefilter holding means with;the gasket16 whenthe cover together with the'entire filter-element is positionedon the casing, the lockseam ofthecover resting on the aforesaid gasket 10=atthetopof thecasing. The cover is held in position on' the-casingby means-ofa bolt 23 secured to the upper portion of thecarbureto'r, and whichextends through a suitable aperture in the covertobe engaged by a wing nut 24- externally of the-cover.

:T he composite -=fllter-holding shell made up of the elements 19 and has .enlarged openings in the bottom thereof as indicated -at-25,-and over those openings an internal screen 26 may be'located,-if so desired. This filter holding shell also carries a baflle 27 secured to the bottomthereof,whichbaffle extends down into the liquid containerto meter the-amount of liquid carried into the filter mass by traveling 'air, during operation.

Theinner-element 20 of the filter holding shell-conjointly :Withflle partition 12 forms a housing for the upper portion. ofthe carburetor 'above the flange 2,-an'd also acts, of course, as the outlet conduit for clean air. It will also be noted that there is an annular passage 28 between the outer element 19 in the filter holding shell and the vertical wall 15 of the liquid cup through which air descends toward the liquid in the bottom of the cup member.

Now it will be noted that the entire interior of the casing comprising the

portions

5 and 6, outside of the partition 12, the vertical wall 15 of the liquid cup, and in the upper portion outside the outer wall 19 of the filter holding shell, is all one volume chamber This volume chamber is, as shown, preferably of a size sufiicient for the attenuation of a wide band of sound waves of different wave lengths or frequencies. Of course, this volume chamber is in open communication with the annular air inlet passageway 28 leading toward the liquid in the bottom of the cup. In order to tune this large volume chamber to a predetermined frequency or narrower band of frequencies, we have provided a simple partition element 29 in the upper part of the casing, the lower end of the element being secured to the inside of the outer casing wall, and the upper end of the element being secured to the casing adjacent the top opening. The partition is arcuate in shape and its intermediate portion is disposed opposite an opening in the casing wall in which a dirty air inlet duct 30 is mounted. It is not essential that a conduit or duct 30 be utilized, but it is preferable in order to eliminate the possibility of debris lodging inside the casing, as might be the case if a bare opening were provided.

The partition 29 therefore forms a double branched tuning tube, or, in a manner of speaking, a pair of tuning tubes or channels extending in opposite directions but having a common junction with the inlet 30. As seen in Fig. l, in the illustrated embodiment, the branches or

separate tuning tubes

31 and 32 formed by the partition 29 are of equal length terminating at their open ends 33 and 34, respectively. It is not essential that the branches or

tubes

31 and 32 be of equal length measuring from the center line of the inlet 30, because under certain circumstances it might be desirable to vary the lengths of these tubes in order to effect a desired tuning of the volume chamber. To that end, in Fig. 1, we have indicated other points of termination such as 33a for the

tube

31, and 34a for the tube 32, in which event the tube 31 would be noticeably longer than the tube 32. The tubes or

branches

31 and 32 may be shortened as much as desired, and lengthened substantially as much as desired, it being only necessary that there be room between the open ends 33 and 34 of the tubes to discharge the proper amount of incoming air and without interference or turbulence between the air streams. But only in rare cases will it be necessary for the tubes to pass beyond the diametral plane through the bolt 23 which is the center of the air cleaning structure since there is a tremendously wide variance of frequencies for the volume chamber that may be acquired with tubes of less length.

It should be especially noted that with the instant arrangement adequate tuning of a volume chamber incorporated in an air cleaner-intake silencer assembly of the character that fits over the upper portion of a carburetor, is provided by way of the tuning tubes or

branches

31 and 32, and no increase in overall size of the casing is necessary, since these tubes are inside the volume chamber itself.

Now in operation, incoming dirty air enters the inlet 30, substantially divides itself into two streams passing through the

tubes

31 and 32, and discharges directly into the volume chamber. The air descends through the annular passage 28, contacts liquid in the bottom 14 of the liquid cup member, passes upwardly through the filter mass 21, and enters in a clean and dry condition inside the enclosure formed by the inner wall 20 of the filter shell and .the partition 12, whereupon the air may enter the carburetor directly in the region of the opening or openings controlled by a choke valve. Noises emanating from the engine will exit through the opening or openings controlled by a choke valve, pass reversely through the filter element and the sound waves upon reaching the bottom of the passage 28 will be in communication with the tuned volume chamber. The structure of the instant invention is such that sound frequencies over a relatively wide range will be attenuated with the volume chamber tuned for a single frequency. For example, if the volume chamber is tuned to a frequency of 98 cycles per second, it has been found that it effectively silences any sound emanating from the engine and having a frequency between 103 and cycles per second. Thus, it will readily be seen that the same cleaner-silencer assembly may be used on several different automotive engines, without even a minor change therein.

At present, one theory of operation of the instant invention is that the double-branched tuning tube or channel forms an acoustical short circuit for the volume chamber, in that the impedance to sound waves at the air inlet opening is far greater than the impedance to sound waves in a direction from one tube branch into the other. Tests have not definitely proven this theory correct, but conversely have indicated no real error in it.

In most cases the main sound to be attenuated is the fundamental engine tone, commonly referred to as power roar. With the volume chamber tuned to attenuate or neutralize that particular tone, it will automatically neutralize one or more harmonics thereof, as well as other tones within a reasonable range on either side of the frequency of that tone, and in the case of the instant invention, that range is definitely Wider than with any resonator attenuating chamber heretofore known. That fundamental engine tone is to be distinguished from the rather sibilant hissing noise of suction in the engine, which hissing noise is effectively eliminated or absorbed by the filter element 21 itself which, in the case of the instant invention, accomplishes the same result as hiss pads heretofore used inside the cover of the casing. But with the instant invention, that hiss pad inside the cover may be eliminated since with the sound waves directed reversely through the filter element, the filter element performs that additional function.

By way of example, and not by way of limitation, it may be mentioned that with a cleaner-silencer assembly as seen in Figs. 1 and 2, and having an overall longer diameter of 16 inches, exclusive of the inlet duct 30, a tuning tube of a 25 inch length symmetrically mounted With respect to the inlet, that is to provide two oppositely disposed tubes 12 /2 inches each in length effectively tuned the entire volume chamber to a frequency of 98 cycles per second.

Now the tuning of the volume chamber may also be effected by shifting the tuning channel or strictly speaking shifting the position of the partition 29 so as to render it unsymmetrical with respect to the inlet. In this regard, by Way of example, for the same assembly a 25 inch channel was arranged unsymmetrically, and it tuned the volume chamber to a frequency of 107 cycles per second, so that by merely making the channel unsymmetrical, the frequency was varied from 98 to 107 cycles per second. There is another important feature that should be carefully noted in connection with the instant invention. That is that the volume chamber may be tuned to two widely different frequencies. Again, by way of example and not by way of limitation, it was noted that the 25 inch channel arranged unsymmetrically not only tuned the volume chamber to a frequency of 107 cycles per second, but also brought in an additional definite tuning to a frequency of 295 cycles per second. It was further found that with this particular size assembly complete removal of the partition 29 resulted in the chamber being tuned to 133 cycles per second and also to a second frequency of 310. When the channel was 18 inches in length, symmetrically arranged, thereby providing two tuning tubes of 9 inches each, the chamber was found to be ll l diQl,..Q $.P 99. l and, a s ond. tre eacy otjzes; anda.. ZHiI hQha meL symm tis tfiisa l uni drthe chamber tit-. 92. cysl sr r .Q nd.aeqi .nd frequency of 260. v A 6 inch channel symmetrically arranged .andopen at both ends, as were all the other tests, tuned. the volume chamber to 112 cycles .per secontijwith a second frequencyof 2 62,,cyclesper second.

It will therefore b e'.especially inoted thatlwhen necessary, and manyengines give forth. two;relative1y 'posit ive tones .at widely' spaced frequencies;thegsingle volurne chamber may betuned 'to neutralize. shund waves oftwo widely. spaced frequencieslat thejsametirne." -That .is a very valuable attribute of ,the instant ntion because in the past difiiculty has been experiencedflw th lso ne silencers having true resonator chalhibrgbecaus where the resonator chamber was effective to attenuate the predominantlenginetone, another secondary tone then became noticeable.

Now it will be noted that inorder to efiect adequate tuning of the volumechamber it is simplylnecessary. to either vary the length or ,shift theposition of the partition 29, a mosteconornica l procedurein thecourse oi manufacture of the assembly.

Tests were alsomade with one end of: the tuning channelblocked, and while vthistuned the.volume chamber properly to a desired frequency or frequencies, it tends to raise the restriction ofQthe apparatus to entering air. This is indicative of the fact that a tuning channel with bothends open is .mOre desi abIe but not absolutely essential.

In Fig. 3. we have illustrated aslightly different form of construction which may b'e desirable where a little less volume in the attenuating chamber is desired, and a structure which is-somewhat moreeconom-ical thanthat seen in Figs. 1 and 2. in this instance, the structure is the same as above described except for. two minor variations. The first variation is in the fact that the bafiie 27 andlower part of the filter holding shell are arranged to carry the gasket 16, and thelbottom 14 of theliq uid cup-is brought inwardly and curved upwardly as indicated at 35 to bear against that gasket. The second variation'is'the elimination of the partition 12, and the substitution of afsloping partition 36. which is. spot welded or equivalently secured to an intermediate portionof thebrottom 14 of the oil cup at its upperend, and at it'slower end is secured to .the overalhcasingbottom adjacent the point where that casing bottorn is shapedto accommodate the gasket 13. The structuredisclosed in Fig. 3 operates in all respects" identical with the. structure shown irrFigs. 1 and 2, with the single exception that the volume of the attenuating chamber is slightly reduced owing to the dilferent shape of the partition 36 frornth'atof the partition 12.

In Figs 4 and 5 we have illustrated ajorm of construction that differs-from that previously disclosed irrthat the tuning channels or tubes. are disposed on the, outside of the main casing, and also by..the factthat in servicing the air cleaner, the top together with. the, filter element may first be removed, then treliquid a cup lifted out of the main casing whichmay remain in position on the flange of the carburetor. In this instance, theupper portion 6 of the casing is solid opposite the inlet duct 30 as indicated at 37. A channel-shaped member 38 is secured to the outside'of the casing wall to form the opposed tuning channels, and in an intermediate point that channel is provided with a flanged opening as indicated at 39 to receive the inlet, ductiii. The ends of the side branches 4t) and 41 of the tuning tube member 38 communicate with the interior of the casing by way of elongated slots 42 (Fig. 5) cut in the wall of the upper casing portion 6, both ends of the channel member 33 itself being externally closed as indicated ate} in Fig. 4. As was the case with the embodiment described in coninection with figs. 1 and 2 it is not essential that the tubes or branches'4t} and 41 be'of'the same length, but

theynmy terminate at difierent portions, as indicatively th ws tfiti t dl li ss i ni i .tj t Pai e sou 1 or at ethetroint dpendingyroe D niel rquen siredi or, he

In" this instance, also, the gasket 16 upon which the filter holding shell seats, is held by aformatio'nin the A n0tthe;b ttom-,1 4 ofrthefliquid cup as described'in. 'nnectionwith Fig; '2, but there is no. vertical partition 12. L lnlieiivthereof; therehis asl oping partition 44 secured in twopla cestto the bottom .14 of the liquid cup as indicated at 4 5. and toinsure adequatestrength and rigidity .The lower portion of this partition is chanholed inwa rdly to hold'an agai st gasket 41 which seats against th bat e s ithas nau s e pa ti o 44 m n te i aflat s r3 1d n d w w y W t e se t; fo the ske 3. f rm n the casing bottom, but is notseeured .tqthe casing bottom.

A prsiin ynw mth slea e nfF sand 5 i to be serviced, it is a simple e xpedient to remove the wingnut -24, lift off the eovmyl'l c arrying the filter unit..therewith, then-lift out the-liquid .cup 14-15 together with the partition 44. and gasket47, leaving .thecasing proper seatedon thegfiangel. of. the c arburetor.. .With. this arrangement it is simpler to empty the cleasisingliquid and accumulated .dirt from the liquid .cup,.. refill it. with. .new cleansing liquid replace it, and set..the cover with the filterunitin..position,\.then tighten down the wing nut 24. to clamp' all..parts firmly in place and in sealing engagement with each other. T Otherwise-the.structureoffigs. 4' and 5, insofar as sound attenuation isconcerned, -iunctions the same as structurespreviously,described;'It' will be noted, also, 1hat---the -disposition of the tuning tube on the outside of the; casing, rather than Qin'side, adds hut a negligible amount to theoverall size of the entireassembly.

- ln 'Fig-w'e have illustrated'a still different form of structure which aybe more convenientfo r certain installations; but which functions insofar;as airicle aning andsilencing ste med are same manner fa s the structure seen in-jh igs. land 2; 7 l-lowevenijn this instance ent pp r po o of. t e re i s fr mo a e al with theqfilter element of th rf cleaner when servicing is needed To end, it will benoted that the upper marginal part of the lowerportion 5 of the casing is channeled as indicated z t-48 to forrn a seat for a gasket 49, which .ga sket and channeling extend entirely, around this lower portionof thecasing. The upper portion of the casing, here designated oa, has integral with it a cover portion Edgar-id ithis gupper po'r'tion is not lock seamed to,thejower portion, but the lower edge of the' uppenportion an i's-froll'ed orbeaded as at 50 entirely ,therearound to seat onthe gasket 49. The outer wall 19 of the filter holdingshell is spot welded or equivalently secured tothe inside of the top part. of the upper portion 6a, rather thanheing were amed to theseparate cover 17 described infcohnectiori .wi tli Figs. 1 and 2.

v:With thefarr aiigemerit: of :Fig l 6, when servicing is reiq retileai he .u n inl t ltisfr m v t e entire upp portion; of the overallcasir g is lifted off the gasket 49, carrying the entire filterelement therewith; The lower portion 5 of the icasing may then be lifted otf the carburetor flange Zandthe dirty liquid dumped from the liquid cup 1415. Preferably, the air inletduct 30 is c'arriedby the upper portion 6a of the overall casing.

.Whilean air cleaner-silencerassembly constructed in various .siz'esand inhccordaneewithone ofthe structures hereinbefore explained ishighly efficient and satisfactory ior cleaning incoming air and effecting: intake silencingfor substantially any internal combustion engine, one unusually rare and unique situation with a particular automobile engine has been noted. "All'atternpts toiefiectively" silence that particular engine by silencingimeans heretofore known and made infa size to fit the 'allowable space proved inetfective until Ltheadventof the instant asaasas invention. The explanation for the distinctly and curiously peculiar sound production from this individual engine appears to be that the engine developed a relatively deep tone other than the fundamental tone, and that the intake manifold, providing a constant volume, was inadvertently and unintentionally constructed so as to be tuned to this other tone and function as a Helmholtz amplifying resonator upon the opening of the intake valve to a cylinder. Such unexpected amplification of the second engine tone, in effect made that tone the predominant one, and it obviously would be particularly significant when the fundamental tone was silenced. Whether or not that second amplified tone was of the frequency sufficiently close to the fundamental tone to be effectively attenuated by any of the structures illustrated in Figs. 1 to 6, inclusive, is of no moment, since the unexpected strengthening of the tone by amplification apparently rendered it irresistible to joint silencing along with the fundamental tone.

However, even this singular but objectionable phenomenon was effectively overcome by a slight modification of the instant invention, illustrated in Fig. 7. The general structure is substantially the same as shown in Figs. 1 and 2. In this instance, however, there is an added partition 52 which has a marginal portion secured in the lock seam 7 entirely around the casing, and the inner marginal portion spot welded or equivalently secured to the wall 15 of the liquid cup 14-15, as indicated at 53. This partition, therefore, effectively divides the lower portion of the overall volume chamber into a separate true resonator chamber 54 which, in the illustrated instance, comprises all of the contents of the lower portion of the casing, and a part of the volume within the upper portion 6. The resonator chamber 54 is acoustically coupled to the path of sound waves emanating from the engine through the carburetor by means of a series of apertures or openings 55 in a partition 12a which corresponds to the partition 12 described in connection with Pig. 2, but which in this instance has an outwardly turned margin secured to the bottom of the casing. Preferably, a tuning skirt 56 is also utilized to define a passageway 57 between itself and the partition 12a, the tuning skirt being concentric with the partition 12a, but having a flared upper end so that it may be secured to the wall 12a at the top. The lower end of the tuning skirt or tube 56 is merely open. Varying the width of the passage 57 and lengthening or shortening the skirt or tube 56 effects desirable tuning for the resonator chamber 54.

With this arrangement, the amplified tone emanating from the engine is at once attenuated by the resonator chamber 54, and the sound waves of this tone do not reach the filter element 21 and ultimately the main volume chamber in the upper part of the casing. The main volume chamber above the partition 52 attenuates other tones from the engine and is tuned by the branched tuning tube formed with the partition 29, in the same manner as above described in connection with the showing in Figs. 1 and 2.

From the foregoing it is apparent that we have provided an air cleaner-intake silencer assembly of a character that will house or receive therein the major portion of the carburetor, and yet which may be effectively, easily, and economically tuned over a great range of sound frequencies without altering the overall dimensions of the structure. Further, it will be apparent that we have provided an intake silencer of a new type which attenuates a greater range of sound frequencies upon a single tuning than was heretofore possible, and which also may be tuned to more than one sound wave having frequencies widely apart. The instant invention also eliminates the need of the hiss pads formerly used inside the covers of silencer or air cleaner arrangements, and effectively and economically, by a simple change in construction, may be made to neutralize or attenuate even it) totally unexpected engine noises. The entire assembly is even more economical than assemblies of similar character heretofore known, possesses many more advantages, is highly durable, and easily installed and serviced.

It will be understood that modifications and variations may be elfected without departing from the scope of the novel concepts of the present invention.

We claim as our invention:

1. An air cleaner and intake silencer assembly, including a casing having a clean air outlet opening through which sound waves to be attenuated enter the casing, air cleaning means in said casing, means sealing off said outlet opening except by way of a path through said air cleaning means, said casing extending laterally well beyond said air cleaning means to define a volume attenuating chamber disposed substantially around said air cleaning means and sized for the attenuation of sound waves of dilferent frequencies, said casing having an inlet opening, and tuning tube branches communicating with and extending both ways from said inlet opening with their outer ends opening into said chamber, incoming air passing through said tube branches, said branches being sized to tune said chamber for attenuation of a predetermined range of sound frequencies.

2. An air cleaner and intake silencer assembly, including a casing having a clean air outlet opening through which sound waves to be attenuated enter the casing, air cleaning means in said casing, means sealing off said outlet opening except by way of a path through said air cleaning means, said casing extending laterally well beyond said air cleaning means to define a volume attenuating chamber disposed substantially around said air cleaning means sized for the attenuation of sound waves of diiferent frequencies, said casing having an inlet opening, and a plurality of tuning tubes for said chamber carried by said casing, said inlet opening leading to said tuning tubes only, and the free ends of said tubes opening into said chamber, said tubes being sized to tune said chamber for the attenuation of sound waves of a predetermined range of frequencies.

3. An air cleaner and intake silencer assembly, including a casing having a clean air outlet opening through which sound waves to be attenuated enter the casing, air cleaning means in said casing, means sealing olf said outlet opening except by way of a path through said air cleaning means, said casing extending laterally well beyond said air cleaning means to define a volume attenuating chamber disposed substantially around said air cleaning means sized for the attenuation of sound waves of difierent frequencies, a channel shaped member secured to the wall of said casing to define with said wall a tuning tube for said chamber with both ends thereof opening into said chamber, and said casing having an inlet for contaminated air which opens into an intermediate part of said tuning tube, said tuning tube being sized to tune said chamber for the attenuation of a predetermined range of sound waves.

4. In an air cleaner and intake silencer assembly, a casing having an air outlet opening in the bottom of a size to receive the upper portion of a carburetor, said casing having an opening in the top thereof, a removable cover for said top opening, annular air cleaning means beneath said cover, means sealing off said outlet opening except to air passing through said cleaning means, said casing defining therein a volume sound attenuating chamber in open communication with said cleaning means and sized for the attenuation of sound waves of different frequencies, a tuning tube for said chamber carried by the casing and extending along the wall of said casing a predetermined distance and opening into said chamber, and said casing having an air inlet opening into an intermediate part of said tube, said tube tuning said volume chamber for a predetermined range of sound frequencies.

5. An air cleaner and intake silencer assembly, comprising a casing enclosing a volume chamber sized for attenuating a relatively wideband of sound waves, said casing having an air inlet opening and an unimpeded air outlet opening,. means defining a path of travel; for

air 'through the casing, filter means in said path, said E'path and said filter means communicating directly with {and said path forming a part of said volume chamber inside said casing, said path definingmeans including tuning tube means carried by said casing and communicating directly with said air inlet opening at an intermediate point and extending both ways therefrom with the ends thereof opening freely into said chamber, said tuning tube means being sized to tune said chamber for the attenuation of a predetermined narrower band of sound waves.

6. An air cleaner and intake silencer assembly, comprising a casing enclosing a volume chamber of predetermined size relatively to sound waves to be attenuated therein, air cleaningmeans in said casing, said caslng communicating abruptly with the confronting ends of said channels.

7. An air cleaner and intake silencer assembly, comprising a casing enclosing a volume chamber of a predetermined size relatively to sound waves to be attenuated therein, air cleaning means in said casing, said casing -having a free and unrestricted outlet opening for clean air leading from said air cleaning means and through -which sound waves to be attenuated enter said volume chamber, means carried by said casing defining a doublebranched tube open at the free ends for free and unimpeded communication with said chamber, and said casing having an air inlet opening abruptly into the junction of the tube branches at an angle exceeding 45 between the axis of the inlet and the axis of the tube, whereby the impedance to passage of sound waves outwardly through said air inlet is far greater than the impedance in a direction from one branch ofsaidtube toward the other.

'8. An air cleaner and intake, silencer assembly,- comprising a casing enclosing a volume .chamber sized for the attenuation of a relatively wide band of sound .waves of different frequencies, said casing having an air inlet -opening and anair outlet opening, air cleaningmeans includinga filter in said casing, meanssealing offsaid outlet opening except by way of a path through said air cleaning means, said path communicating directly with'said volume chamber inside said casing, and tuning tubes carried bygsaid casing and communicating with and extending. both ways along the casing wall from-said inlet opening with their separated ends opening into said chamber, said tubes being sized to tune said volume chamber forthe attenuation of a predetermined narrower band of sound Waves.

9. An air cleaner and intake silencer assembly, comprising acasing enclosing a volume chamber sized for the attenuation of a relatively wide band of sound Waves of different frequencies, said casing having an air inlet opening and an air outlet opening, air cleaning means including a filter in said. casing, means scaling 015? said outlet opening except by Way of a. path through said air cleaning means, said path communicating directly with .said volume chamber inside said casing, and means connected to the wall of said casing defining a channel in 'open communication with and extending sidewise both ways frornsaid inlet opening with the ends of the channel I. 1 opening. into said volume chamber, said channel be1ng of .a device needing an air supply, comprising a casing defining av volume chamber therein sized for the attenua= tion of a predetermined relatively wide band of sound waves, said casing having an opening for the discharge of air and through which sound waves from the device enter the casing, and a tuning tube carriedby said casing with both ends thereof opening into said chamber, 'said casinghaving an air intake openingleading 1nto an intermediate partof said tube, and said tube be1ng other- 15 wise imperforate and sized to tune said chamber for the attenuation ofa, predetermined narrower band of sound wavesysaidtube, being longer on one side of said air volume attenuating chamber With which said air clean- 7 ing means are in open communication and which chamber is sized to attenuate a predetermined relativelywide band of sound waves, tuning means for said chamber 7 carried by said casing and sized to tune said chamber for the attenuation of a predetermined narrower band 7 of sound waves, said tuning means forming a flow passage open at both ends and entirely independent of said chamber, and said casing having an inlet for contami- ;nated air opening directly into the flow passage formed by said tuning means intermediate the ends thereof.

12. An intake silencer for connection with the intake of a device needing an air supply, comprising a casing .defining a volume chamber therein sized for the at- .tenuation of a predetermined relatively Wide band of sound waves, said casing having an opening for the discharge of air and through which sound waves from the device enter the casing, a tuning tube carried by said casing with both ends thereof opening into said chamber,

said casing having an air intake opening leading into an .intermediate part of said tube, and said tube being other- WlSB imperforate and sized to tune said chamber for the attenuation of a predetermined narrower band of sound waves, said casing being cylindrical, and said tuning tube being longitudinally curvate to follow the, curvature of the cylindrical casing withradii from the open ends of 50 the tube defining an angle of at least which, angle includes the tube itself.

13. An intake silencer for the intake of a device requiring an air supply comprising a casing having an air inlet opening in the wall thereof, said casing enclosing a volume chamber of; sufiicientsize for the, attenuation of arelatively Wide band ofwsound. waves, partition means,in said casing defining withthe inside of'the casing Wall tuning channels opening freely into said volume ;chamber and extending in opposite directions ina lateral plane from saidinletopening and incommunication with said inlet opening, the adjacent: ends. of said-channels ,confronting each other at saidinlet opening to in effect -and conjointly define a path fortsound waves substantially at rightangles to-theair path through said inlet opening, said channelsbeing sized to tune said volume chamtrance of sound waves to be attenuated.

'14; An intake silencer for connection with the air intake. of an internal combustion engine, comprising a casing enclosing a-volume attenuating chamber of sufiicientrsize for the attenuation of a relatively wide band of, sound waves, said casing having an airinlet opening, and tuning means communicating at a point intermediate the ends thereof with said opening and defining flow passages for incoming air extending in different directions from said opening, said flow passages opening freely and unimpeded into said'volume chamber, said flow passages being sized to tune said volume chamber for the attenuation of a narrower band of sound waves, said casing having an unimpeded outlet opening for the discharge of air and through which sound waves to be attenuated enter the casing in opposition to the direction of travel of air, and connecting means to connect the silencer with the air intake of an engine with said outlet opening communicating with the opening in the engine air intake.

15. An air cleaner and intake silencer unit, comprising a casing having a clean air outlet opening and through which sound waves to be attenuated enter the casing, air cleaning means in said casing communicating with said outlet opening, said casing defining an interior volume attenuating chamber with which said air cleaning means are in open communication and which chamber is sized to attenuate a predetermined relatively wide band of sound waves, tuning means for said chamber carried by said casing and sized to tune said chamber for the attenuation of a predetermined narrower band of sound waves, said tuning means forming a flow passage entirely independent of said volume chamber and with both ends communicating with said chamber, and said casing having an inlet for contaminated air opening directly into the flow passage formed by said tuning means intermediate the ends thereof, and means cooperating with said casing to define a resonator chamber in addition to said volume chamber, said resonator chamber having an acoustic coupling to permit entry of sound waves entering said casing.

16. An intake silencer for association with the intake of a device needing an air supply, comprising a casing having an air outlet opening and an air inlet opening spaced therefrom, said casing defining a volume attenuating chamber therein in open communication with said openings and sized for the attenuation of sound waves of different frequencies, a conduit extending into said casing around said outlet opening, means in said casing defining a flow path for outgoing air through said conduit, and partition means in said casing cooperating therewith in defining and sealing off a resonator chamber around said conduit which is closed except for an acoustic coupling between the path through said conduit and said resonator chamber, and tuning tube means carried by said casing for said volume chamber.

17. An intake silencer for association with the intake of a device needing an air supply, comprising a casing having an air outlet opening and an air inlet opening spaced therefrom, said casing defining a volume attenuating chamber therein in open communication with said openings and sized for the attenuation of sound waves of different frequencies, a conduit extending int-o said casing around said outlet opening, means in said casing defining a flow path for outgoing air through said conduit, partition means in said casing cooperating therewith in defining and sealing off a resonator chamber around said conduit which is closed except for an opening in the wall of said conduit to establish an acoustic coupling with said resonator chamber, a tuning tube for said resonator chamber concentric with said conduit, and tuning means carried by said casing for said volume chamber.

18. An intake silencer for association with the intake of a device needing an air supply, comprising a casing having an air outlet opening and an air inlet opening spaced therefrom, said casing defining a volume attenuating chamber therein in open communication with said openings sized for the attenuation of sound waves of difierent frequencies, a conduit extending into said casing around said outlet opening, means in said casing defining a flow path for outgoing air through said conduit, partition means in said casing cooperating therewith in defining and sealing off a resonator chamber around said conduit which is closed except for an acoustic coupling between the path through said conduit and said resonator chamber, a tuning tube for said resonator chamber concentric with said conduit adjacent said acoustic coupling, and tuning means carried by said casing for said volume chamber.

19. In an oil bath air cleaner assembly a housing en-- closing an oil sump and filter element, an annular inlet in the housing for dirty air, a silencer chamber surrounding the housing and enclosing the annular inlet, an air inlet orifice in the silencer chamber, a partition in the silencer chamber masking the inlet orifice nad extending a substantial distance on each side of it to provide arcuate tuning tubes, and an outlet in the assembly for clean air.

2-0. in a hat type oil bath air cleaner, an annular housing having an oil sump and filter element concentrically disposed therein, an annular inlet formed in the housing so that dirty air may communicate with the oil sump and filter element, an outlet formed in the housing for clean air, an annular silencer chamber surrounding the housing, the annular air inlet opening into the silencer chamber, the housing forming an annular depression in the silencer chamber, an inlet orifice for the silencer chamher, and inlet tuning channels leading from the inlet orifice a predetermined distance along the sides of the silencer chamber.

21. In a liquid bath hat-type air cleaner and silencer assembly, a filter housing enclosing a liquid sump and a filter medium, an annular inlet in the filter housing for dirty air in communication with the liquid sump and filter medium, a silencer housing around the filter housing defining a silencer chamber with it, the annular inlet in the filter housing for dirty air opening into the silencer chamber, an air inlet orifice on the side of the silencer housing opening into the silencer chamber to provide for the dew of dirty air through the silencer chamber to the annular inlet in the filter housing, an outlet in the assembly for clean air in communication with the filter medium, and an arcuate partition in the silencer chamber conforming generally to the inner surface of the silencer housing and masking the inlet orifice in the side of the silencer housing, the arcuate partition extending a substantial arcuate distance on each side of the inlet orifice and providing inlet tuning tubes leading from the inlet orifice a predetermined distance around each side of the silencer housing opening into the silencer chamber generally on opposite sides of the filter housing.

22. In a liquid bath air cleaner assembly, a filter housing enclosing a liquid sump and a filter medium, an annular inlet in the housing for dirty air, an outlet in the housing for clean air, a silencer chamber around the housing enclosing the annular inlet, and tuning passages around the wall of the silencer chamber of a predetermined length in communication with the outside and opening into the silencer chamber, the tuning passages being generally arcuate and conforming generally to the silencer chamber.

References Cited in the file of this patent UNITED STATES PATENTS