US2078754A

US2078754A - Silencer

Info

Publication number: US2078754A
Application number: US717197A
Authority: US
Inventors: John A Day
Original assignee: CF Burgess Laboratories Inc
Current assignee: CF Burgess Laboratories Inc
Priority date: 1934-03-24
Filing date: 1934-03-24
Publication date: 1937-04-27
Anticipated expiration: 1954-04-27

Description

A April 27, 1937. J. A. DAY 2,078,754

S ILENCER Filed March 24, 1954 2 Sheets-Sheet l NVENTOR fof/7N y April 27, 1937. J. A. DAY 2,078,754

SILENCER Filed March 24, 1954 2 Sheets-Sheet 2 C) /ML/ G O G 0 y uNvENToR JTO/m f7. gay

ATTORNEYS Patented Apr. 27, 1937 UNITED STATES PATENT FFICE Applicationlllareh 24, i934, Serial No. fillldlii'i l5 (Claims.

rl'his invention relates to improvements in silencers, and particularly those used to silence the intakes and exhausts of internal combustion engines, Compressors, pumps and the like. ln particular it relates to improvements in the type of silencer disclosed and claimed in Schnell Patent No. 1,811,762.

lt is an object or this invention to provide an improvement in the construction of a silencer ci the type described whereby the effectiveness thereoi is increased.

lt is a further object of this invention to cornbine a silencer and manifold in such a manner that greatest possible effects are obtained from the silencing means used.

In an exhaust system, gas pulses at high pressure and sounds are both present. Since sound is an alteration in pressure, or a superposition or a number of pressure alterations, propagated in an elastic medium, a sound propagated in gas or air may be called a gaseous-pressure wave. Gas pulses may also be called gaseous-pressure Waves. It is an object of this invention to provide an irn-a proved silencer which attenuates both of the men" tioned kinds of gaseous-.pressure waves. if the gas pulses are not attenuated or altered in form Within the silencer, upon their emergence therefrom they expand into the atmosphere and create sounds. When the attenuation of sound is spokenof herein, it is meant to relate to the attenuation of gaseous-pressure Waves which would otherwise result in objectionable sounds being heard.

I have found that it is possible to incorporate sound attenuating means, e. gl., gaseous-pressure wave absorbing material `ahd/or space-volumes, into a manifold, either intake or exhaust, and thereby eliminate the necessity of employing a silencer remote from the engine. This not only provides a single compact unit replacing two separate units, manifold and silencer, but affords greater silencing for the same size and amount of attenuating means used. In general, the silencing effect is increased if the attenuating means is moved closer to the source of the sounds. Placing the attenuating means adjacent the exhaust ports of the engine allows greater expansion of the exhaust gas at this point than would take place if the usual type of manifold is used. This is particularly advantageous in that the gases are at their highest temperature when they leave the cylinder of the engine and the expansion within the manifold .silencer eiects a greater cooling than is obtained with the usual type of manifold. When the manifold silencer is used as an intake (Cl. limb-fw) silencer, the amount ci attenuating means en posed to the incoming air is considerably greater than it is in the usual types of intake silencers, such as is disclosed in Hartsock United States Patent No. 1,934,463, because of the relatively greater size oi the iorrner.

In the drawings:

Fig. l is a longitudinal sectional vievr or one form of the silencer on line i-i of Fig. 2;

Fig. 2 is a transverse sectional view or" the silencer on line oi Figi. l;

Fig. 3 is a transverse sectional view of a modi cation or the silencer shown in Figs. l and 2;

Fig. l is a longitudinal sectional view of an other forni of silencer on line l-Jl of Fig.. 5;

Fig. 5 is a transverse sectional view or the silencer on line of Fig. ll;

Fig. 6 is a longitudinal sectional view oil a iurther modification of the silencer on line 'il- G ci Fig. 7 is a transverse sectional view oi? the silencer on line i-ll of Fig. 6;

Fig. 8 is a longitudinal sectional view of another form of the silencer on line ll-ii of Fig. 9;

Fig. 9 is a transverseV sectional view of the silencer on line @-9 of Fig. 8;

Fig. l0 is a longitudinal sectional view or a further modification oi the silencer on line iti-iii of Fig. li;

Fig. l1 is a transverse sectional view of the silencer on line il-li or" Fig. 10;

Figs. l2 and 13 are transverse detail views of a portion of the silencer shown in Figs. l and 2; and

Fig. 14 is a diagrammatical illustration showing the silencer mounted upon an engine bloclr.

The silencer shown in Figs. l and 2 consists of an elongated imperforate outer casing i, which may be rectangular in transverse section, as shown in Figi. 2. The casing is provided with end Walls 2 and 3. One longitudinal Wall of casing i is provided with a plurality of openings l in spaced relation. A single opening 9 is provided in end Wall 3. An elongated perforate or foraminous shell 4, of smaller dimensions than casing I, is disposed Within casing I. Shell 4 is provided with

perforated end Walls

5 and 6. One longitudinal wall of shell 4 is provided With a plurality of openings 1 in spaced relation. A single opening 9 is provided in end Wall 6. Shell 4 is mounted within casing I in such a manner that openings I and SYin shell 4 register Withopenings 'I and 9, respectively, in casing I. The shell and casing are preferably in contact along one longitudinal wall and one end Wall as shown in Figs. 1 and 2, but may be in spaced relation. Openings and 'I' and 9 and 9 are adapted to receive conduits 8 and I0, respectively, which provide communication with the volume defined by shell 4. Gaseous-pressure wave absorbing material II is packed in the space between casing and shell 4. The shell need not extend continuously but may be in two or more sections, as shown in Fig. 8.

For engine and compressor intakes, flammable absorbing materials such as cotton, wool, hairfelt, wood fiber and the like may be used, whereas for gas engine exhausts and other hot gases non-flammable absorbers should be used such as steel wool and other metallic wool, exfoliated vermiculite, asbestos fibers, rock wool, pumice, aggregate formed from heat expanded clay or other argillaceous material, and known under the trade-mark Haydite and other loose ceramic aggregates. The aggregates, however, may be bonded together in a manner so as to leave intercommunicating absorbing channels, as described in Jack United States Patent No. 1,921,468.

Openings are spaced so as to allow conduits 8 to be fitted to the exhaust or inlet ports of an engine. Conduits 8 may be provided with integral flanges 8 which may be fastened directly to the engine block. Conduit I0 is adapted to connect with a tail pipe (not shown) when the device is used as an exhaust silencer. When the device is used as an intake silencer on a Diesel type engine, conduit l0 may be left open to the atmosphere, or, if desired, the conduit may be connected to a suitable air cleaning device (not shown). When the device is used as an inta-ke silencer on an internal combustion engine having a carburetor, conduit I0 is connected to the carburetor.

When the device is used as an exhaust silencer, means should be provided to allow free expansion of the shell Within the casing. Openings in shell 4 are preferably larger than openings in casing I. Conduits 8 are rigidly secured to casing and pass through openings Although conduits 8 are shown as extending inwardly a distance only equal to the thickness of the Walls of shell 4, they may project into the volume dened by shell 4. Shell 4 is secured to casing to permit independent movement thereof due to expansion or contraction. As shown, a plurality of openings are provided in the longitudinal wall of shell 4. Bolts 9| pass through openings 99 and the adjacent portions of the wall ofcasing I. Spacing Washers 92, which are smaller in diameter than openings 90, are placed adjacent the inner surface of the wall of casing I. Washers 93, which are considerably larger in diameter than openings 90, are placed between spacing washers 92 and nuts 94 on the ends of bolts 9| inside shell 4. The thickness of spacing washers 92 is greater than the thickness of .the wall of shell 4, thereby allowing the shell to move freely as it expands or contracts. Spacing washer 92 and Washer 93 may be replaced by a single member.

The high pressure exhaust slugs and other gaseous-pressure Waves emerging from the engine and entering the silencer are reduced or attenuated by means of the gaseous-pressure wave absorbing material exposed by the walls of the perforated shell. The perforated shell is placed eccentrically within the outer casing, preferably in such a manner that one end wall and at least one longitudinal Wall of the shell contacts with a corresponding end wall and longitudinal wall of the casing. This type of construction simplifies the fabrication of the silencer, but is not absolutely essential. The use of an eccentric shell within the casing provides certain advantages because of the different thicknesses of the walls of the gaseous-pressure wave absorbing material, as described and claimed in Spicer application, Ser. No. 506,361, filed January 3, 1931 (now Patent No. 2,046,193, granted June 30, 1936).

The use of a porous material within the manifold allows a greater expansion of the gases as they enter the manifold than is possible with the usual type of manifold. The highest temperatures of the exhaust gas in the exhaust system are encountered as the gases leave the cylinder and enter the manifold. By allowing a greater expansion at this point, a greater cooling effect is obtained which also aids in reducing the amplitude of the pressure slugs and pressure waves.

The silencer shown in Fig. 3 is similar in construction to the silencer shown in Figs. 1 and 2. Outer imperforate casing I2 and perforated shell I3 are circular in transverse section. Shell I3 is mounted within casing I2 in a. manner such that one end wall and a longitudinal side of shell I3 is in contact with the corresponding elements of casing I2. Casing I2 and shell I3 are provided with a plurality of registering longitudinally spaced openings I4 and I4. These openings are adapted to receive conduits I5. A conduit corresponding to conduit I0 of Fig. 1 is connected in similar fashion at one end of this silencer. Suitable means may be provided to allow free expansion of shell I3 within casing I2. The space between casing I2 and shell I3 is filled with a gaseous-pressure wave absorbing material I6.

Figs. 4 and 5 illustrate a silencer in which the foraminous shell is disposed concentrically within the casing. However, if desired, the shell may be disposed eccentrically therein. The silencer comprises an outer imperforate casing I`| having end walls I8 and I8. 'I'he end walls may be removably secured to casing by means of screws I1 to allow access to the interior of casing Casing is provided with a plurality of longitudinally spaced openings 20 along one longitudinal wall thereof. In place of the integral shell 4 of Figs. l and 2, I employ a plurality o1' foraminous tube sections I9 and cooperating solid or non-perforated T-shaped members 2|. When the device is used as an exhaust silencer, the temperature of the exhaust gases may be sumciently high to cause failure of a relatively thin perforated shell, such as shown in Figs. 1 to 3. To guard against such failure, the T-shaped members 2| are made of cast iron or equivalent material and are not perforated. The exhaust gases from the cylinders impinge against these cast iron sections. The latter are capable of withstanding the resulting high temperatures.

The closed end sections I9 are rigidly fastened to the adjacent ends 2| of T-shaped members 2|, as by spot welding. The cylindrical leg portions 22 of the members 2| register withl openings 20 and provide communication with the volume defined by members 2| and tube sections I9. Members 2| may be removably secured to casing by means of screws 22 to allow the shell to be removed from casing I`| for cleaning or rebuilding. The ends of tube sections I9 are adapted to fit loosely over the adjacent ends of T-shaped members 2| to provide slip-joints between them. Members 2| are provided with reduced end portions 2| for this purpose. Sufficient play is provided between the ends of tube sections I9 and the transverse shoulders upon the adjacent end portions of T-shaped members 2| to permit longitudinal expansion and contraction of these parts. One or more of the tube sections |9 are provided with openings 24 which are alined with openings 23 in casing I1. Branch pip sections 25 are rigidly secured to tube sections I9 at openings 24 in the sides thereof and extend outwardly therefrom. The ends of pipe sections 25 iit slidingly within collars 23 which are secured to the interior of the side of casing .I1 in registry with openings 23 in said side. This provides slip-joints, )thereby allowing free lateral expansion and contraction of the shell with respect to casing I1. If desired,

openings

23 and 24 and conduits 25 may be disposed on one of the adjacent walls of the silencer. The space between casing |1 and tube sections I9 and T- shaped members 2| is filled with gaseous-pressure wave absorbing material 26.

T-shaped members 2| may be replaced by concentric perforated tube sections |20 and |2I and conduit |22. Tube section |20 is preferably of greater thickness and has larger perforations than tube sections I9 and |2|, and is capable of withstanding the temperatures resulting from the impingement of the hot exhaust gases from the cylinder. Conduit |22 registers with opening 20 and is rigidly fastened to casing I1 at one end and to tube section |20 at its inner end. The ends of tube sections I9 are adapted to fit loosely over the adjacent ends of tube sections |20 to provide slip-jointsgbetween them. Tube sections |20 and |2| may be held in spaced relation by means of spacers |23. When the concentric perforated tube sections are used in place of the solid T-shaped members, the area of the gaseous-pressure wave absorbing material exposed to the gases is greater than the area exg smaller dimensions than casing 21, is disposed within the casing and has two longitudinal walls fastened in contacting relation with two corresponding walls of casing 21. Shell 30 may be irregular in transverse section and may differ in transverse section from casing 21, but it is desirable to have the contacting Walls of the casing and shell of the same shape so as to simplify the assembly operations. Lateral branch conduits 34 are connected to openings 33 in the side of casing 21 and pass through corresponding openings in the contiguous side of shell 30. In the same Way lateral conduit 36 is connected to the adjacent side of casing 21 and passes through an opening in the contacting side of shell 30. Suitable means may be provided to allow free expansion of shell 30 Within casing 21. The space between casing 21 and shell 30 is filled with gaseous-pressure wave absorbing material 31.

The silencer shown in Figs. 8 and 9 illustrates the use of space-volumes or resonating chambers to attenuate the gaseous-pressure waves. The silencer comprises an outer casing 40 which is provided with end walls 4| and 42. One 1ongitudinal wall of casing 40 is provided with a plurality of longitudinally spaced openings 43. A single opening 44 is provided in the opposite longitudinal wall or in one of -the adjacent longitudinal Walls. Opening 44 is adapted to receive a conduit 45. Two

shells

46 and 41 are secured Within casing 40 in spaced relation to each other and to the casing.

Transverse partitions

48 and 49 are secured to the outer ends of

shells

46 and 41, respectively, to form end walls for said shells and also to provide closed space-

volumes

50, 52 and 53 at the ends of casing 40. Transverse partitions 60 are secured to the inner ends of

shells

46 and 41 and extend between the walls of the shells and the walls of the casing. One or more partitions 5| may be provided within space-volumes 50 to divide the volumes into a 'plurality of smaller space-volumes such as 52 and 53. Volume 50 may be filled withV gaseous-pressure' wave absorbing material which is exposed to the gaseous-pressure waves by means of perforations 55 in end wall 49. Communication between space-

volumes

52 and 53 and the interior of shell 46 is provided by openings in end wall 48, such as A,

perforations as shown at 54. The size and number of the space-volumes and of the openings in the end walls are in such proportion that these systems attenuate high frequency sound.

'A plurality of openings 56 are provided along closed space-volumes 6I and 64.. Suitable openings 62 are provided in conduits 59 to provide communication with chambers 6I. The size of openings 62 and space-volumes 6| are in such proportion that these systems attenuate low fre quency sound. The remaining longitudinal walls of

shells

46 and 41 are provided with a plurality of openings 63 to provide communication with space-volumes 64. openings 63 and the size of volume 64 surrounding these longitudinal walls of

shells

46 and 41 are in such proportion that these systems attenuate low frequency sounds. The total number and individual size of the Various volumes may be changed to meet conditions encountered in different engines. Conduits 59 are connected to the ports of the engine and conduit 45 is connected to the exhaust pipe or carburetor. as the case may be. When the device is used as an intake silencer on a Diesel type engine, a suitable air cleaning unit 65 may be fitted to conduit 45. When the device isused as an intake silencer on an internal combustion engine having a carburetor, conduit 45 is connected to the carburetor. When the device is used as an exhaust silencer, suitable means may be provided as previously described, to allow free

expansion o shells

46 and 61.

Figs. l0 and 11 illustrate a silencer which is particularly adapted for use as an intake silencer. The silencer is attached to a manifold 10 which is provided with the usual conduits 1| along a longitudinal wall of the manifold. An opening 12 is provided in one of the remaining longitudinal walls of the manifold. 'Ihe silencer comprises an outer casing 13 having end walls 14 and 14'. Longitudinal wall 16 of casing 13, is

The size and number of provided with an opening 15 which registers an opening 11 which is adapted to receive an air cleaning unit 18. Perforated partitions 19, shaped so as to allow suflicient space for air cleaning unit 18, are rigidly secured to the longitudinal Walls of casing 13 and extend the length of the casing. The spaces between partitions 19 and casing 13 are filled with gaseous-pressure wave absorbing material 80.

Fig. 14 illustrates a manifold silencer ||0 mounted uponl an engine block by means of flanges ||3 on conduits |I2. Flanges ||3 are fastened to engine block at ports H4 by suitable means such as bolts H5. When the device is used as an exhaust silencer, conduit IIS may be connected to tail pipe ||1. When the device is used as an intake silencer on a Diesel type engine, conduit ||6 may be left open to the atmosphere or may be connected to a suitable air cleaning unit such as shown at 65 ln Figs. 8 and 9. When the device is used as an intake silencer on an internal combustion engine having a carburetor, conduit IIB is connected to the carburetor (not shown).

Other changes in design may be made. The number of conduits communicating with the manifold depends upon the number of cylinders in the engine for which the silencer is to be used. A combination of gaseous-pressure wave absorbing material and space-volumes may be used in a single silencer. The number and size of the space-Volumes and the number, size and type of openings to the space-Volumes may be varied to attenuate sounds of any particular range of frequencies.

I claim:

1. A manifold for internal combustion engines comprisingy a substantially imperforate casing, a shell within said casing, the walls of said casing and said shell defining spaces therebetween, said spaces comprising gaseous-pressure wave attenuating means and being acoustically connected to the interior of said shell, said shell having a plurality of openings in the walls thereof, at least one of said openings being connected to the atmosphere, at least some of the remainder of said openings being adapted to be connected to the ports of the engine and providing communication between said ports and the interior of said shell.

2. The manifold of claim 1 in which the walls of said shell are foraminous and the spaces between said casing and said shell contain gaseous-pressure wave absorbing material.

3. The manifold of claim 1 in which a portion .of the walls of said shell is foraminous and gaseous-pressure wave absorbing material is exposed in the walls of said foraminous portion of said shell.

4. An exhaust manifold for internal combustion engines comprising a substantially imperforate casing, a shell within said casing, the walls of said shell and said casing defining spaces therebetween, said spaces containing gaseous-pressure wave absorbing material, a wall of said shell having openings therein, conduits passing through said casing and adapted to connect said openings with the exhaust ports of the engine and providing communication between said exhaust ports and the interior of said shell, the portions of the wall of said shell opposite said openings being imperforate, at least a portion of the remainder of the walls of said shell being foraminous.

5. A manifold for internal combustion engines comprising a substantially imperforate casing, a foraminous shell within said casing and defining spaces therebetween, means for mounting said shell within said casing in relatively movable relation to said casing whereby said shell may expand freely with respect to said casing, gaseouspressure wave absorbing material in said spaces, and a plurality of conduits communicating with the inner volume defined by said shell, some of said conduits being adapted to be connected to the ports of the engine.

6. A manifold for internal combustion engines comprising a substantially imperforate casing, a perforated shell within said casing and spaced from at least two longitudinal walls thereof and defining spaces therebetween, means for mounting -said shell within said casing in relatively movable relation to said casing whereby said shell may expand freely with respect to said casing, gaseous-pressure wave absorbing material in said spaces, and a plurality of conduits communicating with the interior of said shell, some of said conduits being adapted to be connected to the ports of the engine.

'1. An exhaust manifold for internal combusi tion engines comprising a substantially imperforate casing, a shell within said casing, the walls of said shell and said casing defining spaces therebetween and having a plurality of corresponding openings therein, gaseous-pressure wave absorbing material between said shell and said casing, conduits connecting corresponding perforate and of relatively increased heat resistance, the remainder of said tube sections being foraminous.

8. A silencer comprising an elongated casing, an elongated perforated shell disposed therein, said casing and said shell each having a plurality of corresponding openings spaced along one amar/ta longitudinal wall and at least one corresponding opening in one of the remaining walls, said shell and said casing being fastened together along said longitudinal walls, conduits passing through said openings and providing communication between the exterior of said casing and the interior of said shell, and gaseous-pressure wave absorbing material filling the space between said casing and said shell.

9. In a device of the class described, a substantially imperforate casing having a plurality of openings therein, a shell within said casing and in spaced relation thereto, said shell comprising a plurality of sections fitted together in nonadherent, end-to-end relation, some of said sections being cylindrical, the remainder of said sections being T-shaped and having cylindrical cross and leg elements, said leg elements being fastened to the interior surface of said casing and forming the means for spacing said shell from said casing, the interior of said leg elements registering with said openings, and gaseous-pressure wave attenuating means in the space between said shell and said casing and acoustically connected to the interior of said shell.

10. In a device of the class described, the combination of an outer substantially imperforate casing, an inner shell within said casing and spaced `from said casing, said shell and casing having corresponding openings in corresponding walls thereof, a plurality of conduits disposed in spaced relation along one longitudinal wall of said casing and at least one conduit on one of the remaining walls of said casing, said conduits connecting said corresponding openings and providing communication between the exterior of said casing and the interior of said shell, and sound attenuating means acoustically connected to the interior of said shell.

11. A silencer comprising an outer imperiorate casing, end walls for said casing, a shell having end wallswithin said casing and spaced from at least two longitudinal walls of said casing, said shell and casing having corresponding openings in corresponding walls thereof, a plurality of conduits spaced along a longitudinal wall of said casing, at least one conduit disposed on one of the remaining Walls of said casing, said conduits connecting said corresponding openings and providing communication between the eX- terior of said casing and the interior of said shell, and sound attenuating means between said casing and said shell and acoustically connected to the interior of said shell.

12. A silencer comprising an imperforate casing, a shell having smaller dimensions than said' casing disposed therein, said casing and shell each having a plurality of corresponding openings in one corresponding wall thereof, a plurality of conduits connecting said corresponding openings and providing communication between the exterior of said casing and the interior of said shell, and a plurality of space volumes between said casing and said shell, some of said space volumes being acoustically connected to said ducts and some being acoustically connected to the interior of said shell, said casing having an additional opening in the wall thereof and communicating with the interior'of said shell.

13. A silencer comprising an imperforate casing, a shell disposed therein, said casing and shell each having a plurality of corresponding openings in one corresponding wall thereof, a plurality of conduits connecting said corresponding openings and providing communication between the exterior of said casing and the interior of said shell, and a plurality of space volumes between said casing and said shell, said space volumes being acoustically connected to the interior of said shell, said casing having an additional opening in the wall thereof and communicating with the interior of said shell.

14. A manifold for an internal combustion engine comprising an imperforate casing, a shell disposed in said casing, said shell and said casing having a plurality of corresponding openings in one corresponding wall, and having at least one corresponding opening in another corresponding wall, some of the walls of said casing andr said shell being spaced from each other, and sound attenuating means arranged in said spaces and communicating with the interior of said shell.

15. A device in accordance with claim 14 whereinsaid shell is mounted in said casing to permit expansion and contraction of said shell in said casing.

JOHN A. DAY.