CA1245566A - Compact, sound-attenuating muffler for high- performance, internal combustion engine - Google Patents
Compact, sound-attenuating muffler for high- performance, internal combustion engineInfo
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- CA1245566A CA1245566A CA000487580A CA487580A CA1245566A CA 1245566 A CA1245566 A CA 1245566A CA 000487580 A CA000487580 A CA 000487580A CA 487580 A CA487580 A CA 487580A CA 1245566 A CA1245566 A CA 1245566A
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Abstract
COMPACT, SOUND-ATTENUATING MUFFLER FOR HIGH-PERFORMANCE
INTERNAL COMBUSTION ENGINE
by RAY T. FLUGGER
ABSTRACT
A compact, sound-attenuating muffler for a high-performance internal combustion engine is disclosed in which the muffler casing (21) has an elongated transverse cross-section with a height dimension of only slightly larger than the height dimension of the inlet exhaust pipe (22) and a width dimension in the range of about 2 to 4 1/2 times the height dimension, The muffler includes a divergently tapering planar first partition (36) which causes gases to be expanded only in a horizontal plane toward the side walls (38,39) of the muffler and further includes a second partition (41) formed to contract or converge the gases in a horizontal plane toward a central opening (42). The first partition (36) has a cup-shaped back surface so that contraction of the gases around the back side of the first partition (36) is highly effective in attenuating sound, and both partitions are sloped in a direction toward the outlet (28) from the muffler so as to minimize the generation of back pressure, which is not substantially greater than the back pressure in a straight pipe.
INTERNAL COMBUSTION ENGINE
by RAY T. FLUGGER
ABSTRACT
A compact, sound-attenuating muffler for a high-performance internal combustion engine is disclosed in which the muffler casing (21) has an elongated transverse cross-section with a height dimension of only slightly larger than the height dimension of the inlet exhaust pipe (22) and a width dimension in the range of about 2 to 4 1/2 times the height dimension, The muffler includes a divergently tapering planar first partition (36) which causes gases to be expanded only in a horizontal plane toward the side walls (38,39) of the muffler and further includes a second partition (41) formed to contract or converge the gases in a horizontal plane toward a central opening (42). The first partition (36) has a cup-shaped back surface so that contraction of the gases around the back side of the first partition (36) is highly effective in attenuating sound, and both partitions are sloped in a direction toward the outlet (28) from the muffler so as to minimize the generation of back pressure, which is not substantially greater than the back pressure in a straight pipe.
Description
~L;Z 455~ii6 -1 COMPACT, SOUND-ATTENUATING MUFFLER FOR HIGH-PEE~FO~I~ANCE, INTE~NAL COI~IBUSTION ENGINE
TECHNI~AL FI~D
Numerous muffler constructions have been proposed for the attenuation of the sound component of an exhaust yas stream from an internal combustion engine. Invariably, these structures have purported to effect sound attenuation without substantially or intolerably increasing the back pressure on the engine. As is well ~nown, muffler induced back pressure will substantially reduce internal combustion engine performance. The problem of reduced performanoe is mo~t extreme in high-performance racing engines. The "solution" to the problem which is actually used usually is merely to employ a straight pipe from the engine and tolerate the noise. With urban expansion, however, even race tracks are under pressure to reduce the noise level during racing~ Moreover, at least some high performance cars also are drivenl at least occasionally, on the city streets. In order to be "street-legal" such high per-formance engines must be coupled to a muffler, and the only mufflers which axe currently commercially available that are used on such high~performance engines cause a significant drop in engine power as a direct resul~ of the back pressure induced in the muffler.
~L~
Typically, a 575 horsepower engine will produce a noise level of about 130 db at hard acceleration with no muffler, and on the same engine when a commercially available high-performance muffler is usedJ the noise level will be reduced to about 95 db (A scale) at hard acceleration, but there also will be an 18 to q~
~245~6~
1 2~ power lo~s. Even larger engines~ for exa~lple 700 to 800 horsepower, have more cam overlap and cannot tolerate sound attenu~tion to 95 db since it would produce a 30 to 40% power 06s .
Another problem that complicates any atteTnpt to attenuate sound in high-performance internal combustion engines is the necessity to minimize bulk and weight. The exhaust pipe on a high horsepower engine typically will be about 4 inches in diameter so as to accommodate the very substantial volumetric flow. Mufflers which depend upon excessive length or diameter to achieve sound attenuation will be unsuitable for use on race cars, either because of their bulk or weight, or both.
The patent art contains various muffler constructions which purport to solve the problem of sound attenuation without undesirable back pressure, but in fact these various structures have substantial performance deficiencies. It is well known to provide a divergently tapered centrally located conical partition for flow of gases around the partition to effect an expansion of the gases. Typic~l of such structures are the devices shown in United States Patent Nos. 2,071,351, 2,239,549 and 2,971,599.
Some of these patented mufflers follow such an expansion partition or cone with a contraction or concentrating partition or baffle. Typical of such devices are the mufflers shown in United States Patent Nos. 1,081,348, 2,667,940, 3,029,895 and 3,029,896. These muf~lers, however~ do significantly increase back pressure by causing the exhaust gases to re~erse the direction of their flow axially as tbey attempt to pass beyond the concentrating or converging baffle. This flow reversal may be effective in sound attenuation, but it has been found to increase back pressure undesirably~
~Z~5~66 Even mufflers which employ ~lternating divergent and then convergent partitions have su:ffered from undesirable bulk and/or weight, inordinate complexity, or auxiliary flow channels or openings in the partitions which clefeat sound attenuation Typical of ~ucch mufflers are the mufflers set forth in United States Patent Nos. 624,062, 1,184,431, 2,325,905 and 2,485,555~
Additional patent art known to ap~licant but believed to he peripheral in relevance to the present invention are the following United States Patents: 1,677,57û, 1,756,916, ~0 l,g461908, 2,934,889, 3,219,141, 3,786,896, 4,1d~3,73g and ~46l783.
The reality of the industry is that high~performance racing cars are either using no mufler or mufflers which barely achieve ~he desired sound attenuation, and achieve it at a significant power loss and with an unidesirable increase in bulk and weightO
Accordingly, it is an object of the present invention to provide a compact, lightweight, sound-attenuating muffler for a high perormance internal combustion engine or the like which 29 achieves ~;ound attenuation without significant decrease in engine performance.
It ic~ another object of the present invention to provide a highly effective sound-attenuating muffler for a high-performance, internal combustion engine which is simple to construct, is compact, can be used on race cars or the like, is durable and is lightweight.
The compact, sound-attenuating muffle~ of the present invention has other objects and features of advantage which will become apparent from and are set forth in more detail in the 3~ following description of the preferred embodiment and the accompanying drawi.ng.
55~
1 ~ISCI~QSURF. OF INvENTIoN
The compact, sound-attenuat:ing muffler of the present invcntion includes a casing having an inlet opening formed for the 10w of exhaust gases into the casing and an outlet opening formed for the discharge oE gases from the casing. The muffler also includes partition means positioned in the casing and including a divergently tapered first partition formed to deflect gases toward side walls of the casing, and a convergently tapered second partition positioned downstream of the first partition and 1~ formed with a central opening therein for convergence of gases from the side walls to the opening. The improvement in the mufEler of the present invention comprises, briefly, a muffler in which a casing is formed with a transverse cross-section having a width dimension substantially greater than the height dimension, the first partition is formed to extend and to be imper-forate over the full height dimension of the casing and is formed to terminate short o~ the full width of the casing to define a pair of openir~gs proximate opposite side walls of the casing, and the second partition is formed to extend across both the width and
TECHNI~AL FI~D
Numerous muffler constructions have been proposed for the attenuation of the sound component of an exhaust yas stream from an internal combustion engine. Invariably, these structures have purported to effect sound attenuation without substantially or intolerably increasing the back pressure on the engine. As is well ~nown, muffler induced back pressure will substantially reduce internal combustion engine performance. The problem of reduced performanoe is mo~t extreme in high-performance racing engines. The "solution" to the problem which is actually used usually is merely to employ a straight pipe from the engine and tolerate the noise. With urban expansion, however, even race tracks are under pressure to reduce the noise level during racing~ Moreover, at least some high performance cars also are drivenl at least occasionally, on the city streets. In order to be "street-legal" such high per-formance engines must be coupled to a muffler, and the only mufflers which axe currently commercially available that are used on such high~performance engines cause a significant drop in engine power as a direct resul~ of the back pressure induced in the muffler.
~L~
Typically, a 575 horsepower engine will produce a noise level of about 130 db at hard acceleration with no muffler, and on the same engine when a commercially available high-performance muffler is usedJ the noise level will be reduced to about 95 db (A scale) at hard acceleration, but there also will be an 18 to q~
~245~6~
1 2~ power lo~s. Even larger engines~ for exa~lple 700 to 800 horsepower, have more cam overlap and cannot tolerate sound attenu~tion to 95 db since it would produce a 30 to 40% power 06s .
Another problem that complicates any atteTnpt to attenuate sound in high-performance internal combustion engines is the necessity to minimize bulk and weight. The exhaust pipe on a high horsepower engine typically will be about 4 inches in diameter so as to accommodate the very substantial volumetric flow. Mufflers which depend upon excessive length or diameter to achieve sound attenuation will be unsuitable for use on race cars, either because of their bulk or weight, or both.
The patent art contains various muffler constructions which purport to solve the problem of sound attenuation without undesirable back pressure, but in fact these various structures have substantial performance deficiencies. It is well known to provide a divergently tapered centrally located conical partition for flow of gases around the partition to effect an expansion of the gases. Typic~l of such structures are the devices shown in United States Patent Nos. 2,071,351, 2,239,549 and 2,971,599.
Some of these patented mufflers follow such an expansion partition or cone with a contraction or concentrating partition or baffle. Typical of such devices are the mufflers shown in United States Patent Nos. 1,081,348, 2,667,940, 3,029,895 and 3,029,896. These muf~lers, however~ do significantly increase back pressure by causing the exhaust gases to re~erse the direction of their flow axially as tbey attempt to pass beyond the concentrating or converging baffle. This flow reversal may be effective in sound attenuation, but it has been found to increase back pressure undesirably~
~Z~5~66 Even mufflers which employ ~lternating divergent and then convergent partitions have su:ffered from undesirable bulk and/or weight, inordinate complexity, or auxiliary flow channels or openings in the partitions which clefeat sound attenuation Typical of ~ucch mufflers are the mufflers set forth in United States Patent Nos. 624,062, 1,184,431, 2,325,905 and 2,485,555~
Additional patent art known to ap~licant but believed to he peripheral in relevance to the present invention are the following United States Patents: 1,677,57û, 1,756,916, ~0 l,g461908, 2,934,889, 3,219,141, 3,786,896, 4,1d~3,73g and ~46l783.
The reality of the industry is that high~performance racing cars are either using no mufler or mufflers which barely achieve ~he desired sound attenuation, and achieve it at a significant power loss and with an unidesirable increase in bulk and weightO
Accordingly, it is an object of the present invention to provide a compact, lightweight, sound-attenuating muffler for a high perormance internal combustion engine or the like which 29 achieves ~;ound attenuation without significant decrease in engine performance.
It ic~ another object of the present invention to provide a highly effective sound-attenuating muffler for a high-performance, internal combustion engine which is simple to construct, is compact, can be used on race cars or the like, is durable and is lightweight.
The compact, sound-attenuating muffle~ of the present invention has other objects and features of advantage which will become apparent from and are set forth in more detail in the 3~ following description of the preferred embodiment and the accompanying drawi.ng.
55~
1 ~ISCI~QSURF. OF INvENTIoN
The compact, sound-attenuat:ing muffler of the present invcntion includes a casing having an inlet opening formed for the 10w of exhaust gases into the casing and an outlet opening formed for the discharge oE gases from the casing. The muffler also includes partition means positioned in the casing and including a divergently tapered first partition formed to deflect gases toward side walls of the casing, and a convergently tapered second partition positioned downstream of the first partition and 1~ formed with a central opening therein for convergence of gases from the side walls to the opening. The improvement in the mufEler of the present invention comprises, briefly, a muffler in which a casing is formed with a transverse cross-section having a width dimension substantially greater than the height dimension, the first partition is formed to extend and to be imper-forate over the full height dimension of the casing and is formed to terminate short o~ the full width of the casing to define a pair of openir~gs proximate opposite side walls of the casing, and the second partition is formed to extend across both the width and
2~ height dimensions of the casing and being imperforate intermediate the casing walls except for the central opening. In the~preferred form, the height dimension of the casing is only slightly greater than the height dimension of the inlet opening to the casing, and the width dimension is at least about twice the height dimension for expansion and contraction of exhaust gases in substantially a single plane. In order to achieve attenuationt the divergent partition includes an extension section~ and in order to minimize back pressure the convergent partition pre~erably converges at a slope with respect to the side walls of the casing in the range of about 45 to about 70.
~L55~iq6 Y5~1~3L~QL THE DR~ING
~ IGURE 1 is a front elevational view of a rnufler constructed in accordance with the present invention.
FIGUP~E 2 is a top plan view, in cross-secti~n, taken substantially along the plane of line 2 2 in Fiyure 1.
FIGURE 3 is an enlarged, side-elevational view, in cross section, taken substantially along the plane of line 3-3 in Figure 1.
B~$'~ ~IQDE OF ~A~YING ~UT TEIE INVEN~LON
The muffler for high-performance, internal combustion engines of the present invention c~n be seen in the drawing to include a casing, generally designated 21/ an inlet pipe 22 extending through casing end wall members 23 and 24 ~or the flow of exhaust gases through inlet openin~ 25 into casing 21. The muffler further includes an outlet pipe 26 mounted to extend through casing end wall 27 and provide an outlet opening 28 for the discharge of gases from the casing. Mounted in casiny 21 is partition means, generally designated 29, which is formed for the attenuation of the sound component in the exhaust gases as the gases pass through the muffler, as will be described herei~after in more detail.
In order to facilitate fabrication of a high-strenyth, durable muffler, casing 21 is preferably formed from longitudi~
nally extending casing halves 31 and 32 which are joined together ~5 along longitudinally extending upper and lower seams 30, for example, by welding at 33. Casing end wall members 23, 24 and 27 are similarly welcled to the ends of casing halves 31 and 32, and the inlet and outlet exhaust pipes 22 and ~6 are in turn welded to the respective end walls of the casing. During the assembly ~z~
process, partitions means 29, each of which includes flanges 34, can be inserted into assembled casing halves and welded in place.
The construction of muffler casing 21 as above deseribed af~ords a structuLe which is very rigid and durable and accordingly capable of withstanding the substantial stresses inherent in high-perforrnance muffler operation.
As best may be seen in Figure 2, partition means 29 includes a ~irst partition 36 which is divergently tapered from the longitudinal ~enter line of the casing, which coincides with seam 30 between casing halves 31 and 32. First partition 36 defleets gases passing through inlet opening 25 from inlet exhaust pipe 22 outwardly toward the side walls 38 and 39 of casing 21. Mounted downstream of partition 36 is a seeond p~rtition 41 which is formed to be convergently tapered with respect to the central longitudinal axis of the muffler, Partition 41 is formed with central opening means 42 so that gases converging ~rom walls 38 and 39 pass through central opening 42, at which point they are discharged from the casing or, as shown in the drawing, impact an additional first partition 36a. In the mu~fler shown in the drawing, the divergence and eonvergenee of the exhaust stream is repeated when the exhaust gases are successfully deflected by an additional second partition 41a, still another first partitions 36b and finally an additional second partition 41b, which discharges the gases through opening 42b into outlet opening 28 and outlet exhaust pipe 26.
The suceessive outward deflection and then inward convergence of gases in a muffler is broadly known in the prior art, Sueh prior art structures, however, typically have partitions or baffle structures which induce undesirable baek i5~i~
1 pressur~, contain openings or passageways which diminish the sound attenuating ef~ectiveness of th~ muffler, or require excessive length, diameter and/or we:ight.
The muffler of the present invention achieves extremely effective ~ound attenuation without undesirable back pressure and S bulk or weight by iorming casing 21 with a transverse ClOSS
section having a width dimension substantially greater than the height dimension~ As used herein, the terlilAs "width" and "height"
refer to the muf~ler as oriented in Figure 1. It will be understood, however/ thak the muffler of the present invention can be installed and oriented at 90~ from the orien-tation shown in Figure 1, or at any desired angle with respect to inlet pipe 22~ Regardless of the orientation, however, the muffler casing or housing is forr~ed with an elongated transverse cross-section.
As best may be seen in Figures 1 and 3, the height din~ension o~ the casing is not substantially greater than the height dimension of inlet tube or pipe 22, while it is preferable that the width dimension of the casing be sufficient to such that the expansion ratio between the area of inlet pipe 22 and the cross-sectional area of the inside of the housing is in the range of about 1 to 3~ as a minimum, and 1 to B, as a maximum, This can be accomplished if the width dimension is at least about twice the height dimension of the casing but not more than about 4.5 times ~he height dimension. In the preferred ormg an expan~ion ratio between the area of inlet tube 22 and the internal transverse c~oss-section~l area of casing 21 is about 1 to 4, with the width dimension being about 2.4 times the height dimension~
In order to achieve the necessary expansion of gases, it is preferable that firs-~ partition 36 be formed as a solid ~2~5S~
1 imperforate mem~er which extends over the full height dimension of the ca~ing and yet does not extend over the full width dimension. Instead, partition 36 terminates short of the side ~asing walls 38 and 39 so as to define a pair of openings 46 and 47 proximate the opposite side walls of the casing. Addition-ally, instead of forming first partition 36 as a conicalpartitio~r as so custornarily is employed in the prior art, the first partition is provided by a pair of divergently tapering planar surfaces ~8 and 49 oriented in substantially vertical planes and connected at an apex positioned at substantially the center of the stream of exhaust gases discharged into the muffler through inlet pipe 22. This construction of first partition 36 produce~ expansion in substantially one plane, namely, the horizontal plane, as viewed in Pigure 1.
Second partition 41 is formed to extend across both the width and height dimensions of the casing and is fur~her formed to be imperforate intermediate the casing walls except for central opening means 42. Thus, all of the exhaust gases are forced to converge around the back side of cup-shaped first partition 36 toward central opening 4~ in the second partition.
There are no auxiliary pathways or openings in the second partition which will allow sound to pass directly along the casing walls. Again, instead of providing a conical or frusto-conical mem~er, second partition 41 is provided by a pair of convergently tapered planar surfaces 51 and 52 oriented in vertical planes and connected to a central planar surface 53 formed with opening 42 therein. Gases, therefore, converge in subs~antially a single plane, the horizontal plane.
In order to avoid undesirable back pressure in the muEfler while limiting the overall muffler length and accordingly ~2~5S;6 _g_ 1 bulk and weight, ~he converging planar surfaces 51 and 52 converge at a slope with respec-t to the side walls of the ca~ing in the range of about ~5 degLees to about 70 degrees~ Thus, angleC~ should not be yreater than 7~ degrees or else a substantial increase in back pressure is produced, and the angle also should not be less than 45 or else the overall length and weight of the muE~ler will be undesirably increased~ By way of illustration, the back pressure in the muffler is increased by 3 to 4 time~ when the angle ~ is increased from about 65 to about 10 ~~
Si~nilarly, in order to minimize back pressure and limit the overall muEfler lengthr it is preferable that planar surfaces 4B and 49 in first partition 36 diverge at an angle ~ which i5 equal to between abou-t ~5 and a~out 70.
In order to ~urther enhance soun~ and attenuation, the muffler of the present invention preferably includes a ~irst partition which is formed with extension means 56 at the edges thereof defining openings 46 and 47. The extension means extend~
along the longitudinal axis of the casing substantially parallel ~o the casing walls to define passayeways along the casing and a cup-shaped back side of the first partition. It has been found that the addition of extension means 56 to first partition 36 a~tenuates the sound by about 20 to 30~, as compared to a first partition without the extension means. Although increasing the length o~ the extension means does increase sound attenuation to some degree, it also increases the overall length of the muffler.
Even a short extension means produces a substantial sound attenuation over a first partition ~ormed without the extension.
Thus7 in a 12-inch (30.5 cm) wide muffler extension means 56 need only have a length of 1/2 to 3/4 inches ~1~3 to 1.9 centimeters).
55~6 1 ~PER~L~
As will be seen-from the drawing, thernuffler of ~he present invention includes three sets of first and second partitions. ~ach Aet o~ par~itions will attenua~e the sound component in the exhaust gases by about 1/2 to 2/3 of the sound level in the incominy gases. Three sets of partitions can be used to reduce the sound level on an 800 horsepower engine during maximum acceleration from about 130 db on the A scale (about 5,000 watts) to about ~0 db on the A scale (about one tenth of a wa~t). The back pressure generated by the muffler as shown in the drawings on an ~0 horsepower engine will produce less than 2~ power loss, with the back pressure being in the range of 1/2 to 1 psi, as compared to commercially available high-performance mufflers which typically will produce a back pressure of between lS and 20 psi and a 15 to 20~ power loss.
~L55~iq6 Y5~1~3L~QL THE DR~ING
~ IGURE 1 is a front elevational view of a rnufler constructed in accordance with the present invention.
FIGUP~E 2 is a top plan view, in cross-secti~n, taken substantially along the plane of line 2 2 in Fiyure 1.
FIGURE 3 is an enlarged, side-elevational view, in cross section, taken substantially along the plane of line 3-3 in Figure 1.
B~$'~ ~IQDE OF ~A~YING ~UT TEIE INVEN~LON
The muffler for high-performance, internal combustion engines of the present invention c~n be seen in the drawing to include a casing, generally designated 21/ an inlet pipe 22 extending through casing end wall members 23 and 24 ~or the flow of exhaust gases through inlet openin~ 25 into casing 21. The muffler further includes an outlet pipe 26 mounted to extend through casing end wall 27 and provide an outlet opening 28 for the discharge of gases from the casing. Mounted in casiny 21 is partition means, generally designated 29, which is formed for the attenuation of the sound component in the exhaust gases as the gases pass through the muffler, as will be described herei~after in more detail.
In order to facilitate fabrication of a high-strenyth, durable muffler, casing 21 is preferably formed from longitudi~
nally extending casing halves 31 and 32 which are joined together ~5 along longitudinally extending upper and lower seams 30, for example, by welding at 33. Casing end wall members 23, 24 and 27 are similarly welcled to the ends of casing halves 31 and 32, and the inlet and outlet exhaust pipes 22 and ~6 are in turn welded to the respective end walls of the casing. During the assembly ~z~
process, partitions means 29, each of which includes flanges 34, can be inserted into assembled casing halves and welded in place.
The construction of muffler casing 21 as above deseribed af~ords a structuLe which is very rigid and durable and accordingly capable of withstanding the substantial stresses inherent in high-perforrnance muffler operation.
As best may be seen in Figure 2, partition means 29 includes a ~irst partition 36 which is divergently tapered from the longitudinal ~enter line of the casing, which coincides with seam 30 between casing halves 31 and 32. First partition 36 defleets gases passing through inlet opening 25 from inlet exhaust pipe 22 outwardly toward the side walls 38 and 39 of casing 21. Mounted downstream of partition 36 is a seeond p~rtition 41 which is formed to be convergently tapered with respect to the central longitudinal axis of the muffler, Partition 41 is formed with central opening means 42 so that gases converging ~rom walls 38 and 39 pass through central opening 42, at which point they are discharged from the casing or, as shown in the drawing, impact an additional first partition 36a. In the mu~fler shown in the drawing, the divergence and eonvergenee of the exhaust stream is repeated when the exhaust gases are successfully deflected by an additional second partition 41a, still another first partitions 36b and finally an additional second partition 41b, which discharges the gases through opening 42b into outlet opening 28 and outlet exhaust pipe 26.
The suceessive outward deflection and then inward convergence of gases in a muffler is broadly known in the prior art, Sueh prior art structures, however, typically have partitions or baffle structures which induce undesirable baek i5~i~
1 pressur~, contain openings or passageways which diminish the sound attenuating ef~ectiveness of th~ muffler, or require excessive length, diameter and/or we:ight.
The muffler of the present invention achieves extremely effective ~ound attenuation without undesirable back pressure and S bulk or weight by iorming casing 21 with a transverse ClOSS
section having a width dimension substantially greater than the height dimension~ As used herein, the terlilAs "width" and "height"
refer to the muf~ler as oriented in Figure 1. It will be understood, however/ thak the muffler of the present invention can be installed and oriented at 90~ from the orien-tation shown in Figure 1, or at any desired angle with respect to inlet pipe 22~ Regardless of the orientation, however, the muffler casing or housing is forr~ed with an elongated transverse cross-section.
As best may be seen in Figures 1 and 3, the height din~ension o~ the casing is not substantially greater than the height dimension of inlet tube or pipe 22, while it is preferable that the width dimension of the casing be sufficient to such that the expansion ratio between the area of inlet pipe 22 and the cross-sectional area of the inside of the housing is in the range of about 1 to 3~ as a minimum, and 1 to B, as a maximum, This can be accomplished if the width dimension is at least about twice the height dimension of the casing but not more than about 4.5 times ~he height dimension. In the preferred ormg an expan~ion ratio between the area of inlet tube 22 and the internal transverse c~oss-section~l area of casing 21 is about 1 to 4, with the width dimension being about 2.4 times the height dimension~
In order to achieve the necessary expansion of gases, it is preferable that firs-~ partition 36 be formed as a solid ~2~5S~
1 imperforate mem~er which extends over the full height dimension of the ca~ing and yet does not extend over the full width dimension. Instead, partition 36 terminates short of the side ~asing walls 38 and 39 so as to define a pair of openings 46 and 47 proximate the opposite side walls of the casing. Addition-ally, instead of forming first partition 36 as a conicalpartitio~r as so custornarily is employed in the prior art, the first partition is provided by a pair of divergently tapering planar surfaces ~8 and 49 oriented in substantially vertical planes and connected at an apex positioned at substantially the center of the stream of exhaust gases discharged into the muffler through inlet pipe 22. This construction of first partition 36 produce~ expansion in substantially one plane, namely, the horizontal plane, as viewed in Pigure 1.
Second partition 41 is formed to extend across both the width and height dimensions of the casing and is fur~her formed to be imperforate intermediate the casing walls except for central opening means 42. Thus, all of the exhaust gases are forced to converge around the back side of cup-shaped first partition 36 toward central opening 4~ in the second partition.
There are no auxiliary pathways or openings in the second partition which will allow sound to pass directly along the casing walls. Again, instead of providing a conical or frusto-conical mem~er, second partition 41 is provided by a pair of convergently tapered planar surfaces 51 and 52 oriented in vertical planes and connected to a central planar surface 53 formed with opening 42 therein. Gases, therefore, converge in subs~antially a single plane, the horizontal plane.
In order to avoid undesirable back pressure in the muEfler while limiting the overall muffler length and accordingly ~2~5S;6 _g_ 1 bulk and weight, ~he converging planar surfaces 51 and 52 converge at a slope with respec-t to the side walls of the ca~ing in the range of about ~5 degLees to about 70 degrees~ Thus, angleC~ should not be yreater than 7~ degrees or else a substantial increase in back pressure is produced, and the angle also should not be less than 45 or else the overall length and weight of the muE~ler will be undesirably increased~ By way of illustration, the back pressure in the muffler is increased by 3 to 4 time~ when the angle ~ is increased from about 65 to about 10 ~~
Si~nilarly, in order to minimize back pressure and limit the overall muEfler lengthr it is preferable that planar surfaces 4B and 49 in first partition 36 diverge at an angle ~ which i5 equal to between abou-t ~5 and a~out 70.
In order to ~urther enhance soun~ and attenuation, the muffler of the present invention preferably includes a ~irst partition which is formed with extension means 56 at the edges thereof defining openings 46 and 47. The extension means extend~
along the longitudinal axis of the casing substantially parallel ~o the casing walls to define passayeways along the casing and a cup-shaped back side of the first partition. It has been found that the addition of extension means 56 to first partition 36 a~tenuates the sound by about 20 to 30~, as compared to a first partition without the extension means. Although increasing the length o~ the extension means does increase sound attenuation to some degree, it also increases the overall length of the muffler.
Even a short extension means produces a substantial sound attenuation over a first partition ~ormed without the extension.
Thus7 in a 12-inch (30.5 cm) wide muffler extension means 56 need only have a length of 1/2 to 3/4 inches ~1~3 to 1.9 centimeters).
55~6 1 ~PER~L~
As will be seen-from the drawing, thernuffler of ~he present invention includes three sets of first and second partitions. ~ach Aet o~ par~itions will attenua~e the sound component in the exhaust gases by about 1/2 to 2/3 of the sound level in the incominy gases. Three sets of partitions can be used to reduce the sound level on an 800 horsepower engine during maximum acceleration from about 130 db on the A scale (about 5,000 watts) to about ~0 db on the A scale (about one tenth of a wa~t). The back pressure generated by the muffler as shown in the drawings on an ~0 horsepower engine will produce less than 2~ power loss, with the back pressure being in the range of 1/2 to 1 psi, as compared to commercially available high-performance mufflers which typically will produce a back pressure of between lS and 20 psi and a 15 to 20~ power loss.
Claims (4)
1. A compact, sound-attenuating muffler for a high-performance, internal combustion engine or the like including a casing having an inlet opening formed for the flow of exhaust gases into said casing, an outlet opening formed for the discharge of gases from said casing, and partition means positioned in said casing and including a divergently tapered imperforate first partition extending over the full height dimension of said casing and terminating short of the full width dimension of said casing to define a pair of openings proximate opposite side walls of said casing, said first partition deflecting gases toward side walls of said casing, and a convergently tapered second partition positioned downstream of said first partition and formed with central opening means in otherwise imperforate walls for convergence of gases from said side walls to said opening, characterized by:
said casing having substantially the same cross-sectional area over the length of said casing to limit expansion of said exhaust gases in said casing after entry of said gases through said inlet opening into said casing in order to reduce eddy current and minimize the backpressure generated in said muffler.
said casing having substantially the same cross-sectional area over the length of said casing to limit expansion of said exhaust gases in said casing after entry of said gases through said inlet opening into said casing in order to reduce eddy current and minimize the backpressure generated in said muffler.
2. The compact, sound-attenuating muffler as defined in Claim 1, wherein, said first partition is formed with extension means at edges thereof defining said openings, said extension means extending along the longitudinal axis of said casing substantially parallel to said walls to define passageways along said casing and a cup-shaped configuration on the back side of said first partition in front of said second partition.
3. The compact, sound-attenuating muffler as defined in Claim 1, wherein, said casing has a constant height dimension over the length of said casing not substantially greater than the height dimension of said inlet opening and a constant width dimension over the length of said casing in the range of about 2.0 to 4.5 times the height dimension.
4. The compact, sound-attenuating muffler as defined in Claim 1, wherein, said casing has a constant height dimension over the length of said casing slightly larger than the height dimension of said inlet pipe and a constant width dimension over the length of said casing producing an expansion ratio between the area of said pipe and the constant internal area of said casing in the range of not less than about 1 to 3 and not greater than about 1 to 6.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CA000487580A CA1245566A (en) | 1985-07-26 | 1985-07-26 | Compact, sound-attenuating muffler for high- performance, internal combustion engine |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CA000487580A CA1245566A (en) | 1985-07-26 | 1985-07-26 | Compact, sound-attenuating muffler for high- performance, internal combustion engine |
Publications (1)
Publication Number | Publication Date |
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CA1245566A true CA1245566A (en) | 1988-11-29 |
Family
ID=4131063
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
CA000487580A Expired CA1245566A (en) | 1985-07-26 | 1985-07-26 | Compact, sound-attenuating muffler for high- performance, internal combustion engine |
Country Status (1)
Country | Link |
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CA (1) | CA1245566A (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN109899131A (en) * | 2019-04-24 | 2019-06-18 | 济南吉美乐电源技术有限公司 | A kind of high reliable plate-type silencer |
-
1985
- 1985-07-26 CA CA000487580A patent/CA1245566A/en not_active Expired
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN109899131A (en) * | 2019-04-24 | 2019-06-18 | 济南吉美乐电源技术有限公司 | A kind of high reliable plate-type silencer |
CN109899131B (en) * | 2019-04-24 | 2023-11-03 | 济南吉美乐电源技术有限公司 | High-reliability plate-type muffler |
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