US3786897A - Exhaust muffler for two-stroke cycle engine - Google Patents

Exhaust muffler for two-stroke cycle engine Download PDF

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Publication number
US3786897A
US3786897A US00243349A US3786897DA US3786897A US 3786897 A US3786897 A US 3786897A US 00243349 A US00243349 A US 00243349A US 3786897D A US3786897D A US 3786897DA US 3786897 A US3786897 A US 3786897A
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United States
Prior art keywords
chamber
tube
opening
housing
exhaust
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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US00243349A
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English (en)
Inventor
I Swanson
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Donaldson Co Inc
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Donaldson Co Inc
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Publication date
Application filed by Donaldson Co Inc filed Critical Donaldson Co Inc
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N1/00—Silencing apparatus characterised by method of silencing
    • F01N1/02—Silencing apparatus characterised by method of silencing by using resonance
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B25/00—Engines characterised by using fresh charge for scavenging cylinders
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2490/00—Structure, disposition or shape of gas-chambers
    • F01N2490/15—Plurality of resonance or dead chambers
    • F01N2490/155—Plurality of resonance or dead chambers being disposed one after the other in flow direction
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B75/00—Other engines
    • F02B75/02—Engines characterised by their cycles, e.g. six-stroke
    • F02B2075/022—Engines characterised by their cycles, e.g. six-stroke having less than six strokes per cycle
    • F02B2075/025—Engines characterised by their cycles, e.g. six-stroke having less than six strokes per cycle two
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B2700/00—Measures relating to the combustion process without indication of the kind of fuel or with more than one fuel
    • F02B2700/03—Two stroke engines
    • F02B2700/031—Two stroke engines with measures for removing exhaust gases from the cylinder
    • F02B2700/032—Two stroke engines with measures for removing exhaust gases from the cylinder by means of the exhaust gases

Definitions

  • ABSTRACT A muffler housing with an axial inlet is shown.
  • a tube 52 1 U S Isl/54 3?) g g extends axially Into the housing from the Inlet.
  • a [51] Int Cl 6 U08 closed tuning chamber is provided in the housing sur- [58] Fie'ld /312 314 rounding the tube adjacent the inlet end.
  • the tube has l81/41 33 D 36 a single opening leading to the tuning chamber.
  • a louver is mounted on the tube in the chamber to extend [56] References Cited over the opening. The louver acts as a megaphone portion to enhance performance of the two cycle en- UNITED STATES PATENTS gine.
  • the housing is provided with baffles and cham- 3,209,858 10/1965 Jettinghoff 181/54 berg downstream from the tuning chamber to muffle exhaust noises and further enhance performance of on oeve 3,434,280 3/1969 Burkhart 60/314 the engme. 3,434,565 3/1969 Fischer 181/54 X 8 Claims, 3 Drawing Figures sli Q00 O 2600 00000 OC25 Z5 EXIIAUST MUFFLER FOR TWO-STROKE CYCLE ENGINE BACKGROUND OF THE INVENTION 1.
  • This invention relates generally to the field of exhaust mufflers, and more particularly relates to an exhaust muffler for two-stroke cycle engines, which incorporates a megaphone-like device to enhance engine performance.
  • a properly designed exhaust device or system can increase the horsepower of a two cycle engine up to 35 percent over the output of the basic engine without a muffler system. The increase in performance is greater when compared with an engine having a poorly designed exhaust system.
  • One known method of improving two cycle engine performance is to utilize an exhaust device called a megaphone.
  • the megaphone is an exhaust pipe having a diverging end such that a negative pressure wave is supplied to the open exhaust port at the proper time to improve scavenging.
  • the length of the megaphone, and its crosssectional dimensions, are designed such that maximum negative pressure is supplied to the exhaust port at bottom dead center of crank shaft rotation.
  • the megaphone generates noise in the sense that the noise emanating from a megaphone is greater than the noise emanating from a nondivergent tube of the same diameter as the small end of the megaphone. Therefore, in prior art systems, the megaphone placed an abnormal silencing load on the mufflers silencing element.
  • the next step was my recognition that placing the tuning chamber for the megaphone outside of the gas flow path would reduce noise generation.
  • the tuning chamber is placed outside of the gas flow path and is in communication therewith by means of a single opening in the exhaust pipe, which passes through the tuning chamber.
  • a louver is mounted over the hole in the tuning chamber to simulate a megaphone portion.
  • the exhaust pipe extends through the tuning chamber into a downstream muffler. The results of this combination have been highly gratifying.
  • the tuning chamber and louver act as a megaphone to enhance engine performance.
  • any additional noise generated in the tuning chamber is reflected back toward the engine but is prevented by the louver from being reflected downstream toward the muffler.
  • I was able to achieve satisfactory sound reduction with less than normal restriction to gas flow.
  • a second closed tuning chamber at the end of the main exhaust tube substantially improves torque at low engine speeds.
  • the chamber at the end of the main tube reflects a suitable pressure wave at low engine speeds. Because the overall system length at the end of the main tube is longer than the primary tuned length, a modified pressure wave is formed which enhances low speed torque. This improves overall performance because typically, a megaphone is less effective at low engine speeds.
  • FIG. 1 is a view in side elevation of an exhaust muffler according to my invention, portions thereof being broken away and portions being shown in section;
  • FIG. 2 is a view, primarily in section, taken along line 22 of FIG. I;
  • FIG. 3 is a view in section taken along line 33 of FIG. 1.
  • FIG. I an exhaust muffler for a two-stroke cycle engine.
  • the muffler has a generally cylindrical housing 10, the opposite ends of which are provided with end caps 11 and I2.
  • End cap 12 is provided with an axial inlet opening defined by an outwardly extending flange 12a.
  • Mounted along the axis of housing I0 is an exhaust inlet tube 13 having one end thereof extending from the opening in end cap 12 and the other end thereof terminating within housing 10 about threefourths of the distance from end cap 12 to end cap II.
  • inlet tube 13 has a circular cross section throughout its entire length.
  • the outer wall'of the inlet end of tube I3 is sealed to flange 12a by welding or the like to prevent gas flow therebetween.
  • housing I0 The interior of housing I0 is divided into compartments or chambers including a closed tuning chamber 15, a resonator chamber 16, a second closed tuning chamber 17 and an exhaust gas collector compartment 18, by means of three baffle plates 19, 20 and 21.
  • the interior of housing I0 is divided into compartments or chambers including a closed tuning chamber 15, a resonator chamber 16, a second closed tuning chamber 17 and an exhaust gas collector compartment 18, by means of three baffle plates 19, 20 and 21.
  • baffle plates l9-21 are generally circular discs each having an outer peripheral flange engaging the inner wall of housing 10 around the circumference thereof. The discs may be welded or otherwise attached to the inner wall surface of the housing 10 to prevent gas flow therebetween.
  • Baffle plates 19 and 21) are each provided with a flanged central opening through which the exhaust inlet tube 13 extends. Again, the flanged open ings of baffle plates 19 and 20 securely engage tube 13 to prevent gas flow therebetween.
  • Compartment is a first tuning chamber located adjacent the inlet end of the muffler housing, between baffle plate 19 and end cap 12.
  • tuning chamber 15 is a toroidal chamber surrounding inlet tube 13.
  • a single axially and circumferentially extending opening 23 is formed in the wall of inlet tube 13 to provide communication of tube 13 with chamber 15.
  • the single opening 23 is preferably formed approximately mid-way between the ends of tuning chamber 15 and is sized so that the area of the opening or hole 23 is approximately 70 percent of the cross-sectional area of the tube 13. In the units l have tested, this size of opening appears to give the best results. However, an opening of almost any reasonable size will give some improved results.
  • a metal louver 24 is mounted on the tube 13 in tuning chamber 15 to shield the opening 23.
  • the louver is secured by a flange 24a adjacent the upstream edge of the opening 23 around approximately three-fourths of the periphery thereof and diverges in a downstream direction over at least part of the opening, the unattached side of the louver 24 being the downstream side thereof.
  • the louver 24 is long enough to cover the entire opening 23, and so that the downstream edge of the louver 24 lies in a plane perpendicular to the axis of tube 13. As viewed from the downstream end of the tuning chamber 15, looking toward end cap 12, and as shown in FIG. 3, a generally oval opening is defined by the downstream end of the louver 24.
  • louver 24 would act like a portion of a megaphone. A portion of the sound waves emanating from the engine would enter tuning chamber 15 as indicated by the arrows in FIG. 1. The chamber 15 would resonate at a particular frequency and would reflect negative pressure waves back toward the engine to enhance scavenging. The louver 24!, however, would act as a baffle to substantially prevent reflection of sound waves through opening 23 downstream toward end cap 11. Therefore, tuning chamber 15 does not act as a noise generator to increase the noise load on the downstream muffler components.
  • the next downstream chamber 16 is formed between the baffle plates 19 and 20.
  • the chamber 16 and perforations 25 act as a helmholtz resonator to provide noise cancellation within a particular frequency range.
  • Compartment 16 is in fluid communication with the last compartment 18 by means of a plurality of pipes 26.
  • Each pipe 26 is spaced approximately mid-way between the outer surface of tube 13 and the inner wall surface of housing 10.
  • the pipes 26 extend through suitable openings formed in baffle plates 20 and 21, the openings being sized to prevent gas flow between the baffle plates and tubes. Therefore, the exhaust gases in compartment 16 can freely pass through pipes 26 for discharge in compartment 18.
  • Compartment 18, which is located between baffle plate 21 and end cap ll, is provided with a radially extending outlet tube 27 from which the exhaust gases leave the housing 10.
  • compartment 17 is located between baffle plates 20 and 21.
  • the downstream end of inlet tube 13 terminates at approximately the center of compartment 17.
  • Compartment 17 therefore acts as an expansion and contraction chamber to provide additional sound attenuation.
  • this compartment or chamber 17, which surrounds the open outlet end of the exhaust tube 13 acts to enhance performance, especially at low engine speeds.
  • louver means mounted on said tube in said tuning chamber adjacent an upstream side of said opening and diverging away from said opening into said chamber in a downstream direction to shield said single opening to substantially prevent pressure waves from leaving said tuning chamber in a downstream direction while directing energy developed in the tuning chamber toward said engine to enhance the performance thereof;
  • said housing containing silencing means downstream from said tuning chamber.
  • a louver mounted on said tube in said tuning chamber to shield said single opening to substantially prevent pressure waves from leaving said tuning chamber in a downstream direction while directing energy developed in the tuning chamber toward said engine to enhance the performance thereof;
  • said housing containing silencing means downstream from said tuning chamber;
  • means including openings in said tube wall between the ends thereof to provide an exhaust gas flow path to said outlet opening of said housing.
  • the muffler of claim 3 including an exhaust gas collector compartment in said other end of said housing opposite said second tuning chamber from said resonator chamber, said outlet opening leading from said compartment, and a plurality of pipes leading from said resonator chamber to said compartment to permit exhaust gas flow therebetween.
  • An exhaust unit for two-stroke cycle engines comprising:
  • a megaphone portion mounted on the upstream edge of said opening on said tube in said chamber, said megaphone portion diverging from said opening into said chamber in a downstream direction over at least part of said opening to substantially prevent reflected sound waves from leaving said chamber in a direction away from the engine while directing sound wave energy developed in said chamber toward the engine to enhance the performance thereof.
  • Exhaust apparatus for two-stroke cycle engines comprising:
  • an exhaust tube having an inlet end adapted to be connected to the exhaust discharge port of an engine, an exhaust outlet end, and an axially extending opening in a side wall thereof between said ends;
  • louver means mounted on the upstream side of said opening on said tube in said chamber adjacent said opening, said louver diverging away from said opening in a downstream direction over at least part of said opening to act with said chamber as a megaphone to enhance engine performance.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Exhaust Silencers (AREA)
  • Soundproofing, Sound Blocking, And Sound Damping (AREA)
US00243349A 1972-04-12 1972-04-12 Exhaust muffler for two-stroke cycle engine Expired - Lifetime US3786897A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US24334972A 1972-04-12 1972-04-12

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Country Status (4)

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US (1) US3786897A (ja)
JP (1) JPS4914841A (ja)
CA (1) CA975228A (ja)
DE (2) DE2309571A1 (ja)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3853201A (en) * 1972-05-31 1974-12-10 Outboard Marine Corp Quiet snowmobile
US4046219A (en) * 1975-03-20 1977-09-06 Brunswick Corporation Exhaust silencer apparatus for internal combustion engine
US4220219A (en) * 1978-09-14 1980-09-02 Flugger Ray T Lightweight muffler and method for muffling noise
US6082487A (en) * 1998-02-13 2000-07-04 Donaldson Company, Inc. Mufflers for use with engine retarders; and methods
US6148519A (en) * 1998-09-18 2000-11-21 Donaldson Company, Inc. Apparatus for installing a packing material in a muffler assembly; and methods thereof
US6354398B1 (en) 1998-02-13 2002-03-12 Donaldson Company, Inc. Mufflers for use with engine retarders; and methods
US6571910B2 (en) 2000-12-20 2003-06-03 Quiet Storm, Llc Method and apparatus for improved noise attenuation in a dissipative internal combustion engine exhaust muffler
US20090236174A1 (en) * 2006-10-03 2009-09-24 Toyota Jidosha Kabushiki Kaisha Exhaust apparatus of vehicle engine
US20140076648A1 (en) * 2008-10-10 2014-03-20 Polaris Industries Inc. Snowmobile

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101283242B1 (ko) * 2010-10-08 2013-07-11 현대자동차주식회사 차량용 소음기

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1021641B (de) * 1953-10-24 1957-12-27 Tydens Patenter Ab Zweiflutige Schalldaempferanordnung
US3009530A (en) * 1960-01-21 1961-11-21 Laco Oil Burner Co Inc Exhaust device
US3209858A (en) * 1963-06-25 1965-10-05 Walker Mfg Co Muffler having depressed channel forming tuning passages
US3375898A (en) * 1966-07-15 1968-04-02 Hanlon & Wilson Co Muffler with perforate chordal baffles defining fiber-filled chambers
US3434280A (en) * 1967-11-20 1969-03-25 Joe H Burkhart Exhaust chamber
US3434565A (en) * 1967-12-21 1969-03-25 Walker Mfg Co Silencer with angled tuning tube leading to helmholtz resonator
US3462947A (en) * 1968-11-15 1969-08-26 Klaus Frederick Nowak Exhaust system for two-stroke engines

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1021641B (de) * 1953-10-24 1957-12-27 Tydens Patenter Ab Zweiflutige Schalldaempferanordnung
US3009530A (en) * 1960-01-21 1961-11-21 Laco Oil Burner Co Inc Exhaust device
US3209858A (en) * 1963-06-25 1965-10-05 Walker Mfg Co Muffler having depressed channel forming tuning passages
US3375898A (en) * 1966-07-15 1968-04-02 Hanlon & Wilson Co Muffler with perforate chordal baffles defining fiber-filled chambers
US3434280A (en) * 1967-11-20 1969-03-25 Joe H Burkhart Exhaust chamber
US3434565A (en) * 1967-12-21 1969-03-25 Walker Mfg Co Silencer with angled tuning tube leading to helmholtz resonator
US3462947A (en) * 1968-11-15 1969-08-26 Klaus Frederick Nowak Exhaust system for two-stroke engines

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3853201A (en) * 1972-05-31 1974-12-10 Outboard Marine Corp Quiet snowmobile
US4046219A (en) * 1975-03-20 1977-09-06 Brunswick Corporation Exhaust silencer apparatus for internal combustion engine
US4220219A (en) * 1978-09-14 1980-09-02 Flugger Ray T Lightweight muffler and method for muffling noise
US6082487A (en) * 1998-02-13 2000-07-04 Donaldson Company, Inc. Mufflers for use with engine retarders; and methods
US6354398B1 (en) 1998-02-13 2002-03-12 Donaldson Company, Inc. Mufflers for use with engine retarders; and methods
US6148519A (en) * 1998-09-18 2000-11-21 Donaldson Company, Inc. Apparatus for installing a packing material in a muffler assembly; and methods thereof
US6571910B2 (en) 2000-12-20 2003-06-03 Quiet Storm, Llc Method and apparatus for improved noise attenuation in a dissipative internal combustion engine exhaust muffler
US20090236174A1 (en) * 2006-10-03 2009-09-24 Toyota Jidosha Kabushiki Kaisha Exhaust apparatus of vehicle engine
US20140076648A1 (en) * 2008-10-10 2014-03-20 Polaris Industries Inc. Snowmobile
US9809195B2 (en) * 2008-10-10 2017-11-07 Polaris Industries Inc. Snowmobile
US11772601B2 (en) 2008-10-10 2023-10-03 Polaris Industries Inc. Vehicle security system

Also Published As

Publication number Publication date
CA975228A (en) 1975-09-30
DE2309571A1 (de) 1973-10-18
DE7307335U (de) 1976-09-30
JPS4914841A (ja) 1974-02-08

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