EP0020823A1 - Abgasschalldämpfer für einen Motor - Google Patents

Abgasschalldämpfer für einen Motor Download PDF

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Publication number
EP0020823A1
EP0020823A1 EP79301033A EP79301033A EP0020823A1 EP 0020823 A1 EP0020823 A1 EP 0020823A1 EP 79301033 A EP79301033 A EP 79301033A EP 79301033 A EP79301033 A EP 79301033A EP 0020823 A1 EP0020823 A1 EP 0020823A1
Authority
EP
European Patent Office
Prior art keywords
annular passage
silencer
wall
exhaust tube
chamber
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.)
Withdrawn
Application number
EP79301033A
Other languages
English (en)
French (fr)
Inventor
Lionel Fothergill
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.)
Individual
Original Assignee
Individual
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Priority claimed from IE36679A external-priority patent/IE790366L/xx
Application filed by Individual filed Critical Individual
Priority to EP79301033A priority Critical patent/EP0020823A1/de
Publication of EP0020823A1 publication Critical patent/EP0020823A1/de
Withdrawn legal-status Critical Current

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Classifications

    • 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
    • F01N1/08—Silencing apparatus characterised by method of silencing by reducing exhaust energy by throttling or whirling
    • F01N1/085—Silencing apparatus characterised by method of silencing by reducing exhaust energy by throttling or whirling using a central core throttling gas passage
    • 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
    • F01N1/08—Silencing apparatus characterised by method of silencing by reducing exhaust energy by throttling or whirling
    • F01N1/10—Silencing apparatus characterised by method of silencing by reducing exhaust energy by throttling or whirling in combination with sound-absorbing materials
    • 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
    • F01N1/24—Silencing apparatus characterised by method of silencing by using sound-absorbing materials

Definitions

  • the invention relates to apparatus for attenuating the poise caused by a moving stream -of gases.
  • engine exhaust silencer Such apparatus is most commonly embodied in the form of an engine exhaust silencer, and will be referred to as such throughout the rest of this specification. It is to be understood, however, that the term “engine exhaust silencer” is used for convenience only and is not to be used to limit the scope of the invention unduly.
  • annular passage type of silencer absorbs relatively little of the power of the engine, whereas the perforated exhaust type of silencer tends to absorb relatively more of the engine power; but the latter type of silencer tends to provide much greater sound attenuation when used on vehicles (in which the overall length of the silencer is necessarily limited).
  • a primary object of the invention is to provide an improved exhaust silencer which, when installed for example in the exhaust outlet of an internal combustion engine, will provide substantial reduction of exhaust gas noise without unduly affecting the engine performance.
  • the invention provides an engine exhaust silencer in which the gases are first led along an elongate annular passage defined between two chambers mounted one within another, and are then funnelled into and along an elongate exhaust tube whose longitudinal wall is perforated and is surrounded by one or more noise attenuating chambers, the outer wall of the annular passage converging towards but ending just short of the exhaust tube, and the gap between the two being surrounded by and opening into an expansion chamber.which joins.and seals the annular passage exit to the exhaust tube inlet.
  • the size of the gap, the area of the expansion chamber, and the rate of convergence of the annular passage-exit, will of course be balanced against one another in order to achieve a practical embodiment. For example, if the gap were to be made unsuitably large, the "venturi" effect would be lost; whereas if the gap were to be abnormally small, the back pressure at the silencer exhaust would rise unacceptably.
  • the inner chamber defining the annular passage or the sound attenuating chamber or chambers surrounding the exhaust tube, is filled with sound absorbing material such as steel wool or fibre glass, the noise attenuation will be further improved.
  • sound absorbing material such as steel wool or fibre glass
  • This art is already known in itself.
  • the inner chamber defining the annular passage contains sound absorbing material and has a down stream wall which is perforated to allow the gas flowing over the chamber to communicate with said sound absorbing material, the efficiency is improved still farther.
  • the perforated end wall in conjunction with the converging outer wall of the annular passage creates gas flow conditions which materially increase. the attenuation properties of the silencer.
  • the downstream end of the inner chamber defining the annular passage is streamlined, irrespective of whether or not it is also perforated, further benefits are obtained.
  • the streamlined end of the inner chamber could continue approximately parallel with the converging annular passage outer wall, and could be unperforated. It would then assist the gas flow towards the exhaust tube, as well as improving the sound attenuation by effectively prolonging the annular pas.sage.
  • the downstream end of the inner chamber could be streamlined and could be perforated as well. The chamber could then either be filled with sound absorbing material, or could be without such material and could constitute a sound attenuating resonating chamber.
  • downstream end of the inner chamber could taper towards the exhaust tube inlet but could be in the form of an open ended cone, with the inner chamber being closed off inside that cone by a separate perforated end wall.
  • This construction is especially advantagous since it provides an expansion area within the walls of the open ended tapering cone, thus lowering the back pressure at the eventual exhaust.
  • the noise attenuating properties of a silencer embodying the invention can be further increased, if the expansion chamber joins and seals the annular passage exit to the exhaust tube through the intermediary of a further tube, the further tube also having, part way along its length, an annular gap which is surrounded by and opens into a sealed expansion chamber.
  • the gases leave the annular passage exit and are funnelled into the further tube from whence they pass straight into the exhaust tube.
  • the presence of the annular gap and the expansion chamber of the intermediate tube tends to remove very deep resonant notes. This construction is thus especially useful on silencers which are intended for fitment to large diesel engines.
  • the cross-sectional area of the annular passage is never less than the cross-sectional area of the silencer inlet. This again avoids build up of back pressure.
  • the front end wall 14 of the inner chamber, onto which the incoming gases impinge, is generally convex.
  • the downstream end wall 15 of the chamber is perforated, as indicated in broken line in Figure 1, and the chamber is tightly packed with sound absorbing material such as steel wool or fibre glass.
  • the longitudinal wall of the cylindrical chamber 13 is not perforated.
  • the outer chamber 12 narrows at its downstream end. This narrowing is achieved by welding an open ended cone frustum 16 inside the chamber so that the cone frustum 16 effectively constitutes an extension of the outer chamber 12.
  • the gases from the annular passage are thus forced to follow the taper of the cone frustum 16, and in the area of this frustum shaped channel 16 considerable noise attenuation is achieved by gas and pressure waves passing through the perforations in the wall 15 of the inner chamber 13 and contacting the sound absorbing material within that chamber.
  • the cone frustum 16 converges towards, but stops just short of, the inlet of an exhaust tube 17 which constitutes the second portion of the silencer.
  • the longitudinal cylindrical wall of the tube 17 is perforated.
  • Respective end walls 18a, 18b seal the radial gap between the tube 17 and the outer chamber 12 of the silencer, and the annular chamber so defined is again tightly packed with sound absorbing material.
  • the annular chamber between the walls 18a and 18b acts as a noise attenuating chamber.
  • FIG. 1A the silencer shown therein embodies the principles of Figure 1 in a practical form. Parts of this silencer which correspond to the same parts of Figure 1 have been given the same reference numbers as in Figure 1.
  • respective inner and outer chambers 12, 13 define between them an annular passage into which the gases entering at 11 and impinging on the end wall 14 are forced to flow and are then funnelled down into the cone 16 and swirlaround against the perforated downstream end wall 15 to flow along the exhaust tube 17 which is perforated and surrounded by sound absorbing material.
  • the end wall 14 of the inner chamber is a streamlined cone, and the annular passage is noticeably short.
  • the inner chamber 13 is held coaxially within the outer chamber 12 by three equally circumferentially spaced supporting webs 19.
  • the webs 19 are longitudinally streamlined so as to lessen their resistance to the gas flow around them.
  • the silencer of Figure 1A is remarkably short. It takes up relatively little space, whilst achieving a very acceptable ndse attenuation.
  • Non-public tests indicate that the silencer of Figure 1A fitted to a Bedford Model 500 sixteen ton lorry powered by a 150 brake horsepower diesel engine reduced the engine noise level at exhaust below the legal limit, whilst giving a substantial fuel saving of the order of 11 or 12% over the silencer fitted as standard to the lorry.
  • Figure 2 illustrates a silencer which is similar to that of Figure 1A but which includes a third . section inbetween the annular passage section and the perforated exhaust tube.
  • This third section consists of inner and outer chambers respectively 21, 22 which are so sized that the inner chamber 21 joins or fits within the perforated exhaust tube 17; whilst the outer chamber 22 fits closely within the chamber 12 of the annular passage section.
  • the silencer can thus very easily be taken apart into its three component sections.
  • the tube 21 is split, part way along its length, by an annular gap 23 which is surrounded by and opens into the expansion chamber defined between the two tubes 21, 22.
  • the perforated end wall 15 of the inner chamber 13 has a minimum of 40% of its surface area perforated.
  • the effect of the additional intermediate section 21, 22 is to cut out very deep resonant notes.
  • the whole silencer is only just over 31 ⁇ 2 feet long, yet non-public tests with the silencer fitted to a Daimler Ileetline bus powered by a Gardner 6LXB diesel engine resulted in an abnormally quiet exhaust.
  • the back pressure in-this silencer was only 1 ⁇ 2" water gauge - approximately half the value obtained on tickover with the standard silencer supplied with the engine.
  • the standard silencer indicated 14" water gauge pressure at exhaust: the silencer of Figure 2 indicated only 4" water gauge pressure whilst cutting out almost entirely the deep resonant notes which the standard silencer is unable to get rid of.
  • the silencers described so far are intended for use with diesel engines.
  • the silencer illustrated in Figures 3 and 4 is, by comparison, intended for use with a petrol engine.
  • Non-public tests of one such silencer have been carried out. The following results were observed.
  • the silencer of Figures 3 and 4 was fitted to a Ford Granada motor car powered by a 2 litre petrol engine.
  • the standard silencer of this car is in two successive sections, which are separate from one another and are in the form of elliptical boxes filled with sound absorbing material.
  • the gas flow from the first box is led to the second box by a length of standard tubing.
  • annular passage silencer shown in Figure 3 replaced the first of the boxes, whilst the perforated exhaust portion shown in Figure 4 replaced the second box.
  • the composite silencer thus embodied the principles of the invention, but instead of the two portions being joined directly to one another they were joined by the length of tubing previously mentioned.
  • the standard silencer indicated 1" water gauge pressure
  • the illustrated silencer indicated 1 ⁇ 4" water gauge pressure.
  • the standard silencer indicated 11 ⁇ 2" water gauge pressure at exhaust
  • the illustrated silencer indicated 1" water gauge pressure at exhaust.
  • the standard silencer indicated 31 ⁇ 2" water gauge pressure at exhaust
  • the illustrated silencer indicated 21 ⁇ 2" water gauge pressure at exhaust.
  • the noise attenuation given by the illustrated silencer was at least comparable with that given by the standard silencer.
  • the invention is applicable to a wide range of situations and results in acceptable noise attenuation whilst absorbing remarkably little of the power generated by the engine to which it is fitted.
  • silencers embodying the invention are compact and simple in construction, and are likely to weigh no more than silencers of conventional type.

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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)
EP79301033A 1979-04-10 1979-06-01 Abgasschalldämpfer für einen Motor Withdrawn EP0020823A1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP79301033A EP0020823A1 (de) 1979-04-10 1979-06-01 Abgasschalldämpfer für einen Motor

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IE36679A IE790366L (en) 1979-04-10 1979-04-10 Engine exhaust silencer
EP79301033A EP0020823A1 (de) 1979-04-10 1979-06-01 Abgasschalldämpfer für einen Motor

Publications (1)

Publication Number Publication Date
EP0020823A1 true EP0020823A1 (de) 1981-01-07

Family

ID=26078043

Family Applications (1)

Application Number Title Priority Date Filing Date
EP79301033A Withdrawn EP0020823A1 (de) 1979-04-10 1979-06-01 Abgasschalldämpfer für einen Motor

Country Status (1)

Country Link
EP (1) EP0020823A1 (de)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1994018438A1 (en) * 1993-02-01 1994-08-18 Silentor A/S A silencer
WO1995005565A1 (en) * 1993-08-13 1995-02-23 Bröderna Rasch Ab Silent regulating valve
GB2302707B (en) * 1995-04-07 1998-12-09 David Kent Four-outlet exhaust systems for the full range of Lotus Esprit (RTM) vehicles to improve looks, improve sound and increase power
FR2854427A1 (fr) * 2003-04-29 2004-11-05 Mig Production Silencieux pour gaz d'echappement de moteurs a combustion interne.
EP4053393A1 (de) * 2017-07-19 2022-09-07 Garrett Transportation I Inc. Schalldämpfer mit barriereelement zur dämpfung von akustischer energie, die sich in einem gasstrom stromaufwärts ausbreitet

Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR700164A (fr) * 1929-08-10 1931-02-25 Perfectionnements aux silencieux pour échappement
FR822559A (fr) * 1936-09-08 1938-01-04 Perfectionnements aux silencieux
GB507213A (en) * 1937-12-09 1939-06-09 Joseph George Blanchard Improvements relating to silencers for the passage of gaseous currents
DE685996C (de) * 1938-03-08 1939-12-30 Wolfgang Zoeller Dipl Ing Schalldaempfer, insbesondere fuer Brennkraftmaschinen
FR1226438A (fr) * 1958-10-09 1960-07-11 Silencieux pour l'écoulement des fluides
DE1816848A1 (de) * 1968-12-24 1970-07-02 Lionel Fothergill Developments Auspuffschalldaempfer
GB1219404A (en) * 1967-03-30 1971-01-13 Hendry Brothers London Ltd Improvements in and relating to exhaust silencers for internal combustion engines
US3863733A (en) * 1972-04-03 1975-02-04 Skyway Machine Inc Exhaust silencer for internal combustion engine
US3989121A (en) * 1975-05-14 1976-11-02 Tenneco Inc. Pulse converting exhaust silencing system
GB2017211A (en) * 1978-01-05 1979-10-03 Glynwed Screws & Fastenings Lt Engine Exhaust Silencer

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR700164A (fr) * 1929-08-10 1931-02-25 Perfectionnements aux silencieux pour échappement
FR822559A (fr) * 1936-09-08 1938-01-04 Perfectionnements aux silencieux
GB507213A (en) * 1937-12-09 1939-06-09 Joseph George Blanchard Improvements relating to silencers for the passage of gaseous currents
DE685996C (de) * 1938-03-08 1939-12-30 Wolfgang Zoeller Dipl Ing Schalldaempfer, insbesondere fuer Brennkraftmaschinen
FR1226438A (fr) * 1958-10-09 1960-07-11 Silencieux pour l'écoulement des fluides
GB1219404A (en) * 1967-03-30 1971-01-13 Hendry Brothers London Ltd Improvements in and relating to exhaust silencers for internal combustion engines
DE1816848A1 (de) * 1968-12-24 1970-07-02 Lionel Fothergill Developments Auspuffschalldaempfer
US3863733A (en) * 1972-04-03 1975-02-04 Skyway Machine Inc Exhaust silencer for internal combustion engine
US3989121A (en) * 1975-05-14 1976-11-02 Tenneco Inc. Pulse converting exhaust silencing system
GB2017211A (en) * 1978-01-05 1979-10-03 Glynwed Screws & Fastenings Lt Engine Exhaust Silencer

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1994018438A1 (en) * 1993-02-01 1994-08-18 Silentor A/S A silencer
WO1995005565A1 (en) * 1993-08-13 1995-02-23 Bröderna Rasch Ab Silent regulating valve
GB2302707B (en) * 1995-04-07 1998-12-09 David Kent Four-outlet exhaust systems for the full range of Lotus Esprit (RTM) vehicles to improve looks, improve sound and increase power
FR2854427A1 (fr) * 2003-04-29 2004-11-05 Mig Production Silencieux pour gaz d'echappement de moteurs a combustion interne.
EP4053393A1 (de) * 2017-07-19 2022-09-07 Garrett Transportation I Inc. Schalldämpfer mit barriereelement zur dämpfung von akustischer energie, die sich in einem gasstrom stromaufwärts ausbreitet

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PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

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Effective date: 19810703

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Effective date: 19830107