EP1373689A1 - Apparatus for damping resonance in a conduit - Google Patents

Apparatus for damping resonance in a conduit

Info

Publication number
EP1373689A1
EP1373689A1 EP02711615A EP02711615A EP1373689A1 EP 1373689 A1 EP1373689 A1 EP 1373689A1 EP 02711615 A EP02711615 A EP 02711615A EP 02711615 A EP02711615 A EP 02711615A EP 1373689 A1 EP1373689 A1 EP 1373689A1
Authority
EP
European Patent Office
Prior art keywords
conduit
perforation
pipe
sound
resonance
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Withdrawn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
EP02711615A
Other languages
German (de)
French (fr)
Inventor
Gert-Ove WAHLSTRÖM
Björn HENRIKSSON
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.)
Volvo Truck Corp
Original Assignee
Volvo Lastvagnar AB
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
Application filed by Volvo Lastvagnar AB filed Critical Volvo Lastvagnar AB
Publication of EP1373689A1 publication Critical patent/EP1373689A1/en
Withdrawn legal-status Critical Current

Links

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
    • F01N13/00—Exhaust or silencing apparatus characterised by constructional features
    • F01N13/08—Other arrangements or adaptations of exhaust conduits
    • 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
    • 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
    • F01N2470/00—Structure or shape of exhaust gas passages, pipes or tubes
    • F01N2470/02—Tubes being perforated
    • F01N2470/04—Tubes being perforated characterised by shape, disposition or dimensions of apertures

Definitions

  • the present invention relates to an apparatus for damping resonance in a conduit for transporting exhaust gases from an internal combustion engine.
  • a silencer system consists of one or more chamber (s) with intermediate conduits.
  • the sound pressure inside the conduit will vary with the position along the conduit.
  • Pipe resonance can sometimes occur in an exhaust system. What happens then is that the ignition pulses from the engine are reflected between the mouth of the exhaust pipe and a preceding part of the exhaust system, frequently that chamber in the silencer closest to the end pipe. In most cases, this only happens at a specific engine speed, where the wavelength of the ignition frequency coincides with the length between the two adjacent reflecting pipe ends.
  • One object of the invention is therefore to produce an apparatus which solves this problem, without appreciably raising the price or increasing costs.
  • the apparatus according to the invention is characterized in that the conduit is provided with at least one perforation located at a distance from the outer end of the conduit.
  • FIG 1 shows a diagrammatic plan view of a portion of a conduit designed according to a first variant of the invention
  • FIG 2 is a longitudinal section through a portion of a conduit designed according to a second variant of the invention
  • FIG 3 is a longitudinal section through a portion of a conduit designed according to a third variant of the invention
  • FIGS 4-5 show modifications of the variant of the invention shown in Fig. 2
  • FIGS 4-5 show modifications of the variant of the invention shown in Fig. 2
  • FIGS 6-7 show a part of the plate wall of the conduit in section and in a plan view respectively, with examples of different perforations.
  • the invention relates to an apparatus which can be applied to exhaust systems and silencer systems in various types of internal combustion engine, for example engines which function according to the Otto, Diesel or Wankel principles.
  • the engine can be located in a vehicle, for example a passenger car, a truck, a work vehicle or a vessel.
  • the invention can also be applied to fixed engine installations, such as engine- driven power plants and the like.
  • the apparatus can then be located in different positions along the pipe portions which form part of the exhaust and silencer systems of the engine.
  • Such a pipe portion can form, for example, the end pipe which transports exhaust gases from a silencer pot out into the surrounding environment .
  • Fig. 1 shows a pipe portion 10, curved essentially at right angles, with an outlet end 11 and an inlet end 12, the wall 13 of which has a perforation 14 on the inside of the curve.
  • the perforation connects the inner volume of the pipe to the surrounding environment .
  • Exhaust emissions through the perforation 14 can be avoided, because this is located in a part of the flow passage where the static pressure is comparatively lower than in other parts of the passage.
  • Fig. 2 shows on larger scale an alternative embodiment of the invention, in which a number of perforations 14 are made in the pipe wall 13 of a pipe section 10 with a portion 10a with a slightly reduced flow area.
  • the flow rate will increase within this portion with a reduction in the static pressure in the pipe as a consequence, which means that surrounding air can be sucked into the pipe through the perforations without exhaust gases escaping.
  • Fig. 3 shows a further variant of the invention, where an indentation 15 has been made in the pipe wall 13 in such a manner that a reduction in the flow area has been brought about in this part. Downstream of the indentation 15, the pipe wall forms a step 16 essentially at right angles out to the normal cross section. A perforation 14 is located on the downstream side of this step. An exhaust gas flow through the pipe section in Fig. 3 will increase its flow rate at the indentation 15. The reduced pressure will draw air in from the surrounding environment of the pipe via the perforation 14.
  • Another way of avoiding leakage of exhaust gases via a perforation can be to introduce a partly sound- permeable material which will serve as flow resistance.
  • This material can be applied on the outside of the pipe, inside the pipe or in the perforations themselves.
  • the material can consist of steel, another metal, glass fiber, textile material, ceramic and so forth.
  • the material can, for example, have a structure in the form of a net, unstructured or structured fabric and also porous medium.
  • Fig. 4 shows a modification of the invention where a conduit designed according to Fig. 2 has been provided with an outer sleeve 17 which covers the perforations and is provided with a large number of small perforations 18.
  • the purpose of the outer sleeve 17 is essentially to "conceal" the perforations 14.
  • the outer sleeve 17 also provides a certain damping of sound leakage via the perforations 14. This leakage can be damped further by virtue of a space 19 between the conduit 10 and the outer sleeve being filled with a suitable damping material, for example mineral wool.
  • Fig. 5 shows another modification of the invention where a conduit designed according to Fig. 2 has been provided with an internal cuff made of sound-permeable non-woven fabric.
  • the perforations 14 can be made in a number of different ways.
  • the invention comprises a hole which is usually made in a geometrical shape, for example round, square, V-shaped, slot-shaped or any other shape.
  • the apparatus according to the invention can comprise a combination of a number of pipe portions 10 arranged in series or in parallel.

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Exhaust Silencers (AREA)
  • Pipe Accessories (AREA)
  • Vibration Prevention Devices (AREA)

Abstract

The invention relates to an apparatus for damping resonance in a conduit (10) for transporting exhaust gases from an internal combustion engine. The resonance is damped by virtue of the conduit (10) being provided with at least one perforation (14) located at a distance from the outer end (11) of the conduit.

Description

C13587, 02-05-23
TITLE
Apparatus for damping resonance in a conduit
FIELD OF THE INVENTION
The present invention relates to an apparatus for damping resonance in a conduit for transporting exhaust gases from an internal combustion engine.
BACKGROUND
In most cases, a silencer system consists of one or more chamber (s) with intermediate conduits. The sound pressure inside the conduit will vary with the position along the conduit. Pipe resonance can sometimes occur in an exhaust system. What happens then is that the ignition pulses from the engine are reflected between the mouth of the exhaust pipe and a preceding part of the exhaust system, frequently that chamber in the silencer closest to the end pipe. In most cases, this only happens at a specific engine speed, where the wavelength of the ignition frequency coincides with the length between the two adjacent reflecting pipe ends.
In cases when resonance has occurred in the pipe, the differences in sound pressure will be particularly great between different positions. A high sound pressure then builds up in the end pipe, and sound escapes into the surrounding environment via the mouth to a greater extent than would otherwise have been the case. Known solutions to this problem usually involve the insertion of additional silencer units, which results in higher costs and can also lead to an increase in the pressure drop.
DISCLOSURE OF THE INVENTION
One object of the invention is therefore to produce an apparatus which solves this problem, without appreciably raising the price or increasing costs. To this end, the apparatus according to the invention is characterized in that the conduit is provided with at least one perforation located at a distance from the outer end of the conduit. By virtue of this design of the apparatus, an effective reduction in the resonance level is brought about in a simple manner.
Advantageous illustrative embodiments of the invention emerge from the following, dependent patent claims.
BRIEF DESCRIPTION OF FIGURES
The invention will be described in greater detail below with reference to illustrative embodiments shown in the accompanying drawings, in which FIG 1 shows a diagrammatic plan view of a portion of a conduit designed according to a first variant of the invention, FIG 2 is a longitudinal section through a portion of a conduit designed according to a second variant of the invention,
FIG 3 is a longitudinal section through a portion of a conduit designed according to a third variant of the invention, FIGS 4-5 show modifications of the variant of the invention shown in Fig. 2, and
FIGS 6-7 show a part of the plate wall of the conduit in section and in a plan view respectively, with examples of different perforations.
DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
The invention relates to an apparatus which can be applied to exhaust systems and silencer systems in various types of internal combustion engine, for example engines which function according to the Otto, Diesel or Wankel principles. The engine can be located in a vehicle, for example a passenger car, a truck, a work vehicle or a vessel. The invention can also be applied to fixed engine installations, such as engine- driven power plants and the like. The apparatus can then be located in different positions along the pipe portions which form part of the exhaust and silencer systems of the engine. Such a pipe portion can form, for example, the end pipe which transports exhaust gases from a silencer pot out into the surrounding environment .
Fig. 1 shows a pipe portion 10, curved essentially at right angles, with an outlet end 11 and an inlet end 12, the wall 13 of which has a perforation 14 on the inside of the curve. The perforation connects the inner volume of the pipe to the surrounding environment . When the pipe portion is mounted in an exhaust system, for example as an end pipe, and a pulsating exhaust gas flow passes through the pipe portion, resonance may occur. Some of the sound pressure in this resonance can escape to the surrounding environment via the perforation 14. This means that the size of the resonance is reduced. In this way, the escaping sound, both from the mouth and through the perforation, will occur from a significantly lower sound pressure level. Overall, a smaller amount of sound will be emitted to the surrounding environment from the exhaust system.
Exhaust emissions through the perforation 14 can be avoided, because this is located in a part of the flow passage where the static pressure is comparatively lower than in other parts of the passage.
Fig. 2 shows on larger scale an alternative embodiment of the invention, in which a number of perforations 14 are made in the pipe wall 13 of a pipe section 10 with a portion 10a with a slightly reduced flow area. In this connection, the flow rate will increase within this portion with a reduction in the static pressure in the pipe as a consequence, which means that surrounding air can be sucked into the pipe through the perforations without exhaust gases escaping. Fig. 3 shows a further variant of the invention, where an indentation 15 has been made in the pipe wall 13 in such a manner that a reduction in the flow area has been brought about in this part. Downstream of the indentation 15, the pipe wall forms a step 16 essentially at right angles out to the normal cross section. A perforation 14 is located on the downstream side of this step. An exhaust gas flow through the pipe section in Fig. 3 will increase its flow rate at the indentation 15. The reduced pressure will draw air in from the surrounding environment of the pipe via the perforation 14.
Another way of avoiding leakage of exhaust gases via a perforation can be to introduce a partly sound- permeable material which will serve as flow resistance. This material can be applied on the outside of the pipe, inside the pipe or in the perforations themselves. The material can consist of steel, another metal, glass fiber, textile material, ceramic and so forth. The material can, for example, have a structure in the form of a net, unstructured or structured fabric and also porous medium.
Fig. 4 shows a modification of the invention where a conduit designed according to Fig. 2 has been provided with an outer sleeve 17 which covers the perforations and is provided with a large number of small perforations 18. The purpose of the outer sleeve 17 is essentially to "conceal" the perforations 14. The outer sleeve 17 also provides a certain damping of sound leakage via the perforations 14. This leakage can be damped further by virtue of a space 19 between the conduit 10 and the outer sleeve being filled with a suitable damping material, for example mineral wool.
Fig. 5 shows another modification of the invention where a conduit designed according to Fig. 2 has been provided with an internal cuff made of sound-permeable non-woven fabric.
As emerges from Figs 6 and 7, the perforations 14 can be made in a number of different ways. The invention comprises a hole which is usually made in a geometrical shape, for example round, square, V-shaped, slot-shaped or any other shape.
The invention is not to be regarded as being limited to the illustrative embodiments described above, but a number of other variants and modifications are possible within the scope of the following patent claims. For example, the apparatus according to the invention can comprise a combination of a number of pipe portions 10 arranged in series or in parallel.

Claims

PATENT CLAIMS
1. An apparatus for damping resonance in a conduit (10) for transporting exhaust gases from an internal combustion engine, characterized in that that the conduit (10) is provided with at least one perforation (14) located at a distance from the outer end (11) of the conduit.
2. The apparatus as claimed in claim 1, characterized in that the perforation (14) forms an acoustic connection between the interior of the conduit (10) and the surrounding atmosphere.
3. The apparatus as claimed in claim 1 or 2, characterized in that the perforation (14) is located at a point in the conduit (10) with a comparatively lower static pressure than the pressure a little way downstream of the perforation.
4. The apparatus as claimed in claim 3, characterized in that the lower static pressure in the vicinity of the perforation (14) is brought about by means of a reduction in the cross section of the conduit.
5. The apparatus as claimed in claim 4, characterized in that the reduction in the cross section of the conduit (14) is designed as a venturi .
6. The apparatus as claimed in claim 4 or 5, characterized in that the pipe portion (10a) designed as a venturi is covered on the outside with a sound- absorbing material.
7. The apparatus as claimed in claim 6, characterized in that the sound-absorbing material is covered by a perforated plate (17) .
8. The apparatus as claimed in claim 3, characterized in that the lower static pressure in the vicinity of the perforation (14) is brought about by means of a change in direction of the gas flow in the conduit.
9. The apparatus as claimed in claim 8, characterized in that the change in direction of the gas flow is brought about by means of a curve of the conduit.
10. The apparatus as claimed in any one of the preceding claims, characterized in that the perforations (14) are covered by means of a sound- permeable fabric (20) on the inside or outside of the conduit (10) .
EP02711615A 2001-02-21 2002-02-14 Apparatus for damping resonance in a conduit Withdrawn EP1373689A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
SE0100585 2001-02-21
SE0100585A SE522546C2 (en) 2001-02-21 2001-02-21 Device for attenuating resonance in a pipeline
PCT/SE2002/000260 WO2002066798A1 (en) 2001-02-21 2002-02-14 Apparatus for damping resonance in a conduit

Publications (1)

Publication Number Publication Date
EP1373689A1 true EP1373689A1 (en) 2004-01-02

Family

ID=20283074

Family Applications (1)

Application Number Title Priority Date Filing Date
EP02711615A Withdrawn EP1373689A1 (en) 2001-02-21 2002-02-14 Apparatus for damping resonance in a conduit

Country Status (6)

Country Link
US (1) US20040104071A1 (en)
EP (1) EP1373689A1 (en)
JP (1) JP4159032B2 (en)
BR (1) BR0207389A (en)
SE (1) SE522546C2 (en)
WO (1) WO2002066798A1 (en)

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EP1524415A1 (en) * 2003-10-15 2005-04-20 Zeuna-Stärker Gmbh & Co Kg Exhaust silencer
DE102005006914B4 (en) * 2005-02-16 2008-05-29 Woco Industrietechnik Gmbh Device for sound coupling between an intake tract and / or engine compartment and a vehicle interior of a motor vehicle
JP2008151413A (en) * 2006-12-18 2008-07-03 Kumagai Gumi Co Ltd Duct parts
ITTO20070529A1 (en) * 2007-07-17 2009-01-18 Metallurg Cornaglia Sp A Off SILENCER DEVICE FOR A CONDUCT TO BE TRAVELED BY A FLUID AND ITS METHOD OF REALIZATION.
US7845465B2 (en) * 2007-08-31 2010-12-07 Tenneco Automotive Operating Company Inc. Vehicular exhaust resonator with cooling feature
US9523304B2 (en) 2013-03-11 2016-12-20 Futaba Industrial Co., Ltd. Exhaust pipe
DE102015218394A1 (en) 2015-09-24 2017-03-30 Volkswagen Aktiengesellschaft Device for preventing whistling in gas-flow systems with perforated sections
US11225897B2 (en) 2019-07-23 2022-01-18 Tenneco Automotive Operating Company Inc. Vehicle exhaust system
US11603781B2 (en) * 2020-02-03 2023-03-14 Faurecia Emissions Control Technologies, Usa, Llc Exhaust system component
US11808186B2 (en) 2021-05-12 2023-11-07 Tenneco Automotive Operating Company Inc. Surface component for vehicle exhaust system
DE102023213300A1 (en) 2022-12-28 2024-07-04 Tenneco Automotive Operating Company Inc. Vehicle exhaust system with built-in hood

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Also Published As

Publication number Publication date
SE522546C2 (en) 2004-02-17
SE0100585D0 (en) 2001-02-21
JP4159032B2 (en) 2008-10-01
SE0100585L (en) 2002-08-22
JP2004519575A (en) 2004-07-02
BR0207389A (en) 2004-02-10
WO2002066798A1 (en) 2002-08-29
US20040104071A1 (en) 2004-06-03

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