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 ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00
  • 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 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)

Applications Claiming Priority (3)

Publications (1)

Family

ID=20283074

Family Applications (1)

Country Status (6)

Families Citing this family (10)

Family Cites Families (22)

• 2001
  • 2001-02-21 SE SE0100585A patent/SE522546C2/sv not_active IP Right Cessation
• 2002
  • 2002-02-14 EP EP02711615A patent/EP1373689A1/de not_active Withdrawn
  • 2002-02-14 JP JP2002566090A patent/JP4159032B2/ja not_active Expired - Fee Related
  • 2002-02-14 WO PCT/SE2002/000260 patent/WO2002066798A1/en not_active Application Discontinuation
  • 2002-02-14 BR BR0207389-7A patent/BR0207389A/pt not_active Application Discontinuation
• 2003
  • 2003-08-21 US US10/604,848 patent/US20040104071A1/en not_active Abandoned

Non-Patent Citations (1)

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