US3493076A - Apparatus for smoothing pressure variations in gaseous flow - Google Patents

Apparatus for smoothing pressure variations in gaseous flow Download PDF

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Publication number
US3493076A
US3493076A US777827A US3493076DA US3493076A US 3493076 A US3493076 A US 3493076A US 777827 A US777827 A US 777827A US 3493076D A US3493076D A US 3493076DA US 3493076 A US3493076 A US 3493076A
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Prior art keywords
pressure
gases
deformable
wall
flow
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Expired - Lifetime
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US777827A
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English (en)
Inventor
Roger Marduel
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Rhone Poulenc SA
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Rhone Poulenc SA
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16J—PISTONS; CYLINDERS; SEALINGS
    • F16J3/00—Diaphragms; Bellows; Bellows pistons
    • F16J3/04—Bellows
    • F16J3/041—Non-metallic bellows
    • 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
    • F01N1/16—Silencing apparatus characterised by method of silencing by using movable parts
    • F01N1/22—Silencing apparatus characterised by method of silencing by using movable parts the parts being resilient walls
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
    • F16L55/00—Devices or appurtenances for use in, or in connection with, pipes or pipe systems
    • F16L55/04—Devices damping pulsations or vibrations in fluids

Definitions

  • the invention provides apparatus, e.g., a silencer for an engine or compressor, for smoothing pressure variations in gaseous flow, in which a tubular body is provided with a portion, e. g., a bellows portion, which is elastically deformable under the influence of pressure pulses in the gas, bafiles extending inwardly from the walls of the body.
  • the present invention relates to an apparatus for smoothing pressure variations in gaseous fiow. It is particularly suitable for smoothing variations in pressure in the exhaust of gases from internal combustion engines, i.e., it is suitable as a silencer.
  • gaseous flows can show sudden variations, for example, because of the abrupt opening of cocks, poppet valves or valves, and certain gaseous streams can have a pulsatory character, for example in a conduit in which pulsatory flow conditions are established or in gaseous streams leaving apparatus which themselves set up pulsating streams, such as piston-type compressors or internal combustion engines.
  • apparatus for smoothing pressure variations in gaseous flow comprising a tubular wall, having an inlet and an outlet, at least a portion of said wall being elastically deformable under the influence of variations in dynamic pressure, substantially proportionally to such variations, and axially spaced apart baflies extending inwardly from the deformable portions of the wall, said baflies leaving a free passage for the flow of gas having an area equal to at least half of the cross-sectional area of the deformable portion of the tubular wall at the location of such baflie.
  • the deformable portion may, for example, be formed of an elastomeric plastics material and this provides a very light arrangement which will smooth the variations in pressure in the gaseous flow and which can be used for gases up to a temperature capable of reaching 300 C., of which the chemical inertia eliminates almost completely the dangers of corrosion and introducing only a pressure drop which can be ignored under existing practical conditions.
  • the most important application of the apparatus according to the invention is a silencer for an internal combustion engine and more especially a silencer for automobile vehicles.
  • the silencer includes a tubular body or wall comprising a substantially cylindrical inlet part 1 adapted to be fitted over an engine exhaust manifold M, the inlet part being joined to a portion 2 of which the wall is deformable, the latter part being itself joined to a rigid portion including a substantially cylindrical part 3, which is followed by a shaped part 4 and a substantially cylindrical outlet part 5 adapted to be fitted over a gas exhaust pipe E.
  • the portion 2 with a deformable wall is provided with batfles 6, 7 and 8 which are rigidly fixed and which close off a part of the passage for the gases.
  • At least the deformable part is made of an elastic material preferably based on a silicone elastomer and which is resistant to the action of the exhaust gases.
  • the bafiies can be made of any material which is resistant to the action of the gases and capable of being secured to the deformable wall portion, and are preferably made of a material based on a silicone elastomer, which may or may not be reinforced.
  • the entire assembly is preferably made of silicone elastomer, it being possible for each part to be reinforced by any constructional elements for giving thermal and mechanical resistance and an elasticity which are appropriate to the function required of this part.
  • each part is not critical and they are to be determined in accordance with the usual rules in connection with the mechanical construction, depending on the number of cylinders and the rating of the engine to be equipped.
  • the baffles are of such dimensions and number that, when they are dispensed substantially perpendicular to the general direction of the flow, none of them forms an aerodynamic screen for the following baflie.
  • the bafiies can be annular, with the internal diameter decreasing in the general direction of flow of the gases.
  • the bafiies are simple circular segments which close off at a maximum half of the flow section for the gases and are disposed alternately on each side of the axis of the apparatus.
  • a deformable compartment is provided by the space defined by the various baffles.
  • the pressure differences between the peak and the trough and the pulse are reduced on passing each of the bafiles, and after passing through a suflicient number of baffles an equalisation of the pressure and a nearly constant flow rate is obtained.
  • the inherent elasticity of the material which forms the wall can be utilised, but it is possible easily to have an influence on the elastic deformation of each compartment by making the deformable wall in the form of a bellows having helical corrugations and by embedding in these corrugations one or more helically wound elastic metal wires, for example, by incorporating therein one or more steel wires which are helically wound.
  • the bafiies can be a simple prolongation of the edges of certain internal corrugations and can frequently coincide with the actual edge of these corrugations, this being particularly the case with conical bellows.
  • the cylindrical part 3 can optionally be separately made and a different material can be employed if desired.
  • a metal sleeve it is possible to use a metal sleeve.
  • part-cylindrical and part-profiled or shaped assembly provides a steadying chamber and the adoption of profiles of double curvature which are conventional in connection with combustion chambers of rockets contributes to providing a regular flow of the discharging gases with high ejection velocities.
  • the adoption for this part of the same formative material as that of the elastically deformable part, but duly reinforced so as to ensure the preservation of the shape, permits a slight elasticity for the assembly, which contributes to the damping of vibrations at sonic frequency, which could exist in the flow.
  • this part could be provided with an absorbent lining, such as silicone foams or various forms of roughening in order to provide the maintenance of an appropriate boundary layer or vibration damping zones, but this is generally unnecessary, as it is preferred to keep a smooth internal wall with a curvature providing a regular flow.
  • an absorbent lining such as silicone foams or various forms of roughening
  • the damping arrangement may be enclosed in a tight metal tube in which will be set up a pressure of the same order of magnitude as that existing in the piping system, and this will enable a sufiicient thinness and flexibility to be retained for the deformable wall.
  • the arrangement according to the invention can be constructed in monobloc form or in several parts which are assembled in the manner which is judged to be most suitable.
  • it can be constructed in the form of longitudinally assembled half shells.
  • the apparatus can be constructed in accordance with the techniques which are usual for the material being employed, such as molding, coating, shaping under vacuum or under pressure.
  • material capable of being used for the construction of apparatus according to the invention it is possible to employ any material which is resistant to the action of the gases and which offers a sufficient mechanical resistance and elasticity.
  • metals can be used and in some other cases elastomers, such as natural or synthetic rubbers, which are possibly cloth-covered or reinforced.
  • fluorinated elastomers and more particularly the fiuorinated silicone elastomers or pure silicone elastomers or the conventional silicone elastomers which are prepared from resins having linear chains of structure:
  • the linear chain can also be formed from siliconearylene linkages, which are known to provide temperature resistance, for example, chains of structure:
  • compositions of the elastomers which use these resins are well-known.
  • the compositions which are preferred are those which withstand the highest temperatures, and vulcanise either under heat or at ambient temperature.
  • the silicone elastomers which are particularly suitable are those comprising an organopolysiloxane resin of an average molecular weight of the order of 450,000 and of the general formula in which the radicals R to R represent straight or branched alkyl radicals comprising 1 to 4 carbon atoms, alkenyl radicals with 2 to 4 carbon atoms, an aromatic radical or a cycloalkyl radical comprising 3 to 6 carbon atoms, it being possible for these radicals to be substituted with one or more alkyl groupings comprising from 1 to 4 carbon atoms or one or more halogen atoms such as fluorine and an organophilic silicic filler such as silica of combustion, these resins being crosslinked by a vulcanising agent of the benzoyl peroxide type.
  • the radicals R to R represent straight or branched alkyl radicals comprising 1 to 4 carbon atoms, alkenyl radicals with 2 to 4 carbon atoms, an aromatic radical or a cycloal
  • reinforcing material designed to provide the desired mechanical resistance or elasticity for a particular part of the arrangement according to the invention, it is possible to employ any material which is usual in the manufacture of objects which are based on elastomers, such as fabrics, glass fabrics, metal cloths or others. It is also possible to employ local reinforcing elements, such as metal plates, steel wires or the like.
  • a very satisfactory material baflle is a silicone elastomer which is resistant to high temperatures, is reinforced with a metal cloth embedded in the mass or even in the form of a metal plate adhesively bonded to the elastic wall consisting of silicone resin by means of a silicone resin vulcanised in position.
  • EXAMPLE An automobile vehicle having a 4-cy1inder engine with a cylinder capacity of 1468 cc. is used, the engine under normal running conditions turning between 1000 rpm. and 5000 r.p.m
  • a silencer as illustrated in the figure is disposed between the pipe leading from the engine exhaust manifold and the exhaust pipe.
  • the elastically deformable part is a bellows made from a silicone elastomer with a molecular weight of 450,000 and of the formula:
  • the bellows has annular corrugations, the depth of the folds of the corrugations being 10 mm.; the bellows has 20 corrugations, its minimum diameter, at the entry end for the gases, being 80 mm. and its maximum diameter is 130 mm., while the total length is 300 mm. It is connected by a cylindrical part to pipe M with a diameter of 30 mm.
  • This bellows is followed by a cylindrical part with a diameter of 130 mm. and a length of 50 mm., which is followed by a part having a double curvature and a length of 500 mm., which is terminated by a cylindrical part with a diameter of 40 mm. and a length of 50 mm., which is connected to the exhaust pipe E of the vehicle.
  • the part having double curvature consists of an identical silicone elastomer reinforced with glass fabric and made rigid by a helical steel wire of 0.5 mm., diameter of which the turns are spaced at 10 mm.
  • the silencer assembly has a total length of 800 mm., without the short connecting pipes.
  • the bellows 2 carries three regularly spaced alternate semi-circular batfies consisting of a silicone elastomer of a similar general formula, but carrying phenyl radicals in place of the methyl radicals. These partitions are adhesively bonded to the bellows by a cold-vulcanising silicone elastomer.
  • the gases have the following temperatures; discharge temperature of the gases at the exhaust pipe when the motor is running extremely slowly is 38 C., after acceleration for 10 minutes it is 131 C.
  • the assembly behaves very satisfactorily mechanically and as regards withstanding the products of combustion.
  • the assembly is very light weighing only 600 g. and it does not require any mechanical fixing to the bodywork. It withstands perfectly the external climatic conditions.
  • a metal silencer of conventional type for a vehicle of this type weighs 5 kg.
  • Apparatus for smoothing pressure variations in gaseous flow comprising, in combination:
  • baffles extending inwardly from said deformable portion of said wall, and defining with said portion a reduced area for gaseous flow, said reduced area being at least half the area defined by said tubular wall at the location of each 'bafile.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Exhaust Silencers (AREA)
  • Pipe Accessories (AREA)
US777827A 1967-11-21 1968-11-21 Apparatus for smoothing pressure variations in gaseous flow Expired - Lifetime US3493076A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR129061 1967-11-21

Publications (1)

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US3493076A true US3493076A (en) 1970-02-03

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US777827A Expired - Lifetime US3493076A (en) 1967-11-21 1968-11-21 Apparatus for smoothing pressure variations in gaseous flow

Country Status (8)

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US (1) US3493076A (zh)
BE (1) BE724186A (zh)
DE (2) DE1810158A1 (zh)
FR (1) FR1554785A (zh)
GB (1) GB1206307A (zh)
LU (1) LU57351A1 (zh)
NL (1) NL6816161A (zh)
SE (1) SE341410B (zh)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20080196386A1 (en) * 2005-04-29 2008-08-21 Marco Ranalli Connection Element Arranged Between a Housing and an Exhaust Pipe
US20080233856A1 (en) * 2007-03-22 2008-09-25 Toyoda Gosei Co., Ltd. Air conditioner duct
CN107218108A (zh) * 2017-05-22 2017-09-29 东南大学 一种宽频带高频噪声消声单元

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2288217A1 (fr) * 1974-10-14 1976-05-14 Martinez Ginez Echappement reducteur de bruit pour moteur a combustion interne
US4439104A (en) * 1981-06-15 1984-03-27 The Garrett Corporation Compressor inlet guide vane and vortex-disturbing member assembly
US4844695A (en) * 1988-07-05 1989-07-04 Pratt & Whitney Canada Inc. Variable flow radial compressor inlet flow fences
US5373691A (en) * 1993-06-23 1994-12-20 Allied-Signal Inc. Inlet guide vane dewhistler
FR2884861A1 (fr) * 2005-04-26 2006-10-27 Yngve Jakobsen Pot d'echappement realise en caoutchouc synthetique pour moteurs a combustion interne deux ou quatre temps
DE102021001997A1 (de) * 2020-04-23 2021-10-28 Löwenstein Medical Technology S.A. Beatmungsgerät zur Beatmung eines Lebewesens

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US781939A (en) * 1903-02-26 1905-02-07 Weston M Fulton Collapsible vessel.
US2233804A (en) * 1938-07-18 1941-03-04 Maxim Silencer Co Fluid silencer
US3061039A (en) * 1957-11-14 1962-10-30 Joseph J Mascuch Fluid line sound-absorbing structures
US3187837A (en) * 1963-08-28 1965-06-08 Charles G Beeching Free flow acoustic silencer constructed of resilient material

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US781939A (en) * 1903-02-26 1905-02-07 Weston M Fulton Collapsible vessel.
US2233804A (en) * 1938-07-18 1941-03-04 Maxim Silencer Co Fluid silencer
US3061039A (en) * 1957-11-14 1962-10-30 Joseph J Mascuch Fluid line sound-absorbing structures
US3187837A (en) * 1963-08-28 1965-06-08 Charles G Beeching Free flow acoustic silencer constructed of resilient material

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20080196386A1 (en) * 2005-04-29 2008-08-21 Marco Ranalli Connection Element Arranged Between a Housing and an Exhaust Pipe
US20080233856A1 (en) * 2007-03-22 2008-09-25 Toyoda Gosei Co., Ltd. Air conditioner duct
CN107218108A (zh) * 2017-05-22 2017-09-29 东南大学 一种宽频带高频噪声消声单元

Also Published As

Publication number Publication date
DE6807969U (de) 1972-01-20
LU57351A1 (zh) 1969-07-04
BE724186A (zh) 1969-05-20
FR1554785A (zh) 1969-01-24
DE1810158A1 (de) 1969-07-31
GB1206307A (en) 1970-09-23
NL6816161A (zh) 1969-05-23
SE341410B (zh) 1971-12-27

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