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
  • F01N13/10—Other arrangements or adaptations of exhaust conduits of exhaust manifolds
• • 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
  • F01N13/14—Exhaust or silencing apparatus characterised by constructional features having thermal insulation
• • 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
  • F01N13/10—Other arrangements or adaptations of exhaust conduits of exhaust manifolds
  • F01N13/102—Other arrangements or adaptations of exhaust conduits of exhaust manifolds having thermal insulation
• • 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
  • F01N13/16—Selection of particular 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
  • F01N2310/00—Selection of sound absorbing or insulating material
  • F01N2310/02—Mineral wool, e.g. glass wool, rock wool, asbestos or the like

Definitions

• the present invention relates to an exhaust duct comprising, arranged concentrically:
• the elements of the exhaust line between the engine outlet and the pollution control members comprise an inner ceramic tube surrounded by an outer tube of metal between which is interposed an insulating material.
• the ceramic tube because of its low thermal inertia, greatly reduces the heat transfer of the exhaust gas to the ceramic tube.
• the low thermal expansion of the inner ceramic tube makes it possible to produce single-piece internal pipes even for engines that release exhaust gases at very high temperatures, in particular greater than 1000 ° C. without risk of thermomechanical rupture.
• Such a structure is used in particular in the exhaust manifolds provided immediately at the output of the engine.
• a relatively thick, thermally insulating layer of ceramic fibers in contact with the ceramic tube.
• the thick layer of ceramic fibers has a thickness of between 1 mm and 40 mm and preferably between 2 mm and 20 mm.
• a so-called thin layer of stress isolation is provided between the thick layer of ceramic fiber and the outer tube of metal. This thin layer of stress isolation is between 0.05 mm and 2 mm and preferably between 0.1 mm and 0.5 mm. This layer of stress insulation is designed to absorb the vibrations of the engine and the road to prevent the destruction of the thick ceramic fiber layer.
• This layer also attenuates the vibrations, in particular by compensating the differential thermal expansions between the thick ceramic fiber layer and the outer metal tube during heating of the exhaust line. Indeed, when the inner tube is traversed by gases at high temperatures, there are significant differential thermal expansions because the dense inner ceramic tube and the thick layer of ceramic fibers have relatively low expansion coefficients in comparison with the outer tube made of metal.
• US 6,725,658 thus describes a multilayer structure comprising at least a dense ceramic inner layer, a thermally insulating thick layer of ceramic fibers and a metal layer. This structure is optionally supplemented by a thin layer of stress insulation for protecting the thick layer of ceramic fibers from vibrations.
• an object of the invention is an exhaust duct for satisfactory heat delivery comprising an inorganic matrix composite inner pipe held in an outer metal structure.
• the subject of the invention is an exhaust duct of the aforementioned type, characterized in that the thickness of the holding layer is between 2 mm and 10 mm, and preferably between 3 mm and 6 mm, and in that the minimum holding pressure exerted by the retaining layer on the inner tube is between 10 -4 MPa and 10 -1 MPa.
• the duct below comprises one or more of the characteristics following:
• the minimum holding pressure exerted by the retaining layer on the inner tube is between 10 3 MPa and 5 ⁇ 10 -2 MPa
• the outer metal tube has a thickness of between 0.5 mm and 3 mm
• the outer metal tube is chosen from the group consisting of a steel tube, an aluminum tube and a titanium tube,
• the outer tube is formed of two half-shells in the form of gutters assembled by longitudinal joints, the inner tube of inorganic matrix composite has a thickness of less than 2 mm,
• the inorganic matrix composite internal tube comprises a matrix consisting of at least one inorganic polymer
• the inorganic polymer is a geopolymer based on aluminosilicate
• the inorganic matrix composite internal tube comprises a matrix reinforced with fibers, in particular based on silicon carbide (SiC), carbon, silica (SiO2), or a stainless wire resistant to temperatures equal to or greater than 600 °,
• the holding layer comprises a sheet of ceramic fibers
• the holding layer comprises ceramic fibers and an inorganic binder, the holding layer comprising between 90% to 100% by weight of ceramic fibers
• the ceramic fibers are fibers selected from the group consisting of silica fibers, alumina fibers, zirconium fibers, alumina-borosilicate fibers, and mixtures thereof,
• the fibers contained in the holding layer are a mixture of alumina fibers and silica fibers in a ratio of 72 and 28% respectively,
• the GBD of the material constituting the holding layer is between 0.1 and 0.6
• the density of the material constituting the holding layer is between 500 g / m 2 and 3000 g / m 2 ,
• the coefficient of friction of the material forming the holding layer against the surfaces of the inner and outer tubes is between 0.15 and 0.7
• the exhaust manifold comprises at least one exhaust duct as defined above.
• FIG. 1 is a perspective view of an exhaust manifold according to the invention.
• FIG. 2 is a sectional view of an exhaust pipe of the manifold of FIG. 1.
• the exhaust manifold 10 illustrated in FIG. 1 is intended to be disposed at the outlet of a heat engine at the inlet. an exhaust system of a motor vehicle.
• This exhaust line comprises downstream of the collector 10, possibly a supercharging system tion (turbo) and one or more depollution elements capable of operating at high temperature.
• Turbo supercharging system tion
• the collector 10 has a plurality of inlets 12 converging towards an outlet flange 14.
• the inlets 12 are connected to the outlet flange 14 by ducts 20 opening into each other.
• each conduit 20 comprises an inner tube 22 of inorganic matrix composite, in particular ceramic, and an outer metal tube 24 between which is disposed a holding layer 26 made of a ceramic fibrous material.
• the conduit consists of only three layers 22, 24 and 26.
• the outer tube 24 is formed of a metal wall having a thickness of between 0.5 and 3 mm. According to a first embodiment, the outer tube 24 is a cylindrical metal tube including steel, aluminum or titanium.
• the outer tube 24 is formed of two metal half-shells 27 in the form of gutters joined by opposite longitudinal seals 28.
• the outer tube 24 is provided with flanges allowing its connection with, upstream, the engine and downstream, the exhaust line of the vehicle.
• the choice of an outer metal tube is justified by the need to ensure optimum sealing upstream of the pollution control elements, and in particular at the junction of the outer tube with the upstream and downstream metal flanges.
• the authorized leakage flow rate is 25 liters / hour at 20 ° C. under 1.3 bar.
• the inner tube 22 is a tube formed from a composite material with an inorganic matrix, in particular a ceramic matrix. Examples of inorganic matrix composite materials that can allow the formation of the inner tube 22 are given in patent applications US6134881 and WO2004106705. These materials are formed by the combination of a matrix consisting of at least one inorganic polymer, preferably of geopolymer type, based on aluminosilicate.
• the inner tube 22 is formed of a wall having a thickness of less than 2 mm.
• the holding layer 26 has a thickness of between
• the holding layer 26 is formed of a layer of ceramic fibers, in particular long ceramic fibers preferably associated with an organic and / or inorganic binder.
• the organic binder is only useful when placing the holding layer around the inner tube; it is consumed during the first temperature rise of the exhaust duct on the vehicle. This binder represents from 0 to 15% by weight of the new holding layer.
• the inorganic binder is used when it is necessary to ensure better cohesion between the fibers during operation of the vehicle and must not be burned.
• This binder represents from 0 to 10% by weight of the organic binder-free holding layer.
• the ceramic fibers represent 90 to 100% by weight of the holding layer, the remainder being the inorganic binder.
• the ceramic fibers present in the holding layer 26 are selected from the group consisting of silica fibers, alumina fibers, zirconium fibers, borosilicate alumina fibers and a mixture thereof.
• the sheets may be needled, which improves their behavior over time.
• the fibers used are mullite fibers combining alumina and silica in a ratio of 72% and 28%, respectively.
• the density of the material constituting the holding layer is between 500 g / m 2 and 3000 g / m 2 .
• This holding layer 26 must maintain the inner tube 22 in the outer tube 24 regardless of the operating conditions.
• the minimum pressure to be applied to maintain said inner tube in the metal tube is determined. This minimum pressure takes into account, in addition to the above mentioned solicitations, a specific corrective factor of the operating behavior of the inner ceramic tube and the holding layer. A coefficient of friction intervenes in this corrective factor.
• the material constituting the holding layer is chosen so that the coefficient of friction of the damping layer against the surfaces of the inner and outer tubes is between 0.15 and 0.7.
• the minimum holding pressure is between 10 "4 and 10" 1 MPa and preferably between 10 "3 MPa and 5.10" 2 MPa.
• the value of 10 "3 MPa corresponds to an inner tube of 100 grams having a contact area of 40 dm 2 with the holding layer subjected to an acceleration of 10 g and a pressure drop of 100 Pa. This pressure drop is induced by the friction of the gases against the wall of the inner tube
• the value of 5.10 "2 MPa corresponds to an inner tube of 200 grams having a contact surface of 20 dm 2 with the holding layer and subjected to an acceleration of 40 g and a loss charge of 250Pa.
• the value of the clearance between the outer and inner tubes is dictated in particular by the shape constraints of the exhaust line element.
• the usable GBD range is 0.1 to 0.6. The minimum value is given to avoid vibrational deterioration of the fibers, the maximum value is given to avoid deterioration of the fibers by compression.
• the GBD is 0.3.
• the holding pressure exerted by the ply on the internal ceramic matrix composite tube is then, for the chosen type of ply, 0.2 MPa.
• This GBD of 0.3 is well within the recommended GBD range. This pressure is greater than the minimum holding pressure calculated for this application (5.10 "2 MPa) and lower than the mechanical strength of the inner tube.
• the maximum clearance for this same application is 4.25 mm, corresponding to a GBD of 0.22 and a holding pressure of 6.10 "2 MPa.
• the GBD remains in the range of use of the web and the induced pressure remains greater than the minimum holding pressure. It is noted that with such an exhaust duct, the holding material correctly ensures the maintenance of the inner tube of inorganic matrix composite in the outer metal tube regardless of the temperature of the exhaust line and the flow conditions. gaseous and acceleration to which the inner tube is subjected without deteriorating or damaging the inner tube.

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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)
• Steroid Compounds (AREA)
• Valve Device For Special Equipments (AREA)
• Seal Device For Vehicle (AREA)

Applications Claiming Priority (2)

Publications (2)

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Family Applications (1)

Country Status (8)

Cited By (1)

Families Citing this family (8)

Family Cites Families (13)

• 2005
  • 2005-08-09 FR FR0508466A patent/FR2889721B1/fr not_active Expired - Fee Related
• 2006
  • 2006-08-03 JP JP2008525596A patent/JP2009504968A/ja active Pending
  • 2006-08-03 EP EP06808051A patent/EP1915519B1/de not_active Not-in-force
  • 2006-08-03 AT AT06808051T patent/ATE423896T1/de not_active IP Right Cessation
  • 2006-08-03 US US12/063,482 patent/US20090183502A1/en not_active Abandoned
  • 2006-08-03 KR KR1020087005465A patent/KR20080080980A/ko not_active Ceased
  • 2006-08-03 DE DE602006005375T patent/DE602006005375D1/de active Active
  • 2006-08-03 WO PCT/FR2006/001896 patent/WO2007017583A1/fr not_active Ceased

Non-Patent Citations (1)

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