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
  • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
  • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
  • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
  • F01N3/24—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by constructional aspects of converting apparatus
  • F01N3/28—Construction of catalytic reactors
  • F01N3/2839—Arrangements for mounting catalyst support in housing, e.g. with means for compensating thermal expansion or vibration
  • F01N3/2853—Arrangements for mounting catalyst support in housing, e.g. with means for compensating thermal expansion or vibration using mats or gaskets between catalyst body and housing

Definitions

• the current automotive catalytic converter systems are comprised of several components made from different materials having different properties but generally consisting of an external metal enclosure within which is a metal pipe carrying the hot engine exhaust gases linked to a multi-chambered ceramic monolithic block or blocks, the chambers of which contain the catalytic agents which cause the toxic exhaust fumes to undergo the various reactions required to oxidise the carbon monoxide and hydrocarbon components of the exhaust gas and reduce the oxides of nitrogen to non-toxic levels.
• the metal pipe carrying the hot engine exhaust gases and the metal enclosure system are subject to large and rapid dimensional expansions during the heating up period between the initial production of hot engine exhaust gases and steady state operating temperatures being reached under normal automotive operating conditions.
• the ceramic monolithic block In direct contrast to the metal components the ceramic monolithic block, by virtue of its composition and construction, undergoes very little dimensional change during both the heating up period or the high temperatures reached under normal automotive operating conditions.
• this reconciliation is achieved by affixing a conical diffuser to the circular exhaust pipe, at entry to the catalytic converter assembly, such that the conical diffuser has a circular cross section at the junction with the engine exhaust pipe and changes to an oval cross section at the point of connection to the ceramic monolithic block, the shape and internal cross section of the large diameter of the metal cone being identical to that of one face of the ceramic monolithic block.
• a length of thin ceramic material in the form of an adhesive tape, is applied such that it adheres equally to both the external edge of the metal cone and the ceramic monolithic block and extends around the full circumference of both components to form a complete seal.
• a layer of ceramic intumescent material is then applied to the external surface of the monolithic block and wrapped around it such that the monolithic block is totally enclosed circumferentially within the intumescent material.
• the length of the enclosure of the intumescent material is such that it projects beyond one edge of the ceramic monolithic block to also enclose the adhesive ceramic tape used to provide a gas tight seal between the metal cone and the ceramic monolithic block.
• the intumescent ceramic material utilised to enclose the monolithic block and joint area with the metal cone has the property of rapid dimensional expansion when subjected to temperatures above 350°C and the purpose of its use within the catalytic converter enclosure is to provide both support for the ceramic monolithic block and a sealing medium between the outer circumference of the monolithic block and the internal surface of the metal enclosure system.
• the present invention relates to the use of a profiled knitted metal wire mesh ring interposed between the end of the fixed metal cone and the nearest face of the ceramic monolithic block of such a shape and configuration that it serves to hold the said metal cone and monolithic block in correct axial alignment, to ensure the optimum flow of the hot engine exhaust gases from the metal cone into the monolithic block such that the correct catalytic reactions may occur, and also interposes a flexible portion of the said shape and configuration between the edge of the metal cone and the face of the ceramic monolithic block such that thermal expansion of the metal cone linearly towards the face of the ceramic block is compensated for without permitting the two components to make contact and cause damage one to the other.
• said knitted metal wire mesh ring providing axial alignment of the monolithic ceramic block to the metal cone it also provides a means of supporting the monolithic ceramic block from the fixed metal cone.
• the knitted metal wire mesh ring is formed by joining together the two ends of a length of knitted wire mesh sleeve to form an endless ring and then forming the ring into a 'Tee' shape by means of appropriate tools such that the upper cross member of the 'Tee' is both more flexible and greater in width than the shortened downward member of the 'Tee' which is thickened into square or rectangular form of greater rigidity than the mesh constituting the upper member.
• the inner circumference of the flat flexible component of the 'Tee' shaped ring is such that it matches the outer circumference of both the metal cone and the ceramic monolithic block.
• the 'Tee' shaped knitted metal wire mesh ring may be placed into position over the largest end of the metal cone such that the thickened section of the 'Tee' shape abuts to the edge of the end of the metal cone and one portion of the more flexible upper cross member of the 'Tee' shape circumferentially overlaps and grips a short length of the end of the metallic cone so forming a recessed socket into which the ceramic monolithic block may be accurately placed.
• the knitted metal wire mesh ring may firstly be located onto one face of the ceramic monolithic block and the metal cone located into the recessed socket so formed.

Landscapes

• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• Health & Medical Sciences (AREA)
• Toxicology (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Exhaust Gas After Treatment (AREA)

Applications Claiming Priority (2)

Publications (2)

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Family Applications (1)

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Family Cites Families (5)

• 1997
  • 1997-08-05 GB GBGB9716500.5A patent/GB9716500D0/en active Pending
  • 1997-08-15 EP EP97306237A patent/EP0896135A3/fr not_active Withdrawn

Non-Patent Citations (1)

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