CATALYTIC CONVERTER COMPONENT AND PROCESS FOR ITS MANUFACTURE
In a process for manufacturing a catalytic converter component, a ceramic unit is used that has been prepared by extruding green ceramic product through a die to form an extrusion having a honeycomb substrate structure in which tubular passages extend along the extrusion, the passages bounded by walls dividing adjacent passages from one another. The unit is obtained by cutting off a length of the extrusion and curing and firing it. The process further comprises flowing insulation material as by injecting mastic insulation from one end of the unit into selected ones of the elongate passages to fill the selected passages throughout their length, the insulating material then being cured. The passages are selected so that the cured insulation material forms an internal thermal insulating barrier between a core zone of the unit and a radially outer zone of the unit.
1 . A process for manufacturing a component for a catalytic converter, comprising taking a ceramic unit prepared by extruding green ceramic product through a die to form an extrusion having a honeycomb substrate structure having a plurality of tubular passages extending along the length of the extrusion, the passages bounded by walls dividing adjacent passages from one another, the unit being obtained by cutting off a length of the extrusion and curing and firing the length of extrusion, the process further comprising flowing insulation material from one end of the unit into selected ones of the elongate passages, and curing the insulating material, the cured injected insulation material forming an internal thermally insulating barrier between a core zone of the unit and a radially outer zone of the unit.
2 . A process as claimed in claim 1 , in which the insulation material in at least some of the passages is flowed from said one end to fill the selected passages to the other end of the unit.
3 . A process as claimed in claim 1 , the insulation material including components of glass fibres, ceramic and polymer binder.
4 . A process as claimed in claim 3 , in which the insulation material is a paste-like material which is injected into the selected passages, the insulation material further including water.
5 . A process as claimed in claim 3 , in which the insulation material is a powder, the powder is directed into entrances of the selected passages and falls by gravity, and the extrusion is vibrated to encourage compaction of the powdered insulation in the passages.
6 . A process as claimed in claim 1 , in which, following curing, the cured insulating material is predominantly silica.
7 . A process as claimed in claim 1 , the curing of the insulation being effected by microwave irradiation.
8 . A process as claimed in claim 6 , the curing such as to have microwave radiation penetrate from both sides of the barrier layer.
9 . A process as claimed in claim 1 , the insulation material directed through a die to obtain a generally cylindrical thermal insulation barrier.
10 . A process as claimed in claim 1 , further comprising using a gasket layer on at least one end of the unit to limit incursion of insulation material into non-selected passages.
11 . A process as claimed in claim 1 , further comprising incrementally relatively moving an extrusion die and the unit to optimize registration of an exit aperture of the die to entrance openings of the selected passages.
12 . A component for a catalytic converter comprising a unit of cured ceramic extrusion having a honeycomb substrate structure in which a plurality of passages extends along the unit, the passages bounded by walls dividing adjacent passages from one another, selected ones of the passages filled with cured insulation material, the cured insulation material forming an internal thermal insulation barrier between a core zone of the unit and a radially outer zone.
13 . A component as claimed in claim 12 , the selected passages filled with cured, injected mastic insulation material.
14 . A component as claimed in claim 12 , the selected passages filled with cured, gravity-flowed, vibration-compacted powder insulation material.
15 . A component as claimed in claim 12 , the component mounted within a casing, the casing having an inlet adaptor for entry of exhaust gases from an upstream exhaust pipe section to one end of the component for transmission along non-selected ones of the passages, and an outlet adaptor for exit of exhaust gases from the other end of the component to a downstream exhaust pipe section after transmission thereof along said non-selected passages, the core zone having a radial size substantially equal to the bore of the upstream exhaust pipe section.