Method of assembling a catalytic converter for use in an internal combustion engine

#1. Field of the Invention

#The invention relates to a process for the production of catalytic converters for purifying exhaust gases, and more particularly to a method for producing the catalytic converter comprising pre-forming the metal shell and compressing the supporting mat material against the metal shell.

#2. Description of the Related Art

#FIG. 1A is a schematic longitudinal sectional view of a catalytic converter, having a honeycomb structure, made in accordance with the method described herein;

#FIG. 1B is a cross-sectional view of the converter of FIG. 1 taken along the section line A—A;

#FIGS. 2A-2B are cross-sectional illustrations of the formation stages of a first embodiment of the instant method of assembling a catalytic converter;

#The present invention relates to a process of assembling catalytic converters, and more particularly to a method of assembling catalytic converters which achieves a compressive load upon the honeycomb structure that is sufficient to retain, but not damage the retained honeycomb substrate, and which only subjects the ceramic substrate to mat release compression which is far less intensive than the compression the substrate is subject to in the prior art methods of assembling catalytic converters. Stated differently, the instant process avoids subjecting the honeycomb substrate to the normally high pressure compressive force peaks that are typical in the standard compression methods of forming catalytic converters.

#FIGS. 1A and 1B, illustrate a typical catalytic converter comprising a ceramic honeycomb structure which functions as the catalyst structure or carrier. The catalytic converter 10 comprises a cylindrical ceramic honeycomb 12 and metal casing/shell or can 14 enclosing the same. Metal shell 14 is formed of a material capable of resisting under-car salt, temperature and corrosion; ferritic stainless steels including grades SS-409, SS-439, and more recently SS-441 are however, generally preferred. The choice of material depends on the type of gas, the maximum temperature and the like. Honeycomb 12 is formed by extruding a ceramic material such as cordierite. Metal shell 14 has inlet and outlet ports 16 and 18 and a main body portion 20. Gas introduced through inlet port flows through individual cells of honeycomb 12 and out through outlet port 18.

#Ceramic honeycomb 12, has square cells, although the cells of the honeycomb may have shapes other than square, including triangular, rectangular and the like. In consideration of the tooling costs for extrusion molding or the like, however the cells are generally square in shape.