Abstract: An engine having an even number of cylinders is caused to produce two differently composed exhaust gases, one rich in air and the other in unburned fuel and CO, from the two groups of cylinders each consisting of half the number of cylinders being fired in succession, which exhaust gases are fed separately to a thermal reactor and allowed to gradually mix with each other for mild and slow reaction therein.

Abstract: An exhaust cleaning system for use with an automotive multiple-cylinder internal combustion engine including first and second groups of engine cylinders which are to be alternately fired, comprising a thermal reactor composed of an outer tubular structure formed with a first group of exhaust inlet ports leading from the first group of engine cylinders and a second group of exhaust inlet ports leading from the second group of engine cylinders, an inner tubular structure positioned within the outer tubular structure and formed with openings, and at least one air-injection nozzle opening in a longitudinal end portion of the interior or a re-combustion chamber of the inner tubular structure, wherein exhaust gases from each of the first group of engine cylinder are fired in the vicinity of the nozzle openings with the agency of secondary air injected from the nozzle and exhaust gases from each of the second group of engine cylinders are fired by the resultant hot gases advancing through a hot zone of the re-combus

Abstract: Two differently composed exhaust gases, one rich in air and the other in unburned fuel and CO, are alternately supplied to a thermal reactor in dependence on the firing sequence of engine cylinders. The thermal reactor is made up of a cylindrical inner body directly connected to an exhaust manifold at its middle and provided with exhaust holes in both ends, and an outer body forming a space between the two bodies.