Exhaust system of multi-cylinder internal combustion engine

Abstract

PROBLEM TO BE SOLVED: To enable early activation by arranging a bypass catalytic converter 18 on the further upstream side for performing exhaust emission control just after a cold start. SOLUTION: An upstream side main passage 2 is connected with every cylinder 1, and mutual cylinders uncontinuous in an exhaust stroke are merged as an intermediate main passage 3, and finally become one downstream side main passage 7. A main catalytic converter 8 is interposed in the middle of the downstream side main passage 7. A selector valve 4 is interposed between the upstream side main passage 2 and the intermediate main passage 3. As a bypass flow passage, an upstream side bypass passage 11 branches off from the respective upstream side main passages 2, and the mutual adjacent cylinders are merged as an intermediate bypass passage 14, and finally become one downstream side bypass passage 16. The bypass catalytic converter 18 is interposed in the middle of a downstream side bypass passage 16. The bypass catalytic converter 18 is maximally arranged on the upstream side in the bypass flow passage. COPYRIGHT: (C)2006,JPO&NCIPI

Description

technical field [0001] The present invention relates generally to an exhaust system of a multi-cylinder internal combustion engine having a catalytic converter for purifying exhaust gases from the engine. And in particular to exhaust systems of the type having a main catalytic converter and an auxiliary catalytic converter, wherein the main catalytic converter is not activated sufficiently and the exhaust gases are directed to the Easy-to-trigger secondary catalytic converter. Background technique [0002] Typically, in a motor vehicle powered by an internal combustion engine, the exhaust system of the engine is arranged under the floor of the vehicle, and a catalytic converter is installed in the exhaust system. If the catalytic converter is arranged at a relatively downstream position of the system, it takes a long time for the catalytic converter to be heated to a sufficient extent for its exhaust gas cleaning operation, especially immediately after the engine is started...

AI Technical Summary

Problems solved by technology

That is to say, for a long time, the catalytic converter cannot show its normal exhaust gas purification effect.

However, if the catalytic converter is arranged at a relatively upstream position in the system, i.e., close to the engine, in order to solve the above-mentioned disadvantages, it tends to produce another disadvantage, namely, due to the thermal shock of the engine and the highly heated exhaust gas, the durability of the catalytic converter will be reduced

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