Exhaust gas recycling device and process for producing same

摘要

An exhaust gas recycling device for use in reducing the nitrogen oxide (NOx) concentration of exhaust gases from gasoline engines has between two metal plates superposed on each other a main channel defined by a first inflated portion of large cross section, and at least one branch channel defined by a second inflated portion communicating with the main channel and having a small cross section. The device comprises a single component provided by two metal plates, and is simple in construction and reduced in the number of parts, manufacturing cost and weight. The device is produced by roll-bonding two metal plates, forming at least one second inflated portion having a small cross section and defining the branch channel by primary inflation with a low fluid pressure, thereafter holding the two metal plates with dies, and forming a first inflated portion having a large cross section and defining the main channel by secondary inflation with a high fluid pressure.