| 摘要 |
<p>PURPOSE:To prevent a failure to ignite fine particles contained in the exhaust gas, owing to high flowing velocity of exhaust gas, by providing a bypass pipe, having an open/close valve, and bypassing a trap device for exhaust fine particles, to a main outlet pipe, and by flowing exhaust gas, also through the bypass pipe, only when the exhaust fine particles are ignited in the trap device. CONSTITUTION:A trap 12 is provide to a main outlet pipe 5 which is positioned on the after flow side of an exhaust mainfold 9 for an engine body 1. It is composed of a trap material 20 to catch exhaust fine particles and an electric heater 16 to burn them. In this case, a bypass pipe 6 to connect the upstream side of a trap 12 to the downstream side of it is provided to the main outlet pipe 5, and a control valve 31 of normally closed type, to open the pipe 5 at the specified condition, is provided to the inside of a bypass pipe 6. Most of the exhaust gas is flowed passing through the bypass pipe 6, only when the exhaust fine particles are ignited by the heater 16, by opening the normally closed control valve 31, by changing the negative pressure changing valve 35 in a diaphragm device 33 by the command of a CPU. By this method, an ignition failure for the exhaust fine particles, caused by high flowing velocity of exhaust gas, can be prevented.</p> |
