| 摘要 |
<p>PURPOSE:To obtain trap-melting-damage preventing function without impairing fluidity of an exhaust gas by providing both a first bypass pipe, which bypasses a particulate trap installed an exhaust pipe, and a second bypass pipe, which leads the exhaust gas flowing backward in the trap to an exhaust pipe on the downstream side of the trap. CONSTITUTION:An exhaust pipe 10 is provided with a trap container 16 containing both a particulate trap 12 and an electric heater 14 which is used for regeneration of this trap 12. A branch part 20, which is situated more upstream side than the trap 12 of the exhaust pipe 10, and a confluence part 22, which is situated more downstream side than an electric heater 14, are connected by a first bypass pipe 18, and first and second opening/closing valves 24 and 26 are provided at the downstream position of the branch part 20 at the confluence part 22 of the exhaust pipe 10, respectively. In addition, a second bypass pipe 28, which connects a spot between the first opening/ closing valve 24 and the trap 12 to the confluence part 22, is provided, and a third opening/closing valve is installed in the midst of the second bypass pipe 28. With this contrivance, the exhaust gas, which comes through the first bypass pipe 18, can be introduced all to the downstream side without being introduced into the trap 12.</p> |
