| 摘要 |
<p>PURPOSE:To prevent choking of a purifying device by arranging a purifying device and an exhaust gas throttle valve in an exhaust gas passage and providing a detecting device to detect the choking state of the purifying device and a control device to open the exhaust gas throttle valve after the valve is closed during a time for which rotation is effected at the given number of revolutions high enough to allow the increase of an exhaust pressure. CONSTITUTION:When an engine 1 is run, exhaust gas flows through an exhaust gas passage 3 to a catalyst 4 and after it is purified, it is discharged in the open air. A control unit 6 inputs signals from a first pressure sensor 7, a second pressure sensor 8, a number of revolutions detecting device 9, and a load detecting device 10, compares a normal differential pressure given value when it is equivalent to the actual measurement number of revolutions of an engine and a load with an actual measurement differential pressure, and decides chocking of the catalyst 4. When choking occurs, a command is given to an actuator 11, and an exhaust gas throttle valve 5 is closed. When the exhaust gas throttle valve 5 is opened after a lapse of a given time, exhaust gas generates forced blow, and carbon which is about to be stuck to the catalyst 4 or with which the catalyst is about to be choked is removed at once so as to prevent the occurrence of choking.</p> |
