Exhaust gas purification system of internal combustion engine

摘要

In an internal combustion engine (1), an exhaust purification system includes an exhaust purification means (17); an exhaust throttle valve (10), provided downstream of the exhaust purification means (17); and determination means (16) for determining whether or not the exhaust purification means (17) has broken. If the determination means (16) determines that the exhaust purification means (17) is broken, the opening degree of the exhaust throttle valve (10) is increased or fully opened. Therefore, even if pieces of the broken exhaust purification means (17) flow down the exhaust passageway (9), the broken pieces pass through the exhaust throttle valve (10) without accumulating there. Thus, the blockage of the exhaust passageway (9) by such broken pieces is reduced.