LEAKAGE DIAGNOSIS METHOD AND LEAKAGE DIAGNOSIS DEVICE FOR BLOW-BY GAS TREATMENT DEVICE OF INTERNAL COMBUSTION ENGINE

摘要

A blow-by gas treatment device is provided with: a pressure control valve (18); a fresh air introduction pipe (21); a blow-by gas first pipe (22); a blow-by gas second pipe (23); a shut-off valve (24); a one-way valve (25); and a PCV valve (26). A leakage diagnosis A includes a first stage diagnosis for determining whether or not a pressure reduction in a crankcase (3) after closing of the shut-off valve (24) under a non-supercharging condition is normal, and a second stage diagnosis carried out under the non-supercharging condition when the first stage diagnosis indicates that there is an anomaly. In the second stage diagnosis, the pressure control valve (18) is moved from fully-opened to fully-closed, and it is determined whether the air intake amounts are equal between the states. When the air intake amounts are equal, leakage within a system is determined to have occurred. When the air intake amount at the fully-closed time is different from that at the fully-opened time, leakage to the outside of the system is determined to have occurred.