Patent ID: 9458776
Filing Date: 2016-10-04
CPC Classification: F02D,G01M,Y02T

Claim Text:
1. An abnormality diagnosis device of a variable valve mechanism that is configured to be capable of selecting a first mode, which opens an exhaust valve only during an exhaust stroke or a second mode, which opens the exhaust valve during the exhaust stroke and also during an intake stroke, comprising: an intake air amount detection device for detecting an intake air amount flowing in an intake passage; an exhaust gas pressure detection device for detecting a pressure of an exhaust gas; an exhaust gas returning amount calculation device for calculating an exhaust gas returning amount that is recirculating into a cylinder from an exhaust passage in the second mode based on an intake air amount in the first mode detected by the intake air amount detection device and an intake air amount in the second mode when a predetermined diagnosis condition is satisfied; an exhaust gas returning amount estimation device for estimating an exhaust gas returning amount that is recirculating into the cylinder from the exhaust passage in the second mode based on the exhaust gas pressure detected by the exhaust gas pressure detection device when the predetermined diagnosis condition is satisfied; and an abnormality determination device for determining that the variable valve mechanism is abnormal when a difference between an exhaust gas returning amount calculated by the exhaust gas returning amount calculation device and an exhaust gas returning amount estimated by the exhaust gas returning amount estimation device is bigger than a diagnosis threshold value; wherein the exhaust gas returning amount estimation device estimates that the higher the exhaust gas pressure detected by the exhaust gas pressure detection device is, the larger the exhaust gas returning amount is.