Patent ID: 7500363

Claim:
A failure detecting device for supercharging-pressure control means in a supercharging device of an engine, the supercharging device comprising: a turbocharger for supercharging the engine; supercharging-pressure control means for controlling a supercharging pressure in a supercharging intake air passage downstream of the turbocharger; engine-load detecting means for detecting an engine load; and supercharging-pressure detecting means for detecting the supercharging pressure in the supercharging intake air passage, wherein the failure detecting device comprises: acceleration-state determining means for determining whether a turbine is in an acceleration state on the basis of the engine load detected by the engine-load detecting means; supercharging-pressure-control-state determining means for determining whether the supercharging-pressure control means is in a maximum supercharging pressure control state for maximizing the supercharging pressure in the supercharging intake air passage; failure-detection permitting means for permitting failure detection for the supercharging-pressure control means, when the engine-load detecting means detects an engine load equal to or larger than a predetermined value, the acceleration-state determining means determines that the turbine is in the acceleration state, and the supercharging-pressure-control-state determining means determines that the supercharging-pressure control means is in the maximum supercharging pressure control state; convergent-value calculating means for calculating a convergent value of the supercharging pressure on the basis of the engine load detected by the engine-load detecting means, when the failure-detection permitting means permits the failure detection; delay-coefficient calculating means for calculating a delay coefficient of the turbocharger on the basis of the supercharging pressure detected by the supercharging-pressure detecting means and the convergent value of the supercharging pressure calculated by the convergent-value calculating means; and failure determining means for determining whether a failure of the supercharging-pressure control means has occurred on the basis of the delay coefficient calculated by the delay-coefficient calculating means.