Patent ID: 6691021
Filing Date: 2004-02-10
Classification: F01L,F02D

Abstract:
A failure determination system for a variable-cylinder internal combustion engine including a plurality of cylinders each having at least one intake valve and at least one exhaust valve, and a valve-actuating system including a valve-actuating mechanism for actuating said at least one intake valve and said at least one exhaust valve of each of said cylinders, said engine being capable of switching a cylinder operation mode between an all-cylinder operation mode in which all of said plurality of cylinders are operated, and a partial-cylinder operation mode in which fuel supply to part of said plurality of cylinders is stopped and at the same time said part of said plurality of cylinders are made idle by stopping said valve-actuating mechanism from actuating said at least one intake valve and said at least one exhaust valve of each of said part of said cylinders,the failure determination system comprising: oxygen concentration-detecting means for detecting a concentration of oxygen in exhaust gases exhausted from said plurality of cylinders; failure-determining operation mode-executing means for executing a failure-determining operation mode for causing said valve-actuating mechanism to resume actuation of said at least one intake valve and said at least one exhaust valve of at least one of said part of said cylinders in a state in which said fuel supply to said part of said cylinders is stopped, when said cylinder operation mode is switched from said partial-cylinder operation mode to said all-cylinder operation mode; and failure determination means for determining whether or not said valve-actuating system including said valve-actuating mechanism has failed, based on an oxygen concentration detected by said oxygen concentration-detecting means when said failure-determining operation mode is executed.