Patent ID: 8919306
Filing Date: 2014-12-30
Classification: F01L

Abstract:
1. A controller for a variable valve device of an internal combustion engine, the variable valve device including a phase changing mechanism of a hydraulic type that changes valve timing, and a phase locking mechanism that locks the valve timing to a predetermined specific phase, comprising: a limiting control unit configured to execute a limiting control that limits an operation of the phase changing mechanism, wherein an operational state of the phase changing mechanism in which the valve timing is locked to the predetermined specific phase is defined as a phase-locked state, the predetermined specific phase is a phase between a most retarded phase and a most advanced phase; an operational state of the phase changing mechanism in which the valve timing can be changed is defined as a phase-unlocked state; a range defined by two different phases and over which the valve timing can be changed when the phase changing mechanism is in the phase-unlocked state is defined as a variable range; a temperature of a hydraulic oil in the phase changing mechanism is defined as an oil temperature; a viscosity of the hydraulic oil in the phase changing mechanism is defined as an oil viscosity; a state in which the oil temperature is within a predetermined temperature range is defined as a predetermined oil temperature state; a predetermined phase located on a retard side with respect to the predetermined specific phase within a range from the most retarded phase to the predetermined specific phase is defined as a retard-side limit phase; a range from the predetermined specific phase to the retard-side limit phase is defined as a retard-side limit range, the retard-side limit range is included in the variable range; and in the limiting control, the limiting control unit sets the retard-side limit range in the predetermined oil temperature state, when the oil viscosity is high, to a size smaller than a size of the retard-side limit range in the predetermined oil temperature state, when the oil viscosity is low.