Variable valve control device, variable valve control system, and method for controlling variable valve mechanism

A variable valve control device applied to an internal combustion engine provided with a variable valve mechanism capable of varying a rotation phase of a camshaft with respect to a crankshaft by a rotation of a motor, and configured to control the motor based on a target value of the rotation phase, the variable valve control device comprising:

• a motor angle signal acquisition part configured to acquire, as an input, a motor angle signal, which is an output signal from a motor angle sensor configured to detect an angle of rotation of the motor;
• a crank angle signal acquisition part configured to acquire, as an input, a crank angle signal, which is an output signal from a crank angle sensor configured to detect an angular position of the crankshaft;
• a communication part connected to an in-vehicle communication network and configured to acquire control information including a first detection value, which is a detection value of the rotation phase based on a detection signal of the angular position of the crankshaft and a detection signal of an angular position of the camshaft, and the target value, via the in-vehicle communication network;
• a second detection value computing part configured to compute a second detection value, which is a detection value of the rotation phase, by computing an amount of variation in rotation phase per computation cycle based on a rotational speed of the motor computed based on the motor angle signal and a rotational speed of the crankshaft computed based on the crank angle signal and integrating the amount of variation;
• a determination part configured to determine whether a rotation phase control for making the rotation phase approach the target value is in a transient state or in a steady state;
• a switching part configured to switch a detection value of the rotation phase used for controlling the motor to the second detection value when the rotation phase control is in the transient state and switch the detection value of the rotation phase used for controlling the motor to the first detection value when the rotation phase control is in the steady state;
• and
• a control part configured to control the motor based on the target value and the detection value of the rotation phase switched by the switching part.