Variable valve train control device

A variable valve train control device comprising:

• a variable valve train which uses a hydraulic actuator to vary a valve opening characteristic of an intake valve or an exhaust valve of an internal combustion engine;
• an oil temperature acquisition device for detecting or estimating an oil temperature;
• a hydraulic control valve for controlling oil pressure acting on the hydraulic actuator in accordance with a duty value of a control signal;
• a first feedback control device for exercising duty value feedback control to calculate a duty value in accordance with a deviation between an actual valve opening characteristic and a target valve opening characteristic;
• a second control device which, when predefined second control execution conditions are established, exercises second control instead of the duty value feedback control to vary the duty value in a pulsed manner between a retention duty value, which retains an operation of the hydraulic actuator, and a forced drive duty value, which forcibly drives the hydraulic actuator,
• an initial pulse extension device which, when the oil temperature is lower than a predetermined temperature, ensures that the initial pulse width generated after the start of the second control is wider than normal;
• an initial response lag acquisition device for acquiring a response lag between the instant at which the initial pulse of the second control rises and the instant at which the hydraulic actuator starts operating;
• and
• an initial pulse width correction device which, when the response lag is shorter than a predetermined period of time, shortens the initial pulse that is set by the initial pulse extension device.