US Patent 7458347 Apparatus and method for controlling variable valve operating mechanism

In an internal combustion engine equipped with a variable valve operating mechanism that performs a valve timing control and a valve lift amount control of at least one of an intake valve and an exhaust valve, target values of the valve timing and the valve lift amount set based on an engine operating condition are limited by a limit value to limit a control range of one of the valve timing and the valve lift amount in accordance with a control state of the other of the valve timing and the valve lift amount, so that the valve timing and the valve lift amount are controlled based on the respective target values one of which has been limited as above.