Variable performance valve train having three-dimensional cam

A valve train for an internal combustion engine, comprising:

• a variable ye performance mechanism including a three-dimensional cam having a profile that continuously changes in the axial direction, the variable valve performance mechanism continuously changing the valve open angle of an intake valve;
• a controller for controlling the variable valve performance mechanism;
• a sensor for detecting the running state of the engine;
• and
• a judging device for judging whether there is a malfunction in the engine based on a detection signal of the sensor, wherein, when the judging device judges that there is a malfunction in the engine, the controller actuates the variable valve performance mechanism to advance the closing timing of the intake valve.

A method for changing the valve performance of at least one of an exhaust valve and an intake valve by using a three-dimensional cam, the method comprising:

• detecting the running state of an engine;
• judging whether the engine is running normally based on the detected running state;
• controlling a valve open angle based on the detected running state when the engine is judged to be running normally;
• and
• decreasing valve overlap when the engine is judged to be running abnormally, wherein the profile of the three-dimensional cam continuously changes in the axial direction.

A method for changing the valve performance of an intake valve by using a three-dimensional cam, the method comprising:

• detecting the running state of an engine;
• judging whether the engine is running normally based on the detected running state;
• controlling a valve open angle based on the detected running state when the engine is judged to be running normally;
• and
• advancing the closing timing of the intake valve for performing a failsafe when the engine is judged to be running abnormally, wherein
• the profile of the three-dimensional cam continuously changes in the axial direction.