VALVE CHARACTERISTIC CONTROL DEVICE AND VARIABLE VALVE OVERLAP MECHANISM FOR INTERNAL COMBUSTION ENGINE

摘要

PROBLEM TO BE SOLVED: To prevent cold time hesitation by suppressing thinning of an air-fuel ratio without depending on increased fuel quantity in a cold time idle state. SOLUTION: By constituting the device and mechanism by a helical spline of a rotation phase difference variable actuator, a cam profile of an intake cam and a lift variable actuator, the device and mechanism become automatic for valve timing (Ls=0 shown in figure) for realizing valve overlapθov for cold time at the non-driving time of each actuator. By an exhaust blow back phenomenon by the valve overlapθov for cold time, vaporization of fuel within a combustion chamber and an intake port is promoted. Therefore, air-fuel mixture becomes a sufficient air-fuel ratio without depending on increased fuel quantity in the cold time idle state, combustion becomes more stable than a case in which valve overlap is not increased, cold time hesitation is prevented and drivability can be maintained in a comparatively excellent state.