Variable Induction System: Description and Operation

Variable Resonance Induction System (VRIS):

To improve low speed torque, the Variable Resonance Induction System (VRIS) take advantage of the resonance charge effect by means of a shutter valve, actuator and ECU controlled solenoid valve. The system also uses a check valve and vacuum chamber to prevent erratic operation under heavy load conditions.

The shutter valve is located in the dynamic chamber and moved by a vacuum actuator. Depending on operating conditions, the ECU energizes the solenoid valve to apply or cut off vacuum to the actuator, making optimum use of the resonance charge effect. It is the shutter valve that effectively changes resonance pipe length, making the system variable.

Engine speed at which this is effective is determined by dynamic chamber capacity and length of the passage between cylinders.

Resonance charge uses intake air pressure waves caused by the closing or opening of intake valves. As each cylinder's intake valve opens or closes, it forces air to fill other cylinders.