Variable Induction Control Valve: Description and Operation

Variable Resonance Induction System (VRIS):

PURPOSE
The Variable Resonance Induction System (VRIS) improves low speed torque through the engine speed controlled resonance charge effect.

OPERATION
The system takes advantage of high and low pressure oscillations in the intake manifold created by the opening and closing of the intake valves. As one intake valve closes, air compresses behind the valve. When the air rebounds, a pressure wave travels through the intake manifold, forcing air to fill other cylinders. The engine speed at which this is effective is varied by changing the effective volume of the manifold and the length of the passage between the cylinders. To do this, the shutter valve is opened and closed at different engine speeds.

Two shutter valves and actuators, located on the dynamic chamber, are controlled by the ECU via vacuum solenoid valves. To improve torque at low and mid-range rpm, two passages between the manifold halves are opened. The two halves of the manifold are joined, increasing the effective volume of the manifold to provide improved cylinder charging. At high engine speeds, the shutter valves are closed, shortening intake runner length and reducing effective volume of each half to improve high rpm performance.