VTEC/VTC System Description - Construction
The VTEC mounted in this engine has a mechanism obtained by combining a variable valve lift mechanism VTEC and a variable valve timing mechanism VTC. This is for the purpose of improving the output and fuel consumption and lowering the exhaust gas level.
VTEC Camshaft
The intake camshaft is structured so that each cylinder has two short duration cam lobes for Otto cycle and a wide duration cam lobe for Atkinson cycle.
VTEC Rocker Arm
The intake rocker arm is composed of the primary, the mid, and the secondary rocker arms. The inner side of the primary rocker arm has a stopper piston and a return spring. The inner side of the mid and the secondary rocker arm have a VTEC switching piston in each rocker arm.
Rocker Arm Oil Control Valve
The rocker arm oil control solenoid in the rocker arm oil control valve assembly turns ON or OFF the solenoid depending on a signal from the PCM to switch the hydraulic pressure applied to the valve. By switching the spool valve ON/OFF, the hydraulic pressure applied to the VTEC piston in the rocker arm is controlled.
Electrical VTC
The electrical VTC is adjusted through electric control, this enables the phase of the intake camshaft to have non-step advances or retards the valve timing.
The VTC consists of the electric VTC motor, which is integrated with the control unit, and the VTC actuator. The electric VTC motor drives the VTC actuator, and advances or retards the valve timing by changing the phase.
The VTC motor is controlled through commands from the PCM. The PCM advances or retards the valve timing based on the data from various sensors, and performs feedback-control based on the data from the CMP sensor.