EVAPORATIVE EMISSION CONTROL SYSTEM





HC (hydrocarbon) generated in the fuel tank are adsorbed by the active carbon in the canister and stored. HC stored in the canister is introduced to the inlet manifold when engine is in operation where it is mixed with intake air and combusted. Engine-ECU introduces optimum HC amount according to driving conditions and so performs duty control on the purge control solenoid valve. Also, the purge control solenoid valve is closed during deceleration or immediately after engine start to restrict change in air-fuel ratio and prevent engine from stalling.

PURGE CONTROL SOLENOID VALVE



A purge control solenoid valve is installed in the inlet manifold. The purge control solenoid valve controls the intake volume of fuel vapour gas from the canister. The purge control solenoid valve is a duty control type solenoid valve. When current is not passing through the coil, nipple A is kept airtight and fuel vapour gas cannot be sucked in. When current passes through the coil, air can pass between nipple A and B and fuel vapour gas is sucked in. Engine-ECU changes the ON duty ratio according to engine’s operating condition to control the intake volume of fuel vapour gas.