Cartwaveforms > actuators > purge valve > Carbon Canister Solenoid Valve (Purge Valve)
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Carbon Canister Solenoid Valve (Purge Valve) Waveform Notes
This canister contains active charcoal or active carbon granules. Most evaporation control systems reduce the emission of fuel vapour during the time the vehicle is idling in traffic, or parked in strong sunshine by absorbing the vapour fumes into the carbon canister. Once the engine is at its normal operating temperature the stored hydrocarbons are released into the inlet manifold where they become part of the combustible air/fuel mixture.
The control for allowing the hydrocarbons to be released into the inlet manifold through a cut off valve, can be achieved electrically or by vacuum: the operating principal is the same for both, our example is from the electronic solenoid type.
The electronic solenoid is controlled by the Electronic Control Module (ECM) by switching the earth path to ground under specified conditions. The purge valve/carbon canister has a 12 volt supply and its switching can be seen in the example waveform.
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