CRANK CASE EMISSION CONTROL

The basic principle of a crank case blow-by control system is the recirculation of vapours back to the inlet manifold. Figure 11.24 shows a typical closed type known as a positive crank case ventilation (PCV) system. The gases escaping past the piston and entering into the crankcase are returned to the inlet manifold and then to the engine. During compression, the HC enters into the crankcase due to pressure difference between the engine cylinder and crank case (small vacuum) and the HC from the crank case is taken back into the intake manifold during the expansion stroke and back side of the piston compresses the gases in the crank cases.