Simulation of air pressure control valves for crankcases

Publisher Summary This chapter develops a simulation model to simulate the dynamic behavior of pressure control valves, which are used in combustion engines to prevent overpressure in the crankcase resulting from the blow by gases. The chapter also presents a system model consisting of valve, crankcase, and intake manifold that are interconnected. Because of the oil sump in the crankcase, two phases of the fluid must be regarded—consisting of exhaust gas and oil vapor as well as oil liquid. There are several models to describe compressible twophase flows. To calculate the critical two-phase flow rates, the Moody model can be applied. This model assumes thermodynamic and fluid dynamic equilibrium and isentropic flow of the mixture. The flow rates have to be calculated iteratively. The chapter compares the simulation results with the measurements of a BMW four-cylinder engine after presenting the system model.