In engines destined for use in Mercedes-Benz passenger cars, the phasing of the camshafts is regulated with hydraulic cam phasers. New engine applications in conjunction with higher expectations relating to the performance of the adjustment increasingly require the optimization of the oil circulation in the system.
The cam phasers currently used work on the swivel-vane/swivel-motor principle. The system to be simulated includes the oil circulation in the camshaft bearings, the central valve integrated in the adjuster and the adjuster with hydraulic lock. The tasks to be resolved in order to model the adjuster are characterized in particular by the highly variable chamber volumes in conjunction with the movement controlled by the fluid. Another task was to integrate the central valve into the simulation as a component of the system.
The modeling of the phaser in STAR-CCM+ is based on parameterized CAD models in "3-D-CAD Modeler". Because of the complex inflow and outflow geometry, particular attention was paid to the definition of the interfaces. The movement of the swivel vane adjuster is modeled using 6-DOF morphing. The severe deformation of the mesh within the adjuster chambers demands re-meshing, depending on the current mesh quality. The look-pin movement is modelled with a Overlapping/Overset Mesh.
The simulation model presented allows the influence of the component design on the target variable – the rate of adjustment in the system environment – to be evaluated. A tool for calculating and visualizing the camshaft adjuster system has thus been introduced to the digital development process.