ABSTRACT
Using the concept of the layered cylinder head of the Changan new-generation engine, this paper first details a series of NVH analyses and the results are assessed based on the CA in-house dynamic response database and the data from three benchmark engines. In terms of NVH performance, the beneficial features have also been summarized after comparing the benchmark heads focusing on structural characteristics, such as the global architecture, oil gallery layout, layout for the reinforcements (ribs), camshaft carrier, and camshaft caps. In order to reach the CA NVH targets, such as modal, dynamic stiffness, and sound power radiation, the improvement recommenda-
1 INTRODUCTION
It is well known that the cylinder head is one of the most essential engine components, its structure directly or indirectly affects the NVH performances of the head itself and the whole Power Train (PT), because it is the main path from the excitation (gas force and forces from valve train) to main structure-borne noise contributors, such as cam cover, intake manifold, exhaust manifold, and timing cover. The introduction of the environmental legislations, the demand for fuel economy, and the public environmental awareness results in the wide incorporation of Variable Valve Lift (VVL) technology, for which the structure of the two-layered cylinder head is favorably developed. However, this kind of structure not only makes the design optimization more difficult but also directly affects the overall stiffness of the engine causing the NVH performance concerns.
