Search Results

The use of hydroforming technique is commonly used for the manufacturing of BIW, chassis and suspension components. For low weight and cost effective solutions it is also finding application in powertrain components mainly in the engine camshafts. Weight of the valvetrain parts plays a vital role for enhancing the engine response and performance. Hollow camshafts are produced by assembling aggregate parts, i.e., cam lobes, journals, sprockets etc. on a tubular shaft. Compared to conventional solid cast or forge camshafts, hollow camshafts provide opportunities for weight reduction exceeding 60%, design flexibility to improve performance of engine and valve train because of reduced rotational inertia. In order to obtain the above benefits the valve train of an existing 4-cylinder 4-stroke diesel engine is modified by replacing the solid forged camshaft with a hollow camshaft. The main consideration in carrying out the change is that the valve train performance should be enhanced.

The major area in which the automotive manufacturers are working is to produce high-performance vehicles with lighter weight, higher fuel economy and lower emissions. In this regard, hollow camshafts are widely used in modern diesel and gasoline engines due to their inherent advantages of less rotational inertia, less friction, less weight and better design flexibility. However, the dynamic loads of chain system, valve train and fuel injection pump (if applicable) makes it challenging to design over-head hollow camshafts with the required factor of safety (FOS). In the present work, high-fidelity FE model of a hollow camshaft assembly is simulated to evaluate the structural performance for assembly loads, valve train operating loads, fuel injection pump loads and chain system loads. The investigation is carried out in a high power-density (70 kW/lit) 4-cylinder in-line diesel engine.