Improvement of the internal combustion engine cam-tappet pair characteristics using numerical step-by-step cam design method

In this paper the numerical step-by-step method of cam profile design is presented. The results of its using for internal combustion engine valve gear are submitted. Its basis is a principle of step-by-step formation of the tappet movement law taking into account restrictions, which permit to refuse of before hand, accepted cam profile description. Thus instead of the analytical law of tappet movement the numerical representation is used, and the algorithm of positive and negative acceleration forming provides maximum cam efficiency, depending on the tappet displacement diagram completeness and connected to it valve timing. A longside with formation of the tappet movement law definition of the necessary data for manufacturing and the control of the corresponding cam profile using various kinematic schemes is stipulated. This method allows to profile of maximum efficiency cams in view of many restrictions on parameters, connected to valve gear serviceability and reliability: contact stress in cam-tappet pair, pressure angle, coverage factor of the valve springs effort, radius of cam profile curvature, oil film thickness in the cam-tappet pair and the restrictions on the higher order of derivative from the tappet displacement on the cam turn angle. Efficiency ofa considered method has been confirmed at profiling cams for lines of tractor and automobile engines