The four-stroke internal combustion engine is a wide spread concept applied in nearly every passenger car. The control of the intake and exhaust valves in the individual cylinders plays a crucial role in the performance of the engine. Therefore, there is a great demand to optimize the cam design with respect to different criteria. As an example, a valve should open wide and for as long as possible in order to facilitate flow of the air-fuel mixture and exhaust gases in and out of the cylinders. On the other hand, contact forces should be kept low, because they result in energy loss due to friction and therefore in higher fuel consumption or less engine power respectively. Prior investigations have presented the use of optimal control theory in the design of high-speed cam follower systems. These investigations were constrained by the difficulty of numerical solutions of optimal control problems, and this limited the types of criteria investigated, the state inequality constraints considered, and the realism of the models used. In recent years numerical solution techniques based on direct multiple shooting and using specially structured sequential quadratic programming have become available. This paper investigates and illustrates the potential of such methods in revolutionizing high speed automotive cam design. Cam design is complicated by the number of partially competing criteria one is interested in. This work synthesizes an optimal cam design approach, considering a range of speeds, the area under the lift curve, Hertzian contact stress, vibrations and residual vibrations, energy loss, cam curvature, follower force, and contact stress. The paper illustrates how all of these criteria can be integrated into the optimization in the design stage. Since the polydyne method is not an optimization procedure, the resulting design is superior to polydyne design in all aspects considered.


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    Title :

    High speed automotive cam design using direct multiple-shooting optimal control techniques


    Additional title:

    Entwurf eines Hochgeschwindigkeits-Fahrzeugnockens unter Einsatz direkter Multiple-Shooting-Optimalregelungsmethoden


    Contributors:


    Publication date :

    2004


    Size :

    22 Seiten, 22 Bilder, 1 Tabelle, 20 Quellen



    Type of media :

    Conference paper


    Type of material :

    Print


    Language :

    English




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