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The object of this study is a new chain tensioner with two labyrinth seals. For the simulation of chain tensioners within the framework of multi-body dynamics, a physically orientated model to describe the fluid dynamics of the labyrinth seals is derived. The easiest way to describe labyrinth seals is to use maps obtained from measurements. As this is very time-consuming, methods of 1D and 2D fluid-mechanics are used in this work to model the labyrinth seals. The seals are characterized by physically motivated parameters e.g. coefficients of resistance or friction. As these parameters can be derived from geometric data, a very good forecast feasibility without experimental investigations is provided. For high accuracy simulations model parameters can be refined by experimental data. As many and highly complex parameters have to be identified, this refinement is very time-consuming and requires lots of experiments.

In this paper, a spring model based on a curved beam is used for the simulation of cylindrical, conical and beehive valve springs. The internal dynamic are described by hyperbolic partial differential equations which are discretized by the finite element method. The contacts between adjacent windings are included using the Augmented Lagrangian method and non-smooth contact mechanics. For smooth contact modeling, spring and damper elements are used to minimize penetration of the bodies coming into contact. Rigid or non-smooth contact forces are subject to set-valued force laws describing the condition of non-penetration. Both contact models are compared. The derived spring models for all three types of winding shapes are validated in the frequency and time domain with experimental data. In the second part, a multi-body simulation model of an entire valve train including the derived spring model is presented.

The valve train plays a huge role in the performance of internal combustion engines by controlling the combustion process and is therefore one starting point to increase the efficiency of combustion engines. Considering the dynamics, the valve spring is the component with the lowest natural frequency in the motor and therefore plays a crucial role in the overall dynamics of the valve train. The spring force must be high enough to close the valve reliably and prevent the valves from bouncing of the seating due to surge modes after they have closed. Conversely, the spring force affect the friction level in the engine and therefore fuel consumption. For this reason the spring forces should be kept as low as possible. Modelling valve springs it has to be taken into account, that the dynamic response of the spring is substantially different from the static response.

Fully variable valve trains provide comprehensive means of adjustment in terms of variable valve timing and valve lift. The efficiency of the engine is improved in the operating range and in return, an increasing complexness of the mechanical design and control engineering must be handled. For optimization and design of these kinds of complex systems, detailed simulation models covering different physical domains, i.e. mechanics, hydraulics, electrodynamics and control are needed. Topic of this work is the variable valve train named Audi valvelift system (AVS) e.g. used in the Audi 2.8l V6 FSI engine. The idea of AVS is to use different cam lobes at different operating points. Each intake valve can be actuated by a large and a small cam. For full load, the two inlet valves are opened by the large cam profile - ideal for high charge volumes and flow speeds in the combustion chamber. Under partial load, the small cam profiles are used.

Nowadays, multi-body systems theory including bilateral and unilateral constraints is comparatively well established by means of set-valued force laws. Although methods of non-smooth mechanics enable a highly efficient modeling, they are not conventionally used in industrial practice. Therefore in the present paper a valve train including hydraulic elements like a hydraulic lash adjuster is modeled using above mentioned methods. A main focus is laid upon the treatment of contact problems and two different models are investigated. Contacts in multi-body dynamics are classically described using spring and damper elements minimizing penetration. This approach results in stiff differential equations with unintentional high eigenfrequencies and long computing times as well as uncertainties in the parameters for contact stiffness and damping. Whereas in rigid contact models the contact is supposed to be completely stiff leading to non-smooth systems.