SAE International Physically Motivated Model for Efficient Dynamic Simulation of Chain Tensioners with Labyrinth Seals 2017-01-1073

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. Therefore, a third approach for modeling a labyrinth sealing is derived. Using dimensional analysis the labyrinth can be described by a non-dimensional equation. Only a few coefficients have to be determined by measurements. Hence, the effort for parameter identification as well as the number of necessary experiments is significantly reduced. All three approaches are validated with experimental data. Next, a dynamic model of a complete chain tensioner including labyrinth seals was built up. A comparison between simulation and measured data of the flow characteristics as well as of the dynamic behavior is presented to prove accuracy, benefits and practicability of the presented approach. Furthermore, the influence of fluid inertia in the hydraulic lines is analyzed.