Thermal behavior of a double cone synchronizer with carbon friction lining – verification and validation of 2D thermo-mechanical simulations by temperature measurements

Synchronizers are important machine elements in gearboxes used in cars and trucks. A continuous demand for higher power density in transmissions increases the load requirements on these components. Modern Carbon friction linings can significantly improve the performance of synchronizers, but the low thermal conductivity of these materials results in high friction surface temperatures that can both damage the friction lining and lubricant. Using double cone synchronizers can further increase the power density, but the thermal loads as well. Understanding the thermal behavior of a synchronizer is important in order to improve its performance. This paper presents a 2D thermo-mechanical FEM model to calculate the temperature distribution in a double cone synchronizer. Extensive temperature measurements verify and validate the model. Practical guidelines for measuring temperatures in synchronizers are provided. The simulated temperatures correlate well with the measurements. Several parameters that influence the maximum temperature are analyzed, such as load parameters, different simulation approaches, position of temperature sensors, sensor time delay, and the influence of material properties. Measurements in combination with simulations demonstrate that cooling during the engagements and the friction of sliding blocks influence the temperature increase during an engagement.