This content is not included in your SAE MOBILUS subscription, or you are not logged in.
Transient thermal behavior of dry clutch under non-uniform pressure condition
ISSN: 0148-7191, e-ISSN: 2688-3627
To be published on April 14, 2020 by SAE International in United States
Accuracy of thermal models is critical to clutch design in case of excessive temperatures due to large amounts of friction heat generated in the narrow space. Pressure distribution on the clutch friction interface is an important factor affecting heat flux distribution, thus affecting temperature distribution. But no previous literature reported how the pressure is distributed on dry clutches. This study conducts an experiment to obtain the pressure distribution for one typical dry clutch equipped with a set of diaphragm spring. Considering that the frictional interface is in contact, ordinary pressure sensors are not applicable because they have to separate the interface for a certain distance. Addressing this difficulty, this study makes use of pressure sensitive film and acquires data based on image processing techniques. Thereafter, a polynomial model with dimensionless parameters is developed to fit the pressure distribution. Thus, the non-uniform pressure model is worked out. After that, the proposed pressure model is applied to a thermal model based on finite element method. In addition, two conventional thermal models, which use uniform pressure and uniform heat flux assumptions respectively, are implemented for comparison. The heat-flux generated by the non-uniform pressure model reaches the maximum at a distance from the outer circumference, but that by the uniform pressure reaches the maximum at the outer circumference, that by the uniform heat flux keeps unchanged from inner to outer circumference. The simulation results of the three thermal models are provided with temperature profiles along with time and radius. The results from the non-uniform pressure model agrees the experimental results better than those from the two conventional models. Therefore, the proposed non-uniform pressure model is validated to improve the accuracy of the thermal model for dry clutches.