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Brake squeal has been found to be related to varying temperatures. In order to investigate this problem, the finite element method is applied to a disc brake system. Thermal analysis is incorporated to assist complex eigenvalue analysis to extract unstable modes which may contribute to squealing phenomena over a series of discrete temperatures. The SAE J2521 test sequence is simulated to predict the temperature variations on the whole three dimensional geometry of the brake pads and the disc, during the prescribed drag braking situations. This coupled thermal structural analysis considers different stages of the drag brake event, particularly the difference in the temperature distribution and consequent contact status during the heating and cooling stages. The coupled analysis leads to the prediction of squealing instability measures and frequency spectra.

This paper proposes an approach to optimize the economy performance of a two-speed electric vehicle (EV) by combining gear shifting schedule design and gear ratios selection. Mathematic models for the two-speed EV subsystems are developed, including those of the battery module, electric machine, the driver, transmission and vehicle. Then a procedure for obtaining the optimal gear ratio pairs and corresponding shift schedule for the two-speed EV is presented in detail. The optimized EV powertrain parameters can not only ensure that basic requirements in dynamic performance are achieved, but realize the optimal economic performance of the EV as well. In order to investigate the effectiveness of the proposed method for EV design, simulations based on the developed powertrain model is conducted using different test driving cycles, including NEDC and constant speed. Results of these simulations validate the effectiveness of the proposed optimization method.

This paper mainly studies the power losses in a refined two-speed dual clutch transmission which is equipped in a electric vehicle test rig. Both numerical and experimental investigations are carried out. After theoretical analysis of the power losses original sources, the developed model is implemented into simulation code to predict the power losses. In order to validate the effectiveness of the proposed model, results from experimental test are used to compare the difference the simulation and test. The simulation and test result agree well with each other. Results show that the power losses in the two-speed are mainly generated by multi-plate wet clutch drag torque and gear churning loss.

Method to improve the efficiency and the design of more efficient pure electric vehicle (PEV) system is a research hotspot for the automobile industry worldwide. Traditionally, PEV powertrains are dominated almost exclusively by single reducer structures in both concept and commercially available PEVs. This paper presents a novel two motor two speed pure electric power-train structure to study alternate methods for improving the operating efficiency of a typical PEV. This idea is derived from conventional power splitting transmissions to achieve motor efficiency optimization and ultimately lead to running range improvement. Through parameter matching and simulation, results demonstrated that the proposed two motor two speed PEV can realize better vehicle performance than single reducer PEV system; furthermore it can behave even better than a similar single motor two speed system.