Search Results

Upon the need of a highly efficient transmission system for conventional cars and the hybrid electric vehicle (HEV) purposes, in the paper, clutchless geared transmission system (CGST) by removing the clutch and incorporating a planetary gear system connected to a motor is newly proposed. The dynamic analysis of CGST operations is carried out, using the lever analogy of planetary gear. The state space model and the mathematical model of CGST structure are derived. Through the simulations of CGST operations, input-output tests and gear shifts are performed. To verify the simulation result, reduced size of CGST testbench is developed and experimented.

Anti-lock brake systems (ABS) are now widely accepted and used on more and more motor vehicles. With the consideration of low product cost and technologies currently available, standard ABS has only wheel speed sensors to detect wheel angular velocities, not enough to directly obtain wheel slip ratios needed by control unit, but to calculate reference slip ratios with measured wheel angular velocities and estimated vehicle speed. Therefore, the road friction coefficient, which dominates vehicle deceleration during severe braking, is an important parameter in estimating vehicle speed. This paper analyzed wheel acceleration responses in simulations of severe braking on different road surfaces, and selected a pair of specific points to mark the wheel acceleration curve under each certain operating condition, such as road surface, pedal-braking torque and wheel vertical load.