Analysis of Hybrid Electric Transmission with Over Ten Speed Ratios

A hybrid transmission with more than 10 times speed ratio is introduced in this paper. The transmission consists of a electric torque converter module (eTC) and a dual input-shaft gearbox (DIG). The configuration structure and operation mode of the hybrid system based on eTC-DIG are analyzed in detail. The hybrid module comprises a motor, a planetary gear set (PGS), and a clutch. The rotating elements of the PGS are connected to engine shaft, motor shaft, and two input shafts of DIG, respectively, in such a way, that a new speed ratio is created between each odd-numbered gearset and an adjacent even-numbered gearset. The transmission has twice as many speed ratios for the engine as the number of the speed-changing gear sets. The hybrid system can realize a variety of working modes and eliminate the dual clutch of DCT, which greatly reduces the cost and risk. The economic simulation of the hybrid system is carried out for a Pickup truck. The results show that multi-gear is conducive to optimizing the engine working area, and the fuel consumption of WLTC cycle is reduced by 28%, which greatly improves the fuel economy of the vehicle and has a good market application value.