Okuda, K., Yasuda, Y., Adachi, M., Tabata, A. et al., "Development of Multi Stage Hybrid Transmission," SAE Int. J. Alt. Power. 6(1):77-83, 2017, doi:10.4271/2017-01-1156.
Toyota Motor Corporation developed the Multi Stage Hybrid System for the Lexus flagship LC500h coupe with the aim of achieving an excellent balance between fuel economy and acceleration performance. The Multi Stage Hybrid Transmission used in this new hybrid system includes a shift device located immediately after the power split device and motor.Compared with previous hybrid systems, acceleration performance is improved by increasing the driving force at low and medium vehicle speeds in lower gears, fuel economy and heat management performance are improved by reducing electrical loss by selecting the optimal gear depending on the driving state. The Multi Stage Hybrid Transmission uses a shift device with a wide gear ratio range to maximize both fuel economy and acceleration performance.The transmission was designed to achieve the appropriate size to be mounted in a new platform, as well as class-leading low noise levels for adoption in luxury vehicles. It also includes a quickly responsive and accurate hydraulic control system that achieves excellent shift performance.This paper describes the hardware of the Multi Stage Hybrid Transmission.