Tateno, H., Yasuda, Y., Adachi, M., Suzuki, H. et al., "Rattling Noise Reduction Technology for Multi Stage Hybrid Transmission," SAE Technical Paper 2017-01-1157, 2017, doi:10.4271/2017-01-1157.
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 the power split device and motor.Compared with existing 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 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. This is a key development item for Lexus vehicles which must meet high customer expectations in terms of silence characteristics, specifically in hybrid transmissions, due to the various components with backlash, which can lead to various rattling noises.This paper describes the technology developed to reduce rattling noise in the Multi Stage Hybrid Transmission.