INTRODUCTION The first development priority for the new automatic transmission was “Driving pleasure” suitable for luxury passenger cars and sports cars. AW and TMC thoroughly considered which characteristics are needed for the automatic transmission to realize “Driving pleasure” for all drivers. AW and TMC understood that the new automatic transmission needed to realize Rhythmic, Smooth and Direct shift changes for quick and outstanding feeling. AW and TMC have long worked to improve the shift characteristics of existing models; however, the results were limited by hardware design factors. Therefore, AW and TMC decided to develop a brand-new automatic transmission to provide the No1 shift characteristics in the world. To improve vehicle dynamics and fuel economy, mass reduction and increased efficiency compared to competitor’s automatic transmissions were top level design targets. As a result, AWR10L65 realizes lower mass and improved efficiency compared to current 8- speed automatic transmissions. In this paper, the development details for AWR10L65 (AGA0) are described. GEAR RATIO SELECTION To select a gear train structure, AW and TMC performed many case studies of ideal gear ratios to realize “Driving pleasure”. After several discussions, AW and TMC concluded that the following characteristics are needed for outstanding and pleasurable driving feel. • Rhythmic and smooth shift change ( Fig. 1) ◦ Uniform shift interval, Continuous acceleration • Quick acceleration during high speed driving ◦Direct response from throttle pedal, Quick shift change Figure 1. Rhythmic and smooth shift change To realize these characteristics, the following gear ratio settings were chosen (Table 1 ). AW and TMC used optimization programs to investigate gear train systems. Several plans were selected from this analysis and it was finally judged that the 10-speed transmission gear system is optimum to achieve “Driving Pleasure”.New RWD 10 Speed Automatic Transmission for Passenger Vehicles Tomohide Suzuki, Hiroyuki Sugiura, Atsushi Niinomi, and Shingo Maezuka Aisin AW Co., Ltd. Terufumi Miyazaki and Yohei Habata Toyota Motor Corp. ABSTRACT Aisin AW (AW) and Toyota Motor Corporation (TMC) have developed a new rear wheel drive (RWD) 10-speed automatic transmission, AWR10L65 (TMC name: AGA0), suitable for RWD/AWD luxury passenger cars and sports cars. This 10-speed automatic transmission provides enhanced drivability leading to outstanding driver satisfaction. This has been accomplished using a close ratio gear train with optimized gear steps for rhythmic shift changes and quick acceleration. Low rpm lock-up and highly responsive shift changes result in a direct shift feel. This automatic transmission contributes to improved fuel economy by having higher efficiency and lower mass than current 8-speed RWD automatic transmissions. CITATION: Suzuki, T., Sugiura, H., Niinomi, A., Maezuka, S. et al., "New RWD 10 Speed Automatic Transmission for Passenger Vehicles," SAE Int. J. Engines 10(2):2017, doi:10.4271/2017-01-1097.Published 03/28/2017 Copyright © 2017 SAE International doi:10.4271/2017-01-1097 saeeng.saejournals.org 695Downloaded from SAE International by University of British Columbia, Sunday, July 29, 2018Table 1. Optimum gear ratio setting for “Driving pleasure” Fig.2 shows the AWR10L65 (AGA0) gear ratios. The gear step for the 2-3 shift is 1.34, for the 3-4 shift is 1.25 and for the 4-5 shift is 1.29. These optimized cross steps realized rhythmic shift changes. Starting acceleration ability is improved because the 1st gear ratio is 7% lower. The 2nd gear ratio is 9.260 and this lower gear ratio supplies enough driving force to allow for a full lock-up condition from 2nd gear. This helps AWR10L65 (AGA0) provide a direct response feeling to pedal position. The top gear total gear ratio is 1.756 and it is 13% higher than current 8-speed automatic transmissions. This contributes to improved efficiency and quietness at highway speeds. Due