Recently, 5-speed automatic transmissions have become mainstream through the world, and 6-speed automatic transmissions have also been introduced in the market. Consequently, the issue of shift control is gaining importance, and a trend toward increasing number of gears in automatic transmissions has become apparent. On the other hand, weight saving and downsizing of the transmission, including the hydraulic control unit, are strongly required in order to promote fuel efficiency. To meet these requirements, an electro-hydraulic control unit offering sophisticated functionality desired in order to provide excellent shift quality.
As an answer to these requirements AISIN AW developed two types of new 6-speed automatic transmissions in 2002: “TR-60SN” for RWD vehicles and “TF-60SN” for FWD vehicles. Both TR-60SN and TF-60SN have the same structural characteristics.
For the control strategy of these new automatic transmissions, an advanced electro-hydraulic control system has been developed that can ensure both one-step shifting and skip shifting by making use of the characteristics of this unique gear train structure. Flexible shifting can be realized by controlling each clutch pressure by the respective linear solenoids, in combination with use of the electric control unit. Additionally, Lock-up control and Neutral control is incorporated in the system to improve fuel efficiency.