A new-generation highly-efficient automatic transmission that achieves excellent torque transfer efficiency through a wider lock-up range and features the best attributes of all transmission types
Features of SKYACTIV-DRIVE
・Combines all the advantages of conventional automatic transmissions, continuously variable transmissions, and dual clutch transmissions
・A dramatically widened lock-up range improves torque transfer efficiency and realizes a direct driving feel that is equivalent to a manual transmission
・A 4-to-7 percent improvement in fuel economy compared to the current transmission
All the Advantages of Conventional Step CVT, Dual Clutch, and Step AT
Automatic transmissions (AT) can be categorized into three types:
・CVT: generates various gear reduction ratios with a pair of pulleys
・Dual Clutch: utilizes 2 separate clutches for odd and even gear sets.
・Conventional AT: generates various gear reduction ratios with planetary gear sets
The key requirements for ATs are “good fuel economy”, “quick start-up” (including hill climbing), “direct feel” and “smooth shifting”.The table below shows the drawbacks and advantages of each transmission.
SKYACTIV-DRIVE is the ideal AT with all the advantages of the various types of transmissions:
fig.1:Advantages of each transmission type
Improvement in Fuel Economy and Achievement of Direct Feel with Full Range Lock-Up
The torque converter transfers engine power to the transmission through fluid, making a smooth start-up and gearshifts possible. The drawback is that fuel economy worsens due to the loss of power transfer through the fluid, and slippage during rapid acceleration, which causes vehicle speed to lag behind engine speed. Therefore, a torque converter with a lock-up clutch was developed, which locks the torque converter's turbine to the impeller to improve fuel economy and direct drive feel. To improve fuel economy and direct drive feel pointed as challenges of Step AT shown in Fig.1, the lock-up range has to be maximized. However, in order to do so, we had to ensure NVH performance and clutch reliability.
fig.2:Full range lock up
With extensive analysis, Mazda overcame NVH by improving the engine, mounts, exhaust, body, and system control as well as the AT itself. Furthermore, improvement in clutch response and precise lock-up control ensures reliability by preventing heat buildup due to slippage.
*The applications and numerical analysis each technology depend on such models, grades and specifications of vehicle.