In addition to the new gasoline and diesel engines, Mazda’s SKYACTIV technology portfolio includes new transmissions (automatic and manual), body and chassis technology. At a media workshop last week in Vancouver, Canada, Mazda engineers stepped through the highlights of the new SKYACTIV systems. (Mazda hosted Green Car Congress at the event.)
The new SKYACTIV-Drive automatic transmission features full range direct drive.
SKYACTIV-Drive six-speed automatic transmission. The new six-speed automatic (which is being applied in the Mazda3/Axela commencing production in Japan, combines the advantages of continuously variable (CVT), dual clutch and conventional automatic transmissions.
The heart of SKYACTIV-Drive is a newly-developed six-speed torque converter with a full range lock-up clutch for all six gears that Mazda calls “full range direct drive”. The lock-up clutch ratio has been raised from 64% from the current five-speed automatic to 88% during vehicle operation.
The early lock-up between engine and transmission by the torque converter (which enables engine output to be sent directly to the drive wheels) inhibits the characteristic loss of power during acceleration, delivering a more direct driving feel. Preventing engine output loss also improves fuel economy; Mazda calculates that the new transmission improves fuel economy by up to 7%.
High-precision hydraulics are required to support such a design. In order to make the necessarily fast and accurate oil pressure modulation possible in the first place and improve reliability, Mazda furnished SKYACTIV-Drive with a new mechatronics module.
The mechatronics control module is integrated into the transmission case, and features new software and new direct linear solenoids. Benefits include improved shift response and quality, higher precision, and less hydraulic fluctuation.
While maximizing the lock-up range is necessary to improve the driving feel and fuel economy, a negative effect is an increase in NVH (noise, vibration and harshness) because there is nothing to absorb the difference in the rotational speeds of the engine and transmission. Mazda developed a new torque converter to resolve this conflict. The expanded lock-up meant the role of the torus piece was confined to very low speeds. Therefore, it became smaller and thus creating space for an improved damper as well as a multi-disk lock-up clutch and its piston, which improve clutch durability and control.
SKYACTIV-Drive is available in two versions—a mid-sized version for up to 200 lb-ft (271 N·m) of torque, and a large version for up to 340 lb-ft (461 N·m) of torque—making the automatic transmission compatible with both SKYACTIV gasoline and diesel engines.
SKYACTIV-Drive automatic transmission.
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