|New Hyundai 6-speed. Click to enlarge.
To help meet its goals of improving fuel efficiency and reducing CO2 emissions of its vehicles, Hyundai Motor Company has completed the development of an all-new 6-speed automatic transaxle for transverse engine applications that it says will boost fuel economy by more than 12.2%.
Despite the extra gear, the 6-speed—which was in development for four years—is 12 kg lighter, is 41 mm shorter and has 62 fewer parts than the 5-speed it replaces. The new 6-speed went into production this month and will see its first application in Grandeur/Azera models equipped with the 3.3-liter V-6 Lambda gasoline engine beginning in January 2009.
In this application, the new 6-speed unit delivers a 12.2% gain in fuel economy (10.1 km/L versus 9.0 km/L; 23.8 mpg US versus 21.2 mpg US) and is 2.5% quicker in zero to 100 km/h acceleration times (7.8 sec versus 8.0 sec). It also delivers an 11% improvement in 60 km/h to 100 km/h passing performance (4.0 sec versus 4.5 sec).
The unit is filled with an automatic transmission fluid that is good for the life of the vehicle thereby reducing maintenance costs. Hyundai has applied for nearly 300 patents on the transmission.
The strength of our design is its totally unique layout which makes it smaller, more compact and lighter than any other 6-speed on the market today.—Hong-Min Kim, the project manager of the transaxle at Hyundai Motor’s R&D Center
The addition of a sixth gear enables closer spacing between gear ratios providing a better balance of performance and fuel economy while the wide overall gear ratio helps deliver strong acceleration.
The gearbox has three planetary gearsets and a unique flat torque converter which shortens the unit’s overall length by 12 mm. Four pinion differentials improve durability and further minimize size.
Integrated adjustment screws in the solenoid valves enable each of the eight valves to be calibrated at the factory to compensate for slight manufacturing deviations from one solenoid valve to another, which can cause fluctuation in the hydraulic pressure and affect shift precision and quality. This design feature ensures stable hydraulic pressure at any shift point, supporting a high degree of precision and control needed to deliver ultra-fast, smooth and precise shifts throughout the rpm range.
A total of five variants of the 6-speed transaxle will be produced to accommodate a wide range of gasoline and diesel engines. A total of sixteen different Hyundai models will get this transmission including a redesigned Santa Fe, which is due to arrive in late in 2009 and early 2010 in some markets.