Design & Technology
Independently developed 6-speed automatic transmission April 27th, 2009
By Seong-hoon Park, Senior Research Engineer
Automatic Transmission Design Team
Hello Kia BUZZ readers!
My name is Park, Seong-hoon and I’m a senior research engineer at Kia and part of the Automatic Transmission Design Team that developed the automatic transmission for Kia’s existing new line of vehicles.
Let’s talk about the development of our newest transmission and its significance for our cars.
The front-wheel drive 6-speed automatic transmission delivers high fuel efficiency and low CO2 emissions. Kia is one of only three global automakers in the world to develop the transmission as part of a strategy to secure and lead core technologies suitable for a sustainable future.
Oil prices have prompted consumers to regard fuel economy as an important consideration when buying a car along with the need for responsible, eco-friendly purchase decisions.
Early on, we recognized the need to secure transmission technology. Since we are localizing those related technologies, we managed to develop our own 4-speed and 5-speed transmissions.
Continued efforts in R&D led to the in-house development of a 6-speed automatic transmission. This feat has not only enhanced our brand image but will produce hundreds of billions of won in savings every year by eliminating the need for reliance on outside technology. We have also secured the latest cutting-edge technology for automatic transmissions.
What are the major features?
The biggest feature on the front-wheel drive 6-speed automatic transmission is a completely unique layout for which we secured 300 patents during the development process. We joined an elite class of automakers (following Toyota and a GM/Ford joint venture) who have this proprietary technology which improves fuel economy/performance and shift quality versus the previous generation’s 5-speed transmission.
[Photo of 6-speed automatic transmission]
Compared to the 5-speed, the 6-speed automatic transmission applied to the new Sorento in Korea, for example, has 62 fewer parts, is 41mm shorter in length and 12kg lighter in weight, making it the most compact 6-speed transmission currently available. It produces a 10% improvement in fuel economy (14.1km/ℓ), 14% faster zero to 100km/h acceleration time (10.0 sec.) and 24% quicker 60km/h to 100km/h passing performance (5.0 sec.) (based on the Sorento diesel R-2.2 2WD).
The Theta 6-speed transmission for gasoline engines delivers an impressive 10.9 sec. acceleration time, 5.9 sec. passing performance and 10.7km/ℓ fuel economy.
What’s the difference between the previous 5-speed automatic and 6-speed automatic transaxle?
The new transmission provides better ride and acceleration during high-speed driving. The extra gear provides better balanced performance during driving, thereby reducing the impact of shifting gears to deliver a more comfortable ride and quicker acceleration.
Fuel economy has been greatly enhanced. The extra gear means the engine doesn’t have to work as hard at high speeds, and thereby reducing fuel consumption.
For these reasons, the 6-speed transmission was previously only applied to premium lines like the Mohave (Borrego).
What are som of the key new technologies applied to the 6-speed automatic transmission?
The unique layout with three planetary gearsets and an ultra flat torque converter shorten the unit’s overall length by 12mm. Four pinion differentials improve durability while the hydraulic deviation adjustment valve body enhances shift quality. The low-viscosity automatic transmission fluid (ATF) and torque converter slip lock-up raise fuel efficiency.
[Ultra flat torque converter]
[4-pinion differential gears]
[Hydraulic deviation adjustment valve body]
In particular, the application of ATF and elimination of ATF level gauge (dipstick) reduces the need for maintenance and leads to further savings for customers.
What is the future application plan of the 6-speed automatic transmission?
The front-wheel drive 6-speed automatic transmission that was developed with 100% proprietary technology will be also applied to other Kia models, including the Opirus (Amanti) and Grand Carnival (Sedona).