To help meet its goals of improving fuel efficiency and reducing CO2 emissions, Hyundai has completed the development of an all-new six-speed automatic transaxle that will boost fuel economy by more than 12.2 percent.
Designed for transverse engine applications in passenger cars and SUVs, the new compact transaxle puts Hyundai into an elite class of auto manufacturers who have designed their own six-speed automatic (after Toyota and a GM/Ford joint venture), demonstrating Hyundai's advanced powertrain engineering capabilities.
"The strength of our design is its completely unique layout, which makes it smaller, more compact and lighter than any other six-speed on the market today," said Hong-Min Kim, the project manager of the transaxle at Hyundai R&D Centre. In fact, the design is so unique and so advanced, Hyundai has applied for nearly 300 patents related to the technology.
The transaxle will first arrive in the new Hyundai Grandeur equipped with a 3.3-litre V6 petrol engine. In this application, it delivers a 12.2 percent gain in fuel economy and is 2.5 percent quicker in zero to 62mph (100km/h) acceleration times (7.8sec versus 8.0 sec). It also delivers an 11 percent improvement in 60km/h to 100km/h overtaking performance (4.0 sec versus 4.5 sec).
The unit is also maintenance-free: the gearbox is 'filled for life' with automatic transmission fluid and needs no topping up, reducing servicing costs.
Developed over a four-year period, this new six-speed automatic gearbox offers numerous technical merits. Despite the extra gear, it is 12kg lighter than the five-speed it replaces. It is also 41mm shorter and considerably simpler having 62 fewer parts, which is a key to increased durability and lower cost.
When it comes to gearsets, more is definitely better. The addition of a sixth gear enables closer spacing between 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 whose hallmark is simplicity of design and a unique flat torque converter, which shortens the unit's overall length by 12mm. Four pinion differentials improve durability and further minimise size.
Another example of engineering ingenuity is to be found in the design of the hydraulic pressure control unit. There are always slight manufacturing deviations from one solenoid valve to the next, which cause fluctuation in the hydraulic pressure and affect shift precision and quality. To rectify this, the transaxle features cleverly integrated adjustment screws in the valves which enable each of the eight valves to be calibrated at the factory.
This novel feature ensures stable hydraulic pressure at any shift point, which facilitates a high degree of precision and control needed to deliver ultra-fast, smooth and precise shifts throughout the engine speed range.
The new six-speed went into production this month (December 2008). A total of five variants of the transaxle will be produced to accommodate a wide range of petrol and diesel engines. A total of 16 different Hyundai models will get this transmission including a redesigned Santa Fe, which is due to arrive in late 2009 and early 2010 in some markets.
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