December 12, 2002
Volkswagen introduces first dual-clutch gearbox in a production car
Wolfsburg, Germany – Volkswagen will introduce a new direct-shifting 6-speed automatic gearbox “DSG” with an integrated dual clutch in the Golf R32 in the first quarter of next year. Its use will be extended to other production cars in the course of the year 2003.
The DSG does not employ a torque converter for a standing start. Nor is the DSG a derivative of the automated manual transmission used in the Lupo 3L TDI. Rather, the DSG engineers took a technically revolutionary path by harmonising the agility and fun of a manual transmission with the ease of a conventional automatic gearbox.
Volkswagen says the DSG has advantages in fuel economy and performance over other gearboxes. It offers identical acceleration and top speed, it shifts as smoothly as the best automatic gearboxes of the familiar construction, and manual shifting is possible using the Tiptronic function or, in the Golf R32, buttons in the steering wheel. Shifting occurs faster and more “crisply” than with either manual or automatic gearboxes, stated the company. The DSG in the Golf R32 enables tangibly better performance because the tractive power is not interrupted during acceleration. The so-called launch control, which can be activated at the push of a button, enables an optimal sprint from a standing start without driver intervention.
One design characteristic of the transversally mounted gearbox is a pair of wet clutches with hydraulically controlled pressure. The so-called clutch 1 (C1) serves the odd gears (plus reverse) and clutch 2 (C2), the even ones. For all intents and purposes, it is two parallel gearboxes in one. During a shift, there is no interruption of tractive power, typical of an automated manual transmission.
Together with Mechatronic, an intelligent hydraulic and electronic gearbox control, the two wet clutches with two input and output shafts are responsible. This interconnection enables the next gear permanently to be engaged and ready for activation. For example: While the car is being driving in third gear, fourth gear is already engaged, but is not yet active. As soon as the ideal shift point is reached, the clutch for third gear opens while the other closes, activating fourth gear. The opening and closing of the clutches coincide in the process, producing the smooth shift already mentioned above. The entire shift process is completed in a few hundredths of a second.
Volkswagen claims acceleration times are better than for the model with a manual gearbox. Equipped with DSG and launch control (an electronic start program), the Golf R23 sprints to 100 km/h (about 61 mph) in only 6.4 seconds (with manual gearbox in 6.6 seconds). The top speed of 247 km/h (about 151 mph) is at the same level. Despite the improved performance, the fuel consumption of 10.2 litres per 100 km lies 1.3 litres under the value for the R32 with a manual gearbox.
With the DSG, Volkswagen is the first manufacturer to develop a dual-clutch gearbox ready for production. Such gearboxes have already been used in motor sports, but the uncomfortable shifting due to inadequate means of mechanical and electronic control made them unacceptable for use in production cars.
The DSG will be manufactured in the Volkswagen gearbox factory in Kassel, where the company invested 150 million Euro in the production facilities. Production capacity is up to 1,000 DSG per day.