Mercedes Points to Small-car Future for DCT
Confirmation that Daimler has been working on a program for dual clutch
transmissions in small cars has been provided by the Mercedes-Benz Concept
A-Class, a fresh design study for a compact sporty hatchback displayed at the
Shanghai auto show in April.
The low-slung, two-door Concept also shows that Mercedes has abandoned the high-riding double-floor architecture of the first two generations of A-Class, along with the underfloor engine, long an economic burden on Mercedes as it could only be employed on vehicles with this type of construction.
Instead, as evidenced by this Concept, the next-generation A-Class will have its engine mounted in a more conventional upright position, though still driving the front wheels, and the vehicle structure will also follow the cheaper-to-manufacture standard practice. The transverse motor’s cambox cover is clearly visible in a see-through view put out by Mercedes in the press material for the model.
The new M270 family of four-cylinder, direct-injection engines has been specially developed for the new models. The show car was equipped with a two-liter BlueEfficiency edition rated at 210 hp, most likely one of the top versions. Yet, beyond stating that the gearbox is of dual clutch configuration, Mercedes gives no other details of the transmission, nor has the company stated whether it is an in-house development or a collaboration with an established transmission supplier.
Important questions remain: the number of ratios, the choice between dry, moist or wet clutches, and the method of activation of the clutches and gear selectors. All of these factors can have a significant effect on overall efficiency, and with maximum fuel economy sure to be a high priority on a model set to compete with the Golf and Audi A3, the Mercedes engineers are likely to have developed innovative solutions to enable the new A-Class to offer class-competitive CO2 emissions values. On the other hand, with the 210 hp turbocharged engine expected to also offer a substantial torque output, the transmission could find itself toward the upper end of the torque range capability of a dry clutch solution.
The interior of the concept car also gives
few clues to the details of the transmission. There are conventional shift
paddles on either side of the steering wheel, and the central shift lever –
described by the concept’s designers as taking the form of an aircraft reverse
thrust control – is simply marked with the familiar PRND positions.
For the first time in this segment, Mercedes will offer the new A-Class with a radar-based collision warning system linked to Adaptive Brake Assist and Collision Prevention Assist, a suite of features designed to warn the driver and implement emergency braking to reduce the risk and consequences of rear-end collisions. The provision of these complex systems is another possible pointer to a generally high level of engineering sophistication and the likelihood of significant innovations in the transmission.
Story Filed: 6/07/2011
By Tony Lewin, managing editor DCTfacts.com