Transmissions – automated manual transmissions

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  • Publié le : 26 septembre 2010
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Transmissions panorama – Automated Manual Transmissions positioning for the next years

Abstract: To face the challenges of the car industry, the possibilities that have the car manufacturers on the transmissions is one of their major tools. After several decades during which cohabited the manual and automatic transmissions, a new family appeared, the Automated Manual Transmissions (AMT), whichoffers a new balance of performances and price. The new PSA Peugeot-Citroen automated manual transmissions, called MCp, confirms that a new transmission family now exists for the next years, between the two existing ones, thanks to its performances and its large production . Keywords: Transmissions panorama, Automated Manual Transmission

The transmission has also an impact on the comfort ofthe driver (level of delegation, efforts of handling, comfort during gearshifts) According to the chosen transmission technology, the impact will be strong on the vehicle technical specifications and the price on the one hand, and on the facility to optimize the exploitation of factories on the other hand, by using possible synergies. The strategies that each car manufacturer will take during thenext years will have thus a very big impact on the market of the transmissions for the next decade 2. Transmissions panorama – the stakes 2.1 The transmissions families For several decades, the market of the transmissions has been divided into two families, according to the level of delegation by the driver: • Manual transmissions • Automatic transmissions

1. Introduction The car industry mustface several major stakes that the car manufacturers must take up: • To make progress in automobile technical specifications and performances, for customers increasingly more demanding (fuel consumption, comfort, performances) • To be able to answer to the always more increasing emissions regulations • To propose attractive prices to be competitive • As well as possible, to use the industrialcapacities of its factories The powertrain has a large part in the possible technical answers, by the engine of course, via its intrinsic technical specifications, but also by the transmission It is the transmission, indeed, which: • Control the operating point of the engine (with impact on the vehicle emissions and fuel consumption) • Control the wheel torque (impact on vehicle performance)

2.2Manual Transmissions The manual transmissions are completely controlled by the driver (gear change decision, clutch disengaging, shift actuation, clutch engaging), and a phase of “no-torque” occurs during time when the clutch is open (open drive train) For the customers, the differentiation between different manual transmissions lies mainly in • The number of gears (generally 5 or 6) • The efforts andprecision for the handlings. The technology differences for the manual transmissions are mainly around the number of shafts, the synchronizers, the bearings, the gears, the internal shifting mechanism and the clutch linkage.

2.3 Automatic Transmissions Concerning the automatic transmissions, the driver doesn’t need to think about anything and doesn’t have to do any action to change gear.Moreover, no « no-torque » phase occurs during the gear shifting, because there is always some torque transmitted from the engine towards the wheels of the vehicle. The transmission, via its control unit, decides itself to change gear according to parameters of environment and the behavior of the driver. The transmission also carries out itself all the sequences of gear shifting, differently,according to the technology. For the customers, the differentiation between the automatic transmissions lies in: • The number of speeds (4, 5, 6, 7 or infinite for the continuously variable transmission) • Strategies for change gear decision • Comfort during the gear shifting (acceleration variation, shocks) Three technologies currently divide the market of the automatic transmissions: • Automatic...