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ALFA TCT – TECHNICAL INFORMATION MODERN TRANSMISSIONS Transmissions are the link between the engine, the vehicle and the driver. As such they act as an interface, which has to optimise the power flow to the wheels according to the driver’s needs. A modern transmission must actively contribute to meeting customer expectations by smoothing the oftenconflicting trends in vehicle and engine evolution. So far the European automotive market has favoured Manual Transmissions (MT), which exhibit high efficiency, low cost and, above all, give full control to the driver. Conventional Automatic Transmissions (AT) are favoured on the North American market and the Continuously Variable ones (CVT) on the Japanese. In these markets comfort and ergonomics are privileged at the expense of lower efficiency, higher fuel consumption and additional weight. Further more, they often exhibit a non-sporty behaviour, an aspect that is not appreciated on the European market. WHY DUAL CLUTCH TECHNOLOGY The

first attempts to bridge the gap between Manual and Automatic transmissions led to the development of the Automated Manual Transmission (AMT), a technology that was pioneered by the Fiat Group. This technology guarantees a combination of high transmission efficiency with optimal use of the engine’s fuel consumption characteristics. Its drawback is the ‘unexpected’ torque interruption during the automated gear shifting that is not appreciated by some users. Dual Clutch Transmission is a step forward. It eliminates the torque interruption, and significantly improves efficiency and drive quality whilst optimising performance and fuel economy. ALFA TCT DEVELOPMENT OBJECTIVES The Alfa TCT transmission has been designed taking into account the current trends in vehicle and powertrain technology. In particular the following aspects have been considered: • Increased engine torque • Engine down-sizing • Engine down-speeding • Tyre over-sizing • All wheel drive

requirements . All the above taking into account the constraints of: • High efficiency • Low weight • Fun to drive DRY vs. WET DUAL CLUTCH TECHNOLOGY Efficiency, weight and Start&Stop compatibility were the main motives for selecting Dry Dual Clutch technology for the ALFA TCT transmission. Dry clutches are significantly more efficient than Wet clutches: they dissipate energy only when they are actuated during launch and gear shift manoeuvres. Wet clutches, on the contrary, dissipate energy even when they are not operating, something that causes so-called viscous drag losses. In addition, Dry clutches are cooled by natural convection to the air. Wet clutches, given their nature and compactness, require forced oil flow for their cooling. This calls for an extra oil pump, with the associated energy losses, nearly three times the quantity of oil and a dedicated oil cooler. All these elements add energy loss and weight, which are avoided in the case of the Dry ALFA

TCT. ALFA TCT: HOW IT WORKS The concept of a Dual Clutch Transmission, such as the ALFA TCT, is comparatively simple. The best way to describe it is to imagine two transmissions placed in parallel (although they are physically concentric), each one with its proper clutch. One handles the odd gears (1st, 3rd and 5th) and the other one the even ones (2nd, 4th and 6th). Gear shifting between two consecutive gears takes place by engaging the desired gear, while the previous one is still engaged, and then switching the power flow from one half-transmission to the other by gradually switching the two respective clutches. The great advantage of this process, compared to conventional torque converter automatics, is that the engine is always mechanically linked to the wheels, something that provides the feeling of immediate reaction of the vehicle to the driver’s commands. This is not just a feeling, it is a real fact that minimises the typical waste of energy of torque converter automatic

transmissions during vehicle launch and gear kickdowns. ALFA TCT: HOW IT IS MADE The ALFA TCT is a six-speed transmission. It weighs only 81 kg, including oil, wiring harness and control unit, a significant weight reduction, approximately 10 kg compared to an equivalent torque automatic or CVT transmission. The 3-shaft transmission design is contained in a 2-piece aluminium housing with an intermediate support plate for the shaft bearings. The gear set housing is characterised by reduced upper secondary shaft length. This is in order to satisfy crash safety requirements which call for the presence of a, rather intrusive, longitudinal crash beam in this zone of the engine compartment. THE DUAL CLUTCH UNIT AND ACTUATION SYSTEM The clutch, as well as gear actuation of the ALFA TCT is based on electro-hydraulic technology. The Dual Clutch Unit of the ALFA TCT is an engineering benchmark in terms of packaging. Its most important characteristic is the adoption of a coaxial pull-rod for

the actuation of the odd-gear clutch. This pull-rod is connected to a hydraulic piston actuator located on the rear face of the transmission housing. The odd gear clutch is normally closed as in conventional manual transmissions and features an integrated wear compensation mechanism. The adoption of a normally closed odd gear clutch was primarily dictated by energy saving considerations; since odd-gear driving exceeds 50% of the vehicle’s mission and is statistically prevailing in urban and extra-urban conditions, the operation of the hydraulic system to maintain the odd-clutch closed was considered inefficient. The even gear clutch is actuated with a comparatively conventional hydraulic cylinder and is forcecontrolled. This choice was again made on the basis of packaging considerations The thermal behaviour of the Dual Clutch Unit has been studied extensively and an accurate physical thermal model has been developed and validated. This model resides in the control algorithms of the

Transmission Control Unit and forms the basis of the torque transmissibility and thermal protection strategies. THE ELECTRO-HYDRAULIC CLUTCH & GEAR ACTUATION SYSTEM The ALFA TCT clutches and gear-shifting mechanisms are electro-hydraulically actuated, guaranteeing high system performance, efficiency and compactness. The system is composed of a hydraulic Power Unit, an accumulator and an Actuation Module. The electric oil pump’s duty cycle in urban driving rarely exceeds 20%, evidence of the system’s efficiency. The clutch and gear actuation module consists of five solenoid valves: two for the gear engagement pistons, and three for the clutches. The Actuation Module also comprises five non-contact linear position sensors that control the gear selected. Great attention has been paid to the intrinsic safety of the actuation system. A significant part of this is ensured by the design of the system itself and the remainder by the relevant control strategies. Additionally to

those measures, the transmission control algorithms continuously monitor the real position of each actuator in order to react in eventual unwanted situations. THE TRANSMISSION CONTROL UNIT The Transmission Control Unit of the ALFA TCT employs the same modern electronic platform used in the recent MultiAir and MultiJet II developments. The most critical control loops are executed every two milliseconds in order to ensure high system performance and reactiveness as well as enhanced safety. TRANSMISSION CONTROL STRATEGIES The transmission control strategies have been developed in-house and run in a multitasking environment in order to meet the frequency requirements of the control loops that they implement. They can be grouped as described below: Actuator controls: The control strategies exploit the high performance attainable with electro hydraulic actuators. Self-tuning controls: The main self-tuning control algorithms concern the conversion of the requested clutch transmitted torque

to clutch position and force; temperature and humidity etc. are fully compensated by these algorithms Launch and gear shift strategies: The ALFA TCT implements various driving modes, depending on the desired performance and driver requirements (Alfa D.NA), both in manual and in automatic mode: • Dynamic / Natural / All Weather • Automatic / Manual (tip) In effect, three different modes of shift patterns in automatic and two different ones in manual mode are contemplated and are accomplished also by specific control strategies and calibrations on the engine side. Vehicle creeping on brake release is also implemented, in collaboration with the braking system’s hill holding functions. The ALFA TCT adopts so-called power based powertrain drivability strategies. While launching or gear shifting, the desired engine torque is defined by the Transmission Control Unit and implemented by the Engine Control Unit according to the concept that, in pressing the accelerator pedal, the

driver requests a certain power at the wheels; it is up to the Transmission Control Unit to define the optimal engine torque and speed mix in order to achieve that. The end result is that the powertrain control is robust and repeatable, whatever the ambient conditions and driver’s performance request. Finally, the integration of the powertrain control with that of the braking system allows the optimal deployment of engine Start&Stop, which is fully compatible with the Alfa TCT characteristics. SUMMARY The ALFA TCT transmission is characterised by: • Highly competitive with CVT and AT concepts in terms of comfort but with significantly higher efficiency and better drivability • Compact, high torque density, design • Dry Dual Clutch technology for high efficiency, lower weight • Electro-hydraulic clutch and gearshift actuation systems for performance and compactness • Start&Stop integration • Integrated Power-based engine and transmission control

strategies for fuel economy, system robustness and seamless gearshift and launching manoeuvres