Audi A5 and S5 Cabriolet: The Drivetrain
Audi equips the A5 Cabriolet with three different drivetrains. The 2.0 TFSI with 155 kW (211 hp) and the 2.7 TDI come standard with a six-speed manual transmission featuring short throws for precise gear changes. Internal friction is minimal. The two two-liter engines and the 3.2 FSI can be equipped with the multitronic continuously variable automatic transmission. It combines smooth operation, high efficiency and fuel-saving gear ratios. When speed is of the essence, multitronic offers a sport mode and a manual mode with eight simulated gear ratios.
Audi offers the seven-speed S tronic as an option for the stronger of the two 2.0 TFSI engines and the 3.2 FSI. It is standard with the 3.0 TDI. Like a mechanical gearbox, the S tronic uses pairs of gear wheels to create seven gear ratios.
The innovative, high-tech dual-clutch transmission changes gears in only a few hundredths of a second and so serenely that the driver barely notices. Its high efficiency and long ratio in seventh gear have a positive effect on consumption. Drivers can set the seven-speed S tronic to change gears automatically or they can decide for themselves when to shift gears, including by using shift paddles on the steering wheel.
The new seven-speed S tronic is made up of two separate transmissions and integrates two multidisk clutches that control the various gears. The clutch located on the outside directs the torque via a solid shaft to the gear wheels for the odd-numbered gears 1, 3, 5 and 7.
A hollow shaft rotates around the solid shaft. It is connected to the clutch inside the clutch assembly and controls the gear wheels for the even-numbered gears 2, 4 and 6, as well as reverse.
Both transmission structures are continuously active, but only one is connected to the engine at any one time. For example, when the driver accelerates in third gear, the fourth gear is already engaged in the second transmission structure. The change of gear occurs by changing the clutches. The mechatronic module, a compact unit comprising controllers and hydraulic actuators, controls all shift and clutch operations with extraordinary exactness, even when carrying out precise maneuvers.
The power flows from the output shaft to the center differential of the quattro permanent all-wheel drive, which distributes it in two directions. Normally 60 percent flows to the rear differential and 40 percent to the front differential. When a wheel begins to slip, the mechanical center differential instantly and automatically transfers most of the power to the axle with the better traction. Up to 85 percent can be sent to the rear or a maximum of 65 percent to the front. The seven-speed S tronic and quattro all-wheel drive come standard on the top diesel model and are available as options for the two most powerful gasoline models.
Innovation from Audi: quattro with sport differential The new sport differential on the rear axle provides even greater dynamism. The latest Audi powertrain innovation takes driving enjoyment to a whole new level in the A5 Cabriolet with quattro all-wheel drive thanks to the continuously variable distribution of power between the rear wheels.
With quattro with sport differential, the open-top four-seater remains completely neutral in all types of corner as if it were on rails. When steering into or accelerating in a corner, the majority of the torque is sent to the outside rear wheel, which literally pushes the car into the curve. The system thus anticipates and prevents any tendency toward oversteer or understeer, ensuring an even more dynamic driving experience.
Thanks to its extremely short reaction time less than 100 milliseconds the sport differential takes effect even more rapidly than the ESP stabilization system. It is just as effective while coasting as it is under load.
quattro with sport differential is a new type of rear-axle differential. A superposition gear was added to both the left and right sides of the classic differential; it rotates ten percent faster than the wheels drive shaft. Each stage comprises two sun gears and a ring gear offset from one another. This results in a large tooth overlap for high loadability with a minimal number of components.
A multi-plate clutch provides the connection between the drive shaft and the faster-turning superposition gear. It is activated by an electrohydraulic actuator and runs in an oil bath. When the clutch is closed, the higher speed of the superposition gear is applied to the drive wheel. This generates additional torque at the outside driven wheel and torque at the opposite wheel is reduced via the differential. In this way nearly all of the torque can be directed to one wheel. The maximum different in torque between the wheels is 1,800 Nm (1,327.61 lb-ft).
The secret to the effectiveness and fast reaction speed of the sport differential lies in its management software developed in-house by Audi. The controller continuously and quickly recalculates the ideal distribution of torques for each driving system as a function of the steering angle, yaw angle, lateral acceleration, speed and other information.
The functions of the sport differential can also be adapted to the individual requirements of the driver. The comfort mode is aimed primarily at safety and stability, and load changes are optimally damped. Auto mode is programmed for an even balance of all functions. The dynamic mode emphasizes all agility functions. It is here that the improved dynamics due to the sport differential are most noticeable. Load change behavior in this mode is both agile and controllable.
The equipment, specifications, and prices stated herein refer to the model range offered for sale in Germany. Subject to change without notice; errors and omissions excepted.
|