Page 1 - Design
Page 2 - Engines and transmissions
Page 3 - Engines and transmissions (cont.)
Page 4 - The chassis
Page 5 - The chassis (cont.)
Page 6 - The body
Page 7 - Comfort and communication electronics
Page 8 - Comfort and communication electronics (cont.)
Page 9 - Standard equipment
Page 10 - Optional equipment
The body
Torsional rigidity boosted by 25 percent: this increase clearly demonstrates the qualities of the new Audi A6 Avant, especially considering that the previous model was already widely acclaimed for its extremely robust body.
Qualities of this kind offer significant advantages in terms of both vibration comfort and driving dynamics. Vibration amplitudes reduced to a minimum are a clear indication of the high standard of strength achieved. These are in turn one of the key physical factors behind the interior's excellent acoustics.
A further crucial factor taken into account during development of the body structure was to maintain the highest possible level of passive safety, in other words to protect the occupants effectively in a collision. At the same time it is important to avoid any increase in weight, since this would also mean an increase in fuel consumption and emissions. The only way to meet these conflicting interests is to use the most advanced materials and joining technologies.
Lightweight design and solidity
The use of high-strength and ultra-high-strength sheet steel makes it possible to reinforce specifically those structural components that are absolutely crucial for ensuring a high level of stability. Lightweight aluminium components such as panels and extruded profiles, on the other hand, help to save a considerable amount of weight.
Sheet aluminium, for example, is the ideal material for the engine hood and front mudguards – as on the previous A6. Aluminium can also be used, however, on large components subject to only moderate loads, such as the lower section of the rigid rear bulkhead or the front panel of the radiator tank.
Used in the form of an extra-strong extruded profile, aluminium can also be used for reinforcement purposes, for example on the side sills, where it stiffens the cell structure for extra safety in a side-on or offset collision.
The front roof frame is a hybrid structure, made from a combination of steel and plastic. This blend of materials combines the positive properties of both materials, providing a lightweight structure with a high degree of solidity.
Tailored blanks or tailored rolled blanks – rolled plates varying in wall thickness – are used at points subject to particularly high loads, such as the suspension strut cross-member or the front longitudinal members.
The various components are connected to each other using a number of different techniques: apart from conventional spot welding, rivets, spot welding combined with bonding, laser welding and soldering as well as MIG welding help to produce a lasting, solid connection. This makes it possible to fulfil a wide range of requirements in every area.
Passive safety
One of Audi's fundamental objectives in developing every model is to make the passenger cell very stiff. After all, this is the basic structure serving as the foundation for all of the car's restraint systems and their protective effect.
One of the most important aspects to consider when designing this cell is behaviour in a frontal impact, by far the most common type of impact in accident statistics. To put it in simple terms, the body development engineers have two main tasks in the area of safety technology: first, to convert kinetic energy into deformation energy absorbed by body components. Second, to ensure that such energy does not even reach the occupants protected within the passenger cell, which must be made as robust as possible.
In a frontal crash, intelligent up-front sensors behind the radiator grille interact with other sensors and control units, registering within just a few thousandths of a second that the car has been involved in an impact. The belt tensioners are then ignited just a few milliseconds later in order to minimise any possible belt slack.
Once the loads acting on the belts have reached a certain limit, a belt force limiter feeds out additional belt length, allowing the occupants to "fall" into the airbag once it has inflated. The full-size front airbags are activated in two stages: in the first stage – activated in accidents at low speeds – forces acting on the occupants are kept at a low level. At higher speeds, the second stage is triggered in order to utilise the full safety potential of the front airbags.
The particular position chosen for numerous elements such as the air conditioning, control units, the ignition lock and key is also an integral part of the car's safety concept. All hard components and surfaces have been moved away from critical impact areas which might harm the occupants; other areas such as the footwells are cushioned by extensive padding. This significantly reduces the risk of injury for the car's occupants.
The safety steering column comes with a double telescoping function, in other words it is – like the pedals – disconnected from any intrusions into the front end of the car. A force limiter at the steering column mounting additionally ensures that the steering column will give along a defined path in response to impact with the driver's chest, causing the steering wheel to move down to prevent injury.
In a frontal crash at low speeds of up to 15 km/h, the highly efficient bumper system serves to minimise energy right from the start, avoiding the need for expensive repairs to the welded body structure behind.
Thanks to the precise deformation of the bumper, even the mudguards remain unharmed in a head-on collision at 15 km/h. Clearly, these are features that insurance companies will welcome and duly reward with a particularly favourable insurance premium.
Safety, too, in a side impact
While at the front end of the car there is ample deformation length, the deformation travel available at the side for absorbing energy is at a minimum. Only a particularly high standard of strength in this area can protect the occupants: this is precisely why the new Audi A6 Avant has a highly stable structure made primarily from dual-phase steel which stands out for its inherent rigidity and the protection it provides against excessive loads and forces.
In the side sill, an extruded aluminium profile ensures effective absorption of energy. Within the doors, tailored blank inner panels, together with reinforcements at shoulder and sill level and an aluminium impact beam, offer substantial resistance to deformation. Several beams arranged perpendicular to the direction of travel likewise serve to stabilise the passenger cell; two high-strength steel pipes also installed laterally in the front seats help to maintain survival space for the occupants.
High-strength reinforcements also extend far into the roof area, serving to protect the occupants in a rollover.
In a collision from the side, the occupants are protected by side airbags fitted as standard at the front (optionally available at the rear) and the head airbag system known as sideguard. The latter covers almost the entire side window area, offering occupants of all sizes a high degree of safety. With the airbags being rapidly filled by a hybrid gas generator and maintaining their pressure for a long period, passenger safety is ensured quickly and lastingly, which means that sufficient safety potential is also ensured in secondary collisions.
Sensors in the doors and C-pillars ensure reliable and rapid activation of the airbags in a collision from the side or an offset impact.
The new Audi A6 Avant is also extremely well protected from the effects of rear impacts. It already satisfies the requirements of future standards. In other words, it withstands impact with a deformable barrier at up to 80 km/h and at least 70 percent overlap.
In such a collision both the passenger cell and the fuel tank remain outside the actual deformation area. The entire rear structure of the car undergoes deformation according to a defined pattern with the aid of large impact members, thus absorbing impact energy.
Active head restraints in the front seats protect the driver and front passenger from the consequences of a rear-end collision. Released mechanically, the head restraints move forward to reduce acceleration of the occupant's head as soon as possible as it shoots back.
Aerodynamics and aeroacoustics
More interior space, a wider track: the new Audi A6 Avant is significantly larger than its predecessor. Since this also means a larger frontal area, the task of the aerodynamics engineers was to compensate for this fundamental drawback with particularly intelligent design of the car's outer skin. And Audi's aerodynamics engineers have successfully mastered this challenge, achieving a drag coefficient (Cd) of just 0.31 for the new Audi A6 Avant 2.4.
Compared with its predecessor, which was also already developed to a very high standard of aerodynamic excellence, the overall drag factor (Cd x front area) of the new A6 Avant has been improved, depending on engine version, by 9 to 13 percent. And compared with its competitors, too, the A6 Avant is one of the leaders in terms of aerodynamic efficiency.
One feature that is particularly important in terms of aerodynamics is the full underbody panelling. Encapsulation of the engine compartment and transmission at the front end ensures a swirl-free flow of air to the central floor area, while wheel spoilers reduce flow losses around the front wheels. Large cover panels optimise the flow of air along the transmission tunnel all the way back to the rear wheels.
In all, the various improvements on the underfloor of the car reduce the drag factor by no less than 0.031 which, related to the car's overall drag coefficient, means an improvement of almost 11 percent.
Thanks to its aerodynamic underbody, this means that at a speed of 180 km/h the Audi A6 Avant consumes around six percent less than a comparable vehicle without a correspondingly modified underside.
Adaptive headlights and daytime running lights
Audi offers no less than two new features behind the clear-glass covers of the A6 Avant’s headlights: the dynamic technology of adaptive light, and daytime running lights in conjunction with xenon plus technology. The combination of these systems is an absolute world premiere, a USP offered only by Audi.
The new A6 Avant, too, comes with light units in Audi's typical "tube" look. Featuring anthracite-coloured trims, the tubes for the high and low beams appear to hover almost freely in the air, giving the front-end design of the car its very own touch of high-tech.
The headlights on the new A6 Avant come in three different versions: standard halogen headlights in free-form technology, xenon plus headlights and the xenon plus system with the dynamic adaptive light system that “see�' around bends. It does this by pivoting the ellipsoidal module for the high-beam and low-beam headlights in synchronisation with the line of the road or a bend as the car is driven. This greatly improves illumination of the road in front of the vehicle and to the sides, making it easier for the driver to anticipate the course of the road ahead.
On the basis of several parameters including vehicle speed, steering angle and yaw rate, the system’s control function calculates the necessary change in the position of the headlights and communicates the necessary signals to the drive motor.
Daytime running lights for extra safety
The significant safety advantage provided by permanent operation of the headlights throughout the day was previously associated with increased energy consumption, with an extra 0.2 litres of fuel being consumed every 100 kilometres driven. This is why, with the exception of just a few countries, this technology is yet to be introduced throughout Europe. Yet there is evidence that daytime running lights help to enhance driving safety, particularly when the sun is low or when driving on the motorway or in built-up areas.
With the low and high beams in the xenon plus headlights being integrated into the same – the outer – unit, the inner reflector remains free for the use of daytime running lights. A dimmed bulb serves as the source of light, while the other lights are switched off. An increase in fuel consumption is practically eliminated.
LED rear lights
Alongside the basic version which uses conventional bulbs, the rear lights of the new A6 Avant are available with an LED unit for the brake and tail lights as an option in conjunction with xenon plus.
As well as a long operating life of at least 10,000 hours and energy consumption reduced by up to 80 percent, this main advantage of this technology is a much shorter response time. Whereas conventional bulbs take around 200 milliseconds to reach their full brightness, LEDs achieve their full output in less than one millisecond. Drivers following behind will thus recognise much more quickly that the brake lights have come on.
The LED unit for the tail lights also adds a striking, sporty touch at the rear of the car, their horizontal arrangement producing a wide and flat appearance.
Related entries:
New Audi A6 - In Depth
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