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Audi is a founding partner of Nico Rosberg’s GREENTECH FESTIVAL. Under the motto “A story about tomorrow,” the company is showing how it is striving to achieve its self-defined vision of net CO2 neutrality by 2050. The company is taking measures along the entire value chain in pursuit of this goal. In addition, the Audi Q4 Sportback e-tron concept show car is making its show debut at the festival. It provides a tangible look at the brand’s first electric car in the compact segment and is the gateway to the world of premium electric mobility. Strategic partnerships with Climeworks and the Audi Environmental Foundation underscore Audi’s efforts to help achieve the Paris climate goals.

 

Now is the moment: get going with a career! Around 420 apprentices and 23 dual study undergraduates are starting their professional careers today at Audi in Ingolstadt.

 

How do you provide a large SUV with sporty road-holding properties and minimal body roll without impairing ride comfort? Audi has resolved this conflict of objectives by means of electromechanical roll stabilization (eAWS). Assisted by the 48-volt onboard electrical system and powerful actuators, the stabilizers on the front and rear axle can be actively controlled according to the driving situation.

As a result, the models retain their high level of ride comfort in straight-line driving. By contrast, in cornering and load alteration situations, they impress with enhanced lateral dynamics combined with minimal body roll. The technical advantages of Audi’s electromechanical solution: it is energy-efficient, operates in near-real-time and is maintenance-free due to the absence of hydraulic elements.

What challenges do large SUV models pose to chassis engineers?

Customers of large SUV models are thrilled by the many practical talents they offer – from ample space in the cabin to cutting-edge chassis technologies to powerful engines and advanced control and assistance systems. 

Plus, an SUV delivers superb off-road performance. Due to their design, these vehicles feature a higher curb weight and a higher center of gravity. This means that the body of an SUV leans more toward the outside in cornering than it does on models with a lower center of gravity.

What technology counteracts body roll and body movements?

In cornering, the body leans toward the outside due to the centrifugal forces, in other words, the wheel on the outside of the corner goes into jounce travel while the one on the inside of the corner goes into rebound – the vehicle rolls around its longitudinal axis. Torsionally flexible anti-roll bars between the left- and the right-hand side of the axle are proven means of compensating for this effect. They reduce the body’s tendency to roll by applying reverse torsion torque to the suspension on the outside and inside of the corner, thus counteracting the body’s tendency to roll. This passive suspension component has the same effect in both cornering and straight-line driving. However, an effect that is desirable in cornering may impair ride comfort in straight-line driving on roads with bumps or potholes on one side of the surface. 

While passive solutions reach their limits here, Audi has resolved this conflict of objectives by means of electromechanical roll stabilization. Using sensors to capture and detect the situation, the system will intervene with pinpoint precision only when less body roll is desired. Thus, the spring rate of the stabilizers on uneven and straight roads is lowered to a basic level and the spring and damper forces act by and large independently on the left- and right-hand wheels.

How does electromechanical roll stabilization work?

A conventional stabilizer operates passively, in other words, it just balances the suspension movements on both sides by means of mechanical coupling. By contrast, electromechanical roll stabilization can be specifically controlled. The system consists of two stabilizer halves per axle, with an electric motor operating between them on both the front and rear axle. It can rotate the stabilizer halves in opposite direction of each other and thus generate torque that counteracts body roll torque – individually for each wheel. As a result, it reduces the body roll angles and actively supports them against the physical effects of the driving situation. 

The system receives its commands via control units on the front and rear axle, which are part of the Electronic Chassis Platform (ECP). The ECP is the central brain of the chassis. Within milliseconds, it matches a variety of parameters such as speed, ride height, roll and pitch movements of the car, the friction coefficient of the road surface, the current driving condition such as under- or over-steer, plus the data of the chassis systems involved. From this input, the system calculates the ideal responses for the integrated components and adjusts them quickly and precisely to each other. 

The required electrical energy is supplied to the eAWS by a powerful 48-volt onboard electrical system. Within milliseconds, the system calculates suitable actuation values for the stabilizers. The electric motors deliver their power output via three-stage planetary gearboxes, with torque levels of up to 1,200 Nm being generated at the stabilizers.

What is “Vorsprung durch Technik” in the case of an electromechanical solution?

The 48-volt system enables an immediate system response even at low speeds. Latency between the sensors detecting body roll and the response by the electric motors is just a few milliseconds. 

Unlike hydraulic solutions, the eco-friendly electromechanical system does not require oil circuits and is maintenance-free. It is even able to recuperate energy by capturing suspension impulses on its electric motor, converts them into electrical energy and stores it in the lithium-ion battery of the onboard electrical system. The electromechanical solution uses energy more efficiently as well. In contrast to hydraulic circuits, it does not have to store and provide pressure.

How does the driver benefit from the system?

The system reduces the body’s tendency to roll, provides a sportier and more confident handling impression and thus emphasizes the versatile character of the large Q model ranges. It can actively distribute roll torque to the front and rear wheels and thus influence the car’s intrinsic steering characteristics such as the tendency to under- or oversteer. The Audi drive select driving dynamics system offers various setup options for this. Electromechanically active roll stabilization imparts to the driver a dynamic and precise feel in any situation and enables enhanced handling characteristics. It is one of various systems that perfect the dynamism of the top-end models of the Q range. 

The Q7*, SQ7*, SQ8* and RS Q8* models with their controllable stabilizers always respond to the driving situation precisely as expected by the driver. On uneven road surfaces, the body movements are reduced while ride comfort increases. In sporty driving and at high cornering speeds, the car feels more stable and at ease. It pushes itself into a bend in the road. Audi has deliberately selected a setup that does not completely neutralize the roll angle but continues to impart an authentic feel of the driving dynamics situation.

Article source: www.audi-mediacenter.com

 

Four years ago, Audi put a trendsetter on the road with the Q2, and it was a huge success. Now the compact SUV is showcasing its progressive character even more clearly – with an even more striking profile with new headlights on the outside and additional Audi connect services and driver assist systems on the inside. The Audi Q2 is a real eye-catcher – and now it is even more fun to drive.

 

For four decades, Audi has been setting the pace with permanent quattro all-wheel drive and thus initiated a paradigm shift in powertrain technology in the automotive world and in motorsport. The brand is now using the knowledge it has accumulated in this area since 1980 for the next step. The electric quattro in the models of the e-tronrange marks Audi’s next milestone achievement in the age of electric mobility. Enjoyable driving and efficiency are fused into a total package.

Audi combines quattro and e-tron into a powerful combination of high performance and notable economy. The company mass-produces an all-wheel drive system that is highly variable, dynamic and precise while making efficient use of the available energy.

Why does Audi use electric all-wheel drive?

“For us, the electric quattro is the perfect combination of powerful performance and high efficiency,” says Michael Wein, Project Leader All-Wheel Drive Control Systems. “We combine the efficiency advantages of a driven axle with the traction and dynamic performance of an all-wheel drive system.” 

In the current e-tron model range, only the rear wheels propel the car in good traction conditions, while the motor for the front-wheel drive concurrently runs without being energized. Since the motor is an asynchronous type, there are no inherent electrical drag losses, so that this drive layout consumes a correspondingly low amount of energy. The front axle – within milliseconds and unnoticeably for the driver – is additionally activated only as needed – for instance, when there is a demand for high driving dynamics, high torque transfer, or in the case of a low coefficient of friction due to wetness, mud or snow.

What is so unique about electric quattro drive compared to competitors?

Audi is the first manufacturer to enable highly variable torque distribution in the e-tron S due to the drive topology featuring one motor at the front axle and two electric motors installed in a housing on the rear axle. In combination with sophisticated control and regulation, the electric quattro, due to its single-axle operation with variable, unnoticeably additional activation of the front axle, resolves the conflicting aims of dynamic performance and efficiency. 

Audi integrates functions such as electric torque vectoring on the rear axle, wheel-selective torque control due to a braking intervention with the mechanical differential, and high recuperation performance in an electric powertrain. Additionally, drivers can adjust the high variability of the system to their personal preferences by individual program selections.

When do e-tron and e-tron S models activate their electric all-wheel drive?

The electric all-wheel drive is active in situations of degrading grip on road surfaces with low coefficients of friction, in particularly dynamic driving conditions, when the driver demands high traction power, or when maximum recuperation is desired – in other words, the recovery of energy during braking and deceleration. If the driver decelerates the car to a level of 0.3 g, the electric motors act as generators, using the car’s kinetic energy and converting it into electrical energy which, in turn, charges the battery. This applies to more than 90 percent of all braking maneuvers in everyday driving situations. Only when stronger pedal pressure is applied, the system additionally and seamlessly activates the hydraulic wheel brakes. For instance, in a braking event at 100 km/h, the e-tron S can recover kinetic energy with output of up to 270 kW, compared to 250 kW in the Formula E electric racing series. If the driver demands full power while accelerating, the e-tron S models provide a total boost of 370 kW and torque of 973 Nm. Whether in drive or recuperation mode: interconnected control models always select the best torque distribution.

What opportunities does electric quattro open up compared to conventional all-wheel drive?

In the Audi e-tron models, one electric motor each drives the front and rear axle. By contrast, the e-tron S versions use one motor on the front axle and two on the rear axle. With electric torque vectoring – in other words, specific torque development left and right – the e-tron S provides quattro drive on the rear axle with even greater agility.

The key advantage: Without a mechanical connection between the two electric motors on the rear axle, the functions of a controlled transverse differential lock and thus the functions of a sport differential have been achieved within a single system purely by means of software-based activation. 

Consequently, thanks to intelligent drive control, Audi has implemented active and fully variable torque distribution in transverse direction on the rear axle.

How did Audi achieve this high variability in the electric drive system?

Audi combines an electric powertrain architecture – a novelty in high-volume production – with sophisticated control units in which all the key software components and their network integration have been developed in-house.

Compared to a mechanical all-wheel drive, this results in a fast-response drive system. For instance, latency in the case of electric torque vectoring – in other words, the time gap between the sensor measurement and active torque distribution – amounts to just 30 milliseconds. This is merely around a fourth of the response time of a mechanical system. In addition, electric drives provide clearly higher torque levels. Up to 220 Nm more torque can be allocated to the outside wheel in a cornering situation which, due to the transfer ratio, equates to as much as 2,100 Nm per wheel. This is how the drive system generates the desired yaw moment in cornering: The car correspondingly rotates around the vertical axis in the cornering direction and thus feels particularly agile.

When the coefficient of friction on snow or ice is low, traction can be optimized with great precision as well: The respective friction coefficient of the driven wheels is measured and, due to the torque allocation, used in an ideal way, thus enhancing overall traction.

How is this precision control achieved?

Intelligent interlinking is the prerequisite for this software function. The drive control unit (DCU) distributes torque between the electric motors. The best possible energy conversion efficiency is decisive for optimizing efficiency. The integrating control unit of the Electronic Chassis Platform (ECP) uses sensor signals to monitor the car’s driving condition and calculates the ideal distribution of longitudinal and lateral torque. It integrates the vehicle dynamics control of the quattro, in other words, electric torque vectoring as well as wheel-selective torque control via the braking intervention on the front axle.

At the dynamic limit, on the e-tron S, the wheel brake slightly decelerates the inside front wheel in cornering and on the e-tron, the front and rear wheels. Thus, via the effect of the mechanical axle differential, more torque is distributed to the outside and the car follows the steering command in the cornering direction with particular agility. The traction control system (TCR) acts at one-millisecond intervals. This is achieved because individual functional components of the electronic stability control (ESC) have been shifted into power electronics directly on the electric motors. 

Can the driver influence the characteristics of the electric quattro?

Drivers can adapt the electric quattro as desired via two controllers. The Audi drive select system, which is standard equipment for the e-tron models, offers seven profiles: comfort, auto, dynamic, efficiency, individual, allroad and offroad. Thus, among other things, the electric all-wheel drive as well as the suspension and other systems can be adapted to the road conditions and personal preferences. 

The electronic stability control (ESC) system contains four programs: Normal, Sport, Offroad and Off. In offroad conditions, it optimizes stability, traction and brake control, and activates the standard hill descent control system. In addition, drivers can select three levels of deceleration recuperation: In level 0, the car coasts, in level 1, the car slightly decelerates. In level 2, which has a deceleration range of up to 0.13 g and recuperates the largest amount of energy, drivers experience a strong one-pedal feel. In manual mode, the car retains the previously selected recuperation level.

Article source: www.audi-mediacenter.com