Rüsselsheim. It’s time to head for the ski slopes again – and in the ice and snow of winter all-wheel drive systems come into their own. However, this is only part of the story, because an intelligent all-wheel drive system can also ensure increased safety and improved driving dynamics all year round without having to make compromises in terms of everyday suitability. The best examples of this are the intelligent all-wheel drive systems fitted to the Opel Insignia Country Tourer, Opel Insignia OPC and Opel Mokka. They represent the technical pinnacle of over 100 years of all-wheel drive development within the automotive industry. Opel’s all-wheel drive systems are now so sophisticated, they can sense and adapt to changing conditions even before a critical driving situation occurs.
The development of the complex, networked drive systems in today’s Opel models has matched the pace of change seen in the digital information age. For example, at its market launch 22 years ago, the Opel Frontera, a trendsetter in the SUV segment and one of the best-selling off-road vehicles in Europe, still relied on the classic, mechanical on-demand all-wheel drive system. Now its grandchild, the Opel Mokka, controls power distribution on demand with electronic bits and bytes. This, of course, also applies to Insignia 4x4 models led by the Country Tourer. Electronics have become established as a means of ensuring the best-possible distribution of power. In this way, intelligent Opel all-wheel drive technology seamlessly joins safety systems such as ABS and ESP.
The advantages of having an on-demand control of power distribution are immense in comparison with purely mechanical systems still sometimes used today. The inherent drawbacks of such simple all-wheel drive systems – for example, twisting in the drivetrain, substantially higher fuel consumption and a reduction in driving comfort due to stronger vibrations – are almost completely eliminated by the intelligent all-wheel drive systems in today’s 4x4 Opel models. Opel systems score with a precise, on-demand power distribution which reacts in milliseconds to changing driving situations. This makes them clearly superior to other on-demand all-wheel drive systems which rely on the purely mechanical control of power distribution when wheel slip occurs. This usually happens after a noticeable time delay, which has a corresponding negative impact on driving dynamics and comfort levels.
Opel’s all-wheel drive system has an electronic, multi-disk clutch which is flange-mounted on the rear axle differential. The disks run in an oil bath and their locking effect is seamlessly adjusted in milliseconds by an integrated control module. This solution gives Opel engineers the freedom to tailor specific control strategies which optimally adjust the all-wheel drive system to meet the different requirements of various model lines, even though they share similar hardware.
In addition to technical similarities in the electronic multi-disk clutch, the all-wheel drive systems in the Opel Mokka, Opel Insignia Country Tourer and Opel Insignia OPC also share similarities in complex networking across the vehicles’ CAN bus. Data from numerous sensors is constantly exchanged between the control modules and the Opel all-wheel drive system utilizes the same driving dynamics sensors which feed information to the ABS and ESP systems. Data about yaw rate, steering angle and wheel speeds is evaluated and included in the all-wheel drive control strategy. The system also captures other driving conditions. Comprehensive networking and seamless power distribution, which is virtually delay-free, enable the Opel all-wheel drive system to function with foresight. For example, it reacts immediately to driver steering inputs and engine power measured by the throttle valve sensor, preventing wheel slip or vehicle instability before they occur. Basically, the intelligent Opel all-wheel drive system can be viewed as a form of reverse ESP: while the electronic stability program intervenes through the braking system in critical driving situations to keep the car on course, the electronically-controlled all-wheel drive system ensures ‘preventive’ vehicle stabilization before a critical situation occurs.
The differences between the all-wheel drive systems in the Opel Mokka, Insignia Country Tourer and Insignia OPC models are the result of different objectives in line with the specific requirements of each vehicle concept:
All-wheel drive in the Opel Mokka
Environmental responsibility was a top priority during development of the all-wheel drive system for the Mokka. Hardly surprising, since Opel’s sub-compact SUV has set class standards for fuel consumption and CO2 emissions. This development goal was successfully achieved with targeted parameterization of the all-wheel drive system. The Mokka’s system can seamlessly distribute power between the front and rear axle from 100:0 to 50:50, while in normal everyday use it runs as an economical front-wheel drive car. This design enabled engineers to construct very lightweight components necessary for the all-wheel drive system during the Mokka’s development. As a result, the complete all-wheel drive system, including all the necessary axle, drive and transmission components, weighs less than 65 kilograms. The all-wheel drive system is activated when the Opel Mokka is stationary to prevent wheel slip at take-off. It also engages unobtrusively in a split second as soon as the driver depresses the clutch pedal. Once up and running, all power is transferred to the front wheels and the all-wheel drive system is only engaged when driving situations require it. As with most SUVs, the Mokka’s all-wheel drive system is supported by Hill Start Assist (HSA) and Hill Descent Control (HDC). Electronic traction control also replaces the function of the axle-differential lock with automatic braking intervention.
All-wheel drive in Opel Insignia Country Tourer and Opel Insignia OPC
When developing the 4x4 variant of the Insignia, Opel engineers focused on optimizing driving dynamics. While the all-wheel drive architecture and its integration with CAN bus data is similar to that of the Mokka, an electronic limited-slip differential (eLSD) has been introduced alongside the multi-disk clutch on the rear axle. This enables power to be distributed transversely, between the rear wheels, as well as longitudinally between the axles. Optimal adaptive driving dynamics are ensured by sporty control logics and the system’s ability to transfer all drive torque to the rear axle. Together with the intelligent limited-slip differential, which also seamlessly distributes power according to the prevailing driving situation, the Opel Insignia 4x4 offers a unique experience which gives the driver best-possible vehicle control. The ESP’s control strategy has also been optimally adapted to suit the all-wheel drive system. As a result, drivers can fully exploit the enhanced driving dynamics of the 4x4 Opel Insignia, especially when 325 hp is available from the powerful OPC version. With Opel’s fast-acting all-wheel drive system, driving safety and driving fun both reach new levels.
It’s time to head for the ski slopes again – and in the ice and snow of winter all-wheel drive systems come into their own. However, this is only part of the story, because an intelligent all-wheel drive system can also ensure increased safety and improved driving dynamics all year round without having to make compromises in terms of everyday suitability ...
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