Advanced powertrain solutions BorgWarner Group

ADVANCED POWERTRAIN SOLUTIONS

The BorgWarner group is a global leader in the development of powertrain solutions. Its Traction Systems division offers a range of electronically controlled front-wheel drive (FWD) and all-wheel drive (AWD) systems for cars. Industry Europe looks at the background of this division and its range of products.

IN December 2010 the BorgWarner Group acquired the Stockholm-head quartered Traction Systems Division of Haldex Group, enabling it to expand its European customer base and range of allwheel drive solutions. From production facilities in Sweden, Mexico and Hungary, this division supplies its leading drive systems for passenger cars and crossover vehicles. Its customers include Volkswagen, Audi, Skoda, Seat, Lamborghini, Bugatti, Volvo, Land Rover, Saab and GM.

The takeover by BorgWarner in 2010 transformed Haldex Traction into Borg Warner Traction Systems and brought significant benefits to the group. The move has boosted BorgWarner’s growth in the global AWD market – Haldex’s speciality – as well as front-wheel drive (FWD) based vehicles. It has added to the group’s base of FWD/ AWD technologies and also allowed it to tap into Haldex’s well-established European customer base.

The BorgWarner Group’s global technology leadership continues apace. It is currently present in 19 countries worldwide with around 19,250 employees across 60 different sites.

A global leader

BorgWarner’s Traction Systems produces its world-renowned electronicallycontrolled four-wheel or all-wheel drive systems for cars. These systems are controllable which means they can interact with other systems in the car, making them highly functional and versatile.

The division’s traction technology was patented by the Swedish engineer Sigvard Johannsson in 1998. It began by producing intelligent all-wheel drive (AWD) systems. The first generation Haldex Limited Slip Coupling (LSC) appeared in the VW Golf 4MOTION that year.

The first generation Haldex LSC was based on a unique patented differential pump that created a hydraulic flow proportional to the difference in velocity over the coupling. The ‘stiffness’ could be varied and the torque transfer controlled with the help of a linear valve throttle activated by a stepper motor. Subsequent generations of the LSC are stilled based around the original technology but with further developments such as pre-emptive torque capacity (Gen III) or a proportional pressure-reducing valve in place of the proportional throttle (Gen IV).

Advanced AWD systems

The company’s standard AWD systems run from the Gen I model to Gen V. They are all electronically controllable all-wheel drive coupling units for cars but with

slightly different features as we move through the different generations. The Gen I includes an electronic control unit with vehicle dynamics software. It can be viewed as a hydraulic pump in which the housing and annular piston are connected to one shaft, and a piston actuator is connected to the other.

Moving on to the Gen V model, the front and rear axle of the car are connected via the wet multi-plate clutch which now makes it possible to vary the torque distribution between the two axles. The function of this generation system allows for greater functionality, as it is independent of the differential speed between the front and rear axle. This means that full locking torque is available at any given time and speed if it is needed. All of these systems can be customised to meet the needs of BorgWarner’s global automotive clients in terms of driving characteristics and traction.

Aside from the standard AWD systems, the eAWD is a new innovative concept for hybridisation and pure electrical drive. It allows for torque vectoring and the improvement of stability and vehicle dynamics. It is a system whereby AWD and hybridization are carried out in one package to reduce the fuel consumption by up to 20 per cent.

The system consists of an electric traction motor that provides both propulsion and regenerative torque to the rear wheels through a planetary gear arrangement on each side. By locating the electric drive on the secondary gear axle, the system provides the benefits of all-wheel drive with minimal changes to the vehicle layout.

A market first

In November last year (2013) BorgWarner introduced the world’s first limited slip differential designed for the front transaxle of a front-wheel drive (FWD) vehicle on the 2013 Volkswagen Golf GTI with Performance Pack. Known as front cross differential (FXD) technology, the system greatly enhances vehicle traction, handling and stability without sacrificing engine power.

Under certain driving conditions, the FXD technology’s enhanced vehicle performance approaches that of an all-wheel drive (AWD) system but costs less and offers better fuel economy. The technology uses the same electro-hydraulic actuation technology recently launched on BorgWarner’s fifth generation AWD coupling, and offers automakers a compact and easy-to-install electronic limited slip differential solution with a wide range of calibration options.

BorgWarner’s bolt-on FXD technology uses the same vehicle sensor inputs as an AWD system to generate controlled locking torque between the left and right front wheels, directing power to the wheel with the best traction even before wheels slip r spin. In some situations, such as climbing an icy hill, FXD technology also improves acceleration through more effective use of available engine power compared with brake-based traction control systems, which tend to consume engine power.

For better cornering performance, the system delivers a torque vectoring effect, shifting more power to the outer wheel to reduce inner wheel slip. To enhance vehicle stability, the system has the ability to shift more power to the inner wheel, which greatly reduces intervention from brakebased stability control systems. n