The company claims world’s first battery electric vehicle with a two-speed transmission and torque vectoring
Currently under test at GKN’s winter driving test programme in Arjeplog, Sweden, the drivetrain has been installed in a standard Jeep Renegade and is called GTD19. As well as torque vectoring, which effectively steers the car by putting different amounts of force through the wheels on each side of the vehicle, the system is claimed to have the potential to extend vehicle range, while providing greater acceleration, greater torque and a higher top speed.
GTD19 has an optimised “seamless shift” eTransmission and is the development of a system demonstrated last year in a Mercedes-AMG GLA 45 test vehicle. It features an electric “eTwinster” motor mounted onto the rear axle of the car, twin clutches and a mechanical “Twinster” system on the front axle, paired to the rear axle system. Twinster is GKN’s proprietary name for torque vectoring technology, and the company produces both electric and mechanical clutch systems.
The set up in GTD19 uses the electric two speed gearbox to minimise loss of power and torque while changing between the two speeds. GKN claims that Twinster technology provides swift and smooth acceleration,” while also providing greater lateral control and optimised front-wheel driving dynamics for both safety and driver satisfaction.”
The drivetrain in the test Jeep replaces the conventional vehicle’s internal combustion engine with a 120kW electric motor, providing a maximum torque of 3500Nm and vectoring of up to 2000Nm through either of the front wheels when required.
“Front-wheel drive applications of torque vectoring provide more noticeable benefits than rear- or all-wheel drive configurations, due to the relative ease of breaking traction in a front-wheel drive car,” GKN explains. The system is used generally to stabilise the car rather than to steer. It keeps the front wheels “in check” during acceleration and can correct an understeer yaw moment experienced by the driver when entering a corner at speed. Typically, front wheel drive vehicles understeer, so torque vectoring can prioritise distribution of to the wheel torque on the outer edge of a curve.
GKN claims that integrating the eDrive system on the Jeep Renegade required no major modification and included both a GKN-derived electric motor and GKN developed inverter as well as proprietary software control.