Tuesday, 15 September 2015

How GKN can make the Ford Focus drift

GKN Automotive has developed a new version of its Twinster torque vectoring all-wheel drive (AWD) system for the Ford Focus RS.

Twinster uses a combination of new gearing ratios and control algorithms to over-speed the rear wheels to create a car with a high level of dynamics, feel and handling.

GKN was awarded the Ford Focus RS programme 18 months ahead of launch. In that time GKN engineers designed and integrated the Torque Vectoring Rear Drive Module (RDM), and the Power Transfer Unit (PTU) and CVJ side-shafts into the base front wheel drive platform. 

n the Ford Focus RS, the Twinster twin clutch system can apply torque to one or both wheels independently, enabling the vehicle’s dynamic torque vectoring functions across its entire speed range.

This required major reconfiguring of the system componentry to fit the packaging space available. GKN’s in-house software and calibration teams worked with Ford and its vehicle dynamics engineers to develop new control algorithms for the torque vectoring system to give the driveline four different driving modes

According to GKN Automotive president of engineering Peter Moelgg: “GKN’s AWD technologies and torque vectoring expertise are helping auto manufacturers take their cars into new territories. AWD is becoming the driveline of choice for performance cars because it’s the most effective way of putting power onto the road, from the track to the Arctic Circle, with precision, efficiency and intelligence.”

GKN Driveline vice president of Global Product Technology Dr Ray Kuczera says GKN is “the only supplier” with the expertise and capability to deliver this diverse hardware, as well as the vehicle integration through software and performance calibrations.

“To deliver torque vectoring systems of this calibre requires engineers who understand vehicle dynamics and have the ability to partner with an automaker on vehicle level attributes,” he declares. “The result of this partnership with Ford demonstrates how driveline innovation can influence vehicle dynamics and raise handling performance to a new level.”

This latest (announced) version uses new gearing ratios that deliver more torque to the rear wheels than previous applications. When AWD is engaged, Twinster is driving the rear wheels faster than the front. This over-speeding changes the way the car feels and handles.

On bends, for example, Twinster makes the vehicle turn in more sharply, responding more immediately to the driver’s inputs.

In Ford’s “drift mode”, the AWD system delivers even more torque to the rear axle, delivering enough torque to the rear wheels for the RS to achieve a controlled “drift” through corners.

Some “torque vectoring” systems use the braking system to achieve simple vectoring effects but GKN claims these can slow down the vehicle. 

According to GKN, fully dynamic torque vectoring requires an intelligent driveline that can apply increasing tractive force directly to individual wheels. This produces purer performance and feel, while also preventing excessive brake wear.

GKN Driveline’s senior director of AWD Product Technology, Edward Kwon, claims:  “AWD programmes like the Ford Focus RS are rewriting the rules for drivelines – and GKN innovations help make them possible. Our dynamic torque vectoring expertise helps create halo models that set new benchmarks for performance.  By working with GKN on the standard AWD system and the torque vectoring version, automakers can realise the best possible result for their global platform.” 

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