- Published in Vehicle Development.
Unlike the i20, the Rio has monotube dampers instead of simpler, cheaper twintubes because they offer better response and greater tuneability, Lugert says. The rear suspension packaging means that the dampers are mounted at an angle, resulting in a reduced movement ratio.
This can affect low-speed ride in particular, where wheel travel tends to be small – monotubes can develop higher damping forces than twintube designs for given piston velocities, compensating for the small strokes.
Suspension tuning was one of the greatest challenges of the programme. Not designing the system – the set-up is conventional – but because road conditions can vary so much across Europe. It’s very expensive for OEMs to develop different components for individual countries.
Lugert and his team found that UK roads are the worst. So a lot of attention was spent on getting everything to work there too. It was hard, he says, but eventually they reached a single suspension setting which was a good compromise for the whole European market.
Intense development has gone into improving the steering system too. Like most of its competitors – the Polo is unusual in that it relies on electrohydraulics for assistance – the Rio features electric power steering. Kia’s engineers did a lot of work on control algorithms with Tier One Mando to improve road feel and feedback.
“Our supplier provided new software able to realise tuning attributes available only on more expensive systems until now,” Lugert says. “In the past, we had problems in that the return-to-centre felt artificial, but this is much better now.”
But it’s not just better components and smarter code that can make a vehicle ride more smoothly and corner more quickly – better tools can help too. Vehicle dynamics simulation packages have reached a pretty high level and can reduce development times considerably. They also enable more permutations to be evaluated before any hardware is available. But Lugert says that damper models are the weak point and finds that results from simulation and those from testing are often quite different – he’d like to see improvements here.
Good working relationships with suppliers speed up development work. The engineers from the suppliers, when involved from the early stages, can make valuable contributions, Lugert says, because of their experience and in-depth system knowledge, including what’s feasible in mass-production and what’s best left as a prototype.
It’s also a good thing to get to know your colleagues in other tech centres, he says. He has learned a lot from his peers in Korea: “It’s always more helpful if you know your counterpart face-to-face instead of just by email. You can also create some common understanding and say, look, this is the behaviour I want to have or that I don’t want. It’s easier and more efficient,” he says.
Kia is expanding its model range all the time. So Lugert will be using his network more and more as his team’s workload grows. There’s always going to be pressure from the competition too, but as long as investment in Rüsselsheim keeps growing they should be able to handle it.