Sit, tilt, fold

Multifunctional concepts for vehicle interiors have been high on the agenda for about 15 years now. Rear seats need to separate, slide and fold down as required. However, manual controls have their limits when they require users to pull three different straps in a particular order. It’s easier with electronics.
 
Three whining children, a crate of mineral water in one hand, and a packet of nappies in the other – it would be impossible to open the door if it weren’t for the keyless entry function. Now you just need to pull the three straps on the rear seat to fold part of it out of the way and make more luggage space. But at this point, if not before, manual controls reach their limits, since they require the user not only to have two hands free, but also to possess a certain level of knowledge. If you pull the straps in the wrong order, for instance, the back rest might fall onto the seat before it is folded away, making any further fold functions impossible.

Seat specialist Gregor Kröner is therefore thinking one step ahead. He plans to combine the keyless entry function with vehicle interior configuration. “This is the only way to achieve real utility value,” says Kröner, Head of Advanced Development for Seat Systems at Brose, describing how people will be able to load their cars easily:
 
A capacitive sensor under the bumper reacts to a movement of the foot. This information triggers various mechanisms within the vehicle. First the liftgate opens. Shortly afterwards, an electric motor lowers the seat base on one side of the rear seat, causing part of the backrest to fold down and create a flat luggage surface. The driver can then load luggage easily without having to put it down first. The rear seat on the other side remains in place because people still need to be able to sit in the back. “This process can be programmed in any number of combinations,” says Kröner, who can imagine lots of other functions. “We could have a remote key control with two or three buttons. The driver would be able to pre-program various vehicle interior configurations on it and activate them as and when required.”

Brose first presented an electronically controlled rear seat in an SUV concept car at the IAA 2007. The various segments of the modular seat structure can be adjusted at the press of a button. The buttons control the slide adjustment, the backrest tilt and the headrest – the same as in a front seat. At the same time, the seat can be folded up completely to enlarge the luggage space if required.

Two years later, Brose presented a further development of its rear seat concept at the IAA 2009. The aim was for the vehicle – another SUV – to be no heavier than a car with conventional mechanical adjusters, despite the addition of four electric motors to lower the seat pan and adjust the headrests.
 
Kröner actually exceeded this target: “The electronic solution is significantly lighter than the manual rear seat systems on the market,” he emphasizes. On reflection, the weight saving is logical because the new four-pole electric motors with rare-earth magnets are much smaller and lighter than the earlier versions. A single motor for the seat slide adjustment weighs around 250 g. Then there are the drive systems and seat rails, which were originally developed for the front seats. The weight of these has been included in the specifications for years. “The concept is mature and has been produced millions of times for front seats,” comments Kröner. To demonstrate this, he slots a slide adjustment mechanism and drive into a seat rail (bottom photo). The component also fits the rear seat system. Kröner sees this as an important milestone in the automation of rear seat systems: “A new seat rail means high development costs, making it the most expensive component in the seat structure.” The development costs are frequently in excess of ten million euros. He therefore takes standard components from the front seat kit and uses them in the rear seat unit.

Kröner and his department have made a total of four sub-assemblies that they want to deploy across all seat lines and customers. In addition to the drive technology and seat rails, the sub-assemblies include the safety-related fittings and locking mechanisms. Brose is currently adapting these to the specific requirements of the rear seat systems. This is another area in which Kröner is going for standardization. “It has just been completed for the front seat. Now the first components are being used in rear seat systems.” This ensures good economies of scale for the car manufacturers and provides a cost-effective answer to drivers’ increasing demands in the area of vehicle interiors.

“It is only a matter of time before rear seat systems are controlled fully electronically because the utility value of a vehicle is increasingly determined by the functionality of the vehicle interior. Flexible configuration of the vehicle interior is now just as important as comfort and safety in the back. The combination of electrical adjustment components, control electronics and sensor technology makes it possible to meet all the requirements pertaining to luggage space and comfortable seating and, ideally, even reduce the weight in the process,” explains Kröner. He does not say whether the new systems will need 14 motors like some of the luxury front seats.

Article published in Automobil Industrie 6/2010