Sitting Up for Consumer Comfort

In markets such as the U.S. and Europe, car ownership is declining in favor of mobility-on-demand services. Such services are growing so popular, in fact, that the car-sharing fleet is on track to reach 240,000 cars worldwide by 2020, according to a study by Frost & Sullivan.

With this vehicle-sharing in mind, the quality of the mechanisms used for seat adjustment is becoming more and more important to accommodate various drivers’ needs and individual preferences.

Furthermore, good seat adjustment is crucial for road safety, giving drivers a clear view of the road ahead, while also allowing them to reach the pedals easily. With so many drivers using the car, adjusting the seat each time, the seat mechanisms have to withstand frequent adjustments, without succumbing to increased wear, tear or noise levels.

At the same time, consumers want a luxury experience when they get in their car. They will be spending hours sitting on long journeys, so their seats need to be easily adjusted to ensure comfort and good posture support, with smooth, quiet seat mechanisms that stay in position, even during bumpy rides.

There are a number of seat-adjustment elements in a modern car where things can go wrong, causing noise in the passenger cabin or failing to provide the required level of support, negatively impacting on drivers’ experience. To keep things in check, automakers are re-evaluating small parts such as structural fasteners and bearings that can make a difference in the performance of seat height, back tilt and seat-folding-adjustment mechanisms.

Both the manual seat adjusters still popular in Europe and powered mechanisms widely used in the U.S. require a lot of care during production. Both are prone to break when overstressed by aggressive use or by passengers trying to move the seat when there is an obstruction, resulting in damaged levers and gears or burned-out motors, and requiring costly repairs.

A solution automakers are finding increasingly effective in creating high-quality mechanisms is the tolerance ring. These are radially-sprung frictional fasteners that, when used in manual- and power-seat mechanisms, are capable of acting as simple mechanical slip-clutch controls.

The tolerance ring’s wavelike protrusions can be customized so it provides a perfect fit between mating components, yet is able to slip at a predetermined torque level, protecting the lever or, in the case of a power adjuster, electric motor from damage from overstressing, ensuring the long life of the mechanism without complicating the assembly process.

In addition, with up to 11 pivot points located throughout the seat, manufacturers need to ensure they do all they can to dampen vibration and reduce noise inside the cabin. Selecting the right bearings for these points is crucial to minimize friction and vibration.

Composite bearings, for example, feature a thick, lubricating liner of polytetrafluoroethylene (PTFE) that ensures a perfect fit between mating components to alleviate rattling and vibration while the car is moving for a noise-free driving experience. The composite bearings’ robust metal backing means they support the smart design of modern lightweight seat frames, as they can withstand the increased loads experienced at bearing points without compromising on mechanism performance or durability.

Automakers are evolving their vehicles all the time. Innovations still are being made to further reduce the weight of seat frames and mechanisms, while new technologies in the rear seats now allow for increased flexibility previously seen only for the driver and front passenger. In the future, we can expect to see these trends continue, as well as the introduction of new technologies, such as “one-hand-operation” adjusters to enhance convenience.

Whatever the next few years hold for the industry, choosing the right small parts will be crucial for manufacturers to meet trends and achieve the quality drivers expect.

Mirko Hundertmark is global market manager-Automotive Interior, NORGLIDE Bearings and RENCOL Tolerance Rings, at Saint-Gobain.