The effect of autonomous driving on rotational and linear sliding comfort systems

Autonomous driving is a trend in automotive that is rapidly picking up pace.

In May 2012, Google received the first approval of an autonomous vehicle in the U.S. for testing on public roads in the state of Nevada which pushed the boundaries of possibilities, and soon car manufacturers and entrepreneurs started to pay attention. In 2015, Audi presented the first near-production vehicles at CES in Las Vegas and now, 7 years on, a good number of concepts and close to market solutions have been presented by Tier 1s and OEMs.

We at Saint-Gobain understand that new interior comfort system design options like long tracks or swivel seats will push for new consumer expectations on the performance and user experience for a pleasurable and seamless ride. The future interior of autonomous vehicles will provide space to incorporate many additional comfort features like centre consoles (with the ability to hold screens and tablets), compartments for storage and complex folding systems such as office tables. These changes will transform how the end user uses a car and their experiences in it.

To enable these changes centre consoles, seats and panels will all need to facilitate linear and/or rotational movement so the vehicle’s interior can be adjusted. Current thinking includes seats that can move the length of the vehicle, interiors that can be transformed into office spaces with fold-away tables and seats than can lay down flat to create relaxation zones. Saint-Gobain’s SPRINGLIDE™ Spring Energised Bearing solutions have undergone extensive testing which shows that the combination of spring steel and PTFE can be designed for a consistent low friction while in a clearance free condition which permits ease of movement for comfort systems.

How do SPRINGLIDE™ Spring Energised Bearings work?

With rising customer demands for automotive comfort, it proves difficult to find bearing solutions that can deliver on all aspects of comfort like smooth adjustment feel or reduced rattle noise. For example, when the user moves a seat (whether adjusting back and forth or into a different position) the effort should be minimal with the elimination of rattle and noise to give the user confidence the seat is well-made.

Traditionally, consistently low adjustment forces require clearance between the bearing and the shaft at the expense of increasing vibration and rattle noise. SPRINGLIDE™ is a unique spring energised bearing material made up of a polymer composite layer (mainly PTFE compound) laminated to spring steel.

By using a preloaded bearing to address damping, misalignment and tolerance issues in a system assembly, SPRINGLIDE™ Spring Energised Bearings solve a number of design and manufacturing challenges at the same time. This unique technology utilises the latest technology of NORGLIDE^® Bearings and RENCOL^® Tolerance Rings and combines them into one simplified solution. The result is a bearing that controls torque, has a smooth feel without stick-slip and a reduction of irritating rattle and vibration noise. SPRINGLIDE™ can easily compensate for manufacturing tolerances and misalignments, giving you confidence that this solution will perform consistently over the lifetime of the vehicle.

Why use SPRINGLIDE™ Spring Energised Bearings?

For linear comfort features

Saint-Gobain understands the drive towards optimised comfort systems designed to make savings in space and weight. SPRINGLIDE™ Slotted Rib solution enables the development of a sliding mechanism for a centre console that reduces packaging space, weight, the number of parts and eliminates grease within the system when compared to existing solutions that are currently being used.

Utilising SPRINGLIDE™ can optimise your system design by offering more design flexibility and system functionality, allowing for longer travel potential with the adaptability to have stop positions along the length of travel, as well as compensating misalignment and controlling torque, all the while maintaining the highest quality performance over lifetime. Our innovative solutions create smoother, longer lasting, quieter sliding systems while reducing packaging requirements to provide flexibility for car interiors and meet end user expectations.

For rotational comfort features

With the increased demand for a more flexible, multi-functional car interior, complex foldable features such as office tables and tablet stations are being integrated into doors, centre consoles and armrests. However, the addition of these accessories means attention needs to be paid to their movement as this will effect user perceptions of quality. The interpretation of quality depends on how the individual accessories function when in use. Take the armrest for example; when the arm is raised and/or lowered the fluidity of movement needs to be balanced; too tight and the arm will feel heavy, bulky and may often squeak, too loose and the armrest will fall under its own weight, potentially causing NVH issues.

 

Control of Radial Torque

Extensive in-house and customer testing has shown that both RENCOL^® Tolerance Rings and SPRINGLIDE™ Spring Energised Bearings can be designed to control radial torque to requirements of   ≤ 1-6 Nm for 10,000 cycles over a temperature range of -40 °C to + 90 °C, utilising a single bearing on different shaft sizes of between 8-12 mm. Further torques can be realised by utilising two bearings or different diameter shafts.

Torque over temperature

As temperatures vary across the globe, component material needs to be able to withstand variances, this is especially true for rotational components and pivot point bearings as this will make the components expand and contract, changing the tribological characters of elements such as grease. Below is an example of SPRINGLIDE™ after cyclic testing for a rotational application. This example (Fig 2) shows that the torque does not change after completing tests that run for 600 cycles at each temperature shown below.

Fig 2. Temperature over cycles

Linear Movement

As mentioned above, the end user is expecting more from the interior of the car. As cars are evolving sliding systems are becoming more apparent and expected. Some examples are 2nd row armrests, storage solutions, cup holders, comfort systems and other accessories that rely on linear movement. Traditionally sliding systems within vehicles have used ball bearing slides that have to be greased, require additional packaging space, can be noisy and have issues with brinelling. Further, there is the potential for stick slip. Ball slider systems are restricted by design as the balls need to maintain tension and are unable to control the sliding force.

When designing a sliding system, it is important to get the balance between the required friction and the adjustment effort right. Whatever the load length and force of the system, Saint -Gobain are able to design a solution to support the requirements of the system.

Whilst using conventional systems, at the end of each stroke there is a possibility of stick slip where you need additional force to start the movement along its linear travel. With the new innovative SPRINGLIDE™ design this is eliminated, allowing for a smooth transverse feel while changing direction. Linear sliding tests have shown that by using the SPRINGLIDE™ slotted rib design, you have no drop off in sliding force over lifetime.

The new innovative SPRINGLIDE™ Spring Energised Bearings can provide the next generation of slides

Finding the solution – speak to the experts at Saint-Gobain

With the introduction of SPRINGLIDE™ Spring Energised Bearings, there is no need to choose between consistently low adjustment forces and low rattle noise. Instead, the combination of spring steel and PTFE allows SPRINGLIDE™ to be formed with unique design possibilities that can be used to replace sub-systems and hereby save space, weight and cost, creating clearance free systems with smooth and easy adjustment, every time. SPRINGLIDE™ brings a high quality and smooth feel to interior systems so drivers and passengers alike can enjoy a comfortable, seamless ride for a first-class customer experience.

Find out more about SPRINGLIDE™ by contacting us at Saint-Gobain. We’ll discuss your application with you, engineer to engineer, and find the right component.

Contact us using the Contact Us Form or email us at: makingabigdifference@saint-gobain.com.