Alan Lee, Chief Technology Officer, BWI Group asks whether cost-effective switchable suspension could finally break into the volume market

Consumers are increasingly looking for driver-selectable modes, such as sport, comfort and eco, that allow greater flexibility as desired between performance and economy, or between sport and luxury, across a broader range of vehicles. The OEM’s goal is to meet this growing desire for more options and features while differentiating their vehicles and infusing them with the correct brand DNA.

Altering the suspension damping rates as part of the mode change is a key feature, but delivering this functionality at an appropriate price point remains challenging. Tier One suppliers, like BWI, are working to develop the technologies to meet these needs cost-effectively in a broad market.

Adaptive, or controlled, suspension systems such as MagneRide deliver superior ride and handling, minimizing any compromises, but they require sophisticated hardware (actuators, sensors, electronics), software (algorithms, calibration, integration with other systems), and additional vehicle development. High performance is delivered at a premium price point.

To lower prices, one approach suggested is for the chassis ride development engineers to increase hardware manufacturing volumes by standardizing the global hardware damper specification.  Regional differences in local consumer taste could then be met with nothing more than different calibrations of the control system.  With this ideal goal in mind, the task of the Tier One supplier is to deliver the desired tuning with tools and features while minimizing the part proliferation.

Currently only MagneRide, which is unique and has no valving, provides this functionality, but it is a premium product aimed at high-end vehicles. The principal cost driver is system complexity; high performance damping control requires precise and up-to-date information regarding the road and the vehicle state at each and every moment to select the correct damping force at the right time.  This high bandwidth, real-time control requires high performance from the sensors, actuators, electronics, and the multiple computations that must all operate seamlessly together.

A more effective way to reduce cost and system complexity is to change the requirements from
real-time control to a switchable two-state suspension, such as DualRide, in which a two-position piston-rod assembly provides two clearly-defined modes. Selection is by manual switch or a screen selected menu.  Our experience has shown that the two modes, typically configured with a default comfort setting and a driver-selectable sport setting, both deliver their goals without compromise to each other.

Switchable systems can also be produced with the capacity for future upgrading to enable automatic selection of either mode. This capability could mimic the behaviour of the more expensive adaptive systems but at a cost more in line with mid-market economics.

Looking ahead, New Energy Vehicles (NEVs), Autonomous Vehicles, Connectivity, and Sharing are all changing the future view and needs of the automotive world. Demands on suspension performance will continue to evolve; power consumption will have to be managed; and lighter weight suspension and chassis products will help to offset battery weight. Ultra-quiet NEVs will also require appropriately low noise levels of suspension control.

Autonomous vehicle occupants, possibly including the driver, will wish to focus on activities including reading, emails, conversations, and video conferences without distraction. To provide this level of comfort without inducing motion sickness, yet retaining the necessary authority to control the vehicle effectively in a sudden emergency, may well require the further improvements in controlled suspension capabilities.

While the simplest passive dampers will continue to dominate the lower end of the market, sophisticated, adaptive suspension systems are likely to remain predominantly in the premium sector, even allowing for a bit of ‘trickle down’ effect to mid-market vehicles. This leaves a large area of the market open for the enhanced functionality of a fully capable two-state system.  Without the cost burden of fully adaptive technology, a winning formula without compromise should result.