Pneumatically Shifted Air Suspension Loading for Improved Fuel Economy Benefits

Since the introduction of electronically controlled air suspension (ECAS) systems in the nineties, no major improvements have been made in the realm of controlling air suspensions in the heavy duty truck market. Despite the lack of improvement, a need exists for intelligently controlled air suspension systems, specifically systems which can be applied to 6x2 axle configurations in the North American market. This study outlines a concept proposal for a novel suspension control concept which encompasses traction control capabilities in addition to suspension control for improved fuel efficiency benefit. The major novelty of the concept is that, by utilizing specific axle configurations and tires, a shift in pressure from the driven to the non-driven axles may result in improvements in the overall fuel economy of the vehicle. The shift in pressure will allow ride height to be maintained while increasing fuel economy benefits if the tires used on the non-driven axles have lower rolling resistances than the tires used on the driven axles. To demonstrate the hypothesized benefits of the system, an estimate of fuel economy was derived through theoretical calculations and known data. Physical testing was conducted to verify the theoretical results. Fuel savings opportunities were identified through the calculated estimates and were further confirmed by full vehicle track tests. Tractors equipped with certain axle configurations (e.g. 6x2 axles) and tires (e.g. trailer tires on the non-driven axle) will experience a noticeable improvement in fuel economy which will ultimately lower fuel costs for operators and reduce the environmental impact of commercial vehicles.