Evaluation of a fuel-efficient urban delivery vehicle

A novel, fuel-efficient, articulated urban delivery vehicle is developed and tested. The vehicle has a path-following steering system on the semitrailer which improves its manoeuvrability in narrow city streets. This enables the payload to be increased from 39.4m3 of freight on a conventional rigid delivery vehicle to 84.2m3 on this articulated counterpart: leading directly to up to 33% fuel saving per unit of freight task. The vehicle is also equipped with a hydraulic regenerative braking system which stores energy in hydraulic accumulators during braking events and releases this energy back to accelerate the vehicle in subsequent motion. The design of this system and the field testing programme are described. The experimental tests are used to determine hydraulic losses and to validate a mathematical model of the vehicle and regenerative braking system. Finally, the validated mathematical model is used to perform a parametric study for the vehicle operating on various standard driving cycles. It is found that operating the regenerative braking system with engine stop-start and optimized accumulator pre-charge pressures can reduce fuel consumption by 9 to 18% compared with the baseline vehicle, depending on the drive cycle. When combined with the performance improvements due to the trailer steering system and additional payload, this gives an overall reduction in fuel consumption of 35-42%.