Modelling of hydraulic regenerative braking systems for heavy vehicles

Abstract

A hydraulic regenerative braking system for an articulated heavy vehicle is modelled for an idealised urban driving cycle, consisting of one stop and start from 30 mile/h, in a distance of 700 m. This model is used to guide specification of a hardware system but not to investigate brake blending methods or the torque distribution during braking. The specified system consists of a high-pressure accumulator and a low-pressure accumulator, connected by two fixed-displacement in-wheel pump–motors. One of these systems is fitted to each of the three trailer axles. This system can produce a fuel consumption saving of 21.7% over an idealised stop–start cycle. The same system was simulated over the Heavy Heavy-Duty Diesel Truck transient mode, New York City and Urban Driving Dynamometer Schedule legislative driving cycles, reducing fuel consumption by 11.2%, 17% and 11.7% respectively. Fuel consumption can be further reduced for all these cycles if engine stop–start technology is used. The potential to use the system when traversing hilly terrain was investigated, and the system was found to reduce fuel consumption by 12.6% over a V-shaped valley and by up to 5.3% over a realistic elevation profile.