Paul Darnell

Fuel Efficiency by Coasting in the Vehicle

This paper investigates the possibility of improving the fuel efficiency by decreasing the engine speed during the coasting phase of the vehicle. The proposed approach is stimulated by the fact that the engine losses increase with the engine speed. If the engine speed is retained low, the engine losses will be reduced and subsequently the tractive torque will be increased, enabling the vehicle to remain moving for longer duration while coasting. By increasing the time period of the coasting the fuel efficiency can be increased, especially travelling downhill, since it can benefit from the kinematic energy stored in the vehicle to continue coasting for a longer duration. It is already industry standard practice to cut fuel during coasting and refuel at low engine speed. The substantial difference proposed in this paper is the controlled reduction of engine speed during this phase and thus reduction in the engine losses, resulting in improved fuel economy. The simulation model is tested and the results illustrating an improvement to the fuel efficiency through the proposed method are presented. Some results of the experimental tests with a real vehicle through the proposed strategy are also presented in the paper.

Road gradient detection using Kalman filter

Accurate, real-time knowledge of the road inclination is necessary for in-car electronic systems which are related to battery recharging system, electric motor, engine and gearbox control units. When the vehicle is moving, the measurement of the slope is not straightforward. The force measured by the inclination or acceleration sensors is coupled with the force due to the vehicle acceleration. This research examines the application of Kalman filter to estimate the road inclination. Furthermore, it compares the performance of the Kalman filter approach against the acceleration discrepancy method which is currently used by some car manufactures.