IdleStop and Go: a way to improve fuel economy

Abstract

This paper proposes a mechanical solution to save fuel by shutting down an internal combustion engine whenever it is unnecessary for propulsion, e.g., when a vehicle is waiting for traffic lights. The engine and vehicle are restarted using the energy that is stored in a flywheel. Two additional clutches are needed to enable appropriate power flow from the flywheel to the engine and vehicle. This complicates the powertrain dynamics in that the number of degrees of freedom changes due to clutch operations. Therefore, a hybrid control strategy, which is treated as a top-level controller, is introduced to deal with this finite-state mechanical system. At the lower level, the engine and clutches are controlled in a coordinated manner such that the vehicle is launched according to the driver's demands. Using a comprehensive powertrain simulation package, the proposed controller is evaluated numerically.

The Integrated Kinetic Energy Recoup Drive (i-KERD): An Optimized Powertrain for EVs, HEVs and FCEVs

“…Unlike flywheel energy storage systems (ESSs), the high speed flywheels here are for short-term storage of the kinetic energy and a high level of braking power is desirable, thus making it possible to use small and simple flywheels for widespread application in electric/hybrid vehicles and heavy machinery equipment. By matching the power output characteristics of the on-board flywheel power system with that of the vehicle/equipment, optimization of the on-board powertrain is obtained, resulting in substantial reduction of the power ratings of the electric drive systems and the amount of energy consumed on-board [3][4][5][6][7][8][9][10][11][12].…”

The mechanical hybrid vehicle: An investigation of a flywheel-based vehicular regenerative energy capture system

“…For example, for the hybrid powertrain built by the Swiss Federal Institute of Technology [14], the flywheel is used to supplement engine power output during periods of high power demand but the capture of braking energy can only be maintained for a short time. Similarly, in the hybrid transmission developed at the University of Eindhoven [15][16][17] the flywheel is used to boost power and protect the engine from low part-load efficiency operation, with only limited regenerative braking being attempted.…”