Abstract
Keywords: Recuperation, braking, a flywheel, stepless transmission, fuel economy
Abstract: Perspective self-adjustable mechanical stepless transmission (MST) with inertial accumulator (IA) for kinetic energy recuperation at braking is proposed for modern hybrid vehicles. The MST is based on use of the mechanical oscillations generator, overrunning clutch and torsions, allowing to transform the mechanical energy with high efficiency (h> 0.9) in a wide range of gear ratio (i = 0.1 0.9). Such a transmission provides continuous transfer of power with a high degree of torque uniformity and possesses overall dimensions close to conventional fixed-ratio gearbox. Idea of the transmission has been implemented for the first time in the vehicle of Sensaud De Lavaud company in the beginning of 20 century.
Detailed numerical simulation of the device operation was carried out. The results of calculations show the use of the MST on the vehicle having 1800 kg weight and 90 h.p. engine power to allow the receiving of high value of a torque transformation ratio (KM=7), acceleration time up to 100 km/h for 13 s and a possibility of a long time stop-mode operation because only hysteresis friction in torsion shafts takes place in the MST. For movement at the speed exceeding 110 km/h direct drive is foreseen.
To use the MST in braking energy recuperation mode, the latter is supplemented with two dual friction clutches and the IA, representing a 15 kg weight flywheel, friction clutch and step-up and step-down drives. At the same time, besides an opportunity of stepless changes of the vehicle speed it is possible to take acceleration with the engine switched off from 0 up to 45 km/h during 12 s by means energy recuperation of the flywheel being un-twisted at braking. At urban cycle at the maximal vehicle speed up to 65 km/h the fuel consumption as well as emissions in the atmosphere decrease significantly - up to 30 %. Energy dissipation in brakes reaches only 15 % of the maximal kinetic energy of the vehicle that substantially reduces the attrition wear of wheel chocks. The flywheel weighs only 0.8 % of the vehicle weight and its maximal rotation speed is 1000 rad/s.
No means to avoid of fan losses at rotation of a flywheel are required because during a short stops (boarding - landing of passengers, a stop on a traffic light) energy losses of the flywheel are neglible low. Acceleration intensity control is carried out by change of the engine rotation frequency at joint operation with the IA, and intensity of braking - by the standard brake system working together with recuperative circuit of the MST. Basic design solutions of the transmission have been experimentally proven.