On the Innovative Design of Geared-Transmissions for Hybrid Electric Vehicles with Mechanical Reverse Driving Mode

Abstract

Due to growing concern regarding global warming and its adverse environmental effects the market for conventional vehicles with internal combustion engines is in gradual decline While electric vehicles are regarded as a promising solution for future transport needs many issues remain to be resolved before they can become a commercial viability As a result hybrid electric vehicles (HEVs) which combine a traditional internal-combustion engine with one or more electric motors or a battery pack have attracted great interest in recent years This study proposes a systematic design approach for the synthesis of feasible hybrid transmissions In particular depending on the driving environment the specifications of the vehicle power sources and the desired vehicle performance promising novel designs are selected for the teeth number design The kinematic characteristics feasible mode shifts and vehicle performance (e g maximum speed acceleration time and gradeability) are analyzed Finally a computer model of the novel design is developed and simulations performed based on standard drive cycles In existing hybrid transmission systems the reverse gear is usually implemented by reversing the rotational direction of the motor and that should be improved As a result this thesis focuses on the innovative design of a hybrid transmission system with a mechanical reverse driving mode Using the proposed systematic design approach two novel designs are synthesized consisting of a simple planetary gear train a Ravigneaux planetary gear train an engine and a motor Based on the high-level evaluation results one of the designs is selected for further development and analysis It is shown that for the considered design the maximum number of teeth is equal to 72 and all of the gears satisfy the design constraints Furthermore the kinematic analysis shifting analysis and performance analysis results indicate that the proposed design results in a maximum vehicle speed of 241 km/h a 0 ~ 100 km/h acceleration time of 7 13 seconds and a gradeability of up to 49% All of the results meet the desired performances Meanwhile the SIMULINK results show that the novel design achieves a fuel consumption of 18 03 km/L in urban cycles and 20 41 km/L under highway driving conditions Notably the fuel consumption achieved by the proposed design is competitive with that of existing HEV models on the commercial market

Date of Award	2018 Jul 4
Original language	English
Supervisor	Hong-Sen Yan (Supervisor)