DESIGN AND PERFORMANCE ANALYSIS OF AN IN-WHEEL HUB REDUCER

Abstract

In order to reduce the greenhouse effect caused by CO2 emissions, a lot of car manufacturers are developing battery electric vehicles (BEVs). Almost all of these vehicles have a traditional powertrain layout with the drive unit located in the car body. However, in recent years, a new technology called in-wheel motors has appeared. It significantly improves handling and manoeuvrability of vehicles but it also presents a challenge for both researchers and manufacturers. Since the motors are fitted into a limited space, they must provide high torque and high efficiency. When a reducer is used, the amount of torque needed is decreased several times, hence the overall dimensions of the motor are reduced. This paper studies a number of issues such as the basic concepts of the in-wheel hub drive systems, traction balance, preliminary gear ratio and possible design solutions for reducers used in in-wheel hub drive units. Characteristics of single-stage planetary and cycloidal reducers are analysed in detail. The results show that planetary reducers have an advantage if a lower gear ratio is needed.