Abstract
As environmental regulations have been strengthened worldwide since the Paris Climate Agreement, the automobile industry is shifting its production paradigm to focus on eco-friendly vehicles such as electric vehicles and hydrogen-battery vehicles. Governments are banning fossil fuel vehicles by law and expanding the introduction of green vehicles. The energy efficiency of electric vehicles that use a limited power source called batteries depends on the driving environment. Applying a two-speed transmission to an electric vehicle can optimize average speed and performance efficiency at low speeds, and achieve maximum speed with minimal torque at high speeds. In this study, a two-speed transmission for an electric vehicle has been developed, to be used in a compact electric vehicle. This utilizes a planetary gear of a total of three pairs, made of a single module which was intended to enable two-speed. The ring gear was removed, and the carrier was used in common. When shifting, the energy used for the speed change is small, due to the use of the simple method of fixing the sun gear of each stage. Each gear was designed by calculating bending strength and surface durability, using JGMA standards, to secure stability. The safety factor of the gears used in the transmission is as follows: all gears have been verified for safety with a bending strength of 1.2 or higher and a surface pressure strength of 1.1 or higher. The design validity of the transmission was verified by calculating the gear meshing ratio and the reference efficiency of the gear. The transmission to be developed through the research results of this paper has a simple and compact structure optimized for electric vehicles, and has reduced shift shock. In addition, energy can be used more efficiently, which will help improve fuel economy and increase drive range.
Highlights
The spread of electric vehicles using environmentally friendly fuels is increasing
If an electric vehicle is heavy, there is a loss of power transmission due to the weight of the vehicle. These results show that heavy electric vehicles that are less efficient have a reduced drive range, and have batteries that need to be charged more frequently
If the weight of the vehicle is reduced by 10%, the fuel efficiency of the vehicle is improved by about 3% to 8%, the acceleration performance is improved by 8%, and the emission of environmental pollutants is reduced [13,14,15,16,17,18]
Summary
The spread of electric vehicles using environmentally friendly fuels is increasing. The success of the electric vehicle market has been accelerated, as major car manufacturers have reorganized their production around electric vehicles since the “diesel gate” in 2015, when the emission control scandal broke out [1,2,3,4]. According to the International Energy Agency, the number of electric vehicles sold in 2017 was around. 1.1 million units, an increase of 54% from the previous year, and as of 2017, the number of global electric vehicles was close to 3.1 million. 580,000 electric vehicles were sold in China in 2018, up 72% from a year earlier. China has led the global electric vehicle market, accounting for around half of the world’s sales.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
