Toyota’s Continued Work on In-Wheel Electric Motors
Introduction:
Toyota has recently filed a patent application for in-wheel electric motors, indicating that the automaker is still actively pursuing this technology. The patent application, published by the United States Patent and Trademark Office (USPTO) on Jul. 18, 2024, was originally filed by Toyota on Oct. 30, 2023. This patent focuses on a gear-case design that utilizes two helical gears and thrust bearings, allowing the gear case to withstand thrust loads on the gears with minimal weight increase.
In-Wheel Motors and Unsprung Mass:
One of the main challenges associated with in-wheel motors is the increase in unsprung mass, which refers to mass not supported by the suspension system. In-wheel motors attached to the wheel hubs can contribute to excessive unsprung mass, making tuning for ride and handling more difficult. Toyota’s focus on minimizing the weight of the gear case is aimed at reducing unsprung mass and addressing this issue.
Toyota’s In-House In-Wheel Motor Program:
Toyota has a history of exploring in-wheel motors as an efficiency and packaging choice. The automaker first highlighted in-wheel motors as a potential solution over 15 years ago and even indicated that its iQ EV might feature them. Although the iQ EV ultimately used a standard inboard motor setup, Toyota has continued to tease in-wheel motors on concepts such as the lunar Cruiser.
Current Trends in In-Wheel Motor Technology:
In-wheel motors are gradually making their way into passenger vehicles, with companies like Aptera incorporating them into super-efficient electric 3-wheelers. However, questions remain regarding the durability and safety of in-wheel motor designs. Other automakers, such as Hyundai, are exploring alternative approaches that position the in-wheel motor design close to the wheels but not within them.
Future Prospects and Challenges:
As Toyota continues to pursue in-wheel motor technology, the automotive industry is likely to see advancements in efficiency, performance, and packaging. However, the integration of in-wheel motors into mass-produced vehicles presents challenges related to durability, safety, and overall effectiveness. Through ongoing research and development, automakers like Toyota are working towards overcoming these obstacles and bringing in-wheel motors closer to commercialization.