Naoya Jinnai

Naoya Jinnai


Aisin's vehicle electrification projectThe driving force of eAxle development is love for people and the earth

Whenever we consider the future of people and cars, we face global-scale problems. Examples are environmental problems caused by CO2 emissions from cars, including global warming and atmospheric pollution. To solve these problems, automakers around the world are promoting the spread of electrified vehicles such as electric vehicles (EVs) and fuel cell vehicles (FCVs), which are expected to reduce CO2 emissions. Under such circumstances, the spotlight is centered on the eAxle, a next-generation drive unit. As a supplier, Aisin, which has been continuing electrification development ahead of the rest of the world since the 1980s, is now working on a major project to survive in the automobile industry, which is facing a once-in-a-century major transformation period. We interviewed the project leader, Naoya Jinnai.



  • 1. What is the eAxle, the key to vehicle electrification?
  • 2. Benefitting from experience in the development without the correct answer
  • 3. Multi-speed eAxle, overcoming weaknesses of EVs
  • 4. For the future of children

Naoya Jinnai

Development of eAxle Naoya Jinnai


1/What is eAxle, the key to vehicle electrification?

eAxle is a drive unit combining a transaxle, a motor and an inverter, which are indispensable for electrified vehicles. Aisin's eAxle is not only used in eco-friendly vehicles, but is also utilized to provide happiness and enjoyment for driving, which is, so to speak, the heart of an electrified vehicle. The development of eAxles has become a matter of urgent necessity throughout the world, and engineers are undertaking a keen development race.

The number of rivals is increasing, since electrification has significantly lowered the barriers to entering the automobile industry. Industrial machinery manufacturers and electronics manufacturers, which have been active in other industries, have proposed entering the automobile industry one after another. If conventional suppliers stop evolving, they could lose market share completely.

What is eAxle, which Aisin is working on amid these circumstances? The project leader Jinnai spoke forcefully.

"Aisin possesses the world's leading technologies for transaxle development and expertise for motor development cultivated in the hybrid vehicle components development. In addition to these, we have the pride of continuing to engage in vehicles, which affect human lives. For this reason, eAxle that we develop must the most reassuring and safest device and satisfy more people."

Major changes of the times behind eAxle development

Behind eAxle development lie serious environmental problems that we cannot avoid when considering the future of humans and vehicles, including global warming and atmospheric pollution.
While strict fuel efficiency requirements for automobiles imposed throughout the world are propelling the development of vehicles using motive power that does not emit CO2, fueled by the rapid introduction of IoT, engineering innovation in new fields called CASE (Connected, Autonomous, Shared/Services and Electric) have become full-fledged to promote electrified vehicle development.


2/Benefitting from experience in the development without the correct answer

It is not just in the last few years that Aisin started the development of electrification technologies. We launched the development in the 1980s ahead of all others, and have been applying the technologies developed to various fields, such as automatic transmissions and hybrid transmissions and their control. Armed with this experience and accomplishments, a dozen or so engineers, including Jinnai, started eAxle development in earnest in September 2016.

However, the development did not make the desired progress, for it was at times when no one knew how the world would change, and even automakers cannot predict the near future. It was never easy to create a new thing while no one knew the correct answer. Jinnai was also at a loss at times; however, he had hope.

"Each of the team members, of different ages and with diversified careers, has a strong individuality; however, all of them understood that everyone was equal in front of technology. So, I felt sure that we had made steady steps forward, even though we argued heatedly with each other."

Over a relatively short period of time, they made more than 10 advanced development units of various types and also made some trial vehicles to check performance. By reiterating hypotheses and tests in many aspects, the prototype of eAxle, which embraced the engineers' passion, was taking shape.


3/Multi-speed eAxle, overcoming weaknesses of EVs

From around 2017, collaboration among AISIN Group companies accelerated, and as a result many resources were allocated to eAxle development team.

After the organizational foundation was strengthened, they faced the problem of achieving acceleration and maximum vehicle speed at the same time, which they had been working on as the most challenging problem since the project started. This is made possible by increasing the size and output of the electric motor; however, this results in larger-than-necessary size and output, which is not a good thing considering that the mounting space on the vehicle is limited. What was necessary to solve this problem was an eAxle that allowed shifting operation.

What they paid attention to was the shock that the driver feels when shifting gears. Even if gear shifting becomes possible on EVs, unless this can be resolved, the EVs' advantage of thrilling acceleration would be lost.

"We want to make the shifting operation so smooth that the driver is unaware of it while maintaining the sensation of rapid acceleration. This is the development field in which Aisin can maximize its advantage in the fields of hardware and control, in that it has both the hardware technologies for transaxles and motors cultivated in the development of automatic transmissions and hybrid transmissions, and control technologies for them."

The development of a two-speed eAxle is still under way to allow EVs to provide such a smooth shifting operation that the driver is unaware of the gears shifting and still has an exhilarating acceleration sensation.


3/For the future of children

The automobile industry now faces a once-in-a-century major transformation period. To the question of what future lies ahead after vehicle electrification is further advanced and EVs are popularized in the future, Jinnai answered while keeping his eyes straight ahead.

"In future vehicle development, we have to be more concerned about the environment than ever. There is no goal for this. If we set a goal, evolution stops at that moment. I believe that we, as engineers, will have to continue thinking how to build a better future for our loved ones and children while continuing to do our best work."

In 2019, as a next step, Aisin, jointly with Denso, established a new company specializing in the development, calibration and sale of eAxles, named "BluE Nexus."

For a better future, eAxles will continue to evolve with the evolution of vehicles.


A drive unit combining a transaxle, a motor and an inverter. It was adopted in Toyota's new battery electric vehicle (BEV) models, the C-HR and the IZOA, and LEXUS's first commercial BEV, the LEXUS UX300e.