The Masters Who Gave Life to Nissan ARIYA #04

Engineering Monster will deliver the essence of Nissan’s technology by interviewing the engineers who participated in the development of “Nissan ARIYA,” which symbolizes “Nissan Intelligent Mobility.” We will also deliver the behind-the-scenes of the development that created innovative technology and the DNA of Nissan that breathes in “Nissan ARIYA” as original content.

This time, Kenichiro Gunji, Chief Powertrain Engineer who created the all-new EV powertrain that delivers the premium driving experience that is the Nissan ARIYA's greatest appeal, will talk about the ideal driving experience he pursued with the Nissan ARIYA.

Consider the customers thoroughly and not only fulfill what is necessary, but also cut down on wastefulness. Nissan's vast accumulated knowledge of EVs made this concept possible.

Since I joined Nissan, I have been involved in hybrid system development projects. I am a rare type of engineer who has never worked on engine development while working on powertrains at a car OEM, haha. It was a great challenge for me to be in charge of a completely new premium SUV, ARIYA.

If we call it "premium model", it must accelerate quick enough as a driver expects the moment the accelerator pedal is pressed, has smooth acceleration and deceleration, quietness while driving, so on and so for.
EVs are the best at those things. It was inevitable that Nissan ARIYA would be developed as an EV.

Nissan is an EV pioneer, having pioneered the introduction of Nissan Leaf and expanded the scope of motorized driving with e-POWER. From a powertrain standpoint, I came to the conclusion that the EV powertrain should take the qualities of a premium car-responsiveness, smooth ride, and quietness to the next level.

Don't stop EVs to have a simply quiet driving. New motor developed to suppress annoying noise and vibration in all driving situations.

A major characteristic of EVs, which do not have the processes of intake, compression, explosion, and exhaust, is that they are quiet even when driving. However, when it becomes quiet, previously unnoticed sounds become audible. One of those sounds is the rotation sound of the motor. It is not suitable for a premium model to hear a bothersome sound when enjoying a pleasant drive with family or loved ones, or when driving relaxed using “ProPILOT 2.0”. Therefore, we have fundamentally reviewed the powertrain of EV and developed a new motor that uses electromagnets instead of permanent magnets.

When electricity is applied to the coils inside the motor, the permanent magnets rotate and torque (driving force) is generated. In order to move heavy objects such as cars, the permanent magnets must be enlarged to produce strong torque, but larger magnets increase resistance and the noise and vibration produced by the motor also increase. The new motor installed in “Nissan Ariya” generates a large force by flowing a large amount of current through electromagnets when the accelerator is pressed. In scenes where significant force is not required, such as cruising in the city or on highways, the current is reduced to minimize vibrations.
By changing the amount of power flowing to the electromagnets in the motor according to the driving situation, and thereby suppressing grating noise and vibration, premium quietness has been achieved.

This new motor with electromagnets does not use any rare earths. Rare earths are now in high demand worldwide, and their prices are skyrocketing. The new motor, which does not use rare earths and is manufactured at a lower cost, will greatly contribute to the spread of EVs in the future.

All units fit in a limited space.

A premium SUV must also have a spacious cabin in which customers can relax comfortably. The only way to achieve this while maintaining an overall length that is easy to maneuver is to reduce the space needed to accommodate the powertrain. In addition, in order to provide more space for the driver and front passenger, the air conditioning unit, which would normally be located in the cabin, had to be placed in the motor room, making the space for the motor even smaller. The new motor, which uses electromagnets, could be made more compact than conventional motors while maintaining high output, but this mission was a major challenge. As a result, “Nissan Ariya” incorporated the powertrain unit into a motor room that is smaller than the “Nissan Leaf” and comparable to a Kei car. When I first heard this story from CVE*, I honestly said, “Can you give me a break?” (laughs). But securing interior space is absolutely necessary to provide a premium experience for customers who drive Nissan ARIYA. From there, we repeatedly made millimeter-by-millimeter adjustments with the air-conditioning engineers, sometimes collaborating, sometimes fighting with each other, and after many exchanges of "Can't you move it one more millimeter?" We succeeded in fitting all the units into the small motor room.

I want you to drive on the highway at night, surrounded only by the sounds you want to hear.

Nissan has always bravely taken on challenges, even things that other companies wouldn't dare to do, and has introduced many technologies to the world. Since I joined the company, I have always seen the challenging spirit of senior engineers from behind. I believe that I was able to complete “Nissan ARIYA” because I inherited the DNA of those seniors who never give up.

As an engineer, I take pride in the fact that “Nissan Ariya” has become a highly refined car. I feel sorry that it will take a little more time for all of you to experience it, but when the time comes, I hope you enjoy driving while enjoying the night view of the highway and being surrounded only by the music you love or the sounds you want to hear. The overwhelmingly quiet driving experience should transcend the concept of a car and become a premium experience, like moving in a comfortable room.

CVE: Chief Vehicle Engineer, responsible for product development for various Nissan vehicles.

The article is from its original version released on 15 September 2020.