Protection against collision for drivers A steering system for better safety Protection against collision for drivers A steering system for better safety

The Spirit of Monozukuri—4 The Spirit of Monozukuri—4
The Story Behind the Development of the Electric Power Steering Column The Story Behind the Development of the Electric Power Steering Column
the Electric Power Steering

Aisin Releases the First Power Tilt & Power Telescopic Steering Column for Steering Wheel Positioning Aisin Releases the First Power Tilt & Power Telescopic Steering Column for Steering Wheel Positioning

It is important to adopt a healthy, alert sitting posture while driving with the steering wheel of your car properly positioned.
Driving can be a tense, unrelenting task that can place significant stress on your back and neck, leading to pain and potential injury in the event of a car accident.
As different drivers have different physiques, it is necessary to adjust the angle and distance of the steering column for a better driving position.
What allows the adjustments? The tilt and telescopic mechanismsof the steering column. (See the figure below.)

The steering column is a device for realizing the best driving position. It also transmits the steering wheel operation to the parts that turn the wheels of the vehicle and protects drivers by absorbing impact in the event of a collision. Some steering columns lock the steering wheel when the car is parked.
Today, the steering column is an automotive component that contributes to a small profile of the vehicle, driver comfort, and driving safety.

Back in 1985, Aisin Seiki took the initiative to release the world's first power steering column.
It was the first mass-produced power steering column with electric tilting and telescopic mechanisms for adjusting the steering wheel angle in the vertical direction and the forward-backward distance.

Steering Column—Tilt & Telescopic Mechanisms

  • Tilt mechanism: Allows vertical adjustment of the steering wheel angle.
  • Telescopic mechanism: Allows forward or backward adjustment of the steering wheel position.
Tilt mechanism and Telescopic mechanism Tilt mechanism and Telescopic mechanism

A Once-in-a-lifetime Opportunity Goal: The World’s Best Electric Power Steering Column A Once-in-a-lifetime Opportunity Goal: The World’s Best Electric Power Steering Column

It is often the case that a front-runner faces more challenges than the rest do.
At the same time, Toyota, the biggest customer to which Aisin supplied automotive parts, designed and manufactured their power steering columns in-house.
For more than a decade, Aisin and Toyota competed head-to-head selling power steering columns.

In the fall of 1998, one of the news headlines caught an eye. It was about the EU vehicle safety regulations requiring more stringent requirements for impact protection of car drivers to include knee impact in addition to existing frontal impact.

In addition to the impact-absorbing mechanism to prevent the steering shaft from injuring the driver, it was envisioned that the requirements for knee impact prevention would increase the importance of the safety mechanism in steering columns.

“This is like a once-in-a-lifetime opportunity.”
The announcement was welcomed by all those who plan, design, and sell power steering columns to edge out threatening competitors.

“We're gonna create an innovative power column. May the new product we give birth to be a blockbuster and robust pillar of our drivetrain business.”

The goal was the world's best electric power steering column. The project was kicked off.

How Is the Position of a Power Steering Wheel Adjusted?

Two motors, for tilt and telescopic mechanisms, adjust the positions of the steering wheel, i.e., vertical and forward/backward.

How Is the Position of a Power Steering Wheel Adjusted? How Is the Position of a Power Steering Wheel Adjusted?

“Toyota and Aisin Should Form a Power Alliance to Create a Steering Column That Is Second to None.” “Toyota and Aisin Should Form a Power Alliance to Create a Steering Column That Is Second to None.”

“We want to pass up Toyota.”
Taking the lead, ahead of Toyota's team, was another goal the project set.

All members worked to have the first draft of engineering drawings done. The team visited Toyota Motor with a package of finished drawings.
It was turned down.
“The protruding part is a negative factor to the required knee protection. I don't think this design will satisfy the requirements.”
That was the response for the first draft.

There was another challenge. An air-bag absorbs the primary shock to the driver in a collision or impact. An impact-absorbing steering column relieves the impact of a collision by detaching rapidly from its bracket.
A detached column can interfere with steering assembly parts, increasing the impact to the driver's body.
A steering column had to be designed to come apart from the assembly with no interference with other parts, while maintaining the room required to ensure the safety of the driver. And, that was not an easy task.

In November 1998, not long after the project kicked off, the team was contacted by an executive at Toyota Motor.

He said, “We are partners, yet, fiercely competing on very similar products. That's not productive for either of us. Why not collaborate? I believe a Toyota-Aisin alliance would be the best choice to create a power steering column that is second to none.”
That was a message to end the competing relationship, save time and resources, and accelerate the pace of the development.
The Aisin-designed steering column became the choice of joint development.

Designers and engineers at the two companies who long had been rivals started to work together.

Crash Tests One after Another to Determine Dimensions on the Millimeter-Level Crash Tests One after Another to Determine Dimensions on the Millimeter-Level

The question was how to avoid interference between parts in a collision.
What the team needed was analytical data on the behaviors of the column and other parts in a collision.
The project members spent months at Toyota Motor.
Crash tests were performed one after another to monitor how steering shaft parts behave upon a collision and to find out a way to avoid interference.
Car collisions can be described as head-on, side, offset, and more. There seemed to be no end for data acquisition and analysis.

Then, in April 1999, tougher requirements were added.A minimum of 40 mm clearance on the lower side in the column housing (See in the figure below) for knee protection. That was the first requirement added.

Another one was to secure a large enough stroke of the steering column to allow the brake pedal to come inward upon the impact of a collision (See in the figure).

It was a tall order to meet these requirements.
The former would require a clearance 150% larger than those needed conventionally.

To mount the product in a narrow place, extra space was needed.
Design discussions often heated up over whether to allow millimeter increases or decreases in dimensions. Drawings were gradually perfected.

Collision Safety Requirements

A buffer clearance beneath the steering column was the requirement for driver feet protection in a collision.