“Automatic transmissions are the choice of drivers. Manual transmissions survive only in some sports cars.”
— The market insight common in Japan and U.S. does not work somewhere else.
Where? In Europe.
While automatic transmissions prevail in Japanese and U.S. automotive markets at over 90%, merely 20% of vehicles produced in Europe come with them.
Most cars in European countries are equipped with manual transmissions.
Why? Because MTs allow drivers to select gears when they think it best to do, “making driving an enjoyable sensation.” Additional benefits include driving maneuverability, cost-effectiveness, and low fuel consumption.
With Japanese and American auto manufacturers moving less toward MT vehicles, the sales of parts for manual transmissions from Aisin was declining.
Still, there remained a huge MT market in Europe.
“Aisin may be a newbie in Europe, but if we can create manual transmissions that change existing concepts, we can dominate the market.”
That is what drove the team to come up with the auto-manual, a.k.a. automated manual, transmission, a third type of transmission that delivers the low fuel consumption of MT vehicles and driver-friendliness of AT vehicles.
With the new products we have in mind, we may be able to open up the manual transmission market of Europe, and bring a drastic sales turnaround for our clutches and accessories.....
What is an Automated Manual Transmission (AMT)?
A new transmission that adds mechanisms for automating manual clutch operation and gear shifting to a conventional manual transmission.
Right after the new AMT project kicked off, the team faced a hard choice between two control platforms:
hydraulic or motor control.
Technologies in the hydraulic automatic clutch system (ACS) developed earlier might be suitable but would make the new transmission bulky and costly.
Motor control would downsize the transmission and reduce cost, but no expertise in development was available.
At that time, the team heard an unexpected announcement from Europe—
In 1998, DaimlerChrysler released a new model under its Smart brand, with the world's first automated manual transmission with electric motor control.
That news knocked them stupid.
The members immediately analyzed the information and found it to be about a compact automated manual transmission packed with state-of-the-art technologies.
It spurred the spirit of project members.
“We’re shooting for a motored automated manual transmission, one that is more compact and cost-effective. Our challenge is going to be something totally new to us. But, once it achieves the responsiveness of a hydraulic transmission system, it will outperform DaimlerChrysler's….”
In January 1999, advanced development was started, aiming at a third variation of automotive transmission – dubbed an “Automated Manual Transmission” – that would integrate the fuel efficiency of MTs and convenience of ATs.
“The biggest challenge is how to downsize.”
The question was reasonable enough.
Clutch discs wear and lead to load variants, as they are used for years.
In other words, increasingly more force is needed for clutch operation.
In a typical manual transmission, the driver engages/disengages the clutch according to the response of the clutch pedal as shown in the figure below.
An electric-motor-equipped AMT does not allow manual "control" that drivers perform naturally. The motor must be capable of engaging/disengaging the clutch when the clutch disc is most worn.
If the motor performs poorly, the force will come up short as the wear advances, possibly causing the clutch not to engage/disengage.
However, a motor with the capacity designed for a worn disc could be bulky and waste generated power.
How could the team best solve this problem?
They came up with a "load controller" that would allow stable clutch operations with a small motor.
Located inside the clutch cover, the device was designed to maintain load variants within a certain safe range.
Therefore, a large motor would not be required.
“All right. Now, we have to come up with a way to keep loads constant....”
“Here's another thing. How could we know the degree of wear in the disc?”
These newly raised challenges kept the project team members busy, looking for ways to design a load control cover (LCC).
How a Clutch Works
The clutch releases the engine from the wheels when the gears are changed.
The team explored ways to maintain load variants within a constant range.
Meetings were held one after another to look for the best answer.
Though, a clue did not come quickly.
Hundreds of memos were piled up on desks....
Everyone was a bit frustrated. But, then, in the middle of one of those meetings, someone was clicking a retractable pen again and again when, out of the blue, a voice was heard, "That might be what we need.”
No one else understood what he was talking about, but he continued,
“The ratchet, I mean, the clicking mechanism of the pen is the solution we have been looking for.”
His idea was applying the ratchet, like the one in retractable pens, to a load controller.
A retractable pen comes with a quick, retractable button for sliding the point in and out. A simple ratchet mechanism employs the combination of a spring and the repeated locking, fixing and release of angled teeth, to push the ballpoint tip into place outside of the casing.
A click on the button slides the tip out, and the tooth locks it.
Another click releases the tooth and the spring pulls the tip back into the casing.
“We can apply the force of the clicking, the locking by the teeth, and sliding movement of the spring.”
As shown in the figure below, using the mechanism of the rack and pinion engagement slides the pinion gear, according to the wear in the clutch disc, so that load variants are kept within a constant range.
Already in their mind, a prototype was within striking distance.
How a Load Controller Works
The pinion engaging teeth on the rack slide depending on the wear in the clutch disc, ensuring that the magnitude of load (↓) remains the same.