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Comment by _yb2s | Hacker News Reader

Computer control of the transmission (and engine) is likely necessary because it is a parallel hybrid: to charge the battery and to seamlessly switch between power sources, a computer needs to control the throttle, clutch, and shifting based on long term goals like maintaining a certain charge level, and optimizing the fraction of power coming from each motor, that are invisible and orthogonal to what the rider would want for controlling the bike.

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I understand why the ICE throttle, but why the transmission ?

Regardless of which gear you're at, the control input from the driver should dictate the power output, and it is up to the control system to figure out the split based on current conditions like state of charge, setpoints etc.

What am I missing ?

For example, to shut off the gas motor without drag while seamlessly switching to EV power, the clutch has to be auto engaged. Another example is the opposite, if the battery is getting low and needs to be charged, the transmission needs to downshift to a lower gear at the same moment the drag from charging is engaged, or the bike will not have enough torque to maintain speed.

Since the transmission is not just for driving the bike, but is also the connection between the charging generator and the engine, it’s automatic control is necessary as part of managing the battery level.

Now if you had an old fashioned simple EV system like the first Honda Insight, where the electric motor and gas engine are directly connected and can’t spin independently, in that case you can have a regular manual transmission, as those vehicles did. However, they are much less efficient and versatile, and don’t have a useful EV only mode.

> Since the transmission is not just for driving the bike, but is also the connection between the charging generator and the engine, it’s automatic control is necessary as part of managing the battery level.

Is it ? The article mentions "Integrated Starter Generator (ISG), which saves weight by combining the functions of the starter motor and generator"

Also, in the "ECO-HYBRID" you have the both the options of the auto and manual shifting, with EV only mode in low speed.

I just don't understand why the motor and ICE are not connected directly but with two clutches, leaving the rest of the powertrain to the control of the user and having the ECU meddle with the throttle, clutches and power to the motor.

Anyway, thanks for the info !

Two more clutches to wear and be replaced adds weight, space, maintenance, and cost. Motorcycles are an art in throwing away assemblies that aren't necessary.

I'm confused now about the ISG also. I suspect it serves as a 12v alternator for lights, etc. and the main battery charging is done through the hybrid motor, but it's hard to tell from the limited info in the article. Further confusing is that the EV only mode is supposed to work up to "gear 4" which suggests perhaps the motor is before the transmission, in a manner similar to what you suggested with two clutches.

Good catch with the maximum gear !

I guess we will have to wait for more information.. I trust they know what they are doing :)

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