Comments on: Vocis is road testing a multi-speed EV transmission

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By: greg45

greg45 — Sat, 21 Jul 2012 19:20:32 +0000

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By: tapra1

tapra1 — Thu, 15 Mar 2012 12:11:37 +0000

– come to production, they stand to improve any EV’s range and/or speed capability. Smaller batteries could be used, Tech Blog

By: reinCARnate

reinCARnate — Wed, 07 Mar 2012 17:32:38 +0000

That's not necessarily true. Lots of people who convert there cars maintain the original manual transmission. It works fine. Of course, if you don't adjust your shifting habits you can burn the clutch faster, but then again, you don't have to shift quite as much.

I think large industries tend to follow one line of thought rather than multiple ideas. They have decided to make EVs feel like automatics under the assumption that most people don't like shifting.

By: DrInnovation

DrInnovation — Sat, 10 Sep 2011 23:26:12 +0000

The Volt gas engine does not come on at an y particular speed. It comes on when they battery charge becomes to low.

The volt has a sun gear that the primary EV traction motor and it can take the car as fast as the limiter allows (100mph). There is a second electric motor(and/or generator). The second motor can drive, in electric mode, the ring of the planetary gear (which can be clutched by the computer). This provides more EV efficiency at higher speeds.

The ICE (gas) engine only is used when the buffer is to low, which is called charge sustaining mode (CS-mode). The ICE is clutched to the the second "generator" motor to produce electric to drive the Traction EV motor (then it looks like 1-motor series hookup). When in CS mode its only 1-motor electric drive with lots of toque. When in high speed (low HP demand really), and in CS-mode, the ICE can clutch to the generator motor and the generator motor is clutched into to the ring of the planetary, providing 10-15% more efficiency. This improves MPG in range extended mode (i.e. a more efficient use of the ICE engine.

By: Dom

Dom — Fri, 09 Sep 2011 17:30:52 +0000

Quote "That is the one minor downside to eventually getting an EV, I'll miss the stick. I've always had a stick. They are fun to drive, they keep me engaged, I feel that I have more control. Even is EVs get multiple gears, there won't be a clutch or stick."

Amen to that. But is there a technical reason a transmission in an EV can't have a clutch and stick? Or does it have more to do with the fact that most Americans never developed the necessary coordination to drive a manual transmission car?

By: theflew

theflew — Thu, 08 Sep 2011 01:41:22 +0000

The Volt can go from 1 – 100 mph using battery alone. Only when the battery is depleted and the car is generating electricity and in low torque demands (i.e. cruising at ~72 mph) is the engine used along with the main traction motor. One of the reasons it’s used is because the Volts main traction motor and the second motor/generator are used basically as a CVT when cruising for efficiency.

When the battery is depleted and the ICE is turning the motor/generator (second motor) to generate electricity for the main traction motor, if traveling at cruising speed once again the second motor/generator is clutched in (just happens to be clutch to the ICE as well). But, if the battery is depleted and you stepped on the accelerator the Volt will still go from 1 – 100 using just the main traction motor because the ICE isn’t used for high torque since the ICE is only ~ 80 hp.

Basically the Volt is an EV, serial hybrid and parallel hybrid. It can go from 1 – 100 mph in EV and serial hybrid modes. Parallel mode is reserved for constant speeds at higher speeds when the main traction motor is less efficient and there isn’t sufficient battery power to be in EV mode.

Youtube video that talks about this whole subject:
http://www.youtube.com/watch?v=IWSK8BR6LT8

By: Shines

Shines — Wed, 07 Sep 2011 19:17:51 +0000

The graph shows a single motor’s efficiency rating. I wonder if 2 electric motors – a larger one to handle acceleration and higher torque efficiently and a smaller motor to handle higher speeds more efficiently might work better than a transmission. Electric motors are so compact that the there may be weight savings by avoiding the transmission by replacing it with a smaller motor. I am not an engineer so I really wouldn’t know. I understand that there would be some kind of transmission to run the drivetrain between the two motors, bit it might be a lot simpler. Just pondering…

By: MrEnergyCzar

MrEnergyCzar — Tue, 06 Sep 2011 19:31:56 +0000

Is this why the gas engine goes on when driving the Volt above 72 mph? The battery is less efficient at higher speeds?

MrEnergyCzar