Hybrid Synergy Questions

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Okki

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So here's a question for you since I couldn't find a clear answer on the Toyota website.

Does the gasoline engine in hybrid synergy drive just serve as a generator to provide a ongoing direct charge to the electric motors, or does it actually have a mechanical drive line to the wheels?

It would seem to me that the torque that the electric motors can provide would tear the mechanical drive line to shreds the first time you put your foot down (i.e. two different drive lines competing for the same wheel). The gasoline engine rapidly charging a capacitor that drops more charge into the electric motors to increase vehicle speed or hill climbing ability seems to make more sense in my mind.

Okay you engineering hippies... set me straight! :) :lol: :lookout: :frisky:

Okki
 
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Okki said:
So here's a question for you since I couldn't find a clear answer on the Toyota website.

Does the gasoline engine in hybrid synergy drive just serve as a generator to provide a ongoing direct charge to the electric motors, or does it actually have a mechanical drive line to the wheels?

It would seem to me that the torque that the electric motors can provide would tear the mechanical drive line to shreds the first time you put your foot down (i.e. two different drive lines competing for the same wheel). The gasoline engine rapidly charging a capacitor that drops more charge into the electric motors to increase vehicle speed or hill climbing ability seems to make more sense in my mind.

Okay you engineering hippies... set me straight! :) :lol: :lookout: :frisky:

Okki
Click to expand...

The ICE unit provides power to drive a generator, which through a planetary drives an electrical motor, which then drives the wheels. The planetary and electric motor function as a CVT during operation. This system is used in a LOT of places, from a Prius to the huge off highway dump trucks.

You are correct that the torque of an electric motor on start up has the ability to "break" the driveline if that power is not controlled correctly. Suffice to say though mashing the throttle in a HSD vehicle will not unlease the complete torque instaneously. An analogy would be "slipping the clutch" for a brief moment in a manual gearbox, only now they do it electrically with no clutch. A drive by wire system will insure that input device (gas pedal lol) position and time of actuation takes into account the demand and brings power up gradually (a few milliseconds is enough) to keep from overpowering any of the components. It is a very good robust system. I have worked with similar units before on a much much larger scale.

The capacitor idea is good. The KERS system on F1 cars is basically the same concept. While I do some things pretty good I stop at the ICE and mechanical or hydraulic attachments. I leave the electrons to the guys who know that stuff. I know the theory and understand the operation but the last thing I like to tell the EE's is "Hey, I need to have a 4-20ma signal that is pulse width modulated." Then they do their thing and I do mine and they provide the plug lol.
 
So Stifler's video shows the ICE directly driving the wheels, but in combination of the electric motors. This means that the combined system has to be limited to the rpm of the lowest common denominator.

From a torque and acceleration standpoint, that would likely be the gasoline engine. Which would mean that the higher torque capability of the electric motor is ignored due to electric draw concerns most likely (at least in my thinking).

If the above is true, how the heck is that a benefit? Unless the math shows that the gasoline generator cannot provide sufficient current to recharge a set of capacitors (one to charge while the other dumps power to the motor) to provide the uphill/rapid acceleration performance. Even if the math shows that, I fail to see how the engine adds any performance benefit; at best it would reduce the strain on the battery and preserve range, but that's not how it's being presented in the video.

I guess i'm surprised that there even is a direct connection between the ICE and the wheels.

Okki
 
I think the ICE connects to the axis of the electric motor via a clutch, rather than direct connecting to the front wheels.(The video looks like direct connecting to wheels)

from wiki:
800px-Hybrid_modes.gif
 
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I believe the generation 1 & 2 Prius utilize a Planetary Gear Set to manage power between Motor/Generator 1, 2, and the ICE. The gearset allowed them to do nifty things like use one Motor/Generator to charge and the other to drive the wheels, ect. I believe by the 3rd Gen they slimmed it down to a single Motor/Generator unit & a CVT style system. (I haven't looked into the specifics of the 3rd gen in a while.)

I'll see if I can snag some info on TIS for you guys sometime this week.

Those in hub wheel motors have been in research for a few years now, IIRC Volvo showed a concept vehicle back in '09-'10 I think?
 
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