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Unread 30-06-2003, 15:37
Jnadke Jnadke is offline
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Quote:
Originally posted by Ianworld
A friend of mine directed me towards the Toyota prius (and i suppose other hybrid cars.) They have two inputs at varying speeds and combine them to produce one output. Unfortunatly i haven't been able to find a good source of information on the topic of their transmissions but i'm still searching. Might be good place to look for more info.
The Prius uses electric generator/motor at different stages in the drivetrain. Primarily, the gas engine exerts power into a planetary gear system. One part of the planet is connected to a generator. The other part is connected directly to the wheels. As the engine rotates, it exerts equal torque on both the wheels and the generator. As the generator produces more electricity, it exerts more torque as a reaction, thus, the engine can exert more torque on the entire system. Basically: The torque is split between the wheels and the generator.

The neat thing, however, is that the power created by the generator (when the batteries are full), is sent to a motor that is directly connected to the driveshaft that, ultimately, leads to the wheels (after the planetary gear system). So, contrary to belief, the Prius planetary gearbox does not have two inputs. Its planetary gearbox actually has one input and two outputs. The only exception to this is when it is using regenerative braking.

Quote:
Originally posted by Tytus Gerrish
But still In spite of its disadvantages it will Combine the force of two motors over a larger power arc than any ideas ive seen yet ,wich Work! but when theyre slowed down By puching Or accelarating They will not Be as efficent as My device
1. You can't get any more efficient than 100%. Traditional gearing will combine the torque while still allowing the same top speed. Do the math and you end up with the same power output as the sum of the two motors.

2. If you've learned anything from the explanation of the Prius above, you cannot exert more torque than the weakest motor (believe me, if Toyota could operate at greater than 100% efficiency, they would). Once you do, it will act as a generator. The power output of the remaining motor will be split between the wheels and the generator. The bad thing is, all the speed controllers do with this generated power is get rid of it, as heat. Basically, this limitation makes this system bad for pushing applications (when using motors with dissimilar torques).

3. Actually, I got the idea from a patent when I was surfing the internet. Technically, it's not your device. It belongs to the guy that patented it. Beyond usage for non-profit applications, you have no rights to it.
Differential electric engine with variable torque conversion
Continuously variable transmission system
Continuously variable gear drive transmission
Electric constant speed/variable speed drive/generator assembly

There's a lot of neat stuff floating around in the patent database. All of it is free range to us since we're using it not-for-profit. Sometimes when I have an idea I search there to see if there's a better idea or to see if it's feasible.

Quote:
Originally posted by Ianworld
Good thing i found this thread. I was about to try to build something like this without knowing the short comings.
Thank you. You really have to realize what the two parts independently are doing, and then piece them together. Instead of being an input, pretend it's a fixed shaft. You'll then realize that such a system does provide some benefits, but also has some quirks. Such an idea could succeed if you could develop an easy mechanism to mechanically stop the shaft and hold it in place. The Thunderchickens did so using worm gears. The bad part is that worm gears are 75% efficient at best. A more realistic estimate is 50%.
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Last edited by Jnadke : 30-06-2003 at 15:53.
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