# planetary gear reduction infinite gear ratios



## aeroscott (Jan 5, 2008)

a friend had a electric boat 36' trimaran with a twin armature 3 phase motor with planetary gear reduction ran the sun gear the other ran the ring gear ,by varying the speed of the gears infinite gear ratios were had. this system is used on the Mars rover. his was only 3 or so hp and cost about 7,000 ,it had a lot of gear noise came with a controller and bigger systems were available at much higher cost. if it could built using 2 motors on a modified planetary (bearing and chain on the ring gear) . I still like 1 or 2 motors on a standard rear end, simple .


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## aeroscott (Jan 5, 2008)

a better title would be planetary cvt.


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## xrotaryguy (Jul 26, 2007)

I liked the title 

I like the idea too. There's no reason that this could not work. You might potentially be able to buy smaller motors this way too.


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## aeroscott (Jan 5, 2008)

i am looking into the 3 phase motor controller that I found in the EVDL archives it was part of a contest on circuit cellar.com (electronics magazine) open source 100 hp continuous/300 hp peak. though I died and went to heaven. it has a feature of svm (space vector modulation) to enhance low end torque and overall harmonics thus efficiency .see toms post on diy motor controller for the outstanding progress on that front. sorry for the digression but that got me thinking of wheel motors and the need for low end torque. Now if a auto trans has a spinning ring gear planetary gear or two .These are controlled by bands, if they could be modified to be driven by another motor you could have a 2 motor system.


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## dataman19 (Oct 7, 2009)

Does not the Prius use a planetary drive to provide seamless interaction between the electric traction drive and gasoline auxiliary drive motor?
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So why is it it wouldn't work else where...
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If it works in a trimaran boat, and a prius - why not?
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Noise? Really? Can't noise be controlled by precision gear machining, and or proper sound proofing? How about the age old method of enclosing the whole drive in an enclosure and putting in gear oil. dang! I gave it away.
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Gear oil is why standard transmissions don't make a lot of noise. Don't believe it? Open it up, take out the oil, then start the car (preferably jacked up so it doesn't take off). Put the car in gear.... Do ya hear the noise?
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I thought so....
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Sorry about my callous attitude. I'm just making a point.
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I personally think that an efficient Planetary Drive system would be perfect for an EV. The problem with prototyping and brass boarding (the working final prototype) is costs. Costs to fabricate, cost to machine, and the re do expenses.
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A Planetary Drive would easily accomodate two or three motors. This would provide for seamless integration and allow you to instantly introduce or remove one or more of the motors without having to shift a gear or anything, except maybe throw a swith.
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Check this out:
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http://www.howstuffworks.com/gear7.htm
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The Three Green Drives could be motors - the center drive can be the Drive to the Drivetrain. The outer Ring can be fixed (or an ICE connected for aux drive - opps that would make it a hybrid...)
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Then either of the Motors, or all, or any combination can be powered on-off. This would provide an ulimited range on Torque (Up to the total torque of all motors), Power consumption/savings, or acceleration and cruise on flat or hilly terrain, even a varying regen capability.
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Production costs are not important (unless it will be nuclear powered).
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The problems are in the prototyping and pre-production implementation.
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But some body with a well outfitted home machine shop could readily produce a working planetary drive.
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dataman19


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