Planetary gear system

[JBee]

Well, when I brought it up earlier it was when you claimed high torque low speed motors created a lot of heat. I explained that the only time I knew of where low speed caused excessive heat is in this fan cooled type of motor. I was pointing out that unless you have this type of motor, (which EV’s most likely do not), low speed has virtually no effect on motor temperature. I believe we’ve gone full circle and now you are also claiming speed has virtually no effect on the motor temp.

Sorry I don't think it was me who brought it up. Maybe the OP?

My opinion on the matter is that technically a planetary gear is only necessary if a relatively high reduction ratio is required, which would be too cumbersome for a normal transmission to handle. In the end the final drive ratio can be achieved in various stages of the drivetrain.

From memory the Tesla Semi uses a M3 motor per wheel for drive. A total of 4. Doing a direct drive of a wheel on each side one would assume no differential, so the vehicle would have an electronic differential using the motor speed controllers instead. The top speed required for the semi is less and the tyres are bigger so they spin slower too. That makes the ratio required higher overall.

So if we assume Semi uses a 315/70 22.5 tyre with a 3.2m circumference we get about 730rpm at the wheel at Vmax 140kmh (87mph). We know that the M3 motor does 18,000 rpm. Thats about a ratio of 24.6. Fairly high for a standard gear, who knows, it might be a planetary gear already.

 

[Bill906]

Sorry I don't think it was me who brought it up. Maybe the OP?

That is the second time I confused you and the OP. I am sincerely sorry and, quite frankly, a little embarrassed.

 

[JBee]

No worries. I sometimes have problems with forum names as well, especially if they are some abstract mumbo jumbo with letters and numbers. Thats why I keep mine simple.

 

[abebarker]

To get the gearing ratios equal between the two motors another planetary gear set is added on. The planetary gears are held in fixed position. All this does is allow the motors to have the same gearing ratio. I could swear that I have seen these advertised some where. Google was shoving it my face for weeks. Now that I look for it I have trouble finding it.

 

[abebarker]

This system could be a big benefit to the boring company because of the exceptional amount of low end torque. I'm not sure if the wide rpm range would be as applicable but the torque could be put to good use.

The other configuration would be more appropriate for small spaces. If the shaft of one motor is hollow the shaft of the other can go through it (like a dual spindle jet engine) and connect to the power split device on the end.

 

[abebarker]

Look what I found. Unfortunately they don't show all the different modes in which the power split can be operated.

Now I wish I had a 3d printer. I kind of want to see how much low end torque the powerspilt will allow.


3d printed powerspilt:

 

[abebarker]

I forgot how ridiculous we were. I think resent events may be a good sign. Naturally, I would have liked to acquire a fixed dollar amount of Tesla stocks while the value of the stock was low. I guess I should be happy with what-ever.

There are many other applications for this dual motor power split technology. The spindle for milling machines could be designed with this for astonishing low end torque, especially for the size and weight. The tunnel boring machine could conceivably benefit greatly from the torque and speed control.

I do need some money to test this technique of moving matter at a distance with electric and magnetic fields. Carrying propellant is so cumbersome. I still want my flying car, even if it is more suited for space.

 

[abebarker]

Time for some silliness? My grandfather introduced me to the first principles of electricity and magnetism.

 

[abebarker]

Thank you grandpa Roy. Eh, it is fairly close. Hehe

 

[rr6013]

John K, I get you.

The amount of cost is really limited to a minimum as is the difficulty and reliability problem. The amount of performance gained will be enormous. The torque delivered at a stand still can be increased by 4 times (not sure of the actual difference in starting torque vs full speed torque for Tesla) and the efficiency goes up as well, to near maximum. The increase in weight would be the weight of a planetary gear set, if two motors are already being used. Planetary gear sets are notoriously reliable and long lasting.

It may not be necessary for all situations. A families first car may not need it. Although, it is cheap enough to be a serious consideration.

If Tesla's reputation as a leader is going to hold out into the semi truck market, or even the light truck market, then they may need to adopt this technology. It is ideal for the induction motor. (If you ask me, it almost looks like the drive train was designed to have this planetary gear dropped right in, if you replaced the round inverter with another motor.)

Interestingly, Cyber* trucks may be a fit.

But not for the first principles you assert. Traditional ring gear and pinion carrier ass’y provide power distribution enabling reduction in sprung weight.

Sprung weight becomes most important to performance. Performance in power delivery, traction, balance and quickness.

Sprung weight using carrier ass’y enables suspension geometry to rotate 90° providing for swing arm .v. A-arm as Cybertruck is engineered. Performative improvements are in power delivery, ground contact, speed and handling. Simply it would be able to maneuver, control and improve Cyber* truck’s capabilities off road, recreational and racing stability.