electric motor tech

Hi tpfun,

Yes. The unit on the left is the Gen II drive train, with its very high torque MG2 to the right of the unit, and the silent chan and extra gears to the axle. The unit to the right is the Gen III drive train. Its not easy to see, but there is a gear set between the smaller MG2 and the PSD. This is silmilar to the Camry drive train, and other newer Hybrid drive trains.

Being a lower torque, higher RPM motor, MG2 in the Gen III Prius would use smaller permanet magnets. The transmission on a whole, is 100 pounds lighter. Which is quite a feat, considering the Gen III transmission is like 20 % more powerful.

 

The chain in the Gen II is no doubt less robust than a gear set. Wonder why it was used in the first place ?

Thanks for confirming my claim in the TC thread that the MG2 motor has been downsized to assist in the TC issue.

 

This is a false conclusion. MG2 is smaller in the Gen III, but more powerful. It actually produces more torque at the drive wheels, which would exacerbate the TC issue, not help it.

Tom

 

This is true, they did earn the "rare" moniker for a reason. However, they're not called "rare earths" for the reason you think they are. They're called that because they don't exist in large, dense deposits, but are rather spread around and mixed together with each other and other minerals. Neodymium is almost as abundant as copper, which is used in just about everything these days, given the proliferation of electronics.

That said, it's not cheap stuff, and it's not easy to get, so I'm in favor of reducing the need for it, assuming it doesn't get replaced with something worse...

 

In addition, rare earth elements are all chemically similar. This makes it difficult to separate one from the other. Until recent times, there was no commercially viable method to do this. It was indeed "rare" to get one in its pure form.

This is why rare earths are often used in an unspecified mix, such as in fireworks and pyrotechnics. For magnets, though, we need to separate them, which adds to the cost.

Tom

 

As many have said, the Prius motor is a brushless design. But what many have overlooked in the original quiestion is the life expectancy of the bearings. History has never shown a case of a failed bearing in the motors. There is one caution that many overlook: The bearings and other moving components are lubricated with the same oil used as coolant. But the system is a closed system. That is, the oil used to lubricate the hybrid components is not shared with the coolant pumped throught the system. The lubricating oil IS pumped by a pump at the rear of the transaxle and is linked to the gas engine. So, the hybrid system is only lubricated when the gas engine runs. Generally, with the on and off characteristics of the gas engine when driving, this is not a problem. But, many who boost the battery pack in an attempt to get many miles of electric driving are endangering their transaxle due to lack of proper lubrication.
I cannot speak for lubrication of the GEN3 transaxle.

 

Is ken1784 Ken@Japan still active here ?

He seems to have a Toyota connection.