This is exciting, Chris tweeted today;
"Check out the inside of the small tesla drive unit. We got the gear box apart and now offer an ATB limited slip differential replacement. Get in contact today to purchase yours be one of the first in the world! "
Nice job Chris! We are very happy with the Quaife unit in our Tesla Cobra EV race car. We can lay down two perfectly matched black strips from a standing start (hillclimb) or put the power down quickly coming out of turns on road race courses.
We haven't had much success in cooling the large Model S motor yet, so we may end up running dual motors at some point in the future and will definitely be a customer for one of your units. Splitting the power between 2 motors should help the cooling situation.
The images appear to show both front and rear drive units, which are reversed left-to-right relative to each other (because the front motor is on the car's right hand side, but the rear motor is on the left hand side). The first one (from the Tweet) would be a front unit; in the second photo it would be a rear unit on the left and a front unit on the right. Correct?
In both cases, there appears to be a pump, driven by the ring gear, in the bottom of each case. The rear unit also appears to have a fluid pipe connecting to passages in the case at the hose from the pump and to the motor bearing area. Are these lubricant pumps? Am I correct in assuming that they only function appropriately for continuous operation in the normal forward driving direction of rotation?
Thanks Chris.Yep your correct that is a front and a rear.
The pump sends oil into the motor housing though the heat sink that is liquid cooled. So all the windings and bearing are submerged in oil.
Exactly. Localized nucleate boiling is a major factor that makes water a far superior coolant.Thanks Chris.
So the liquid-cooled motor is actually motor -> oil -> water cooled... the stator's heat is transferred first to the gear oil, then from the oil to the (water-glycol) coolant? That would make that little pump in the gearbox critical to motor cooling, and might explain some of the difficulty with cooling the motor under sustained high load.
For those not so familiar with thermodynamics: oil is a poor coolant (compared to water) because it has a low heat capacity, which means that for a given mass of oil and amount of heat, the temperature rise to absorb that heat is high. Oil is only used for cooling when water won't work (such as in a transformer) or when there is oil there anyway and high cooling performance is not needed.
I just don't see that helping - water is about twice the heat capacity of oil so you would be better just flowing the oil faster than sticking tubes down the holes and restricting the flowCould there be a way to run a small aluminum tube with turbulators filled with water coolant through the rotor in order to cool the oil while it is still in the rotor? [IMG said:http://www.usa.brauntechnologies.com/enhancement-devices/wrapped-cores[/IMG]
A great potential improvement, but the oil loop is a still a critical part of the chain. Changing the heat exchanger does not change the heat transfer from motor to oil, except by lowering the cold-side oil temperature.If more cooling is required for the motor side I would just fit a larger heat exchanger as you can unbolt it very easily
As long as there is space in the case, it looks pretty easy to T the lines for an electric pump in parallel with the mechanical, no?If the oil loop's cooling capacity is inadequate for high-performance use, an electric oil pump replacing or in parallel with the mechanical pump could be the solution.
Yes, it looks like that to me, too, but space is likely an issue and getting lines through the transmission case would not be trivial. Any external pump paralleled with the stock pump would need a check valve to avoid bypassing flow when it is not pumping (it would not be needed at high road speed).As long as there is space in the case, it looks pretty easy to T the lines for an electric pump in parallel with the mechanical, no?
Kevin and Chris,That’s amazing I will have a look on grad cad
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