Do I need to weld if using Gen3 MG2 only

[FFMan]

As the subject says, if i intend to use MG2 only on a Gen3 inverter and gearbox, do i need to weld the planetary gears ?

MG2 seems to turn ok in sine mode but I see others have welded them up, bit confused if this was a gen2 requirement only or what ?

thanks

[johu]

Just deleted all my text, Gen3 is a different beast. Look here

[MattsAwesomeStuff]

Gen 2 and Gen 3 are different, but, even after watching Dr. Kelly's teardown again, I'm still not sure what you're supposed to do. Do you weld, and what do you weld?

[johu]

It seems to me if you lock the input shaft MG1 and MG2 turn almost at the exact same speed. So no need to weld anything.
MG2 is smaller than in the Gen2 transmission so makes it's power via turning faster.

[LeonB]

But the internal oil pump is connected to the input shaft. Thus, locking it disables the pump. If you weld the PSD, then the input shaft, MG1 and MG2 rotate together.

[johu]

So no oil being pumped while the ICE is off e.g. in pure EV mode?

[Jack Bauer]

Not with gen2 or 3 as they are not really ev rated by Mr.Toyota. That said if you look at how they work (and Mr.Weber explains this) , a lot of the lube circulation is caused by the rotation of the crownwheel in the differential. I would like to caution folks who just want to run on mg2. I understand the attraction but keep in mind that one of the things that allows us to use these hybrid parts as very effective EV drive systems is the load sharing between MG1 and 2. Indeed in the Gen4 transaxle used in the PHEV Prius and others MG1 and MG2 drive the wheels.

[FFMan]

> I would like to caution folks who just want to run on mg2.

so for those of use with single motor boards, how do we approach that issue ? I guess running on MG1 only isn't an option as it's too small.

I know you can add the links to V1c and drive the MG1 power stage, but i think this is to spread the load rather than driving MG1 isn't it as MG1 would need it's own pwm/resolver function unless it's perfectly in sync (but does internal gearing prevent this ?)

[MattsAwesomeStuff]

So, people have presumably been using the Gen 3 transaxles for projects for several years now. What are those projects all doing? (Or, likewise with the solution for the Gen 2 transaxles). Dual-motor drive boards? Welding the power split? Locking the input and not worrying about the lube?

Seems like a pretty basic question. When we get an answer I'll add it to the wiki. I really want the wikis to become more of a walkthrough on doing conversions with them than just the collection of technical aspects they start out as during the earlier stages of reverse engineer and brainstorming. The Gen 2 page is more of my baby than the Gen 3, but, they share just enough in common, and just enough not in common that I need to write down what the differences are anyway :p

[Ev8]

So yes the internal gears are used for splash lubrication, oil gets pushed around the case to the top where it sits in a small reservoir and is distributed by gravity for 2 purposes, firstly it drains down over the stators for motor cooling, secondly if feeds into the back of the plates that hold the planet gears to lubricate the needle bearings, the oil pump is very much required for lubrication of all the critical motor bearings.
The design of the gen3 means that ideally you’d want to lock the input shaft so that mg1 plangent gears still function as designed and act to multiply the torque that mg1 can contribute to the drive output, this will mean mg1 will run at almost but not quite the same speed as mg2, however by locking the input shaft you are no longer driving the oil pump….. you can instead weld the planet gears in mg1 planet carrier, this will then drive the oil pump but mg1 will now rotate serveral times slower than mg2 and loose it’s torque multiplication, don’t expect much torque from mg1…… so 2 solutions neither ideal a third might be locking the input shaft and replacing the oil pump which is externally mounted with a designed plate with suitable ports and hose tails to allow the use of an external electric oil pump.

As for control you will have to use a twin motor control board as neither the above methods have both motors running at the same speed or in sync.

If planning for just running mg2 I think I would weld mg1 planet gears and remove mg1 stator so the rotor is just free spinning and along for the ride.