MG1 and MG2 temps too high?

My apologies. I'd always assumed that the inverter cooling loop included the MG1 and MG2.

 

No problem as that has been the case for all Prius except the Prius c. It remains an area I am curious about.

What I would love to see would be a set of data where someone records ICE, MG1 and MG2 temperatures including about a 30 minute drive at different highway speeds. This will give us some field data about how effective the new cooling technique works in practice.

Bob Wilson

 

The C uses an oil spray bar to cool the motors. If you watch on a scan tool, you'll see MG temp drop when the ICE kicks in; the transmission oil pump runs, and this sprays oil on to the ends of the rotors. This is a very efficient method of cooling, and is used in lots of racing gear boxes, from race cars to race boat outdrives.

 

You probably meant the 'stators' as the PM rotors probably don't get that hot. I wonder if the engine of the Prius c will kick on to provide cooling for a hot transaxle? . . . just idle speculation.

I am surprised Toyota did not go with an electric oil pump in the transaxle. They already have an electric water pump, inverter pump, heater core pump, electric AC compressor, and power steering. Perhaps in the next Prius family of power plants. <GRINS>

Of course if they do electric in the transaxle, replace that dang engine oil pump with an electric too!

Bob Wilson

 

Forgive me if I am getting this wrong, but from what I read the "C" transmission is only cooled by air passing over it's case.

Would it not be prudent to fit an external oil cooler in hot climates or areas where hill/mountain climbing is encountered. This must improve the likely longevity of the MG's and bearings. The fill and drain points should make good flow and return access.

John (Britprius)

 

Yes. The stators... lost my mind there... sorry.

 

The cooling oil for the MG's passes through an external tube. I have yet to get into a 510 gear box, but if this tube is removable without tearing down the transmission, it'd be the easiest. You could also pull from the drain and return to the fill, but you'd have to run an expensive electric oil pump from the likes of Tilton, that would be suited to hot oil.

 

Can do. This weekend, maybe. Lower speeds, because it's Japan, but steep elevation changes.

 

This is one of those cases where I wish someone would do a series of oil tests:

1. 5,000 miles - initial flush should include particle inspection to identify any left over debris
2. 15-30,000 miles - provides a second data point to look at viscosity changes as well as wear material
3. 15-30,000 miles - a third data point
4. xx,000 miles - testing the projected viscosity change trying to find the 15% viscosity change point

I'm doing this for my wife's 2010 Prius using R&G Labs of Tampa FL. It runs about $20 including a 40C and 100C viscosity test. The particle inspect was extra, $40-50(?) but gave insights to what was left over. I reuse, dry, water bottles, the small ones, to make sure they have enough.

Bob Wilson

 

Any testing is better than none. Just when I last checked, Blackstone does not do the 40C/100C viscosity test which gives a truer picture of the oil health. Still, any testing is better than none.

Thanks,
Bob Wilson

 

I actually was going to switch my transmission oil over to a synthetic at 10,000 miles. This is something I've done with previous cars with some success, but never anything like a Prius. Is there something magic about 5,000 miles, or is it just an arbitrary point? I have an Amsoil preferred membership until next December and I was just going to use Amsoil's stuff, now that Amsoil has OK'd it.

 

Feel free to review my earlier work:
Prius Type T Oil Analysis

Bob Wilson

 

WearCheck, out of Cary, NC, does particle analysis with their MOB 2 kits. They do kinematic viscosity checks at 40 and 100 deg C also if you ask for it when you send the sample in. They're a pretty good lab.

 

Hi all, I have a C3. From the info I've gathered from you guys. It seems I can track my transmission fluid temp by monitoring the MG1 temp, MG2 temp, MG1 inverter temp and MG2 inverter temp. Since they are cooled by transmission fluid. (I would think they would all be around the same temp).
I programmed them into my scan gauge and will test the temps this week.
I'm still confused on how the transmission fluid is cooled. Can anyone explain it in a simple way?
Thanks
Dan

 

Via the case. Convective cooling by air from the lower bumper air inlet and radiant cooling from the hot surfaces. There is no oil coolant radiator or loop.

Bob Wilson

 

OK thanks,

So lets just say, I use my Prius C as a taxi in Miami FL, it's summer, it's hot and humid and the sun is shining bright.
My customers want me to run the A/C. So this will keep the ICE running constantly. Do you think the ATF would be over the 175 degree temp it was meant to run at.
Thanks for your input.
Also what do you think about monitoring the (MG1 temp, MG2 temp, MG1 inverter temp and MG2 inverter temp), do you think this would be a good indication of ATF temp?
Thanks Bob

 

First, a correction: The engine doesn't drive the AC compressor so it doesn't run continuously just because the AC is on.
Assuming you're not climbing long grades or repeatedly accelerating rapidly I wouldn't think that the transaxle would get very hot. Hot weather obviously translates to hot underhood area but using the AC might actually help your situation since the fan(s) for the condenser will circulate more air through the area.
I would think that the items you've mentioned would be good ones to monitor.

 

Yeah that's true, the ICE wouldn't run constantly be it would run more often to charge the battery which runs the A/C.
Thanks for the info.

 

This is a 70 km drive. The engine is already fully warmed up before starting out. 1/3 on an expressway at about 90-100 km/hr, followed by 2/3 on city streets in pretty much stop and go traffic. Ambient temp is around 70F. (Fr) is MG2 and it's inverter.

Max temps for MG1/2 reached 80 and 85 degrees, respectively. These temps were not attained while cruising at high speed, but while driving on electric power in city traffic. As soon as the ICE comes on, the temps drop substantially, as seen by the current values of 70 and 74 degrees at the time of capture.

Interesting that the inverters stay pretty cool, even in the hot engine compartment.