Electric motors cooled?

(OK I googled and i can find Gen 1, Gen 2, and Gen3 photos but no photos underneath a Prius C. Here is a Gen 2 example that will be right in essence but wrong in all the details)

The transaxle is cooled two ways, via coolant from the inverter coolant loop and via ATF bathing the two M/G directly. There is a small ATF oil pump that runs whenever the engine is running. (the left side with the Black oil pan and oil filter is the engine, the right side with the coolant and Automatic Transmission Fluid plugs labeled is the transaxle. The silver lump to the far left is the A/C compressor. Toward the back on each side are the axles to the front wheels. On a Gen 3, the plugs marked in green are by those axles.



Gen 3 transaxle plugs

 

While my wife is in NOLA next week, Inspecting a Coast Guard Station to be remodeled, I do not seem to be scheduled for NOLA until late March 2017.

Hogs For The Cause 2016 - New Orleans BBQ competition

I can't spend the entire trip judging BBQ and awarding Lions Club Scholarships, perhaps we will meet up.

 

I drive the Toyota Yaris Hybrid, that is the European Prius C, both cars are equipped with the same engine and transaxle, the transmission is not kept cool with a cooling water system, there is a special designed oil pump which circulates transmission oil via piping on the outside of the transmission.

The information down below explains the system

1) An oil sling type lubrication mechanism has been provided, which lubricates the gears and bearings by catching and transferring the oil released via the rotation of the final driven gear and counter driven gear. This lubrication mechanism helps optimize the discharge amount of oil from the oil pump that is driven by the engine power, contributing to the drive loss reduction.

(2) 2 oil catch tanks have been provided to temporarily store oil that is transferred from 2 channels. One that temporarily stores oil that is pumped up by the oil pump and is used to supply oil to the motor generator, and the other that temporarily stores oil that is fed by the rotation of the final driven gear and counter driven gear and is used to lubricate the compound gear unit.

(3) The oil catch tank for motor generator oil supply pumps up oil that accumulates in the transaxle case and the lower portion of the transaxle housing via the oil pump, feeding oil to the motor generator.

(4) The oil catch tank for the compound gear unit lubrication collects oil via the rotation of the final driven gear and counter driven gear, routing the oil to the lubrication holes provided in the transaxle case and transaxle housing to feed oil to the compound gear unit.

(5) By employing the oil catch tanks to supply oil to the motor generator and to lubricate the compound gear unit, the oil surface levels inside the transaxle case and transaxle housing can be regulated to the optimal level while the vehicle is driven, reducing the oil stirring loss caused by the final driven gear and counter driven gear.

 

I also don't know of an oil cooler for it on the outside from the factory? It's all internally cooled it seems?

I have seen 260f on mg2 going uphills while towing my jetski.

 

Below a description how the transmission oil circulates through the Prius C transaxle.
The only way the oil is cooled is via the air circulation around outside of the transaxle during driving.
There is no oil cooler on the outside.
The temperatures you have recorded going uphill look like the temperatures I get.
But this is not the temperature of the transmission oil.
The temperature sensor is situated at the stator coil.



6.1. MOTOR COOLING

PERFORMANCE

To improve the motor cooling performance of the new hybrid

transaxle, the motor cooling system was newly designed.

As with the P410, the heat generated by the gears and motor/

generator of the P510 is dissipated through two routes:

thermal conduction to the case based on part-to-part contact

and thermal conduction to the case via ATF. The heat

dissipation characteristics are extremely important because

they greatly affect the insulation performance of the motor

stator and the generated torque.

In the conventional motor cooling structure, the motor is

cooled by ATF pumped up by the final gear. In the P510,

cooling efficiency has been improved by supplying some of

the ATF to the motor through the pipe by the oil pump.

Figure 7 shows the motor cooling structure. ATF from the

newly designed oil pump is split into a gear lubrication path

and a motor cooling path. ATF from the motor cooling path is

provided through the outer pipe to the top of the case. ATF is

then actively dripped onto the stator and coil end through the

inner pipe, promoting heat dissipation from the stator and coil

end to the case via ATF. Thus, ATF is supplied evenly to the

coil end, and the motor/generator is cooled efficiently.

In particular, the conventional structure does not secure a

stable supply of ATF at low speeds. In contrast, as shown in

Figure 8, the P510 improves the heat dissipation of the motor

with a sufficient amount of ATF supplied at all times. In this

way, the new motor cooling system contributed to making the

motor/generator smaller by improving the cooling efficiency.

The contact between the stator and the case also provides

another heat dissipation route based on thermal conduction.

Thus, the cooling performance was improved by conducting a

large amount of heat to the case through these two thermal

conduction routes and dissipating it to the atmosphere.

Furthermore, because the cooling of the stator is intimately

 

Interesting. I wounder how hot the oil gets? So you see similar temperatures as me without towing? So the temperature is safe then on occasions?

 

I have looked up the maximum allowed temperatures for the Toyota transmission:

"The power rating of the Prius motor is limited by the permissible temperature rise of the motor

winding (170°C) =340F and the motor cooling oil (158°C)=315F

 

I wonder if the transmission has an oil temp sensor that a scan gauge can read ?

 

That would be a good temp to monitor!

 

Late to the thread but I just watched the Weber auto overview of the Prius C transaxle :

The fact that it is only cooled via transmission fluid is a bit concerning. At the very least one should probably change the transaxle fluid more frequently than other models.

 

Thanks for postings! I have searched for something like this vid years ago and now my wish came true!

As far as cooling on the P510. I tow trailers from time to time and don't see any serious temp changes when doing so. In fact my Scangauge shows temps being safe. I only see them rise over normal only when I climb mountains, then descend. On the descent, it starts to heat up more due to lack of the oil pump turning in the transmission off throttle. Once back on throttle the temps start to drop to normal.

It's worth noting that even without towing , I have seen temps go up to about 250f on MG2 under hot conditions.

As far as color of oil. I didn't notice a difference when changing at 30k miles with or without towing.

 

What should be the normal operating temperatures of the 2 motor generators of the Prius C? i think mine never goes past 100° F.

 

No prob! Weber Auto has TONS of good stuff for the curious.