Gen 4 Staff Manual (In Japanese) =/ Specs/Design/Other Info

It sounds that they did the same thing to Gen3 HSD as they did in Prius C/Aqua. It is just using higher rated electric motors and bigger ICE.

Another way they could have improved efficiency by expanding ICE sweet spot. Even if maximum efficiency only gone up by 4%, if it is more usable and ECU/HSD are programmed to take advantage of it, overall impact will be higher.

 

Prius c basically has Gen2 layout. It's MG2 is low speed (6,700 rpm) but high torque (295 lbs-ft). Gen3 MG2 was high speed (10,000 rpm) but lower torque (153 lbs-ft). However, SRU reduces it's speed and multiplies torque by 2.636 to reach 403 lbs-ft torque.

But then, reduction gear ratio is different between Gen2 and Gen3. At the end, the torque is about the same at the wheels, maybe a bit higher in Gen3 for the increased weight. More details here. SRU introduced additional friction but cuts cost and weight from having a big MG2.

Prius c has innovation where the HV battery and the 12v was moved under the rear seat.

 

The maximum output of the entire system is 90kW, which is lower than that of the previous Prius (100kW). However, the driving performance of the new Prius is equivalent to that of the previous model because of the improvement of energy efficiency, the company said.​

[Specs of New Prius] Lowest Grade Features Highest Fuel Efficiency (1) - Nikkei Technology Online
[Specs of New Prius] Lowest Grade Features Highest Fuel Efficiency (2) - Nikkei Technology Online

 

No, the transaxle isn't the difference. The rule of thumb for grease-lubricated gear stages is 2% loss per stage. There's no way a transaxle is losing 20% - it would burn up the grease in no time.

 

Perhaps there is less loss in the electrical path. Inverter is more efficient, etc. Every little improvements all adds up.

 

When engines are motors are rated, they are rated for output, not input. Therefore, efficiency gains will alter how much gas or electricity they consume to produce their output, but they won't alter the output rating at all.

 

This is probably bad translation from techno to jorno mambo-jambo.

What engineers probably meant that the efficiency "sweet spot" and overall output of the system at sub-maximum power improved, so overall car is as fast or faster even with reduced max output.

There are numerous examples in automotive world where the same car had low end torque increased at expense of reduced peak power, and it made car/motorcycle faster.

 

AFAIK, Prius c's powertrain is more like a mini-Gen 3 than a simply cost-down Gen 2.
Prius c's transaxle system P510 has the same compound gear unit layout as Gen 3's P410, not as the Gen 2's P112 chain drive type.
And Prius c's MG2 is Max. 13000 rpm / 124.6 lb-ft, while Gen 3 MG2 is 13500 rpm / 152.6 lb-ft. (Reference: SAE 2012-01-1017)

TMC did mention achieving a higher EGR ratio and a lower vehicle center of gravity in that SAE paper too.
Sounds familiar? It looks like Prius c do share some features with the new Gen 4.

 

I didn't mean 20% loss.
And if you take the whole hybrid transaxle system including PCU into account,
ICE->MG1->PCU->MG2->reduction gear->compound gear->counter gear->differential gear
HV battery->PCU->MG2->reduction gear->compound gear->counter gear->differential gear
ICE->compound gear->counter gear->differential gear
give each step a 98% efficiency
and note that HV battery is limited to 22kW
you can get a bit more than 80kW on the drive wheels finally

Anyway, I actually agreed with you there:

just replace 122kW with a lower figure could be better?

 

I'd need to get a better look but I swear the plastics under rear seat and cutouts in seat to increase head clearance look like they had been lifted from "C".

Do they really move 12v under the hood, or it is in the same place like on "C" under right rear passenger seat?

 

And if under the hood, is it a traditional flooded battery? That could save a few bucks, loosen up the replacement choices as well.

 

Another lab test tells us the Prius G3 system output is 140.4ps (103kW).

Ken@Japan

 

Looks correct to me. In addition I would guess:

• ICE is attached to the right, upper side (we can see the damper disk)
• View is from top of vehicle
• Top of the image is front of vehicle, bottom is torwards cabin
• At the bottom of the image we can see the differential
• MG1 is now further away from the heat of the ICE, maybe better efficiency?

MG1 and MG2 are so close, I wonder if their magnetic fields overlap. OTOH magnetic fields lose their power quickly with distance.

 

Purely editorial, but I wish "ICE" would revert to "engine": the "heat of the ice"??

 

From my days doing support for circuit development, ICE is In Circuit Emulator. So I can't get used to using it this way either.

 

Does it have to do with a "Parallel Gear THS-III system" mentioned by Kaizendo?

The Temple of VTEC - Honda and Acura Enthusiasts Online Forums > Today's Reading Links > > Prius IV / THS III Transaxle to be Parallel Gear instead of Planetary Gear

 

That was wrong rumor regarding to the Power Split Device, the main planetary gear set.

Ken@Japan

 

both US and EU press releases specifically stated double-wishbone... since it is all new platform, it is not lifted of Auris, but new development.

 

Japanese nav is not the same as EU and US navs... in the EU, Prius will certainly have nav instructions on trip computer as well, since all of our recent Toyota's do.

 

Weight is +10kg on middle grade model.

We already know it will get 10% better mpg under EPA and 18% better under EU test.