Toyota Unveils Fuel-saving Technologies for New Prius

I can relate to that. In particular going around a low speed, counterclockwise 180 deg off-ramp. It's two way, and it's a real challenge, judging lane position, oncoming traffic, etcetera: where you're heading is right in the middle of that column.

 

Could well be and easy to achieve by changing the 'gear ratio' of the planetary set.

 

I am looking forward to counting the gear teeth in a high resolution photo. If the 28% counter torque is something smaller, more mechanical path and less electrical path.

Bob Wilson

 

As per the specs given, Gen 4 has weaker/less powerful Motors compared to Gen 3. There is no ambiguity there. But will those be weakest link? We do not know at this time.

But as I explained above(my guess anyways), new setup may not need as much conversion from ICE -Generator- Motor as ICE has better torque spread across the RPM range and can transfer power via new mechanical transmission to wheels better. Now, motors are not doing as much work as before, but potentially can take advantage of more power from battery adding additional torque.

 

Yes. Turning left at a busy intersection at night in the rain is challenging. I have to lean to the right and forward so I can see and not hit a center island curb or sign post.

The Gen 3 "A" pillar does have a considerable blind spot.

 

I know the gen 4 MG2 is 53 kW. Does anyone know what the gen 4 MG1 is rated at?

 

The new intake porting allows it to 'breath' better and accept a larger charge. I was wondering when folks would pickup on that.

There is another chart showing the relative rpm range of the current engine and next engine and the bragging rights about how they tweaked the operating line. No, the true operating line is not shown but two of the charts give a clue about how they did it.

Bob Wilson

 

Check Shunsuke Fushiki's presentation pages:

• 28 - shows the reduced ICE rpm, which means a larger fuel-air charge. Also, a little longer delay in New Prius engine start.
• 30 - shows the vehicle acceleration and those 'dotted-lines' look a lot like the engine power output at a fixed rpm but variable torque load.

I think the charts discussing the improved intake valving were part of a presentation on the 1.0 L engine. But they are using the same words including 'straighten intake manifold.'

Bob Wilson

 

I have added two values for y axis (vehicle speed).

EDIT See post #101 with correct numbers: 70 and 110 and the source for these.

 

Important point made in this graph is, ICE shutdown relative to Vehicle speed and acceleration. If you see the graph, the moment vehicle starts decelerating (even slow deceleration), engine is shutdown in Gen 4 Prius, where as in Gen 3, ICE rpm is lowered(may be idle RPM). Shutdown of ICE is occurring even at 72MPH in the Gen 4, where as on Gen 3, ICE is shutdown completely only when vehicle speed 45MPH or less(assuming km/h give are correct value on the above graph).

One thing that is not very clear here in Gen 3 is when engine shown as running at low RPM during the deceleration above 45MPH, is this DFCO mode or not?(I am guessing it is DFCO, ScanGauge would tell).

Gen 4 shows the Engine is not running at all during the deceleration. Does it mean that, is it completely disengaged from transmission? or its RPM is brought down to zero my managing the transmission ratios and motor speeds?

Irrespective of mechanism how ICE RPM is brought down to zero, Gen 4 has potential for easier and longer coasting distances(Hypermilers rejoice) because there are no ICE pumping losses anymore. Even in DFCO mode in Gen 3 ICE has considerable pumping losses via what we call engine braking. That is not there in Gen 4. Thought of adding another point here, this also means, more energy recovery from deceleration even without braking.

Of Course other observation already mentioned is, lower engine RPM relative to Vehicle speed which is a results of early peak torque in the RPM range. Frictional losses are proportional to Engine RPM and pumping losses proportional to Square root of engine RPM. So here more gain by reducing the pumping losses because engine is mostly operating at lower RPM.

All in all, I think Gen 4 will have better highway mileage in real world because of this and better Cd.

 

What is this term?

Bob Wilson

 

I added the rpm scale, because we know when old engine must run in deceleration it runs arround 1,000 rpm

96559_96554_Lower_Engine_Speed by GasperG posted Nov 3, 2015 at 8:41 AM

I think the graph is a little exchagerated to prove a point, but it's obvious that new engine will use more torque and have lover rpm under acceleration. Current engine uses only around 90-110 Nm under medium acceleration it looks like new engine will be run at 120-140 Nm very early in the rpm range. This will lower engine speed for the same acceleariton by 500 to 900 rpm.

To put it simple, it will have more grunt

 

That is true, but even Gen3 could be driven at higher torque, but it was not. It would be possible to run Gen3 engine at 120 Nm @2,000 rpm, but it was not because apparently that was not the sweet spot efficiency or maybe because of HSD restrictions/efficiency


If transition from 2nd gen to 3rd gen was -300 rpm, then transition from 3rd gen to 4th gen will be at least -600 rpm at same load.