Toyota Unveils Advanced Prius Tech

All of this is bathed in transaxle fluid? I thought I read that in other posts about the transaxle. The electric motors are not dry?

 

Active could likely be to distinguished it from traditional brake boosters. In them, the boost for the power brakes is powered by the vacuum produced in the air manifold of a spark engine. This vacuum also produced inefficiencies to engine operation known as 'pumping loses'. The vacuum is an area of low pressure made behind a partially opened throttle plate. While engineers have tapped this vacuum for boosting brakes and operating other accessories, it sucks back on the descending cylinders while the injection valves are open. It's like breathing through a stuffy nose.

Reducing pumping losses will increase the overall fuel efficiency of the engine, but you can end up without enough vacuum to boost the hydraulic brakes. Diesels, which have no throttle plate, thus no vacuum, simply use a vacuum pump, which then can power all the other vacuum powered subsystems developed for gasoline cars, like the EGR. Whether because the engine isn't always running to make vacuum(hybrid), or it simply doesn't produce enough vacuum pressure(tiny, turbochared ICE), a hydraulic pump like Bob describes is used to boost the brakes.

These are commonly called accumulators, because they store(accumulate) hydraulic pressure built up from a smaller pump. I guess a larger pump could replace the entire system, but it is less efficient and/or costs more, and the accumulator can provide brake boost for some brake applications in the event that the pump fails.

This on a larger scale is how hydraulic hybrids capture brake energy.

The limits on regen brake capture is on the electrical side of the driven train. In regards to hybrids, it is mostly limited by battery size and chemistry. Pumping energy into the pack produces heat because of the cells internal resistance, and too much will damage it.

 

improve brake feel and control while reducing noise reduction, the all-new Prius utilizes a newly-developed active hydraulic booster for its regenerative brakes.

Thank you for the explanation. I figured that the Prius didn't have the kind of brake booster that I have been used to, but I thought it was because the ice isn't on all the time. It interesting to think about "pumping losses" and their effect on efficiency.

The more one learns about its engineering, the more exciting this car becomes.

 

Well, it is because the engine isn't running all the time. But I also know my Sonic with the 1.4L turbo has some type of active booster. Like electric steering, we'll start seeing active brake boosters, and other once hybrid only tech, on more cars as more efficiency is squeezed out of the ICE.

 

At the local EV club the other day, we had an extensive discussion about tweaks Nissan did to Leaf over the years. The 2015 drives much better & further than the 2012, despite being the same generation. Engineers were allowed to release an array of updates along the way.

It's quite realistic for us to see a collection of performance improvements with the next Prius PHV. Toyota never stopped research & development, despite what the naysayers spin.

Too bad so many people get hung up on maximum ratings. As a result, they totally overlook actual utilization. Put simplistically, what is the point of a 60kW rated electric-motor when you only have a battery-pack delivering 38kW of electricity? Making the two better match is an optimization easily not recognized. Yet, things like that are what contribute to overall improvement.

We already know the engine has been improved, delivering a 9% gain in the winter. That's a big deal. Some will complain anyway, focusing on the fact that the engine still runs at times... even though the resulting efficiency is noticeably better. It's a well thought out, versatile design. Both the regular model and plug-in will benefit.

We have many things to look forward to.

 

BIGGER, more powerful, 0-60 etc. are so 20th century...

 

Installing electric motors rated higher than needed contributes to the reliability of the Prius. If a less powerful motor was constantly being pushed to its maximum output the failure rate would be much higher.

Look at boat and small aircraft engines. They are constantly used near maximum power, and they require rebuilding after 1000 - 2000 hours of use. That same boat engine used in a car will have a much easier and longer life. Jet aircraft will many times have high output engines that are derated. Some of these engines will last 12,000 hours and more.

I'm not disagreeing with your post, just adding reasons why Toyota uses high output motors.

 

I doubt it, Maybe in very rare and extreme circumstances, 53 kW is a lot and you have an engine.
I think HGS meant continuously used.

 

Yes, when you need all system power..I think HGS meant continuous use.
For me: I have never floored the pedal.

 

Off the technical subject:
I've been looking at the head and tail lights of other 2015 Toyota vehicles, as well as the competition. While I really do not care for the head and tail lights on the new Prius, I can see that is one area to personalize the design. So many cars today have the same profile. If you were to remove the badges from many vehicles, it would be difficult for the casual observed to tell them apart. Head and tail lights are one area where they can "make a statement" that differs from others.

I consider Toyota's design different; distinctive but not necessarily youthful and or sporty.

 

It's all about right sizing. Interestingly, the hybrid Camry's MG2 is rated at 105 kW. That's not far from Volt's two-motor config rated at 111 kW.

 

When climbing the Eisenhower tunnel approach, I'll floor the pedal continuously for about 7 minutes. Vail pass is longer.

 

II am thinking the "rumored" reduced max power of 122hp might be due to them changing the way the combined output on paper? Since battery output (nimh) did not change at all, there should be no less battery output either. In current documents on G4, they ofter specify stronger acceleration but they dont specifically say it is faster. There is a diagram there that shows faster acceleration of G4 vs G3 as well.

 

thats what i meant as well... altough other manufacturers also simply add max battery output to max engine output.