Another 2010 review

I was fascinated by the engineering, cut-away model:



We see what appears to be a two-stage, catalytic converter with the second O_{2} sensor. The next assembly, "Exhaust Heat Recirculation System" has two pipes, one colored pink and the other blue that goes to an over sized housing and some sort valve before the large resonator. The other ends of these two pipes goes:



The blue would be cool coolant and the pink the hot. We already know the Prius typically achieves catalytic converter operation within ~40-45 seconds. The heat from the converter feeds to the exhaust heat recovery unit and then feeds the engine block. What isn't clear is how the system handle the subsequent higher temperatures without stressing the coolant. Since the blue pipe appears to go into a cylinder with rod that may go to a valve, this may be how flow is handled.

CORRECTION: My thanks to David Beale who pointed this is the coolant heat exchanger that gathers heat from the exhaust. EGR remains an open question. I was able to confirm this by blowing up the original photos to read the labels.​

I've not really studied exhaust gas recirculation (EGR) other than Julian Edgar's article. EGR helps reduce the combustion temperature and NOx emissions, which in turn allows a leaner mixture. If you look closely at the exhaust manifold, you'll see four pipes that feed into a central pipe and then a short pipe, probably the exhaust tap, that feeds to the left.



This photo shows the coolant pipes from the exhaust heat recovery system connected to the engine block. This eliminates the need for a thermos bottle and rapidly warms the engine.

The following photo shows how the larger inverter electronics now extends into the space formerly occupied by the transaxle, which is much smaller.



You can see the input manifold is plastic, similar to the Camry. Also, there still is a huge throttle plate. It looks like the cooled, exhaust gas passes from a pipe located just to the left of the top of the inverter. We can't easily tell where this feeds into the intake manifold. But you can really see the reduction of the transaxle.



The traction battery still has 28 modules identical to the current ones. However the housing is smaller. On the far right is a separate control electronics box and then a squirrel cage fan. With the control electronics as what appears to be a separate housing, battery replacement will be much easier.

OPINION: HSD does not require a significant amount of of electrical energy to keep the engine systems running at peak efficiency. The energy recirculation dance between MG1 and MG2 do all of the 'heavy lifting.' As such, the higher energy density of the LiON is not really needed.

SPECULATION: Consider this, even with this marvelous traction battery, the vehicle _STILL_ uses an ordinary lead-acid, 12 VDC battery boat anchor. In a perfect world, the traction battery control electronics would provide the 12 VDC power and the lead-acid battery that would ordinarily be located about two feet behind the traction battery would disappear. This would save as much weight as a spare tire (or that space around my fat belly.)

Here you see where for the show the auxiliary battery has been disconnected and a power supply provides the 12 VDC needed for the vehicle electronics. It sits on the right hand side just under 2 ft. (1/2 meter?) behind the traction battery control electronics. The tire well is huge and deep. The cover has about a 3-4 inch, ~10 cm padding. It might be just the right size for a bunch more battery modules as well as the space above the tire well.



There appears to be a bit more space for long legged individuals. However, I think we can wait on the official vehicle cabin specifications. I understand they've added 5 cu. ft. more space.



Looking at the right rear:



The rear suspension uses a coil and shock absorber mounting. You can also see the muffler is well shielded by the rear axle and there is excellent heat shielding between it and the body. On the right appears to be a rear wheel 'mud flap' but in reality an aerodynamic shape to reduce drag (or trap winter snow and ice???)



The chief engineer, Akihiko Otsuka, who spent a long, long, day dealing with a lot of curious Prius fans who babbled at him in a foreign language, English. He was gracious, patient and totally overwhelmed by our insatiable curiosity.

Bob Wilson