2012 Toyota Camry Hybrid XLE: Technology In A Mid-Size Sedan

[tuanies]

From article;
"Although the Atkinson cycle yields greater efficiency, it sacrifices peak power in the process. The result is a drop from 178 hp and 170 ft-lbs of torque to 156 hp and 156 ft-lbs of torque. This is where the electric motors step in."

Actually, Atkinson cycle has worse low-end power. So, the electric motors really help then to provide power when the engine is turning quickly.
You could say that it turns the drivetrain into the equivalent of a Miller cycle 'engine'. Really a Miller cycle engine is an Atkinson cycle engine with a supercharger installed to boost low-end power. But, in this case it's electric motors doing it.

Atkinson is nice but HCCI is what the next step is. Where a gas engine can function as a diesel on demand, no spark plugs used during certain conditions. Compression ratios are modified via valve behavior, pressures measured in each cylinder. It's pretty tricky to get gasoline to ignite when you want it to, and I guess diesel too.

Diesel does it by squirting in the fuel right when it's time to ignite. Gas engines squirt beforehand.

Updated. Thanks. The Miller Cycle is really cool, but seems overly complicated. I still love the Mazda Millennia though.

HCCI - wouldn't that be kind of like direct combustion then?

 

[danwat1234]

@Tuanies,
I don't know that much about HCCI. But I do know a bit about it.
Somehow efficiency is increased. The compression ratio hast to be around 14:1 or so in order to burn gas without a spark, I think. The engine would operate part time as an HCCI engine, like when engine load is low. At certain RPMs and engine loads it'll switch back to regular OTTO or Atkinson cycle. I've heard on the Internet that maybe an improvement of 15% in efficiency might be possible. It's clear to me that the piston engine is getting to be about as good as it's going to get.

Also I think all HCCI engines will control the amount of air that gets into the cylinders by continuously variable valve lift, rather than using a butterfly valve (throttle plate) to control the amount of air getting into the intake manifold. This is needed (I think) so that each individual cylinder can get a different amount of air via independant valve lift so the gas will ignite at the right time. This should also aid in efficiency a bit as the throttle plate won't be creating pumping losses. I think regular gas cars will get this valve lift technology soon too for a bit more MPG.


You wrote the article? I think you might have made a typo in the regenerative braking section of the hybrid synergy drive page when you mentioned heat from the brakes being used to charge the battery. The heat from physical braking isn't captured.

 

[Guest]

Just cheap Japanese cars. Get a proper well-engineered German car, not these car-wannabes.