Nobody understands the point of hybrid cars [video]
youtube.com44 points by CHB0403085482 2 days ago
44 points by CHB0403085482 2 days ago
So this is specifically about Toyota's hybrid engines (which is very different from e.g. Honda's engine, not to mention plug-in hybrids or "mild hybrids"). The explanation of the mechanics starts around the 36 minute mark.
I always found most explanations of Toyota's Power Split Device too abstract, until I found this page where you can play with the sliders to see how the power is actually split between the ICE and the MG1/MG2 electric generators: https://eahart.com/prius/psd/
I saw some parts of this video, so I'm not sure it was mentioned, but the key parameter that is optimized at all times in a hybrid is brake specific fuel consumption:
https://en.wikipedia.org/wiki/Brake-specific_fuel_consumptio...
This is possible (and done) in any automatic, but in hybrids it was taken to the extreme, with electric motors covering for situations when either the RPM or torque are not where desired.
In fact, my experience is that during highway driving it's actually slightly off the optimal point, charging the battery in the process. I speculate that it's so that the surplus power can be released immediately by just making the electric motor stop acting as a generator and go into, well, motor mode.
I recently bought a hybrid, and had been trying to wrap my brain around how it had an Atkinson engine in it. Was imagining a solenoid-driven crankshaft linkage or similar. Loved learning from this video that the secret is in valve timing and not fancy linkages.
But. The other points made felt muddled or even contradictory. I either didn't follow the TC guy's explanation closely enough, or the script could have used another pass.
Watching the graphs during the driving segment helped me more than his explanation, but maybe I'm visual about it? It's interesting to see when the battery is being used.
I've seen some modern hybrids just have a visualizer for this on the dash to encourage you to coast more and things, which seems about as helpful in understanding it too.
I'm assuming that right now all valves as computer controlled so why we cannot have best of both worlds? cannot we dynamically switch between Otto and Atkinson cycles by just changing valve profiles?
computer could use Otto cycle in case more power is needed in rare situations
> cannot we dynamically switch between Otto and Atkinson cycles by just changing valve profiles?
Toyota introduced this exact behaviour with their "Variable Valve Timing-intelligent Electric" (VVT-iE) system:
https://toyota-club.net/files/faq/16-01-01_faq_vvt_ie_eng.ht...
It uses an electric motor to control intake valve timing.
AFAIK all values are controlled by a camshaft. The computer doesn't get enough control. Solenoids seems like that are a possible replacement for CAMs, but they apparently have too many downsides.
I have a conventional (not plug-in) hybrid Toyota Corolla as otherwise I'd have to pay loads to drive it in the city.
It does get crazy mileage and drives well so I can't complain. They are more expensive than standard cars though and you can't leave it in neutral which is a problem in some car washes.
Before seeing the sibling comment here this is muddled or contradictory -- I'd shared the link on (having watched it in full) noting this may be the best explainer of this nature for its target persona that I've seen.
this was a great video