10 ms·

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

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.

Szpadel 4mo ago
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
- bluGill 4mo ago
  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.
  - vel0city 4mo ago
    Koenigsegg has an engine design that has a camless valve system based on their "Freevalve" technology. Its pretty cool. https://en.wikipedia.org/wiki/Koenigsegg_TFG https://en.wikipedia.org/wiki/Koenigsegg_TFG
- Tade0 4mo ago
  > 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.htm https://toyota-club.net/files/faq/16-01-01_faq_vvt_ie_eng.ht... It uses an electric motor to control intake valve timing.
nemomarx 4mo ago
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.

Szpadel 4mo ago

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

bluGill 4mo ago
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.
- vel0city 4mo ago
  Koenigsegg has an engine design that has a camless valve system based on their "Freevalve" technology. Its pretty cool. https://en.wikipedia.org/wiki/Koenigsegg_TFG https://en.wikipedia.org/wiki/Koenigsegg_TFG
Tade0 4mo ago
> 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.htm https://toyota-club.net/files/faq/16-01-01_faq_vvt_ie_eng.ht... It uses an electric motor to control intake valve timing.

nemomarx 4mo ago

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.