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Why are all the new FE vehicles automatic??? :(

Hi ThirstyI4:

___Because we don’t live in Europe and American’s cannot drive sticks :rolleyes: That is for the main stream stuff … Wrt Toyota/Lexus’ HSD and Ford’s eCVT, the power split device has to be an automatic as the pack, (2) MGSet’s and ICE have to work together for the proper output. HCH-II? Because Honda wanted it that way incorrectly thinking it offers superior FE in more driving scenarios :(

___Good Luck

___Wayne

Part of the problem is that fuel efficient technology is slowly redefining drivetrain control as we know it. Taking Hybrid Synergy Drive as an example, it does things with the engine that improve efficiency long before you even involve the battery. Since spark ignition internal combustion engines (SI-ICEs) use a throttle plate, they suffer badly at low load. Plenty of energy is wasted when trying to draw intake air through the tiny opening that results when that butterfly is closed. Toyota's solution: keep the throttle open to 80% when the engine is in use. So right now you're probably asking, "OK, if the throttle is always wide open then what does the gas pedal do to control acceleration?" Answer: it tells the transmission to how fast to let the engine to operate, which is what really varies the power output. The position of your foot determines the gear ratio.

So there you have it. Foot-operated manual transmissions. :)

Part of the problem is that fuel efficient technology is slowly redefining drivetrain control as we know it. Taking Hybrid Synergy Drive as an example, it does things with the engine that improve efficiency long before you even involve the battery. Since spark ignition internal combustion engines (SI-ICEs) use a throttle plate, they suffer badly at low load. Plenty of energy is wasted when trying to draw intake air through the tiny opening that results when that butterfly is closed. Toyota's solution: keep the throttle open to 80% when the engine is in use. So right now you're probably asking, "OK, if the throttle is always wide open then what does the gas pedal do to control acceleration?" Answer: it tells the transmission to how fast to let the engine to operate, which is what really varies the power output. The position of your foot determines the gear ratio.

So there you have it. Foot-operated manual transmissions. :)


Does that really make sense? If the pedal didn't control throttle opening at all, then the only way to control power output (and thus fuel use) at every power stroke would be to change the air/fuel ratio, which would impact efficiency and emissions and could cause detonation. This is roughly how diesels work, but they are compression ignition so the situation is somewhat different.

Rather, my understanding is that the pedal does control throttle position. But, since the engine runs on the Atkinson cycle (the wikipedia article on that topic is pretty good, IIRC), the throttle is allowed to stay further open than it would on a more conventional engine, because part of the intake charge will be ejected from the combustion chamber before the spark. Thus you get more throttle opening and less pumping loss for a given volume of air/fuel to be burned. The 8th gen Civic's engine (non-hybrid at least) works similarly when the iVTEC system is in economy mode.

Clearly the accelerator pedal position impacts the drivetrain's choice of power distribution (and thus gear ratio to the engine) but I don't believe that's the means by which power is controlled.

EDIT: Please though, somebody correct me if I'm wrong.