Quote:
Originally Posted by dcb
Im with you 100% on the get rid of the throttle/pumping losses, but I have yet to see anything that approaches 98% efficiency in terms of cvt or "electric transmission" under a wide range of vehicle speeds.
Not to totally hijack here, just wondering if there is a source (link) that someone has actually solved the myriad number of issues with %98 efficient transformation/storage of power to keep the engine happy under a wide range of vehicle speeds and loads.
My beef is that the engine being at/near happy bsfc in this scenario seems to require a vaporware transmission and storage scheme (vs an honest to goodness real driver).
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I don't have,nor have I ever seen a mechanical powertrain efficiency rating above 95%,so I've just kinda stored that value away in the back of my mind as the 'best-case.'
For the modern hybrids,I think the notion of getting the engine into,and keeping it at the 'sweet-spot' is driving the interest in the CVT and serial -hybrid.
Honda's 1st-gen Insight had a 5-speed manual,geared for good BSFC if you 'kept yer foot out of it.'
The new Insight,with CVT will allow velocity to drift around a bit while maintaining a good BSFC.
Same for the VOLT.After 40-miles,when the batteries peter out,the constant-speed engine will fire up like a stationary generator providing enough juice for the elec traction motor and re-charging.It should be very efficient,but even,say at 40% at the engine,there'll be a couple % loss at the generator,and again at the motor.If the Volt has a planetary gearbox like EV1/2,then there should be another 5% loss before the power makes it to the wheels.
If VOLT has the Ultralite tires,that will be good for 2.6 mpg.That will help some.
Volt isn't as low-drag as EV1 so she'll lose back some efficiency there.Too Bad.But it looks like a Cadillac CTS so it shouldn't scare potential buyers away on account of 'styling.'
In 1992,there was a Infinitely Variable Transmission ( IVT ) under development with Epilogics Inc.,Los Gatos,California, invented by Paul Pires.
Epilogics was 'looking' for a 30 % fuel economy improvement with it.GM/Mercedes-Benz/Roger Penske's Detroit Diesel Corp. was looking at it.They would have been subtracting out their efficiency losses before arriving at the 30% mpg improvement.Pretty tasty!