Post #420,892
10/18/17 2:58:02 PM
10/18/17 2:58:02 PM
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Gas/electric hybrid question
Today's gas/electric hybrid vehicles graft a battery and electric motor onto an existing drivetrain. When the battery goes dead the ICE takes over. Is anyone working on something along the locomotive model where the ICE is strictly a generator?
With the generator model you can eliminate the entire drivetrain and transmission and go with electric motors per-wheel. The generator can be far more efficient as it only needs to run at a single highly-optimized speed. You can program it for max-battery use for daily commuting when you expect to go less than the max range before plugging in; or long-haul mode where it kicks in at say 50% and runs until you're back up to 75%.
How much smaller an ICE could you get away with doing this model? What would happen on extreme long-haul days where you conceivably run out the battery?
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Post #420,893
10/18/17 3:09:16 PM
10/18/17 3:09:16 PM
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The Chevy Volt was originally kinda-sorta along the lines of what you proposed.
E.g. http://www.plugincars.com/exclusive-video-want-know-exactly-how-chevy-volt-powertrain-works-95344.html (with videos). There are lots and lots of compromises in making an electric car. I wouldn't be surprised if packaging was one of the reasons why they don't put a motor near each wheel. Reliability and maintenance might be better/easier with a single motor and drive shafts, etc., to the relevant pair(s) of wheels, also too. Crash test results might be a constraint, too (having lots of mass near the center of the car, rather than at each wheel). Just a guess. HTH a little. Cheers, Scott.
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Post #420,894
10/18/17 3:49:03 PM
10/18/17 3:49:03 PM
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I believe BMW's i3 REX is like that.
The base model i3 is pure electric. The REX option literally means "Range Extender".
Wade.
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Post #420,895
10/18/17 4:03:04 PM
10/18/17 4:03:04 PM
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Interesting
The 2.4 gallon tank gives an extra 66 miles of range, so 27.5 mpg. That doesn't sound so great.
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Post #420,896
10/18/17 4:41:38 PM
10/18/17 4:41:38 PM
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My 20 year old accord gets better mileage than that
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Post #420,902
10/18/17 7:27:52 PM
10/18/17 7:27:52 PM
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Number salad
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Post #420,904
10/18/17 8:20:25 PM
10/18/17 8:20:25 PM
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That must be the thing I see on the freeway now and then . . .
. . that looks just like a miniature Pontiac Aztek. When I see one I think, "What were they thinking?".
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Post #420,914
10/19/17 1:31:42 AM
10/19/17 1:31:42 AM
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That sounds about right.
The i3 is a modern "city car", which means short and round and tall but probably very manoeuvrable.
BMW have been trying to drum up support here in Oz as it's the same price the Tesla Model 3 is expected to be. However it has the half the range and two thirds the size.
Wade.
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Post #420,901
10/18/17 7:15:13 PM
10/18/17 7:15:13 PM
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was working on something similar back in the 1990's with a friend genuis of mine
he got the mechanics and drawings figured out but the difference he had was the ICE drove a generator which pushed a hydrolic motor (picture tiny helocopter rotors driving each wheel) "Science is the belief in the ignorance of the experts" – Richard Feynman
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Post #420,921
10/19/17 8:14:47 AM
10/19/17 8:14:47 AM
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For the long haul, constant speed is pretty frugal, so shouldn't make you need too big an engine.
Especially if you can be satisfied with some sensible speed; at cruising speeds aerodynamic resistance becomes the main drag (heh.) on fuel consumption, and that rises with the square (or cube?) of the rise in speed. But staying under, say ninety MPH and with at least a reasonably aerodynamic body (as modern low-fuel and hybrid cars tend to have), I'd guess something like a 1.2 - 1.5 l three- or four-cylinder petrol producing 100-130 HP would be more than enough to both propel you down the freeway and re-charge the battery at the same time. Perhaps even overkill; might be you could get away with little more than half that. The BMW i8 has a 1.5-l I3 turbo with a comparatively humongous 230 HP, but then that's a sleek mid-engined supercar wannabe thingy. --
Christian R. Conrad
Same old username (as above), but now on iki.fi(Yeah, yeah, it redirects to the same old GMail... But just in case I ever want to change.)
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Post #420,928
10/19/17 8:32:51 AM
10/19/17 8:32:51 AM
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Yup. My Jetta only needs ~ 20 HP to cruise at 55 MPH.
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Post #420,940
10/19/17 5:18:12 PM
10/19/17 5:18:12 PM
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No, no, no!
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