The Electric Car
in [Design]
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From: JosephKK on 2 Aug 2007 20:47 Eeyore rabbitsfriendsandrelations(a)hotmail.com posted to sci.electronics.design: > > > MooseFET wrote: > >> Eeyore wrote: >> >> > The current hybrids also use skinny tyres to reduce rolling >> > resistance. I hate to think of the adverse effect on road >> > holding. >> >> There is basically no difference in the traction. Wide tires >> look cool but below a certain amount of force per unit area of >> rubber give >> no traction advantage. The traction loss in thing tires is >> because the force on the surface is high enough to rip bits of >> the rubber or >> the road loose. They modern materials in the tires are less >> subject >> to this problem. The cars we are talking about are quite light >> too. > > I'm not talking about traction, I'm talking about road holding / > handling. And just how, exactly, do you separate the two (dealing with tires only)? Both are ultimately limited by friction limits. > I know American roads don't have corners (or at least > from the way US cars drive you'd think that was the case) but we > do here. We have them on residential streets. ;^) > > Which reminds me... why do Americans seem to want such big engined > over-powered cars when most of them fall off the road so easily if > you use it ? Is it just a macho thing ? > > > Graham
From: Eeyore on 2 Aug 2007 21:57 Mark wrote: > > > > It seems to just argued against using any electric motors at all. > > > > Yep, I think the small batteries and electric motor in the Prius are > there for only 2 reasons.. > > 1) efficency gained by regenerative braking > 2) improve the acceleration so the ICE can be smaller also improving > the efficency. > > If you had the small ICE without the acceleration boost provided by > the electrics, the acceleration would be poor and people would not > like the "drivablility". > > Intersting to note that a flywheel could provide the same advantage. > > In fact I tend to think of the battery and electric motor in the Prius > is just an electric implementation of a flywheel. A flywheel would be so heavy as to make the car undriveable too. Not to mention the gyroscopic action ! Graham
From: MooseFET on 2 Aug 2007 22:22 On Aug 2, 6:41 am, Eeyore <rabbitsfriendsandrelati...(a)hotmail.com> wrote: > MooseFET wrote: > > On the highway, the engine gets connected directly to the wheels. > > This takes the sosses of the electric machines out of the picture. > > What losses ? Electric motors are highly efficient. Yes exactly. The losses in the electric motors. > > > It also allows the engine and both motors to be used for passing power. > > At the cost and complexity of requiring a transmission. I just don't see any sense in it. It gives about 15% better fuel economy on the highway and about double the merging power. I say Toyota did the right thing. > > Graham
From: Eeyore on 2 Aug 2007 22:32 Nobody wrote: > Mark wrote: > > > Intersting to note that a flywheel could provide the same advantage. > > > > In fact I tend to think of the battery and electric motor in the Prius > > is just an electric implementation of a flywheel. > > There has been research on using flywheels, primarily for buses. The > problem is that you need a (relatively high-torque) variomatic > transmission to avoid shearing the gears and/or incinerating the clutch. Flywheels are very impractical energy stores. The gyroscopic forces don't exactly help in vehicle use either. Graham
From: Eeyore on 2 Aug 2007 22:40
Glenn Gundlach wrote: > Interesting here > > http://www.cleangreencar.co.nz/page/prius-petrol-engine Good article. I've rarely seem so many of those issues discussed together and seen them so well explained. Graham |