The Electric Car
in [Design]
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From: James Arthur on 7 Aug 2007 15:35 On Aug 7, 12:11 pm, Jim Thompson <To-Email-Use-The-Envelope-I...(a)My- Web-Site.com> wrote: > On Tue, 07 Aug 2007 11:36:32 -0700, James Arthur > > <dagmargoodb...(a)yahoo.com> wrote: > >FWIW, I've always gotten about 20% better than EPA-rated fuel economy, > >by carefully optimizing my driving. > > >I had been driving 55 mph, then even 50 mph in an attempt to improve > >my Acura's mpg. Careful cross-country measurements show optimum fuel > >economy to be 41mpg, which applies from 85 down to 65 mph. Going > >slower reduces mpg. > > >A gearhead pal offered a decent explanation of how providing the > >engine with optimum load and RPM by going faster makes my particular > >engine more efficient, making up for the windage loss... up to a > >point, of course. > > > I'm getting 19MPG at 85MPH in my Q45 ;-) > > ...Jim Thompson I'm surprised your Q45 isn't a little better on the highway, truthfully. Not that 19mpg is particularly bad, all things considered, but I just got back from Alaska, where a pal and I got 19mpg in a Ford van (that was transport and lodging both). Of course that was @ 55mph. ICEs like constant torque. I save gas by accelerating slowly, coasting before braking, slowing up hills, and speeding up (or coasting to control speed) on the downside. Cheers, James Arthur
From: Jim Thompson on 7 Aug 2007 15:38 On Tue, 07 Aug 2007 12:35:19 -0700, James Arthur <dagmargoodboat(a)yahoo.com> wrote: >On Aug 7, 12:11 pm, Jim Thompson <To-Email-Use-The-Envelope-I...(a)My- >Web-Site.com> wrote: >> On Tue, 07 Aug 2007 11:36:32 -0700, James Arthur >> >> <dagmargoodb...(a)yahoo.com> wrote: > >> >FWIW, I've always gotten about 20% better than EPA-rated fuel economy, >> >by carefully optimizing my driving. >> >> >I had been driving 55 mph, then even 50 mph in an attempt to improve >> >my Acura's mpg. Careful cross-country measurements show optimum fuel >> >economy to be 41mpg, which applies from 85 down to 65 mph. Going >> >slower reduces mpg. >> >> >A gearhead pal offered a decent explanation of how providing the >> >engine with optimum load and RPM by going faster makes my particular >> >engine more efficient, making up for the windage loss... up to a >> >point, of course. >> >> >> I'm getting 19MPG at 85MPH in my Q45 ;-) >> >> ...Jim Thompson > >I'm surprised your Q45 isn't a little better on the highway, >truthfully. Not that 19mpg is particularly bad, all things >considered, but I just got back from Alaska, where a pal and I got >19mpg in a Ford van (that was transport and lodging both). Of course >that was @ 55mph. > >ICEs like constant torque. I save gas by accelerating slowly, >coasting before braking, slowing up hills, and speeding up (or >coasting to control speed) on the downside. > >Cheers, >James Arthur In case you couldn't draw the conclusion... I'm (surprise, surprise) an aggressive driver ;-) ...Jim Thompson -- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | | http://www.analog-innovations.com | 1962 | America: Land of the Free, Because of the Brave
From: Eeyore on 7 Aug 2007 16:07 Spehro Pefhany wrote: > Eeyore wrote: > >MooseFET wrote: > >> JosephKK wrote: > >> > Mark makol...(a)yahoo.com posted to sci.electronics.design: > >> > > >> > >> 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. > >> > > >> > Yes, and flywheels bring their own issues with changes yaw, pitch > >> > and roll. There will have to be space for the flywheel to spin not > >> > only during normal driving but the vehicle must not become a hazard > >> > if it rolls over in any direction or spins out. > >> > >> I think compressed air is a better way to go. > > > >Compressed air power storage is horribly lossy. > > Was that proposed compressed air car debunked? It looked pretty iffy > to me, though compressed air or a hydraulic accumulator might be fine > for a hybrid. The MDI air car ? It exists after a fashion but it's still not in production. I doubt it ever will be, it has no really useful range and doesn't go very fast. I assume you bring a paraffin heater with you to keep it warm in winter. Graham
From: Nobody on 7 Aug 2007 16:21 On Tue, 07 Aug 2007 18:20:01 +0000, Rich Grise wrote: >> Yes, and flywheels bring their own issues with changes yaw, pitch >> and roll. There will have to be space for the flywheel to spin not >> only during normal driving but the vehicle must not become a hazard >> if it rolls over in any direction or spins out. > > Well, that's simple - just put the flywheel's axis vertical. That doesn't allow for hills. OTOH, it might be a perfectly viable solution in the Netherlands.
From: Guy Macon on 7 Aug 2007 16:42
Don Lancaster wrote: > >Guy Macon wrote: >> >> Don Lancaster wrote: >> >>>The energy density of compressed air is ludicrously low. >>>Typically one sixth of lead acid or worse. 15 wh/l is hard to acheive. >>> >>>The efficiencies of most compressed air motors are much worse than an >>>ICE. Typically 29 percent or less. >>> >>>No means of efficiently compressing air is known. >>>Efficient compression requires isothermal operation, which can only be >>>approximated by elaborate and costly multi-staging. >>> >>>The fire service proved all this a century ago after throwing bunches of >>>engineering at the proglem. >>> >>>The ONLY thing compressed air has going for it is shop floor >>>convenience. Hydraulics immediately get substituted when serious tail >>>twisting or anything remotely approaching efficiency is needed. >> >> The ONLY thing? >> >> There are other advantages. With pneumatics the light-load >> cycle rate is higher, the piping for distribution doesn't >> need to have a return path, and in some clean-room applications >> the system can tolerate traces of ultrapure gas leaking into >> the working area, but not any sort of liquid. >> >> Hydraulics win for strength, efficiency, positional control, >> stiffness, and safety if a pipe or cylinder bursts. >> >> You will never see pneumatics in a bulldozer, and you will >> never see hydraulics in a machine that puts CDs into CD >> cases. Having worked as a design engineer for both Parker >> Hydraulics and SMC Pnuematics, I don't see either of them >> cutting into the other's business. > >And the number of pneumatic combined CD case stuffers and >automobiles currently on the road is....? Approximately the same number as cars on the road for whom "shop floor convenience" is an important consideration. Why do you ask? -- Guy Macon <http://www.guymacon.com/> |