O.T. electric cars - do they have gearboxes?

On 23/04/2017 08:13, harry wrote:

This turns out not to be the case.
You can, for example, use the warm exhaust to preheat the incoming air & fuel.
Andy
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On Sun, 23 Apr 2017 21:37:06 +0100, Vir Campestris wrote:

Mother nature has beaten us to this 'trick' as can be seen in the anatomy of penguins' feet where the veins and arteries in their legs run side by side so as to allow the veins to recover heat from the arteries before it gets lost by contact with the ice upon which they roost or walk. The feet themselves are little more than bones, ligaments and tendons acting as remote controlled low temperature tolerant appendages.
In the case of the flash boiler, the hot combustion products are routed in a contra-flow to the direction of the feed water flow from the condenser and the boiler unit itself is extremely well insulated to minimise unproductive heat loss through the casing.
Getting back to the original question, most electric vehicle designs eliminate the mechanical variable ratio gearbox, electing instead to use high power handling switching converters to control the motor speed instead. Even when a design uses a fixed gear ratio box to better match the loading on the drive motor, electronic drive voltage control is still the method by which modern electric road vehicles are speed regulated.
In an ideal setup, you would have hub motors in each wheel which could be arranged as a series wired pair on each axle to provide a built in differential and halving of the current required to drive each axle's worth of hub motors.
However, in order to maximise efficiency and power to weight performance of electric traction motors, you get the best performance using a high rpm motor[1] which basically precludes direct drive hub motor designs unless you're prepared to sacrifice top end performance for improved battery economy at more modest urban traffic speeds (you replace mechanical transmission losses with much lower electric cabling losses).
[1] High rpm on account it uses less turns of heavier gauge copper in its windings, meaning reduced I squared R losses.
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On 24/04/17 03:31, Johnny B Good wrote:

But needs more current to achieve the same magnetic moment.
No, what counts is magnetic reversals per second, times the iron mass.
You can achieve that with a lot of poles, or a lot of RPM.
Copper losses turn out to be pretty much independent of the configuration, and are a more a function of as you say RPM BUT its not 'RPM' that matters, its 'poles per second'.
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On Sunday, 23 April 2017 21:37:09 UTC+1, Vir Campestris wrote:

The effect is negligible and leads ot all sorts of control problems. The specific heat of air is low.
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On 24/04/2017 07:43, harry wrote:

Well, I suggest you go and look at your nearest power station.
There's a nice model of one in the Science Museum.
Andy
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On 24/04/2017 07:43, harry wrote:

What? Are you really trying to suggest the temperature of combustion is independent of incoming air temperature?
There are even recuperative furnaces for smelting. I suggest you look up 'recovery boiler design' before showing any more ignorance.
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On 20/04/2017 19:24, Nightjar wrote:

Ta. And a video of it

https://www.youtube.com/watch?v=rUg_ukBwsyo

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On Thursday, 20 April 2017 17:41:08 UTC+1, Nightjar wrote:

A steam engine is not an ICE.

Few ICE cars can do this.
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On 21-Apr-17 8:41 AM, harry wrote:

My point was that electric cars are not unique in that respect.

Mine can, which is why I chose it rather than something else, although I did have to specify the extended fuel tank to get the range. No existing electric cars could even get close.
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On Thu, 20 Apr 2017 00:18:50 -0700 (PDT), harry
Hmm, I've owned an electric car for over 30 years and I'd say that whilst it has it's merits, it still has too many limitations to be the primary vehicle for many (even excluding the annual holiday etc).
One of it's merits is it's simplicity (not sure it would be the case these days?). When I first got it home (on a trailer behind my IC car) I thought I'd give it a good check over. I checked the brakes, the lights and the battery electrolyte levels ... and that was about it.
Ok, I know most production PEV's can go faster than 30 mph and a range greater than 20 miles but the concept / limitations are still similar.
Now, as it happened I worked only 1/4 mile from the house so one (20p) charge would get me to work and back (and at lunchtime) for a couple of weeks at least (assuming I didn't go anywhere else).
It was also exempt the MOT (at the time) and carried Zero Road Tax (but you still had to have a Tax disk <g>), was insured at about the same cost as the original BL Mini and obviously ignoring the initial cost / deterioration of the batteries, had hardly any other running costs.
Not sure how many PEVs can tow a trailer or take roof bars?
Cheers, T i m
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It depends. Many do not have them and use motors driven a bit like those in CD players with constant torque no matter ewhat speed, while others use gear trains but motors running quite fast. Of course hybrids are far more complicated.
The problem with quiet cars though is that crossing the road in poor visibilityccan be very dangerous. Brian
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On Thursday, 20 April 2017 08:48:46 UTC+1, Brian Gaff wrote:

Drivel.
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On 19/04/2017 19:47, Murmansk wrote:

We looked at the Tesla and were told it didn't have a gear box.
We decided against all electric, we don't like the idea of being stuck with a 'flat' battery on a journey. The idea of stopping for 'top ups' on a long journey is fine until you consider the practical aspects.
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As a matter of interest, is anyone looking (as in considering making) a hybrid electric? As in, rather than having a powerful petrol engine, a less powerful electric motor, a normal size fuel tank and a smaller battery (like my Toyota Auris), instead have a full-size electric motor, larger battery, but with a small petrol engine and small fuel tank?
That way one could stop anywhere to recharge or even do it on the go.
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On 4/20/2017 5:23 PM, Tim Streater wrote:

You mean like a Prius?
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Which one. The Prius hybrid is just the same as my Auris hybrid.
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On 4/20/2017 6:19 PM, Tim Streater wrote:

Ah. Do you mean a Prius with a charging socket? I am almost sure I have heard of a rechargeable electric with a small IC engine for optional charging (but not a Prius). Maybe it was a prototype.
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On Thursday, 20 April 2017 20:09:44 UTC+1, newshound wrote:

It's called a "Plug In Hybrid" They are common Eg Mitsubishi make one called PHEV.
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On 4/20/2017 8:17 PM, Theo wrote:

Oh good, I didn't imagine it!
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