Re: Reducing weight



Do you honestly believe that the only factors that can possibly affect the speed of an electric motor is load and voltage?
You poor, uninformed person!
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Thund3rstruck_N0i wrote:

no , run an ac motor and an scr , simple , sensor varies current and voltage as required , although a belt is much simpler and I expect a lot cheaper.

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atec77 spilled my beer when they jumped on the table and proclaimed in

But you still can run into the electric motor stalling.
NOI
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On Sat, 14 Feb 2004 11:31:52 -0500, Thund3rstruck_N0i

Davies Craig make one in a kit!
Oz1...of the 3 twins.
I welcome you to crackerbox palace,We've been expecting you.
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Marvin spilled my beer when they jumped on the table and proclaimed in

That was off the top of my head, but hey, if you want to discuss it, then start listing them.
NOI
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[followups set]

The voltage isn't lowered. The motor is driven by pulse width modulation (PWM) which means that the full voltage is available for a fraction of the time. The modulation frequency is typically in the 10's of kilohertz.

What are you doing here then? :-)
It doesn't have to be a _computer_. And it certainly wouldn't be Windows anyway.
--
/"\ Bernd Felsche - Innovative Reckoning, Perth, Western Australia
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Bernd Felsche spilled my beer when they jumped on the table and proclaimed
First off, thanks for the thoughtful reply.

Good idea. Unfortunately, I have been out of the Electronics field too long to have thought of that. :)

Not all cars have computers. :) Seriously, that was a tongue-in-cheek comment poking fun at my present career.

True. For instance a lot of cars today don't have to be reprogrammed everyday...
NOI
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Like NOI says. Instead of calling us uninformed, why not use the knowledge in you head and give us some reasons. I see that someone brought up pulse control of the motor. That is a fine idea, but it sounds rather expensive and how do the electronics in such a unit fare with changing ambient conditions? What else can you bring to the table?
...Ron -- 68' RS Camaro 88' Formula Bird
http://www.frontiernet.net/~rscamero
Some are wise and some are otherwise
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On or about Sat, 14 Feb 2004 11:31:52 -0500, Thund3rstruck_N0i
written:

Excuse me but isn't it called a thermostat? I seem to recall that most cars have had those for a few years now? The thermostat closes blocking the flow when the temperature goes down (the only reason you need to restrict flow) and opens when the temperature gets hot.
There is no need to maintain a constant load on the motor. The only potential problem is windage in the pump causing the water to boil if all flow is stopped but that isn't a problem because, if you recall, we have a thermostat near the pump outlet that allows flow when the water gets warm.
If you insist on controlling the motor then you use discharge pressure. Maintain a constant pressure at the pump outlet by decreasing voltage. If the motor starts to stall the pressure falls and the voltage goes back up. Same thing happens if the thermostat opens and the flow increases.
Now if you want a real problem, that electric motor is rather large and draws a hefty current. Where is that coming from? Now you need a BIG alternator. With a BIG belt or, better yet, gear drive. Because of losses converting mechanical motion to electricity and electricity back to mechanical motion, the electric pump is going to take more power from the engine than the simple mechanical pumps we have now. Now you need an automatic full throttle cut out just like we already have on the A/C compressors. But do you just cut off the pump risking overheating or do you cut off the alternator risking loss of all electrical power when the battery can't handle the load?
P.S. As an engineer I've seen more nonsense in this thread than most. Weight reduction can make a significant improvement in acceleration or it may never be noticed. The improvement is in direct proportion to the percentage of weight change. I have a 36HP motorcycle that weights 350 pounds with me aboard. It's FAST!!! Much faster than my Corvette. Put a 100 pound passenger on the back and it seems like it has trouble outrunning a Geo. But add 100 pounds to a Hummer and you would never notice.
A lot of people will waste good money on the latest "electro-magnetic vortex storm" gizmo that promises to add "up to 10hp" when they could get a guaranteed 10hp equivalent by a simple weight reduction that would also yield better handling. 10Hp in a 400Hp machine is the same as a 2.5% change in weight. You do the math. By the way, a gallon of gas weighs about 8 pounds.
Dale 85 Silver
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