DC Fuel Pump Controller

[iolair]

A hypothectical DC fuel pump is rated at 12volts/12amps and of sufficient power to maintain 39psi fuel rail pressure? The same pump is also safe to operate at 18volts.

With some kind of a controller (PWM?), could the pump then be run at 18volts/8amps and and still have enough power to maintain 39psi?

I'm not sure what kind of a trade off there is in rpm/torque with the two different configurations.

If it is possible, what are the advantages/disadvantages of the 18/8 config as opposed to the 12/12 config, if not, never mind!

....and yes of course, I don't know squat about electrical/electronic stuff!

Thanks/sorry!

John

 

[LionelHutz]

You are talking about a DC motor. As you apply more voltage it will try to speed up and pump more fuel which means doing more work and drawing more current.

You can not control the current without changing the voltage.

The voltage up = current down only applies to AC motors and it only applies over a small voltage change. In these motors the speed is fixed by the frequency so they are constant speed motors which means if they are driving a constant load they will be constant power. In AC, power is proportional to volts x amps - volts increasing means amps decreasing.

I hope that clears up your confusion.

 

[iolair]

Yes, when I first posted the question, the BBS appeared to crash, then I wanted to change the fixed 18 v to up to 18 volts, oh well!

I was checking out this a week or so ago:

http://www.freepatentsonline.com/6556778.html

Thus the questions!

In any case thanks for the explanation!

John