Fuel Pump speed control
Discussion
stevieturbo said:
I tested mine recently, and both pumps with the engine at idle are sitting at 21.5amps and 14.0v with 3.2bar pressure.
so your pumps are using 301W to do 3.2bar at idleMy two 044's are using a total of 53W to provide 5.7bar at idle.
When you consider that a typical claw pole alternator is only ~60% efficient, that means your engine is required to provide an extra 413W (29.5A @ 14V) or about 0.5bhp (of course, at idle, you have a few bhp spare ;-)
Steve_D said:
Would it not be easier to buy a bigger pump?
Steve
That depends on your setup.Steve
If you run a dual pump setup already with swirl tank and only needed say an extra 50-100bhp more worth of fuel from the secondary pump. Then complicating things by adding a 3rd pump when there arent really any "slightly bigger" pumps out there that arent massive.
The next step up ( IMO the next step ) might already flow double the current pump, which would then see complications with the primary pump.
Then in that instance it isnt easier. An extra 2-3volts as and when required will do the job quite well.
It's far more popular in the US than UK though. And I'll say that for a long time I thought it as a bodge. But on the same note, I also seen pump speed controllers as a waste of money too.
Ive came to rethink both of those ideas. Both have very valid applications.
As my pump controller does "synchronous rectifiation" on it's PWM output signal (in order to limit resistive losses and hence temperature rise during high current operation) you could simply add an external inductor, jack up the PWM frequecy (approx 100kHz) and use it as a "buck/boost" convertor. Finger in the air educated guess would suggest that an inductor with 2/3 of the pump's series resistance would be possible, and hence giving approx 1/3 voltage boost to the pump.
But, that system would probably weigh/package the same as an additional pump, which also gives you some extra reliability/limp home capability.
I also suspect, that in reality most peoples exisiting pump set up, which when used with a return system are "on the edge" with regard to flow capability would probably be fine with a returnless system. (because you don't need ANY return flow to make your pressure regulator generate enough of a restriction to actually produce the desired fuel rail pressure (and also because hydraulic losses in the return line are eliminated)
But, that system would probably weigh/package the same as an additional pump, which also gives you some extra reliability/limp home capability.
I also suspect, that in reality most peoples exisiting pump set up, which when used with a return system are "on the edge" with regard to flow capability would probably be fine with a returnless system. (because you don't need ANY return flow to make your pressure regulator generate enough of a restriction to actually produce the desired fuel rail pressure (and also because hydraulic losses in the return line are eliminated)
MarkWebb said:
So where are we with this? I am waiting patiently at the back of the queue as instructed by Steve but it does not seem to be moving! I want to fit something before the spring if possible?
Well, the prototype unit is installed and running in my rally/track car, and i had hoped to get some mileage onto it before considering offering the unit to anyone else. Unfortunately various work commitments that i have been unable to turn down (mainly due to being offered an almost unseamly amount of cash for doing very little... ;-) have meant little running time has been acrude to date.MarkWebb said:
I am hunting all over the world for a fuel pump speed controller that works. Many people say that they are on the cusp of producing something. Nobody except the OEMs yet seems to have a working system.
What is the problem here Mr Max Torque?
I dont think there is anything difficult about a simple controller. Aeromotive offer a basic one, and I think there are others.What is the problem here Mr Max Torque?
If you google, there are quite a few high current PWM controllers about. But most seem to base their output on a resistive input.
A very simple ecu controlled controller would be PWM in, and high current PWM out.
Not sure if anything like that does exist ? Or if the resistance based PWM controllers could be adapted to accept a PWM input from an ecu.
What do you want to use as a primary control parameter Mark? If you can add a rail pressure sensor, and tap into your map sensor, then my system will work fine on your engine. However, i have not yet had a chance to fully prove it out to my normal thorough fashion! (it works fine, control rail pressure to target perfectly, drives 1 lift pump and 2 pressure pumps, but i havn't got the test miles on the system i would like to have before claiming it was "production ready" etc
Max_Torque said:
What do you want to use as a primary control parameter Mark? If you can add a rail pressure sensor, and tap into your map sensor, then my system will work fine on your engine. However, i have not yet had a chance to fully prove it out to my normal thorough fashion! (it works fine, control rail pressure to target perfectly, drives 1 lift pump and 2 pressure pumps, but i havn't got the test miles on the system i would like to have before claiming it was "production ready" etc
Are you aware of any basic PWM controllers that could be driven off an ecu PWM ?For a nice simple setup
Max_Torque said:
My system will quite happily act as a "pwm follower", but it seems a bit of a waste to install an expenise pwm controller and just use it as a dumb slave?
When googling a few days ago, I did find a few relatively cheap controllers. Ive no idea how these work, or how they could be adapted though. Electronics are not my thing, although I do have a basic understanding.And I'm sure many other potential users are in the same boat. But they might still want a high fuel flow capacity at max demand, and a low fuel flow capacity at low demand.
And to be able to achieve this in a very easy to install, and very easy to control manner.
A simple PWM follower as you call it, would probably satisfy 80% of users. And I dont see it as a waste, when it will be doing what the user wants. ie reducing the fuel pumps output during low demand.
And as many of the DIY controllers I found, or some from China etc were based on DC motor control. They could also be used for other applications, not just fuel pumps.
But again, most I found seem to use a resistance as their input
eg
http://www.virtualvillage.co.uk/12v-30a-pwm-dc-mot...
http://www.ebay.co.uk/itm/PWM-HHO-Controller-DC12-...
http://www.ebay.com/sch/Speed-Controls-/71393/i.ht...
Edited by stevieturbo on Thursday 8th December 22:17
A basic single bridge PWM controller for a brushed motor (like a conventional fuel pump) can be adapted to read a PWM input easily enough. They usually read in a voltage that is supplied by a potential divider. They have 3 wires normal for the speed signal:
1) 5v
2) signal
3) 0v
By placing a variable resisitor with the wiper varying it's position between the 5v and 0v end of the potentiometer you are effectively returning a variable voltage, which the device uses as it's input signal.
Now a PWM signal can also be used to create a varying voltage, you just need to "low pass filter" the pwm frequency (resistor in series, capacitor in parallel), this will generate an output voltage proportional to the pwm duty cycle. The only important bit is to ensure that the pwm "high" voltage is the same as the maximum expected by the amplifier device. (alternately, use the pwm to switch a simple transistor that effectively "Chops up" the normal output voltage provided by the amplifier.
The thing about true automotove rated electronics is that the environment is pretty nasty, with voltage spikes, ripples, load dump events, and a harsh mechanical environment (damp, vibration, heat, cold etc)
My triple channel pwm driver works perfectly, but without further testing i would hesitate to sell it to someone (whom then might be let down by it due to it operating in an enviroment i had not yet tested it for etc)
1) 5v
2) signal
3) 0v
By placing a variable resisitor with the wiper varying it's position between the 5v and 0v end of the potentiometer you are effectively returning a variable voltage, which the device uses as it's input signal.
Now a PWM signal can also be used to create a varying voltage, you just need to "low pass filter" the pwm frequency (resistor in series, capacitor in parallel), this will generate an output voltage proportional to the pwm duty cycle. The only important bit is to ensure that the pwm "high" voltage is the same as the maximum expected by the amplifier device. (alternately, use the pwm to switch a simple transistor that effectively "Chops up" the normal output voltage provided by the amplifier.
The thing about true automotove rated electronics is that the environment is pretty nasty, with voltage spikes, ripples, load dump events, and a harsh mechanical environment (damp, vibration, heat, cold etc)
My triple channel pwm driver works perfectly, but without further testing i would hesitate to sell it to someone (whom then might be let down by it due to it operating in an enviroment i had not yet tested it for etc)
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