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The mkiv Supra Owners Club

Injector Duty Cycle


Graham Rudd

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I want to make a device to measure the duty cycle of an injector but I'm not 100% certain of how the duty cycle is measured, I *think* I know, but lets make sure.

 

To get the duty cycle percentage is it as simple as measuring the pulse width and dividing by the pulse width + the time until the next pulse? Or is there some subtlety I'm missing?

 

 

i.e.                                                 pulse width

       duty cycle%  =                       ---------------

                             pulse width + time measured until next pulse

 

 

Any help would be much appreciated. If anyone has any good links to technical articles on this kind of thing then that would be fantastic.

 

Many thanks,

Graham

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Yep, Pete already does one, so I'm hoping he wanders into this thread and has the patience to answer. ;)

 

I don't really want to ask him directly as he might find these questions (very simple questions from his perspective) a little tedious. :)

 

 

Graham

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Duty Cycle = Pulse Width on ON period (s)

                   ---------------------------------            X 100%

                   Period (s)

 

Where Period is the time between two +ve rising edges (or two -ve falling edges, either will do)

 

Duty cycle is the ratio of the ON period with respect to the total period of the waveform.

 

 

So if the injectors are being pulsed at 1000Hz then the period is 1/1000 = 1ms and if they are on for 0.5ms then the Duty Cycle is obviously 0.5ms /1ms *100% = 50%

 

Similarly if they are on for 0.20ms and the period is 0.5ms ( then the duty cycle is 40%)

 

 

See http://www.trlperformance.com/afri.html

 

regards

Pete

 

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