Injector Driver Module

[Don.F.Broadus at ucm.com]

Orin,  According to  Haynes techbook, fuel injection 1986-1996 (10220) "The
duty cycle is the ratio of injector on- time to total on-and- off time. In
other words, it's a variable % of one complete injector operating cycle" .
2msec on 1msec off
Equals  3msec total injector time 2/3= 66% duty cycle.  At high RPM the
Pulse width (on time) will  be  say 10 to 20 msec then off about 5 msec  20
+5 = 25  complete cycle. 20 msec on time / 25 = 80% duty cycle . We need to
know what rpm and what pulse width the on-off times will be. I still believe
the switching transistors voltage drop (Vsat)  Frequency of operation  and
current through the transistor will give you the heat that needs to be heat
sinked. 

 
Just my .02 cents
                               
 
Don 





	-----Original Message-----
	From:	Orin Eman [SMTP:orin at wolfenet.com]
	Sent:	Monday, August 10, 1998 3:23 PM
	To:	diy_efi at efi332.eng.ohio-state.edu
	Subject:	Re: Injector Driver Module


	> Then only 4 would be on at a time.  The factory heat sinks on the
driver
	> transistors are not that big so I doubt that the power dissipated
is very
	> high.  The duty cycle is a combination of on time and off time, so
even at
	> 85% the injector would
	> Only be on for less than half of the time. The frequency of the
injector
	> pulse needs to be known, at 6000 rpm the ignition

	Nope, sorry, 85% duty cycle means on 85% of the time, off 15% of the
time.

	Orin.