Injector Driver Module

Don.F.Broadus at ucm.com Don.F.Broadus at ucm.com
Mon Aug 10 21:28:39 GMT 1998


Jose'  Thanks for the info you have posted, I need all the help I can get
with my driver project.

	-----Original Message-----
	From:	Jose  Rodriguez [SMTP:JRodriguez at impcotechnologies.com]
	Sent:	Monday, August 10, 1998 2:22 PM
	To:	DIY_EFI at efi332.eng.ohio-state.edu
	Subject:	Re: Injector Driver Module

	Don, thanks for your reply.

	  I am going to fire them sequentially, like you indicate below.
Yes, I also see that the factory heatsinks on the driver transistors are not
big, and that is what surprises me.
	  The only explanation I have so far is that the injectors used by
the OEM modules are the saturated type (16 ohms, and the driver is not
working on the linear region, but saturated, and hence very little power is
dissipated there). Unfortunately, I need to drive peak-and-hold injectors
(1.5..2.3 ohms).
	  Over the 360 crank degrees, the injectors will be fired
approximately like this:
	#1 (0 degrees), #8 (45 deg), #4 (90), #3 (135), #6 (180), #5 (225),
#7 (270), #2 (315).

	  Every driver would be on up to 85% of the time, so no matter what
the timing sequence is, every power driver will conduct the Hold current (1
amp) for 85% of the time, so the average power dissipated on the driver
module box is:
	  [ (Battery Voltage)-(Hold Current)*(Coil Resistance) ]*(Hold
Current)*(Duty Cycle)*(number of injectors) =
	  so assuming worst case (Maximum battery voltage):
	  [ (16)-(1)*(1.5) ]*(1)*(0.85)*(8) = 98.6W!

	  How much power is being dissipated in your module?

	>>> <Don.F.Broadus at ucm.com> 08/10/98 10:47AM >>>
	I'm working on an  injector driving module also. If you are going to
fire
	the injectors sequentially, then one injector would be on at a time
in the
	firing order sequence (1-8-4-3-6-5-7-2 GM V-8)  If you are going to
batch
	<snip>



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