PWM injector driver

[rr]

Greg Hermann wrote:

> At 12:15 PM 4/8/01, rr wrote:
> >RE: running PnH's at 24 v.
> >
> >I've thought about this. It seems as though the standard 4/1 A PnH
> >circuit would suffice. The driver dissipation would double when at the
> >hold current. Other then that it looks do-able. I'll bet that the injector
> >would open quite a bit faster.
> >
> >BobR.
> >
> Yeah, by why do it the wasteful way, and create even more heat to get rid
> of. With a switching power supply--or a pwm power device for setting the
> hold current, the heat problem gets a _LOT_ smaller, as does the power
> usage.
>
> Greg
>

Well, the wasteful way is easier with a lower parts count. Can always be used
on the bench to try it out. The PWM way adds a lot of noise to the system. I'm
not real keen on having PWM systems that close to the ECM. From a thermal
standpoint the best way is the switching p/s. Would be a complicated driver
though.

I wonder if the trace from a current probe would tell the opening of an
injector?
Can look at the slope to see when it starts to saturate. Anyone know if this can

be related to actual pintle opening?

BobR.



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