Current/New ION information

[steve ravet]

That's an interesting article.  They show the best PPP to be around 15
degrees ATDC, over a range of RPM and load, to maximize torque.  Total
torque is the pressure integrated over the horizontal component of the
crank position, so if the burn rate of the engine varies the PPP could
also vary?

I wonder if Robert or someone else with a combustion/Heywood book can
comment on determining the best PPP  (peak pressure position, the crank
angle when max cylinder pressure is reached).

--steve

Peter Gargano wrote:
> 
> I just found this article by Ph.D. student Lars Eriksson from  Link=F6pin=
> g
> University, Sweden. The work was done in collaboration with Mecel AB and=20
> SAAB Automobile AB. It's dated 25 November 1998.
> 
> Here is the summary:
> 
>    http://www.fs.isy.liu.se/~larer/Projects/ionint.html
> 
> And here is the actual article:
> 
>    http://www.fs.isy.liu.se/~larer/Projects/main.html
> 
> Put simply, this article cites research that says maintaining the peak=20
> cylinder pressure at a particular number of degrees (after TDC) will
> maximise engine efficiency and smoothness. This point is called the peak
> pressure position (or PPP). The PPP varies with many environmental condit=
> ions
> such as inlet air temperature, humidity, etc. PPP can be estimated by mea=
> suring
> the ION current, and in particular the "shape" of the ION current. Knowin=
> g=20
> the current PPP value, the ignition timing can be varied to position the =
> peak=20
> pressure at the optimal point.=20
> 
> Perhaps a paragraph from the summary better describes the article...
> 
> >  We are studying a method for controlling the spark advance that is bas=
> ed
> >  on pattern recognition on the ionization current, in a fast inner loop=
> .=20
> >  An idealized model of the ionization current, with six parameters, is =
> fitted
> >  to the measured ionization current. Information extracted from the fit=
> ted
> >  model is then used to control the spark advance.=20
> 
> I'd recommend all interested ION project people look at this article as i=
> t
> also summarises much of the research that has been carried out to date. I=
> t
> also provides a common information database from which we can all work fr=
> om.
> 
> So, we're talking about engine optimisation, not just knock/pre-ignition
> detection!
> 
> regards,
> --=20
> Peter Gargano     mailto:peter at mail.techedge.com.au
> Ph: +61 2 6251 5519            Fax: +61 2 6251 6646