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From: sharkey on 8 Feb 2007 17:18 Boxer <someone(a)nowhere.com> wrote: > "sharkey" <sharkey(a)zoic.org> wrote: > > > > On an EFI car, it _causes_ the fuel flow rate ... you can calculate it > > from the (fuel rail pressure - the manifold pressure) * (injector open > > time - fudge factor). > > I thought it was injection pulses That's what I mean by 'injector open time' ... the length of the pulse. Sum that up over each pulse. Multiply the whole this by the injectors' flow rate and the number of injectors and bingo! There's your fuel flow. The fudge factor is because a given injector takes a certain time to open after the pulse starts and a certain time to close after the pulse stops, and they're not always quite equal. The first term is often constantish too, because the fuel rail pressure is often regulated relative to the inlet manifold pressure. Actually, you could get relative fuel flow rate just by snooping on the injector timing, although since closed-loop EFIs wander around stoich you'd have to average it over a lot of pulses to get anything meaningful out. -----sharks -- Du verschwendest �bertragungskapazit�ten.
From: sharkey on 8 Feb 2007 17:33 Johno <varcs45(a)msn.com> wrote: > >"Nev.." <idiot(a)mindless.com> wrote in > > > snipped alot... > > >[...] > >> If it's measuring 2.68l/hr once per second that would be umm... > >> 0.0007444L/sec.. I reckon it updates about maybe 3 times per second > >> meaning it's measuring 0.00024815L/sec. I would have to check your > >> physics books to see if that is near enough to a poofteenth or not, I > >> reckon it is probably pretty damn close. > > I *know* I should know... but just how much is a poofteenth? Is is > metric / Imperial? How is it measured? An Imperial Fluid Poofteenth is a cubic Imperial beesdick, and an Imperial Poofteenth (weight) is the weight of an Imperial Fluid Poofteenth of HP Sauce at ISTP (Imperial Standard Temperature and Pressure: a bright but chilly morning in London now that Spring is here.) The Metric Poofteenth is a very small block of Platinum in a jar of pure Argon in a cafe in Paris, and you can't have it. -----sharks -- Du verschwendest �bertragungskapazit�ten.
From: sharkey on 8 Feb 2007 17:36 Dale Porter <daleaporter(a)gmail.com> wrote: > > That would be due to the air-con compressor not being driven by the engine, more the other way around. It starts up and runs at a > higher speed than the engine does at idle. It's all that heat it's pulling out of the air, it's warming up the engine and making it go faster. That's why as soon as it gets warm in Melbourne, it's winter again :-) -----snarky
From: sharkey on 8 Feb 2007 19:32 Theo Bekkers <tbekkers(a)bekkers.com.au> wrote: > > I must say I'm a little surprised that modern bikes use total waste > regulators. I haven't looked into it and most schematics would show a little > box marked regulator with no indication of what it contains or how it works. > I thought that kind of 'engineering' went out with the Triumph Zener diode. > Surely you only need to encapsulate a couple of components to make a switch > mode regulator. Otherwise you've got a 400-500 watt heater. In that size the > regulator would need to be glowing. People heat their bedrooms with that > much power. See the oscilloscope part of this thread. Modern ones do, indeed, use switchmode regulators, and it's a good reason to integrate rec and reg because the SCRs which switch in and out get to be three of the diodes. Oh I give up on ASCII art: http://zoic.org/sharkey/tmp/recreg.png All the controller needs to do is to only turn the SCRs _on_ when Vsense is too _low_. So why do they still get hot? There's still about 0.7V voltage drop across each diode/SCR, so with say 20A there'll be about 30W waste heat. A decent heatsink in free air might get 1�C/W, so on a 40�C day your regulator is running at up to 70�C. A heatsink wedged under the seat of a VFR probably gets much worse, explaining the high temperature. Semiconductor failure rates go up exponentially: diode junctions are 100x as likely to fail at 100�C as they are at 40�C. -----sharks -- Du verschwendest �bertragungskapazit�ten.
From: Peter Cremasco on 8 Feb 2007 20:43
On Fri, 9 Feb 2007 08:22:27 +1100, "Dale Porter" <daleaporter(a)gmail.com> wrote: >"Peter Cremasco" <FirstName.LastName(a)bigpond.com> wrote in message news:ms4ns2duvu4b7tvncuicr1vedevs58cnjj(a)4ax.com... > >> Strangely enough, the Camira engine speed increases when the a/c is >> switched on. I think that's the ECU overcompensating for the extra load, >> though. >> > >That would be due to the air-con compressor not being driven by the engine, more the other way around. It starts up and runs at a >higher speed than the engine does at idle. The compressor is driven by the engine, via two belts. --- Cheers PeterC [aka MildThing] '01 Yamaha FJR1300 www.dmcsc.org.au http://eladesom.com.au/ulysses/ # 37181 |