Henry Nee came up with a great idea. If we standardize on a spreed sheet
format for
the mixture map we can share (even across programs). Yours and mine.
This is the megasquirt format.
It is broken down into 8 RPM's and 8 manifold pressures.
Usually EFI programmers interpolate between these values.
Keven, Please do this. It will help other people greatly.
The idea is to be able to dump the table to a PC through the USB and edit
it in the
PC as necessary. Then reload it back into the chip.
This is how it is done in Megasquirt.
These are median values so they can go down to zero and up to 255 as
necessary.
They are also a function of the injector used. If you find that the values
are all on
the high side you could go up on the injection pressure or use larger
injectors.
Same vice versa.
Tracy uses two staged injectors per rotor so there could be one table for
each
injector. The tables only require 65 bytes of flash memory each.
I am using one computer per rotor.
Paul Lamar
I was looking into that earlier- trying to get some known figures for a
map. The MegaTune software doesn't cooperate without a MS controller
attached to the computer, so that didn't work so well.
The stock CAS turns at half engine speed, so I wouldn't have to remove a
tit, just add a pickup 90 degrees from the first. This would fire rotor 1
and 2 in succession. This eliminates the synchronization issue, in that
each rotor would be fired from its own mag pickup.
I plan to map a table for the MAP sensor, and for the injectors too. A map
is easier than a formula in most cases. However, this table can't
compensate for the additional enrichment of the mixture during takeoff, and
then switch to the lean mixture for cruise. And we have to deal with the
difference in temperature at takeoff location and altitude, cruise altitude
and location, and landing elevation and location. I have left S FL with it
nice and sunny, close to 80 to run into temps -7C at cruise over Savannah,
then to land at elevation 130 at 34 degrees and drizzle. Quite a difference
to be compensated for. I have temperature sensors for ambient and will pick
up another one for intake air temp (turbo). I will have to compensate
somehow for the intake temp I am sure. Since normally air density can be
calculated based on pressure, I can add a table for temperature
compensation, but that just adds another layer of programming. Another way
of doing this would be by using a thermistor- the system could read the
thermistor and automatically compensate for the temperature of the intake
charge. This reduces pilot workload, and the pilot could still adjust the
mixture manually from inside the cockpit- maybe.
I am still looking for the solution to the manual leaning issue- the
lawmower EFI code that I posted dealt with the PWM through a variable
resistor- a pot. Based on how the engine was running he would lean the pot
and change the mixture. This could be done through a pot, or through
interrupts with a segmented wheel. The pot would be easier. I want to
couple the thermistor and the pot to alter the PWM within limits to
enrichen or lean the mixture.
A base pulse width for the standard 550 Mazda injector at idle and WOT
would be helpful if anyone has this info.
Kevin Alderman
Your not synced when you do that. You need to know when it is rotor one or
rotor two and 22 degrees BTDC for each.
The rotors are 180 degrees out of phase. You need a pick up for rotor one and another
pick up for rotor 2. The second gen and all other later Mazda's get the 2 rotor
firing time mathematical from the software. That takes processor time and a lot of
software.
I am going to use two hall effect sensor side by side and have two magnets 180 out
phase on a wheel but displaced fore and aft. One for the front rotor and one for the
rear rotor. Three magnets and three hall effect sensors for a 3 rotor.
This saves the hard part in software and the ignition can stand alone with the 2nd
gen coils if they trigger 22 degrees BTDC. No advance as the racers say it is not needed.
Paul Lamar
--
The Rotary Engine News Letter. Powered by Linux.
ACRE NL web site.
http://www.rotaryeng.net
You Tube key word PaulLamar2
Copyright 1998-2012 All world wide rights reserved.
