mirror of https://github.com/rusefi/rusefi.git
128 lines
3.4 KiB
C++
128 lines
3.4 KiB
C++
/*
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* @file wall_fuel.cpp
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*
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* @author Matthew Kennedy
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*/
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#include "pch.h"
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#include "wall_fuel.h"
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void WallFuel::resetWF() {
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wallFuel = 0;
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}
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floatms_t WallFuel::adjust(floatms_t desiredFuel) {
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invocationCounter++;
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if (cisnan(desiredFuel)) {
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return desiredFuel;
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}
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// disable this correction for cranking
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if (engine->rpmCalculator.isCranking()) {
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return desiredFuel;
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}
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ScopePerf perf(PE::WallFuelAdjust);
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/*
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this math is based on
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SAE 810494 by C. F. Aquino
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SAE 1999-01-0553 by Peter J Maloney
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M_cmd = commanded fuel mass (output of this function)
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desiredFuel = desired fuel mass (input to this function)
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fuelFilmMass = fuel film mass (how much is currently on the wall)
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First we compute how much fuel to command, by accounting for
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a) how much fuel will evaporate from the walls, entering the air
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b) how much fuel from the injector will hit the walls, being deposited
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Next, we compute how much fuel will be deposited on the walls. The net
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effect of these two steps is computed (some leaves walls, some is deposited)
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and stored back in fuelFilmMass.
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alpha describes the amount of fuel that REMAINS on the wall per cycle.
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It is computed as a function of the evaporation time constant (tau) and
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the time the fuel spent on the wall this cycle, (recriprocal RPM).
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beta describes the amount of fuel that hits the wall.
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TODO: these parameters, tau and beta vary with various engine parameters,
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most notably manifold pressure (as a proxy for air speed), and coolant
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temperature (as a proxy for the intake valve and runner temperature).
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TAU: decreases with increasing temperature.
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decreases with decreasing manifold pressure.
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BETA: decreases with increasing temperature.
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decreases with decreasing manifold pressure.
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*/
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// if tau is really small, we get div/0.
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// you probably meant to disable wwae.
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float tau = engineConfiguration->wwaeTau;
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if (tau < 0.01f) {
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return desiredFuel;
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}
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// Ignore really slow RPM
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int rpm = GET_RPM();
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if (rpm < 100) {
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return desiredFuel;
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}
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float alpha = expf_taylor(-120 / (rpm * tau));
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float beta = engineConfiguration->wwaeBeta;
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#if EFI_TUNER_STUDIO
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if (engineConfiguration->debugMode == DBG_KNOCK) {
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tsOutputChannels.debugFloatField1 = alpha;
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tsOutputChannels.debugFloatField2 = beta;
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}
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#endif // EFI_TUNER_STUDIO
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// If beta is larger than alpha, the system is underdamped.
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// For reasonable values {tau, beta}, this should only be possible
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// at extremely low engine speeds (<300rpm ish)
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// Clamp beta to less than alpha.
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if (beta > alpha) {
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beta = alpha;
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}
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float fuelFilmMass = wallFuel;
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float M_cmd = (desiredFuel - (1 - alpha) * fuelFilmMass) / (1 - beta);
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#if EFI_TUNER_STUDIO
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if (engineConfiguration->debugMode == DBG_KNOCK) {
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tsOutputChannels.debugFloatField3 = fuelFilmMass;
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tsOutputChannels.debugFloatField4 = M_cmd;
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}
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#endif // EFI_TUNER_STUDIO
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// We can't inject a negative amount of fuel
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// If this goes below zero we will be over-fueling slightly,
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// but that's ok.
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if (M_cmd <= 0) {
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M_cmd = 0;
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}
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// remainder on walls from last time + new from this time
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float fuelFilmMassNext = alpha * fuelFilmMass + beta * M_cmd;
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#if EFI_TUNER_STUDIO
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if (engineConfiguration->debugMode == DBG_KNOCK) {
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tsOutputChannels.debugFloatField5 = fuelFilmMassNext;
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}
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#endif // EFI_TUNER_STUDIO
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wallFuel = fuelFilmMassNext;
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wallFuelCorrection = M_cmd - desiredFuel;
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return M_cmd;
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}
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floatms_t WallFuel::getWallFuel() const {
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return wallFuel;
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}
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