Page 247 - Methods For Monitoring And Diagnosing The Efficiency Of Catalytic Converters A Patent - oriented Survey
P. 247
Other Methods 229
and on the flux of gas that flows through the converter. More specifically the values (Ox,
Red) are calculated by making use of the following formulas:
if v>O: Ox=v//K and Red = 0
if v< 0: ox = 0 and Red = -v / K ’
where:
K and K’ are characteristic parameters of the downstream oxygen sensor.
The chemical kinetics (clr c2) of the reactions are calculated by making use of the
following formulas:
C2
c2 -= k2 (0.5~ x)~~ (x, y, v)
f
~
where:
kl, al, bl and k2, a2, b2 are the characteristic parameters of the two reactions
5) estimating the concentration (2) of the oxygen downstream of the catalytic converter by
writing the low of variation of (z) in time:
dddt = - K% /z(t) - I@)] i (K12e) /C1(x, y, I.’) - C2(x, y, I.’)]
where:
L is the length of the catalytic monolith
e is the void fraction of the monolith
6) estimating the quantity of oxygen (x) stored in the converter by means of the formula:
7) calculating the value of (y) by taking into account the difference of the measured (v) and
calculated value (2) of oxygen content in the exhaust gas. The following formula is used:
