Page 111 - Methods For Monitoring And Diagnosing The Efficiency Of Catalytic Converters A Patent - oriented Survey

Toyota Motor Co. Ltd. 93

8) determining for a given time period whether the catalytic converter has deteriorated when
the relationship between the value of said ratio of the lengths and said ratio of the areas
satisfjr predetermined conditions. These conditions are:
a) the value of said ratio of the lengths is larger than or equal to a
predetermined first value, and the value of said ratio of the lengths is
smaller than said first value but larger than a predetermined second
value while the value of said ratio of the area is smaller than or equal
to a predetermined third value
b) a ratio of the value of said ratio of the lengths to the value of said
ratio of the areas is larger than a predetermined value
c) I) a ratio of the value of said ratio of the lengths to the value
of said ratio of said areas is larger than a first value; and,
II) said ratio of the lengths is larger than a second value.

normal 0: normal sensor L: length
catalyst X: deteriorated sensor A: Area
upstream downstream
sensor (1) sensor (2)
"A

\
LI : tar L2: I small small1 large
b: large
X *

L2: small medi-
4 : large lb : medium small
X
ss$t
Ll: small
4 : small $: large
X x ~
j$n, small large
LA: small L2: small
A.1 : small 4: large

Fig. 45 (from EP0547326)