Method and apparatus for determining oxygen storage capacity time of a catalytic converter
First Claim
1. A method for measuring the oxygen storage capacity of a catalytic converter, comprising:
- forcing said catalytic converter into a stable saturated state, said stable saturated state corresponding to a lean air to fuel ratio;
changing said saturated state to a rich air to fuel ratio;
measuring the time delay between a first oxygen sensor and a second oxygen sensor, said first oxygen sensor being positioned at the inlet of said catalytic converter and said second oxygen sensor being positioned at an outlet of said catalytic converter;
normalizing the oxygen storage capacity to define a normalized oxygen storage capacity value; and
comparing said normalized oxygen storage capacity value to a threshold value.
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Abstract
An on-board catalyst diagnostic for monitoring the conversion efficiencies of a catalytic converter by measuring the oxygen storage capacity (OSC) of the converter. The measurement of the OSC indicates the degree of health of the converter. Under the same engine running conditions, the greater the OSC measurement, the healthier the converter. A modeled OSC is compared to the real OSC to determine a normalized OSC. The normalized OSC is compared to a predetermined threshold value in order to determine the health of the converter. The modeled OSC takes into consideration variables which will affect the value of the OSC.
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Citations
4 Claims
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1. A method for measuring the oxygen storage capacity of a catalytic converter, comprising:
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forcing said catalytic converter into a stable saturated state, said stable saturated state corresponding to a lean air to fuel ratio;
changing said saturated state to a rich air to fuel ratio;
measuring the time delay between a first oxygen sensor and a second oxygen sensor, said first oxygen sensor being positioned at the inlet of said catalytic converter and said second oxygen sensor being positioned at an outlet of said catalytic converter;
normalizing the oxygen storage capacity to define a normalized oxygen storage capacity value; and
comparing said normalized oxygen storage capacity value to a threshold value. - View Dependent Claims (2)
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3. A catalytic converter monitor apparatus, comprising:
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a first oxygen sensor mounted in a vehicle exhaust system upstream of a catalytic converter catalyst;
a second oxygen sensor mounted in the vehicle exhaust system downstream of at least a portion of the catalytic converter catalyst;
an electronic controller coupled to said first and second oxygen sensors and to a vehicle engine, said vehicle engine provides an input signal indicative of an engine operating condition to the electronic controller, wherein the electronic controller comprises;
a control algorithm, said control algorithm determining an oxygen storage capacity of said catalytic converter. - View Dependent Claims (4)
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Specification