Catalytic converter efficiency monitor
First Claim
1. A method for monitoring efficiency of a catalytic converter in a motor vehicle, said method comprising the steps of:
- operating an engine under a closed loop condition;
determining if at least one preestablished condition is met for monitoring the efficiency of the catalytic converter;
determining whether the engine has stabilized if the at least one preestablished condition is met;
combining a square wave multiplier signal with a feedback multiplier signal if the engine has stabilized;
counting a number of square wave edges of the combined signal for an upstream oxygen sensor positioned upstream of the catalytic converter;
counting a number of switches of a signal across a predetermined switch point from a downstream oxygen sensor positioned downstream of the catalytic converter;
calculating a switching frequency ratio based on the count of square wave edges and oxygen sensor switches; and
using the switching frequency ratio to establish the efficiency level of the catalytic converter.
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Accused Products
Abstract
A method of monitoring efficiency of a catalytic converter in a motor vehicle includes the steps of determining if at least one predetermined condition is met for monitoring the efficiency of the catalytic converter and combining a square wave multiplier signal with a feedback multiplier signal if the at least one predetermined condition is met. The method includes counting a number of square wave edges of the combined signal for an upstream oxygen sensor positioned upstream of the catalytic converter and counting a number of switches of a signal across a predetermined switch point from a downstream oxygen sensor positioned downstream of the catalytic converter. The method also includes the steps of calculating a switching frequency ratio based on the count of square wave edges and oxygen sensor switches and using the switching frequency ratio to establish the efficiency level of the catalytic converter.
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Citations
11 Claims
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1. A method for monitoring efficiency of a catalytic converter in a motor vehicle, said method comprising the steps of:
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operating an engine under a closed loop condition; determining if at least one preestablished condition is met for monitoring the efficiency of the catalytic converter; determining whether the engine has stabilized if the at least one preestablished condition is met; combining a square wave multiplier signal with a feedback multiplier signal if the engine has stabilized; counting a number of square wave edges of the combined signal for an upstream oxygen sensor positioned upstream of the catalytic converter; counting a number of switches of a signal across a predetermined switch point from a downstream oxygen sensor positioned downstream of the catalytic converter; calculating a switching frequency ratio based on the count of square wave edges and oxygen sensor switches; and using the switching frequency ratio to establish the efficiency level of the catalytic converter. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method for monitoring efficiency of a catalytic converter in a motor vehicle having an internal combustion engine, said method comprising the steps:
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operating an engine under a closed loop condition; determining if at least one predetermined condition is met for monitoring the efficiency of the catalytic converter; determining whether the engine has stabilized if the at least one preestablished condition is met; combining a square wave multiplier signal with a feedback multiplier signal if the engine has stabilized; counting a number of square wave edges of the combined signal for an upstream oxygen sensor positioned upstream of the catalytic converter; counting a number of switches of a signal across a predetermined switch point from a downstream oxygen sensor positioned downstream of the catalytic converter; calculating a switching frequency ratio based on the count of the square wave edges and oxygen sensor switches; determining if the switching frequency ratio is greater than a predetermined level; concluding that the catalytic converter is efficient if the switching frequency ratio is less than the predetermined level; and concluding that the catalytic converter is not efficient if the switching frequency ratio is greater than the predetermined level. - View Dependent Claims (9, 10, 11)
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Specification