Catalyst monitoring using ego sensors
First Claim
1. A method of detecting malfunction or degradation of a primary gas mixture equilibrator, such as a device to fully catalytically convert substantially all exhaust gases of a flow, by the steps of:
- (a) placing a pair of oxygen sensors in a common flow of gases exiting from said gas mixture equilibrator at essentially the same location to provide a pair of signals, said sensors differing in that one sensor has an electrode, exposed to such flow, which is designated to be substantially more catalytic than the design of the other sensor electrode exposed to such flow; and
(b) determining if there is a predetermined difference between the signals of said sensors, indicating that the sensor having a more catalytic design was able to more fully equilibrate the flow, such difference meaning there is malfunction or degradation of the primary equilibrator.
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Accused Products
Abstract
A method of monitoring, while on board an automotive vehicle, one or more of catalyst performance, engine misfire, and combustion quality, the vehicle having an internal combustion engine equipped with a catalyst for converting noxious emissions of the engine, comprising: (i) exposing at least one pair of EGO sensors to substantially the same emissions either exiting from the engine or from the catalyst, one of the EGO sensors having its electrode highly catalytic, and the other sensor having its electrode low-to-noncatalytic; (ii) comparing the outputs of the sensor electrodes (amplitude, frequency, or phase shift) to determine if there is a sufficient differential to indicate a misfire or poor combustion in the case of the sensors being located downstream of the engine exhaust but upstream of the catalyst, or indicating poor catalyst efficiency in the case of the sensors being placed substantially immediately downstream of the catalyst. The catalyst may be a three-way catalyst (or an oxidation catalyst). The sensors may be of the EGO, HEGO, or UEGO types. Two pairs of sensors may be used, a first pair being placed substantially immediately upstream of the catalyst and the second pair being placed substantially immediately downstream of the catalyst, the pairs of EGO sensors being incorporated into a closed-loop feedback control of the engine fuel control system.
40 Citations
24 Claims
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1. A method of detecting malfunction or degradation of a primary gas mixture equilibrator, such as a device to fully catalytically convert substantially all exhaust gases of a flow, by the steps of:
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(a) placing a pair of oxygen sensors in a common flow of gases exiting from said gas mixture equilibrator at essentially the same location to provide a pair of signals, said sensors differing in that one sensor has an electrode, exposed to such flow, which is designated to be substantially more catalytic than the design of the other sensor electrode exposed to such flow; and (b) determining if there is a predetermined difference between the signals of said sensors, indicating that the sensor having a more catalytic design was able to more fully equilibrate the flow, such difference meaning there is malfunction or degradation of the primary equilibrator. - View Dependent Claims (2, 3)
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4. A method of detecting a difference in oxygen partial pressure between equilibrated and nonequilibrated exhaust gases from one selected from the group of an engine and a main conversion catalyst, comprising:
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(a) placing differentially catalyzed electrodes of one or more oxygen sensors in a locale selected from the group of (i) same locale of exhaust gases downstream of said engine but upstream of said engine, and (ii) same locale of exhaust gases downstream of said catalyst, to generate a pair of signals; and (b) comparing signals generated by each of said electrodes and, if a predetermined sufficient difference is present, make indication respectively of engine malfunction of catalyst degradation. - View Dependent Claims (5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. A method of on-board monitoring of an automotive vehicle having an internal combustion engine generating emissions and a catalyst through which such emissions flow, said monitoring being of one or more catalyst performance, engine misfire, and combustion quality, the method comprising the steps of:
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(a) exposing at least a first pair of EGO sensors to one and the same portion of said emissions exiting from said catalyst to generate a pair of outputs, said first pair of EGO sensors having one sensor with an electrode highly catalytic and having the other sensor with an electrode low-to-noncatalytic, and exposing at least a second pair of EGO sensors to one and the same portions of said emissions that enter the catalyst to generate another pair of outputs, said second pair having one sensor with an electrode highly catalytic and having the other sensor with an electrode low-to-noncatalytic; and (b) continuously rapidly comparing said outputs of one sensor with the other sensor of each pair to determine if there is a sufficient difference to indicate a misfire or poor combustion in the case of the second pair of sensors located upstream of the catalyst, and indicating poor catalyst efficiency in the case of the first pair of sensors located downstream of the catalyst. - View Dependent Claims (23, 24)
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Specification