Patent US4572797A successfully refreshed from Google Patents.
EP0444783A1
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Exhaust gas catalyst monitoring
Assignee: ZF International UK Ltd
•
Filing: 1991-01-31
•
Granted: —
•
Expires: 2011-01-31
Abstract
Abstract Operation of an internal combustion engine (1) is controlled by an engine management system (8) in response to a lambda sensor (5) which monitors the oxygen content of exhaust gas flowing into a catalytic converter (4). A universal exhaust gas oxygen (UEGO) sensor (6) monitors the amount of oxygen in exhaust gas leaving the converter (4). The engine management system (8) cycles the air/fuel ratio above and below stoichiometric and the peak-to-peak amplitude of the UEGO sensor output represents the performance of the catalyst in the converter (4) such that larger amplitudes correspond to poorer performance.
Inventors
- 👤 Benjamin James Bradshaw
- 👤 Peter Geoffry Scotson
- 👤 Russell Wilson Jones
- 👤 David Williams
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-28 20:00
CPC Classifications
F; F01; F01N; F01N11/00; F01N11/007; F01N2550/00; F01N2550/02; Y; Y02; Y02T; Y02T10/00; Y02T10/10; Y02T10/40
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
76 words
A method of monitoring catalyst performance in an exhaust catalytic converter (4) of an internal combustion engine (1), comprising comparing the level of oxygen in exhaust gas entering the converter (4) with a threshold level, controlling the air/fuel ratio of the engine (1) in response to the comparison, detecting the level of oxygen in exhaust gas leaving the converter (4), and measuring the peak-to-peak value of the detected level to provide a measure of catalyst performance.
Claim 2
Dependent Claim
37 words
A method as claimed in Claim 1, characterised by repeatedly measuring the peak-to-peak value of the detected level to form a plurality of values and averaging the plurality of values to provide the measure of catalyst performance.
Claim 3
Dependent Claim
34 words
A method as claimed in Claim 1 or 2, characterised by comparing the measure of catalyst performance with a threshold value and signalling an unacceptable catalytic converter if the measure exceeds the threshold value.
Claim 4
Independent Claim
29 words
A method as claimed in any one of the preceding claims, characterised by measuring the peak-to-peak value of the detected level at each of a plurality of engine speeds.
Claim 5
Dependent Claim
27 words
A method as claimed in Claim 4 when dependent on Claim 2, characterised by repeating the measuring and averaging at each of the plurality of engine speeds.
Claim 6
Dependent Claim
32 words
A method as claimed in Claim 4 or 5 when dependent on Claim 3, characterised by comparing the measure for each of the plurality of engine speeds with a respective threshold value.
Claim 7
Independent Claim
85 words
An apparatus for monitoring catalyst performance in an exhaust gas catalytic converter of an internal combustion engine, comprising means for comparing the level of oxygen in exhaust gas entering the converter with a threshold level, means for controlling the air/fuel ratio of the engine in response to the comparing means, and means for detecting the level of oxygen in exhaust gas leaving the converter, characterised by means (12-15) for measuring the peak-to-peak value of the detected oxygen level to provide a measure of catalyst performance.
Claim 8
Dependent Claim
21 words
An apparatus as claimed in Claim 7, characterised in that the detecting means comprises a universal exhaust gas oxygen sensor (6).
Claim 9
Dependent Claim
39 words
An apparatus as claimed in Claim 7 or 8, characterised by means (17, 18) for comparing the measure of catalyst performance with a threshold value and for signalling an unacceptable catalytic converter if the measure exceeds the threshold value.
Claim 10
Independent Claim
31 words
An apparatus as claimed in any one of Claims 7 to 9, characterised by means (16) for averaging a plurality of measured peak-to-peak values to provide the measure of catalyst performance.
Claim 11
Independent Claim
55 words
An apparatus as claimed in any one of Claims 7 to 10, characterised in that the measuring means comprises a zero gradient detector (12), a gate (13) actuated by the detector (12) to pass maxima and minima from the detecting means (6), and differencing means (15) for forming the difference between the maxima and minima.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.