On-board diagnostic catalyst monitoring system

• US 6,532,734 B1
• Filed: 02/01/2002
• Issued: 03/18/2003
• Est. Priority Date: 02/01/2002
• Status: Expired due to Fees

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Kluzner, Michael Igor, Uhrich, Michael James, Shane, Michael Daniel, Jerger, Robert Joseph, Nader, David Robert
• Primary Examiner(s): Denion, Thomas
• Assistant Examiner(s): Tran, Binh
• Application Number:
  US10/062,384
• Time in Patent Office: 410 Days
• Field of Search: 602/74, 602/76, 602/77, 602/85, 701/102, 701/109
• US Class Current: 60/277
• CPC Class Codes: F01N 11/007 the diagnostic devices measuring oxygen or air concentration downstream of the exhaust apparatus
• CPC Class Codes: F01N 2550/02 Catalytic activity of catalytic converters
• CPC Class Codes: F02D 2200/0404 Throttle position
• CPC Class Codes: F02D 2200/0802 Temperature of the exhaust gas treatment apparatus
• CPC Class Codes: F02D 41/1441 Plural sensors
• CPC Class Codes: F02D 41/1456 with sensor output signal being linear or quasi-linear with the concentration of oxygen
• CPC Class Codes: F02D 41/1474 by detecting the commutation time of the sensor
• CPC Class Codes: F02D 41/1495 Detection of abnormalities in the air/fuel ratio feedback system
• CPC Class Codes: F02D 41/187 using a hot wire flow sensor
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

A method for determining the effectiveness of a catalyst having both first, relatively high oxidizable material provided to remove emissions from the exhaust of an internal combustion engine and a second, relatively low oxidizable material provided to remove emissions from such exhaust. The method includes measure a difference in oxygen content upstream and downstream of the catalyst while the engine is producing the exhaust to determine the effectiveness of the first material and determining the effectiveness of the second material by comparing time delay in a property of the exhaust as such exhaust passes through the catalyst. In one embodiment, the property of the exhaust is the oxygen content in such exhaust. In one embodiment, the effectiveness of the second material is measured after the first material is determined to be ineffective.

Claims

1. A method for determining the effectiveness of a catalyst having both first, relatively high oxidizable material provided to remove emissions from the exhaust of an internal combustion engine and a second, relatively low oxidizable material provided to remove emissions from such exhaust, such method comprising:

measuring a difference in oxygen content upstream and downstream of the catalyst while the engine is producing the exhaust to determine the effectiveness of the first material; and

determining the effectiveness of the second material by comparing time delay in a property of the exhaust as such exhaust passes through the catalyst.

2. The method recited in claim 1 wherein the property of the exhaust is oxygen content.

3. The method recited in claim 2 wherein the effectiveness of the second material is measured after the first material is determined to be ineffective.

4. A method for monitoring efficiency of a catalytic converter during operation of an internal combustion engine coupled to the catalytic converter as exhaust from the engine passes through such converter, such method comprising:

measuring an upstream time history of oxygen content of the exhaust upstream of the converter and a downstream time history of oxygen content of the exhaust downstream of the converter;

determining a difference in such measured amplitudes;

determining when the determined difference is less than a predetermined value indicating potential ineffectiveness of the converter;

measuring a time delay between the upstream time history and the downstream time history; and

comparing the determined time delay with a reference time delay to determine the efficiency of the converter, such converter being determined to be ineffective if the converter has been determined to be potentially ineffective and the time delay is less than the reference time delay.

5. The method recited in claim 4 wherein the predetermined value is between two operating stoichiometric ratios.

6. The method recited in claim 5 wherein the converter includes an oxidizable material and a precious metal material.

7. A method for monitoring efficiency of a catalytic converter having a relatively highly oxidizable material to react with products in the exhaust and a relatively less oxidizable material to react with products in the exhaust as exhaust from the engine passes through such converter, such method comprising:

measuring an upstream time history of a first property of the exhaust upstream of the converter and a downstream time history of the first property of the exhaust downstream of the converter;

determining when the measured upstream first property and the measured downstream first property differ by a first predetermined value indicating potential ineffectiveness of the converter;

measuring an upstream time history of a second property of the exhaust upstream of the converter and a downstream time history of the second property of the exhaust downstream of the converter;

determining when the measured upstream second property and the measured downstream second property differ by a second predetermined value;

determining when the measured upstream second and the measured downstream second property differ by a second predetermined value;

determining the ineffectiveness if the catalyst has been determined to be potentially ineffective and the measured upstream second and the measured downstream second property differ by the second predetermined value.

8. A method for determining degradation of a catalyst communicating with exhaust gases from said engine, said catalyst having first and second oxidizable materials removing emissions from said exhaust gases, said method including:

measuring a difference in oxygen content upstream and downstream of said catalyst while said engine is producing said exhaust gases to determine when said first oxidizable material is degraded;

measuring a time delay in a property of said exhaust gases as said gases pass through said catalyst to determine when said second oxidizable material is degraded; and

,

indicating said catalyst is degraded when said first and second oxidizable materials are degraded.