Method for catalyst monitoring using flex fuel

• US 6,397,583 B1
• Filed: 03/08/2001
• Issued: 06/04/2002
• Est. Priority Date: 03/08/2001
• Status: Expired due to Fees

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Davey, Christopher K., Willette, Paul Raymond, Kluzner, Michael Igor, Jerger, Robert Joseph, Nader, David Robert
• Primary Examiner(s): Denion, Thomas
• Assistant Examiner(s): TRAN, DIEM T
• Application Number:
  US09/802,810
• Time in Patent Office: 453 Days
• Field of Search: 602/74, 602/77, 602/85
• 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 13/009 having two or more separate purifying devices arranged in series
• CPC Class Codes: F01N 13/0093 the purifying devices are of the same type
• CPC Class Codes: F01N 13/011 having two or more purifying devices arranged in parallel
• CPC Class Codes: F01N 2550/02 Catalytic activity of catalytic converters
• CPC Class Codes: F01N 2550/20 Monitoring artificially aged exhaust systems
• CPC Class Codes: F01N 3/101 Three-way catalysts
• CPC Class Codes: F02D 2200/0611 Fuel type, fuel composition or fuel quality
• CPC Class Codes: F02D 41/0007 for control of turbo-charged or super-charged engines control of the pumps per se F02B37/12
• 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 41/1495 Detection of abnormalities in the air/fuel ratio feedback system
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

Method and system are provided for monitoring performance of a catalytic converter coupled to an exhaust of an internal combustion engine supplied with fuel from a fuel tank where the fuel can include a first fuel and second fuel in concentrations that vary from one refueling to the next. A ratio indicative of catalytic converter exhaust gas conversion efficiency is determined from signals provided by an exhaust gas sensor disposed upstream and an exhaust gas sensor disposed downstream relative to the catalytic converter, and a ratio threshold value indicative of a malfunctioning catalytic converter is adjusted in dependence on the concentration of one of the first fuel and second fuel in the fuel in the fuel tank.

Claims

1. A method of monitoring performance of a catalytic converter coupled to an exhaust of an internal combustion engine supplied with fuel from a fuel tank where the fuel can include a first fuel and second fuel in concentrations that vary from one refueling to the next, comprising

a) determining a ratio indicative of catalytic converter exhaust gas conversion efficiency from signals provided by an exhaust gas sensor disposed upstream and an exhaust gas sensor disposed downstream relative to the catalytic converter, and

b) adjusting a ratio threshold value indicative of a malfunctioning catalytic converter in dependence on the concentration of one of the first fuel and second fuel in the fuel in the fuel tank.

2. The method of claim 1 wherein the first fuel comprises gasoline and the second fuel comprises ethanol.

3. The method of claim 1 wherein said ratio threshold value is adaptively adjusted based on a fuel blending ratio indicative of relative concentrations of said first fuel and said second fuel in the fuel in the tank.

4. A method of monitoring performance of a catalytic converter coupled to an exhaust of an internal combustion engine supplied with fuel from a fuel tank where the fuel can include a first fuel and second fuel in concentrations that vary from one refueling to the next, comprising

a) determining a ratio indicative of catalytic converter exhaust gas conversion efficiency from signals provided by an exhaust gas sensor disposed upstream and an exhaust gas sensor disposed downstream relative to the catalytic converter,

b) determining a fuel blending ratio indicative of relative concentrations of said first fuel and said second fuel in the fuel in the tank,

c) adaptively adjusting a ratio threshold value indicative of a malfunctioning catalytic converter in dependence on the fuel blending ratio, and

d) comparing the ratio of step a) to the adaptively adjusted ratio threshold value of step c).

5. The method of claim 4 including the further step of illuminating a malfunction indicator light when the ratio of step a) exceeds the adaptively adjusted ratio threshold value of step c).

6. The method of claim 4 repeating steps a) through d) in response to a refueling indication.

7. System for monitoring a catalytic converter coupled to an exhaust of an internal combustion engine supplied with fuel from a fuel tank where the fuel can include a first fuel and second fuel in concentrations that vary from one refueling to the next, comprising:

a) an exhaust gas sensor disposed upstream and an exhaust gas sensor disposed downstream relative to the catalytic converter, and

b) control logic in communication with said upstream exhaust gas sensor and said downstream exhaust gas sensor for determining a ratio indicative of catalytic converter exhaust gas conversion efficiency from signals provided by said exhaust gas sensor disposed upstream and said exhaust gas sensor disposed downstream relative to the catalytic converter, and

c) control logic for adjusting a ratio threshold value indicative of a malfunctioning catalytic converter in dependence on the concentration of one of the first fuel and second fuel in the fuel in the fuel tank to provide an adjusted ratio threshold value.

8. The system of claim 7 including control logic for inferring a fuel blending ratio indicative of relative concentrations of said first fuel and said second fuel in the fuel in the tank.

9. The system of claim 7 including a sensor for measuring a fuel blending ratio indicative of relative concentrations of said first fuel and said second fuel in the fuel in the tank.

10. The system of claim 7 including control logic for comparing said ratio to said adjusted ratio threshold value.

11. The system of claim 10 including control logic for illuminating a malfunction indicator light when said ratio exceeds said adjusted ratio threshold value.