Exhaust gas recirculation monitor

• US 6,257,214 B1
• Filed: 02/03/2000
• Issued: 07/10/2001
• Est. Priority Date: 02/03/2000
• Status: Expired due to Fees

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Bidner, David Karl, Martin, Douglas Raymond, Cullen, Michael John
• Primary Examiner(s): Dolinar, Andrew M.
• Assistant Examiner(s): Castro, Arnold
• Application Number:
  US09/498,130
• Time in Patent Office: 523 Days
• Field of Search: 123/568.16, 731/173, 731/181
• US Class Current: 123/568.16
• CPC Class Codes: F02D 2200/0406 Intake manifold pressure
• CPC Class Codes: F02D 41/0055 Special engine operating conditions, e.g. for regeneration of exhaust gas treatment apparatus
• CPC Class Codes: F02M 26/49 Detecting, diagnosing or indicating an abnormal function of the EGR system
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

An EGR system monitor combines an inferred manifold absolute pressure based on measured mass air flow with a measured manifold absolute pressure to obtain a more complete system response during a test procedure involving the opening and closing of the EGR valve.

Claims

1. A method of monitoring the integrity of an EGR system of an automotive engine having an intake manifold and an exhaust manifold interconnected by an EGR line for recirculating exhaust gas to said intake manifold through an EGR valve located in said EGR line, comprising a sequence of the following steps:

determining first pressure values based on measured manifold absolute pressure and inferred manifold absolute pressure when said EGR valve is open;

determining second pressure values based on measured manifold absolute pressure and inferred manifold absolute pressure when said EGR valve is closed;

determining a difference pressure value based on the difference between said first and second pressure values;

making a decision on the integrity of the EGR system based on said difference pressure value.

2. The method of claim 1 wherein said inferred manifold absolute pressure is based on measured mass air flow to said intake manifold.

3. The method of claim 2 wherein said difference pressure value is the difference between the average of said first and second pressure values over N measurement cycles.

4. The method of claim 2 wherein said difference pressure value is the average of the difference between the sum of measured and inferred pressure values at said open and closed positions;

and wherein said decision on the integrity of the EGR system is based on said average.

5. A system for monitoring the integrity of an EGR system of an automotive engine, comprising:

an EGR line interconnecting an intake manifold and an exhaust manifold of said engine for recirculating exhaust gas to said intake manifold through an EGR valve located in said EGR line;

an engine controller for receiving inputs from a plurality of sensors and for positioning said EGR valve to open and closed positions;

an air mass meter for measuring mass air flow to said intake manifold;

an manifold absolute pressure sensor for measuring the pressure at said intake manifold;

said controller storing measured values of pressure from said sensor and inferred values of pressure based on mass air flow from said meter at both said open and closed positions of said EGR valve and computing an average difference pressure value based on the difference between the sum of measured and inferred pressure values at said open and closed positions;

said controller making a decision on the integrity of the EGR system based on said difference pressure value.

6. A method of monitoring the integrity of an EGR system of an automotive engine having an intake manifold and an exhaust manifold interconnected by an EGR line for recirculating exhaust gas to said intake manifold through an EGR valve located in said EGR line, comprising a sequence of the following steps:

measuring manifold absolute pressure and mass air flow in said intake manifold when the EGR valve is open;

measuring manifold absolute pressure and mass air flow in said intake manifold when the EGR valve is closed;

inferring manifold absolute pressure from the measured mass air flow when the EGR valve is open and when the EGR valve is closed;

determining the difference in measured manifold absolute pressure when the EGR valve is open and when the EGR valve is closed;

determining the difference in inferred manifold absolute pressure when the EGR valve is open and when the EGR valve is closed;

averaging the difference in measured manifold absolute pressure over N measurement cycles;

averaging the difference of inferred manifold absolute pressure over said N measurement cycles;

comparing the sum of the values obtained by averaging the measured and inferred manifold absolute pressures with a threshold pressure value in order to make a decision on the integrity of the EGR system.