Method for quantifying oxygen stored in a vehicle emission control device

• US 6,694,244 B2
• Filed: 06/19/2001
• Issued: 02/17/2004
• Est. Priority Date: 06/19/2001
• Status: Expired due to Fees

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Meyer, Garth Michael, Asik, Joseph Richard
• Primary Examiner(s): Vo, Hieu T.
• Application Number:
  US09/884,751
• Publication Number:
  US 20030023368A1
• Time in Patent Office: 973 Days
• Field of Search: 701/108, 701/109, 701/114, 701/102, 602/74, 602/76, 602/78, 602/85, 602/95, 603/01, 731/181, 123/520, 123/690
• US Class Current: 701/114
• CPC Class Codes: F01N 11/00 Monitoring or diagnostic devices for exhaust-gas treatment apparatus , e.g. for catalytic activity safety, indicating or supervising devices for internal combustion engines F02B77/08; testing of machines G01M13/00
• 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 13/0097 the purifying devices are arranged in a single housing
• CPC Class Codes: F01N 2550/02 Catalytic activity of catalytic converters
• CPC Class Codes: F01N 2550/03 of sorbing activity of adsorbents or absorbents
• CPC Class Codes: F01N 2570/16 Oxygen
• CPC Class Codes: F01N 2900/0421 using an increment counter when a predetermined event occurs
• CPC Class Codes: F01N 2900/0422 measuring the elapsed time
• CPC Class Codes: F01N 3/0842 Nitrogen oxides
• CPC Class Codes: F02D 2041/389 for injecting directly into the cylinder
• CPC Class Codes: F02D 2200/0808 NOx storage capacity, i.e. maximum amount of NOx that can be stored on NOx trap
• CPC Class Codes: F02D 41/0275 the exhaust gas treating apparatus being a NOx trap or adsorbent
• CPC Class Codes: F02D 41/1441 Plural sensors
• CPC Class Codes: F02D 41/1446 the characteristics being exhaust temperatures
• 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: Y02T 10/40 Engine management systems

Abstract

A method and system are provided for determining a present value representative of the quantity of oxygen that is stored in an emission control device receiving exhaust gas generated by an internal combustion engine, as well as a present value for the maximum capacity of the device to store a selected constituent gas of the exhaust gas. The resulting values are advantageously used for adaption of predetermined values for controlling device fill and purge times when operating in an open-loop control mode, whereby open-loop device operation is optimized to reflect changes in device operating conditions.

Claims

1. A system for quantifying oxygen stored in an emission control device that receives exhaust gas generated by an internal combustion engine, wherein the device is filled with a constituent gas of the exhaust gas during a first engine operating condition and is purged of constituent gas during a second engine operating condition, the system comprising:

an oxygen sensor generating an output signal representative of a concentration of oxygen present in the exhaust flowing through the device during a sampling period; and

a control module including a microprocessor arranged to operate in a normal open-loop mode of operation by determining fill times and purge times based on engine operating conditions and corresponding values stored in a memory, wherein the control module is further arranged to periodically generate a first and second sub-optimal fill time, and determine corresponding first and second actual purge times required for purging constituent gas stored in the device during the first and second fill times, and to determine a value representative of the quantity of oxygen stored in the device as a function of both the first and second fill times, and the first and second actual purge times.

2. The system of claim 1, wherein the oxygen sensor is positioned downstream from the device.

3. The system of claim 1, wherein the oxygen sensor comprises a switching-type sensor.

4. The system of claim 1, wherein the processor is further arranged to determine a value representative of total device capacity by filling and purging the device to saturation, update at least one purge time value as a function of the quantity of oxygen value and the total capacity value.

5. A method for quantifying oxygen stored in an emission control device that receives exhaust gas generated by an internal combustion engine, wherein the device is filled with a constituent gas of the exhaust gas during a first engine operating condition and is purged of constituent gas during a second engine operating condition, the device having an optimal capacity level for storing the constituent gas, the method comprising:

periodically generating an open-loop first and second fill time, wherein the first and second fill times are different values established to cause the device to be filled to a first and second sub-optimal capacity level, respectively;

filling and purging the device based on the generated first and second fill times within a predetermined number of successive fill and purge cycles; and

for each sub-optimal fill, detecting an oxygen concentration within the flow of exhaust gas passing through the device;

generating a first and second actual purge time respectively corresponding to the first and second fill times based on the detected output signal; and

determining a value representative of the quantity of oxygen stored in the device as a function of both the first and second fill times, and the first and second actual purge times.

6. The method of claim 5, further comprising determining a value representative of current total device capacity within a predetermined number of fill and purge cycles of performing the first and second sub-optimal fill cycles, and updating at least one purge time value as a function of the quantity of oxygen value and the total capacity value.

7. The method of claim 6, wherein determining a first value representative of current total device capacity comprises:

filling the device to saturation;

purging the device;

detecting an output signal from an oxygen concentration sensor positioned downstream from the device;

generating an error signal as a function of the detected output signal and a predetermined reference value; and

determining an actual purge time necessary to purge the saturated device of substantially all constituent gas.

8. The method of claim 5, wherein detecting the oxygen concentration of the exhaust gas flowing through the device includes positioning a first oxygen sensor downstream of the device.

9. The method of claim 5, wherein the first and second purge times are generated only if steady engine speed and load conditions are detected.