Exhaust gas oxygen sensor temperature control for a variable displacement engine

• US 20020116917A1
• Filed: 03/05/2002
• Published: 08/29/2002
• Est. Priority Date: 12/07/2000
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Michelini, John Ottavio, Glugla, Christopher P.
• Granted Patent: US 6,681,563 B2
• Time in Patent Office: Days
• US Class Current: 60/285
• 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 13/107 More than one exhaust manifold or exhaust collector
• CPC Class Codes: F01N 3/101 Three-way catalysts
• CPC Class Codes: F02B 2075/184 ten
• CPC Class Codes: F02B 75/22 with cylinders in V, fan, or star arrangement
• CPC Class Codes: F02D 13/06 Cutting-out cylinders
• CPC Class Codes: F02D 17/02 Cutting-out cutting-out engines in multiple engine arrangements F02D25/04
• CPC Class Codes: F02D 41/0087 Selective cylinder activation, i.e. partial cylinder operation deceleration cut-off F02D41/123
• CPC Class Codes: F02D 41/1441 Plural sensors
• CPC Class Codes: F02D 41/1494 Control of sensor heater
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies

Abstract

A system and method for controlling temperature of an exhaust gas oxygen sensor in a system having a variable displacement engine include monitoring temperature of the sensor, comparing the sensor temperature to a corresponding desired temperature, and controlling the system to maintain the sensor temperature at or above the desired operating temperature. In one embodiment, the sensor is a heated exhaust gas oxygen (HEGO) sensor and the method includes controlling an integrated sensor heater to maintain the sensor temperature above the desired operating temperature. Depending upon the particular application, the system may also be controlled by controlling the engine to reactivate at least one deactivated cylinder to increase the temperature of the sensor alone or in combination with controlling an integrated or auxiliary sensor heater for systems using HEGO sensor(s).

Claims

1. A method for controlling an internal combustion engine having a plurality of cylinders, at least some of which are selectively deactivated in a variable displacement operating mode, and at least one exhaust gas oxygen sensor for providing an indication of oxygen content of an exhaust, the method comprising:

monitoring temperature of the at least one exhaust gas oxygen sensor; and

controlling activation of a heater associated with the at least one sensor and activation of at least one cylinder to achieve or maintain a minimum desired sensor operating temperature.

2. The method of claim 1 wherein the step of monitoring temperature comprises estimating the temperature.

3. The method of claim 1 wherein the step of monitoring temperature comprises sensing the temperature.

4. The method of claim 1 wherein the step of monitoring temperature comprises determining whether the sensor signal can be used for closed-loop air/fuel ratio control.

5. The method of claim 1 wherein the step of controlling activation of at least one cylinder comprises activating a bank of deactivated cylinders to increase the temperature of the exhaust gas oxygen sensor.

6. The method of claim 5 wherein the step of controlling activation comprises:

activating the deactivated cylinders and controlling air/fuel ratio to the cylinders during activation to provide a lean air/fuel ratio; and

controlling air/fuel ratio for a corresponding number of activated cylinders during activation of the deactivated cylinders provide a rich air/fuel ratio.

7. The method of claim 6 further comprising retarding ignition timing for the deactivated cylinders during activation.

8. A system for controlling an internal combustion engine having a plurality of cylinders, at least some of which are selectively deactivated in a variable displacement operating mode, the system comprising:

first and second upstream emission control devices;

first and second exhaust gas oxygen sensors having associated heaters and positioned upstream relative to the first and second upstream emission control devices, respectively;

at least a third emission control device positioned downstream relative to at least one of the first and second upstream emission control devices; and

an engine controller for monitoring temperature of at least one of the exhaust gas oxygen sensors and selectively controlling current supplied to the associated heater and operation in the variable displacement operating mode to achieve or maintain a desired minimum sensor operating temperature.

9. The system of claim 8 herein the engine controller monitors temperature using a temperature model.

10. The system of claim 8 wherein the controller modifies spark timing and air/fuel ratio during activation of at least one deactivated cylinder to retard spark timing from MBT timing and provide a lean air/fuel ratio relative to a stoichiometric ratio.

11. The system of claim 8 wherein the exhaust gas oxygen sensors comprise heated exhaust gas oxygen sensors with integrated heaters.

13. The apparatus method of claim 12 wherein the means for monitoring temperature comprises means for estimating the temperature.

14. The apparatus of claim 12 wherein the means for monitoring temperature comprises means for sensing the temperature.

15. The apparatus of claim 12 wherein the means for monitoring temperature comprises means for determining whether the sensor signal can be used for closed-loop air/fuel ratio control.

16. The apparatus of claim 12 wherein the means for controlling the variable displacement operating mode comprises means for activating a bank of deactivated cylinders to increase the temperature of the exhaust gas oxygen sensor.

17. The apparatus of claim 16 wherein the means for controlling the variable displacement operating mode comprises:

means for activating the deactivated cylinders and controlling air/fuel ratio to the cylinders during activation to provide a lean air/fuel ratio; and

means for controlling air/fuel ratio for a corresponding number of activated cylinders during activation of the deactivated cylinders provide a rich air/fuel ratio.

18. The apparatus of claim 17 further comprising means for retarding ignition timing for the deactivated cylinders during activation.

12. Apparatus for controlling a variable displacement internal combustion engine having a plurality of cylinders, at least some of which are selectively deactivated in a variable displacement operating mode, the apparatus comprising:

at least one exhaust gas oxygen sensor for providing an indication of oxygen content of an exhaust, the at least one exhaust gas oxygen sensor having an associated heater selectively operable to achieve or maintain a minimum desired operating temperature;

means for monitoring temperature of the at least one exhaust gas oxygen sensor;

means for controlling activation of the at least one heater associated with the at least one exhaust gas oxygen sensor; and

means for controlling the variable displacement operating mode to activate or deactivate at least one cylinder to achieve or maintain a minimum desired sensor operating temperature.