Exhaust gas oxygen sensor temperature control for a variable displacement engine

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 lease 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, 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, wherein the step of controlling 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 to provide a rich air/fuel ratio.

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 depending on said temperature monitoring, controlling at least one of
• (a) current supplied to said heater, without activation of at least one cylinder, to achieve or maintain a minimum desired sensor operating temperature, and
• (b) current supplied to said heater and activation of at least one cylinder to achieve or maintain a minimum desired sensor operating temperature.

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, wherein the engine controller monitors temperature using a temperature model.

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 without changing the variable displacement operating mode, to achieve or maintain a minimum desired sensor operating temperature;
• and
• means for controlling activation of the at least one heater and the variable displacement operating mode to activate or deactivate at least one cylinder to achieve or maintain a minimum desired sensor operating temperature.

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, that 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;
• 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;
• 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.

An 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, 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, 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 to provide a rich air/fuel ratio.