Method of controlling an oxygen concentration sensor

Claim 1

A method for controlling an oxygen concentration sensor having an oxygen concentration sensing unit mounted in an exhaust system of an internal combustion engine, the oxygen concentration sensing unit including an oxygen pump element and a sensor cell element, each element being made of an oxygen ion conductive solid electrolyte and electrodes sandwiching the solid electrolyte, these elements forming a gas diffusion restriction region, a pump current supply device supplying a pump current to the electrodes of the oxygen pump element, a heater element for heating the oxygen concentration sensing unit by a heater current supplied thereto, and a heater current supply device supplying the heater current to the heater element, comprising the steps of: a first detection step for detecting a predetermined starting state of the engine; a first command step for starting the supply of the heater current from the heater current supply device to the heater element when the predetermined starting state is detected by said first detection step; a second detection step for detecting a condition when an internal resistance of the heater element is in a predetermined range after an execution of said first command step; and a second command step for starting the supply of the pump current from the pump current supply device to the oxygen pump element when said condition is detected by said second detection step.

Claim 2

A method for controlling an oxygen concentration sensor having an oxygen concentration sensing unit mounted in an exhaust system of an internal combustion engine, the oxygen concentration sensing unit including an oxygen pump element and a sensor cell element, each element being made of an oxygen ion conductive solid electrolyte and electrodes sandwiching the solid electrolyte, these elements forming a gas diffusion restriction region, a pump current supply device supplying a pump current to the electrodes of the oxygen pump element, a heater element for heating the oxygen concentration sensing unit by a heater current supplied thereto, and a heater current supply device supplying the heater current to the heater element, comprising the steps of: a first detection step for detecting a predetermined starting state of the engine; a first command step for starting the supply of the heater current from the heater current supply device to the heater element when the predetermined starting state is detected by said first detection step; a second detection step for detecting a condition when an internal resistance of the heater element is in a predetermined range after an execution of said first command step; and a second command step for starting the supply of the pump current from the pump current supply device to the oxygen pump element when said condition is detected by said second detection step.

Claim 4

A method of controlling an oxygen concentration sensor having an oxygen concentration sensing unit mounted in an exhaust system of an internal combustion engine, the oxygen concentration sensing unit including an oxygen pump element and a sensor cell element, each element being made of an oxygen ion conductive solid electrolyte and electrodes sandwiching the solid electrolyte, these elements forming a gas diffusion restriction region, a pump current supply device supplying a pump current to the electrodes of the oxygen pump element so that a voltage generated across the electrodes of the sensor cell element becomes equal to a reference voltage, a heater element for heating the oxygen concentration sensing unit by a heater current supplied thereto, and a heater current supply device supplying the heater current to the heater element, comprising the steps of: a command step for starting the supply of the pump current from the pump current supply device to the oxygen pump element; a detection step for detecting a condition when the voltage across the electrodes of the sensor cell element is in a first predetermined range and a voltage across the electrodes of the oxygen pump element is in a second predetermined range after an execution of said command step; and a judging step for judging that the oxygen concentration sensor is in an activated state when said condition is detected by said detection step.

Claim 5

A method of controlling an oxygen concentration sensor having an oxygen concentration sensing unit mounted in an exhaust system of an internal combustion engine, the oxygen concentration sensing unit including an oxygen pump element and a sensor cell element, each element being made of an oxygen ion conductive solid electrolyte and electrodes sandwiching the solid electrolyte, these elements forming a gas diffusion restriction region, a pump current supply device supplying a pump current to the electrodes of the oxygen pump element so that a voltage generated across the electrodes of the sensor cell element becomes equal to a reference voltage, a heater element for heating the oxygen concentration sensing unit by a heater current supplied thereto, and a heater current supply device supplying the heater current to the heater element, comprising the steps of: a command step for starting the supply of the pump current from the pump current supply device to the oxygen pump element; a detection step for detecting a condition when the voltage across the electrodes of the sensor cell element is in a first predetermined range and a voltage across the electrodes of the oxygen pump element is in a second predetermined range after an execution of said command step; and a judging step for judging that the oxygen concentration sensor is in an activated state when said condition is detected by said detection step.