Method of controlling an oxygen concentration sensor

• US 4,860,712 A
• Filed: 05/02/1988
• Issued: 08/29/1989
• Est. Priority Date: 07/01/1987
• Status: Expired due to Term

• Current Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Original Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Inventors: Nakajima, Toyohei, Mieno, Toshiyuki
• Primary Examiner(s): Nelli, Raymond A.
• Application Number:
  US07/189,183
• Time in Patent Office: 484 Days
• Field of Search: 123/489, 123/440, 73/23, 364/431.05, 204/1 T, 204/408, 204/412, 204/195 S, 204/425, 204/426, 204/406
• US Class Current: 123/697
• CPC Class Codes: F02D 41/1456 with sensor output signal being linear or quasi-linear with the concentration of oxygen
• CPC Class Codes: F02D 41/1476 Biasing of the sensor
• CPC Class Codes: F02D 41/1488 Inhibiting the regulation
• CPC Class Codes: F02D 41/1494 Control of sensor heater
• CPC Class Codes: G01N 27/4065 Circuit arrangements specially adapted therefor
• CPC Class Codes: G01N 27/417 using cells , i.e. more than one cell and probes with solid electrolytes

Abstract

A method for controlling an oxygen concentration sensor in which the supply of a heater current to a heater element is started when the complete combustion of the engine is detected. The supply of a pump current to an oxygen pump element is started when an internal resistance of the heater element is determined to be in a predetermined range. The supply of the pump current is started when the temperature of the oxygen pump element and the sensor cell element becomes sufficiently high to prevent the pump current from flowing excessively, thereby preventing the generation of blackening phenomenon.

Claims

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.

2. The method as claimed in claim 1, wherein said first detection step is a step for detecting that a rotational speed of the engine has exceeded a rotational speed under a complete combustion state of the engine.

3. 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.