Test method for verifying correct matching of an exhaust gas oxygen sensor and a vehicle engine

• US 6,604,007 B2
• Filed: 03/19/2001
• Issued: 08/05/2003
• Est. Priority Date: 03/19/2001
• Status: Expired due to Fees

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: General Motors Corporation (Motors Liquidation Co. GUC Trust)
• Inventors: Morgan, William J., Leven, Martin
• Primary Examiner(s): Follansbee, John
• Assistant Examiner(s): Hartman, Jr., Ronald D.
• Application Number:
  US09/810,047
• Publication Number:
  US 20020133242A1
• Time in Patent Office: 869 Days
• Field of Search: 700/32, 700/79, 700/75, 701/29, 701/101, 702/113, 702/116
• US Class Current: 700/79
• CPC Class Codes: F02D 41/3005 Details not otherwise provided for
• CPC Class Codes: G01M 15/104 using oxygen or lambda-sensors testing catalytic converters F01N3/18, F01N11/007

Abstract

An improved assembly method and a corresponding diagnostic method carried out by an electronic engine control module in a factory test setting reliably and inexpensively verifies correct matching of a vehicle engine and an exhaust gas oxygen sensor installed on an exhaust pipe thereof. Heating elements within the oxygen sensors are manufactured so as to exhibit an electrical resistance that is different for each type of sensor. Due to normal part-to-part tolerance variation, the heater resistance of one type of oxygen sensor falls into a first range, and the heater resistance of the other type of oxygen sensor falls into a second range. The electronic control module for each engine is calibrated as part of its overall fuel control calibration, to recognize an oxygen sensor current requirement range corresponding to the respective fuel control (i.e., leaded or unleaded). The electronic control module operates during an initial period of engine operation during factory testing prior to convergence of the first and second resistance ranges to measure the average current supplied to the installed oxygen sensor, and to compare the measured current with the calibrated current requirement range. The comparison is used to set a diagnostic indicator, which is checked to determine if the engine should be directed to the next assembly area or returned to a repair area so that the correct sensor may be installed.

Claims

1. A test method for verifying correct production of engines having first and second fueling characteristics, wherein fueling of each of the engines is controlled by a respective electronic control module, wherein engines having the first fueling characteristic are designed to be equipped with a first type of exhaust gas oxygen sensor, and engines having the second fueling characteristic are designed to be equipped with a second type of exhaust gas oxygen sensor, and wherein each such exhaust gas oxygen sensor includes a heater element that is supplied with electrical current by the respective electronic control module during operation of a respective engine, the test method comprising the steps of:

specifying an electrical resistance of the heater elements of said first and second types of exhaust gas oxygen sensors such that the electrical resistance of heater elements for the first type of exhaust gas oxygen sensor fall in a first range, and the electrical resistance of the heater elements for the second type of exhaust gas oxygen sensor fall in a second range;

storing a calibration parameter in the electronic control module for each engine, where the parameter stored in engines having the first fueling characteristic corresponds to said first range of electrical resistance, and the parameter stored in engines having the second fueling characteristic corresponds to said second range of electrical resistance;

starting a produced engine equipped with an exhaust gas oxygen sensor;

detecting an electrical current supplied to the equipped exhaust gas oxygen sensor by the respective electronic control module;

comparing the detected electrical current to the calibration parameter stored in the respective electronic control module; and

indicating that the equipped exhaust gas oxygen sensor matches the produced engine if the detected electrical current matches the stored calibration parameter, and that the equipped exhaust gas oxygen sensor fails to match the produced engine if the detected electrical current does not match the stored calibration parameter.

2. The test method of claim 1, wherein the step of detecting the electrical current supplied to the equipped exhaust gas oxygen sensor comprises the steps of:

periodically sampling values of electrical current supplied to the equipped exhaust gas oxygen sensor during a predefined period beginning when the respective electronic control module starts supplying electrical current to the equipped exhaust gas oxygen sensor;

accumulating the periodically sampled values of electrical current; and

at an end of said predefined period, calculating an average current based on the accumulated sampled values.

3. The test method of claim 2, wherein the end of said predefined period occurs when a predetermined number of said electrical current values have been sampled.

4. The test method of claim 1, including the step of:

disabling the detecting, comparing and indicating steps if a temperature of the produced engine exceeds a reference temperature.

5. The test method of claim 1, including the steps of:

indicating completion of the test method after indicating that the equipped exhaust gas oxygen sensor matches or fails to match the respective engine; and

disabling the detecting, comparing and indicating steps after completion of the test method has been indicated.