Configurable interface circuit for exhaust gas oxygen sensors

• US 6,831,471 B2
• Filed: 11/14/2002
• Issued: 12/14/2004
• Est. Priority Date: 11/14/2002
• Status: Expired due to Term

• Current Assignee: Delphi Technologies Ip Limited (BorgWarner Incorporated)
• Original Assignee: Delphi Technologies, Inc. (BorgWarner Incorporated)
• Inventors: Kinley, James A., Manlove, Gregory J., Gertiser, Kevin M., Kamel, Ashraf K.
• Primary Examiner(s): Deb, Anjan
• Assistant Examiner(s): Teresinski, John
• Application Number:
  US10/294,380
• Publication Number:
  US 20040095153A1
• Time in Patent Office: 761 Days
• Field of Search: 324/693, 324/609, 324/691, 204/425
• US Class Current: 324/693
• CPC Class Codes: F02D 2041/2075 Type of transistors or particular use thereof
• CPC Class Codes: F02D 2041/2089 detecting open circuits
• CPC Class Codes: F02D 2041/2093 detecting short circuits
• CPC Class Codes: F02D 2200/503 Battery correction, i.e. corrections as a function of the state of the battery, its output or its type
• CPC Class Codes: F02D 41/1441 Plural sensors
• CPC Class Codes: F02D 41/1479 Using a comparator with variable reference
• CPC Class Codes: F02D 41/1495 Detection of abnormalities in the air/fuel ratio feedback system
• CPC Class Codes: F02D 41/1496 Measurement of the conductivity of a sensor F02D41/1455 takes precedence
• CPC Class Codes: F02D 41/2474 Characteristics of sensors

Abstract

An oxygen sensor interface circuit is configurable on the fly by an electronic controller such as an engine controller to support oxygen sensors having unique interface requirements, to reliably identify various oxygen sensor faults, and to enable rapid detection of a warmed up sensor. The interface circuit is configurable in a first respect to enable operation with any of a number of different sensors, and in a second respect to enable more reliable fault detection, including measurement of leakage to ground or battery.

Claims

1. An interface circuit coupled to an electronic control unit and an exhaust gas oxygen sensor, comprising:

an amplifier having an input coupled to the oxygen sensor and an output coupled to the electronic control unit;

a plurality of different bias circuits for diagnosing the oxygen sensor, said bias circuits being designed in accordance with diagnostic requirements of different types of oxygen sensors; and

dynamically configurable means controlled by the electronic control unit for connecting a selected one of said different bias circuits to the amplifier input so that the selected bias circuit is designed in accordance with diagnostic requirements of the oxygen sensor that is coupled to said interface circuit, wherein at least one of said bias circuits receives a reference voltage from said electronic control unit that is adjustable for diagnostic purposes when such bias circuit is selected by said dynamically configurable means, and said electronic control unit includes diagnostic means for setting said reference voltage to a diagnostic value that produces a known output of said amplifier when there is no electrical leakage path between said sensor and another electrical potential, and for diagnosing the existence of an electrical leakage path when the output of said amplifier is different than said known value.

2. The interface circuit of claim 1, wherein said electronic control unit is connected to a storage battery, and said diagnostic means diagnoses a leakage path between said sensor and said storage battery when the output of said amplifier is higher than said known value.

3. The interface circuit of claim 2, wherein said diagnostic means determines an effective resistance of the diagnosed leakage path as a function of said diagnostic value, a measured voltage of said storage battery, and the output of said amplifier.

4. The interface circuit of claim 1, wherein said electronic control unit is connected to a ground potential, and said diagnostic means diagnoses a leakage path between said sensor and said ground potential when the output of said amplifier is lower than said known value.

5. The interface circuit of claim 4, wherein said diagnostic means determines an effective resistance of the diagnosed leakage path as a function of said diagnostic value and the output of said amplifier.