Oxygen Sensor Disconnection Diagnosis via Voltage Divider
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Solution Overview
Problem
Existing methods fail to accurately diagnose disconnection of oxygen sensors in vehicles, leading to inefficient air-fuel ratio control and increased harmful gas emissions, as they cannot precisely determine whether the oxygen sensor is functioning correctly.
Innovation Solution
A method and apparatus that measure the voltage and internal resistance of the oxygen sensor, using a voltage divider and controller to determine if the ground wire is disconnected by comparing values before and after blocking a pumping current, while ensuring the sensor is activated and the engine is normally driven.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing diagnostic methods are used for oxygen sensors, then the system is simple and easy to operate, but the measurement precision and reliability of disconnection diagnosis are insufficient
Solution Approach 1:
The diagnostic method segments the oxygen sensor testing into distinct phases: initial voltage measurement phase, pumping current blocking phase, and comparison phase. This allows systematic diagnosis of disconnection by measuring voltage at different operational states and comparing results against reference ranges, thereby improving diagnostic precision without requiring a completely complex new system architecture.
Solution Approach 2:
The system performs preliminary checks by measuring the voltage supplied to the oxygen sensor and the reference cell voltage before conducting the main disconnection diagnosis. These preliminary measurements establish baseline values that are stored as reference data, enabling more accurate subsequent diagnosis while preparing the system in advance for the actual detection task.
2Reliability
If voltage and internal resistance measurements are performed to diagnose disconnection, then the reliability of diagnosis is improved, but the use of energy and measurement time increase
Solution Approach 1:
The diagnostic system employs periodic action by blocking the pumping current in a controlled, time-limited manner and measuring voltages at specific intervals (initial voltage, voltage after blocking). This periodic measurement approach ensures reliable disconnection diagnosis while controlling the total diagnosis time through predefined measurement sequences and reference range comparisons.
3Measurement precision
If multiple voltage measurements and comparisons are conducted, then the accuracy of determining ground wire disconnection is improved, but the device complexity increases
Solution Approach 1:
The system implements feedback by comparing measured voltages (initial voltage, reference cell voltage, voltage after pumping current blocking) against pre-stored reference ranges. This feedback mechanism provides clear pass/fail criteria for disconnection diagnosis, improving detection accuracy while maintaining relatively simple system architecture through straightforward comparison logic rather than complex analysis algorithms.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Accurately diagnoses disconnection of the oxygen sensor, minimizing diagnosis errors and maintaining optimal sensor operation, thereby ensuring precise air-fuel ratio control and reducing harmful emissions.
Implementation Method 1
measuring, by a controller, a voltage supplied to an oxygen sensor through a voltage divider
Implementation Method 2
an oxygen sensor including a reference cell, a pump cell, and a measurement cell
Data Source
AI summary
A method for diagnosing disconnection of an oxygen sensor includes measuring, by a controller, a voltage supplied to an oxygen sensor through a voltage divider; measuring a voltage of a reference cell of the oxygen sensor; determining whether the voltage supplied to the oxygen sensor and the voltage of the reference cell fall within a reference range from preset reference values, respectively; and determining that a ground wire of the oxygen sensor is disconnected, when the voltage of the oxygen sensor or the voltage of the reference cell deviates from the reference range.