Oxygen Sensor Pump Line Charge Restoration
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Solution Overview
Problem
Diagnostic routines in oxygen sensors disrupt the closed loop control and cause charge imbalances in the cells, leading to errors in air/fuel ratio readings due to the opening of the pump control loop and open circuit diagnostic mechanisms, which result in prolonged recovery times.
Innovation Solution
A method where, subsequent to a diagnostic process, a pull-up current is injected onto the pump line for a predetermined period to restore the charge lost in the pump and reference cells, using additional circuitry to provide a current source and maintain the cells at a nominal voltage, thereby minimizing disruptions and errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If diagnostic routines are implemented to test sensor connections, then reliability of sensor operation is improved, but charge balance in the cells is disrupted causing measurement precision to deteriorate
Solution Approach 1:
The patent applies preliminary action by restoring charge balance immediately after diagnostic routines complete. The microcontroller detects when diagnostics end and automatically injects compensating current to replenish charge removed during testing, preventing measurement errors before they occur. This proactive approach ensures measurement precision is maintained without sacrificing diagnostic reliability.
2Ease of operation
If the pump control loop is opened during diagnostic to test connections, then ease of operation is improved, but charge values in cells are disrupted causing loss of time
Solution Approach 1:
The patent converts the harmful effect of charge disruption during diagnostics into a beneficial recovery process. By measuring the pump current required to restore charge balance after diagnostics, the system quantifies the charge removed and uses this information to automatically replenish it. This transforms the previously harmful charge loss into a controlled, measurable, and recoverable process that minimizes recovery time.
3Reliability
If the return line is pulled high during open circuit diagnostic, then reliability is improved, but charge is pulled out of cells causing measurement precision to deteriorate
Solution Approach 1:
The patent implements feedback by continuously monitoring pump current and using this information to control charge restoration. After diagnostics complete, the microcontroller measures the pump current required to restore charge balance and uses this feedback to determine when charge balance is restored. This closed-loop feedback ensures that pump current readings accurately reflect actual gas conditions, maintaining measurement precision while preserving the reliability benefits of open circuit testing.
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
This approach quickly restores the charge balance in the sensor cells, reducing errors and recovery time, ensuring accurate air/fuel ratio readings post-diagnostic testing.
Implementation Method 1
a pump cell, adapted to pump oxygen into or out of the measurement chamber by means of an electric current
Implementation Method 2
The pump line and return lines are connected to ground via respective capacitances
Data Source
AI summary
A method of operating an oxygen sensor system is provided where the system includes an oxygen sensor, the oxygen sensor including a pump cell, and wherein the oxygen sensor is connected to associated circuitry such that the associated circuitry controls operation of the pump cell. The pump cell includes a pump line connected to a pump electrode of the pump cell and a return line connected to a return electrode of the pump cell. The method includes, subsequent to a diagnostic process, raising the potential of the pump line for a predetermined period of time by injecting current onto the pump line.