Oxygen Sensor Heater Voltage Integration for Cold Start Control
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Solution Overview
Problem
During cold starting of an internal combustion engine, the oxygen sensor takes tens of seconds to reach a threshold temperature, leading to inaccurate air-fuel ratio feedback and increased hydrocarbon emissions due to operating in open-loop control, which can result in engine misfire and oxygen sensor degradation.
Innovation Solution
A method involving a controller that supplies and adjusts voltage to the oxygen sensor heater based on estimated resistance to accelerate the sensor's temperature reach, allowing earlier transition to closed-loop air-fuel ratio control, reducing emissions and degradation risk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the engine operates in open-loop control mode during cold start, then the engine can run without stalling or misfiring, but hydrocarbon emissions significantly increase
Solution Approach 1:
The system performs preliminary heating of the oxygen sensor using integrated voltage from the heater during cold start, preparing the sensor to provide accurate feedback earlier. This preliminary action allows the engine to transition to closed-loop control sooner, reducing emissions while maintaining starting robustness
Solution Approach 2:
The system uses feedback from the oxygen sensor output to adjust engine air-fuel ratio. By integrating the heater voltage to estimate sensor temperature and readiness, the system determines when sufficient feedback is available to safely transition from open-loop to closed-loop control, thereby reducing emissions without compromising engine reliability
2Loss of time
If higher electrical power is supplied to the oxygen sensor heater, then the sensor reaches threshold temperature faster enabling closed-loop control, but oxygen sensor degradation may increase
Solution Approach 1:
The system dynamically adjusts the heater voltage based on integrated power delivery and estimated sensor temperature. Rather than applying fixed high power, the system modulates voltage to achieve threshold temperature as efficiently as possible, balancing rapid warm-up with prevention of excessive power that could degrade the sensor
Solution Approach 2:
The system uses feedback from integrating the heater voltage to monitor the energy delivered to the sensor. This integrated voltage measurement provides real-time information about sensor heating progress, allowing the control system to adjust power delivery to achieve threshold temperature quickly while preventing excessive power application that would cause degradation
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 improves engine starting robustness, reduces hydrocarbon emissions, and minimizes oxygen sensor degradation while enabling earlier closed-loop control at no significant additional cost to existing engine control systems.
Implementation Method 1
supplying a voltage to an oxygen sensor heater during a cold engine start via a controller; integrating the voltage
Data Source
AI summary
Systems and methods for operating an internal combustion engine that includes an oxygen sensor are described. In one example, a voltage that is applied to a heating element of an oxygen sensor is integrated to determine a resistance of the heating element. The resistance of the heating element is the basis for adjusting voltage applied to the heating element during subsequent engine starts.