Oxygen Sensor Heater Power Management for Cold Start
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Solution Overview
Problem
Existing systems for heating exhaust gas oxygen sensors in vehicles often face delays due to insufficient battery power during cold starts, especially with degraded or low-state-of-charge batteries, leading to prolonged open-loop AFR control and increased emissions.
Innovation Solution
Monitoring the power delivered to the oxygen sensor heater during cold starts and adjusting the battery charging strategy based on voltage drops to ensure sufficient power is available for expedited heating, with the alternator providing supplementary power if needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the battery is used to power the oxygen sensor heater during cold start, then the oxygen sensor can be heated, but the battery power may be insufficient to heat the sensor quickly enough
Solution Approach 1:
The system performs preliminary charging of the battery during vehicle operation before the cold start occurs. The control unit monitors battery state of charge and adjusts the charging rate to ensure sufficient power is available when the oxygen sensor heater is needed during cold start, thereby enabling fast heating without compromising battery power availability.
2Power
If the battery state of charge is increased prior to engine start, then more power is available for heating, but the charging time required increases
Solution Approach 1:
The system dynamically adjusts the battery charging rate based on real-time monitoring of battery state of charge, vehicle operating conditions, and predicted cold start requirements. The control unit varies the charging current to optimize the balance between achieving sufficient power levels and minimizing charging time, rather than using a fixed charging rate.
Solution Approach 2:
The control unit continuously monitors battery voltage, current, and state of charge, and uses this feedback to adjust the charging strategy. When the battery approaches sufficient charge levels, the charging rate is reduced or stopped, preventing unnecessary charging time extension while ensuring adequate power is available for the oxygen sensor heater.
3Reliability
If the oxygen sensor heating is delayed, then battery power constraints are respected, but the closed-loop AFR control is delayed and emissions increase
Solution Approach 1:
The system prepares the battery for oxygen sensor heating by adjusting the charging strategy in advance during vehicle operation. The control unit monitors battery state of charge and ensures sufficient power is accumulated before cold start, so that when the oxygen sensor heater is activated, full power is immediately available for rapid heating and timely closed-loop AFR control, minimizing emissions.
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 enables faster oxygen sensor heating, allowing for earlier initiation of closed-loop AFR control, thereby improving emissions quality and reducing cold-start emissions.
Implementation Method 1
an oxygen sensor may be heated by a heating element to bring the sensor temperature within a desired range
Implementation Method 2
An alternator may be engaged to provide power to the heater and compensate for lower battery power supply
Data Source
AI summary
Methods and systems are provided for a battery supplying power to an exhaust oxygen sensor heater. In one example, a method may include estimating a power delivered to the heater during heating of the sensor and in response to a power delivered from a battery being lower than a threshold, adjusting a battery charging strategy prior to an immediately subsequent engine start.