Lambda Sensor Calibration for Off-Road Engine Control
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Solution Overview
Problem
Existing methods for calibrating lambda sensors in internal combustion engines are limited to applications with coasting phases, such as vehicles, and cannot be used in off-road applications where coasting phases do not occur, leading to imprecise lambda control and potential pollutant emission issues.
Innovation Solution
A method for automatic lambda control that includes determining a calibration factor for the lambda sensor during engine coastdown, either by deactivating injection or temporarily increasing engine speed to prolong the coastdown phase, allowing for precise calibration without additional devices, and setting a time window to determine a maximum lambda measuring signal within a tolerance range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the lambda sensor is calibrated using the existing method requiring coasting phases, then the calibration can be performed, but the method cannot be applied in off-road applications where coasting phases do not occur
Solution Approach 1:
The invention changes the operating parameters by temporarily increasing engine speed from idle to a calibrating speed before deactivating injection. This creates a controlled coastdown phase with sufficient air volume flow for accurate lambda sensor calibration, enabling the method to work in off-road applications without natural coasting phases
Solution Approach 2:
The invention performs preliminary action by temporarily increasing engine speed to a calibrating speed before deactivating injection. This prepares the system with sufficient air volume flow in advance, ensuring accurate calibration conditions are met even when natural coasting is not available
2Measurement precision
If the engine speed is temporarily increased to prolong the coastdown phase, then more air volume flow is available for calibration, but the calibration time is extended
Solution Approach 1:
The invention applies partial action by temporarily increasing engine speed to a specific calibrating speed (not full operating speed) for the duration needed to accumulate sufficient air volume flow. This provides enough calibration data without excessively extending the total calibration time
3Measurement precision
If the maximum lambda measuring signal is determined within a time window, then the calibration factor can be calculated, but the method becomes more complex
Solution Approach 1:
The invention segments the calibration process into distinct phases: temporarily increasing engine speed, deactivating injection, determining the maximum lambda measuring signal within a time window, and calculating the calibration factor. This segmentation makes the control algorithm more manageable and implementable while maintaining calibration accuracy
Data Source
AI summary
A method for automatic lambda control of an internal combustion engine, in which, upon detection of a predetermined operating state of the internal combustion engine, a calibration factor (KAL) is determined and in which, during the operation of the internal combustion engine, a lambda measuring signal (iP) is corrected by the calibration factor (KAL) and is set as the actual lambda value (Lam(IST)) for the automatic lambda control of the internal combustion engine. The predetermined operating state is recognized when an engine coastdown is initiated.