Two-Step Lambda Oxygen Sensor Curve Correction
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Solution Overview
Problem
Two-step lambda oxygen sensors in internal combustion engines face challenges in maintaining a consistent voltage-lambda characteristic curve due to manufacturing tolerances and aging effects, limiting their ability for continuous closed-loop control across the entire operational life, especially in lean and rich air-fuel mixture operations.
Innovation Solution
A method and device that adjust the operating parameters of the two-step lambda oxygen sensor to correct deviations in the voltage-lambda characteristic curve relative to a reference curve by changing the air-fuel mixture composition, allowing for accurate continuous control without relying on trailing throttle fuel cutoff phases, and considering additive or multiplicative effects across different lambda ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a two-step lambda oxygen sensor is used for cost reduction, then manufacturing cost is reduced, but measurement precision and reliability deteriorate due to manufacturing tolerances and aging effects
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the operating parameters of the two-step lambda oxygen sensor, specifically the heating power and air-fuel mixture composition, to compensate for manufacturing tolerances and aging effects. This allows the sensor to maintain accurate voltage-lambda characteristic curves throughout its service life without requiring expensive precision manufacturing.
2Device complexity
If a two-step lambda oxygen sensor is used instead of a broadband sensor, then device complexity and cost are reduced, but adaptability deteriorates as continuous closed-loop control is not possible across the entire lambda range
Solution Approach 1:
The patent applies dynamics by making the operating parameters of the two-step lambda oxygen sensor adjustable and adaptable in real-time. By dynamically changing the heating power and air-fuel mixture composition based on feedback from the sensor, the system achieves continuous closed-loop control capability across the entire lambda range, transforming a static sensor into a dynamically controllable system.
Solution Approach 2:
The patent changes the operating parameters (heating power, air-fuel mixture) of the two-step sensor to enable it to function effectively across different lambda ranges, achieving adaptability without requiring a more complex broadband sensor architecture.
3Measurement precision
If traditional calibration methods using trailing throttle fuel cutoff are used, then measurement precision is improved at that specific operating point, but productivity and reliability deteriorate due to limited availability of such phases and inability to compensate across the entire lambda range
Solution Approach 1:
The patent implements continuous calibration and compensation across the entire lambda range by operating the sensor under controlled air-fuel mixture conditions throughout different operating modes. This eliminates the discontinuity of traditional methods that rely on specific trailing throttle phases, ensuring continuous useful action for maintaining measurement precision.
Solution Approach 2:
The patent changes the operating parameters systematically across different lambda ranges to enable calibration and compensation at multiple operating points, not just at trailing throttle fuel cutoff. This allows the system to maintain measurement precision across the entire operational spectrum.
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
Enables precise and continuous closed-loop lambda control upstream of the catalytic converter, effectively compensating for tolerance and aging-induced deviations, and allowing the use of low-cost two-step sensors for accurate pollutant emission management.
Implementation Method 1
In the case of a two-step lambda oxygen sensor, also referred to as a discrete-level sensor or Nernst sensor, the voltage-lambda characteristic curve exhibits a step change in the characteristic curve profile at lambda=1
Data Source
AI summary
A method and device for correcting a voltage-lambda characteristic curve of a two-step lambda oxygen sensor in an exhaust tract relative to a reference-voltage lambda characteristic curve of the oxygen sensor; a deviation in the characteristic curve relative to the reference characteristic curve at lambda=1 being corrected; based on a value pair on the reference-voltage lambda characteristic curve, the composition of the air-fuel mixture supplied to the engine being changed toward lambda=1; the actual value of lambda being inferred from the change in the composition of the air-fuel mixture. The adaptation of the operating parameters of the oxygen sensor is intended to eliminate the cause of a deviation. Efforts are not merely directed to adapting the deviation to the reference characteristic curve by shifting the voltage-lambda characteristic curve. Effects, which may lead to tolerance- or aging-induced falsifications of the voltage-lambda characteristic curve, can be fully compensated.