Oxygen Sensor Miswiring Compensation in V8 Engines
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Solution Overview
Problem
The uneven firing intervals in cross-plane crank V8 engines cause variations in residency times of exhaust pulses at oxygen sensors, leading to air-fuel ratio imbalance diagnostics issues when a sole oxygen sensor is used for each bank of cylinders, and miswiring of oxygen sensors can result in feedback control instability and emissions issues.
Innovation Solution
The method involves monitoring exhaust gases of two groups of cylinders within a cylinder bank using two oxygen sensors and switching the cylinders associated with these sensors in response to an indication of miswiring, allowing the engine controller to make internal adjustments to compensate for the miswiring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a sole oxygen sensor is used for each bank of cylinders, then device complexity is reduced, but air-fuel ratio imbalance diagnostic capability deteriorates
Solution Approach 1:
The patent divides the cylinder bank into two groups (first group and second group) and assigns separate oxygen sensors to each group. This segmentation allows independent monitoring of air-fuel ratios for different cylinder groups, enabling detection of imbalances that would be impossible with a single sensor monitoring all cylinders collectively.
2Measurement precision
If oxygen sensors are added to improve air-fuel ratio diagnostic capability, then measurement precision improves, but device complexity increases
Solution Approach 1:
The patent uses two oxygen sensors for four cylinders (one sensor per two cylinders), which is a partial solution that provides sufficient diagnostic capability without the excessive complexity of installing one sensor per cylinder. This partial action achieves the necessary measurement precision while maintaining reasonable device complexity.
3Ease of manufacture
If miswiring of oxygen sensors occurs, then ease of installation is improved, but feedback control stability deteriorates
Solution Approach 1:
The patent implements a diagnostic routine that continuously monitors oxygen sensor outputs and compares them against expected values. When miswiring is detected through feedback analysis of sensor signals, the system identifies the error and switches cylinder group assignments to correct the control instability, thereby maintaining reliability despite the ease of installation that allowed miswiring to occur.
4Ease of manufacture
If oxygen sensors are miswired to simplify wiring, then ease of installation improves, but emissions compliance deteriorates
Solution Approach 1:
The diagnostic routine monitors oxygen sensor outputs and fuel control parameters to detect miswiring conditions. When miswiring is detected, the system switches cylinder group assignments to correct the error, thereby preventing emissions from exceeding threshold levels despite the simplified wiring that initially caused the miswiring.
5Object-affected harmful factors
If cylinder switching is implemented to correct miswiring, then emissions compliance improves, but device complexity increases
Solution Approach 1:
The control system automatically detects miswiring conditions through monitoring of oxygen sensor outputs and autonomously switches cylinder group assignments to correct the error. This self-service capability resolves emissions compliance issues without requiring external intervention or complex additional hardware, thereby limiting the increase in device complexity to only the necessary software control logic.
Data Source
AI summary
Systems and methods for detecting and compensating miswiring of oxygen sensors of a cylinder bank of an engine are disclosed. In one example, fuel control parameters are monitored to determine whether or not the fuel control parameters diverge to fuel control thresholds. If so, a controller may switch which cylinder's equivalence ratios are adjusted in response to output of a particular oxygen sensor.