Air-Fuel-Ratio Sensor Controller Short Circuit Detection
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Solution Overview
Problem
Conventional air-fuel-ratio sensors face challenges in accurately detecting short circuits between the pump cell and detection cell, which hampers reliable air-fuel ratio detection.
Innovation Solution
A controller and abnormality detecting method that applies a sweeping current or voltage to the detection cell, monitoring fluctuations in voltage and current to determine if a short circuit has occurred by comparing changes in IP and VS terminals, thereby enhancing detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional abnormality detection methods are used, then the detection process is simple, but the detection accuracy of short circuits between pump cell and detection cell is insufficient
Solution Approach 1:
The patent segments the detection process into distinct phases: normal operation monitoring, sweeping process execution, and abnormality detection. By dividing the detection into these separate stages with clear transitions, the system achieves high detection accuracy without creating a permanently complex device structure.
Solution Approach 2:
The patent implements periodic sweeping processes where a test voltage is applied at specific intervals during normal operation. This periodic action allows the system to maintain simple overall architecture while achieving accurate short circuit detection through temporary, controlled modifications to the operating state.
2Measurement precision
If a sweeping process is applied to detect short circuits, then detection accuracy improves, but processing time increases
Solution Approach 1:
The patent implements a time-limited sweeping process that rushes through the detection phase quickly. The test voltage is applied for a predetermined short duration just long enough to detect abnormalities, then immediately reverted to normal operation voltage, minimizing time loss while maintaining detection accuracy.
Solution Approach 2:
The sweeping process is performed periodically rather than continuously, allowing the system to alternate between normal operation and brief detection phases. This periodic approach ensures accurate detection while limiting the time spent in the detection state to predetermined intervals.
3Reliability
If continuous monitoring of voltage and current is performed, then detection reliability improves, but energy consumption increases
Solution Approach 1:
The patent performs monitoring continuously during the sweeping process but only initiates sweeping periodically during normal operation. This creates a hierarchy of periodic actions where brief intensive monitoring periods are embedded within longer normal operation periods, maintaining reliability while controlling average energy consumption.
Solution Approach 2:
The patent ensures that during the sweeping process, monitoring of voltage and current changes continues without interruption to detect short circuits reliably. However, the sweeping itself is activated only when abnormality detection is prioritized, maintaining continuous useful action during critical detection phases while allowing energy-saving modes during stable operation.
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 high-accuracy detection of short circuits between the pump and detection cells, improving the reliability of air-fuel ratio sensing and reducing processing loads.
Implementation Method 1
a gas sensor element (1) including a pump cell (4) that pumps and pumps out oxygen into and from a gas detecting chamber (90) and a detection cell (5) that detects an oxygen concentration of the gas detecting chamber (90)
Implementation Method 2
a pump cell (4) that pumps and pumps out oxygen into and from a gas detecting chamber (90)
Data Source
Figure 1
Figure 2
Figure 3~5
AI summary
A controller (3) of an air-fuel-ratio sensor (100) according to an embodiment includes a current supplying unit (13), a sweep processing unit (16), and an abnormality detecting unit (20). The current supplying unit (13) supplies a current (Ip) to the pump cell (4) through a first terminal (Tip) connected with the pump cell (4) so as to control the pump cell (4). The sweep processing unit (16) executes a sweeping process in which a predetermined voltage (Vm) or a predetermined current (Im) is applied to the detection cell (5) through a second terminal (Tvs) connected with the detection cell (5) so as to change a voltage (Vs) and a current (Is) of the detection cell (5). The abnormality detecting unit (20) detects a shortcircuited state between the first terminal (Tip) and the second terminal (Tvs) on the basis of a fluctuation in a voltage (Vp) or a current (Ip), generated by the sweeping process, of the first terminal (Tip).