Single Cell YSZ Oxygen Sensor for Engine Control
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Solution Overview
Problem
Dual-cell gas sensors used in automotive applications are costly, bulky, fragile, and have slow response times, making them unsuitable for efficient oxygen sensing in engine control systems, and are limited by switch-on and switch-off transients affecting measurement accuracy.
Innovation Solution
A single cell Yttrium stabilized ZrO2 (YSZ) oxygen sensor apparatus with a substrate, electrodes, and heater elements, where a constant current is applied to evacuate oxygen from a cavity, allowing partial pressure measurement by halting the current and measuring voltage decay across the YSZ layer when a preset voltage is reached, using a fixed resistance to induce ionic leakage and determine oxygen partial pressure differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If dual-cell gas sensors are used to measure oxygen concentration, then measurement capability is achieved, but device complexity, cost, and size increase
Solution Approach 1:
The patent extracts and eliminates the second cell from the dual-cell sensor configuration, using only a single electrolyte cell for measurement. This simplifies the device structure while maintaining measurement capability through a different operational approach that uses voltage decay timing instead of dual-cell comparison.
Solution Approach 2:
The measurement process is segmented into distinct phases: a pumping phase to remove oxygen from the measurement space, followed by a measurement phase where voltage decay is monitored. This temporal segmentation allows accurate measurement with a single cell, avoiding the need for complex dual-cell simultaneous operation.
2Measurement precision
If dual-cell gas sensors are used to measure oxygen concentration, then measurement capability is achieved, but response time becomes slow
Solution Approach 1:
The sensor employs periodic pumping cycles to remove oxygen from the measurement space, followed by rapid voltage decay measurement. This periodic action enables fast response times by continuously refreshing the measurement space and quickly detecting changes in oxygen concentration through voltage decay timing.
3Measurement precision
If dual-cell gas sensors are used to measure oxygen concentration, then measurement capability is achieved, but device fragility increases
Solution Approach 1:
The patent removes the second cell and its associated glass/ceramic sealing components from the sensor design. This extraction of unnecessary components directly improves device robustness and reliability, making the sensor more suitable for harsh automotive environments while maintaining measurement accuracy through the simplified single-cell architecture.
4Productivity
If measurement time intervals are made small to improve response speed, then productivity increases, but measurement accuracy deteriorates due to switch-on and switch-off transients
Solution Approach 1:
The sensor performs a preliminary pumping phase to completely remove oxygen from the measurement space before initiating the voltage decay measurement. This preliminary action eliminates switch-on transients by ensuring the measurement starts from a known zero-oxygen state, allowing accurate measurements even with short time intervals.
Solution Approach 2:
The patent converts the voltage decay phenomenon, which could be seen as a harmful transient effect, into a useful measurement signal. By monitoring the timing and characteristics of the voltage decay after pumping, the system accurately determines oxygen concentration while maintaining fast response times.
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
The single cell YSZ sensor provides improved accuracy and efficiency in measuring oxygen partial pressure with reduced transient influences, offering a cost-effective, compact, and robust solution for engine control applications.
Implementation Method 1
a separation wall which exhibits ionic conduction
Implementation Method 2
the equivalent circuit diagram of the separation wall comprises besides resistances also capacitances, as a result of which RC time constants and stored capacitor charges are obtained
Implementation Method 3
utilizing a fixed resistance across the electrical terminals when a voltage across the yttrium-based stabilized layer attains a particular preset value. The voltage across the yttrium-based stabilized layer and ionic leakage of the oxygen through the yttrium-based stabilized layer then decreases
Data Source
AI summary
A single cell oxygen sensor apparatus and method are disclosed. An yttrium-based stabilized layer having electrical terminals connected to the yttrium-based stabilized layer can be provided on a substrate, wherein the yttrium-based stabilized layer is excitable by a constant current applied to the electrical terminals. A plurality of electrodes are located on a side of the yttrium-based stabilized layer and a plurality of heater elements located on said substrate opposite said yttrium-based stabilized layer. The heater elements can maintain the yttrium-based stabilized layer at a particular temperature. A cavity is formed and located between the yttrium-based stabilized layer and the heater elements. The partial pressure of oxygen can be measured by comparing the partial pressure of oxygen within the cavity with respect to the partial pressure of oxygen in the atmosphere external to the single cell oxygen sensor apparatus.