Gas Sensor Control Device Diagnostic Resistance Circuit
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Solution Overview
Problem
Conventional gas sensor systems using DA conversion circuits lack a method to detect supply errors in pump current due to the absence of fixed resistance in the supply path, making it difficult to diagnose whether the DA conversion circuit operates correctly.
Innovation Solution
A gas sensor control device with a DA conversion circuit, a reference electric potential generating circuit, a diagnostic resistance connected in parallel to the pump cell, and an output part that sends a signal to an external device when oxygen ion conductivity does not occur, allowing for the diagnosis of DA conversion circuit failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a DA conversion circuit is used to supply pump current, then circuit size is reduced and digital control is achieved, but the ability to detect supply errors is lost due to absence of fixed resistance
Solution Approach 1:
The patent introduces a diagnostic resistance as an intermediary component connected in parallel to the pump cell. This diagnostic resistance serves as a mediator that enables error detection without interfering with the primary function of the pump cell. When the pump cell is inactive, the diagnostic resistance provides a known resistance value that allows the system to verify the DA conversion circuit's output current, thereby restoring diagnosis capability while maintaining the benefits of digital control.
2Measurement precision
If direct measurement through fixed resistance is used, then supply error detection is enabled, but the circuit design becomes incompatible with DA conversion circuits
Solution Approach 1:
The patent implements a dynamic circuit configuration where the diagnostic resistance is connected in parallel to the pump cell and can be selectively utilized during different operational phases. During pump cell operation, the pump cell dominates the circuit behavior. During diagnostic phases when the pump cell is inactive, the diagnostic resistance becomes the active measurement path. This dynamic switching capability enables both precise measurement and compatibility with DA conversion circuits.
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 the diagnosis of DA conversion circuit failures by outputting a signal related to the voltage applied to the diagnostic resistance, ensuring correct current supply magnitude, thereby improving system reliability.
Implementation Method 1
a pump cell having a first pump electrode and a second pump electrode that are separately arranged on the solid electrolyte... in a situation in which oxygen ion conductivity does not occur in the pump cell
Implementation Method 2
a diagnostic resistance connected to the pump cell parallel to the pump cell; and an output part configured to output a signal relating to voltage applied to the diagnostic resistance
Data Source
AI summary
A gas sensor control device having a DA conversion circuit configured to supply a pump current having a magnitude corresponding to an inputted digital signal to the pump cell, a reference electric potential generating circuit configured to keep an electric potential of the first pump electrode at a reference electric potential, a diagnostic resistance connected to the pump cell parallel to the pump cell, and an output part configured to output a signal relating to voltage applied to the diagnostic resistance when inputting an arbitrary digital signal to the DA conversion circuit in a situation in which oxygen ion conductivity does not occur in the pump cell to an external device.