Fluid State Detection Apparatus Short Failure Diagnosis
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing fluid state detection apparatuses face difficulties in detecting short failures in the Wheatstone bridge circuit, as the output remains within the normal range, making it challenging to distinguish between normal operation and short failure states.
Innovation Solution
A fluid state detection apparatus is designed with a Wheatstone bridge circuit, a bridge control section, and a computation section, including an operational amplifier and energization control section, which compares potential differences to determine if the bridge circuit is shorted to the power supply by using a failure judgment section to differentiate between short failure and normal resistance changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the Wheatstone bridge circuit is used for fluid state detection, then measurement precision is improved, but the ability to detect short failures deteriorates because the output remains within normal range
Solution Approach 1:
The patent divides the detection function into two independent parts: the Wheatstone bridge circuit for normal fluid state detection and the parallel resistor circuit for short failure detection. This segmentation allows each circuit to perform its specific function without interfering with the other, enabling both precise fluid state measurement and reliable short failure detection to coexist in the same system
Solution Approach 2:
The parallel resistor circuit acts as an intermediary detection mechanism that monitors the voltage at the bridge circuit's output node. By measuring the voltage between this node and ground through the parallel resistor, the system can indirectly detect short failures without disrupting the primary fluid state detection function of the Wheatstone bridge
2Reliability
If the resistance of resistor sections is properly set to detect open failures, then open failure detection is improved, but short failure detection remains difficult
Solution Approach 1:
The patent makes the parallel resistor circuit serve multiple functions: it enables short failure detection by providing a reference path to ground, and simultaneously works with the operational amplifier to maintain the detection of open failures through the existing bridge circuit configuration. This multi-functionality adds short failure detection capability without requiring a completely separate detection system
Solution Approach 2:
The parallel resistor circuit creates an equipotential reference path by connecting the bridge output node to ground through a known resistance. This establishes a predictable voltage relationship that remains valid under normal operation but changes distinctly when a short failure occurs, providing a reliable basis for failure detection without affecting open failure detection mechanisms
3Stability of the object's composition
If feedback control is performed to maintain operational amplifier output within normal range, then operational stability is improved, but short failure detection capability deteriorates
Solution Approach 1:
The patent adds another dimension to the detection system by introducing a parallel detection path through the parallel resistor circuit. While the feedback control maintains the operational amplifier output within the normal voltage range for stable operation, the parallel resistor provides an additional measurement dimension (voltage to ground) that reveals short failure conditions without requiring the main output to deviate from its stable range
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 apparatus effectively detects short failures in the energization control section, allowing for accurate differentiation between short failure states and normal fluid state detection operations, enhancing the reliability of hydrogen gas concentration measurements.
Implementation Method 1
measures the amount of heat transferred from the heat generation resistor to the fluid to be detected and calculates a change in the heat conduction of the fluid to be detected
Implementation Method 2
a Wheatstone bridge circuit which includes the heat generation resistor as one of four resistor sections
Implementation Method 3
measures the amount of heat transferred from the heat generation resistor to the fluid to be detected using a Wheatstone bridge circuit
Data Source
AI summary
A fluid state detection apparatus which can detect a short failure in which a constituent Wheatstone bridge circuit is shorted to a power supply. A combustible gas detection apparatus (1) judges that a short failure has occurred in a constant temperature control circuit (231) (S240) when a top potential V21 is equal to or greater than a first judgment value Vth1 and a difference D1 (=V11−V31) is equal to or greater than a second judgment value Vth2. As a result, apparatus (1) can distinguish “a state in which a bridge circuit (210) is shorted to a DC power supply (40) (where the constant temperature control circuit 231 is in a short failure state)” from “a state in which the resistance of the heat generation resistor (15) deceases due to a combustible gas (hydrogen)” based on the top potential V21 and the difference D1.