Thermal Sensor Fault Detection via Dual-Mode Operation
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Solution Overview
Problem
Existing thermal sensor devices for determining fluid parameters struggle to reliably detect sensor faults that can compromise accuracy, particularly in safety-relevant applications where subtle malfunctions may go unnoticed.
Innovation Solution
A thermal sensor device operates in two modes: a steady-state mode and a dynamic mode to independently determine fluid parameters, with processing circuitry comparing the results to derive a fault indicator value, enabling detection of sensor faults such as drifts or contaminations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thermal sensor device uses a single operational mode to determine fluid parameters, then the device complexity is reduced, but the reliability of fault detection deteriorates
Solution Approach 1:
The system dynamically switches between two operational modes (steady-state mode and dynamic mode) to perform measurements. By varying the operational state and comparing results from different modes, the system enhances fault detection capability without requiring additional hardware, thus resolving the contradiction between reliability and complexity.
Solution Approach 2:
The system changes measurement parameters by operating in different modes: steady-state mode measures temperature differences under constant conditions, while dynamic mode measures transient response to step changes. This parameter variation enables cross-validation of measurements for fault detection while maintaining a single sensor device structure.
2Reliability
If a thermal sensor device operates in multiple modes to detect faults, then the reliability of fault detection is improved, but the measurement time increases
Solution Approach 1:
The system performs periodic switching between steady-state measurements and dynamic mode measurements. By alternating between these modes at appropriate intervals, the system achieves continuous fault detection capability while maintaining efficient use of measurement time, preventing excessive time loss.
Solution Approach 2:
The system performs preliminary steady-state measurements to establish baseline temperature differences before executing dynamic mode measurements. This preliminary action allows for efficient transient response measurement and reduces total measurement time by preparing the system in advance.
3Measurement precision
If a thermal sensor device uses steady-state measurements to determine fluid parameters, then the measurement precision is improved, but the response time deteriorates
Solution Approach 1:
The system uses dynamic mode measurements with step changes in heater power to obtain rapid transient response data. This dynamic approach provides fast response time for detecting changes in fluid parameters, complementing the precision of steady-state measurements.
Solution Approach 2:
The system changes the measurement parameter from steady-state temperature difference to transient response time constant. By measuring the time constant during dynamic mode, the system achieves fast response while maintaining measurement precision through the relationship between transient response and fluid thermal properties.
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
This approach allows for reliable detection of sensor faults by comparing the fluid parameter values from different operational modes, enhancing the accuracy and reliability of fluid parameter determination and facilitating predictive maintenance.
Implementation Method 1
Heat transfer between the heater and the temperature sensors is influenced by heat transfer through the fluid
Implementation Method 2
determine a fluid parameter of a fluid in thermal contact with the thermal sensor device based on a heat transfer behavior of the fluid
Data Source
AI summary
A thermal sensor device is configured to determine a fluid parameter of a fluid based on the heat transfer behavior of the fluid. The sensor device comprises one or more heaters and means for determining a response of the sensor device to heater power being supplied to the heaters. For detecting sensor faults, the sensor device is operated in two different modes of operation. First and second values (cstatic, cdynamic) of the same fluid parameter are determined in the two modes. A fault indicator value (F) is derived by comparing the first and second values. The first mode of operation may be a steady-state mode, the first value (cstatic) being based on a steady-state response of the sensor device to heater power being supplied to the heaters, and the second mode of operation may be a dynamic mode, the second value (cstatic) being based on a transient response.