Dynamic Threshold Valve Failure Detection in Engine Cooling Systems
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Solution Overview
Problem
Existing engine cooling systems face challenges in accurately detecting stuck-closed failures in valves due to varying temperature differences between coolant temperatures, leading to potential false positives or false negatives.
Innovation Solution
The cooling system incorporates a first and second flow passage, a third flow passage, a first valve, a second valve, a first temperature sensor, a second temperature sensor, and a determination unit that adjusts thresholds based on the operational state of the valves to accurately determine stuck-closed failures by varying the temperature difference threshold when the first valve is open or closed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a uniform threshold is used for temperature difference detection, then the detection method is simple, but the accuracy of detecting stuck-closed failure decreases due to varying temperature differences under different thermostat states
Solution Approach 1:
The threshold value is made dynamic rather than static. The determination unit changes the threshold value based on the thermostat state (open or closed), allowing the detection system to adapt to varying temperature differences under different operating conditions. This resolves the contradiction by enabling accurate detection without requiring an overly complex system.
Solution Approach 2:
The system changes the threshold parameter according to the thermostat state. When the thermostat is open, a first threshold is used; when closed, a second threshold is used. This parameter adjustment allows the system to maintain high detection accuracy across different operating conditions while keeping the overall system relatively simple.
2Reliability
If the threshold is set high to avoid false positives, then false alarms decrease, but stuck-closed failures may not be detected (false negatives)
Solution Approach 1:
The system uses different threshold values corresponding to different thermostat states. A first threshold is applied when the thermostat is open, and a second threshold is applied when closed. This allows the system to optimize the balance between false positives and false negatives for each operating condition, improving overall reliability without sacrificing detection sensitivity.
Solution Approach 2:
The determination unit continuously monitors the thermostat state and adjusts the threshold accordingly. This feedback mechanism ensures that the appropriate threshold is always active, preventing both false alarms and missed detections by adapting the detection criteria to current system conditions.
3Measurement precision
If the threshold is set low to detect all temperature differences, then detection sensitivity increases, but false positives increase due to normal temperature variations
Solution Approach 1:
The system dynamically adjusts the threshold parameter based on thermostat state. By using a first threshold when the thermostat is open and a second threshold when closed, the system maintains high sensitivity for detecting actual failures while filtering out false positives that would occur with a uniformly low threshold.
Solution Approach 2:
Different threshold values are applied to different operating conditions (local quality). The determination unit selects the appropriate threshold based on the current thermostat state, allowing the system to be highly sensitive when needed while being selective about false alarms in other conditions.
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 enhances the reliability of detecting stuck-closed failures in the second valve while minimizing false alarms, ensuring accurate determination of valve states and improving engine cooling efficiency.
Implementation Method 1
The first temperature sensor is in the first flow passage between the engine and the radiator. The second temperature sensor is installed in the second flow passage downstream of a connection portion of the second flow passage with the third flow passage.
Implementation Method 2
The first flow passage is configured to circulate a cooling medium through the engine and a radiator in this order
Implementation Method 3
The first flow passage is configured to circulate a cooling medium through the engine and a radiator in this order
Data Source
AI summary
A cooling system circulates a cooling medium between an engine and a radiator. The cooling system includes a determination unit. The determination unit sets a relatively small predetermined value for a threshold when a thermostat is closed, and sets a predetermined value larger than the predetermined value for the threshold when the thermostat is open. The determination unit determines that there is a stuck-closed failure in a selector valve when a temperature difference between a coolant temperature from a first coolant temperature sensor and a coolant temperature from a second coolant temperature sensor is larger than or equal to the threshold.