Compressor Oil Level Sensing via External Temperature Change
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Solution Overview
Problem
Existing oil level detection sensors in refrigeration and air-conditioning systems face challenges in accurately detecting oil depletion due to harsh installation environments within compressors, leading to erroneous readings and high maintenance costs.
Innovation Solution
An oil level detection device with an oil level detection sensor installed at a predetermined height on the compressor, capable of detecting temperature changes and outputting signals to adjust compressor suction temperature, allowing for accurate oil level determination by comparing pre- and post-signal measurement values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the oil level detection sensor is installed inside the compressor, then the detection precision is improved due to direct contact with oil and gas refrigerant, but the reliability deteriorates due to harsh temperature and pressure conditions causing sensor failure
Solution Approach 1:
The detection function is segmented from the compressor body. The oil level detection sensor is installed on the outer surface of the compressor shell rather than inside, separating the sensor from the harsh internal environment while maintaining detection capability through thermal conduction through the shell wall.
Solution Approach 2:
The compressor shell wall acts as an intermediary medium, transmitting thermal information from the internal oil and gas refrigerant to the sensor on the outer surface. This allows indirect measurement without exposing the sensor to extreme conditions.
2Reliability
If the oil level detection sensor is installed outside the compressor, then the reliability is improved by avoiding harsh internal conditions, but the measurement precision deteriorates due to small temperature difference of only several degrees C between oil and gas portions
Solution Approach 1:
The detection method changes from measuring small temperature differences (several degrees C) to detecting temperature changes over time. By monitoring the temporal variation of temperature at the sensor position, the system can identify oil depletion even when spatial temperature differences are minimal.
Solution Approach 2:
The system performs preliminary temperature measurements to establish a baseline before oil depletion occurs. By comparing current temperature readings with historical data or expected values, the system can detect deviations indicating oil depletion before the temperature difference becomes significant.
3Ease of repair
If the oil level detection sensor is installed outside the compressor, then the ease of repair is improved by avoiding compressor disassembly, but the measurement precision deteriorates due to sensor being influenced by compressor operation state and environment state changes
Solution Approach 1:
The system continuously monitors temperature readings and compares them with expected values based on compressor operation state. When deviations occur that cannot be explained by normal operation variations, the system flags potential sensor errors or oil depletion, enabling adaptive compensation for environmental influences.
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 reliable detection of oil depletion, reducing maintenance costs and preventing erroneous readings by accurately differentiating between oil presence and depletion based on temperature changes.
Implementation Method 1
the difference in heat transfer characteristics in a gas and in a liquid
Data Source
AI summary
Provided is an oil level detection device to be mounted on a refrigerating and air-conditioning apparatus, the oil level detection device being configured to detect an oil level of oil accumulated inside a compressor forming the refrigerating and air-conditioning apparatus. The oil level detection device includes an oil level detection unit installed on an outer surface of the compressor and configured to detect a temperature of an installation position, a sensor output unit configured to output, to the refrigerating and air-conditioning apparatus, a signal for changing an operation state of the refrigerating and air-conditioning apparatus, and a determination unit configured to determine depletion of the oil accumulated inside the compressor based on measurement values obtained by the oil level detection unit at least after an output of the signal to be output from the sensor output unit.