Oil level detection device and refrigerating air conditioner equipped with same
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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 compressor environments and are prone to errors from temperature and pressure changes, leading to costly and labor-intensive compressor replacements.
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 determination of oil depletion by comparing measurement values before and after signal output.
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 patent uses the compressor housing as an intermediary medium to transmit thermal information from the oil and gas refrigerant to the detection sensor. The sensor is installed on the outer surface of the compressor housing rather than inside, allowing it to detect temperature differences caused by oil presence without being exposed to harsh internal conditions. The housing acts as a thermal conductor that mediates between the internal fluid dynamics and the external sensor.
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 (only several degrees C) between oil and gas portions
Solution Approach 1:
The control unit performs preliminary action by controlling the compressor to operate at specific operating conditions that maximize the temperature difference between oil and gas portions before the detection occurs. By pre-establishing optimal operating conditions, the system ensures that the temperature differential is sufficient for accurate detection when the sensor measures.
Solution Approach 2:
The system changes operational parameters of the compressor (such as suction temperature, pressure, or flow rate) to create conditions that amplify the temperature difference between oil and gas portions. By adjusting these parameters, the system transforms the small temperature difference into a detectable signal range for the external sensor.
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 influence from compressor operation state changes and environment state changes
Solution Approach 1:
The control unit implements feedback by continuously monitoring the compressor's operation state (such as suction temperature, discharge pressure, or current draw) and using this information to compensate for variations in the temperature difference signal. The system adjusts its interpretation of sensor readings based on real-time operational feedback, maintaining accuracy despite changing 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
Enables correct detection of oil depletion, reducing maintenance costs and labor by minimizing erroneous readings and improving reliability in harsh compressor environments.
Implementation Method 1
the difference in heat transfer characteristics in a gas and in a liquid
Implementation Method 2
the difference in temperature between an oil portion and a gas portion appearing on an outer surface of the compressor
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
Provided is an oil level detection device to be mounted on a refrigerating and air-conditioning apparatus (1), the oil level detection device being configured to detect an oil level of oil accumulated inside a compressor (21) forming the refrigerating and air-conditioning apparatus (1). The oil level detection device includes an oil level detection unit (70) installed on an outer surface of the compressor (21) and configured to detect a temperature of an installation position, a sensor output unit (35f) configured to output, to the refrigerating and air-conditioning apparatus (1), a signal to change an operation state of the refrigerating and air-conditioning apparatus (1), and a determination unit (35b) configured to determine depletion of the oil accumulated inside the compressor (21) based on measurement values obtained by the oil level detection unit (70) at least after an output of the signal from the sensor output unit (35f).