Heat pump
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Solution Overview
Problem
Existing heat pumps face challenges in accurately detecting abnormalities in the oil return channel due to low accuracy in pressure sensor readings, especially during startup and when compressors are operating intermittently, leading to delayed detection of issues.
Innovation Solution
Incorporating first and second pressure loss members, such as capillaries, in the oil return channel and using a control device to adjust compressor output based on pressure sensor readings that exceed suction or fall below discharge pressure, allowing for early detection of abnormalities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pressure sensor is used to detect oil return channel abnormalities, then detection can be performed, but detection accuracy is low because pressure near discharge pressure is detected both when oil normally flows and when capillary is clogged
Solution Approach 1:
A temperature sensor is introduced as an intermediary measurement device to detect oil temperature in the oil return channel. This alternative sensor provides discriminatory information that can distinguish between normal operation and capillary clogging, overcoming the limitation of the pressure sensor which cannot differentiate between these states when pressure is near discharge pressure.
2Measurement precision
If oil temperature in oil return channel is used for abnormality detection, then abnormality can be detected, but detection cannot be performed for a while after start-up when large amount of oil is stored in oil separator
Solution Approach 1:
The system performs preliminary detection using pressure sensor data before temperature detection becomes reliable. During the initial period after start-up when temperature-based detection is not yet feasible, the pressure sensor provides early abnormality detection capability. Once the oil temperature stabilizes and becomes reliable for detection, the system transitions to temperature-based detection for more accurate abnormality identification.
3Measurement precision
If temperature sensors are disposed near compressors on branch paths, then oil temperature can be detected, but no temperature difference occurs for a while after compressor stops due to residual heat
Solution Approach 1:
The system waits for a predetermined period after compressor operation changes before performing temperature difference-based abnormality detection. This preliminary waiting period allows residual heat to dissipate and temperature differences to stabilize, ensuring that subsequent temperature measurements accurately reflect actual oil flow conditions rather than transient thermal effects.
4Device complexity
If single pressure sensor is used in oil return channel, then simple configuration is achieved, but accurate abnormality detection cannot be performed
Solution Approach 1:
The detection system is segmented into multiple independent sensing points: a pressure sensor for initial and continuous monitoring, and a temperature sensor for confirmed abnormality detection. This segmentation allows the system to use the simple pressure sensor for routine monitoring while introducing temperature measurement only when needed for accurate abnormality confirmation, thereby maintaining overall system simplicity while improving detection accuracy.
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 configuration enables accurate and timely detection of oil return channel abnormalities, improving operational reliability and reducing downtime by distinguishing normal from abnormal conditions.
Implementation Method 1
first and second pressure loss members disposed in portions of the oil return channel at an oil separator side and a compressor side relative to the pressure sensor
Data Source
AI summary
An exemplary heat pump (10) includes: a compressor (16A, 16B) that discharges refrigerant; an oil separator (30) that separates oil from the refrigerant discharged from the compressor; an oil return channel (80) that returns the oil separated by the oil separator to the compressor; a pressure sensor (86A, 86B) that detects a pressure in the oil return channel; a first pressure loss member (84A, 84B) and a second pressure loss member (88A, 88B) disposed in portions of the oil return channel at an oil separator side and a compressor side relative to the pressure sensor; and a control device that increases an output of the compressor in a case where a pressure detected by the pressure sensor exceeds a suction pressure of the compressor and less than a discharge pressure of the compressor.