Air Conditioner Oil Return Valve Control to Prevent Compressor Burn-In
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Solution Overview
Problem
In conventional air conditioners, when one outdoor unit performs a cooling operation, high pressure applied to the stopped outdoor unit causes refrigerant and oil accumulation, leading to potential compressor burn-in due to oil exhaustion.
Innovation Solution
The air conditioner includes an oil return valve control system that prevents high pressure from being applied to the stopped outdoor unit, allowing refrigerant and oil to be sent to the operating unit's suction side, maintaining sufficient oil levels and preventing burn-in.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the oil return valve is opened to return oil to the compressor suction side, then oil can be maintained in the operating unit, but high pressure causes refrigerant and oil to accumulate in the stopped outdoor unit
Solution Approach 1:
A three-way valve is introduced as an intermediary device to control the oil return path. It selectively connects the oil return line to either the operating outdoor unit or the stopped outdoor unit based on system conditions, preventing harmful accumulation while ensuring proper oil return to the operating compressor
Solution Approach 2:
The system dynamically adjusts the oil return configuration based on the operational state of outdoor units. The three-way valve changes connection states according to whether units are operating or stopped, adapting the oil return path to current system conditions to prevent both accumulation and burn-in
2Productivity
If high pressure is applied to the discharge side of the oil return valve in the stopped outdoor unit, then oil can be pushed back to the operating unit, but refrigerant and oil accumulate in the stopped outdoor unit
Solution Approach 1:
The three-way valve acts as a mediator that redirects the high pressure from the operating unit's oil return line away from the stopped unit's discharge side, preventing the pressure-driven accumulation of refrigerant and oil in the stopped unit while still enabling effective oil return through the controlled path
3Quantity of substance
If the oil return valve remains closed to prevent accumulation in the stopped outdoor unit, then refrigerant and oil do not accumulate, but the operating outdoor unit may experience oil exhaustion
Solution Approach 1:
The system dynamically switches the three-way valve position based on real-time operational status. When one outdoor unit stops, the valve automatically redirects oil return to that unit, ensuring continuous oil supply to operating compressors while preventing accumulation in stopped units, thus resolving the contradiction between preventing accumulation and avoiding oil exhaustion
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 solution effectively prevents refrigerant and oil accumulation in stopped outdoor units, ensuring the operating compressor maintains sufficient oil levels, thereby preventing burn-in and ensuring continuous operation.
Implementation Method 1
a part of the oil on the discharge side of the compressor is sent through the oil return pipe to the suction side of the compressor due to a pressure difference
Implementation Method 2
a GHP compressor to be driven by a gas engine
Data Source
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AI summary
There is provided an air conditioner in which when one outdoor unit is performing a cooling operation, oil of the operating outdoor unit can be kept, and burn-in of a compressor due to oil exhaustion during the operation can be prevented. When the cooling operation is performed only by one GHP outdoor unit 2 in the GHP outdoor unit 2 and an EHP outdoor unit 3 and the other EHP outdoor unit 3 is stopped, a GHP control section 100 or an EHP control section 101 determines whether or not an oil level lowers below a certain level, on a basis of a detection value from a GHP oil level sensor 106 of the operating GHP outdoor unit 2, and when the control section determines that the oil level lowers below the certain level, the control section executes control to open an oil return valve 34 of the operating GHP outdoor unit 2.