Heat Pump Lubricant Flushing for Compressor Oil Return
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Solution Overview
Problem
Lubricant accumulation in the refrigerant subsystem of a vehicle's heat pump reduces compressor efficiency and durability, as it adheres to components and disrupts heat transfer, with existing solutions like oil separators offering limited relief.
Innovation Solution
Activating a pump in a heat pump system when the vehicle is electrically coupled to a stationary power grid to flush lubricant from undesirable locations back to the compressor, utilizing a flushing mode that can be either full or partial based on operational conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pump is activated to flush lubricant from the heat pump system, then heat pump efficiency and durability are improved, but energy consumption increases
Solution Approach 1:
The pump is activated periodically rather than continuously to flush lubricant from the heat pump system. The control system monitors lubricant accumulation conditions and triggers pump operation only when flushing is necessary, thereby maintaining system reliability while minimizing energy consumption during non-flushing periods.
Solution Approach 2:
The system uses the existing pump infrastructure already present in the heat pump system for dual purposes: normal refrigerant circulation and lubricant flushing. This eliminates the need for additional dedicated flushing equipment and reduces overall energy consumption by utilizing existing components.
2Duration of action of moving object
If lubricant is allowed to accumulate in refrigerant subsystem components, then the compressor can operate continuously without interruption, but heat transfer characteristics deteriorate and compressor degradation occurs
Solution Approach 1:
The control system continuously monitors system conditions including lubricant accumulation indicators, heat transfer efficiency, and compressor performance. Based on this feedback, the system determines when lubricant flushing is necessary to maintain optimal performance, allowing continuous operation only when performance thresholds are met.
Solution Approach 2:
The system performs lubricant flushing proactively before significant accumulation occurs and before performance degradation becomes severe. By detecting early signs of lubricant migration and initiating flushing preemptively, the system maintains continuous operational capability while preventing efficiency loss.
3Reliability
If an oil separator is used to delay lubricant accumulation, then lubricant return to compressor is improved, but the system complexity increases and undesirable conditions persist
Solution Approach 1:
The pump serves multiple functions: normal refrigerant circulation during operation and lubricant flushing when needed. This multi-functionality eliminates the need for separate dedicated lubricant management components, reducing system complexity while maintaining effective lubricant return to the compressor.
Solution Approach 2:
The system changes operational parameters (pump activation state, flow direction, system mode) to achieve lubricant flushing rather than adding physical components. By manipulating existing system parameters dynamically, the system achieves oil separation functionality without increasing hardware complexity.
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
Improves heat pump efficiency and durability by effectively redistributing lubricant within the system, preventing accumulation and maintaining optimal performance.
Implementation Method 1
Activating a pump in a heat pump system when the vehicle is electrically coupled to a stationary power grid to flush lubricant from undesirable locations back to the compressor
Implementation Method 2
The refrigerant may travel throughout the heat pump system and transfer heat between two or more different locations
Implementation Method 3
The heat pump may include a compressor for pressurizing refrigerant
Data Source
AI summary
Methods and system for managing lubricant within a vapor compression heat pump are presented. In one example, lubricant may be flushed from selected areas of a heat pump to other areas of the heat pump where lubricant is desired. The lubricant may be flushed in full flushing mode or in a partial flushing mode.