Variable-Speed Scroll Compressor Oil Flow Regulating Device
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Solution Overview
Problem
Variable-speed refrigerating scroll compressors face challenges in maintaining a proper oil circulation ratio (OCR) level due to variations in operational speed, leading to inefficiencies and potential wear from excessive oil injection.
Innovation Solution
A scroll compressor design featuring an oil flow regulating device with a movable oil flow regulating member that controls oil flow through an oil passage opening based on the compressor's speed, ensuring optimal OCR levels without excessive wear or oil starvation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional oil injectors are used to maintain OCR level, then sealing between pockets is improved, but device complexity and cost increase
Solution Approach 1:
The system uses the refrigerant flow itself to drag oil droplets from the oil sump to the compression pockets, eliminating the need for separate oil injectors. The refrigerant naturally performs the oil delivery function through its flow path and suction action.
Solution Approach 2:
The refrigerant serves multiple functions: it cools the compression pockets, drives the orbiting scroll motion, and simultaneously transports oil droplets to maintain sealing. This multi-functionality eliminates dedicated oil injection equipment.
2Reliability
If oil delivery is increased to maintain OCR at low speed, then sealing is improved, but thermodynamic efficiency decreases due to excessive oil
Solution Approach 1:
The oil delivery mechanism is inherently dynamic, with oil droplet transport varying automatically with refrigerant flow speed. At low compressor speeds, less oil is delivered naturally; at high speeds, more oil is delivered, matching the varying sealing requirements without manual intervention.
Solution Approach 2:
The system changes the delivery parameter (oil flow rate) by changing the refrigerant flow velocity, which varies with compressor operating speed. This automatic parameter adjustment ensures optimal OCR at all speeds without external control.
3Ease of manufacture
If constant oil delivery is used, then lubrication is simplified, but OCR becomes excessive at high speed leading to energy loss
Solution Approach 1:
The oil delivery occurs periodically through the compression cycle, with oil droplets being picked up during suction and delivered during compression. This periodic action naturally adjusts oil quantity to match the varying refrigerant flow and sealing needs at different operating 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
The solution effectively regulates oil flow to maintain optimal OCR levels across varying speeds, improving the compressor's efficiency, reducing wear, and ensuring reliable lubrication of critical components.
Implementation Method 1
the amount of oil droplets dragged by the refrigerant flow
Implementation Method 2
an orbiting scroll and a fixed scroll define a plurality of pockets, also named compression chambers, in which a refrigerant is being compressed
Data Source
AI summary
A scroll compressor comprising a compressor casing; a compression unit including a fixed scroll and an orbiting scroll defining a compression volume; an oil sump; a drive shaft including a driving portion coupled with the orbiting scroll; a variable-speed electric motor configured to rotatably drive the drive shaft; an oil injection system including an oil feed channel fluidly connected to the oil sump and extending over the entire length of the drive shaft, and oil injection means provided on the orbiting scroll and configured to deliver oil from the oil feed channel to the compression volume; and an oil flow regulating device configured to regulate an oil flow from the oil feed channel to the oil injection means.