Compressor Shaft Vent for Excess Lubricant Return and Motor Cooling
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Solution Overview
Problem
Variable-speed compressors face the challenge of oversupplying lubricant at higher speeds due to fixed-displacement pumps, leading to inefficiencies and potential entrainment of lubricant with the gas, which can affect performance and cooling.
Innovation Solution
A vent is provided within the shaft of the compressor, allowing excess lubricant to be returned to the sump, positioned to avoid entrainment with gas and provide cooling to the motor by contacting the stator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed-displacement lubricant pump is used in a variable-speed compressor, then the pump can provide consistent lubricant flow, but excess lubricant is oversupplied at higher speeds leading to inefficiency and potential entrainment with gas
Solution Approach 1:
The patent extracts the excess lubricant from the main lubricant flow path by providing a separate vent passage within the shaft. This vent passage allows the lubricant pump to continue operating at fixed displacement while excess lubricant is diverted and returned to the sump, preventing energy waste and gas entrainment issues.
Solution Approach 2:
The shaft is designed with multi-functionality, serving both as a structural component and as a lubricant management system. The vent passage within the shaft allows the same component to handle both normal lubricant delivery and excess lubricant removal, eliminating the need for additional separate systems.
2Device complexity
If a fixed-displacement lubricant pump is used in a variable-speed compressor, then the pump structure can be simple, but lubricant can be oversupplied at higher speeds causing harmful effects
Solution Approach 1:
The vent passage acts as an intermediary channel within the shaft that mediates between the lubricant pump output and the sump. It provides a controlled path for excess lubricant to return to the sump, preventing the harmful effect of lubricant entrainment with compressed gas while maintaining the simplicity of the fixed-displacement pump structure.
3Loss of substance
If the vent is positioned above the rotor-stator assembly, then excess lubricant can be removed, but the lubricant may become entrained with the gas in the compressor
Solution Approach 1:
The vent outlet is positioned at a specific location on the shaft surface that is below the rotor-stator assembly, creating a localized discharge point where lubricant can be removed without entering the gas compression zone. This positioning ensures that the lubricant removal function is achieved while avoiding the harmful effect of gas entrainment.
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 vent system effectively manages lubricant supply, ensuring adequate lubrication at all speeds while preventing lubricant entrainment and providing supplemental cooling to the motor.
Implementation Method 1
the vent receives lubricant after other surfaces due to centrifugal force within the compressor
Data Source
AI summary
A compressor includes a lubricant pump and a shaft having a lubricant vent extending through the shaft. The vent has an outlet, which can be provided below a stator-rotor assembly of a motor of the compressor. The shaft can be used in a variable speed compressor to convey excess lubricant when the pump is over-supplying lubricant due to operation at speeds greater than the minimum speed. The vent can be positioned at a center of the shaft. The outlet of the vent can direct gas and/or lubricant onto windings of the stator so as to provide cooling.