Compressor Stator Fluid Passage for Lubricant Retention

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Solution Overview

Problem

In compressors, high-speed refrigerant gas flow can cause lubricant to be carried out of the compressor along with the refrigerant, leading to a reduction in lubricant storage within the compressor.

Innovation Solution

The compressor incorporates fluid passages with alternating wide and narrow sections on the stator's outer surface, which decelerate the refrigerant gas, causing the lubricant with higher specific gravity to separate and return to the oil reservoir, thereby preventing its loss.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the flow velocity of the refrigerant gas is high, then the compression efficiency is improved, but the lubricant flows out of the compressor along with the refrigerant gas without returning to the oil reservoir

Engineering Contradiction:
Improvecompression efficiencyVSAvoidlubricant loss
Core Design Contradiction:
ProductivityVSLoss of substance

Solution Approach 1:

The fluid passage is segmented into multiple narrow portions and wide portions arranged alternately in the circumferential direction. This segmentation creates multiple flow regions that alternately accelerate and decelerate the refrigerant gas, enabling lubricant separation without reducing overall compression efficiency.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different portions of the fluid passage are designed with different cross-sectional areas (narrow and wide portions) to create localized flow characteristics. The narrow portions accelerate the flow while the wide portions allow lubricant separation, providing spatially varying flow qualities that address both compression efficiency and lubricant retention.

Inventive Principle:
Principle #3Local quality

2Loss of substance

If the lubricant is separated from the refrigerant gas, then the lubricant returns to the oil reservoir, but the refrigerant gas flow velocity is reduced

Engineering Contradiction:
Improvelubricant retentionVSAvoidrefrigerant gas flow velocity
Core Design Contradiction:
Loss of substanceVSSpeed

Solution Approach 1:

The fluid passage is divided into alternating narrow and wide portions that sequentially process the refrigerant gas. The narrow portions maintain high flow velocity for efficient compression, while the wide portions provide conditions for lubricant separation. This segmentation allows the system to achieve both high speed and effective separation.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The refrigerant gas undergoes periodic acceleration and deceleration as it flows through the alternating narrow and wide portions. This periodic flow pattern allows the lubricant to be separated during deceleration phases while maintaining high average flow velocity for efficient compression operation.

Inventive Principle:
Principle #19Periodic action

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 design effectively reduces the amount of lubricant lost with the refrigerant gas, ensuring a consistent lubricant supply and maintaining compressor efficiency.

Implementation Method 1

the lubricant having a larger specific gravity than the fluid cannot be rapidly decelerated, and thus is likely to be separated from the fluid

Methodology Applied
Scientific EffectSpecific gravity separation: Density Gradient

Implementation Method 2

The wide portions (25) each have a larger width in the radial direction of the stator (21) than the narrow portion (26). Thus, the refrigerant gas flowing from the narrow portion (26) into the wide portions (25) is decelerated

Methodology Applied
Scientific EffectFlow deceleration: Diffusion

Implementation Method 3

a joint portion (45) is provided on the outer peripheral surface of the stator (21) and in contact with the inner peripheral surface of the barrel (11) from one end to the other end of the stator (21). the fluid flowing in the direction of rotation of the rotor (22) through the fluid passage (24) is blocked by the joint portion (45)

Methodology Applied
Scientific EffectPhysical blockage: Physical Containment

Data Source

PatentEP4148276B1compressor
Publication Date: 2025.05.21 DAIKIN INDUSTRIES LTD
  • EP4148276B1 patent drawingFigure 1
  • EP4148276B1 patent drawingFigure 2
  • EP4148276B1 patent drawingFigure 3

AI summary

Between the outer peripheral surface of a stator (21) and the inner peripheral surface of a barrel (11) in a compressor (1), a fluid passage (24) extending from one end to the other end of the stator (21) and through which the fluid discharged from a compression mechanism (30) passes is provided. The fluid passage (24) has a plurality of wide portions (25) arranged in the circumferential direction of the stator (21) and a narrow portion (26) provided between adjacent wide portions (25), the narrow portion (26) having a smaller width in the radial direction of the stator (21) than each of the wide portion (25).