Screw Compressor Rotor Tooth Profile Optimization for Leakage Reduction

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Solution Overview

Problem

Constant frequency screw compressors have limited compression performance and a narrow application range, and the rotor structure of both constant frequency and inverter screw compressors often results in refrigerant leakage due to unreasonable profile configurations.

Innovation Solution

A rotor structure for screw compressors with a female rotor featuring a tooth profile formed by sequentially connecting specific arc segments and an envelope, optimizing the tooth profile to reduce pressure differences and enhance compatibility with inverter screw compressors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a constant frequency screw compressor uses a fixed rotor profile, then the compression performance is optimized for a specific operating point, but the application range becomes narrow and performance deteriorates at variable speeds

Engineering Contradiction:
Improvecompression performanceVSAvoidapplication range
Core Design Contradiction:
ProductivityVSAdaptability or versatility

Solution Approach 1:

The patent applies parameter changes by modifying the tooth profile geometry parameters (arc radii, envelope curves, connection points) to create an optimized profile that maintains compression performance across variable speeds. The specific parameter changes include adjusting the arc segments (ab, bc, cd, de, ea2, a2a3) and their connecting envelopes to achieve better adaptability for inverter compressors while reducing refrigerant leakage.

Inventive Principle:
Principle #35Parameter changes

2Ease of manufacture

If a standard rotor profile is used in inverter screw compressors, then manufacturing is simplified, but compression performance is reduced due to variable rotation speeds

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidcompression performance
Core Design Contradiction:
Ease of manufactureVSProductivity

Solution Approach 1:

The patent modifies the standard rotor profile parameters by changing the arc radii (R2t, R3, R4, R5, R6, R7, R8), envelope parameters (k, φ1, A), and connection point coordinates to create an optimized profile that maintains manufacturing feasibility while significantly improving compression performance for variable speed inverter compressors.

Inventive Principle:
Principle #35Parameter changes

3Device complexity

If a conventional tooth profile configuration is used, then the rotor structure is simple, but substantial refrigerant leakage occurs during compression

Engineering Contradiction:
Improverotor structure complexityVSAvoidrefrigerant sealing
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent addresses refrigerant leakage by optimizing the tooth profile parameters, specifically adjusting the arc segments and their connections to improve sealing between rotor teeth. The parameter changes in the tooth profile geometry create better clearance control and sealing surfaces, reducing refrigerant leakage without significantly increasing rotor structure complexity.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3719321B1Screw compressor rotor structure and variable-frequency screw compressor having same
Publication Date: 2025.05.21 GREE ELECTRIC APPLIANCE INC OF ZHUHAI
  • EP3719321B1 patent drawingFigure 1
  • EP3719321B1 patent drawingFigure 2
  • EP3719321B1 patent drawingFigure 3

AI summary

The present disclosure provides a rotor structure of a screw compressor and an inverter screw compressor with the same. The rotor structure of a screw compressor includes: a female rotor comprising a female rotor body, wherein the female rotor body is provided with a plurality of female teeth, and a tooth profile is formed between tooth crests of two adjacent female teeth of the female rotor body, and the tooth profile is formed by sequentially connecting an arc segment a1b, an envelope bc, an arc segment cd, an arc segment de, an arc segment ea2, an arc segment a2a3 from front to rear along a counterclockwise direction, wherein centers of the arc segment cd and the arc segment de are respectively located on both sides of the tooth profile. In this way, the tooth profile is effectively optimized, the configuration of the tooth profiles is more reasonable, which reduces a rotation speed of the rotor structure at the same flow rate. In particular, the inverter screw compressor with the tooth-profile of the rotor structure is adapted to effectively reduce the leakage of the compressor and improve the compression energy efficiency and application of the compressor.