Screw Machine Rotor Pair Geometry for Leakage and Smooth Running
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Solution Overview
Problem
Existing screw machines face challenges in achieving a balance between energy efficiency, smooth running, and cost-effectiveness due to conflicting requirements such as minimizing internal leakages, optimizing rotor profiles, and ensuring manufacturability, which current optimization methods fail to address comprehensively.
Innovation Solution
A rotor pair design with specific geometric configurations for the main and secondary rotors, including defined transverse sections, wrap-around angles, and tooth number ratios, which optimize parameters like relative profile depth, blow hole area, and profile gap length to enhance energy efficiency and smooth running while reducing manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the profile depth of the secondary rotor is increased to minimize internal leakages and improve energy efficiency, then the energy efficiency improves, but the manufacturability and cost-effectiveness deteriorate
Solution Approach 1:
The patent applies parameter changes by optimizing the relative profile depth parameter within a specific range (0.45-0.65) rather than maximizing it indefinitely. This parameter optimization resolves the contradiction by finding the sweet spot where energy efficiency gains are achieved while manufacturability is maintained. The systematic variation and optimization of geometric parameters allows balancing competing requirements.
2Productivity
If the wrap-around angle of the main rotor is increased to improve compression efficiency, then the compression efficiency improves, but the device complexity and manufacturing cost increase
Solution Approach 1:
The patent optimizes the wrap-around angle parameter within a defined range (270°-360°) to achieve compression efficiency improvements while controlling device complexity. By establishing optimal parameter ranges through systematic analysis, the patent resolves the contradiction between performance enhancement and complexity increase.
3Power
If the tooth number ratio is optimized to achieve higher pressure ratios, then the compression performance improves, but the smooth running and reliability deteriorate due to increased internal leakages
Solution Approach 1:
The patent addresses this contradiction by optimizing multiple parameters simultaneously including tooth number ratios, profile depths, and wrap-around angles. The coordinated optimization of these parameters ensures that compression performance is improved while maintaining smooth running characteristics and minimizing internal leakages through balanced geometric configurations.
4Loss of energy
If the profile gap length is reduced to minimize internal leakages, then the energy efficiency improves, but the manufacturing precision requirements increase
Solution Approach 1:
The patent resolves this contradiction by optimizing the profile gap length parameter within specific ranges rather than minimizing it to zero. This parameter optimization approach achieves acceptable energy efficiency while maintaining manufacturability and reasonable precision requirements. The systematic parameter analysis identifies optimal gap dimensions that balance performance and manufacturing feasibility.
Data Source
AI summary
The invention relates to a rotor pair for a compressor block of a screw machine, wherein the rotor pair comprises a secondary rotor that rotates about a first axis and a main rotor that rotates about a second axis, wherein the number of teeth of the main rotor is 3 and the number of teeth of the secondary rotor is 4. The relative profile depth of the secondary rotor is at least 0.5, preferably at least 0.515, and at most 0.65, preferably at most 0.595. rk1 is an addendum circle radius drawn around the outer circumference of the secondary rotor and rf1 is a dedendum circle radius starting at the profile base of the secondary rotor, wherein the ratio of the axis distance of the first axis from the second axis and the addendum circle radius rk1 is at least 1.636, and at most 1.8, preferably at most 1.733.