Screw Compressor Axial Suction Port Contour Optimization

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Solution Overview

Problem

Existing screw compressors face challenges in enhancing energy and volume efficiency due to inadequate contour shapes of axial suction ports, which can lead to reduced suction flow rates and efficiency when either the opening area or time is insufficient or excessive.

Innovation Solution

A screw compressor design featuring an axial suction port contour line that includes a line along the male lobe profile and a line along the female lobe profile, with specific displacement angles to optimize the working chamber volume, ensuring efficient gas suction and minimizing backflow.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the axial suction port opening area is increased to ensure sufficient suction flow rate, then the suction flow rate improves, but the compressed gas flows back during compression process, reducing volume efficiency

Engineering Contradiction:
Improvesuction flow rateVSAvoidvolume efficiency
Core Design Contradiction:
ProductivityVSLoss of energy

Solution Approach 1:

The suction port opening is designed to dynamically change its effective area during the compression cycle. The contour line configuration causes the opening to be larger during the suction stroke (when working chamber volume is increasing) and effectively smaller during the compression stroke (when working chamber volume is decreasing), preventing backflow while maintaining adequate suction capacity

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The suction port opening is configured to close before the working chamber reaches its minimum volume. By setting the contour line to close the opening at a predetermined position before maximum compression, the design prevents compressed gas from flowing back through the suction port during the compression process

Inventive Principle:
Principle #10Preliminary action

2Productivity

If the axial suction port opening time is extended to increase suction amount, then the suction flow rate improves, but the compression process is affected, reducing volume efficiency

Engineering Contradiction:
Improvesuction flow rateVSAvoidopening time
Core Design Contradiction:
ProductivityVSDuration of action of moving object

Solution Approach 1:

The suction port opening dynamically adjusts its effective duration through the contour line design. The opening remains large during the suction phase when working chamber volume increases, but closes early when compression begins, creating an optimal time profile that maximizes suction while minimizing interference with compression

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The contour line configuration causes the suction port to close in advance before the working chamber reaches minimum volume. This preliminary closing action prevents compressed gas from entering the suction port during compression, maintaining volume efficiency while still allowing adequate suction time

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP2390508B1Suction opening of a screw compressor
Publication Date: 2018.03.28 HITACHI IND EQUIP SYST CO LTD
  • EP2390508B1 patent drawingFigure 1A~1B
  • EP2390508B1 patent drawingFigure 2~3
  • EP2390508B1 patent drawingFigure 4A~4B

AI summary

A screw compressor includes a casing (3) forming a bore (4) for accommodating a male rotor (1) and a female rotor (2) of which lobes mesh with each other, an axial suction port (11) on a suction side of the casing, and a delivery port on a delivery side, the axial suction port configured by a contour line including a line (15) along a male lobe profile and a line (18) along a female lobe profile, and the line (15) along the male lobe profile disposed at a predetermined displacement angle (Δf1) toward a rotational direction of the male rotor from a following side contour line position of a male lobe groove (5) at which position the volume of a working chamber (9) formed by the male lobe groove of the male rotor, a female lobe groove (6) of the female rotor and the bore is maximum.