Scroll Fluid Machine Tip Seal Groove Positioning

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Solution Overview

Problem

The stepped scroll compressor experiences significant fluid leakage and reduced strength due to concentrated stress at step sections, and machining errors can lead to contact between the tip seal and step sections, causing performance deterioration.

Innovation Solution

A scroll fluid machine with inclined sections that continuously reduce the inter-facing-surface distance between end plates, and a machining method that forms a groove section on the center side of the wall to prevent contact between the tip seal and step sections, reducing fluid leakage and abrasion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If step sections are provided on the walls to enable three-dimensional compression and increase compressor capacity, then displacement and compressor capacity are improved, but fluid leakage at the step sections increases and strength is reduced due to stress concentration

Engineering Contradiction:
Improvecompressor capacityVSAvoidfluid leakage
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent replaces the conventional stepped (angular) structure with a continuously curved inclined section. The inclined section has a continuous curvature that eliminates sharp corners and steps, allowing fluid to flow smoothly without leakage while maintaining the compression function. This curved geometry resolves the contradiction by providing both the height reduction needed for compression and the smooth surface needed to prevent fluid leakage.

Inventive Principle:
Principle #14Spheroidality (Curvature)

2Reliability

If inclined sections are provided to eliminate step sections and reduce fluid leakage, then fluid leakage is reduced, but machining difficulty increases and machining accuracy decreases

Engineering Contradiction:
Improvefluid leakageVSAvoidmachining difficulty
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The inclined section is designed with a specific continuous curvature that, while machining-challenging, can be manufactured using standard CNC machining processes. The curvature is optimized to balance machining feasibility with the requirement to eliminate steps. The groove section positioning further aids manufacturing by providing a reference feature for aligning the inclined section geometry.

Inventive Principle:
Principle #14Spheroidality (Curvature)

Solution Approach 2:

The groove section is formed in advance at a predetermined position before final machining of the inclined section. This preliminary action provides a reference feature that guides subsequent machining operations, ensuring that the inclined section is machined with the correct orientation and curvature, thereby reducing overall machining difficulty and improving accuracy.

Inventive Principle:
Principle #10Preliminary action

3Ease of manufacture

If the groove section is positioned to face the step section, then machining is simpler, but the tip seal comes into contact with the step section causing clearance generation and fluid leakage

Engineering Contradiction:
Improvemachining simplicityVSAvoidfluid leakage
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The solution moves the groove section in the thickness direction (perpendicular dimension) rather than keeping it in the same plane as the step section. By positioning the groove section on the center side in the thickness direction with respect to the position facing the step section, the tip seal is prevented from contacting the step section while the groove still serves its sealing function. This dimensional shift resolves the contradiction between machining simplicity and preventing fluid leakage.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Data Source

PatentEP3754197B1Scroll fluid machine and machining method of scroll member
Publication Date: 2024.12.25 MITSUBISHI HEAVY IND THERMAL SYST
  • EP3754197B1 patent drawingFigure 1A~1B
  • EP3754197B1 patent drawingFigure 2
  • EP3754197B1 patent drawingFigure 3

AI summary

A tip seal groove (3d) is formed on a tooth tip of a fixed scroll, and stores a tip seal (7). A step section (9a) is provided on a tooth bottom corner (9) at a base of a wall (5b) of an orbiting scroll facing a tooth tip corner (8) of a wall (3b) of the fixed scroll. The tip seal groove (3d) is formed on the center side in the thickness direction of the wall (3b) with respect to a position facing the step section (9a). That is, the bank width (Ta) of a tooth tip of the wall (3b) is formed larger than the step section width (Sw) of the step section (9a).