Scroll Compressor Wall Inclined Section Design

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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 difficulties lead to burrs or sagging, causing shape deviations and excessive contact between tooth tips and bottoms, which affects seal performance.

Innovation Solution

Incorporating inclined sections that continuously reduce the inter-facing-surface distance between end plates and walls, along with flat sections and inclination moderation shapes, such as chamfered designs, to facilitate smooth machining and prevent excessive contact and seal restriction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If step sections are provided on the walls and end plates to perform three-dimensional compression, then displacement and compressor capacity are increased, but fluid leakage at the step sections becomes large and stress concentration reduces strength

Engineering Contradiction:
Improvecompressor capacityVSAvoidfluid leakage
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent replaces the conventional stepped (angular) structure with a curved inclined section structure. The inclined section continuously reduces the inter-facing-surface distance from the outer circumferential side toward the inner circumferential side, eliminating abrupt step transitions. This curvature approach reduces fluid leakage paths while distributing stress more evenly compared to the sharp corners of stepped structures.

Inventive Principle:
Principle #14Spheroidality (Curvature)

2Device complexity

If the inclined section and flat section are connected without modification, then the structure is simple, but the shape discontinuously changes causing machining difficulties and generation of burrs or sagging

Engineering Contradiction:
Improvestructure simplicityVSAvoidshape accuracy
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The patent introduces an inclination moderation shape (curved transition) at the connecting section between the inclined section and the flat section. This curved transition eliminates the abrupt angular change, enabling smooth continuous machining without discontinuous shape changes. The moderation shape prevents burr and sagging generation by providing a gradual transition zone that machining tools can follow smoothly.

Inventive Principle:
Principle #14Spheroidality (Curvature)

3Reliability

If a tip seal is installed in the groove section to seal fluid, then seal performance is improved, but burrs or sagging on the groove bottom inclined connecting section catch the tip seal and restrict its movement

Engineering Contradiction:
Improveseal performanceVSAvoidtip seal movement
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The patent applies the inclination moderation shape (curved transition) specifically to the groove bottom inclined connecting section where the tip seal moves. This curved transition eliminates sharp corners and protrusions that would catch the tip seal, allowing smooth continuous movement of the seal along the groove while maintaining effective sealing contact between the tooth tip and tooth bottom.

Inventive Principle:
Principle #14Spheroidality (Curvature)

4Reliability

If an inclined section with small inclination angle is used to reduce fluid leakage, then seal performance is improved, but the compression ratio decreases

Engineering Contradiction:
Improveseal performanceVSAvoidcompression ratio
Core Design Contradiction:
ReliabilityVSStress or pressure

Solution Approach 1:

The patent transitions from two-dimensional compression (conventional scroll compressor) to three-dimensional compression by incorporating inclined sections on both the walls and end plates. This adds the height dimension to the compression process, allowing the compression ratio to be maintained or enhanced while using smaller inclination angles that reduce fluid leakage. The inclined end plates work together with the inclined walls to achieve the required compression.

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

Data Source

PatentEP3739213B1Scroll fluid machine
Publication Date: 2023.09.20 MITSUBISHI HEAVY IND THERMAL SYST
  • EP3739213B1 patent drawingFigure 1A~1B
  • EP3739213B1 patent drawingFigure 2
  • EP3739213B1 patent drawingFigure 3

AI summary

The present invention includes a wall inclined section (3b1) that continuously reduces, and a wall flat section (3b2) provided in an innermost circumferential part of a wall (3b), and having no change in height. A tooth tip of a wall inclined connecting section (3b4) that connects the wall inclined section (3b1) and the wall flat section (3b2) has an R-chamfered shape formed by moderating and connecting an inclination from the wall flat section (3b2) to the wall inclined section (3b1).