Scroll Compressor Torsional Moment Balancing via Chamber Volume Asymmetry

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Solution Overview

Problem

Existing scroll compressors face performance degradation and abnormal noise due to the orbiting scroll's rocking motion caused by torsional moments, which conventional solutions attempt to mitigate by introducing gaps or adjustments that ultimately reduce performance and increase noise variations.

Innovation Solution

A scroll compressor design with a fixed and orbiting scroll featuring step portions in the spiral direction, where the volumes of compression chambers on the concave-surface sides of the fixed and orbiting scrolls are differentiated to balance torsional moments, preventing rocking motion without pre-setting gaps, thereby stabilizing the orbiting scroll's behavior and reducing noise.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the orbiting scroll is allowed to orbitally revolve around the fixed scroll with a rotation preventing mechanism, then compression function is achieved, but the orbiting scroll rotates in a rocking manner due to dimensional tolerances and assembly tolerances causing performance degradation and abnormal noise

Engineering Contradiction:
Improvecompression functionVSAvoidabnormal noise and performance degradation
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent introduces asymmetry by making the compression chamber volumes unequal. Specifically, at least one compression chamber has a volume different from the others, creating a volume difference that generates a counteracting torsional moment to stabilize the orbiting scroll and prevent rocking motion caused by tolerances.

Inventive Principle:
Principle #4Asymmetry

Solution Approach 2:

The patent changes the volume parameter of compression chambers to create a deliberate imbalance. By adjusting the volume of at least one compression chamber relative to others, a torsional moment is generated that counteracts the rocking motion, thereby stabilizing the orbiting scroll without requiring additional mechanical constraints.

Inventive Principle:
Principle #35Parameter changes

2Object-generated harmful factors

If conventional techniques cut the wrap faces or adjust pin positions to prevent rocking motion, then abnormal noise is reduced, but performance is reduced and operation noise variations increase

Engineering Contradiction:
Improveabnormal noiseVSAvoidperformance
Core Design Contradiction:
Object-generated harmful factorsVSReliability

Solution Approach 1:

Instead of modifying mechanical components through cutting or repositioning, the patent changes the volume parameter of compression chambers. This creates a torsional moment that stabilizes the orbiting scroll while maintaining the original mechanical structure and avoiding performance loss.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent converts the harmful effect of tolerance-induced rocking into a beneficial stabilization mechanism. By creating a deliberate volume imbalance in compression chambers, the resulting torsional moment counteracts the rocking motion, turning the problem of tolerance sensitivity into a solution that actively prevents abnormal noise.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This configuration effectively prevents performance degradation and noise issues by balancing torsional forces within the compressor, maintaining high performance and reducing operational noise without the need for additional gaps or adjustments.

Implementation Method 1

a volume V1 of a compression chamber formed on a concave-surface side of the fixed spiral wrap of the fixed scroll when intake is cut off and a volume V2 of a compression chamber formed on a concave-surface side of the orbiting spiral wrap of the orbiting scroll are different... balancing a torsional moment in the orbital direction or the opposite direction caused by various forces and applied to the orbiting scroll depending on the operating conditions by a torsional moment in the direction opposite thereto caused by the pressure of the compression chamber having a larger volume

Methodology Applied
Scientific EffectTorsional moment balancing: Torque

Data Source

PatentEP2426359B1Scroll compressor
Publication Date: 2019.06.12 MITSUBISHI HEAVY IND LTD
  • EP2426359B1 patent drawingFigure 1
  • EP2426359B1 patent drawingFigure 2
  • EP2426359B1 patent drawingFigure 3

AI summary

An object is to provide a scroll compressor capable of preventing degradation in performance and the occurrence of abnormal noise due to a torsional moment applied to an orbiting scroll, by utilizing the structural advantages of so-called stepped scroll compressors. In a so-called stepped scroll compressor (1), in a pair of compression chambers (16) arranged in a point-symmetrical configuration among a plurality of compression chambers (16), the volume V1 of the compression chamber (16) formed on the ventral-surface side of the fixed spiral wrap (14B) of the fixed scroll (14) when intake is cut off and the volume V2 of the compression chamber (16) formed on the ventral-surface side of the orbiting spiral wrap (15B) of the orbiting scroll (15) are different from each other.