Scroll Compressor Orbiting Scroll Offset for Better Suction Flow

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Solution Overview

Problem

Existing scroll compressors are limited in size due to the alignment of the orbiting scroll's center with the frame center, restricting the size of structural elements and reducing refrigerant suction pressure, thereby limiting performance.

Innovation Solution

The orbiting-base plate portion and boss portion are positioned eccentrically, allowing a larger non-motion range for the orbiting scroll and structural elements, enhancing the compressor's capacity and performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the center of the orbiting scroll is aligned with the center of the frame, then the structure is simple and stable, but the size of structural elements is restricted and refrigerant suction pressure is reduced

Engineering Contradiction:
Improvestructural stabilityVSAvoidrefrigerant suction pressure
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent applies asymmetry by positioning the center of the orbiting scroll (center line 54) at a different location than the center of the frame (center line 52). The orbiting scroll's center is offset toward the suction port side, creating an asymmetric configuration that enlarges the non-motion range area and allows larger structural elements, thereby increasing refrigerant suction pressure while maintaining structural stability through the controlled asymmetric design

Inventive Principle:
Principle #4Asymmetry

2Productivity

If the orbiting scroll size is increased, then compression capacity is improved, but the structural elements may overlap with suction ports

Engineering Contradiction:
Improvecompression capacityVSAvoidoverlap with suction ports
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

By asymmetrically positioning the orbiting scroll center relative to the frame center, the patent creates an enlarged non-motion range area that provides additional space. This allows the orbiting scroll to be sized larger for improved compression capacity while the asymmetric offset prevents overlap with suction ports by directing the motion range away from the suction port location

Inventive Principle:
Principle #4Asymmetry

3Productivity

If structural elements in the frame outer circumference are enlarged, then performance is improved, but they may block suction ports

Engineering Contradiction:
Improvecompressor performanceVSAvoidblockage of suction ports
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

The asymmetric positioning of the orbiting scroll center creates a non-motion range that is offset from the frame center toward the suction port side. This asymmetric configuration allows structural elements to be enlarged in the non-motion range area without blocking suction ports, as the orbiting scroll's motion range is directed away from the suction port location by the offset center position

Inventive Principle:
Principle #4Asymmetry

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 enlarges the orbiting scroll and structural elements, preventing overlap with suction ports and improving refrigerant supply, resulting in a high-performance scroll compressor.

Implementation Method 1

the orbiting-base plate portion and the boss portion are located such that a center in a motion range in which the orbiting-base plate portion is movable is eccentric from a center of the frame

Methodology Applied
Scientific EffectEccentric motion: Eccentric

Data Source

PatentEP4446589B1Scroll compressor
Publication Date: 2025.12.31 MITSUBISHI ELECTRIC CORP
  • EP4446589B1 patent drawingFigure 1
  • EP4446589B1 patent drawingFigure 2~3
  • EP4446589B1 patent drawingFigure 4~5

AI summary

A scroll compressor is provided with a compression mechanism unit that has a fixed scroll and an orbiting scroll and is configured to compress refrigerant, a rotation shaft that has an eccentric portion, a motor unit configured to drive the compression mechanism unit by use of the rotation shaft, a pressure vessel in which the compression mechanism unit and the motor unit are housed, and a frame that is fixed to the inside of the pressure vessel and supports the orbiting scroll in an axial direction in which the rotation shaft extends. The orbiting scroll has an orbiting-base plate portion, an orbiting scroll wrap provided in a first face of the orbiting-base plate portion that faces the fixed scroll, and a boss portion provided in a second face of the orbiting-base plate portion that is opposite to the first face and in which the eccentric portion is fitted with each other. The orbiting-base plate portion and the boss portion are located such that the position of the center of the orbiting-base plate portion differs from the position of the center of the boss portion when the orbiting-base plate portion and the boss portion are viewed in the axial direction.