Variable Mesh Clearance Scroll Compressor Wall Design

Solution Overview

Problem

The stepped scroll compressor experiences significant fluid leakage and stress concentration at the base of the step portion, leading to decreased strength and potential damage due to increased bending stress.

Innovation Solution

A scroll fluid machine design featuring a continuously inclined portion on the scroll walls, where the inter-facing surface distance between end plates decreases from the outer to the inner peripheral sides, with larger mesh clearance on the outer side to alleviate bending stress and reduce fluid leakage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a continuously inclined portion is provided on the scroll walls to eliminate step portions, then fluid leakage is reduced and stress concentration is alleviated, but bending stress increases at the base of the wall due to the large moment applied during tooth surface contact

Engineering Contradiction:

Improvefluid leakage reductionVSAvoidbending stress at wall base

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent applies different mesh clearances at different locations of the scroll walls. Specifically, the mesh clearance is set to be larger at the outer peripheral side and smaller at the inner peripheral side of the inclined portion. This local differentiation allows the structure to accommodate the varying stress conditions - the larger clearance at the outer side reduces bending stress where the wall height is greater and moment is larger, while the smaller clearance at the inner side maintains compression performance where the wall height is smaller

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the mesh clearance parameter along the spiral direction of the scroll walls. By making the mesh clearance variable (larger at outer peripheral side, smaller at inner peripheral side) rather than uniform, the design optimizes both structural strength and compression performance. This parameter change allows the system to handle the varying moments and stresses that occur at different radial positions of the inclined portion

Inventive Principle:

Principle #35Parameter changes

2Strength

If the mesh clearance on the outer peripheral side is increased to reduce bending stress, then the moment applied to the wall base is alleviated, but fluid leakage may increase

Engineering Contradiction:

Improvebending stress reductionVSAvoidfluid leakage control

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The patent applies different mesh clearances at different locations of the scroll walls. Specifically, the mesh clearance is set to be larger at the outer peripheral side and smaller at the inner peripheral side of the inclined portion. This local differentiation allows the structure to accommodate the varying stress conditions - the larger clearance at the outer side reduces bending stress where the wall height is greater and moment is larger, while the smaller clearance at the inner side maintains compression performance where the wall height is smaller

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the mesh clearance parameter along the spiral direction of the scroll walls. By making the mesh clearance variable (larger at outer peripheral side, smaller at inner peripheral side) rather than uniform, the design optimizes both structural strength and compression performance. This parameter change allows the system to handle the varying moments and stresses that occur at different radial positions of the inclined portion

Inventive Principle:

Principle #35Parameter changes

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 design effectively reduces bending stress on the base of the scroll walls while maintaining or improving compression performance by managing the moment applied during tooth surface contact, minimizing fluid leakage, and ensuring accurate processing without excessive tooth surface contact.

Implementation Method 1

a fixed scroll member and an orbiting scroll member each having a spiral wall provided on an end plate mesh with each other so as to perform a revolution orbiting movement and a fluid is compressed or expanded

Methodology Applied

Scientific EffectMechanical compression: Compression

Implementation Method 2

an inclined portion in which an inter-facing surface distance between the first end plate and the second end plate facing each other continuously decreases from outer peripheral sides of the first wall and the second wall toward inner peripheral sides thereof

Methodology Applied

Scientific EffectThree-dimensional compression: Compression

Data Source

PatentUS11078906B2Scroll fluid machine having a different mesh clearance between the fixed and orbiting scroll wraps

Publication Date: 2021.08.03 MITSUBISHI HEAVY IND THERMAL SYST

AI summary

A scroll fluid machine that attenuates the bending stress applied to the base of a wall body having an inclined section. The scroll fluid machine is provided with a wall body inclined section in which the distance between the facing surfaces of an end plate of a fixed scroll and an end plate of a rotating scroll that face each other continuously decreases from the outer circumferential side toward the inner circumferential side. A mesh clearance that is a gap between wall bodies formed when the wall bodies mesh with each other is larger on the outer circumferential side of the inclined section than on the inner circumferential side of the inclined section. The mesh clearance is made larger by drawing the wall surface of a wall body further back toward the central side of the wall body in the thickness direction than the original wall surface profile thereof.