Scroll Fluid Machine Chamfered Tooth Tip Corners

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Stepped scroll compressors experience significant fluid leakage and strength reduction due to concentrated stress at the step portion, with challenges in processing accuracy leading to potential contact between tooth tip and tooth bottom corners, affecting performance.

Innovation Solution

A scroll fluid machine with inclined portions where the inter-facing surface distance between end plates decreases from the outer to the inner peripheral side, featuring chamfered tooth tip corners to prevent contact and a method for processing that includes separate passes for peripheral wall and tooth bottom surfaces to ensure accurate processing of the inclined portion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If step portions are provided on spiral walls to increase compressor capacity, then the amount of displacement increases, but fluid leakage in the step portion increases and stress concentrates reducing strength

Engineering Contradiction:

Improvecompressor capacityVSAvoidstrength

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent replaces the stepped structure with a continuously curved inclined surface on the spiral wall. This curvature eliminates abrupt transitions and stress concentration points while maintaining the three-dimensional compression capability, thus improving strength without sacrificing compressor capacity

Inventive Principle:

Principle #14Spheroidality (Curvature)

2Reliability

If a continuously inclined portion is provided instead of step portion, then fluid leakage is reduced, but processing difficulty increases and accuracy decreases

Engineering Contradiction:

Improvefluid leakage preventionVSAvoidtooth bottom corner accuracy

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent applies preliminary chamfering to the tooth tip corners before the main machining process. This pre-preparation creates a rounded transition that prevents contact between opposing corners during operation, compensating for potential machining inaccuracies and ensuring reliable performance even when processing precision varies

Inventive Principle:

Principle #10Preliminary action

3Ease of manufacture

If tooth bottom corner processing accuracy decreases, then the tooth tip corner contacts the tooth bottom corner, but performance decreases

Engineering Contradiction:

Improveprocessing easeVSAvoidperformance

Core Design Contradiction:

Ease of manufactureVSProductivity

Solution Approach 1:

The chamfered portion acts as a cushioning feature that prevents direct contact between the tooth tip corner and tooth bottom corner. By preparing this protective geometry in advance, the patent ensures that even if machining accuracy is not perfect, the corners will not contact and performance will not deteriorate

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Data Source

PatentEP3428451B1Scroll fluid machine, and method for processing scroll member

Publication Date: 2022.06.08 MITSUBISHI HEAVY IND THERMAL SYST

Figure 1A~1B
Figure 2
Figure 3

AI summary

Provided is a scroll fluid machine which is capable of inhibiting contact between tooth tip corners and tooth bottom corners. The present invention is provided with: a wall inclined portion (3b1) of which a facing surface has a distance to an end plate which continuously decreases from the outer circumferential side to the inner circumferential side; and an end plate inclined portion (5a1). Chamfered portions (8a) are provided to tooth tip corners (8) of a tooth tip of a wall (3b) which face tooth bottom corners (9) of bases of mating walls (5b). The chamfered portions (8a) have a shape which avoids contact with step parts (9a) which are formed at the tooth bottom, and which are adjacent to the tooth bottom corners (9).