Scroll Compressor Cooling Duct Geometry for Vortex-Free Airflow

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Solution Overview

Problem

In scroll-type fluid machines, temperature rises due to compression heat and bearing heat lead to efficiency decreases and reliability issues, and existing cooling air passage designs often suffer from inefficient airflow and increased costs due to complex mold requirements.

Innovation Solution

A scroll-type fluid machine with a cooling air passage featuring a bent portion where the outer peripheral wall intersects a plane perpendicular to the drive shaft at an obtuse angle, preventing vortex formation and allowing efficient airflow without increasing production costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the cooling air passage includes a bent portion to change flow direction from radial to axial, then cooling function is provided, but a vortex is generated on the inner peripheral side preventing efficient airflow

Engineering Contradiction:
Improvecooling functionVSAvoidairflow efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The bent portion of the cooling air passage is designed with a curved surface instead of a sharp angle to reduce vortex generation. The curvature radius is optimized to balance between maintaining compact structure and ensuring smooth airflow transition, thereby improving airflow efficiency while preserving the cooling function.

Inventive Principle:
Principle #14Spheroidality (Curvature)

2Productivity

If the radius of the bent portion is set large to allow cooling air to flow efficiently, then airflow efficiency is improved, but the mold becomes large in height direction increasing cost and reducing productivity

Engineering Contradiction:
Improveairflow efficiencyVSAvoidmold cost
Core Design Contradiction:
ProductivityVSEase of manufacture

Solution Approach 1:

Instead of increasing the radius in the radial direction which would increase mold height, the invention optimizes the bent portion geometry by adjusting the curvature radius and the angle of the bent portion in the axial direction. This dimensional optimization allows efficient airflow while maintaining a compact mold height suitable for cost-effective production.

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

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 enhances airflow efficiency, reduces noise and cooling air loss, and maintains productivity by preventing vortices and allowing for simpler, cost-effective component division.

Implementation Method 1

since the cooling air flows on an outer peripheral side of the bent portion because of the centrifugal force, a vortex is generated on an inner peripheral side thereof

Methodology Applied
Scientific EffectCentrifugal force: Centrifugal Force

Data Source

PatentEP3763942B1Scroll-type fluid machine
Publication Date: 2024.06.26 HITACHI IND EQUIP SYST CO LTD
  • EP3763942B1 patent drawingFigure 1~2
  • EP3763942B1 patent drawingFigure 3~4
  • EP3763942B1 patent drawingFigure 5~6

AI summary

Provided is a scroll-type fluid machine that has an improved reliability without a reduction in productivity by adopting a simple shape of a cooling air passage to allow a cooling air to flow efficiently. Accordingly, a scroll-type fluid machine includes a fixed scroll that is provided with a lap portion having a spiral shape; an orbiting scroll that is provided with a lap portion having a spiral shape which forms a compression chamber between the lap portion of the fixed scroll and the lap portion; a drive shaft that is connected to the orbiting scroll and rotates to cause the orbiting scroll to orbit; a cooling fan that is provided on a side of the drive shaft, the side being opposite to the orbiting scroll, to generate a cooling air; and a cooling air duct through which the cooling air generated by the cooling fan flows to the fixed scroll and the orbiting scroll. In a bent portion where a direction of the cooling air duct is changed from a direction perpendicular to the drive shaft to a direction of the drive shaft, a part of an outer peripheral wall which is distant from the drive shaft is formed by a plane which intersects a plane perpendicular to the drive shaft at an obtuse angle.