Co-rotating Scroll Compressor Preload Design

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Solution Overview

Problem

Co-rotating scroll compressors experience deformation and thermal stress due to centrifugal forces and temperature changes, leading to inefficiencies and potential leakage during high-speed operation.

Innovation Solution

The implementation of a co-rotating scroll compressor design that applies preloads to bearings to mitigate deformation caused by centrifugal forces and allows for thermal expansion, reducing stress and leakage by adjusting the distance between shaft parts supported by bearings.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the scroll part rotates at high speed, then the compression efficiency is improved, but deformation caused by centrifugal force increases

Engineering Contradiction:
Improvecompression efficiencyVSAvoidscroll deformation
Core Design Contradiction:
ProductivityVSShape

Solution Approach 1:

The patent applies a preload mechanism to the shaft part that generates a counteracting force against the centrifugal force. The preload member (such as a spring or adjustable preload device) exerts a force in the opposite direction to the centrifugal deformation, thereby compensating for the shape change and maintaining scroll integrity during high-speed rotation.

Inventive Principle:
Principle #8Anti-weight (Counterweight)

Solution Approach 2:

The preload is applied in advance to the shaft part before high-speed rotation begins. This preliminary action creates an initial stress state in the scroll that counteracts the expected centrifugal deformation during operation, preventing excessive deformation from occurring in the first place.

Inventive Principle:
Principle #9Preliminary anti-action

2Productivity

If the operating temperature rises, then the compression capacity is improved, but thermal stress in the scroll part increases

Engineering Contradiction:
Improvecompression capacityVSAvoidthermal stress
Core Design Contradiction:
ProductivityVSStress or pressure

Solution Approach 1:

The patent introduces a preload parameter that can be adjusted to compensate for thermal expansion. As temperature rises and the scroll expands, the preload mechanism maintains appropriate contact pressure and stress distribution, preventing excessive thermal stress by allowing controlled parameter adjustment in response to temperature changes.

Inventive Principle:
Principle #35Parameter changes

3Shape

If additional preload members are added to the bearing assembly, then deformation is alleviated, but device complexity increases

Engineering Contradiction:
Improvescroll deformationVSAvoidbearing assembly complexity
Core Design Contradiction:
ShapeVSDevice complexity

Solution Approach 1:

The patent integrates the preload function directly into the existing bearing assembly structure. The preload member is combined with the bearing support system, sharing common mounting locations and structural elements. This merging approach allows the preload function to be added without proportionally increasing overall device complexity, as the preload mechanism utilizes existing structural resources.

Inventive Principle:
Principle #5Merging (Combining)

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 alleviates deformation and thermal stress, enhancing the compressor's operational efficiency and reducing fluid leakage, while also simplifying the assembly process by eliminating the need for additional preload members.

Implementation Method 1

deformation is generated by a centrifugal force in a scroll part. In particular, in the case of high-speed rotation, the deformation caused by the centrifugal force can not be ignored.

Methodology Applied
Scientific EffectCentrifugal force: Centrifugal Force

Implementation Method 2

when a temperature rises during the operation of the co-rotating scroll compressor, thermal stress may be generated in the scroll part

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentEP3489514B1Bidirectional-rotation-type scroll compressor
Publication Date: 2020.02.12 MITSUBISHI HEAVY IND LTD
  • EP3489514B1 patent drawingFigure 1
  • EP3489514B1 patent drawingFigure 2
  • EP3489514B1 patent drawingFigure 3

AI summary

Provided is a co-rotating scroll compressor which can alleviate the deformation caused by a centrifugal force generated in a scroll part. The present invention includes: a first driving side bearing (11) and a second driving side bearing (14) which rotatably support a driving side scroll member (70) on shaft parts at one end side and the other end side in the axial direction, wherein a preload applied to a first driving side shaft part (7c) so that an axial clearance in the second driving side bearing (14) direction is eliminated in the first driving side bearing (11), and a preload is applied to a second driving side shaft part (72c) so that an axial clearance in the first driving side bearing (11) direction is eliminated in the second driving side bearing (14).