Rotary Machine Shaft Vibration Control via Additional Masses

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Solution Overview

Problem

Existing rotary machines face challenges in effectively suppressing vibrations of the rotating shaft, particularly when the positional relationship or size of the impeller and radial bearing is not optimal, leading to insufficient vibration control.

Innovation Solution

The implementation of a rotary machine design that includes a rotating shaft supported by a pair of radial bearings and a thrust bearing, with additional masses fixed to the shaft at positions separated from both the radial bearings and impellers, which applies a load to the entire circumference of the shaft to relocate amplitude increase regions and enhance support from the radial bearings.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If only radial bearings are used to support the rotating shaft, then the structure is simple, but the vibration suppression is insufficient when the positional relationship or size of the impeller and radial bearing is not optimal

Engineering Contradiction:

Improvestructure simplicityVSAvoidvibration suppression effectiveness

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent introduces additional masses as intermediary elements fixed to the rotating shaft between the impeller and radial bearing. These additional masses act as mediators that generate centrifugal forces to move the amplitude increase region toward the radial bearing, thereby improving vibration suppression without fundamentally changing the bearing support structure.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the mass distribution parameter by adding additional masses at specific positions on the rotating shaft. This parameter change alters the dynamic characteristics of the system, moving the amplitude increase region and improving vibration suppression effectiveness while maintaining structural simplicity.

Inventive Principle:

Principle #35Parameter changes

2Ease of operation

If the impeller is positioned at the end portion of the rotating shaft beyond the radial bearings, then the impeller can be properly positioned for operation, but the impeller is likely to vibrate excessively

Engineering Contradiction:

Improveimpeller positioningVSAvoidimpeller vibration control

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The additional masses serve as intermediary elements that generate centrifugal forces to influence the vibration characteristics of the impeller. By positioning these masses between the impeller and radial bearing, the amplitude increase region is moved toward the radial bearing, thereby reducing impeller vibration while maintaining its operational positioning.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The additional masses function as counterweights that balance the vibratory forces generated by the impeller. By strategically positioning these counterweights, the patent creates opposing centrifugal forces that reduce the net vibration of the impeller while allowing it to remain at its operational position.

Inventive Principle:

Principle #8Anti-weight (Counterweight)

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 effectively suppresses vibrations of the rotating shaft by increasing the radial load on the radial bearings, ensuring effective vibration control regardless of the impeller and radial bearing positions, and utilizes centrifugal forces to firmly fix additional masses to the shaft, thereby stabilizing the machine.

Implementation Method 1

additional masses fixed to the rotating shaft at positions separated from both the radial bearings and the impellers in the center axis direction, and applying a load to an entire circumference of the rotating shaft so as to move positions of amplitude increase regions where an amplitude in a radial direction of the rotating shaft starts to increase

Methodology Applied

Scientific EffectCentrifugal force: Centrifugal Force

Implementation Method 2

a pair of radial bearings for rotatably supporting the rotating shaft around the center axis

Methodology Applied

Scientific EffectRadial bearing support: Ball Bearing

Implementation Method 3

a thrust bearing for restraining movement of the rotating shaft in a center axis direction

Methodology Applied

Scientific EffectThrust bearing restraint: Ball Bearing

Data Source

PatentUS11143206B2Rotary machine

Publication Date: 2021.10.12 MITSUBISHI HEAVY INDUSTIES COMPRESSOR CORP

AI summary

A rotary machine includes: a pair of radial bearings for rotatably supporting a rotating shaft around a center axis; impellers fixed to the rotating shaft at positions separated from the radial bearings in a center axis direction; and additional masses fixed to the rotating shaft at positions separated from both the radial bearings and the impellers in the center axis direction, and applying a load to an entire circumference of the rotating shaft so as to move positions of amplitude increase regions where an amplitude in a radial direction of the rotating shaft starts to increase.