Segmented Piston Rotor for Crankshaft Deflection in Rotary Compressors

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Solution Overview

Problem

In rotary compressors, the crankshaft can become bent and inclined during refrigerant compression, leading to partial contact with the rotor, increased friction loss, and reduced compressor performance and reliability.

Innovation Solution

The design includes a crankshaft with eccentric shaft portions and rotor separate bodies that adjust to follow the inclination, increasing the contact region and reducing friction loss, while also incorporating a second eccentric shaft portion with a larger radial length and a third shaft portion to minimize deflection and enhance rigidity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the crankshaft is used for refrigerant compression, then the compressor can compress the refrigerant, but the crankshaft becomes bent and inclined due to gas load, causing partial contact with the rotor and increasing friction loss

Engineering Contradiction:

Improverefrigerant compression capabilityVSAvoidfriction loss

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

The rotor is divided into multiple rotor separate bodies (first, second, third rotor separate bodies) that can independently move in the radial direction. This segmentation allows each rotor separate body to follow the inclination of the eccentric shaft portion, increasing the contact region and reducing friction loss while maintaining compression capability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The rotor separate bodies are designed to be movable relative to each other in the radial direction, enabling dynamic adjustment to follow the crankshaft's inclination. This dynamic adaptation reduces partial contact and friction loss during operation.

Inventive Principle:

Principle #15Dynamics

2Productivity

If the crankshaft is used for refrigerant compression, then the compressor can compress the refrigerant, but the crankshaft becomes bent and inclined due to gas load, reducing compressor reliability

Engineering Contradiction:

Improverefrigerant compression capabilityVSAvoidcompressor reliability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The rotor is segmented into multiple independently movable rotor separate bodies that can adapt to crankshaft deflection, preventing abnormal stress concentration and improving reliability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The radial position of the rotor separate bodies is changed dynamically to follow the crankshaft's inclination, reducing abnormal stress and improving operational reliability.

Inventive Principle:

Principle #35Parameter changes

3Strength

If the second shaft portion has a small radial length to reduce deflection, then the rigidity increases, but the overall shaft length is reduced

Engineering Contradiction:

Improveshaft rigidityVSAvoidshaft length

Core Design Contradiction:

StrengthVSLength of moving object

Solution Approach 1:

The rotor segmentation allows for a more optimized shaft design where the second shaft portion can have a smaller radial length without compromising overall performance, as the segmented rotor compensates for the reduced support length.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentEP3557067B1Piston rotor, crankshaft, rotary compressor, and assembling method of crankshaft

Publication Date: 2021.12.29 MITSUBISHI HEAVY IND THERMAL SYST

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AI summary

A first piston rotor (13A) is a piston rotor of the crankshaft (16) which is configured to rotate around an axis O in a rotary compressor and has a plurality of rotor separate bodies (131A) respectively formed in an annular shape centered on a center line. The plurality of rotor separate bodies (131A) are movable relative to each other in a state in which the plurality of rotor separate bodies (131A) are in contact with each other in a direction in which the center line extends.