Centrifugal Compressor Clearance Seal for Diaphragm Leakage Control

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Solution Overview

Problem

In centrifugal compressors with a vertically divided casing, fluid leakage occurs between the inner peripheral surface of the casing and the outer peripheral surface of the diaphragm due to the connection of suction and discharge ports via the clearance, leading to pressure differences.

Innovation Solution

A compressor design that includes a communication clearance seal portion and a restricting portion to seal the communication clearance between the diaphragm and casing, using a clearance seal attachment groove and a fitting recessed/projection structure to restrict the diaphragm's position, thereby reducing leakage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a rotary valve is used in a screw compressor, then the compressor can achieve continuous compression and improved productivity, but the complexity of the device increases due to additional moving parts and sealing requirements

Engineering Contradiction:
Improvecontinuous compression capabilityVSAvoidcomplexity of moving parts and sealing
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent combines the rotary valve function with the housing structure by forming the valve body as an integral part of the housing through casting or machining. This merging eliminates the need for separate valve components and their associated sealing interfaces, thereby reducing device complexity while maintaining the continuous compression capability provided by the rotary valve mechanism.

Inventive Principle:
Principle #5Merging (Combining)

2Manufacturing precision

If conventional manufacturing methods are used for the housing and rotary valve, then manufacturing precision can be achieved, but the manufacturing time and productivity are reduced

Engineering Contradiction:
Improveprecision of housing and valveVSAvoidmanufacturing time
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The patent integrates the housing and rotary valve into a single monoblock component manufactured through conventional casting or machining processes. This eliminates the need for separate manufacturing of the housing and valve, followed by assembly operations. The single-piece manufacturing approach reduces total manufacturing time and assembly steps while maintaining the manufacturing precision required for the compression chamber geometry and sealing surfaces.

Inventive Principle:
Principle #5Merging (Combining)

3Ease of manufacture

If the rotary valve and housing are manufactured separately and then assembled, then manufacturing flexibility is improved, but assembly time and productivity are reduced

Engineering Contradiction:
Improvemanufacturing flexibilityVSAvoidassembly time
Core Design Contradiction:
Ease of manufactureVSProductivity

Solution Approach 1:

The patent produces the housing and rotary valve as a single integrated component through conventional manufacturing processes. This eliminates all assembly operations between these two parts, thereby eliminating assembly time and potential assembly errors. The design maintains manufacturing flexibility by allowing the integrated component to be produced using standard casting or machining methods suitable for the required production volume and precision levels.

Inventive Principle:
Principle #5Merging (Combining)

Data Source

PatentEP3770441B1Compressor and method for manufacturing compressor
Publication Date: 2026.05.06 MITSUBISHI HEAVY INDUSTIES COMPRESSOR CORP
  • EP3770441B1 patent drawingFigure 1
  • EP3770441B1 patent drawingFigure 2~3
  • EP3770441B1 patent drawingFigure 4~5

AI summary

A compressor 1 includes a casing 2 having an upper half casing 21 and a lower half casing 22 and a tubular shape with both ends open, a bundle 10 including annular heads 14 respectively fixed on both sides in an axial direction with respect to a plurality of diaphragms 13 and closing openings of the casing 2, a communication clearance seal portion 16 sealing a communication clearance C extending in the axial direction between the outer peripheral surface of the diaphragm 13 and the inner peripheral surface of the casing 2 such that a suction opening 236 and a discharge opening 237 communicate with each other, and a regulating portion 18 regulating the position of the head 14 in the axial direction with respect to the casing 2.