Oil-free Screw Compressor Shaft Seal Integration

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Solution Overview

Problem

The oil-free screw compressor faces challenges with poor assemblability and increased leakage of compressed gas due to the separation of shaft seal devices, which can lead to gaps and inefficiencies in sealing.

Innovation Solution

The integration of the packing case and oil seal of the shaft seal device through interference fit forms a gas seal accommodation space, reducing the gap and enhancing assemblability while minimizing gas leakage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the shaft seal device is separated into multiple components for assembly, then the ease of assembly is improved, but the manufacturing precision deteriorates due to gaps between components

Engineering Contradiction:
ImproveassemblabilityVSAvoidsealing gap
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent merges the packing case and oil seal into a single integrated component. The packing case includes an integrated oil seal portion formed directly on its inner peripheral surface, eliminating the need for separate assembly of multiple seal components. This integration ensures continuous sealing contact without gaps that would occur with separate components, while still allowing for straightforward assembly as a single unit.

Inventive Principle:
Principle #5Merging (Combining)

2Ease of operation

If the shaft seal device components are assembled separately, then the ease of operation is improved, but the reliability deteriorates due to potential leakage paths

Engineering Contradiction:
ImproveassemblabilityVSAvoidsealing performance
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The oil seal and packing case are merged into a single integrated structure where the oil seal portion is formed directly on the inner peripheral surface of the packing case. This integration eliminates potential leakage paths at the interface between separate components, ensuring continuous sealing contact with the rotor shaft while maintaining ease of assembly as a single unit.

Inventive Principle:
Principle #5Merging (Combining)

3Manufacturing precision

If interference fit is used to integrate components, then the manufacturing precision is improved by reducing gaps, but the device complexity increases

Engineering Contradiction:
Improvesealing gapVSAvoidassembly complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent eliminates the need for interference fit between separate packing case and oil seal components by integrating the oil seal portion directly onto the packing case. This single-component design achieves perfect sealing contact without requiring complex interference fit procedures, pressurized assembly, or specialized tooling, thereby reducing assembly complexity while maintaining manufacturing precision.

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 configuration improves the assemblability of the shaft seal device and significantly reduces the leakage of compressed gas by creating a tight seal, even when the rotor shaft warps, maintaining effective sealing performance.

Implementation Method 1

the packing case and the oil seal of the shaft seal device are fitted and fixed by interference fit

Methodology Applied
Scientific EffectInterference fit:

Data Source

PatentEP3118457B1Oil-free screw compressor
Publication Date: 2019.02.20 KOBE STEEL LTD
  • EP3118457B1 patent drawingFigure 1
  • EP3118457B1 patent drawingFigure 2
  • EP3118457B1 patent drawingFigure 3

AI summary

Provided is an oil-free screw compressor with good assemblability of a shaft seal device reduces leakage of a compressed gas. An oil-free screw compressor (1) accommodates male and female screw rotors (16) in a rotor chamber (15) of a casing (12), supports each screw rotor by a bearing (22) through a rotor shaft (21), and has shaft seal devices (30, 40) in a shaft seal space (10). The shaft seal devices include an oil seal (31) on the side of the bearing, a packing case (41) on the side of the rotor chamber, and a gas seal (42). An end (44) of the packing case on the side of the bearing and an end (33) of the oil seal on the side of the rotor chamber are fitted and fixed by interference fit to form a gas seal accommodation space (48), the gas seal accommodation space accommodating the seal ring.