Integrated Screw Compressor Motor and Compression Housing

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Solution Overview

Problem

Existing screw compressors face inefficiencies due to power losses from high-speed rotor shaft seals, wear, leaks, and complex separate lubrication and cooling systems, which also hinder heat recovery.

Innovation Solution

A screw compressor design where the compression housing and motor housing form a single unit, eliminating the need for a shaft seal and using a shared coolant/lubricant for both the drive motor and compressor rotors, enhancing energy efficiency and simplifying the system.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a contact seal is used to seal the rotor shaft in known screw compressors, then the compression chamber can be sealed from the ambient pressure, but enormous power losses occur during operation and the seal is subject to wear and leaks

Engineering Contradiction:
Improvesealing reliabilityVSAvoidpower loss
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The patent merges the motor chamber and compression chamber into a single integrated housing, allowing the rotor shaft to be sealed internally without requiring external contact seals. The motor shaft couples directly to the rotor shaft through a sealed interface within the compression chamber, eliminating the need for separate sealing mechanisms and reducing power losses while maintaining sealing reliability.

Inventive Principle:
Principle #5Merging (Combining)

2Reliability

If separate lubrication and cooling systems are used for the drive motor and compressor rotors, then each component can be adequately lubricated and cooled, but the systems become complicated and expensive with multiple lubricants and coolants

Engineering Contradiction:
Improvecomponent protectionVSAvoidsystem complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent implements a universal lubrication and cooling system where a single lubricant serves multiple functions: it cools the motor, lubricates the rotor shaft bearings, and provides sealing at the shaft interface. This multi-functional approach eliminates the need for separate lubrication and cooling circuits, reducing system complexity while ensuring adequate protection of all components.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Temperature

If separate cooling systems are used for the drive motor and compressor rotors, then each component can be cooled independently, but the possibilities for recovering lost heat are not fully utilised

Engineering Contradiction:
Improvecomponent coolingVSAvoidheat recovery potential
Core Design Contradiction:
TemperatureVSLoss of energy

Solution Approach 1:

The patent combines the cooling functions into a single circuit that captures heat from both the motor and compressor rotors through the common lubricant. This merged cooling system allows for comprehensive heat recovery by utilizing the thermal energy from both heat sources, converting what would be wasted heat into usable energy for water heating or other thermal applications.

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 reduces energy losses, minimizes wear and leaks, simplifies lubrication and cooling, and improves heat recovery by using a single fluid for both components, leading to a more robust, efficient, and cost-effective compressor.

Implementation Method 1

a cooling circuit for cooling the drive motor and the compression chamber in which a coolant flows along a cooling path from the drive motor to the compression chamber

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

the coolant flows along a cooling path from the drive motor to the compression chamber

Methodology Applied
Scientific EffectConvection: Convection

Implementation Method 3

a lubrication circuit for lubricating the bearings with a lubricant that flows along a lubrication path through the bearings

Methodology Applied
Scientific EffectLubrication: Lubrication

Implementation Method 4

In a development of the invention, the same fluid is used as coolant and lubricant

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentEP3228867B1Screw compressor
Publication Date: 2019.12.11 ATLAS COPCO AIRPOWER NV
  • EP3228867B1 patent drawingFigure 1
  • EP3228867B1 patent drawingFigure 2

AI summary

Screw compressor (1) with a compression chamber (2) that is formed by a compression housing (3), in which a pair of meshed helical compressor rotors (4,5) in the form of a screw are rotatably mounted and with a drive motor (14) that is provided with a motor chamber (16) formed by a motor housing (15), in which a motor shaft (17) is rotatably mounted, and this motor shaft (17) drives at least one of the aforementioned two compressor rotors (4,5), whereby the compression housing (3) and the motor housing (15) are connected directly together to form a compressor housing (28), whereby the motor chamber (16) and the compression chamber (2) are not sealed off from one another and whereby the rotor shafts (7,8) of the compressor rotors (4,5), as well as the motor shaft (17), extend along axial directions (AA',BB',CC') that are oblique or transverse to the horizontal plane.