Screw Compressor Symmetric Grooves Thrust Balance

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Solution Overview

Problem

Conventional screw compressors face issues with leakage on the high-pressure side due to labyrinth seals and unbalanced thrust loads, which reduce performance, especially as capacity increases, leading to efficiency losses and difficulty in improving large capacity compressor performance.

Innovation Solution

A single screw compressor design featuring a rotatable screw rotor with helical grooves and radially disposed teeth on gate rotors, including a first and second screw groove arranged in a rotational axis direction for symmetry, along with an intermediate bearing and twin bearings, to reduce leakage and balance thrust loads, allowing for a compact, high-efficiency, large capacity compressor.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single screw groove compresses fluid from one end side to the other end side, then the compression process is simple, but leakage occurs on the high pressure side and thrust load becomes unbalanced

Engineering Contradiction:
Improvescrew groove structureVSAvoidleakage reduction
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The single screw groove is segmented into a first screw groove and a second screw groove that are planarly symmetric with respect to the rotational axis. This segmentation allows the compression medium to be compressed in opposite directions, balancing the thrust load and reducing high-pressure side leakage while maintaining structural simplicity.

Inventive Principle:
Principle #1Segmentation

2Productivity

If capacity is increased to improve compressor efficiency, then efficiency improves, but pressure loss and leakage increase reducing efficiency

Engineering Contradiction:
Improvecompressor capacityVSAvoidpressure loss and leakage
Core Design Contradiction:
ProductivityVSLoss of energy

Solution Approach 1:

The planarly symmetric first and second screw grooves create counterbalancing thrust loads that offset each other. This counterweight effect eliminates the need for high-pressure seals at the ends, reducing leakage losses and allowing capacity increase without proportional increases in energy loss.

Inventive Principle:
Principle #8Anti-weight (Counterweight)

3Ease of operation

If thrust load is continuously applied in one direction, then the compression process is straightforward, but the structure cannot completely eliminate thrust load

Engineering Contradiction:
Improvecompression processVSAvoidthrust load balance
Core Design Contradiction:
Ease of operationVSForce

Solution Approach 1:

While maintaining overall symmetry for balance, the screw grooves are positioned asymmetrically relative to the endpoint seals, creating pressure distribution that balances thrust load. The planar symmetry about the rotational axis ensures equal and opposite thrust components while the groove orientation optimizes compression efficiency.

Inventive Principle:
Principle #4Asymmetry

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

The design effectively reduces high-pressure side leakage and balances thrust loads, enabling the creation of a compact, high-efficiency, large capacity compressor with reduced parts and manufacturing costs, while minimizing pressure losses and facilitating easier motor cooling.

Implementation Method 1

a first screw groove, which compresses a fluid from one end side of the screw rotor to an other end side; and a second screw groove, which compresses the fluid from the other end side of the screw rotor to the one end side

Methodology Applied
Scientific EffectCompression: Compression

Data Source

PatentEP2236831B1Screw compressor
Publication Date: 2018.09.19 DAIKIN INDUSTRIES LTD
  • EP2236831B1 patent drawingFigure 1
  • EP2236831B1 patent drawingFigure 2
  • EP2236831B1 patent drawingFigure 3~4

AI summary

The present invention provides a screw compressor that can reduce leakage on the high pressure side and reduce the thrust load. A screw compressor (1) comprises a screw rotor (2, 52) and a plurality of gate rotors (5a, 5b, 5c, 5d). The screw rotor (2, 52) has helical grooves (11a, 11b) in its outer circumferential surface, and is rotatable. In the gate rotors (5a, 5b, 5c, 5d), a plurality of teeth (12) that meshes with the grooves (11a, 11b) of the screw rotor (2, 52) is radially disposed. The helical grooves (11a, 11b) comprise: a first screw groove (11a), which compresses a fluid from one end side of the screw rotor (2, 52) to an other end side of the screw rotor (2, 52); and a second screw groove (11b), which compresses the fluid from the other end side of the screw rotor (2, 52) to the one end side of the screw rotor (2, 52).