Screw Compressor Bearing Layout for High-Speed Load Capacity

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Solution Overview

Problem

Existing screw compressor bearings face challenges in achieving high radial load-bearing capacity and asymmetric axial load-bearing capacity, especially at high rotational speeds, due to limitations in lubrication and cooling.

Innovation Solution

A configuration of bearings comprising a cylinder bearing and a ball bearing, where the cylinder bearing provides high radial load-bearing capacity and the ball bearing absorbs axial forces asymmetrically, with no collars or 'edges' next to the raceways for improved lubrication and cooling, and a nozzle directing fluid jets into the bearings for enhanced lubrication.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If bearings are made as large as possible with the largest possible rolling elements to maximize load-bearing capacity, then radial and axial load-bearing capacity is improved, but the ability to operate at very high rotational speeds deteriorates due to lubrication and cooling difficulties

Engineering Contradiction:
Improveload-bearing capacityVSAvoidrotational speed
Core Design Contradiction:
StrengthVSSpeed

Solution Approach 1:

The bearing is divided into two distinct types: a cylinder bearing for radial load and a ball bearing for axial load. This segmentation allows each bearing type to be optimized for its specific function while operating at high speeds, resolving the contradiction between load-bearing capacity and rotational speed capability

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different bearing types are used at different locations along the shaft to provide locally optimized load-bearing characteristics. The cylinder bearing provides high radial load capacity where needed, while the ball bearing provides axial load capacity, allowing the system to achieve high speeds without compromising overall load-bearing performance

Inventive Principle:
Principle #3Local quality

2Device complexity

If a single bearing is used to support both radial and axial loads, then device complexity is reduced, but the load-bearing capacity in both directions deteriorates compared to specialized bearings

Engineering Contradiction:
Improvebearing configuration complexityVSAvoidload-bearing capacity
Core Design Contradiction:
Device complexityVSStrength

Solution Approach 1:

The combination of cylinder and ball bearings creates a multi-functional bearing system that handles both radial and axial loads simultaneously. Each bearing type contributes its specialized load-bearing capability, achieving universal load support without requiring an overly complex single-bearing solution

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

3Stability of the object's composition

If collars or edges are added to the inner ring next to the raceway to provide structural support, then bearing stability is improved, but lubrication and cooling effectiveness deteriorates due to blocked fluid access

Engineering Contradiction:
Improvebearing structural stabilityVSAvoidlubrication and cooling effectiveness
Core Design Contradiction:
Stability of the object's compositionVSReliability

Solution Approach 1:

The collars or edges that typically block lubrication access are removed from the inner ring next to the raceway. This extraction of the obstructive feature allows direct fluid access to the raceway while structural stability is maintained through the bearing's overall design and the presence of collars on the outer ring

Inventive Principle:
Principle #2Taking out (Extraction)

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 enables optimal load-bearing capacity and high-speed operation by ensuring effective lubrication and cooling, reducing the risk of overheating and increasing the service life of the bearings.

Implementation Method 1

a nozzle is arranged between the cylinder bearing and the ball bearing, wherein the nozzle is suited for directing jets of fluid into the cylinder bearing and/or the ball bearing

Methodology Applied
Scientific EffectFluid jet lubrication: Jet

Implementation Method 2

the oil is intended to provide lubrication and cooling

Methodology Applied
Scientific EffectLubrication: Lubrication

Implementation Method 3

the oil is intended to provide lubrication and cooling

Methodology Applied
Scientific EffectCooling: Cooling

Data Source

PatentEP3775559B1Screw compressor element and machine
Publication Date: 2025.05.07 ATLAS COPCO AIRPOWER NV
  • EP3775559B1 patent drawingFigure 1~2
  • EP3775559B1 patent drawingFigure 3

AI summary

Screw compressor element provided with a housing wherein a rotor is rotatably arranged by way of two bearings, respectively being a cylinder bearing (3) and a ball bearing (4), each provided with an inner ring (5, 6) and an outer ring (7, 8), separated by respectively cylindrical, or ball-shaped rolling elements (9, 10) that contact the inner ring (5, 6) and the outer ring (7, 8) at the location of a raceway (11a, 11b, 12a, 12b), characte rised in that,next to the respective raceway (11a, 12a), the inner rings (5, 6) of the aforementioned bearings (3, 4) have a smaller outer diameter (B) than the respective raceway (11a, 12a) on the side facing the other bearing (3, 4) and in that next; to the respective raceway (11a, 12a), the inner rings (5, 6) of the bearings have a greater outer diameter (C, D) than the respective raceway (11a, lib) on the side facing away from the other bearing (3, 4).