Crankshaft Oil Gallery Lubrication for Scroll Compressor Bearings

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Solution Overview

Problem

In scroll compressors, particularly in multi-stage or parallel-flow designs, orbiting scroll radial bearings face challenges in lubrication that can adversely affect compressor efficiency, especially when high oil supply pressures are required for hydrostatic thrust bearings, leading to excessive oil flow through journal bearings and efficiency losses.

Innovation Solution

A lubrication system that utilizes a high-pressure lubricating fluid sump and an axial lubricating fluid gallery through the crankshaft to supply lubricating fluid to both stages of orbiting scroll radial bearings, allowing for efficient lubrication without the need for an oil pump and minimizing excessive oil flow through radial bearings.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If high oil supply pressure is supplied to hydrostatic thrust bearings to maintain kinematic stability, then thrust bearing reliability is improved, but excessive oil flow through journal bearings occurs causing efficiency loss

Engineering Contradiction:

Improvethrust bearing reliabilityVSAvoidcompressor efficiency

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The lubrication system is segmented into separate supply paths: a high-pressure oil supply path for the hydrostatic thrust bearing and a low-pressure oil supply path for the journal bearing. This segmentation allows each bearing to receive oil at its required pressure independently, resolving the contradiction between thrust bearing reliability and compressor efficiency.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different oil supply pressures are provided to different locations based on their specific requirements: high pressure (e.g., 200 psid) to the hydrostatic thrust bearing for stability, and low pressure (e.g., 30-70 psid) to the journal bearing to avoid excessive flow and efficiency loss. This local differentiation resolves the pressure conflict.

Inventive Principle:

Principle #3Local quality

2Reliability

If an oil pump is added to supply oil to both radial bearings, then lubrication reliability is improved, but power loss increases

Engineering Contradiction:

Improvelubrication reliabilityVSAvoidcompressor power loss

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The system uses the high-pressure oil supply intended for the hydrostatic thrust bearing to also lubricate the journal bearing through a gallery, eliminating the need for a separate oil pump. The oil circulation system serves itself by utilizing existing pressure differentials and pathways, thus improving reliability without adding the power loss associated with an oil pump.

Inventive Principle:

Principle #25Self-service

3Reliability

If high oil flow rate is supplied to journal bearings, then bearing lubrication is improved, but compressor efficiency decreases

Engineering Contradiction:

Improvejournal bearing lubricationVSAvoidcompressor efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The oil supply pressure parameter is changed and optimized for each bearing type: low pressure (30-70 psid) for journal bearings to achieve adequate lubrication with minimal flow, and high pressure (200 psid) for hydrostatic thrust bearings. This parameter optimization ensures proper lubrication while minimizing the harmful effects of excessive oil flow on compressor efficiency.

Inventive Principle:

Principle #35Parameter changes

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 solution effectively lubricates orbiting scroll radial bearings in scroll compressors, maintaining compressor efficiency by optimizing oil supply pressures and flow rates, reducing power losses, and accommodating both hydrodynamic and hydrostatic thrust bearings without the need for an oil pump.

Implementation Method 1

a lubricating fluid gallery extending axially through the crankshaft between the first stage orbiting scroll and the second stage orbiting scroll

Methodology Applied

Scientific EffectFluid flow through gallery:

Implementation Method 2

hydrostatic (balanced piston) type orbiting scroll thrust bearing... High oil feed pressures force extra oil through the compressor journal bearings... High oil feed pressures... in order to maintain the kinematic stability of the orbiting scroll or otherwise offset the axial forces due to compression

Methodology Applied

Scientific EffectHydrostatic pressure: Pressure Increase

Implementation Method 3

Conventional hydrodynamic type orbiting scroll radial bearings may be lubricated via oil passages in the orbiting scroll baseplate... When these bearings are journal bearings, for example, they may require high oil flow rates

Methodology Applied

Scientific EffectHydrodynamic lubrication: Lubrication

Data Source

PatentUS10197059B2Double-ended scroll compressor lubrication of one orbiting scroll bearing via crankshaft oil gallery from another orbiting scroll bearing

Publication Date: 2019.02.05 TRANE INTERNATIONAL INC

AI summary

A scroll compressor orbiting scroll bearing lubrication system includes a scroll compressor crankshaft having a lubricating fluid gallery extending therethrough between a first stage orbiting scroll and a second stage orbiting scroll. The first stage employs an orbiting scroll radial bearing and an orbiting scroll hydrodynamic thrust bearing, while the second stage employs an orbiting scroll radial bearing and an orbiting scroll hydrostatic thrust bearing. Lubricating fluid is supplied to the second stage orbiting scroll radial bearing via the lubricating fluid gallery.