Scroll Compressor Bush Assembly Groove Design for Oil Discharge

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Solution Overview

Problem

In scroll compressors, increased rotational speed leads to flow resistance issues with lubricating oil discharge, causing insufficient cooling and potential bearing burn, which hampers stable operation.

Innovation Solution

A bush assembly with a first groove section on the outer circumferential surface, a second groove section extending radially, and a discharge section passing through the weight section, facilitating smooth lubricating oil discharge and reducing the risk of inferior oil discharge and bearing damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the rotational speed of the crankshaft is increased, then the productivity of the scroll compressor is improved, but the flow resistance increases and the lubricating oil cannot be smoothly discharged

Engineering Contradiction:
Improverotational speedVSAvoidlubricating oil discharge
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The bush assembly is segmented into multiple functional sections: a bush for support, a ring section for structural connection, and a weight section for balance. Lubrication grooves are segmented into a first groove section and a second groove section that work together in sequence to guide oil flow, reducing resistance at each stage

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The lubrication path transitions from a two-dimensional surface groove to a three-dimensional discharge path through the weight section. The discharge section creates a radial flow path through the thickness of the bush assembly, adding a dimensional component to oil discharge that reduces flow resistance

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Productivity

If the rotational speed of the crankshaft is increased, then the productivity is improved, but the lubricating oil cannot be sufficiently cooled and the sliding bearing may burn

Engineering Contradiction:
Improverotational speedVSAvoidlubricating oil temperature
Core Design Contradiction:
ProductivityVSTemperature

Solution Approach 1:

The first and second groove sections act as intermediary channels that guide lubricating oil from the supply source through the bush assembly to the discharge section. This intermediary path ensures proper oil distribution and cooling function even at high rotational speeds

Inventive Principle:
Principle #24Intermediary (Mediator)

3Device complexity

If a narrow gap is formed between the balance weight and the turning scroll, then the device complexity is reduced, but the flow resistance increases and oil discharge becomes inferior

Engineering Contradiction:
Improvestructural simplicityVSAvoidlubricating oil discharge
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The ring section is nested on the outer circumferential side of the bush, and the weight section is nested on the outer circumferential side of the ring section. This nested arrangement allows the discharge section to be integrated within the existing structural layers without adding external complexity

Inventive Principle:
Principle #7Nested doll (Nesting)

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 described configuration ensures stable operation by enhancing lubricating oil discharge efficiency, preventing bearing damage, and maintaining compressor performance over time.

Implementation Method 1

lubricating oil provided for lubrication of the bush assembly is trapped by the first groove section formed in the outer circumferential surface of the bush and then flows toward the second groove section formed in the ring section

Methodology Applied
Scientific EffectLubrication: Lubrication

Implementation Method 2

As the crankshaft rotates, the lubricating oil arrives at a crankshaft eccentric shaft section through an oil supply hole

Methodology Applied
Scientific EffectCentrifugal force: Centrifugal Force

Data Source

PatentEP3103959B1Scroll compressor
Publication Date: 2017.11.29 MITSUBISHI HEAVY IND LTD
  • EP3103959B1 patent drawingFigure 1
  • EP3103959B1 patent drawingFigure 2
  • EP3103959B1 patent drawingFigure 3A~3B

AI summary

Provided is a scroll compressor that can be stably operated. The scroll compressor (100) includes a rotary shaft (4) extending along an axis (O1) and rotating about the axis (O1), a turning scroll (7) installed to be turnable around the axis (O1), a fixed scroll (6) configured to form a compression chamber (C) that compresses a coolant, and a bush assembly (10) configured to rotatably support the turning scroll (7). The bush assembly (10) includes a bush (101) fixed to the rotary shaft (4), a ring section (102) overhanging from an outer circumferential surface of the bush (101) at an outer circumferential side, and a weight section (103) formed at the outer circumferential side of the ring section (102), and the bush assembly (10) has a first groove section on the outer circumferential surface of the bush (101), a second groove section formed in the ring section (102) to come in communication with the first groove section, and a discharge section in communication with the second groove section.