Non-Circular Oil Return Tube for Scroll Compressor

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Solution Overview

Problem

Existing scroll compressors face challenges in efficiently lubricating bearings due to limited oil flow and space constraints within the compressor housing, which can lead to reduced performance and increased wear.

Innovation Solution

The design incorporates a non-circular oil return tube with a stepped portion that fits snugly between the housing and motor, allowing substantial oil flow while being press-fit into tight spaces, and includes a short tubular portion with an O-ring seal to ensure effective lubrication and reduce vibration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If a circular oil return tube is used, then oil flow is maximized, but it cannot fit in the tight space between housing and motor

Engineering Contradiction:
Improveoil flow capacityVSAvoidtube geometry
Core Design Contradiction:
Volume of moving objectVSShape

Solution Approach 1:

The patent applies asymmetry by transitioning from a conventional circular oil return tube to a non-circular cross-section tube. The tube features a first dimension (height) and a second dimension (width) where the first dimension is greater than the second dimension, allowing it to fit within the constrained space between the housing and motor while maintaining adequate oil flow capacity through optimized dimensional proportions

Inventive Principle:
Principle #4Asymmetry

2Area of stationary object

If the oil return tube is made non-circular to fit tight space, then space utilization improves, but oil flow capacity may be reduced

Engineering Contradiction:
Improvespace utilizationVSAvoidoil flow volume
Core Design Contradiction:
Area of stationary objectVSQuantity of substance

Solution Approach 1:

The patent applies parameter changes by carefully controlling the dimensional parameters of the non-circular tube. The tube has a first dimension and a second dimension with specific proportional relationships, allowing the cross-sectional area to be optimized for both space utilization and oil flow capacity. The parameters are adjusted to ensure adequate oil return while fitting the constrained geometry

Inventive Principle:
Principle #35Parameter changes

3Manufacturing precision

If the oil return tube is press-fit into tight spaces, then installation precision improves, but manufacturing complexity increases

Engineering Contradiction:
Improvefit accuracyVSAvoidtube structure
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent applies segmentation by dividing the oil return tube into distinct portions with different functions: a first portion with a non-circular cross-section for press-fitting into the housing, and a second portion with a circular cross-section for connection to the motor. This segmentation allows each portion to be optimized for its specific function while simplifying the overall manufacturing process through modular construction

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP3390828B1Oil return with non-circular tube
Publication Date: 2020.06.24 BITZER KUEHLMASCHINENBAU GMBH
  • EP3390828B1 patent drawingFigure 1
  • EP3390828B1 patent drawingFigure 2
  • EP3390828B1 patent drawingFigure 3

AI summary

A scroll compressor includes a housing and scroll compressor bodies disposed in the housing. The scroll bodies include first and second scroll bodies. The first and second scroll bodies have respective bases and respective scroll ribs that project from the respective bases. The scroll ribs mutually engage, such that the second scroll body is movable relative to the first scroll body for compressing fluid. An oil return tube delivers oil from an upper region of the housing to an oil sump in a lower region of the housing. The relatively longer portion is positioned substantially vertically within the housing. The relatively longer tubular portion is non-circular and may have at least one stepped portion which corresponds to a step in the interior surface of the housing. In some embodiments, the oil return tube has a short tubular portion attached at one end to a relatively longer tubular portion.