Compressor Stator Oil Grooves for Lubrication Reliability

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Solution Overview

Problem

Conventional compressors experience oil shortage in the oil sump due to narrow passages, leading to inefficient lubrication of the compression mechanism and motor bearings, particularly when using high-viscosity lubricant oils with carbon dioxide as a refrigerant.

Innovation Solution

The compressor features a stator core with oil passage grooves cut into its outer peripheral surface, allowing lubricant oil to return to the oil sump through these grooves, which are designed to reach the inner periphery of the hollow circular cylindrical section, ensuring efficient oil circulation and preventing oil shortage. The grooves are semi-circular in shape and strategically positioned to secure magnetic flux paths while maintaining efficient oil return.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If passages penetrating through the motor are made narrow, then the motor structure is compact, but lubricant oil cannot return efficiently to the oil sump

Engineering Contradiction:

Improvemotor volumeVSAvoidlubrication reliability

Core Design Contradiction:

Volume of moving objectVSReliability

Solution Approach 1:

The patent divides the oil return path into multiple segments: oil passages in the motor and additional oil passage grooves in the stator core. This segmentation allows the system to maintain compact motor dimensions while providing alternative pathways for oil return, preventing oil shortage in the oil sump.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent adds oil passage grooves on the outer peripheral surface of the stator core, utilizing a different spatial dimension (radial direction) for oil return. This complements the axial oil passages in the motor, creating a three-dimensional oil circulation network that ensures reliable oil return without increasing motor volume.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Reliability

If high-viscosity lubricant oil is used with carbon dioxide refrigerant, then lubrication performance is improved, but oil return to the oil sump becomes difficult

Engineering Contradiction:

Improvelubrication performanceVSAvoidoil return efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent modifies the physical parameters of the oil passage system by adding grooves with specific dimensions (depth of 0.5-2.0mm, width of 1.0-3.0mm) on the stator core surface. These parameter changes create low-resistance pathways that facilitate the flow of high-viscosity oil, enabling efficient oil return while maintaining the use of high-viscosity lubricant oil for improved lubrication performance.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If oil passage grooves are added on the stator core, then oil return is improved, but manufacturing complexity increases

Engineering Contradiction:

Improveoil circulation reliabilityVSAvoidstator core manufacturing

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent replaces complex internal oil passage routing with simpler surface grooves on the stator core. These grooves can be formed using conventional machining or molding techniques, substituting for more complex mechanical oil return mechanisms and reducing manufacturing complexity while improving oil circulation reliability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 design effectively prevents oil shortage in the oil sump, ensuring reliable lubrication of the compressor's components and maintaining motor efficiency even with high-viscosity lubricant oils and carbon dioxide as a refrigerant.

Implementation Method 1

the oil passage grooves penetrate through one surface nearer to the oil sump of the stator core, and another surface thereof farther from the oil sump

Methodology Applied

Scientific EffectGravity: Gravitation

Implementation Method 2

it is possible to return the lubricant oil accumulated on the another-surface side of the stator core to the oil sump on the one-surface side of the stator core through the oil passage grooves

Methodology Applied

Scientific EffectPressure gradient: Pressure Gradient

Data Source

PatentUS9929607B2Compressor

Publication Date: 2018.03.27 DAIKIN INDUSTRIES LTD

AI summary

A compressor includes a hermetic container, a compression mechanism section disposed in the hermetic container, and a motor disposed in the hermetic container to drive the compression mechanism section. The motor has a rotor and a stator disposed so as to surround an outer periphery of the rotor. The stator includes a stator core and oil passage grooves. The stator core has a hollow circular cylindrical section and a plurality of circumferentially arranged teeth protruding radially inward from an outer peripheral surface of the hollow circular cylindrical section. The oil passage grooves are located radially outside of the teeth. The oil passage grooves are formed by cutting an outer peripheral surface of the hollow circular cylindrical section.