Compressor Oil Supply Control for Low-Speed Lubrication

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Solution Overview

Problem

Compressors face inadequate oil supply to components during low speed driving modes, leading to increased frictional losses and reduced efficiency, while excessive oil supply in high speed modes raises input, surface temperature, and suction/discharge issues.

Innovation Solution

A compressor design with a centrifugal oil supply unit and a crank shaft with a specific oil passage and feeder configuration, where the oil supply amount is optimized by controlling the shape of the oil passage and feeder to ensure sufficient oil supply in low speed modes and restrict excess supply in high speed modes by achieving a saturated state at predetermined speeds.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If the oil supply amount is increased through structural change of the crank shaft, then the oil supply in low speed driving mode is improved, but the oil supply in high speed driving mode becomes excessive

Engineering Contradiction:
Improveoil supply amountVSAvoidoil supply adaptability to driving mode
Core Design Contradiction:
Quantity of substanceVSAdaptability or versatility

Solution Approach 1:

The patent applies the dynamics principle by making the oil supply system adaptive to different driving speeds. The oil passage cross-sectional area is designed to vary along its length, creating different flow characteristics at different speeds. Additionally, the oil supply amount control unit dynamically adjusts the oil supply based on detected driving mode (low speed or high speed), allowing the system to optimize oil supply for each operating condition rather than using a fixed structural configuration.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent implements parameter changes by modifying the oil passage geometry (cross-sectional area varying along the length) and by dynamically changing the oil supply amount based on driving mode detection. The oil passage is designed with varying cross-sectional areas to create different flow resistance characteristics, and the control unit adjusts supply parameters (amount and timing) according to the detected operating speed, thereby adapting the system behavior to different operational requirements.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If the oil supply amount is increased in low speed driving mode, then the lubrication is improved, but the frictional loss and energy consumption increase in high speed driving mode

Engineering Contradiction:
Improvelubrication reliabilityVSAvoidenergy consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent applies feedback by incorporating a driving mode detection unit that monitors the actual operating conditions and provides information to the oil supply amount control unit. This closed-loop control allows the system to detect when the compressor is operating in low speed mode and increase oil supply accordingly, while automatically reducing oil supply when operating in high speed mode, thereby optimizing lubrication reliability while minimizing unnecessary energy consumption from excessive oil supply.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system dynamically adjusts oil supply based on real-time driving mode detection, making the lubrication system adaptive rather than static. This dynamic control ensures that oil supply matches actual lubrication needs at each operating speed, preventing both insufficient lubrication at low speeds and excessive oil consumption at high speeds.

Inventive Principle:
Principle #15Dynamics

3Quantity of substance

If the oil supply amount is increased through structural change, then the oil supply in low speed mode is sufficient, but the input power and surface temperature increase in high speed mode

Engineering Contradiction:
Improveoil supply amountVSAvoidinput power
Core Design Contradiction:
Quantity of substanceVSPower

Solution Approach 1:

The patent makes the oil supply system dynamic by implementing speed-dependent control. The oil supply amount control unit adjusts the supply amount based on detected driving mode, and the oil passage is designed with varying cross-sectional areas to create different flow characteristics at different speeds. This dynamic configuration ensures sufficient oil supply at low speeds while preventing excessive oil supply at high speeds that would increase input power requirements.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system changes operating parameters (oil supply amount, passage flow characteristics) based on driving mode. The varying cross-sectional area of the oil passage and the adjustable oil supply amount create different flow regimes and pressure drops suitable for each operating condition, thereby optimizing power consumption across the full speed range.

Inventive Principle:
Principle #35Parameter changes

4Reliability

If the oil supply amount is increased through structural change, then the lubrication is improved, but the suction amount and discharge amount are reduced in high speed driving mode

Engineering Contradiction:
Improvelubrication reliabilityVSAvoidgas compression capacity
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent uses feedback control where the driving mode detection unit monitors operating conditions and the oil supply amount control unit adjusts oil supply accordingly. This prevents excessive oil supply at high speeds that would contaminate the refrigerant and reduce gas compression capacity, while ensuring adequate lubrication at low speeds through increased oil supply.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The dynamic oil supply control system adapts lubrication levels to matching operational demands. At high speeds where gas compression capacity is critical, oil supply is reduced to minimize refrigerant contamination and maintain productivity. At low speeds where lubrication needs are relatively higher compared to compression output, oil supply is increased to ensure component protection.

Inventive Principle:
Principle #15Dynamics

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

Enhances oil supply to components during both low and high speed driving modes, improving performance by maintaining optimal oil levels and reducing frictional losses and operational inefficiencies.

Implementation Method 1

an oil supply unit configured to pump up the oil of the casing to the compression unit by using a centrifugal force generated by the rotation force of the driving motor

Methodology Applied
Scientific EffectCentrifugal force: Centrifugal Force

Data Source

PatentEP2478222B1compressor
Publication Date: 2020.06.10 LG ELECTRONICS INC
  • EP2478222B1 patent drawingFigure 1~2
  • EP2478222B1 patent drawingFigure 3~4
  • EP2478222B1 patent drawingFigure 5~6

AI summary

Disclosed is a compressor capable of having an enhanced performance by sufficiently supplying oil to components where sliding occurs not only in a high speed driving mode but also in a low speed driving mode. The compressor may increase an oil supply amount in a low speed driving mode, but may restrict an oil supply amount when a rotation speed of a driving motor reaches a predetermined speed in a constant or high speed driving mode, by setting the number of turns of an external groove to be approximately 1.75, and by forming an oil feeder in a conical shape.