Multi-Compressor Air Conditioner Oil Redistribution by Level Detection

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

In multi-compressor air conditioner systems, it is challenging to accurately determine and maintain the oil level in each compressor, leading to inefficient oil return operations that consume energy and may not provide effective cooling or heating, especially when the oil level is sufficient in some compressors but insufficient in others.

Innovation Solution

An operating method that includes oil level detection in each compressor, redistribution of oil between compressors with varying levels, and an oil collection operation based on preset levels, using a network of suction and return pipes and oil separators to optimize oil distribution and minimize energy consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If oil return operation is performed at predetermined periods, then oil level maintenance is attempted, but energy is wasted and cooling/heating is interrupted even when oil level is sufficient

Engineering Contradiction:
Improveoil level maintenanceVSAvoidenergy consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The system uses oil level detecting devices in each compressor to provide real-time feedback on oil levels. The control unit receives this feedback and decides whether to initiate oil return operation based on actual oil level conditions rather than fixed timing, thereby avoiding unnecessary operations when oil levels are sufficient.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent replaces the conventional time-based mechanical control system with an automated sensor-based detection and control system. Oil level detecting devices continuously monitor oil levels and transmit signals to the control unit, which automatically activates compressors for oil return only when needed, eliminating the need for predetermined periodic operations.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If oil return operation is performed frequently, then oil level is maintained, but cooling or heating cannot be provided and energy is consumed unnecessarily

Engineering Contradiction:
Improveoil level adequacyVSAvoidcooling/heating availability
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The control unit continuously monitors oil level signals from detecting devices and only initiates oil return operation when actual oil level falls below the preset level. This feedback mechanism prevents frequent unnecessary operations and ensures cooling or heating is provided unless truly needed for oil level correction.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

Each compressor is equipped with its own oil level detecting device that enables the system to self-monitor and self-correct oil levels autonomously. The control unit automatically activates specific compressors for oil return based on detected conditions, eliminating the need for manual intervention or fixed scheduling.

Inventive Principle:
Principle #25Self-service

3Ease of operation

If oil is redistributed through heat exchangers, then oil can be moved between compressors, but system complexity and operation time increase

Engineering Contradiction:
Improveoil distribution capabilityVSAvoidpipe network complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The suction pipes and oil return pipes are designed to serve multiple functions: they transport refrigerant during normal cooling/heating operations and simultaneously serve as oil return pathways when needed. This multi-functionality eliminates the need for separate dedicated oil return lines, reducing system complexity while maintaining oil distribution capability.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system pre-establishes oil return pathways through the existing suction and discharge pipe networks during system design. When oil level imbalance is detected, the control unit simply activates the appropriate compressors to pump oil through these pre-configured pathways, avoiding the need for complex additional infrastructure.

Inventive Principle:
Principle #10Preliminary action

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 method reduces the time required for oil collection operations, ensures efficient oil distribution, and maintains optimal oil levels in all compressors, thereby improving the energy efficiency and performance of the air conditioner.

Implementation Method 1

an oil level detecting device that detects an oil level in the casing

Methodology Applied
Scientific EffectBuoyancy: Archimedes' Principle (Buoyancy)

Implementation Method 2

at least one first heat exchanger that intakes a working fluid from the plurality of compressors; at least one second heat exchanger, through which the working fluid passes

Methodology Applied
Scientific EffectPhase change: Phase Change

Data Source

PatentEP2375193B1Operating method for air conditioner with multiple compressors
Publication Date: 2013.03.06 LG ELECTRONICS INC
  • EP2375193B1 patent drawingFigure 1
  • EP2375193B1 patent drawingFigure 2
  • EP2375193B1 patent drawingFigure 3

AI summary

An air conditioner and a method of operating the same are provided. The air conditioner may include a plurality of compressors (100,100',100''), each of which may include a casing that stores oil therein, and an oil level detecting device (102,102',102'') that detects an oil level within the casing. Once oil levels within each of the plurality of compressors are detected, oil may be redistributed between the plurality of compressors without interrupting a normal operation of the air conditioner. Oil may be transferred from a compressor having an oil level greater than a desired amount to a compressor having an oil level less than the desired amount. If there remains a compressor that contains an insufficient amount of oil after redistributing the oil among the plurality of compressors, an oil collecting operation may be performed.