Linear compressor and method for controlling linear compressor

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Solution Overview

Problem

Linear compressors face efficiency reduction and piston wear due to groove clogging in the cylinder, primarily caused by foreign matter and oil, which leads to friction between the piston and cylinder, especially under low temperature conditions.

Innovation Solution

A control method for the linear compressor that involves preheating the motor before operation by adjusting the inverter to increase the temperature, using a controller to manage DC and AC currents based on temperature sensors and motor resistance, ensuring the groove remains unclogged and reducing viscosity of oils, thereby preventing friction and wear.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the linear compressor operates under low temperature conditions, then the viscosity of oil increases causing groove clogging, but preheating the motor increases energy consumption

Engineering Contradiction:
Improveprevention of groove cloggingVSAvoidenergy consumption during preheating
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The controller performs a preheating operation before the linear compressor starts normal operation. The controller applies a DC current to the motor through the inverter, heating the motor and surrounding components to reduce oil viscosity and prevent groove clogging before refrigerant flows into the cylinder

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The controller changes the electrical parameters by applying DC current instead of normal AC operation current during the preheating phase. This parameter change enables the motor to function as a heating element, raising the temperature of internal components and reducing oil viscosity to prevent clogging

Inventive Principle:
Principle #35Parameter changes

2Reliability

If the groove in the cylinder is clogged by foreign matter and oil, then friction between piston and cylinder increases, but adding preventive structures increases device complexity

Engineering Contradiction:
Improveprevention of piston wearVSAvoidstructural complexity of preventive mechanisms
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The system performs preliminary heating before operation to reduce oil viscosity and prevent it from clogging the groove. This preventive action addresses the root cause of piston wear without requiring additional mechanical structures

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The motor serves dual purposes: it acts as both the driving motor and as a heating element during the preheating operation. The motor's own electrical resistance generates heat to warm the internal components, eliminating the need for separate heating devices or complex preventive structures

Inventive Principle:
Principle #25Self-service

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 preheating operation effectively prevents groove clogging, maintains compressor efficiency, and extends the lifespan of the piston and compressor components by minimizing friction and wear, especially under low temperature conditions.

Implementation Method 1

A linear compressor and a control method for the linear compressor... preheating the motor before operation by adjusting the inverter to increase the temperature... using a controller to manage DC and AC currents

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Data Source

PatentEP3613984B1Linear compressor and method for controlling linear compressor
Publication Date: 2021.02.17 LG ELECTRONICS INC
  • EP3613984B1 patent drawingFigure 1
  • EP3613984B1 patent drawingFigure 2
  • EP3613984B1 patent drawingFigure 3~4

AI summary

Linear compressor for an electronic device such as a refrigerator, a laundry treating apparatus, an air conditioner, an air purifier or the like, the linear compressor comprising a cylinder (141), and a piston (142) reciprocating within the cylinder, wherein the cylinder includes at least a groove (220) for supplying a gas to the space between the cylinder and the piston to perform a gas bearing function. The linear compressor further includes a motor (M), an inverter configured to perform a switching operation to transmit electric power to the motor, and a controller, wherein the controller is configured to receive temperature information from the electronic device and control the inverter to preheat the motor based on the received temperature information.