Refrigerated Showcase Compressor Speed Control for Energy Savings

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Solution Overview

Problem

Conventional refrigerated showcases control the compressor based on circulating air temperature, which can lead to inefficient cooling and energy wastage due to the lack of consideration for the temperature of the subject being refrigerated, especially when there is a significant difference in thermal capacities between the subject and the air.

Innovation Solution

A refrigerated showcase with a control device that uses temperature sensors to manage the compressor's operational rotations, stopping or reducing them based on predetermined temperature values to optimize cooling efficiency and energy savings, while maintaining air circulation to enhance cooling performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the compressor is controlled based on circulating air temperature, then the control system is simple, but the subject is not cooled efficiently or it takes time to cool the subject

Engineering Contradiction:
Improvecontrol system complexityVSAvoidcooling efficiency
Core Design Contradiction:
Device complexityVSProductivity

Solution Approach 1:

The patent applies feedback control by using a temperature sensor to detect subject temperature and feeding this information back to the control device. The control device then adjusts compressor operation based on the detected temperature, creating a closed-loop control system that efficiently cools the subject while maintaining appropriate system complexity.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent replaces simple on/off mechanical control with inverter-controlled variable speed compression. The inverter allows continuous adjustment of compressor speed based on temperature feedback, substituting mechanical switching with electronic control for more precise and efficient cooling.

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

2Temperature

If the compressor operates at high speed continuously, then cooling effect is enhanced, but energy consumption increases

Engineering Contradiction:
Improvecooling effectVSAvoidenergy consumption
Core Design Contradiction:
TemperatureVSUse of energy by moving object

Solution Approach 1:

The patent applies dynamics by making the compressor speed variable rather than fixed. The inverter controls the compressor to operate at different speeds depending on the cooling load and subject temperature, allowing the system to adapt dynamically to changing conditions and optimize energy consumption while maintaining cooling effect.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the operational parameters of the compressor by using an inverter to control rotation speed. Instead of operating at constant high speed, the compressor speed is adjusted as a variable parameter based on temperature feedback, enabling energy-efficient operation while maintaining adequate cooling effect.

Inventive Principle:
Principle #35Parameter changes

3Use of energy by moving object

If the compressor starts and stops frequently, then energy saving is achieved, but cooling stability deteriorates

Engineering Contradiction:
Improveenergy savingVSAvoidcooling stability
Core Design Contradiction:
Use of energy by moving objectVSStability of the object's composition

Solution Approach 1:

The patent applies continuity by keeping the compressor running continuously at variable speeds rather than频繁ly starting and stopping. The inverter enables the compressor to operate continuously at low speeds when cooling demand is low, maintaining cooling stability while still achieving energy savings compared to high-speed intermittent operation.

Inventive Principle:
Principle #20Continuity of useful 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 approach shortens cooling time and achieves energy-saving operations by ensuring the compressor operates at optimal speeds based on the subject's temperature, improving refrigeration effectiveness and reducing energy consumption.

Implementation Method 1

an evaporator; a fan for blowing air to the evaporator and circulating the air

Methodology Applied
Scientific EffectHeat exchange: Heat Exchanger

Implementation Method 2

a temperature sensor for detecting temperature of the air

Methodology Applied
Scientific EffectTemperature detection: Temperature Gradient

Data Source

PatentEP3611448B1Refrigerated showcase
Publication Date: 2021.10.27 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD
  • EP3611448B1 patent drawingFigure 1
  • EP3611448B1 patent drawingFigure 2
  • EP3611448B1 patent drawingFigure 3

AI summary

A refrigerated showcase 30 including: a refrigeration circuit 20 annularly formed by connecting, to one another through a refrigerant pipe, a compressor 1, a condenser 2, a decompression device 3 and an evaporator 4; a fan 5 for blowing air to the evaporator 4 and circulating the air; a temperature sensor 6 for detecting temperature of the air; and a control device 8, wherein the control device 8 stops the operation of the compressor 1 when detected temperature of the temperature sensor 6 reaches the predetermined value 1 during high speed operation of the compressor 1 in which the number of operational rotations thereof is constant, and thereafter, when the detected temperature of the temperature sensor 6 reaches the predetermined value 2, the compressor 1 is made to execute the high speed operation and, when the detected temperature of the temperature sensor 6 reaches the predetermined value 3, the number of operational rotations of the compressor 1 is controlled, and the number of operational rotations of the compressor 1 is reduced stepwisely. According to this, a cooling effect and energy-saving operation of the refrigerated showcase 30 are realized.