A method for operating a laundry drying machine equipped with a heat pump system and a laundry drying machine implementing said method
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Solution Overview
Problem
Laundry drying machines with heat pump systems face issues due to the delayed activation of overload protection devices, leading to increased drying cycle durations and customer dissatisfaction, as existing solutions primarily rely on temperature thresholds without effectively considering electrical current peaks.
Innovation Solution
A method for controlling laundry drying machines with a heat pump system that includes active and passive switching devices, using temperature and current thresholds to selectively operate the compressor and cooling fan, thereby preventing overload protection activation and reducing drying cycle duration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a passive overload protection device is used to prevent compressor damage, then compressor reliability is improved, but drying cycle duration increases due to the 40-minute delay before the device resets
Solution Approach 1:
The control unit performs preliminary monitoring of compressor temperature and electrical current before the overload protection device activates. When thresholds are approached, the control unit proactively switches off the compressor or activates cooling fans, preventing the 40-minute delay caused by passive device reset time and maintaining continuous drying operation
Solution Approach 2:
The system implements continuous feedback monitoring of compressor temperature and electrical current parameters. The control unit receives real-time data from sensors and dynamically adjusts compressor operation or cooling fan activation based on measured values, enabling preventive control that avoids overload protection activation and its associated delays
2Device complexity
If corrective actions are based only on compressor temperature, then device complexity is reduced, but protection effectiveness decreases due to inability to detect electrical current peaks
Solution Approach 1:
The control unit merges multiple monitoring functions into a single integrated system that simultaneously tracks both compressor temperature and electrical current parameters. This combination approach provides comprehensive protection against both thermal overload and electrical current peaks without requiring separate complex control systems
Solution Approach 2:
The control unit serves multiple functions: it controls the heat pump system operation, monitors compressor temperature, detects electrical current peaks, and activates cooling fans. This multi-functional approach consolidates protection mechanisms without increasing overall device complexity
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 method effectively prevents overload protection activation by considering both temperature and current thresholds, reducing the drying cycle duration and enhancing operational efficiency.
Implementation Method 1
at least one compressor cooling fan, controllable by the control unit... switching on said cooling fan if said temperature related to the compressor is above said one switch ON threshold temperature
Implementation Method 2
a heat pump system including a compressor, a first heat exchanger for cooling a refrigerant and heating the air stream
Implementation Method 3
an evaporator... The evaporator cools and dehumidifies the drying air leaving the drum
Implementation Method 4
a condenser... The condenser heats up the drying air while the evaporator cools and dehumidifies the drying air
Data Source
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AI summary
The invention relates to a method for controlling a laundry drying machine (1) equipped with a heat pump system (50) including a compressor (52) and equipped with at least a passive switching device (70), not controllable by a control unit (UC1), adapted to cut the power supplied to the compressor (52) when predetermined operative parameters thresholds are exceeded. The machine (1) further comprises at least one compressor cooling fan (60) and at least one temperature sensor (80, 85). The method comprises the steps of: activating the heat pump system (50) by switching on said compressor (52); detecting a machine temperature (Tm) related to temperature conditions of the laundry drying machine (1); detecting an electric parameter (Vd) related to the electric current absorbed by said compressor (52); detecting a temperature (Tr) related to the compressor (52); switching on said cooling fan (60) if said temperature (Tr) related to the compressor (52) is above one switch ON threshold temperature (Fan_Ton) selected among predetermined threshold temperatures (Fan_Ton); switching off said cooling fan (60) if said temperature (Tr) related to the compressor (52) is below one switch OFF threshold temperature (Fan_Toff) selected among predetermined threshold temperatures (Fan_Toff); maintaining said compressor (52) switched on or switching on said compressor (52) if said temperature (Tr) related to the compressor (52) is below one switch ON/OFF threshold temperature (Comp_Ton/off) among predetermined threshold temperatures (Comp_Ton/off); switching off said compressor (52) if said temperature related (Tr) to the compressor (52) is above, or equal to, one switch ON/OFF threshold temperature (Comp_Ton/off) among predetermined threshold temperatures (Comp_Ton/off). The predetermined threshold temperatures (Fan_Ton, Fan_Ton, Comp_Ton/off) are defined on the base of ranges of the machine temperature (Tm) and on the base of ranges of said electric parameter (Vd).