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ITVA20110031A1 - PROCEDURE FOR THE DEFROSTING OF AN EVAPORATOR AND REFRIGERATOR SUITABLE FOR IMPLEMENTING THIS PROCEDURE - Google Patents

PROCEDURE FOR THE DEFROSTING OF AN EVAPORATOR AND REFRIGERATOR SUITABLE FOR IMPLEMENTING THIS PROCEDURE Download PDF

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Publication number
ITVA20110031A1
ITVA20110031A1 IT000031A ITVA20110031A ITVA20110031A1 IT VA20110031 A1 ITVA20110031 A1 IT VA20110031A1 IT 000031 A IT000031 A IT 000031A IT VA20110031 A ITVA20110031 A IT VA20110031A IT VA20110031 A1 ITVA20110031 A1 IT VA20110031A1
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IT
Italy
Prior art keywords
temperature
evaporator
compressor
defrost
defrosting
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Application number
IT000031A
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Italian (it)
Inventor
Auria Mariagrazia D
Gioele Rivis
Jutta Ziermaier
Original Assignee
Whirlpool Co
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Publication date
Application filed by Whirlpool Co filed Critical Whirlpool Co
Priority to IT000031A priority Critical patent/ITVA20110031A1/en
Publication of ITVA20110031A1 publication Critical patent/ITVA20110031A1/en

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Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25DREFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
    • F25D21/00Defrosting; Preventing frosting; Removing condensed or defrost water
    • F25D21/002Defroster control
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25DREFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
    • F25D2700/00Means for sensing or measuring; Sensors therefor
    • F25D2700/10Sensors measuring the temperature of the evaporator

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Defrosting Systems (AREA)

Description

 La  presente  invenzione  riguarda  un  procedimento  per  il  controllo  dello  sbrinamento  di  un  evaporatore posto  in una  cavità di un  frigorifero provvisto di un  circuito  refrigerante  con un  compressore  il  cui  azionamento  on/off  regola  la  temperatura  dell’evaporatore  fra  un  valore  massimo e minimo predeterminati  in relazione alla temperatura desiderata nella cavità, ed  in  cui  à ̈  previsto  l’utilizzo  di  un  sensore  di  temperatura  dell’evaporatore  ed  il  compressore  à ̈  disattivato  in  modo  tale  che  la  temperatura  dell’evaporatore  raggiunga  un  valore  pari  alla  temperatura di sbrinamento. La presente invenzione riguarda inoltre un frigorifero in cui viene  attuato il suddetto procedimento.  The present invention relates to a process for controlling the defrosting of an evaporator placed in a cavity of a refrigerator provided with a refrigerant circuit with a compressor whose on / off operation regulates the evaporator temperature between a predetermined maximum and minimum value in relation to the desired temperature in the cavity, and in which the use of an evaporator temperature sensor is foreseen and the compressor is deactivated so that the evaporator temperature reaches a value equal to the defrost temperature . The present invention also relates to a refrigerator in which the above process is carried out.

Un procedimento di sbrinamento ed un frigorifero del tipo suddetto sono noti da US 4689965.  Tale  documento  descrive  un  frigorifero  in  cui  à ̈  presente  un  controllo  atto  a  determinare  l’intervallo  di  tempo  in  cui,  a  compressore  spento,  l’evaporatore  si  mantiene  ad  una  temperatura  di  circa  0°C,  detto  intervallo  essendo  indicativo  della  quantità  di  ghiaccio/brina  depositata sull’evaporatore. Tale valore di tempo Ã ̈ utilizzato dal controllo per stabilire quando  ripetere  lo sbrinamento, per evitare sia che  l’accumulo di brina sia  insufficiente a giustificare  uno sbrinamento sia che si accumuli troppa brina sull’evaporatore diminuendone le prestazioni.  Questa  modalità  di  funzionamento,  sebbene  efficace  per  misurare  la  quantità  di  brina  sull’evaporatore, presenta la difficoltà di dover predisporre un algoritmo predittivo. Inoltre con  questo procedimento noto vi Ã ̈ il rischio che venga effettuato lo sbrinamento senza tener conto  se  sono  intervenuti  fatti  esterni  che  hanno  modificato  le  condizioni  (apertura  della  porta,  inserimento di cibi caldi e/o ad elevato contenuto di umidità ecc.). In tal caso il tempo valutato  dall’algoritmo predittivo potrebbe essere troppo lungo o troppo corto, diminuendo l’efficienza  energetica dell’elettrodomestico. Per ovviare a questo  inconveniente Ã ̈ necessario predisporre  ulteriori sensori (ad esempio di apertura della porta, di temperatura all’interno della cavità ecc.)  ed un software che tenga conto di tali segnali, con una conseguente complicazione costruttiva  ed aumento di costo dell’elettrodomestico.  A defrosting process and a refrigerator of the above type are known from US 4689965. This document describes a refrigerator in which there is a control suitable for determining the time interval in which, with the compressor off, the evaporator remains at a temperature of about 0 ° C, said interval being indicative of the quantity of ice / frost deposited on the evaporator. This time value is used by the controller to establish when to repeat the defrost, to avoid both the accumulation of frost being insufficient to justify a defrosting and that too much frost accumulating on the evaporator, reducing its performance. This operating mode, although effective for measuring the amount of frost on the evaporator, presents the difficulty of having to set up a predictive algorithm. Furthermore, with this known procedure there is a risk that defrosting will be carried out without taking into account whether external events have occurred that have changed the conditions (opening the door, inserting hot and / or high-humidity foods, etc.). In this case, the time evaluated by the predictive algorithm could be too long or too short, reducing the energy efficiency of the appliance. To overcome this drawback it is necessary to provide additional sensors (for example for door opening, temperature inside the cavity, etc.) and software that takes these signals into account, with a consequent constructive complication and an increase in the cost of the € ™ household appliance.

Scopo della presente invenzione Ã ̈ predisporre un procedimento del tipo indicato all’inizio della  descrizione  che  non  presenti  i  suddetti  inconvenienti  e  sia  di  semplice  ed  economica  realizzazione. Secondo  l’invenzione,  tale scopo Ã ̈  raggiunto grazie alle caratteristiche elencate  nelle allegate rivendicazioni.  The purpose of the present invention is to provide a process of the type indicated at the beginning of the description which does not present the aforementioned drawbacks and is simple and economical to carry out. According to the invention, this object is achieved thanks to the characteristics listed in the attached claims.

Una delle caratteristiche principali del procedimento secondo  l’invenzione Ã ̈ un confronto del  tempo di permanenza  a  0°C  con un  valore predeterminato  in modo  da  avere un  sensore di  brina  virtuale  atto  a  reagire  a  qualsiasi  influenza  esterna.  Detto  confronto  tra  il  tempo  di  sbrinamento ed un valore di soglia predeterminato discrimina  in tempo reale se  l’evaporatore  deve essere sbrinato oppure no. Tale semplice confronto non presenta complicazioni a livello di  algoritmo e può essere facilmente implementato sull’attuale scheda di controllo del frigorifero  senza aumentarne il costo. Se il tempo di permanenza a 0°C Ã ̈ superiore a detto valore di soglia,  la  scheda  elettronica  di  controllo  mantiene  disattivato  il  compressore  fino  a  quando  la  temperatura dell’evaporatore ha raggiunto un valore di soglia predeterminato, superiore a 0°C,  in  modo  tale  da  garantire  un  completo  sbrinamento.  Se  il  tempo  di  permanenza  a  0°C  à ̈  inferiore  al  valore  di  soglia,  la  scheda  elettronica  provvede  a  riattivare  il  normale  funzionamento del compressore.  One of the main features of the process according to the invention is a comparison of the residence time at 0 ° C with a predetermined value in order to have a virtual frost sensor able to react to any external influence. Said comparison between the defrost time and a predetermined threshold value discriminates in real time whether the evaporator must be defrosted or not. This simple comparison presents no algorithm complications and can be easily implemented on the current refrigerator control board without increasing its cost. If the residence time at 0 ° C is higher than said threshold value, the electronic control board keeps the compressor off until the evaporator temperature has reached a predetermined threshold value, higher than 0 ° C, in such a way as to guarantee complete defrosting. If the residence time at 0 ° C is lower than the threshold value, the electronic board reactivates the normal operation of the compressor.

In tal modo  lo sbrinamento completo viene effettuato solo quando necessario, tenendo conto  automaticamente  anche  degli  eventi  esterni  eventualmente  verificatisi  nel  periodo  tra  due  successivi sbrinamenti. La verifica sulla necessità dello sbrinamento completo viene realizzata in  una fase di semi†sbrinamento in cui Ã ̈ sufficiente venga sbrinata solo la sonda di temperatura e  l’area  dell’evaporatore  immediatamente  circostante.  Inoltre  si  à ̈  rilevato  che  con  il  procedimento secondo  l’invenzione si Ã ̈ diminuita  la stratificazione di  temperatura all’interno  della cella, definita come differenza tra le temperature massima e minima nella cella.  In this way, complete defrosting is carried out only when necessary, automatically taking into account any external events that may have occurred in the period between two subsequent defrosts. The verification of the need for complete defrosting is carried out in a semi-defrosting phase in which it is sufficient to defrost only the temperature probe and the immediately surrounding evaporator area. Furthermore, it has been found that with the process according to the invention, the temperature stratification inside the cell has been reduced, defined as the difference between the maximum and minimum temperatures in the cell.

Il procedimento secondo  l’invenzione può essere attuato sia portando  l’evaporatore a 0°C ad  ogni ciclatura del compressore (cioà ̈ verificando ad ogni risalita di temperatura dell’evaporatore  se vi Ã ̈ necessità di uno sbrinamento) oppure  facendo ciclare  il compressore  tra  temperature  inferiori  a  0°C  e  facendo  risalire  la  temperatura  dell’evaporatore  solamente  dopo  un  tempo  predeterminato o un numero predeterminato di ciclature del compressore.  The procedure according to the invention can be carried out either by bringing the evaporator to 0 ° C at each cycling of the compressor (that is, by checking at each temperature rise of the evaporator if there is a need for defrosting) or by cycling the compressor between temperatures below 0 ° C and making the evaporator temperature rise only after a predetermined time or a predetermined number of compressor cycles.

Infine,  il procedimento secondo  l’invenzione può essere utilizzato sia  in  frigoriferi di tipo â€œnofrost†  (in  cui  l’evaporatore  à ̈  investito  da  un  flusso  d’aria  circolante)  sia  in  frigoriferi  di  tipo  statico.  Finally, the process according to the invention can be used both in â € œnofrostâ € type refrigerators (in which the evaporator is hit by a circulating air flow) and in static type refrigerators.

Ulteriori vantaggi e caratteristiche di un procedimento e di un frigorifero secondo  la presente  invenzione risulteranno evidenti dalla descrizione dettagliata seguente, fornita a puro titolo di  esempio non limitativo, con riferimento ai disegni allegati in cui:  Further advantages and characteristics of a process and of a refrigerator according to the present invention will become evident from the following detailed description, provided purely by way of non-limiting example, with reference to the attached drawings in which:

†La figura 1 Ã ̈ una vista schematica di un frigorifero no†frost secondo l’invenzione;  †La  figura  2  à ̈  un  diagramma  in  cui  à ̈  riportato  l’andamento  della  temperatura  dell’evaporatore  di  un  frigorifero  secondo  una  prima  forma  di  attuazione  dell’invenzione;  â € Figure 1 is a schematic view of a frost-free refrigerator according to the invention; â € Figure 2 is a diagram showing the temperature trend of the evaporator of a refrigerator according to a first embodiment of the invention;

†La  figura  3  à ̈  uno  schema  a  blocchi  dell’algoritmo  di  funzionamento  del  frigorifero  secondo l’invenzione;   â € Figure 3 is a block diagram of the refrigerator operating algorithm according to the invention;

†La  figura 4 Ã ̈ un diagramma simile alla  figura 2 ed  illustra  l’andamento di temperatura  secondo una diversa forma di attuazione secondo l’invenzione; e  â € Figure 4 is a diagram similar to Figure 2 and illustrates the temperature trend according to a different embodiment according to the invention; And

†La figura 5 Ã ̈ un diagramma simile alla figura 4 ma riferito ad un frigorifero no†frost    in  cui lo sbrinamento completo Ã ̈ realizzato ad ogni ciclatura del compressore.  â € Figure 5 is a diagram similar to figure 4 but referring to a frost-free refrigerator in which complete defrosting is performed at each cycling of the compressor.

Con  riferimento ai disegni, con 10 Ã ̈  indicato un  frigorifero di  tipo no†frost avente una cavità  10a, un circuito refrigerante 12 ed un circuito elettronico di controllo 14. Il circuito refrigerante  12 presenta un  compressore 12a, un  condensatore 12b ed un evaporatore 12c   provvisto di  sensore di temperatura 16. L’evaporatore 12c Ã ̈ provvisto di ventilatore 18 atto a garantire un  flusso di aria refrigerata all’interno della cavità 10a.   With reference to the drawings, 10 indicates a frost-free refrigerator having a cavity 10a, a refrigerant circuit 12 and an electronic control circuit 14. The refrigerant circuit 12 has a compressor 12a, a condenser 12b and an evaporator 12c equipped with temperature sensor 16. The evaporator 12c is equipped with a fan 18 to guarantee a flow of refrigerated air inside the cavity 10a.

Al  circuito  elettronico  di  controllo  14  sono  collegati  il  compressore  12a  ed  il  sensore  di  temperatura 16. Com’à ̈ illustrato in figura 2, in una prima forma di attuazione dell’invenzione il  compressore Ã ̈ azionato  in modalità on/off tra una temperatura di ON dell’evaporatore pari a  circa  †5°C  ed  una  temperatura  di  OFF  pari  a  circa  †11°C.  Queste  due  temperature  sono  ovviamente  in relazione sia alla temperatura  impostata dall’utente e memorizzata nel circuito  elettronico di controllo 14  sia alla  temperatura ambiente, e possono quindi variare. Dopo un  tempo predeterminato di  funzionamento on/off del compressore, che dipende dalla tipologia  del frigorifero, ad esempio 60 minuti, il compressore 12a viene mantenuto spento anche dopo il  raggiungimento della temperatura di â€œON†, fino a quando la temperatura dell’evaporatore 12c  raggiunge  la  temperatura  di  sbrinamento  (0°C).  Questa  fase  à ̈  illustrata  in  figura  2  con  il  riferimento A. In questa condizione  il controllo elettronico 14 misura  il tempo  in cui  il sensore  16 si mantiene a 0°C e  lo confronta con un valore memorizzato di soglia. Nella condizione â€œA†  detto  tempo misurato  à ̈  inferiore  al  valore  di  soglia  e  pertanto  a  questo  semi†sbrinamento  preliminare (in cui solo una porzione dell’evaporatore nell’intorno del sensore di temperatura si  libera  dalla  brina/ghiaccio)  non  segue  un  successivo  innalzamento  della  temperatura  atto  a  garantire uno sbrinamento completo dell’evaporatore, bensì una riattivazione del compressore  12a.  The compressor 12a and the temperature sensor 16 are connected to the electronic control circuit 14. As illustrated in Figure 2, in a first embodiment of the invention the compressor is operated in on / off mode between a evaporator ON temperature of approximately â € 5 ° C and an OFF temperature of approximately â € 11 ° C. These two temperatures are obviously in relation both to the temperature set by the user and memorized in the electronic control circuit 14 and to the ambient temperature, and can therefore vary. After a predetermined on / off operating time of the compressor, which depends on the type of refrigerator, for example 60 minutes, the compressor 12a is kept off even after reaching the `` ON '' temperature, until the temperature of the evaporator 12c reaches the defrost temperature (0 ° C). This phase is illustrated in Figure 2 with the reference A. In this condition the electronic control 14 measures the time in which the sensor 16 remains at 0 ° C and compares it with a memorized threshold value. In the â € œAâ € condition, said measured time is lower than the threshold value and therefore this preliminary semi-defrost (in which only a portion of the evaporator around the temperature sensor is freed from the frost / ice). this is followed by a subsequent increase in temperature to ensure complete defrosting of the evaporator, but rather a reactivation of the compressor 12a.

Nella condizione illustrata in figura 2 con il riferimento B, il tempo di semi†sbrinamento (in cui la  temperatura  si mantiene a 0°C per effetto del cambiamento di  stato  solido†liquido)  supera  il  valore di soglia e pertanto il controllo 14 provvede a ritardare l’accensione del compressore 12a  fino  a  quando  al  temperatura  dell’evaporatore  non  raggiunge  un  valore  predeterminato  (ad  esempio 4,5°C) atto a garantire un completo sbrinamento dell’evaporatore.  Il tempo di soglia  può  variare  in  relazione  alla  tipologia di  frigorifero,  ed  à ̈  generalmente  compreso  tra    3  e  7  minuti.  Inoltre  la  posizione  del  sensore  di  temperatura  16  à ̈  scelta  in  modo  tale  da  corrispondere ad una zona significativa dell’evaporatore che generalmente si sbrina per ultima.  In the condition illustrated in figure 2 with reference B, the semi-defrost time (in which the temperature is maintained at 0 ° C due to the change in solid-liquid state) exceeds the threshold value and therefore the control 14 provides for delay the ignition of compressor 12a until the evaporator temperature reaches a predetermined value (for example 4.5 ° C) to ensure complete defrosting of the evaporator. The threshold time can vary according to the type of refrigerator, and is generally between 3 and 7 minutes. Furthermore, the position of the temperature sensor 16 is chosen in such a way as to correspond to a significant area of the evaporator which generally defrosts last.

In  figura  3  à ̈  illustrato un  diagramma  a  blocchi  che  illustra  l’algoritmo  di  funzionamento  del  controllo elettronico 14. Quando  il  frigorifero Ã ̈ acceso e  funziona normalmente  (blocco 1), si  verifica  (blocchi  2  e  3)  se  il  tempo  di  funzionamento  totale  del  frigorifero  o  del  solo  compressore  nella  sua  condizione  di  “ON†  supera  un  tempo  predeterminato,  nell’esempio  quattro  ore.  In  caso  di  superamento  di  tale  tempo  massimo  predeterminato,  si  inizia  a  monitorare il tempo di permanenza dell’evaporatore a 0°C (blocchi 5 e 6). Il circuito elettronico  di  controllo  14  disattiva  il  contatore  (blocco  8)  quando  l’evaporatore  ha  raggiunto  una  predeterminata  temperatura  leggermente  superiore  a  0°C,  nell’esempio  descritto  0,7°C.  Il  tempo misurato  viene  quindi  confrontato  (blocco  9)  con  un  valore  di  soglia  predeterminato  (indicato  nello  schema  con  il  riferimento  “N†);  al  superamento  di  tale  valore  di  soglia  il  compressore viene mantenuto spento vino a quando  l’evaporatore non raggiunge un secondo  valore  di  soglia  che  garantisce  un  completo  sbrinamento,  ad  esempio  4,5°C.  Se  tale  tempo  misurato non supera  il valore N, successivamente a questo semi†sbrinamento viene  ripreso  il  ciclo di controllo al blocco 1.  Figure 3 shows a block diagram illustrating the operating algorithm of the electronic control 14. When the refrigerator is on and operating normally (block 1), it occurs (blocks 2 and 3) whether the operating time total of the refrigerator or compressor alone in its â € œONâ € condition exceeds a predetermined time, in the example four hours. If this predetermined maximum time is exceeded, the evaporator residence time at 0 ° C is monitored (blocks 5 and 6). The electronic control circuit 14 deactivates the counter (block 8) when the evaporator has reached a predetermined temperature slightly above 0 ° C, in the example described 0.7 ° C. The measured time is then compared (block 9) with a predetermined threshold value (indicated in the diagram with the reference â € œNâ €); when this threshold value is exceeded, the compressor is kept off wine until the evaporator reaches a second threshold value which guarantees complete defrosting, for example 4.5 ° C. If this measured time does not exceed the N value, after this semi-defrost the control cycle in block 1 is resumed.

In  figura  4  à ̈  illustrata  una  modalità  di  funzionamento  in  una  seconda  forma  di  attuazione  dell’invenzione, in cui la temperatura del compressore viene fatta risalire a 0°C ad ogni ciclatura  (partendo da una  temperatura di â€œON† ad esempio nell’intorno di  †12°C).  In questa  forma di  attuazione il controllo sulla necessità di sbrinamento viene effettuato ad ogni ciclo ON/OFF del  compressore (nell’esempio di figura 4 per tutti i quattro cicli considerati non si Ã ̈ riscontrata la  necessità di uno sbrinamento totale dell’evaporatore  12c). Si Ã ̈ riscontrato che con la modalità  di  funzionamento  secondo  l’invenzione  la  temperatura del prodotto alimentare TP contenuto  nel  frigorifero  corrisponde  sostanzialmente  alla  temperatura media  del  frigorifero,  con  una  differenza tra la temperatura massima nella cavità (TB) e temperatura minima (TA), la cosiddetta  “stratificazione† di temperatura all’interno della cavità, dell’ordine di 2,1°C (zona di riferimento  K in figura 4).  Figure 4 illustrates an operating mode in a second embodiment of the invention, in which the compressor temperature is made to rise to 0 ° C at each cycling (starting from a temperature of â € œONâ € for example in the Around â € 12 ° C). In this embodiment, the control on the need for defrosting is carried out at each ON / OFF cycle of the compressor (in the example of figure 4 for all the four cycles considered there was no need for a total defrosting of the evaporator 12c). It has been found that with the operating mode according to the invention, the temperature of the food product TP contained in the refrigerator substantially corresponds to the average temperature of the refrigerator, with a difference between the maximum temperature in the cavity (TB) and minimum temperature (TA) , The so-called â € œstratificationâ € of temperature inside the cavity, of the order of 2.1 ° C (reference zone K in figure 4).

Questa  stratificazione  à ̈ notevolmente più bassa  rispetto  ad una metodologia  tradizionale di  sbrinamento  (figura 5)  in cui  lo sbrinamento stesso viene effettuato ad ogni ciclo ON/OFF del  compressore.  In questo caso  la temperatura media della cavità TM oscilla rispetto a quella del  prodotto (TP), ed il valore di stratificazione della temperatura Ã ̈ dell’ordine di 3,5°C.  This stratification is considerably lower than a traditional defrosting method (figure 5) in which the defrost itself is carried out at each ON / OFF cycle of the compressor. In this case, the average temperature of the cavity fluctuates with respect to that of the product (TP), and the stratification value of the temperature is in the order of 3.5 ° C.

Sebbene nella descrizione ci si sia limitati ad un frigorifero ad una sola cavità, Ã ̈ evidente che la  soluzione  tecnica  secondo  l’invenzione  può  essere  utilizzata  in  frigoriferi  aventi  più  cavità  a  temperature  diverse  fra  loro,  con  uno  o  più  evaporatori.  Inoltre  al  circuito  elettronico  di  controllo 14 possono essere collegati ulteriori  sensori di  temperatura  sia dell’evaporatore  sia  della cavità, senza per questo scostarsi dal procedimento descritto. In ogni caso con lo schema  semplificato  illustrato  in figura 1, e cioà ̈ con un minimo numero di sensori e con un algoritmo  molto semplice che non richiede un sofisticato sistema di controllo, Ã ̈ possibile ottenere ottimi  risultati  in termini di efficienza energetica dell’elettrodomestico e di puntualità nell’effettuare  di un ciclo completo di sbrinamento. Il procedimento secondo l’invenzione può essere adattato  anche a frigoriferi in cui lo sbrinamento Ã ̈ reso più rapido mediante l’utilizzo di una resistenza di  riscaldamento associata all’evaporatore.  Although in the description we have limited ourselves to a refrigerator with a single cavity, it is evident that the technical solution according to the invention can be used in refrigerators having several cavities at different temperatures, with one or more evaporators. Furthermore, further temperature sensors of both the evaporator and the cavity can be connected to the electronic control circuit 14, without departing from the described procedure. In any case, with the simplified scheme illustrated in figure 1, that is with a minimum number of sensors and with a very simple algorithm that does not require a sophisticated control system, it is possible to obtain excellent results in terms of energy efficiency of the appliance and punctuality in carrying out a complete defrost cycle. The process according to the invention can also be adapted to refrigerators in which defrosting is made faster by using a heating element associated with the evaporator.

 

Claims (10)

RIVENDICAZIONI  1. Procedimento per  il controllo dello sbrinamento di un evaporatore  (12c) posto  in una  cavità  (10a)  di  un  frigorifero  (10)  provvisto  di  un  circuiti  frigorifero  (12)  con  un  compressore (12a) il cui azionamento on/off fa variare la temperatura dell’evaporatore  (12c)  fra un  valore massimo  ed uno minimo  in  relazione  alla  temperatura desiderata  nella  cavità  (10a),  ed  in  cui  à ̈  previsto  l’uso  di  un  sensore  (16)  di  temperatura  dell’evaporatore  (12c) ed  in cui  il compressore  (12a) Ã ̈ disattivato  in modo  tale che  la  temperatura  dell’evaporatore  (12c)  raggiunga  un  valore  pari  alla  temperatura  di  sbrinamento, caratterizzato dal fatto che comprende le ulteriori fasi di valutare il tempo  di permanenza alla temperatura di sbrinamento e confrontarlo con un valore di soglia  predeterminato,  qualora  il  tempo  di  permanenza  sia  superiore  al  valore  di  soglia  predeterminato  mantenere  disattivato  il  compressore  (12a)  al  fine  di  consentire  un  completo  sbrinamento  dell’evaporatore  (12c)  e,  qualora  il  tempo  di  permanenza  sia  inferiore  al  valore di  soglia predeterminato,  riprendere  il normale  funzionamento del  compressore (12a).  CLAIMS 1. Procedure for controlling the defrosting of an evaporator (12c) placed in a cavity (10a) of a refrigerator (10) equipped with a refrigeration circuit (12) with a compressor (12a) whose on / off activation changes the evaporator temperature (12c) between a maximum and a minimum value in relation to the desired temperature in the cavity (10a), and in which the use of an evaporator temperature sensor (16) is envisaged (12c ) And in which the compressor (12a) is deactivated in such a way that the evaporator temperature (12c) reaches a value equal to the defrost temperature, characterized by the fact that it includes the further steps of evaluating the residence time at the temperature defrost and compare it with a predetermined threshold value, if the residence time is greater than the predetermined threshold value, keep the compressor off (12a) in order to allow complete defrosting of the evaporator (12c) and, if the residence time is less than the predetermined threshold value, resume normal compressor operation (12a). 2. Procedimento secondo la rivendicazione 1, in cui al superamento del valore di soglia del  tempo  di  permanenza  alla  temperatura  di  sbrinamento,  il  compressore  (12a)  viene  mantenuto  disattivato  sino  al  raggiungimento  di  una  predeterminata  temperatura  superiore a 0°C in modo da garantire uno sbrinamento completo dell’evaporatore (12c).  2. Process according to claim 1, wherein when the threshold value of the residence time at the defrost temperature is exceeded, the compressor (12a) is kept deactivated until a predetermined temperature higher than 0 ° C is reached so as to guarantee a complete defrosting of the evaporator (12c). 3. Procedimento secondo  la rivendicazione 2,  in cui detta  temperatura predeterminata Ã ̈  compresa tra 0,7 e 4,5°C.  3. Process according to claim 2, wherein said predetermined temperature is comprised between 0.7 and 4.5 ° C. 4. Procedimento  secondo  una  qualsiasi  delle  rivendicazioni  precedenti,  in  cui  il  compressore  (12a) Ã ̈ azionato  in modo  tale  che  la  temperatura di  sbrinamento venga  raggiunta solamente dopo un tempo predeterminato a partire dall’ultimo sbrinamento  ed in cui la temperatura dell’evaporatore (12c) viene fatta oscillare tra una temperatura  massima ed una temperatura minima entrambe inferiori a 0°C.  4. Process according to any one of the preceding claims, in which the compressor (12a) is operated in such a way that the defrost temperature is reached only after a predetermined time starting from the last defrost and in which the temperature of the evaporator (12c) is made to oscillate between a maximum temperature and a minimum temperature both below 0 ° C. 5. Procedimento secondo una qualsiasi delle rivendicazioni 1†3, in cui il compressore (12a)  à ̈ azionato in modo tale che la temperatura di sbrinamento Ã ̈ raggiunta ad ogni ciclo di  funzionamento del compressore (12a).  Process according to any one of claims 1 ... 3, wherein the compressor (12a) is operated in such a way that the defrost temperature is reached at each operating cycle of the compressor (12a). 6. Frigorifero comprendente una cavità provvista di un evaporatore (12c) facente parte di  un  circuito  refrigerante  (12)  con  un  compressore,  detto  frigorifero  comprendendo  un’unità  di  controllo  (14)  a  cui  à ̈  collegato  un  sensore  (16)  di  temperatura  dell’evaporatore, l’unità di controllo (14) essendo adatta a disattivare il compressore per  un tempo sufficiente affinchà ̈ la temperatura dell’evaporatore raggiunga la temperatura  di  sbrinamento,  caratterizzato  dal  fatto  che  detta  unità  di  controllo  (14)  à ̈  atta  a  misurare il tempo di permanenza dell’evaporatore alla temperatura di sbrinamento ed a  confrontare  detto  tempo  di  permanenza  con  un  valore  di  soglia  predeterminato  e,  qualora  detto  valore  misurato  superi  il  valore  di  soglia,  a  mantenere  disattivato  il  compressore    per  un  tempo  sufficiente  a  garantire  un’ulteriore  innalzamento  della  temperatura dell’evaporatore fino ad un valore massimo predeterminato.  6. Refrigerator comprising a cavity equipped with an evaporator (12c) forming part of a refrigerant circuit (12) with a compressor, said refrigerator comprising a control unit (14) to which a temperature sensor (16) is connected of the evaporator, the control unit (14) being suitable for deactivating the compressor for a time sufficient for the evaporator temperature to reach the defrost temperature, characterized by the fact that said control unit (14) is ̈ able to measure the evaporator residence time at the defrost temperature and to compare said residence time with a predetermined threshold value and, if said measured value exceeds the threshold value, to keep the compressor off for a sufficient time to ensure a further increase in the evaporator temperature up to a maximum value p redetermined. 7. Frigorifero  secondo  la  rivendicazione  6,  in  cui  l’unità  di  controllo  (14)  à ̈  adatta  a  garantire uno sbrinamento completo dell’evaporatore  (12c) al superamento del valore  di  soglia  del  tempo  di  permanenza  alla  temperatura  di  sbrinamento,  il  compressore  (12a)  essendo  mantenuto  disattivato  sino  al  raggiungimento  di  una  predeterminata  temperatura superiore a 0°C.  7. Refrigerator according to claim 6, in which the control unit (14) is suitable for guaranteeing a complete defrosting of the evaporator (12c) when the threshold value of the residence time at the defrost temperature is exceeded, the compressor (12a) being kept deactivated until a predetermined temperature above 0 ° C is reached. 8. Frigorifero  secondo  la  rivendicazione  7,    in  cui  detta  temperatura  predeterminata  à ̈  compresa tra 0,7 e 4,5°C.  8. Refrigerator according to claim 7, wherein said predetermined temperature is comprised between 0.7 and 4.5 ° C. 9. Frigorifero secondo una qualsiasi delle rivendicazioni 6†8, in cui l’unità di controllo (14) Ã ̈  adatta ad azionare il compressore (12a) in modo tale che la temperatura di sbrinamento  venga  raggiunta  solamente  dopo  un  tempo  predeterminato  a  partire  dall’ultimo  sbrinamento,  la  temperatura  dell’evaporatore  (12c)  essendo  fatta  oscillare  tra  una  temperatura massima ed una temperatura minima entrambe inferiori a 0°C.  9. Refrigerator according to any one of claims 6â € 8, wherein the control unit (14) is suitable for activating the compressor (12a) in such a way that the defrosting temperature is reached only after a predetermined time starting since the last defrost, the evaporator temperature (12c) being made to oscillate between a maximum and a minimum temperature, both below 0 ° C. 10. Frigorifero secondo una qualsiasi delle rivendicazioni 6†8, in cui l’unità di controllo (14) Ã ̈  adatta  ad  azionare    il  compressore  (12a)  in  modo  tale  che  la  temperatura  di  sbrinamento sia raggiunta ad ogni ciclo di funzionamento del compressore (12a). 10. Refrigerator according to any one of claims 6â € 8, wherein the control unit (14) is suitable for operating the compressor (12a) in such a way that the defrosting temperature is reached at each operating cycle of the compressor (12a).
IT000031A 2011-11-17 2011-11-17 PROCEDURE FOR THE DEFROSTING OF AN EVAPORATOR AND REFRIGERATOR SUITABLE FOR IMPLEMENTING THIS PROCEDURE ITVA20110031A1 (en)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4156350A (en) * 1977-12-27 1979-05-29 General Electric Company Refrigeration apparatus demand defrost control system and method
GB2100031A (en) * 1981-04-03 1982-12-15 Foster Refrigerator Uk Ltd Electrical control circuit for refrigerators and freezers
US5228300A (en) * 1991-06-07 1993-07-20 Samsung Electronics Co., Ltd. Automatic operation control method of a refrigerator
US20080092569A1 (en) * 2006-10-20 2008-04-24 Doberstein Andrew J Cooling unit with multi-parameter defrost control

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4156350A (en) * 1977-12-27 1979-05-29 General Electric Company Refrigeration apparatus demand defrost control system and method
GB2100031A (en) * 1981-04-03 1982-12-15 Foster Refrigerator Uk Ltd Electrical control circuit for refrigerators and freezers
US5228300A (en) * 1991-06-07 1993-07-20 Samsung Electronics Co., Ltd. Automatic operation control method of a refrigerator
US20080092569A1 (en) * 2006-10-20 2008-04-24 Doberstein Andrew J Cooling unit with multi-parameter defrost control

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