EP0563724B1 - Procédé et dispositif pour l'évaluation de la formation de givre sur un évaporateur de réfrigération, en particulier du type à circulation forcée d'air - Google Patents

Procédé et dispositif pour l'évaluation de la formation de givre sur un évaporateur de réfrigération, en particulier du type à circulation forcée d'air Download PDF

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Publication number
EP0563724B1
EP0563724B1 EP93104634A EP93104634A EP0563724B1 EP 0563724 B1 EP0563724 B1 EP 0563724B1 EP 93104634 A EP93104634 A EP 93104634A EP 93104634 A EP93104634 A EP 93104634A EP 0563724 B1 EP0563724 B1 EP 0563724B1
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EP
European Patent Office
Prior art keywords
motor
evaporator
fan
constant
air
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP93104634A
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German (de)
English (en)
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EP0563724A1 (fr
Inventor
Daniele C/O Whirlpool Italia S.R.L. Turetta
Adriano c/o Whirlpool Italia s.r.l. Scaburri
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Whirlpool Europe BV
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Whirlpool Europe BV
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Publication date
Application filed by Whirlpool Europe BV filed Critical Whirlpool Europe BV
Publication of EP0563724A1 publication Critical patent/EP0563724A1/fr
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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
    • F25D21/00—Defrosting; Preventing frosting; Removing condensed or defrost water
    • F25D21/02—Detecting the presence of frost or condensate

Definitions

  • This invention relates to a method for evaluating frost formation on an evaporator in a refrigerator, in particular of the forced-air circulation type and comprising a cabinet containing one or more temperature-controlled compartments provided with their own access doors and arranged to contain food during its preservation, there being provided at least one heating element which when activated defrosts the evaporator, and a fan driven by an electric motor for circulating air through the evaporator and for ventilating the compartment or compartments via ducts provided within said cabinet, said fan, to achieve said circulation, cooperating with a conveying member to direct the air circulating within said compartment or compartments onto the evaporator so that the Air is cooled.
  • Said defrosting is effected in various ways.
  • the evaporator may be defrosted automatically after a fixed period of operation of the usual refrigeration circuit of the refrigerator (or of the known compressor of this circuit).
  • this method of defrosting does not take account of whether it is really necessary to remove frost from the evaporator at that time, hence defrosting may take place when there is no real need for it (with obvious disadvantages in terms of refrigerator operation).
  • said methods and devices do not allow accurate and reliable measurement of the frost thickness on the evaporator, and are able only to sense whether a layer is present on a given portion of it. Consequently, operation of the heating element associated with the evaporator, based on the sensing of frost on it, may sometimes be unnecessary, so negatively affecting the refrigerator performance.
  • An object of the present invention is to provide a method for sensing the presence of frost on the evaporator by which this latter is defrosted only if it is covered with a layer of frost to the extent of changing its heat transfer characteristics.
  • a further object is to provide a method of the aforesaid type which is of low implementation cost and which enables the evaporator defrosting process to be optimized.
  • a further object of the invention is to provide a device for evaluating the thickness of frost on an evaporator which is of simple construction, of reliable use and operation, and is able to activate the heating element associated with the evaporator only when on the surface of this latter there is a quantity of frost present such as to change its heat transfer characteristics.
  • Said method is implemented by a device applied to a refrigerator of the aforesaid type, characterised by comprising switch means connected into a line powering the motor of the fan, sensor means for sensing an operating parameter of the motor and generating a signal relative to the fan operating condition, said signal being fed to comparison and control means which compare it with a reference signal and on the basis of this comparison act on the switch means to change the fan operating conditions, and on the heating element to activate it and hence defrost the evaporator.
  • a refrigerator for example a domestic refrigerator
  • a refrigerator for example a domestic refrigerator
  • a known control member 5 such as a static switch controlled by a usual control unit, not shown, connected to a known timer which controls the operation of the refrigerator.
  • the fan 3 is contained in a compartment 100 provided in the cabinet 1A of the refrigerator, in correspondence with an evaporator 102, and can also feed air through a duct 103 if the refrigerator is of the type comprising several superposed compartments, said duct terminating in at least one of these compartments.
  • the fan also feeds air directly into the compartment 100 via an aperture 105 provided in correspondence with the evaporator 102. In proximity to this latter there is also a usual air conveying member 106 through which air can be drawn from the compartment 100 and onto the evaporator via an aperture 107.
  • the evaporator comprises a body 110 provided with fins 111 in known manner.
  • the motor 2 of the fan 3 is connected to the control member 5 by a return line 4A, said control member being powered in known manner by mains voltage V E .
  • a feedback branch 6 connects the member 5 to an integrator member or circuit 8 connected by electrical branches 9 and 10 to the ends 11 and 12 of the motor 3.
  • the integrator member or circuit measures the feed voltage across the ends 11 and 12 of the motor 3 and generates in the feedback branch a control signal V A which enables the member 5 to maintain the feed voltage of the motor 3 constant in known manner.
  • a tachometer dynamo 15 (or a control circuit comprising such a dynamo) measures the r.p.m. of the motor 2.
  • the dynamo 15 is connected to a digital/analog converter 16 connected to a non-inverting input 17 of any known comparator circuit or member 18.
  • the inverting input 19 of the circuit or member 18 receives a reference signal V E corresponding to a very thin layer of frost on the evaporator, ie unable to significantly impede the air flow traversing the evaporator 102.
  • the output 20 of said circuit 18 is connected to a usual heating element 21 located in correspondence with the evaporator 102.
  • Said comparator circuit or member 18 also controls the opening of a switch 23 in the line 4, for example via a usual bistable element (not shown) or an analogous relay 28 connected to its output 20.
  • the switch 23 is normally closed during normal operation of the refrigerator.
  • the member 5 controls the operation of the motor 2 in any known manner. As stated, via the integrator circuit 8 the member 5 controls the power supply to the motor 2 such that it is operated at constant voltage.
  • This member is also connected by an electrical branch 29 to a usual relay 30 arranged to control a switch 31 in the output 20 of the circuit 18 towards the heating element 21 (as shown in Figure 3).
  • frost forms on the evaporator and with the passage of time reaches a significant thickness such as to reduce the normal flow of air along the evaporator fins 111. This changes the fan r.p.m., which tends to "rotate idly". This increase is sensed by the tachometer 15.
  • the tachometer During normal refrigerator operation with no frost on the evaporator 102, the tachometer generates a signal V B (digital) of a value only slightly different from or lower than the signal V E .
  • V C analog or digital
  • the member 5 senses the opening of the switch 23 in known manner and acts (directly or indirectly) on the usual compressor (not shown) of the refrigeration circuit of which the evaporator 102 forms part, and halts it. The operation of the refrigerator consequently ceases.
  • the member 5 acts on the relay 30, which opens tile switch 31 (normally closed). This interrupts the operation of the heating element 21.
  • the relay 28 closes the switch 23 in known manner.
  • the member 5 can therefore again control the operation of the fan 3 and reactivate the compressor to return the refrigerator to operation.
  • frost sensor senses that there is no longer frost on the evaporator.
  • Modifications are however possible, such as the tachometer not generating a digital signal but instead directly generating an analog signal which is compared continuously by the circuit or member 18 with the reference signal (also analog in this case).
  • This latter can be fixed or variable, and be set by usual electrical members such as a trimmer or other known member.
  • the member 5 can also be a usual microprocessor circuit and effect the comparison between the signals V B and V E . This can be done either continuously during the entire period of operation of the refrigerator 1 or cyclically at particular times.
  • FIG 4 in which parts corresponding to those of Figure 3 are indicated by the same reference numerals, shows a further embodiment of the invention.
  • the feedback branch (by which the member 5 controls the operation of the motor 2 at a constant r.p.m.) is connected directly to the digital/analog converter 16 or to the tachometer 15 if this generates an analog signal V B or if the member 5 is able to operate directly on a digital signal.
  • a shunt resistor 40 is connected into the return branch 4A from the motor 2 to the member 5 in series with this motor, and has its ends 41, 42 connected to electrical branches 43, 44 leading to the integrator circuit 8, and to branches 45, 56 leading to a known current member or sensor 47.
  • the circuit 8 and the sensor 47 are connected by electrical branches 48, 49 respectively, to a usual multiplier 50. These branches carry signals corresponding to the voltage and to the current absorbed by the motor 2 respectively.
  • the multiplier 50 generates in its output branch 51 a signal V D proportional to the power absorbed from the mains by the motor 2 during its operation.
  • the branch 51 terminates at the non-inverting input of the circuit or member 18.
  • the signal V C is substantially close to or less than the signal V E (in value).
  • FIG. 5 shows a further embodiment of the invention.
  • parts corresponding to those of the previously described figures are indicated by the same reference numerals.
  • the operation of the motor 2 is again controlled at constant r.p.m. by the tachometer dynamo 15.
  • Frost formation is however evaluated via the integrator circuit 8 or via the variation in the feed voltage of the motor 2 as measured by the circuit 8.
  • circuit 18 acts in the described manner, to halt the motor 2 and activate the heating element 21.
  • the motor 2 is again operated and the heating element 21 switched off (as already described).
  • FIG. 6 shows a further embodiment of the invention.
  • parts corresponding to those of the previously described figures are indicated by the same reference numerals.

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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)

Claims (10)

  1. Procédé pour évaluer la formation de givre sur un évaporateur (102) dans un réfrigérateur (1), en particulier du type à circulation forcée d'air, et comprenant une carrosserie (1A) qui contient un ou plusieurs compartiments (100) à température contrôlée, pourvus de leurs propres portes d'accès et agencés pour contenir des aliments pendant leur conservation, au moins un élément de chauffage (21) étant prévu, lequel dégivre l'évaporateur lorsqu'il est activé, et un ventilateur (3) entraîné par un moteur électrique (2) pour faire circuler de l'air à travers l'évaporateur et pour ventiler le(s) compartiment(s) via des conduits prévus dans ladite carrosserie, dans lequel pour assurer ladite circulation, ledit ventilateur coopère avec un élément de transport pour diriger l'air qui circule à l'intérieur dudit (desdits) compartiment(s) sur l'évaporateur de façon que l'air soit refroidi, ledit procédé étant caractérisé par le fait qu'on mesure la variation d'un paramètre de fonctionnement du moteur (2) qui entraîne le ventilateur (3).
  2. Procédé selon la revendication 1, caractérisé en ce que le paramètre de fonctionnement mesuré est la tension absorbée depuis le réseau par le moteur (2) lorsqu'il fonctionne à vitesse de rotation constante.
  3. Procédé selon la revendication 1, caractérisé en ce que le paramètre de fonctionnement mesuré est le courant absorbé depuis le réseau par le moteur (2) lorsqu'il fonctionne à vitesse de rotation constante.
  4. Procédé selon la revendication 1, caractérisé en ce que le paramètre de fonctionnement mesuré est la puissance absorbée depuis le réseau par le moteur (2) lorsqu'il fonctionne à une vitesse de rotation constante.
  5. Procédé selon la revendication 1, caractérisé en ce que le paramètre de fonctionnement mesuré est la vitesse de rotation du moteur (2) lorsqu'il fonctionne sous tension constante.
  6. Dispositif pour évaluer la formation de givre sur un évaporateur (102) dans un réfrigérateur (1), en particulier du type à circulation forcée d'air et comprenant une carrosserie qui contient un ou plusieurs compartiments (100) à température commandée, pourvus de leurs propres portes d'accès et agencés pour contenir des aliments pendant leur conservation, au moins un élément de chauffage (21) étant prévu, lequel dégivre l'évaporateur lorsqu'il est activé, et un ventilateur (3) entraîné par un moteur électrique (2) pour faire circuler l'air à travers l'évaporateur et pour ventiler le(s) compartiment(s) via des conduits prévus dans ladite carrosserie, et dans lequel pour assurer ladite circulation, ledit ventilateur coopère avec un élément de transport pour diriger l'air qui circule dans ledit (lesdits) compartiment(s) sur l'évaporateur de sorte que l'air soit refroidi, caractérisé en ce qu'il comprend des moyens de commutation (23) connectés à une ligne (4) qui alimente le moteur (2) du ventilateur (3), des moyens de détection (15, 8, 47, 50) pour détecter un paramètre de fonctionnement du moteur (2) et pour produire un signal (VB, VD, VG, VH) concernant la condition de fonctionnement du ventilateur, ledit signal étant alimenté à des moyens de comparaison et de commande (18) qui le comparent à un signal de référence (VE) et qui sont adaptés pour agir, sur la base de cette comparaison, sur les moyens de commutation (23) pour changer les conditions de fonctionnement du ventilateur (3), et sur l'élément de chauffage (21) pour activer celui-ci pour assurer le dégivrage de l'évaporateur (102).
  7. Dispositif selon la revendication 6, caractérisé en ce que le moteur (2) du ventilateur fonctionne sous tension constante, et en ce que les moyens de détection sont une dynamo tachymétrique (15).
  8. Dispositif selon la revendication 6, caractérisé en ce que le moteur (2) du ventilateur fonctionne à vitesse de rotation constante, et en ce que les moyens de détection sont un circuit intégré (8).
  9. Dispositif selon la revendication 6, caractérisé en ce que le moteur (2) du ventilateur fonctionne à vitesse de rotation constante, ledit moteur étant du type à haute efficacité, et en ce que les moyens de détection sont un élément de mesure de courant (47) connecté aux bornes (41, 42) d'une résistance (40) connectée en série avec ledit moteur (2).
  10. Dispositif selon la revendication 6, caractérisé en ce que le moteur (2) du ventilateur fonctionne à vitesse de rotation constante, et en ce que les moyens de détection sont un élément multiplicateur (50) connecté à un circuit intégrateur (8) qui mesure la tension absorbée depuis le réseau par le moteur (2), et à un élément de mesure de courant (47) qui mesure le courant absorbé depuis le réseau par le moteur (2), ledit élément multiplicateur (50) produisant un signal (VD) alimenté aux moyens de comparaison et de commande (18) et correspondant à la puissance absorbée depuis le réseau par ledit moteur (2).
EP93104634A 1992-03-30 1993-03-22 Procédé et dispositif pour l'évaluation de la formation de givre sur un évaporateur de réfrigération, en particulier du type à circulation forcée d'air Expired - Lifetime EP0563724B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ITMI920755 1992-03-30
ITMI920755A IT1254854B (it) 1992-03-30 1992-03-30 Metodo e dispositivo per rilevare la formazione di brina su un evaporatore di un refrigeratore, in particolare del tipo a circolazione forzata d'aria

Publications (2)

Publication Number Publication Date
EP0563724A1 EP0563724A1 (fr) 1993-10-06
EP0563724B1 true EP0563724B1 (fr) 1996-09-18

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EP93104634A Expired - Lifetime EP0563724B1 (fr) 1992-03-30 1993-03-22 Procédé et dispositif pour l'évaluation de la formation de givre sur un évaporateur de réfrigération, en particulier du type à circulation forcée d'air

Country Status (3)

Country Link
EP (1) EP0563724B1 (fr)
DE (1) DE69304761T2 (fr)
IT (1) IT1254854B (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP4043251A1 (fr) 2021-02-15 2022-08-17 Volkswagen Ag Procédé de démarrage d'un processus de dégivrage d'un échangeur de chaleur d'une pompe à chaleur d'un véhicule automobile
EP4043252A1 (fr) 2021-02-15 2022-08-17 Volkswagen Ag Procédé de démarrage d'un processus de dégivrage d'un échangeur de chaleur d'une pompe à chaleur d'un véhicule automobile

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR0134934B1 (ko) * 1994-09-15 1998-04-28 구자홍 간냉식 냉장고의 제상장치
DE10019905C2 (de) 2000-04-20 2002-04-25 Bosch Gmbh Robert Verfahren und Vorrichtung zur Erkennung der Vereisungsgefahr bei zur Tankleckdiagnose bei Kraftfahrzeugen eingesetzten Pumpen
DE10057006C1 (de) * 2000-11-17 2002-05-23 Friedhelm Meyer Verfahren und Vorrichtung zum Betreiben von Klima- und Kälteanlagen
DE10116693A1 (de) 2001-04-04 2002-10-17 Bosch Gmbh Robert Beheizbare Tankleckdiagnoseeinheit insbesondere für Kraftfahrzeuge
DE10315523A1 (de) * 2003-04-04 2004-10-14 BSH Bosch und Siemens Hausgeräte GmbH Kältegerät mit adaptiver Abtauautomatik und Abtauverfahren dafür
CN113237684B (zh) * 2021-05-20 2022-05-10 长虹美菱股份有限公司 一种评价冰箱冷冻室结霜程度的试验方法

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3728867A (en) * 1971-04-29 1973-04-24 Ranco Inc Defrost control system
GB2033582B (en) * 1978-10-31 1983-05-11 Dart Ausschank Rat Tech Liquid metering method and device
US4806833A (en) * 1986-09-22 1989-02-21 General Electric Company System for conditioning air, method of operating such, and circuit

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP4043251A1 (fr) 2021-02-15 2022-08-17 Volkswagen Ag Procédé de démarrage d'un processus de dégivrage d'un échangeur de chaleur d'une pompe à chaleur d'un véhicule automobile
EP4043252A1 (fr) 2021-02-15 2022-08-17 Volkswagen Ag Procédé de démarrage d'un processus de dégivrage d'un échangeur de chaleur d'une pompe à chaleur d'un véhicule automobile
DE102021201380A1 (de) 2021-02-15 2022-08-18 Volkswagen Aktiengesellschaft Verfahren zum Einleiten eines Abtauprozesses eines Wärmeübertragers einer Wärmepumpe eines Kraftfahrzeugs
DE102021201377A1 (de) 2021-02-15 2022-08-18 Volkswagen Aktiengesellschaft Verfahren zum Einleiten eines Abtauprozesses eines Wärmeübertragers einer Wärmepumpe eines Kraftfahrzeuges

Also Published As

Publication number Publication date
ITMI920755A0 (it) 1992-03-30
IT1254854B (it) 1995-10-11
DE69304761D1 (de) 1996-10-24
ITMI920755A1 (it) 1993-09-30
DE69304761T2 (de) 1997-03-20
EP0563724A1 (fr) 1993-10-06

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