EP2722619A1 - Réfrigérateur no-frost - Google Patents

Réfrigérateur no-frost Download PDF

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Publication number
EP2722619A1
EP2722619A1 EP13189431.3A EP13189431A EP2722619A1 EP 2722619 A1 EP2722619 A1 EP 2722619A1 EP 13189431 A EP13189431 A EP 13189431A EP 2722619 A1 EP2722619 A1 EP 2722619A1
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EP
European Patent Office
Prior art keywords
evaporator
duct
refrigerating appliance
cell
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.)
Withdrawn
Application number
EP13189431.3A
Other languages
German (de)
English (en)
Inventor
Alessandro Pizzutti
Giorgio Sabatini
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 EMEA SpA
Original Assignee
Indesit Co SpA
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Indesit Co SpA filed Critical Indesit Co SpA
Publication of EP2722619A1 publication Critical patent/EP2722619A1/fr
Withdrawn legal-status Critical Current

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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
    • F25D21/002—Defroster control
    • F25D21/006—Defroster control with electronic control circuits

Definitions

  • the present invention relates to a refrigerating appliance, in particular for household use.
  • the present invention is applicable, in particular, to refrigerating appliances of the "no-frost" type.
  • No-frost refrigerating appliances for household use have now become widespread, which are refrigerating appliances wherein refrigeration of one or more cells adapted to contain foods occurs through circulation of cold air.
  • the evaporator is positioned in a volume which is separate from the cell(s), and circulation of cooled air in contact with the evaporator occurs through suitable circulation means, typically comprising ducts and one or more fans. In this way, it is possible to prevent the formation of ice or frost on the walls of the food-containing cell.
  • a no-frost refrigerating appliance is described in document KR20100009676A published on 29-1-2010, filed on 21-7-2008 under application number KR20080070415 .
  • Said document relates to a refrigerating appliance comprising a cell, an evaporator and two humidity sensors, one measuring the air directed towards the evaporator and the other measuring the air discharged downstream of the evaporator.
  • the control means of the described refrigerating appliance operate on the basis of the humidity variation between the two readings, controlling the evaporator defrosting operation accordingly.
  • the above-described solution suffers from a number of drawbacks: in general, the readings of humidity sensors are particularly subject to disturbances; therefore, when controlling the defrosting operation as proposed by the above-mentioned document, i.e. on the basis of the humidity variation measured by the two sensors, the latter may be affected by disturbances and lead to the risk that the control of the evaporator defrosting operation will be neither optimal nor efficient.
  • the object of the present invention is to provide a refrigerating appliance capable of solving some of the problems suffered by the prior art.
  • One idea at the basis of the present invention is to provide a refrigerating appliance comprising at least one refrigerated cell, cooling means comprising at least one evaporator, at least one first duct that puts the cell in fluidic communication with an external surface of the evaporator for feeding air to be cooled from the cell to the evaporator, and further comprising a second duct that puts the external surface of the evaporator in fluidic communication with the cell for feeding cooled air from the evaporator to the cell, and further comprising air circulation means for circulating air within the first duct and the second duct.
  • the refrigerating appliance further comprises defrosting means adapted to remove ice and/ or frost accumulated on the external surface of the evaporator, and control means for controlling the operation thereof.
  • the refrigerating appliance further comprises a temperature sensor and a humidity sensor, which are adapted to measure the temperature and humidity, respectively, of the air flowing in the first duct, and which are operationally connected to the control means, so that the operation of the defrosting means can be adjusted depending on the readings of the temperature sensor and humidity sensor.
  • control means comprise computing means adapted to estimate the quantity of ice and/or frost deposited on the surface of the evaporator, through acquisition, at subsequent time instants, of the readings of the temperature and humidity sensors, and through a parameter related to the volumetric flow rate of the air within the duct.
  • the parameter that estimates the volumetric flow rate depends on the cross-section of the duct and on the pressure head of the air circulation means that allow recirculation of cooled air from the cell to the evaporator.
  • the parameter that estimates the volumetric flow rate is further computed on the basis of the time of operation of the air circulation means, which may comprise a fan and/or a damper.
  • control means are adapted to turn on the defrosting means based on the estimate provided by the computing means, and to turn off the defrosting means after a predetermined time.
  • control means are further adapted to turn on/off the defrosting means, the operating time of the defrosting means being controlled based on the estimate provided by the computing means.
  • Said refrigerating appliance therefore, reduces the waste of electricity and keeps the evaporator frost-free to ensure the utmost cooling efficiency, while keeping the power consumption of the defrosting means to a minimum.
  • Figure 1 schematically shows a cross-section of a refrigerating appliance 1 of the "no-frost" type according to the present invention.
  • the refrigerating appliance 1 comprises a cell 2 adapted to contain fresh foods, accessible through a door 3.
  • the refrigerating appliance 1 further comprises a cell 2b adapted to contain frozen foods, accessible through a respective door 3b. Therefore, the embodiment described herein relates to a type of refrigerating appliance which is commonly referred to as "double-door".
  • the cell 2 comprises a plurality of shelves 4 or drawers 5 adapted to contain the objects to be refrigerated, typically fresh foods.
  • the refrigerating appliance 1 further comprises known cooling means, of which only a few components specifically involved in the present invention will be illustrated in detail herein. Wherever no explicit reference to particular elements is made, the refrigerating appliance 1 will have to be understood as comprising all known means which are necessary for the proper operation of the appliance itself, in accordance with the state of the art.
  • the refrigerating appliance 1 comprises an evaporator 6 in which a refrigerated fluid circulates, the evaporator 6 having such a shape and characteristics as to interact with an air flow lapping its external surfaces for the purpose of cooling the air, which in turn will cool the cell 2.
  • the evaporator 6 is connected to further elements (not shown in Figure 1 ) that create a refrigeration cycle in accordance with the teachings of the prior art.
  • the air is taken from the inside of the cell 2 and is directed, through a first duct 7, towards the evaporator 6. While passing through the evaporator 6, the air is cooled by contact with the external surfaces thereof, and then re-enters the cell 2 via a second duct 8, which comprises a respective plurality of apertures 9 through which cooled air exits and cools the foods in the cell.
  • a second duct 8 which comprises a respective plurality of apertures 9 through which cooled air exits and cools the foods in the cell.
  • Various ducting solutions are available in the art which may differ from the one shown herein, e.g. comprising a plurality of ducts 7 and/or 8, depending on specific design choices.
  • the path followed by the air in the ducts is shown by arrows in Figure 1 .
  • the air is moved in the ducts by suitable air circulation means, which typically comprise at least one fan 10 that gives the air flow a sufficient pressure head for it to follow the path in the ducts.
  • the air circulation means 10 are adapted to circulate cooled air also within the cell 2b for frozen foods, which is separated by a bulkhead having an aperture 9b and also comprising a further (separate) duct 7b for feeding air to be cooled, coming from the cell 2b, towards the evaporator 6.
  • the refrigerating appliance comprises a selective air circulation element 10b, typically referred to as "damper".
  • Said element 10b is adapted to adjust, by reducing or preventing it, the air flow within the duct 8.
  • damper 10b is therefore particularly appropriate when combined with the technical features of a refrigerating appliance such as the refrigerating appliance 1 described herein, which comprises two cells 2 and 2b to be selectively cooled to different temperatures by means of a single evaporator 6.
  • the damper 10b allows to adjust and/or partialize the flow of cooled air delivered to the cell 2 for fresh foods, thereby ensuring an effective operation of both the refrigerator and freezer parts of the refrigerating appliance.
  • the damper 10b may operate in accordance with the teachings of the prior art, typically based on the temperature detected in the cell 2.
  • a refrigerator like the one described above is called "no-frost" because the configuration of the evaporator 6, and in particular of the ducts 7 and 8, along with the duct 7b and the aperture 9b, prevents the humidity which is present inside the cell 2 from freezing on the shelves 4, in the drawers 5 or on the walls of the cell 2 itself.
  • Air-borne humidity will still tend to condensate and freeze instantaneously, thus forming a layer of frost on the external surfaces of the evaporator 6 itself, to which it is sent via the duct 7; in operating conditions, in fact, said surfaces have a temperature which is typically in the range of -30°C to -35°C, also when the refrigerating appliance 1 is operating as a freezer.
  • the air that laps the external surfaces of the evaporator 6 runs into conditions that cause it to almost completely lose its moisture content, the air that recirculates in the duct 8 when the damper 10b is open and exits through the outlets 9 is dry air, i.e. it contains no residual water vapour or only a negligible quantity thereof.
  • a no-frost refrigerator as aforesaid, the moisture content of the air condenses and freezes on the evaporator 6.
  • the layer of ice and/or frost accumulates on the evaporator 6 and grows thicker and thicker, because additional ambient humidity enters the cell 2 every time the door 3 is opened. In the long run, after many hours of operation, the quantity of ice and/or frost accumulated on the evaporator 6 will become considerable, thus worsening the thermal exchange between the evaporator 6 itself and the air in the duct 7.
  • the defrosting means 6b typically comprise a heatable element such as an electric resistor, and preferably comprise a suitable hydraulic circuit (not shown) allowing the thawed ice and/or frost previously present on the evaporator to be drained away as water.
  • the operation of the defrosting means 6b is appropriately controlled in a way that will be described more in detail below. In general, it is appropriate to provide that, when the defrosting means 6b are in operation, e.g. heating the evaporator 6, the air circulation means 10 are inactive, so that no air will flow through the ducts and the cells 2 or 2b, which air would otherwise be heated, not cooled.
  • the refrigerating appliance 1 comprises suitable control means and sensors.
  • the refrigerating appliance 1 comprises a temperature sensor 11 and a humidity sensor 12, which are adapted to measure the temperature and the relative humidity, respectively, of the air flowing in the first duct 7.
  • the humidity sensor 12 and the temperature sensor 11 are positioned in that portion of the duct 7 which is closest to the cell 2.
  • the temperature sensor 11 and the humidity sensor 12 are integrated into a single sensing device, so as to reduce their dimensions and cost.
  • the refrigerating appliance 1 comprises a separation grid 13 between the cell 2 and the first duct 7, and the humidity sensor 12 and the temperature sensor 11 are positioned immediately downstream of the separation grid 13; in fact, this is the most advantageous position for an accurate reading of the properties of the air flow.
  • the temperature sensor 11 is also adapted to measure a temperature representative of the cell 2 as a whole, for monitoring the operation of the refrigerating appliance 1. In fact, said temperature sensor 11 can detect, in particular also when the air circulation means 10 are inactive, any temperature variations due to the placing of warm foods into the cell 2 or to the opening of the door 3.
  • the temperature sensor 11 it is possible to avoid using any further temperature sensors in the cell 2, thus reducing the cost and simplifying the construction of the refrigerating appliance 1.
  • This arrangement of the temperature sensor also offers the advantage that a forced air flow is obtained along the duct 7; in this way, the temperature sensor 11 is less susceptible to the placing of foods into the cell 2, and the air flow near the temperature sensor 11 cannot be hindered by bulky food or be affected by the local temperature of the foods themselves, thus improving the reading by the temperature sensor 11.
  • the temperature sensor 11 can therefore be used for controlling the operation of the cooling means of the appliance.
  • the control means of the refrigerating appliance 1 further comprise a plurality of sensors, control units and electronic devices according to the prior art, which for brevity's sake will not be described in detail below.
  • control means 14 are adapted to adjust the operation of the defrosting means 6b, to which they are operationally connected.
  • the control means 14 are adapted to selectively supply power to the electric resistors of the defrosting means 6b, thereby causing them to only heat up when necessary, in accordance with the particular logic of the control means 14.
  • the temperature sensor 11 and the humidity sensor 12 are operationally connected to the control means 14 via suitable electric and/or electronic connections of a known nature (not shown in the drawing), whether analog or digital.
  • the control means 14 utilize the readings taken by said sensors 11 and 12 to adjust the operation of the defrosting means 6b.
  • control means 14 comprise computing means, such as a processor, which can estimate the efficiency of the evaporator 6, which is essentially correlated to the quantity of ice and/or frost deposited on the surface thereof, by acquiring a plurality of readings via the temperature sensor 11 and the humidity sensor 12; such readings are taken at subsequent time instants during the operation of the refrigerating appliance 1.
  • computing means such as a processor, which can estimate the efficiency of the evaporator 6, which is essentially correlated to the quantity of ice and/or frost deposited on the surface thereof, by acquiring a plurality of readings via the temperature sensor 11 and the humidity sensor 12; such readings are taken at subsequent time instants during the operation of the refrigerating appliance 1.
  • the computing means use a parameter that estimates the volumetric flow rate of the air within the first duct 7 in combination with the relative humidity and temperature information to estimate the mass flow rate of the water borne by the air flowing in the duct 7 and directed towards the evaporator 6.
  • the sensors 11 and 12 measure the temperature and humidity of the air in the duct 7, it is possible to derive the moisture/water/steam content thereof; the volumetric flow rate, in particular the average volumetric flow rate, of the air within the duct 7 being known instant by instant, it is possible to estimate the mass flow rate of the water directed towards the evaporator 6.
  • the instantaneous volumetric flow rate essentially depends on the cross-section of the duct 7 and on the pressure head provided by the air circulation means 10, in accordance with known criteria of fluid dynamics. This can be complemented by the intervention of the damper 10b, when it throttles the duct 8 that feeds cooled air back into the cell 2.
  • the computing means are therefore adapted to estimate the average volumetric flow rate in the duct 7 within a time interval by taking into account the above-mentioned information.
  • the computing means can estimate the evolution over time of the deposit of ice and/or frost on the evaporator 6.
  • the temperature-dependent characteristics of the humid air are preferably stored into a suitable memory of the control means 14, thus representing a psychrometric chart according to the prior art, which the computing means will use in operation to make the calculations necessary for determining the corresponding quantity of frost.
  • the computing means can calculate the time necessary for a predetermined quantity of ice and/or frost to deposit on the evaporator 6, so that the defrosting means 6b can be turned on for a suitable time that will ensure the removal of said predetermined quantity of ice and/or frost.
  • the average volumetric flow rate is computed on the basis of the operating time of the air circulation means 10 and/or of the damper 10b.
  • the air circulation means 10 for example, will be activated when the cooling circuit that cools the evaporator comes on.
  • the damper 10b instead, as aforesaid, will be turned on in accordance with specific control logics of the refrigerating appliance.
  • the control means 14 will turn on the defrosting means 6b when the estimate of the quantity of ice and/or frost made by the computing means reaches a predetermined value (e.g. when the weight of the ice and/or frost reaches a value of 280 g); the control means 14 will then turn off the defrosting means 6b after a predetermined time, e.g. a time that allows the electric resistors to thaw all the ice and/or frost which is present on the evaporator 6.
  • the control means 15 are further adapted to turn on the defrosting means 6b after a predetermined time, without necessarily waiting for a predetermined quantity of ice and/or frost to deposit on the evaporator 6.
  • control means 14 will adjust the operation of the defrosting means 6b by controlling their on time, which will be computed by the computing means based on the estimate of the quantity of ice and/or frost deposited on the evaporator, in accordance with selected criteria.
  • the defrosting means 6b are turned on for a predetermined time when a limit quantity of ice and/or frost is reached, and also that the defrosting means 6b are turned on for a shorter time at predetermined intervals, e.g. 24 hours after the last defrosting operation, in order to appropriately thaw the ice and/or frost deposit on the evaporator 6.
  • the evaporator 6 can always be kept at its maximum efficiency, ensuring an optimal cooling of the refrigerator and reducing the waste of electricity.
  • the present invention has been described herein with reference to a refrigerating appliance such as a double-door refrigerator. It is clear that the teachings of the present invention can also be adapted, through appropriate technical changes, to single-cell refrigerators or combined refrigerators comprising cells for frozen foods and/or other types of cells for preserving any kind of contents.

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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)
  • Cold Air Circulating Systems And Constructional Details In Refrigerators (AREA)
  • Devices That Are Associated With Refrigeration Equipment (AREA)
EP13189431.3A 2012-10-19 2013-10-18 Réfrigérateur no-frost Withdrawn EP2722619A1 (fr)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
IT000923A ITTO20120923A1 (it) 2012-10-19 2012-10-19 Apparecchio refrigerante no frost

Publications (1)

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EP2722619A1 true EP2722619A1 (fr) 2014-04-23

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IT (1) ITTO20120923A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3764032A4 (fr) * 2018-03-08 2021-12-01 LG Electronics Inc. Réfrigérateur
EP4194784A4 (fr) * 2020-08-06 2024-07-24 Lg Electronics Inc Réfrigérateur

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2000274916A (ja) * 1999-03-26 2000-10-06 Sanyo Electric Co Ltd 冷却貯蔵庫
JP2009121803A (ja) * 2007-10-25 2009-06-04 Sharp Corp 冷蔵庫
KR20100009676A (ko) 2008-07-21 2010-01-29 삼성전자주식회사 냉장고 및 그 제어방법

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2000274916A (ja) * 1999-03-26 2000-10-06 Sanyo Electric Co Ltd 冷却貯蔵庫
JP2009121803A (ja) * 2007-10-25 2009-06-04 Sharp Corp 冷蔵庫
KR20100009676A (ko) 2008-07-21 2010-01-29 삼성전자주식회사 냉장고 및 그 제어방법

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3764032A4 (fr) * 2018-03-08 2021-12-01 LG Electronics Inc. Réfrigérateur
US11530866B2 (en) 2018-03-08 2022-12-20 Lg Electronics Inc. Refrigerator
EP4194784A4 (fr) * 2020-08-06 2024-07-24 Lg Electronics Inc Réfrigérateur

Also Published As

Publication number Publication date
ITTO20120923A1 (it) 2014-04-20

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