COMMERCIAL REFRIGERATOR WITH ENERGY SAVING MODE

Abstract

A commercial refrigerator for energy savings and a method to operate thereof. The refrigerator comprises a cabinet, the cabinet with a first cavity with an inner part, an access to said inner part and an air chamber set in the inner part, the air chamber comprising a fan which makes the air pass through an evaporator, a thawing resistance which thaws the evaporator, a cover with first slits which allow an air flow emanating from the first cavity towards the inner part of said air chamber and second slits that allow air flow cooled by the evaporator emanating from the inner part of said air chamber to the first cavity; temperature sensors set within the inner part of the air chamber, a first temperature sensor set between the first slit and the fan and a second temperature sensor set between the evaporator and the second slits, said sensors connected to an electronic control. The method collects temperature data from a sensor and temperature data from another sensor within an air chamber; compares the data from one sensor to the data from the other sensor to obtain a temperature value and calculates the stability of the data from the comparison; averages said data such that the temperature obtained is presumed as very close to the temperature of the products within the inner part of a chamber; de-energize a compressor by means of an electronic control.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. §119(a) to Mexican Patent Application Serial No. MX/a/2015/013583, filed Sep. 14, 2015, the contents and disclosure of which is hereby incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

Present invention lies in the field of refrigerators, particularly commercial refrigerators which may be found in convenience, self-service or supermarket stores, which store cans, containers or receptacles with some liquid; the commercial refrigerators consist of a translucent door which allows glancing into their inner part, and as opposed to household refrigerators, the commercial refrigerators do not have a freezer as a separate compartment from the fresh food one. It is very desirable for these commercial refrigerators to be able to provide their depositary or owner, a type of energy savings, knowing that the electrical energy that these appliances consume directly impacts the indirect operational costs of the convenience, self-service or supermarket store, thus low energy consumption is highly desirable, to such an extent that some convenience store owners unplug or disconnect these appliances when closing the store, the problem they then face is that sometimes the products are “warm” upon opening the store, which is bothersome to customers, or which in some cases could damage conservation of the liquids needing to be conserved, and thus the need arises of providing a commercial refrigerator with the necessary means that it may turn on an energy savings mode when the store is closed or there is no clientele present and reactivate itself prior to store opening or its contents are sought by a customer desiring a beverage at an appropriate temperature.

BACKGROUND OF THE INVENTION

Various efforts have been taken in the field of commercial refrigerators to overcome the above described problem, a document worth studying is US 4417 450 by Morgan et al, in which a commercial refrigerator is described with electronic control means based on a microcontroller paired with a hand device which allows communicating with the microcontroller to thus modify operation parameters, without having the possibility of modifying the logic or programming of the microcontroller, and thanks to a series of sensors the microcontroller may determine if it is in a high sale stage, in which case it can determine to change its temperature parameters to ensure correct inner cooling of the beverages to be sold, it also consists with a clock which allows programming its periodic cooling functions as well as the periods of continuous compressor operation which are used for recovering the temperature right after a low or no sales period. The above patent has the inconvenience of basing the energy savings functions on an agenda type, where the user can program what days and hours have low or no sales; which can vary, if this happens it needs to be reprogrammed through the hand held device, which is inconvenient, being obvious that the technician needs to be called in or to have the handheld device available, as well as needing to know how to use it, additionally the system cannot adapt itself to the sale conditions, being highly inconvenient by requiring constant parameter modifications by the user.

Another document of particular interest is U.S. Pat. No. 7,200,467 by Schanin et al describes a method and apparatus for handling energy consumption which monitors the refrigerator door at all times, noting if its open or closed as well as its opening frequency, also having means of monitoring air temperature in the refrigerator's interior, which are compared at all times with the programmed values (set point); it references that it consists with at least two operation modes, a normal as well as an energy savings mode, so that depending on if the door is open, it can determine changing the operation mode, in another embodiment it can also consider the inner air temperature of the refrigerator to determine being in a determined operation mode; this document is based on monitoring the air temperature yet not giving much importance to the objects stored inside, which is inconvenient to the customer knowing that if the temperature near the sensor is within the parameters, but the lower part of the refrigerator is filled with room temperature drinks, the sensor will not be alerted to the situation, as it does not try to calculate the temperature of the objects or cans stored in its inner part in any way, which can cause the refrigerator to change into energy savings mode, when what was truly required was for it to enter into normal working or recovery mode to cool said cans in case of high demand of these.

Document US 2005/0177282 by Mason describes a commercial refrigerator with an energy savings function which stores rest periods in a memory to thus attempt to predict active and rest times, with which it creates a series of active and rest patterns, the problem with these types of solutions is that they consume too much microcontroller memory, and they cannot be adapted or predict a holiday, as the memory and pattern typically encompass only a week; to encompass a greater time period, a larger memory would be required, the description fails to indicate how the commercial refrigerator makes known to the microcontroller that it is undergoing high demand, as it does not count the times the door is opened, nor the time it remains open, nor does it consider the temperature within the refrigerator, it merely takes for granted that in some way the electric control knows said information to then form patterns of the use.

Another document is U.S. Pat. No. 6,745,581 by King et al which describes a commercial refrigerator consisting of a temperature control device connected to an electronic control, the document does not describe what the temperature control device refers to, but it can be assumed that it is an electronic or electromechanical system consisting of a temperature sensor in charge of turning the compressor on or off depending on the target temperature programmed by the user, it appears that the functioning of said temperature control device is subject to the orders of an electronic control, which send a signal from said device to the different actuators such as the compressor, fan or lighting system, the electric control also enables or modifies the target temperature of the referred to device depending on the mode in which it is functioning, the electronic control requires a movement or presence sensor, which combined with a sensor on the door of the commercial refrigerator, detects and stores use patterns to predict when to enter into an energy savings or store closing mode, storing in the memory the time in which movement around the refrigerator is detected and the times that the door is opened and with these design use patterns, which are stored in the memory, the system requires storing data at least 3 weeks; thus a large microcontroller memory is required, it is also noted that the system is also highly expensive to implement given that a “normal” temperature control is adhered in some way to an electronic control for governing the first, highly increasing the cost in addition to the microcontroller requiring storage of a large amount of data for processing and determining when in must enter into the energy savings mode or operate in a normal manner, this also increases the control system cost by having to use high capacity storage microcontrollers or at least provide the electronic control with the necessary means to store the data.

BRIEF DESCRIPTION OF THE INVENTION

Commercial refrigerators have traditionally had an energy savings mode, some models can be seen with a timer coupled to an electro-mechanic control system, where the timer allows energizing the system or the compressor itself within a determined time interval, programmed by the user, which worked well for a time period, the problem with the above described system is that it does not know when a low or high demand of the product exists, when it was loaded with new product or if there is a holiday or low activity Sunday, or conversely, if it is a high demand weekday or weekend, all depending on the establishment's business style and model where the commercial refrigerator is found; to avoid multiple adjustments by the user, which is undesirable, leads us to think that a commercial refrigerator which can auto-determine its operation mode is desirable, as it is a cost saving tool given its energy consumption as well as human resource efficiency. Present invention aims to provide a commercial refrigerator able to automatically determine its operation mode, depending on the demand of the objects stored within it for a determined time lapse and thus provide the user significant electrical energy savings; another objective of present invention is to provide said commercial refrigerator a new temperature measuring algorithm which determines with a good degree of exactness the temperature of the stored objects, so that its target temperature value (set point) programmed by the user, refers to the objects contained inside it, not just to the air temperature detected by the sensors, making the commercial refrigerator's operation more precise, now then, the control of present commercial refrigerator, does not store large amounts of information to be able to determine the change of operation mode, this is carried out efficiently counting the time the compressor is turned on in normal operation mode, as well as in energy savings and recovery mode; based on this predict when it is likely that demand for the products inside the refrigerator will begin, another peculiarity of present invention is using two temperature sensors, one placed in the air return precisely at the evaporator intake, the other placed at the exit of the air evaporator, thus with these two sensors, readings are taken which upon processing them allows knowing the temperature of the objects to be sold within the refrigerator of present invention with exactness, so that the target temperature (set point), set by the user, will refer at all times to the temperature of the objects found within the refrigerator, not to the temperature of the air measured at some point in the refrigerator.

DESCRIPTION OF THE FIGURES

FIG. 1 shows a vertical cut of the refrigerator object of present invention.

FIG. 2 shows an upper view of the air chamber of the refrigerator object of present invention.

FIG. 3 shows a block diagram of the peripherals of the electronic control.

FIG. 4 shows a flow diagram of the method object of present invention.

FIG. 5 shows a flow diagram of an alternative embodiment of the method object of present invention.

FIG. 6 shows a temperature diagram representing the different operation modes of the method object of present invention.

FIG. 7 shows a temperature diagram representing the temperature profile obtained by the temperature sensors through time.

DETAILED DESCRIPTION OF THE INVENTION

Present invention lies in the field of refrigerators, particularly commercial refrigerators, this does not limit that the use of present invention, as it may be used in a household refrigerator, industrial refrigeration chambers or related equipment.

FIG. 1 shows a cross cut of a commercial refrigerator 29, where the cabinet 11 can be seen, which on its outer part is formed by a body preferably made of steel and on its inner part by a liner or cover (not shown) preferably made of some thermo-formable thermoplastic, in the space of these two some type of commercial foam is used which functions as a thermal insulator; as can be seen in FIG. 1, the cabinet 11 is disposed with two cavities, the upper cavity being the sales cavity 20, where the objects to be cooled (not shown) are placed (preferably refreshment or soda cans), in the lower cavity 21 of the cabinet 11, the compressor 15 as well as the condenser 16 are found, in an alternative embodiment of the invention, the condenser 16 or the lower cavity 21 can be set with a fan 17 (not shown) which aids the forced convection of said elements 15 and 16, which can improve its performance, the referred to fan 17 in an alternative embodiment of the present invention will become energized as long as the compressor 15 remains energized, to avoid tedious repetitions it will be understood that each time the compressor 15 becomes energized, the fan 17 will become energized as well; now turning our attention to the upper cavity 20 it is also disposed with a series of shelves 18 which are preferably manufactured of steel bars welded and painted in grill manner, this aids in supporting the objects set on them, in addition to allowing the flow of air through them, which helps in improved convection within the upper cavity; the upper cavity 20 is found covered by a door 10, which is hinged on a vertical side of the referred to cabinet 11 which allows having or denying access to the inner part of the upper cavity 20, the referred to door 10 is set with an interrupter or door opening sensor 28 set on some place of the front frame of the upper cavity 20; the referred to upper cavity 20 is disposed with a lighting system which consists with a lighting source 19 such as a bulb or led preferably set over the cover (not shown) of the air chamber, in an alternative embodiment, the referred to lighting source 19 can be set over the cover or liner 12 within the upper cavity 20, in another alternative embodiment, the lighting source may be mounted over the door frame 10 with such luck that it lights towards the inner part as well as the door itself, yet in another alternative embodiment, the refrigerator of present invention can additionally be set with an advertisement sign, which is lit by means of a lighting source 19 set behind the referred to advertisement sign, further, in yet another embodiment, all of the above options lighting options may be combined or have them all simultaneously.

Turning our attention to the upper part of the upper cavity 20, we find the air chamber 22 which is made up of a cover 23, in the inner part of the air chamber 22 we find a fan 24 which may be made of blades or squirrel cage, its function is to suction the air within the upper cavity to force it to pass through the evaporator 25 to be able to carry out the heat transfer and thus provide cold air to the upper cavity, the cold air is injected by the upper back part of the upper cavity 20 such as shown in FIG. 1; it should be mentioned that the cover 23 has a series of slits which allow the passage of air towards the fan and another series of slits which allow for the fluid passage of cooled air emanating from the evaporator 25 towards the upper cavity 20; it should be noted at this point that the evaporator 25 consists on its lower part with a thawing resistance 32, which may be energized by means of the electronic control 30 to carry out the thawing of the evaporator 25.

FIG. 2 shows an upper view of the air chamber 22, where the fan 24, the evaporator 25 and the temperature sensors 26 and 27 can be seen, the sensor 26 is set at the air intake emanating from the upper cavity just prior to or in the vicinity of the fan 24, the temperature sensor 27 is set at the exit of the air emanating from the evaporator 25, with such luck that the temperature sensor 26 detects the air temperature at the intake of the air chamber 22, and on the other hand, the temperature sensor 27 detects the air temperature at the exit of the air chamber 22, both sensors 22 are connected to an electronic control 30, which receives information from the two temperature sensors 26, 27 to process said data, such as will be described in detail further below.

Focusing our attention on the electronic control 30, this consists with a power stage, which allows it to connect to the alternating current, to later pass it through a rectifying stage which will be able to provide continuous current, preferably 5V CC, which allows feeding the microcontroller, which preferably is an 8 bits and flash memory microcontroller, which receives data from the different sensors and emits signals or pulses to the drivers of the different actuators to energize or de-energize these according to the method object of present invention, the drivers are found at the exit power stage, said drivers can be transistors, traits, relays, among others; the function of these is to receive a low voltage signal or pulse which allows activating a type of high voltage interrupter which allows the flow of high voltage energy to the actuators, such as the fans 17 or 24, compressor 15, lighting source or sources 19, thawing resistance 32 etc., so that in order to repeat tedious repetitions, mention will only be made of the electronic control which will energize or activate certain actuator to be understood that this sends a pulse to the driver in particular of said actuator so that this becomes energized; it also occurs this way with the sensors as these may require some type of signal conditioner such as an operational amplifier or another type of signal conditioner, which allows granting the microcontroller a signal within its specified operational parameters, thus in order to avoid a multitude of tedious repetitions, it will merely be indicated that the signals, pulses, data or by means of the multiple sensors 26, 27, 28, the electronic control will acquire the necessary information to process it. In FIG. 3, a functional block diagram can be seen of the interconnection of the electronic control 30 with the different actuators and sensors which make up the refrigerator object of present invention; whose operation method will be addressed below.

Determination of the Temperature of the Objects Within the Refrigerator—

As referred to above, the electronic control 30 can determine the temperature of the objects to be cooled housed in the upper cavity 20 with great exactness, this is achieved by means of the temperature sensors 26, 27, which detect the air temperature both at the intake as well as the exit of the air chamber 22 respectively; thus when the compressor 15 is resting or de- energized and the fan 24 is energized, the electronic control 30 begins to request data from the referred to sensors 26, 27, once the data has been requested by the electronic control 30, this begins to compare the data from the sensors 26, 27 to each other, in such a way that it calculates the difference of the temperature between these, once the referred to temperature difference reported by the sensors 26, 27 is stable (i.e. that it has a 1° C. maximum variation); in the preferred embodiment of the present invention, the electronic control 30 carries out an average of certain number of data per each sensor 26, 27, once having the averages of each sensor, the referred to electronic control 30 averages them between them; which grants a value highly approximate to the temperature of the objects 14 housed within the inner part of the upper cavity 20 (see FIG. 7), in the preferred embodiment of present invention, the electronic control 30 upon recompiling the data of each sensor 26, 27, while the compressor 15 is de-energized and the fan 24 energized, once the temperature readings emanating from the sensors 26, 27 have been stabilized (such as above described), the electronic control 30 proceeds to average them to obtain an average temperature value of the readings of the sensors 26, 27, such as can be seen in FIG. 7, wherein the temperature graphs of the sensors 26, 27, as well as their average, it can be inferred that while the compressor 15 is at rest and the fan 24 is found energized, the temperature obtained from the averaging of temperature values by the referred to sensors 26, 27 is very similar to the temperature of the objects placed within the refrigerator 29 (having an experimental variation less than 1° C. between the average temperature obtained by the sensor 26, 27 values and the average temperature of the objects housed within the refrigerator 29); it should also be highlighted at this point that such as can be seen in FIG. 7, the differential of the temperature readings of the sensors 26, 27 is also minimal, where its variation is lesser than 1° C. for most of the time that the compressor 15 is turned off and the fan 24 is energized; so that in an alternative embodiment the electronic control 30 can take as a reference temperature the value obtained by the sensor 26, 27 jointly or separately. Now then, we can be sure of this thanks to a series of laboratory tests and studies which helped fine tune this method; it should be noted that the location of the sensors 26, 27 within the air chamber 22 as well as carrying out the temperature measurements of the sensors 26, 27, ensuring that the door 10 is closed, the fan 24 energized, as well as the compressor 25 de-energized or resting state, are vital to achieving an approximation to the temperature of the objects housed within the upper cavity 20 is successful.

Such as can be seen in FIG. 7, when the compressor 15 is energized, the temperature values of the sensors 26, 27 are separated, that is, the difference between them grows or increases, and said differential depends on the outer temperature as well as on the construction of the refrigerator 29 itself, thus determining it, can be somewhat complicated; thus in the preferred embodiment of present invention, the electronic control 30 when the compressor 15 as well as the fan 24 are energized, the door 10 is closed, the electronic control 30 takes as a reference temperature, the temperature values obtained by the sensor 27, which is found at the exit of the evaporator, thus the electronic control 30 compares the value of the target temperature vs. the temperature value obtained by means of the sensor 27, once the temperature value obtained by means of the sensor 27 is equal or lesser than the target temperature value (which preferably oscillates at 0° C.), the electronic control will determine to de-energize the compressor 15.

Normal Mode of Operation

In the normal mode of operation, the electronic control 30 begins by determining the temperature of the objects housed within the inner part of the upper cavity 20, such as above described, once the temperature value of the objects housed within the inner part of the upper cavity 20 has been determined it orders a timer to start for a 24 hour period known as cycle time, which in a nested manner carries out the time count during which the compressor 15 is turned on during the normal operation mode—wherein said value will be termed Ton1—it also starts a second timer which will count the time that the energy savings mode is active, the referred to value is termed TMN; now then, in a preferred embodiment, the target temperature value of the objects stored within the inner part of the refrigerator 29 is already set in the memory of the electronic control 30, that is, there is no user interface 31, in an alternative embodiment the user by means of the user interface 31 in which the alternative embodiment preferably can consist with at least one pair of screens or LED displays with 7 segments as well as with a potentiometer, encoder, knob or button which allows modifying the value of the target temperature or “set point”; thus the user interface 31 will send the recompiled information by the adjustment means (potentiometer, encoder, knob or button among others), with which the target temperature value will be set within the inner part of the cavity 20; given that it consists with the target temperature value in the electronic control 30, the temperature control is carried out in the following manner; with the compressor 15 in resting state, the fan 24 is energized and the door 10 closed, the temperature of the objects housed within the inner part of the upper cavity 20 is determined, such as described above, the electronic control 30 compares the temperature it determined for the objects housed within the inner part of the upper cavity 20 (which should oscillate around 3° C.) versus the target temperature, this is done repeatedly until the electronic control 30 finds that the determined temperature of the objects housed in the inner part is higher than the target temperature; in an alternative embodiment the electronic control 30 can use the value obtained by one of the sensors 26, 27 either jointly or separately to compare it to the target temperature (which should oscillate around 3° C.) of the objects housed within the inner part of the upper cavity 20 of the refrigerator 29; once this occurs, the compressor 15 is energized which causes the evaporator 25 to lose heat, in turn cooling the air going through it; such as described above the compressor 15 is kept energized until the value obtained by means of the temperature sensor 27 is equal to or lesser than the target temperature value, that is: the electronic control 30 when the compressor 15 is energized will acquire the data from the sensors 26, 27, from which it will take the temperature reference value of the objects housed within the upper cavity 20 the temperature value obtained by the sensor 27 which is near the evaporator 25; said temperature value of the electronic control 30 will compare it to the target temperature value (which oscillates around 3° C.) of the objects set within the upper cavity 20, once the value obtained by the temperature sensor 27 is equal to or lesser than the target temperature, the electronic control 30 will determine to de-energize the compressor 15, in a preferred alternative embodiment, the electronic control 30 undertakes an average of the temperature reading it obtains through the temperature sensors 26, 27, from this average a correction or error factor is added algebraically (which can be determined experimentally and which depends on the particular construction of the refrigerator 29), with this the electronic control 30 compares the target temperature value to the average value obtained by the sensors 26, 27, already taking the error or correction factor into account, once this last value is equal to or less than the target value, the electronic control 30 will determine to de-energize the compressor 15; in another alternative embodiment, the electronic control 30 can maintain the compressor 15 energized for a determined time interval (which will depend on the particular construction of the refrigerator 29 and can be determined experimentally) e.g. 30 minutes; in both cases, the electronic control 30 will count the time that the compressor 15 remains energized and store this in the memory.

All this takes place while the door 10 remains closed, once opened, the electronic control 30 by means of the door sensor 28 determines that the door has been opened, this de-energizes the fan 24; also energizes the lighting source(s) 19 set on the commercial refrigerator 29; when the electronic control 30 detects the door has been closed thanks to the door sensor 28, this resumes the activity which it was undertaking prior to the door opening, so that the electronic control 30 returns to determine the temperature of the objects set in the inner part of the upper cavity 20, or to its cooling mode energizing the compressor 15, in any of its above described embodiments.

Energy Savings Mode

Once the electronic control 30 has determined that for a period of time, (i.e. 30 minutes) the door 10 has not been opened, it then orders entering into an energy savings mode; here the electronic control 30 begins a timer termed TMA which counts the time that the refrigerator 29 is in the energy savings mode, it also de-energizes the fan 24 for determined periods of time, e.g. 5 minutes, energizing them again for a determined period of time, e.g. 60 seconds, in which the electronic control 30 will calculate the temperature of the objects housed within the inner part of the upper cavity 20, such as described above (in an alternative embodiment the electronic control 30 may also de-energize the lighting source(s) 19); in addition to recovering the time value which the compressor has been energized, within the determined time period (e.g. 24 hours) which the timer has been counting, these data are recovered to be able to determine the time lapse which the refrigerator 29 can remain in energy savings mode, so that once the time has transpired, then enter into recovery mode.

In the preferred embodiment of the energy savings mode, the electronic control 30 ignores the target temperature value or set point, allowing the objects stored within it to warm or gain heat, until the electronic control 30 determines that it is time to exit the energy savings mode and start the recovery mode; in an alternative embodiment of the present energy savings mode the electronic control may allow a determined temperature differential, e.g. 20° C., thus by being in the energy savings mode energizing the fan 24 for a determined time period e.g. 60 seconds, with which it determines the temperature of the objects housed within the inner part of the upper cavity 20, as described above, thus when the electronic control finds it has reached a temperature higher than the tolerance of the temperature differential it begins its recovery mode.

Returning to the preferred embodiment of the present energy savings mode, the electronic control recovers the time value Ton1, also recovers the time which the normal operation mode was activated TMN, by dividing Ton1/TMN the percentage of time which the compressor 15 was energized is obtained terming said variable as % run1; once % run1 is calculated, the remaining time in energy savings mode termed Trest can be calculated by subtracting 24-TMN; now then, with Trest time being calculated the recovery time, termed Trec is processed, which is the time required to energize the compressor 15 so that the refrigerator 29 reaches the target temperature of normal operation; calculated by multiplying % run1 by Trest; the value of Trest obtained, the electronic control 30 continuously compares the Trest value vs. the time value counting the time that the refrigerator 29 is found in energy savings mode TMA, once TMA≧Trest the electronic control 30 decided exiting the energy savings mode to enter the recovery mode.

If the door 10 is opened during the energy savings mode, this causes the electronic control 30 to return to the normal operation mode. In an alternative embodiment of present invention a tolerance of the door 10 opening can be established, i.e. if for example the door 10 is open less than 3 times for a determined period of time e.g. 15 minutes, the refrigerator 29 will remain in energy saving mode.

Recovery Mode

In the recovery mode the electronic control 30 energizes the compressor 15 and the fan 24 and begins to acquire data from the sensors 26, 27 to compare the determined average temperature vs. the target temperature of the normal operation mode; once the objects within the upper cavity 20 have reached the target temperature, the electronic control 30 de-energizes the compressor 15 to enter the normal operation mode; the electronic control 30 keeps counting the time during which the door 10 has remained closed, until said door 10 is opened, this causes the variables Ton1, % run1, TMN, TMA, Trec, Trest and the cycle time counters to be erased to allow calculating new ones as a new cycle is begun for a determined time period e.g. 24 hours.

Vacation Mode

If after carrying out the recovery mode and the refrigerator 29 being once again in normal operation mode, the electronic control detects that the door has been closed for an extended period of time without being opened, e.g. 15 hours, the electronic control 30 determines entering vacation mode, whereby the electronic control has not erased the Ton1, % run1, TMN, TMA, Trec, Trest values, conserving them to continue operating in the energy savings mode with these values until door 10 is opened.

Thawing Mode

The electronic control 30 itself in a variable alternative termed TonTot adds or accumulates the time which the compressor 15 remains turned on, this is undertaken for thawing purposes, knowing that certain amount of working time of the compressor 15 e.g. every 8 hours of work, the electronic control 30 energizes the thawing resistance 32 for a determined time period which allows thawing the evaporator 25 or until the exit temperature sensor 27 detects a determined temperature, e.g. 30° C.; the thawing mode is preferably carried out when the refrigerator 19 is found in energy savings mode, so that when TonTot is greater than the number of compressor 15 work hours programmed in the electronic control 30, this will take note of it and enter into energy savings mode to undertake thawing process.

Obviously, a person skilled in the art could find variations to the embodiments herein described, these would have to lie within the scope and spirit of the following claims; having described present invention with sufficient detail, it is found as possessing novelty, inventive activity and is found industrially applicable, so that we claim the following claims.

Claims

1. A method for operating a commercial refrigerator with a cabinet, the cabinet with at least one first cavity with an inner part, an access to said inner part and an air chamber set within the inner part, wherein said air chamber set comprises a fan which makes the air pass through an evaporator to carry out a heat transfer, a thawing resistance which thaws the evaporator, a cover with first slits which allow an air flow emanating from the first cavity towards the inner part of said air chamber and second slits which allow an air flow cooled by the evaporator emanating from the inner part of said air chamber towards the first cavity; said method comprising:

setting at least two temperature sensors within the inner part of the air chamber, a first temperature sensor between the first slit and the fan and a second temperature sensor set between the evaporator and second slits, said sensors in connection with an electronic control;

collecting first temperature data from the first sensor and second temperature data from the second sensor within the air chamber;

comparing the first temperature data from the first sensor to the second temperature data from the second sensor to obtain a temperature value and to calculate stability of the first and second temperature data from the comparison;

wherein, if said data is stable, averaging said first and second temperature data such that the temperature obtained is deemed very near the product temperature within an inner part of a first chamber;

and wherein, if the difference between said first and second temperature data increases, de-energizing a compressor by means of the electronic control.

2. The method according to claim 1, wherein once the temperature value of the objects stored within the inner part of the first cavity has been determined, start, by the electronic control, a timer termed as cycle timer, which in a nested manner will keep count of the time in which the compressor remains turned on during a normal operation mode.

3. The method according to claim 2, wherein said cycle time is maintained for a 24 hour period.

4. The method according to claim 2, wherein it also starts a second timer which counts the time that an energy savings mode is active.

5. The method according to claim 1, wherein the target temperature value of the objects stored within the inner part of the refrigerator are already set in the memory of the electronic control.

6. The method according to claim 1, wherein the target temperature value of the objects stored within the inner part of the refrigerator is determined by the user.

7. The method according to claim 4, wherein the energy savings mode comprises de- energizing the fan for determined periods of time and calculating, by means of the electronic control, the temperature of the objects stored in the inner part of the upper cavity, to determine the time lapse at which the refrigerator can be in the energy savings mode.

8. The method according to claim 1, wherein the method additionally comprises energizing both the compressor as well as the fan; acquiring the data from the sensors to compare the determined average temperature versus a target temperature of the normal operation mode;

wherein, once the objects stored within the inner part of the refrigerator have reached the target temperature, de-energizing the compressor to enter into the normal operation mode; and counting the time that an access has remained closed, until said access is opened.

9. The method according to claim 1, wherein the method additionally comprises determining that an access has not been opened for a period of time and conserving the energy savings mode until the door is opened.

10. The method according to claim 9, wherein the time period is 15 hours.

11. The method according to claim 1, wherein the method additionally comprises de-energizing the thawing resistance by means of the electronic control each pre-determined time period and energizing the thawing resistance which allows thawing the evaporator.

12. The method according to claim 11, wherein the pre-determined time period is 8 hours.

13. The method according to claim 1, wherein the electronic control comprises a power stage and a rectifying stage.

14. The method according to claim 13, wherein the rectifying stage grants continuous current to a microcontroller and a flash memory which receives data from the sensors and emits pulses to a plurality of drivers of actuators.

15. The method according to claim 13, wherein the continuous current is 5V.

16. The method according to claim 13, wherein the microcontroller is 8 bits.

17. The method according to claim 13, wherein the drivers are selected from the group consisting of at least one transistor, triac, relay, and combinations thereof.

18. The method according to claim 13, wherein the actuators drive the fans, a compressor, a lighting source and the thawing resistance.

19. The method according to claim 13, wherein the refrigerator comprises a user interface.

20. The method according to claim 13, wherein the user interface is selected from the group consisting of at least one display, potentiometer, encoder, and combinations thereof.