TECHNICAL FIELD

The present disclosure relates to a refrigerator and more particularly to a refrigerator having a cooled compartment that can be operated in different modes.

BACKGROUND

Refrigerators are used to keep goods such as food and the like at a cooled temperature in a cooled compartment. If the refrigerator is used to keep the goods at a temperature below the freezing point the refrigerator is sometimes called a freezer. However, the term refrigerator will be used for any apparatus used to store goods at a cooled temperature such that the temperature inside the refrigerator can be lower than the ambient air outside the refrigerator.

In a refrigerator, the temperature is typically kept at a narrow band around a set temperature. Refrigerators can be designed in various ways to provide functionality requested by the user. For example, US2004144128 describes a refrigerator where a compartment of the refrigerator is a convertible compartment selectively operable by the user as an above freezing refrigerator compartment or as a below freezing freezer compartment.

There is a constant desire to improve the operation of a refrigerator. Hence, there exists a need for an improved control of a refrigerator.

SUMMARY

It is an object of the present invention to provide an improved control of a refrigerator.

This object and/or others are obtained by the refrigerator as set out in the appended claims.

As has been realized by the inventors, when a cooled compartment of a refrigerator can be run in different modes it can be advantageous to automatically apply different defrost sequences depending on the current mode of operation. For example, when defrosting a freezer compartment converted to a chiller, such an automatic change of defrost sequence can avoid disrupting the temperature regulation while defrosting.

For example, there can be a risk of over-heating the cooled compartment if the same defrost sequence is used when the refrigerator is run as a chiller.

Thus, in accordance with the invention, a refrigerator comprising a cooled compartment and a cooling arrangement comprising a compressor for cooling the cooled compartment is provided. A controller is configured to control the cooling arrangement. The controller is configured to control the temperature of the cooled compartment in two different modes of operation, depending on a temperature setpoint for the cooled compartment such that a first mode of operation is activated if the temperature setpoint of the compartment is below a predetermined temperature threshold value, and that a second mode of operation is activated if the temperature setpoint for the cooled compartment is above the predetermined temperature threshold value. Further, the controller is configured to execute a first defrost sequence when the cooled compartment temperature is controlled in the first mode of operation. The controller is configured to execute a second defrost sequence when the cooled compartment temperature is controlled in the second mode of operation, where the second defrost sequence is different from said first defrost sequence. Hereby, the refrigerator can automatically apply a defrost sequence that is tailored to the current mode of operation whereby defrosting always can be performed in a suitable way.

In accordance with one embodiment, a fan can be provided inside the cooled compartment and controlled by the controller. The controller can be configured to stop the fan during at least a part of said first defrost sequence when executing said first defrost sequence. Hereby an efficient defrosting can be performed.

In accordance with one embodiment, the controller is configured to run the fan during the entire second defrost sequence when executing said second defrost sequence or at least for a larger fraction of the second defrost sequence than when executing said first defrost sequence. Hereby it can be taken into account the higher temperature of the cooled compartment in the second mode of operation. In accordance with one embodiment, an evaporator is provided inside the cooled compartment, and the controller is configured to execute a softening phase during execution of said first and second defrost sequence, wherein during said softening phase the cooling of the cooled compartment is stopped and wherein when the controller executes the second defrost sequence the termination of the softening phase is based on the temperature of the evaporator inside the cooled compartment. Hereby defrosting can be made more efficient.

In accordance with one embodiment, the controller can be configured to base the termination of the softening phase in the second defrost sequence also on time. Hereby an additional termination condition can be provided to ensure termination.

In accordance with one embodiment, a heater is provided inside the cooled compartment. The heater can typically be located in the proximity to the evaporator. The heater can melt ice on the evaporator in the cooled compartment. The controller is configured to execute a heating phase by activating the heating element during execution of said first and second defrost sequence. Hereby a fast defrosting can be provided.

In accordance with one embodiment, the controller is configured to terminate the heating phase based on the temperature of an evaporator inside the cooled compartment. Hereby an efficient termination condition can be provided.

In accordance with one embodiment, the controller is configured to terminate the heating phase based also on the temperature inside the cooled compartment when executing the second defrost sequence. Hereby an alternative termination condition can be provided.

In accordance with one embodiment, when a fan is provided inside the cooled compartment, the controller is configured to set the fan in an OFF state when executing the heating phase. Hereby air is not circulated in the cooled compartment whereby the air temperature is kept low. In accordance with one embodiment ,when a heater is provided inside the cooled compartment, the controller is configured to run the heater in a continuous or switched mode when executing the heating phase in the first defrost sequence and only run the heater in a switched mode when executing the heating phase in the second defrost sequence. Hereby an efficient defrosting can be obtained in some configurations and or mode settings.

In accordance with one embodiment, the controller is configured to execute a fan delay phase after the heating phase when executing the first defrost sequence during which fan delay phase the fan is controlled to an OFF state. Hereby efficient defrosting can be obtained for some mode settings.

In accordance with one embodiment, the controller is configured to execute a post cooling phase after the fan delay phase when executing during which post cooling phase the controller is configured to boost the cooling of the cooled compartment. Hereby efficient defrosting can be obtained for some mode settings.

The invention can advantageously be used for a freezer that can be converted to a chiller. For example, the predetermined temperature threshold value can be set to a temperature in the range of minus 10 degrees Celsius to zero degrees Celsius (-10 - 0) However, the invention can be applied in other set-ups where a cooled compartment can be run in different modes of operation.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described in more detail by way of non-limiting examples and with reference to the accompanying drawings, in which:

- Fig. 1 is a view of a refrigerator,

- Fig. 2 is a partial cross-sectional view of the refrigerator of Fig. 1 ,

- Fig. 3 is a flow chart illustrating operation of different modes in a refrigerator,

.- Fig 4 is a flow chart illustrating different defrost steps in a first mode of operation, and

- Fig. 5 is a flow chart illustrating different defrost steps in a second mode of operation. DETAILED DESCRIPTION

Aspects of the present invention will now be described more fully. Like numbers refer to like elements throughout. Well-known functions or constructions will not necessarily be described in detail for ease of understanding and/or clarity. It is further to be understood that the features described can be combined in any suitable manner to meet different implementational needs. Further, while the exemplary embodiments described herein are illustrated by a refrigerator having a single cooled compartment, other configurations are envisaged where two or more cooled compartments are provided. The other cooled compartments can have properties different from the exemplified cooled compartment.

In Fig. 1 a refrigerator 10 is depicted. The refrigerator 10 can be any type of appliance designed to keep goods at a cooled temperature and can typically be a household refrigerator or a household freezer. The term refrigerator is used herein to refer to any apparatus used for keeping goods at a temperature cooler than the ambient air. The refrigerator 10 has at least one cooled compartment 14. The cooled compartment 14 can be accessed via a door 16. The door 16 can be any type of opening used for accessing the cooled compartment such as a drawer or so-called French doors. The door can have a user interface 15 associated therewith so that a user can place the refrigerator in different modes of operation or otherwise control settings of the refrigerator. The user interface can of course be located at any suitable location and need not be located in the door 16. The cooled compartment 14 is cooled by a cooling arrangement 18 as is well known in the art. Typically, a compressor 52 is used to drive the cooling arrangement where an evaporator provides cooling to the cooled compartment 14.

The cooled compartment 14 can in a first mode of operation be cooled to a temperature below the freezing point. In such mode of operation, the refrigerator 10 is operated as a freezer. This is termed the freezer mode herein. Typically, in the freezer mode the temperature is well below the freezing point such as below minus 5 or minus 6 degrees Celsius. Usually, the freezer is set to operate at an even lower temperature such as to operate around minus 18 degrees Celsius or even colder. The cooled compartment 14 can further be operated in a second mode of operation where it is cooled to a temperature above the temperature in the first mode of operation. This is termed the chill mode herein. In the chill mode, the refrigerator can be operated at a set temperature higher than in the freezer mode. Typically, in the chill mode the refrigerator can be set to operate at a temperature around the freezing point. For example, the set temperature can be set somewhere in the range of minus 3 degrees Celsius to plus 8 degrees Celsius. Of course, additional mode of operations can also be envisaged such as multiple freezer modes and or multiple chill modes. To set different modes of operation the user can for example sets a temperature setpoint for the cooled compartment. Depending on the temperature setpoint different modes of operation can be activated. Typically, a first mode of operation is activated if the temperature setpoint of the cooled compartment is below a predetermined temperature threshold value, and a second mode of operation is activated if the temperature setpoint for the cooled compartment is above the predetermined temperature threshold value. Typically, the predetermined temperature threshold value can be set to a temperature in the range of minus 10 degrees Celsius to zero degrees Celsius (-10 - 0).

In Fig. 2 a partial cross-sectional view from above along the line A- A of Fig. 1 is shown. In Fig 2 a fan 34 and a heater/heating element 32 are located inside the cooled compartment 14. Also shown is an evaporator 36 of the cooled compartment 14. The heater 32 can advantageously be located in close proximity to the evaporator such that when activated, the heater primarily warms the evaporator. The cooled compartment 14 is here delimited by a rear wall 44 and side walls 12. Inside the walls 12, 44 a controller 52 can be located. The controller 52 is typically located inside the walls but separated from the cooled compartment 14 for example by a liner. The controller 52 can be formed by a single processing unit formed on a Printed Circuit Board (PCB) or similar, or be distributed in multiple different processing units. However, implemented, the controller 52 is configured to control the operation of the refrigerator based on different input signals such as user input signals for user settings, and programmed control algorithms, and also on different sensor signals and similar such as temperature sensor signals. Typically, the controller 52 can control the operation of the fan 34, the heater 32, and the cooling arrangement 18 as well as other functions within the refrigerator 10. It is to be noted that the exemplary configuration of the refrigerator in the example of Figs 1 and 2 only illustrates one of many possible configurations. For example, multiple cooled compartments can be provided.

In Fig. 3 a flow chart illustrating some steps that can be performed in a refrigerator 10 where at least one cooled compartment can operate at least two different modes. Here, a freezer mode and a chill mode as described above are used as examples. First in as step 300 the refrigerator is in an idle mode. In this mode the refrigerator operates in a normal mode in accordance with the settings of a user and preprogrammed control schemes. Next, in as step 301 , a trigger mechanism in the refrigerator demands that the refrigerator enters a defrost mode. Upon receiving the defrost demand in step 301 , it is checked in a step 303 which of a plurality of operational modes that is currently set. The mode set can for example be determined by a user input at some time during operation of the refrigerator. If in step 303 it is determined that the refrigerator is in a first mode of operation, a first defrost mode is executed in a step 305. If in step 303 it is determined that the refrigerator is in a second mode of operation a second defrost mode is executed in a step 307. It is also envisaged that additional modes of operation and additional defrost modes can be used.

In Fig. 4, some exemplary steps that can be executed in a first defrost mode are illustrated. It is to be understood that the exemplary embodiment in Fig. 4 is for illustration only. Not all steps need to be performed and additional steps can be added. In this exemplary embodiment it is assumed that the first mode of operation is a freezer mode and that the second mode of operation is a chill mode. Fig. 4 describes exemplary steps that can be performed in a freezer mode.

First in a step 401 also termed pre-cooling phase, the cooled compartment temperature setpoint is decreased temporarily to prepare the cooled compartment to a successive heating phase. For example, the air temperature setpoint can be decreased by some pre-set temperature parameter value. For example, the temperature can be lowered by one or a few degrees Celsius compared to nominal target temperature in normal operation. In the pre-cooling phase, the cooled compartment cooling can be in an ON state. A fan in the cooled compartment can be in an ON state and a heater in the cooled compartment can be in an OFF state. The precooling phase can be terminated based on a timer. For example, the timer can be set to run the pre-cooling phase for an hour or longer. Alternatively, the pre-cooling phase can be terminated as soon as the compartment temperature reaches a target temperature below the nominal target.

Next, in a step 403 also termed softening phase, the cooling of the cooled compartment is terminated. For example ,the compressor can be switched OFF or the refrigerant is no longer fed to the evaporator cooling the cooled compartment because of the intervention of a valve that closes the circuit or that diverts the refrigerant to other evaporators. The termination of the cooling will gradually increase the temperature of the evaporator. A fan in the cooled compartment can be in an ON state and a heater in the cooled compartment can be in an OFF state. The softening phase can be terminated based on a timer. For example, the timer can be set to run the softening phase for a few minutes such as about 10 minutes. Alternatively, the softening phase can be terminated as soon as an evaporator sensor, when available, rises above a predetermined threshold temperature.

Next, in a step 405 also termed heating phase, the evaporator is made warmer with the aim of melting ice formations over its surfaces. For example, a heater can be activated. In the heating phase, the cooling of the compartment is inhibited and the compressor can be in an OFF state. Also, a fan in the cooled compartment can be in an OFF state and a heater in the cooled compartment can be in an ON state. In the ON state the heater can be operated continuously or in a switched mode. The heating phase can be terminated based on the temperature of the evaporator. For example, the heating phase can be terminated when the temperature of the evaporator is above a predetermined termination temperature. The heating phase can also be terminated based on a timer. For example, the timer can be set to run the heating phase for about 1 hour. The heating phase can be alternatively or as a supplement be terminated by an external device not belonging to the control system. For example, a thermal cut-out or bimetal thermostat can be employed that is able to cut the power to the heater based on its intrinsic temperature threshold. In this case, the algorithm can be configured to detect the heating termination by measuring a drop in the current supplied to the heater or a reduction of the power. Next, in a step 407 also termed dripping phase, the warming of the cooled compartment is stopped, the cooling of the cooled compartment is not activated yet in this phase. Hereby water is allowed to fall from the evaporator surface after melting. In the dripping phase, the cooling of the cooled compartment can be in an OFF state. A fan in the cooled compartment can be in an OFF state and a heater in the cooled compartment can be in an OFF state. The dripping phase can be terminated based on a timer. For example, the timer can be set to run the dripping phase for about a few minutes such as for example about 10 minutes.

Next, in a step 409 also termed fan-delay phase, cooling of the cooled compartment is resumed. Typically, the cooling arrangement is operated to cool an evaporator to provide cooling to the cooled compartment. In the fan-delay phase a fan in the cooled compartment is in an OFF state to not circulate warm air and wait until sufficient cooling capacity is available. A heater in the cooled compartment is in an OFF state. The fan delay phase can be terminated based on a timer. For example, the timer can be set to run the fan delay phase for about a few minutes such as for example about 5 minutes.

Next, in a step 411 also termed post-cooling phase, the cooled compartment is further cooled. In the post-cooling phase, the cooling can be boosted for example by increasing the compressor speed and /or by diverting all cooling capacity of the cooling arrangement to the cooled compartment being defrosted when there are multiple cooled compartments in the refrigerator. Also, the temperature set point can be lower than during normal operation during the post-cooling phase. For example, the temperature set point in the cooled compartment can be 1 or a few degrees Celsius lower than during normal operation. A fan in the cooled compartment can be in an ON state and a heater in the cooled compartment can be in an OFF state. The post-cooling phase can be terminated based on a set temperature being reached. The post-cooling phase can also be terminated based on a timer. For example, the timer can always terminate the post-cooling phase after some period of time such as after 1 hour. The timer can in some embodiments override the termination based on temperature such that the post-cooling phase never is run for more than a pre-set time set by the timer. When the steps in the defrost mode has finished, the refrigerator can return to a normal mode of operation as illustrated in Fig. 3.

In Fig. 5, some steps that can be executed in a second defrost mode are illustrated. As set out above, it can be advantageous to have different defrost modes for different modes of operation of the cooled compartment. Fig. 5 illustrates some steps that can be performed when the refrigerator is operated in a chill mode. Again, it is to be understood that the exemplary embodiment in Fig. 5 is for illustration only. Not all steps need to be performed and additional steps can be added.

First in a step 501 also termed pre-cooling phase, the cooled compartment temperature setpoint is decreased temporarily to prepare the cooled compartment to a successive heating phase. For example, the air temperature setpoint can be decreased by some pre-set temperature parameter value. For example, the temperature can be lowered by one or a few degrees Celsius compared to nominal target temperature in normal operation. In the pre-cooling phase, the cooled compartment cooling can be in an ON state. A fan in the cooled compartment can be in an ON state and a heater in the cooled compartment can be in an OFF state. The precooling phase can be terminated based on a timer. For example, the timer can be set to run the pre-cooling phase for an hour or longer. Alternatively, the pre-cooling phase can be terminated as soon as the compartment temperature reaches a target temperature below the nominal target.

Next on a step 503 also termed softening phase, the cooling of the cooled compartment is terminated. The termination of the cooling will gradually increase the temperature of the evaporator. For example ,the compressor can be switched of or the refrigerant is no longer fed to the evaporator cooling the cooled compartment. A fan in the cooled compartment can be in an ON state and a heater in the cooled compartment can be in an OFF state. The softening phase can be terminated based on a timer. For example, the timer can be set to run the softening phase for a few minutes such as about 10 minutes. Alternatively, the softening phase can be terminated as soon as the evaporator sensor, when available, rises above a predetermined threshold temperature. Next, in a step 505 also termed heating phase, the cooled compartment is made warmer. For example, a heater can be activated. In the heating phase, the cooling of the cooled compartment is inhibited and the compressor can be in an OFF state. Also, a fan in the cooled compartment can be in an OFF state and a heater in the cooled compartment can be in an ON state. In step 505 the heater can advantageously be operated in a switched mode only with a pre-determined duty cycle. The heating phase can be terminated based on the temperature of the evaporator. For example, the heating phase can be terminated when the temperature of the evaporator is above a predetermined termination temperature. Also, the heating phase can be terminated based on the temperature inside the cooled compartment so that the heating is terminated when the temperature inside the cooled compartment exceeds some threshold temperature. The heating phase can also be terminated based on a timer. For example, the timer can be set to run the heating phase for about 1 hour.

In accordance with one embodiment, the defrost sequence in the second mode performs a sub-set of the steps performed in the defrost sequence of the first defrost mode.