EP2313718B1

EP2313718B1 - A cooling device

Info

Publication number: EP2313718B1
Application number: EP09772566.7A
Authority: EP
Inventors: Mehmet Oturak; Emre Arisoy; Veysi Ercan; Ilkin Tacan; Alper Mirza
Original assignee: Arcelik AS
Current assignee: Arcelik AS
Priority date: 2008-07-04
Filing date: 2009-07-06
Publication date: 2017-09-06
Anticipated expiration: 2029-07-06
Also published as: WO2010000866A3; EP2313718A2; PL2313718T3; WO2010000866A2

Description

The present invention relates to a cooling device comprising a drip tray, wherein the water resulting from the defrost operation is collected.
During usage of cooling devices, the frost deposit formed on the evaporator in time results in a decrease of refrigeration performance. The frost on the evaporator is melted by performing the defrost operation at certain intervals in order to avert this adverse effect. The water from melting is collected in a drip tray. This drip tray needs to be discharged in due course. There are embodiments known in the technique where the drip tray is discharged by the user.
However, when the user empties the drip tray, problems arise such as spilling of water while carrying the drip tray or overflowing of water from the drip tray when not discharged in due time etc. In the technique, in order to avoid these problems, solutions are devised wherein a heater is emplaced in the drip tray and operating this heater at certain intervals for removing the water collected in the drip tray by evaporating. However, since operating the said heater will result in additional consumption of energy, when and how long the heater will be operated becomes more of an issue.
In the state of the art German Patent Application No DE10208558 , the cooling device explained comprises a sensor for determining the water level in the tray. The heater is energized when the water level reaches above a certain level depending on the data received from the sensor.
In another state of the art embodiment, the Japanese Patent No JP9318233 , a cooling device is explained wherein the decision for energizing the heater is based on the output relating to the water level in the evaporating pan and the temperature inside the device.
In the refrigerator explained by the Great Britain Patent No GB780006 , the heater immersed in the water receptacle is energized at low cabinet temperature or pressure, or whenever the compressor motor is stopped.
In another state of the art embodiment, the Japanese Patent Application No JP2004251480 , a heat transfer element is provided between the drip tray and the evaporator. A heat sensor is disposed on the said heat transfer element. The decision for energizing the drip tray heater and the work duration is given by means of the data received from the said heat sensor.
The cooling device explained by the United States of America Patent No US3774406 , wherein the drip tray heater is energized when the suction line temperature and pressure is within limit values determined by the producer, is another embodiment known in the technique.
In the Japanese Patent and Patent Applications No JP2002295958 , JP2003130535 , JP7141557 and JP2000337756 , embodiments are explained wherein the drip tray heater is energized and deenergized depending on the defrost process, for example energizing the heater at a given time before the completion of defrosting and deenergizing at a given time after the completion of defrosting. A cooling device according to the preamble of claim 1 is known from WO 2005/090878 A1 .
However, in these embodiments known in the technique, problems may arise such as operating the heater more than required or less than required and not starting to operate the heater in due time since the time when to start energizing and the operation duration of the heater for evaporating the water in the drip tray cannot be determined effectively. This results in the increase in energy consumption of the cooling device and lowers operational efficiency.
The aim of the present invention is the realization of a cooling device, wherein the energy consumption of the drip tray heater, is decreased.
The cooling device comprises a control unit that determines the operation duration of the heater based on the number of times the door has been opened for evaporating by heating the water collected in the drip tray as a result of melting the ice deposited on the evaporator in the defrost process.
In an embodiment of the present invention, the operation duration of the heater is determined by the control unit by multiplying the number of times the door has been opened by a constant time period saved in the memory by the producer.
In another embodiment of the present invention, the operation duration of the heater is determined by the control unit by multiplying the number of times the door has been opened by a variable time period calculated by using the operational and exterior environmental parameters. Accordingly, the operation duration of the heater is adjusted by taking into consideration the data, for example, whether the exterior environment temperature is low or high, or the duration of the previous defrost process and thereby the heater is operated for the most efficient duration.
In different embodiments of the present invention, the control unit keeps in memory how many times the door has been opened since the heater is last operated or since a certain time period to assess the number of times the door is opened and determines the operation duration of the heater according to this data.
In the preferred embodiment of the present invention, the control unit resets to zero the number of times the door has been opened saved in the memory when the heater is operated.
In an embodiment of the present invention, the cooling device comprises at least one compressor for performing the refrigeration cycle and a single cabin. In this embodiment, the control unit energizes the heater whenever the compressor is not operating.
In another embodiment of the present invention, the cooling device comprises more than one cabin, more than one evaporator disposed in each of these cabins and a valve that controls transfer of the refrigerant to the evaporators. In this embodiment, the control unit energizes the heater in the drip tray of each evaporator when the valve is in the position of preventing refrigerant delivery to the respective cabin.
In an embodiment of the present invention, the control unit energizes the heater when the evaporator temperature is within a certain interval. The upper and lower limit values of the said interval are prerecorded in the memory of the control unit by the producer or are calculated by the control unit using the operational and/or exterior environmental parameters.
In another embodiment of the present invention, the control unit does not energize the heater if the door is not opened at all since a certain time period.
In an embodiment of the present invention, the control unit energizes the heater when all of the following conditions are met: the door is opened at least once since a certain time period, the refrigerant not being delivered to the cabin containing the heater and the evaporator temperature is within the desired interval.
By means of the present invention, the heater is operated at the right time and as long as required. Consequently, the energy wastage and loss of efficiency due to operating the heater more than necessary is prevented.
The model embodiments relating to a cooling device realized in order to attain the aim of the present invention is illustrated in the attached figures, where:

Figure 1 - is the schematic view of a cooling device.
Figure 2 - is the schematic view of another embodiment of the present invention.
Figure 3 - is the flow chart of the cooling device control method embodiment.

The elements illustrated in the figures are numbered as follows:

1. Cooling device
2. Cabin
3. Door
4. Evaporator
5. Drip tray
6. Heater
7. Control unit
8. Compressor
9. Valve

The following symbols are used in explicating the cooling device (1) of the present invention:

t_heater: The operation duration of the heater (6)
t_heater-max: The longest operation duration of the heater (6)
n_door: The number of times the door (3) has been opened
T_eva: Temperature of the evaporator (4)
T_evamin: The minimum temperature of the evaporator (4) for operating the heater (6)
T_evamax: The maximum temperature of the evaporator (4) for operating the heater (6)

The cooling device (1) comprises at least one cabin (2) wherein articles to be cooled are placed, one or more doors (3) allowing access into the cabin (2), at least one evaporator (4) that cools the interior volume of the cabin (2) by absorbing the thermal energy, at least one compressor (8) for maintaining the refrigeration cycle, at least one drip tray (5) for collecting the water resulting from melting the frost accumulated on the evaporator (4) and at least one heater (6) for vaporizing the water in the drip tray (5) by heating (Figure 1).
The cooling device (1) furthermore comprises a control unit (7) that determines the operation duration of the heater (6) (theater) depending on the number of times the door (3) has been opened (n_door). Thus, the heater (6) is operated for a sufficient period of time for evaporating the water in the drip tray (5) thereby preventing energy wastage since the operation duration of the heater (6) (theater) is determined with respect to the number of times the door (3) has been opened (n_door) which considerably affects the rate of humidity in the cooling device (1).
In an embodiment of the present invention, the control unit (7) determines the operation duration of the heater (6) (theater) by multiplying the number of times the door (3) has been opened (n_door) with a constant time period (t_c), for example 8 minutes, saved into the memory of the control unit (7) by the producer.
In another embodiment of the present invention, the control unit (7) determines the operation duration of the heater (6) (t_heater) by multiplying the number of times the door (3) has been opened (n_door), with a time period (t_v) calculated by using the operational and exterior environmental parameters.
In an embodiment of the present invention, the number of times the door (3) has been opened (n_door) is the information about how many times the door (3) has been opened since the last time the heater (6) is energized and denergized. In this embodiment, the number of times the door (3) has been opened (n_door) that is saved in the memory of the control unit (7) is reset to zero when the heater (6) is operated.
In another embodiment of the present invention, the number of times the door (3) has been opened (n_door) is information about how many times the door (3) has been opened since a certain time duration determined by the producer, for example in the last 7 hours, and saved in the memory of the control unit (7).
In an embodiment of the present invention, the cooling device (1) comprises a single cabin (2). In this embodiment, the control unit (7) energizes the heater (6) whenever the compressor (8) is not operating (Figure 1).
In another embodiment of the present invention, the cooling device (1) comprises more than one cabin (2), at least one evaporator (4) disposed in each of these cabins (2), at least one drip tray (5) in each cabin (2), at least one heater (6) in each drip tray (5) and a valve (9) that determines the directing of the refrigerant pumped from the compressor (8) to the respective evaporators (4). In this embodiment, the control unit (7) energizes the heaters (6) whenever the valve (9) of the respective cabin (2) does not deliver the refrigerant thereto (Figure 2).
In an embodiment of the present invention, the control unit (7) energizes the heater (6) when the evaporator (4) temperature (T_eva) is between the values of the minimum evaporator (4) temperature (T_evamin) for operating the heater (6) and the maximum evaporator (4) temperature (T_evamax) for operating the heater (6). The said limit values (T_evamin, T_evamax) are prerecorded in the memory of the control unit (7) by the producer or are calculated by the control unit (7) by using the operational and/or exterior environmental parameters.
In another embodiment of the present invention, the control unit (7) does not energize the heater (6) when the door (3) is not opened at all since a certain time period, for example in the last 7 hours. Consequently, operating the heater (6) unnecessarily is prevented thereby conserving energy.
In an embodiment of the present invention, the control unit (7) energizes the heater (6) when:

the door (3) is opened at least once in a certain time period,
if refrigerant is not delivered to the cabin (2) containing the heater (6) and
if the evaporator (4) temperature (T_eva) is between the values of the minimum evaporator (4) temperature (T_evamin) and the maximum evaporator (4) temperature (T_evamax) for operating the heater (6).

In an embodiment of the present invention, the operation of the heater (6) is controlled in the following manner:

Start (100),
Controlling whether the compressor (8) is operating or not (101),
If the compressor (8) is operating, return to the starting step (100),
if the compressor (8) is not operating, compare the evaporator (4) temperature (T_eva) with the minimum evaporator (4) temperature (T_evamin ) and the maximum evaporator (4) temperature (T_evamax) for operating the heater (6) (102),
If the evaporator (4) temperature (T_eva) is lower than the minimum evaporator (4) temperature (T_evamin) or higher than the maximum evaporator (4) temperature (T_evamax) for operating the heater (6), return to the starting step (100),
If the evaporator (4) temperature (T_eva) is between the minimum evaporator (4) temperature (T_evamin) and the maximum evaporator (4) temperature (T_evamax) for operating the heater (6), control whether or not the number of times the door (3) has been opened (n_door) is different from zero (103),
If the number of times the door (3) has been opened (n_door) is zero, return to the starting step (100),
if the number of times the door (3) has been opened (n_door) is different from zero, operate the heater (6) (104),
Compare operation duration of the heater (6) (theater) with the longest operation duration of the heater (6) (t_heater-max) and the result of multiplying the number of times the door (3) as been opened (n_door) with a constant time (t_c) saved in the memory of the control unit (7) by the producer (105),
If the operation duration of the heater (6) (theater) is equal to the longest operation duration of the heater (6) (t_heater-max) or to the result of multiplying the number of times the door (3) has been opened (n_door) with a constant time (t_c) saved in the memory of the control unit (7) by the producer, then the heater (6) is deenergized whereby the operation duration of the heater (6) (theater) and the number of times the door (3) has been opened (n_door) are reset to zero (106),
Return to the starting step (100) (Figure 3).

Consequently, the heater (6) is energized at the required time and for as long as necessary by using information of the number of times the door (3) has been opened (n_door), thereby reducing energy consumption and maintaining the efficient operation of the cooling device (1).

Claims

A cooling device (1) comprising:
at least one cabin (2) wherein articles to be cooled are placed, one or more doors (3) allowing access into the cabin (2), at least one evaporator (4) that cools the interior volume of the cabin (2) by absorbing thermal energy, at least one compressor (8) for maintaining a refrigeration cycle, at least one drip tray (5) for collecting water resulting from melting of frost accumulated on the evaporator (4) and at least one heater (6) for vaporizing the water in the drip tray (5) by heating, said cooling device being characterized by a control unit (7) configured to determine the operation duration of the heater (6) (theater) depending on the number of times the door (3) has been opened (n_door).
A cooling device (1) as in Claim 1, characterized in that the control unit (7) determines the operation duration of the heater (6) (theater) by multiplying the number of times the door (3) has been opened (n_door) with a constant time period (t_c) saved in the memory of the control unit (7) by the producer.
A cooling device (1) as in Claim 1, characterized in that the control unit (7) determines the operation duration of the heater (6) (theater) by multiplying the number of times the door (3) has been opened (n_door) with a time period (t_v) calculated by using the operational and/or exterior environmental parameters.
A cooling device (1) as in any one of the above Claims, characterized by a control unit (7) that uses information about how many times the door (3) is opened since the last time the heater (6) was energized and deenergized as the number of times the door (3) has been opened (n_door) and resets the number of times the door (3) has been opened (n_door) saved in the memory to zero when the heater (6) is operated.
A cooling device (1) as in any one of the Claims 1 to 3, characterized by a control unit (7) that uses the information about how many times the door (3) is opened since a certain time period determined by the producer and saved in the memory as the number of times the door (3) has been opened (n_door).
A cooling device (1) as in any one of the above Claims, characterized by more than one cabin (2), at least one evaporator (4) disposed in each of these cabins (2), at least one drip tray (5) in each cabin (2), at least one heater (6) in each drip tray (5) and at least one valve (9) that determines the directing of the refrigerant pumped from the compressor (8) to the respective evaporators (4) and a control unit (7) that energizes the heaters (6) whenever the valve (9) of the respective cabin (2) does not deliver refrigerant thereto.
A cooling device (1) as in any one of the above Claims, characterized by a control unit (7) that energizes the heater (6) when the evaporator (4) temperature (T_eva) is between the limit values of the lowest evaporator (4) temperature (T_evamin) and the highest evaporator (4) temperature (T_evamax).
A cooling device (1) as in the above Claim 7, characterized by a control unit (7) wherein the limit values (T_evamin. T_evamax) of the evaporator (4) temperature (T_eva ) are prerecorded in the memory by the producer.
A cooling device (1) as in the above Claim 7, characterized by a control unit (7) that calculates the limit values (T_evamin, T_evamax) of the evaporator (4) temperature (T_eva) by using operational and/or exterior environmental parameters.
A control method for a cooling device (1) as in Claim 1, comprising the steps of:
- Starting the process for deciding to operate the heater (6) (100),

- Controlling whether the compressor (8) is operating or not (101),

- If the compressor (8) is operating, return to the starting step (100),

- if the compressor (8) is not operating, compare the evaporator (4) temperature (T_eva) with the minimum evaporator (4) temperature (T_evamin) and the maximum evaporator (4) temperature (T_evamax) for operating the heater (6) (102),

- If the evaporator (4) temperature (T_eva) is lower than the minimum evaporator (4) temperature (T_evamin) or higher than the maximum evaporator (4) temperature (T_evamax) for operating the heater (6), return to the starting step (100),

- If the evaporator (4) temperature (T_eva) is between the minimum evaporator (4) temperature (T_evamin) and the maximum evaporator (4) temperature (T_evamax) for operating the heater (6), control whether or not the number of times the door (3) has been opened (n_door) is different from zero (103),

- If the number of times the door (3) has been opened (n_door) is zero, return to the starting step (100),

- if the number of times the door (3) has been opened (n_door) is different from zero, operate the heater (6) (104),

- Compare the operation duration of the heater (6) (theater) with the longest operation duration of the heater (6) (t_heater-max) and the result of multiplying the number of times the door (3) has been opened (n_door) with a constant time (t_c) (105)

- If the operation duration of the heater (6) (theater) is equal to the longest operation duration of the heater (6) (t_heater-max) or to the result of multiplication of the number of times the door (3) has been opened (n_door) with a constant time (t_c) saved in the memory of the control unit (7) by the producer, then the heater (6) is deenergized whereby the operation duration of the heater (6) (t heater) and the number of times the door (3) has been opened (n_door) are reset to zero (106),

- Returning to the starting step (100).