Description:The following specification describes and ascertains the nature of this invention and the manner in which it is to be performed:

Field of the invention
[0001] This disclosure relates to a defrosting device in a household appliance and a method of working of the defrosting device in the household appliance.

Background of the invention
[0002] A refrigerator is a home appliance providing a low-temperature storage that can be opened and closed by a door to store foods at a low temperature. For this, the refrigerator cools the inside of the storage space by using cool air generated by being heat-exchanged with a refrigerant circulated into a refrigeration cycle to store the foods in an optimum state. For this, a power has to be supplied always into the refrigerator. Currently available domestic frost-free refrigerators defrost approximately once per day, which creates a 300–500-watt load during the defrost cycle. Most frost-free refrigerators use an electromechanical timer with switching to run a defrost heater that is placed around the refrigerator evaporator coil. The electromechanical timer is configured to switch to the defrost operation after a certain amount of compressor run time (typically 6 to 12 hours). Thus, the triggering of the defrost cycle is based upon the run time of the compressor. Due to the energy supply problems in, a need exists for a control module that prevents the operation of the defrost cycle of a frost-free refrigerator during peak demand times.

[0003] A US patent 6694753 discloses a device and method for automatically defrosting a refrigeration system only during times of non-peak energy demand. The device is a defrost delay module that plugs into the current defrost timer supplied with frost-free refrigerators. The defrost delay module includes a microprocessor that utilizes a clock to define peak power consumption periods. If the defrost cycle will occur during a peak power period, the delay module interrupts the normal operation and prevents defrosting of a refrigerator or freezer until the peak power periods has passed. The delay module is able to learn the operating characteristics of the defrost timer such that the delay module can be retrofit to existing appliances.

Brief description of the invention:
[0004] It is an object of the invention to provide a defrosting device in a household appliance and a method of operating the defrosting device in the household appliance.

[0005] The objects are solved by a defrosting device in a household appliance and a method of operating the defrosting device in the household appliance having the features according to claims 1 and 9.

[0006] The invention relates to a defrosting device in a household appliance. The household appliance comprises a door to access at least one item stored in the appliance. The appliance comprises a defrosting device adapted to monitor a supply of power to the appliance and adapted to adjust a defrost operating time based on the monitored power supply.

[0007] A feature of this invention is that said defrosting device adapted to monitor the power supply to the appliance for a first predefined time and activates the defrost operation in the appliance for a second predefined time in a normal cooling cycle of the appliance.

[0008] Another feature of this invention is that, the defrosting device adapted to adjust the defrost operating time by varying the second predefined time, if there is a disconnection of the power supply to the appliance during the first predefined time

[0009] Another feature of this invention is that the defrosting device adapted to detect a drop in an electrical parameter in a power detection unit, when the disconnection of the power supply to the appliance is occurred.

[0010] Another feature of this invention is that the power detection unit is made as an integral part of the defrosting device for monitoring the power supply to the appliance.

[0011] Another feature of this invention is that the defrosting device is a chosen from a group of devices comprising a microprocessor, a micro controller, a digital circuit, an integrated chip and the like.

[0012] Another feature of this invention is that, said defrosting device is made operable on any one of means comprising a power supply and a battery.

[0013] Another feature of this invention is that the defrosting device comprises a display unit adapted to display an operating state of the appliance, wherein the operating state is chosen from any one of states comprising a normal working state and a defrost operation state.

[0014] A method of operating the defrosting device in a household appliance is explained in the claim 9 according to the present invention. The method comprises the following steps. In step S1, a supply of power to the household appliance is monitored for a first predefined time. In step S2, a defrost operation in the appliance is activated for a second predefined time, after completing the first predefined time. In step S3, the second predefined time is adjusted upon detecting a disconnection in the power supply to the appliance in the first predefined time.

[0015] Another feature of the invention is that, detecting a drop in an electrical parameter in a power detection unit in the defrosting device when the disconnection of the power supply to the appliance is occurred.

[0017] With the above-disclosed the defrosting device in the household appliance and the method of working of the defrosting device in the household appliance. With the disclosed device, the defrosting in the appliance occurs without any interruption and thus the cooling inside the appliance is maintained. Since, the device adjusts the time of the defrosting based on the supply of the power to the device, the additional load on the compressor will be reduced, as the appliance will not be in an OFF position for a longer period of time. The device disclosed above can be used as a retrofit solution to the existing refrigerators. The device consumes very less power for operating thus making the solution economical and cost effective.

Brief description of the accompanying drawings
An embodiment of the disclosure is described with reference to the following accompanying drawings.
[0018] Figure 1 illustrates a defrosting device in a household appliance, in accordance with an embodiment of this invention, and
[0019] Figure 2 illustrates a flowchart for a method of working of the defrosting device in the household appliance according to the present invention.

Detailed description of the embodiments
[0020] Figure 1 illustrates a defrost device in a household appliance, in accordance with one embodiment of the invention. The household appliance 10 comprises a door 12 to access at least one item stored in the appliance 10. The appliance 10 comprises a defrosting device 14 adapted to monitor a supply of power to the appliance 10 and adapted to adjust a defrost operating time based on the monitored power supply.

[0021] Further the construction of the device in the appliance and the components of the device and the appliance is explained in detail. The appliance 10 as mentioned in this present appliance is a single-door refrigerator. However, the same methodology and the device can be fitted to a multi-door refrigerator or to any of the cooling device (e.g.: Portable cooling device). The door 12 is fitted to the appliance 10 for accessing the stored items inside the appliance 10. The device 14 is a fitted on the door 12 of the appliance 10 or can be any other place on the appliance 10 where it can be operated. The appliance 10 operates in two states, one in a normal running state and other in a defrosting state. In the conventional appliance, the appliance 10 is made to operate in a running/working state for a first predefined time and in the defrosting state for a second predefined time in one normal operating cycle. For example, in a normal operating cycle, the running/working time of the appliance 10 will be ten hours and the defrosting time will be for one hour. These operating cycles will be continued in the appliance 10 for better maintenance of the freezer and to avoid excessive accumulation of the ice in the freezer.

[0022] The defrosting device 14 comprises a display unit 18 adapted to display an operating state of the appliance 10, wherein the operating state is chosen from any one of states comprising a normal working state and a defrost operation state. The defrosting device 14 is a chosen from a group of devices comprising a microprocessor, a micro controller, a digital circuit, an integrated chip and the like. However, the type of the device 14 is not limited to the above-mentioned devices, but can be any other device that is known to a person skilled in the art. The defrosting device 14 is made operable on any one of means comprising a power supply and a battery.

[0023] The defrosting device 14 adapted to monitor the power supply to the appliance 10 for the first predefined time and activates the defrost operation in the appliance 10 for the second predefined time in a normal cooling cycle of the appliance 10. The first predefined time is different will be from second predefined time. According to one embodiment of the invention, the first predefined time is made greater than the second predefined time.

[0024] Another feature of this invention is that the defrosting device 14 adapted to adjust the defrost operating time by varying the second predefined time, if there is a disconnection of the power supply to the appliance 10 during the first predefined time. The device 14 comprises a power detection unit 16, wherein the power detection unit 16 has a resistor circuit 20. When there is a power failure /when supply of the power to the appliance 10 is discontinued, then the voltage across the resistor circuit 20 drops to a minimum value.

[0025] The defrosting device 14 detects the drops in the voltage, when there is a disconnection of the supply in the power to the appliance 10. The device 14 activates the defrosting operation in the appliance 10, upon detecting the drop in the voltage in the power detection unit 16. According to one embodiment of the invention, the power detection unit 16 is made as an integral part of the defrosting device 14 for monitoring the power supply to the appliance 10.

[0026] A method of operating the defrosting device 14 in a household appliance 10 is explained in the claim 9 according to the present invention. The method comprises the following steps. In step S1, a supply of power to the household appliance 10 is monitored for a first predefined time by the defrosting device 14. In step S2, a defrost operation in the appliance 10 is activated for a second predefined time, after completing the first predefined time by the device 14. In step S3, the second predefined time is adjusted upon detecting a disconnection in the power supply to the appliance 10 in the first predefined time. In step S4, a drop in an electrical parameter in a power detection unit is detected in the defrosting device when the disconnection of the power supply to the appliance 10 is occurred. According to one embodiment of the invention, the electrical parameter is a voltage. However, the electrical parameter is not restricted to voltage, but can also be any other electrical parameters comprising current, frequency and the like.
[0027] The above method is explained in detail. In a conventional appliance, during a normal cooling cycle/normal working condition of the appliance 10, the appliance 10 is provided with the power supply from the mains (not shown) continuously. After the first predefined time of the running time of the appliance 10, the defrost operation is activated for the second predefined amount of time for maintaining the level of ice formed in the freezer of the appliance 10.

[0028] But, due to a faulty condition in the supply of the power from the mains, the appliance 10 will not be receiving the power during the first predefined time. For example, if the first predefined time is 10 hours, then due to the power failure in the mains, there won’t be supply of power to the appliance 10 for a certain amount of time, say 2 hours. i.,e instead of appliance 10 running for 10 hours, the appliance 10 will be working for 8 hours . After the first predefined time (i.e., 10 hours), the defrost operation will be activated for the second predefined time, which is 1 hour.

[0029] In this scenario, the compressor (not shown) in the appliance 10 will be in non-working state for three hours, thus reducing the cooling inside the appliance 10. This not only leads to the excessive load on the compressor in the next cooling cycle, but also damages the items stored inside the appliance 10 due to the absence of the power for a longer duration.

[0030] In order to avoid the above stated problem, the defrosting device 14 is installed/fitted in the appliance 10. The device 14 continuously monitors the supply of power to the appliance throughout the first predefined time. I.e., The device 14 monitors the power supply for 10 hours. If there is a failure in the power supply, there will be a drop in the voltage in the power detection unit 16. The defrosting device 14 detects the drop in the voltage in the resistor circuit 20 of the power detection unit 16 and senses the disconnection of the supply of power to the appliance 10. The defrosting device 14 calculates the running time of the appliance 10 in the first predefined time before the failure in the power supply. For example, if the running time of the appliance 10 is 7 hours in ten hours of time period. Then, the defrosting device 14 adjusts the activation of the defrost operation and the defrosting time according to the run time of the appliance 10. Not only it calculates and adjusts the defrosting time, but also detects the amount of ice accumulated in the freezer based on the voltage in the power detection unit 16 during the running time of the appliance 10.

[0031] In this scenario, the defrosting device 14 activates the defrost operation for less than an hour (which is the second predefined time) or activates the defrost operation in the next cooling cycle, if there is not much ice accumulated in the freezer. Thus, the defrosting device 14 helps in reducing unnecessary activation of the defrost operation in the device 14. If there is a power failure for two hours in the 10-hour time period, then the defrost operating time will be adjusted in the next cooling cycle, since the switching off time of the appliance 10 and the activation of the defrost operation will increase the load on the compressor to cool the appliance 10.

[0036] With the above-disclosed the defrosting device 14 in the household appliance 10 and the method of working of the defrosting device 14 in the household appliance 10. With the disclosed device 14, the defrosting in the appliance 10 occurs without any interruption and thus the cooling inside the appliance is maintained. Since, the device 14 adjusts the time of the defrosting based on the supply of the power to the device 14, the additional load on the compressor will be reduced, as the appliance 10 will not be in an OFF position for a longer period of time. The device 14 disclosed above can be used as a retrofit solution to the existing refrigerators. The device 14 consumes very less power for operating thus making the solution economical and cost effective.

[0037] It should be understood that embodiments explained in the description above are only illustrative and do not limit the scope of this disclosure. Many such embodiments and other modifications and changes in the embodiment explained in the description are envisaged. The scope of the invention is only limited by the scope of the claims.

List of Reference Signs
10 household appliance
12 door
14 defrosting device
16 power detection unit
18 display unit
20 resistor circuit

, Claims:We Claim:
1. A household appliance (10), said appliance (10) comprising:
- a door (12) to access at least one item stored in said appliance (10);
characterized in that:
- a defrosting device (14) adapted to monitor a supply of power to said appliance (10) and adapted to adjust a defrost operating time based on said monitored power supply.

2. The appliance (10) as claimed in claim 1, wherein said defrosting device (14) adapted to monitor said power supply to said appliance (10) for a first predefined time and activates said defrost operation in said appliance (10) for a second predefined time in a normal cooling cycle of said appliance (10).

3. The appliance (10) as claimed in claim 1, wherein said defrosting device (14) adapted to adjust said defrost operating time by varying said second predefined time, if there is a disconnection of said power supply to said appliance (10) during said first predefined time.

4. The appliance (10) as claimed in claim 3, wherein said defrosting device (14) adapted to detect a drop in an electrical parameter in a power detection unit (16), when said disconnection of said power supply to said appliance (10) is occurred.

5. The appliance (10) as claimed in claim 4, wherein said power detection unit (16) is made as an integral part of said defrosting device (14) for monitoring said power supply to said appliance (10).

6. The appliance (10) as claimed in claim 1, wherein said defrosting device (14) is a chosen from a group of devices comprising a microprocessor, a micro controller, a digital circuit, an integrated chip and the like.

7. The appliance (10) as claimed in claim 1, wherein said defrosting device (14) is made operable on any one of means comprising a power supply and a battery.

8. The appliance (10) as claimed in claim 1, wherein said defrosting device (14) comprises a display unit (18) adapted to display an operating state of said appliance (10), wherein said operating state is chosen from any one of states comprising a normal working state and a defrost operation state.

9. A method of working of a defrosting device (14) in a household appliance (10), said method comprising:

- monitoring a supply of power to said household appliance (10) for a first predefined time by said defrosting device (14);
- activating a defrost operation in said appliance (10) for a second predefined time by said device (14), after completing said first predefined time;
- adjusting said second predefined time upon detecting a disconnection in said power supply to said appliance (10) in said first predefined time.

10. The method as claimed in claim 9, wherein detecting a drop in an electrical parameter in a power detection unit (16) in said defrosting device (14) when said disconnection of said power supply to said appliance (10) is occurred.