REFRIGERATOR WITH ADVANCED NO-FROST OPERATION

Abstract

 The present invention refers to a refrigerator (1). The refrigerator (1) according to the present invention comprises at least
a compressor unit (2) for compressing a liquid,
a heater unit (4) for heating of at least parts of an internal space for defrosting,
an energy source (5), in particularly a plug for connecting to a grid,
wherein the energy source (5) provides electric energy for operating the heater unit (4) and
wherein the energy source (5) provides an operating current for operating the compressor unit (2),
and
a control unit (3),
wherein the control unit (3) determines changes of the operating current of the compressor unit (2),
wherein the control unit (3) operates the heater unit (4) in a predefined manner in dependency of changes of the operating current.

Description

[0001] The present invention refers according to claim 1 to a refrigerator and a method for operating a refrigerator according to claim 10.

Background of the Invention

[0002] In all no-frost refrigerators, there is a heater on the heat-exchanger for prevent icing. After starting of refrigerator, heat-exchanger starts cooling and icing. This is unwelcome situation by user and inefficient situation by cooling performance of refrigerator. So, there is located a heater on the heat-exchanger in all no-frost refrigerators to prevent icing. After a long certain time (8-12 hours) starting of the refrigerator, the heater works a small certain time (5-10 minutes) for to melt the ice. This operation is called as defrost.

[0003] Document US5692385A discloses an apparatus for use with a refrigeration system including a compressor for compressing a working fluid evaporated in an evaporator and condensed in a condenser. A control circuit initiates operation of a refrigeration cycle and initiates a defrost cycle in response to a defrost enable signal. The apparatus drives an air moving assembly moving air over the evaporator. A motor including a rotatable assembly is in driving relation to the air moving assembly. An energizing circuit selectively energizes the motor in response to the control circuit. A sensing circuit generates a speed/torque signal representative of a speed or a torque of the motor. A defrost initiating circuit generates the defrost enable signal when the speed/torque signal indicates that the speed is greater than a predetermined speed or the torque is greater than a predetermined torque. As a result, the defrost cycle is initiated in response to degradation of the refrigeration cycle as indicated by frost or ice on the evaporator which reduces air flow through the evaporator and increases static pressure. Other demand defrost apparatus and methods of initiating and sensing defrost cycles are also disclosed.

[0004] Document US20080073376A1 discloses a dispenser, for preferably Frozen Carbonate Beverage (FCB) product, having valves that can be manually or electrically operated in response to electronic controls. The valve has a jam dispensing position, and can be used with an additive, such as flavors, injector. A power failure back up is provided to close the valve, along with sanitation and optional purging cycles. Product dispense is provided only when sensed to have a desired consistency and/or in a condition to prevent splashing. Additive dispense is provided only when product is present. The dispenser can have a monitor and suitable controller to dispense strips or layers of different additives or flavors into the product.

[0005] Document US20110079027A1 discloses an embodiment of a probe, which includes a sensor and a support. The sensor is operable to provide an indication of a thickness of a frozen substance that has accumulated between the sensor and a cooling fin of a cooling unit, and the support is operable to hold the sensor spaced apart from the cooling fin. For example, a defrost controller may use an embodiment of such a probe to monitor an amount of frost build up on the fin or fins of a cooling unit (e.g., a refrigeration or freezer unit) so that the controller may initiate a defrost cycle only when warranted. Such a probe may be more reliable than other defrost-detection techniques, and such a defrost controller may increase the cooling and energy efficiencies of a cooling unit as compared to a cooling unit having a conventional defrost controller.

[0006] Document US4104888 discloses a control system for monitoring frost accumulation on the coil of a heat pump. An operational parameter of the heat pump compressor responsive to frost accumulation, such as compressor current, is compared to a reference level developed during a non-frost condition of the coil to initiate and terminate coil defrosting in response to a predetermined variation between the operational and reference parameter levels.

[0007] Thus, the main problem is that the presence and amount of ice on the heat-exchanger is not detected simultaneously without sensors. Defrost operation is done automatically with help of periodic programming. Existence of ice and need of heating to melt the ice is unknown. So this periodic defrost operation causes inefficient situation by energy consume and cooling performance of No-frost refrigerators.

Object of the Invention

[0008] Therefore, it is the object of the present invention to provide an advanced refrigerator that requires less electronic parts and enables the reduction of energy losses.

Description of the Invention

[0009] The before mentioned object is solved by a refrigerator according to claim 1. The refrigerator according to the present invention comprises at least a compressor unit for compressing a liquid, a heater unit for heating of at least parts of an internal space for defrosting,
an energy source, in particularly a plug for connecting to a grid, wherein the energy source provides electric energy for operating the heater unit and wherein the energy source provides an operating current for operating the compressor unit, and a control unit, wherein the control unit determines changes of the operating current of the compressor unit, wherein the control unit operates the heater unit in a predefined manner in dependency of changes of the operating current. The compressor unit preferably comprises or consist of a BLDC compressor.

[0010] This solution is advantageous, since the heater unit on the heat-exchanger does not work in unnecessary conditions. This provides a better energy efficiency and improves the cooling performance of No-frost refrigerators, in particularly of those having a BLDC compressor. This solution does not effected environment disturbances and is more reliable than using sensors. Thus, there is no need for any defrost sensor or additional defrost material.

[0011] Further preferred embodiment are described in the following description parts and/or are subject-matter of the dependent claims.

[0012] The operating current is detected according to a preferred embodiment of the present invention in multiple predefined time intervals and an output value representing the average current in each time interval is outputted, wherein the output values are processed as matrix values, wherein the output values are inputted into a state matrix one after the other, wherein a determinant is calculated and outputted after the state matrix is filled. This embodiment is beneficial since changes of the operating current are tracked and processed in a predefined manner.

[0013] According to a further preferred embodiment of the present invention further output values representing the average operating current in defined time intervals are outputted, wherein the output values are processed as further matrices values, wherein the output values are inputted into further state matrixes one after the other, wherein the output values of each time interval are processed as one state matrix, wherein a determinant is calculated and outputted for each state matrix. This embodiment is beneficial since a very precise determination and handling of present situations is possible.

[0014] An ice level matrix is set up according to a further preferred embodiment of the present invention, wherein the ice level matrix is a YxY matrix, in particularly a 2x2 matrix, wherein the determinants are inserted in chronological order. This embodiment is beneficial since the determinants of the individual matrices are processed in such a manner that information about the present icing situation can be derived easily.

[0015] In case the ice level matrix is full a further determinant is according to a further preferred embodiment of the present invention inserted into the field of the last line and the last column, the determinant of the filed in the first line and the first column is deleted, each of the other determinants is inserted into a field previous to the respective present field.

[0016] According to a further preferred embodiment of the present invention zero ice level is determined in case all four members of ice level matrix are negative, low ice level is determined in case three members of ice level matrix are negative, mid ice level is determined in case two members of ice level matrix are negative, high ice level is determined in case one members of ice level matrix is negative, highest ice level is determined in case zero members of ice level matrix are negative, wherein zero ice level does not require operation of heater unit and wherein low ice level requires a first time interval of operating the heater unit, wherein mid ice level requires a second time interval of operating the heater unit, wherein high ice level requires a third time interval of operating the heater unit, wherein highest ice level requires a fourth time interval of operating the heater unit, wherein the second time interval is longer than the first time interval and wherein the third time interval is longer than the second time interval and wherein the fourth time interval is longer than the third time interval. This embodiment is beneficial since the necessary heater unit operation can be selected in a clear and precise manner.

[0017] The above mentioned object is also solved by a method according to claim 10 for operating a refrigerator. The inventive method comprises at least the steps: Providing a refrigerator, wherein the refrigerator comprises at least a compressor unit for compressing a liquid, a heater unit for heating of at least parts of an internal space for defrosting, an energy source, in particularly a plug for connecting to a grid, wherein the energy source provides electric energy for operating the heater unit and wherein the energy source provides an operating current for operating the compressor unit, and a control unit, wherein the control unit determines changes of the operating current of the compressor unit, wherein the control unit operates the heater unit in a predefined manner in dependency of changes of the operating current; Detecting the operating current; Operating the heater unit in dependency of the detected operating current.

[0018] Further benefits, goals and features of the present invention will be described by the following specification of the attached figure, in which exemplarily components of the invention are illustrated. Components of the device and methods according to the invention, which match at least essentially with respect to their function can be marked with the same reference sign, wherein such components do not have to be marked or described multiple times with respect to said figure. In the following the invention is just exemplarily described with respect to the attached figure.

Brief Description of the Drawing

[0019] 

Fig. 1

shows a refrigerator comprising a BLDC compressor and a control unit.

[0020] Fig. 1 shows a refrigerator 1. Said refrigerator 1 comprises a BLDC compressor 2. The BLDC compressor is part of a heat-exchanger unit. In case ice and/or snow are growing the operating current for operating the compressor 2 changes. In dependency of such changes a control unit 3 operates a heater unit 4.

[0021] Thus, the present invention refers to a compressor unit 2 for compressing a liquid, a heater unit 4 for heating of at least parts of an internal space for defrosting, an energy source 5, in particularly a plug for connecting to a grid, wherein the energy source 5 provides electric energy for operating the heater unit 4 and wherein the energy source 5 provides an operating current for operating the compressor unit 2, and a control unit 3, wherein the control unit 3 determines changes of the operating current of the compressor unit 2, wherein the control unit 3 operates the heater unit 4 in a predefined manner in dependency of changes of the operating current.

[0022] Therefore, preferably no sensor for detecting ice or snow on heat-exchanger is present. The inventive refrigerator 1 preferably has a BLDC compressor (inverter). There are two current components of BLDC compressor as Id and Iq. Id is the flux component and Iq is the torque component of the BLDC compressor current. The average of the torque component of the BLDC compressor current (Iq) is taken in certain measurement period. After starting of refrigerator 1, the heat-exchanger cools and there is snowing or icing on heat-exchanger. The amount of the snow or ice on the heat-exchanger is preferably relative with average on the heat-exchanger, the Iq value decreases simultaneously. Because of the icing on the heat-exchanger, need of BLDC compressor torque decreases. The average measurements Iq values are captured in period of small certain time (interval between 5 and 10 minutes can be select) for a newly developed matrices algorithm. The detecting existing ice even amount of the ice on the heat-exchanger without using any sensor but with using a matrix algorithm is possible.

[0023] The average value of Iq values preferably creates a state matrix as below:

[0024] After that the determinant of this state matrix is taken and an Ice Level Matrix is created preferably as below :

[0025] The critical point is, when the Ice or snow does not occur on the heat-exchanger, the IqN, ave values decrease regularly (Iq1, ave > Iq2, ave > Iq3, ave > Iq4, ave) (N = 1,2,3 ...).
At this condition, det (state matrix_N) is always equal to negative value.
When the Ice or snow occurs on the heat-exchanger, the IqN, ave values decrease regularly and be stable (Iq1, ave ≥ Iq2, ave ≅ Iq3, ave ≅ Iq4, ave) (N = 1,2,3 ...).
At this condition, det (state matrix_N) is always equal to zero or positive value.

[0026] In conclusion, number of positive-negative value Ice Level Matrix members give the ice or snow level.

[0027] One interpretation of the Ice Level matrix might be:

* 4 members of Ice Level Matrix is negative = zero ice level (no need defrost)

* 3 members of Ice Level Matrix is negative = low ice level (short time defrost)

* 2 members of Ice Level Matrix is negative = mid ice level (mid time defrost)

* 1 members of Ice Level Matrix is negative = high ice level (long time defrost)

* 0 members of Ice Level Matrix is negative = highest ice level (longest time defrost)

[0028] The heater unit is preferably operated in dependency of the number of members of the Ice Level Matric.

[0029] In particular, the present invention refers to a refrigerator 1 which comprises at least
a compressor unit 2 for compressing a liquid, a heater unit 4 for heating of at least parts of an internal space for defrosting, an energy source 5, in particularly a plug for connecting to a grid, wherein the energy source 5 provides electric energy for operating the heater unit 4 and wherein the energy source 5 provides an operating current for operating the compressor unit 2, and a control unit 3, wherein the control unit 3 determines changes of the operating current of the compressor unit 2, wherein the control unit 3 operates the heater unit 4 in a predefined manner in dependency of changes of the operating current.

List of reference numbers

[0030] 

1

refrigerator

2

BLDC compressor

3

control unit

4

heater unit

5

energy source

Claims

1. Refrigerator (1),
at least comprising
a compressor unit (2) for compressing a liquid,
a heater unit (4) for heating of at least parts of an internal space for defrosting,
an energy source (5), in particularly a plug for connecting to a grid,
wherein the energy source (5) provides electric energy for operating the heater unit (4) and wherein the energy source (5) provides an operating current for operating the compressor unit (2),
and
a control unit (3),
wherein the control unit (3) determines changes of the operating current of the compressor unit (2),
wherein the control unit (3) operates the heater unit (4) in a predefined manner in dependency of changes of the operating current.

2. Refrigerator according to claim 1,
characterized in that
the compressor unit (2) comprises or consist of a BLDC compressor.

3. Refrigerator according to claim 1 or 2,
characterized in that
operating current is detected in multiple predefined time intervals and an output value representing the average current in each time interval is outputted, wherein the output values are processed as matrix values, wherein the output values are inputted into a state matrix one after the other,
wherein a determinant is calculated and outputted after the state matrix is filled.

4. Refrigerator according to claim 3
characterized in that
further output values representing the average operating current in defined time intervals are outputted, wherein the output values are processed as further matrices values, wherein the output values are inputted into further state matrixes one after the other, wherein the output values of each time interval are processed as one state matrix,
wherein a determinant is calculated and outputted for each state matrix.

5. Refrigerator according to claim 4,
characterized in that
an ice level matrix is set up, wherein the ice level matrix is a YxY matrix, wherein the determinants are inserted in chronological order.

6. Refrigerator according to claim 5,
characterized in that
in case the ice level matrix is full a further determinant is inserted into the field of last line and last column, the determinant of the filed in first line and first column is deleted, each of the other determinants is inserted into a field before the respective present field.

7. Refrigerator according to claim 6,
characterized in that
the ice level matrix is a 2x2 matrix.

8. Refrigerator according to claim 7,
characterized in that
zero ice level is determined in case all four members of ice level matrix are negative,
low ice level is determined in case three members of ice level matrix are negative,
mid ice level is determined in case two members of ice level matrix are negative,
high ice level is determined in case one members of ice level matrix is negative,
highest ice level is determined in case zero members of ice level matrix are negative, wherein zero ice level does not require operation of heater unit and
wherein low ice level requires a first time interval of operating the heater unit,
wherein mid ice level requires a second time interval of operating the heater unit, wherein high ice level requires a third time interval of operating the heater unit,
wherein highest ice level requires a fourth time interval of operating the heater unit, wherein the second time interval is longer than the first time interval and wherein the third time interval is longer than the second time interval and wherein the fourth time interval is longer than the third time interval.

9. Refrigerator according to any of claims 3 to 8,
characterized in that
each state matrix is a 2X2 matrix.

10. Method for operating a refrigerator
at least comprising the steps:

providing a refrigerator (1) at least comprising

a compressor unit (2) for compressing a liquid,

a heater unit (4) for heating of at least parts of an internal space for defrosting,

an energy source (5), in particularly a plug for connecting to a grid,

wherein the energy source (5) provides electric energy for operating the heater unit (4) and

wherein the energy source (5) provides an operating current for operating the compressor unit (2),

and

a control unit (3),

wherein the control unit (3) determines changes of the operating current of the compressor unit (2),

wherein the control unit (3) operates the heater unit (4) in a predefined manner in dependency of changes of the operating current,

detecting the operating current,

operating the heater unit (4) in dependency of the detected operating current.

Drawing