Household refrigeration appliance having a closed loop speed-controlled fan and method for operating a household refrigeration appliance having a closed-loop speed-controlled fan

Abstract

A household refrigeration appliance has a thermally-insulated body with an interior container that delimits a coolable interior space, a refrigeration circuit for cooling the coolable interior space and at least one fan. During the proper operation of the household refrigeration appliance, the fan is operated in a closed loop speed-controlled manner according to an at least indirectly specified desired rotational speed of the fan. During an inspection mode, the fan is operated without closed loop speed control, the actual rotational speed of the fan is ascertained and the actual rotational speed is evaluated in order to detect an abnormal operating state of the fan.

Claims

1. A method of operating a household refrigeration appliance that comprises a thermally-insulated body having an interior container that delimits an interior space, a refrigeration circuit for cooling the interior space, at least one fan, and an inverter operable with pulse-width modulation for controlling the fan, the method comprising the following method steps: during a regular operation of the household refrigeration appliance, operating the fan under closed loop speed control according to a specified desired rotational speed of the fan; during an inspection mode, operating the fan without closed loop speed control, ascertaining an actual rotational speed of the fan and evaluating the actual rotational speed with an electronic control unit of the household refrigeration appliance in order to detect an abnormal operating state of the fan; and operating the inverter during the inspection mode with a predetermined duty cycle that is allocated to the inspection mode.

2. The method according to claim 1, which comprises evaluating the actual rotational speed by comparing the actual rotational speed with a rotational speed of the fan to be expected for a normal operating state of the fan.

3. The method according to claim 1, wherein the refrigeration circuit comprises a compressor and a condenser, and the fan is provided to convey air that is warmed by the condenser into an environment of the household refrigeration appliance, and the abnormal operating state represents a contamination of the condenser and/or a failure of the fan, and the method comprises: detecting a contamination of the condenser and/or detecting a failure of the fan based on an evaluation of the actual rotational speed of the fan during the inspection mode; and based on the detected contamination of the condenser and/or based on the failure of the fan, operating the compressor in a gentle operating mode.

4. A household refrigeration appliance, comprising: a thermally-insulated body having an interior container that delimits a coolable interior space for storing foodstuffs; a refrigeration circuit for cooling the coolable interior space; and at least one fan; and wherein the household refrigeration appliance is configured to carry out the method according to claim 1.

5. A method of operating a household refrigeration appliance that comprises a thermally-insulated body having an interior container that delimits an interior space, a refrigeration circuit for cooling the interior space, and at least one fan, the method comprising the following method steps: during a regular operation of the household refrigeration appliance, operating the fan under closed loop speed control according to a specified desired rotational speed of the fan; during an inspection mode, operating the fan without closed loop speed control, ascertaining an actual rotational speed of the fan and evaluating the actual rotational speed with an electronic control unit of the household refrigeration appliance in order to detect an abnormal operating state of the fan; and operating the fan in the inspection mode for a predetermined period of time directly after starting up the fan from standstill and after an end of the predetermined time period operating the fan under closed loop speed control.

6. The method according to claim 5, which comprises starting up the fan from standstill during a start-up phase of the fan, and carrying out the start-up phase immediately prior to the inspection mode.

7. The method according to claim 5, wherein the household refrigeration appliance comprises an inverter operable with pulse-width modulation for controlling the fan, and the method further comprises operating the inverter during the inspection mode with a predetermined duty cycle that is allocated to the inspection mode.

8. The method according to claim 7, which comprises providing a closed loop controller to be controlled by the electronic control unit and configured to control the inverter and to operate the fan under closed loop speed control.

9. The method according to claim 8, which comprises causing the electronic control unit to specify to the closed loop controller the predetermined duty cycle that is allocated to the inspection mode, and deactivating the closed loop speed control of the fan that may be performed by the closed loop controller so that the fan is controlled by the inverter without closed loop speed control during the inspection mode.

10. A method of operating a household refrigeration appliance that comprises a thermally-insulated body having an interior container that delimits an interior space, a refrigeration circuit for cooling the interior space, at least one fan, and a duct system in which an evaporator of the refrigeration circuit and the fan are arranged and which is connected to the interior space, the method comprising the following method steps: during a regular operation of the household refrigeration appliance, operating the fan under closed loop speed control according to a specified desired rotational speed of the fan; during an inspection mode, operating the fan without closed loop speed control, ascertaining an actual rotational speed of the fan and evaluating the actual rotational speed with an electronic control unit of the household refrigeration appliance in order to detect an abnormal operating state of the fan; and causing the fan to convey air that is cooled by the evaporator from the duct system into the interior space and wherein the abnormal operating state of the fan represents an icing up of the evaporator.

11. The method according to claim 10, which comprises evaluating the actual rotational speed by comparing the actual rotational speed with a rotational speed of the fan that is to be expected for an evaporator that is not iced up and/or initiating a procedure of de-icing the evaporator on the basis of the evaluated actual rotational speed of the fan during the inspection mode.

12. The method according to claim 11, which comprises initiating the de-icing procedure if, during the inspection mode, the actual rotational speed exceeds a specified threshold value.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

(1) FIG. 1 is a perspective view of a household refrigeration appliance;

(2) FIG. 2 is a partial view of a duct system of the household refrigeration appliance;

(3) FIG. 3 is a partly schematic view of a closed loop speed-controlled fan of the household refrigeration appliance;

(4) FIG. 4 is a timing diagram that illustrates the operation of the fan;

(5) FIG. 5 is a similar diagram that illustrates the operation of the fan; and

(6) FIG. 6 is a schematic illustration of a compressor of a refrigeration circuit of the household refrigeration appliance.

DETAILED DESCRIPTION OF THE INVENTION

(7) Referring now to the figures of the drawing in detail and first, particularly, to FIG. 1 thereof, there is shown a perspective view of a household refrigeration appliance 1 that comprises a thermally-insulated body 2, also referred to as a housing or a carcass, with an interior container 3 that delimits a coolable interior space 4. The coolable interior space 4 is provided for storing foodstuffs.

(8) The household refrigeration appliance 1 comprises in the case of the present exemplary embodiment a door leaf 10 that is mounted on the body 2 in such a manner as to be able to pivot in particular with respect to a vertically extending axis. The coolable interior space 4 is accessible when the door leaf 10 is in the open state and the coolable interior space 4 is closed when the door leaf 10 is in the closed state.

(9) In the case of the present exemplary embodiment, multiple door trays 6 for storing foodstuffs are arranged on the side of the door leaf 10 that is facing the direction of the coolable interior space 4. In particular multiple compartment trays 7 for storing foodstuffs are arranged in the coolable interior space 4. A drawer 8 is arranged in the lower region of the coolable interior space 4. The drawer is likewise used for storing food. One of the compartment trays 7 that covers the upwardly positioned opening of the drawer 8 is arranged above the drawer 8.

(10) The household refrigeration appliance 1 comprises a refrigeration circuit 5 that is known in principle to those of skill in the art, for cooling the coolable interior space 4. With reference to FIG. 2, the refrigeration circuit 5 comprises inter alia an evaporator 20.

(11) The household refrigeration appliance 1 comprises in the case of the present exemplary embodiment an electronic control unit 9 that is configured so as to control the refrigeration circuit 5 such that the coolable interior space 4 assumes at least approximately a specified desired temperature or a desired temperature that may be specified. The electronic control unit 9 is preferably configured in such a manner that it controls the temperature of the coolable interior space 4 in a closed-loop manner. In order where appropriate to obtain the actual temperature of the coolable interior space 4, the household refrigeration appliance 1 may comprise at least one temperature sensor (not illustrated in detail) connected to the electronic control unit 9.

(12) With reference to FIG. 2, the household refrigeration appliance 1 comprises a duct system 21 that is arranged in particular within the thermally-insulated body 2 and is connected to the coolable interior space 4 via an opening 11. The evaporator 20 is arranged in the duct system 21.

(13) A fan 22 is arranged in the duct system 21. The fan 22 is provided, in its activated state, to convey air that is cooled by the evaporator 20 into the coolable interior space 4 via the duct system 21 and via the opening 11.

(14) The fan 22 comprises an electric motor 23 and a fan wheel 24 that may be rotated by means of the motor 23 (FIG. 3).

(15) The household refrigeration appliance 1 is configured so as, during the proper operation of said household refrigeration appliance, to operate the fan 22 in a closed loop speed-controlled manner according to a desired rotational speed n.sub.desired that is specified at least indirectly by the electronic control unit 9, and during an inspection mode to operate the fan in a manner without closed loop speed control, to ascertain the actual rotational speed n.sub.actual of the fan 22 and to evaluate the actual rotational speed by means of the electronic control unit 9 in order to detect an abnormal operating state of the fan 22, in particular to detect an icing-up of the evaporator 20.

(16) In order to determine the actual rotational speed n.sub.actual of the fan 22, the household refrigeration appliance 1 comprises in the case of the present exemplary embodiment a tachometer 33 that measures the actual rotational speed n.sub.actual of the fan 22 or rather of its fan wheel 24. The output signal of the tachometer 33 that comprises information relating to the actual rotational speed is supplied inter alia for evaluating purposes to the electronic control device 9.

(17) The household refrigeration appliance 1 comprises in the case of the present exemplary embodiment an inverter 31 that has pulse-width modulation and is provided so as to control the fan 22. The inverter 31 is operated in particular during the inspection mode with a predetermined duty cycle that is allocated to the inspection mode.

(18) In the exemplary embodiment, the household refrigeration appliance 1 comprises a closed loop controller 32 that is controlled by the electronic control unit 9 and is provided so as control the inverter 31 and to operate the fan 22 in a closed loop speed-controlled manner. The electronic control unit 9 supplies for example to the closed loop controller 32 information as to whether the fan 22 is to be operated in the closed loop speed-controlled operation or for the inspection mode is to be operated in the operation without closed loop speed control and information relating to the desired rotational speed n.sub.desired of the fan 22.

(19) In the case of the present exemplary embodiment, the actual rotational speed n.sub.actual is evaluated during the inspection mode by comparing the actual rotational speed with a rotational speed of the fan 22 that is to be expected for the evaporator 20 that has not iced-up and/or for a fan 22 that is not defective in general for a normal operating state of the fan 22. On the basis of the evaluated actual rotational speed of the fan 22 during the inspection mode, it is possible to initiate a procedure of de-icing the evaporator 20, in that for example the electronic control unit 9 switches on a heating device so as to de-ice the evaporator after the prevailing cooling phase. The procedure of de-icing the evaporator 20 may then be initiated for example if the actual rotational speed exceeds a specified threshold value during the inspection mode.

(20) In accordance with an embodiment illustrated in FIG. 4, it is provided by means of the electronic control unit 9 specifying to the closed loop controller 32 the predetermined duty cycle DC that is allocated to the inspection mode to deactivate the closed loop speed control of the fan that may be performed by the closed loop controller 32 so that the fan 22 is controlled by the inverter 31 in a manner without closed loop speed control during the inspection mode. The prevailing duty cycle DC of the inverter 31 is then the predetermined duty cycle that is allocated to the inspection mode. For the closed loop speed-controlled operation of the fan 22 in the case of the present exemplary embodiment, the electronic control unit 9 supplies to the closed loop controller 32 a different duty cycle to the predetermined duty cycle that is allocated to the inspection mode, said different duty cycle comprising information relating to the desired rotational speed of the fan 22 during the closed loop speed-controlled operation.

(21) Referring now to FIG. 4, in the case of this exemplary embodiment, a supply voltage V is switched on for the inverter 31 at the point in time t.sub.0.

(22) From the point in time t.sub.1 to the point in time t.sub.2, the fan 22 is started up from standstill during a start-up phase. During this start-up phase, the fan 22 may be operated in a closed loop speed-controlled manner or in a manner without closed loop speed control.

(23) From the point in time t.sub.2 onwards, the electronic control unit 9 supplies to the closed loop controller 32 the predetermined duty cycle that is allocated to the inspection mode, said duty cycle being for example 50%. Subsequently, the closed loop controller 32 or the closed loop function of the closed loop control is deactivated with the result that the fan 22 is operated in a manner without closed loop speed control.

(24) As long as the predetermined duty cycle that is allocated to the inspection mode is available at the closed loop controller 32, the rotational speed of the fan 22 is not controlled in a closed loop manner and after a relatively short settling time period may be compared with the desired rotational speed that is allocated to the evaporator 20 that is not iced-up. If the analysis of the actual rotational speed and consequently of the fan 22 is completed at the point in time t3, the electronic control unit 9 transmits to the closed loop controller 32 a duty cycle DC that differs from the predetermined duty cycle that is allocated to the inspection mode, as a result of which the fan 22 is operated in a closed loop speed-controlled manner at a rotational speed that is allocated to the selected duty cycle.

(25) At the point in time t.sub.4 in the case of the present exemplary embodiment, the duty cycle is set to 0% in order to slow the fan 22 down to standstill. The supply voltage V of the inverter is switched off at the point in time t.sub.5.

(26) In accordance with an embodiment illustrated in FIG. 5, it is provided that directly after the fan 22 has been started up from standstill, the fan 22 is operated initially for a predetermined period of time T.sub.v in the inspection mode in a manner without closed loop speed control and after the end of the predetermined time period T.sub.v said fan is operated in a closed loop speed-controlled manner. Where appropriate, it is also possible to provide a start-up phase of the fan 22 from standstill directly prior to the inspection mode, the start-up phase being performed in a manner without closed loop speed control or in a closed loop speed-controlled manner.

(27) At the point in time t.sub.0 in the case of this exemplary embodiment, the supply voltage V for the inverter 31 is switched on.

(28) At the point in time t.sub.1, the start-up phase of the fan 22 commences and ends at the point in time t.sub.2. The duration of the start-up phase may be for example fixedly specified or may end upon a predetermined actual rotational speed of the fan 22 being achieved.

(29) At the point in time t.sub.2, the start-up phase ends and the inspection mode commences automatically for the predetermined time period T.sub.v that ends at the point in time t.sub.3. The closed loop speed control function is deactivated during the inspection mode with the result that after a settling time period the actual rotational speed of the fan 22 is compared with its desired rotational speed. After the specified time period Tv, the analysis of the actual rotational speed n.sub.actual and consequently of the fan 22 is completed and the closed loop speed-control function re-activated at the point in time t3.

(30) At the point in time t.sub.4 in the case of the present exemplary embodiment, the desired rotational speed is set to 0 in order for example to slow the fan 22 down in a closed loop speed-controlled manner to standstill. The supply voltage V of the inverter is switched off at the point in time t.sub.5.

(31) The refrigeration circuit of the household refrigeration appliance 1 comprises a compressor 60 that is illustrated in FIG. 6 and a condenser 62, that are arranged for example in a machine space 61 that is located to the rear of the drawer 8.

(32) The abnormal operating state of the fan 22 may also be a failure of the fan 22.

(33) The fan 22 may be provided for example so as to convey air that is warmed by the condenser 62 into the environment of the household refrigeration appliance 1. It is then possible to provide that on the basis of a detected failure of this fan 22 the compressor 60 is operated in a gentle operating mode. The compressor 60 is for example a closed loop speed-controlled compressor. A gentle operating mode, by way of example, is an operation of the compressor 60 at a lower rotational speed.

(34) The condenser that is configured in particular as a roll or lamella condenser may become contaminated, for example during operation. It is possible to detect this in the case of the present exemplary embodiment by evaluating the actual rotational speed of the fan 22 during the inspection mode. In the case of a detected contamination of the condenser, it may then be provided to operate the compressor 60 in the gentle operating mode controlled by means of the electronic control unit 9.

(35) The following is a summary list of reference numerals and the corresponding structure used in the above description of the invention: 1 Household refrigeration appliance 2 Body, housing 3 Interior container 4 Coolable interior space 5 Refrigeration circuit 6 Door tray 7 Compartment trays 8 Drawer 9 Electronic control unit 10 Door leaf 11 Opening 20 Evaporator 21 Duct system 22 Fan 23 Motor 24 Fan 31 Inverter 32 Closed loop controller 33 Tachometer 60 Compressor 61 Machine space 62 Condenser n.sub.actual Actual rotational speed n.sub.desired Desired rotational speed DC Duty Cycle Tv Predetermined time period V Supply voltage t.sub.1-t.sub.5 Point in time