DE102009046084A1 - Household appliance, in particular dishwasher - Google Patents

Abstract

The invention relates to a household appliance, in particular a dishwasher, with at least one appliance component (23, 24, 25) which can be supplied with electrical current via a working line (30) and a monitoring unit (32) with which a through the working line (30) flowing fault current can be detected in at least one fault case. According to the invention, current flowing to the device component (23, 24, 25) and a current flowing away from it can be detected by means of the monitoring unit (32).

Description

The invention relates to a domestic appliance, in particular a dishwasher, with at least one device component which can be supplied with electrical power via a working line, and a monitoring unit with which a residual current flowing through the working line in the event of a fault can be detected.

As is known, device components, such as an inlet valve, a regeneration valve and / or a water diverter, are connected in the rinsing fluid circuit of a dishwasher. These may comprise electromagnetically operable actuators or actuators, which are controllable by means of a control device and can be supplied with electrical current via a working line. For this purpose, a control element is associated with each actuator, which is arranged in the leading to the actuator working line and can be controlled by the control device. In the closed position of the drive element, the power supply to the actuator is interrupted, while in the open position of the drive element, the power supply to the actuator is released. The drive element of the actuator can be a triac, a relay, a transistor or a mosfet.

In the case of the inlet valve, the regeneration valve or the water diverter their actuators during a rinse cycle in total only over a period of a few minutes in operation. For reasons of reliability, however, these actuators are designed for continuous operation. Such a continuous operation of the actuator would result in an error case in which the triac is defective and therefore permanently conductive. In this case, the associated actuator would be permanently activated. The actuators are therefore far oversized for normal operation in which they are only briefly in operation.

For household appliances, such as the above-mentioned dishwasher, different error cases can occur. Thus, one of the drive elements can burn out, as a result of which it becomes permanently conductive. In this case, the actuator associated with the defective control element would operate in an impermissible manner in continuous operation.

In a further error case impermissible leakage currents can occur in the household appliance. Such an error case can be in one, from the DE 101 63 197 A1 known generic household appliance can be detected by means of a monitoring unit. With the aid of the monitoring unit, initially a desired value of a permissible current consumption of the at least one device component is set. In addition, an actual value of the device component or the household appliance is measured and compared with the corresponding desired value. If the setpoint value is exceeded, a safety measure is triggered.

From the EP 1 021 123 B1 and from the EP 1 269 906 A1 Another household appliance is known which has a heating element. The heating element is connected via a mains phase conductor and a neutral conductor to a power supply network. In the circuit there is provided a differential current transformer which generates a voltage in a winding when there is a current in the network phase conductor and the neutral conductor which is asymmetrical. If the generated voltage exceeds a predetermined value, the current flow to the heating element is interrupted.

The object of the invention is to provide a household appliance, in particular a dishwasher, in which the reliability is ensured in a simple and reliable manner.

According to the invention, a current flowing to the device component and a current flowing therefrom can be detected by means of the monitoring unit. Thus, with the monitoring unit different error cases can be detected, and there are extended diagnostic possibilities, since by detecting the inflowing and outflowing current and in relation to each other a fault diagnosis is made possible, for example. Whether there is a short circuit of a power element and / or a leakage current in the management is present.

In a preferred embodiment, it is provided that the difference between the inflowing and outflowing flow can be evaluated to detect the fault. Thus, it is also possible in a simple manner to check whether an error situation is caused by a ground fault, which results in a difference between incoming and outgoing current. Furthermore, it is possible to detect electrical currents coupled into the working line in the event of a fault.

In a simple embodiment, the monitoring unit may comprise a first and a second current measuring device, which is connected in a series circuit in the working line before and after the at least one device component. By means of the two current measuring devices, a differential current measurement can be carried out, in which the difference between incoming and outgoing current is detected. Upon detection of such a difference, a fault current or leakage current can be detected.

The current measuring devices can be exemplary measuring shunts with which the current flow is detected by the work line or by the device component. The detected differential current can be compared with a threshold value for a function and plausibility check. The size of the threshold value can vary depending on the respective operating states of the device component to be tested. When using a shunt, the voltage drop can be detected on a measuring resistor connected to the working line. Such a voltage drop is detected if current flows through the measuring resistor.

As an alternative to the error case specified above, the monitoring unit can also be used to monitor the function of the activation element of the respective actuator. In this case, it is checked whether the drive element is open and can be controlled without errors or is impermissibly permanently conducting current, as is the case with a blown drive element.

In order to detect such an error, the monitoring unit can record an electrical current in a working line of the device component when the activation element is not activated and compare it with a threshold value. On the basis of this comparison, the defect state of the drive element can be seen.

If such a defect state of the drive element is detected, appropriate measures can be taken to interrupt a power supply to the at least one associated device component. Since, according to the invention, a faulty actuator can be detected, therefore, the associated device component no longer has to be designed for continuous operation, as is the case without such a monitoring unit. With such a function monitoring, the monitoring unit can thus use a voltage or current measurement to detect whether the activation element is conductive or non-conductive.

The drive element of the device component can be a control, for example a triac, a transistor or a mosfet, which can be switched between a current-conducting closed position and an open position.

In one embodiment, the control device - in addition to the drive element of the device component - be associated with an additional shutdown element, such as a relay or a semiconductor. With the additional shutdown element, the control device can interrupt or release a power supply to the device component independently of a switching position of the drive element.

This may be particularly advantageous in the case of the above-mentioned error, in which the drive element of the device component is defective and is improperly permanently in a current-conducting closed position, in which it can no longer be actuated by the control device. In this case, the already mentioned, disadvantageous continuous activation of the device component would result. Such continuous activation can be avoided by interrupting the power supply to the device component with the aid of the additional shutdown element. With the additional shutdown a permanent control is thus excluded. The device components or their actuators therefore do not have to be costly designed for this fault.

Preferably, two or more device components are provided in the working line. Their control elements can be in signal connection with the control device. The device components may be connected in parallel to each other in sub-lines of the working line, each device component may be assigned a control element. In this case, the plurality of device components may preferably be assigned a common switch-off element. The turn-off element can in particular be connected in series with the device components connected in parallel.

In addition, a pulse width modulation can be used in the power supply of the device component. As a result, regardless of network fluctuations, the electrical energy conducted to the device component can be kept constant.

For such a pulse width modulation, a rectifier can be connected in the circuit of the device component, which rectifies the mains voltage. At the same time, the control device can control the abovementioned shutdown element or the control element clocked in an adjustable duty cycle. The duty cycle may be in particular in a frequency range greater than 1000 Hz, preferably greater than audible frequencies, that is greater than 10 to 12 kHz. In case of a fluctuation of the mains voltage, the duty cycle of the shutdown element or the control element can be varied such that an arithmetically averaged voltage is applied to the device component, which corresponds approximately to the voltage to which the device component is designed.

With the above-mentioned pulse width modulation thus the device component can be used regardless of the size of the mains voltage. For example, in the case of a mains voltage of 230 V (AC voltage) with direct rectification of the mains voltage DC voltage of 320 V are generated. The DC voltage can be clocked by the shutdown element or the control element, for example, in a duty cycle of 50:50 as well as in a predetermined switching frequency. In this way, an arithmetically averaged DC voltage of 160 V is applied to the device component. With a changed mains voltage, the clock ratio can be changed in such a way that in turn an arithmetically averaged DC voltage of 160 V can be set on the device component. A device component designed for 160 V can thus be used for varying mains voltages.

In the following, two embodiments of the invention will be described with reference to the attached figures. Show it:

1 in a schematic block diagram, a dishwasher;

2 a circuit diagram according to the first embodiment; and

3 a circuit diagram according to the second embodiment.

In the 1 is roughly schematically a dishwasher with a, a washing compartment limiting washing compartment 1 shown. In a sump 3 of the washing container 1 opens a fresh water supply 5 in which an inlet valve 7 is switched. The sump 3 is also via a recirculation line 9 with a circulation pump 13 in conjunction, which flushes the water through a water heater 14 as well as a water switch 15 either to spray arms 16 in the washing compartment of the washing container 1 or to a fleet store 17 leads, can be cached in the rinse liquid. The device components switched into the liquid circuit of the dishwasher, for example the inlet valve 7 , the circulation pump 13 or the water switch 15 , are via signal lines 19 from a controller 21 controllable.

On the basis of in the 2 The circuit diagram shows the power supply of the device components as well as their control. Exemplary are in the 2 the actuators or actuators 23 . 24 . 25 shown, with whose help the inlet valve 7 , the water switch 15 or other device components, such as a Regenerierventil not shown in detail, are actuated. The actors 23 . 24 . 25 are connected via a working line connected to the power supply network 30 supplied with electrical energy. The actors 23 . 24 . 25 are in parallel sub-lines 30a . 30b . 30c the work management 30 connected. Each of the actors 23 to 25 is in each case a drive element 26 . 27 . 28 connected in series.

The control elements 26 . 27 . 28 In the application shown, triacs are connected via the signal lines 19 by means of the control device 21 are controllable. In series with the three parallel actuators 23 to 25 is a shutdown element 29 in the work management 30 arranged, which also has a signal line 19 with the control device 21 is coupled. The shutdown element 29 is in its electrically conductive closed position during a purge cycle and, as described later, provides a second shutdown path.

The mutually parallel sub-lines 30a . 30b . 30c is in the work line in each case a first and a second measuring shunt 31 a monitoring unit 32 upstream and downstream.

With the monitoring unit 32 can by the work management 30 or by the device components 23 . 24 . 25 flowing electrical current are detected. The detected current may be in an evaluation device of the monitoring unit 32 be compared with a threshold. As a result, different error cases, that is to say defect states of actuators or leakage currents, can be detected, as described later.

During a rinse cycle of the dishwasher are the actuators 23 . 24 . 25 temporarily in operation, that is with a certain pulse-pause ratio or only for a short time. The actors 23 . 24 . 25 can have electromagnetic coils, for example, which activates a valve stem of the inlet valve 7 or the regeneration valve to move a valve lift. For this purpose, the control device controls 21 an example of the triac 26 on, causing the actor 23 is supplied with electrical energy. Subsequently, the triac 26 be re-energized, reducing the power supply to the actuator 23 is interrupted.

In device operation, for example, the triac 26 run away. In case of defective triac 26 this can be permanently in a current-conducting closed position, whereby the actuator 23 permanently, that is also in the non-energized state, is energized. This error case is made by means of the monitoring unit 32 recognized. The monitoring unit compares this 32 from the first measurement shunt 31 measured current with the threshold value corresponding to a predetermined target current. The above-mentioned error case is detected by a deviation of the actually measured current from this target current.

If an error occurs, the monitoring unit initiates 32 an interference signal to the control device 21 , The controller then opens 21 the shutdown element 29 , which reduces the power supply to the actuators 23 to 25 is interrupted. At the same time, the control device 21 a visual warning display 22 activate.

By means of the monitoring unit 32 In addition, the device safety with regard to fault current safety can be improved. So can by means of the two measuring shunts 31 a differential current measurement takes place, in which one to the actuators 23 to 25 flowing current and an outgoing current is detected. On the evaluation of the detected differential current, another error case can be detected, in which a fault current through the working line 30 flows or a leakage current occurs. If such an error is detected, then the control device 21 the actors 23 to 25 switch off and / or generate an error display.

In the 3 a circuit diagram is shown according to the second embodiment, in which additionally a pulse width modulation is used, with the independent of mains fluctuations, the respective actuator 23 to 25 guided electrical voltage remains constant. For this purpose, the monitoring unit 32 a rectifier 33 upstream, with which the mains voltage is converted into a DC voltage. In addition, it is in parallel with the actuators 23 to 25 a freewheeling diode 34 intended to protect against overvoltage.

The shutdown element 29 is according to the 2 in normal operation is not constant in its closed position, but is clocked in a predetermined duty cycle and at a given switching frequency. The duty cycle is thereby by the controller 21 set such that an arithmetically averaged voltage is generated at the actuators 23 to 25 is applied and corresponds approximately to a voltage to which the respective actuators 23 to 25 are designed.

By way of example, at a first mains voltage of 230 V (AC voltage) by means of the rectifier 33 a DC voltage of 320 V are generated. At a duty cycle of the shutdown 29 of 50:50 can thus result in an arithmetically averaged DC voltage of 160 V, the at the actuators 23 . 24 . 25 is applied.

If now the dishwasher is applied to a power supply network with reduced or increased mains voltage, then the duty cycle starting from 50:50 can also be adjusted so that again sets an arithmetically averaged DC voltage of 160 V, the actuators 23 . 24 . 25 is applied.

LIST OF REFERENCE NUMBERS

1

rinse tank

3

sump

5

supply line

7

inlet valve

9

circulation line

13

circulating pump

14

water Heating

15

water points

16

spray arms

17

fleet memory

19

signal lines

21

control device

23, 24, 25

device components

26, 27, 28

Actuation

29

disconnection element

30

working line

30a, b, c

partial lines

31

Current measuring devices

32

monitoring unit

33

rectifier

34

Freewheeling diode

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 10163197 A1 [0005]
• EP 1021123 B1 [0006]
• EP 1269906 A1 [0006]

Claims (15)

Domestic appliance, in particular a dishwasher, with at least one appliance component ( 23 . 24 . 25 ), which have a working line ( 30 ) is supplied with electric power, and a monitoring unit ( 32 ), with the one by the management ( 30 ) can be detected in at least one fault case flowing fault current, characterized in that by means of the monitoring unit ( 32 ) to the device component ( 23 . 24 . 25 ) flowing current and a current flowing therefrom is detectable. Domestic appliance according to claim 1, characterized in that the difference between incoming and outgoing current for detecting the error case can be evaluated. Domestic appliance according to claim 1 or 2, characterized in that the monitoring unit ( 32 ) a first and a second current measuring device ( 31 ), the device component ( 23 . 24 . 25 ) in series in the management ( 30 ) upstream and downstream, the current measuring devices ( 31 ) in particular measuring shunts. Domestic appliance according to one of claims 1, 2 or 3, characterized in that the of the monitoring unit ( 32 ) detected differential current is comparable to a threshold value, and that in particular the size of the threshold value can be varied depending on operating conditions. Domestic appliance according to one of the preceding claims, characterized in that in the working line ( 30 ) an additional shut-off element ( 29 ) is provided, which is independent of a switching position of the drive element ( 26 . 27 . 28 ) a power supply to the device component ( 23 . 24 . 25 ) interrupts or releases. Domestic appliance according to one of the preceding claims, characterized in that the drive element ( 26 . 27 . 28 ) is a triac, a relay, a transistor or a mosfet. Domestic appliance according to one of claims 5 or 6, characterized in that the switch-off element ( 29 ) is a relay or a semiconductor. Domestic appliance according to one of the preceding claims, characterized in that the control device ( 21 ) of the household appliance with at least two or more control elements ( 26 . 27 . 28 ) of device components ( 23 . 24 . 25 ) in signal connection ( 19 ). Domestic appliance according to claim 8, characterized in that the device components ( 23 . 24 . 25 ) in sub-lines ( 30a . 30b . 30c ) of the management ( 30 ) are connected in parallel with each other. Domestic appliance according to claim 8 or 9, characterized in that the at least two device components ( 23 . 24 . 25 ) a common shutdown element ( 29 ), in particular in series with the device components connected in parallel ( 23 . 24 . 25 ) is switched. Domestic appliance according to one of claims 5 to 10, characterized in that the switch-off element ( 29 ) is permanently in its closed position during normal operation of the household appliance. Domestic appliance according to one of the preceding claims, characterized in that in the power supply of the device component ( 23 . 24 . 25 ) a pulse width modulation can be used, with which independent of network fluctuations to the device component ( 23 . 24 . 25 ) kept electrical energy remains constant. Domestic appliance according to claim 12, characterized in that in the circuit of the device component ( 23 . 24 . 25 ) a rectifier ( 33 ) is switched, which generates a DC voltage from the mains voltage. Domestic appliance according to claim 13, characterized in that the control device ( 21 ) the shutdown element ( 29 ) or the control element ( 23 . 24 . 25 ) clocked with an adjustable duty cycle, which is in particular in a range greater than 1000 Hz, in particular greater than 10 KHz. Method for operating a domestic appliance, in particular a dishwasher, with at least one appliance component ( 23 . 24 . 25 ), which have a working line ( 30 ) is supplied with electric power, and one by the working line ( 39 characterized in that a differential current measurement is carried out in which a to the device component ( 23 . 24 . 25 ) flowing current and a current flowing therefrom is detected and the difference between the inflowing and outflowing current is evaluated to detect the fault.

Images