DE102014218000A1 - Switching device for switching a power supply for an electronic control unit, household appliance and method therefor - Google Patents

Abstract

The invention relates to a switching device (52) for switching a power supply for an electronic control unit (14) of a household appliance (10), having a first connection (22) for connection to a DC voltage source (24), with a second connection (26) for connection to a power supply terminal of the control unit (14) and to a switching transistor (18) providing a switching path (16) between the first and second terminals (22, 26), the switching path (16) being connected through a third terminal (20) of the Switching transistor (18) is switchable, wherein the switching device (52) is adapted to turn on the switching path (16) by means of an on the third terminal (20) of the switching transistor (18) acting electronic switching element (28) of the switching device (52) and means a switch-off signal (30) of the control unit (14) acting on the third terminal (20) of the switching transistor (18) is switched off. According to the invention, the switching device (52) has a state unit (32) for providing a state signal (34) representing a switching state of the switching path (16) and an integrator unit (36), wherein the state unit (32) is designed to generate the state signal (34). in dependence on an actuation of the electronic switching element (28) and of the switch-off signal (30), and wherein the state unit (32) is connected to the third terminal (20) via the integrator unit (36) in order to control the switching path (16) of the switching transistor (18). in response to the state signal (34) to control.

Description

The present invention relates to a switching device for switching a power supply for an electronic control unit of a household appliance, having a first terminal for connection to a DC voltage source, a second terminal for connection to a power supply terminal of the control unit and a switching transistor having a switching path between the first and the second terminal, wherein the switching path is switchable via a third terminal of the switching transistor, wherein the switching means is adapted to switch the switching path by means of an acting on the third terminal of the switching transistor electronic switching element of the switching device and acting on the third terminal of the switching transistor Switch off the switch-off signal of the control unit. Moreover, the invention relates to a household appliance with an electrical device for providing a household appliance function, an electronic control unit for controlling the electrical device, a DC voltage source and a switching device connected to the DC voltage source and the electronic control unit for switching a power supply for the electronic control unit. Finally, the invention relates to a method for switching a power supply for an electronic control unit of a household appliance by means of a switching device, wherein the power supply is by means of a DC voltage source, wherein the power supply is switched by means of a switching path between the DC voltage source and the control unit providing switching transistor, wherein the switching path means an electronic switching element of the switching device acting on a third terminal of the switching transistor is switched on and switched off by means of a switch-off signal of the control unit acting on the third terminal of the switching transistor.

Switching devices of the generic type and corresponding methods and household appliances of the generic type are basically known, so it does not require a separate printed evidence for this. Control units are used to control in a domestic appliance electrical equipment in the intended manner, so that the household appliance can perform its intended function. Such control units are usually part of the household appliance and usually require an electrical power supply, which is usually provided by a DC voltage source, which in turn relates energy from an electrical energy storage such as an accumulator, a battery, a public power grid or the like. However, generic household appliances are often used - considered over the life - only for a fraction of the life. Therefore, it is common in generic household appliances to turn off the power supply for the control unit, so that during the period between uses of the household appliance, the energy consumption due to the control unit can be reduced.

For this purpose, it is customary in the prior art to configure the power supply for the control unit by means of a switching transistor switched off. The switching transistor is turned off by the control unit itself as soon as the control unit has finished all control functions and no further controlling functions are to be performed. To be able to put the control unit or the household appliance back into operation, an electromechanical pushbutton is connected in parallel with the switching transistor, by means of which the control unit can be supplied with electrical energy when the switching transistor is switched off, so that the control unit switches on the switching transistor again via a self-holding circuit. In this state, the control unit and thus the household appliance is then ready for use again.

The control unit is usually formed by an electronic circuit and / or a computer unit. Usually, in the power supply of these units, a capacitive support of these units supplying DC voltage is provided to ensure reliable operation of the control unit and to suppress interference. When switched off, these capacities are discharged via the control unit itself. When switched on by means of the button, these capacitances are directly connected to the DC voltage source, so that a large inrush current flows. The same occurs when, due to certain control processes, such as when restarting after power failure or the like, the switching transistor is turned on again. Again, occur during power on large current spikes that burden the switching transistor. In the prior art, therefore, both the pushbutton and the switching transistor must be designed for the correspondingly high current-carrying capacity. As a result, not only are correspondingly resilient, expensive components to be provided, but also an increased load on the DC voltage source and the capacitances provided in the control unit. In addition, such processes can adversely affect the aging of the control unit and / or the switching device.

The invention is concerned with the task of reducing the current load on the components, in particular during a switch-on process.

This object is achieved by a switching device, a household appliance and a method according to the independent claims.

A switching device according to the invention for switching a power supply for an electronic control unit of a domestic appliance comprises in particular a first terminal for connection to a DC voltage source, a second terminal for connection to a power supply terminal of the control unit and a switching transistor which provides a switching path between the first and the second terminal, wherein the switching path is switchable via a third terminal of the switching transistor, wherein the switching device is adapted to turn on the switching path by means of acting on the third terminal of the switching transistor electronic switching element of the switching device and turn off by means of acting on the third terminal of the switching transistor off signal of the control unit, wherein the switching means comprises a state unit for providing a switching state of the switching path representing Zu status signal and an integrator unit, wherein the state unit is adapted to provide the state signal in response to actuation of the electronic switching element and the switch-off signal and wherein the state unit is connected via the integrator unit to the third terminal to control the switching path of the switching transistor in response to the state signal , Unlike in the prior art, the switching transistor is no longer operated exclusively in a pure switching mode, but - as explained in more detail below - at least partially in a transition from a first switching state to a second switching state in a linear operation. This is achieved by means of the integrator unit, which outputs a change of the state signal corresponding to the third terminal of the switching transistor.

An essential idea of the invention is to be seen in that the current pulse can be reduced in particular by switching on an integration of a change of the state signal, preferably in such a way that the current pulse does not substantially or only insignificantly exceed a continuous current flow during the intended operation of the control unit , In this case, a circuit structure is selected in which the electronic switching element is no longer directly applied to the current to be switched. This ensures that both the electronic switching element and the switching transistor can be significantly relieved with respect to the current pulse load. Accordingly, the current is switched exclusively with the switching transistor. Only in this way can the effectiveness of the integrator unit occur in the manner according to the invention. For the electronic switching element, this results in a significantly reduced load, especially in the case of an electromechanical switch, a reduced contact erosion, in particular if contact bounce is to be taken into account. For the switching transistor can be achieved that the current pulse load, in particular during a switching operation such as the turn-on can be significantly reduced, so that it is possible to significantly reduce the switching transistor in terms of its design. This not only saves material costs, but it can also be advantageously used on SMD components that are suitable for high integration of electronic circuits, for example because cost-effective assembly techniques can be used. In particular, advantages with regard to integration, packing density and costs can thus be achieved.

A domestic appliance of the generic type comprises in particular a device for preparing food, for example a hob, an oven, a microwave oven, combinations thereof or the like, a device for the care of laundry items, for example treating laundry items, in particular a washing machine, a tumble dryer, an ironing device Combinations thereof or the like, a device for cleaning, in particular treating dishes, for example, a dishwasher, a vacuum cleaner or the like and also a device for the particular cooled storage of items, preferably food, for example, a refrigerator, a freezer, combinations thereof or the like , Accordingly, a household appliance function includes, for example, food preparation, laundry care, cleaning of articles, surfaces or the like, combinations thereof, or the like.

The household appliance preferably has electrical devices by means of which the intended function or use can be realized. The electrical devices may include, for example, an electric machine, an electric heater, an inverter, in particular an inverter, combinations thereof, or the like. In order to control the electrical equipment in the intended manner, the domestic appliance has the electronic control unit. This can for example have an input unit, via which a user can manually make inputs for controlling the household appliance in the desired manner. In addition, the control unit can have a display unit, by means of which operating states are recognizably displayed to the user. In addition, of course, a combination of a Display unit be provided with an input unit, for example in the form of a touch-sensitive screen or the like. Finally, the control unit may also include sensors and their evaluation to control the electrical device according to a control program. Furthermore, the control unit can also be program-based and, in particular, have a computer unit for this purpose, so that different operating sequences can be selected and / or realized in a simple manner, for example by a user input and / or depending on acquired measured values by means of the sensors. Finally, the control unit can also be used for communication with appliances external to household appliances, for example by establishing a communication connection to a communication terminal, in particular a mobile radio terminal. The communication connection can be made for example via a communication network such as the Internet, a mobile radio network, combinations thereof or the like.

A generic household appliance is used by the user usually only during a relatively short period of use, which is much shorter than the life of the household appliance. During the rest of the period between periods of use, the household appliance is not in normal operation. Mostly it is switched off. During the period of use, it is therefore not necessary to provide the control unit with electrical energy. In such household appliances, therefore, a shutdown of the power supply of the control unit is provided so that the consumption of electrical energy between the periods of use can be reduced. The control unit of the household appliance normally requires only a fraction of the total power consumed by the household appliance during normal operation of the household appliance during a period of use for its intended operation. Accordingly, the DC voltage source is adapted so that it can reliably supply the control unit with electrical energy during normal operation, but at the same time it is limited in terms of power available, so that the required power to be provided can be provided inexpensively and by a compact DC voltage source.

The DC voltage source can be, for example, an electrical energy store such as an accumulator, a battery, combinations thereof or the like. It can also be formed by a power supply, which derives its energy from, for example, a public power grid. Again, combinations may be provided. In particular, the DC voltage source provides a smoothed DC voltage, so that the control unit, in particular, if it has electronic components, a computer unit, combinations thereof or the like, can ensure the reliable operation of the control unit as intended.

The switching transistor may for example be a bipolar transistor, but also a field effect transistor, in particular a metal oxide semiconductor field effect transistor (MOSFET), an isolated gate bipolar transistor (IGBT), or the like. In principle, the switching transistor may also be formed by a thyristor arrangement, in particular by a gate turn-off thyristor (GTO) or the like. Of course, the switching transistor may also be formed by combination circuits using the aforementioned components. The switching transistor is arranged such that its switching path is connected between the first and the second terminal. The switching transistor has a third terminal as a control terminal, which can be acted upon by a switching signal to switch the switching path between the first and the second terminal in the desired switching state, in particular the switched on and the off state. Depending on the switching signal, the respective switching state of the switching path is established. For this purpose, the switching signal is preferably formed as a digital signal, wherein a first level of the switching signal is selected such that the switching path assumes the on state, whereas a second level is selected such that the switching path occupies the off state.

The switching transistor is only operated at most partially in a switching operation. Switching operation means that a very low electrical resistance is provided in an activated state between the two connections forming the switching path of the switching transistor, so that a high current flow is possible at very low residual voltage. When switched off, the switching path of the switching transistor is high impedance, that is, it provides a high electrical resistance, so that there is substantially no or only a very low, in particular negligible current flow even at high voltage applied to the switching path. A transition from one state to the other takes place in the prior art with a shortest possible transition time, also called switching time, which is usually determined essentially by physical properties of the switching transistor. This differs from a linear operation, which is not used in the prior art but in switching transistors in switching operation.

In contrast to this, however, the invention provides that the switching transistor is operated in a linear mode at least during a state change in the form of a transition from the switched-off state to the switched-on state (switch-on process). In a reverse state change (switch-off), the switching operation is preferably - as previously explained - realized. Alternatively, however, a linear operation can also be provided here. The linear operation preferably extends in a period between the two states "on" and "off".

The electronic switching element may be formed by a semiconductor switch, in particular a manually controllable by a control switching transistor, an electromechanical switch, combinations thereof or the like, The electromechanical switch may be formed for example as a manually operable device, which is arranged for example on a control panel of the household appliance , Preferably, the electronic switching element is part of the switching device, but it may also be separate from the switching device and be connected only to this. The electromechanical probe preferably has a metallic switching contact, which is closed in a pressure actuation due to a manual action, so that between two terminals of the probe, a low-resistance or good electrically conductive connection is made. As soon as the manual action on the button is eliminated, the electrically conductive connection is interrupted, as a rule due to a spring preload. The electronic switching element is used to enable or start activation of the power supply of the control unit by the switching unit in the off state of the switching path of the switching transistor. In the prior art is provided at this point that the electromechanical switch is connected in parallel to the switching path of the switching transistor, so that the switching path of the switching transistor is short-circuited by pressing the button. As a result, the control unit is briefly supplied via the button with electrical energy from the DC voltage source, so that the control unit immediately delivers a hold signal to the switching transistor, which then turns on its switching path, so that when the manual operation on the button, the energy supply via the switching transistor is maintained.

As soon as the control unit has finished all control operations and no further control tasks are pending, the control unit outputs a switch-off signal which causes the switching transistor to set the switching path to the switched-off state. Thereupon, the electrical voltage available at the control unit builds up over the power consumption of the control unit until the voltage has substantially subsided. The control unit is in this state substantially voltage or de-energized. Thereby, a consumption of electrical energy between the periods of use of the household appliance, in particular in stand-by mode, can be reduced.

In order to reduce the load on the electronic switching element and the switching transistor, the invention provides the state unit, which may be formed by an electronic memory cell. The state unit provides a state signal representing a switching state of the switching path. Preferably, the state signal is a digital signal, so that it has, for example, two signal levels, namely a signal level representing an on state of the switching path, whereas a second signal level represents an off state of the switching path. The electronic switching element is - in contrast to the prior art - no longer connected in parallel to the switching transistor, but according to the invention to the state unit. As a result, the electronic switching element upon actuation is basically no longer acted upon by an inrush current, but only with a small control current that is required to activate or actuate the state unit. The electronic switching element can be designed to be correspondingly smaller and at the same time achieve higher reliability and service life.

The control unit is preferably also connected to the control unit in such a way that the switch-off signal of the control unit is transmitted to the status unit. This makes it possible to operate the state unit by means of the control unit. Neither the electronic switching element nor the control unit itself thus act directly controlling the switching transistor. With regard to the signal flow, the state unit is now interposed according to the invention. Thereby, the state unit can provide the status signal in response to an operation of the electronic switching element and the turn-off signal.

So that now but not the full load of the electronic switching element is transmitted to the switching transistor, the invention provides that the state signal from the state unit is not performed directly on the third terminal of the switching transistor, but instead the state unit via the integrator at the third terminal of the switching transistor is connected to the switching path of the switching transistor in Control dependence of the state signal. By the integrator unit can be achieved that a switching edge of the state signal is extended, so that the switching transistor does not switch with its minimum possible switching speed, the switching path, but with a prolonged by a design of the integrator switching time. This is preferably the switch-on time, so that as a result current pulses when switching on can be considerably reduced, if not completely suppressed. Basically, the integrator unit may provide a corresponding delay for powering off as well. This may be advantageous, for example, if inductances are present in the circuit whose rapid switching off could lead to short-term voltage peaks and dangerous states. Again, the invention can thus bring about an improvement.

However, it proves to be particularly advantageous when the integrator unit is designed to enable a switch-off operation of the switching transistor shorter in time than a switch-on process. As a result, on the one hand the advantage of the time-prolonged switching on with reduction of the current pulse can be achieved and at the same time a fast switching off can be realized, so that a reliable shutdown can be realized, in particular in case of faults or the like. For example, it may be provided that the integrator unit for a rising switching edge of the state signal and for a falling edge of the state signal has different circuit branches, which are selectively effective, for example. This can be achieved, for example, with the aid of additional diodes in the integrator unit.

Preferably, the state unit is a bistable flip-flop circuit having a first and a second input terminal, wherein the state unit is formed, at a first control signal at the first terminal a state signal representing an on state and at a second control signal at the second input terminal a off State signal representing state. This makes it possible to achieve a corresponding condition signal provision via separate inputs of the state unit. Especially with multiple operations reliable functions can be achieved here. The flip-flop circuit can be realized, for example, with discrete components. In addition, it can also be realized by an integrated circuit, in which at least one corresponding circuit is already realized. Regarding the function, the flip-flop circuit may be formed as a D flip-flop, an RS flip-flop, a JK flip-flop or the like.

Preferably, the control unit for providing the switch-off signal is connected via a first amplifier circuit to the second input terminal of the flip-flop circuit. As a result, the switch-off signal of the control unit can act directly on the state unit, in this case the flip-flop circuit, and cause a state change of the state signal to a state signal representing the switched-off state.

The electronic switching element is advantageously connected to the first input terminal of the flip-flop circuit, so that a state signal representing the switched-on state can be effected by a manual actuation of the electronic switching element.

In particular, it is proposed that the electronic switching element is connected via an interference suppression circuit to the first input terminal of the flip-flop circuit. By providing a suppression circuit, a reliable control of the state unit can be achieved. For example, due to interference caused by the noise suppression circuit can be reduced or suppressed. The reliability of the switching device according to the invention can be further improved.

According to a development, the interference suppression circuit has a low-pass filter or a bandpass filter. These filter types are particularly well suited for the realization of interference suppression and can also be implemented cost-effectively. Depending on the characteristics of the electronic switching element and / or the interference signal to be suppressed, either the low-pass filter or the band-pass filter can be selected. The interference signal can also be generated, for example, by an undesired, for example brief, operation.

Advantageously, the switching device has a voltage interrupt protection unit, which is connected to the first input terminal of the flip-flop circuit. The voltage interrupt protection unit serves to ensure, for example, short-term, power interruptions of the DC voltage source, an automatic restart of the switching transistor, so that the already begun period of use of the household appliance can be continued in the intended manner. For this purpose, the voltage interrupt protection unit can have an energy store, in particular a capacitor, which can be charged over a predetermined time constant. The capacitor can be charged via a resistor for this purpose. By means of an adjusting the capacitor voltage, a control signal can be provided, which is a switching element such as a Transistor, in particular MOSFET switches, which in turn sets the state unit. For example, it can be provided that a power interruption of a few seconds to a minute or several minutes or even a larger period can be bridged. It is therefore no longer necessary in the event of a power interruption that the user manually re-activates the household appliance and reprograms and starts the already started utilization program. With the voltage interruption protection unit, it can be achieved, in particular, that an already executed usage program can be automatically continued after a voltage return.

In particular, the voltage interrupt protection unit is designed to be deactivated by means of the switch-off signal. With this function can be achieved that a reliable shutdown can be realized, even if the off signal is only pending. Overall, the reliability of the function can be improved.

Preferably, the switching device has a second amplifier circuit, via which the state unit is connected to the integrator unit. With the second amplifier circuit, a gain of the state signal and a level adjustment can be achieved so that the switching level switching switching level can be reliably achieved. In addition, with the second amplifier circuit signal matching can be achieved to further improve the reliability of the switching device of the invention.

Particularly advantageously, the switching transistor is a MOSFET whose source terminal forms the first terminal and whose drain terminal forms the second terminal, and the integrator unit provides a resistance circuit for connection to a gate terminal of the MOSFET forming the third terminal. Due to its properties, the MOSFET is particularly suitable as a switching transistor for the switching device according to the invention. With little circuit complexity, therefore, the function of the invention can be achieved. It proves particularly advantageous if a gate-source capacitance cooperates with the integrator unit and thus improves the desired switch-on time.

In particular, the resistance circuit is designed to form a time constant which is greater for the switch-on of the switching path of the switching transistor than for the switch-off. For this purpose, different circuit branches may be provided, which preferably react to the respective switching edges of the state signal.

Advantageously, the integrator unit has an electrical capacitance connected in parallel with the gate-drain path of the MOSFET. As a result, the function of the integrator unit can be further improved, in particular with regard to the adjustability of the switching speed of the switching transistor.

Furthermore, the switching device preferably has a priority circuit, which is designed to suppress the switch-off signal when the electronic switching element and the switch-off signal of the control unit collapse in time. This function takes into account that a manual operation of the electronic switching element, a turning on of the household appliance by the user is desired. As a result, the operation by the user takes precedence over an operation, here the shutdown of the control unit. The ease of use can be improved in this way.

Advantageous embodiments of the switching device according to the invention are to be regarded as advantageous embodiments of the method. For this purpose, representational components of the switching device are formed alone or in combination to allow the method steps.

Further features of the invention will become apparent from the claims, the figures and the description of the figures. All the features and feature combinations mentioned above in the description and the features and feature combinations mentioned below in the description of the figures and / or shown alone in the figures can be used not only in the respectively indicated combination but also in other combinations or alone, without the frame to leave the invention. Thus, embodiments of the invention are to be regarded as encompassed and disclosed, which are not explicitly shown and explained in the figures, however, emerge and can be produced by separated combinations of features from the embodiments explained.

Embodiments of the invention are explained in more detail below with reference to schematic drawings. In the figures, like reference characters designate like functions and features.

Show it:

1 in a schematically opened front view of a washing machine as a household appliance with a switching device according to the invention,

2 a schematic diagram of a switching device for the washing machine according to 1 according to the prior art, and

3 in a schematic circuit diagram view of a switching device for the washing machine according to 1 according to the invention.

1 shows a washing machine 10 as a household appliance in a diagrammatically opened front view. In the 1 illustrated washing machine 10 further comprises a rotatably mounted washing drum 54 on that over a drive belt 58 by means of a drive motor 56 is drivable. The drive motor 56 is over a line 70 to a switching unit 52 connected, which in turn is connected in unspecified manner to an electrical power grid, here the public power grid. To operate the washing machine 10 the public power grid provides the required electrical energy. Not shown that in this case the drive motor 56 comprises a converter by means of which speeds and torques can be set in the desired manner.

To the switching unit 52 is also a DC voltage source 24 connected, which is presently designed as a power supply and which is connected directly to the public power grid, so that they preferably permanently provides a DC electrical voltage. The DC electrical voltage is smoothed here, so they directly to the electrical power supply of a control unit 14 of the washing machine 10 can be used. To the DC voltage source 24 is a switching device 12 . 52 connected to the DC power source 24 provided smoothed DC voltage switching for the control unit 14 provides. In this way, the control unit 14 with electrical energy via the switching device 12 . 52 provided.

The control unit 14 has an unspecified input and output unit, which is presently provided as a touch-sensitive screen and provides a user interface for a user. The control unit 14 further comprises a computer unit μP, so that the control unit 14 in the desired manner can perform washing programs to with the washing machine 10 To subject laundry items in the desired manner to a cleaning treatment.

The computer unit μP is via a line 72 to the drive motor 56 connected so that the drive motor 56 can be driven in the intended manner. Not shown are other peripherals of the washing machine 10 For example, controls for the water supply and / or water discharge, a liquor circulation, a heater and the like, which are preferably also controlled by the computer unit .mu.P.

During normal operation, that is, during a period of use for performing a washing operation, all the units are the washing machine 10 supplied with electrical energy. When the washing process is finished, the control unit delivers 14 a switch-off signal, by means of which the switching device 12 . 52 is turned off. This will be the power supply for the control unit 14 disabled, so the control unit 14 is energized or de-energized.

2 shows a schematic diagram view of a circuit diagram for a switching device 12 according to the prior art. The switching device 12 has a first connection 22 for connection to the DC voltage source 24 , a second connection 26 for connection to a power supply terminal of the control unit 14 and a switching transistor 18 on, the one switching path 16 between the first and the second connection 22 . 26 provides. The switching path 16 is via a third port 20 of the switching transistor 18 switchable. The switching transistor 18 is designed in the present case as a MOSFET. The switching device 12 has a button 28 as an electronic switching element, which is designed as a manually operable electromechanical probe and also at the first and the second terminal 22 . 26 , parallel to the switching transistor 18 , connected. Out 1 can be seen that at the connection 26 connected control unit 14 unspecified electrical capacitances, here capacitors. The operation of the switch 28 therefore leads to a pulsed current load both the DC voltage source 24 as well as the button 26 and the control unit 14 , This is the button 28 exposed to increased stress, so that its switching contact must be designed for a correspondingly high stress.

It can be seen, moreover, that the switching on of the switching transistor 18 is also instantaneous, that is, the switching transistor 18 switches on with its design-related switch-on time. For MOSFETs, this turn-on time is very short, so when the switching transistor is turned on 18 a very large current pulse through the switching transistor 18 must be guided through. Again, the DC source 24 as well as the control unit 14 accordingly charged with the current pulse. Other driver components 66 that represent a driver circuit are at the third port 20 of the switching transistor 18 connected to its switching path with a switch-off 30 to be able to act on. The driver components 66 include below another two bipolar transistors, which are interconnected in a known manner to the third terminal 20 with the switch-off signal 30 to be able to act on. This circuit does not provide a state unit with a status signal. This circuit known in the prior art is familiar to the person skilled in the art, so that no further discussion is required.

3 shows a schematic diagram of a switching device 52 according to the invention, the first connection 22 for connection to the DC voltage source 24 , a second connection 26 for connection to a power supply terminal of the control unit 14 and a switching transistor 18 having a switching path 16 between the first and the second connection 22 . 26 provides. The switching path 16 is via a third port 20 of the switching transistor 18 switchable.

The switching device 52 is designed to the switching path 16 by means of one on the third connection 20 of the switching transistor 18 acting electromechanical buttons of the switching device 52 turn on and on to the third port 20 of the switching transistor 18 to turn off acting control signal of the control unit.

For this purpose, the switching device 52 According to the invention, a state unit 32 in the form of a flip-flop circuit, here a bistable flip-flop 40 , on. The state unit 32 represents a switching state of the switching path 16 representing status signal 34 ready.

Furthermore, the switching device comprises 52 an integrator unit 36 that is a resistance circuit 62 includes. The resistance circuit 62 comprises two resistors connected in series, the series circuit being connected at one end to a capacitor providing an electrical capacitance, which is connected in parallel with the drain-gate path of the switching transistor 18 connected. A non-designated Zener diode, which is parallel to the gate-source path of the switching transistor 18 is connected, serves in a known manner to a gate circuit.

The integrator unit 36 is at a center tap of the series connection of the resistance circuit 62 by a second amplifier circuit 60 applied. The second amplifier circuit 60 has a two-stage transistor amplifier in which bipolar transistors are provided in emitter circuit.

The second amplifier circuit 60 is between the state unit 32 and the integrator unit 36 interposed. The second amplifier circuit 60 is thus at its input with the status signal 34 the state unit 32 applied.

The integrator unit 36 allows due to their circuit, switching edges of the state signal 34 to stretch in time, so that the turn-on or the turn-off of the switching transistor 18 can be extended. As a result, current pulses, in particular during switching on the switching path, can be reduced or even avoided.

The state unit 32 shows the formed by discrete components bistable flip-flop circuit 40 with a first and a second input terminal 42 . 44 on. The state unit 32 is formed at a first control signal at the first input terminal 42 a status signal representing an on-state, and a second control signal at the second input terminal 44 to provide a status signal representing an off state.

In the present embodiment it is provided that the control unit 14 for providing the switch-off signal 30 via a first amplifier circuit 38 at the second input terminal 44 the flip-flop circuit 40 connected. The first amplifier circuit 38 causes a signal adaptation or amplification of the switch-off signal 30 so that it conforms to the signal requirements of the state unit 32 is adapted and reliably providing the state signal representing the turned-off state 34 to enable.

The button 28 is via a suppression circuit 46 at the first input connection 42 the flip-flop circuit 40 connected. The suppression circuit 46 includes a low-pass filter for this purpose.

In addition, the switching device 52 a voltage interruption protection unit 50 on, which also at the first input connection 42 the flip-flop circuit 40 connected. It is thus parallel to the button 28 at the first input connection 42 connected. By means of the voltage interrupt protection unit 50 can be achieved that at power interruptions of the DC voltage source 24 a reliable restart can be ensured after voltage return, so that the intended operation of the washing machine 10 can be continued without a user needing to intervene. For this purpose, the voltage interrupt protection unit 50 an unsigned capacitor as an energy storage, which ensures such that when power returns a signal at the first input terminal 42 the state unit 32 is applied, so from the state unit 32 a state signal representing the on-state 34 provided.

With the invention, it is also possible to ensure that the switching transistor is switched off after a power failure, for example a brief one 18 is not subjected to a large inrush current.

The above-described embodiments are merely illustrative of the invention and are not limitative of it. Thus, of course, functions, in particular electronic components and the switching device, be designed arbitrarily, without departing from the spirit of the invention.

The advantages and features and embodiments described for the method according to the invention apply equally to the switching device according to the invention and vice versa. Consequently, device features corresponding to device features and vice versa may be provided.

LIST OF REFERENCE NUMBERS

10

 Washing machine

12

 switching device

14

 control unit

16

 contact gap

18

 MOSFET

20

 Gate terminal

22

 first connection

24

 DC voltage source

26

 second connection

28

 button

30

 switch-off

32

 state unit

34

 state signal

36

 integrator unit

38

 first amplifier circuit

40

 bistable flop-flop

42

 first input connection

44

 second input connection

46

 snubber

48

 Low Pass Filter

50

 Power interruption protection unit

52

 switching unit

54

 washing drum

56

 drive motor

58

 belts

60

 second amplifier circuit

62

 resistor circuit

64

 capacitor

70

 management

72

 management

Claims (15)

Switching device ( 52 ) for switching a power supply for an electronic control unit ( 14 ) of a household appliance ( 10 ), with a first connection ( 22 ) for connection to a DC voltage source ( 24 ), with a second connection ( 26 ) for connection to a power supply terminal of the control unit ( 14 ) and with a switching transistor ( 18 ), which has a switching path ( 16 ) between the first and second terminals ( 22 . 26 ), wherein the switching path ( 16 ) via a third port ( 20 ) of the switching transistor ( 18 ) is switchable, wherein the switching device ( 52 ) is adapted to the switching path ( 16 ) by means of a third connection ( 20 ) of the switching transistor ( 18 ) acting electronic switching element ( 28 ) of the switching device ( 52 ) and connect it to the third port ( 20 ) of the switching transistor ( 18 ) acting off signal ( 30 ) of the control unit ( 14 ), characterized by a state unit ( 32 ) for providing a switching state of the switching path ( 16 ) representing state signal ( 34 ) and an integrator unit ( 36 ), wherein the state unit ( 32 ) is adapted to the status signal ( 34 ) in response to an actuation of the electronic switching element ( 28 ) and the switch-off signal ( 30 ) and wherein the state unit ( 32 ) via the integrator unit ( 36 ) at the third port ( 20 ) is connected to the switching path ( 16 ) of the switching transistor ( 18 ) as a function of the status signal ( 34 ) to control. Switching device according to claim 1, characterized in that the integrator unit ( 36 ) is formed, a turn-off of the switching transistor ( 18 ) time shorter than a switch-on to allow. Switching device according to claim 1 or 2, characterized in that the state unit ( 32 ) a bistable flip-flop circuit ( 40 ) with a first and a second input terminal ( 42 . 44 ), wherein the state unit ( 32 ) is formed at a first control signal at the first input terminal ( 42 ) a state signal representing an on-state, and a second control signal at the second input terminal (FIG. 44 ) to provide a state signal representing an off state. Switching device according to claim 3, characterized in that the control unit ( 14 ) for providing the switch-off signal ( 30 ) via a first amplifier circuit ( 38 ) at the second input terminal ( 44 ) of the flip-flop circuit ( 40 ) connected. Switching device according to claim 3 or 4, characterized in that the electronic switching element ( 28 ) via an interference suppression circuit ( 46 ) at the first input terminal ( 42 ) of the flip-flop circuit ( 40 ) connected. Switching device according to claim 5, characterized in that the suppression circuit ( 46 ) a low-pass filter ( 48 ) or a bandpass filter. Switching device according to one of Claims 3 to 6, characterized by a voltage interruption protection unit ( 50 ) located at the first input terminal ( 42 ) of the flip-flop circuit ( 40 ) connected. Switching device according to claim 7, characterized in that the voltage interruption protection unit ( 50 ) is designed, by means of the switch-off signal ( 30 ) to be deactivated. Switching device according to one of the preceding claims, characterized by a second amplifier circuit ( 60 ) via which the state unit ( 32 ) to the integrator unit ( 36 ) connected. Switching device according to one of the preceding claims, characterized in that the switching transistor is a MOSFET ( 18 ) whose source terminal is the first terminal ( 22 ) and its drain connection the second connection ( 26 ) and the integrator unit ( 36 ) a resistance circuit ( 62 ) for connection to a third port ( 20 ) forming the gate terminal of the MOSFET ( 18 ). Switching device according to claim 10, characterized in that the resistance circuit ( 62 ) is designed to form a time constant which is required for the switch-on operation of the switching path ( 16 ) of the switching transistor ( 18 ) is greater than for the switch-off. Switching device according to claim 10 or 11, characterized in that the integrator unit ( 36 ) one to a gate-drain path of the MOSFET ( 18 ) parallel electrical capacity ( 64 ) having. Switching device according to one of claims 1 to 9, characterized by a priority circuit, which is adapted to a temporal coincidence of the actuation of the electronic switching element ( 28 ) and the switch-off signal ( 30 ) of the control unit ( 14 ), the switch-off signal ( 30 ) to suppress. Household appliance ( 10 ) with an electrical device ( 56 ) for providing a household application function, an electronic control unit ( 14 ) for controlling the electrical device ( 56 ), a DC voltage source ( 24 ) and one to the DC voltage source ( 24 ) and the electronic control unit ( 14 ) connected switching device ( 52 ) for switching a power supply for the electronic control unit ( 14 ) according to any one of the preceding claims. Method for switching a power supply for an electronic control unit ( 14 ) of a household appliance ( 10 ) by means of a switching device ( 52 ), wherein the power supply by means of a DC voltage source ( 24 ), wherein the energy supply by means of a switching path ( 16 ) between the DC voltage source ( 24 ) and the control unit ( 14 ) providing switching transistor ( 18 ), wherein the switching path ( 16 ) by means of a third connection ( 20 ) of the switching transistor ( 18 ) acting electronic switching element ( 28 ) of the switching device ( 52 ) and connected to the third port ( 20 ) of the switching transistor ( 18 ) acting off signal ( 30 ) of the control unit ( 14 ) is switched off, characterized in that by means of a state unit ( 32 ) a switching state of the switching path ( 16 ) representing state signal ( 34 ) in response to an actuation of the electronic switching element ( 28 ) and the switch-off signal ( 30 ) via an integrator unit ( 36 ) at the third port ( 20 ) is provided to the switching path ( 16 ) of the switching transistor ( 18 ) as a function of the status signal ( 34 ) to control.

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