CN109415866B - Dynamic control of door opener of household appliance, especially with DC supply voltage - Google Patents

Abstract

The invention relates to a method for actuating a door opener (10) of a household appliance (1) comprising an electromechanical actuator (11) during an opening process, the household appliance comprising a door (2), wherein the actuator (11) comprises two actuator contacts (14, 15) for an electrical actuation, by: providing a supply voltage (18) between an electrical supply connection (16) and an electrical reference connection (17) of the door opener (10), said supply voltage having a predetermined voltage profile in a specific operating state of the domestic appliance (1); -providing electrical coupling means (13) for coupling a first of the two actuator connections (14, 15) to the supply connection (16) and/or a second of the two actuator connections (14, 15) to the reference connection (17) as required; coupling a supply voltage (18) to the two actuator connections (14, 15) by means of a coupling device (13) as a function of a pulsed coupling signal (19) for the electrical actuation of the actuator (11); generating a pressure-opening force for acting on the door (2) as a function of an electrical actuation of the actuator (11); and generating a pulsed coupling signal (19) as a function of a predefined voltage profile and/or as a function of a provided coupling device (13) in order to achieve a temporal change in the pressing-off force, said temporal change having a rising envelope curve.

Description

Dynamic control of door opener of household appliance, especially with DC supply voltage

Technical Field

The invention relates to a method for actuating a door opener of a household appliance and to a door opener in a household appliance. The invention also relates to a household appliance having such a door opening device.

Background

Household appliances for the care of laundry, which have an interior space that can be closed by means of a door, such as washing machines, laundry dryers or laundry dryer combinations, usually have a closure device which holds the door in a closed position by means of a force closure. Modern household appliances can be equipped with electromechanical door openers for applying a press-open force to the inside of the household appliance door in order to overcome the locking by the force applied by the closure device. A household appliance with such a door opening device is known from DE 102013223431B 3 and from DE 102014201924 a 1.

However, such automatic opening processes must meet predefined requirements for safety and comfort of the opening process.

Disclosure of Invention

It is therefore an object of the present invention to provide a method, a door opener and a household appliance which provide increased safety and improved comfort during opening of the door.

The invention proceeds from a method for actuating a door opener of a household appliance comprising a door during an opening process, the door opener comprising an electromechanical actuator, wherein the actuator comprises two actuator contacts for an electrical actuation. The method comprises the following steps: providing a supply voltage between an electrical supply connection and an electrical reference connection of the door opener, said supply voltage having a voltage form which is predefined in a specific operating state of the domestic appliance; electrical coupling means are provided for coupling a first of the two actuator connections to the supply connection and/or a second of the two actuator connections to the reference connection, as required. Further, the method comprises: coupling a supply voltage to the two actuator connections by means of a coupling device as a function of the pulsed coupling signal for electrically actuating the actuator; and to generate a pressure opening force for acting on the door according to the electric actuation of the actuator. An electromechanical actuator can relate to an actuator having an electromagnetic coil, preferably a cylinder coil, connected between two actuator connections, which electromagnetic coil can be actuated in such a way that a magnetic force can be exerted on a movable actuator element. The movable actuator element is preferably a magnetizable material, in particular a ferromagnetic material. The movable actuator element can be arranged such that it is at least partially supported outside the inner region of the magnet coil in the rest position and is pulled in the direction of the magnet coil when the actuator is actuated electrically.

In the case of using magnetizable materials as movable actuator elements, the attraction force is based on a reluctance force, which is based on a change in electromagnetic resistance. Here, the force generated is proportional to the square of the current flowing through the electromagnetic coil, which generates the magnetic field. The force effect on the movable actuator element is therefore independent of the sign of the current through the electromagnetic coil, which enables such embodiments of electromechanical actuators to be used also for direct actuation with an alternating signal (AC). Alternatively, it is possible to provide for the movable actuator element to use a permanently magnetic material, which requires additional rectification in order to electrically actuate the electromagnetic coil when a supply voltage in the form of an AC voltage is used.

According to the invention, the method is extended by: the pulsed coupling signal is generated as a function of a predefined voltage profile and/or as a function of a provided coupling device for the purpose of generating a temporal change in the pressing-off force, said temporal change having a rising envelope curve. Here, an envelope curve is understood to mean the following curve line: the curve line accordingly encounters a time-varying profile of the push-open force in the vicinity of a local minimum. In the simplest case, the envelope curve is a sequence of straight line segments. In a simplified manner, the envelope curve can also be determined in the following manner: the corresponding local maxima are connected by straight line segments. In this case it happens that: the envelope curve is not in contact with the temporally changing profile of the push-off force in the vicinity of the local maximum, but intersects it, wherein the deviation from the "ideal envelope curve" is negligibly small. The envelope curve can therefore be described in a simplified manner by an interpolated (in particular linearly interpolated) profile of the time-dependent profile of the pressure-release force with a local maximum of positive sign.

The invention is based on the following recognition: due to the alternating voltage-based actuation, which is usually used for applications in such door openers, which enables a very simple implementation of a actuated switching circuit on the basis of a Triac or a relay, there is a limit in the time-adjustable characteristic of the opening force.

Current implementations of door openers use additional pins to press/pop the door from its closed position. The pin is guided by operating a solenoid. In this case, the pin and the solenoid require a defined force in order to overcome the holding force of the door closer. When using AC maneuvers for the electromagnetic coil, the energy required to open the door must still be provided within a half cycle (10 milliseconds in the case of 50 hz). This means that sufficient energy must be provided in about 10 milliseconds. Then, the energy in the electromagnetic coil does not increase further.

This short time results in some disadvantages. The duration of the operation of the shock has a greater dependence on the frequency. In the case of a longer operating period, during which the solenoid is activated, this can be due to zero crossing

And vibration occurs, and at the zero crossing, the current through the solenoid becomes zero. The door, the household appliance and the door holding mechanism are mechanical parts assembled together. The following can therefore occur: they absorb the effect of the rapid impact of the door opener in such a way that they form a mechanical filter for impacts lasting a maximum of 10 milliseconds. Furthermore, large current pulses for actuating the actuator are required. In addition, voltage fluctuations can result in different impact forces, based on different energies provided to the electromagnetic coil within 10 milliseconds. Therefore, the pair of 170 volts and 2 cannot be realizedFine tuning of voltages between 60 volts. In order to ensure that the door is opened in any case, also in the case of small voltages of 170 volts AC high, an excessively large impact at 260 volts AC is correspondingly to be expected.

By actuating the actuator such that the temporal change in the pressing-open force has a rising envelope curve, a higher safety and an improved comfort of the door opener can be achieved. In particular, the door can thereby be prevented from violently hitting the user and injuring him.

According to an advantageous embodiment of the method, the provision of the coupling device and the generation of the pulsed coupling signal are implemented as: during the active pulse phase of the coupling signal, the temporal change in the pressing-off force has a sequence of at least two local maxima, which lie on or in the vicinity of the rising envelope curve, wherein a second local maximum of the at least two local maxima, which immediately follows in time a first local maximum of the at least two local maxima, has a greater value than the first local maximum. In this way the maximum force applied to the door can be gradually increased. Particularly preferably, the provision of the coupling device and the generation of the pulsed coupling signal are implemented as: such that the sequence of at least two local maxima has a third local maximum immediately after the second local maximum in time, which has a greater value than the second local maximum. This enables a further, well-graduated application of the opening force to the door.

According to an advantageous embodiment of the method, the supply voltage is provided by a direct current source. This results in greater flexibility in the manner in which the electromechanical actuator is actuated, in particular the elimination of the effect due to the zero crossing which occurs as a function of the principle when an alternating voltage is used.

Alternatively, provision can be made for the supply voltage to be provided by an ac power supply. Preferably, in this case, the rectifier is connected between the supply voltage and the electromechanical actuator. The use of a rectifier, which is supplied by an ac power source, therefore also makes it possible to use permanently magnetic materials as movable actuator elements. Furthermore, an electrical filter element can be provided behind the rectifier, i.e. on the rectifying side (to which the actuator is connected), which filter element makes it possible to reduce disturbances in the temporal course of the opening force due to the zero crossing of the alternating voltage.

According to a further advantageous embodiment of the method, the coupling signal during the opening process is generated in a sequence of a plurality of single pulses spaced apart in time from one another. The variation of the pressing-open force, which has a rising envelope curve, can thus be optimized according to the requirements with regard to a safe and comfortable opening process of the door.

Alternatively, the coupling signal during the opening process can be generated in a single pulse. The shape of the temporal profile of the opening force and the shape of the rising envelope curve is determined here by the electrical coupling element itself. The desired temporal variation of the pressing-off force can thus be achieved by selecting a correspondingly suitable electrical coupling element provided by the method according to the invention.

According to a further advantageous embodiment of the method, the coupling signal is generated as a function of a first signal which indicates the open state of the door and/or as a function of a second signal which indicates the locked state of the door. Thereby, the door opening device can softly open the door and at the same time check whether the door has been opened. In the case of an already opened door, the door opener interrupts the actuation of the door in order to avoid additional impacts on the door, which could hit a user of the household appliance. Furthermore, the household appliance can be equipped with a door closing system which also provides for the locking of the door, which is of importance in particular in washing machines in the form of front-end loaders with a loading opening arranged on the front side. Here, if the door is opened when a critical water level is exceeded in the drum, a flood may be caused. In the case of a door lock, the door opening mechanism is also expediently locked in order to prevent damage to the household appliance, in particular to the locking device or parts of the door opening device.

The invention further relates to a door opener in a domestic appliance comprising a door, wherein the door opener comprises an electrical supply connection and an electrical reference connection, between which a supply voltage can be provided, which has a predetermined voltage pattern in a specific operating state of the domestic appliance. The door opener furthermore comprises an electromechanical actuator for generating a pressing-open force for acting on the door as a function of an electrical actuation of the actuator, which actuator comprises two actuator contacts for the electrical actuation, and the door opener comprises an electrical coupling device which is designed to couple a first of the two actuator contacts to the supply contact and/or a second of the two actuator contacts to the reference contact in order to actuate the actuator electrically as a function of a pulsed coupling signal. The pulsed coupled signal is in particular a binary signal capable of having two states, coupled (on) and uncoupled (off).

According to an advantageous embodiment of the door opener, the electrical coupling device has a resistance element which is electrically connected in series to the actuator and has a variable resistance. The variable resistor is in particular a temperature-dependent resistor, preferably a thermistor (NTC), the resistance value of which has a negative temperature coefficient. Such a resistance element can be used not only as a supply voltage in the form of a direct voltage but also as an alternating voltage. Starting from a rest state of the door opener in which the resistance element is at the ambient temperature and has a high resistance value, the current flowing through the resistance element causes a self-heating of the resistance element and thus a reduction of the resistance value. This leads to an increase in the current through the actuator, for example through the solenoid coil of the actuator, which is connected between the two actuator connections, wherein, in the case of operation with alternating voltage as supply voltage, this should be correctly referred to as an increase in the current amplitude rather than an increase in the current, in order to avoid misinterpretations in the drop in the current value determined by the shape of the voltage curve. The temporal variation of the pressing-off force, which has a rising envelope curve as soon as the coupling signal switches the electric coupling device into the coupling state (on), can thus be achieved by a suitable selection of the resistor element with parameters adapted to the actuator solenoid, taking into account the operating voltage set to the supply voltage.

According to a further advantageous embodiment of the door opener, the electric coupling device has a first electronic switching element which is connected electrically in series to the actuator. In the case of a direct voltage (DC) as supply voltage, the electronic switching element is preferably designed as a transistor, in particular as a bipolar transistor or a field effect transistor, particularly preferably as a field effect transistor with an insulated gate (MOSFET or IGFET). In the case of an alternating voltage (AC) as supply voltage, the first electronic switching element is preferably designed as a Triac or as a relay, in particular as a semiconductor relay. In this case, it is preferably possible to perform an electrical isolation operation by means of an optical connection, for example by means of an optical waveguide.

According to an advantageous embodiment of the door opener, the electrical coupling device has a second electronic switching element, which is electrically connected in series to the first electronic switching element. Thus, the actuator, which can be represented by an electromagnetic coil connected between two actuator contacts, and the first and second electronic switching elements are electrically connected in series with each other. By means of the second electronic switching element, a safety switching circuit can be realized, which is designed to interrupt the electrical actuation of the actuator if the first electronic switching element is actuated incorrectly by means of the pulsed coupling signal. The signal generating unit can be realized, for example, by a program-controlled computing unit, in particular by a microcontroller/microprocessor, which provides the coupling signal to the first electronic switching element. In this case, the second electronic switching element can be actuated by a separate analog switching circuit, which therefore assumes the function of an electronic fuse. This prevents the actuator from being overloaded even if the program-controlled computing unit is halted, for example.

According to an advantageous embodiment of the door opener, the signal generating unit is designed to generate the coupling signal as a function of a current flowing through the actuator. The current through the actuator can thus be regulated by producing a desired temporal change (corresponding to a predefined setpoint value profile of the push-open force). In particular, influences caused by voltage fluctuations can be compensated for thereby.

According to an advantageous embodiment of the door opener, the signal generating unit is designed to generate the coupling signal as a pulse width modulated signal. The coupling signal is generated by means of a constant, predeterminable pulse period, i.e. by means of the inverse of the pulse width modulation frequency (PWM frequency), wherein a variable pulse width is provided. Here, the ratio of the pulse width to the pulse period is determined by a so-called duty cycle (english: duty cycle). Alternatively, a pulse train control can be provided, in which a constant, predeterminable on-time is set and the duty cycle is implemented by controlling the respective off-time. Likewise, a constant off-time can be set and the on-time varied in a corresponding manner.

Preferably, the duty cycle for each clock period can be implemented according to a so-called cyclic control. It can also be provided that the coupling signal is generated on the basis of a two-point regulator method in such a way that the coupling signal is switched on if the current through the actuator falls below a predeterminable minimum value and is switched off if the current through the actuator exceeds a predeterminable maximum value. In this case, the respectively effective minimum value and/or the respectively effective maximum value can be time-dependent. In this way, a particularly simple adjustment method can be achieved.

Preferably, a household appliance, in particular for the care of laundry, can have a door opening device according to the invention and a door which can be pressed out of a closed position by the door opening device, thereby obtaining a household appliance according to the invention. The door of the household appliance can be pushed open by the door opener with better temporal controllability and soft, improved properties. In this case, possible fluctuations in the input voltage, which is used as the supply voltage for the household appliance, can also be compensated for better. Additionally, use feedback can be provided which can be used to avoid a much stronger impact on the door when it has been opened. Overall, when the increase is performed slowly enough, no such additional impact occurs at all. Furthermore, absorption effects, which are produced by mechanical components of the household appliance, can be overcome. Longer pulses, for example in the case of using the entire pulse train, also mean that the door opener generates less noise. In particular when using a dc voltage as the internal supply voltage of the door opener, it is thus possible to achieve a supply frequency and a supply voltage which are independent of the supply voltage source on which the household appliance is operated.

Further features of the invention derive from the disclosure, the drawings and the description of the drawings. 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 in the figures individually can be used not only in the respectively indicated combination but also in other combinations without departing from the framework of the invention. Thus, the following embodiments can also be considered to be encompassed and disclosed by the present invention: the embodiments are not explicitly shown and explained in the figures, but can be derived and produced from individual combinations of features from the explained embodiments. The following embodiments and combinations of features can also be considered disclosed: the embodiments and feature combinations thus do not have all of the features originally listed. Furthermore, the following embodiments and combinations of features are to be regarded as disclosed, in particular, for the embodiments set forth above: the embodiments and feature combinations exceed or deviate from the feature combinations explained in the present disclosure.

Drawings

Further advantages and features result from the following description of embodiments, taking into account the drawings. In the drawings, like reference numerals refer to like features and functions.

The figures show:

fig. 1 a household appliance according to the invention in a simplified schematic front view;

fig. 2 shows, in a simplified schematic representation, a circuit arrangement for operating a door opener (as is arranged in the household appliance according to fig. 1);

fig. 3 is a modification of the circuit arrangement shown in fig. 2 in a simplified schematic representation, for use in a door opener according to the invention according to a preferred first embodiment; and

fig. 4 shows a preferred second embodiment of the door opener according to the invention in a simplified schematic representation.

Detailed Description

Fig. 1 shows a household appliance 1 for the care of laundry. The household appliance can be a washing machine, a laundry dryer or a combination appliance consisting of a washing machine and a laundry dryer. In the embodiment shown, this relates to a so-called front end loader having a door 2 that opens forward for closing a loading opening 3 that is, for example, circular. The household appliance 1 comprises a housing 4 in which a drum 5 for receiving laundry is arranged. The loading opening 3 is an opening on the front side of the drum 5. Furthermore, the household appliance 1 comprises an operating device 6, which is understood merely by way of example and not by way of limitation in terms of configuration and position, having at least one operating element 7 and a display unit 8. Furthermore, a slide-in type punch-through housing 9 is shown.

The pivotably arranged and in particular porthole-type door 2 is in mechanical contact with a door opener 10 arranged in the domestic appliance 1. In this embodiment, the door opening device 10 is arranged such that it can act on the inside of the edge piece of the door 2. This edge part lies opposite a further edge part of the door 2, on which further edge part the door 2 is pivotably mounted on the household appliance 1 by means of a hinge not shown in fig. 1.

The door opener 10 comprises an electromechanical actuator 11 having an electromagnetic coil and an actuator element which is mounted so as to be movable in the region of action of a magnetic field which can be generated by the electromagnetic coil and which is made of a magnetic or magnetizable material, preferably a ferromagnetic material. The door opener 10 further comprises a signal generating unit 12, which is designed to provide a pulsed coupling signal to an electrical coupling device 13, which effects an electrical actuation of the electromechanical actuator 11.

When the correspondingly provided program for treating the laundry is finished, opening of the door 2 by means of the door opening device 10 can be effected automatically at the end of the washing or drying process. Alternatively or additionally, it can be provided that: when a user of the household appliance 1 performs a corresponding operating process by means of an operating device, for example by pressing a button on the operating device 6 or by input via an input element on a touch screen (for example on the display unit 8), the door 2 of the household appliance 1 is opened by the door opener 10.

Fig. 2 shows an electrical part of the door opener 10, which can be inserted into the household appliance 1 according to the illustration in fig. 1. The door opener 10 comprises a supply connection 16 and a reference connection 17. The reference terminal 17 can be electrically connected to a neutral conductor terminal (N) of a supplied alternating voltage or three-phase power supply. The supply connection 16 can be electrically connected to an alternating voltage supply or to an outer conductor connection (L) of a three-phase power supply. This type of arrangement can be powered with a voltage of 230 volts and a frequency of 50 hertz. A first actuator connection 14 of the two actuator connections 14, 15 is electrically conductively connected to a supply connection 16. The second actuator terminal 15 of the two actuator terminals 14, 15 is electrically coupled to the reference terminal 17 via an electrical coupling device 13 in the form of a first switching element 21, which is designed as a Triac.

A supply voltage 18 acts between the supply connection 16 and the reference connection 17, said supply voltage having a sinusoidal course. The supply voltage relates in particular to a voltage of 230 volts with a supply frequency of 50 hz. The electrical actuation of the actuator 11, which is represented by its solenoid in the illustration in fig. 2, is effected by means of a pulsed coupling signal 19. The current through the electromagnetic actuator is schematically shown as actuator current 20. The actuator current 20 has not only positive but also negative half waves, the amplitude of which are respectively equal. In the case of an actuator element in the form of a ferromagnetic element whose pulling force is based on the reluctance force, a pulling force is generated which is proportional to the square of the actuator current 20. For this reason, irrespective of the instantaneous flow direction of the actuator current 20, an unsigned change in the pressing-open force transmitted by the actuator element to the door 2 by means of the push rod is produced. Referring to the diagram in fig. 2, only the successive positive half waves are thereby generated for a change in the push-open force.

The electromagnetic coil of the actuator 11 is therefore actuated electrically by means of an Alternating Current (AC), which is shown for the sake of clarity in the figure as three half cycles, and which must already provide the force required for opening within 10 milliseconds during the first half cycle, that is to say at a supply frequency of 50 hz. In other words, within a half-cycle, i.e. within 10 milliseconds, the total energy (W) results from the multiplication of half the inductance (L) of the coil by the square of the current (I) through the actuator 11 (W: 1/2 · L · I)²) Said half inductance depends in that respect on the position of the movable actuator element relative to the electromagnetic coil of the actuator 11. The energy in the solenoid coil is then not increased further, so that this also does not result in a further increase in the force for the displacement force.

This short time has several disadvantages. In one aspect, the effective pulse duration is frequency dependent. If the solenoid coil remains activated for a longer period of time, vibration may occur due to the crossing of the actuator current 20 at the phase of 0 degrees and 180 degrees. The door 2, the household appliance 1 and the door holding mechanism are mechanical parts connected to each other. They may absorb the impact of the impact, which is rapidly applied by the door opener, having a duration in the range of 10 milliseconds or less to the greatest extent, since they act as mechanical filters. Thus requiring a large pulse. Furthermore, voltage fluctuations can lead to different pressing forces, since here different energies are supplied to the magnet coil within 10 milliseconds, so that a fine adjustment of the voltage between 170 volts and 260 volts cannot be carried out. Therefore, to ensure that door 2 is also open at all times at 170 volts AC, a strong impact at 260 volts AC must be allowed. The pulse width of the pulsed coupling signal 19 for actuating the first switching element 21 in the form of a triac is understood in fig. 2 only as a representative and not limiting way.

In order to achieve a temporal change in the pressing-off force with a rising envelope curve, according to the first exemplary embodiment of the invention, which is illustrated in fig. 3, a resistor element 22 in the form of a thermistor with a temperature-dependent resistance value with a negative temperature coefficient, which is additionally connected electrically in series to the actuator 11, is also provided in the electrical part of the door opener 10. The resistance element 22 is therefore connected between the first actuator connection 14 and the supply connection 16 and, according to the illustration of fig. 2, occurs at the location of the direct electrical connection between the first actuator connection 14 and the supply connection 16.

In principle, in the case of the door opener 10 according to the diagram of fig. 3, vibrations based on the system frequency and the mechanical properties also occur in the case of a longer activation duration of the actuator. Such a tendency to vibrate can be reduced by coupling the electromagnetic coil of the actuator 11 through a full-wave rectifier (bridge rectifier). In this case, it is also possible to integrate a smoothing filter element (for example a capacitor) after the rectifier, in order thereby to achieve a filtering of the supply frequency part from the excitation signal.

The NTC takes some time to cool down again, which results in the system working less efficiently for the case where the door 2 is to be opened twice in a short time. In this case, the second embodiment shown next provides a more efficient way to operate the door opener 12 by means of a circuit arrangement that supplies a direct voltage.

According to a second embodiment of the invention, which corresponds to the diagram in fig. 4, a dc voltage is connected as supply voltage 18 to supply terminal 16 and reference terminal 17. Here, the preferred supply voltage 18 can be 175 volts DC to 400 volts DC. These values are not to be understood in a limiting manner, but rather arbitrary voltage levels, in particular also voltage levels of less than 175 volts DC, can be set. In the second exemplary embodiment shown, the coupling device 13, which is coupled in series in a known manner to the electromechanical actuator 11, has a first switching element 21 and a second switching element 24, which are connected in series to one another. The first switching element 21 and/or the second switching element 24 can be realized as bipolar transistors. In parallel with the solenoid of the actuator 11, a freewheeling diode 23 is coupled to the first actuator terminal 14 and the second actuator terminal 15.

The freewheeling diode 23 serves to prevent overvoltage peaks which would otherwise occur when the first switching element 21 and/or the second switching element 24 are switched off. The first switching element 21, which is currently implemented as a bipolar transistor, receives the pulsed coupling signal 19 at its base terminal. In the second embodiment, the pulsed coupling signal 19 is designed as a pulse width modulated signal (PWM signal). In each case, the coupling signal 19 has a higher pulse width in the following clock cycle than in the preceding clock cycle. Thereby producing an actuator current 20 having a rising envelope curve. From the functional relationship of the opening force with respect to the actuator current 20 (for example the proportional relationship to the square of the actuator current 20 shown above), a rising envelope curve is also obtained for the temporal change of the opening force.

The second switching element 24 represents a safety switching circuit (PEC). The manner in which this second switching element 24 is implemented is not significant to the present invention.

The interrelationship between the actuator current 20 and the resulting temporal variation of the push-open force can have very different characteristics depending on the manner in which the electromechanical actuator 11 is used. Thus, according to the second embodiment, the use of a pulsed coupling signal 19 consisting of a plurality of single pulses as a pulse train allows a freely adjustable adjustment of the curve change of the actuator current 20, which corresponds to the requirement for a change of the opening pressure to be adjusted. The dynamic behavior of the opening process can thereby be optimized with regard to safe and comfortable flow.

The circuit arrangement shown has some advantages during the opening of the door. It is possible to provide a pulse sequence with an increased pulse width onto the coupling means 13, for example with a continuous increase of the duty cycle (english: duty cycle) from 0% to 100%. Different boost curves can be generated depending on the circuit arrangement and the mechanical characteristics of the actuator 11, for example with a slight overshoot towards the end of the door opening process.

Likewise, the increased duty cycle can be adapted to the magnitude of the supplied direct voltage, which is obtained from the supplied alternating current source or the three-phase alternating current, for example for supplying further components of the household appliance 1, such as the drive motor or the heating device. Possible input voltage fluctuations can be compensated better.

The slow boosting characteristic helps to reduce the impression of sudden door strikes and also helps to reduce noise generation. If the increase is made sufficiently slowly, no such additional shock occurs.

If the increase is carried out slowly so that the door opening signal (feedback signal) can additionally be detected, the door opening device can be immediately deactivated in order to avoid a much stronger additional impact on the door which has then been opened via the door holding mechanism.

The first embodiment of the invention can be implemented in a very simple manner, while the second embodiment offers a much higher degree of flexibility and in particular also achieves independence from the supply frequency and the supply input voltage.

The embodiments are merely intended to illustrate the invention without limiting it, and in particular the specific configuration of the components of the circuit technology with which the invention is implemented can be constructed at will, without leaving the inventive idea.

It has therefore been described above how a door opener 10 as shown in the second embodiment, in particular a door opener 10 operated by means of a dc voltage, can be configured in order to improve the safety and comfort during the opening of a door by a household appliance. In addition to the DC-based activation of the door opener 10, an improved AC-based activation of the door opener 10 is also proposed.

List of reference numerals

1 household appliance

2 door

3 loading opening

4 casing

5 roller

6 operating device

7 operating element

8 display unit

9 punch-in shell

10 door opener

11 electromechanical actuator

12 Signal generating unit

13 electric coupling device

14 first actuator joint

15 second actuator joint

16 supply connection

17 reference joint

18 supply voltage

19 pulsed coupled signals

20 actuator current

21 first switching element

22 resistive element, variable

23 no-load diode

24 second switching element

Claims (15)

1. Method for operating a door opener (10) of a household appliance (1) comprising a door (2) during an opening process, the door opener comprising an electromechanical actuator (11), wherein the actuator (11) comprises two actuator contacts (14, 15) for an electrical operation, the method comprising:

-providing a supply voltage (18) between an electrical supply connection (16) and an electrical reference connection (17) of the door opening device (10), said supply voltage having a voltage form predefined in a specific operating state of the household appliance (1),

-providing an electric coupling means (13) for coupling a first of the two actuator connections (14, 15) to the electric supply connection (16) and/or a second of the two actuator connections (14, 15) to the electric reference connection (17) on demand,

-coupling the supply voltage (18) to the two actuator connections (14, 15) by means of the coupling device (13) as a function of a pulsed coupling signal (19) for electrically actuating the actuator (11), and

-generating a press-open force for acting on the door (2) according to an electric actuation of the actuator (11),

the method is characterized in that:

-generating the pulsed coupling signal (19) as a function of the predefined voltage profile and/or as a function of a provided coupling device (13) in order to achieve a temporal change in the opening pressure, which has a rising envelope curve,

wherein the electric coupling device (13) has a resistance element (22) which is electrically connected in series to the actuator (11) and has a variable resistance.

2. Method according to claim 1, characterized in that providing the coupling means (13) and generating the pulsed coupling signal (19) are implemented as: during an activation pulse phase of the pulsed coupling signal (19), the temporal change of the press-on force has a sequence of at least two local maxima, which are located respectively on or in the vicinity of the rising envelope curve, wherein a second local maximum of the at least two local maxima, which immediately follows a first local maximum of the at least two local maxima in time, has a greater value than the first local maximum.

3. Method according to claim 2, characterized in that providing the coupling means (13) and generating the pulsed coupling signal (19) are implemented as: such that the sequence of at least two local maxima has a third local maximum immediately after the second local maximum in time, the third local maximum having a larger value than the second local maximum.

4. Method according to any of the preceding claims, characterized in that the supply voltage (18) is provided by a direct current power supply.

5. A method according to any one of claims 1 to 3, characterized in that the supply voltage (18) is provided by an alternating current source.

6. Method according to one of claims 1 to 3, characterized in that the pulsed coupling signal (19) during the opening process is generated in a sequence of a plurality of single pulses spaced apart from one another in time.

7. Method according to claim 5, characterized in that the pulsed coupling signal (19) during the opening process is generated in a single pulse.

8. Method according to any of claims 1 to 3, characterized in that the pulsed coupling signal (19) is generated as a function of a first signal representing the open state of the door (2) and/or as a function of a second signal representing the locked state of the door (2).

9. A door opening device (10) in a household appliance (1) comprising a door (2), wherein the door opening device (10) comprises:

an electrical supply connection (16) and an electrical reference connection (17), between which a supply voltage (18) can be provided, said supply voltage having a voltage form predefined in a specific operating state of the household appliance (1),

-an electromechanical actuator (11) for generating a pressure opening force for acting on the door (2) in accordance with an electric actuation of the actuator (11), the actuator comprising two actuator contacts (14, 15) for the electric actuation, and

-an electric coupling device (13) which is designed to couple a first of the two actuator connections (14, 15) to the electric supply connection (16) and/or a second of the two actuator connections (14, 15) to the electric reference connection (17) in order to electrically actuate the actuator (11) as a function of a pulsed coupling signal (19)

The method is characterized in that:

-the door opener comprises a signal generating unit (12) which is designed to generate the pulsed coupling signal (19) as a function of the predefined voltage profile and/or as a function of the coupling device (13) in order to achieve a temporal change in the pressing-open force with a rising envelope curve,

wherein the electric coupling device (13) has a resistance element (22) which is electrically connected in series to the actuator (11) and has a variable resistance.

10. Door opener (10) according to claim 9, characterized in that the electric coupling device (13) has a first electronic switching element (21) which is connected electrically in series to the actuator (11).

11. Door opener (10) according to claim 10, characterized in that the electric coupling device (13) has a second electronic switching element (24) which is connected electrically in series to the first electronic switching element (21).

12. The door opener (10) according to one of claims 9 to 11, characterized in that the signal generation unit (12) is designed to generate the pulsed coupling signal (19) as a function of the current through the actuator (11).

13. The door opener (10) according to one of claims 9 to 11, characterized in that the signal generation unit (12) is designed to generate the pulsed coupling signal (19) as a pulse width modulated signal.

14. A household appliance (1) having a door opening device (10) according to one of claims 9 to 13 and having a door (2) which can be pressed open from a closed position by the door opening device (10).

15. The household appliance (1) according to claim 14, wherein the household appliance (1) is a household appliance for caring for laundry.

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