EP3126763B1 - Domestic appliance with a pivotal panel, and method for operating a domestic appliance with a pivotal panel - Google Patents

Description

The invention relates to a household appliance, which has a reference to a pivot axis pivotable flap. The invention also relates to a method for operating a household appliance with a pivotable flap.

For example, household refrigerators comprise a pivotable with respect to a pivot axis flap, which close in a first position, an opening and opens in a second position. The flap can be pivoted by means of an adjusting device between the two positions back and forth. Adjustment devices of conventional household refrigerators or generally conventional household appliances comprise a synchronous or stepping motor.

The WO 91/15724 A1 discloses a home appliance designed as a domestic refrigeration appliance, which has a relative to a pivot axis between at least two positions pivotally arranged flap and an adjusting device which is adapted to pivot the flap between the at least two positions back and forth. The adjusting device comprises a wire coupled to the flap of a shape memory alloy, which shortens when heated and thereby pivots the flap from a first position to a second position.

The object of the present invention is to specify a domestic appliance, in particular a household refrigerating appliance, which has a flap which can be pivoted relative to a pivot axis and an improved adjusting device for pivoting the flap between at least two positions.

The object of the invention is achieved by a household appliance according to claim 1. The household appliance according to the invention is in particular a household refrigerator, such as a household refrigerator or a Haushaltsgefriergerät. Preferably, the household appliance according to the invention is a household refrigerator with at least two temperature zones of different temperatures, such as a fridge-freezer.

The household appliance according to the invention accordingly comprises the flap pivotable relative to the pivot axis and the adjusting device for pivoting the flap so that it can assume at least two different positions. According to the invention the adjusting device comprises the wire of a shape memory alloy. Shape memory alloys are also referred to as "memory metals". The shape memory alloy wire is such that it contracts when heated, thus shortens its length, thereby pivoting the flap from its first position to its second position. In particular, the shape memory alloy wire is such as to be cool in its cooled state by application of a force e.g. comes from a preloaded spring, pull back to its original length. This makes it possible, in particular, for the flap to pivot back into the first position. Upon pivoting from the first position to the second position, the shape memory alloy wire contracts to override the spring force applied by the biased spring.

In order to heat the wire from a shape memory alloy, the adjusting device of the household appliance according to the invention may comprise an electrical energy source, by means of which the wire of a shape memory alloy can be acted upon with electrical energy. If the wire made of a shape memory alloy is subjected to electrical energy, so that in particular an electric current flows through it, then it heats up. The electrical energy source is e.g. an electrical voltage source whose electrical voltage is e.g. at the ends of the wire is made of a shape memory alloy. The electrical energy source is e.g. from a control device of the household appliance on and off. When the electrical energy source is switched off, the wire can cool down from a shape memory alloy.

The shape memory alloy wire has two ends which secure the shape memory alloy wire spaced from the pivot axis to a fixed part of the household appliance. The wire of a shape memory alloy is additionally fastened at a distance from the pivot axis on the flap by means of a fastening device. In particular, the runs Connecting line between those points at which the ends of the wire of a shape memory alloy are fixed to the stationary part of the household appliance, parallel to the pivot axis. According to this embodiment, it is possible, for example, that the fastening device has a groove directed away from the pivot axis, in which the wire is guided by a shape memory alloy. As a result, the shape memory alloy wire is movable along this groove, thereby at least reducing the risk of tearing when the wire is made of a shape memory alloy that is unevenly contracted.

According to a variant of the household refrigerating appliance according to the invention, it is provided that seen from above, the wire of a shape memory alloy is attached to the flap between its ends by means of the fastening device, in particular centrally with respect to its ends, on the flap by means of the fastening device. This results in a V-shaped arrangement of the wire of a shape memory alloy, whereby the portions of the wire of a shape memory alloy, which extend from the fastening device to the respective ends, are the same length. This makes it possible that these two sections pull together when heated by the same length, which in turn has a positive effect on the load

The flap can be e.g. extend along the pivot axis by one width. Preferably, the length of the connecting line between those locations where the ends of the shape memory alloy wire are attached to the fixed part of the household appliance is greater than or equal to the width of the flap. In particular, the fastening device is arranged centrally with respect to the width of the flap on the flap. of the wire from a shape memory alloy.

The fastening device comprises a flapper-mounted pocket having an opening facing away from the pivot axis and a spring-biased element within the pocket to which the shape memory alloy wire is attached, the spring-biased element being biased to form the shape memory alloy wire away from the pivot axis. The bag is preferably integrally formed on the flap. Since, according to the invention, the wire of a shape memory alloy is fastened to the spring-biased element, this can give way, for example, the flap should be jammed or frozen in the case of household refrigeration appliance.

Preferably, the spring biased member has a groove which opens away from the pivot axis and in which the wire is guided by a shape memory alloy. As a result, the shape memory alloy wire is movable along this groove, thereby at least reducing the risk of tearing when the wire is made of a shape memory alloy that is unevenly contracted.

The household appliance according to the invention may have an opening which is closed by the flap when the flap is in its first position and which is open when the flap is in its second position.

Preferably, the household appliance according to the invention may be designed as a household refrigerating appliance which has at least two temperature zones of different temperature, wherein the opening connects a first temperature zone of the temperature zones with a second temperature zone of the temperature zones so that cooled air can flow between the first temperature zone and the second temperature zone, when the flap is in its second position. According to this embodiment, the domestic appliance embodied as a household refrigerating appliance comprises at least the first and the second temperature zones, which are to be cooled to different temperatures during operation of the household refrigerating appliance. The two temperature zones are connected by means of the opening, so that cooled air can flow from the colder temperature zone into the warmer temperature zone when the flap is open. An example of a household refrigerator with at least two temperature zones of different temperature is a fridge-freezer with a coolable interior and a freezer compartment. Then this opening can connect the coolable interior with the freezer compartment, so that cooled air can flow from the freezer compartment to the coolable compartment when the flap is in its second position, ie is open. As a result, for example, the cost of a coolant circuit, which is provided for cooling the freezer compartment and the coolable interior, can be reduced. The flap can then eg by a control device the refrigerator-freezer combination are controlled, so that the coolable interior is cooled over the freezer compartment and at least approximately has a desired temperature.

According to a preferred variant of the household appliance according to the invention, the adjusting device has a bi-stable mechanism coupled to the flap, which has a prestressed spring which is pretensioned in such a way that it attempts to pivot the flap into its first position. The bi-stable mechanism is configured to assume a first stable state, a second stable state, a first unstable state, and a second unstable state, wherein the first stable state is associated with the first position and the second stable state is associated with the second position with the flap. such that the bi-stable mechanism in its first stable state holds the flap in its first position and in its second stable state in its second position, and the biased spring attempts in the first unstable state to bi-stable the mechanism to its second stable state to move to its first stable state in the second unstable state. As already explained, the flap is pivoted from its first state to its second state by heating the shape memory alloy wire. In order to pivot the flap back into its first position, the wire is cooled from a shape memory alloy and can therefore be pivoted, for example by means of a prestressed spring back into the first position. However, in order not to have to heat the flap constantly during its second position, the bi-stable mechanism is provided according to this variant, which holds in its second stable state, the flap in its second position even with cooled wire from a shape memory alloy and prestressed spring. The bi-stable mechanism can take the two unstable states in addition to the two stable states, wherein in the first unstable state, the biased spring tries to pivot the flap towards the first position, so that when cooled wire from a shape memory alloy bi-stable mechanism its second stable state and thus holds the flap in its second position, as long as the wire is not heated from a shape memory alloy. In the second unstable state, the preloaded spring also attempts to pivot the flap toward the first position so that when the shape memory alloy wire is cold, the bi-stable mechanism assumes its first stable state and thus holds the flap in its first position while the wire is off a shape memory alloy is not heated.

• die vorgespannte Feder, die derart vorgespannt ist, dass sie versucht, die Klappe in ihre erste Stellung zu schwenken,
• ein Bauelement mit einer Oberfläche, die zumindest in etwa rechtwinklig zur Schwenkachse ausgerichtet und in der eine nutförmig verlaufende herzförmige Kontur angeordnet ist, wobei das Bauelement Teil der Klappe oder mit dieser starr verbunden ist und somit das Bauelement und die herzförmige Kontur mit der Klappe mit schwenkt und der herzförmigen Kontur die beiden stabile Zuständen und die beiden instabilen Zustände zugeordnet sind,
• ein in der herzförmigen Kontur eingreifender Stift, der derart mit der herzförmigen Kontur zusammenwirkt, sodass der Stift die Klappe in ihrer ersten Stellung hält, wenn der bi-stabile Mechanismus seinen ersten stabilen Zustand aufweist und die Klappe in ihrer zweiten Stellung hält, wenn der bi-stabile Mechanismus seinen zweiten stabilen Zustand aufweist.

Nach dieser Variante des erfindungsgemäßen Haushaltsgerätes umfasst demnach der bi-stabile Mechanismus das Bauelement, in der eine Nut eingebracht ist, die herzförmig verläuft. Dieses Bauelement ist beispielsweise Teil der Klappe, z.B. an dieser einstückig angeformt oder die herzförmige Kontur ist in einer rechtwinklig zur Schwenkachse ausgerichteten Oberfläche der Klappe angeordnet. Das Bauelement kann aber auch starr mit der Klappe verbunden sein. Die herzförmige Kontur schwenkt somit mit der Klappe mit. Mit der herzförmigen Kontur wirkt der Stift zusammen, indem er in die herzförmige Kontur eingreift und das Bauelement und somit die Klappe in den stabilen Zustanden hält.According to a preferred variant of the household appliance according to the invention, the bi-stable mechanism comprises the following constituents:

• the biased spring biased to attempt to pivot the flap to its first position,
• a component having a surface which is aligned at least approximately at right angles to the pivot axis and in which a groove-shaped heart-shaped contour is arranged, wherein the component part of the flap or is rigidly connected thereto and thus pivots the component and the heart-shaped contour with the flap and the heart-shaped contour are associated with the two stable states and the two unstable states,
• an engaging in the heart-shaped contour pin, which cooperates with the heart-shaped contour, so that the pin holds the flap in its first position when the bi-stable mechanism has its first stable state and holds the flap in its second position when the bi -stable mechanism has its second stable state.

According to this variant of the household appliance according to the invention accordingly comprises the bi-stable mechanism, the component in which a groove is introduced, which extends heart-shaped. This component is for example part of the flap, for example integrally formed on this or the heart-shaped contour is arranged in a direction perpendicular to the pivot axis surface of the flap. The device may also be rigidly connected to the flap. The heart-shaped contour thus pivots with the flap. With the heart-shaped contour of the pin cooperates by engaging in the heart-shaped contour and holds the device and thus the flap in the stable states.

• Erwärmen des Drahtes aus einer Formgedächtnislegierung, sodass dieser sich verkürzt und gegen die Federkraft der vorgespannten Feder die Klappe von ihrer ersten Stellung über die zweite Stellung hinaus schwenkt, sodass der bi-stabile Mechanismus seinen ersten instabilen Zustand einnimmt, und
• Abkühlen lassen des Drahts aus einer Formgedächtnislegierung, sodass die vorgespannte Feder die Klappe in Richtung der ersten Stellung der Klappe zu schwenken vermag bis der bi-stabile Mechanismus seinen zweiten Zustand erreicht und die Klappe ihre zweite Stellung einnimmt.

Der Draht aus einer Formgedächtnislegierung wird insbesondere durch Einschalten der elektrischen Energiequelle erwärmt. Durch das Erwärmen zieht sich der Draht aus einer Formgedächtnislegierung zusammen und schwenkt gegen die Federkraft der vorgespannten Feder die Klappe in Richtung zweite Stellung und darüber hinaus, bis der bi-stabile Mechanismus seinen ersten instabilen Zustand erreicht. Daraufhin wird insbesondere die elektrische Energiequelle ausgeschaltet, wodurch sich der Draht aus einer Formgedächtnislegierung abkühlt und mittels der vorgespannten Feder in Richtung seiner ersten Stellung geschwenkt wird. Der bi-stabile Mechanismus, insbesondere die herzförmige Kontur wird entsprechend mit geschwenkt und geht in ihren zweiten stabilen Zustand über, in dem insbesondere der Stift das Bauelement und somit die Klappe in der zweiten Stellung hält und somit ein weiteres Schwenken der Klappe in ihrer ersten Stellung verhindert. Der Draht aus einer Formgedächtnislegierung ist dabei abgekühlt bzw. die elektrische Energiequelle ausgeschaltet.A further aspect of the invention accordingly relates to a method for operating the household appliance according to the invention, comprising the following method steps:

• Heating the wire from a shape memory alloy so that it shortens and pivots against the spring force of the biased spring, the flap from its first position beyond the second position, so that the bi-stable mechanism assumes its first unstable state, and
• Allow the shape memory alloy wire to cool allowing the biased spring to close the flap toward the first position of the flap can pivot until the bi-stable mechanism reaches its second state and the flap assumes its second position.

The wire of a shape memory alloy is heated in particular by switching on the electrical energy source. Upon heating, the shape memory alloy wire contracts and, against the spring force of the biased spring, pivots the flap toward the second position and beyond until the bi-stable mechanism reaches its first unstable state. Then, in particular, the electrical energy source is turned off, whereby the wire cools from a shape memory alloy and is pivoted by means of the prestressed spring in the direction of its first position. The bi-stable mechanism, in particular the heart-shaped contour is pivoted in accordance with and goes into its second stable state in which in particular the pin holds the component and thus the flap in the second position and thus further pivoting of the flap in its first position prevented. The wire made of a shape memory alloy is cooled or turned off the electrical energy source.

• Erwärmen des Drahtes aus einer Formgedächtnislegierung, sodass dieser sich verkürzt und gegen die Federkraft der vorgespannten Feder die Klappe von ihrer zweiten Stellung über die zweite Stellung hinaus schwenkt, sodass der bi-stabile Mechanismus seinen zweiten instabilen Zustand einnimmt, und
• Abkühlen lassen des Drahts aus einer Formgedächtnislegierung, sodass die vorgespannte Feder die Klappe in Richtung der ersten Stellung der Klappe zu schwenken vermag bis der bi-stabile Mechanismus seinen ersten Zustand erreicht und die Klappe ihre erste Stellung einnimmt.

Der Draht aus einer Formgedächtnislegierung wird insbesondere durch Einschalten der elektrischen Energiequelle erwärmt. Durch das Erwärmen zieht sich der Draht aus einer Formgedächtnislegierung zusammen und schwenkt gegen die Federkraft der vorgespannten Feder die Klappe über die zweite Stellung hinaus, bis der bi-stabile Mechanismus seinen zweiten instabilen Zustand erreicht. Daraufhin wird insbesondere die elektrische Energiequelle ausgeschaltet, wodurch sich der Draht aus einer Formgedächtnislegierung abkühlt und die Klappe mittels der vorgespannten Feder in Richtung seiner ersten Stellung geschwenkt wird. Der bi-stabile Mechanismus, insbesondere die herzförmige Kontur wird entsprechend mit geschwenkt und geht wieder in ihren ersten stabilen Zustand über, in dem insbesondere der Stift das Bauelement und somit die Klappe in der ersten Stellung hält, solange der Draht aus einer Formgedächtnislegierung abgekühlt ist. Der Draht aus einer Formgedächtnislegierung ist dabei abgekühlt bzw. die elektrische Energiequelle ausgeschaltet.If now the flap is to be pivoted from its second position to its first position, the following additional method steps can be carried out:

• Heating the wire from a shape memory alloy so that it shortens and pivots against the spring force of the biased spring, the flap from its second position beyond the second position, so that the bi-stable mechanism assumes its second unstable state, and
• Allowing the shape memory alloy wire to cool allowing the biased spring to pivot the flap toward the first position of the flap until the bi-stable mechanism reaches its first state and the flap assumes its first position.

The wire of a shape memory alloy is heated in particular by switching on the electrical energy source. Upon heating, the shape memory alloy wire contracts and pivots the flap past the second position against the spring force of the biased spring until the bi-stable mechanism reaches its second unstable state. Then, in particular, the electrical energy source is turned off, whereby the wire cools from a shape memory alloy and the flap is pivoted by means of the prestressed spring in the direction of its first position. The bi-stable mechanism, in particular, the heart-shaped contour is pivoted in accordance with and returns to its first stable state, in particular, the pin holds the device and thus the flap in the first position, as long as the wire is cooled from a shape memory alloy. The wire made of a shape memory alloy is cooled or turned off the electrical energy source.

Depending on the embodiment of the invention, this therefore relates to a pivotable flap, insbesondre air damper, with an SMA actuator (SMA = Shape Memory Alloy, English for shape memory alloy). The flap with the Aktiuator is used in particular for an improvement of the air damper for controlling the air flow in so-called No Frost devices. The flap, in particular the air flap, is preferably pivoted with a V-shaped SMA wire as an actuator between the two positions. The wire of a shape memory alloy is thereby preferably fastened in V-shape to the flap. For example, when energizing the wire of a shape memory alloy, this heats up, shortens and pulls the flap in particular against a spring force in the direction of the second position. The attachment of the shape memory alloy wire is accomplished, for example, by crimping the shape memory alloy wire with another wire, e.g. a stainless steel wire, which may possibly simultaneously represent the electrical connection of the optionally existing electrical energy source. The pivot axis of the flap may preferably be connected to a bi-stable mechanism. This is actuated when the flap is pivoted towards its second position, e.g. the pen, e.g. a metal pin, into the intended opening of a heart curve locks.

Due to the use of the wire of a shape memory alloy, a relatively quiet, if not silent, actuator can be provided. As a result, the pivoting of the flap can be relatively quiet, if not silent. There may be a relatively low energy consumption for pivoting the flap. The structure is relatively simple.

Figur 1

ein Haushaltskältegerät,

Figuren 2 und 3

eine schwenkbare Klappe des Haushaltskältegerätes und eine Verstellvorrichtung, welche eingerichtet ist, die Klappe zwischen zwei Stellungen hin und her zu schwenken,

Figur 4

einen bi-stabilen Mechanismus der Verstellvorrichtung, und

Figur 5

mehrere Zustände des bi-stabilen Mechanismus.

An embodiment of the invention is illustrated by way of example in the accompanying schematic drawings. Show it:

FIG. 1

a household refrigerator,

FIGS. 2 and 3

a hinged flap of the household refrigerating appliance and an adjusting device which is arranged to pivot the flap back and forth between two positions,

FIG. 4

a bi-stable mechanism of the adjustment, and

FIG. 5

several states of the bi-stable mechanism.

The Fig. 1 shows as an example of a household appliance, a household refrigerator 1. The household refrigerator 1 is in the case of the present embodiment, a so-called no-frost household refrigerator. The household refrigerator 1 is in particular a fridge-freezer.

In the case of the present exemplary embodiment, the household refrigerating appliance comprises a heat-insulated housing 2 with an inner container which delimits a coolable interior space 3 and a freezer space 4 arranged underneath. The coolable interior 3 is separated by a heat-insulated partition 5 from the freezer compartment 4. The coolable interior 3 is provided for storing refrigerated goods and is cooled during operation of the household refrigerator 1 to temperatures above freezing. The freezer compartment 4 is provided for storing frozen food and is cooled during operation of the household refrigerator 1 to temperatures below freezing.

In the case of the present exemplary embodiment, the household refrigerating appliance 1 has a pivotable door leaf 6 for closing the coolable interior 3 and a pivotable door leaf 7 for closing the freezer compartment 3. When the door leaves 6, 7 open the coolable interior 3 and the freezer compartment 4 are accessible.

The domestic refrigeration appliance 1 comprises in particular a refrigerant circuit not shown in detail for cooling the coolable interior 3 and the freezer compartment 4. The refrigerant circuit comprises eg a compressor, a condenser downstream of the compressor, a condenser downstream of the condenser and an evaporator connected between the throttle device and the compressor is arranged. in the In the case of the present exemplary embodiment, the evaporator is coupled directly to the freezer compartment 4 or is arranged on one of the walls directed towards the freezer compartment 4.

In the case of the present embodiment, an opening 8 is disposed within the partition wall 5, which by means of a in the Figures 2 and 3 shown flap 21 can be closed and opened. The opening 8 is surrounded in particular by means of a frame 22 and the flap 21 is pivotally mounted with respect to a pivot axis 23 and can by means of an adjusting device 9 between a first position in which the flap 21 closes the opening 8, and a second position in which the Flap 21 opens the opening 8, are pivoted back and forth. The flap 21 is preferably rectangular and has in particular a width b, which extends in the direction of the pivot axis 23, and a height h, which is aligned at right angles to the pivot axis 23.

With the flap 21 open, i. when this is in its second position, cooled air can flow from the freezer compartment 4 into the coolable interior 3 in order to cool it.

The household refrigerator 1 further comprises a control device 10, which is e.g. comprises a microprocessor or microcontroller and is adapted to control the refrigerant circuit and the adjusting device 9 for the flap 21 such that the coolable interior 3 and the freezer compartment 4 have at least approximately set temperature target values. The household refrigerating appliance 1 may have temperature sensors not shown in greater detail, which measure the actual temperatures of the coolable interior 3 and the freezer compartment 4.

In the case of the present embodiment, the adjusting device 9 comprises a wire 24 made of a shape memory alloy. The fact that the wire 24 is made of a shape memory alloy, this contracts when heated together, ie shortens its length when heated. Cools the wire 24 from a shape memory alloy, then this can be stretched again, for example by means of a biased spring 45 in its original length. To heat the wire 24 from a shape memory alloy, this is in the case of the present Embodiment electrically energized by the wire 24 is made of a shape memory alloy, for example, an electrical voltage applied or the wire 24 is made of a shape memory alloy with an electric current. For this purpose, the household refrigerating appliance 1 may comprise a voltage source (not shown in more detail) which can be activated by means of the control device 10 and connected to the wire 24 made of a shape memory alloy.

In the case of the present embodiment, the wire 24 made of a shape memory alloy with its two ends spaced from the pivot axis 23 on the frame 22 in particular near the region of the flap 21 is fixed, which faces the pivot axis 23. In particular, the two ends of the shape memory alloy wire 24 are secured to the frame 22 near those edges of the flap 21 which face the pivot axis 23. In particular, the connecting line between those points at which the ends are fixed to the frame 22, parallel to the pivot axis 23. In particular, the ends of the wire 24 are crimped from a shape memory alloy for their attachment to a further wire not shown in detail, which at the same time Connections for the voltage source can be.

Further, the shape memory alloy wire 24 is secured to the flap 21 such that when it is heated, its contraction pivots the flap 21 from its first position to its second position. For this purpose, in the case of the present embodiment of the wire 24 is made of a shape memory alloy approximately centrally with respect to the width b of the flap 21 and spaced from the pivot axis 23 attached to the flap 21. In particular, the wire 24 made of a shape memory alloy is fastened to the flap 21 approximately at half the height h. As a result, the shape memory alloy wire 24 has a V shape.

In the case of the present embodiment, the shape memory alloy wire 24 is fixed to the flap 21 by means of a fixing device 25. The fastening device 25 is designed in two parts in the case of the present exemplary embodiment and comprises a pocket 26 fastened to the flap 21 with an opening 27 facing away from the pivot axis 23. The fastening device 25 further comprises a guided inside the pocket 26 spring biased member 28 having a groove 29 within which the wire 24 is guided from a shape memory alloy. The spring biased member 28 is biased to urge the shape memory alloy wire 24 away from the pivot axis 23. The region of the spring-biased element 28, which has the groove 29, is located outside the pocket 26. The groove 29 is opened away from the pivot axis 23. The pocket 26 and the spring-biased element 28 are preferably made of plastic. The pocket 26 is preferably integrally formed on the flap 21 or is preferably part of the flap 21st

In the case of the present embodiment, the adjusting device 9 comprises a in the Fig. 4 shown in a perspective view bi-stable mechanism 41. Different states of the bi-stable mechanism 41 are in the FIGS. 5a-d shown.

The bi-stable mechanism 41 is coupled to the flap 21 and is designed to have one in the Fig. 5a shown first stable state, one in the Fig. 5c second stable state, one in the Fig. 5b first unstable state and one in the Fig. 5d having shown second unstable state. The bi-stable mechanism 41 is coupled to the flap 21 so as to allow closure of the opening 8 in its first stable condition of the flap 21 so that it is pulled by the prestressed spring 45 when the shape memory alloy wire 24 has cooled first position. In its second stable state, the bi-stable mechanism 41 holds the flap 21 in its second position so that the flap 21 opens the aperture 8.

In the case of the present exemplary embodiment, the bi-stable mechanism 41 comprises a component 42 which is rigidly or rigidly coupled to the flap 21 and has a surface 43 which is aligned at least approximately at right angles to the pivot axis 23. In the surface 43 a groove-shaped heart-shaped contour 44 is arranged. The component 42 is preferably fixed and rigidly attached to the flap 21. It may also be part of the flap 21. Characterized in that the device 42 is rigidly connected to the flap 21 or even part of the flap 21, the component 42 pivots with a movement of the flap 21 with this.

The bi-stable mechanism 41 further includes the biased spring 45 which is coupled to the member 42 or the flap 21. The prestressed spring 21 has two ends. The prestressed spring 45 is fastened at one of its ends to the component 42 and at its other end to the frame 22 and is biased such that it is able to pull the flap 21 into its first position by means of the component 42. The spring 45 may also be attached with one of its ends directly to the flap 21 and with its other end to the frame 22.

The bi-stable mechanism 41 further includes a guide 46. The guide 46 is connected at one of its ends to the frame 22. The other end of the guide 46 is designed as a pin 47 which runs in the heart-shaped contour 44. The heart-shaped contour 44 are associated with the two stable and the two unstable states.

As already mentioned, the component 42 pivots with the pivoting of the flap 21, so that the heart-shaped contour 44 is aligned differently depending on the position of the flap 21 and thus the pin 47 relative to the heart-shaped contour 44 depending on the position of the flap 21 at different Positions within the heart-shaped contour 44 is located. The heart-shaped contour 44 is designed such that it allows the closing of the flap 21 when the bi-stable mechanism 41 or the component 42 is in its first stable state. If the bi-stable mechanism 41 or the component 42 is in the second stable state, then likewise the spring 45 tries to pull the flap 21 into its first position. Due to the heart-shaped contour 44, however, prevents the pin 47, as in the Fig. 5c shown, a complete pivoting back of the device 42 and thus closing the flap 21 when cooled wire 24 of a shape memory alloy. Thus, the pin 42 holds the component 42 in its second stable state and thus the flap 21 in its second position, ie in its open position, even without heating or impinging the wire 24 from a shape memory alloy with electrical energy.

The FIGS. 5a-d illustrate the operation of the bi-stable mechanism 41. Closes the flap 21, the opening 8, it is in its first position in which the wire 24 is cooled from a shape memory alloy and thus pulled by means of the prestressed spring 45 in particular to its maximum length can be. In the bi-stable mechanism 41 is in its first stable state, whereby the pin 47 cooperates with the heart-shaped contour 44 of the component 42 in such a way that the flap 21 allows the opening 8 to be closed or the flap 21 allowed, 45 take their first position by means of the prestressed spring.

If now the flap 21 are opened so that air can flow through the opening 8 from the freezer compartment 4 into the coolable interior 3, the wire 24 is heated from a shape memory alloy, in the case of the present embodiment, the control device 10 with the wire 24th power source connected to a shape memory alloy to turn on the wire 24 made of a shape memory alloy with electrical energy. As a result, the wire 24 is composed of a shape memory alloy and thereby pivots the flap 21 with respect to the pivot axis 21, whereby the flap 21 opens the opening 8. During pivoting of the flap 21 also pivots the device 42, whereby the pin 47 relative to the heart-shaped contour 44 as long as its position changes until the bi-stable mechanism in the Fig. 5b achieved first unstable state. In the first unstable state of the bi-stable mechanism 41, the flap 21 is opened slightly wider than in its second position. The flap 21 is thus pivoted beyond its second position.

When the flap 21 is pivoted so far that the bi-stable mechanism 41 has reached its first unstable state, the control device 10 turns off the power source again, causing the shape memory alloy wire 24 to cool and thereby re-engage by means of the biased spring 45 can be stretched to its original length. This allows the prestressed spring 45 to pivot the flap 21 again so that it tries to close the opening 8 again. Due to the heart-shaped contour 44, however, the pin 47 is guided into a position within the heart-shaped contour 44, in which the bi-stable mechanism 41 and the component 42 reaches its second stable state. This is in the Fig. 5c shown. In the second stable state, however, the pin 47 prevents the member 42 from pivoting back so far that the flap 21 closes the aperture 8, thereby holding the flap 21 in its second position without the need for the shape memory alloy wire 24 heat.

If the flap 21 is closed again, then the control device 10 switches on again the voltage source, whereby the wire 24 of a shape memory alloy contracts and thereby the flap 21 as long pivoting opens until the bi-stable mechanism in the Fig. 5d achieved second unstable state. Thereafter, the controller 10 turns off the power source again, thereby cooling the shape memory alloy wire 24 and thus being stretchable, thereby allowing the biased spring 45 to pivot the flap 21 so as to close the opening 8. Due to the heart-shaped contour 44, the pin 47 now allows pivoting of the component 42 such that the bi-stable mechanism 41 is able to assume its first stable state again, thereby also allowing the flap 21 to assume its first position around the opening 8 to close.

LIST OF REFERENCE NUMBERS

1

Household refrigerator

2

heat-insulated housing

3

coolable interior

4

freezer

5

partition wall

6

door leaf

7

door leaf

8th

opening

9

adjustment

10

control device

21

flap

22

frame

23

swivel axis

24

wire

25

fastening device

26

bag

27

opening

28

spring-loaded element

29

groove

41

bi-stable mechanism

42

module

43

surface

44

heart-shaped contour

45

preloaded spring

46

guide

47

pen

b

width

H

height

Claims (13)

1. Household appliance, especially a household refrigeration appliance (1), having a flap (21) disposed such that it is able to be pivoted in relation to a pivot axis (23) between at least two positions and an adjustment facility (9) which is configured to pivot the flap (21) back and forth between the at least two positions, and which has a shape memory alloy wire (24) coupled to the flap (21), which becomes shorter when heated up and through this action pivots the flap (21) from a first position into a second position, wherein the shape memory alloy wire (24) has two ends, with which the shape memory alloy wire (24) is attached at a distance from the pivot axis (23) to a fixed component (22) of the household appliance and the shape memory alloy wire (24) is also attached at a distance from the pivot axis (23) to the flap (21) by means of an attachment facility (25), characterised in that the attachment facility (25) has a pocket (26) disposed on the flap (21) with an opening (27) facing away from the pivot axis (23) and a spring-pretensioned element (28) guided within the pocket (26) to which the shape memory alloy wire (24) is attached, wherein the spring-pretensioned element (28) is pretensioned such that it pushes the shape memory alloy wire (24) away from the pivot axis (23).
2. Household appliance according to claim 1, characterised in that the adjustment facility (9) comprises an electrical energy source by means of which the shape memory alloy wire (24) is able to have electrical energy applied to it in order to be heated up.
3. Household appliance according to claim 1 or 2, characterised in that the connecting line between those positions at which the two ends of the shape memory alloy wire (24) are attached to the fixed component (22) of the household appliance runs in parallel to the pivot axis (23).
4. Household appliance according to one of claims 1 to 3, characterised in that, viewed from above, the shape memory alloy wire (24) is attached to the flap (21) between its ends by means of the attachment facility (25), especially centrally in relation to its ends, to the flap (21) by means of the attachment facility (25).
5. Household appliance according to claim 4, characterised in that the flap (21) extends along the pivot axis (23) by a width (b), and the length of the connecting line between those positions at which the ends of the shape memory alloy wire (24) are attached to the fixed component (22) of the household appliance, is greater than or equal to the width (b) of the flap (21), and the attachment facility (25) is especially disposed centrally in relation to the width (b) of the flap (21).
6. Household appliance according to one of claims 1 to 5, characterised in that the spring - pretensioned element (28) has a groove (29) which opens directed away from the pivot axis (23) and in which the shape memory alloy wire (24) is guided.
7. Household appliance according to one of claims 1 to 6, characterised by an opening (8) which is closed off with the flap (21) when the flap (21) is in its first position and which is opened when the flap (21) is in its second position.
8. Household appliance according to claim 7, characterised in that it is embodied as a household refrigeration appliance having at least two temperature zones of different temperature, wherein the opening (8) connects a first temperature zone (3) of the temperature zones to a second temperature zone (4) of the temperature zones, so that cooled air is capable of flowing between the first temperature zone (3) and the second temperature zone (3) when the flap (21) is in its second position.
9. Household appliance according to claim 7 or 8, characterised in that it is designed as a fridge freezer combination with a coolable inner compartment (3) and a freezer compartment (4), wherein the opening (8) connects the coolable inner compartment (3) to the freezer compartment (4) so that cooled air can flow from the freezer compartment (4) to the coolable inner compartment (3) when the flap (21) is in its second position.
10. Household appliance according to one of claims 1 to 9, characterised in that the adjustment facility (9) has a bistable mechanism (41) coupled to the flap (21) having a pretensioned spring (45) which is pretensioned such that it attempts to pivot the flap (21) into its first position, and which has a first stable state, a second stable state, a first unstable state and a second unstable state, wherein the first stable state is assigned to the first position and the second stable state to the second position of the flap (21), so that the bistable mechanism (41), in this first stable state, holds the flap (21) in its first position and in the second unstable state holds it in its second position, and the pretensioned spring (45) attempts, in the first unstable state, to move the bistable mechanism (41) into its second stable state and in the second unstable state into its first stable state.
11. Household appliance according to claim 10, characterised in that the bistable mechanism (41) comprises the following elements:

    - The pretensioned spring (45) which is pretensioned such that it attempts to pivot the flap (21) into its first position,

    - A component (42) with a surface (43) which is aligned at least approximately at right angles to the pivot axis (23) and in which a heart-shaped contour (44) running in the form of a groove is disposed, wherein the component (42) is part of the flap (21) or is rigidly connected to the latter and thus the component (42) and the heart-shaped contour (44) pivot together with the flap (21) and the heart-shaped contour (44) is assigned the two stable states and the two unstable states,

    - A pin (47) engaging in the heart-shaped contour (44), which interacts with the heart-shaped contour (44) such that the pin (47) holds the flap (21) in its first position, when the bistable mechanism (41) is in its first stable state, and holds the flap (21) in its second position when the bistable mechanism (41) is in its second stable state.
12. Method for operating a household appliance according to claim 10 or 11, having the following method steps:

    - Heating up the shape memory alloy wire (24) so that the latter becomes shorter and pivots the flap (21) against the spring force of the pretensioned spring (45) from its first position beyond the second position, so that the bistable mechanism (41) assumes its first unstable state, and

    - Letting the shape memory alloy wire (24) cool down so that the pretensioned spring (45) is capable of pivoting the flap (21) in the direction of the first position of the flap (21) until the bistable mechanism (41) reaches its second state and the flap (21) assumes its second position.
13. Method according to claim 12, additionally having the following method steps:

    - Heating up the shape memory alloy wire (24) so that the latter becomes shorter and pivots the flap (21) against the spring force of the pretensioned spring (45) from its second position beyond the second position, so that the bistable mechanism (41) assumes its second unstable state, and

    - Letting the shape memory alloy wire (24) cool down so that the pretensioned spring (45) is capable of pivoting the flap (21) in the direction of the first position of the flap (21) until the bistable mechanism (41) reaches its first state and the flap (21) assumes its first position.

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