Actuator system comprising a braking unit

Abstract

The invention relates to an actuator system (1) comprising a first actuating element (2.1, 2.2) and a second actuating element (3.1, 3.2), wherein the actuating elements (2.1, 2.2, 3.1, 3.2) are produced from a shape memory alloy and can each be supplied individually with electric energy so as to perform a length contraction, and the actuating elements (2.1, 2.2, 3.1, 3.2) each have a first end which is mounted fixedly and a second end which is mounted so as to be movable translatably. The actuator system also comprises a slider (4) which is located between the second ends of the actuating elements (2.1, 2.2, 3.1, 3.2), wherein: the slider (4) is movable translatably in opposite actuating directions (S1, S2) due to the actuating elements (2.1, 2.2, 3.1, 3.2) being arranged in such a way that, when they perform a length contraction, tensile forces acting on the slider (4) are acting in opposite directions; and a braking unit (5, 6) is provided between the second ends of the actuating elements (2.1, 2.2, 3.1, 3.2), which braking unit (5, 6) is movable together with the slider (4) in the actuating directions (S1, S2) and is designed to brake an actuating movement of the actuator system (1) when the supply of electric energy to at least one of the actuating elements (2.1, 2.2, 3.1, 3.2) is interrupted.

Description

[0001] Actuator system with brake unit

[0002] The invention relates to an actuator system comprising a first actuating element and a second actuating element, wherein the actuating elements are made of a shape memory alloy and can each be individually supplied with electrical energy to execute a length contraction. The actuating elements each have a fixedly mounted first end and a translationally movable second end. A rotor is arranged between the movable second ends of the actuating elements, which is translationally adjustable in opposite actuating directions.

[0003] Actuator systems with actuators made of shape memory alloys (SMAs) are known. Shape memory alloys are capable of changing their shape depending on temperature. When heated to a temperature above a transformation temperature, the shape memory alloy undergoes a phase transformation, transforming from a more malleable cold phase (martensite) to a stiffer warm phase (austenite). An elongated actuator made of a shape memory alloy undergoes a length contraction when a tensile force is applied. The applied tensile force can be used in an actuator system as an actuating force, and the exerted length contraction is used to drive an actuating movement.

[0004] The thermal energy or heat required for the shape or phase transformation of the actuator can be provided by electrical energy. For this purpose, the actuator is subjected to an electrical current, whereby the actuator experiences a temperature increase due to its internal electrical resistance according to Joule's first law. The temperature increase correlates with the supplied electrical energy. When the electrical current flow is removed, the actuator generally cools down again by releasing heat to the environment. Without external tensile forces, the actuator retains its length-contracted shape, which it assumed during electrical heating above the transformation temperature.

[0005] Furthermore, actuator systems of the aforementioned type are known in which a return element, for example a return spring or another actuating element made of a shape memory alloy, is attached to an actuating element made of a shape memory alloy. The return element applies a return force that is smaller than the tensile force exerted by the actuating element during length contraction and causes the actuating element to return to its original (length-relaxed) shape prior to the length contraction upon cooling below the transformation temperature. This temperature-induced change in the shape of the actuating element is repeatable and can therefore be used in actuator systems for reversible actuating movements.The use of an additional actuating element made of a shape memory alloy as a return element in the actuator system also enables a reciprocal actuating movement, i.e., a movement that can be carried out in two opposing actuating directions. The actuating elements can be energized alternately or individually and are arranged in opposite directions with respect to the tensile forces generated during the length contraction, allowing an actuating movement to be carried out either in a first actuating direction or in an opposite second actuating direction.

[0006] In order for these known actuator systems to move to and maintain a defined position, the actuator must be continuously supplied with sufficient electrical current or heat to execute or maintain its length contraction. If the electrical current is interrupted or removed, the actuator cools rapidly due to heat transfer to the environment and is retracted to its original, extended shape by the opposing actuator or return element. However, this continuous current supply to the actuators, which is required to move to and maintain a defined position, leads not only to increased power consumption but also to high stress and thus a reduced service life of the actuators.

[0007] The object of the present invention is to provide an improved actuator system with adjusting elements made of a shape memory alloy.

[0008] To achieve this objective, the invention comprises the features of patent claim 1. Accordingly, the rotor of the actuator system according to the invention is translationally adjustable in opposite adjustment directions by arranging the adjustment elements such that, upon their length contraction, the tensile forces acting on the rotor are directed in opposite directions. Furthermore, the actuator system comprises a braking unit arranged between the second ends of the adjustment elements and movable with the rotor along the adjustment directions. The braking unit is designed to brake or block an adjustment movement of the actuator system in the event of an interruption of the electrical power in at least one of the adjustment elements.

[0009] The particular advantage of the invention is that the actuator system can execute a reciprocal translational actuating movement in opposite actuating directions with a defined actuating force (tensile force) and with a defined actuating stroke within a defined actuating range. The rotor can therefore move to any actuating position within the actuating range and be held or remain at these actuating positions. The braking unit is advantageously designed to be self-braking in the event of a power interruption or removal, for example in the event of a power failure. This prevents an unintentional resetting of the rotor due to cooling of the previously energized, length-contracting actuating element. In this respect, a defined actuating position of the rotor can be moved to and held without the need for continuous energization of the actuating element.The actuator system according to the invention therefore operates more energy-efficiently and saves energy. Depending on the dimensioning and coordination of its components, the brake unit can slow down the actuating movement, similar to a friction clutch, or even completely block it.

[0010] According to a preferred embodiment of the invention, the brake unit has at least one pivotable brake lever which can be moved from a release position into a braking position and back and which, in the braking position, is pressed against a friction surface by applying a braking force.

[0011] The friction surface is preferably provided by a housing. The other components of the actuator system can be accommodated in the housing. The housing can be designed as a component of the actuator system according to the invention.

[0012] According to a further development of the invention, the brake unit has a force source, preferably a preload spring, applied to the brake lever for applying the braking force. A preload spring represents a particularly simple and cost-effective force source with a defined spring characteristic, which can hold the brake lever in the braking position autonomously, i.e., without an external control signal or auxiliary energy.

[0013] According to a further development of the invention, the brake unit comprises at least one electrically conductive brake actuator made of a shape memory alloy. The brake actuator can be subjected to electrical energy to execute a longitudinal contraction that counteracts the force source and moves the brake lever into the release position. When energized, the brake actuator, analogous to the actuators, executes a longitudinal contraction by applying a tensile force that is greater than the compressive force of the force source and counteracts this compressive force.

[0014] According to a further development of the invention, the brake unit has two brake actuating elements arranged in parallel and electrically connected in series. This arrangement enables the application of a high braking force in a small space, allowing the brake unit to be designed compactly. Furthermore, the brake actuating elements can thus be easily used as current conductors. Preferably, the brake unit has two brake levers that can be pivoted synchronously in a pincer-like manner or in opposite directions. Preferably, a first brake actuating element is assigned to a first brake lever, and a second brake actuating element is assigned to a second brake lever.

[0015] According to a further development of the invention, the brake actuator is electrically connected to the first actuator or the second actuator. Consequently, the actuating movement can be released or the braking function of the brake unit can be canceled directly via the electrical operating current of the actuators. The operating current of the actuators therefore autonomously provides both an enable signal for canceling the braking effect and the electrical energy required for this, if required. This advantageously eliminates the need for additional electrical signal lines and power lines for the brake unit, significantly simplifying the design and adjustability of the actuator system.

[0016] According to a further development of the invention, a temperature limit switch is connected to the brake actuator. The temperature limit switch is designed to interrupt the power supply to the brake actuators when a critical temperature limit is exceeded, allowing the brake actuators to cool down. This protects the brake actuators from critical overheating.

[0017] According to a further development of the invention, the brake actuator is connected to a specific electrical resistance or resistor. Preferably, the brake actuators of the brake unit are connected in parallel to the resistor (voltage divider circuit). This allows the brake actuators to be operated with a defined second supply voltage that differs from the first supply voltage of the actuators, advantageously eliminating the need for a complicated logic circuit or the like.

[0018] According to a further development of the invention, the second ends of the adjusting elements are connected to one another via at least one force transmission means, preferably a wire rope. A wire rope represents a simple and cost-effective embodiment for the force transmission means.

[0019] Preferably, the at least one force transmission means is deflected via deflection pulleys. The force flow between the first actuating element and the second actuating element and the actuating movement of the rotor can thus be guided and deflected in a defined manner in a simple and versatile manner, whereby defined translational actuating movements can be specified, in particular linear, but also arcuate or curved actuating movements.

[0020] The rotor is preferably held on the at least one force transmission means or between a first force transmission means and a second force transmission means.

[0021] According to a further development of the invention, the actuator system according to the invention comprises two brake units, wherein a first brake unit is assigned to the first actuating element and a second brake unit is assigned to the second actuating element. The brake units are preferably of the same type or have the same effect and are connected to one another via the at least one force transmission means.

[0022] Preferably, the brake units are electrically connected to one another. The brake actuators can be connected to the first actuators and second actuators in such a way that the braking effect of both brake units is activated simultaneously upon loss or interruption of the current flow in the first actuators or in the second actuators or in all actuators.

[0023] According to a further development of the invention, the adjusting elements or the at least one brake adjusting element are formed from an elongated wire. This wire-shaped design enables particularly simple and cost-effective production of the adjusting elements or the brake adjusting element.

[0024] The adjusting elements are preferably formed from a spirally wound wire. The adjusting elements form a spiral spring, allowing predetermined spring characteristics to be developed for the adjusting elements. Furthermore, the adjusting elements in the form of a spirally wound wire have a large surface area for heat transfer in a small space. This allows the adjusting elements to be advantageously designed with a reduced cross-section or wire diameter, since less thermal radiation is required than with a thick wire with a large diameter.

[0025] According to a further development of the invention, the actuator system comprises two first actuating elements and two second actuating elements arranged in parallel and electrically connected in series. This parallel arrangement of the actuating elements advantageously allows for a greater tensile force to be applied with a constant actuating stroke, allowing the actuator system to be designed with a more compact size in terms of its longitudinal extension. Furthermore, the parallel arrangement of the actuating elements enables simple electrical connection to the brake unit, with one of the actuating elements serving as a supply conductor and the other as a collector for the electrical current.

[0026] The shape memory alloy of the actuating elements or of the at least one brake actuating element is preferably a nickel-titanium alloy. These shape memory alloys based on the alloying elements nickel and titanium exhibit good corrosion resistance as well as high tensile strength and elongation at break. The alloy compositions of the actuating elements are selected in particular depending on the expected ambient or operating temperatures and can therefore also be designed as ternary shape memory alloys, such as NiTiCu, NiTiFe, NiTiHf, NiTiZr, NiTiNb, NiTiCr, NiTiV, or as higher-alloyed, for example, quaternary shape memory alloys.

[0027] The precise composition of the shape memory alloy is preferably matched to the intended environment or application situation in terms of material technology. The alloy composition is preferably selected so that the transformation temperature of the shape memory alloy is higher than the expected maximum ambient temperature. This prevents unwanted longitudinal contraction of the adjusting elements at high ambient temperatures. Further advantages, features, and details of the invention can be found in the further subclaims and the following description. The features mentioned therein may be essential to the invention individually or in any combination. The drawings serve merely as examples to clarify the invention and are not limiting in nature.

[0028] They show:

[0029] Fig. 1 is a schematic plan view of an actuator system according to the invention with a rotor in a basic / central position,

[0030] Fig. 2 is a schematic plan view of the actuator system according to the invention shown in Fig. 1, wherein the rotor has been moved from the basic / central position along a first adjustment direction,

[0031] Fig. 3 is a schematic plan view of the actuator system according to the invention according to Fig. 1, wherein the rotor has moved along the first adjustment direction to a first end position,

[0032] Fig. 4 is a schematic plan view of the actuator system according to the invention according to Fig. 1, wherein the rotor is moved along a second adjustment direction to a second end position,

[0033] Fig. 5 is a plan view of a second brake unit of the actuator system according to the invention according to Fig. 1 with brake levers in a release position,

[0034] Fig. 6 is a plan view of the second brake unit of the actuator system according to the invention according to Fig. 1 with the brake lever in a braking position,

[0035] Fig. 7 is a plan view of the second brake unit of the actuator system according to the invention shown in Fig. 1 with an activated temperature limit switch and the brake levers in the braking position, Fig. 8 is a side view of the second brake unit of the actuator system according to the invention shown in Fig. 1 with the brake levers in the braking position,

[0036] Fig. 9 is a perspective rear view of the second brake unit of the actuator system according to the invention according to Fig. 1 with the brake levers in the braking position and

[0037] Fig. 10 is a perspective front view of the second brake unit of the actuator system according to the invention shown in Fig. 1 with the brake levers in the braking position.

[0038] A first embodiment of an actuator system 1 according to the invention, which is designed to carry out a reciprocal, linear actuating movement in opposing actuating directions S1, S2, is shown in the following Fig. 1 to Fig. 10.

[0039] The actuator system 1 comprises two first actuating elements 2.1, 2.2, which are of equal length and arranged parallel to one another, and two second actuating elements 3.1, 3.2, which are of equal length and arranged parallel to one another. The first actuating elements 2.1, 2.2 and the second actuating elements 3.1, 3.2 are each made of a shape memory alloy (SMA), whereby the actuating elements 2.1, 2.2, 3.1, 3.2 contract in length when heated to a temperature above a transformation temperature of the shape memory alloy. This transformation temperature can vary depending on the material or can be predetermined. According to the present invention, the thermal energy or heat required for this purpose is provided by electrical energy, i.e. the actuating elements 2.1, 2.2, 3.1, 3.2 are electrically conductive and electrically contacted with an electrical current source, such that the actuating elements 2.1, 2.2, 3.1, 3.2 can be heated to a temperature above the transformation temperature of the shape memory alloy when subjected to electrical energy. The degree of length contraction of the actuating elements 2.1, 2.2, 3.1, 3.2 can be controlled by supplying electrical energy, which correlates with the temperature increase according to Joule's first law. This allows the rotor 4 to be moved to defined positions within the actuating range. The first actuating elements 2.1, 2.2 and the second actuating elements 3.1, 3.2 are arranged in opposite directions to one another such that tensile forces caused by a length contraction of the actuating elements 2.1, 2.2, 3.1, 3.2 are directed in opposite directions. A first tensile force, which is applied by the first actuating elements 2.1, 2.2, is oriented along a first actuating direction S1. A second tensile force, which is generated by the second adjusting elements 3.1, 3.2 is applied, is oriented along an opposite second adjustment direction S2.

[0040] The adjusting elements 2.1, 2.2, 3.1, and 3.2 are each designed as a spiral spring or a spirally wound SMA wire. As a result, the adjusting elements 2.1, 2.2, 3.1, and 3.2 exhibit a tensile force, even at temperatures below the transformation temperature of the shape memory alloy, that is smaller than the tensile force during their length contraction in the heated state.

[0041] The first actuating elements 2.1, 2.2 and the second actuating elements 3.1, 3.2 are each firmly clamped at their outer first ends or fixed by a fixed bearing 22, which also serves to supply electrical current. Opposite second ends of the actuating elements 2.1, 2.2, 3.1, 3.2 are mounted for linear movement in the two actuating directions S1, S2 and are connected and electrically contacted to a braking unit 5, 6.

[0042] A first brake unit 5 is assigned to the first actuating elements 2.1, 2.2, and a second brake unit 6 designed analogously to the first brake unit 5 is assigned to the second actuating elements 3.1, 3.2.

[0043] The brake units 5, 6 are designed to brake or block an actuating movement of the actuator system 1 as soon as the actuating element 2.1, 2.2, 3.1, 3.2 assigned to them is de-energized. The braking function of the brake units 5, 6 is canceled, thus enabling an actuating movement as soon as the actuating elements 2.1, 2.2, 3.1, 3.2 assigned to them are sufficiently energized.

[0044] The brake units 5, 6 are connected to each other via two wire cables serving as force transmission means 8.1, 8.2. A slider 4 is held between the force transmission means 8.1, 8.2, each of which is linearly displaceable in the opposite adjustment directions S1, S2. The slider 4 thus forms a movable element of the actuator system 1 according to the invention, similar to a carriage of a linear guide. External components to be adjusted by the actuator system 1 according to the invention can be connected to the slider 4.

[0045] In Fig. 1, the rotor 4, or the actuator system 1 according to the invention, is in a basic position or central position. The rotor 4 is at the same distance from the first ends of the first actuating elements 2.1, 2.2 and the second actuating elements 2.2. The first actuating elements 2.1, 2.2 and the second actuating elements 3.1, 3.2 are de-energized here and have a temperature below the transformation temperature of the shape memory alloy, so that the actuating elements 2.1, 2.2, 3.1, 3.2 have a length-relaxed basic shape.

[0046] Fig. 2 shows the actuator system 1 according to the invention with the rotor 4 figuratively shifted to the left along the first actuating direction S1 compared to the basic or central position. This actuating movement is caused by a length contraction of the two second actuating elements 3.1, 3.2. For this purpose, the second actuating elements 3.1, 3.2 have been subjected to electrical current and have consequently contracted or performed a length contraction under the application of a second tensile force. This second tensile force of the length-contracted second actuating elements 3.1, 3.2 is greater in the heated, length-contracted state than in the cold, length-relaxed state. In response to the length contraction of the actuating elements 3.1, 3.2, the non-energized first actuating elements 2.1, 2.2, which are non-positively connected to them, have been stretched or pulled apart accordingly.

[0047] In Fig. 3, the two second actuating elements 3.1, 3.2 are completely contracted in length, i.e. maximally contracted, whereby the first actuating elements 2.1, 2.2 are accordingly further stretched or compressed compared to the state according to Fig. 2 and the rotor 4 is moved further to the first end position or stop position along the first actuating direction S1.

[0048] An adjusting movement of the rotor 4 along the second adjusting direction S2, which is opposite to the first adjusting direction S1 and figuratively points to the right, is shown in Fig. 4. This adjusting movement occurs in reverse by applying electrical energy to the two first adjusting elements 2.1, 2.2 and heating them to a temperature above the transformation temperature of the shape memory alloy. The first adjusting elements 2.1, 2.2 thereby perform a length contraction by applying a first tensile force. The second adjusting elements 3.1, 3.2 are thereby stretched or pulled apart accordingly, and the rotor 4 is moved along the second adjusting direction S2, which figuratively points to the right, to a second end position or stop position.

[0049] The force transmission means 8.1, 8.2 are guided by a total of four deflection pulleys 7.1, 7.2, 7.3, 7.4, each arranged in pairs, and are deflected by two 180° turns, so that the actuator system 1 according to the invention has an S-shape. The end positions or stop positions of the rotor 4 are arranged between the deflection pulleys 7.1, 7.2, 7.3, 7.4, so that the rotor 4 executes a purely linear actuating movement. The brake units 5, 6 are always arranged at the same height relative to one another.

[0050] A detailed plan view of the second brake unit 6 of the actuator system 1 according to the invention is shown in Figs. 5 to 7. The second brake unit 6 is shown here as representative of the two identically designed brake units 5, 6.

[0051] The second brake unit 6 comprises a base plate 9, with a flat or planar plate underside 21 and with a sliding wing 17. The base plate 9 serves as a type of frame or chassis for the second brake unit 6. The flat plate underside 21 and the sliding wing 17 of the base plate 9 enable the second brake unit 6 to be moved along the adjustment directions S1, S2 when accommodated in a housing, a guide rail or the like (not shown in the figure).

[0052] The second actuating elements 3.1, 3.2 are fixed to the base plate 9 via screw-shaped connecting means 19.1, 19.2 and are electrically connected thereto. Thus, electrical current can flow from one of the two second actuating elements 3.1, 3.2 into the second brake unit 6 and out of the second brake unit 6 via the other of the two second actuating elements 3.1, 3.2.

[0053] The second brake unit 6 has two brake actuating elements 10.1, 10.2, which are also made of a shape memory alloy and which are each oriented parallel to one another and are designed as a single elongated wire.

[0054] The brake actuators 10.1, 10.2 are electrically connected to the second actuators 3.1, 3.2. Advantageously, the brake actuators 10.1, 10.2 can be activated to execute a length contraction by the electrical current that also flows through the second actuators 3.1, 3.2. The second brake unit 6 can therefore be operated without an additional electrical signal line or an additional electrical power supply line.

[0055] The brake actuators 10.1, 10.2 are connected in parallel with a resistor 14, or specific electrical resistance. The resistor 14 is preferably connected in parallel with the brake actuators 10.1, 10.2 in order to be able to apply a lower supply voltage to the brake actuators 10.1, 10.2 than to the second actuators 3.1, 3.2.

[0056] The brake actuating elements 10.1, 10.2 are each of equal length and are firmly clamped at a first end and connected at a second end to one of the pivotably held brake levers 11.1, 11.2. The brake levers 11.1, 11.2 are connected to one another in a pincer-like manner via an articulated cable 13 and are each preloaded by a preload spring 12.1, 12.2 assigned to them. This preload causes the brake levers 12.1, 12.2 to be pressed against an external friction surface 15 with a braking force when the second brake unit 6 is not activated. In this respect, the second brake unit 6 brakes or blocks the actuating movement of the second actuating elements 3.1, 3.2 along the actuating directions S1, S2 independently or autonomously in a non-activated state.

[0057] The braking function of the second brake unit 6 is only released when electrical current is applied, which is passed through the second actuating elements 3.1, 3.2. This occurs when the brake actuating elements 10.1, 10.2 are heated to a temperature above the transformation temperature of the shape memory alloy by applying electrical energy or electrical current. The electrically coupled brake actuating elements 10.1, 10.2 then contract in length, which causes the brake levers 11.1, 11.2 to be pivoted from the braking position (Fig. 6) into a release position (Fig. 5), in which the brake levers 11.1, 11.2 are held at a distance from the friction surfaces 15. An actuating movement of the second brake unit 6 along the first actuating direction S1 or the second actuating direction S2 is then possible without braking.

[0058] The friction surface 15 is preferably provided by a housing in which the other components of the actuator system 1 according to the invention are accommodated. The housing is not shown in the figure. Preferably, the fixed bearings 22 for the actuating elements 2.1, 2.2, 3.1, 3.2 are also formed as part of this housing. The second brake unit 6 is connected to the second force transmission means 8.2 by folding a tab of the second force transmission means 8.2 around a connecting eyelet 16 of the second brake unit 6.

[0059] To protect the components, particularly the brake actuators 10.1, 10.2, from overheating, the second brake unit 6 includes a temperature limit switch 18 that intervenes when a defined critical temperature limit is exceeded. The intervention of the temperature limit switch 18 is shown in Fig. 7 and results in the brake actuators 10.1, 10.2 being de-energized in time before overheating occurs, allowing them to cool down and thus return from their length-contracted state to their original shape.

[0060] The invention is in no way limited to the embodiment of the actuator system 1 according to the invention shown in the figure. In particular, the components of the actuator system 1 according to the invention can be freely selected within wide limits with regard to their shape, dimensions, number, material selection, and arrangement relative to one another.

[0061] According to an alternative embodiment, the actuator system 1 comprises a plurality of runners 4 held on or between the force transmission means 8.1, 8.2. This embodiment can be used, for example, to adjust a plurality of sun protection slats, each of which is attached to the runner 4.

[0062] Identical components and component functions are identified by the same reference symbols.

Claims

Patent claims 1. Actuator system (1) comprising a first actuating element (2.1, 2.2) and a second actuating element (3.1, 3.2), wherein the actuating elements (2.1, 2.2, 3.1, 3.2) are made of a shape memory alloy and can each be individually supplied with electrical energy to perform a length contraction, wherein the actuating elements (2.1, 2.2, 3.1, 3.2) each have a fixed first end and a translationally movable second end, further comprising a runner (4) arranged between the second ends of the actuating elements (2.1, 2.2, 3.1, 3.2), wherein the runner (4) is translationally adjustable in opposite actuating directions (S1, S2) by arranging the actuating elements (2.1, 2.2, 3.1, 3.2) such that during their length contraction, force is applied to the runner. (4) acting tensile forces are directed in opposite directions, with further tension between the second ends of the actuating elements (2.1, 2.2, 3.1, 3.2) a brake unit (5, 6) which is movable with the runner (4) along the positioning directions (S1 , S2) and the brake unit (5, 6) is designed to brake a positioning movement of the actuator system (1) in the event of an interruption of the electrical energy in at least one of the positioning elements (2.1, 2.2, 3.1, 3.2).

2. Actuator system (1) according to claim 1, characterized in that the brake unit (5, 6) has at least one pivotable brake lever (11.1, 11.2), wherein the brake lever (11.1, 11.2) can be moved from a release position to a braking position and back, and wherein the brake lever (11.1, 11.2) is pressed against a friction surface (15) in the braking position by applying a braking force.

3. Actuator system (1) according to claim 2, characterized in that the friction surface (15) is provided by a housing.

4. Actuator system (1) according to claim 2 or 3, characterized in that the brake unit (5, 6) for applying the braking force connects to the brake lever (11.1, 11.2) an applied force medium, preferably a preload spring (12.1, 12.2). Actuator system (1) according to claim 4, characterized in that the brake unit (5, 6) has at least one electrically conductive brake actuating element (10.1, 10.2) made of a shape memory alloy, wherein the brake actuating element (10.1, 10.2) can be electrically energized to perform a length contraction that counteracts the force medium and moves the brake lever (11.1, 11.2) into the release position. Actuator system (1) according to claim 5, characterized in that the brake actuating element (10.1, 10.2) is electrically contacted with the first actuating element (2.1, 2.2) and / or second actuating element (3.1, 3.2). Actuator system (1) according to claim 5 or 6, characterized in that the brake actuating element (10.1, 10.2) is connected to a specific resistor (14). Actuator system (1) according to any one of claims 5 to 7, characterized in that a temperature overrun limit switch (18) is connected to the brake actuating element (10.1, 10.2). Actuator system (1) according to any one of claims 1 to 8, characterized in that the second ends of the actuating elements (2.1, 2.2, 3.1, 3.2) are connected to the brake actuating element (10.1, 10.2).2) are connected to each other via at least one power transmission means (8.1, 8.2), preferably a wire rope. Actuator system (1) according to claim 9, characterized in that the at least one power transmission means (8.1, 8.2) is deflected via pulleys (7.1, 7.2, 7.3, 7.4). Actuator system (1) according to claim 9 or 10, characterized in that the runner (4) is held on the at least one power transmission means (8.1, 8.2) and / or between a first power transmission means (8.1) and a second power transmission means (8.2). Actuator system (1) according to any one of claims 1 to 11, characterized in that it comprises two brake units (5, 6), wherein a first brake unit (5) is assigned to the first actuating element (2.1, 2.2) and a second brake unit (6) is assigned to the second actuating element (3.1, 3.2). Actuator system (1) according to claim 12, characterized in that the brake units (5, 6) are electrically contacted with each other. Actuator system (1) according to any one of claims 1 to 13, characterized in that the actuating elements (2.1, 2.2, 3.1, 3.2) and / or the at least one brake actuating element (10.1, 10.2) are formed from a wire and / or the actuating elements (2.1, 2.2, 3.1, 3.2) are formed from a spirally wound wire. Actuator system (1) according to one of claims 1 to 14, characterized in that two first actuating elements (2.1, 2.2) and second actuating elements (3.1, 3.2) are arranged in parallel and electrically connected in series with each other.2) are included and / or that the brake unit (5, 6) has two brake actuating elements (10.1 , 10.2) arranged in parallel and electrically connected in series, made of a shape memory alloy.

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