Device for actuating an actuator in a vehicle

Abstract

Device for actuating an actuating element (3) in a vehicle, comprising two actuator mechanisms (8, 17), each of which is formed from a shape memory alloy which undergoes a structural transformation when current is supplied, wherein the first actuator mechanism (8) acts on the actuating element (3) and is connected to an electrical circuit (23) for supplying current to the first actuator mechanism (8) for adjusting the actuating element (3), and consists of several actuator elements (19a, 19b, 19c; 21a, 21b, 21c) connected in series, wherein the actuator elements (19a, 19b, 19c;21a, 21b, 21c) are connected by connecting elements (20, 22) and can be energized independently of each other, and wherein the second actuator mechanism (17), connected to a further circuit (24), is coupled to a brake (11) for releasing the actuating element (3) by locking the actuating element (3) in the adjusted position, characterized in that the actuator elements (19a, 19b, 19c, 21) of the first actuator mechanism (8) consist of different shape memory alloys.

Description

The invention relates to a device for actuating an actuator in a vehicle, comprising two actuator mechanisms, each of which is formed from a shape memory alloy which undergoes a structural transformation when current is supplied, wherein the first actuator mechanism engages the actuator and is connected to an electrical circuit for supplying current to the first actuator mechanism for adjusting the actuator. From DE 10 2010 024 705 A1, an active flap vent using a shape memory alloy is known, which has a plurality of openings in a housing, each containing a flap. An actuator mechanism moves the flaps between an open and a closed position using a shape memory element. This is due to the material behavior of shape memory alloys, which can assume two different crystal structures. The crystal structure changes from martensite to austenite upon the application of heat at specific temperatures. This allows for large elastic strains. DE 10 2015 006 275 A1 discloses an air intake device for a vehicle with a pivoting flap element and a pivoting device that actuates it. The pivoting device has at least two spring elements, each made of a shape-memory alloy. The two spring elements are connected to the pivoting device in such a way that the pivoting device can be pivoted in one direction by heating one of the two spring elements and in the opposite direction by heating the other spring element. The pivoting device is thus limited to setting only two positions. The forces occurring in the air duct can cause the pivoting device to oscillate around its position. German patent application DE 10 2018 131 229 A1 discloses a device for actuating a louver in an automobile interior. The device comprises a first and a second shape memory element. The second shape memory element engages the louver and serves to adjust it. The first shape memory element is coupled to a brake element, which serves to release the louver. From DE 42 09 815 A1, an actuating device is known in which several memory metal wires can be connected in series to achieve an addition of the change in position. DE 600 31 687 T2 describes the control of actuators made of shape memory alloy using pulse width modulation (PWM). The object of the invention is to provide a device for actuating an actuator in a vehicle, by means of which an actuator remains stable in a multitude of its positions even when an external force is applied. The invention is defined by the features of the independent claims. Advantageous further developments and embodiments are the subject of the dependent claims. Further features, applications, and advantages of the invention will become apparent from the following description and the explanation of exemplary embodiments of the invention illustrated in the figures. The problem is solved by the subject matter of claim 1.In the device described above for actuating an actuating element (3) in a vehicle, comprising two actuator mechanisms (8, 17), each formed from a shape memory alloy that undergoes a structural transformation upon application of current, wherein the first actuator mechanism (8) acts on the actuating element (3), is connected to an electrical circuit (23) for energizing it, and consists of several actuator elements (19a, 19b, 19c; 21a, 21b, 21c) connected in series, wherein the actuator elements are connected by connecting elements (20, 22) and can be energized independently of one another, and wherein the second actuator mechanism (17), connected to a further electrical circuit (24), is coupled to a brake (11) for releasing the actuating element (3) by locking it in the adjusted position, the actuator elements (19a, 19b, 19c, 21) of the first actuator mechanism (8) according to the invention made of different shape memory alloys. In the device described above for actuating a positioning element in a vehicle, comprising two actuator mechanisms, each made of a shape-memory alloy that undergoes a structural transformation upon application of current, wherein the first actuator mechanism engages the positioning element and is connected to an electrical circuit for energizing the first actuator mechanism to adjust the positioning element, the second actuator mechanism, connected to a further electrical circuit, is coupled to a brake that locks the positioning element in the adjusted position and releases it. This allows for a multitude of stable positions of the positioning element to be set, resulting in cost and space reductions. Each of the set positions is secured by the brake.In particular, the use of actuator elements made of different shape memory alloys in a cascaded arrangement and their combinational control, as described in the invention, further increases the variety of adjustable positions. Such a device is particularly advantageous in series production applications in the automotive industry. In one embodiment, a spring element is attached to the brake to lock the actuator in its adjusted position. After the current flow to the second actuator mechanism is interrupted, the pre-tensioned spring element presses the brake against the actuator, thereby locking it in its current position. In a further embodiment, the first actuator mechanism is guided to the actuating element via at least one deflection pulley for extension. Extending the first actuator mechanism increases the resulting extension or contraction forces. The use of one or more deflection pulleys allows for space-saving guidance of the first actuator mechanism within the designated installation space of the vehicle. In a further embodiment, the first actuator mechanism consists of several actuator elements connected in series, with the actuator elements being linked by connecting elements and independently energized. Such cascading or series connection of the actuator elements of the first actuator mechanism allows intermediate positions to be easily set on the actuating element. To set these intermediate positions, the actuator elements of the first actuator mechanism can be energized individually or in any combination, resulting in different contraction forces and thus different positions of the actuating element. In a further embodiment, the actuator elements of the first actuator mechanism consist of different shape-memory alloys. This leads to different contractions of the various actuator elements, thereby increasing the range of possible positions of the actuating element. In a further embodiment, the first actuator mechanism or its actuator elements are designed as an energizable wire or an energizable spring unit. A multi-part actuator mechanism can be designed by forming each section of the actuator mechanism from a separate energizable wire or energizable spring element, whereby the separate wires can have different lengths, so that the contraction in each wire can be of a different magnitude. The use of multiple spring elements reduces the overall length. Furthermore, the deflection pulleys can be omitted, thus saving installation space. In a further embodiment, the circuit supplying the first actuator mechanism includes a control system for varying the current supply. This allows the contraction behavior of the first actuator mechanism to be influenced by the current supplied, enabling a refinement of the adjustment of various positions of the actuating element in addition to the design and material properties. In another embodiment, the circuit is designed to output a PWM signal. Such a PWM signal (pulse-width modulated signal) can be adjusted particularly easily by a control system, which further reduces costs. In a further embodiment, the actuating element is mounted on a rotatably supported axis, to which the first actuator mechanism engages. Such an arrangement ensures a reliable transmission of the contraction performed by the energized first actuator mechanism to the movement of the actuating element. In a further embodiment, a first gear is mounted on the axle, into which a second gear engages, with which the first actuator mechanism is coupled, the first and second gears establishing a gear ratio. This gear ratio can be determined by the size of the two gears, which in turn determines the actual force acting on the axle of the actuating element. Further advantages, features, and details will become apparent from the following description, in which at least one embodiment is described in detail. The described features can, individually or in any meaningful combination, constitute the subject matter of the invention, optionally also independently of the claims, and can, in particular, also be the subject matter of one or more separate applications. Figure 1 shows an embodiment of the device according to the invention in a first position of the actuating element, Figure 2 shows the embodiment of the device according to the invention according to Figure 1 in a second position of the actuating element, Figure 3 shows a further embodiment of the device according to the invention, Figure 4 shows a further embodiment of the device according to the invention. Figures 1 and 2 show a first embodiment of the device 1 according to the invention, which is arranged in a housing wall 2 of an air duct 18 of a vehicle's air conditioning system, through which a fluid, such as air, flows. The duct 18 has a fluid inlet 15 and a fluid outlet 16. The device 1 serves to adjust the position of an air flap 3, designed as an actuating element, which is arranged in the duct 18 and is rigidly coupled to a pivot shaft 4. A first gear 5 is attached to the pivot shaft 4, into which a second gear 6 engages. At a first suspension point 7, one end of a wire 8 made of a shape-memory alloy is attached to the second gear 6. The wire 8 is guided over two deflection pulleys 9a, 9b to a further suspension point 10, where the other end of the wire 8 is rigidly fixed. Opposite the first gear 5, which is fixed on the axis of rotation 4, a brake 11 is arranged, which can engage positively with the first gear 5. On the side of the brake 11 facing away from the gear 5, a spring 12 is attached, which is locked at a further suspension point 13. In addition, another wire 17 made of a shape-memory alloy is stretched between the brake 11 and another wire suspension 14. The ends of the first wire 8 are connected to a first circuit 23, while the ends of the second wire 17 are connected to a second circuit 24. The flap 3 is adjusted by selectively energizing wire 8 via circuit 23. The brake 11 is also actuated by energizing wire 17 via circuit 24. When the first wire 8 is energized by the circuit 23, it heats up, and the wire alloy undergoes a structural transformation from martensite to austenite, causing the first wire 8 to contract. This rotates the second gear 6 clockwise. The engagement of the second gear 6 with the first gear 5 creates a gear ratio, causing the first gear 5 to rotate counterclockwise. Since the first gear 5 is fixed to the axis of rotation 4, the flap 3 is also moved counterclockwise and assumes the second position shown in Fig. 2. During this adjustment process, the brake 11 is retracted from the first gear 5 by means of the second wire 17, which also contracts when current is supplied by the second power source 24, thus allowing the adjustment process to proceed unimpeded.After the adjustment process is complete, circuit 24 is interrupted, causing the second wire 17 to expand as its temperature decreases. The brake 11 is then pressed against the pivot axis 4 of the flap 3 by the pre-tensioned spring 12, causing the brake 12 to re-engage with the gear 5 and thus lock the flap 3 into its set position. This set position cannot be altered by the forces exerted on the flap 3 by the incoming airflow. Subsequently, the current supply to the first wire 8 is also interrupted by opening circuit 23. To enable different intermediate positions of the flap 3, the current supply to the first wire 8 is metered so that the structural transformation from martensite to austenite only partially occurs, thus allowing for varying degrees of contraction of the first wire 8. Advantageously, the current supply is varied via a PWM signal. The second wire 17 and the spring 12 of the brake 11 can, as an alternative to the description above, be arranged on both sides of the brake 11 instead of on the same side. In this case, the spring 12 would close the brake 11 with a tensile force rather than a compressive force. Fig. 3 shows a further embodiment of the device 1 according to the invention, in which, instead of a long first wire 8, several wires 19a, 19b, 19c of different lengths are used, which are made of different shape-memory alloys and coupled to one another by connecting elements 20. By such a cascade or series connection, the intermediate positions of the flap 3 can be set by energizing only individual wires 19a, 19b, 19c through the circuit 25. In this case, the structural transformation in each of the wires 19a, 19b, 19c is complete, and yet each wire 19a, 19b, 19c undergoes a different contraction, thereby increasing the number of intermediate positions of the flap 3.With three wires 191, 19b, 19c present, there are a total of 7 positions for the flap 3: First position: only wire 19a is energized, second position: only wire 19b is energized, third position: only wire 19c is energized, fourth position: wires 19a and 19b are energized, fifth position: wires 19b and 19c are energized, sixth position: wires 19a and 19c are energized, seventh position: all wires 19a, 19b, 19c are energized. The current is supplied via a parallel connection in circuit 25. Figure 4 shows a further embodiment of the device according to the invention, in which the wires 19a, 19b, 19c are replaced by several springs 21 made of a shape-memory alloy, which are connected to each other via connecting elements 22. By using springs 21 of different lengths and / or different diameters, different contractions can again be achieved. The current is supplied by means of the parallel connection in circuit 26.

Claims

Device for actuating an actuating element (3) in a vehicle, comprising two actuator mechanisms (8, 17), each of which is formed from a shape memory alloy which undergoes a structural transformation when current is supplied, wherein the first actuator mechanism (8) acts on the actuating element (3) and is connected to an electrical circuit (23) for supplying current to the first actuator mechanism (8) for adjusting the actuating element (3), and consists of several actuator elements (19a, 19b, 19c; 21a, 21b, 21c) connected in series, wherein the actuator elements (19a, 19b, 19c;21a, 21b, 21c) are connected by connecting elements (20, 22) and can be energized independently of each other, and wherein the second actuator mechanism (17), connected to a further electrical circuit (24), is coupled to a brake (11) for releasing the actuating element (3) which locks the actuating element (3) in the adjusted position, characterized in that the actuator elements (19a, 19b, 19c, 21) of the first actuator mechanism (8) consist of different shape memory alloys. Device according to claim 1, characterized in that a spring element (12) for locking the actuating element (3) in the adjusted position by the brake (11) is attached to the brake (11). Device according to claim 1 or 2, characterized in that the first actuator mechanism (8) is guided to the actuating element (3) via at least one deflection roller (9a, 9b) for its extension. Device according to one of the preceding claims, characterized in that the first actuator mechanism or the actuator elements (19a, 19b, 19c, 21) are designed as an energizable wire (8) or an energizable spring unit (21). Device according to at least one of the preceding claims, characterized in that the circuit (23) supplying the first actuator mechanism (8) comprises a control for varying the current supply. Device according to claim 5, characterized in that the circuit (23) is configured to output a PWM signal. Device according to at least one of the preceding claims, characterized in that the actuating element (3) is attached to a rotatably mounted axis (4) on which the first actuator mechanism (8) acts. Device according to claim 7, characterized in that a first gear (5) is attached to the axis (4), into which a second gear (6) engages, with which the first actuator mechanism (8) is coupled, wherein the first and the second gear (5, 6) provide a transmission ratio.

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