High-lift system for an aircraft as well as aircraft

Abstract

High-lift system for an aircraft with at least one mechanically adjustable flap which can be actuated by means of at least one actuator (1), wherein the actuator (1) is driven by the torque of a central power control unit (PCU) of the high-lift system, and wherein the at least one actuator (1) has an integrated release clutch (5) which interrupts the load path when a permissible response torque is exceeded, characterized in that a reset means is provided to manually close the release clutch (5) after an overload situation without removing the actuator (1).

Description

[0001] The invention relates to a high-lift system for an aircraft having at least one mechanically adjustable flap which can be actuated by means of an actuator, wherein the actuator is driven or can be driven by the torque of a central drive unit of the high-lift system.

[0002] Such high-lift systems are part of an aircraft's wings. Extending the flap increases the size of the wing and optimizes the aircraft's lift. High-lift systems are typically activated during takeoff and landing.

[0003] Embodiments known from the prior art are disclosed, for example, in DE 10 2015 012 237 A1, DE 10 2004 055 740 A1, DE 1 575 735 A, GB 131 309 A or DE 10 2013 000 544 A1.

[0004] The flaps located on the leading or trailing edge of the wing can be operated by dedicated actuators. The actuators themselves can be designed as spindle or rotary drives, for example. The individual actuators can be driven by a central drive unit, whose output shaft is routed along the wing to the respective actuators.

[0005] An important aspect in the design of such high-lift systems is protection against overload, for example, mechanical jamming of the flap kinematics, and the associated damage to the components, especially the actuators. For safety reasons, either torque limiters or shear sleeves are used, especially in conjunction with so-called no-backs, brakes, or skew detection.

[0006] The disadvantage of using a torque limiter is that the drive train must absorb the full torque of the drive unit in the event of a blockage and must therefore be designed to be robust. The resulting increased weight is a significant disadvantage, particularly in the aviation sector. In addition, if the drive train breaks, an additional brake must be installed on each wing to prevent the part of the drive train that is free-running due to the break from being moved by the air load. This brake must also be designed to be robust, which in turn means more weight.

[0007] Alternatively, so-called shear sleeves are used in the leading edge of the wing. These shear sleeves shear off in the event of an overload, thus preventing damage to the actuators. If a shear sleeve breaks, it must be completely replaced, which entails higher repair costs and thus higher operating costs. Furthermore, shear sleeves only work reliably at higher torques; at lower torques, however, the dispersion of shear sleeves is too high. Furthermore, shear sleeves cannot be used in plug-in actuators, as replacing them would be very costly. The actuator would have to be removed and opened.

[0008] Therefore, an improved solution for overload protection of a high-lift system is being sought that can reliably protect the installed actuators in the event of an overload, for example due to mechanical jamming of the flaps or failure of the installed gearbox.

[0009] This object is achieved by a high-lift system according to the features of claim 1. Advantageous embodiments of the high-lift system are the subject of the dependent subclaims.

[0010] According to the invention, a generic high-lift system is further developed in such a way that a return means is provided in order to manually close the integrated release clutch after an overload situation without removing the actuator.

[0011] Spindle drives or other rotary drives are conceivable as actuators. In principle, any type of actuator with a suitable input shaft for actuating the actuator is conceivable. The integrated release clutch ensures that, in the event of an overload situation, the actuator's input shaft is disconnected from the downstream drive path without load, preventing any damage to the actuator. A release clutch has the advantage that, when the clutch is opened accordingly, the drive shaft can rotate freely, and the applied torque of the central drive unit does not have to be absorbed by the actuator structure.

[0012] Furthermore, an unlocking clutch has the advantage that it can be closed again without any repair work in order to put the high-lift system back into operation after an overload event.

[0013] It is particularly advantageous if the release clutch is bistable. This means that the clutch remains stable in the respective switching positions, i.e., the clutch remains open after an overload situation occurs, even if the overload torque is no longer present. Only a defined actuation, preferably manual actuation, of the clutch leads to clutch engagement.

[0014] Furthermore, it is particularly preferred if the clutch closure, i.e., the activation of the release clutch, is possible regardless of the rotational position of the actuator's input shaft. This significantly simplifies the commissioning and activation of the clutch after the mechanical fault in the flap kinematics has been rectified, since rotating the shaft to a predetermined position is not necessary.

[0015] The power transmission of the disengaging clutch is preferably achieved by means of balls located in corresponding pockets of the clutch's drive and / or driven gear. To disengage the clutch, the balls can be disengaged from the corresponding pockets, preferably in the radial direction or alternatively in the axial direction, so that there is no positive power transmission between the drive and driven gears.

[0016] With a corresponding design of the override clutch, the drive gear or driven gear is preferably star-shaped, which facilitates clutch engagement regardless of the rotational position of the drive or driven gear. A star-shaped design of the respective gear means that the walls between the ball pockets converge radially, ideally converging to a point. This enables the balls to engage the respective ball pockets for clutch engagement, regardless of the rotational position of the drive gear.

[0017] To hold the balls in the corresponding ball pockets of the drive or driven gear, a corresponding pressure element is provided against which the balls butt in the engaged position. Ideally, the pressure element is mounted so that it can be moved axially to release the release path of the balls in the radial or axial direction. The pressure element can be preloaded so that the balls have to press against the force of the preload to disengage and open the clutch. The level of preload therefore defines the permissible response torque of the actuator. In an overload situation, for example, the balls press radially against the pressure element and move it axially against the preload, which ultimately allows the balls to disengage outwards in the radial direction and opens the clutch.

[0018] In a particularly preferred embodiment of the invention, the pressure element is designed as a pressure sleeve whose inner radius tapers outward. The conical inner wall of the sleeve thus represents a stop surface for the balls over the entire circumference of the sleeve. Due to the conicity, an axial displacement of the pressure sleeve changes the radius in the area of ​​the balls, i.e., an axial displacement of the sleeve outward can release the release path of the balls in the radial direction.

[0019] It is particularly preferred if the end face of the pressure sleeve facing the balls is provided with a surface that is inclined backward relative to the radial axis. When the clutch is opened, the balls move radially outward along the end face of the pressure sleeve. Due to the inclined end face, the balls are pushed further radially outward in the disengaged state and are thus held in the open clutch position.

[0020] According to the embodiment of the invention, a return means is provided for clutch closure in order to manually close the clutch after an overload situation without removing the actuator.

[0021] The return means can preferably be designed as a return sleeve with a conically tapered inner radius. In the disengaged state, the balls, for example, strike against the inner wall of the return sleeve. Axial displacement of the return sleeve reduces its inner radius, forcing the balls through the inner wall back into the pockets of the drive and / or driven gear.

[0022] The reset means, preferably the reset sleeve, is preferably adjustable by at least two manually operable operating means, which must be actuated simultaneously to engage the clutch. The requirement for synchronous actuation prevents inadvertent clutch engagement. The operating means could conceivably be designed as preloaded reset buttons that can be manually pushed axially against the reset sleeve.

[0023] In a preferred embodiment, the high-lift system comprises at least one gear, in particular a reduction gear, between the adjustable flap and the release clutch. In this case, the release clutch is preferably mounted on the drive side of the gear housing.

[0024] Furthermore, it is particularly advantageous if the installed gearbox includes a backstop to prevent unintentional flap movement when the release clutch is released.

[0025] In addition to the high-lift system according to the invention, the present invention also relates to an aircraft with at least one high-lift system according to the invention. The aircraft is accordingly characterized by the same advantages and properties as already explained above with reference to the high-lift system. For this reason, a repetitive description is omitted.

[0026] Further advantages and features of the invention will be explained in more detail below using an exemplary embodiment shown in the figures. They show: Fig. 1: a sectional view in axial direction through the actuator of the high-lift system according to the invention; Fig. 2: Fig. 1 as a three-dimensional representation; Fig. 3: a sectional view along the section axis AA of the Fig. 1 including the detailed representations C, D with the release clutch closed; Fig. 4: the sectional view according to Fig. 3 with the release clutch open.

[0027] Fig. 1 shows the actuator of the high-lift system according to the invention in a longitudinal section, Fig. Figure 2 is a perspective sectional view in the axial direction. Schematically indicated is the reduction gear 12, which is driven by a central drive unit (PCU) via the input shaft 1. The gear output ultimately causes the mechanical flap movement of the wings of an aircraft. A wing is usually equipped with a plurality of flaps, each of which is controlled by at least one, preferably two actuators 1 according to Fig. 1. All or a majority of the installed actuators 1 are operated via the central drive unit.

[0028] On the drive side of the gearbox housing 12, there is an override clutch 5, which allows a complete interruption of the load path from the central drive unit to the flap. The drive torque is transferred from the drive shaft 1 via splines to the drive sleeve 9, which is provided with ball-receiving pockets 13. Fig. 3 and Fig. 4 show sectional views along the section axis AA of the Fig. 1. Fig. 3 shows the release clutch 5 in the closed state, while Fig. 4 shows the opened clutch 5 for load path interruption. In addition, both Fig. 3, Fig. 4 shows enlarged detailed views of the position of the drive balls 8 (detail C) as well as an enlarged view of the return sleeve 6, the function of which will be explained later.

[0029] The drive balls 8 are pressed into the ball pockets 13 of the drive sleeve 9 by the pressure element 7 in the form of a sleeve seated on the shaft. Due to the conically tapered inner diameter of the pressure element 7, the balls 8 are pressed more firmly into the pockets 13, the further the sleeve is pushed onto the balls 8 in the axial direction by the disc spring 3. The output gear 10 is provided with openings / perforations 14, within which the balls can move in the radial direction. If the balls are positioned as in Fig. 3 shown within the pockets 13, there is a positive connection between the drive sleeve 9 and the output gear 10. The output gear 10 then transmits the torque to the downstream reduction gear 12 by means of running gearing. If the drive torque becomes too great due to stiffness or blockage of the reduction gear 12, the drive balls 8 press against the stop surface of the pressure element 7. If the preset contact force of the disc spring 3 is exceeded, the pressure element 7 is axially displaced to the right and the balls 8 move radially out of the ball pockets 13. If a certain radial point is then exceeded, the drive balls 8 are pressed further outwards by the special shape of the pressure element 7 until they strike the return sleeve 6. There they are held securely to prevent the clutch 5 from re-engaging unnoticed. The special shape of the pressure element is shown in detail D of the Fig. 3 and Fig. 4. It can be seen that the front edge 15 of the pressure piece 7 is inclined backwards relative to the radial axis, whereby the balls 8 striking it are pressed against the return sleeve 6 ( Fig.4, Detail D). An inclination angle of approximately 10° relative to the radial axis is sufficient.

[0030] In this open state of the clutch 5, the drive gear 10 can rotate freely on the drive shaft 1 thanks to the ball race 11. The drive sleeve 9 can now continue to rotate with the shaft 1, since the disengaged clutch 5 can rotate freely on the ball races 2 and 11. The load path between the drive shaft 1 and the reduction gear 12 is now interrupted, and the reduction gear 12 and the vane structure are now protected from overload. The reduction gear 12, thus separated from the load path, is then blocked against uncontrolled movement by a backstop.

[0031] Since the reduction gear 12 can no longer rotate in this situation, a skew of a flap driven by two or more reduction gears 12 can occur, provided at least one gear continues to operate. This skew is detected by a sensor, and the entire drive train is blocked. The cause of the stiffness or blockage of the reduction gear 12 can then be investigated and, if external to the reduction gear 12, eliminated. The tilted landing flap is then readjusted, and the load path of the reduction gear 12 can be manually reactivated from the outside.

[0032] For this purpose, the release clutch 5 provides the two reset buttons 4, which must be actuated simultaneously to engage the clutch, in particular must be pressed in the axial direction against the force of the springs 16. A corresponding stop on the cylindrical body of the reset buttons entrains the reset sleeve during the axial displacement. The shape of the reset sleeve 6 with the conically tapered inner diameter presses the drive balls 8 back into the ball pockets 13 of the drive sleeve 9 through the axial displacement. The star-shaped cross-section of the drive sleeve 9 with the tapered intermediate walls 17 between the pockets 13 facilitates the balls 8 sliding back into the pockets 13, so that this can occur regardless of the current rotational position of the drive sleeve 9.

Claims

[1] High-lift system for an aircraft with at least one mechanically adjustable flap which can be actuated by means of at least one actuator (1), wherein the actuator (1) is driven by the torque of a central drive unit (PCU) of the high-lift system, and wherein the at least one actuator (1) has an integrated release clutch (5) which interrupts the load path when a permissible response torque is exceeded, characterized by that a return means is provided to manually close the release clutch (5) after an overload situation without removing the actuator (1). [2] High-lift system according to claim 1, characterized by that the release clutch (5) is bistable. [3] High-lift system according to one of the preceding claims, characterized by that the release clutch (5) is designed in such a way as to enable clutch engagement regardless of the rotational position of the input shaft. [4] High-lift system according to one of the preceding claims, characterized by that the power transmission of the closed release clutch (5) takes place by means of balls (8) which are located in corresponding pockets (13) of the drive and / or driven wheel (10), wherein the balls (8) can be disengaged from the pockets (13) in the radial or axial direction in order to release the release clutch (5). [5] High-lift system according to claim 4, characterized by that the drive wheel of the release clutch (5) is star-shaped, ie the walls lying between the ball pockets (13) converge in a radial direction, whereby the engagement of the balls (8) for clutch closure is possible regardless of the rotational position of the drive wheel. [6] High-lift system according to one of claims 4 or 5, characterized bythat a pressure element (7) is provided which holds the balls (8) in the ball pockets (13) of the drive and / or driven gear (10) up to a certain load moment, wherein the pressure element (7) is prestressed and / or can be pushed in the axial direction against the balls (8), wherein in an overload situation the balls (8) press in the radial direction against the pressure element (7). [7] High-lift system according to claim 6, characterized by that the pressure element (7) is a sleeve whose inner radius tapers conically towards the outside, wherein the end face of the sleeve facing the balls (8) is inclined backwards with respect to the radial axis in order to hold the balls (8) in the disengaged position. [8] High-lift system according to one of the preceding claims, characterized bythat the return means comprises a return sleeve (6) with a conically outwardly tapered inner radius, wherein the disengaged balls (8) strike against the inner wall of the return sleeve (6) and can be pressed back into the pocket (13) of the drive and / or driven gear (10) by axial displacement of the return sleeve (6). [9] High-lift system according to one of the preceding claims, characterized by in that the return means comprises at least two manually operable operating means which must be operated simultaneously to close the release clutch (5), wherein the operating means are preferably designed as pre-tensioned return buttons (4) which can be pushed manually onto the return sleeve (6) in the axial direction. [10] High-lift system according to one of the preceding claims, characterized bythat at least one gear (12) is arranged between the adjustable flap and the release clutch (5), and the release clutch (5) is mounted on the drive side of the gear housing. [11] High-lift system according to claim 10, characterized by that the gear (12) comprises a backstop to prevent unintentional flap movement when the release clutch (5) is released. [12] Aircraft with at least one high-lift system according to one of the preceding claims.

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