Abstract:
A high-lift system on a wing of an aircraft is provided. The wing includes a right-hand and a left-hand wing half with movably held high-lift flaps and the right-hand and left-hand wing half are attached to an aircraft fuselage, thus forming a wing root. Each wing half in a region in close proximity to the wing root, includes a drive unit. In each case this drive unit is joined to a transmission shaft mechanically connected to the respective drive unit, which transmission shaft extends from the drive unit in the direction of the end of the respective wing half and is designed to mechanically move the high-lift flaps arranged in the respective wing half. By means of such an arrangement it is possible to do without deflection gear arrangements from a central drive unit to the individual wing halves.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This is a continuation of International Application No. PCT/EP2011/067407, filed Oct. 5, 2011, which application claims priority to German Patent Application No. 10 2010 047 512.2, filed Oct. 5, 2010 and to U.S. Provisional Patent Application No. 61/389,961, filed Oct. 5, 2010, which are each incorporated herein by reference in their entirety. 
    
    
     TECHNICAL FIELD 
     The technical field relates to a high-lift system for an aircraft comprising a multitude of movable lift flaps and to an aircraft comprising a high-lift system with a multitude of movable flaps. 
     BACKGROUND 
     Many high-lift systems with movable flaps in civil and military aircraft are driven by way of a central drive unit located in the middle of an aircraft fuselage, which drive unit is also known as a power control unit, PCU, a transmission shaft train and local mechanical actuator devices on corresponding flap support stations of the movable flaps. The actuator devices are frequently designed as linear spindle drives or rotary drives. In addition, these known high-lift systems comprise safety brakes, for example so-called “wing tip brakes” (WTB), which go into action in certain instances. Usually, controlling and monitoring these high-lift systems takes place by means of digital on-board computers of the aircraft, for example by means of a so-called “slat flap control computer” (SFCC). 
     Based on the central drive unit, synchronicity between individual flaps of a left-hand and a right-hand wing half, as well as between the flaps of a wing half, is ensured mechanically by means of the transmission shaft train that extends through the fuselage and along the support stations. This transmission shaft train usually comprises a multitude of bearings, multiple tooth elements, universal joints and, for the purpose of bridging large changes in direction, in particular relating to the region from the fuselage centre to the wing halves or to the wing root region, corresponding angular gear arrangements. The central drive unit for flaps on a leading edge of the wing and for flaps on a trailing edge of the wing is, for example in the case of aircraft made by AIRBUS, installed in close proximity to the fuselage center line in the landing gear bay or in the region of the wing-fuselage fairing (“belly fairing”). In each case a central drive unit for the flaps of the leading edge of the wing, and a central drive unit for the flaps of the trailing edge of the wing are used. The respective central drive unit is usually driven by two motors that are active in parallel, with the drive output of said motors being transferred to the respective transmission shaft system by way of a differential, wherein several drive modes exist. 
     EP 1 462 361 B1 and U.S. Pat. No. 7,048,234 B2 show a flap system on the wing of a fixed wing aircraft, in which system flaps are coupled to synchronized wing-internal individual drives. 
     In addition, other objects, desirable features and characteristics will become apparent from the subsequent summary and detailed description, and the appended claims, taken in conjunction with the accompanying drawings and this background. 
     SUMMARY 
     Arranging the central drive unit in the region of the fuselage centre for a respective flap system on the leading edge of the wing and on the trailing edge of the wing, respectively, results in very considerable installation expenditure with a multitude of mechanical components such as transmission shafts, universal joints, bearings and bearing positions, as well as angular gear arrangements, in order to first bring the shaft output of the drive unit to the wing halves or to the region of the wing root. While torque transmission within the fuselage usually requires very substantial changes in angle, torque transmission within the wing halves takes place in quite a rectilinear manner. 
     From the point of view of expenditure, weight and, in particular, control technology, synchronized coupling of flaps comprising individual drives is more involved and provides lower overall reliability when compared to coupling all the flaps that are to be driven by means of a shared transmission shaft. 
     The present disclosure provides a high-lift system for an aircraft, which system can accomplish simple drive of flaps on a leading edge of the wing and flaps on a trailing edge of the wing, respectively, with as few pronounced changes in angle as possible, without in this arrangement increasing the weight, and in particular without reducing the reliability of the aircraft. 
     A high-lift system on a wing of an aircraft, which wing comprises a right-hand and a left-hand wing half with movably held high-lift flaps, is attached to an aircraft fuselage, thus forming a wing root. According to various aspects of the present disclosure, in each wing half in a region in close proximity to the wing root a drive unit is arranged, which in each case is joined to a transmission shaft mechanically connected to the respective drive unit. Said transmission shaft extends from the drive unit in the direction of the end of the respective wing half and is designed to mechanically move all the high-lift flaps arranged in the respective wing half. 
     According to the present disclosure, thus two drive units that are non-central and that are operable independently of each other are used, which replace a central drive unit and its necessary deflections into the wing halves. This provides an advantage in that the displacement of the drive units to a region in close proximity to the wing root obviates the need for expensive displacement of the transmission shaft from the fuselage center to the wing halves or to the wing root. The drive units that have spatially been displaced to the wing root region can easily and advantageously be installed, in particular in the case of aircraft comprising fuselage landing gear, because in this arrangement there usually is sufficient installation space, in particular for a trailing edge flap system. As a result of the displacement of the drive units approximately a quarter of the transmission shafts of conventional transmission shaft systems that are centrally driven and that emanate from the fuselage center can be done without. Furthermore, there is no need to provide the associated angular gear arrangements that are usually installed in order to bridge the large changes in angle of the transmission in the fuselage region. Doing without these mechanical drive components such as transmission shafts, universal joints and angular gear arrangements, as well as doing without the associated structural connections or bearings in this region, potentially results in reduction in the weight of the overall system, in other words in a weight-optimized drive both in relation to the high-lift flaps on a leading edge of the wing, and in relation to the high-lift flaps on a trailing edge of the wing. The overall weight of the now doubled number of drive units is potentially lower than the overall weight of a central drive unit and the necessary deflection means to the wing halves. Furthermore, it should be taken into account that each of the two drive units needs to cope with a significantly lower mechanical load than the central drive unit so that this results in smaller dimensioning which has a positive effect on the overall weight achieved. 
     The present disclosure provides a further advantage in that it involves a significantly reduced installation effort, in particular because no transmission installation in an already confined installation space, which is already used by many other systems, in the landing gear bay and in a wing-to-belly transition region is required. 
     At this stage it should be pointed out that it is also possible to install several high-lift systems according to the present disclosure in order to replace several drive units and transmission shaft trains. It is imaginable for a high-lift system according to the present disclosure to be equipped with leading edge flaps, and for a high-lift system according to the present disclosure to be equipped with trailing edge flaps and to be installed on a wing. It is further pointed out, that the expression “flap” includes trailing edge flaps, leading edge flaps and other movably held flaps of an aircraft, wherein leading edge flaps may also include slats. 
     In one exemplary embodiment the high-lift system in each wing half in each case comprises at least one actuator device that is mechanically connected to the transmission shaft and to the high-lift flaps to be moved, wherein the drive unit, when viewed in the direction of the wingspan, is arranged closer to the wing root than a first actuator device. This means that in each wing half a drive unit is arranged in close proximity to the wing root region, and from this drive unit a transmission shaft extends into the wing half and, extending in the direction of the wing tip, a first actuator device and optionally further actuator devices follow on. This arrangement provides an advantage in that the drive unit in question needs to provide only one transmission shaft outlet, which extends to all the actuator devices within a wing half. 
     In one exemplary embodiment the high-lift system comprises two or more actuator devices, wherein the drive unit, when viewed in the direction of the wingspan, is positioned between a first actuator device and a second actuator device. This arrangement provides an advantage in that an additional transmission shaft from the drive unit to the first actuator device can be done without so that as a result of this it would be possible to save weight. 
     In one exemplary embodiment the high-lift system according to the present disclosure comprises two control computers that are independent of each other, which are both connected to the left-hand and the right-hand redundant drive unit and are designed to acquire current desired positions and actual positions of high-lift flaps to be moved, and to control the drive unit to equalize the actual positions to the target positions. Acquiring the actual positions can, for example, be achieved by means of position sensors situated on the high-lift flaps, on actuator devices, on the drive units or on the transmission shaft. By inputting target positions, for example by means of a corresponding signal from a pilot, both control computers will control the drive units in such a manner that on the two wing halves the input target positions are attained synchronously. 
     In one exemplary embodiment a roll compensation unit is connected to the drive units and is designed to equalize differences in lift between the right-hand and the left-hand wing half, in that by means of over-controlling the respective drive unit a balanced differential rolling moment is generated. In this way, mechanical adjustment of landing flaps for roll compensation, which mechanical adjustment is usually carried out following initial functional check flights, can be done without. The roll compensation unit can be designed as a separate unit but at the same time can also be integrated as an algorithm in the control computers. 
     The present disclosure also provides an aircraft comprising a wing with two wing halves and a high-lift system described above. The aircraft designed in this manner has clear weight advantages when compared to known aircraft comprising conventional high-lift systems, and manufacturing costs are reduced because there is no need to provide angular gear arrangements and the like that are expensive to install. 
     Furthermore, the present disclosure provides the use in each case of a drive unit and a transmission shaft, in each wing half of an aircraft with a wing, for moving high-lift flaps that are movably arranged on the wing. 
     Lastly, the present disclosure also provides a method for moving high-lift flaps, movably held on a wing comprising two wing halves, with two drive units arranged in the wing halves, with each drive unit being connected to a transmission shaft that extends into the respective wing half and that is coupled to actuator devices. Such a method according to the present disclosure essentially comprises rotating the transmission shafts; measuring the positions of the high-lift flaps; comparing with a target position; and, when a target position has been reached, stopping the drive units. In one exemplary embodiment of the method any asymmetry is determined by comparing opposite high-lift flaps of the two wing halves, and if there is any asymmetry the drive units are stopped. By superimposing a distance increment on a specified actual position for high-lift flaps of one wing half it is possible to compensate for asymmetry errors due to manufacturing tolerances. To provide roll compensation in the case of malfunctions, for example engine malfunction or control surface malfunction, high-lift flaps on one wing half can deliberately be extended so that they are asymmetrical. 
     A person skilled in the art can gather other characteristics and advantages of the disclosure from the following description of exemplary embodiments that refers to the attached drawings, wherein the described exemplary embodiments should not be interpreted in a restrictive sense. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The various embodiments will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and wherein: 
         FIG. 1  shows a high-lift system according to the state of the art. 
         FIG. 2  shows a high-lift system according to the present disclosure. 
         FIG. 3  shows an aircraft with two high-lift systems according to the present disclosure installed therein. 
         FIG. 4  shows a diagrammatic block-based view of a method according to the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The following detailed description is merely exemplary in nature and is not intended to limit the present disclosure or the application and uses of the present disclosure. Furthermore, there is no intention to be bound by any theory presented in the preceding background or the following detailed description. 
       FIG. 1  shows a high-lift system from the state of the art, comprising a central drive unit  2  or power control unit (PCU) which in each case by way of a transmission shaft train  4  is connected to actuator devices  6  in a left-hand wing half and in a right-hand wing half. The central drive unit  2  comprises a position sensor  8  which is also named “feedback position pickoff unit” (FPPU). Furthermore, for reasons of redundancy the central drive unit  2  is driven by two motors that are supplied with power by two different hydraulic systems. As an example  FIG. 1  shows a “green” hydraulic system  10  and a “yellow” hydraulic system  12 , which in the figures are designated “G” (Green) and “Y” (Yellow). In order to hold the system in the prescribed position and in order to counteract, during the method, any load-induced undesirable rotation of the central drive unit  2  if there is a loss of pressure by one of the hydraulic systems  10  or  12 , corresponding pressure loss brakes (“pressure off brakes”, POB)  14  are arranged which when pressure is applied are opened, and when pressure drops are closed. For the purpose of monitoring the high-lift system for asymmetries between high-lift flaps  16 , which as an example are designed as trailing edge flaps, or between high-lift flaps  18  of two wing halves so-called asymmetry position sensors  20  (“asymmetry position pick-off units” APPU)  20  are used, which are located at the end of each of the transmission shaft trains  4 . Furthermore, in the outer regions of each of the wing halves in each case a further wing tip brake (“wing tip brake”, WTB)  22  is arranged. 
     The central drive unit  2  is in connection with two control computers (Slat/Flap Control Computer  1  and Slat/Flap Control Computer  2 , SFCC  1 , SFCC  2 )  24  and  26  which monitor deflection of the flaps  16  and  18  by way of the position sensor  8  and the asymmetry sensors  20 , and thereafter control the central drive unit  2 . The control computers  24  and  26  obtain the target value to be set, for example by way of an actuating lever  28  that can be operated by a pilot, which actuating lever  28  is connected to the control computers  24  and  26 . 
     The high-lift system according to the present disclosure, shown in  FIG. 2 , differs from the state of the art shown in  FIG. 1  in that two separate and mechanically independent drive units  32  that can be operated independently of each other and that are arranged in a region of a wing root  30  are used, with each drive unit  32  by itself supplying mechanical power to a transmission shaft train  34  of a left-hand wing half or of a right-hand wing half, in which wing halves several actuator devices  36   a - 36   d  for moving high-lift flaps  16  and  18  are arranged and connected to the respective transmission shaft train  34 . 
     As an example, in  FIG. 2  the respective drive unit  32  is arranged in the direction of the wingspan, i.e. from a wing root towards the outside in the extension along the wingspan in front of a first actuator device  36   a  so that the respective transmission shaft train  34  extends from the respective drive unit  32  to a wing tip through several actuator devices  36   a - 36   d . As an alternative to this, the drive units  32  could be situated between a first actuator device  36   a  and a second actuator device  36   b , as indicated by dashed lines. From the drive unit  32  a shaft piece in the form of a section of a transmission shaft would extend to the first actuator device  36   a.    
     Because of the separation into two drive units  32  that are independent of each other the latter can be dimensioned so that they are significantly smaller than an individual central drive unit  2 . Both drive units  32  together should have an overall weight that is only slightly above the weight of an individual central drive unit. By being able to do without a number of shaft joints or angular gear arrangements, since it is not necessary to deflect rotation, in a wing root, of a central drive unit by means of several deflections in several spatial directions to corresponding junctions within a wing, the overall weight of both transmission shafts  34  together is significantly reduced when compared to that of a single centrally controlled transmission shaft train. In the final analysis this results in the overall weight of the design of  FIG. 2  being lower than that of  FIG. 1 . 
     In addition to the weight advantage it should, in particular, be stressed that by individually controlling the two drive units  32  by way of a roll compensation function in the two control computers  24  and  26  or by way of a separate, additional, roll compensation unit  38 , roll compensation can be carried out. This takes place in the form of superimposing distance increments for generating differential rolling moment by means of the high-lift flaps  16  and  18  by way of the individual, specified, actuating distances. In this way, asymmetries due to tolerances in the manufacture of the aircraft can be compensated for, and in the case of engine malfunction this can result in reducing the load on ailerons and rudders, which again provides the primary actuating surfaces of the aircraft with more roll authority for this malfunction state. If there is a generally present reduced roll authority of the actuating surfaces of ailerons and spoilers, due to a malfunction of one or several of these actuating surfaces, by means of roll compensation with the use of the high-lift flaps  16  and  18  controllability of the aircraft can be improved. 
     By comparing the actual positions supplied by the individual position sensors  40  by means of the control computers  24  and  26 , it is possible to detect whether there is any asymmetry between the flaps  16  and  18  of the two wing halves  44  and  46  so that the respective drive unit  32  that moves ahead can be braked in order to counteract defect-induced asymmetries and in so doing counteract roll moment that is to be compensated for by way of ailerons, or to ensure synchronous symmetrical extension. In this process, superimposed distance increments are to be taken into account which are input by the roll compensation unit  38  and which are desirable. 
     As a result of smaller dimensioning of the drive units  32 , doing without all the transmission shaft components plus a wing box to the wing root  30 , the weight of the high-lift system according to the present disclosure is lower than that of a high-lift system from the state of the art. Furthermore, as a result of separate control and the integrated option of roll compensation based on the omitted rigid mechanical coupling of the actuator devices of the individual wing halves, additional functions can be carried out which otherwise would have necessitated manual setting, or the like, of the actuator devices. 
       FIG. 3  shows an aircraft  42  with a high-lift system each for articulating leading edge flaps  48  and trailing edge flaps  16  and  18 , with each high-lift system comprising two separate drive units  32 , each driving an independent transmission shaft train on each wing half  44 ,  46 . 
     Finally,  FIG. 4  shows a representation of a method according to the present disclosure that comprises moving high-lift flaps and the characteristic of roll compensation. By transmitting  50  a movement signal from the control computers  24  and  26  to the individual drive units  32  the drive units  32  are driven, which results in rotation of the transmission shafts  34  and thus movement  52  of the high-lift flaps. After a stop signal has been transmitted  54 , stopping  56  of the drive units  34  takes place. 
     Parallel to this, in order to ensure the correct position of the high-lift flaps and in order to avoid asymmetry errors or the like, measuring  58  of the current position of the high-lift flaps  16  and  18  of the left-hand wing half  44  and measuring  60  of the current position of the high-lift flaps  16  and  18  of the right-hand wing half  46  takes place. Comparing  62  the present positions with target positions provides a result as to whether the transmission shafts  34  have carried out adequate rotation to reach the target positions. When said target position is reached a stop signal is emitted  54 , which results in the drive units  32  stopping. Furthermore, because the actual positions of the high-lift flaps  16  and  18  of both wing halves  44  and  46  are available, and by comparing the actual positions of opposite high-lift flaps  16  and  18 , it is easily possible to detect  64  any asymmetry in order to then emit  54  a stop signal. 
     If there is any asymmetry due to tolerances in the manufacture of the aircraft, if asymmetry is desired, or if the primary control surfaces are to be supported, by means of a roll compensation unit  38  a distance increment, i.e. an additional actuating distance, which leads to asymmetry, for particular high-lift flaps of a wing half  44  and  46  is superimposed  66  on the target position so that this does not result in switching a drive unit  32  off as a result of asymmetry. 
     While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the present disclosure in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope of the present disclosure as set forth in the appended claims and their legal equivalents.