Abstract:
An arrangement for the electrical operation of a door of an aircraft, in particular an electrical drive arrangement for the operation of cabin doors of commercial aircraft. The object of finding a new option for operating the doors of aircraft which guarantees an electrical operation of the door with high reliability and a minimum of weight is met by an arrangement for the electrical operation of a door of an aircraft by providing an electrically powered driven shaft for the operation of the door which is coupled to at least one lever arm of the door mechanism so that it rotates together with it and the rotation of which pivots the lever arm of the door mechanism by a predetermined angle. For this, at least two electrical drives independent of each other act on the driven shaft, wherein these drives are both attached to a structural part—relative to which the lever arm of the door mechanism is pivoted—via a coupling mechanism to take up torque opposing the direction of rotation, the coupling mechanism being capable of being uncoupled in direction of the rotation of each drive.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    a) Field of the Invention  
           [0002]    The invention is directed to an arrangement for the electrical operation of a door of an aircraft, in particular an electrical drive arrangement for the opening and closing and/or the locking and unlocking of cabin door of commercial aircraft.  
           [0003]    b) Description of the Related Art  
           [0004]    Customarily, cabin doors of commercial aircraft are operated manually, which has the disadvantage that when the commercial aircraft is under great wind load stress or tilted, great physical strength must be exerted which is partially compensated for by a long lever, but this also introduces disadvantages in the areas of kinematics and weight.  
           [0005]    Now and again, airplane doors are equipped with an additional electrical drive, mainly to make their operation easier for service personnel. In this case, this electrical drive is added on preferably as a linear drive in adaptation to the door mechanism and the pneumatic linear actuator usually present for supporting emergency operation and for damping the opening movement. Conventional electric drives with their functional sequence of electronics, motor, reducing gear are less reliable and the danger of the line of drive being blocked in particular on the high-speed side of the gear at the juncture with the motor exists. Such a blocking of the power take-off could be undone by means of a coupling on the gear, but this would have to be designed for the great forces occurring in the power take-off and would therefore be impractical for a door drive, especially because of the weight disadvantages.  
         OBJECT AND SUMMARY OF THE INVENTION  
         [0006]    The primary object of the invention is finding a new option for the operation of doors of aircraft which guarantees an electrical operation of the door together with high reliability and the lowest possible weight.  
           [0007]    According to the invention, this object is met for an arrangement for the electrical operation of the door of an aircraft by providing a driven shaft for opening the door that is driven electrically, wherein this driven shaft is rigidly coupled to the arm of a lever of a door mechanism so that they rotate jointly and the lever arm of the door mechanism is pivoted by a pre-determined angle by means of a rotation of the driven shaft. The opening and closing mechanism as well as the locking and unlocking mechanism can be considered for being used as the door mechanism.  
           [0008]    Advantageously, at least two electrical drives independent of each other act on the driven shaft and these drives are both attached to a structural part—relative to which the lever arm of the door mechanism is pivoted—via a coupling mechanism to take up torque opposing the direction of rotation, the coupling mechanism being capable of being uncoupled in direction of the rotation of the drive. For this, the drives could be appropriately attached to a structural part of the door, to a movable lever arm (also a structural part) of the door, or to a structural part of the fuselage.  
           [0009]    Advantageously, the coupling mechanism is realized as a blockable rotary guide, wherein appropriately removable blocking pins are inserted between the part attached to the structural part and the part attached to the drive housing.  
           [0010]    Preferably, the drives fulfill the drive function for the driven shaft at the same time, but it is also advantageous for the drives to alternate in acting in a drive function for the driven shaft, wherein here the passive drive can be switched to a state where no current and (via the coupling mechanism) no force are applied to it so that during normal operation of the door operation operativeness checks of the separate elements of the drives can be done.  
           [0011]    It is advantageous for all electrical drives to be capable of being switched to a state where no current and no force are applied to them at the same time, wherein the driven shaft is therefore freed for another way of driving the door operation, in particular by a manual operation.  
           [0012]    Suitably, the drives both have a reducing gear and a current controlled motor with control electronics. Preferably, current controlled brushless DC-motors are used as motors.  
           [0013]    On the one hand, it is advantageous for each motor to be attached by its housing via a coupling mechanism to the structural part, wherein all other elements of the drive are rigidly attached to the motor. For a particular embodiment of the drives, both motors are connected to the same gear, wherein the gear is rigidly connected to the structural part by its housing and the gear fulfills the function of a type of differential gear. On the other hand and as a suitable alternative, each gear is attached by its housing via the coupling mechanism to the structural part, wherein all other elements of the respective drive are rigidly connected to the gear.  
           [0014]    A planetary gear is preferably to be used as the highly reducing gear.  
           [0015]    The driven shaft is appropriately arranged parallel to the axes of the drives, wherein each drive has a separate gear pair for the transmission of force onto the driven shaft.  
           [0016]    In an advantageous variation, the drives could be dimensioned differently, wherein one drive is provided as a main drive and the other drive is realized as a secondary drive with less power (as an auxiliary drive in case of failure of the main drive), but a reduction of the opening speed would have to be accepted during a failure of the main drive.  
           [0017]    In another preferable embodiment form in the invention, the drives acting on the driven shafts are constructionally identical.  
           [0018]    In this case, a suitable variation has the driven shaft also arranged parallel to the axes of the drives and being driven by the drives via a shared gear pair for the transmission of force onto the driven shaft ( 1 ).  
           [0019]    A particularly compact construction is achieved for constructionally identical drives by arranging the driven shaft on the shared axis of the drives, wherein the drives have hollow shafts for this purpose. For the transmission of force onto the driven shaft, a portion of the hollow shafts of the gears with an internal gearwheel could engage in a gearwheel of the driven shaft situated on the inside, but a tongue and groove joint or another type of positive lock connection between the driven hollow shaft of the gears and the driven shaft for the door operation could also exist.  
           [0020]    The basic idea behind the invention is based on the thought that the reliability of a completely automatic drive for the electrical operation of aircraft doors is only suitably increased if a blocking of the entire door is excluded by releasing the blocking when the drive failure is recognized and making it possible to still open the door by means of a redundant drive or an emergency opening mechanism.  
           [0021]    This is to be provided according to the invention by having two drive units completely or partially independent of each other act on a shared driven shaft, and by switching one drive to a zero force state by removing the drive load moment via a coupling mechanism when necessary or in the case of failure. This coupling mechanism has to take moments similar to a gear coupling on the drive side, but it is a functional component of the housing function and has considerable weight advantages compared with a coupling. The drive units can be chosen to be operated separately or together and permit the discovery of errors during their operating time if they are driven appropriately, for example by alternatingly activating the drives or by monitoring them via sensors. The opportunity for an early reestablishment of a full functional state therefore exists.  
           [0022]    The switching to a zero force state of one of the drives relative to the driven shaft is advantageously done in the shape of a coupling mechanism between a drive housing in a rotary bearing and the door structure or the fuselage structure of the aircraft and can be brought about electrically or manually as well as hydraulically or pneumatically.  
           [0023]    With the arrangement according to the invention it is possible to guarantee the electrical operation of a door of an aircraft with great reliability and at the lowest expenditure of weight, wherein at least two electrical drives act upon a driven shaft moving levers of the door mechanism and can be switched separately to a zero force state relative to the driven shaft, and wherein in the case of an accident an emergency opening function can be realized with a suitable medium for energy storage or both drives can be separated from the driven shaft for the realization of a manual operation.  
           [0024]    Furthermore, the individual drives and their switching to a zero force state can be tested alongside the normal door operating function, and an electrical energy storage medium is easier to check than other energy storage media, so that less service measures for checking the emergency opening function must be taken.  
           [0025]    The drive arrangement according to the invention can also be applied to freight doors of aircraft, wherein using electrical drives for opening and closing them (currently mostly done by linear actuators) essentially overcomes the main disadvantage (leaking oil) of hydraulic components and increases the functional safety of the operation of the freight doors by means of the second drive.  
           [0026]    The use of the drive arrangement according to the invention is by no means limited to aviation technology, although it has been conceived particularly for this purpose because of the given weight limits and safety standards. Further essential advantages, consisting in the fact that together with increased functional reliability concepts of (electrical) emergency opening can be made possible and the maintenance rate of the door opening mechanism can be decreased, are also of great interest for any other type of automatically operated door.  
           [0027]    The invention is subsequently to be explained in more detail. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0028]    In the drawings:  
         [0029]    [0029]FIG. 1 shows a schematic diagram of the operating arrangement according to the invention;  
         [0030]    [0030]FIG. 2 shows a preferred embodiment of the coupling mechanism according to the invention;  
         [0031]    [0031]FIG. 3 shows a sectional view at right angles to the drive axis of the coupling mechanism in three different states;  
         [0032]    [0032]FIG. 4 shows an embodiment form of the drive unit with reduced components;  
         [0033]    [0033]FIG. 5 shows a design form of the invention realized with a hollow shaft; and  
         [0034]    [0034]FIG. 6 shows an advantageous basic design of the operating arrangement on an existing door opening mechanism of an aircraft. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0035]    The operating mechanism in its basic structure—as shown in FIG. 1—consists of a driven shaft  1  and two separate drive units  2 ,  3  of which each has a gear unit  21 ,  31  and a motor  22 ,  32  with control electronics  221 ,  321 . The necessary drive load moment of the rotary drive unit  2 ,  3  is in each case deflected via a coupling mechanism  24 ,  34  into a structural part  4  of the door or the frame structure.  
         [0036]    For the subsequent part, the case of the operation of an aircraft door (opening/closing, locking/unlocking), in particular a cabin door of a commercial aircraft is assumed while a general application is not excluded. The principle according to the invention can be applied to any other automatic door and is not just limited to aircraft of all types, although it has been especially conceived for the latter for the purpose of attaining a minimum weight solution.  
         [0037]    [0037]FIG. 1 is an advantageous embodiment of the invention for operating the door mechanism of an aircraft by use of which the basic principle of the invention is to be illustrated.  
         [0038]    The driven shaft  1  to which at least one lever arm of the door mechanism is coupled rigidly and which for purposes of opening or also locking the door has to be turned only by a certain angle (normally less than 270 degrees) and under a considerable load is driven by two separate motors  22 ,  32  via two gear pairs  25 ,  35  and two independent gears  21 ,  31 . The motors  22 ,  32  are operated by current control and for this driven by two electronics units  23 ,  33 . Because of the large torque and their very good capability of being current controlled, brushless DC-motors are preferably to be used. To increase the output force further, planetary gears are preferably to be provided as the gears  21 ,  31 —this also because of their rotationally symmetrical construction.  
         [0039]    The coupling mechanisms  24 ,  34  in FIG. 1 are attached to the gears  21 ,  31  for the purpose of receiving the drive load moments. They are—as shown in FIG. 2 in a longitudinal section through the coupling mechanism  24 —realized as a blockable rotary guide, wherein the rotary part  241  which is in a rotary bearing comprises a housing  212  of the entire drive  2  (in FIG. 1 the housings of gear  21  and  31  to which all the other respective elements of the drives  2 ,  3  are rigidly attached). Between the base part  242  attached to the structural part  4  and the rotary part  241  connected to a drive housing  212 , a number of guided blocking pins  243  are inserted. If necessary or in the case of an accident, the blocking pins  243  which turn the rotary guide during normal operations (coupled state) of the drive  2  into a rigid drive holder are removed from the rotary part  241  by pushing them into the base part  242 . It is also possible to realize the pin movement by lowering them into the rotary part  241 , possibly analogous to the function of the pins of a safety lock.  
         [0040]    [0040]FIG. 3 show the function principle of the coupling mechanism  24 ,  34  in three different states in a sectional view at right angles to the directions of the axes of the driven shaft  1  and the gear  21 .  
         [0041]    In the left partial view, the initial state of the left drive  2  (sectional plane S-S) shown in FIG. 1 is represented. To illustrate the principle, all components shown in a sectional view—driven shaft  1 , driven gearwheel  212  and housing  213  of the gear  21 —are marked with lines which in the initial state all have the same alignment.  
         [0042]    The central partial view of FIG. 3 shows the resulting rotational angle  111  of the driven shaft  1  after the motor  22  is activated while the gear  21  acts on the driven gearwheel  212  and the coupling mechanism  24  is coupled, meaning rigid; wherein only the base part  242  of the coupling mechanism  24  is visible, since the rotary part  241  is integrated into the housing  213  of the gear  21 . The rotation angle  211  of the driven gearwheel  212  of the gear  21  relative to the base part  242  in this case is zero. In this case, the force is transmitted to the driven shaft  1  via the drive unit  2 .  
         [0043]    The right partial view in FIG. 3 shows the resulting rotational angle  11  of the driven shaft  1  after the motor  32  (in FIG. 3 the one on the right) is activated. Because of the action of the gear  31  on the driven gearwheel  312  when coupling mechanism  34  is coupled and coupling mechanism  24  is uncoupled, the gear  21  rotates together with its housing  213  in the same direction as the driven gearwheel  212 . The rotational angle  214  of the gear housing  213  relative to the coupling mechanism  24  is here maximally equal to the rotational angle  11  of the driven shaft  1 . Via the driven shaft  1  the driven gearwheel  212  and the entire drive  2  including the motor  22  rotate along with this by means of internal friction moments (in the case of failure, blocking moments). In this case, no force is transmitted or received by the left drive  2 , since the coupling mechanism has been released from the rotation and the drive  2  has therefore been changed to a zero force state.  
         [0044]    If necessary, the control of the coupling mechanism  24  or  34  can be done by a number of trigger processes combined in a logic circuit. On the one hand, this is easily done for the current controlled motors  22 ,  32  by uncoupling the coupling mechanism  34  when a certain current value is exceeded if motor  32  is drawing too much current, or the coupling mechanism  24  is uncoupled if the motor  22  does not remain below the rated current maximum. On the other hand, the uncoupling of the coupling mechanisms  24  or  34  can be triggered by the fact that the corresponding motor  22  or  32  is not rotating in spite of being driven correspondingly, for which purpose a position sensor, for example, a rotation resolver, an encoder or a Hall sensor, is attached. A third possible safety variation provides a door opening sensor which monitors the conversion of the motor drive power into a movement of the door (for example a rotational angle or position sensor on the driven shaft  1 ) when the motor  22  and/or  32  is triggered. In a fourth variation, both motors  22  and  32  are equipped with different sensor systems, so that each motor is, for example, equipped with a current monitor (threshold) and a rotation sensor, for example, an angle sensor, so that even when, for example, the motor  22  fails, the entire drive  2  is automatically uncoupled via the coupling mechanism  24  and an error message is generated, if necessary.  
         [0045]    [0045]FIG. 4 show an embodiment form of the operating arrangement with reduced components. Here, both gears  21 ,  31  work on a shared driven gearwheel  231  and the motors  22 ,  32  are triggered by a shared electronics unit  232 . This results in weight savings with only slightly reduced reliability if additional sensors apart from the motor current monitor are there to monitor the rotation of the motors  22 ,  32 .  
         [0046]    [0046]FIG. 5 shows a particularly compact construction of the arrangement according to the invention under use of drive units  2 ,  3  constructed in a hollow shaft design. Here, the driven gearwheels  212 ,  312  shown in FIG. 2 are not necessary, since the driven shaft  1  can be connected directly to the outputs of the gears  21 ,  31  in a positive lock, for example in the shape of a tongue and groove joint. Alternatively, the transmission of force can be realized with an internal gear in the hollow shaft  233  and a gearwheel on the driven shaft  1  meshing with it. The hollow shaft construction results in a further saving of weight for the same reliability but with a more complex construction limiting constructional freedom. On the other hand, play and the need for adjustments of the driven shaft  1  and the hollow shaft  233  are reduced.  
         [0047]    [0047]FIG. 6 takes up the embodiment form from FIG. 5 and shows the possible integration of the operating arrangement according to the invention into an existing door opening mechanism. The special way in which the door mechanism functions is only of secondary importance here, since the invention only needs one rotation axis for executing the door movement. Such a rotation axis which for the arrangement according to the invention corresponds to the driven shaft  1  is as such present in all known door systems of commercial aircraft.  
         [0048]    The door mechanism shown in a stylized manner in this example is based on the assumption that the door  41  can be lifted out of the fuselage  43  as well as be guided sideways parallel to the outside wall of the fuselage  43  by means of lever arms  42  which function as support and guide arms at the same time and hold and guide the door. Even for this sequence of motions with straight-line motion components, the arrangement according to the invention can be used as a type of rotation actuator. Because of its low weight, the complete operating arrangement is even suitable for being built into a structural part  4  of the door  41 , so that even in existing door systems linear actuators that are already present could be replaced simply by changing the door construction.  
         [0049]    For the door mechanism chosen for FIG. 6, the door is—according to the view from below—rotated relative to a lever arm  42  (“support arm”) and further lever arms  42  in the sense of a guiding rod system (“guide arms”) with which no drive  2 ,  3  engages and of which only one is shown in place of all of them take over the forces necessary for guiding the door  41 .  
         [0050]    The same lever arms  42  can be operated by the operating arrangement according to the invention even if the drives  2 ,  3  are attached to the structure of the fuselage  43  (not shown). Even attaching them to the lever arm  42  functioning as a “support arm” (or between two such arms situated vertically above each other, also not shown) can by all means be realized.  
         [0051]    The top side view shows again the embodiment form of the invention according to FIG. 5 put together as complete hollow shaft drives  2 ,  3  with a stylized indication of the coupling mechanisms  24  and  34 . The driven shaft  1  is embedded in both hollow shafts (not visible) and has for the purposes of force transfer onto the driven lever arm  42  an eccentric disk  5  with guide pins  13  with the rotation of which the lever arm  42  is pivoted on the lever joint  44  and relative to the door  41 . Because of the effect of the guiding lever arm  42 , which like the driven lever arm  42  is connected to the structure of the fuselage  43  in a manner that permits its rotation, the door  41  is moved essentially laterally to the direction of the driven shaft  1  in a parallel orientation relative to the outside wall of the fuselage—according to the top view in FIG. 6—depending on the direction of rotation of the drives  2 ,  3 .  
         [0052]    As it has been emphasized a number of times before, the operating arrangement according to the invention is not limited to aircraft doors with straight-line mechanisms but can also be applied to doors pivoted on a rotation axis by building the driven shaft  1  of the operating arrangement into this rotation axis.  
         [0053]    While the foregoing description and drawings represent the present invention, it will be obvious to those skilled in the art that various changes may be made therein without departing from the true spirit and scope of the present invention  
                                         LIST OF REFERENCE NUMBERS                                 1   Driven shaft 1        11   Angle of rotation        12   Eccentric disk        13   Guide pin        2, 3   Drive       211   Angle of rotation (of the driven gearwheel)       212, 312   Driven gearwheels       213   Housing       214   Angle of rotation (of the gear housing)        21, 31   Gear        22, 32   Motor       221, 321   Control electronics       231   Shared driven gear pair       232   Shared electronics unit       233   Hollow shaft        24, 34   Coupling mechanism       241   Rotary part       242   Base part       243   Blocking pin        4   Structural part        41   Door        42   Lever arm        43   Fuselage        44   Lever joint