Abstract:
A device for opening or closing an aircraft door includes an electric motor; a connector to connect the motor, and a driver. The driver includes a screw and nut system having a screw rotationally driven by the motor. The driver is configured to drive continuously and in sequence the connector with the door in a translational movement along one preset direction and then in rotational movement.

Description:
BRIEF SUMMARY OF THE INVENTION 
     The present invention relates to a motorized device for opening and closing an aircraft door. 
     An aircraft door, especially a door intended for passengers to go through during boarding and exiting, opens and closes in a particular way. Opening such a door is generally done in three phases: the door is first unlocked. In a second phase, the door is then raised for it to release along a preset trajectory. Finally, the third phase of opening itself is provided during which the door “pivots”, or more precisely clears the entrance, by a circular translation movement. Closing the door is done by an inverse procedure of that used for opening thereof. 
     The document EP-0,465,785 describes a kinematics for an airplane door in which said door pivots outward for opening and returns by pivoting into the fuselage structure for closure and is then brought into a mechanically locked position relative to the fuselage structure. In the door described, the transmission of forces resulting from the interior pressure of the cabin takes place through position stops or levers and the door, during pivoting operation, is held by means of a guide-support with one end near the fuselage and one end near the door. Electric motors are provided for being program controlled for the pivoting, closing and locking actions and also for the inverse functions such that the various functions take place in a coordinated manner because of stored programs. 
     Several motors are provided here and, although this document from the prior art claims a reduction in mass, the presence of these motors and corresponding mechanisms makes the control system heavy and complex. 
     In its preamble, the document WO-2012/110,569 summarizes the state of the technical art concerning assisted aircraft door opening systems. It in turn proposed an aircraft or spacecraft door system comprising a door and an actuator intended to actuate the door. The actuator includes an actuator drive mechanism which moves the door relative to the aircraft or spacecraft, a detection device which determines door and/or actuator movement information, an actuator control unit which controls the actuator on the basis of the movement information and also an actuator housing surrounding the actuator drive mechanism and the actuator control unit. 
     In the embodiment described in this document from the prior art and illustrated in the drawing, manual unlocking and manual locking of the door under consideration is provided. Furthermore, only the opening (and closing) operation strictly speaking is motorized. 
     The present invention then has the objective of providing a motorized aircraft door opening and/or closing device simplified compared to existing devices and making use specifically of a limited number of motors. 
     Thus with a device according to the present invention, a displacement along a substantially vertical direction of the door involved and a circular translation movement can be achieved specifically through the use of a single motor. Here it is suitable to provide a relatively quick vertical movement without however having an overly sudden opening of the door. 
     Advantageously with the device according to the invention, the door can be held in open position, preferably also in any intermediate position. 
     For this purpose, the present invention proposes a motorized device for opening and/or closing an aircraft door comprising an electric motor. 
     According to the present invention, the motorized device furthermore comprises: 
     means for connection with the door, and 
     means for driving comprising a screw/nut system with a screw rotationally driven by the motor where said drive means are suited for driving continuously and in sequence the means for connection with the door in a translational movement along one preset direction and then in rotational movement. 
     With the solution proposed by the present invention, a double movement of the door can thus be executed with a single motor. Here motor is understood to mean drive means acting on a single shaft. In aeronautics, electrical systems are conventionally redundant. Then for example, two motors will be nested one behind the other or two motors will be nested in a single housing with distinct windings. 
     In a motorized device according to the invention, the means for connection with the door comprise, for example, a pivoting arm. 
     In a preferred embodiment, a device according to the invention is a motorized device for opening and/or closing an aircraft door associated with a pivoting arm comprising an electric motor fixed on a support and coupled to a screw so as to be able to rotationally drive the screw, a nut for a screw/nut system engaging with said screw, where the screw drives the pivoting arm in translation. The motorized device furthermore comprises: 
     a coupling system with a first coupling part rigidly connected to the screw and a second coupling part complementary to the first coupling part and mobile relative thereto between at least one coupled position in which the first coupling part drives the second coupling part and at least one decoupled position in which the two coupling parts are independent of each other, and 
     a reduction gear with an entry part, called entry shaft, rigidly connected to the second coupling part and an output part rotationally driven by the entry shaft with a reduction ratio and called exit ring gear, where the exit ring gear is connected with the pivoting arm so as to be able to rotationally drive it. 
     The combination here of a coupling (or clutch) system with a reduction gear is particularly advantageous. This way a relatively significant rotation speed can be used for the phases of unlocking and lifting the door (during opening) and a reduced rotation speed can be used for the opening phase itself, which thereby avoids a sudden opening of the door, where everything is done in a time corresponding to the usual time for opening a door, or less. 
     Furthermore, the proposed kinetics is adjustable and therefore can be adapted to any aircraft door, whatever its size, weight, etc. 
     To make the maneuver easier and to limit the torque necessary from the motor used, the screw/nut system used in the motorized device according to the invention is advantageously a screw/nut system with rolling elements, for example a screw/nut system with balls or rollers. In this way, the mass of the assembly can especially be reduced. 
     A claw clutch can for example be provided for the coupling system. Such a clutch is perfectly suited to the present application; it is reliable, has a reduced mass and has an attractive price. 
     To get attractive reduction ratios, the reduction gear advantageously comprises a planetary gear train. Other types of reduction gears can also be considered here. However preference will be given to systems having a fairly high reduction ratio (greater than 50 considering the ratio of the input speed to output speed). Here a preferred implementation provides for the reduction gear to comprise a first ring with teeth, a second ring whose diameter is different from that of the first and with teeth that have the same size as those of the first ring and concentric therewith and for the reduction gear to furthermore comprise a deformation inducing element that deforms the second ring such that in at least two positions the teeth of both rings are engaged and separated by at least one position where the teeth are not engaged so as to propagate on the perimeter of the second ring a deformation wave causing a relative rotation of the second ring relative to the first. Such a reduction gear corresponds for example to a reduction gear as described in the document FR-1,146,998. 
     To increase the precision of the device according to the invention, the invention furthermore advantageously comprises a structure fixed relative to the support for the motor and means of guiding between the pivoting arm and the fixed structure. In a preferred embodiment, these means of guiding comprise a groove and a finger whose shape is suited for sliding in said groove. It doesn&#39;t matter whether the groove is made on the fixed structure or on the pivoting arm. 
     To limit the forces in the reduction gear, the device according to the invention can also be arranged to comprise a structure fixed relative to the support of the motor having a groove parallel to the screw of the screw/nut system and also a finger which can slide in said groove and fixed on the exit ring gear. The negative feedback during the pivoting of the arm is thus transmitted to the fixed structure and not to the reduction gear. 
     In order to be able to implement a locking of the system, the motorized device according to the invention advantageously comprises disengageable means of locking which act, for example, on the screw of the screw/nut system or else on the motor shaft of the electric motor. Acting on the motor shaft at the electric motor then has the advantage of the maximum reduction ratio for implementing the locking. Thus, a preferred embodiment for these locking means provides for them to comprise a first coupling disk rigidly connected to the motor shaft, and a second coupling disk rotationally locked and arranged opposite the first coupling disk, means of elastic pre-stressing acting on the second coupling disk in a manner to allow coupling between the first coupling disk and the second coupling disk, and a coil acting on the second coupling disk against the means of elastic pre-stressing when it is powered with an electric current. In this embodiment, if an electric power outage occurs, the system is locked and is thus safe. 
     The present invention also relates to an aircraft door characterized in that it comprises a motorized device as described above. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Details and advantages of the present invention will become clearer from the following description made in reference to the attached schematic drawing in which: 
         FIG. 1  is an elevation view of an embodiment of a motorized device according to the present invention. 
         FIG. 2  is a partial perspective view of the motorized device from  FIG. 1 . 
         FIG. 3  is a perspective view of a detail at a different viewing angle than that of  FIG. 2  and at an enlarged scale showing the means of guiding implemented in the motorized device from  FIGS. 1 and 2 . 
         FIG. 4  is an explanatory schematic view corresponding to the means of guiding illustrated in  FIG. 3 ; and 
         FIG. 5  is a detailed view in longitudinal section of locking means which can be implemented with a motorized device such as illustrated in  FIGS. 1 to 3 . 
         FIG. 1  shows a motorized device intended to open and close an aircraft door, not shown. The person skilled in the art knows such an aircraft door such as described in the preamble of the present document. The door in question here opens and closes by a circular translation movement. An aircraft door closes a passage made in an aircraft fuselage. To clear this passage, the door comes to a position next to the passage made in the fuselage and outside thereof. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Opening of such an aircraft door is done in three distinct phases. During a first, or unlocking, phase, the door is unlocked. During a second, or lifting, phase, the door is raised so it comes clear along a well-defined trajectory, usually by means of guiding by rollers. The last, or pivoting, phase corresponds to opening of the door, properly speaking. During this phase, the door undergoes circular translation movement through about 110 to 130°. To achieve this movement, the door is mounted on a pivoting arm. This door is pivotably mounted both around a substantially vertical axis connected to the aircraft fuselage and also around a substantially vertical axis connected to the door. This pivoting arm bearing the door is, for example, combined with a guiding rod so as to define a parallelogram and to thereby guide the door in its opening movement. 
     In  FIG. 1 , a part of a pivoting arm  2  corresponding to a pivoting arm as described above is shown. This pivoting arm  2  is combined with a motorized device described below. 
     The motorized device comprises first a motor  4 , a screw/nut system and a reduction gear  6 . The motor  4  is attached on a support  8  rigidly connected to the aircraft fuselage. This support  8  also carries a fixed structure, subsequently called housing  10 , serving especially for attaching and holding the motorized device. 
     The motor  4  can be any known type of electric motor. Preferably it involves a motor with reduction gear including a brush type motor or a brushless motor or a brushless motor with external rotor, etc. Here it will be assumed that it comprises one housing and one traversing motor shaft  5 . Both ends of the motor shaft  5  are then accessible. One end of the motor shaft  5  can be combined with a reduction gear thus forming a motor with reduction gear assembly. Conventionally in aeronautics, electrical systems are duplicated for safety. A second motor, not shown, is then also coupled to motor shaft  5 . The second motor can come with a separate housing or be integrated into the same housing as motor  4 . 
     The motor  4  drives a screw  12  from the screw/nut system which is directly mounted on the output of the motor with reduction gear. It will subsequently be assumed that the screw  12  extends along a vertical axis and that the motor  4  is positioned lower than the screw  12 . 
     The screw  12  is thus held in lower position by the motor  4  (attached on the support  8  thereof), in intermediate position by an intermediate bearing  14  born by the housing  10  and in upper position by a stop  16  itself also made in the housing  10 . The screw  12  here serves as pivoting axis for the pivoting arm  2 . This pivoting arm thus has two ears  18  inside of which are arranged in each one a bearing for guiding the pivoting arm  2  relative to the pivoting axis thereof. The lower ear  18  has a housing inside of which is located a nut engaging with the screw  12 . This nut is mounted so that it can turn freely around the axis of the screw  12  relative to the pivoting arm  2  but is trapped along the longitudinal direction (relative to the screw  12 ). The screw is thus, for example, mounted in a housing arranged in the lower ear  18  by means of two ball bearings and between two axial stops. 
     In  FIG. 1 , the presence of a first coupling part forming a stop disk  20  can also be seen where the disk has the shape of an annular part fixed on the screw  12  so as to be driven rotationally therewith but keeping a fixed axial position, which could be adjustable, relative to the screw  12 . As can be seen, this stop disk has at least one claw  22  extending axially downward. Advantageously at least two claws  22  regularly arranged around the screw  12  are provided. Such a claw  22  is also called “wolf tooth”. 
     This first coupling part is intended to engage with the second coupling part visible in  FIG. 2 . The second coupling part is subsequently called the mobile disk  24 . This disk has an overall shape similar to that of the stop disk  20 , meaning that of a disk with claws  22 . Here however, the claws  22  are oriented upward so as to be able to engage with the claws  22  of the stop disk  20 . Each claw  22  has a straight edge and a chamfered edge oriented along the direction of rotation of the screw  12  to enable a progressive coupling of the two coupling parts. 
     The mobile disk  24  is itself arranged around the screw  12  but is not driven thereby. It is intended to be driven in rotation by the stop disk  20  as will be explained below. 
     The mobile disk  24  is fixed on the reduction gear  6 . The reduction gear  6  can be made up of any type of reduction gear that can be adapted here. For reasons of bulk and also transmitted torque, a reduction gear will be chosen here having the shape of an planetary gear train or else with the shape of a reduction gear such as sold under the Harmonic Drive brand (and whose principle of operation is described in the document U.S. Pat. No. 2,929,265 or FR-1,146,998). 
     Whatever the type of reduction gear  6 , it is assumed that it comprises an entry shaft rigidly connected with the mobile disk  24 . The entry shaft is for example a hollow shaft mounted around the screw  12  and the mobile disk  24  is attached (by screwing for example) on the upper front surface thereof. The reduction gear  6  has a reduction ratio 1:N and the rotational movement of the entry shaft is transmitted to an output part, here called exit ring gear  26 , itself also mounted around the screw  12  and which turns then with a rotation speed N times less than the entry shaft. The exit ring gear  26  is fixed on the lower ear  18  and therefore drives the pivot arm  2  in rotation when it turns To limit the forces on the internal mechanism of the reduction gear  6 , a finger  28  is fixed to the periphery of the exit ring gear  26  and extends radially outward. This finger  28  engages in a groove arranged in a constituent branch  30  of the housing  10 . The branch  30 , just like the groove arranged therein, extends vertically, meaning parallel to the screw  12 . 
     A guide is made between the pivoting arm  2  and the housing  10 , meaning between the arm and a structure fixed relative to the aircraft fuselage. To implement this guide, as shown in more detail in  FIG. 3 , a cam  32  is attached on the housing  10  (not shown in  FIG. 3 ) extending towards the pivoting arm  2  whereas a guide  34  is attached on the surface of the pivoting arm  2  opposite the cam  32 . In the embodiment shown in the drawing, arranging the cam  32  such that the guide  34  is located between the two ears  18  of the pivoting arm  2  was selected. 
     The guide  34  has a vertical groove  36  and a horizontal edge  38  with a circular arc shape intended to press against the cam  32 . 
       FIG. 5  illustrates a locking system which is preferably housed under the motor  4  but which could for example be placed between the motor  4  and the screw  12  or else also be housed in the intermediate bearing  14  or else in the stop  16 . 
     Here it is proposed to rigidly connect a first clutch disk  40  to one end of the motor shaft  5  opposite the screw  12  using a key (not shown). A second clutch disk  42  with suitable dimensions then comes against opposite the first clutch disk  40  and friction plates  44  are provided on one and/or both clutch disks. 
     The second clutch disk  42  is assembled in a box  45 , attached for example to the housing of the electric motor  4 , so as to be able to move axially (the motor shaft  5  and the screw  12  here determine the axial direction) relative to said box  45 , but without possibility of pivoting around the motor shaft  5 . Furthermore, the second clutch disk  42  is prestressed by a spring  46  against the first clutch disk  40 , where the spring  46  comes for example to press against an inner surface of the box  45 . 
     A coil  48  is mounted to the periphery of the second clutch disk  42  inside the case  45 . When the current (fairly intense) passes through this coil  48 , it holds the second clutch disk  42  away from the first clutch disk  40  and against the spring  46 . 
     The operation of this device for aircraft door opening and closing is described below. 
     The motor  4  (motor with reduction gear) rotationally drives the screw  12  with bearings. So that the motor  4  can operate, the locking system is deactivated by sending current through the coil  48  ( FIG. 5 ). 
     During rotation thereof, the screw  12  with bearings first drives the nut with bearings located in the lower ear  18 . Rotation of the screw  12  drives translational displacement of the nut with bearings. The pivot arm  2  is translationally driven with the nut with bearings by being guided by the guiding system comprising the cam  32  and the guide  34 . 
     The rising of the nut and the pivot arm  2  continues. This rising phase corresponds to the phase of unlocking/lifting the aircraft door. During this phase, the door is itself also guided, for example by means of guiding provided in the area of the doorframe. 
     At the end of the rising phase, the pivoting arm  2  is brought to pivot in order to allow the opening of the door. At this moment, the cam  32  then leaves the grove  36  of the guide  34 . This exit out of the groove  36  also corresponds to the beginning of the coupling between the mobile disk  24  with the stop disk  20 . The claws  22  then come to hold on each other. The stop disk  20  and the guide  34  are positioned such that the exit of the cam  32  out of the groove  36  coincides with the coupling of these two disks. 
     The stop disk  20  is rotationally driven by the screw  12 . This rotational movement continues and the stop disk  20  therefore drives therewith the mobile disk  24 . This disk is rigidly connected with the entry shaft of the reduction gear  6  which is thereby put into operation. The exit ring gear  26  is then itself also rotationally driven but with a slower rotation speed. As a numeric example, entirely illustrative and in no way limiting, the screw  12  can for example have a rotation speed of order 300 RPM. If a planetary gear train is used, the reduction gear can, for example, have a reduction ratio of 1:50. The result is then a rotation speed of the exit ring gear  26  of about 6 RPM. As indicated above in the preamble, it is appropriate to pivot the pivoting arm  2  through about 110 to 130°. The result is thus that the door is opened in about 2 to 3 seconds after the phase of lifting the door. 
     The motor  4 , or the motor with reduction gear, is advantageously subject to control by position and it is stopped once the door reaches the fully open position thereof. Additionally, the passage of current in the coil  48  is stopped sufficiently that the spring  46  by acting on the second clutch disk  42  comes to rotationally stop the screw  12 . 
     Note that during opening of the door, the pivoting arm  12  is resting on the aircraft structure through the intermediary of the edge  38  which comes to rest on the cam  32 . The pivoting arm  2  and thereby the corresponding door are therefore supported during any opening of the door thus blocking any accidental falling back down. 
     It seems unnecessary here to describe the closing procedure for the door which corresponds to the inverse procedure of the opening procedure. 
     The motorized device described here thus enables a motorization using a single motor for the phases of locking/unlocking, raising/lowering and translation of an aircraft door during the opening and closing thereof. 
     The device described can easily be controlled manually for cases especially where the electrical function is not available (e.g. electric supply outage, failure, etc.). Because of the presence of a screw/nut with bearings system, a manual maneuver becomes easier. The manual control could for example be done using a square tip crank that could be used for driving the screw of the screw/nut system. 
     The device described could also be equipped with various sensors for the control thereof. A position sensor (rotary) can also, for example, be combined with the screw of the screw/nut system—which does not necessarily use bearings—to enable better control of the door opening and closing phases. Many types of sensors can be used here. The following list is proposed as a nonlimiting example: resolver, RVDT (Rotary Variable Differential Transformer) and potentiometer. 
     The device described has all the capacity necessary in terms of performance (e.g. opening time, etc.) and availability even for meeting requirements for use in emergency opening. 
     This motorized device, as can be seen from the preceding description, serves to very substantially limit the manual force exerted by the flight crew of an aircraft for opening and closing the door. Here all the opening and closing phases are assisted by a motor. 
     The solution proposed by the present invention offers the advantage of having simple kinetics for providing all the opening/closing phases. 
     The mass of the assembly is minimized because the proposed system has good efficiencies and an optimization of the reduction ratios with which to provide motorization with an electric motor having a relatively low torque and therefore reduced mass. 
     The system can be subject to control by position and/or speed and/or torque of the door. An adaptation can be provided for example according to different opening and/or closing phases. 
     Of course, the present invention is not limited to the embodiment described above and illustrated in the drawings and to the variants indicated. It also involves any embodiment within reach of the person skilled in the art in connection with the claims here below.