Patent Publication Number: US-11396934-B2

Title: Method for maneuvering doors of bays of aircraft, and actuator used therefor

Description:
The invention relates to the manner in which doors of bays of aircraft, in particular doors closing the bays of the landing gear, are manoeuvred and held closed, but also to the manner in which the landing gear is manoeuvred and held in the retracted position in its bay. 
     TECHNOLOGICAL BACKGROUND OF THE INVENTION 
     In an aircraft whose landing gear is able to move between a deployed position and a retracted position in which it is accommodated in respective bays, there are two types of door closing said bays: doors coupled to the landing gear, which move together with said landing gear and which close again when the landing gear reaches the retracted position, and independent doors which are not coupled to the landing gear and whose movement is independent of that of the landing gear. 
     Coupled doors therefore have no need of an actuator as they are manoeuvred directly by the landing gear, whereas independent doors require a dedicated actuator. 
     In flight, the landing gear is held in the retracted position by means of a locking hook designed to latch onto an olive which is integral with the landing gear. The door or doors coupled to this landing gear are thus also held in the closed position. 
     By contrast, independent doors must be held in the closed position by dedicated locking hooks designed to latch onto olives which are integral with the independent doors. 
     It is often difficult to couple all the doors to the landing gear. Indeed, certain doors must be able to close while the landing gear is in the deployed position, so as to minimize aerodynamic perturbations caused by air entering the bay. 
     In this case, it is expedient to assign them a specific actuator and a specific locking hook, which increases the number of interfaces between the door and the structure of the aircraft, without counting the multitude of electrical or hydraulic connections for controlling the actuator and the locking hook. 
     With reference to the landing gear, it is also necessary to manoeuvre it and hold it in the retracted position, which also requires a hook for locking in the retracted position. 
     OBJECT OF THE INVENTION 
     The invention has the object of proposing a method for locking a door or a landing gear in the closed or retracted position. 
     PRESENTATION OF THE INVENTION 
     With a view to achieving this object, there is proposed a method for locking a mobile element of an aircraft, such as a door or a landing gear, the mobile element being moved between a deployed position and a closed or retracted position by means of an actuator having a sliding stem coupled to the mobile element, the stem being mounted so as to be able to slide in a body of the actuator between an extended position corresponding to the deployed position of the mobile element and a withdrawn position corresponding to the closed or retracted position of the mobile element. According to the invention, the method for locking the mobile element in the closed or retracted position comprises the step of positively blocking the sliding stem of the actuator in the withdrawn position. 
     Thus, the mobile element is locked by blocking the sliding stem of the actuator in the withdrawn position, which avoids the use of an external locking hook. 
     According to one particular embodiment of the invention, the sliding stem is blocked by means of a blocking member inside the actuator and designed to selectively block an element of a kinematic chain between a member for driving the sliding stem and the sliding stem. 
     It is to be noted that electromechanical actuators which are usually proposed for manoeuvring the doors or the landing gear generally comprise an emergency control by means of which it is possible to axially free the sliding stem such that it can slide freely, for example in the event of a failure of the motor of the actuator or seizing of the kinematic chain connecting the motor to the stem. By integrating, according to the invention, the locking of the mobile element in the closed position directly in the actuator, there is no need to provide a specific emergency control which would compensate for the failure of the internal locking, since the already-existing possibility of freeing the stem then takes its place. 
     Therefore, it is thus possible to propose an actuator/lock for a door, having an emergency function able to compensate for the failure of the manoeuvre or of the locking. 
     Preferably, the telescopic actuator for implementing the method comprises:
         a body comprising means for coupling it to a first external element;   stem mounted so as to be able to slide telescopically into the body along a sliding axis and comprising means for coupling it to a second external element;   a lead screw mounted so as to be able to rotate on the body about the sliding axis and extending within the stem to engage with a nut integral with the stem, such that a rotation of the lead screw causes the stem to slide;   means for turning the lead screw;   axial retention means for the lead screw which axially retain a bearing of the lead screw, said axial retention means being controllable so as to axially release the lead screw and thus allow the sliding stem to slide freely in the body;   a positive blocking member for selectively blocking the lead screw in rotation and thus locking the actuator in position.       

     According to one particular embodiment, the drive means of the telescopic actuator comprise:
         a shaft of non-circular cross section, preferably a splined shaft ( 7 ) mounted so as to be able to rotate on the body about the sliding axis and extending within the screw so as to turn the latter by means of a splined connection;   a motor member ( 9 ) for driving the splined shaft in rotation;
 
and in which the axial retention means ( 20 ) can be controlled so as to selectively release a bearing ( 11 ) of the lead screw.
       

    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The invention will be better understood in the light of the following description with reference to the figures of the appended drawings, in which: 
         FIG. 1  is a perspective view of a landing gear bay of an aircraft, showing one of the doors of the bay equipped with an actuator according to the invention; 
         FIG. 2  is a longitudinal section through an actuator according to one particular embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE FIGURES 
       FIG. 1  shows an aircraft landing gear  100  in the deployed position. In flight, the landing gear is normally retracted in its bay which is closed by doors  101 . The doors comprise gooseneck hinges  102  for articulating the doors on the structure of the aircraft. Each of the doors  101  is associated with an actuator  200  which will be described in detail below and which makes it possible to manoeuvre the door between an open position, shown here, and a closed position. Each actuator is coupled on one hand to the structure of the aircraft, and on the other hand to the associated door. It will be noted that the door comprises no latching olive, and that no hook is provided for latching the door when it is returned to the closed position by the actuator  200 , in accordance with the invention. 
     With reference now to  FIG. 2 , and in accordance with one particular embodiment of the invention, the actuator  200  comprises:
         a body  1  bearing, at one of its ends, a clevis  2  provided with a ball swivel for coupling to an external element, for example the structure of the aircraft, the other of the ends of the body being open;   a stem  3  mounted so as to be able to slide telescopically in the body along the sliding axis X, and bearing at its end a clevis  4  bearing a ball swivel for coupling to a second external element, in this case one of the doors  101 ;   a lead screw  5  extending inside the stem  3  and which engages therewith by a helical connection by means of a nut  6  integral with the stem  3  which forms a bearing of the stem and which is engaged on an external thread of the lead screw  5 , such that a rotation of the lead screw  5  causes the stem  3  to slide;   a shaft of non-circular cross section, for example a splined shaft  7  which extends inside the lead screw  5  and which engages therewith by a prismatic connection by means of splines  8  (shown here in part but extending over the entire length of the splined shaft  7  engaging with matching splines of the lead screw  5 ;   a motor  9  designed to drive a toothed wheel  7   a  integral with the splined shaft  7  so as to drive the latter in rotation via the intermediary of a reduction stage  9   a , said rotation of the splined shaft  7  causing the rotation of the lead screw  5 .       

     The lead screw  5  has an end  10  bearing a bearing  11  which forms the external cage of a ball bearing  12  and which is retained axially in the body  1  by retention means  20 , here of the claw type. It is to be recalled that this type of retention means comprises a hoop in which are cut claws having hook-shaped ends  23  and being able to flex radially to allow the object to be retained, in this case the bearing  11  of the lead screw  5 , to pass through. 
     In the situation shown, the bearing  11  is imprisoned by the claws  20 , the latter being prevented from flexing by means of a rotary sleeve  24  which bears on its internal face a succession of balls  25  arranged circumferentially facing the ends of the claws and separated from one another by spaces. When the sleeve  24  is placed in a first, blocking angular position (as shown here) in which the balls  25  are directly facing the ends  23  of the claws  20 , the claws  20  are prevented from flexing, and the bearing  11  is held prisoner by the claws  20 . When the sleeve  24  is placed in a second, releasing angular position in which the spaces between the balls  25  are brought back to face the ends  23  of the claws  20 , the latter can flex radially, and the bearing can, under the effect of a tensile force on the stem  3 , escape from the claws  20  to thus allow the lead screw, driven by the stem  3 , to slide. In order to make the sleeve  24  pass from the blocking position to the releasing position, the sleeve is in this case made integral with a lever  26  which is manoeuvred by an eccentric  27  which is itself actuated by a motor  28 . The rotation of the motor  28  causes the rotation of the eccentric  27 , and thus the pivoting of the lever  26  which drives the sleeve  24  in rotation. 
     In the event of an emergency, for example in the event of a failure of the motor  9  or in the event of seizing of the kinematic chain connecting the motor to the sliding stem, it is then possible, by turning the sleeve  24 , to release the bearing  11  and thus allow the lead screw  5  to move with the stem  3  under an external action (for example the landing gear pushing on the door coupled to the stem). Such an arrangement makes it possible to ensure that the stem  3  is able to slide freely even if the motor  9  is faulty or is no longer fed. 
     According to the invention, the actuator  200  is equipped with means for positively blocking the sliding stem. Here, these means comprise a wheel  30  integral with the splined shaft  7  comprising peripheral notches  31  in which a finger  32 , actuated by an electromagnet  33 , is accommodated in order to block the wheel  30  in rotation, which has the effect of angularly blocking the splined shaft, and thus axially blocking the sliding stem  3 . 
     Advantageously, when closing the door, the motor  9  is fed so as to cause the sliding stem  3  to be retracted, and thus the door to be closed. When the latter arrives in abutment, a sensor generates a signal triggering the actuation of the finger  32 . The assembly is managed such that no notch  31  is facing the finger when the door arrives in abutment. The motor  9  therefore has to carry on turning to bring the closest notch to beneath the finger  32 , which induces a prestress in the door before it is blocked in position by blocking the sliding stem  3  in the withdrawn position. 
     If at any point it proves impossible to retract the finger  32 , following a failure of the electromagnet  33 , it remains possible to order the axial retention means  20  to release the bearing  11 , making it possible for the sliding stem  3  to slide freely. The door  101  can then open, for example as a result of the thrust of the wheels of the deploying landing gear  100 . 
     The invention is not limited to that which has just been described, but rather encompasses any variant within the scope defined by the claims. In particular, although the controllable retaining member for selectively releasing the bearing from the lead screw is in this case of the claw type, other retaining members can be used, such as for example a retaining member having a retractable segment or finger. Similarly, although the member for positively blocking the sliding stem in position is in this case of the type having a finger entering into notches of a wheel, it is possible to use other types of positive blocking member, such as for example a dog. Finally, the actuator and the method of the invention also apply to manoeuvring a landing gear and holding it in the retracted position, and more generally to any mobile element of an aircraft which can move between a deployed position and a lockable retracted position.