SYSTEM FOR CONTROLLING THE MOTION SPEED OF A SLIDING DOOR AND ASSOCIATED AIRCRAFT

Description

Technical field of the invention

[0001] The invention relates to aircraft sliding door opening systems, and more particularly to systems for controlling the speed of movement of aircraft sliding doors and to aircraft equipped with at least one such system. Prior art

[0002] Generally, an aircraft includes a sliding side door designed to open during flight, for example during a parachute drop or during a helicopter hoist, when the aircraft is a helicopter.

[0003] When it is opened, the sliding door is subjected to aerodynamic forces that can generate significant opening speeds of the door.

[0004] The aerodynamic forces applied to the sliding door are proportional to the square of the aircraft's flight speed.

[0005] Generally, a helicopter is equipped with end-of-stroke shock absorbers to cushion the shock generated by the sliding door reaching its stop, thus preserving the helicopter's structure.

[0006] However, such actuators do not allow control of the speed of the sliding door during its travel, especially at the high flight speeds of the helicopter.

[0007] Documents FR3072707 and EP3747760 disclose a control device for slowing the closing of a sliding door guided by a guide rail and comprising a winder and a strap supported by the winder and connected to the door.

[0008] The guide rail includes a stop.

[0009] The winder also includes a centrifugal brake connected to the strap via a shaft so that when the sliding door opens, the centrifugal brake slows the opening speed of the sliding door by applying a resistive torque to the shaft.

[0010] The centrifugal brake consists of movable weights held radially on the drum by springs and rubbing against a metallic surface arranged around the drum to generate the resistive torque.

[0011] The resistive torque is proportional to the square of the rotational speed of the shaft and to the mass of the weights.

[0012] Because the rotational speed of the shaft is low, it is necessary to implement massive weights in the device, increasing the mass and size of said device, and reducing the aircraft's loading capacity accordingly.

[0013] In addition, if the sliding door stop is damaged or missing, the sliding door can slip off the guide rail and remain caught on the strap.

[0014] The swing of the sliding door can propel the door against the aircraft in flight, damaging the aircraft. Description of the invention

[0015] The aim of the invention is to overcome all or part of these drawbacks.

[0016] In view of the foregoing, the invention relates to a system for controlling the opening speed of a sliding aircraft door, the system comprising a mechanical door braking device, the braking device having a drive shaft and a centrifugal damper having a resistive shaft connected to the drive shaft, and connecting means intended to be connected to the sliding door and cooperating with the drive shaft so that when the sliding door moves in a predetermined direction, the connecting means drive the drive shaft and the centrifugal damper applies a resistive torque on the drive shaft to control the speed of movement of the door.

[0017] The system includes a reducer connecting the resistive shaft to the transmission shaft so that the rotational speed of the resistive shaft is greater than that of the transmission shaft when the sliding door moves in the predetermined direction.

[0018] The value of the resistive torque is proportional to the square of the rotational speed of the resistive shaft and to the mass of the weights.

[0019] The reducer amplifies the rotational speed of the resistive shaft so that for a given resistive torque value, the mass of the weights can be reduced, thereby decreasing the mass and size of the device and facilitating the integration of the system into the aircraft.

[0020] Advantageously, the centrifugal damper comprises a cylinder coated with a friction material and weights arranged inside the cylinder and connected to the resistive shaft by connecting rods so that the weights rub against the friction material under the effect of centrifugal force when the rotational speed of the resistive shaft is greater than or equal to a predetermined speed threshold.

[0021] Preferably, the braking device further includes a clutch device connecting the resistive shaft to the strap so that the clutch device is engaged when the door moves in the predetermined direction and is disengaged when the door moves in a direction other than the predetermined direction.

[0022] Advantageously, the aircraft includes a guide rail of predetermined length guiding the sliding door, the linkage means being configured to immobilize and retain the sliding door in the guide rail when the stroke of said door in the predetermined direction is greater than the length of the rail.

[0023] Preferably, the aircraft includes a guide rail of predetermined length guiding the sliding door, the linkage means being configured to release the sliding door when the stroke of said door in the predetermined direction is greater than the length of the rail.

[0024] Advantageously, the connecting means include a strap, the braking device further includes a winding mechanism configured to wind the strap around the drive shaft when the door moves in a direction other than the predetermined direction.

[0025] Preferably, the system includes a winding drum supporting the strap, the drum being connected to the drive shaft.

[0026] Advantageously, the length of the strap stretched between the door and the drive shaft is less than the length of the rail.

[0027] Preferably, the strap and the drum include means for disengaging the strap from the sliding door or the drive shaft when the stroke of said door in the predetermined direction is greater than the length of the rail.

[0028] Also proposed is an aircraft with a sliding door and a system as defined above connected to the sliding door. Brief description of the drawings

[0029] Other objects, features and advantages of the invention will become apparent from the following description, given solely by way of non-limiting example, and made with reference to the accompanying drawings in which: [ Fig 1 ] schematically illustrates an aircraft comprising a sliding door according to the invention; [ Fig 2 ] schematically illustrates a partial view of the aircraft comprising a system for controlling the opening speed of the sliding door according to the invention; [ Fig 3 ] schematically illustrates a partial view of the interior of the aircraft cabin according to the invention; [ Fig 4 ] schematically illustrates an example of a system for controlling the opening speed of the sliding door according to the invention; [ Fig 5 ] schematically illustrates an example of an embodiment of a clutch device according to the invention, and [ Fig 6 ] ] Fig 7 ] ] Fig 8] schematically illustrate an example of connection means according to the invention. Detailed description of at least one embodiment

[0030] We refer to the figure 1 which schematically illustrates an aircraft 1 comprising a sliding door 2, shown in the closed position, and designed to open in flight, a guide rail (not shown) guiding the sliding door 2, and a system 4 for controlling the speed of movement of the sliding door 2 (not shown).

[0031] The normal direction of movement of the aircraft is represented by a forward-pointing arrow (FWD). The door, however, opens to the rear and is therefore subject to the aerodynamic forces generated during the movement of aircraft 1.

[0032] It is assumed that system 4 controls the opening speed of sliding door 2.

[0033] Alternatively, system 4 controls the closing speed of sliding door 2.

[0034] Aircraft 1 as depicted is a helicopter.

[0035] Of course, aircraft 1 can be any type of aircraft with a sliding door designed to open in flight, for example an airplane with a sliding door.

[0036] There figure 2 illustrates a partial view of aircraft 1, from the outside, with the sliding door 2 open and engaged in the guide rail 3.

[0037] Sliding door 2 is supported against a stop (not shown) of guide rail 3.

[0038] The sliding door 2 speed control system 4 (shown in dotted line) is located in the aircraft cabin 1.

[0039] There figure 3 illustrates a partial view of the interior of the cabin of aircraft 1, with the sliding door 2 closed.

[0040] The control system 4 includes a mechanical braking device 5 to limit the speed of movement of the sliding door 2 and mounted on the structure of the aircraft cabin 1, and connecting means comprising a strap 6 wound in the device 5 and attached to a fixing point 7 of the sliding door 2.

[0041] The braking device 5 here limits the opening speed of the sliding door 2.

[0042] Alternatively, the braking device 5 can be mounted on the sliding door 2, and the strap 6 is attached to a fixing point on the aircraft cabin structure 1.

[0043] The connecting means can further immobilize and retain the sliding door 2 in the guide rail 3 when the stroke of the sliding door 2 is greater than the length of the guide rail to prevent the sliding door 2 from coming out of the guide rail 3 and damaging the aircraft 1.

[0044] The connecting means prevent the sliding door 2 from coming off the guide rail 3 when the stop of the guide rail 3 is damaged or non-existent so as to prevent the sliding door 2 held by the connecting means alone from damaging the aircraft 1.

[0045] Alternatively, the linking means release the sliding door 2 when the stroke of the sliding door 2 is greater than the length of the guide rail.

[0046] Since the trajectory of the sliding door 2 is dependent on the geometric characteristics of the sliding door 2, the aircraft 1 and the guide rail 3, the trajectory can be predetermined and optimized so as to expel the sliding door 2 from the aircraft 1 in flight without hitting a sensitive part of the aircraft 1 allowing the flight to continue safely.

[0047] The system 4 can be mounted on either side of the aircraft 1 relative to a longitudinal axis of symmetry of the aircraft 1, depending on the position of the door.

[0048] When the sliding door 2 opens, the strap 6 unfolds and lengthens under the effect of the translation of the sliding door 2.

[0049] According to another embodiment, the linking means include a rack fixed to the sliding door 2 and the device 5 includes a pinion cooperating with the rack.

[0050] According to yet another embodiment, the linking means comprise a belt connected on one side to the device 5 and, on the other side, to a pulley attached to the sliding door 2.

[0051] There figure 4 illustrates an example of the implementation of system 4.

[0052] We find the braking device 5 and the strap 7.

[0053] The braking device 5 includes a housing 8 comprising a transmission shaft 9 with a central axis A held in rotation in the housing 7 by bearings 12, for example ball bearings, and a passage 30 allowing the strap 6 to pass through the housing 8. Of course, the bearings 10 can be of another type, for example roller bearings or plain bearings.

[0054] The braking device 5 further includes a winding drum 11 supporting the strap 6 and held in rotation in the casing 8 by the bearings 12.

[0055] The drum 11 is connected to a first end of the transmission shaft 9 via a clutch device 13.

[0056] Device 5 also includes a reducer 14.

[0057] The clutch device 13 is engaged when the strap 6 is unwound so that the strap 6 drives the transmission shaft 9, and disengaged when the strap 6 is wound up when the sliding door 2 closes, facilitating the winding of the strap 6.

[0058] Alternatively, device 5 does not include clutch device 13, the transmission shaft 9 being driven by the belt 6 when it is wound around the drum 11.

[0059] The clutch device 13 includes, for example, a freewheel 15 as shown in the figure 5 .

[0060] The freewheel 15 includes, for example, pawls 16 cooperating with notches 17 so that when the strap 6 is unwound, the pawls 16 are engaged in the notches 17, and so that when the strap 6 is wound around the drive shaft 9 (closing the sliding door 2), the pawls 16 are no longer engaged in the notches 17.

[0061] The pawls 16 are arranged on the drum 11, and the notches 17 are arranged on the transmission shaft 9.

[0062] Alternatively, the clutch device 13 includes a roller freewheel.

[0063] The second end of the transmission shaft 9 is connected to a centrifugal damper 19 via the reducer 14.

[0064] The reducer 14 includes an input 20 connected to the transmission shaft 9 and an output 21 connected to a resistive shaft 22 of the centrifugal damper 19.

[0065] The resistive shaft 22 is held in rotation within the housing 7 by bearings 10, for example ball bearings. Of course, the bearings 10 can be of another type, for example roller bearings or plain bearings.

[0066] When the sliding door 2 opens, the centrifugal damper 19 applies a resistive torque Cr to the drive shaft 9 via the resistive shaft 22 to control the speed of movement of the sliding door 2.

[0067] The centrifugal damper 19 comprises a cylinder 23 coated with a friction material and weights 24 arranged inside the cylinder and connected to the resistive shaft 22 by connecting rods 25.

[0068] Cylinder 23 is fixed in on the crankcase 8.

[0069] When the rotational speed of the resistive shaft 22 is greater than or equal to a predetermined speed threshold, under the effect of centrifugal force, the weights 24 movable relative to the resistive shaft 22 rub against the friction material generating the resistive torque Cr proportional to the square of the rotational speed of the resistive shaft 22.

[0070] The speed threshold allows the opening speed of the sliding door 2 to be optimized at low speed (below the speed threshold) by defining a resistive torque Cr of zero.

[0071] The reducer 14 is dimensioned so that the rotational speed of the resistive shaft 22 is greater than that of the transmission shaft 9 when the sliding door 2 opens and includes, for example, an epicyclic reducer.

[0072] The reducer 14 allows the rotational speed of the resistive shaft 22 of the centrifugal damper 19 to be amplified, the rotational speed of the resistive shaft 22 being equal to the rotational speed of the transmission shaft 9 multiplied by the ratio of the reducer 14.

[0073] Since the value of the resistive torque Cr is proportional to the square of the rotational speed of the resistive shaft 22 and to the mass of the weights 24, and since the reducer 14 amplifies the rotational speed of the resistive shaft 22, for a given value of resistive torque Cr, the mass of the weights 24 can be reduced compared to weights of a known prior art braking device, thereby reducing the mass and size of the device 5 and facilitating the integration of the system 4 into the aircraft 1.

[0074] Device 4 may further include a winding mechanism 26 ( figure 4) to wrap the strap 6 around the drive shaft 9 when the sliding door 2 closes.

[0075] The winding mechanism 26 includes, for example, a constant force spiral spring cassette.

[0076] When the device 4 is equipped with the clutch device 13, the reducer 14 and the centrifugal damper 19 are disengaged from the drum 11 facilitating the winding of the strap 6 around the drum 11.

[0077] The length of the strap 6 stretched between the sliding door 2 and the drive shaft 9 can be chosen to be less than the length of the guide rail 3 so that the strap 6 immobilizes and holds the sliding door 2 when the stroke of the sliding door 2 is greater than the length of the guide rail 3 to prevent the sliding door 2 from coming off the guide rail 3 and damaging the aircraft 1 under the effect of the swing projecting the sliding door 2 held by the only strap 6 against the aircraft 1.

[0078] Alternatively, the strap 6 is fixed so that it detaches from the sliding door 2 or the drive shaft 9 when the stroke of said door 2 is greater than the length of the guide rail 3.

[0079] The strap 6 releases the sliding door 2 when the stroke of the sliding door 2 is greater than the length of the guide rail 3.

[0080] THE figures 6, 7 and 8illustrate an example of linkage means releasing the sliding door 2 when the stroke of the sliding door is greater than the length of the guide rail 3 not having a stop, the strap 6 detaching from the drum 11 and the transmission shaft 9.

[0081] The strap 6 has a protrusion 27 and is wrapped with one or more guard turns around the drum 11 having an opening 28 so that the protrusion 27 inserted into the opening 26 keeps the strap 6 attached to the drum 11.

[0082] When the sliding door 2 is in contact with and held by the stop of the guide rail 3, the strap 6 is held on the drum as shown in the figure 6 .

[0083] When the stop on the guide rail 3 is non-existent or unable to hold the sliding door 2, the strap 6 unwinds completely ( figure 7) and is held on the drum by the protrusion 27 inserted into the opening 26.

[0084] When the opening 28 is opposite the passage 30 of the housing 8, the protrusion 27 escapes from the opening 28 so that the strap 6 escapes from the device 4.

[0085] The outgrowth 27 cooperating with the opening 26 form means of disengagement.

Claims

1. System (4) for controlling the speed of opening of a sliding door (2) for an aircraft (1), the system (4) comprising a mechanical braking device (5) for the door, the mechanical braking device (5) having a transmission shaft (9) and a centrifugal damper (19) having a resistance shaft (22) connected to the transmission shaft, and linking means (6) that are designed to be connected to the sliding door and cooperating with the transmission shaft so that, when the sliding door moves in a predetermined direction, the linking means drive the transmission shaft and the centrifugal damper applies a resistance torque to the transmission shaft in order to control the speed of movement of the door, characterized in that the system comprises a speed reducer (14) connecting the resistance shaft to the transmission shaft so that the speed of rotation of the resistance shaft is greater than that of the transmission shaft when the sliding door moves in the predetermined direction.

2. System according to claim 1, wherein the centrifugal absorber (19) comprises a cylinder (23) coated with a friction material and flyweights (24) disposed inside the cylinder and connected to the resistance shaft (22) by connecting links (25) so that the flyweights rub against the friction material under the effect of the centrifugal force when the speed of rotation of the resistance shaft is greater than or equal to a predetermined speed threshold.

3. System according to one of claims 1 or 2, wherein the braking device (5) further comprises a clutching device (13) connecting the resistance shaft (22) to the belt (6) so that the clutching device is clutched when the door (2) moves in the predetermined direction and is declutched when the door moves in a direction other than the predetermined direction.

4. System according to one of claims 1 to 3, the aircraft (1) having a guide rail (3) of predetermined length guiding the sliding door (2), the linking means (6) being configured to immobilize and retain the sliding door in the guide rail when the travel of said door in the predetermined direction is longer than the length of the rail.

5. System according to one of claims 1 to 3, the aircraft (1) having a guide rail (3) of predetermined length guiding the sliding door (2), the linking means being configured to release the sliding door when the travel of said door in the predetermined direction is longer than the length of the rail.

6. System according to one of claims 1 to 5, wherein the linking means comprise a belt (6), the braking device (5) further comprising a winding mechanism (26) configured to wind the belt around the transmission shaft (9) when the door moves in a direction other than the predetermined direction.

7. System according to claim 6, having a winding drum (11) supporting the belt (6), the drum being connected to the transmission shaft (9).

8. System according to one of claims 6 or 7 dependent on claim 4, wherein the length of the belt (6) tensioned between the door (2) and the transmission shaft (9) is shorter than the length of the rail (3).

9. System according to one of claims 6 or 7 dependent on claim 5, wherein the belt (6) and the drum comprise separation means for separating the belt (6) from the sliding door (2) or from the transmission shaft (9) when the travel of said door in the predetermined direction is longer than the length of the rail.

10. Aircraft comprising a sliding door and a system (3) according to one of claims 1 to 9 connected to the sliding door (2).