Pivoting landing gear provided with an immobilization system

Abstract

The present invention relates to a landing gear (10) having a pivoting assembly (12) that supports a stand (11) and a contact member (15) and can rotate about a pivot axis (AXP) with respect to the stand (11). A fixed system (20) includes a movable pin (25) and a passage (22) provided in a base (21) fixed to the pivoting assembly. An elastic locking system (40) tends to press the pin (25) into the passage (22) in a locking mode. An elastic unlocking system (50) is configured to move the pin (25) out of the passage (22) when the activation of the unlocking mode is commanded by a control device (30), and the elastic unlocking system (50) is corrected so that the pin (25) can be extracted from the passage (22) only when there is a shear force between the base (21) and the pin (25) that is smaller than a threshold value.

Description

Technology Field

[0001] This application claims priority to FR 23 07363 filed on July 10, 2023, the entire disclosure of which is incorporated herein by reference.

[0002] The present invention relates to a pivot-type landing gear equipped with a fixed system.

[0003] The landing gear of an aircraft, for example, a rotary-wing aircraft or a helicopter, may include at least one pivoting landing gear. Such pivoting landing gear may include an assembly capable of pivoting 360 degrees around a pivot axis to carry at least one ground contact member and facilitate movement of the aircraft on the ground. Hereinafter, "ground" refers to any surface on which an aircraft can land, such as the surface of the earth, the roof of a building, the deck of a ship, etc.

[0004] For example, a three-wheeled rotary-wing aircraft may include two main landing gears and one auxiliary landing gear, each comprising at least one wheel. The two main landing gears cannot pivot. However, the auxiliary landing gear may pivot to ensure the aircraft's maneuverability on the ground. When on the ground, the wheels or wheels of the auxiliary landing gear may pivot freely around a pivot axis distinct from the wheel's axis of rotation. For example, in a helicopter equipped with a yaw angle control system of the type including a rear rotor, turning on the ground can be performed by controlling the thrust applied by this yaw angle control system. The yaw angle control system generates a moment on the aircraft airframe supported by the landing gear, and this moment automatically pivots the auxiliary landing gear to orient the aircraft in the required direction.

[0005] However, these pivot-type landing gears are typically provided with a locking system. Upon command, the locking system locks the rotary landing gear to a position where the aircraft can move in a straight line. In practice, it is necessary to retractably lock the auxiliary landing gear during a landing due to engine failure or when landing the aircraft on an incline, a ship's deck, or an equivalent location.

[0006] The disclosed fixing system includes a pin that can enter the bore of a base fixed to the pivoting assembly of a pivoting landing gear. The fixing system also includes an elastic connecting rod connected to the pin and a control device. The control device may include a handle connected to the elastic connecting rod by a non-elastic link.

[0007] To place the fixed system in unlock mode, the operator operates the control device to position the elastic connecting rod in the first position. The locking pin is located outside the bore. As a result, the pivoting assembly pivots freely around the pivot axis.

[0008] To lock the pivot landing gear, the operator manipulates the control device to position the elastic connecting rod in a second position, bringing it closer to the bore.

[0009] When the pin aligns with the bore, the pin enters the bore. Then, the fixed system is in the locking stage of the locking mode. Subsequently, the pivoting assembly can no longer pivot freely 360 degrees around the pivot axis.

[0010] If the pin does not align with the bore, it comes into contact with the base. The elastic connecting rod is compressed and tends to push the pin toward the base. Subsequently, the fixing system enters the armed phase of the locking mode. The pivoting assembly can temporarily pivot freely around the pivot axis. As soon as the pin reaches the bore, the elastic connecting rod expands and presses the pin into the bore. Consequently, the fixing system automatically switches to the locked phase of the locking mode.

[0011] Another known fixed system includes a pin capable of rotational movement rather than translational movement.

[0012] This locking system is useful. However, when the pivoting assembly is in the locked position and tends to pivot, the base applies a shear force to the locking pin. Depending on the strength of this force and the coefficient of friction between the pin and the base, unlocking may be impossible. In particular, if the yaw control system generates significant lateral thrust, the shear force can be substantial. However, if the pilot forcibly moves the control unit to unlock the locking system, there is a possibility that the aircraft will suddenly become unstable. Background Technology

[0013] Patent document US 3375999 A describes a releaseable locking mechanism for a pivot wheel. This mechanism includes a protrusion that can be received in a notch between two locking arms. The wheel is locked in a stationary state, and the lock is released when a force exceeds a threshold value. Therefore, this system is not designed to address the current problem.

[0014] Patent document WO 2010115893 A1 describes a system comprising a friction member for applying a frictional force between two components. The system includes a control means for changing a pre-load applied to the friction member by a pressurizing member.

[0015] Patent document EP 662906 B1 describes a means for rotatably locking a landing gear provided with a locking pin assembly.

[0016] Patent document CN 104210654 A describes a wheel lock indicator comprising a pin capable of translational movement relative to a housing and automatically fixed in place by means of a return spring.

[0017] Patent document US 2502522 A describes a landing gear provided with a pivoting assembly that supports a stand and a contact member. The landing gear has a fixing system comprising a pin and a passage provided in the stand. Furthermore, the elastic system includes two springs. A first spring is positioned between an upper plate fixed to the pivoting assembly and a collar fixed to the pin, while a second spring is positioned between a lower plate fixed to the pivoting assembly and a collar.

[0018] Patent document US 2384054 A describes a retractable landing gear provided with a system including a cable passing around a pulley to connect a centering pin.

[0019] Patent document GB 970425 A describes a landing gear provided with a latch that can engage with an opening of a fork that supports a wheel. means of solving the problem

[0020] Purpose and Overview of the Invention

[0021] Therefore, the objective of the present invention is to provide a landing gear that is provided with an innovative fixing system to limit the risk of sudden instability.

[0022] The present invention relates to a landing gear having a pivoting assembly that supports a contact member configured to contact a stand and a ground, wherein the pivoting assembly can rotate about a pivot axis with respect to the stand, and the landing gear has a fixed system comprising a movable pin and a control device configured to request the application of a locking mode or an unlocking mode, the fixed system comprises a passage provided in a base fixed to the pivoting assembly, the pin is outside the passage during the unlocking phase of the unlocking mode, and the pin can move in the passage at an azimuth with respect to the pivot axis during the locking phase of the locking mode, and the fixed system has an elastic locking system that tends to press the pin into the passage in the locking mode, and the pin is pushed into the passage in the locking mode against the base during the preparation phase of the locking mode or as soon as the pin becomes aligned with the passage in the locking phase by the elastic locking system, unless the pin enters the passage.

[0023] The fixing system includes an elastic unlocking system configured to move the pin out of the passage when the activation of the unlocking mode is commanded by a control device, and the elastic unlocking system is calibrated so that the pin can be extracted from the passage only when there is a shear force between the base and the pin that is smaller than a threshold value.

[0024] Accordingly, the fixing system is configured to fix the pivoting assembly within a predetermined position range regarding the stand during the locking phase of the locking mode, and to allow unlimited pivoting of the pivoting assembly relative to the stand during the unlocking phase of the unlocking mode.

[0025] The expression "fixing system configured to fix the pivoting assembly within a predetermined positional range with respect to the stand during the locking phase of the locking mode" implies that when the pin is in the passage, the pivoting assembly can pivot only within the azimuth space between the stand and the pin with respect to the pivot axis. In practice, the passage has dimensions along an arc larger than the dimensions of the pin with respect to the pivot axis. Therefore, the pin can easily enter the passage, but the base has limited freedom of movement in terms of azimuth. Depending on the position of the pin in the passage, the base may or may not apply shear force to the pin.

[0026] The expression “the pin may move in the passage at an azimuth with respect to the pivot axis” means that there is always a gap separating the pin from the base along a circle centered on the pivot axis. This gap provides freedom of movement of the base relative to the pin when the pin is in the passage, and is limited to a predetermined positional range, for example, of about 0.5 degrees. In an aircraft, this angle may vary depending on the longitudinal distance between the aircraft’s fixed landing gear and the landing gear having the pivoting assembly of the present invention.

[0027] In addition to the preparation, locking, and unlocking steps of the conventional technology, the elastic unlocking system enables the generation of an unlocking preparation step when switching from a locking mode to an unlocking mode.

[0028] When the base applies a shear force to the pin that is smaller than the threshold value, the pin moves directly out of the passage, and the fixing system directly switches to the unlocking stage. The pivoting assembly can freely pivot around the pivot axis, for example, at least 180 degrees, and actually more than 360 degrees.

[0029] If the base applies a shear force greater than or equal to the pin's threshold, for example, if there is a rear rotor generating a significant yaw moment in the aircraft airframe, switching from lock mode to unlock mode causes the elastic unlock system to compress. The fixed system transitions to the release preparation phase of the unlock mode. This elastic unlock system is corrected so that it cannot expand under these conditions. That is, the stiffness along the compression / expansion axis of the elastic unlock system is selected to ensure the transition to the unlock phase under desired conditions. As soon as the shear force drops below the threshold, the pivoting assembly pivots slightly, the elastic unlock system expands, and the pin is automatically ejected from the passage to reach the unlock phase.

[0030] Therefore, the elastic unlocking system prevents unlocking when there is a large shear force, which is synonymous with a large moment applied to the airframe of a helicopter. This elastic unlocking system prevents sudden movement when the pilot issues a command to activate the unlock mode. This means that the landing gear can be unlocked only under specific operating conditions. If the shear force is large, unlocking is prohibited even if the pilot issues a command. Therefore, the pilot can issue an unlock command regardless of the shear stress on the pin. Unlocking is applied only when the force applied to this pin falls below a predetermined force threshold. Therefore, the pivoting landing gear according to the present invention helps optimize safety.

[0031] The landing gear according to the present invention may have one or more of the following features individually or in combination.

[0032] According to the first alternative, the pin can be translated relative to the base along a translation axis parallel to the pivot axis, for example.

[0033] Therefore, the first alternative is applicable to a system including a pin capable of translational movement.

[0034] For example, the fixing system may include a hollow support extending toward a base from an end wall to an open end along a translational axis, said open end being positioned between the end wall and the base, and a pin including a head fixed to a locking rod, the head being positioned in the hollow support, the locking rod exiting through the open end of the hollow support at least in a locking stage, and an elastic locking system being positioned between the end wall and the head.

[0035] The support guides the translational movement of the head and the pin accordingly. The stand may also guide the translational movement of the pin.

[0036] Therefore, when the pin does not align with the passage, the elastic locking system may be compressed when switching from unlock mode to lock mode. The fixing system is in the preparation phase, and the elastic locking system is ready to expand to press the pin into the passage.

[0037] The elastic locking system may include a locking spring having a coil fixed to the end wall.

[0038] According to the first variation of the first alternative, the support can be translated relative to the stand, and the control device is connected to the support.

[0039] During the transition from unlock mode to lock mode, the support moves from a first position to a second position. If the pin does not align with the passage, the support compresses the elastic locking system during a possible preparation phase. Then, the pin is pressed against the support. As soon as the pin is aligned with the passage, the elastic locking system expands and automatically transitions to the locking phase as quickly as possible.

[0040] During the transition from lock mode to unlock mode, the support transitions from the second position to the first position. If the base applies a shear force greater than or equal to the pin's threshold, the pin remains in place, and the support compresses the elastic unlock system during a possible disarmed phase. As soon as the pin's shear force drops below the threshold, the elastic unlock system expands and automatically transitions to the unlock phase.

[0041] Therefore, the first variation of the first alternative can be relatively simple and easy to implement.

[0042] The elastic unlocking system can be positioned between the head and the inner shoulder of the support, the locking rod passes through the inner shoulder, and the inner shoulder is located between the head and the base.

[0043] The elastic unlocking system may include an unlocking spring having a coil fixed to an inner shoulder.

[0044] According to the second variation of the first alternative, the support can be fixed to a stand, and the pin includes an entry rod fixed to the head and passing through the end wall of the support.

[0045] For example, the entry rod extends from a head fixed to the hollow tube to the top, and the control device extends to a plate capable of translational movement within the hollow tube and includes a cable passing through the wall of the tube, and an elastic unlocking system is positioned between the wall and the plate.

[0046] Furthermore, the stiffness of the elastic unlocking system along the translational axis can be greater than the stiffness of the elastic locking system along the translational axis. Therefore, when the pin is released from the base, the elastic unlocking system expands.

[0047] A second variation of the first alternative can also be relatively simple and easy to implement.

[0048] Furthermore, the stiffness of the elastic unlocking system along the translational axis may be greater than the stiffness of the elastic locking system along the translational axis, but this is not the case, particularly according to the second variation of the first alternative. Therefore, when the pin is released from the base, the elastic unlocking system expands.

[0049] According to the second alternative, the pin does not have translational degrees of freedom but has rotational degrees of freedom relative to the stand.

[0050] For example, a pin may be supported by a lever pivotably connected to a stand, an elastic locking system is positioned between the stand and the lever, a control unit includes a cable connected to a panel that can translate along a guide, the guide is connected to the lever, and an elastic unlocking system is positioned between a partition of the guide through which the cable passes and the panel.

[0051] Regardless of the alternative, the contact member may include a wheel capable of rotating about a wheel axis with respect to the pivoting assembly, said wheel axis being separate from the pivot axis. The wheel axis and the pivot axis are also not parallel.

[0052] According to another purpose, the rotary-wing aircraft may include at least one pivot-type landing gear according to the present invention.

[0053] The present invention relates to a method for locking and unlocking a landing gear, namely, a pivoting assembly comprising a contact member configured to contact a stand and a ground, wherein the pivoting assembly can rotate about a pivot axis with respect to the stand, and the landing gear has a fixing system configured to fix the pivoting assembly within a predetermined positional range with respect to the stand during the locking phase of a locking mode and to allow unlimited pivoting of the pivoting assembly with respect to the stand during the unlocking phase of an unlocking mode, wherein the fixing system includes a movable pin and a control device configured to request the application of a locking mode or an unlocking mode, and wherein the fixing system includes a passage provided in a stand fixed to the pivoting assembly, wherein the pin is outside the passage during the unlocking phase and the pin can move within the passage at an azimuth with respect to the pivot axis during the locking phase.

[0054] The above method includes the following steps:

[0055] When the fixed system (20) is in unlock mode, the control device is activated to switch to lock mode, and then (i) if the pin aligns with the passage, the pin is moved into the passage; and (ii) if the pin does not align with the passage, the pin is compressed against the base using an elastic locking system, and as soon as the pin aligns with the passage, the pin is moved into the passage; and

[0056] When the fixed system is in lock mode, the control device is activated to switch to unlock mode, and then, when the pin is in the passage and in contact with the base, the elastic unlock system is compressed, and (i) a step of maintaining the pin in the passage as long as the pin receives a shear force greater than a threshold, wherein the fixed system is in the release preparation stage; and (ii) a step of expanding the elastic unlock system and discharging the pin outside the passage due to the expansion effect as soon as the pin receives a shear force less than a threshold. Brief explanation of the drawing

[0057] The present invention and its advantages are further explained in the context of the following description of the given embodiments through examples and with reference to the accompanying drawings. FIG. 1 is a diagram illustrating a rotary wing aircraft according to the present invention. Figure 2 is a diagram illustrating a plan view of the rotary-wing aircraft of Figure 1. FIG. 3 is a diagram illustrating a pivotal landing gear according to the present invention having a fixed system in the locking stage of a locking mode. Figure 4 is a diagram illustrating the fixing system of the pivot-type landing gear of Figure 3 during the release preparation stage of the unlock mode. Figure 5 is a diagram illustrating the fixing system of the pivot-type landing gear of Figure 3 during the unlocking stage of the unlock mode. Figure 6 is a diagram illustrating the fixing system of the pivot-type landing gear of Figure 3 during the preparation stage for unlocking the lock mode. Figure 7 is a diagram illustrating a fixed system in the locking stage of a locking mode. Fig. 8 is a diagram illustrating the fixed system of Fig. 7 during the unlock preparation stage of the unlock mode. Fig. 9 is a diagram illustrating the fixed system of Fig. 7 in the unlocking step of the unlock mode. Figure 10 is a diagram illustrating the fixed system of Figure 7 in the preparation stage of the lock mode. Figure 11 is a diagram illustrating a fixed system in the locking stage of a locking mode. Figure 12 is a diagram illustrating the base of the fixed system of Figure 11. FIG. 13 is a diagram illustrating the fixed system of FIG. 11 during the unlock preparation stage of the unlock mode. FIG. 14 is a diagram illustrating the fixed system of FIG. 11 in the unlocking step of the unlock mode. Fig. 15 is a diagram illustrating the fixed system of Fig. 11 in the preparation stage of the lock mode. Specific details for implementing the invention

[0058] Elements existing in two or more drawings are provided with the same reference numeral in each drawing.

[0059] FIG. 1 illustrates a rotary-wing aircraft (1) according to the present invention. The rotary-wing aircraft (1) comprises a body (2) capable of carrying at least one rotor and a yaw control system. In this case, the illustrated rotary-wing aircraft (1) includes a main rotor (4) and a rear rotor (5) that act as a yaw control system.

[0060] Additionally, the aircraft (2) is placed on a landing system (6) that includes, for example, at least one landing gear (7), i.e., in this example, two main landing gears (7) and an auxiliary landing gear (8).

[0061] Such rotary-wing aircraft (1) includes, in particular, at least one pivotal landing gear (10), i.e., in this example, an auxiliary landing gear (8).

[0062] Referring to FIG. 2, when the yaw control system applies lateral thrust (F1), the pivot landing gear (10) rotates on the ground around the pivot axis (AXP) to correct the direction of the rotary-wing aircraft (1).

[0063] Therefore, the landing gear (10) includes a fixing system for maintaining a pivoted landing gear (10) substantially aligned along the forward movement axis of the rotary-wing aircraft (1) under specific conditions.

[0064] FIG. 3 illustrates an embodiment of a pivoting landing gear (10) according to the present invention. Regardless of the embodiment, the landing gear (10) is provided with a stand (11) connected to the aircraft (2) and a pivoting assembly (12) capable of pivoting about a pivot axis (AXP) with respect to the stand (11). The pivoting assembly (12) supports at least one contact member (15) configured to contact the ground (100). For example, the contact member (15) includes a skid and / or wheel (150) capable of rotating about a wheel axis (AXROT) with respect to the pivoting assembly (12).

[0065] As an example, FIG. 3 illustrates an example of a stand (11) and a pivoting assembly (12), but other embodiments of the pivoting assembly (12) may be considered. In particular, the stand (11) may be fixed or housed without departing from the scope of the present invention. According to the illustrated example, the pivoting assembly (12) may include a cylinder (13) that can rotate about a pivot axis relative to the stand (11). Furthermore, the pivoting assembly (12) may include a damper (14) that is supported by the cylinder (13) and at least partially housed within the cylinder (13), and the damper (14) may be provided with a device referred to as an anti-shake device. Additionally, scissors (16) are hinge-connected to the cylinder (13) and the damper (14). For example, at least one contact member (15) may be supported by the scissors (16) or the damper (14).

[0066] Regardless of the embodiment of the pivoting assembly (12) and the stand (11), the landing gear (10) includes a fixing system (20) configured to perform the following operations: (i) fixing the pivoting assembly (12) within a predetermined limited position range with respect to the stand (11) during the locking phase of the locking mode; and (ii) allowing unlimited pivoting of the pivoting assembly (12) with respect to the stand (11) during the unlocking phase of the unlocking mode.

[0067] FIG. 3 illustrates a first version of a first alternative shown in more detail in FIGS. 4 to 6, but other embodiments can be seen in FIGS. 7 to 15.

[0068] Regardless of the embodiment, the fixed system (20) comprises a pin (25) movable in relation to the pivoting assembly (12) and a control device (30) configured to request the application of a lock mode or an unlock mode. Each mode may include two steps as described below. For example, the control device (30) may include at least one cable (33) movable in translation, at least one bell crank, etc. The term “cable” means, for example, an elongated link that is inelastic and / or advantageously received in a protective sheath.

[0069] The fixed system (20) further includes a passage (22) provided in a base (21) fixed to the pivoting assembly (12). For example, the base (21) forms an integral component with the cylinder (13) according to FIG. 3.

[0070] Accordingly, the pin (25) is outside the passage (22) during the unlocking phase of the unlocking mode, thereby providing the pivoting assembly (12) with complete freedom of rotational movement around the pivot axis (AXP).

[0071] Conversely, the pin (25) is placed in the passage (22) during the locking phase of the locking mode illustrated in FIG. 3 to prevent the pivoting assembly (12) from rotating around the pivot axis (AXP). Then, the rotational movement freedom of the pivoting assembly around the pivot axis (AXP) is limited by the operating interval. Then, the pin (25) can move slightly within the passage (22) at an azimuth with respect to the pivot axis (AXP).

[0072] Furthermore, the fixed system (20) has an elastic locking system (40) which is indirectly activated by a control device (30) during the locking mode and tends to press a pin (25) into the passage (22) during this locking mode. Thus, starting from the unlocking mode, the method of the present invention includes the step of activating the control device (30) to switch to the locking mode, and then moving the pin (25) into the passage (22) when the pin (25) is aligned with the passage (22) to reach a locked state. When the pin (25) is not aligned with the passage (22), the elastic locking system (40) compresses the pin (25) against the base (21) during the preparation step, and then moves the pin (25) into the passage (22) as soon as the pin (25) is aligned with the passage (22).

[0073] Furthermore, the fixed system (20) includes an elastic unlocking system (50) that is indirectly activated by a control device (30) during an unlocking mode to release the pivoting assembly (12) by causing the pin (25) to exit the passage (22). The elastic unlocking system (50) is configured so that the pin (25) can be extracted from the passage (22) only when there is a shear force less than a threshold between the base (21) and the pin (25). Thus, starting from a locking mode, the method of the present invention includes the step of activating the control device (30) to switch to an unlocking mode, and compressing the elastic unlocking system (50) during the release preparation step when the pin (25) is in the passage (22) and in contact with the base (21). As long as the pin (25) receives a shear force greater than a threshold, the pin (25) is maintained within the passage (22). However, as soon as the pin (25) receives a shear force smaller than the threshold value, the elastic unlocking system (50) expands the pin (25) to switch to an unlocked state and discharges it outside the passage (22).

[0074] According to the first alternative of FIGS. 3 to 10, the pin (25) may translate relative to the base (21) along a translation axis (AXT) parallel to the pivot axis (AXP), for example. The passage (22) may be a bore of the base (21).

[0075] Accordingly, the fixed system (20) includes a hollow support (60). This support (60) includes a tubular guide extending toward the base (21) from the end wall (61) of this support (60) to the open end (62) of this support (60) along the translational axis (AXT). Consequently, the open end (62) is located between the end wall (61) and the base (21) along the translational axis (AXT).

[0076] The pin (25) partially extends into the support (60) at least during the fixed phase. Regardless of the first alternative variation, the pin (25) includes a head (26) that slides within the support (60) guided by a tubular guide. Furthermore, the pin (25) includes a locking rod (27) that is fixed to the head and consequently connected to the head. This locking rod (27) appears through the open end (62) of the support (60) at least during the locking phase and can enter the passage (22) of the base (21). For safety, the locking rod (27) may include a weak-link area (270). The locking rod (27) may also be guided by a guide fixed to the base.

[0077] Under these conditions, the elastic locking system (40) is positioned between the end wall (61) and the head (26). The elastic locking system (40) may be fixed to the end wall (61). For example, the elastic locking system (40) may include an elastic block or locking spring (41) having a coil (42) fixed to the end wall (61) in a conventional manner.

[0078] According to the first variation of the first alternative of FIG. 3, the support (60) can be translated along the translation axis (AXT) relative to the base (21). For example, the support (60) slides within a guide fixed to the stand (11).

[0079] A control device (30) is connected to the support (60) to move the support from a first position (POS1) requesting the application of an unlock mode to a second position (POS2) requesting the application of a lock mode. For example, the control device (30) includes a handle (31) or equivalent, or actually a linear actuator, etc., connected to the support (60) and, for example, an end wall (61) by a cable (33). The cable (33) can slide within a rigid outer sheath (32).

[0080] Additionally, the elastic unlocking system (50) is positioned between the head (26) and the inner shoulder (63) of the support (60). The inner shoulder (63) is located between the head (26) and the base (21). A locking rod (27) passes through the inner shoulder (63) and the elastic unlocking system (50). For example, the elastic unlocking system (50) includes an elastic block or unlocking spring (51) having a coil (52) that is fixed to the inner shoulder (63) or fixed to the inner shoulder (63).

[0081] FIGS. 3 to 6 illustrate the operation of the first variation of the first alternative.

[0082] In the locking step of FIG. 3, the support (60) is pressed into a second position (POS2) by the control device (30). The pin (25) is partially placed within the passage (22). The elastic locking system (40) and the elastic unlocking system (50) are slightly compressed to keep the pin (25) in place, that is, to prevent the pin (25) from translationally moving relative to the support (60) due to, for example, the influence of vibration.

[0083] Referring to FIG. 4, the pilot can operate the control unit (l0) to switch to unlock mode. The support (60) is moved to a first position (POS1) away from the base (21) in the direction of the arrow (F2). The distance (DIS) between the end wall (61) and the base (21) increases. Then, the elastic locking system (40) is in a stationary state without being compressed or extended. The elastic locking system (40) probably no longer contacts the pin (25), and the elastic locking system (40) is supported by the end wall (61).

[0084] When the pivoting assembly (12) is slightly out of axial alignment, the base (21) presses the pin (25), as shown in FIG. 4. The base (21) applies a shear force to the pin (25). If there is a shear force greater than a threshold between the base (21) and the pin (25), the pin (25) does not move. Then, due to the translational movement of the support (60), the elastic unlocking system (50) is compressed. This elastic unlocking system (50) is corrected so that the pin (25) does not translate under these conditions. In fact, the elastic unlocking system (50) is corrected so that the pin (25) can be extracted from the passage (22) only when there is a shear force less than this threshold between the base (21) and the pin (25). Then, the fixing system (20) is in the innovative release preparation stage. For example, the elastic unlocking system (50) is configured to prevent unlocking when the lateral thrust (F1) is 20% greater than the thrust threshold, and allows the pivoting assembly to pivot around the pivot axis (AXP) when the pivoting assembly is not pivotably locked.

[0085] Referring to FIG. 5, as soon as the shear force between the base (21) and the pin (25) falls below a threshold value, the elastic unlocking system (50) expands. When the support (60) is not moved by the control device (30), the elastic unlocking system (50) applies force to the pin (25) to cause the pin (25) to pass through the passage (22). Then, the fixed system (20) is in the unlocking stage.

[0086] When the unlock mode is activated, depending on the relative position of the pin (25) and the base (21), the fixed system (20) can directly switch from the locking stage to the unlocking stage.

[0087] From this point, the pilot can operate the control device (30) to switch to lock mode. The support (60) moves toward the base (21) in the direction of the arrow (F3) in FIG. 6 to move to a second position (POS2). The distance (DIS) between the end wall and the base (21) is reduced.

[0088] When the pin (25) is aligned with the passage (22), the fixing system (20) can be switched to the fixed stage of FIG. 3. Otherwise, referring to FIG. 6, the pin (25) comes into contact with the base (21). Then, the elastic locking system (40) is compressed due to the translational movement of the support (60). In contrast, the elastic unlocking system (50) remains in a stationary state without being compressed or extended. The elastic unlocking system (50) probably no longer comes into contact with the pin (25), and this elastic unlocking system (50) is held by the inner shoulder (63). Then, the fixing system (20) is in a preparatory stage that allows it to automatically enter the locking stage when the pin (25) is aligned with the passage (22).

[0089] FIGS. 7 through 10 illustrate a second variation of the first alternative. Referring to FIG. 7, the support (60) is now fixed to the stand (11), for example, the stand (11).

[0090] In addition to the head (26) and locking rod (27) mentioned above, the pin (25) includes an entry rod (28) that is fixed to the head (26), i.e., connected to the head. The locking rod (27) and the entry rod (28) are located on both sides of the head (26) along the translational axis (AXT). The entry rod (28) also passes through the end wall (61) so as to extend partially outside the support (60).

[0091] Accordingly, the entry rod (28) cooperates with the control device (30) and the elastic unlocking system (50). This entry rod (28) may include an upper portion (29) that supports the tube (70). The control device (30) may include a cable (33) that passes through the wall of the tube to reach a plate (71) that is translated and guided within the tube (70). The cable (33) may be connected, for example, to the handle or output shaft (35) of an actuator (34) controlled by a human-machine interface.

[0092] The elastic unlocking system (50) may be positioned between the wall (72) and the plate (71). The elastic unlocking system (50) may include a spring or equivalent, such as an elastic block made of elastomer, for example. The stiffness of the elastic unlocking system (50) along the translational axis (AXT) may be greater than the stiffness of the elastic locking system (40) along the translational axis.

[0093] In the locking step of FIG. 7, the cable (33) is moved toward or released toward the base (21). Then, the plate (71) is positioned as close as possible to the base (21) at the locking position (POS3). The elastic locking system (40) and the elastic unlocking system (50) may be slightly compressed to hold the pin (25), that is, to prevent the pin (25) from moving excessively, for example, due to the influence of vibration.

[0094] Referring to FIG. 8, the operator can operate the control unit (30) to switch to unlock mode. The plate (71) moves upward to the unlock position (POS4). When the pivoting assembly (12) is slightly out of axial alignment, the base (21) compresses the pin (25). The base (21) applies a shear force to the pin (25). If there is a shear force greater than a threshold between the base (21) and the pin (25), the pin (25) does not move. The translational movement of the plate (71) compresses the elastic unlock system (50). Then, the locking system (20) is in the innovative unlock preparation stage.

[0095] Referring to FIG. 9, as soon as the shear force between the base (21) and the pin (25) falls below a threshold value, the elastic unlocking system (50) expands and applies force to the pin (25), causing the pin to come out of the passage (22). Then, the fixing system (20) is in the unlocking stage.

[0096] When the unlock mode is activated, depending on the relative position of the pin (25) and the base (21), the fixed system (20) can directly switch from the locking stage to the unlocking stage.

[0097] From this point, the pilot can operate the control device (30) to switch to lock mode. The plate (71) is moved toward the base (21) to the lock position (POS3).

[0098] When the pin (25) is aligned with the passage (22), the fixing system (20) can be switched to the locking phase of FIG. 7. Otherwise, referring to FIG. 10, the pin (25) comes into contact with the base (21). Then, the elastic locking system (40) is compressed due to the translational movement of the pin (25) relative to the support (60). In contrast, the elastic unlocking system (50) is in a stationary state, is not compressed or extended, and the cable (33) may be supported. Then, the fixing system (20) is in the ready phase.

[0099] FIGS. 11 through 15 illustrate a second alternative comprising a pin (25) that can rotate with respect to the base in particular. Referring to FIG. 12, the pin (25) can enter a passage (22) formed by a radial notch of the base (21).

[0100] According to FIG. 11, the pin (25) is supported by a lever (75) pivotally connected to the stand (11). Then, an elastic locking system (40) is positioned between the stand (11) and the lever (75).

[0101] Furthermore, the control device (30) includes a cable (33) connected to a panel (76) that can translate along the guide (77). An elastic unlocking system (50) is positioned between the panel (76) and a partition (78) of the guide (77) through which the cable (33) passes. The cable (33) may be connected to a handle as in the illustrated example, or connected to an actuator, for example, via one or more bell cranks.

[0102] Next, the guide (77) is fixed to the lever (75).

[0103] In the locking step of FIG. 11, the cable (33) is pulled or released by the lever (75). Then, the panel (76) is positioned as close as possible to the lever (75) at the locking position (POS5). The elastic locking system (40) and the elastic unlocking system (50) may be slightly compressed. The lever (75) pivots to position the pin (25) in the passage (22).

[0104] Referring to FIG. 13, the operator can operate the control unit (30) to switch to unlock mode. The panel (76) is moved to the unlock position (POS6). When the pivoting assembly (12) is slightly out of axial alignment, the base (21) presses the pin (25). The translational movement of the panel (76) compresses the elastic unlock system (50). Then, the locking system (20) is in the innovative unlock preparation stage.

[0105] Referring to FIG. 14, as soon as the shear force between the base (21) and the pin (25) falls below a threshold value, the elastic unlocking system (50) expands and applies force to the guide (77) pivoting the lever (75), causing the pin (25) to pass through the passage (22). Then, the fixing system (20) is in the unlocking stage.

[0106] From this point, the pilot can operate the control unit (30) to switch to lock mode. The panel (76) is controlled to move once again to the lock position (POS5). When the pin (25) is aligned with the passage (22), the locking system (20) can be switched to the locking stage of FIG. 11. Otherwise, the pin (25) comes into contact with the base (21). Then, the lever (75) compresses the elastic locking system (40). Then, the locking system (20) is in the preparation stage shown in FIG. 15.

[0107] Naturally, various modifications are possible with respect to the implementation of the present invention. Although various embodiments have been described above, it should be readily understood that it is impossible to thoroughly identify all possible embodiments. It is naturally possible to replace the described means with equivalent means without departing from the scope of the present invention and the claims. Explanation of the symbols

[0108] 1 : Rotary-wing aircraft 2 : Airframe 4: Main rotor 5: Rear rotor 6 : Landing System 7 : Landing Gear 8: Auxiliary landing gear 10: Pivot landing gear 11: Stand 12: Pivoting assembly 13: Cylinder 14: Damper 15 : Contact member 16 : Scissors 20: Fixed system 21: Base 22 : Passage 25 : Pin 26 : Head 27 : Locking Load 28 : Entry Load 30 : Control Device 31 : Handle 32 : Outer shell 33 : Cable 34 : Actuator 35: Output shaft 40: Elastic locking system 41: Locking spring 42, 52: Fixing coil 50 : Unlock system 51 : Release spring 60: Hollow support 61: End wall 62: Open end 63: Inner shoulder 70 : Tube 71 : Plate 72 : Wall 75 : Lever 76 : Panel 77 : Guide 78 : Partition 100 : Ground 150 : Wheel 270 : Vulnerable link area AXROT: Wheel axis AXP: Pivot axis AXT: Translation axis DIS: Distance POS1: Location 1 POS2: Location 2 POS3: Locked position POS4: Unlocked position

Claims

Claim 1 A landing gear (10) having a pivoting assembly (12) that supports a contact member (15) configured to contact a stand (11) and a ground (100), wherein the pivoting assembly (12) can rotate about a pivot axis (AXP) with respect to the stand (11), and the landing gear (10) has a fixed system (20) comprising a movable pin (25) and a control device (30) configured to request the application of a lock mode or an unlock mode, wherein the fixed system (20) includes a passage (22), wherein the pin (25) is outside the passage (22) during the unlock phase of the unlock mode, and wherein the pin (25) can move in the passage at an azimuth with respect to the pivot axis (AXP) during the lock phase of the lock mode, and wherein the fixed system (20) is in the lock mode, unless the pin (25) enters the passage (22), during the preparation phase of the lock mode A landing gear (10) having an elastic locking system (40) that pushes the pin (25) into the passage (22) as soon as the pin becomes aligned with the passage (22) in the fixed stage against the base (21), and the fixed system (20) includes an elastic unlocking system (50) configured to move the pin (25) out of the passage (22) when the activation of the unlocking mode is commanded by the control device (30), the passage (22) is provided to the base (21) fixed to the pivoting assembly, and the elastic unlocking system (50) is corrected so that the pin (25) can be extracted from the passage (22) only when the shear force between the base (21) and the pin (25) is less than a threshold value. Claim 2 A landing gear (10) characterized in that, in claim 1, the pin (25) can be translated along the translation axis (AXT) relative to the base (21). Claim 3 In paragraph 2, the landing gear (10) is characterized in that the fixed system (20) includes a hollow support (60) extending toward the base (21) along a translational axis (AXT) from the end wall (61) to the open end (62), the open end (62) is positioned between the end wall (61) and the base (21), the pin (25) includes a head (26) fixed to a locking rod (27), the head (26) is positioned in the hollow support (60), and the locking rod (27) exits through the open end (62) of the hollow support (60) at least during the locking stage, and the elastic locking system (40) is positioned between the end wall (61) and the head (26). Claim 4 In paragraph 3, the landing gear (10) is characterized in that the elastic locking system comprises a locking spring (41) having a coil (42) fixed to the end wall (61). Claim 5 A landing gear (10) characterized in that, in paragraph 3, the support member (60) can be translated relative to the stand (11), and the control device (30) is connected to the support member (60). Claim 6 A landing gear (10) characterized in that, in claim 5, the elastic unlocking system (50) is positioned between the head (26) and the inner shoulder (63) of the support (60), the locking rod (27) passes through the inner shoulder (63), and the inner shoulder (63) is located between the head (26) and the base (21). Claim 7 In claim 6, the landing gear (10) is characterized in that the elastic unlocking system (50) comprises an unlocking spring (51) having a coil (52) fixed to the inner shoulder (63). Claim 8 A landing gear (10) characterized in that, in paragraph 2, the support member (60) is fixed to the stand (11), and the pin (25) is fixed to the head (26) and includes an entry rod (28) passing through the end wall (61) of the support member (60). Claim 9 In claim 8, the entry rod (28) extends from the head (26) to the top (29) fixed to the hollow tube (70), the control device includes a cable (33) extending through the wall (72) of the tube (70) to a plate (71) that can be translated within the tube (70), and the elastic unlocking system (50) is positioned between the wall (72) and the plate (71), characterized in that the landing gear (10). Claim 10 A landing gear (10) characterized in that, in paragraph 2, the rigidity of the elastic unlocking system (50) along the translation axis (AXT) is greater than the rigidity of the elastic locking system (40) along the translation axis. Claim 11 A landing gear (10) characterized in that, in claim 1, the pin (25) is supported by a lever (75) pivotably connected to the stand (11), the elastic locking system (40) is positioned between the stand (11) and the lever (75), the control device (30) includes a cable (33) connected to a panel (76) that can translate within a guide (77), the guide (77) is connected to the lever (75), and the elastic unlocking system (50) is positioned between the panel (76) and a partition (78) of the guide (77) through which the cable (33) passes. Claim 12 A landing gear (10) according to claim 1, wherein the contact member (15) comprises a wheel (150) capable of rotating about a wheel axis (AXROT) with respect to the pivoting assembly (12), and wherein the wheel axis (AXROT) is different from the pivot axis (AXP). Claim 13 A rotary-wing aircraft (1) comprising at least one pivot-type landing gear (10) according to paragraph 1. Claim 14 A method for locking and unlocking a landing gear (10) having a pivoting assembly (12) that supports a contact member (15) configured to contact a stand (11) and a ground (100), wherein the pivoting assembly (12) can rotate about a pivot axis (AXP) with respect to the stand (11), and the landing gear (10) has a fixing system (20) configured to fix the pivoting assembly (12) within a predetermined position range with respect to the stand (11) during the locking phase of a locking mode and to allow unlimited pivoting of the pivoting assembly (12) with respect to the stand (11) during the unlocking phase of an unlocking mode, wherein the fixing system (20) includes a movable pin (25) and a control device (30) configured to request the application of a locking mode or an unlocking mode, and the fixing system (20) has a passage (22) provided in a base (21) fixed to the pivoting assembly The method comprises: ο activating the control device (30) to switch to a locking mode when the fixed system (20) is in an unlocking mode, and then (i) moving the pin (25) into the passage (22) when the pin (25) aligns with the passage (22); and (ii) using an elastic locking system (40) to compress the pin (25) against the base (21) when the pin (25) does not align with the passage (22), and moving the pin (25) into the passage (22) as soon as the pin (25) aligns with the passage (22).A method for locking and unlocking a landing gear (10), comprising: activating the control device (30) to switch to an unlock mode when the fixed system (20) is in a lock mode; compressing the elastic unlock system (50) when the pin (25) is in the passage (22) and in contact with the base (21); and (i) maintaining the pin (25) in the passage (22) as long as the pin (25) receives a shear force greater than a threshold value, wherein the fixed system (20) is in a release preparation stage, and (ii) as soon as the pin (25) receives a shear force less than a threshold value, expanding the elastic unlock system (50) and discharging the pin outside the passage (22) by the expansion effect of the elastic unlock system (50) to switch to an unlock stage.

Images