FR3115266A1 - PROPULSION ASSEMBLY FOR AN AIRCRAFT EQUIPPED WITH A DEVICE FOR LOCKING THE PROPELLER IN ROTATION - Google Patents

Abstract

The invention relates to a propulsion assembly (22) with a propeller for an aircraft (20) comprising a nacelle (24), a propeller (26), and a device (34) for blocking the rotation of the propeller (26) comprising a locking arm (46) which is pivotally mounted between a locking position in which it cooperates with at least one notch (42) of the other locking element (36) to block the rotation of the propeller (26) and a release position in which the arm (46) is moved away from said other locking element (36); characterized in that the locking arm (46) is elastically returned to its release position, while it is urged towards its locking position by means of an actuator (58). Figure for abstract: Figure 3

Description

PROPULSION ASSEMBLY FOR AN AIRCRAFT EQUIPPED WITH A DEVICE FOR LOCKING THE PROPELLER IN ROTATION

Technical field of the invention

The invention relates to a propeller propulsion assembly for an aircraft comprising a nacelle, a propeller mounted for rotation about an axis of rotation in the nacelle, and a device for locking the rotation of the propeller in at least one angular position indexed with respect to the nacelle, the blocking device comprising:

- At least a first stationary locking element which is mounted fixed relative to the nacelle;

- At least one second rotary locking element solidly with the propeller;

- one of the two locking elements comprising a locking arm which is pivotally mounted between a locking position in which it cooperates with at least one notch of the other locking element to block the rotation of the propeller and a position release in which the arm is moved away from said other locking element.

Technical background

Such propeller propulsion assemblies are for example used in aircraft with vertical take-off and landing, also called "VTOL", an acronym for "Vertical Take Off and Landing". In this context, it is possible to equip the aircraft with several propeller propulsion assemblies so as to distribute the thrust foci and seek the best propulsive yields on the aircraft.

These propeller propulsion units can be disabled depending on the flight configuration of the aircraft. When propeller propulsion assemblies are deactivated, their propeller is liable to harm the aerodynamic performance of the aircraft, for example by creating a drag force, or else by creating local disturbances in the air flows.

This is particularly the case of the propeller propulsion assemblies used for the lift of the aircraft. These propeller propulsion units are indeed used only for landing, take-off or hovering. When the aircraft is moving horizontally in a cruising phase, it is preferable to block the rotation of the propellers in an indexed angular position in which their drag is minimal. For propellers having two blades, the drag is minimized when the blades are arranged parallel to the horizontal displacement of the aircraft.

To solve this problem, propulsion assemblies have already been proposed equipped with devices for locking the propellers in their indexed position in which the impact of the blades of the propeller on the aerodynamic performance of the aircraft is minimized.

However, in current propulsion systems, the propellers are blocked by means of their electric propulsion motor.

However, such a solution requires electricity consumption throughout the duration of the locking of the propeller in its indexed angular position.

Furthermore, such an electric motor does not make it possible to obtain a sufficiently precise angular positioning to guarantee that the propeller is properly locked in the angular position providing the best aerodynamic advantages.

The invention proposes a propeller propulsion assembly for an aircraft comprising a nacelle, a propeller mounted for rotation around an axis of rotation in the nacelle, and a device for locking the rotation of the propeller in at least one angular position. indexed with respect to the nacelle, the blocking device comprising:

- At least a first stationary locking element which is mounted fixed relative to the nacelle;

- At least one second rotary locking element solidly with the propeller;

- one of the two locking elements comprising a locking arm which is pivotally mounted between a locking position in which it cooperates with at least one notch of the other locking element to block the rotation of the propeller and a position release in which the arm is moved away from said other locking element;

characterized in that the locking arm is elastically returned to its release position, while it is urged towards its locking position by means of an actuator.

According to another characteristic of the propulsion assembly produced according to the teachings of the invention, the locking device comprises an elastic return member to allow its elastic return to its release position.

According to another characteristic of the propulsion assembly produced according to the teachings of the invention, the actuator acts on the locking arm via an elastic energy storage member which urges the locking arm towards its locked position when the actuator is activated.

According to another characteristic of the propulsion assembly produced according to the teachings of the invention, the elastic energy storage member is a helical spring, a first end of which is connected to the locking arm, while a second end is connected to a movable actuating element of the actuator.

According to another characteristic of the propulsion assembly produced according to the teachings of the invention, the actuator is a rotary actuator, such as an electric motor, which comprises a movable actuation element formed by a rotary shaft.

According to another characteristic of the propulsion assembly produced according to the teachings of the invention, the actuator is a linear actuator, such as a linear motor or a jack, which comprises a movable actuation element formed by a sliding rod.

According to another characteristic of the propulsion assembly produced according to the teachings of the invention, the locking element which comprises the notch has a locking plate coaxial with the axis of rotation comprising a circular peripheral edge in which the notch is made. , the locking arm comprising a lug intended to be received in the notch when it occupies its locking position and the propeller occupies its indexed angular position.

According to another characteristic of the propulsion assembly produced according to the teachings of the invention, the lug is provided with a roller which is intended to roll on the circular peripheral edge of the plate when the locking arm is urged towards its position of locking and that the propeller does not occupy its indexed angular position.

According to another characteristic of the propulsion assembly produced according to the teachings of the invention, the notch belongs to the rotary locking element, the locking arm belonging to the stationary locking element.

According to another characteristic of the propulsion assembly produced according to the teachings of the invention, the locking arm is pivotally mounted around a pivot axis orthogonal to the axis of rotation.

According to another characteristic of the propulsion assembly produced according to the teachings of the invention, the locking arm is pivotally mounted around a pivot axis which extends tangentially with respect to the direction of rotation of the propeller.

According to another characteristic of the propulsion assembly produced according to the teachings of the invention, the notch has two slopes which allow the extraction of the lug from the notch when a torque greater than a predetermined threshold value is applied to the helix.

Brief description of figures

Other characteristics and advantages of the invention will appear during the reading of the detailed description which will follow for the understanding of which reference will be made to the appended drawings in which:

There is a perspective view which schematically represents an aircraft equipped with propellant lift assemblies produced according to the teachings of the invention.

There is a perspective view on a larger scale which represents the hub of a propeller of a propulsion assembly comprising a locking device produced according to the teachings of the invention.

There is a perspective view which shows only the blocking device which is intended to equip the propulsion unit of the .

There is a side view showing the locking device of the in a release position.

There is a view similar to that of the which represents the blocking device in a locking position.

There is a top view which partially shows a plate of the locking device which is equipped with a locking notch.

Detailed description of the invention

In the rest of the description, elements having an identical structure or analogous functions will be designated by the same reference.

In the remainder of the description, a longitudinal orientation indicated by the arrow "L" in the figures, which is directed from front to rear in the direction of movement of the aircraft, will be adopted without limitation. We will also use a vertical orientation indicated by the arrow "V" which is directed from bottom to top perpendicular to the longitudinal direction.

Radial orientations will be used which are directed orthogonally to the vertical direction and which are directed from the inside close to the axis "Z" of rotation of the helix 26 towards the outside. A tangential direction will also be used which is directed orthogonally to a radial direction and to the vertical direction.

We represented at the an aircraft 20 which comprises several propeller propulsion assemblies made according to the teachings of the invention. This is a vertical take-off and landing aircraft, also called by its English acronym "VTOL" for "Vertical Take Off and Landing". In this respect, the aircraft 20 comprises propeller propulsion assemblies 22, referred to as "lift" assemblies, which are intended to cause a vertical lift thrust of the aircraft 20. These propulsion propulsion assemblies 22 are here arranged on a tailplane of the aircraft 20 as well as on a fuselage of the aircraft 20.

The aircraft 20 also comprises propulsion assemblies 24, called traction assemblies, which are intended to cause a longitudinal thrust to allow the movement of the aircraft 20 forwards. The traction propulsion units 24 are here arranged on a wing of the aircraft 20.

The invention is advantageously, but not exclusively, applied to propulsion assemblies 22 for lift.

The lift propulsion assemblies 22 have a similar design. Thus, a single propulsion assembly 22 for lifting will be described below, the description being applicable to the other propulsion assemblies 22 for lifting.

As shown in the , the propulsion assembly 22 of lift comprises a nacelle 24 which is intended to be mounted on a structural element of the aircraft 20, for example the fuselage or the empennage. For example the nacelle 24 is mounted fixed on the structural element.

The propulsion unit 22 also comprises a propeller 26 which is mounted for rotation in the nacelle 24 around a rotation axis "Z". The propeller 26 is here attached to the upper end of a propeller shaft 28 via a hub 30. Blades 32 extend radially from the hub 30. They extend above the nacelle 24. The blades 32 are evenly distributed around the hub 30. The propeller 26 here comprises two opposing blades 32.

The propeller 26 is intended to be driven in rotation by means of a propulsion motor (not shown), for example an electric motor. The propulsion motor thus provides motor torque to the propeller 26 via the propeller shaft 28 to cause it to rotate so that the propeller can provide the lift thrust necessary for the operation of the aircraft 20. When no torque motor is supplied to the propeller 26, the latter is free to rotate under the effect of its inertia and/or the aerodynamic disturbances created by the movement of the aircraft and by the wind.

The propulsion assembly 22 of lift is equipped with a device 34 for locking the rotation of the propeller 26 in at least one indexed angular position with respect to the nacelle 24. The indexed angular position corresponds to an angular position in which the drag of the propeller 26 is minimized in the direction of longitudinal movement of the aircraft 20. In the case of a propeller 26 with two blades 32, such as that shown in the figures, the propeller 26 can be stopped in two positions indexed in which the blades 32 extend longitudinally parallel to the direction of movement of the aircraft 20.

The locking device 34 comprises at least one rotary locking element 36 which is mounted integral in rotation with the propeller 26. As shown in more detail in Figures 3 to 5, the rotary locking element 36 comprises a locking plate 38 coaxial with the "Z" axis of rotation which is attached to the propeller shaft 28. The locking plate 38 has a circular peripheral edge 40 . At least one notch 42 is formed in the circular peripheral edge 40 . The locking plate 38 here comprises two opposite notches 42 to enable the propeller 26 to be stopped in one or the other of its two indexed angular positions.

The locking device 34 also comprises at least one stationary locking element 44 which is mounted on a support fixed relative to the nacelle 24. The stationary locking element 44 here comprises a locking arm 46 which is pivotally mounted between a position lock, shown in , in which the arm 46 cooperates with at least one of the notches 38 of the locking plate 38 to block the rotation of the propeller 26 and a release position, illustrated in FIGS. 3 and 4, in which the locking arm 46 is moved away from the locking plate 38.

More particularly, a first free end of the locking arm 46 comprising a lug 48 which is intended to be housed in the notch 42 when the locking arm 46 occupies its locking position and the propeller 26 occupies one of its positions. indexed angular.

An opposite end of the locking arm 46 is pivotally mounted in a yoke 50 which is here fixed mounted on the nacelle 24. The locking arm 46 is more particularly pivotally mounted about a pivot axis "X" orthogonal to the axis "Z" of rotation. More particularly, the locking arm 46 is mounted to pivot about a pivot axis "X" which extends tangentially with respect to the direction of rotation of the propeller 26. The locking arm 46 here extends generally vertically from its axis "X" of pivoting in the direction of the locking plate 38. More particularly, the locking arm 46 is slightly inclined radially outwards in its release position, so as to move the lug 48 away from the peripheral edge 40 of the locking plate 38, while it is slightly inclined radially towards the axis "Z" of rotation in the locked position so as to be housed in one of the notches 42.

The lug 48 of the locking arm 46 is provided with means of contact without friction against the peripheral edge 40 of the plate 38 when the locking arm 46 is urged towards its locking position and the propeller shaft 28 does not occupy not its indexed angular position. The frictionless contact means are here formed by a roller 52 which is intended to roll on the circular peripheral edge 40 of the plate 38 for locking. The roller 52 is rotatably mounted on the lug 48 about a bearing axis "Y" which extends substantially in the axis of the locking arm 46. The roller 52 is inserted into the notch 42 in the locking position.

As a variant, the frictionless contact means are formed by an antifriction coating which surrounds the lug.

The locking arm 46 is elastically returned to its release position. To this end, the locking device 34 comprises an elastic return member 54 to allow the elastic return of the locking arm 46 towards its release position. The elastic return member 54 is here formed by a torsion spring. Such an elastic return member 54 comprises, for example, a metal wire wound in turns forming a central coil. Two free end sections of the wire forming support tabs 56 extend radially from the central coil. One of the lugs 56 bears against a bearing face fixed with respect to the yoke 50, while the other of the lugs 56 bears against a face of the arm 46 for locking. The elastic return member 54 thus permanently urges the locking arm 46 towards its release position with a determined elastic return force.

In addition, the locking arm 46 is capable of being controlled towards its locking position by means of an actuator 58. The actuator 58 is of course separate from the propulsion motor.

The actuator 58 is here a rotary actuator which comprises a movable actuation element 60 formed by a shaft rotatably mounted in a fixed casing. This is an electric motor. The rotary shaft, forming the movable actuating element 60, extends parallel to the pivot axis "X" of the locking arm 46. The transmission of the rotational movement of the movable actuating element 60 to the arm 46 is produced by means of a crank 62 which is fixed to the movable actuating element 60. The crank is equipped with an eccentric crankpin 64 which is connected to the locking arm 46 by means of a connecting rod. traction.

In a variant of the invention, not shown, the actuator is a linear actuator, such as a linear motor or a jack, which comprises a movable actuation element formed by a sliding rod.

The actuator 58 here acts on the arm via an elastic energy storage member 66 which urges the arm towards its locking position when the actuator 58 is activated. Such an elastic accumulation member 66 allows the movable element of the actuator to directly occupy an active locking position even when the lug 48 is not in coincidence with a notch 42. In addition, this member 66 energy storage elastic also makes it possible to release the lug 48 from its notch 42 in the event of a malfunction of the actuator under the effect of a motor torque applied to the propeller 26 as will be explained later.

In the embodiment shown in the figures, the pull rod is here formed directly by the elastic accumulation member 66. The elastic accumulation member 66 is thus formed by a helical spring which acts in traction and of which a first end is connected to the locking arm 46, here close to the lug 48, while a second end is connected to the crank pin 64.

Furthermore, a degraded mode of operation is provided in the event of a malfunction of the actuator 58 in order to be able to extract the lug 48 from the notch 42 by applying sufficient engine torque to the shaft 28 of the propeller. To this end, the notch 42 has, in top view as illustrated in , a bowl shape comprising a bottom 68 towards which two slopes 70 converge from the peripheral edge 40 of the plate 42. The slopes 70 have an inclination which allows the extraction of the lug 48 from the notch 42 by rolling the roller 52 when a torque greater than a predetermined threshold value applied to the propeller shaft 28. This threshold value is chosen so that a torque produced solely by aerodynamic disturbances due to the movement of the aircraft 20 is insufficient to reach it. Advantageously, only the propulsion engine of the aircraft 20 is powerful enough to cause the unlocking of the propeller 26. In this case, the locking arm 46 is pivoted towards its release position against a force applied by the elastic member 66 of energy accumulation.

In normal operation, when the propulsion assembly 22 is in service, the actuator 58 is inactive and the elastic return member 54 maintains the locking arm 46 in its release position.

When the propulsion assembly 22 is no longer necessary for the operation of the aircraft 20, the propulsion engine no longer provides any engine torque. The actuator 58 is then activated so as to urge the locking arm 46 towards its locking position against the force exerted by the member 54 for elastic return. The roller 52 then comes into contact with the peripheral edge 40 of the plate 38 for locking. The elastic accumulation member 66 is stretched elastically so as to press the roller 52 against the peripheral edge 40 . The roller 52 thus rolls on the peripheral edge 40 until it reaches one of the notches 42 into which it enters under the effect of the force exerted by the energy storage member 66 . The propeller 26 is then locked in rotation in its indexed angular position.

When the propulsion unit 22 restarts, the actuator 58 is deactivated. The locking arm 46 is then elastically returned to its release position by the elastic return member 54 and the propeller 26 is free to rotate.

In the examples shown in the figures, the locking arm 46 is carried by the stationary locking element 44, while the locking plate 38 is carried by the rotating locking element 36.

In a variant of the invention, not shown, and by mechanical inversion, the locking plate belongs to the stationary locking element while the locking arm belongs to the rotating locking element.

Claims (12)

Propeller propulsion assembly (22) for an aircraft (20) comprising a nacelle (24), a propeller (26) mounted for rotation around an axis (Z) of rotation in the nacelle (24), and a device (34 ) for blocking the rotation of the propeller (26) in at least one angular position indexed with respect to the nacelle (24), the blocking device (34) comprising:
- at least a first stationary locking element (44) which is fixedly mounted relative to the nacelle (24);
- at least one second rotary locking element (36) solidly with the propeller (26);
- one of the two locking elements (36, 44) comprising a locking arm (46) which is pivotally mounted between a locking position in which it cooperates with at least one notch (42) of the other element (36 ) locking to block the rotation of the propeller (26) and a release position in which the arm (46) is moved away from said other locking element (36);
characterized in that the locking arm (46) is elastically returned to its release position, while it is urged towards its locking position by means of an actuator (58). Propulsion assembly (22) according to the preceding claim, characterized in that the blocking device (34) comprises an elastic return member (54) to enable its elastic return to its release position. Propulsion unit (22) according to any one of the preceding claims, characterized in that the actuator (58) acts on the locking arm (46) by means of an elastic element (66) for accumulating energy which urges the locking arm (46) to its locking position when the actuator (58) is activated. Propulsion assembly (22) according to the preceding claim, characterized in that the elastic energy accumulation member (66) is a helical spring, a first end of which is connected to the locking arm (46), while a second end is connected to a movable element (64) for actuating the actuator. Propulsion unit (22) according to any one of the preceding claims, characterized in that the actuator (58) is a rotary actuator, such as an electric motor, which comprises a movable actuation element (60) formed by a rotating shaft. Propulsion assembly (22) according to any one of Claims 1 to 4, characterized in that the actuator (58) is a linear actuator, such as a linear motor or a jack, which comprises a movable element (60) actuation formed by a sliding rod. Propulsion unit (22) according to any one of the preceding claims, characterized in that the locking element (36) which comprises the notch (42) has a locking plate (38) coaxial with the axis (Z) of rotation comprising a circular peripheral edge (40) in which the notch (42) is formed, the locking arm (46) comprising a lug (48) intended to be received in the notch (42) when it occupies its locking position and that the helix (26) occupies its indexed angular position. Propulsion assembly (22) according to the preceding claim, characterized in that the lug (48) is provided with a roller (52) which is intended to roll on the circular peripheral edge (40) of the plate (38) when the arm (46) locking is biased towards its locking position and that the propeller (26) does not occupy its indexed angular position. Propulsion unit (22) according to any one of the preceding claims, characterized in that the notch (42) belongs to the rotary locking element (36), the locking arm (46) belonging to the element (44) stationary lock. Propulsion unit (22) according to any one of the preceding claims, characterized in that the locking arm (46) is pivotally mounted around a pivot axis (X) orthogonal to the rotation axis (Z). Propulsion unit (22) according to any one of the preceding claims, characterized in that the locking arm (46) is pivotally mounted about a pivot axis (X) which extends tangentially with respect to the direction of rotation l propeller (26). Propulsion assembly (22) according to any one of Claims 10 to 11 taken in combination with Claim 7, characterized in that the notch (42) has two slopes (70) which allow the extraction of the lug (48) of the notch (42) when a torque greater than a predetermined threshold value is applied to the propeller (26).