Patent ID: 12228197

DETAILED DESCRIPTION

The EMA of this disclosure will be described in relation to an actuator for an aircraft and, in particular, for controlling movement of a spoiler on an aircraft wing. It should be noted, however, that other applications can be envisaged for the EMA of this disclosure, that fall within the scope of the claims, and the description is by way of example only.

FIG.1shows a compact rotary EMA actuator1according to the disclosure. The EMA is mounted within an essentially cylindrical body10extending along an axis A. The EMA has an interface20to the aircraft/stationary main part of an aircraft wing (not shown). A connecting rod30extends from an external mobile crown XX. The connecting rod30has a first end31that is connected to the output of the actuator as will be described further below, to cause rotation of the connecting rod30according to the motor drive. The opposite, second end32of the rod is configured to be attached to the part or surface to be moved by the actuator e.g. the spoiler (not shown). The second end32of the connecting rod30may be provided with an eye33for attachment to a part of the movable surface. A load sensor (not shown) may be provided in or on the connecting rod30. A first portion101of the EMA is configured to house an electrical motor as described further below and an end110forms an interface for electrical connection with an electrical control unit, ECU, (not shown). The ECU can be any suitable type.

An intermediate portion102of the EMA is configured to house the gear assembly and to provide the interface between the actuator output and the connecting rod30. The other end portion103of the EMA is configured to house the actuator solenoid and the anti-extension, maintenance mode system parts described further below.

The fact that the functional components of the EMA, as described further below, can all be arranged around the axis A means that the EMA unit as a whole is relative compact and light compared to hydraulic systems or other more distributed actuators at Aircraft level

Referring now toFIG.2, the functional parts of the EMA will now be described in more detail.

The EMA includes an electrical motor200with an output shaft201that extends along the EMA axis A and which drives a rotary output300via a gear assembly400(described further below). The motor is controlled by means of a command from the ECU. The motor shaft201is supported by and extends through bearings202and terminates in a conical end portion203which forms part of a synchronizer, including a clutch and ratchet, described further below. The motor shaft201also has a decoupling portion204which is a break in the shaft that is bridged by an end section41of a maintenance mode lever40(described further below). In normal operation, the motor shaft between the motor and the conical end portion203is effectively a complete shaft as the break is bridged by the end section of the maintenance mode lever40. The gear assembly400is configured with a gear ratio to cause the rotary output300to rotate at speed which is a predefined fraction of the rotational speed of the motor shaft201. The rotary output300is arranged to be connected to the connecting rod30to move the surface/part according to the command. This is the normal, active mode of operation.

An output position sensor (OPS)500may also be provided to provide an indication of the rod position to the ECU.

The EMA also includes components necessary to operate the EMA in the anti-extension mode and the maintenance and to provide the droop function. These modes and functions, and the component parts, will be described further below.

Briefly, however, a clutch600and ratchet wheel700mechanism, together with a solenoid800cooperate in the anti-extension mode. A maintenance mode lever40and cam arrangement50cooperate in the maintenance mode, and the clutch600and the cam arrangement50cooperate for the droop function.

The gear system400includes a first gear stage401mounted around the motor shaft201. Rotation of the motor shaft rotates the first gear stage. A second gear stage402is mounted around the first gear stage and is in toothed or meshing engagement therewith such that rotation of the first gear stage causes rotation of the second gear stage but at a lower rotational speed according to the gear ratio. The second gear stage402is engaged with the rotary output300to cause corresponding rotation thereof which, in turn, causes rotation of the connecting rod30. The gear system therefore has compound gear kinematics.

FIG.3shows the configuration of the EMA when operating in the active mode.

In this mode, the solenoid,800is energised (power is provided) and so the synchronizer900components are held out of engagement with the conical end203of the motor shaft201. In more detail, when the solenoid is in this energised state, the solenoid head801engages behind the clutch600of the synchronizer900pulling the clutch away from the conical end203and compressing clutch spring601. The motor shaft, therefore, rotates freely on rotation of the motor, causing rotation of the gear assembly400and, thus, the rotary output300.

The EMA of the disclosure is further designed to operate in an anti-extension mode, shown inFIG.4) to prevent the actuator extending in the positive direction from the zero or neutral position in the event of power failure. The features ofFIG.4that are the same as inFIG.3will not be described again here. As mentioned above, for safety and efficiency reasons, if power fails, the actuator should be configured to return e.g. the spoiler to its neutral or flat position and should prevent inadvertent or uncommanded lifting of the spoiler to the extended position due to e.g. aerodynamic forces. The power failure results in the SOV800being de-energised and so the head801no longer acts against the force of the spring601and the spring601relaxes to its extended state. This moves the clutch and the synchronizer900to the left in the drawings (arrow X). The synchronizer900is formed with a receptacle901having a shape that matches the shape of the conical end203of the motor shaft201such that movement of the synchronizer to the left (in the drawings) due to relaxation of the spring601causes the receptacle to engage with the conical end203of the motor shaft. When the two conical parts are engaged, rotation of the motor shaft201is transmitted through the engaged conical end and receptacle causing the synchronizer900to rotate. The other end of the synchronizer902forms a ratchet that engages with a pawl950that ensures that the ratchet can only rotate in one direction of rotation. Thus, in this mode, the motor shaft can rotate, and drive the output, in a first direction of rotation under drive of the motor200, but is prevented from rotation in the opposite direction of rotation by the ratchet. The ratchet is configured such that the prohibited direction of rotation corresponds to the actuator extension direction, and so in this mode, extension is prevented.

The above, with reference toFIG.4, describes the anti-extension function for positive strokes. As mentioned above, though, actuator systems have recently been developed that enable the actuator to operate with a negative stroke i.e. to actively retract further from the zero or neutral position. This so-called droop function allows, for example, an actuator controlled spoiler to move down relative to a wing body to follow downward movement of a wing flap. Under normal active operation, the spoiler is also able to return from the droop position by an extension operation of the EMA—i.e. a positive stroke.

A problem arises though if the EMA Is operating in the anti-extension mode where it is prevented from moving in the extension direction when power is lost. As can be seen in relation toFIG.4, described above, if the solenoid is deactivated, the EMA moving the spoiler is prevented from operating in the extension direction. If, for example, the spoiler is in the droop zone to follow movement of a wing flap, and then power is lost, the wing flap will want to return to its neutral, non-extended position, but the spoiler, resting on the wing flap and so exerting a force on the flap against its movement to the neutral position, will prevent the flap from returning to neutral and the spoiler is not able to extend (i.e. move away from the flap) because of the anti-extension operation of the EMA.

The arrangement of the present disclosure provides a solution to this problem by use of a cam feature described further below with reference toFIGS.5and7.

FIG.5shows the operation of the EMA when the system is in anti-extension mode—i.e. power has failed and so the SOV is not energised, the spring601is expanded and the clutch ratchet and pawl mechanism is engaged to prevent rotation in the extension direction. The EMA is, however, provided with a cam feature50which, as described further below, is provided with a cam profile that is designed to allow the EMA to operate in the extension direction even when the SOV is de-energised when the rotational position of the output300indicates that the EMA is in negative stroke—i.e. in a droop state, whereby the cam profile rotates with the rotary output300.

The cam feature50is shown in detail inFIG.7. The cam feature50is an annular structure mounted about the EMA axis A and a ratchet wheel connected to the synchronizer900, and comprises an outer cam profile61that is connected to and rotates with the connecting rod30or with the EMA output300. The outer cam profile61is not circular but, rather, has a smaller diameter region defining a droop zone and a larger diameter region defining a positive stroke zone. The cam system further includes a pawl63that is pivotal about a pivot point64and has a ratchet engaging end66. A contact structure65is provided at the other end of the pawl63, at or near the pivot point64. The cam system further includes the ratchet wheel67of the synchronizer radially inwards of the outer cam profile.

The contact structure65comprises a piston51and a spring52which force the pawl to tilt into engagement with the ratchet wheel.

As the connecting rod30(or output300) rotates, it causes a corresponding rotation of the outer cam profile61. So long as the output300corresponds to a neutral position or positive stroke (i.e. in a non-droop zone), the larger diameter part of the cam profile passes the back of the pawl63. The pawl at that moment is engaged, due to the force of the spring52and the piston51, into the ratchet wheel. The pawl is positioned and located such that during time of rotation while the larger diameter part of the cam profile is passing the pawl, the cam profile rides across the contact structure65of the pawl and so the ratchet engaging end66of the pawl pivots radially inwards about the pivot point bringing the ratchet engaging end into engagement with the teeth68of the ratchet wheel67. When the output30corresponds to the droop state, however, the smaller diameter part of the cam profile passes the pawl63causing the cam to press on the back of the pawl, compressing the spring52and thus causing the pawl to lift and avoid ratchet engagement with the teeth of the ratchet wheel. Thus, the motor shaft201is disconnected from the synchronizer900even though the SOV is de-energized, when in droop state and the output is free to turn in the direction allowing extension of the spoiler.

Therefore, due to the operation of the cam system, the anti-extension features are either engaged (which in the non-droop or positive stroke state) or disengaged, when in droop, based on the rotational position of the output/connecting rod.

In the droop zone, the pawl is lifted up so that the ratchet wheel can rotate in both directions.

Operation of the EMA in maintenance mode will be described with reference toFIG.6. In maintenance mode, the motor should be disengaged so that it does not drive the output30and the system ratchets should be disengaged to enable maintenance personal to manually turn the output without any resistance. By disengaging the motor, there is no risk of the output moving while being held by a maintenance worker even if the motor is accidentally activated. The EMA is set to maintenance mode by moving the end41of the motor maintenance lever40out of engagement with the motor shaft across the decoupling portion204using a tool such as a screw driver. In one example, the end41of the lever40is secured in place by means of a pivotal bracket that is, in normal operation, locked in a first, securing position, by a locking pin. The locking pin has a slotted end engaged to receive a screw driver or similar tool to rotate the pin. The circumference of the pin body is formed with one or more discrete flat portions, and other rounded portions which are, in normal operation, in engagement with the bracket. If the pin is rotated so that a flat portion is aligned with the bracket, the bracket is released and pivots out of the secured position thus releasing the end41of the lever from bridging the decoupling portion of the motor shaft and this disengaging the motor from the rest of the EMA.

The EMA of this disclosure is therefore a compact cylindrical housed unit containing functional components to operate the EMA in the various modes as well as to house the motor and solenoid of the SOV. Furthermore, the EMA is configured to allow extension when the EMA is in droop state even if power has failed.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, element components, and/or groups thereof.

While the present disclosure has been described with reference to an example embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present disclosure without departing from the essential scope thereof. Therefore, it is intended that the present disclosure not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this present disclosure, but that the present disclosure will include all embodiments falling within the scope of the claims.