Cross-Reference to Related Applications

This patent application is related to Italian Patent Application No . 102021000027833 filed on October 29 , 2021 , the entire disclosure of which is incorporated herein by reference .

Technical Field

The present invention relates to an electromechanical drive system, for applications to fixed or rotary wing aircraft .

The present invention is preferably, although not exclusively, applied to the sector of aircrafts , to which such application will refer in the following by way of example .

State Of The Prior Art

Manual mode control and autopilot mode control systems are known which are used in the electromechanical actuation of aircraft parts .

In particular, currently there are active or passive control systems diversi fied by the function that they perform, the so-called trim actuators for the autopilot mode control function and fixed rigidity spring commands for the manual mode control . This diversi fication entails flight command assemblies which are particularly bulky, heavy and comprise numerous units .

In particular, it is also known to configure such systems so that , during the manual control , a resistance to the action of the driver is imparted so as to prevent possible mal functions which would lead to disastrous accidents of the aircraft . Likewise , there are integrated control systems for performing the manual and autopilot control of the aeroplane , which comprise therein additional active systems such as actuators , solenoids or other electromechanical machines which allow passing from one mode to the other based on an external signal and controlled through additional integrated electronics .

Therefore , the need is felt for reducing the components of such control systems so as to reduce weight , bulks and production, maintenance and management costs making the entire control system of the aircraft ef ficient , nevertheless preventing active additional elements , and thus electrical consumption and heat dissipation linked to the latter, as well as the increase in weight and cost .

The obj ect of the present invention is to meet the abovedescribed requirements in an optimised and cost-ef fective manner .

Summary of the Invention

The aforementioned obj ect is achieved by an electromechanical drive system for aircraft as claimed in the appended claims .

Brief Description of the Drawings

In order to better understand the present invention, a preferred embodiment is described in the following, by way of non-limiting example and with reference to the accompanying drawings , wherein :

• Figure 1 is a schematic block diagram illustrating a drive system of an aircraft comprising a control system according to the invention;

• Figure 2 illustrates the diagram o f Figure 1 in a f irst operating condition;

• Figure 3 illustrates the diagram o f Figure 1 in a second operating condition;

• Figure 4 is a sectional perspective view illustrating a device of the control system according to the invention;

• Figure 5 is an exploded perspective view illustrating the device of Figure 4 ; and

• Figure 6 is an axial sectional view of the device of Figure 4 .

Detailed Description of the Invention

Figures 1 to 3 schematically illustrate an electromechanical drive system 1 for an aircraft , not illustrated in its wholeness for clarity .

In particular, the electromechanical drive system 1 comprises a transmission shaft 2 operatively connected to an electric machine 3 , such as an electric motor, configured to at least operate in an operating state in which it trans forms electric energy in order to drag in rotation the transmission shaft 2 .

The electromechanical drive system 1 comprises an electronic unit 4 configured to control the operation of the electric machine 3 based on data coming from a plurality of sensor means 5 and of other operating systems 6 of the aircraft communicating with the electromechanical drive system 1 .

In particular, the transmission shaft 2 is dedicated to controlling other mechanical operating systems (not illustrated of the aircraft ) . Non-limiting and non- exhaustive examples of such operating systems 6 are the onboard computer ( also called Flight Control Computer, FCC ) or the external avionics ( air data sensors , inertial navigation system) , which send to the electromechanical drive system 1 useful data for configuring the control ( trims , flight speed, envelope ) and receive information from the electromechanical drive system 1 concerning the operation thereof . A nonlimiting and non-exhaustive example of the aforementioned mechanical operating systems is the flight command assembly of the aircraft , which by means of rods , quadrants and intermediate controls connects the command of the pilot in the cockpit to the primary flight actuators .

Consequently, the electronic unit 4 comprises processing means configured to be electrically connected to the electric machine 3 , to the sensor means 5 and to the other operating systems 6 of the aircraft in order to acquire data from the latter and consequently control the electric machine 3 .

The sensor means 5 are configured to detect a physical quantity relating to an operating condition of the transmission shaft 2 . In particular, the sensor means 5 can comprise torque sensors 5 ' or position sensors 5 ' ’ installed on the rotating shaft 2 .

The electric machine 3 is advantageously connected to the transmission shaft 2 by means of a transmission assembly 7 , advantageously a reduction assembly configured to vary a torque/ speed between transmission shaft 2 and electric machine 3 . In particular, the transmission assembly 7 comprises a plurality of gears , not further described in the following .

According to the invention, the electromechanical drive system 1 compri ses a two-way transmission rotation 8 operatively placed downstream of the transmission assembly 7 and operatively connected to a clutch assembly 9 .

Speci fically, the two-way transmission rotation 8 is configured to al low the transmis sion of the torque coming from the electric machine 3 by means of the transmission assembly 7 towards the transmission shaft 2 without torque dissipation by means of the clutch assembly 9 during a first operation mode ( Figure 2 ) and to allow the transmission of the torque coming from the transmi ssion shaft 2 towards the electric machine 3 by means of the transmission assembly 7 with torque dissipation by means of the clutch assembly 9 ( Figure 3 ) with the aim to adj ust the reversibility load of the actuation system, i . e . of the torque perceived by the pilot .

In particular, according to what described above , it is evident that the transmission shaft 2 comprises a first portion 2 ' between the electric machine 3 and the transmission assembly 7 , a second portion 2 ' ' between the latter and the two-way transmission rotation 8 and a third portion between the latter towards the mechanical operating systems of the aircraft .

Advantageously, the above-described sensor means 5 are placed on the opposite side of the electric machine 3 with respect to the two-way transmission 8 ( i . e . on the transmission shaft 2 ) , whereas the transmission assembly 7 is placed on the same side of the electric machine 3 , axially between the latter and the two-way transmission 8 .

Preferably, the electromechanical drive system 1 also comprises safety devices 11 configured to interrupt the transmission of torque on the shaft on which they are placed when a predefined designed torque is reached .

Such safety devices 11 can comprise mechanical fuses , integral with two portions of the shaft to which they are provided and configured to break, thus preventing the transmission of the torque between the two portions of such shaft .

In particular, in the system according to the present invention, safety devices 11 are provided on the third portion 2 ' ' ' of the transmission shaft 2 , i . e . between the two-way transmission 8 and the sensor means 5 and on the second portion 2 ’ ’ of the transmission shaft 2 , i . e . between the transmission assembly 7 and the two-way transmission 8 .

Preferably, the clutch assembly 9 comprises adj usting means 12 configured to adj ust the braking torque imparted by the clutch assembly . Advantageously, such adj usting means 12 are mechanical adj usting means adapted to vary an axial preload of the clutch assembly 9 which increases or decreases the friction between the sliding elements relating to the same .

Advantageously, the two-way transmission 8 and the clutch assembly 9 are made as a single assembled component .

Referring to Figures 4 to 6 , an advantageous embodiment of the two-way transmission 8 is illustrated .

The two-way transmission 8 comprises a housing 101 configured to be supported rotationally free on a rotating shaft 102 which i s rigidly connected to two portions of the transmission shaft 2 , speci fically between the third and the second portions 2 ’ ’ , 2 ’ ’ ’ of the same .

The housing 101 is advantageously concentric and axially symmetrical with respect to an axi s A of the rotating shaft 102 and comprises a cylindrical portion 101a and a tubular portion 101b extending cantilevered from the outer perimeter of the cylindrical portion 101a .

The cylindrical portion 101a comprises a portion 101c configured to be integrally connected to the clutch assembly 9 . In particular, the portion 101c is configured as a toothing adapted to engage a respective toothing made in a movable portion 9 ' of the clutch assembly 9 . Such movable portion 9 ' can comprise one or more clutch plates between two fixed portions 9 ' ’ of the clutch assembly 9 . The above-mentioned adj usting means 12 advantageously comprise elastic means 104 configured to impart an axial preload between the fixed portions 9 ' ’ and the movable portions 9 ' and compression means 105 configured to vary the preload of the elastic means 104 supplied to the aforementioned portions 9 ' , 9 ' ’ .

In particular, as is illustrated, the elastic means 104 comprise a helical spring configured to be compressed by the compression means 105 which compri se a screw fixed by means of thread on a support on which the helical spring is inserted in an axially symmetrical manner with respect to the screw .

The tubular portion 101b defines a space 106 radially delimited by the tubular portion 101b and axially delimited by the cylindrical portion 101a on one side and open on the opposite side .

On such side , the two-way transmission 8 compri ses a plate 107 configured to be operatively connected to the transmission assembly 7 of the electromechanical drive system 1 .

The plate 107 de fines a central opening 108 configured to house a portion of the rotating shaft 102 in a rotationally free manner .

Advantageously, the housing 101 is supported on the shaft 102 by means of support means such as a bushing 108 and houses , in the space 106 defined between the tubular portion 101b and the plate 107 , a decoupling mechanism 110 .

The decoupling mechanism 110 is configured to allow the transmission of torque in both directions of rotation of the rotating shaft 102 in two di f ferent conditions : in a first condition, wherein the torque comes from the transmission assembly 7 towards the rotating shaft 102 , the decoupl ing mechanism 110 rotates within the space 106 integral with the plate 107 and the rotating shaft 102 without the clutch assembly 9 interfering with the transmission of torque ;

• in a second condition, wherein the torque comes from the rotating shaft 102 towards the transmission assembly 7 , the decoupling mechanism 110 drags the housing 101 which thus drives in rotation the movable portion 9 ' of the clutch assembly 9 generating a torque resistant to the motion of the rotating shaft 102 .

More speci fical ly, the decoupling mechanism 110 comprises a rotating body 111 , better visible in Figure 5 , defining an opening 112 configured to house through it the rotating shaft 102 and make it integral to the rotation with the rotating body 111 .

The rotating body 111 comprises a semi-cylindrical portion I l la and a central protrusion 111b radially extending in a symmetrical manner with respect to a transverse axis B, perpendicular to the axis A, of the semi-cylindrical portion I l la . Advantageously, the diametrical edges 111c of the semi- cylindrical portion I l la are bevelled and the diametrical edges l l ld of the central portion 111b are bevelled .

The decoupling mechanism 110 further comprises engaging means configured to make the plate 107 integral with the rotating body 111 . Preferably, such engaging means comprise at least one pin 113 configured to integrally insert within an opening 114 obtained in the semi-cylindrical portion I l la and within an opening 114 obtained in the plate 107 , in a rotationally free manner with respect thereto .

The decoupling mechanism 110 further comprises a pair of actuator elements 115 , preferably shaped as axially symmetric elements such as cylinders , configured to be housed in respective openings 116 made on the plate 107 and extending within the space 106 beside the central portion 111b of the rotating body 111 .

The decoupling mechanism 110 further comprises locking means 118 housed in the space 106 and in particular circumferentially comprised between the actuator elements 115 and radially above the central portion 111b .

In particular, the locking means 118 comprise a pair of rotating elements 119 , such as cylindrical pins , and elastic means 120 operatively interposed between the rotating elements 119 . In particular, the rotating elements 119 are arranged in contact with the tubular portion 101b and the central portion 111b, between the edges l l ld of the latter advantageously symmetrically with respect to the axis B .

In particular, in circumferential direction with respect to the axis A, each rotating element 119 is spaced apart by a distance a with respect to an actuator element 115 . Therefore , i f necessary, before contacting the rotating element 119 , the actuator element 115 can circumferentially move for a short angular distance . In particular, the distance a is approximately 0 . 1 mm .

The elastic means 120 are configured to impart an opposite force along a direction perpendicular to the axes A and B of the rotating elements 119 when one of the latter acts on the elastic means 120 .

Advantageously, the semi-cylindrical portion 101a o f the rotating body 101 is axially separated along the axis A from the rotating body 111 by means o f sliding support means 121 such as a friction plate .

Conveniently, the tubular portion 101b of the housing 101 is axially spaced apart so as not to be in contact with the plate 107 .

The operation of the embodiment of the above-described electromechanical drive system is the following .

As is illustrated in Figure 2 , during an autopilot operation condition, the torque is supplied by the electric machine 3 by means of control of the electronic unit 4 . The latter adj usts the torque to be supplied based on the inputs provided by the operating elements 6 of the aircraft and in control , for example in closed loop , by means of the data found by the sensor means 5 . The torque supplied by the electric machine 3 , after passing by means of the transmission assembly 7 , passes by means of the two-way transmission 8 . In this case , the clutch assembly 9 is not activated and the torque passes directly to the transmission shaft 2 .

In the opposite case , illustrated in Figure 3 and relating to a manual operation condition, the torque is supplied directly, by means of manual commands not illustrated, to the transmission shaft 2 . Such torque passes to the two-way transmission 8 and here the clutch assembly 9 is activated and absorbs part of the torque thus generating on the actuations of the transmi ssion shaft 2 a feeling of passive resistance perceivable by the pilot , otherwise called reversibility load .

I f necessary, in the setting step, such resistance can be adj usted by means of the adj usting means 12 making the system versatile for numerous application fields .

In case of sei zure of the two-way transmission 8 or of the transmission assembly 7 which would prevent the rotation of the transmission shaft , the safety devices 11 break the transmission shaft 2 and allow the relative rotation with respect to the axis A of the third portion 2. ' ' ' thereof , i . e . a purely manual control thereof .

Referring to the operation of the two-way transmission rotation 8 , in the autopilot operation configuration with the motion act coming from the electric machine 3 , the torque is imparted by the plate 107 and thus to the pin 113 . The actuator pins 115 , consequently placed in rotation by the plate 107 , exceed the distance a and in contact with the rotating elements 119 move them with respect to the outer surface of the portion 111b of the rotating body 111 and to the housing 101 , allowing the relative rotation of the rotating body 111 within the space 106 of the housing 101 .

In this manner, the entire decoupling mechanism is made to rotate around the axis A with respect to the housing 101 , kept locked to the rotation by the elements of the clutch assembly 9 . Consequently, the movable portion 9 ' of the clutch assembly 9 is not actuated . The rotating body 111 thus drags in rotation the rotating shaft 102 transmitting the torque coming from the electric machine 3 by means of the coupling made in the opening 112 .

On the other hand, in the manual mode operation configuration, the torque is imparted by the rotating shaft 102 which is connected by means of the opening 112 to the rotating body 111 . Owing to the presence of the locking means 118 , the rotating body 111 is now integral with the housing 101 . In particular, such coupling is made possible by the contact between the central portion 111b and the rotating elements 119 which engage with respect to one another in contact with the housing 101b . Therefore , the housing 101 will be forced to rotate dragging therewith the movable portion 9 ' of the clutch assembly 9 generating a resistant torque . At the same time , the rotating body 111 dragged by the rotating shaft 102 cooperates through the pin 113 in dragging therewith the plate 107 and thus supplying torque to the transmission assembly 7 towards the electric machine 3 .

Based on the foregoing, the advantages of an electromechanical drive system according to the invention are evident .

Thanks to the illustrated electromechanical drive system it is poss ible to control in an optimised manner parts of an aircraft without using known trim actuators or fixed spring mechanisms or integrated versions of the latter with the addition of further active elements such as electrochemical machines intended to manage the exclusiveness of each function which they must satis fy, which entail additional weights and electrical consumptions .

In fact , the management of the reversibility load takes place in a completely automatic manner exploiting the decoupling mechanism 110 , without the use of electromechanical machines aimed at actively managing the load path change .

In this manner, the number of the elements used is reduced and thus bulks and production costs , as well as costs for the management and maintenance of the parts .

Still , thanks to the braking torque adj ustable by means of the compression means , it is possible to adj ust the feeling perceived by the pilot during the manual control of the drive system, ensuring the versatility of the actuation system .

Finally, it is clear that modi fications and variations can be made to the electromechanical drive system according to the present invention, which anyway do not depart from the scope of protection defined by the claims . For example , it is clear that the control of the electric machine and the sensor means used for such purpose can be of various type .

Also , the transmission assembly and the clutch device can be manufactured according to design requirements .

Furthermore , the two-way transmission 8 can be manufactured in a di f ferent manner . For example , the pin 113 can be replaced by a tongue or by more locking pins .

Still , the elastic means 120 can be replaced by a deformable and compressible element such as a polymeric support .

Likewise , the rotating elements 119 could be replaced by balls or other rotating elements .

Still , the angular position of the pins 115 can be varied according to the design requirements .

Still , bushings and other friction contact elements can be replaced by mechanically equivalent elements such as bearings or layers of lubricant .