EP0628783B1 - Actuation system for an aerodynamic control surface and aircraft steering system - Google Patents

Description

The present invention relates to an actuation system for aerodynamic control, as well as systems for the piloting of aircraft piloted in couple by control surfaces aerodynamic, comprising at least one such actuation system.

We know that the piloting of aircraft, in particular guided bombs or missiles, via aerodynamic control surfaces presupposes, to be precise, that the actuation systems of these aerodynamic control surfaces have well-defined properties. The reliability of these actuation systems, in particular, must be extremely high, especially when intended for military applications where any inaccuracy in piloting may have irreversible consequences. In this in fact, said actuation systems must, in particular, achieve performance in torque and time very high response.

The object of the present invention is to provide a system simple to operate, inexpensive and with very low aging, who is likely to meet the requirements previously mentioned.

• une bobine électromagnétique supplémentaire agencée sur ledit support fixe, en regard de ladite bobine électromagnétique citée en premier ;
• une palette mobile dont l'une des extrémités est fixée élastiquement audit support fixe, et dont l'autre extrémité est disposée entre lesdites bobines et est susceptible d'être attirée par chacune desdites bobines, de sorte que les deux positions actives et stables sont opposées l'une de l'autre par rapport à une position neutre ; et
• un élément mobile solidaire de ladite palette et portant ladite gouverne aérodynamique.

To this end, according to the invention, the actuation system for bringing an aerodynamic control surface into one or the other of two active and stable positions, said aerodynamic control surface being rotatably mounted on a fixed support and said system comprising a coil electromagnetic arranged on said fixed support to rotate said aerodynamic control surface against the action of elastic means, is characterized in that it comprises:

• an additional electromagnetic coil arranged on said fixed support, opposite said electromagnetic coil cited first;
• a movable pallet, one end of which is fixed elastically to said fixed support, and the other end of which is disposed between said coils and is capable of being attracted by each of said coils, so that the two active and stable positions are opposite from each other with respect to a neutral position; and
• a mobile element integral with said pallet and carrying said aerodynamic control surface.

Thus, thanks to the invention, the switching of the control surface aerodynamics of one of its stable active positions at the other is obtained simply by activating said electromagnetic coils, causing displacement of the movable pallet causing the switching of said aerodynamic control.

It will be noted that the document GB-A-1 057 863, the description of which forms the basis of the preamble of independent claim 1, describes a system actuation to bring an aerodynamic control surface into either of two active and stable positions, said aerodynamic control surface being rotatably mounted on a fixed support and said system comprising a single coil electromagnetic associated with said control surface, arranged on said fixed support and acting directly on said rudder (without interposition of pallet) to make it turn against the action of a spring, so that said control surface can take (exclusively, without position neutral) either of two extreme positions.

It will be noted that the elements constituting said system actuation according to the present invention are few numerous and of limited cost. Therefore, on the one hand the manufacturing price of the actuation system in accordance with the invention is small and, on the other hand, the volume of the actuation system is extremely small, which is very advantageous for its use on aircraft of small size, for example light missiles.

Advantageously, said movable element is constituted a rotating shaft and said movable pallet is fixed to the support by means of a spring leaf.

It will further be noted that, thanks to the use of said leaf spring and said electromagnetic coils, said actuation system according to the invention has high performance in terms of torque and response time.

Preferably, the neutral position of the control surface corresponds at the middle position of said pallet between said electromagnetic coils and this middle position of the pallet is defined by the rest position of said blade spring. To communicate to this middle position of the pallet, the appropriate rigidity, it is advantageous that, in neutral position of the control surface, said movable pallet and said leaf spring are orthogonal.

The present invention also relates to a system for piloting of an aircraft piloted in couple by at least two aerodynamic control surfaces, said control system comprising at least one actuation system like the one described previously.

The invention relates, more particularly, to a system for piloting an aircraft in autorotation comprising two aerodynamic control surfaces arranged symmetrically with respect to to the body of the latter. This steering system can in particular be used on multi-mission and anti-aircraft missiles light, characterized by high speed and a low mass after launch. Steering in efficient torque only requires control surfaces aerodynamics of reduced size.

Each of said aerodynamic control surfaces can be actuated by an individual actuation system in accordance with the invention and said aerodynamic control surfaces are controlled, synchronously, symmetrically with respect to to the body of the aircraft, by the simultaneous activation of a coil of each of said individual actuation systems.

As a variant, said control surfaces are actuated by a common actuation system, said actuation system common with identical additional mobile element said movable and integral element of said pallet in a symmetrical position with respect to that of said element mobile, said mobile element carrying one of said aerodynamic control surfaces and said additional mobile element carrying the other of said aerodynamic control surfaces.

This control system is particularly suitable for very small aircraft, especially mini missiles, whose reduced volume does not allow the arrangement several actuation systems, including control surfaces aerodynamics of restricted surface are subjected to relatively low forces and can thus be operated by a single actuation system.

Control systems, with one or two actuation systems, such as those described above, and comprising two aerodynamic control surfaces with two stable positions each, actuated symmetrically synchronously, are susceptible to take either of two positions of steering, depending on the common stable position in which are said aerodynamic control surfaces.

• dans l'une desdites positions de pilotage pendant une durée correspondant à un angle 2S d'un cercle représentant la durée d'un tour de rotation de l'aéronef ; et
• dans l'autre position de pilotage pendant le reste dudit tour de rotation, l'angle 2S vérifiant la relation |sinS|=(π/2f).F1 et comportant comme bissectrice ladite direction définie.

According to the invention, when the modulus of the piloting force is equal to f in each of said two piloting positions, said piloting system is remarkable in that, in order to obtain on an aircraft rotation turn an average force of F1 module steering directed in a defined direction, it is successively switched:

• in one of said piloting positions for a duration corresponding to an angle 2S of a circle representing the duration of a rotation turn of the aircraft; and
• in the other piloting position during the remainder of said rotation, the angle 2S verifying the relationship | sinS | = (π / 2f) .F1 and comprising said defined direction as bisector.

Thus, the desired steering force is easily obtained and this simply by putting the steering system, for respective periods of varying length, in either of said driving positions. For example, to obtain maximum average F1 driving force of value 2f / π, it suffices to put said system, during a half-turn of rotation, in one of said positions of piloting, and during the other half-turn of rotation, in the other steering position, so that S = π / 2.

However, the previous switching mode has a disadvantage when looking for a driving force very weak. Indeed, the actuation system allowing the switching has a time threshold, corresponding to its response time. Therefore, it is impossible obtain a 2S angle corresponding to a duration less than this time threshold.

• dans l'une desdites positions de pilotage pendant deux périodes non successives correspondant respectivement à deux angles 2S1 et 2S2 d'un cercle représentant la durée d'un tour de rotation de l'aéronef ; et
• dans l'autre position de pilotage pendant le reste dudit tour de rotation, lesdits angles S1 et S2 étant opposés, comportant comme même bissectrice ladite direction définie et vérifiant la relation |sinS1-sinS2|=(π/2f).F2.

Advantageously, in order to remedy this drawback and to obtain, on a rotation of the aircraft, an average piloting force of module F2 directed in a defined direction, said piloting system is successively switched:

• in one of said piloting positions during two non-successive periods corresponding respectively to two angles 2S1 and 2S2 of a circle representing the duration of a rotation turn of the aircraft; and
• in the other piloting position during the remainder of said turn of rotation, said angles S1 and S2 being opposite, comprising as said bisector said defined direction and verifying the relationship | sinS1-sinS2 | = (π / 2f) .F2.

Thus, it is possible to obtain driving forces of module as low as desired, minimizing the difference between angles S1 and S2. This steering system therefore makes it possible to obtain forces of very low steering than large steering forces, and is particularly well suited to missiles multi-missions.

The present invention also relates to a system for piloting an aircraft with four aerodynamic control surfaces arranged uniformly around said aircraft spaced.

According to the invention, such a control system, which is particularly suitable for a large air-to-ground missile or a planing bomb with limited maneuver, is remarkable in that that the opposite control surfaces are identical and in that each of them is actuated by a system individual actuation according to the invention.

• un système de guidage, déterminant les ordres de roulis, tangage et lacet ; et
• un calculateur, recevant lesdits ordres, et déterminant l'activation des différentes bobines électromagnétiques.

Advantageously, said control system is provided with a control device intended to control the activation of the electromagnetic coils of the various individual actuation systems, comprising:

• a guidance system, determining the roll, pitch and yaw orders; and
• a computer, receiving said orders, and determining the activation of the various electromagnetic coils.

The figures in the accompanying drawing will make it clear how the invention can be realized. In these figures, references identical denote similar elements.

Figure 1 is a partial perspective view of a actuation system according to the invention.

Figure 2 shows, schematically, the piloting an aircraft, comprising two aerodynamic control surfaces operated by two separate actuation systems.

Figure 3 shows, schematically, the piloting an aircraft, comprising two aerodynamic control surfaces operated by the same actuation system.

Figure 4 illustrates the generation of a lateral force of piloting, according to a first piloting principle.

Figure 5 illustrates the generation of a lateral force of piloting, according to a second piloting principle.

Figure 6 is the block diagram of the control system of an aircraft comprising four aerodynamic control surfaces.

Note that, in Figures 1, 2, 3 and 6, the control surfaces are represented schematically in the form of pallets.

The actuation system 1, according to the invention and shown in Figure 1, is intended to actuate a aerodynamic control surface G partially shown and schematically in this figure.

According to the invention, said actuation system 1 has two identical electromagnetic coils A and B arranged one opposite the other on a fixed support 2, which can be attached to the body of an aircraft (not shown). Said coils A and B can be activated independently, via a control system (not shown).

Said actuation system 1 also includes a movable pallet P fixed elastically by one of its ends 4 on the fixed support 2, via a spring leaf 5 integral with both said end 4 and of said support 2. For this purpose, said blade of spring 5 is embedded by its opposite ends, at the times in said fixed support 2 and in the end 4 of the pallet P. The other (free) end 6 of pallet P is disposed between said coils A and B. When the coils A and B are not activated, the moving paddle P is located in a median plane π, partially shown in lines mixed in FIG. 1, equidistant from said coils A and B, parallel to the respective internal faces 8 and 9 of these last and orthogonal to the leaf spring 5.

The activation of one or the other of said coils causes the displacement of the pallet P, by rotation around an axis X-X defined by the intersection of the median plane n and the blade spring 5, so that the free end 6 of the pallet P comes into contact with the coil which is activated and remains in this position as long as this coil is activated.

In addition, a mobile element, in this case a tree rotary 7, is secured laterally to said pallet P at level of the end 4 of the latter, coaxially with the X-X axis.

Said rotary shaft 7 carries the aerodynamic control surface G arranged parallel to the pallet P and shown in solid lines in its neutral position in Figure 1.

Consequently, said control surface G is integral with the displacement of the free end 6 of the pallet P between the coils A and B.

• dans la position active stable 10 qui fait un angle +Θ par rapport à la position neutre, lorsque la bobine A est activée et que l'extrémité libre 6 de la palette P se trouve au contact de celle-ci ; et
• dans la position active stable 11 qui fait un angle -Θ par rapport à la position neutre, lorsque la bobine B est activée et que l'extrémité libre 6 se trouve au contact de cette dernière.

Thus, in accordance with the invention, said aerodynamic control surface G can be brought into one of two active, stable and opposite positions 10 and 11, partially shown in broken lines in FIG. 1, namely:

• in the stable active position 10 which forms an angle + Θ relative to the neutral position, when the coil A is activated and the free end 6 of the pallet P is in contact with the latter; and
• in the stable active position 11 which forms an angle -Θ relative to the neutral position, when the coil B is activated and the free end 6 is in contact with the latter.

Switching the aerodynamic control surface G of one of its active positions stable to each other is therefore obtained by reversing the activation of the coils.

The actuation system 1 according to the invention can be used in a piloting system 12 of an aircraft 14 in autorotation around its Y-Y axis, which is shown on Figure 2, partially and schematically, the body 13. Said aircraft 14 is piloted in pairs by two control surfaces aerodynamics G1 and G2 identical, arranged so symmetrical about the Y-Y axis. Each of said control surfaces aerodynamic G1 and G2 is powered by a system actuation 1 individual, and this synchronously, so that said control surfaces are always in a same piloting plan. For this purpose, the coils A of each of the two actuation systems 1 are activated at the same time time. The same is true for coils B.

• une première position de pilotage, lorsque les palettes P sont au contact des bobines A et qu'alors les gouvernes aérodynamiques G1 et G2 se trouvent respectivement dans des positions 15 et 16 partiellement représentées en traits interrompus sur la figure 2 et faisant un angle +Θ avec la position médiane représentée ; et
• une seconde position de pilotage, lorsque les palettes P sont au contact des bobines B et qu'alors les gouvernes aérodynamiques G1 et G2 se trouvent respectivement dans des positions 17 et 18 partiellement représentées en traits interrompus et faisant un angle -Θ avec la position médiane représentée.

Thus, the piloting system 12 can take two different piloting positions, namely:

• a first piloting position, when the paddles P are in contact with the coils A and when the aerodynamic control surfaces G1 and G2 are respectively in positions 15 and 16 partially represented in broken lines in FIG. 2 and making an angle + Θ with the middle position shown; and
• a second piloting position, when the paddles P are in contact with the coils B and when the aerodynamic control surfaces G1 and G2 are respectively in positions 17 and 18 partially represented in broken lines and making an angle -Θ with the middle position represented.

Depending on whether the control system 12 is in one or the other of said riding positions, it generates two piloting forces of the same module, directed according to the same Z-Z direction (perpendicular to X-X and Y-Y directions) but in the opposite direction.

In another embodiment, as shown in the Figure 3, the control system 20 comprises a single system actuation 1 to actuate the two aerodynamic control surfaces G1 and G2.

• une première position de pilotage, lorsque la palette P est au contact de la bobine A et que les gouvernes aérodynamiques G1 et G2 se trouvent respectivement dans les positions 15 et 16 ; et
• une seconde position de pilotage, lorsque la palette P est au contact de la bobine B et que les gouvernes aérodynamiques G1 et G2 se trouvent alors respectivement dans les positions 17 et 18.

To this end, the actuation system 1 comprises two opposite shafts 7, arranged laterally on the pallet P, on either side of the spring leaf 5, in the direction XX, and carrying respectively said aerodynamic control surfaces G1 and G2 . Like the piloting system 12 in FIG. 2, the piloting system 20 can take two different piloting positions:

• a first piloting position, when the paddle P is in contact with the coil A and when the aerodynamic control surfaces G1 and G2 are respectively in positions 15 and 16; and
• a second piloting position, when the paddle P is in contact with the coil B and the aerodynamic control surfaces G1 and G2 are then respectively in positions 17 and 18.

The piloting of the aircraft 14 in autorotation is carried out in the same way for the two piloting systems 12 and 20 described above. To this end, on a rotation, the control system 12 or 20 is successively switched into its two control positions, thus generating at any time a control force of module f , of direction ZZ, and whose direction depends, at a given time, from the steering position used at that time.

According to a first piloting principle, as illustrated schematically in Figure 4, the control system 12 or 20 is maintained in a first piloting position for a period corresponding to an angle 2S of a circle C, representing the duration of one rotation of the aircraft, then is switched to the other driving position for the rest of the duration of said rotation.

Said first piloting position generates, at successive instants, on the circle C, along the arc of the circle defined by the angle 2S, radial forces of the same module f (as represented at points 21), while that the second piloting position generates piloting forces of the same module f but of opposite direction (as represented at points 22).

However, as the aircraft turns, these forces in opposite directions generated during rotation present on a turn of the additional effects so that we get, for a rotation, an average driving force F1 of module F1 = (2 / π) .f. | sinS | directed by the bisector Ox from the angle 2S.

Note, however, that this F1 driving force always remains greater than a minimum force. Indeed, the actuation system has a corresponding time threshold to its response time which depends, in particular, on the stiffness of the leaf spring 5, the resistance and the inductance of coils A and B and the inertia of the system actuation. Therefore, the angle S is always greater than an angle Smin, such that Smin = τ / 2 where  represents the speed of rotation of the aircraft and τ the time threshold of the actuation system, and therefore the driving force F1 is always greater than a minimum force Fmin = (2 / π) .f. | Sin (Smin) |.

According to a second piloting principle, as illustrated schematically in Figure 5, the control system 12 or 20 is switched to the same driving position for two durations corresponding respectively to two angles 2S1 and 2S2 on circle C and defined so that these angles 2S1 and 2S2 are opposite and have the same bisector L-L. The rest of the rotation, corresponding to two angles α and β identical, the control system is switched to the other riding position.

The driving forces generated on the angles 2S1 and 2S2, in an identical riding position, but for two opposite positions of the aircraft around its axis Y-Y, have opposite effects. The same is true of effects produced on the angles α and β. However, as said angles α and β are identical, the effects produced along their common bisector (not shown) cancel each other out, which is not the case for the angles 2S1 and 2S2 (when different, as shown). So, one obtains, on a rotation of the aircraft, a force piloting average F2, depending only on the angles S1 and S2, of module F2 = (2 / π) .f. | SinS1-sinS2 |, directed along the common bisector L-L of angles 2S1 and 2S2.

This second steering principle is particularly appropriate to obtain module driving forces F2 restricted, since it is possible to make the difference | sinS1-sinS2 | as low as desired, using angles S1 and S2 close to each other.

The actuation system 1 according to the invention can also be used in a control system 25, such as shown schematically in Figure 6, to control relatively heavy aircraft, such as a large one air-to-ground missile or a maneuvering planar bomb, through four G3 aerodynamic control surfaces, G4, G5 and G6.

Said aerodynamic control surfaces G3, G4, G5 and G6, actuated each by an individual actuation system 1, are arranged around the aircraft (not shown), being each time separated by 90 °, so that, on the one hand the aerodynamic control surfaces G3 and G5 which are identical and, on the other hand, the aerodynamic control surfaces G4 and G6 which are identical, are arranged symmetrically with respect to the axis of said aircraft.

The piloting of said aircraft is carried out by modifying the activation electromagnetic coils A and B of the different actuation systems 1, and therefore the position of the control surfaces corresponding aerodynamics.

• un système de guidage 27 déterminant les ordres de roulis, de tangage et de lacet ; et
• un calculateur 28, recevant lesdits ordres par l'intermédiaire d'une liaison 29, déterminant l'activation des bobines électromagnétiques A et B des systèmes d'actionnement 1 associés à chacune des gouvernes aérodynamiques G3, G4, G5 et G6, et commandant lesdites bobines A et B par l'intermédiaire de liaisons 30 à 33.

To this end, said control system 25 is provided with an on-board control device 26, comprising:

• a guidance system 27 determining the roll, pitch and yaw orders; and
• a computer 28, receiving said orders via a link 29, determining the activation of the electromagnetic coils A and B of the actuation systems 1 associated with each of the aerodynamic control surfaces G3, G4, G5 and G6, and controlling said coils A and B via links 30 to 33.

Claims (11)

1. Actuating system (1) for bringing an aerodynamic control surface (G) into one or other of two active and stable positions, the said aerodynamic control surface (G) being mounted so that it can rotate on a fixed support (2) and the said system including an electromagnetic coil (A or B) arranged on the said fixed support (2) so as to make the said aerodynamic control surface turn against the action of elastic means, characterized in that it includes:

   an additional electromagnetic coil (B or A) arranged on the said fixed support (2) facing the said first-mentioned electromagnetic coil (A or B);

   a mobile vane (P), one (4) of the ends of which is elastically attached to the said fixed support (2), and the other end (6) of which is arranged between the said coils (A,B) and can be attracted by each of the said coils so that the two active and stable positions are the opposite sides of a neutral position to one another; and

   a mobile part (7) integral with the said vane (P) and bearing the said aerodynamic control surface (G).
2. Actuating system according to Claim 1, characterized in that the said mobile part consists of a rotary shaft (7).
3. Actuating system according to one of Claims 1 or 2, characterized in that the said mobile vane (P) is elastically attached to the said support by means of a leaf spring (5).
4. Actuating system according to Claim 3, characterized in that when the control surface is in the neutral position, the said mobile vane (P) and the said leaf spring (5) are orthogonal.
5. System for steering an airborne vehicle steered using couple by at least two aerodynamic control surfaces (G1,G2,G3,G4,G5,G6), characterized in that it includes at least one actuating system (1) according to one of Claims 1 to 4.
6. System for steering an airborne vehicle which is autorotating, including two identical aerodynamic control surfaces (G1,G2) arranged symmetrically with respect to the body of the vehicle, according to Claim 5, characterized in that each of the said aerodynamic control surfaces (G1,G2) is actuated by an individual actuating system (1) and in that the said aerodynamic control surfaces (G1,G2) are controlled synchronously and symmetrically with respect to the body of the airborne vehicle by simultaneous activation of a coil of each of the said individual actuating systems.
7. System for steering an airborne vehicle which is autorotating, including two identical aerodynamic control surfaces (G1,G2) arranged symmetrically with respect to the body of the vehicle, according to Claim 5, characterized in that the said control surfaces (G1,G2) are actuated by a common actuating system (1), the said common actuating system (1) including an additional mobile part (7) identical to the said mobile part (7) and integral with the said vane in a position which is symmetric to the position of the said mobile part, the said mobile part bearing one of the said aerodynamic control surfaces, and the said additional mobile part bearing the other of the said aerodynamic control surfaces.
8. System according to either of Claims 6 or 7, for steering an airborne vehicle, including two aerodynamic control surfaces, each with two active and stable positions, which are actuated symmetrically and synchronously and, depending on the stable position in which they are lying, bring the said steering system into one of two steering positions, the modulus of the steering force being equal to f in each of the said steering positions, characterized in that in order to obtain, over one revolution of the airborne vehicle, a mean steering force of modulus F1 directed in a defined direction (Ox), it is switched in turn:

   into one of the said steering positions for a duration that corresponds to an angle 2S of a circle (C) representing the duration of one revolution of the airborne vehicle; and

   into the other steering position for the remainder of the said revolution, the angle 2S satisfying the relationship |sinS| = (π/2f).F1 and having as its bisector the said defined direction (Ox).
9. System according to either of Claims 6 or 7, for steering an airborne vehicle, including two aerodynamic control surfaces, each with two active and stable positions, which are actuated symmetrically and synchronously and, depending on the stable position in which they are lying, bring the said steering system into one of two steering positions, the modulus of the steering force being equal to f in each of the said steering positions, characterized in that in order to obtain, over one revolution of the airborne vehicle, a mean steering force of modulus F2 directed in a defined direction (L-L), it is switched in turn:

   into one of the said steering positions for two non-successive periods corresponding respectively to two angles 2S1 and 2S2 of a circle (C) representing the duration of a revolution of the airborne vehicle; and

   into the other steering position for the remainder of the said revolution, the said angles S1 and S2 being opposite angles, having as their common bisector the said defined direction (L-L) and satisfying the relationship |sinS1-sinS2| = (π/2f).F2.
10. System according to Claim 5, for steering an airborne vehicle, including four aerodynamic control surfaces (G3,G4,G5,G6) arranged so that they are uniformly spaced around the said airborne vehicle, characterized in that the control surfaces, in opposed pairs, are identical and in that each of the said control surfaces is actuated by an individual actuating system (1).
11. System for steering an airborne vehicle according to Claim 10, characterized in that it is equipped with a control device (26) intended to control the activation of the electromagnetic coils (A,B) of the various individual actuating systems, including:

    a guidance system (27), formulating the commands in roll, pitch and yaw; and

    a computer (28) receiving the said commands and determining the activation of various electromagnetic coils.

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