EP2573504B1 - System for piloting an aircraft using pairs of lateral nozzles - Google Patents

Description

The present invention relates to a system for controlling a flying machine, such as a missile or the like, using side gaseous jets.

It is known that, in order to steer a missile on a trajectory, especially when it must be subjected to sudden and large load factors, lateral jet control systems are used which are provided on board the missile and which are capable of be supplied with gas from either a main propellant gas generator or a specially designed gas generator.

Thus, it results in lateral gas jets generating transverse propulsive forces able to quickly and significantly alter the trajectory of the missile. We can make sure that the lines of action of such transverse forces pass through the center of gravity of the missile, or at least in the vicinity of this center of gravity, and we then say that the missile is piloted in force, the response time to the command being particularly fast. However, this is not an obligation and the lines of action of said transverse forces can pass at points of the missile axis different from the center of gravity. Said transverse forces then create, in a manner similar to conventional aerodynamic control surfaces, moments which make it possible to control the missile in attitude with respect to the center of gravity.

To modify the passage section of the gases passing through the lateral nozzles and thus act on the trajectory of the missile, the control systems also include movable shutter devices provided between the generator and the nozzles, and controlling the passage of the gases from the generator .

In the known embodiments, at each nozzle is associated a closure device comprising a shutter connected to the nozzle, and a motor member controlling the displacement of the shutter, so as to vary the passage section of the gas passing through the collar. the nozzle. Thus, these devices deliver, depending on their position, a thrust in a given direction (along the geometric axis of the nozzle concerned) and in one direction (depending on the outlet of the nozzle).

• du type tout ou rien, à modulation de poussée par largeur d'impulsion de type PWM (pulse width modulation) à actionnement de puissance pneumatique. La variation de la pression dans la ou les chambres d'un vérin pneumatique s'effectue grâce à des clapets pilotés par des électroaimants en tout ou rien (de 0 à la poussée maximale en un temps aussi court que possible, limité par la dynamique des électroaimants et du vérin d'actionnement de l'obturateur). Cependant, ce principe de fonctionnement simple induit, de facto, des chocs violents (de plusieurs dizaines de g) et des vibrations sur les structures et les équipements de l'engin à piloter et ne permet pas, de plus, une régulation précise de la poussée ; ou
• du type électromécanique, utilisant des moteurs électriques associés à un réducteur et/ou un dispositif de transformation de mouvement à vis pour piloter la position de l'obturateur. Ce type de dispositif à déplacement de 'pointeau' rectiligne, compte tenu des efforts et des puissances en jeu, ne permet pas d'obtenir des performances dynamiques élevées avec une masse et un encombrement raisonnable comparativement aux dispositifs pneumatiques précédents.

The shutter devices are, as a reminder, mainly:

• of the all-or-nothing type, PWM type pulse width modulation (pulse width modulation) with pneumatic power actuation. The variation of the pressure in the chamber or chambers of a pneumatic cylinder is achieved by valves controlled by electromagnets in all or nothing (from 0 to the maximum thrust in a time as short as possible, limited by the dynamics of electromagnets and actuator actuator shutter). However, this principle of simple operation induces, de facto, violent shocks (of several tens of g) and vibrations on the structures and equipment of the machine to be driven and does not allow, moreover, a precise regulation of the thrust; or
• electromechanical type, using electric motors associated with a gearbox and / or a screw motion transformation device for controlling the position of the shutter. This type of rectilinear 'needle' displacement device, taking into account the forces and powers involved, does not make it possible to obtain high dynamic performances with a mass and a reasonable bulk compared to the previous pneumatic devices.

These devices have disadvantages. Because they are associated respectively with the nozzles, this implies a complex implementation and a congestion accordingly. Functionally, the rectilinear displacement of a shutter to close more or less the neck of a nozzle acts certainly in a given direction (lace or pitch for example) but in the direction imposed by the nozzle. These devices also have the disadvantage of generating very significant efforts for the operation on the shutter. The possible balancing of efforts to reduce the power required, the setting and the motorization of a differential system is complex. In addition, it is necessary, in the case of an electromechanical solution, to transform the rotation of the motor into a rectilinear movement in a very unfavorable environment of hot gases.

It is known, moreover, by the patent FR 2 659 734 , a steering system of a missile by side gaseous jet whose nozzle closure device, four in number, two to two diametrically opposite, then comprises four rotary shutter valves distributing the gas flow of a propellant to powder in the four nozzles.

It is thus possible to obtain a modulable thrust in two perpendicular directions. The valves are coupled mechanically in pairs to ensure a constant flow in each pair of diametrically opposed nozzles (risk of explosion of the powder booster overpressure) and the shutters are actuated by pistons pneumatic cylinders powered by borrowing propellant gas and enslaved in position. Controlling the position of the shutters by hot gas pneumatic cylinders makes it possible to obtain excellent dynamic performance due to their very high mass power.

Although it is operational successfully, this system is however heavy, relatively complex and difficult to regulate, in particular, because of the need to mechanically connect two shutter devices, in this case the valves shutters which are in connection with two respective nozzles diametrically opposed to act in both directions of the same direction. It is also necessary to use refractory materials subjected to high pressures. In addition, when the powder propellant is ignited, there necessarily exists a transient moment of uncontrolled servocontrol due to the rise in pressure and to the random position of the various components of the device (shutter, control ball). The mechanical connection for coupling the shutters of the valves is, in addition, a source of significant friction that adversely affect the quality of the servo and force over-size the power of the actuators.

It is also known from the document WO 96/13694 , which forms a starting point for claim 1, a launching and steering system of flying machines, provided with pairs of opposing nozzles controllable by shutter devices and located in the rear part of the flying machine for place it, after launch from the ground, towards the target, in the path.

The present invention aims to overcome the above disadvantages and relates to a steering system of a flying vehicle with side jets whose design is compact and modular, and is simplified to, in particular, to obtain a enslavement of a thrust level in both directions of a given direction.

For this purpose, the system for steering a flying machine to a target along its trajectory, such as a missile and the like, using side gaseous jets, comprises a gas generator capable of be connected to lateral nozzles via movable shutter devices, controlling the passage of the gases from the generator through said nozzles, the latter being associated in pairs so that the nozzles of each pair are aligned on the same axis and arranged in opposition to one another, with, between the two aligned nozzles of the pair, a single controllable shutter device in connection with said generator and adapted to control the passage of gases through said nozzles in both meaning, the pairs of nozzles being contained in a plane perpendicular to the axis of the machine, each closure device being such that it allows to vary the gas passage sections from the generator through the nozzles, so inverse of each other, each closure device being of the rotary shutter type, the system being remarkable in that said plane containing the pairs of nozzles passes through the center of gravity of the machine, and by the each shutter device further comprises a controllable motor orally receiving the proportional operating commands and connected to the shutter to move it and continuously vary the passage sections of the gas passing through the nozzles.

Thus, thanks to the invention, the same shutter device controls two nozzles and makes it possible to act in both directions of the same direction imposed by the pair of opposed and aligned nozzles, so as to obtain the servo-control of a thrust level in both directions in the direction of the pair of nozzles, and continuously modulate the thrust in this common direction.

The system thus overcomes the prior disadvantages imposing a nozzle closure device with action only in the direction of the nozzle concerned, and eliminates the mechanical connections between the valves, simplifying the realization of the system.

For example, two pairs of nozzles are arranged diametrically opposite to each other in a plane perpendicular to the longitudinal axis of the machine. Thus, one can drive the machine along the axes of roll and yaw or roll and pitch. The operation of the pairs of nozzles can be carried out independently of one another or simultaneously with the closure devices of the two pairs in the same position or in different positions so that the machine takes the most appropriate trajectory at each moment of the flight by combining different movements if necessary.

In another preferred example, four pairs of nozzles are arranged regularly spaced from each other, in a plane perpendicular to the axis of the machine, the four pairs being diametrically opposed two by two. The driving force of the machine can be done according to the axes of roll, yaw and pitch with operation as indicated above. Whatever the examples, the control of the machine to the target along the path, which may vary.

Preferably, the control system comprises two sets of aligned pairs of nozzles and in opposition, said sets being provided in planes parallel to each other and perpendicular to the longitudinal axis of the machine, one of said planes passing through the center gravity of said craft. Thus, with such an arrangement, it can drive the machine force by printing transverse forces through the set of pairs of nozzles passing through the center of gravity, or the attitude control of the machine along the axes of roll, pitch and yaw, through the other set.

More particularly, the pairs of nozzles, each of which is associated with a single closure device, are located at the periphery of the outer cylindrical body of the machine and surround the gas generator in fluid communication therewith.

Each shutter device is of the rotary shutter type for the variation of the passage sections of the gases from the generator through the nozzles, in an inverse manner to one another.

For example, each closure device comprises an internal passage body in which the rotary shutter is received and which has two diametrically opposite openings respectively connected to the necks of the aligned nozzle in opposition, and an opening connected to the gas generator.

Each shutter can occupy a neutral position for which the openings communicate with each other, allowing the gases, when the generator is a block of powder ensuring moreover the axial thrust of the machine, to flow at each instant with a constant flow through pairs of nozzles, avoiding the risk of overpressure. In case the generator uses propellants of the liquid type, the shutters then occupy a neutral position for which they close the openings connected to the generator.

• Les figures du dessin annexé feront bien comprendre comment l'invention peut être réalisée. Sur ces figures, des références identiques désignent des éléments semblables.
• La figure 1 est une vue schématique d'un engin volant tel qu'un missile avec un système de pilotage conforme à l'invention.
• La figure 2 montre un exemple de réalisation du système de pilotage comprenant, dans ce cas, deux ensembles de tuyères latérales à dispositifs d'obturation associés.
• La figure 3 est une vue transversale de l'un des ensembles de tuyères latérales montrant l'agencement de celles-ci.
• La figure 4 représente l'obturateur d'un dispositif d'obturation pilotant la paire de tuyères latérales associées, alignées en opposition.
• Les figures 5 et 6 représentent un dispositif d'obturation avec deux exemples de montage de l'organe moteur commandant l'obturateur.

Furthermore, each closure device further comprises a controllable motor member receiving the proportional operating commands and connected to the shutter to move it and continuously vary the passage sections of the gas passing through the nozzles. Said motor member is preferably a torque motor connected in parallel or coaxially with a rotary shaft carrying said shutter by means of a connecting mechanism.

• The figures of the appended drawing will make it clear how the invention can be realized. In these figures, identical references designate similar elements.
• The figure 1 is a schematic view of a flying machine such as a missile with a control system according to the invention.
• The figure 2 shows an exemplary embodiment of the control system comprising, in this case, two sets of side nozzles with associated closure devices.
• The figure 3 is a transverse view of one of the sets of lateral nozzles showing the arrangement thereof.
• The figure 4 represents the shutter of a shutter device driving the pair of associated lateral nozzles, aligned in opposition.
• The Figures 5 and 6 represent a shutter device with two mounting examples of the motor member controlling the shutter.

The flying machine such as the missile 1, schematized on the figure 1 , comprises an elongated cylindrical body 2 of longitudinal axis A ending, at the rear, by empennages 3 for example four in number, two by two diametrically opposite, and optionally provided with non-illustrated control surfaces. The gaseous jet leaving an axial nozzle 4 (in dotted line), is symbolized by an arrow F and is issued in the usual manner from a gas generator 5 internal to the body 2 of the missile and printing the thrust to the missile 1.

In the vicinity of the center of gravity G of the missile 1 is provided in the cylindrical body 2, a control system 6 which, as shown by the Figures 1 to 3 , consists of lateral nozzles 7, controllable shutter devices 8 and a gas generator. In this example, the generator is the gas generator providing the axial thrust to the missile, but it goes without saying that the generator of the system could be different from the main generator. The control system 6 thus arranged makes it possible, as will be seen below, to act on the attitude of the missile 1 along the axes of roll, yaw and pitch (see the Oxyz reference, figure 1 ), and to apply forces in y and z passing through the center of gravity G. It is therefore of the driving type in force.

The gas generator 5 of the system 6 and the missile 1 is constituted, as shown in FIG. figure 2 , a block of solid powder 10 housed in a casing or cylindrical can 11 which is reported in a usual manner inside the cylindrical body of the missile.

In this nonlimiting exemplary embodiment, the system 6 comprises two sets E1, E2 of lateral nozzles 7, the assemblies having the same number of nozzles and being arranged in two parallel planes PL1 and PL2, perpendicular to the longitudinal axis A of the missile (x axis of the repository).

The control system 6 of the invention consists in pairing pairs of lateral nozzles 7 in opposition to one another, so that the two nozzles of each pair are controllable from the same closure device 8 between them. For this purpose, the two lateral nozzles 7 of each pair are aligned on the same axis A1 ( Figures 3 and 4 ) and are arranged in opposition to each other with the collars 12 of these nozzles facing one another and fixed to the common closure device 8, in the center of the two nozzles.

As we see on the figures 2 and 3 , each set E1, E2 comprises, in this example, four identical pairs P1, P2, P3, P4 of two lateral and opposite nozzles 7, the four pairs being diametrically opposite in pairs and located near the periphery of the cylindrical body 2 of the missile 1. Thus, in this example, two pairs are parallel to the y axis of the frame and two other pairs are parallel to the z axis. The two sets E1 and E2 then comprise sixteen nozzles 7 forming eight double nozzles or pairs of nozzles.

Moreover, still in this example, the plane PL1 of the first set E1 of four pairs of opposite lateral nozzles passes at least substantially through the center of gravity G of the missile 1, so as to ensure the driving force thereof. As for the plane PL2 of the second set E2, it is shifted parallel to the plane PL1 and the pairs of lateral nozzles ensure in particular the steering attitude of the missile.

Of course, the operation of the sets E1, E2 can be performed independently of one another or simultaneously, with the actuation, by the control of the shutter devices concerned 8, of one or more pairs P1, P2, P3, P4 lateral nozzles 7 whatever they are. The control system 6 is also not limited to this specific arrangement of two planes of four pairs of opposing nozzles each. At least one pair of opposite lateral nozzles 7, controllable by a common closure device 8 and contained in a plane perpendicular to the longitudinal axis of the missile, is sufficient to drive the missile in both directions in one and the same direction. given by the common alignment axis A1 of the nozzles in opposition. Of course, it is preferable to have at least two pairs of nozzles, arranged symmetrically with respect to the axis of the missile to avoid parasitic effects if only one pair was present.

As we see more particularly with regard to the figure 4 , the side walls 1 3 delimiting the two lateral nozzles 7 aligned in opposition to the pair shown P1 are attached to a body 14 of the controllable shutter device 8, common to both nozzles, by any suitable means (screwing, welding, etc.). .). In the body 14 is formed an axial passage 15 in which is housed the shutter proper 16 which is of the rotary type, rotating about an axis A2 parallel to the axis A of the missile and, therefore, perpendicular to the axis common A1 aligned nozzles.

This internal passage 15 has a cylindrical shape for the rotation of the shutter and acts as an intermediate chamber between the generator 5 and the two lateral nozzles 7, with the shutter 16 which allows to adjust, according to its position and in a reverse manner. one of the other, the gas passage section from the generator 5, with a constant flow rate in the case of a powder generator, through the necks 12 of the nozzles, and consequently, to act on the trajectory missile.

For this, to ensure fluid communication between the passage or internal chamber 15 of the body 14 and the necks 12 of the nozzles 7 aligned in opposition, two openings 17 are made, diametrically opposite, in the body and open, once the nozzles integral with the body, respectively facing the necks of said nozzles.

And, to ensure fluid communication between the internal passage 15 of the body of the device 8 and the powder block 10 of the gas generator 5, a radial opening 18 is provided in the body, perpendicularly, on the one hand, to the axis common A1 thrusters 7 and diametrical openings 17 and, secondly, to the axis of rotation A2 of the shutter, that is to say the axial passage 15 of the body 14.

In particular, the shutter shown 16 has a shape suitable for allowing the free passage of the gases of the generator 5 when the block of powder 10 is initiated, and vary the section of passage of the gases through the openings 17 towards the neck of the nozzles opposite 7 of the pair in question P1, as a result of the control of the shutter. It thus allows the modulation of the thrust by the position it occupies. In this example, the shutter 16 substantially covers 180 ° of the internal passage 15 and is in the form of an angular sector half-crown (or bean) provided on a rotary shaft 19 about the axis A2. The shutter 16 and the shaft 19 are preferably made in one and the same piece.

So, in the position illustrated on the figure 4 a position qualified as neutral, for which no piloting order is sent towards this pair P1 opposing lateral nozzles 7, the shutter 16 obstructs half of the two diametrical openings 17 of the body 14 giving in the necks 12 of the nozzles (in the case where the generator is liquid propellant, the angular section of the shutter will be of the order of 240 ° to simultaneously close the necks of the two nozzles). The operation of the system 6 and its devices 8 will be described below.

The rotation control of the shaft 19 of the shutter of the device concerned 8 is carried out by a motor member 20 which is arranged in the two embodiments illustrated respectively on the Figures 5 and 6 , parallel to the axis of rotation A2 of the shaft 19 ( figure 5 ), or coaxially with its A2 axis ( figure 6 ).

In the embodiment shown on the figures 2 and 5 in particular, the drive member 20 of each closure device 8 common to the pair of nozzles concerned P1, P2, P3, P4, is offset parallel to the shutter 16. To ensure the transmission of motion, the 21 of the motor member and the shaft 19 of the shutter are connected to each other by a connecting mechanism, such as a toothed sector 23 forming a reduction stage between the pinion of the shaft of the output 21 and the shaft 19 of the body 14. A common housing 24 joins, moreover, the drive member 20 to the body 14 of the device.

In addition, to minimize the frictional moments, the shaft 1 9 of the shutter is mounted on needle bearings 25 provided between the body 14 of the device and the shaft 19, respectively on either side of the shutter 16. An O-ring seal 26 is, moreover, provided between the body and the shaft protecting the inside of the closure device 8 of the external medium (heat flows). And a thrust bearing 27 is also disposed between the support 28 of the seal and a shoulder 29 formed on the shaft 19 of the shutter.

In another achievement illustrated on the figure 6 , the motor member 20 is coaxial with the closure device 8. For this, a planetary gear 30 or other suitable reduction mechanism is attached to the output of the drive member and is connected by its shaft 21 to the 19 shutter shaft. A cylindrical casing 31 also associates the gearbox 30 with the body 14 of the device. Again, the rotary shaft 19 is mounted relative to the fixed body 14 on needle bearings 25 and axial thrust ball 27. The seal 26 is also provided.

The reduction ratio must, however, remain low enough to keep the device a high dynamic (speed and acceleration) compatible with the steering of the missile.

Whatever the embodiment adopted, thanks to the mounting of bearings and thrust ball bearings, the motor member 20 may be a simple electric torque motor, of compact size and providing sufficient torque to drive the shutter. To this torque motor is advantageously associated, at the rear of the latter, a housing 32 enclosing appropriate power and servo electronics, not shown, for the operation of each shutter device 8 to be controlled. The drive member is slaved into position and incorporates an angular position sensor or other suitable device. The accurate knowledge of the position of each shutter by the feedback sensor and a measurement of the pressure of the propulsion gases makes it possible to determine, in a relatively precise manner, the thrust level (amplitude and sign) as a function of the commanded position. shutter.

Note also, the particularly simple embodiment of the common closure device 8, both from the structural point of view (assembly) and functional (adjustment and value of the angle of the angular sector of the shutter necessary for opening and closing). closure of the associated nozzles).

In the system according to the invention is used a rotary shutter. One could consider a shutter movable in translation, but this would imply a more complex assembly.

The operation of the control system 6 equipping such a missile 1 is as follows.

It is assumed that the missile follows the imposed trajectory, the powder block 10 of the generator 5 being in the process of combustion providing the axial thrust F to the missile, without intervention of the steering system.

In this configuration, the shutters 16 of the shutter devices 8 associated with the pairs P1, P2, P3, P4 of opposite nozzles 7 all occupy a neutral position as illustrated in FIGS. Figures 3 and 4 . That is to say, the sections of the necks 12 of the nozzles through which the gaseous side jets pass J after having passed through the opening 18, the passage or chamber 15 and the two diametrical openings 17 of each device are equal. Thus, the outgoing jets J, in the example described, four pairs of opposite nozzles 7 of the two sets E1, E2 are balanced and do not influence the axial trajectory of the missile.

When it is desired to modify the trajectory of the missile for any reason, an order is given to act, via the control electronics 32, on the shutter 16 of the nozzle pair of the selected device 8 or, of course, on the electronic control of several shutters of the chosen pairs if one wants for example to print to the missile movements according to the axes of roll, pitch and yaw (referential Oxyz) around the center of gravity, and / or forces in a plane yz perpendicular to the x axis, passing through the center of gravity G.

In the example reported to Figures 3, 4 and 5 or 6 , the shutter device 8 is powered by a suitable source not shown supplying the control electronics. The driving member 20 then excited causes, via the connecting mechanism 23 ( figures 2 and 5 ) or 30 ( figure 6 ), the angular pivoting of the shaft 19 in the selected direction and angle. In this way, the shutter 16 in the form of angular sector rotates about the axis A2 leaving the neutral position. A new position then taken by the shutter is illustrated by way of example in dashed line on the figure 4 , and it is then seen that the opening 17 towards the left nozzle in this figure is more closed with respect to the initial position where this opening is half open and half closed. On the other hand, simultaneously and vice versa, the opening 17 giving towards the right nozzle is more open.

It is thus clear that, in this new dashed line position, the passage section of the jet gas J exiting through the right nozzle is greater than the passage section of the gas jet exiting through the nozzle on the left.

If it is considered that the pair of nozzles of the device in question 8 belongs to the assembly E2 intended for the control of the attitude of the missile, and corresponds to that P1 located in the upper part of the figure 3 , it results from the rotation of the shutter (about 20 °), an action of gaseous jets J in both directions along the common axis A1 to the two nozzles, which causes a rolling motion of the missile around the axis A and control the degree of freedom in both directions by a single pair of nozzles. If we only act on this degree of freedom (roll axis), so as not to disturb the other degrees of freedom (pitch and yaw axes), it is preferable to act in the same way on the pair P3 of nozzles in the lower part of the figure 3 by the rotation of the shutter of the corresponding device. In this way, we obtain a symmetry of action of the two pairs P1, P3 of nozzles 7 and thus a pure pair to roll.

In the case where the pair P1 of the nozzles belongs to the assembly E1 intended for driving in force, by the implementation of the device 8 having caused the rotation of the shutter to the left, a force is generated to the right, according to the y axis, translating the missile on that side.

If we go back to the pairs of nozzles of the set E2, we can as well act in the same way on the shutters as differently.

For example, always considering the two pairs P1, P3 of opposite nozzles 7 in the upper and lower parts of the figure 3 we control two degrees of freedom with them, namely roll and yaw. If the shutters of the two devices 8 are turned in the same direction with identical rotation, a force is generated to the left or to the right perpendicular to the plane xz formed by the axes of roll x and yaw z, whereas, if they are rotated in opposite directions, a couple of rolls are generated around the axis A (x axis of the reference frame).

It is also possible to combine the action of the two pairs of nozzles above by, for example, turning the shutter 16 of the pair P1 by 20 ° to the left to create roll and the shutter 16 by 10 ° to the right. the pair P3 to create lace. Obviously this is done within the limits of missile control.

Such an operation is also achieved by the two pairs P2, P4 of nozzles 7, situated in the left and right parts of the figure 3 , where one can control two degrees of freedom, namely rolling and pitching. If the shutters 16 of the two pairs P2, P4 are rotated in the same direction with identical rotation, a force is generated upwards or downwards perpendicularly to the xy plane formed by the roll axes x and pitch y, while that, if they are rotated in opposite directions, a couple of rolls are generated around the axis A (x axis).

Any combination of the four pairs of nozzles in the direction of rotation of the shutters and the given angle is of course possible to modulate the passage sections of the gaseous jet in the nozzles and then obtain the desired trajectory and achievable by the missile. This is valid for both the E1 set and the E2 set.

Such an arrangement in four pairs of two sets implies some redundancy between the pairs of nozzles in the movements along the axes. Although this is not binding, it could be envisaged, without departing from the scope of the invention, an arrangement with three pairs of nozzles regularly distributed at 120 ° from each other around the axis A of the body.

The control system 6 according to the invention makes it possible to guide the missile along its trajectory to the target by acting on the three degrees of freedom of the missile by an attitude control around the xyz axes of the reference frame and / or by exerting efforts on it passing through its center of gravity.

Claims (6)

1. System for guiding a flying machine having a longitudinal axis (A) up to a target throughout its trajectory, such as a missile or the like, using lateral gaseous jets, comprising a gas generator (5) capable of being connected to lateral nozzles (7) by means of movable obturating devices (8), which control the flow of the gases from the generator through said nozzles, said nozzles being associated in pairs (P1, P2, P3, P4) such that the nozzles of each pair are aligned along the same axis (A1) and arranged in opposition to each other, there being, between the two aligned nozzles of the pair, a single controllable obturating device (8) which is connected to said generator (5) and capable of controlling the flow of the gases through said nozzles (7) in the two senses, the pairs (P1, P2, P3, P4) of nozzles (7) being contained in a plane that is perpendicular to the machine axis (A), each obturating device (8) being able to alter the cross sections of flow for the gases from the generator through the nozzles, doing so in the reverse manner from one another, each obturating device being of the type having a rotating obturator (16), characterised in that said plane containing the pairs of nozzles passes through the center of gravity (G) of the machine and in that each obturating device (8) additionally comprises a controllable driver (20) which receives the proportional operating commands and is joined to the obturator (16) so as to move the same and to continuously alter the cross section of flow for the gases flowing through the nozzles (7).
2. System according to claim 1, characterised in that four pairs (P1, P2, P3, P4) of nozzles (7) are arranged so as to be uniformly distributed relative to one another, the four pairs being diametrically opposed two by two.
3. System according to either claim 1 or claim 2, characterised in that two sets (E1, E2) of pairs (P1, P2, P3, P4) of aligned and opposed nozzles (7) are provided in planes (PL1, PL2) which are mutually parallel and are perpendicular to the longitudinal axis of the machine, one (PL1) of said planes passing through the centre of gravity (G) of said machine.
4. System according to any of claims 1 to 3, characterised in that the nozzle pairs, with each of which a single obturating device (8) is associated, are located at the periphery of the external cylindrical body (2) of the machine and surround the gas generator (5) while in fluid communication therewith.
5. System according to one of claims 1 to 4, characterised in that each obturating device (8) comprises a body (14) having an internal passage (15) in which the rotating obturator (16) is received and which has two diametrically opposed openings (17) which are each joined to one of the necks of the aligned and opposed nozzles (7), and an opening (18) which is joined to the gas generator (5).
6. System according to one of claims 1 to 5, characterised in that said driver (20) is a torque motor which is joined parallel to or coaxially with a rotating shaft (19) bearing said obturator by means of a connection mechanism (23, 30).

Images