Annular retention system for a nozzle needle

Abstract

Annular retention system for a nozzle needle The invention relates to a nozzle (100) comprising a needle (110) movable between a first position and a second position, a stop (113) integral with the needle (110) and an annular retention system (150) of the needle comprising at least a first ring (161), a second ring (162) movable relative to the first ring (161) and at least one seal (171), such that when the needle (110) is in the first position, the first ring (161) is in contact with the stop (113) and the second ring (162) is at a non-zero distance from the stop (113), and such that when the needle (110) is in the second position, the first and second rings (161, 162) are in contact with the stop (113). Figure for abstract: Fig. 2

Description

Title of the invention: Annular system for retaining a nozzle needle Technical field

[0001] The present invention relates to the general field of thruster nozzles or rocket engines intended to deliver thrust for piloting vehicles such as missiles, launchers or even satellites, using the principle of propulsion by gas ejection. Prior art

[0002] The use of a needle that is movable in translation relative to a nozzle neck is well known. The position of the movable needle in the flow of gases from the nozzle determines the passage section of the gases exiting the nozzle and thus determines the thrust level, according to the principle of jet propulsion. The needle is conventionally moved by means of an actuator. Such systems are described in particular in documents EP 1 101 030 B1 and WO 2017 / 013341.

[0003] Current actuators have a significant mass and bulk, and require a significant amount of energy to be able to operate. Indeed, the actuator must provide significant forces to move the needle, in particular to oppose the aerodynamic forces exerted by the ejection gases on the distal part of the needle. In addition, since the aerodynamic forces exerted are very variable, the actuator must be capable of providing forces over a significant amplitude. Statement of the invention

[0004] The aim of the invention is to reduce the mass and size of the actuator, by reducing the amplitude of the forces that it must deploy to move the needle.

[0005] To this end, the invention provides a nozzle comprising a needle intended to be movable along an axis of movement relative to a body comprising a nozzle neck and defining an ejection chamber intended to be traversed by combustion gases, the needle being movable at least between a first position corresponding to a first ejection section and a second position corresponding to a second ejection section smaller than the first ejection section, the nozzle further comprising a stop secured to the needle, the nozzle being characterized in that it comprises an annular needle retention system having a first side facing the stop and a second opposite side in communication with the ejection chamber and comprising at least a first ring having a first diameter, a second ring having a second diameter greater than the first diameter, each of the rings extending between the first side and the second side and the first ring being movable relative to the second ring along the axis of movement, and at least one seal providing a seal between the first and second sides, the nozzle being configured to take a first configuration in which the needle is in the first position, the first ring is in contact with the stop and the second ring is at a non-zero distance from the stop, and to take a second configuration in which the needle is in the second position and the first and second rings are in contact with the stop with a movement of the first ring by the stop relative to the second ring.

[0006] Thus, the annular needle retention system makes it possible to compensate for the aerodynamic force, in order to obtain a total force on the needle that is as constant as possible, and preferably as low as possible. The force applied by the annular retention system depends on the equivalent engaged surface of said annular retention system, that is to say the surface of the annular retention system bearing on the needle, onto which the pressure prevailing in the ejection chamber is transmitted.

[0007] When the ejection section is reduced, that is to say when the needle is very advanced at the nozzle neck, the aerodynamic force exerted on the needle tends to make it advance even more at the nozzle neck. In this configuration, the equivalent engaged surface of the annular needle retention system must be large, in order to retain the needle or facilitate its return to the ejection chamber. For this purpose, the needle retention system is configured so that the first ring and the second ring bear on the needle. Thus, the equivalent engaged surface of said annular retention system is large.

[0008] On the contrary, when the ejection section is large, that is to say when the needle is not very advanced at the nozzle neck, the aerodynamic force exerted on the needle tends to make it return towards the ejection chamber. In this configuration, the equivalent engaged surface of the annular needle retention system must be small, so as not to encourage the needle to return further into the ejection chamber or to facilitate its advance towards the nozzle neck. For this purpose, the needle retention system is configured so that only the first ring bears on the needle. Thus, the equivalent engaged surface of said annular retention system is small.

[0009] Therefore, the force required by the actuator to move the needle has a lower amplitude, or is even lower in absolute value. Thus, lighter and less bulky actuator models can be chosen. In addition, the mass and size of the on-board electronic system can also be reduced. The amplitude of the forces to be deployed in the entire transmission chain of the actuator is reduced, thus limiting the wear of the parts.

[0010] According to a particular aspect of the invention, the annular needle retention system is arranged around the needle and extends between the needle and the body.

[0011] Thus, the annular needle retention system can be easily integrated into existing nozzles.

[0012] According to a first variant of the invention, the annular needle retention system is arranged around a retention member secured to the needle, said retention member being movable along a retention axis different from the axis of movement of the needle.

[0013] According to a second variant of the invention, the annular needle retention system is arranged in a chamber inside the needle, said chamber being in communication with the ejection chamber.

[0014] According to a particular aspect of the invention, the stop comprises at least a first portion and a second portion set back from the first portion, the second portion having a diameter greater than the diameter of the first portion, the first ring being in contact with the first portion of the stop when the needle is in the first position and in the second position, the second ring being in contact with the second portion of the stop when the needle is in the second position.

[0015] Thus, the rings are moved by means of a step-shaped stop.

[0016] According to a particular aspect of the invention, the body comprises stop portions arranged circumferentially around the axis of movement of the needle and extending radially opposite the first side of the annular retention system, so that when a ring of the annular retention system of the needle is at a non-zero distance from the stop, said ring is in contact with the stop portions of the body, free spaces being defined between said stop portions capable of being crossed by the stop during movement of the needle.

[0017] Thus, the rings which must not come into contact with the needle are stopped by such stop portions. Therefore, under the effect of the pressure in the ejection chamber, the rings which must not come into contact are pushed against the stop portions of the body and not against the needle. This architecture makes it possible to stop the rings without modifying their geometry.

[0018] According to an alternative, the rings of the annular system comprise a shoulder at the second side of the annular needle retention system, so that when a ring of the annular needle retention system is at a non-zero distance from the stop, the shoulder of said ring is in contact with the adjacent ring of larger diameter or the body.

[0019] Thus, the rings which must not come into contact with the needle are stopped by their shoulder. Therefore, under the effect of the pressure in the ejection chamber, the rings which must not come into contact are stopped by the rings of larger diameter or by the body. This architecture makes it possible to simply stop the rings, without requiring complex machining on the proximal part of the needle or at the level of the orifice of the body allowing the passage of the needle.

[0020] According to a particular aspect of the invention, the sealing gasket covers the second side of the annular needle retention system and is arranged in contact with a circumferential edge of each of the rings.

[0021] Such an architecture is simple to implement and inexpensive. In addition, such an architecture allows for a greater number of rings for the same size, which allows for better discretization of the force applied by the needle retention system.

[0022] According to a particular aspect of the invention, the annular needle retention system has a bellows structure, each ring being connected to an adjacent ring by a seal capable of unfolding and folding.

[0023] Such seals are easy to implement. The bellows structure allows for optimal sealing and satisfactory operation even at very high temperatures. However, such an annular retention system can be more bulky and heavier, and may therefore be more suitable for terrestrial applications.

[0024] According to a particular aspect of the invention, the annular needle retention system comprises a first seal interposed between the first ring and the second ring and a second seal surrounding the second ring.

[0025] According to a particular aspect of the invention, the annular needle retention system comprises at least a first seal interposed between the first ring and the second ring and a second seal surrounding the second ring, in which the stop is a flat surface perpendicular to the axis of movement of the needle, the first ring having a first length along the axis of movement of the needle and the second ring having a second length along the axis of movement of the needle less than the first length, the rings of the annular system comprising a shoulder at the second side of the annular needle retention system, so that when a ring of the annular needle retention system is at a non-zero distance from the stop, the shoulder of said ring is in contact with the adjacent ring of greater diameter or the body.

[0026] Thus, simple annular seals can be used.

[0027] According to a particular aspect of the invention, the needle is movable between the second position and a third position corresponding to a third ejection section more smaller than the second ejection section, the nozzle further comprising a third ring having a third diameter greater than the second diameter, the third ring extending between the first side and the second side and the first and second rings being movable relative to the third ring along the axis of movement, the third ring being at a non-zero distance from the stop when the nozzle assumes the first configuration and when the nozzle assumes the second configuration, the nozzle being configured to assume a third configuration in which the needle is in the third position and the third ring is in contact with the stop with a displacement of the first and second rings by the stop relative to the third ring.

[0028] Thus, the compensation force generated by the needle retention system can be more precise.

[0029] According to a particular aspect of the invention, the sealing joints are made of elastomer material or silicone. Brief description of the drawings

[0030] [Fig-1] [Fig.l] is a sectional diagram of a nozzle according to a first mode of embodiment in which the needle is in a first position.

[0031] [Fig.2] [Fig.2] is a sectional diagram of the nozzle according to the first embodiment in which the needle is in a second position.

[0032] [Fig.3] [Fig.3] is a sectional diagram of the nozzle according to the first embodiment in which the needle is in a third position.

[0033] [Fig.4] [Fig.4] is an exploded perspective diagram of a part of the nozzle according to the first embodiment of the invention.

[0034] [Fig.5] [Fig.5] is a graph illustrating the forces exerted on the needle.

[0035] [Fig.6] [Fig.6] is a sectional diagram of a nozzle according to a second mode of embodiment in which the needle is in an initial position.

[0036] [Fig.7] [Fig.7] is a sectional diagram of the nozzle according to the second embodiment in which the needle is in a first position.

[0037] [Fig.8] [Fig.8] is a sectional diagram of the nozzle according to the second embodiment in which the needle is in a second position.

[0038] [Fig.9] [Fig.9] is a sectional diagram of a nozzle according to a third embodiment in which the needle is in a second position.

[0039] [Fig. 10] [Fig. 10] is a sectional diagram of a nozzle according to a fourth embodiment in which the needle is in a second position.

[0040] [Fig. 11] [Fig. 11] is a sectional diagram of a nozzle according to a fifth embodiment in which the needle is in a first position.

[0041] [Fig. 12] [Fig. 12] is a sectional diagram of the nozzle according to the fifth embodiment in which the needle is in an advanced position.

[0042] [Fig. 13] [Fig. 13] is a cross-sectional diagram of a nozzle according to a first variant.

[0043] [Fig. 14] [Fig. 14] is a cross-sectional diagram of a nozzle according to a second variant.

[0044] [Fig. 15] [Fig. 15] is a diagram of the passage surface according to the second variant. Description of the embodiments

[0045] The method of the invention can be applied to any type of nozzle, whether or not comprising a diverging portion.

[0046] Figures 1 to 4 illustrate an example of a gas ejection section nozzle 100 according to a first embodiment of the invention.

[0047] The nozzle 100 comprises a needle 110 and a body 120. The body 120 comprises a nozzle neck 121. The needle 110 is movable relative to the nozzle neck 121 along a displacement axis X. The needle 110 extends lengthwise along the displacement axis X and radially along the radial direction R. The body 120 comprises a passage surface 122 opposite the gas ejection section along the displacement axis X. The passage surface 122 comprises an orifice 123 extending along the displacement axis X. The orifice 123 allows the passage of the needle 110. The needle 110 passes through the orifice 123 of the passage surface 122. The body 120 further comprises a main surface 124 connecting the nozzle neck 121 to the passage surface 122. The main surface 124 of the body 120 extends in the direction of movement X around the needle 110.

[0048] An actuator 130 actuates the needle 110 in translation along the displacement axis X. The actuator 130 can be positioned on the side delimited by the passage surface 122 opposite the gas ejection section. The needle 110 is movable between several positions along the displacement axis X. In particular, the needle 110 is movable at least between a first position and a second position.

[0049] [Fig.l] illustrates the nozzle 100 when it is in a first configuration, in which the needle 110 is in a first position. The first position of the needle 110 corresponds to a first gas ejection section Sp

[0050] [Fig. 2] illustrates the nozzle 100 when it is in a second configuration, in which the needle 110 is in a second position. The second position of the needle 110 corresponds to a second gas ejection section S2 smaller than the first gas ejection section Si.

[0051] [Fig. 3] illustrates the nozzle 100 when it is in a third configuration, in which the needle 110 is in a third position. The third position of the needle 110 corresponds to a third gas ejection section S3 smaller than the first gas ejection section S1 and the second gas ejection section S2.

[0052] The needle 110 comprises a proximal portion 111 and a distal portion 112 opposite the proximal portion 111 along the displacement axis X. The proximal portion 111 may be directly adjacent to the distal portion 112 along the displacement axis X. The gas ejection section is defined between the distal portion 112 of the needle 110 and the nozzle neck 121. The distal portion 112 of the needle 110 thus forms a member for partially closing the nozzle neck 121. The proximal portion 111 of the needle 110 is connected to the actuator 130. The proximal portion 111 of the needle 110 passes through the passage surface 122. The proximal portion 111 of the needle 110 passes through the orifice 123 of the passage surface 122. The proximal portion 111 of the needle 110 passes through the orifice 123 of the passage surface 122. distal 112 of the needle 110 may have an axisymmetric shape.

[0053] The nozzle 100 further comprises an ejection chamber 140 defined between the needle 110 and the body 120. In particular, the chamber 140 is delimited by the passage surface 122 and the main surface 124 of the body 120. The chamber 140 has a pressure PChammer representative of the pressure of the gas(es) coming from the combustion chamber.

[0054] In this first embodiment of the invention, the retention system 150 is arranged around the needle 110. The retention system 150 extends circumferentially around the displacement axis X. The retention system 150 is present in the chamber 140. The retention system 150 comprises a first side 151 and a second side 152 opposite the first side 151 along the displacement axis X. The first side 151 of the retention system 150 is arranged opposite the passage surface 122 of the body 120. The second side 152 of the retention system 150 is arranged opposite the gas ejection section. The retention system 150 provides a seal between the first side 151 and the second side 152.

[0055] The retention system 150 extends radially between the needle 110 and the body 120. In particular, the retention system 150 extends radially between the needle 110 and the main surface 124 of the body 120. The retention system 150 is in contact with the external surface of the needle 110. The retention system 150 is in contact with the body 120. In particular, the retention system 150 is in contact with the main surface 124 and the passage surface 122 of the body 120.

[0056] The retention system 150 comprises a plurality of concentric rings 161, 162, 163, 164. The retention system 150 comprises a plurality of concentric annular seals 171, 172, 173 interposed between the rings 161, 162, 163, 164. A single annular seal 171, 172, 173 is interposed between each ring 161, 162, 163, 164. Thus, the retention system 150 presents radially an alternation between rings and seals.

[0057] Preferably, the annular seals 171, 172, 173 are each in contact with two rings 161, 162, 163, 164. Thus, a first ring 161 is in contact with the needle and a last ring 164 is in contact with the body 120. The retention system 150 therefore comprises a number n of seals and a number n+1 of rings. The seals 171, 172, 173 are therefore preferably not in contact with the body 120 or the needle 110. Thus, the retention system 150 is easier to mount on the nozzle 100 and the wear of the seals 171, 172, 173 is more limited.

[0058] In the example illustrated in Figures 1 to 4, the retention system 150 comprises four rings and three seals. It is of course not beyond the scope of the first embodiment of the invention if the retention system 150 comprises only two seals. It is also not beyond the scope of the first embodiment of the invention if the retention system 150 comprises more than three seals.

[0059] The first ring 161 is in contact with the needle 110 and has a first diameter. The second ring 162 is arranged around the first ring 161 and has a second diameter greater than the first diameter of the first ring 161. The third ring 163 is arranged around the second ring 162 and has a third diameter greater than the second diameter of the second ring 162. The fourth ring 164 is arranged around the third ring 163 and has a fourth diameter greater than the third diameter of the third ring 163. The fourth ring 164 is in contact with the main surface 124 of the body 120.

[0060] The rings 161, 162, 163, 164 each extend from the first side 151 to the second side 152 of the retention system 150.

[0061] The first seal 171 is interposed between the first ring 161 and the second ring 162. The first seal 171 is in contact with the first ring 161 and the second ring 162. The first seal 171 surrounds the first ring 161. The second seal 172 is interposed between the second ring 162 and the third ring 163. The second seal 172 is in contact with the second ring 162 and the third ring 163. The second seal 172 surrounds the second ring 162. The third seal 173 is interposed between the third ring 163 and the fourth ring 164. The third seal 173 is in contact with the third ring 163 and the fourth ring 164. The third seal 173 surrounds the third ring 163.

[0062] The thickness of the rings in the radial direction may be between 10% and 100% of the thickness of the seals in the radial direction.

[0063] In this first embodiment of the invention, the proximal part 111 of the needle 110 and the passage surface 122 of the body 120 have a geometry particular for interacting with the retention system 150, as illustrated in exploded view in [Fig.4].

[0064] The orifice 123 of the passage surface 122 has a central portion 123a and at least one secondary portion 123b extending radially from the central portion. The central portion 123a has a cylindrical shape of revolution around the displacement axis X. Preferably, the orifice 123 of the passage surface 122 comprises a plurality of secondary portions 123b extending radially from the central portion. The circumferential space between the one or more secondary portions 123b of the orifice 123 defines stop portions 122c of the passage surface 122 extending towards the displacement axis X.

[0065] The proximal portion 111 of the needle 110 comprises a stop 113 extending circumferentially around the displacement axis X in a discontinuous manner. Thus, the stop 113 comprises one or more portions 113b distributed circumferentially around the displacement axis X. Each portion 113b of the stop 113 corresponds to a secondary portion 123b of the orifice 123. The portion(s) 113b of the stop 113 and the secondary portion(s) 123b of the orifice 123 of the passage surface 122 are configured so that the portions 113b of the stop 113 can slide in the secondary portions 123b of the orifice 123.

[0066] The stop portions 122c are intended to retain the rings which must not come into contact with the stop 113 of the needle 110.

[0067] The stop 113 comprises a plurality of stop surfaces 1131, 1132, 1133. The stop surfaces 1131, 1132, 1133 are each circumferentially discontinuous. The stop surfaces 1131, 1132, 1133 each have a crown shape extending discontinuously around the displacement axis X. The stop surfaces 1131, 1132, 1133 are present on the portion(s) 113b of the stop 113. The number of stop surfaces 1131, 1132, 1133 corresponds to the number of joints of the retention system 150. The stop 113 has a stepped shape. Thus, each stop surface 1131, 1132, 1133 is located at a different axial position on the axis of the needle 110. The further the stop surface is from the distal part 112 of the needle 110, the larger its radius.

[0068] A first stop surface 1131 is located at a first axial position on the axis of the needle 110 and has a first radius. The first stop surface 1131 is intended to be in contact with the first ring 161 when the first ring 161 is in contact with the stop 113. A second stop surface 1132 is located at a second axial position on the axis of the needle 110, the second axial position being further from the distal portion 112 of the needle 110 than the first axial position. Thus, the second stop surface 1132 is set back relative to the first stop surface 1132. The second stop surface 1132 has a second radius greater than the first radius. The second abutment surface 1132 is intended to be in contact with the second ring 162 when the second ring 162 is in contact with the abutment 113. A third abutment surface 1133 is located at a third axial position on the axis of the needle 110, the third axial position being further from the distal portion 112 of the needle 110 than the second axial position. Thus, the third abutment surface 1133 is set back relative to the second abutment surface 1132. The third abutment surface 1133 has a third radius greater than the second radius. The third abutment surface 1133 is intended to be in contact with the third ring 163 when the third ring 163 is in contact with the abutment 113.

[0069] The proximal portion 111 of the needle 110 further comprises at least one groove 11e. The groove(s) 111c extend lengthwise along the movement axis X and extend circumferentially between the portions 113b of the stop 113. Each groove 11c of the distal portion 111 of the needle 110 corresponds to a projection 122c of the passage surface 122. The groove(s) 11c of the distal portion 111 and the stop portion(s) 122c of the passage surface 122 are configured so that the stop portions 122c of the passage surface 122 can slide in the grooves 111c of the distal portion 111. The stop surfaces 1131, 1132, 1133 are interrupted at the groove(s) 11c.

[0070] Thus, the distal part 111 of the needle 110 can slide in the orifice 123 of the passage surface 122. Sliding is facilitated in the case where the distal part 111 comprises several grooves 11c and where the passage surface 122 comprises several stop portions 122c.

[0071] When the needle 110 is in the first position as illustrated in [Fig. 1], the first ring 161 is in contact with the stop 113. The other rings 162, 163, 164 are in contact with the body 120. In particular, the first ring 161 is in contact with the first stop surface 1131. The other rings 162, 163, 164 are in contact with the passage surface 122. The other rings 162, 163, 164 are retained by the stop portions 122c of the passage surface 122. Thus, the other rings 162, 163, 164 are not in contact with the needle 110. Therefore, the retention system 150 makes it possible to obtain a first equivalent engaged surface having as its radius the radius of the first seal 171.Thus, the force generated by the retention system 150 when the needle is in the first position is quite low, which makes it possible not to add, to the aerodynamic force exerted on the needle, too great a force in the direction opposite to the neck 121 so as not to hinder a subsequent movement of the needle towards the neck 121.

[0072] When the needle 110 is in the second position as illustrated in [Fig.2], the first ring 161 and the second ring 162 are in contact with the stop 113. The other rings 163, 164 are in contact with the body 120. In particular, the first ring 161 is in contact with the first stop surface 1131 and the second ring 162 is in contact with the second stop surface 1132. The other rings 163, 164 are in contact with the passage surface 122. The other rings 163, 164 are retained by the stop portions 122c of the passage surface 122. Thus, the other rings 163, 164 are not in contact with the needle 110. Therefore, the retention system 150 makes it possible to obtain a second equivalent surface engaged to compensate for the aerodynamic force, having as its radius the radius of the second seal 172. Consequently, the second equivalent surface engaged is larger than the first equivalent surface engaged. Thus, the force generated by the retention system 150 when the needle is in the second position is greater than the force generated by the retention system 150 when the needle is in the first position.In fact, the aerodynamic force in the second position pushes the needle more towards the nozzle neck than in the first position. Therefore, the force generated by the retention system must be greater in order to better retain the needle, and to facilitate a possible return to the first position.

[0073] When the needle 110 is in the third position as illustrated in [Fig. 3], the first ring 161, the second ring 162 and the third ring 163 are in contact with the stop 113. The last ring 164 is in contact with the body 120. In particular, the first ring 161 is in contact with the first stop surface 1131, the second ring 162 is in contact with the second stop surface 1132 and the third ring 163 is in contact with the third stop surface 1133. The last ring 164 is in contact with the passage surface 122. The last ring 164 is retained by the stop portions 122c of the passage surface 122. Therefore, the retention system 150 makes it possible to obtain a third equivalent surface engaged to compensate for the aerodynamic force, having as its radius the radius of the third seal 173. Therefore, the third equivalent engaged surface is larger than the second equivalent engaged surface.Thus, the force generated by the retention system 150 when the needle is in the third position is greater than the force generated by the retention system 150 when the needle is in the first position or in the second position. Indeed, the aerodynamic force in the third position pushes the needle more to advance towards the nozzle neck than in the second position. Therefore, the force generated by the retention system must be greater in order to better retain the needle, and to facilitate a possible return to the second position.

[0074] The transition from the first configuration to the second configuration of the nozzle 100 is done by moving the needle 110, so that the first ring 161 is pushed by the stop 113 and the stop 113 comes into contact with the second ring 162. The transition from the second configuration to the third configuration of the nozzle 100 is done by moving the needle 110, so that the first ring 161 is pushed by the stop 113 and the stop 113 comes into contact with the second ring 162. done by moving the needle 110, so that the first ring 161 and the second ring 162 are pushed by the stop 113 and the stop 113 comes into contact with the third ring 163.

[0075] The transition from the third configuration to the second configuration of the nozzle 100 is done by moving the needle, the pressure PChamber of the chamber 140 making it possible to press the rings 161, 162, 163 against the stop 113, until the third ring 163 is stopped by the stop portions 122c of the passage surface 122. The transition from the second configuration to the first configuration of the nozzle 100 is done by moving the needle, the pressure PChamber of the chamber 140 making it possible to press the third ring 163 against the stop portions 112c and the first and second rings 161, 162 against the stop 113, until the second ring 162 is stopped by the stop portions 122c.

[0076] [Fig. 5] is a graph illustrating how the force generated by the retention system 150 Fi50 makes it possible to compensate for the aerodynamic force Faéro to obtain a low and almost constant total force Ftotai on the needle 110. The graph indicates the force in Newtons on the ordinate and the axial position of the needle along the axis of movement on the abscissa. The increasing direction of the abscissa corresponds to the direction of retraction of the needle 110, that is to say to the increase in the ejection section. The decreasing direction of the abscissa corresponds to the direction of advance of the needle 110 in the nozzle neck 121. On this graph, the increasing direction of the ordinate corresponds to a force directed in a direction opposite to the neck 121 or towards the ejection chamber.

[0077] The aerodynamic force Faéro decreases continuously when the needle moves between the first position and the third axial position. It can be seen in the example illustrated in [Fig.5] that when the ejection section is small (abscissa close to 0), the aerodynamic force exerted on the needle is negative, i.e. it tends to make it move further forward at the nozzle neck. When the ejection section is large (abscissa close to 6 mm), the aerodynamic force exerted on the needle is positive, i.e. it tends to make the needle return towards the ejection chamber.

[0078] The force generated by the Fi50 retention system increases in stages as the Faéro aerodynamic force decreases. Indeed, as soon as a new ring is pressed against the needle, the force generated by the Fi50 retention system increases by one stage. There are as many stages as the retention system has seals. The more seals the retention system has, the more it is possible to discretize the force generated by the Fi50 retention system. However, seals and rings that are too thin in the radial direction may be too fragile or may not transmit the forces correctly. Therefore, the number of seals chosen may be a compromise so as to obtain a satisfactory discretization of the generated force while maintaining rings and seals thick enough to be resistant and correctly transmit the forces. Thus, for certain applications, the number of seals can be between 3 and 5 for an optimal compromise.

[0079] Figures 6 to 8 illustrate an example of a nozzle 200 according to a second embodiment of the invention.

[0080] The nozzle 200 comprises a needle 210 and a body 220. The body 220 comprises a nozzle neck 221. The needle 210 is movable relative to the nozzle neck 221 along a displacement axis X. The needle 210 extends lengthwise along the displacement axis X and radially along the radial direction R. The body 220 comprises a passage surface 222 opposite the gas ejection section along the displacement axis X. The passage surface 222 comprises an orifice 223 extending along the displacement axis X. The orifice 223 has a cylindrical shape of revolution of axis X. The orifice 223 allows the passage of the needle 210. The needle 210 passes through the orifice 223 of the passage surface 222. The body 220 further comprises a main surface 224 connecting the nozzle neck 221 to the passage surface 222. The main surface 224 of the body 220 extends in the direction of movement X around the needle 210.

[0081] An actuator 230 actuates the needle 210 in translation along the displacement axis X. The actuator 230 can be positioned on the side delimited by the passage surface 222 opposite the gas ejection section. The needle 210 is movable between several positions along the displacement axis X. In particular, the needle 210 is movable at least between a first position and a second position.

[0082] [Fig. 6] illustrates the nozzle 200 when it is in an initial configuration, in which the needle 210 is in an initial position. The initial position of the needle 210 corresponds to an initial gas ejection section So.

[0083] [Fig.7] illustrates the nozzle 200 when it is in a first configuration, in which the needle 210 is in a first position. The first position of the needle 210 corresponds to a first gas ejection section Si smaller than the initial gas ejection section So.

[0084] [Fig. 8] illustrates the nozzle 200 when it is in a second configuration, in which the needle 210 is in a second position. The second position of the needle 210 corresponds to a second gas ejection section S2 smaller than the initial gas ejection section So and the first gas ejection section Si.

[0085] The needle 210 comprises a proximal portion 211 and a distal portion 212 opposite the proximal portion 211 along the axis of movement X. The proximal portion 211 may be directly adjacent to the distal portion 212 along the axis of displacement X. The gas ejection section is defined between the distal portion 212 of the needle 210 and the nozzle neck 221. The distal portion 212 of the needle 210 thus forms a member for partially closing the nozzle neck 221. The proximal portion 211 of the needle 210 is connected to the actuator 230. The proximal portion 211 of the needle 210 passes through the passage surface 222. The proximal portion 211 of the needle 210 passes through the orifice 223 of the passage surface 222. The distal portion 212 of the needle 110 may have an axisymmetric shape.

[0086] The nozzle 200 further comprises an ejection chamber 240 defined between the needle 210 and the body 220. In particular, the chamber 240 is delimited by the passage surface 222 and the main surface 224 of the body 220. The chamber 240 has a pressure PChammer representative of the pressure of the gas(es) coming from the combustion chamber.

[0087] In this second embodiment of the invention, the retention system 250 is arranged around the needle 210. The retention system 250 extends circumferentially around the displacement axis X. The retention system 250 passes through the orifice 223 of the passage surface 222. The retention system 250 comprises a first side 251 and a second side 252 opposite the first side 251 along the displacement axis X. The first side 251 of the retention system 250 is arranged on one side of the passage surface 222 of the body 220 and the second side 252 of the retention system 250 is arranged on the other side of the passage surface 222 of the body 220. The second side 252 of the retention system 250 is arranged opposite the gas ejection section. The retention system 250 provides a seal between the first side 251 and the second side 252. Thus, the retention system 250 provides a seal at the orifice 223 of the passage surface 222.

[0088] The retention system 250 extends radially between the needle 210 and the body 220. In particular, the retention system 250 extends radially between the needle 210 and the edge of the orifice 223 of the passage surface 222 of the body 220. The retention system 250 is in contact with the external surface of the needle 210. The retention system 250 is in contact with the body 220. In particular, the retention system 250 is in contact with the edge of the orifice 223 of the passage surface 222 of the body 220.

[0089] The retention system 250 comprises a plurality of concentric rings 261, 262 in contact with each other. The retention system 250 comprises a plurality of concentric annular seals 271, 272, 273. A single annular seal is interposed between each ring. The annular seals 271, 272, 271 do not extend from the first side 251 to the second side 252.

[0090] Preferably, in order to limit the number of rings required, an annular seal 271 is interposed between the needle 210 and the first ring 261 and an annular seal 273 is interposed between the passage surface 222 and the last ring 262. The retention system 250 therefore comprises a number n of seals and a number n-1 of rings.

[0091] In the example illustrated in Figures 6 to 8, the retention system 250 comprises two rings and three seals. It is of course not beyond the scope of the second embodiment of the invention if the retention system 250 comprises only two seals. It is also not beyond the scope of the first embodiment of the invention if the retention system 250 comprises more than three seals.

[0092] The first ring 261 is in contact with the needle 210 and has a first diameter. The second ring 262 is arranged around the first ring 261 and has a second diameter greater than the first diameter of the first ring 261. The external surface of the first ring 261 is in contact with the internal surface of the second ring 262. The rings 261, 262 each extend from the first side 251 to the second side 252 of the retention system 250.

[0093] The first seal 271 is interposed between the needle 210 and the first ring 261. The first seal 271 is in contact with the external surface of the needle 210 and in contact with the first ring 261. The second seal 272 is interposed between the first ring 261 and the second ring 262. The second seal 272 is in contact with the first ring 261 and the second ring 262. The second seal 272 surrounds the first ring 262. The third seal 273 is interposed between the second ring 262 and the edge of the orifice 223 of the passage surface 222. The third seal 273 is in contact with the second ring 262 and the edge of the orifice 223 of the passage surface 222. The third seal 273 surrounds the second ring 263.

[0094] In this second embodiment of the invention, the rings 261, 262 have different lengths along the displacement axis X. The closer a ring is to the needle 210, the greater its length along the displacement axis X will be. Thus, the first ring 261 has a first length along the displacement axis X that is greater than the second length presented by the second ring 262 along the displacement axis X.

[0095] Furthermore, in this second embodiment of the invention, the rings 261, 262 have a shoulder 261a, 262a at the second side 252. The shoulder 261a, 262a extends perpendicular to the axis of movement X. The shoulder 261a, 262a is configured to be in contact with the adjacent ring of greater diameter or in contact with the passage surface 222, for one or more positions of the needle.

[0096] The proximal portion 211 of the needle 210 comprises a stop 213 extending circumferentially around the axis of movement X. The stop 213 forms a shoulder of the proximal portion 211 of the needle 210. The stop 213 is a flat surface perpendicular to the axis of movement X.

[0097] When the needle 210 is in the initial position as illustrated in [Fig. 6], the rings 261, 262 are at a non-zero distance from the stop 213. The shoulders 261a, 262a of the rings 261, 262 are in contact with the adjacent ring of larger diameter or with the passage surface 222. Thus, all the rings 261, 262 are directly or indirectly in contact with the passage surface 222 of the body 220. Thus, no ring 261, 262 is in contact with the needle 210. Therefore, the retention system 250 makes it possible to obtain an initial equivalent engaged surface to compensate for the aerodynamic force, having as its radius the radius of the first seal 271.Thus, the force generated by the retention system 250 when the needle is in the initial position is quite low, which makes it possible not to add, to the aerodynamic force exerted on the needle, too great a force in the direction opposite to the neck 121 so as not to hinder a subsequent movement of the needle towards the neck 121.

[0098] When the needle 210 is in the first position as illustrated in [Fig.7], the first ring 261 is in contact with the stop 213. The other ring(s) 262 are at a non-zero distance from the stop 213. The shoulder 261a of the first ring 261 is no longer in contact with the adjacent ring of larger diameter or with the body 220. The shoulder 262a of the other ring(s) 262 which are not in contact with the stop 213 are in contact with the adjacent ring of larger diameter or with the passage surface 222. Thus, all the other rings 262 are directly or indirectly in contact with the passage surface 222 of the body 220. Thus, no other ring 262 than the first ring 261 is in contact with the needle 210. Therefore, the retention system 250 makes it possible to obtain a first equivalent surface, having as its radius the radius of the second joint 272.Therefore, the first engaged equivalent surface is larger than the initial engaged equivalent surface. Thus, the force generated by the retention system 250 when the needle is in the first position is greater than the force generated by the retention system 250 when the needle is in the initial position. Thus, the force generated by the retention system 250 when the needle is in the first position is greater than the force generated by the retention system 250 when the needle is in the initial position. Indeed, the aerodynamic force in the first position pushes the needle more to advance towards the nozzle neck than in the initial position. Therefore, the force generated by the retention system must be greater in order to better retain the needle, and to facilitate a possible return to the initial position.

[0099] When the needle 210 is in the second position as illustrated in [Fig.8], the first ring 261 and the second ring 262 are in contact with the stop 213. Any other ring(s) are at a non-zero distance from the stop 213. The shoulders 261a, 262a of the first ring 261 and of the second ring 262 are no longer in contact with the adjacent ring of greater diameter or with the body 220. Thus, the first ring 261 and the second ring 262 bear on the needle 210. Therefore, the retention system 250 makes it possible to obtain a second equivalent engaged surface to compensate for the aerodynamic force, having as its radius the radius of the third seal 273. Consequently, the second equivalent engaged surface is larger than the first equivalent engaged surface. Thus, the force generated by the retention system 250 when the needle is in the second position is greater than the force generated by the retention system 250 when the needle is in the initial position or in the first position. Thus, the force generated by the retention system 250 when the needle is in the second position is greater than the force generated by the retention system 250 when the needle is in the first position.In fact, the aerodynamic force in the second position pushes the needle more towards the nozzle neck than in the first position. Therefore, the force generated by the retention system must be greater in order to better retain the needle, and to facilitate a possible return to the first position.

[0100] The transition from the initial configuration to the first configuration of the nozzle 200 is done by moving the needle 210, so that the stop 213 comes into contact with the first ring 261. The transition from the first configuration to the second configuration of the nozzle 200 is done by moving the needle 210, so that the first ring 261 is pushed by the stop 213 and the stop 213 comes into contact with the second ring 262.

[0101] The transition from the second configuration to the first configuration of the nozzle 200 is done by moving the needle, the pressure P chamber of the chamber 240 making it possible to press the rings 261, 262 against the stop 213, until the shoulder 262a of the second ring 262 is stopped by the adjacent ring of larger diameter or the passage surface 222. The transition from the first configuration to the initial configuration of the nozzle 200 is done by moving the needle, the pressure P chamber of the chamber 240 making it possible to press the second ring 262 against the adjacent ring of larger diameter or the passage surface 222 and making it possible to press the first ring 261 against the stop 213, until the shoulder 261a of the first ring 261 is stopped by the shoulder 262a of the second ring 262.

[0102] [Fig.9] illustrates an example of a gas ejection section nozzle 300 according to a third embodiment of the invention.

[0103] The nozzle 300 comprises a needle 310 and a body 320. The body 320 comprises a nozzle neck 321. The needle 310 is movable relative to the nozzle neck 321 along a displacement axis X. The needle 310 extends lengthwise along the displacement axis X and radially along the radial direction R. The body 320 may be merged or at least partially merged with the body of the nozzle. The body 320 may be distinct from the body of the nozzle. The body 320 comprises a passage surface 322 opposite the gas ejection section along the displacement axis X. The passage surface 322 comprises an orifice 323 extending along the displacement axis X. The orifice 323 has a cylindrical shape of revolution of axis X. The orifice 323 allows the passage of the needle 310. The needle 310 passes through the orifice 323 of the passage surface 322. The body 320 further comprises a main surface 324 connecting the nozzle neck 321 to the passage surface 322. The main surface 324 of the body 320 extends along the displacement direction X around the needle 310.

[0104] An actuator 330 actuates the needle 310 in translation along the displacement axis X. The actuator 330 can be positioned on the side delimited by the passage surface 322 opposite the gas ejection section. The needle 310 is movable between several positions along the displacement axis X. In particular, the needle 310 is movable at least between a first position and a second position.

[0105] When the nozzle 300 is in a first configuration (not shown), the needle 310 is in a first position. The first position of the needle 310 corresponds to a first gas ejection section Sp

[0106] [Fig. 9] illustrates the nozzle 300 when it is in a second configuration, in which the needle 310 is in a second position. The second position of the needle 310 corresponds to a second gas ejection section S2 smaller than the first gas ejection section Sp

[0107] When the nozzle 300 is in a third configuration, the needle 310 is in a third position. The third position of the needle 310 corresponds to a third gas ejection section S3 smaller than the first gas ejection section Si and the second gas ejection section S2.

[0108] The needle 310 comprises a proximal portion 311 and a distal portion 312 opposite the proximal portion 311 along the displacement axis X. The proximal portion 311 may be directly adjacent to the distal portion 312 along the displacement axis X. The gas ejection section is defined between the distal portion 312 of the needle 310 and the nozzle neck 321. The distal portion 312 of the needle 310 thus forms a member for partially closing the nozzle neck 321. The proximal portion 311 of the needle 310 is connected to the actuator 330. The proximal portion 311 of the needle 310 passes through the passage surface 322. The proximal portion 311 of the needle 310 passes through the orifice 323 of the passage surface 322. The proximal portion 311 of the needle 310 passes through the orifice 323 of the passage surface 322. distal 312 of the needle 310 may have an axisymmetric shape.

[0109] The nozzle 300 further comprises an ejection chamber 340 defined between the needle 310 and the body 320. In particular, the chamber 340 is delimited by the passage surface 322 and the main surface 324 of the body 320. The chamber 340 has a PChamber pressure representative of the pressure of the gas(es) coming from the combustion chamber.

[0110] The proximal portion 311 of the needle 310 comprises a stop 313 extending circumferentially around the displacement axis X. The stop 313 comprises a plurality of stop surfaces 3131, 3132, 3133. The stop surfaces 3131, 3132, 3133 each have a crown shape extending continuously around the displacement axis X. The number of stop surfaces 3131, 3132, 3133 may correspond to the number of rings of the retention system 350. The stop 313 has a stepped shape. Thus, each stop surface 3131, 3132, 3133 is located at a different axial position on the axis of the needle 310. The further the stop surface is from the distal portion 312 of the needle 310, the larger its radius.

[0111] A first stop surface 3131 is located at a first axial position on the axis of the needle 310 and has a first radius. The first stop surface is intended to be in contact with the first ring 361 when the first ring 361 is in contact with the stop 313. A second stop surface 3132 is located at a second axial position on the axis of the needle 310, the second axial position being further from the distal portion 312 of the needle 310 than the first axial position. Thus, the second stop surface 3132 is set back relative to the first stop surface 3131. The second stop surface 3132 has a second radius greater than the first radius. The second stop surface 3132 is intended to be in contact with the second ring 362 when the second ring 362 is in contact with the stop 313.A third abutment surface 3133 is located at a third axial position on the axis of the needle 310, the third axial position being further from the distal portion 312 of the needle 310 than the second axial position. Thus, the third abutment surface 3133 is recessed relative to the second abutment surface 3132. The third abutment surface 3133 has a third radius greater than the second radius. The third abutment surface 3133 is intended to be in contact with the third ring 363 when the third ring 363 is in contact with the abutment 313.

[0112] In this first embodiment of the invention, the retention system 350 is arranged around the needle 310. The retention system 350 extends circumferentially around the displacement axis X. The retention system 350 is present in the chamber 340. The retention system 350 comprises a first side 351 and a second side 352 opposite the first side 351 along the displacement axis X. The first side 351 of the retention system 350 is arranged opposite the passage surface 322 of the body 320. The second side 352 of the retention system 350 is arranged opposite the gas ejection section. The retention system 350 provides a seal between the first side 351 and the second side 352.

[0113] The retention system 350 extends radially between the needle 310 and the body 320. In particular, the retention system 350 extends radially between the needle 310 and the main surface 324 of the body 320. The retention system 350 is in contact with the external surface of the needle 310. The retention system 350 is in contact with the body 320. In particular, the retention system 350 is in contact with the main surface 324 and the passage surface 322 of the body 320.

[0114] The retention system 350 comprises a plurality of concentric rings 361, 362, 363, 364. The retention system 350 comprises a plurality of concentric annular seals 371, 372, 373 interposed between the rings 361, 362, 363, 364. A single annular seal 371, 372, 373 is interposed between each ring 361, 362, 363, 364. Thus, the retention system 350 has a radial alternation between rings and seals.

[0115] Preferably, the annular seals 371, 372, 373 are each in contact with two rings 361, 362, 363, 364. Thus, a first ring 361 is in contact with the needle 310 and a last ring 364 is in contact with the body 320. The retention system 350 therefore comprises a number n of seals and a number n+1 of rings. The seals 371, 372, 373 are therefore preferably not in contact with the body 320 or the needle 310. Thus, the retention system 350 is easier to mount on the nozzle 300 and the wear of the seals 371, 372, 373 is more limited.

[0116] In the example illustrated in [Fig.9], the retention system 350 comprises four rings and three seals. It is of course not beyond the scope of the third embodiment of the invention if the retention system 350 comprises only two seals. It is also not beyond the scope of the third embodiment of the invention if the retention system 350 comprises more than three seals.

[0117] The first ring 361 is in contact with the needle 310 and has a first diameter. The second ring 362 is arranged around the first ring 361 and has a second diameter greater than the first diameter of the first ring 361. The third ring 363 is arranged around the second ring 362 and has a third diameter greater than the second diameter of the second ring 362. The fourth ring 364 is arranged around the third ring 363 and has a fourth diameter greater than the third diameter of the third ring 362. The fourth ring 364 is in contact with the main surface 324 of the body 320.

[0118] The rings 361, 362, 363, 364 each extend from the first side 351 to the second side 352 of the retention system 350.

[0119] The first seal 371 is interposed between the first ring 361 and the second ring 362. The first seal 371 is in contact with the first ring 361 and the second ring 362. The first seal 171 surrounds the first ring 361. The second seal 372 is interposed between the second ring 362 and the third ring 363. The second seal 372 is in contact with the second ring 362 and the third ring 363. The second seal 372 surrounds the second ring 362. The third seal 373 is interposed between the third ring 363 and the fourth ring 364. The third seal 373 is in contact with the third ring 363 and the fourth ring 364. The third seal 373 surrounds the third ring 363.

[0120] The thickness of the rings in the radial direction (excluding the shoulder) may be between 10% and 100% of the thickness of the seals in the radial direction.

[0121] In this third embodiment of the invention, at least a portion of the rings 361, 362, 363 have a shoulder 361a, 362a, 363a at the second side 352. The shoulder 361a, 362a, 363a extends perpendicular to the axis of movement X. The shoulder 361a, 362a, 363a is configured to be in contact with the adjacent ring of greater diameter or in contact with the passage surface 322, for one or more positions of the needle. In this third embodiment, at least the rings 362, 363 surrounding a seal and being surrounded by a seal of the retention system 350 have such a shoulder 362a, 363a. Optionally, the larger diameter ring 364 of the retention system 350 may also comprise such a shoulder, configured to be in contact with the body 320. Optionally, the first ring 361 in contact with the needle 310 may have such a shoulder 361a, as in the example illustrated in [Fig.9].

[0122] The presence of such a shoulder 361a on the first ring 361 can make it possible to place the nozzle 300 in an initial position, when the needle 310 is in an initial position. The initial position of the needle 310 corresponds to an initial gas ejection section So, which is larger than the first gas ejection section Si. When the needle 310 is in the initial position (not shown), all the rings 361, 362, 363 are at a non-zero distance from the stop 313 if the first ring 361 comprises a shoulder 361a as described previously. The shoulders 361a, 362a, 363a of the rings 361, 362, 363 are in contact with the adjacent ring of larger diameter or with the body 320. Thus, all the rings 361, 362, 363 are directly or indirectly in contact with the body 220. Thus, no ring 361, 362, 363 is in contact with the needle 310.If the needle 310 comprises an “initial” annular seal at the outside of its proximal part 311, the retention system 350 makes it possible to obtain an initial equivalent engaged surface to compensate for the aerodynamic force, having the radius of the “initial” seal as its radius. Thus, the force generated by the retention system 350 when the needle is in the initial position is very low.

[0123] When the needle 310 is in the first position (not shown), the first ring 361 is in contact with the stop 313. In particular, the first ring 361 is in contact with the first stop surface 3131. The other ring(s) 362, 363 are at a non-zero distance from the stop 313. The possible shoulder 361a of the first ring 361 is no longer in contact with the adjacent ring of greater diameter or with the body 320. The shoulders 362a, 363a of the other rings 362, 363 are in contact with the adjacent ring of greater diameter or with the body 320. Thus, all the other rings 362, 363, 364 are directly or indirectly in contact with the body 320. Thus, no ring other than the first ring 361 is in contact with the needle 310. Therefore, the retention system 350 makes it possible to obtain a first equivalent surface, having as its radius the radius of the first seal 371. Thus, the force generated by the retention system 350 when the needle is in the first position is quite low, which makes it possible not to add, to the aerodynamic force exerted on the needle, too great a force in the direction opposite to the neck 121 so as not to hinder a subsequent movement of the needle towards the neck 121.

[0124] When the needle 310 is in the second position as illustrated in [Fig. 9], the first ring 361 and the second ring 362 are in contact with the stop 313. In particular, the first ring 361 is in contact with the first stop surface 3131 and the second ring is in contact with the second stop surface 3132. The possible other ring(s) 363, 364 are at a non-zero distance from the stop 313. The shoulders 361a, 362a of the first ring 361 and of the second ring 362 are no longer in contact with the adjacent ring of greater diameter or of the body 320. Thus, the first ring 361 and the second ring 362 are in contact with the needle 310. Therefore, the retention system 350 makes it possible to obtain a second equivalent surface engaged to compensate for the force aerodynamic, having as radius the radius of the second joint 372. Consequently, the second equivalent engaged surface is larger than the first equivalent engaged surface.Thus, the force generated by the retention system 350 when the needle is in the second position is greater than the force generated by the retention system 350 when the needle is in the first position. Thus, the force generated by the retention system 350 when the needle is in the second position is greater than the force generated by the retention system 350 when the needle is in the first position. Indeed, the aerodynamic force in the second position pushes the needle more to advance towards the nozzle neck than in the first position. Therefore, the force generated by the retention system must be greater in order to better retain the needle, and to facilitate a possible return to the first position.

[0125] When the needle 310 is in the third position (not shown), the first ring 361, the second ring 362 and the third ring 363 are in contact with the stop 313. In particular, the first ring 361 is in contact with the first stop surface 3131, the second ring 362 is in contact with the second stop surface 3132 and the third ring 363 is in contact with the third stop surface 3133. The possible other ring(s) 364 are at a non-zero distance from the stop 313. The shoulders 361a, 362a, 363a of the first ring 361, of the second ring 362 and of the third ring 363 are no longer in contact with the adjacent ring of greater diameter or with the body 320. Thus, the first ring 361, the second ring 362 and the third ring 363 are in contact with the needle 310. Therefore, the retention system 350 makes it possible to obtain a third equivalent engaged surface to compensate for the aerodynamic force, having as its radius the radius of the third seal 373. Consequently, the third equivalent engaged surface is larger than the second equivalent engaged surface. Thus, the force generated by the retention system 350 when the needle is in the third position is greater than the force generated by the retention system 350 when the needle is in the first or second position.Thus, the force generated by the retention system 350 when the needle is in the third position is greater than the force generated by the retention system 350 when the needle is in the second position. Indeed, the aerodynamic force in the third position pushes the needle more towards the nozzle neck than in the second position. Therefore, the force generated by the retention system must be greater in order to better retain the needle, and to facilitate a possible return to the second position.

[0126] The transition from the initial configuration to the first configuration of the nozzle 300 is done by moving the needle 310, so that the stop 313 comes into contact with the first ring 361. The transition from the first configuration to the second configuration of the nozzle 300 is done by moving the needle 310, so that the first ring 361 is pushed by the stop 313 and the stop 313 comes into contact with the second ring 362. The transition from the second configuration to the third configuration of the nozzle 300 is done by moving the needle 310, so that the first ring 361 and the second ring 362 are pushed by the stop 313 and the stop 313 comes into contact with the third ring 363.

[0127] The transition from the third configuration to the second configuration of the nozzle 300 is done by moving the needle, the pressure P chamber of the chamber 340 making it possible to press the rings 361, 362 and 363 against the stop 313, until the shoulder 363a of the third ring 363 is stopped by the adjacent ring of greater diameter or by the body 320. The transition from the second configuration to the first configuration of the nozzle 300 is done by moving the needle, the pressure P chamber of the chamber 340 making it possible to press the third ring 363 against the adjacent ring of greater diameter or against the body 320 and making it possible to press the rings 361, 362 against the stop 313, until the shoulder 362a of the second ring 362 is stopped by the adjacent ring of greater diameter or by the body 329. The transition from the first configuration to the initial configuration of the nozzle 300 is made by moving the needle, the pressure PChammer of the chamber 340 allowing the second ring 362 to be pressed against the adjacent ring of greater diameter or the body 320 and allowing the first ring 361 to be pressed against the stop 313, until the shoulder 361a of the first ring 361 is stopped by the shoulder 362a of the second ring 362.

[0128] [Fig. 10] illustrates an example of a gas ejection section nozzle 400 according to a fourth embodiment of the invention.

[0129] The nozzle 400 comprises a needle 410 and a body 420. The body 420 comprises a nozzle neck 421. The needle 410 is movable relative to the nozzle neck 421 along a displacement axis X. The needle 410 extends lengthwise along the displacement axis X and radially along the radial direction R. The body 420 comprises a passage surface 422 opposite the gas ejection section along the displacement axis X. The passage surface 422 comprises an orifice 423 extending along the displacement axis X. The orifice 423 allows the passage of the needle 410. The needle 410 passes through the orifice 423 of the passage surface 422. The body 420 further comprises a main surface 424 connecting the nozzle neck 421 to the passage surface 422. The main surface 424 of the body 420 extends in the direction of movement X around the needle 410.

[0130] An actuator 430 actuates the needle 410 in translation along the displacement axis X. The actuator 430 can be positioned on the side delimited by the passage surface 422 opposite the gas ejection section. The needle 410 is movable between several positions along the displacement axis X. In particular, the needle 410 is movable at least between a first position and a second position.

[0131] When the nozzle 400 is in a first configuration, the needle 410 is in a first position. The first position of the needle 410 corresponds to a first gas ejection section Si.

[0132] [Fig. 10] illustrates the nozzle 400 when it is in a second configuration, in which the needle 410 is in a second position. The second position of the needle 410 corresponds to a second gas ejection section S2 smaller than the first gas ejection section Si.

[0133] When the nozzle 400 is in a third configuration, the needle 410 is in a third position. The third position of the needle 410 corresponds to a third gas ejection section S3 smaller than the first gas ejection section S1 and the second gas ejection section S2. The aerodynamic force is average in this configuration.

[0134] The needle 410 comprises a proximal part 411 and a distal part 412 opposite the proximal part 411 along the axis of movement X. The proximal part 411 may be directly adjacent to the distal portion 412 along the displacement axis X. The gas ejection section is defined between the distal portion 412 of the needle 410 and the nozzle neck 421. The distal portion 412 of the needle 410 thus forms a member for partially closing the nozzle neck 421. The proximal portion 411 of the needle 410 is connected to the actuator 430. The proximal portion 411 of the needle 410 passes through the passage surface 422. The proximal portion 411 of the needle 410 passes through the orifice 423 of the passage surface 422. The distal portion 412 of the needle 410 may have an axisymmetric shape.

[0135] The nozzle 400 further comprises an ejection chamber 440 defined between the needle 410 and the body 420. In particular, the chamber 440 is delimited by the passage surface 422 and the main surface 424 of the body 420. The chamber 440 has a pressure PChammer representative of the pressure of the gas(es) coming from the combustion chamber.

[0136] In this fourth embodiment of the invention, the retention system 450 is arranged around the needle 410. The retention system 450 extends circumferentially around the displacement axis X. The retention system 450 may be present in the chamber 440. The retention system 450 comprises a first side 451 and a second side 452 opposite the first side 451 along the displacement axis X. The first side 451 of the retention system 450 may be arranged opposite the passage surface 422 of the body 420. The second side 452 of the retention system 450 is arranged opposite the gas ejection section. The retention system 450 provides a seal between the first side 451 and the second side 452.

[0137] The retention system 450 extends radially between the needle 410 and the body 420. The retention system 450 is in contact with the external surface of the needle 410. The retention system 450 is in contact with the body 420.

[0138] The retention system 450 comprises a plurality of rings 461, 462, 463, 464 arranged around the movement axis X. The rings 461, 462, 463, 464 have different diameters. The rings 461, 462, 463, 464 are connected to each other by membranes 471, 472, 473 capable of folding and unfolding. Thus, the membranes 471, 472, 473 have a bellows shape. The membranes 471, 472, 473 may be flexible or rigid. The membranes fulfill a seal function. A single membrane 471, 472, 473 connects each ring 461, 462, 463, 464. The retention system 450 generally has a sealed bellows structure.The retention system 450 is thus able to fold into a configuration where the rings 461, 462, 463, 464 are concentric and where the membranes 471, 472, 472 are folded, and to unfold into a configuration where all the rings 461, 462, 463, 464 are axially offset from each other and where the membranes 471, 472, 473 are unfolded.

[0139] A first ring 461 is in contact with the needle 410. The first ring 461 can be attached to the needle 410. A last ring 464 is attached to the body 420. The retention system 450 therefore comprises a number n of membranes and a number n + 1 of rings. The membranes 471, 472, 473 are therefore preferably not in contact with the body 420 or the needle 410.

[0140] In the example illustrated in [Fig. 10], the retention system 450 comprises four rings and three membranes. It is of course not beyond the scope of the fourth embodiment of the invention if the retention system 450 comprises only two seals. It is also not beyond the scope of the fourth embodiment of the invention if the retention system 450 comprises more than three seals.

[0141] The first ring 461 has a first diameter. The second ring 462 has a second diameter greater than the first diameter of the first ring 461. The third ring has a third diameter greater than the second diameter of the second ring 462. The fourth ring 464 has a fourth diameter greater than the third diameter of the third ring 463. The fourth ring 164 is in contact with the body 420.

[0142] The first membrane 471 connects the first ring 461 to the second ring 462. The second membrane 472 connects the second ring 462 to the third ring 463. The third membrane 473 connects the third ring 463 to the fourth ring 464.

[0143] In this fourth embodiment of the invention, the proximal part 411 of the needle 410 and the passage surface 422 of the body 420 have a particular geometry for interacting with the retention system 450, corresponding to that illustrated in [Fig.4] in the context of the first embodiment of the invention.

[0144] The orifice 423 of the passage surface 422 has a central portion and at least one secondary portion extending radially from the central portion. The central portion has a cylindrical shape of revolution around the displacement axis X. Preferably, the orifice 423 of the passage surface 422 comprises a plurality of secondary portions extending radially from the central portion. The circumferential space between the one or more secondary portions of the orifice 423 defines stop portions of the passage surface 422 extending towards the displacement axis X.

[0145] The proximal portion 411 of the needle 410 comprises a stop 413 extending circumferentially around the displacement axis X in a discontinuous manner. Thus, the stop 413 comprises one or more portions distributed circumferentially around the displacement axis X. Each portion of the stop 413 corresponds to a secondary portion of the orifice 423. The portion(s) of the stop 413 and the secondary portion(s) of the orifice 423 of the passage surface 422 are configured so that the portions of the stop 413 can slide in the secondary portions of the orifice 423.

[0146] The stop portions are intended to retain the rings which must not come into contact with the stop 413 of the needle 410.

[0147] The stop 413 comprises a plurality of stop surfaces 4131, 4132, 4133. The stop surfaces 4131, 4132, 4133 are each circumferentially discontinuous. The stop surfaces 4131, 4132, 4133 each have a crown shape extending discontinuously around the displacement axis X. The stop surfaces 4131, 4132, 4133 are present on the portion(s) 413b of the stop 413. The number of stop surfaces 4131, 4132, 4133 may correspond to the number of membranes of the retention system 450. The stop 413 has a stepped shape. Thus, each stop surface 4131, 4132, 4133 is located at a different axial position on the axis of the needle 410. The further the stop surface is from the distal portion 412 of the needle 410, the larger its radius.

[0148] A first stop surface 4131 is located at a first axial position on the axis of the needle 410 and has a first radius. The first stop surface 4131 is intended to be in contact with the first ring 461 when the first ring 461 is in contact with the stop 413. A second stop surface 4132 is located at a second axial position on the axis of the needle 410, the second axial position being further from the distal portion 412 of the needle 410 than the first axial position. Thus, the second stop surface 4132 is set back relative to the first stop surface 4132. The second stop surface 4132 has a second radius greater than the first radius. The second abutment surface 4132 is intended to be in contact with the second ring 462 when the second ring 462 is in contact with the abutment 413.A third abutment surface 4133 is located at a third axial position on the axis of the needle 410, the third axial position being further from the distal portion 412 of the needle 410 than the second axial position. Thus, the third abutment surface 4133 is recessed relative to the second abutment surface 4132. The third abutment surface 4133 has a third radius greater than the second radius. The third abutment surface 4133 is intended to be in contact with the third ring 463 when the third ring 463 is in contact with the abutment 413.

[0149] The proximal portion 411 of the needle 410 further comprises at least one groove. The groove(s) extend lengthwise along the displacement axis X and extend circumferentially between the portions of the stop 413. Each groove of the distal portion 411 of the needle 410 corresponds to a projection of the passage surface 422. The groove(s) of the distal portion and the stop portion(s) of the passage surface 422 are configured so that the stop portions of the passage surface 422 can slide in the grooves of the distal portion 411. The stop surfaces 4131, 4132, 4133 are interrupted at the groove(s).

[0150] Thus, the distal portion 411 of the needle 410 can slide in the orifice 423 of the passage surface 422. Sliding is facilitated in the case where the distal portion 411 comprises several grooves and where the passage surface 422 comprises several stop portions.

[0151] When the needle 410 is in the first position (not shown), the first ring 461 is in contact with the stop 413. The other rings 462, 463, 464 are in contact with the body 420. In particular, the first ring 461 is in contact with the first stop surface 4131. The other rings 462, 463, 464 are in contact with the passage surface 422. The other rings 462, 463, 464 are retained by the stop portions of the passage surface 422. Thus, the other rings 462, 463, 464 are not in contact with the needle 410. Therefore, the retention system 450 makes it possible to obtain a first equivalent surface, having as its radius the radius of the first membrane 471.Thus, the force generated by the retention system 450 when the needle is in the first position is quite low, which makes it possible not to add, to the aerodynamic force exerted on the needle, too great a force in the direction opposite to the neck 121 so as not to hinder a subsequent movement of the needle towards the neck 121.

[0152] When the needle 410 is in the second position as illustrated in [Fig. 10], the first ring 461 and the second ring 462 are in contact with the stop 413. The other rings 463, 464 are in contact with the body 420. In particular, the first ring 461 is in contact with the first stop surface 4131 and the second ring 462 is in contact with the second stop surface 4132. The other rings 463, 464 are in contact with the passage surface 422. The other rings 463, 464 are retained by the stop portions of the passage surface 422. Thus, the other rings 463, 464 are not in contact with the needle 410. Therefore, the retention system 450 makes it possible to obtain a second equivalent surface engaged to compensate for the force aerodynamic, having as radius the radius of the second membrane 472. Consequently, the second equivalent engaged surface is larger than the first equivalent engaged surface.Thus, the force generated by the retention system 450 when the needle is in the second position is greater than the force generated by the retention system 450 when the needle is in the first position. Thus, the force generated by the retention system 450 when the needle is in the second position is greater than the force generated by the retention system 450 when the needle is in the first position. Indeed, the aerodynamic force in the second position pushes the needle more to advance towards the nozzle neck than in the first position. Therefore, the force generated by the retention system must be greater in order to better retain the needle, and to facilitate a possible return to the first position.

[0153] When the needle 410 is in the third position (not shown), the first ring 461, the second ring 462 and the third ring 463 are in contact with the stop 413. The last ring 464 is in contact with the body 420. In particular, the first ring 461 is in contact with the first stop surface 4131, the second ring 462 is in contact with the second stop surface 4132 and the third ring 463 is in contact with the third stop surface 4133. The last ring 464 is in contact with the passage surface 422. The last ring 464 is retained by the stop portions of the passage surface 422. Therefore, the retention system 450 makes it possible to obtain a third equivalent surface engaged to compensate for the aerodynamic force, having as its radius the radius of the third membrane 473. Consequently, the third surface equivalent engaged area is larger than the second equivalent engaged area.Thus, the force generated by the retention system 450 when the needle is in the third position is greater than the force generated by the retention system 450 when the needle is in the first position or in the second position. Thus, the force generated by the retention system 450 when the needle is in the third position is greater than the force generated by the retention system 450 when the needle is in the second position. Indeed, the aerodynamic force in the third position pushes the needle more to advance towards the nozzle neck than in the second position. Therefore, the force generated by the retention system must be greater in order to better retain the needle, and to facilitate a possible return to the second position.

[0154] The transition from the first configuration to the second configuration of the nozzle 400 is done by moving the needle 410, so that the first ring 461 is pushed by the stop 413 and the stop 413 comes into contact with the second ring 462. The transition from the second configuration to the third configuration of the nozzle 400 is done by moving the needle 410, so that the first ring 461 and the second ring 462 are pushed by the stop 413 and the stop 413 comes into contact with the third ring 463.

[0155] The transition from the third configuration to the second configuration of the nozzle 100 is done by moving the needle, the pressure P chamber of the chamber 440 making it possible to press the rings 461, 462, 463 against the stop 413, until the third ring 463 is stopped by the stop portions of the passage surface 422. The transition from the second configuration to the first configuration of the nozzle 400 is done by moving the needle, the pressure P chamber of the chamber 440 making it possible to press the third ring 463 against the stop portions and the first and second rings 461, 462 against the stop 413, until the second ring 462 is stopped by the stop portions.

[0156] Figures 11 and 12 illustrate an example of a gas ejection section nozzle 500 according to a fifth embodiment of the invention.

[0157] The nozzle 500 comprises a needle 510 and a body 520. The body 520 comprises a nozzle neck 521. The needle 510 is movable relative to the nozzle neck 521 along a displacement axis X. The needle 510 extends lengthwise along the displacement axis X and radially along the radial direction R. The body 520 comprises a passage surface 522 opposite the gas ejection section along the displacement axis X. The passage surface 522 comprises an orifice 523 extending along the displacement axis X. The orifice 523 allows the passage of the needle 510. The needle 510 passes through the orifice 523 of the passage surface 522. The body 520 further comprises a main surface 524 connecting the nozzle neck 521 to the passage surface 522. The main surface 524 of the body 520 extends in the direction of movement X around the needle 510.

[0158] An actuator 530 actuates the needle 510 in translation along the displacement axis X. The actuator 530 can be positioned on the side delimited by the passage surface 522 opposite the gas ejection section. The needle 510 is movable between several positions along the displacement axis X. In particular, the needle 510 is movable at least between a first position and a second position.

[0159] [Fig. 11] illustrates the nozzle 500 when it is in a first configuration, in which the needle 510 is in a first position. The first position of the needle 510 corresponds to a first gas ejection section Sp

[0160] When the nozzle 500 is in a second configuration (not shown), the needle 510 is in a second position. The second position of the needle 510 corresponds to a second gas ejection section S2 smaller than the first gas ejection section Sp

[0161] [Fig. 12] illustrates the nozzle 500 when it is in a third configuration, in which the needle 510 is in a third position. The third position of the needle 510 corresponds to a third gas ejection section S3 smaller than the first gas ejection section S1 and the second gas ejection section S2. The aerodynamic force is average in this configuration.

[0162] The needle 510 comprises a proximal portion 511 and a distal portion 512 opposite the proximal portion 511 along the displacement axis X. The proximal portion 511 may be directly adjacent to the distal portion 512 along the displacement axis X. The gas ejection section is defined between the distal portion 512 of the needle 510 and the nozzle neck 521. The distal portion 512 of the needle 510 thus forms a member for partially closing the nozzle neck 521. The proximal portion 511 of the needle 510 is connected to the actuator 530. The proximal portion 511 of the needle 510 passes through the passage surface 522. The proximal portion 511 of the needle 510 passes through the orifice 523 of the passage surface 522. The distal portion 512 of the needle 510 may have an axisymmetric shape.

[0163] The nozzle 500 further comprises an ejection chamber 540 defined between the needle 510 and the body 520. In particular, the chamber 540 is delimited by the passage surface 522 and the main surface 524 of the body 320. The chamber 540 has a pressure PChammer representative of the pressure of the gas(es) coming from the combustion chamber.

[0164] In this fifth embodiment of the invention, the retention system 550 is arranged around the needle 510. The retention system 550 extends circumferentially around the displacement axis X. The retention system 550 is present in the chamber 540. The retention system 550 comprises a first side 551 and a second side 552 opposite the first side 551 along the displacement axis X. The first side 551 of the retention system 550 is arranged opposite the passage surface 522 of the body 520. The second side 552 of the retention system 550 is arranged opposite the gas ejection section. The retention system 550 provides a seal between the first side 551 and the second side 552.

[0165] The retention system 550 extends radially between the needle 510 and the body 520. In particular, the retention system 550 extends radially between the needle 510 and the main surface 524 of the body 520. The retention system 550 is in contact with the external surface of the needle 510. The retention system 550 is in contact with the body 520. In particular, the retention system 550 is in contact with the main surface 524 and the passage surface 522 of the body 520.

[0166] The retention system 550 comprises a plurality of concentric rings 561, 562, 563, 564. The rings 561, 562, 563, 564 are in contact with each other. The rings 561, 562, 563, 564 slide over each other. The other rings 562, 563 have their inner face in contact with the outer face of the adjacent ring of smaller diameter and their outer face in contact with the inner face of the adjacent ring of larger diameter. Thus, preferably, no element is interposed between the rings 561, 562, 563, 564.

[0167] The retention system 550 comprises a single seal 570. The seal 570 covers the second side 552 of the retention system 550. The seal 570 is in contact with the end of the rings 561, 562, 563, 564 at the second side 552 of the retention system 550. Thus, the seal 570 extends radially from the needle 510 towards the body 520. The seal 570 has a crown shape centered around the displacement axis X.

[0168] In the example illustrated in Figures 11 and 12, the retention system 550 comprises four rings. This does not, of course, depart from the scope of the fifth mode of embodiment of the invention if the retention system 550 comprises only two or three rings. It is also within the scope of the fifth embodiment of the invention if the retention system 550 comprises more than four rings.

[0169] The first ring 561 is in contact with the needle 510 and has a first diameter. The second ring 562 is arranged around the first ring 561 and has a second diameter greater than the first diameter of the first ring 561. The third ring 563 is arranged around the second ring 562 and has a third diameter greater than the second diameter of the second ring 562. The fourth ring 564 is arranged around the third ring 563 and has a fourth diameter greater than the third diameter of the third ring 563. The fourth ring 564 is in contact with the main surface 524 of the body 520.

[0170] In this fifth embodiment of the invention, the proximal part 511 of the needle 510 and the passage surface 522 of the body 520 may have a particular geometry to interact with the retention system 550, corresponding to that illustrated in [Fig.4] in the context of the first embodiment of the invention.

[0171] The orifice 523 of the passage surface 522 has a central portion and at least one secondary portion extending radially from the central portion. The central portion has a cylindrical shape of revolution around the displacement axis X. Preferably, the orifice 523 of the passage surface 522 comprises a plurality of secondary portions extending radially from the central portion. The circumferential space between the one or more secondary portions of the orifice 523 defines stop portions of the passage surface 522 extending towards the displacement axis X.

[0172] The proximal portion 511 of the needle 510 comprises a stop 513 extending circumferentially around the displacement axis X in a discontinuous manner. Thus, the stop 513 comprises one or more portions distributed circumferentially around the displacement axis X. Each portion of the stop 513 corresponds to a secondary portion of the orifice 523. The portion(s) of the stop 513 and the secondary portion(s) of the orifice 523 of the passage surface 522 are configured so that the portions of the stop 513 can slide in the secondary portions of the orifice 523.

[0173] The stop portions are intended to retain the rings which must not come into contact with the stop 513 of the needle 510.

[0174] The stop 513 comprises a plurality of stop surfaces 5131, 5132, 5133. The stop surfaces 5131, 5132, 5133 are each circumferentially discontinuous. The stop surfaces 5131, 5132, 5133 each have a crown shape extending discontinuously around the movement axis X. The stop surfaces 5131, 5132, 5133 are present on the portion(s) of the stop 513. The stop 513 has a stepped shape. Thus, each stop surface 5131, 5132, 5133 is located at a different axial position on the axis of the needle 510. The further the stop surface 5131, 5132, 5133 is from the distal portion 512 of the needle 510, the greater its radius.

[0175] A first stop surface 5131 is located at a first axial position on the axis of the needle 510 and has a first radius. The first stop surface is intended to be in contact with the first ring 561 when the first ring 561 is in contact with the stop 513. A second stop surface 5132 is located at a second axial position on the axis of the needle 510, the second axial position being further from the distal portion 512 of the needle 510 than the first axial position. Thus, the second stop surface 5132 is set back relative to the first stop surface 5131. The second stop surface 5132 has a second radius greater than the first radius. The second stop surface 5132 is intended to be in contact with the second ring 562 when the second ring 562 is in contact with the stop 513.A third abutment surface 5133 is located at a third axial position on the axis of the needle 510, the third axial position being further from the distal portion 512 of the needle 510 than the second axial position. Thus, the third abutment surface 5133 is recessed relative to the second abutment surface 5132. The third abutment surface 5133 has a third radius greater than the second radius. The third abutment surface 5133 is intended to be in contact with the third ring 563 when the third ring 563 is in contact with the abutment 513.

[0176] The proximal portion 511 of the needle 510 further comprises at least one groove. The groove(s) extend lengthwise along the displacement axis X and extend circumferentially between the portions of the stop 513. Each groove of the distal portion 511 of the needle 510 corresponds to a projection of the passage surface 522. The groove(s) of the distal portion 511 and the stop portion(s) of the passage surface 522 are configured such that the stop portions of the passage surface 522 can slide in the grooves of the distal portion 511. The stop surfaces are interrupted at the groove(s).

[0177] Thus, the distal portion 511 of the needle 510 can slide in the orifice 523 of the passage surface 522. Sliding is facilitated in the case where the distal portion 511 comprises several grooves and where the passage surface 522 comprises several stop portions.

[0178] When the needle 510 is in the first position as illustrated in [Fig. 11], the first ring 561 is in contact with the stop 513. The other rings 562, 563, 564 are in contact with the body 520. In particular, the first ring 561 is in contact with the first stop surface. The first stop surface is aligned with the passage surface 522. The other rings 562, 563, 564 are in contact with the passage surface 522. All rings 561, 562, 563, 564 are aligned at the same axial position. Thus, the seal 570 is straight with respect to the movement axis X. The seal 570 therefore has a minimal surface area in the first configuration. Therefore, the retention system 550 makes it possible to obtain a first equivalent surface, corresponding to the surface of the seal 570. Thus, the force generated by the retention system 550 when the needle is in the first position is quite low, which makes it possible not to add, to the aerodynamic force exerted on the needle, too great a force in the direction opposite to the neck 121 so as not to hinder a subsequent movement of the needle towards the neck 121. In particular, the diameter of the first ring 561 can be determined so that the force generated by the retention system 550 compensates for the aerodynamic force when the needle 510 is in the first position.

[0179] When the needle 510 is in the second position, the first ring 561 and the second ring 562 are in contact with the stop 513. The other rings 563, 564 are in contact with the body 520. In particular, the first ring 561 is in contact with the first stop surface and the second ring 562 is in contact with the second stop surface. The second stop surface is aligned with the passage surface 522. The other rings 563, 564 are in contact with the passage surface 522. Thus, the first ring 561 is in an axial position different from the axial position of the other rings 562, 563, 564. Thus, the first ring 561 deforms the seal 570. The seal 570 therefore has a larger surface in the second configuration than in the first configuration. Therefore, the retention system 550 makes it possible to obtain a second equivalent surface engaged to compensate for the aerodynamic force, corresponding to the surface of the seal 570.The second equivalent engaged surface is greater than the first equivalent engaged surface. Thus, the force generated by the retention system 550 when the needle is in the second position is greater than the force generated by the retention system 550 when the needle is in the first position. Thus, the force generated by the retention system 550 when the needle is in the second position is greater than the force generated by the retention system 550 when the needle is in the first position. Indeed, the aerodynamic force in the second position pushes the needle more to advance towards the nozzle neck than in the first position. Therefore, the force generated by the retention system must be greater in order to better retain the needle, and to facilitate a possible return to the first position.

[0180] When the needle 510 is in the third position as illustrated in [Fig. 12], the first ring 561, the second ring 562 and the third ring 563 are in contact with the stop 513. The other ring(s) 564 are in contact with the body 520. In particular, the first ring 561 is in contact with the first stop surface, the second ring 562 is in contact with the second stop surface and the third ring 563 is in contact with the third stop surface. The third stop surface is aligned with the passage surface 522. The other ring(s) 564 are in contact with the passage surface 522. Thus, the first ring 561 is at a first axial position. The second ring 562 is at a second axial position different from the first axial position. The other rings 563, 564 are at a third axial position different from the first and second axial positions. The second axial position is an intermediate position between the first axial position and the third axial position. Thus, the first ring 561 and the second ring 562 deform the seal 570. The seal 570 therefore has a larger surface area in the third configuration than in the first and second configurations.Therefore, the retention system 550 makes it possible to obtain a third equivalent engaged surface to compensate for the aerodynamic force, corresponding to the surface of the seal 570. The third equivalent engaged surface is greater than the first and second equivalent engaged surfaces. Thus, the force generated by the retention system 550 when the needle is in the third position is greater than the force generated by the retention system 550 when the needle is in the first position and in the second position. Thus, the force generated by the retention system 550 when the needle is in the third position is greater than the force generated by the retention system 550 when the needle is in the second position. Indeed, the aerodynamic force in the third position pushes the needle more to advance towards the nozzle neck than in the second position.Therefore, the force generated by the retention system must be greater in order to better retain the needle, and to facilitate a possible return to the second position.

[0181] The transition from the first configuration to the second configuration of the nozzle 500 is done by moving the needle 510, so that the first ring 561 is pushed by the stop 513 and the stop 513 comes into contact with the second ring 562. The transition from the second configuration to the third configuration of the nozzle 500 is done by moving the needle 510, so that the first ring 561 and the second ring 562 are pushed by the stop 113 and the stop 513 comes into contact with the third ring 163.

[0182] The transition from the third configuration to the second configuration of the nozzle 500 is done by moving the needle, the pressure P chamber of the chamber 540 making it possible to press the rings 561, 562, 563 against the stop 513, until the second ring 562 is aligned with the rings of larger diameter 563, 564. The transition from the second configuration to the first configuration of the nozzle 500 is done by moving the needle, the pressure P chamber of the chamber 540 making it possible to press the first ring 561 against the stop 513, until the first ring 561 is axially aligned with the other rings 562, 563, 564.

[0183] In all of the embodiments described above, the needle retention system is arranged around the needle.

[0184] According to a first variant of each of the embodiments described above, the retention system can be arranged around a retention axis different from the axis of movement of the needle. The retention axis is preferably parallel to the axis of movement of the needle.

[0185] [Fig. 13] illustrates an example of a nozzle 600 according to the first variant, applied to the first embodiment of the invention. It is of course not outside the scope of the invention if the first variant is applied to the second, third, fourth or fifth embodiment of the invention.

[0186] The retention system 650 is then arranged around a retention member 660, said retention member 660 being integral with the needle 610. Thus, the rings exerting a force on the retention member 660 also exert a force on the needle 610. The retention member 660 is subjected to the pressure PChammer of the chamber 640 representative of the pressure of the gas(es) coming from the combustion chamber. Thus, the retention member 660 is subjected to the same pressure as the proximal part 611 of the needle 610. The stop 613 as described in the previous embodiments of the invention is present on the retention member 660 in this first variant. The passage surface 622 then comprises an additional orifice 625 extending along the retention axis XR. The additional orifice 625 allows the passage of the retention member 660. The retention member 660 passes through the additional orifice 625 of the passage surface 662.The additional orifice 625 may have the architecture as described for the orifice in previous embodiments of the invention.

[0187] According to a second variant of each of the embodiments described above, the retention system can be arranged inside the needle. The retention system is arranged around the axis of movement of the needle.

[0188] [Fig. 14] illustrates an example of a nozzle 700 according to the first variant, applied to the first embodiment of the invention. It is of course not outside the scope of the invention if the first variant is applied to the second, third, fourth or fifth embodiment of the invention.

[0189] The retention system 750 is arranged in an internal chamber 770 inside the needle 710. The internal chamber 770 is subjected to a pressure representative of the pressure of the gas(es) coming from the combustion chamber. Thus, the retention system 750 is subjected to the same pressure as the proximal portion 711 of the needle 710.

[0190] The retention system 750 is arranged around a retention member 760, said retention member 760 being integral with the needle 710 and arranged inside the needle 710. Thus, the rings exerting a force on the retention member 760 also exert a force on the needle 710. The stop 713 as described in the previous embodiments of the invention is present on the retention member 760 in this second variant.

[0191] As illustrated in [Fig. 15], the orifice 723 of the passage surface 722 has a crown shape centered around the axis of movement of the needle X. The orifice 723 allows at least the external surface of the needle 710 to slide. The passage surface 722 further comprises an additional orifice 725 extending along the axis of movement X of the needle 710. The orifice 723 and the additional orifice 725 of the passage surface 722 are concentric. The additional orifice 725 allows the passage of the retention member 760. The retention member 760 passes through the additional orifice 725 of the passage surface 722. The additional orifice 725 may have the architecture as described for the orifice in the previous embodiments of the invention.

[0192] Thus, the rings come to bear on the stop 713 of the retention member 760 or on the portion 722a of the passage surface 722 of the body 720 extending between the orifice 723 and the additional orifice 725.

[0193] In all the embodiments of the invention described above, the rings may be made of metallic material. In all the embodiments of the invention described above, the rings may be made of composite material.

[0194] In all the embodiments of the invention described above, the seals can be made of elastomer. In all the embodiments of the invention described above, the seals can be made of silicone. The seals are made of a deformable material.

[0195] The needle retention system in the various embodiments of the invention can compensate for the maximum aerodynamic force experienced by the distal part of the needle by at least 60%.

[0196] In all the embodiments described above and as explained in detail in the first embodiment of the invention, the aerodynamic force decreases continuously when the needle moves between the first position and the third axial position. The force generated by the retention system increases in stages as the aerodynamic force decreases. Indeed, as soon as a new ring is pressed against the needle or the retention member, the force generated by the retention system increases by one stage. There are as many stages as the retention system has seals or membranes. The more seals or membranes the retention system has, the more it is possible to discretize the force generated by the retention system. However, seals and rings that are too thin in the radial direction may be too fragile or may not transmit the forces correctly. Therefore, the The number of seals or membranes chosen can be a compromise so as to obtain a satisfactory discretization of the force generated while maintaining rings and seals thick enough to be resistant and correctly transmit the forces. Thus, for certain applications, the number of seals or membranes can be between 3 and 5 for an optimal compromise.

[0197] By way of example, the dimensioning described below may be adopted in the first and third embodiments, including in the context of the first and second variants, in the case of a retention system with three elastomer seals having an elongation capacity of 400% and a shear modulus of 0.2 MPa. In this dimensioning, the internal radius of the first seal, the second seal and the third seal is 5.65 mm, 7.15 mm and 8.65 mm respectively. The stiffness of the first seal, the second seal and the third seal according to a strength of materials (RDM) approach is 89 N / mm, 112 N / mm and 136 N / mm respectively. The thickness of the seals along the radial direction DR is 1 mm. The length of the seals along the direction of movement X is 12.5 mm. The thickness of the rings in the radial direction DR is 0.5 mm.Such a dimensioning allows a needle travel of 6 mm, or 2 mm allowed per seal, under 10 MPa.

[0198] The nozzle obtained can be used for any type of system comprising needle valves. In particular, the nozzle obtained can be used in thrusters, missiles, rocket engines or launchers with solid, liquid or hybrid propulsion.

Claims

Claims

1. Nozzle (100) comprising a needle (110) intended to be movable along a displacement axis (X) relative to a body (120) comprising a nozzle neck (121) and defining an ejection chamber (140) intended to be traversed by combustion gases, the needle (110) being movable at least between a first position corresponding to a first ejection section and a second position corresponding to a second ejection section smaller than the first ejection section, the nozzle further comprising a stop (113) integral with the needle (110), the nozzle (100) being characterized in that it comprises an annular retention system (150) for the needle having a first side (151) facing the stop (113) and a second side (152) opposite in communication with the ejection chamber (140) and comprising at least at least a first ring (161) having a first diameter,a second ring (162) having a second diameter greater than the first diameter, each of the rings (161, 162, 163, 164) extending between the first side (151) and the second side (152) and the first ring (161) being movable relative to the second ring (162) along the axis of movement (X), and at least one seal (171) providing a seal between the first and second sides (151, 152), the nozzle (100) being configured to take a first configuration in which the needle (110) is in the first position, the first ring (161) is in contact with the stop (113) and the second ring (162) is at a non-zero distance from the stop (113), and to take a second configuration in which the needle (110) is in the second position and the first and second rings (161, 162) are in contact with the stop (113) with a displacement of the first ring (161) by the stop relative to the second ring (162).,

2. The nozzle (100) of claim 1, wherein the annular needle retention system (150) is disposed around the needle (110) and extends between the needle (110) and the body (120).

3. The nozzle (700) of claim 1, wherein the annular needle retention system (750) is disposed in a chamber (770) inside the needle (710), said chamber (770) being in communication with the ejection chamber.

4. Nozzle (600) according to claim 1, in which the annular needle retention system (650) is arranged around a retention member (660) integral with the needle (610), said retention member (660) being movable along a retention axis (XR) different from the displacement axis (X) of the needle (610).

5. Nozzle (100) according to any one of claims 1 to 4, wherein the stop (113) comprises at least a first portion (1131) and a second portion (1132) set back from the first portion (1131), the second portion (1132) having a diameter greater than the diameter of the first portion (1131), the first ring (161) being in contact with the first portion (1131) of the stop (113) when the needle (110) is in the first position and in the second position, the second ring (162) being in contact with the second portion (1132) of the stop (113) when the needle (110) is in the second position.

6. Nozzle (100) according to claim 5, wherein the body (120) comprises stop portions (122c) arranged circumferentially around the axis of movement (X) of the needle (110) and extending radially opposite the first side (151) of the annular retention system (150), so that when a ring (162, 163, 164) of the annular retention system of the needle (150) is at a non-zero distance from the stop (113), said ring (162, 163, 164) is in contact with the stop portions (122c) of the body (120), free spaces (123b) being defined between said stop portions (122c) capable of being crossed by the stop (113) during the movement of the needle (110).

7. A nozzle (300) according to claim 5, wherein the rings (362, 363) of the annular system (350) comprise a shoulder (362a, 363a) at the second side (352) of the annular needle retention system (350), such that when a ring (362, 363) of the annular needle retention system (350) is at a non-zero distance from the stop (313), the shoulder (362a, 363a) of said ring (362, 363) is in contact with the adjacent ring of larger diameter or the body (320).

8. A nozzle (500) according to claim 5 or 6, wherein the seal (570) covers the second side (572) of the annular needle retention system (550) and is disposed in contact of a circumferential edge of each of the rings (561, 562, 563, 564).

9. Nozzle (400) according to claim 5 or 6, in which the annular needle retention system (450) has a bellows structure, each ring (461, 462, 463, 464) being connected to an adjacent ring by a seal (471, 472, 473) capable of unfolding and folding.

10. Nozzle (100) according to one of claims 5 to 7, in which the annular needle retention system (150) comprises a first seal (171) interposed between the first ring (161) and the second ring (162) and a second seal (172) surrounding the second ring (162).

11. A nozzle (200) according to any one of claims 1 to 4, wherein the annular needle retention system (250) comprises at least a first seal (272) interposed between the first ring (261) and the second ring (262) and a second seal (273) surrounding the second ring (262), wherein the stop (213) is a flat surface perpendicular to the axis of movement (X) of the needle (210), the first ring (261) having a first length along the axis of movement (X) of the needle (210) and the second ring (262) having a second length along the axis of movement (X) of the needle (210) less than the first length, the rings (261, 262) of the annular system (250) comprising a shoulder (261a, 262a) at the second side (252) of the system needle retention ring (250), so that when a ring (261,262) of the annular needle retention system (250) is at a non-zero distance from the stop (213), the shoulder (261a, 262a) of said ring (261a, 262a) is in contact with the adjacent ring of greater diameter or the body (220).,

12. A nozzle (100) according to any one of claims 1 to 11, wherein the needle (110) is movable between the second position and a third position corresponding to a third ejection section smaller than the second ejection section, the nozzle further comprising a third ring (163) having a third diameter greater than the second diameter, the third ring (163) extending between the first side (151) and the second side (152) and the first and second rings (161, 162) being movable relative to the third ring (163) along the axis of

13. displacement (X), the third ring (163) being at a non-zero distance from the stop (113) when the nozzle (100) takes the first configuration and when the nozzle (100) takes the second configuration, the nozzle (100) being configured to take a third configuration in which the needle (110) is in the third position and the third ring (163) is in contact with the stop (113) with a displacement of the first and second rings (161, 162) by the stop (113) relative to the third ring (163). Nozzle (100) according to any one of claims 1 to 12, in which the sealing joints (171, 172, 173) are made of elastomeric material or silicone.

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