Annular system for retaining 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) for the needle comprising at least one first ring (161), a second ring (162) movable relative to the first ring (161), and at least one sealing gasket (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 the 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 rocket engine nozzles or rocket motors intended to deliver thrust for piloting vehicles such as missiles, launchers or satellites, using the principle of gas ejection propulsion. Previous technique

[0002] The use of a movable needle valve in translation relative to a nozzle throat is well known. The position of the movable needle valve in the nozzle gas flow determines the cross-sectional area of ​​the gases exiting the nozzle and thus determines the thrust level, according to the principle of reaction propulsion. The needle valve 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 significant mass and size, and require a substantial amount of energy to operate. Indeed, the actuator must exert considerable force to move the needle, particularly to counteract the aerodynamic forces exerted by the ejection gases on the distal part of the needle. Furthermore, since these aerodynamic forces are highly variable, the actuator must be capable of exerting force over a wide range. Description of the invention

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

[0005] To this end, the invention proposes a nozzle comprising a needle intended to be movable along an axis of displacement 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 integral with the needle, the nozzle being characterized in that it comprises an annular needle retention system having a first side opposite 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 displacement, and at least one sealing joint making 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 displacement of the first ring by the stop relative to the second ring.

[0006] Thus, the annular needle retention system compensates for the aerodynamic force, in order to obtain the most constant, and preferably the lowest, total force on the needle. The force applied by the annular retention system depends on the equivalent engaged surface area of ​​said annular retention system, that is, the surface area of ​​the annular retention system bearing against the needle, onto which the pressure prevailing in the ejection chamber is transmitted.

[0007] When the ejection area is reduced, that is, when the needle is very far forward at the nozzle throat, the aerodynamic force exerted on the needle tends to push it forward even further at the nozzle throat. In this configuration, the equivalent engaged surface area of ​​the annular needle retention system must be large in order to retain the needle or facilitate its return to the ejection chamber. To this end, the needle retention system is configured so that the first and second rings bear against the needle. Thus, the equivalent engaged surface area of ​​said annular retention system is large.

[0008] Conversely, when the ejection area is large, that is, when the needle is only slightly advanced at the nozzle throat, the aerodynamic force exerted on the needle tends to make it return towards the ejection chamber. In this configuration, the equivalent engaged surface area 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 throat. To this end, the needle retention system is configured so that only the first ring bears against the needle. Thus, the equivalent engaged surface area of ​​said annular retention system is small.

[0009] Consequently, the effort required from the actuator to move the needle is less pronounced, or even lower in absolute value. Therefore, lighter and more compact actuator designs can be selected. Furthermore, the mass and size of the embedded electronic system can also be reduced. The range of forces to be deployed throughout the actuator's transmission chain is reduced, thus limiting wear on 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 attached 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 disposed 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 stop in the form of a staircase.

[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 suitable for the stop to pass through during the movement of the needle.

[0017] Thus, the rings that should not bear against the needle are stopped by such stopping portions. Consequently, under the effect of the pressure in the ejection chamber, the rings that should not come to a stop are pushed against the stopping portions of the body and not against the needle. This design allows the rings to be stopped without altering their geometry.

[0018] According to an alternative, the rings of the annular system include a shoulder at the level of the second side of the annular system for retaining the needle, so that when a ring of the annular system for retaining the needle 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 that should not bear against the needle are stopped by their shoulder. Consequently, under the pressure in the ejection chamber, the rings that should not come to a stop are stopped by the larger diameter rings or by the body. This design allows the rings to be stopped simply, without requiring complex machining on the proximal part of the needle or at the opening in the body through which the needle passes.

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

[0021] Such an architecture is simple to implement and inexpensive. Furthermore, such an architecture allows for a greater number of rings within the same footprint, which enables 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 bulkier and heavier, and may therefore be better suited to land-based applications.

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

[0025] According to a particular aspect of the invention, the annular needle retention system comprises at least a first sealing gasket interposed between the first ring and the second ring and a second sealing gasket 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 level of 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 with the body.

[0026] Thus, simple annular joints 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 plus 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 displacement, the third ring being at a non-zero distance from the stop when the nozzle takes the first configuration and when the nozzle takes the second configuration, the nozzle being configured to take 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 effort generated by the needle retention system can be more precise.

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

[0030] [Fig-1] Fig. 1 is a cross-sectional diagram of a nozzle according to a first mode of construction in which the pointer is in a first position.

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

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

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

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

[0035] [Fig.6] Fig.6 is a cross-sectional diagram of a nozzle according to a second mode of an implementation in which the pointer is in an initial position.

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

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

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

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

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

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

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

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

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

[0045] The method of the invention can be applied to any type of nozzle, whether or not it includes a divergent part.

[0046] Figures 1 to 4 illustrate an example of a nozzle 100 with a gas ejection section 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 throat 121. The needle 110 is movable relative to the nozzle throat 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 throat 121 to the surface of passage 122. The main surface 124 of the body 120 extends along the direction of displacement X around the pointer 110.

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

[0049] Figure 1 illustrates the nozzle 100 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 ejection section of Sp gas

[0050] Figure 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 that is smaller than the first gas ejection section Si.

[0051] Figure 3 illustrates the nozzle 100 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, which is smaller than the first gas ejection section Si 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 axis of movement X. The proximal portion 111 may be directly adjacent to the distal portion 112 along the axis of movement 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 partial occlusion of 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 distal portion 112 of the pointer 110 may present 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 PChambre representative of the pressure of the gas(s) 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 axis of movement X. The retention system 150 is located 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 axis of movement X. The first side 151 of the retention system 150 is positioned opposite the passage surface 122 of the body 120. The second side 152 of the retention system 150 is positioned 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 150 retention system presents a radial 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 valve and a last ring 164 is in contact with the body 120. The retention system 150 therefore comprises n seals and n+1 rings. The seals 171, 172, 173 are therefore preferably not in contact with the body 120 or the needle valve 110. Thus, the retention system 150 is easier to mount on the nozzle 100 and wear on the seals 171, 172, 173 is reduced.

[0058] In the example illustrated in Figures 1 to 4, the retention system 150 comprises four rings and three seals. It is of course still within the scope of the first embodiment of the invention if the retention system 150 comprises only two seals. Nor is it within 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 larger 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 larger 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 larger 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 along the radial direction can be between 10% and 100% of the thickness of the seals along 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 on [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 about the axis of movement 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 secondary portion(s) 123b of the orifice 123 defines stop portions 122c of the passage surface 122 extending towards the axis of movement X.

[0065] The proximal portion 111 of the needle 110 includes a stop 113 extending circumferentially around the axis of movement X in a discontinuous manner. Thus, the stop 113 comprises one or more portions 113b distributed circumferentially around the axis of movement 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 such that the portions 113b of the stop 113 can slide within the secondary portions 123b of the orifice 123.

[0066] The stop portions 122c are intended to retain the rings which must not come to rest on 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 axis of displacement 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 in 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 pointer 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 pointer 110, the second axial position being further from the distal part 112 of the pointer 110 than the first axial position. Thus, the second stop surface 1132 is recessed relative to the first stop surface 1132. The second stop surface 1132 has a second radius The second stop surface 1132 is intended to be in contact with the second ring 162 when the second ring 162 is in contact with the stop 113. A third stop surface 1133 is located at a third axial position on the axis of the point 110, this third axial position being further from the distal part 112 of the point 110 than the second axial position. Thus, the third stop surface 1133 is set back relative to the second stop surface 1132. The third stop surface 1133 has a third radius that is larger than the second radius. The third stop surface 1133 is intended to be in contact with the third ring 163 when the third ring 163 is in contact with the stop 113.

[0069] The proximal part 111 of the needle 110 further includes at least one groove 11. The groove(s) 111c extend lengthwise along the axis of movement X and extend circumferentially between the portions 113b of the stop 113. Each groove 111 of the distal part 111 of the point 110 corresponds to an advance 122c of the passage surface 122. The groove(s) 111 of the distal part 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 part 111. The stop surfaces 1131, 1132, 1133 are interrupted at the groove(s) 111.

[0070] Thus, the distal part 111 of the needle 110 can slide in the orifice 123 of the passage surface 122. The sliding is facilitated in the case where the distal part 111 includes several grooves 11 the and where the passage surface 122 includes 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 bearing against the needle 110. Therefore, the retention system 150 makes it possible to obtain a first equivalent engaged surface having a radius equal to 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 collar 121 so as not to hinder a subsequent movement of the needle towards the collar 121. .

[0072] When the pointer 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 and 164 are in contact with the passage surface 122. The other rings 163 and 164 are retained by the stop portions 122c of the passage surface 122. Thus, the other rings 163 and 164 do not bear against the pin 110. Therefore, the retention system 150 provides a second equivalent engaged surface to compensate for the aerodynamic force, with a radius equal to the radius of the second seal 172. Consequently, the second equivalent engaged surface is larger than the first equivalent engaged surface. 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.Indeed, the aerodynamic force in the second position pushes the needle further forward towards the nozzle throat than in the first position. Therefore, the force generated by the retention system must be greater in order to better retain the needle and 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 engaged surface to compensate for the aerodynamic force, having a radius equal to the radius of the third seal 173. By Consequently, the third equivalent area involved is larger than the second equivalent area involved.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 or second position. Indeed, the aerodynamic force in the third position pushes the needle more towards the nozzle throat than in the second position. Therefore, the force generated by the retention system must be greater in order to better retain the needle and facilitate a possible return to the second position.

[0074] The transition from the first configuration to the second configuration of the nozzle 100 is achieved 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 pointer 110, so that the first ring 161 and the second ring 162 are pushed by the stop 113 and that 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 achieved by moving the needle, the chamber pressure PChambre of the chamber 140 allowing the rings 161, 162, 163 to be pressed 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 achieved by moving the needle, the chamber pressure PChambre of the chamber 140 allowing the third ring 163 to be pressed 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] Figure 5 illustrates how the force generated by the retention system 150 Fi50 compensates for the aerodynamic force Faéro to obtain a low and nearly constant total force Ftotai on the nozzle 110. The graph shows the force in newtons on the ordinate and the axial position of the nozzle along the axis of movement on the abscissa. The increasing direction of the abscissa corresponds to the direction of retraction of the nozzle 110, i.e., the increase in the ejection area. The decreasing direction of the abscissa corresponds to the direction of advance of the nozzle 110 in the nozzle throat 121. On this graph, the increasing direction of the ordinate corresponds to a force directed in the opposite direction to the throat 121 or towards the ejection chamber.

[0077] The aerodynamic force Faero decreases continuously as the needle moves between the first and third axial positions. In the example illustrated in [Fig. 5], it can be seen that when the ejection area is small (abscissa close to 0), the aerodynamic force exerted on the needle is negative, meaning it tends to move it further forward at the nozzle throat. When the ejection area is large (abscissa close to 6 mm), the aerodynamic force exerted on the needle is positive, meaning it tends to move the needle back towards the ejection chamber.

[0078] The force generated by the Fi50 retention system increases in steps as the aerodynamic force Faéro decreases. Indeed, as soon as a new ring is in contact with the needle, the force generated by the Fi50 retention system increases by one step. There are as many steps as there are seals in the retention system. 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 along the radial direction may be too fragile or not transmit the forces correctly. Therefore, the number of seals chosen may be a compromise in order to obtain A satisfactory discretization of the generated force is achieved while maintaining sufficiently thick rings and seals to be robust and transmit forces correctly. Therefore, for certain applications, the number of seals can range from 3 to 5 for an optimal compromise.

[0079] Figures 6 to 8 illustrate an example of 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 about 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 throat 221 to the passage surface 222. The main surface 224 of the body 220 extends along the direction of movement X around the needle 210.

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

[0082] Figure 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] Figure 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] Figure 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 that is 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 part 212 of the needle 210 and the nozzle neck 221. The distal part 212 of the needle 210 thus forms a partial occlusion of the nozzle neck 221. The proximal part 211 of the needle 210 is connected to the actuator 230. The proximal part 211 of the needle 210 passes through the passage surface 222. The proximal part 211 of the needle 210 passes through the orifice 223 of the passage surface 222. The distal part 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 PChambre representative of the pressure of the gas(s) 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 axis of movement 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 axis of movement X. The first side 251 of the retention system 250 is disposed on one side of the passage surface 222 of the body 220 and the second side 252 of the retention system 250 is disposed on the other side of the passage surface 222 of the body 220. The second side 252 of the retention system 250 is disposed 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. Only one annular seal is interposed between each ring. The annular seals 271, 272, 273 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 clearly still within the scope of the second embodiment of the invention if the retention system 250 comprises only two seals. Nor is it within 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 larger than the first diameter of the first ring 261. The outer surface of the first ring 261 is in contact with the inner surface of the second ring 262. The rings 261 and 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 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 flow surface 222. The third seal 273 is in contact with the second ring 262 and the edge of the orifice 223 of the flow surface 222. The third seal 273 surrounds the second ring 263.

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

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

[0096] The proximal part 211 of the pointer 210 includes a stop 213 extending circumferentially around the axis of displacement X. The stop 213 forms a shoulder of the proximal part 211 of the pointer 210. The stop 213 is a flat surface perpendicular to the axis of displacement 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 supported by the passage surface 222 of the body 220. Therefore, no ring 261, 262 is supported by the needle 210. Consequently, the retention system 250 provides an equivalent initial engaged surface to compensate for the aerodynamic force, having a radius equal to 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 collar 121 so as not to hinder a subsequent movement of the needle towards the collar 121. .

[0098] When the pointer 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 that 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 bearing on the passage surface 222 of the body 220. Therefore, no ring 262 other than the first ring 261 is bearing on the pointer 210. Consequently, the retention system 250 allows to obtain a first equivalent surface, having as its radius the radius of the second joint 272.Therefore, the first engaged equivalent area is larger than the initial engaged equivalent area. 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 forward more towards the nozzle throat than in the initial position. Consequently, the force generated by the retention system must be greater in order to better retain the needle and facilitate a possible return to the initial position.

[0099] When the pointer 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. The possible other ring(s) are at a non-zero distance from the stop 213. The shoulders 261a, 262a of the first ring 261 and the second ring 262 are no longer in contact with the adjacent ring of larger diameter or the body 220. Thus, the first ring 261 and the second ring 262 bear against the needle 210. Consequently, the retention system 250 provides a second equivalent engaged surface to compensate for the aerodynamic force, with a radius equal to the radius of the third seal 273. Therefore, 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 or first position.Indeed, the aerodynamic force in the second position pushes the needle further forward towards the nozzle throat than in the first position. Therefore, the force generated by the retention system must be greater in order to better retain the needle and facilitate a possible return to the first position.

[0100] The transition from the initial configuration to the first configuration of the nozzle 200 is achieved 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 achieved 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 achieved by moving the needle, the chamber pressure Pchamber of the chamber 240 allowing the rings 261, 262 to be pressed 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 achieved by moving the needle, the chamber pressure Pchamber of the chamber 240 allowing the second ring 262 to be pressed against the adjacent ring of larger diameter or the passage surface 222 and allowing the first ring 261 to be pressed 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] Figure 9 illustrates an example of a 300 nozzle with a gas ejection section 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 throat 321. The needle 310 is movable relative to the nozzle throat 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 coincide or at least partially coincide with the nozzle body. The body 320 may be distinct from the nozzle body. The body 320 comprises a flow surface 322 opposite the gas ejection section along the axis of displacement X. The passage surface 322 includes an orifice 323 extending along the axis of displacement X. The orifice 323 has a cylindrical shape of revolution about 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 includes a main surface 324 connecting the nozzle throat 321 to the passage surface 322. The main surface 324 of the body 320 extends along the direction of displacement X around the needle 310.

[0104] An actuator 330 actuates the needle 310 in translation along the axis of movement X. The actuator 330 can be positioned on the side delimited by the passage surface 322 opposite to the gas ejection section. The needle 310 is movable between several positions along the axis of movement 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 Sp gas ejection section

[0106] Figure 9 illustrates the nozzle 300 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 that is 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 that is 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 axis of movement X. The proximal portion 311 may be directly adjacent to the distal portion 312 along the axis of movement 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 partial occlusion of 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 distal portion 312 of the pointer 310 can present 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 chamber pressure representative of the pressure of the gas(s) coming from the combustion chamber.

[0110] The proximal portion 311 of the pointer 310 includes a stop 313 extending circumferentially around the axis of movement 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 axis of movement X. The number of stop surfaces 3131, 3132, 3133 can correspond to the number of rings in 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 pointer 310. The further the stop surface is from the distal part 312 of the pointer 310, the larger its radius.

[0111] A first stop surface 3131 is located at a first axial position on the axis of the pointer 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 pointer 310, the second axial position being further from the distal part 312 of the pointer 310 than the first axial position. Thus, the second stop surface 3132 is recessed 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 stop surface 3133 is located at a third axial position on the axis of the pointer 310, this third axial position being further from the distal part 312 of the pointer 310 than the second axial position. Thus, the third stop surface 3133 is set back relative to the second stop surface 3132. The third stop surface 3133 has a third radius that is larger than the second radius. The third stop surface 3133 is intended to be in contact with the third ring 363 when the third ring 363 is in contact with the stop 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 axis of movement X. The retention system 350 is located 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 axis of movement X. The first side 351 of the retention system 350 is positioned opposite the passage surface 322 of the body 320. The second side 352 of the retention system 350 is positioned 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 radially exhibits an 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 n seals and n+1 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 wear on the seals 371, 372, 373 is reduced.

[0116] In the example illustrated in [Fig. 9], the retention system 350 comprises four rings and three seals. It is of course still within the scope of the third embodiment of the invention if the retention system 350 comprises only two seals. Nor is it within 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 larger 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 larger 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 larger 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 along the radial direction (excluding shoulder) can be between 10% and 100% of the thickness of the seals along 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 on the second side 352. The shoulder 361a, 362a, 363a extends perpendicularly to the axis of movement X. The shoulder 361a, 362a, 363a is configured to be in contact with the adjacent ring of larger 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 include 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 allows the nozzle 300 to be placed 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 includes a shoulder 361a as described above. 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 supported by the body 220. Thus, no ring 361, 362, 363 is supported by the needle 310.If the needle 310 includes an "initial" annular seal on the outside of its proximal part 311, the retention system 350 provides an equivalent initial engaged surface to compensate for the aerodynamic force, having a radius equal to the radius of the "initial" seal. Thus, the force generated by the retention system 350 when the needle is in the initial position is very low.

[0123] When the pointer 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 larger diameter or with the body 320. The shoulders 362a, 363a of the other rings 362, 363 are in contact with the adjacent ring of larger diameter or with the body 320. Thus, all the other rings 362, 363, 364 are directly or indirectly supported by the body 320. Thus, no ring other than the first ring 361 is supported by 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 much force in the opposite direction to the collar 121 so as not to hinder a subsequent movement of the needle towards the collar 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 the second ring 362 are no longer in contact with the adjacent ring of larger diameter or with the body 320. Thus, the first ring 361 and the second ring 362 are bearing against the needle 310. Consequently, the retention system 350 provides a second equivalent engaged surface to compensate for the aerodynamic force, having for radius the radius of the second joint 372. Therefore, the second equivalent engaged area is larger than the first equivalent engaged area.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 forward more towards the nozzle throat than in the first position. Therefore, the force generated by the retention system must be greater in order to better retain the needle and facilitate a possible return to the first position.

[0125] When the pointer 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 other ring(s) 364 are at a non-zero distance from the stop 313. The shoulders 361a, 362a, 363a of the first ring 361, the second ring 362, and the third ring 363 are no longer in contact with the adjacent ring of larger diameter or with the body 320. Thus, the first ring 361, the second ring 362, and the third ring 363 bear against the point 310. Consequently, the retention system 350 provides a third equivalent engaged surface to compensate for the aerodynamic force, with a radius equal to the radius of the third seal 373. Therefore, 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 throat than in the second position. Therefore, the force generated by the retention system must be greater in order to better retain the needle and facilitate a possible return to the second position.

[0126] The transition from the initial configuration to the first configuration of the nozzle 300 is achieved 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 achieved 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 achieved 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 achieved by moving the needle, the chamber pressure Pchamber of the chamber 340 allowing the rings 361, 362, and 363 to be pressed against the stop 313, until the shoulder 363a of the third ring 363 is stopped by the adjacent ring of larger diameter or by the body 320. The transition from the second configuration to the first configuration of the nozzle 300 is achieved by moving the needle, the chamber pressure Pchamber of the chamber 340 allowing the third ring 363 to be pressed against the adjacent ring of larger diameter or against the body 320 and allowing the rings 361 and 362 to be pressed against the stop 313, until the shoulder 362a of the second ring 362 is stopped by the adjacent ring of larger diameter or by the body 329. The transition from the first configuration to the initial configuration of nozzle 300 takes place by moving the needle, the pressure PChambre of the chamber 340 allows the second ring 362 to be pressed against the adjacent ring of larger diameter or the body 320 and allows 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 400 gas ejection section nozzle 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 throat 421. The needle 410 is movable relative to the nozzle throat 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 throat 421 to the surface of passage 422. The main surface 424 of the body 420 extends along the direction of displacement X around the pointer 410.

[0130] An actuator 430 actuates the needle 410 in translation along the axis of movement X. The actuator 430 can be positioned on the side delimited by the passage surface 422 opposite to the gas ejection section. The needle 410 is movable between several positions along the axis of movement 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 Si gas ejection section.

[0132] Figure 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 that is smaller than the first gas ejection section Si.

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

[0134] The needle 410 comprises a proximal portion 411 and a distal portion 412 opposite the proximal portion 411 along the axis of movement X. The proximal portion 411 can be directly adjacent to the distal portion 412 along the axis of movement 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 partial occlusion of 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 can 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 PChambre representative of the pressure of the gas(s) 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 axis of movement 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 axis of movement 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 axis of movement 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 can be flexible or rigid. The membranes perform a sealing 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 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 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 final ring 464 is attached to the body 420. The retention system 450 therefore comprises n membranes and n + 1 rings. The membranes 471, 472, and 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 still within the scope of the fourth embodiment of the invention if the retention system 450 comprises only two seals. Nor is it within 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 larger than the first diameter of the first ring 461. The third ring has a third diameter larger than the second diameter of the second ring 462. The fourth ring 464 has a fourth diameter larger 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 about the axis of movement 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 secondary portion(s) of the orifice 423 defines stopping portions of the passage surface 422 extending towards the axis of movement X.

[0145] The proximal portion 411 of the needle 410 includes a stop 413 extending circumferentially around the axis of movement X in a discontinuous manner. Thus, the stop 413 comprises one or more portions distributed circumferentially around the axis of movement 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 such that the portions of the stop 413 can slide within the secondary portions of the orifice 423.

[0146] The stop portions are intended to retain the rings which must not come to rest on 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 axis of displacement 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 can correspond to the number of membranes in 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 point 410. The further the stop surface is from the distal part 412 of the point 410, the larger its radius.

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

[0149] The proximal portion 411 of the pointer 410 further comprises at least one groove. The groove(s) extend lengthwise along the axis of movement X and circumferentially between the portions of the stop 413. Each groove in the distal portion 411 of the pointer 410 corresponds to an advance of the passage surface 422. The groove(s) in the distal portion and the stop portion(s) of the passage surface 422 are configured such 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 part 411 of the needle 410 can slide in the orifice 423 of the passage surface 422. The sliding is facilitated in the case where the distal part 411 includes several grooves and where the passage surface 422 includes 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 bearing against 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 collar 121 so as not to hinder a subsequent movement of the needle towards the collar 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 bearing against the needle 410. Therefore, the retention system 450 makes it possible to obtain a second equivalent engaged surface to compensate for the aerodynamic force, having as its radius the radius of the second membrane 472. Therefore, the second equivalent engaged area is larger than the first equivalent engaged area.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 forward more towards the nozzle throat than in the first position. Therefore, the force generated by the retention system must be greater in order to better retain the needle and 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 engaged surface to compensate for the aerodynamic force, having a radius equal to the radius of the third membrane 473. Consequently, the third equivalent engaged surface is larger than the second equivalent area involved.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 or second position. Indeed, the aerodynamic force in the third position pushes the needle more towards the nozzle throat than in the second position. Therefore, the force generated by the retention system must be greater in order to better retain the needle and facilitate a possible return to the second position.

[0154] The transition from the first configuration to the second configuration of the nozzle 400 is achieved 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 achieved 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 achieved by moving the needle, the chamber pressure Pchamber of the chamber 440 allowing the rings 461, 462, 463 to be pressed 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 achieved by moving the needle, the chamber pressure Pchamber of the chamber 440 allowing the third ring 463 to be pressed 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 500 nozzle with a gas ejection section 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 throat 521. The needle 510 is movable relative to the nozzle throat 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 throat 521 to the surface of passage 522. The main surface 524 of the body 520 extends along the direction of displacement X around the pointer 510.

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

[0159] Figure 11 illustrates the nozzle 500 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 ejection section of Sp gas

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

[0161] Figure 12 illustrates the nozzle 500 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 that is smaller than the first gas ejection section S1 and the second gas ejection section S2. The aerodynamic force is moderate in this configuration.

[0162] The needle 510 comprises a proximal portion 511 and a distal portion 512 opposite the proximal portion 511 along the axis of movement X. The proximal portion 511 may be directly adjacent to the distal portion 512 along the axis of movement 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 partial occlusion element for 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 traverses the passage surface 522. The proximal part 511 of the needle 510 passes through the orifice 523 of the passage surface 522. The distal part 512 of the needle 510 may have an axisymmetric shape.

[0163] The nozzle 500 further includes 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 PChambre representative of the pressure of the gas(s) 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 axis of movement 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 axis of movement 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 outer 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 against 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 includes 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 ends 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 axis of movement 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 framework of the fifth mode of The invention is implemented if the retention system 550 comprises only two or three rings. Nor does it fall outside 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 larger 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 larger 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 larger 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 about the axis of displacement 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 secondary portion(s) of the orifice 523 defines stopping portions of the passage surface 522 extending towards the axis of displacement X.

[0172] The proximal portion 511 of the needle 510 includes a stop 513 extending circumferentially around the axis of movement X in a discontinuous manner. Thus, the stop 513 comprises one or more portions distributed circumferentially around the axis of movement 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 such that the portions of the stop 513 can slide within the secondary portions of the orifice 523.

[0173] The stop portions are intended to retain the rings which must not come to rest on 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 ring shape extending discontinuously around the axis of displacement X. The stop surfaces 5131, 5132, 5133 are present on the portion or portions 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 pointer 510. The further the stop surface 5131, 5132, 5133 is from the distal part 512 of the pointer 510, the larger its radius.

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

[0176] The proximal portion 511 of the pointer 510 further comprises at least one groove. The groove(s) extend lengthwise along the axis of travel X and circumferentially between the portions of the stop 513. Each groove in the distal portion 511 of the pointer 510 corresponds to an advance of the passage surface 522. The groove(s) in 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 part 511 of the needle 510 can slide in the orifice 523 of the passage surface 522. The sliding is facilitated in the case where the distal part 511 includes several grooves and where the passage surface 522 includes several stop portions.

[0178] When the pointer 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 the rings 561, 562, 563, and 564 are aligned in the same axial position. Thus, the seal 570 is perpendicular to the X-axis of movement. The seal 570 therefore has a minimal surface area in the first configuration. Consequently, the retention system 550 provides a first equivalent surface area, corresponding to the surface area of ​​the seal 570. Thus, the force generated by the retention system 550 when the needle is in the first position is sufficiently low, which prevents adding too much force in the opposite direction to the neck 121 to the aerodynamic force exerted on the needle, so as not to impede 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 a different axial position 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 area in the second configuration than in the first configuration. Therefore, the 550 retention system makes it possible to obtain a second equivalent surface engaged to compensate for the aerodynamic effort, corresponding to the surface of the 570 joint.The second equivalent area engaged is larger than the first equivalent area engaged. Therefore, 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 forward more towards the nozzle throat than in the first position. Consequently, the force generated by the retention system must be greater to better retain the needle and facilitate a possible return to the first position.

[0180] When the pointer 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 thrust surface. The third thrust 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 in a first axial position. The second ring 562 is in a second axial position different from the first axial position. The other rings 563 and 564 are in a third axial position different from the first and second axial positions. The second axial position is an intermediate position between the first and third axial positions. 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 provides a third equivalent engaged surface to compensate for the aerodynamic force, corresponding to the surface area of ​​the seal 570. This third equivalent engaged surface is larger 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 and second positions. Indeed, the aerodynamic force in the third position pushes the needle forward more towards the nozzle throat than in the second position.Therefore, the force generated by the retention system must be greater in order to better retain the needle and facilitate a possible return to the second position.

[0181] The transition from the first configuration to the second configuration of the nozzle 500 is achieved 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 achieved 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 achieved by moving the needle, the chamber pressure Pchamber of the chamber 540 allowing the rings 561, 562, 563 to be pressed against the stop 513, until the second ring 562 is aligned with the larger diameter rings 563, 564. The transition from the second configuration to the first configuration of the nozzle 500 is achieved by moving the needle, the chamber pressure Pchamber of the chamber 540 allowing the first ring 561 to be pressed against the stop 513, until the first ring 561 is axially aligned with the other rings 562, 563, 564.

[0183] In all 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] Figure 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 beyond 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 chamber pressure PChambre of the chamber 640, which is representative of the pressure of the gas(s) exiting 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 previous embodiments of the invention, is present on the retention member 660 in this first variant. The passage surface 622 then includes 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] Figure 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 beyond 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 disposed 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(s) exiting 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 disposed inside the needle 710. Thus, the rings exerting a force on the retaining 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 retaining 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 outer surface of the needle 710 to slide. The passage surface 722 further includes 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 retaining element 760. The retaining element 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 previous embodiments of the invention.

[0192] Thus, the rings come to rest 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 embodiments of the invention described above, the rings may be made of metallic material. In all embodiments of the invention described above, the rings may be made of composite material.

[0194] In all embodiments of the invention described above, the seals may be made of elastomer. In all embodiments of the invention described above, the seals may 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 suffered 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 as the needle moves between the first and third axial positions. The force generated by the retention system increases in steps as the aerodynamic force decreases. Indeed, as soon as a new ring is in contact with the needle or the retention member, the force generated by the retention system increases by one step. There are as many steps as there are seals or membranes in the retention system. 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 may be a compromise to achieve satisfactory discretization of the generated force while maintaining sufficiently thick rings and seals for strength and proper force transmission. Therefore, for some applications, the number of seals or membranes may range from 3 to 5 for an optimal compromise.

[0197] By way of example, the dimensioning described below can be adopted in the first and third embodiments, including in the first and second variants, for a retention system with three elastomeric seals having an elongation capacity of 400% and a shear modulus of 0.2 MPa. In this dimensioning, the internal radii of the first, second, and third seals are 5.65 mm, 7.15 mm, and 8.65 mm, respectively. The stiffness of the first, second, and third seals, according to a strength of materials (SOM) 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 displacement direction X is 12.5 mm. The thickness of the rings along the radial direction DR is 0.5 mm.Such a dimensioning allows a needle stroke of 6 mm, i.e. 2 mm permitted per seal, under 10 MPa.

[0198] The resulting nozzle can be used for any type of system incorporating needle valves. In particular, the resulting nozzle can be used in propulsion systems, missiles, rocket engines, or launch vehicles with solid, liquid, or hybrid propulsion.

Claims

Demands

1. A nozzle (100) comprising a needle (110) for movable along an axis of displacement (X) relative to a body (120) comprising a nozzle throat (121) and defining an ejection chamber (140) for combustion gases to pass through, 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 needle retention system (150) having a first side (151) opposite the stop (113) and a second opposite side (152) in communication with the ejection chamber (140) and comprising 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 sealing gasket (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. Nozzle (100) according to claim 1, wherein the annular needle retention system (150) is arranged around the needle (110) and extends between the needle (110) and the body (120).

3. Nozzle (700) according to claim 1, wherein the annular needle retention system (750) is arranged 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, wherein 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 axis of movement (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), such 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) suitable for being traversed by the stop (113) during the movement of the needle (110).

7. Nozzle (300) according to claim 5, wherein the rings (362, 363) of the annular system (350) comprise a shoulder (362a, 363a) at the level of 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. Nozzle (500) according to claim 5 or 6, wherein the sealing gasket (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, wherein 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, wherein the annular needle retention system (150) comprises a first sealing gasket (171) interposed between the first ring (161) and the second ring (162) and a second sealing gasket (172) surrounding the second ring (162).

11. Nozzle (200) according to any one of claims 1 to 4, wherein the annular needle retention system (250) comprises at least a first sealing gasket (272) interposed between the first ring (261) and the second ring (262) and a second sealing gasket (273) surrounding the second ring (262), wherein the stop (213) is a flat surface perpendicular to the displacement axis (X) of the needle (210), the first ring (261) having a first length along the displacement axis (X) of the needle (210) and the second ring (262) having a second length along the displacement axis (X) of the needle (210) shorter 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 annular system retention of the needle (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 larger diameter or with the body (220).

12. 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 length 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, wherein the sealing joints (171, 172, 173) are made of elastomeric material or silicone.

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