GB2307721A

GB2307721A - variable area nozzle

Info

Publication number: GB2307721A
Application number: GB8403416A
Authority: GB
Inventors: Gerard Ernest Andre Jourdain; Marcel Robert Soligny
Original assignee: Societe Nationale dEtude et de Construction de Moteurs dAviation SNECMA; SNECMA SAS
Current assignee: Safran Aircraft Engines SAS
Priority date: 1983-03-16
Filing date: 1984-02-09
Publication date: 1997-06-04
Anticipated expiration: 2004-02-09
Also published as: GB8403416D0; GB2307721B; FR2732408A1; DE3409552C2; DE3409552A1

Description

1 A TURBO = ENGINE NOZZLE 2307721 The present invention relates to a

variable area nozzle.

for example for a turbo jet engine.

Co-pending Patent Application No. 83.06650 describes a nozzle which includes three annular assemblies of blades: an assembly of convergent blades, extended by an assembly of divergent blades, and an assembly of secondary blades termed OcoldO blades. lying outwardly of the convergent and divergent blades, but coaxially with the latter, so as to surround them. Linear actuators are regularly distributed around the outlet of the nozzle. and are respectively coupled at appropriate points on one convergent blade in two, in order to cause it to pivot with respect to the outlet of tne nozzle. This nozzle further comprises members for controlling the position of at least one 'cold' blade in two. with that of the corresponding convergent blade, and means for synchronising the pivotal motions of tne convergent blades. The bodies or cylinders of the various actuators are. on the one hand, pivoted on the annular edge of the outlet of the duct. and, on the other hand interconnected by transverse elements.

forming, with the bodies of the actuators. a polygonal or circular structure. coaxial with the edge of the 2 nozzle. and substantially rigid. The upstream edges of the convergent and of the cold blades are on the other hand pivoted on the bodies of the actuators themselves. of which the piston rods, extending in the upstream direction. each support a transverse rocking lever. having its two arms coupled to the corresponding convergent blade by appropriate linkages. Furthermore, the coupling linkages associated with two adjacent actuators of this prior nozzle assembly are interconnected by transverse synchronisation members, which extend between the two actuators. for example by tubular elements. each provided. at its two ends, with radially outer seats. respectively pivoted on the bodies of the two actuators.

is This latter arrangement ensures the synchronisation of the control actions of the piston rods of the actuators on the corresponding blades. The structure is relatively complex but the synchronisation function can be disturbed because of the clearances which can arise in certain of the linkages, for example because of differences in thermal expansion and/or of wear phenomena. Likewise, the control members of the cold blades to the convergent blades comprise complex linkages. with several pivots. of which the correct operation can be disturbed by the same phenomena.

3 Copending application 82.33116 likewise describes a convergent divergent nozzle of the type under consideration, in which the tranmsission means. inserted between the actuators and the corresponding convergent blades on the one hand, and synchronisation means for the pivoting of the convergent blades on the other hand, are formed by a single, castellated and annular, kinematic chain. Control levers are each pivoted by rods to the fixed structure of the nozzle and extend over the width of one of the convergent follower blades, parallel to the pivot axis of its edges. Control rods are each pivoted, through the intermediary of ball joints. at one end. on the adjacent end of one of the control levers, and, at its other end. on the adjacent edge of the convergent blade closest thereto so as to control its pivotal movements. In this kinematic chain. the numbers for the control and synchronisation of the various movements of the convergent blades thus form a relatively complex, nondemountable structure, which has substantially the hereinbetore described disadvantages.

European Patent Application EP 0033044 which was filed 25 by the Applicant 23 December 1980 for "A nozzle device for a turbo jet engine" also describes a nozzle in 4 which an annular element serves to support at the same time two annular assemblies of pivotal bladest as well as their control actuators. of which the rods. directed downstream of the nozzle. actuate the corresponding pivoting blades through the intermediary of the rocking levers. Closely adjacent arms of two adjacent rocking levers are interconnected by a synchronisation mechanism, likewise carried by a tubular element. These relatively complex structures also have the disadvantages already referred to.

According to the present invention a variable area nozzle comprising at least two annular and coaxial blade assembliesp one assembly being of convergent blades, the other assembly. of secondary blades lying outwardly of the convergent blades so as to surround them. linear actuators regularly distributed around the nozzle axis, and respectively coupled to one convergent blade in two, in order to cause it to pivot with respect to the said nozzle axis. members for controlling the position of at least one secondary blade in two with respect to that of the corresponding convergent blade, and means for synchronising the pivotal motions of the convergent blades, the bodies of the actuators being arranged to be pivotally mounted on the annular edge of the outlet of an associated duct.

and being interconnected by transverse elements forming. with the bodies of the actuators. a complete polygonal or circulari substantially rigid, structure, coaxial with the edge of the outlet of the associated duct, and upstream edges of the said convergent secondary blades being pivoted on the bodies of the actuators themselves. of which the piston rods extending from their upstream endst each carry a transverse rocking lever, having its two arms coupled to the corresponding convergent blade by appropriate linkages, the rocking levers having lengths such that their adjacent ends are coupled two by two, so as to form a secondary structure. either polygonal or circular, coaxial with tne first structure. but pivoted at the zone of the coupled ends of the rocking levers, and the secondary blades being directly connected to the convergent blades by links of fixed length.

The synchronisation of tne pivotal movements of the convergent blades is thus provided by the rocking levers carried by the piston rods of the control actuators. or in other words the synchronisation is effected owing to tne particular shape of the rocking leverst which form part of the control devices of the blades# this configuration enabling association of all the rocking levers in a polygonal or circular 6 structurey whichr for any position of the piston rods of the control actuators. lies entirely in a common plane, perpendicular to the axis of the nozzle.

Nozzles in accordance with the invention thus have a simple. economic and serviceable construction of the synchronisation means, since it employs particularly, in order to form the synchronisation means. the rocking levers which are provided to ensure control of the pivotal motions of the blades. The synchronisation effected is furthermore particularly effective since. for exampler the breakage or other failure of the piston rod of one control actuator. or even the breakage of one of the elements of the coupling linkage of one arm of a rocking lever with a convergent bladep will be substantially without effect on the said synchronisation, because the blade concerned will be held in the correct position at least by the associated linkage of the other arm of the corresponding rocking lever, which will be maintained in the same plane as the other rocking levers because of its cooperation with the two adjacent rocking levers. Finally. the direct control of the "cold" blades by the convergent blades. by links of fixed length. constitutes an important simplification with respect to nozzles of the same type. hereinbefore 7 known.

A nozzle embodying the invention will now be described. by way of exampler with reference to the accompanying 5 diagrammatic drawings, in which:

Figure 1 shows the upper half of the nozzles in partial section in an axial plane; Figure 2 shows a part of a development of an annular assembly formed by the convergent blades of the nozzle of Figure 1. including control actuatorsi as well as the transmission and synchronisation devices with which the actuators are associated; is Figures 3. 4 and 5 are fragmentary sectional views respectively on lines III-IIIr IV-W and V-V of Figure 2.

In Figure it a part is shown of the external wall 1 of the outlet of the duct (jet pipe) of a turbo jet engine. (not shown). As apparent in Figures 1 and 2. linear actuators, 2, are disposed externally of the outer wall 1. so that their respective axes lie in radial planes. such as that of Figure 1, and are regularly spaced around the periphery of the nozzle.

8 The various Figures show that the upstream end portion of each actuator 2 is provided with two lateral projections 21 and 212p which extend in substantially peripheral directions, on one side and the other of the body of the actuator. and of which the free ends engage with two bosses. 1A and 112 on the said external wall 1. through ball joints 31 and 312. Such securing devices could each be replaced by a clevis and flange pivotally mounted on this clevis.

Similarly. as is shown in Figures 2 and 5, the downstream part of each actuator 2 comprises two lateral projections 2ú and 24. the projection 2. d terminating at a clevis 4g. in which an eye 4ú engages thus extending the projection 2.a to the next adjacent actuator 2. Each eye 4ú, is engaged in a clevis 4g, and is connected thereto by a pin 5 (Figure 5), for example the shank of a bolt. The assembly formed by the downstream parts of the actuators 2. and their lateral projections 2.C and 2ú1 connected by the devices 4úr 4g and 5. form a first structure. coaxial with the outer wall 1 of the outlet of the duct, and rigid therewith. Depending upon the form of the lateral projections 2.c and 2jd of each actuator 2, this structure lies substantially in a first plane perpendicular to the axis of the nozzler with a shape 9 which is substantially polygonal as indicated in Figure 5. or it may also have a substantially circular shape.

A first assembly of convergent blades 6 is pivotally mounted on the downstream parts of the actuators 2. As apparent particularly in Figures 1. 2 and 4, each convergent blade 6 is pivoted to the downstream part of the body of the corresponding actuator 2r through two 10 bell-crank levers 7,a and 7D, which lie parallel to one another. Each of these levers 7ja and 712 is disposed in a plane substantially axially of the nozzle and each comprises a first arm. for example 7s11 and 7b, rigid with the corresponding convergent blade, 6, and a second arm 7ú12 and 7122 directed towards the outside of the nozzle (Figure 1). The two arms 7A1 and 7A2 or 7121 and 7D2 of each bell-crank lever 7A or 712 interconnect at an elbow. which itself is pivoted. by means of a pin 8, extending between the two levers 7A and 712. and by a tube 10. concentric with the said pin 8. on two seats. 911 and 91a, rigid with the downstream part of the actuator body 2. as shown in Figures 2 and 4.

25A second blade assembly, termed cold' blades. 11, lies outwardly of the convergent blades 6. and surrounds them. These cold' bladesi 11. have their upstream edge pivoted by pins 12ú, 12A (Figure 5)p engaged in corresponding clevises of the projections. 2.C and 2.d, rigid with the downstream part of the corresponding actuator 2. Each convergent blade 6 is also coupled to the corresponding cold blade. lli by a link 13 of predetermined length, of which one end is pivoted at 13& (Figure 1) adjacent to the elbow of the corresponding lever 712. and the other end. at 1312 on the corresponding cold blade 11.

A control extends from the upstream end of each actuator 2# 14. of which the free end forms a fork, 14Ar traversed by a radial pin 15. The median part of each rocking lever 16. with two equal arms. 16A and 1Q, is engaged in the fork 14A terminating the rod 14 of each actuator 2. so as to cooperate with the pin 15 through a ball-joint 17 (Figure 1).

The rocking levers 16 have their lengthso generally equal to one another. such that their adjacent ends can be coupled two by two; it will be seen in particular, at the lower left hand extremity of Figure 2, that the arm 1Q of the lower rocking lever 16 - which is only shown in part terminates at a pin 16ú. which is freely engaged in an aperture of a ball-joint 18, 11 itself rigid with the corresponding end 16.d. of the arm 16a of the upper intermediate rocking lever 16. owing. in particular, to the ball-joints such as 18. the various generally rectilinear rocking levers 16, lie in the sides of a polygon disposed in a second plane perpendicular to the axis of the nozzle.

The median parts of the arms 16k and 16J2 of each rocking lever 16 are coupledr by substantially radial pins 19A and 19b, to the first ends of the rods 20.a and 20J2 which are disposed parallel to the axis of the corresponding actuator 2; the second ends of the rods 20jj and 20D are respectively coupled, through the intermediary of ball-joints 21.&, 21J2 (Figure 4)f to the ends of a tube 22, itself rigid with second arms 7A2 and 7h2 of the two bellcrank levers 7.a and 7b rigid with the corresponding convergent blade 6.

When the piston rod 14 of each of the actuators 2 moves out of the body of the corresponding actuatori or returns thereinto. the fork 14A and the pin 15, mounted at the end of the rod 14 exerts, through the the ball joint 17. on the median part of the corresponding rocking lever 16, a force of substantially axial direction and directedi in accordance with the case, to the left or the right of Figures 1 and 2. This force 12 is transmitted to the corresponding rods. 201 and 20J2. associated with the actuator 2 under consideration, through the intermediary of pins 191 and 1912, and these rods 20Ai 2012 transmit the force from their other endsi through ball-joints 211 and 21ky respectively to the ends of the tubes 22. The latter pivons as a result about the pin 8. whilst causing the levers 71 and 712 to pivot in the same manner as the convergent blade 6 which is rigid therewithy in a sense which depends clearly on the sense of the force transmitted by the rods 201 and 20k. Under the action of the pivoting couple thus transmittedp the convergent blade 6 itself pivots aDout the pin 8.

Through the links 13, the pivoting movements of convergent blade 6 produce consequential pivoting movements of the corresponding cold blades 11, about their pivot axes 12.Q.

The pin 8 being held, by the tube 10 and the seats 9.a and 9.b, in a fixed position in a plane perpendicular to the axis of the nozzle. the tube 22 is itself held parallel to this fixed direction through the arms 7A2 and 7122 Of the levers 711 and 71a. Furthermore, the pivotal movements of the rocking levers such as 16, particularly about the pin 15 carried by the fork 14ú1 13 at the end of the piston rod 14 of the corresponding actuator 2, which will be eventually permitted by the ball-joints 21A and 21k interposed between the ends of tne tube 22 on the one hand, and the corresponding ends of the rods 20A and 2012F on the other hand. are substantially prevented by tne two by two coupling of the adjacent ends of the various rocking levers 16, because the parts 22, 20A, 2012 and the median part of the corresponding rocking lever 16 substantially form a non-deformable rectangle. As has already been indicated, the rocking levers 16 whatever may be the positions of the piston rods 14 of the various actuators 2. substantially conform to the edges of a polygon situated in a plane perpendicular to the axis of the nozzle. The accurate synchronisation between the pivoting movements of the convergent blades 6, which is thus effected. will not be disturbed even in the case of failure of the piston rod 14 of one of the actuators 2. or of one of the two control rods, 2011 and 20.b, with which they are associated. In fact, in the case of such a failure. the pivoting of the corresponding convergent blade 6 will still be effected, with a correct sense and amplitude, through the intermediary of the corresponding rocking levers 16 and of the or each of the rods 20A and 20121 because of the fact that the rocking lever 16 will continue to 14 participate in the movement of the assembly of the other rocking levers in a plane perpendicular to the axis of the nozzle.

In one modification the actuators 2 are constructed in accordance with Figures 9 and 10 of French Patent Application 81.21980. hereinbefore referred to so as to shield the sliding parts of each actuator from the forces and deformations to which its body can be subjected because it is incorporated in the rigid structure supporting the assembly of the elements of the nozzle. Although the present invention has been described as applied to a nozzle comprising only a first assembly of convergent blades and a second coaxial assembly of cold' blades. it can also be readily applied to a convergent-divergent nozzle, including a third assembly. of divergent blades.

is CliAILIS 1. A variable area nozzle, comprising at least two annular and coaxial blade assemblies, one assembly being of convergent blades. the other assembly, of secondary blades lying outwardly of the convergent blades so as to surround them, linear actuators regularly distributed around the nozzle axis and respectively coupled to one convergent blade in two. in order to cause it to pivot with respect to the said nozzle axist members for controlling the position of at least one secondary blade in two with respect to that of the corresponding convergent blade, and means for synchronising the pivotal motions of the convergent bladest the bodies of the actuators being arranged to be pivotally mounted on the annular edge of the outlet of an associated duct, and being interconnected by transverse elements forming, with the bodies of the actuators. a complete polygonal or circular, substantially rigid. structurey coaxial with the edge of the outlet of tne associated duct. the upstream edges of the said convergent secondary blades being pivoted on the bodies of the actuators themselves, of which the piston rods extending from their upstream ends. each carry a transverse rocking lever, having its two arms coupled to the corresponding convergent blade 16 by appropriate linkagesp the rocking levers having lengths such that their adjacent ends are coupled two by two. so as to form a secondary structure. either polygonal or circular,, coaxial with the first structure. but pivoted at the zone of the coupled ends of the rocking levers and the secondary blades being directly connected to the convergent blades by links of fixed length.

2. A nozzle according to claim 1, wherein each convergent blade coupled with one of the actuators is pivoted on the body of the said actuator through at least one bellcrank lever disposed in a substantially axial plane of the nozzle and comprising a first arm rigid with the said convergent bladean elbow pivoted, at least by a pin to the end of a seat rigid with the downstream part of the body of the actuator and a second arm directed outwardly of the nozzle.

3. A nozzle according to claim 2, comprising two said bellcrank levers lying parallel to one another and associated with a common convergent blade, have their second arms coupled by a tubular element or other transverse member freely passing between the corresponding convergent and secondary blades. and downstream of the body of the actuator coupled to the 17 said convergent blade.

4. A nozzle according to claim 3, wherein each coupling linkage of one arm of each rocking lever with a convergent blade comprises a rod. of which the ends are respectively coupled to the corresponding arm of the rocking lever by a radial pin and at the corresponding end of the tubular element through a ball-joint.

5. A variable area nozzle substantially as hereinbefore described with reference to the accompanying drawings.

6. A turbo-jet engine comprising a variable area nozzle according to any one of the preceding claims.

1 Amendments to the claims have been filed as follows 1 - A variable area nozzle, comprising at least two annular and coaxial blade assemblies, one assembly being of convergent blades, the other assembly,, of secondary blades lying outwardly of the convergent blades so as to surround Ch em, linear actuators regularly distributed around the nozzle axis and respectively coupled to one convergent blade in two. in order to cause it to pivot with respect to the said nozzle axis, members for controlling the position of at least one secondary blade in two with respect to that of the corresponding convergent blade, and means for synchronising the pivotal motions of the convergent blades, the bodies of the actuators being arranged to be pivotally mounted on the annular edge of the outlet of an associated duct, and being interconnected by transverse elements forming, with the bodies of the actuators, a complete polygonal or circular, substantially rigid, structure, coaxial with the edge of the outlet of the associated duct, the upstream edges of the said secondary blades being pivoted on the bodies of the actuators themselves, of which the piston rods extending from their upstream ends, each carry a transverse rocking lever, having its two arms coupled to the corresponding convergent blade c 19 by appropriate linkages, the rocking levers having lengths such that their adjacent ends are coupled two by two, so as to form a secondary structure, either polygonal or circular, coaxial with the first structure, and being piv otally connected at the coupled ends of the rocking levers and the secondary blades being directly connected'to he convergent blades by links of fixed length.

2. A nozzle according to claim 1, wherein each convergent blade coupled with one of the actuators is pivoted on the body of the said actuator through at least one bellcrank lever disposed in a substantially axial plane of the nozzle and comprising a first arm rigid with the said convergent blade an elbow pivoted, at least by a pin to the end of a seat rigid with the downstream part of the body of the actuator and a second arm directed outwardly of the nozzle.

3. A nozzle according to claim 2, comprising two said bellerank levers lying parallel to one another and associated with a common convergent blade, have their second arms coupled by a tubular element or other transverse member freely passing between the corresponding convergent and secondary blades, and downstream of the body of the actuator coupled to the said convergent blade.

4. A nozzle according to claim 3. wherein each coupling linkage of one arm of each rocking lever with a convergent blade comprises a rod, of which the ends are respectively coupled to the corresponding arm of the rocking lever -by a radial pin and at the corresponding end of the tubular element through a ball-joint.

5. A variable area nozzle hereinbefore described with accompanying drawings.

substantially as reference to the 6. A turbo-jet engine comprising a variable area nozzle according to any one of the preceding claims.