FR3080895A1 - METHOD AND SYSTEM FOR MAINTAINING BISTABLE BLADE OF A SHAFT ACCORDING TO TWO STATE POSITIONS - Google Patents

Abstract

The invention relates to a method and a blade retention system of a rotary shaft (4), comprising a bistable thrust mechanism having two stable angular positions (P1, P2) and coupled to transverse ends respectively to a workpiece interface and a lever mounted on the rotary shaft (4). In such a system, the bistable thrust mechanism (10) comprises one or more flexion-compression-deformable blades (10a, 10b) according to pre-deformed states corresponding to one and the other of the stable positions (P1, P2 ). In addition, each blade (10a, 10b) has ends or end zones attached to the interface piece (2) and the lever (3) by end pieces pivotally mounted on the interface piece (2). and on the lever (3) parallel to the rotary shaft (4).

Description

METHOD AND SYSTEM FOR HOLDING A BISTABLE BLADE OF A SHAFT ACCORDING TO TWO STATE POSITIONS

DESCRIPTION

TECHNICAL FIELD The invention relates to a method and a system for holding a bistable blade of a rotary shaft of equipment in positioning according to two positions, corresponding to so-called equipment status positions, particular of the opening / closing or locking / unlocking states.

The invention relates in particular but not exclusively to the field of aeronautics, and more particularly aircraft doors which are equipped with numerous mechanisms for rotating shafts between two state positions corresponding to two opposite states of the mechanism : latch mechanism (“latch” in English terminology) for opening / closing the door, locking / unlocking mechanism (“lock” in English terminology) for the latch, arming / disarming control mechanism for the door slide, mechanism for securing / releasing the hinge arm of an emergency door "on the wing" ("overwing" in English terminology), etc. These mechanisms allow the use of aircraft doors under normal conditions and in emergencies, while ensuring the safety requirements imposed by certification standards.

However, the invention can be applied generally in any field (building, automobile, rail, maritime, etc.) where an item of equipment has a shaft having two state positions.

These mechanisms include a guided pushing means - a spring or jack rod - provided at its ends with fixed and movable articulation ball joints, respectively with a so-called interface part, linked to the structure or constituting a part fixed to the door, and with a lever - called "guignol" secured in rotation to the shaft.

Figure 1 schematically illustrates by a side view the stable positions P1 and P2 of a rod mechanism 1b mounted on an interface part 11 secured to a door structure S1. These stable positions P1 and P2 of the mechanism 1b correspond to two state positions of a shaft 4. To move the shaft 4 from one position to the other, the mechanism 1b passes through an unstable intermediate position PO (symbolized by a dotted line). In this position PO, the longitudinal axis ΥΎ of the mechanism 1b, which joins the center of the ball joints R1 in a fixed relative position and R2 in mobile articulation (respectively connecting the connecting rod "B" to the interface part 11 and to the horn. G1), goes through the axis X'X of rotation of the shaft 4.

In this PO position, the rod "B" has maximum compression. To reach one or the other of the stable positions P1 or P2, the horn G1 and the shaft 4 rotate respectively around the axis X'X of the shaft 4 according to the arrow F1 or F2. Guignol G1 thus provides a lever arm to the force of the connecting rod "B" which then exerts a moment on the axis of rotation X'X of the shaft 4. And the ball joints R1 and R2 make it possible to guarantee the alignment of the pushing means "B" with the interface part 11 on the one hand and the horn G1 on the other hand.

The two stable positions P1, P2 and the unstable intermediate position PO of the spring rod mechanism 1b mounted on the part 11 secured to the door structure S1 are also shown in the views of diagrams 2a to 2c of FIG. 2 In position P1 (diagram 2a) and P2 (diagram 2c), the axis ΥΎ of the connecting rod mechanism 1b joining the ball joints R1 and R2 does not pass on the axis X'X of rotation of the shaft 4 so that be able to exert a moment of thrust on shaft 4 via the horn G1. In the intermediate unstable equilibrium position PO (diagram 2b), the axis ΥΎ passes through the axis of rotation X'X of the shaft 4 and, the lever arm having zero offset, the moment of rotation is also zero .

STATE OF THE ART [0008] The use of such jack or spring push mechanisms, making it possible to stabilize the shaft according to two defined angular positions corresponding to two states of a piece of equipment, is used in many patent documents, for example US 4,639,021, US 5,577,781 or US 2018001997.

However, the use of such pushing means has many drawbacks: an internal guide is necessary in the pushing mechanism in order to avoid any lateral buckling due to axial compressions, the pushing mechanism is liable to become fouled. which increases the efforts to pass from one state to another of the equipment, need for at least one ball joint to guarantee the alignment and the guiding of the pushing mechanism, high mass and complexity of the mechanism, or even wear of the cylinders (leaks, aging, etc.) with loss of reliability of the mechanism.

PRESENTATION OF THE INVENTION The invention aims to eliminate the drawbacks of the state of the art by involving an unguided pushing mechanism. To do this, the invention provides a bistable source of thrust in the form of at least one deformable blade between two stable positions allowing a shaft linked to this source to pivot, in an unguided manner, between two predefined angular positions corresponding to two conditions of the equipment using this tree.

More specifically, the present invention relates to a method of holding a bistable blade of a rotary shaft between a first and a second position. A bistable deformable pushing mechanism being by transverse coupling at the ends of this mechanism to an interface piece and to a lever mounted on the rotary shaft around an axis, this method consists in:

position the shaft in the first stable position, in which the or each blade of the blade mechanism works in flexion in a pre-deformed state generating a thrust against the interface piece and the lever, the mechanism having ends being placed in a transverse plane making a given angle with a reference plane passing through the axis of rotation of the shaft and the connection of the mechanism to the interface part;

- rotate the shaft against the thrust exerted by the blade mechanism to reach an intermediate position in maximum blade compression, in which the transverse plane coincides with the reference plane; this intermediate position preferably corresponds to a passage of symmetrical curvature in the case of a blade or to symmetrical curvatures in the case of at least one pair of blades; and

- let the rotation of the shaft continue by driving under the impulse of the thrust exerted by the blade mechanism from the intermediate position, until reaching the second stable position in which the or each blade works in bending according to a pre-deformed state generating the same thrust between the ends as that exerted in the first stable position; in this second position, the transverse plane can make an angle with the reference plane of value opposite to that corresponding to the first stable position, the pre-deformed state and the thrust exerted in the second stable position can be symmetrical with the pre-deformed state and the thrust exerted in the first stable position.

Thus, the invention uses deforming blades in flexioncompression as a means of energy storage and restitution: the deformation energy is returned in the form of thrust acting on the lever to reach the second stable position.

According to particular embodiments, at least one end of the blade mechanism is rotatably or pivotally mounted on an axis of the interface part and / or on an axis of the lever, parallel to the rotary shaft. The end (s) of the blade mechanism which are not mounted in rotation or in pivoting are mounted in fixed connection with the interface piece and / or the lever.

The invention also relates to a blade holding system of a rotary shaft for implementing the above method, comprising a bistable pushing mechanism having two stable angular positions and coupled at transverse ends respectively to a workpiece interface and a lever mounted on the rotary shaft. In this system, the bistable pushing mechanism comprises one or more deformable blades in flexion-compression according to pre-deformed states corresponding to one and the other of the stable positions. In addition, each blade has ends or end zones fixed to the interface part and to the lever by end pieces mounted in rotation or in pivoting on the interface part and on the lever parallel to the rotary shaft.

Advantageously, the invention uses a minimum number of parts, which makes the system lighter and more reliable. The invention does not use any part which slides over each other: the risk of wear, fouling or jamming is therefore significantly reduced. In addition, the invention can accept a slight offset of the ends of the pushing mechanism, which makes it possible to get rid of the ball joints and therefore to obtain a significant gain in mass.

Thus, the holding system according to the invention does not contain any fluid or gas which risks aging prematurely and therefore generating maintenance problems during the life of the equipment, in particular a door of aircraft. Advantageously, the system according to the invention can be defined and manufactured in a standard manner, without creating a specification plan.

Preferably, the paired blades have reverse curvatures of the same absolute value - that is to say of opposite signs - when one blade is compared to the other of the same couple in one or the other stable positions.

According to advantageous embodiments:

- at least one of the attachment points of the blade mechanism is mounted on an axis of rotation, parallel to the rotary shaft;

- when the attachment end of the blade mechanism is mounted on an axis of rotation of the lever parallel to the rotary shaft, this axis of rotation is mounted on extensions of the lever extending perpendicular to the rotary shaft;

- the blade mechanism comprising a single blade, the attachment of the blade ends to the lever and to the interface part is carried out by means chosen between a rotational mounting on an axis parallel to the axis of the rotary shaft , an attachment to a tip area and pivoting by wedging between two faces of a dihedral;

- the faces of the dihedron for pivotally mounting the blade end have a surface of curvature chosen between plane and convex;

- the blade mechanism comprising at least one pair of blades, each pair is fixed at its transverse ends on end pieces mounted in rotation on axes parallel to the rotary shaft;

the blade mechanism comprising at least one pair of blades, at least one elastic link joins the blades of each pair at points or portions located at equal distance from the ends of these blades, so as to limit the deflection between the blades, increase the thrust exerted by the blades and reduce the mechanical stresses in the blades;

- The elastic link consists of means chosen from at least one helical spring, at least one elastic band, and a combination of spring and elastic band. Advantageously, the elastic band can be in the form of a block having a thickness equal to the width of the blades which it joins.

PRESENTATION OF THE FIGURES Other data, characteristics and advantages of the present invention will appear on reading the following non-limited description, with reference to the appended figures which represent, respectively:

- Figures 1 and 2, views of different positions of a connecting rod guided mechanism according to the prior art, articulated on an aircraft door interface and a rotary shaft via ball joints (already commented);

- Figure 3, a perspective view of an exemplary holding system according to the invention comprising a mechanism with two blades articulated at the ends on transverse axes of rotation of a structure interface and a lever mounted on the 'rotary shaft;

- Figure 4, front views of the holding system of Figure 3 according to two angular positions corresponding to the stable positions of the blade mechanism (views 4a and 4c), as well as according to the intermediate position of unstable equilibrium (view 4b) moving from one stable position to another;

- Figure 5, partial front views of a holding system of the type of the previous figure, equipped with a spring (diagram 5a), several springs (diagram 5b) and an elastic band (diagram 5c) to limit deflection between the blades;

- Figure 6, front views of another example of a holding system according to the invention with a single blade in two angular positions corresponding to the stable positions of the blade mechanism (views 6a and 6c), as well as in the intermediate position unstable equilibrium (view 6b) of passage between the stable positions;

FIGS. 7 and 8, side views of variant holding systems according to the invention comprising a mechanism with two pairs of blades (FIG. 7) and with a single blade (views 8a and 8b), and

- Figure 9, perspective views of other variants of the cascade support system, comprising a single blade mechanism and or two coupled blades.

DETAILED DESCRIPTION In the present text, the qualifier "transversely" or "transverse" relates to a blade direction according to its width, perpendicular to its longitudinal direction, this transverse or transverse direction being parallel to the rotary shaft. Furthermore, a pre-deformed state of a blade is determined by a prestressed flexion state between the ends of this blade defining a blade configuration.

Referring to the perspective view of Figure 3, an example of a holding system 100 according to the invention comprises a mechanism with a bistable blade 10 riveted to the first blade ends 10e of the blades 10a, 10b to the first end pieces 11 mounted in rotation on a transverse axis A'A crimped on a base 21 of an interface part 2 fixed to an aircraft door (not shown).

The other ends 10 'of the blades 10a, 10b of the blade mechanism 10 are riveted to second end pieces 12 mounted in rotation on a transverse axis B’B. The ends 10e and 10e ’of the blades 10a, 10b are joined to the end fittings 11 and 12 which form the ends of the blade mechanism 10.

The transverse axis B’B is arranged between two extensions 13 of a lever 3 engaging on the rotary shaft 4 (seen in transparency). These extensions 13 extend perpendicular to the rotary shaft 4, the transverse axis B’B remaining parallel and at a distance from the shaft 4 of axis X’X.

The blade mechanism 10 consists more precisely of two metal blades 10a, 10b deformable in bending-compression and having opposite curvatures. The blades 10a and 10b are secured at their ends to the tips 11 and 12 by rivets 5. Alternatively, the blade mechanism 10 can be secured to the tips 11 and 12 by other means, for example by welding or gluing.

Referring to the front views of Figure 4, the example of the holding system 100 of Figure 3 appears in a first P1 (view 4a) and a second P2 (view 4c) stable positions, corresponding respectively to a state position of the shaft 4, as well as according to the intermediate position of unstable equilibrium PO (view 4b) for passing from one stable position to the other.

In view 4a, the blades 10a and 10b are in symmetrical bending (same curvature of opposite sign) according to pre-deformed states generating a thrust between the ends of the mechanism with bistable blade 10 which come together in a transverse plane Pt passing through the transverse axes of rotation A'A and B'B. The transverse plane Pt is inclined at an angle "+ A" relative to a reference plane Ps passing through the transverse axis of rotation A'A of the interface piece 2 and the axis X'X of the tree 4.

The operator rotates the shaft 4 using a handle (not shown) which transforms the thrust exerted by the blade mechanism 10 into kinetic impulse. The system 100 reaches the unstable intermediate position PO illustrated by view 4b. The blades 10a and 10b are then in maximum compression - according to the same curvature of opposite sign - and the axis X'X of the rotary shaft 4, the transverse axis B'B of the lever 3, as well as the transverse axis A'A of the interface part 2 are aligned in the reference plane Ps. The transverse plane Pt coincides with the plane Ps which then constitutes an axis of symmetry for the system 100.

The system 100 does not remain in the unstable intermediate position PO of compression of the blades 10a, 10b but relaxes by the dynamic impulse induced by the rotation of the shaft 4. The system 100 then pivots until it reaches the position stable P2 of view 4c. In position P2, the blades 10a and 10b return in symmetrical bending according to the same pre-deformed states as in the first stable position P1 (view 4a), generating symmetrical thrusts on either side of the transverse plane Pt. The transverse plane is then inclined by an angle "-A" relative to the reference plane Ps, according to the same amplitude as in the initial position P1 (view 4a) but of opposite sign.

Advantageously, as illustrated by the front views 5a to 5c of Figure 5, the bistable blade mechanism with two blades 10 of the holding system 100 'is equipped with a central spring 6 (view 5a), the ends are joined on middle portions 1m, 1n of the blades 10a, 10b, or of several springs 6a, 6, 6b (view 5b) joined at the end on intermediate portions - respectively 1t, 1m, 1v and 1y, 1 n, 1z - blades 10a, 10b located at equal distance from the ends of the blades. Alternatively, an elastic block 7 (view 5c) of thickness substantially equal to the width of the blades 10a, 10b is mounted between these blades. These spring or elastic band means such as the block 7 make it possible to limit the deflection, that is to say the spacing, between the blades 10a and 10b articulated on the transverse axes of rotation A'A and B'B respectively of the interface piece 2 ′ and of the lever 3 ′ (having alternative shapes to the interface piece 2 and to the lever 3 of FIGS. 3 and 4).

Another embodiment of the holding system 101 according to the invention is illustrated by the front views 6a to 6c in FIG. 6, according to the positions P1, PO and P2 of the example in FIG. 4. The holding system 101 differs from systems 100 or 100 'in that the bistable blade mechanism 14 now consists of a single blade 10c wedged in at the end edge 14e and glued to another end zone 14e', respectively on the edge 2a of the interface part 20 and in an end slot 3a of the lever 30. Alternatively, the end zone 14 e 'can be riveted or welded in the slot 3a.

The edge 2a belongs to a dihedral 2d formed on the interface part

20. The axis X'X of the rotary shaft 4 and the edge 2a are aligned in the reference plane Ps and the visible end lines 14e and 14f (of the end zone 14e ') of the blade 10c are aligned in the transverse plane Pt.

In the first stable position P1 (view 6a), the blade 10c is in flexion according to a pre-deformed state of given curvature, generating a thrust between its end 14e and its end line 14f. The blade 10c is supported on a face F3 of the dihedral 2d. The planes Pt and Ps form an angle + A ’, similar to the two-blade mechanism 10 (cf. FIG. 4, view 4a).

The operator rotates the shaft 4 until reaching the unstable intermediate position PO illustrated in view 6b. The blade 10c is in maximum compression - according to the same curvature of opposite sign - and the axis X'X of the rotary shaft 4, the end zone 14e 'and the edge 2a of the interface part 20 ( coinciding with the end edge 14e of the blade 10c) are then aligned in the transverse plane Pt coinciding with the reference plane Ps (which then constitutes an instantaneous plane of symmetry). The blade 10c which follows the rotation of the shaft 4 changes its curvature (change indicated by the dotted line of the blade 10c in view 6b).

The system 101 then switches to the second stable position P2 (view 6c) under the expansion of the blade 10c induced by the dynamic impulse of the rotation of the shaft 4. In position P2, the blade 10c returns to bending according to a pre-deformed state of symmetrical curvature of that defined in the first stable position P1 (view 4a), and the blade 10c then bears on the other face F4 of the dihedral 2d. The planes Pt and Ps form an angle - A ’, in the same way as in the case of the two-blade mechanism 10 (cf. FIG. 4, view 4c).

Variants of the previous examples of holding systems according to the invention are illustrated in Figures 7 and 8. With reference to Figure 7, the bistable blade mechanism 15 of the system 105 comprises two pairs of blades 15a, 15b and 15c, 15d mounted on the transverse axis B'B of the lever 3 'and on the axis A'A of the interface part 2' illustrated previously in FIG. 5.

In view 8a of Figure 8, a mechanism 16 with a single blade 10c as illustrated in Figure 6, is mounted in an end region 16e in a slot 2f of a tip 22 rotating on the 'axis A'A of the interface piece 2 ”(variant form of the interface piece 2'). In its other end region 16e ', the blade 10c is in abutment on one or other of the faces F5, F6 of a transverse dihedral 2d' integrated into the lever 3 ”, the end edge 16b being mounted in wedge on the edge 2a 'of the dihedral 2d'. The mechanism with a singleOlc blade, the 3 "lever and the 2" interface piece form the holding system 106.

In view 8b, the holding system 107 differs from the holding system 106 of the view 8a in that the blade 10c is mounted in abutment on one or the other of the convex faces F7, F8 of a dihedral 2d ”formed by the interface piece 20 ', by wedging the blade end 17e on the edge 2a”, and in that the planar faces of the dihedron 2d' are replaced by convexes F'5, F '6.

Perspective views of other variants of the holding system according to the invention are illustrated in cascade in FIG. 9. The holding systems 108 to 110 include mechanisms 10x to 10z with a single blade 10c mounted on a lever 31 and on the interface part 2 (cf. FIG. 4).

In these mechanisms, the blade 10c is fixed to the lever 31 by its end zone 18 sandwiched between plates 31a, 31b of the lever 31. And in its other end zone 19, the blade 10c is fixed in rotation on the transverse axis A'A of the interface part 2 (system 108, mechanism 10x), or is fixed by sandwich riveting between plates 32a, 32b (systems 109 and 110, mechanisms 10y and 10z) .

The holding system 111 derives from the system 100 illustrated in FIG. 3. In this system, the mechanism with two blades 10 'is mounted on the transverse axis B'B via a single extension 13 of the lever 3 and in rotation on the axis A'A of the interface part 2. The blades 10'a and 10'b are formed of rigid linear parts articulated elastically on median portions 1'm and 1'η.

The invention is not limited to the embodiments described and shown. In particular, the number of blades of the system is not limited to one or two pairs, but may include several pairs of blades mounted in rotation at their ends on transverse axes.

Furthermore, the means for limiting the deflection between the blades can combine one or more springs with elastic bands.

In addition, the stable positions may not be symmetrical with respect to the reference plane.

In addition, the mounting of the single blade on the lever can also be carried out in rotation around an axis parallel to the axis of the rotary shaft.

Claims (12)

1. A method of holding a bistable blade of a rotary shaft (4) between a first (P1) and a second position (P2), in which a bistable deformable pushing mechanism is connected by transverse coupling at the ends of this mechanism to an interface part (2) and a lever (3) mounted on the rotary shaft (4) around an axis (X'X), characterized in that it consists of: - install one or more blades between the ends (11, 12; 2a, 3a; 22, 2a '; 2a ”; 19, 31a, 31b; 32a, 32b) of the pushing mechanism to constitute a blade mechanism (10, 10 ', 14 to 17, 10x to 10z); - position the shaft (4) according to the first stable position (P1), in which the or each blade (10a, 10b; 10c; 10'a, 10'b; 15a to 15d) of the blade mechanism (10, 10 ', 14 to 17, 10x to 10z) works in flexion in a pre-deformed state generating a thrust against the interface piece (2, 2', 2 ”, 20, 20 ') and the lever (3, 3' , 3 ”, 30, 31), the mechanism (10, 10 ', 14 to 17, 10x to 10z) having ends (11, 12; 2a, 3a; 22, 2a'; 2a”; 19, 31a, 31b ; 32a, 32b) being placed in a transverse plane (Pt) making a given angle (+ A) with a reference plane (Ps) passing through the axis of rotation (X'X) of the shaft (4) and the connection of the mechanism (10, 10 ', 14 to 17, 10x to 10z) to the interface piece (2, 2', 2 ”, 20, 20 '); - rotate the shaft (4) against the thrust exerted by the blade mechanism (10, 10 ', 14 to 17, 10x to 10z) to reach an intermediate position (PO) in maximum blade compression (10a, 10b ; 10c; 10'a, 10'b; 15a to 15d), in which the transverse plane (P _T ) coincides with the reference plane (Ps); and - let the rotation of the shaft (4) continue by driving under the impulse of the thrust exerted by the blade mechanism (10, 10 ', 14 to 17, 10x to 10z) from the intermediate position (PO ), until reaching the second stable position (P2) in which the or each blade (10a, 10b; 10c; 10'a, 10'b) works in flexion in a pre-deformed state generating a same thrust between the ends (10th, 10th ') than that exercised in the first stable position (P1). 2. A holding method according to claim 1, in which the intermediate position (PO) corresponds to a passage of symmetrical curvature in the case of a blade (10c) or to symmetrical curvatures in the case of at least one pair of blades (10a, 10b; 10'a, 10'b; 15a to 15d), the transverse plane (P _T ) making in the second position (P2) an angle (-A) with the reference plane (Ps) of value opposite to that corresponding to the first stable position (PO), the pre-deformed state and the thrust exerted in the second stable position (P2) being symmetrical with the pre-deformed state and the thrust exerted in the first stable position (P1). 3. Holding method according to any one of claims 1 or 2, characterized in that at least one end (11, 12; 22; 19; 2d; 2d '; 2d ”) of the blade mechanism (10, 10 ', 15 to 17, 10x) is mounted in rotation or pivoting on an axis (A'A) of the interface piece (2, 2', 2 ”, 20, 20 ') and / or on an axis ( B'B) of the lever (3, 3 ', 3 ”), parallel to the rotary shaft (4), the end (s) of the blade mechanism (14, 16, 17; 10x to 10z) which are not mounted in rotation (11, 12; 22; 19) or pivoting (2d; 2d '; 2d ”) are mounted in fixed connection (3a; 31a, 31b; 32a, 32b) with the interface part (2) and / or the lever (30; 31). 4. blade holding system of a rotary shaft (4) for implementing the method according to any one of the preceding claims, comprising a bistable pushing mechanism having two stable angular positions (P1, P2) and coupled in transverse ends respectively to an interface piece and to a lever mounted on the rotary shaft (4), this system being characterized in that this the bistable pushing mechanism (10, 10 ', 14 to 17, 10x to 10z) comprises one or more deformable blades in compression-compression (10a, 10b; 10c; 10'a, 10'b; 15a to 15d) according to pre-deformed states corresponding to both stable positions (P1, P2) , and in that each blade (10a, 10b; 10c; 10'a, 10'b; 15a to 15d) has ends or end zones (10th, 10th '; 14th, 14th'; 16th, 16th ' ; 17th, 18) fixed to the interface piece (2, 2 ', 2 ”, 20, 20') and to the lever (3, 3 ', 3”, 30, 31) by fittings ut (11, 12; 19; 22; 31a, 31b; 32a, 32b) rotatably or pivotally mounted on the interface piece (2, 2 ', 2 ”, 20, 20') and on the lever (3 , 3 ', 3 ”, 30, 31) parallel to the rotary shaft (4). 5. Holding system according to the preceding claim, in which the paired blades (10a, 10b; 10'a, 10'b; 15a to 15d) have reverse curvatures of the same absolute value when a blade (10a, 10'a, 15a, 15c) to the other (10b, 10'b, 15b, 15d) of the same couple in one or the other of the stable positions (P1, P2). 6. Holding system according to any one of claims 4 or 5 in which at least one of the fixing ends (11, 12, 19) of the blade mechanism (10, 10 ', 15, 16, 10x) is mounted on an axis of rotation (A'A, B'B), parallel to the rotary shaft (4). 7. Holding system according to the preceding claim wherein, when the fixing end piece (12) of the blade mechanism (10, 10 ', 15, 16, 10x) is mounted on an axis of rotation (B'B) of the lever (3, 3 ') parallel to the rotary shaft (4), this axis of rotation (B'B) is mounted on extensions (13) of the lever (3) extending perpendicular to the rotary shaft (4 ). 8. Holding system according to claim 4, in which, the blade mechanism (14, 10x to 10z) comprising a single blade (10c), the blade ends are fixed (14e, 14e ') on the lever (30 , 3 ”) and on the interface piece (20, 20 ', 2”) by means chosen between a rotational mounting (19, 22) on an axis (A'A) parallel to the rotary shaft (4 ), a connection (3a, 31a, 31b; 32a, 32b) on a nozzle zone (14e '; 18) and a pivoting by wedging between two faces (F3, F4; F5, F6; F'5, F' 6; F7, F8) of a dihedral (2d, 2d '). 9. Holding system according to the preceding claim, in which the faces of the dihedral for pivotally mounting the blade end have a surface of curvature chosen between plane (F3, F4; F5, F6) and convex (F'5, F'6; F7, F8). 10. Holding system according to any one of claims 4 to 7, in which the blade mechanism (10, 10 ', 15) comprising at least one pair of blades (10a, 10b; 15a to 15d), each pair ( 10a, 10b; 15a, 15b; 15c, 15d) is fixed at its transverse ends on end pieces (11, 12) mounted in rotation on axes (A'A, B'B) parallel to the rotary shaft (4) . 11. Holding system according to the preceding claim, in which at least one elastic link (6, 6a, 6b; 7) joins the blades (10a, 10b; 15a, 15b; 15c, 15d) of each pair at points or portions (1t, 1x; 1m, 1n; 1v, 1z) located at equal distance from the ends (10e, 10e ') of these blades (10a, 10b; 15a, 15b; 15c, 15d). 12. Holding system according to the preceding claim, in which the elastic link (7) consists of means chosen from at least one helical spring (6, 6a, 6b), at least one elastic band (7), and a combination spring and elastic band.