SYSTEM FOR CONTROLLING UNLOADING DOORS OF A TURBOMACHINE

Description

TECHNICAL FIELD

[0001] The invention relates to the opening and closing control of a set of discharge gates equipping a turbomachine such as a turbojet engine. PREVIOUS STATE OF THE ART

[0002] A turbofan engine has an inlet sleeve that admits air which is drawn in by a fan, before being split into a central primary flow 1 and a secondary flow 2 which surrounds the primary flow, as illustrated in the figure 1 After passing through the blower, the secondary flow is directed backwards to generate thrust.

[0003] After passing through the blower, the primary flow passes through a low-pressure compressor 3 and then a high-pressure compressor 4, before reaching a combustion chamber to be expanded in a high-pressure turbine and then in a low-pressure turbine, before being expelled generating an auxiliary thrust.

[0004] The primary flow circulates in an annular space 6, called the primary vein, delimited internally in particular by a rotor 7 and externally by an inter-vein fairing 8. The secondary flow circulates in another annular space 9, called the secondary vein, delimited internally by the inter-vein fairing 8 and externally by an external casing 11.

[0005] The inter-vein fairing 8 is traversed by discharge conduits 12, associated with discharge gates 13 usually designated by the acronym VBV (Variable Bleed Valve), which are opened in certain situations to evacuate air from the primary flow to the secondary flow, in order to avoid the establishment of a so-called pumping regime corresponding to an over-pressurization of the compressors likely to damage them.

[0006] As depicted on the figure 2These doors 13 are regularly distributed circumferentially at the level of the intervein fairing 8, so that their opening and closing requires a relatively complex actuation system. In the example of the figure 2 The actuation system comprises a rotating control ring 14 running alongside these doors 13, each door being connected to the ring by a series of connecting rods. The ring 14 is rotated by a rotary motor 16 to pivot it around the motor's axis of rotation AX so as to open and close the doors synchronously on command.

[0007] This ring has a significant thickness to ensure sufficient rigidity, and it requires precise guidance provided by pads. This combination of constraints makes such a control system bulky in both the axial and radial directions. Consequently, such a system is relatively complex to implement and, therefore, expensive.

[0008] An older alternative depicted on the figure 3 The system involves using a torsionally rigid control cable 17 running along the doors, with each door connected to this cable 17 by a set of connecting rods. The control mechanism then consists of rotating the circumferential cable on its axis to open and close the doors. In practice, the torsional rigidity of the cable remains insufficient, resulting in uneven door opening.

[0009] Documents EP 0 861 978 A1 and US 2015 / 176529 A1 describe known turbomachines.

[0010] In this context, the object of the invention is to provide an actuation system for such a set of doors which is more robust and less bulky than known systems. DESCRIPTION OF THE INVENTION

[0011] To this end, the invention relates to a control system for the discharge gates of a turbomachine, according to la claim 1, this system comprising a ring and means for connecting this ring to each discharge gate, characterized in that the ring is formed of bars connected end to end by rotational links ensuring that the pivoting of one bar on itself causes the other bars to pivot on themselves, each discharge gate being connected to a corresponding bar to open or close on pivoting of this bar.

[0012] With this arrangement, the various bars only need to be supported by reasonably sized bearings, resulting in a compact drive system. The system's operation essentially consists of driving a bar to pivot on its axis, thereby actuating all the doors, making system actuation simple.

[0013] In addition, the ring includes an alternation of control bars and transmission bars, each control bar being connected to a corresponding discharge gate.

[0014] The invention also relates to a system thus defined, in which the rotational links are Cardan joint type links.

[0015] The invention also relates to a system defined as follows, comprising a jack linked to a bar by means of an actuating lever to rotate it on itself when it extends and retracts.

[0016] The invention also relates to a system defined as follows, comprising a motor linked in rotation to a bar by means of a worm gear type linkage to rotate this bar on rotation of the motor.

[0017] The invention also relates to a system defined as follows, comprising a motor linked in rotation to a bar via a reducer to rotate it on itself.

[0018] The invention also relates to a system thus defined, comprising a door linked to a corresponding bar by an arrangement comprising a lever having one end rigidly attached to the bar, and a connecting rod having one end attached to the door and its other end attached to the lever, the ends of the connecting rod being linked to the door and to the lever by pivot joints with axes parallel to the bar.

[0019] The invention also relates to a turbomachine comprising a control system according to one of the preceding claims.

[0020] The invention also relates to a turbojet engine comprising a control system according to one of the preceding claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] There Figure 1 is a longitudinal cross-sectional view of the front part of a turbojet engine; The Figure 2 is a perspective view of a first known control system shown alone; The Figure 3 is a perspective view of a second known control system shown alone; The Figure 4 is a representation of a turbomachine equipped with the control system according to the invention, shown in a cross-sectional view; The Figure 5 is a longitudinal cross-sectional view showing a discharge gate actuated with the control system according to the invention; The Figure 6is a longitudinal cross-sectional view showing a discharge gate operated by a variant of the control system according to the irivention; The Figure 7 is a longitudinal cross-sectional view showing a discharge gate operated by another variant of the control system according to the irivention; The Figure 8 is a representation of means for pivoting a bar of the control system according to the invention. DETAILED DESCRIPTION OF SPECIFIC METHODS OF IMPLEMENTATION

[0022] On the figure 4 , a turbojet 21 comprises a central rotor 22 surrounded by an inter-flow fairing comprising an inner wall 23 surrounded by an outer wall 24. the annular space extending between the rotor 22 and the wall 23 constitutes the primary flow in which the primary flow circulates, and the space surrounding the outer wall 24 corresponds to the secondary flow in which the secondary flow circulates.

[0023] The annular space extending between walls 23 and 24 of the intervein fairing, which is called the intervein space, contains in particular discharge conduits not shown allowing the evacuation of part of the primary flow to the secondary flow.

[0024] The turbojet engine has six radial arms 25a-25f regularly spaced around the rotor's axis of rotation, which is designated by AX. Each arm 25a-25f extends radially to connect the inter-vein fairing to non-visible supports of the rotor 22.

[0025] The interveinal caring is equipped with six discharge gates, labeled 26a-26f, which, when opened, allow a portion of the primary flow to be diverted to the secondary vein. Each discharge gate is located between two radial arms and is capable of pivoting around an axis oriented orthoradially to the AX axis.

[0026] These doors 26a-26f are operated by a control system 27 comprising a ring 28 surrounding them and which is formed of twelve bars connected end to end by Cardan joints.

[0027] The bars forming the ring 28 include transmission bars 29a-29f and control bars 31a-31f, which are arranged circumferentially in alternation and are connected to each other by universal joints marked by 32. Each bar extends in an orthoradial direction with respect to the axis AX, and is able to pivot on itself around its principal axis oriented orthoradially.

[0028] The transmission rods and control rods are approximately the same length, their arrangement thus corresponding to a regular twelve-sided polygon, as seen on the figure 4 However, it is also possible to use transmission bars with a different length than the control bars.

[0029] In practice, the number of control bars corresponds to the number of doors, and the number of transmission bars is a multiple of the number of control bars, the whole assembly being sized to fit in the internal region of the inter-vein fairing.

[0030] In the example of the figure 4 Each control bar is supported by two pivot joints 33, 34 which are supported by structural elements not shown. Each transmission bar is free, that is to say, supported only by the two control bars to which it is connected by the two Cardat joints located at its ends, and it passes through a corresponding radial arm via an opening formed in the latter.

[0031] Each control bar 31a-31f carries a rotary lever 36a-36f extending perpendicularly to the bar, with its end connected to a corresponding gate by a corresponding connecting rod. These connecting rods are designated 37a-37f, and each connecting rod has one end connected to a gate by a pivot joint and its opposite end connected to the free end of a lever by another pivot joint, these pivot joints having their axes of rotation oriented orthoradially with respect to the AX axis.

[0032] The rotary levers 36a-36f extend in directions substantially parallel to the axis of rotation of the rotor, while the connecting rods 37a-37f each extend in a direction substantially radial to the axis of rotation of the rotor, as schematically represented on the figure 4 .

[0033] Thus, when the control bar 31a pivots on itself, its lever 36a pivots with it, its end being connected to the door 26a by the connecting rod 37a, so that the pivoting of the control bar 31a causes the door 26a to open or close, given that the control bar 31a pivots around an axis that is parallel to the pivot axis of the door 26a. As will be understood, the direction of rotation of the bar determines whether it is a control for opening or closing the doors.

[0034] The same applies to the other five sets comprising the other five bars operating the other five doors.

[0035] Since all the bars are linked to each other by Cardan joint type connections, the pivoting of one bar on itself causes all the bars to pivot on themselves, and thus the opening or closing of the six doors, the direction of rotation conditioning a movement of either opening or closing.

[0036] Ring 28 is set in motion by an actuator which, in the example of Figures 4 and 5 is a linear actuator 38, oriented parallel to the AX axis, with its fixed end connected to a structural part of the turbomachine, and its movable end connected to an actuating lever 39 carried by the bar 31a. As can be seen on the figure 5 , this actuation lever 39 extends radially towards the axis AX, perpendicular to the lever 36a which is also carried by this bar 31a.

[0037] In this configuration, retracting the cylinder 38 causes the control bar 31a to rotate, which opens the door 26a because it is connected to it by the lever 36a and the connecting rod 37a, and also opens all the other doors. Similarly, extending the cylinder 38 causes the door 26a and all the other doors to close.

[0038] Generally, the system includes at least one actuator such as cylinder 38, but it can also include several, each actuating a control rod, regularly distributed around the circumference of the control system. In the example of the figure 4 with six doors, one, two or three actuators can be planned.

[0039] In the example of Figures 4 and 5 The actuator used is an axially oriented linear cylinder, but other types of actuators can also be used.

[0040] Thus, in the example of the figure 6 The linear actuator 38 is positioned radially instead of extending axially as in the case of the figure 5 . More specifically, the cylinder 38 is located outside the secondary vein by being mounted on the external face of the external casing 42 surrounding this secondary vein.

[0041] This cylinder 38 is connected to the interveinal space via its movable rod, which passes radially through the secondary vein. The radially internal end of this rod is connected to the lever 36a by a fixed pivot joint. Thus, retraction of the cylinder 38 causes the control bar 31a to pivot around its orthoradial axis, which in turn opens the gate 26a to which this bar is connected by the lever 36a and the connecting rod 37a, as well as the other gates.

[0042] It is also possible to consider connecting the cylinder rod to the bar via a rack and pinion type connection.

[0043] In the example of the figure 7 , the actuator of the system consists of a rotary motor 41 which is also located outside the secondary vein by being mounted on the external face of the external casing 42.

[0044] This motor 41 is connected to the interveinal space via a rotating shaft 43 that passes radially through the secondary vein. The radially inner end of this shaft has a worm gear meshing with a toothed wheel carried by the control bar 31a. Rotating the shaft of the motor 41 around its radial axis causes the control bar 31a to pivot around its orthoradial axis. This, in turn, causes the gate 26a, to which it is connected by the lever 36a and the connecting rod 37a, to move, as well as the other gates of the system.

[0045] It is also possible, as illustrated on the figure 8 to provide a rotary motor 44 extending along the control bar 31a to drive it in rotation by means of a toothed wheel 46 directly driven by this motor and which is meshed with another toothed wheel 47 carried by the control bar 31a, so as to constitute a geared motor type assembly.

[0046] In the example of the figures, the invention is applied to tilting type doors, i.e. pivoting around an axis, but the invention can also be applied to doors having a different kinematic, such as for example doors whose opening or closing corresponds to a translational movement combined with a rotation.

Claims

1. System (27) for controlling discharge doors (26a-26f) of a turbomachine, this system comprising a ring (28) and means for connecting this ring (28) to each discharge door (26a-26f), characterised in that the ring (28) is formed by bars (29a-29f, 31a-31f) connected end to end by rotary connections (32) ensuring that the pivoting of one bar on itself brings about the pivoting of the other bars (29a-29f, 31a-31f) on themselves, each discharge door (26a-26f) being connected to a corresponding bar (31a-31f) in order to open or close when this bar pivots, comprising alternating control bars (31a-31f) and transmission bars (29a-29f), each control bar (31a-31f) being connected to a corresponding discharge door (26a-26f) in order to open and close it.

2. System according to Claim 1, wherein the rotary connections (32) are universal joints (32).

3. System according to Claim 1, comprising an actuator (38) connected to a bar (31a-31f) via an actuating lever (39) to make it pivot on itself as it extends and retracts.

4. System according to Claim 1, comprising a motor (41) rotatably connected to a bar (31a-31f) via a worm screw type connection to make this bar (31a-31f) pivot when the motor (41) rotates.

5. System according to Claim 1, comprising a motor (44) rotatably connected to a bar (31a-31f) via a reduction gear to make it pivot on itself.

6. System according to Claim 1, comprising a valve (26a-26f) connected to a corresponding bar (31a-31f) by an arrangement comprising a lever (36a-36f) with one end rigidly attached to the bar (31a-31f), and a connecting rod (37a-37f) with one end connected to the valve (26a-26f) and its other end connected to the lever (36a-36f), the ends of the connecting rod (37a-37f) being connected to the valve (26a-26f) and to the lever (36a-36f) by pivot connections with axes parallel to the bar (31a-31f).

7. Turbomachine comprising a control system according to one of the preceding claims.

8. Turbojet engine comprising a control system according to one of the preceding claims.