MECHANISM FOR DRIVE ELEMENTS FOR ADJUSTING THE ALIGNMENT OF BLADES

Description

TECHNICAL FIELD

[0001] The invention relates to a drive mechanism for adjusting the orientation of the blades of several stages of a turbomachine's stator.

[0002] The invention relates more particularly to a drive mechanism for two adjusting elements allowing the two adjusting elements to be driven simultaneously with different movement speeds of one adjusting element relative to the other. PREVIOUS STATE OF THE ART

[0003] The compressor and / or turbine of a turbomachine consists of several stages, each stage including a gas flow rectifier.

[0004] It is known to modify the orientation of the stator blades according to the operating conditions of the turbomachine, in order to optimize its efficiency.

[0005] According to a known embodiment, the change in the orientation of the stator blades is controlled by means of an actuator comprising a control shaft which cooperates with a component associated with each blade or a control box for the orientation of the blades.

[0006] Although using a single shaft to drive the blades of two stages of the stator helps to limit the number of components in the turbomachine, the size of this system is particularly large, which makes it necessary to favour this solution over large turbomachines.

[0007] The use of a control box is adaptable to any size turbomachine. However, this solution involves a large number of components, which reduces the system's accuracy due to the cumulative play between the numerous components and their respective deformations. Document EP 2 626 521 A1 concerns an actuation mechanism for variable-speed blades in axial-flow gas turbine engines. The blades are variable in that they rotate around their main axis, so the fluid flow distribution angle at a rotor stage of a compressor or other turbine can be modified to improve engine performance.

[0008] The invention aims to provide a drive mechanism for the blade orientation adjustment means which is both compact and comprises a reduced number of parts. DESCRIPTION OF THE INVENTION

[0009] The invention proposes a drive mechanism as described in claim 1.

[0010] Such a drive mechanism makes it possible to concentrate the functions of drive and variability of transmission ratios into a reduced number of components, thus reducing the mass of the drive mechanism.

[0011] According to the invention, the transmission ratio of the gear stage associated with the second adjusting member is variable depending on the angular position of the drive wheel in the turbomachine.

[0012] Preferably, the gear stage associated with the second adjusting member comprises a first toothed wheel that meshes with the driving wheel, a second toothed wheel that meshes with a toothed portion of the second adjusting member, and means for coupling the two wheels together to vary the transmission ratio of the gear stage.

[0013] Preferably, the gear stage associated with the second adjusting element is designed to vary the transmission ratio of the gear stage in a non-linear manner.

[0014] Preferably, the axes of rotation of the two wheels of the gear stage associated with the second adjusting member are parallel and offset from each other.

[0015] Preferably, one of the two wheels has a groove and the other wheel has a finger projecting axially relative to said other wheel, the finger being received in the groove and being able to cooperate with the groove to transmit a torque from the first wheel to the second wheel.

[0016] Preferably, the groove is formed in the first gear and the finger is carried by the second gear.

[0017] Preferably, the gear stage associated with the first adjusting member includes a third toothed wheel which meshes with the driving wheel and a complementary toothed portion of the first adjusting member.

[0018] The invention also relates to an aircraft turbomachine comprising two stages of a stator whose blade orientation can be modified, characterized in that each stage of a stator comprises an adjustment device for the orientation of the blades of said stage of a stator, the two adjustment devices being rotationally movable in the turbomachine around the main axis of the turbomachine and being driven in rotation by a drive mechanism according to the invention.

[0019] Preferably, each adjusting member comprises a first toothed portion associated with the associated gear stage and a second toothed portion which meshes with a toothed wheel carried by each blade of the associated rectifier stage. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Other features and advantages of the invention will become apparent from the following detailed description, for the understanding of which reference will be made to the attached figures, among which the single figure is a schematic representation of a drive mechanism made according to the invention. DETAILED DESCRIPTION OF SPECIFIC METHODS OF IMPLEMENTATION

[0021] Figure 10 shows a mechanism for driving a blade orientation control element 12 of the blades 14 of a first stage 16 of a turbomachine straightener and a blade orientation control element 18 of the blades 20 of a second stage 22 of a turbomachine straightener.

[0022] The blade orientation control devices 12, 18 for the 14, 20 blades each consist of a ring associated with each stator stage 16, 22, which is rotatable within the turbomachine about the main axis of the turbomachine (not shown). An axial end 12a, 18a of each ring 12, 18 has a toothed portion that meshes with a gear carried by each blade 14, 20.

[0023] Thus, the rotation of a ring 12, 18 in the turbomachine causes the simultaneous rotation of all the blades 14, 20 of the stage 16, 22 of the rectifier associated with it.

[0024] When the operating conditions of the turbomachine change, the orientation of the blades 14, 20 of the two stages 16, 22 of the stator must be modified simultaneously to optimize the turbomachine's performance. Therefore, the blades 14 of the first stage 16 of the stator pivot at a different angle relative to the pivot angle of the blades 20 of the second stage 22 of the stator.

[0025] The mechanism 10 for driving the adjusting rings 12, 18 is designed to simultaneously drive the two rings 12, 18 in motion and so that the amplitude of displacement of the first ring 12, associated with the first stage 16 of rectifier is different from the amplitude of displacement of the second ring 18 which is associated with the second stage 22 of rectifier.

[0026] For the simultaneous driving of the two rings 12, 18, the drive mechanism 10 includes a single drive wheel 24 which is coupled to the two rings 12, 18 via two stages of gears 26, 28.

[0027] The first stage of gears 26 is associated with the first ring 12 of the first stage 16 of rectifier and it has a single toothed wheel 30 which is meshed with the driving wheel 24 and with the first ring 12.

[0028] The second gear stage 28 is associated with the second ring 18 and it comprises a first gear 32 which meshes with the drive wheel 24 and a second gear 34 which meshes with the second ring 18. The two gears of the second gear stage 28 cooperate with each other to transmit the drive forces from the first gear 32 to the second gear 34.

[0029] The second axial end 12b, 18b of each ring 12, 18 has for this purpose a toothed portion 44 which cooperates with the wheel 30, 34 of the first stage of gears 26 or of the second stage of gears 28 which is associated with it.

[0030] The first wheel 32 and the second wheel 34 are coupled to each other to provide a transmission ratio different from the transmission ratio provided by the toothed wheel 30 of the first stage of gears 26.

[0031] Here, the transmission ratio provided by the toothed wheel 30 of the first stage of gears 26 is linear and is constant regardless of the angular position of the driving wheel 24. The transmission ratio provided by the second stage of gears 28 is therefore non-linear.

[0032] According to a preferred embodiment, the transmission ratio of the second stage of gears 28 is variable and it varies according to the angular position of the driving wheel 24, and therefore of the first wheel 32.

[0033] The first wheel 32 and the second wheel 34 are arranged parallel to each other, and their respective axes of rotation 36, 38 are parallel and radially offset from each other. The two wheels 32, 34 are coupled by means allowing the transmission ratio of the second gear stage 28 to be varied.

[0034] These coupling means consist here of a set of groove 40 and follower finger 42, each of which is respectively carried by one or the other of the first or second wheel 32, 34.

[0035] Here, the groove 40 is formed in the first wheel 32 and it has a main radial orientation with respect to the axis 36 of rotation of the first wheel 32. The finger 42 is carried by the second wheel 34, projecting axially with respect to a radial face 34a of the second wheel 34 opposite the first wheel 32 and it is received in the groove 40.

[0036] Since the respective axes of rotation 36, 38 of the two wheels 32, 34 are offset from each other, when the first wheel 32 rotates, the finger 42 moves in the groove 40, thus changing the distance between the finger 42 and the axis of rotation 36 of the first wheel 32. The transmission ratio is then changed.

[0037] It will be understood that the invention is not limited to this single configuration of the groove 40 and the finger 42 and that the groove 40 may not be straight, to obtain a given law defining the transmission ratio of the second stage of gears 28.

[0038] In addition, according to the embodiment shown, the axis of rotation of the drive wheel 24 is globally perpendicular to the axes of rotation 36, 38 of the wheels 30, 32, 34 of the gear stages 26, 28. According to an alternative embodiment, the axes of rotation of the different wheels 24, 30, 32, 34 are parallel.

[0039] The turbomachine (not shown) comprising the rectifier stages 16, 22 and the drive mechanism 10 defined above is then of simpler structure.

Claims

1. A drive mechanism (10) for driving a first adjustment member (12) for adjusting the orientation of the blades (14) of a first turbomachine rectifier stage (16) and a second adjustment member (18) for adjusting the orientation of the blades (20) of a second turbomachine rectifier stage (22), which includes means for simultaneously moving the two adjustment members (12, 18) in the turbomachine, wherein the drive mechanism includes a single drive wheel (24) that simultaneously drives the first adjustment member (12) and the second adjustment member (18) and includes two gear stages (26, 28) that are arranged between the drive wheel (24) and one or the other of the first adjustment member (12) and the second adjustment member (18) and that have different transmission ratios, characterized in that the transmission ratio of the gear stage (28) associated with the second adjustment member (18) is variable according to the angular position of the drive wheel (24) in the turbomachine.

2. The drive mechanism (10) according to the preceding claim, characterized in that the gear stage (28) associated with the second adjustment member (18) includes a first toothed wheel (32) that is engaged with the drive wheel (24), a second toothed wheel (34) that is engaged with a toothed portion (44) of the second adjustment member (18) and the coupling means (40, 42) for coupling the two wheels (32, 34) with each other to vary the transmission ratio of the gear stage (28).

3. The drive mechanism (10) according to the preceding claim, characterized in that the gear stage (28) associated with the second adjustment member (18) is produced to vary the transmission ratio of the gear stage (28) in a non-linear manner.

4. The drive mechanism (10) according to the preceding claim, characterized in that the axes of rotation (36, 38) of the two wheels (32, 34) of the gear stage (28) associated with the second adjustment member (18) are parallel and offset from one another.

5. The drive mechanism (10) according to the preceding claim, characterized in that one (32) of the two wheels includes a groove (40) and the other wheel (34) includes a pin (42) projecting axially with respect to said other wheel (34), the pin (42) being received in the groove (40) and being capable of cooperating with the groove (40) to transmit a torque from the first wheel (32) to the second wheel (34).

6. The drive mechanism (10) according to the preceding claim, characterized in that the groove (40) is formed in the first gear wheel (32) and the pin (42) is borne by the second gear wheel (34).

7. The drive mechanism (10) according to any one of the preceding claims, characterized in that the gear stage (26) associated with the first adjustment member (12) includes a third toothed wheel (30) that is engaged with the drive wheel (24) and a complementary toothed portion (44) of the first adjustment member (12).

8. An aircraft turbomachine comprising two rectifier stages (16, 22) wherein the orientation of the blades (14, 20) can be modified, characterized in that each rectifier stage includes an adjustment member (12, 18) for adjusting the orientation of the blades (14, 20) of said rectifier stage (16, 22), the two adjustment members (12, 18) being movable in rotation in the turbomachine about the main axis of the turbomachine and being driven in rotation by a drive mechanism (10) according to any one of the preceding claims.

9. The turbomachine according to the preceding claim, characterized in that each adjustment member (12, 18) includes a first toothed potion (44) associated with the associated gear stage (26, 28) and a second toothed portion that meshes with a toothed wheel borne by each blade (14, 20) of the associated rectifier stage (16, 22).