A GTF engine gearbox with adjustable support stiffness

Abstract

The present invention discloses a GTF engine gearbox with adjustable support stiffness, belonging to the field of aircraft power technology; it includes a box body, an input shaft and an output shaft; the input shaft and the output shaft respectively penetrate the upper box cover and the lower box cover, and are driven by a gear mechanism in the box body; the gear mechanism includes a sun gear, a planetary gear assembly, an inner gear ring and an inner gear ring mounting plate, the sun gear is coaxially mounted on the inner end of the input shaft, and the inner gear ring is coaxially mounted on the inner end face of the output shaft through the inner gear ring mounting plate 8 and is coaxial with the sun gear 6; a plurality of planetary gear assembly devices are circumferentially arranged between the sun gear and the inner gear ring, and mesh with the sun gear and the inner gear ring respectively; a stiffness adjustment device is arranged on the lower box cover. The present invention adopts a segmented planetary gear, which solves the problem of uneven force on the spline of the segmented sun gear caused by manufacturing and installation errors; the stiffness adjustment device can adjust the support stiffness of the herringbone inner gear ring, ensuring that the inner gear ring always maintains the best support stiffness at different speeds.

Description

Technical Field

[0001] The invention belongs to the technical field of aircraft power, and in particular relates to a GTF engine gearbox with adjustable support stiffness. Background Art

[0002] Reducing fuel consumption, reducing emissions, and reducing vibration and noise are the main development directions of the next generation of aircraft engines.

[0003] At present, in high-thrust high-bypass turbofan engines, the fan is mostly driven directly by the low-pressure turbine. This design has an inherent disadvantage, that is, the boost compressor and the low-pressure turbine are not working at their optimal speed. Compared with the traditional twin-rotor turbofan engine, the core engine of the gear-driven fan (GTF) engine has no fundamental changes, but only adds a gearbox, so that the fan of the engine works independently of the low-pressure compressor and turbine, so that the fuel combustion efficiency is higher, the fan speed is lower, and it has the advantages of low fuel consumption, low noise, low emissions and low maintenance costs. In view of the technical performance characteristics and performance advantages of the gear-driven fan (GTF) engine, the gear-driven fan (GTF) engine has an attractive market application development prospect in regional aircraft and single-aisle mainline aircraft engines.

[0004] my country's research on GTF aircraft engines is still in the pre-research stage. At present, relevant scientific research and exploration work is being carried out, and some results have been achieved. For example, Chinese patent CN201410309501.8 discloses a new type of GTF aircraft engine fan main reducer, which adopts a multi-star gear herringbone gear transmission to improve the load-bearing capacity and reduce vibration noise. In order to facilitate assembly, a split internal gear ring is adopted, but the herringbone internal gear ring is spliced ​​with two helical gear internal gear rings, which cannot guarantee the assembly accuracy when the two tooth segment bevels are combined and connected, and the connection and positioning functions of the bolts are limited. In order to overcome the above problems, Chinese patent CN201610594040.2 proposes a gear drive fan (GTF) engine gear transmission device, which adopts a segmented herringbone sun gear. Although it solves the problem that the segmented herringbone gear ring is difficult to assemble, due to the existence of manufacturing and installation errors, the segmented sun gear will cause a certain misalignment on both sides of the sun gear, so that there is a torque at the shaft end of the input shaft where the sun gear is installed, resulting in uneven force on the spline on the input shaft, affecting the service life of the spline.

[0005] At the same time, since the speed of the GTF engine is not always constant during operation, it needs to adjust different speeds according to different environments, and the support stiffness that minimizes the vibration noise of the GTF engine gearbox is different at different speeds. The existing GTF engine gearbox cannot change the gear support stiffness during design, and cannot make the GTF engine gearbox always work in the optimal stiffness state, which affects the stability of the GTF engine gearbox transmission. Summary of the invention

[0006] Technical issues to be solved:

[0007] In order to avoid the shortcomings of the prior art, the present invention proposes a GTF engine gearbox with adjustable support stiffness, which adopts a segmented planetary gear, thereby avoiding the problem of low assembly precision and difficulty of the segmented herringbone internal gear ring, and solving the problem of uneven spline force on the segmented sun gear caused by manufacturing and installation errors; a stiffness adjustment device can adjust the support stiffness of the herringbone internal gear ring to ensure that the internal gear ring always maintains the optimal support stiffness at different rotation speeds, so that the vibration and noise of the gearbox are kept at the lowest state and the transmission is smoother; the elastic shaft with symmetrical grooves can realize elastic support of the planetary gear, which is beneficial to the load balance of the GTF gearbox.

[0008] The technical scheme of the present invention is: a GTF engine gearbox with adjustable support stiffness, comprising a box body 1, an input shaft 5 and an output shaft 12, wherein the two ends of the box body 1 are respectively encapsulated with an upper box cover 2 and a lower box cover 10; the input shaft 5 and the output shaft 12 respectively penetrate the upper box cover 2 and the lower box cover 10, and are transmitted through a gear mechanism in the box body 1; the gear mechanism comprises a sun gear 6, a star gear assembly device, an inner gear ring 7 and an inner gear ring mounting plate 8, the sun gear 6 is coaxially fixedly mounted on the inner end of the input shaft 5, the inner gear ring 7 is coaxially mounted on the inner end face of the output shaft 12 through the inner gear ring mounting plate 8, and is coaxial with the sun gear 6; a plurality of star gear assembly devices are circumferentially arranged between the sun gear 6 and the inner gear ring 7, and are respectively meshed with the sun gear 6 and the inner gear ring 7;

[0009] The lower box cover 10 is provided with a stiffness adjusting device, which uses a lead screw transmission as a power to adjust the supporting length of the inner gear ring 7 to achieve the adjustment of the supporting stiffness.

[0010] A further technical solution of the present invention is: the stiffness adjustment device comprises a guide rod 20, a ball 21, a slide bar 22, a second spring 23, a lead screw 24, a lead screw nut 25, a push plate 26, a second pressure plate 27, a drive motor 28, a first pressure plate 29, a slide block 30 and a first spring 31;

[0011] The inner end of the output shaft 12 is a disc structure, and an annular groove is opened along the circumferential direction on the end surface close to the lower box cover 10, and multiple guide rods 20 are evenly distributed on the bottom surface of the annular groove of the output shaft 12 along the circumferential direction; the first spring 31 and the slider 30 are coaxially sleeved on the guide rod 20 in sequence, and the inner and outer ring surfaces of the annular groove of the output shaft 12 are opened along the circumferential direction with an axial first sliding groove, which corresponds to the guide rod 20 one by one, and serves as a sliding track for the slider 30;

[0012] The drive motor 28 is fixed to the outer end surface of the lower box cover 10, and its output shaft is coaxially connected with the lead screw 24. The lead screw 24 passes through one end of the push plate 26 and is equipped with a lead screw nut 25. The push plate 26 is coaxially sleeved with the outer end neck of the lower box cover 10.

[0013] The end surface of the lower case cover 10 is uniformly provided with a plurality of through holes along the circumferential direction, serving as second slide grooves, and a plurality of slide rods 22 correspond to each other and respectively penetrate through the plurality of second slide grooves, one end of which is fixed to the inner end surface of the push plate 26 through the second pressure plate 27, and the other end is fixed to one end surface of the first pressure plate 29; the first pressure plate 29 is located between the lower case cover 10 and the inner end of the output shaft 12, and is respectively connected to the plurality of slide blocks 30 through a plurality of ball bearings 21; a second spring 23 is sleeved on the slide rod 22 between the lower case cover 10 and the second pressure plate 27;

[0014] The lead screw 24 is driven to rotate by the driving motor 28, and the rotational motion is converted into the axial linear motion of the push plate 26, and then the displacement is transmitted through the slide rod 22, so as to change the distance between the bottom of the slider 30 and the bottom of the annular groove of the output shaft 12, so as to adjust the support stiffness.

[0015] A further technical solution of the present invention is: a plurality of sleeves 9 are evenly distributed along the circumferential direction at the outer edge of the inner end of the output shaft 12, and the inner gear ring mounting plate 8 is fixedly connected to the inner end of the output shaft 12 by bolts and sleeves 9 arranged along the circumferential direction.

[0016] A further technical solution of the present invention is: the star wheel assembly device comprises a star wheel shaft 3, a first star wheel 14, an elastic shaft 15, a second star wheel 16, an angular contact ball bearing 17 and a bearing sleeve 18; one end of the star wheel shaft 3 is fixed to the inner end of the upper box cover 2, and the other end is sleeved with an angular contact ball bearing 17 and a bearing sleeve 18, and the bearing sleeve 18 is arranged between the two angular contact ball bearings 17; the first star wheel 14 and the second star wheel 16 are coaxially installed on the two angular contact ball bearings 17 in parallel through the elastic shaft 15, and can rotate relative to the star wheel shaft 3;

[0017] The elastic shaft 15 is a sleeve structure, and annular protrusions are circumferentially arranged in the middle of the inner circumference and the outer circumference. The annular protrusion on the inner circumference is located between two angular contact ball bearings 17 to axially position the elastic shaft 15; the first star wheel 14 and the second star wheel 16 are respectively mounted on both sides of the annular protrusion on the outer circumference; annular grooves are respectively opened on the two end surfaces of the elastic shaft 15 along the circumferential direction.

[0018] A further technical solution of the present invention is that the bottom of the annular grooves at both ends of the elastic shaft 15 is flush with the side walls of the annular protrusions, and the inner groove wall of the annular groove close to the inner circumference of the elastic shaft 15 is arc-shaped.

[0019] A further technical solution of the present invention is: the sun gear 6 is an integral herringbone external gear, the inner ring gear 7 is an integral herringbone internal gear, the helix angle rotation direction of the first star gear 14 and the second star gear 16 are opposite; the helix angle rotation direction of the sun gear 6 is determined according to the rotation direction of the gear under normal working conditions.

[0020] A further technical solution of the present invention is: limit rings 19 are respectively installed at both ends of the elastic shaft 15 to limit the circumferential displacement of the first star wheel 14 and the second star wheel 16; gaskets are provided between the two limit rings 19 and the elastic shaft 15; the gaskets are made of alloy steel and have an anti-slip layer on their surface.

[0021] A further technical solution of the present invention is: the input shaft 5 is rotatably connected to the upper case cover 2 via a deep groove ball bearing, and an input shaft end cover 4 is fixed to the outer end of the upper case cover 2 for positioning the input shaft 5 .

[0022] A further technical solution of the present invention is that the output shaft 12 is rotatably connected to the lower case cover 10 via a spherical roller bearing, and an output shaft end cover 13 is fixed to the outer end of the lower case cover 10 for positioning the output shaft 12 .

[0023] A further technical solution of the present invention is that lubricating grease is applied between the push plate 26 and the second slide groove.

[0024] Beneficial Effects

[0025] The beneficial effects of the present invention are:

[0026] 1. The use of segmented planetary gears avoids the problem of low assembly precision and difficulty of segmented herringbone internal gear rings, and solves the problem of uneven spline force caused by manufacturing and installation errors of segmented sun gears;

[0027] 2. The stiffness adjustment device can adjust the support stiffness of the herringbone internal gear ring to ensure that the internal gear ring always maintains the best support stiffness at different speeds, so that the vibration and noise of the gear box are kept to the lowest state and the transmission is more stable;

[0028] 3. Deep annular grooves are symmetrically provided on the end faces of both ends of the elastic shaft 15, and the inner wall of the groove close to the axis is arc-shaped. This structure increases the elasticity of the elastic shaft 15, so that the first star wheel 14 and the second star wheel 16 on the shaft can automatically deflect when the force is unbalanced, so as to make the load distribution more uniform, realize the elastic support of the planetary gear, and facilitate the load balancing of the GTF gearbox. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a schematic diagram of the overall structure of a GTF engine gearbox with adjustable support stiffness proposed by the present invention;

[0030] Figure 2 This is an enlarged schematic diagram of the structure at A;

[0031] Figure 3 This is an enlarged schematic diagram of the structure at B;

[0032] Figure 4 It is a schematic diagram of the output shaft structure;

[0033] Figure 5 It is a schematic diagram of the structure of the inner gear ring mounting plate;

[0034] Figure 6 It is a schematic diagram of the slider structure;

[0035] Figure 7 is a schematic diagram of the elastic shaft structure;

[0036] Figure 8 It is a schematic diagram of the push plate structure.

[0037] Explanation of the reference numerals: 1 housing, 2 upper housing cover, 3 star gear shaft, 4 input shaft end cover, 5 input shaft, 6 sun gear, 7 inner gear ring, 8 inner gear ring mounting plate, 9 sleeve, 10 lower housing cover, 11 spherical roller bearing, 12 output shaft, 13 output shaft end cover, 14 first star gear, 15 elastic shaft, 16 second star gear, 17 angular contact ball bearing, 18 bearing sleeve, 19 limiting ring, 20 guide rod, 21 ball, 22 sliding rod, 23 second spring, 24 lead screw, 25 lead screw nut, 26 push plate, 27 second pressure plate, 28 drive motor, 29 first pressure plate, 30 slider, 31 first spring. DETAILED DESCRIPTION

[0038] The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, but should not be construed as limiting the present invention.

[0039] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0040] Reference Figure 1As shown, the present invention provides a GTF engine gearbox with adjustable support stiffness, comprising a housing 1, an input shaft 5 and an output shaft 12, wherein an upper housing cover 2 and a lower housing cover 10 are respectively encapsulated at both ends of the housing 1; the input shaft 5 and the output shaft 12 respectively penetrate the upper housing cover 2 and the lower housing cover 10, and are driven by a gear mechanism in the housing 1; the gear mechanism comprises a sun gear 6, a star gear assembly device, an inner gear ring 7 and an inner gear ring mounting plate 8, wherein the sun gear 6 is coaxially fixedly mounted on the inner end of the input shaft 5, and the inner gear ring 7 is coaxially mounted on the inner end face of the output shaft 12 through the inner gear ring mounting plate 8 and is coaxial with the sun gear 6; a plurality of star gear assembly devices are circumferentially arranged between the sun gear 6 and the inner gear ring 7, and are respectively meshed with the sun gear 6 and the inner gear ring 7;

[0041] The lower box cover 10 is provided with a stiffness adjusting device, which uses a lead screw transmission as a power to adjust the supporting length of the inner gear ring 7 to achieve the adjustment of the supporting stiffness.

[0042] Example:

[0043] Reference Figure 1-8 The present invention discloses a GTF engine gearbox with adjustable support stiffness, comprising a box body 1, wherein the box body 1 and the upper box cover 2 are generally fixed by screws, an input shaft 5 passes through the upper box cover 2 and is rotatably connected to the upper box cover 2 by a deep groove ball bearing, an input shaft end cover 4 is fixedly connected to the outer surface of the port of the upper box cover 2 by screws, the input shaft end cover 4 is sleeved on the input shaft 5 to position the input shaft 5, a plurality of star wheel shafts 3 are uniformly penetrated along the circumferential direction on the inner end surface of the upper box cover 2, the star wheel shafts 3 are fixedly connected to the upper box cover 2 by screws, a first star wheel 14 and a second star wheel 16 are provided at the lower end of each star wheel shaft 3, and the first star wheel 14, the second star wheel 16 and the star wheel shaft 3 constitute a star wheel assembly device.

[0044] Reference Figure 2 As shown, the star wheel assembly device also includes two angular contact ball bearings 17 sleeved on the lower end of the star wheel shaft 3, a bearing sleeve 18 is provided in the middle of the two angular contact ball bearings 17, two third elastic retaining rings are provided on the circumferential surface of the star wheel shaft 3, the two angular contact ball bearings 17 are located between the two elastic retaining rings, the two elastic retaining rings and the bearing sleeve 18 jointly limit the two angular contact ball bearings 17, and the elastic shaft 15 is sleeved on the outer rings of the two angular contact ball bearings 17; refer to Figure 7As shown, deep annular grooves are symmetrically provided on the end faces of both ends of the elastic shaft 15, and the inner wall of the groove close to the axis is arc-shaped. The grooved structure on the end face increases the elasticity of the elastic shaft 15, so that the first star wheel 14 and the second star wheel 16 on the shaft can automatically deflect when the force is unbalanced, so as to make the load distribution more uniform; a first annular boss is provided on the inner wall of the elastic shaft 15, and the elastic shaft 15 is restricted between the two angular contact ball bearings 17 by the first annular boss, and a second annular boss is provided on the outer wall of the elastic shaft 15, and the upper side of the second annular boss of the elastic shaft 15 A first star wheel 14 is provided on the outer wall, and a second star wheel 16 is provided on the outer wall at the lower side of the second annular boss of the elastic shaft 15; the side walls on both sides of the elastic shaft 15 are fixedly connected with limit rings 19 by screws, and gaskets are provided between the two limit rings 19 and the elastic shaft 15. The gaskets are made of alloy steel, and the surface of the gaskets is provided with an anti-slip layer. The function of the gaskets is to better press the first star wheel 14 and the second star wheel 16 on the elastic shaft 15 to prevent them from rotating relative to the elastic shaft 15, so that the first star wheel 14, the second star wheel 16 and the elastic shaft 15 constitute a combined herringbone gear.

[0045] A sun gear 6 is provided at the lower end of the input shaft 5, and the input shaft 5 is connected to the internal spline of the sun gear 6 through an external spline. A first elastic retaining ring is provided at the lower end of the input shaft 5, and the first elastic retaining ring limits the sun gear 6. Each of the first star gear 14 and the second star gear 16 is meshed with the sun gear 6. The sun gear 6 is an integral herringbone external gear. The helix angle rotation direction of the first star gear 14 and the second star gear 16 is opposite. The helix angle rotation direction of the sun gear 6 is determined according to the rotation direction of the gear under normal working conditions, and the directions of the axial forces on both sides of the sun gear should be opposite. The lower side of the housing 1 is fixedly connected with a lower case cover 10 by screws, and the output shaft 12 passes through the lower case cover 10 and is rotatably connected to the lower case cover 10 through a spherical roller bearing 11; the outer side of the port of the lower case cover 10 is fixedly connected with an output shaft end cover 13 by screws, and the output shaft end cover 13 passes through the output shaft 12 to position it, and a stiffness adjustment device is provided between the output shaft 12 and the lower case cover 10.

[0046] Reference Figure 3 As shown, the stiffness adjustment device includes a driving motor 28 fixedly connected to the outer end surface of the lower box cover 10 by screws, an annular groove is opened on the end surface of the output shaft 12 along the circumferential direction, and a plurality of guide rods 20 are evenly fixedly connected to the inner bottom of the U-shaped annular groove. The guide rods 20 are fixed to the inner bottom of the U-shaped groove by welding, and first sliding grooves are opened on the inner walls of both sides of the U-shaped groove near each guide rod 20. The inner walls of the two first sliding grooves located near the same guide rod 20 are slidably connected to the sliders 30 (as shown in FIG. Figure 6As shown in the figure, the guide rod 20 penetrates the slider 30 downward, the guide rod 20 is slidably connected to the slider 30, the portion of the guide rod 20 between the slider 30 and the U-shaped groove is sleeved with a first spring 31, and the lower end of the slider 30 is rollingly connected with a ball 21; the output shaft of the driving motor 28 is fixedly connected with a lead screw 24, a plurality of second slide grooves are evenly opened on the side wall of the lower box cover 10, a plurality of second slide grooves are slidably connected with a push plate 26 in the plurality of second slide grooves, grease is applied between the push plate 26 and the second slide grooves, a plurality of slide rods 22 are evenly penetrated on the side wall of the lower box cover 10, and each slide rod 22 is connected to the lower box cover 10 Sliding connection, the upper end of each slide bar 22 is commonly fixedly connected with a first pressure plate 29, the first pressure plate 29 and the ball 21 are pressed against each other by the elastic force of the spring to prevent the ball 21 from falling, and at the same time, the ball 21 has the function of reducing friction, the lower end of each slide bar 22 is commonly fixedly connected with a second pressure plate 27, the slide bar 22 and the second pressure plate 27 are welded and fixed, and the part of each slide bar 22 located between the second pressure plate 27 and the lower box cover 10 is sleeved with a second spring 23, the first spring 31 and the second spring 23 are both compression springs, and the push plate 26 is fixedly connected with the second pressure plate 27 by welding; refer to Figure 8 As shown, a through hole is opened on the end surface of the push plate 26, and a lead screw nut 25 is fixedly connected to the side wall of the push plate 26 located at the through hole by screws. The lead screw 24 passes downward through the through hole and cooperates with the lead screw nut 25.

[0047] Reference Figure 4 , 5 As shown, a plurality of sleeves 9 are evenly provided at the outer edge of the inner end of the output shaft 12, and an inner gear ring mounting plate 8 is commonly provided at one end of the plurality of sleeves 9 away from the output shaft 12. The inner gear ring mounting plate 8, the sleeve 9 and the output shaft 12 are fixedly connected by bolts. An inner gear ring 7 is provided on the inner wall of the inner gear ring mounting plate 8. The inner gear ring 7 is an integral herringbone inner gear ring. The inner gear ring 7 is connected to the inner gear ring mounting plate 8 through an external spline. Second elastic retaining rings are provided on both sides of the inner wall of the inner gear ring mounting plate 8. The second elastic retaining ring positions the inner gear ring 7. The inner gear ring 7 is meshed with each of the first star wheel 14 and the second star wheel 16.

[0048] During operation, the power of the low-pressure turbine is transmitted from the output shaft 5 to the sun gear 6, and the sun gear 6 transmits the power to the first star gear 14 and the second star gear 16. Since the first star gear 14 and the second star gear 16 are pressed against the elastic shaft 15, the first star gear 14 and the second star gear 16 rotate on the star gear shaft 3 together with the elastic shaft 15. The number of the star gear shafts 3 is greater than or equal to two, and each star gear shaft 3 contains the first star gear 14, the second star gear 16, the elastic shaft 15 and other structures. The formed combined star gears are respectively meshed with the sun gear 6 and the inner gear ring 7 to transmit power.

[0049] When the supporting stiffness of the inner gear ring needs to be adjusted, the driving motor 28 is controlled to work. The control of the motor is the existing technology. The driving motor 28 drives the screw 24 to rotate. The screw 24 converts the rotational motion into linear motion through the screw nut 25 matched with it, so that the push plate 26 drives the second pressure plate 27 to move. The second pressure plate 27 drives the slide bar 22 connected to it to slide in the slideway opened on the side wall of the lower box cover 10, driving the first pressure plate 29 inside the box body 1 to move. The first pressure plate 29 pushes the slider 30 to slide in the U-shaped groove to change the distance between the outer support position of the U-shaped groove and the end of the slider 30 away from the ball 21. Changing this distance is equivalent to changing the support length of the cantilever beam, thereby achieving the purpose of changing the support stiffness.

[0050] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and intent of the present invention.

Claims

1. A GTF engine gearbox with adjustable support stiffness, comprising a housing (1), an input shaft (5) and an output shaft (12), wherein an upper housing cover (2) and a lower housing cover (10) are respectively encapsulated at two ends of the housing (1); the input shaft (5) and the output shaft (12) respectively penetrate the upper housing cover (2) and the lower housing cover (10), and are driven by a gear mechanism in the housing (1); the characteristics are: The gear mechanism comprises a sun gear (6), a star gear assembly, an inner gear ring (7) and an inner gear ring mounting plate (8); the sun gear (6) is coaxially fixedly mounted on the inner end of the input shaft (5); the inner gear ring (7) is coaxially mounted on the inner end face of the output shaft (12) through the inner gear ring mounting plate (8) and is coaxial with the sun gear (6); a plurality of star gear assembly devices are circumferentially arranged between the sun gear (6) and the inner gear ring (7), and are respectively meshed with the sun gear (6) and the inner gear ring (7); The lower box cover (10) is provided with a stiffness adjustment device, which uses a lead screw transmission as a power source to adjust the support length of the inner gear ring (7) to achieve adjustment of the support stiffness; The stiffness adjustment device comprises a guide rod (20), a ball bearing (21), a slide rod (22), a second spring (23), a lead screw (24), a lead screw nut (25), a push plate (26), a second pressure plate (27), a drive motor (28), a first pressure plate (29), a slide block (30) and a first spring (31); The inner end of the output shaft (12) is a disc structure, and an annular groove is opened along the circumferential direction on the end surface of the output shaft (12) close to the lower box cover (10), and a plurality of guide rods (20) are evenly distributed along the circumferential direction on the bottom surface of the annular groove of the output shaft (12); the first spring (31) and the slider (30) are coaxially sleeved on the guide rod (20) in sequence, and an axial first sliding groove is opened along the circumferential direction on the inner and outer ring surfaces of the annular groove of the output shaft (12), which corresponds to the guide rod (20) one by one and serves as a sliding track for the slider (30); The drive motor (28) is fixed to the outer end surface of the lower box cover (10), and its output shaft is coaxially connected to the lead screw (24). One end of the lead screw (24) passes through the push plate (26) and is equipped with a lead screw nut (25). The push plate (26) is coaxially sleeved on the outer end neck of the lower box cover (10); The end surface of the lower box cover (10) is uniformly provided with a plurality of through holes along the circumferential direction, serving as second slide grooves, and a plurality of slide rods (22) correspond to each other and respectively penetrate the plurality of second slide grooves, one end of which is fixed to the inner end surface of the push plate (26) through a second pressure plate (27), and the other end is fixed to a side end surface of the first pressure plate (29); the first pressure plate (29) is located between the lower box cover (10) and the inner end of the output shaft (12), and is slidably connected to the plurality of slide blocks (30) through a plurality of ball bearings (21); a second spring (23) is sleeved on the slide rod (22) between the lower box cover (10) and the second pressure plate (27); The lead screw (24) is driven to rotate by a driving motor (28), thereby converting the rotary motion into the axial linear motion of the push plate (26), and then transmitting the displacement through the slide rod (22), thereby changing the distance between the bottom of the slide block (30) and the bottom of the annular groove of the output shaft (12), thereby achieving the adjustment of the support stiffness.

2. The GTF engine gearbox with adjustable support stiffness according to claim 1, characterized in that: A plurality of sleeves (9) are evenly distributed along the circumferential direction at the outer edge of the inner end of the output shaft (12), and the inner gear ring mounting plate (8) is fixedly connected to the inner end of the output shaft (12) via bolts and sleeves (9) arranged along the circumferential direction.

3. The GTF engine gearbox with adjustable support stiffness according to claim 1, characterized in that: Lubricating grease is applied between the push plate (26) and the second slide groove.

4. The GTF engine gearbox with adjustable support stiffness according to claim 1, characterized in that: The star wheel assembly device comprises a star wheel shaft (3), a first star wheel (14), an elastic shaft (15), a second star wheel (16), an angular contact ball bearing (17) and a bearing sleeve (18); one end of the star wheel shaft (3) is fixed to the inner end of the upper box cover (2), and the other end is sleeved with an angular contact ball bearing (17) and a bearing sleeve (18), and the bearing sleeve (18) is arranged between two angular contact ball bearings (17); the first star wheel (14) and the second star wheel (16) are coaxially mounted on the two angular contact ball bearings (17) in parallel via the elastic shaft (15), and can rotate relative to the star wheel shaft (3); The elastic shaft (15) is a sleeve structure, and an annular protrusion is provided in the middle of the inner circumferential surface and the outer circumferential surface along the circumferential direction. The annular protrusion on the inner circumferential surface is located between two angular contact ball bearings (17) to axially position the elastic shaft (15); the first star wheel (14) and the second star wheel (16) are respectively mounted on both sides of the annular protrusion on the outer circumferential surface; and annular grooves are respectively provided on the two end surfaces of the elastic shaft (15) along the circumferential direction.

5. The GTF engine gearbox with adjustable support stiffness according to claim 4, characterized in that: The bottoms of the annular grooves at both ends of the elastic shaft (15) are flush with the side walls of the annular protrusions, and the inner groove walls of the annular grooves close to the inner circumferential surface of the elastic shaft (15) are arc-shaped.

6. The GTF engine gearbox with adjustable support stiffness according to claim 4, characterized in that: Limiting rings (19) are respectively installed at both ends of the elastic shaft (15) for limiting the circumferential displacement of the first star wheel (14) and the second star wheel (16); gaskets are provided between the two limiting rings (19) and the elastic shaft (15); the gaskets are made of alloy steel and have an anti-slip layer on their surfaces.

7. The GTF engine gearbox with adjustable support stiffness according to claim 4, characterized in that: The sun gear (6) is an integral herringbone external gear, the inner gear ring (7) is an integral herringbone internal gear ring, and the helical angles of the first star gear (14) and the second star gear (16) are opposite in direction.

8. The GTF engine gearbox with adjustable support stiffness according to claim 1, characterized in that: The input shaft (5) is rotatably connected to the upper box cover (2) via a deep groove ball bearing, and an input shaft end cover (4) is fixedly provided at the outer end of the upper box cover (2) for positioning the input shaft (5).

9. The GTF engine gearbox with adjustable support stiffness according to claim 1, characterized in that: The output shaft (12) is rotatably connected to the lower box cover (10) via a spherical roller bearing, and an output shaft end cover (13) is fixedly disposed at an outer end of the lower box cover (10) for positioning the output shaft (12).

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