Support device

Abstract

A supporting device is used for supporting a fan shaft and comprises a force bearing frame, a first cone bearing, a second cone bearing and a corrugated pipe spring. The bearing frame comprises a first supporting leg and a second supporting leg which are axially spaced; the inner ring of the first cone bearing is fixed on a fan shaft, and the outer ring of the first cone bearing is arranged on the first supporting leg and allows axial movement; the second cone bearing is located on the rear side of the first cone bearing, the second cone bearing and the first cone bearing are oppositely arranged, an axial interval is formed between the second cone bearing and the first cone bearing, an inner ring is used for being fixed to a fan shaft, and an outer ring is fixed to the second supporting foot. The corrugated pipe spring abuts against the outer ring of the first cone bearing forwards and abuts against the outer ring of the first cone bearing towards the peripheral side, the corrugated pipe spring comprises an outer peripheral wall body, an inner peripheral wall body and a radial wall body which are connected with one another, a plurality of through holes are distributed in the radial wall body in the circumferential direction, and therefore a plurality of spokes are distributed in the circumferential direction.

Description

Technical Field

[0001] The present invention relates to the design technology of aeroengines, and particularly to a supporting device for supporting a fan shaft. Background Art

[0002] In a geared engine, a reduction gearbox is provided between a fan rotor and a low-pressure turbine rotor, so that the fan rotor and the low-pressure turbine rotor can operate respectively within their respective optimal rotational speed ranges. While the fan rotor maintains a low rotational speed, the rotational speed of the low-pressure turbine rotor can be significantly increased. The reduction of the fan rotor rotational speed can reduce the tip speed and root stress of the blades, making it possible to further increase the bypass ratio. The increase in the rotational speed of the low-pressure turbine rotor can improve the work efficiency of the turbine. Under the conditions of the same thrust and power levels, the number of turbine stages and blades can be significantly reduced.

[0003] A gearbox is provided between the fan and the low-pressure compressor, so that the fan shaft is an output shaft of an independent gearbox. To suppress the vibration transmitted by the fan shaft to the gearbox and enhance the angular stiffness of the fan rotor, as Figure 1 and Figure 2 shown, the fan shaft 3 is supported by a relatively arranged first tapered bearing 401 and second tapered bearing 402. On the entire force transmission path, the axial force F generated by the fan blades 1 is transmitted to the tapered bearings through the fan shaft 3, and then to the intermediate casing through the load-bearing frame 403, and finally transmitted to the aircraft through the mounting bracket. The fan shaft 3 undergoes axial elongation under the action of the axial force F. As the fan rotational speed increases, the generated axial force F increases, and the axial elongation amount of the fan shaft 3 increases, causing the operating parameters of the first tapered bearing 401 and the second tapered bearing 402 to deviate from the preset parameters, affecting the bearing life. Summary of the Invention

[0004] The purpose of the present invention is to provide a supporting device for ensuring the preload of the first tapered bearing.

[0005] According to an embodiment of the present invention, the supporting device is used to support the fan shaft. The supporting device includes a load-bearing frame, a first tapered bearing, a second tapered bearing, and a bellows spring; the load-bearing frame includes a first support leg and a second support leg that are axially spaced apart; the inner ring of the first tapered bearing is used to be fixed on the fan shaft, and the outer ring is disposed on the first support leg and allows axial movement; the second tapered bearing is located at the rear side of the first tapered bearing, is arranged opposite to the first tapered bearing and has an axial interval, the inner ring is used to be fixed on the fan shaft, and the outer ring is fixed on the second support leg; the bellows spring abuts against the outer ring of the first tapered bearing forward and abuts against the outer ring of the first tapered bearing on the outer peripheral side, and includes a peripheral wall body, an inner peripheral wall body, and a radial wall body that are connected to each other. The radial wall body is distributed with a plurality of through holes in the circumferential direction, so as to distribute a plurality of spokes in the circumferential direction.

[0006] In one or more embodiments, each of the spoke structures is the same, and the plurality of spokes are circumferentially and uniformly distributed on the radial wall body.

[0007] In one or more embodiments, each of the spokes is a straight plate extending radially.

[0008] In one or more embodiments, an axial convex ring is provided on the axial end face of the outer ring of the first tapered bearing, and the outer peripheral surface of the bellows spring abuts against the inner peripheral surface of the axial convex ring to abut against the outer ring of the first tapered bearing toward the outer peripheral side.

[0009] In one or more embodiments, a second radial stop is provided on the outer peripheral surface of the bellows spring, and the second radial stop abuts against the axial end face of the axial convex ring to abut against the outer ring of the first tapered bearing forward.

[0010] In one or more embodiments, a first radial stop is provided on the inner peripheral surface of the second support leg, and the axial end face of the bellows spring abuts against the first radial stop.

[0011] In one or more embodiments, the outer peripheral surface of the bellows spring abuts against the inner peripheral surface of the second support leg.

[0012] The embodiments of the present invention at least have the following beneficial effects:

[0013] 1. The bellows spring abuts against the outer ring of the first tapered bearing forward to ensure the preload of the first tapered bearing.

[0014] 2. By designing and adjusting the spokes, the axial stiffness of the bellows spring can be adjusted, and the radial stiffness of the bellows spring is basically not affected, so that the axial stiffness and the radial stiffness of the bellows spring are basically independent of each other, and the axial stiffness and the radial stiffness of the bellows spring can be designed separately to meet the requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The above and other features, properties, and advantages of the present invention will become more apparent from the following description in conjunction with the drawings and embodiments, wherein:

[0016] Figure 1 is a schematic structural diagram of a fan rotor;

[0017] Figure 2 is a schematic structural diagram of a support device;

[0018] Figure 3 is a schematic diagram of the dimension chain calculation of the support device;

[0019] Figure 4 is an oblique view of the bellows spring;

[0020] Figure 5 is a front view of the bellows spring;

[0021] Figure 6 It is a side view of a corrugated spring;

[0022] Figure 7 It is a schematic diagram of the equivalent design parameters of a corrugated spring;

[0023] Figure 8 It is a schematic flow diagram of the design method of a corrugated spring.

[0024] Reference numerals:

[0025] 1 - Fan blade;

[0026] 2 - Fan disk;

[0027] 3 - Fan shaft;

[0028] 4 - Support device;

[0029] 401 - First tapered bearing;

[0030] 402 - Second tapered bearing;

[0031] 403 - Load-bearing frame;

[0032] 404 - Corrugated spring;

[0033] 405 - Second foot;

[0034] 406 - First radial stop;

[0035] 407 - Second end of the corrugated spring;

[0036] 408 - Limiting sleeve;

[0037] 409 - First foot;

[0038] 410 - Axial ring;

[0039] 411 - First end of the corrugated spring;

[0040] 412 - Second radial stop;

[0041] 413 - Bushing;

[0042] 414 - Outer peripheral wall body of the corrugated spring;

[0043] 415 - Inner peripheral wall body of the corrugated spring;

[0044] 416 - Radial wall body of the corrugated spring;

[0045] 417 - Through hole;

[0046] 418 - Spoke;

[0047] 5 - Gear system. Detailed implementation

[0048] Now, reference will be made in detail to the embodiments of the present invention, one or more examples of which are shown in the accompanying drawings. Each example is provided to explain the present invention, not to limit it. In fact, it will be obvious to those skilled in the art that various modifications and variations can be made to the present invention without departing from the scope or spirit thereof. For example, features shown or described as part of one embodiment can be used with another embodiment to yield yet another embodiment. Accordingly, the present invention is intended to cover these modifications and variations that fall within the scope of the appended claims and their equivalents.

[0049] It should be noted that these and subsequent other drawings are only examples, and they are not drawn under the condition of equal scale, and should not be used to limit the actual scope of protection required by the present invention.

[0050] The terms "first", "second", etc. can be used interchangeably to distinguish one feature from another, and are not intended to indicate that each feature must be located in the position shown in each embodiment.

[0051] Figure 1 Exemplarily, a fan rotor of a high bypass ratio turbofan engine is shown. As Figure 1 shown, the fan blade 1 is installed on the fan disk 2, the fan disk 2 is installed at the front end of the fan shaft 3, the fan shaft 3 is the output shaft of an independent gear system 5, the rear end of the fan shaft 3 is connected to the gear system 5, and the fan shaft 3 is supported by a support device 4 in the middle. As Figure 2 shown, the support device 4 includes a first tapered bearing 401 and a second tapered bearing 402. The first tapered bearing 401 and the second tapered bearing 402 are arranged opposite to each other to enhance the bearing capacity of the axial load. The first tapered bearing 401 and the second tapered bearing 402 have an axial spacing to enhance the angular rigidity of the fan rotor. The first tapered bearing 401 is located on the front side of the second tapered bearing 402, closer to the fan disk 2, and the second tapered bearing 402 is located on the rear side of the first tapered bearing 401, farther from the fan disk 2. The inner rings of the first tapered bearing 401 and the second tapered bearing 402 are fixed on the fan shaft 3. The inner rings of the first tapered bearing 401 and the second tapered bearing 402 can be fixed to the fan shaft 3 by interference fit. The support device 4 further includes a load-bearing frame 403. The outer rings of the first tapered bearing 401 and the second tapered bearing 402 are supported on the load-bearing frame 403.

[0052] On the entire force transmission path, the axial force F generated by the fan blade 1 is transmitted through the fan shaft 3 to the first tapered bearing 401 and the second tapered bearing 402, and then through the load-bearing frame 403 to the intermediate casing, and finally through the mounting lug to the aircraft. Under the action of the axial force F, the fan shaft 3 undergoes axial elongation. The higher the fan speed, the greater the axial force F, and the greater the axial elongation of the fan shaft 3. The axial elongation of the fan shaft 3 causes the axial distance between the inner rings of the first tapered bearing 401 and the second tapered bearing 402 to increase. If the axial distance between the outer rings of the first tapered bearing 401 and the second tapered bearing 402 remains unchanged, it will lead to a decrease in the preload of the first tapered bearing 401, resulting in light-load slipping and affecting the bearing life. As Figure 2As shown, the support device 4 is provided with a bellows spring 404 to ensure the preload of the first tapered bearing 401. The load-bearing frame 403 includes a first leg 409 and a second leg 405 with an axial spacing. The first leg 409 is located on the front side of the second leg 405, closer to the fan disc 2, and the second leg 405 is located on the rear side of the first leg 409, farther from the fan disc 2. The outer ring of the second tapered bearing 402 is fixed to the second leg 405. The outer ring of the second tapered bearing 402 can be fixed to the second leg 405 by bolts. The outer ring of the first tapered bearing 401 is arranged on the first leg 409 and can move axially relative to the first leg 409. The outer ring of the first tapered bearing 401 can be arranged on the first leg 409 through a limit sleeve 408. The limit sleeve 408 allows the outer ring of the first tapered bearing 401 to move axially relative to the limit sleeve 408, thereby allowing the outer ring of the first tapered bearing 401 to move axially relative to the first leg 409. The limit sleeve 408 restricts the radial movement of the outer ring of the first tapered bearing 401. The first end 411 of the bellows spring 404 in the axial direction is installed on the outer ring of the first tapered bearing 401, pushing forward against the outer ring of the first tapered bearing 401 and against the outer peripheral side of the outer ring of the first tapered bearing 401. An axial convex ring 410 can be provided on the outer ring of the first tapered bearing 401. The outer peripheral surface of the first end 411 is in interference fit with the inner peripheral surface of the axial convex ring 410. The radial stiffness of the first tapered bearing 401 depends on the radial support stiffness of the bellows spring 404. The first end 411 pushes forward against the outer ring of the first tapered bearing 401. The second radial stop 412 of the first end 411 can abut against the axial end face of the axial convex ring 410. The axial end face of the first end 411 can be attached to the axial end face of the outer ring of the first tapered bearing 401 or have an axial gap with the axial end face of the outer ring of the first tapered bearing 401. The second end 407 of the bellows spring 404 in the axial direction can be installed on the second leg 405. The axial end face of the second end 407 abuts against the first radial stop 406 of the second leg 405, pushing backward against the second leg 405. The outer peripheral surface of the second end 407 abuts against the inner peripheral surface of the second leg 405 on the outer peripheral side. The first end 411 and the second end 407 of the bellows spring 404 are respectively pressed against the outer ring of the first tapered bearing 401 and the first radial stop 406 of the second leg 405 by the tension after pre-axial compression. The bellows spring 404 is always in an axially compressed state, pushing forward against the outer ring of the first tapered bearing 401 to ensure the preload of the first tapered bearing 401.

[0053] As Figure 2 shown, the support device 4 can also be provided with a bushing 413 to prevent the bellows spring 404 from being over-compressed. The bushing 413 is sleeved on the outer periphery of the fan shaft 3. The bushing 413 is arranged axially between the inner rings of the first tapered bearing 401 and the second tapered bearing 402. The first end of the bushing 413 abuts against the axial end face of the inner ring of the first tapered bearing 401, and the second end of the bushing 413 abuts against the axial end face of the inner ring of the second tapered bearing 402. As Figure 3As shown, A1 is the axial distance between the axial end face of the inner ring of the first tapered bearing 401 that is abutted by the bushing 413 and the axial end face of the outer ring that is abutted by the bellows spring 404 in a state without clearance and preload. A2 is the axial length of the bellows spring 404 in the free state without axial compression. A3 is the axial distance from the axial end face of the first radial stop 406 that is abutted by the second end 407 of the bellows spring 404 to the axial positioning rib of the outer ring of the second tapered bearing 402. A4 is the axial length of the bushing 413. A5 is the axial distance between the axial end face of the inner ring of the second tapered bearing 402 that is abutted by the bushing 413 and the axial positioning rib of the outer ring in a state without clearance and preload. The installation preload of the bellows spring 404 is δ2 = (A1 + A2 + A3) - (A4 + A5), which is the axial compression length when the bellows spring 404 is assembled in place. The bushing 413 prevents the assembled bellows spring 404 from being overcompressed. When the axial compression length of the bellows spring 404 when assembled in place is equal to the axial length of the bushing 413, that is, when the length A2 of the bellows spring 404 after axial compression makes (A1 + A2 + A3) = (A4 + A5), since the bushing 413 cannot be axially compressed, the bellows spring 404 cannot be further axially compressed, restricting the installation preload of the bushing 413 from being too large.

[0054] As Figure 4 shown, the bellows spring 404 may include an outer peripheral wall body 414, an inner peripheral wall body 415, and a radial wall body 416. The outer peripheral wall body 414 is an annular wall body located on the outer peripheral side, the inner peripheral wall body 415 is an annular wall body located on the inner peripheral side, and the radial wall body 416 is perpendicular to the axial direction and connects the outer peripheral wall body 414 and the inner peripheral wall body 415 in the radial direction, forming a "ji"-shaped corrugated structure. A plurality of through holes 417 are distributed in the circumferential direction on the radial wall body 416. The through holes 417 penetrate the radial wall body 416 in the axial direction, so that a spoke 418 is formed between every two adjacent through holes 417 in the circumferential direction, and a plurality of spokes 418 are distributed in the circumferential direction on the radial wall body 416. By designing the radial length, axial thickness, circumferential width of the spoke 418, and the number of spokes 418 distributed on the radial wall body 416, the axial stiffness of the bellows spring 404 can be adjusted, and the radial stiffness of the bellows spring 404 is basically not affected, so that the axial stiffness and radial stiffness of the bellows spring 404 are basically independent, and the axial stiffness and radial stiffness of the bellows spring 404 can be designed separately to meet the requirements.

[0055] As Figure 4 shown, a plurality of through holes 417 may be evenly distributed in the circumferential direction on the radial wall body 416, and a plurality of spokes 418 may be evenly distributed in the circumferential direction on the radial wall body 416. Further referring to Figure 5, the through hole 417 can be fan-shaped, the spoke 418 can be a straight plate extending radially, the radial length L of the spoke 418 can be the outer peripheral radius R of the fan-shaped through hole 417 minus the inner peripheral radius r, the circumferential width of the spoke 418 can be b. Further referring to Figure 6 , the axial thickness of the spoke 418 can be h. The spoke 418 can also be in other shapes, and the spokes 418 in other shapes can still have equivalent radial length L, circumferential width b, and axial thickness h. Each radial wall 416 of the bellows spring 404 can be provided with the aforementioned through hole 417 and spoke 418.

[0056] By ignoring the irregular structures such as the joints of the outer peripheral wall 414, the inner peripheral wall 415, the radial wall 416, and the arc segments, rounded corners, chamfers at the edges, the bellows spring 404 can be simplified to the regular geometric structure as shown in Figure 7 . Through the structural mechanics formula, the contribution of each segment of the outer peripheral wall 414, each segment of the inner peripheral wall 415, and each layer of the radial wall 416 to the radial deformation can be obtained, and then the radial stiffness of each segment of the outer peripheral wall 414, each segment of the inner peripheral wall 415, and each layer of the radial wall 416 can be obtained. For each segment of the outer peripheral wall 414, each segment of the inner peripheral wall 415, and each layer of the radial wall 416, the stiffness relationship between the generalized force and the generalized deformation is:

[0057]

[0058] where, [K] is the generalized stiffness matrix of each segment of the outer peripheral wall 414, each segment of the inner peripheral wall 415, and each layer of the radial wall 416. K Fy is the force required to generate a unit deflection. K Fθ is the force required to generate a unit rotation. K My is the moment required to generate a unit deflection. K Mθ is the moment required to generate a unit rotation. represents the 2×2 matrix composed of the above four parameters.

[0059] For each segment of the outer peripheral wall 414 and each segment of the inner peripheral wall 415:

[0060]

[0061] where, E is the elastic modulus of the material. I is the moment of inertia of the cross-section of this segment of the outer peripheral wall 414 / this segment of the inner peripheral wall 415. l is the axial length of this segment of the outer peripheral wall 414 / this segment of the inner peripheral wall 415.

[0062] For each layer of the radial wall 416:

[0063]

[0064] Among them, π is the pi. h is the axial thickness of the spoke 418. μ is the Poisson's ratio of the material. β is R1 / R2, where R1 is the radius of the outer peripheral wall body 414 and R2 is the radius of the inner peripheral wall body 415. E is the elastic modulus of the material. As shown in the formula, the contribution of the radial wall body 416 to the radial deformation is only the rotation angle under the moment, and the rest of the stiffness is ∞. Therefore, designing and adjusting the spoke 418 of the radial wall body 416 basically does not affect the radial stiffness of the bellows spring 404. The axial stiffness of the bellows spring 404 can be adjusted by designing and adjusting the spoke 418, so that the axial stiffness and the radial stiffness of the bellows spring 404 are basically not related, and the axial stiffness and the radial stiffness of the bellows spring 404 can be designed separately to meet the requirements.

[0065] The axial stiffness of the bellows spring 404 is calculated as:

[0066]

[0067] Among them, K is the axial stiffness of the bellows spring 404. n is the number of spokes 418 arranged circumferentially on each radial wall body 416. E is the elastic modulus of the material. b is the circumferential width of the spoke 418. h is the axial thickness of the spoke 418. m is the number of radial wall bodies 416. As shown in the figure, the bellows spring 404 is provided with four radial wall bodies 416, so m = 4. L is the radial length of the spoke 418, L = R - r, where R is the outer peripheral radius of the fan-shaped through hole 417 and r is the inner peripheral radius of the fan-shaped through hole 417. The stiffness K of a single radial wall body 416 l is expressed as The stiffness K of a single spoke 418 s is expressed as is obtained from the empirical formula of the squirrel cage.

[0068] As Figure 8 shown, the design process of the above-mentioned bellows spring 404 is as follows:

[0069] First, the maximum axial force of the fan shaft 3 under the maximum takeoff state of the engine, the range of the radial support stiffness requirements (Kr1, Kr2) of the fulcrum of the fan shaft 3, and the usage requirements of the first tapered bearing 401 are used as the inputs in the design process. The usage requirements of the first tapered bearing 401 are the range of the preload force (F 1 , F 2) First, according to the radial support stiffness range (Kr1, Kr2) and the axial spacing between the first tapered bearing 401 and the second tapered bearing 402 in the actual structure, the axial length l of each outer peripheral wall body 414 of the bellows spring 404, the axial length l of each inner peripheral wall body 415, the radius R2 of the outer peripheral wall body 414, the radius R1 of the inner peripheral wall body 415, and the axial length h of the spoke 418 are preliminarily designed so that the radial stiffness of the theoretically calculated bellows spring 404 is within the radial support stiffness range (Kr1, Kr2).

[0070] On this basis, the maximum increase amount δ of the axial spacing between the inner rings of the first tapered bearing 401 and the second tapered bearing 402 can be calculated through the maximum axial force of the fan shaft 3 under the maximum takeoff state of the engine. 1 , and the axial stiffness K of the bellows spring 404 is designed according to the usage requirements of the first tapered bearing 401. 0 And the installation pre-tightening amount δ is such that K 0 ·(δ - δ 1 ) ∈ (F 1 , F 2 ) and K 0 ·δ ∈ (F 1 , F 2 ). The purpose is to ensure that the pre-tightening force provided by the bellows spring 404 from the engine shutdown state to the maximum takeoff state, i.e., the state with the maximum axial force, is within the pre-tightening force requirement range for the stable operation of the first tapered bearing 401.

[0071] After determining the required K 0 , the circumferential width b, the outer end radius R, and the inner end radius r of the spoke 418 are designed through the empirical formula of the cage bar stiffness. The circumferential width b of the spoke 418 is approximately the axial length h of the spoke 418. The number n of the spokes 418 arranged circumferentially on each radial wall body 416 is preferably n ≥ 16. Then, the accurate axial stiffness K of the bellows spring 404 is calculated through finite element software. 1 , if K 1 is close to the design value K 0 , and also satisfies K 1 ·(δ - δ 1 ) ∈ (F 1 , F 2 ), K 0 ·δ ∈ (F 1 , F 2 ), then it can be considered that the axial stiffness of the bellows spring 404 meets the requirements; otherwise, the parameters of the spoke 418 are readjusted.

[0072] After completing the axial stiffness design of the bellows spring 404, the detailed shape of the bellows spring 404 can be determined, including the fillets, chamfers, and the arc transition sections of the outer peripheral wall body 414, the inner peripheral wall body 415, and the radial wall body 416. These structural designs are mainly for strength consideration to relieve the stress concentration of the structure and have little impact on the stiffness. After determination, the accurate radial stiffness value K is calculated by finite element software. 2 , if K 2 ∈ (Kr1, Kr2), the design is completed; otherwise, the axial lengths l of each section of the outer peripheral wall body 414, the axial lengths l of each section of the inner peripheral wall body 415, the radius R2 of the outer peripheral wall body 414, and the radius R1 of the inner peripheral wall body 415 can be readjusted without affecting the axial stiffness of the bellows spring 404 until K 2 ∈ (Kr1, Kr2), then the design is completed.

[0073] Although the present invention is disclosed as above with embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications without departing from the spirit and scope of the present invention.

Claims

1. A support device for supporting a fan shaft, characterized in that it comprises: a load-bearing frame including a first leg and a second leg with an axial spacing; a first tapered bearing, the inner ring of which is for fixing to the fan shaft, and the outer ring is arranged on the first leg and allows axial movement; a second tapered bearing, located at the rear side of the first tapered bearing, arranged opposite to the first tapered bearing with an axial spacing, the inner ring of which is for fixing to the fan shaft, and the outer ring is fixed to the second leg; and a bellows spring, which abuts forward against the outer ring of the first tapered bearing and abuts against the outer ring of the first tapered bearing towards the outer peripheral side, and includes an outer peripheral wall body, an inner peripheral wall body and a radial wall body connected to each other, and a plurality of through holes are distributed in the radial wall body along the circumferential direction, so that a plurality of spokes are distributed along the circumferential direction.

2. The support device according to claim 1, characterized in that: each of the spokes has the same structure, and the plurality of spokes are evenly distributed along the circumferential direction on the radial wall body.

3. The support device according to claim 2, characterized in that: each of the spokes is a straight plate extending in the radial direction.

4. The support device according to claim 1, characterized in that: an axial convex ring is arranged on the axial end face of the outer ring of the first tapered bearing, and the outer peripheral surface of the bellows spring abuts against the inner peripheral surface of the axial convex ring to abut against the outer ring of the first tapered bearing towards the outer peripheral side.

5. The support device according to claim 3, characterized in that: a second radial stop is arranged on the outer peripheral surface of the bellows spring, and the second radial stop abuts against the axial end face of the axial convex ring to abut forward against the outer ring of the first tapered bearing.

6. The support device according to claim 1, characterized in that: a first radial stop is arranged on the inner peripheral surface of the second leg, and the axial end face of the bellows spring abuts against the first radial stop.

7. The support device according to claim 1, characterized in that: the outer peripheral surface of the bellows spring abuts against the inner peripheral surface of the second leg.

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