CN113503305A

CN113503305A - Long and thin flexible shaft structure of sectional type engine

Info

Publication number: CN113503305A
Application number: CN202110886930.1A
Authority: CN
Inventors: 何康; 陈竞炜; 赵勇铭; 贺宜红; 聂建豪
Original assignee: Hunan Aviation Powerplant Research Institute AECC
Current assignee: Hunan Aviation Powerplant Research Institute AECC
Priority date: 2021-08-03
Filing date: 2021-08-03
Publication date: 2021-10-15

Abstract

The invention discloses a slender flexible shaft structure of a sectional engine, which relates to the technical field of gas turbine engines and comprises a front section shaft and a rear section shaft, wherein the front section shaft and the rear section shaft are fixedly connected through a front section shaft mounting edge and a rear section shaft mounting edge to form a whole, so that the front section shaft transmits rotor torque and bears axial force; the rear section shaft does not transmit torque and bear axial force, and is provided with two roller bearings which are borne by bearing seats respectively fixedly connected with two engine casings. According to the invention, through a sectional type slender flexible shaft structure, an elastic support and two bearing inner rings are integrated on a section of flexible shaft, and oil film damping is applied on a bearing outer ring, so that a complete rotor elastic support and an oil film squeezing system are formed; the bearing inner ring structure on the rear section shaft can simplify production and assembly and improve the functional integration of the shaft; the squirrel-cage flexible shaft structure can replace an elastic support to adjust the critical rotating speed of the rotor and control the radial deformation of the rotor.

Description

Long and thin flexible shaft structure of sectional type engine

Technical Field

The invention belongs to the technical field of gas turbine engines, and particularly relates to a sectional type engine slender flexible shaft structure.

Background

Existing gas turbine engines typically output shaft power through an elongated flexible shaft that in turn drives a rotor, propeller, fan, or compressor. Because the rotating shaft and the rotating part on the shaft have eccentric mass, centrifugal inertia force is inevitably generated during high-speed rotation to generate bow-shaped rotation, and the dynamic deflection reaches the maximum under the corresponding critical rotating speed to further generate damage. Therefore, the engine rotor system generally adopts an elastic support and an extruded oil film structure, on one hand, the critical rotating speed of the rotor is adjusted and controlled through the elastic support, so that the working rotating speed interval of the engine is kept away from the critical rotating speed; on the other hand, the energy of the rotor vibration is absorbed through the oil film damping effect, and the influence caused by the vibration is reduced.

In the existing gas turbine engine rotor supporting system, the reasonable arrangement of the critical rotating speed is an important prerequisite for ensuring the normal operation of the engine, so that a separate elastic support and oil film damping structure are generally required to be established. The classical rotor support system generally comprises a complete shaft, a complete bearing (comprising an inner ring and an outer ring, corresponding axial limiting members and locking members such as nuts and the like) is nested on the shaft, an elastic support is continuously nested on the outer ring of the bearing, and finally an oil film damping system is applied on the outer ring of the elastic support.

Accordingly, the present invention provides a segmented engine elongated flexible shaft structure that solves the problems set forth in the background above.

Disclosure of Invention

The invention aims to provide a sectional type engine slender flexible shaft structure, which aims to solve the following technical problems:

1) the existing rotor supporting system ensures the normal working and running of the rotor by setting up an independent elastic support, a complete bearing and an oil film damping structure, so that parts are machined, the assembly is complex, and the reduction of the number of the parts and the quality of an engine are not facilitated;

2) the whole rigidity of the existing shaft is deviated, so that the rigidity of a supporting system is reduced to meet the requirement of low critical rotating speed, the deformation of a rotor is increased, the radial clearance of the rotor and the stator is not controlled conveniently, the efficiency of an engine is reduced, and the risk of radial collision and abrasion of the rotor and the stator is caused.

According to one aspect of the invention, a sectional type engine slender flexible shaft structure is provided, which comprises a front section shaft and a rear section shaft, wherein the front section shaft and the rear section shaft are fixedly connected through a front section shaft mounting edge and a rear section shaft mounting edge to form a whole, so that the front section shaft transmits rotor torque and bears axial force;

the rear section shaft does not transmit torque and bear axial force, a first roller bearing and a second roller bearing are mounted on the rear section shaft, the first roller bearing and the second roller bearing are both borne by bearing blocks, and the bearing blocks are fixedly connected with a first engine casing and a second engine casing respectively.

According to an exemplary embodiment of the present invention, the rear section shaft is provided with a first bearing inner ring and a second bearing inner ring which are matched with the first rolling rod bearing and the second rolling rod shaft.

According to another exemplary embodiment of the present invention, the structure of the rear section shaft between the first bearing inner ring and the second bearing inner ring is a squirrel cage structure, which is an elastic structure.

According to another exemplary embodiment of the present invention, the first and second roller bearings comprise a first and second bearing outer ring, respectively, the bearing housing comprises a first and second bearing housing support, the first and second bearing outer ring being nested within the first and second bearing housing support, respectively.

According to another exemplary embodiment of the present invention, the first bearing outer ring and the second bearing outer ring are in clearance fit or interference fit with the bearing seat, and the first bearing outer ring and the second bearing outer ring are in two sets of fit with the first bearing seat bracket and the second bearing seat bracket correspondingly.

According to another exemplary embodiment of the present invention, at least one of the first bearing outer ring and the first bearing support and the second bearing outer ring and the second bearing support is a clearance fit, wherein two packing rings are arranged between the clearance fit group.

According to another exemplary embodiment of the invention, the clearance fit has a one-sided spacing of 0.1-0.4 mm.

According to another exemplary embodiment of the invention, an annular cavity is formed between the two sealing piston rings and the correspondingly assembled bearing outer ring and bearing seat support, and lubricating oil is injected into the annular cavity to form oil film damping.

Compared with the prior art, the invention has the beneficial effects that:

1. according to the invention, through a sectional type slender flexible shaft structure, an elastic support and two bearing inner rings are integrated on a section of flexible shaft, and oil film damping is applied on a bearing outer ring, so that a complete rotor elastic support and an oil film squeezing system are formed; the front section shaft outputs power at the front end of an engine to drive a rotor wing, a propeller, a fan and the like, and the tail end of the front section shaft is connected with a turbine rotor to transmit torque and pneumatic axial force; the rear section shaft is connected with the front section shaft through a connecting structure, does not bear torque transmission and axial force, only bears radial force and is used for mounting bearing components such as a bearing and the like, the rear section shaft is in an elastic supporting mode, a squirrel-cage structure is adopted, the rigidity of the shaft is reduced, the function of independent elastic supporting is basically replaced, and the critical rotating speed and the strain energy of the rotor are adjusted.

2. Compared with a common rotor supporting system, the invention integrates the inner rings of the two bearings on the rear-section shaft, thereby omitting complex axial limiting parts, locking parts and the like, further simplifying the structure, improving the functional integration level of the shaft, simultaneously simplifying the structures such as independent elastic support, the inner rings of the bearings and the like, further lightening the weight and optimizing the assembly.

3. The squirrel-cage structure is an elastic structure, the local rigidity of the shaft can be reduced, the rigidity value of the shaft can be changed by properly adjusting the length, the cross-sectional area and the like of the squirrel-cage branches, the critical rotating speed of the rotor is reduced, and the distribution of strain energy is adjusted.

4. The oil film damping structure is directly integrated between the outer rings of the two bearings and the bearing seat, and an oil film is formed to consume vibration energy when the rotor works, so that the rotor has wider rotating speed margin and stronger vibration load bearing capacity.

Drawings

In order to facilitate understanding for those skilled in the art, the present invention will be further described with reference to the accompanying drawings.

FIG. 1 is a schematic diagram of a typical support system having independent resilient supports and a complete bearing structure;

FIG. 2 is a sectional view of a segmented engine elongated flexible shaft structure;

FIG. 3 is a schematic diagram of a squirrel cage configuration;

fig. 4 is a sectional view a-a of fig. 3.

In the figure: 1. a front section shaft; 11. the front section shaft is provided with an edge;

2. a rear section shaft; 21. a rear section shaft mounting edge; 22. a first bearing inner ring; 23. a second bearing inner ring; 24. a squirrel cage structure;

3. a first roller bearing; 31. a first sealing piston ring; 32. a second packing piston ring; 33. a first bearing outer ring;

4. a second roller bearing; 41. a third packing piston ring; 42. a fourth packing piston ring; 43. a second bearing outer ring;

5. a bearing seat; 51. a first bearing support; 52. a second bearing block support; 53. a first bearing mount mounting edge; 54. a second bearing block mounting edge; 55. a thin outer wall of the bearing seat;

6. a first engine case; 7. a second engine case; 8. an elastic support; 9. a locking member; 10. an axial stop.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention are further described in detail below by way of examples with reference to the accompanying drawings. In the specification, the same or similar reference numerals denote the same or similar components. The following description of the embodiments of the present invention with reference to the accompanying drawings is intended to explain the general inventive concept of the present invention and should not be construed as limiting the structure of a segmented engine elongated flexible shaft of the present invention.

Furthermore, in the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the disclosure. It may be evident, however, that one or more embodiments may be practiced without these specific details. In other instances, well-known structures and devices are shown in schematic form in order to simplify the drawing.

As shown in figure 1, a typical stator adopts an independent elastic support 8, a shaft has a structure with higher rigidity, and when a rotor rotates at high speed and an aircraft maneuvers to generate gyroscopic moment, the radial deformation of the rotor is larger, so that the rotor and stator blades of an engine are easy to rub against each other, or larger rotor and stator blade gaps are adopted, but the performance loss of the engine is increased, and the thermal efficiency of the engine is reduced.

According to a general technical concept of the present invention, as shown in fig. 2-4, a sectional type engine slender flexible shaft structure is provided, which comprises a front section shaft 1, a rear section shaft 2, a first roller bearing 3, a second roller bearing 4, a bearing seat 5, a first engine casing 6 and a second engine casing 7; different from the rotor supporting system shown in fig. 1, the stator elastic support 8 nested with the bearing outer ring is eliminated, and a squirrel-cage structure 24 is machined on the rear-section shaft 2; a series of structures such as a locking piece 9, a bearing inner ring and an axial limiting piece 10 are omitted, and the function of the bearing inner ring is integrated by the rear-section shaft 2. The front section shaft 1 outputs power at the front end of an engine to drive a rotor wing, a propeller, a fan and the like, the tail end of the front section shaft 1 is connected with a turbine rotor, the power of the turbine rotor is output to the front end through torque, and the power bears pneumatic axial force; the rear section shaft 2 is connected with the front section shaft 1 through a connecting structure, and the squirrel cage structure has insufficient torsion resistance, so that the rear section shaft does not bear torque and axial force, only bears radial force and is used for mounting bearing components such as bearings and the like; the rear section shaft 2 is in the form of an elastic support 8, a squirrel-cage structure 24 is adopted between the axial spans of the first bearing inner ring 22 and the second bearing inner ring 23, the rigidity of the shaft is reduced, the function of the independent elastic support 8 at the bearing outer ring is basically replaced, and the critical rotating speed of a rotor is adjusted to avoid each working rotating speed of an engine, so that the normal operation of the engine is met.

Further, the front section shaft 1 is connected with the rear section shaft 2 through the front section shaft mounting edge 11, so that the two sections of shafts are connected into a whole, the two sections of shafts are used for transmitting torque and bearing pneumatic axial force, the connection with the turbine rotor of the engine can also be realized through the front section shaft mounting edge 11, or the two sections of shafts are connected through other structures such as an additional mounting edge and a spline, so that the pneumatic torque and the axial force of the turbine rotor are borne, the front end of the turbine rotor is extended to the front end of the engine to output mechanical work, and the schematic diagram is a typical schematic diagram and is only a cut-off diagram in fig. 2; the front section shaft 1 is installed without a bearing close to the rear section shaft 2.

Correspondingly, the rear section shaft 2 is also connected with the front section shaft 1 through the rear section shaft mounting edge 21, and does not bear axial force and transfer torque; a first bearing inner ring 22, a squirrel-cage structure 24 and a second bearing inner ring 23 are axially and sequentially integrated on the rear-section shaft 2, so that the structure is further simplified, and the function integration level of the shaft is improved; the first bearing inner ring 22 and the second bearing inner ring 23 can be respectively and directly matched and contacted with the rolling rods of the first rolling rod bearing 3 and the second rolling rod bearing 4 to bear the action of a rolling runway, corresponding independent bearing inner rings, axial limiting pieces 10, locking pieces 9 and other parts can be omitted, and the first rolling rod bearing 3 and the second rolling rod bearing 4 do not bear axial force; the squirrel-cage structure 24 is shown in fig. 3 and 4, can reduce the local rigidity of the shaft, can change the rigidity value of the shaft by properly adjusting the length L, the cross-sectional area (a x b) and the like of the squirrel-cage branch, can be adjusted in coordination with the rigidity value of the bearing support, can reduce the critical rotating speed of the rotor, and adjust the distribution of strain energy.

In the first embodiment, the first roller bearing 3 and the second roller bearing 4 respectively comprise the first bearing outer ring 33 and the second bearing outer ring 43 which are independent, and can be in small clearance fit with the first bearing seat bracket 51 and the second bearing seat bracket 52, and the single side is generally 0.1-0.4 mm; annular grooves along the circumferential direction are processed on the peripheries of the first bearing outer ring 33 and the second bearing outer ring 43 and can be combined with the first sealing piston ring 31 and the second sealing piston ring 32 to form a closed cavity respectively, so that an oil film damping structure is realized; when lubricating oil with certain pressure is injected into a circular cavity formed by the first bearing outer ring 33, the first bearing seat support 51, the first sealing piston ring 31 and the second sealing piston ring 32, an oil film damping function can be generated, and oil film consumption vibration energy is formed when the rotor works; similarly, the circular cavity formed by the second bearing outer ring 43, the second bearing seat support 52, the third sealing piston ring 41 and the fourth sealing piston ring 42 has similar functions to the circular cavity described above, and is not described again.

In the second embodiment, the first roller bearing 3 may include an independent first bearing outer ring 33, and may be in interference fit with the first bearing seat bracket 51, so as to omit the structures of the first sealing piston ring 31 and the second sealing piston ring 32, and have no oil film damping function; meanwhile, the second roller bearing 4 and the second bearing seat support 52 need to be in close clearance fit, generally with a single side of 0.1-0.4mm, and a circular cavity formed by the second bearing outer ring 43, the second bearing seat support 52, the third sealing piston ring 41 and the fourth sealing piston ring 42 has an oil film damping function.

In the third embodiment, the small clearance fit between the first roller bearing 3 and the first bearing seat support 51 is required, generally 0.1-0.4mm on one side, and at this time, the annular cavity formed by the first bearing outer ring 33, the first bearing seat support 51, the first sealing piston ring 31 and the second sealing piston ring 32 has an oil film damping function; meanwhile, the second roller bearing 4 and the second bearing seat support 52 are in interference fit, so that the structures of the third sealing piston ring 41 and the fourth sealing piston ring 42 are omitted, and the oil film damping function is not provided any more.

The two ends of the bearing seat 5 are connected with the first engine casing 6 and the second engine casing 7 through a first bearing seat mounting edge 53 and a second bearing seat mounting edge 54, and the bearing seat is used for supporting a rotor and transmitting rotor load to the first engine casing 6 and the second engine casing 7 of the casings; the first bearing seat support 51 and the second bearing seat support 52 mutually transmit load through a bearing seat thin outer wall 55, the first bearing seat support 51, the second bearing seat support 52 and the bearing seat thin outer wall 55 form a closed outer surface and a bearing cavity, the typical thickness of the bearing seat thin outer wall 55 is 1-1.5 mm, the bearing seat thin outer wall is of a thin-wall structure, and the bearing seat thin outer wall, the first engine case 6 and the second engine case 7 form a low-rigidity supporting system together; the bearing block 5 is also generally integrated or equipped with functions of lubricating oil supply, oil return, sealing cooling, ventilation and the like, which are not shown in detail in the example drawings.

The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are only exemplary embodiments of the present invention, and are not intended to limit the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A segmented engine elongated flexible shaft structure, comprising:

the front section shaft (1) and the rear section shaft (2) are fixedly connected through a front section shaft mounting edge (11) and a rear section shaft mounting edge (21) to form a whole, so that the front section shaft (1) transmits rotor torque and bears axial force;

install first roller bearing (3) and second roller bearing (4) on back end axle (2), first roller bearing (3) and second roller bearing (4) all bear through bearing frame (5), bearing frame (5) respectively with first engine machine casket (6) and second engine machine casket (7) fixed connection.

2. A segmented engine elongated flexible shaft structure according to claim 1, characterized in that the rear segment shaft (2) is provided with a first bearing inner ring (22) and a second bearing inner ring (23) adapted to the first roller bearing (3) and the second roller bearing (4).

3. A segmented engine elongated flexible shaft structure according to claim 2, characterized in that the structure of the rear segment shaft (2) between the first bearing inner ring (22) and the second bearing inner ring (23) is a squirrel cage structure (24), the squirrel cage structure (24) being an elastic structure.

4. A segmented engine elongated flexible shaft structure according to claim 1, characterized in that the first and second roller bearings (3, 4) comprise a first bearing outer ring (33) and a second bearing outer ring (43), respectively, and the bearing housing (5) comprises a first bearing housing support (51) and a second bearing housing support (52), the first bearing outer ring (33) and the second bearing outer ring (43) being nested in the first bearing housing support (51) and the second bearing housing support (52), respectively.

5. A segmented engine elongated flexible shaft structure according to claim 4, characterized in that the first bearing outer ring (33) and the second bearing outer ring (43) are in clearance fit or interference fit with the bearing seat (5), and the first bearing outer ring (33) and the second bearing outer ring (43) are in two sets of fit with the first bearing seat support (51) and the second bearing seat support (52) correspondingly.

6. A segmented engine elongated flexible shaft structure according to claim 5, characterized in that at least one of the first bearing outer ring (33) and the first bearing support (51) and the second bearing outer ring (43) and the second bearing support (52) is a clearance fit, wherein two packing collars are fitted between the clearance fit set.

7. A segmented engine elongate flexible shaft arrangement as claimed in claim 6, wherein the clearance fit is 0.1-0.4mm single sided.

8. A segmented engine elongated flexible shaft structure according to claim 6, characterized in that an annular cavity is formed between two said sealed piston rings and the correspondingly assembled bearing outer ring and bearing seat (5) bracket, and lubricating oil is injected into the annular cavity to form oil film damping.