An aero-engine accessory gearbox tail shaft fixing structure capable of axial compensation

Abstract

The application belongs to the field of casing design, and particularly relates to an aero-engine accessory casing tail shaft fixing structure capable of axial compensation, comprising a mandrel, an adapter shaft, a flying gear shaft and a casing shell. The interior of the adapter shaft is a hollow structure, the mandrel is coaxially arranged on the inner side of the adapter shaft, and one end of the mandrel is inserted into the flying gear shaft. The inner wall of one end of the adapter shaft is connected with the end of the flying gear shaft. The casing shell is arranged on the outer side of the mandrel, the adapter shaft and the flying gear shaft. Through the nested design of the mandrel and the adapter shaft, the original single long shaft is decomposed into the combined structure of the mandrel and the adapter shaft. One end of the mandrel is inserted into the flying gear shaft to form a short cantilever connection, and the other end is indirectly supported by the adapter shaft and the flying gear shaft. The design equivalently shortens the effective cantilever length L of the mandrel, reduces the L / D ratio of the whole tail shaft, and significantly improves the first-order critical speed and the critical speed margin of the tail shaft in combination with the radial support of the adapter shaft on the mandrel.

Description

Technical Field

[0001] This application belongs to the field of casing design, and specifically relates to a tail shaft fixing structure for an aero-engine accessory casing with axial compensation. Background Technology

[0002] To facilitate the layout of aircraft and engine accessories (fuel pump, hydraulic pump, generator, etc.) and control the engine's radial profile, an aircraft accessory housing 18 (hereinafter referred to as "aircraft accessory") and an engine accessory housing 19 (hereinafter referred to as "engine accessory") are generally provided. The aircraft accessory is fixed to the aircraft's load-bearing frame, and the engine accessory is fixed to the outside of the engine compressor. To accommodate load deformation under different installation references, the aircraft accessory and the engine accessory are connected by a flexible coupling 20 with angle compensation function. See [link to relevant documentation]. Figure 1 .

[0003] The part connecting the accessory housing and the flexible coupling is called the tail shaft. The tail shaft structure of the aircraft and engine has one end fully constrained and the other end axially floating. The structure of the fully constrained tail shaft end is shown in [reference needed]. Figure 2 The fully constrained end is secured to the fly attachment drive rod inside the fly attachment gear shaft by fastening nuts and spacer sleeves, and then fixed to the fly attachment housing by support bearings at both ends of the fly attachment gear shaft.

[0004] Figure 2 The structure is generally suitable for situations where dimensions L and D satisfy L < 1.5D. When L ≥ 1.5D, the tail shaft drive rod will become slender, and the critical speed margin will be greatly reduced. When the first-order critical speed margin is less than 20%, the system will not be able to work stably. In addition, after the rotor becomes slender, the radial load of the first support bearing will increase sharply, while the radial load of the second support bearing will decrease sharply. The bearing is prone to problems such as excessive contact stress and slippage under light load, which reduces reliability.

[0005] Therefore, how to improve the critical speed margin at the fully constrained end of the tail shaft is a problem that needs to be solved. Summary of the Invention

[0006] To address the aforementioned issues, this application provides an axially compensated tail shaft fixing structure for an aero-engine accessory casing, thereby resolving the problem of insufficient critical speed margin at the fully constrained end of the tail shaft in the prior art.

[0007] The technical solution of this application is: an axially compensateable tail shaft fixing structure for an aero-engine accessory casing, including a spindle, a transfer shaft, a flight gear shaft, and a casing housing;

[0008] The adapter shaft has a hollow internal structure. The spindle is coaxially located inside the adapter shaft, and one end of the spindle is inserted into the flying gear shaft. The inner wall of one end of the adapter shaft is connected to the end of the flying gear shaft. The casing is located outside the spindle, the adapter shaft, and the flying gear shaft.

[0009] A first bearing connects the adapter shaft to the casing housing, and a second and a third bearing connect the flying gear shaft to the casing housing. The third bearing is located at the tail of the casing housing. The first and second bearings provide radial constraint, and the third bearing provides axial constraint.

[0010] Preferably, the adapter shaft includes a support section and an expansion section; the support section is slidably fitted with the outer wall of the spindle, and the expansion section is connected to the flying gear shaft via a spline pair, wherein the diameter of the expansion section is larger than the diameter of the support section.

[0011] Preferably, a bending section is provided between the outward expansion section and the support section, the bending section is inclined, and an annular retaining ring is provided on the outer wall of the bending section, with the first bearing abutting against the annular retaining ring.

[0012] Preferably, the end of the casing is provided with a first journal and a top ring; a grate is provided between the first journal and the support section, and an inner sealing air cavity is formed between the first journal and the first bearing; the top ring is connected to the outer wall of the support section and bent inward, and an outer sealing cavity is formed between the top ring and the first journal, and the grate is connected between the inner sealing cavity and the outer sealing cavity.

[0013] Preferably, the mandrel includes a positioning section and a connecting section; the outer wall of the positioning section is a cylindrical positioning surface, which is positioned with the adapter shaft; the connecting section is connected to the flying gear shaft through a spline pair; the diameter of the positioning section is larger than that of the connecting section; the mandrel is capable of axial floating.

[0014] Preferably, the middle part of the casing is provided with a second journal, and the outer wall of the flying gear shaft is provided with a front convex ring and a rear convex ring. The front convex ring and the rear convex ring form a mounting seat. The outer ring of the second bearing is fitted with the stop of the second journal, and the inner ring is installed in the mounting seat. The second bearing is located on the outside of the connecting section.

[0015] The axially compensateable tail shaft fixing structure of the aircraft engine accessory casing of this application has the following advantages:

[0016] By using a nested design of the spindle and adapter shaft, the original single long shaft is decomposed into a combined structure of "spindle + adapter shaft": one end of the spindle is inserted into the flying gear shaft to form a short cantilever connection, and the other end is indirectly supported by the flying gear shaft through the adapter shaft. This design effectively shortens the effective cantilever length L of the spindle, reduces the overall L / D ratio of the tail shaft, and, combined with the radial support of the adapter shaft on the spindle, significantly improves the first-order critical speed and critical speed margin of the tail shaft.

[0017] It adopts a 3-axis rotor structure with axial and radial constraints on the outer shaft and axial floating of the spindle, which can transmit torque and compensate for axial displacement caused by the deformation of the positioning reference under load.

[0018] With the adoption of a 3-axis rotor structure and 3 bearing supports, this invention is applicable to Figure 3 The slender structure with L≥1.5D has a more stable working margin and load-bearing capacity;

[0019] The tail shaft, gears, seals and other components form a modular structure, making it a replaceable unit for both indoor and outdoor use, and offering better maintainability. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the flying attachment and launch attachment connection structure in the background art;

[0021] Figure 2 This is a schematic diagram of an axially floating tail shaft structure in the background technology;

[0022] Figure 3 This is a schematic diagram of the overall structure of this application.

[0023] 1. Spindle; 2. Adapter shaft; 3. First bearing; 4. Second bearing; 5. Aircraft attachment gear shaft; 6. Third bearing; 7. Support section; 8. Outward expansion section; 9. Bending section; 10. First journal; 11. Top ring; 12. Grate; 13. Positioning section; 14. Connecting section; 15. Second journal; 16. Front convex ring; 17. Rear convex ring; 18. Aircraft accessory housing; 19. Engine accessory housing; 20. Flexible coupling. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below with reference to the accompanying drawings. In the drawings, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The described embodiments are only a part of the embodiments of this application, not all of them. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without creative effort are within the scope of protection of this application. The embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0025] The first aspect of this application provides an axially compensateable tail shaft fixing structure for an aero-engine accessory casing, such as... Figure 3 As shown, it includes a spindle 1, a connecting shaft 2, a flying gear shaft 5, and a housing.

[0026] The adapter shaft 2 has a hollow internal structure. The spindle 1 is coaxially located inside the adapter shaft 2, and one end of the spindle 1 is inserted into the flying gear shaft 5. The inner wall of one end of the adapter shaft 2 is connected to the end of the flying gear shaft 5. The casing is located outside the spindle 1, the adapter shaft 2 and the flying gear shaft 5.

[0027] A first bearing 3 is connected between the adapter shaft 2 and the casing housing, and a second bearing 4 and a third bearing 6 are connected between the flying gear shaft 5 and the casing housing. The third bearing 6 is located at the tail of the casing housing. The first bearing 3 and the second bearing 4 can provide radial constraint, and the third bearing 6 can provide axial constraint to restrict the degrees of freedom in two directions.

[0028] By using a nested design of spindle 1 and adapter shaft 2, the original single long shaft is decomposed into a combined structure of "spindle 1 (short cantilever section) + adapter shaft 2 (support section 7)": one end of spindle 1 is inserted into the flying gear shaft 5 to form a short cantilever connection, and the other end is indirectly supported by the flying gear shaft 5 through adapter shaft 2. This design effectively shortens the effective cantilever length L of spindle 1, reduces the overall L / D ratio of the tail shaft (L is the cantilever length, D is the shaft diameter), and combined with the radial support of adapter shaft 2 on spindle 1, significantly improves the first-order critical speed and critical speed margin of the tail shaft.

[0029] Preferably, the adapter shaft 2 includes a support section 7 and an expansion section 9; the support section 7 is slidably fitted with the outer wall of the spindle 1, and the expansion section 9 is connected to the flying gear shaft 5 through a spline pair, and the diameter of the expansion section 9 is larger than the diameter of the support section 7.

[0030] By adopting a stepped shaft structure, the adapter shaft 2 is changed from being connected inside the flying gear shaft 5 to being connected externally, which provides space for the internal floating design while ensuring a stable connection.

[0031] Preferably, a bent section 8 is provided between the outwardly expanding section 9 and the supporting section 7. The bent section 8 is inclined, and an annular retaining ring is provided on the outer wall of the bent section 8. The first bearing 3 abuts against the annular retaining ring. The cooperation between the bent section 8 and the first bearing 3 improves the strength and stability of the connection of the adapter shaft 2.

[0032] Preferably, the end of the casing is provided with a first journal 10 and a top ring 11; a grate 12 is provided between the first journal 10 and the support section 7, and an inner sealing cavity is formed between the first journal 10 and the first bearing 3; the top ring 11 is connected to the outer wall of the support section 7 and bent inward, and an outer sealing cavity is formed between the top ring 11 and the first journal 10, with the grate 12 connecting the inner sealing cavity and the outer sealing cavity. The first bearing 3 is sealed by the cooperation of the outer sealing cavity and the inner sealing cavity, ensuring the stable operation of the first bearing 3.

[0033] Preferably, the spindle 1 includes a positioning section 13 and a connecting section 14; the outer wall of the positioning section 13 is a cylindrical positioning surface, which is positioned with the adapter shaft 2; the connecting section 14 is connected to the flying gear shaft 5 via a spline pair; the diameter of the positioning section 13 is larger than that of the connecting section 14; the spindle 1 is capable of axial floating. The spindle 1 transmits torque while simultaneously floating axially via the spline pair connection to compensate for the load deformation of the positioning reference and improve the critical speed margin of the axially floating end of the tail shaft.

[0034] Preferably, a second journal 15 is provided in the middle of the casing, and a front convex ring 16 and a rear convex ring 17 are provided on the outer wall of the flying gear shaft 5. The front convex ring 16 and the rear convex ring 17 form a mounting seat. The outer ring of the second bearing 4 is fitted with the stop of the second journal 15, and the inner ring is installed in the mounting seat. The second bearing 4 is located on the outer side of the connecting section 14. By providing the second bearing 4, the connection stability between the spindle 1 and the flying gear shaft 5 is improved, and the cooperation between the second journal 15 and the mounting seat ensures the stable operation of the second bearing 4, so that the spindle 1 will not deflect while floating. In summary, this application has the following advantages:

[0035] It adopts a 3-axis rotor structure with axial and radial constraints on the outer shaft and axial floating of the spindle, which can transmit torque and compensate for axial displacement caused by the deformation of the positioning reference under load.

[0036] With the adoption of a 3-axis rotor structure and 3 bearing supports, this invention is applicable to Figure 3 The slender structure with L≥1.5D has a more stable working margin and load-bearing capacity;

[0037] The tail shaft, gears, seals and other components form a modular structure, making it a replaceable unit for both indoor and outdoor use, and offering better maintainability.

[0038] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A tail shaft fixing structure for an aero-engine accessory casing with axial compensation, characterized in that, It includes a spindle (1), a connecting shaft (2), a flying gear shaft (5), and a casing; The adapter shaft (2) has a hollow structure inside. The spindle (1) is coaxially disposed inside the adapter shaft (2), and one end of the spindle (1) is inserted into the flying gear shaft (5). The inner wall of one end of the adapter shaft (2) is connected to the end of the flying gear shaft (5). The casing is disposed outside the spindle (1), the adapter shaft (2) and the flying gear shaft (5). The adapter shaft (2) is connected to the casing housing by a first bearing (3), and the flying gear shaft (5) is connected to the casing housing by a second bearing (4) and a third bearing (6). The third bearing (6) is located at the tail of the casing housing. The first bearing (3) and the second bearing (4) can provide radial constraint, and the third bearing (6) can provide axial constraint. The adapter shaft (2) includes a support section (7) and an expansion section (9); the support section (7) is slidably fitted with the outer wall of the spindle (1), and the expansion section (9) is connected to the flying gear shaft (5) through a spline pair; the diameter of the expansion section (9) is larger than the diameter of the support section (7). The end of the casing is provided with a first journal (10) and a top ring (11); a grate (12) is provided between the first journal (10) and the support section (7), and an inner sealing air cavity is formed between the first journal (10) and the first bearing (3); the top ring (11) is connected to the outer wall of the support section (7) and bent inward, and an outer sealing cavity is formed between the top ring (11) and the first journal (10), and the grate (12) is connected between the inner sealing cavity and the outer sealing cavity; The mandrel (1) includes a positioning section (13) and a connecting section (14); the outer wall of the positioning section (13) is a cylindrical positioning surface, which is positioned with the adapter shaft (2); the connecting section (14) is connected to the flying gear shaft (5) through a spline pair; the diameter of the positioning section (13) is larger than that of the connecting section (14); the mandrel (1) is capable of axial floating.

2. The axially compensateable tail shaft fixing structure for an aero-engine accessory casing as described in claim 1, characterized in that, A bending section (8) is provided between the outward expansion section (9) and the support section (7). The bending section (8) is inclined and an annular retaining ring is provided on the outer wall of the bending section (8). The first bearing (3) abuts against the annular retaining ring.

3. The axially compensateable tail shaft fixing structure for an aero-engine accessory casing as described in claim 1, characterized in that, The casing housing has a second journal (15) in the middle. The outer wall of the flying gear shaft (5) is provided with a front protruding ring (16) and a rear protruding ring (17). The front protruding ring (16) and the rear protruding ring (17) form a mounting seat. The outer ring of the second bearing (4) is fitted with the stop of the second journal (15), and the inner ring is installed in the mounting seat. The second bearing (4) is located on the outside of the connecting section (14).

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