A turbine shaft heat insulation structure

Abstract

The present invention belongs to the technical field of mechanical structures, and relates to a turbine shaft. A turbine shaft heat insulation structure is disclosed, wherein the turbine shaft comprises a cylindrical section, a conical section and an annular adapter plate, wherein the annular adapter plate is connected to the turbine disk by a plurality of bolts; the cylindrical section is interference-fitted with the inner ring of the bearing; the cylindrical section is hollow; and the mating surface of the annular adapter plate and the turbine disk is provided with a plurality of annular grooves concentric with the turbine shaft. The mating surface of the annular adapter plate and the turbine disk is also provided with a plurality of petal-shaped depressions, which are symmetrically distributed at equal intervals along the circumference of the annular adapter plate. The contact area is reduced, and at the same time, there will be air with poor heat transfer efficiency inside the groove, which further reduces the heat conducted. In order to avoid the formation of a dead cavity in the groove and limit the expansion of the gas in the groove, a petal-shaped depression is further added to the mating end surface of the annular adapter plate and the turbine disk, which is beneficial to the discharge of gas and further reduces the contact area.

Description

Technical Field

[0001] The present invention belongs to the technical field of mechanical structures and relates to a turbine shaft, and in particular to a turbine shaft heat insulation structure. Background Art

[0002] The turbine shaft of an aircraft engine plays the role of transmitting turbine shaft power and providing the shaft diameter of the bearing fulcrum, and is an important part of the turbine rotor. The large end of the turbine shaft is connected to the turbine disk, and the small end is connected to the compressor rotor. To withstand the heat transmitted from the turbine disk and avoid damage caused by excessive bearing temperature, active cooling technology and thermal insulation cooling technology are currently used.

[0003] Active Cooling Technology:

[0004] The active cooling technology of turbine bearings mainly uses compressor bleed air for bearing cavity ventilation cooling and lubricating oil lubrication cooling.

[0005] The main disadvantage of active cooling technology is that it cannot cool the engine after it stops, which will cause the bearing temperature to rise after it stops.

[0006] Adiabatic Cooling Technology:

[0007] The existing heat insulation cooling structure mainly adds a heat insulation screen and uses two air flows in the combustion chamber for heat insulation, thereby reducing heat conduction and heat radiation to the bearing cavity.

[0008] The main disadvantage of the existing thermal insulation cooling structure is that it is greatly affected by the structural size and cannot cut off the heat conduction from the turbine disk to the turbine shaft. Summary of the invention

[0009] Purpose of the invention: In view of the problems mentioned in the background technology, a turbine shaft insulation structure is proposed to reduce heat conduction to the turbine bearing during engine operation and after shutdown, and control the bearing temperature.

[0010] The technical solution of the present invention is:

[0011] A turbine shaft heat insulation structure, the turbine shaft comprises a cylindrical section, a conical section and an annular adapter plate, the annular adapter plate is connected to the turbine plate by a plurality of bolts; the cylindrical section is interference fit with the inner ring of the bearing; the cylindrical section is hollow;

[0012] The mating surfaces of the annular adapter disc and the turbine disc are provided with a plurality of annular grooves which are concentric with the turbine shaft.

[0013] Furthermore, the mating surface between the annular adapter disk and the turbine disk is also provided with a plurality of petal-shaped depressions, and the plurality of petal-shaped depressions are symmetrically distributed at equal intervals along the circumference of the annular adapter disk.

[0014] Furthermore, the petal-shaped depression is located in the annular groove area, and a petal-shaped depression is provided between every two bolts. The annular adapter plate and the turbine plate are fixed by multiple tension bolts. Due to the presence of the tension bolt holes, the circumferential groove will be discontinuous, so a petal-shaped depression is added between every two tension bolt holes to ensure the connectivity of the circumferential groove.

[0015] Furthermore, the conical section is provided with a plurality of cooling air holes penetrating the inner and outer surfaces of the conical section, and the cooling air holes are evenly spaced along the circumference of the conical section. During operation, the cooling air introduced by the compressor passes through the cooling air holes to take away the heat of the turbine shaft, while reducing the heat conducted from the turbine disk to the turbine shaft.

[0016] Furthermore, the number of cooling holes is the same as the number of petal-shaped depressions, and the angular directions of the cooling holes correspond to the angular directions of the petal-shaped depressions. In order to enhance the rotational pumping effect of the petal-shaped depressions, the number of cooling holes opened in the conical section is the same as the number of petal-shaped depressions, and the angular directions correspond to each other, thereby enhancing the cooling effect at all locations.

[0017] Furthermore, the total area of ​​the annular groove does not exceed 60% of the area of ​​the matching surface of the annular adapter disk and the turbine disk; the depth of the annular groove does not exceed 10% of the axial width of the annular adapter disk.

[0018] Furthermore, the outer surface of the cylindrical section and the inner ring of the bearing is provided with a plurality of axial grooves at equal intervals along the circumference of the cylindrical section. The lubricating oil can further cool the inner surface of the inner ring of the bearing through the axial grooves, and the oil returns by gravity after cooling. This measure can enhance the active cooling effect and reduce the temperature of the inner ring of the bearing.

[0019] Furthermore, the axial length of the cylindrical section groove is greater than the axial length of the bearing inner ring, which facilitates the design and use of the bearing inner ring disassembly tooling.

[0020] Furthermore, the depth of the axial groove does not exceed 10% of the wall thickness of the cylindrical section of the turbine shaft; and the sum of the widths of the multiple axial grooves does not exceed 50% of the circumference of the cylindrical section.

[0021] Furthermore, the non-bearing inner ring matching area of ​​the cylindrical section is provided with a plurality of radial cooling air holes at equal intervals along the circumference of the cylindrical section, which can ensure that the cooling air enters the inner cavity of the turbine shaft evenly and avoid the situation where the local cooling effect is poor. Under the premise that the strength of the turbine shaft allows and the cooling system meets the requirements, the more the better, and it is best to arrange them along multiple sections in the axial direction.

[0022] The present invention has the following beneficial effects: when the engine is working, the grooves and petal-shaped depressions of the turbine shaft can passively reduce the heat transferred from the turbine disk to the turbine shaft, the cooling air holes can realize the cooling of the turbine shaft, the shaft diameter grooves can realize the reduction of the heat transfer of the inner ring of the turbine axial bearing, and can also realize the cooling of the lubricating oil at the bottom of the inner ring. When the engine is stopped, the cooling air disappears, and the structures such as the grooves, depressions and grooves can still achieve the effect of reducing the transferred heat. Therefore, when the engine is working and stopped, the new turbine shaft heat insulation structure can achieve good heat insulation and control the bearing temperature within a reasonable range. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the heat insulation structure in the background technology;

[0024] Figure 2 This is a schematic diagram of the overall structure of the turbine shaft of the present invention;

[0025] Figure 3 It is a cross-sectional schematic diagram of the cooperation between the turbine shaft and the turbine disk of the present invention;

[0026] Figure 4 It is a partial enlarged view of A of the present invention;

[0027] Figure 5 It is a partial enlarged view of B of the present invention;

[0028] 1-groove, 2-petal-shaped depression, 3-axial groove, 4-cooling air hole, 5-bearing inner ring matching area, 6-turbine shaft, 7-turbine disk, 8-bearing inner ring. DETAILED DESCRIPTION

[0029] This section is an embodiment of the present invention, which is used to explain and illustrate the technical solution of the present invention.

[0030] The existing turbine shaft active cooling structure is shown in Figure 1 The bearing is mainly cooled by spraying lubricating oil, and the bearing cavity is ventilated and cooled by the compressor rear bleed air. During the operation of the engine, a good cooling effect is achieved, and a heat shield is used to reduce the heat transferred to the bearing cavity.

[0031] The turbine shaft heat insulation structure proposed by the present invention is shown in Figure 2. The turbine shaft includes, from left to right, a cylindrical section, a conical section, and an annular adapter plate; the turbine shaft 6 serves as the fulcrum of the turbine bearing, and its cylindrical section is interference fit with the inner ring 8 of the bearing; the connection between the annular adapter plate and the turbine disk 7 is improved by tightening bolts to increase the axial tension, and the end face fit ensures the connection reliability. Based on the principle of heat transfer that reducing the contact area can reduce heat transfer when other conditions remain unchanged, multiple annular grooves 1 concentric with the turbine shaft are added to the mating surface of the annular adapter plate and the turbine disk; a petal-shaped depression 2 structure is added to the mating surface of the annular adapter plate and the turbine disk, and multiple petal-shaped depressions are symmetrically distributed at equal intervals along the circumference of the annular adapter plate; multiple axial grooves 3 are arranged at equal intervals along the circumference in the area of ​​the cylindrical section and the inner ring of the bearing mating surface 5, all of which are based on the principle of reducing the contact area and reducing the heat conduction to control the heat dissipation to the bearing. At the same time, cooling holes 4 are added to the cylindrical section and the conical section to actively reduce the heat transfer.

[0032] Specifically, if Figure 3 As shown, during operation, the cooling air introduced by the compressor passes through the cooling air holes 4 of the cylindrical section and the conical section, taking away the heat of the turbine shaft and reducing the heat conducted by the turbine disk to the turbine shaft. The opening position, number and aperture of the cooling air holes must be determined after the cooling system calculation and the strength calculation of the turbine shaft.

[0033] like Figure 5 As shown, during the operation of the bearing, there is a special lubricating oil nozzle to spray lubricating oil on the bearing for lubrication and cooling. The cooled lubricating oil enters the oil return circuit under the action of gravity. At the same time, since multiple axial grooves 3 are added to the matching surface area of ​​the inner ring of the cylindrical section bearing, the lubricating oil can further cool the inner surface of the inner ring of the bearing through the axial grooves, and the oil returns by gravity after cooling. This measure can enhance the active cooling effect and reduce the temperature of the inner ring of the bearing.

[0034] like Figure 4 As shown, multiple circumferential grooves 1 are added to the end faces of the annular adapter disk and the turbine disk to reduce the contact area. At the same time, air with poor heat transfer efficiency will exist inside the grooves, further reducing the heat conducted. The reason why radial grooves are not designed is to ensure that no cooling air leakage occurs radially here.

[0035] In order to avoid the formation of dead space in the groove and limit the expansion of the gas in the groove, a petal-shaped depression 2 is further opened on the mating end surface of the annular adapter disk and the turbine disk, which is conducive to the discharge of gas and further reduces the contact area. At the same time, as the turbine shaft rotates, a pumping effect will be generated on the cooling gas in the disk cavity, increasing the flow of cooling gas to the petal-shaped depression position and entering the axial groove at the same time, further enhancing cooling.

[0036] After the engine is stopped, there is no cooling air for active cooling and no lubricating oil for lubrication and cooling. The heat of the turbine disk will continue to transfer to the turbine shaft. Although the active cooling measures have failed, passive insulation measures such as grooves are still effective and can still significantly reduce the heat transfer from the turbine disk to the turbine shaft and the heat transfer to the inner ring of the turbine axial bearing, ensuring that the bearing temperature is within an acceptable range.

[0037] Therefore, the new turbine shaft insulation structure can achieve good insulation when the engine is running or stopped, reduce the burden of active cooling, always control the bearing temperature within a reasonable range, and increase the service life of the bearing.

[0038] The number of circumferential grooves on the mating surfaces of the annular adapter plate and the turbine disk is limited by the radial width of the mating surfaces. To ensure the effectiveness of the mating positioning, the groove area is generally not larger than 60% of the mating end surface. The groove depth is limited by the axial width of the annular adapter plate of the turbine shaft, and is determined after relevant structural and strength considerations, and is generally not larger than 10% of the axial width.

[0039] The annular adapter plate and the turbine plate are fixed by multiple tension bolts. Due to the presence of the tension bolt holes, the circumferential groove will be discontinuous. Therefore, a petal-shaped depression is added between every two tension bolt holes to ensure the connectivity of the circumferential groove.

[0040] In order to enhance the rotary pumping effect of the petal-shaped depressions, the number of cooling air holes opened in the conical section is consistent with the number of petal-shaped depressions and their angular directions correspond one to one, thereby enhancing the cooling effect at all locations.

[0041] The cooling air holes opened in the cylindrical section are evenly distributed along the circumference, which can ensure that the cooling air enters the inner cavity of the turbine shaft evenly and avoid poor local cooling effect. Under the premise that the strength of the turbine shaft allows and the cooling system meets the requirements, the more the better, and it is best to arrange them in multiple sections along the axial direction.

[0042] The depth of the axial groove opened in the mating surface area of ​​the bearing inner ring is due to the strength limitation of the turbine shaft. Under the premise of meeting the strength requirements, the depth of the axial groove is generally not greater than 10% of the wall thickness of the cylindrical section of the turbine shaft; multiple evenly distributed grooves are intended to reduce the impact on the roundness of the bearing inner ring. When the structural dimensions permit, the total width of the axial grooves is not greater than 50% of the circumference of the cylindrical section.

[0043] The present invention provides an axial groove in the mating surface area of ​​the inner ring of the bearing, and its length is longer than the axial length of the inner ring of the bearing, which is convenient for the design and use of the disassembly tool for the inner ring of the bearing. The matching mode between the inner ring of the bearing and the turbine shaft is generally an interference fit, and the assembly can be completed by heating the inner ring of the bearing or cooling the turbine shaft with liquid nitrogen. However, both heating and cooling will cause the turbine shaft and the inner ring of the bearing to change synchronously during disassembly, so a special disassembly tool is required to disassemble at room temperature. The commonly used disassembly tool is a puller structure, so it is often necessary to process a puller groove structure on the inner ring of the bearing for disassembly. The groove structure designed by the present invention is convenient for the use of the puller structure, and there is no need to add a puller groove to the inner ring. While reducing the bearing processing cost, it also avoids stress concentration in the inner ring groove of the bearing, thereby improving reliability.

[0044] The insulation principle of the new turbine shaft insulation structure is simple and easy to implement. It can achieve a good insulation effect without adding additional parts. At the same time, it is less restricted by structural space and can be widely used on various models.

Claims

1. A turbine shaft heat insulation structure, the turbine shaft comprising a cylindrical section, a conical section and an annular adapter plate, the annular adapter plate being connected to the turbine disk by a plurality of bolts; the cylindrical section is interference fit with the inner ring of the bearing; the cylindrical section is hollow; Features: The mating surfaces of the annular adapter disc and the turbine disc are provided with a plurality of annular grooves concentric with the turbine shaft; The mating surface between the annular adapter disk and the turbine disk is also provided with a plurality of petal-shaped depressions, and the plurality of petal-shaped depressions are symmetrically distributed at equal intervals along the circumference of the annular adapter disk.

2. The turbine shaft heat insulation structure according to claim 1, characterized in that: The petal-shaped depression is located in the annular groove area, and a petal-shaped depression is arranged between every two bolts.

3. The turbine shaft heat insulation structure according to claim 2, characterized in that: The conical section is provided with a plurality of cooling air holes penetrating the inner and outer surfaces of the conical section, and the cooling air holes are evenly spaced along the circumference of the conical section.

4. The turbine shaft heat insulation structure according to claim 3, characterized in that: The number of the cooling holes is the same as the number of the petal-shaped recesses, and the angular directions of the cooling holes correspond to the angular directions of the petal-shaped recesses one by one.

5. The turbine shaft heat insulation structure according to claim 1, characterized in that: The total area of ​​the annular groove does not exceed 60% of the area of ​​the matching surface of the annular adapter disk and the turbine disk; the depth of the annular groove does not exceed 10% of the axial width of the annular adapter disk.

6. The turbine shaft heat insulation structure according to claim 1, characterized in that: The outer surface of the matching area between the cylindrical section and the bearing inner ring is provided with a plurality of axial grooves at equal intervals along the circumference of the cylindrical section.

7. The turbine shaft heat insulation structure according to claim 6, characterized in that: The axial length of the cylindrical segment groove is greater than the axial length of the bearing inner ring.

8. The turbine shaft heat insulation structure according to claim 7, characterized in that: The depth of the axial groove does not exceed 10% of the wall thickness of the cylindrical section of the turbine shaft; the total width of the multiple axial grooves does not exceed 50% of the circumference of the cylindrical section.

9. The turbine shaft heat insulation structure according to claim 1, characterized in that: The non-bearing inner ring matching area of ​​the cylindrical section is provided with a plurality of radial cooling air holes at equal intervals along the circumference of the cylindrical section.

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