A rotor support structure with simultaneous axial and radial stiffness control

Abstract

The application discloses a rotor supporting structure with simultaneously adjustable axial and radial stiffness, which comprises an axial weak stiffness squirrel cage, a limiting ring and a fastening screw. The axial weak stiffness squirrel cage is in a folded-back structure form, and a bearing mounting seat is arranged on the inner mounting edge of the axial weak stiffness squirrel cage; the bearing mounting seat and the limiting ring form a bearing mounting cavity, thereby achieving axial fixation of the outer ring of the bearing; and a spoke is arranged on the outer mounting edge of the axial weak stiffness squirrel cage, so as to provide smaller axial stiffness. The fastening screw is used for connecting the axial weak stiffness squirrel cage and the limiting ring. The supporting structure has the advantages that smaller radial stiffness can be achieved to reduce the critical speed of the rotor system and reduce rotor vibration, smaller axial stiffness can be achieved to ensure that the rotor system can freely expand and shrink under the action of temperature load, and the supporting structure has a large adjustable range of axial and radial stiffness.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of rotor system supporting structure, and particularly relates to a rotor supporting structure with simultaneously adjustable axial and radial stiffness. BACKGROUND

[0002] With the development of technology, the working speed of modern high-speed rotating machinery is getting higher and higher, and can often reach above the first-order or even the second-order critical speed. For such a rotor, since it will produce a large vibration when approaching or passing through the critical speed, affecting the safe operation of the rotor, appropriate measures must be taken to make the critical speed of the rotor as far as possible from the working speed range. For example, the way of adding elastic support is often used on aero-engines to adjust the critical speed of the rotor, thereby reducing the rotor vibration.

[0003] The commonly used elastic support structures in the industry can be divided into cage bar type elastic support and elastic ring type elastic support, and the cage bar type elastic support can be further divided into squirrel cage type elastic support and pull rod type elastic support. The traditional elastic support structures, such as the squirrel cage elastic support structure disclosed in “CN 102425639 A”, “CN 109026207 B” and “CN 108691893 B”, are all rigidly connected with the casing or the supporting frame through a flange installation form. Although the radial stiffness of such a support structure can be adjusted in a large range by changing the length or width of the cage bar and other size parameters, its axial stiffness is always maintained at a very high level and cannot be adjusted according to actual needs.

[0004] For a rotor system with a large temperature difference in working environment, the use of traditional high-axial-stiffness squirrel cage elastic support will limit the thermal expansion and contraction of the rotor in the axial direction, causing certain thermal stress of the rotor system and thus generating certain axial load. When the axial load is too large, it is easy to cause the buckling instability of the squirrel cage bar, and in severe cases, it can even cause the failure of the squirrel cage support and cause a major accident. SUMMARY

[0005] To solve the above technical problems, the present application provides a rotor supporting structure with simultaneously adjustable axial and radial stiffness. The supporting structure can achieve a smaller radial stiffness to reduce the critical speed of the rotor and reduce the rotor vibration, and can also achieve a smaller axial stiffness to ensure that the rotor can freely expand and contract under the action of thermal load. At the same time, the supporting structure has a large adjustment range of axial and radial stiffness.

[0006] To achieve the above purpose, the technical solution adopted by the present application is as follows:

[0007] The rotor support structure with simultaneously adjustable axial and radial stiffness comprises an axial weak stiffness squirrel cage, a limiting ring and a fastening screw. The axial weak stiffness squirrel cage is used to support the bearing, providing the required radial stiffness and axial stiffness of the rotor system, and the radial stiffness and axial stiffness thereof are adjustable. The limiting ring is used to limit the radial deformation of the axial weak stiffness squirrel cage, avoiding the damage of the squirrel cage caused by the direct action of excessive radial load on the squirrel cage; in addition, the limiting ring and the inner mounting edge of the axial weak stiffness squirrel cage form a bearing mounting cavity, realizing the axial fixation of the bearing outer ring. The fastening screw is used to connect the axial weak stiffness squirrel cage and the limiting ring.

[0008] The rotor support structure, the axial weak stiffness squirrel cage is in the form of a foldback squirrel cage structure, comprising an inner mounting edge, an outer mounting edge, an inner cage bar and an outer cage bar. The inner mounting edge comprises a bearing mounting seat for placing a bearing and a screw hole for fixing a limiting ring. The outer mounting edge comprises an outer ring, an inner ring, a spoke connecting the inner and outer rings and a flange hole for mounting the axial weak stiffness squirrel cage. The inner cage bar and the outer cage bar are both approximately rectangular cross-section cage bars, and both have similar size parameters.

[0009] The rotor support structure, the limiting ring end face is circumferentially uniformly distributed with a limiting ring flange hole for mounting the limiting ring.

[0010] The rotor support structure, the fastening screw connects the axial weak stiffness squirrel cage and the limiting ring into a whole through threads.

[0011] Further, the axial dimension of the bearing mounting seat on the inner mounting edge of the axial weak stiffness squirrel cage is the same as the bearing width, and the inner side is provided with a bearing outer ring retainer for bearing mounting positioning and limiting the axial displacement of the bearing, and the outer side is not provided with a retainer, facilitating the loading of the bearing.

[0012] Further, the inner mounting edge of the axial weak stiffness squirrel cage has a certain radial thickness, and a circle of screw holes is opened thereon.

[0013] Further, the screw holes on the inner mounting edge of the axial weak stiffness squirrel cage are uniformly distributed circumferentially.

[0014] Further, the outer ring on the outer mounting edge of the axial weak stiffness squirrel cage is in axial contact with the support frame to transmit axial load.

[0015] Further, the inner ring on the outer mounting edge of the axial weak stiffness squirrel cage is in radial contact with the support frame to transmit radial load.

[0016] Further, the thickness of the spoke on the outer mounting edge of the axial weak stiffness squirrel cage is smaller than the thickness of the outer ring, and the spoke is provided with a rounded corner at both ends.

[0017] Further, the flange holes on the outer mounting edge of the axial weak stiffness squirrel cage are arranged two between adjacent spokes.

[0018] Further, the inner and outer cage bars of the axial weak stiffness squirrel cage are uniformly distributed in the circumferential direction.

[0019] Further, soft rubber can be filled between the inner and outer cage bars of the axial weak stiffness squirrel cage to obtain greater supporting damping.

[0020] Further, the number, length, width, thickness, and roundness of the spokes on the outer mounting edge of the axial weak stiffness squirrel cage can be changed to change the axial stiffness of the axial weak stiffness squirrel cage.

[0021] Further, the number, length, width, thickness, and roundness of the inner and outer cage bars of the axial weak stiffness squirrel cage can be changed to change the radial stiffness of the axial weak stiffness squirrel cage.

[0022] Further, the axial weak stiffness squirrel cage and the limiting ring are made of spring steel or stainless steel.

[0023] Further, the fastening screw is an internal hexagonal screw.

[0024] After the above technical solutions are adopted, the present application has the following advantages:

[0025] (1) The rotor supporting structure provided by the present application can simultaneously control the axial and radial stiffness, can provide smaller radial supporting stiffness to adjust the critical speed of the rotor system and suppress rotor vibration, and can provide smaller axial stiffness to ensure that the rotor shaft can freely expand and contract in the axial direction under the action of temperature load, thereby having good temperature compensation.

[0026] (2) The rotor supporting structure provided by the present application can simultaneously control the axial and radial stiffness, the axial stiffness of which can be adjusted by adjusting the number, length, width, thickness, and roundness of the spokes on the outer mounting edge of the axial weak stiffness squirrel cage, and the radial stiffness of which can be adjusted by adjusting the number, length, width, thickness, and roundness of the inner and outer cage bars of the axial weak stiffness squirrel cage. Since the modification space of the structure parameters of the spokes and the inner and outer cage bars is large, the supporting structure has a large axial and radial stiffness adjustment range.

[0027] (3) The rotor supporting structure provided by the present application can simultaneously control the axial and radial stiffness, the inner mounting edge of the axial weak stiffness squirrel cage and the limiting ring together form a bearing mounting cavity, and can realize bidirectional fixation of the outer ring of the bearing. When the inner ring of the bearing is also bidirectionally fixed on the shaft, the supporting structure can transmit bidirectional axial load on the rotor shaft.

[0028] (4) The rotor supporting structure with simultaneously controllable axial and radial stiffness provided by the application can limit the radial deformation of the supporting structure through the limiting ring, so as to avoid damage of the supporting structure when it bears excessive load. Meanwhile, soft rubber can be filled between the inner and outer cage bars of the supporting structure, so as to increase the supporting damping without increasing the supporting stiffness, and improve the vibration suppression effect of the supporting structure. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 is a three-dimensional structure schematic diagram of the application;

[0030] Figure 2 is a sectional view of the application;

[0031] Figure 3 is a three-dimensional schematic diagram of the axial weak stiffness squirrel cage of the application;

[0032] Figure 4 is a three-dimensional schematic diagram of the limiting ring of the application;

[0033] Figure 5 is a detail view of the spoke of the outer mounting edge of the axial weak stiffness squirrel cage of the application;

[0034] Figure 6 is an assembly schematic diagram of the supporting structure, rotor, bearing and the like of the application;

[0035] In the figure, 1-axial weak stiffness squirrel cage; 2-limiting ring; 3-fastening screw; 4-supporting frame; 5-rotor; 6-bearing; 7-bearing pre-tightening nut; 11-axial weak stiffness squirrel cage inner mounting edge; 111-bearing mounting seat; 112-screw hole; 12-axial weak stiffness squirrel cage outer mounting edge; 121-outer ring; 122-inner ring; 123-spoke; 124-outer mounting edge flange hole; 13-inner cage bar; 14-outer cage bar; 21-limiting ring flange hole. DETAILED DESCRIPTION

[0036] The present disclosure will be described in further detail below in conjunction with the accompanying drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the relevant content of the present disclosure, and are not a limitation on the present disclosure. In addition, it should be noted that only parts related to the present disclosure are shown in the drawings for ease of description.

[0037] Reference Figures 1-6 The rotor supporting structure with simultaneously controllable axial and radial stiffness provided by the application includes an axial weak stiffness squirrel cage 1, a limiting ring 2 and a fastening screw 3.

[0038] The axial weak stiffness squirrel cage 1 is a foldback squirrel cage structure, comprising an axial weak stiffness squirrel cage inner mounting edge 11, an axial weak stiffness squirrel cage outer mounting edge 12, an inner cage bar 13 and an outer cage bar 14. The axial weak stiffness squirrel cage 1 is used to support the bearing 6, and provides the required radial stiffness and axial stiffness for the rotor 5. The advantage is that the radial stiffness and axial stiffness can be adjusted in a wide range, and the foldback structure does not require a large axial space.

[0039] The axial weak stiffness squirrel cage inner mounting edge 11 is in a cylindrical form, comprising a bearing mounting seat 111 and a screw hole 112. The axial weak stiffness squirrel cage inner mounting edge 11 is connected with the inner cage bar 13, and has a certain radial thickness to ensure that the screw hole 112 is opened on the outer end surface of the axial weak stiffness squirrel cage inner mounting edge 11; and has a certain axial length to form the bearing mounting seat 111 to accommodate the bearing 6. The inner side of the bearing mounting seat 111 is provided with a ring structure, thereby forming an outer ring retainer of the bearing 6, which plays an axial positioning and axial constraint role on the bearing 6.

[0040] The axial weak stiffness squirrel cage outer mounting edge 12 comprises an outer ring 121, an inner ring 122, a spoke 123 for connecting the inner and outer rings, and an outer mounting edge flange hole 124. In operation, the axial weak stiffness squirrel cage 1 is mounted on the support frame 4 through the outer ring 121 and the outer mounting edge flange hole 124, and the outer ring 121 is in axial contact with the support frame 4 to transmit the axial force on the axial weak stiffness squirrel cage 1. The inner ring 122 is connected with the outer cage bar 14, and has a certain axial length to form a larger radial force bearing surface. In operation, the inner ring 122 is in radial contact with the mounting hole on the support frame 4 to transmit the radial force on the axial weak stiffness squirrel cage 1. The spoke 123 is a key structure for forming axial weakness, and has a very small thickness, which can be 1 / 3 of the thickness of the outer ring 121. The two ends of the spoke 123 have round corners to improve the stress concentration at the connection between the spoke 123 and the outer ring 121 and the inner ring 122. The spoke 123 is located on the outer side of the axial weak stiffness squirrel cage outer mounting edge 12, that is, the spoke 123 is not in axial contact with the support frame 4 in operation, so that the axial weak stiffness squirrel cage 1 can slide along the axial direction of the rotor 5 under the action of temperature load.

[0041] The inner cage bar 13 and the outer cage bar 14 are composed of grooves milled on the inner and outer cylindrical walls, and have a cross section in the shape of a rectangular section. The two ends of the inner cage bar 13 and the outer cage bar 14 are also chamfered to improve the stress concentration at the end of the cage bar. In order to improve the damping effect of the support structure of the present application in operation, soft rubber can be filled between the inner cage bar 13 and the outer cage bar 14, thereby greatly improving the damping of the support structure of the present application without affecting the radial support stiffness of the axial weak stiffness squirrel cage 1, and enhancing the vibration suppression effect.

[0042] The limiting ring 2 is mounted on the axial weak stiffness squirrel cage inner mounting edge 11 by the fastening screw 3, and both of them form a mounting cavity of the bearing 6, which can realize the axial fixation of the outer ring of the bearing 6. Normally, there is a certain limiting gap between the outer cylindrical surface of the limiting ring 2 and the inner cylindrical surface of the inner ring 122 on the axial weak stiffness squirrel cage outer mounting edge 12. When the radial load borne by the axial weak stiffness squirrel cage 1 is too large, the limiting gap will be consumed, and the radial force is directly transmitted from the axial weak stiffness squirrel cage inner mounting edge 11 to the axial weak stiffness squirrel cage outer mounting edge 12 through the limiting ring 2, which plays a limiting protection role on the axial weak stiffness squirrel cage 1. The end surface of the limiting ring 2 is uniformly distributed with a plurality of limiting ring flange holes 21.

[0043] The fastening screw 3 is used to connect the axial weak stiffness squirrel cage 1 and the limiting ring 2 into a whole after the bearing 6 is installed on the bearing mounting seat 111 of the axial weak stiffness squirrel cage inner mounting edge 11. In order to facilitate disassembly and occupy smaller space, the fastening screw 3 can be selected as an internal hexagonal screw structure.

[0044] Referring to Figure 6 When the support structure of the present application is assembled, the bearing 6 is first placed in the bearing mounting seat 111 of the axial weak stiffness squirrel cage 1, and then the outer ring of the bearing 6 is fixed by the limiting ring 2 and the fastening screw 3 to form a whole structure; then the whole structure is installed on the rotor 5, and the inner ring of the bearing 6 is fixed by the bearing pre-tightening nut 7; finally, it is placed in the mounting hole of the support frame 4, and is installed on the support frame 4 through the axial weak stiffness squirrel cage outer mounting edge 12.

[0045] When the radial stiffness of the support structure of the present application is adjusted, the number of the inner cage bars 13 and the outer cage bars 14 of the axial weak stiffness squirrel cage 1 is changed first, and then the structural parameters such as the length, width, thickness and round angle size of the inner cage bars 13 and the outer cage bars 14 are adjusted to realize the structural optimization of the axial weak stiffness squirrel cage 1 and the fine adjustment of the radial support stiffness. Similarly, when the axial stiffness of the support structure of the present application is adjusted, the number of the spokes 123 on the axial weak stiffness squirrel cage outer mounting edge 12 is changed first, and then the structural parameters such as the length, width, thickness and round angle size of the spokes 123 are adjusted to realize the fine adjustment of the axial support stiffness. Since the adjustable parameters of the inner cage bars 13, the outer cage bars 14 and the spokes 123 are many and have a wide range, the support structure of the present application has a large adjustment range of radial stiffness and axial stiffness.

[0046] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and any changes, modifications or replacements within the technical range disclosed by the present application can be easily thought by those skilled in the art, which should be covered within the protection scope of the present application.

Claims

1. A rotor support structure in which axial and radial stiffnesses are simultaneously controllable, characterized by, The rotor support structure comprises an axial weak stiffness squirrel cage, a limiting ring and a fastening screw; The axial weak stiffness squirrel cage is in a folded-back structure form, comprising an inner mounting edge, an outer mounting edge, inner cage bars and outer cage bars; The limiting ring is mounted on the axial weak stiffness squirrel cage, and the end faces are uniformly provided with a plurality of limiting ring flange holes; The fastening screw connects the axial weak stiffness squirrel cage and the limiting ring together to form an integral structure; The outer mounting edge of the axial weak stiffness squirrel cage comprises an outer ring, an inner ring, spokes connecting the inner and outer rings and outer mounting edge flange holes; The outer ring of the outer mounting edge of the axial weak stiffness squirrel cage is in axial contact with the support frame, the inner ring is in radial contact with the support frame, the spokes are provided with rounded corners at both ends, the thickness of the spokes is less than the thickness of the outer ring, the spokes are uniformly distributed in the circumferential direction, and two outer mounting edge flange holes are arranged between adjacent spokes; The limiting ring and the inner mounting edge of the axial weak stiffness squirrel cage form a bearing mounting cavity, and the limiting ring and the outer mounting edge of the axial weak stiffness squirrel cage have a radial limiting gap.

2. The rotor support structure with simultaneously controllable axial and radial stiffness according to claim 1, characterized in that, The inner mounting edge of the axial weak stiffness squirrel cage is in a cylindrical structure form, the inner cylindrical surface forms a bearing mounting seat, the outer cylindrical surface is in contact with the limiting ring, the inner end face has a protruding edge to form a bearing outer ring retainer, and the outer end face is provided with a plurality of uniformly distributed screw holes.

3. The rotor support structure with simultaneously controllable axial and radial stiffness according to claim 1, characterized in that, The inner and outer cage bars of the axial weak stiffness squirrel cage are in approximately rectangular cross sections, the two ends of the cage bars are provided with rounded corners, the inner cage bars are connected to the inner mounting edge of the axial weak stiffness squirrel cage, and the outer cage bars are connected to the outer mounting edge of the axial weak stiffness squirrel cage.

4. The rotor support structure with simultaneously controllable axial and radial stiffness according to claim 1, characterized in that, The fastening screw is an inner hexagonal screw.

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