A tilting pad hydrodynamic bearing

Abstract

A tilting pad dynamic pressure bearing that implements pressure fluid internal feedback support on the pad back relates to the technical field of sliding bearings, and specifically includes a bearing outer ring, a pad and a mounting assembly. An oil collecting groove is arranged on the sliding surface of the pad, and the oil collecting groove collects the pressure lubricating fluid on the sliding surface and feeds it back through the oil hole into the oil cavity arranged on the back of the pad, forming a supporting force for the pad. A deformation structure is arranged in the middle of the pad, which divides the pad into two blocks, and the mounting assembly applies a radial elastic pressing force to the pad. When the bearing is working, under the action of the supporting force of the oil cavity on the back of the pad, the corresponding block of the pad overcomes the radial elastic pressing force and the main shaft load force, and tilts up with the deformation structure as a fulcrum, so that the bearing pad can be tilted, and a convergent gap is formed so that the bearing obtains a good lubrication and load-bearing effect; the back of the pad and the inner surface of the bearing outer ring are fully contacted and supported, which is conducive to the stability of the support; the generated internal feedback lubrication flow can additionally increase the working flow of the bearing, which is of great benefit to the heat dissipation and cooling of the bearing.

Description

Technical Field

[0001] The present invention relates to the technical field of fluid-lubricated dynamic pressure sliding bearings, and in particular to a tilting pad dynamic pressure bearing that implements pressure fluid internal feedback support on the pad back. Background Art

[0002] Tilting pad bearings are generally composed of 3 to 6 arc-shaped pads that can tilt freely on the fulcrum, so they are also called active fulcrum multi-pad support bearings, also called swinging tilting pad bearings. Their pads can swing adaptively with the speed, load and bearing temperature, forming multiple oil films around the shaft neck, and the pressure of each oil film is concentrated towards the center. It has the advantages of large bearing capacity, good vibration resistance, low power consumption and high rotation accuracy. The manufacturing process is relatively simple, the lubrication system is simple, and the maintenance cost is low. Its application range in the industrial field is larger than that of hydrostatic sliding bearings. It is currently widely used in centrifugal compressors, steam turbines and high-speed precision machine tool spindles.

[0003] During operation, the main shaft is mounted on the surface of a hydrodynamic sliding bearing. The hydrodynamic sliding bearing relies on a fluid pressure film formed between two surfaces in relative motion to carry loads. For example, Chinese patent No. ZL200920069501.X discloses a connection between the tilting pad and the bearing seat via a pad pin. This pad pin and the tilting pad form a revolute pair, allowing the tilting pad to swing slightly about the pad pin. This demonstrates that a key feature of a tilting pad hydrodynamic bearing is that the pad located on the inner side of the bearing outer ring can tilt around a pivot point on the pad back during operation. This serves to create an optimal convergence gap between the bearing's hydrodynamic surfaces. Under specific operating parameters, the tilt displacement is unique and stable. The position and structure of the pivot point are key factors influencing the performance of the tilting pad bearing. In recent years, sensor-based online variable-pivot tilting pad bearings have emerged. These are equivalent to using a sensor transmitter to adjust the bearing's tilt. These are also a form of fixed-pivot tilting pad bearings. However, their control robustness is very poor when faced with complex bearing operating conditions. Another example is the Chinese patent ZL201580001447.3, which specifically discloses that each bearing pad can be configured to swing along the circumference and axial direction of the housing, using a pivot as the fulcrum. Besides the aforementioned fulcrum methods, a commonly used spherical steel fixed-pivot tilting pad bearing is a common method. This type of bearing has certain limitations in suppressing oil film oscillations. Furthermore, the spherical fixed fulcrum is a point contact, which can lead to wear and failure after long-term operation, shortening the bearing's service life.

[0004] In summary, because the pads of the existing tilting pad hydrodynamic bearings have a small supporting area and a gap between the pads and the outer ring of the bearing support in order to achieve spatial swing, vibration is easily generated during operation, the load-bearing is unstable, and transportation and installation are inconvenient. Summary of the Invention

[0005] In response to the above-mentioned existing technical problems, the present invention provides a tilting pad dynamic pressure bearing that can suppress vibration and has stable load bearing.

[0006] To achieve the above objectives, the present invention provides the following technical solutions.

[0007] A tilting pad dynamic pressure bearing that implements pressure fluid internal feedback support on the pad back is provided, comprising a bearing outer ring, a plurality of pads and a plurality of mounting components, wherein the plurality of pads are limitedly mounted on the annular inner surface of the bearing outer ring by the plurality of mounting components, the surfaces of the plurality of pads in contact with the main shaft diameter are sliding surfaces, an oil collecting groove is provided on the sliding surface of the pad, the oil collecting groove can collect part of the pressure lubricating fluid on the sliding surface and then feedback it into the oil cavity provided on the back of the pad through the oil hole, thereby forming a supporting force for the pad; a deformation structure is provided in the middle of the pad, which divides the pad into two blocks; the mounting component applies a radial elastic pressing force to the pad; when the bearing is working, under the action of the supporting force of the oil cavity on the back of the pad, the corresponding local block of the pad overcomes the radial elastic pressing force and the main shaft load force, and tilts up with the deformation structure as a fulcrum, thereby realizing the tilting of the bearing pad and forming a convergent gap. The convergent clearance enables the bearing to obtain good lubrication and load-bearing effect; the back of the pad and the inner surface of the bearing outer ring achieve full-surface contact support, which is conducive to support stability; the generated internal feedback lubrication flow can additionally increase the bearing working flow, which is of great benefit to the heat dissipation and cooling of the bearing.

[0008] Preferably, the oil collecting groove, the oil hole and the oil cavity constitute a lubricating fluid pressure feedback structure.

[0009] Preferably, a deformation groove running longitudinally along the axial direction is provided on the back of the tile, the longitudinal section of the deformation groove is T-shaped, and the bottom width of the deformation groove is relatively wide, so that a thin wall is formed between the bottom of the deformation groove and the sliding surface of the tile, and the thin wall becomes the deformation structure of the tile.

[0010] Preferably, the lubricating fluid pressure feedback structure is located at a position on the tile deviating from the deformation groove. The number of pressure feedback structures can be two groups, in which case the two groups of pressure feedback structures are symmetrically arranged relative to the deformation groove; the pressure feedback structure can also be only a single group, in which case the pressure feedback structure is set on a specific side of the deformation groove.

[0011] Preferably, the sliding surfaces of the plurality of pads are collectively enclosed into a conical or cylindrical shape by the constraint of the inner surface of the outer ring.

[0012] Preferably, each set of mounting components includes a limiting plate and a threaded column. The outer ring of the bearing is provided with a threaded hole. The axis of the threaded hole intersects with the axis of the bearing. The threaded column passes through the limiting plate and then into the threaded hole, so that the threaded column presses the limiting plate against the outer ring of the bearing; the tile is provided with a groove, and elastic structures are provided on both sides of the limiting plate. The elastic structure is embedded in the grooves of two adjacent tiles, thereby limiting the tiles in the circumferential and radial directions.

[0013] Preferably, a hollow pipe is provided in the middle of the threaded column, and the hollow pipe is communicated with the bearing oil distribution structure for introducing lubricating fluid.

[0014] Preferably, the back surface of the shoe and the inner surface of the bearing outer ring are tightly fitted spherical surfaces, so that the shoe can also be limited in the axial direction.

[0015] Preferably, the entire tile is made of friction alloy, or the tile adopts a steel body, and a partial surface of the steel body is die-cast or cast and covered with a friction alloy layer.

[0016] Preferably, the lubricating fluid used for the bearing assembly is lubricating oil, water lubricating fluid, gas or oil-gas two-phase lubricating fluid.

[0017] Beneficial effects of the present invention:

[0018] Compared with the prior art, the tilting pad hydrodynamic bearing of the present invention is characterized by the fact that the pressure lubricating fluid during operation of the bearing is fed back into the oil chamber provided on the back of the pad to form a local supporting force. The pad can then partially overcome the radial elastic compressive force and tilt up at the fulcrum formed by the deformation structure, achieving the effect of a tilting pad convergent gap, which complies with the principle of hydrodynamic fluid lubrication. The convergent gap enables the bearing to obtain a good lubrication and load-bearing effect; the back of the pad is in full contact with the inner surface of the bearing outer ring, which is conducive to stable support; the generated internal feedback lubrication flow can further increase the working flow of the bearing, which is of great benefit to the heat dissipation and cooling of the bearing. In the non-operating state, since the mounting assembly applies radial elastic compressive force to the pad, the back of the pad sticks to the inner surface of the bearing outer ring, and there is no space for free displacement between the pad and the outer ring, so that the bearing assembly always remains compact and stable during use, installation and transportation. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a three-dimensional view of the tilting pad hydrodynamic bearing in the embodiment.

[0020] Figure 2 It is a three-dimensional view of the bearing outer ring of the tilting pad dynamic pressure bearing in the embodiment.

[0021] Figure 3 It is a three-dimensional view of the pad of the tilting pad dynamic pressure bearing in the embodiment.

[0022] Figure 4This is another visual perspective view of the pad of the tilting pad hydrodynamic bearing in the embodiment.

[0023] Figure 5 3D diagram of the mounting assembly of the tilting pad hydrodynamic bearing in the embodiment.

[0024] Figure 6 Schematic diagram of the installation of the tilting pad hydrodynamic bearing and the main shaft diameter in the embodiment.

[0025] Figure 7 Diagram of the working principle of the tilting bearing that realizes internal feedback for the bearing pressure fluid.

[0026] Reference numerals include:

[0027] Bearing outer ring 1, threaded hole 11, outer surface 12, inner surface 13;

[0028] Pad 2, sliding surface 21, oil collecting groove 22, feedback oil hole 23, groove 24, T-shaped deformation groove 25, back surface 26, oil cavity 27;

[0029] Mounting assembly 3, elastic structure 31, threaded column 32;

[0030] Spindle 4. DETAILED DESCRIPTION

[0031] The present invention is described in detail below with reference to specific embodiments.

[0032] The tilting pad dynamic pressure bearing of this embodiment is as follows Figure 1 、 Figure 2 、 Figure 3 、 Figure 4 and Figure 6 As shown, it includes a bearing outer ring 1, multiple pads 2, and multiple sets of mounting assemblies 3. The multiple sets of mounting assemblies 3 install multiple pads 2 on the annular inner surface 13 of the bearing outer ring 1. The back surface 26 of the pad 2 and the inner surface 13 of the bearing outer ring 1 are matching spherical surfaces. The centers of the two spheres coincide with the rotation axis of the main shaft 4 on which they are installed. Through precision manufacturing, the two spherical surfaces are completely fitted together when not in operation, and the pads 2 are limited in the axial direction. The outer surface 12 of the bearing outer ring 1 is cylindrical and can be firmly installed in the bearing seat of the peripheral equipment through interference fit. The diameter of the bearing outer ring 1 can be changed from small to large to form a series, but the diameter is larger than the width dimension, and the width-to-diameter ratio is preferably within 0.5. The width dimension of the pad 2 is equal to the width of the bearing outer ring 1, and the two sides are flush, making the overall structure of the bearing more compact.

[0033] In this embodiment, combined with Figure 3As shown, the inner surface of the bearing outer ring 1 is tapered, allowing the sliding surfaces 21 of the multiple pads 2 to collectively form a conical surface, thereby forming a radial dynamic pressure sliding bearing. In practice, the sliding surfaces 21 of the multiple pads 2 can alternatively be collectively formed into a cylindrical surface, thereby forming a radial thrust dynamic pressure sliding bearing. In this embodiment, the pads 2 can be made entirely of a friction alloy, such as brass used in bearings. Alternatively, the bearing body can be made of steel, with a friction alloy layer die-cast or cast onto the sliding surface 21 of the bearing body.

[0034] In this embodiment, combined with Figure 5 As shown, each mounting assembly 3 includes a retaining plate and a threaded post 32 with a T-shaped cross-section. The bearing outer ring 1 is provided with the same number of threaded holes 11 as the number of pads 2. The threaded post 32 passes through the retaining plate and then into the threaded holes 11, so that the head of the threaded post 32 presses the retaining plate against the bearing outer ring 1. Elastic structures 31 are provided on either side of the retaining plate. These structures 31 insert into the grooves 24 at the ends of two adjacent pads 2. This restrains the pads 2 in both the circumferential and radial directions, eliminating free movement between the pads 2 and the bearing outer ring 1. This ensures that the bearing assembly remains compact and stable during use, installation, and transportation, suppressing vibration. However, the elastic structure 32 is capable of elastically deforming in the radial direction when subjected to force. A hollow conduit is provided in the middle of the threaded post 32. The hollow conduit connects to the oil distribution groove in the outer bearing seat hole to evenly distribute the lubricating fluid in the oil distribution groove to each pad 2. The lubricating fluid can be lubricating oil, water lubricant, lubricating gas, or an oil-gas two-phase lubricant. The axis of the hollow pipe and the threaded hole 11 is strictly aligned with the spherical center of the inner surface of the bearing outer ring 1, so that a better mechanical effect is achieved when the threaded column 32 fixes the tile 2.

[0035] Combine Figure 4 and Figure 5 As shown, the back of the pad 2 is provided with a T-shaped deformation groove 25 extending longitudinally along the axial direction. As a deformable structure, the T-shaped deformation groove 25 has a thin upper edge and a wide width. Under the action of lubricating oil pressure, it can deform on the micrometer scale, allowing the pad 2 to tilt halfway, using this deformation structure as a fulcrum. In practice, the deformation groove 25 can be modified to other shapes, such as a square, but the T-shape of this embodiment is preferred, as it maintains a certain strength of the pad 2 while facilitating deformation and tilting of the pad 2.

[0036] The sliding surface 21 of the pad 2 is provided with two strip-shaped oil-collecting grooves 22, symmetrically arranged relative to the T-shaped deformation groove 25. The grooves 22 communicate with a rectangular oil cavity 27 on the back of the pad 2 via a feedback oil hole 23. The size, depth, and location of the grooves 22 and cavity 27 on the pad 2 are determined through calculation and analysis. The resulting bearing assembly, with its twin grooves 22 and cavity 27, is suitable for bidirectional rotation of the spindle 4. In practice, the grooves 22 and cavity 27 can also be arranged singly relative to the T-shaped deformation groove 25, i.e., one half of the pad 2 has a pressure feedback structure while the other half does not. The resulting bearing assembly is suitable for unidirectional rotation of the spindle, with the shaft surface sliding along the direction from the absence of the pressure feedback structure to the presence of the pressure feedback structure.

[0037] Combine Figure 6 As shown, when in use, the sliding surface 21 of the pad 2 is coaxial with and in contact with the surface of the main shaft 4. When the main shaft 4 rotates, oil film pressure is generated on the sliding surface 21 of the pad 2 according to the fluid lubrication theory, thereby separating the contact surface of the pad 2 and the main shaft 4. The oil film pressure becomes the radial load capacity or radial thrust load capacity of the bearing. Figure 7 As shown, the main shaft 4 rotates in the direction of arrow N, bringing the lubricating fluid into the bearing inlet clearance, forming a flow rate Q. In the process of flowing along the sliding surface 21, this part of the flow is squeezed into an internal pressure oil film, thereby separating the axial diameter surface of the main shaft 4 from the surface of the tile 2 to meet the bearing load-bearing working needs. The internal pressure distribution of the entire sliding surface 21 changes rapidly from small to large. Since there are oil collection grooves 22 distributed on the sliding surface 21 of the tile 2, the oil collection grooves 22 can collect part of the pressure lubricating oil Q1 on the sliding surface 21, and feed the pressure oil Q1 back into the oil chamber 27 set on the back of the tile 2 through the feedback oil hole 23, forming a supporting force for the tile 2, and the remaining flow rate Q2 flows out from the bearing outlet clearance. Since a T-shaped deformation groove 25 is opened in the middle of the back of the tile 2, the upper edge of the T-shaped deformation groove 25 is thinner, as shown in FIG. Figure 7As shown, the entire pad 2 is divided into two parts by the vertical dotted line. The right half of the pad 2 is pressed tightly against the inner surface of the bearing outer ring 1 by the elastic structure 32. At this time, the rotation of the main shaft 4 drives the lubricating fluid into the left oil collecting groove 22. The supporting force of the right oil chamber 27 overcomes the force of the elastic structure 32, causing the left elastic structure 32 to elastically deform radially. This in turn causes the left half of the pad 2 to tilt and tilt about 0.7h0 around the upper edge of the T-shaped deformation groove 25 toward the main shaft 4. As a result, the sliding surface 21 of the pad 2 at this location forms a converging oil wedge with an inlet gap of approximately 1h0 and an outlet gap of approximately 0.3h0, which conforms to the lubrication principle of a hydrodynamic bearing. Because the pressure at the right inlet is still relatively low, the supporting force fed back from the oil collecting groove 22 and oil chamber 27 is insufficient to displace this portion of the pad 2. Therefore, the right half of the pad near the bearing inlet gap is pressed tightly against the inner surface of the bearing outer ring. After use, the spindle 4 stops moving, and under the action of the elastic structure 3, the left side of the shoe 2 returns to its original shape, and the entire back side is again attached to the inner surface of the bearing outer ring 1.

[0038] Compared with the prior art, the tilting pad hydrodynamic bearing of this embodiment has the following advantages:

[0039] (1) Without changing the bearing lubrication system or increasing operating costs, the pad 2 can be tilted according to the working state of the bearing. The fluid bearing structure is simple, the load is stable, and the damping characteristics are good, achieving the purpose of reducing bearing friction power consumption, lowering temperature rise, and suppressing vibration, thereby better adapting to the working requirements of different bearing working conditions. It is suitable for large-scale high-speed rotating machinery such as steam turbines, and is even more suitable for high-speed precision machine tool spindles.

[0040] (2) The bearing assembly has compact radial and axial dimensions, a simple structure, a small number of parts, and a stable structure in any state.

[0041] (3) During operation, half of the back surface of the tile 2 always maintains full contact with the inner surface of the bearing outer ring 1, and there is no mechanical friction and wear.

[0042] (4) During operation, the pressure fluid floats the other half of the tile 2, which satisfies the theoretical conditions of fluid dynamic lubrication very well, and the static pressure oil cavity on the tile back plays a damping and vibration reduction role.

[0043] (5) The flow rate of the fluid involved in lubrication increases, and the fluid plays a role in heat dissipation, which is greatly helpful in reducing the temperature rise of the bearing. It is particularly suitable for high-speed precision technical equipment.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A tilting pad hydrodynamic bearing, comprising a bearing outer ring, a plurality of pads and a plurality of mounting assemblies, wherein the plurality of pads are limitedly mounted on the annular inner surface of the bearing outer ring by the plurality of mounting assemblies, and the surfaces of the plurality of pads in contact with the main shaft diameter are sliding surfaces, wherein: An oil collecting groove is arranged on the sliding surface of the tile, which can collect part of the pressure lubricating fluid on the sliding surface and then feed it back into the oil cavity arranged on the back of the tile through the oil hole to form a supporting force for the tile; A deformation structure is arranged in the middle of the tile, dividing the tile into two blocks; the installation assembly applies radial elastic pressing force to the tile; When the bearing is working, under the action of the supporting force of the oil cavity on the back of the pad, the corresponding local block of the pad overcomes the radial elastic pressing force and the main shaft load force, and tilts up with the deformation structure as a fulcrum, so that the bearing pad can be tilted and a convergent gap is formed; The back of the tile is provided with a deformation groove running longitudinally in the axial direction. The longitudinal section of the deformation groove is T-shaped, and the bottom width of the deformation groove is relatively wide, so that a thin wall is formed between the bottom of the deformation groove and the sliding surface of the tile, and the thin wall becomes the deformation structure of the tile; Each set of mounting components includes a limit plate and a threaded column. The outer ring of the bearing is provided with a threaded hole. The axis of the threaded hole intersects with the axis of the bearing. The threaded column passes through the limit plate and then enters the threaded hole, so that the threaded column presses the limit plate against the outer ring of the bearing; the tile is provided with a groove, and elastic structures are provided on both sides of the limit plate. The elastic structure is embedded in the grooves of two adjacent tiles, so as to limit the tile in the circumferential and radial directions.

2. The tilting pad hydrodynamic bearing according to claim 1, characterized in that: The oil collecting groove, the oil hole and the oil chamber constitute a lubricating fluid pressure feedback structure.

3. The tilting pad dynamic pressure bearing according to claim 2, characterized in that: The lubricating fluid pressure feedback structure is located at a position on the tile deviating from the deformation groove. There are two groups of pressure feedback structures, and the two groups of pressure feedback structures are symmetrically arranged relative to the deformation groove; or there is only a single group of pressure feedback structures, and the pressure feedback structure is set on one side of the deformation groove.

4. The tilting pad hydrodynamic bearing according to claim 1, characterized in that: The plurality of pads are constrained by the inner surface of the outer ring to envelop the sliding surfaces into a conical or cylindrical shape.

5. The tilting pad hydrodynamic bearing according to claim 1, characterized in that: A hollow pipe is arranged in the middle of the threaded column, and the hollow pipe is communicated with the bearing oil distribution structure for introducing lubricating fluid.

6. The tilting pad hydrodynamic bearing according to claim 1, characterized in that: The back surface of the tile and the inner surface of the bearing outer ring are tightly fitted spherical surfaces, so that the tile can also be limited in the axial direction.

7. The tilting pad hydrodynamic bearing according to claim 1, characterized in that: The whole tile is made of friction alloy, or the tile adopts a steel body, and a friction alloy layer is die-cast or cast on a local surface of the steel body.

8. The tilting pad hydrodynamic bearing according to claim 1, characterized in that: The lubricating fluid used for the bearing assembly is lubricating oil, water lubricating fluid, gas or oil-gas two-phase lubricating fluid.

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