Hybrid thrust bearing structure and design method thereof

Abstract

The application relates to a dynamic-static pressure hybrid thrust bearing structure and a design method thereof. The bearing structure comprises a back plate, a plurality of fan-shaped bosses are uniformly distributed on the front surface of the back plate at a certain interval, a gasket and a bottom foil are arranged between two adjacent fan-shaped bosses, a fan-shaped flat foil is arranged on the gasket and the bottom foil, a pressure equalizing groove is arranged on the fan-shaped boss, the pressure equalizing groove is an arc-shaped groove, a gas outlet hole is arranged on the pressure equalizing groove, the gas outlet hole is connected with a gas inlet hole through a gas supply channel, the gas supply channel is located in the back plate, and the gas inlet hole is located on the outer wall of the back plate; an exhaust channel is arranged radially in the back plate, one end of the exhaust channel is an exhaust hole, the exhaust hole is located on the inner wall of the back plate, and a fixed screw hole is arranged on the back surface of the back plate. The dynamic-static pressure hybrid bearing provided by the application is a multi-pave block structure, flexible foils and steps with gas inlet holes are staggered. External high-pressure gas supply through the gas inlet hole can improve the back pressure of bearing work, improve the dynamic pressure effect, avoid the wear of the bearing during start and stop, and thus improve the bearing carrying capacity and rigidity.

Description

Technical Field

[0001] This invention relates to a dynamic-static pressure hybrid thrust bearing structure and its design method. Background Technology

[0002] As a core supporting component of high-speed rotor systems, gas bearings are widely used in aerospace, high-speed turbines, cryogenic technology, air circulation, cryogenic refrigeration, micro gas turbines and other fields, and have very good application prospects.

[0003] Gas bearings are generally classified into hydrostatic gas bearings and hydrodynamic gas bearings.

[0004] Hydrostatic gas bearings utilize an external air source to generate a high-pressure gas film to support the rotor, offering advantages such as high load capacity, long service life, and high rotational accuracy. However, hydrostatic bearings often require an independent high-pressure air supply system, increasing system complexity. Furthermore, hydrostatic bearings consume a large amount of air, resulting in higher costs and poor stability under ultra-high-speed operating conditions.

[0005] Hydrodynamic gas bearings utilize the relative motion of the bearing mating surfaces to compress the lubricating gas within a wedge-shaped space under viscous action, thereby generating high pressure within the clearance. Foil bearings are a typical type of hydrodynamic gas bearing, usually composed of flat foils and an elastic support structure. The structural damping and frictional damping generated by their elastic deformation can effectively dissipate the unstable eddy energy of the bearing rotor system, thus improving the high-speed stability and impact resistance of the bearing rotor system. Furthermore, the elastic surface of foil bearings can reduce the precision requirements for bearing machining and assembly, offering good adaptability and economy; however, hydrodynamic gas bearings have disadvantages such as high frictional torque during start-up and shutdown, insufficient load-bearing capacity, and low stiffness.

[0006] Chinese patent application CN112762094A, entitled "A Dynamic-Static Pressure Mixed Gas Thrust Foil Bearing and a Dynamic-Static Pressure Mixing Device," discloses a dynamic-static pressure mixed thrust gas foil bearing. It features an air inlet hole on the top foil, with an air supply pipe passing through the bottom foil from the bottom plate and connecting to the air inlet hole. However, due to the elastic surface of the foil, the air supply pipe cannot guarantee a consistent air supply.

[0007] Chinese patent application with publication number "CN115929790A" and invention title "A Dynamic-Static Pressure Hybrid Foil Gas Thrust Bearing" provides a dynamic-static pressure hybrid thrust gas foil bearing. It embeds a small orifice throttle device, a lever displacement amplification mechanism, and an air groove in the bearing body. It can effectively improve the bearing capacity by raising the wedge-shaped surface between the foil and the thrust plate through the lever. However, the solution does not specify the location of the air groove that affects the bearing performance. Summary of the Invention

[0008] This invention proposes a hybrid dynamic and static pressure thrust bearing structure, in which flexible foils and stepped sections with air inlets are staggered. The external high-pressure air supply through the air inlets can increase the back pressure of the bearing during operation, enhance the dynamic pressure effect, and avoid wear during bearing start-up and shutdown, thereby improving the bearing's load-bearing capacity and stiffness. At the same time, the flexible foils can provide a certain amount of damping for the bearing, absorb the energy of rotor vortex, improve bearing stability, and reduce air consumption during bearing operation.

[0009] The technical solution of this invention to solve the above problems is: a hybrid dynamic and static pressure thrust bearing structure, which is special in that:

[0010] The bearing includes a back plate, which is a hollow cylindrical structure. On the front side of the back plate, several fan-shaped protrusions are evenly distributed around the circumference. A gasket and a bottom foil are placed between adjacent fan-shaped protrusions. A fan-shaped flat foil is placed on the gasket and bottom foil. Each fan-shaped protrusion has a pressure equalization groove, which is an arc-shaped groove with an air outlet. The air outlet is connected to an air inlet via a supply air channel located inside the back plate, while the air inlet is located on the outer wall of the back plate. An exhaust channel is radially arranged inside the back plate, with one end of the exhaust channel serving as an exhaust port located on the inner wall of the back plate. The exhaust port prevents gas from accumulating internally. The pressure equalization grooves ensure a more uniform pressure distribution in the lubrication gap after the high-pressure gas flows in from the exhaust port, reducing localized excessively high or low pressure, thus improving the bearing's load-bearing capacity and suppressing micro-vibrations. Several fixing threaded holes are evenly arranged on the back side of the back plate. These fixing threaded holes are used to fix the hydrostatic mixed pressure bearing to the rotating machinery housing in use.

[0011] Furthermore, a positioning slit is radially opened between two adjacent fan-shaped protrusions along the back plate, with one end of the fan-shaped flat foil and the bottom foil flush with the positioning slit.

[0012] Furthermore, the fixed ends of the gasket and the bottom foil are directly fixed to the back plate by welding or riveting, and the fixed ends of the fan-shaped flat foil are directly fixed to the gasket by welding or riveting.

[0013] Furthermore, addressing the issue that the location of the vent hole is crucial to the performance of hybrid dynamic-static thrust bearings, this invention proposes a design method for the aforementioned hybrid dynamic-static thrust bearing structure. This method fully considers the geometric parameters of the vent hole, thereby rationally determining its optimal location. In addition, the design optimization method provided by this invention also boasts advantages such as high precision, strong applicability, and the ability to fully leverage the performance of hybrid dynamic-static thrust bearings.

[0014] This invention also proposes a design method for the above-mentioned hydrostatic hybrid thrust bearing structure, which is characterized by including the following steps:

[0015] Step 1): Determine the bearing mechanical parameters based on the material and working fluid.

[0016] Step 2): Input bearing geometry parameters ;

[0017] Step 3): Perform 3D modeling of the bearing based on geometric parameters;

[0018] Step 4): Assume initial lubrication clearance h Numerical calculations were performed to obtain the bearing pressure distribution.

[0019] Step 5): Calculate the bearing performance parameters based on the pressure distribution, change the geometric parameters within a reasonable range, repeat the modeling and calculation process to obtain the optimal bearing geometric parameters, thereby determining the location of the vent.

[0020] Further, step 1) specifically involves: determining the bearing's elastic modulus based on the bearing material and lubricant. E Poisson's ratio μ Hydrodynamic viscosity η ,density ρ .

[0021] Furthermore, in step 5), the performance parameters of the hydrostatic hybrid bearing are determined by six geometric parameters. ,in The inner diameter of the bearing. The outer diameter of the bearing. For the number of bearing pads, For the angle of the dynamic pressure region, This refers to the radial position of the air outlet. The circumferential position of the air outlet; the performance parameters include bearing load capacity, friction torque, stiffness, and damping.

[0022] Furthermore, in step 5), and To determine the bearing size based on the bearing parameters input according to design requirements, the position of the vent hole is determined by the parameters. and The decision, its scope is , , And assuming an initial lubrication gap h =0.01 mm.

[0023] Further, in step 5), the optimal geometric parameters for the final design are set within a defined range as follows: The largest set of parameter values, i.e., the location of the air outlet determined by the above design method.

[0024] Advantages of this invention:

[0025] The hydrostatic-dynamic hybrid bearing proposed in this invention features a multi-bearing structure with flexible foils and stepped sections with air inlets arranged in an alternating pattern. External high-pressure air supply through the air inlets increases the back pressure of the bearing during operation, enhancing the hydrodynamic effect and preventing wear during start-up and shutdown, thereby improving the bearing's load-bearing capacity and stiffness. Simultaneously, the flexible foils provide damping, absorbing the energy of rotor whirl, improving bearing stability, and reducing air consumption during operation. Addressing the crucial role of the air outlet location in the performance of the hydrostatic-dynamic hybrid bearing, the design method provided in this invention fully considers the geometric parameters of the air outlet, thus rationally determining its optimal location. Furthermore, the design optimization method provided in this invention offers advantages such as high precision, strong applicability, and the ability to fully utilize the performance of the hydrostatic-dynamic hybrid thrust bearing. Attached Figure Description

[0026] Figure 1 This is an exploded view of the overall structure of the hydrostatic hybrid thrust bearing provided by the present invention;

[0027] Figure 2 This is a top view of the hydrostatic-dynamic hybrid thrust bearing provided by the present invention;

[0028] Figure 3 This is another angle view of the hydrostatic-dynamic hybrid thrust bearing provided by the present invention;

[0029] Figure 4 This is another angle view of the hydrostatic-dynamic hybrid thrust bearing provided by the present invention;

[0030] Figure 5 yes Figure 4 Enlarged view of point B in the middle;

[0031] Figure 6 This is a schematic diagram of the design method for the hydrostatic hybrid thrust bearing provided by the present invention;

[0032] Figure 7 These are the front view and isometric view of the back plate of the hydrostatic-hydrostatic hybrid thrust bearing provided by this invention;

[0033] Figure 8 yes Figure 7 Enlarged view of point A in the middle;

[0034] Figure 9 This is a schematic diagram of the bearing geometry parameters provided by the present invention.

[0035] In the diagram: 1-flat foil; 2-gasket; 3-bottom foil; 4-back plate; 41-boss; 42-vent; 43-inlet; 44-exhaust hole; 45-positioning slit; 46-fixing threaded hole. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention.

[0037] Example 1

[0038] See Figures 1-5 A hybrid dynamic-static thrust bearing structure includes a back plate 4, which is a hollow cylindrical structure. Several fan-shaped protrusions 41 are evenly distributed circumferentially on the front side of the back plate 4. A gasket 2 and a bottom foil 3 are provided between two adjacent fan-shaped protrusions 41. Fan-shaped flat foils 1 are provided on the gaskets 2 and bottom foils 3, with a gasket 2 and a bottom foil 3 corresponding to each fan-shaped flat foil 1. A pressure equalization groove is provided on the fan-shaped protrusions 41. The pressure equalization groove is an arc-shaped groove with an air outlet 42. The air outlet 42 is connected to an air inlet 43 through a supply air channel located inside the back plate 4, and the air inlet 43 is located on the outer wall of the back plate 4. An exhaust channel is radially penetrating the back plate 4, with one end of the exhaust channel being an exhaust hole 44 located on the inner wall of the back plate 4. Referring to 7, several fixing threaded holes 46 are evenly arranged on the back side of the back plate. The fixing threaded holes 46 are used to fix the hybrid dynamic-static thrust bearing to the rotating machinery housing in use.

[0039] The arc-shaped pressure equalization groove on the boss 41 can make the pressure distribution of the high-pressure gas flowing into the lubrication gap from the outlet 42 more uniform, reduce the situation of excessively high or low local pressure, and improve the bearing's load-bearing capacity and suppress the bearing's micro-vibration.

[0040] See Figure 3 An exhaust channel is provided on the back plate 4 between two adjacent fan-shaped protrusions 41. The exhaust channel is arranged radially from the inner ring to the outer ring inside the back plate, and its function is to prevent gas from accumulating inside.

[0041] Specifically, see 2. Figure 3 , Figure 4 and Figure 5 A positioning slit 45 is radially opened between two adjacent fan-shaped protrusions 41 along the back plate 4. The positioning slit 45 penetrates the back plate 4. One end of the fan-shaped flat foil 1 and the bottom foil 3 is flush with the positioning slit 45. The positioning slit 45 increases the heat dissipation channel inside the bearing and enhances the heat dissipation effect of the bearing.

[0042] Specifically, see 2. Figure 3 and Figure 5 The fixed ends of the gasket 2 and the bottom foil 3 are directly fixed to the back plate 4 by welding or riveting, and the fixed end of the fan-shaped flat foil 1 is directly fixed to the gasket 2 by welding or riveting.

[0043] When the hydrostatic hybrid thrust bearing is in operation, external high-pressure gas flows into the back plate from the inlet 43 and into the lubrication gap between the bearing and the rotor from the outlet 42. This increases the pressure in the gas film gap and enhances the hydrostatic effect, thereby improving the bearing's load-bearing capacity and stiffness and preventing bearing wear during start-up and shutdown. At the same time, the flexible foil structure, including the flat foil 1 and the bottom foil 3, can provide a certain amount of damping for the bearing, absorb the eddy energy during rotor operation, and improve system stability.

[0044] Furthermore, addressing the issue that the location of the vent hole is crucial to the performance of hybrid dynamic-static thrust bearings, this invention proposes a design method for the aforementioned hybrid dynamic-static thrust bearing structure. This method fully considers the geometric parameters of the vent hole, thereby rationally determining its optimal location. In addition, the design optimization method provided by this invention also boasts advantages such as high precision, strong applicability, and the ability to fully leverage the performance of hybrid dynamic-static thrust bearings.

[0045] This invention also proposes a design method for the above-mentioned hydrostatic hybrid thrust bearing structure, see [link to relevant documentation]. Figures 6-9 The process of simplifying a bearing with a periodic structure into a single design model along its circumference involves the following steps:

[0046] Step 1): Determine the bearing mechanical parameters based on the material and working fluid, select the required bearing material and lubricating fluid, and thus determine the bearing's elastic modulus. E Poisson's ratio μ Hydrodynamic viscosity η ,density ρ ;

[0047] Step 2): Input bearing geometry parameters Assume a set of bearing geometric parameters ,in The inner diameter of the bearing. The outer diameter of the bearing. The number of bearing pads refers to the number of basic functional components of a bearing, which is also equivalent to the number of flat foil 1, gasket 2, and bottom foil 3. For the angle of the dynamic pressure region, The radius of the center of the air outlet 42 is... The circumferential angle of the air outlet is 42.

[0048] Step 3): Establish the three-dimensional geometric model and finite element physical calculation model of the bearing in this invention based on the geometric parameters;

[0049] Step 4): Assume initial lubrication clearance h The bearing pressure distribution was obtained by solving the Reynolds equation and performing numerical calculations.

[0050]

[0051] Step 5): Calculate bearing performance parameters (e.g., bearing load capacity) based on pressure distribution. By modifying the geometric parameters within a reasonable range and repeating the modeling and calculation process, the optimal bearing geometric parameters are obtained, thereby determining the location of the vent 42. Bearing performance parameters include bearing load capacity, frictional torque, stiffness, and damping.

[0052] Furthermore, under the hydrodynamic effect, the lubricating gas film exhibits a non-uniform pressure distribution, which varies depending on the number of bearings. and the angle of the dynamic pressure region The bearing geometric parameters range is: , , By controlling the radius of the center of the air outlet 42 and circumferential angle To match the high-pressure zone of the lubricating gas film, the high-pressure zone of the gas film under hydrodynamic effect often appears in the middle section of the fan-shaped area near the outer edge. The reasonable position of the vent 42 should be in the middle section of the bearing near the outer edge, and close to the fixed end of the foil. This can maximize the pressure and effective bearing area of ​​the high-pressure zone, and obtain a set of geometric parameters that optimize the target performance parameters. .

[0053] Specifically, the design parameters and calculated values ​​in this example are as follows:

[0054]

[0055] The above description is merely an embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification and drawings, or direct or indirect applications in other related system fields, are similarly included within the scope of protection of the present invention.

Claims

1. A design method for a hybrid dynamic and static pressure thrust bearing structure, characterized in that, The dynamic and static pressure hybrid thrust bearing structure includes a back plate (4), which is a hollow cylindrical structure. Several fan-shaped bosses (41) are evenly distributed around the front of the back plate (4). A gasket (2) and a bottom foil (3) are provided between two adjacent fan-shaped bosses (41). Fan-shaped flat foils (1) are provided on the gasket (2) and the bottom foil (3). A pressure equalization groove is provided on the fan-shaped bosses (41). The pressure equalization groove is an arc-shaped groove. An air outlet (42) is provided on the pressure equalization groove. The air outlet (42) is connected to the air inlet (43) through a supply air channel. The air supply channel is located inside the back plate (4), and the air inlet (43) is located on the outer wall of the back plate (4); the back plate (4) is provided with an exhaust channel in the radial direction, one end of which is an exhaust hole (44), and the exhaust hole (44) is located on the inner wall of the back plate (4); a number of fixing threaded holes (46) are evenly arranged on the back side of the back plate; a positioning slit (45) is opened radially along the back plate (4) between two adjacent fan-shaped bosses (41), and one end of the fan-shaped flat foil (1) and the bottom foil (3) is flush with the positioning slit (45). The method includes the following steps: Step 1): Determine the bearing mechanical parameters based on the material and working fluid, specifically: determine the bearing elastic modulus based on the bearing material and lubricating fluid. E Poisson's ratio μ Hydrodynamic viscosity η ,density ρ ; Step 2): Input bearing geometry parameters ; Step 3): Perform 3D modeling of the bearing based on geometric parameters; Step 4): Assume an initial lubrication clearance. h Numerical calculations were performed to obtain the bearing pressure distribution. Step 5): Calculate the bearing performance parameters based on the pressure distribution, change the geometric parameters within a reasonable range, repeat the modeling and calculation process to obtain the optimal bearing geometric parameters, thereby determining the location of the vent (42); The bearing performance parameters are determined by six geometric parameters. ,in The inner diameter of the bearing. The outer diameter of the bearing. For the number of bearing pads, For the angle of the dynamic pressure region, The radial position of the vent (42) is shown. The circumferential position of the air outlet (42); the performance parameters include bearing capacity, friction torque, stiffness and damping; In step 5): and To determine the bearing size based on the bearing parameters input according to design requirements, the position of the vent (42) is determined by the parameters. and The decision, its scope is , , And assuming an initial lubrication gap h =0.01 mm; the optimal geometric parameters for the final design are set within the specified range as follows: The position of the air outlet (42) is finally determined by the largest set of parameter values.

2. The design method according to claim 1, characterized in that: The fixed ends of the gasket (2) and the bottom foil (3) are directly fixed to the back plate (4) by welding or riveting, and the fixed end of the fan-shaped flat foil (1) is directly fixed to the gasket (2) by welding or riveting.

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