CN106763198B

CN106763198B - Tilting pad thrust bearing with complex sliding surface

Info

Publication number: CN106763198B
Application number: CN201710140101.2A
Authority: CN
Inventors: 刘莹; 宋智翔; 郭飞; 刘向锋; 王玉明
Original assignee: Tsinghua University
Current assignee: Tsinghua University
Priority date: 2017-03-10
Filing date: 2017-03-10
Publication date: 2022-07-01
Anticipated expiration: 2037-03-10
Also published as: CN106763198A

Abstract

The invention provides a tilting pad thrust bearing with a complex sliding surface, which comprises a plurality of pads, wherein the upper surface of each pad is divided into two areas: a region I and the rest region II close to the inlet region, wherein the region I is subjected to surface treatment to form a hydrophobic surface, so that the shear stress is lower, and interface slippage is easy to occur; the area II is subjected to surface treatment to form a hydrophilic surface, so that the area II has higher ultimate shear stress and is not easy to generate interface slippage; after the pressure center change and the tilting characteristic of the pad caused by the interface effect are considered, the radial and circumferential distribution range of the area I is obtained through optimization, after a lubricating medium flows into the area II from the area I, an extra pressure peak can be generated due to the continuity of medium flowing, so that the bearing capacity of the tilting pad thrust bearing is increased, the fluid shearing viscous force in the area I is reduced, so that the friction torque of the tilting pad thrust bearing is reduced, and the problem that the hydrophobic component in the area I is not wear-resistant is solved through the step design of different areas.

Description

Tilting pad thrust bearing with complex sliding surface

Technical Field

The invention belongs to the technical field of bearings, and particularly relates to a tilting pad thrust bearing with a complex sliding surface.

Background

The performance of the thrust bearing, which serves as a basic and critical component in a mechanical system, directly determines the life and reliability of the entire mechanical system. With the gradual popularization of aqueous medium lubrication, the large-size water-lubricated bearing has the characteristics of small film thickness and high linear velocity, and the corresponding shear rate is very high, so that interface slippage can occur between solid-liquid interfaces, particularly on a hydrophobic surface.

In the previous research on the interface slippage, the interface slippage is firstly applied by Spikes in a thrust sliding bearing to reduce the friction torque of the bearing, and later learners apply the interface slippage in a concentric plain bearing and a parallel plate thrust bearing to improve the bearing capacity and reduce the friction torque at the same time.

In the currently granted and published patent, the patent thrust bearing using interface sliding technology (application number: 200810025059.0 publication number CN100545469C) discloses a novel thrust bearing using interface sliding characteristics and composed of flat plates parallel to each other, which realizes a certain bearing capacity and has better antifriction and wear-resistant characteristics; the patent concentric radial sliding bearing formed by using interface sliding (application No. 201510203567.3 publication No. CN104791381A) discloses a concentric radial bearing using interface sliding characteristic, and the bearing has certain bearing capacity and antifriction characteristic; however, the above-disclosed bearing design using interfacial sliding only focuses on the reduction of the bearing capacity and the friction after the interfacial sliding, but does not focus on the pressure center shift caused by the interfacial sliding, so the design cannot be applied to the tilting pad thrust bearing, and the same design parameters may cause the tilting pad thrust bearing to fail.

Due to the defects in the prior art, no complex interface sliding bearing design for the tilting pad thrust bearing exists at present.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention aims to provide a tilting pad thrust bearing with a complex sliding surface aiming at the tilting pad tilting characteristic of the tilting pad thrust bearing, which can improve the bearing capacity of the tilting pad thrust bearing and reduce friction.

In order to achieve the purpose, the invention adopts the technical scheme that:

a complex sliding surface tilting pad thrust bearing comprising a plurality of pads, the upper surface of said pads being divided into two regions: the area I and the rest area II are close to the inlet area, wherein the area I is subjected to surface treatment to form a hydrophobic surface, so that the lower ultimate shear stress is realized, and interface slippage is easy to occur; the area II is subjected to surface treatment to form a hydrophilic surface, so that the shear stress is higher, and interface slippage is not easy to occur.

The height of the area I is lower than that of the area II, the height difference is determined according to the working condition parameters of the actual operation of the bearing and is in the same order of magnitude and in direct proportion to the minimum liquid film thickness of the thrust bearing in the operation process, so that the hydrophobic surface in the area I is protected from being abraded in the starting and stopping processes.

The circumferential extent of the region I is no more than 75% of the total pad wrap angle, taking into account changes in the centre of pressure due to interfacial slippage, which would otherwise cause failure of the bearing due to the pad being tiltable.

Compared with the prior art, the invention has the beneficial effects that:

(1) the tilting pad thrust bearing utilizes the interface slip effect to carry out complex slip surface design, and can simultaneously realize high bearing capacity and low friction torque of the tilting pad thrust bearing.

(2) The change of the pressure center caused by the interface slip effect is considered in the design, so that the failure of the design scheme in the tilting pad thrust bearing is avoided.

(3) The step design of partial pads is utilized to avoid the abrasion to the hydrophobic surface in the starting and stopping process, so that the optimization effect of the bearing is more durable.

Drawings

FIG. 1 is a schematic view of the thrust bearing pad interfacial slip surface design of the present invention.

FIG. 2 is a schematic view of the thrust bearing pad surface height design of the present invention.

FIG. 3 is a schematic diagram of the pressure distribution before optimization in example 1 of the present invention.

FIG. 4 is a schematic view of the pressure distribution after the interface slip optimization in example 1 of the present invention.

Detailed Description

The embodiments of the present invention will be described in detail below with reference to the drawings and examples.

Example 1

In the embodiment, the optimized thrust bearing has the outer diameter of 800mm, the inner diameter of 400mm, the wrap angle of 40 degrees, the radial deflection coefficient of 0.524, the circumferential deflection coefficient of 0.609, the normal working rotating speed of 1500rpm and the average working pressure of 0.544 MPa.

As shown in fig. 1, the upper surface of the pad is divided into two regions: the area I and the rest area II are close to the inlet area, wherein the area I is subjected to surface treatment to form a hydrophobic surface, so that the lower ultimate shear stress is realized, and interface slippage is easy to occur; the area II is subjected to surface treatment to form a hydrophilic surface, so that the ultimate shear stress is high, and interface slippage is not easy to occur.

As shown in fig. 2, the height of zone I is lower than the height of zone II, which in this embodiment is 40 μm lower, to protect the hydrophobic surface in zone I from abrasion caused by the start-up and stop process.

In this example, the ultimate shear stress after surface treatment of the region I was 0.4Pa, the slip length was 100 μm, the ultimate shear stress after surface treatment of the region II was 1MPa, and the slip length was 0.

In the embodiment, the area I accounts for 75% of the circumferential direction of the tile and 60% of the radial direction of the tile.

In the present example, the pressure distribution of the liquid film before the use of the interface slip effect is shown in fig. 3, and the pressure distribution after the use of the interface slip effect is shown in fig. 4. As can be seen from fig. 4, a large pressure spike is generated by the liquid film at the boundary between the region I and the region II, thereby improving the bearing capacity of the bearing; the fluid viscosity in the area I is greatly reduced, so that the bearing capacity is reduced. The minimum film thickness of the bearing can be improved by 50%, and the friction torque can be reduced by 60%.

Example 2

In the embodiment, the optimized thrust bearing has the outer diameter of 800mm, the inner diameter of 400mm, the wrap angle of 40 degrees, the radial deflection coefficient of 0.524 and the circumferential deflection coefficient of 0.5, the tile is preprocessed with an arc bulge with the diameter of 25 mu m, the normal working rotating speed is 1500rpm, and the average working pressure is 0.544 MPa.

As shown in fig. 1, the upper surface of the pad is divided into two regions: the area I and the rest area II are close to the inlet area, wherein the area I is subjected to surface treatment to form a hydrophobic surface, so that the lower ultimate shear stress is realized, and interface slippage is easy to occur; the area II is subjected to surface treatment to form a hydrophilic surface, so that the shear stress is higher, and interface slippage is not easy to occur.

In the embodiment, the area I accounts for 60% along the circumferential direction of the tile and 60% along the radial direction of the tile.

In the embodiment, the minimum film thickness of the bearing utilizing the interface slip effect can be improved by 45%, and the friction torque can be reduced by 52%.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, which may be variously modified and changed. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

The working principle of the invention is as follows:

in the working process, fluid enters from the inlet of the tile and flows out from the outlet, and when the fluid passes through the area I, the shear stress near the surface of the tile is greater than the surface limit shear stress, so that the solid-liquid surface generates interface slippage, and the fluid speed near the tile is greater than the theoretical non-slippage value. And when the tile passes through the area II, because the ultimate shear stress of the surface of the tile is larger than the shear stress of the fluid, no interface slip occurs between the solid and the liquid surfaces, so that the fluid velocity near the tile tends to 0. When the area I flows to the area II, the fluid speed is suddenly reduced, and in order to ensure the continuity of the fluid flow in the flow, a pressure spike (as shown in fig. 3 and 4) is generated at the boundary, so that the bearing capacity is increased, and the friction torque of the bearing is reduced due to the reduction of the fluid viscosity force in the area I. At the same time, the height of the region I is low, which also ensures that the hydrophobic components in the region I are not abraded during the start-stop phase.

Claims

1. A complex sliding surface tilting pad thrust bearing comprising a plurality of pads, wherein the upper surface of said pads is divided into two regions: the area I and the rest area II are close to the inlet area, wherein the area I is subjected to surface treatment to form a hydrophobic surface, so that the lower ultimate shear stress is realized, and interface slippage is easy to occur; the region II is subjected to surface treatment to form a hydrophilic surface, so that the ultimate shear stress is high, interfacial slippage is not easy to occur, one boundary of the region I is an inlet edge, and the region II surrounds the region I on the boundary except the inlet edge.

2. A tilting pad thrust bearing with complex sliding surface according to claim 1, characterized in that the height of said area I is lower than the height of area II to protect the hydrophobic surface in area I from wear due to start-up and shut-down procedures.

3. A tilting pad thrust bearing with complex sliding surface according to claim 2, characterized in that the height difference between the area I and the area II is determined according to the working condition parameters of the actual operation of the bearing, and is in the same order of magnitude as the minimum film thickness of the liquid film in the operation of the thrust bearing.

4. A complex sliding surface tilting pad thrust bearing according to claim 1 wherein the circumferential extent of said region I is no more than 75% of the total pad wrap angle.

5. A tilting pad thrust bearing with complex sliding surface according to claim 4, characterized in that under the working condition of the eccentric support bearing, the area I accounts for 75% of the circumference and 60% of the radial direction of the pad; under the working condition of the central support bearing, the area I accounts for 60 percent in the circumferential direction and 60 percent in the radial direction of the pad.