Multi-stage variable-stiffness variable-damping composite bearing

Abstract

The invention provides a multi-stage variable-stiffness variable-damping composite bearing, which belongs to the technical field of bearing design and comprises a bearing bush 1, a variable-stiffness variable-damping interlayer and a metal shell, the bearing bush and the metal shell are of a cylindrical structure. The variable-rigidity variable-damping interlayer comprises a multi-stage variable-rigidity variable-damping cell element array, and cell elements are arrayed between the bearing bush and the metal shell in the axial direction and the radial direction of the stern bearing. The multi-stage variable-stiffness variable-damping bearing bush cell element is of a tower-shaped structure and comprises a plurality of stages of substructures. When each stage of substructure is designed, based on the actual dynamic load borne by the ship propulsion shafting, a material with proper elastic modulus and damping characteristics is selected; when material selection is limited, effective response to different load working conditions is achieved by adjusting the shape and size of the multi-stage variable-stiffness variable-damping cell element structure. The anti-abrasion capacity of the stern bearing can be enhanced, the service life of the bearing is remarkably prolonged, the influence of vibration on the structural service life and noise can be reduced, and the dynamic stability of a shaft system is remarkably enhanced.

Description

Technical Field

[0001] The invention belongs to the technical field of bearing design and relates to a multi-stage variable stiffness and variable damping composite bearing. Technical Background

[0002] The stern bearing is a radial liquid sliding bearing, sometimes also called the tail bearing. It is located on the propeller side of the ship's propulsion shaft system and provides radial support for the entire propeller and shaft system. It is an extremely critical component in the ship's propulsion system. Whether it is a surface or underwater ship, the inertial force caused by the operation of the propeller, the exciting force of the non-uniform flow field on the propeller, and other various uncertain loads will be mainly transmitted to the stern bearing support through the stern bearing, thereby exciting the vibration and sound radiation of the hull structure. Therefore, the stern bearing has an important impact on the vibration and noise level of the ship. Especially for modern ships, excessive vibration and noise not only affect the accuracy and performance of precision instruments on the ship, but also put the crew at risk of hearing damage. At the same time, the huge weight of the stern shaft and propeller will cause the stern bearing to bear severe eccentric loads and cause the stern shaft to have non-negligible tilt and bending deformation. The journal and the bearing may have local contact at the edge, causing severe friction and wear or vibration noise. With the increase in ship tonnage, the adverse effects of this eccentric load will become more prominent. In addition, for patrol ships and coast guard ships, their working conditions need to change constantly according to the mission. For example, they need to run at low speed during covert patrols, while they need to run at high speed during emergency maneuvers. At low speeds, the bearing fluid dynamic pressure effect is weak, and the stern bearing will be in an extremely unfavorable mixed lubrication state. High speeds mean large shaft loads and vibrations, and the stern bearing also needs to be able to adapt to this variable working condition. Therefore, the stern bearing must have good load adaptability, deformation compliance, and excellent anti-friction and wear performance, so that it can adapt to the above-mentioned various environments and working conditions.

[0003] In order to improve the performance of stern bearings, people are currently focusing on two aspects: bearing materials and structural optimization design. In terms of materials, metal-based materials and wood-based materials were mainly used in the early days, but metal materials have problems such as seawater corrosion and severe wear on the journal, while wood-based materials have resource limitations, and are now less used. Although ceramic-based materials have low friction factors and good wear and corrosion resistance, they are easy to break under impact or vibration loads due to their high brittleness, and due to their high hardness, they have poor tolerance for particles such as mud and sand in the water, so they are not very suitable for stern bearings. In recent years, polymer materials such as rubber, ultra-high molecular weight polyethylene, cerium, polyetheretherketone, and polyimide have been increasingly used in stern bearings, but these materials also have their own advantages and disadvantages and cannot meet the various requirements of stern bearings. For example, rubber, modified rubber and rubber-based composite materials have the advantages of good hydrophilicity, good tolerance to foreign matter, and low friction coefficient in water. In addition, their good elasticity and damping properties give them excellent dynamic vibration absorption performance and insensitivity to journal deflection. However, such materials also have disadvantages such as low load-bearing capacity, difficult to control dimensional deviation, large dry friction coefficient, and easy to produce stick-slip vibration noise under low speed and heavy load. While high molecular weight polyethylene, polyetheretherketone, polyimide and other polymer materials have good wear resistance and self-lubrication, which can better solve the friction and wear problems under low speed and heavy load conditions, but such materials have average tolerance to foreign matter, are more sensitive to shaft diameter inclination, and have average anti-vibration energy absorption performance. It can be seen that there is no so-called perfect material at present, and it must be assisted by structural optimization design. The popular practice is to process micro grooves on the surface of the bearing to increase the fluid dynamic pressure effect of the bearing, but this method is only effective in the early stage. As the use time increases, the effect will be greatly reduced due to the change of groove configuration caused by wear. In addition, some studies have proposed the use of a multi-layer composite bearing design, which can fully utilize the characteristics of each layer of material. However, due to the layered laying, it is a series structure with fixed stiffness and damping, and cannot adapt well to the characteristics of variable loads on the stern bearing.

[0004] In summary, the current design of the stern bearing cannot meet its comprehensive performance requirements, and a new design is urgently needed. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention provides a multi-stage variable stiffness and variable damping composite bearing, which can enable the bearing to better cope with variable working conditions, heavy loads and eccentric loads, effectively reduce local friction and wear of the bearing, simulate shaft system vibration, and reduce or even eliminate the noise problem induced by vibration. In addition, the bearing naturally has the adaptability to complex nonlinear dynamic loads. When used in the stern bearing of a ship, it can greatly enhance the maneuverability of the ship and improve the reliability of key components of the shaft system.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A multi-stage variable stiffness variable damping composite bearing, comprising: a bearing bush 1, a variable stiffness variable damping interlayer 2, and a metal shell 3; the bearing bush 1 is a cylindrical structure; the metal shell 3 is a cylindrical structure, serving as a supporting structure of the composite bearing. The variable stiffness variable damping interlayer 2 is located between the bearing bush 1 and the metal shell 3.

[0008] Furthermore, the bearing bush 1 is a single-layer structure, and its material is a polymer material with excellent friction and wear properties such as ultra-high molecular weight polyethylene, sialon, polyetheretherketone, polyimide, etc.

[0009] Furthermore, the variable stiffness variable damping interlayer 2 comprises a multi-stage variable stiffness variable damping cell array, and the multi-stage variable stiffness variable damping cells are arrayed between the bearing shell 1 and the metal shell 3 along the axial and radial directions of the stern bearing to support the bearing shell 1.

[0010] Furthermore, the multi-stage variable stiffness and variable damping bearing cell is a tower-shaped structure, including multiple substructures (first-stage substructure, second-stage substructure, third-stage substructure...Nth-stage substructure), the top curvature of each substructure is the same as the curvature of the outer wall of the bearing 1, and the bottom curvature of each substructure is the same as the curvature of the inner wall of the metal shell 3. The top of the first-stage substructure is initially in contact with the outer wall of the bearing 1, and the subsequent second-stage substructure to the Nth-stage substructure are all clearance-fitted with the outer wall of the bearing 1, and the clearance increases with the increase of the number of substructures, and the bottom ends of the substructures at each stage are all fixedly connected to the inner wall of the metal shell 3.

[0011] Furthermore, the cross-section of the first-level substructure is a rectangular structure, the cross-sections of the second-level substructure to the N-level substructure are U-shaped, and there is a certain gap between the substructures. The first-level substructure is arranged at the center of the multi-level variable stiffness bearing cell, and the second-level substructure to the N-level substructure are arranged with the first-level substructure as the center and expand outward step by step to form a cell structure.

[0012] Furthermore, when designing the substructures of each level of the multi-stage variable stiffness variable damping bearing cell, materials with suitable elastic modulus and damping characteristics can be preferentially selected based on the actual dynamic load borne by the ship propulsion shaft system. When faced with material selection restrictions, the shape and size of the multi-stage variable stiffness variable damping cell structure can be adjusted to achieve effective response to different load conditions, thereby ensuring the flexibility of stiffness and damping adjustment to the greatest extent and enhancing the universality of dynamic response adjustment.

[0013] The beneficial effects of the present invention are:

[0014] (1) The bearing shell in the multi-stage variable stiffness and variable damping composite bearing of the present invention is in direct contact with the journal. The bearing shell material is made of high molecular weight polyethylene, sialon, polyetheretherketone, polyimide, nylon and other polymer materials with excellent friction and wear properties. Such materials have good self-lubricating properties, can effectively improve the lubrication characteristics of the stern bearing under low speed and heavy load, reduce friction power consumption, greatly enhance the wear resistance of the stern bearing, and thus significantly extend the service life of the bearing.

[0015] (2) The interlayer in the multi-stage variable stiffness and variable damping composite bearing of the present invention is made of materials with good elasticity and damping properties, which can weaken the adverse effects of severe working conditions such as journal tilt, eccentric load and heavy load, and reduce the unevenness of load. At the same time, the good damping properties of the interlayer material play a key role in vibration suppression, reducing the negative impact of vibration on structural life and noise.

[0016] (3) The interlayer in the multi-stage variable stiffness and variable damping composite bearing of the present invention adopts a multi-stage structure. As the load increases, each stage of the substructure will contact the bearing in turn, causing the contact stiffness and damping of the bearing to gradually increase, thereby forming adaptability to the load, being able to quickly and automatically respond to shaft system vibrations, and significantly enhancing the dynamic stability of the shaft system.

[0017] (4) The stiffness and damping of the variable stiffness variable damping bearing interlayer can be adjusted by selecting different materials. The order, size, shape, etc. of the substructure in the variable stiffness variable damping cell can also be adjusted. The substructures at each level can be made of the same material or different materials, which provides design flexibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A schematic diagram of a multi-stage variable stiffness and variable damping composite bearing according to an embodiment;

[0019] Figure 2 A vertical cross-sectional schematic diagram of a multi-stage variable stiffness and variable damping composite bearing according to an embodiment;

[0020] Figure 3 A schematic cross-sectional view of a multi-stage variable stiffness and variable damping composite bearing according to an embodiment;

[0021] Figure 4 A schematic diagram of a single cell structure with variable stiffness and variable damping in a multi-stage variable stiffness and variable damping composite bearing according to an embodiment;

[0022] Figure 5 A schematic cross-sectional view of a single cell structure with variable stiffness and variable damping in a multi-stage variable stiffness and variable damping composite bearing according to an embodiment;

[0023] Figure 6 It is a schematic longitudinal section diagram of a single cell AA with variable stiffness and variable damping in a multi-stage variable stiffness and variable damping composite bearing according to an embodiment;

[0024] In the figure, 1 is a bearing; 2 is a variable stiffness variable damping interlayer; 3 is a metal shell; 4 is a variable stiffness variable damping single cell structure; 5 is a cell primary substructure; 6 is a cell secondary substructure; 7 is a cell tertiary substructure. DETAILED DESCRIPTION

[0025] The embodiments of the technical solution of the present invention will be described in detail below with reference to the accompanying drawings.

[0026] like Figure 1-6 As shown, this embodiment provides a three-stage variable stiffness and variable damping composite bearing design, including a bearing 1, a variable stiffness and variable damping interlayer 2, and a metal shell 3, wherein the variable stiffness and variable damping interlayer 2 is composed of sixty-four groups of variable stiffness and variable damping cells 4, and each cell 4 includes a primary substructure 5, a secondary substructure 6, and a tertiary substructure 7.

[0027] The metal shell 3 is a supporting structure of the bearing, used to support the bearing 1 and the variable stiffness interlayer 2 inside. In this embodiment, there are a total of sixty-four groups of three-level variable stiffness variable damping cells 4 arranged between the bearing 1 and the metal shell 3 along the axial and circumferential directions of the bearing, of which four groups of variable stiffness variable damping cells 4 are arranged along the axial direction and sixteen groups are arranged along the circumferential direction. The bottom of each level of the three-level variable stiffness variable damping cell 4 is fixedly connected to the inner wall of the metal shell 3, the top of the first level substructure 5 of the three-level variable stiffness variable damping cell 4 is fixedly connected to the outer wall of the bearing 1, and the top of the second level substructure 6 of the cell 4 and the third level substructure 7 of the cell 4 are initially in clearance fit with the outer wall of the bearing 1, wherein the clearance between the third level substructure 7 and the bearing 1 is slightly larger than the clearance between the second level substructure 6 and the bearing 1, thereby ensuring that the substructures of each level in the cell 4 are in contact with the bearing 1 successively when the load changes.

[0028] The bearing bush 1 is made of polyetheretherketone, which has good wear resistance and extremely low friction coefficient, and can better adapt to low-speed heavy-load conditions. The primary, secondary and tertiary substructures in the variable stiffness variable damping cell 4 are all made of nitrile rubber with good elasticity and damping properties, so that the bearing has good dynamic load adaptability and vibration suppression ability.

[0029] When the composite bearing is subjected to a small load (related to the designed load range, to be confirmed according to specific circumstances), the bearing 1 will only contact the primary substructure 5 of the variable stiffness variable damping cell 4. At this time, the overall stiffness of the bearing is small, and it can provide timely feedback to small changes in external loads. The good damping properties of the primary substructure 5 in the single variable stiffness variable damping cell 4 can effectively suppress vibration. As the load increases, the bearing 1 will simultaneously contact the primary substructure 5 and the secondary substructure 6 of the multi-stage variable stiffness variable damping cell 4, and the overall contact stiffness of the bearing will increase; as the load further increases, the primary substructure 5, the secondary substructure 6, and the tertiary substructure 7 of the multi-stage variable stiffness variable damping cell 4 in the bearing bearing area will successively contact the bearing 1, ensuring the gradual graded changes in the overall stiffness and damping of the bearing bearing, and improving the load adaptability of the bearing.

[0030] During load changes, the fluid between the primary substructure 5, the secondary substructure 6, and the tertiary substructure 7 in the multi-stage variable stiffness and variable damping cell 4 will be squeezed out or sucked into the gap, and the viscosity of the fluid will produce additional damping effect, further improving the dynamic stability of the bearing.

[0031] In summary, the multi-stage variable stiffness and variable damping composite bearing described in the present invention combines the advantages of materials and structures, and provides a new bearing design for complex load environments and variable operating conditions, which can effectively reduce shaft system vibration, noise, friction and wear, and can effectively improve bearing life, reliability and operational stability.

[0032] The above-described embodiment only expresses one embodiment of the present invention, and its description is more specific, but it is not intended to limit the scope of the present invention. It should be pointed out that after reading the present invention, those skilled in the art can implement various adjustments and optimizations without departing from the principles of the present invention, and these improvements should be deemed to fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be subject to the claims.

Claims

1. A multi-stage variable stiffness and variable damping composite bearing, characterized in that: The multi-stage variable stiffness and variable damping composite bearing comprises a bearing bush (1), a variable stiffness and variable damping interlayer (2), and a metal shell (3); the bearing bush (1) is a cylindrical structure; the metal shell (3) is a cylindrical structure, serving as a supporting structural member of the composite bearing; the variable stiffness and variable damping interlayer (2) is located between the bearing bush (1) and the metal shell (3).

2. A multi-stage variable stiffness and variable damping composite bearing according to claim 1, characterized in that: The bearing bush (1) is a single-layer structure, and its material is a polymer material such as ultra-high molecular weight polyethylene, sialon, polyetheretherketone, and polyimide.

3. The multi-stage variable stiffness and variable damping composite bearing according to claim 1, characterized in that: The variable stiffness variable damping interlayer (2) comprises a multi-stage variable stiffness variable damping cell array, wherein the multi-stage variable stiffness variable damping cells are arrayed between the bearing shell (1) and the metal shell (3) along the axial and radial directions of the stern bearing, and play a supporting role for the bearing shell (1).

4. A multi-stage variable stiffness and variable damping composite bearing according to claim 3, characterized in that: The multi-stage variable stiffness variable damping bearing cell is a tower-shaped structure, comprising a multi-stage substructure: a first-stage substructure, a second-stage substructure, a third-stage substructure ... an Nth-stage substructure; the top curvature of each stage substructure is the same as the curvature of the outer wall surface of the bearing (1), and the bottom curvature of each stage substructure is the same as the curvature of the inner wall surface of the metal shell (3); the top of the first-stage substructure is initially in contact with the outer wall surface of the bearing (1), and the subsequent second-stage substructure to the Nth-stage substructure are all clearance-fitted with the outer wall surface of the bearing (1), and the clearance increases as the number of substructure stages increases; the bottom ends of the substructures at each stage are all fixedly connected to the inner wall surface of the metal shell (3).

5. The multi-stage variable stiffness and variable damping composite bearing according to claim 4, characterized in that: The cross-section of the first-level substructure is a rectangular structure, and the cross-sections of the second-level substructure to the N-level substructure are U-shaped. There is a certain gap between the substructures. The first-level substructure is arranged at the center of the multi-level variable stiffness bearing cell, and the second-level substructure to the N-level substructure are arranged with the first-level substructure as the center and expand outward step by step to form a cell structure.

6. The multi-stage variable stiffness and variable damping composite bearing according to claim 4, characterized in that: When designing each level of substructure of the multi-stage variable stiffness and variable damping bearing cell, materials with suitable elastic modulus and damping characteristics are selected based on the actual dynamic load borne by the ship's propulsion shaft system; when material selection is limited, the shape and size of the multi-stage variable stiffness and variable damping cell structure are adjusted to achieve response to different load conditions.

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