A load-carrying performance controllable active gas bearing

Abstract

The present application relates to the technical field of gas bearing, and discloses an active gas bearing with adjustable bearing performance, aiming at the problem that high-speed airflow circumferential shear is easy to induce cross-coupling instability. The bearing comprises a shaft sleeve, a piezoelectric stack actuator, a flexible hinge, a metal rubber damping element and a top foil. The inner hole wall of the shaft sleeve is provided with first and second installation grooves and a fixing groove arranged alternately; the actuator and the independently processed flexible hinge are sequentially built-in the first installation groove, and the damping element is embedded on one side of the two types of installation grooves close to the shaft center; one end of the top foil is fixed in the fixing groove, and circumferentially adheres to one side of the damping element close to the shaft center. By adjusting the voltage, the actuator generates a micro-displacement, which is linearly guided and transmitted through the flexible hinge, and actively pushes the top foil to reconstruct the gas film to break the asymmetric pressure field. The present application realizes the dynamic regulation and control of stiffness, effectively avoids resonance, and significantly improves the dynamic stability of the high-speed rotor system.

Description

Technical Field

[0001] This invention relates to the field of gas bearing technology, specifically to an active gas bearing with adjustable load-bearing capacity, suitable for support systems in high-speed rotating machinery, such as micro gas turbines, air compressors, high-speed motors, and other equipment. Background Technology

[0002] Gas-lubricated bearings are high-performance non-contact support components based on the hydrodynamic lubrication effect of gas. Their traditional configuration typically consists of a bearing sleeve, an elastic support structure, and a top layer of foil. The core working mechanism lies in the formation of a micron-sized wedge-shaped convergent space between the rotor surface and the top layer of foil when the rotor rotates at high speed. This geometry exerts strong shearing and compression hydrodynamic effects on the internal viscous gas, thereby establishing a high-rigidity and high-load-bearing gas film within the micron-sized gap. This lubricating gas film not only supports the rotor in achieving stable non-contact levitation and significantly reduces mechanical friction loss, but also provides necessary structural damping in conjunction with the deformation of the underlying flexible support, enabling it to exhibit excellent service performance under extreme conditions such as high speed, high temperature, and oil-free lubrication.

[0003] In high-speed rotating machinery, the performance of the supporting components directly determines the overall operational efficiency and reliability of the machine. However, the stiffness and damping characteristics of traditional foil bearings are limited by the inherent geometry and material properties of their structure, resulting in a purely passive support mechanism. This makes it difficult to achieve optimal performance matching under complex and variable operating conditions such as wide frequency ranges and varying loads. More seriously, as the rotational speed increases dramatically, the cross-coupling stiffness within the air film increases significantly, easily inducing cross-coupling instability. Especially when the rotor crosses the critical speed, passive supports often cannot provide sufficient damping to suppress large-amplitude vibrations, leading to rotor system instability and seriously threatening the safe operation of the equipment.

[0004] A piezoelectric stacked actuator is a precision actuator that achieves electromechanical energy conversion based on the inverse piezoelectric effect. Its core component is formed by stacking multiple layers of piezoelectric ceramic sheets using a precision press-fit packaging process. Under precise control of the excitation voltage, this actuator can output high-precision mechanical displacement at the micrometer level, and has become an indispensable drive component in high-end electromechanical systems such as precision gap adjustment and active vibration suppression.

[0005] As a typical compliant mechanism, flexible hinges primarily rely on the local elastic deformation of materials to achieve controllable micro-displacement transmission. Due to their elastic design without mechanical joints, flexible hinges completely eliminate the mechanical friction and fit clearance inherent in traditional kinematic pairs, endowing the system with excellent transmission performance characterized by zero backlash and zero mechanical hysteresis.

[0006] While existing active support technologies have incorporated piezoelectric drive, they often face technical bottlenecks such as complex transmission structures, large radial space requirements, or mechanical hysteresis in force transmission. There is an urgent need for a new type of intelligent support solution that is compact, responsive, and capable of large-range stiffness control. Summary of the Invention

[0007] To address the limitations of existing passive support technologies, this invention aims to provide an active gas bearing with adjustable load-bearing capacity. This bearing, through the synergistic action of a piezoelectric actuator and an independent flexible hinge mechanism, achieves precise modification of the bearing's gas film clearance and converging wedge-shaped spatial morphology. Upon receiving an external excitation electrical signal, it can match the optimal dynamic pressure principal stiffness to the system in real time, thereby significantly widening the stability margin of the rotor system and greatly improving the system's instability threshold.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: An active gas bearing with adjustable load-bearing capacity, comprising: a bushing, a piezoelectric stacked actuator, a flexible hinge, a metal-rubber damping element, and a top layer foil. The inner wall of the bushing is machined with three types of groove structures, specifically including: three first mounting grooves evenly distributed at 120° intervals along the circumference; three second mounting grooves evenly distributed at 120° intervals along the circumference and staggered at 60° from the first mounting grooves; and a fixing groove formed in the inner wall of the bushing for inserting and fixing the top layer foil.

[0009] Furthermore, within the first mounting slot, a piezoelectric stacked actuator, a flexible hinge, and a metal-rubber damping element are sequentially assembled radially from the outer side towards the center of the inner hole; wherein the piezoelectric stacked actuator is embedded in the first mounting slot at the end furthest from the axis. The second mounting slot contains only the metal-rubber damping element, used to provide passive damping support for the system.

[0010] Furthermore, the flexible hinge is an independently manufactured elastic transmission component, which is embedded in the first mounting groove; the radial outer end of the flexible hinge abuts against the piezoelectric stacked actuator, and its radial inner end abuts against the metal rubber damping element, which is used to linearly guide and transmit the mechanical displacement output by the piezoelectric stacked actuator.

[0011] Furthermore, the top layer foil is circumferentially attached to and covers the surface of all metal rubber damping elements on the side near the shaft center; one end of the top layer foil serves as a fixed end, inserted into and secured in the fixed groove of the bushing to restrict its circumferential sliding, while the other end extends along the airflow direction and is in an unconstrained free state to adapt to the elastic coordinated deformation when the rotor is running at high speed.

[0012] Furthermore, the piezoelectric stacked actuator, in conjunction with the metal-rubber damping element, pushes the top layer foil, providing initial support stiffness and assembly preload to the system. During dynamic operation, the piezoelectric stacked actuator generates minute radial mechanical deformation driven by an external excitation electrical signal. This mechanical deformation, guided by the independently configured flexible hinge and transmitted through the metal-rubber damping element, actively alters the air film gap and wedge-shaped spatial morphology between the top layer foil and the rotor, thereby achieving dynamic adjustment of the equivalent hydrodynamic bearing stiffness.

[0013] The technical solution adopted in this invention has the following significant advantages: This invention innovatively introduces a collaborative structure of piezoelectric stacked actuators and independently fabricated flexible hinges. The flexible hinge overcomes the clearance errors of traditional mechanical joints, linearly guiding the micron-level precision displacement generated by the piezoelectric element, and transmitting it non-destructively to the top foil through a metal-rubber damping element, achieving extremely high stiffness control precision. This displacement is efficiently transmitted through the non-destructive and compliant guidance of the flexible hinge, and directly acts on the top foil through the metal-rubber damping element, thereby achieving precise reconstruction of the bearing air film gap and the converging wedge space. This mechanism of actively changing the air film morphology based on precision displacement not only significantly enhances the hydrodynamic bearing effect to reduce frictional losses, but also effectively alleviates the circumferential asymmetric disturbance caused by excessive compression of high-speed airflow in the wedge space by changing the air film gap. This fundamentally weakens the cross-coupling effect that easily induces rotor eddy instability, and greatly improves the dynamic stability margin of the rotor system. Addressing the engineering problem of severe resonance easily triggered when a high-speed rotor crosses the critical speed, this invention proposes a dynamic stiffness matching scheme. When the rotor approaches the resonance region, the equivalent dynamic pressure stiffness of the bearing can be changed by instantaneously adjusting the excitation electrical signal applied to the actuator, thus actively forcing the critical speed of the system to shift. After passing the resonance region, the initial voltage state is restored, which can effectively avoid the resonance peak and provide a practical and reliable intelligent support hardware foundation for the safe operation of high-speed rotating machinery. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0015] Figure 2 This is an exploded view of the present invention;

[0016] Figure 3 This is a schematic diagram of the bushing structure of the present invention;

[0017] Figure 4 This is a schematic diagram of the piezoelectric stacked actuator structure of the present invention;

[0018] Figure 5 This is a schematic diagram of the flexible hinge structure of the present invention;

[0019] Figure 6 This is a schematic diagram of the metal-rubber damping element structure of the present invention;

[0020] In the figure: 1. Bushing, 2. Piezoelectric stacked actuator, 3. Flexible hinge, 4. Metal-rubber damping element, 5. Top layer foil. Detailed Implementation

[0021] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. However, it should be understood that the following specific embodiments are merely preferred technical solutions of the present invention and should not be construed as limiting the present invention. Figures 1 to 6 As shown, an active gas bearing with adjustable load-bearing capacity mainly includes a bushing (1), a piezoelectric stacked actuator (2), a flexible hinge (3), a metal-rubber damping element (4), and a top foil (5). The inner wall of the bushing (1) is machined with two sets of circumferentially staggered and equidistantly distributed groove structures. One set consists of three circumferentially evenly distributed first mounting grooves spaced 120° apart. Within these grooves, the piezoelectric stacked actuator (2), the independently machined flexible hinge (3), and the metal-rubber damping element (4) are sequentially assembled radially from the outside to the inside. Specifically, the piezoelectric stacked actuator (2) is embedded in the end of the first mounting groove away from the axis; the flexible hinge (3) is embedded in the middle of the groove, with its radially outer end abutting against the actuator (2) and its radially inner end abutting against the damping element (4); the other set consists of three circumferentially evenly distributed second mounting grooves spaced 120° apart, used only for mounting the metal-rubber damping element (4). In addition, a dedicated fixing groove is machined into the inner wall of the bushing (1).

[0022] In terms of overall assembly, the top foil (5) is attached and covered circumferentially on the surface of all metal rubber damping elements (4) near the axis; one end of the top foil (5) is inserted into and fixed in the fixing groove to restrict its circumferential sliding, while the other end extends along the airflow direction and remains in an unconstrained free state to adapt to the air film expansion and flexible coordinated deformation under operating conditions.

[0023] In a static or initial working state, the piezoelectric stacked actuator (2) works in conjunction with the metal rubber damping element (4) to push the top foil (5) to provide initial support stiffness and assembly preload for the system.

[0024] During dynamic operation and control, the system precisely adjusts the external electrical signal applied to the piezoelectric stacked actuator (2), driving it to generate micron-level mechanical deformation in the radial direction. This minute mechanical deformation is transmitted non-destructively and precisely through independent flexible hinges (3), and then actively changes the air film gap and wedge-shaped space morphology between the top layer foil (5) and the high-speed rotor through the compliant pushing of the metal-rubber damping element (4). The active change in the air film gap effectively enhances the hydrodynamic bearing effect and weakens the cross-coupling effect, realizing online control of the bearing's main stiffness characteristics.

[0025] Based on the above structure, the bearing in this embodiment can perfectly cooperate with the dynamic control strategy to overcome resonance: when the operating speed of the bearing-rotor system approaches its inherent critical speed, a precise displacement is generated by actively outputting a transiently changing excitation electrical signal to the piezoelectric stacked actuator (2); after this displacement is transmitted to the top foil (5), the equivalent dynamic compressive stiffness of the bearing undergoes a transient jump. The change in stiffness characteristics directly reshapes the overall dynamic boundary conditions of the system, actively pushing the actual critical speed of the system outside the current operating frequency band, thereby effectively avoiding the excitation of resonance peaks. After the rotor accelerates smoothly and moves away from the original critical speed range, the excitation signal is adjusted synchronously to smoothly restore the bearing stiffness to the initial set state. This "active offset" to "signal reset" logic implemented based on the hardware structure of this invention can greatly improve the operating stability of the bearing-rotor system across the entire speed range.

[0026] It should be noted that the above embodiments are merely preferred embodiments of the present invention and do not constitute a substantial limitation on the scope of protection of the present invention. The circumferential arrangement combination within the bushing (1) is not limited to... Figure 1 The structure shown can be adapted to other symmetrical or asymmetrical multi-point array arrangements by those skilled in the art in practical engineering applications. Furthermore, the top foil (5) can be configured as a single-piece foil structure continuously covering the inner hole, or as a multi-watt foil structure formed by overlapping and splicing multiple independent foils circumferentially. These equivalent transformations are all within the scope of protection of this invention.

Claims

1. An active gas bearing with adjustable load-bearing capacity, characterized in that, include: The bushing (1), piezoelectric stacked actuator (2), flexible hinge (3), metal rubber damping element (4), and top foil (5) are provided. The inner wall of the bushing (1) is provided with three types of groove structures, including: three first mounting grooves evenly distributed at 120° intervals along the circumference; three second mounting grooves evenly distributed at 120° intervals along the circumference and staggered with the first mounting grooves at 60°; and a fixing groove opened on the inner wall of the bushing (1) for inserting and fixing the top foil (5). The piezoelectric stacked actuator (2), flexible hinge (3), and metal rubber damping element (4) are sequentially assembled in the first mounting groove from the outer side to the center of the inner hole. The piezoelectric stacked actuator (2) is built into the first mounting groove at the end away from the axis. Only the metal rubber damping element (4) is embedded in the second mounting groove to provide passive damping support for the system.

2. The active gas bearing with adjustable load-bearing capacity according to claim 1, characterized in that: The flexible hinge (3) is an independently processed elastic transmission component, which is embedded in the first mounting groove; the radial outer end of the flexible hinge (3) abuts against the piezoelectric stacked actuator (2), and its radial inner end abuts against the metal rubber damping element (4), which is used to linearly guide and transmit the mechanical displacement output by the piezoelectric stacked actuator (2).

3. The active gas bearing with adjustable load-bearing capacity according to claim 1, characterized in that: The top foil (5) is attached and covered circumferentially on the surface of all metal rubber damping elements (4) near the shaft center; one end of the top foil (5) is inserted into and fixed in the fixing groove of the bushing (1) to restrict its circumferential sliding, while the other end extends along the airflow direction and is in an unconstrained free state to adapt to the elastic coordinated deformation when the rotor is running at high speed.

4. The active gas bearing with adjustable load-bearing capacity according to claim 1, characterized in that: In a static or initial working state, the piezoelectric stacked actuator (2) works in conjunction with the metal rubber damping element (4) to push the top foil (5) to provide initial support stiffness and assembly preload for the system.

5. The active gas bearing with adjustable load-bearing capacity according to claim 1, characterized in that: In dynamic operation, the piezoelectric stacked actuator (2) generates a small radial mechanical deformation based on the drive of the external excitation electrical signal. This mechanical deformation is guided by the independently set flexible hinge (3) and transmitted by the metal rubber damping element (4), actively changing the air film gap and wedge-shaped space morphology between the top layer foil (5) and the rotor, thereby realizing the dynamic adjustment of the equivalent dynamic pressure support stiffness of the bearing.

6. The active gas bearing with adjustable load-bearing capacity according to claim 1, characterized in that: The piezoelectric stacked actuator (2), flexible hinge (3) and metal rubber damping element (4) are arranged in a multi-point array with equal angle symmetry or asymmetry along the circumference of the bushing (1); and the top layer foil (5) is configured as a single foil structure that continuously covers the inner hole, or a multi-watt foil structure formed by overlapping and splicing multiple independent foils along the circumference.

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