Combined hydraulic thrust device for bearing loading and control method

Abstract

This invention belongs to the field of bearing testing technology, specifically disclosing a combined hydraulic thrust device and control method for bearing loading. It includes a mechanical loading module, a hydraulic pump station, and a controller. The mechanical loading module comprises a loading rod, a housing, a force sensor, a transition sleeve, a thrust sleeve, a linear bearing, a hydraulic cylinder assembly, and a rigid support. The housing is connected to the rigid support, the rigid support is connected to the hydraulic cylinder assembly, the hydraulic cylinder assembly is in contact with the thrust sleeve, the right end of the thrust sleeve is connected to the force sensor, and the right end of the force sensor is connected to the loading rod. This device has a compact structure and high overall rigidity. Through various combinations of a central hydraulic cylinder, side hydraulic cylinder groups, and a full cylinder group, the device decomposes the target load into multiple subsystems, ensuring precise force transmission. It is particularly suitable for performance and fatigue testing of components such as high-speed bearings and wind turbine bearings, which have extreme requirements for load range, accuracy, and dynamic performance.

Description

Technical Field

[0001] This invention relates to the field of bearing testing technology, and specifically to a combined hydraulic thrust device and control method for bearing loading. Background Technology

[0002] In reliability testing of high-speed precision bearings (such as aero-engine main shaft bearings) and large wind turbine main shaft bearings, the loading system needs to accurately reproduce extreme and complex operating conditions ranging from no-load, light-load, full-load to overload. During the test, the bearing load ranges from hundreds of Newtons in simulated light-load start-up conditions to thousands of Newtons in extreme conditions, resulting in a wide load test range and a large force value span.

[0003] In existing technologies, the solution for achieving this type of dynamic loading is an electro-hydraulic servo loading system. Its structure consists of a high-precision proportional servo valve controlling a single-piston-rod hydraulic cylinder, with a closed-loop feedback system formed by a force sensor installed between the cylinder and the load, achieving precise control of the output force. However, this structure presents an inherent and irreconcilable technical contradiction: the load force range, control accuracy, and system dynamic response performance cannot be simultaneously optimized in a single actuator. Specifically, to cover the maximum load requirements, a large-diameter proportional servo valve and a large-area hydraulic cylinder must be selected. However, when applying extremely small loads, the system requires very low operating pressure, forcing the proportional servo valve to operate in the "high-gain, strong nonlinear" region near zero on its flow-pressure characteristic curve. At this point, the system's control stability is poor, and it is highly susceptible to oil contamination and frictional changes, leading to low control accuracy under small loads, and even load oscillations. Conversely, if a small-diameter valve and a small-area cylinder are selected to pursue high accuracy and stability under small loads, the system will experience sluggish response due to insufficient flow supply when outputting large loads, failing to meet dynamic testing requirements. Although the selected high-performance proportional servo valve has a high pressure regulation ratio (e.g., up to 0.3~21MPa), for ultra-wide force range requirements, a single valve and cylinder combination cannot maintain excellent performance across the entire range.

[0004] Therefore, there is an urgent need for a solution that is highly integrated, intelligently controlled, and capable of continuous, stable, and high-precision loading of loads ranging from extremely small to huge within a compact unit. Summary of the Invention

[0005] To address the problems existing in the background art, the present invention provides a combined hydraulic thrust device and control method for bearing loading.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a combined hydraulic thrust device for bearing loading, comprising a mechanical loading module, a hydraulic pump station, and a controller. The mechanical loading module includes a loading rod, a housing, a force sensor, a transition sleeve, a thrust sleeve, a linear bearing, a hydraulic cylinder assembly, and a rigid support. The left end of the housing is connected to the rigid support, and the left end of the rigid support is connected to the hydraulic cylinder assembly. A guide hole is provided on the left end face of the rigid support. The hydraulic cylinder assembly is in contact with the left end face of the thrust sleeve. The thrust sleeve is disposed in the guide hole of the rigid support. The right end of the thrust sleeve is connected to the force sensor, and the right end of the force sensor is connected to the loading rod. The loading rod applies a load to the outside. The hydraulic pump station drives the central hydraulic cylinder through the first servo valve to form a first control loop; the hydraulic pump station drives the first side hydraulic cylinder and the second side hydraulic cylinder through the second servo valve to form a second control loop. The controller detects and feeds back the actual load on the force sensor in real time. Based on the difference between the actual load and the target load command F_cmd received by the controller, and using a multi-mode combination control strategy, it sends control commands to the first servo valve and the second servo valve respectively, driving the corresponding hydraulic cylinders to perform four combined actions: micro-precision mode, medium-high precision mode, full-cylinder coordination mode, and extreme full-power mode. In the micro-precision mode, only the central hydraulic cylinder outputs power; in the medium-high precision mode, only the first and second side hydraulic cylinders output power; in the full-cylinder coordination mode, the first side hydraulic cylinder, the central hydraulic cylinder, and the second side hydraulic cylinder simultaneously output power at a set power; and in the extreme full-power mode, the first side hydraulic cylinder, the central hydraulic cylinder, and the second side hydraulic cylinder simultaneously output power at maximum power.

[0007] A linear bearing is installed in the guide hole on the left end face of the rigid support. The inner hole of the linear bearing is adapted to the outer diameter of the thrust sleeve to form a precision sliding pair, which constrains the thrust sleeve to translate along the axis.

[0008] The hydraulic cylinder assembly includes a first side hydraulic cylinder, a central hydraulic cylinder, a second side hydraulic cylinder, and a base plate; the base plate is located at the right end of the hydraulic cylinder assembly and is bolted to the left end face of the rigid support; the central hydraulic cylinder is laterally arranged in the middle of the hydraulic cylinder assembly, and the first side hydraulic cylinder and the second side hydraulic cylinder are respectively located above and below the central hydraulic cylinder.

[0009] The first side hydraulic cylinder is equipped with a first side hydraulic cylinder piston rod, the central hydraulic cylinder is equipped with a central hydraulic cylinder piston rod, and the second side hydraulic cylinder is equipped with a second side hydraulic cylinder piston rod; the right ends of the first side hydraulic cylinder piston rod, the central hydraulic cylinder piston rod, and the second side hydraulic cylinder piston rod pass through the base plate and contact the left end face of the thrust sleeve.

[0010] The contact surfaces of the piston rods of the first side hydraulic cylinder, the central hydraulic cylinder, and the second side hydraulic cylinder with the thrust sleeve are provided with elastic material.

[0011] A transition sleeve is provided between the thrust sleeve and the force sensor. The left end face of the transition sleeve is connected to the right end face of the thrust sleeve by bolts, and the right end face of the transition sleeve is connected to the left end face of the force sensor by bolts.

[0012] A control method for a combined hydraulic thrust device for bearing loading, wherein the threshold values ​​for mode switching are set to F1, F2, and F3 according to the magnitude of the target load F_cmd, and different combinations of hydraulic cylinders are selected to drive the device in the following four modes: Micro-precision mode: When |F_cmd| ≤ F1, the first control loop is activated; the controller outputs a command to the first servo valve to drive the central hydraulic cylinder. Medium-high precision mode: When F1 < |F_cmd| ≤ F2, the first control loop is closed and the second control loop is activated; the controller closes the first servo valve and outputs a command to the second servo valve to drive the first side hydraulic cylinder and the second side hydraulic cylinder to work. Full cylinder coordination mode: When F2 < |F_cmd| ≤ F3, the first control loop and the second control loop are activated; the controller simultaneously outputs commands to the first servo valve and the second servo valve to drive the first side hydraulic cylinder, the center hydraulic cylinder and the second side hydraulic cylinder to work. Extreme Full Power Mode: When |F_cmd| > F3, the first control circuit and the second control circuit are activated; the controller simultaneously outputs commands to the first servo valve and the second servo valve to drive the first side hydraulic cylinder, the center hydraulic cylinder and the second side hydraulic cylinder to reach or approach the maximum working pressure.

[0013] The threshold values ​​F1, F2, and F3 are set based on the maximum working force of the hydraulic cylinder; the maximum force of the central hydraulic cylinder and the side hydraulic cylinders is: Maximum working force of the central hydraulic cylinder: F_cmax = P_max * A_c; Maximum working force of the hydraulic cylinders on both sides: F_smax = P_max * 2 * A_s; Maximum force when three cylinders work together: F_totalmax = P_max * (A_c + 2*A_s); In the formula: P_max is the maximum working pressure, A_c is the effective piston area of ​​the central hydraulic cylinder, and A_s is the effective piston area of ​​the side hydraulic cylinder; The values ​​are F1 = F_cmax * 80%, F2 = F_smax * 70%, and F3 = F1 + F_smax * 90%.

[0014] The beneficial effects of this invention are as follows: This invention provides a combined hydraulic thrust device and control method for bearing loading. The device has a compact structure and high overall rigidity. Through various combinations of central hydraulic cylinder, side hydraulic cylinder group, and full cylinder group, the target load is decomposed into multiple subsystems, and the force transmission is accurate. It fundamentally solves the contradiction of a single valve and cylinder system, and is particularly suitable for performance and fatigue testing of components such as high-speed bearings and wind power bearings that have extreme requirements for load range, accuracy and dynamic performance. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the overall system configuration of the present invention.

[0016] Figure 2 This is a structural schematic diagram of the mechanical loading module.

[0017] In the diagram: 1. Loading rod, 2. Housing, 3. Force sensor, 4. Transition sleeve, 5. Thrust sleeve, 6. Linear bearing, 7. First side hydraulic cylinder, 8. Central hydraulic cylinder, 9. Second side hydraulic cylinder, 10. Rigid support, 11. First side hydraulic cylinder piston rod, 12. Central hydraulic cylinder piston rod, 13. Second side hydraulic cylinder piston rod, 14. Hydraulic pump station, 15. First servo valve, 16. Second servo valve, 17. Controller. Detailed Implementation

[0018] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. 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.

[0019] The following detailed description of specific embodiments of the present invention, in conjunction with the accompanying drawings, illustrates the following: A combined hydraulic thrust device for bearing loading includes a mechanical loading module, a hydraulic pump station 14, and a controller 17. The mechanical loading module includes a loading rod 1, a housing 2, a force sensor 3, a transition sleeve 4, a thrust sleeve 5, a linear bearing 6, a hydraulic cylinder assembly, and a rigid support 10. The left end of the housing 2 is connected to the rigid support 10, and the left end of the rigid support 10 is connected to the hydraulic cylinder assembly. A guide hole is provided on the left end face of the rigid support 10. The hydraulic cylinder assembly is in contact with the left end face of the thrust sleeve 5. The hydraulic cylinder assembly includes a first side hydraulic cylinder 7, a central hydraulic cylinder 8, and a second side hydraulic cylinder. 9 and base plate; the base plate is located at the right end of the hydraulic cylinder assembly and is bolted to the left end face of the rigid support 10; the central hydraulic cylinder 8 is laterally arranged in the middle of the hydraulic cylinder assembly, and the first side hydraulic cylinder 7 and the second side hydraulic cylinder 9 are respectively located above and below the central hydraulic cylinder 8; the first side hydraulic cylinder 7 is provided with a first side hydraulic cylinder piston rod 11, the central hydraulic cylinder 8 is provided with a central hydraulic cylinder piston rod 12, and the second side hydraulic cylinder 9 is provided with a second side hydraulic cylinder piston rod 13; the right ends of the first side hydraulic cylinder piston rod 11, the central hydraulic cylinder piston rod 12, and the second side hydraulic cylinder piston rod 13 pass through the base plate and meet the left end face of the thrust sleeve 5. The first side hydraulic cylinder piston rod 11, the central hydraulic cylinder piston rod 12, and the second side hydraulic cylinder piston rod 13 are in contact with the thrust sleeve 5, and the contact surfaces of these parts are provided with elastic material. The thrust sleeve 5 is located in the guide hole of the rigid support 10. A linear bearing 6 is provided in the guide hole on the left end face of the rigid support 10. The inner hole of the linear bearing 6 is adapted to the outer diameter of the thrust sleeve 5 to form a precision sliding pair, which constrains the thrust sleeve 5 to translate along the axis. At the same time, the linear bearing 6 can greatly reduce the friction force during the operation of the thrust sleeve 5. The right end of the thrust sleeve 5 is connected to the force sensor 3. A transition sleeve 4 is provided between the thrust sleeve 5 and the force sensor 3. The left end face of the transition sleeve 4 is connected to the right end face of the thrust sleeve 5 by bolts. The right end face of sleeve 4 is connected to the left end face of force sensor 3 by bolts; the function of transition sleeve 4 is to adjust the distance between thrust sleeve 5 and force sensor 3 so that the invention can adapt to various experimental environments; the right end of force sensor 3 is connected to loading rod 1, which applies a load to the outside; during the experiment, the piston rod 11 of the first side hydraulic cylinder, the piston rod 12 of the central hydraulic cylinder, or the piston rod 13 of the second side hydraulic cylinder moves to the right, applying a thrust to thrust sleeve 5, causing thrust sleeve 5 to move to the right. The magnitude of this thrust is measured by force sensor 3 and fed back to controller 17 in real time; the movement of thrust sleeve 5 to the right drives loading rod 1 to move to the right, thereby applying a load to the outside. The hydraulic pump station 14 drives the central hydraulic cylinder 8 through the first servo valve 15 to form a first control loop; the hydraulic pump station 14 drives the first side hydraulic cylinder 7 and the second side hydraulic cylinder 9 through the second servo valve 16 to form a second control loop. The controller 17 detects and provides feedback on the actual load on the force sensor 3 in real time. Based on the difference between the actual load and the target load command F_cmd received by the controller 17, and using a multi-mode combination control strategy, it sends control commands to the first servo valve 15 and the second servo valve 16 respectively, driving the corresponding hydraulic cylinders to perform four combined actions: micro-precision mode, medium-high precision mode, full-cylinder coordination mode, and extreme full-power mode. In the micro-precision mode, only the central hydraulic cylinder 8 outputs power; in the medium-high precision mode, only the first side hydraulic cylinder 7 and the second side hydraulic cylinder 9 output power; in the full-cylinder coordination mode, the first side hydraulic cylinder 7, the central hydraulic cylinder 8, and the second side hydraulic cylinder 9 simultaneously output power at a set power; and in the extreme full-power mode, the first side hydraulic cylinder 7, the central hydraulic cylinder 8, and the second side hydraulic cylinder 9 simultaneously output power at maximum power. The control method for a combined hydraulic thrust device for bearing loading sets mode switching thresholds F1, F2, and F3 based on the target load F_cmd. F1, F2, and F3 are set according to the maximum working force of the hydraulic cylinder. In this embodiment, the system's maximum working pressure P_max = 21 MPa, and the effective piston area A_c of the central hydraulic cylinder 8 = 5*10 -4 m², the effective piston area of ​​each side hydraulic cylinder A_s = 5*10 -3 m², the maximum force of the central hydraulic cylinder 8 and the side hydraulic cylinders is: Maximum working force of the central hydraulic cylinder: F_cmax = P_max * A_c = 10.5 kN; Maximum working force of the hydraulic cylinders on both sides: F_smax = P_max * 2 * A_s = 210 kN; The maximum force of the three cylinders working together is: F_totalmax = P_max * (A_c + 2*A_s) = 220.5 kN; In the formula: P_max is the maximum working pressure, A_c is the effective piston area of ​​the central hydraulic cylinder 8, and A_s is the effective piston area of ​​the side hydraulic cylinder; Based on the calculation results of the central hydraulic cylinder 8 and the side hydraulic cylinders, the thresholds F1, F2, and F3 for mode switching are calculated as follows: F1 = F_cmax * 80% = 8.4kN ≈ 8kN F2 = F_smax * 70% = 147k ≈ 150kN F3=F_cmax*80%+F_smax*90%=197.4kN≈200kN; The selection of different hydraulic cylinder combinations is divided into the following four modes: Micro-precision mode: When |F_cmd| ≤ F1, the first control loop is activated; the controller 17 outputs a command to the first servo valve 15 to drive the central hydraulic cylinder 8 to work; at this time, the output force is 8kN, and the maximum pressure inside the central hydraulic cylinder 8 is about 16MPa. The hydraulic cylinder is in the working area with good linearity and high resolution. Medium-high precision mode: When F1 < |F_cmd| ≤ F2, the first control loop is closed and the second control loop is activated; the controller 17 closes the first servo valve 15 and outputs a command to the second servo valve 16 to drive the first side hydraulic cylinder 7 and the second side hydraulic cylinder 9 to work; since the oil circuits are connected in parallel and the parameters of the two cylinders are consistent, they theoretically output equal forces and jointly bear the total load; Full-cylinder coordinated mode: When F2 < |F_cmd| ≤ F3, the first control loop and the second control loop are activated; the controller 17 simultaneously outputs commands to the first servo valve 15 and the second servo valve 16 to drive the first side hydraulic cylinder 7, the central hydraulic cylinder 8, and the second side hydraulic cylinder 9 to work; in actual operation, a simple force distribution scheme is generally adopted. For example, the central hydraulic cylinder 8 bears a fixed base force (e.g., 80% of the maximum force of the central hydraulic cylinder 8, approximately 8.4kN), and the remaining load is shared equally by driving the first side hydraulic cylinder 7 and the second side hydraulic cylinder 9; the controller 17 controls the two loops simultaneously to achieve force synthesis; Extreme Full Power Mode: When |F_cmd| > F3, the system enters full power mode, activating the first control loop and the second control loop; the controller 17 simultaneously outputs commands to the first servo valve 15 and the second servo valve 16, driving the first side hydraulic cylinder 7, the center hydraulic cylinder 8 and the second side hydraulic cylinder 9 to reach or approach the maximum working pressure; that is, the first side hydraulic cylinder 7, the center hydraulic cylinder 8 and the second side hydraulic cylinder 9 can output the system's ultimate force of 220.5kN.

[0020] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0021] The parts of this invention not described in detail are prior art.

Claims

1. A combined hydraulic thrust device for bearing loading, comprising a mechanical loading module, a hydraulic pump station (14), and a controller (17), characterized in that: The mechanical loading module includes a loading rod (1), a housing (2), a force sensor (3), a transition sleeve (4), a thrust sleeve (5), a linear bearing (6), a hydraulic cylinder assembly, and a rigid support (10); the left end of the housing (2) is connected to the rigid support (10), the left end of the rigid support (10) is connected to the hydraulic cylinder assembly, and the left end face of the rigid support (10) is provided with a guide hole; the hydraulic cylinder assembly is in contact with the left end face of the thrust sleeve (5); the thrust sleeve (5) is located in the guide hole of the rigid support (10), the right end of the thrust sleeve (5) is connected to the force sensor (3), the right end of the force sensor (3) is connected to the loading rod (1), and the loading rod (1) applies a load to the outside; The hydraulic pump station (14) drives the central hydraulic cylinder (8) through the first servo valve (15) to form a first control loop; the hydraulic pump station (14) drives the first side hydraulic cylinder (7) and the second side hydraulic cylinder (9) through the second servo valve (16) to form a second control loop; The controller (17) detects and feeds back the actual load on the force sensor (3) in real time. Based on the difference between the actual load and the target load command F_cmd received by the controller (17), the controller sends control commands to the first servo valve (15) and the second servo valve (16) respectively, according to the multi-mode combination control strategy, and drives the corresponding hydraulic cylinder to perform four combined actions: micro-precision mode, medium-high precision mode, full cylinder coordination mode and extreme full power mode. The micro-precision mode is powered only by the central hydraulic cylinder (8), the medium-high precision mode is powered only by the first side hydraulic cylinder (7) and the second side hydraulic cylinder (9), the full cylinder coordination mode is powered by the first side hydraulic cylinder (7), the central hydraulic cylinder (8) and the second side hydraulic cylinder (9) at the same set power, and the extreme full power mode is powered by the first side hydraulic cylinder (7), the central hydraulic cylinder (8) and the second side hydraulic cylinder (9) at the same maximum power.

2. The combined hydraulic thrust device for bearing loading according to claim 1, characterized in that: A linear bearing (6) is provided in the guide hole on the left end face of the rigid support (10). The inner hole of the linear bearing (6) is matched with the outer diameter of the thrust sleeve (5) to form a precision sliding pair, which constrains the thrust sleeve (5) to translate along the axis.

3. The combined hydraulic thrust device for bearing loading according to claim 1, characterized in that: The hydraulic cylinder assembly includes a first side hydraulic cylinder (7), a central hydraulic cylinder (8), a second side hydraulic cylinder (9), and a base plate; the base plate is located at the right end of the hydraulic cylinder assembly and is bolted to the left end face of the rigid support (10); the central hydraulic cylinder (8) is laterally arranged in the middle of the hydraulic cylinder assembly, and the first side hydraulic cylinder (7) and the second side hydraulic cylinder (9) are respectively located above and below the central hydraulic cylinder (8).

4. The combined hydraulic thrust device for bearing loading according to claim 3, characterized in that: The first side hydraulic cylinder (7) is provided with a first side hydraulic cylinder piston rod (11), the central hydraulic cylinder (8) is provided with a central hydraulic cylinder piston rod (12), and the second side hydraulic cylinder (9) is provided with a second side hydraulic cylinder piston rod (13). The right ends of the first side hydraulic cylinder piston rod (11), the central hydraulic cylinder piston rod (12), and the second side hydraulic cylinder piston rod (13) pass through the bottom plate and contact the left end face of the thrust sleeve (5).

5. The combined hydraulic thrust device for bearing loading according to claim 4, characterized in that: The contact surfaces of the first side hydraulic cylinder piston rod (11), the center hydraulic cylinder piston rod (12), and the second side hydraulic cylinder piston rod (13) with the thrust sleeve (5) are provided with elastic material.

6. The combined hydraulic thrust device for bearing loading according to claim 1, characterized in that: A transition sleeve (4) is provided between the thrust sleeve (5) and the force sensor (3). The left end face of the transition sleeve (4) is connected to the right end face of the thrust sleeve (5) by bolts, and the right end face of the transition sleeve (4) is connected to the left end face of the force sensor (3) by bolts.

7. A control method for a combined hydraulic thrust device for bearing loading, characterized in that: The aforementioned control method for a combined hydraulic thrust device for bearing loading sets mode switching thresholds of F1, F2, and F3 based on the target load F_cmd, and selects different combinations of hydraulic cylinders to drive in the following four modes: Micro-precision mode: When |F_cmd| ≤ F1, the first control loop is activated; the controller (17) outputs a command to the first servo valve (15) to drive the central hydraulic cylinder (8) to work; Medium-high precision mode: When F1 < |F_cmd| ≤ F2, the first control loop is closed and the second control loop is opened; the controller (17) closes the first servo valve (15) and the controller (17) outputs a command to the second servo valve (16) to drive the first side hydraulic cylinder (7) and the second side hydraulic cylinder (9) to work. Full cylinder coordination mode: When F2 < |F_cmd| ≤ F3, the first control loop and the second control loop are opened; the controller (17) simultaneously outputs commands to the first servo valve (15) and the second servo valve (16) to drive the first side hydraulic cylinder (7), the center hydraulic cylinder (8) and the second side hydraulic cylinder (9) to work. Extreme full power mode: When |F_cmd| > F3, the first control loop and the second control loop are opened; the controller (17) simultaneously outputs commands to the first servo valve (15) and the second servo valve (16) to drive the first side hydraulic cylinder (7), the center hydraulic cylinder (8) and the second side hydraulic cylinder (9) to reach or approach the maximum working pressure.

8. The control method for a combined hydraulic thrust device for bearing loading according to claim 7, characterized in that: The threshold values ​​F1, F2, and F3 are set according to the maximum working force of the hydraulic cylinder; the maximum force of the central hydraulic cylinder (8) and the side hydraulic cylinders is: Maximum working force of the central hydraulic cylinder: F_cmax = P_max * A_c; Maximum working force of the hydraulic cylinders on both sides: F_smax = P_max * 2 * A_s; Maximum force when three cylinders work together: F_totalmax = P_max * (A_c + 2*A_s); Where: P_max is the maximum working pressure, A_c is the effective piston area of ​​the central hydraulic cylinder (8), and A_s is the effective piston area of ​​the side hydraulic cylinder; The values ​​are F1 = F_cmax * 80%, F2 = F_smax * 70%, and F3 = F1 + F_smax * 90%.

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