Ship bearing radial loading test bench and method for simulating ice load and water immersion working conditions

Abstract

The invention belongs to the technical field of ship bearings, and particularly relates to a ship bearing radial loading test bench and method for simulating ice load and water immersion working conditions, and the method comprises the steps: installing a to-be-tested intermediate bearing on a test platform, enabling the intermediate bearing to sleeve a test shaft, starting a cooling water circulation system to control the flow, cooling water enters a cooling water coil pipe to establish oil pool cooling circulation; a driving motor is started; a test shaft stably operates through equipment such as a reduction gearbox and the like; a dynamic pressure lubrication state is established, a radial dynamic load or a stable constant load is applied through a hydraulic loading system to simulate an icebreaking load working condition, and a simulated water body is injected into a water tank; the test conditions of the intermediate bearing in a ship immersion environment are constructed through water pressure adjustment, the temperatures of lubricating oil, a bearing bush and cooling water are monitored in real time, the loading force is adjusted through feedback data, and the performance of the intermediate bearing is judged after the test is finished. The problems that ice excitation and soaking environment simulation are insufficient and a loading structure is eccentric in the prior art are solved, and high-precision cooling and thermal stability evaluation are achieved.

Description

Technical Field

[0001] The present application belongs to the technical field of ship bearings, and specifically relates to a ship bearing radial loading test bench and method for simulating ice load and water immersion conditions. Background Art

[0002] In modern marine propulsion systems, intermediate bearings are crucial components for supporting the radial loads of the ship's shafting system. Their performance is directly linked to the safety and reliability of the vessel's navigation. To ensure the stability and reliability of intermediate bearings in practical applications, they undergo systematic performance verification on specially designed test benches. This verification process helps identify potential design or manufacturing flaws before a product is put into service, thereby optimizing structural design, improving product quality, and reducing the risk of safety incidents caused by bearing failure.

[0003] Especially in special types of ships such as icebreakers, the service environment of intermediate bearings is even more stringent. During icebreaking operations, the bearings must withstand frequent low speeds, heavy loads, and periodic ice excitation loads. Operating under alternating load conditions for a long time can easily cause structural fatigue and wear, and in severe cases, may cause system failure. In addition, icebreakers are at risk of damage in extreme sea conditions. Once the intermediate bearing is completely submerged in seawater, its shell must still maintain good sealing and maintain the continuous and stable operation of the power system. This places higher demands on the sealing performance and operating capabilities of the intermediate bearing in extreme environments such as high humidity, high pressure, and alternating hot and cold temperature differences.

[0004] Existing methods for verifying intermediate bearing performance primarily focus on static or dynamic evaluation of their radial load capacity. Traditional approaches typically employ test platforms designed to simulate actual shipboard operating conditions, rotating a test shaft and applying radial force to simulate bearing operation. Patent No. CN104215457A, for example, proposes an intermediate bearing testing device and method. This device employs a hydraulic loading device positioned directly below the intermediate bearing, applying radial force from bottom to top to simulate the external loads experienced by the bearing during ship propulsion.

[0005] Although the above scheme has achieved the simulation of radial loading of the intermediate bearing to a certain extent, it still has the following shortcomings, which restrict the applicability of the system and the authenticity and validity of the test results:

[0006] 1. Lack of simulation capabilities for ice excitation and submersion environments: Existing test equipment does not simulate and verify the periodic ice excitation conditions and cabin submersion conditions faced by icebreakers during navigation in ice areas, and cannot effectively evaluate the structural strength, fatigue performance and sealing performance of the intermediate bearing in such extreme environments.

[0007] 2. The loading structure occupies space and has eccentricity risks: Since the loading structure is arranged at the bottom of the bearing, it will significantly raise the center of gravity of the test platform during medium and large-sized bearing tests. This not only takes up a large amount of installation space, but also easily leads to eccentric torque during the loading process, thereby causing the risk of overturning or resonance of the test bench, reducing test safety and control stability.

[0008] 3. Loading force direction poses challenges to the connection structure: This solution utilizes a bottom-up loading path, requiring the loading force to be transmitted back to the bearing system through the test platform and connecting bolts. This loading path subjects the connection structure to a long-term reverse load state. Under high loads or dynamic loading conditions, this can easily lead to fatigue failure of the connection surface or deformation of the platform structure, requiring additional structural reinforcement and mechanical simulation verification, increasing design and manufacturing costs.

[0009] 4. Unable to truly simulate complex service environments, and the loading conditions lack authenticity: Existing test systems generally lack the ability to simulate extreme environmental factors such as "seawater immersion", "high water pressure", and "hot and cold temperature differences", resulting in significant differences between the test environment and the actual service environment, affecting the representativeness and engineering applicability of the test results. In particular, in terms of temperature and pressure factors, their impact on lubricating oil film formation, sealing structure stability, loading force distribution, etc. has not been fully considered. For example, under high temperature conditions, the thickness of the lubricating oil film decreases and the friction coefficient increases, which increases the bearing resistance perceived by the loading system and affects the determination of mechanical parameters; under high water pressure conditions, the sealing structure may produce compression deformation, which in turn leads to water infiltration and changes in force distribution, affecting the accuracy of radial loading data.

[0010] 5. Limited applicable bearing cooling type and lack of temperature control mechanism: The above solution is primarily applicable to air-cooled intermediate bearings and does not address the design of a cooling system for water-cooled intermediate bearings. This single cooling method limits the test device's adaptability to different bearing types. Furthermore, the temperature control and monitoring are only rudimentary, lacking a systematic temperature control circuit and multi-point temperature monitoring mechanism, making it incapable of supporting high-load tests that significantly impact thermal properties.

[0011] 6. The loading method is indirect, and the loading accuracy and uniformity are limited: The method of loading upward through a single hydraulic cylinder and indirectly transmitting force through the platform has a long loading path, limited force distribution uniformity, and a limited adjustment range. It is difficult to precisely control the loading status of different parts, which restricts high-precision testing.

[0012] In summary, the existing technology still has obvious deficiencies in verifying the adaptability of intermediate bearings to extreme environments. There is an urgent need for an intermediate bearing test system that can simulate complex load conditions such as seawater immersion, high water pressure, thermal shock, and ice excitation, so as to more realistically restore the service environment of icebreakers and comprehensively improve the performance verification capabilities and engineering applicability of bearings. Summary of the Invention

[0013] To address the problems of the aforementioned prior art, such as unreasonable loading structures, lack of temperature control mechanisms, and insufficient environmental simulation capabilities, this application proposes a radial loading test rig and method for ship bearings that simulate ice load and flooding conditions. A specialized test rig with controllable water pressure and temperature is designed and constructed. This test system is specifically designed for multi-condition performance verification of intermediate bearings on icebreakers. With controllable water pressure and temperature, it can cover typical extreme conditions such as steady-state open-water propulsion, periodic ice excitation impact, and hull flooding. This test platform integrates a hydraulic loading system, a water tank heating and pressure control device, and a cooling water circulation loop, specifically designed to evaluate the performance of intermediate bearings under large shaft diameters, high loads, and complex temperature and pressure environments. By precisely controlling water temperature, pressure, and loading force, and monitoring the bearing's operating status in real time, dynamic loading and thermomechanical coupling testing are achieved under extreme conditions such as simulated hull damage and flooding. This test rig effectively improves the authenticity and engineering adaptability of intermediate bearing performance verification, enhances the accuracy and representativeness of test data, and provides strong support for structural optimization and seal reliability assessment.

[0014] On the one hand, the present application provides a ship bearing radial loading test method for simulating ice load and immersion conditions. The ship bearing radial loading test method is implemented using a ship bearing radial loading test bench. The ship bearing radial loading test bench includes a work platform, a multi-point temperature monitoring system, a test shaft, an intermediate bearing, and a drive system, a hydraulic loading system, a cooling water circulation system, a water tank, and a test system installed on the work platform. The water tank has through-holes on both sides, and the intermediate bearing is installed inside the water tank. The water tank contains a water tank heating element with a set temperature and pressurized water for simulating seawater immersion conditions.

[0015] The intermediate bearing includes a bearing housing, a bearing shell, and a cooling water coil. The bearing housing is provided with a cavity, and a mounting hole is provided axially through the cavity and the housing wall. The bearing shell is installed in the mounting hole and forms a sliding fit with the test shaft. The cooling water coil is arranged in the oil pool area at the bottom of the bearing housing. Its water inlet and water outlet are respectively connected to the cooling water circulation system for circulating and cooling the lubricating oil.

[0016] The test shaft is installed through the bearing shell, and its two ends pass horizontally through the shaft holes on both sides of the water tank. The output shaft of the drive system is connected to one end of the test shaft to drive its rotation; the hydraulic loading system is symmetrically arranged on both sides of the intermediate bearing, and a loading end is provided on the top of the hydraulic loading system. The two ends of the test shaft are respectively connected to the corresponding loading ends to apply symmetrical radial loads to the test shaft; the multi-point temperature monitoring system includes a plurality of temperature sensors, whose probes are respectively arranged inside the bearing shell and in the oil pool area, for real-time monitoring of the bearing shell temperature and the lubricating oil temperature;

[0017] The hydraulic loading system includes a first hydraulic cylinder, a second hydraulic cylinder, a hydraulic cylinder support, a spherical roller bearing, a hydraulic oil pipeline, a valve block, a servo valve and a hydraulic pump station; the first hydraulic cylinder and the second hydraulic cylinder are symmetrically mounted on the working platform through the hydraulic cylinder support, and the top loading ends thereof are respectively provided with spherical roller bearings that cooperate with the connecting sleeves at both ends of the test shaft to apply symmetrical radial loads to the test shaft; the hydraulic oil pipeline includes an oil inlet pipe and an oil return pipe, the first hydraulic cylinder and the second hydraulic cylinder are respectively provided with a hydraulic oil input end and an output end, the output end of the hydraulic pump station is connected to the input end of the first hydraulic cylinder and the second hydraulic cylinder respectively via the oil inlet pipe, and the output end of the first hydraulic cylinder and the second hydraulic cylinder is connected to the return oil port of the hydraulic pump station via the return oil pipe to form a closed hydraulic circulation loop;

[0018] The oil inlet pipe is provided with a servo control branch in parallel at a pipeline position close to the input end of the first hydraulic cylinder and the second hydraulic cylinder, respectively. A valve block is provided on the servo control branch, and a servo valve is fixedly mounted on the valve block. The servo valve is used to receive an electrical signal output by the controller and adjust the flow rate and pressure of the hydraulic oil in the servo control branch to provide variable load hydraulic oil with set amplitude and frequency characteristics to the first hydraulic cylinder and the second hydraulic cylinder;

[0019] The test system includes a controller, a force sensor and an oil pressure sensor connected to the controller via signal lines. The force sensor is installed at the loading end of the hydraulic cylinder, and the oil pressure sensor is set on the hydraulic oil circuit of the valve block.

[0020] The test method includes:

[0021] Step 1: Install the intermediate bearing to be tested on the test platform so that it is sleeved on the test shaft. The bearing shell of the intermediate bearing and the test shaft form a sliding fit, and the water tank is sealed to the test shaft through the skeleton sealing structure.

[0022] Step 2: Start the cooling water circulation system, set the target temperature of the chiller, turn on the chiller and run the cooling water pump. Control the cooling water flow by adjusting the outlet valve of the cooling water tank so that the cooling water enters the cooling water coil installed in the intermediate bearing at a predetermined flow rate, thus establishing the oil pool cooling cycle.

[0023] Step 3: Start the drive motor and make the test shaft run stably at the preset speed through the reduction gearbox, torque meter and coupling. The test shaft is placed in the intermediate bearing bushing and forms a dynamic pressure lubrication state. Turn on the temperature monitoring system and activate the first temperature sensor set inside the bushing, the second temperature sensor arranged in the bearing oil pool, and the temperature sensors set at the water inlet and outlet of the cooling water coil. Establish a multi-point monitoring mechanism for the bearing bushing temperature, lubricating oil temperature and cooling medium temperature.

[0024] Step 4: After the test shaft reaches the target speed, start the hydraulic loading system, close the servo valve, and output constant hydraulic oil to the first and second hydraulic cylinders through the hydraulic pump station to simulate steady-state stress conditions, or open the servo valve, and the controller outputs a control signal of set frequency and amplitude to the servo valve, driving the servo valve to adjust the oil flow and pressure in real time. The variable load hydraulic oil output by the servo control branch merges with the main oil circuit and flows into the hydraulic cylinder, causing the hydraulic cylinder to apply a symmetrical radial dynamic load of predetermined amplitude and frequency to the loading ends of both ends of the test shaft to simulate ice excitation load conditions.

[0025] Step 5: Inject simulated water at a certain temperature and pressure into the water tank. Regulate the water pressure in the water tank using an external water pressure control system to establish the test conditions for the intermediate bearing in a ship's submerged service environment. Set the required water temperature using the water tank heating element, and then perform closed-loop regulation using the temperature control module to create a constant-temperature submersion environment.

[0026] Step 6: Temperature sensors installed inside the bearing, in the oil pool, and at the inlet and outlet of the cooling water coil collect real-time data on the lubricating oil temperature, bearing temperature, and cooling water temperature of the intermediate bearing during operation. The data is collected by the test system and then visualized and stored.

[0027] Step 7: During the loading process, the force sensor and oil pressure sensor monitor the loading force and hydraulic pressure in real time. The test system controller implements closed-loop adjustment of the servo valve control signal based on the feedback data to ensure that the loading curve meets the preset value. After the test, the lubricating oil temperature, bearing shell temperature change trend and lubricating oil water content are used to determine whether the intermediate bearing meets the performance indicators and sealing requirements.

[0028] Step 8: If the intermediate bearing experiences abnormal temperature rise, abnormal oil temperature, or abnormal force loading during the test, the system will automatically issue an alarm command and shut down the hydraulic pump station and drive motor in sequence to terminate the test.

[0029] On the other hand, the present application also provides a test bench for implementing the above-mentioned ship bearing radial loading test method simulating ice load and immersion conditions. The water tank of the test bench includes a water tank lower body and a water tank upper body. The water tank lower body is fixedly installed on the working platform, and the water tank upper body is installed on the water tank lower body. The two together constitute a closed cavity structure.

[0030] In a preferred implementation, the water tank further includes a skeleton seal and a sealing gland; the skeleton seal is installed at the axial hole of the water tank, and the sealing gland presses the skeleton seal.

[0031] In a preferred implementation, further, the test shaft includes an intermediate shaft, connecting bolts and a stepped shaft, and the intermediate shaft is connected to the stepped shafts at both ends respectively through the connecting bolts.

[0032] In a preferred implementation, further, a thrust device is included, which is installed on the second working platform and the top of the thrust device is connected to the stepped shaft at the other end of the test shaft.

[0033] In a preferred implementation, the drive system further includes a drive motor, a reduction gearbox and a torque meter; the output shaft of the drive motor is connected to the input shaft of the reduction gearbox, the output shaft of the reduction gearbox is connected to the input shaft of the torque meter, and the output shaft of the torque meter is connected to the stepped shaft at one end of the test shaft.

[0034] In a preferred implementation, further, the cooling water circulation system includes a cooling water tank, a chiller, a connecting pipe and a flow meter arranged on the connecting pipe, and the water inlet and outlet of the cooling water coil are respectively connected to the cooling water tank and the chiller through the connecting pipe.

[0035] In a preferred implementation, further, the working platform includes a first working platform and a second working platform, the first working platform is used to install the drive system, and the second working platform is used to install the intermediate bearing, the hydraulic loading system and the cooling water circulation system.

[0036] In a preferred implementation, further, the bearing housing includes a bearing cover and a bearing seat, the bearing seat is fixedly mounted on the working platform, the bearing cover is connected to the bearing seat, and the two together define an installation cavity for accommodating the bearing shell.

[0037] In a preferred embodiment, further, an oil pool for storing lubricating oil is provided at the bottom of the bearing seat, and the cooling water coil is provided inside the oil pool to cool the lubricating oil in the oil pool.

[0038] The beneficial effects of this application are:

[0039] First, the radial loading test method for ship bearings of the present application that simulates ice load and immersion conditions can truly restore the working state of ship bearings in complex environments by accurately simulating seawater immersion and ice-excited load conditions. The multi-point temperature monitoring system monitors the temperature of the bearings, lubricating oil and cooling water in real time to ensure that the bearings operate within the optimal temperature range. The hydraulic loading system can apply symmetrical radial dynamic loads or stable constant loads to simulate bearing forces under different working conditions. The cooling water coil and the circulation system work together to effectively cool the lubricating oil and avoid overheating problems. The test system also includes data acquisition and feedback control, which can adjust the loading process in real time and detect abnormal conditions to ensure the accuracy and safety of the test. Through this method, the performance and sealing requirements of the bearings in ice load and seawater immersion environments can be fully verified, the authenticity and reliability of the test can be improved, and data support can be provided for the design optimization of ship bearings.

[0040] Second, the present invention's radial loading test rig for ship bearings, designed to simulate ice loads and submersion conditions, employs a hydraulic loading system symmetrically arranged at both ends of the test shaft. The hydraulic loading system comprises a first hydraulic cylinder and a second hydraulic cylinder, which are connected to a hydraulic pump station via hydraulic oil lines. The hydraulic oil flow and pressure are controlled by adjusting a servo valve to achieve radial dynamic loading on the test shaft. This symmetrical arrangement of the hydraulic system allows for the application of periodic and adjustable ice-excitation loads, simulating the repeated impacts and shocks experienced by icebreakers in ice. This, unlike the constant loads used in traditional loading methods, more realistically reproduces the complex impact forces experienced by bearings during icy navigation. This not only simulates ice-excitation load tests but also allows for the control of hydraulic oil pressure to a preset stable load, enabling steady-state testing. Furthermore, compared to traditional bottom-loading methods, this system avoids problems such as an elevated center of gravity, asymmetric loading paths, and test rig overturning or vibration caused by eccentric moments, thereby improving loading accuracy and system safety. Furthermore, the bearing housing incorporates a built-in oil reservoir and integrated cooling water coil, which, in conjunction with the cooling water circulation system, provides continuous and effective temperature control of the lubricating oil. Compared with air, coolant has a higher specific heat capacity and heat conduction capacity, and can quickly carry away a large amount of heat generated by friction during the operation of the shaft system; through a multi-point temperature monitoring system arranged inside the bearing and the oil pool area, real-time data collection can be performed on the key heat source locations, and a complete temperature control closed-loop feedback loop can be constructed to effectively support high-load thermal stability evaluation; through-shaft holes and skeleton sealing components are set on both sides of the water tank to form a closed space when the bearing is working. By injecting liquid medium of set temperature and pressure into the water tank, seawater immersion and hydrostatic pressure environment are simulated, and the sealing performance, temperature control response and structural stability of the bearing are reproduced under real working conditions, thereby improving the representativeness and accuracy of the test. The test bench has a compact structure, strong adaptability and high controllability. It can fully simulate the stress and thermal environment of the intermediate bearing in actual ship operation, thereby improving the engineering application value and versatility of the test platform.

[0041] Third, in the preferred implementation, the drive system of the present application forms an efficient and stable power transmission chain by sequentially connecting a drive motor, a reduction gearbox and a torque meter, wherein the drive motor provides a controllable power source, the reduction gearbox realizes a reasonable matching of speed and torque, and the torque meter is used to monitor the torque changes and operating status during the test in real time, thereby ensuring that the test shaft runs stably at a preset speed under loading conditions.

[0042] Fourth, in the preferred implementation, the test shaft of the present application adopts a split structure in which the intermediate shaft is connected to the stepped shafts at both ends by connecting bolts, which is convenient for assembly and replacement and ensures the transmission stiffness and axial alignment accuracy; the output shaft of the torque meter is directly connected to the stepped shaft at one end, which can realize real-time torque measurement and precise synchronization of power transmission during loading; the thrust device arranged at the other end is connected to the stepped shaft, which can effectively limit the axial movement of the test shaft during loading and operation.

[0043] Fifth, in the preferred implementation, the cooling water circulation system of the present application forms a closed-loop cooling circuit through a cooling water tank, a chiller, connecting pipes and a flow meter arranged on the pipes. The water inlet and outlet of the cooling water coil are respectively connected to the cooling water tank and the chiller, thereby realizing continuous and efficient cooling and control of the lubricating oil in the oil pool.

[0044] Sixth, in the preferred implementation, the present application adopts a structural design in which the first working platform and the second working platform are arranged in partitions, and the drive system and the intermediate bearing test module are installed separately, which effectively reduces the interference of transmission system vibration and heat on the test accuracy, and facilitates the modular layout and maintenance operations of the equipment; among them, the first working platform is dedicated to the stable installation of the drive system to ensure the stability of power output, and the second working platform is centrally arranged with intermediate bearings, hydraulic loading systems and cooling water circulation systems, which helps to optimize the loading path, simplify the cooling pipe layout and improve the overall structural rigidity.

[0045] Seventh, in the preferred implementation, the present application designs the bearing housing to include a bearing cover and a bearing seat fixedly mounted on the work platform, which together define a bearing installation cavity. An oil pool is provided at the bottom of the bearing seat, and a cooling water coil is integrated inside the oil pool. The lubricating oil can be continuously and effectively cooled during the operation of the intermediate bearing to prevent the oil film from becoming instable or the bearing ablation caused by excessive oil temperature, thereby improving the thermal stability and safety of the test system. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 A schematic diagram of the overall structure of a radial loading test bench for ship bearings simulating ice load and immersion conditions provided by an embodiment of the present invention;

[0047] Figure 2A schematic diagram of a radial loading test bench for ship bearings simulating ice load and immersion conditions provided by an embodiment of the present invention without a water tank installed;

[0048] Figure 3 A schematic diagram of the water tank structure provided by an embodiment of the present invention;

[0049] Figure 4 A schematic diagram of a hydraulic loading system provided in an embodiment of the present invention;

[0050] Figure 5 A schematic diagram of the bow end of an intermediate bearing provided in an embodiment of the present invention;

[0051] Figure 6 A schematic diagram of a cooling water circulation system provided in an embodiment of the present invention;

[0052] Figure 7 A schematic diagram of a cross-sectional structure of a test shaft provided in an embodiment of the present invention;

[0053] Figure 8 A schematic diagram of a test system provided in an embodiment of the present invention;

[0054] Figure 9 This is a flow chart of a method for testing radial loading of ship bearings in a simulated water immersion environment provided by an embodiment of the present invention.

[0055] Among them, 1-first working platform; 2-drive motor; 2.1-drive motor support; 3-reduction gearbox; 3.1-reduction gearbox support; 4-first elastic pin coupling; 5-torque meter; 5.1-torque meter support; 6-second elastic pin coupling; 7-test shaft; 7.1-intermediate shaft; 7.2-connecting bolts; 7.3-stepped shaft; 8-intermediate bearing; 8.1-bearing cover; 8.2-bearing seat; 8.3-bearing shell; 8.4-cooling coil; 8.5-first temperature sensor; 8.6-second temperature sensor; 8.7-housing connecting bolts; 8.8-sealing plate; 9-thrust device; 10-second working platform; 11-hydraulic loading system; 11.1-first hydraulic cylinder; 11.2-second hydraulic cylinder; 11.3-hydraulic cylinder support; 11.4-spherical roller bearing; 11.5-hydraulic oil pipeline; 11.6-valve block; 11.7-servo Service valve; 11.8 - Hydraulic pump station; 12 - Cooling water circulation system; 12.1 - Cooling water tank; 12.2 - Chiller; 12.3 - Connecting pipe; 12.4 - Cooling water pipe output end; 12.5 - Cooling water coil first input end; 12.6 - Cooling water coil second input end; 12.7 - Cooling water coil first output end; 12.8 - Cooling water coil second output end; 12.9 - Chiller input end; 12.10 -Chiller output; 12.11-Cooling water tank input; 12.12-Flowmeter; 13.1-First connecting bolt; 13.2-Water tank lower body; 13.3-Skeleton seal; 13.4-Second connecting bolt; 13.5-Water tank upper body; 13.6-Sealing cover; 13.7-Water inlet; 13.8-Drain outlet; 14-Test system; 14.1-Host; 14.2-Display; 14.3-Controller. DETAILED DESCRIPTION

[0056] In order to enable those skilled in the art to better understand the technical solution of the present application, the present application will be further described in detail below with reference to the accompanying drawings and embodiments.

[0057] The terms "up", "down", "left", "right", "front", and "back" in this application are based on the positional relationships shown in the accompanying drawings. The corresponding positional relationships may vary depending on the drawings, and should not be construed as limiting the scope of protection.

[0058] In this application, the terms "installed," "connected," "connected," "connected," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, integral connection, mechanical connection, electrical connection, or mutual communication. They can also be directly connected or indirectly connected through an intermediate medium. They can also refer to internal communication between two components or interaction between two components. For those skilled in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0059] In icebreaking vessel propulsion systems, intermediate bearings bear the critical tasks of supporting the propulsion shafting, enduring radial loads, withstanding periodic ice excitation, and maintaining stable shafting operation. Because they operate continuously for long periods of time, under heavy loads, and under complex operating conditions, the test bench design must closely mirror actual operating conditions to ensure the authenticity and controllability of loading and operating parameters. During testing, the intermediate bearings primarily bear radial forces. Applying either a stable radial load or a dynamically varying load in a symmetrical and controllable manner is crucial to test bench design. This application aims to provide a test bench and method for radial loading of marine bearings that simulate ice loads and submersion conditions. By employing symmetrical hydraulic loading structures at both ends of the test shaft, uniform and adjustable radial forces can be applied to both sides of the bearing. This not only accurately reproduces the intermediate bearing's force path but also effectively avoids data deviations and structural instability caused by eccentric loading, thereby improving the overall safety and loading accuracy of the test bench. Furthermore, the symmetrical loading structure offers a lower center of gravity and a more compact structure, helping to reduce the test bench height and enhance operational stability, making it suitable for a wide range of testing needs for intermediate bearings of different sizes and types. Furthermore, temperature fluctuations significantly affect the operating state of the intermediate bearing. In order to ensure the accuracy and safety of the test process, it is necessary to build a complete cooling control system and a multi-point temperature monitoring mechanism. By setting up a cooling water circulation system, the lubrication environment temperature of the intermediate bearing can be continuously and stably adjusted to prevent oil film degradation and abnormal heating of the bearing. At the same time, by arranging temperature sensors at the bearing, lubricating oil pool, cooling water inlet and outlet, and environmental positions, a full-process temperature control closed loop is formed to ensure that the system operation is always within a safe range under various simulated load and speed conditions. This structure has good adjustability and engineering application scalability. In summary, this application achieves a high degree of restoration and full-process control of the operating state of the intermediate bearing through the systematic design of the loading structure and the cooling system, improves the test accuracy, adaptability and structural stability, meets the actual needs of high-reliability testing of ship intermediate bearings, and can more accurately and stably simulate the different working loads that the intermediate bearing is subjected to during actual service, and effectively evaluate its structural and thermal stability.

[0060] Example

[0061] Refer to the instruction manual Figure 1-2A radial loading test bench for ship bearings that simulates ice loads and submersion conditions includes a work platform, a multi-point temperature monitoring system, a drive system mounted on the work platform, a test shaft 7, an intermediate bearing 8, a hydraulic loading system 11, a cooling water circulation system 12, a water tank 13, and a testing system 14. Water tank 13 has through-holes on both sides for the test shaft 7 to pass through. Intermediate bearing 8 is mounted within water tank 13, which can be filled with water at a set temperature and pressure to simulate the operating environment of intermediate bearing 8 under ship submersion conditions.

[0062] The intermediate bearing 8 includes a bearing housing, a bearing shell 8.3 and a cooling water coil 8.4. A cavity is provided inside the bearing housing, and an axial mounting hole communicating with the cavity is provided on the housing wall. The bearing shell 8.3 is tightly embedded in the mounting hole to support the test shaft 7. The cooling water coil 8.4 is provided in the oil pool area at the bottom of the bearing housing to achieve forced cooling of the lubricating oil. The oil pool is used to store lubricating oil and provide lubricating medium support between the test shaft 7 and the bearing shell 8.3. The test shaft 7 is installed through the bearing shell 8.3, and its lower half, that is, the area that cooperates with the bearing shell 8.3, is immersed in the lubricating oil in the oil pool when stationary or running at low speed, to ensure that it has the ability to form an initial oil film during the startup phase, thereby effectively reducing friction and wear. Both ends of the test shaft 7 pass horizontally through the axial holes on both sides of the water tank 13. An elastic sealing structure is provided between the test shaft 7 and the axial holes of the water tank 13 to achieve axial sealing during operation to prevent the simulated liquid in the water tank 13 from leaking from the axial holes, thereby ensuring the stability and airtightness of the test environment.

[0063] The water inlet and outlet of the cooling water coil 8.4 are arranged on the side wall of the bearing housing and are connected to the cooling water circulation system 12 through a connecting pipe, so as to achieve continuous cooling of the lubricating oil in the oil pool and maintain the thermal stability of the lubrication environment. The hydraulic loading system 11 is symmetrically arranged on both sides of the intermediate bearing 8. A loading end is provided on the top of the hydraulic loading system 11. The two ends of the test shaft 7 are respectively connected to the loading end through a connecting sleeve, so as to achieve symmetrical radial force on the intermediate bearing 8 during the loading process. The sensor probes of the multi-point temperature monitoring system are respectively arranged inside the bearing 8.3 and in the oil pool area, and are used to detect the working temperature of the bearing and the temperature of the lubricating oil in real time, so as to ensure the accuracy and safety of thermal parameter monitoring during the test process. The output shaft of the drive system is connected to the connecting shaft at one end of the test shaft 7 through a connecting mechanism, which is used to drive the test shaft 7 to run at a preset speed and cooperate with the hydraulic loading system 11 to complete the radial loading test of the intermediate bearing 8.

[0064] As the instruction manual Figure 3The water tank 13 includes a first connecting bolt 13.1, a lower body 13.2, a skeleton seal 13.3, a second connecting bolt 13.4, an upper body 13.5, and a sealing gland 13.6. The lower body 13.2 is fixedly mounted on the work platform via the first connecting bolt 13.1, and the upper body 13.5 is fastened to the lower body 13.2 via the second connecting bolt 13.4, forming a closed cavity structure for containing simulated liquid and generating a certain water pressure environment. Axial holes are provided on both sides of the overall structure formed by the upper body 13.5 and the lower body 13.2, and skeleton seals 13.3 are respectively installed at the axial holes on both sides. The outer side of the skeleton seal 13.3 is compressed by the sealing gland 13.6 to achieve sealing of the rotating part of the test shaft 7. The upper body 13.5 of the water tank is equipped with a water inlet 13.7, and the lower body 13.2 is provided with a drain port 13.8. Drain port 13.8 is used to quickly drain water after the test. During the simulated immersion test, a certain amount of water is injected through the water inlet 13.7, and a controllable water pressure is applied to the water tank interior as required through an external piping system, thereby simulating the submerged environment of the intermediate bearing under actual ship operating conditions.

[0065] It should be noted that the skeleton seal 13.3 is a conventional design and a double-lip rotary shaft seal suitable for rotating shaft sealing applications. It comprises an elastic seal body made of nitrile rubber (NBR) or fluororubber (FKM), a steel band ring stamped from carbon steel or stainless steel, and a wave spring. The elastic seal body has two lip structures: a primary lip and an auxiliary lip. The primary lip contacts the journal surface of the test shaft 7 and performs the primary sealing function, while the auxiliary lip prevents foreign matter from entering and enhances seal life. The steel band ring is embedded within the elastic seal body, providing excellent shape retention and compression support to prevent deformation of the elastic seal body. The wave spring is embedded within the inner circle of the primary lip and continuously applies pressure to the shaft surface, achieving adaptive compression of the sealing lip. If the test shaft deflects or is slightly eccentric due to radial loading, the sealing lip automatically rebounds to maintain the seal. The outer diameter of the elastic seal body is secured to the inner wall of the water tank opening with an interference fit or a gland screw to prevent the sealing ring from loosening or rotating during operation. The skeleton seal 13.3 uses a composite structure of elastic material + spring preload + metal skeleton support to automatically "compensate" for slight deformation or deflection of the shaft surface. When the deflection changes (such as slight bending or beating of the shaft), the lip automatically fits the shaft surface under the action of the spring to achieve dynamic sealing.

[0066] Under real marine environmental conditions, bearings face complex service conditions, including the combined effects of multiple factors such as long-term immersion in water, alternating high and low temperatures, and high water pressure. These environmental variables have a significant impact on the material properties, lubrication status, and seal integrity of the bearings. For example, a high water pressure environment may cause compression deformation or fatigue damage to the sealing structure, thereby increasing the risk of water seepage; in addition, water pressure may also cause micro-deformations in the shaft system and its supporting structure, further forming a complex stress field distribution under the action of radial loads. In high-temperature environments, the thickness of the lubricant film decreases, the friction coefficient increases, and the loading resistance increases; while in low-temperature conditions, the lubricant viscosity increases significantly, and the torque increases during system startup, affecting the overall operating efficiency and reliability.

[0067] To simulate real-world operating conditions and enhance the temperature control capabilities of the test system, in a preferred embodiment of the present application, the water tank 13 further includes a heating element disposed therein, and an insulating layer is provided on the outer surface of the water tank. The heating element can be a resistive heating rod or heating coil, positioned within the bottom or sidewall of the water tank. A stainless steel sheath is preferred for enhanced corrosion resistance. The heating element is secured to the inner wall or base of the water tank via a dedicated mounting bracket. The bracket is made of a high-temperature-resistant, corrosion-resistant alloy and is securely connected to the tank body via mechanical fasteners or welding.

[0068] To prevent leakage or short circuit of the heating elements when working in water, all electric heating elements adopt a fully enclosed waterproof design, and the casing meets the IP68 protection standard. At the same time, the power lead is passed through a multi-sealed sleeve and is led out of the box through a special sealing joint to ensure the sealing and electrical safety of the water tank. The insulation layer covering the outside of the water tank 13 adopts closed-cell insulation material (such as polyurethane foam or aerogel composite board), which can effectively reduce heat loss and improve temperature control efficiency. The thickness of the insulation layer is optimized according to the heat exchange intensity of the external environment to meet the long-term constant temperature requirements under different environmental conditions.

[0069] The heating element is electrically connected to an external temperature control module for automated temperature control. This module, which includes a high-precision temperature sensor (PT100 or thermocouple) and a PID thermostat, collects real-time internal tank temperature data and provides closed-loop control of the heating element. The system also includes a data interface with the test control platform, enabling automated linkage between test condition simulation and environmental regulation, ensuring highly consistent and repeatable performance testing of bearings in various temperature extremes.

[0070] The heating element can be linked to the raw water pressure control system to perform the following parameter combination tests: constant water temperature + variable water pressure (to test the effect of water depth); constant water pressure + variable water temperature (to test the effect of ambient temperature); and multi-temperature zone comparative tests (such as simulating hot and cold cycles). By testing the bearing loading response under different water pressures and temperatures, it is possible to determine the safe operating boundaries of the bearing (water depth + temperature conditions), optimize the selection of sealing structures (materials and structural shapes), provide a scientific basis for the service of ship shafting in different sea areas, and evaluate the adaptability and failure mechanisms of new materials or designs in multi-variable environments.

[0071] As the instruction manual Figure 4 Hydraulic loading system 11 is used to apply a symmetrical and controllable radial load to test shaft 7 to simulate the load state of intermediate bearing 8 in a ship propulsion system. Hydraulic loading system 11 includes a first hydraulic cylinder 11.1, a second hydraulic cylinder 11.2, a hydraulic cylinder support 11.3, and a spherical roller bearing 11.4.

[0072] The first hydraulic cylinder 11.1 and the second hydraulic cylinder 11.2 are respectively mounted on the working platform via hydraulic cylinder supports 11.3. The top loading ends of the first hydraulic cylinder 11.1 and the second hydraulic cylinder 11.2 are provided with spherical roller bearings 11.4, and the connecting shafts at both ends of the test shaft 7 are respectively sleeved in the spherical roller bearings 11.4 of the first hydraulic cylinder 11.1 and the second hydraulic cylinder 11.2. The first hydraulic cylinder 11.1 and the second hydraulic cylinder 11.2 are arranged symmetrically with respect to the test shaft 7, and are respectively mounted on both sides of the working platform and fixed to the platform via hydraulic cylinder supports 11.3 to ensure the stability of the loading direction and loading position. A spherical roller bearing 11.4 is provided at the top of each hydraulic cylinder to cooperate with the connecting sleeves at both ends of the test shaft 7, so that slight angular deviations of the test shaft can be automatically compensated during loading, avoiding eccentric loading and improving loading uniformity.

[0073] The left and right ends of test shaft 7 are inserted into spherical roller bearings 11.4 located at the tops of first and second hydraulic cylinders 11.1 and 11.2, respectively, forming contact points in the radial loading path. During loading, the hydraulic cylinder pistons push spherical roller bearings 11.4 downward, transmitting radial force through test shaft 7 to intermediate bearing 8, achieving the loading effect.

[0074] The hydraulic loading system 11 also includes a hydraulic oil pipeline 11.5, a valve block 11.6, a servo valve 11.7, and a hydraulic pump station 11.8. Hydraulic pump station 11.8, located next to the test platform, serves as the system's pressure source and is equipped with a hydraulic output port and a return port. Hydraulic oil pipeline 11.5 consists of an inlet pipe and a return pipe, respectively used to supply high-pressure hydraulic oil to the first and second hydraulic cylinders 11.1 and 11.2 and to recover used hydraulic oil. The first and second hydraulic cylinders 11.1 and 11.2 each have a hydraulic oil input and output port. The output of hydraulic pump station 11.8 is connected to the input ports of the first and second hydraulic cylinders 11.1 and 11.2, respectively, via the inlet pipe of hydraulic oil pipeline 11.5. The return port of hydraulic pump station 11.8 is connected to the output ports of the first and second hydraulic cylinders 11.1 and 11.2, respectively, via the return pipe of hydraulic oil pipeline 11.5, thus forming a closed hydraulic circulation loop.

[0075] Parallel servo control branches are located on the oil inlet of hydraulic oil pipeline 11.5, near the input ends of first hydraulic cylinder 11.1 and second hydraulic cylinder 11.2. Each servo control branch is equipped with a valve block 11.6. A servo valve 11.7 is fixedly mounted on the corresponding valve block 11.6. Together, they form a servo control assembly, which supplies the two hydraulic cylinders with hydraulic oil required for variable loads with set amplitude and frequency characteristics, thereby achieving dynamic adjustment and control of the loading amplitude, frequency, and direction.

[0076] Among them, the valve block 11.6 adopts one of the following typical structures: a superimposed valve block, a channel-type block structure, and a plug-in valve block, and the servo valve 11.7 adopts one of the two typical structures of a single-stage electro-hydraulic servo valve and a two-stage electro-hydraulic servo valve. The valve block 11.6 of the present application adopts a channel-type block structure, and the servo valve 11.7 adopts a two-stage electro-hydraulic servo valve structure. The valve block 11.6 is an integral block structure, which is internally provided with an oil inlet channel, an oil outlet channel and a connection interface for installing the servo valve 11.7, wherein the oil inlet channel is connected to the oil inlet of the servo valve 11.7, and the oil outlet of the servo valve 11.7 is connected to the input end of the hydraulic cylinder through the oil outlet channel of the valve block 11.6 through a servo control branch, and there is no bypass path between the oil inlet channel and the oil outlet channel, thereby ensuring that the oil must be regulated by the servo valve 11.7 before it can be output, thereby achieving complete control over the state of the oil entering the hydraulic cylinder. Servo valve 11.7 is used to guide part of the hydraulic oil to flow into servo valve 11.7 and output the regulated variable load hydraulic oil. The regulated variable load hydraulic oil naturally merges with the steady-state hydraulic oil in the oil inlet pipe of hydraulic oil pipeline 11.5 through the servo control branch, thereby changing the input oil pressure state entering the hydraulic cylinder and realizing dynamic interference control of loading direction, loading rate and load amplitude.

[0077] Servo valve 11.7 features mounting surfaces and screw holes for achieving a positional seal with valve block 11.6. It consists of a pre-stage control unit and a main-stage power control unit. The pre-stage unit is an electromagnetic nozzle-flapper structure that receives electrical control signals and outputs differential hydraulic pressure. The main-stage unit comprises a spool valve assembly, which drives the spool valve in response to the control pressure differential output by the pre-stage unit, thereby controlling the flow and direction of hydraulic oil output. A spool position sensor (such as an LVDT) is incorporated into the spool valve assembly for real-time feedback of spool displacement. The electrical control input of servo valve 11.7 is electrically connected to the system controller via a signal line. Based on a preset load signal (such as a sine wave, trapezoidal wave, or square wave), the controller outputs a corresponding voltage or current signal to servo valve 11.7, triggering the pre-stage control unit to generate a control pressure differential, which in turn drives the main-stage spool valve to move accordingly. This regulates the flow and pressure of hydraulic oil flowing through the hydraulic cylinder in the servo branch, resulting in a variable-load oil output with a set amplitude and frequency characteristic. The controller can form closed-loop control logic based on feedback signals (such as hydraulic cylinder displacement, load, or pressure sensor signals) to improve the servo system's response speed and control accuracy. The servo valve is the only control path for oil to flow to the hydraulic cylinder, and its degree of opening directly determines the output state of the servo control branch oil.

[0078] Hydraulic pump station 11.8 continuously outputs high-pressure, steady-state hydraulic oil, which is delivered to the two cylinders along the oil inlet pipe. When servo valve 11.7 is closed, the hydraulic oil does not flow through the servo branch, but flows directly from the hydraulic pump station through the main oil circuit to the two hydraulic cylinders. The system is in a constant pressure loading state, which is used to simulate the intermediate bearing's compliance under steady-state conditions. The output load (constant) of the first hydraulic cylinder 11.1 and the second hydraulic cylinder 11.2 is:

[0079] F 恒定 =A·P p

[0080] Oil pressure is constant: P c (t) = P p

[0081] Among them, P c (t) represents the oil pressure at the input end of the hydraulic cylinder; P p It represents the steady-state pressure output by the hydraulic pump station; A represents the effective pressure area of ​​the hydraulic cylinder piston.

[0082] In this constant load state, the motion of the first hydraulic cylinder 11.1 and the second hydraulic cylinder 11.2 satisfies the following second-order differential equation:

[0083]

[0084] in, They represent the equivalent inertia, damping, and elastic terms of the loading cylinder, respectively; M represents the equivalent mass of the loaded system (test shaft + intermediate bearing) (kg); C represents the damping coefficient (Ns / m); K represents the stiffness coefficient (N / m); x(t) represents the piston displacement (m), that is, the position of the hydraulic cylinder piston (changing with time); represents the first derivative, i.e., piston velocity (loading rate); represents the second-order derivative, i.e. acceleration (rate of change of piston motion); F 恒定 Indicates the load force output by the hydraulic cylinder (N); represents the additional load term (N) that characterizes the system friction, nonlinear disturbance, etc.

[0085] It should be noted that the nonlinear interference force term Characterizes the additional dynamic response deviation of the loading system during operation caused by factors such as structural friction, hydraulic cylinder leakage, nonlinear stiffness or damping, and clearance hysteresis. Its mathematical form can be modeled or identified based on actual system test data and supplemented as a disturbance term in the dynamic control model of the loading system to improve the simulation loading accuracy and system robustness. It can be fitted by test data. First, the control system is loaded with different amplitude / rate inputs, then the load-displacement-velocity data is measured, and finally the nonlinear residual term is fitted using regression methods such as least squares, neural networks, and support vector regression. For example, the difference between the actual load measured in the test and the theoretical term is expressed as:

[0086]

[0087] When servo valve 11.7 opens, a portion of the high-pressure hydraulic oil output from the hydraulic pump station is introduced into valve block 11.6 via a parallel servo control branch. Dynamic regulation occurs in the servo control assembly, causing changes in pressure or flow. This variable-pressure hydraulic oil then merges with the hydraulic oil in the main oil circuit at the hydraulic cylinder inlet, forming a composite oil flow with interference modulation characteristics. This alters the actual oil pressure entering the hydraulic cylinder, enabling precise control of loading direction, rate, and load amplitude. This is used to verify the quality of the intermediate bearing under dynamic loading conditions such as simulated ice excitation.

[0088] Since the servo control branch and the main oil circuit merge before the hydraulic cylinder inlet, the oil pressure P actually received by the first hydraulic cylinder 11.1 and the second hydraulic cylinder 11.2 is c (t) is:

[0089]

[0090] Among them, Q p Indicates the stable flow rate m output by the hydraulic pump station 3 / s, usually a constant; P pIndicates the constant pressure value Pa output by the hydraulic pump station; Q s (t) represents the time-varying flow in the servo branch (m 3 / s), that is, the flow rate at the output of the servo valve is controlled and adjusted, and is driven by the controller instruction to change; P s (t) represents the time-varying hydraulic pressure (Pa) output by the servo valve in the servo branch, that is, the dynamic oil pressure at the output end of the servo valve, including waveform modulation, such as sinusoidal disturbance.

[0091] This indicates that the hydraulic cylinder receives the superposition result of the steady-state pressure of the main oil circuit and the servo intervention oil flow, which has a time-varying characteristic.

[0092] Time-varying flow Q in the servo branch s (t) The opening of the servo valve is dynamically determined based on the pressure difference before and after the servo valve, and the hydraulic throttling formula is satisfied, specifically:

[0093]

[0094] Among them, C d Indicates the flow coefficient (about 0.6-0.8), characterizing the throttle structure and flow loss; The energy conservation constant when pressure energy is converted into kinetic energy, which is derived from the hydraulic throttling theory derived from the Bernoulli equation. v represents the flow rate; A(t) represents the valve opening area of ​​the servo valve (changing with time); ΔP(t) represents the pressure difference between the two ends of the valve, which is P p -P load (t), P p Indicates the steady-state pressure of the main oil circuit output by the hydraulic pump station, P load (t) represents the load side pressure of the servo valve, usually the hydraulic cylinder inlet pressure or back pressure; ρ represents the hydraulic oil density.

[0095] The relationship between the servo valve opening and the electrical signal is:

[0096] A(t)∝u(t)

[0097] Where u(t) is the controller input signal (such as sine wave, voltage, etc.).

[0098] Substituting into the throttling equation, we get:

[0099]

[0100] The flow rate is proportional to the input signal and varies nonlinearly with the pressure difference.

[0101] Assuming that the control voltage is u(t) = u0 + Δu·sin(2πft), the time-varying flow model Q under sinusoidal disturbance control is s (t) is:

[0102] Q s (t)≈Q0+ΔQ·sin(2πft)

[0103] Among them, Q0 represents the flow rate reference value, unit is m 3 / s, which is related to u0 and constant pressure ΔP; ΔQ represents the flow disturbance amplitude, unit is m 3 / s, Δu, and ΔP are functionally related; sin(·) represents a standard sinusoidal function that varies with time and is used to generate a periodic control signal or simulate a load disturbance waveform; 2πft represents the current phase of the sine wave, in radians (rad); f represents the number of repetitions of the periodic signal per second, in Hz (Hertz); and t represents the current moment, in seconds (s).

[0104] Due to the periodic impact between the blades and sea ice in the propeller propulsion system during ice excitation, the intermediate bearing is subjected to periodic force changes with the rotor, and the wave load in the navigation condition causes periodic structural vibration. Therefore, in the hydraulic loading control, sinusoidal disturbance is used as the control signal (or target output). Sinusoidal load can be precisely controlled in two dimensions: amplitude and frequency, thereby quantitatively simulating the mechanical response characteristics under dynamic environment. The servo valve output pressure P s (t) is a sinusoidal disturbance:

[0105] P s (t) = P0 + ΔP sin(2πft)

[0106] Among them, P s (t) represents the time-varying hydraulic pressure (Pa) output by the servo valve in the servo branch; P0 represents; ΔP represents; sin(2πft) represents;

[0107] The dynamic load response expressions of the first hydraulic cylinder 11.1 and the second hydraulic cylinder 11.2 are:

[0108]

[0109] Through the F(t) formula, variable load output with adjustable amplitude, frequency and waveform can be achieved.

[0110] During the whole process, the controller outputs a sine wave signal according to the set target or feedback signal, and the signal is adjusted by the servo valve to output P s (t), control branch pressure disturbance, branch hydraulic oil merges with the main oil circuit to generate a time-varying synthetic oil pressure P c (t), and then output the variable load F(t). The loading system still satisfies Newton's second law:

[0111]

[0112] The first and second hydraulic cylinders 11.1 and 11.2 are supplied with pressurized oil from the same hydraulic pump station 11.8, ensuring simultaneous loading on both sides and radially loading the test shaft 7 and intermediate bearing 8. Adjusting the hydraulic pump station output pressure precisely controls the loading oil pressure, thereby adjusting the radial force applied to both ends of the test shaft 7. The system supports continuously adjustable loading capacity within a range of 0–1000 kN and a frequency of 0–20 Hz, meeting the testing requirements of various intermediate bearing load conditions.

[0113] In the present application, the main oil circuit always provides stable high-pressure hydraulic oil as the basic load platform for loading. The parallel servo branch only introduces a small disturbance pressure oil, which naturally merges with the main oil circuit to form a high-stability background + controllable disturbance composite oil pressure, which will not cause system fluctuations or nonlinear response accumulation due to frequent responses. It is more suitable for test scenarios such as high-frequency vibration loading and fatigue simulation that require dynamic accuracy but require long-term stable operation. It has high stability and the basic oil pressure is not affected by frequent fluctuations of disturbances. The servo control branch is only responsible for "incremental loading", so that the controller only needs to regulate the changing part, which is conducive to building a more linear and faster-responding servo control model. After converging at the pressure synthesis point (hydraulic cylinder input end), the desired sinusoidal or other excitation signal is formed. The load waveform is smoother, and it is easier to achieve sinusoidal, step, and arbitrary waveform loading, reduce waveform distortion, improve control accuracy, and make disturbance characteristics more predictable. The servo valve does not bear the entire system pressure and flow output, only the output of the disturbing oil. The average flow rate and pressure differential are significantly reduced. The servo valve operates in a low-flow, low-pressure differential, high-frequency adjustment mode for a long time, which helps to reduce valve core wear, reduce heat and oil cavitation, reduce the servo valve load pressure, and extend its service life. In addition, the steady-state load and dynamic disturbance can be adjusted separately. The constant pressure pump station sets the base oil pressure (which determines the constant loading force), and the controller sets the servo valve frequency and disturbance amplitude (which determines the excitation characteristics). This facilitates the simulation of complex mixed load scenarios, such as the "base ballast + wave impact" superposition model, supports more complex environmental simulation needs, and enhances the system's versatility.

[0114] As the instruction manual Figure 5 , the intermediate bearing 8 also includes a housing connecting bolt 8.7, and the bearing housing consists of a bearing cover 8.1 and a bearing seat 8.2. The bearing seat 8.2 is fixedly mounted on the work platform by bolts to form a supporting infrastructure. The bearing cover 8.1 is firmly connected by the housing connecting bolt 8.7 arranged between it and the bearing seat 8.2, and the two together define an internal mounting cavity for mounting the bearing shell 8.3. The bearing shell 8.3 is assembled in the mounting hole formed by the bearing seat 8.2 and the bearing cover 8.1, and its inner surface is a semi-cylindrical curved surface structure that matches the test shaft 7, which is used to achieve axial covering and provide sliding fit support. The mounting hole has high machining accuracy to ensure that a reasonable radial gap is formed between the bearing shell 8.3 and the test shaft 7, so as to facilitate the entry of lubricating oil and maintain the dynamic pressure oil film state.

[0115] When the test shaft 7 is rotated by the drive system, it slides relative to the fixed bearing shell 8.3. The lubricating oil is drawn into the gap between the bearing shell and the shaft surface due to adhesion and drag on the rotating shaft surface. Due to the bearing structure design or the test load, a tiny convergent gap naturally forms between the shaft and the shell, forming a wedge-shaped oil wedge area. The lubricating oil enters the convergent gap area between the shaft and the shell under the adhesion and drag of the shaft surface, forming a wedge-shaped fluid channel. In this channel, the oil forms a pressure gradient due to relative motion and geometric constraints, generating a dynamic pressure field sufficient to support the center position of the shaft under external loading, thereby establishing a stable dynamic pressure lubrication state and achieving metal-free operation between the shaft and the shell.

[0116] The multi-point temperature monitoring system is used to monitor the temperature changes of key parts of intermediate bearing 8 in real time during the test to ensure its operation in a controlled thermal environment. The multi-point temperature monitoring system includes at least a first temperature sensor 8.5, a second temperature sensor 8.6, and temperature sensors installed at the input and output ends of cooling water coil 8.4.

[0117] Among them, the first temperature sensor 8.5 is installed on the bearing seat 8.2, and its sensing probe extends to the internal contact area of ​​the bearing shell 8.3. It is used to accurately detect the real-time temperature of the bearing shell in the operating state and reflect the trend of friction heat changes between the bearing shell surface and the test shaft 7. The bearing shell temperature is an important parameter for measuring the lubrication state and thermal load, and is a key basis for judging whether the bearing operation is stable. The second temperature sensor 8.6 is installed on the sealing plate 8.8 of the intermediate bearing 8, and its probe extends into the oil pool at the bottom of the bearing seat 8.2 to monitor the oil temperature in the lubricating oil pool. This temperature reflects the cooling effect of the oil film and the trend of changes in the oil viscosity, which is related to the stability of the dynamic pressure lubrication state and the load-bearing capacity of the oil film.

[0118] Cooling water coil 8.4 is installed in the oil sump at the bottom of bearing housing 8.2. Its structure surrounds the lubricating oil area, indirectly cooling the lubricating oil through continuous circulation of cooling water. Temperature sensors are installed at the input and output ends of the cooling water coil to monitor the inlet and outlet temperatures of the cooling water, respectively. Real-time monitoring of the temperature difference between the two ends helps evaluate the heat exchange efficiency and stability of the cooling system and provides a reference for adjusting the cooling water flow and temperature.

[0119] Through the multi-point arrangement and data fusion of the above-mentioned temperature monitoring system, full coverage monitoring of the temperature of key parts during the intermediate bearing test can be achieved, effectively supporting thermal balance analysis, fault warning and lubrication performance evaluation, and improving the intelligence level and test reliability of the test platform.

[0120] As the instruction manual Figure 6The cooling water circulation system 12 is used to effectively cool the oil in the lubricating oil pool within the intermediate bearing 8 to maintain the intermediate bearing's thermal stability during the loading test. The cooling water circulation system 12 includes a cooling water tank 12.1, a chiller 12.2, connecting pipes 12.3, and a flow meter 12.12.

[0121] Cooling water tank 12.1 is equipped with a cooling water pipe output end 12.4 and a cooling water tank input end 12.11, serving as a storage and primary water supply unit for the system's cooling water. A cooling water coil 8.4 is installed within intermediate bearing 8. This coil is located within the oil sump at the bottom of bearing seat 8.2 and provides indirect cooling of the lubricating oil. Cooling water coil 8.4 has a first input end 12.5, a second input end 12.6, and a first output end 12.7 and a second output end 12.8.

[0122] The cooling water pipe output end 12.4 is connected to the first and second input ends 12.5 and 12.6 of the cooling water coil via connecting pipe 12.3, respectively, to direct cooling water stored in cooling water tank 12.1 into cooling water coil 8.4. After flowing through the coil, the cooling water is discharged from the first and second output ends 12.7 and 12.8, where it is then combined through connecting pipe 12.3 and fed into the input end 12.9 of chiller 12.2.

[0123] Chiller 12.2, the core temperature control device, is responsible for cooling the cooling water after it absorbs heat from the coils. The cooled cooling water is then discharged from chiller output 12.10 and continues through connecting pipe 12.3 back to the cooling water tank input 12.11, completing a closed cooling water cycle.

[0124] During this circulation process, a flow meter 12.12 is installed on connecting pipe 12.3 to monitor the cooling water flow rate in real time. The system is also equipped with a control valve that adjusts the cooling water supply rate based on the detected flow rate, ensuring that the cooling water in cooling water coil 8.4 always flows at a stable rate.

[0125] When the cooling water circulation system 12 is in operation, cooling water tank 12.1 delivers cooling water at a predetermined temperature and flow rate to cooling water coil 8.4. Heat exchange between the coil and the lubricating oil effectively removes heat from the oil sump. The cooling water is heated after flowing through the coil, then cooled by chiller 12.2 before returning to the tank, forming a continuous and stable circulation system. After a period of operation, the system maintains the cooling water temperature within the set temperature range, providing intermediate bearing 8 with a constant temperature, controllable flow rate, and cooling medium.

[0126] Through the precise temperature control and flow regulation of the above-mentioned cooling water circulation system, the oil film instability caused by excessive temperature rise of the bearing lubricating oil can be prevented, providing reliable guarantees for the establishment and maintenance of the dynamic pressure lubrication environment, and improving the thermal control performance and test consistency during the intermediate bearing loading test.

[0127] As the instruction manual Figure 7 In the implementation of the present application, the test shaft 7 includes an intermediate shaft 7.1, connecting bolts 7.2 and a stepped shaft 7.3. The intermediate shaft 7.1 is the main part of the test shaft. It is a hollow cylindrical structure that is axially inserted into the bearing shell 8.3 of the intermediate bearing 8 to form a dynamic pressure lubrication fit with the bearing shell. The two ends of the intermediate shaft 7.1 are respectively connected to the stepped shafts 7.3 on both sides by connecting bolts 7.2. Each stepped shaft 7.3 is sleeved on the loading end of the corresponding first hydraulic cylinder 11.1 and the second hydraulic cylinder 11.2, and radial loading force transmission and angle compensation are realized specifically by the spherical roller bearing 11.4 installed on the top of the hydraulic cylinder.

[0128] The drive system is used to drive the test shaft 7 to operate at a specific speed to simulate the dynamic state of the intermediate bearing 8 in actual working conditions. The drive system includes a drive motor 2, a reduction gearbox 3, a first elastic pin coupling 4, a torque meter 5 and a second elastic pin coupling 6. The output shaft of the drive motor 2 is rigidly connected to the input shaft of the reduction gearbox 3 to achieve torque conversion from high speed to low speed. The output shaft of the reduction gearbox 3 is connected to the input shaft of the torque meter 5 through the first elastic pin coupling 4, which is used to absorb small vibrations and axial runouts of the system while transmitting torque. The torque meter 5 is used to monitor the transmission torque and speed data during the loading process in real time. Its output shaft is connected to the stepped shaft 7.3 at the first end of the test shaft 7 through the second elastic pin coupling 6, so as to effectively transmit the driving torque to the test shaft 7.

[0129] To prevent axial displacement of the test shaft 7 during loading and rotation, the present application further provides a thrust stop 9. The thrust stop 9 is fixedly mounted on the second working platform 10, with its top connected to the stepped shaft 7.3 at the second end of the test shaft 7. This provides axial limiting support to prevent axial movement of the test shaft 7 due to hydraulic loading or inertial forces, thereby ensuring the stability of the loading path and the bearing structure.

[0130] Furthermore, in order to realize the structural modularization and platform partitioning layout of the drive system and the loading system, the working platform consists of a first working platform 1 and a second working platform 10. The first working platform 1 is mainly used to install the equipment related to the drive system, specifically including: the drive motor 2, the reduction gearbox 3 and the torque meter 5, which are fixed on the first working platform 1 through the drive motor support 2.1, the reduction gearbox support 3.1 and the torque meter support 5.1 respectively, forming a complete power input module. The second working platform 10 carries the test part and the loading system, and is equipped with a thrust device 9, a hydraulic loading system 11, a cooling water circulation system 12 and a water tank 13. This split dual-platform structure is conducive to system assembly, test maintenance and modular adjustment, and also facilitates the rapid replacement and layout optimization of intermediate bearings of different structural sizes.

[0131] As the instruction manual Figure 8 Testing system 14 is used to control and monitor the loading performance of hydraulic actuators and includes a host computer 14.1, a display 14.2, a controller 14.3, a force sensor, an oil pressure sensor, and a supporting hydraulic control unit. These components communicate with each other via wired or bus connections, creating a hydraulic loading test platform with closed-loop control capabilities.

[0132] Host computer 14.1, the system's central processing unit, connects to controller 14.3 and is responsible for interpreting external input commands and transmitting control instructions to controller 14.3. It also receives sensor data for display on the human-machine interface and subsequent analysis. Display 14.2 is connected to host computer 14.1 to provide a human-machine interface. Operators can set loading parameters such as load and frequency using touchscreen or input devices, and monitor test data, system status, and fault alarms in real time. Controller 14.3, a key control node, establishes a real-time data exchange link with servo valve 11.7, force sensor, and oil pressure sensor via a signal bus to perform control logic calculations and issue execution instructions. Based on feedback data, controller 14.3 adjusts the servo valve control signal in real time to ensure that output parameters meet target values. Force sensors, mounted on the loading end or actuator of the hydraulic cylinder, measure the applied force during loading in real time and convert them into standardized signals for feedback to the controller. The force sensor must meet the requirements of fast dynamic response and high linearity to support frequency control. The oil pressure sensor is located in the hydraulic circuit of valve block 11.6 and monitors the current oil pressure in the hydraulic system, thereby assessing the system's pressure control accuracy and safety. Its signal is also fed back to controller 14.3 for closed-loop regulation.

[0133] During the operation of test system 14, the operator sets test parameters such as the target loading force and loading frequency via display 14.2. Host computer 14.1 receives these settings, converts them into standard control instructions, and transmits them to controller 14.3. Controller 14.3 controls servo valve 11.7 to adjust the hydraulic oil flow, pressure, and flow direction based on the target loading curve. The hydraulic oil drives the hydraulic cylinder to perform the loading action. During the loading process, the force sensor and oil pressure sensor respectively detect the applied force and oil pressure in real time. Controller 14.3 compares the sensor feedback with the target value in real time and dynamically adjusts the servo valve control signal using a PID or fuzzy control algorithm to achieve closed-loop correction. The control results and sensor data are synchronously transmitted back to the host computer and displayed on display 14.2, visualizing and controlling the test process.

[0134] The test system builds a complete closed-loop control structure by integrating the host, controller, servo control elements and dual feedback sensors. It can not only achieve high-precision control of the loaded load (including amplitude and frequency), but also respond to dynamic changes in the system in real time. It has good stability, responsiveness and repeatability, and is suitable for various hydraulic actuator performance testing scenarios.

[0135] As the instruction manual Figure 9 The present invention also describes a test method for a radial loading test bench for ship bearings that simulates ice load and immersion conditions, comprising the following steps:

[0136] Step 1: Install the intermediate bearing to be tested on the test platform so that it is sleeved on the test shaft. The bearing shell of the intermediate bearing and the test shaft form a sliding fit, and the water tank forms a sealed connection with the test shaft through the skeleton sealing structure.

[0137] Specifically, the intermediate bearing 8 to be tested is fastened and installed on the second working platform 10 by means of bolts, and the test shaft 7 is passed through the bearing shell 8.3 of the intermediate bearing from one end in sequence until the test shaft is fully in place. A water tank is installed on the outside of the intermediate bearing 8, so that the skeleton sealing structure of the test shaft 7 of the water tank forms a sealed connection with the test shaft. Then, the two ends of the test shaft 7 are placed in the spherical roller bearings 11.4 at the loading ends of the first hydraulic cylinder 11.1 and the second hydraulic cylinder 11.2. After the installation is completed, check whether the connecting bolts 7.2 between the intermediate shaft 7.1 and the stepped shafts 7.3 at both ends are firm, confirm that the connection parts are not loose or falling off, and that the test shaft as a whole is not stuck or floating in the axial direction. The fitting clearance meets the process tolerance requirements of the sliding bearing, ensuring that the test shaft can rotate smoothly and has the initial conditions for forming a dynamic pressure oil film.

[0138] Step 2: Start the cooling water circulation system, set the target temperature of the chiller, turn on the chiller and run the cooling water pump, and control the flow of cooling water by adjusting the outlet valve of the cooling water tank so that the cooling water enters the cooling water coil installed in the intermediate bearing at a predetermined flow rate to establish an oil pool cooling cycle.

[0139] Specifically, for cooling preparation, first activate the cooling water circulation system 12 and start the chiller 12.2. Based on the design and operating conditions of the intermediate bearing and the specified test environment, the target cooling water temperature should be set within a range of ≤36°C to ensure the appropriate lubricating oil viscosity while effectively removing heat generated by friction. Next, adjust the outlet control valve of the cooling water tank 12.1 to set an appropriate flow rate range. Depending on the diameter of the cooling water coil, a flow rate of 6–50 L / min is preferred to meet the dual requirements of cooling efficiency and flow rate stability.

[0140] Observe the flowmeter 12.12 installed on the connecting pipe 12.3 to confirm that the circulating water maintains a stable flow within the closed-loop system and is free of air blockage, oscillation, or back pressure. Also, ensure that the cooling water flows according to the designed path through the cooling water coil 8.4 at the bottom of the bearing housing to effectively cool the lubricating oil sump and control the oil sump temperature below 65°C, providing a good thermal foundation for forming a stable dynamic pressure oil film during operation.

[0141] Step 3: Start the drive motor and make the test shaft run stably at the preset speed through the reduction gearbox, torque meter and coupling. The test shaft is inserted into the intermediate bearing shell and forms a dynamic pressure lubrication state. Turn on the temperature monitoring system, activate the first temperature sensor arranged inside the bearing shell, the second temperature sensor arranged in the bearing oil pool, and the temperature sensors arranged at the water inlet and outlet ends of the cooling water coil, and establish a multi-point monitoring mechanism for the bearing shell temperature, lubricating oil temperature and cooling medium temperature.

[0142] Specifically, a torque meter is used to monitor the torque and speed of the test shaft in real time during operation, feeding this data back to the test system. As the test shaft rotates relative to the bearing, the lubricating oil, dragged along the shaft surface, enters the convergent gap between the shaft and the bearing, forming a wedge-shaped oil wedge. This wedge-shaped oil film, under the action of dynamic pressure, creates a stable, metal-to-metal lubrication state, supporting the external load.

[0143] Activate the multi-point temperature monitoring module of the system configuration, including the following subsystems:

[0144] The first temperature sensor 8.5 is mounted on the side wall of the bearing seat 8.2. The probe tip of the first temperature sensor 8.5 extends into the sliding contact area between the bearing shell 8.3 and the test shaft 7. It is used to monitor the surface temperature rise of the bearing shell due to frictional heat in real time, reflecting the transient thermal load and lubrication status of the intermediate bearing during operation.

[0145] The second temperature sensor 8.6 is located at the bow end seal plate 8.8. Its temperature probe is inserted into the bearing oil sump to monitor the overall temperature trend of the lubricating oil and evaluate the cooling system efficiency and oil film stability.

[0146] Temperature sensors are installed at the water inlet and outlet of the cooling water coil to measure the temperature change of the cooling water after entering and flowing through the cooling water coil, so as to calculate the heat carried away by the cooling water per unit time, thereby inferring the heat load of the oil pool.

[0147] After system startup, perform online testing on all temperature sensor signal channels to ensure stable operation, sensitive signal response, and the absence of short circuits, drift, or other anomalies. Archive the initial readings of each temperature channel as baseline temperature data for comparison with dynamic temperature curves during subsequent loading and operation. This initialization helps identify atypical temperature rise trends, provide trend warnings, and enable accurate thermal state analysis during testing.

[0148] Step 4: After the test shaft reaches the target speed, start the hydraulic loading system, close the servo valve, and output constant hydraulic oil to the first and second hydraulic cylinders through the hydraulic pump station to simulate steady-state stress conditions, or open the servo valve, and the controller outputs a control signal of set frequency and amplitude to the servo valve, driving the servo valve to adjust the oil flow and pressure in real time. The variable load hydraulic oil output by the servo control branch merges with the main oil circuit and flows into the hydraulic cylinder, causing the hydraulic cylinder to apply a symmetrical radial dynamic load of predetermined amplitude and frequency to the loading ends of both ends of the test shaft to simulate ice excitation load conditions.

[0149] Specifically, after the test shaft has stabilized and reached a preset speed, the hydraulic loading system is activated. The hydraulic loading system includes a hydraulic pump station, hydraulic oil pipelines, a valve block, a servo valve, a first hydraulic cylinder, a second hydraulic cylinder, and their supports. The hydraulic pump station outputs pressurized oil to the hydraulic oil pipeline and guides it to the first and second hydraulic cylinders, respectively. The first and second hydraulic cylinders are symmetrically mounted on the test platform via hydraulic cylinder supports. Spherical roller bearings are installed on top of the test shafts for connection to the stepped shafts at both ends of the test shaft. During the loading process, they automatically compensate for angular deviations of the test shaft to prevent eccentric loading. The hydraulic pump station provides constant hydraulic oil, and the servo valve regulates the flow and pressure of the main oil circuit in real time to achieve variable amplitude drive of the hydraulic cylinders. The pistons of the first and second hydraulic cylinders move synchronously, and the spherical roller bearings apply radial loads to both ends of the test shaft, which are then transmitted to the intermediate bearing via the test shaft, achieving radial loading of the intermediate bearing.

[0150] When the servo valve outputs a constant pressure signal, the hydraulic loading system applies a constant load to the intermediate bearing, simulating steady-state operating conditions. Specifically, when test shaft 7 reaches a preset speed, hydraulic pump station 11.8 is activated, controlling the hydraulic oil pressure to achieve a preset steady-state load. During the operation of test shaft 7, the lubricating oil temperature and bearing shell temperature of intermediate bearing 8 are monitored, and the compliance of intermediate bearing 8 is determined based on these temperatures.

[0151] Taking the simulated steady-state loading test as an example, the test process includes: installing the intermediate bearing to be tested inside the water tank of the test bench, ensuring that the test shaft passes through the bearing area of ​​the intermediate bearing, starting the cooling water circulation system, setting the cooling water temperature to 30°C and the flow rate to 40L / min to ensure good heat dissipation conditions in the lubricating oil pool. Starting the drive motor in the drive system to drive the test shaft to rotate at a constant speed of 160rpm. When the test shaft speed stabilizes, the hydraulic pump station in the hydraulic loading system is started, and the servo valve remains closed. The hydraulic pump station outputs hydraulic oil at a stable pressure (for example, 10MPa) to the first and second hydraulic cylinders. The two hydraulic cylinders apply symmetrical radial forces (for example, a loading force of 520kN) to the loading ends of the test shaft through spherical roller bearings. During the test, the bearing surface temperature and lubricating oil pool temperature are monitored in real time through multi-point temperature sensors. After the bearing temperature stabilizes, the bearing temperature is maintained at 68±2℃ and the lubricating oil temperature is maintained at 58±2℃. During the test, the temperature change data is analyzed to determine whether the temperature rise trend is stable and whether there are abnormalities such as overheating and oil film instability. If the temperature is controlled within a reasonable range and there is no vibration fluctuation during the loading process, it is determined that the intermediate bearing has qualified operating performance under steady-state loading conditions.

[0152] When the servo valve receives the controller's set frequency and amplitude control signals, it outputs a dynamically variable load to simulate alternating marine load environments such as ice excitation and wave impact. Specifically, when test shaft 7 reaches a preset speed, hydraulic pump station 11.8 is activated, and servo valve 11.7 is controlled by test system 14 to achieve the preset load amplitude and frequency. During the operation of test shaft 7, the lubricating oil temperature and bearing shell temperature of intermediate bearing 8 are monitored, and the intermediate bearing's compliance is determined based on these temperatures.

[0153] Taking the simulated ice-induced dynamic load test as an example, the test process involves installing the intermediate bearing in the test platform's water tank. The cooling system is set to a water temperature of 5°C and a cooling water flow rate of 40 L / min to simulate a low-temperature environment. The motor drives the test shaft at 160 rpm to ensure dynamic lubrication. The hydraulic loading system is activated, and the hydraulic pump station outputs a stable hydraulic source to the hydraulic circuit. The target load curve is set through the test system: the load amplitude is 360±160 kN and the frequency is 10 Hz. The controller transmits this command to the servo valve. A portion of the hydraulic oil flows through the servo control branch circuit to adjust the hydraulic oil pressure and flow in real time. The variable load hydraulic oil in the branch circuit changes the hydraulic oil load in the main circuit, which in turn drives the hydraulic cylinder piston to cyclically reciprocate, generating a sinusoidally varying symmetrical radial load. The dynamic load acts on both ends of the test shaft and is transmitted to the intermediate bearing through the test shaft. Throughout the dynamic loading process, temperature sensors collect bearing shell and oil sump temperature data. After the intermediate bearing temperature stabilizes, the bearing shell temperature fluctuation range is controlled within 70±2°C, and the lubricating oil temperature is controlled within 60±2°C. If there is no sudden rise in bearing temperature during the test, the lubricating oil does not fail, there is no sign of dry friction on the bearing shell, and the loading curve responds well, it is judged that the intermediate bearing has good impact resistance under dynamic working conditions, the sealing structure is intact, and the test result is qualified.

[0154] Step 5: Inject simulated water of a certain temperature and pressure into the water tank. Adjust the water pressure in the water tank through an external water pressure control system to establish the test conditions for the intermediate bearing in a ship's submerged service environment. Set the required water temperature through the water tank heating element, and use closed-loop regulation through the temperature control module to create a constant temperature immersion environment.

[0155] Specifically, a predetermined volume of simulated liquid is injected into the water tank through a water inlet located in the upper body of the water tank. The water tank consists of a lower and upper body connected by bolts to form a closed cavity. A skeleton seal and gland assembly are installed at the axial holes on both sides to ensure that the system maintains a good seal during operation after water filling and prevent leakage. The water tank is connected to an external hydraulic pressure control system, which connects a controllable air or water pressure source to the water tank through connecting pipes to set and adjust the liquid pressure inside the water tank. The system supports simulating hydrostatic pressures within the range of 0.1-0.5 MPa to reproduce the water depth environmental loads that the intermediate bearing may encounter during ship operation. Multiple distributed heating elements are installed inside the water tank, preferably resistance heating rods or coils. They are installed on the bottom or side walls of the water tank and are sheathed in stainless steel for corrosion and waterproofing. The heating elements are electrically connected to a temperature control module. The temperature control module includes a PT100 platinum resistance temperature sensor or thermocouple sensor and a PID thermostat to monitor the internal temperature of the water tank in real time and implement closed-loop control of the heating elements based on the feedback temperature data. The water temperature adjustment range is 5-50℃, and the temperature control accuracy is better than ±0.5℃, ensuring a stable constant temperature immersion environment.

[0156] The water tank temperature control module and the water pressure control system are integrated with a linkage interface, which can preset combined environmental parameters such as "constant water temperature + variable water pressure" or "constant water pressure + variable water temperature" according to different test conditions, thereby realizing the test environment simulation under multivariable marine service conditions.

[0157] Constant water temperature + variable water pressure is often used to simulate deep-water environments or other situations with large changes in water depth. It is applicable to deep-water environment simulation. When ship bearings, equipment or structures work in deeper waters (such as deep sea, deep-water ports, etc.), the water temperature is usually relatively constant, while the water pressure changes with the increase in water depth. At this time, the water temperature in the simulated environment should be kept constant (for example, seawater temperature), and the water pressure should be adjusted as the water depth changes. Deep-sea immersion test of ship bearings, for example, to simulate deep-sea navigation conditions, the bearing system may need to withstand different water pressures (for example, from 0.1MPa to 0.5MPa) at a constant temperature (such as 30°C). These changes in water pressure reflect the water depth or water pressure conditions in different sea areas.

[0158] Constant water pressure + variable water temperature is often used to simulate environments with drastic temperature fluctuations, or in certain real-world operating conditions where the water pressure remains constant but the water temperature fluctuates significantly. For example, in some marine environments, especially in tropical or polar regions, water temperature fluctuates significantly. In polar or high-latitude waters, water temperature may fluctuate seasonally, requiring constant water pressure while allowing the water temperature to vary based on experimental requirements. Alternatively, in a marine environment, a ship's intermediate bearing may experience significant temperature fluctuations while maintaining constant water pressure, such as seasonal variations in seawater temperature. In these cases, the water pressure remains constant, but the water temperature needs to be varied based on actual marine conditions.

[0159] Step 6: Temperature sensors installed inside the bearing, in the oil pool, and at the inlet and outlet of the cooling water coil are used to collect real-time data on the lubricating oil temperature, bearing temperature, and cooling water temperature during the operation of the intermediate bearing. The data is collected by the test system and then visualized and stored.

[0160] Step 7: During the loading process, the loading force and hydraulic pressure are monitored in real time through the force sensor and oil pressure sensor. The test system controller implements closed-loop adjustment of the servo valve control signal based on the feedback data to ensure that the loading curve meets the preset value. After the test, it is determined whether the intermediate bearing meets the performance indicators and sealing requirements based on the lubricating oil temperature, bearing temperature change trend and lubricating oil water content.

[0161] Specifically, force sensors are installed on both sides of the hydraulic loading system to monitor the radial load applied to both ends of the test shaft in real time. The force sensors are highly precise and can detect and provide feedback on even the smallest changes in the loading force, ensuring real-time force measurement and accurate response. Oil pressure sensors are installed in the output pipelines of the hydraulic pump station and the hydraulic cylinder oil circuits to monitor pressure changes in the hydraulic system in real time. These oil pressure sensors provide feedback on the pressure signal in the hydraulic system, ensuring that the hydraulic oil supply meets the loading requirements.

[0162] The collected loading force and hydraulic pressure data is transmitted to the test system's central processing unit (CPU) via a data acquisition system. The data processing module in the test system processes, stores, and analyzes the real-time data. The test system displays the current loading force and hydraulic pressure values ​​on a real-time display or via the data acquisition module, allowing operators to monitor the test status at all times and ensure that the loading force and pressure meet preset conditions.

[0163] Based on real-time collected loading force and oil pressure data, the test system controller adjusts the flow, pressure, and flow direction of the hydraulic oil via a servo valve, achieving precise control of the hydraulic cylinder. The controller utilizes a PID control algorithm (proportional-integral-differential control) to adjust the servo valve control signal in real time based on feedback from loading force and hydraulic pressure, ensuring that the hydraulic system's pressure and loading force consistently adhere to the preset loading curve. The servo valve's feedback control enables the hydraulic system to automatically correct for minor deviations caused by equipment wear, temperature fluctuations, or external disturbances, ensuring a stable and standardized loading force curve during testing.

[0164] During the loading process, the control system compares the target loading force with the actual feedback value in real time. If the actual loading force deviates from the preset value, the controller sends a signal to adjust the servo valve to ensure that the force value during the loading process remains within the specified range. Feedback data from the oil pressure sensor and force sensor not only ensures the accuracy of hydraulic loading but also detects any pressure anomalies or equipment failures in the hydraulic system, ensuring a safe test process.

[0165] Post-test data analysis and evaluation includes oil and bearing temperature analysis, lubricant moisture content monitoring, and performance and sealing assessment. After the test, the test system analyzes the oil and bearing temperature trends. By comparing the rate and stability of temperature changes, the system assesses the bearing's lubrication status and any risks of overheating or oil film instability.

[0166] During the test, the system continuously monitors the water content of the lubricating oil, collects the water content in the oil through a dedicated sensor, and combines data such as the lubricating oil temperature, bearing temperature and loading force to determine whether the lubricating oil is hydrated or contaminated.

[0167] Performance and sealing are determined based on all monitoring data (including lubricating oil temperature, bearing shell temperature trends, and lubricating oil water content). The system automatically generates a detailed evaluation report. This report helps engineers determine whether the intermediate bearing meets design requirements, meets performance indicators and sealing requirements, and possesses sufficient durability and reliability.

[0168] Step 8: If the intermediate bearing experiences abnormal temperature rise, abnormal oil temperature, or abnormal force loading during the test, the system will automatically issue an alarm command and shut down the hydraulic pump station and drive motor in sequence to terminate the test.

[0169] During the loading operation, if any of the following abnormal conditions are detected: any temperature parameter (bearing or lubricating oil temperature) exceeds the system-set threshold; mechanical anomalies such as severe vibration, abnormal noise, or load imbalance occur during the test shaft operation; cooling water temperature continues to rise, water flow decreases, or cooling system abnormality alarms occur; torque fluctuates frequently, or the drive system control feedback becomes unstable, the system immediately triggers a protection mechanism and performs the following emergency response operations: shutting down hydraulic pump station 11.8 to terminate loading on the test shaft; stopping drive motor 2 to cut off torque transmission; pausing the cooling water circulation system; locking all current real-time data such as temperature, torque, and pressure, and marking it as abnormal; the system enters fault analysis and diagnosis mode, prompting the operator to perform safety inspections and technical analysis. This abnormality handling mechanism effectively prevents damage to the intermediate bearing due to overheating, lubrication failure, or structural fatigue, enhancing the intelligence, safety, and long-term operational stability of the test system.

[0170] This test method has the advantages of high control accuracy throughout the entire process, realistic simulation of working conditions, support for multi-parameter adjustment, and a complete fault protection mechanism. It is suitable for the thermal-mechanical coupling performance evaluation and structural adaptability verification of various types of ship intermediate bearings.

[0171] The radial loading test bench and method for ship bearings of the present invention, which simulate ice loads and immersion conditions, ensure that the bearings operate within the optimal temperature range by accurately simulating seawater immersion and ice excitation loads, combined with a multi-point temperature monitoring system and a hydraulic loading system. Symmetrical radial dynamic loads can be applied to simulate bearing forces under different working conditions. The cooling water system effectively controls the temperature of the lubricating oil to avoid overheating. In addition, the test bench is equipped with an efficient data acquisition and feedback control system that can adjust the loading process and detect abnormal conditions in real time to ensure the accuracy and safety of the test. This system not only improves the authenticity and reliability of the test, but also provides data support for the design optimization of ship bearings and enhances the engineering application value and versatility of the test platform.

[0172] The above is only an embodiment of the present application, and common knowledge such as the specific structure and characteristics of the scheme are not described in detail here. For those skilled in the art, it is obvious that the present application is not limited to the details of the above-mentioned exemplary embodiments, and the present application can be implemented in other specific forms without departing from the spirit or basic characteristics of the present application. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-restrictive, and the scope of the present application is defined by the attached claims rather than the above description, and it is intended that all changes that fall within the meaning and scope of the equivalent elements of the claims are included in the present application. Any figure mark in the claims should not be regarded as limiting the claims involved.

Claims

1. A radial loading test method for ship bearings simulating ice load and immersion conditions, characterized in that: The ship bearing radial loading test method is implemented by a ship bearing radial loading test bench, the ship bearing radial loading test bench comprising a working platform, a multi-point temperature monitoring system, a test shaft (7), an intermediate bearing (8), and a drive system, a hydraulic loading system (11), a cooling water circulation system (12), a water tank (13) and a test system (14) installed on the working platform; the water tank (13) is provided with through axial holes on both sides, the intermediate bearing (8) is installed inside the water tank (13), and the water tank (13) is provided with a water tank heating element with a set temperature and a water body with pressure for simulating a seawater immersion condition; The intermediate bearing (8) includes a bearing housing, a bearing bush (8.3) and a cooling water coil (8.4); a cavity is provided in the bearing housing, and a mounting hole is provided axially through the cavity and the housing wall; the bearing bush (8.3) is installed in the mounting hole and forms a sliding fit with the test shaft (7); the cooling water coil (8.4) is provided in the oil pool area at the bottom of the bearing housing, and its water inlet and water outlet are respectively connected to the cooling water circulation system (12) for circulating and cooling the lubricating oil; The test shaft (7) is installed through the bearing (8.3), and its two ends pass horizontally through the shaft holes on both sides of the water tank (13). The output shaft of the drive system is connected to one end of the test shaft (7) to drive it to rotate; the hydraulic loading system (11) is symmetrically arranged on both sides of the intermediate bearing (8), and a loading end is provided on the top of the hydraulic loading system. The two ends of the test shaft (7) are respectively connected to the corresponding loading ends to apply a symmetrical radial load to the test shaft (7); the multi-point temperature monitoring system includes a plurality of temperature sensors, whose probes are respectively arranged inside the bearing (8.3) and in the oil pool area, for real-time monitoring of the bearing temperature and the lubricating oil temperature; The hydraulic loading system (11) comprises a first hydraulic cylinder (11.1), a second hydraulic cylinder (11.2), a hydraulic cylinder support (11.3), a spherical roller bearing (11.4), a hydraulic oil pipeline (11.5), a valve block (11.6), a servo valve (11.7) and a hydraulic pump station (11.8); the first hydraulic cylinder (11.1) and the second hydraulic cylinder (11.2) are symmetrically mounted on the working platform via the hydraulic cylinder support (11.3), and the top loading ends thereof are respectively provided with spherical roller bearings (11.4) that are matched with the connecting sleeves at both ends of the test shaft (7). 4) to apply a symmetrical radial load to the test shaft (7); the hydraulic oil pipeline (11.5) includes an oil inlet pipe and an oil return pipe, the first hydraulic cylinder (11.1) and the second hydraulic cylinder (11.2) are respectively provided with a hydraulic oil input end and an output end, the output end of the hydraulic pump station (11.8) is connected to the input ends of the first hydraulic cylinder (11.1) and the second hydraulic cylinder (11.2) via the oil inlet pipe, and the output ends of the first hydraulic cylinder (11.1) and the second hydraulic cylinder (11.2) are connected to the oil return port of the hydraulic pump station (11.8) via the oil return pipe, so as to form a closed hydraulic circulation loop; The oil inlet pipe is provided with a servo control branch in parallel at a position of the pipeline near the input end of the first hydraulic cylinder (11.1) and the second hydraulic cylinder (11.2), respectively. A valve block (11.6) is provided on the servo control branch. A servo valve (11.7) is fixedly mounted on the valve block (11.6). The servo valve (11.7) is used to receive an electrical signal output by a controller and adjust the flow rate and pressure of the hydraulic oil in the servo control branch to provide the first hydraulic cylinder (11.1) and the second hydraulic cylinder (11.2) with variable load hydraulic oil having set amplitude and frequency characteristics. The test system (14) includes a controller (14.3), and a force sensor and an oil pressure sensor connected to the controller (14.3) via a signal line. The force sensor is installed at the loading end of the hydraulic cylinder, and the oil pressure sensor is arranged on the hydraulic oil circuit of the valve block (11.6). The test method includes: Step 1: Install the intermediate bearing to be tested on the test platform so that it is sleeved on the test shaft. The bearing shell of the intermediate bearing and the test shaft form a sliding fit, and the water tank is sealed to the test shaft through the skeleton sealing structure. Step 2: Start the cooling water circulation system, set the target temperature of the chiller, turn on the chiller and run the cooling water pump. Control the cooling water flow by adjusting the outlet valve of the cooling water tank so that the cooling water enters the cooling water coil installed in the intermediate bearing at a predetermined flow rate, thus establishing the oil pool cooling cycle. Step 3: Start the drive motor and make the test shaft run stably at the preset speed through the reduction gearbox, torque meter and coupling. The test shaft is placed in the intermediate bearing bushing and forms a dynamic pressure lubrication state. Turn on the temperature monitoring system and activate the first temperature sensor set inside the bushing, the second temperature sensor arranged in the bearing oil pool, and the temperature sensors set at the water inlet and outlet of the cooling water coil. Establish a multi-point monitoring mechanism for the bearing bushing temperature, lubricating oil temperature and cooling medium temperature. Step 4: After the test shaft reaches the target speed, start the hydraulic loading system, close the servo valve, and output constant hydraulic oil to the first and second hydraulic cylinders through the hydraulic pump station to simulate steady-state stress conditions, or open the servo valve, and the controller outputs a control signal of set frequency and amplitude to the servo valve, driving the servo valve to adjust the oil flow and pressure in real time. The variable load hydraulic oil output by the servo control branch merges with the main oil circuit and flows into the hydraulic cylinder, causing the hydraulic cylinder to apply a symmetrical radial dynamic load of predetermined amplitude and frequency to the loading ends of both ends of the test shaft to simulate ice excitation load conditions. Step 5: Inject simulated water at a certain temperature and pressure into the water tank. Regulate the water pressure in the water tank using an external water pressure control system to establish the test conditions for the intermediate bearing in a ship's submerged service environment. Set the required water temperature using the water tank heating element, and then perform closed-loop regulation using the temperature control module to create a constant-temperature submersion environment. Step 6: Temperature sensors installed inside the bearing, in the oil pool, and at the inlet and outlet of the cooling water coil collect real-time data on the lubricating oil temperature, bearing temperature, and cooling water temperature of the intermediate bearing during operation. The data is collected by the test system and then visualized and stored. Step 7: During the loading process, the force sensor and oil pressure sensor monitor the loading force and hydraulic pressure in real time. The test system controller implements closed-loop adjustment of the servo valve control signal based on the feedback data to ensure that the loading curve meets the preset value. After the test, the lubricating oil temperature, bearing shell temperature change trend and lubricating oil water content are used to determine whether the intermediate bearing meets the performance indicators and sealing requirements. Step 8: If the intermediate bearing experiences abnormal temperature rise, abnormal oil temperature, or abnormal force loading during the test, the system will automatically issue an alarm command and shut down the hydraulic pump station and drive motor in sequence to terminate the test.

2. A test bench for implementing the ship bearing radial loading test method simulating ice load and immersion conditions as claimed in claim 1, characterized in that: The water tank (13) of the test bench comprises a water tank lower body (13.2) and a water tank upper body (13.5); the water tank lower body (13.2) is fixedly mounted on the working platform, and the water tank upper body (13.5) is mounted on the water tank lower body (13.2); the two together form a closed cavity structure.

3. The test bench for the ship bearing radial loading test method simulating ice load and immersion conditions according to claim 2 is characterized in that: The water tank (13) further comprises a skeleton seal (13.3) and a sealing gland (13.6); the skeleton seal (13.3) is installed at the axial hole of the water tank (13), and the sealing gland (13.6) presses the skeleton seal (13.3).

4. The test bench for the ship bearing radial loading test method simulating ice load and immersion conditions according to claim 2 is characterized in that: The test shaft (7) comprises an intermediate shaft (7.1), connecting bolts (7.2) and a stepped shaft (7.3); the intermediate shaft (7.1) is connected to the stepped shafts (7.3) at both ends via the connecting bolts (7.2).

5. The test bench for the ship bearing radial loading test method simulating ice load and immersion conditions according to claim 4 is characterized in that: It also includes a thrust device (9), which is installed on the second working platform (10), and the top of the thrust device (9) is connected to the stepped shaft (7.3) at the other end of the test shaft (7).

6. The test bench for the ship bearing radial loading test method simulating ice load and immersion conditions according to claim 4 is characterized in that: The drive system comprises a drive motor (2), a reduction gear box (3) and a torque meter (5); the output shaft of the drive motor (2) is connected to the input shaft of the reduction gear box (3), the output shaft of the reduction gear box (3) is connected to the input shaft of the torque meter (5), and the output shaft of the torque meter (5) is connected to the stepped shaft (7.3) at one end of the test shaft (7).

7. The test bench for the ship bearing radial loading test method simulating ice load and immersion conditions according to claim 2 is characterized in that: The cooling water circulation system (12) comprises a cooling water tank (12.1), a chiller (12.2), a connecting pipe (12.3), and a flow meter (12.12) arranged on the connecting pipe (12.3); the water inlet and the water outlet of the cooling water coil (8.4) are respectively connected to the cooling water tank (12.1) and the chiller (12.2) through the connecting pipe (12.3).

8. The test bench for the ship bearing radial loading test method simulating ice load and immersion conditions according to claim 2 is characterized in that: The working platform comprises a first working platform (1) and a second working platform (10), wherein the first working platform (1) is used for installing the drive system, and the second working platform (10) is used for installing the intermediate bearing (8), the hydraulic loading system (11) and the cooling water circulation system (12).

9. The test bench for the ship bearing radial loading test method simulating ice load and immersion conditions according to claim 2 is characterized in that: The bearing housing comprises a bearing cover (8.1) and a bearing seat (8.2); the bearing seat (8.2) is fixedly mounted on the working platform; the bearing cover (8.1) is connected to the bearing seat (8.2); the two together define an installation cavity for accommodating the bearing shell (8.3).

10. The test bench for the ship bearing radial loading test method simulating ice load and immersion conditions according to claim 9 is characterized in that: An oil pool for storing lubricating oil is provided at the bottom of the bearing seat (8.2), and the cooling water coil (8.4) is arranged inside the oil pool for cooling the lubricating oil in the oil pool.

Images