A nuclear main pump thrust bearing performance test system and method

Abstract

This invention discloses a performance testing system and method for nuclear main pump thrust bearings, relating to the field of nuclear power bearing technology. It includes a vertical frame structure mechanical body, a rotary drive system located at the bottom, a vertical transmission shaft, a bearing specimen with a thrust disc and upper and lower thrust bearing assemblies, an annular loading cylinder fitted around the transmission shaft and achieving bidirectional loading via a single cylinder, an oil circuit mechanism, and a measurement and control system for synchronous acquisition of multiple parameters. This invention adopts a coaxial compact layout, achieving bidirectional loading via a single cylinder. Performance testing of both upper and lower loading modes can be completed in a single clamping operation. Combined with the integrated control of the measurement and control system for drive, loading, and lubrication, it can cover various typical operating conditions of nuclear main pumps, including loaded, unloaded, and coasting conditions, ensuring the reliability of the testing process and the comprehensiveness of the test results.

Description

Technical Field

[0001] This invention relates to the field of nuclear power bearing technology, specifically to a nuclear main pump thrust bearing performance testing system and method. Background Technology

[0002] The main nuclear pump is a core power unit in the primary loop of a nuclear power plant. Its tilting pad thrust bearing bears the entire axial load of the unit's rotor and directly determines the safety and stability of the main pump under all operating conditions, including start-up, shutdown, steady-state operation, and emergency coasting. In situations such as loss of cooling water or a complete power outage, the thrust bearing will coast. However, when coasting into the low-speed range, interface oil depletion can easily occur, leading to increased friction and wear, and even bearing failure. This can prevent the main pump from restarting quickly, causing not only huge economic losses but also increasing the risk of reactor core meltdown. Therefore, before mass installation of thrust bearings, full-condition tribological performance testing is required on a dedicated test bench.

[0003] Existing technologies already include relevant testing devices. For example, Chinese Patent No. ZL202111493223.2 discloses a thrust bearing performance testing device based on similarity theory, which provides some technical inspiration in aspects such as scaled-down design, embedded bearing temperature measurement, mirror plate opening pressure measurement, and hydrostatic support. However, this device can only achieve unidirectional loading and cannot meet the testing requirements of bidirectional thrust bearings. Another example is Chinese Patent ZL202211385168.X, which discloses a nuclear power plant main pump thrust bearing test bench and its assembly method, which uses a motor, torque meter, loader, and bearing specimen along a vertical... The basic architecture of the axial arrangement has a bidirectional load-bearing structure, and it also proposes a technical idea of ​​achieving lubrication by driving the built-in pump through the rotation of the main shaft. However, this patent mainly involves the test bench assembly method and does not provide a complete bearing performance testing method, making it difficult to comprehensively evaluate the tribological characteristics of the thrust bearing. For example, Chinese patent CN105403408A discloses a bidirectional loading and bidirectional water-lubricated thrust bearing test device with preload. Its loading system adopts two independent hydraulic circuits, which is relatively complex in structure and is a water lubrication system, which is significantly different from the oil lubrication condition of the nuclear main pump thrust bearing.

[0004] In summary, existing scaled-down test benches generally suffer from problems such as a single loading method, incomplete simulation of working conditions, or lack of testing methods. They are unable to accurately reproduce the tribological behavior of the nuclear main pump thrust bearing under coasting, loaded, and unloaded conditions, which restricts the in-depth development of bearing design optimization and localization verification. Summary of the Invention

[0005] The purpose of this invention is to provide a nuclear main pump thrust bearing performance testing system and method. By adopting a vertical four-column structure and a single hollow annular oil cylinder to achieve bidirectional loading, and cooperating with an oil circuit mechanism to achieve lubricating oil circulation, and combined with a multi-parameter synchronous acquisition measurement and control system, this invention solves the problems of existing scaled-down test benches having a single loading method, incomplete working condition simulation, and inability to fully test the tribological performance of bidirectional thrust bearings.

[0006] To achieve the above-mentioned technical objectives, the present invention is implemented through the following technical solution: A nuclear main pump thrust bearing performance testing system includes: The main body of the machine is a vertical frame structure; A rotary drive system is located at the lower part of the mechanical body; A drive shaft is arranged along the vertical axis of the mechanical body and is connected to the rotary drive system for transmission. The bearing test piece, connected to the mechanical body, includes a thrust plate and upper thrust bearing assemblies and lower thrust bearing assemblies respectively disposed on both axial sides of the thrust plate, and the thrust plate is fixedly connected to the transmission shaft; A hydraulic loading system is installed on the upper part of the mechanical body, including an annular loading cylinder. The annular loading cylinder is sleeved on the outer periphery of the drive shaft. The annular loading cylinder applies an axial upward or downward loading force to the drive shaft through a single cylinder. The hydraulic system supplies lubricating oil to the bearing test piece and the annular loading cylinder. The measurement and control system is connected to the rotary drive system, the hydraulic loading system and the oil circuit mechanism for signal control of operation and acquisition of performance parameters of the bearing specimen.

[0007] In this scheme, a vertical frame structure with a vertical coaxial layout of lower rotary drive and upper hydraulic loading allows the annular loading cylinder to be fitted around the drive shaft and bidirectional loading of the drive shaft can be achieved with a single cylinder. At the same time, the cooperation between the thrust plate and the upper and lower thrust bearing assemblies located on both sides of it, and the fact that bidirectional loading can be completed by switching with the same cylinder, enables the system to complete bearing performance tests under both upward and downward loading modes under a single clamping condition, effectively expanding the working condition simulation range of the test bench. The measurement and control system controls the entire process of driving, loading and lubrication and collects multiple parameters synchronously, so that the system can still cover various typical working conditions of nuclear main pumps such as loaded, unloaded and coasting while simplifying the structure, ensuring the controllability of the test process and the comprehensiveness of the test results.

[0008] Furthermore, the thrust plate and the drive shaft are connected by a stop joint to ensure the coaxiality between the thrust plate and the drive shaft, and to provide a positioning basis for the uniform gap between the two end faces of the thrust plate and the upper and lower thrust bearing assemblies. This ensures that a stable dynamic pressure oil film is formed between the two axial end faces of the thrust plate and the upper and lower thrust bearing assemblies respectively during operation, avoiding wear and heat generation caused by direct metal-to-metal contact. The axial floating characteristic of the stop joint connection allows the thrust plate to move slightly axially with load changes, automatically adjusting the oil film thickness at both ends to dynamically match different loading directions and load magnitudes.

[0009] Furthermore, to ensure that each thrust bearing pad maintains a preset initial gap and angle with both ends of the thrust disk when static: the upper thrust pad assembly includes an upper thrust bearing seat, an upper support pad, an upper support pad support, and multiple upper thrust bearing pads. The upper thrust bearing pads are pressed against the upper thrust bearing seat and the thrust disk through the upper support pad and the upper support pad support. The lower thrust bearing assembly includes a lower thrust bearing housing, a lower support bearing, a lower support bearing support, and multiple lower thrust bearing bearing blocks. The lower thrust bearing blocks are pressed against the lower thrust bearing housing and the thrust disc through the lower support bearing and the lower support bearing support. Meanwhile, both the upper and lower support pads are tiltable support structures, allowing the thrust bearing pads to adaptively tilt slightly around the support point according to the load and speed during operation. This automatically adjusts the wedge angle between the working surface of the pad and the end face of the thrust disc, ensuring that each pad forms the optimal oil film wedge angle that matches the current working conditions. This results in a uniform and stable hydrodynamic pressure effect in each pad in the circumferential direction, effectively dispersing local oil film pressure peaks to the entire pad surface area and preventing pad surface burning or excessive wear caused by uneven loading. At the same time, the symmetrical upper and lower pressing pad layout, combined with the bidirectional loading function, ensures that the thrust pads on the corresponding sides are always in a stable pressed working state when the system is subjected to upward or downward loads.

[0010] Furthermore, the upper thrust bearing assembly also includes a positioning ring and a positioning pin. The positioning ring and the positioning pin fix the upper bearing support circumferentially, restricting the circumferential rotation of the upper bearing support. At the same time, they do not restrict the radial displacement and tilting degree of freedom of the bearing support, so that the thrust bearing pad can still adaptively tilt around the support point under load and speed to form the optimal oil film wedge angle.

[0011] Furthermore, the upper thrust bearing assembly also includes a spring and a side pressure block. The spring is disposed between the upper thrust bearing seat and the upper support bearing, and the side pressure block is disposed on the side of the upper support bearing. The spring and the side pressure block provide preload and lateral restraint for the upper support bearing to prevent circumferential movement of the bearing.

[0012] Furthermore, the oil circuit mechanism includes a viscous pump, which is disposed between the upper thrust bearing assembly and the lower thrust bearing assembly. The rotating part of the viscous pump is formed by the transmission shaft and / or the thrust disc itself, without the need for an independent impeller, an independent pump body and an independent drive source, so that the viscous pump is completely integrated into the bearing specimen without adding additional moving parts. The viscous pump is linked to the drive shaft. When the drive shaft starts, it synchronously drives the viscous pump to rotate, and when it stops, it stops synchronously, achieving complete synchronization between the lubricating oil circulation and the start and stop of the main shaft. At the same time, during the rotation of the viscous pump, the drive shaft itself drives the lubricating oil to flow, continuously exporting the hot oil generated by the friction of the bearing bush to the external cooler for heat dissipation. The cooled lubricating oil then flows back to the bearing specimen, forming a closed-loop cooling circuit to ensure that the lubricating oil always maintains a suitable working temperature during continuous operation.

[0013] Furthermore, to eliminate the interference of friction or inertial force in the intermediate transmission link on the measurement accuracy, the annular loading cylinder is connected to the upper support of the mechanical body, and a force sensor and a transition plate are arranged in sequence below the annular loading cylinder. The upper end of the force sensor is in contact with the annular loading cylinder, and the lower end of the force sensor is connected to the transition plate. The transition plate is connected to the drive shaft through a bushing and a pressure cap. The upward or downward loading force generated by the annular loading cylinder is transmitted to the drive shaft through the force sensor, the transition plate, the bushing, and the pressure cap. When the annular loading cylinder generates an upward loading force, the force sensor is in a compressed state. When the annular loading cylinder generates a downward loading force, the force sensor is in a stretched state, so that the force value measured in real time can truly reflect the actual axial load acting on the bearing specimen.

[0014] Furthermore, the number of the upper thrust bearing pads and the lower thrust bearing pads is at least 10 each, which effectively reduces the average specific pressure per unit area and avoids oil film rupture or excessive wear of the pad surface due to excessive local load.

[0015] Furthermore, in order to ensure that the test data can accurately reflect the actual tribological state of the working surface of the bearing, the measurement and control system includes an industrial computer, a programmable logic controller and a data acquisition module, and the performance parameters include at least one of the following: rotational speed, torque, loading force, displacement, oil film pressure, thrust bearing temperature and lubricating oil temperature and pressure. Meanwhile, temperature sensors are embedded in the upper thrust bearing pad and the lower thrust bearing pad respectively, so that the temperature of the pad body and the oil temperature near the pad surface can be obtained synchronously. Moreover, the sensor measurement point is close to the friction interface, and the measured temperature truly reflects the thermal state of the working surface of the pad. The bearing test piece is equipped with a pressure tapping tube, on which a pressure sensor is installed to extract and measure the oil film pressure at the center point of the pad. The pressure value obtained is most representative of the bearing's load-bearing capacity.

[0016] A method for testing the performance of a nuclear main pump thrust bearing, using a nuclear main pump thrust bearing performance testing system, includes the following steps: The oil circuit mechanism is activated to supply lubricating oil to the bearing specimen; The high-pressure jacking is activated, forming an oil film between the thrust disc and each thrust bearing pad. The rotary drive system drives the transmission shaft to rotate to a set speed. A predetermined loading force along the axial direction is applied to the drive shaft by the annular loading cylinder. The predetermined loading force is either an upward thrust or a downward pull. Under load operation, the performance parameters of the bearing specimen are collected by the measurement and control system; Stop loading, switch the rotary drive system to coasting stop mode, and decelerate the drive shaft to a stop according to a preset coasting curve; wherein, the preset coasting curve is the deceleration curve of the drive shaft speed changing with time after the driving force is cut off, and the rotary drive system automatically adjusts the speed reduction rate according to the current speed and the preset deceleration parameters.

[0017] In summary, compared with the prior art, the present invention has the following main advantages and beneficial effects: 1. This invention directly mounts a single annular loading cylinder onto the outer circumference of the drive shaft, allowing the loading force to be transmitted directly along the axis of the drive shaft. The loading path is extremely short and no intermediate conversion mechanism is required. Compared with the prior art, which requires two independent hydraulic circuits and two loading cylinders to achieve bidirectional loading, this invention eliminates the eccentric load problem that is easily caused by multi-cylinder loading. At the same time, by simplifying the hydraulic system structure, it also reduces the sealing links and leakage risks. 2. This invention directly constitutes the rotating parts of the viscous pump by the structure of the drive shaft and / or thrust plate itself, without adding any additional moving parts. Since the viscous pump is linked with the drive shaft, the start and stop are completely synchronized, avoiding the oil supply mismatch problem caused by the external motor driving the pump due to start-stop delay or advance. At the same time, the drive shaft itself is used to drive the lubricating oil circulation, continuously exporting the frictional hot oil for cooling. 3. This invention uses a positioning ring and a positioning pin to fix the bearing support circumferentially, effectively preventing the bearing from shifting circumferentially as the thrust disc rotates. At the same time, it retains radial and tilting degrees of freedom, allowing the bearing to adaptively tilt under load and speed to form the optimal oil film wedge angle. Meanwhile, the cooperation of the spring and the side pressure block also provides preload and lateral limit for the bearing, enabling the bearing to quickly establish an oil film at the moment of start-up, thus achieving a dynamic support effect. 4. This invention can achieve full operating condition coverage through a bidirectional loading cylinder: it can simulate three typical operating conditions of nuclear main pumps: no-load, loaded, and coasting. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings: Figure 1 This is a schematic diagram of a 1:4 scale test bench structure for the bidirectional thrust bearing of the nuclear main pump motor described in this invention. Figure 2 This is a cross-sectional structural diagram of the present invention; Figure 3 A schematic diagram of the upper support and the annular loading cylinder of the present invention.

[0019] Figure 4 This is a schematic diagram of the loader part of the present invention.

[0020] Figure 5 This is a schematic diagram of the internal cross-sectional structure of the bearing test chamber described in this invention.

[0021] Figure 6 This is a schematic diagram of the internal structure of the bearing specimen described in this invention.

[0022] Figure 7 This is a schematic diagram of the connection between the motor and the spindle described in this invention.

[0023] Figure 8 This is a schematic diagram of the viscous pump cavity structure described in this invention.

[0024] Figure 9 This is a schematic diagram of the bearing structure described in this invention.

[0025] The attached diagram shows the markings and corresponding component names: 1-Upper bracket, 2-Annular loading cylinder, 3-Loader housing, 4-Test bearing mounting box cover, 5-Test bearing mounting box, 6-Lower bracket, 7-Motor protective cover, 8-Servo motor, 9-Copper pad, 10-Brass pad, 11-Lifting ring, 12-Column, 13-Limiting pad, 14-Deep groove ball bearing, 15-Bolt, 16-Side bearing, 17-Sealing ring, 18-Force sensor, 19-Transition plate, 20-Stop, 21-Shaft sleeve, 22-Gland, 23-Silicon 24-Rubber pad, 25-Fan-shaped cover, 26-Locking ring, 27-Locking pin, 28-Upper thrust bearing pad, 29-Lower thrust bearing pad, 30-Lower bearing pad support, 31-Inner pressure ring, 32-Lower sealing ring, 33-PTFE gasket, 34-O-ring, 35-Upper thrust bearing housing, 36-Viscous pump, 37-Thrust disc, 38-Side pressure block, 39-Spring, 40-Lower thrust bearing housing, 41-Temperature sensor, 42-Pressure sensor, 43-Rigid coupling. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention. Example 1

[0027] This embodiment 1 provides a nuclear main pump thrust bearing performance testing system, such as... Figures 1-2 As shown, it includes the main mechanical body, rotary drive system, transmission shaft, bearing specimen, hydraulic loading system, oil circuit mechanism and measurement and control system.

[0028] Specifically, such as Figure 1 and Figure 2 As shown, the main body of the machine is a vertical frame structure. In a preferred embodiment, the main body is a vertical four-column structure, including an upper support 1, a lower support 6, and four columns 12. The upper support 1 and lower support 6 are integrally cast from HT250 steel, and the four columns 12 are made of D80 chrome-plated steel bars. The upper end of the upper support 1 is equipped with a lifting ring 11 (e.g., an M20 lifting ring) for hoisting. The lower support 6 is also connected to the bearing mounting housing 5 under test via hexagonal head screws, washers, and standard spring washers. A limiting pad 13 is also provided at the connection between the upper support 1 and the columns 12 to limit the axial displacement of the upper support 1 along the columns 12, preventing axial movement of the upper support 1 during loading.

[0029] Please refer to the following: Figure 1 and Figure 7The aforementioned rotary drive system is located at the lower part of the main body of the machine. This system includes a servo motor 8, which is vertically mounted on the bottom of the test bench. The servo motor 8 has a power of 90kW and is connected to a transmission shaft via a rigid coupling 43. The transmission shaft is positioned along the vertical axis of the main body of the machine. A motor protective cover 7 is provided outside the servo motor 8, and the cover 7 is connected to the lower support 6 via bolts 15, standard spring washers, and nuts. The servo motor 8 is directly axially mounted without a rotary reducer, and its speed is adjustable in both forward and reverse directions.

[0030] like Figure 2 and Figure 5 As shown, the bearing specimen is connected to the mechanical body and includes a thrust plate 37 and upper thrust bearing assemblies and lower thrust bearing assemblies respectively disposed on both sides of the thrust plate 37 along the axial direction. The thrust plate 37 is fixedly connected to the transmission shaft. As a preferred embodiment of this example, the thrust plate 37 is connected to the transmission shaft through a stop 20. The thrust plate 37 is installed in the middle of the transmission shaft and is the active rotating component of the friction pair, directly forming an oil film with the upper thrust bearing pad 28 and the lower thrust bearing pad 29.

[0031] Specifically, such as Figure 2 , Figure 5 and Figure 9 As shown, the upper thrust bearing assembly includes an upper thrust bearing housing 35, an upper support bearing 25, an upper support bearing support, and multiple upper thrust bearing pads 28. The upper thrust bearing pads 28 are positioned between the upper thrust bearing housing 35 and the thrust disc 37 via the upper support bearing 25 and the upper support bearing support. The upper thrust bearing housing 35 is fixed below the test bearing mounting box cover 4, positioned using a stop and installed with screws. The lower thrust bearing assembly includes a lower thrust bearing housing 40, a lower support bearing 29, a lower support bearing support 30, and multiple lower thrust bearing pads 29. The lower thrust bearing pads 29 are positioned between the lower thrust bearing housing 40 and the thrust disc 37 via the lower support bearing 29 and the lower support bearing support 30. The upper thrust bearing pad 28 and the lower thrust bearing pad 29 each consist of 10 pieces. Both the upper support pad and the lower support pad 30 are tiltable support structures, which allow the corresponding thrust bearing pads to tilt adaptively with load and / or rotational speed to form the optimal oil film wedge angle. This allows the axial forces between the two axial end faces of the thrust disc 37 and the upper thrust bearing pad 28 and the lower thrust bearing pad 29 respectively to be balanced by the hydrodynamic oil film.

[0032] In this embodiment, the upper thrust bearing assembly also includes a positioning ring 26 and a positioning pin 27 (e.g., a 20-φ3 positioning pin). The positioning ring 26 and the positioning pin 27 fix the upper support bearing circumferentially, restricting the circumferential rotation of the upper support bearing and retaining only radial and tilting degrees of freedom. Furthermore, the upper thrust bearing assembly also includes a spring 39 and a side pressure block 38. The spring 39 is disposed between the upper thrust bearing seat 35 and the upper support bearing 25, and the side pressure block 38 is disposed on the side of the upper support bearing 25. The spring 39 and the side pressure block 38 provide preload and lateral restraint for the upper support bearing 25, preventing circumferential movement of the upper thrust bearing pad 28. Similarly, the lower thrust bearing assembly also includes a lower positioning ring, a lower positioning pin, a lower spring, and a lower side pressure block, with a structure symmetrical to the upper thrust bearing assembly.

[0033] Specifically, such as Figure 1 and Figure 3 As shown, the bearing test housing 5 and the bearing test housing cover 4 together constitute the mounting cavity of the bearing test piece. The lower end of the bearing test housing 5 is connected to the upper end of the lower bracket 6. The bearing test housing cover 4 is installed above the bearing test housing 5. The bearing test housing cover 4 is installed above the bearing test housing 5 by means of hexagon socket head cap screws and O-ring seals 34. The lower end of the bearing test housing 5 is connected to the lower end cover by hexagon socket head cap screws and standard spring washers, and is also sealed by O-ring seals 34. A sector cover 24 is connected to the bearing test housing cover 4, which is also sealed by O-ring seals 34 and polytetrafluoroethylene gaskets 33. There is a silicone pad 23 between the sector cover 24 and the housing cover 4 for cushioning.

[0034] In this embodiment, as Figure 1 , Figure 3 and Figure 4As shown, the hydraulic loading system is located on the upper part of the machine body and includes a hollow annular loading cylinder 2, which is sleeved on the outer circumference of the drive shaft. The annular loading cylinder 2 selectively applies an axial upward or downward loading force to the drive shaft through a single cylinder. The annular loading cylinder 2 is connected to the upper support 1. Below the annular loading cylinder 2, a force sensor 18 and a transition plate 19 are arranged in sequence. The upper end of the force sensor 18 contacts the annular loading cylinder 2, and the lower end of the force sensor 18 is connected to the transition plate 19. The transition plate 19 is connected to the drive shaft through a bushing 21 and a pressure cap 22. The plane bearing 16 is placed in the middle of the loader housing 3. The pressure cover 22 is connected to the bushing 21 and is located at the lower end of the loader. A deep groove ball bearing 14 is installed at the upper end of the thrust shaft. A brass pad 10 separates the deep groove ball bearing 14 from the pressure cover 22. A copper pad 9 separates the lower end of the deep groove ball bearing 14. The upward or downward loading force generated by the annular loading cylinder 2 is transmitted to the drive shaft through the force sensor 18, the transition plate 19, the bushing 21, and the pressure cover 22. When the annular loading cylinder 2 generates an upward loading force, the force sensor 18 is in a compressed state. When the annular loading cylinder 2 generates a downward loading force, the force sensor 18 is in a stretched state.

[0035] At the same time, such as Figure 1 , Figure 5 and Figure 6 As shown, the oil circuit mechanism is used to supply lubricating oil to the bearing test piece and the annular loading cylinder 2. The oil circuit mechanism includes a viscous pump 36, a loading oil circuit, a loading lubricating oil circuit, a return oil circuit, and an oil storage container for storing lubricating oil. The viscous pump 36 is located between the upper thrust bearing assembly and the lower thrust bearing assembly, specifically installed between the upper thrust bearing housing 35 and the lower thrust bearing housing 40. The rotating parts of the viscous pump 36 are formed by the transmission shaft and / or the structure of the thrust disk 37 itself. It does not require an independent impeller and an independent pump body, and does not rely on blades or gears to do work. The viscous pump 36 is linked with the transmission shaft. When the transmission shaft drives the rotation, the viscous pump 36 drives the lubricating oil to circulate between the bearing test piece and the external cooler, carrying out the hot oil generated by the friction of the bearing bush, which is then cooled by the cooler and flows back. The oil-throwing structure (i.e., thrust head and oil baffle ring) of the viscous pump 36 rotates synchronously with the drive shaft, using centrifugal force to throw the viscous lubricating oil outward and guide it to the cooler inlet. Simultaneously, during the oil-throwing process, a local low-pressure zone is formed inside the pump chamber. Combined with the damping effect of the annular, narrow gap flow channel, external air cannot enter the pump chamber through the flow channel, thus creating a dynamic sealing effect to prevent lubricating oil leakage and air ingress. The loading oil circuit is used to deliver the lubricating oil in the oil storage container to the annular loading cylinder 2 to achieve loading of the annular loading cylinder 2. The loading lubrication oil circuit is used to deliver the lubricating oil from the oil storage container between the thrust plate 37 and the annular loading cylinder 2.

[0036] In this embodiment, the measurement and control system is connected to the rotary drive system, the hydraulic loading system, and the oil circuit mechanism for signal control of operation and acquisition of performance parameters of the bearing specimen. The measurement and control system includes an industrial computer (e.g., Advantech IPC 610L), a programmable logic controller (e.g., Siemens S7 PLC), and a data acquisition module. Performance parameters include at least one of the following: rotational speed, torque, loading force, displacement, oil film pressure, thrust bearing temperature, and lubricating oil temperature and pressure. Simultaneously, temperature sensors 41 (e.g., PT100 temperature sensors) are embedded in the upper thrust bearing pad 28 and the lower thrust bearing pad 29 to collect pad and oil temperatures. The measuring point of the temperature sensor 41 is 6mm from the pad surface, with a temperature range of 0-150℃ and a measurement accuracy of 0.1℃. The bearing specimen is also equipped with a pressure tapping tube, on which a pressure sensor 42 (e.g., HM91 miniature pressure sensor) is installed to extract and measure the oil film pressure at the center point of the pad. The pressure range is 0-5MPa, the measurement accuracy is 0.1%, and the temperature resistance does not exceed 85℃.

[0037] The measurement and control system also controls the rotary drive system to achieve three operating conditions: no-load operation, loaded operation, and coasting stop. Loaded operation includes upper loading mode drive and lower loading mode drive. The measurement and control system is set with warning values ​​and alarm values ​​for speed and torque. When the measured value exceeds the warning value, an audible and visual alarm is generated and the equipment does not stop. When the measured value exceeds the alarm value, an audible and visual alarm is generated and the equipment stops. The measurement and control system is also equipped with a hardware emergency stop button and a software emergency stop button. Example 2

[0038] like Figures 3 to 9 As shown, this embodiment provides the specific connection and positioning methods for the various components inside the bearing specimen.

[0039] In this embodiment, the test bearing mounting housing 5 and the test bearing mounting housing cover 4 constitute a closed cavity for the bearing test piece. The upper thrust bearing seat 35 is positioned by a stop and installed below the test bearing mounting housing cover 4 with screws. The upper thrust bearing pad 28 (made of Babbitt alloy) is fixed to the upper thrust bearing seat 35 by the upper support pad 25. The upper thrust bearing pad 28 is in direct contact with the upper surface of the thrust disc 37 and is the surface on which the hydrodynamic oil film is formed. The upper support pad support provides tilting support for the upper thrust bearing pad 28. The upper thrust bearing pad 28 is allowed to tilt adaptively with load and / or speed to form the optimal oil film wedge angle. The upper positioning ring 26 and positioning pin 27 fix the upper support pad in the circumferential direction, restricting the circumferential rotation of the upper support pad and retaining only radial and tilting degrees of freedom. The spring 39 is set between the upper thrust bearing seat 35 and the upper support pad 25 to provide preload for the upper support pad 25. The side pressure block 38 is set on the side of the upper support pad 25 to provide lateral limit for the upper support pad 25 and prevent the upper thrust bearing pad 28 from circumferentially moving.

[0040] Meanwhile, the lower thrust bearing housing 40 is fixed to the bottom of the bearing mounting box 5 under test, and the lower thrust bearing pad 29 is fixed to the lower thrust bearing housing 40 by the lower support pad. The lower thrust bearing pad 29 is in direct contact with the lower surface of the thrust disc 37. The lower support pad support 30 provides tiltable support for the lower thrust bearing pad 29, allowing the lower thrust bearing pad 29 to tilt adaptively with load and / or speed. The lower positioning ring and lower positioning pin fix the lower support pad support 30 circumferentially, restricting the circumferential rotation of the lower support pad support 30, retaining only radial and tilting degrees of freedom. The lower spring is set between the lower thrust bearing housing 40 and the lower support pad, providing preload to the lower support pad; the lower side pressure block is set on the side of the lower support pad, providing lateral limit to the lower support pad, preventing the lower thrust bearing pad 29 from circumferentially moving.

[0041] The thrust disc 37 is installed in the middle of the drive shaft and connected to the drive shaft through the stop 20. The axial end faces of the thrust disc 37 are balanced with the upper thrust bearing pad 28 and the lower thrust bearing pad 29 respectively by a hydrodynamic oil film. The inner pressure ring 31 is set inside the bearing specimen to press the relevant components. The lower sealing ring 32 and the O-ring 34 are used for sealing the various connection parts. The PTFE gasket 33 is set at the connection of the sector cover 24. The silicone gasket 23 is set between the sector cover 24 and the housing cover 4 for cushioning.

[0042] The viscous pump 36 is installed between the upper thrust bearing housing 35 and the lower thrust bearing housing 40, and drives the lubricating oil circulation through the rotation of the drive shaft. The viscous pump 36 has no independent impeller or dedicated pump body; it does not rely on blades or gears for work, but instead utilizes the drive shaft and the structure of the thrust disc 37 itself as the rotating components of the pump. Figure 8 As shown, the outer edge of its annular narrow gap flow channel forms a narrow annular gap with the oil sump baffle ring and the oil sump wall, serving as an oil flow transport channel. The gap is uniform and fixed, and the viscous pump 36 has its own oil throwing and guiding structure (thrust head, oil baffle ring) to throw the viscous oil outward and guide it to the cooler inlet. When the oil throwing structure of the viscous pump 36 rotates synchronously with the drive shaft, it uses centrifugal force to throw the lubricating oil outward, while forming a local low-pressure area inside the pump cavity. Combined with the damping effect of the annular narrow gap flow channel, it prevents external air from entering the pump cavity through the flow channel, thus forming a dynamic sealing effect. Since the viscous pump 36 is integrated with the thrust bearing, it does not require a motor or coupling. It rotates synchronously with the drive shaft, has no separate moving mechanism, a simple flow channel, no valve plunger, and only annular gap and guide baffle inside. Example 3

[0043] This embodiment provides a method for testing the performance of a nuclear main pump thrust bearing, based on Embodiment 1 or Embodiment 2, to investigate the tribological properties of bearing specimens under an upward loading mode, including the following steps: Step S1: Start the oil circuit mechanism to supply lubricating oil to the bearing test piece; press the "Lubricating Oil Pump Start / Stop" button on the control panel to control the operation of the oil pump, so that the lubricating oil is delivered through the loading lubricating oil circuit to the thrust plate 37 and the annular loading cylinder 2, and the viscous pump 36 starts circulating lubricating oil before the drive shaft starts, to ensure that the surfaces of each friction pair inside the bearing test piece are fully lubricated before starting.

[0044] Step S2: Start the high-pressure lifting to form an oil film between the thrust plate 37 and each thrust bearing pad. To prevent dry friction between the upper thrust bearing pad 28, the lower thrust bearing pad 29 and the thrust plate 37 when the servo motor 8 starts, a high-pressure lifting operation must be performed before starting. Press the "High-Pressure Lifting" button on the control panel to slightly lift the thrust plate 37 with high-pressure oil, so that an initial stable oil film is formed between the two axial end faces of the thrust plate 37 and the upper thrust bearing pad 28 and the lower thrust bearing pad 29 respectively, thereby avoiding excessive wear of the pad surface due to boundary lubrication at the moment of start-up.

[0045] Step S3: Drive the transmission shaft to the set speed via the rotary drive system; open the software settings interface of the measurement and control system, input the spindle speed (e.g., 1485 rpm), acceleration, deceleration, and other parameters required for the test, and confirm and save the settings to ensure they take effect. When setting parameters, strictly adhere to the rated parameter range of the equipment to avoid exceeding the range and damaging the servo motor 8; after confirming the parameters take effect, start the servo motor 8. The servo motor 8 drives the transmission shaft to rotate via the rigid coupling 43, which in turn drives the thrust disk 37 to rotate synchronously. The speed measurement is acquired through the motor encoder, and the measurement and control system displays and records the current speed value in real time.

[0046] Step S4: Apply a set axial loading force to the drive shaft through the annular loading cylinder 2. The set loading force is a downward force. In the software parameter setting interface of the measurement and control system, input the set loading force value of the annular loading cylinder 2 (e.g., 26969N), and select the upward loading mode. After the parameter setting is completed, confirm that it takes effect. After confirming that the lubricating oil circulation is normal, press the "Loading Start" button on the control panel to start the annular loading cylinder 2. The upward loading force generated by the annular loading cylinder 2 is transmitted to the drive shaft through the force sensor 18, transition plate 19, bushing 21 and pressure cover 22, and then transmitted to the thrust plate 37 through the drive shaft. The upper end face of the thrust plate 37 and the upper thrust bearing pad 28 bear the upward load through a dynamic pressure oil film. During the loading process, observe the loading force value on the software interface of the measurement and control system in real time to confirm that it rises steadily to the set value without significant fluctuations. At the same time, check that the annular loading cylinder 2 has no leakage, abnormal noise or other abnormalities.

[0047] Step S5: Under load operation, the performance parameters of the bearing specimen are collected through the measurement and control system; the specimen is continuously operated under a set loading force and a set speed, and after the operating state stabilizes (e.g., temperature change does not exceed 1℃ / 5min), the performance parameters of the bearing specimen are synchronously collected and recorded through the measurement and control system. The performance parameters include at least one of the following: speed, torque, loading force, displacement, oil film pressure, thrust bearing temperature, and lubricating oil temperature and pressure. Temperature sensors 41 (PT100 temperature sensors) embedded in the upper thrust bearing pad 28 and the lower thrust bearing pad 29 respectively collect the temperature of each pad and the oil temperature in real time; pressure sensors 42 installed on the pressure tapping pipe collect the oil film pressure at the center point of the pad in real time; force sensor 18 collects the loading force value in real time and uses it as a feedback signal for closed-loop control.

[0048] Step S6: Turn off the servo motor 8 to stop the drive shaft from rotating. After the test is completed, while the test bench is under load, press the "Load Stop" button on the control panel to stop the loading operation of the annular loading cylinder 2; export the operating data recorded by the measurement and control system to obtain the test results such as the average temperature of the upper thrust bearing pad 28 and the lower thrust bearing pad 29 being 69.4℃ and 56.4℃ respectively, the average oil temperature being 65.2℃, the average friction coefficient being 0.0014, and the average oil film pressure being 2.66MPa, providing data support for the tribological performance evaluation of the nuclear main pump thrust bearing. Example 4

[0049] This embodiment provides another method for testing the performance of the nuclear main pump thrust bearing. For the bearing performance test under no-load operation, the specific test method includes the following steps: Step S1: Start the oil circuit mechanism to supply lubricating oil to the bearing test piece; press the "Lubricating Oil Pump Start / Stop" button on the control panel to control the operation of the oil pump, so that the lubricating oil is delivered through the loading lubricating oil circuit to the thrust plate 37 and the annular loading cylinder 2.

[0050] Step S2: Start the high-pressure lifting to form an oil film between the thrust plate 37 and each thrust bearing pad; press the "high-pressure lifting" button on the control panel to slightly lift the thrust plate 37 with high-pressure oil, so that the two axial end faces of the thrust plate 37 form an initial stable oil film between the upper thrust bearing pad 28 and the lower thrust bearing pad 29 respectively.

[0051] Step S3: Drive the transmission shaft to rotate to the set speed through the rotary drive system; open the software settings interface of the measurement and control system, input the spindle speed (e.g., 1485 rpm), acceleration, deceleration and other parameters required for the test, confirm and save after setting the parameters and make them effective, start the servo motor 8, the servo motor 8 drives the transmission shaft to rotate through the rigid coupling 43, and the transmission shaft drives the thrust disk 37 to rotate synchronously.

[0052] Step S4: Apply a set axial loading force to the drive shaft through the annular loading cylinder 2; in the software parameter setting interface of the measurement and control system, input the set loading force value of the annular loading cylinder 2 (e.g., 8000N), and select the corresponding loading mode (drop-down loading). After the parameter setting is completed, confirm that it takes effect. After confirming that the lubricating oil circulation is normal, press the "Load Start" button on the control panel to start the annular loading cylinder 2; the loading force generated by the annular loading cylinder 2 is transmitted to the drive shaft through the force sensor 18, transition plate 19, bushing 21 and pressure cover 22, and then transmitted to the thrust plate 37 through the drive shaft. The corresponding end face of the thrust plate 37 and the thrust bearing pad on the corresponding side bear the load through the dynamic pressure oil film.

[0053] Step S5: Under no-load operation, collect the performance parameters of the bearing specimen through the measurement and control system; after the operation is stable, collect and record the performance parameters of the bearing specimen synchronously through the measurement and control system.

[0054] Step S6: After stopping the loading, stop the drive shaft from rotating. After the test is completed, while the test bench is under load, press the "Load Stop" button on the control panel to stop the loading operation of the annular loading cylinder 2. Export the operating data recorded by the measurement and control system to obtain test results such as the average temperatures of the upper thrust bearing pad 28 and the lower thrust bearing pad 29 being 53.7℃ and 54.9℃ respectively, the average oil temperature being 54.9℃, the average friction coefficient being 0.0015, and the average oil film pressure being 0.51MPa. These results provide data support for the tribological performance evaluation of the nuclear main pump thrust bearing. Example 5

[0055] This embodiment provides another method for testing the performance of the nuclear main pump thrust bearing. For the bearing performance testing method in coasting stop mode, the specific testing method includes the following steps: Step S1: Start the oil circuit mechanism to supply lubricating oil to the bearing test piece; press the "Lubricating Oil Pump Start / Stop" button on the control panel to control the operation of the oil pump, so that the lubricating oil is delivered through the loading lubricating oil circuit to the thrust plate 37 and the annular loading cylinder 2.

[0056] Step S2: Start the high-pressure lifting to form an oil film between the thrust plate 37 and each thrust bearing pad; press the "high-pressure lifting" button on the control panel to slightly lift the thrust plate 37 with high-pressure oil, so that the two axial end faces of the thrust plate 37 form an initial stable oil film between the upper thrust bearing pad 28 and the lower thrust bearing pad 29 respectively.

[0057] Step S3: Drive the transmission shaft to rotate to the set speed through the rotary drive system; open the software settings interface of the measurement and control system, input the spindle speed (e.g., 1485 rpm), acceleration, deceleration and other parameters required for the test, confirm and save after setting the parameters and make them effective, start the servo motor 8, the servo motor 8 drives the transmission shaft to rotate through the rigid coupling 43, and the transmission shaft drives the thrust disk 37 to rotate synchronously.

[0058] Step S4: Apply a set axial loading force to the drive shaft through the annular loading cylinder 2; in the software parameter setting interface of the measurement and control system, input the set loading force value of the annular loading cylinder 2 (e.g., 26969N), and select the corresponding loading mode (upward loading). After the parameter setting is completed, confirm that it takes effect. After confirming that the lubricating oil circulation is normal, press the "Loading Start" button on the control panel to start the annular loading cylinder 2; the loading force generated by the annular loading cylinder 2 is transmitted to the drive shaft through the force sensor 18, transition plate 19, bushing 21 and pressure cover 22, and then transmitted to the thrust plate 37 through the drive shaft. The corresponding end face of the thrust plate 37 and the thrust bearing pad on the corresponding side bear the load through the dynamic pressure oil film.

[0059] Step S5: Under load operation, collect the performance parameters of the bearing specimen through the measurement and control system; after the operation is stable, collect and record the performance parameters of the bearing specimen synchronously through the measurement and control system.

[0060] Step S6: Switch the rotary drive system to coasting stop mode, causing the drive shaft to decelerate to a stop according to the preset coasting curve. In the software settings interface of the measurement and control system, switch the stop mode to "Formula Coasting Stop" and click the "Coasting Stop" button next to the motor mode selection. The servo motor 8 will automatically adjust its speed to complete the coasting stop according to the preset formula and the current speed. The coasting formula is 682.341*exp(-x / 11.385)+668.748*exp(-x / 59.226)+103.689. The preset coasting curve is the deceleration curve of the drive shaft's speed over time after the driving force is cut off. The servo motor 8 automatically adjusts the speed reduction rate according to the current speed and the preset deceleration parameters. During the coasting stop process, the measurement and control system continuously collects and records the changes in performance parameters such as speed, torque, oil film pressure, and thrust bearing temperature to analyze the lubrication characteristics and thermal response behavior of the thrust bearing under power-off coasting conditions.

[0061] Step S7: Stop loading; After the test is completed, when the test bench is in the loading state, press the "Loading Stop" button on the control panel to stop the loading operation of the annular loading cylinder 2.

[0062] Exporting the operational data recorded by the measurement and control system can yield dynamic change curves of various performance parameters during the coasting stop process, providing experimental basis for the safety assessment of the nuclear main pump thrust bearing under accident coasting conditions.

[0063] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A nuclear main pump thrust bearing performance testing system, characterized in that, include: The main body of the machine is a vertical frame structure; A rotary drive system is located at the lower part of the mechanical body; A drive shaft is arranged along the vertical axis of the mechanical body and is connected to the rotary drive system for transmission. The bearing test piece is connected to the mechanical body and includes a thrust plate (37) and an upper thrust bearing assembly and a lower thrust bearing assembly respectively disposed on both sides of the thrust plate (37) along the axial direction. The thrust plate (37) is fixedly connected to the transmission shaft. The hydraulic loading system is located on the upper part of the mechanical body and includes an annular loading cylinder (2). The annular loading cylinder (2) is sleeved on the outer periphery of the transmission shaft. The annular loading cylinder (2) applies an axial upward loading force or a downward loading force to the transmission shaft through a single cylinder. The oil circuit mechanism supplies lubricating oil to the bearing test piece and the annular loading cylinder (2); The measurement and control system is connected to the rotary drive system, the hydraulic loading system and the oil circuit mechanism for signal control of operation and acquisition of performance parameters of the bearing specimen.

2. The nuclear main pump thrust bearing performance testing system according to claim 1, characterized in that, The thrust disc (37) is connected to the transmission shaft through a stop (20). In operation, the two axial end faces of the thrust disc (37) form dynamic pressure oil films with the upper thrust bearing assembly and the lower thrust bearing assembly, respectively.

3. The nuclear main pump thrust bearing performance testing system according to claim 1, characterized in that, The upper thrust bearing assembly includes an upper thrust bearing seat (35), an upper support (25), an upper support, and multiple upper thrust bearing pads (28). The upper thrust bearing pads (28) are pressed between the upper thrust bearing seat (35) and the thrust disc (37) by the upper support (25) and the upper support. The lower thrust bearing assembly includes a lower thrust bearing seat (40), a lower support, a lower support support (30), and multiple lower thrust bearing pads (29). The lower thrust bearing pads (29) are pressed between the lower thrust bearing seat (40) and the thrust disc (37) by the lower support and the lower support support (30). Both the upper bearing support and the lower bearing support (30) are tiltable support structures, allowing the corresponding thrust bearing pads to tilt adaptively with load and / or rotational speed.

4. The nuclear main pump thrust bearing performance testing system according to claim 3, characterized in that, The number of the upper thrust bearing pad (28) and the lower thrust bearing pad (29) is at least 10 each. The tiltable support structure cooperates with each thrust bearing pad to form a uniformly distributed hydrodynamic oil film in the circumferential direction.

5. The nuclear main pump thrust bearing performance testing system according to claim 4, characterized in that, The measurement and control system includes an industrial computer, a programmable logic controller and a data acquisition module. The performance parameters include speed, torque, loading force, displacement, oil film pressure, thrust bearing temperature and at least one of lubricating oil temperature and pressure. Temperature sensors (41) are embedded in the upper thrust bearing pad (28) and the lower thrust bearing pad (29) respectively to collect the pad temperature and oil temperature; the bearing test piece is provided with a pressure tapping tube, and a pressure sensor (42) is installed on the pressure tapping tube to measure the oil film pressure at the center point of the pad.

6. The nuclear main pump thrust bearing performance testing system according to claim 3, characterized in that, The upper thrust bearing assembly and / or lower thrust bearing assembly further includes a positioning ring (26) and a positioning pin (27), the positioning ring (26) and the positioning pin (27) fixing the upper thrust bearing support and / or lower thrust bearing support circumferentially and restricting the circumferential rotation of the thrust bearing support.

7. The nuclear main pump thrust bearing performance testing system according to claim 3, characterized in that, The upper thrust bearing assembly and / or lower thrust bearing assembly further includes a spring (39) and a side pressure block (38). The spring (39) is disposed between the upper thrust bearing seat (35) and the upper support bearing (25), and the side pressure block (38) is disposed on the side of the upper support bearing (25). The spring (39) and the side pressure block (38) provide preload and lateral restraint for the upper support bearing (25).

8. The nuclear main pump thrust bearing performance testing system according to claim 3, characterized in that, The oil circuit mechanism includes a viscous pump (36), which is disposed between the upper thrust bearing assembly and the lower thrust bearing assembly, and the rotating part of the viscous pump (36) is formed by the transmission shaft and / or the thrust disc (37) itself. The viscous pump (36) is linked to the drive shaft. When the drive shaft is driven to rotate, it drives the lubricating oil to circulate between the bearing test piece and the external cooler.

9. The nuclear main pump thrust bearing performance testing system according to claim 1, characterized in that, The annular loading cylinder (2) is connected to the upper support (1) of the mechanical body, and a force sensor (18) and a transition plate (19) are arranged in sequence below the annular loading cylinder (2). The upper end of the force sensor (18) is in contact with the annular loading cylinder (2), and the lower end of the force sensor (18) is connected to the transition plate (19). The transition plate (19) is connected to the drive shaft through the bushing (21) and the pressure cap (22). The upward or downward loading force generated by the annular loading cylinder (2) is transmitted to the drive shaft through the force sensor (18), the transition plate (19), the bushing (21) and the pressure cap (22).

10. A method for testing the performance of a nuclear main pump thrust bearing, comprising the nuclear main pump thrust bearing performance testing system as described in any one of claims 1 to 9, characterized in that, Includes the following steps: The oil circuit mechanism is activated to supply lubricating oil to the bearing specimen; The high-pressure lifting is activated, forming an oil film between the thrust plate (37) and each thrust bearing pad; The rotary drive system drives the transmission shaft to rotate to a set speed. A set loading force along the axial direction is applied to the transmission shaft by the annular loading cylinder (2), and the set loading force is an upward pushing force or a downward pulling force; Under load operation, the performance parameters of the bearing specimen are collected by the measurement and control system; Stop loading, switch the rotary drive system to coasting stop mode, and decelerate the drive shaft to a stop according to a preset coasting curve; wherein, the preset coasting curve is the deceleration curve of the drive shaft speed changing with time after the driving force is cut off, and the rotary drive system automatically adjusts the speed reduction rate according to the current speed and the preset deceleration parameters.

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