A virtual in-situ testing device and method for dynamic lubrication characteristics of a distribution pair

Abstract

The present invention discloses a simulated in-situ testing device and method for the dynamic lubrication characteristics of a distribution pair. A set of pseudo-plunger and slipper assemblies is designed. Through friction conversion, the effects of friction and leakage caused by the plunger and slipper assemblies are stripped away, thereby achieving independent measurement of the friction torque and leakage flow of the distribution pair. At the same time, the design structure of the distribution pair based on the residual clamping force method is retained, which can realistically simulate the actual dynamic load-bearing and lubrication state of the distribution pair, and achieve in-situ measurement of the motion characteristics of the multi-degree-of-freedom overturning of the cylinder body. The present invention provides an important experimental basis for analyzing the distributed dynamic lubrication characteristics of the distribution pair. It only requires modification on the existing plunger pump, retaining the original core rotating component structure such as the cylinder body, plunger, and slipper, and is simple to process and low in cost.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydraulic pumps, and in particular relates to a simulated in-situ testing device and method for dynamic lubrication characteristics of a distribution pair. Background Art

[0002] Axial piston pumps are hydraulic pumps that use the reciprocating motion of the piston within the cylinder bore to change the volume within the piston chamber to achieve oil suction and discharge. Compared to other positive displacement pumps, they offer advantages such as high power density, high efficiency, and long service life, making them widely used in engineering machinery, aerospace, mobile robotics, and other fields. The distribution pair formed by the rotating cylinder block and the port plate is a critical friction pair in the piston pump. Friction loss and leakage flow are the main sources of mechanical and volumetric losses in the piston pump. Therefore, establishing a test device to study the dynamic load-bearing lubrication mechanism of the distribution pair is crucial for guiding the optimal design of the piston pump.

[0003] The design of the valve pair widely utilizes a "residual clamping force" approach. The high-pressure oil in the plunger cavity creates a clamping force that presses the cylinder body against the valve plate. Simultaneously, the high-pressure oil forms an extremely thin hydraulic film within the valve pair gap, generating a hydraulic support force that attempts to push the cylinder body apart. While most of the clamping force is balanced by the oil film, a small residual force remains to press the cylinder body against the valve plate, ensuring that the cylinder body remains pressed against the valve plate without disengaging. This unique "residual clamping force" design approach enables the valve pair to perform the multiple functions of load bearing, sealing, and lubrication.

[0004] Among currently used, published, or authorized patents, there are two main methods for testing the oil film of the distribution pair: one based on real pump modifications (such as an online testing device for oil film characteristics of a hydraulic pump distribution pair based on end cover modification, ZL115076089A), and the other based on model pumps (such as a comprehensive testing device for the distribution pair of a plunger pump, ZL110836178A). Test devices based on real pump modifications are limited by the pump's limited installation space, and only a limited number of sensors, such as eddy current sensors and thermocouples, can be installed on the rear end cover of the distribution plate. Furthermore, the distribution pair in a real pump is affected by the plunger pair and the slipper pair, making it impossible to independently measure the friction torque and leakage flow of the distribution pair. Many test setups based on simulated pumps approximate the valve pair to a simple ring-disc friction pair. However, in actual operation, plunger pumps are inevitably subject to impact loads, including rapid starts and stops and frequent reversing. The cylinder bottom cannot maintain an ideal parallel position with the valve plate surface, but instead undergoes multi-degree-of-freedom micro-motion, causing the oil film to constantly undergo dynamic adjustment. Therefore, while this method is simple, it does not adhere to the residual compressive force design method and cannot truly simulate the dynamic load-bearing characteristics of the valve pair oil film. Summary of the Invention

[0005] The purpose of the present invention is to address the deficiencies in the prior art and provide a simulated in-situ testing device and method for the dynamic lubrication characteristics of a distribution pair, thereby providing an important experimental basis for analyzing the distributed dynamic lubrication characteristics and failure mechanism of the distribution pair.

[0006] The present invention provides a simulated in-situ testing device for the dynamic lubrication characteristics of a distribution pair, which is realized by the following technical solution: a simulated in-situ testing device for the dynamic lubrication characteristics of a distribution pair, the device comprising a rotating component and a transmission component;

[0007] The rotating component consists of a cylinder body, a distribution plate, a pseudo plunger shoe assembly, an eddy current sensor, a ball joint, a center spring, and a plunger cavity sealing plug; the pseudo plunger shoe assembly is embedded in the corresponding cylinder hole of the cylinder body, and the plunger cavity sealing plug is installed at the bottom of the cylinder hole with an interference fit; the center spring is pre-compressed and embedded in the cylinder body, pressing the ball joint toward the return plate on one side and the cylinder body toward the distribution plate on the other side. The back of the distribution plate is tightly fitted with the rear end cover, and radial displacement is constrained by the positioning pin; three eddy current displacement sensors are installed on the outer circle of the distribution plate at a 120° angle to each other.

[0008] The pseudo plunger and shoe assembly comprises a plunger, a shoe, a return plate, and a rotating support plate, connected as a whole by a set of screws; each pair of plungers and shoes is hinged together by a ball head and a ball socket; the shoe is pressed against the surface of the rotating support plate with a zero inclination design by the action of high-pressure oil in the plunger chamber; the return plate is fixed to the rotating support plate and clamps the outer circle of the shoe to limit the axial displacement of the shoe;

[0009] The transmission component consists of a main shaft, angular contact ball bearings, needle roller bearings and an oil seal; the main shaft runs through the entire rotating assembly, drives the cylinder body to rotate through a spline pair, and is supported on the front and rear end covers by needle roller bearings and angular contact ball bearings at both ends respectively. The oil seal is installed between the main shaft and the front end cover with an interference fit to seal the leaked oil in the housing.

[0010] Furthermore, the plunger cavity sealing plug is provided with an O-ring to form a radial seal with the cylinder hole. The high-pressure oil is sealed by the plunger cavity sealing plug. The high-pressure oil will neither leak from the plunger pair gap to the housing, nor leak from the slipper pair gap into the housing through the damping hole of the plunger slipper, thereby eliminating the leakage loss of the plunger pair and the slipper pair from the source. The gear flowmeter is used to directly measure the leakage flow in the housing, which is the leakage flow of the distribution pair.

[0011] Furthermore, the test device also includes a shell component, which consists of a shell, a front end cover, a rear end cover and a compression-torsion composite sensor, which are connected to each other by a bolt array; the compression-torsion composite sensor adopts a double flange structure, the outer ring is fixed to the shell, and the inner ring is connected to the rear end cover, while realizing direct measurement of axial force and friction torque; the friction torque of the distribution pair interface directly acts on the surface of the distribution plate, and the distribution plate and the rear end cover are axially compressed and circumferentially constrained, and the friction torque is transmitted to the compression-torsion composite sensor through the distribution plate and the rear end cover.

[0012] Furthermore, the high and low pressure oils introduced into the oil port of the rear end cover are diverted through the waist groove of the distribution plate and enter the plunger cavity from the waist groove of the cylinder body; the axial load generated by the high pressure oil acts on the bottom of the cylinder body, generating an axial clamping force to press the cylinder body toward the distribution plate.

[0013] Furthermore, under the combined action of the pressure difference between the inside and outside of the distribution pair sealing belt and the relative movement of the matching parts, the oil is brought into the gap of the distribution pair to form an oil film, isolating the matching parts and forming a stable oil film static pressure support to balance the external load force; at this time, the cylinder body undergoes microscopic multi-degree-of-freedom overturning, generating dynamic pressure effect, extrusion effect and solid micro-contact to balance the residual clamping force of the static pressure support, thereby achieving dynamic force balance of the distribution pair.

[0014] Furthermore, three eddy current displacement sensors with an angle of 120° to each other are installed on the rear end cover. By measuring the oil film thickness at three non-collinear points on the bottom surface of the cylinder, the oil film thickness at any point and the overturning angle and overturning direction of the cylinder can be determined.

[0015] Furthermore, the ratio of the static pressure support force on the cylinder body generated by the oil film pressure of the distribution window and the sealing belt to the axial compression force generated by the high-pressure oil is defined as the balance coefficient. The axial compression force under this balance coefficient makes the cylinder body always press against the distribution plate without falling off.

[0016] Furthermore, the rear end cover is respectively provided with a first annular wiring groove and a second annular sealing groove. The three eddy current sensor wires are reasonably arranged through the first annular wiring groove and extend from the axial end of the rear end cover to avoid damage to the sensor wires; the second annular sealing groove 1b is installed with an O-ring to prevent oil from leaking from the inside of the housing to the outside, thereby ensuring the reliability and sealing of the measurement.

[0017] Furthermore, a measuring disk is installed on the outer edge of the cylinder body, and the bottom is flush with the mating surface of the cylinder body. The eddy current sensor probe is parallel to the plane of the measuring disk, and an appropriate gap is left. The measured surface of the measuring disk is more than twice the diameter of the probe, the radial distance of the metal material around the sensor is more than 1.5 times the diameter of the probe, and the distance between the two sensors is more than 6 times the diameter of the probe.

[0018] On the other hand, the present invention also provides a virtual in-situ testing method of a virtual in-situ testing device based on the dynamic lubrication characteristics of a distribution pair, the method comprising the following steps:

[0019] (1) The main shaft cooperates with the driving cylinder to drive the pseudo plunger sliding shoe assembly to rotate, so that the distribution pair is in dynamic force balance;

[0020] (2) The axial force and friction torque are measured based on the compression-torsion composite sensor, and the leakage flow in the shell is measured by the gear flowmeter, which is the leakage flow of the distribution pair;

[0021] (3) The overturning posture of the cylinder and the oil film thickness field of the distribution pair are determined by measuring the oil film thickness at three non-collinear points on the bottom surface of the cylinder.

[0022] The beneficial effects of the simulated in-situ testing device for the dynamic lubrication characteristics of the distribution pair proposed in the present invention are:

[0023] 1. Compared with the previous test transposition based on real pumps, the present invention designs a set of pseudo plunger and slipper assemblies. Through friction conversion, it completely removes the effects of friction and leakage brought by the plunger pair and slipper pair, and realizes the direct measurement of the friction torque and leakage flow of a single distribution pair.

[0024] 2. Compared with the previous test transposition based on the model pump, the present invention retains the design structure of the distribution pair based on the residual clamping force method, can truly simulate the actual dynamic load-bearing and lubrication state of the distribution pair, and realizes the in-situ measurement of the motion characteristics of the multi-degree-of-freedom overturning of the cylinder body.

[0025] 3. The present invention only requires modification of the existing plunger pump, retaining the original core rotating component structures such as the cylinder body, plunger, and sliding shoe, which is simple to process and low in cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is an overall axonometric drawing of the present invention;

[0027] Figure 2 It is an overall cross-sectional view of the present invention;

[0028] Figure 3 Schematic diagram of the core rotating assembly;

[0029] Figure 4 It is the core part of the friction torque measurement of the distribution pair.

[0030] Figure 5 Schematic diagram of the compression-torsion composite sensor;

[0031] Figure 6 It is the core part of the dynamic oil film clearance measurement of the distribution pair;

[0032] Figure 7This is a schematic diagram of the installation of the eddy current sensor;

[0033] Reference numerals:

[0034] 1. Rear end cover, 1a. Wiring groove, 1b. Sealing groove, 1c. High and low pressure oil ports, 2. Pressure sensor, 3. Compression-torsion composite sensor, 3a. Compression-torsion composite sensor inner ring, 3b. Compression-torsion composite sensor outer ring, 4. Housing, 5. Distribution plate, 5a. Distribution plate sealing strip, 5b. Distribution plate waist groove, 6. Measuring plate, 7. Plunger cavity sealing plug, 8. Plunger, 9. Slipper, 10. Angular contact ball bearing, 11. Front end cover, 12. Oil seal, 13. Spindle, 14. Rotating support plate, 15. Return plate, 16. Ball joint, 17. Center spring, 18. Cylinder block, 19. Needle roller bearing, 20. Eddy current sensor. DETAILED DESCRIPTION

[0035] The present invention is achieved through the following technical solutions:

[0036] like Figure 1 and Figure 2 As shown, in one embodiment, the present invention provides a simulated in-situ testing device and method for the dynamic lubrication characteristics of a distribution pair. Its main working principle is: a set of pseudo-plunger and sliding shoe assemblies are designed, which, through friction conversion, completely eliminate the effects of friction and leakage brought by the plunger and sliding shoe assemblies, thereby achieving independent measurement of the friction torque and leakage flow of the distribution pair. At the same time, the residual clamping force design structure of the distribution pair is retained, simulating the real dynamic load-bearing and lubrication characteristics of the distribution pair, and achieving in-situ monitoring of the multi-degree-of-freedom overturning characteristics of the cylinder body. The specific structure is as follows:

[0037] The test device's housing consists of the following parts. The housing 4, front cover 11, and outer ring 3b of the compression-torsion composite sensor are connected to each other via an array of bolts, with O-rings installed between the mating surfaces for sealing. The rear cover 1 extends from the center circular hole of the inner ring 3a of the compression-torsion composite sensor and is bolted together. An O-ring is installed in a sealing groove 1b on the back of the rear cover 1 to seal the wiring groove 1a. High- and low-pressure flow channels 1c are opened inside the rear cover 1, and a pressure sensor 2 is threadedly mounted on the side of the rear cover 1 to measure the pressure of the high- and low-pressure oil ports 1c.

[0038] The rotating part of the test device consists of the following parts. Figure 3As shown, the cylinder bore of cylinder block 18 contains an odd number of plungers 8, spaced evenly around the circumference. A plunger cavity sealing plug 7 is inserted into the bottom of the cylinder bore with an interference fit, sealing the bore and plunger 8 assembly. Each pair of plungers 8 and a sliding shoe 9 is hingedly connected via a ball joint and socket. The sliding shoe 9 is pressed against the surface of a rotating support plate 14 by the high-pressure oil in the plunger cavity. A return plate 15 is fixed to the rotating support plate 14 with screws, gripping the outer circumference of the sliding shoe 9 to limit axial displacement. The plungers 8, sliding shoes 9, return plate 15, and rotating support plate 14 are mutually constrained, forming a pseudo-plunger and sliding shoe assembly. The rotating support plate 14 has an interference fit with the main shaft 13, while the angular contact bearing 10 has a clearance fit with the rotating support plate 14, bearing both axial and radial loads. The center spring 17 is embedded in the center cavity of the cylinder 18. After being pre-compressed, the center spring applies force to both sides. On the one hand, it presses the ball joint 16 toward the return disk 15. On the other hand, the cylinder 18 is tightly pressed against the upper surface of the distribution disk 5 through the retaining spring. The back of the compressed distribution disk 5 fits tightly against the rear end cover 1, and the radial displacement is constrained by the positioning pin. Three eddy current displacement sensors 20 are installed on the outer circle of the distribution disk. The eddy current displacement sensors 20 are at an angle of 120 degrees to each other and are fastened in the threaded holes of the rear end cover 1. The transmission of the sensor is first led out through the wiring groove 1a on the back of the end cover 1. The measuring disk 6 is installed on the outer edge of the cylinder 18 by fastening screws. The bottom of the measuring disk 6 is flush with the mating surface of the cylinder. The eddy current sensor probe is parallel to the plane of the measuring disk, with an appropriate gap left.

[0039] The transmission components of the test device consist of the following parts. The main shaft 13 runs through the entire rotating assembly of the device. The external splines of the main shaft 13 are loosely coupled with the internal splines of the cylinder body 18, driving the cylinder body 18 to rotate. The rear end is supported on the rear end cover 1 via a needle roller bearing 19, while the front end is supported on the front end cover 10 via an angular contact ball bearing 10. An oil seal 12 is installed between the main shaft 13 and the front end cover 11 with an interference fit to seal any oil leaks within the housing.

[0040] The friction and leakage caused by the plunger pair and the sliding shoe pair can be eliminated by the following methods. Figure 3 As shown, during operation, the plunger 8, slipper 9, return plate 15, and rotating support plate 14 are connected together by a set of screws to form a pseudo-plunger and slipper assembly. The main shaft 13 drives the cylinder body 18 through a splined fit, causing the pseudo-plunger and slipper assembly to rotate. The rotating support plate 14 adopts a zero-angle design, eliminating the need for the plunger 8 to reciprocate and extend within the cylinder bore, and the slipper 9 to slide relative to the rotating support plate 14. This eliminates friction losses caused by the plunger 8 and slipper 9 assembly. Furthermore, an O-ring is provided on the plunger cavity sealing plug 7 to form a radial seal with the cylinder bore. High-pressure oil is sealed by the plunger cavity sealing plug 7, preventing it from leaking into the housing through the plunger assembly clearance or leaking into the housing through the slipper assembly clearance through the damping holes in the plunger 8 and slipper 9. This eliminates leakage losses from the plunger and slipper assemblies at the source.

[0041] The design of retaining the residual clamping force of the distribution pair is achieved in the following way. The distribution pair structure is subjected to a force analysis. The high and low pressure oils are introduced through the oil port of the rear end cover 1c, and are diverted through the waist groove 5b of the distribution plate, and enter the plunger cavity from the waist groove of the cylinder body. The axial load generated by the high pressure oil passes through the plunger cavity sealing plug 7, plunger 8, sliding shoe 9 and rotating support plate 14, and is finally transmitted to the angular contact ball bearing. On the other hand, it acts on the bottom of the cylinder body 18, generating an axial clamping force to press the cylinder body 18 toward the distribution plate 5. The axial clamping force F on the cylinder body 18 is clamp And the overturning moment M caused by the imbalance of high and low pressure sides tilt As shown in the following formula:

[0042] (1)

[0043] (2)

[0044] Where z is the number of plungers, d p is the plunger cavity diameter, R p is the radius of the plunger distribution circle, F s is the central spring force, θ n is the angular displacement of the nth plunger. n is the oil pressure in the nth plunger cavity, and its expression is as follows:

[0045] (3)

[0046] Where p H is the oil pressure of the high-pressure oil circuit, p L The oil pressure in the low-pressure oil circuit. Under the combined effect of the pressure difference between the inside and outside of the distribution pair sealing belt and the relative movement of the cylinder body 18 and the distribution plate 5, oil with a certain viscosity is brought into the gap of the distribution pair to form an oil film, isolating the paired parts and forming a stable oil film static and dynamic pressure support to balance the external load force. At the same time, the pressure reduction and throttling effect of the gap oil film prevents the oil in the plunger cavity from leaking into the housing. The static pressure support force F on the cylinder body is generated by the oil film pressure of the distribution window and the sealing belt. hydrostatic and anti-overturning moment M hydrostatic As shown in the following formula:

[0047] (4)

[0048] (5)

[0049] Where R1 and R2 are the inner and outer radii of the inner seal, R3 and R4 are the inner and outer radii of the outer seal, respectively. HThe static pressure support formed by the gap flow between the distribution plate 5 and the cylinder body 18 can offset most of the axial compression force. The ratio of the static pressure support force to the axial compression force is defined as the balance coefficient B. b , written as:

[0050] (6)

[0051] In the residual clamping force design method, the balance coefficient is usually taken as 0.95~1, that is, about 5% of the clamping force makes the cylinder body always press against the distribution plate without disengaging. At this time, the cylinder body will produce microscopic multi-degree-of-freedom overturning relative to the distribution plate, generating dynamic pressure effect, extrusion effect and solid micro-contact to balance this small amount of residual clamping force, thereby achieving dynamic force balance of the distribution pair.

[0052] Direct measurement of friction torque and leakage flow of the distribution pair is achieved by the following methods. Figure 4 As shown in the figure, when the cylinder body 18 rotates relative to the valve plate 5, the friction torque generated by the oil shear and solid contact at the valve plate interface directly acts on the surface of the valve plate 5. The valve plate 5 and the rear end cover 1 are axially compressed and circumferentially constrained. The friction torque is transmitted to the compression-torsion composite sensor 3 through the valve plate 5 and the rear end cover 1. Figure 5 As shown, the compression-torsion composite sensor 3 utilizes a double-flange structure, with the outer ring 3b fixed to the housing 4 and the inner ring 3a connected to the rear end cover 1. This allows for direct measurement of both axial force and friction torque. As mentioned above, the plunger cavity sealing plug eliminates leakage from the plunger and shoe assemblies. Therefore, the leakage flow directly measured within the housing using a gear flowmeter is the leakage flow of the distribution pair.

[0053] The in-situ monitoring of the cylinder body's multi-degree-of-freedom tilting characteristics and the oil film thickness field of the distribution pair is achieved in the following ways. Figure 6 As shown in the figure, the cylinder overturning posture and the oil film thickness field of the distribution pair are determined by measuring the oil film thickness at three non-collinear points on the bottom surface of the cylinder. Three eddy current displacement sensors S1, S2 and S3 are installed on the rear end cover 1, which are 120° apart. Figure 7 As shown, to protect the sensor from damage due to external forces during assembly and disassembly, and to prevent leakage caused by sensor wires protruding from the housing, the rear end cover 1 is provided with a first annular wiring groove 1a and a second annular sealing groove 1b. The three eddy current sensor wires are rationally arranged through the first annular wiring groove 1a and extend from the axial end of the rear end cover 1, effectively preventing damage to the sensor wires. The second annular sealing groove 1b is equipped with an O-ring to prevent oil leakage from the interior of the housing 4 to the outside, thereby ensuring measurement reliability and sealing. The oil film thickness h(r,θ) at any point can be determined by the following formula:

[0054] (7)

[0055] Where r is the radius of any point on the valve pair, θ is the angular displacement of any point on the valve pair, and h1, h2, and h3 are the oil film thicknesses measured by the three displacement sensors. The cylinder's overturning angle γ and overturning direction ζ can be calculated using the following formula:

[0056] (8)

[0057] (9)

[0058] The eddy current sensor 20 measures distance based on the principle of electromagnetic induction, so the metal materials around the sensor and other sensors may interfere with the measurement results. In order to avoid affecting the sensor's measurement sensitivity, a measuring disc 6 is installed on the outer edge of the cylinder 18 to ensure sufficient sensor detection area. The measured surface of the measuring disc 6 is more than twice the diameter of the probe, the radial distance of the metal materials around the sensor 20 is more than 1.5 times the diameter of the probe, and the distance between the two sensors is more than 6 times the diameter of the probe. The eddy current displacement sensor 20 has different ranges and sensitivities when detecting different materials. In particular, its linearity decreases significantly for non-ferrous materials. Therefore, the measuring disc 6 should preferably be made of ferrous materials. For non-ferrous materials, the sensor 20 needs to be calibrated before testing. The oil film thickness is a direct description of the lubrication characteristics of the distribution pair. If the minimum oil film thickness of the distribution pair is less than the surface roughness of the mating surface, the distribution pair will be in a mixed lubrication state or even boundary lubrication, and solid contact will occur between the cylinder 18 and the distribution disc 5, resulting in wear.

[0059] The embodiments described above are merely descriptions of preferred implementations of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should fall within the scope of protection determined by the claims of the present invention.

Claims

1. A simulated in-situ testing device for the dynamic lubrication characteristics of a distribution pair, characterized in that: The device includes a rotating component and a transmission component; The rotating component consists of a cylinder body, a distribution plate, a pseudo plunger shoe assembly, an eddy current sensor, a ball joint, a center spring, and a plunger cavity sealing plug; the pseudo plunger shoe assembly is embedded in the corresponding cylinder hole of the cylinder body, and the plunger cavity sealing plug is installed at the bottom of the cylinder hole with an interference fit; the center spring is pre-compressed and embedded in the cylinder body, pressing the ball joint toward the return plate on one side and the cylinder body toward the distribution plate on the other side. The back of the distribution plate is tightly fitted with the rear end cover, and radial displacement is constrained by the positioning pin; three eddy current displacement sensors are installed on the outer circle of the distribution plate at a 120° angle to each other. The pseudo plunger and slipper assembly comprises a plunger, a slipper, a return plate and a rotating support plate, which are connected as a whole by a set of screws; each pair of plungers and slippers are hinged together by a ball head and a ball socket, and the slipper is pressed against the surface of the rotating support plate with a zero inclination angle by the action of the high-pressure oil in the plunger chamber, so that the plunger does not need to reciprocate and extend in the cylinder bore; the return plate is fixed on the rotating support plate and clamps the outer circle of the slipper to limit the axial displacement of the slipper; the rotating support plate and the main shaft have an interference fit, and the angular contact ball bearing and the rotating support plate have a clearance fit, and bear both axial and radial loads at the same time; the pseudo plunger and slipper assembly completely eliminates the effects of friction and leakage caused by the plunger pair and the slipper pair through friction conversion, thereby realizing independent measurement of the friction torque and leakage flow of the distribution pair; The transmission component consists of a main shaft, an angular contact ball bearing, a needle roller bearing, and an oil seal. The main shaft runs through the entire rotating assembly and drives the cylinder body to rotate through a spline pair. The two ends are supported by needle roller bearings and angular contact ball bearings on the front and rear end covers respectively. The oil seal is installed between the main shaft and the front end cover to seal the oil leakage in the housing. Under the combined effect of the pressure difference between the inside and outside of the distribution pair sealing belt and the relative movement of the paired parts, the oil is brought into the gap of the distribution pair to form an oil film, isolating the paired parts and forming a stable oil film static pressure support to balance the external load force; at this time, the cylinder body undergoes microscopic multi-degree-of-freedom overturning, generating dynamic pressure effect, extrusion effect and solid micro-contact to balance the residual clamping force of the static pressure support, thereby achieving dynamic force balance of the distribution pair.

2. The device for testing the dynamic lubrication characteristics of a distribution pair in a simulated in-situ manner according to claim 1, characterized in that: The plunger cavity sealing plug is provided with an O-ring to form a radial seal with the cylinder hole. The high-pressure oil is sealed by the plunger cavity sealing plug. The high-pressure oil will neither leak from the plunger pair gap to the housing, nor leak from the slipper pair gap into the housing through the damping hole of the plunger slipper, thereby eliminating the leakage loss of the plunger pair and slipper pair from the source. The gear flowmeter is used to directly measure the leakage flow in the housing, which is the leakage flow of the distribution pair.

3. The device for testing the dynamic lubrication characteristics of a distribution pair in a simulated in-situ manner according to claim 1, characterized in that: The test device also includes a shell component, which consists of a shell, a front cover, a rear cover and a compression-torsion composite sensor, which are connected to each other by a bolt array; the compression-torsion composite sensor adopts a double flange structure, with the outer ring fixed to the shell and the inner ring connected to the rear cover, while realizing direct measurement of axial force and friction torque; the friction torque of the distribution pair interface directly acts on the surface of the distribution plate, and the distribution plate and the rear cover are axially compressed and circumferentially constrained, and the friction torque is transmitted to the compression-torsion composite sensor through the distribution plate and the rear cover.

4. The device for testing the dynamic lubrication characteristics of a distribution pair in a simulated in-situ manner according to claim 1, characterized in that: The high and low pressure oils introduced from the oil port of the rear end cover are diverted through the waist groove of the distribution plate and enter the plunger cavity from the waist groove of the cylinder body; the axial load generated by the high pressure oil acts on the bottom of the cylinder body, generating an axial clamping force to press the cylinder body towards the distribution plate.

5. The device for testing the dynamic lubrication characteristics of a distribution pair in a simulated in-situ manner according to claim 1, characterized in that: Three eddy current displacement sensors with an angle of 120° to each other are installed on the rear end cover. By measuring the oil film thickness at three non-collinear points on the bottom of the cylinder, the oil film thickness at any point and the overturning angle and overturning direction of the cylinder can be determined.

6. The device for testing the dynamic lubrication characteristics of a distribution pair in a simulated in-situ manner according to claim 1, characterized in that: The ratio of the static pressure support force on the cylinder body generated by the oil film pressure of the distribution window and the sealing belt to the axial compression force generated by the high-pressure oil is defined as the balance coefficient. The axial compression force under this balance coefficient makes the cylinder body always press against the distribution plate without falling off.

7. The device for testing the dynamic lubrication characteristics of a distribution pair in a simulated in-situ manner according to claim 5, characterized in that: The rear end cover is respectively provided with a first annular wiring groove and a second annular sealing groove. The three eddy current sensor wires are rationally arranged through the first annular wiring groove and extend from the shaft end of the rear end cover to avoid damage to the sensor wires. The second annular sealing groove 1b is installed with an O-ring to prevent oil from leaking from the inside of the housing to the outside, thereby ensuring measurement reliability and sealing.

8. The device for testing the dynamic lubrication characteristics of a distribution pair in a simulated in-situ manner according to claim 5, characterized in that: A measuring disc is installed on the outer edge of the cylinder body, and the bottom is flush with the mating surface of the cylinder body. The eddy current sensor probe is parallel to the plane of the measuring disc, and an appropriate gap is left. The measured surface of the measuring disc is more than twice the diameter of the probe. The radial distance of the metal material around the sensor is more than 1.5 times the diameter of the probe, and the distance between the two sensors is more than 6 times the diameter of the probe.

9. A virtual in-situ testing method for the dynamic lubrication characteristics of a distribution pair based on the virtual in-situ testing device according to any one of claims 1 to 8, characterized in that: The method comprises the following steps: (1) The main shaft cooperates with the driving cylinder to drive the pseudo plunger sliding shoe assembly to rotate, so that the distribution pair is in dynamic force balance; (2) The axial force and friction torque are measured based on the compression-torsion composite sensor, and the leakage flow in the shell is measured by the gear flowmeter, which is the leakage flow of the distribution pair; (3) The overturning posture of the cylinder and the oil film thickness field of the distribution pair are determined by measuring the oil film thickness at three non-collinear points on the bottom surface of the cylinder.

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