Quasi-real in-situ testing device and method for dynamic lubrication characteristic of flow distribution pair

Abstract

The invention discloses a quasi-real in-situ testing device and a quasi-real in-situ testing method for dynamic lubrication characteristics of a flow distribution pair, designs a set of pseudo plunger piston shoe assembly, removes the influence of friction and leakage caused by a plunger pair and a piston shoe pair through friction conversion, and realizes independent measurement of friction torque and leakage flow of the flow distribution pair. Meanwhile, the design structure of the flow distribution pair based on the residual pressing force method is reserved, the actual dynamic bearing lubrication state of the flow distribution pair can be truly simulated, and in-situ measurement of the motion characteristics of multi-degree-of-freedom overturning of the cylinder body is achieved. Important test basis is provided for analyzing the distributed dynamic lubrication characteristics of the flow distribution pair, only an existing plunger pump needs to be transformed, original core rotating assembly structures such as a cylinder body, a plunger and a sliding shoe are reserved, machining is easy, and cost is low.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydraulic pumps, and particularly relates to a quasi-real in-situ test device and method for the dynamic lubrication characteristics of a flow distribution pair. Background Technique

[0002] An axial piston pump is a hydraulic pump that changes the volume in the piston cavity by the reciprocating motion of the piston in the cylinder bore. Compared with other positive displacement pumps, it has advantages such as high power density, high working efficiency, and long service life, and is widely used in the fields of construction machinery, aerospace, mobile robots, etc. The flow distribution pair formed by the rotating cylinder block and the valve plate is a very critical pair of friction pairs in the piston pump. Its frictional loss and leakage flow are the main sources of the mechanical loss and volumetric loss of the piston pump. Therefore, by building a test device to study the dynamic load-bearing lubrication mechanism of the flow distribution pair is crucial for guiding the optimized design of the piston pump.

[0003] The design of the flow distribution pair widely adopts the "residual pressing force" design method. The pressing force generated by the high-pressure oil in the piston cavity presses the cylinder block against the valve plate. At the same time, the high-pressure oil forms an extremely thin hydraulic oil film in the gap of the flow distribution pair, and the generated hydraulic support force attempts to push the cylinder block away. Most of the pressing force is balanced by the oil film, but a small part of the residual pressing force remains to press the cylinder block on the valve plate, so that the cylinder block can always press against the valve plate without disengaging. This unique "residual pressing force" design method enables the flow distribution pair to have multiple functions of load-bearing, sealing, and lubrication.

[0004] Among the currently put-into-use and publicly disclosed or authorized patents, the test methods for the oil film of the flow distribution pair are mainly divided into two types. One is based on the transformation of a real pump (such as an on-line test device for the oil film characteristics of a hydraulic pump flow distribution pair based on the transformation of the end cover, ZL115076089A), and the other is carried out on a model pump (such as a comprehensive test device for the flow distribution pair of a piston pump, ZL110836178A). The test device based on the transformation of a real pump is limited by the narrow installation space of the pump, and only a limited type of sensors such as eddy current sensors and thermocouples can be installed on the rear end cover of the valve plate. Moreover, in the real pump, the flow distribution pair is affected by the piston pair and the slipper pair, and the frictional torque and leakage flow of the flow distribution pair cannot be measured independently. The test device based on the simulation pump approximates the flow distribution pair to a simple ring-disk friction pair. However, in actual operation, the piston pump inevitably receives impact loads, and also includes working states of rapid start-stop and frequent commutation. The bottom surface of the cylinder block cannot maintain an ideal parallel posture with the surface of the valve plate, but will undergo micro-movements of multi-degree-of-freedom overturning, and the oil film is always in the process of dynamic adjustment. Therefore, although this method is simple, it does not follow the residual pressing force design method and cannot truly simulate the dynamic load-bearing characteristics of the oil film of the flow distribution pair. Summary of the Invention

[0005] The object of the present invention is to provide a virtual in-situ test device and method for the dynamic lubrication characteristics of a flow distribution pair in view of the deficiencies of the prior art, so as to provide an important experimental basis for analyzing the distributed dynamic lubrication characteristics and failure mechanism of the flow distribution pair.

[0006] The virtual in-situ test device for the dynamic lubrication characteristics of a flow distribution pair provided by the present invention is realized through the following technical solutions: A virtual in-situ test device for the dynamic lubrication characteristics of a flow distribution pair, the device includes a rotating component and a transmission component;

[0007] The rotating component is composed of a cylinder block, a flow distribution plate, a pseudo-plunger shoe assembly, an eddy current sensor, a ball joint, a central spring and a plunger cavity seal plug; the pseudo-plunger shoe assembly is embedded in the corresponding cylinder hole of the cylinder block, and the plunger cavity seal plug is installed in the bottom of the cylinder hole with interference fit; the central spring is pre-compressed and then embedded in the cylinder block, pressing the ball joint against the return disk on one side and pressing the cylinder block against the flow distribution plate on the other side. The back surface of the flow distribution plate is closely attached to the rear end cover, and the radial displacement is restricted by a positioning pin; 3 eddy current displacement sensors are installed at the outer circumference of the flow distribution plate at an angle of 120° to each other.

[0008] The pseudo-plunger shoe assembly includes a plunger, a shoe, a return disk and a rotating support disk, which are connected into a whole by a set of screws; each pair of plungers and shoes are hinged together by a ball head and a ball socket. The shoe is pressed against the surface of the rotating support disk with a 0° inclination angle under the action of the high-pressure oil in the plunger cavity. The return disk is fixed on the rotating support disk and restricts the axial displacement of the shoe by jamming the outer circumference of the shoe.

[0009] The transmission component is composed of a main shaft, angular contact ball bearings, needle bearings and oil seals; the main shaft passes through the entire rotating assembly and drives the cylinder block to rotate through a spline pair. The two ends are respectively supported on the front and rear end covers by needle bearings and angular contact ball bearings. The oil seal is installed in the main shaft and the front end cover with interference fit to seal the leaked oil in the housing.

[0010] Furthermore, the plunger cavity seal 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 seal plug. The high-pressure oil will neither leak from the plunger pair gap to the housing nor leak from the shoe pair gap to the housing through the damping hole of the plunger shoe, eliminating the leakage loss of the plunger pair and the shoe pair from the source. The leakage flow in the housing is directly measured by a gear flowmeter, which is the leakage flow of the flow distribution pair.

[0011] Furthermore, the test device further includes a housing component, which consists of a housing, a front end cover, a rear end cover, and a compression-torsion composite sensor. They are connected to each other through a bolt array pairwise. The compression-torsion composite sensor adopts a double flange structure. The outer ring is fixed to the housing, and the inner ring is connected to the rear end cover, realizing the direct measurement of axial force and frictional torque at the same time. The frictional torque at the interface of the flow distribution pair directly acts on the surface of the flow distribution plate. The flow distribution plate is axially pressed and circumferentially constrained between the rear end cover. The frictional torque is transmitted to the compression-torsion composite sensor through the flow distribution plate and the rear end cover.

[0012] Furthermore, the high and low pressure hydraulic fluids introduced through the oil ports of the rear end cover are shunted through the waist-shaped grooves of the flow distribution plate and enter the plunger cavity through the waist-shaped grooves of the cylinder block. The axial load generated by the high-pressure hydraulic fluid acts on the bottom of the cylinder block, generating an axial pressing force to press the cylinder block against the flow distribution plate.

[0013] Furthermore, under the combined action of the pressure difference inside and outside the sealing band of the flow distribution pair and the relative movement of the mating parts, the hydraulic fluid is brought into the gap of the flow distribution pair to form an oil film, separating the mating parts and forming a stable oil film hydrostatic support to balance the external load force. At this time, the cylinder block undergoes microscopic multi-degree-of-freedom overturning, generating hydrodynamic effect, extrusion effect, and solid micro-contact to balance the remaining pressing force of the hydrostatic support, thereby realizing the dynamic force balance of the flow distribution pair.

[0014] Furthermore, three eddy current displacement sensors with an included 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 block, the oil film thickness at any point, as well as the overturning angle and overturning orientation of the cylinder block, can be determined.

[0015] Furthermore, the ratio of the hydrostatic support force on the cylinder block generated by the oil film pressure of the flow distribution window and the sealing band to the axial pressing force generated by the high-pressure hydraulic fluid is defined as the balance coefficient. The axial pressing force under this balance coefficient keeps the cylinder block always pressed against the flow distribution plate without disengaging.

[0016] Furthermore, the rear end cover is respectively provided with a first annular wire groove and a second annular sealing groove. The wires of the three eddy current sensors are reasonably arranged through the first annular wire groove and extend out 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 seal to prevent the leakage of hydraulic fluid from the inside of the housing to the outside, ensuring the reliability and tightness of the measurement.

[0017] Furthermore, a measurement disk is installed on the outer edge of the cylinder block, and its bottom is flush with the mating surface of the cylinder block. The probe of the eddy current sensor is parallel to the plane of the measurement disk, and an appropriate gap is left. The measured surface of the measurement disk is more than 2 times the diameter of the probe. The distance of the metal material around the sensor in the radial direction 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 for a virtual in-situ testing device based on the dynamic lubrication characteristics of a flow distribution pair, and the method includes the following steps:

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

[0020] (2) Based on the compression-torsion composite sensor, the axial force and the frictional torque are measured, and the gear flowmeter is used to measure the leakage flow rate in the housing, which is the leakage flow rate of the flow distribution pair;

[0021] (3) By measuring the oil film thickness at three non-collinear points on the bottom surface of the cylinder block, the tilting posture of the cylinder block and the oil film thickness field of the flow distribution pair are determined.

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

[0023] 1. Compared with the previous testing devices based on real pumps, the present invention designs a set of pseudo-plunger slipper assemblies. Through friction conversion, the influences of friction and leakage brought by the plunger pair and the slipper pair are completely eliminated, and the direct measurement of the frictional torque and leakage flow rate of the single flow distribution pair is realized.

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

[0025] 3. The present invention only needs to be modified on the existing plunger pump, retains the core rotating component structures such as the original cylinder block, plunger, and slipper, and has simple processing and low cost. Description of the Drawings

[0026] Figure 1 is the overall axonometric view of the present invention;

[0027] Figure 2 is the overall sectional view of the present invention;

[0028] Figure 3 is the schematic diagram of the core rotating components;

[0029] Figure 4 is the core part for measuring the frictional torque of the flow distribution pair.

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

[0031] Figure 6 is the core part for measuring the dynamic oil film clearance of the flow distribution pair;

[0032] Figure 7Schematic 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. Inner ring of the compression-torsion composite sensor, 3b. Outer ring of the compression-torsion composite sensor, 4. Housing, 5. Distribution plate, 5a. Sealing strip of the distribution plate, 5b. Waist-shaped groove of the distribution plate, 6. Measuring plate, 7. Plunger chamber seal plug, 8. Plunger, 9. Slipper, 10. Angular contact ball bearing, 11. Front end cover, 12. Oil seal, 13. Main shaft, 14. Rotating support plate, 15. Return spring plate, 16. Ball hinge, 17. Central spring, 18. Cylinder block, 19. Needle bearing, 20. Eddy current sensor. Detailed implementation mode

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

[0036] As Figure 1 and Figure 2 shown, in an embodiment, the present invention provides a virtual in-situ test device and test method for the dynamic lubrication characteristics of a distribution pair. Its main working principle is: a set of pseudo-plunger slipper assemblies are designed, and through friction conversion, the influences of friction and leakage brought by the plunger pair and the slipper pair are completely eliminated, realizing the independent measurement of the friction torque and leakage flow rate of the distribution pair. At the same time, the remaining pressing force design structure of the distribution pair is retained, simulating the real dynamic load-bearing lubrication characteristics of the distribution pair, and realizing the in-situ monitoring of the multi-degree-of-freedom overturning characteristics of the cylinder block. The specific structure is as follows:

[0037] The housing components of the test device are composed of the following parts. The housing 4, the front end cover 11 and the outer ring 3b of the compression-torsion composite sensor are connected to each other through a bolt array pairwise, and an O-ring is arranged between the mating surfaces for sealing. The rear end cover 1 extends out from the central circular hole of the inner ring 3a of the compression-torsion composite sensor and is connected together by bolts. The O-ring is installed in the sealing groove 1b on the back of the rear end cover 1 to seal the wiring groove 1a. High and low pressure flow channels 1c are opened inside the rear end cover 1, and the pressure sensor 2 is installed on the side of the rear end cover 1 through threads to measure the pressure of the high and low pressure oil ports 1c.

[0038] The rotating components of the test device are composed of the following parts. As Figure 3As shown in the figure, the cylinder bores of the cylinder block 18 circumferentially and equidistantly contain an odd number of plungers 8 with clearances. The plunger chamber sealing plug 7 is press-fitted and embedded at the bottom of the cylinder bore to seal the cylinder bore and the plunger 8 assembly. Each pair of plungers 8 and slipper shoes 9 are hinged together by a ball head and a ball socket. The slipper shoes 9 are pressed against the surface of the rotating support disk 14 by the high-pressure oil in the plunger chamber. The return disk 15 is fixed to the rotating support disk 14 by screws and holds the outer circle of the slipper shoes 9 to limit the axial displacement of the slipper shoes 9. The plungers 8, slipper shoes 9, return disk 15 and rotating support disk 14 are mutually constrained to jointly form a set of pseudo-plunger slipper shoe assembly. The rotating support disk 14 is press-fitted with the main shaft 13, and the angular contact bearing 10 has a clearance fit with the rotating support disk 14 and bears both axial and radial loads at the same time. The central spring 17 is embedded in the middle cavity of the cylinder block 18. After being pre-compressed, the central spring applies forces to both sides. On the one hand, it presses the ball hinge 16 towards the return disk 15, and on the other hand, it tightly presses the cylinder block 18 against the upper surface of the valve plate 5 through a snap ring. The back surface of the pressed valve plate 5 is closely attached to the rear end cover 1, and the radial displacement is restricted by a positioning pin. Three eddy current displacement sensors 20 are installed at the outer circle of the valve plate. The eddy current displacement sensors 20 are mutually at an angle of 120° and are fastened in the threaded holes of the rear end cover 1. The transmission of the sensors is first led out through the wiring groove 1a on the back surface of the end cover 1. The measuring disk 6 is installed at the outer edge of the cylinder block 18 through fastening screws, and the bottom surface of the measuring disk 6 is flush with the mating surface of the cylinder block. The eddy current sensor probe is parallel to the plane of the measuring disk and has an appropriate clearance.

[0039] The transmission components of the test device are composed of the following parts. The main shaft 13 runs through the rotating components of the whole device. The external spline of the main shaft 13 has a clearance fit with the internal spline of the cylinder block 18 to drive the cylinder block 18 to rotate. The rear end is supported on the rear end cover 1 by a needle roller bearing 19, and the front end is supported on the front end cover 10 by an angular contact ball bearing 10. The oil seal 12 is press-fitted between the main shaft 13 and the front end cover 11 to seal the leaked oil in the housing.

[0040] The friction and leakage caused by the plunger pair and the slipper shoe pair are eliminated in the following ways. As Figure 3 shown, during operation, the plungers 8, slipper shoes 9, return disk 15 and rotating support disk 14 are connected into a whole by a set of screws to jointly form a set of pseudo-plunger slipper shoe assembly. The main shaft 13 drives the cylinder block 18 to drive the pseudo-plunger slipper shoe assembly to rotate through spline fit. The rotating support disk 14 is designed with a 0 inclination angle. The plungers 8 do not need to reciprocate and extend in the cylinder bore, and the slipper shoes 9 do not need to slide relative to the rotating support disk 14, eliminating the frictional losses caused by the plungers 8 and slipper shoes 9 assemblies in terms of the motion form. In addition, the plunger chamber sealing plug 7 is provided with an O-ring to form a radial seal with the cylinder bore. The high-pressure oil is sealed by the plunger chamber sealing plug 7. The high-pressure oil will neither leak from the plunger pair clearance to the housing nor leak from the slipper shoe pair clearance to the housing through the damping holes of the plungers 8 and slipper shoes 9, eliminating the leakage losses of the plunger pair and the slipper shoe pair from the source.

[0041] The design of retaining the remaining clamping force of the flow distribution pair is achieved in the following way. Conduct a force analysis on the structure of the flow distribution pair. Introduce high and low pressure hydraulic oil through the oil ports of the rear end cover 1c, divide the flow through the waist-shaped grooves 5b on the flow distribution plate, and enter the plunger cavity from the waist-shaped grooves on the cylinder block. The axial load generated by the high-pressure hydraulic oil is transmitted to the angular contact ball bearing through the sealing plug 7 of the plunger cavity, the plunger 8, the slipper 9, and the rotating support plate 14 on the one hand, and acts on the bottom of the cylinder block 18 on the other hand, generating an axial clamping force to press the cylinder block 18 against the flow distribution plate 5. The axial clamping force F clamp and the overturning moment M caused by the imbalance between the high and low pressure sides tilt are shown in the following formula:

[0042] (1)

[0043] (2)

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

[0045] (3)

[0046] In the formula, p H is the oil pressure in the high-pressure oil circuit, p L is the oil pressure in the low-pressure oil circuit. Under the combined action of the pressure difference inside and outside the sealing belt of the flow distribution pair and the relative movement of the mating pair of the cylinder block 18 and the flow distribution plate 5, oil with a certain viscosity is brought into the gap of the flow distribution pair to form an oil film, separating the mating pair to form a stable static and dynamic pressure support of the oil film to balance the external load force. At the same time, the pressure reduction and throttling effect of the gap oil film prevent the oil in the plunger cavity from leaking to the housing. The static pressure support force F hydrostatic and the anti-overturning moment M hydrostatic are shown in the following formula:

[0047] (4)

[0048] (5)

[0049] In the formula, R1 and R2 are the inner and outer radii of the inner seal respectively, R3 and R4 are the inner and outer radii of the outer seal respectively, φ His the pressure zone wrap angle. The hydrostatic bearing formed by the clearance flow between the valve plate 5 and the cylinder block 18 can offset most of the axial pressing force. The ratio of the hydrostatic support force to the axial pressing force is defined as the balance coefficient B b , denoted as:

[0050] (6)

[0051] In the remaining pressing force design method, the balance coefficient is usually taken as 0.95 - 1, that is, about 5% of the pressing force makes the cylinder block always press against the valve plate without disengaging. At this time, the cylinder block will have a microscopic multi-degree-of-freedom overturning relative to the valve plate, generating a hydrodynamic effect, an extrusion effect, and solid micro-contact to balance this small part of the remaining pressing force, so as to achieve the dynamic force balance of the flow distribution pair.

[0052] The direct measurement of the friction torque and leakage flow rate of the flow distribution pair is achieved through the following methods. As Figure 4 shown, when the cylinder block 18 rotates relative to the valve plate 5, the friction torque generated by the oil shear and solid contact at the interface of the flow distribution pair directly acts on the surface of the valve plate 5. The valve plate 5 and the rear end cover 1 are axially pressed and circumferentially constrained, and the friction torque is transmitted to the pressure-torsion composite sensor 3 through the valve plate 5 and the rear end cover 1. As Figure 5 shown, the pressure-torsion composite sensor 3 adopts a double-flange structure. The outer ring 3b is fixed to the housing 4, and the inner ring 3a is connected to the rear end cover 1, which can directly measure the axial force and friction torque at the same time. As mentioned above, the leakage of the plunger pair and the swash plate pair has been eliminated through the plunger cavity sealing plug. Therefore, the leakage flow rate in the housing is directly measured by a gear flowmeter, which is the leakage flow rate of the flow distribution pair.

[0053] The in-situ monitoring of the multi-degree-of-freedom overturning characteristics of the cylinder block and the oil film thickness field of the flow distribution pair is achieved through the following methods. As Figure 6 shown, the overturning posture of the cylinder block and the oil film thickness field of the flow distribution pair are determined by measuring the oil film thickness at three non-collinear points on the bottom surface of the cylinder block. Three eddy current displacement sensors S1, S2, and S3 with an included angle of 120° to each other are installed on the rear end cover 1. As Figure 7 shown, in order to avoid damage to the sensors due to external forces during disassembly and assembly, and at the same time prevent leakage problems that may be caused by the sensor wires protruding from the inside of the housing, the rear end cover 1 is respectively provided with a first annular wire routing groove 1a and a second annular sealing groove 1b. The three eddy current sensor wires are reasonably arranged through the first annular wire routing groove 1a and extend from the shaft end of the rear end cover 1, effectively avoiding 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 4 to the outside, thus ensuring the reliability and tightness of the measurement. 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 flow distribution pair, θ is the angular displacement of any point on the flow distribution pair, and h1, h2, and h3 are the oil film thicknesses measured by three displacement sensors respectively. The tilting angle γ and tilting orientation ζ of the cylinder block can be calculated by the following formula:

[0056] (8)

[0057] (9)

[0058] The eddy current sensor 20 measures the distance based on the principle of electromagnetic induction. Therefore, the metal materials and other sensors around the sensor may interfere with the measurement results. To avoid affecting the measurement sensitivity of the sensor, a measurement disk 6 is installed on the outer edge of the cylinder block 18 to provide a sufficient detection area for the sensor. The measured surface of the measurement disk 6 is more than twice the diameter of the probe. The distance of the metal material around the sensor 20 in the radial direction is more than 1.5 times the diameter of the probe, and the distance between 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. Especially for non-ferrous materials, its linearity decreases significantly. Therefore, the measurement disk 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 flow distribution pair. If the minimum oil film thickness of the flow distribution pair is less than the surface roughness of the mating surface, the flow distribution pair will be in a mixed lubrication state or even a boundary lubrication state, and solid contact will occur between the cylinder block 18 and the flow distribution disk 5, resulting in wear.

[0059] The embodiments described above are only for describing the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A quasi-real in-situ test device for the dynamic lubrication characteristics of a flow distribution pair, characterized in that The device includes a rotating component and a transmission component; The rotating component consists of a cylinder block, a valve plate, a pseudo-plunger slider shoe assembly, an eddy current sensor, a ball hinge, a central spring and a plunger cavity seal plug; the pseudo-plunger slider shoe assembly is embedded in the corresponding cylinder bore of the cylinder block, and the plunger cavity seal plug is press-fitted at the bottom of the cylinder bore; the central spring is pre-compressed and then embedded in the cylinder block, pressing the ball hinge towards the return disk on one side and pressing the cylinder block towards the valve plate on the other side. The back of the valve plate is closely attached to the rear end cover, and the radial displacement is restricted by a positioning pin; three eddy current displacement sensors are installed at the outer circumference of the valve plate at an angle of 120° to each other. The pseudo-plunger slider shoe assembly includes a plunger, a slider shoe, a return disk and a rotating support disk, which are connected into a whole by a set of screws; each pair of plunger and slider shoe is hinged together by a ball head and a ball socket. The slider shoe is pressed on the surface of the rotating support disk with a 0° inclination angle under the action of the high-pressure oil in the plunger cavity. The return disk is fixed on the rotating support disk and holds the outer circumference of the slider shoe to restrict the axial displacement of the slider shoe. The transmission component consists of a main shaft, angular contact ball bearings, needle bearings and oil seals; the main shaft passes through the entire rotating assembly and drives the cylinder block to rotate through a spline pair. The two ends are respectively supported on the front and rear end covers by needle bearings and angular contact ball bearings. The oil seal is press-fitted between the main shaft and the front end cover to seal the leaked oil in the housing.

2. The quasi-real in-situ test device for the dynamic lubrication characteristics of a flow distribution pair according to claim 1, characterized in that, The plunger cavity seal plug is provided with an O-ring to form a radial seal with the cylinder bore. The high-pressure oil is sealed by the plunger cavity seal plug. The high-pressure oil will neither leak from the plunger pair gap to the housing nor leak from the slider shoe pair gap to the housing through the damping hole of the plunger slider shoe, eliminating the leakage loss of the plunger pair and the slider shoe pair from the source. The leakage flow rate in the housing is directly measured by a gear flowmeter, which is the leakage flow rate of the valve plate pair.

3. The quasi-real in-situ testing device for the dynamic lubrication characteristics of a flow distribution pair according to claim 1, characterized in that, The test device also includes a housing component, which consists of a housing, a front end cover, a rear end cover and a compression-torsion composite sensor, and they 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 housing and the inner ring connected to the rear end cover, directly measuring the axial force and the frictional torque at the same time; the frictional torque at the valve plate pair interface directly acts on the surface of the valve plate, and the valve plate and the rear end cover are axially pressed and circumferentially constrained. The frictional torque is transmitted to the compression-torsion composite sensor through the valve plate and the rear end cover.

4. The quasi-real in-situ test device for the dynamic lubrication characteristics of a flow distribution pair according to claim 1, characterized in that, The high and low pressure oil introduced from the oil port of the rear end cover is shunted through the waist-shaped groove of the valve plate and enters the plunger cavity from the waist-shaped groove of the cylinder block; the axial load generated by the high-pressure oil acts on the bottom of the cylinder block, generating an axial pressing force to press the cylinder block towards the valve plate.

5. The quasi-real in-situ test device for the dynamic lubrication characteristics of a flow distribution pair according to claim 1, characterized in that Under the combined action of the pressure difference inside and outside the seal belt of the valve plate pair and the relative movement of the mating parts, the oil is brought into the gap of the valve plate pair to form an oil film, separating the mating parts and forming a stable oil film hydrostatic support to balance the external load force; at this time, the cylinder block undergoes microscopic multi-degree-of-freedom overturning, generating a hydrodynamic effect, an extrusion effect and solid micro-contact to balance the remaining pressing force of the hydrostatic support, thereby achieving the dynamic force balance of the valve plate pair.

6. The quasi-real in-situ test device for the dynamic lubrication characteristics of a flow distribution pair according to claim 1, characterized in that, Three eddy current displacement sensors are installed on the rear end cover at an angle of 120° to each other. By measuring the oil film thickness at three non-collinear points on the bottom surface of the cylinder block, the oil film thickness at any point, the overturning angle and the overturning orientation of the cylinder block can be determined.

7. The quasi-real in-situ test device for the dynamic lubrication characteristics of a flow distribution pair according to claim 5, characterized in that Define the ratio of the static pressure support force on the cylinder block generated by the oil film pressure of the flow distribution window and the sealing belt to the axial pressing force generated by the high-pressure oil as the balance coefficient. The axial pressing force under this balance coefficient keeps the cylinder block pressing against the valve plate all the time without detachment.

8. The quasi-real in-situ test device for the dynamic lubrication characteristics of a flow distribution pair according to claim 6, characterized in that, The rear end cover is respectively provided with a first annular wire groove and a second annular sealing groove. The three eddy current sensor wires are reasonably arranged through the first annular wire groove and extend out from the shaft end of the rear end cover to avoid damage to the sensor wires. An O-ring seal is installed in the second annular sealing groove 1b to prevent the oil from leaking from the inside of the housing to the outside, ensuring the reliability and tightness of the measurement.

9. The quasi-real in-situ test device for the dynamic lubrication characteristics of a flow distribution pair according to claim 6, characterized in that, A measuring disk is installed on the outer edge of the cylinder block, and its bottom is flush with the mating surface of the cylinder block. 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 distance of the metal material around the sensor in the radial direction 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.

10. A virtual in-situ testing method for a virtual in-situ testing device of the dynamic lubrication characteristics of a flow distribution pair according to any one of claims 1-9, characterized in that, This method includes the following steps: (1) The main shaft cooperates with the drive to drive the cylinder block to drive the pseudo-plunger shoe assembly to rotate, so that the flow distribution pair is in dynamic force balance. (2) Measure the axial force and frictional torque based on the pressure-torsion composite sensor, and use a gear flowmeter to measure the leakage flow rate in the housing, which is the leakage flow rate of the flow distribution pair. (3) Determine the tilting attitude of the cylinder block and the oil film thickness field of the flow distribution pair by measuring the oil film thickness at three non-collinear points on the bottom surface of the cylinder block.

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