Cycloid pump rotor end face gap design method

Abstract

The invention belongs to the technical field of aviation equipment calculation and analysis, and discloses a cycloid pump rotor end face gap design method which comprises the steps of calculating structural deformation of a pump under mechanical and thermal loads, obtaining a rotor anti-abrasion minimum end face gap, analyzing end face gap flow loss, evaluating pump flow performance and obtaining a rotor maximum end face gap. Determining the rotor end face design tolerance. According to the method, the minimum value of the rotor end face gap is obtained through a solidification structure simulation modeling equivalent method and a post-processing method, the maximum value of the rotor end face gap is obtained through calculation by combining design indexes and performance numerical values, and then the optimal tolerance range of the end face gap is determined. According to the method, the rotor end face abrasion resistance and the end face gap flow loss of the cycloid pump are evaluated at the same time, the contradictory balance of the two parties is found, the pump is converted from empirical drive design to forward analysis design on key size control, and the reliability of a product in a service state is improved.

Description

Technical Field

[0001] This invention belongs to the field of aerospace equipment calculation and analysis technology, and relates to an analysis method for cycloidal pumps, specifically a method for designing the rotor end face clearance of a cycloidal pump. Background Technology

[0002] In the development of aero-cycloidal pumps, the design tolerances for the rotor fit are crucial, as these tolerances determine the leakage clearance, which includes the rotor end face clearance and radial clearance. According to literature, end face clearance leakage accounts for 70%–80% of the total leakage in cycloidal pumps; therefore, it is the most important of all leakage clearances and directly determines the volumetric efficiency of the cycloidal pump. Reducing the end face clearance can improve volumetric efficiency, but excessively small clearances can easily lead to rotor end face wear or jamming.

[0003] Currently, the range of rotor end-face clearance values ​​is usually set based on historical experience. However, with the upper lubrication system placing more demanding operating conditions on cycloidal pumps, such as wide temperature ranges and high pressures, the empirically determined range of end-face clearance design values ​​is no longer applicable to these new requirements. In addition to empirical design, in recent years, many researchers have used CFD technology to consider the range of end-face clearance values ​​only from a performance perspective. However, CFD calculations are complex and inefficient, and they do not consider the influence of structural stress and deformation on the end-face clearance. Therefore, there is a lack of research on assessing whether the rotor is experiencing wear or jamming. Summary of the Invention

[0004] To address the aforementioned issues, this invention proposes a method for designing the rotor end face clearance of a cycloidal pump. This method simultaneously evaluates the wear resistance of the rotor end face and the flow loss due to the end face clearance, finding a balance between the two conflicting aspects. Based on this balance, the design tolerance of the rotor end face is determined, enabling a shift from experience-driven design to forward analysis design in critical dimension control of the pump, thereby improving the reliability of the product under service conditions.

[0005] The technical solution of the present invention is as follows: A method for designing the rotor end face clearance of a cycloidal pump involves taking an initial three-dimensional model of the cycloidal pump designed using historical experience as input, and then performing the following steps: S1, calculate the structural deformation of the pump under mechanical and thermal loads; S2, to obtain the minimum wear-resistant end face clearance of the rotor; S3, analyze the flow loss through the end face gap; S4, evaluate pump flow performance; if the flow performance does not meet the requirements of the upper system, repeat S1~S4 until it does; S5, to obtain the maximum end face clearance of the rotor; S6, determine the rotor end face design tolerance.

[0006] Furthermore, S1 specifically includes the following steps: S11, simplified initial 3D model of cycloidal pump; S12, take the maximum value of the radial dimension tolerance of the housing, pump core, shaft, bearing and locating pin, and correct the cycloidal pump three-dimensional model; S13, Imprint the rotor rotation sweep surface on both sides of each partition, and create a set of unit surfaces; S14, establish a binding connection between the bearing and the partition. If the shaft is limited by a retaining ring, establish a multi-point coupling connection between the limiting surfaces of the shaft and the partition, and establish a surface-to-surface contact relationship between the remaining surfaces and assign contact properties. S15, create two load steps, the rotation load step type is thermo-coupling analysis, then first apply the disc spring force as a uniform pressure to the disc spring seat, and then apply the design pressure and temperature of the functional cavity to the inlet and outlet positions of the partitions on both sides of each functional cavity respectively, and constrain according to the performance test installation state. S16 sets the large deformation as a damping factor to increase the convergence of the simulation analysis, submits the implicit solver for calculation, and outputs the stress field, strain field and displacement field of the cycloidal pump.

[0007] Furthermore, in S11, the shell, diaphragm, eccentric sleeve, diaphragm positioning pin and pump core limiting component are retained in the initial three-dimensional model of the cycloidal pump, while other components, including the inner rotor, are deleted, thus completing the simplification of the initial three-dimensional model of the cycloidal pump.

[0008] Furthermore, in S14, the contact normal adopts the "Hard" Contact algorithm, and the contact tangential adopts the Penalty penalty function method and sets the friction coefficient to ensure rigid body operation and complete the definition of the cycloidal pump connection relationship.

[0009] Furthermore, S2 specifically refers to: S21. Compare the relationship between the equivalent stress of the component and the yield strength of the material. If the equivalent stress of the component is greater than the yield strength, the plasticity curve data needs to be added to the material constitutive parameters for simulation again to extract the structural deformation. Otherwise, the structural deformation is extracted directly. S22, extract the axial deformation of a pair of inner and outer rotors on the unit surface to obtain the minimum end face clearance required for rotor wear resistance; S23, take the maximum value among the minimum wear-resistant end face clearances of all rotors of the cycloidal pump as the minimum rotor end face clearance in the overall pump design.

[0010] Furthermore, S3 specifically refers to: S31. Use CAD software to scale the inner rotor and adjust the rotation center to the center of the outer rotor to complete the correction of the three-dimensional model; simplify the three-dimensional model, remove the chamfer of the oil distribution plate area, and extract the fluid domain of the oil distribution plate.

[0011] S32, import the CAD 3D model of the oil distribution plate fluid domain and the inner and outer rotors, identify the inner and outer gear contours, oil distribution inlet and outlet areas and volumes of the cycloidal pump, and convert the CAD 3D model into a 1D model. S33, calculate the leakage of the end face gap based on the "slit flow between perforated disks" in fluid mechanics; S34. Select motor components from the data machinery library, fixed signal components and moving average components from the signal library, and oil tank components, oil property components and flow meter components from the data hydraulic library to establish a complete one-dimensional simulation model of the cycloidal pump system; set the physical property parameters and boundary conditions of each component for simulation calculation.

[0012] Furthermore, in S33, a hydraulic vector hole element is used to model the end face clearance at both ends of the cycloidal pump; simultaneously, a hydraulic vector 3 interface element is used to transmit the pressure of each chamber of the cycloidal pump to the hydraulic vector hole element for leakage calculation; the leakage from the high-pressure chamber of the cycloidal pump to the bearing chamber is:

[0013] in, It is the end face clearance of the inner rotor; It is the pressure difference between the high-pressure chamber and the bearing chamber of the cycloidal pump; It is the dynamic viscosity of the oil; It is the radius of the rotor tooth root circle; It is the radius of the pivot; The leakage from the high-pressure chamber of the cycloidal pump to the outer circumference of the outer rotor is:

[0014] in, It is the radius of the outer circle of the outer rotor; It is the radius of the root circle of the outer rotor teeth.

[0015] Furthermore, S4 specifically refers to: Starting with the minimum end-face clearance obtained in S2, gradually increase the end-face clearance and plot the performance curves for different clearances. If the flow rate at the starting point (minimum clearance) does not meet the design flow rate requirements, it is necessary to return to modify the design scheme and repeat S1~S4.

[0016] Furthermore, S5 specifically refers to: On the performance curve, find the end face gap value corresponding to the design requirement flow rate, and use it as the maximum end face gap value.

[0017] Furthermore, S6 specifically refers to: The minimum end face clearance obtained by combining S2 and the maximum end face clearance obtained by S5 form the rotor end face clearance design tolerance zone.

[0018] The technical effects of this invention are as follows: This invention proposes a method for designing the rotor end face clearance of a cycloidal pump. The minimum value of the rotor end face clearance is obtained through a solidified structural simulation modeling equivalent method and post-processing. The maximum value of the rotor end face clearance is then obtained by combining design parameters and performance numerical calculations, thereby determining the optimal tolerance range for the end face clearance. This method simultaneously evaluates the rotor end face wear resistance and flow loss due to the end face clearance of the cycloidal pump, finding a balance between these two conflicting factors. This enables a shift from experience-driven design to forward analysis design in critical dimension control of the pump, improving the reliability of the product under service conditions. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 Flowchart for designing and calculating the end face clearance of a cycloidal pump rotor.

[0021] Figure 2 This is a flowchart for structural deformation analysis.

[0022] Figure 3 This is a flowchart for analyzing flow loss in the end face gap.

[0023] Figure 4 This is a schematic diagram showing the overall deformation of the pump magnified 10 times.

[0024] Figure 5 Surf deformation occurs on both sides of cavity B.

[0025] Figure 6 The curves show the performance variation under different single-sided end face gaps. Detailed Implementation

[0026] This section describes embodiments of the present invention, used to explain and illustrate the technical solutions of the present invention. Unless otherwise specified, the embodiments and features described herein can be combined with each other.

[0027] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating directions or positional relationships, are given in the accompanying drawings and are used only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or device referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include more than one of those features. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0028] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integrated connections; they can refer to mechanical connections or point connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0029] Example 1: A method for designing the rotor end face clearance of a cycloidal pump involves taking an initial three-dimensional model of the cycloidal pump designed using historical experience as input, and then performing the following steps: S1: Calculate the structural deformation of the pump under mechanical and thermal loads; S2: Obtain the minimum end face clearance for rotor wear resistance; S3: Analyze the flow loss through the end face gap; S4: Evaluate pump flow performance; S5: Obtain the maximum end face clearance of the rotor; S6: Determine the rotor end face design tolerance; If the traffic performance in S4 does not meet the requirements of the upper-layer system, S1~S4 will be executed repeatedly.

[0030] Furthermore, S1 specifically refers to: S11: To avoid wear between the rotor and the diaphragm, the rotor and the diaphragm should not come into contact under any combination of loads (such as disc spring force, pressure and temperature). Therefore, the inner rotor can be deleted, and the housing, diaphragm, eccentric sleeve, diaphragm positioning pin, and pump core limiting parts (if any) that contribute significantly to the axial stiffness of the cycloidal pump can be retained. The remaining parts can be deleted to complete the simplification of the cycloidal pump's three-dimensional model. S12: In addition to strain deformation caused by bearing force, the diaphragm also undergoes lateral deformation caused by torque, and the latter accounts for a large proportion of the total deformation. Therefore, the maximum value of the radial dimension tolerance of the shell, pump core, shaft, bearing and locating pin is taken to correct the cycloidal pump three-dimensional model. S13: In Abaqus software, the rotor rotation sweep surface is marked on both sides of each partition, and a surf (unit surface set) is created to facilitate post-processing calculation of the end face gap. S14: Establish a Tie (binding connection) between the bearing and the partition. If the shaft is limited by a retaining ring, establish a Coupling (multi-point coupling connection) between the limiting surfaces of the shaft and the partition. Establish a surface-to-surface contact (surface-to-surface contact relationship) between the remaining surfaces and assign contact properties. The contact normal adopts "Hard" Contact (hard contact algorithm), and the contact tangential adopts Penalty (penalty function method) and sets the friction coefficient to ensure that there is no rigid body running. This completes the definition of the connection relationship of the cycloidal pump. S15: Create two load steps, the load step type is Coupled temp-displacement (thermal coupling analysis). Step 1: Apply the disc spring force as a uniform pressure to the disc spring seat. Step 2: Apply the design pressure and temperature of each functional cavity to the inlet and outlet positions of the partitions on both sides of each functional cavity. The constraints are set according to the installation state of the performance test. S16: Open Nlgeom, set Automatic stabilization to Specify damping factor to improve the convergence of the simulation analysis, submit the calculation to the Standard (implicit solver) solver, and output the stress field, strain field and displacement field of the cycloidal pump.

[0031] S2 specifically refers to: First, compare the relationship between the equivalent stress of the components and the yield strength of their materials. If the stress is greater than the yield strength, plasticity curve data needs to be added to the material constitutive parameters for simulation again to extract the structural deformation. Otherwise, the structural deformation can be extracted directly. Secondly, extract the axial deformation on the surf of the pair of inner and outer rotors established in step S13. The minimum end face clearance required for rotor wear resistance = abs (maximum value of both surf surfaces minus minimum value). Finally, the maximum value among the minimum wear-resistant end face clearances of all rotors in the cycloidal pump is taken as the minimum rotor end face clearance in the overall pump design.

[0032] Furthermore, S3 specifically refers to: S31: Using CAD software, the inner rotor is appropriately scaled and the rotation center is adjusted to the center of the outer rotor to complete the correction of the three-dimensional model; the three-dimensional model is simplified, the chamfer of the oil distribution plate area is removed, and the fluid domain of the oil distribution plate is extracted.

[0033] S32: Use the CAD import function in AMESim to import the CAD geometry into a 3D model (distribution plate fluid domain, inner and outer rotors). Start the 1D Modeling mode, select the Generic gerotorpump type under Volumetric pump, and identify the contours of the inner and outer gears, the inlet and outlet areas of the distribution plate, and the volume of the cycloidal pump, converting the 3D model into a 1D model. For the 1D model of the cycloidal pump, select the HCDGPEXT1 (hydraulic cycloidal pump) component with a clearance leakage interface from the hydraulic reservoir.

[0034] S33: The clearance leakage of the cycloidal pump includes two parts: end face clearance and radial clearance. The radial clearance leakage of the cycloidal pump has already been considered in the 3D model in S31, so only the end face clearance leakage model needs to be established. The end face clearance leakage path of the cycloidal pump includes two parts: one part is leakage from the inner rotor tooth root circle to the bearing cavity, and the other part is leakage from the outer rotor tooth root circle to the outer rotor outer circle. Therefore, the end face clearance leakage can be calculated based on the "gap flow between perforated disks" in fluid mechanics. The HCDVECVORG0 (hydraulic vector orifice) element is used to model the end face clearance at both ends of the cycloidal pump; simultaneously, the H3VECNODE1 (hydraulic vector 3 interface) element is used to transmit the pressure of each chamber of the cycloidal pump to the HCDVECVORG0 (hydraulic vector orifice) element for leakage calculation.

[0035] The leakage from the high-pressure chamber of the cycloidal pump to the bearing chamber is:

[0036] in, —The end face clearance of the inner rotor, in meters; —Pressure difference between the liquid in the high-pressure chamber and the bearing chamber (with pressure equal to the pump inlet) of the cycloidal pump, in Pa; —The dynamic viscosity of the oil, Pa·s; —Rotor tooth root circle radius, m; — Rotation radius, m.

[0037] The leakage from the high-pressure chamber of the cycloidal pump to the outer circumference of the outer rotor is:

[0038] in, —The radius of the outer circle of the outer rotor; — The radius of the root circle of the external rotor teeth.

[0039] S34: Select the PM000 (motor) component from the mechanical library, the CONS00 (fixed value signal) component and the SIGMOAVAVG0 (moving average) component from the signal library, and the tank (oil tank), FP04 (oil property) component and QT001 (flow meter) component from the hydraulic library to establish a complete one-dimensional simulation model of the cycloidal pump system. Set the physical property parameters and boundary conditions of each component and perform simulation calculations.

[0040] S4 specifically involves: starting with the minimum end-face gap obtained in S2, gradually increasing the end-face gap, and plotting performance curves for different gaps. If the flow rate at the starting point (minimum gap) does not meet the design flow rate requirements, the design scheme needs to be modified, and S1~S4 need to be repeated.

[0041] S5 specifically refers to finding the end face gap value corresponding to the design requirement flow rate on the performance curve, and using it as the maximum end face gap value.

[0042] S6 specifically refers to the combination of the upper and lower limit values ​​of S2 and S5, forming the rotor end face clearance design tolerance zone. If design margin needs to be considered, the tolerance range can be appropriately narrowed inward.

[0043] Example 2: A method for designing the end face clearance of a cycloidal pump rotor includes the following steps: Furthermore, S1 specifically refers to: S11: Simplify the 3D model of the cycloidal pump. Delete the inner rotor, retain the casing, diaphragm, eccentric sleeve, diaphragm positioning pin, and pump core limiting component (if any) that contribute significantly to axial stiffness, and delete the remaining components. S12: Correct the 3D model of the cycloidal pump. Set the radial clearance between the housing and the pump core to 0.05mm; the radial clearance between the shaft and the bushing to 0.1mm; the radial clearance between the shaft and the partition to 0.4mm; and the radial clearance between the partition and its locating pin to 0.16mm. S13: Divide the side of the partition. Imprint the rotor rotation sweep area in Abaqus software and create a surf (set of element surfaces); S14: Define the connection relationships of the cycloidal pump. Establish a Tie (bonding connection) between the bearing and the partition. If the shaft is limited by a retaining ring, establish a Coupling (multi-point coupling connection) between the limiting surfaces of the shaft and the partition. Establish a surface-to-surface contact (surface-to-surface contact) relationship between the remaining surfaces and assign contact properties. The contact normal adopts "Hard" Contact (hard contact algorithm), and the contact tangential adopts Penalty (penalty function method) and sets the friction coefficient. S15: Define constraint boundaries and loads. Create two Coupled temp-displacement load steps, where Step 1 applies a disc spring force of 1800N; Step 2 applies the design pressure and temperature of each functional cavity to the inlet and outlet positions of the partitions on both sides of each functional cavity (e.g., inlet pressure of 200Kpa and temperature of 180°C for cavity B), and the constraints are set according to the installation state of the performance test. S16: Define the Standard (implicit solver) solver parameters. Open Nlgeom, set Automaticstabilization to Specify damping factor, submit the calculation, and output the displacement field of the cycloidal pump. See details. Figure 4 Judging from the deformation diagram, cavity B is relatively severely deformed.

[0044] S2: Extract the axial deformation on the surf surface of a pair of inner and outer rotors (e.g., cavity B) established in step S13. The minimum end face clearance required for rotor wear resistance = abs (maximum value of both surf surfaces minus minimum value). The minimum end face clearance for cavity B is 0.0616mm. See details... Figure 5 Meanwhile, the minimum end face clearance of other functional chambers was taken, and the minimum end face clearance of the rotor in the overall pump design was finally determined to be 0.062mm (this value is 0.0616 rounded up to three decimal places).

[0045] Furthermore, S3 specifically refers to: S31: Using CAD software, the inner rotor is appropriately scaled to make the minimum gap between the inner and outer rotors 0.03mm, and the rotation center is adjusted to the center of the outer rotor. The chamfer of the oil distribution plate area is removed, and the fluid domain of the oil distribution plate is extracted.

[0046] S32: Use the CAD import function in AMESim to import the CAD geometry into a 3D model (distribution plate fluid domain, inner and outer rotors). Start the 1D Modeling mode, select the Generic gerotorpump type in the Volumetric pump category, identify the contours of the inner and outer gears, the inlet and outlet areas and volume of the distribution plate, manually set the number of teeth of the outer rotor to 7, click Sketch generation to generate a 1D model of the cycloidal pump, and select the HCDGPEXT1 (hydraulic cycloidal pump) component with a clearance leakage interface in the hydraulic library as the cycloidal pump sub-model.

[0047] S33: Establish an end-face clearance leakage model, where part of the leakage originates from the inner rotor tooth root circle to the bearing cavity, and part originates from the outer rotor tooth root circle to the outer rotor outer circle. Use the HCDVECVORG0 (hydraulic vector hole) element to model the end-face clearance at both ends of the cycloidal pump. Simultaneously, use the H3VECNODE1 (hydraulic vector 3 interface) element to transmit the pressure from each chamber of the cycloidal pump to the HCDVECVORG0 (hydraulic vector hole) element for leakage calculation.

[0048] The leakage from the high-pressure chamber of the cycloidal pump to the bearing chamber is:

[0049] in, —The end face clearance of the inner rotor, in meters; —Pressure difference between the liquid in the high-pressure chamber and the bearing chamber (with pressure equal to the pump inlet) of the cycloidal pump, in Pa; —The dynamic viscosity of the oil, Pa·s; —Rotor tooth root circle radius, m; — Rotation radius, m.

[0050] The leakage from the high-pressure chamber of the cycloidal pump to the outer circumference of the outer rotor is:

[0051] in, —The radius of the outer circle of the outer rotor; — The radius of the root circle of the external rotor teeth.

[0052] S34: Select the motor PM000 component from the mechanical library, the CONS00 (fixed value signal) component from the signal library, the SIGMOVAVG0 (moving average) component, the tank (oil tank) component from the hydraulic library, the oil property FP04 (oil property) component, and the flow meter QT001 (flow meter) component to establish a complete one-dimensional simulation model of the cycloidal pump system.

[0053] S4: Set the oil density to 937.2 kg / m³ in the FP04 element for oil properties. 3 The viscosity is 0.01040 Pa·s, and the hydraulic oil index is 1. In the cycloidal pump HCDGPEXT1 element, the radial clearance of the cycloidal pump is set to 0 to avoid redundant consideration of radial leakage. In the 3-port H3VECNODE1 element, the vector size is set to 7. In the motor PM000 element, the speed is set to 12140 rev / min. The pump inlet tank (oil tank) element pressure is set to atmospheric pressure. The pump outlet tank (oil tank) element pressure is set to 0.2 MPa. The end-face clearance leakage includes two parts: the inner rotor tooth root radius R... irThe diameter is 10.2mm, and the shaft radius R is... s The radius R of the outer circle of the outer rotor is 6mm. ext The radius of the outer rotor tooth root circle is 17.85mm. or The clearance is 15.8mm. Therefore, combining the end-face clearance leakage formula, the AMEsimHCDVECVORG (hydraulic vector orifice) element calculation formula, and considering double-end leakage, the vector size is set to 7, the clearance width to 2π, and the length to 0.2653 in end-face leakage HCDVECVORG (hydraulic vector orifice) element 1, and the vector size is set to 7, the clearance width to 2π, and the length to 0.0610 in end-face leakage HCDVECVORG (hydraulic vector orifice) element 2. The clearance values ​​are all based on the minimum end-face clearance obtained, and the end-face clearance is gradually increased to plot performance curves under different clearances. If the flow rate at the starting point (minimum clearance) does not meet the design flow rate requirements, the design scheme needs to be revised, and S1~S4 needs to be repeated.

[0054] S5: The design flow rate is 15L / min, and the corresponding single-sided end face clearance is 0.045mm. The calculated double-sided rotor end face clearance is 0.09mm, and this value is taken as the maximum end face clearance value.

[0055] S6: Combining the upper and lower limit values ​​of S2 and S5, the rotor end face clearance design tolerance zone is 0.062~0.09mm. See details... Figure 6 .

[0056] The above description is merely a specific embodiment of the present invention, providing a detailed description of the invention. Parts not covered herein are conventional techniques. However, the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. The scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for designing the end face clearance of a cycloidal pump rotor, characterized in that, Using the initial 3D model of the cycloidal pump designed based on historical experience as input, the following steps are then performed: S1, calculate the structural deformation of the pump under mechanical and thermal loads; S2, to obtain the minimum wear-resistant end face clearance of the rotor; S3, analyze the flow loss through the end face gap; S4, evaluate pump flow performance; if the flow performance does not meet the requirements of the upper system, repeat S1~S4 until it does; S5, to obtain the maximum end face clearance of the rotor; S6, determine the rotor end face design tolerance.

2. The method for designing the rotor end face clearance of a cycloidal pump according to claim 1, characterized in that, S1 specifically includes the following steps: S11, simplified initial 3D model of cycloidal pump; S12, take the maximum value of the radial dimension tolerance of the housing, pump core, shaft, bearing and locating pin, and correct the cycloidal pump three-dimensional model; S13, Imprint the rotor rotation sweep surface on both sides of each partition, and create a set of unit surfaces; S14, establish a binding connection between the bearing and the partition. If the shaft is limited by a retaining ring, establish a multi-point coupling connection between the limiting surfaces of the shaft and the partition, and establish a surface-to-surface contact relationship between the remaining surfaces and assign contact properties. S15, create two load steps, the rotation load step type is thermo-coupling analysis, then first apply the disc spring force as a uniform pressure to the disc spring seat, and then apply the design pressure and temperature of the functional cavity to the inlet and outlet positions of the partitions on both sides of each functional cavity respectively, and constrain according to the performance test installation state. S16 sets the large deformation as a damping factor to increase the convergence of the simulation analysis, submits the implicit solver for calculation, and outputs the stress field, strain field and displacement field of the cycloidal pump.

3. The method for designing the rotor end face clearance of a cycloidal pump according to claim 2, characterized in that, In S11, the shell, diaphragm, eccentric sleeve, diaphragm positioning pin and pump core limiting component are retained in the initial three-dimensional model of the cycloidal pump, while other components, including the inner rotor, are deleted, thus completing the simplification of the initial three-dimensional model of the cycloidal pump.

4. A method for designing the rotor end face clearance of a cycloidal pump according to claim 2, characterized in that, In S14, the contact normal direction adopts the Hard Contact algorithm, and the contact tangential direction adopts the Penalty penalty function method and sets the friction coefficient to ensure that there is no rigid body operation, thus completing the definition of the cycloidal pump connection relationship.

5. The method for designing the rotor end face clearance of a cycloidal pump according to claim 1, characterized in that, S2 specifically refers to: S21. Compare the relationship between the equivalent stress of the component and the yield strength of the material. If the equivalent stress of the component is greater than the yield strength, the plasticity curve data needs to be added to the material constitutive parameters for simulation again to extract the structural deformation. Otherwise, the structural deformation is extracted directly. S22, extract the axial deformation of a pair of inner and outer rotors on the unit surface to obtain the minimum end face clearance required for rotor wear resistance; S23, take the maximum value among the minimum wear-resistant end face clearances of all rotors of the cycloidal pump as the minimum rotor end face clearance in the overall pump design.

6. The method for designing the rotor end face clearance of a cycloidal pump according to claim 1, characterized in that, S3 specifically refers to: S31. Use CAD software to scale the inner rotor and adjust the rotation center to the center of the outer rotor to complete the correction of the three-dimensional model; simplify the three-dimensional model, remove the chamfer of the oil distribution plate area, and extract the fluid domain of the oil distribution plate. S32, import the CAD 3D model of the oil distribution plate fluid domain and the inner and outer rotors, identify the inner and outer gear contours, oil distribution inlet and outlet areas and volumes of the cycloidal pump, and convert the CAD 3D model into a 1D model. S33, calculate the leakage of the end face gap based on the "slit flow between perforated disks" in fluid mechanics; S34. Select motor components from the data machinery library, fixed signal components and moving average components from the signal library, and oil tank components, oil property components and flow meter components from the data hydraulic library to establish a complete one-dimensional simulation model of the cycloidal pump system; set the physical property parameters and boundary conditions of each component for simulation calculation.

7. The method for designing the rotor end face clearance of a cycloidal pump according to claim 6, characterized in that, In S33, a hydraulic vector hole element is used to model the end face clearance at both ends of the cycloidal pump; simultaneously, a hydraulic vector 3 interface element is used to transmit the pressure of each chamber of the cycloidal pump to the hydraulic vector hole element for leakage calculation; the leakage from the high-pressure chamber of the cycloidal pump to the bearing chamber is: in, It is the end face clearance of the inner rotor; It is the pressure difference between the high-pressure chamber and the bearing chamber of the cycloidal pump; It is the dynamic viscosity of the oil; It is the radius of the rotor tooth root circle; It is the radius of the pivot; The leakage from the high-pressure chamber of the cycloidal pump to the outer circumference of the outer rotor is: in, It is the radius of the outer circle of the outer rotor; It is the radius of the root circle of the outer rotor teeth.

8. The method for designing the rotor end face clearance of a cycloidal pump according to claim 1, characterized in that, S4 specifically refers to: Starting with the minimum end face clearance obtained by S2, gradually increase the end face clearance and plot the performance curves under different clearances.

9. The method for designing the rotor end face clearance of a cycloidal pump according to claim 1, characterized in that, S5 specifically refers to: On the performance curve, find the end face gap value corresponding to the design requirement flow rate, and use it as the maximum end face gap value.

10. The method for designing the rotor end face clearance of a cycloidal pump according to claim 1, characterized in that, S6 specifically refers to: The minimum end face clearance obtained by combining S2 and the maximum end face clearance obtained by S5 form the rotor end face clearance design tolerance zone.

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