A method for predicting hydraulic slide valve leakage considering non-ideal surface factors

Abstract

The present invention provides a method for predicting leakage of a hydraulic slide valve taking into account non-ideal surface factors, comprising the following steps: step 1, extracting data from a hydraulic slide valve design drawing to reconstruct the non-ideal surface of the hydraulic slide valve; step 2, constructing a hydraulic slide valve entity model based on the non-ideal surface of the hydraulic slide valve; step 3, extracting a hydraulic leakage channel from the hydraulic slide valve entity model; step 4, performing oil leakage analysis on the hydraulic leakage channel to obtain a hydraulic slide valve leakage prediction result. The present invention constructs a hydraulic slide valve entity model after reconstructing the non-ideal surface of the hydraulic slide valve, taking into account the influence of the error of the non-ideal surface factor on the internal leakage of the hydraulic slide valve, and is suitable for leakage prediction of precision slide valves, providing a reference for improving the processing quality of precision slide valves.

Description

Technical Field

[0001] The invention relates to the field of hydraulic valve prediction, and in particular to a hydraulic slide valve leakage prediction method taking non-ideal surface factors into consideration. Background Art

[0002] As the core component of the electro-hydraulic servo control system, the performance and reliability of the precision slide valve are related to the performance and safety of the entire hydraulic control system. Due to the relative movement between the precision slide valves, there must be a matching gap. When there is a pressure difference at both ends of the matching gap or the walls that make up the gap move relative to each other, the oil in the matching gap will flow, causing oil leakage, which will directly affect the performance parameters such as the control accuracy and frequency response characteristics of the precision slide valve.

[0003] At present, most of the calculation models for predicting internal leakage of precision sliding valves are based on the assumption that the valve core and the valve sleeve are ideal smooth cylindrical surfaces. Due to the existence of processing errors, the assembly interface between the valve core and the valve sleeve is not an ideal smooth surface, but has random and irregular geometric morphological characteristics as well as multiple error components such as roughness, waviness and form and position errors. These morphological errors are manifested in the form of various errors of the column on a macro scale, including five shapes: cone, hourglass, barrel, banana and petal.

[0004] Relevant literature on the prediction of internal leakage of sliding valves, such as "He Yuming, Peng Likun, Song Fei. Simulation study on the mid-position internal leakage of hydraulic sliding valves based on AMESim [J]. Hydraulics and Pneumatics, 2018, No. 321 (05): 74-80." Using AMESim software, a precision sliding valve internal leakage fault simulation platform was built, and the effects of hydraulic system pressure, sliding valve pair clearance height, covering amount, fluid viscosity, valve core diameter and eccentricity on internal leakage and system performance were comprehensively considered, and the main influencing factors of internal leakage in the mid-position state were obtained; another example is "Xue Xiaohu. Analysis of fluid leakage characteristics in hydraulic system gaps [J]. Journal of Mechanical Engineering, 2004 (06): 75-80." Through the analysis of fluid leakage in various gaps in the hydraulic system, a mathematical model for the fluid leakage in the gap that comprehensively considers the system's working pressure, temperature and the amount of mixed air is proposed.

[0005] The above-mentioned literature has conducted a certain degree of research in the field of internal leakage of sliding valves, and obtained analytical and numerical solutions to the internal leakage of sliding valves. However, their calculation models are all based on the premise that the valve core and valve sleeve are ideal smooth cylindrical surfaces, and the influence of morphological errors on internal leakage is not considered. Summary of the invention

[0006] The purpose of the present invention is to provide a hydraulic slide valve leakage prediction method taking into account non-ideal surface factors. After reconstructing the non-ideal surface of the hydraulic slide valve, a hydraulic slide valve physical model is constructed. The influence of the error of the non-ideal surface factor on the internal leakage of the hydraulic slide valve is taken into account. The method is suitable for leakage prediction of precision slide valves and provides a reference for improving the processing quality of precision slide valves.

[0007] The technical solution for achieving the purpose of the present invention is as follows:

[0008] The present invention provides a method for predicting leakage of a hydraulic slide valve taking into account non-ideal surface factors, comprising the following steps:

[0009] Step 1: extract data from the hydraulic slide valve design drawing to reconstruct the non-ideal surface of the hydraulic slide valve;

[0010] Step 2: constructing a hydraulic slide valve entity model based on the non-ideal surface of the hydraulic slide valve;

[0011] Step 3, extracting the hydraulic leakage flow channel from the hydraulic slide valve physical model;

[0012] Step 4: Perform oil leakage analysis on the hydraulic leakage channel to obtain a hydraulic slide valve leakage prediction result.

[0013] As a further limitation of the present invention, the step 1 comprises:

[0014] Extracting the dimension information and tolerance information of the valve core and the valve sleeve in the hydraulic slide valve from the design drawing of the hydraulic slide valve;

[0015] Determine the coefficient matrix of the correction function in the Chebyshev / Fourier model as the non-ideal surface according to the extracted tolerance information of the valve core and the valve sleeve;

[0016] The discretized point cloud model of the non-ideal surface is generated by combining the size information of the valve core and the valve sleeve;

[0017] The discretized point cloud model is reversely modeled to obtain a reconstruction of the non-ideal surface of the hydraulic slide valve.

[0018] As a further limitation of the present invention, the step of determining the coefficient matrix of the correction function in the Chebyshev / Fourier model as the non-ideal surface according to the extracted tolerance information of the valve core and the valve sleeve comprises:

[0019] Decomposition of topographic error of non-ideal surface of hydraulic slide valve;

[0020] Analyze the actual curved surfaces of valve core and valve sleeve based on Chebyshev / Fourier model;

[0021] Acquire small change data on the size, position and direction of the cylinder corresponding to the valve core and the valve sleeve according to the actual curved surface;

[0022] The correction coefficients corresponding to the correction functions of different cylinders are adjusted based on the slight change data to obtain a coefficient matrix.

[0023] As a further limitation of the present invention, the step of determining the coefficient matrix of the correction function in the Chebyshev / Fourier model as the non-ideal surface according to the extracted tolerance information of the valve core and the valve sleeve comprises:

[0024] Step (1) uses formula (1) to decompose the topographic error of the non-ideal surface of the precision slide valve;

[0025]

[0026] In formula (1), W is the reconstructed surface; G is the basis function matrix; A is the coefficient matrix;

[0027] In step (2), the Chebyshev / Fourier model is used as the basis function set of the basis function matrix. Under the Chebyshev / Fourier model, the surface morphology of the cylinder corresponding to the actual valve core and the valve sleeve is expressed as:

[0028]

[0029] In formula (2), r is the mathematical model of the actual cylindrical surface morphology; R is the nominal radius of the ideal cylinder, and the deviation between R and r is required to be much smaller than R; T i (ζ) is the Chebyshev polynomial of the second kind of order i; a ij and b ij Indicates the coefficient of deviation of the actual cylinder;

[0030] Step (3) Optimize formula (2) to obtain formula (3):

[0031] r(z,θ)=R+F c (z,θ)a Formula (3)

[0032] In formula (3), F c (z,θ) is the row vector of the function of z and θ multiplied by the column vector of coefficients a; the elements of F are T i and cos(jθ) or sin(jθ) individually; F c (z,θ) is expressed as:

[0033]

[0034] In formula (4), is the normalized z coordinate value, ζ is used as the parameter of T, T represents the second kind of Chebyshev polynomial; five functions represent small changes in the size, position and direction of the cylinder, among which:

[0035] Function T in formula (4) 0cos(0×θ) is the constant 1, function T 0 The coefficient of cos(0×θ) represents the deviation between the radius of the actual cylinder and the radius of the ideal cylinder; the function T in formula (4) 0 cos(θ)=cos(θ), function T 0 The coefficient of cos(θ) represents the small displacement of the cylinder in the x direction; the function T in formula (4) 0 sin(θ)=sin(θ), function T 0 The coefficient of sin(θ) represents the small displacement of the cylinder in the y direction; if the cylinder is tilted about its center, the function T 1 The coefficient of cos(θ) represents the displacement of the top of the cylinder in the +x direction and the bottom in the -x direction simultaneously; the function T 1 The coefficient of sin(θ) represents the displacement of the top of the cylinder in the +y direction and the bottom in the -y direction simultaneously;

[0036] Step (4): The five functions in step (3) correspond to five different cylinders, and the correction terms corresponding to the five different cylinders are: T 1 (ζ) corresponds to the cone; |T 2 (ζ)| corresponds to the hourglass shape; -|T 2 (ζ)| corresponds to barrel shape; T 2 (ζ)cos(θ),T 2 (ζ)sin(θ) corresponds to the banana shape; T 0 (ζ)cos(nθ),T 0 (ζ)sin(nθ) corresponds to the petal shape; the coefficients corresponding to different correction terms are adjusted to obtain the coefficient matrix of the correction function to control the degree of deviation of different cylinder forms.

[0037] As a further limitation of the present invention, the inverse modeling of the discretized point cloud model to obtain the reconstruction of the non-ideal surface of the hydraulic slide valve includes:

[0038] Importing the point cloud data in the discretized point cloud model into three-dimensional CAD software;

[0039] According to the reverse modeling principle of "point-line-surface", section curves and multi-section surfaces are generated in sequence in the three-dimensional CAD software to complete the construction of the non-ideal surface of the hydraulic slide valve.

[0040] As a further limitation of the present invention, the step 2 comprises:

[0041] Based on the constructed non-ideal surface of the hydraulic slide valve, the entity of the hydraulic slide valve is digitally reconstructed to obtain a hydraulic slide valve entity model.

[0042] As a further limitation of the present invention, the step three comprises:

[0043] Performing Boolean operation on the hydraulic slide valve entity model to extract non-ideal geometric flow channels for oil leakage;

[0044] The extracted non-ideal geometric flow channel is processed.

[0045] As a further limitation of the present invention, the extracting of non-ideal geometric flow paths for oil leakage by performing Boolean operation on the hydraulic slide valve entity model comprises:

[0046] Pre-processing the geometry of the hydraulic slide valve entity model, performing Boolean subtraction operation on the hydraulic slide valve entity model in 3D CAD software, extracting non-ideal geometric flow channels of oil leakage, and naming and converting the formats of all boundaries of the flow channel entities in the hydraulic slide valve entity model in SCDM;

[0047] The mesh of the hydraulic slide valve entity model is pre-processed by selecting the watertight workflow in Fluent Meshing to mesh the hydraulic slide valve entity model.

[0048] As a further limitation of the present invention, the step 4 comprises:

[0049] The hydraulic leakage channel is analyzed for oil leakage based on Fluent to obtain a hydraulic slide valve leakage prediction result.

[0050] Compared with the prior art, the present invention has the following beneficial effects:

[0051] 1. The present invention constructs a non-ideal surface of a hydraulic slide valve, and describes the regular shape characteristics of the matching surface of the hydraulic slide valve at the macro level, including five shapes: cone, hourglass, barrel, banana and petal; at the micro level, the irregular detailed structure of the matching surface is depicted, and the parameter perturbations such as dimensional error, shape error and matching length caused by machining errors in the machining process of the hydraulic slide valve are comprehensively considered, and a geometric basis is provided for the subsequent performance prediction of the hydraulic slide valve.

[0052] 2. The present invention simulates the influence of various factors such as the dimensional tolerance, cylindricity tolerance, fitting length of the valve core and valve sleeve, as well as the pressure difference and fluid temperature on both sides of the slide valve on the zero-position internal leakage of the hydraulic slide valve, and obtains the influence relationship between each factor and the zero-position internal leakage of the hydraulic slide valve, providing a reference for improving the processing quality of the precision slide valve. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 A flow chart of a method for predicting leakage of a hydraulic slide valve taking into account non-ideal surface factors provided by the present invention;

[0054] Figure 2A simulation diagram of a hydraulic slide valve leakage prediction method considering non-ideal surface factors provided by the present invention;

[0055] Figure 3 A schematic diagram of actual surface discretization taking cone error as an example in a hydraulic slide valve leakage prediction method taking non-ideal surface factors into consideration provided by the present invention;

[0056] Figure 4 A reverse modeling flow chart taking cone error as an example in a hydraulic slide valve leakage prediction method taking non-ideal surface factors into consideration provided by the present invention;

[0057] Figure 5 A schematic diagram of the pre-processing of the model for the zero-position internal leakage simulation of the precision hydraulic slide valve provided by the present invention;

[0058] Figure 6 This is a comparative schematic diagram of the zero-position internal leakage of a precision hydraulic slide valve under different cylinder error forms considered in the present invention;

[0059] Figure 7 This is a schematic diagram of the influence of various factors on the zero-position internal leakage of the precision hydraulic slide valve considered by the present invention. DETAILED DESCRIPTION

[0060] The present invention is described in detail below in conjunction with the various embodiments shown in the accompanying drawings, but it should be noted that these embodiments are not limitations of the present invention, and any equivalent transformations or substitutions in functions, methods, or structures made by ordinary technicians in the field based on these embodiments are all within the scope of protection of the present invention.

[0061] The design concept of the embodiment of the present invention is: considering the prediction of zero-position internal leakage of precision hydraulic slide valves with different morphologies, based on the precision hydraulic slide valve structure / process design model, first, extract the size information and tolerance information of the precision hydraulic slide valve from the macro and micro scales respectively; secondly, select the correction item corresponding to the cone error according to the mathematical method, and determine the coefficient matrix of the non-ideal surface basis function in combination with the design tolerance information of the precision hydraulic slide valve, and then generate a point cloud model of the non-ideal surface in combination with the size information of the precision hydraulic slide valve; thirdly, use the discretized point cloud model to realize the digital expression of the physical entity of the precision hydraulic slide valve according to the inverse modeling method; thirdly, based on the three-dimensional solid model, use Boolean operations to extract the geometric path of the oil leakage of the precision hydraulic slide valve; finally, use the CFD method to carry out the simulation analysis of the oil leakage of the precision hydraulic slide valve with the fusion of geometric and physical quantities.

[0062] See also Figure 1 The embodiment of the present invention provides a method for predicting leakage of a hydraulic slide valve taking into account non-ideal surface factors, comprising the following steps:

[0063] Step 1: Extract data from the hydraulic slide valve design drawing to reconstruct the non-ideal surface of the hydraulic slide valve.

[0064] Specifically, the above step 1 of the embodiment of the present invention includes:

[0065] (1) Extract the dimension and tolerance information of the valve core and valve sleeve in the hydraulic slide valve from the design drawing of the hydraulic slide valve.

[0066] (2) Determine the coefficient matrix of the correction function in the Chebyshev / Fourier model as the non-ideal surface according to the extracted tolerance information of the valve core and the valve sleeve.

[0067] The above-mentioned method of determining the coefficient matrix of the correction function in the Chebyshev / Fourier model as the non-ideal surface according to the tolerance information of the valve core and the valve sleeve extracted in the embodiment of the present invention includes:

[0068] Decomposition of topographic error of non-ideal surface of hydraulic slide valve;

[0069] Analyze the actual curved surfaces of valve core and valve sleeve based on Chebyshev / Fourier model;

[0070] Obtain the data of slight changes in the size, position and direction of the cylinders corresponding to the valve core and valve sleeve based on the actual curved surface;

[0071] The correction coefficients corresponding to the correction functions of different cylinders are adjusted based on the slightly changed data to obtain a coefficient matrix.

[0072] More specifically, the coefficient matrix of the correction function in the Chebyshev / Fourier model as the non-ideal surface is determined according to the tolerance information of the valve core and the valve sleeve, including:

[0073] Step (1), using formula (1) to decompose the topographic error of the non-ideal surface of the precision slide valve;

[0074]

[0075] In formula (1), W is the reconstructed surface; G is the basis function matrix; A is the coefficient matrix;

[0076] Step (2), using the Chebyshev / Fourier model as the basis function set of the basis function matrix, the surface morphology of the cylinder corresponding to the actual valve core and valve sleeve under the Chebyshev / Fourier model is expressed as:

[0077]

[0078] In formula (2), r is the mathematical model of the actual cylindrical surface morphology; R is the nominal radius of the ideal cylinder, and the deviation between R and r is required to be much smaller than R; T i (ζ) is the Chebyshev polynomial of the second kind of order i; a ijand b ij Indicates the coefficient of deviation of the actual cylinder;

[0079] Step (3), optimize formula (2) to obtain formula (3):

[0080] r(z,θ)=R+F c (z,θ)a Formula (3)

[0081] In formula (3), F c (z,θ) is the row vector of the function of z and θ multiplied by the column vector of coefficients a; the elements of F are T i and cos(jθ) or sin(jθ) individually; F c (z,θ) is expressed as:

[0082]

[0083] In formula (4), is the normalized z coordinate value, ζ is used as the parameter of T, T represents the second kind of Chebyshev polynomial; five functions represent small changes in the size, position and direction of the cylinder, among which:

[0084] Function T in formula (4) 0 cos(0×θ) is the constant 1, function T 0 The coefficient of cos(0×θ) represents the deviation between the radius of the actual cylinder and the radius of the ideal cylinder; the function T in formula (4) 0 cos(θ)=cos(θ), function T 0 The coefficient of cos(θ) represents the small displacement of the cylinder in the x direction; the function T in formula (4) 0 sin(θ)=sin(θ), function T 0 The coefficient of sin(θ) represents the small displacement of the cylinder in the y direction; if the cylinder is tilted about its center, the function T 1 The coefficient of cos(θ) represents the displacement of the top of the cylinder in the +x direction and the bottom in the -x direction simultaneously; the function T 1 The coefficient of sin(θ) represents the displacement of the top of the cylinder in the +y direction and the bottom in the -y direction simultaneously;

[0085] The five functions in step (4) and step (3) correspond to five different cylinders, and the correction terms corresponding to the five different cylinders are: T 1 (ζ) corresponds to the cone; |T 2 (ζ)| corresponds to the hourglass shape; -|T 2 (ζ)| corresponds to barrel shape;

[0086] T 2 (ζ)cos(θ),T2 (ζ)sin(θ) corresponds to the banana shape; T 0 (ζ)cos(nθ),T 0 (ζ)sin(nθ) corresponds to the petal shape; the coefficients corresponding to different correction terms are adjusted to obtain the coefficient matrix of the correction function to control the degree of deviation of different cylinder forms.

[0087] (3) The discretized point cloud model of the non-ideal surface is generated by combining the dimensional information of the valve core and the valve sleeve.

[0088] (4) The discretized point cloud model is reverse modeled to obtain the reconstruction of the non-ideal surface of the hydraulic slide valve.

[0089] Specifically, the above-mentioned reverse modeling of the discretized point cloud model obtains the reconstruction of the non-ideal surface of the hydraulic sliding valve, including: importing the point cloud data in the discretized point cloud model into the three-dimensional CAD software; according to the reverse modeling principle of "point-line-surface", the cross-sectional curves and multi-sectional surfaces are generated in the three-dimensional CAD software in sequence to complete the construction of the non-ideal surface of the hydraulic sliding valve.

[0090] The embodiment of the present invention constructs a non-ideal surface of a hydraulic sliding valve, and describes the regular shape characteristics of the mating surface of the hydraulic sliding valve at a macroscopic level, including five shapes: cone, hourglass, barrel, banana and petal; at a microscopic level, it depicts the irregular detailed structure of the mating surface, and comprehensively considers the parameter perturbations such as dimensional error, shape error and mating length caused by machining errors in the machining process of the hydraulic sliding valve, and provides a geometric basis for the subsequent performance prediction of the hydraulic sliding valve.

[0091] Step 2: constructing a hydraulic slide valve entity model based on the hydraulic slide valve non-ideal surface. Specifically, step 2 of the embodiment of the present invention includes: based on the constructed hydraulic slide valve non-ideal surface, digitally reconstructing the entity of the hydraulic slide valve to obtain a hydraulic slide valve entity model.

[0092] Step 3: Extracting hydraulic leakage channels from the hydraulic slide valve entity model. Specifically, step 3 of the embodiment of the present invention includes: performing Boolean operations on the hydraulic slide valve entity model to extract non-ideal geometric channels for oil leakage; and processing the extracted non-ideal geometric channels.

[0093] Among them, the non-ideal geometric flow path of oil leakage is extracted by Boolean operation on the hydraulic slide valve solid model, including:

[0094] Pre-process the geometry of the hydraulic spool valve solid model, perform Boolean subtraction on the hydraulic spool valve solid model in 3D CAD software, extract the non-ideal geometric flow path of oil leakage, and name all boundaries of the flow path entity in the hydraulic spool valve solid model in SCDM and convert the format;

[0095] For the mesh pre-processing of the hydraulic slide valve solid model, select the watertight workflow in Fluent Meshing to mesh the hydraulic slide valve solid model.

[0096] Step 4: Perform oil leakage analysis on the hydraulic leakage channel to obtain a hydraulic slide valve leakage prediction result. Specifically, step 4 of the embodiment of the present invention includes: performing oil leakage analysis on the hydraulic leakage channel based on Fluent to obtain a hydraulic slide valve leakage prediction result.

[0097] See also Figures 2 to 7 In a specific application, an embodiment of the present invention provides a method for predicting leakage of a hydraulic slide valve taking into account non-ideal surface factors, comprising the following steps:

[0098] Step 1: Extract dimension information and tolerance information from the design drawings of the precision hydraulic slide valve, including valve core diameter, fitting length, dimension tolerance, and cylindricity tolerance. The results are 10 mm, 20 mm, 0.005 mm, and 0.004 mm respectively.

[0099] Step 2: Select the basis function correction term corresponding to the cone error, and determine the correction coefficient to be 0.001 based on the tolerance information. Generate a discretized point cloud model of the actual cylinder surface in MATLAB as follows: Figure 2 As shown;

[0100] Step 3: Import the above discretized point cloud model into 3D CAD software, and realize the construction of the non-ideal surface of the cylinder and the digital expression of the physical entity of the precision hydraulic slide valve according to the reverse modeling principle of "point-line-surface-body", such as Figure 3 As shown;

[0101] Step 4: Perform Boolean operations on the matching entities of the precision hydraulic slide valve to extract the non-ideal geometric flow path of oil leakage in the zero position state, and perform simulation pre-processing on the non-ideal geometric flow path, such as Figure 4 As shown;

[0102] Step 5: Perform internal leakage simulation analysis on the precision hydraulic slide valve considering the conical error surface in Fluent. The simulation environment is set as follows: viscosity model "k-epsilon—Realizable—standard wall function (RWF)"; oil density is 900kg / m 3 ; The fluid temperature is 20℃; The oil viscosity at this temperature is 0.0245kg / (m*s); The specified pressure inlet is 2Mpa, and the pressure outlet is 0Mpa; Under this condition, the predicted internal leakage of the precision hydraulic slide valve is 9.313×10 -8 m 3 / s.

[0103] Step 6: Based on the above simulation process, the zero-position internal leakage simulation analysis is performed on the precision hydraulic slide valve considering five different shape error surfaces (including cone, hourglass, barrel, banana and petal shapes). The results are as follows: Figure 5 As shown, from Figure 5 It can be seen that the internal leakage of the hourglass-shaped error surface is the smallest, and the internal leakage of the barrel-shaped error surface is the largest;

[0104] Step 7: By adjusting the parameters of the non-ideal geometric model and the simulation environment, the effects of the dimensional tolerance, cylindrical tolerance, matching length of the valve core and valve sleeve, the pressure difference on both sides of the slide valve, and the fluid temperature on the zero-position internal leakage of the precision hydraulic slide valve are analyzed when the cylinder is in the shape of an hourglass. The results are shown in the figure. Figure 6 As shown, from Figure 6 It can be seen that the fitting length is negatively correlated with the zero-position internal leakage of the precision hydraulic slide valve, and the other factors are positively correlated with the zero-position internal leakage of the precision slide valve.

[0105] The embodiment of the present invention simulates the influence of various factors such as the dimensional tolerance, cylindricity tolerance, fitting length of the valve core and the valve sleeve, the pressure difference on both sides of the sliding valve and the fluid temperature on the zero-position internal leakage of the hydraulic sliding valve, and obtains the influence relationship between each factor and the zero-position internal leakage of the hydraulic sliding valve, providing a reference for improving the processing quality of the precision sliding valve.

[0106] The series of detailed descriptions listed above are only specific descriptions of feasible implementation methods of the present invention. They are not intended to limit the scope of protection of the present invention. Any equivalent implementation methods or changes that do not deviate from the technical spirit of the present invention should be included in the scope of protection of the present invention.

[0107] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0108] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for predicting leakage of a hydraulic slide valve taking into account non-ideal surface factors, characterized in that: The following steps are involved: Step 1: extract data from the hydraulic slide valve design drawing to reconstruct the non-ideal surface of the hydraulic slide valve; Step 2: constructing a hydraulic slide valve entity model based on the non-ideal surface of the hydraulic slide valve; Step 3, extracting the hydraulic leakage flow channel from the hydraulic slide valve physical model; Step 4: performing oil leakage analysis on the hydraulic leakage flow channel to obtain a hydraulic slide valve leakage prediction result; The step one comprises: Extracting the dimension information and tolerance information of the valve core and the valve sleeve in the hydraulic slide valve from the design drawing of the hydraulic slide valve; Determine the coefficient matrix of the correction function in the Chebyshev / Fourier model as the non-ideal surface according to the extracted tolerance information of the valve core and the valve sleeve; The discretized point cloud model of the non-ideal surface is generated by combining the size information of the valve core and the valve sleeve; Reverse modeling of the discretized point cloud model to obtain a reconstruction of the non-ideal surface of the hydraulic slide valve; The method of determining the coefficient matrix of the correction function in the Chebyshev / Fourier model as the non-ideal surface according to the extracted tolerance information of the valve core and the valve sleeve includes: Decomposition of topographic error of non-ideal surface of hydraulic slide valve; Analyze the actual curved surfaces of valve core and valve sleeve based on Chebyshev / Fourier model; Acquire small change data on the size, position and direction of the cylinder corresponding to the valve core and the valve sleeve according to the actual curved surface; Adjust the correction coefficients corresponding to the correction functions of different cylinders based on the slight change data to obtain a coefficient matrix; The method of determining the coefficient matrix of the correction function in the Chebyshev / Fourier model as the non-ideal surface according to the extracted tolerance information of the valve core and the valve sleeve includes: Step (1) uses formula (1) to decompose the topographic error of the non-ideal surface of the precision slide valve; In formula (1), W is the reconstructed surface; G is the basis function matrix; A is the coefficient matrix; f is the basis function; a is the coefficient; In step (2), the Chebyshev / Fourier model is used as the basis function set of the basis function matrix. Under the Chebyshev / Fourier model, the surface morphology of the cylinder corresponding to the actual valve core and the valve sleeve is expressed as: In formula (2), r is the mathematical model of the actual cylinder surface morphology; z is the z-axis coordinate of the actual cylinder; θ is the angular coordinate of the actual cylinder; R is the nominal radius of the ideal cylinder, and the deviation between R and r is required to be much smaller than R; is the second kind Chebyshev polynomial of order i; a ij is the deviation coefficient of an actual cylinder; j is the jth order; b ij is the deviation coefficient of another actual cylinder; Step (3) Optimize formula (2) to obtain formula (3): r(z,θ) = R + F c (z,θ) a formula (3) In formula (3), F c (z,θ) is the row vector of the function of z and θ multiplied by the column vector of coefficients a; the elements of F are T i and cos(jθ) or sin(jθ) individually; where T i Right now is the second-order Chebyshev polynomial of order i; cos(jθ) is the Fourier harmonic cosine component in the Chebyshev / Fourier model; sin(jθ) is the Fourier harmonic sine component; F c (z,θ) is expressed as: In formula (4), is the normalized z coordinate value, ζ is used as the parameter of T, T represents the second kind of Chebyshev polynomial; five functions represent small changes in the size, position and direction of the cylinder, among which: In formula (4), function T0cos(0×θ) is a constant 1, and the coefficient of function T0cos(0×θ) represents the deviation between the radius of the actual cylinder and the radius of the ideal cylinder; in formula (4), function T0cos(θ)=cos(θ), and the coefficient of function T0cos(θ) represents the small displacement of the cylinder in the x direction; in formula (4), function T0sin(θ)=sin(θ), and the coefficient of function T0sin(θ) represents the small displacement of the cylinder in the y direction; if the cylinder is tilted around its center, the coefficient of function T1cos(θ) represents the displacement of the top of the cylinder in the +x direction and the bottom in the -x direction simultaneously; the coefficient of function T1sin(θ) represents the displacement of the top of the cylinder in the +y direction and the bottom in the -y direction simultaneously; T1 represents a 1st-order Chebyshev polynomial; T0 represents a 0th-order Chebyshev polynomial; Step (4): The five functions in step (3) correspond to five different cylinders, and the correction items corresponding to the five different cylinders are: T1(ζ) corresponds to a cone; |T2(ζ)| corresponds to an hourglass shape; -|T2(ζ)| corresponds to a barrel shape; T2(ζ)cos(θ), T2(ζ)sin(θ) correspond to banana shape; T0(ζ)cos(nθ), T0(ζ)sin(nθ) correspond to petal shape; the coefficients corresponding to different correction terms are adjusted to obtain the coefficient matrix of the correction function to control the degree of deviation of different cylinder forms, where T1 represents the 1st-order Chebyshev polynomial; T2 represents the 2nd-order Chebyshev polynomial; T0 represents the 0th-order Chebyshev polynomial; θ represents the angular coordinate of the actual cylinder; nθ represents the product of the number of petals n of the petal-shaped cylinder deviation and the angular coordinate θ of the actual cylinder.

2. A method for predicting hydraulic slide valve leakage considering non-ideal surface factors according to claim 1, characterized in that: The inverse modeling of the discretized point cloud model to obtain the reconstruction of the non-ideal surface of the hydraulic slide valve includes: Importing the point cloud data in the discretized point cloud model into three-dimensional CAD software; According to the reverse modeling principle of "point-line-surface", section curves and multi-section surfaces are generated in sequence in the three-dimensional CAD software to complete the construction of the non-ideal surface of the hydraulic slide valve.

3. The method for predicting hydraulic slide valve leakage considering non-ideal surface factors according to claim 1, characterized in that: The second step comprises: Based on the constructed non-ideal surface of the hydraulic slide valve, the entity of the hydraulic slide valve is digitally reconstructed to obtain a hydraulic slide valve entity model.

4. A method for predicting hydraulic slide valve leakage considering non-ideal surface factors according to claim 1, characterized in that: The step three comprises: Performing Boolean operation on the hydraulic slide valve entity model to extract non-ideal geometric flow channels for oil leakage; The extracted non-ideal geometric flow channel is processed.

5. A method for predicting hydraulic slide valve leakage considering non-ideal surface factors according to claim 4, characterized in that: The method of performing Boolean operation on the hydraulic slide valve entity model to extract the non-ideal geometric flow path of oil leakage includes: Pre-processing the geometry of the hydraulic slide valve entity model, performing Boolean subtraction operation on the hydraulic slide valve entity model in 3D CAD software, extracting non-ideal geometric flow channels of oil leakage, and naming and converting the formats of all boundaries of the flow channel entities in the hydraulic slide valve entity model in SCDM; The mesh of the hydraulic slide valve entity model is pre-processed by selecting the watertight workflow in Fluent Meshing to mesh the hydraulic slide valve entity model.

6. The method for predicting hydraulic slide valve leakage considering non-ideal surface factors according to claim 1, characterized in that: The fourth step comprises: The hydraulic leakage channel is subjected to oil leakage analysis based on Fluent to obtain a hydraulic slide valve leakage prediction result.

Images