Simulation calculation method for sealing pressure resistance value of magnetic liquid sealing device

Abstract

The invention discloses a sealing pressure-resistant value simulation calculation method for a magnetic liquid sealing device, which is applied to the field of sealing pressure-resistant value calculation and comprises the following steps: defining a path from one side to the other side of a seal as a path, mapping the magnetic flux density at a contact gap to the path, obtaining the magnetic flux density of a sampling point, and obtaining a local maximum value and a local minimum value; marking the minimum values before the first local maximum value and after the last maximum value to be invalid, and marking the local minimum values between the first num and the last num of the remaining minimum values and the local maximum values between the first num and the last num of the remaining minimum values to be invalid; num is the number of teeth on one side; respectively acquiring minimum values in a specific range by taking the position of the (num-1) th minimum value on the left side and the position of the (num) th minimum value on the right side as a reference, and respectively marking local minimum values of the first point and the last point which are equal to each other to be valid; and obtaining the sum of the difference values of the local maximum value and the local minimum value, and calculating a sealing pressure resistance value. According to the invention, the workload of calculating the sealing pressure resistance value is reduced.

Description

Technical Field

[0001] The present invention relates to the field of sealing pressure resistance value calculation, and in particular to a sealing pressure resistance value simulation calculation method for a magnetic liquid sealing device. Background Art

[0002] The existing magnetic liquid sealing theory is based on the mass conservation equation, momentum conservation equation, and Bernoulli equation of magnetic liquid, and derives the magnetic liquid sealing pressure formula. Generally, magnetic liquid adopts multi-stage sealing, and its total pressure resistance is the sum of the pressure of each single pole:

[0003]

[0004] Where, Δp is the seal pressure resistance value; N is the seal level (total number of teeth); M s is the saturation magnetization of the magnetic liquid (KA / m); is the maximum magnetic flux density of the i-th sealing level; is the minimum magnetic flux density of the i-th sealing level.

[0005] Therefore, in order to calculate the total withstand voltage, it is necessary to find the maximum magnetic flux density at the top of each pole tooth. and the minimum magnetic flux density at the pole tooth slot And the difference between the two ΔB i , for ΔB i Substitute the sum into the above magnetic liquid seal pressure resistance formula.

[0006] Calculate ΔB i There are usually two methods: The first method is to use the mouse to select the maximum flux density and minimum flux density on each pole tooth in the Maxwell software, record and calculate ΔB i However, this method is very labor-intensive and the selected points are not accurate. The second method is to find the maximum and minimum values ​​of the magnetic flux density in a certain area through programming. Set a path at each pole tooth and tooth slot. The number of paths corresponds to the number of pole teeth. In the Maxwell-Field-Calculator operation path, select the input variable as B. i , select one of the set paths, output the maximum and minimum magnetic flux density values, and calculate the difference between the maximum and minimum values. This method is cumbersome and requires parameterization and program settings for each tooth and slot path. When the number of teeth changes, additional paths and settings are required, which wastes time and resources.

[0007] Therefore, how to provide a method for simulating and calculating the sealing pressure resistance value of a magnetic liquid sealing device that is easy to operate, has a small workload, and has relatively accurate point selection is an urgent problem that needs to be solved by those skilled in the art. Summary of the Invention

[0008] In view of this, the present invention proposes a simulation calculation method for the sealing pressure resistance value of a magnetic liquid sealing device.

[0009] In order to achieve the above object, the present invention adopts the following technical solutions:

[0010] A method for simulating and calculating the sealing pressure resistance value of a magnetic liquid sealing device, comprising:

[0011] Step 1: Define a path with one side of the magnetic liquid seal as the path starting point and the other side as the path end point, select a preset number of sampling points, map the magnetic flux density at the contact gap to the defined path, and obtain the magnetic flux density at each sampling point;

[0012] Step 2: Obtain the local maximum and local minimum values ​​of the magnetic flux density respectively, and ensure that the distance between the local maxima and the distance between the local minima are less than b; where b is the tooth width;

[0013] Step 3: Mark the local minima before the first local maximum and after the last local maximum as invalid, and mark the local minima between the first num and last num of the remaining local minima as invalid, and mark the local maxima between the first num and last num local maxima as invalid; where num is the number of teeth on one side;

[0014] Step 4: Obtain the minimum value within a specific range based on the position of the num-1th local minimum value on the left, and mark the first point equal to the minimum value as a valid local minimum value; obtain the minimum value within a specific range based on the position of the numth local minimum value on the right, and mark the last point equal to the minimum value as a valid local minimum value; where the specific range is (x, x+c), x is the reference position, c = a+1.5b, and a is the tooth width;

[0015] Step 5: Obtain the sum of the differences between the local maximum and the local minimum, and calculate the sealing withstand voltage value in combination with the saturation magnetization.

[0016] As can be seen from the above technical solution, compared with the prior art, the present invention proposes a method for simulating and calculating the sealing pressure resistance value of a magnetic liquid sealing device. Using Maxwell software, a path is defined with one side of the magnetic liquid seal as the path starting point and the other side as the path endpoint. A preset number of sampling points are selected, and the magnetic flux density at the contact gap is mapped onto the defined path to obtain the magnetic flux density at each sampling point. Furthermore, the points and values ​​of the maximum magnetic flux density at the tooth top and the minimum magnetic flux density at the tooth groove of each pole tooth are automatically obtained using Matlab software code. The sum of the difference between the maximum and minimum magnetic flux densities and the sealing pressure resistance value can be directly calculated. This method is not only simple to operate but also saves a lot of workload, achieving a relatively accurate simulation calculation of the sealing pressure resistance value of the magnetic liquid sealing device. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0018] Figure 1 Schematic diagram of the method of the present invention.

[0019] Figure 2 Schematic diagram of the simulation model of the present invention.

[0020] Figure 3 Schematic diagram of the magnetic flux density path of the present invention.

[0021] Figure 4 Schematic diagram of the maximum point of magnetic flux density of the present invention.

[0022] Figure 5 It is a schematic diagram of the Matlab output results of the present invention. DETAILED DESCRIPTION

[0023] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0024] Example 1:

[0025] Example 1 of the present invention discloses a method for simulating and calculating the sealing pressure resistance value of a magnetic liquid sealing device, such as Figure 1 Shown, including:

[0026] Step 1: Define a path with one side of the magnetic liquid seal as the path starting point and the other side as the path end point, select a preset number of sampling points, map the magnetic flux density at the contact gap to the defined path, and obtain the magnetic flux density at each sampling point.

[0027] Step 1 of the present invention is implemented by Maxwell software. Regarding the preset number of sampling points, the more sampling points there are, the more accurate the calculation result is, and the obtained maximum magnetic flux density is closer to the actual maximum magnetic flux density. However, as the amount of calculation increases, the calculation speed decreases.

[0028] Step 2: Obtain the local maximum and local minimum values ​​of the magnetic flux density respectively, and ensure that the distance between the local maxima and the distance between the local minima are less than b, where b is the tooth width.

[0029] Step 3: Mark the local minima before the first local maximum and after the last local maximum as invalid, and mark the local minima between the first num and last num of the remaining local minima as invalid, and mark the local maxima between the first num and last num local maxima as invalid; where num is the number of teeth on one side.

[0030] Step 4: Obtain the minimum value within a specific range based on the position of the num-1th local minimum value on the left side, and mark the first point equal to the minimum value as a valid local minimum value; obtain the minimum value within a specific range based on the position of the numth local minimum value on the right side, and mark the last point equal to the minimum value as a valid local minimum value; where the specific range is (x, x+c), x is the reference position, c=a+1.5b, and a is the tooth width.

[0031] Step 5: Obtain the sum of the differences between the local maximum and the local minimum, and calculate the sealing withstand voltage value in combination with the saturation magnetization.

[0032] Steps 2-5 of the present invention are implemented by Matlab software code.

[0033] Example 2:

[0034] Embodiment 2 of the present invention discloses a specific application of a method for simulating and calculating the sealing pressure resistance value of a magnetic liquid sealing device, as follows:

[0035] Take a single-sided 16-tooth magnetic liquid seal as an example. First, the finite element simulation model is simplified as follows: converting the three-dimensional axisymmetric model into a two-dimensional model; uniformly magnetizing the permanent magnet and uniformly distributing the magnetic permeability of other materials; ignoring model errors; and performing parametric modeling, material and boundary settings, meshing, and analysis settings. Figure 2The model parameterization settings are shown in Table 1.

[0036] Table 1 Model parameter settings

[0037]

[0038] The path analysis was performed by defining a path at the sealing gap using the Maxwell software in step 1 of the above embodiment 1. The path starting point was the side close to the oil storage tank of the cone drill bit, and the path ending point was the side close to the end face of the cone. 3000 sampling points were selected, and the magnetic flux density at the contact gap was mapped to the defined path to obtain the magnetic flux density at each sampling point, as shown in FIG. Figure 3 shown.

[0039] from Figure 3 In the figure, it can be seen that the magnetic flux density fluctuates along the pole teeth and tooth slots. The maximum magnetic flux density is obtained at the pole tooth top and the minimum magnetic flux density is obtained at the tooth slot. The maximum and minimum values ​​appear alternately to form a magnetic field gradient. The maximum values ​​of the magnetic flux density of different pole teeth are different, while the minimum values ​​are relatively close. Therefore, the magnetic field gradient of each pole tooth is different, and the withstand voltage value is different. The position of the permanent magnet is far away from the sealed contact gap. The magnetic flux density at the location of the permanent magnet on the path decays rapidly. Figure 3 A clear valley is formed in the middle position.

[0040] The Matlab software code is used to implement steps 2-5 in Example 1 as follows:

[0041] % Clear all variables in the MATLAB workspace;

[0042] clear variables;

[0043] %Use xlsread to read the data in the Excel file, x is the first column of data, y is the second column of data;

[0044] Table=xlsread("C:\Users\Administrator\Desktop\010.xlsx");

[0045] x=Table(:,1);

[0046] y=Table(:,2);

[0047] % plot data;

[0048] plot(x,y);

[0049] a=0.1%%tooth width;

[0050] num=16%%number of teeth;

[0051] b=0.3%% slot width;

[0052] c=a+1.5*b% the distance from the last minimum value;

[0053] %Find the local maximum, the MinSeparation parameter ensures that the minimum distance between the maximum and minimum is b;

[0054] TF_max=islocalmax(y,'MinSeparation',b,'SamplePoints',x);

[0055] %Find the local minimum, the MinSeparation parameter ensures that the minimum distance between the maximum and minimum is b;

[0056] TF_min=islocalmin(y,'MinSeparation',b,'SamplePoints',x);

[0057] %Draw local maxima and mark them with red inverted triangles;

[0058] plot(x,y,x(TF_max),y(TF_max),'rv');

[0059] hold on;

[0060] %% Delete some local minima;

[0061] % Find the positions of the first and last local maxima;

[0062] loc_left=find(TF_max,1,"first");

[0063] loc_right=find(TF_max,1,"last");

[0064] %Mark the minimum values ​​before the first maximum value and after the last maximum value as invalid, and set the corresponding positions of the local minimum values ​​to 0;

[0065] TF_min(1:loc_left)=0;

[0066] TF_min(loc_right:end)=0;

[0067] % Find the minimum value of the specified number (2num);

[0068] % Find the positions of the first num and last num minimum values;

[0069] loc_mid_left=find(TF_min,num,"first");

[0070] loc_mid_right=find(TF_min,num,"last");

[0071] % The local minimum in the middle is set to invalid;

[0072] TF_min(loc_mid_left(num):loc_mid_right(1))=0;

[0073] % Find the maximum value of the specified number (2num);

[0074] % Find the positions of the first num and last num maximum values;

[0075] loc_max_left=find(TF_max,num,"first");

[0076] loc_max_right=find(TF_max,num,"last");

[0077] % The local maximum in the middle is set to invalid;

[0078] TF_min(loc_mid_left(num):loc_mid_right(1))=0;

[0079] %Calculate the last minimum value on the left;

[0080] % Calculate the reference position of the last minimum value on the left;

[0081] left_last_x=x(loc_mid_left(num-1));

[0082] % Find the minimum y value in a specific range of x (left_last_x to left_last_x+c);

[0083] aa=find((x>left_last_x)&(x <left_last_x+c));

[0084] left_last_min=min(y(aa(1:end)));

[0085] m=find(y==left_last_min);

[0086] %Mark the minimum value as valid (the corresponding position of TF_min is set to 1);

[0087] TF_min(m)=1;

[0088] %Calculate the last minimum value on the right;

[0089] % Calculate the reference position of the last minimum value on the right;

[0090] right_last_x=x(loc_mid_right(num));

[0091] % Find the minimum y value within a specific range of x (right_last_x to right_last_x+c);

[0092] bb=find((x>right_last_x)&(x <right_last_x+c));

[0093] right_last_min=min(y(bb(1:end)));

[0094] n=find(y==right_last_min);

[0095] %Mark the minimum value as valid (the corresponding position of TF_min is set to 1);

[0096] TF_min(n)=1;

[0097] % The valid minimum value is marked with a red upper triangle in the figure;

[0098] plot(x(TF_min),y(TF_min),'r^');

[0099] ylim([0,1.28*pi]);

[0100] % Calculate the sum of the differences between the local maximum and minimum values ​​SUM;

[0101] SUM=sum(y(TF_max)-y(TF_min));

[0102] M = 26.59;

[0103] P=M*SUM / 1000.

[0104] Mark the final effective local maximum and local minimum (the coordinates of the maximum points at the tooth top and tooth groove), such as Figure 4As shown in the figure, the sum of the differences between the local maximum and the local minimum is 65.6594T, and combined with the known saturation magnetization of 26.59KA / m of fluoroether oil-based magnetic fluid, the sealing pressure resistance value is calculated to be 1.7459MPa. Matlab output results are as follows: Figure 5 shown.

[0105] An embodiment of the present invention discloses a method for simulating and calculating the seal withstand voltage of a magnetic liquid seal device. Using Maxwell software, a path is defined with one side of the magnetic liquid seal as the path starting point and the other side as the path endpoint. A preset number of sampling points are selected, and the magnetic flux density at the contact gap is mapped onto the defined path to obtain the magnetic flux density at each sampling point. Furthermore, using Matlab software code, the locations and values ​​of the maximum magnetic flux density at the tooth top and the minimum magnetic flux density at the tooth groove are automatically obtained. The sum of the differences between the maximum and minimum magnetic flux densities, as well as the seal withstand voltage, can be directly calculated. This method is not only simple to operate but also saves a significant amount of work, achieving a relatively accurate simulation calculation of the seal withstand voltage of the magnetic liquid seal device.

[0106] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Reference can be made to the common and similar parts between the various embodiments. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the method description.

[0107] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for simulating and calculating the sealing pressure resistance value of a magnetic liquid sealing device, characterized in that: include: Step 1: Define a path with one side of the magnetic liquid seal as the path starting point and the other side as the path end point, select a preset number of sampling points, map the magnetic flux density at the contact gap to the defined path, and obtain the magnetic flux density at each sampling point; Step 2: Obtain the local maximum and local minimum of the magnetic flux density respectively, and ensure that the distance between the local maxima and the distance between the local minima are less than b; wherein b is the tooth width; Step 3: Mark the local minimum values ​​before the first local maximum value and after the last local maximum value as invalid, and mark the local minimum values ​​between the first num and the last num local maximum values ​​of the remaining local minimum values ​​as invalid, and mark the local maximum values ​​between the first num and the last num local maximum values ​​as invalid; where num is the number of teeth on a single side; Step 4: Obtain the minimum value within a specific range based on the position of the num-1th local minimum value on the left side, and mark the first point equal to the minimum value as a valid local minimum value; obtain the minimum value within a specific range based on the position of the numth local minimum value on the right side, and mark the last point equal to the minimum value as a valid local minimum value; wherein the specific range is (x, x+c), x is the reference position, c=a+1.5b, and a is the tooth width; Step 5: Obtain the sum of the differences between the local maximum and the local minimum, and calculate the sealing withstand voltage value in combination with the saturation magnetization.

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