Balanced vane pump stator inner curve design method

Abstract

The invention discloses a balanced vane pump stator inner curve design method. The method comprises the steps that S1, an inner curve outline of a sample piece stator is obtained; s2, preliminarily estimating a lift angle of a sample stator; s3, checking stator displacement; s4, polar coordinate data of a set number of points on the inner curve contour of the stator are obtained; s5, converting the polar coordinate data of the set number points into rectangular coordinates; s6, copying the rectangular coordinate data value to the first file; s7, opening the first file by adopting three-dimensional software; s8, after a curve is generated in the three-dimensional software, exporting and storing the curve as a second file in a set format; s9, opening the second file, and performing simulation comparison with the inner curve profile of the sample stator; s10, executing the steps S5-S9 again until the generated curve is consistent with the outline of the inner curve of the sample stator; s11, performing stator inner curve trial processing; and S12, checking the profile of the inner curve of the stator subjected to trial processing. According to the balanced vane pump stator inner curve design method, the machining qualification rate of the stator inner curve can be increased.

Description

Technical Field

[0001] The invention belongs to the field of automobile hydraulic power steering oil pump technology, and in particular, relates to a method for designing an inner curve of a balanced vane pump stator. Background Art

[0002] As the power source of the automobile hydraulic power steering system, the balanced vane pump has been used to this day for its significant advantages such as compact structure, uniform flow, high volumetric efficiency, low noise, and stable operation. The shape and properties of the inner surface of the stator, as the core component of the vane pump, determine the movement state of the vane, which has a significant impact on the performance, noise and life of the vane pump.

[0003] like Figure 2 As shown, the inner surface of the stator of the balanced vane pump is approximately elliptical, which is composed of two small arcs, two large arcs and four transition curves. When the rotor rotates, the blades move radially in the rotor grooves and press against the inner surface of the stator under the action of centrifugal force and root pressure oil. Multiple sealed spaces are formed by the blades, the inner surface of the stator, the outer surface of the rotor and the oil distribution plates on both sides. When the rotor rotates in the direction shown in the figure, in the process of the sealed space on the small arc moving from the transition curve to the large arc, the blades extend outward, the volume of the sealed space increases, and the oil is sucked in. In the process of moving from the large arc to the small arc through the transition curve, the blades are gradually pressed into the grooves by the inside of the stator, the volume of the sealed space becomes smaller, and the oil is pressed out from the oil pressure port. Therefore, every time the rotor rotates one circle, each working space must complete two oil suction and oil pressure.

[0004] The existing stator inner curve is manufactured by cam grinding, which means first using the original sample stator profile to make the cam profile, and then grinding the stator inner curve according to the cam profile motion trajectory. The main disadvantages of manufacturing the stator inner curve by this method are as follows:

[0005] a. The cam is ground to produce the inner curve of the stator. It is necessary to first grind the inner curve of all the stators in one shift roughly, and then clamp them again to grind the inner curve finely;

[0006] b. The cam is manufactured by grinding. When the internal curve cam of the stator is in operation, the cam and the machine tool spindle are in line contact, the contact point pressure is high, and it is easy to wear;

[0007] c. The cam is manufactured by grinding the inner curve of the stator, the product stability is poor, and the verticality and roughness of the curve are difficult to control;

[0008] d. The cam is ground against the inner curve of the stator. The product model is single and difficult to modify. One inner curve of the stator must correspond to one cam;

[0009] e. After the cam profile is ground out using the sample, the surface nitriding treatment needs to be outsourced, which takes a long time (about 15 days). Summary of the invention

[0010] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention provides a method for designing the inner curve of a stator of a balanced vane pump, the purpose of which is to improve the processing qualification rate of the inner curve of the stator.

[0011] In order to achieve the above object, the technical solution adopted by the present invention is: a method for designing an inner curve of a stator of a balanced vane pump, comprising the steps of:

[0012] S1. Obtain the inner curve profile of the sample stator as a reference standard;

[0013] S2. Preliminary estimate of the lift angle of the sample stator;

[0014] S3. Measure the design parameters of the sample stator and verify whether the stator displacement meets the design requirements according to the displacement calculation formula;

[0015] S4. According to the obtained design parameters of the sample stator, a curve design tool is used to perform calculations to obtain polar coordinate data of a set number of points on the inner curve profile of the sample stator;

[0016] S5, converting the obtained polar coordinate data of the set number of points into rectangular coordinates;

[0017] S6, creating a new text document, copying the rectangular coordinate data value obtained in step S5 into the text document, and then saving the text document as a first file in a set format;

[0018] S7, using 3D software to open the first file;

[0019] S8. After the curve is generated in the three-dimensional software, it is exported and saved as a second file in a set format;

[0020] S9, opening the second file, and performing a simulation comparison with the inner curve profile of the sample stator obtained in step S1;

[0021] S10, adjusting the lift angle and the curve design coefficient according to the comparison result, recalculating and executing steps S5 to S9 again, until the generated curve is consistent with the inner curve profile of the sample stator;

[0022] S11, importing the polar coordinate data obtained in step S4 into a CNC stator curve grinder to perform trial processing of the stator inner curve;

[0023] S12. Check whether the inner curve profile of the trial-machined stator is consistent with the inner curve profile of the sample stator.

[0024] In step S2, the lift angle is preliminarily estimated based on the oil window angles of the front and rear oil distribution plates and the size of the unloading groove of the sample stator.

[0025] In the step S3, the design parameters of the sample stator include the major diameter and minor diameter data of the sample stator.

[0026] In step S3, the displacement calculation formula is: Among them, R is the long radius of the arc part of the inner surface of the vane pump stator, r is the short radius of the arc part of the inner surface of the vane pump stator, h is the blade height, s is the blade thickness, z is the number of blades, and θ is the blade inclination angle.

[0027] In step S4, the lift angle, the major diameter and the minor diameter data of the sample stator are substituted into the curve design tool for calculation to obtain the polar coordinate data of 361 points.

[0028] In step S5, a new Excel table is created to convert the polar coordinate data of 361 points into rectangular coordinates, and the Z value is all 0.

[0029] In step S7, the three-dimensional software used is UG software.

[0030] In step S8, after the curve is generated, it is exported in the drawing module environment of the UG software and saved in dxf or dwg format.

[0031] The method for designing the inner curve of a balanced vane pump stator also includes the step of: S13, installing the stator with consistent measurement results into the assembly pump, and then conducting a test.

[0032] The method for designing the inner curve of the stator of a balanced vane pump of the present invention has the following beneficial effects:

[0033] 1. The CNC curve grinder manufactures the stator inner curve instead of the cam by grinding the stator inner curve. Since the processing variables of the CNC curve grinder are controllable and have automatic compensation function, the stator inner curve processing qualification rate is high and the consistency is good;

[0034] 2. The CNC curve grinder does not need secondary clamping to manufacture the internal curve of the stator. After the rough grinding of the curve is completed, the workbench moves to the fine grinding area for fine processing of the curve. The time is short and the efficiency is high. The verticality and roughness of the curve can be guaranteed.

[0035] 3. The cam is ground by the stator inner curve product model is single, the contour cannot be modified, especially for some products with the same positioning method, the same minor diameter and different major diameter, only need to modify the curve design parameters through this method to achieve trial processing;

[0036] 4. No more cam grinding, which not only saves the cost of cam use, but also shortens the mass production time. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] This specification includes the following drawings, which show the following contents:

[0038] Figure 1 is the stator internal curve diagram;

[0039] Figure 2 It is a schematic diagram of the inner surface structure of a balanced vane pump stator in the prior art. DETAILED DESCRIPTION

[0040] The specific implementation methods of the present invention are further explained in detail below by describing the embodiments with reference to the accompanying drawings, with the aim of helping those skilled in the art to have a more complete, accurate and in-depth understanding of the concept and technical solution of the present invention and facilitating its implementation.

[0041] The present invention provides a method for designing an inner curve of a stator of a balanced vane pump, comprising the following steps:

[0042] S1. Obtain the inner curve profile of the sample stator as a reference standard;

[0043] S2. Preliminary estimate of the lift angle of the sample stator;

[0044] S3. Measure the design parameters of the sample stator and verify whether the stator displacement meets the design requirements according to the displacement calculation formula;

[0045] S4. According to the obtained design parameters of the sample stator, a curve design tool is used to perform calculations to obtain polar coordinate data of a set number of points on the inner curve profile of the sample stator;

[0046] S5, converting the obtained polar coordinate data of the set number of points into rectangular coordinates;

[0047] S6, creating a new text document, copying the rectangular coordinate data value obtained in step S5 into the text document, and then saving the text document as a first file in a set format;

[0048] S7, using 3D software to open the first file;

[0049] S8. After the curve is generated in the three-dimensional software, it is exported and saved as a second file in a set format;

[0050] S9, opening the second file, and performing a simulation comparison with the inner curve profile of the sample stator obtained in step S1;

[0051] S10, adjusting the lift angle and the curve design coefficient according to the comparison result, recalculating and executing steps S5 to S9 again, until the generated curve is consistent with the inner curve profile of the sample stator;

[0052] S11, importing the polar coordinate data obtained in step S4 into a CNC stator curve grinder to perform trial processing of the stator inner curve;

[0053] S12, checking whether the inner curve profile of the trial-processed stator is consistent with the inner curve profile of the sample stator;

[0054] S13. Install the stator with consistent measurement results into the assembly pump and then conduct the test;

[0055] S14. After the above conditions are met, a small batch test assembly is carried out for verification, and finally the stator curve data is solidified and archived.

[0056] Specifically, the method for designing the internal curve of a stator of a balanced vane pump of the present invention is to calculate the internal curve data of the stator by a self-developed curve design tool and make corrections, and then import the designed data into a CNC curve grinder to process the internal curve of the stator.

[0057] like Figure 1 As shown, the internal curve of the stator of the balanced vane pump is mainly composed of 8 parts, namely, small diameter area, oil suction lift area, large diameter area, oil pressure drop area, small diameter area, oil suction lift area, large diameter area and oil pressure drop area; Figure 1 The lb curve segment and the fh curve segment are small diameter areas, the bc curve segment and the hi curve segment are oil suction lift areas, the ce curve segment and the ik curve segment are large diameter areas, and the ef curve segment and the kl curve segment are oil pressure drop areas;

[0058] A balanced vane pump is also called a double-acting vane pump, that is, each sealed space has two oil suction and oil discharge processes when the rotor rotates one circle, so the internal curve of the stator is arranged in a symmetrical state, that is, the internal curve of the stator in the range of 0°~180° is exactly the same as the range of 180°~360°.

[0059] The stator inner curve minor diameter area of ​​the balanced vane pump is a concentric circle curve. This minor diameter size is one of the important dimensions for calculating the stator displacement and is usually measured directly by a vernier caliper. The bl curve segment and the fh curve segment are symmetrical along the vertical center line, and the ba curve segment, al curve segment, fg curve segment, and gh curve segment are symmetrical along the horizontal center line.

[0060] The oil suction lift area of ​​the stator inner curve of the balanced vane pump is the oil suction area, also known as the low-pressure area. Due to the unbalanced hydraulic force between the top and the root of the blade, the top of the blade acts on the low pressure of the oil suction chamber, while the root acts on the high pressure of the oil pressure chamber. The contact pressure between the top of the blade and the inner surface curve of the stator is relatively large, so that an oil film cannot be formed, which easily causes wear of this section of the stator curve. Therefore, this section of the curve needs to be corrected with the help of the independently developed curve design tool. After modifying the data parameters, the derived curve is simulated and compared with the original curve. The purpose is to ensure that the blade can move smoothly when sliding along the curve, and there is no sudden change in radial velocity, acceleration and acceleration change rate. At the same time, there must be a common tangent with the connection between the large and small diameters.

[0061] The large diameter area of ​​the stator inner curve of the balanced vane pump is a non-circular curve, also known as the pre-compression curve segment. Since one end of this curve acts on the low pressure of the oil suction chamber and the other end acts on the high pressure of the oil discharge chamber, when the sealed working chamber turns from low pressure to high pressure, the high-pressure oil will quickly reverse and flow back to the working chamber, causing a huge hydraulic shock, which has a great impact on the pressure pulsation, noise and wear of the oil pump. Therefore, in order to prevent the occurrence of high-pressure reflux and hydraulic shock, this curve segment is set to a non-circular, decreasing curve segment, such as Figure 1 As shown, the dimensions of the dividing points c and i, which are the oil suction lift zone and the large diameter zone, are the maximum dimensions of the inner surface of the stator. This dimension is also one of the important dimensions for calculating the stator displacement, and is usually directly tested by a vernier caliper. When rotating from point c to point e and from point i to point k, the polar coordinates of the corresponding points gradually become smaller.

[0062] The oil pressure drop zone of the stator inner curve of the balanced vane pump is the oil discharge zone, also known as the high-pressure zone. The contact pressure between the blade and the stator in this curve is very small, and a good pressure oil film can be formed between the two, which is basically in a fluid lubrication state. The contact pressure between the top of the blade and the inner surface curve of the stator is mainly borne by the oil film. There is basically no direct contact friction between metal and metal, and the wear is usually not serious. However, the motion trajectory of this curve has a significant impact on the performance and noise of the vane pump, so this curve also needs to be corrected with the help of curve design tools. After modifying the data parameters, the derived curve is simulated and compared with the original curve. The purpose is to ensure that the blade can move smoothly when sliding along the curve, and there is no sudden change in radial velocity, acceleration and acceleration change rate. At the same time, there must be a common tangent with the connection between the large and small diameters.

[0063] In the above step S2, the sample stator is projected or three-coordinate measured to obtain the inner curve profile of the stator, which is saved in dxf or dwg format as a reference standard.

[0064] In the above step S2, the lift angle is preliminarily estimated based on the oil window angles of the front and rear oil distribution plates and the size of the unloading groove of the sample stator.

[0065] In the above step S3, the design parameters of the sample stator include the major diameter and minor diameter data of the sample stator. The major diameter and minor diameter data of the sample stator are accurately measured, and then the measurement results are substituted into the displacement calculation formula.

[0066] The displacement calculation formula is: Among them, R is the major radius of the arc part of the inner surface of the vane pump stator, r is the minor radius of the arc part of the inner surface of the vane pump stator, h is the blade height, s is the blade thickness, z is the number of blades, θ is the blade inclination angle, and R, r, h, s, z and θ are curve design coefficients.

[0067] In the above step S4, the lift angle, the major diameter and the minor diameter data of the sample stator are substituted into the curve design tool for calculation to obtain the polar coordinate data of 361 points.

[0068] Curve design tool description: After inputting the lift angle, stator major diameter and minor diameter, the polar coordinate values ​​of 361 points are calculated. The processing can be performed by inputting the polar coordinate values ​​of 361 points into the CNC machine tool. The lift angle is obtained (estimated) by projecting the oil window angle of the oil distribution plate. Since the starting angle of the stator internal curve oil suction lift area is uncertain (some products are at the beginning of the oil suction window of the oil distribution plate, and some are one degree in advance), the accurate lift angle can only be determined by comparing the 361 points derived after calculation with the sample.

[0069] The principle of the curve design tool is as follows: set 0 to 361 angles, each angle corresponds to a point polar coordinate. In the small diameter area, the polar coordinate of the point is equal to half of the small diameter. In the suction lift area and the pressure drop area, set the variable coefficient, calculate the sum and difference of the result and the small diameter through formula (1), modify the variable coefficient value, so that the corresponding polar coordinate value ρ changes; in the large diameter area, measure the size change value of the large arc part of the stator, calculate the difference between the result and the large diameter through formula (2), and obtain the corresponding polar coordinate value g; then use the angle to radian formula to obtain the corresponding X and Y values ​​of the 361 points, select 0 for the Z value, and finally copy the X, Y, and Z values ​​of the 361 points into the UG software to generate the curve.

[0070]

[0071] Among them, R is the long radius of the arc part of the inner surface of the vane pump stator, r is the short radius of the arc part of the inner surface of the vane pump stator, θ is the transition curve angle, and α is the lift angle.

[0072]

[0073] Among them, d is the change difference of the large diameter part of the stator inner curve, a is the decreasing angle, and β is the decreasing curve angle.

[0074] In the above step S5, a new Excel table is created to convert the polar coordinate data of 361 points into rectangular coordinates (X, Y, Z values), and the Z value is 0.

[0075] In the above step S6, a new text document is created, a total of 361 data values ​​of rectangular coordinates (X, Y, Z values) are copied into the text document, the text document is saved as the first file, and the suffix of the first file is changed to .dat.

[0076] In the above step S7, the three-dimensional software used is UG software (Unigraphics NX). Open the UG software, in the new model environment, click the Insert Spline command, pass the point, the point in the file, and select the first file saved previously.

[0077] In the above step S8, after the curve is generated, it is exported in the drawing module environment of the UG software and saved in the dxf or dwg format to form a second file.

[0078] In the above step S9, the second file is opened in the CAD software and simulated and compared with the sample stator profile obtained in step S1.

[0079] In the above step S10, according to the comparison result, the lift angle, curve design coefficient and other data are adjusted, and steps S5 to S9 are repeated after recalculation until the lift curve is highly consistent with the original sample curve.

[0080] In the above step S11, the 361-point polar coordinate data generated in step S4 are imported into the CNC stator curve grinder to perform trial machining of the stator inner curve.

[0081] In the above step S12, the three-coordinate measurement is performed on the trial-processed stator to check whether the inner curve profile of the stator is consistent with the inner curve profile of the standard sample.

[0082] In the above step S13, the stator with consistent measurement results is installed in the assembly pump to test the performance, noise and inner surface wear.

[0083] The present invention is described above by way of example in conjunction with the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-mentioned methods. As long as various non-substantial improvements are made using the method concept and technical solution of the present invention; or the above concept and technical solution of the present invention are directly applied to other occasions without improvement, they are all within the protection scope of the present invention.

Claims

1. A method for designing the inner curve of a balanced vane pump stator, characterized in that: Includes steps: S1. Obtain the inner curve profile of the sample stator as a reference standard; S2. Preliminary estimate of the lift angle of the sample stator; S3. Measure the design parameters of the sample stator and verify whether the stator displacement meets the design requirements according to the displacement calculation formula; S4. According to the obtained design parameters of the sample stator, a curve design tool is used to perform calculations to obtain polar coordinate data of a set number of points on the inner curve profile of the sample stator; S5, converting the obtained polar coordinate data of the set number of points into rectangular coordinates; S6, creating a new text document, copying the rectangular coordinate data value obtained in step S5 into the text document, and then saving the text document as a first file in a set format; S7, using 3D software to open the first file; S8. After the curve is generated in the three-dimensional software, it is exported and saved as a second file in a set format; S9, opening the second file, and performing a simulation comparison with the inner curve profile of the sample stator obtained in step S1; S10, adjusting the lift angle and the curve design coefficient according to the comparison result, recalculating and executing steps S5 to S9 again, until the generated curve is consistent with the inner curve profile of the sample stator; S11, importing the polar coordinate data obtained in step S4 into a CNC stator curve grinder to perform trial processing of the stator inner curve; S12. Check whether the inner curve profile of the trial-machined stator is consistent with the inner curve profile of the sample stator.

2. The method for designing inner curve of a balanced vane pump stator according to claim 1, characterized in that: In step S2, the lift angle is preliminarily estimated based on the oil window angles of the front and rear oil distribution plates and the size of the unloading groove of the sample stator.

3. The method for designing inner curve of a balanced vane pump stator according to claim 1, characterized in that: In the step S3, the design parameters of the sample stator include the major diameter and minor diameter data of the sample stator.

4. The method for designing the inner curve of a balanced vane pump stator according to any one of claims 1 to 3, characterized in that: In step S3, the displacement calculation formula is: Among them, R is the long radius of the arc part of the inner surface of the vane pump stator, r is the short radius of the arc part of the inner surface of the vane pump stator, h is the blade height, s is the blade thickness, z is the number of blades, and θ is the blade inclination angle.

5. The method for designing the inner curve of a balanced vane pump stator according to any one of claims 1 to 3, characterized in that: In step S4, the lift angle, the major diameter and the minor diameter data of the sample stator are substituted into the curve design tool for calculation to obtain the polar coordinate data of 361 points.

6. The method for designing the inner curve of a balanced vane pump stator according to claim 5, characterized in that: In step S5, a new Excel table is created to convert the polar coordinate data of 361 points into rectangular coordinates, and the Z value is all 0.

7. The method for designing the inner curve of a balanced vane pump stator according to any one of claims 1 to 6, characterized in that: In step S7, the three-dimensional software used is UG software.

8. The method for designing inner curve of a balanced vane pump stator according to claim 7, characterized in that: In the step S8, after the curve is generated, it is exported in the drawing module environment of the UG software and saved in the dxf or dwg format.

9. The method for designing the inner curve of a balanced vane pump stator according to any one of claims 1 to 6, characterized in that: Also includes the steps: S13. Install the stator with consistent measurement results into the assembly pump and then conduct the test.

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