Guide vane structure of impeller type vacuum pump and adjusting method of guide vane structure

Abstract

The invention provides a guide vane structure of an impeller type vacuum pump and an adjusting method of the guide vane structure, the guide vane structure comprises a guide vane, a rear cover plate and an impeller, the guide vane is composed of a guide vane disc and a plurality of guide vane blades, and the plurality of guide vane blades are symmetrically arranged on the periphery of the impeller by taking an impeller shaft as a symmetry axis; an annular guide vane groove is formed in the rear cover plate, an arc-shaped adjusting hole is formed in the annular guide vane groove, the shape, the size and the depth of the annular guide vane groove are matched with the shape, the size and the thickness of the guide vane disc, and the guide vane disc is installed in the annular guide vane groove. Threaded holes are formed in the guide vane disc, and the guide vane disc is fixedly connected with the rear cover plate through matching of the threaded holes, the arc-shaped adjusting holes, bolts and nuts. By selecting different fastening positions of the bolts and the nuts on the arc-shaped adjusting holes, the included angle between the guide vane blade and the corresponding radius of the baffle tongue point in the pump body can be adjusted. According to the invention, high-efficiency kinetic energy conversion and flow field rectification of the vacuum pump under complex working conditions can be ensured, and the gas conveying efficiency and the equipment reliability are remarkably improved.

Description

Technical Field

[0001] This invention belongs to the field of vacuum pump technology, and specifically relates to a guide vane structure and adjustment method of an impeller vacuum pump. Background Technology

[0002] The guide vane in the title of this invention refers to a component used in conjunction with the impeller in an impeller-type vacuum pump. Its function is to improve the aerodynamic efficiency and operational stability of the vacuum pump. The so-called guide vane structure refers to the assembly relationship and functional cooperation between the guide vane and components such as the impeller and the back cover plate.

[0003] Improving the aerodynamic efficiency and operational stability of impeller vacuum pumps by incorporating guide vanes has been a research direction in this field in recent years. For example, invention patent application CN118482040A discloses a guide vane (actually a guide vane structure) for a multi-stage centrifugal pump (belonging to the category of impeller vacuum pumps), comprising:

[0004] A cover plate, wherein the cover plate is provided with a through hole;

[0005] Multiple first blades are disposed on the cover plate and arranged around the through hole. A first flow channel is formed between adjacent first blades. The end of the first flow channel facing the through hole is a first inlet, and the end of the first flow channel facing away from the through hole is a first outlet.

[0006] Multiple second blades are disposed on the first blade, and the number of second blades corresponds to the number of first blades. A second flow channel is formed between adjacent second blades. The end of the second flow channel facing the through hole is a second outlet, and the end of the second flow channel facing away from the through hole is a second inlet. The second inlet is disposed corresponding to the first outlet.

[0007] Multiple third blades are provided, with at least two third blades between adjacent second blades. The length of each third blade is less than the length of the second blade, and the height of each third blade is less than the height of the second blade.

[0008] The above technical solution constitutes the basic technical content of the guide vane structure in the invention patent application CN118482040A. The detailed technical content of the guide vane structure can be found in the embodiments described in paragraphs 0065-0102 of the specification.

[0009] For example, the invention patent CN104088798 B discloses a noise-reducing and vibration-damping centrifugal pump (belonging to the category of impeller-type vacuum pumps), which includes a guide vane assembly (essentially disclosing the guide vane structure). The guide vane assembly is fixed between the inner wall of the pump body and the upper end of the column tube, and includes multiple guide vanes symmetrically distributed around the central axis of the impeller shaft. Each guide vane is fixed on a fixed disk, and each guide vane is inclined and divergent, tangent to the edge of the fixed disk. The guide vane outlets are formed by spacing between adjacent guide vanes. Detailed technical content of this guide vane assembly can be found in the embodiments described in paragraphs 0020-0025 of the specification.

[0010] In summary, the technical solutions disclosed in the aforementioned invention patents or patent applications (hereinafter collectively referred to as the prior art) improve the aerodynamic efficiency and operational stability of vacuum pumps by employing corresponding guide vane structures. However, the prior art also has certain technical defects, mainly that the angle of the guide vane (the angle between the guide vane blade and the corresponding radius of the tongue point in the pump body) is not adjustable, making it difficult to ensure the aerodynamic efficiency and operational stability of the vacuum pump under complex and variable operating conditions. Summary of the Invention

[0011] The purpose of this invention is to overcome the technical defects of the prior art, thereby further improving the aerodynamic efficiency and operational stability of impeller vacuum pumps under complex working conditions.

[0012] To achieve the above objectives, the following technical solution is adopted:

[0013] A guide vane structure for an impeller-type vacuum pump includes a guide vane, a rear cover plate, and an impeller. The guide vane consists of a guide vane disk and multiple guide vane blades. The multiple guide vane blades are located on one side of the guide vane disk and are integrally formed with the guide vane disk. The multiple blades are symmetrically arranged around the impeller shaft as the axis of symmetry. An annular guide vane groove is provided on the rear cover plate, and an arc-shaped adjustment hole is provided in the annular guide vane groove. The inner wall of the arc-shaped adjustment hole is hardened. The shape, size, and depth of the annular guide vane groove match the shape, size, and thickness of the guide vane disk, and the guide vane disk is installed in the annular guide vane groove. The guide vane disc is provided with threaded holes, which are connected and fixed to the rear cover plate through the threaded holes, arc-shaped adjustment holes, and bolts and nuts. By selecting different fastening positions of the bolts and nuts on the arc-shaped adjustment holes, the included angle between the guide vane blades and the corresponding radii of the tongue point in the pump body can be adjusted. The central angle α corresponding to the arc-shaped adjustment hole is 360° / m, where m represents the number of guide vane blades. The number of arc-shaped adjustment holes is x, and the x arc-shaped adjustment holes are symmetrically distributed in the annular guide vane groove with the impeller shaft as the axis of symmetry. x is an integer, and 2≤x≤m.

[0014] Based on the above technical solutions, the present invention may employ the following additional technical means to better or more specifically solve the technical problems to be solved by the present invention:

[0015] The number of blades is 5.

[0016] Furthermore, scale markings are provided on the edge of the arc-shaped adjustment hole.

[0017] Furthermore, the bolt is a wing bolt.

[0018] Using the above-mentioned technical solution as the material and technical means, the present invention further provides a method for adjusting the guide vane structure of an impeller vacuum pump (referring to a broad adjustment method, which includes the processing method of the guide vane structure itself), comprising the following steps:

[0019] Step 1: A ring-shaped guide vane groove is formed on the back cover plate. The shape, size, and depth of the ring-shaped guide vane groove match the shape, size, and thickness of the guide vane disk. An arc-shaped adjustment hole is opened in the ring-shaped guide vane groove. The central angle α corresponding to the arc-shaped adjustment hole is 360° / m, where m is the number of guide vane blades, and the number of arc-shaped adjustment holes is x, where x is an integer and 2≤x≤m. The x arc-shaped adjustment holes are symmetrically distributed in the ring-shaped guide vane groove with the impeller shaft as the axis of symmetry.

[0020] Step 2: Calculate the baseline coefficient k1, k1 = α / R z·cosα ;

[0021] In the formula, R is the radius of the guide vane disk, α is the central angle corresponding to the arc-shaped adjustment hole, and z is the exponential coefficient;

[0022] Step 3: Calculate the baseline coefficient k2, k2 = 0.812Qd / P;

[0023] In the formula, Qd is the design flow rate and P is the rated power;

[0024] Step 4: Adjust the optimal angle β, β = k1·n a (T0 / T) b ·k2 c ·η d ;

[0025] In the formula, β is the angle between the guide vane blade and the corresponding radius of the tongue point, n is the vacuum pump speed, T is the actual gas temperature, T0 is the standard operating temperature, η is the vacuum pump efficiency, k1 and k2 are reference coefficients, and a, b, c, and d are exponential coefficients.

[0026] Step 5: First, align the guide vane blade with the tongue. At this point, the angle β between the corresponding radius of the guide vane blade and the tongue is 0°. Then, rotate the guide vane disk clockwise until the angle β between the corresponding radius of the guide vane blade and the tongue is the same as the optimal angle β obtained in Step 4.

[0027] Furthermore, it also includes step 6: adjusting the gap between the impeller and the guide vane blades, controlling the radial gap between them within the range of 0.015-0.03D, where D is the impeller diameter.

[0028] Furthermore, during step 1, the inner wall of the arc-shaped adjustment hole is hardened.

[0029] Compared with the prior art described above, the main beneficial effects of the present invention are as follows:

[0030] The annular guide vane groove formed on the rear cover plate, and the arc-shaped adjustment hole opened in the annular guide vane groove, functionally constitute the angle adjustment mechanism in this invention. By selecting different fastening positions of the bolts and nuts on the arc-shaped adjustment hole, this invention can adjust the included angle between the guide vane blade and the corresponding radius of the tongue point in the pump body, thereby ensuring that the vacuum pump achieves efficient kinetic energy conversion and flow field rectification under complex working conditions, significantly improving the gas delivery efficiency and equipment reliability of the vacuum pump. Attached Figure Description

[0031] Figure 1 This is a top view of the guide vane assembly in one embodiment of the present invention;

[0032] Figure 2 This is a front view (or front view) of the guide vane assembly in this embodiment;

[0033] Figure 3 This is a top view of the rear cover in this embodiment;

[0034] Figure 4 This is a longitudinal section view of the rear cover plate in this embodiment;

[0035] Figure 5 This is a top view of the guide vane in this embodiment;

[0036] Figure 6 This is a cross-sectional view of the guide vane in this embodiment.

[0037] In the picture:

[0038] 1—Guide leaf; 101—Guide leaf blade;

[0039] 102 – Guide vane disc; 103 – Threaded hole;

[0040] 2—Rear cover plate; 201—Annular guide vane groove;

[0041] 202 – Arc-shaped adjustment hole; 203 – O-ring seal;

[0042] 3 - Impeller. Detailed Implementation

[0043] To facilitate a thorough understanding of the technical solution of the present invention by those skilled in the art, an embodiment of the present invention is described below in conjunction with the accompanying drawings.

[0044] like Figures 1 to 6 As shown, a guide vane structure for an impeller-type vacuum pump includes a guide vane 1, a rear cover plate 2, and an impeller 3. The guide vane 1 consists of a guide vane disk 102 and multiple guide vane blades 101. The multiple guide vane blades 101 are located on one side of the guide vane disk 102 and are integrally formed with the guide vane disk 102. The multiple guide vane blades 101 are symmetrically arranged around the impeller 3 with the impeller shaft as the axis of symmetry. An annular guide vane groove 201 is provided on the rear cover plate 2, and an arc-shaped adjustment hole 202 is provided within the annular guide vane groove 201. The shape, size, and depth of the annular guide vane groove 201 match the shape, size, and thickness of the guide vane disk 102, and the guide vane disk 102 is installed within the annular guide vane groove 201. A threaded hole 103 is provided on the guide vane disk, which is connected and fixed to the rear cover plate 2 through the threaded hole 103, the arc-shaped adjustment hole 202, and the engagement of bolts and nuts (existing technology, not shown in the figure). The operator can adjust the angle between the guide vane 101 and the corresponding radius of the tongue-separating point (a non-existent technical feature, not shown in the figure; the tongue-separating point refers to the starting point of the tongue) by selecting different tightening positions of the bolts and nuts on the arc-shaped adjusting hole 202. (The angle between the trailing edge of the guide vane 101 and the tongue of the vacuum pump's volute is at the same radius.) Furthermore, due to the symmetry between the guide vanes 101, the angle between each guide vane 101 and the corresponding radius of the tongue-separating point is the same.

[0045] The central angle α corresponding to the arc-shaped adjustment hole 202 is 360° / m, where m represents the number of guide vane blades 101 (in this embodiment, the value of m is 5). In actual implementation of the technical solution of this invention, the specific value of m can be adjusted according to the pump type and actual needs. For example, but not limited to, the value of m is 4, 5, or 6, that is, the number of guide vane blades 101 is 4, 5, or 6. In addition, multiple arc-shaped adjustment holes 202 can be provided within the annular guide vane groove 201. There is a certain correlation between the number of arc-shaped adjustment holes 202 and the number of blades. Specifically, the number of arc-shaped adjustment holes 202 is x, where x is an integer, and 2≤x≤m. x arc-shaped adjustment holes 202 are symmetrically distributed within the annular guide vane groove 201 with the impeller shaft as the axis of symmetry.

[0046] To facilitate operators in intuitively reading the adjustment angle value, this embodiment sets a scale mark (not shown in the figure) on the edge of the arc-shaped adjustment hole 202, and the scale mark accuracy can reach 1°.

[0047] To facilitate easy tightening and loosening of the bolts by operators, wing bolts are preferred in this embodiment.

[0048] To enhance the sealing performance of the rear cover plate 2, an O-ring 203 is provided on the inner edge of the rear cover plate 2 in this embodiment.

[0049] To reduce wear on the inner wall of the arc-shaped adjustment hole 202 during the rotation of the guide vane disk 102, this embodiment performs a hardening treatment on the inner wall of the arc-shaped adjustment hole 202. The process requirements for hardening the inner wall of the arc-shaped adjustment hole 202 (hereinafter referred to as the workpiece) are as follows:

[0050] S1. Clean the workpiece to remove surface oil, rust, etc., and ensure that the workpiece is heated evenly.

[0051] S2, Heating: Place the workpiece in a heating furnace, heat it, and then keep it at that temperature for a period of time to allow the internal structure of the workpiece to be uniformly transformed into austenite.

[0052] S3, Cooling: The heated workpiece is quickly placed in a cooling medium for rapid cooling, so that the austenite does not have time to decompose and is transformed into martensite, thereby achieving hardening.

[0053] S4, Post-processing: Some workpieces (such as those that are brittle due to the material) need to be tempered at low temperature (150-250℃) in order to eliminate internal stress, thereby improving their brittleness while retaining high hardness.

[0054] The structural features of one embodiment of the present invention have been described above with reference to the accompanying drawings. The following further describes its adjustment method (referring to a broad adjustment method that encompasses the processing method of the guide vane structure itself), including the following steps:

[0055] Step 1: A ring-shaped guide vane groove 201 is machined on the rear cover plate 2. The shape, size, and depth of the ring-shaped guide vane groove 201 match the shape, size, and thickness of the guide vane disk 102 (strict matching is required to ensure that the guide vane disk 102 can rotate smoothly within the ring-shaped guide vane groove 201 while avoiding abrupt changes in the flow area caused by the mismatch between the groove depth and the disk thickness—the abrupt change should be ≤1%, thereby preventing the generation of local eddies). Arc-shaped adjustment holes 202 are formed within the ring-shaped guide vane groove 201. The angle α corresponding to the central angle of the arc-shaped adjustment hole 202 is 360° / m, where m is the number of blades; the number of arc-shaped adjustment holes is x, where x is an integer, and 2≤x≤m. x arc-shaped adjustment holes 202 are symmetrically distributed within the ring-shaped guide vane groove 201 with the impeller shaft as the axis of symmetry. It should also be noted that, functionally, the annular guide vane groove 201 and the arc-shaped adjustment hole 202 essentially constitute the angle adjustment mechanism in this invention. Therefore, after step 1 is executed, the adjustable range of the guide vane blade 101 is already determined.

[0056] Step 2: Calculate the baseline coefficient k1, k1 = α / R z·cosα ;

[0057] In the formula, R is the radius of the guide vane disk (mm), α is the central angle (°) corresponding to the arc-shaped adjustment hole, and Z is the exponent coefficient, which is an empirical coefficient obtained through experiments.

[0058] Step 3: Calculate the baseline coefficient k2, k2 = 0.812Qd / P;

[0059] In the formula, Qd is the design flow rate (m3 / min) and P is the rated power (kW).

[0060] Step 4: Adjust the optimal angle β, β = k1·n a (T0 / T) b ·k2 c ·η d ;

[0061] In the formula, β is the angle between the guide vane blade 101 and the corresponding radius of the tongue point, n is the vacuum pump speed (r / min), T is the actual gas temperature (K), T0 is the standard operating temperature (K), η is the vacuum pump efficiency, k1 and k2 are reference coefficients (determined according to the pump type), and a, b, c, and d are exponential coefficients (reflecting the sensitivity of each parameter to β). Increased temperature leads to changes in gas viscosity and density; therefore, this invention corrects β through the (T0 / T) term to compensate for the influence of temperature on the flow trajectory. It should also be noted that in the practical application of this invention, β values ​​under different operating conditions need to be collected experimentally, and the least squares method is used to fit the coefficients (k1, a, b, c, d) to improve the adaptability of the formula to specific pump types.

[0062] Step 5: First, align the guide vane blade 101 with the tongue. At this time, the angle β between the guide vane blade 101 and the corresponding radius of the tongue point is 0°. Then, rotate the guide vane disk 102 clockwise until the angle β between the guide vane blade 101 and the corresponding radius of the tongue point is the same as the optimal angle β obtained in step 4.

[0063] Step 6: Adjust the clearance between the impeller and the guide vanes, controlling the radial clearance between them within the range of 0.015-0.03D, where D is the impeller diameter. Controlling the radial clearance within this range is to avoid interference between the two and reduce leakage losses during vacuum pump operation.

[0064] The structural features, design, and adjustment method of one embodiment of the present invention have been described above with reference to the accompanying drawings. In general, compared with existing impeller-type vacuum pumps with guide vane structures, the present invention employs an adjustable angle between the guide vane blades and the corresponding radius of the tongue point within the pump body. This ensures efficient kinetic energy conversion and flow field rectification under complex operating conditions, significantly improving the gas delivery efficiency and equipment reliability of the vacuum pump.

Claims

1. A guide vane structure for an impeller-type vacuum pump, comprising a guide vane, a rear cover plate, and an impeller, wherein the guide vane is composed of a guide vane disk and multiple guide vane blades, the multiple guide vane blades being located on one side of the guide vane disk and integrally formed with the guide vane disk, and the multiple guide vane blades being symmetrically arranged around the impeller shaft as an axis of symmetry; characterized in that: An annular guide vane groove is provided on the rear cover plate, and an arc-shaped adjustment hole is provided inside the annular guide vane groove. The inner wall of the arc-shaped adjustment hole is hardened. The shape, size, and depth of the annular guide vane groove match the shape, size, and thickness of the guide vane disc, which is installed inside the annular guide vane groove. The guide vane disc is provided with threaded holes, which are connected and fixed to the rear cover plate through the threaded holes, the arc-shaped adjustment hole, and the engagement of bolts and nuts. By selecting different fastening positions of the bolts and nuts on the arc-shaped adjustment hole, the included angle between the guide vane blade and the corresponding radius of the tongue point in the pump body can be adjusted. The central angle α corresponding to the arc-shaped adjustment hole is 360° / m, where m represents the number of guide vane blades. The number of arc-shaped adjustment holes is x, and the x arc-shaped adjustment holes are symmetrically distributed in the annular guide vane groove with the impeller shaft as the axis of symmetry. x is an integer, and 2≤x≤m.

2. The guide vane structure of the impeller-type vacuum pump as described in claim 1, characterized in that: The guide vane has 5 blades.

3. The guide vane structure of the impeller-type vacuum pump as described in claim 1, characterized in that: A scale marking is provided on the edge of the arc-shaped adjustment hole.

4. The guide vane structure of the impeller-type vacuum pump as described in any one of claims 1 to 3, characterized in that: The bolt is a wing bolt.

5. A method for adjusting the guide vane structure of an impeller vacuum pump, characterized in that, Includes the following steps: Step 1: A ring-shaped guide vane groove is formed on the back cover plate. The shape, size, and depth of the ring-shaped guide vane groove match the shape, size, and thickness of the guide vane disk. An arc-shaped adjustment hole is opened in the ring-shaped guide vane groove. The central angle α corresponding to the arc-shaped adjustment hole is 360° / m, where m is the number of guide vane blades, and the number of arc-shaped adjustment holes is x, where x is an integer and 2≤x≤m. The x arc-shaped adjustment holes are symmetrically distributed in the ring-shaped guide vane groove with the impeller shaft as the axis of symmetry. Step 2: Calculate the baseline coefficient k1, k1 = α / R z·cosα ; In the formula, R is the radius of the guide vane disk, α is the central angle corresponding to the arc-shaped adjustment hole, and z is the exponential coefficient; Step 3: Calculate the baseline coefficient k2, k2 = 0.812Qd / P; In the formula, Qd is the design flow rate and P is the rated power; Step 4: Adjust the optimal angle β, β = k1·n a (T0 / T) b ·k2 c ·η d ; In the formula, β is the angle between the guide vane blade and the corresponding radius of the tongue point, n is the vacuum pump speed, T is the actual gas temperature, and T0 is the standard operating temperature. η is the efficiency of the vacuum pump; k1 and k2 are the baseline coefficients; a, b, c, and d are the exponential coefficients. Step 5: First, align the guide vane blade with the tongue. At this point, the angle β between the corresponding radius of the guide vane blade and the tongue is 0°. Then, rotate the guide vane disk clockwise until the angle β between the corresponding radius of the guide vane blade and the tongue is the same as the optimal angle β obtained in Step 4.

6. The method for adjusting the guide vane structure of the impeller vacuum pump as described in claim 5, characterized in that, It also includes step 6: adjusting the gap between the impeller and the guide vane blades, controlling the radial gap between them within the range of 0.015-0.03D, where D is the impeller diameter.

7. The method for adjusting the guide vane structure of the impeller vacuum pump as described in claim 5 or 6, characterized in that: When performing step 1, the inner wall of the arc-shaped adjustment hole is hardened.

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