A pump casing capable of balancing the axial force of a centrifugal pump

Abstract

The present invention relates to a pump casing capable of balancing the axial force of a centrifugal pump, comprising a pump casing, wherein a plurality of arc-shaped convex blocks are installed on the inner surface of the front pump chamber of the pump casing facing the impeller front cover plate, wherein the cross-sectional contour line of the arc-shaped convex block is a smooth convex curve, wherein the top of the convex area of ​​the smooth convex curve is an arc line parallel to the generatrix of the impeller front cover plate, and a gap is left between the top of the convex area of ​​the arc-shaped convex block and the impeller front cover plate. The pump casing of the present invention can ensure that the axial force is stably reduced throughout the life cycle of the pump.

Description

Technical Field

[0001] The invention relates to the technical field of centrifugal pumps, and in particular to a pump casing capable of balancing the axial force of a centrifugal pump. Background Art

[0002] Centrifugal pumps are general-purpose machinery and are widely used in agricultural irrigation, water supply and drainage, metallurgy and chemical industry, military industry and aviation, etc. Therefore, it is very important to improve the stability of centrifugal pump operation and the service life of the pump.

[0003] Overcoming the impeller axial force has always been an issue that cannot be ignored in the design process of centrifugal pumps, especially in the field of single-stage end-suction centrifugal pumps and multi-stage centrifugal pumps. The axial force has become an important factor affecting the life of the pump. The impeller axial force mainly includes: the axial force generated by the asymmetry of the front and rear covers of the impeller, the axial force caused by the shaft end and other structures, the dynamic reaction force and other factors affecting the axial force. Among them, the axial force generated by the asymmetry of the front and rear covers of the impeller is the main component, and the direction points to the inlet of the impeller.

[0004] Generally speaking, the commonly used methods for balancing the axial force include setting balancing holes and balancing discs on the impeller. The balancing holes can only partially reduce the axial force, and the bearings are still needed to bear the remaining axial force. The deep groove ball bearings commonly used in the pump field can bear part of the axial force, but this force cannot be too large, otherwise it will reduce the service life of the bearing. The working principle of the balancing disc is to automatically adjust the size of the balancing force through the gap between the balancing disc and the balancing disc seat to achieve the purpose of balancing the axial force; however, this design not only complicates the structure of the pump, but also seriously affects the stability and safety of the pump operation due to the mutual wear between the balancing disc and the balancing disc seat in actual operation. Summary of the invention

[0005] The present invention mainly aims at the problem that the axial force of the existing centrifugal pump is too large during operation, and provides a pump casing capable of balancing the axial force of the centrifugal pump.

[0006] To achieve the above-mentioned purpose of the invention, the technical solution adopted by the present invention is: a pump casing capable of balancing the axial force of a centrifugal pump, comprising a pump casing, wherein a plurality of arc-shaped convex blocks are installed on the inner surface of the front pump chamber of the pump casing facing the impeller front cover plate, the cross-sectional contour line of the arc-shaped convex block is a smooth convex curve, the top of the convex area of ​​the smooth convex curve is an arc line parallel to the generatrix of the impeller front cover plate, and a gap is left between the top of the convex area of ​​the arc-shaped convex block and the impeller front cover plate.

[0007] In the above solution, the minimum distance between the top of the raised area of ​​the arc-shaped convex block and the impeller front cover plate is 1 mm.

[0008] In the above solution, the arc-shaped convex block and the inner surface of the front pump chamber are detachably connected.

[0009] In the above scheme, bolt holes are provided on the arc-shaped convex block, and the inner surface of the front pump chamber and the arc-shaped convex block are detachably connected via hexagon socket bolts.

[0010] In the above solution, the material hardness of the arc-shaped convex block is lower than the material hardness of the impeller front cover plate.

[0011] The beneficial effects of the present invention are as follows: (1) The structure is simple. It is only necessary to install an appropriate number of arc-shaped convex blocks in the front pump chamber of the pump housing as required, without the need for other additional structures, such as a balance plate, a balance plate seat, etc., which can significantly reduce the axial force on the impeller. (2) Since the liquid film area formed by the impeller and the arc-shaped convex during rotation is a high-pressure area, and the smaller the thickness of the liquid film, the higher the pressure, the high pressure acts on the impeller front cover plate, while reducing the axial force of the impeller, it can also effectively reduce the axial and radial movement of the impeller. (3) The hardness of the arc-shaped convex block material is softer than that of the impeller material, which can effectively prevent the wear of the impeller and transfer the possible wear to the arc-shaped convex block, which can be easily replaced by bolt connection. (4) Such a design can ensure that the axial force is stably reduced throughout the life cycle of the pump. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 Schematic diagram of the thin film lubrication principle of water-lubricated bearings.

[0013] Figure 2 It is a schematic diagram of the appearance of an existing centrifugal pump casing.

[0014] Figure 3 for Figure 2 AA section view.

[0015] Figure 4 It is a schematic diagram of the installation of the impeller front cover plate and the arc-shaped convex block.

[0016] Figure 5 Schematic diagram of the appearance of the arc-shaped convex block.

[0017] Figure 6 This is a cross-sectional schematic diagram of the installation of the impeller and the arc-shaped convex block inside the improved pump.

[0018] Figure 7 This is a three-dimensional schematic diagram of the relative position of the interior of the improved pump casing and the arc-shaped convex block.

[0019] Figure 8 To adjust the pressure cloud map on the surface of the front cover plate of the front impeller.

[0020] Fig. 9 To adjust the pressure cloud map on the surface of the impeller front cover.

[0021] Figure numerals: 1. sleeve, 2. shaft, 3. contraction area, 4. diffusion area, 5. water, 6. pump body, 7. bolt hole, 8. arc-shaped convex block, 9. hexagon socket bolt, 10. inner surface of the front pump chamber, 11. impeller, 12. impeller front cover plate, 13. impeller inlet end. DETAILED DESCRIPTION

[0022] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0023] The present invention is inspired by Figure 1 The schematic diagram of the thin film lubrication principle of water-lubricated bearings is shown in the figure, where O' is the axis of the shaft sleeve, O is the axis of the shaft, W is the external load, e is the eccentricity of the shaft, R is the radius of the shaft, and ω is the angular velocity of the shaft. During the high-speed operation of the water-lubricated bearing, due to the viscosity of water, as the shaft rotates, it will gradually squeeze to form a high-pressure contraction area. The increased fluid pressure in the contraction area separates the bearing from the rotor through a layer of liquid film, which is balanced with the external load acting on the rotor, and the fluid properties in this area remain unchanged.

[0024] According to the generation mechanism of the lubricating film of the water-lubricated bearing, this embodiment improves the existing centrifugal pump casing (such as Figure 2 and Figure 3 As shown) Figure 4 The figure shows the installation diagram of the pump casing 6 and the arc-shaped convex block of an improved single extreme suction horizontal centrifugal pump. Two bolt holes are processed at intervals of 60 degrees on the inner surface 10 of the front pump chamber of the pump casing 6. The size of the bolt holes matches the hexagon socket bolts 9 used to install and fix the arc-shaped convex block 8 later. Figure 5 As shown, the cross-sectional profile of the arc-shaped convex block 8 is a smooth convex curve, the top of the convex area is an arc parallel to the generatrix of the impeller front cover plate 12, and the left and right parts of the block are each processed with a bolt hole 7, which is a buried hole. Figure 6 and Figure 7The installation method shown is installed on the inner surface 10 of the front pump chamber of the pump housing by means of hexagon socket bolts, wherein the cross-sectional contour line of each arc-shaped convex block 8 is a smooth convex curve, and the top of the convex area of ​​the smooth convex curve is an arc line parallel to the generatrix of the impeller front cover plate 12 installed on the impeller 11. After the arc-shaped convex block 8 is installed, the impeller 10 is installed. After the entire pump is assembled, the minimum distance between the relative position of the impeller front cover plate 11 and the arc-shaped convex block 8 is 1mm. During the high-speed operation of the pump, due to the viscosity of water, during the rotation of the impeller, a gradually shrinking and expanding area similar to that involved in the thin film lubrication principle of water-lubricated bearings is formed between the inner surface 10 of the front pump chamber of the pump housing and the impeller front cover plate 12. The high pressure in the gradually shrinking area acts on the impeller front cover plate 12, which can significantly reduce the axial force directed to the impeller inlet end 13 of the impeller 11.

[0025] By using ANSYS CFX software to simulate the flow field inside the pump involved in this embodiment, we can analyze the actual technical effect of the arc-shaped convex block involved in this embodiment after installation. Figure 7 The figure shows the pressure cloud diagram on the impeller front cover surface when the arc-shaped convex block is not installed. Figure 8 This is the pressure cloud map on the impeller front cover plate surface after installing the arc-shaped convex block. By comparing the two cloud maps, it can be found that the pressure on the impeller front cover plate surface increases significantly after installing the arc-shaped convex block. Through simulation calculation, it is obtained that the axial force on the impeller is reduced from 151.3N to 13.1N, and the direction is pointing to the impeller inlet.

[0026] During the period from when the pump is turned on to when a stable speed is reached, since the speed of the pump is relatively low, a stable high-pressure liquid film cannot be formed between the impeller front cover plate 12 and the arc-shaped convex block 8, so the impeller front cover plate 12 and the arc-shaped convex block 8 are easily in contact, resulting in wear of the impeller front cover plate 12. In order to solve this problem, the arc-shaped convex block 8 in the present invention is made of a material with a lower hardness than the impeller front cover plate 12, such as copper, to prevent the impeller front cover plate 12 from affecting the working performance of the impeller due to wear. The arc-shaped convex block 8 is firmly mounted on the inner surface 10 of the front pump chamber of the pump casing by the hexagon socket bolts 9, so it can be easily replaced. At the same time, the number and arrangement of the arc-shaped convex blocks 8 can be adjusted according to the needs of special working conditions, so that the axial force is reasonably reduced and the pump can be ensured to run smoothly.

Claims

1. A pump casing capable of balancing the axial force of a centrifugal pump, comprising a pump casing, characterized in that: A plurality of arcuate convex blocks (8) are installed on the inner surface (10) of the front pump chamber of the pump housing facing the impeller front cover plate (12), without requiring any other additional structure, and capable of reducing the axial force on the impeller; the cross-sectional contour line of the arcuate convex block (8) is a smooth convex curve; the top of the convex area of ​​the smooth convex curve is an arc line parallel to the generatrix of the impeller front cover plate (12); a gap is left between the top of the convex area of ​​the arcuate convex block (8) and the impeller front cover plate (12); the material hardness of the arcuate convex block (8) is lower than the material hardness of the impeller front cover plate (12); and the arcuate convex block (8) and the inner surface (10) of the front pump chamber are detachably connected.

2. A pump casing capable of balancing the axial force of a centrifugal pump according to claim 1, characterized in that: The minimum distance between the top of the raised area of ​​the arc-shaped convex block (8) and the impeller front cover plate (12) is 1 mm.

3. A pump casing capable of balancing the axial force of a centrifugal pump according to claim 1, characterized in that: The arc-shaped convex block (8) is provided with a bolt hole (7), and the inner surface (10) of the front pump chamber and the arc-shaped convex block (8) are detachably connected via a hexagon socket bolt (9).

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