Low-specific-speed vertical mixed-flow pump

Abstract

The utility model discloses a low-specific-speed vertical mixed-flow pump, which relates to the technical field of fluid machinery and is additionally provided with a sealing ring, a radial floating connecting mechanism, a filling block and an elastic sealing ring on the basis of comprising a suction horn mouth, an impeller and an impeller chamber. The sealing ring is in radial floating connection with the suction horn mouth through a mechanism formed by the cylindrical pin and the pin hole, so that the sealing ring can adapt to micro eccentricity of the impeller, the sealing radial gap between the sealing ring and the suction horn mouth is allowed to be reduced to 0.15-0.2 mm, and the volume loss is remarkably reduced. The filling block is fixed to the suction horn mouth and fills an annular space between the impeller front cover plate and the impeller chamber, and vortex generation and vibration are effectively restrained. The elastic sealing ring is contained in an axial gap between the filling block and the end face of the sealing ring and provides axial sealing and floating buffering. According to the utility model, the efficiency and the stability of the pump are greatly improved while the operation reliability is ensured, and the problems of low efficiency, easy vibration and easy sealing damage of the pump in the prior art are solved.

Description

TECHNICAL FIELD

[0001] The utility model relates to fluid machinery technical field, concretely relates to a low specific speed vertical mixed flow pump. BACKGROUND

[0002] The low specific speed vertical mixed flow pump is widely applied in the fields of electric power, steel, city water supply and drainage, agricultural irrigation and the like due to the characteristics of small land occupation, large flow, low civil engineering cost and simple maintenance. However, in actual application, it is found that the existing low specific speed vertical mixed flow pump structure has several defects, which affect the operation efficiency and stability of the pump, and the defects are embodied in the following three aspects.

[0003] First, vortex is easily generated in the front cover plate area of the impeller, resulting in vibration and efficiency reduction. In the existing structure, a large annular space is usually reserved between the inner wall of the impeller chamber and the outer surface of the rotating front cover plate of the impeller. When the water pump is operated under a small flow condition, the flow state in the annular area deteriorates, and unstable vortex is easily formed. These vortexes not only consume additional energy, resulting in reduced water pump efficiency, but also induce strong vibration of the pump set, threatening the long-term safe and stable operation of the equipment.

[0004] Second, the gap leakage loss at the sealing ring is large. In order to ensure the operation safety and prevent the impeller from rubbing against the stationary parts, a large fitting gap (for example, 0.275-0.327 mm) is usually provided between the sealing ring (or called port ring) and the sealing fitting surface of the impeller hub in the existing structure. The existence of the gap provides a channel for the fluid in the high pressure area to leak to the low pressure area, causing significant volume loss and directly reducing the operation efficiency of the water pump.

[0005] In summary, the structural defects of the existing technology result in low operation efficiency, high vibration and noise risk, and poor partial condition adaptability. Therefore, there is an urgent need for a new low specific speed vertical mixed flow pump structure to effectively improve the efficiency and stability of the pump while ensuring operation reliability. UTILITY MODEL CONTENTS

[0006] In view of the problems existing in the above-mentioned prior art, the utility model provides a new low specific speed vertical mixed flow pump structure to effectively improve the efficiency and stability of the pump while ensuring operation reliability.

[0007] The technical scheme adopted by the utility model is as follows: a low specific speed vertical mixed flow pump, comprising a suction horn, an impeller, an impeller chamber, and further comprising:

[0008] a sealing ring, the inner hole of which is arranged around the sealing fitting surface of the impeller, and a radial gap is formed between the two;

[0009] a radial floating connecting mechanism is arranged between the sealing ring and the suction bellmouth, so that the sealing ring can be displaced in the radial direction relative to the suction bellmouth;

[0010] a filling block is fixedly connected to the suction bellmouth by means of screws and is located in the impeller chamber, and fills the annular space between the front cover plate of the impeller and the inner wall of the impeller chamber;

[0011] the axial end surface of the filling block towards the front cover plate of the impeller is arranged in axial spacing with the corresponding axial end surface of the sealing ring, so as to form an axial gap;

[0012] a resilient sealing ring is accommodated in the axial gap, and the outer diameter side of the resilient sealing ring is in contact with the filling block and the sealing ring and is in a compressed state.

[0013] Further, the radial floating connecting mechanism comprises a plurality of cylindrical pins uniformly distributed on the suction bellmouth in the circumferential direction, and a plurality of mounting pin holes corresponding to the cylindrical pins are arranged on the sealing ring; the diameter of the mounting pin hole is greater than the diameter of the cylindrical pin.

[0014] Further, the diameter of the mounting pin hole is greater than the diameter of the cylindrical pin by 2mm.

[0015] Further, the axial gap between the corresponding end surfaces of the filling block and the sealing ring is not less than 0.1mm.

[0016] Further, the radial gap between the inner hole of the sealing ring and the sealing matching surface of the impeller is 0.15mm to 0.2mm.

[0017] Further, the resilient sealing ring is an O-ring.

[0018] Further, the hole diameter of the inner hole of the sealing ring near the end of the suction bellmouth is smaller than the hole diameter near the end of the impeller chamber; the shape of the sealing matching surface of the impeller is adapted thereto.

[0019] Further, the inner hole wall of the sealing ring and the sealing matching surface of the impeller are provided with a plurality of annular sealing teeth and annular expansion cavities arranged alternately in the axial direction, and the sealing teeth and the expansion cavities of the two are staggered and corresponded in the axial direction, and together constitute a labyrinth seal structure.

[0020] Further, the intersection between the outer circular surface of the sealing ring and the lower end surface matched with the suction bellmouth is formed as a right-angled edge; the suction bellmouth is provided with a matching structure adapted to the right-angled edge.

[0021] The beneficial effects of the utility model lie in:

[0022] (1) By filling the original annular space between the front cover plate of the impeller and the inner wall of the impeller chamber with the filling block fixed to the suction horn, the flow cross section of the region is significantly reduced, the space conditions for vortex generation and development are destroyed, the flow state of the region under partial working conditions (especially small flow) is improved, the formation of unstable vortex is effectively inhibited, thereby reducing the vibration and noise caused thereby, and the running stability and reliability of the pump set under different working conditions are improved;

[0023] (2) The technical scheme combining "precise gap design" and "floating anti-wear mechanism" is adopted, on the one hand, the radial gap between the sealing ring and the impeller is reduced to 0.15-0.2mm, thereby directly reducing the leakage amount of the high-pressure medium flowing back through the gap and reducing the volume loss; on the other hand, through the radial floating connection mechanism composed of the cylindrical pin and the mounting pin hole, the sealing ring has limited automatic adjustment capability in the radial direction, so that when the impeller is slightly eccentric due to manufacturing, installation or operation, the sealing ring can be adaptively displaced, thereby avoiding rigid friction or scratching with the impeller, so that the precise gap is maintained for a long time under the premise of ensuring high reliability, and high efficiency is continuously maintained;

[0024] (3) The radial floating connection mechanism and the elastic sealing ring accommodated in the axial gap together form a self-adaptive system, the elastic sealing ring not only provides axial sealing, but also provides buffering for the radial floating of the sealing ring, thereby ensuring the smoothness of the floating process; further, by adopting the sealing ring with gradually changed inner hole diameter and the impeller sealing surface matched therewith, the flow can be optimized; more preferably, by arranging the labyrinth seal structure composed of the alternately arranged annular sealing teeth and the expansion cavity, the leakage path is greatly lengthened, the flow resistance is increased, the sealing effect is further improved, and multiple sealing protection is realized;

[0025] (4) The right-angle edge of the outer edge of the sealing ring and the matching structure on the suction horn form effective end face sealing, can form linear contact or extremely narrow strip-shaped contact in the assembled state, generate higher local specific sealing pressure, and effectively prevent the high-pressure medium at the outlet of the impeller from flowing into the inlet of the impeller through the front cover plate. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is a partial axial cross-sectional structural schematic view of a low specific speed vertical mixed flow pump of an embodiment of the present application.

[0027] Figure 2 is a partial axial cross-sectional structural schematic view of the corresponding part of a low specific speed vertical mixed flow pump of the prior art as a comparison.

[0028] In the figure: 1, filling block; 2, screw; 3, elastic sealing ring; 4, suction horn; 5, sealing ring; 6, cylindrical pin; 7, impeller. DETAILED DESCRIPTION

[0029] For the convenience of understanding the utility model, the following will combine with the description drawings and the preferred embodiments to make more comprehensive and detailed description of the utility model, but the protection scope of the utility model is not limited to the following specific embodiments.

[0030] As Figure 1 The utility model discloses a low specific speed vertical mixed flow pump, mainly includes the suction horn 4, impeller 7, impeller chamber and guide vane body etc. conventional components. Its core improvement is integrated in the suction horn 4 one set of optimization assembly, and this assembly is mainly by sealing ring 5, radial floating connection mechanism, filler block 1 and elastic sealing ring 3 constitute.

[0031] The sealing ring 5 is sleeved on the hub sealing fit surface outside of impeller 7, and the precise radial operation gap is formed between the two. The radial gap is significantly reduced, and can be controlled between about 0.15mm to 0.2mm, to directly reduce the medium leakage amount through here, thereby reducing the volume loss.

[0032] In order to realize such small gap and ensure the operation safety, prevent wear and tear, the utility model sets up radial floating connection mechanism between sealing ring 5 and stationary suction horn 4. In the embodiment, one preferred implementation of the mechanism is that a plurality of fixed cylindrical pins 6 are uniformly distributed on the end face of suction horn 4 in the circumferential direction. Correspondingly, a plurality of mounting pin holes corresponding to the positions of cylindrical pins 6 are formed on the sealing ring 5, and the diameter of the mounting pin holes is designed to be larger than the diameter of the cylindrical pins 6 (for example, the diameter difference is about 2mm). This matching mode enables the sealing ring 5 to be guided by the cylindrical pins 6 and have a limited floating displacement space in the radial direction. When the impeller 7 produces a small amount of eccentricity due to installation or operation, the sealing ring 5 can adaptively offset, avoiding rigid friction or scratching with the high-speed rotating impeller 7, thereby maintaining the above-mentioned precise gap for a long time under the premise of ensuring high reliability.

[0033] In order to further optimize the flow state and solve the problem that the annular space between the impeller front cover plate and the inner wall of the impeller chamber in the traditional structure is prone to vortex, the utility model adds a filler block 1. The filler block 1 is fixedly installed on the suction horn 4 by screws 2, and the body is located in the impeller chamber, filling the annular space between the impeller front cover plate of the impeller 7 and the inner wall of the impeller chamber, significantly reducing the flow cross-sectional area and space volume here, fundamentally destroying the conditions for vortex generation and development, helping to improve the flow stability under partial working conditions and suppress vibration.

[0034] The axial end face of the filling block 1 on the side of the impeller front cover plate is spaced apart from the corresponding axial end face of the sealing ring 5 in the axial direction to form an axial gap. The axial gap contains an elastic sealing ring 3, which is preferably an O-ring in this embodiment. The outer diameter side of the elastic sealing ring 3 is in contact with the filling block 1 and the sealing ring 5 and is in a certain compression state. The role of the elastic sealing ring 3 is to achieve auxiliary sealing in the axial direction, and to provide necessary buffer for the radial floating of the sealing ring 5, making the entire floating adjustment process more smooth and reliable. The size of the axial gap can be designed to be not less than 0.1 mm, for example, to reserve space for the compression and work of the elastic sealing ring 3.

[0035] As a more preferred embodiment, the inner hole of the sealing ring 5 and the sealing surface of the impeller 7 can be configured as a high-efficiency labyrinth seal structure. Specifically, the inner hole wall of the sealing ring 5 and the sealing surface of the impeller 7 are processed with a plurality of annular sealing teeth and annular expansion cavities arranged alternately in the axial direction. Moreover, the sealing teeth on the sealing ring 5 and the expansion cavities on the impeller 7, and the expansion cavities on the sealing ring 5 and the sealing teeth on the impeller 7 are staggered in the axial direction.

[0036] Preferably, to realize the above-mentioned labyrinth seal structure and facilitate processing and matching, the inner hole of the sealing ring 5 can be designed as follows: the hole diameter near the end of the suction bell mouth 4 is smaller than the hole diameter near the end of the impeller chamber, forming a stepped or tapered base; the shape of the sealing surface on the impeller 7 is also adapted accordingly. This labyrinth seal structure creates a very tortuous leakage channel in a very small design gap (0.15mm to 0.2mm), which greatly increases the leakage resistance, thereby achieving the main purpose of reducing the gap to reduce leakage while further significantly improving the reliability and effectiveness of the seal.

[0037] In addition, on the outer edge of the sealing ring 5, a right-angled edge (i.e. a sharp corner) is formed at the intersection of the outer circular surface and the axial end face (the lower end face in the figure) that matches the suction bell mouth 4. Correspondingly, the suction bell mouth 4 is provided with a matching structure (such as a corresponding step or groove) that precisely matches the right-angled edge. Through the right-angled edge sealing pair, the backflow of high-pressure medium from the impeller outlet side along the assembly gap between the outer circular surface of the sealing ring 5 and the suction bell mouth 4 to the low-pressure area of the impeller inlet can be effectively prevented, forming another important sealing barrier.

[0038] As a comparison, Figure 2 A common structure in the prior art is shown. As can be seen, there is a large annular cavity between the impeller front cover plate and the pump shell (impeller chamber), which is easy to form a vortex; at the same time, the sealing ring is fixedly installed, and the matching gap between the sealing ring and the impeller is relatively large (usually 0.275-0.327mm), and has no self-adaptive floating ability.

[0039] The utility model discloses through above-mentioned integrated structure innovation, will " precision gap seal " " radial floating anti -wear " " space filling suppress vortex " and " multiple sealing guarantee " etc.

[0040] The above is only the preferred embodiment of the utility model, but the protection scope of the utility model is not limited to this, any skilled person in the art can make equivalent replacement or change according to the technical scheme and the utility model concept of the utility model within the technical range disclosed by the utility model, and all should be covered in the protection scope of the utility model.

Claims

1. A low specific speed vertical mixed flow pump comprising a suction bell mouth (4), an impeller (7), an impeller chamber, characterized in that, Also comprising: a sealing ring (5) with an inner hole surrounding the sealing surface of the impeller (7), forming a radial gap between them; a radial floating connection mechanism between the sealing ring (5) and the suction bell (4), allowing the sealing ring (5) to displace radially relative to the suction bell (4); a filling block (1) fixed to the suction bell (4) by screws (2) and located in the impeller chamber, filling the annular space between the front cover plate of the impeller (7) and the inner wall of the impeller chamber; the axial end surface of the filling block (1) towards the front cover plate is axially spaced from the corresponding axial end surface of the sealing ring (5), forming an axial gap; a resilient sealing ring (3) accommodated in the axial gap, with its outer diameter side in contact with the filling block (1) and the sealing ring (5) and in a compressed state.

2. A low specific speed vertical mixed flow pump according to claim 1, characterized in that The radial floating connection mechanism includes a plurality of cylindrical pins (6) evenly distributed on the suction bell (4) and a plurality of mounting pin holes corresponding to the sealing ring (5); the diameter of the mounting pin hole is larger than the diameter of the cylindrical pin (6).

3. A low specific speed vertical mixed flow pump according to claim 2, wherein The diameter of the mounting pin hole is 2mm larger than the diameter of the cylindrical pin (6).

4. A low specific speed vertical mixed flow pump according to claim 1, wherein The axial gap between the corresponding end surfaces of the filling block (1) and the sealing ring (5) is not less than 0.1mm.

5. A low specific speed vertical mixed flow pump according to claim 1, wherein The radial gap between the inner hole of the sealing ring (5) and the sealing surface of the impeller (7) is 0.15mm to 0.2mm.

6. A low specific speed vertical mixed flow pump according to claim 1, wherein The resilient sealing ring (3) is an O-ring.

7. A low specific speed vertical mixed flow pump as claimed in claim 1, wherein, The hole diameter of the inner hole of the sealing ring (5) near one end of the suction bell (4) is smaller than that near the other end of the impeller chamber; the shape of the sealing surface of the impeller (7) is adapted to it.

8. A low specific speed vertical mixed flow pump according to claim 7, characterized in that The inner hole wall of the sealing ring (5) and the sealing surface of the impeller (7) are provided with a plurality of annular sealing teeth and annular expansion cavities arranged axially alternately, and the sealing teeth and expansion cavities of the two are axially staggered and correspond to each other, together forming a labyrinth seal structure.

9. A low specific speed vertical mixed flow pump according to any one of claims 1 to 8, characterized in that The intersection of the outer circular surface of the sealing ring (5) and the lower end surface matched with the suction bell (4) forms a right-angled edge; the suction bell (4) is provided with a matching structure adapted to the right-angled edge.

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