Balancing disc composite structure

Abstract

The utility model discloses a balance disc composite structure. The balance disc one side processing multistage labyrinth surface is formed with the inner side pressure recovery groove pairing by throttle ring and is formed with the section pressure drop and chamber dissipation by arranging from outside to inside and adopting the distribution of small outside and big inside of nominal axial clearance. The outer edge and inner edge are provided with the edge protection to optimize the inlet and outlet transition. The balance disc and the balance disc seat are fixed through the pair of coaxial holes and the screw. The structure can reduce the leakage and the outer edge jet erosion, reduce the heating, improve the axial force balance stability and the life, and is convenient for manufacturing assembly and maintenance replacement.

Description

Technical Field

[0001] This utility model relates to the technical field of axial force balancing and leakage limiting throttling structure for centrifugal pumps, and in particular to a composite structure of a balance disc. Background Technology

[0002] Multistage centrifugal pumps generate significant residual axial forces during operation. These forces are typically mitigated by a balance disc, which throttles the high-pressure fluid through a thin gap at the end face to the low-pressure side, creating a reverse hydraulic force. Existing balance discs are mostly integral flat surfaces or simple grooved end faces, which suffer from problems such as concentrated pressure drop due to single-stage throttling, high-speed jetting and localized cavitation at the outer edge, significant end-face erosion and heat generation, sensitivity to form and position errors, high maintenance and replacement costs, and poor reproducibility of throttling performance.

[0003] Among the publicly available solutions, CN201934392U reduces maintenance costs by setting a replaceable wear ring circumferentially on the friction surface, but it does not construct a multi-stage labyrinth structure composed of a throttling ring and a diffuser groove, nor does it adopt the nominal axial clearance distribution with a smaller outer diameter and a larger inner diameter, or a segmented pressure drop mechanism. Therefore, its improvement in leakage suppression, erosion control, and thermal stability is limited. CN222835977U uses an arc-shaped bushing as the contact protection surface, which is a friction protection approach. However, it also does not involve a multi-stage throttling and diffuser chamber combination with a non-contact thin gap, making it difficult to improve pressure drop distribution, outer edge injection and cavitation, and operational stability from a fluid dynamics perspective. In summary, existing solutions mostly focus on replaceability or protection, and lack a composite design that constructs a multi-stage throttling and diffuser unit on the balance disc end face, combined with a nominal axial clearance that is smaller on the outer side and larger on the inner side. Utility Model Content

[0004] The technical problem to be solved by this utility model is to overcome the defects of the prior art and provide a balance disc composite structure. By constructing a throttling and expansion unit array composed of a throttling ring and a diffuser groove on the end face of the balance disc, multi-stage series throttling and chamber dissipation are achieved, reducing leakage, slowing down end face erosion and temperature rise, and improving assembly reproducibility and maintenance convenience.

[0005] To solve the above-mentioned technical problems, this utility model provides the following technical solution:

[0006] This utility model discloses a composite structure for a balance disc, comprising a balance disc 1 and a balance disc base 2. The balance disc 1 is detachably screwed to the balance disc base 2 via several axially arranged fixing holes 3. A labyrinth surface 4 is provided on one side of the balance disc 1. The labyrinth surface 4 is composed of several throttling and expanding units 7 arranged radially from the outside to the inside. Each expanding unit 7 is formed by the cooperation of a throttling ring band 6 and its adjacent inner diffuser groove 5. In the assembled state, the labyrinth surface 4 is positioned opposite to the mating opposing end faces, with a nominal axial clearance between them. The nominal axial clearance at the throttling ring band 6 in each stage of the expanding and expanding unit 7 increases from the outside to the inside to achieve a pressure drop distribution that is higher on the outside and lower on the inside. The nominal axial clearance at the bottom of the diffuser groove 5 is at least three times the nominal axial clearance of the corresponding throttling ring band 6.

[0007] As a preferred technical solution of this utility model, the number of stages of the throttling and expansion unit 7 is three to seven; in each stage, the radial width of the throttling ring band 6 is 0.8 to 1.5 mm, and the radial width of the diffusion groove 5 is 0.5 to 1.0 mm.

[0008] As a preferred embodiment of this utility model, the depth of the diffuser 5 relative to the adjacent throttling ring 6 is 0.25 to 0.60 mm; the sidewall of the diffuser 5 is provided with an inclination of 1° to 3° on each side, the intersection of the bottom of the diffuser 5 and the sidewall is provided with a rounded corner of R0.10 to R0.20 mm, and the edge of the throttling ring 6 facing the fluid is provided with a rounded edge of R0.02 to R0.05 mm.

[0009] As a preferred technical solution of this utility model, the fixing hole 3 is a pair of coaxial holes, which are formed by the relative cooperation of the threaded blind hole provided on the balance disk 1 and the countersunk through hole provided on the balance disk seat 2; the screw passes through the countersunk through hole from the side of the balance disk seat 2 and is screwed into the threaded blind hole to realize the screw connection and fixation of the two; the fixing hole 3 is set with three to six pairs of hole positions, which are evenly distributed along the circumferential direction with the balance disk axis as the center.

[0010] As a preferred technical solution of this utility model, the outer edge and inner edge of the labyrinth surface 4 are provided with guards 8; the nominal axial clearance of the outer edge guard 8 is increased by 0.01 to 0.02 mm compared with the nominal axial clearance at the outermost first-stage throttling ring 6; the nominal axial clearance of the inner edge guard 8 is the same as or greater than the nominal axial clearance at the innermost first-stage throttling ring 6.

[0011] The “nominal axial clearance” referred to in this specification refers to the designed axial distance between the labyrinth surface 4 and the corresponding opposite end face, wherein the local minimum value is taken at the throttling ring 6.

[0012] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0013] 1. Segmented pressure drop and chamber dissipation: The throttling and expansion units 7 are arranged in series, so that the pressure drop is distributed at the multi-stage throttling ring 6 and diffused and dissipated in the diffuser 5, resulting in lower leakage and a smoother pressure drop curve.

[0014] 2. Higher outer and lower inner profile for better erosion resistance: The outer side has a smaller gap, while the inner side gradually increases the gap, which weakens the high-speed jetting and local cavitation at the outer edge, and reduces the heat load and wear of the outer ring.

[0015] 3. Good assembly repeatability: The mating of the fixing holes 3 and their equal spacing along the circumferential direction with the balance disc axis as the center are conducive to torque transmission and position repeatability, making maintenance faster;

[0016] 4. Improved reliability and lifespan: The rounded corners and micro-rounding at the bottom of the groove suppress stress concentration and edge chipping, while the beveled sidewalls facilitate processing and deburring, thus comprehensively improving end face stability;

[0017] 5. Strong compatibility: It does not change the installation boundary and circuit connection method, has good adaptability, and can be used as an upgrade part for existing pump types; Attached Figure Description

[0018] The accompanying drawings are provided to further illustrate the present invention and form part of the specification. They are used together with the embodiments of the present invention to explain the present invention, but do not constitute a limitation thereof. In the drawings:

[0019] Figure 1 This is a cross-sectional view of the overall structure of this utility model;

[0020] Figure 2 This is a front view of the balance disc of this utility model;

[0021] Figure 3 This is a partial view of the maze surface of this utility model;

[0022] In the diagram: 1. Balance disc; 2. Balance disc base; 3. Fixing hole; 4. Labyrinth surface; 5. Diffuser groove; 6. Throttling ring; 7. Throttling and diffuser unit; 8. Edge protector. Detailed Implementation

[0023] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0024] In the attached diagram, all identical reference numerals refer to the same components.

[0025] like Figure 1-3As shown, this utility model provides a composite structure for a balance disc. The balance disc 1 is detachably screwed to the balance disc base 2 via fixing holes 3. The fixing holes 3 are paired coaxial holes: the balance disc 1 has threaded blind holes, and the balance disc base 2 has countersunk through holes that mate with the heads of the screws used. The screw passes through the countersunk through holes from the side of the balance disc base 2 and screws into the threaded blind holes of the balance disc 1, thus achieving screwed connection and fixation. The fixing holes 3 are configured with three to six pairs of holes, evenly distributed along the circumference with the axis of the balance disc as the center.

[0026] A labyrinth surface 4 is machined on one side of the balance disc 1. The labyrinth surface 4 is composed of several expansion units 7 arranged radially from the outside to the inside. Each expansion unit 7 is formed by a throttling ring band 6 and an adjacent diffuser groove 5 on its inner side. In the assembled state, the labyrinth surface 4 is positioned opposite to the mating opposing end faces, with a nominal axial clearance between them. The high-pressure side fluid passes through each stage of the throttling ring band 6 in this clearance and is diffused in the diffuser groove 5 before being guided to the low-pressure side, thereby achieving segmented pressure drop and limiting leakage.

[0027] Preferably, the throttling and diffusing unit 7 has three to seven stages. In each stage, the radial width of the throttling ring band 6 is 0.8 to 1.5 mm, the radial width of the diffuser groove 5 is 0.5 to 1.0 mm, and the groove depth of the diffuser groove 5 relative to the adjacent throttling ring band 6 is 0.25 to 0.60 mm; the nominal axial clearance at the bottom of the diffuser groove 5 is at least three times the nominal axial clearance at the adjacent throttling ring band 6. The sidewalls of the diffuser groove 5 are provided with a slope of 1° to 3° on each side, and the intersection of the bottom of the diffuser groove 5 and the sidewall is provided with a fillet of R0.10 to R0.20 mm; to suppress outer edge jetting and corner chipping, the edges of the throttling ring band 6 facing the fluid are provided with a rounded edge of R0.02 to R0.05 mm. The outer and inner edges of the labyrinth surface 4 are provided with guards 8. The nominal axial clearance of the inner edge guard 8 is the same as or greater than the nominal axial clearance at the innermost first-stage throttling ring 6, to avoid the formation of a first-stage throttling orifice at the inlet and to weaken inlet injection and cavitation. The nominal axial clearance of the outer edge guard 8 is increased by 0.01 to 0.02 mm compared to the nominal axial clearance at the outermost first-stage throttling ring 6, serving as an outlet venting transition zone to reduce shrinkage loss and local heat generation after the final stage. The edge of the guard should be rounded with a radius of 0.03 to 0.05 mm to avoid sharp edges inducing microjet flow.

[0028] Preferably, in a typical six-stage throttling and expansion unit scheme, the nominal axial clearance at the throttling ring band 6 can be set sequentially from the outside to the inside as 0.06, 0.08, 0.10, 0.12, 0.14, and 0.16 mm; the corresponding depth of the diffuser groove 5 is 0.50 mm relative to each stage of the throttling ring band 6 (the nominal axial clearance at the bottom of the groove is the corresponding stage's nominal axial clearance plus 0.50 mm); the typical radial widths of the throttling ring band 6 and the diffuser groove 5 can be 1.5 mm and 0.8 mm, respectively. The above values ​​are only examples and can be adjusted within the range according to the pressure difference, medium, and rotational speed.

[0029] The method of using this utility model is as follows:

[0030] 1. Place the balance disc 1 in the mounting position of the balance disc base 2, aligning it with the coaxial hole of the fixing hole 3;

[0031] 2. Insert screws sequentially from both sides of the balance disc base, ensuring the screw heads mate with the mating surfaces of the countersunk through holes, and screw them into the threaded blind holes of the balance disc 1 to achieve the specified torque;

[0032] 3. Set the nominal axial clearance according to design requirements;

[0033] 4. During operation, the fluid enters the outer side of the labyrinth surface 4 from the high-pressure side, crosses the throttling ring 6 in sequence, and flows to the low-pressure side after diffusing energy in the diffuser 5, thereby achieving the balance of the residual axial force.

[0034] Furthermore, this utility model is not limited to the number of stages and specific dimensions shown in the above embodiments. The number of stages of the throttling expansion unit 7, the width of the throttling ring band 6 and the diffuser groove 5, the side wall slope and the rounded corner size can all be adjusted within the range to adapt to different pressure difference, medium and speed conditions.

[0035] This invention is a composite structure that constructs a multi-stage throttling and diffuser chamber on the end face of a balance disc. It has a simple structure, is easy to process and assemble, and can significantly improve pressure drop distribution and end face stability, reduce leakage and erosion risks, and has good engineering application value.

[0036] Finally, it should be noted that the above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A balance disc composite structure, comprising a balance disc (1) and a balance disc base (2) mounted on one side of the balance disc (1), characterized in that: The balance disk (1) has a labyrinth surface (4) on one side. The labyrinth surface (4) is composed of several expansion units (7) arranged radially from the outside to the inside. Each expansion unit (7) is formed by the cooperation of a throttling ring (6) and a diffuser groove (5) adjacent to its inner side. The balance disk (1) is screwed to the balance disk seat (2) through several fixing holes (3) arranged axially.

2. The composite structure of the balance disc according to claim 1, characterized in that: In the assembled state, the labyrinth surface (4) is arranged opposite to the mating opposing end face, with a nominal axial gap between them; the nominal axial gap at the throttling ring (6) in each level of throttling expansion unit (7) increases from the outside to the inside, so as to achieve a pressure drop distribution with high outside and low inside.

3. The composite structure of the balance disc according to claim 1, characterized in that: The number of stages of the throttling and expansion unit (7) is three to seven; in each stage, the radial width of the throttling ring (6) is 0.8 to 1.5 mm, and the radial width of the diffuser groove (5) is 0.5 to 1.0 mm.

4. The composite structure of the balance disc according to claim 1, characterized in that: The depth of the diffuser groove (5) relative to the adjacent throttling ring (6) is 0.25 to 0.60 mm, and the nominal axial clearance of the bottom of the diffuser groove (5) is at least three times the nominal axial clearance of the corresponding throttling ring (6).

5. The composite structure of the balance disc according to claim 1, characterized in that: The diffuser (5) has a slope of 1° to 3° on each side, and the intersection of the bottom of the diffuser (5) and the side wall has a rounded corner of R0.10 to R0.20 mm. The edge of the throttling ring (6) facing the fluid has a rounded corner of R0.02 to R0.05 mm.

6. The composite structure of the balance disc according to claim 1, characterized in that: The fixing holes (3) are coaxial holes arranged in pairs, which are formed by the threaded blind hole set on the balance disc (1) and the countersunk through hole set on the balance disc seat (2); the screw passes through the countersunk through hole from the side of the balance disc seat (2) and is screwed into the threaded blind hole to fix the balance disc (1) and the balance disc seat (2); the number of fixing holes (3) is three to six pairs, which are evenly distributed along the circumferential direction with the balance disc axis as the center.

7. The composite structure of the balance disc according to claim 1, characterized in that: The outer and inner edges of the labyrinth surface (4) are provided with guards (8); the nominal axial clearance of the outer edge guard (8) is 0.01 to 0.02 mm larger than the nominal axial clearance at the outermost first-level throttling ring (6); the nominal axial clearance of the inner edge guard (8) is the same as or greater than the nominal axial clearance at the innermost first-level throttling ring (6).

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