An umbrella-shaped ring structure for fixing the elastic pad layer on the lower cavity surface of the top cover

Abstract

This utility model discloses an umbrella-shaped ring structure for fixing an elastic pad on the lower cavity surface of a top cover. The structure comprises: a rubber elastic pad (1) completely covering the lower cavity surface of the top cover; an umbrella-shaped steel structure fixing ring (2) below the elastic pad (1), the fixing ring (2) consisting of a concentric circular skeleton and a radial skeleton, forming a support frame that divides the elastic pad (1) into multiple fan-shaped ring structures; and embedded bolts (3) evenly distributed around the fixing ring (2). The bolts (3) press and fix the elastic pad (1) to the lower cavity surface of the top cover (7) using pre-tightening force. Through the combination of the umbrella-shaped fixing ring and the embedded bolts, both fixing the elastic pad and utilizing the pad's damping and vibration reduction function are achieved, thereby effectively reducing abnormal vibrations of the top cover.

Description

Technical Field

[0001] This application relates to the technical field of fluid machinery and engineering equipment, and in particular to an umbrella-shaped ring fixing structure for fixing the elastic pad layer on the lower cavity surface of the top cover. Background Technology

[0002] Vibration occurs in the turbine top cover of different operating zones, and the maintenance costs of the top cover and runner account for the majority of the unit's maintenance expenses. Abnormal vibrations exceeding the specified limits, caused by hydraulic self-excited vibrations due to periodic changes in the labyrinth gap, can lead to the destruction of the entire unit. Currently, many engineering measures are used to mitigate top cover vibration, including structural improvements and reinforcement of the top cover and forced air replenishment. However, the timeliness of air replenishment is insufficient, and the cost of top cover reinforcement is prohibitive. Damping methods have also been used for turbine top covers, such as patents CN202123015442.8 and CN202111463796.0. Considering that the hydraulic vibration source mainly occurs in the lower cavity of the top cover, using the damping effect of rubber to mitigate its vibration is also a feasible solution. However, the deformation of the stationary elastic pad in contact with the high-speed rotating runner can result in either a loss of vibration mitigation effect or, in severe cases, a unit accident. The method of fixing the rubber elastic pad has become an engineering challenge.

[0003] The key to successful elastic padding fixing methods lies in ease of installation, ensuring the integrity of the elastic padding layer, and maximizing the free area to achieve its damping effect. Currently, there are no operational examples of elastic padding reinforcement methods on turbine roofs; similar methods can only be referenced. Rubber fixing techniques, such as those patented in CN202323643987.2, CN202411397759.8, CN202420999719.X, and CN202411183486.7, address the issue of elastic rubber detachment through clamping, adhesion, and slotting methods.

[0004] However, the above-mentioned fixing methods are only applicable to conventional projects. For the narrow, high-pressure water-filled space under the top cover and for large-area planar objects, traditional methods not only have limitations in terms of fixation but also make it difficult to increase the free area of ​​the cushion layer. Therefore, there is an urgent need for a new method for fixing planar elastic cushion layers. Utility Model Content

[0005] The purpose of this utility model is to provide an umbrella-shaped ring structure for fixing the elastic pad layer on the lower cavity surface of the top cover, in order to address the above-mentioned problems. By using the umbrella-shaped fixing ring and the embedded bolt, the structure can both fix the elastic pad layer and give full play to the damping and vibration reduction effect of the pad layer, thereby effectively reducing the abnormal vibration of the top cover.

[0006] The technical solution of this utility model is as follows:

[0007] This utility model discloses an umbrella-shaped ring structure for fixing an elastic pad layer on the lower cavity surface of a top cover, comprising: a rubber elastic pad layer that completely covers the surface of the lower cavity of the top cover; an umbrella-shaped steel structure fixing ring disposed below the elastic pad layer, the fixing ring being composed of a concentric circular skeleton and a radial skeleton, forming a support frame that divides the elastic pad layer into multiple fan-shaped ring structures; and embedded bolts evenly distributed around the fixing ring, the bolts pressing and fixing the elastic pad layer to the surface of the lower cavity of the top cover by a preload.

[0008] Furthermore, the concentric circular skeleton of the umbrella-shaped steel structure fixing ring consists of four staggered annular skeletons, with the radius ratio of adjacent annular skeletons being 1.5.

[0009] Furthermore, the radial skeleton of the umbrella-shaped steel structure fixing ring includes a radial main skeleton arranged at equal 22.5° intervals, and also includes a radial secondary skeleton disposed between adjacent concentric circular skeletons and at the same angle as the radial main skeleton.

[0010] Furthermore, the nut of the embedded bolt adopts a cross-shaped torsion structure, and after pre-tightening, the upper surface of the nut is flush with the upper surface of the umbrella-shaped steel structure fixing ring.

[0011] Furthermore, the bolts are distributed in an equally spaced ring array along the circumference of the umbrella-shaped steel structure fixing ring, and the spacing between adjacent bolts gradually increases in the radial direction.

[0012] Furthermore, the number of bolts in the outer fan ring area of ​​the umbrella-shaped steel structure fixing ring is 8, and the number of bolts in the inner fan ring area is 12.

[0013] Furthermore, the fan-ring structure has a larger free area in the high vibration amplitude region near the crown labyrinth seal of the rotor, and a smaller free area in the high pressure average region near the crown inlet of the rotor.

[0014] Furthermore, the free area of ​​the fan-ring structure can be adjusted by adjusting the spacing between adjacent concentric circular skeletons and the distribution density of the radial skeleton.

[0015] Furthermore, the contact surface between the umbrella-shaped steel structure fixing ring and the elastic pad layer is formed by the pre-tightening force of the bolt to form a flat pressing surface, and the pressing surface, together with the surface of the lower cavity of the top cover and the surface of the upper crown of the rotating wheel, forms a flow channel structure without protrusions.

[0016] In summary, due to the adoption of the above technical solution, the beneficial effects of this utility model are:

[0017] 1. The umbrella-shaped ring structure of the fixed elastic pad on the lower cavity surface of the top cover of this utility model adopts an umbrella-shaped steel structure fixing ring combined with the elastic pad to form a fan ring structure fixed on all four sides. This ensures that the elastic pad does not contact the rotating wheel when deformed, and maximizes the free area of ​​the elastic pad, giving full play to its elastic damping advantage and further improving the vibration reduction effect.

[0018] 2. The umbrella-shaped fixing ring structure of this utility model has a larger free area of ​​the fan ring in the high vibration amplitude region near the labyrinth ring seal and a smaller free area of ​​the fan ring in the high pressure average region near the wheel inlet, thus taking into account both the fixing function and the padding effect.

[0019] 3. In this utility model, the bolt pre-tightening is flush with the fixing ring, and the deformability of the pad layer makes the pressing fixing ring roughly flush with it. The relatively flat surface formed by the three can avoid triggering undesirable flow conditions in the lower cavity of the top cover and avoid increasing the vibration amplitude of the top cover. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of an umbrella-shaped ring structure for fixing the elastic pad layer on the lower cavity surface of the top cover according to the present invention;

[0021] Figure 2 A schematic diagram showing the positional relationship between the top cover, the fixing ring, and the rotating wheel provided in an embodiment of this utility model;

[0022] Figure 3 Cross-sectional view of an embodiment of this utility model;

[0023] Figure 4 A schematic diagram of the arrangement of the fixing rings provided in an embodiment of this utility model;

[0024] Figure 5 A schematic diagram of a bolt and nut provided for an embodiment of this utility model.

[0025] Reference numerals: 1-Elastic pad, 2-Fixing ring, 3-Bolt, 4-Circumferential main frame, 5-Radial main frame, 6-Radial secondary frame, 7-Top cover, 8-Rotator, 9-Rotator upper crown inlet, 10-Rotator upper crown labyrinth seal. Detailed Implementation

[0026] It should be noted that relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0027] The features and performance of this utility model will be further described in detail below with reference to the embodiments.

[0028] like Figure 1 — Figure 5 As shown in the figure, this embodiment describes the design process of an umbrella-shaped ring structure for fixing the elastic pad layer on the lower cavity surface of the top cover, which is used to fix the elastic pad layer and exert its damping and vibration reduction effect.

[0029] Step 1: Determine the thickness and width of the retaining ring;

[0030] The thickness of the retaining ring should take into account both the structural strength and the flatness of the ring formed with the pad. The thickness of the retaining ring is determined by formula (1).

[0031] (1)

[0032] In the formula The thickness of the elastic pad is obtained through conventional design methods, as described in the embodiment. = 20mm, will Substituting into equation (1), we obtain = 4mm ~ 6mm, here we choose 6mm.

[0033] The width of the retaining ring skeleton should take into account both structural strength and the specifications of the bolts applicable to this example. The width of the retaining ring skeleton is determined by formula (2).

[0034] (2)

[0035] In the formula In order to select the diameter of the bolt and nut, in the embodiment... = 10mm, will Substituting into equation (2), we obtain = 20mm ~ 25mm, here we choose 25mm.

[0036] Step 2: Determine the circumferential and radial skeleton distribution of the fixed ring;

[0037] The determination of the number and radius of the circumferential skeleton needs to consider both its fixing function and the function of the padding layer. The number of circumferential skeletons needs to be determined based on the vertical projection length from the inlet of the rotating wheel in the lower cavity of the top cover to the labyrinth seal. Set the number of fan rings as recommended. n = In the embodiments = 2182mm, = 1232mm, Choose 4 circumferential skeletons.

[0038] The circumferential skeleton radius is determined by equations (3)-(5).

[0039] (3)

[0040] (4)

[0041] (5)

[0042] In the formula α Take 0.8, x Let be the width of the first-layer fan ring. Substituting the parameter into equation (3), we obtain... = 1605mm, =1978mm.

[0043] The radial primary and secondary skeletons need to have their spacing angle β determined, which is recommended to be no greater than 45°. In this embodiment, the angle β is taken as 22.5°, and the radial primary and secondary skeletons are staggered at an angle of 11.25°.

[0044] Step 3: Determine the bolt distribution;

[0045] Bolts are evenly spaced along the circumference of the fixing ring and staggered radially to secure the different padding layers around the fan rings. It is recommended to use 8 bolts for the outer fan rings and 12 bolts for the inner fan rings.

[0046] Step 4: Cut the retaining ring into a groove according to the thickness of the nut;

[0047] Select bolts and nuts with a thickness of 4mm, and cut a 4mm nut-shaped groove at the bolt position on the fixing ring.

[0048] Step 5: Install and secure the retaining ring.

[0049] The embodiments described above merely illustrate specific implementation methods of this application, and while the descriptions are detailed and specific, they should not be construed as limiting the scope of protection of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the technical solution of this application, and these modifications and improvements all fall within the scope of protection of this application.

Claims

1. An umbrella-shaped ring structure for fixing an elastic pad layer on the lower cavity surface of a top cover, characterized in that, include: A rubber elastic pad (1) completely covers the surface of the lower cavity of the top cover; an umbrella-shaped steel structure fixing ring (2) is provided below the elastic pad (1). The fixing ring (2) is composed of a concentric circular skeleton and a radial skeleton, forming a support frame that divides the elastic pad (1) into multiple fan-shaped ring structures; embedded bolts (3) are evenly distributed around the fixing ring (2). The bolts (3) press and fix the elastic pad (1) to the surface of the lower cavity of the top cover (7) by pre-tightening force.

2. The umbrella-shaped ring structure according to claim 1, characterized in that, The concentric circular skeleton of the umbrella-shaped steel structure fixing ring (2) consists of four staggered ring skeletons, with the radius ratio of adjacent ring skeletons being 1.

5.

3. The umbrella-shaped ring structure according to claim 2, characterized in that, The radial skeleton of the umbrella-shaped steel structure fixing ring (2) includes a radial main skeleton (5) arranged at 22.5° angle intervals, and also includes a radial secondary skeleton (6) set between adjacent concentric circular skeletons and at the same angle as the radial main skeleton (5).

4. The umbrella-shaped ring structure according to claim 1, characterized in that, The nut of the embedded bolt (3) adopts a cross-shaped torsion structure. After pre-tightening, the upper surface of the nut is flush with the upper surface of the umbrella-shaped steel structure fixing ring (2).

5. The umbrella-shaped ring structure according to claim 1, characterized in that, The bolts (3) are distributed in an equally spaced ring array along the circumference of the umbrella-shaped steel structure fixing ring (2), and the spacing between adjacent bolts (3) gradually increases along the radial direction.

6. The umbrella-shaped ring structure according to claim 5, characterized in that, The number of bolts (3) located in the outer fan ring area of ​​the umbrella-shaped steel structure fixing ring (2) is 8, and the number of bolts (3) located in the inner fan ring area is 12.

7. The umbrella-shaped ring structure according to claim 1, characterized in that, The fan ring structure has a large free area in the high vibration amplitude region near the crown labyrinth seal (10) of the rotor, and a small free area in the high pressure average region near the crown inlet (9) of the rotor.

8. The umbrella-shaped ring structure according to claim 7, characterized in that, The free area of ​​the fan-ring structure can be adjusted by adjusting the spacing between adjacent concentric circular skeletons and the distribution density of the radial skeleton.

9. The umbrella-shaped ring structure according to claim 1, characterized in that, The contact surface between the umbrella-shaped steel structure fixing ring (2) and the elastic pad (1) forms a flat pressing surface through the pre-tightening force of the bolt (3). The pressing surface, together with the lower cavity surface of the top cover (7) and the upper crown surface of the wheel (8), forms a non-protruding flow channel structure.

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