Axial limiting type mechanical seal and assembling method

Abstract

The invention provides an axial limiting type mechanical seal and an assembling method thereof, the axial limiting type mechanical seal comprises a static ring seat and a spring seat, the static ring seat is provided with a large cylinder part, a static ring seat end part, a small cylinder part and a radial extension part which is formed by bending the small cylinder part inwards; the spring seat is provided with a cylinder part, a spring seat end part and a radial extension part which is bent inwards from the cylinder part. The key structure meets the conditions that the distance h1 between the lower end face of the radial extension part of the static ring seat and the upper end face of the radial extension part of the spring seat is larger than or equal to 0.5 mm, and the distance h2 between the lower end face of the static ring seat and the upper end face of the spring seat is larger than or equal to h1 after subtracting the pressing height of the spring. According to the assembling method, synchronous press fitting is achieved through the preassembling assembly composed of the static ring base, the corrugated pipe, the spring and the spring base and the axial force driving extension part in an abutting mode, and the two modes of press fitting in advance or loading after press fitting of the static ring are supported. The spring seat is effectively prevented from vibrating and rebounding, rigid collision of a friction pair is eliminated, the problems of unreliable axial positioning of the spring seat and rigid collision in operation are solved, and the assembly efficiency is remarkably improved.

Description

Technical Field

[0001] The present invention relates to the field of applied technology applied to the design of end face mechanical seal assembly structure, and in particular to an axially limited mechanical seal and an assembly method thereof. Background Art

[0002] Mechanical seals are key components in rotating equipment, such as pumps and compressors. Their core function is to seal media through the tight fit of sealing rings, preventing fluid leakage and reducing wear on friction pairs. In the field of end-face mechanical seals, the bellows lower end radial compression seal is widely used due to its compactness and adaptability. Its assembly process and the reliability of the spring seat positioning directly affect sealing performance and equipment life.

[0003] In the prior art, the positioning of the spring seat for radial compression sealing at the lower end of the bellows mostly relies on elastic force or interference fit. For example, some solutions limit the displacement of the spring seat by the axial elastic force of the spring, but the tiny gap between the stationary ring seat and the inner diameter of the bellows seat causes the flexible deformation of the rubber bellows to be easily caused during the tooling press-fitting process, resulting in axial positioning deviation of the spring seat; other solutions use rubber interference fit to achieve axial fixation, but if the inner cylinder of the bellows seat has a taper or excessive form and position tolerances, the spring seat is prone to rebound due to rubber tensile force or mechanical vibration during assembly or operation, requiring strict processing precision and significantly increasing manufacturing costs. In addition, in order to meet high coaxiality requirements, existing tooling designs often require ultra-thin structures, resulting in insufficient strength and difficulty in adapting to automated assembly.

[0004] Regarding the radial compression sealing structure, the existing technology still has the following deficiencies:

[0005] 1. Complex assembly process: The rubber bellows is easily deformed during press-fitting, resulting in misalignment of the spring seat.

[0006] 2. Weak anti-vibration ability: The movement or vibration of the pump shaft during operation can easily cause the spring seat to rebound and damage the friction pair.

[0007] 3. Strict tolerance requirements: When relying on interference fit, high-precision processing is required, which significantly increases costs.

[0008] 4. Poor tooling adaptability: Traditional tooling design has difficulty balancing strength and coaxiality, which restricts automated production.

[0009] The invention patent application number US7870654B2 discloses a mechanical sealing device. Although it improves the stick-slip noise problem of the sealing surface by controlling the rotational clearance between the sealing ring groove and the cantilever beam, its technical focus is on dynamic friction stability and does not involve the optimization of the positioning reliability of the spring seat at the lower end of the bellows.

[0010] Therefore, there is an urgent need for an optimized solution for the radial compression seal at the lower end of the bellows. Through structural innovation and coordinated dimensional control, the reliable positioning of the spring seat can be achieved, the assembly process can be simplified, and the operational stability can be improved, thus breaking through the existing technical bottleneck. Summary of the Invention

[0011] In view of this, an object of the present invention is to provide an axially limited mechanical seal and an assembly method, which can achieve reliable positioning of the spring seat in the mechanical seal, simplify the assembly process and improve the operating stability of the device.

[0012] An axially limited mechanical seal comprises: a transmission seat, an auxiliary sealing ring, a rotating ring, a stationary ring, a stationary ring seat, a bellows, a spring, a spring seat and a bellows seat;

[0013] The stationary ring seat comprises a large cylindrical portion, an end portion of the stationary ring seat, a small cylindrical portion, and a radial extension portion of the stationary ring seat formed by bending the small cylindrical portion inward; the stationary ring, the upper cylindrical portion of the bellows, and the upper end portion of the bellows are assembled in the internal space formed by the large cylindrical portion, the end portion of the stationary ring seat, the small cylindrical portion, and the radial extension portion of the stationary ring seat;

[0014] The spring seat comprises a spring seat cylinder, a spring seat end, and a spring seat radial extension formed by inward bending of the spring seat cylinder; the bellows seat cylinder and the bellows lower cylinder are assembled in the internal space formed by the spring seat cylinder, the spring seat end, and the spring seat radial extension;

[0015] The spatial distance between the lower end surface of the stationary ring seat and the upper end surface of the spring seat is h2, which is used to provide assembly space for the spring;

[0016] The spatial distance h1 between the lower end surface of the radially extending portion of the stationary ring seat and the upper end surface of the radially extending portion of the spring seat is not less than 0.5 mm;

[0017] The spatial distance h2 between the lower end surface of the stationary ring seat end and the upper end surface of the spring seat end, minus the height of the spring when compressed, is not less than h1;

[0018] The upper cylinder portion of the bellows is assembled in the inner space formed by the large cylinder portion of the stationary ring seat, and the lower cylinder portion of the bellows is assembled in the inner space formed by the cylinder portion of the spring seat.

[0019] Furthermore, the inward bending angle of the radially extending portion of the stationary ring seat is 90°, and the inward bending angle of the radially extending portion of the spring seat is also 90°.

[0020] Furthermore, the outer diameter of the spring seat end portion is equal to or greater than the outer diameter of the spring to which it is attached, and its radial extension length is adapted to the mean diameter of the spring.

[0021] Furthermore, a radial gap is formed between the inner hole of the large cylindrical portion of the stationary ring seat and the outer circle of the stationary ring to achieve radial compression sealing of the upper cylindrical portion of the bellows.

[0022] Furthermore, a radial gap is formed between the inner hole of the spring seat cylinder and the outer circle of the bellows seat cylinder to achieve radial compression sealing of the lower cylinder of the bellows.

[0023] In another aspect of the present invention, a method for assembling an axially limited mechanical seal is provided, comprising the following steps:

[0024] S1. Assemble the upper tube of the bellows into the internal space of the large tube of the stationary ring seat;

[0025] S2. The spring is assembled on the outer circle of the small cylindrical portion of the stationary ring seat, and one end thereof rests against the lower end surface of the stationary ring seat end;

[0026] S3. The spring seat is assembled in the inner hole of the spring, and the upper end surface of the spring seat end is against the other end of the spring to form a pre-assembled assembly;

[0027] S4. Apply axial force to the stationary ring seat to drive the radial extension of the stationary ring seat against the radial extension of the spring seat, and synchronously move the spring seat to the target position so that the end of the spring seat presses the lower end of the bellows against the upper end surface of the bellows seat;

[0028] S5. After completing the static side assembly, assemble the dynamic side components;

[0029] The stationary ring can be assembled in any of the following ways:

[0030] Method 1: After step S4, the stationary ring is installed into the inner hole of the upper cylinder of the bellows;

[0031] Method 2: In step S1 , the stationary ring is pre-installed into the inner hole of the upper cylinder of the bellows.

[0032] Furthermore, in step S4, the moving distance of the stationary ring seat is limited by the tooling to ensure that after assembly:

[0033] The spatial distance h1 between the radial extension of the stationary ring seat and the radial extension of the spring seat is ≥ 0.5 mm;

[0034] The spatial distance h2 between the end of the stationary ring seat and the end of the spring seat minus the compressed height of the spring is ≥ h1.

[0035] Furthermore, it is characterized in that: the pre-assembled component formed in step S3 is any of the following:

[0036] Composition 1: stationary ring seat, bellows, spring, spring seat;

[0037] Composition 2: stationary ring, stationary ring seat, bellows, spring, and spring seat.

[0038] Furthermore, in step S1, the upper cylinder portion of the bellows and the large cylinder portion of the stationary ring seat are compressed and sealed via a radial gap, wherein the radial gap is formed by the size difference between the inner hole of the stationary ring seat and the outer circle of the stationary ring.

[0039] Furthermore, in step S3, the synchronous movement of the spring seat is guided by the radial gap between its cylindrical portion and the cylindrical portion of the bellows seat, and the radial gap is formed by the size difference between the inner hole of the spring seat and the outer circle of the bellows seat.

[0040] The present invention has the following advantages:

[0041] 1. The axial rebound problem of the spring seat caused by vibration or rubber deformation is solved by designing the bending structure of the radial extension portion (54) of the stationary ring seat and the radial extension portion (83) of the spring seat in combination with the non-contact space of h1≥0.5mm.

[0042] 2. The h1 spatial distance provides a buffer margin for pump shaft movement and assembly errors, avoids rigid collision damage between the stationary ring seat and the spring seat, and provides damage protection for the sealing surface friction pair.

[0043] 3. The design of h2-spring compression height ≥ h1 ensures that the spring is always in the effective compression range, preventing elastic force attenuation or overload caused by working height deviation, and optimizing the stability of the spring.

[0044] 4. Through the pre-assembled component design, it supports two assembly modes with or without stationary rings, adapts to the assembly of stationary rings with different materials and processes, and significantly improves assembly efficiency.

[0045] 5. Synchronous axial movement is achieved by tightening the radial extension of the stationary ring seat against the extension of the spring seat, replacing the traditional step-by-step press-fitting and avoiding positioning misalignment caused by bellows deformation. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 This is the structural diagram of the axial limit type mechanical seal;

[0047] Figure 2 This is a component diagram of the assembly method described in Example 2;

[0048] Figure 3 This is a component diagram of the assembly method described in Example 3;

[0049] In the figure: 1. Transmission seat; 2. Auxiliary sealing ring; 3. Rotating ring; 4. Stationary ring; 41. Outer circle of stationary ring; 5. Stationary ring seat; 51. Large cylinder of stationary ring seat; 52. Inner hole of large cylinder of stationary ring seat; 53. End of stationary ring; 54. Radial extension of stationary ring seat; 55. Small cylinder of stationary ring seat; 6. Bellows; 61. Upper cylinder of bellows; 62. Inner hole of upper cylinder of bellows; 64. Lower end of bellows; 67. Lower cylinder of bellows; 68. Upper end of bellows; 7. Spring; 8. Spring seat; 81. Spring seat cylinder; 82. End of spring seat; 83. Radial extension of spring seat; 84. Inner hole of cylinder of spring seat; 9. Bellows seat; 91. Bottom of bellows seat; 92. Bellows seat cylinder; 93. Outer circle of bellows seat cylinder. DETAILED DESCRIPTION

[0050] In order to more clearly understand the above-mentioned objectives, features and advantages of the present disclosure, the solutions of the present invention will be further described below. It should be noted that the embodiments of the present invention and the features therein can be combined with each other without conflict.

[0051] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein; it is obvious that the embodiments in the specification are only part of the embodiments of the present invention, rather than all the embodiments.

[0052] To facilitate understanding of the present invention, the present invention will be described more fully below with reference to the accompanying drawings. The drawings illustrate embodiments of the present invention. However, the present invention may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive overview of the present invention.

[0053] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention pertains. The terms used in the specification are only for describing specific embodiments and are not intended to limit the present application.

[0054] Example 1

[0055] like Figure 1 As shown, this embodiment provides an axially limited mechanical seal, comprising: a transmission seat 1, an auxiliary sealing ring 2, a rotating ring 3, a stationary ring 4, a stationary ring seat 5, a bellows 6, a spring 7, a spring seat 8 and a bellows seat 9;

[0056] The stationary ring seat 5 includes a large cylindrical portion 51, a stationary ring seat end portion 53, a small cylindrical portion 55, and a stationary ring seat radial extension portion 54 formed by bending the small cylindrical portion 55 inward; the stationary ring 4, the bellows upper cylindrical portion 61, and the bellows upper end portion 68 are assembled in the internal space formed by the large cylindrical portion 51, the stationary ring seat end portion 53, the small cylindrical portion 55, and the stationary ring seat radial extension portion 54;

[0057] The spring seat 8 includes a spring seat cylinder 81, a spring seat end 82, and a spring seat radial extension 83 formed by bending the spring seat cylinder 81 inward; the bellows seat cylinder 92 and the bellows lower cylinder 67 are assembled in the internal space formed by the spring seat cylinder 81, the spring seat end 82, and the spring seat radial extension 83;

[0058] The spatial distance between the lower end surface of the stationary ring seat end 53 and the upper end surface of the spring seat end 82 is h2, which is used to provide an assembly space for the spring 7;

[0059] The spatial distance h1 between the lower end surface of the stationary ring seat radial extension portion 54 and the upper end surface of the spring seat radial extension portion 83 is not less than 0.5 mm;

[0060] The spatial distance h2 between the lower end surface of the stationary ring seat end 53 and the upper end surface of the spring seat end 82 is not less than h1 after deducting the height of the spring 7 when compressed;

[0061] Furthermore, the inward bending angle of the radial extension portion 54 of the stationary ring seat is 90°, and the inward bending angle of the radial extension portion 83 of the spring seat is also 90°.

[0062] Furthermore, the outer diameter of the spring seat end portion 82 is equal to or greater than the outer diameter of the spring 7 , and its radial extension length is adapted to the middle diameter of the spring 7 .

[0063] Furthermore, the inner hole 52 of the large cylindrical portion 51 of the stationary ring seat and the outer circle 41 of the stationary ring 4 form a radial gap for achieving radial compression sealing of the upper cylindrical portion 61 of the bellows.

[0064] Furthermore, the inner hole 84 of the spring seat cylinder 81 and the outer circle 93 of the bellows seat cylinder 92 form a radial gap for achieving radial compression sealing of the bellows lower cylinder 67 .

[0065] Example 2

[0066] Based on the above embodiment of the axially limited mechanical seal, this embodiment also provides a corresponding assembly method embodiment. An assembly method of the axially limited mechanical seal includes the following steps:

[0067] After the upper end portion 68 of the bellows is assembled with the stationary ring seat 5 , the spring 7 is assembled on the outer circle of the small cylindrical portion 55 of the stationary ring seat and abuts against the lower end of the end portion 53 of the stationary ring seat.

[0068] like Figure 2 As shown, the spring seat 8 is assembled in the inner hole of the spring and the end face is pressed against the other end of the spring. In this way, the stationary ring seat 5, the bellows 6, the spring 7 and the spring seat 8 constitute an assembly.

[0069] An axial force is applied to the large cylindrical portion 51 of the stationary ring seat. When the stationary ring seat 5 moves a certain distance, the radial extension portion 54 of the stationary ring seat is pressed against the radial extension portion 83 of the spring seat, so that the spring seat 8 moves axially synchronously. After the moving distance is limited by the tooling or a suitable axial force is applied, the spring seat end portion 82 presses the bellows end portion 64 against the upper end surface of the bellows seat bottom portion 91.

[0070] Finally, the stationary ring 4 is installed in the inner hole 62 of the upper cylinder of the bellows. In this way, the static side assembly of the mechanical seal device is realized, and then the dynamic side is assembled into the static side in the current general manner.

[0071] In this embodiment, the stationary ring 4 is installed into the inner bore 62 of the upper cylindrical portion of the bellows in the final step. This effectively prevents damage to the stationary ring 4 caused by axial forces during the press-fit process. When the stationary ring is made of brittle materials such as ceramic and silicon carbide, the method described in this embodiment can be used for assembly to avoid damage to the stationary ring 4 caused by press-fit forces.

[0072] Example 3

[0073] This embodiment also provides another assembly method embodiment, including the following steps:

[0074] After the upper end 68 of the bellows is assembled with the stationary ring seat 5, the stationary ring 4 is installed into the inner hole 62 of the upper end of the bellows, and the spring 7 is assembled on the outer circle of the small cylindrical portion 55 of the stationary ring seat and abuts against the lower end of the stationary ring seat end 53.

[0075] like Figure 3 As shown, the spring seat 8 is assembled in the inner hole of the spring 7 and the end face thereof is pressed against the other end of the spring. In this way, the stationary ring 4, the stationary ring seat 5, the bellows 6, the spring 7 and the spring seat 8 form an assembly.

[0076] An axial force is applied to the large cylindrical portion 51 of the stationary ring seat. When the stationary ring seat 5 moves a certain distance, the radial extension portion 54 of the stationary ring seat is pressed against the radial extension portion 83 of the spring seat, so that the spring seat 8 moves axially synchronously. After the moving distance is limited by the tooling or a suitable axial force is applied, the end of the spring seat presses the end 64 of the bellows against the upper end surface of the bottom 91 of the bellows seat.

[0077] Finally, assemble the moving side into the static side in the current general way to complete the assembly.

[0078] In this embodiment, the stationary ring 4 is initially installed into the inner bore 62 of the upper cylindrical portion of the bellows. This allows the stationary side assembly, including the stationary ring, to be formed in one step, reducing subsequent steps and improving assembly efficiency. If the stationary ring is made of metal or composite material, the method described in this embodiment can be used for assembly, with integrated pre-assembly preferred for improved assembly efficiency.

[0079] Thus far, various embodiments of the present invention have been described in detail. To avoid obscuring the concept of the present invention, some details well known in the art have not been described. Based on the above description, those skilled in the art can fully understand how to implement the technical solutions disclosed herein.

[0080] Although some specific embodiments of the present invention have been described in detail through examples, those skilled in the art will understand that the above examples are for illustration only and are not intended to limit the scope of the present invention. Those skilled in the art will understand that the above embodiments may be modified or some technical features may be replaced with equivalents without departing from the scope and spirit of the present invention. The scope of the present invention is defined by the appended claims.

Claims

1. An axially limited mechanical seal, characterized in that: include: Transmission seat (1), auxiliary sealing ring (2), rotating ring (3), stationary ring (4), stationary ring seat (5), bellows (6), spring (7), spring seat (8) and bellows seat (9); The stationary ring seat (5) comprises a large cylindrical portion (51), a stationary ring seat end portion (53), a small cylindrical portion (55), and a stationary ring seat radial extension portion (54) formed by bending the small cylindrical portion (55) inward; the stationary ring (4), the bellows upper cylindrical portion (61), and the bellows upper end portion (68) are assembled in an internal space formed by the large cylindrical portion (51), the stationary ring seat end portion (53), the small cylindrical portion (55), and the stationary ring seat radial extension portion (54); The spring seat (8) includes a spring seat cylinder (81), a spring seat end (82), and a spring seat radial extension (83) formed by bending the spring seat cylinder (81) inward; the bellows cylinder (92) and the bellows lower cylinder (67) are assembled in the internal space formed by the spring seat cylinder (81), the spring seat end (82), and the spring seat radial extension (83); The spatial distance between the lower end surface of the stationary ring seat end (53) and the upper end surface of the spring seat end (82) is h2, which is used to provide an assembly space for the spring (7); The spatial distance h1 between the lower end surface of the radial extension portion (54) of the stationary ring seat and the upper end surface of the radial extension portion (83) of the spring seat is not less than 0.5 mm; The spatial distance h2 between the lower end surface of the stationary ring seat end (53) and the upper end surface of the spring seat end (82) is not less than h1 after deducting the height of the spring (7) when compressed.

2. The axially limited mechanical seal according to claim 1, characterized in that: The inward bending angle of the radial extension portion (54) of the stationary ring seat is 90°, and the inward bending angle of the radial extension portion (83) of the spring seat is 90°.

3. The axially limited mechanical seal according to claim 1, characterized in that: The outer diameter of the spring seat end portion (82) is equal to or greater than the outer diameter of the corresponding spring (7), and its radial extension length is adapted to the middle diameter of the spring (7).

4. The axially limited mechanical seal according to claim 1, characterized in that: The inner hole (52) of the large cylindrical portion (51) of the stationary ring seat and the outer circle (41) of the stationary ring (4) form a radial gap for achieving radial compression sealing of the upper cylindrical portion (61) of the bellows.

5. The axially limited mechanical seal according to claim 1, characterized in that: The inner hole (84) of the spring seat cylinder (81) and the outer circle (93) of the bellows seat cylinder (92) form a radial gap for achieving radial compression sealing of the bellows lower cylinder (67).

6. A method for assembling an axially limited mechanical seal, characterized in that: The following steps are involved: S1. The upper cylindrical portion (61) of the bellows (6) is assembled into the internal space of the large cylindrical portion (51) of the stationary ring seat (5); S2. The spring (7) is assembled on the outer circle of the small cylindrical portion (55) of the stationary ring seat, and one end thereof is abutted against the lower end surface of the stationary ring seat end portion (53); S3. The spring seat (8) is assembled in the inner hole of the spring (7), and the upper end surface of the spring seat end (82) is pressed against the other end of the spring (7) to form a preassembled assembly; S4. Applying axial force to the stationary ring seat (5), driving the radial extension portion (54) of the stationary ring seat to press against the radial extension portion (83) of the spring seat, and synchronously moving the spring seat (8) to the target position, so that the end portion (82) of the spring seat presses the lower end portion (64) of the bellows against the upper end surface of the bellows seat (9); S5. After completing the static side assembly, assemble the dynamic side components; The stationary ring (4) is assembled in any of the following ways: Method 1: After step S4, the stationary ring (4) is installed into the inner hole (62) of the upper cylinder (61) of the bellows; Method 2: In step S1, the stationary ring (4) is pre-installed into the inner hole (62) of the upper cylinder (61) of the bellows.

7. The assembly method according to claim 6, characterized in that: In step S4, the moving distance of the stationary ring seat (5) is limited by the tooling to ensure that after assembly: The spatial distance h1 between the radial extension portion (54) of the stationary ring seat and the radial extension portion (83) of the spring seat is ≥0.5 mm; The spatial distance h2 between the end of the stationary ring seat (53) and the end of the spring seat (82) minus the spring compression height is greater than or equal to h1.

8. The assembly method according to claim 6, characterized in that: The pre-assembled component formed in step S3 is any of the following: Composition 1: stationary ring seat (5), bellows (6), spring (7), spring seat (8); Composition 2: a stationary ring (4), a stationary ring seat (5), a bellows (6), a spring (7), and a spring seat (8).

9. The assembly method according to claim 6, wherein: In step S1, the upper cylinder portion (61) of the bellows and the large cylinder portion (51) of the stationary ring seat are compressed and sealed through a radial gap, and the radial gap is formed by the size difference between the inner hole (52) of the stationary ring seat and the outer circle (41) of the stationary ring.

10. The assembly method according to claim 6, wherein: In step S3, the synchronous movement of the spring seat (8) is guided by the radial gap between its cylinder (81) and the bellows seat cylinder (92), and the radial gap is formed by the size difference between the spring seat inner hole (84) and the bellows seat outer circle (93).

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