Fluid static pressure type mechanical sealing device capable of resisting axial vibration and static ring nutation

Abstract

The invention discloses a fluid static pressure type mechanical sealing device capable of resisting axial vibration and static ring nutation, which is mounted on a rotating shaft and comprises a shell, a static ring assembly, a moving ring assembly, an air damping assembly and a universal connecting piece, the static ring assembly and the moving ring assembly are oppositely arranged in a rear cavity in the rear side of the shell in a front-back mode and installed on the rotating shaft in an annular sleeving mode, and an annular cavity communicating with the rear cavity is formed in the front side of the shell. The multiple sets of air damping assemblies are fixed in the annular cavity and movably connected with the front side of the static ring assembly through a plurality of corresponding universal connecting pieces. According to the fluid static pressure type mechanical sealing device capable of resisting axial vibration and static ring nutation, the vibration reduction effect of the two sets of elastic pieces can be brought into full play, the vibration reduction path and the static ring nutation angle can be adjusted by means of the universal assembly device, vibration is effectively reduced or eliminated, the operation stability of the mechanical sealing device is improved, and the service life of the mechanical sealing device is prolonged.

Description

Technical Field

[0001] The invention relates to a fluid static pressure type mechanical sealing device capable of resisting axial vibration and static ring nutation, and relates to the technical field of mechanical sealing. Background Art

[0002] The hydrostatic mechanical seal is a non-contact mechanical seal. It is a mechanical seal device that uses the external pressure flow or the sealed medium itself to produce a hydrostatic effect through the pressure drop of the sealing end face to achieve the sealing function. It has the advantages of low leakage rate, good applicability, and strong stability. It has been widely used in aerospace, chemical, metallurgy, machinery and other industries. During the operation of the mechanical seal, the vibration problem of the sealing ring will cause strong instability to the seal. For the hydrostatic mechanical seal, the main reason for the vibration is the axial vibration and nutation of the floating static ring. Specifically, in the non-contact mechanical seal, the axial vibration or static ring nutation will make the mechanical seal end face gap unable to maintain normally, and have a direct impact on the liquid film thickness distribution, liquid film pressure distribution, contact pressure and sealing leakage. The vibration may also aggravate the wear of the friction end face, reduce the service life of the sealing ring, and then lead to seal failure. In view of this situation, it is necessary to study a hydrostatic mechanical seal device that is resistant to axial vibration and static ring nutation, so that it can effectively reduce vibration within a certain range of vibration frequency or a certain angle of static ring nutation, and increase the stability of the mechanical seal device.

[0003] Based on the established mechanical seal axial and combined vibration model, the researchers explored the influence of the stiffness of the elastic element (spring) in the mechanical seal on the vibration characteristics of the seal. They found that if the spring stiffness is too small, the seal will not be able to return to the equilibrium position within a short period of time under vibration conditions. If the spring stiffness is too large, the single-number fluctuation amplitude of the seal axial displacement, leakage, total liquid film force, etc. will be too large, resulting in seal failure. As a mechanical vibration reduction device widely used in the industrial field, the air spring shock absorber can change the spring stiffness and damping properties by adjusting the air pressure. Under the action of external vibration or impact, it can effectively absorb and disperse energy to achieve the effect of vibration reduction.

[0004] In a general fluid static pressure mechanical seal device, the dynamic ring is fixed to the rotating shaft and rotates with the shaft, while the static ring is floating. Therefore, during the operation of the unit shaft, the floating static ring will produce nutation, forming a certain angle with the dynamic ring along the axial direction, thereby destroying the stable end face liquid film thickness and causing the seal to fail. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a fluid static pressure type mechanical seal device which can effectively reduce or eliminate vibration and improve the running stability and service life of the mechanical seal device and resist axial vibration and static ring nutation.

[0006] In order to solve the above technical problems, the present invention is achieved through the following technical solutions: A fluid static pressure type mechanical sealing device for resisting axial vibration and static ring nutation is installed on a rotating shaft, and includes a shell, a static ring assembly, a dynamic ring assembly, an air shock absorbing assembly, and a universal joint. The rotating shaft is installed in the axial hole in the center of the shell, the static ring assembly and the dynamic ring assembly are arranged in a rear cavity on the rear side of the shell relative to each other front and back, and the uniform ring sleeve is installed on the rotating shaft, an annular cavity connected to the rear cavity is provided inside the front side of the shell, the air shock absorbing assembly is arranged in multiple groups and fixed in the annular cavity and movably connected to the front side of the static ring assembly through a corresponding plurality of universal joints.

[0007] Preferably, the dynamic ring assembly includes a dynamic ring seat and a dynamic ring mounted thereon, and the static ring assembly includes a static ring seat and a static ring mounted thereon, the static ring seat and the dynamic ring seat are arranged with front and rear opposite ring sleeves on the rotating shaft, and the static ring and the dynamic ring are in sliding contact.

[0008] Preferably, the universal connection piece is configured as a universal ball structure or a universal joint structure.

[0009] Preferably, a first elastic member is provided between the air shock absorber assembly and the universal connector, one end of the first elastic member is connected to the tail of the air shock absorber assembly, and the other end is connected to the movable end of the universal connector, and the fixed end of the universal connector is connected to the front side of the static ring seat.

[0010] Preferably, the air shock absorber assembly includes an airbag, a second elastic member, and an air nozzle. A positioning seat is provided in the middle of the bottom of the annular cavity. The front side of the airbag is connected to the bottom of the annular cavity through a screw assembly and is located outside the positioning seat, and the rear side of the airbag is connected to a fixed seat through a screw assembly. An air duct that penetrates the shell is provided on the shell at the corresponding position of the positioning seat. An opening is provided on the front side of the airbag, one end of the air duct is connected to the outside of the shell and an air nozzle is installed, and the other end of the air duct is connected to the opening of the airbag, thereby connecting the airbag with the air duct. The second elastic member is located inside the airbag and one end of it is connected to the positioning seat at the bottom of the annular cavity, and the other end is connected to the fixed seat. The front end of the first elastic member is connected to the rear side of the fixed seat.

[0011] Preferably, the movable end of the universal connector is connected to a movable seat, the front end of the movable seat and the middle of the front and rear ends of the fixed seat are extended to form positioning columns, and the ends of the first elastic member and the second elastic member are respectively connected to the corresponding positioning columns.

[0012] Preferably, the first elastic member and the second elastic member are configured as springs or metal bellows.

[0013] Preferably, the damping force and stiffness of the first elastic member are greater than the damping force and stiffness of the second elastic member.

[0014] Preferably, the first elastic member and the second elastic member always maintain an elastic telescopic deformation state along the axial direction of the rotating shaft during elastic deformation.

[0015] Compared with the prior art, the advantages of the present invention are as follows: the fluid static pressure type mechanical seal device that is resistant to axial vibration and stationary ring nutation can give full play to the vibration reduction effect of the two groups of elastic parts, and can use the universal joint assembly device to adjust the vibration reduction path and the stationary ring nutation angle, and can effectively reduce or eliminate vibration when the rotating shaft is subjected to axial excitation of a certain frequency and the floating stationary ring nutates, thereby improving the operating stability and life of the mechanical seal device. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required to be used in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work. Figure 1 is a side partial cross-sectional view of the present invention; Figure 2 is a side partial cross-sectional view of the air damping assembly of the present invention when connected to the universal connector; Figure 3 This is a schematic diagram of the static ring nutation structure of a general fluid static pressure mechanical seal during operation; Figure 4 It is a schematic diagram of the static ring nutation structure of the present invention when it is running. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention: like Figure 1A fluid static pressure type mechanical sealing device for resisting axial vibration and static ring nutation shown is installed on a rotating shaft 1, and includes a shell 2, a static ring assembly 101, a dynamic ring assembly 102, an air shock absorbing assembly, and a universal connector 3. The rotating shaft is installed in the axial hole in the center of the shell, and the static ring assembly and the dynamic ring assembly are arranged in the rear cavity on the rear side of the shell relative to each other front and back, and the ring sleeve is installed on the rotating shaft. An annular cavity 4 connected to the rear cavity is provided inside the front side of the shell, and the air shock absorbing assembly is arranged in multiple groups and fixed in the annular cavity and movably connected to the front side of the static ring assembly through a corresponding multiple universal connectors. Preferably, the air shock absorbing assembly is distributed in a circular array in the annular cavity, and multiple universal connectors are also distributed and arranged, and the number of both is set to 2. n ( n ≥2) to improve the stability of the overall device. In this embodiment, the dynamic ring assembly includes a dynamic ring seat 5 and a dynamic ring 6 installed thereon, and the dynamic ring and the dynamic ring seat rotate freely with the rotating shaft, and the static ring assembly includes a static ring seat 7 and a static ring 8 installed thereon, and the static ring and the static ring seat are stationary relative to the rotating shaft and the dynamic ring, and the static ring seat and the dynamic ring seat are opposite to each other in the front and back ring sleeves on the rotating shaft, and the static ring and the dynamic ring are in sliding contact, thereby realizing the sliding sealing contact between the static ring and the dynamic ring. In addition, sealing rings 18 are arranged inside the static ring and the static ring seat, and inside the dynamic ring and the dynamic ring seat, which not only achieves a better sealing effect, but also does not affect the free rotation of the rotating shaft relative to the overall sealing device.

[0018] In this embodiment, the universal joint is configured as a universal ball structure or a universal joint structure, such as Figure 1 , Figure 2 As shown, the universal connection piece is configured as a universal ball structure, a ball seat of the universal ball structure is provided on the front side of the stationary ring seat, and the ball head portion of the universal ball is placed in the ball seat and can rotate freely relative to the ball seat.

[0019] In order to improve the supporting effect, a first elastic member 9 is provided between the air shock absorber assembly and the universal connecting member, one end of the first elastic member is connected to the tail of the air shock absorber assembly, and the other end is connected to the ball head end of the universal ball structure, and the fixed end of the ball seat part of the universal ball head is connected to the front side of the static ring seat. Further, the first elastic member is a spring or a metal bellows, and is preferably set to be a first spring in this embodiment. The universal connecting member is a universal ball structure, and the front end of the first spring is connected to the air shock absorber, and the rear end is connected to the ball head part of the universal ball through a movable seat 10. In order to improve the stability of the first spring, in this embodiment, the front side of the movable seat extends forward and forms a positioning column, and the rear end of the first spring is placed on the positioning column, and then the first spring is positioned and fixed. Further, an elastic buffer pad 11 is provided between the rear end of the above-mentioned first spring and the movable seat, so as to improve the buffering effect during the elastic expansion and contraction of the spring.

[0020] Furthermore, the air shock absorbing assembly includes an airbag 12, a second elastic member 13, and an air nozzle 14. A positioning seat 15 is provided in the middle of the bottom of the annular cavity. The front side of the airbag is sealed and connected to the bottom of the annular cavity through a screw assembly and is located outside the positioning seat. The rear side of the airbag is sealed and connected to a fixing seat 16 through a screw assembly. An air passage 17 that penetrates the shell is provided on the shell at the corresponding position of the positioning seat. An opening is provided on the front side of the airbag. One end of the air passage is connected to the outside of the shell where an air nozzle is installed, and the other end of the air passage is connected to the opening of the airbag, thereby connecting the airbag with the air passage. The second elastic component is located inside the airbag and one end of it is connected to the positioning seat at the bottom of the annular cavity, and the other end is connected to the fixing seat. The front end of the first spring is connected to the rear side of the fixing seat. Furthermore, the second elastic member is configured as a spring or a metal bellows. In the present embodiment, it is preferably configured as a second spring, and a positioning groove for the second elastic positioning is provided on the positioning seat. In addition, the front and rear end surfaces of the fixing seat are extended to form positioning columns, so that the ends of the second spring and the first spring are connected to the corresponding positioning columns. In order to further improve the buffering effect, elastic buffer pads are also provided between the positioning seat and the front end of the first spring, between the front end of the fixing seat and the rear end of the first spring, and between the rear end of the fixing seat and the front end of the second spring, so as to further reduce the vibration between them and improve the structural stability.

[0021] In this embodiment, in order to maintain the stability of the device, the damping force and stiffness of the first spring are greater than the damping force and stiffness of the second spring. Therefore, when the equipment is in a non-working state, the second spring plays a major elastic supporting role, thereby increasing the service life of the device.

[0022] In this embodiment, the first spring and the second spring always maintain an axial elastic telescopic deformation state along the rotating shaft during elastic deformation, and no instability occurs. The specific preferred configuration is as follows: , Among them, in formula (1) b 1 is the aspect ratio of the second spring, H 01 is the axial length of the second spring, D 21 is the average diameter of the second spring; in formula (1) b 2 is the aspect ratio of the first spring, H 02 is the axial length of the first spring, D 22 is the average diameter of the first spring.

[0023] In formula (2) and formula (3), F1 is the spring load of the second spring, F cr1 is the critical load of the second spring less than the instability, C B1 is the instability coefficient of the second spring, k 1 is the elastic coefficient of the second spring; F 2 is the spring load of the first spring, F cr2 is the critical load of the first spring less than the instability, C B2 is the instability coefficient of the first spring, k 2 is the elastic coefficient of the first spring.

[0024] Through the above preferred implementation scheme, the first spring and the second spring can effectively only be elastically deformed in the axial direction without instability, thereby improving the stability and firmness of the device.

[0025] As a preferred embodiment, the universal joint may also be configured as a universal joint structure having the same function.

[0026] Therefore, in practical applications, when the vibration of the device is generated in the axial direction, the gas enters the airbag through the air nozzle and the air channel, the internal pressure and bearing capacity of the airbag gradually increase, the airbag begins to deform, and the bearing capacity of the second spring gradually changes and is transmitted to the first spring through the positioning column at the end of the second spring. By adjusting the internal pressure of the airbag, the second spring and the first spring can meet the simplest spring stiffness of the system vibration reduction effect under different working conditions; Figure 3 and Figure 4 As shown, when the bearing force is transmitted to the positioning column at the rear end of the first spring through the first spring, the ball head of the universal ball structure provided on the positioning column at the rear end of the first spring and the ball seat of the universal ball structure provided on the front side of the stationary ring seat are movably matched, and the nutation angle generated by the stationary ring is adjusted by adjusting the inclination angle of the stationary ring assembly, as shown in FIG. Figure 3 , 4As shown, the nutation problem caused by the static ring during the operation of the equipment is reduced or eliminated, and the stability of the mechanical seal during operation is improved. In addition, air enters the airbag through the air nozzle, and the bearing capacity of the second spring is adjusted by changing the internal pressure and bearing capacity of the airbag to meet the stiffness requirements of the damping spring under different working conditions, thereby achieving a better damping effect. The dual-spring damping system design can simultaneously dampen vibrations during the vibration generated by the operation of the device, which improves the response time of the spring, can quickly absorb vibrations, and significantly improves the damping effect.

[0027] It should be emphasized that the above are only preferred embodiments of the present invention and do not limit the present invention in any form. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A hydrostatic mechanical seal device that resists axial vibration and static ring nutation, installed on a rotating shaft, characterized in that: It includes a shell, a static ring assembly, a dynamic ring assembly, an air shock absorbing assembly, and a universal joint. The rotating shaft is installed in the axial hole in the center of the shell. The static ring assembly and the dynamic ring assembly are arranged in the rear cavity on the rear side of the shell relative to each other, and the ring sleeve is installed on the rotating shaft. An annular cavity connected to the rear cavity is provided inside the front side of the shell. The air shock absorbing assembly is arranged in multiple groups and fixed in the annular cavity and movably connected to the front side of the static ring assembly through a corresponding plurality of universal joints.

2. A hydrostatic mechanical seal device for resisting axial vibration and static ring nutation according to claim 1, installed on a rotating shaft, characterized in that: The dynamic ring assembly includes a dynamic ring seat and a dynamic ring installed thereon, and the static ring assembly includes a static ring seat and a static ring installed thereon. The static ring seat and the dynamic ring seat are sleeved on the rotating shaft with front and rear opposite rings, and the static ring and the dynamic ring are in sliding contact with each other.

3. A hydrostatic mechanical seal device for resisting axial vibration and static ring nutation according to claim 2, installed on a rotating shaft, characterized in that: The universal connection piece is configured as a universal ball structure or a universal joint structure.

4. A hydrostatic mechanical seal device for resisting axial vibration and static ring nutation according to claim 2, installed on a rotating shaft, characterized in that: A first elastic member is provided between the air shock absorbing assembly and the universal connector, one end of the first elastic member is connected to the tail of the air shock absorbing assembly, and the other end is connected to the movable end of the universal connector, and the fixed end of the universal connector is connected to the front side of the static ring seat.

5. A hydrostatic mechanical seal device for resisting axial vibration and static ring nutation according to claim 4, installed on a rotating shaft, characterized in that: The air shock absorption assembly includes an airbag, a second elastic member, and an air nozzle. A positioning seat is provided in the middle of the bottom of the annular cavity. The front side of the airbag is connected to the bottom of the annular cavity through a screw assembly and is located outside the positioning seat. The rear side of the airbag is connected to a fixed seat through a screw assembly. An air passage that penetrates the shell is provided on the shell at the corresponding position of the positioning seat. An opening is provided on the front side of the airbag. One end of the air passage is connected to the outside of the shell where an air nozzle is installed, and the other end of the air passage is connected to the opening of the airbag, thereby connecting the airbag with the air passage. The second elastic member is located inside the airbag and one end of it is connected to the positioning seat at the bottom of the annular cavity, and the other end is connected to the fixed seat. The front end of the first elastic member is connected to the rear side of the fixed seat.

6. A hydrostatic mechanical seal device for resisting axial vibration and static ring nutation according to claim 5, installed on a rotating shaft, characterized in that: The movable end of the universal connector is connected to a movable seat, the front end of the movable seat and the middle of the front and rear ends of the fixed seat are extended to form positioning columns, and the ends of the first elastic member and the second elastic member are respectively connected to the corresponding positioning columns.

7. A hydrostatic mechanical seal device for resisting axial vibration and static ring nutation according to claim 6, installed on a rotating shaft, characterized in that: The first elastic member and the second elastic member are configured as springs or metal bellows.

8. A hydrostatic mechanical seal device for resisting axial vibration and static ring nutation according to claim 5, installed on a rotating shaft, characterized in that: The damping force and stiffness of the first elastic member are greater than the damping force and stiffness of the second elastic member.

9. A hydrostatic mechanical seal device for resisting axial vibration and static ring nutation according to claim 5, installed on a rotating shaft, characterized in that: The first elastic member and the second elastic member always maintain an elastic telescopic deformation state along the axial direction of the rotating shaft during elastic deformation.

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