Back pressure area adjustable and opening controllable type floating ring for non-contact mechanical seal

Abstract

The application discloses an adjustable back pressure area and controllable opening type floating ring for non-contact mechanical sealing, which comprises a fan-shaped plate sliding block, a back cover, a driving gear shaft and a central transmission body. The application is different from any existing controllable mechanical sealing floating ring. The principle of the application is to change the floating ring area through pure mechanical transmission, set a maximum value for the floating ring composed of the fan-shaped area, apply corresponding speed to the driving gear shaft according to the transmission ratio between the transmission mechanisms and the actual situation, and realize the adjustment of the closing force. When the working condition is high pressure, the application can realize quick opening, and lay a solid foundation for subsequent stable operation. Under the premise that the sealing working environment is determined, the application has the characteristics of easy opening, high controllability, stable transmission and the like, and can effectively control the closing force. In addition, the application can be flexibly adapted to the change of the dry gas sealing working environment.

Description

Technical Field

[0001] This invention belongs to the field of mechanical seal technology, specifically relating to a floating ring with adjustable back pressure area and controllable opening for non-contact mechanical seals. Background Technology

[0002] Compared to traditional contact seals, which are prone to leakage, contamination, short lifespan, and low economic efficiency, dry gas seals offer advantages such as long service life, stability, reliability, low power consumption, and environmental friendliness, leading to their widespread application in related fields. The grooved dry gas seal's rotating ring face is generally divided into two functional areas: an outer area and an inner area. When the rotating ring, with a hydrodynamic groove (groove depth 2.5–10 µm) on its outer side, rotates, the hydrodynamic groove pumps high-pressure lubricating gas from the outer diameter side into the space between the sealing end faces. The gas is compressed in the grooved outer area, meaning the gas film pressure gradually increases from the outer diameter to the groove diameter, forming a local high-pressure zone at the groove root, generating a hydrodynamic effect. Under the balance between the gas film force and the back pressure closing force of the floating ring within the sealing end face gap, a stable gas film of a certain thickness is formed.

[0003] According to the working principle of dry gas seals, the force balance of the floating ring always exists during the operation of the dry gas seal. The opening force is determined by the gas film pressure distribution within the sealing gap, while the closing force is related to the inlet pressure, balance radius, and spring specific pressure. Dry gas seal design is generally based on the operating conditions of its supporting host machine. In the current environment where dry gas seal applications tend to be high-pressure environments, high inlet pressure significantly increases the back pressure force of the floating ring, thus posing a challenge to the opening of the dry gas seal. Rapid opening of the dry gas seal lays a solid foundation for its subsequent stable operation. If opening is not smooth, i.e., the sealing ring remains in contact for a long time, it will lead to wear on the end face of the sealing ring or excessive temperature rise on the end face. Therefore, given a fixed sealing operating environment, to achieve the easy-to-open characteristic of the dry gas seal, the closing force can be adjusted, requiring the dry gas seal to possess the characteristic of "controllability."

[0004] Chinese patent CN104179975A proposes a device that uses an electromagnet to apply current and a sensor to dynamically monitor it, thereby forming an active control of the closing force. However, this requires auxiliary devices such as electromagnets, making it quite complex. Furthermore, it does not specify whether AC or DC power is used. If an AC electromagnet is used, its attraction force relies on the DC component of the superposition of the magnetic forces of two alternating magnetic fields formed by the magnetic rings to do work, resulting in low efficiency, large core volume, and high coil energy consumption. At the same time, it generates excessive heat during long-term operation, disrupting the sealing effect. On the other hand, if DC power is used, the cost increases dramatically, making it uneconomical.

[0005] Chinese patent CN102128272A proposes a mechanical seal device with controllable closing force. By adjusting the leakage of the floating ring, a comb-tooth seal is formed, achieving a throttling effect and thus regulating the closing force. To achieve this goal, the gap between the comb-tooth seal and the outer edge of the stationary ring must be strictly controlled. However, under high-pressure and high-speed conditions, the radial runout of the sealing ring will affect this gap, limiting the effectiveness of the throttling effect.

[0006] Chinese patent CN104896104A discloses a gas-lubricated mechanical seal device with online adjustable closing force. Its core idea is to design a piston structure after the stationary ring. By adjusting the gas supply pressure, the piston compresses the spring, thereby changing the spring compression to adjust the closing force. This solution is feasible under low-pressure conditions, but in high-pressure, heavy-load environments, the spring force is negligible compared to the back pressure of the stationary ring.

[0007] Therefore, it is essential to develop a floating ring with adjustable back pressure area and controllable opening for non-contact mechanical seals that can solve the above problems. Summary of the Invention

[0008] The purpose of this invention is to overcome the problem of overly complex sealing structures or control systems in existing dry gas sealing technologies, and to provide a simple floating ring with adjustable back pressure area and controllable opening for non-contact mechanical seals. This invention uses pure mechanical transmission, requiring only the application of the required speed at the drive gear shaft, making it simple to operate, safe and reliable, and with strong anti-interference capabilities. Secondly, the machinery involved in this invention is easy to mass-produce and readily applicable on a large scale. Finally, if a new transmission relationship is required, the corresponding links in the transmission relationship can be replaced as needed, which greatly reduces economic costs.

[0009] The objective of this invention is achieved by including a sector-shaped plate slider, a rear cover, a drive gear shaft, and a central transmission body;

[0010] The sector-shaped plate slider includes a sector-shaped plate body and a slider disposed inside the sector-shaped plate body, with teeth on the bottom surface of the slider;

[0011] The rear cover is a circular cover with a circular wall surface at the edge and a through hole in the center. A circular hole is opened on the inner surface of the rear cover. The circular hole is not a through hole and is close to the through hole. A first O-ring is provided at the top of the circular wall surface.

[0012] The central transmission body includes a disc and an internal meshing gear. The disc has a hole in the center and a plane thread around the hole on the top surface of the disc. The hole is connected to the top edge of the cylindrical wall. The internal meshing gear is fixed to the bottom edge of the cylindrical wall. The inner diameter of the internal meshing gear is larger than the diameter of the through hole.

[0013] There are three sector-shaped sliders distributed along the circumference, and the sector-shaped plates are all at 120°. The bottom surface of the sector-shaped plate body is in close contact with the top surface of the disk, and the teeth on the bottom surface of the slider slide in contact with the planar thread on the top surface of the disk. A second O-ring is provided around the planar thread, and the second O-ring is in close contact with the bottom surface of the sector-shaped plate body. The rear cover is placed on the bottom surface of the central transmission body, and the top of the circumferential wall is in contact with the edge of the disk. The first O-ring is located between the two, and the circular hole protrudes from the inside of the internal meshing gear. The cylindrical key at the end of the drive gear shaft is embedded in the circular hole, and the gear of the drive gear shaft meshes with the internal meshing gear.

[0014] The beneficial effects of this invention are as follows: Unlike any existing controllable mechanical seal using a floating ring, this invention changes the area of ​​the floating ring through pure mechanical transmission. A maximum value is set for the floating ring, which is composed of a sector-shaped area. An appropriate speed is applied to the drive gear shaft based on the transmission ratio between the transmission mechanisms and the actual situation, thereby adjusting the closing force. Under high-pressure conditions, this invention enables rapid opening, laying a solid foundation for subsequent stable operation. Given a defined sealing environment, it features easy opening, high controllability, and stable transmission, effectively regulating the closing force. Furthermore, this invention can flexibly adapt to changes in dry gas sealing environments. Attached Figure Description

[0015] Figure 1 This is a three-dimensional structural diagram of the present invention;

[0016] Figure 2 This is a three-dimensional structural diagram of the present invention with one sector-shaped slider removed;

[0017] Figure 3 A schematic diagram of the top surface of the central transmission body;

[0018] Figure 4 A three-dimensional structural diagram of the bottom surface of the central transmission body;

[0019] Figure 5 This is a schematic diagram of the structure of the top surface of the back cover;

[0020] Figure 6 This is a schematic diagram of the three-dimensional structure of the bottom surface of the back cover;

[0021] Figure 7 A three-dimensional structural diagram of the drive gear shaft;

[0022] Figure 8 This is a schematic diagram of the three-dimensional structure of the bottom surface of the sector-shaped plate slider;

[0023] Figure 9 This is a schematic diagram of the overall assembly structure of the present invention in use.

[0024] In the figure: 1-sector plate slider, 101-sector plate body, 102-slider, 2-rear cover, 201-circumferential wall surface, 202-through hole, 203-round hole, 3-drive gear shaft, 4-central transmission body, 401-disc, 402-internal meshing gear, 403-hole, 404-planar thread, 405-cylindrical wall, 5-first O-ring, 6-second O-ring, 7-floating ring of this invention, 8-cavity, 9-air inlet, 10-shoulder sleeve I, 11-moving ring, 12-sealing ring, 13-pin, 14-shaft, 15-spring seat, 16-spring, 17-push ring, 18-shoulder sleeve II. Detailed Implementation

[0025] The present invention will be further described below with reference to the accompanying drawings, but this is not intended to limit the present invention in any way. Any modifications or substitutions made based on the teachings of the present invention shall fall within the protection scope of the present invention.

[0026] As attached Figures 1-9 The invention shown includes a sector-shaped plate slider 1, a rear cover 2, a drive gear shaft 3, and a central transmission body 4.

[0027] The sector plate slider 1 includes a sector plate body 101 and a slider 102 disposed inside the sector plate body 101, and the bottom surface of the slider 102 is toothed.

[0028] The rear cover 2 is a circular cover with a circumferential wall 201 at the edge and a through hole 202 at the center. A circular hole 203 is opened on the inner surface of the rear cover 2. The circular hole 203 is not a through hole and is close to the through hole 202. A first O-ring 5 is provided at the top of the circumferential wall 201 to prevent high-pressure gas from entering.

[0029] The central transmission body 4 includes a disk 401 and an internal meshing gear 402. The disk 401 has a hole 403 in the center and a plane thread 404 around the hole 403 on the top surface of the disk 401. The hole 403 is connected to the top edge of the cylindrical wall 405. The internal meshing gear 402 is fixed to the bottom edge of the cylindrical wall 405. The inner diameter of the internal meshing gear 402 is larger than the diameter of the through hole 202 to ensure that it completely covers the drive gear shaft 3 and prevents the drive gear shaft 3 from colliding with the bushing II 18.

[0030] The aforementioned central transmission body 4 is an integral unit composed of three parts: a disc 401, an internal meshing gear 402, and a cylindrical wall 405. The internal meshing gear 402 is responsible for transmitting the power provided by the drive gear shaft 3, the cylindrical wall 405 provides support, and the planar thread 404 of the disc 401 engages with the teeth of the slider 102.

[0031] There are three sector-shaped sliders 1, distributed along the circumference, and each sector-shaped body 101 is at a 120° angle. The bottom surface of the sector-shaped body 101 is in close contact with the top surface of the disk 401, and the teeth on the bottom surface of the slider 102 slide in contact with the planar thread 404 on the top surface of the disk 401. The movement of the three sector-shaped sliders 1 together achieves the purpose of variable area. The diameter of the inner circle of the sector-shaped body 101 determines its lower limit of movement. A second O-ring 6 is provided around the planar thread 404, and the second O-ring 6 is in close contact with the sector-shaped body. The bottom surface of 101 prevents high-pressure gas from entering; the rear cover 2 covers the bottom surface of the central transmission body 4, and the top of the circumferential wall 201 contacts the edge of the disc 401, with the first O-ring 5 located between them, and the circular hole 203 protruding from the inside of the internal meshing gear 402; the rear cover 2 does not rotate with the central transmission body 4; the cylindrical key at the end of the drive gear shaft 3 is embedded in the circular hole 203, and the gear of the drive gear shaft 3 meshes with the internal meshing gear 402, with the cylindrical key and the circular hole 203 serving a positioning function.

[0032] The fan-shaped plate body 101 and the slider 102 are integrally formed.

[0033] The other end of the drive gear shaft 3 is connected to a power device, which is used to drive the drive gear shaft 3 to rotate; during assembly, the shaft of the drive gear shaft 3 can pass through the bushing II18.

[0034] The first O-ring and the second O-ring serve a sealing function. The first O-ring is installed on the top of the circumferential wall 201. Specifically, a groove is provided on the top of the circumferential wall 201 so that the first O-ring can be embedded and fixed in the groove. The second O-ring is installed on the disc 401 on the periphery of the planar thread 404. Specifically, a groove is provided on the disc 401 so that the second O-ring can be embedded and fixed in the groove.

[0035] The rear cover 2 and the central transmission body 4 are connected by an inlay structure. The inlay structure typically uses graphite material as the non-metallic sealing ring plate and metal materials such as S07 and 4J31 as the metal ring seat. The non-metallic sealing ring and the metal ring seat are tightly bonded together by the radial deformation force generated when the two are interfered with. This structure can not only improve the mechanical properties of the sealing ring made of softer materials, but also save the amount of precious metals used. Depending on the application of the mechanical seal, the use of an inlay structure for the sealing ring can effectively improve the rigidity and strength of the sealing ring, reduce production costs, and the sealing ring with this structure is easy to process and manufacture.

[0036] The working principle and process of this invention: The principle of this invention is to control the sealing opening capability by changing the magnitude of the closing force on the floating ring; the specific process of changing the back pressure area of ​​the floating ring is to first set a maximum value (maximum floating ring area) for the floating ring area composed of the sector area formed by the three sector plate sliders 1, and then through the drive gear shaft 3 that provides power, and the central transmission body 4 with internal meshing gear 402 that meshes with it, there is a specific proportional relationship between the planar thread 404 on the back ring side of the central transmission body 4 and the sector plate slider 1. To determine the transmission ratio between the drive gear shaft 3 and the internal meshing gear 402, the number of rotations of the planar thread 404 and the movement distance of the slider 102 are proportional. When V3 is given, the movement distance of the slider can be calculated. Then, based on the movement distance of the slider 102, the area of ​​the sector plate body 101 that changes is calculated, ultimately forming the relationship between the speed of the drive gear shaft 3 and the area of ​​the sector plate body 101 that changes. Externally, based on the transmission ratio and actual conditions, a corresponding speed is applied to the drive gear shaft 3. The drive gear shaft 3 drives the internal meshing gear 402 of the central transmission body 4 to rotate. Since the central transmission body 4 is a single unit, the internal meshing gear 402 transmits torque to the disk 401. The three sector plate sliders 1 that cooperate with the disk 401 move relative to each other, that is, the slider 102 drives the sector plate body 101 to move towards the center. The area of ​​the floating ring formed by the three sector plate sliders 1 will decrease, thereby realizing the adjustment of the closing force, and thus achieving the characteristics of easy opening and controllability. The invention uses pure mechanical transmission internally, which is stable and reliable, and can be used in petroleum, chemical, aerospace and other fields.

[0037] The present invention will be further described below with reference to Examples 1 to 4.

[0038] Example 1

[0039] An adjustable back pressure area and controllable opening floating ring for non-contact mechanical seals includes a sector-shaped plate slider 1, a rear cover 2, a drive gear shaft 3, and a central transmission body 4.

[0040] The sector plate slider 1 includes a sector plate body 101 and a slider 102 disposed inside the sector plate body 101, and the bottom surface of the slider 102 is toothed.

[0041] The rear cover 2 is a circular cover with a circumferential wall 201 at the edge and a through hole 202 at the center. A circular hole 203 is opened on the inner surface of the rear cover 2. The circular hole 203 is not a through hole and is close to the through hole 202. A first O-ring 5 is provided at the top of the circumferential wall 201.

[0042] The central transmission body 4 includes a disk 401 and an internal meshing gear 402. The disk 401 has a hole 403 in the center and a plane thread 404 around the hole 403 on the top surface of the disk 401. The hole 403 is connected to the top edge of the cylindrical wall 405. The internal meshing gear 402 is fixed to the bottom edge of the cylindrical wall 405. The inner diameter of the internal meshing gear 402 is larger than the diameter of the through hole 202.

[0043] There are three sector-shaped sliders 1, distributed along the circumference, and the sector-shaped plate bodies 101 are all at 120°. The bottom surface of the sector-shaped plate body 101 is in close contact with the top surface of the disk 401, and the teeth on the bottom surface of the slider 102 slide in contact with the planar thread 404 on the top surface of the disk 401. A second O-ring 6 is provided around the planar thread 404, and the second O-ring 6 is in close contact with the bottom surface of the sector-shaped plate body 101. The rear cover 2 covers the bottom surface of the central transmission body 4, and the top of the circumferential wall 201 contacts the edge of the disk 401. The first O-ring 5 is located between the two, and the circular hole 203 is exposed from the inside of the internal meshing gear 402. The cylindrical key at the end of the drive gear shaft 3 is embedded in the circular hole 203, and the gear of the drive gear shaft 3 meshes with the internal meshing gear 402.

[0044] Example 2

[0045] Except that the fan-shaped plate body 101 and the slider 102 are integrally formed, the rest is the same as in Example 1.

[0046] Example 3

[0047] Except for the rear cover 2 being connected to the central transmission body 4 via an inlay structure, the rest is the same as in embodiment 2.

[0048] Example 4

[0049] As attached Figure 9 As shown, in a non-contact mechanical seal, the floating ring 7 of the present invention from Example 1 is installed at the lower part of the spring seat 15. The shaft of the drive gear shaft 3 passes through the bushing II 18, and the lower part of the spring seat 15 is connected to the atmosphere. The working process of the floating ring 7 of the present invention in a non-contact mechanical seal is as follows: high-pressure gas enters from the inlet 9, and the shaft 14 drives the rotating ring 11 to rotate through the pin 13. Usually, a series of special grooves are machined on the surface of the rotating ring 11. As it rotates, the gas is pumped inward to the root of the groove. The grooveless area outside the root is the sealing dam, which resists the gas flow and increases the gas film pressure. The pressure generated between the mating surfaces causes the surface of the floating ring 7 of the present invention to separate from the rotating ring 11, maintaining a very small gap, so that the gas film is in a steady state. This ensures that the dry gas seal is in the optimal state, which is the purpose of the present invention—the opening force and the closing force are equal. The closing force is composed of the internal and external medium pressures and the action of the auxiliary sealing element and the spring 16 on the floating ring 7 of the present invention, i.e., the static contact pressure. The force exerted on the sealing end face is calculated using the following formula:

[0050] Closing force ;

[0051] In the formula, The inner diameter of the sealing ring; The outer diameter of the sealing ring;

[0052] When in the open state, if the opening force and closing force are not equal, a speed can be applied to the drive gear shaft 3 to adjust the floating ring 7 at its maximum area according to the aforementioned transmission ratio. This allows for adjustment of the closing force, ensuring that the opening and closing forces are equal, thus bringing the air film into a steady state and achieving better sealing performance.

Claims

1. A floating ring with adjustable back pressure area and controllable opening for non-contact mechanical seals, comprising a sector-shaped plate slider (1), a rear cover (2), a drive gear shaft (3), and a central transmission body (4), characterized in that: The sector plate slider (1) includes a sector plate body (101) and a slider (102) disposed inside the sector plate body (101), the bottom surface of the slider (102) being toothed; The rear cover (2) is a circular cover with a circumferential wall surface (201) at the edge and a through hole (202) in the center. A circular hole (203) is opened on the inner surface of the rear cover (2). The circular hole (203) is not a through hole and is close to the through hole (202). A first O-ring (5) is provided on the top of the circumferential wall surface (201). The central transmission body (4) includes a disc (401) and an internal meshing gear (402). The disc (401) has a hole (403) in the center. A plane thread (404) is provided around the hole (403) on the top surface of the disc (401). The hole (403) is connected to the top edge of the cylindrical wall (405). The internal meshing gear (402) is fixed to the bottom edge of the cylindrical wall (405). The inner diameter of the internal meshing gear (402) is larger than the diameter of the through hole (202). There are three sector-shaped sliders (1), distributed along the circumference, and the sector-shaped plate bodies (101) are all 120°. The bottom surface of the sector-shaped plate body (101) is close to the top surface of the disk (401), and the teeth on the bottom surface of the slider (102) slide with the planar thread (404) on the top surface of the disk (401). A second O-ring (6) is provided around the planar thread (404), and the second O-ring (6) is close to the bottom surface of the sector-shaped plate body (101). The rear cover (2) covers the bottom surface of the central transmission body (4), and the top of the circumferential wall (201) contacts the edge of the disk (401). The first O-ring (5) is located between the two, and the round hole (203) is exposed from the inside of the internal meshing gear (402). The cylindrical key at the end of the drive gear shaft (3) is embedded in the round hole (203), and the gear of the drive gear shaft (3) meshes with the internal meshing gear (402).

2. The adjustable back pressure area and controllable opening floating ring for non-contact mechanical seals according to claim 1, characterized in that... The fan-shaped plate body (101) and the slider (102) are integrally formed.

3. The adjustable back pressure area and controllable opening floating ring for non-contact mechanical seals according to claim 1, characterized in that... The rear cover (2) is connected to the central transmission body (4) through an inlay structure.

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