Anti-deflection double-floating dry operation seal with self-cooling function

Abstract

The anti-deflection double-floating dry operation seal comprises a shaft sleeve, a movable ring and a static ring, the movable ring is arranged on the outer side of the shaft sleeve, and the movable ring and the shaft sleeve are in transmission through a shifting fork; the static ring is arranged in a cavity of the static ring seat; a first elastic piece is arranged on one side, deviating from the static ring, of the movable ring, so that the movable ring axially floats relative to the shaft sleeve; at least one second elastic piece is arranged in a cavity of the static ring seat and connected with a first push ring, and the first push ring is tightly attached to the side, away from the movable ring, of the static ring through a fourth O-shaped ring, so that the first push ring and the fourth O-shaped ring float along with the static ring all the time. The side, away from the movable ring, of the static ring is subjected to static elastic force applied by the second elastic piece and first medium pressure. The side, away from the static ring, of the movable ring is subjected to dynamic elastic force applied by the first elastic piece and second medium pressure. In the process that the dynamic ring and the static ring are converted into the balance state from the non-balance state, the end faces of the dynamic ring and the static ring can make contact all the time and keep attached, and bidirectional floating is achieved in the axial direction.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of dry running seal, in particular to a self-cooled anti-yaw double-floating dry running seal. BACKGROUND

[0002] Dry running seal is a common type of seal, which has the advantages of simple structure and no need for auxiliary system. As shown in Figure 20 , the dynamic ring and the static ring are in contact operation, wherein the dynamic ring has a spring at the back, which can float up and down with the shaft; the static ring is pressed by the pressing plate 36 and fixed on the connecting disc.

[0003] The existing dry running seal has two shortcomings: First, it can only be applied to low-speed equipment: since the seal end face is in contact operation, and the seal has no cooling and lubrication measures, only the good self-lubricating property and high thermal conductivity coefficient of the seal ring material are relied on to improve the service life of the seal. However, when the seal speed is too high, the seal end face will be severely worn due to the accumulation of too much heat, and the wear debris will further exacerbate the wear of the seal end face. Table 1 shows the relationship between the linear velocity and the wear amount of a certain parameter of a conventional dry running seal tested in a factory.

[0004] Table 1: Relationship between linear velocity and wear amount of conventional dry running seal

[0005] As can be seen from Table 1, the wear amount of the conventional dry running seal increases exponentially with the increase of the linear velocity, so the conventional dry running seal can only be applied to low-speed equipment such as reaction kettles, mixers, etc. It is rarely seen that dry running seals are applied to higher-speed equipment such as pumps, centrifuges, high-speed mixers, etc.

[0006] Second, the seal has poor anti-yaw capability. As shown in Figure 20 , the static ring 13, the pressing plate 36 and the tool connecting disc 26 are connected as a whole through screws, wherein the pressing plate 36 completely presses the static ring 13, and the static ring 13 cannot move relative to the tool connecting disc 26. The tool connecting disc 26 is assembled with the equipment cavity through connecting screws 37, as shown in Figure 21As shown, the main shaft 300 is vertically arranged, and the main shaft center line 301 is also vertically arranged. The sealing moving ring and other parts are fixed on the main shaft 300 by a set screw. Under the action of the dynamic elastic force and the second medium pressure, the main shaft / moving ring center line 303 is theoretically the same as the main shaft center line 301. When the device cavity is not perpendicular to the main shaft 300, assuming that the included angle between the device cavity center line and the main shaft center line 301 is 1°, since the tool connecting disc 26 is directly fixed on the cavity and the static ring 13 is integrated with the tool connecting disc 26 through the screw connection, correspondingly, the included angle between the cavity / static ring center line 302 and the main shaft center line 301 is also 1°. This results in the existence of the included angle between the static ring end face and the moving ring end face, as shown in Figure 22 As shown, the moving ring end face and the static ring are not uniformly contacted on the entire surface, and the fit is uneven, so that the seal is easy to be eccentrically worn, which affects the service life of the seal. At present, the low-speed equipment applied by the dry running seal generally has poor precision, which has an adverse effect on the long-period use of the dry running seal.

[0007] CN105889515A discloses a contact type dry running seal, which comprises a sealing structure arranged between a flange plate, an end cover and a shell, a shaft sleeve arranged on a rotating shaft, a static ring seat fixedly installed on the shell, a spring seat fixedly sleeved on the shaft sleeve, and a sealing pair and an elastic assembly symmetrically arranged on both sides of the spring seat. The sealing pair comprises a moving ring and a static ring matched by a sealing end face. The moving ring is sleeved on the spring seat. The elastic assembly acts on the moving ring end face to make the sealing end faces of the moving ring and the static ring closely fit. The static rings on both sides are fixedly installed on the static ring seat and the flange plate, respectively. A bearing is arranged between the static ring seat and the shaft sleeve. This technical solution does not introduce a driving cooling or lubricating structure, and does not mention the optimization of the thermal stability or self-lubricating performance of the sealing material under high-speed friction. Therefore, although this structure can improve the service life of the seal to a certain extent, it still essentially relies on the self-lubricating property and thermal conductivity of the material to maintain operation, and does not fundamentally solve the problem of heat accumulation and wear aggravation at high speed.

[0008] Therefore, the present application proposes a high-speed dry running seal that can adapt to the environment with poor equipment precision, so that it can be used in a low-speed stirred tank with poor precision for a long period of time without auxiliary gas source and sealing liquid, or used in a device with a relatively high rotating speed (≤4000 rpm) for a long period of time. SUMMARY

[0009] The existing dry running seal has two significant technical limitations. First, its application scope is limited to low-speed operating environments. This type of seal structure adopts an end face contact design, lacks active cooling and lubrication systems, and relies solely on the self-lubricating properties and thermal conductivity of the sealing material to maintain operational stability. When the device speed exceeds a critical value, the heat generated at the friction interface accelerates material loss, and the accumulation of wear particles on the contact surface forms a vicious cycle, leading to rapid degradation of seal performance. Experimental data show that when the linear speed increases from 0.5 m / s to 8 m / s, the wear increases exponentially, from 2.3 um to 863.5 um. This performance degradation characteristic determines that this technology is mainly applicable to reaction kettles, mixers, and other operating scenarios with a rotational speed below 8 m / s, making it difficult to meet the sealing needs of high-speed rotating machinery such as pumps and centrifuges.

[0010] Secondly, the existing dry running seal has obvious deficiencies in adapting to installation errors of the device. Its fixed structure adopts a rigid connection method, and the static ring assembly is fixed by a pressure plate and a tool connecting disc to form a fixed unit, which is rigidly connected with the device cavity. When there is a small inclination deviation (such as 1°) between the main shaft and the cavity, this error will be directly transmitted to the seal end face, causing the contact surface of the dynamic ring and the static ring to form an inclination with the same angle. This non-uniform contact state can cause local stress concentration, resulting in uneven wear of the end face and thus shortening the service life of the seal assembly. It is worth noting that the low-speed devices where this technology is mainly applied generally have low manufacturing precision. The combination of this structural defect and operating conditions further exacerbates the instability of seal performance.

[0011] In view of the deficiencies of the prior art, the present application provides an anti-deflection double-floating dry running seal with self-cooling, which comprises a shaft sleeve, a dynamic ring and a static ring. The dynamic ring is arranged outside the shaft sleeve and is connected between the shaft sleeve and the dynamic ring through a yoke. The static ring is arranged in the cavity of a static ring seat. A first elastic member is arranged on the side of the dynamic ring away from the static ring, so that the dynamic ring floats axially relative to the shaft sleeve. At least one second elastic member is arranged in the cavity of the static ring seat, and the second elastic member is connected with a first push ring. The first push ring is tightly attached to the side of the static ring away from the dynamic ring through a fourth O-ring, so that the first push ring and the fourth O-ring always float with the static ring. The side of the static ring away from the dynamic ring is subjected to a static elastic force exerted by the second elastic member and a first medium pressure. The side of the dynamic ring away from the static ring is subjected to a dynamic elastic force exerted by the first elastic member and a second medium pressure. Under the axial dynamic action of the static elastic force, the first medium pressure, the dynamic elastic force and the second medium pressure, the sealing end faces of the dynamic ring and the static ring can always contact and adhere during the transition from the unbalanced state to the balanced state of the dynamic ring and the static ring, and realize bidirectional floating in the axial direction.

[0012] The dynamic ring and the static ring of the application are subjected to the combined action of dynamic spring force, static spring force, and the pressure of the first and second media on both sides. When the seal is in operation, these axial forces facilitate the transition of the dynamic ring and the static ring from a non-equilibrium state to an equilibrium state in dynamic changes, ensuring that the sealing end faces of the two are always in contact and remain in close contact, while achieving bidirectional axial floating. This design significantly improves the adaptability of the sealing surface to axial displacement and pressure fluctuations. In particular, during the start-up and shutdown stages or under sudden pressure changes, the stability of the end face adhesion force can still be maintained, avoiding the risk of leakage caused by instantaneous separation, thereby alleviating the problem of end face separation caused by rigid fixation in traditional structures, and partially solving the defect that low-speed seals cannot cope with fluctuations in working conditions.

[0013] According to a preferred embodiment, the static ring is concentric with the step in the cavity of the static ring seat; there is a first gap and a second gap between the static ring and the static ring seat, so that when the static ring floats axially along the rotation axis, the static ring seat does not directly contact the static ring and does not interfere with the floating of the static ring.

[0014] The design of the first gap and the second gap allows the static ring to float axially without directly contacting the static ring seat, avoiding structural interference and ensuring the reliability of the free floating of the static ring. This technical effect effectively reduces the additional constraint stress caused by assembly errors or thermal deformation, enhances the fault tolerance of the sealing assembly to small deformations, and thus reduces the load effect caused by installation deviation transmitted to the sealing end face, improving the stability and life of the sealing operation.

[0015] According to a preferred embodiment, the dynamic ring is concentric with the shaft sleeve; there is a third gap between the dynamic ring and the shaft sleeve, so that when the dynamic ring floats axially, the dynamic ring does not directly contact the shaft sleeve and does not interfere with the floating of the dynamic ring.

[0016] The third gap allows the dynamic ring to float axially without physical obstruction from the shaft sleeve structure, achieving interference-free floating. This design not only ensures the flexibility of the axial movement of the dynamic ring, but also reduces the additional resistance and local wear caused by the friction of the mating surfaces, improving the sensitivity of the dynamic ring to pressure changes and helping to maintain the consistency of the end face adhesion, especially under conditions of vibration or axial movement, still maintaining good sealing performance.

[0017] According to a preferred embodiment, a plurality of one-way microgrooves are provided on the dynamic ring end face of the dynamic ring cooperating with the static ring, the small diameter of the one-way microgrooves is smaller than the inner diameter of the static ring end face, to ensure that the gas inside the dynamic ring can enter the one-way microgrooves; the outer diameter of the one-way microgrooves is smaller than the outer diameter of the static ring end face, to ensure that the gas inside the dynamic ring cannot directly enter the outside of the dynamic ring through the one-way microgrooves.

[0018] The structure forms a fluid dynamic pressure effect when the end face of the rotating ring rotates, generates a directional gas film support force, partially offsets the contact pressure of the end face of the rotating ring, and reduces the actual contact stress and friction power consumption. The technical effect helps to reduce the direct contact area between the end face of the rotating ring and the end face of the static ring, suppresses the temperature rise and wear in the dry friction state, and significantly delays material loss during high-speed operation, thereby alleviating the problem of rapid wear after speed improvement of traditional dry-running seals.

[0019] According to a preferred embodiment, a plurality of bidirectional microgrooves are arranged on the end face of the rotating ring matched with the static ring. The outer diameter of the bidirectional microgrooves is smaller than the outer diameter of the end face of the static ring, and the inner diameter of the bidirectional microgrooves is smaller than the inner diameter of the end face of the static ring, so as to ensure that the gas on the inner side of the rotating ring cannot directly enter the outer side of the rotating ring through the bidirectional microgrooves.

[0020] The bidirectional microgrooves can form symmetrical fluid dynamic pressure support between the end faces of the rotating ring, enhance the gas film stiffness and stability, and further optimize the lubrication state between the end face of the rotating ring and the end face of the static ring. Compared with unidirectional grooves, bidirectional microgrooves are more suitable for bidirectional rotation or frequent start-stop working conditions, improve the adaptability of the seal under complex motion conditions, help to maintain low friction and low wear operation of the end face, and prolong the service life.

[0021] According to a preferred embodiment, a plurality of spiral grooves are uniformly arranged on the outer side of the shaft sleeve. When the shaft sleeve rotates with the rotating shaft (21), the spiral grooves drive the gas in the spiral grooves to flow along the grooves, and the high-temperature gas on the rotating ring side is transported to the atmosphere side through the spiral grooves, forming a slight negative pressure on the rotating ring side, and the normal-temperature gas on the atmosphere side flows to the rotating ring side through the gap between the static ring seat and the shaft sleeve, thereby forming a circulation; the high-temperature gas on the rotating ring side is continuously transported to the atmosphere side, and the normal-temperature gas on the atmosphere side is supplemented to the rotating ring side and exchanges heat with the rotating ring and the static ring, thereby taking away the heat generated by the wear of the rotating ring and the static ring. By arranging the structure in this way, a self-induced air cooling mechanism is formed, which can continuously take away the heat of the sealing end face without an external cooling source, and effectively controls the temperature of the friction interface.

[0022] According to a preferred embodiment, a plurality of shaft sleeve bidirectional grooves are arranged on the outer side of the shaft sleeve. When the shaft sleeve rotates with the rotating shaft, the shaft sleeve bidirectional grooves drive the gas in the shaft sleeve bidirectional grooves to rotate together, accelerate the flow of the gas on the rotating ring side and the atmosphere side, and make the heat exchange of the high-temperature gas on the rotating ring side and the normal-temperature gas on the atmosphere side more sufficient, so as to take away the heat generated by the wear of the end faces of the rotating ring and the static ring. The structure strengthens the heat exchange process in the sealing cavity, makes the mixing of the high-temperature gas and the external cold gas more sufficient, and improves the overall heat dissipation capacity. Combined with the air induction effect of the spiral grooves, the shaft sleeve bidirectional grooves further improve the stability and response speed of the cooling system, and can effectively prevent the sealing failure caused by local overheating, especially under high-speed or continuous operation conditions.

[0023] According to one preferred embodiment, the drive ring is connected with the shaft sleeve and fixed on the rotating shaft so as to rotate with the rotating shaft; the drive ring is provided with a plurality of arc-shaped grooves on the side facing the drive sealing side of the seal; the arc-shaped grooves extend outward from the inner diameter position of the drive ring in the radial direction of the rotating shaft, and the cross-sectional area of the arc-shaped grooves in the circumferential direction gradually increases with the outward extension; the inner hole position of the drive ring is provided with a straight groove which penetrates the inner hole of the drive ring and communicates with the arc-shaped grooves; when the drive ring rotates with the rotating shaft, the arc-shaped grooves compress the normal temperature gas in the atmospheric environment on the outside of the drive ring and transport the normal temperature gas to the inner diameter position of the drive ring; part of the normal temperature gas flows to the atmospheric environment on the side away from the seal of the drive ring through the straight groove; the other part of the normal temperature gas flows to the sealing side of the movable ring and the static ring and forms linkage with the spiral groove on the outside of the shaft sleeve, thereby taking away the high temperature gas at the sealing end surface position, so that the high temperature gas flows to the atmospheric environment through the straight groove. The active air induction mechanism formed in this way significantly enhances the flow and pressure of the cooling gas flow, improves the heat exchange efficiency, and can still maintain effective cooling of the sealing end surface under high sealing specific pressure or high temperature environment conditions, thereby further expanding the application range of the seal.

[0024] According to one preferred embodiment, the shaft sleeve is provided with a shaft sleeve step for limiting the displacement of the movable ring to the atmospheric side, and the movable ring seat is arranged on the side of the movable ring facing the medium, and the displacement of the movable ring seat to the medium side is limited by the first collar; a cylindrical pin is arranged on the outside of the shaft sleeve, one end of the cylindrical pin is fixed on the shaft sleeve, and the other end of the cylindrical pin extends into the pin groove of the movable ring, so that the movable ring can rotate with the shaft sleeve.

[0025] The multiple limiting and transmission structures formed in this way ensure that the movable ring maintains axial freedom and circumferential synchronism during floating, avoid transmission failure or jamming caused by floating, and improve the reliability and safety of the seal operation.

[0026] According to one preferred embodiment, an O-ring is arranged in the groove at the outer diameter of the static ring made of hard material, so that the first medium pressure only acts on the side of the static ring facing the medium; the movable ring made of soft material is arranged in the movable ring seat, the movable ring seat is fixed on the outside of the shaft sleeve through a set screw, and the second push ring and the fifth O-ring are arranged between the movable ring and the movable ring seat. The material and structure matching design of the present application takes into account the wear resistance and compliance, the hard static ring provides a stable sealing surface, and the soft movable ring has better floating response capability and anti-deflection adaptability, and the two cooperate to maintain the relative parallel contact of the end surfaces when there is a small shaft deflection angle (such as 1°), reduce local stress concentration, improve wear distribution uniformity, thereby effectively alleviating the early failure problem caused by installation errors. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 is the cross-sectional view of the first anti-deflection double-floating dry-running seal with self-cooling provided by the present application; Figure 2 This is a schematic diagram of the floating sealing stationary ring provided by the present invention; Figure 3 This is a schematic diagram of the floating sealing ring provided by the present invention; Figure 4 This is a schematic diagram of the axial force on the sealing dynamic and static rings provided by the present invention; Figure 5 This is a schematic diagram of the normal clearance between the stationary ring and the stationary ring seat provided by the present invention; Figure 6 This is a schematic diagram of the stationary ring seat deflection provided by the present invention; Figure 7 This is a schematic diagram of the normal clearance between the rotating ring and the bushing provided by the present invention; Figure 8 This is a schematic diagram of the bushing misalignment provided by the present invention; Figure 9 This is a schematic diagram of the unidirectional microgroove on the end face of the moving ring provided by the present invention; Figure 10 This is a schematic diagram of the bidirectional microgroove on the end face of the moving ring provided by the present invention; Figure 11 This is a schematic diagram of the spiral groove on the bushing provided by the present invention; Figure 12 This is a schematic diagram of the bidirectional groove on the bushing provided by the present invention; Figure 13 This is a planar schematic diagram of the arc-shaped groove of the drive ring provided by the present invention; Figure 14 This is a three-dimensional schematic diagram of the arc-shaped groove of the drive ring provided by the present invention; Figure 15 This is a schematic diagram of the bidirectional groove of the drive ring provided by the present invention; Figure 16 This is a schematic diagram of gas flow at the sealing position provided by the present invention; Figure 17 This is a cross-sectional view of the second type of self-cooling anti-sway double floating dry-running seal provided by the present invention; Figure 18 This is a cross-sectional view of the third type of self-cooling anti-sway double floating dry operation seal provided by the present invention. Figure 19 This is a schematic diagram of the experimental fixture provided by the present invention; Figure 20 This is a cross-sectional view of the existing dry-run seal provided by the present invention; Figure 21 This is a schematic diagram of the angle between the center line of the cavity / stationary ring and the center line of the main shaft in the existing dry-running seal provided by the present invention; Figure 22 This is a schematic diagram of uneven contact between the end faces of the rotating ring and the stationary ring in a conventional dry-running seal provided by the present invention.

[0028] List of reference signs 1: bushing; 2: set screw; 3: cylindrical pin; 4: cylindrical head screw; 5: static ring seat; 6: first O-ring; 7: dynamic ring; 8: second O-ring; 9: check ring; 10: first elastic member; 11: third O-ring; 12: first clamping ring; 13: static ring; 14: second clamping ring; 15: fourth O-ring; 16: first push ring; 17: second elastic member; 18: driving ring; 19: axis center line; 20: equipment cavity; 21: rotating shaft; 22: dynamic ring seat; 23: transmission pin; 24: bushing step; 25: test bench support; 26: tool connecting disc; 27: tool sealing cavity; 28: GBI interface; 29: pressure reducing valve; 30: compressed gas; 31: experimental shaft; 32: connecting port; 33: wire; 34: spring; 35: screw; 36: pressing plate; 37: connecting screw; 38: second push ring; 39: fifth O-ring; 40: third elastic member; 41: micro groove; 71: first gap; 72: second gap; 73: third gap; 74: dynamic ring end face; 75: one-way micro groove; 76: dynamic ring inner side; 77: dynamic ring outer side; 78: two-way micro groove; 101: helical groove; 102: bushing two-way groove; 131: fourth gap; 132: fifth gap; 133: sixth gap; 134: seventh gap; 180: driving sealing side; 181: arc groove; 182: straight groove; 183: driving ring two-way groove; 191: first auxiliary line; 192: second auxiliary line; 200: atmospheric side; 201: medium side; 202: static ring movable direction; 203: dynamic ring movable direction; 204: end face groove dynamic pressure; 205: normal temperature gas flow direction; 206: high temperature gas flow direction; 207: dynamic ring side; 208: bushing rotation direction; 209: atmospheric environment; 210: sealing side of dynamic ring and static ring; 211: side of driving ring away from sealing; 212: test bench motor side; 300: main shaft; 301: main shaft center line; 302: cavity / static ring center line; 303: main shaft / dynamic ring center line. DETAILED DESCRIPTION

[0029] The following will be described in detail with reference to the drawings.

[0030] The main terms of the present application are explained.

[0031] Atmospheric environment 209 refers to the external environment in which the seal works. If the seal is installed outdoors, the atmospheric environment 209 is outdoor gas; if the seal is installed indoors, the atmospheric environment 209 refers to indoor gas.

[0032] Medium side 201, also known as medium end, refers to the side closer to the medium. For example, part A is closer to the medium relative to part B, then part B is called the medium side 201 of part A.

[0033] Medium-facing side or atmosphere-facing side: refers to the side of the part that is closer to the medium or the side that is closer to the atmosphere. For example, if the left side of part C is closer to the medium than the right side, then the left side of part C is called the medium-facing side and the right side is called the atmosphere-facing side.

[0034] Atmosphere side 200: also known as the atmosphere end, refers to the side that is relatively closer to the atmosphere 209. For example, if part D is closer to the atmosphere 209 than part E, then the atmosphere side 200 of part E has part D.

[0035] Soft material: refers to a material with relatively low hardness in a sealing dynamic and static ring. The dry running sealing end face is subject to wear and tear, and the sealing end face is usually not made of the same material. When different materials are used as the sealing end face, the softer and more easily worn material can be called a soft material. For example, in a conventional sealing pair, graphite against silicon carbide, graphite is a soft material and silicon carbide is a hard material. The sealing end face refers to the direct contact surface between the dynamic ring end face and the static ring end face.

[0036] Microscopic groove 41: refers to a groove with a depth of microns, such as a dry gas seal dynamic pressure groove with a depth of 5-10 um.

[0037] Load coefficient K: a general parameter for mechanical seals, refers to the ratio of the effective area Ae of the medium pressure on the compensation ring to the end face area A, i.e. K=Ae / A.

[0038] The existing dry running seal has two shortcomings: First, the application range is limited to low-speed operation: in this sealing structure, the sealing end face is a contact type running, and the sealing end face itself lacks external cooling and lubrication design, its running stability mainly depends on the excellent self-lubricating performance and high thermal conductivity of the sealing ring material, to delay the temperature rise of the end face and prolong the service life. However, when the speed of the main shaft 300 increases, the heat generated by the friction of the sealing end face is difficult to dissipate in time, resulting in a sharp rise in temperature, causing serious wear and tear. If the particles generated by wear and tear are retained in the end face area, they will also form a grinding effect, further accelerating the damage to the sealing end face.

[0039] Table 1: Relationship between linear velocity and wear of conventional dry running seal

[0040] As can be seen from Table 1, as the linear velocity increases, the wear of the conventional dry running seal increases exponentially, so the conventional dry running seal can only be applied to low-speed equipment such as reaction kettles, mixers, etc. It is rare to see dry running seals applied to higher speed equipment such as pumps, centrifuges, high-speed mixers, etc.

[0041] Second, the sealing structure has weak anti-deflection ability. For example,Figure 20 As shown, the stationary ring 13, pressure plate 36, and tooling connecting plate 26 are connected as a single unit by screws. The pressure plate 36 completely presses the stationary ring 13, preventing relative movement between it and the tooling connecting plate 26. The tooling connecting plate 26 is fixed to the equipment cavity by connecting screws 37. Figure 21 As shown, in the structure where the spindle 300 is vertically mounted, the spindle centerline 301 is vertical. Components such as the sealing ring 7 are mounted on the spindle 300 using set screws. Theoretically, under the action of the spring force and the pressure of the second medium, the spindle / ring centerline 303 should be aligned with the spindle centerline 301. However, when the equipment cavity is not perpendicular to the spindle 300, if there is a 1° angle between the cavity centerline and the spindle centerline 301, the cavity / ring centerline 302 will also tilt by 1° because the tooling connection plate 26 is directly fixed to the cavity, and the stationary ring 13 is rigidly connected to the tooling connection plate 26 with screws. Figure 22 As shown, this will result in an angle between the stationary ring end face and the rotating ring end face 74, preventing them from achieving uniform contact around the entire circumference and resulting in only localized contact. This easily leads to uneven wear and significantly reduces the seal life. Furthermore, low-speed equipment currently using dry-running seals generally has low machining and assembly precision and poor shaft alignment, further limiting the long-term stable operation capability of this type of seal.

[0042] To address the shortcomings of existing technologies, this invention provides a self-cooling, anti-sway, double-floating dry-running seal.

[0043] Example 1 The self-cooling, anti-yaw, double-floating dry-run seal of the present invention is as follows: Figure 1 As shown, the set screw 2 connects the drive ring 18 to the bushing 1 and fixes it to the rotating shaft 21, allowing it to rotate together with the rotating shaft 21. The third O-ring 11 can prevent the medium from leaking from the gap between the bushing 1 and the rotating shaft 21.

[0044] like Figure 1As shown, the moving ring 7 is located on the outside of the bushing 1, near the stationary ring 13 and defined by a first retaining ring 12 on the bushing 1. The moving ring 7 and the bushing 1 are connected by a fork: symmetrically distributed transmission grooves are provided on the outside of the moving ring 7, corresponding one-to-one with the forks on the outside of the bushing 1. The protruding forks on the bushing 1 insert into the transmission grooves on the moving ring 7. When the bushing 1 rotates with the rotating shaft 21, the forks will drive the moving ring 7 to rotate together. A first elastic element 10 is provided on the side of the moving ring 7 facing away from the stationary ring 13. The first elastic element 10 is, for example, a wave spring. The position of the first elastic element 10 facing away from the moving ring 7 is defined by the bushing step 24 on the outside of the bushing 1. Because the first elastic element 10 is elastic, by reasonably designing the gap between the moving ring 7 and the bushing 1, the moving ring 7 can float axially relative to the bushing 1. Under the action of the dynamic elastic force of the first elastic element 10 and the pressure of the second medium, the retaining ring 9 tightly presses the second O-ring 8, making the second O-ring 8, the retaining ring 9 and the rotating ring 7 into a whole, floating together along the axial direction and rotating together with the rotating shaft 21. The second O-ring 8 can prevent the medium from leaking from the gap between the bushing 1 and the rotating ring 7.

[0045] like Figure 1 As shown, the cylindrical head screw 4 secures the stationary ring seat 5 to the equipment cavity. A first O-ring 6 prevents media leakage from the gap between the stationary ring seat 5 and the equipment cavity. The stationary ring 13 is disposed within the stationary ring seat 5. A second retaining ring 14 limits the displacement range of the stationary ring 13 within the stationary ring seat 5. Multiple evenly distributed second elastic elements 17 are disposed within the stationary ring seat 5. The second elastic elements 17 are preferably cylindrical springs. The second elastic elements 17 push the first push ring 16, which in turn pushes the fourth O-ring 15 to press tightly against the stationary ring 13, causing the first push ring 16 and the fourth O-ring 15 to always float with the stationary ring 13. In other words, the fourth O-ring 15 is positioned between the first push ring 16 and the side of the stationary ring 13 facing away from the moving ring 7. The second elastic elements 17 push the first push ring 16, causing the stationary ring 13 to float axially on the fourth O-ring 15 and achieve a seal.

[0046] The fourth O-ring 15 is used to prevent media leakage from the gap between the stationary ring seat 5 and the stationary ring 13. The cylindrical pin 3 is hammered into the stationary ring seat 5 through an interference fit. Several arc-shaped notches are machined on the outer circumference of the stationary ring 13 and the first push ring 16. These arc-shaped notches pass through the cylindrical pin 3, preventing relative rotation between the stationary ring 13, the first push ring 16 and the stationary ring seat 5, thus preventing rotation of the stationary ring 13 and the first push ring 16.

[0047] like Figure 2 The stationary ring 13 is located in the cavity of the stationary ring seat 5, and its movable direction is 202. The second retaining ring 14 restricts the range of movement of the stationary ring 13, allowing the stationary ring 13 to float axially within the range of the fourth gap 131 and the fifth gap 132.

[0048] like Figure 3The movable ring 7 is shown to move in the direction 203, and the first retaining ring 12 restricts the range of movement of the movable ring 7. The movable ring 7 can float axially within the range of the first gap 71 and the second gap 72.

[0049] like Figure 4 As shown, the double arrows indicate the dynamic pressure 204 of the end face groove. The end face of the moving ring 7 facing the stationary ring 13 has a micro-groove 41. The micro-groove 41 is a dynamic pressure groove (end face groove). The side of the stationary ring 13 with the second elastic element 17 is subjected to the static elastic force (F) of the second elastic element 17. 静弹 ) and the first medium pressure (F 介质1 The side of the moving ring 7 with the first elastic element 10 is subjected to the dynamic force (F) of the wave spring. 动弹 ) and second medium pressure (F 介质2 ).

[0050] Under the axial dynamic action of static elastic force, first medium pressure, dynamic elastic force and second medium pressure, during the process of the moving ring 7 and the stationary ring 13 changing from an unbalanced state to a balanced state, the sealing end faces of the moving ring 7 and the stationary ring 13 can always contact and remain in contact, and achieve bidirectional floating in the axial direction.

[0051] Specifically, under the influence of static elastic force, first medium pressure, dynamic elastic force, and second medium pressure on both sides, the rotating ring end face 74 of the rotating ring 7 and the stationary ring end face of the stationary ring 13 can always be in contact. Due to the sealing and isolation function of the fourth O-ring 15 and the special structural design, the axial thrust from the medium on the rotating ring end face 74 of the rotating ring 7 and the stationary ring end face of the stationary ring 13 is not the same, i.e., F 介质1 <F 介质2 The present invention can balance the total force on the moving ring 7 and the stationary ring 13 by adjusting the magnitude of the elastic force. Specifically, by adjusting the first stiffness and number of the second elastic element 17 and the second stiffness of the first elastic element 10, the moving ring 7 and the stationary ring 13 can achieve force balance even when they are in different positions and the elastic force they receive is different.

[0052] like Figure 1 As shown, at this time, the moving ring 7 and the stationary ring 13 are in theoretical equilibrium. When the entire structure composed of the moving ring 7 and the stationary ring 13 moves towards... Figure 1 When the axis moves to the left as shown, the compression amplitude of the second elastic element 17 on the back of the stationary ring 13 increases, and the elastic force increases, while the compression amplitude of the first elastic element 10 on the back of the moving ring 7 decreases, and the elastic force decreases, until equilibrium is reached. When the entire assembly of the moving ring 7 and the stationary ring 13 moves to the left... Figure 1When the shaft moves to the right, the compression of the second elastic member 17 at the back of the static ring 13 decreases, the elastic force decreases, and the compression of the first elastic member 10 at the back of the dynamic ring 7 increases, the elastic force increases, until the balance is reached. The whole of the dynamic ring 7 and the static ring 13 from the unbalanced state to the balanced state, that is, the bidirectional floating ability of the seal, enables the dynamic ring end face 74 of the dynamic ring 7 and the static ring end face of the static ring 13 to always be in close contact.

[0053] Preferably, because Figure 4 The F 静弹 , F 介质1 , F 动弹 , F 介质2 The combined action of the four forces, the dynamic ring 7 and the static ring 13 tend to close. When the sealing dynamic ring 7 rotates with the rotating shaft 21, wear occurs between the dynamic ring 7 and the static ring 13, at which time the gas inside the sealing ring is sucked into the dynamic ring 7 and the static ring 13 under the action of the micro groove 41 of the dynamic ring end face 74, a certain dynamic pressure is generated between the dynamic ring 7 and the static ring 13, which makes the dynamic ring end face 74 and the static ring end face tend to open, reducing the sealing wear. According to the narrow groove theory, the general spiral groove end face gas film pressure control equation of the dry gas seal is: .

[0054] In the formula, p is the pressure, r is the spiral groove radius, u is the gas viscosity, S t is the mass flow rate of the gas through the sealing end face, R is the gas constant, T is the gas temperature, h is the gas film thickness, w is the sealing ring rotation speed, h1 is the groove area gas film thickness, g1, g5 and g7 are the spiral groove coefficients.

[0055] According to the above control equation, the pressure at the micro spiral groove 101 at a specified speed can be calculated, and the opening force of the seal is determined. According to the calculation results of the above formula control equation, because the sealing end face is narrow (the spiral groove radius r is small, and the mass flow rate S t through the sealing end face is also small), the opening force generated by the micro spiral groove 101 is limited, which can be designed to be smaller than the sealing closing force, thereby ensuring the sealing of the dry running dynamic ring end face 74 and the static ring end face.

[0056] When in an ideal state, Figure 5The static ring 13 and the static ring seat 5 are shown in the normal clearance state. The static ring 13 and the static ring seat 5 are in concentric state. In the actual operation of the device, the shaft will be heat expanded due to the temperature change of the process medium, and the rotating shaft 21 will also tend to move back and forth in a small range along the axial direction due to the change of the first medium pressure and the bearing clearance, thereby driving the dynamic ring 7 fixed on the shaft sleeve 1 and the static ring 13 adhered to the dynamic ring to float along the axial direction. Due to the existence of the sixth gap (the normal clearance between the static ring 13 and the static ring seat 5) 133 and the seventh gap (the normal clearance between the static ring 13 and the static ring seat 5) 134, when the static ring 13 floats along the axial direction, the static ring seat 5 will not directly contact the static ring 13 to interfere with the floating of the static ring 13.

[0057] As shown in Figure 6 the actual application, the static ring 13 and the static ring seat 5 are not concentric as in the ideal state due to the influence of the device accuracy, the installation accuracy and the connection accuracy between the parts, and the static ring seat 5 and the axis line 19 generally have an included angle a. In order to conveniently show the included angle a, Figure 6 a first auxiliary line 191 parallel to the axis line 19 is added, that is, there is an included angle a between the static ring seat 5 and the first auxiliary line 191. At this time, the sizes of the sixth gap 133 and the seventh gap 134 are not uniform. Since the sixth gap 133 and the seventh gap 134 are macroscopic gaps controlled by size, although the static ring 13 and the static ring seat 5 have the included angle a, they do not interfere with each other, and the static ring 13 can move left and right along the axis in the static ring seat 5.

[0058] When in the ideal state, Figure 7 The dynamic ring 7 and the shaft sleeve 1 are shown in the normal clearance state. The dynamic ring 7 and the shaft sleeve 1 are in concentric state. In the actual operation of the device, the shaft will be heat expanded due to the temperature change of the process medium, and the rotating shaft 21 will also tend to move back and forth in a small range along the axial direction due to the change of the second medium pressure and the bearing clearance, thereby driving the dynamic ring 7 fixed on the shaft sleeve 1 to float along the axial direction. At this time, due to the existence of the third gap 73 between the dynamic ring 7 and the shaft sleeve 1, when the dynamic ring 7 floats along the axial direction, the dynamic ring 7 will not directly contact the shaft sleeve 1 to interfere with the floating of the dynamic ring 7.

[0059] As shown in Figure 8 the actual application, the dynamic ring 7 and the shaft sleeve 1 are not concentric as in the ideal state due to the influence of the device accuracy, the installation accuracy and the connection accuracy between the parts, and the shaft sleeve 1 and the axis line 19 generally have an included angle b. In order to conveniently show the included angle b, Figure 8A second auxiliary line 192 parallel to the axis 19 is added, meaning there is an angle b between the bushing 1 and the second auxiliary line 192. At this point, the size of the third gap 73 is not uniform. Since the third gap 73 is a macroscopic gap controlled by size, although there is an angle b between the moving ring 7 and the bushing 1, the moving ring 7 and the bushing 1 do not interfere with each other, and the moving ring 7 can float axially on the bushing 1. Due to the bidirectional balanced axial force and the bidirectional floating characteristics of the moving ring 7 and the stationary ring 13, the moving ring 7 and the stationary ring 13 can always maintain a close fit, ensuring that the seal is not affected even if the equipment has a slight sway (the sway does not exceed the sealing design range).

[0060] The microgroove 41 of the present invention includes a unidirectional microgroove 75 and a bidirectional microgroove 78. For example... Figure 9 As shown, the moving ring 7 mates with the stationary ring 13, and multiple uniformly distributed unidirectional micro-grooves 75 are engraved on the end face 74 of the moving ring. The minor diameter D1 of the unidirectional micro-grooves 75 is smaller than the inner diameter d1 of the end face of the stationary ring, to ensure that the gas inside the moving ring 76 can enter the unidirectional micro-grooves 75. Here, the minor diameter refers to the diameter of the circular trajectory formed by the inner edge of the unidirectional micro-grooves 75 (i.e., the diameter of the unidirectional micro-grooves 75 on the side closer to the center of the moving ring 7), which is opposite to the outer diameter of the unidirectional micro-grooves 75 (the diameter of the unidirectional micro-grooves 75 on the side farther from the center), and is a key dimensional parameter for controlling the gas flow path.

[0061] The outer diameter D2 of the unidirectional microgroove 75 is smaller than the outer diameter d2 of the stationary ring end face to ensure that the gas inside the moving ring 76 cannot directly enter the outside of the moving ring 77 through the unidirectional microgroove 75. Figure 9 As shown, when the moving ring 7 is in Figure 9 When the device rotates clockwise, the one-way micro-groove 75 will transport the gas inside the rotating ring 76 to the outer diameter of the one-way micro-groove 75. Since the stationary ring 13 is in contact with the rotating ring 7, and the outer diameter D2 of the one-way micro-groove 75 is smaller than the outer diameter d2 of the stationary ring end face, the gas will be compressed in the one-way micro-groove 75. At this time, the gas pressure in the one-way micro-groove 75 will rise, and the pressure will reach its maximum at the outer diameter D2 of the one-way micro-groove 75. This pressure will cause the rotating ring 7 and the stationary ring 13 to tend to open, which can reduce the wear of the sealing end face.

[0062] because Figure 9 The unidirectional microgroove 75 shown is only suitable for unidirectional rotation of the equipment. When bidirectional rotation of the equipment is possible, the dynamic pressure groove (end face groove) can be designed as a bidirectional microgroove 78, such as... Figure 10 As shown, the end face 74 of the moving ring 7, which mates with the stationary ring 13, is engraved with multiple uniformly distributed bidirectional microgrooves 78. (See figure) Figure 10As shown, the bidirectional micro groove 78 includes at least two pairs of symmetrically arranged arc grooves. The junctions of the arc grooves are provided with radial grooves along the radial direction. Preferably, the groove width of the arc grooves gradually narrows along the rotation direction. The outer diameter D3 of the bidirectional micro groove 78 is smaller than the outer diameter d3 of the static ring end face, and the inner diameter D4 of the bidirectional micro groove 78 is smaller than the inner diameter d4 of the static ring end face, so as to ensure that the gas in the inner side 76 of the dynamic ring cannot directly enter the outer side 77 of the dynamic ring through the bidirectional micro groove 78. That is, the radial range of the bidirectional micro groove 78 is between the inner diameter and the outer diameter of the static ring end face.

[0063] As shown in Figure 10 , when the dynamic ring 7 rotates along any rotation direction with the device (see the bidirectional rotation arrow in Figure 10 ), the bidirectional micro groove 78 will transport the gas in the inner side 76 of the dynamic ring to the outer diameter direction of the bidirectional micro groove 78. Since the static ring 13 is in close contact with the dynamic ring 7, and the outer diameter D3 of the bidirectional micro groove 78 is smaller than the outer diameter d3 of the static ring end face, the gas will be compressed in the bidirectional micro groove 78, at this time the gas pressure in the bidirectional micro groove 78 rises, and the pressure reaches the highest at the outer diameter D3 of the bidirectional micro groove 78. This pressure makes the dynamic ring 7 and the static ring 13 tend to open, which can reduce the wear of the sealing end face. The calculation of the pressure value at the outer diameter D2 of the unidirectional micro groove 75 and the outer diameter D3 of the bidirectional micro groove 78 is extremely complex, and is related to parameters such as spiral groove angle, depth, gas viscosity, angular velocity, etc. Under the condition that other parameters are equal, the pressure at the outer diameter D2 of the unidirectional micro groove 75 is proportional to the area of the unidirectional micro groove 75, and the pressure at the outer diameter D3 of the bidirectional micro groove 78 is proportional to the area of the bidirectional micro groove 78. The width of the dry running seal static ring end face is narrower than the conventional dry gas seal, and the areas of the unidirectional micro groove 75 and the bidirectional micro groove 78 are also much smaller than those of the conventional dry gas seal micro groove, so the dynamic pressure generated is limited. According to theoretical calculation, the opening force generated by this dynamic pressure is far less than the closing force of the seal, so the sealing end face of the dynamic ring 7 and the static ring 13 is still in contact state, the medium cannot leak into the sealing end face, and the gas cannot enter the medium, that is, the closing force between the sealing end face of the dynamic ring 7 and the static ring 13 in the sealing state is reduced, and the sealing property is maintained.

[0064] As shown in Figure 11 , during the operation of the dry running seal, the sealing end face of the dynamic ring 7 and the static ring 13 will be worn, and the gas in the dynamic ring side 207 will exchange heat with the dynamic ring 7 and the static ring 13, forming high-temperature gas (see the dashed line in Figure 11 , which refers to gas with a higher temperature than normal temperature gas). The shaft sleeve 1 is provided with uniformly distributed spiral grooves 101 on the outer side. When the shaft sleeve 1 rotates with the rotating shaft 21 in the shaft sleeve rotation direction 208 as shown, Figure 11 , the spiral grooves 101 will drive the gas in the spiral grooves 101 to the Figure 11The leftward flow (see high-temperature gas flow direction 206) transports the high-temperature gas on the moving ring side 207 to the atmospheric side 200 through the spiral groove 101; simultaneously, because the gas on the moving ring side 207 is transported to the atmospheric side 200, a slight negative pressure is formed on the moving ring side 207, and the room-temperature gas on the atmospheric side 200 (which is also a room-temperature and room-pressure gas, see...) Figure 11 The ambient temperature gas flow direction 205 shown will flow through the gap between the stationary ring seat 5 and the bushing 1 to the moving ring side 207. This forms a cycle, continuously transporting the high temperature gas from the moving ring side 207 to the atmospheric side 200. The ambient temperature gas from the atmospheric side 200 then replenishes the moving ring side 207, exchanging heat with the moving ring 7 and the stationary ring 13, carrying away the heat generated by the wear of the moving ring 7 and the stationary ring 13.

[0065] like Figure 11 As shown, the spiral groove 101 is limited by the direction of rotation and only supports unidirectional rotation. When the equipment can rotate in both directions, it can be selected as follows: Figure 12 The bushing has a bidirectional groove 102 shown on the left. The bidirectional groove 102 consists of multiple evenly distributed U-shaped grooves on the outer side of the bushing 1. When the bushing 1 rotates with the rotating shaft 21, the bidirectional groove 102 drives the gas inside to rotate as well, accelerating the flow of gas between the moving ring side 207 and the atmospheric side 200. This allows for more thorough heat exchange between the high-temperature gas on the moving ring side 207 and the ambient temperature gas on the atmospheric side 200, thus removing the heat generated by wear on the sealing surfaces of the moving ring 7 and the stationary ring 13.

[0066] Preferably, the spiral groove 101 enables more thorough exchange of cold / high-temperature gases. In the case of unidirectional rotation of the equipment, a unidirectional spiral groove is preferred.

[0067] like Figure 13 and Figure 14 As shown, multiple evenly distributed arc-shaped grooves 181 are machined on the drive sealing side 180 of the drive ring 18, i.e., the sealing-facing side of the drive ring 18. The arc-shaped grooves 181 extend radially outward from the inner diameter position of the drive ring 18, and the cross-sectional area of ​​the arc-shaped grooves 181 gradually increases with outward extension; that is, as the diameter increases, the cross-sectional length of the arc-shaped grooves 181 gradually increases from L2 to L1. A straight groove 182 is provided at the inner hole position of the drive ring 18. The straight groove 182 mills through the inner hole of the drive ring 18 and communicates with the arc-shaped grooves 181.

[0068] like Figure 14 As shown, when the drive ring 18 is pressed... Figure 14As the axis 21 rotates in the direction shown (see the unidirectional rotating arrow), due to the change in the cross-sectional area of ​​the arc-shaped groove 181, the arc-shaped groove 181 compresses the ambient temperature gas in the atmospheric environment 209 outside the drive ring 18 along the solid line shown in the figure (see the arrow inside the arc-shaped groove 181) and transports this ambient temperature gas to the inner diameter position of the drive ring 18. A portion of the ambient temperature gas flows through the straight groove 182 to the side 211 of the drive ring 18 facing away from the seal, i.e., the atmospheric environment 209. Another portion of the ambient temperature gas flows to the sealing side 210 of the moving ring 7 and the stationary ring 13, forming a linkage with the spiral groove 101 on the outside of the bushing 1, carrying away the high-temperature gas at the sealing end face, so that the high-temperature gas flows from the straight groove 182 to the atmospheric environment 209.

[0069] The arc-shaped groove 181 is designed to transport gas from the outside of the drive ring 18 to the inside of the drive ring 18, thereby enhancing heat exchange. When the direction of the arc-shaped groove 181 is opposite to the rotation direction of the equipment shaft, the gas flow direction in the arc-shaped groove 181 is reversed, with gas from the inside of the drive ring 18 being transported to the outside. This is detrimental to heat exchange in a sealed environment; therefore, the arc-shaped groove 181 is a unidirectional groove. When the equipment can rotate in both directions, a different type of groove can be selected. Figure 15 The drive ring 18 shows a bidirectional groove 183, which is evenly distributed on the sealing side (drive-seal side 180) of the drive ring 18. A straight groove 182 is provided in the inner hole of the drive ring 18, milling through the inner hole and communicating with the bidirectional groove 183. When the device rotates clockwise or counterclockwise, it can drive the gas flow in the drive-seal side 180 of the drive ring 18, enhancing the circulation of room temperature gas and high temperature gas. Preferably, while ensuring that the rotation direction of the device remains unchanged, the drive-seal side 180 of the drive ring 18 is preferably a unidirectional arc-shaped groove.

[0070] Figure 16 This is a schematic diagram showing the flow of gas under the influence of the arcuate groove 181 and straight groove 182 on the drive ring 18, the spiral groove 101 on the outer side of the bushing 1, and the unidirectional micro-groove 75 on the end face 74 of the moving ring. Figure 16As shown, the solid line is the flow direction of the normal temperature gas, and the dotted line is the flow direction of the high temperature gas after heat exchange with the sealing end faces of the dynamic ring 7 and the static ring 13. When the sealing rotating part rotates with the rotating shaft 21, the axial force generated by the rotation of the helical groove 101 outside the shaft sleeve 1 pushes the high temperature gas at the sealing end face to the atmospheric side 200, and the straight groove 182 in the inner hole of the driving ring 18 is arranged to the atmospheric environment 209. Since the high temperature gas at the sealing end face is driven by the helical groove 101 to flow to the atmosphere, at this time, the normal temperature gas outside the driving ring 18 flows to the inside under the action of the arc-shaped groove 181 of the driving ring 18. Between the static ring seat 5 and the shaft sleeve 1, part of the gas is pushed out to the atmospheric environment 209 together with the high temperature gas driven by the helical groove 101, and the other part flows to the sealing end face, is pushed out by the helical groove 101 after taking away the heat, and forms a cycle. This is the self-cooling mode of the sealing scheme. At the same time, part of the gas enters between the sealing end faces along the one-way micro groove 75 of the dynamic ring end face 74, and generates dynamic pressure between the end faces to reduce wear.

[0071] As shown in Figure 16 When the driving ring 18 and the shaft sleeve 1 rotate with the rotating shaft 21, the helical groove 101 formed on the driving ring 18 and the shaft sleeve 1 makes the high temperature gas at the inner hole position of the sealing end face flow to the atmospheric environment 209, and makes the cold gas in the atmospheric environment 209 flow to the sealing position to exchange heat. As shown in Figure 6 and Figure 8 When the static ring seat 5 or the shaft sleeve 1 is deflected, that is, when the rotating shaft 21 is at a deflection angle, the sealing can still ensure that the dynamic ring 7 and the static ring 13 are attached to the entire sealing end face, so that the sealing is always in a uniform wear state and maintains the sealing state.

[0072] In order to reduce the sealing wear and ensure the service life of the sealing, the sealing ring material of the dry running seal of the present application is suggested to be matched as follows: graphite vs silicon carbide, or graphite vs hard alloy. The dynamic ring 7 is a graphite ring with a narrow end face. The static ring 13 is a silicon carbide or hard alloy ring with a wide end face.

[0073] The width of the narrow ring end face of the sealing is in the range of 3-10 mm. Within this range, the micro groove 41 can generate dynamic pressure effect, and the sealing will not be largely worn due to the too wide end face. Preferably, the width of the narrow ring end face of the sealing is 7 mm, at which time, within a certain pressure range, the opening force generated by the micro groove 41 can offset about 40% of the closing force.

[0074] The sealing load coefficient K is in the range of 0.5-1.0, within which the sealing can effectively block the process medium. Preferably, the load coefficient K is 0.76, at which time, under the premise that the sealing effectively blocks the process medium, the closing force of the sealing is also moderate.

[0075] Example 2 This embodiment is a further improvement on embodiment 1, and repeated content will not be described again.

[0076] like Figure 17 As shown, this structure is a schematic diagram of another sealing structure that achieves the same function. Figure 17 and Figure 1 The difference lies in the transmission method and axial displacement limiting method of the moving ring 7. Figure 17 In the structure shown, a bushing step 24 is provided on the outer side of the bushing 1 to restrict the displacement of the moving ring 7 towards the atmosphere 200. A moving ring seat 22 is provided on the side of the moving ring 7 facing the medium. The moving ring seat 22 is restricted from displacement towards the medium side 201 by the first retaining ring 12. A cylindrical pin 3 is provided on the outer side of the bushing 1. One end of the cylindrical pin 3 is fixed to the bushing 1, and the other end extends into the pin groove of the moving ring 7, so that the moving ring 7 can rotate together with the bushing 1. Figure 17 With Figure 1 The difference in the structure shown is that, Figure 17 The structure shown has an additional moving ring seat 22, but the moving ring 7 and bushing 1 are simpler, reducing the processing difficulty and material consumption. This structure can be selected when cost reduction is a consideration.

[0077] like Figure 18 As shown, this structure is a schematic diagram of another sealing structure that achieves the same function. Figure 18 and Figure 1 The difference is that the stationary ring 13 is made of a rigid material and is located inside the stationary ring seat 5. A fourth O-ring 15 is installed in the groove at the outer diameter of the stationary ring 13, that is, the outer circumference of the stationary ring 13 has an O-ring mounting groove, and the fourth O-ring 15 is installed in it, so that the first medium pressure only acts on the side of the stationary ring 13 facing the medium. Multiple evenly distributed cylindrical springs (second elastic elements 17) are installed between the side of the stationary ring 13 facing the atmosphere and the stationary ring seat 5 to provide static elastic force for the stationary ring 13 to counteract the second medium pressure and dynamic elastic force of the moving ring 7. Therefore, the static elastic force of the second elastic element 17 on the back of the stationary ring 13 in this structure is greater.

[0078] Preferably, Figure 18In the embodiment, the dynamic ring 7 is made of soft material and is arranged in the dynamic ring seat 22. The dynamic ring seat 22 is fixed to the outside of the shaft sleeve 1 by the set screw 2. The second push ring 38 and the fifth O-shaped ring 39 are arranged between the dynamic ring 7 and the dynamic ring seat 22. The third elastic element 40 is arranged between the second push ring 38 and the dynamic ring seat 22. Preferably, the third elastic element 40 is a cylindrical spring. The third elastic element 40 pushes the second push ring 38 to provide the floating force for the dynamic ring 7 and presses the fifth O-shaped ring 39, so that the fifth O-shaped ring 39 is always in contact with the dynamic ring 7 and floats with the dynamic ring 7. Since the second elastic element 17 at the back of the static ring 13 does not contact the medium, when there is material in the medium that may block the spring, the second elastic element 17 at the back of the static ring 13 can ensure that it is not blocked. When the third elastic element 40 at the back of the dynamic ring 7 is blocked so that the dynamic ring 7 loses the floating property, the axial force of the medium on the dynamic ring 7 and the dynamic elastic force at the back of the dynamic ring 7 will not be transmitted to the static ring 13, so that the second elastic element 17 at the back of the static ring 13 applies the static elastic force to the static ring 13 in the axial direction. After the effect of the second medium pressure is offset, the static ring 13 can still provide greater floating force, so that the sealing end faces of the dynamic ring 7 and the static ring 13 can still be in contact.

[0079] Embodiment 3 In order to compare the actual wear-reducing and cooling effects of various parameters, an experimental tool for this scheme is used, as shown in Figure 19 The sealing assembly is connected to the test bench and forms a simulated medium chamber through the tool connecting disc 26, the tool sealing cavity 27 and the auxiliary sealing ring. The test bench motor side 212 is provided with a test bench support 25. The tool sealing cavity 27 is provided with a GBI interface 28. The GBI interface 28 is a gas injection interface. During the test, simulated medium is introduced into the simulated medium chamber. When the test is carried out, the sealing wear amount and the sealing ring temperature rise are detected for comparison. The specific detection method is as follows: 1. Wear amount: the thickness difference of the graphite ring before and after the test is measured by a vertical optical comparator to calculate the wear amount of the graphite ring; 2. Sealing ring temperature: a temperature sensor is bonded to the static ring 13. The lead wire 33 is connected to the corresponding transmitter after passing through the temperature sensor connecting port 32 provided on the tool connecting disc 26. The temperature sensor connecting port 32 is blocked by a special plug. The temperature sensor is close to the sealing end face and can accurately measure the temperature at the sealing end face in time. The cooling effect of various structural parameters on the friction heat of the sealing end face can be accurately judged through temperature monitoring.

[0080] Through the tool shown in Figure 19 , a sealing assembly of a certain shaft diameter is selected for comparison test. The working condition is: pressure 0.2 MPa, rotating speed 3000 rpm. The comparison results are shown in Table 2.

[0081] Table 2: Comparison of heat exchange effects of the helical grooves 101 on the driving ring 18 and the shaft sleeve 1

[0082] As can be seen from Table 2, when the driving ring 18 and the shaft sleeve 1 have the helical groove 101, the static ring wear and temperature rise are obviously reduced, wherein the static ring wear is reduced by 12%, and the static ring temperature rise is reduced by 22.7%.

[0083] Table 3: Comparison of whether the dynamic ring end face 74 is provided with the one-way micro groove 75

[0084] As can be seen from Table 3, when the dynamic ring end face 74 is designed to have the one-way micro groove 75, the static ring wear and temperature rise are obviously reduced, wherein the static ring wear is reduced by 59.5%, and the static ring temperature rise is reduced by 48.5%.

[0085] The depth of the one-way micro groove 75 is in the range of 5-20 um. The preferred value of the depth of the one-way micro groove 75 is 8 um, and at this time, the sealing dynamic pressure effect is stronger.

[0086] Table 4: Comparison of whether the dynamic ring 7 back has the third elastic member 40

[0087] As can be seen from Table 4, when the dynamic ring 7 back is designed to have the third elastic member 40, the static ring wear and temperature rise are obviously reduced, wherein the static ring wear is reduced by 26.5%, and the static ring temperature rise is reduced by 26%.

[0088] Table 5: Comparison of whether the dynamic ring 7 back has the third elastic member 40 when the rotating shaft 21 is deflected

[0089] As can be seen from Table 5, when the rotating shaft 21 is deflected, when the dynamic ring 7 back is designed to have the third elastic member 40, the static ring wear and temperature rise are obviously reduced, wherein the static ring wear is reduced by 78.6%, and the static ring temperature rise is reduced by 46.9%.

[0090] As described above, through the above comparison test, it can be proved that this structure has obvious low wear and low temperature rise advantages in high-speed working conditions or poor equipment precision, and can greatly improve the service life of the seal.

[0091] It should be noted that the above-mentioned embodiments illustrate rather than limit the application, and that those skilled in the art will be able to devise modifications which, though perhaps not explicitly described or shown herein, nonetheless fall within the scope of the application. Accordingly, the patent application includes all modifications encompassed within the scope of the claims and their equivalents. The patent application contains several inventive concepts, and the applicant reserves the right to file separate applications on each of these concepts, or on any combination or sub-combination of these concepts.

Claims

1. A self-cooled anti-eccentricity double-floating dry-running seal, comprising a shaft sleeve (1), a dynamic ring (7) and a static ring (13), the dynamic ring (7) is arranged outside the shaft sleeve (1), and the dynamic ring (7) and the shaft sleeve (1) are driven by a yoke; the static ring (13) is arranged in the cavity of a static ring seat (5); characterized in that, a first elastic member (10) is arranged on the side of the dynamic ring (7) away from the static ring (13), so that the dynamic ring (7) floats axially relative to the shaft sleeve (1); at least one second elastic member (17) is arranged in the cavity of the static ring seat (5), the second elastic member (17) is connected with a first push ring (16), and the first push ring (16) is tightly attached to the side of the static ring (13) away from the dynamic ring (7) through a fourth O-ring (15), so that the first push ring (16) and the fourth O-ring (15) always float with the static ring (13); the side of the static ring (13) away from the dynamic ring (7) is subjected to a static elastic force and a first medium pressure applied by the second elastic member (17), and the side of the dynamic ring (7) away from the static ring (13) is subjected to a dynamic elastic force and a second medium pressure applied by the first elastic member (10); under the axial dynamic action of the static elastic force, the first medium pressure, the dynamic elastic force and the second medium pressure, in the process that the dynamic ring (7) and the static ring (13) are converted from a non-equilibrium state to an equilibrium state, the sealing end faces of the dynamic ring (7) and the static ring (13) can always be in contact and kept in close contact, and bidirectional floating is achieved in the axial direction.

2. The dry running seal of claim 1, wherein, the static ring (13) is in a concentric state with the step in the cavity of the static ring seat (5); there are a first gap (71) and a second gap (72) between the static ring (13) and the static ring seat (5), so that when the static ring (13) floats in the axial direction of the rotating shaft (21), the static ring seat (5) does not directly contact the static ring (13) and does not interfere with the floating of the static ring (13).

3. Dry-running seal according to claim 1 or 2, characterized in that the dynamic ring (7) is in a concentric state with the shaft sleeve (1); there is a third gap (73) between the dynamic ring (7) and the shaft sleeve (1), when the dynamic ring (7) floats in the axial direction, the dynamic ring (7) does not directly contact the shaft sleeve (1) and does not interfere with the floating of the dynamic ring (7).

4. The dry-seal of any of claims 1-3, wherein, a plurality of one-way micro grooves (75) are arranged on the dynamic ring end face (74) of the dynamic ring (7) matched with the static ring (13), the small diameter of the one-way micro groove (75) is smaller than the inner diameter of the static ring end face, so as to ensure that the gas on the inner side of the dynamic ring (76) can enter the one-way micro groove (75); the outer diameter of the one-way micro groove (75) is smaller than the outer diameter of the static ring end face, so as to ensure that the gas on the inner side of the dynamic ring (76) cannot directly enter the outer side of the dynamic ring (77) through the one-way micro groove (75).

5. The dry-seal of any of claims 1-3, wherein, a plurality of two-way micro grooves (78) are arranged on the dynamic ring end face (74) of the dynamic ring (7) matched with the static ring (13), the outer diameter of the two-way micro groove (78) is smaller than the outer diameter of the static ring end face, and the inner diameter of the two-way micro groove (78) is smaller than the inner diameter of the static ring end face, so as to ensure that the gas on the inner side of the dynamic ring (76) cannot directly enter the outer side of the dynamic ring (77) through the two-way micro groove (78).

6. The dry-seal of any of claims 1-5, wherein, The outer side of the shaft sleeve (1) is provided with uniformly distributed spiral grooves (101), When the shaft sleeve (1) rotates with the rotating shaft (21), the spiral grooves (101) will drive the gas in the spiral grooves (101) to flow along the grooves, and the high-temperature gas on the dynamic ring side (207) is transported to the atmospheric side (200) through the spiral grooves (101), the dynamic ring side (207) forms a slight negative pressure, and the normal-temperature gas on the atmospheric side (200) flows to the dynamic ring side (207) through the gap between the static ring seat (5) and the shaft sleeve (1), thereby forming a circulation; The high-temperature gas on the dynamic ring side (207) is continuously transported to the atmospheric side (200), and the normal-temperature gas on the atmospheric side (200) is supplemented to the dynamic ring side (207) and exchanges heat with the dynamic ring (7) and the static ring (13), thereby taking away the heat generated by the wear of the dynamic ring (7) and the static ring (13).

7. The dry-seal of any of claims 1-6, wherein, The outer side of the shaft sleeve (1) is provided with a plurality of shaft sleeve bidirectional grooves (102), When the shaft sleeve (1) rotates with the rotating shaft (21), the shaft sleeve bidirectional grooves (102) drive the gas in the shaft sleeve bidirectional grooves (102) to rotate together, accelerate the flow of the gas on the dynamic ring side (207) and the atmospheric side (200), and make the heat exchange of the high-temperature gas on the dynamic ring side (207) and the normal-temperature gas on the atmospheric side (200) more sufficient, so as to take away the heat generated by the wear of the end faces of the dynamic ring (7) and the static ring (13).

8. The dry-seal of any of claims 1-7, wherein, Further comprising a driving ring (18), The driving ring (18) is connected with the shaft sleeve (1) and fixed on the rotating shaft (21), so that it can rotate with the rotating shaft (21); The driving sealing side (180) of the driving ring (18) facing the seal is provided with a plurality of arc grooves (181); The arc grooves (181) extend outward from the inner diameter position of the driving ring (18) in the radial direction of the rotating shaft (21), and the cross-sectional area of the arc grooves (181) in the circumferential direction gradually increases with the outward extension, The inner hole position of the driving ring (18) is provided with a straight groove (182), and the straight groove (182) mills through the inner hole of the driving ring (18) and communicates with the arc grooves (181); When the driving ring (18) rotates with the rotating shaft (21), the arc grooves (181) compress the normal-temperature gas in the atmospheric environment (209) outside the driving ring (18) and transport these normal-temperature gas to the inner diameter position of the driving ring (18), part of the normal-temperature gas flows to the atmospheric environment (209) on the side (211) of the driving ring (18) away from the seal through the straight groove (182); another part of the normal-temperature gas flows to the sealing side (210) of the dynamic ring (7) and the static ring (13), and forms linkage with the spiral grooves (101) on the outer side of the shaft sleeve (1), takes away the high-temperature gas on the sealing end face position, and makes the high-temperature gas flow from the straight groove (182) to the atmospheric environment (209).

9. The dry-seal of any of claims 1-8, wherein, The outer side of the shaft sleeve (1) is provided with a shaft sleeve step (24) for limiting the displacement of the dynamic ring (7) to the atmospheric side (200), A dynamic ring seat (22) is arranged on the side of the dynamic ring (7) facing the medium, and the dynamic ring seat (22) is limited to displace to the medium side (201) by the first clamping ring (12); A cylindrical pin (3) is arranged outside the shaft sleeve (1), one end of the cylindrical pin (3) is fixed on the shaft sleeve (1), the other end extends into the pin slot of the movable ring (7), so that the movable ring (7) can rotate with the shaft sleeve (1).

10. The dry-seal of any of claims 1-9, wherein, An O-ring is arranged in the groove at the outer diameter of the static ring (13) made of hard material, so that the first medium pressure only acts on the side of the static ring (13) facing the medium; The movable ring (7) made of soft material is arranged in the movable ring seat (22), the movable ring seat (22) is fixed outside the shaft sleeve (1) through the set screw (2), and the second push ring (38) and the fifth O-ring (39) are arranged between the movable ring (7) and the movable ring seat (22).

Images