A composite structure of screw seal and magnetic fluid seal and high-speed rotor with the same

Abstract

The present application belongs to the technical field of mechanical transmission sealing, and particularly relates to a spiral sealing and magnetic fluid sealing composite structure and a high-speed rotor with the same. The present application utilizes the high-speed pumping backflow characteristic of the spiral sealing and the static zero leakage characteristic of the magnetic fluid sealing to complement each other, and realizes full working condition sealing from zero rotation speed to the highest rotation speed. When the gear box rotor is static or operates at low speed, the magnetic fluid sealing unit relies on the magnetic field to constrain the magnetic fluid to occupy the sealing gap, and realizes static sealing; when the gear box rotor reaches a certain rotation speed, the lubricating oil is pumped back to the inside of the box body in reverse through the back oil channel through the pumping action of the spiral groove of the spiral sealing, and dynamic sealing is realized; the spiral sealing bears most of the sealing pressure difference, so that the magnetic fluid sealing unit only bears very low pressure difference, thereby allowing the magnetic fluid sealing to still maintain a sealing form under high-speed rotation.

Description

Technical Field

[0001] This invention belongs to the field of mechanical transmission sealing technology, specifically relating to a composite structure of spiral seal and magnetohydrodynamic seal and a high-speed rotor with the structure. Background Technology

[0002] High-speed gearboxes, as the most commonly used power transmission devices in modern industrial production, are widely used due to their advantages such as compact structure, high transmission efficiency, smooth operation, high reliability, long service life, and low cost. The gearbox relies on lubricating oil to adequately lubricate and cool the gear pairs and bearings. However, during high-speed operation, the lubricating oil inside the gearbox forms a large amount of oil mist under the high-speed agitation of the gears, significantly increasing the oil pressure and temperature at the shaft end seals. Under these conditions, if the sealing system fails, lubricating oil leakage will occur, causing not only insufficient lubrication and premature wear of gears and bearings, but also polluting the external environment. In severe cases, it can lead to equipment shutdown or even safety accidents. Therefore, the reliability of the sealing structure directly affects the operational safety and service life of the high-speed gearbox.

[0003] Currently, high-speed gearbox shaft end seals mainly employ structures such as skeleton oil seals, mechanical seals, and labyrinth seals. However, each of these existing sealing structures has its own inherent defects. Skeleton oil seals are contact seals, where the rubber sealing lip directly rubs against the journal surface under high-speed rotation. This not only generates a large amount of frictional heat, but the rubber material is also prone to wear and aging under complex operating conditions such as high speed and large temperature differences, leading to a rapid decline in sealing performance and requiring frequent replacement, which seriously affects the equipment's operation and maintenance efficiency and economy. Mechanical seals, while possessing good sealing performance, have extremely high requirements for installation accuracy, shaft coaxiality, and lubrication conditions. In operating environments with frequent equipment start-ups and shutdowns, speed changes, shaft vibrations, and severe temperature fluctuations, they are prone to dry friction, thermal deformation, and even seal failure, making it difficult to achieve long-term stable operation. Labyrinth seals, as non-contact seals, are widely used due to their simple structure and high-speed resistance. However, their principle of achieving sealing through throttling gaps means that leakage is difficult to completely eliminate, especially their limited ability to seal against splashed lubricating oil and oil mist inside the gearbox, making it impossible to achieve zero leakage.

[0004] During the high-speed rotation of the gearbox, the labyrinth seal rotor structure deforms due to centrifugal effect. Simultaneously, internal heating causes thermal expansion and deformation of the sealing structure. Centrifugal deformation and thermal expansion directly alter the sealing gap size, severely impacting the sealing performance of the sealing system. Furthermore, the trend towards larger power units continues, with gearbox speeds and power increasing daily, and shaft end linear velocities constantly rising. This places higher demands on the high-speed resistance of the sealing structure, making the performance bottlenecks of existing single-seal forms increasingly apparent.

[0005] In summary, there is an urgent need to develop a dynamic-static composite sealing structure suitable for high-speed gearbox rotors, which can maintain good sealing performance during start-up and across the entire speed range, and also features low leakage rate and long service life. This structure is intended to address the problems of insufficient sealing performance and poor reliability of existing sealing technologies under complex operating conditions. Summary of the Invention

[0006] The purpose of this invention is to provide a composite structure of spiral seal and magnetohydrodynamic seal, including a magnetohydrodynamic sealing unit and a spiral seal element; The magnetic fluid sealing unit includes a positioning sleeve, a sealing end cap, and a first magnetic pole, a permanent magnet, and a second magnetic pole located between the two. The permanent magnet is axially clamped between the first magnetic pole and the second magnetic pole. Gaps are left between the permanent magnet and the sealing end cap and the positioning sleeve. The first magnetic pole and the second magnetic pole are sealed with the sealing end cap by a first sealing ring. A sealing gap is reserved between the first magnetic pole and the second magnetic pole and the positioning sleeve, and magnetic fluid is filled in the sealing gap. The spiral seal is a cylindrical rotating shell part with a spiral groove machined on the inner circle and an annular sealing lip structure at the end. The spiral seal is integrally sleeved on the outside of the positioning sleeve, and the spiral seal and the positioning sleeve are sealed by a second sealing ring. The end of the spiral seal is constrained within the stepped end face on the outside of the sealing end cover.

[0007] Furthermore, a retaining ring is provided between the first magnetic pole and the sealing end cover. One side of the retaining ring abuts against the stepped surface of the inner cavity of the sealing end cover, and the other side is in close contact with the first magnetic pole.

[0008] Furthermore, the magnetic fluid sealing unit also includes a pressure plate fixed on the sealing end cover, which, together with the retaining ring, axially positions the first magnetic pole, the permanent magnet, and the second magnetic pole.

[0009] Furthermore, the first sealing ring is an O-ring.

[0010] Furthermore, the second sealing ring is a rubber sealing ring.

[0011] Furthermore, the sealing gap between the first and second magnetic poles and the positioning sleeve is 0.05~0.3mm.

[0012] The present invention also provides a high-speed rotor with a composite structure of helical seal and magnetohydrodynamic seal, including a gearbox rotor, an oil injection ring and a housing; the gearbox rotor is mounted on the housing via a support bearing, and the oil injection ring is mounted on the inner side of the support bearing; The spiral seal and the positioning sleeve are sequentially fitted onto the gearbox rotor, both located outside the support bearing; the sealing end cover is fixed to the housing; an oil return channel is provided on the housing, and the oil return channel communicates with the spiral groove of the spiral seal.

[0013] Furthermore, when the gearbox rotor is stationary or running at low speed, the magnetic fluid sealing unit relies on the magnetic field to constrain the magnetic fluid to occupy the sealing gap, thus achieving static sealing.

[0014] Furthermore, when the gearbox rotor reaches a certain speed, the lubricating oil is pumped back into the gearbox through the pumping action of the spiral groove of the spiral seal, thus achieving dynamic sealing.

[0015] Furthermore, the spiral groove of the spiral seal rotates in the opposite direction to the rotation direction of the gearbox rotor, so as to generate a pumping direction toward the inside of the gearbox.

[0016] The beneficial effects of this invention are as follows: (1) Full speed range sealing: This invention utilizes the high-speed pumping backflow characteristics of the spiral seal and the static zero leakage characteristics of the magnetic fluid seal to achieve full-condition sealing from zero speed to the highest speed, solving the problems of large oil leakage during the start-up and shutdown phase of the single spiral seal and high-speed centrifugal instability of the single magnetic fluid seal.

[0017] (2) Significantly improve the pressure and speed resistance of the magnetic fluid seal; In this invention, the spiral seal bears most of the sealing pressure difference, so that the magnetic fluid sealing unit only bears a very low pressure difference, thereby allowing the magnetic fluid seal to maintain a stable sealing shape under high-speed rotation.

[0018] (3) Extend service life; In this invention, the magnetic fluid sealing unit has a small pressure difference and no high-speed friction wear. The magnetic fluid is not easily oxidized and volatilized at high temperature, which significantly improves the service life. The spiral seal is a non-contact, wear-free component, with high overall reliability and long maintenance cycle.

[0019] (4) The structure is compact and basically does not increase the axial length. The present invention directly processes the spiral groove on the spiral seal, and the magnetic fluid sealing unit is arranged close to each other with only one isolation cavity in the middle. The total length increment is small and it is easy to modify the existing gearbox.

[0020] (5) Strong adaptability; the present invention can adjust the pumping capacity by changing the parameters of the spiral sealing groove (groove depth, pitch, number of heads), match different speeds, pressures and medium viscosities, and the cooling channel can effectively control the working temperature of the magnetic fluid, which is suitable for high temperature or large temperature difference conditions.

[0021] The spiral seal and magnetohydrodynamic seal composite structure and the high-speed rotor with the structure provided by this invention are particularly suitable for industrial equipment with stringent requirements for sealing performance, reliability and service life, such as high-speed gearboxes and high-speed turbine compressors. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of a high-speed rotor with a composite structure of helical seal and magnetohydrodynamic seal.

[0023] Figure 2 This is a schematic diagram of the spiral seal.

[0024] Figure 3 This is a schematic diagram of the magnetohydrodynamic sealing unit. Detailed Implementation

[0025] The present invention will now be further described with reference to the accompanying drawings.

[0026] Example 1: In existing technologies, magnetohydrodynamic (MHD) seals suffer from problems such as easy detachment and failure under high-speed centrifugal force, and insufficient pressure resistance, while spiral seals lack effective sealing capability at low speeds or during start-up and shutdown. This invention provides a composite structure combining a spiral seal and a MHD seal to address the problems encountered when either MHD or spiral seals are used alone.

[0027] like Figure 3 As shown, a composite structure of spiral seal and magnetohydrodynamic seal includes a magnetohydrodynamic sealing unit 3 and a spiral seal 5.

[0028] The magnetic fluid sealing unit 3 includes a positioning sleeve 2, a sealing end cover 34, a pressure plate 38, a first magnetic pole 32, a permanent magnet 35, and a second magnetic pole 36 located between the positioning sleeve 2 and the sealing end cover 34. The pressure plate 38 is fixed to the sealing end cover 34 by a second fastening bolt 37. The permanent magnet 35 is axially clamped between the first magnetic pole 32 and the second magnetic pole 36. A retaining ring 31 is provided between the first magnetic pole 32 and the sealing end cover 34. One side of the retaining ring 31 abuts against the inner cavity step surface of the sealing end cover 34, and the other side is tightly attached to the first magnetic pole 32. The pressure plate 38 and the retaining ring 31 axially position the first magnetic pole 32, the permanent magnet 35, and the second magnetic pole 36.

[0029] There are gaps between the permanent magnet 35, the sealing end cap 34, and the positioning sleeve 2. The first magnetic pole 32 and the second magnetic pole 36 are sealed with the sealing end cap 34 by the first sealing ring 33. The first sealing ring 33 can be an O-ring. A sealing gap is reserved between the first magnetic pole 32 and the second magnetic pole 36 and the positioning sleeve 2, and the sealing gap is filled with magnetic fluid 39.

[0030] The sealing gap between the first magnetic pole 32 and the second magnetic pole 36 and the positioning sleeve 2 is 0.05~0.3mm. The number of pole teeth of the first magnetic pole 32 and the second magnetic pole 36 can be single-stage or multi-stage (e.g., 2~6 stages), and the number of stages is determined according to the required pressure resistance level.

[0031] like Figure 2As shown, the spiral seal 5 is a cylindrical rotating shell part with a spiral groove machined on the inner circle and an annular sealing lip structure at the end. The spiral seal 5 is fitted onto the outside of the positioning sleeve 2. The spiral seal 5 and the positioning sleeve 2 are sealed by the second sealing ring 4. The second sealing ring 4 can be a rubber sealing ring. The end of the spiral seal 5 is constrained within the stepped end face on the outside of the sealing end cover 34.

[0032] The present invention provides a composite structure of spiral seal and magnetohydrodynamic seal, which includes both static seal and dynamic seal, and both contact seal and non-contact seal; the static seal adopts a second sealing ring 4 for contact sealing, and the dynamic seal adopts a spiral seal and magnetohydrodynamic seal, which is a non-contact seal.

[0033] Example 2: The present invention also provides a high-speed rotor with a composite structure of helical seal and magnetohydrodynamic seal, which can achieve zero leakage or extremely low leakage sealing of the rotor in the full speed range (including zero speed), while improving the high-speed adaptability and service life of the sealing system.

[0034] like Figure 1 As shown, a high-speed rotor with a composite structure of spiral seal and magnetohydrodynamic seal includes a gearbox rotor 1, an oil injection ring 9, and a housing 11. The gearbox rotor 1 is mounted on the housing 11 via a support bearing 8, and the oil injection ring 9 is mounted inside the support bearing 8. The support bearing 8, spiral seal 5, second sealing ring 4, and positioning sleeve 2 are mounted on the gearbox rotor 1 and are axially positioned by a second retaining ring 10. The oil injection ring 9 and the support bearing 8 are axially positioned by a first retaining ring 6. The sealing end cap 34 of the magnetohydrodynamic sealing unit 3 is mounted on the housing 11 via a first fastening bolt 7. An oil inlet channel and an oil return channel are provided on the housing 11. The oil inlet channel is connected to the oil injection ring 9, and the oil return channel is connected to the spiral groove of the spiral seal 5.

[0035] By fitting the spiral seal 5 with the sealing end cap 34, a non-contact spiral seal is formed. This sealing structure, as the first layer of seal, can effectively prevent lubricating oil leakage.

[0036] The static seal of the gearbox rotor 1 is formed by the installation and cooperation of the second sealing ring 4, the gearbox rotor 1, the spiral seal 5, and the positioning sleeve 2. This structure can effectively prevent lubricating oil from leaking out along the axis of the gearbox rotor.

[0037] When the gearbox rotor 1 is stationary or running at low speed, the magnetic fluid sealing unit 3 relies on the magnetic field to constrain the magnetic fluid 39 to occupy the sealing gap, thereby achieving static sealing and preventing lubricating oil leakage. At this time, the spiral seal pumping effect is weak and does not rely on its sealing.

[0038] When the gearbox rotor 1 reaches a certain speed, the spiral seal 5 pumps the leaking medium back into the housing under the pumping action of the spiral groove, achieving dynamic sealing and making the pressure of the intermediate isolation chamber close to the housing pressure, greatly reducing the pressure difference applied to both ends of the magnetic fluid sealing unit 3. The magnetic fluid sealing unit 3 works stably under low back pressure conditions, and because the pressure difference is small, the high-speed centrifugal force is not enough to cause the magnetic fluid 39 to be thrown off, thus simultaneously giving full play to the high speed adaptability of the spiral seal and the zero leakage characteristics of the magnetic fluid seal.

[0039] The spiral groove of the spiral seal 5 rotates in the opposite direction to the rotation direction of the gearbox rotor 1, so as to generate a pumping direction toward the inside of the housing 11. The spiral groove can be designed as rectangular, trapezoidal or triangular.

Claims

1. A composite structure of spiral seal and magnetohydrodynamic seal, characterized in that: Includes a magnetic fluid sealing unit (3) and a spiral seal (5); The magnetic fluid sealing unit (3) includes a positioning sleeve (2), a sealing end cap (34), and a first magnetic pole (32), a permanent magnet (35), and a second magnetic pole (36) located between the two. The permanent magnet (35) is axially clamped between the first magnetic pole (32) and the second magnetic pole (36). There are gaps between the permanent magnet (35) and the sealing end cap (34) and the positioning sleeve (2). The first magnetic pole (32) and the second magnetic pole (36) are sealed with the sealing end cap (34) through the first sealing ring (33). A sealing gap is reserved between the first magnetic pole (32) and the second magnetic pole (36) and the positioning sleeve (2). The sealing gap is filled with magnetic fluid (39). The spiral seal (5) is a cylindrical rotating shell part with a spiral groove machined on the inner circle and an annular sealing lip structure at the end. The spiral seal (5) is fitted on the outside of the positioning sleeve (2). The spiral seal (5) and the positioning sleeve (2) are sealed by the second sealing ring (4). The end of the spiral seal (5) is constrained within the stepped end face on the outside of the sealing end cover (34).

2. The composite structure of spiral seal and magnetohydrodynamic seal according to claim 1, characterized in that: A retaining ring (31) is provided between the first magnetic pole (32) and the sealing end cover (34). One side of the retaining ring (31) abuts against the inner cavity step surface of the sealing end cover (34), and the other side is in close contact with the first magnetic pole (32).

3. The composite structure of spiral seal and magnetohydrodynamic seal according to claim 2, characterized in that: The magnetic fluid sealing unit (3) also includes a pressure plate (38) fixed on the sealing end cover (34), which axially positions the first magnetic pole (32), the permanent magnet (35) and the second magnetic pole (36) through the pressure plate (38) and the retaining ring (31).

4. The composite structure of spiral seal and magnetohydrodynamic seal according to claim 1, characterized in that: The first sealing ring (33) is an O-ring.

5. The composite structure of spiral seal and magnetohydrodynamic seal according to claim 1, characterized in that: The second sealing ring (4) is a rubber sealing ring.

6. The composite structure of spiral seal and magnetohydrodynamic seal according to claim 1, characterized in that: The sealing gap between the first magnetic pole (32) and the second magnetic pole (36) and the positioning sleeve (2) is 0.05~0.3mm.

7. A high-speed rotor with the composite structure of helical seal and magnetohydrodynamic seal as described in claim 1, characterized in that: It includes a gearbox rotor (1), an oil injection ring (9), and a housing (11); the gearbox rotor (1) is mounted on the housing (11) via a support bearing (8), and the oil injection ring (9) is mounted inside the support bearing (8); The spiral seal (5) and the positioning sleeve (2) are sequentially fitted onto the gearbox rotor (1), both located outside the support bearing (8); the sealing end cap (34) is fixed to the housing (11); an oil return channel is provided on the housing (11), and the oil return channel is connected to the spiral groove of the spiral seal (5).

8. A high-speed rotor with a composite structure of helical seal and magnetohydrodynamic seal according to claim 7, characterized in that: When the gearbox rotor (1) is stationary or running at low speed, the magnetic fluid sealing unit (3) relies on the magnetic field to constrain the magnetic fluid (39) to occupy the sealing gap, thus achieving static sealing.

9. A high-speed rotor with a composite structure of helical seal and magnetohydrodynamic seal according to claim 7, characterized in that: When the gearbox rotor (1) reaches a certain speed, the lubricating oil is pumped back into the housing (11) through the pumping action of the spiral groove of the spiral seal (5), thereby achieving dynamic sealing.

10. A high-speed rotor with a composite structure of helical seal and magnetohydrodynamic seal according to claim 9, characterized in that: The spiral groove of the spiral seal (5) rotates in the opposite direction to the rotation direction of the gearbox rotor (1) to generate a pumping direction toward the inside of the housing (11).

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