Piston balanced high pressure rotary seal

Abstract

Piston balance type high pressure rotary sealing device, by hollow rotating shaft 1, bearing snap spring 2, bearing spacer ring 3, hollow plug 4, sealing plate 5, high pressure resistant filling grease 6, piston outer diameter sealing ring 7, end face sealing O ring 8, transmission medium outlet 9, bearing 10, shell 11, rotating shaft diameter surface sealing O ring 12, hollow piston 13, transmission medium inlet 14. Transmission medium is from 14 inlet to 9 outlet, hollow rotating shaft 1 and hollow piston 13 divide the right cavity of shell 11 into two, make the right side of piston 13 become transmission medium sealing cavity, left side become high pressure resistant grease 6 sealing cavity, thus form balanced rotary sealing to transmission medium, at the same time, utilize the poor flowing characteristic of high temperature resistant grease, carry out multi-stage combined variable contact pressure O ring rotary sealing.

Description

I. Technical Field

[0001] Piston-balanced high-pressure rotary seal device is suitable for high-pressure, high-speed rotary joints, high-pressure oil pump and water pump shafts, and mechanical rotating shafts such as propeller shafts. II. Technical Background

[0002] Rotary motion seals typically employ oil seals and mechanical seals. However, oil seals have lower operating pressures and are larger and more complex than O-rings, with poorer manufacturability. While mechanical seals can be used for high pressure, high speed, and high temperature applications, their structure is even more complex, bulky, and costly.

[0003] O-rings are used in rotary seals due to their simple structure, small size, low cost, and ease of maintenance. However, high rotational speeds generate frictional heat at the contact point between the O-ring and the shaft, and the greater the contact pressure and the higher the rotational speed, the more frictional heat is generated. This causes the O-ring to wear more quickly, age faster, and even fail and lose its seal under high pressure and high speed. Consequently, O-rings are unsuitable for high-speed and high-pressure transmission sealing in traditional rotary seal structures. III. Summary of the Invention

[0004] To ensure that O-rings meet the high-pressure, high-speed sealing requirements of rotary seals, our factory has designed and developed a piston-balanced high-pressure rotary seal device with O-rings as the basic rotary sealing element. It mainly consists of: a shell with an internal partition platform, a hollow rotating shaft, an O-ring, a hollow piston, bearings, a hollow plug, and a gasket-type sealing pressure plate. It employs the following novel sealing method and structure:

[0005] 1. A hollow piston divides the right cavity of the housing into two parts, making the cavity on the left side of the piston a high-temperature grease-filled sealing cavity, and the sealing cavity on the right side of the piston a sealing cavity for the transmission medium. This balances the pressure on both sides of the piston and the O-rings on both sides, thus forming a rotary seal for the transmission medium, primarily based on balanced isolation and secondarily on O-ring deformation isolation. This ensures that the pressure of the transmission medium does not exceed its limits, regardless of its pressure, while also preventing the O-rings used for rotary sealing at both ends of the piston from being squeezed out of their grooves. This ensures a rotary seal for the transmission medium while minimizing the contact pressure between the O-rings and the rotating shaft surface, minimizing wear, and minimizing frictional heat generation.

[0006] 2. Utilizing the extremely poor flowability and easy sealing properties of grease, a multi-stage combined automatic rotary seal of O-rings is applied to the left and right sides of the housing partition to distribute the contact pressure of the O-rings at the rotating surface. This ensures high-pressure sealing while minimizing the contact pressure of the O-rings on the rotating surface, minimizing wear, and minimizing frictional heat generation.

[0007] 3. By utilizing the combined variable cross-sectional area O-ring groove formed by the rotating shaft, sealing pressure plate, and stepped holes, the contact pressure between the O-ring and the radial surface of the rotating shaft is adjusted. This ensures that when the pressure of the transmitted medium is zero, the O-ring used for rotary sealing is in a free-floating state with no contact pressure, no wear, and minimal rotational resistance. When the transmitted medium generates pressure, the contact pressure of the O-ring at the rotating surface varies within a set range. This minimizes the contact pressure of the O-ring on the rotating surface, reduces frictional heat generation, and minimizes the ratio of wear to rotation time.

[0008] 4. Utilizing the characteristic that O-rings can rotate with the shaft and move axially by their own expansion force, the O-rings with combined variable cross-sectional area grooves are used for rotary sealing, and the sealing pressure plate forms an axially interlocked and squeezed end face rotary seal, thus forming a composite sealing structure that integrates multi-stage sealing, rotary sealing and end face sealing. IV. Description of the attached drawings

[0009] Figure 1 This is a schematic diagram of a hollow shaft piston-balanced high-pressure rotary seal device (rotary joint).

[0010] in:

[0011] 1 - Hollow Rotary Shaft

[0012] 2—Bearing snap ring

[0013] 3—Bearing spacer

[0014] 4 - Hollow blockage

[0015] 5 - Gasket-type sealing pressure plate

[0016] 6—High-temperature resistant filler grease

[0017] 7—Piston outer diameter seal ring

[0018] 8—End face sealing O-ring

[0019] 9—Transmission medium outlet

[0020] 10 - Bearings

[0021] 11 - Shell

[0022] 12—O-ring seal on the radial surface of the rotating shaft

[0023] 13 - Hollow Piston

[0024] 14—Transmission medium inlet V. Detailed Implementation Methods

[0025] Piston-balanced high-pressure rotary seals with O-rings as the basic rotary sealing element have various applications. For example, if such a seal is installed at one end of a hollow rotary shaft, with the transmission medium entering through the housing and exiting through the rotary shaft, it becomes a high-pressure rotary joint. If such a seal is installed on the housing at both ends of a hollow rotary shaft, with the space between the middle section of the rotary shaft and the housing serving as the transmission medium sealing cavity, it becomes a high-pressure seal for the rotary shaft of electromechanical equipment such as high-pressure water pumps or oil pumps.

[0026] The high-pressure rotary joint shown in the attached diagram consists of a hollow rotating shaft 1, a bearing retaining ring 2, a bearing spacer 3, a hollow plug 4, a gasket-type sealing plate 5, a high-temperature resistant filling grease 6, a hollow piston outer diameter sealing ring 7, two end face sealing O-rings 8, a transmission medium outlet 9, two bearings 10, a housing 11 with a partition inside the cavity, at least four O-rings for rotating shaft diameter sealing 12, a hollow piston 13, and a transmission medium inlet 14.

[0027] Bearing 10, spacer 3, and hollow plug 4 are disposed in the cavity on the left side of the partition of housing 11. Hollow piston 13 and gasket-type sealing plate 5 are disposed in the cavity on the right side of the partition of housing 11, and hollow rotating shaft 1 passes through its center and rotates freely.

[0028] The hollow piston 13 and the gasket-type sealing plate 5 divide the right cavity of the housing 11 into two parts, making the right end of the hollow piston 13 the sealing cavity for the transmission medium, and the left end of the hollow piston 13 the sealing cavity for the high-temperature resistant grease-filled 6. The outer diameter of the piston 13 is an O-ring seal with a constant groove cross-sectional area and a large compressibility. Cylindrical stepped holes 12 are provided on both sides of the inner bore of piston 13, with O-rings 12 placed in them respectively. The inner diameter of O-ring 12 is equal to the minimum outer diameter of rotating shaft 1, and the outer diameter of O-ring 12 is equal to the diameter of stepped hole of piston 13. However, the depth of stepped hole is less than the diameter of O-ring 12, resulting in a gap between the sealing pressure plate 5 on the outer side of O-ring 12 and the end faces of piston 13 on both sides. When there is no pressure, the O-ring is in a free floating state, thus forming two combined variable cross-sectional area O-ring grooves on the left and right sides, which are composed of the minimum shaft diameter surface of hollow rotating shaft 1, the stepped holes on both sides of piston 13, and sealing pressure plate 5. This forms a balanced rotary seal with O-ring 12, hollow piston 13, and sealing pressure plate 5 as the partition. Because piston 13 can move axially, when the transmission medium generates pressure, the high-temperature grease 6 generates the same pressure through piston 13, thereby balancing the pressure on both sides of piston 13 and O-ring 12. In this way, no matter how high the pressure of the transmission medium is, the O-ring 12 cannot be squeezed out of the groove, and the transmission medium and the high-temperature grease 6 cannot cross the boundary, thus completing the rotary seal of the transmission medium.

[0029] The primary rotary seal for the high-temperature grease, namely the rotary seal between the partition hole of the housing 11 and the rotating shaft 1, has the same structural principle as the seal between the piston 13 and the hollow rotating shaft 1, and is a combined variable cross-sectional area groove O-ring rotary seal. The rotary seal fixed in the left cavity of the partition of the housing 11, consisting of a hollow plug 4 and an O-ring 12, serves as an auxiliary seal for the high-temperature grease 6 and can be single-stage or multi-stage. The outer diameter of the plug 4 is equal to the diameter of the bearing 10. Its inner hole has a stepped hole (the diameter of the left section linearly decreases) formed by a series of cylindrical and frustum holes on the right side. The O-ring 12 is placed within this hole and can move axially. The inner diameter of the O-ring 12 is equal to the minimum diameter of the rotating shaft 1, and the outer diameter of the O-ring 12 is equal to the diameter of the cylindrical hole. This allows the O-ring 12 to float freely when not under pressure, and to move to the left when under pressure, causing its inner and outer diameters to be compressed, generating contact pressure and automatically forming an auxiliary rotary seal for the high-temperature grease 6.

[0030] To prevent impurities in the transmission medium from entering the rotating shaft diameter sealing surface and to increase the reliability of the rotary seal, O-rings with small cross-sectional diameters are installed before the sealing pressure plate 5 in the transmission medium sealing cavity and before the left sealing pressure plate 5 in the high-temperature grease sealing cavity. These O-rings are designed to rotate with the shaft due to their own expansion force and can also move slightly axially under the pressure of the medium. This creates contact pressure between the O-ring and the sealing pressure plate 5, forming an axially interlocked O-ring end-face seal. Therefore, this grooveless O-ring end-face rotary seal, combined with the combined variable cross-sectional area grooved O-ring shaft diameter rotary seal, forms a composite rotary seal structure that integrates multi-face sealing, rotating shaft diameter sealing, and end sealing into one unit.

[0031] In summary, in the piston-balanced high-pressure rotary sealing device, although the rotary shaft radial surface seal has many stages, its volume is small, and the contact pressure is diverted. The O-rings 12 are all stationary in the groove and use the inner diameter as the rotary sealing surface. Therefore, within the rated linear velocity range of the O-rings, the hollow rotary shaft 1 can obtain a large rotational speed.

[0032] The balanced sealing of the transmission medium makes it difficult for the O-rings 12 on both sides of the piston 13 to be squeezed out of the groove. Therefore, the maximum gap between the sealing pressure plate 5 and the end faces on both sides of the piston 13 can be set to be smaller, thereby reducing the maximum contact pressure, generating less frictional heat, and reducing wear.

[0033] For high-temperature resistant greases with extremely poor flowability, multi-stage O-ring combination sealing and composite sealing are used. Therefore, the maximum contact pressure value of the O-ring used for rotating shaft radial face sealing is not high, the average value is not large, wear is small, and the frictional heat generated is not much.

[0034] The O-ring 8, which is installed in front of the sealing pressure plate 5, serves as the primary seal to prevent impurities in the transmission medium from entering the rotating sealing surface of the shaft diameter. It also has a strong automatic compensation capability for wear at the contact point. Together with the O-ring rotating seal with a combined variable cross-sectional area groove, it forms a composite rotating seal structure with reliable sealing and strong complementarity.

[0035] When the pressure of the transmission medium is zero, the contact pressure is zero. When pressure is generated, the contact pressure changes accordingly, and the maximum value is not high, thus minimizing the ratio of the rotation time of the hollow shaft 1 to the wear rate of the O-ring 12.

Claims

1. A piston-balanced high-pressure rotary sealing device, using an O-ring as the basic rotary sealing element, characterized in that: The system includes a hollow rotating shaft (1), a bearing retaining ring (2), a bearing spacer (3), a hollow plug (4), three gasket-type sealing plates (5), a high-temperature resistant filling grease (6), a hollow piston outer diameter sealing ring (7), two end face sealing O-rings (8), a transmission medium outlet (9), two bearings (10), a housing (11), four rotating shaft diameter surface O-rings (12), a hollow piston (13), and a transmission medium inlet (14), wherein the two bearings (10) and the hollow plug (4) are located in... In the cavity on the left side of the partition of the housing (11), the hollow piston (13) and three sealing pressure plates (5) are placed in the cavity on the right side of the partition. The hollow rotating shaft (1) passes through its center and rotates freely. The hollow piston (13) divides the cavity on the right side of the partition of the housing (11) into two parts, so that the left side of the hollow piston (13) becomes a high-temperature resistant grease-filled sealing cavity and the right side becomes a transmission medium sealing cavity. Under the pressure of the transmission medium, the hollow piston (13) can move slightly along the axis, compressing the high-temperature resistant grease (6) to balance the pressure on both sides.

2. The piston-balanced high-pressure rotary sealing device according to claim 1, characterized in that: A rotary seal consisting of a hollow plug (4) and a rotating shaft diameter surface O-ring (12) is provided in the left cavity of the partition of the housing (11). The outer diameter of the hollow plug (4) is equal to the outer diameter of the bearing (10). The right section of the inner hole of the hollow plug (4) is provided with a stepped hole consisting of a cylindrical hole and a frustum hole connected in series. The diameter of the left section of the stepped hole decreases linearly. The rotating shaft diameter surface O-ring (12) is placed in it and can move axially. The variable diameter stepped hole where the rotating shaft diameter surface O-ring (12) is located and the minimum shaft diameter surface of the hollow rotating shaft (1) form a combined variable diameter O-ring groove.

3. The piston-balanced high-pressure rotary sealing device according to claim 1, characterized in that: An end-face sealing O-ring (8) is set in front of the gasket-type sealing pressure plate (5) in the sealing cavity of the transmission medium. It rotates with the hollow rotating shaft (1) by its own expansion force and can move axially, thereby forming a grooveless axial interlocking O-ring end-face rotary seal for the transmission medium.

4. The piston-balanced high-pressure rotary sealing device according to claim 1, characterized in that: An end-face sealing O-ring (8) is set in front of the gasket-type sealing pressure plate (5) on the left side of the high-temperature resistant grease sealing cavity. It rotates with the hollow rotating shaft (1) by its own expansion force and can move axially, thereby forming a grooveless axial interlocking O-ring end-face rotation seal for the high-temperature resistant grease.

5. The piston-balanced high-pressure rotary sealing device according to claim 1, characterized in that: Cylindrical stepped holes are provided on both sides of the inner hole of the hollow piston (13) and on the right side of the inner hole of the partition in the housing (11). These, together with the minimum outer diameter of the hollow rotating shaft (1) and the gasket-type sealing pressure plate (5), form three combined variable cross-sectional area O-ring sealing grooves. Rotating shaft diameter surface O-rings (12) are provided in each groove. The inner diameter of the rotating shaft diameter surface O-ring (12) in each groove is equal to the minimum diameter of the hollow rotating shaft (1), and the outer diameter is equal to the stepped hole diameter. The depth of the stepped hole is less than the diameter of the rotating shaft diameter surface O-ring (12). This results in a gap between the end faces of the three gasket-type sealing pressure plates (5) and their corresponding stepped holes when there is no axial pressure.

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