Mechanical seal end face structure for a medium liable to vaporization

Abstract

A mechanical seal end face structure for easy vaporization medium, comprising a dynamic ring and a static ring of a mechanical seal, the outer ring side of the sealing end face of the dynamic ring and the static ring is the high pressure side of the seal, namely the upstream, and the inner ring side of the sealing end face is the low pressure side of the seal, namely the downstream. The sealing end face of at least one of the dynamic ring and the static ring is sequentially distributed with a plurality of spiral grooves and a gas-liquid separation zone with micro convex bodies from the upstream to the downstream; the gas-liquid separation zone comprises a fan-shaped micro convex separation zone and a concentric circle micro convex separation zone; the adjacent concentric circle micro convex separation zones are separated by a concentric circle deep groove ring; the effect of sealing liquid by gas generated by vaporization is realized, multi-stage sealing of the spiral groove, the gas-liquid separation zone and the gas curtain is realized, and the wear rate of the sealing end face is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of mechanical seals, and in particular relates to a leakage-proof mechanical seal structure suitable for non-contact sealing of easily vaporized media. Background Art

[0002] In the aerospace industry, cryogenic propellants, primarily liquid hydrogen, liquid oxygen, and liquid methane, are the primary fuel for heavy-lift launch vehicles. Aerospace power plants rely on shaft seals to prevent the leakage of these cryogenic, easily vaporized, hazardous media. These seals seal the fluid by combining the end faces of a rotating rotor and a stationary rotor. Compared to traditional media, cryogenic media used in aerospace have lower viscosity and are more easily vaporized. Therefore, cryogenic media are highly susceptible to leakage through the seal faces under high pressure differentials, posing a significant challenge to the safe and reliable operation of critical power equipment. For example, in aerospace engines, after filling with cryogenic fuel and oxidizer, the turbopump is shut down. Under the pressure differential between the sealing media, the low-temperature, low-viscosity media is highly susceptible to leakage through the seal faces. This leakage process, coupled with a phase change due to the pressure drop, can cause the seal faces to open, leading to significant leakage and compromising the safety of the aerospace engine.

[0003] Invention publication number CN103470773B discloses a bird-wing-like multi-channel groove end-face seal structure. This design incorporates bird-wing-like drainage grooves on the sealing end face of the rotating ring of the shaft seal, providing both flow diversion and pressure stabilization functions. This design mitigates localized pressure on the seal end face due to media penetration. However, this design suffers from severe wear during high-speed operation, hindering stable operation of the equipment. Furthermore, it lacks gas-liquid separation capabilities, which can easily lead to localized accumulation of media, resulting in high pressure and subsequent leakage. Summary of the Invention

[0004] To address these issues, the present invention proposes a mechanical seal end face structure for easily vaporized media. Its design combines a micro-convex ring band to collect liquid with a concentric deep groove ring to form an air curtain. This improves airtightness while reducing wear on the mechanical seal end face, effectively achieving gas-liquid separation and thus suppressing and reducing leakage of low-viscosity, easily vaporized media from the mechanical seal end face.

[0005] A mechanical seal end face structure for easily vaporized media includes a dynamic ring and a static ring for the mechanical seal. The outer ring side of the sealing end face of the dynamic ring and the static ring is the high-pressure side of the seal, i.e., the upstream side, and the inner ring side of the sealing end face is the low-pressure side of the seal, i.e., the downstream side. The sealing end face 1 of at least one of the dynamic ring and the static ring is sequentially arranged from upstream to downstream with a plurality of spiral grooves 3 and a gas-liquid separation zone 2 with micro-protrusions 211. The gas-liquid separation zone 2 includes a fan-shaped micro-protrusion separation zone 22 corresponding to each of the spiral grooves 3 and three concentric micro-protrusion separation zones 21 located downstream. Adjacent concentric micro-protrusion separation zones 21 are separated by concave concentric deep groove rings 212.

[0006] More specifically, the fan-shaped micro-convex separation belts 22 are located in the downstream direction of the spiral groove 3 and are radially parallel to the spiral groove 3 .

[0007] More specifically, the top and bottom ends of the spiral groove 3 are parallel.

[0008] More specifically, adjacent concentric slightly convex separation bands 21 are separated by concave concentric deep groove rings 212 , and the inner diameter and outer diameter of the concentric deep groove rings 212 and the sealing end face 1 are both concentric circles.

[0009] More specifically, the micro-convex bodies 211 included in the concentric micro-convex separation belts 21 and the fan-shaped micro-convex separation belts 22 can be cylinders, cubes or regular hexagonal prisms; the height of the micro-convex bodies 211 is 0.5 to 1 micron lower than the sealing end surface.

[0010] More specifically, the radial widths of the concentric micro-convex separation bands 21 are 0.3 to 3 mm, the radial widths of the concentric deep groove rings 212 are 0.2 to 1 mm, and the pitch of the micro-convex bodies 211 is 0.02 to 0.1 mm.

[0011] The working steps of the present invention include:

[0012] 1. When the cryogenic medium leaks from the high-pressure side to the low-pressure side, the liquid of the cryogenic medium undergoes a vaporization phase change on the high-pressure side of the sealing end face 1. The vapor-liquid two-phase cryogenic medium accumulates near the downstream portion of the spiral groove 3. At this time, the spiral groove 3 acts as a storage medium.

[0013] 2. The medium continues to leak from the spiral groove 3 to the fan-shaped micro-convex separation zone 22 and the concentric micro-convex separation zone 21. The contact angle between the micro-convex body 211 and the liquid increases, preventing the liquid medium from flowing downstream; the gas phase medium leaks downstream through the gaps between the micro-convex bodies 211 and gathers in the concentric deep groove ring 212 to form a complete gas phase area. The gas-liquid interface between the area where the micro-convex body 211 is located and the concentric deep groove ring 212 forms an air curtain under the action of surface tension to prevent the medium from leaking, thereby preventing the cryogenic medium from leaking from the downstream.

[0014] The beneficial effects of the present invention are:

[0015] 1. The micro-convex separation zone on the sealing end face can increase the contact angle of the surface liquid by using the bionic hydrophobic principle of lotus leaves, and use the surface tension of the liquid to make the liquid gather in the micro-convex separation zone area, effectively preventing the seepage and leakage of the sealing medium.

[0016] 2. For low-viscosity and easily vaporized media, the gas components in the gas-liquid two-phase medium generated by the sealing end face flow into the annular deep zone through the gaps between the micro-convex bodies under the action of pressure difference, so that the liquid phase in the separation zone of the micro-convex bodies forms a Cassie droplet contact form on the upper part of the micro-convex bodies. The gas phase components in the two-phase medium form an air curtain in the annular deep zone to prevent leakage, thereby improving the sealing effect.

[0017] 3. The concentric deep groove ring, which serves as the gas phase gathering place, is lower than the end face height, which can effectively reduce the wear of the sealing end face during rotation and improve the stability of operation.

[0018] 4. The fan-shaped micro-convex separation zone is located downstream of the spiral groove and is radially aligned with the spiral groove, effectively reducing the pressure difference between the spiral groove storing cryogenic medium and the downstream, thereby curbing the resulting medium leakage. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of a mechanical seal end face structure for easily vaporized media according to the present invention.

[0020] Figure 2 It is a partial structural diagram of the sealing end face of the present invention.

[0021] Figure 3 It is a longitudinal sectional view of the sealing end face of the present invention.

[0022] Figure 4 This is a partial schematic diagram of the incomplete contact between liquid and solid caused by gas in the Cassie state. DETAILED DESCRIPTION

[0023] The following describes the specific implementation of the embodiment of the present invention in detail with reference to the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the embodiment of the present invention and is not used to limit the embodiment of the present invention.

[0024] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0025] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0026] In the present invention, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection, or communication; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0027] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0028] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0029] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with exemplary embodiments.

[0030] A mechanical seal end face structure for a medium easy to vaporize, comprising a dynamic ring and a static ring of a mechanical seal, the outer ring side of the sealing end face of the dynamic ring and the static ring is the high pressure side of the seal, namely the upstream, and the inner ring side of the sealing end face is the low pressure side of the seal, namely the downstream.

[0031] According to Figure 1 , the sealing end face 1 of at least one of the dynamic ring and the static ring is sequentially provided with a plurality of spiral grooves 3 and a gas-liquid separation zone 2 with micro convex bodies 211 from the upstream to the downstream; the gas-liquid separation zone 2 comprises a fan-shaped micro convex separation zone 22 corresponding to the spiral groove 3 and three concentric circular micro convex separation zones 21 located downstream; adjacent concentric circular micro convex separation zones 21 are separated by a concave concentric circular deep groove ring 212.

[0032] In some embodiments, the fan-shaped micro convex separation zone 22 is located in the downstream direction of the spiral groove 3, and is radially parallel to the spiral groove 3.

[0033] In some embodiments, the top end and the bottom end of the spiral groove 3 are parallel.

[0034] In some embodiments, adjacent concentric circular micro convex separation zones 21 are separated by a concave concentric circular deep groove ring 212, and the concentric circular deep groove ring 212 is concentric with the inner diameter and the outer diameter of the sealing end face 1.

[0035] In some embodiments, the micro convex bodies 211 contained in the concentric circular micro convex separation zone 21 and the fan-shaped micro convex separation zone 22 can be cylindrical, cubic or regular hexagonal; the height of the micro convex body 211 is 0.5-1 microns lower than the sealing end face.

[0036] In some embodiments, the radial width of the concentric circular micro convex separation zone 21 is 0.3-3 mm, the radial width of the concentric circular deep groove ring 212 is 0.2-1 mm, and the spacing of the micro convex body 211 is 0.02-0.1 mm.

[0037] In some embodiments, the groove edge of the fan-shaped micro convex separation zone 22 comprises a straight angle edge with an angle of 45° to the tangent of the circumference, a straight angle edge with an angle of 60° to the tangent of the circumference, and a curve inclined to the bottom of the spiral groove 3, which promotes the penetration of the medium from the bottom of the spiral groove 3 to the fan-shaped micro convex separation zone 22, and reduces the local pressure difference at the bottom of the spiral groove 3.

[0038] Through this design, when the mechanical seal is in a static state and the end face leaks, the liquid medium undergoes a vaporization phase change on the gas-liquid separation zone provided with micro convex bodies, and the generated gas is gathered in the gap between the micro convex bodies as a gas storage area, and the generated gas by the vaporization phase change changes the lubrication state on the end face to the Cassie lubrication state as shown in Figure 4, realizing the role of sealing liquid by utilizing the gas generated by vaporization. Under the action of pressure difference, the fluid flows from high pressure to low pressure, realizing multi-stage sealing of spiral groove, gas-liquid separation zone and gas curtain.

[0039] The patented micro-protrusions in this invention are based on biomimetic principles and are inspired by the natural lotus leaf. The hydrophobicity of the lotus leaf's surface is based on the micro-nano composite structure. The lotus leaf's surface is covered with a large number of irregularly arranged, dot-like protrusions, known as micropapillaries. The static contact angle of a water droplet on the lotus leaf is approximately 152.1° + 0.34°, demonstrating superhydrophobic properties.

[0040] This design eliminates the impact of high pressure at the root of the spiral groove, which is caused by the dynamic pressure effect of the spiral groove on the end face during high-speed rotation of the sealing ring. Because the pressure at the root of the groove is greater than that at other locations on the end face, this design adds a fluid pressure reduction area below the root. The hydrophobic effect of the micro-convexities on the liquid effectively eliminates the impact of high pressure at the root of the groove on leakage, and also facilitates the functioning of the gas-liquid separation zone of this design.

[0041] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A mechanical seal end face structure for easily vaporized media, comprising a dynamic ring and a static ring of the mechanical seal, wherein the outer ring side of the sealing end faces of the dynamic ring and the static ring is the sealing high-pressure side, i.e., the upstream side, and the inner ring side of the sealing end faces is the sealing low-pressure side, i.e., the downstream side, characterized in that: The sealing end surface (1) of at least one of the dynamic ring and the static ring is provided with a plurality of spiral grooves (3) and a gas-liquid separation zone (2) with micro-convex bodies (211) distributed in sequence from upstream to downstream; the gas-liquid separation zone (2) includes a fan-shaped micro-convex separation zone (22) corresponding to the spiral grooves (3) and three concentric micro-convex separation zones (21) located downstream; adjacent concentric micro-convex separation zones (21) are separated by a concave concentric deep groove ring (212).

2. The mechanical seal end face structure for easily vaporized media according to claim 1, characterized in that: The fan-shaped micro-convex separation belts (22) are located in the downstream direction of the spiral groove (3) and are radially parallel to the spiral groove (3).

3. The mechanical seal end face structure for easily vaporized media according to claim 1, characterized in that: The end of the spiral groove (3) close to the upstream of the sealing end face (1) is defined as the top end, and the end of the spiral groove (3) close to the downstream of the sealing end face (1) is defined as the bottom end; the top end and the bottom end of the spiral groove (3) are parallel.

4. The mechanical seal end face structure for easily vaporized media according to claim 1, characterized in that: The inner diameter and outer diameter of the concentric deep groove ring (212) and the sealing end face (1) are both concentric circles.

5. The mechanical seal end face structure for easily vaporized media according to claim 1, characterized in that: The micro-convex bodies (211) included in the concentric micro-convex separation belt (21) and the fan-shaped micro-convex separation belt (22) are cylindrical; the height of the micro-convex bodies (211) is 0.5 to 1 micrometer lower than the sealing end surface.

6. The mechanical seal end face structure for easily vaporized media according to claim 1, characterized in that: The micro-convex bodies (211) included in the concentric micro-convex separation belt (21) and the fan-shaped micro-convex separation belt (22) are cubes; the height of the micro-convex bodies (211) is 0.5 to 1 micrometers lower than the sealing end surface.

7. The mechanical seal end face structure for easily vaporized media according to claim 1, characterized in that: The micro-convex bodies (211) included in the concentric micro-convex separation belt (21) and the fan-shaped micro-convex separation belt (22) are regular hexagonal prisms; the height of the micro-convex bodies (211) is 0.5 to 1 micrometers lower than the sealing end surface.

8. The mechanical seal end face structure for easily vaporized media according to claim 1, characterized in that: The radial widths of the concentric micro-convex separation bands (21) are 0.3 to 3 mm, the radial widths of the concentric deep groove rings (212) are 0.2 to 1 mm, and the spacing between the micro-convex bodies (211) is 0.02 to 0.1 mm.

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