Mechanical sealing end face structure for easy-to-vaporize medium

Abstract

A mechanical seal end face structure for an easily vaporized medium comprises a moving ring and a static ring of a mechanical seal, the outer ring side of the sealing end face of the moving ring and the static ring is the sealing high-pressure side, namely the upstream, and the inner ring edge side of the sealing end face is the sealing low-pressure side, namely the downstream. A plurality of spiral grooves and gas-liquid separation belts with micro-protrusions are sequentially distributed on the sealing end face of at least one of the movable ring and the static ring from upstream to downstream. The gas-liquid separation zone comprises a fan-shaped micro-convex separation zone and a concentric circle micro-convex separation zone; a concentric circle deep groove ring is arranged between every two adjacent concentric circle micro-convex separation belts; the effect of sealing liquid through gas generated by vaporization is achieved, multi-stage sealing of the spiral groove, the gas-liquid separation belt and the gas curtain is achieved, and the abrasion speed 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 vaporizable media. Background Art

[0002] In the aerospace field, cryogenic propellants, mainly liquid hydrogen, liquid oxygen, and liquid methane, are the main media for heavy-lift launch vehicles. In the aerospace field, power units use shaft seals to prevent the leakage of the above-mentioned cryogenic and easily vaporized dangerous media. The shaft seal seals the fluid by combining the end faces of a rotating dynamic ring and a stationary static ring. Compared with traditional media, the cryogenic media used in the aerospace field have low viscosity and are easy to vaporize. Therefore, cryogenic media are very likely to leak through the sealing end face under high pressure difference conditions, posing severe challenges to the safe and reliable operation of key power equipment. Taking aerospace engines as an example, after filling with cryogenic fuel and oxidizer, the turbopump is in a shutdown state. Under the pressure difference of the sealing medium, the low-temperature and low-viscosity medium is very likely to leak through the sealing end face, and phase change occurs during the leakage process due to the pressure reduction. In severe cases, the sealing end face will open and cause a large amount of leakage, affecting the safety of the aerospace engine.

[0003] The invention with publication number CN103470773B discloses a bird-wing-like multi-channel groove end face sealing structure, which reduces the local pressure on the sealing end face caused by the penetration of the medium by adding a bird-wing-like drainage groove with diversion and pressure stabilization functions on the sealing end face of the dynamic ring of the shaft seal. However, this design is severely worn when running at high speed, which is not conducive to the stable operation of the equipment; and it lacks the ability to separate gas and liquid, which easily causes the medium to accumulate locally to generate high pressure and then leak. Summary of the invention

[0004] In view of the above problems, the present invention proposes a mechanical seal end face structure for easily vaporized media. Its design concept is to combine the micro-convex ring belt for collecting liquid and the concave concentric circle deep groove ring that easily forms an air curtain, thereby improving the air tightness and reducing the wear of the mechanical seal end face, and efficiently realizing the gas-liquid separation of the medium, thereby inhibiting and reducing the leakage of low-viscosity easily vaporized media at the mechanical seal end face.

[0005] A mechanical seal end face structure for easily vaporized media includes a dynamic ring and a static ring of a 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, and the inner ring side of the sealing end faces is the sealing low-pressure side, i.e., the downstream. 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 upstream to downstream; the gas-liquid separation zone 2 includes a fan-shaped micro-convex separation zone 22 corresponding to the spiral grooves 3 one by one and three concentric micro-convex separation zones 21 located downstream; and adjacent concentric micro-convex separation zones 21 are separated by a concave concentric deep groove ring 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 micro-convex separation zones 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 may 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 belts 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.

[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, and the vapor-liquid two-phase cryogenic medium gathers at the downstream portion of the spiral groove 3. At this time, the spiral groove 3 plays the role of storing the 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, and the contact angle between the micro-convex body 211 and the liquid increases, preventing the liquid phase 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 medium leakage, 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 surface 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 the 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, and 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 radially aligned with the spiral groove, which effectively reduces the pressure difference between the spiral groove storing cryogenic medium and the downstream, and curbs 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 cross-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 specific implementation of the embodiment of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here 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 is to 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”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element 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] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0026] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0027] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0028] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means 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 may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

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

[0030] A mechanical seal end face structure for easily vaporized media includes 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, and the inner ring side of the sealing end faces is the sealing low-pressure side, i.e., 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 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 concave concentric deep groove rings 212.

[0032] In some embodiments, 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 .

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

[0034] In some embodiments, adjacent concentric micro-convex separation zones 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 surface 1 are both concentric circles.

[0035] In some embodiments, the micro-convex bodies 211 included in the concentric micro-convex separation belts 21 and the fan-shaped micro-convex separation belts 22 may 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.

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

[0037] In some embodiments, the groove edge of the fan-shaped micro-convex separation belt 22 includes a right-angled side at a 45° angle to the circumferential tangent, a right-angled side at a 60° angle to the circumferential tangent, and a curve inclined toward the bottom of the spiral groove 3, thereby promoting the medium to penetrate from the bottom of the spiral groove 3 to the fan-shaped micro-convex separation belt 22 and reducing the local pressure difference at the bottom of the spiral groove 3.

[0038] Through this design, when the mechanical seal is in a stationary state and the end face leaks, the liquid medium undergoes a vaporization phase change on the gas-liquid separation zone with micro-convex bodies, and the generated gas passes through the gaps between the micro-convex bodies and gathers in the gas storage area. The gas generated by the vaporization phase change is used to change the lubrication state on the end face to the Cassie lubrication state. Figure 4, realizing the function 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 belt and gas curtain.

[0039] The micro-convex body of the present invention is based on the idea of ​​bionics, relying on the natural lotus leaf, and based on the hydrophobic action mechanism of the micro-nano composite structure on the surface of the lotus leaf. There are a large number of irregularly arranged dot-shaped protrusions on the surface of the lotus leaf, which are called micro-papillary structures. The static contact angle of a water droplet on the surface of the lotus leaf is about 152.1+0.34°, which has super hydrophobic properties.

[0040] This design solves the problem of the high pressure at the root of the spiral groove on the leakage caused by the dynamic pressure effect of the spiral groove on the end face when the sealing ring rotates at high speed. Since the pressure at the root of the groove is greater than the pressure at other positions on the end face, this design adds a fluid decompression area below the root of the groove. The hydrophobic effect of the micro-convex body on the liquid can effectively eliminate the influence of the high pressure at the root of the groove on the leakage, and at the same time, it is more conducive to the function of the gas-liquid separation zone of this design.

[0041] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary 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 a 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, and the inner ring side of the sealing end faces is the sealing low pressure side, i.e., the downstream, and is 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) comprises a fan-shaped micro-convex separation zone (22) corresponding to the spiral grooves (3) one by one and three concentric micro-convex separation zones (21) located downstream; and adjacent concentric micro-convex separation zones (21) are separated by concave concentric deep groove rings (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 surface (1) is defined as the top end, and the end of the spiral groove (3) close to the downstream of the sealing end surface (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: Adjacent concentric micro-convex separation zones (21) are separated by concave concentric deep groove rings (212), and the inner diameter and outer diameter of the concentric deep groove ring (212) and the sealing end surface (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 micron 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 cubic; the height of the micro-convex bodies (211) is 0.5 to 1 micron 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 micron 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 belts (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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