A bidirectional crescent upstream pumping type groove face mechanical seal

Abstract

The application discloses a bidirectional crescent upstream pumping type groove end face mechanical seal, which comprises a sealing ring. Different from the prior art, a plurality of upstream pumping groove groups and downstream pumping groove groups are arranged on the sealing surface of the sealing ring, the upstream pumping groove groups and the downstream pumping groove groups are alternately arranged on the sealing ring, and a sealing weir is formed between adjacent upstream pumping groove groups and downstream pumping groove groups. The upstream groove structure in the crescent shape can reduce the leakage of the fluid medium to the inner diameter side, improve the sealing performance, and timely dissipate the viscous shear heat of the sealing surface fluid, so that the temperature rise of the sealing surface is small. Meanwhile, the fluid medium can flow in a "wave shape" along the crescent-shaped flow channel in adjacent upstream grooves and downstream grooves, a stable fluid film is maintained between the sealing surfaces, the lubrication state of the sealing surface is improved, and the temperature rise and the friction torque of the sealing surface are reduced.

Description

Technical Field

[0001] This invention relates to the field of pump sealing structure technology, and in particular to a bidirectional crescent-shaped upstream pumping groove end face mechanical seal. Background Technology

[0002] Bidirectional rotatable non-contact mechanical seals have been reported, such as CN1364987A, CN1206801A, Chinese Science and Technology Journal Lubrication and Sealing, 2009, 34(12): 60-62, and foreign patents EP049937A1 and EP0632219A1. The sealing surface structure generally consists of a symmetrically arranged single or multiple rows of spiral grooves or arc grooves and a grooveless sealing dam. Some also include a radial drainage groove structure. For example, US patent US5529317, Chinese patent CN201517521, and CN101603597A adopt a combination structure of a drainage groove connected to the outer diameter side of the sealing surface and a return groove arranged circumferentially therewith. The drainage groove is used to pump the fluid medium from the upstream side into the sealing surface, while the return groove can pump the fluid medium that has leaked to the downstream side back to the upstream side, thereby reducing seal leakage. Chinese patent CN102588601A employs a fluid-type groove resembling a flower or grass shape, composed of radial drainage grooves and left and right grooves centered on the drainage grooves. Although these bidirectional rotatable non-contact mechanical seals exhibit low leakage rates and frictional power consumption within a certain speed and pressure range, the presence of the reverse groove interferes with the hydrodynamic pressure groove of the downstream pump, resulting in a significant reduction in end-face opening force and gas film stiffness. Especially under high-speed conditions, existing bidirectional rotatable non-contact mechanical seals still suffer from insufficient fluid film stiffness, high sealing leakage rates, and high end-face temperature rise. Summary of the Invention

[0003] To overcome the problems of high leakage rate and high end face temperature rise of existing gas or liquid non-contact mechanical seals during high-speed operation, this invention provides a bidirectional rotatable crescent-shaped upstream pumping groove end face sealing structure with strong end face fluid dynamic pressure effect, low sealing leakage rate and end face temperature rise under high-speed conditions.

[0004] This invention proposes a bidirectional crescent-shaped upstream pumping groove end face mechanical seal, comprising a sealing ring. Unlike existing technologies, the sealing surface of the sealing ring is provided with multiple sets of upstream and downstream pumping grooves, which are alternately distributed on the sealing ring, forming a sealing weir between adjacent upstream and downstream pumping groove sets.

[0005] When sealed, the fluid medium flows in a wave-like pattern along the upstream pumping trough, the sealing weir, and the downstream pumping trough at the end.

[0006] As a further optimization of the present invention, the sealing ring includes a stationary ring and a moving ring, and the moving ring and / or the stationary ring are provided with an upstream pumping channel group and a downstream pumping channel group.

[0007] As a further optimization of the present invention, the upstream pumping tank group includes at least two upstream tanks, and the downstream pumping tank group includes at least two downstream tanks. The upstream tank has an upstream protrusion that protrudes towards the axis of the sealing ring, and the downstream tank has a downstream protrusion that protrudes away from the axis of the sealing ring.

[0008] As a further optimization of the present invention, the upstream channel and / or the downstream channel are crescent-shaped.

[0009] As a further optimization of the present invention, at least two sets of the upstream grooves are distributed radially along the sealing ring, and a first sealing dam is formed between any two adjacent sets of the upstream grooves;

[0010] At least two sets of the downstream grooves are distributed radially along the sealing ring, and a second sealing dam is formed between any two adjacent sets of the downstream grooves.

[0011] As a further optimization of the present invention, the width of the upstream groove closer to the sealing ring axis in the same group of upstream pumping grooves is smaller than the width of the upstream groove farther from the sealing ring axis; and / or:

[0012] In the same group of downstream pumping channels, the width of the downstream channel closer to the axis of the sealing ring is smaller than the width of the downstream channel farther from the axis of the sealing ring.

[0013] As a further optimization of the present invention, the downstream groove in a set of downstream pumping grooves that is farthest from the axis of the sealing ring extends to the outside of the sealing ring;

[0014] The upstream trough furthest from the axis of the sealing ring in a set of upstream pumping troughs forms a third sealing dam with the outer side of the sealing ring;

[0015] A fourth sealing dam is formed between the upstream and downstream grooves near the axis of the sealing ring and the inner side of the sealing ring.

[0016] As a further optimization of the present invention, the depth h of the downstream trench... d The selected value range is 1 to 100 μm, and the depth h of the upstream trench is... u The selected value range is 0.5 to 50 μm.

[0017] As a further optimization of the present invention, the depth of the downstream channel is greater than the depth of the upstream channel.

[0018] As a further optimization of the present invention, the circumferential included angle θ of the slotted area of ​​a group of downstream pumping tanksdg The circumferential angle between the sealing weir adjacent to a set of downstream pumping tanks in the counterclockwise direction is θ. dl , then θ dg / θ dl =0.2~10; and / or:

[0019] The included angle θ of the circumferential angle of the slotted area of ​​a group of upstream pumping tanks ug The circumferential angle between the seals adjacent to a set of upstream pumping tanks in the counterclockwise direction is θ. ul θ ug / θ ul =0.1~10.

[0020] The bidirectional crescent-shaped upstream pumping groove end face mechanical seal proposed in this invention has the following advantages:

[0021] (1) The crescent-shaped upstream groove structure can reduce the leakage of fluid medium to the inner diameter side of the downstream groove, improve the sealing performance, and dissipate the viscous shear heat of the fluid on the sealing surface in time, maintaining a small temperature rise on the sealing surface.

[0022] (2) By rationally designing the circumferential slot width and radial position of adjacent upstream and downstream pumping tank groups, the fluid medium can flow in a “wave-like” manner along the crescent-shaped flow channel in adjacent upstream and downstream tanks, maintaining a stable fluid film between the sealing surfaces, improving the lubrication state of the sealing surfaces, and reducing the temperature rise and friction torque of the sealing surfaces.

[0023] (3) The fluid medium forms multiple radially distributed pressure peaks at the root of the downstream and upstream tanks. The superposition of each pressure peak can form a larger high-pressure zone, and the pressure distribution on the sealing surface is more uniform. This helps to improve the bearing capacity and fluid film stiffness of the sealing surface, reduce the probability of the sealing ring end face rubbing under external interference, and improve the reliability and service life of the seal.

[0024] (4) Regardless of whether the rotating shaft rotates in the forward or reverse direction, the structure of the present invention can form a continuous and stable fluid film between the sealing surfaces, and can be applied to occasions requiring bidirectional rotation.

[0025] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may become apparent by practice of the invention. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of the present invention;

[0027] Figure 2 This is a schematic diagram of the structure of the present invention;

[0028] Figure 3 This is a partial enlarged view of the present invention;

[0029] Figure 4 This is a schematic diagram of the structure of Embodiment 2 of the present invention;

[0030] Figure 5 For δ d =δ u =1.0, ε=0.5. Diagram of membrane pressure distribution at the end face of the bidirectional crescent-shaped upstream pumping trough;

[0031] Figure 6 For δ d =δ u =0.80, ε=0.5. Diagram of membrane pressure distribution at the end face of the bidirectional crescent-shaped upstream pumping trough;

[0032] Figure 7 The graph shows the variation of air film stiffness with rotational speed in the sealing performance of three types of grooved DGS.

[0033] Figure 8 The graph shows the leakage rate as a function of rotational speed for three types of grooved DGS seals.

[0034] Figure 9 The graph shows the stiffness-to-leakage ratio as a function of rotation speed for three types of grooved DGS seal performance.

[0035] Figure 10 This diagram illustrates the influence of the radial position of the upstream pumping tank on the opening force.

[0036] Figure 11 This diagram illustrates the effect of the radial position of the upstream pumping tank diameter group on the leakage rate.

[0037] Figure 12 This diagram illustrates the influence of the radial and directional positions of the upstream pumping tank diameter group on the air film stiffness.

[0038] Figure 13 This diagram illustrates the influence of the radial position of the upstream pumping tank group on the stiffness-to-leakage ratio.

[0039] In the diagram: 1. Downstream pumping tank assembly; 11. Outer downstream tank; 12. Mid-downstream tank; 13. Inner downstream tank; 2. Upstream pumping tank assembly; 21. Outer upstream tank; 22. Mid-upstream tank; 23. Inner upstream tank; 3. First sealing dam; 4. Second sealing dam; 5. Sealing weir; 6. Third sealing dam; 7. Fourth sealing dam. Detailed Implementation

[0040] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar symbols denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0041] like Figure 1-3 The illustrated bidirectional crescent-shaped upstream pumping groove end face mechanical seal includes a sealing ring. Unlike existing technologies, the sealing surface of the sealing ring is provided with multiple sets of upstream pumping groove groups 2 and downstream pumping groove groups 1. It should be noted that the sealing ring includes a stationary ring and a rotating ring, and the rotating ring and / or the stationary ring are provided with upstream pumping groove groups 2 and downstream pumping groove groups 1. The upstream pumping groove groups 2 and downstream pumping groove groups 1 are alternately distributed on the sealing ring, and adjacent upstream pumping groove groups 2 and downstream pumping groove groups 1 form a grooveless sealing weir 5.

[0042] During the sealing process, the fluid medium flows in a wave-like pattern at the end between the upstream pumping tank group 2, the sealing weir 5, and the downstream pumping tank group 1.

[0043] The upstream pumping tank group 2 includes at least two sets of upstream tanks, and the downstream pumping tank group 1 includes at least two sets of downstream tanks. Each upstream pumping tank group includes at least two sets of upstream tanks, which are radially distributed along the sealing ring, and a first sealing dam 3 is formed between any two adjacent sets of upstream tanks. The at least two sets of downstream tanks are radially distributed along the sealing ring, and a second sealing dam 4 is formed between any two adjacent sets of downstream tanks.

[0044] The upstream groove has an upstream protrusion that protrudes towards the axis of the sealing ring, and the downstream groove has a downstream protrusion that protrudes away from the axis of the sealing ring.

[0045] In this embodiment, there are three upstream and three downstream channels. The three upstream channels of a set of upstream pumping channel group 2 are defined as outer upstream channel 21, middle upstream channel 22 and inner upstream channel 23, and the three downstream channels of a set of downstream pumping channel group 1 are defined as outer downstream channel 11, middle downstream channel 12 and inner downstream channel 13. The outer downstream channel 11 and outer upstream channel 21 are located on the outside of the sealing ring, the inner downstream channel 13 and inner upstream channel 23 are located on the inside of the sealing ring, and the middle upstream channel 22 and middle downstream channel 12 are located in the middle of the sealing ring.

[0046] Preferably, the upstream and downstream channels are crescent-shaped, and the sides of both the upstream and downstream channels are arc-shaped. In some embodiments, such as... Figure 4 As shown, the sides of the upstream and downstream channels are planar.

[0047] To ensure the formation of a stable fluid film, preferably, the width of the upstream groove near the sealing ring axis in the same group of upstream pumping grooves is smaller than the width of the upstream groove far from the sealing ring axis; and the width of the downstream groove near the sealing ring axis in the same group of downstream pumping grooves is smaller than the width of the downstream groove far from the sealing ring axis.

[0048] In a set of downstream pumping channels, the downstream channel furthest from the sealing ring axis extends to the outside of the sealing ring, that is, the outer downstream channel 11 has an opening, and the opening is located on the outside of the sealing ring.

[0049] In a set of upstream pumping channels, the upstream channel furthest from the sealing ring axis forms a third sealing dam 6 with the outer side of the sealing ring;

[0050] A fourth sealing dam 7 is formed between the upstream and downstream grooves near the axis of the sealing ring and the inner side of the sealing ring.

[0051] To further ensure sealing performance, preferably, such as Figure 3 The depth h of the downstream trench shown d The selected value range is 1–100 μm, preferably 2–20 μm. In this embodiment, the depth of the downstream tank 12 is 11 μm; the depth of the upstream tank h is... u The selected value range is 0.5 to 50 μm, and the preferred value range is 1 to 10 μm. In this embodiment, the depth of the upstream groove 22 is 5.5 μm.

[0052] Preferably, the depth of the downstream tank is greater than the depth of the upstream tank.

[0053] To further ensure sealing performance, such as Figure 2 As shown: The circumferential angle corresponding to sealing weir 5 is θ. dl The circumferential angle θ of the slotted area of ​​the downstream pumping tank group 1 dg , then θ dg / θ dl =0.2~10; and

[0054] The circumferential angle θ of the slotted area of ​​the upstream pumping tank group 2 ug θ ug / θ ul =0.1~10, θ in this embodiment dg / θ dl =5.1, θ ug / θ ul =5.0.

[0055] like Figure 3As shown, the sealing ring includes an upstream and a downstream section. The upstream section of the sealing ring is the high-pressure side, and the downstream section is the low-pressure side. In this embodiment, the upstream section of the sealing ring is the outer side of the sealing ring, and the inner side of the sealing ring is the low-pressure side. The fluid medium is pumped into the outer downstream groove 11 from the upstream of the sealing ring and is pressurized at the groove root 110 of the outer downstream groove 11 to form a significant pressure peak. Part of the fluid medium flowing out of the outer downstream groove 11 enters the adjacent outer upstream groove 21 and is pressurized at the groove root 210 of the outer upstream groove 21 to form a pressure peak. The fluid medium is pumped from the downstream side to the upstream side along the crescent-shaped upstream pumping groove 21. Another part of the fluid medium enters the middle upstream groove 22 and forms a pressure peak at the groove root 220 of the middle upstream groove 22. Furthermore, a portion of the fluid medium flowing out from the outer upstream groove 21 enters the outer diameter side of the sealing surface or the adjacent outer downstream groove 11, and converges with the fluid pumped in from the outside of the sealing ring; another portion enters the middle downstream groove 12, and forms a pressure peak at the groove root 120 of the downstream pumping groove 12 along the crescent-shaped flow channel. This cycle repeats, with the fluid medium flowing in a "wavy" pattern circumferentially between the outer downstream groove 11 and outer upstream groove 21, the middle downstream groove 12 and middle upstream groove 22, and the inner downstream groove 13 and inner upstream groove 23. This maintains a uniform and stable fluid film between the sealing surfaces while reducing leakage of the fluid medium to the inner diameter side.

[0056] r i and r o These are the inner and outer diameters of the sealing end face, respectively, r. d and r u These are the root radii of the downstream outer channel 11 and the upstream outer channel 21, respectively; θ dg and θ dl The angle θ represents the circumferential angle between the downstream pumping tank group 1 (grooving area) and the adjacent sealing weir 5 in the counterclockwise direction. ug and θ ul The angle θ represents the circumferential angle between the upstream pumping tank group 2 (grooved area) and the adjacent sealing weir 5 in the counterclockwise direction. di The opening of the downstream channel 11 is located at the outer diameter r. i The circumferential angle at the location.

[0057] Define the circumferential width ratio δ of the downstream pumping tank. d The included angle θdg of the circumferential angle of the slotted area of ​​the downstream pumping tank group 1 and the included angle θ of the corresponding sealing weir 5 are... dl With θ dg The ratio of the sums, i.e., δ d =θ dg / (θ dl +θ dg Define the circumferential width ratio δ of the upstream pumping tank group. u The included angle θ of the circumferential angle of the trench area of ​​the upstream pumping tank group 2 ug The angle θ between the corresponding sealing weir and the circumferential angle 5 ul With θug The ratio of the sums, i.e., δ u =θ ug / (θ ul +θ ug ); Define the radial position coefficient ε of the upstream pumping tank group 2 as the radial width (r) between the root of the outer upstream tank 21 and the outer side of the sealing ring. o -r u The radial width (r) of the groove root of the upstream column's outer downstream groove 11 and the outer side of the sealing ring. o -r d The ratio of ε to r is ε = (r / r) o -r u ) / (r o -r d When ε=0, the root of the outer upstream groove 21 of the upstream column is connected to the outer diameter; when ε=1, the root of the outer upstream groove 21 is connected to the root of the outer downstream groove 11.

[0058] The above structure was simulated, such as... Figure 5-6 The medium pressure p shown o A schematic diagram of the film pressure distribution at the end face of the bidirectional crescent-shaped upstream pumping trough when the pressure is 1.0 MPa and the rotational speed is n = 10000 rpm. Figure 5 For δ d =δ u The end-face pressure distribution when ε = 1.0 and ε = 0.5 is as follows: Figure 6 The figure shows δ d =δ u =0.80, ε=0.5. As can be seen from the figure, significant pressure peaks are formed at the roots of the outer downstream channel 11 and outer upstream channel 21 on the upstream side, while the pressure peaks at the roots of the inner downstream channel 13 and inner upstream channel 23 on the downstream side are smaller. The superposition of these three radially distributed pressure peaks forms a large-area high-pressure zone. Structures with a small circumferential slot width ( Figure 6 Because there is a non-grooved sealing weir 5 between the upstream pumping tank group 2 and the downstream pumping tank group 1 in the circumferential direction, the high-pressure zone can be fully developed in the circumferential direction, compared to Figure 5 , Figure 6 The structure has better load-bearing capacity and air film stiffness.

[0059] like Figure 7-9 The figure shows the medium pressure p. oAt n=0.3MPa, the sealing performance parameters of the dry gas seal (DGS) of bidirectional straight groove, bidirectional T-groove, and bidirectional crescent-shaped upstream pumping groove (hereinafter referred to as "bidirectional crescent groove") vary with rotational speed. It should be noted that the radial groove width, number of cycles, and groove depth are consistent for all three groove types. As shown in the figure, under low to medium speed conditions, the bidirectional crescent groove is inferior to the bidirectional straight groove and T-groove in both film stiffness and stiffness-to-leakage ratio. With increasing rotational speed, the difference in film stiffness between the bidirectional crescent groove and the other two gradually narrows, while the stiffness-to-leakage ratio gradually surpasses them. When n=10000rpm, the film stiffness of the bidirectional crescent groove is 3%–6% lower than that of the bidirectional straight groove and T-groove, while the stiffness-to-leakage ratio is 40%–55% higher. Under all rotational speed conditions, the leakage rate of the bidirectional crescent groove is lower than that of the other two, with a reduction of 35%–50% under high-speed conditions. As can be seen from the above analysis, under high speed and low pressure conditions, due to the presence of the upstream pumping channel in the bidirectional crescent groove, the leakage rate of the bidirectional crescent groove is significantly reduced compared with the bidirectional straight groove and T-shaped groove, and the air film stiffness reduction is less than 5%, which has significantly superior comprehensive sealing performance.

[0060] like Figure 10 - Figure 13 As shown, the influence of the radial position coefficient of the upstream pumping channel group 2 on the sealing performance of the bidirectional crescent groove is observed. With the increase of the radial position coefficient of the upstream pumping channel group 2, i.e., as the upstream pumping channel group 2 gradually moves from the upstream side to the downstream side, the opening force, air film stiffness, and stiffness-to-leakage ratio all show a trend of first increasing and then decreasing, while the leakage rate monotonically increases. When ε = 1.0–1.5, the bidirectional crescent groove DGS can achieve a larger opening force, air film stiffness, and stiffness-to-leakage ratio.

[0061] It should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0062] 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 technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0063] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between the components; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0064] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature.

[0065] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A bidirectional crescent-shaped upstream pumping type groove end face mechanical seal, comprising a sealing ring, characterized in that, The sealing surface of the sealing ring is provided with multiple sets of upstream pumping groove groups (2) and downstream pumping groove groups (1). The upstream pumping groove groups (2) and the downstream pumping groove groups (1) are alternately distributed on the sealing ring, and a sealing weir (5) is formed between adjacent upstream pumping groove groups (2) and downstream pumping groove groups (1). During the sealing process, the fluid medium flows in a wave-like manner at the end between the upstream pumping tank group (2), the sealing weir (5) and the downstream pumping tank group (1); The upstream pumping tank group (2) includes at least two upstream tanks, and the downstream pumping tank group (1) includes at least two downstream tanks. The upstream tank has an upstream protrusion that protrudes towards the axis of the sealing ring, and the downstream tank has a downstream protrusion that protrudes away from the axis of the sealing ring.

2. The bidirectional crescent-shaped upstream pumping groove end face mechanical seal according to claim 1, characterized in that, The sealing ring includes a stationary ring and a moving ring, and the moving ring and / or the stationary ring are provided with an upstream pumping channel group (2) and a downstream pumping channel group (1).

3. The bidirectional crescent-shaped upstream pumping groove end face mechanical seal according to claim 1, characterized in that, The upstream channel and / or the downstream channel are crescent-shaped.

4. The bidirectional crescent-shaped upstream pumping groove end face mechanical seal according to claim 1, characterized in that, At least two sets of the upstream grooves are distributed radially along the sealing ring, and a first sealing dam (3) is formed between any two adjacent sets of the upstream grooves. At least two sets of the downstream grooves are distributed radially along the sealing ring, and a second sealing dam (4) is formed between any two adjacent sets of the downstream grooves.

5. The bidirectional crescent-shaped upstream pumping groove end face mechanical seal according to claim 4, characterized in that, In the same group of upstream grooves, the width of the upstream groove closer to the sealing ring axis is smaller than the width of the upstream groove farther from the sealing ring axis; and / or: In the same group of downstream grooves, the width of the downstream groove closer to the axis of the sealing ring is smaller than the width of the downstream groove farther from the axis of the sealing ring.

6. The bidirectional crescent-shaped upstream pumping groove end face mechanical seal according to claim 4, characterized in that, The downstream groove in a set of downstream grooves that is furthest from the axis of the sealing ring extends to the outside of the sealing ring; The upstream groove that is furthest from the axis of the sealing ring in a set of upstream grooves forms a third sealing dam (6) with the outer side of the sealing ring; A fourth sealing dam (7) is formed between the upstream and downstream grooves near the axis of the sealing ring and the inner side of the sealing ring.

7. The bidirectional crescent-shaped upstream pumping groove end face mechanical seal according to claim 4, characterized in that, The depth of the downstream tank h d The depth of the upstream trench is selected within the range of 1–100 μm. h u The selected value range is 0.5 to 50 μm.

8. The bidirectional crescent-shaped upstream pumping groove end face mechanical seal according to any one of claims 4-7, characterized in that, The depth of the downstream channel is greater than the depth of the upstream channel.

9. The bidirectional crescent-shaped upstream pumping groove end face mechanical seal according to claim 1, characterized in that, The circumferential included angle of the slotted area of ​​a set of downstream pumping tank groups (1) θ dg The circumferential angle between the sealing weir (5) adjacent to a downstream pumping tank group (1) in the counterclockwise direction is... θ dl ,but θ dg / θ dl =0.2~10; and / or: The circumferential included angle of the slotted area of ​​a set of upstream pumping tank groups (2) θ ug The circumferential angle between the sealing weir (5) adjacent to the upstream pumping tank group (2) in the counterclockwise direction is... θ ul , θ ug / θ ul =0.1~10.

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