Sealing mechanism and vacuum pump

Abstract

The embodiment of the utility model provides a sealing mechanism and a vacuum pump. The sealing mechanism comprises a movable sealing ring, a static sealing ring, a shaft sleeve and a flexible sealing piece. Wherein the movable sealing ring is used for sleeving a rotating shaft, the static sealing ring is used for being fixed to the static ring seat, and the shaft sleeve is used for sleeving the rotating shaft and located on the side, away from the movable sealing ring, of the static sealing ring. On the basis, the static sealing ring and the movable sealing ring jointly form a labyrinth sealing structure, the shaft sleeve is provided with a mounting groove communicated with the labyrinth sealing structure, and the flexible sealing piece is located in the mounting groove. On the basis, the static sealing ring, the movable sealing ring, the shaft sleeve and the flexible sealing piece have a synergistic effect, so that a fluid medium flows to the mounting groove through the sealing labyrinth structure, the flexible sealing piece in the mounting groove is selectively attached to the static sealing ring in a sealing mode under the action of the fluid medium, and then lubricating oil is prevented from flowing from an oil tank lubricating cavity to a vacuum cavity.

Description

TECHNICAL FIELD

[0001] The utility model relates to a sealing technical field, specifically, relate to a sealing mechanism and vacuum pump. BACKGROUND

[0002] In the working process, there is relative motion between the rotating parts and the stationary parts inside the vacuum pump, so appropriate sealing measures need to be adopted to ensure the effective isolation of the oil tank lubrication cavity and the vacuum cavity. Specifically, the process gas in the vacuum cavity must be prevented from leaking into the oil tank lubrication chamber to avoid affecting the quality and lubrication effect of the lubricating oil; at the same time, the oil gas mixture in the oil tank lubrication chamber must also be prevented from entering the vacuum cavity to prevent pollution to the ongoing process.

[0003] Because the pressure in the vacuum cavity is usually lower than the pressure in the oil tank lubrication chamber, the common sealing method on the market is to use a labyrinth seal combined with a dynamic seal (such as a piston ring or a lip seal ring). Simply put, it is to form a complex channel by interlacing multiple annular structures, so that it is difficult for lubricating oil to pass through these channels and enter the vacuum cavity. However, the inventors have found that the above method can seal to some extent, but over a long period of operation, leakage problems still occur. In particular, under conditions where the pressure difference between the oil tank side and the vacuum side is large, lubricating oil is more likely to break through the sealing layer. SUMMARY

[0004] To solve the above problems, the purpose of the utility model is to provide a sealing mechanism and a vacuum pump, which can effectively reduce the risk of leakage caused by pressure fluctuations and further improve the sealing performance, so as to always ensure that the vacuum pump is in the best sealed state.

[0005] The sealing mechanism provided by the utility model embodiment comprises a dynamic sealing ring, a static sealing ring, a shaft sleeve and a flexible sealing piece, wherein the dynamic sealing ring is used for sleeving on a rotating shaft, the static sealing ring is used for fixing on a static ring seat, and the dynamic sealing ring and the static sealing ring jointly form a sealing labyrinth structure; the shaft sleeve is used for sleeving on the rotating shaft and is located on the side of the static sealing ring away from the dynamic sealing ring, and is provided with a mounting groove in communication with the sealing labyrinth structure; the flexible sealing piece is located in the mounting groove and is used for selectively sealingly abutting against the static sealing ring under the action of a fluid medium.

[0006] Therefore, through the cooperative action of the static sealing ring, the dynamic sealing ring, the shaft sleeve and the flexible sealing piece, the fluid medium flows to the mounting groove through the sealing labyrinth structure, so that the flexible sealing piece in the mounting groove selectively seals and abuts against the static sealing ring under the action of the fluid medium, thereby hindering the flow of lubricating oil from the oil tank lubrication cavity to the vacuum cavity. BRIEF DESCRIPTION OF DRAWINGS

[0007] In order to more clearly illustrate the technical scheme of the embodiments of the present application, the drawings used in the embodiments will be briefly introduced as follows. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope, and for those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0008] Figure 1 The structural schematic view of the sealing mechanism provided for the present embodiment is shown in the figure.

[0009] Figure 2 The structural schematic view of the sealing mechanism provided for the present embodiment is shown in the figure. Figure 1 The sectional view of A-A in the figure.

[0010] Figure 3 The structural schematic view of the sealing mechanism provided for the present embodiment is shown in the figure. Figure 2 The enlarged schematic view of A in the figure. Figure 1 ;

[0011] Figure 4 The structural schematic view of the sealing mechanism provided for the present embodiment is shown in the figure. Figure 2 The enlarged schematic view of A in the figure. Figure 2 ;

[0012] Figure 5 The structural schematic view of the static sealing ring provided for the present embodiment is shown in the figure.

[0013] Figure 6 The structural schematic view of the static sealing ring provided for the present embodiment is shown in the figure.

[0014] Figure 7 The structural schematic view of the sealing mechanism provided for the present embodiment is shown in the figure. Figure 6 The sectional view of B-B in the figure.

[0015] Figure 8 The structural schematic view of the sealing mechanism provided for the present embodiment is shown in the figure.

[0016] Figure 9 The structural schematic view of the sealing mechanism provided for the present embodiment is shown in the figure. Figure 8 The sectional view of C-C in the figure.

[0017] Figure 10 The enlarged schematic view of C in the figure. Figure 9 The enlarged schematic view of C in the figure.

[0018] Figure 11 The structural schematic view of the flexible sealing member provided for the present embodiment is shown in the figure.

[0019] Icon: 10-sealing mechanism; 30-rotary shaft; 50-static ring seat; 100-moving sealing ring; 110-first cavity; 130-second cavity; 150-third cavity; 170-spiral structure; 300-static sealing ring; 310-sealing part; 500-shaft sleeve; 510-mounting groove; 511-guiding fillet; 700-flexible sealing piece; 710-arc-shaped sealing section; 711-guiding slope; 910-first gap; 930-second gap; 950-third gap. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings can be arranged and designed in various different configurations.

[0021] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of the present application.

[0022] It should be noted that: similar reference numbers and letters represent similar items in the following drawings, therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0023] In the description of the present application, it should be noted that if the terms "upper", "lower", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship when the product of the present application is usually placed, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, therefore, it cannot be understood as a limitation on the present application.

[0024] In addition, if the terms "first", "second" and the like appear, they are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0025] It should be noted that the features in the embodiments of the present application can be combined with each other without conflict.

[0026] The overall structure, working principle and technical effects of the sealing mechanism 10 are described in detail below through embodiments and in combination with the drawings. Please refer to Figures 1 to 3 The utility model provides a kind of sealing mechanism 10, including dynamic sealing ring 100, static sealing ring 300, shaft sleeve 500 and flexible sealing piece 700, it is applied to vacuum pump, to improve the sealing efficiency of vacuum pump.

[0027] The vacuum pump includes the sealing mechanism 10, the static ring seat 50 and the rotating shaft 30 described above. Among them, the shaft sleeve 500 and the dynamic sealing ring 100 are sleeved on the rotating shaft 30, the static sealing ring 300 is fixed on the static ring seat 50, and is located between the shaft sleeve 500 and the dynamic sealing ring 100. Optionally, the static ring seat 50 can be the bearing plate of the vacuum pump. The vacuum pump has a simple structure, low cost, can effectively reduce the risk of leakage caused by pressure fluctuation, further improve the sealing performance, so as to ensure that it is always in the best sealing state.

[0028] In the sealing mechanism 10, as mentioned above, the dynamic sealing ring 100 is used to be sleeved on the rotating shaft 30, the static sealing ring 300 is used to be fixed on the static ring seat 50, and the shaft sleeve 500 is used to be sleeved on the rotating shaft 30, located on the side of the static sealing ring 300 away from the dynamic sealing ring 100. It needs to be pointed out that the dynamic sealing ring 100 here is adjacent to the side of the oil tank lubricating cavity, and the shaft sleeve 500 here is adjacent to the side of the vacuum cavity.

[0029] On the basis described above, as shown in Figure 3 The static sealing ring 300 and the dynamic sealing ring 100 jointly constitute a labyrinth sealing structure, the shaft sleeve 500 is provided with a mounting groove 510 in communication with the sealing labyrinth structure, and the flexible sealing piece 700 is located in the mounting groove 510. Based on this, the static sealing ring 300, the dynamic sealing ring 100, the shaft sleeve 500 and the flexible sealing piece 700 cooperate to make the fluid medium flow to the mounting groove 510 through the sealing labyrinth structure, so that the flexible sealing piece 700 in the mounting groove 510 is selectively sealed and fitted with the static sealing ring 300 under the action of the fluid medium, thereby hindering the flow of lubricating oil from the oil tank lubricating cavity to the vacuum cavity.

[0030] In practical application, the flexible sealing piece 700 can float with the change of pressure difference. Specifically, under the condition that the pressure on the oil tank side is larger, the flexible sealing piece 700 will be blown up by the fluid medium and tightly fitted to the static sealing ring 300, forming a tighter contact surface; under the condition that the pressure areas on the oil tank side and the vacuum cavity side are balanced, the flexible sealing piece 700 can automatically reset without affecting normal operation. Based on this, the sealing mechanism 10 provided by the present application effectively reduces the risk of leakage caused by pressure fluctuation, and further improves the sealing performance.

[0031] In addition, it should be noted that the flexible floating member is made of high wear-resistant polymer material. Optionally, the flexible floating member can be made of PPS (polyphenylene sulfide), PTFE (polytetrafluoroethylene) or PEEK (polyether ether ketone).

[0032] Please refer again to Figure 3 and Figure 4 In optional embodiments, the sealing labyrinth structure includes a first cavity 110 formed by the radially recessed outer circumferential surface of the dynamic sealing ring 100, and an annular chamber formed by the axially recessed outer end surface of the dynamic sealing ring 100. On this basis, to further increase the complexity of the sealing labyrinth structure and enhance the flow resistance of the lubricating oil through the sealing labyrinth structure, the inner end surface of the static sealing ring 300 is formed with a sealing portion 310 by being axially protruded. Moreover, the sealing portion 310 is L-shaped, and can divide the annular chamber into a second cavity 130 and a third cavity 150 that are in communication with each other.

[0033] It is easy to understand that the first cavity 110 is in communication with the oil tank lubricating cavity, the second cavity 130 is in communication with the first cavity 110, and the third cavity 150 is in communication with the mounting groove 510. Based on the above, in the process of migrating from the oil tank lubricating cavity to the vacuum cavity, the fluid medium needs to pass through the sealing labyrinth structure formed by the tortuous path of the cavities, and at the same time needs to overcome the structural restriction by turning multiple times. Therefore, it is also explained that the sealing labyrinth structure provided by the application effectively enhances the sealing performance by using a tortuous path, thereby effectively preventing the fluid medium from migrating from the oil tank lubricating cavity to the vacuum cavity.

[0034] Further, the sealing labyrinth structure further includes a first gap 910 connecting the first cavity 110 and the second cavity 130, a second gap 930 connecting the second cavity 130 and the third cavity 150, and a third gap 950 connecting the third cavity 150 and the mounting groove 510. To further control the flow of the fluid medium and thus realize mechanical sealing, the maximum cross-sectional area d in the first gap 910, the second gap 930 and the third gap 950 satisfies the following relationship with the minimum cross-sectional area D of the first cavity 110, the second cavity 130 and the third cavity 150: D>d. Optionally, the ratio of d / D ranges from 50% to 80%.

[0035] In practical applications, since the pressure of the oil tank lubricating cavity is greater than that of the vacuum cavity, and the cross-sectional area of any gap is smaller than that of the cavity, in the process of flowing from the oil tank lubricating cavity to the vacuum cavity, the speed of the fluid medium increases when passing through any narrow gap, and then, when entering the larger cavity from the gap, the flow rate of the fluid medium will decrease due to the sudden expansion of the area at this time, thereby forming strong vortex and turbulence, so that the lubricating oil in the fluid medium cannot pass through, realizing sealing.

[0036] Please refer to Figures 5 to 7 , the annular chamber is provided with a spiral structure 170 near the side of the shaft center of the dynamic sealing ring 100, and the spiral line of the spiral structure 170 is inclined to the side of the shaft center of the dynamic sealing ring 100, which is a tapered spiral line. It is easy to understand that when the lubricating oil in the fluid medium flows along the spiral line, on the one hand, it can be guided by the spiral line and flow back to the oil tank lubricating cavity; on the other hand, it can also carry away the heat generated by friction and dissipate heat for the sealing mechanism 10. In addition, it should be noted that the above-mentioned spiral structure 170 can also improve the tortuosity of the sealing labyrinth structure, provide sealing efficiency, and at the same time prevent dust, impurities and other pollutants from entering the lubricating area, effectively block external pollutants, and maintain the beneficial effect of cleanliness.

[0037] In addition, it should be further pointed out that the parametric equation of the tapered spiral line provided in the present application is:

[0038] X = (R0+Kt)cos(t);

[0039] Y = (R0+Kt)sin(t);

[0040] Z = ct.

[0041] Wherein, R0 is the radius of the spiral line at t = 0, K is the increase rate of the radius with the angle variable t (spiral line curvature), and c is the moving distance in the Z axis direction per revolution (spiral line pitch). In the present application, the size of R0 is equal to the opening radius of the dynamic sealing ring 100; the pitch c ≥ 1.25 mm; the spiral line curvature k ≥ 5°; the number of spiral lines ≥ 3. The sealing mechanism 10 of the dynamic sealing ring 100 provided with the above-mentioned spiral structure 170 is specifically shown in Figures 8 to 9 .

[0042] In addition, as shown in Figure 10 , the number of mounting grooves 510 can be multiple. In some embodiments, the mounting groove 510 is an annular groove coaxially arranged with the rotating shaft 30. Accordingly, the flexible sealing piece 700 can be arranged as an annular sealing piece corresponding to the mounting groove 510. Alternatively, as shown in Figure 11 , the flexible sealing piece 700 can include at least two arc-shaped sealing segments 710, and the at least two arc-shaped sealing segments 710 are arranged in any one annular groove. It is easy to understand that by splitting the flexible sealing piece 700 in one mounting groove 510 into at least two ends, the pressure difference between the oil tank side and the vacuum cavity side can be avoided, and the flexible sealing piece 700 can be difficult to blow up.

[0043] Please refer to Figure 3 and Figure 4, the extending depth h of the mounting groove 510 along the axial direction and the extending height H of the flexible seal 700 along the axial direction satisfy the following relationship: 0.1mm≤H-h≤0.3mm. That is, the extending height H of the flexible seal 700 along the axial direction is greater than the extending depth h of the mounting groove 510 along the axial direction, and the flexible seal 700 is partially located outside the mounting groove 510, so that there is a gap (the aforementioned third gap 950) between the sleeve 500 and the static seal ring 300, and the fluid medium can blow the flexible seal 700 through the gap, so that the flexible seal 700 floats with the change of pressure, which will not be described here.

[0044] Further, the extending width a of the mounting groove 510 along the radial direction and the extending width A of the flexible seal 700 along the radial direction satisfy the following relationship: A / 5≤a-A. That is, there is a gap between the groove wall of the mounting groove 510 in the radial direction and the flexible seal 700. Similarly as described above, the fluid medium can blow the flexible seal 700 through the gap, so that the flexible seal 700 floats with the change of pressure. Optionally, the cross-sectional area of the flexible seal 700 is 1mm 2 to 25mm 2 .

[0045] It is considered that the inclined structure has a certain guiding effect, and the side of the groove wall of the mounting groove 510 close to the axis of the sleeve 500 is provided with a guide round corner 511, and the radius R of the guide round corner 511 satisfies the following relationship: 1mm≤R. It is easy to understand that the guide round corner 511 can make the airflow blow smoothly through the bottom of the flexible seal 700, and then make it axially close to the static seal ring 300. Correspondingly, the side of the flexible seal 700 close to the axis of the sleeve 500 is provided with a guide inclined surface 711, the guide inclined surface 711 is inclined towards the direction away from the axis of the sleeve 500, and the inclination angle θ of the guide inclined surface 711 is in the range of 15°-25°. Based on this, the fluid medium will increase the blowing force when passing through the guide inclined surface 711 at the bottom of the flexible seal 700, so that it is easier to blow up the flexible seal 700.

[0046] Taking the sealing mechanism 10 provided in the present application as an example, the specific working process and working principle are as follows:

[0047] When the pressure of the oil tank lubrication cavity is greater than the pressure of the vacuum cavity, the fluid medium flows from the oil tank lubrication cavity to the first cavity 110, then to the second cavity 130 through the first gap 910, then to the third cavity 150 through the second gap 930, and then to the mounting groove 510 through the third gap 950. In the above process, since the fluid medium constantly enters the wide cavity from the narrow gap and then enters the narrow gap from the wide cavity, strong vortex and turbulence are generated, so that the lubricating oil in the fluid medium cannot pass through and is guided back to the oil tank lubrication cavity through the spiral structure 170 of the second cavity 130 and the third cavity 150. Subsequently, the fluid medium entering the mounting groove 510 blows against the side of the flexible sealing piece 700 and the mounting groove 510 through the guide slope 711, thereby blowing up the flexible sealing piece 700 so that the flexible sealing piece 700 tightly abuts against the static sealing ring 300 to form a tight contact surface and achieve sealing. When the pressure areas of the oil tank side and the vacuum cavity side are balanced, the flexible sealing piece 700 can automatically reset without affecting normal operation.

[0048] In summary, the sealing mechanism 10 and the vacuum pump are provided. The sealing mechanism 10 includes the dynamic sealing ring 100, the static sealing ring 300, the shaft sleeve 500, and the flexible sealing piece 700. The dynamic sealing ring 100 is arranged on the rotating shaft 30, the static sealing ring 300 is fixed on the static ring seat 50, and the shaft sleeve 500 is arranged on the rotating shaft 30 and located on the side of the static sealing ring 300 away from the dynamic sealing ring 100. On the basis of the above, the static sealing ring 300 and the dynamic sealing ring 100 jointly form a labyrinth sealing structure, the shaft sleeve 500 is provided with the mounting groove 510 in communication with the sealing labyrinth structure, and the flexible sealing piece 700 is located in the mounting groove 510. Based on this, the static sealing ring 300, the dynamic sealing ring 100, the shaft sleeve 500, and the flexible sealing piece 700 cooperate to make the fluid medium flow to the mounting groove 510 through the sealing labyrinth structure, so that the flexible sealing piece 700 in the mounting groove 510 selectively abuts against the static sealing ring 300 under the action of the fluid medium, thereby hindering the lubricating oil from flowing from the oil tank lubrication cavity to the vacuum cavity.

[0049] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto. Any changes or replacements within the technical range disclosed by the present application can be easily thought of by those skilled in the art, and should be covered within the protection scope of the present application.

Claims

1. A sealing mechanism, characterized in that, include: A dynamic sealing ring (100) is used to be sleeved on the rotating shaft (30); A static sealing ring (300) is used to fix the static ring seat (50) and together with the dynamic sealing ring (100) forms a sealing labyrinth structure. A bushing (500) is used to be sleeved on the rotating shaft (30), located on the side of the static sealing ring (300) away from the dynamic sealing ring (100), and is provided with an installation groove (510) communicating with the sealing labyrinth structure. A flexible seal (700) is located within the mounting groove (510) and is used to selectively seal against the static sealing ring (300) under the action of a fluid medium.

2. The sealing mechanism according to claim 1, characterized in that, The axial extension depth h of the mounting groove (510) and the axial extension height H of the flexible seal (700) satisfy the following relationship: 0.1mm≤Hh≤0.3mm.

3. The sealing mechanism according to claim 1, characterized in that, The radial extension width a of the mounting groove (510) and the radial extension width A of the flexible seal (700) satisfy the following relationship: A / 5 ≤ aA.

4. The sealing mechanism according to claim 1, characterized in that, The mounting groove (510) has a guide fillet (511) on the side of the groove wall near the axis of the bushing (500), and the radius R of the guide fillet (511) satisfies the following relationship: 1mm≤R.

5. The sealing mechanism according to claim 1, characterized in that, The flexible seal (700) has a guide slope (711) on the side near the axis of the bushing (500). The guide slope (711) is inclined in a direction away from the axis of the bushing (500), and the inclination angle θ of the guide slope (711) is in the range of 15° to 25°.

6. The sealing mechanism according to claim 1, characterized in that, The mounting groove (510) is an annular groove coaxially arranged with the rotating shaft (30), and the flexible seal (700) includes at least two arc-shaped sealing sections (710), and the at least two arc-shaped sealing sections (710) are spaced apart in any one of the annular grooves.

7. The sealing mechanism according to any one of claims 1 to 6, characterized in that, The sealed labyrinth structure includes: a first cavity (110) formed by radially recessing the outer peripheral surface of the dynamic sealing ring (100), and an annular chamber formed by axially recessing the outer end surface of the dynamic sealing ring (100). The inner end face of the static sealing ring (300) protrudes axially to form a sealing part (310). The sealing part (310) is L-shaped and can divide the annular chamber into a second cavity (130) and a third cavity (150) that are interconnected. The second cavity (130) is connected to the first cavity (110), and the third cavity (150) is connected to the mounting groove (510).

8. The sealing mechanism according to claim 7, characterized in that, The sealed labyrinth structure further includes: a first gap (910) connecting the first cavity (110) and the second cavity (130), a second gap (930) connecting the second cavity (130) and the third cavity (150), and a third gap (950) connecting the third cavity (150) and the mounting groove (510); The maximum cross-sectional area d in the first gap (910), the second gap (930) and the third gap (950) satisfies the following relationship with the minimum cross-sectional area D of the first cavity (110), the second cavity (130) and the third cavity (150): D > d.

9. The sealing mechanism according to claim 7, characterized in that, The annular chamber has a spiral structure (170) on the side near the axis of the dynamic sealing ring (100), and the spiral line of the spiral structure (170) is inclined to the side of the axis of the dynamic sealing ring (100).

10. A vacuum pump, characterized in that, It includes a stationary ring seat (50), a rotating shaft (30), and a sealing mechanism (10) as described in any one of claims 1 to 9; wherein the bushing (500) and the dynamic sealing ring (100) are sleeved on the rotating shaft (30), and the stationary sealing ring (300) is fixed on the stationary ring seat (50) and located between the bushing (500) and the dynamic sealing ring (100).

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