Shaft seal structure of medical anti-corrosion screw vacuum pump

Abstract

The invention provides a shaft seal structure of a medical anti-corrosion screw vacuum pump, and belongs to the technical field of screw vacuum pumps. The mechanical sealing structure solves the technical problem that the continuous and stable sealing effect of an existing mechanical sealing structure of the screw vacuum pump is difficult to guarantee. The medical anti-corrosion screw vacuum pump comprises a machine shell, a side cover and a rotating shaft, a lubricating oil way and a lubricating oil cavity are formed in the side cover, a shaft seal structure comprises a movable ring and a static ring, the side cover comprises a retainer, the end face, facing the static ring, of the movable ring is provided with a lubricating groove arranged in the circumferential direction, the cross section of the lubricating groove is in a fishbone shape connected end to end, and an oil through hole is formed in the end face of the static ring. The oil outlet end of the oil through hole is communicated with the lubricating groove, the oil inlet end of the oil through hole is communicated with the lubricating oil way, an oil outlet cavity communicated with the lubricating groove is formed between the inner edge of the static ring and the rotating shaft, an annular oil outlet channel is formed between the inner hole of the retainer and the rotating shaft, and the two ends of the oil outlet channel are communicated with the oil outlet cavity and the lubricating oil cavity respectively. The screw vacuum pump can guarantee better corrosion resistance.

Description

Technical Field

[0001] The present invention belongs to the technical field of screw vacuum pumps, and relates to a shaft seal structure of a medical anti-corrosion screw vacuum pump. Background Art

[0002] A screw vacuum pump is a gas extraction device that uses a pair of screws to rotate synchronously and at high speed in the pump housing to generate suction and exhaust effects. It is an upgraded product of oil-sealed vacuum pumps and can pump gases containing a large amount of water vapor and a small amount of dust. It is widely used in domestic enterprises in the pharmaceutical, chemical, semiconductor and other fields with high requirements for clean vacuum. In terms of the sealing form of the screw rotating shaft, mechanical seals are often used. A mechanical seal device consists of at least a pair of dynamic and static rings perpendicular to the axis, and the dynamic or static ring acts as a compensation ring under the action of an axial elastic element (spring) to keep the dynamic and static rings in a fitting, sliding and rotating fit, preventing the working fluid from leaking along the rotating shaft.

[0003] The patent with the application number: CN200920013059.9 discloses a labyrinth composite mechanical seal device, including at least a pair of dynamic and static rings perpendicular to the axis, and the dynamic or static ring acts as a compensation ring under the action of an axial elastic element to keep the dynamic and static rings in a fitting, sliding and rotating fit. The dynamic ring is connected to the shaft or shaft sleeve, and the static ring is connected to the gland on the body. A labyrinth seal sleeve is provided between the shaft hole of the body and the shaft. The labyrinth seal sleeve is fixedly installed on the shaft. Thread grooves are provided on the front half of the outer ring surface of the labyrinth seal sleeve. The outer ring surface of the labyrinth seal sleeve is in a sliding and rotating fit with the shaft hole of the body. The thread grooves on the labyrinth seal sleeve and the shaft hole of the body form a screw pump to transport the medium particles entering the thread grooves of the labyrinth seal sleeve back to the front end of the labyrinth seal sleeve, so that the particles in the medium cannot pass through.

[0004] The above device can achieve the shaft seal of the screw vacuum pump, but there are still some deficiencies: such as when the exhaust pressure fluctuates, the lubricating medium film on the sealing surface is unstable, generating high temperature, accelerating wear and failure, etc. The direct contact between the end faces of the dynamic and static rings results in a large frictional resistance. High-speed friction will generate a large amount of heat and accelerate wear, leading to seal failure and allowing corrosive media to invade. Therefore, those of ordinary skill in the art usually easily consider: 1. Continuously spray lubricating oil above the dynamic and static rings so that the lubricating oil continuously drips onto the joint surface of the dynamic and static rings to provide continuous lubrication and cooling; 2. Polish the contact surfaces of the dynamic and static rings to make them fit tightly and reduce the friction coefficient between them, increasing the sealing effect. Summary of the Invention

[0005] In view of the above problems existing in the prior art, the present invention provides a shaft seal structure of a medical anti-corrosion screw vacuum pump. The technical problem to be solved by the present invention is that the existing mechanical seal structure is difficult to ensure a continuous and stable sealing effect.

[0006] The object of the present invention can be achieved by the following technical solutions:

[0007] A shaft seal structure of a medical anti-corrosion screw vacuum pump. The vacuum pump includes a casing, a side cover and a rotating shaft. The side cover has a lubricating oil passage and a lubricating oil chamber for supplying oil to the lubricating oil passage. The shaft seal structure includes a moving ring and a stationary ring arranged coaxially. The moving ring is fixedly sleeved on the outer periphery of the rotating shaft. The side cover includes an annular retaining frame. The stationary ring is coaxially and slidably embedded at one end of the retaining frame and always has a tendency to move towards the moving ring. It is characterized in that the end face of the moving ring facing the stationary ring has a lubricating groove arranged circumferentially. The cross-section of the lubricating groove is in the shape of a fishbone connected end to end. The maximum dimension of the outer edge of the lubricating groove along the radial direction is smaller than the outer diameter dimension of the end face of the stationary ring and larger than the inner diameter dimension of the end face of the stationary ring. The minimum dimension of the outer edge of the lubricating groove along the radial direction is smaller than the inner diameter dimension of the end face of the stationary ring. The end face of the stationary ring has an oil passage hole. The oil outlet end of the oil passage hole is communicated with the lubricating groove. The oil inlet end of the oil passage hole is communicated with the lubricating oil passage. An oil outlet chamber communicated with the lubricating groove is formed between the inner edge of the stationary ring and the rotating shaft. An annular oil outlet passage is formed between the inner hole of the retaining frame and the rotating shaft. The two ends of the oil outlet passage are respectively communicated with the oil outlet chamber and the lubricating oil chamber.

[0008] The lubricating oil passage can be an existing structure inside the side cover for supplying lubricating oil to the rotating shaft bearing. The lubricating oil chamber is used for storing lubricating oil. The lubricating oil in the lubricating oil chamber can be pressurized and sent to the lubricating oil passage through an existing oil pump to lubricate components such as the bearings inside the vacuum pump. By arranging an oil passage hole on the stationary ring to communicate the oil passage hole with the lubricating oil passage, arranging a lubricating groove in the shape of a fishbone connected end to end on the end face where the moving ring and the stationary ring abut, communicating the oil passage hole with it, and setting the maximum and minimum radial dimensions of the lubricating groove, the end face of the stationary ring can block the outer edge part of the entire lubricating groove and expose part of the lubricating groove inside the inner edge of the stationary ring. Then, an oil outlet passage communicating with the lubricating oil chamber is arranged between the inner hole of the retaining frame where the stationary ring is located and the rotating shaft. In this way, the lubricating oil enters the lubricating groove from the lubricating oil passage through the oil passage hole. Since the outer edge of the lubricating groove is blocked by the end face of the stationary ring, the entering lubricating oil can flow outward to the groove in the outer edge area of the lubricating groove under the centrifugal force of the rotating moving ring, and the lubricating oil can penetrate into the joint surface of the moving ring and the stationary ring to form an oil film. And the lubricating oil continuously enters and gradually fills the lubricating groove from the outside to the inside before flowing out from the part where the inner edge of the stationary ring is exposed, effectively ensuring that there is always sufficient lubricating oil in the lubricating groove area during operation to guarantee continuous lubrication effect. And the flowing out lubricating oil can absorb and continuously take away the heat generated by the friction between the moving ring and the stationary ring and flow back to the lubricating oil chamber through the oil outlet passage to realize circulation, thereby avoiding the temperature of the moving ring and the stationary ring being too high, which affects the lubrication effect and causes sealing failure.

[0009] In the shaft seal structure of the above-mentioned medical anti-corrosion screw vacuum pump, the lubrication groove includes an annular main bone segment and a strip-shaped branch segment connected to the inner and outer sides of the main bone segment, and the outer ends of the branch segments on both sides of the main bone segment are tilted toward the same side and arranged in an eight-shaped shape along the circumferential direction of the main bone segment. This is conducive to the dynamic ring rotating along the outer end of the branch segment when the vacuum pump is working. When the dynamic ring accelerates, the lubricating oil entering the lubrication groove will be affected by inertia and will be sent back to the main bone segment along the inner wall slope of the branch segment. With the centrifugal effect, it can more effectively avoid the lubricating oil directly flowing out from the outer end of the branch segment inside the main bone segment during this process. When the dynamic ring decelerates, the lubricating oil in the outer branch segment will flow toward the outer end along the branch segment slope, thereby ensuring that the lubricating oil is maintained in the branch segment, so that more lubricating oil is kept in the lubrication groove to avoid insufficient lubricating oil supply after deceleration conditions to affect the lubrication effect. In addition, it also avoids the sharp edge of the lubrication groove from scratching the end face of the static ring along the rotation direction, thereby extending the life of the components.

[0010] In the shaft seal structure of the medical anti-corrosion screw vacuum pump, the end face of the static ring has a circular groove arranged in the circumferential direction, the oil hole is connected to the groove, and the groove is directly connected to the main bone segment. This is conducive to the shallow lubrication groove to quickly and evenly spread the lubricating oil added through the oil hole to various parts of the main bone segment through the groove, so as to achieve uniform lubrication of the dynamic ring and the static ring in the circumferential direction and ensure the lubrication effect.

[0011] In the shaft seal structure of the medical anti-corrosion screw vacuum pump, the static ring has a plurality of oil holes, which are evenly spaced along the circumference of the static ring. The plurality of oil holes facilitates the lubricating oil to be more evenly and quickly diffused to all parts of the groove, thereby ensuring lubrication uniformity and lubricating oil replenishment speed.

[0012] In the shaft seal structure of the above-mentioned medical anti-corrosion screw vacuum pump, the end face of the retaining frame has an annular groove, the static ring is axially slidably embedded in the groove, the port of the lubricating oil circuit is located at the bottom of the groove, and a plurality of compression springs are arranged in the groove, the two ends of the compression spring act on the static ring and the bottom of the groove respectively, and the two ends of the compression spring are respectively opposite to the oil hole and the port of the lubricating oil circuit. In this way, the axial movement of the static ring can obtain the guiding effect of the groove to stabilize its feeding direction, and the compression spring can ensure that the static ring continues to abut against the end face of the dynamic ring for sealing, and the two ends of the compression spring are respectively opposite to the oil hole and the port of the lubricating oil circuit in the groove, so that the lubricating oil entering from the lubricating oil circuit can directly pass into the oil hole through the inner cavity of the compression spring without being affected by the interference of the compression of the compression spring, thereby ensuring stable lubrication.

[0013] In the shaft seal structure of the medical anti-corrosion screw vacuum pump, the side cover further includes an annular cooling water jacket, which is arranged around the periphery of the retainer, and the inner cavity of the cooling water jacket is connected to the outer peripheral surface of the retainer. The cooling water jacket can provide a circulating cooling effect to the retainer from the outside, so that the lubricating oil entering the slide groove can also be cooled to a certain extent, and the lubricating oil there can absorb more heat after being sent to between the dynamic ring and the static ring through the oil hole, thereby improving the heat dissipation effect.

[0014] In the shaft seal structure of the medical anti-corrosion screw vacuum pump, the bottom surface of the chute also has a cooling groove that is recessed toward the side away from the stationary ring. This can further increase the inner wall surface area of the chute, which is conducive to allowing the incoming lubricating oil to more fully exchange heat with the coolant in the cooling water jacket, thereby achieving lubricating oil cooling and ensuring the lubrication and cooling effect.

[0015] In the shaft seal structure of the medical anti-corrosion screw vacuum pump, the outer edge of the end face where the moving ring and the static ring abut against each other has a plurality of filling grooves arranged at intervals around the circumference, the filling grooves are separated from the lubrication grooves, and the openings of the filling grooves along the radial direction of the moving ring are all deflected to the same side. This is conducive to the small molecule cleaning medium outside the moving ring to enter the filling groove, maintaining a good sealing environment between the moving ring and the static ring, and when the moving ring rotates, the cleaning medium in the filling groove can be thrown out to continuously take away heat, thereby ensuring the lubrication effect.

[0016] Compared with the prior art, the advantages of the present invention are as follows:

[0017] In the medical anti-corrosion screw vacuum pump, the lubricating oil enters the lubricating groove from the lubricating oil path through the oil hole. Since the outer edges of the lubricating grooves in a fishbone shape are blocked by the end faces of the static rings, the lubricating oil entering can flow outward to the grooves in the outer edge area of the lubricating grooves under the centrifugal action of the rotating moving ring, and the lubricating oil can penetrate into the joint surface of the moving ring and the static ring to form an oil film. The lubricating oil continuously enters and gradually fills the lubricating groove from the outside to the inside before flowing out from the part exposed to the inner edge of the static ring, effectively ensuring a continuous lubrication effect. The flowing lubricating oil can absorb heat and flow back into the lubricating oil cavity to realize circulation, thereby ensuring a continuous and stable sealing effect of the moving ring and the static ring, so that when it is used in the medical and chemical fields to evacuate corrosive media, it can better prevent corrosive media from entering the gear assembly of the screw vacuum pump, thereby making the vacuum pump have better anti-corrosion performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a partial cross-sectional schematic diagram of this embodiment.

[0019] Figure 2 yes Figure 1 Enlarged view of part A in .

[0020] Figure 3Yes Figure 1 An enlarged view of part B in

[0021] Figure 4 It is a schematic structural view of the cross-section of the moving ring in this embodiment.

[0022] Figure 5 It is a schematic structural view of the end face of the stationary ring in this embodiment.

[0023] Figure 6 It is a schematic perspective view of the moving ring in this embodiment.

[0024] Figure 7 It is a schematic perspective view of the stationary ring in this embodiment.

[0025] In the figure, 1 is the side cover; 11 is the lubricating oil chamber; 12 is the cage; 121 is the chute; 122 is the cooling groove; 13 is the cooling water jacket; 14 is the exhaust port; 2 is the rotating shaft; 3 is the lubricating oil path; 4 is the moving ring; 41 is the lubricating groove; 411 is the main bone section; 412 is the branch section; 42 is the filling groove; 5 is the stationary ring; 51 is the oil through hole; 52 is the groove; 6 is the oil outlet channel; 7 is the compression spring part; 8 is the driving motor; 9 is the gear assembly; 10 is the housing; 101 is the oil outlet chamber. Specific Embodiments

[0026] The following are specific embodiments of the present invention and in combination with the accompanying drawings, the technical solutions of the present invention are further described, but the present invention is not limited to these embodiments.

[0027] As Figure 1-7As shown, the medical anti-corrosion screw vacuum pump includes a casing 10, a side cover 1, a drive motor 8, a gear assembly 9 and a rotating shaft 2. The rotating shaft 2 is horizontally inserted into the side cover 1, and the exhaust port of the vacuum pump is located on the side cover 1. The end of the rotating shaft 2 is transmission-connected with the drive motor 8 through the existing gear assembly 9, so that the drive motor 8 can drive the rotating shaft 2 to rotate. The side cover 1 is provided with a lubricating oil circuit 3 and a lubricating oil chamber 11 for supplying oil to the lubricating oil circuit 3. The shaft seal structure includes a coaxially arranged dynamic ring 4 and a static ring 5. The dynamic ring 4 is fixedly sleeved on the outer periphery of the rotating shaft 2. The side cover 1 includes an annular retaining frame 12. The static ring 5 is coaxially slidably embedded in one end of the retaining frame 12 and always has a tendency to move toward the dynamic ring 4. The end face of the dynamic ring 4 facing the static ring 5 has a circumferentially arranged lubricating groove 41. The lubricating groove The cross section of 41 is in the shape of a fishbone connected end to end. The maximum radial dimension of the outer edge of the lubrication groove 41 is smaller than the outer diameter dimension of the end face of the stationary ring 5 and larger than the inner diameter dimension of the end face of the stationary ring 5. The minimum radial dimension of the outer edge of the lubrication groove 41 is smaller than the inner diameter dimension of the end face of the stationary ring 5. The depth range of the lubrication groove 41 is 0.005mm-0.01mm. The end face of the stationary ring 5 has an oil hole 51. The oil outlet end of the oil hole 51 is connected to the lubrication groove 41. The oil inlet end of the oil hole 51 is connected to the lubrication oil circuit 3. An annular oil outlet cavity 101 is formed between the inner edge of the stationary ring 5 and the rotating shaft 2 and is directly connected to the lubrication groove 41. An annular oil outlet channel 6 is formed between the inner hole of the retaining frame 12 and the rotating shaft 2. The two ends of the oil outlet channel 6 are respectively connected to the oil outlet cavity 101 and the lubrication oil cavity 11. The lubricating oil circuit 3 can be an existing structure inside the side cover 1. The lubricating oil chamber 11 is used to store lubricating oil. The lubricating oil in the lubricating oil chamber 11 can be pressurized and sent to the lubricating oil circuit 3 through an existing oil pump to lubricate the bearings and other components inside the vacuum pump. The lubricating groove 41 includes an annular main bone segment 411 and a strip-shaped branch segment 412 connected to the inside and outside of the main bone segment 411. There are twenty branch segments 412 on both sides of the main bone segment 411. The outer ends of the branch segments 412 on both sides of the main bone segment 411 are tilted to the same side and are arranged in an eight-shaped shape along the circumference of the main bone segment 411. The end face of the stationary ring 5 has a ring-shaped groove 52 arranged around the circumference, and the oil hole 51 is connected to the groove 52. The groove 52 is directly connected to the main bone segment 411. There are six oil holes 51 on the stationary ring 5, and the six oil holes 51 are evenly spaced along the circumference of the stationary ring 5. The end face of the retainer 12 has an annular slide groove 121, the stationary ring 5 is axially slidably embedded in the slide groove 121, and the inner and outer edges of the stationary ring 5 are provided with existing sealing rings to form a seal with the inner wall of the slide groove 121. Six compression springs 7 are provided in the slide groove 121, and the two ends of the compression springs 7 act on the stationary ring 5 and the bottom surface of the slide groove 121 respectively. The port of the lubricating oil circuit 3 is located on the bottom surface of the slide groove 121, and the oil hole 51 and the port of the lubricating oil circuit 3 are coaxially arranged with the compression spring 7. The side cover 1 also includes an annular cooling water jacket 13, which is arranged around the outer periphery of the retainer 12, and the inner cavity of the cooling water jacket 13 is connected to the outer peripheral surface of the retainer 12.The bottom surface of the slide groove 121 also has a cooling groove 122 formed by being recessed toward the side away from the stationary ring 5. The outer edge of the end surface where the dynamic ring 4 and the stationary ring 5 abut against each other has twenty filling grooves 42 arranged at intervals around the circumference, the filling grooves 42 are separated from the lubrication grooves 41, and the openings of the filling grooves 42 along the radial direction of the dynamic ring 4 are all deflected toward the same side.

[0028] During the operation of the medical anti-corrosion screw vacuum pump, the rotating shaft 2 drives the moving ring 4 to rotate at a high speed, and the static ring 5 maintains a stable contact between the end face and the moving ring 4 under the action of the spring member. The high-pressure lubricating oil in the lubricating oil circuit 3 enters the slide groove 121 and is sent to the lubrication groove 41 of the moving ring 4 through the oil hole 51 on the static ring 5. The lubricating oil in the lubrication groove 41 soaks the contact surface of the moving ring 4 and the static ring 5 to form an oil film, thereby reducing the friction between the moving ring 4 and the static ring 5. At the same time, after filling the lubrication groove 41, the lubricating oil can be continuously discharged from the outer end of the branch segment 412 on the inner side of the main bone segment 411, and reflux to the lubricating oil chamber 11 along the oil outlet channel 6, taking away the heat generated by the friction between the moving ring 4 and the static ring 5 to achieve a cooling effect, so as to ensure a stable sealing effect, better avoid the medical corrosive medium from entering the gear assembly 9 of the screw vacuum pump during vacuum extraction, and make the vacuum pump have better anti-corrosion performance.

[0029] The specific embodiments described herein are merely examples of the spirit of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in similar ways, but they will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

Claims

1. The shaft seal structure of a medical anti-corrosion screw vacuum pump. The vacuum pump includes a casing (10), a side cover (1) and a rotating shaft (2). There is a lubricating oil passage (3) and a lubricating oil chamber (11) for supplying oil to the lubricating oil passage (3) inside the side cover (1). The shaft seal structure includes a dynamic ring (4) and a static ring (5) arranged coaxially. The dynamic ring (4) is fixedly sleeved on the outer periphery of the rotating shaft (2). The side cover (1) includes an annular cage (12). The static ring (5) is coaxially and slidably embedded at one end of the cage (12) and always has a tendency to move towards the dynamic ring (4). It is characterized in that, The end surface of the moving ring (4) facing the stationary ring (5) has a lubricating groove (41) arranged in a circumferential direction. The cross section of the lubricating groove (41) is in a herringbone shape connected end to end. The maximum radial dimension of the outer edge of the lubricating groove (41) is smaller than the outer diameter dimension of the end surface of the stationary ring (5) and larger than the inner diameter dimension of the end surface of the stationary ring (5). The minimum radial dimension of the outer edge of the lubricating groove (41) is smaller than the inner diameter dimension of the end surface of the stationary ring (5). The end surface of the stationary ring (5) has an oil through hole (51). The oil outlet end of the oil hole (51) is connected to the lubricating groove (41), and the oil inlet end of the oil hole (51) is connected to the lubricating oil path (3). An oil outlet cavity (101) connected to the lubricating groove (41) is formed between the inner edge of the stationary ring (5) and the rotating shaft (2). An annular oil outlet channel (6) is formed between the inner hole of the retaining frame (12) and the rotating shaft (2), and two ends of the oil outlet channel (6) are respectively connected to the oil outlet cavity (101) and the lubricating oil cavity (11).

2. The shaft seal structure of the medical anti-corrosion screw vacuum pump according to claim 1, characterized in that, The lubricating groove (41) comprises an annular main bone segment (411) and strip-shaped branch segments (412) connected to the inner and outer sides of the main bone segment (411); the outer ends of the branch segments (412) on both sides of the main bone segment (411) are inclined toward the same side and arranged in an eight-shaped shape along the circumference of the main bone segment (411).

3. The shaft seal structure of the medical anti-corrosion screw vacuum pump according to claim 1 or 2, characterized in that, The end surface of the stationary ring (5) has a groove (52) arranged in an annular shape around the circumference, the oil hole (51) is connected to the groove (52), and the groove (52) is directly connected to the main bone segment (411).

4. The shaft seal structure of the medical anti-corrosion screw vacuum pump according to claim 3, characterized in that, The stationary ring (5) is provided with a plurality of oil through holes (51), and the plurality of oil through holes (51) are evenly spaced and arranged along the circumference of the stationary ring (5).

5. The shaft seal structure of the medical anti-corrosion screw vacuum pump according to claim 1 or 2, characterized in that, The end surface of the retaining frame (12) has an annular slide groove (121), the stationary ring (5) is axially slidably embedded in the slide groove (121), the port of the lubricating oil circuit (3) is located at the bottom surface of the slide groove (121), and a plurality of compression spring members (7) are arranged in the slide groove (121), the two ends of the compression spring member (7) respectively act on the stationary ring (5) and the bottom surface of the slide groove (121), and the two ends of the compression spring member (7) are respectively opposite to the oil hole (51) and the port of the lubricating oil circuit (3).

6. The shaft seal structure of the medical anti-corrosion screw vacuum pump according to claim 5, characterized in that, The side cover (1) further comprises an annular cooling water jacket (13), the cooling water jacket (13) being arranged around the periphery of the retaining frame (12), and the inner cavity of the cooling water jacket (13) being connected to the outer peripheral surface of the retaining frame (12).

7. The shaft seal structure of the medical anti-corrosion screw vacuum pump according to claim 6, characterized in that, The bottom surface of the slide groove (121) also has a cooling groove (122) which is recessed toward the side away from the stationary ring (5).

8. The shaft seal structure of the medical anti-corrosion screw vacuum pump according to claim 1 or 2, characterized in that, The outer edge of the end surface where the moving ring (4) and the stationary ring (5) abut against each other has a plurality of filling grooves (42) arranged at intervals around the circumference, the filling grooves (42) are separated from the lubrication grooves (41), and the openings of the filling grooves (42) along the radial direction of the moving ring (4) are all deflected to the same side.

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