A screw vacuum pump with anti-backflow function

Abstract

The present invention belongs to the technical field of vacuum pumps. It solves the problem in the prior art that the pumping speed of a screw vacuum pump decreases due to backflow. A backflow-proof screw vacuum pump is provided, including a pump body and a screw. Two floating pressure rings made of wear-resistant self-lubricating material are arranged on the inner wall of one end of the exhaust port of the pump body. The floating pressure ring is C-shaped and the openings of the two floating pressure rings are arranged opposite to each other. There is a floating gap between the two ends of the two floating pressure rings on the same side. An elastic ring capable of elastic deformation is fixed against the outer wall of the floating pressure ring. A plurality of compression springs are arranged along the circumference of the pump body. Each of the compression springs is arranged along the radial direction of the floating pressure ring, and the inner end of each compression spring is connected to the elastic ring on the corresponding floating pressure ring so that the two floating pressure rings are respectively against the screw teeth of the two screws. The present invention can solve the backflow problem of the screw vacuum pump while ensuring the working stability of the screw vacuum pump.

Description

Technical Field

[0001] The invention belongs to the technical field of vacuum pumps and relates to a backflow-proof screw vacuum pump. Background Art

[0002] When the screw vacuum pump is working, gas enters the vacuum pump from the air inlet, and then the gas is compressed by the rotation of the screw in the vacuum pump. Finally, the gas is gradually discharged from the vacuum pump from the air outlet as the screw moves. As the gas is compressed, the gas pressure in the vacuum pump increases continuously from the air inlet to the air outlet. The increasing gas pressure will give a reaction force to the gas behind, causing part of the gas in the vacuum pump to tend to reflux, that is, part of the gas will reflux from the gap between the pump body and the screw. This part of the reflux gas will produce a reverse thrust on the screw, thereby reducing the pumping speed of the screw vacuum pump.

[0003] In order to solve the above problems, the current common practice is to increase the speed of the screw, but this creates new problems. When the screw moves at high speed, it is easy to heat up due to friction. When the surface temperature of the screw rises, the screw will expand due to thermal expansion and contraction and further increase friction, thereby accelerating the wear of the screw. The worn screw will produce a large amplitude vibration when moving at high speed. The large amplitude vibration will cause aging and damage to the sealing components on the equipment, thereby affecting the air tightness of the equipment. These factors will reduce the working stability of the screw vacuum pump. Summary of the invention

[0004] The purpose of the present invention is to solve the above problems in the prior art and to propose a screw vacuum pump with anti-backflow. The technical problem to be solved by the present invention is to solve the backflow problem of the screw vacuum pump while ensuring the working stability of the screw vacuum pump.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] A screw vacuum pump for preventing backflow comprises a pump body with an air inlet and an air outlet, wherein two screws meshing with each other are rotatably arranged in the pump body, and characterized in that a connecting pipe connecting the inner cavity of the pump body and the air outlet is arranged on the side wall of the pump body close to the air inlet, and a second overflow valve for unidirectionally conducting the air flow in the connecting pipe to the air outlet is arranged in the connecting pipe, and two floating pressure rings made of wear-resistant self-lubricating material are arranged on the inner wall of one end of the air outlet of the pump body, the floating pressure ring is C-shaped and the openings of the two floating pressure rings are arranged oppositely, and there is a floating gap between the two ends of the two floating pressure rings on the same side, and an elastic ring capable of elastic deformation is fixedly attached to the outer side wall of the floating pressure ring, and a plurality of compression springs are arranged along the circumference of the pump body, each of the compression springs is arranged along the radial direction of the floating pressure ring, and the inner end of each compression spring is connected to the elastic ring on the corresponding floating pressure ring so that the two floating pressure rings are respectively against the screw teeth of the two screws.

[0007] When the pressure in the pump chamber at the front end of the pump body rises above a preset value, the airflow in the pump chamber at the front end can be pushed open by the second overflow valve in the connecting pipe and discharged directly to the exhaust port of the pump body through the connecting pipe, thereby reducing the temperature rise in the pump chamber, thereby ensuring the working stability of the screw vacuum pump. The two C-shaped floating pressure rings of the anti-backflow screw vacuum pump can match the outer contour of the two mutually meshing screw threads in the pump body, and there is a floating gap between the two floating pressure rings with openings arranged opposite to each other, so that the two floating pressure rings will not interfere with each other during movement. Furthermore, the elastic ring absorbs a plurality of compression springs. After the pressure is applied to it, the "point-to-point" pressure can be converted into "face-to-face" pressure, that is, the elastic ring of the anti-backflow screw vacuum pump can evenly apply the pressure of the compression spring to the floating pressure ring, so that the two floating pressure rings made of wear-resistant self-lubricating material can be more closely attached to the thread teeth of the two screws, thereby effectively preventing the gas in the part of the pump body close to the exhaust port from flowing back from the gap between the pump body and the screw under the action of high pressure, without the need to continuously increase the speed of the screw in the traditional way, thereby solving the backflow problem of the screw vacuum pump while ensuring the working stability of the screw vacuum pump.

[0008] In the above-mentioned anti-backflow screw vacuum pump, a first annular mounting groove is provided on the inner wall of the pump body, the floating pressure ring is arranged in the first mounting groove, and the pump body is axially plugged with an annular sleeve at the exhaust port end, the inner side surface of the sleeve is arranged flush with the inner wall surface of the pump body, and there is a sliding distance between the floating pressure ring and the sleeve. By providing the sleeve, the disassembly and assembly of the floating pressure ring can be facilitated, and by arranging the inner side surface of the sleeve flush with the inner wall surface of the pump body, the sleeve and the screw in the pump body are prevented from forming motion interference, thereby ensuring the working stability of the screw vacuum pump. At the same time, the sliding distance enables the floating pressure ring to achieve a certain amount of sliding along the axial direction of the pump body after being installed in the first mounting groove of the pump body, so that the floating pressure ring can better form a floating seal with the corresponding screw thread, reduce the friction and collision contact between the floating pressure ring and the screw, thereby solving the backflow problem of the screw vacuum pump while ensuring the working stability of the screw vacuum pump.

[0009] In the above-mentioned anti-backflow screw vacuum pump, the pump body includes an air intake section and an air exhaust section connected front and back, and the pump body is also provided with a second annular mounting groove on one side of the connection between the air intake section and the air exhaust section and the sleeve is axially inserted, and a sealing ring is also provided at the connection between the air intake section and the air exhaust section of the pump body, and the sealing ring is located on the outside of the sleeve, and the second mounting groove is also provided with two floating pressure rings with the elastic ring fixed against the outer wall. Dividing the pump body into an air intake section and an air outlet section connected front and back can facilitate the processing and manufacturing of the pump body, and the provision of a sealing ring can avoid air leakage at the connection between the air intake section and the air outlet section. When the screw vacuum pump is working, as the gas is continuously compressed in the pump body, the gas pressure in the middle of the pump body will also change significantly. By adding the floating pressure ring, the elastic ring and a plurality of compression springs in the second mounting groove of the pump body, the backflow problem in the middle of the screw vacuum pump body can be better solved.

[0010] In the above-mentioned anti-backflow screw vacuum pump, the inlet of the connecting pipe is arranged between the second mounting groove and the air inlet, so that the connecting pipe can cooperate with the two floating pressure rings located in the middle of the pump body (the connection between the air inlet section and the exhaust section of the pump body), so that the pressure generated inside the screw vacuum pump is kept within a reasonable range, thereby solving the backflow problem of the screw vacuum pump while ensuring the working stability of the screw vacuum pump.

[0011] In the above-mentioned anti-backflow screw vacuum pump, the pump body is provided with an overflow channel connecting the inner cavity of the pump body and the exhaust port on the side wall near the exhaust port, the inlet of the overflow channel is arranged adjacent to the inner side of the floating pressure ring located at one end of the exhaust port, and a first overflow valve for unidirectionally conducting the gas in the overflow channel to the exhaust port is arranged in the overflow channel. The pressure of the gas at the exhaust port of the pump body mainly comes from two aspects, one is the pressure of the external environment, and the other is the pressure generated by the continuous compression of the gas inside the pump body. By setting the overflow channel, when the pressure of the rear end pump chamber of the pump body rises above the preset value, the gas in the rear end pump chamber can be directly discharged to the exhaust port of the pump body through the overflow channel by opening the first overflow valve in the overflow channel, thereby reducing the temperature rise in the pump chamber and keeping the pressure of the rear end pump chamber of the pump body within a reasonable range, thereby ensuring the working stability of the screw vacuum pump, and at the same time, it can also reduce the sealing pressure of the two floating pressure rings located in the middle of the pump body, thereby ensuring the working stability of the screw vacuum pump and solving the backflow problem of the screw vacuum pump.

[0012] In the above-mentioned anti-backflow screw vacuum pump, the pump body is provided with a mounting hole, the compression spring is arranged in the mounting hole, the inner end of the compression spring is connected to the elastic ring, the outer end of the compression spring is connected to a plug, and the plug is threadedly connected to the hole wall of the mounting hole. The compression spring is hidden in the pump body, and the hole wall of the mounting hole can play a limiting and guiding role for the compression spring. More importantly, the plug threadedly connected to the hole wall of the mounting hole can block the mounting hole, and the pre-compression amount of the spring can be adjusted by rotating the plug, so that the compression spring can stably act on the elastic ring, thereby ensuring that the elastic ring can evenly apply the pressure of the compression spring to the floating pressure ring.

[0013] In the above-mentioned anti-backflow screw vacuum pump, the pump body has an annular positioning groove, the outer end of the sleeve has a flange portion, the flange portion is embedded in the positioning groove, and the inner end surface of the sleeve is flush with the wall surface of the first installation groove or the second installation groove near the exhaust port. The flange portion is embedded in the positioning groove so that the sleeve can be more firmly set on the pump body, avoiding displacement of the sleeve due to force during operation, and at the same time, the inner end surface of the sleeve can replace the groove wall of the first installation groove or the second installation groove near the exhaust port.

[0014] In the above-mentioned anti-backflow screw vacuum pump, the size of the elastic ring is greater than or equal to the size of the floating pressure ring, and the elastic ring covers and is fixed to the outer surface of the floating pressure ring, so that the pressure of the compression spring acting on the elastic ring can act more evenly on the floating pressure ring.

[0015] In the above-mentioned anti-backflow screw vacuum pump, a plurality of compression springs are evenly spaced along the circumference of the pump body, so that the pressure of the compression springs acting on the elastic ring can act more evenly on the floating pressure ring.

[0016] Compared with the prior art, the advantages of the anti-backflow screw vacuum pump are: the elastic ring of the anti-backflow screw vacuum pump can evenly apply the pressure of the compression spring to the floating pressure ring, so that the two floating pressure rings made of wear-resistant self-lubricating material can be more closely attached to the thread teeth of the two screws, thereby effectively preventing the gas in the part of the pump body close to the exhaust port from flowing back from the gap between the pump body and the screw under the action of high pressure, thereby solving the backflow problem of the screw vacuum pump while ensuring the working stability of the screw vacuum pump. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural schematic diagram of the anti-backflow screw vacuum pump.

[0018] Figure 2 yes Figure 1 Cross-sectional view at AA after removing the screw.

[0019] Figure 3 yes Figure 2 A partial enlarged view of point A in the middle.

[0020] Figure 4 It is a cross-sectional view of the screw vacuum pump for preventing backflow.

[0021] Figure 5 yes Figure 4 A partial enlarged view of point B in the middle.

[0022] Figure 6 yes Figure 4 A partial enlarged view of point C in the middle.

[0023] In the figure, 1, pump body; 1a, air inlet section; 1b, exhaust section; 1c, air inlet; 1d, exhaust port; 1e, first mounting groove; 1f, positioning groove; 1g, second mounting groove; 2, screw; 3, floating pressure ring; 4, floating gap; 5, elastic ring; 6, compression spring; 7, sleeve; 7a, flange portion; 8, sliding spacing; 9, sealing ring; 10, overflow channel; 11, first overflow valve; 12, connecting pipe; 13, second overflow valve; 14, mounting hole; 15, screw plug. DETAILED DESCRIPTION

[0024] The following are specific embodiments of the present invention and the accompanying drawings to further describe the technical solution of the present invention, but the present invention is not limited to these embodiments.

[0025] Embodiment 1

[0026] A screw vacuum pump with anti-backflow function, referring to Figure 1-6 , comprising a pump body 1 having an air inlet 1c and an air outlet 1d, wherein two mutually meshing screws 2 are rotatably arranged in the pump body 1, a connecting pipe 12 connecting the inner cavity of the pump body 1 and the air outlet 1d is arranged on the side wall of the pump body 1 close to the air inlet 1c, and a second overflow valve 13 for unidirectionally conducting the air flow in the connecting pipe 12 to the air outlet 1d is arranged in the connecting pipe 12, and two floating pressure rings 3 made of wear-resistant self-lubricating material are arranged on the inner wall of one end of the air outlet 1d of the pump body 1, and the floating pressure ring 3 is in the shape of a C The openings of the two floating pressure rings 3 are arranged opposite to each other, and there is a floating gap 4 between the two ends of the two floating pressure rings 3 on the same side. An elastic ring 5 that can undergo elastic deformation is fixed on the outer wall of the floating pressure ring 3, and a plurality of compression springs 6 are arranged along the circumference of the pump body 1. Each of the compression springs 6 is arranged along the radial direction of the floating pressure ring 3, and the inner end of each compression spring 6 is connected to the elastic ring 5 on the corresponding floating pressure ring 3 so that the two floating pressure rings 3 are respectively against the screw teeth of the two screws 2.

[0027] Specifically, refer to Figure 4 The pump body 1 includes an intake section 1a and an exhaust section 1b connected front and back, and the pump body 1 is also provided with an annular second installation groove 1g on one side of the connection between the intake section 1a and the exhaust section 1b and the insert sleeve 7 is axially inserted therein, and a sealing ring 9 is also provided at the connection between the intake section 1a and the exhaust section 1b of the pump body 1, and the sealing ring 9 is located on the outside of the insert sleeve 7, and the second installation groove 1g is also provided with two floating pressure rings 3 whose outer side walls are abutted and fixed with the elastic ring 5.

[0028] More specifically, refer to Figure 1-5 , the pump body 1 has an annular positioning groove 1f, the outer end of the insert sleeve 7 has a flange portion 7a, the flange portion 7a is embedded in the positioning groove 1f, and the inner end surface of the insert sleeve 7 is flush with the wall surface of the first mounting groove 1e or the second mounting groove 1g close to the exhaust port 1d; the pump body 1 has a mounting hole 14, the compression spring 6 is arranged in the mounting hole 14, the inner end of the compression spring 6 is connected to the elastic ring 5, the outer end of the compression spring 6 is connected to a plug 15, and the plug 15 is threadedly connected to the hole wall of the mounting hole 14. In this embodiment, it is preferred that the size of the elastic ring 5 is greater than or equal to the size of the floating pressure ring 3, and the elastic ring 5 covers and is fixed to the outer surface of the floating pressure ring 3; it is preferred that a plurality of compression springs 6 are evenly spaced along the circumference of the pump body 1.

[0029] Further, refer to Figure 1-6A first annular mounting groove 1e is provided on the inner wall of the pump body 1, and the floating pressure ring 3 is arranged in the first mounting groove 1e. An annular insert sleeve 7 is axially inserted at the exhaust port 1d end of the pump body 1. The inner side surface of the insert sleeve 7 is flush with the inner wall surface of the rest of the pump body 1, and a sliding spacing 8 is provided between the floating pressure ring 3 and the insert sleeve 7.

[0030] Furthermore, refer to Figure 4 , the inlet of the connecting pipe 12 is arranged between the second mounting groove 1g and the air inlet 1c. Figure 4 The pump body 1 is provided with an overflow channel 10 connecting the inner cavity of the pump body 1 and the exhaust port 1d on the side wall near the exhaust port 1d, the inlet of the overflow channel 10 is arranged adjacent to the inner side of the floating pressure ring 3 located at one end of the exhaust port 1d, and a first overflow valve 11 is arranged in the overflow channel 10 for unidirectionally conducting the air flow in the overflow channel 10 to the exhaust port 1d.

[0031] The two C-shaped floating pressure rings 3 of the anti-backflow screw vacuum pump can match the outer contour of the threads of the two mutually meshing screws 2 in the pump body 1, and there is a floating gap 4 between the two floating pressure rings 3 with openings arranged opposite to each other, so that the two floating pressure rings 3 will not interfere with each other during movement. Furthermore, after absorbing the pressure of a number of compression springs 6, the elastic ring 5 can convert the "point-to-point" pressure into a "face-to-face" pressure, that is, the elastic ring 5 of the anti-backflow screw vacuum pump can evenly apply the pressure of the compression springs 6 to the floating pressure ring 3, so that the two floating pressure rings 3 made of wear-resistant self-lubricating material can be more closely attached to the threads of the corresponding screws 2, thereby effectively preventing part of the gas in the pump body 1 from flowing back from the gap between the pump body 1 and the screw 2 under the action of high pressure;

[0032] When the screw vacuum pump is working, the pressure of the gas at the exhaust port 1d of the pump body 1 mainly comes from two aspects. On the one hand, it is the pressure of the external environment, and on the other hand, it is the pressure generated by the continuous compression of the gas inside the pump body 1. The two floating pressure rings 3 arranged at one end of the pump body 1 close to the exhaust port 1d can solve the problem of part of the gas at the exhaust port 1d of the pump body 1 flowing back from the gap between the pump body 1 and the screw 2 under the action of high pressure; in addition, as the gas is continuously compressed in the pump body 1, the gas pressure in the middle of the pump body 1 will also change significantly, and the two floating pressure rings 3 arranged in the middle of the pump body 1 can solve the problem of part of the gas in the middle of the pump body 1 flowing back from the gap between the pump body 1 and the screw 2 under the action of high pressure.

[0033] Furthermore, the screw vacuum pump is also provided with an overflow channel 10 at the position of the floating pressure ring 3 at the exhaust port 1d end of the pump body 1. The overflow channel 10 can form a complementary match with the floating pressure ring 3 at the position, so that when the pressure of the rear end pump chamber of the pump body 1 rises to exceed a preset value, the airflow in the rear end pump chamber can open the first overflow valve 11 in the overflow channel 10 and be directly discharged to the exhaust port 1d of the pump body 1 through the overflow channel 10, thereby reducing the increase in the temperature in the pump chamber and keeping the pressure of the rear end pump chamber of the pump body 1 within a reasonable range, thereby ensuring the working stability of the screw vacuum pump, and further solving the problem of the screw vacuum pump while ensuring the working stability of the screw vacuum pump. Reflux problem; at the same time, the screw vacuum pump is also equipped with a connecting pipe 12 at a position adjacent to the floating pressure ring 3 in the middle of the pump body 1, and the connecting pipe 12 can also form a complementary match with the floating pressure ring 3 thereat. When the pressure in the pump chamber at the front end of the pump body 1 rises above a preset value, the airflow in the pump chamber at the front end can be pushed open by the second overflow valve 13 in the connecting pipe 12 and discharged directly to the exhaust port 1d of the pump body 1 through the connecting pipe 12, thereby reducing the increase in temperature in the pump chamber and keeping the pressure generated inside the screw vacuum pump within a reasonable range, thereby ensuring the working stability of the screw vacuum pump, and further solving the reflux problem of the screw vacuum pump while ensuring the working stability of the screw vacuum pump.

[0034] 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. A screw vacuum pump for preventing backflow, comprising a pump body (1) having an air inlet (1c) and an air outlet (1d), wherein two screws (2) are rotatably arranged in the pump body (1) and mesh with each other, and characterized in that: A connecting pipe (12) connecting the inner cavity of the pump body (1) and the exhaust port (1d) is arranged on the side wall of the pump body (1) near the air inlet (1c), and a second overflow valve (13) is arranged in the connecting pipe (12) for unidirectionally conducting the air flow in the connecting pipe (12) to the exhaust port (1d). Two floating pressure rings (3) made of wear-resistant self-lubricating material are arranged on the inner wall of one end of the exhaust port (1d) of the pump body (1), and the floating pressure rings (3) are C-shaped and the openings of the two floating pressure rings (3) are arranged opposite to each other. The floating pressure ring (3) has a floating gap (4) between its two ends located on the same side, and an elastic ring (5) capable of elastic deformation is fixedly attached to the outer wall of the floating pressure ring (3). The pump body (1) is provided with a plurality of compression springs (6) along its circumference, and each of the compression springs (6) is arranged along the radial direction of the floating pressure ring (3), and the inner end of each compression spring (6) is connected to the elastic ring (5) on the corresponding floating pressure ring (3) so that the two floating pressure rings (3) are respectively abutted against the threads of the two screws (2).

2. The anti-backflow screw vacuum pump according to claim 1, characterized in that: The inner wall of the pump body (1) is provided with a first annular mounting groove (1e), the floating pressure ring (3) is arranged in the first mounting groove (1e), and the pump body (1) is axially plugged with an annular insert (7) at the exhaust port (1d) end, the inner side surface of the insert (7) is flush with the inner wall surface of the pump body (1), and a sliding spacing (8) is provided between the floating pressure ring (3) and the insert (7).

3. The anti-backflow screw vacuum pump according to claim 2, characterized in that: The pump body (1) comprises an air intake section (1a) and an air exhaust section (1b) connected front and rear, and the pump body (1) is provided with a second annular mounting groove (1g) on ​​one side of the connection between the air intake section (1a) and the air exhaust section (1b) and is axially plugged with the insert sleeve (7). A sealing ring (9) is also provided at the connection between the air intake section (1a) and the air exhaust section (1b) of the pump body (1), and the sealing ring (9) is located on the outside of the insert sleeve (7). The second mounting groove (1g) is also provided with two floating pressure rings (3) whose outer side walls are abutted and fixed with the elastic ring (5).

4. The anti-backflow screw vacuum pump according to claim 3, characterized in that: The inlet of the connecting pipe (12) is arranged between the second mounting groove (1g) and the air inlet (1c).

5. A screw vacuum pump with anti-backflow according to claim 1, 2, 3 or 4, characterized in that: The pump body (1) is provided with an overflow channel (10) on a side wall near the exhaust port (1d) for connecting the inner cavity of the pump body (1) and the exhaust port (1d); the inlet of the overflow channel (10) is arranged adjacent to the inner side of the floating pressure ring (3) located at one end of the exhaust port (1d); and a first overflow valve (11) is arranged in the overflow channel (10) for unidirectionally conducting the air flow in the overflow channel (10) to the exhaust port (1d).

6. A screw vacuum pump with anti-backflow according to claim 1, 2, 3 or 4, characterized in that: The pump body (1) is provided with a mounting hole (14), the compression spring (6) is arranged in the mounting hole (14), the inner end of the compression spring (6) is connected to the elastic ring (5), the outer end of the compression spring (6) is connected to a threaded plug (15), and the threaded plug (15) is threadedly connected to the hole wall of the mounting hole (14).

7. The anti-backflow screw vacuum pump according to claim 3 or 4, characterized in that: The pump body (1) has an annular positioning groove (1f), the outer end of the insert sleeve (7) has a flange portion (7a), the flange portion (7a) is embedded in the positioning groove (1f), and the inner end surface of the insert sleeve (7) is flush with the wall surface of the first installation groove (1e) or the second installation groove (1g) on ​​the side close to the exhaust port (1d).

8. The anti-backflow screw vacuum pump according to claim 1, 2, 3 or 4, characterized in that: The size of the elastic ring (5) is greater than or equal to the size of the floating pressure ring (3), and the elastic ring (5) covers and is fixed on the outer surface of the floating pressure ring (3).

9. The anti-backflow screw vacuum pump according to claim 8, characterized in that: The plurality of compression springs (6) are arranged at even intervals along the circumference of the pump body (1).

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