A screw vacuum pump with high pumping rate

Abstract

The present invention belongs to the technical field of vacuum pumps. It solves the problem of low air pumping rate of screw vacuum pumps in the prior art. A screw vacuum pump with a high air pumping rate is provided, including a pump body and a screw, the screw having a cooling channel centered on the center line of the screw and arranged in a spiral shape, the pump body having a liquid inlet chamber and a liquid outlet chamber respectively connected to the two ends of the cooling channel, the liquid inlet chamber and the liquid outlet chamber are connected by a connecting pipe and a booster pump is arranged on the connecting pipe; two C-shaped floating pressure rings made of wear-resistant self-lubricating material and a plurality of compression springs arranged along the circumference of the pump body are also arranged on the inner wall of one end of the exhaust port of the pump body, each of the compression springs is arranged along the radial direction of the floating pressure ring and connected to the corresponding floating pressure ring, and under the action of the compression spring, the two openings of the floating pressure rings arranged opposite to each other respectively abut against the screw teeth of the two screws. Effectively improve the air pumping rate of the screw vacuum pump.

Description

Technical Field

[0001] The invention belongs to the technical field of vacuum pumps and relates to a screw vacuum pump with a high pumping rate. Background Art

[0002] At present, the screw vacuum pump is a vacuum equipment that uses a pair of screws to rotate synchronously at high speed in opposite directions inside the pump body to produce suction and exhaust effects. The vacuum performance of the screw vacuum pump is positively correlated to the rotation speed of its screw. When the screw rotates at a higher speed, the vacuum pumping speed of the screw vacuum pump is greater and the vacuum pumping effect is better. When the screw rotates at a lower speed, the vacuum pumping speed of the screw vacuum pump is lower and the vacuum performance will be greatly reduced. Therefore, the market is pursuing screw vacuum pumps with high vacuum rates.

[0003] However, the screw of the existing high-speed screw vacuum pump is prone to heat up due to friction when moving at high speed, and the screw and the pump body will deform due to thermal expansion and contraction after the temperature rises, causing the gap between the screw and the pump body to change. Specifically, when the gap between the screw and the pump body becomes larger, the gas in the pump body is easy to leak, resulting in a decrease in the air extraction efficiency. When the gap between the screw and the pump body becomes smaller, the friction and wear of the screw and the pump body will increase, thereby accelerating the wear of the screw. After the screw is worn, on the one hand, the gap between the screw and the pump body increases, and it will flow back from the gap between the pump body and the screw. This part of the reflux gas will produce a reverse thrust on the screw. On the other hand, 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 air extraction rate 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 a high pumping rate. The technical problem to be solved by the present invention is how to effectively improve the pumping rate 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 with a high suction rate comprises a pump body and two mutually meshing screws rotatably arranged in the pump body, characterized in that the screw is provided with a cooling channel centered on the center line of the screw and arranged in a spiral shape, the two ends of the cooling channel respectively pass through the two end faces of the screw, the pump body is provided with a liquid inlet chamber and a liquid outlet chamber respectively connected to the two ends of the cooling channel, the liquid inlet chamber and the liquid outlet chamber are connected by a connecting pipe and a booster pump is arranged on the connecting pipe; two floating pressure rings made of wear-resistant self-lubricating material and in a C shape and a plurality of compression springs arranged along the circumference of the pump body are also arranged on the inner wall of one end of the exhaust port of the pump body, a floating gap is provided between the two ends of the two floating pressure rings located on the same side, each of the compression springs is arranged along the radial direction of the floating pressure ring and connected to the corresponding floating pressure ring, and under the action of the compression spring, the two floating pressure rings with openings arranged opposite to each other respectively abut against the thread teeth of the two screws.

[0007] The screw vacuum pump with high pumping rate, on the one hand, provides a cooling channel on the screw that is spirally connected to the liquid inlet chamber and the liquid outlet chamber of the pump body. At the same time, the liquid inlet chamber and the liquid outlet chamber are connected by a connecting pipe and a booster pump is provided on the connecting pipe, so that the coolant circulates between the connecting pipe and the cooling channel, thereby achieving direct cooling of the screw when the screw vacuum pump is working, so that the temperature of the screw and the pump body is maintained within a reasonable range, and the deformation of the screw and the pump body due to the increase in temperature, which causes the gap between the screw and the pump body to change, thereby causing a decrease in the pumping rate; on the other hand, two C-shaped floating pressure rings made of wear-resistant self-lubricating material are provided on the pump body And a number of compression springs arranged along the circumference of the pump body, so that under the action of the compression springs, the two openings are relatively arranged. The floating pressure rings respectively abut against the thread teeth of the two screws, thereby effectively preventing the gas in 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, and avoiding the reverse flow of gas to produce a reverse thrust on the screw. Obviously, relying solely on direct cooling of the screw cannot change the original gap between the screw and the pump body, and part of the reverse flow of gas will still produce a reverse thrust on the screw, causing the pumping rate of the screw vacuum pump to decrease. Therefore, in the present high pumping rate screw vacuum pump, the "cooling channel for direct cooling of the screw" and the "floating pressure ring for preventing backflow" are interrelated, and the two are indispensable to form an overall technical solution to effectively improve the pumping rate of the screw vacuum pump.

[0008] In the above-mentioned high-pumping-rate screw vacuum pump, the screw includes a shaft and a spiral rotor sleeved on the shaft, the shaft and the rotor are fixed by welding, and L-shaped flow channels are provided at both ends of the shaft, which are respectively connected to the liquid inlet chamber and the liquid outlet chamber, and the two L-shaped flow channels are respectively connected to the cooling channel located inside the rotor. The processing and manufacturing of the cooling channel and the L-shaped flow channel are convenient, and at the same time, by welding the rotor to the shaft, the coolant is prevented from leaking from the connection between the two, so that the direct cooling of the screw is better achieved when the screw vacuum pump is working.

[0009] In the above-mentioned screw vacuum pump with a high pumping rate, the screw is integrally formed, the cooling channel is recessed on the outer wall of the screw thread, and a sealing plate for closing the opening is welded at the opening of the cooling channel. L-shaped flow channels are respectively connected to the liquid inlet chamber and the liquid outlet chamber at both ends of the screw, and the two L-shaped flow channels are also respectively connected to the cooling channel. By recessing the cooling channel on the outer wall of the screw thread, the processing and manufacturing of the spiral cooling channel can be facilitated. At the same time, by welding a sealing plate at the opening of the cooling channel, leakage of coolant in the cooling channel can be avoided, thereby better realizing direct cooling of the screw when the screw vacuum pump is working.

[0010] In the above-mentioned screw vacuum pump with a high suction rate, a cooling coil is arranged in the cooling channel, and the two ends of the cooling coil are respectively connected with cylindrical coil joints which are connected with the interior of the cooling coil, and the two coil joints are respectively clamped on the inner walls at the two ends of the cooling channel, and the coil joints are sleeved with sealing rings for forming abutment seal with the inner wall of the cooling channel, and the two ends of the screw are also provided with L-shaped flow channels which are respectively connected with the liquid inlet chamber and the liquid outlet chamber, and the two L-shaped flow channels are also respectively connected with the two coil joints. By setting a coil joint, the two ends of the cooling coil can be fixed to avoid the cooling coil from moving at will. At the same time, by sleeved with a sealing ring on the coil joint, the sealing ring forms a seal between the coil joint and the cooling channel. The coolant passes through the liquid inlet chamber, the L-shaped flow channel connected to the liquid inlet chamber, the inside of the coil joint, the inside of the cooling coil, the inside of another coil joint, the L-shaped flow channel connected to the liquid outlet chamber, the liquid outlet chamber, the connecting pipe and the booster pump in sequence. Under the action of the booster pump, the coolant is circulated in the above circuit, so that the direct cooling of the screw can be better achieved when the screw vacuum pump is working.

[0011] In the above-mentioned high-pumping-rate screw vacuum pump, spiral steps are provided on both inner walls of the open opening of the cooling channel, and the sealing plate is spiral and welded to the steps. The step can facilitate the welding and fixing of the sealing plate, and make the connection tighter, thereby avoiding shaking and leakage.

[0012] In the above-mentioned high-pumping-rate screw vacuum pump, an elastic ring capable of elastic deformation is also fixed against the outer wall 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 threads of the two screws. After absorbing the pressure of several compression springs, the elastic ring can convert the "point-to-point" pressure 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 against the threads of the corresponding screws, thereby effectively preventing part of the gas in the pump body from flowing back from the gap between the pump body and the screw under high pressure.

[0013] In the above-mentioned high-pumping-rate screw vacuum pump, an annular mounting groove is provided on the inner wall of the pump body, the floating pressure ring is arranged in the mounting groove, and an annular insert is axially inserted at the exhaust port end of the pump body, the inner side surface of the insert 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 insert. By providing the insert, the disassembly and assembly of the floating pressure ring can be facilitated, and by arranging the inner side surface of the insert flush with the inner wall surface of the pump body, the movement interference between the insert and the screw in the pump body is avoided, 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 ensuring the working stability of the screw vacuum pump while solving the backflow problem of the screw vacuum pump.

[0014] In the above-mentioned high-pumping-rate 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 screw plug, and the screw 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 screw 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 screw 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.

[0015] Compared with the prior art, the advantages of the screw vacuum pump with a high pumping rate are as follows: on the one hand, a cooling channel is provided on the screw which is in a spiral shape and connected to the liquid inlet chamber and the liquid outlet chamber of the pump body, and at the same time, the liquid inlet chamber and the liquid outlet chamber are connected by a connecting pipe and a booster pump is provided on the connecting pipe, thereby realizing direct cooling of the screw when the screw vacuum pump is working, so that the temperature of the screw is kept within a reasonable range; on the other hand, two floating pressure rings made of wear-resistant self-lubricating material and in a C shape and a plurality of compression springs arranged along the circumference of the pump body are provided on the pump body, so that under the action of the compression springs, the two openings of the floating pressure rings arranged opposite to each other respectively abut against the threads 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. The two are indispensable and form an overall technical solution to effectively improve the pumping rate of the screw vacuum pump. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the structure of the screw vacuum pump with high pumping rate in the first embodiment.

[0017] Figure 2 yes Figure 1 Cross-sectional view at AA after removing the screw and connecting tube.

[0018] Figure 3 yes Figure 2 A partial enlarged view of point A in the middle.

[0019] Figure 4 It is a cross-sectional view of the screw vacuum pump with high pumping rate in the second embodiment.

[0020] Figure 5 yes Figure 4 A partial enlarged view of point B in the middle.

[0021] Figure 6 It is a cross-sectional view of the screw of the screw vacuum pump with high pumping rate in Example 3.

[0022] Figure 7 It is a cross-sectional view of the screw of the screw vacuum pump with high pumping rate in the fourth embodiment.

[0023] Figure 8 yes Figure 7 A partial enlarged view of point C in the middle.

[0024] In the figure, 1, pump body; 1a, liquid inlet chamber; 1b, liquid outlet chamber; 1c, mounting groove; 1d, mounting hole; 2, screw; 2a, cooling channel; 2b, shaft; 2c, rotor; 2d, L-type flow channel; 3, connecting pipe; 4, booster pump; 5, floating pressure ring; 6, compression spring; 7, sealing plate; 8, cooling coil; 9, coil joint; 10, sealing ring; 11, step portion; 12, elastic ring; 13, sleeve; 14, sliding spacing; 15, screw plug; 16, floating clearance. DETAILED DESCRIPTION

[0025] 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.

[0026] Embodiment 1

[0027] A screw vacuum pump with high pumping speed, refer to Figure 1-3 , comprising a pump body 1 and two mutually meshing screws 2 rotatably arranged in the pump body 1, the screw 2 having a cooling channel 2a centered on the center line of the screw 2 and arranged in a spiral shape, the pump body 1 having a liquid inlet chamber 1a and a liquid outlet chamber 1b respectively connected to the two ends of the cooling channel 2a, the liquid inlet chamber 1a and the liquid outlet chamber 1b being connected by a connecting pipe 3 and a booster pump 4 being arranged on the connecting pipe 3; two floating pressure rings 5 ​​made of wear-resistant self-lubricating material and in a C shape and a plurality of compression springs 6 arranged along the circumference of the pump body 1 are also arranged on the inner wall of one end of the exhaust port of the pump body 1, a floating gap 16 is provided between the two ends of the two floating pressure rings 5 ​​located on the same side, each of the compression springs 6 is arranged along the radial direction of the floating pressure ring 5 and connected to the corresponding floating pressure ring 5, and under the action of the compression spring 6, the floating pressure rings 5 ​​with two openings arranged opposite to each other respectively abut against the thread teeth of the two screws 2.

[0028] Specifically, refer to Figure 1-3 An elastic ring 12 capable of elastic deformation is also fixed on the outer wall of the floating pressure ring 5, and the inner end of each compression spring 6 is connected to the elastic ring 12 on the corresponding floating pressure ring 5 so that the two floating pressure rings 5 ​​are respectively against the thread of the two screws 2.

[0029] More specifically, refer to Figure 1-3 An annular mounting groove 1c is provided on the inner wall of the pump body 1, and the floating pressure ring 5 is arranged in the mounting groove 1c. An annular insert 13 is axially inserted at the exhaust port end of the pump body 1. The inner side surface of the insert 13 is flush with the inner wall surface of the pump body 1, and a sliding spacing 14 is provided between the floating pressure ring 5 and the insert 13.

[0030] More specifically, refer to Figure 1-3 The pump body 1 is provided with a mounting hole 1d, the compression spring 6 is arranged in the mounting hole 1d, the inner end of the compression spring 6 is connected to the elastic ring 12, the outer end of the compression spring 6 is connected to the thread plug 15, and the thread plug 15 is threadedly connected to the hole wall of the mounting hole 1d.

[0031] In this embodiment, preferably, a plurality of the compression springs 6 are evenly spaced along the circumference of the pump body 1; preferably, the size of the elastic ring 12 is greater than or equal to the size of the floating pressure ring 5, and the elastic ring 12 covers and is fixed to the outer surface of the floating pressure ring 5; preferably, the pump body 1 includes an intake section and an exhaust section connected front and rear, and the pump body 1 is also provided with an annular mounting groove 1c on one side of the connection between the intake section and the exhaust section and the sleeve 13 is axially inserted therein, and a sealing ring is also provided at the connection between the intake section and the exhaust section of the pump body 1, and the sealing ring is located on the outside of the sleeve 13, and the mounting groove 1c is also provided with two floating pressure rings 5 ​​with the elastic ring 12 fixed against the outer wall.

[0032] On the one hand, the screw vacuum pump with high pumping rate is provided with a cooling channel 2a which is spirally shaped and connected with the liquid inlet chamber 1a and the liquid outlet chamber 1b of the pump body 1 on the screw 2, and at the same time, the liquid inlet chamber 1a and the liquid outlet chamber 1b are connected by a connecting pipe 3 and a booster pump 4 is provided on the connecting pipe 3. When the screw vacuum pump is working, the coolant passes through the liquid inlet chamber 1a, the L-shaped flow channel 2d connected with the liquid inlet chamber 1a, the cooling channel 2a, the L-shaped flow channel 2d connected with the liquid outlet chamber 1b, the liquid outlet chamber 1b, the connecting pipe 3 and the booster pump 4 in sequence, and the coolant circulates in the above-mentioned circuit under the action of the booster pump 4, so that the screw 2 is directly cooled when the screw vacuum pump is working, so that the temperature of the screw 2 is kept within a reasonable range, and the deformation of the screw 2 and the pump body 1 due to the increase in temperature is avoided, which causes the gap between the screw and the pump body to change, thereby causing a decrease in the pumping rate;

[0033] On the other hand, by arranging two C-shaped floating pressure rings 5 ​​made of wear-resistant self-lubricating material and a plurality of compression springs 6 arranged along the circumference of the pump body 1 on the pump body 1, the floating pressure rings 5 ​​with two openings arranged opposite to each other respectively abut against the screw teeth of the two screw rods 2 under the action of the compression springs 6. Furthermore, after absorbing the pressure of the plurality of compression springs 6, the elastic ring 12 can convert the "point-to-point" pressure into "face-to-face" pressure, that is, the elastic ring 12 of the anti-backflow screw vacuum pump can uniformly apply the pressure of the compression springs 6 to the floating pressure ring 5, so that the two floating pressure rings 5 ​​made of wear-resistant self-lubricating material can respectively be more closely attached to the opposite sides. The thread of the screw 2 should be on the thread of the screw 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, thereby effectively preventing part of the gas near the exhaust port 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, and avoiding the refluxed gas from generating a reverse thrust on the screw 2. Obviously, simply relying on direct cooling of the screw 2 cannot change the original gap between the screw 2 and the pump body 1, and part of the refluxed gas will still generate a reverse thrust on the screw 2, causing the pumping rate of the screw vacuum pump to decrease. Therefore, in the present screw vacuum pump with a high pumping rate, the "cooling channel 2a for direct cooling of the screw 2" and the "floating pressure ring 5 for preventing reflux" are interrelated, and the two are indispensable to form an overall technical solution to effectively improve the pumping rate of the screw vacuum pump.

[0034] Embodiment 2

[0035] The structure and principle of this embodiment are basically the same as those of the first embodiment, except that: Figure 4 and Figure 5 The screw 2 includes a shaft 2b and a spiral rotor 2c sleeved on the shaft 2b. The shaft 2b and the rotor 2c are fixed by welding. L-shaped flow channels 2d respectively connected to the liquid inlet chamber 1a and the liquid outlet chamber 1b are opened inside the two ends of the shaft 2b. The two L-shaped flow channels 2d are also respectively connected to the cooling channel 2a located inside the rotor 2c.

[0036] Embodiment 3

[0037] The structure and principle of this embodiment are basically the same as those of the first embodiment, except that: Figure 6 The screw 2 is integrally formed, the cooling channel 2a is recessed on the outer wall of the screw thread 2, and a sealing plate 7 for closing the open opening is welded at the open opening of the cooling channel 2a. L-shaped flow channels 2d respectively connected to the liquid inlet chamber 1a and the liquid outlet chamber 1b are also provided at both ends of the screw 2, and the two L-shaped flow channels 2d are also respectively connected to the cooling channel 2a.

[0038] Embodiment 4

[0039] The structure and principle of this embodiment are basically the same as those of the third embodiment, except that: Figure 7 and Figure 8 A cooling coil 8 is arranged in the cooling channel 2a, and both ends of the cooling coil 8 are respectively connected with a cylindrical coil joint 9 which is connected to the interior of the cooling coil 8, and the two coil joints 9 are respectively clamped on the inner walls at both ends of the cooling channel 2a, and the coil joints 9 are sleeved with a sealing ring 10 for forming abutment and sealing with the inner wall of the cooling channel 2a, and L-shaped flow channels 2d respectively connected to the liquid inlet chamber 1a and the liquid outlet chamber 1b are also opened at both ends of the screw 2, and the two L-shaped flow channels 2d are also respectively connected to the two coil joints 9; further, spiral step portions 11 are provided on the inner walls on both sides of the open mouth of the cooling channel 2a, and the sealing plate 7 is spiral and welded and fixed on the step portion 11.

[0040] 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 with a high pumping rate, comprising a pump body (1) and two mutually meshing screws (2) rotatably arranged in the pump body (1), characterized in that: The screw (2) has a cooling channel (2a) arranged in a spiral shape with the center line of the screw (2) as the center, and the pump body (1) has a liquid inlet chamber (1a) and a liquid outlet chamber (1b) respectively connected to the two ends of the cooling channel (2a), the liquid inlet chamber (1a) and the liquid outlet chamber (1b) are connected by a connecting pipe (3) and a booster pump (4) is arranged on the connecting pipe (3); the inner wall of one end of the exhaust port of the pump body (1) is also provided with two wear-resistant self-lubricating A floating pressure ring (5) made of a material and in a C shape and a plurality of compression springs (6) arranged along the circumference of the pump body (1), a floating gap (16) is provided between the two ends of the two floating pressure rings (5) located on the same side, each of the compression springs (6) is arranged along the radial direction of the floating pressure ring (5) and is connected to the corresponding floating pressure ring (5), and under the action of the compression springs (6), the two floating pressure rings (5) with openings arranged opposite to each other respectively abut against the threads of the two screws (2).

2. A screw vacuum pump with a high pumping rate according to claim 1, characterized in that: The screw (2) comprises a shaft (2b) and a helical rotor (2c) sleeved on the shaft (2b); the shaft (2b) and the rotor (2c) are fixed by welding; L-shaped flow channels (2d) respectively connected to a liquid inlet chamber (1a) and a liquid outlet chamber (1b) are provided at both ends of the shaft (2b); the two L-shaped flow channels (2d) are respectively connected to a cooling channel (2a) located inside the rotor (2c).

3. A screw vacuum pump with a high pumping rate according to claim 1, characterized in that: The screw (2) is integrally formed, the cooling channel (2a) is recessed on the outer wall of the screw thread (2), and a sealing plate (7) for closing the open opening is welded at the open opening of the cooling channel (2a). L-shaped flow channels (2d) respectively connected to the liquid inlet chamber (1a) and the liquid outlet chamber (1b) are also provided at both ends of the screw (2), and the two L-shaped flow channels (2d) are also respectively connected to the cooling channel (2a).

4. A screw vacuum pump with a high pumping rate according to claim 3, characterized in that: A cooling coil (8) is arranged in the cooling channel (2a), and the two ends of the cooling coil (8) are respectively connected to cylindrical coil joints (9) which are connected to the interior of the cooling coil (8), and the two coil joints (9) are respectively clamped on the inner walls of the two ends of the cooling channel (2a), and the coil joints (9) are sleeved with sealing rings (10) for forming abutment and sealing with the inner wall of the cooling channel (2a), and the two ends of the screw (2) are also provided with L-shaped flow channels (2d) respectively connected to the liquid inlet chamber (1a) and the liquid outlet chamber (1b), and the two L-shaped flow channels (2d) are also respectively connected to the two coil joints (9).

5. A screw vacuum pump with a high pumping rate according to claim 3, characterized in that: Spiral step portions (11) are provided on both inner walls of the open opening of the cooling channel (2a), and the sealing plate (7) is spiral and is welded and fixed on the step portions (11).

6. A screw vacuum pump with a high pumping rate according to any one of claims 1 to 5, characterized in that: An elastic ring (12) capable of elastic deformation is also fixedly attached to the outer wall of the floating pressure ring (5), and the inner end of each compression spring (6) is connected to the elastic ring (12) on the corresponding floating pressure ring (5) so that the two floating pressure rings (5) respectively abut against the threads of the two screw rods (2).

7. A screw vacuum pump with a high pumping rate according to claim 6, characterized in that: An annular mounting groove (1c) is provided on the inner wall of the pump body (1), and the floating pressure ring (5) is arranged in the mounting groove (1c). An annular insert (13) is axially inserted into the pump body (1) at the exhaust port end, and the inner side surface of the insert (13) is flush with the inner wall surface of the pump body (1), and a sliding spacing (14) is provided between the floating pressure ring (5) and the insert (13).

8. A screw vacuum pump with a high pumping rate according to claim 6, characterized in that: The pump body (1) is provided with a mounting hole (1d), the compression spring (6) is arranged in the mounting hole (1d), the inner end of the compression spring (6) is connected to the elastic ring (12), 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 (1d).

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