Vacuum Pump

Abstract

The present application provides a vacuum pump, including a pump body and an active helical rotor and a driven helical rotor meshing with each other, the active helical rotor, the driven helical rotor and the pump body together form an air suction compression chamber, the two ends of the air suction compression chamber are provided with an air suction port and an air discharge port, the pump body is provided with a guide groove connecting the closed volume after the exhaust is completed with the air suction port, the guide groove includes a first end connected to the closed volume and a second end connected to the air suction port. After the exhaust is completed, the guide groove can connect the closed volume with the air suction port in advance, so that local high pressure will not be generated, and additional power consumption and cavitation can be avoided.

Description

Technical Field

[0001] The invention relates to the technical field of vacuum pumps, and in particular to an oil-injected screw vacuum pump. Background Art

[0002] A vacuum pump is a device that uses mechanical, physical, chemical or physicochemical methods to improve, generate and maintain vacuum in a closed space. Vacuum pumps are widely used in electronics, printing and papermaking, chemical medicine, food processing and packaging, material handling and other fields. At present, the commonly used vacuum pumps on the market include screw vacuum pumps, water ring pumps, reciprocating pumps, sliding valve pumps, rotary vane pumps, Roots pumps and diffusion pumps.

[0003] The working principle of the screw vacuum pump is to use the rotation of the screw to generate vacuum. The screw vacuum pump is usually composed of two screws, one is the main screw and the other is the slave screw. The gap between the main screw and the slave screw is less than 1 mm, so a vacuum can be generated when rotating. The oil-injected screw vacuum pump can spray oil into the main engine cavity of the oil-injected screw vacuum pump through the oil-gas separation device, thereby taking away the heat generated during the compression of the gas, lubricating the screw, preventing corrosion, and ensuring the seal between the screws. The oil-injected screw vacuum pump is suitable for constantly fluctuating working conditions, has a wide adjustment range, and has good energy-saving effects.

[0004] However, after the exhaust port of the oil-injected screw vacuum pump is completely closed, there is still some volume that has not been discharged. If this part of the gas continues to be compressed, the pressure will increase locally, resulting in a pressure spike, which will generate additional power consumption. When the next suction compression cycle begins, it is suddenly connected to the exhaust port, and the local high-pressure gas is ejected. The pressure energy of this part of the gas is instantly reduced and converted into speed energy. When the pressure is lower than the saturated vapor pressure of water vapor, the water dissolved in the oil is vaporized, generating bubbles and rotating with the rotor. In the new suction process, when the internal pressure of the bubble is greater than the external suction pressure, the bubble bursts and cavitation occurs. Cavitation will impact the wall of the unit and produce a lot of noise.

[0005] Therefore, it is necessary to provide an improved vacuum pump to solve the above problems. Summary of the invention

[0006] The present application provides a vacuum pump which can connect a closed volume with a suction port in advance when exhaust is completed.

[0007] The present application discloses a vacuum pump, which comprises: a pump body and an active spiral rotor and a driven spiral rotor meshing with each other, wherein the active spiral rotor, the driven spiral rotor and the pump body together form an air suction compression chamber, wherein two ends of the air suction compression chamber are provided with an air suction port and an air exhaust port, and the pump body is provided with a guide groove connecting a closed volume after exhaust with the air suction port, wherein the guide groove comprises a first end connected with the closed volume and a second end connected with the air suction port; the guide groove and the air exhaust port are located on the same side of a center line connecting the active spiral rotor and the driven spiral rotor; the second end is close to the center line, and the first end is close to the middle of the air exhaust port.

[0008] Furthermore, when the closed volume is connected to the air extraction port, the first end and the second end are respectively located on both sides of the tooth tip of the same blade of the active spiral rotor.

[0009] Furthermore, the air inlet area of ​​the second end connected with the air suction port and the closed volume are both formed by the same pair of meshing blades and tooth grooves of the active helical rotor and the driven helical rotor.

[0010] Furthermore, during the rotation of the active helical rotor and the driven helical rotor, the guide groove is firstly communicated with the exhaust port, and then simultaneously communicated with the closed volume and the air extraction port.

[0011] Furthermore, the width of the guide groove is not less than 2 mm, and the arc angle corresponding to the starting point and the end point of the guide groove does not exceed 15°.

[0012] Furthermore, the volume of the guide groove is larger than the volume of the gas in the closed volume.

[0013] Furthermore, the guide groove is in the shape of an arc, a straight line or a right-angled broken line.

[0014] Furthermore, the exhaust port includes a first opening and a second opening, the first opening is close to the active spiral rotor, the second opening is close to the driven spiral rotor, and the first opening is closer to the center line than the second opening; an inverted triangle area is formed between the first opening and the second opening, and the first end is located in the inverted triangle area.

[0015] Furthermore, the pump body comprises an exhaust seat, and the exhaust port and the guide groove are arranged on the exhaust seat.

[0016] Compared with the prior art, the present application provides a guide groove to connect the closed volume with the exhaust port in advance after the exhaust is completed, so that no local high pressure is generated, thereby avoiding additional power consumption and cavitation.

[0017] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present specification. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the specification and, together with the description, serve to explain the principles of the specification.

[0019] Figure 1 It is a cross-sectional view of the vacuum pump of the present invention.

[0020] Figure 2 It is a side view of the vacuum pump of the present invention in the exhaust stage.

[0021] Figure 3 It is a side view of the vacuum pump of the present invention when exhaust is completed.

[0022] Figure 4 It is a side view of the vacuum pump of the present invention when the closed volume is connected to the exhaust port after exhaust is completed.

[0023] Figure 5 yes Figure 4 A partial enlarged view of .

[0024] Figure 6 It is a side view of the vacuum pump of the present invention at the stage where compression is completed and exhaust is about to begin.

[0025] Figure 7 It is a side view of the vacuum pump of the present invention at the beginning stage of new pumping.

[0026] Figure 8 It is a partial view of another embodiment of the vacuum pump of the present invention.

[0027] Fig. 9 It is a partial view of a third embodiment of the vacuum pump of the present invention.

[0028] Explanation of the accompanying drawings: pump body, 1; casing, 11; exhaust seat, 12; inner side, 121; cylindrical roller bearing, 13; angular contact ball bearing, 14; floating ring seal, 15; oil seal, 16; active spiral rotor, 2; blades, 21; driven spiral rotor, 3; tooth grooves, 31; suction compression chamber, 4; air suction port, 41; air intake area, 41a; exhaust port, 42; first opening, 42a; second opening, 42b; inverted triangle area, 42c; closed volume, 5; guide groove, 6, 6a, 6b; first end, 61; second end, 62; center line, a. DETAILED DESCRIPTION

[0029] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementations described in the following exemplary embodiments do not represent all implementations consistent with this specification. Instead, they are merely examples of devices and methods consistent with some aspects of this specification as detailed in the appended claims.

[0030] The terms used in this specification are for the purpose of describing specific embodiments only and are not intended to limit this specification. The singular forms "a", "the" and "the" used in this specification and the appended claims are also intended to include plural forms unless the context clearly indicates otherwise. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0031] It should be understood that although the terms first, second, third, etc. may be used in this specification to describe various information, this information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of this specification, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Depending on the context, the word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining".

[0032] Next, the embodiments of this specification are described in detail.

[0033] like Figure 1 As shown, the vacuum pump of the present invention comprises a pump body 1 and a driving helical rotor 2 and a driven helical rotor 3 meshing with each other. The driving helical rotor 2, the driven helical rotor 3 and the sealed pump body 1 together form a suction compression chamber 4. An air suction port 41 and an air exhaust port 42 are provided at both ends of the suction compression chamber 4. The air flow is sucked in from the air suction port 41 and discharged through the air exhaust port 42 after being compressed.

[0034] The pump body 1 includes a housing 11 and an exhaust seat 12. The driving helical rotor 2 and the driven helical rotor 3 are radially supported by cylindrical roller bearings 13, and the axial force generated by gas compression is borne by angular contact ball bearings 14. The heat generated by gas compression is taken away by the injected cooling oil, and a floating ring seal 15 is used at the shaft end for gas sealing, and a skeleton seal is used for oil seal 16.

[0035] The active spiral rotor 2 and the driven spiral rotor 3 rotate synchronously in opposite directions, and transmit the pumped gas sucked in from the suction port 41 and existing in the two spiral rotors together, moving along the axial direction of the spiral rotor from the suction end to the exhaust end until it is discharged from the pump through the exhaust port 42.

[0036] The pumping process can include three stages: suction, compression and exhaust. During the whole process, the volume and pressure changes of the gas are related to the rotation angle of the spiral rotor. The rotation angles of the spiral rotor are suction start angle, suction end compression start angle, compression end exhaust start angle, 720° exhaust end angle and the next suction start angle.

[0037] The process of spiral rotor rotating from the suction start angle to the suction end compression start angle is called suction process. The suction pressure is the intake pressure. During this process, the pressure remains unchanged but the volume increases.

[0038] The compression process is from the end of suction and the beginning of compression to the end of compression and the beginning of exhaust angle. During this process, the volume decreases and the pressure gradually rises to the designed exhaust pressure.

[0039] The exhaust process is from the exhaust start angle at the end of compression to the exhaust end angle of 720°, during which the pressure remains unchanged and the gas volume gradually decreases.

[0040] After reaching the exhaust end angle of 720°, the profiles of the two spiral rotors are completely closed to the exhaust port, and some gas is still not discharged in the closed volume formed at this time. If this part of the gas continues to be compressed during the process from the exhaust end angle of 720° to the next intake start angle, the pressure will increase locally, resulting in a pressure peak far exceeding the designed exhaust pressure and additional power consumption, and cavitation is also prone to occur.

[0041] Please refer to Figures 2 to 5 As shown, the pump body 1 of the present invention is provided with a guide groove 6 for connecting the closed volume 5 after exhaust with the air suction port 41. The guide groove 6 includes a first end 61 connected to the closed volume 5 and a second end 62 connected to the air suction port 41.

[0042] The guide groove 6 and the exhaust port 42 are both arranged on the exhaust seat 12, and can be formed by a milling cutter on the inner side 121 of the exhaust seat 12 close to the active spiral rotor 2 and the driven spiral rotor 3. The guide groove 6 and the exhaust port 42 are both located on the same side of the center line a of the active spiral rotor 2 and the driven spiral rotor 3. Figure 2 The second end 62 is close to the center line a, and the first end 61 is close to the middle of the exhaust port 42.

[0043] The exhaust port 42 includes a first opening 42a and a second opening 42b, wherein the first opening 42a is close to the active spiral rotor 2, and the second opening 42b is close to the driven spiral rotor 3. The first opening 42a is closer to the center line a than the second opening 42b. An inverted triangle area 42c is formed between the first opening 42a and the second opening 42b, and the first end 61 is located in the inverted triangle area 42c. The overall extension distance of the guide groove 6 is relatively short, and the guide groove 6 is not directly connected to the exhaust port 42.

[0044] Figure 2In the vacuum pump, the vacuum pump is in the exhaust stage, and the compressed gas is discharged from the pump through the exhaust port 42. The area where the compressed gas is located partially overlaps with the guide groove 6, so the guide groove 6 and the exhaust port 42 are connected at the same time. As the two spiral rotors rotate, they enter Figure 3 At the stage, that is, when the exhaust is finished, the exhaust port 42 will be completely closed, and the guide groove 6 will always be connected with the area where the compressed gas is located until the closed volume 5 is formed. Therefore, after the closed volume 5 is formed, the guide groove 6 is also connected with the closed volume 5.

[0045] After exhaust, the profiles of the two spiral rotors and the exhaust port 42 are completely closed. Figure 4 and Figure 5 As shown. A closed volume 5 is formed between the two spiral rotors, and some gas is still not discharged in the closed volume 5. The first end 61 of the guide groove 6 is connected to the closed volume 5. At the same time, the second end 62 of the guide groove 6 partially overlaps with the air intake area 41a formed by the two spiral rotors and connected to the air extraction port 41, and the second end 62 is connected to the air extraction port 41. Therefore, the guide groove 6 is connected to the closed volume 5 and the air extraction port 41 at the same time, so that the pressure of the closed volume 5 is connected to the intake pressure in advance.

[0046] By providing the guide groove 6, the compressed gas in the closed volume 5 is introduced into the exhaust port 41 in advance after the exhaust is completed, especially under low vacuum intake pressure, a sufficient pressure difference can be generated to promote the gas flow and avoid the occurrence of additional power consumption and cavitation. The present invention can meet the requirements of a lower ultimate vacuum of 1-3 mbarG and adapt to various working conditions with constantly changing intake pressures.

[0047] The second end 62 of the guide groove 6 and the air inlet area 41a connected to the air outlet 41 and the closed volume 5 are formed by the same pair of meshing blades 21 and tooth grooves 31 of the active helical rotor 2 and the driven helical rotor 3. The distance between the two is relatively close, and the extension distance of the guide groove 6 is relatively short. When guiding, the first end 61 and the second end 62 are respectively located on both sides of the tooth tip of the same blade 21 of the active helical rotor 2.

[0048] Please refer to Figure 6 As shown, at this time, the volume of the closed volume 5 is zero, the air extraction is about to start, and the guide groove 6 is only connected to the air extraction port 41. Figure 7 A new air extraction phase begins, at which time the guide groove 6 is not connected to the air extraction port 41 .

[0049] In an optional embodiment, the width of the guide groove 6 is not less than 2 mm, and the arc angle corresponding to the starting point and the end point of the guide groove 6 does not exceed 15°. The volume of the guide groove 6 is greater than the gas volume in the closed volume 5, and the depth of the guide groove 6 should ensure that the oil film is not squeezed. The guide groove 6 is arc-shaped.

[0050] Figures 8 to 9are two other embodiments of the vacuum pump of the present invention. Figures 2 to 7 The only difference between the embodiments is the specific shape of the guide groove 6. Figure 8 The middle guide groove 6a is a straight line. Fig. 9 The middle guide groove 6b is in the shape of a right-angled broken line.

[0051] After the exhaust is completed, some compressed gas has not been discharged and is located in the closed volume 5. A guide groove 6 is opened near the exhaust port 42 to connect the pressure of the closed volume 5 with the intake pressure in advance. This can prevent the closed volume 5 from experiencing a sudden change in gas pressure when connected to the intake vacuum chamber, thereby preventing local high pressure from occurring and causing cavitation. At the same time, it also reduces unnecessary power consumption and noise caused by cavitation.

[0052] The above is only a preferred implementation mode of the present application, and does not constitute any form of limitation to the present application. Although the present application has been disclosed as a preferred implementation mode as above, it is not used to limit the present application. Any technician familiar with this profession can make some changes or modify the technical contents disclosed above into equivalent implementation modes without departing from the scope of the technical solution of the present application. However, any simple modification, equivalent change and modification made to the above implementation modes based on the technical essence of the present application without departing from the content of the technical solution of the present application still fall within the scope of the technical solution of the present application.

Claims

1. A vacuum pump, characterized in that: include: The pump body and the active helical rotor and the driven helical rotor meshing with each other, the active helical rotor, the driven helical rotor and the pump body together form an air suction compression chamber, the two ends of the air suction compression chamber are provided with an air suction port and an air exhaust port, the pump body is provided with a guide groove connecting the closed volume after the exhaust is completed with the air suction port, the guide groove includes a first end connected with the closed volume and a second end connected with the air suction port; the guide groove and the air exhaust port are located on the same side of the center line of the active helical rotor and the driven helical rotor; the second end is close to the center line, and the first end is close to the middle of the air exhaust port; when the closed volume is connected with the air exhaust port, the first end and the second end are respectively located on the active helical rotor on both sides of the tooth tip of the same blade; the air intake area connected with the air extraction port at the second end and the closed volume are formed by the same pair of meshing blades and tooth grooves of the active spiral rotor and the driven spiral rotor; during the rotation of the active spiral rotor and the driven spiral rotor, the guide groove is first connected with the exhaust port, and then connected with the closed volume and the air extraction port at the same time; the exhaust port includes a first opening and a second opening, the first opening is close to the active spiral rotor, the second opening is close to the driven spiral rotor, and the first opening is closer to the center line than the second opening; an inverted triangle area is formed between the first opening and the second opening, and the first end is located in the inverted triangle area.

2. The vacuum pump according to claim 1, characterized in that The width of the guide groove is not less than 2 mm, and the arc angle corresponding to the starting point and the end point of the guide groove does not exceed 15°.

3. The vacuum pump according to claim 1, characterized in that The volume of the guide groove is greater than the volume of the gas in the closed volume.

4. The vacuum pump according to claim 1, characterized in that The guide groove is in the shape of an arc, a straight line or a right-angled broken line.

5. The vacuum pump according to claim 1, characterized in that The pump body comprises an exhaust seat, and the exhaust port and the guide groove are arranged on the exhaust seat.

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