A pump body and a vacuum pump

Abstract

This invention discloses a pump body and a vacuum pump, characterized by: a pump casing and an end cover; the pump casing having a chamber extending through both ends axially, the chamber accommodating a portion of the rotor; a main air inlet communicating with the chamber on the front outer wall of the pump casing; the end cover located at the rear end of the pump casing, closing the rear end of the chamber; a rear rotor cavity facing the chamber on the front surface of the end cover, accommodating the rotor exposed at the rear end of the chamber; and an exhaust port communicating with the rear rotor cavity on the outer wall of the end cover. This invention improves assembly convenience and efficiency, ensures assembly accuracy, and facilitates maintenance.

Description

Technical Field

[0001] This invention relates to a vacuum pump, and more particularly to a pump body and a vacuum pump. Background Technology

[0002] Vacuum pumps are classified in many ways, and different vacuum pumps are used in different industries. For example, Roots vacuum pumps and screw vacuum pumps can be used individually or in combination. For instance, patent application number "202421278655.0", entitled "A Two-Shaft Mixing Pump", describes a three-stage mixing pump, or a traditional vacuum pump. In this pump, the rotor and rotor cavity inside the pump body have an equal-length structure (the length of the rotor and the length of the rotor cavity are the same; however, the length of the rotor cavity is slightly longer than the rotor length to allow for assembly and rotation clearance and prevent pump jamming). However, this structure has the following drawbacks: 1. Once the rotor is installed in the pump body, the meshing clearance of the two or three or more rotors and the clearance between the rotor and the end face of the rotor cavity can only be determined through the air inlet (suction port) and exhaust port of the vacuum pump, which affects the assembly efficiency and assembly accuracy; at the same time, it is also very inconvenient to check the second time. 2. The temperature at the exhaust port of the vacuum pump is the highest in the entire vacuum pump. High temperature will cause the metal to expand more, exceeding the reserved gap, which can easily cause the pump to jam. Therefore, the reserved gap between the rotor and the pump body at the exhaust port needs to be larger. Since the length of the rotor is the same as the length of the rotor cavity, the processing space and adjustment space are more troublesome. In addition, it is necessary to maintain, clean, repair and polish this area frequently. It is necessary to disassemble the entire vacuum pump or disassemble the last vacuum pump. After subsequent installation, the reassembly process needs to be repeated, which is very inconvenient. Summary of the Invention

[0003] The purpose of this invention is to provide a pump body and a vacuum pump, which improves the ease of assembly and assembly accuracy by using this structure.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is: a pump body, comprising: The pump casing has a chamber extending through both ends in the axial direction. The chamber is used to accommodate part of the rotor. The front outer wall of the pump casing has a main air inlet that communicates with the chamber. A first end cap is disposed at the front end of the pump housing and closes the front end of the chamber; An end cover is provided at the rear end of the pump housing and closes the rear end of the chamber; a rear rotor cavity is provided on the front end face of the end cover facing the chamber, and the rear rotor cavity accommodates the rotor exposed at the rear end of the chamber; an exhaust port communicating with the rear rotor cavity is provided on the outer wall of the end cover.

[0005] In the above technical solution, at least one partition is detachably installed in the chamber, and the partition divides the chamber into multiple rotor chambers from front to back. The last rotor chamber is used to accommodate the rearmost sub-rotor portion of the rotor, and the rear rotor chamber is used to accommodate the sub-rotor exposed at the rear end of the rearmost rotor chamber.

[0006] In the above technical solution, the size of the multiple rotor cavities decreases sequentially from front to back, and the size of the rotor cavity located at the front end of the partition is larger than the size of the rotor cavity located at the rear end of the partition.

[0007] In the above technical solution, the size of the rotor cavity at the rearmost end is less than or equal to the size of the rear rotor cavity; And / or, the length of the rear rotor cavity is greater than or equal to the length of the rear rotor cavity.

[0008] In the above technical solution, each of the partitions is provided with at least two shaft holes in the middle, the shaft holes are used to accommodate the rotating shaft in the rotor, and the shaft holes connect two adjacent rotor cavities.

[0009] In the above technical solution, an annular groove is provided on the inner surface of the shaft hole, and a shaft sealing plate is detachably installed in the annular groove, with the inner surface of the shaft sealing plate exposed in the shaft hole.

[0010] In the above technical solution, the pump casing is provided with multiple connecting air passages that connect adjacent rotor cavities.

[0011] In the above technical solution, the inlet of the connecting air passage is connected to the bottom of the front rotor cavity, and the outlet of the connecting air passage is connected to the top, side or front of the adjacent rear rotor cavity.

[0012] In the above technical solution, the bottom of the last partition plate is provided with a notch, which connects the bottom of the last rotor cavity and the bottom of the adjacent front rotor cavity.

[0013] In the above technical solution, the rotor cavity is a Roots rotor cavity and / or a screw rotor cavity.

[0014] In the above technical solution, the last rotor cavity and the rear rotor cavity are screw rotor cavities; A cavity is provided between the rotor cavity at the rear end and the partition at the rear end, and the outlet of the connecting air passage at the rear end is connected to the cavity.

[0015] In the above technical solution, all the rotor cavities and the rear rotor cavity are screw rotor cavities; a cavity is also provided between each rotor cavity and the partition plate at the front end of the corresponding rotor cavity; The inlet of each of the connecting air passages is connected to the rear bottom or rear end face of the adjacent front rotor cavity, and the outlet of each of the connecting air passages is connected to the adjacent rear cavity.

[0016] In the above technical solution, the main air inlet is connected to the top of the rotor cavity at the foremost end; A bypass channel is also provided, which is located inside and / or outside the pump casing; The inlet of the bypass channel is connected to the bottom of the frontmost rotor cavity, and the outlet of the bypass channel is connected to the outer wall of the pump casing or the outer wall of the end cover.

[0017] In the above technical solution, a one-way pressure relief valve is provided in the middle of the bypass channel.

[0018] In the above technical solution, an end pressure relief channel is provided on the front end surface of the end cover. The end pressure relief channel is located on the side or periphery of the rear rotor cavity, and the inlet of the end pressure relief channel is connected to the outlet of the bypass channel.

[0019] In the above technical solution, the outlet of the end pressure relief channel is connected to the outer wall of the end cap.

[0020] In the above technical solution, the top of the end cap is provided with a pressure relief chamber, one end of which is connected to the outlet of the end pressure relief channel, and the other end of which is connected to the outer wall of the end cap.

[0021] In the above technical solution, the pressure relief chamber is connected to the end pressure relief channel via at least one connecting hole, and the pressure relief chamber is connected to the outer wall of the end cover via a pressure relief bypass channel; A pressure relief device is detachably installed in the pressure relief chamber. The pressure relief device includes a pressure relief shell and pressure relief balls. The number of pressure relief balls matches the number of connection holes. The pressure relief shell has a connection cavity. The bottom of the pressure relief shell has a first hole and a second hole communicating with the connection cavity. The first hole is positioned opposite the pressure relief bypass channel. Each second hole is positioned opposite a connection hole. The first hole connects the connection cavity and the pressure relief bypass channel, and the second hole connects the corresponding connection hole and the connection cavity. The pressure relief balls are housed in the connection cavity, and each pressure relief ball is positioned opposite a second hole. Under gravity, the bottom outer surface of the pressure relief ball abuts against the top inner surface of the second hole, closing the second hole.

[0022] In the above technical solution, when the gas pressure at the bottom of the pressure relief ball exceeds a preset value, the pressure relief ball moves upward and opens the top of the second hole, so that the connecting hole communicates with the pressure relief bypass channel through the second hole, the connecting cavity, and the first hole.

[0023] In the above technical solution, the top of the connecting cavity is connected to the top of the pressure relief housing, and the top of the pressure relief housing is detachably equipped with a pressure relief cover plate to close the top of the connecting cavity; And / or, the pressure relief housing and the pressure relief cover are made of stainless steel.

[0024] In the above technical solution, a bearing cavity is provided on the rear end face of the end cover, and the bearing cavity is connected to the rear rotor cavity through the shaft hole.

[0025] In the above technical solution, the end cover outside the bearing cavity is provided with a bearing cooling water channel, and the outer wall of the end cover is provided with a bearing cooling water inlet and a bearing cooling water outlet that communicate with the bearing cooling water channel.

[0026] In the above technical solution, a jacketed water cavity is also provided inside the pump casing outside the rotor cavity at the last end; And / or, the outer wall of the pump casing is provided with an inlet and an outlet that communicate with the jacketed water chamber.

[0027] In the above technical solution, the pump casing is an integral structure.

[0028] The present invention also provides a vacuum pump, which further includes the pump body described above.

[0029] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art: 1. In this invention, the pump body is composed of a pump casing and a second end cover. The pump casing is used to accommodate most of the rotor, while the end cover is used to accommodate the rotor exposed at the rear end of the chamber. Compared with the previous structure in which the entire rotor is set in a rotor cavity, this effectively reduces the difficulty of assembly, maintenance and disassembly, improves the convenience of assembly, disassembly and maintenance, and also improves the assembly accuracy. 2. In this invention, only the pump casing and end cover are used to house the rotor. The chamber inside the pump casing and the rear rotor chamber inside the end cover constitute the rotor chamber that houses all the rotors. The pump casing and end cover only need a small sealing surface to achieve sealing. Compared with the previous structure, there are fewer sealing points and the sealing surface is smaller, reducing the number of sealing connections and effectively reducing the risk of leakage. 3. In this invention, only a longer pump casing and a shorter end cover are needed to accommodate the rotor. Compared with the previous multi-section pump casing structure, this can improve the machining accuracy of the pump body at the exhaust end. 4. In this invention, the dimensions of multiple rotor cavities decrease progressively from front to back, which facilitates the assembly of the multi-stage vacuum pump with the pump housing; 5. In this invention, the rearmost rotor portion is exposed outside the pump casing. The rear rotor cavity of the end cover accommodates the exposed rotor, which facilitates the measurement of the gap (outer circle, meshing, and end face) between the rotor and the inner wall of the cavity. It also facilitates the adjustment of the gap by means of gears and shims, and facilitates the assembly and gap adjustment of the rotor and the pump casing at the exhaust end. It also facilitates subsequent secondary inspection and maintenance. 6. In this invention, the rearmost rotor portion is exposed outside the pump casing. The rear rotor cavity of the end cover accommodates the exposed rotor, which facilitates maintenance, cleaning, repair, and polishing of the end cover and rotor at the exhaust end. Furthermore, during maintenance, only the end cover needs to be removed, improving the convenience of maintenance, cleaning, and repair and reducing the difficulty of maintenance, cleaning, and repair. 7. The shaft sealing plate provided on the shaft hole in this invention can reduce friction and noise between the shaft and the partition during shaft runout, extend service life, reduce maintenance rate, and ensure vacuuming effect; 8. The bypass channel and one-way pressure relief valve in this invention can effectively prevent pressure buildup inside the two rotor chambers at the front end, reduce the temperature of the front pump casing and the front rotor, extend service life, and reduce maintenance rate. 9. The present invention also includes a jacketed water cavity, which facilitates cooling of the pump casing at the rotor cavity at the rear end where the temperature is highest, thereby reducing the maintenance rate and extending the service life. 10. The present invention also includes a bearing cooling water channel to cool the bearing, extend the bearing's service life, and reduce the maintenance rate; 11. In this invention, a cavity is also provided between the rotor cavity at the last end and the partition plate, so that the gas fed into the rotor cavity at the last end can be pre-distributed evenly in the cavity and easily sucked away by the rotor at the last end, reducing the noise during the vacuuming process, reducing the impact of airflow on the rotor at the last end, extending the service life and reducing the maintenance rate. 12. The present invention also includes a pressure relief device inside the end cap, which can release the pressure of the excessively high-pressure gas sucked into the front rotor, eliminating the need for additional compression of this gas, reducing energy consumption, and also reducing temperature. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the pump body in Embodiment 1 of the present invention (with the end cover and pump casing separated). Figure 2 This is a cross-sectional view of the pump body in Embodiment 1 of the present invention (the partition is not shown when the end cover and pump casing are separated). Figure 3 This is a schematic diagram of the pump casing structure in Embodiment 1 of the present invention (cross-sectional view at the first stage rotor cavity). Figure 4 This is a cross-sectional view of the pump casing from one perspective in Embodiment 1 of the present invention; Figure 5 yes Figure 4 A schematic diagram of the three-dimensional structure; Figure 6 yes Figure 2 A three-dimensional structural diagram of the pump casing; Figure 7 This is a schematic diagram of the pump casing structure in Embodiment 1 of the present invention (in cross-sectional view at the secondary rotor cavity). Figure 8 This is a cross-sectional view (in three-dimensional state) of the end cap in Embodiment 1 of the present invention. Figure 9 This is a cross-sectional view of the end cap in Embodiment 1 of the present invention; Figure 10 This is a schematic diagram of the internal structure of the pressure relief shell in Embodiment 1 of the present invention.

[0031] The components include: 1. Pump casing; 11. Chamber; 12. Main air inlet; 13. Baffle plate; 15. Bypass channel; 16. One-way pressure relief valve; 17. Jacketed water chamber; 18. Inspection port. 110. Rotor cavity; 111. Primary rotor cavity; 112. Secondary rotor cavity; 113. Tertiary rotor cavity; 114. Cavity; 130. Shaft hole; 131. Annular groove; 132. Shaft seal; 133. Notch; 141. Primary connecting air passage; 142. Secondary connecting air passage; 2. End cap; 21. Rear rotor cavity; 22. Exhaust port; 23. End pressure relief channel; 24. Pressure relief chamber; 25. Pressure relief device; 26. Connecting hole; 27. Pressure relief bypass channel; 28. Bearing cavity; 29. ​​Shaft hole; 201. Lip seal cavity; 202. Bearing cooling water channel; 251. Pressure relief housing; 252. Pressure relief ball; 253. Connecting cavity; 254. First hole; 255. Second hole; 256. Pressure relief cover plate. Detailed Implementation

[0032] The present invention will be further described below with reference to the accompanying drawings and embodiments: Example 1: See Figure 1-10 As shown, a pump body includes a pump casing 1 and an end cover 2; The pump casing 1 is provided with a chamber 11 that extends through both ends axially. The chamber 11 is used to accommodate part of the rotor. The front outer wall of the pump casing 1 is provided with a main air inlet 12 that communicates with the chamber 11. The end cap 2 is disposed at the rear end of the pump housing 1 and closes the rear end of the chamber 11; the front end surface of the end cap 2 is provided with a rear rotor cavity 21 facing the chamber 11, and the rear rotor cavity 21 accommodates the rotor exposed at the rear end of the chamber 11; the outer wall of the end cap 2 is provided with an exhaust port 22 communicating with the rear rotor cavity 21. Preferably, the exhaust port is connected to the bottom of the rear end of the rear rotor cavity.

[0033] This invention also provides a vacuum pump, further comprising the aforementioned pump body. The vacuum pump also includes a first end cover (not shown in the figure), a drive mechanism, and two sets of meshing rotors. Most of the two sets of meshing rotors are housed within the chamber, with a portion of the rotors protruding outside the chamber and inserted into the rear rotor cavity of the end cover. The first end cover is located at the front end of the pump casing, sealing the front end of the chamber. Two bearings are installed in both the first end cover and the end cover to provide rotational support for both ends of the two sets of rotors. One end of each set of rotors is connected via a transmission mechanism (e.g., a gear is installed at the front end of each set of rotors, and the two gears mesh). The drive mechanism drives one set of rotors to rotate, and the transmission mechanism drives both sets of rotors to rotate synchronously in opposite directions. During operation, as the two sets of rotors rotate, they draw in gas from the main inlet and discharge it from the exhaust port, achieving the vacuuming action.

[0034] The end cover is located at the exhaust end of the entire vacuum pump, where the temperature is highest. High temperature will cause the metal at this point to expand, which may exceed the gap reserved between the rotor and the rear rotor cavity, leading to pump jamming. Therefore, the rear rotor cavity is set on the end cover, and the exhaust port is set on the end cover. That is, the rear rotor cavity can be machined independently, which facilitates the high-precision machining of the rear rotor cavity and the reservation and machining of space (in the previous structure, the length of the rotor cavity was equal to or nearly equal to the length of the rotor, which made the machining of the rotor cavity at the exhaust port not convenient and accurate enough). Meanwhile, the rear rotor chamber is located on the end cover. Only after the end cover and the pump casing are connected can the rear rotor chamber and the chamber form a complete rotor chamber to accommodate the rotor. In this structure, when assembling the rotor and the pump body, most of the rotor is installed in the chamber of the pump casing, and a portion of the rotor at the last end of the exhaust end is exposed outside the rear end of the pump casing. This allows the gap between the rotor and the inner wall of the chamber, and the gap between the rotor and the end face of the chamber to be adjusted in advance. After the gap is adjusted, the end cover is installed. Only the gap between the end cover and a small portion of the rotor needs to be fine-tuned, which is convenient for assembly.

[0035] Furthermore, since the exhaust end has the highest temperature, it is most prone to problems, pump jamming, and wear. During use, frequent maintenance, cleaning, repair, and polishing of the exhaust end are required. In previous designs, the entire vacuum pump had to be disassembled for repair (or the entire rear pump casing had to be disassembled). After disassembly, reassembly and debugging were necessary, which was very cumbersome and inefficient. In this embodiment, only the end cover needs to be removed to troubleshoot, maintain, and repair the rear rotor section and the rear rotor cavity of the end cover. Subsequent assembly only requires reassembling the end cover, making it convenient and quick.

[0036] Meanwhile, the pump casing is a one-piece structure. This one-piece structure reduces the number of sealing joints and the risk of leakage. It also facilitates processing, allowing the internal chambers of the pump casing to use the same reference during precision machining, resulting in higher machining accuracy.

[0037] See Figure 3-5 As shown in Figure 7, at least one partition 13 is detachably installed in the chamber 11. The partition 13 divides the chamber 11 into multiple rotor chambers 110 from front to back. The last rotor chamber 110 is used to accommodate the rearmost sub-rotor portion of the rotor. The rear rotor chamber 21 is used to accommodate the sub-rotor exposed at the rear end of the rearmost rotor chamber.

[0038] In this embodiment, two partitions divide the chamber into three chambers, namely, a primary rotor chamber 111, a secondary rotor chamber 112, and a tertiary rotor chamber 113, arranged from front to back. The rotor includes three sub-rotors arranged from front to back: a primary sub-rotor, a secondary sub-rotor, and a tertiary sub-rotor. Adjacent sub-rotors are connected by shafts. A shaft is also provided at the front end of the primary sub-rotor and at the rear end of the tertiary sub-rotor. All shafts are coaxial. The shafts between adjacent sub-rotors are inserted into the partitions (the partitions adopt a two-half structure, which is pre-positioned between adjacent sub-rotors before the rotor with the partitions is installed into the chamber). The primary sub-rotor is completely located in the primary rotor chamber, the secondary sub-rotor is completely located in the secondary rotor chamber, a portion of the tertiary sub-rotor is located in the tertiary rotor chamber, and the remaining portion of the tertiary sub-rotor is inserted into the rear rotor chamber. The foremost shaft is rotatably connected to the first end cover via a bearing, and the rearmost shaft is rotatably connected to the end cover via a bearing. The rotor can be a Roots rotor, meaning all three sub-rotors are Roots rotors. The rotor can also be a hybrid rotor, comprising both Roots and screw rotors. Preferably, the first and second stage sub-rotors are Roots rotors, and the third stage sub-rotor is a screw rotor. Roots rotors offer a large suction capacity, while screw rotors provide a high vacuum. The sub-rotors can be integrated with the shaft or be separate components, mounted on the shaft using fasteners.

[0039] See Figure 2, 4 As shown in Figure 6, the external dimensions of the plurality of rotor cavities 110 decrease sequentially from front to back, and the external dimensions of the rotor cavity 110 located at the front end of the partition 13 are larger than the external dimensions of the rotor cavity 110 located at the rear end of the partition 13.

[0040] In this invention, if the rotor cavities are all the same size, i.e., the inner walls of each rotor cavity are flush, the gap between the outer surface of the sub-rotor and the corresponding inner wall of the rotor cavity is relatively small. This makes installation inconvenient during the rotor insertion into the cavity and can easily scratch the inner wall of the rotor cavity or the sub-rotor. Therefore, in this embodiment, the multiple rotor cavities have a stepped decreasing structure from front to back. When assembling the rotor with the cavity, the rotor is inserted into the cavity from front to back. The outer dimensions of the third-stage sub-rotor are much smaller than those of the first-stage and second-stage rotor cavities, and the outer dimensions of the second-stage sub-rotor are much smaller than those of the first-stage rotor cavity. This facilitates the insertion of each sub-rotor into its corresponding rotor cavity, simplifying assembly and improving assembly efficiency. After all the sub-rotors are installed into their corresponding rotor cavities, the assembly gaps between the first-stage sub-rotor and the first-stage rotor cavity, and between the third-stage sub-rotor and the third-stage rotor cavity, are checked from the front and rear ends of the cavity, and the gaps are adjusted (the gaps between the first-stage sub-rotor, the third-stage sub-rotor and their corresponding first-stage rotor cavity, and the third-stage rotor cavity are adjusted). After the adjustment is completed, the dimensions of the second-stage sub-rotor and the second-stage rotor cavity are also adjusted, thus realizing the assembly of the rotor and the pump casing, gap adjustment, etc.

[0041] In this invention, the size of the last rotor cavity 110 is less than or equal to the size of the rear rotor cavity 21; preferably, in this embodiment, the size of the three-stage rotor cavity is equal to the size of the rear rotor cavity.

[0042] The length of the rear rotor cavity 110 is greater than or equal to the length of the rear rotor cavity 21. Preferably, in this embodiment, the length of the third-stage rotor cavity (the rear rotor cavity) is greater than the length of the rear rotor cavity. More preferably, the length of the third-stage rotor cavity is 2-5 times the length of the rear rotor cavity, wherein the length of the third-stage rotor cavity is 4 / 5-2 / 3 of the length of the third-stage sub-rotor, and the length of the rear rotor cavity is 1 / 5-1 / 3 of the length of the third-stage sub-rotor. More preferably, the length of the rear rotor cavity is 20%-30% of the length of the third-stage sub-rotor. In this structure, after the rotor is installed into the pump casing, only 20%-30% of the length of the third-stage sub-rotor is exposed outside the rear end of the pump casing. This allows for easy adjustment of the gap between the rotor and the pump casing, and most of the position is already adjusted. When installing the end cover later, only the gap between the third-stage sub-rotor and the rear rotor cavity of the end cover needs to be adjusted, making the adjustment convenient and quick.

[0043] See Figure 3-5As shown in Figure 7, each of the partition plates 13 has at least two shaft holes 130 in its middle. The shaft holes are used to accommodate the rotating shafts in the rotor, and the shaft holes 130 connect two adjacent rotor cavities 21. In this embodiment, the vacuum pump is a dual-shaft vacuum pump. Therefore, the partition plate has two shaft holes in its middle, which correspond to the rotating shafts in the two sets of rotors respectively. They are located between adjacent sub-rotors. The rotating shafts between two adjacent sub-rotors are inserted into the corresponding shaft holes, giving the rotating shaft room and not affecting the normal rotation of the rotor to evacuate the vacuum. The partition adopts a symmetrical two-half structure (the partition consists of two symmetrically arranged half-partitions). Each half-partition has two semi-circular holes on its end face. The semi-circular holes of the two half-partitions are positioned opposite each other, forming a shaft hole. During assembly, each half-partition is respectively positioned above and below the shaft between two adjacent sub-rotors of the two sets of rotors. The upper half of each shaft is located within the semi-circular hole of the upper half-partition, and the lower half is located within the semi-circular hole of the lower half-partition. The partition is positioned between adjacent sub-rotors (in this embodiment, the two partitions are respectively positioned between the first-stage and second-stage sub-rotors, and between the second-stage and third-stage sub-rotors). Furthermore, there is a micro-gap between the sidewall of the partition and the end face of the corresponding sub-rotor. This prevents the corresponding sub-rotor from contacting or rubbing against the partition during rotor rotation, preventing wear on the sub-rotor and ensuring smooth rotation. The micro-gap is also small and does not affect vacuuming. The shaft hole provides space for the shaft, does not affect its normal rotation, and facilitates assembly. The baffles simultaneously divide the chamber into multiple independent rotor chambers, enabling the vacuum pump to function as a multi-stage vacuum pump (for example, two baffles result in a three-stage vacuum pump; more baffles create even more stages, such as three baffles for a four-stage vacuum pump). Preferably, the diameter of the shaft hole is slightly larger than the outer diameter of the shaft, and the outer surface of the shaft does not contact the shaft hole. This ensures that the shaft and baffles are not worn during operation, guarantees smooth rotor rotation, reduces energy consumption, and lowers maintenance rates.

[0044] Meanwhile, in this embodiment, since the outer dimensions of the first-stage rotor cavity are larger than those of the second-stage rotor cavity, and the outer dimensions of the second-stage rotor cavity are larger than those of the third-stage rotor cavity, the multiple rotor cavities have a stepped reduction structure from front to back. The two partitions are the first-stage partition and the second-stage partition. The first-stage partition is set inside the first-stage rotor cavity, and the outer edge of its rear end face abuts against the rear end face of the outer edge of the first-stage rotor cavity. The second-stage partition is set inside the second-stage rotor cavity, and the outer edge of its rear end face abuts against the rear end face of the outer edge of the second-stage rotor cavity, thus achieving the installation and positioning of the partitions. Through holes or screw holes are provided on the outer wall of the pump casing, and screw holes are provided on the outer surface of the partitions, which are directly opposite the through holes or screw holes. Bolts pass through the through holes or screw holes on the pump casing and are screwed into the screw holes on the outer surface of the partitions, thus fixing the partitions to the pump casing. More preferably, the connection between the partition and the chamber can be sealed by setting a sealing ring at the outer edge of the rear end face of the partition (the rear end face of the sealing ring contacts the rear end face at the outer edge of the corresponding rotor chamber) to seal the connection between two adjacent rotor chambers. Alternatively, an annular groove can be set on the outer surface of the partition, and a sealing ring can be installed in the annular groove. The outer surface of the sealing ring abuts against the inner wall of the chamber to achieve the seal at the connection between the partition and the chamber.

[0045] See Figure 3-5 As shown, an annular groove 131 is provided on the inner surface of the shaft hole 130. A shaft sealing plate 132 is detachably installed in the annular groove 131. The shaft sealing plate 132 has an annular structure, and the inner surface of the shaft sealing plate 132 is exposed in the shaft hole 130.

[0046] In this embodiment, preferably, the shaft seal is made of PTFE, a flexible and smooth material. Because a gap exists between the inner surface of the shaft hole and the outer surface of the shaft to avoid friction, during vacuuming, some airflow from the secondary rotor cavity will flow back into the primary rotor cavity through this gap, and some airflow from the tertiary rotor cavity will flow back into the secondary rotor cavity through this gap, resulting in noise or affecting the vacuum level. Furthermore, because the shaft in the rotor experiences some shaft runout during rotation, it may collide with the shaft hole during this runout, i.e., the shaft collides with the partition, resulting in rigid metal-to-metal friction (both the shaft and the partition are made of metal), generating noise and causing wear on the shaft. Therefore, a shaft seal is also provided. The inner surface of the shaft seal contacts the outer surface of the shaft, or the inner diameter of the shaft seal is slightly larger than the outer diameter of the shaft (and the inner diameter of the shaft seal is smaller than the inner diameter of the shaft hole). The inner surface of the shaft seal is set close to the outer surface of the shaft (the shaft, shaft hole, and shaft seal are coaxially arranged). This can significantly reduce gas backflow. When the shaft vibrates, it will come into contact with the shaft seal and be blocked by the shaft seal. It will not come into contact with the inner wall of the shaft hole, or only momentarily. The elastic restoring force of the shaft seal also has the thrust to push the shaft back to its original position, thereby preventing rigid friction between the shaft and the shaft hole from generating noise, and will not damage the shaft, or will minimize the damage to the shaft, reduce wear on the shaft (as far as possible, only wear on the shaft seal, which is relatively inexpensive and easy to replace), extend its service life, and reduce the maintenance rate.

[0047] In this invention, the pump housing 1 has multiple connecting air passages that connect adjacent rotor cavities. The inlet of each connecting air passage is connected to the bottom of the front rotor cavity 11, and the outlet of each connecting air passage is connected to the top, side, or front end of the adjacent rear rotor cavity 110.

[0048] In this embodiment, a primary rotor chamber, a secondary rotor chamber, and a tertiary rotor chamber (a primary Roots rotor chamber, a secondary Roots rotor chamber, and a tertiary screw rotor chamber, with the main air inlet connected to the top of the primary Roots rotor chamber) are provided. Therefore, two connecting air passages are provided (if there are four rotor chambers, three connecting air passages are provided, with the number of connecting air passages being one less than the number of rotor chambers), namely a primary connecting air passage 141 and a secondary connecting air passage 142. The primary connecting air passage connects the primary rotor chamber and the secondary rotor chamber, and the secondary connecting air passage connects the secondary rotor chamber and the tertiary rotor chamber. In this embodiment, the inlet of the primary connecting air passage is connected to the bottom of the primary rotor chamber, and the outlet of the primary connecting air passage is connected to the top of the secondary rotor chamber. The inlet of the secondary connecting air passage is connected to the bottom of the secondary rotor chamber, and the outlet is connected to the bottom, top, front end, or side of the tertiary rotor chamber. The primary connecting air passage is located inside the pump casing outside the chamber. The main air inlet is used to connect to the equipment, components, pipelines, or other places requiring vacuuming. During operation, the two sets of rotors rotate simultaneously in opposite directions, both facing inwards. This draws the gas from the main air inlet into the primary rotor chamber above the two sets of primary sub-rotors (Roots rotors). The gas is then compressed downwards and sent into the primary rotor chamber below the two sets of primary sub-rotors (Roots rotors), and into the inlet of the primary connecting air passage at the bottom of the primary rotor chamber. It then passes through the primary connecting air passage surrounding the pump casing outside the chamber and into the secondary rotor chamber above the two sets of secondary sub-rotors (Roots rotors). The rotation of the two sets of secondary sub-rotors then sends the gas into the secondary rotor chamber below the two sets of secondary sub-rotors. Finally, through the secondary connecting air passage, the gas is sent into the tertiary rotor chamber. The tertiary sub-rotor (screw rotor) then sends the gas from front to back into the rear rotor chamber and discharges it from the exhaust port.

[0049] More preferably, an inspection port 18 communicating with the primary connecting air passage is provided on the outer wall of the pump casing, and a detachable inspection cover is installed on the inspection port (the inspection cover is not shown). The presence of the inspection port facilitates the inspection and cleaning of the interior of the primary connecting air passage.

[0050] In this invention, the rotor chamber is a Roots rotor chamber and / or a screw rotor chamber. In this embodiment, the last rotor chamber is a screw rotor chamber, and the rotor chambers preceding the screw rotor chamber are Roots rotor chambers, making the vacuum pump a hybrid vacuum pump. Of course, all rotor chambers can also be Roots rotor chambers, i.e., the vacuum pump is a multi-stage Roots vacuum pump. In this embodiment, the last rotor chamber and the rear rotor chamber are screw rotor chambers used to accommodate the screw rotor; the two rotor chambers preceding the screw rotor chamber are both Roots rotor chambers used to accommodate the Roots rotors.

[0051] In this embodiment, the secondary connecting air passage is directly set on the bottom surface of the chamber (or it can be set inside the pump casing outside the chamber). Its inlet is set at the bottom of the secondary rotor chamber at the front end of the rear end partition, and its outlet is set at the bottom of the tertiary rotor chamber at the rear end of the rear end partition. The gas delivered from the secondary rotor chamber is sent into the front end of the tertiary rotor chamber through the secondary connecting air passage. Then, through the meshing of two sets of screw rotors (tertiary sub-rotors), the gas is compressed and transported backward and sent out from the exhaust port.

[0052] In this embodiment, see Figure 7 As shown, the bottom of the last-end partition 13 is provided with a notch 133, which connects the bottom of the last-end rotor cavity 110 and the bottom of the adjacent front rotor cavity 110. Preferably, the notch is connected to the secondary connecting air passage. The presence of the notch can increase the amount of air fed from the secondary rotor cavity to the tertiary rotor cavity. This results in a larger gas flow rate and a lower flow velocity from the secondary rotor cavity to the tertiary rotor cavity, thereby reducing the temperature at that location. Furthermore, the lower gas flow velocity further reduces the impact force of the gas on the tertiary sub-rotor (screw rotor), extending its service life and reducing the maintenance rate.

[0053] Further, see Figure 2 As shown, in this embodiment, the rear rotor cavity 110 adopts a screw rotor cavity, and the rear rotor cavity also adopts a screw rotor cavity. To facilitate gas entry from the front end of the screw rotor, the contact between the gas and the screw rotor is axially released, preventing problems such as excessively high temperature in the rear rotor cavity and easy deformation of the shaft (in the prior art, such as application number "202421278655.0", patent title "A Two-Shaft Mixing Pump", the gas in the Roots rotor cavity is sent into the screw rotor cavity, and the gas directly impacts the outer surface of the screw rotor. The impact direction is perpendicular to the axis of the shaft, and the shaft is subjected to radial force from the gas for a long time, which easily leads to shaft deformation (even slight deformation). After the shaft is deformed, it will also cause the two screw rotors to rub against each other, or the screw rotor and the screw rotor cavity to rub against each other, resulting in jamming and wear, leading to high maintenance rates). The high efficiency and short service life of the three-stage screw rotor are problems. Furthermore, because the screw rotor has a helical structure, the helical gaps within the helical structure form the gas flow path. Due to the radial air intake, the gas entering the screw rotor cavity can only enter from a portion of the helical grooves, resulting in higher exhaust pressure during vacuuming, higher temperatures within the screw rotor cavity, and greater radial pressure of the airflow on the shaft at that point. This leads to problems such as a short service life and high maintenance rate for the three-stage screw rotor. Therefore, a cavity 114 is provided between the rotor cavity 110 at the rear end and the partition 13 (secondary partition) at the rear end. The outlet of the connecting air passage (secondary connecting air passage) at the rear end communicates with this cavity, and the notch 133 also communicates with the cavity 114.

[0054] In this embodiment, a cavity is provided, but the third-stage sub-rotor (the last sub-rotor) is not located within the cavity. That is, there is a cavity between the third-stage sub-rotor and the rear partition (secondary partition). This allows the gas from the secondary rotor cavity, after passing through the secondary connecting air passage and the notch (when the two sets of secondary sub-rotors rotate, the gas in the secondary rotor cavity above the secondary sub-rotor is sent to the secondary rotor cavity below the secondary sub-rotor, and then into the secondary air passage; the secondary sub-rotor is a Roots rotor), to enter the cavity. The gas can be evenly distributed within this cavity and easily enters from the front end face of the third-stage sub-rotor (screw rotor) along the spiral groove of the third-stage sub-rotor. The gas can fully contact the front end face of the spiral groove of the third-stage sub-rotor, reducing the pressure of the gas from the secondary rotor cavity entering the spiral groove of the third-stage sub-rotor, reducing the impact force on the third-stage sub-rotor, and also lowering the overall temperature of the third-stage rotor cavity, extending its service life and reducing the maintenance rate. Furthermore, preferably, the outlet of the secondary connecting air passage is positioned directly opposite the gap between the two rotating shafts. This prevents radial impact on the rotating shafts when gas enters the cavity, effectively preventing shaft deformation, extending service life, and reducing maintenance rate. Simultaneously, the cavity ensures uniform gas distribution within the tertiary rotor cavity, dispersing the impact force on the tertiary sub-rotor, further extending service life and reducing maintenance rate. (Of course, if the tertiary sub-rotor is a Roots rotor, the cavity is unnecessary; the outlet of the secondary connecting air passage is connected to the top of the tertiary rotor cavity. In this embodiment, the primary and secondary sub-rotors are Roots rotors, and the tertiary sub-rotor is a screw rotor.)

[0055] In another embodiment, all the rotor chambers and the rear rotor chamber are screw rotor chambers; a cavity is also provided between each rotor chamber and the corresponding front-end partition of the rotor chamber; the inlet of each connecting air passage is connected to the rear bottom or rear end face of the adjacent front rotor chamber, and the outlet of each connecting air passage is connected to the adjacent rear cavity. In this structure, the gas fed from the front rotor chamber into the adjacent rear rotor chamber will not directly cause radial impact on the sub-rotor (screw rotor), and the gas can also fully contact the inlet of the sub-rotor (the contact area of ​​the helical groove on the front end face of the screw rotor is the largest), reducing the occurrence of air stagnation and high temperature.

[0056] See Figure 2 As shown, the main air inlet 12 is connected to the top of the foremost rotor cavity 110 (first-stage rotor cavity); A bypass channel 15 is also provided, which is located inside the pump housing 1 and / or outside the pump housing 1; The inlet of the bypass channel 15 is connected to the bottom of the frontmost rotor cavity 110, and the outlet of the bypass channel 15 is connected to the outer wall of the pump casing 1 or the outer wall of the end cover 2.

[0057] In this embodiment, a portion of the bypass channel is located outside the pump casing, and a portion is located inside the pump casing. The portion located outside the pump casing is a bypass pipe, and the portion located inside the pump casing is a bypass groove. The bypass pipe and the bypass groove are connected. Alternatively, only one bypass groove can be provided, located inside the pump casing; or only one bypass pipe can be provided, located outside the pump casing. One end of the bypass channel is an inlet, connected to the bottom of the first-stage rotor chamber, preferably connected to the inlet of the first-stage connecting air passage. The other end of the bypass channel is an outlet, connected to the outer wall of the end cover or the outer wall of the pump casing.

[0058] In this invention, the bypass channel outlet has two structures. The first type is directly connected to the outer wall of the pump casing. In this structure, a one-way pressure relief valve 16 needs to be installed in the middle of the bypass channel. With the one-way pressure relief valve, when the exhaust pressure in the primary rotor chamber is greater than the pressure in the secondary rotor chamber, and the pressure value is greater than the opening pressure required by the one-way pressure relief valve, the one-way pressure relief valve opens to discharge gas until the gas pressure drops to a predetermined value, at which point the one-way pressure relief valve closes. This prevents internal pressure buildup in the primary and secondary rotor chambers of the vacuum pump. This one-way pressure relief valve can be a one-way pressure relief valve with a pressure relief ball structure (the pressure relief ball falls under gravity and presses against the bottom hole, closing the bypass channel; when the gas pressure is greater than the weight of the pressure relief ball, it pushes the pressure relief ball upward, opening the hole, thus opening the bypass channel), such as the one-way valve structure in application number "202422334498.7", patent title "A Pump Body of a Hybrid Vacuum Pump".

[0059] The second structure has the bypass channel outlet connected to the outer wall of the end cover. In this structure, an end pressure relief channel 23 is provided on the front end face of the end cover 2. The end pressure relief channel 23 is located beside or around the rear rotor cavity 21, and the inlet of the end pressure relief channel 23 is connected to the outlet of the bypass channel 15. The second structure also includes the following three sub-structures: A. The outlet of the end pressure relief channel is connected to the outer wall of the end cover. A one-way pressure relief valve is also required in the middle of the bypass channel, and its operation is the same as in the first structure. In this structure, the rear end face of the bypass channel is connected to the rear end face of the pump housing and faces the end pressure relief channel. After the end cover and pump housing are installed, the bypass channel and the end pressure relief channel are connected, and the gas depressurized by the bypass channel is discharged from the end pressure relief channel.

[0060] B. The top of the end cap 2 is provided with a pressure relief chamber 24. One end of the pressure relief chamber 24 is connected to the outlet of the end pressure relief channel 23, and the other end of the pressure relief chamber 24 is connected to the outer wall of the end cap 2. A pressure relief device 25 is detachably installed in the pressure relief chamber, and no one-way pressure relief valve is provided in the bypass channel 15.

[0061] C. A pressure relief chamber 24 is provided on the top of the end cap 2. One end of the pressure relief chamber 24 is connected to the outlet of the end pressure relief channel 23, and the other end of the pressure relief chamber 24 is connected to the outer wall of the end cap 2. A pressure relief device 25 is detachably installed in the pressure relief chamber 24, and a one-way pressure relief valve 16 is also provided in the bypass channel. In this embodiment, this structure is adopted, that is, a combination of a pressure relief chamber, a pressure relief device, and a one-way pressure relief valve.

[0062] See Figure 2 , 8 As shown in Figure -10, the pressure relief chamber 24 is connected to the end pressure relief channel 23 via at least one connecting hole 26, and the pressure relief chamber 24 is connected to the outer wall of the end cover 2 via the pressure relief bypass channel 27; preferably, the pressure relief bypass channel is connected to the exhaust port for easy processing.

[0063] The pressure relief device 25 includes a pressure relief housing 251 and pressure relief balls 252. The number of pressure relief balls 252 matches the number of connecting holes 26. A connecting cavity 253 is provided inside the pressure relief housing 251. The bottom of the pressure relief housing 251 has a first hole 254 and a second hole 255 communicating with the connecting cavity 253. The first hole 254 is positioned directly opposite the pressure relief bypass channel 27. Each second hole 255 is positioned directly opposite one of the connecting holes 26. 4. The connecting cavity 253 is connected to the pressure relief bypass channel 27, and the second hole 255 is connected to the corresponding connecting hole 26 and the connecting cavity 253; the pressure relief ball 252 is housed in the connecting cavity 253, and each pressure relief ball 252 is positioned opposite a second hole 255; when the pressure relief ball 252 is under gravity (subject to its own weight), the bottom outer surface of the pressure relief ball 252 abuts against the top inner surface of the second hole 255, and closes the second hole 255.

[0064] When the gas pressure at the bottom of the pressure relief ball 252 exceeds a preset value, the pressure relief ball 252 moves upward and opens the top of the second hole 255, so that the connecting hole 26 is connected to the pressure relief bypass channel 27 through the second hole 255, the connecting cavity 253, and the first hole 254.

[0065] In this embodiment, the end pressure relief channel is arranged outside the rear rotor cavity. Its shape can be similar to the shape of the rear rotor cavity, so that the end cover is as symmetrical as possible, which is more beautiful and easier to process. Of course, the end pressure relief channel can also be set only on the outside of one side of the rear rotor cavity, which does not affect the normal use of the end pressure relief channel.

[0066] Preferably, in this embodiment, three connecting holes are spaced apart to connect the end pressure relief channel and the pressure relief chamber, improving pressure relief efficiency. The top inner surface of the second hole is arc-shaped, matching the outer surface of the pressure relief ball. Simultaneously, when the bottom of the pressure relief ball abuts against the top inner surface of the second hole, the distance between the top of the pressure relief ball and the top surface of the connecting cavity is less than the radius of the pressure relief ball. Even when the pressure relief ball is lifted, if its top contacts the top surface of the connecting cavity, the bottom of the pressure relief ball will be directly opposite the second hole, or the bottom of the pressure relief ball will still be inside the second hole, but with a gap between it and the top inner surface of the second hole. This ensures that when the pressure relief ball loses gas pressure, it will automatically fall and close the second hole. During vacuum pump operation, if the gas pressure in the primary rotor chamber is too high (or exceeds atmospheric pressure), or if this pressure value is greater than the pressure relief pressure of the one-way pressure relief valve, or greater than the weight of the pressure relief ball in the one-way pressure relief valve, the one-way pressure relief valve will open, discharging gas into the end pressure relief channel. If the gas pressure in the end pressure relief channel exceeds the weight of the pressure relief ball in the pressure relief device, it will push the ball up, causing the gas in the end pressure relief channel to be discharged into the connecting cavity through the connecting hole and the second hole, then into the pressure relief bypass channel through the first hole, and finally out of the exhaust port. This effectively prevents gas from accumulating pressure at the outlet of the first-stage rotor cavity and the inlet of the second-stage rotor cavity (pressure buildup inside the vacuum pump), thereby reducing the energy consumption of the vacuum pump during operation, extending its service life, and minimizing damage to the motor driving the vacuum pump, thus extending its service life as well. Furthermore, without pressure buildup, the vacuum pump does not need to compress this gas additionally, saving energy and preventing excessive temperature rise that could affect the service life of the vacuum pump.

[0067] See Figure 8-10 As shown, the top of the connecting cavity 253 communicates with the top of the pressure relief housing 251. A pressure relief cover 256, which closes the top of the connecting cavity 253, is detachably installed on the top of the pressure relief housing 251. The presence of the pressure relief cover allows for easy maintenance by simply opening the cover, eliminating the need to remove the pressure relief device from the end cover during maintenance.

[0068] In this embodiment, the pressure relief housing and the pressure relief cover are made of stainless steel. The end cap and pump housing are made of cast iron, while the pressure relief housing and cover are made of stainless steel. The different material of stainless steel prevents rust and corrosion, ensuring that the sealing performance between the pressure relief housing and the pressure relief chamber is not affected (the connection between the pressure relief housing and the pressure relief chamber needs to be sealed to prevent gas leakage from the connection hole). This also facilitates the disassembly of the entire pressure relief device for maintenance, replacement, and cleaning. Furthermore, depending on the situation, the pressure relief ball can be selectively removed from the device; if the ball is not needed, only the one-way pressure relief valve can be used for pressure relief, allowing for convenient and flexible adjustment.

[0069] See Figure 9 As shown, a bearing cavity 28 is provided on the rear end face of the end cover 2, and the bearing cavity 28 is connected to the rear rotor cavity 21 through the shaft hole 29.

[0070] The bearing cavities are used to install bearings. In this embodiment, there are two bearing cavities 28, which are connected to the rear rotor cavity 21 through a shaft hole 29, respectively. The diameter of the shaft hole 29 is smaller than the diameter of the bearing cavity 28. More preferably, two lip-shaped sealing cavities 201 are also provided on the rear end face of the rear rotor cavity. Each lip-shaped sealing cavity is coaxially disposed at the outer edge of a rotor hole. The presence of the lip-shaped sealing cavities is used for the installation of lip seals to seal the connection between the shaft hole and the shaft, preventing lubricating oil on the bearing from entering the rear rotor cavity and affecting the normal operation of the vacuum pump.

[0071] More preferably, a static sealing ring can be fitted onto the shaft that is located in the shaft hole to further improve the sealing effect.

[0072] Furthermore, a bearing cooling water channel 202 is provided inside the end cover 2 outside the bearing cavity 28. The outer wall of the end cover 2 has a bearing cooling water inlet and a bearing cooling water outlet communicating with the bearing cooling water channel 202. Since the lip seal and / or static seal are made of rubber or plastic, they generate high temperatures during bearing and vacuum pump operation. Higher temperatures lead to faster aging and affect the reliability of the vacuum pump. Therefore, a bearing cooling water channel is provided. This channel is large, allowing for a large volume of cooling medium and better heat dissipation. It also reduces the overall material and weight of the end cover, resulting in a lighter and more compact vacuum pump. Because it is not connected to the rotor cavity or rear rotor cavity inside the vacuum pump, the cooling medium flowing out will not damage the internal parts during maintenance and repair. Simultaneously, due to heat transfer, it also cools the end cover, allowing for temperature control at the exhaust end, reducing the vacuum pump's maintenance rate and extending its service life.

[0073] Furthermore, a jacketed water chamber 17 is also provided inside the pump casing 1 outside the rotor cavity 110 at the last end; The outer wall of the pump casing 1 is provided with an inlet and an outlet that communicate with the jacketed water chamber 17.

[0074] The jacketed water chamber is also relatively large, allowing for the introduction of more cooling medium, resulting in better heat dissipation and reducing the overall weight and material usage of the pump casing. Because it is independently configured, the cooling medium flowing out during maintenance and repair will not damage the internal components of the vacuum pump. Furthermore, its independent configuration from the bearing cooling water chamber enables segmented temperature control of the vacuum pump, facilitating its application in various processes.

[0075] In the description of this invention, it should be understood that the terms "upper," "lower," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0076] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. For instance, the two components can be mechanically connected by contact or abutting; they can also be directly hooked or connected by an intermediate medium; or they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

Claims

1. A pump body, characterized in that: include: The pump casing has a chamber extending through both ends in the axial direction. The chamber is used to accommodate part of the rotor. The front outer wall of the pump casing has a main air inlet that communicates with the chamber. An end cover is provided at the rear end of the pump housing and closes the rear end of the chamber; a rear rotor cavity is provided on the front end face of the end cover facing the chamber, and the rear rotor cavity accommodates the rotor exposed at the rear end of the chamber; an exhaust port communicating with the rear rotor cavity is provided on the outer wall of the end cover.

2. The pump body according to claim 1, characterized in that: At least one partition is detachably installed in the chamber, which divides the chamber into multiple rotor chambers from front to back. The last rotor chamber is used to accommodate the rearmost sub-rotor portion of the rotor, and the rear rotor chamber is used to accommodate the sub-rotor exposed at the rear end of the rearmost rotor chamber.

3. The pump body according to claim 2, characterized in that: The dimensions of the plurality of rotor cavities decrease sequentially from front to back, and the size of the rotor cavity located at the front end of the partition is larger than the size of the rotor cavity located at the rear end of the partition.

4. The pump body according to claim 2, characterized in that: The size of the rotor cavity at the rear end is less than or equal to the size of the rear rotor cavity; And / or, the length of the rear rotor cavity is greater than or equal to the length of the rear rotor cavity.

5. The pump body according to claim 2, characterized in that: Each of the partitions has at least two shaft holes in its middle, the shaft holes being used to accommodate the rotating shaft in the rotor, and the shaft holes connecting two adjacent rotor cavities.

6. The pump body according to claim 5, characterized in that: An annular groove is provided on the inner surface of the shaft hole, and a shaft sealing plate is detachably installed in the annular groove, with the inner surface of the shaft sealing plate exposed inside the shaft hole.

7. The pump body according to claim 2, characterized in that: The pump casing has multiple connecting air passages that connect adjacent rotor cavities.

8. The pump body according to claim 7, characterized in that: The inlet of the connecting air passage is connected to the bottom of the front rotor cavity, and the outlet of the connecting air passage is connected to the top, side or front of the adjacent rear rotor cavity.

9. The pump body according to claim 2 or 7, characterized in that: The bottom of the last partition plate has a notch that connects the bottom of the last rotor cavity to the bottom of the adjacent front rotor cavity.

10. The pump body according to claim 2, characterized in that: The rotor cavity is a Roots rotor cavity and / or a screw rotor cavity.

11. The pump body according to claim 7, characterized in that: The rotor cavity at the last end and the rear rotor cavity are screw rotor cavities; A cavity is provided between the rotor cavity at the rear end and the partition at the rear end, and the outlet of the connecting air passage at the rear end is connected to the cavity.

12. The pump body according to claim 7, characterized in that: All of the rotor cavities and the rear rotor cavity are screw rotor cavities; a cavity is also provided between each rotor cavity and the partition plate at the front end of the corresponding rotor cavity. The inlet of each of the connecting air passages is connected to the rear bottom or rear end face of the adjacent front rotor cavity, and the outlet of each of the connecting air passages is connected to the adjacent rear cavity.

13. The pump body according to claim 2, characterized in that: The main air inlet is connected to the top of the rotor cavity at the foremost end; A bypass channel is also provided, which is located inside and / or outside the pump casing; The inlet of the bypass channel is connected to the bottom of the frontmost rotor cavity, and the outlet of the bypass channel is connected to the outer wall of the pump casing or the outer wall of the end cover.

14. The pump body according to claim 13, characterized in that: A one-way pressure relief valve is provided in the middle of the bypass channel.

15. The pump body according to claim 13 or 14, characterized in that: The end cap has an end pressure relief channel on its front end surface. The end pressure relief channel is located on the side or periphery of the rear rotor cavity. The inlet of the end pressure relief channel is connected to the outlet of the bypass channel.

16. The pump body according to claim 15, characterized in that: The outlet of the end pressure relief channel is connected to the outer wall of the end cap.

17. The pump body according to claim 15, characterized in that: The top of the end cap is provided with a pressure relief chamber. One end of the pressure relief chamber is connected to the outlet of the end pressure relief channel, and the other end of the pressure relief chamber is connected to the outer wall of the end cap.

18. The pump body according to claim 17, characterized in that: The pressure relief chamber is connected to the end pressure relief channel via at least one connecting hole, and the pressure relief chamber is connected to the outer wall of the end cover via a pressure relief bypass channel; A pressure relief device is detachably installed in the pressure relief chamber. The pressure relief device includes a pressure relief shell and pressure relief balls. The number of pressure relief balls matches the number of connection holes. The pressure relief shell has a connection cavity. The bottom of the pressure relief shell has a first hole and a second hole communicating with the connection cavity. The first hole is positioned opposite the pressure relief bypass channel. Each second hole is positioned opposite a connection hole. The first hole connects the connection cavity and the pressure relief bypass channel, and the second hole connects the corresponding connection hole and the connection cavity. The pressure relief balls are housed in the connection cavity, and each pressure relief ball is positioned opposite a second hole. Under gravity, the bottom outer surface of the pressure relief ball abuts against the top inner surface of the second hole, closing the second hole.

19. The pump body according to claim 18, characterized in that: When the gas pressure at the bottom of the pressure relief ball exceeds a preset value, the pressure relief ball moves upward and opens the top of the second hole, so that the connecting hole connects to the pressure relief bypass channel through the second hole, the connecting cavity, and the first hole.

20. The pump body according to claim 18, characterized in that: The top of the connecting cavity is connected to the top of the pressure relief housing, and the top of the pressure relief housing is detachably equipped with a pressure relief cover plate to close the top of the connecting cavity; And / or, the pressure relief housing and the pressure relief cover are made of stainless steel.

21. The pump body according to claim 1, characterized in that: The end cap has a bearing cavity on its rear end face, and the bearing cavity is connected to the rear rotor cavity through a shaft hole.

22. The pump body according to claim 21, characterized in that: The bearing cooling water channel is provided inside the end cover outside the bearing cavity, and the outer wall of the end cover is provided with a bearing cooling water inlet and a bearing cooling water outlet that communicate with the bearing cooling water channel.

23. The pump body according to claim 2, characterized in that: A jacketed water chamber is also provided inside the pump casing outside the rotor cavity at the last end; And / or, the outer wall of the pump casing is provided with an inlet and an outlet that communicate with the jacketed water chamber.

24. The pump body according to claim 1, characterized in that: The pump casing is a one-piece structure.

25. A vacuum pump, characterized in that: It also includes the pump body as described in any one of claims 1-24.

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