Double-rotor roots vacuum pump

Abstract

The utility model discloses a double-rotor roots vacuum pump which comprises a shell assembly, a first driving shaft, a second driving shaft and a synchronous parallel motor, wherein the first driving shaft, the second driving shaft and the synchronous parallel motor are located in the shell assembly. A motor mounting area, a working area and a supporting area which are axially connected are arranged in the shell assembly, each of the first driving shaft and the second driving shaft comprises a middle section and supporting sections located at the two ends of the middle section, and a pump cavity is defined by the middle sections and the working area. One of the supporting sections of the two driving shafts is matched with the synchronous parallel motor at the same time to be assembled in the motor installation area, the other supporting section of the two driving shafts is assembled in the supporting area, and the two supporting sections of the two driving shafts achieve fixed supporting through supporting bearings. The first driving shaft and the second driving shaft are driven by the connected stator and are not separated from a driving shaft and a driven shaft, the transmission efficiency of the double shafts is high, and due to the fact that no transmission exists between the first driving shaft and the second driving shaft, the novel structure is not provided with a gear and a gear box, and the risk of oil leakage can be completely eradicated.

Description

Technical Field

[0001] The utility model relates to the technical field of vacuum pump design, in particular to a two-rotor Roots vacuum pump. Background Art

[0002] A Roots vacuum pump is a two-rotor vacuum pump. There are two rotors with symmetrical shapes in the pump cavity, and the two rotors are installed on a pair of parallel shafts according to a certain phase.

[0003] In a traditional Roots vacuum pump, the two parallel shafts are divided into a driving shaft and a driven shaft. An external motor drives the driving shaft to rotate, and the driving shaft and the driven shaft are driven by a gear meshing method. This structure places high demands on the strength of the driving shaft, and there is also energy loss during the transmission process, resulting in a decrease in the efficiency of the Roots vacuum pump.

[0004] Therefore, the prior art proposes a vacuum pump structure with an embedded motor provided in two parallel shafts. Each shaft is driven by its respective embedded motor. On the one hand, the size of the vacuum pump can be reduced, and on the other hand, the energy loss caused by the transmission process can be avoided. However, since the two embedded motors are not related to each other, in order to ensure the synchronous operation of the two shafts, it is necessary to improve the phenomenon of asynchronous movement through the meshing of phase gears. Therefore, there are also bearing seals for the gearbox and connecting gears in this solution.

[0005] Because the Roots vacuum pump of the prior art has gears and a gearbox, there is a risk of oil leakage during its operation. The gears in the gearbox need to be lubricated to ensure the transmission accuracy. To avoid lubricating oil loss, the gearbox and the pump cavity of the Roots pump are sealed by dynamic sealing elements. After the Roots pump operates, a certain vacuum degree is formed in the pump cavity, and there will be a pressure difference between the gearbox and the pump cavity. Under the action of the pressure difference, the lubricating oil in the gearbox will enter the pump cavity along the shaft seal. Only when the pressures in the gearbox and the pump cavity reach an equilibrium state will the lubricating oil stop entering the pump cavity. With the long-term operation of the Roots pump, the lubricating oil in the gearbox will gradually be sucked into the pump cavity and slowly drop below the standard liquid level. At this time, if lubricating oil needs to be added, the machine must be stopped, otherwise the lubricating oil in the gearbox will be quickly sucked into the pump cavity due to the pressure difference between the atmosphere and the pump cavity. For working conditions that require long-term continuous operation, the Roots pump with a gearbox is not suitable.

[0006] Currently, the main method adopted is to strengthen the bearing seal requirements inside the gearbox, so the sealing structure at the bearing is difficult to assemble, and it is not convenient for disassembly and maintenance.

[0007] To sum up, how to design a two-rotor Roots vacuum pump with low assembly difficulty and capable of avoiding the risk of oil leakage, so as to achieve long-term stable operation, is a technical problem that needs to be solved currently. Summary of the Utility Model

[0008] In order to solve the technical problems in the prior art that the twin-rotor Roots vacuum pump has high assembly difficulty, has the risk of oil leakage, needs to be shut down regularly to add lubricating oil, and cannot work stably for a long time, the utility model provides a twin-rotor Roots vacuum pump to solve the above problems.

[0009] The utility model solves the technical problem by adopting a technical solution: a double-rotor Roots vacuum pump comprises a shell component and a first drive shaft, a second drive shaft and a synchronous parallel motor located inside the shell component.

[0010] The housing assembly comprises an axially connected motor installation area, a working area and a support area. The first drive shaft and the second drive shaft each comprise an intermediate section and support sections at both ends of the intermediate section. The intermediate section and the working area form a pump cavity. One of the support sections of the two drive shafts is assembled in the motor installation area in cooperation with the synchronous parallel motor, and the other support section is assembled in the support area. Both support sections of the two drive shafts are fixedly supported by support bearings.

[0011] Furthermore, the shell assembly includes an outer shell and a front end cover and a rear end cover located at both ends of the outer shell. The outer shell has cover plates at both ends. The two cover plates separate the shell assembly into a motor installation area, a working area and a support area. The first drive shaft and the second drive shaft both pass through the two cover plates. The front end cover and the outer shell enclose the motor installation area.

[0012] Furthermore, the synchronous parallel motor includes a connected stator, a first rotor and a second rotor, the first rotor is fixed outside the first drive shaft, the second rotor is fixed outside the second drive shaft, and the first drive shaft and the second drive shaft are simultaneously matched with the connected stator.

[0013] Furthermore, a water inlet and a water outlet are provided on the main body of the shell, and two cover plates are fixed to the main body of the shell by screws.

[0014] Furthermore, the front end cover is snap-fitted or interference-fitted with the outer peripheral surface of the shell.

[0015] Furthermore, a mounting frame is fixed on the cover plate that encloses the motor mounting area, and the integrated stator is clamped between the mounting frame and the front end cover.

[0016] Furthermore, the support bearing includes a first support bearing, a second support bearing and a third support bearing. The support sections at one end of the two drive shafts are supported on the front end cover through the first support bearing and on the mounting frame through the second support bearing. The support sections at the other end of the two drive shafts are supported on the cover plate that encloses the support area through the third support bearing.

[0017] Furthermore, the rear end cover is fixed to the end surface of the cover plate that encloses the support area by screws.

[0018] Furthermore, the diameter of the supporting section is smaller than the diameter of the middle section.

[0019] Furthermore, the support section includes a bearing mounting section and a limiting section, the limiting section is located between the bearing mounting section and the middle section, the diameters of the middle section, the limiting section and the bearing mounting section decrease successively, the support bearing is assembled on the bearing mounting section, and the limiting section limits the axial position of the support bearing.

[0020] The beneficial effects of the utility model are:

[0021] (1) The first drive shaft and the second drive shaft in the utility model are driven by a connected stator, and there is no distinction between a driving shaft and a driven shaft. The transmission efficiency of the two shafts is high. Moreover, since there is no transmission between the first drive shaft and the second drive shaft, there are no gears and gear boxes between the two drive shafts of the new structure, which can completely eliminate the risk of oil leakage.

[0022] (2) The utility model sets the synchronous parallel motor at one end of the drive shaft. Compared with the motor embedded in the drive shaft, the utility model has better heat dissipation effect and is easy to disassemble and repair. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The utility model is further described below in conjunction with the accompanying drawings and embodiments.

[0024] Figure 1 It is a stereogram of a specific implementation of the double-rotor Roots vacuum pump described in the utility model;

[0025] Figure 2 This is an axial cross-sectional view of the double-rotor Roots vacuum pump described in the utility model;

[0026] Figure 3 It is a three-dimensional diagram of the double-rotor Roots vacuum pump of the utility model after the front end cover is removed;

[0027] Figure 4 It is a stereoscopic diagram of the twin-rotor Roots vacuum pump of the utility model after removing the front end cover and the synchronous parallel motor.

[0028] In the figure, 1, shell assembly, 101, shell, 1011, cover plate, 1012, body, 102, front cover, 103, rear cover, 2, first drive shaft, 3, second drive shaft, 4, synchronous parallel motor, 401, connected stator, 402, first rotor, 403, second rotor, 5, motor installation area, 6, working area, 7, support area, 8, middle section, 9, support section, 901, bearing installation section, 902, limit section, 10, water inlet, 11, water outlet, 12, mounting frame, 13, first support bearing, 14, second support bearing, 15, third support bearing. DETAILED DESCRIPTION

[0029] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0030] like Figure 1 , Figure 2 As shown, a twin-rotor Roots vacuum pump includes a housing assembly 1 and a first drive shaft 2, a second drive shaft 3 and a synchronous parallel motor 4 located inside the housing assembly 1. The housing assembly 1 forms a closed cavity, and the remaining components are installed in the closed cavity. The first drive shaft 2 and the second drive shaft 3 are arranged in parallel, and the synchronous parallel motor 4 is located at one end of the first drive shaft 2 and the second drive shaft 3.

[0031] The housing assembly 1 has an axially connected motor installation area 5, a working area 6 and a support area 7. The axial connection means that the three areas are arranged in sequence along the axial direction. The first drive shaft 2 and the second drive shaft 3 each include an intermediate section 8 and support sections 9 located at both ends of the intermediate section 8. The intermediate section 8 and the working area 6 form a pump cavity. One of the support sections 9 of the two drive shafts is simultaneously assembled in the motor installation area 5 in cooperation with the synchronous parallel motor 4, and the other support section 9 is assembled in the support area 7. The two support sections 9 of the two drive shafts are fixedly supported by support bearings.

[0032] The synchronous parallel motor 4 refers to a motor with a connected stator 401, which realizes the synchronous rotation of the two rotors. The utility model assembles two drive shafts with the synchronous parallel motor 4, and does not require gear transmission to ensure rotation synchronism. Therefore, it is not necessary to install gears and gear boxes between the two drive shafts, and it is not necessary to add lubricating oil, thereby completely eliminating the risk of oil leakage.

[0033] Compared with the traditional Roots vacuum pump in which the motor is only connected to one drive shaft, the utility model improves the transmission efficiency and reduces the strength requirements of the drive shaft. Since the winding process of the synchronous parallel motor 4 is relatively complicated, the synchronous parallel motor 4 has not been used in the Roots vacuum pump before, and the problems of oil leakage and low transmission efficiency are only alleviated by strengthening the seal or embedding the motor. However, in fact, the use of the synchronous parallel motor 4 can bring more beneficial effects from the side. For example, compared with the embedded motor structure, the utility model has better heat dissipation effect because the synchronous parallel motor 4 is arranged in an independent motor installation area 5, which can greatly improve the service life of the motor. In addition, compared with the bearing structure assembled at the gear, the support bearing in the utility model mainly plays a supporting and fixing role, and does not need to play a sealing role. Therefore, the bearing structure is simpler. Although the number of bearings has not been reduced, the assembly process is greatly simplified. More importantly, the use of the Roots vacuum pump described in the utility model can completely solve the oil leakage problem, and there is no need to stop the machine to add lubricating oil, thereby achieving long-term stable operation and avoiding the economic losses caused by multiple shutdowns and startups of the traditional structure.

[0034] The housing assembly 1 may, but is not limited to, adopt the following structure: Figure 1 and Figure 2 As shown, it includes a housing 101 and a front cover 102 and a rear cover 102 located at both ends of the housing 101. The housing 101 has cover plates 1011 at both ends. The two cover plates 1011 separate the housing assembly 1 into a motor installation area 5, a working area 6 and a support area 7. The first drive shaft 2 and the second drive shaft 3 both pass through the two cover plates 1011. The front cover 102 and the housing 101 enclose the motor installation area 5. The middle section 8 is located in the housing 101. The middle section 8, the housing 101 and the end plates on both sides thereof enclose a pump cavity. The front cover 102 covers the outside of the synchronous parallel motor 4. The heat of the synchronous parallel motor 4 can be dissipated through the front cover 102. The body 1012 of the housing 101 is provided with a water inlet 10 and a water outlet 11. The two cover plates 1011 are preferably screwed to the body 1012 of the housing 101 for easy disassembly and assembly. The front cover 102 is snap-fitted or interference-fitted with the outer peripheral surface of the housing 101.

[0035] The synchronous parallel motor 4 usually includes a conjoined stator 401, a first rotor 402 and a second rotor 403. The first rotor 402 is fixed outside the first drive shaft 2, and the second rotor 403 is fixed outside the second drive shaft 3. The first drive shaft 2 and the second drive shaft 3 are matched with the conjoined stator 401 at the same time. The rotor and the drive shaft are fixedly connected by interference fit or key connection. The conjoined stator 401 drives the two rotors synchronously, and the two rotors drive the corresponding drive shafts to rotate respectively. There is no distinction between the driving shaft and the driven shaft. Therefore, the structures of the first drive shaft 2 and the second drive shaft 3 are completely consistent, which reduces the requirements for the strength of the drive shaft and improves the synchronization of the two shafts.

[0036] For convenient installation, an installation frame 12 is fixed on the cover plate 1011 surrounding the motor installation area 5. The integral stator 401 is clamped between the installation frame 12 and the front end cover 102. As Figure 3 shown, the installation frame 12 has the same outer contour shape as the integral stator 401 and abuts against the shaft end of the integral stator 401.

[0037] Support bearings: including a first support bearing 13, a second support bearing 14 and a third support bearing 15. The support bearings on the two drive shafts are the same, both including a first support bearing 13, a second support bearing 14 and a third support bearing 15. Here, the first drive shaft 2 is taken as an example, and the structure of the second drive shaft 3 is the same. The left support section 9 of the first drive shaft 2 is supported on the front end cover 102 through the first support bearing 13 and on the installation frame 12 through the second support bearing 14. The right support section 9 of the first drive shaft 2 is supported on the cover plate 1011 surrounding the support area 7 through the third support bearing 15. The first support bearing 13 and the third support bearing 15 connect the two ends of the first drive shaft 2 to provide fixed support for the first drive shaft 2. The second support bearing 14 is on the right side of the first support bearing 13, and the two are separated by the first rotor 402. In addition to playing the role of fixedly supporting the first drive shaft 2 and the second drive shaft 3, the second support bearing 14 further reduces the vibration of the first drive shaft 2 and the second drive shaft 3 during operation from a structural point of view, improves the phase accuracy when the first drive shaft 2 and the second drive shaft 3 rotate, and avoids the blades on the first drive shaft 2 and the second drive shaft 3 from colliding with each other. Since the support bearings only play a supporting role and have low sealing requirements, they are simpler in structure compared with the bearings in the gearbox.

[0038] At the rear end of the vacuum pump, the bearing chamber is located on the cover plate 1011. The rear end cover 102 is a panel-like structure and is fixed to the end face of the cover plate 1011 surrounding the support area 7 by screws, which is convenient for installing the third support bearing 15.

[0039] In order to adapt to the rotor diameter, the front end of the drive shaft has a smaller diameter, which is convenient for connecting with the rotor; the middle part of the drive shaft is located in the pump chamber and has a larger diameter to ensure that the drive shaft has a certain mechanical strength during operation; the rear end of the drive shaft has a smaller diameter to adapt to the bearing diameter at the rear end cover 102. That is, the diameter of the support section 9 is smaller than the diameter of the middle section 8. In further design, in order to facilitate the assembly of the bearings and axially limit the bearings, the support section 9 includes a bearing installation section 901 and a limit section 902. The limit section 902 is located between the bearing installation section 901 and the middle section 8. The diameters of the middle section 8, the limit section 902 and the bearing installation section 901 decrease in sequence. The support bearing is assembled on the bearing installation section 901, and the limit section 902 axially limits the support bearing.

[0040] Installation process: Install the second support bearing 14 at the front end of the first drive shaft 2, and install the first rotor 402 in an interference fit or key connection manner. The first rotor 402 is on the left side of the second support bearing 14, and install the first rotor 402 into the integral stator 401; Install another second support bearing 14 at the front end of the second drive shaft 3, and install the second rotor 403 in an interference fit or key connection manner. The second rotor 403 is on the left side of the second support bearing 14, and install the second rotor 403 into the integral stator 401. Two first support bearings 13 are on the front end cover 102, and two third support bearings 15 are on the rear end cover 102. Install the front end cover 102 and the rear end cover 102, so that the two first support bearings 13 are respectively installed at the front ends of the first drive shaft 2 and the second drive shaft 3, and the two third support bearings 15 are respectively installed at the rear ends of the first drive shaft 2 and the second drive shaft 3; Finally, install the housing 101.

[0041] Figure 3 It is to Figure 1 The three-dimensional view of the new structure Roots pump after removing the front end cover 102. It can be more intuitively found from Figure 3 that for the double-rotor Roots vacuum pump proposed by the present utility model, a synchronous parallel motor 4 is installed on the front mounting bracket, and the integral stator 401 directly drives the double shafts to work without passing through gear transmission. Therefore, the double-shaft synchronism is better, and the efficiency of direct drive is also higher. It is not only applicable to Roots pumps, but also applicable to application scenarios with high requirements for double-shaft synchronism, such as twin-screw compressors, twin-screw extruders, etc.

[0042] From Figure 3 and Figure 4 it can be seen that the new structure Roots vacuum pump has a simpler structure, is simple in processing and assembly, cancels the gears and gearbox, eliminates the risk of oil leakage, directly drives the double shafts by the integral motor, has better double-shaft synchronism, eliminates the energy loss during gear transmission, improves the operation efficiency, and has the same requirements for the double shafts.

[0043] In summary, for the double-rotor Roots vacuum pump proposed by the present utility model, the pump and the motor are of an integral structure, and the synchronous parallel motor 4 is used to directly drive the two drive shafts without the need for gearbox transmission. Therefore:

[0044] 1) There is no need for gear transmission, there is no risk of oil leakage during operation, there is no need to stop regularly to add lubricating oil, the continuous working ability is increased, and equipment maintenance is reduced. 2) The volume of the new structure Roots pump is smaller than that of the traditional Roots pump; 3) Direct drive, high working efficiency, good double-shaft synchronism; 4) Simple structure, convenient for processing, installation and disassembly; 5) Without a gearbox, the bearing sealing requirements are reduced, and the cost is reduced; 6) The pump and the motor are of an integral structure, improving the dynamic sealing performance of the Roots pump. 7) The motor is located at one end of the pump cavity. Compared with the embedded motor, the heat dissipation effect is better, and it is convenient for disassembly and maintenance.

[0045] In the description of the present utility model, it should be understood that the orientation or positional relationship indicated by terms such as "center", "front", "rear", "left", "right", "inner", "outer", "axial", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present utility model.

[0046] In addition, terms such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0047] In this specification, the schematic expression of the above terms does not necessarily refer to the same embodiment. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments.

[0048] Based on the above inspiration from the ideal embodiments of the present utility model, through the above description, relevant staff can completely make various changes and modifications without departing from the technical idea of the present utility model. The technical scope of the present utility model is not limited to the content in the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A two-rotor Roots vacuum pump, characterized in that: It comprises a housing assembly (1), and a first drive shaft (2), a second drive shaft (3) and a synchronous parallel motor (4) located inside the housing assembly (1); The housing assembly (1) comprises a motor installation area (5), a working area (6) and a support area (7) which are axially connected to each other. The first drive shaft (2) and the second drive shaft (3) both comprise an intermediate section (8) and support sections (9) located at both ends of the intermediate section (8). The intermediate section (8) and the working area (6) form a pump cavity. One of the support sections (9) of the two drive shafts is assembled in the motor installation area (5) in cooperation with the synchronous parallel motor (4), and the other support section (9) is assembled in the support area (7). The two support sections (9) of the two drive shafts are fixedly supported by support bearings.

2. The twin-rotor Roots vacuum pump according to claim 1, wherein: The housing assembly (1) comprises a shell (101) and a front cover (102) and a rear cover (103) located at both ends of the shell (101); both ends of the shell (101) have cover plates (1011); the two cover plates (1011) separate the housing assembly (1) into a motor installation area (5), a working area (6) and a support area (7); the first drive shaft (2) and the second drive shaft (3) both pass through the two cover plates (1011); the front cover (102) and the shell (101) enclose the motor installation area (5).

3. The twin-rotor Roots vacuum pump according to claim 2, characterized in that: The synchronous parallel motor (4) comprises a conjoined stator (401), a first rotor (402) and a second rotor (403); the first rotor (402) is fixed outside the first drive shaft (2), the second rotor (403) is fixed outside the second drive shaft (3), and the first drive shaft (2) and the second drive shaft (3) are simultaneously matched with the conjoined stator (401).

4. The twin-rotor Roots vacuum pump according to claim 2, characterized in that: A water inlet (10) and a water outlet (11) are provided on the body (1012) of the housing (101), and two cover plates (1011) are fixed to the body (1012) of the housing (101) by screws.

5. The two-stage roots vacuum pump according to claim 2, wherein: The front end cover (102) is snap-fitted or interference-fitted with the outer peripheral surface of the housing (101).

6. The roots vacuum pump with double rotors according to claim 3, characterized in that: A mounting frame (12) is fixed on the cover plate (1011) that encloses the motor mounting area (5), and the connected stator (401) is clamped between the mounting frame (12) and the front end cover (102).

7. The twin-rotor Roots vacuum pump according to claim 6, characterized in that: The support bearings include a first support bearing (13), a second support bearing (14) and a third support bearing (15); one end support section (9) of the two drive shafts is supported on the front end cover (102) through the first support bearing (13), and is supported on the mounting frame (12) through the second support bearing (14); the other end support section (9) of the two drive shafts is supported on a cover plate (1011) that encloses the support area (7) through the third support bearing (15).

8. The roots vacuum pump with double rotors according to claim 7, characterized in that: The rear end cover (103) is fixed to the end surface of the cover plate (1011) surrounding the support area (7) by means of screws.

9. The roots vacuum pump with double rotors according to claim 1, characterized in that: The diameter of the supporting section (9) is smaller than the diameter of the middle section (8).

10. The twin-rotor Roots vacuum pump according to claim 1, characterized in that: The support section (9) includes a bearing mounting section (901) and a limiting section (902). The limiting section (902) is located between the bearing mounting section (901) and the intermediate section (8). The diameters of the intermediate section (8), the limiting section (902), and the bearing mounting section (901) decrease in sequence. A support bearing is assembled on the bearing mounting section (901), and the limiting section (902) axially limits the support bearing.

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