Two-stage composite vacuum pump device

Abstract

The utility model relates to a two-stage composite vacuum pump device which is of a two-stage structure formed by connecting a screw vacuum pump unit and a roots vacuum pump unit in series, each stage of vacuum pump unit is provided with an independent pump cavity, the front stage of vacuum pump unit is a screw rotor, and the rear stage of vacuum pump unit is a roots rotor. An air suction port of the front-stage screw vacuum pump is directly connected with an air exhaust port of the rear-stage roots vacuum pump through an air channel arranged in a partition cavity at the bottom of a partition plate in the pump body, and the screw rotors and the roots rotors enable two pairs of rotors in the pump body to be meshed with each other at a certain gap and rotate synchronously in the pump body through a pair of synchronous gears in a gear box at the end of the pump body. The device is simpler in structure, less in occupied space and field, lower in operation energy consumption, convenient to maintain and lower in use cost.

Description

Technical Field

[0001] The utility model relates to the technical field of vacuum equipment, in particular to a two-stage compound vacuum pump device. Background Art

[0002] At present, various vacuum equipment with high energy consumption and high pollution emissions are still widely used in many vacuum application fields, including oil-sealed vacuum pumps such as rotary vane vacuum pumps and sliding valve vacuum pumps that consume a lot of oil and emit waste gas, as well as liquid ring vacuum pumps, steam jet pumps, water jet vacuum pumps or vacuum units that consume a lot of energy and emit a large amount of waste liquid and waste gas. These vacuum pumps and vacuum units can no longer meet the requirements of energy conservation, environmental protection and low emissions.

[0003] Traditional vacuum units combining Roots vacuum pumps and screw vacuum pumps are connected via flexible piping and instrument valves. This increases their size, occupies a large footprint, consumes high operating energy, and is difficult to maintain. Conventional screw vacuum pumps are limited in the vacuum levels they can achieve. To meet higher vacuum requirements, existing technology uses connecting pipes and external coolers to connect a standard Roots vacuum pump in series with a screw vacuum pump via pipe valves. This two-stage Roots screw vacuum pump unit requires two motors and two sets of cooling equipment. This type of two-stage Roots screw vacuum pump unit suffers from complex structure and bulk, as well as complex control and a high failure rate.

[0004] Based on the above problems, the applicant proposes a two-stage compound vacuum pump device, which is oil-free, has no waste gas, no waste liquid emissions, and is energy-saving and environmentally friendly. Summary of the Invention

[0005] The purpose of the utility model is to overcome the above-mentioned shortcomings and provide a two-stage compound vacuum pump device with a simple structure, energy saving and environmental protection, less space and site occupation, lower operating energy consumption and easy maintenance.

[0006] The purpose of this utility model is achieved in this way:

[0007] A two-stage compound vacuum pump device comprises a pump body, wherein the front end of the pump body is provided with a front end cover, and the rear end is provided with a rear end cover. The pump body is provided with a dual-shaft dual-stage structure, wherein the dual-shaft dual-stage structure comprises a front-stage screw vacuum pump cavity, a rear-stage Roots vacuum pump cavity, and a pair of transmission shafts. A partition is provided between the front-stage screw vacuum pump cavity and the rear-stage Roots vacuum pump cavity, and the partition is provided with a through hole for the two transmission shafts to pass through; the two transmission shafts are arranged horizontally and in parallel, and are respectively a driving shaft and a driven shaft;

[0008] An air inlet is provided at the top of the rear-stage Roots vacuum pump cavity, an air suction cavity is provided below the air inlet, and the air suction cavity is connected to the air suction channel. An exhaust port is provided at the bottom of the front-stage screw vacuum pump cavity, an exhaust cavity is provided above the exhaust port, and the exhaust cavity is connected to the exhaust channel. The exhaust channel is connected to the air suction channel, so that the front-stage screw vacuum pump cavity and the rear-stage Roots vacuum pump cavity are connected;

[0009] A pair of screw rotors are provided in the cavity of the front-stage screw vacuum pump, and the screw rotors are sleeved on the transmission shaft. A front end cover is provided at the front end of the cavity of the front-stage screw vacuum pump, and an oil tank is provided on the front end cover. A pair of Roots rotors are provided in the cavity of the rear-stage Roots vacuum pump, and a rear end cover is provided at the rear end of the cavity of the rear-stage Roots vacuum pump, and a gear box is provided on the rear end cover. A pair of synchronous gears are provided in the gear box, and the synchronous gears are sleeved on the end of the driving shaft.

[0010] The front end of the driving shaft extends out of the oil tank and is connected to a coupling. The coupling is connected to the motor. The power of the motor is transmitted to the driving shaft through the coupling, and then transmitted to the driven shaft through the synchronous gear.

[0011] Furthermore, a cooling jacket is respectively provided on the outside of the front-stage screw vacuum pump cavity and the rear-stage Roots vacuum pump cavity, and a coolant is provided in the cooling jacket for cooling.

[0012] Furthermore, the screw rotor is a variable pitch screw rotor, and the screw axial direction of the screw rotor is a variable pitch distribution.

[0013] Furthermore, the Roots rotor is a three-lobed rotor, and its end face profile adopts a three-lobed involute and circular arc combined profile structure.

[0014] Furthermore, both ends of the driving shaft are supported in the front and rear ends of the pump body through bearings.

[0015] Furthermore, a mechanical seal is provided between the oil tank and the driving shaft to isolate the vacuum pump from the atmosphere at the extended end of the main shaft, and the mechanical seal is a balanced mechanical seal.

[0016] Furthermore, the air inlet of the pump body is connected to the vacuum container, and the air outlet is connected to a muffler.

[0017] Furthermore, the screw rotor and the Roots rotor are connected in series on two transmission shafts at a certain pumping volume ratio.

[0018] Furthermore, a certain gap is maintained between the screw rotor and the Roots rotor curved surface, between the rotor outer circle and the inner hole of the vacuum pump chamber, and between the rotor end face and the end cover plane. The gap is determined by the pumping speed specification, compression ratio and thermal expansion size of the pump.

[0019] Furthermore, the motor is arranged on a machine base, and a muffler is arranged inside the machine base.

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] The utility model provides a two-stage compound vacuum pump device, including a double-shaft two-stage structure, a pair of variable-pitch screw rotors are provided in the front stage, and a pair of three-leaf Roots rotors are provided in the rear stage. The screw rotors and the Roots rotors operate with a certain meshing gap in the pump chamber, and no lubricating oil is required in the pump chamber. Therefore, the utility model is an oil-free high vacuum pump and can replace a Roots rotary vane vacuum unit, a Roots slide valve vacuum unit, and a Roots liquid ring vacuum unit.

[0022] The utility model combines a first-stage Roots vacuum pump and a first-stage screw vacuum pump in one vacuum pump. The volume ratio of the front and rear stages of the pump is allocated according to a certain ratio. This ratio can reduce the compression ratio between the two-stage vacuum pumps, thereby reducing the temperature rise and power consumption of the vacuum pump, saving electricity and water and enabling the vacuum pump to operate well within the lowest possible temperature range. In addition, energy consumption and equipment footprint are saved by more than 30% compared with the above-mentioned vacuum unit, and zero emission of waste gas and wastewater can be achieved, thereby saving energy and being environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural diagram of the present utility model.

[0024] Figure 2 It is a cross-sectional schematic diagram of the double-axis double-stage structure of the utility model.

[0025] Figure 3 This is a schematic diagram of the end face meshing of the front-stage screw rotor of the present invention.

[0026] Figure 4 This is a schematic diagram of the end face engagement of the rear-stage Roots rotor of the present invention.

[0027] in:

[0028] Pump body 1, air inlet 1.1, exhaust port 1.2, suction chamber 1.3, suction duct 1.4, exhaust chamber 1.5, exhaust duct 1.6, cooling sleeve 1.7, front cover 2, oil tank 3, coupling 4, rear cover 5, gearbox 6, synchronous gear 7, screw rotor 8, Roots rotor 9, mechanical seal 10, motor 11, base 12, muffler 13. DETAILED DESCRIPTION

[0029] To better understand the technical solution of the present invention, the following detailed description is provided with reference to the relevant illustrations. It should be understood that the following specific embodiments are not intended to limit the specific implementation of the technical solution of the present invention; they are merely examples of possible implementations of the technical solution of the present invention. It should be noted that the description herein of the positional relationships of the various components, such as component A being located above component B, is based on the relative positions of the components in the illustrations and is not intended to limit the actual positional relationships of the components. Example 1

[0030] See also Figures 1-4 , Figure 1 A schematic diagram of the structure of the present invention is drawn. As shown in the figure, a two-stage compound vacuum pump device includes a pump body 1, the front end of the pump body 1 is provided with a front cover 2, and the rear end is provided with a rear cover 5. The pump body 1 is provided with a dual-shaft dual-stage structure. The dual-shaft dual-stage structure includes a front-stage screw vacuum pump cavity, a rear-stage Roots vacuum pump cavity, and a pair of transmission shafts. The front-stage screw vacuum pump cavity and the rear-stage Roots vacuum pump cavity are separated by a partition, and the partition is provided with a through hole for the penetration of the two transmission shafts; the two transmission shafts are arranged horizontally and parallel, and are respectively a driving shaft and a driven shaft, and the driving shaft and the driven shaft rotate in opposite directions.

[0031] An air inlet 1.1 is provided at the top of the rear-stage Roots vacuum pump cavity, and an air suction chamber 1.3 is provided below the air inlet 1.1. The air suction chamber 1.3 is connected to an air suction channel 1.4. An exhaust port 1.2 is provided at the bottom of the front-stage screw vacuum pump cavity, and an exhaust chamber 1.5 is provided above the exhaust port 1.2. The exhaust chamber 1.5 is connected to an exhaust channel 1.6. The exhaust channel 1.6 is connected to the air suction channel 1.4, so that the front-stage screw vacuum pump cavity and the rear-stage Roots vacuum pump cavity are connected.

[0032] A cooling jacket 1.7 is provided on the outside of the front-stage screw vacuum pump cavity and the back-stage Roots vacuum pump cavity respectively. Cooling liquid is provided in the cooling jacket 1.7 for cooling.

[0033] A pair of screw rotors 8 are provided in the cavity of the front-stage screw vacuum pump. The screw rotors 8 are variable-pitch screw rotors, whose end profiles are composed of involutes and circular arcs, and the screw axial direction of the screw rotors 8 is variable-pitch. The screw rotors 8 are sleeved on the transmission shaft. A front end cover 2 is provided at the front end of the cavity of the front-stage screw vacuum pump, and an oil tank 3 is provided on the front end cover 2.

[0034] The rear-stage Roots vacuum pump cavity is provided with a pair of Roots rotors 9, each of which is a three-lobed rotor, and its end profile adopts a three-lobed involute and circular arc combined profile structure. The rear end of the rear-stage Roots vacuum pump cavity is provided with a rear end cover 5, and a gear box 6 is provided on the rear end cover 5;

[0035] Both ends of the driving shaft are supported in the front cover 2 and the rear cover 5 at the front and rear ends of the pump body 1 through bearings.

[0036] A pair of synchronous gears 7 are provided in the gear box 6. The synchronous gears 7 are sleeved on the end of the driving shaft to ensure uniform meshing, suction and exhaust of the two pairs of rotors in the compound vacuum pump.

[0037] The front end (outgoing shaft end) of the driving shaft extends out of the oil tank 3 and is connected to the coupling 4. The coupling 4 is connected to the motor 11. The motor 11 is set on the machine base 12. The power of the motor 11 is transmitted to the driving shaft through the coupling 4, and then transmitted to the driven shaft through the synchronous gear 7.

[0038] A mechanical seal 10 is provided between the oil tank 3 and the driving shaft to isolate the vacuum pump from the atmosphere at the extended end of the main shaft. The mechanical seal 10 is a balanced mechanical seal.

[0039] The air inlet 1.1 of the pump body 1 is connected to the vacuum container, and the exhaust port 1.2 is connected to the muffler 13. The gas discharged by the pump is discharged into the atmosphere through the muffler 13, which can reduce the exhaust noise of the pump and reduce environmental pollution.

[0040] The screw rotor 8 and the Roots rotor 9 are connected in series on two transmission shafts at a certain pumping volume ratio. A certain gap is maintained between the curved surfaces of the screw rotor 8 and the Roots rotor 9, between the outer circle of the rotor and the inner hole of the vacuum pump cavity, and between the end face of the rotor and the plane of the end cover. The gap is determined by the pumping speed specification, compression ratio and thermal expansion size of the pump. Therefore, no lubricant is required during the operation of the rotor, and the vacuum pump cavity is an oil-free structure.

[0041] Working principle:

[0042] The utility model provides a two-stage compound vacuum pump device, which is a high vacuum pump composed of a front-stage screw vacuum pump and a rear-stage Roots vacuum pump connected in series in a same pump cavity with a certain volume ratio (i.e., a pumping speed ratio); the air intake of the front-stage screw vacuum pump and the exhaust port of the rear-stage Roots vacuum pump are directly connected through an air channel arranged in a compartment at the bottom of a partition plate in a pump body; the exhaust port of the front-stage screw vacuum pump is connected to a muffler, and the gas is discharged to the atmosphere after being subjected to a sound attenuation treatment; the air inlet of the rear-stage Roots vacuum pump is connected to a vacuum system to be evacuated; cooling water compartments are arranged on the outside of the pump body for cooling the heat generated by the compound vacuum pump due to compressed gas.

[0043] A pair of Roots rotors is located within the Roots vacuum pump, while a pair of screw rotors is located within the screw vacuum pump. The screw and Roots rotors share a common main shaft and are mounted on a pair of horizontal, parallel drive shafts. A pair of synchronous gears in a gearbox at the end of the pump body allow the two pairs of rotors to mesh with each other with a certain clearance and rotate synchronously. The synchronous gears drive the Roots and screw rotors to rotate at constant and opposite speeds within the pump body. The intake and outlet ports of the screw pump are connected via an airway at the bottom of the pump body, forming a two-stage pump system in series. A cooling water barrier is located within each pump stage to cool the exhaust gas. Some of the cooled gas is then recirculated into the subsequent pump stage to cool the rotors and pump body. The front and rear pump stages of this compound vacuum pump are independent of each other. The front stage contains a screw rotor, while the rear stage contains a Roots rotor. The pumping speeds of the front and rear pumps must be proportionally distributed to ensure that the two pumps operate at a specific compression ratio and avoid overheating or overload.

[0044] The front-stage screw rotor adopts a variable pitch screw rotor, and its end profile is composed of an involute and a circular arc. The end profile of the rear-stage Roots rotor adopts a three-leaf involute and circular arc combined profile structure. The Roots rotor and the screw rotor profile have the advantages of good meshing, high volume utilization, high processing precision, small pump reflux, high pumping efficiency and high vacuum degree.

[0045] The screw rotor and Roots rotor are fixed on the main and driven shafts respectively, which rotate in opposite directions. A pair of synchronous gears in the gear box at one end of the pump body ensures the uniform meshing and suction and exhaust of the two pairs of rotors in the compound vacuum pump.

[0046] Water cooling jackets are provided on the outside of the Roots vacuum pump cavity and the screw vacuum pump cavity. The cooling water jackets at the pump cavity outer shell are filled with cooling water, so that the vacuum pump does not need to be equipped with additional cooling devices during operation.

[0047] This utility model arranges a first-stage Roots vacuum pump and a first-stage screw vacuum pump within the same pump body, within two chambers. The two vacuum pumps are connected in series via a partition within the pump body, connecting the suction port of the first stage to the exhaust port of the next stage. The vacuum pump's cooling system is also located directly within the pump body's internal jacket, eliminating the need for complex gas and cooling water piping connections and simplifying the control system. Consequently, the compound vacuum pump boasts a very compact structure, and direct cooling provides a more effective cooling effect than external cooling. The two vacuum pumps share a common motor and cooling device, resulting in a compact structure, small size, low energy consumption, and ease of installation.

[0048] The utility model can achieve a high vacuum of more than 0.1 Pa. The vacuum pump can be widely used in high vacuum application fields such as microelectronics, lithium batteries, solar energy, chemical industry, pharmaceuticals, food, vacuum coating, etc.

[0049] The above are only specific application examples of the present invention and do not constitute any limitation on the scope of protection of the present invention. Any technical solution formed by equivalent transformation or equivalent replacement shall fall within the scope of protection of the present invention.

Claims

1. A two-stage compound vacuum pump device, characterized in that: It comprises a pump body (1), wherein the front end of the pump body (1) is provided with a front cover (2), and the rear end is provided with a rear cover (5), wherein a double-shaft double-stage structure is provided in the pump body (1), and the double-shaft double-stage structure comprises a front-stage screw vacuum pump cavity, a rear-stage Roots vacuum pump cavity and a pair of transmission shafts, wherein a partition is provided between the front-stage screw vacuum pump cavity and the rear-stage Roots vacuum pump cavity, and a through hole is provided on the partition for the two transmission shafts to pass through; the two transmission shafts are arranged horizontally and in parallel, and are respectively a driving shaft and a driven shaft; An air inlet (1.1) is provided at the top of the rear-stage Roots vacuum pump cavity, an air suction cavity (1.3) is located below the air inlet (1.1), and the air suction cavity (1.3) is connected to an air suction channel (1.4); an exhaust port (1.2) is provided at the bottom of the front-stage screw vacuum pump cavity, an exhaust cavity (1.5) is located above the exhaust port (1.2), and the exhaust cavity (1.5) is connected to an exhaust channel (1.6), and the exhaust channel (1.6) is connected to the air suction channel (1.4), so that the front-stage screw vacuum pump cavity and the rear-stage Roots vacuum pump cavity are connected; A pair of screw rotors (8) are provided in the front-stage screw vacuum pump cavity, and the screw rotors (8) are sleeved on the transmission shaft. A front end cover (2) is provided at the front end of the front-stage screw vacuum pump cavity, and an oil tank (3) is provided on the front end cover (2); a pair of Roots rotors (9) are provided in the rear-stage Roots vacuum pump cavity, and a rear end cover (5) is provided at the rear end of the rear-stage Roots vacuum pump cavity, and a gear box (6) is provided on the rear end cover (5); a pair of synchronous gears (7) are provided in the gear box (6), and the synchronous gears (7) are sleeved on the end of the driving shaft; The front end of the driving shaft extends out of the oil tank (3) and is connected to the coupling (4). The coupling (4) is connected to the motor (11). The power of the motor (11) is transmitted to the driving shaft through the coupling (4), and then transmitted to the driven shaft through the synchronous gear (7).

2. A two-stage compound vacuum pump device according to claim 1, characterized in that: A cooling jacket (1.7) is provided on the outside of the front-stage screw vacuum pump cavity and the rear-stage Roots vacuum pump cavity, respectively. Cooling liquid is provided in the cooling jacket (1.7) for cooling.

3. A two-stage compound vacuum pump device according to claim 1, characterized in that: The screw rotor (8) adopts a variable pitch screw rotor, and the screw axial direction of the screw rotor (8) is distributed with a variable pitch.

4. A two-stage compound vacuum pump device according to claim 1, characterized in that: The Roots rotor (9) is a three-lobed rotor, and its end face profile adopts a three-lobed involute and circular arc combined profile structure.

5. The two-stage compound vacuum pump device according to claim 1, characterized in that: Both ends of the driving shaft are supported by bearings in the front end cover (2) and the rear end cover (5) at the front and rear ends of the pump body (1).

6. A two-stage compound vacuum pump device according to claim 1, characterized in that: A mechanical seal (10) is provided between the oil tank (3) and the driving shaft.

7. The two-stage compound vacuum pump device according to claim 1, characterized in that: The air inlet (1.1) of the pump body (1) is connected to the vacuum container, and the air outlet (1.2) is connected to the muffler (13).

8. The two-stage compound vacuum pump device according to claim 1, characterized in that: The screw rotor (8) and the Roots rotor (9) are connected in series on two transmission shafts at a certain suction volume ratio.

9. The two-stage compound vacuum pump device according to claim 1, characterized in that: A certain gap is maintained between the curved surfaces of the screw rotor (8) and the Roots rotor (9), between the outer circle of the rotor and the inner hole of the vacuum pump cavity, and between the end face of the rotor and the plane of the end cover. The gap is determined according to the pumping speed specification, compression ratio and thermal expansion size of the pump.

10. The two-stage compound vacuum pump device according to claim 1, characterized in that: The motor (11) is arranged on a machine base (12), and a muffler (13) is arranged in the machine base (12).

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