CN111720328A - Multi-stage vacuum pump sharing drive shaft - Google Patents

Abstract

The invention discloses a multi-stage vacuum pump with a shared driving shaft, which comprises a plurality of vacuum driving cavities which are connected in series or in parallel to form the multi-stage vacuum driving cavities, wherein at least one rotor is arranged in each independent vacuum driving cavity, the inlet of the first stage vacuum driving cavity is communicated with the atmosphere, at least two vacuum driving cavities are driven by the shared driving shaft, and the shared driving shaft comprises at least two separated driving shafts. The vacuum pump composed of the plurality of vacuum driving cavities can be a coaxial multi-stage pump, such as a multi-stage roots pump, driven by a single motor, or at least one non-coaxial vacuum driving cavity is driven by an independent or shared driving motor. Due to the adoption of the sectional type driving shaft, expansion and contraction of heat and cold of a pair of impellers and the shaft in each vacuum cavity cannot be transmitted to the other vacuum cavity adjacent to the axial direction, and the influence of expansion and contraction of heat and cold of the adjacent cavity in the axial direction cannot be caused.

Description

Multi-stage vacuum pump sharing drive shaft

Technical Field

The present invention relates to the field of vacuum pumps, and in particular to a multi-stage vacuum pump comprising at least one common drive shaft.

Background

In the field of vacuum technology, the equipments capable of directly exhausting air and forming vacuum mainly include liquid ring pumps, direct exhaust air-cooled roots vacuum pumps, ejector pumps (including steam ejector pumps, water ejector pumps), slide valve pumps, reciprocating pumps, rotary vane vacuum pumps (divided into oil-type rotary vane vacuum pumps and oil-free dry rotary vane vacuum pumps), screw vacuum pumps, claw vacuum pumps, multistage roots vacuum pumps, scroll vacuum pumps, etc. The common roots vacuum pump can form higher vacuum, but the exhaust pressure cannot reach the pressure of direct exhaust atmosphere, and the vacuum pump is required to be equipped as a backing pump to ensure that the pump can normally and safely operate. The roots type air cooling pump can directly discharge air, but the efficiency is reduced, the power consumption and the noise are large because the exhausted air must be led back to the pump cavity after being cooled, and the maximum working vacuum degree is only about 2 ten thousand pascals.

From the perspective of energy conservation, emission reduction and environmental protection, the dry pump is a big trend of future development. However, although dry vacuum pumps do not produce a large amount of waste water and waste oil, which is much less environmentally friendly than non-dry vacuum pumps, the various types of dry vacuum pumps on the market have a number of inherent disadvantages, which restrict their wider use. In order to solve the problems related to the vacuum pump in the prior art, the inventor provides a multi-drive-cavity non-coaxial vacuum pump, which comprises a plurality of independent vacuum drive cavities, wherein the plurality of vacuum drive cavities are connected in series to form a multi-stage vacuum drive cavity, and each independent vacuum drive cavity is internally provided with a pair of independent rotors, and the multi-drive-cavity non-coaxial vacuum pump is characterized in that the main flow direction of air flow of the plurality of vacuum drive cavities and a rotor drive shaft form a vertical or 30-90-degree large included angle, an inlet of a first-stage vacuum drive cavity is communicated with the atmosphere, all or part of the plurality of vacuum drive cavities are not coaxial, all the non-coaxial vacuum cavities are driven by independent drive motors, the plurality of vacuum drive cavities are sequentially stacked into the multi-stage vacuum drive cavities connected in series from top to bottom, a suction inlet of a next-stage vacuum drive cavity is connected with an exhaust port of a previous-stage, the exhaust port is located below, the two sides of the vacuum driving cavity are respectively provided with a cooling water cavity, and a jacket water layer is arranged below each vacuum driving cavity.

However, although the vacuum pump in the above prior art can solve some problems in terms of environmental protection, when the multi-stage vacuum driving chambers use a common driving shaft, the impeller/shaft in each vacuum chamber may expand or contract due to the expansion and contraction of the adjacent vacuum chambers.

Therefore, in order to improve the above problems, the inventor of the present invention proposed the present invention such that the common drive shaft of the multi-stage vacuum pump can transmit the torque force, and the axial influence of the drive shaft of one vacuum drive chamber on the drive shaft of the other connected vacuum drive chamber caused by thermal expansion and contraction can be eliminated.

Disclosure of Invention

The invention aims to provide a multi-stage vacuum pump comprising at least one common driving shaft, wherein the multi-stage vacuum pump is a dry vacuum pump which can bear certain dust and certain corrosion, is convenient to maintain and has large pumping capacity.

According to the preferred embodiment of the scheme, the plurality of vacuum driving cavities are sequentially stacked into the multistage vacuum driving cavities connected in series from top to bottom, the suction inlet of the lower vacuum driving cavity is connected with the exhaust outlet of the upper vacuum driving cavity, the suction inlet of each vacuum driving cavity is located above, the exhaust outlet is located below or on the side, and each vacuum driving cavity is driven by the independent motor.

In order to achieve the above object, the present invention provides a multi-stage vacuum pump including at least one common driving shaft, comprising a plurality of independent vacuum driving chambers, wherein the plurality of vacuum driving chambers are connected in series or in parallel to form a multi-stage vacuum driving chamber, at least one rotor is arranged in each independent vacuum driving chamber, and an inlet of a first stage vacuum driving chamber is directly communicated with the atmosphere or a foreline device; wherein at least two vacuum drive chambers are driven by a common drive shaft, wherein the common drive shaft comprises at least two separate drive shafts.

Preferably, the at least two vacuum driving chambers driven by the common driving shaft are a first vacuum driving chamber and a second vacuum driving chamber respectively, the common driving shaft includes a first separation driving shaft and a second separation driving shaft, the first separation driving shaft is located in the first vacuum driving chamber, the second separation driving shaft is located in the second vacuum driving chamber, wherein the first separation driving shaft and the second separation driving shaft are connected by a first connecting member, and the first separation driving shaft and the second separation driving shaft are spaced apart by a distance.

It is further preferred that the common drive shaft further comprises a third split drive shaft, the first split drive shaft being located on one side of the second split drive shaft and the third split drive shaft being located on the other side of the second split drive shaft, the second split drive shaft being connected to the third split drive shaft by a second connection.

It is further preferred that the third separating drive shaft is connected to the motor shaft of a drive motor.

Further preferably, the first vacuum driving chamber further comprises a first driven shaft, and the first driven shaft is connected with a first gear; wherein the first split drive shaft is connected with a second gear; the first gear engages the second gear.

Further preferably, the second vacuum driving chamber further comprises a second driven shaft, and the second driven shaft is connected with a third gear; wherein the second split drive shaft is connected with a fourth gear; the third gear engages the fourth gear.

Preferably, the vacuum pump comprising a plurality of the vacuum driving chambers is a coaxial multi-stage pump.

Further preferably, the vacuum pump is a multistage roots pump or a screw vacuum pump or a multistage claw vacuum pump.

Preferably, the vacuum pump is a non-coaxial multi-stage vacuum pump having at least one coaxial line.

In practical applications, the multi-stage vacuum chambers that may be selected by the present invention may be 2, 3, 4, 5, 6 or even more stages, depending on practical requirements. The driving motors may share power through a transmission device, or the motors may correspond to the vacuum chambers in number one by one.

According to the preferred embodiment of the invention, the vacuum driving cavity is designed by a roots pump, and the vacuum driving cavity can be driven by a fixed-frequency or variable-frequency driving motor, namely a rotor driving shaft of the vacuum driving cavity is connected with the fixed-frequency or variable-frequency driving motor.

Drawings

Fig. 1 is a schematic diagram of the present invention.

Fig. 2 is a schematic structural view of a partially coaxial embodiment of the present invention.

Fig. 2-1 is another embodiment of fig. 2.

FIG. 3 is a cross-sectional view of a coaxial vacuum drive chamber.

Fig. 4 is a schematic structural view of another partially coaxial embodiment of the present invention.

Fig. 5 is a cross-sectional view of fig. 4.

Fig. 5-1 is another embodiment of fig. 5.

Detailed Description

The multi-stage vacuum pump including at least one common driving shaft also adopts multi-stage compression, and the principle is that a plurality of independent vacuum driving cavities (the number of vacuum driving cavity modules is determined according to actual needs) are arranged in the vacuum pump cavity, and each independent vacuum chamber is provided with a pair of independent Roots rotors. Referring to fig. 1, in this embodiment, four vacuum driving chambers are included, namely a 1-stage vacuum driving chamber 1, a 2-stage vacuum driving chamber 2, a 3-stage vacuum driving chamber 3 and a 4-stage vacuum driving chamber 4, and the principle is as follows: when the non-coaxial vacuum pump suction inlet 5 of many drive chamber bodies reaches 1 mbar's limit vacuum, the gas vent is 20mbar, the compression ratio is approximately 20 times, the gas vent in 2 grades of vacuum drive chamber is 120mbar, the compression ratio is approximately about 6 times, the gas vent in 3 grades of vacuum drive chamber is 360mbar, the compression ratio is approximately about 3 times, the gas vent 6 in 4 grades of vacuum drive chamber is 1080mbar, the compression ratio is also approximately about 3 times, in the actual project, then according to different demands, design independent pump chamber, realize different compression ratios.

When the inlet is loaded, the vacuum level at the suction port is below 1mbar and the compression ratio of each adjacent vacuum driven chamber is correspondingly reduced (the overall compression ratio is reduced).

The compression ratio is mainly based on the heat and the consumed power that each vacuum driving cavity can bear, and the higher the vacuum environment, the higher the compression ratio is, but the mass flow of the compressed gas is lower (under the same volume), the accumulated heat is lower (mainly affected by heat dissipation), and the consumed power is also lower, so the compression ratio can be larger at the moment. In a rough vacuum environment, the mass flow rate of the compressed gas is high (under the same volume), the accumulated heat is large (the heat dissipation effect is small), and the consumed power is large, so that the compression ratio is required to be as small as possible.

In view of the schematic diagram of the apparatus, the rotation direction of the rotor of the stage 1 vacuum driving chamber of the variable speed variable capacity dry vacuum pump of this embodiment is the same as the rotation direction of the rotor of the stage 3 vacuum driving chamber (the driving shafts of the stage 1 and the stage 3 vacuum driving chambers are the same axis), but is the same as the rotation direction of the rotor of the stage 2 vacuum driving chamber and the stage 4 vacuum driving chamber (the driving shafts of the stage 2 and the stage 4 vacuum driving chambers are the same axis), so the driving shafts of the four vacuum driving chambers are not on the same axis, which is completely different from the conventional multistage roots vacuum pump, claw vacuum pump, and screw vacuum pump.

In order to further optimize the operation effect, the invention also provides a frequency conversion driving mode of individual or all vacuum driving chambers, which optimizes all aspects including but not limited to compression ratio, motor, heat management and the like by frequency conversion control at any time according to specific requirements of time, pressure, pumping speed, temperature and the like. These characteristics are not realized by a coaxial multistage roots pump, a screw pump and a claw pump.

What has been described above is the technical principle of the present invention, namely, a continuously variable compression variable-speed variable-capacity dry vacuum pump with multiple driving cavities that are not coaxial or are not completely coaxial.

FIG. 2 is an external view of a second embodiment of a multi-drive chamber non-coaxial vacuum pump, and FIG. 3 is a cross-sectional view of FIG. 2. In the figure: 1 is 1 level vacuum drive chamber, 3 is 3 level vacuum drive chambers, 5 is the vacuum pump sunction inlet, 6 is the vacuum pump discharge port, 7 is the median septum double-ended face mechanical seal, 8 is the gear, 9 is the bearing, 10 is the drive end cover, 11 is first drive shaft, 12 is the second drive shaft.

In this embodiment, the vacuum driving chamber includes four independently disposed vacuum driving chambers, which are respectively a 1-stage vacuum driving chamber, a 2-stage vacuum driving chamber, a 3-stage vacuum driving chamber and a 4-stage vacuum driving chamber connected in series in sequence, wherein the 1-stage vacuum driving chamber and the 3-stage vacuum driving chamber share one motor drive (as can be seen in the figure, the 1-stage vacuum driving chamber and the 3-stage vacuum driving chamber share a first driving shaft 11 and are connected with the motor through a gear 8), the 2-stage vacuum driving chamber and the 4-stage vacuum driving chamber share a second driving shaft 12, and are driven by another motor, the rotation directions of the rotors of the 1-stage vacuum driving chamber 1 and the 3-stage vacuum driving chamber 3 are the same, but are exactly opposite to the rotation directions of the rotors of the 2-stage vacuum driving chamber and the 4-stage vacuum driving chamber, and the exhaust port of the 1-stage vacuum driving chamber and the suction port of the 2-stage vacuum driving chamber are disposed in the same direction, i, the exhaust port of the 2-stage vacuum driving cavity and the suction inlet of the 3-stage vacuum driving cavity are arranged in the same direction, and the exhaust port of the 3-stage vacuum driving cavity and the suction inlet of the 4-stage vacuum driving cavity are arranged in the same direction.

The driving shafts of the four vacuum driving chambers are not on the same shaft in the embodiment, which is completely different from the existing multi-stage roots vacuum pump, claw vacuum pump and screw vacuum pump.

In another embodiment of fig. 2-1, the stage 1 vacuum drive chamber 1 and the stage 3 vacuum drive chamber 3 are driven by a common drive shaft 13. The common drive shaft 13 is formed by at least two separate drive shafts, in this case three separate drive shafts 131, 132, 133 forming the common drive shaft 13. Wherein the first separation driving shaft 131 is located in the stage 1 vacuum driving chamber 1; the second split drive shaft 132 is located within the 3-stage vacuum drive chamber 3. The first separating driving shaft 131 is located at one side of the second separating driving shaft 132, and the third separating driving shaft 133 is located at the other side of the second separating driving shaft 132. Wherein the first split driving shaft 131 is connected to the second split driving shaft 132 by a first connecting member 136, and the first split driving shaft 131 is spaced apart from the second split driving shaft 132; and the second separating driving shaft 132 is connected with the third separating driving shaft 133 by a second connecting member 137.

In the example of this embodiment, the dual motors are adopted, and the rotation speeds of the two driving shafts are different at different rotation speeds, the rotation speeds of the rotors in the 1-stage vacuum driving cavity, the 3-stage vacuum driving cavity and the 2-stage vacuum driving cavity are different, and the rotation speeds of the rotors in the 4-stage vacuum driving cavity are opposite, so that the shortest distance between the air flows passing through the 4 vacuum driving cavities is realized, and no dead angle exists. This is a substantial difference from the existing multi-stage roots vacuum pumps and claw vacuum pumps. The variable compression ratio in the vacuum driving cavity can be realized due to the adjustable rotating speed, so that the multi-driving-cavity non-coaxial or incomplete-coaxial vacuum pump has the characteristic that the vacuum degree and the suction amount of a pump suction inlet can be adjusted through the rotating speed, which is not possessed by any other vacuum pump. The principle is that the original compression ratio of the vacuum driving cavity is changed through different speeds, so that the vacuum degree and the suction amount of the suction port of the 1-stage vacuum driving cavity are influenced. The actual requirements of the customers can be really realized.

The existing multi-stage roots pump adopts a coaxial design, namely impellers of the multi-stage roots pump are arranged on the same shaft, so that gas exhausted from a certain stage of exhaust port needs to be wound to the other side of the stage of exhaust port to enter the gas inlet of the next stage. Unlike a multi-stage roots pump, the vacuum driving impeller shaft of the multi-driving cavity is non-coaxial, and the impeller steering can be flexibly arranged, so that one advantage of the non-coaxial vacuum cavity driving is that the air flow can be flexibly arranged along the principle of the most straight and shortest path flow, and the exhausted air does not need to be wound back to the other side of the exhaust port of the stage to enter the air inlet of the next stage unlike the multi-stage roots pump, so that the energy is lost in the long-range flow of the air, and the dust in the air is easier to decelerate and settle, and the passage is blocked.

Similarly, the advantage that the gas can flow smoothly along the gravity direction and the air quantity direction and pass through the large-sized exhaust port, so that the dust wrapped in the gas can be discharged easily is remarkably superior to the advantage that the gas in the screw pump moves horizontally in the closed rectangular cavity, and the wrapped dust can not be discharged from the small exhaust port at the single side of the tail end by virtue of gravity and air flow.

And, compare multistage roots pump again, because coaxial design for the progression can not too much, the size can not too big, otherwise the axle can become very long, mechanical stability descends. The invention is not so limited.

Fig. 4 and 5 are another arrangement of the present embodiment. In the figure: the vacuum pump comprises a vacuum driving cavity 1, a vacuum driving cavity 2, a vacuum pump suction inlet 5, a vacuum pump discharge outlet 6, a middle partition plate double-end-face mechanical seal 7, a gear 8, a shared driving shaft 13, a first driven shaft 14 and a second driven shaft 15. The vacuum driving cavity of the present embodiment adopts a staggered arrangement form, the rotation direction of the rotor of the 1-stage vacuum driving cavity 1 is opposite to the rotor direction of the 2-stage vacuum driving cavity 2 (the driving shafts of the 1-stage vacuum driving cavity 1 and the 2-stage vacuum driving cavity 2 are the same common driving shaft 13, but the driven shafts thereof are staggered, so that the rotation directions of the two are opposite), the rotation direction of the rotor of the 3-stage vacuum driving cavity is also opposite to the rotation direction of the rotor of the 4-stage vacuum driving cavity (the driving shafts of the 3-stage vacuum driving cavity and the 4-stage vacuum driving cavity are the same shaft, but the driven shafts thereof are staggered, so that the rotation directions of the two are opposite), similarly, the exhaust port of the 1-stage vacuum driving cavity and the suction port of the 2-, namely, the exhaust port of the 2-stage vacuum driving cavity and the suction port of the 3-stage vacuum driving cavity are arranged in the same direction, and the exhaust port of the 3-stage vacuum driving cavity and the suction port of the 4-stage vacuum driving cavity are arranged in the same direction.

It should be noted that, in the above example, we refer to the 4-stage driving chamber, the 1 and 3 driving chambers are in the same direction of rotation, and the 2 and 4 drivers are in the same direction of rotation in opposite directions, and a two-shaft differential motor is adopted, which is just one specific arrangement of the application principle of the present invention. In fact, the specific arrangement of the present invention may be a number of vacuum drive chamber stages, a number of specific vacuum drive chamber rotation directions, and a number of different types of motors, depending on the vacuum requirements of the customer application and the pump body requirements of each working vacuum section.

In another embodiment of fig. 5-1, in which the common drive shaft 13 is constituted by at least two separate drive shafts, in this embodiment the common drive shaft 13 is constituted by three separate drive shafts 131, 132, 133. Wherein the first separation driving shaft 131 is located in the stage 1 vacuum driving chamber 1; the second split drive shaft 132 is located within the 2-stage vacuum drive chamber 2. The first separating driving shaft 131 is located at one side of the second separating driving shaft 132, and the third separating driving shaft 133 is located at the other side of the second separating driving shaft 132. Wherein the first split driving shaft 131 is connected to the second split driving shaft 132 by a first connecting member 136, and the first split driving shaft 131 is spaced apart from the second split driving shaft 132; and the second separating driving shaft 132 is connected with the third separating driving shaft 133 by a second connecting member 137.

Wherein the rear end 1311 of the first separating driving shaft 131, the rear end 141 of the first driven shaft 14, and the rear end 151 of the second driven shaft 15 have the same pattern in a uniform manner, so as to facilitate modular production.

As shown in fig. 5-1, the 1-stage vacuum driving chamber 1 includes the first driven shaft 14 therein, and the first driven shaft 14 is connected to a first gear 81; wherein the first split drive shaft 131 is connected to a second gear 82; the first gear 81 engages the second gear 82.

Wherein the 2-stage vacuum driving chamber 2 comprises the second driven shaft 15, and the second driven shaft 15 is connected with a third gear 83; wherein the second split drive shaft 132 is connected to a fourth gear 84; the third gear 83 engages the fourth gear 84.

The purpose of the above arrangement is to avoid the mutual interference of each vacuum driving chamber, so that the common driving shaft 13 is "disconnected" into at least two separate driving shafts, which can still transmit torque, and can eliminate the axial influence of the separate driving shaft of one vacuum driving chamber on the separate driving shaft of another connected vacuum driving chamber caused by thermal expansion and cold contraction, thereby ensuring that the impeller and the separate driving shaft in each vacuum driving chamber are not influenced by the expansion or contraction of the impeller and the separate driving shaft caused by thermal expansion and cold contraction of the adjacent vacuum driving chambers. This is advantageous for enlarging the multi-stage roots pump.

The present invention can also be used with the same principle of controlling the speed of each stage with each existing type of roots pump plus variable frequency motor or gearbox, including but not limited to, series-all-pass series or rotary series, longitudinal arrangement, stepped arrangement (using side vent steering) or horizontal arrangement, or parallel, or hybrid series-parallel integrated multi-stage vacuum pumps comprising at least one common drive shaft, where each roots pump is a drive chamber.

The vacuum principle of the variable-speed variable-capacity dry vacuum pump with the multiple driving cavities and non-coaxiality or incomplete coaxiality accords with the fluid mechanics principle with the existing multi-stage Roots vacuum pump, claw vacuum pump and screw vacuum pump, namely, the gas at the vacuum suction inlet is compressed step by utilizing a variable-volume compression mode, and finally the gas is discharged by exceeding the atmospheric pressure. However, in addition to the various features of the present invention described above, there are various points or advantages over other existing dry pumps, respectively: compared with the existing multi-stage roots pump, the existing multi-stage roots pump adopts a coaxial integrated design, so that the compression ratio among stages, the position relation among vacuum cavities and the airflow direction are all completely fixed forever. Thus, the compression ratio between the pump chambers of the respective stages cannot be adjusted in any operating pressure range. Because the compression ratio of the Roots vacuum pump under the rough vacuum condition cannot be too large, otherwise, the pump is blocked due to too large temperature rise of the pump; and can be large under high vacuum, low compression ratios can reduce efficiency. Therefore, a multistage roots pump in which the position and the rotation speed of the vacuum chamber are coaxially fixed cannot maintain optimal performance in each vacuum degree range. The non-coaxial multi-stage Roots pump is driven by different driving motors, so that the rotating speed of each vacuum driving cavity can be flexibly adjusted at any time (or during design) according to different rotating speeds, the interstage compression ratio is further changed, the pump can give consideration to safety and efficiency, optimization and controllability are achieved, namely the differential pressure sharing and the heat sharing of each stage are more uniform, but the coaxial multi-stage Roots pump only shares the uniformity at the beginning stage, and most of the burden is pressed to the last stage when high vacuum is achieved.

Compared to dry plunger pumps and direct atmospheric air-cooled pumps: in the positive displacement dry vacuum pump, the process gas is continuously compressed and exhausted to reach a high vacuum degree, and like a reciprocating pump and a gas-cooled roots vacuum pump which directly exhausts the atmosphere, part of the process gas circulates in a pump cavity or a system and is repeatedly compressed, so that a suction port of the vacuum pump is influenced by the residual gas, and when a piston of the reciprocating pump returns or the gas returns after the gas-cooled pump is cooled, the gas expands to occupy the working space of the positive displacement pump, so that the gas cannot reach the high vacuum degree, extra power is consumed, and extra mechanical materials are wasted. Although the multi-drive cavity non-coaxial or incomplete coaxial variable-speed variable-capacity dry vacuum pump has 4 or more independent and mutually-sealed vacuum drive cavities, all process gases are continuously compressed and then directly discharged, so that the efficiency is highest.

When the multi-stage vacuum pump is coaxial with the driving motor, the connection between the vacuum cavity and the motor shaft can also adopt a sectional connecting key connecting shaft.

It is to be understood that the described embodiments are merely a few embodiments of the invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Claims (9)

1. A multi-stage vacuum pump with a common driving shaft comprises a plurality of independent vacuum driving cavities, wherein the vacuum driving cavities are connected in series or in parallel to form the multi-stage vacuum driving cavities, and each independent vacuum driving cavity is internally provided with at least one rotor;

wherein at least two vacuum drive chambers are driven by a common drive shaft, wherein the common drive shaft comprises at least two separate drive shafts.

2. The multi-stage vacuum pump of claim 1, wherein the at least two vacuum drive chambers driven by the common drive shaft are a first vacuum drive chamber and a second vacuum drive chamber, respectively, the common drive shaft comprising a first split drive shaft and a second split drive shaft, the first split drive shaft being located in the first vacuum drive chamber and the second split drive shaft being located in the second vacuum drive chamber, wherein the first split drive shaft and the second split drive shaft are connected by a first connection member and the first split drive shaft is spaced apart from the second split drive shaft.

3. A common drive shaft multi-stage vacuum pump according to claim 2, wherein the common drive shaft further comprises a third split drive shaft, the first split drive shaft being located on one side of the second split drive shaft and the third split drive shaft being located on the other side of the second split drive shaft, the second split drive shaft and the third split drive shaft being connected by a second connection.

4. A multi-stage vacuum pump with a common drive shaft as in claim 3, wherein the third split drive shaft is connected to a motor shaft of a drive motor.

5. The multi-stage vacuum pump with a common drive shaft of claim 2, further comprising a first driven shaft in the first vacuum drive chamber, the first driven shaft being connected to a first gear; wherein the first split drive shaft is connected with a second gear; the first gear engages the second gear.

6. A multi-stage vacuum pump having a common drive shaft as in claim 2, further comprising a second driven shaft within the second vacuum drive chamber, the second driven shaft being coupled to a third gear; wherein the second split drive shaft is connected with a fourth gear; the third gear engages the fourth gear.

7. A multi-stage vacuum pump with a common drive shaft as in claim 1, wherein the vacuum pump comprising a plurality of vacuum drive chambers is a coaxial multi-stage pump.

8. A multi-stage vacuum pump sharing a drive shaft as claimed in claim 7, wherein the vacuum pump is a multi-stage roots pump or a screw vacuum pump or a multi-stage claw vacuum pump.

9. A multi-stage vacuum pump having a common drive shaft as in claim 1, wherein the vacuum pump is a non-coaxial multi-stage vacuum pump having at least one coaxial shaft.

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