JP6100038B2 - Vacuum pump - Google Patents

Description

  The present invention relates to a vacuum pump having a free mounting posture for compressing gas from medium vacuum to atmospheric pressure, and more particularly to a vacuum pump having a light weight and a simple structure.

  A vacuum pump having an exhaust capability capable of compressing a gas from a medium vacuum to an atmospheric pressure is used for applications such as a sputtering apparatus, a helium leak detector, and an analysis apparatus such as an SEM. Moreover, as a vacuum pump for roughing a high vacuum pump such as a turbo molecular pump, and also as a vacuum pump for sucking a gas such as water vapor such as a vacuum drying / vacuum laminating apparatus, a vacuum pump having the above-mentioned exhaust capability Is used.

  Oil rotary pumps are the mainstream as small-capacity, light-weight vacuum pumps. However, the reverse diffusion of oil vapor into the vacuum chamber (contamination of oil in the vacuum chamber and workpiece), oil contamination in the exhaust line (fire hazard), environmental contamination, oil reduction due to oil splashing, oil deterioration due to moisture mixing, There are various problems such as oil replenishment and oil change required regularly. In particular, fluorinated oil for vacuum pumps is expensive and troublesome to replace.

  Therefore, in recent years, scroll-type dry vacuum pumps have appeared as vacuum pumps that replace oil rotary pumps. The scroll-type dry vacuum pump is oil-free and compresses continuously from the vacuum to the atmospheric pressure by the rocking motion of the scroll. Therefore, it has features such as low power during vacuum operation and relatively good vacuum performance. . However, since a tip seal (contact seal) is used at the end of the scroll, there is a problem that the tip seal is worn and particles are generated, and the inside of the vacuum chamber is contaminated. In addition, since the tip seal is worn, the vacuum performance deteriorates over time, and the tip seal must be replaced in a continuous operation for about one year. Furthermore, when exchanging the tip seal, the vacuum pump must be disassembled, resulting in high replacement costs. In addition, there are problems such as large size and high cost compared to an oil rotary pump of the same capacity.

  As a vacuum pump that can cope with the above problem, there is a vacuum pump described in Patent Document 1 and the like. The vacuum pump of Patent Document 1 employs a magnet coupling type DC brushless motor that rotates in the opposite direction in synchronization with each other without using a timing gear. For this reason, there is no timing gear for synchronizing the two-axis rotor, and the pump configuration is simple with only a drive / synchronization motor and an exhaust screw screw portion.

JP 2010-127119 A

In the vacuum pump disclosed in Patent Document 1, a pump intake port and an exhaust port are provided at one location on the side surface of the casing. The intake port and the exhaust port of the vacuum pump are connected to other devices (vacuum chamber, other true air pump, exhaust gas treatment device, etc.) via respective pipes. At this time, as disclosed in Patent Document 1, in the configuration in which the pump intake port and the exhaust port are provided at one side on the side surface of the casing, the degree of freedom of access is low for the user, and the connection piping There are problems such as complicated handling and limited layout of the exhaust system.
In vacuum chambers for manufacturing semiconductor devices and liquid crystal panels, various treatments are performed using reactive gases and condensable gases. In vacuum pumps that exhaust these reactive gases and condensable gases, vacuum is used. In order to prevent reactive gas or condensable gas from adhering to the inside of the pump, it is necessary to perform purging with an inert gas for the purpose of lowering the partial pressure. Therefore, it is necessary to separately provide a supply port for purging inert gas in the casing of the vacuum pump.

  The present invention has been made in view of the above circumstances, and the degree of freedom of access to the pump intake port and / or the exhaust port is improved, and there is no need to separately provide an inert gas supply port for purging in the casing. An object is to provide a vacuum pump.

According to a first aspect of the present invention, there is provided a pair of rotors arranged opposite to each other, a casing having a first bearing having an intake / exhaust port and defining an inter-axis distance between the pair of rotors, and rotating the rotor A vacuum pump having a motor unit for driving, wherein a plurality of exhaust ports that can be connected to an external device on the exhaust side are formed on the side of the casing where the first bearing is disposed, and one of them is formed. The gas supply port for purging gas is connected to an external device and used as an exhaust port, and it is possible to select which exhaust port is used as an exhaust port from among multiple exhaust ports. It is characterized by that.
According to the present invention, of the two ports on the arrangement side of the first bearing of the casing, one port can be a gas purge port and the other port can be a normal exhaust port. By supplying an inert gas from one port to the exhaust part (atmospheric pressure side), it is possible to promote dilution and discharge of corrosive and condensable gases. With this configuration, it is not necessary to separately provide an inert gas purge port (supply port).
According to a preferred aspect of the present invention, the external device on the exhaust side is another vacuum pump or an exhaust gas treatment device.

According to a second aspect of the present invention, there is provided a pair of rotors arranged opposite to each other, a casing having a first bearing that has an intake / exhaust port and defines an interaxial distance between the pair of rotors, and the rotor is rotated. A vacuum pump having a motor unit for driving, wherein a plurality of intake ports that can be connected to an external device on the intake side are formed on the side of the casing where the first bearing is disposed, and one of them is formed Connected a check valve, connected the rest to an external device, used as an intake port, and made it possible to select which intake port to use as an intake port from among multiple intake ports Features.
According to the present invention, when a large-capacity chamber (atmospheric pressure) is exhausted, a check valve is provided between the booster pump and the subsequent vacuum pump. Since it can be provided at the port for the mouth, it is not necessary to form a port for the check valve in the vacuum pipe connecting the two pumps, and the configuration of the vacuum pipe is simple and small. Depending on the design, the vacuum piping can be eliminated.
According to a preferred aspect of the present invention, the external device on the intake side is a vacuum chamber or other vacuum pump.

According to a preferred aspect of the present invention, the motor section is a magnet coupling type DC brushless motor that rotates the pair of rotors in a reverse direction in synchronization with each other without using a timing gear.
According to the present invention, the timing gear for synchronizing and rotating the pair of pump rotors in the opposite direction and the lubricating oil and the lubrication system for lubricating the timing gear can be omitted. It becomes possible to do. In addition, it is possible to limit the loss of power consumption of the motor unit by limiting the driving force loss that occurs during rotary operation as a vacuum pump to the rotational friction loss of the bearing that supports the rotary shaft of the pump rotor. It becomes.
According to an embodiment of the present invention, a pair of opposed rotors, a casing having intake and exhaust ports and a first bearing that defines an inter-axis distance between the pair of rotors, and rotating the rotor In the vacuum pump including a motor unit to be driven, a plurality of intake ports or exhaust ports formed on the arrangement side of the first bearing of the casing are provided.
According to the above embodiment, since there are a plurality of intake ports or exhaust ports of the vacuum pump, the degree of freedom of access to the pump intake port or exhaust port is improved for the user. When there are a plurality of exhaust ports, one can be used as a normal exhaust port and the other can be used for gas purging. The purpose of the gas purge is to dilute the gas on the atmospheric pressure side (compression side) (decrease in the partial pressure of the condensable gas), to suppress the entry of the reactive gas into the bearing and a gas containing a large amount of moisture.
According to an embodiment of the present invention, the intake ports or exhaust ports provided at the plurality of locations are on the side surface and the end surface of the casing on the arrangement side of the first bearing.
According to the above embodiment, when adopting a magnet coupling type DC brushless motor that rotates in the opposite direction in synchronization with each other without using a timing gear, there is no timing gear for synchronizing the two-axis rotor, and the pump configuration is It has a simple configuration with only a drive / synchronization motor and an exhaust screw thread. If there is a conventional timing gear, an intake port or an exhaust port cannot be provided on the end face side, but the vacuum pump of the present invention is a portion opposite to the side where the motor is arranged, that is, the first part of the casing. The side surface and the end surface on the arrangement side of one bearing have a simple configuration, and a plurality of intake ports or exhaust ports can be provided.

The present invention has the following effects.
(1) Since there are a plurality of intake ports or exhaust ports of the vacuum pump, the degree of freedom of access to the pump intake port or exhaust port is improved for the user. When there are a plurality of exhaust ports, one can be used as a normal exhaust port and the other can be used for gas purging. The purpose of the gas purge is to dilute the gas on the atmospheric pressure side (compression side) (decrease in the partial pressure of the condensable gas), to suppress the entry of the reactive gas into the bearing and a gas containing a large amount of moisture.
(2) When the port on the side opposite to the side where the motor is arranged is an intake port and there are a plurality of ports, if all the ports are used as the intake ports, the gas flow passage area will be multiple. Therefore, the conductance is increased, and the performance loss due to the pipe conductance at the pump inlet is reduced.
(3) When exhausting a large-capacity chamber (atmospheric pressure), a check valve is provided between the booster pump and the downstream vacuum pump. This check valve is connected to the intake port of the downstream vacuum pump. Therefore, it is not necessary to form a check valve port in the vacuum pipe connecting the two pumps, and the configuration of the vacuum pipe becomes simple and small. Depending on the design, the vacuum piping can be eliminated.

1A and 1B are schematic cross-sectional views showing a basic configuration of a vacuum pump according to the present invention. FIG. 2 is a longitudinal sectional view showing a first embodiment of the vacuum pump according to the present invention. FIG. 3 is a longitudinal sectional view showing a second embodiment of the vacuum pump according to the present invention. FIG. 4 is a cross-sectional view of an essential part showing an embodiment in which one of the two ports on the arrangement side of the first bearing of the pump casing is a normal exhaust port and the other port is a gas purge port. It is. 5 (a) and 5 (b) show an exhaust system using a conventional vacuum pump having only one intake port (FIG. 5 (a)) and an exhaust system using the vacuum pump of the present invention having a plurality of intake ports. It is typical sectional drawing which compares and shows a system (FIG.5 (b)). 6 (a), (b), (c), and (d) are diagrams showing the vacuum pump of the present invention, FIG. 6 (a) is a schematic longitudinal sectional view of the vacuum pump, and FIG. 6 (b). Fig. 6A is a schematic side view of Fig. 6A, Fig. 6C is a schematic cross-sectional view of the vacuum pump, and Fig. 6D is a schematic side view of Fig. 6C. 7 (a), (b), (c), and (d) are diagrams showing the vacuum pump of the present invention, FIG. 7 (a) is a schematic longitudinal sectional view of the vacuum pump, and FIG. 7 (b). 7A is a schematic side view of FIG. 7A, FIG. 7C is a schematic cross-sectional view of the vacuum pump, and FIG. 7D is a schematic side view of FIG. 7C. FIGS. 8A and 8B are schematic views showing an example in which two vacuum pumps are connected in series. FIGS. 9A and 9B are schematic views showing another example in the case where two vacuum pumps are connected in series.

Embodiments of a vacuum pump according to the present invention will be described below with reference to FIGS. 1 to 9, the same or corresponding components are denoted by the same reference numerals, and redundant description is omitted.
1A and 1B are schematic cross-sectional views showing a basic configuration of a vacuum pump according to the present invention. As shown in FIGS. 1A and 1B, a pump casing 1, a pair of rotors 2 (only one rotor is shown in the illustrated example) disposed opposite to each other in the pump casing 1, and a pair of rotors 2. The motor part 10 which rotationally drives is provided. The pair of rotors are supported by a pair of first bearings 3 (only one bearing is shown in the illustrated example) fixed to the pump casing 1 and a bearing plate 4 provided at the opening end of the pump casing 1. The second bearing 5 is rotatably supported. The distance between the shafts of the pair of rotors 2 is set to a predetermined dimension by defining the position of the first bearing 3 and the position of the second bearing 5.

In the example shown in FIG. 1A, a side air inlet SP <b> 1 is provided on the side surface of the pump casing 1, and an end surface side air inlet SP <b> 2 is provided on the end surface of the pump casing 1. That is, the vacuum pump is provided with two intake ports SP1 and SP2. Further, one exhaust port DP is provided on the side surface of the pump casing 1.
In the example shown in FIG. 1B, one intake port SP is provided on the side surface of the pump casing 1. Further, the side surface of the pump casing 1 is provided with a side surface side exhaust port DP1, and the end surface of the pump casing 1 is provided with an end surface side exhaust port DP2. That is, the vacuum pump is provided with two exhaust ports DP1 and DP2.
As shown in FIGS. 1 (a) and 1 (b), the vacuum pump of the present invention is provided with a plurality of intake ports SP or exhaust ports DP formed on the arrangement side of the first bearing 3 of the pump casing 1. Yes.

Next, an embodiment of a vacuum pump that embodies the vacuum pump of the present invention shown in FIGS. 1 (a) and 1 (b) will be described.
FIG. 2 is a longitudinal sectional view showing a first embodiment of the vacuum pump according to the present invention. As shown in FIG. 2, the vacuum pump includes a pump casing 1, a pair of rotors 2, 2 disposed opposite to each other in the pump casing 1, and a motor unit 10 that rotationally drives the pair of rotors 2, 2. I have. The pair of rotors 2 and 2 includes a pair of first bearings 3 and 3 fixed to the pump casing 1 and a pair of second bearings supported by a bearing plate 4 provided at an opening end of the pump casing 1. 5 and 5 are rotatably supported. An inter-axis distance L between the pair of rotors 2 and 2 is set to a predetermined dimension by defining the positions of the first bearings 3 and 3 and the positions of the second bearings 5 and 5. The positions of the first bearings 3, 3 are defined by bearing support portions 1 a, 1 a made of circular holes formed in the pump casing 1, and the positions of the second bearings 5, 5 are formed on the bearing plate 4. It is prescribed | regulated by the bearing support parts 4a and 4a which consist of circular holes. The second bearings 5 and 5 are pressed by a bearing press 6 fixed to the bearing plate 4.

  As shown in FIG. 2, the pair of rotors 2 and 2 includes a screw rotor in which shaft portions 2A and 2A and screw screw portions 2S and 2S are integrated. That is, each rotor 2 is integrally formed by fitting the shaft portion 2A and the screw screw portion 2S. In the following description, the rotor 2 is also referred to as a screw rotor 2 as appropriate. A fluid flow path 1 fp is formed between the screw rotors 2 and 2 and the inner surface of the pump casing 1. On the arrangement side of the first bearings 3 and 3 of the pump casing 1, a first port P1 constituting a first intake port or an exhaust port and a second port P2 constituting a second intake port or an exhaust port. And are provided. The first port P <b> 1 is provided on the side surface of the pump casing 1, and the second port P <b> 2 is provided on the end surface of the pump casing 1. The second port P2 is installed on the outer peripheral side of the first bearing. In addition, a port P constituting an intake port or an exhaust port is provided on the side of the pump casing 1 where the motor unit 10 is disposed. That is, when the port P is an intake port, the first port P1 and the second port P2 become a first exhaust port and a second exhaust port, respectively. When the port P is an exhaust port, the first port P1 and the second port P2 become a first intake port and a second intake port, respectively. The screw rotors 2 and 2 are reversed in a non-contact manner while maintaining a slight clearance, and transfer the gas sucked from the intake port to the exhaust port.

  The motor unit 10 is composed of a magnet coupling type DC brushless motor. A pair of magnet rotors 11 and 11 having the same configuration are disposed at the shaft ends of the shaft portions 2A and 2A of the pair of rotors 2 and 2, respectively, and reversely drive the screw rotors 2 and 2 as DC brushless motors. At the same time, the screw rotors 2 and 2 are rotated in the reverse direction in synchronization with each other by magnet coupling. Each magnet rotor 11 is provided with a ring-shaped magnet around the outer periphery of a magnetic yoke. In the present embodiment, magnetized magnets are provided on the outer periphery of the magnet rotor 11 so as to face each other so that the different magnetic poles of the magnet rotors 11 and 11 are attracted to each other and maintain a clearance. The number of poles of the magnet rotor 11 is an even number such as 4, 6, 8,.

  A three-phase (U, V, W) motor stator 12 including an iron core 12a and a winding 12b is disposed in the vicinity of a part of the outer peripheral surface of each magnet rotor 11. The pair of three-phase motor stators 12, 12 are disposed on the opposite side of the rotating shaft from the side on which the pair of magnet rotors 11, 11 are magnet-coupled. Thereby, the magnet coupling force that the magnet rotors 11 and 11 attract each other can be canceled by the attraction force acting on the magnet rotor 11 and the motor stator core 12a. The three-phase motor stator magnetic poles correspond to the number of magnetic poles of the magnet rotor 11 and apply a magnetic field to each pole of the magnet rotor 11. By supplying a required direct current to the three-phase winding 12b, the pair of rotors 2 and 2 can be synchronously inverted and driven at an arbitrary rotational speed.

  FIG. 3 is a longitudinal sectional view showing a second embodiment of the vacuum pump according to the present invention. In the present embodiment, the second port P2 constituting the second intake port or the exhaust port on the arrangement side of the first bearings 3 and 3 of the pump casing 1 is connected to the pair of first bearings 3 and 3. It is formed between. The other structure is the same as that of the vacuum pump shown in FIG.

  The vacuum pump of the present invention employs a magnet coupling type DC brushless motor that rotates in the opposite direction in synchronization with each other without using a timing gear. Therefore, there is no timing gear for synchronizing the two-axis rotor, and the pump configuration is a simple configuration including only a driving / synchronizing motor and an exhaust screw screw portion. In particular, on the side opposite to the side where the motor is arranged, only the end portion of the screw screw and the bearing supporting the shaft are arranged. An intake port or an exhaust port of the pump can be arranged at the end of the screw screw, and it is optional. This is because it can be selected depending on the rotation direction of the rotor. The portion opposite to the side where the motor is disposed has a simple configuration as described above, and can have a plurality of intake ports or exhaust ports. For example, if there is a conventional timing gear, it is not possible to provide an intake port or an exhaust port on the end face side. This is because oil is supplied to the timing gear portion to prevent sag. The advantage of having a plurality of intake ports or exhaust ports of the vacuum pump is that the user has a higher degree of freedom in accessing the pump intake port or exhaust port. As another effect, when there are a plurality of exhaust ports, one can be used as a normal exhaust port and the other can be used for gas purging. The purpose of the gas purge is to dilute the gas on the atmospheric pressure side (compression side) (decrease in the partial pressure of the condensable gas), to suppress the entry of the reactive gas into the bearing and a gas containing a large amount of moisture.

FIG. 4 shows an embodiment in which one of the two ports on the arrangement side of the first bearings 3 and 3 of the pump casing 1 is a normal exhaust port and the other port is a gas purge port. It is principal part sectional drawing. As shown in FIG. 4, of the two ports on the arrangement side of the first bearings 3 and 3 of the pump casing 1, the first port P1 is a normal exhaust port, and the second port P2 is for gas purge. Port. By supplying an inert gas from the second port P2 to the exhaust part (atmospheric pressure side), it is possible to promote dilution and discharge of corrosive and condensable gas. With the configuration shown in FIG. 4, it is not necessary to separately provide an inert gas purge port (supply port). Note that the inert gas for purging, may be used N _2, may be any gas which does not react with condensable gases like other than N _2, for example, the He, Ar, rare gas Kr like and CO ₂ is acceptable.

  In the case where there are a plurality of ports on the side opposite to the side where the motor is disposed and there are a plurality of ports, that is, in the example shown in FIGS. 2 and 3, the first port P1 and the second port P2 are the intake ports. When doing so, there are the following merits. In the case of the intake port, the atmosphere is vacuum and conductance is smaller than that on the atmospheric pressure side. If all of the plurality of ports are used as the intake port, the gas flow passage area is increased by the number of ports, the conductance is increased, and the performance loss due to the pipe conductance at the pump intake port portion is reduced.

When a plurality of ports are used as intake ports, for example, when the first port P1 and the second port P2 are used as intake ports in the example shown in FIGS. 2 and 3, a check valve is provided for one port. be able to.
5 (a) and 5 (b) show an exhaust system using a conventional vacuum pump having only one intake port (FIG. 5 (a)) and an exhaust system using the vacuum pump of the present invention having a plurality of intake ports. It is typical sectional drawing which compares and shows a system (FIG.5 (b)).
In FIG. 5A, a conventional vacuum pump VAC is a vacuum pump using a motor that requires a timing gear that synchronizes a two-axis rotor. In FIG.5 (b), the vacuum pump VAC of this invention has simplified and shown the vacuum pump shown in FIG.

  As shown in FIGS. 5A and 5B, when the booster pump BP is provided upstream and the large-capacity chamber (atmospheric pressure) is exhausted, the first booster pump BP is more Since the exhaust speed is higher than that of the vacuum pump VAC, a large amount of gas is compressed and exhausted to the subsequent vacuum pump VAC. The pressure at the intake port of the vacuum pump VAC at the rear stage increases momentarily, and the booster pump BP at the first stage is operated in a high pressure state and requires very large driving power. As a method for avoiding the above-described state, a check valve V1 is provided between the connections of the two pumps, and a method of forcibly removing gas when an overcompressed state (atmospheric pressure or higher) is reached is employed. Therefore, in the conventional exhaust system shown in FIG. 5 (a), a connection port 20P for providing the check valve V1 is required in the portion of the vacuum pipe 20 that connects the booster pump BP and the vacuum pump VAC. .

  On the other hand, the vacuum pump VAC of the present invention shown in FIG. 5B employs a magnet coupling type DC brushless motor that rotates a pair of rotors in the opposite direction in synchronization with each other without using a timing gear. Therefore, compared with the configuration with the timing gear, the configuration on one side of the pump (the side opposite to the side where the motor is arranged) is very simple. By providing the port P2 on the pump end face of this simple configuration and providing the check valve V1 for the above purpose at this port P2, the configuration of the vacuum pipe 20 connecting the two pumps is also very simple and compact. It becomes possible. Depending on the design, it is possible to eliminate the vacuum piping and connect the exhaust ports and intake ports of the two pumps directly.

Next, further features of the vacuum pump of the present invention will be described.
6 (a), (b), (c), and (d) are diagrams showing the vacuum pump of the present invention, FIG. 6 (a) is a schematic longitudinal sectional view of the vacuum pump, and FIG. 6 (b). Fig. 6A is a schematic side view of Fig. 6A, Fig. 6C is a schematic horizontal sectional view of the vacuum pump, and Fig. 6D is a schematic side view of Fig. 6C.
6 (a) to 6 (d), a surface indicated by a thick solid line is used as a reference plane A, and the positions shown in FIGS. 6 (a) to 6 (d) are set to the first state (basic form) with respect to the positions of the intake port and the exhaust port. ).

7 (a), (b), (c), and (d) are diagrams showing the vacuum pump of the present invention, FIG. 7 (a) is a schematic longitudinal sectional view of the vacuum pump, and FIG. 7 (b). Fig. 7A is a schematic side view of Fig. 7A, Fig. 7C is a schematic horizontal sectional view of the vacuum pump, and Fig. 7D is a schematic side view of Fig. 7C.
7A to 7D, the surface indicated by the thick solid line is the reference surface A (same as the reference surface A in FIG. 6), and the left and right screw rotors (a pair of rotors) 2 are left as they are. When the motor unit 10 and the casing 1 are assembled by reversing 180 degrees, the rotation directions of the left and right rotors are reversed, so that the gas exhaust direction (compression direction) is reversed. Thereby, the position of the inlet port and the outlet port of the pump can be reversed from the positions of FIGS. This method is very simple because the positions of the intake port and the exhaust port can be changed without changing the parts.

By using the above features, for example, when two pumps are connected in series, they can be connected efficiently, and by adding the feature of providing a plurality of intake / exhaust ports, it is compact and accessible. A good exhaust unit can be constructed. Examples of these configurations are shown below.
FIGS. 8A and 8B are schematic views showing an example in which two vacuum pumps are connected in series. When the positional relationship (gas compression direction) of the two vacuum pumps connected in series is the same and the gas pump is connected without any ingenuity, the result is as shown in FIG. That is, the exhaust port of the vacuum pump VAC1 and the intake port of the vacuum pump VAC2 are opposite to each other in the axial direction, and a long vacuum pipe 20 connecting the intake ports and the exhaust ports of the two pumps VAC1, VAC2 is required. If the two pumps connected in series are called pump units, the entire intake / exhaust ports of the pump unit are arranged in two directions on the upper and lower surfaces.

  Next, as shown in FIG. 8B, the casing and the motor unit in the pump VAC1 located above the two pumps VAC1 and VAC2 are inverted 180 degrees and assembled. The left and right screw rotors are left as they are. Then, the compression direction of the gas is opposite to that in FIG. 8A, and the positions of the intake port and the exhaust port are also changed. If it carries out like this, connection of two pumps VAC1 and VAC2 will become very simple, and the vacuum piping 20 for connection can be shortened. However, the position of the entire inlet / outlet of the pump unit is in two directions, the upper and lower surfaces.

FIGS. 9A and 9B are schematic views showing another example in the case where two vacuum pumps are connected in series. In the example shown in FIG. 9A, the intake / exhaust ports of the two pumps VAC1, VAC2 are formed on the side surface side. If the intake and exhaust ports on the side surfaces are formed on both sides and one is not closed, the upper and lower casings cannot be shared. The merit in this case is that the suction port and the exhaust port of the pump unit are aligned to the side surface, the connection vacuum pipe 20 is shortened, and one-way access is possible.
In the example shown in FIG. 9B, intake and exhaust ports are provided on the end face sides of the casings of the two pumps VAC1 and VAC2. In this case, even if the intake / exhaust ports are not formed more than necessary, the casings of the two pumps are made common, and the intake / exhaust ports of the pump unit can be accessed from one direction. It is possible. The casing and motor part of these two pumps can share parts. As a matter of course, the screw rotor can be made common, but there is no particular problem in making it a different specification in order to change the performance of the screw rotor, for example. If the axial length and outer diameter of the rotor are the same, the casing need not be changed.

  Although the embodiment of the present invention has been described so far, the present invention is not limited to the above-described embodiment, and it is needless to say that the present invention may be implemented in various different forms within the scope of the technical idea.

DESCRIPTION OF SYMBOLS 1 Pump casing 1a Bearing support part 1fp Fluid flow path 2 Rotor, screw rotor 2A Shaft part 2S Screw screw part 3 First bearing 4 Bearing plate 4a Bearing support part 5 Second bearing 6 Bearing press 10 Motor part 11 Magnet rotor 12 Motor stator 12a Iron core 12b Winding 20 Vacuum piping BP Booster pump SP Inlet port DP Exhaust port SP1, SP2 Inlet port DP1, DP2 Side exhaust port P port P1 First port P2 Second port VAC, VAC1, VAC2 Vacuum pump V1 Check valve

Claims (5)

A vacuum pump including a pair of rotors arranged opposite to each other, a casing having a first bearing that has an intake / exhaust port and defines an inter-axis distance between the pair of rotors, and a motor unit that rotationally drives the rotor Because
A plurality of exhaust ports that can be connected to an external device on the exhaust side are formed on the arrangement side of the first bearing of the casing, one of which is a gas supply port for purging the gas, and the other is an external port A vacuum pump characterized in that it can be connected to equipment and used as an exhaust port, and an exhaust port to be used as an exhaust port among a plurality of exhaust ports can be selected .   The vacuum pump according to claim 1, wherein the external device on the exhaust side is another vacuum pump or an exhaust gas treatment device. A vacuum pump including a pair of rotors arranged opposite to each other, a casing having a first bearing that has an intake / exhaust port and defines an inter-axis distance between the pair of rotors, and a motor unit that rotationally drives the rotor Because
A plurality of intake ports that can be connected to an external device on the intake side are formed on the arrangement side of the first bearing of the casing, one of which is connected to a check valve, and the rest is connected to the external device. A vacuum pump characterized in that it can be connected and used as an intake port, and of which a plurality of intake port ports can be used as an intake port .   4. The vacuum pump according to claim 3, wherein the external device on the intake side is a vacuum chamber or another vacuum pump.   5. The motor coupling unit according to claim 1, wherein the motor unit is a magnet coupling type DC brushless motor that rotates the pair of rotors in a reverse direction in synchronization with each other without using a timing gear. 6. Vacuum pump.

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