JPH03264795A - Turbo molecular pump - Google Patents

Abstract

PURPOSE:To facilitate position alignment by selectively spigot joint-fitting each boss for preventing floating and for balancing, protruded in the direction of an axial line, to the central part of a rotary unit having moving blades opposed to multistep parallelly arranged stationary blades, so that these bosses can be fixed to a rotary shaft through the rotary unit. CONSTITUTION:A balancing boss 31, having a mounting flange 32, is spigot joint-fitted to a protruded part 18 of a rotary unit 14, having moving blades 16 opposed to multistep parallelly arranged stationary blades 4, and fixed to an upper end part of a rotary shaft 10 through the rotary unit 14 by a screw 17. A stepped floating-preventing boss 35, having a mounting flange 36, is spigot joint-fitted to the protruded part 18 of the rotary unit 14 and fixed to the upper end part of the rotary shaft 10 through the rotary unit 14 similarly by the screw 17. These bosses 31, 36 are selectively mounted to the rotary unit 14. Positioning can be facilitated on an equal axial line to the rotary shaft 10 by spigot joint-fitting the balancing boss 31 thus to the protruded part 18 of the rotary unit 14.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a turbomolecular pump suitable for use in semiconductor manufacturing processes.

[Conventional technology]

For example, semiconductor manufacturing equipment and the like require a chamber with a high vacuum inside.

To form this type of vacuum chamber, a turbo-molecular pump, which has excellent pumping performance in the molecular flow region, is generally employed.

Conventionally, this type of turbomolecular pump has been developed, for example, in Japanese Patent Application Laid-open No.
It is disclosed in Japanese Patent No. 135694 and is authoritative as shown in FIG. To explain this based on the same figure, in the same figure, what is indicated by reference numeral 1 is the suction port 2 and the discharge port 3.
The entire pump casing has a cylindrical shape, with stator vanes 4 and spacers 5 on the inner circumferential wall.
They are provided in multiple stages in the axial direction via. Further, flanges la and lb for fixing a vacuum chamber (not shown) and a support body 6 are provided at each of the upper and lower ends of the pump casing 1.
are integrated. Reference numeral 7 denotes a spherical spiral groove bearing that pivotally supports the lower end of the rotating shaft, which will be described later, and is filled with a spherical part 7a in which a spiral groove is formed, a saucer 7b having a spherical recess for receiving the spherical part 7a, and these members. It consists of lubricating oil 7c as a lubricant, and is provided in the center of the support body 6 via a retainer 8. Reference numeral 9 denotes a frame body having a mounting flange 9a at its lower end, which is provided around the spherical spiral groove bearing 7 and fixed onto the support body 6. Reference numeral 10 denotes a rotating shaft, a part of which faces inside the frame 9, which is rotatably provided inside the pump casing 1, and whose lower end is supported by the spherical spiral groove bearing 7. 11 is a drive mechanism for pump operation;
It consists of a motor rotor 12 fixed to the rotating shaft 9, and a motor stator 13 provided around the motor rotor 12 and fixed to the inner peripheral surface of the frame 9, and is housed in the pump casing l. . Reference numeral 14 denotes a rotating body having a rotor 15 having an H-shaped cross section and moving blades 16 facing the stator blades 4, which is provided on the same axis as the drive mechanism 11 and fixed onto the rotational axis lO by bolts 17. has been done. The rotor 15 of the rotating body 14 is provided with a convex portion 18 that projects upward from the axis. Reference numeral 19 denotes a step-shaped balancing boss, which is connected to the convex portion 18 of the rotating body 14.
The rotary ring 10 is fitted with a spigot, and is fixed to the tip of the rotary ring 10 by the bolt 17. 20 is inlet 2
0a, which is integrally provided in the vacuum chamber (not shown) and the pump casing l;
A convex portion 22 is provided at the center to which a shaft 21 for preventing lifting is attached. Further, 23 is a discharge pipe fixed to the support body 6 and communicating with the discharge port 3, and 24 is fixed to the frame body 9 and has a mechanical protection function to prevent the rotating body 14 from falling due to external disturbances, etc. It is a touchdown bearing. In addition, the reference numeral 25 in the figure indicates the balancing boss 1.
9 is a dummy shaft for balancing fixed by screws 26.

In the turbo molecular pump configured in this way, when the rotating body 14 is rotated by the drive mechanism 11, gas molecules are transferred from the suction port 2 to the discharge port 3 due to the interaction between the stationary blades 4 and the rotor blades 16.
sent to.

Note that during abnormal operation when atmospheric pressure acts on the discharge side of the pump casing 1, the rotating body 14 momentarily moves toward the vacuum chamber (not shown) due to the pressure difference, causing the spherical portion 7a of the spherical spiral groove bearing 7 to Although it separates from the saucer 7b, its movement is restricted by the shaft 21.

By the way, the rotating body 1 in this type of turbomolecular pump
4, the dummy shaft 25 is attached to the upper end of the balancing boss 19 with a screw 26 to adjust its axial center, and then the dummy shaft 25 and the spherical spiral groove bearing 7 are connected to a balancing machine (not shown). ) is assembled into the corresponding parts of the parts.

Thereafter, the dummy shaft 25 is removed from the balancing boss 19.

The axial center adjustment of the dummy shaft 25 is performed while checking the shaft runout using a dial gauge (not shown) or the like.

[Problem to be solved by the invention]

However, the conventional turbo-molecular pump does not have a function of positioning the dummy shaft 25 on the axis of the rotating shaft 10, and therefore, it is necessary to pay close attention to the adjustment of the shaft center. That is, if the dummy shaft 25 is eccentrically attached to the balancing boss 19, the balancing accuracy will be reduced. As a result, the dummy shaft 25
There was a problem that the installation was complicated.

Therefore, it is conceivable to set the axial dimension of the balancing boss 19 to a sufficiently large dimension so that it can serve as both the balancing shaft and the lifting prevention boss, but in this case, the axial dimension of the pump casing 1 will also become large. However, there was an inconvenience that the pump became larger.

The present invention has been made in view of the above circumstances, and provides a turbo molecular pump in which a balancing boss can be easily attached and the pump can be prevented from increasing in size. .

[Means to solve the problem]

In the turbo-molecular pump according to the present invention, a lifting prevention boss and a balancing boss that protrude in the axial direction are selectively fitted with a pilot in the radial center of the rotating body, and the rotating body is rotated at the tip of the rotating shaft. It is fixed through the body.

[For production]

In the present invention, the rotating body can be positioned on the axis of the rotating shaft by fitting the balancing boss into the rotating body.

〔Example〕

EMBODIMENT OF THE INVENTION Hereinafter, the structure etc. of this invention will be explained in detail by the Example shown in the figure.

FIG. 1 is a longitudinal cross-sectional view showing a turbomolecular pump according to the present invention. In the figure, the same members as in FIG. In the same figure,
Reference numeral 31 indicates a balancing boss having a mounting flange 32, which is fitted into the convex portion 18 of the rotating body 14 with a spigot, and is connected to the rotating shaft 1 by the screw 17.
0 via the rotating body 14. The flange 32 of the balancing boss 31 has a through hole 34 through which the head of the bolt 33 for fixing the rotating body 14 faces.
is provided. Reference numeral 35 denotes a step-like lift-prevention boss having a mounting flange 36, which is fitted with a spigot into the convex portion 18 of the rotary body 14, and is attached to the upper end of the rotary shaft 10 by the screw 17. has been fixed.

The flange 36 of the lifting prevention boss 35 is provided with a through hole 37 through which the head of the bolt 33 for fixing the rotating body 14 faces. The lifting prevention boss 36 and the balancing boss 31 are selectively attached to the rotating body 14.

In the turbo-molecular pump configured in this way, the balancing boss 31 can be positioned on the same axis as the rotating shaft 10 by fitting the balancing boss 31 into the convex portion 18 of the rotating body 14. There is no need to pay close attention to the adjustment of the axis as in the past.

Furthermore, in this embodiment, the balancing boss 31 can be removed after balancing and the anti-lifting boss 35 can be attached to the rotating body 14, so that the axial dimension of the pump casing 1 can be increased as in the conventional case. There's no need.

In addition, in the present invention, the axial dimension between the lifting prevention boss 35 and the lifting prevention shaft 22 is greater than the axial dimension between the upper and lower ends of any stationary blade 4 and the rotor blade 16 facing these upper and lower ends. Assume that the dimensions are set to small.

〔Effect of the invention〕

As explained above, according to the present invention, the boss for preventing lifting and the boss for balancing that protrude in the axial direction are selectively fitted in the radial center of the rotating body with a pilot fitting, and the tip of the rotating shaft Since it was fixed via a rotating body,
The rotating body can be positioned on the axis of the rotating shaft by fitting a balancing boss into the rotating body. Therefore, it is not necessary to pay close attention to the adjustment of the axis as in the conventional case, so that the balancing boss can be easily attached. In addition, since the balancing boss can be removed after balancing and the anti-lifting boss can be attached to the rotating body, there is no need to increase the axial dimension of the casing as in the past.
It is possible to prevent the pump from increasing in size.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing a turbo-molecular pump according to the present invention, and FIG. 2 is a longitudinal sectional view showing a conventional turbo-molecular pump. 1---Pump casing, 4... stator blade, 10...
...Rotating shaft, 11...Drive mechanism, 12...Motor rotor, 13...Motor stator, 14...
・Rotating body, 16... Moving blade, 18... Convex part, 20
...Bolt, 31 ...Balancing boss, 3
4...Boss to prevent lifting. Agent Masuo Oiwa

Claims (1)

[Claims] A casing having stator blades arranged in parallel in multiple stages in the axial direction, a rotating shaft provided within the casing and rotated by a drive mechanism, and a moving blade fixed to the tip of the rotating shaft and facing the stator blades. In a turbo-molecular pump equipped with a rotating body, a boss for preventing lifting and a boss for balancing that protrude in the axial direction are selectively fitted with a pilot in a radially central portion of the rotating body, and the rotating shaft A turbo molecular pump, characterized in that the pump is fixed to the tip of the pump via the rotating body.