JPH03246396A - Turbo-molecular pump - Google Patents

Abstract

PURPOSE:To reduce cost and to improve exhaust performance as a pump by forming a stator blade in the neighborhood of the discharge side with a relief preventing member for regulating movement in the axial direction of a rotor and by having this member faced between rotor blades. CONSTITUTION:A stator blade in the neighborhood of the discharge side of stator blades 34 paralleled in a number of stages in the axial direction is formed by a relief preventing member 46 for regulating movement in the axial direction of a rotor 44. This relief preventing member 46 is made faced between two rotor blades 45 adjoining each other. At abnormality in operation, a movement stroke of the rotor 44 in the axial direction can be set at a predetermined movement stroke by the relief preventing member 46 on the discharge side of a casing 31. Thus, an expensive ring is made unnecessary and cost can be reduced. Also, as an opening can be formed large enough on the casing suction side, exhaust performance as a pump can be improved.

Description

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

[Conventional technology]

Generally, semiconductor manufacturing equipment and the like require a chamber with a high degree of vacuum, and therefore it is known to use a turbo-molecular pump, which has excellent pumping performance in the molecular region.

Conventionally, this type of turbomolecular pump has been constructed as shown in FIG. To explain this based on the same figure, in the same figure, what is indicated by the symbol l is a pump casing which has an inlet port 2 and a discharge port 3 at each upper and lower end, and is formed into a cylindrical shape as a whole, and has an inner circumferential wall. Stator blades 4 are provided in multiple stages in the axial direction with spacers 5 interposed therebetween. Further, at each upper and lower end of the pump casing 1, there are flanges la for fixing a vacuum chamber (not shown) and a support body 6.
, lb are integrally provided. A stator frame 7 has a mounting flange 7a at its lower end, a part of which faces inside the pump casing 1, and is fixed to the center of the support 6.

8 is a spiral group bearing for high-speed operation, and the spherical spiral group shaft 8 supports the lower end of the rotating shaft, which will be described later.
a, and a bearing body 8b that receives this spherical spiral group shaft 8a, and is attached to the center of the stator frame 7 via a bracket 9. Reference numeral 10 denotes a rotating shaft that partially faces inside the stator frame 7, and is rotatably provided inside the pump casing 1. 1
Reference numeral 1 denotes a drive mechanism for pump operation, which is composed of a motor rotor 12 fixed on the rotating shaft 10 and a motor stator 13 provided around the motor rotor 12 and fixed to the inner peripheral surface of the stator frame 7. , is housed in the pump casing 1. Reference numeral 14 denotes a rotating body having rotor blades 15 opposed to a part of the stationary blades 4, which is provided on the same axis as the drive mechanism 11, and is fixed onto the rotating shaft 10 by a nut 16. Reference numeral 17 denotes a ring having an inlet 17a, which is interposed between the flange 1a of the pump casing 1 and the vacuum chamber (not shown), and has a lifting prevention member 18 and a misalignment prevention member 19 in the center. A post 20 is provided for attaching. Further, 21 is fixed to the support body 6 and the discharge port 3
A discharge pipe 22 communicating with the spherical spiral group bearing 8 is a lubricating oil for lubricating the spherical spiral group bearing 8.

By the way, in the turbo-molecular pump configured in this way, since the operating region is the molecular flow region, a roughing pump is required during normal operation. Therefore, during abnormal operation when atmospheric pressure acts on the discharge side of the pump casing 1, there is a risk that the rotating body 14 will move to the vacuum side (vacuum chamber side) and the spherical spiral group shaft 8a will separate from the bearing body 8b. , a lifting prevention member 18 is usually fixed inside the pump casing 1. Note that the axial dimension between the lifting prevention member 18 and the rotating body 14 is as follows:
The upper and lower ends of any stator blade 4 and the rotor blade 1 that opposes these upper and lower ends
It is assumed that the dimension is set to be smaller than the axial dimension between 5 and 5.

[Problem to be solved by the invention]

However, in the conventional turbo molecular pump, since the ring 17 to which the lifting prevention member 18 is fixed is provided on the suction side of the pump casing 1, the ring 17
Therefore, we needed something with a sealing function. As a result, the material of the ring 17 is a material for high vacuum use, resulting in an increase in cost. In addition, the need for the ring 17 having the boss 20 as the attachment part for the lifting prevention member 18 means that the opening part needs to be set to a smaller size compared to the overall size of the ring, which reduces the pump's exhaust performance. There was also the problem of a decline.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a turbo-molecular pump that can reduce costs and improve the pumping performance of the pump.

[Means to solve the problem]

In the turbo-molecular pump according to the present invention, among the stator vanes arranged in parallel in multiple stages in the axial direction, the stator vanes near the discharge side are formed by a lifting prevention member that restricts the movement of the rotating body in the axial direction,
This lifting prevention member is placed between two adjacent rotor blades.

[For production]

In the present invention, the movement stroke in the axial direction of the rotating body can be set to a predetermined movement stroke by the lifting prevention member on the casing discharge side during abnormal operation.

〔Example〕

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

1 and 2 are cross-sectional views showing the entire turbomolecular pump and essential parts according to the present invention. In the figure, code 3
1 is a pump casing that has a suction port 32 and a discharge port 33 at each of the upper and lower ends, and is formed in a cylindrical shape as a whole, and stator vanes 34 are arranged in multiple stages in the axial direction on the inner circumferential wall through spacers 35. It is set in. Further, a flange 31a to which a vacuum chamber (not shown) and a support body 36 are attached is provided at each upper and lower end of the pump casing 31.
, 32b are integrally provided. 37 is flange 37
A stator frame having a lower end thereof, a part of which faces inside the pump casing 31, and is fixed to the center of the support 36.

Reference numeral 38 designates a spiral group bearing for high-speed operation, which is composed of a spherical spiral group shaft 38a that pivotally supports the lower end of a rotating shaft, which will be described later, and a bearing body 38b that receives this spherical spiral group shaft 38a. It is attached to the section via a bracket 39. 40 is a rotating shaft whose part faces inside the stator frame 37;
It is rotatably provided in the pump casing 31, and its lower end is supported by the spherical spiral groove bearing 38. Reference numeral 41 denotes a drive mechanism for pump operation, which is composed of a motor rotor 42 fixed on the rotating shaft 40 and a motor stator 43 provided around the motor rotor 42 and fixed to the inner peripheral surface of the stator frame 37. , is housed within the pump casing 31.

Reference numeral 44 denotes a rotating body having rotor blades 45 opposed to the front silent blades 34, which is provided on the same axis as the drive mechanism 41, and is
It is fixed to the rotating shaft 40 by a port 45. Reference numeral 46 denotes a lifting prevention member facing between two rotor blades near the discharge side of the rotor blades 45, and is
It is located within 1. In other words, the lifting prevention member 46 is formed by the stator blade near the discharge side of the stator blade 34. Then, the rotating body 44
is configured to restrict axial movement of. The axial dimensions G, G2 between the lifting prevention member 46 and the rotor blade 45 are smaller than the axial dimensions S+, St between the other rotor blades 45 and the stationary blades 34 (G+ < s, , Gz<Sz). Further, it is desirable that the lifting prevention member 46 and the rotor blade 45 facing the lifting prevention member 46 be made of a wear-resistant material, or that the surfaces thereof be subjected to wear-resistant treatment. 47 is a discharge pipe fixed to the support body 36 and communicates with the inside of the pump casing 31, and 48 is a lubricating oil.

In the turbo-molecular pump configured in this manner, the movement stroke of the rotating body 44 in the axial direction can be set to a predetermined movement stroke by the lifting prevention member 46 on the discharge side of the pump casing during abnormal operation.

Therefore, in this embodiment, the stationary blades 34 and the moving blades 45
This eliminates the need for an expensive ring with a sealing function as in the past.

Further, in this embodiment, the ring is not required on the suction side of the pump casing 31, which is conventionally required, and a sufficiently large opening can be formed on the suction side of the casing.

Note that the anti-lifting member 46 in the present invention needs to be formed in an annular shape in order to have an exhaust function, but in order to simply restrict the movement of the rotating body 44 in the axial direction, it is necessary to form it in an annular shape as shown in FIG. 3(a).
As shown in FIG. 4(b) and FIG. 4, there is no problem in using half-shaped lifting prevention members 51 and 52.

Further, it goes without saying that the thicknesses of the anti-lifting member 46 and the rotor blade 45 in the present invention are not particularly limited.

〔Effect of the invention〕

As explained above, according to the present invention, among the stator vanes arranged in multiple stages in parallel in the axial direction, the stator vanes near the discharge side are formed by a lifting prevention member that restricts the axial movement of the rotating body, and the lifting prevention member Since the rotor blades face between two mutually adjacent rotor blades, the movement stroke in the axial direction of the rotating body can be set to a predetermined movement stroke by the lifting prevention member on the casing discharge side in the event of an abnormal operation.

Therefore, collision between the stationary blade and the rotor blade can be prevented, so that an expensive ring with a sealing function as in the conventional case is not required, and costs can be reduced. Furthermore, since a ring is not required on the suction side of the casing, which was required in the past, a sufficiently large opening can be formed on the suction side of the casing, so that the pump's exhaust performance can be improved.

[Brief explanation of drawings]

1 and 2 are cross-sectional views showing the entire turbomolecular pump and essential parts of the present invention, and FIGS. 3(a) and 3(b) show a lifting prevention member of a turbomolecular pump in another embodiment. A plan view and a side view, FIG. 4 is a plan view showing another lifting prevention member, and FIG. 5 is a sectional view showing a conventional turbo molecular pump. 31... pump casing, 32..., suction port,
33...Discharge port, 34...Stator blade, 40...
Rotating shaft, 41... Drive mechanism, 44... Rotating body,
45... Moving blade, 46... Lifting prevention member. Agent Masuo Oiwa Figure 2 L ('1 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] A casing that has stator blades arranged in parallel in multiple stages in the axial direction and opens on the suction side and the discharge side, a rotary shaft that is rotatably provided within the casing and rotates by a drive mechanism, and a rotary shaft that is fixed on the rotary shaft. and a rotor having rotor blades facing the stator blades,
Among the stator blades, the stator blade near the discharge side is formed by a lifting prevention member that restricts the axial movement of the rotating body, and the lifting prevention member is arranged to face between two mutually adjacent moving blades. Characteristic turbo molecular pump.