JPS5993993A - Rotor for turbo molecular pump - Google Patents

Abstract

PURPOSE:To provide a high efficiency turbo molecular pump, light in weight and with lesser deformation, by fixing a substantially disc shaped member to a hollow rotor across the revolving center of the rotor. CONSTITUTION:A turbine blade is given a circular form, while a spacer 11 is a solid disc of metal. A hollow rotor with a plurality of said spacers 11 fastened as in a single piece by vacuum brazing does not give reason to the periphery of turbine blades 3 being elongated outward even under high speed rotation. Accordingly the exterior surfaces of the turbine blades 3 can be approached to the interior surface of the casing 1, to provided a reduced gap therebetween.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a rotor for a turbomolecular pump, and more particularly to an improvement in a hollow rotor.

[Prior art]

The structure of a turbomolecular pump having a hollow rotor was, for example, the following L-eel groove structure as shown in Japanese Patent Application Laid-open No. 1'i4 117919. FIG. 1 is a front view of a conventional turbomolecular pump, with a portion thereof cut away to show the internal structure, in which an inlet flange 2 is formed at the upper part of a casing l of the pump body. This suction port flange 2 and the container to be evacuated are connected with a gasket interposed therebetween. Inside the casing l there are a turbine blade 3 and a spacer 4 that have been processed and formed.
are laminated alternately and fixed and integrated by vacuum brazing or the like to form a hollow rotor. This hollow rotor is rotatably supported at two positions, upper and lower, by bearings (not shown), and lubricating oil is circulated and supplied from an oil sump 8 to these bearings through oil holes provided in the hollow rotor. There is.

Stator blades 5 are arranged alternately between adjacent turbine blades 3, and each stator blade 5 is separated by a spacer 6.
are alternately stacked and fixed to the inner surface of the casing 1. Near the oil sump 8 at the bottom of the casing 1 (this is where a cooling water inlet/outlet 9 for cooling the electric motor and lubricating oil is provided, and an intake gas exhaust pipe 10 is attached to the left side of the inlet/outlet 9). It is airtightly connected to a subsequent vacuum pump. Note that 7 is a power supply line connected to a built-in electric motor, and when energized, the hollow rotor rotates.

The turbo-molecular pump configured in this manner is energized from the power supply line 10 after evacuation is performed by the vacuum pump connected at the subsequent stage until the pump reaches almost the molecular region. The electric motor of the turbomolecular pump rotates at high speed by special high-frequency input, and rotates the hollow rotor to which the turbine blades 3 are attached at a speed of 10,000 to 60,000 times per minute. When the turbine blade 3 rotates at high speed in this manner, gas molecules between the turbine blade 3 and the stationary blade 5 arranged at an inclination in the opposite direction to the turbine blade 3 collide, and gas molecules flow into the suction 7 from the flange 2. The gas is sequentially moved downward and is discharged to the pump in the latter stage after achieving a high compression ratio using the multi-stage blade rows. That is, the inside of the container to be evacuated connected to the inlet flange 2 can be evacuated to a high vacuum state by this turbo-molecular pump.

! The turbo-molecular pump shown in Figure 1 consists of a hollow rotor made by alternately stacking annular turbine blades 3 and small-diameter annular spacers 4 and integrating them by vacuum brazing. When this happens, the centrifugal force causes the turbine blades 3 to deflect outward. Therefore, in consideration of this deformation, the gap between the inner surface of the pump casing and the inner surface of the pump casing had to be increased, which reduced pump performance accordingly. As a countermeasure for this, if the turbine blades 3 were made thicker, the weight of the rotor would increase, resulting in an increase in power consumption.

[Purpose of the invention]

It is an object of the present invention to overcome the above-mentioned drawbacks of the prior art and to provide a rotor for a thin molecular pump that is lightweight, has little deformation, and is highly efficient.

[Summary of the invention]

The present invention resides in that a substantially disk-shaped member is fixed to the hollow rotor across the center of rotation of the hollow rotor.

1ζ Generally, the efficiency of a turbine molecular pump is determined by the rotational mass GD'' value of its rotor, so a hollow rotor that is light and has a small diameter will save power consumption.

However, with such a small diameter, the hollow rotor deforms during high speed rotation, so the hollow rotor must be strengthened to prevent sagging. For this purpose, a substantially disk-shaped member is provided that crosses the center of rotation of the hollow rotor. Note that this disc-shaped member is not limited to a solid metal disc, but may be a metal disc with holes as long as it provides mechanical strength.

[Embodiments of the invention]

FIG. 2 is a plan view of a rotor that is an embodiment of the present invention.
Figure f13 is a sectional view taken along line A-B in Figure 2. The same parts as in FIG. 1 are given the same reference numerals. Turbine R in this case
3 has an annular shape as in the case of FIG. 1, but spacer 1
1 is a solid metal disk. Spacer 1 like this
1 provided in a plurality of locations and vacuum-brazed together, the outer periphery of the turbine blade 3 is unlikely to extend outward due to centrifugal force even when rotated at high speed. Therefore, the outer diameter of the turbine blade 3 can be brought closer to the inner surface of the casing l to reduce the gap therebetween and improve exhaust efficiency.

Also, since the number of solid spacers 11 is approximately 14 of the total spacers, the weight of the hollow rotor does not increase significantly.

FIG. 4 is a plan view of a rotor according to another embodiment of the present invention.
FIG. 5 is a sectional view taken along the line C-D of the 1TlJ diagram.

In this case, after stacking a plurality of annular disks 12 (turbine R) with a thick inner diameter 1) 1, a thin disk spacer 15
holes are provided at four locations in the annular disk 12 and the disk spacer 15, and bolts 13 and nuts 14 are inserted.
It is fastened together and constituted as one piece. As in the case of Fig. 2, since the hollow rotor has multiple solid parts intervening, expansion deformation of the outer diameter is suppressed even during high-speed operation, and the same advantages as in the case of Fig. 3 can be obtained. .

FIG. 6 is a sectional view of a rotor that is a modification of the rotor shown in FIG. 3. In this case, instead of the disk spacer 11, a disk-shaped turbine JFt16 with turbine blades attached around the disk spacer is interposed.

FIG. 7 is a sectional view of a rotor that is a modification of FIG. 5, in which a solid disc-shaped turbine blade 17 is used instead of the disc spacer 150. That is, in this case, the spacer is omitted and the bolt 13. which is the member containing the two types of turbine IAs is used.
It is assembled into one body with 14 nuts.

FIG. 8 is a sectional view of a rotor according to another embodiment of the present invention. In this case, a machined hollow rotor 18 has a plurality of turbines R3 protruding from the cylindrical side surface of one hollow cylindrical body.
It becomes. That is, it is obtained by machining a single large-diameter round bar, and the hollow rotor is prevented from deforming by the end plate 19 at the end. The center hole of the end plate 19 is not large enough to reduce the strength of the rotor, and has substantially the same strength as the hollow disk.

Since the hollow rotors shown in FIGS. 2 to 8 have a solid disk or a substantially solid disk portion, deformation of the rotor during high-speed rotation can be prevented. Therefore, it becomes possible to reduce the gap with the turbine casing and improve the capacity.

The rotor for a turbomolecular pump provided with the solid disk portion 1 of this embodiment can reduce the gap between the turbine blade and the inner surface of the casing, resulting in improved pump performance and reduced power consumption. It will be done.

In all of the above embodiments, deformation during rotation of the hollow rotor is prevented by providing a plurality of solid disk portions, which apparently increases the rigidity. Therefore, the thickness of the hollow rotor can be reduced and the weight can be made lighter, so that power consumption can be further reduced. Generally, since turbomolecular pumps are operated continuously for long periods of time, the energy saving effect of power saving is significant.

〔Effect of the invention〕

The rotor for a turbomolecular pump according to the present invention can be made to have an efficient structure by preventing deformation during high-speed rotation by a relatively simple improvement of providing solid disk portions at multiple locations on the hollow rotor. Effects can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a front view of a conventional turbomolecular pump, Fig. 2 is a plan view of a rotor which is an embodiment of the present invention, Fig. 3 is a sectional view taken along line A-B in Fig. 2, and Fig. 4 is a diagram of the present invention. FIG. 5 is a sectional view taken along line CD in FIG. 4, and FIG. 6 is a sectional view of a rotor that is a modification of FIG. 3. FIG. 87 is a sectional view of a rotor that is a modification of FIG. 5, and FIG. 8 is a sectional view of a rotor that is another embodiment of the present invention. l...Casing, 2...Suction port 7 lange, 3...Turbine R, 4, 6, 11...
...Spacer, 5...Shizuko, 7...Power line, 8...Oil sump, 9...Cooling water inlet/outlet section, 10...・Discharge pipe, 12... Annular disc, 13... Bolt, 14... Bent nut, 15
... Disc spacer, 16.17... Disc-shaped turbine blade, 18... Machined hollow rotor, 19... End plate engineer 10 f2 figure f4 figure

Claims (1)

[Claims] 1. A casing with a plurality of stator blades attached at predetermined intervals on the inner surface of a cylinder, and a plurality of turbine blades each inserted between the stator blades, 1. A rotor for a turbo-molecular pump having a rotating hollow rotor, characterized in that a substantially disk-shaped member is fixed to the hollow rotor across the center of rotation of the hollow rotor. 2. The rotor for a turbomolecular pump according to claim 1, wherein the substantially disk-shaped member is a disk-shaped spacer interposed between the annular turbine blades. 3. The rotor of a turbomolecular pump according to claim 1, wherein the substantially disk-shaped member is a disk around which the turbine blade is fixed. 4. The rotor for a turbo-molecular pump according to claim 1, wherein the substantially disk-shaped member is an end plate that seals the cylindrical body forming the turbine blade except for the center portion thereof. .