JPH0610477B2 - Turbo vacuum pump - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a turbo vacuum pump, and more particularly to a compact and high performance turbo vacuum pump.

[Conventional technology]

Conventional turbo vacuum pumps generally use axial flow vanes that have excellent exhaust performance in the molecular flow region. On the other hand, in recent years, turbo vacuum pumps using a plurality of stages of circumferential flow blades that can obtain a large compression ratio in a viscous flow region have been proposed, for example, in Japanese Patent Laid-Open Nos. 62-29796 and 62-29797.

In the turbo molecular pump described in Japanese Patent Laid-Open No. 62-29796, the stator that forms the ventilation passage has a half-divided structure in order to allow the stator to enter inside the tip diameter of the rotor blade. The turbo molecular pump described in Japanese Patent Laid-Open No. 62-29797 is provided with a rotor having circumferential flow vanes in a stator which is not a half structure.

[Problems to be Solved by the Invention]

In the above-mentioned Japanese Patent Laid-Open No. 62-29796, since the stator has a half-divided structure, the number of parts increases and the assemblability is not good. Further, the one disclosed in JP-A-62-29797 has good assemblability, but since it is necessary to form a seal portion along the axial direction on the outer peripheral surface of the rotor, the axial length of the pump becomes large and the compactness is good. Not.

As described above, the conventional technology does not consider both aspects of compactness in manufacturing, and if it is compact, there is a problem in manufacturability, and if the manufacturability is good, it is not compact. Atsuta

An object of the present invention is to provide a turbo vacuum pump which is excellent in manufacturability and assemblability because it is not necessary to make a rotor having a circumferential flow blade and a stator having a ventilation passage into a half-split structure.

[Means for Solving the Problems]

The object is a casing having an intake port and an exhaust port, a rotary shaft rotatably supported in the casing, a rotor that is supported by the rotary shaft and constitutes a multi-stage circumferential flow vane, and the circle in the casing. In a turbo vacuum pump comprising a stator forming a multi-stage circumferential flow pump together with the circumferential flow vanes, the outer diameter of the rotor portion forming the multi-stage circumferential flow vane is based on the first stage circumferential flow vane from the intake port toward the exhaust port. It is formed so as to monotonically decrease or increase in the axial direction of the rotating shaft, and a slit seal part is provided between the end face of the rotor between each circumferential flow blade stage and the end face of the stator opposite to this, and this slit seal part Is formed so that the extension of the end face of each step intersects with the rotor axis (that is, the gap seal portion is formed with the end face parallel to (or intersecting) the radial direction with respect to the rotor axis). In particular Yotsute, it is achieved.

[Action]

By forming the outer diameter of the rotor having the circumferential flow vanes and the inner diameter of the stator to monotonically decrease or increase, it is not necessary to make the rotor having the circumferential vanes and the stator having the ventilation passage a semi-cracked structure. Good assemblability.

〔Example〕

 Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention. In FIG. 1, a rotor 1 is arranged in a casing 2 and shrink-fitted in a shaft 3. The outer diameter of the rotor 1 is monotonically reduced stepwise in the axial direction of the shaft 3 from the intake port 4 to the exhaust port 5 with reference to the first stage circumferential flow vane. A circumferential flow vane 6 is provided at the tip of each diameter. A stator 8 is supported on the base 7 so as to face the rotor 1. The inner diameter of the stator 8 gradually decreases in a stepwise manner in the axial direction of the shaft 3 as the outer diameter of the rotor 1 changes. An air passage 9 is provided on the inner diameter surface of the stator 8 that faces the circumferential flow vanes 6. A partition portion 10 is provided at one location in the circumferential direction of the stator 8 as shown in FIG. A suction port 11 is provided before and after the partition 10.
1 and a discharge port 12 are provided. End faces 1A of rotors 1 of different diameters and end faces 8A of stators 8 of different diameters facing the end faces 1A.
A slit seal portion 3 extending in the direction perpendicular to the rotor axis is formed between and. The shaft 3 is supported by the ball bearing 14 of the base 7 and the ball bearing 15 of the lower base 16. Lubrication of the bearing is performed by a self-contained structure in which oil 18 stored in an oil tank 17 is sucked up by a conical tubular body 19 and is supplied to the bearings 14 and 15 through the inside of the shaft 3. The rotor 1 is driven by a high-frequency motor rotor 20 and a rotor casing 2 that are shrunk in the shaft 3.
It is driven at a high speed by the high-frequency motor stator 22 supported by No. 1.

Next, the operation of the above-described embodiment of the present invention will be described.

When the rotor 1 is driven at high speed, the gas is exhausted from the intake port 4 to the exhaust port 5 by the action of the circumferential flow vanes 6. In order to effectively perform this exhaust action, it is necessary to reduce the leakage between the stages, but in this embodiment, the rotor 1 and the stator 8 having different diameters are used.
On the end face of the seal, that is, on the face perpendicular to the rotor axis.
Since the pump is provided, the inter-pump leakage can be reduced by the action of the seal portion 13. Therefore, it is not necessary to provide a seal portion in the axial direction between the pump stages, and the pump axial length can be shortened. As a result, the length in the axial direction of the pump can be shortened, and as a result, high-speed rotation can be facilitated and the performance of the impeller can be improved. Further, in this embodiment, the outer diameter of the rotor 1 is reduced from the intake port 4 side to the exhaust port 5 side, so that there is an advantage that the disc friction loss is reduced and the motor capacity can be selected small.

FIG. 3 shows another embodiment of the present invention. In this figure, the same symbols as in FIG. 1 are the same parts. In this embodiment, the outer diameter of the rotor 1'and the inner diameter of the stator 8'are formed so as to increase monotonically in the axial direction of the shaft 3 from the intake side to the exhaust side. According to this embodiment, as compared with the embodiment shown in FIG. 1, the disc friction loss of the rotor 1'becomes larger, which is not advantageous in terms of motor capacity, but the slit seal portion 13 'has no effect. Since the pumping action is exerted by the centrifugal force of the rotor 1 ', the sealing effect is better than that of the seal portion 13 of the embodiment shown in FIG. 1, and other than that, the same effect as the embodiment shown in FIG. 1 is obtained. .

FIG. 4 shows another embodiment of the present invention.
In this figure, the same parts as those in FIG. 1 are the same parts. In the embodiment shown in FIG. 1, a centrifugal pump having a centrifugal rotor 26 and a centrifugal stator 27 is provided on the intake side, and an axial flow rotor 28 and an axial flow stator 29 are provided on the intake side of the centrifugal pump. Is provided with an axial flow pump.

With this configuration, the intake port 4 can be made to have a higher vacuum than the embodiment shown in FIG. 1 by the exhausting action of the centrifugal pump and the axial flow pump, so that it is possible to exhaust from the atmospheric pressure to the high vacuum with one pump. Becomes In this way, when the blades of the other exhaust principle are stacked on the intake side of the circumferential flow blade 6, the circumferential flow pump stage is compact in the axial direction and has a high compression ratio, which means that the other exhaust principle is used. In addition to the effect of reducing the number of stages of the blade of, it can also facilitate high-speed rotation,
This is an effective advantage in terms of performance.

In the above description, the centrifugal pump is used as one provided on the intake side of the circumferential flow vane 6, but a thread groove pump may be used instead of the centrifugal pump.

It should be noted that in the above-described embodiment, the slit seal portions 13, 1 are
Although 3'is provided in the direction orthogonal to the rotor axis, it may be provided so as to intersect with the radial direction orthogonal to the rotor axial flow, as shown in FIG. Furthermore, this slit seal part 1
It is also possible to provide a labyrinth seal 30 or a thread groove as shown in FIG. 6 on at least one surface constituting 3, 13 '. By installing this sealing means, it is possible to further reduce the leakage between the pump stages and further improve the performance of the circumferential flow vane. Further, as shown in FIG. 7 and FIG. 8, a core 30 is provided in the ventilation passage 9 constituting the circumferential flow pump stage so as to effectively form a vortex of the flow in the ventilation passage 9. Good.

〔The invention's effect〕

According to the present invention, the outer diameter of the rotor having the circumferential flow blades and the inner diameter of the stator are formed so as to monotonously decrease or increase in the axial direction of the rotating shaft, so that the rotor and the stator do not need to have a half-split structure. Therefore, the manufacturability and the assemblability are good.

[Brief description of drawings]

1 is a longitudinal sectional view of an embodiment of the present invention, FIG. 2 is a lateral sectional view of FIG. 1, and FIG. 3 is a reduced sectional view of another embodiment of the present invention.
FIG. 4 is a vertical cross-sectional view of another embodiment of the present invention, FIGS. 5 and 6 are vertical cross-sectional views showing an embodiment of a slit seal portion constituting the present invention, and FIG. 7 is a book. FIG. 8 is a cross sectional view showing another example of the circumferential flow pump stage constituting the invention, and FIG.
It is a VIII-VIII sectional view of the figure. 1 ... Rotor, 2 ... Casing, 3 ... Shaft, 4
...... Intake port, 5 ... Exhaust port, 6 ... Circumferential blade, 7 ... Base, 8 ... Stator, 9 ... Ventilation passage, 10 ... Partitioning section, 11 ... Suction port, 12 ... Discharge port , 13, 13 '...
... Slit seal part, 14,15 ... ball bearing, 16 ... lower base, 17 ... oil tank, 18 ... oil, 19 ... conical tubular body, 20 ... motor rotor, 21 ... motor casing, 22 ... Motor stator, 25 ... Labyrinth, 26 ... Centrifugal rotor, 27 ... Centrifugal stator, 28
...... Axial rotor, 29 ...... Axial stator, 30 ...... Core.

Front page continuation (72) Inventor Seiji Sakagami 502 Jinritsu-cho, Tsuchiura-shi, Ibaraki Machinery Research Institute, Hitate Manufacturing Co., Ltd. (56) References JP-A 61-247893 (JP, A) JP-A 61-87996 (JP, A) JP-A 61-31695 (JP, A)

Claims (6)

[Claims] 1. A casing having an intake port and an exhaust port, a rotating shaft rotatably supported in the casing, a rotor which is supported by the rotating shaft and constitutes a multi-stage circumferential flow blade, and a casing which is provided in the casing. In a turbo vacuum pump comprising a stator forming a multistage circumferential flow pump together with the circumferential flow vanes, an outer diameter of a rotor portion constituting the multistage circumferential flow vane, with reference to the first stage circumferential flow vane in the direction from the intake port to the exhaust port. Are formed so as to monotonically decrease in the axial direction of the rotating shaft, and a slit seal portion is provided between the end surface of the rotor between the circumferential flow blade stages and the end surface of the stator facing the slit gap portion. Is a turbo vacuum pump characterized in that the extension of the end face of each stage intersects the rotor axis. 2. A turbo vacuum pump according to claim 1, wherein a labyrinth is provided on at least one surface forming the slit seal portion. 3. The turbo vacuum pump according to claim 1, wherein a thread groove is provided on at least one surface forming the slit seal portion. 4. A casing having an intake port and an exhaust port, a rotating shaft rotatably supported in the casing, a rotor which is supported by the rotating shaft and constitutes a multi-stage circumferential flow blade, and the casing having the casing. In a turbo vacuum pump comprising a stator forming a multistage circumferential flow pump together with the circumferential flow vanes, an outer diameter of a rotor portion constituting the multistage circumferential flow vane, with reference to the first stage circumferential flow vane in the direction from the intake port to the exhaust port. Are formed so as to increase monotonically in the axial direction of the rotating shaft, and a slit seal portion is provided between the end surface of the rotor between the circumferential flow blade stages and the end surface of the stator opposite thereto, and the slit seal portion is A turbo vacuum pump, wherein the extension of the end face of each stage is formed so as to intersect the rotor axis. 5. The turbo vacuum pump according to claim 4, wherein a labyrinth is provided on at least one surface constituting the slit seal portion. 6. The turbo vacuum pump according to claim 4, wherein a thread groove is provided on at least one surface of the slit seal portion.