JPS60116896A - Vacuum pump - Google Patents

Abstract

PURPOSE:To cool heat due to friction loss by a method wherein a siegbahn molecular pump stage and a centrifugal compression pump stage, arranged with a small impeller, are provided continuously in a housing from a suction port side to a discharging port side in the vacuum pump. CONSTITUTION:The siegbahn molecular pump stage 10 and the centrifugal compression pump stage 11 are provided on the same shaft sequentially and continuously in the housing 2 from the suction port 2A to the discharging port 2B and are provided with a plurality of vanes 14 radially on the surfaces thereof. A proper clearance 18 is formed between a final stage 11An and a housing side wall 2C. GAS, compressed by both pumps, is sucked by the small vanes 6 while atmospheric air, passed through a filter 17, is sucked from a clearance 13 to cool the heat generated by the friction of the disc of an impeller 11An. According to this method, the heat, generated by the friction of the disc of the impeller, may be excluded even if the pressure in the exhaust stage is near the atmospheric pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention is applicable to applications ranging from a vacuum belonging to the viscous flow region to a vacuum belonging to the molecular flow region, that is, atmospheric pressure (760 Torr).
)) The present invention relates to a vacuum pump suitable for continuously performing an evacuation operation over a wide range of torque from around 10 −4 to around 10 −4 with a single drive source.

[Background of the invention]

The conventional vacuum pump (Japanese Patent Application Laid-Open No. 51-38113) was the first
As shown in the figure, it is provided symmetrically with respect to line I-1, and the structure of this right half is as follows. That is, fixed plates 3B to 6B attached to the inner wall of the housing 2 having an intake port 2A and an exhaust port 2B, and a rotating shaft l rotatably supported within the housing 2 via a bearing 7.
An axial flow turbomolecular pump stage 3, a Siegbahn molecular pump stage 4, a centrifugal compression pump stage 5, and a vortex compression pump stage 6, each consisting of a rotating disk 3A and impellers 4A to 6A attached to the They are arranged in series in the housing 2 up to the exhaust port 2B side.

The axial flow turbomolecular pump stage 3 is constructed by alternately combining the rotating plate 3Δ and the fixed plate 3B, and the sieve burn molecular pump stage 4 is composed of the disc-shaped impeller 4A and the fixed plate 4B.
The centrifugal compression pump stage 5 is constructed by alternately combining the impeller 5A and the diffuser fixing plate 5B, and the vortex compression pump stage 6 is composed of the impeller 6A and the fixing plate 6B. They are composed of alternating combinations.

On the other hand, the rotating shaft 1 is driven through a drive turbine 8, and the drive turbine 8 communicates with an air outlet 9A and an air outlet 9B provided on the side wall of the housing 2.

In the conventional vacuum pump described above, fluid is sucked from a closed chamber (not shown) through the intake port 2A, and the fluid is pumped through each of the pump stages 3 to 3.
When the exhaust gas is discharged into the atmosphere from the exhaust port 2B through the pump 6, the exhaust gas becomes dense and becomes a viscous fluid due to the compression action of the pump stage.

In the vortex compression pump stage 6, the pressure increases due to rotational motion, but at this time, disc friction loss occurs in the impeller 6A.

In the viscous flow region, the disk friction loss is as described in (1) above.
It is expressed by the formula.

711L=CMζw”D”/64 ・−・・(1)
However, C1: Constant that varies depending on the Reynolds number ζ: Fluid density (K g / rri') W: Angular velocity of the rotating disk (γad/s) D Diameter of the two-rotating disk (m) From the above equation (1) It can be seen that the disk friction loss power increases in proportion to the fifth power of the rotating disk. On the other hand, the pressure of the vortex compression pump stage 5 increases in proportion to the square of the diameter of the vortex impeller 6Δ and the square of the rotational speed.

In order to increase the compression ratio of the vortex compression pump stage 6, the rotational speed of the pump stage 6 must be increased or the diameter of the vortex impeller 6A must be increased.

However, since the upper limit of the rotational speed of the rotating shaft 1 is determined by the critical speed limit of the rotating shaft 1, the diameter of the vortex impeller 6A must be increased.

When the diameter of the vortex impeller 6A is increased in this way, the disk friction loss increases, so the drive device has the disadvantage of increasing the capacity.

Also, by the stage before the vortex compression pump stage 6, the fluid has been considerably compressed, so that the volumetric flow rate is small. Therefore, since the transfer of heat generated by the disk friction of the swirl impeller 6A is small, there is a drawback that cooling is difficult.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a vacuum pump which can eliminate the following drawbacks of the conventional vacuum pump by using an extremely simple structure.

[Summary of the invention]

In order to achieve the objectives of "2.1", the present invention includes a fixed disk or stator vane attached to the inner wall of a housing having an intake port and an exhaust port, and a stationary vane attached to a rotating shaft rotatably supported within the housing. A sieve burn molecular pump stage or Φ+I+ flow molecular flow molecular pump stage consisting of a 1-keeled rotary disk or rotor blade, or a 21st stage consisting of a fixed disk attached to the inner wall of the housing and an impeller attached to the rotating shaft. In a vacuum pump comprising centrifugal compression pump stages successively arranged in a housing from the suction port side to the discharge port side, an arbitrary number of small The present invention is characterized in that the blades are arranged radially, and a gap is appropriately formed in the housing penetrating portion of the rotating shaft.

[Embodiments of the invention]

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

FIG. 2 shows a cross section of this embodiment, which is arranged symmetrically with respect to the I-1 line, and the structure of the right half is as follows.

In FIG. 2, reference numeral 1 denotes a rotating shaft that passes through a housing 2 having an intake port 2A and an exhaust port 2B, is rotatably supported by a bearing 7, and one end thereof is connected to a drive device (not shown). . A suitable gap 13 is formed in the passage of the rotating shaft 1 through the housing side wall 2C, and a filter 17 is attached to the atmosphere side of the gap 13, that is, to the outer surface of the housing side wall 2G.

A Siegpern molecular pump stage 10 and a centrifugal compression pump stage 11 are successively arranged in the housing 2 from the intake port 2A side to the exhaust port 2B side. That is, the Siegbahn molecular pump stage IO is constructed by alternately arranging rotating disks 10A attached to the rotating shaft 1 and fixed disks 10B attached to the inner wall of the housing 2.

Moreover, as shown in FIG. 3(,)(b), the fixed disk 10B has a spiral groove 10BI on the surface facing the rotating disk (not shown) (the right surface in FIG. 3(,)). is provided.

Further, the centrifugal compression pump stage 11 is configured as shown in FIG.
), an impeller 11 has a plurality of blades 14 arranged radially on one surface and is attached to a rotating shaft l.
A and a surface that is attached to the housing 2 and faces the back surface of the impeller 11A (without the blades 14), as shown in FIG. 4(a).

Fixed plate 11B provided with a plurality of return channels 15
It is constructed by arranging them alternately. The impeller 11A
As shown in FIGS. 5(a) and 5(b), the last impeller 11An in the group has blades 14 radially provided on the front surface and small blades 16 radially provided on the back surface, similarly to the impeller 11A. There is. Needless to say, an appropriate gap 18 is created between the final impeller 11An and the housing side wall 2C.
is formed.

Next, the operation of this embodiment configured as described above will be explained.

Gas flows in through the intake port 2A and then into the helical groove 10J31 of the fixed plate 10B of the Siegbahn molecular pump stage 10. In this Siegbahn molecular pump stage 10, the gas is moved into the spiral groove by the drag action of the rotating disk 10A.
It flows in OB1 and flows into the spiral groove 10BI of the opposing fixed plate 1t)B. The gas flows from the Siegbahn molecular pump stage 10 to the centrifugal compression pump stage 11 by repeating this process. In this centrifugal compression pump stage 11, the gas is pressurized by the group of impellers 11, and at the same time is sequentially compressed AL and discharged into the atmosphere from the exhaust port 2B via the final impeller 11An.

In this case, the small blade J6 provided on the final impeller 11An
Therefore, the outside air that has passed through the filter 17 is passed through the gap 1 of the shaft penetration part.
Inhaled from 3. This intake outside air is supplied to the impeller 11A.
After cooling the heat generated by the disk friction of r+, the exhaust Ll 2 is discharged together with the gas flowing out from the centrifugal compression pump stage 11.
It is discharged from 13.

〔Effect of the invention〕

As explained above, according to the present invention, the final impeller of the centrifugal compression pump stage has an extremely simple structure in which a small blade dedicated to cooling is provided, so that even if the pressure at the exhaust port is close to atmospheric pressure Heat generated by disc friction can be eliminated.

[Brief explanation of drawings]

Fig. 1 is a sectional view of a conventional vacuum pump, Fig. 2 is a sectional view showing an embodiment of the vacuum pump of the present invention, and Fig. 3 (aHb).
4 is a cross-sectional view and a side view of the fixing plate of the Siegbahn molecular pump stage of the same example, FIG. A cross-sectional view showing the final stage of the centrifugal compression pump stage of the same example, and (a)
It is a sectional view taken along the line m-III of FIG. ■... Rotating shaft, 2... Housing, 1o... Siegbahn molecular pump stage, IOA... Rotating disk or moving blade, 10B... Fixed disk or stator blade, 11... Centrifugal compression Pump stage, IIA... impeller, 11An... final impeller, 13... gap, 16... small impeller, 17.
··filter. Figure 3 (0″) (and). Yu, th’ia To I (4)

Claims (1)

[Scope of Claims] 1. A fixed disk or stator vane attached to the inner wall of a housing having an intake port and an exhaust port, and a rotating disk or vane attached to a rotating shaft rotatably supported within the housing. A Siegbahn molecular pump stage consisting of a rotor blade, or an axial flow molecular pump stage and a centrifugal compression pump stage consisting of a fixed disk attached to the inner wall of the housing and an impeller attached to the rotating shaft, on the intake port side. In a vacuum pump that is sequentially arranged in a housing from the to the exhaust port side, an arbitrary number of small blades are arranged radially on the back of the final impeller of the centrifugal compression pump stage, and the rotary shaft A vacuum pump characterized in that an appropriate gap is formed in the housing penetrating portion. 2. The vacuum pump according to claim 1, further comprising a filter provided on the atmosphere side of an appropriate gap formed in the housing penetrating portion of the rotating shaft.