JPH0759956B2 - Vacuum pump - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a vacuum pump.

(Prior Art) The oil-free hybrid vacuum pump made by Ceramics which the applicant of the present invention has already proposed will be described with reference to FIG.
(01a) is a multi-stage rotor blade, (01b) is a rotor having each rotor blade (01a), (01c) is a multi-stage stationary blade, (03) is a non-contact seal, (04) is an upper gas bearing, (06) is a lower gas bearing, (07) is a lowermost gas bearing, (08) is a gas bearing supply port, (05) is a gas turbine provided on the rotating body (01b), and (05a) is a gas turbine supply. Mouth, (0
14a) (014b) (014c) are casings of the turbo molecular pump and the thread groove vacuum pump.
4) The moving blades (01a) and the rotating body (10b) are rotatably supported in the casings (014a) and (014b) by (06) and (07). Next, a screw groove vacuum pump for low vacuum will be described. (02) is a rotating body, (013) is a hollow stationary body having a screw groove, (09) is an upper gas bearing, and (01
1) is a lower gas bearing, (012) is a lowermost gas bearing, (010) is a gas turbine provided on the rotating body (02), (010a) is a gas turbine inlet port, and each of the gas bearings (09) is The rotating body (02) is rotatably supported in the casings (014b) and (014c) by (011) and (012).

Next, the operation of the ceramic oil-free hybrid vacuum pump shown in FIG. 3 will be described. The rotor blade (01a) and rotor (01b) of the high vacuum turbo molecular pump are rotated at high speed by the gas turbine (05), and the rotor (02) of the thread groove vacuum pump for low vacuum is rotated by the gas turbine (010) at high speed. Rotate and evacuate in the direction of arrow (A ₁ ) → (A ₂ ) → (A ₃ ) to generate a high vacuum on the (A ₁ ) side. At this time, (A ₃ )
On the side, exhaust is performed at a pressure near atmospheric pressure. Further, the turbine air supply (B ₁ ) supplied to the gas turbine (05), the turbine air supply (B ₂ ) supplied to the turbine (010), and the gas bearings (04) (06) (07) and (09) (011) The bearing air supply (B ₃ ) supplied to (012) is indicated by the arrow (C ₁ ) → (C ₂ ) → (C ₃ ) →
Discharge in the direction of (C ₄ ), and finally merge with the above (A ₃ ),
Discharge to the outside of the pump.

(Problems to be Solved by the Invention) In the ceramic-free oil-free hybrid vacuum pump shown in FIG. 3, a non-contact seal provided between the exhaust side (P) of the turbo molecular pump and the upper gas bearing (04). The axial length of (03) cannot be made sufficiently long because of the need to improve the rotational performance, and the compression ratio becomes small in combination with the fact that the seal (03) is not in contact, and the exhaust side (P )
To the intake side (Q) due to an increase in the amount of leakage to the exhaust side (P) and a decrease in the compression ratio of the turbo molecular pump.
However, there was a problem that the ultra high vacuum could not be obtained due to the high pressure.

The present invention is proposed in view of the above problems, and an object of the present invention is to provide a vacuum pump capable of obtaining an ultrahigh vacuum.

(Means for Solving the Problems) In order to achieve the above object, the present invention is directed to a ceramic rotating body having multi-stage rotor blades, a gas bearing for rotatably supporting the rotating body, and the rotating body. A turbo molecular pump equipped with a gas turbine, and a hollow stationary body having a thread groove on the inner peripheral surface, a rotor made of ceramics inserted in the hollow stationary body, and a gas bearing that rotatably supports the rotor. A vacuum pump having a thread groove vacuum pump equipped with a gas turbine for driving a body, wherein the turbo molecular pump and the thread groove vacuum pump are separately provided in a casing, wherein an exhaust side of the turbo molecular pump and a gas are provided. A gas bearing side of a seal provided between the bearing and the bearing is connected to an intermediate stage of the thread groove vacuum pump by an exhaust hole provided in the casing.

(Operation) The present invention provides a turbo molecular pump including a ceramic rotating body having multi-stage rotor blades, a gas bearing rotatably supporting the rotating body, and a gas turbine driving the rotating body, and A thread groove having a hollow stationary body having a thread groove on its inner peripheral surface, a ceramic rotating body inserted into the hollow stationary body, a gas bearing rotatably supporting the rotating body, and a gas turbine driving the rotating body. Has a vacuum pump,
A vacuum pump in which the turbo molecular pump and the thread groove vacuum pump are separately provided in a casing, wherein a gas bearing side of a seal provided between an exhaust side of the turbo molecular pump and a gas bearing and the thread groove vacuum pump The intermediate stage of is communicated with the exhaust hole provided in the casing,
The pressure on the high-pressure side of the seal decreases, the amount of leakage to the high-vacuum side decreases, and it is possible to directly evacuate from the high-vacuum region to the atmosphere (or the low-vacuum region) to obtain an ultra-high vacuum.

(Embodiment) Next, a vacuum pump of the present invention will be described with reference to an embodiment shown in FIG. First, the turbo molecular pump side for high vacuum will be described. (1a) is a multi-stage rotor blade, and (1b) is each rotor blade (1
Rotor with a), (1c) multi-stage vanes, (3) non-contact seal, (4) upper gas bearing, (6) lower gas bearing, (7) lowermost gas bearing,
(8) is a gas bearing air supply port, (5) is a gas turbine provided in the rotating body (1b), (5a) is a gas turbine air supply port, (14a) (14b) (14c) is a turbo molecular pump and In the casing of the thread groove vacuum pump, the rotor blades (1a) and the rotor (1b) are rotatably supported by the gas bearings (4) (6) (7) in the casings (14a) (14b). Has been done. Next, the thread groove vacuum pump for low vacuum will be described. (2) is a rotating body, (13) is a hollow stationary body having a thread groove, (9) is an upper gas bearing, (11) is a lower gas bearing, and (12) ) Is the bottom gas bearing,
(10) is a gas turbine provided on the rotating body (2), (10
a) is a gas turbine of turbo molecular pump for high vacuum (5)
And the gas turbine (10) of the low groove screw groove vacuum pump for connecting the gas turbine (10) with an exhaust port of the gas turbine (5) (10). The rotating body (2) is rotatably supported in the casings (14b) and (14c) by 11 and (12).
Further, (15) is the most characteristic exhaust hole of the present invention, the exhaust hole (15) is provided in the casing (14c), and the non-contact seal (3) provided on the exhaust side of the turbo molecular pump is provided. The gas bearing (4) side and the intermediate stage of the thread groove vacuum pump are connected by the same exhaust hole (15).

Next, the operation of the vacuum pump shown in FIG. 1 will be specifically described. The rotor blade (1a) and rotating body (1b) of the high vacuum turbo molecular pump are rotated at high speed by the gas turbine (5), and the rotating body (2) of the thread groove vacuum pump for low vacuum is rotated by the gas turbine (10) at high speed. Rotate, arrow (A ₁ ) → (A ₂ ) →
Evacuate in the (A ₃ ) direction to generate a high vacuum on the (A ₁ ) side. At this time, the (A ₃ ) side exhausts at a pressure near atmospheric pressure. Also, the non-contact seal (3) is evacuated from the gas bearing (4) side of the non-contact seal (3) through the exhaust hole (15) to the intermediate stage of the thread groove vacuum pump for low vacuum (see (D ₁ )). The bearing side pressure (P ₁ ) of the high vacuum turbo molecular pump is reduced to reduce the amount of leak to the high vacuum side, and the exhaust side pressure (P ₂ ) of the high vacuum turbo molecular pump is reduced, thereby increasing the intake of the high vacuum turbo molecular pump. The side pressure (P ₃ ) is lowered to generate a higher high vacuum on the (A ₁ ) side. Further, the gas turbine (5) of the turbo molecular pump for high vacuum and the gas turbine (10) of the thread groove vacuum pump for low vacuum are connected by the turbine air supply port (10a). ing. The gas turbine charge (B ₁ ) flows in the direction of the turbine (5) → arrow (C ₁ ) → turbine (10) → arrow (C ₂ ), and the bearing charge (B ₃ ) flows in the direction of arrow (C ₃ ) → Flows in the direction of (C ₄ ), and finally merges with the above (A ₃ ) and is discharged outside the pump.

Figure 2 shows the hollow stationary body of the thread groove vacuum pump (13a) (1
This is another embodiment in which the gas turbine (5) is also used as the thrust disk of the turbo molecular pump and the gas turbine (10) is also used as the thrust disk of the thread groove vacuum pump for low vacuum. In the example, gas turbine (5)
The blade diameter of (10) can be increased, the driving force can be increased, the rotation speed can be increased, and the exhaust performance can be further improved.

(Advantages of the Invention) The present invention provides a turbo molecular pump including a ceramic rotor having multi-stage rotor blades, a gas bearing rotatably supporting the rotor, and a gas turbine driving the rotor. , And a hollow stationary body having a thread groove on the inner peripheral surface thereof, a ceramic rotating body inserted into the hollow stationary body, a gas bearing rotatably supporting the rotating body, and a gas turbine driving the rotating body. Has a thread groove vacuum pump,
A vacuum pump in which the turbo molecular pump and the thread groove vacuum pump are separately provided in a casing, wherein a gas bearing side of a seal provided between an exhaust side of the turbo molecular pump and a gas bearing and the thread groove vacuum pump The intermediate stage of is connected to the intermediate stage by an exhaust hole provided in the casing, the pressure on the high pressure side of the seal is reduced, and the amount of leakage to the high vacuum side is reduced. Or it can be evacuated to a low vacuum region, and it is effective in obtaining an ultra-high vacuum.

Although the present invention has been described with reference to the embodiments, the present invention is not limited to such embodiments, and various design modifications can be made without departing from the spirit of the present invention.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view showing an embodiment of a vacuum pump according to the present invention, and FIG. 2 is a vertical sectional side view showing another embodiment.
FIG. 1 is a vertical sectional side view showing a conventional hybrid vacuum pump. (1a) …… Multi-stage rotor blade of turbo molecular pump, (1b) ……
Rotating body, (4) (6) (7) …… Gas bearing,
(5) …… Gas turbine, (2) …… Rotary body of screw groove vacuum pump, (9) (11) …… Gas bearing, (10)…
… Gas turbine, (13)… Hollow stationary body, (15)… Exhaust hole.

Claims (1)

[Claims] 1. A turbo molecular pump comprising a ceramic rotor having multi-stage rotor blades, a gas bearing rotatably supporting the rotor and a gas turbine driving the rotor, and a screw on the inner peripheral surface. A screw groove vacuum pump comprising a hollow stationary body having a groove and a gas bearing for rotatably supporting the rotor made of ceramics inserted in the hollow stationary body and the rotor and the gas turbine driving the rotor, A vacuum pump in which the turbo molecular pump and the thread groove vacuum pump are separately provided in a casing, wherein a gas bearing side of a seal provided between an exhaust side of the turbo molecular pump and a gas bearing and the thread groove vacuum pump A vacuum pump characterized in that the intermediate stage of the above is connected by an exhaust hole provided in the casing.