JPS609439Y2 - turbo molecular pump - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a turbo-molecular pump, and more particularly to a turbo-molecular pump in which a rotor having intake blades and a drive mechanism for driving the rotor are provided in the same pump body.

*Background technology This type of turbo-molecular pump has the advantage that the rotor and drive mechanism are provided within the same pump body, making its structure extremely compact. Since it is practically impossible to completely seal the spindle in the drive mechanism, it is not possible to completely seal the drive mechanism with the space inside the pump body, and as a result, the turbo Gases that are harmful to the drive mechanism, including corrosive gases and dust, which are inhaled by the molecular pump, flow into the drive mechanism, causing corrosion of each part of the drive mechanism or damage due to the incorporation of dust. This was a fatal problem for seed pumps.

Conventionally, as a means for preventing the harmful gas sucked in by such a turbo-molecular pump from flowing into the drive mechanism, there is a structure shown in FIG. 4.

That is, in the same figure, there is an inner peripheral surface 11 at the bottom of the rotor 8.
A small gap 10' is formed between the upper outer circumferential surface 6' of the drive mechanism section 2, and the drive mechanism section 2 has an injection hole 12 communicating with the outside of the pump body 13. The structure is such that a purge gas such as nitrogen supplied from a separately provided gas supply system 15 passes through the injection hole 12 and is filled into the drive mechanism section 2, and the filled purge gas is It passes through the inside of the drive mechanism section 2 and further includes the upper outer circumferential surface 6 of the drive mechanism section 2 and the inner circumferential surface 11 of the rotor 8.
The gap 10' formed by the gap 10'
Since the size of the pump body is small, the outflow velocity becomes high, and the water passes through and flows out into the pump body internal space 16'.

Therefore, the flow of the purge gas from inside the drive mechanism section 2 into the pump body internal space 16' conversely prevents harmful gases from flowing into the drive mechanism section 2 from the pump body internal space 16'. It is.

However, in this conventional system, the purge gas filled in the drive mechanism is simply caused to flow out into the space inside the pump body through a small-sized gap, so the outflow speed through the gap is reduced. In addition, if the pressure in the pump body space is higher than the purge gas pressure in the drive mechanism, gas inflow from the pump body space into the drive mechanism is completely prevented. It has the disadvantage that it cannot be used.

Moreover, the pressure in the internal space of the pump main body varies greatly depending on the amount of gas taken in and exhausted by the turbo-molecular pump.

Therefore, in the past, it was necessary to always fill the drive mechanism with a large amount of purge gas at high pressure in order to always measure the outflow of purge gas from the drive mechanism without being affected by the pressure in the internal space of the pump body. .

As a result, the conventional pumps are not only economical in the use of purge gas, but also because the total amount of purge gas flowing out into the pump body in large quantities and intake gas taken in by the turbo molecular pump itself is large. This poses various problems, including the need to increase the size of an auxiliary vacuum pump (not shown) that is separately connected to the exhaust port.

*Problems to be solved The purpose of this invention is to solve the problems mentioned above.
The simple structure, which is an improvement over the conventional one, completely prevents harmful gases from entering the drive mechanism, and also significantly reduces the amount of purge gas used.At the same time, the separately provided auxiliary vacuum pump is also miniaturized, making it economical. The object of the present invention is to provide a completely new and useful turbomolecular pump that is superior in terms of performance.

*Disclosure of the invention The present invention was constructed to distantly relate to this purpose, and its structure is to fill the drive mechanism section 2 with purge gas,
A gap 10 for allowing the filled purge gas to flow out into the inner space 16 of the pump body is formed on the outer circumferential surface 6 of the drive mechanism section 2.
In a turbo molecular pump formed by the inner circumferential surface 11 of the rotor 8, either the outer circumferential surface 6 of the drive mechanism section 2 forming the gap 10 and the inner circumferential surface 11 of the rotor 8. On the other hand, a spiral groove 7 is formed to discharge the purge gas inside the drive mechanism section 2 toward the pump body internal space section 16 side by the rotation of the rotor 8.

*Effects Since the present invention is configured as described above, it has the following effects.

■ A spiral groove is formed on either the outer circumferential surface of the drive mechanism forming the gap or the inner circumferential surface of the rotor so that the purge gas inside the drive mechanism is discharged to the pump body internal space side by rotation of the rotor. Therefore, the rotation of the rotor and the action of the spiral groove combine to compress the purge gas present in the gap and discharge it into the internal space of the pump body (ie, a screw pump action effect).

Therefore, since the purge gas discharged from the gap is always at a higher pressure than the internal pressure inside the drive mechanism, the inner space of the pump body is This has the special effect of completely preventing harmful gases from flowing into the drive mechanism section from the drive mechanism section.

As a result, there is no possibility that the harmful gases sucked in by the turbo-molecular pump will flow into the drive mechanism and corrode or damage the parts within the mechanism.

■ Also, since the present invention uses the aforementioned screw pump action to equalize a small amount of purge gas to high pressure and then discharge it,
The amount of purge gas discharged is very small compared to the conventional method in which the purge gas is directly discharged from the gap into the internal space of the pump body.

Therefore, the present invention can significantly reduce the amount of purge gas filled into the drive mechanism compared to the conventional method, and as a result, the cost of the purge gas can be significantly reduced.

■ Furthermore, since the amount of purge gas to be filled can be reduced as described above, the total amount of the purge gas and the intake gas taken in by the tarp molecular pump itself is significantly reduced compared to the conventional method, and as a result, the amount of the gas This has the advantage that the auxiliary vacuum pump for evacuating the air can be downsized.

As described above, the present invention has achieved various effects with a simple configuration in which a spiral groove is formed on either the outer circumferential surface of the drive mechanism part that forms the gap or the inner circumferential surface of the rotor. Ta.

*Example: Hereinafter, embodiments of the present invention will be explained according to examples shown in the drawings.

Figure 1 shows a turbomolecular pump according to the present invention, in which 1
1 shows a substantially bottomed cylindrical cover integrally fitted onto the upper part of the casing 3 of the drive mechanism section 2.

The inner circumferential surface 6 of the integral cover 1 is formed with a spiral groove 7 in a right-handed thread direction.

Reference numeral 8 indicates a rotor fixed to the upper part of the spindle 9. An inner circumferential surface 11 is formed at the lower part of the rotor 8 so as to have a slight gap 10 with the outer circumferential surface 6 of the cover unit 1.

12 is a lower surface portion 14 of the drive mechanism portion 2 and the pump body 13;
The injection hole 12 is connected to a purge gas supply system 15 such as nitrogen.

Reference numeral 16 indicates a space inside the pump body 13. To explain the function and effect of the embodiment with the above configuration, first, while introducing purge gas into the drive mechanism section 2 from the gas supply system 15 through the injection hole 12, the spindle 9 is moved in the right direction ( clockwise) to drive the rotor 8.

The purge gas introduced into the drive mechanism section 2 passes through the drive mechanism section 2 and reaches the front part of the gap 10 formed by the outer circumferential surface 6 of the cover unit 1 and the inner circumferential surface 11 of the rotor 8. do.

The purge gas that has reached the front part of the gap 10 enters the gap 10 while rotating in the same manner as the inner circumferential surface 11 of the rotor 8 due to its viscosity, and the purge gas is further formed on the outer circumferential surface 6 of the cover unit 1. The liquid is forcibly fed along the spiral groove 7 and discharged into the internal space 16 of the pump body.

The purge gas discharged at this time is at a higher pressure than when it is filled into the drive mechanism section 2, and moreover,
Since the pressure is set to be higher than that under any other situation, no harmful gas or the like from the pump body internal space 16 will flow into the gap 10.

Therefore, there is no inflow of harmful gas into the drive mechanism section 2.
It is always filled with purge gas, and each part functions normally without being damaged by corrosion or dust.

In the above embodiment, the spiral groove is formed integrally with the cover that is externally fitted and fixed to the casing of the drive mechanism part, and the manufacturing process for forming the spiral groove is facilitated. However, the shape of the cover integrally Not only is the invention not limited to this embodiment, but the integrated cover is not an essential requirement of the present invention, and if necessary, the casing 3 of the drive mechanism section 2 may be replaced without providing the integrated cover as shown in FIG. The spiral groove 7' may be formed directly on the upper outer circumferential surface 6'.

Further, the location where the spiral groove is formed is by no means limited to the drive mechanism section as described above, and as shown in FIG.
A spiral groove 7'' may be formed in the groove 7'.

Even with this configuration in which the spiral groove 7'' is formed on the rotor 8' side, the so-called screw pump action is exerted by the spiral groove 7'', and the purge gas is compressed and discharged.

As described above, the means and location for forming the spiral grooves are by no means limited to those in the above embodiments, and in short, the means and locations for forming the spiral grooves are either the outer circumferential surface of the drive mechanism forming the gap or the inner circumferential surface of the rotor. It is only necessary that a spiral groove be formed in the groove.

However, it is necessary to determine whether the spiral groove has a right-handed thread or a left-handed thread so that the purge gas can be discharged from the drive mechanism side to the space inside the pump body, taking into account the rotating direction of the rotor. By changing the shape of the purge gas, the pressure of the purge gas to be discharged can be arbitrarily changed.

The thin ice design is not limited to the configuration of each part of the turbo molecular pump itself, and the design can be changed as necessary.

Needless to say, the purge gas is not limited to nitrogen, but may be of any type as long as it does not contain corrosive dust or the like and does not have an adverse effect on the drive mechanism.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a turbomolecular pump showing an embodiment of the present invention. FIGS. 2 and 3 are sectional views of main parts of a turbomolecular pump showing other embodiments. FIG. 4 is a sectional view showing a conventional turbo molecular pump. 2... Drive mechanism part, 7... Spiral groove, 8... Datater, 10... Gap part,
16... Space inside the pump body.

Claims (1)

[Scope of utility model registration request] A gap 10 is formed between the outer circumferential surface 6 of the drive mechanism 2 and the rotor 8 to fill the drive mechanism 2 with purge gas and allow the filled purge gas to flow out into the pump body internal space 16.
In the turbo molecular pump formed by the inner circumferential surface 11 of the drive mechanism part 2 which forms the gap part 10
A spiral groove 7 is formed on either the outer circumferential surface 6 of the rotor 8 or the inner circumferential surface 11 of the rotor 8 in order to discharge the purge gas in the drive mechanism section 2 to the pump body internal space 16 side by the rotation of the rotor 8. A turbo molecular pump that is characterized by