JP2001132684A - Turbo-molecular pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a turbo-molecular pump capable of anticipating maintenance time. SOLUTION: A light emitting element 21, a light receiving element 22 and optical fibers 23, 24 are provided, the light from the light emitting element 21 is outputted from an optical fiber end surface 23a inside of a pump via the optical fiber 23 to be reflected by a rotor blade 14 composed of an aluminum alloy to be made incident on an optical fiber end surface 24a to reach the light receiving element 22 via the optical fiber 23. Since the light is attenuated relatedly to the sticking quantity when a product material sticks to the optical fiber end surfaces 23a, 24a, the sticking quantity of the product material can be known by monitoring an attenuation quantity of the light to anticipate the sticking quantity of the product material in the rotor blade 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a turbo molecular pump used for a film forming apparatus or the like.

[0002]

2. Description of the Related Art In a conventional turbo-molecular pump, a rotor blade is arranged in a casing so as to be rotatable at a high speed, and a rotor blade protruding from an outer periphery of the rotor blade and a stator blade fixed to an inner periphery of the casing. The interaction forms a turbine. The turbine converts the gas molecules sucked from the intake port into
Compress and exhaust toward the exhaust port.

When such a turbo molecular pump is used as a vacuum pump of a film forming apparatus using a reactive gas, a product of the reactive gas adheres to the inside of the pump. In particular, if it adheres to the rotor blade (rotor blade), it causes poor rotation of the rotor blade and a decrease in exhaust performance, so that maintenance or the like is required.

[0004]

However, in the past, measures such as maintenance were performed after poor rotation of the rotor blades or poor exhaust performance occurred, so that the operation of the apparatus was suspended due to maintenance at irregular times. This had an adverse effect on production planning.

In the case where maintenance is performed periodically, unnecessary maintenance may be performed as a result at a stage where there is no problem with rotation failure or exhaust performance, resulting in unnecessary maintenance costs. I had to stop driving.

Accordingly, an object of the present invention is to provide a turbo molecular pump capable of predicting a really necessary maintenance time.

[0007]

According to the turbo molecular pump of the present invention, the light emitted from the light emitting element is guided into the space by the means for introducing the light into the space inside the pump, and then passes through this space. The light is guided to the light receiving element by means for leading the light to the light receiving element.

The light introducing means and the light outputting means may use two optical fibers, or connect an optical switch to one optical fiber to switch the connection between the light emitting element and the light receiving element. Configurations may be used.

In particular, when two optical fibers are used and the light is reflected by the rotor blades, the light from the light emitting element is output from the end face of the optical fiber inside the pump via the optical fiber. The light is reflected by the rotor blade made of an aluminum alloy, is incident on the end face of the optical fiber, and reaches the light receiving element via the optical fiber. Then, when the product adheres to the end face of the optical fiber, the light is attenuated in relation to the amount of adherence. Therefore, the amount of adhered product can be known by monitoring the amount of light attenuation.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described.
This will be described with reference to FIGS.

The casing 11 has an intake port 12 at an upper end, and inside thereof, stator blades 13 are fixed in multiple stages in the axial direction.

A rotor blade 14 having a multi-stage rotor blade 14 which is alternately and axially opposed to the stator blade 13 and constitutes a turbine is connected to a shaft 15, and the shaft 15 is provided with a magnetic bearing or the like. It is rotatably supported by a ball bearing (not shown).

The shaft 15 is driven to rotate by a motor (not shown), and the gas sucked in from the inlet 12 is efficiently exhausted to the outlet 16 by the interaction between the rotor blades 14 and the stator blades 13.

On the base 17 of the casing 11, two optical fibers 23 and 24 connected to the light emitting element 21 and the light receiving element 22 outside the casing 11 are mounted on the base 17 in a sealed manner. The light emitted from the light emitting element 21 is disposed so as to be guided out of the optical fiber 23, totally reflected by the rotor blade 14, introduced from the optical fiber 24, and incident on the light receiving element 22.

The products are mainly deposited on the surfaces of the gaps between the rotor blades 14 and the casing 11 and the base 17.
Similarly, the products accumulate on the output end face 23a and the input end face 24a, and the optical fiber end faces 23a, 24
Arranging a is suitable for measuring the product.

Further, a driving section 25 for controlling light emission from the light emitting element 21 and a signal processing section for processing a signal from the light receiving element 26 are connected to the light emitting element 21 and the light receiving element 22, respectively.

Next, in the turbo-molecular pump shown in FIG.
The monitoring of the product will be described with reference to FIGS. The measurement of the adhesion amount of the product can be performed regardless of whether the rotor blades 14 of the turbo molecular pump are rotating or stopped. In particular, when the measurement is performed during rotation, the adhesion amount on the surface of the rotor blades 14 is averaged. Therefore, it is possible to eliminate a measurement error caused by uneven adhesion.

First, when the light emitting element 21 is driven by the driving unit 25, the light emitted from the light emitting element 21 passes through the optical fiber 23 and is emitted from the optical fiber end face 23a.
It is totally reflected by a specific portion of the rotor blade 14 made of an aluminum alloy, enters from an optical fiber end face 24a,
And enters the light receiving element 22, and the sensor signal from the light receiving element 22 is input to the signal processing unit 26. In this embodiment, since the pressure is high inside the turbo molecular pump and the product is most likely to adhere to the turbo molecular pump, and since the surface is flat, the unevenness of light reflection is minimized. The light is reflected at the side end face.

After the light is emitted from the light emitting element 21, the emitted light end face 23 a of the optical fiber 23, the rotor blade 14 face, and the incident light end face of the optical fiber 24 are kept until the light is incident on the light receiving element 22 via the above-described path. Since the light is attenuated in relation to the amount of the product deposited on 24a, the product deposited in the casing 11 can be estimated by quantitatively monitoring the attenuation of the light.

As an additional function of the present embodiment, the configuration of the optical fibers 23, 24, the light receiving element 22, and the signal processing unit 26 allows the infrared radiation from the rotor blade 14 to be monitored. It is possible. In this type of turbo molecular pump, usually, as a measure against the adhesion of products, the pump is often used while heating it to a temperature higher than the solidification temperature of the generator, but the aluminum alloy, which is the material of the rotor blades 14, has a low deterioration temperature. It is beneficial to monitor the temperature as a radiation thermometer because it cannot be heated more than necessary.

Further, the optical fiber 23 and the optical fiber 24 are short-circuited, and a light path of a dummy system for directly receiving the light emitted from the light emitting element 21 by the light receiving element 22 is separately provided. The light output of the light emitting element 21 and the light receiving element 2
2 can reduce measurement errors due to the influence of the time-dependent change, temperature characteristics, and stray light inside the pump.

Further, in this embodiment, the optical fibers 23 and 24 are mounted so as to receive the light totally reflected by the rotor blade 14, but an optical fiber fixing base is provided on the base 17, and the two optical fibers are mounted. The same effect can be obtained even if the end faces are mounted so as to face each other. In this case, since it does not depend on the amount of adhered products on the rotor blades, it is possible to eliminate errors caused by unevenness in the amount of adhered products on the rotor blades even during stoppage.

As shown in FIG. 3, the present invention also includes a configuration in which the number of optical fibers 23 for transmitting and receiving light is reduced to one and an optical switch 30 such as an AO switch is added.
That is, the light emitting element 21 is pulse-driven by the driving unit 25, synchronized with the pulse output, and the optical switch 30 is switched to the light emitting element 22 side, so that the optical fiber 23
An optical pulse is input to b. Further, the optical switch 30 is synchronized with the input timing of the reflected light from the rotor blade 14.
Is switched to the light receiving element 22 side, and the amount of adhered product can be measured even when reflected light is received.

[0024]

As described above, according to the present invention, since the amount of adhered products inside the pump is monitored, it is possible to accurately judge the necessity of maintenance of the turbo molecular pump. It is not necessary to perform any kind of maintenance, so that maintenance costs can be reduced and the operation rate of the apparatus can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a turbo-molecular pump of the present invention.

FIG. 2 is a partially enlarged view of an optical fiber in the base of the turbo-molecular pump of the present invention.

FIG. 3 is a schematic configuration diagram of a modified embodiment of the present invention.

[Explanation of symbols]

 14 rotor blade 21 light emitting element 22 light receiving element 23, 24 optical fiber 23a, 24a optical fiber end face

Claims (1)

[Claims] 1. A turbo-molecular pump comprising: means for introducing light from a light-emitting element into a space inside a turbo-molecular pump; and means for guiding light passing through the space inside the pump to a light-receiving element. .