JPH10205486A - Vacuum pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent accumulation of condensed liquid and a solidified solid in a pump and to prevent overheating of a constitution member on which an adverse influence is exercised by a high temperature. SOLUTION: The whole of a vacuum pump is divided into three mechanism parts of a mechanism part 1 on the high vacuum side; a mechanism part 2 on the back pressure side; and a drive/bearing mechanism part 3. The three mechanism parts are heat-insulated from each other. The heat insulation is achieved in a way that the area of a contact surface between the adjoining mechanism part is decreased by excess lump removing parts 15, 16, and 17 in a radial direction and an axial direction formed by turning. Further, a contact surface incapable of being structurally eliminated is formed of a heat insulation material. Since a heating element, a cooling device, and a temperature sensor are arranged, a desired temperature condition is satisfied throughout the whole area of the internal parts of the mechanism on the high vacuum side and the mechanism on the back pressure side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum pump, and examples of the vacuum pump include a turbo molecular pump, a molecular pump, and a combination thereof. More specifically, the present invention includes a high vacuum side mechanism and a back pressure side mechanism having a rotating side member and a fixed side member that cooperate with each other to generate a pump action, and further includes a drive / bearing mechanism. It relates to a vacuum pump. In the following description, the vacuum pump is sometimes called a friction pump.

[0002]

2. Description of the Related Art Vacuum pumps of this type are often configured as multi-stage pumps having a plurality of pump stages, and different types of pump stages may be combined. Each pump stage is composed of a rotor member and a corresponding stator member. The rotor member and the stator member that generate the pumping action are arranged in an axial direction, which is the flow direction of the gas transported by the pumping action. In order to achieve the optimum pump performance that can maximize the gas flow rate and the compression ratio, the rotating member must be rotated at high speed. Of the drive energy required for this high-speed rotation, only a small part is converted into kinetic energy of gas. Most of the driving energy will be dissipated as lost heat. In addition, there is other undesired heat generation, such heat is also generated from bearings (in the case of ball bearings, it is generated as mechanical loss heat due to friction, and in the case of magnetic bearings, it is generated as electric loss heat). Occurs), and also occurs when the gas is compressed. These heat sources cause undesired temperature rises in the drive / bearing mechanism and the mechanism provided with the components generating the pumping action, and such a temperature rise adversely affects these mechanisms. There is. In extreme cases, the rotation of the rotor may stop and even the pump may be damaged. for that reason,
In order to prevent components that require high precision from being overheated, this type of pump is provided with a cooling device.

[0003]

SUMMARY OF THE INVENTION Friction pumps of the type described above are becoming more and more used, for example, in the process of chemical processing and in the production of semiconductors. A large amount of gas that easily condenses may flow into the pump. Further, in such applications, the vacuum vessel may have to be evacuated to an ultra-high vacuum. In such a case, the gas transported by the pump mechanism may be compressed in the pump mechanism to a pressure at which laminar flow becomes dominant. In this case, a relatively high pressure gas is transported in a relatively large amount in the pump mechanism. If the gas is a condensable gas, and particularly if the temperature of the gas is low, a significant portion of the gas will condense to a liquid or solidify to a solid. This causes erosion and corrosion, which can damage individual components and even the entire pump. The accumulation of solidified solids, particularly in the molecular pumping mechanism, narrows the gap that was originally very narrow, which can lead to reduced output and, in the worst case, even to pump failure. .

As mentioned earlier, vacuum pumps of the type described here need to be equipped with a cooling device in order to prevent components requiring high precision from overheating. However, on the other hand, by the action of the cooling device,
The accumulation of condensed liquids and solidified solids can be promoted, which can also cause problems associated with the operation of such pumps, as described above.

Therefore, a vacuum pump of the type described above is used for applications such as chemical processes and semiconductor manufacturing, and if the vacuum pump does not function over a wide pressure range in such applications. If not, the construction of the vacuum pump would have to fulfill two essentially conflicting, if not completely impossible, conditions.

[0006] European Patent Publication EP-O-35268.
In No. 8, a member having a large thermal resistance is provided as an additional member between the high-temperature component and the low-temperature component in order to prevent heat transfer from the high-temperature component to the low-temperature component. The structure is shown. However, such a structure has the disadvantage that the external dimensions are large. In addition, it is necessary to add a packing and a connecting member. All of these additional members are components that require high accuracy, and the additional members complicate the overall structure. Furthermore, the above disadvantages are compounded when the multiple mechanical parts of the pump are to be thermally separated from one another.

Accordingly, it is an object of the present invention to provide a vacuum pump of the friction pump type operable over a wide pressure range, which can highly prevent the accumulation of condensed liquids or solidified solids and which is adversely affected by high temperatures. It is an object of the present invention to provide a vacuum pump capable of preventing overheating of components receiving the vacuum pump. Also,
In order to make these possible, it is also important that the external dimensions of the vacuum pump do not increase and that no extra components requiring high precision are required.

[0008]

The above object is achieved by the features described in the characterizing part of claim 1. Claims 2 to 10 describe specific configurations according to the embodiments of the present invention.

According to the structure of the vacuum pump having the constituent features described in the characterizing part of claim 1, and according to the structure of the vacuum pump described in each dependent claim dependent on claim 1, Two mutually contradictory conditions, which are basic conditions for the structure of a kind of pump, are both satisfied. The high vacuum side mechanism, the back pressure side mechanism, and the drive / bearing mechanism, which are the three mechanism parts of the vacuum pump, are separated from each other by a relief part in the radial and axial directions formed by turning, that is, a lightening part. By reducing the area of the contact surfaces between them, they are thermally separated from each other. Further, the contact surface which cannot be omitted structurally is made of a heat insulating material. For the high vacuum side mechanism, a temperature control operation can be applied independently from the back pressure side mechanism and also from the drive / bearing mechanism, that is, required for individual applications,
Alternatively, control of cooling and heating required at each stage of the application process can be performed. The same applies to the back pressure side mechanism. For example, a situation in which condensed liquid or solidified solid accumulates actively due to an increase in pressure can be prevented by intentionally increasing the temperature. Further, since heat generated during operation of the drive / bearing mechanism is removed by cooling, unregulated or inconvenient heat conduction from the drive / bearing mechanism to other mechanisms is prevented.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail with reference to the drawings according to an embodiment.
The illustrated vacuum pump has a structure in which three mechanism parts are connected, and these three mechanism parts are a high vacuum side mechanism part 1, a back pressure side mechanism part 2, and a drive / bearing mechanism part 3. The high vacuum side mechanism 1 is, in the illustrated embodiment,
It is configured as a turbo molecular pump, and has a plurality of rotor-side impellers 9 and a plurality of stator-side impellers 10,
An intake port 13 is provided. In the illustrated embodiment, the back pressure side mechanism 2 is configured as a Holbek pump type molecular pump. This molecular pump includes a rotating cylindrical member 11 and a stator-side member 12 having a spiral groove. Reference numeral 14 denotes an exhaust port. The drive / bearing mechanism 3 is substantially integrated into a drive motor 4, which drives a shaft 8. The shaft 8 has a high vacuum side mechanism 1 and a back pressure side mechanism 2
Each rotation side component member is attached, and
A bearing mechanism for supporting the shaft 8 is also mounted. In the illustrated embodiment, this bearing mechanism comprises an axial magnetic bearing 5 and a radial equipment bearing 6. Further, a passive type radial magnetic bearing 7 is provided in the high vacuum side mechanism 1. However, some or all of these magnetic bearings may be replaced with other types of bearings, such as ball bearings, for example, and such modifications do not change the essence of the present invention.

Between the high vacuum side mechanism section 1 and the back pressure side mechanism section 2, radial and axial relief sections formed by turning, ie, lightening, are provided for the purpose of insulating the mechanisms from each other. A part 15 is provided. Similarly, between the back pressure side mechanism unit 2 and the drive / bearing mechanism unit 3, a relief part in the radial direction and the axial center direction formed by turning, that is, a lightening part 1 is also provided.
6 is provided. In order to insulate the high vacuum side mechanism 1 from the drive / bearing mechanism 3, in the illustrated embodiment,
A notch, that is, a lightened portion 17 is formed on the shaft 8 by turning. Further, in a portion where a hollow portion cannot be formed structurally or a portion where a contact surface cannot be eliminated structurally, the contact surface is formed of a material having a low thermal conductivity, that is, a thermally defective conductor material. What should I do?
For this purpose, for example, the high vacuum side mechanism 1 and the back pressure side mechanism 2
A mounting member made of such a material is interposed in a portion indicated by reference numeral 18 between the back pressure side mechanism 2
A similar mounting member is also interposed at a portion indicated by reference numeral 19 between the motor and the drive / bearing mechanism 3. High vacuum side mechanism 1
The drive / bearing mechanism 3 can be thermally separated from each other, for example, by interposing a mounting member made of a heat-defective conductor material at a portion indicated by reference numeral 20 of the shaft 8.

A cooling device 21 and a heating device 23 are provided to control the temperature of the high vacuum side mechanism 1, that is, to control the temperature. Further, the temperature sensor 25 is used to monitor the temperature of the high vacuum side mechanism 1 to control the heating operation or the cooling operation. Further, in order to heat the back pressure side mechanism 2, a plurality of rod-shaped heating elements 24 are provided, and the heating elements 24 radially project from the outside of the housing to the inside through the housing.
Further, the heating element 24 can be controlled by monitoring the temperature of the back pressure side mechanism 2 using the temperature sensor 26. The drive / bearing mechanism 3 is provided with a cooling device 22 for removing heat generated therein.

[0013]

As is apparent from the above description, according to the present invention, the gas handled by the vacuum pump is condensed to become a liquid, or solidified to be solidified and deposited in the vacuum pump. This has the advantage that it is possible to prevent it effectively and to prevent overheating of the components of the vacuum pump that are adversely affected by high temperatures.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a vacuum pump according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 High vacuum side mechanism part 2 Back pressure side mechanism part 3 Drive / bearing mechanism part 15, 16, 17 Lightening part 18, 19, 20 Mounting member (heat insulation member)

Continued on the front page (72) Inventor Matthias Mettler Federal Republic of Germany Day-35759 Dried Luf, Herborner Straße 19 (72) Inventor Heinz Reichhard Federal Republic of Germany Day-35614 Asler, Schurstraße 19 (72) Inventor Jörg Stanzell Germany Day-35583 Wetzlar, Bergstrasse 4

Claims (10)

[Claims] A high vacuum side mechanism (1) having a rotating side member and a fixed side member that generate a pump action in cooperation with each other.
And a back pressure side mechanism (2), and further comprising a drive / bearing mechanism (3), wherein the three mechanisms can be individually subjected to a temperature control operation with respect to the mechanisms. A vacuum pump, wherein at least two of the three mechanisms are insulated from each other by appropriate means. 2. The lightening portions (15, 16, 1 and 2) formed between the components of the mechanism portions to reduce the area of the contact surface between the components of the mechanism portions.
The vacuum pump according to claim 1, wherein the vacuum pumps are insulated from each other by (7). 3. The mechanism parts are insulated from each other by members (18, 19, 20) formed of a poorly-heated conductive material constituting all or a part of a contact surface that cannot be omitted structurally. The vacuum pump according to claim 1 or 2, wherein: 4. The vacuum pump according to claim 1, wherein a cooling device (21) is provided in the high vacuum side mechanism (1). 5. The vacuum pump according to claim 1, wherein the high vacuum side mechanism (1) is provided with a heating device (23). 6. The vacuum pump according to claim 1, wherein the drive / bearing mechanism (3) is provided with a cooling device (22). 7. A heating device (2) is provided in the back pressure side mechanism (2).
The vacuum pump according to any one of claims 1 to 6, further comprising (4). 8. The heating device (24) is constituted by a rod-shaped heating element projecting radially or axially into the housing of the back pressure side mechanism (2). Item 7. A vacuum pump according to Item 7. 9. A temperature sensor (25) for monitoring the temperature of the high vacuum side mechanism and controlling the heating device (23) to the cooling device (21) by the high vacuum side mechanism (1). 6. The method according to claim 5, further comprising:
The described vacuum pump. 10. A temperature sensor (26) for monitoring the temperature of the back pressure side mechanism and controlling the heating device (24) is provided in the back pressure side mechanism (2). The vacuum pump according to claim 7 or 8, wherein