JP3879169B2 - Turbo molecular pump - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a turbo molecular pump, and more particularly to mounting a turbo molecular pump to a vacuum vessel.
[0002]
[Prior art]
In a turbo molecular pump, a drive shaft provided with an exhaust blade is housed in a casing, and this casing is formed on a support body such as a vacuum vessel on flange portions 101 provided on the casing and the vacuum vessel, respectively. The circular through-hole 102 (see FIG. 5) is attached using a plurality of bolts. If there is a material defect in the wing material, or if the wing material is subjected to stress corrosion due to the use of corrosive gas, the wing body will break during rotation and the fixed wing body fixed to the casing Rotational energy of the damaged exhaust blade may fall on the casing and the vacuum vessel.
[0003]
[Problems to be solved by the invention]
Therefore, the rotational energy of such damaged parts can transmit the rotational force from the casing to the vacuum vessel, and the vacuum vessel may be damaged. Therefore, the thickness of the vacuum vessel is increased or a high-strength material is used. However, all of these resulted in increased costs and increased equipment weight.
[0004]
Therefore, the present invention solves the problems of conventional turbomolecular pumps, and is a turbomolecular pump that can securely fix a casing to a support such as a vacuum vessel without causing an increase in cost and weight of the apparatus. For the purpose of provision.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, a turbo molecular pump according to claim 1 of the present invention has a casing attached to a support via an attachment jig, and an exhaust wing and a motor are provided in the casing. In a turbo molecular pump having a drive shaft that rotates and to which the exhaust wing body is attached, the mounting jig is a long hole-shaped bolt hole that is curved along the rotation direction of the drive shaft and coincides with the rotation direction. And the casing rotates the rotational energy by rotating relative to the support body against a bolt tightening force when the exhaust blade is damaged and the rotational energy is transmitted to the casing. It is attached to the said support body by fixing with a volt | bolt so that it may consume. The turbo molecular pump described in claim 2 is a drive in which a casing is attached to a support via an attachment jig, and the exhaust wing is attached to the casing by being rotated by an exhaust wing and a motor. In the turbo-molecular pump having a shaft, the mounting jig includes a bolt hole having an inner diameter into which a buffer member mounted around a bolt for mounting the support and the casing can be inserted, and the shape of the bolt hole is the drive The elongated hole shape is curved along the rotational direction of the shaft and coincides with the rotational direction, and the casing is attached to the support by attaching the buffer member around the bolt and fixing it to the bolt hole. The buffer member is configured to reduce the rotational energy transmitted to the casing when the exhaust wing body is damaged due to its own damage. Characterized in that it drain in.
[0006]
In the turbo molecular pump according to claim 1, the broken parts transmitted to the casing are allowed to rotate relative to the support body in a limited range against the tightening force of the bolts. Consume energy. Further, in the turbo molecular pump described in claim 2, the energy of the damaged part transmitted to the casing is consumed by the breaking energy of the buffer member attached around the bolt. Further, the turbo molecular pump described in claim 3 consumes the energy of the damaged parts transmitted to the casing by combining the shock absorbing mechanism of the turbo molecular pump described in claims 1 and 2.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a schematic sectional view of a turbo molecular pump according to the present invention. In FIG. 1, a turbo molecular pump includes a fixed wing body 3 that is attached to the inside of a casing 50 via a spacer 4, and an exhaust wing body that is attached to the drive shaft 1 and is opposed to the fixed wing body 3. 2, and a turbine blade is formed, and the exhaust blade 2 is rotated at a high speed by the high-frequency motor 33 with respect to the fixed blade 3, thereby transferring gas molecules sucked from the intake 5 to the exhaust 6. .
[0008]
Further, a vacuum vessel 51 for supplying a fluid sucked by a pump is provided on the intake port 5 side. As shown in FIG. 2, a flange 50a on the casing 50 side and a flange 51a on the vacuum vessel 51 side are connected to a bolt. The casing 50 is fixed to the vacuum vessel 51 by being tightened with a jig such as 52 and a nut.
[0009]
Furthermore, as shown in FIG. 1, the magnetic bearing device that supports the drive shaft 1 provided with the exhaust blade 2 in a non-contact manner includes radial magnetic bearings 34a and 34b provided with electromagnets in the radial direction of the drive shaft 1, And a thrust bearing 34c provided with an electromagnet in the axial direction. A radial sensor 31a for detecting the state of the drive shaft 1 and a displacement sensor 31b such as a thrust sensor are installed at substantially the same position as the electromagnet to constitute a feedback control system. The drive shaft 1 is supported at the center position by adjusting the current flowing through each electromagnet to adjust the attractive force of the electromagnet.
[0010]
The electromagnets are arranged opposite to each other with the drive shaft 1 interposed therebetween, and an excitation current determined by PID control or the like is supplied to each electromagnet via an excitation amplifier, and the position of the drive shaft 1 is controlled by the attractive force of the opposing electromagnet. And magnetic levitation control. Further, the rotational speed of the exhaust blade 2 is obtained by detecting the rotational speed of the drive shaft 1 by the rotation sensor 32.
[0011]
In such a turbo molecular pump, when the exhaust wing body 2 is damaged due to material defects or corrosion, the drive shaft 1 provided with the exhaust wing body 2 loses balance, and the main body of the drive shaft 1 is the protective bearing 7. , 8, but the broken pieces of the exhaust wings that fall are dropped on the fixed wing 3 and the like, and the rotational energy is transmitted to the entire casing 50, so that the casing 50 tries to rotate.
[0012]
By the way, about the casing 50, the vacuum vessel 51 which supplies the fluid suck | inhaled with a turbo-molecular pump is provided in the long hole 53 provided in each flange 50a, 51a of the casing 50 and the vacuum vessel 51 as shown in FIG. A bolt 52 is penetrated and attached. The plurality of bolts 52 are all fixed to the plurality of elongated holes at the ends in the rotational direction of the exhaust blade body 2. Therefore, as described above, when the exhaust wing body 2 is damaged and its rotational energy is transmitted to the casing 50, the casing 50 is relatively relative to the vacuum vessel 51 by the length S against the tightening force of the bolts. Since it rotates, the rotational energy of the damaged exhaust blade is consumed as energy required for the rotation, the stress applied to the vacuum vessel 51 is weakened, and these are not damaged.
[0013]
In other words, the turbo molecular pump can be securely attached to the casing 50 with a simple configuration in which the through holes of the bolts 52 in the flanges 50a and 51a are the long holes 53 without increasing the cost and the weight of the apparatus as described above. can do.
[0014]
As shown in FIG. 4, a shock absorbing member 54 that has low rigidity and is damaged or elastically deformed is attached around the bolt 52, and is inserted into the through holes 53 of the flanges 50a and 51a together with the bolt 52. It is also possible to prevent damage to the vacuum vessel 51 by consuming the energy when the casing 50 is rotated by the rotational energy of the wing body for use with the breaking energy or elastic energy of the buffer member. Further, by combining with the structure in which the through hole of the flange as described above is the long hole 53, it is possible to further effectively prevent the vacuum vessel from being damaged.
[0015]
【The invention's effect】
As described above, according to the present invention, the casing can be rotated within a limited range with respect to a support such as a vacuum vessel, so that the rotation consumes the rotational energy of the damaged part, and the vacuum Since the damage energy applied to the container is weakened, there is no need to increase the thickness of the vacuum container or to use a high-strength material, and the pump is securely attached to a support such as a vacuum container without increasing the cost and weight of the device. be able to.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a turbo molecular pump according to the present invention.
FIG. 2 is a mounting diagram of the turbo molecular pump of the present invention with respect to a vacuum vessel.
FIG. 3 is a schematic plan view of a flange viewed from below in the turbo molecular pump of the present invention.
FIG. 4 is a schematic cross-sectional view of a flange in the turbo molecular pump of the present invention.
FIG. 5 is a schematic plan view of a flange as viewed from below in a conventional turbomolecular pump.
[Explanation of symbols]
1 Drive shaft 50 Casing 50a Flange 51 Vacuum vessel 51a Flange 52 Bolt 53 Long hole

Claims (2)

In a turbo molecular pump having a drive shaft on which a casing is attached to a support via an attachment jig, rotated by an exhaust wing body and a motor, and the exhaust wing body is attached to the casing, the attachment jig includes: A bolt hole having a long hole shape that is curved along the rotation direction of the drive shaft and coincides with the rotation direction, and the casing is bolted when the exhaust blade is damaged and the rotational energy is transmitted to the casing. A turbo molecular pump, wherein the turbo molecular pump is attached to the support by being bolted so as to consume the rotational energy by rotating relative to the support against the tightening force. In a turbo molecular pump having a drive shaft on which a casing is attached to a support via an attachment jig, rotated by an exhaust wing body and a motor, and the exhaust wing body is attached to the casing, the attachment jig includes: A bolt hole having an inner diameter into which a cushioning member attached around the bolt for attaching the support and the casing can be inserted is provided, and the shape of the bolt hole is along the rotation direction of the drive shaft and coincides with the rotation direction. The casing has a curved long hole shape, and the casing is attached to the support body by attaching the buffer member around the bolt and fixing it to the bolt hole, and the buffer member is attached to the exhaust wing body by breakage. A turbo-molecular pump that consumes rotational energy transmitted to the casing by its own damage.

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