JP5397138B2 - Turbo molecular pump - Google Patents

Description

  The present invention relates to a turbo molecular pump.

  The turbo molecular pump exhausts gas by rotating a rotor on which a rotor blade is formed with respect to a fixed blade at a high speed. The fixed blades are provided in a plurality of stages so as to be alternately arranged in the axial direction with respect to the rotating blades. The fixed wings of each stage are sandwiched between ring-shaped spacer rings and positioned in the axial direction and the radial direction (see, for example, Patent Document 1).

JP 2008-144694 A

  By the way, each fixed blade is disposed so as to be inserted between the upper and lower rotor blade stages, and thus is divided into a semicircular shape so that it can be assembled from the side of the rotor blade. The divided semicircular fixed blades are positioned by sandwiching the outer peripheral portion with a spacer ring. For this reason, the fixed wing may be displaced when the spacer ring is assembled, and workability is poor.

The invention according to claim 1 is a turbo molecular pump comprising: a rotating body having a plurality of stages of rotating blades formed in the axial direction; and a plurality of stages of fixed blades alternately arranged in the axial direction with respect to the plurality of stages of rotating blades. At least one stage of the plurality of stages of fixed wings is composed of a plurality of divided fixed wings arranged so as to be in contact with the circumferential direction, and the divided fixed wings include a plurality of wing blades arranged in parallel in the circumferential direction; and the outer peripheral portion of the plurality of blades blade is coupled, and a circular arc-shaped spacer portion for positioning the wing blade plurality of the predetermined positions, each spacer of the plurality of divided stator blade coupled is an arcuate The end surfaces of the spacer portion formed are in contact with each other, and the contacted end surfaces form a labyrinth structure in the radial direction .
According to a second aspect of the present invention, there is provided the turbomolecular pump according to the first aspect, wherein a coupling member for coupling a plurality of divided fixed blades to each other is provided.
According to a third aspect of the present invention, in the turbomolecular pump according to the second aspect, the coupling member is an elastic ring attached to the outer periphery of the spacer portions of the plurality of divided fixed blades arranged in the circumferential direction. .
According to a fourth aspect of the present invention, in the turbo molecular pump according to any one of the first to third aspects , in addition to the radial labyrinth structure , the abutting end surfaces form an axial labyrinth structure. Features.
A fifth aspect of the present invention is the turbomolecular pump according to any one of the first to fourth aspects, wherein the split fixed blades are integrally formed by casting.
A sixth aspect of the present invention is the turbomolecular pump according to any one of the first to fifth aspects, wherein a plurality of stages are provided so that the fixed blades composed of a plurality of divided fixed blades are stacked, and the spacer portion The circumferential position of the portion where the end faces of the two abuts is different between the adjacent fixed blades.
A seventh aspect of the invention is the turbomolecular pump according to any one of the first to sixth aspects, further comprising a Ziegburn pump stage having a radial thread groove, the Ziegburn pump stage being arranged in the circumferential direction. A plurality of divided portions arranged so as to be in contact with each other are connected to each other by an elastic ring, and the plurality of divided portions are formed on a pump portion in which a thread groove is formed and on an outer periphery of the pump portion, and And an arcuate spacer portion for positioning the pump portion at a predetermined position.

  According to the present invention, it is possible to improve the efficiency of assembly work.

It is sectional drawing which shows schematic structure of the turbo-molecular pump 1 by this invention. It is a figure explaining the fixed wing | blade 33 in this Embodiment, (a) is a top view, (b) is a side view. 3 is a cross-sectional view showing a laminated structure of fixed wings 33. FIG. It is a figure which shows the modification of a parting line, (a) shows a 1st modification, (b) shows a 2nd modification. It is a figure explaining the Ziegburn pump stage 50 in this Embodiment, (a) is a top view, (b) is a half sectional view.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. FIG. 1 is a sectional view showing a schematic configuration of a turbo molecular pump 1 according to the present invention. The turbo molecular pump 1 shown in FIG. 1 is a magnetic bearing type pump, and the rotor 30 is supported in a non-contact manner by electromagnets 37 and 38 constituting a 5-axis magnetic bearing. The rotor 30 magnetically levitated by the magnetic bearings is driven to rotate at high speed by the motor 36.

  The rotor 30 is formed with a plurality of stages of rotating blades 32 and a cylindrical screw rotor 31. On the other hand, on the fixed side, a plurality of fixed blades 33 arranged alternately with the rotary blades 32 in the axial direction, and a screw stator 39 provided on the outer peripheral side of the screw rotor 31 are provided. A thick spacer portion 332 that functions as a spacer is formed on the outer peripheral portion of each fixed wing 33. By laminating the fixed blades 33 on the base 20 so that the spacer portions 332 overlap, the fixed blades 33 are positioned at predetermined positions between the rotary blades 32. When the pump casing 34 formed with the inlet flange 21 is fixed to the base 20, the stacked rotor blades 33 are sandwiched between the base 20 and the pump casing 34.

  The base 20 is provided with an exhaust port 22, and a back pump is connected to the exhaust port 22. When the rotor 30 is magnetically levitated and driven at high speed by the motor 36, the gas on the intake port 21a side is exhausted to the exhaust port 22 side.

  2A and 2B are diagrams illustrating the fixed wing 33 in the present embodiment, where FIG. 2A is a plan view and FIG. 2B is a side view. FIG. 2 shows one stage of the fixed wing 33 at the lower stage where the wing height is relatively low. As described above, since the fixed wing 33 is inserted between the rotor blades 32 from the side of the rotor 30 during assembly, the circular rotor blade 33 needs to be divided into at least two. In the example shown in FIG. 2, the rotary blade 33 is constituted by a pair of semicircular divided fixed blades 33a and 33b. Reference numeral L1 represents a dividing line.

  Each of the divided fixed blades 33a and 33b includes a semi-ring-shaped inner rib portion 331 and a spacer portion 332, and a plurality of blade blades 330 formed therebetween. As shown in the side view of FIG. 2 (b), the two split fixed wings 33 a and 33 b are integrated by a coupling member constituted by an elastic ring 40. In the present embodiment, an O-ring is used as the elastic ring 40. The O-ring 40 has a function of sealing the gap with the pump casing 34 as shown in FIG. 1 as well as a function of combining and integrating the split fixed blades 33a and 33b. With this sealing function, the downstream side and the upstream side of the O-ring 40 are separated in the gap between the fixed blade 33 and the pump casing 34, and gas backflow to the upstream side can be prevented.

  FIG. 3 is a cross-sectional view corresponding to the AA cross section of FIG. 2A, and the two-stage fixed blades 33 are shown so that the laminated structure can be easily understood. The spacer portion 332 functions as a spacer when the fixed blades 33 are stacked, and unevenness is formed on the upper surface and the lower surface thereof. When the fixed wings 33 are stacked, the convex portion 335 formed on the upper surface of the spacer portion of one fixed wing 33 fits into the concave portion 336 formed on the lower surface of the other fixed wing 33. By adopting such a fitting structure, the fixed wings 33 are prevented from shifting in the radial direction (the horizontal direction in the figure). A groove 334 for mounting the O-ring 40 is formed on the outer peripheral surface of the spacer portion 332. For example, when assembling the upper fixed wing 33 on the lower fixed wing 33 in FIG. 3, first, a pair of split fixed wings 33a and 33b are placed on the lower fixed wing 33 from the lateral direction. Then, the surface of the dividing line L1 is closely matched. Thereafter, the O-ring 40 is mounted in the groove 334 of the split fixed blades 33a and 33b, and the split fixed blades 33a and 33b are coupled.

  In the present embodiment, the split fixed wings 33a and 33b are manufactured by die casting or the like, but they may not be cast. In the conventional turbo molecular pump, the fixed wing and the spacer ring are formed separately, and the circular fixed wing is generally cut in two. For this reason, the gap at the parting line portion is approximately the same as the width of the tool at the time of cutting the fixed blade, and there is a problem that the divided fixed blade is likely to be displaced during assembly. In addition, since it is necessary to stack the spacer rings so that the divided fixed blades do not shift, it takes time and effort during assembly.

  On the other hand, in the case of the above-described split fixed blades 33a and 33b, the conventional rotor blade portion and the portion corresponding to the spacer ring (spacer portion 332) are integrally formed, thereby reducing the processing cost and the number of parts. Can be reduced, and workability at the time of assembly can be improved. Further, since the O-ring 40 is integrally fixed, there is no fear that the divided fixed blades 33a and 33b are displaced during assembly. Moreover, the gas backflow of the parting line L1 can also be reduced. In addition, the reverse flow in this spacer part 332 becomes remarkable as the area | region close | similar to a viscous flow downstream.

  In addition, since it can be molded with high precision when integrally molded by die casting, the gap of the parting line L1 can be reduced to the assembly accuracy level, and when the parting line is integrated with the O-ring 40 that is an elastic body. It becomes possible to match both in the L1 portion. As a result, the backflow of gas in the parting line L1 can be substantially prevented.

  If the positions of the dividing lines L1 are aligned when the fixed wings 33 are stacked one above the other, the backflow path is formed in a plurality of stages, so that the influence of the backflow appears further upstream. Therefore, when the fixed wing 33 is assembled, the influence of the backflow can be reduced by shifting the position of the dividing line L1 as shown in FIG. For example, when the fixed wing 33 is divided into two, they are shifted by 90 degrees from each other. As such, a positioning pin may be provided between the upper and lower spacer portions in order to shift the arrangement.

  FIG. 4 is a diagram showing a modification of the dividing line. FIG. 4A is a view showing a first modification of the dividing line, and shows a part of the divided fixed blades 33a and 33b including the dividing line L2. The dividing line L2 is bent in a zigzag shape in the radial direction in the spacer portion 332. That is, the part of the dividing line L2 forms a labyrinth structure in the radial direction. By adopting such a labyrinth structure, it is possible to more reliably separate the exhaust region where the rotary blade 32 and the fixed blade 33 are provided, and the gap space between the spacer portion 332 and the pump casing 34.

  On the other hand, the side view of the fixed wing 33 (33a, 33b) shown in FIG. 4 (b) shows a second modification regarding the dividing line. In addition, illustration of the O-ring 40 was abbreviate | omitted in FIG.4 (b). In the case of the dividing line L3, it is bent zigzag in the axial direction. That is, the dividing line L3 extending in the axial direction is bent in the circumferential direction in the middle, and then bent again in the axial direction, and the part of the dividing line L3 forms a labyrinth structure. By setting it as the shape like the dividing line L3, the backflow of the gas of the up-down direction in the spacer part 332 can be suppressed.

  Some turbomolecular pumps have a Ziegburn pump stage in the downstream pump stage. FIG. 5 shows a case where the spacer ring is integrated and divided in the Ziegburn pump stage like the above-described fixed blade 33. The Ziegburn pump stage 50 has a disc shape, and a spiral convex portion 500 and a concave portion 501 extending in the radial direction are formed on at least one surface of the disc. The uneven portions 500 and 501 constitute screw grooves. On the rotor side, a flat disk or a disk formed with a screw groove is provided so as to face the concavo-convex parts 500 and 501.

  In the present embodiment, the Ziegburn pump stage 50 includes two divided portions 50a and 50b, and arc-shaped spacer portions 502 having a positioning function similar to the spacer ring are provided on the outer peripheral sides of the uneven portions 500 and 501, respectively. Is formed. A groove 504 in which the O-ring 40 is mounted is formed on the side surface of the spacer portion 502. A convex portion 505 is formed on the upper surface of the spacer portion 502, and a concave portion 506 is formed on the lower surface. These uneven portions 505 and 506 have the same functions as the uneven portions 335 and 336 of FIG. 3 described above. In the case of the Ziegburn pump stage 50 as well, the dividing portions 50a and 50b are integrated by the O-ring 40, thereby improving the adhesion of the dividing line L1 portion and suppressing the back flow in the dividing line portion L1 as much as possible. .

  In the above-described embodiment, the O-ring 40 that is an elastic ring is used as a coupling member for integrating the split fixed wings 33a and 33b and the split portions 50a and 50b. A circular shape may be used. Another example of the coupling member is a wire such as a wire.

  In the above-described embodiment, the magnetic bearing type turbo molecular pump has been described as an example. However, the present invention is not limited to the magnetic bearing type and can be applied to other turbo molecular pumps. Further, in the example shown in FIG. 1, the structure shown in FIG. 2 is adopted for the fixed blades 33 at all stages, but the structure of FIG. 2 is adopted only for a part (for example, the downstream fixed blade stage). However, a conventional structure may be adopted in other stages. Furthermore, the number of divisions of the fixed blade 33 and the Ziegburn pump stage 50 may not be two.

  Each of the embodiments described above may be used alone or in combination. This is because the effects of the respective embodiments can be achieved independently or synergistically. In addition, the present invention is not limited to the above embodiment as long as the characteristics of the present invention are not impaired.

  1: turbo molecular pump, 30: rotor, 32: rotor blade, 33: fixed blade, 33a, 33b: split fixed blade, 40: O-ring, 50: Ziegburn pump stage, 50a, 50b: split section, 330: blade Blade, 331: inner rib part, 332, 502: spacer part, 334, 504: groove, 335, 500, 505: convex part, 336, 501, 506: concave part, L1 to L3: dividing line

Claims (7)

In a turbo molecular pump comprising: a rotating body in which a plurality of stages of rotating blades are formed in the axial direction; and a plurality of stages of fixed blades alternately arranged in the axial direction with respect to the plurality of stages of rotating blades.
At least one stage of the plurality of stages of fixed wings is composed of a plurality of divided fixed wings arranged so as to contact the circumferential direction,
The split fixed blade includes a plurality of blade blades arranged in parallel in the circumferential direction, and an arcuate spacer portion that connects the outer peripheral portions of the blade blades to position the blade blades at predetermined positions. Prepared ,
The turbo molecular pump characterized in that the spacer portions of the combined plurality of divided fixed blades are in contact with each other at the end surfaces of the arcuate spacer portions, and the contacted end surfaces form a radial labyrinth structure. . The turbo-molecular pump according to claim 1,
A turbo-molecular pump characterized in that a coupling member for coupling the plurality of divided fixed blades is provided. The turbo-molecular pump according to claim 2,
The turbo molecular pump according to claim 1, wherein the coupling member is an elastic ring attached to an outer periphery of the spacer portion of the plurality of divided fixed blades arranged in the circumferential direction. In the turbomolecular pump according to any one of claims 1 to 3 ,
The abutting end faces also form a labyrinth structure in the axial direction in addition to the labyrinth structure in the radial direction. In the turbo molecular pump according to any one of claims 1 to 4,
The turbo-molecular pump, wherein the divided fixed blades are integrally formed by casting. In the turbomolecular pump according to any one of claims 1 to 5,
The fixed wing composed of the plurality of divided fixed wings is provided in a plurality of stages so as to be laminated,
A turbo molecular pump characterized in that the circumferential position of the portion where the end faces of the spacer portion abut on each other is different between the adjacent fixed blades. In the turbomolecular pump according to any one of claims 1 to 6,
Having a Ziegburn pump stage with radial thread grooves,
In the Ziegburn pump stage, a plurality of divided portions arranged so as to be in contact with each other in the circumferential direction are coupled to each other by an elastic ring,
The plurality of divided portions include a pump portion in which a thread groove is formed, and an arc-shaped spacer portion that is formed on an outer periphery of the pump portion and positions the pump portion at a predetermined position. Molecular pump.

Images