JP2010096007A - Rotor of molecular pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the loosening of the engagement of a rotor and a rotating shaft caused by the deformation of the rotor by centrifugal forces acting a large number of rotating blades which are protrusively arranged at the external periphery of the rotor, in the rotor of a turbo-molecular pump which has the rotating shaft at its center and rotates at high speed. <P>SOLUTION: The rotor 1 of the molecular pump has rotor blade stages comprising the plurality of rotor blades 1 and installed in a radially protruding manner and in multiple stages at the external periphery of a cylindrical hollow hub 1a. The rotor 1 is formed in a cup shape with a boss 1c provided at an end of the hub part 1a and axially protruding. An end of the rotating shaft 2 is fitted in a shaft hole 1d formed at the boss 1c, and the rotor is fastened to the rotating shaft 2 with a nut 3 screwed to a screw 2a at the end of the rotating shaft. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a rotor of a molecular pump such as a turbo molecular pump or a composite molecular pump used for generating a vacuum in a pressure range from a medium vacuum to a high vacuum.

  A rotor of a general turbo molecular pump or a composite molecular pump has a rotating shaft at the center and is erected in a casing and rotates at a high speed of several tens of thousands of times per minute.

  As an example of such a molecular pump, a molecular pump provided with an oil circulation pump device is known (see Patent Document 1).

JP 2002-61592 A

  An example of a conventional turbomolecular pump rotor is shown in FIG.

  The rotor a is made of an aluminum alloy or the like, and has a plurality of moving blades a1 projecting radially outward from the hub portion a2.

  b is a rotary shaft, and the rotary shaft b is pivotally supported by ball bearings c1, c2, etc., and is fitted to the boss portion a3 of the rotor a at the fitting portion b1, and is connected to the rotor a by a cap nut d. The rotating shaft b is fastened.

  However, the hub part a2 has a moving blade a1 protruding from the outer peripheral part of the part where the boss part a3 is formed inside.

  However, the rotor a that rotates at a high speed deforms each part due to the centrifugal force applied to the rotor blades a1 and the like.

  When the deformation of the rotor a reaches the boss part a2 having the fitting part b1 with the rotating shaft b, the shaft hole diameter of the boss part a2 is deformed and enlarged, and the fastening force with the rotating shaft b is weakened. There is a problem that slippage may occur between the rotor a and the rotating shaft b. Further, the stress generated in the rotor a by the centrifugal force becomes excessive, and when the stress exceeds the elastic limit of the material, the material yields, and in a severe case, the rotor a may break. there were.

  An object of the present invention is to provide a molecular pump rotor that solves these problems and does not weaken the fastening force of the fitting portion between the rotor and the rotating shaft.

  In order to achieve the above object, the present invention provides a turbo molecular pump or a composite molecular pump comprising a turbo molecular pump part and a thread groove pump part communicating with the turbo molecular pump part, wherein the turbo molecular pump or the rotor of the turbo molecular pump part is A rotor blade stage composed of a plurality of rotor blades is projected radially on the outer periphery of a hollow cylindrical hub portion, and a boss portion protruding in the axial direction is provided at the end portion of the hub portion so that the rotor is cup-shaped. And the rotor is fixed to the rotating shaft through the boss.

  According to the present invention, in a rotor that rotates at a high speed of a turbo molecular pump or a turbo molecular pump part of a composite molecular pump, the fitting between the rotor and the rotating shaft is not loosened by the centrifugal force of the blade, and therefore Since no slip occurs between the rotating shaft and the rotating shaft, a safe molecular pump can be provided.

  Examples of the best mode for carrying out the present invention are shown below.

  A first embodiment of the present invention will be described with reference to FIG.

  FIG. 1 is a longitudinal sectional view of a rotor 1 of a turbo molecular pump according to this embodiment.

  The rotor 1 is made of an aluminum alloy or the like, and has a large number of blades 1b projecting radially and in multiple stages on the outer periphery of a hollow cylindrical hub portion 1a.

  A boss portion 1c is provided at the lower end portion of the rotor 1 so as to protrude in the axial direction, and the rotary shaft 2 is fitted and locked in the shaft hole 1d of the boss portion 1c.

  The rotor 1 is formed in a cup shape with the hub portion 1a and the boss portion 1c, and the multistage rotor blade row is not provided on the boss portion 1c, and the inside of the hub portion 1a is a hollow portion. It protrudes only at the outer periphery.

  3 is a cap nut, 4 is a spacer, 5a and 5b are ball bearings, respectively.

  Next, a method of using the rotor 1 of the turbo molecular pump of this embodiment and the effects thereof will be described.

  The rotor 1 is supported in a turbo molecular pump case (not shown) via ball bearings 5a and 5b that support the rotating shaft 2, and is rotated at high speed by a motor (not shown).

  The rotary shaft 2 is fitted to the rotor 1 in a shaft hole 1d provided in the boss portion 1c, and the rotary shaft 2 and the rotor 1 are fastened and fixed by a cap nut 3 that is screwed into the screw portion 2a at the tip of the rotary shaft 2. .

  When the rotor 1 rotates at a high speed, the centrifugal force of the moving blade 1b can be absorbed to some extent as a hoop tension in the hub portion 1a. Therefore, the deformation in the boss portion 1c is alleviated, and the shaft hole portion 1d and the rotating shaft 2 can be prevented from loosening.

  A second embodiment of the present invention will be described with reference to FIG.

  FIG. 2 is a longitudinal sectional view of the rotor 11 of the composite molecular pump of the present embodiment, wherein 12 is a turbo molecular pump part rotor and 13 is a thread groove pump part rotor.

  The rotor 11 is made of an aluminum alloy or the like, and the rotor 12 of the turbo molecular pump part has a large number of blades 11b projecting radially and in multiple stages on the outer periphery of a hollow cylindrical hub part 11a.

  The thread groove pump portion rotor 13 is composed of a disk-shaped disk portion 13a and a cylindrical rotor portion 13b, and the disk portion 13a is arranged on the outer periphery of the hollow cylindrical hub portion 11a. It is connected to the lower part of the moving blade stage composed of the blade 11b.

  The rotor portion 13b is directly connected to the disk portion 13a and protrudes downward in a cylindrical shape. A screw groove (not shown) is formed on the outer peripheral portion of the rotor portion 13b. It operates as a thread groove pump in combination with a stator (not shown) that is installed on the outer peripheral portion of 13b so as to be opposed to each other at a narrow interval.

  A boss portion 11c is provided in the lower end portion of the cylindrical hub portion 11a so as to protrude in the axial direction, and the rotor 12 of the turbo molecular pump portion is formed in a cup shape.

  In this way, the rotor blade stage of the turbo molecular pump part composed of a large number of rotor blades 11b and the disk-like disk part 13a in which the rotor part 13b of the thread groove pump part protrudes downward are a hollow cylindrical hub part 11a. The centrifugal force generated in the rotor blade 11b and the disk portion 13a is absorbed to some extent as the hoop tension in the hub portion 11a, and the boss portion 11c and the rotary shaft 2 are fitted to each other. Will not loosen.

  A third embodiment of the present invention will be described with reference to FIG.

  FIG. 3 is a longitudinal sectional view of the rotor 21 of the turbo molecular pump of this embodiment.

  The rotor 21 of the turbo molecular pump has a disk portion 22 projecting outward from the outer peripheral portion of the hollow cylindrical hub portion 21a at the end portion, that is, the lower end portion of the hollow cylindrical hub portion 21a. A cylindrical auxiliary hub portion 21b is vertically suspended from the outer peripheral portion of the hub portion 21a and the outer peripheral portion of the auxiliary hub portion 12b.

  The portion where the rotor blade 23 is projected in this way is the outer peripheral portion of the hub portion 21a and the auxiliary hub portion 21b, and the boss portion 21c into which the rotating shaft 2 is fitted at the lower end portion of the hub portion 21a is the auxiliary portion. Since the centrifugal force generated in the moving blade 23, the hub portion 21a, and the auxiliary hub portion 21b is reduced, the influence on the boss portion 21c is reduced, so that the boss portion 21c and the rotating shaft are arranged. 2 can be prevented from loosening.

  A fourth embodiment of the present invention will be described with reference to FIG.

  FIG. 4 is a longitudinal sectional view of the rotor 31 of the turbo molecular pump of this embodiment.

  The present embodiment is different from the first embodiment in that the fixing means for the rotor 31 and the rotary shaft 7 is a flange connection.

  That is, the rotor 31 has a large number of blades 31b projecting radially and in multiple stages on the outer periphery of a hollow cylindrical hub portion 31a, and a boss portion 31c projects in the axial direction at the lower end portion of the hub portion 31a. Is formed.

  The boss portion 31c is formed with a first flange surface 7a having a plurality of fastening screw holes 8a on the lower surface, and a locking recess 7a1 is formed in a circular hole shape at the center of the first flange surface 7a. Has been.

  A second flange surface 7b that can be engaged with the first flange surface 7a is formed on the upper surface of the other rotary shaft 7, and a locking projection 7b1 is formed at the center of the second flange surface 7b. Projected in a circular bar shape.

  Thus, when the first flange surface 7a and the second flange surface 7b are engaged with each other, the locking recess 7a1 and the locking projection 7b1 are fitted, and the rotor 31 and the rotary shaft 7 are connected. Always engage concentric.

  Since the first flange surface 7a and the second flange surface 7b are fastened and fixed by the plurality of bolts 8b, the centrifugal force applied to the rotor blade 31b is the first flange surface on which the rotor 31 and the rotary shaft 7 are engaged. 7a and the second flange surface 7b are not adversely affected.

  The fixing means for the rotor 31 and the rotary shaft 7 by the engagement of the first flange surface 7a and the second flange surface 7b of this embodiment may be applied to the second embodiment or the third embodiment.

  The present invention is applied to a turbomolecular pump rotor used for generating a vacuum in a pressure range from a medium vacuum to a high vacuum.

It is a longitudinal cross-sectional view of the rotor of the turbo-molecular pump of Example 1 of this invention. 4 is a longitudinal sectional view of a rotor of a complex molecular pump of Example 2. FIG. 6 is a longitudinal sectional view of a rotor of a turbo molecular pump of Example 3. FIG. 6 is a longitudinal sectional view of a rotor of a turbo molecular pump of Example 4. FIG. It is a longitudinal cross-sectional view of the rotor of the conventional turbo molecular pump.

Explanation of symbols

1, 11, 21, 31 Rotor 1a, 11a, 21a, 31a Hub portion 1b, 11b, 23, 31b Rotor blade 1c, 11c, 21c, 31c Boss portion 2, 7 Rotating shaft 3 Nut 7a First flange surface 7a1 Locking Concave part 7b Second flange surface 7b1 Locking convex part 13 Thread groove pump part rotor 21b Auxiliary hub part 22 Disk part

Claims (6)

  In a turbomolecular pump, or a complex molecular pump comprising a turbomolecular pump section and a thread groove pump section communicating with the turbomolecular pump section, the turbomolecular pump or the rotor of the turbomolecular pump section includes a moving blade stage composed of a plurality of moving blades. A radial cylindrical protrusion is provided on the outer periphery of the hollow cylindrical hub portion, and a boss portion protruding in the axial direction is provided at the end portion of the hub portion to form the rotor in a cup shape. A rotor of a molecular pump that fixes the rotor to a rotating shaft.   The boss portion is provided with a shaft hole into which the rotating shaft is fitted, and a screw portion is provided at a tip portion of the rotating shaft that is inserted through the shaft hole, and the rotor is rotated using a nut that is screwed into the screw portion. The rotor of the molecular pump according to claim 1, wherein the rotor is configured to be fastened to a shaft.   A first flange surface having a plurality of fastening screw holes is formed on an end surface portion of the boss portion, and a second flange surface that can be engaged with the first flange surface is formed on an upper end portion of the rotating shaft. 2. The molecular pump rotor according to claim 1, wherein the first flange surface and the second flange surface are fastened by using a bolt of 5 to secure the rotor to the rotating shaft. A circular locking recess is provided at the center of the first flange surface, and a circular locking protrusion is provided at the center of the second flange surface to provide a first flange surface and a second flange surface. The rotor of the molecular pump according to claim 3, wherein the engaging recess and the engaging protrusion are fitted to each other when engaged with each other.   5. The cylindrical thread groove pump part rotor is continuously provided on the outer peripheral part of the hollow cylindrical hub part, following the rotor blade stage of the turbo molecular pump part. 6. Molecular pump rotor.   A disk part is projected outwardly from the end part of the outer peripheral part of the hollow cylindrical hub part, and a cylindrical auxiliary hub part is provided from the outer edge part of the disk part. The rotor of the molecular pump of any one of Claims 1 thru | or 4 which provided the blade stage which consists of a some blade on the outer peripheral part of this.

Images