JP2010144740A - Vibration proof structure for vacuum pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vibration-proof structure for a vacuum pump suitable to reduce microvibration of a vacuum device caused by operation of a vacuum pump. <P>SOLUTION: A vibration-proof structure for a vacuum pump P is connected to the chamber C of a vacuum device M via a mechanical damper D. The mechanical damper D includes a tubular bellows 2 for maintaining the boundary between the atmosphere and vacuum, flange sections 3A, 3B fixed to both ends of the bellows 2, and a tubular vibration damping member 4 placed between the flange sections at both ends. One flange section 3A is connected to the chamber C and the other flange section 3B is connected to an air suction opening PS of the vacuum pump P. Irregularity sections 5-1, 5-2 are placed between the flange sections 3A, 3B and the vibration damping member 4. The flange section 3B and the vibration damping member 4 abut on each other via the irregularity sections. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a vibration isolation structure for a vacuum pump connected to a chamber of an electron microscope or other vacuum apparatus.

  For example, an electron microscope is provided with a chamber for setting an observation sample. A vacuum pump is connected to this chamber via a mechanical damper, and the inside of the chamber is evacuated by the vacuum pump. The mechanical damper is provided in order to prevent vibration generated by the operation of the vacuum pump from being transmitted to the electron microscope side.

  As described above, a connection structure for connecting a vacuum pump and a chamber of a vacuum apparatus such as an electron microscope via a mechanical damper is disclosed in Patent Document 1, for example. As shown in FIG. 5, the mechanical damper used in the document 1 includes a cylindrical bellows 2 that maintains the boundary between air and vacuum, flange portions 3A and 3B attached to both ends of the bellows 2, and flange portions 3A at both ends. And a cylindrical elastic member made of silicone rubber interposed as a vibration damping member 4 between 3B.

  And while connecting one flange part 3A of this mechanical damper D to the chamber C of the vacuum apparatus M and connecting the other flange part 3B to the inlet port PS of the vacuum pump P, the inner space of the bellows 2 is passed through. The vacuum pump P and the chamber C communicate with each other, and the operation of the vacuum pump P is performed in this state, whereby the gas in the chamber C is exhausted to the outside through the inner space of the bellows 2 and the inside of the vacuum pump P.

  By the way, according to the conventional connection structure as described above, the vibration damping effect of the mechanical damper D can be enhanced by reducing the spring constant of the elastic member made of silicone rubber provided as the vibration damping member 4. .

  However, if the spring constant of the elastic member (vibration damping member 4) of the mechanical damper D is made too small, the rigidity of the elastic member decreases, and the elasticity increases as the degree of vacuum in the chamber C and the inner space of the bellows 2 increases. The member cannot withstand the atmospheric pressure and contracts, causing a problem that the vacuum pump P is drawn toward the chamber C side.

  From the above, for the purpose of enhancing the vibration damping effect, there is a certain limit to reducing the spring constant of the elastic member (vibration damping member 4) of the mechanical damper D, and the elastic member exceeds the limit. The spring constant cannot be reduced. In addition, the elastic member of the mechanical damper D is adhered and adhered to the metallic flange portion 3B connected to the suction port PS side of the vacuum pump P and the metallic flange portion 3A connected to the chamber C side. Therefore, the vibration of the vacuum pump P is easily transmitted to the vacuum device M through the elastic member. For this reason, micro-vibration that cannot be sufficiently damped unless it is an elastic member with a minimum spring constant exceeding the limit, for example, micro-vibration with an amplitude of nanometer order or less, can be damped by the elastic member of the mechanical damper D. However, there is a problem that such fine vibration propagates to the vacuum device M side through the elastic member of the mechanical damper D, and the vacuum device M slightly vibrates.

  A motor for rotating the rotor is built in the vacuum pump P, and the stator of the motor receives a reaction force of the rotor rotation and slightly vibrates. Since such slight vibration propagates to the vacuum apparatus M side through the elastic member of the mechanical damper D as described above, as long as the vacuum pump P is operated, the fine vibration of the vacuum apparatus M is not lost.

  In particular, in the field of electron microscopes that perform precise observation at the atomic level using an electron beam or the like, it is an issue to reduce such fine vibrations as the performance improves. This also applies to other vacuum devices other than the electron microscope that performs the same precise work.

JP 2002-295581 A

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a vacuum pump vibration isolation structure suitable for reducing fine vibrations of a vacuum apparatus accompanying the operation of the vacuum pump. There is.

  In order to achieve the above object, the present invention provides a vibration isolating structure for a vacuum pump connected to a chamber of a vacuum apparatus via a mechanical damper, wherein the mechanical damper has a cylindrical shape that maintains a boundary between air and vacuum. A bellows, a flange attached to both ends of the bellows, and a cylindrical vibration damping member interposed between the flanges on both ends, the one flange connected to the chamber, and the other flange It has a structure in which a portion is connected to the suction port portion of the vacuum pump, and an uneven portion is provided between the flange portion and the vibration damping member.

  The concavo-convex portion is formed by providing a notch in the upper end surface of the vibration damping member facing the lower surface of the flange portion, or is cut out in the lower end surface of the vibration absorbing member facing the upper surface of the flange portion. And may be formed.

  The concavo-convex portion is formed by providing a protrusion on the lower surface of the flange portion facing the upper end surface of the vibration damping member, or a protrusion is provided on the upper surface of the flange portion facing the lower end surface of the vibration damping member. It may be formed.

  In the present invention, the uneven portion is provided between the flange portion and the vibration damping member. For this reason, since the vibration damping member abuts on the flange portion through the uneven portion, the contact area between the vibration damping member and the flange portion is reduced, and the rotational rigidity around the vacuum pump radial axis of the mechanical damper is weakened. Since the vibration component in the direction (around the vacuum pump radial axis) can be damped, the amount of vibration propagation with an amplitude of nanometer order or less from the vacuum pump to the vacuum device is reduced. There are effects such as the ability to reduce micro vibrations.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is an explanatory view of an embodiment of a vacuum pump vibration-proof structure of the present invention, FIG. 2A is a top view of a vibration damping member constituting a mechanical damper employed in the vacuum pump vibration-proof structure of FIG. ) Is a cross-sectional view of the vibration damping member taken along the line bb, and (c) is a bottom view of the vibration damping member.

  This vacuum pump vibration isolation structure is a vibration isolation structure of a vacuum pump P connected to a chamber C of a vacuum apparatus M such as an electron microscope via a mechanical damper D as shown in FIG. A pump TP or other vacuum pump is applied. In the present embodiment, a known turbo molecular pump TP is employed as an example of the vacuum pump P.

  Although not shown, the turbo molecular pump TP is positioned in a multistage manner between the rotor blades, a rotor that is rotationally driven by a motor, a plurality of rotor blades provided in multiple stages on the outer peripheral surface of the rotor, and a pump case 1. And fixed stator blades. Then, the rotor blades rotate around the rotation center axis of the rotor by the rotation of the rotor, and gas molecules are sequentially transferred and exhausted by the rotating rotor blades and the fixed stator blades.

  The mechanical damper D is a means for attenuating mechanical vibration generated by the operation of the vacuum pump P. The mechanical damper D of the present embodiment includes a cylindrical bellows 2 that maintains a boundary between vacuum and the atmosphere, and a bellows 2. It is comprised by the flange parts 3A and 3B attached to the upper and lower ends by welding etc., and the cylindrical vibration damping member 4 interposed between these upper and lower flange parts 3A and 3B.

  Further, in the mechanical damper D of this embodiment, the upper flange portion 3A is attached to the chamber C of the vacuum apparatus M, and the intake port PS of the vacuum pump P is attached to the lower flange portion 3B. It has become.

  Further, a first uneven portion 5-1 is provided between the lower surface S1 of the upper flange portion 3A and the upper end surface S2 of the vibration damping member 4 facing the upper flange portion 3A. The vibration damping member 4 is configured to come into contact with the upper flange portion 3A.

  In particular, in the present embodiment, as a specific configuration example of the first uneven portion 5-1, two notches 5A and 5B are provided on the upper end surface S2 of the vibration damping member 4 as shown in FIG. Thus, a configuration in which the first uneven portion 5-1 is formed is adopted. Further, the two first cutouts 5A and 5B are configured to be opposed to each other around the central axis L of the vibration damping member 4 by 180 degrees. For this reason, as shown in FIG. 2A, the contact surfaces of the vibration damping member 4 and the flange portion 3A are similarly opposed to each other by 180 degrees.

  In other words, the vacuum pump vibration isolating structure of the present embodiment is configured such that the vibration damping member 4 comes into contact with the upper flange portion 3A via the first uneven portion 5-1 formed by the notches 5A and 5B. Thus, the contact area between the vibration damping member 4 and the flange portion 3A is reduced, the rotational rigidity of the mechanical damper D around the vacuum pump radial axis is actively weakened, and the vibration in that direction (around the vacuum pump radial axis) The component is attenuated.

  Similarly, between the upper surface S3 of the lower flange portion 3B and the lower end surface S4 of the vibration damping member 4 opposed thereto, the second uneven portion 5-2 formed by the notches 5A and 5B described above is provided. The vibration attenuating member 4 is in contact with the lower flange portion 3B through the second uneven portion 5-2.

  Further, the notches 5A and 5B forming the first uneven portion 5-1 and the notches 5A and 5B forming the second uneven portion 5-2 are 90 degrees around the central axis L of the vibration damping member 4. They are arranged at equal pitch intervals that are shifted one by one. Accordingly, as shown in FIGS. 2A and 2C, the contact surfaces of the vibration damping member 4 and the flange portions 3A and 3B are provided so as not to overlap each other in the vertical direction.

  Of the components of the mechanical damper D of the present embodiment, the bellows 2 and the flange portions 3A and 3B are made of metal, and the vibration damping member 4 is made of silicone rubber as an elastic member. The bellows 2, the flange portions 3A and 3B, and the vibration damping member 4 may be formed.

  Next, the operation of the vacuum pump vibration-proof structure configured as described above will be described with reference to FIG.

  When the operation of the vacuum pump P is started and the rotor is rotated at a high speed by a motor (not shown) in the vacuum pump P, the operation of sequentially transferring and exhausting gas molecules between the rotor blade rotating integrally with the rotor and the fixed stator blade is performed. Done.

  Thereby, the suction port part PS side of the vacuum pump P becomes a low pressure, and the gas molecules in the chamber C of the vacuum device M pass through the inner space of the bellows 2 of the mechanical damper D to the suction port part PS of the vacuum pump P. Then, it is exhausted to the outside by the vacuum pump P.

  By the way, it is inevitable that a slight vibration accompanying the rotation of the rotor is generated in the vacuum pump P during the operation of the vacuum pump P. The slight vibration is inevitably generated from the intake port PS of the vacuum pump P through the mechanical damper D. It tries to propagate to the vacuum device M.

  However, in the vacuum pump vibration isolating structure of the present embodiment, the flange portions 3A and 3B and the vibration damping member 4 are damped by the contact structure between the flange portions 3A and 3B and the vibration damping member 4 via the concave and convex portions 5-1 and 5-2. Since the contact area with the member 4 is reduced and the rotational rigidity of the mechanical damper D around the vacuum pump radial axis is actively weakened, the vibration component in that direction (vacuum pump radial axis) is attenuated, and the vacuum device M The amount of propagation of micro-vibration to is reduced.

  In the above embodiment, the notches 5A and 5B are formed in the lower end surface S4 of the vibration damping member 4 as shown in FIGS. 2B and 2C, so that the lower end surface S4 and the lower flange of the vibration damping member 4 are formed. Although the configuration in which the second uneven portion 5-2 is provided between the upper surface S3 of the portion 3B is adopted, the second uneven portion 5-2 is as shown in FIGS. 3 (a) and 3 (b). You may comprise so that it may provide by forming two protrusion 5D, 5E in the upper surface S3 of the lower flange part 3B facing the lower end surface S4 of the vibration damping member 4. FIG. Although the illustration is omitted in this respect, the same applies to the first uneven portion 5-1.

  Further, the first concavo-convex portion 5-1 is formed by inserting a spacer (not shown) between the upper end surface S2 of the vibration damping member 4 and the lower surface S1 of the flange portion 3A opposite to the upper end surface S2. Also good. The same applies to the second uneven portion 5-2.

  Furthermore, in the said embodiment, the 1st uneven | corrugated | grooved part 5-1 and the 2nd uneven | corrugated | grooved part 5-2 are formed by two notches 5A and 5B like FIG. 2 (a) (b) (c). Although the configuration is adopted, the number of notches is not limited to two, but can be three (notches 5A, 5B, 5C) as shown in FIGS. Similarly, the number of projections 5D and 5E in FIGS. 3A and 3B is not limited to two.

  In the above embodiment, the configuration example in which the turbo molecular pump TP is adopted as an example of the vacuum pump P has been described. However, the vacuum pump vibration isolating structure of the present invention is a vacuum pump other than the turbo molecular pump such as a thread groove pump, for example. It can also be applied to.

Sectional drawing of the vacuum pump vibration proof structure which is one Embodiment of this invention. (A) is a top view of a vibration damping member constituting the mechanical damper employed in the vacuum pump vibration-proof structure of FIG. 1, (b) is a cross-sectional view taken along the line bb of the vibration damping member, and (c) is its vibration damping. It is a bottom view of a member. (A) is explanatory drawing of the vacuum pump vibration-proof structure containing other embodiment of the uneven | corrugated | grooved part provided between a vibration damping member and a flange part, (b) is the mechanical damper employ | adopted with the vacuum pump vibration-proof structure. The upper surface figure of the lower flange part which constitutes. FIG. 4 is an explanatory view of another embodiment in the case where the uneven portion between the vibration damping member and the flange portion is formed by notching, and (a) is an upper surface of the vibration damping member on which the notch is formed. FIG. 4B is a bottom view of the vibration damping member. Explanatory drawing of the conventional connection structure which connects a vacuum pump and the chamber of a vacuum device via a mechanical damper.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pump case 2 Bellows 3A, 3B Flange part 4 Vibration damping member 5-1 1st uneven part 5-2 2nd uneven part 5A, 5B, 5C Notch 5D, 5E Protrusion L Center axis line S1 upper side of vibration damping member Lower surface S2 of the vibration damping member upper end surface S3 of the vibration damping member upper surface S4 of the lower flange portion C lower end surface of the vibration damping member C Chamber G Grease D Mechanical damper M Vacuum apparatus P Vacuum pump PS Inlet port TP Turbo molecular pump

Claims (3)

A vibration-proof structure of a vacuum pump connected to a chamber of a vacuum device via a mechanical damper,
The mechanical damper includes a cylindrical bellows that maintains a boundary between air and vacuum, flange portions attached to both ends of the bellows, and cylindrical vibration damping members interposed between the flange portions on both ends, One flange portion is connected to the chamber, and the other flange portion is connected to the suction port portion of the vacuum pump.
An anti-vibration structure for a vacuum pump, wherein an uneven portion is provided between the flange portion and the vibration damping member. The concavo-convex portion is formed by providing a notch on the upper end surface of the vibration damping member facing the lower surface of the flange portion, or is notched on the lower end surface of the vibration absorbing member facing the upper surface of the flange portion. The vacuum pump vibration-proof structure according to claim 1, wherein the vacuum pump vibration-proof structure is provided. The concavo-convex portion is formed by providing a protrusion on the lower surface of the flange portion facing the upper end surface of the vibration damping member, or a protrusion is provided on the upper surface of the flange portion facing the lower end surface of the vibration damping member. The anti-vibration structure for a vacuum pump according to claim 1, wherein the anti-vibration structure is formed by:

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