JP2015127525A - Vacuum pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vacuum pump which absorbs an impact caused during rotor breakage and reduces sudden stop torque.SOLUTION: A high strength member 12 is provided at the outer periphery side of a screw stator 11. The high strength member 12 is fixed by a fixing plate 13. A gap is provided between the high strength member 12 and an inner peripheral surface 50b of a base. Both ends of the high strength member 12 respectively fit in a first annular groove 11b provided at an attachment flange 11a and a second annular groove 13a provided at the fixing plate 13. An outer peripheral surface of the high strength member 12 contacts with an outer peripheral surface of the first annular groove 11b and also contacts with an outer peripheral surface of the second annular groove 13a.

Description

  The present invention relates to a vacuum pump.

  A vacuum pump represented by a turbo molecular pump is attached to a vacuum chamber such as a dry etching apparatus or a CVD apparatus. In the turbo molecular pump, the rotor formed with the rotor blades and the rotor cylindrical part rotates at a high speed of several tens of thousands of revolutions per minute, the rotor blades and the stator blades cooperate, and the rotor cylindrical part and the screw stator cooperate. Then, a high vacuum state is created by exhausting the gas in the vacuum chamber.

  Patent Document 1 describes an invention in which gas molecules exhausted by cooperation of a rotor blade and a stator blade are exhausted while being compressed by a rotating rotor cylindrical portion and a screw stator fixed to a base. ing.

  During the use of a turbo molecular pump, the rotor may be damaged for some reason. This is called rotor destruction. When the rotor cylindrical portion is broken due to the rotor destruction and fragments are generated, the fragments are scattered and collide with a screw stator facing the rotor cylindrical portion.

JP 2003-172289 A

  In the invention described in Patent Literature 1, the screw stator is deformed in the outer peripheral direction due to the impact of the broken piece of the rotor cylindrical portion and collides with the inner peripheral surface of the base of the turbo molecular pump casing, so that the impact due to the rotor destruction is the base. There was a risk of transmission to the inner peripheral surface.

(1) A vacuum pump according to a preferred embodiment of the present invention includes a rotor cylindrical portion, a stator disposed on the outer peripheral side of the rotor cylindrical portion, and a base to which the stator is fixed, and on the outer peripheral side of the stator. Is provided with a cylindrical high-strength member made of a material having a higher specific strength than the material of the stator, and a gap is provided between the outer peripheral surface of the high-strength member and the inner peripheral surface of the base. And
(2) In a more preferred embodiment, an annular fixing plate for fixing the high-strength member to the stator is further provided, the mounting flange of the stator is provided with a first annular groove, and the fixing plate is provided with a second annular plate. A groove is provided, and both ends of the high-strength member are fitted into the first annular groove and the second annular groove, the outer peripheral surface of the high-strength member is in contact with the outer peripheral surface of the first annular groove, and the first It contacts the outer peripheral surface of 2 annular grooves, It is characterized by the above-mentioned.
(3) In a more preferred embodiment, the fixing plate is fixed to the stator by a screw member.
(4) In a more preferred embodiment, the mounting flange of the stator is provided with a third annular groove, the base is provided with a fourth annular groove, and both ends of the high-strength member are connected to the third annular groove. The outer circumferential surface of the high-strength member is fitted into each of the fourth annular grooves, is in contact with the outer circumferential surface of the third annular groove, and is in contact with the outer circumferential surface of the fourth annular groove.
(5) In a more preferred embodiment, a gap is provided between the stator and the high-strength member.
(6) In a further preferred embodiment, the high-strength member includes a fiber reinforced member, and the fibers of the fiber reinforced member are wound spirally.
(7) In a further preferred embodiment, the high-strength member is made of a fiber reinforced member, and the fibers of the fiber reinforced member are spirally wound so that the fibers cross each other and maintain a predetermined strength when viewed from the radial direction. It is characterized by being turned.

  According to the vacuum pump of the present invention, it is possible to absorb the impact when the rotor is broken and reduce the sudden stop torque.

A sectional view showing a schematic structure of a turbo-molecular pump of a 1st embodiment. The figure which shows the screw stator periphery in the turbo-molecular pump of 1st Embodiment. The figure which shows the screw stator periphery in the turbo-molecular pump of 2nd Embodiment.

In describing the vacuum pump of the present invention, a turbo molecular pump will be described as an example. In addition, this invention is applicable also to vacuum pumps, such as a molecular drag pump.
-First embodiment-
FIG. 1 is a cross-sectional view showing a schematic configuration of the turbo molecular pump 100. The rotor assembly 10 is rotatably provided in the casing 52 of the turbo molecular pump 100. The rotor assembly 10 includes a rotor 4, a shaft 5, and a rotor disk 6. The turbo molecular pump 100 is a magnetic bearing type pump, and the rotor assembly 10 is supported in a non-contact manner by an upper radial electromagnet 62, a lower radial electromagnet 64, and a thrust electromagnet 66.

  The rotor 4 is provided with a plurality of stages of rotor blades 20 and a rotor cylindrical portion 8. A plurality of stages of stator blades 44 are provided between the plurality of stages of rotor blades 20 in the axial direction, and a screw stator 11 is provided on the outer peripheral side of the rotor cylindrical portion 8. A screw groove is provided on the inner peripheral surface of the screw stator 11. On the other hand, the outer circumferential surface of the rotor cylindrical portion 8 is not provided with a thread groove.

  Each stator blade 44 is disposed on the base 50 via a spacer 58. When the casing 52 is fixed to the base 50, the stacked spacers 58 are sandwiched between the base 50 and the casing 52, and the stator blades 44 are positioned.

  The screw stator 11 is made of an aluminum alloy or the like. The screw stator 11 is attached to a recess 50 a provided in the base 50 with a bolt 30 through an attachment flange 11 a of the screw stator 11. On the outer peripheral side of the screw stator 11, a cylindrical member 12 (hereinafter referred to as a high-strength member 12) made of CFRP, which is a fiber reinforced member having a specific strength greater than that of an aluminum alloy, is disposed. The high-strength member 12 is fitted into the annular groove 11b formed in the mounting flange 11a, and is further fitted into the annular groove 13a formed in the fixing plate 13. In addition, the high strength member 12 is fixed to the screw stator 11 by fixing the fixing plate 13 to the screw stator 11 with the bolts 14. Details of the periphery of the screw stator 11 will be described later with reference to FIG.

  The base 50 is provided with an exhaust port 56, and a back pump is connected to the exhaust port 56. When the rotor assembly 10 is magnetically levitated by the upper radial electromagnet 62, the lower radial electromagnet 64, and the thrust electromagnet 66, the rotor 40 is driven to rotate at high speed by the motor 40, whereby the gas molecules on the intake port 31 side are exhausted to the exhaust port 56 side. The

  FIG. 2 is a view showing the periphery of the screw stator 11 in the turbo molecular pump 100 of the first embodiment. The screw stator 11 is provided with an annular groove 11b in a mounting flange 11a. As described above, the high-strength member 12 formed in a cylindrical shape is provided on the outer peripheral side of the screw stator 11 as in the case of the screw stator 11.

  One end of the opening of the high-strength member 12 is fitted and supported in the annular groove 11b. The other end of the opening of the high-strength member 12 is fitted into and supported by an annular groove 13 a provided in the fixed plate 13. The fixing plate 13 is not particularly limited. For example, the fixing plate 13 is formed in a cylindrical shape and is fixed to the screw stator 11 by a bolt 14. As a result, the high-strength member 12 is sandwiched and fixed between the annular groove 11 b of the screw stator 11 and the annular groove 13 a of the fixing plate 13. There is a gap s1 between the fixed plate 13 and the inner peripheral surface 50b of the base 50. Naturally, since the arrangement is as described above, a gap s0 is also provided between the outer peripheral surface of the high-strength member 12 and the inner peripheral surface of the base 50. Further, the gap s0 is larger than the gap s1. Thus, by providing the high-strength member 12 on the outer peripheral side of the screw stator 11, the screw stator 11 is deformed in the outer peripheral direction when the rotor breaks down and the screw stator 11 receives the outer peripheral force from the rotor cylindrical portion 8. This can be suppressed. As a result, it is possible to reduce the amount of impact transmitted to the inner peripheral surface 50 b of the base 50 due to the rotor destruction received by the screw stator 11.

  The outer peripheral surface of the annular groove 11b of the screw stator 11 and the outer peripheral surface of the high-strength member 12 are in contact with each other. Similarly, the outer peripheral surface of the annular groove 13a of the fixing plate 13 and the outer peripheral surface of the high-strength member 12 are in contact with each other. By doing so, both ends of the opening of the high-strength member 12 and the outer peripheral surface near the opening are supported and fixed by the annular groove 11 b of the screw stator 11 and the annular groove 13 a of the fixing plate 13. Thereby, when the rotor breaks down and the screw stator 11 receives a force in the outer peripheral direction from the rotor cylindrical portion 8, it is possible to mainly suppress deformation of both ends of the opening of the screw stator 11 in the outer peripheral direction.

  On the other hand, the inner peripheral surface of the annular groove 11b of the screw stator 11 and the inner peripheral surface of the high-strength member 12 are not in contact with each other, and the gap s2 is vacant. Similarly, the inner peripheral surface of the annular groove 13a of the fixing plate 13 and the inner peripheral surface of the high-strength member 12 are not in contact with each other, and the gap s3 is vacant. Accordingly, the central portion 11d of the screw stator 11 is allowed to be deformed, and the energy for breaking the rotor can be consumed by the deformation. Furthermore, a concave portion 11e is provided on the outer peripheral surface of the screw stator 11, and further widens the gap s4 between the screw stator 11 and the high-strength member 12. As a result, the central portion 11d of the screw stator 11 is further easily deformed, and the energy for breaking the rotor is easily consumed. The gap s4 between the screw stator 11 and the high-strength member 12 is set so that the fixing plate 13 does not come into contact with the inner peripheral surface 50b of the base 50 due to the deformation of the central portion 11d of the screw stator 11.

  The high strength member 12 is made of a fiber reinforced member such as CFRP. When the rotor breaks, the high-strength member 12 is mainly subjected to a force in the outer peripheral direction. The fibers of the fiber reinforced member constituting the high-strength member 12 in this embodiment are wound at least in a spiral shape to maintain a predetermined strength so that the force can be received. In addition, although there are a right-handed winding and a left-handed winding in the spiral winding direction, it is preferable that both a right-handed winding and a left-handed winding are included. When both right-handed and left-handed are included, the fibers cross each other when viewed from the radial direction, and one fiber supports the other fiber, so that the strength against the force is improved.

As mentioned above, according to 1st Embodiment, there exist the following effects.
(1) One end of the opening of the high-strength member 12 is fitted and supported in the annular groove 11b. The other end of the opening of the high-strength member 12 is fitted into and supported by an annular groove 13 a provided in the fixed plate 13. The fixing plate 13 is fixed to the screw stator 11 with bolts 14. There is a gap s1 between the fixed plate 13 and the inner peripheral surface 50b of the base 50.
Thus, by providing the high-strength member 12 on the outer peripheral side of the screw stator 11, when the rotor stator breaks down and the screw stator 11 receives a force in the outer peripheral direction from the rotor cylindrical portion 8, the screw stator 11 is deformed in the outer peripheral direction. As a result, it is possible to reduce the amount of impact due to rotor breakage received by the screw stator 11 from the rotor cylindrical portion 8 to the inner peripheral surface 50b of the base 50. As a result, the sudden stop torque when the rotor is broken can be reduced.

(2) The outer peripheral surface of the annular groove 11b of the screw stator 11 and the outer peripheral surface of the high-strength member 12 are in contact with each other. Similarly, the outer peripheral surface of the annular groove 13a of the fixing plate 13 and the outer peripheral surface of the high-strength member 12 are in contact with each other. By abutting in this way, both ends of the opening of the high-strength member 12 and the outer peripheral surface near the opening are supported and fixed by the annular groove 11 b of the screw stator 11 and the annular groove 13 a of the fixing plate 13. Accordingly, it is possible to mainly suppress the deformation of the both ends of the opening of the screw stator 11 in the outer peripheral direction when the rotor stator breaks and the screw stator 11 receives the outer peripheral force from the rotor cylindrical portion 8.

(3) On the other hand, the inner peripheral surface of the annular groove 11b of the screw stator 11 and the inner peripheral surface of the high-strength member 12 are not in contact with each other, and the gap s2 is vacant. Similarly, the inner peripheral surface of the annular groove 13a of the fixing plate 13 and the inner peripheral surface of the high-strength member 12 are not in contact with each other, and the gap s3 is vacant. As a result, the central portion 11d of the screw stator 11 is allowed to be deformed, and the energy for breaking the rotor can be consumed by the deformation. Furthermore, a concave portion 11e is provided on the outer peripheral surface of the screw stator 11, and further widens the gap s4 between the screw stator 11 and the high-strength member 12. Accordingly, the central portion 11d of the screw stator 11 is further easily deformed, and the energy for breaking the rotor is easily consumed. The above-described gap s4 is set so that the fixed plate 13 does not contact the inner peripheral surface of the base 50 due to the deformation of the central portion 11d of the screw stator 11.

(4) The fixing plate 13 is fastened to the screw stator 11 by bolts 14 that are screw members.
This facilitates disassembly during repair or the like.

(5) The high strength member 12 is made of CFRP which is a fiber reinforced member. Since the fiber reinforced member such as CFRP is lighter than the aluminum alloy that is the material of the screw stator 11, the turbo molecular pump 100 can be reduced in weight. Further, the fiber direction of the CFRP is designed so as to hold a predetermined strength and receive the force on the outer peripheral side by including a spiral fiber direction. In addition, although there are a right-handed winding and a left-handed winding in the spiral winding direction, it is preferable that both a right-handed winding and a left-handed winding are included. When both right-handed and left-handed are included, the fibers cross each other when viewed from the radial direction, and one fiber supports the other fiber, so that the strength against the force is improved.

-Second embodiment-
FIG. 3 is a view showing the periphery of the screw stator 11 in the turbo molecular pump 100 of the second embodiment. The description of the same configuration as that of the first embodiment is omitted.

  The turbo molecular pump 100 of the second embodiment does not have a fixing plate for fixing the high-strength member 12. In the present embodiment, an annular groove 50 d is formed on the bottom surface 50 c of the base 50. Since the bottom surface 50c of the base 50 has higher rigidity than the inner peripheral surface 50b of the base 50, it can withstand the impact of rotor destruction. The high-strength member 12 is fitted into an annular groove 50d formed in the bottom surface 50c of the base 50, and further fitted into an annular groove 11b formed in the mounting flange 11a of the screw stator 11. In addition, the high-strength member 12 is fixed by being sandwiched between the screw stator 11 and the bottom surface 50 c of the base 50. A gap s5 is provided between the high-strength member 12 and the inner peripheral surface 50b of the base 50.

  The outer peripheral surface of the annular groove 11b of the screw stator 11 and the outer peripheral surface of the high-strength member 12 are in contact with each other. Similarly, the outer peripheral surface of the annular groove 50d of the base 50 is in contact with the outer peripheral surface of the high-strength member 12. Further, a gap s <b> 2 is provided between the inner peripheral surface of the annular groove 11 b of the screw stator 11 and the inner peripheral surface of the high-strength member 12. Similarly, a gap s6 is provided between the inner peripheral surface of the annular groove 50d of the base 50 and the inner peripheral surface of the high-strength member 12. Furthermore, a concave portion 11e is provided on the outer peripheral surface of the screw stator 11, and further widens the gap s4 between the screw stator 11 and the high-strength member 12.

  As mentioned above, according to 2nd Embodiment, there exists an effect similar to 1st Embodiment. Note that the high-strength member 12 of the second embodiment is partially formed with a through hole, a notch, and the like, and connects the internal exhaust system of the turbo molecular pump 100 and the exhaust port 56.

  In the first and second embodiments described above, the gap s4 is provided between the screw stator 11 and the high-strength member 12, but the gap s4 may not be provided. That is, the screw stator 11 and the high strength member 12 may be brought into contact with each other. By doing so, the screw stator 11 is not easily deformed, but the gap between the outer peripheral surface of the high-strength member 12 and the inner peripheral surface of the base 50 is increased by the amount that the gap s4 is not provided. Thus, it is possible to prevent the impact due to the rotor breaking from being transmitted to the inner peripheral surface 50b of the base 50.

  In the first embodiment and the second embodiment described above, CFRP is used as the fiber reinforced member, but other fiber reinforced members such as GFRP have the same effect.

  In the first and second embodiments described above, the high-strength member is made of CFRP, which is a fiber-reinforced member, but may be made of titanium or the like.

  In the vacuum pump of the present invention, a thread groove may be provided on one of the inner peripheral surface of the stator and the outer peripheral surface of the rotor cylindrical portion. Therefore, in the first embodiment and the second embodiment described above, a stator having a thread groove provided on the inner peripheral surface, that is, a screw stator is used, but instead of providing a screw groove on the inner peripheral surface of the stator. A screw groove can also be provided on the outer peripheral surface of the rotor cylindrical portion.

  The above description is merely an example, and the present invention is not limited to the above embodiment.

4: Rotor, 5: Shaft, 6: Rotor disc, 8: Rotor cylindrical part,
10: Rotor assembly, 11: Screw stator, 11a: Mounting flange,
11b: annular groove, 11d: central portion, 11e: concave portion, 12: high strength member,
13: fixing plate, 13a: annular groove, 14: bolt, 20: rotor blade,
30: Bolt, 31: Inlet, 40: Motor, 44: Stator blade
50: base, 50a: recess, 50b: inner peripheral surface, 50c: bottom surface,
50d: annular groove, 52: casing, 56: exhaust port, 58: spacer,
62: Upper radial electromagnet, 64: Lower radial electromagnet, 66: Thrust electromagnet,
s0 to s6: clearance, 100: turbo molecular pump

Claims (7)

A rotor cylinder,
A stator disposed on an outer peripheral side of the rotor cylindrical portion;
A base on which the stator is fixed,
A cylindrical high-strength member made of a material having a specific strength higher than that of the stator is provided on the outer peripheral side of the stator,
A vacuum pump in which a gap is provided between an outer peripheral surface of the high-strength member and an inner peripheral surface of the base. The vacuum pump according to claim 1, wherein
An annular fixing plate for fixing the high-strength member to the stator;
The mounting flange of the stator is provided with a first annular groove,
The fixing plate is provided with a second annular groove,
Both ends of the high-strength member are fitted in the first annular groove and the second annular groove,
A vacuum pump in which an outer peripheral surface of the high-strength member is in contact with an outer peripheral surface of the first annular groove and is in contact with an outer peripheral surface of the second annular groove. The vacuum pump according to claim 2,
The fixing plate is a vacuum pump fixed to the stator by a screw member. The vacuum pump according to claim 1, wherein
The mounting flange of the stator is provided with a third annular groove,
A fourth annular groove is provided on the bottom surface of the base,
Both ends of the high-strength member are fitted in the third annular groove and the fourth annular groove,
A vacuum pump in which an outer peripheral surface of the high-strength member is in contact with an outer peripheral surface of the third annular groove and is in contact with an outer peripheral surface of the fourth annular groove. In the vacuum pump as described in any one of Claims 1-4,
A vacuum pump in which a gap is provided between the stator and the high-strength member. In the vacuum pump as described in any one of Claims 1-5,
The high-strength member includes a fiber reinforced member, and the fiber of the fiber reinforced member is a vacuum pump wound spirally. The vacuum pump according to claim 6,
The high-strength member comprises a fiber reinforced member,
The fiber of the fiber reinforced member is a vacuum pump that is spirally wound so that the fibers cross each other and maintain a predetermined strength when viewed from the radial direction.

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