JP2014084825A - Vacuum pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten the lengths of rotating shafts in a two-shaft vacuum pump provided with magnetic bearings.SOLUTION: A vacuum pump comprises: two rotating shafts that are arranged in parallel and synchronously rotate on two respective axes; and magnetic bearings that support the two rotating shafts at both ends of the respective rotating shafts. The magnetic bearings comprise: bearing rotors that have a cylindrical cup-like shape, include a magnetic material, and rotate together with the rotating shafts; first electromagnets that are arranged in parallel with the axes inside the bearing rotors; second electromagnets that are arranged perpendicularly to the axes inside the bearing rotors and generate magnetic attraction force in the direction of the axes at both ends of the rotating shafts.

Description

  The present invention relates to a magnetic bearing for a vacuum pump.

  In many cases, a roughing pump such as a dry vacuum pump used in a semiconductor manufacturing apparatus is connected to an exhaust pipe having a long path from the process chamber toward the downstream side. Moreover, when a semiconductor manufacturing apparatus is enlarged, large-diameter piping is required. However, a long-path pipe having a large diameter itself has a large volume of gas. For this reason, when increasing the size of the semiconductor manufacturing apparatus, it is necessary to increase the capacity of the coarse grinding pump.

  On the other hand, in recent years, the process conditions for semiconductor manufacturing have become finer, and techniques for finely controlling the gas exhaust amount from the process chamber and the gas flow rate in the process chamber have become important. Such control is generally controlled only by opening and closing a flow rate control valve installed in the pipe. For such flow rate control, it is originally preferable to install a small coarse grinding pump in the vicinity of the process chamber and control the pressure with this small coarse grinding pump. However, in order to install the pump directly in the process chamber, the pump needs to be small. For this reason, it is required to reduce the size of the pump while ensuring the required capacity.

JP 2000-329084 A Japanese Patent Laid-Open No. 10-141273

  In order to reduce the size of the pump, it is effective to increase the rotational speed. However, in the conventional biaxial pump of the magnetic bearing mounting type, the length of the rotating shaft tends to be longer than that of the normal ball bearing bearing mounting type of pump. For this reason, when the pump is rotated at a high speed, the influence of vibration due to the rigid body mode of the rotating shaft becomes large, and there is a possibility that contact occurs between two shafts arranged in parallel. For this reason, there is a need for a technique that can shorten the length of the rotating shaft in a magnetic bearing mounting type biaxial vacuum pump.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as, for example, the following forms.

  The first aspect of the present invention is provided as a vacuum pump. This vacuum pump is provided in parallel, and includes two rotating shafts that rotate synchronously around two axes, and magnetic bearings that support the rotating shafts at both ends of the two rotating shafts. The magnetic bearing has a cylindrical cup-like shape, includes a magnetic material, and rotates together with the rotating shaft. The first electromagnet disposed parallel to the axis inside the bearing rotor, and the bearing rotor. A second electromagnet arranged perpendicular to the axis, the second electromagnet generating a magnetic attractive force in the direction of the axis at both ends of the rotating shaft.

According to such a vacuum pump, since the second electromagnet is arranged inside the cylindrical cup-shaped bearing rotor to constitute the axial bearing, compared with the thrust magnetic bearing in which the electromagnet is arranged on both sides of the disk-shaped magnetic body. Thus, the length of the rotating shaft can be shortened by the length of the disk-shaped magnetic body in the axial direction. As a result, when the vacuum pump is rotated at a high speed, contact between the two rotating shafts can be suppressed. That is, the rotation speed can be increased by that much.

  As a second aspect of the present invention, the vacuum pump according to the first aspect may include a motor for applying a rotational driving force to at least one of the two rotational shafts. The motor may be disposed at a position outside the bearing rotor in a direction perpendicular to the axis, and at least a part of the motor and the magnetic bearing overlap in the direction of the axis. According to this embodiment, the length of the rotating shaft is shortened by an amount corresponding to the overlap of the motor and the magnetic bearing in the direction of the axis, compared to the conventional configuration in which the motor and the magnetic bearing are arranged in the direction of the axis. it can.

  As a third mode of the present invention, in the second mode, the length in the direction of the axis of the first device that is one of the motor and the magnetic bearing is the axis of the second device that is the other device. The second device is disposed in a position overlapping with the first device over the entire length of the second device in the axial direction in the axial direction. May be. According to this mode, the effect of the second mode can be maximized.

  As a fourth aspect of the present invention, in the second or third aspect, the motor is orthogonal to the axis of the two bearing rotors corresponding to the two rotation shafts at one or both of the ends of the rotation shaft. You may arrange | position in the outer position in a direction. According to this form, since the motor gives the rotational driving force to both of the two rotating shafts, the driving force of the vacuum pump can be increased.

  As a 5th form of this invention, in a 4th form, a motor may be arrange | positioned at both of the both ends of a rotating shaft. According to this embodiment, the driving force of the vacuum pump can be increased four times as compared with the case where the driving force is applied to only one of the two rotating shafts only on one side of both ends.

  As a sixth aspect of the present invention, in the fourth or fifth aspect, the motor may be a brushless DC motor having a permanent magnet. The permanent magnet may be disposed on the outer surface of each of the two bearing rotors in the circumferential direction of the axis, and may function as a non-contact gear that synchronizes the rotation of the two rotating shafts. According to such a configuration, the permanent magnet of the motor is provided on the bearing rotor and also functions as a non-contact gear. Therefore, compared to the case where the motor and the non-contact gear are arranged side by side in the axial direction, the non-contact gear (permanent) The length of the rotating shaft can be shortened by the length of the magnet.

  As a seventh aspect of the present invention, in the second or third aspect, the motor is provided with one bearing rotor corresponding to one of the two rotating shafts at one of both ends of the rotating shaft. , May be disposed at a position outside the circumferential direction of the axis. The vacuum pump is a non-contact gear having permanent magnets arranged on the outer surface in the radial direction of the axis of two bearing rotors corresponding to the two rotating shafts at the other end of the rotating shaft. You may provide the non-contact gear which synchronizes rotation of a rotating shaft. According to such a configuration, since the non-contact gear is provided in the bearing rotor, compared with the case where the bearing rotor and the non-contact gear are arranged side by side in the direction of the axis, the length of the non-contact gear is equivalent to the length of the rotary shaft. The length can be shortened.

It is explanatory drawing which shows schematic structure of the vacuum pump as 1st Example of this invention. It is the arrow line view which looked at the vacuum pump as 1st Example in the direction of the axis line. It is explanatory drawing which shows schematic structure of the vacuum pump as a comparative example. It is the arrow view which looked at the vacuum pump as a comparative example in the direction of an axis. It is explanatory drawing which shows schematic structure of the vacuum pump as 2nd Example. It is explanatory drawing which shows schematic structure of the vacuum pump as 3rd Example.

  A. First embodiment:

  FIG. 1 shows a schematic configuration of a vacuum pump 20 as a first embodiment of the present invention. 2A to 2C are arrow views of the vacuum pump 20 as viewed in the directions AA, BB, and CC shown in FIG. 1, respectively. In this embodiment, the vacuum pump 20 is a screw type dry vacuum pump having two shafts. As shown in FIG. 1, the vacuum pump 20 includes two rotating shafts 31, 32, magnetic bearings 40, 50, 60, 70, a motor 80, and a non-contact gear 90.

  The rotation shafts 31 and 32 are arranged in parallel to each other, and rotate about the axis lines AL1 and AL2, respectively. The axis AL1 and the axis AL2 are parallel. A screw-type rotor is provided on the outer circumference in the circumferential direction of the rotary shafts 31 and 32.

  The magnetic bearings 40 and 50 support the rotary shaft 31 in a non-contact manner at both ends of the rotary shaft 31 by magnetic levitation. Similarly, the magnetic bearings 60 and 70 support the rotary shaft 32 in a non-contact manner at both ends of the rotary shaft 32.

  The magnetic bearing 40 includes a bearing rotor 41, a first magnetic body 42, a second magnetic body 43, a first electromagnet 44, a second electromagnet 45, and a fixed shaft 46. The bearing rotor 41 has a bottomed cylindrical cup shape. The bearing rotor 41 is joined to the rotary shaft 31 concentrically with the axis AL1. Specifically, the bottom portion of the bearing rotor 41 formed on one side in the direction of the axis AL <b> 1 is joined to the rotating shaft 31. The side opposite to the bottom of the bearing rotor 41, that is, the side opposite to the rotating shaft 31 is open.

  As shown in FIGS. 1 and 2A, a first magnetic body 42 is disposed concentrically with the axis AL1 on the inner surface of the bearing rotor 41 in the circumferential direction. The first magnetic body 42 is formed in an annular shape. As shown in FIG. 1, the second magnetic body 43 is disposed in the direction perpendicular to the axis AL <b> 1 at the bottom of the bearing rotor 41. In the present embodiment, the second magnetic body 43 has a disk shape.

  The fixed shaft 46 is fixedly arranged concentrically with the axis AL1 outside the bearing rotor 41 in the direction of the axis AL1 (on the side opposite to the rotating shaft 31). The rotating shaft 31 side of the fixed shaft 46 has a cylindrical shape and is inserted into the bearing rotor 41.

  On the outer surface in the circumferential direction of the fixed shaft 46, the first electromagnet 44 is disposed in parallel with the axis AL1 along the circumferential direction. The first electromagnets 44 are provided at four locations in the vertical direction and the horizontal direction on a virtual plane orthogonal to the axis AL1. The first magnetic body 42 and the first electromagnet 44 are opposed to each other in the radial direction, and a gap is formed between them.

  A second electromagnet 45 is disposed perpendicular to the axis AL1 on the end surface of the fixed shaft 46 on the rotating shaft 31 side. The second magnetic body 43 and the second electromagnet 45 face the axis AL1 in the direction, and a gap is formed between them.

  Similarly, the magnetic bearing 50 includes a bearing rotor 51, a first magnetic body 52, a second magnetic body 53, a first electromagnet 54, a second electromagnet 55, and a fixed shaft 56. The magnetic bearing 50 has the same configuration as the magnetic bearing 40 and is arranged symmetrically with the magnetic bearing 40 with respect to a virtual plane orthogonal to the axis AL1. The magnetic bearings 60 and 70 have the same configuration as the magnetic bearings 40 and 50. 1 and 2, the components corresponding to each other of the magnetic bearings 40 to 70 are denoted by the same reference numerals in the last digit.

  The bearing rotors 41, 51, 61, 71, the first magnetic bodies 42, 52, 62, 72, and the first electromagnets 44, 54, 64, 74 constitute a radial magnetic bearing. That is, the bearing rotors 41, 51, 61, 71 are attracted in the radial direction by the magnetic attraction force generated in the direction orthogonal to the axis lines AL1, AL2 by the first electromagnets 44, 54, 64, 74, and the bearing rotors 41, 51 , 61, 71 are supported in the radial direction in a non-contact state.

  The bearing rotors 41, 51, 61, 71, the second magnetic bodies 43, 53, 63, 73, and the second electromagnets 45, 55, 65, 75 constitute an axial magnetic bearing. That is, the bearing rotor 41, 51, 61, 71 is attracted outward in the direction of the axis AL1, AL2 by the magnetic attraction force generated in the direction of the axis AL1, AL2 by the second electromagnet 45, 55, 65, 75. The rotary shafts 31, 32 joined to the bearing rotors 41, 51, 61, 71 are supported in the directions of the axes AL1, AL2 in a non-contact state.

  The positions of the rotary shafts 31 and 32 in the directions of the axes AL1 and AL2 and the direction orthogonal thereto are based on the detection result of a non-contact type position sensor (not shown) that measures the displacement of the bearing rotors 41, 51, 61, and 71. The control system (not shown) is suitably maintained by controlling the currents flowing through the first electromagnets 44, 54, 64, 74 and the second electromagnets 45, 55, 65, 75.

  The motor 80 is provided for applying a rotational driving force to the rotary shafts 31 and 32. In this embodiment, the motor 80 is a brushless DC motor. As shown in FIG. 1, the motor 80 includes a stator 81, a first permanent magnet 82, and a second permanent magnet 83. As shown in FIG. 2, the stator 81 is arranged so that the salient poles of the stator core around which the windings are concentrated are surrounded around the bearing rotor 41 and the bearing rotor 61. The first permanent magnet 82 is disposed on the outer surface of the bearing rotor 41 in the circumferential direction along the circumferential direction. The second permanent magnet 83 is disposed on the outer surface of the bearing rotor 61 in the circumferential direction along the circumferential direction.

  The bearing rotors 41 and 61 having the first permanent magnet 82 or the second permanent magnet 83 function as a motor rotor, and rotate in opposite directions by energizing the windings of the stator 81. Since the bearing rotors 41 and 61 are joined to the rotating shafts 31 and 32, when the bearing rotors 41 and 61 rotate, the rotating shafts 31 and 32 also rotate. In the present embodiment, the motor 80 is disposed outside the bearing rotor 41 and the bearing rotor 61 in a direction orthogonal to the axes AL1 and AL2. For this reason, the motor 80 gives a rotational driving force to both the rotating shafts 31 and 32. With this configuration, it is possible to improve the rotational driving force by a factor of two compared to a configuration in which the rotational driving force is applied to only one of the rotating shafts 31 and 32 and the other is transmitted through the non-contact gear. . As a result, the vacuum pump 20 can be reduced in size.

  In this embodiment, the length L1 of the motor 80 in the direction of the axes AL1 and AL2 is longer than the length L2 of the magnetic bearings 40 and 60 in the direction of the axes AL1 and AL2. Here, the length L <b> 2 is the length of the arrangement range of the first magnetic body 42, the second magnetic body 43, and the first electromagnet 44. And the magnetic bearings 40 and 60 are arrange | positioned in the position which overlaps with the motor 80 in the direction of axis line AL1, AL2 over the whole length of the direction of axis line AL1, AL2 of magnetic bearing 40,60.

  The non-contact gear 90 is configured by the first permanent magnet 82 and the second permanent magnet 83 described above. The non-contact gear 90 forms a magnetic coupling with different magnetic pole surfaces, and synchronizes the rotation of the rotary shafts 31 and 32. That is, in the present embodiment, the first permanent magnet 82 and the second permanent magnet 83 are used (shared) as the permanent magnet of the magnetic coupling.

  In the vacuum pump 20 described above, the rotation shafts 31 and 32 rotate in opposite directions by driving the motor 80. As a result, the pair of rotors provided on the rotary shafts 31 and 32 rotate in opposite directions without contact while maintaining a slight gap between the inner surface of the rotor chamber and the pair of rotors. As the pair of rotors rotate, the gas sucked from the intake port (not shown) is confined between the inner surface of the rotor chamber and the pair of rotors, and transferred to the exhaust passage (not shown).

  In order to clarify the effect of the vacuum pump 20 described above, a configuration of a conventional vacuum pump 120 as a comparative example will be described. FIG. 3 shows a schematic configuration of the vacuum pump 120. 4A to 4D are arrow views of the vacuum pump 120 as viewed in the directions AA, BB, CC, and DD shown in FIG. 3, respectively. In FIG. 3 and FIG. 4, each component of the vacuum pump 120 is assigned a reference numeral having the last two digits of the reference numerals assigned to the corresponding components of the vacuum pump 20 as the first embodiment.

  In the vacuum pump 120, the rotary shaft 131 is supported by magnetic bearings 140 and 150 at both ends thereof. The magnetic bearing 140 includes a cylindrical bearing rotor 147 joined to the rotating shaft 131, and a first electromagnet 144 disposed around the bearing rotor 147. The bearing rotor 147 and the first electromagnet 144 constitute a radial magnetic bearing. The end of the bearing rotor 147 on the outer side (opposite to the rotating shaft 131) in the direction of the axis AL1 is connected to the motor 180.

  Similar to the magnetic bearing 140, the magnetic bearing 150 includes a bearing rotor 157 and a first electromagnet 154 that constitute a radial magnetic bearing. The end of the bearing rotor 157 on the outer side (opposite to the rotating shaft 131) in the direction of the axis AL1 is connected to a disk-shaped magnetic body 158. Second electromagnets 155 are provided on both sides of the magnetic body 158 in the direction of the axis AL1. The second electromagnet 155 and the magnetic body 158 constitute a thrust magnetic bearing.

  Since the bearing rotors 147 and 157 and the magnetic body 158 rotate together with the rotating shaft 131, they can be regarded as rotating shafts. The magnetic bearings 160 and 170 have the same configuration as the magnetic bearings 140 and 150. In FIG. 3, the non-contact gear is not shown.

  According to the vacuum pump 20 of the present embodiment described above, the axial bearing is disposed inside the cylindrical cup-shaped bearing rotors 41, 51, 61, 71, so that it is magnetic compared to the vacuum pump 120 as a comparative example. The length of the rotating shaft can be shortened by the length of the bodies 158 and 178 in the direction of the axis lines AL1 and AL2. As a result, the contact between the two rotating shafts when the vacuum pump is rotated at a high speed can be suppressed, and the rotation speed can be increased by that much.

  Further, according to the vacuum pump 20, the magnetic bearings 40, 60 overlap the motor 80 in the directions of the axes AL1, AL2 over the entire length L2 of the magnetic bearings 40, 60 in the directions of the axes AL1, AL2. Placed in position. For this reason, compared with the vacuum pump 120, the length of a rotating shaft can be shortened by the overlap.

  Further, according to the vacuum pump 20, the first permanent magnet 82 and the second permanent magnet 83 of the motor 80 also function as the non-contact gear 90. For this reason, compared with the case where the motor 80 and the non-contact gear 90 are arranged side by side in the directions of the axes AL1 and AL2, the length of the rotating shaft can be shortened by the length of the non-contact gear 90.

With these configurations, the vacuum pump 20 can make the length of the rotating shaft equal to or less than that of the conventional bearing system. Therefore, even if the vacuum pump 20 is rotated at a high speed, the possibility that the two rotating shafts come into contact with each other can be remarkably suppressed, which is extremely effective when the vacuum pump 20 is downsized.

B. Second embodiment:
FIG. 5 shows a schematic configuration of a vacuum pump 220 as a second embodiment. In FIG. 5, each component of the vacuum pump 220 is assigned a reference numeral having the last two digits of the reference numerals assigned to the corresponding components of the vacuum pump 20 as the first embodiment. In the following, only the differences of the vacuum pump 220 from the first embodiment will be described.

  In the vacuum pump 220, the motor 280 is disposed outside the bearing rotor 261 in a direction orthogonal to the axis AL2. That is, the motor 280 is provided at a position that surrounds the bearing rotor 261 in the circumferential direction and does not surround the bearing rotor 241 in the circumferential direction. With this arrangement, the motor 280 applies driving force only to the rotating shaft 232 of the rotating shafts 231 and 232.

  With this arrangement, the bearing rotor 241 is not provided with the first permanent magnet 82 of the first embodiment. On the other hand, the vacuum pump 220 includes a non-contact gear 290 at the other end opposite to one end where the motor 280 is provided, at both ends of the rotating shaft 231. The non-contact gear 290 includes permanent magnets 291 and 292. The permanent magnet 291 is disposed on the outer surface of the bearing rotor 251 in the circumferential direction along the circumferential direction. The permanent magnet 292 is disposed on the outer circumferential surface of the bearing rotor 271 along the circumferential direction. The non-contact gear 290 also has a function of transmitting the rotational driving force of the rotating shaft 232 generated by driving the motor 280 to the rotating shaft 231.

  According to such a vacuum pump 220, compared to the case where the bearing rotors 251 and 272 and the non-contact gear 290 are arranged side by side in the directions of the axis lines AL1 and AL2, the rotation shaft has a length corresponding to the length of the non-contact gear 290. The length can be shortened.

C. Third embodiment:
FIG. 6 shows a schematic configuration of a vacuum pump 320 as a third embodiment. In FIG. 6, each component of the vacuum pump 320 is assigned a reference numeral having the last two digits of the reference numeral assigned to each component of the vacuum pump 20 according to the first embodiment. Hereinafter, only the points of the vacuum pump 320 that are different from the first embodiment will be described.

  The vacuum pump 320 includes two motors 380a and 380b. The motor 380a is disposed outside the bearing rotors 341 and 361 in a direction orthogonal to the axes AL1 and AL2. Similarly, the motor 380b is disposed outside the bearing rotors 351 and 371 in the direction orthogonal to the axes AL1 and AL2. With this configuration, the first permanent magnet 382b is disposed on the outer circumferential surface of the bearing rotor 351 along the circumferential direction. Similarly, the 2nd permanent magnet 383b is arrange | positioned along the circumferential direction on the outer surface of the circumferential direction of the bearing rotor 371.

  The first permanent magnet 382a and the second permanent magnet 383a of the motor 380a function as a non-contact gear 390a, and the first permanent magnet 382b and the second permanent magnet 383b of the motor 380b function as a non-contact gear 390b. To do.

  According to the vacuum pump 320, the driving force of the vacuum pump can be increased four times as compared with the second embodiment. Note that only one of the motors 380a and 380b may be arranged to apply a driving force to both of the rotating shafts 331 and 332 and the other to provide a driving force to only one of the rotating shafts 331 and 332.

D. Variations:
D-1. Modification 1:
In the first embodiment described above, the case where the length L1 in the direction of the axes AL1 and AL2 of the motor 80 is greater than or equal to the length L2 in the direction of the axes AL1 and AL2 of the magnetic bearings 40 and 60 is illustrated. However, when the length L1 in the direction of the axes AL1 and AL2 of the motor 80 is shorter than the length L2 in the direction of the axes AL1 and AL2 of the magnetic bearings 40 and 60, the motor 80 is connected to the axes AL1 and AL1 of the motor 80. You may arrange | position in the position which overlaps with the magnetic bearings 40 and 60 in the direction of axial line AL1, AL2 over the whole length L1 of the direction of AL2.

  The motor 80 is located outside the magnetic bearings 40 and 60 in the direction orthogonal to the axes AL1 and AL2, and only a part of the motor 80 and the magnetic bearings 40 and 60 are in the directions of the axes AL1 and AL2. You may arrange | position in the overlapping position. For example, when the length L1 in the direction of the axes AL1 and AL2 of the motor 80 is longer than the length L2 in the direction of the axes AL1 and AL2 of the magnetic bearings 40 and 60, the magnetic bearings 40 and 60 are connected to the axes AL1 and AL2. In this direction, it protrudes outward from the motor 80, and only a partial region of the magnetic bearings 40, 60 may overlap with the motor 80 in the directions of the axes AL1, AL2. Even if it does in this way, the effect which can shorten a rotating shaft is produced to some extent. This point can be similarly applied to the second or third embodiment.

D-2. Modification 2:
In the first embodiment described above, the motor 80 may be an AC motor. In this case, the first permanent magnet 82 and the second permanent magnet 83 are not necessary. In this case, the non-contact gear 90 made of a permanent magnet provided on the bearing rotor can be provided on the opposite side of the both ends of the rotating shafts 31 and 32 from the side where the motor 80 is provided. These points can be similarly applied to the second embodiment. In addition, when arrange | positioning a non-contact gear and a bearing rotor side by side in the direction of an axis line, it is applicable also to 3rd Example.

D-3. Modification 3:
In the second embodiment described above, a non-lubricated contact gear may be used instead of the non-contact gear 290. Such a gear is described in, for example, Japanese Patent Laid-Open No. 2000-329084. In this gear, a magnetic coupling is formed by different magnetic pole surfaces, thereby synchronizing two rotating shafts, minimizing torque transmission of the contact gear, and eliminating lubrication.

D-4. Modification 4:
The above-described embodiment is not limited to a screw-type dry vacuum pump, and can be applied to various volume transfer vacuum pumps having two shafts, for example, a roots-type dry vacuum pump.

  The embodiments of the present invention have been described above based on some examples. However, the above-described embodiments of the present invention are for facilitating the understanding of the present invention and limit the present invention. It is not a thing. The present invention can be changed and improved without departing from the gist thereof, and the present invention includes the equivalents thereof. Moreover, in the range which can solve at least one part of the subject mentioned above, or the range which exhibits at least one part of an effect, the combination of each component described in the claim and the specification, or omission is possible. .

20, 220, 320 ... vacuum pumps 31, 32, 231, 232, 331, 332 ... rotating shafts 40, 50, 60, 70, 240, 250, 260, 270, 340, 350, 360, 370 ... magnetic bearings 41, 51,61,71,241,251,261,271,341,351,36
DESCRIPTION OF SYMBOLS 1,371 ... Bearing rotor 42,52,62,72,242,252,262,272,342,352,362,372 ... 1st magnetic body 43,53,63,73,243,253,263,273 , 343, 353, 363, 373 ... second magnetic bodies 44, 54, 64, 74, 244, 254, 264, 274, 344, 354, 364, 374 ... first electromagnets 45, 55, 65, 75, 245, 255, 265, 275, 345, 355, 365, 375, ... second electromagnets 46, 56, 66, 76, 246, 256, 266, 276, 346, 356, 366, 376, ... fixed shaft 80, 280, 380a, 380b ... motor 81 ... stator 82, 382a, 382b ... first permanent magnet 83, 283, 383a, 383b ... second permanent magnet 90,290,390a, 390b ... non-contact gears 291 and 292 ... permanent magnet AL1 ... axis AL2 ... axis

Claims (7)

A vacuum pump,
Two rotation axes that are arranged in parallel and rotate synchronously around two axes,
A magnetic bearing for supporting the rotary shaft at both ends of each of the two rotary shafts;
The magnetic bearing is
A bearing rotor having a cylindrical cup shape, including a magnetic material, and rotating together with the rotating shaft;
A first electromagnet disposed parallel to the axis within the bearing rotor;
A vacuum pump comprising: a second electromagnet disposed perpendicular to the axis inside the bearing rotor, wherein the second electromagnet generates a magnetic attractive force in the direction of the axis at both ends of the rotating shaft. . The vacuum pump according to claim 1,
A motor for applying a rotational driving force to at least one of the two rotational shafts;
The said motor is a position outside the said bearing rotor in the direction orthogonal to the said axis line, Comprising: At least one part of the said motor and the said magnetic bearing is arrange | positioned in the position which overlaps in the direction of the said axis line. The vacuum pump according to claim 2,
When the length in the direction of the axis of the first device that is one of the motor and the magnetic bearing is equal to or longer than the length in the direction of the axis of the second device that is the other device,
The said 2nd apparatus is arrange | positioned in the position which overlaps with the said 1st apparatus over the whole length of the direction of the said axis of the said 2nd apparatus in the direction of the said axis line. A vacuum pump according to claim 2 or claim 3,
The said motor is a vacuum pump arrange | positioned in the one or both of the said both ends of the said rotating shaft in the outer position in the direction orthogonal to the said axis line of the two said bearing rotors corresponding to the said two rotating shafts. The vacuum pump according to claim 4,
The said motor is a vacuum pump arrange | positioned at both of the said both ends of the said rotating shaft. A vacuum pump according to claim 4 or claim 5, wherein
The motor is a brushless DC motor having a permanent magnet,
The permanent magnet is disposed on an outer surface of each of the two bearing rotors in the circumferential direction of the axis, and functions as a non-contact gear that synchronizes the rotation of the two rotating shafts. A vacuum pump according to claim 2 or claim 3,
The motor is disposed at one of the two ends of the rotating shaft at a position radially outside the axial line of the one bearing rotor corresponding to the rotating shaft of one of the two rotating shafts. And
The vacuum pump has a non-contact gear having permanent magnets arranged on the outer circumference in the circumferential direction of the axis of the two bearing rotors corresponding to the two rotating shafts at the other of the both ends of the rotating shaft. A vacuum pump comprising a non-contact gear that synchronizes the rotation of the two rotating shafts.

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