JP2006296061A - motor - Google Patents

Abstract

【Task】
Provided is a motor that can be easily maintained while being used in a vacuum atmosphere.
[Solution]
Since the bolts 41 and 42 arranged on the vacuum atmosphere side are subjected to predetermined surface treatment, adhesion of the bolts 41 and 42 attached in the vacuum atmosphere can be suppressed, and maintenance can be easily performed. The operating rate of the entire system including the damotor can be improved.
[Selection] Figure 1

Description

  The present invention relates to a motor suitable for use in a vacuum, for example.

  For example, in a semiconductor manufacturing apparatus or the like, a workpiece is processed in an ultra-high vacuum atmosphere in a vacuum chamber in order to eliminate impurities as much as possible. As an actuator used in that case, for example, in a drive motor of a workpiece positioning device, a lubricant containing a volatile component such as general grease cannot be used for a drive shaft bearing. Lubrication is enhanced by plating soft metals such as gold and silver on the inner and outer rings of the bearing. In addition, there is a fact that a stable material with excellent heat resistance and low emission gas is selected for the coil insulating material of the drive motor, the wiring coating material, and the adhesive of the laminated magnetic pole.

  In particular, in recent years, the degree of integration of semiconductors has increased, and at the same time, higher density has been promoted by reducing the pattern width of the IC. In order to manufacture a wafer that can cope with this miniaturization, a high degree of uniformity in wafer quality is required. In order to meet the demand, it is important to further reduce the impurity gas concentration in the low-pressure gas processing chamber of the wafer. Further, in order to perform microfabrication as required, an extremely high precision positioning device is required. From the above viewpoint, the following problems are pointed out when the conventional actuator is examined.

  That is, in the case of a drive motor used in a vacuum chamber equipped with an ultra-vacuum atmosphere, even if a stable material with excellent heat resistance and low emission gas is selected for the coil insulation material or wiring coating of the drive motor, As long as it is an organic insulating material, it is microscopically porous and has numerous holes on its surface. Once this is exposed to the atmosphere, gas, water molecules, etc. are taken in and occluded in the holes on the surface. A long time is required for degassing to remove these occluded impure molecules by vacuum evacuation, and a reduction in production efficiency is unavoidable. Furthermore, since heat cannot be released due to air convection in a vacuum, when the coil temperature rises locally, the resistance of that portion increases, heat generation is accelerated, and the coil insulation film is burned out. Easy to invite. On the other hand, while using an inorganic material for the coil insulating material, it is conceivable to reduce adsorbed impure molecules by using a stainless steel sheath wire for the wiring. However, in that case, not only the cost becomes very high, but also the ratio of conductors such as copper in the coil winding space decreases, resulting in an increase in electrical resistance, resulting in a decrease in motor capacity. There is.

In order to solve such a problem, Patent Document 1 discloses a motor in which a stator is disposed inside a vacuum sealing body, an output member is disposed outside thereof, and a frog leg arm is driven using an output member, that is, a rotor. ing. According to the motor of Patent Document 1, coil insulation materials and wiring coatings attached to the stator are arranged inside the vacuum sealing body maintained at atmospheric pressure, and therefore occlusion when they are arranged in a vacuum chamber. It is possible to avoid the problem of emission of impure molecules and the problem of heat generation.
JP 2000-69741 A

  By the way, in the motor of Patent Document 1, a bearing for supporting a rotor or the like exists in a vacuum atmosphere. However, when grease is used as the lubricant, lubrication occurs due to evaporation of grease oil or scattering of the grease itself. There may be inconveniences such as degradation of performance and contamination of the usage environment. Therefore, lubricity is often imparted by coating a soft metal such as gold, silver or lead, or a solid lubricant such as carbon or molybdenum disulfide into a film instead of using grease.

  However, if solid lubrication or the like is used for the bearing, the life is shortened as compared with a bearing using a general lubricant, and therefore maintenance is required to be periodically disassembled and replaced. However, since the bolts for fixing the rotor and the bearing are also in a vacuum atmosphere, adhesion due to contact of metals with a strong surface pressure is likely to occur, and it may be difficult to loosen them. If it takes time to loosen the bolts, the maintenance time becomes longer, and the operating rate of the entire system using the motor and therefore the motor is lowered.

  The present invention has been made in view of the problems of the prior art, and an object thereof is to provide a motor that is easily maintained while being used in a vacuum atmosphere.

  The motor of the present invention is characterized in that in a motor used in a vacuum atmosphere, a predetermined surface treatment is applied to at least a bolt disposed on the vacuum atmosphere side.

  According to the present invention, since a predetermined surface treatment is applied to at least the bolt arranged on the vacuum atmosphere side, adhesion of the bolt attached in the vacuum atmosphere can be suppressed, and maintenance can be easily performed. The operating rate of the entire system including this motor can be improved.

  Furthermore, if the predetermined surface treatment is at least one of heat treatment, plating, and coating, adhesion of the bolt can be effectively suppressed.

  Furthermore, if the predetermined surface treatment is coated with a diamond-like carbon film, adhesion of the bolts can be more effectively suppressed.

  Furthermore, the bolt is preferably a bolt for fastening a bearing or rotating body used in a vacuum atmosphere.

  Further, the motor is a direct drive motor that directly drives the rotor without using a reduction gear or the like, and a housing, a partition extending from the housing and separating the atmosphere side and the vacuum atmosphere side, and the partition An outer rotor disposed on the vacuum atmosphere side, a stator and an inner rotor disposed on the atmosphere side with respect to the partition wall, and a detector that detects a rotation speed of the inner rotor, When the outer rotor and the inner rotor are driven at the same time, by placing the detector on the atmosphere side from the partition wall, it is possible to prevent the impure molecules of the wiring coating from contaminating the atmosphere outside the atmosphere from the partition wall, and The stator detects the rotation angle of the inner rotor by the detector by driving the outer rotor and the inner rotor at the same time. It can be determined rotational angle of the outer rotor accurately.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of a frog-leg-arm type transfer device using a motor according to the present embodiment. In FIG. 1, two motors D1 and D2 are connected in series. A first arm A1 is coupled to the rotor of the lower motor D1, and a first link L1 is pivotably coupled to the tip of the first arm A1. On the other hand, the second arm A2 is connected to the rotor of the upper motor D2, and the second link L2 is pivotally connected to the tip of the second arm A2. The links L1 and L2 are pivotally connected to a table T on which the wafer W is placed.

  As is clear from FIG. 1, if the rotors of the motors D1 and D2 rotate in the same direction, the table T also rotates in the same direction, and if the rotor rotates in the opposite direction, the table T moves to the motors D1 and D2. It comes to approach or separate. Therefore, if the motors D1 and D2 are rotated at an arbitrary angle, the wafer W can be transferred to an arbitrary two-dimensional position within a range where the table T can reach.

  Thus, for example, in a wafer transfer arm disposed in a vacuum chamber in a semiconductor manufacturing apparatus, for example, an apparatus having a plurality of arms such as a scalar type or a frog-leg type shown in the figure, a plurality of rotary motors are required. . In a vacuum environment, it is necessary to reduce the surface area of contact with the outside as much as possible, and at the same time to reduce the number of mounting holes for a motor or the like as much as possible in order to effectively use the space. In addition, in order to transport the wafer W horizontally and with minimal vibration, it is necessary to firmly hold the moment acting on the tip of the arm with the rotor support. Therefore, a plurality of motors D1 and D2 are connected coaxially at the housing part, and the connecting part is tightly joined with a seal (tightly joined by welding, O-ring, metal gasket, etc.), and the space where the motor rotor is disposed It is also necessary to separate the housing from the external space.

  Further, in order to convey the wafer W horizontally and with less vibration, it is necessary to firmly hold the moment acting on the tips of the arms A1 and A2 by the rotor support portion. Furthermore, when driving multiple axes in a vacuum environment, if the current rotation position of the arm is not recognized when the power is turned on, the arm A1, A2, etc. are hit against the wall of the vacuum chamber or the shutter of the vacuum chamber. There is a possibility. A motor capable of meeting such a request will be described.

  FIG. 2 is a view of the configuration of FIG. 1 taken along the line II-II and viewed in the direction of the arrow. FIG. 3 is a view of the configuration of FIG. 2 taken along line III-III and viewed in the direction of the arrow. The internal structure of the motor will be described in detail with reference to FIGS. Since the motors D1 and D2 have the same basic configuration, only the motor D1 will be described, and the description of the configuration of the motor D2 will be omitted by attaching the same reference numerals.

  The hollow cylindrical main body 10 with the flange 10a installed on the surface plate G has a small disk 11 connected to the upper end thereof by a bolt. A large disk 12 is fixed to the upper surface of the small disk 11 by a bolt (not shown). The center of the main body 10 can be used for passing wiring to the stator. The main body 10, the small disk 11, and the large disk 12 constitute a housing.

  On the flange 10 a of the main body 10, a cylindrical partition wall 13 made of stainless steel (SUS304 or the like) that is a non-magnetic material is attached coaxially to the main body 10. The upper part of the partition wall 13 is thin, and the upper end is bent inward in the radial direction, and is attached so as to be sandwiched by the small disk 11 by the disk 12. Incidentally, an O-ring OR is arranged between the members of the motor D1, as shown in the figure. Therefore, an internal space surrounded by the flange 10a of the main body 10, the partition wall 13, and the small disk 11 is from the outside. It is airtight. In addition, the partition 13 does not necessarily need to be a nonmagnetic material. Further, instead of using the O-ring OR, the members may be hermetically sealed by electron beam welding or laser beam welding.

  An inner ring of a four-point contact ball bearing 14 used in vacuum is fitted to the lower outer periphery of the partition wall 13 and is attached to the partition wall 13 by an inner ring holder 15 fixed to the partition wall 13 with bolts 41. On the other hand, the outer ring of the bearing 14 is attached to the outer rotor 16 by an outer holder 17 that fits to the inner periphery of the outer rotor 16 and is fixed to the outer rotor 16 with bolts 42. That is, the outer rotor 16 is rotatably supported with respect to the partition wall 13. The bearing 14 is a four-point contact ball bearing in which a soft metal such as gold or silver is plated on the inner ring and the outer ring so as to prevent outgassing even in a vacuum. Can receive a moment in the direction in which the outer rotor 16 tilts, but is not limited to a four-point contact type, and a cross roller, a cross ball, a cross taper bearing can also be used, and may be used in a preload state. Fluorine-based coating treatment (DFO) may be performed to improve lubricity.

  In the present embodiment, since no grease is used for the four-point contact ball bearings 14 arranged in a vacuum atmosphere, outgassing can be suppressed, but the durability is reduced by that amount, so periodic maintenance is performed. Is required. On the other hand, a bolt 41 for fixing the inner ring of the four-point contact ball bearing 14 to the partition wall 13 and a bolt 42 for fixing the outer ring of the four-point contact ball bearing 14 to the outer ring rotor 16 are used. In order to facilitate maintenance, it is necessary to suppress the adhesion. Therefore, the bolts 41 and 42 are subjected to a predetermined surface treatment.

  Examples of the predetermined surface treatment include heat treatment, plating, and coating. Examples of the heat treatment of the bolt include normal quenching / tempering treatment, nitriding treatment, carburizing treatment, and carbonitriding treatment. Examples of the plating include electroless nickel plating and hard chrome plating. Furthermore, coatings include films formed by PVD and CVD, including Ti-based hard films (TiN, TiCN, TiC, TiAIN), CrN, diamond, diamond-like carbon (DLC), etc., especially diamond-like carbon. Also preferred are coatings.

  An outer rotor magnet 18 is attached to the inner peripheral surface of the outer rotor 16. The outer rotor magnet 18 is composed of 24 poles and 12 poles of N poles and S poles are alternately made of magnetic metal, and are assembled to the back yoke 19. The back yoke 19 may be magnetic stainless steel or iron plated with nickel. In the present embodiment, the outer rotor magnet 18 is a neodymium iron boron magnet nickel-plated. Further, the outer rotor magnet 18 is fastened to the outer rotor 16 with a nonmagnetic metal wedge. Therefore, no resin such as an adhesive is disposed, and even when the motor D1 is disposed in a vacuum, the released gas of the occluded impurity molecules can be extremely reduced. A magnetic shield plate 30 is attached to the outer rotor 16 so as to cover the upper portion of the outer rotor magnet 18.

  A stator 29 is arranged on the inner side in the radial direction of the partition wall 13 so as to face the inner peripheral surface of the outer rotor 16. The stator 29 is attached to the flange 10a of the main body 10 by the stator holder 20, and as shown in FIG. 3, 12 coils of each phase are arranged in a cylindrical shape in the order of U phase, V phase, and W phase. Therefore, a total of 36 coils are included. This coil is molded by a molding material and integrated. Since the stator 29 is thus arranged inside the partition wall 13, forced cooling such as water cooling or air cooling can be performed against coil heat generation or the like.

  The inner rotor 21 is arranged on the inner side in the radial direction of the stator 29. The inner rotor 21 is rotatably supported by ball bearings 23 with respect to a resolver holder 22 that is bolted to the outer peripheral surface of the main body 10. An inner rotor magnet 24 is attached to the outer peripheral surface of the inner rotor 21 via a back yoke 25. Similarly to the outer rotor magnet 18, the inner rotor magnet 24 has a 24-pole configuration, and 12 N-pole and S-pole magnets are alternately made of magnetic metal and are assembled to the back yoke 25. Therefore, the inner rotor 21 is rotationally driven by the stator 29 in synchronization with the outer rotor 16.

  A detection rotor 26 for a detector for measuring a rotation angle is assembled on the inner circumference of the inner rotor 21, and resolvers 27 and 28 are attached to the outer circumference of the resolver holder 22 so as to face the rotor. In the embodiment, the high-resolution incremental resolver 27 and the absolute resolver 28 capable of detecting the position of the rotor at one rotation are arranged in two layers. Therefore, even when the power is turned on, the rotation angle of the detection rotor 26 can be known, no return to origin is required, and the electrical phase angle of the magnet with respect to the coil can be known. This is possible without using a pole detection sensor.

  In the high-resolution variable reluctance resolver used in the present embodiment, the detection rotor 26 has a plurality of slot teeth having a constant pitch, and the outer peripheral surfaces of the magnetic poles of the stators of the resolvers 27 and 28 are Teeth whose phases are shifted with respect to the detection rotor 26 by the magnetic poles are provided in parallel with the rotation axis, and coils are wound around the magnetic poles. When the detection rotor 26 rotates integrally with the inner rotor 21, the reluctance between the resolvers 27 and 28 and the magnetic poles of the stator changes, and the fundamental wave component of the change in reluctance becomes n periods in one rotation of the detection rotor 26. The reluctance change is detected, digitized by the resolver control circuit shown in FIG. 4 and used as a position signal to detect the rotation angle (or rotation speed) of the detection rotor 26, that is, the inner rotor 21. It has become. The detection rotor 26 and the resolvers 27 and 28 constitute a detector.

  In the present embodiment, the inner rotor 21 is rotationally driven in synchronization with the outer rotor 16 by the stator 29. Therefore, if the rotation angle of the inner rotor 21 can be detected, the rotation of the outer rotor 16 is immediately performed. The angle can be obtained, whereby the drive control of the outer rotor 16 can be performed with high accuracy.

  FIG. 5 is a block diagram showing a drive circuit of the motor D1. When a motor rotation command is input from an external computer, the motor control circuit DMC outputs a drive signal from the CPU to the three-phase amplifier (AMP), and a drive current is supplied from the three-phase amplifier (AMP) to the motor D1. The Thereby, the outer rotor 16 of the motor D1 rotates to move the arm A1. When the outer rotor 16 rotates, resolver signals are output from the resolvers 27 and 28 whose rotation angles have been detected as described above. Therefore, the CPU that has been input after digital conversion by the resolver digital converter (RDC) It is determined whether or not the rotor 16 has reached the command position. If the command position is reached, the rotation of the outer rotor 16 is stopped by stopping the drive signal to the three-phase amplifier (AMP). This enables servo control of the outer rotor 16.

In the present embodiment, since the absolute resolver 28 is used, the current flowing through the three-phase stator coil can be controlled in accordance with the electrical angle of the detection rotor 26 and the torque command. When a current is passed through the three-phase coils (U-phase, V-phase, W-phase) of the motor D1, the structure is a coreless motor. Therefore, according to Fleming's left-hand rule, the outer rotor 16 and the inner rotor 21 are almost the same. Torque can be generated. Originally, if the inner rotor 21 and the outer rotor 16 do not synchronize, each is supported by a rotatable bearing. T _O : Torque generated on the outer rotor 16 I _O : Inertia including the load on the outer rotor 16 side α _O : Acceleration of outer rotor 16 T _I : Torque generated on inner rotor 21 I _I : Inertia of inner rotor 21 α _I : Acceleration of inner rotor 21 Since arm A1 is attached to outer rotor 16, Io: Since the inertia including the load on the outer rotor 16 side is large,
T _O = I _O × α _O
T _I = I _I × α _I
Try to rotate at different accelerations.

  However, since the outer rotor 16 and the inner rotor 21 rotate in synchronization, a predetermined torque is generated by the displacement of the rotation angle. Therefore, torque is transmitted from the inner rotor 21 to the outer rotor 16 by the minute angle phase of the inner rotor 21 having no loading load with respect to the outer rotor 16 in the torque generation direction. As a result, the inner rotor 21 and the outer rotor 16 are transmitted. And the torque is transmitted so that the accelerations are the same, and the torque generated by the coil is generated according to the inertia.

  In the present embodiment described above, since the motor D1 supports the moment force by the multipoint contact bearing 14, the rigidity is high, and the wafer W can be transported horizontally and straight even when the arm A1 is extended. Further, since the inner ring of the bearing 14 is assembled to the thick member of the partition wall 13, the acting force hardly acts on the partition wall 13 and is directly applied to the main body 10, so that the risk of the partition wall 13 being broken is extremely small. can do.

  Also, when driving multiple axes in a vacuum environment, if the current rotation position of the arm A1 is not recognized when the power is turned on, the arm A1 or the like may hit the wall of the vacuum chamber or the shutter of the vacuum chamber. However, in the present embodiment, a variable reluctance resolver comprising an absolute resolver 28 that detects the absolute position of one rotation of the rotating shaft and an incremental resolver 27 that detects a rotational position with finer resolution is employed. The rotational position of the outer rotor 16, that is, the arm A1, can be controlled with high accuracy.

  In particular, since the bolts 41 and 42 arranged on the vacuum atmosphere side are subjected to a predetermined surface treatment, adhesion of the bolts 41 and 42 attached in the vacuum atmosphere can be suppressed, and maintenance can be easily performed. The operating rate of the entire system including this motor can be improved. For example, a predetermined surface treatment may be performed on a bolt for fixing the magnetic shield plate 30.

  Here, a resolver is employed for detecting the rotation of the inner rotor 21. However, since the detector can be disposed on the atmosphere side inside the partition wall 13, a servo motor generally used for high-accuracy positioning is driven with high accuracy and smoothness. For example, an optical encoder that is employed as a position detecting means, a magnetic encoder using a magnetoresistive element, or the like can be used.

  FIG. 6 is a diagram illustrating a modification of the present embodiment. In the modification shown in FIG. 6, two sets of motors D1 and D2 (a total of four) are arranged in series. However, the individual motors are the same as those shown in FIG. The same reference numerals are given and description thereof is omitted.

  In the motor of this embodiment, since the inner rotor is arranged on the radially inner side of the stator, the axial dimension can be made small (thin), so that the conveyor device is configured as four in series as shown in FIG. However, it is possible to provide a compact configuration in the height direction. In addition, since the structure is thin, the rigidity is increased and the risk of resonance or the like can be avoided, which is advantageous for multi-axis use, and the difference in control constant between the outer rotors can be reduced. Furthermore, by stacking and using motors having the same shape, only the motors need to be replaced in the event of a failure, and the maintenance is excellent and the inventory of replacement parts can be minimized.

  FIG. 7 is a cross-sectional view similar to FIG. 2 of a motor according to a second embodiment that can be used in the transport apparatus shown in FIG. Since the motors D1 and D2 have the same basic configuration, only the motor D1 will be described, and the description of the configuration of the motor D2 will be omitted by attaching the same reference numerals.

  In FIG. 7, a hollow cylindrical main body 110 in which a flange 110a is installed on a surface plate G has a small disk 111 connected to its upper end by a bolt. A large circular plate 112 is fixed to the outer peripheral side of the upper surface of the small circular plate 111 with a bolt (not shown). The center of the main body 110 can be used to pass wiring to the stator. The main body 110, the small disk 111, and the large disk 112 constitute a housing.

  A cylindrical partition 113 made of stainless steel (such as SUS316L), which is a non-magnetic material, is coaxially attached to the main body 110 by press-fitting the lower end into a cylindrical mounting portion 110b formed on the flange 110a of the main body 110. ing. The upper part of the partition wall 113 is thin, and the upper end is bent inward in the radial direction, and is attached to the small disk 111 by the disk 112 so as to be fastened together. Incidentally, an O-ring OR is arranged between the members of the motor D1 as shown in the figure, and therefore the internal space surrounded by the flange 110a of the main body 110, the partition wall 113, and the small circular plate 111 is from the outside. It is airtight. The partition wall 113 is not necessarily made of a nonmagnetic material. Further, instead of using the O-ring OR, the members may be hermetically sealed by electron beam welding or laser beam welding.

  An inner ring of a four-point contact ball bearing 114 used in vacuum is fitted to the lower outer periphery of the partition wall 113 and attached to the partition wall 113 by an inner ring holder 115 fixed to the partition wall 113 with bolts 141. On the other hand, the outer ring of the bearing 114 is attached to the outer rotor 116 by an outer holder 117 that fits to the inner periphery of the outer rotor 116 and is fixed to the outer rotor 116 with bolts 142. That is, the outer rotor 116 is rotatably supported with respect to the partition wall 113. The bearing 114 is a four-point contact ball bearing in which a soft metal such as gold or silver is plated on the inner ring and the outer ring so as to prevent outgassing even in a vacuum. Can receive a moment in the direction in which the outer rotor 116 tilts, but is not limited to a four-point contact type, and a cross roller, a cross ball, a cross taper bearing can also be used, and may be used in a preload state. Fluorine-based coating treatment (DFO) may be performed to improve lubricity.

  Also in this embodiment, since no grease is used for the four-point contact ball bearing 114 arranged in a vacuum atmosphere, outgassing can be suppressed, but the durability is reduced by that amount, so periodic maintenance is performed. Is required. On the other hand, a bolt 141 for fixing the inner ring of the four-point contact ball bearing 114 to the partition wall 113 and a bolt 142 for fixing the outer ring of the four-point contact ball bearing 114 to the outer ring rotor 116 are used. In order to facilitate maintenance, it is necessary to suppress the adhesion. Therefore, the predetermined surface treatment described above is performed on the bolts 141 and 142. That is, since the bolts 141 and 142 arranged on the vacuum atmosphere side are subjected to a predetermined surface treatment, adhesion of the bolts 141 and 142 attached in the vacuum atmosphere can be suppressed, and maintenance can be easily performed. The operating rate of the entire system including this motor can be improved.

  An outer rotor magnet 108 for magnetic coupling is attached to the center of the inner peripheral surface of the outer rotor 116. The outer rotor magnet for magnetic coupling 108 is made of a magnetic metal having a configuration of 32 poles and 16 N poles and S poles alternately arranged, and is assembled to the back yoke 109. The back yoke 109 which is a magnetic coupling rotor fitted and fixed to the outer rotor 116 may be made of magnetic stainless steel or iron plated with nickel. In the present embodiment, the outer rotor magnet 108 for magnetic coupling uses a neodymium iron boron magnet plated with nickel. Further, the outer rotor magnet 108 for magnetic coupling is fastened to the outer rotor 116 with a nonmagnetic metal wedge. Therefore, no resin such as an adhesive is disposed, and even when the motor D1 is disposed in a vacuum, the released gas of the occluded impurity molecules can be extremely reduced. A magnetic shield plate 103 is attached to the outer rotor 116 so as to cover the upper part of the outer rotor magnet 108 for magnetic coupling.

  Further, an outer rotor magnet 118 is attached to the upper part of the inner peripheral surface of the outer rotor 116. The outer rotor magnet 118 is made of a magnetic metal having a configuration of 32 poles and 16 magnets of N poles and S poles arranged alternately, and is assembled to the back yoke 119. The back yoke 119 may be magnetic stainless steel or iron plated with nickel. In the present embodiment, the outer rotor magnet 118 is a neodymium iron boron magnet nickel-plated. Further, the outer rotor magnet 118 is fastened to the outer rotor 116 with a nonmagnetic metal wedge. Therefore, no resin such as an adhesive is disposed, and even when the motor D1 is disposed in a vacuum, the released gas of the occluded impurity molecules can be extremely reduced. A magnetic shield plate 130 is attached to the lower surface of the disc 112 so as to cover the upper portion of the outer rotor magnet 118.

  A stator 129 is arranged on the inner side in the radial direction of the partition wall 113 so as to face the outer rotor magnet 118. The stator 129 is attached to the main body 110. Although not shown, the stator 129 is cylindrical and includes four sets of windings of 3 slots of U phase, 3 slots of V phase, 3 slots of W phase, a total of 9 slots, that is, a total of 36 slots. Are arranged. A magnetic shield plate 102 is attached to the outer rotor 116 so as to cover the top of the stator 129.

  Since this 32-pole 36-slot motor has a slot configuration four times that of a known technology motor with a small cogging force of 8 poles and 9 slots, a small cogging force can be realized similarly. In addition, since the configuration is an even multiple of the 8-pole 9-slot motor, the same phase and the same polarity are arranged on the diagonal line of the outer rotor 116. In the 8-pole 9-slot motor, the unbalance of the magnet's attractive force may generate radial force in the bearing to be supported, and vibration may occur due to the rigidity of the bearing 114, etc. Since the unbalance force is canceled out by the same homologous poles on the diagonal line, the bearing 114 that supports the outer rotor 116 has a feature that the occurrence of vibration is suppressed without the unbalance force acting.

  Furthermore, the magnetic coupling inner rotor magnet 101 is disposed on the inner side in the radial direction of the partition wall 113 so as to face the magnetic coupling outer rotor magnet 108. The inner rotor magnet 101 for magnetic coupling is attached to the inner rotor 121 rotatably supported via a bearing 123 with respect to the cylindrical attachment portion 110b of the flange 110a of the main body 110 via a back yoke 125. . As with the coupling outer rotor magnet 108, the magnetic coupling inner rotor magnet 101 has a configuration of 32 poles and 16 N-pole and S-pole magnets are alternately arranged. Therefore, the relative rotation between the magnetic coupling inner rotor magnet 101 and the magnetic coupling outer rotor magnet 108 is fixed by the magnetic force attracting each other with the opposite poles facing each other with the partition wall 113 interposed therebetween, that is, between the two magnets. The inner rotor 121 rotates in synchronism with the back yoke 119, that is, the outer rotor 116, based on the magnetic coupling force acting in a non-contact manner.

  A detection rotor 126 for a detector for measuring a rotation angle is assembled on the inner periphery of the inner rotor 121, and resolvers 127 and 128 are attached to the outer periphery of the main body 110 so as to face the rotor. In this embodiment, the high-resolution incremental resolver 127 and the absolute resolver 128 capable of detecting the position of the rotor at one rotation are arranged in two layers. For this reason, even when the power is turned on, the rotation angle of the detection rotor 126 is known, no return to origin is required, and the electrical phase angle of the magnet with respect to the coil is known, so that the rotation angle detection used for driving current control of the motor D1 can be detected. This is possible without using a pole detection sensor.

  In the high-resolution variable reluctance resolver used in the present embodiment, the detection rotor 126 has a plurality of slot teeth having a constant pitch, and the outer peripheral surfaces of the magnetic poles of the stators of the resolvers 127 and 128 are Teeth whose magnetic poles are shifted in phase with respect to the detection rotor 126 are provided in parallel to the rotation axis, and coils are wound around the magnetic poles. When the detection rotor 126 rotates integrally with the inner rotor 121, the reluctance between the resolver 127, 128 and the magnetic pole of the stator changes, and the fundamental wave component of the change in reluctance becomes n periods in one rotation of the detection rotor 126. The reluctance change is detected, digitized by the resolver control circuit shown in FIG. 4 and used as a position signal, so that the rotation angle (or rotation speed) of the detection rotor 126, that is, the inner rotor 121 is detected. It has become. The detection rotor 126 and the resolvers 127 and 128 constitute a detector.

  In the present embodiment, the inner rotor 121 is rotationally driven in synchronism with the outer rotor 116 via a magnetic coupling. Therefore, if the rotation angle of the inner rotor 121 can be detected, the outer rotor is immediately detected. The rotation angle 116 can be obtained. The motor D1 of this embodiment is servo-controlled by a drive circuit as shown in FIG.

  In the present embodiment, the magnetic shield plates 102 and 103 have a magnetic field generated between the stator 129 and the outer rotor magnet 118 between the inner rotor magnet 101 for magnetic coupling and the outer rotor magnet 108 for magnetic coupling. It is provided to disturb the attractive force so as not to affect the magnetic coupling action. However, since the stator 129 and the outer rotor magnet 118 have 32 magnetic poles, and the magnetic coupling inner rotor magnet 101 and the magnetic coupling outer rotor magnet 108 also have 32 magnetic poles, each has the same number of magnetic poles. Even if the magnetic shield plates 102 and 103 are omitted, the attractive force between the magnetic coupling inner rotor magnet 101 and the magnetic coupling outer rotor magnet 108 is not particularly disturbed. Therefore, the magnetic shield plates 102 and 103 are particularly effective when the magnetic poles of the stator 129 and the outer rotor magnet 118 are different from the magnetic poles of the magnetic coupling inner rotor magnet 101 and the magnetic coupling outer rotor magnet 108.

  The present invention has been described above with reference to the embodiments. However, the present invention should not be construed as being limited to the above-described embodiments, and can be modified or improved as appropriate. For example, the motor of the present embodiment can be used not only in a vacuum atmosphere but also in an atmosphere outside the atmosphere. For example, in the case of a semiconductor manufacturing process, a reactive gas for etching may be introduced into the vacuum chamber after evacuation, but in the motor of the present embodiment, the inside and the outside are shielded by the partition wall. There is no possibility that the motor coil, the insulating material or the like is etched. Furthermore, in the above-described embodiment, the present invention is applied to the direct drive type motors D1 and D2 that directly output power without using a reduction gear or the like. However, the present invention is not limited to this and can be applied to a normal motor.

It is a perspective view of the frog leg arm type conveying device using the motor concerning this embodiment. It is the figure which cut | disconnected the structure of FIG. 1 by the II-II line | wire, and looked at the arrow direction. It is the figure which cut | disconnected the structure of FIG. 2 by the III-III line, and looked at the arrow direction. It is a figure which shows the example of a resolver control circuit. It is a figure which shows the example of a motor control circuit. It is a figure which shows the modification of this Embodiment. It is sectional drawing similar to FIG. 2 of the motor concerning 2nd Embodiment which can be used for the conveying apparatus shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Main body 10a Flange 11 Small disk 12 Large disk 12 Bulkhead 13 Bulkhead 14 Four-point contact ball bearing 15 Inner ring holder 16 Outer rotor 17 Outer holder 18 Outer rotor magnet 19 Back yoke 20 Stator holder 21 Inner rotor 22 Resolver holder 23 Ball Bearing 24 Inner rotor magnet 25 Back yoke 26 Detection rotor 27 Incremental resolver 28 Absolute resolver 29 Stator 30 Magnetic shield plate 41, 42 Bolt 101 Inner rotor magnet for magnetic coupling 102 Magnetic shield plate 103 Magnetic shield plate 108 Outer rotor magnet for coupling 109 Back yoke 110 Main body 110a Flange 110b Cylindrical mounting portion 111 Small disk 112 Large disk 113 Partition 114 Four-point contact ball bearing 115 Inner holder 116 Outer Motor 117 outer holder 118 outer rotor magnet 119 back yoke 121 inner rotor 123 bearing 125 back yoke 126 detection rotor 127 incremental resolver 128 absolute resolver 129 stator 130 magnetic shield plates 141, 142 bolts D1, D2 motor

Claims (5)

  A motor used in a vacuum atmosphere, wherein a predetermined surface treatment is applied to at least a bolt arranged on the vacuum atmosphere side.   The motor according to claim 1, wherein the predetermined surface treatment is at least one of heat treatment, plating, and coating.   The motor according to claim 2, wherein the predetermined surface treatment is a coating of a diamond-like carbon film.   The motor according to claim 1, wherein the bolt is a bolt for fastening a bearing or a rotating body used in a vacuum atmosphere. The motor is a direct drive motor that directly drives the rotor without using a reduction gear or the like,
A housing;
A partition wall extending from the housing and separating the air side and the vacuum atmosphere side;
An outer rotor disposed on the vacuum atmosphere side with respect to the partition;
A stator and an inner rotor disposed on the atmosphere side with respect to the partition;
A detector for detecting the rotational speed of the inner rotor,
The motor according to claim 1, wherein the stator drives the outer rotor and the inner rotor simultaneously.

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