JP4613574B2 - Motor system - Google Patents

Description

  The present invention relates to a motor system using a plurality of direct drive motors used in an atmosphere outside the atmosphere, for example, in a vacuum.

  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 direct drive motor in which a stator is arranged inside a vacuum sealing body, an output member is arranged outside thereof, and a frog leg arm is driven using an output member, that is, a rotor. Are listed. According to the direct drive motor of Patent Document 1, coil insulators and wiring coverings attached to the stator are arranged inside a vacuum seal body maintained at atmospheric pressure, and therefore when they are arranged in a vacuum chamber It is possible to avoid the problem of the storage of impure molecules and the problem of heat generation.
JP 2000-69741 A

  By the way, when a direct drive motor is installed in the vacuum chamber and the frog leg arm is directly driven, there is a problem that the height in the axial direction is limited by the structure of the vacuum chamber. In particular, in order to transfer a semiconductor wafer at a high tact time, there are cases where two coaxial frog-leg-arm type transfer devices are installed in the vacuum chamber. In such a case, the direct drive motor needs to be stacked in four axes. The motor structure of each shaft needs to be thinner and the axial distance between the shafts needs to be narrower.

  Further, in the direct drive motor of Patent Document 1, a cup-shaped partition wall is provided between the rotor and the stator so as to be separated from the atmosphere side, and a ring shape integrated with the rotor with respect to the partition wall. The boss is rotatably supported by a bearing. However, the portion of the partition located between the rotor and the stator is preferably a very thin wall in order to narrow the magnetic gap as much as possible in order to increase the amount of magnetic flux. However, if the partition wall is partially thinned, the rigidity of the partition may decrease, and the rotor may vibrate. If such a direct drive motor is applied to a frog-leg arm type transfer robot, transfer failure will occur. There is a risk of inviting.

  In addition, bearings placed in an environment separated from the atmosphere side often use solid lubrication or special lubricants, and such bearings have a shorter service life than general bearings, so maintenance is frequently performed. There is a need to do. However, when the fixed ring of the bearing is arranged on the cup-shaped partition wall, when replacing one of the bearings, it is necessary to disassemble the entire direct drive motor, and the seal member is not disassembled each time. There is a problem that must not be. In addition, after the bearing replacement, a leak test or the like for confirming the sealing performance is necessary, which requires maintenance work and lowers the operating rate of the apparatus.

  The present invention has been made in view of the problems of the prior art, and uses a direct drive motor that can detect the rotation angle of the rotor with high accuracy and further improve maintainability while avoiding atmospheric contamination. An object is to provide a motor system.

The motor system of the present invention is a motor system in which four or more direct drive motors used in an atmosphere outside the atmosphere are coaxially coupled.
Each direct drive motor
A housing;
A partition wall extending from the housing and isolating the atmosphere side from the atmosphere outside;
An outer rotor disposed outside the atmosphere with respect to the partition;
A stator disposed on the atmosphere side with respect to the partition; an inner rotor disposed on the atmosphere side with respect to the partition;
A detector that is disposed on the atmosphere side with respect to the partition wall and detects a rotational position of the inner rotor, and the outer rotor is directly driven by the stator ,
The outer rotor of one direct drive motor is supported by a bearing relative to one end of the housing, and the outer rotor of another direct drive motor is supported relative to the other end of the housing. Supported by bearings,
Furthermore, the outer rotor of at least one direct drive motor is supported by a bearing with respect to each of the outer rotors of the two direct drive motors.

According to the motor system of the present invention, in a motor system in which four or more direct drive motors used in an atmosphere outside the atmosphere are coaxially coupled, each direct drive motor extends from the housing, A partition that separates the atmosphere side from the atmosphere outside, an outer rotor disposed outside the atmosphere with respect to the partition, a stator and an inner rotor disposed on the atmosphere side with respect to the partition, and an atmosphere side with respect to the partition And a detector for detecting a rotational position of the inner rotor, the stator drives the outer rotor, and the inner rotor is rotated together with the outer rotor. By placing inside, the occlusion impurity molecules of the wiring coating are prevented from contaminating the atmosphere outside the partition wall. In addition, the outer rotor of the direct drive motor is supported by bearings at both ends of the housing, and the outer rotor of another direct drive motor is supported by bearings with respect to the outer rotor of each of the direct drive motors. As a result, the outer rotors connected by bearings have a high degree of coaxiality with each other, and the mechanical accuracy of the outer rotors connected by bearings installed at the end of the other housing is mutually high. A motor system with low interference can be provided. Therefore, when applied to a 2-axis coaxial frog-leg-arm robot, it is possible to increase the operation accuracy and increase the load.

  Further, since the shape of one end of the housing supporting the partition wall structure is such that the outer rotor of the direct drive motor can be removed in the axial direction, the outer rotor of all the direct drive motors can be removed from the partition wall. Since it can be removed, it can be easily inspected and removed, thus improving maintenance. Furthermore, since it is only necessary to remove the outer rotor outside the partition wall, it is not necessary to remove the entire direct drive motor, and a leak check or the like is not required at the time of reassembly, and the assemblability is improved.

  It is preferable that the housing can be divided into units that are commonly used in two adjacent direct drive motors because it is easy to assemble and adjustment of phase alignment of the motor and the detector is easy.

  It is preferable that the partition wall of one direct drive motor is the same as the partition wall of other direct drive motors because the number of parts and the seal location can be reduced.

  If the partition has a sealing mechanism (O-ring or the like) with the housing at both ends, the both ends of the housing can be disposed outside the atmosphere, so that the outer rotor of the direct drive motor is connected to the housing. It can be supported by bearings at both ends.

  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 transport device using a direct drive motor according to the present embodiment. In FIG. 1, four direct drive motors D1, D2, D3, and D4 are connected in series. The first arm A1 is connected to the rotor of the lowermost direct drive motor D1, and the first link L1 is pivotably connected to the tip of the first arm A1. On the other hand, the second arm A2 is connected to the rotor of the direct drive motor D2 thereon, and the second link L2 is pivotably connected to the tip of the second arm A2. Further, a first arm A1 'is connected to the rotor of the upper direct drive motor D3, and a first link L1' is pivotally connected to the tip of the first arm A1 '. Further, a second arm A2 'is connected to the rotor of the uppermost direct drive motor D4, and a 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 a wafer W is placed, and the links L1 ′ and L2 ′ are pivoted to a table T ′ on which another wafer W is placed. Connected as possible.

  As is clear from FIG. 1, if the rotors of the direct drive motors D1 and D2 rotate in the same direction, the table T also rotates in the same direction. If the rotor rotates in the opposite direction, the table T The motors D1 and D2 are approached or separated from each other. Therefore, if the direct drive 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. On the other hand, if the rotors of the direct drive motors D3 and D4 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 ′ becomes the direct drive motors D3 and D4. It comes to approach or separate. Therefore, if the direct drive motors D3 and D4 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 direct drive motors D1, D2, D3, and D4 are connected coaxially at the housing part, and the connection part is closely joined with a seal (dense joining by welding, O-ring, metal gasket, etc.), and the motor rotor It is also necessary to separate the space in which the housing is disposed from the housing external space.

  Further, in order to convey the wafer W horizontally and with little vibration, it is necessary to firmly hold the moment acting on the tips of the arms A1, A2, A1 ', A2' by the rotor support portion. In addition, when driving multiple axes in a vacuum environment, if the current arm rotation position is not recognized when the power is turned on, the arms A1, A2, A1 ′, There is a possibility of hitting A2 ′ or the like. A motor system in which direct drive motors that can meet such demands are connected coaxially will be described.

In this embodiment, a surface magnet type 32-pole 36-slot outer rotor brushless type direct drive motor is used. The slot combination of 32 poles and 36 slots has a configuration four times that of the slot combination of 8 poles and 9 slots, which is generally known to have a small cogging force but a large magnetic attraction force in the radial direction and a large vibration during rotation. It is. 2 Since the magnetic attractive force in the radial direction is canceled by increasing ⁿ times (n is an integer), vibration during rotation without increasing the roundness and coaxiality of the stator and the rotor and the rigidity of the mechanical parts Can be made small and cogging is inherently small, so that a very smooth rotation can be obtained. On the other hand, by using such a very multipolar motor, the electrical angle cycle is greater than the mechanical angle cycle, so that the positioning controllability is good. Therefore, as in the present invention, it is suitable for a direct drive motor that drives a robot apparatus without using a speed reducer. Further, since the thickness and salient pole width of the stator connecting portion and the yoke thickness of the rotor can be reduced without reducing the total magnetic flux amount, a direct drive motor having a thin and large diameter and narrow width as in the present invention is used. Is preferred.

  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. The internal structure of the 4-axis motor system will be described in detail with reference to FIG. First, the direct drive motor D1 will be described. The hollow cylindrical first main bodies 12 are fixed to each other by bolts 11 fitted into the central opening 10a of the disk 10 installed on the surface plate G. The first main body 12 has a reduced diameter portion 12h on the outer periphery of its upper end. The second main body 112 having a shape similar to that of the first main body 12 has a large-diameter portion 112h on the inner periphery of the lower end thereof. By fitting the reduced diameter portion 12h into the large diameter portion 112h, the first main body 12 and the second main body 112 are coaxially connected. The centers of the main bodies 12 and 112 can be used for passing wiring to the stator and the like. The first main body 12, the disk 10 and the second main body 112 constitute a housing.

  A disc member 110 whose central opening is closed by a lid member 101 is attached to the upper surface of the second main body 112. The disk member 110 is bolted to the lower surface of the upper end of the partition wall 13 and has a bearing holder 107 attached to the outer periphery. The disc member 110, the lid member 101, and the bearing holder 107 are made of austenitic stainless steel having high corrosion resistance. The bearing holder 107 will be described later.

  The partition wall 13 is made of stainless steel, which is a non-magnetic material, and penetrates the thick disk portion 13a attached to the disk member 110 and the direct drive motors D4, D3, D2, and D1 in the axial direction from the periphery. And a thin cylindrical portion 13b extending. A flange 13c extending from the lower surface of the disk portion 13a is TIG welded to the upper end of the cylindrical portion 13b. That is, the partition wall 13 is commonly used for the direct drive motors D1 to D4.

  The lower end of the cylindrical portion 13b is joined to the holder 15 so as to be sealed by TIG welding, and the holder 15 is fixed to the disk 10 with bolts 16. Here, by setting the welded portion of the cylindrical portion 13b to substantially the same thickness, heat is prevented from escaping only to the component on one side, and the fitting portion can be welded uniformly. The contact surface between the holder 15 and the disc 10 is provided with a groove processing for fitting the seal member. After the seal member OR is fitted into the groove, the holder 15 and the disc 10 are fastened by the bolts 16. The part is separated from the atmosphere side. The partition wall 13 is made of SUS316 made of austenitic stainless steel, which has high corrosion resistance and is less magnetic, and the holder 15 is also made of SUS316 because of its weldability with the partition wall 13.

  Further, the disk member 110 and the partition wall 13, and the partition wall 13 and the holder 15 are airtightly joined, and the holder 15 and the disk 10, and the disk 10 and the surface plate G are hermetically sealed by O-rings OR, respectively. Has been. Therefore, the internal space surrounded by the disk 10, the disk member 110, and the partition wall 13 is airtight from the outside. 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.

  A bearing holder 17 is integrally formed on the outer peripheral upper surface of the disc 10. An outer ring of a four-point contact ball bearing 19 used in a vacuum is fitted on the bearing holder 17 and fixed with bolts 20. On the other hand, the inner ring of the bearing 19 is fixed to the double cylindrical cylindrical member 23 including the first outer rotor member 21 and is fastened by a bolt 22 that fastens the first outer rotor member 21 together. . That is, the 1st outer side rotor member 21 is rotatably supported with respect to the partition 13 by the cylindrical member 23 which supports arm A1 (FIG. 1). The first outer rotor member 21 and the cylindrical member 23 constitute an outer rotor.

  The disc 10 and the bearing holder 17 are made of austenitic stainless steel having high corrosion resistance. The disc 10 also serves as a fitting and fixing device with the surface plate G serving as a chamber and a sealing device. A groove 10b for fitting the ring OR is provided.

  The bearing 19 is a four-point contact ball bearing that can load radial, axial, and moment loads with a single bearing. By using this type of bearing, only one bearing of the direct drive motor D1 is required, so that the four-axis coaxial motor system of the present invention can be thinned. The bearing 19 is made of martensitic stainless steel, which has high corrosion resistance for both the inner and outer rings and can be hardened by quenching. The rolling elements are ceramic balls, and the lubricant is vacuum grease that does not solidify even in vacuum.

  The bearing 19 may be a metal lubrication that is plated with a soft metal such as gold or silver on the inner ring and the outer ring and does not emit outgas even in a vacuum, and is a four-point contact ball bearing. The first outer rotor member 21 from the arm A1 can receive a moment in a tilting direction, but is not limited to a four-point contact type, and a cross roller, a cross ball, and a cross taper bearing can also be used. Alternatively, fluorine film treatment (DFO) may be performed to improve lubricity.

  The first outer rotor member 21 includes a permanent magnet 21a, an annular yoke 21b made of a magnetic material for forming a magnetic path, and a wedge made of a non-magnetic material for mechanically fastening the permanent magnet 21a and the yoke 21b. (Not shown). The permanent magnet 21a is a segment type in which each of the N pole and S pole magnets is made of a magnetic metal and is divided into 16 poles in a 32 pole configuration, and each of the permanent magnets 21a has a sector shape. The arc centers of the inner diameter and the outer diameter are the same, but the tangential intersection of the circumferential end face is closer to the permanent magnet 21a, so that the wedge is tightened with a screw from the outer diameter side of the yoke 21b, thereby fixing the permanent magnet 21a to the yoke 21b. It is concluded to. By setting it as such a structure, a permanent magnet can be fastened without using the fixing member which generate | occur | produces outgas, such as an adhesive agent. The permanent magnet 21a is a neodymium (Nd—Fe—B) based magnet having a high energy product, and is coated with nickel in order to improve corrosion resistance. The yoke 21b is made of low carbon steel having high magnetism and is plated with nickel in order to improve rust prevention and corrosion resistance and prevent wear during bearing replacement after processing and molding.

  A first 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 first outer rotor member 21. The first stator 29 is attached to a cylindrically deformed lower portion of the flange portion 12a extending in the radial direction at the center of the main body 12, and is formed of a laminated material of electromagnetic steel plates. The motor coil is concentratedly wound after the bobbin is fitted. The outer diameter of the first stator 29 is approximately the same as or smaller than the inner diameter of the partition wall 13.

  A first inner rotor 30 is disposed adjacent to and parallel to the first stator 29. The first inner rotor 30 is rotatably supported by ball bearings 33 with respect to a resolver holder 32 that is bolted to the outer peripheral surface of the main body 12. A permanent magnet 30a is attached to the outer peripheral surface of the first inner rotor 30 via a back yoke 30b. The permanent magnet 30a is composed of 32 poles and 16 magnets of N poles and S poles alternately made of magnetic metal like the permanent magnet 21a of the first outer rotor member 21. Accordingly, the first inner rotor 30 is rotated along with the first outer rotor member 21 driven by the first stator 29.

  The bearing 33 that rotatably supports the first inner rotor 30 is a four-point contact ball bearing that can apply radial, axial, and moment loads with a single bearing. By using this type of bearing, since only one bearing is required, the direct drive motor D1 can be thinned. Since the inside of the partition wall 13 is an atmospheric environment, a bearing using grease lubrication based on general bearing steel and mineral oil can be applied.

  Since the inside of the partition wall 13 is an atmospheric environment, the permanent magnet 30a is bonded and fixed to the back yoke 30b. The permanent magnet 30a is a neodymium (Nd—Fe—B) based magnet having a high energy product, and has a nickel coating to prevent demagnetization due to rust. The yoke 30b is made of low carbon steel having high magnetism, and is chromate plated for rust prevention after processing and forming.

  Resolver rotors 34 a and 34 b are assembled as detectors for measuring the rotation angle on the inner periphery of the first inner rotor 30, and resolver stators 35 and 36 are disposed on the outer periphery of the resolver holder 32 so as to face it. Although attached, in this embodiment, the high-resolution incremental resolver stator 35 and the absolute resolver stator 36 capable of detecting which position of the rotor is located in one rotation are arranged in two layers. Therefore, even when the power is turned on, the rotation angle of the absolute resolver rotor 34b is known, no return to origin is required, and the electrical phase angle of the magnet with respect to the coil is known. Therefore, the rotation used for driving current control of the direct drive motor D1 Angle detection is possible without using a pole detection sensor.

  The resolver holder 32 and the first inner rotor 30 are made of carbon steel, which is a magnetic material, so that electromagnetic noise from the motor field and the motor coil is not transmitted to the resolver stators 35, 36 that are angle detectors. Chromate plating is applied after molding to prevent rust.

  In the high-resolution variable reluctance resolver used in the present embodiment, the incremental resolver rotor 34a has a plurality of slot teeth having a constant pitch, and an outer peripheral surface of the incremental resolver stator 35 is provided with a rotating shaft and In parallel with each magnetic pole, teeth whose phases are shifted with respect to the incremental resolver rotor 34a are provided, and a coil is wound around each magnetic pole. When the incremental resolver rotor 34a rotates integrally with the first inner rotor 30, the reluctance with the magnetic pole of the incremental resolver stator 35 changes, and the fundamental wave component of the change in reluctance becomes n cycles with one rotation of the incremental resolver rotor 34a. In this way, the change in reluctance is detected, digitized by the resolver control circuit shown in FIG. 3 and used as a position signal, whereby the rotational angle (or rotational speed) of the incremental resolver rotor 34a, that is, the first inner rotor 30 is used. Is supposed to be detected. The resolver rotors 34a and 34b and the resolver stators 35 and 36 constitute a detector.

  According to the present embodiment, the first inner rotor 30 rotates at the same speed by the magnetic coupling action with respect to the first outer rotor member 21, that is, rotates around, so that the rotation angle of the first outer rotor member 21 is increased. It can be detected through the partition wall 13. Further, in the present embodiment, the resolver alone has the bearing 33 without using the motor forming parts and the housing. Therefore, the eccentricity adjustment by the resolver alone and the position adjustment of the resolver coil are performed before being incorporated in the housing. Therefore, there is no need to provide adjustment holes and notches in the housing and both flanges.

  Next, the direct drive motor D2 will be described. Here, the first main body 12 constitutes a housing. The cylindrical member 23 of the direct drive motor D1 described above extends upward to a position where it overlaps with the direct drive motor D2, and the inner peripheral surface of the four-point contact ball bearing 19 ′ used in vacuum An outer ring is fitted in a fitting manner and is fixed by a bolt 20 '. On the other hand, the inner ring of the bearing 19 ′ is fixed by a bolt 22 ′ that fits around the circumferential surface of the double cylindrical ring-shaped member 23 ′ and fastens the second outer rotor member 21 ′ together. That is, the second outer rotor member 21 ′ is rotatably supported with respect to the partition wall 13 by the ring-shaped member 23 ′ that supports the arm A <b> 2 (FIG. 1). The second outer rotor member 21 'and the ring-shaped member 23' constitute an outer rotor.

  The bearing 19 ′ is a four-point contact ball bearing that can load radial, axial, and moment loads with a single bearing. By using this type of bearing, only one bearing of the direct drive motor D2 is required, so that the four-axis coaxial motor of the present invention can be thinned. The inner and outer rings are made of martensitic stainless steel, which has high corrosion resistance and can be hardened by quenching. The rolling elements are ceramic balls, and the lubricant is vacuum grease that does not solidify even in vacuum.

  The bearing 19 'may be made of a metal lubrication in which a soft metal such as gold or silver is plated on the inner ring and the outer ring to prevent outgassing even in a vacuum, and is a four-point contact ball bearing. The second outer rotor member 21 ′ from the arm A1 can receive a moment in the tilting direction, but is not limited to the four-point contact type, and a cross roller, a cross ball, and a cross taper bearing can also be used. May be used, or fluorine film treatment (DFO) may be performed to improve lubricity.

  The ring-shaped member 23 ′ has a surface for fitting and fixing the inner ring of the bearing 19 ′. The four-point contact ball bearing 19 'is a very thin bearing, and rotational accuracy and friction torque are greatly affected by differences in accuracy of members to be assembled and linear expansion coefficients. Therefore, in the case of the present embodiment, the inner ring of the bearing 19 ′, which is a rotating ring, is tightly fitted or intermediately fitted to a ring-shaped member 23 ′ whose processing accuracy is easily obtained and whose linear expansion coefficient is substantially the same as the bearing ring material of the bearing. The outer ring of the bearing 19 ′, which is a fixed ring, is a clearance fit on the inner periphery of the cylindrical member 23, thereby preventing a decrease in rotational accuracy of the bearing 19 ′ and an increase in friction torque due to a temperature rise. ing.

  The second outer rotor member 21 ′ is composed of a permanent magnet 21a ′, an annular yoke 21b ′ made of a magnetic material for forming a magnetic path, and a non-magnetic for fastening the permanent magnet 21a ′ and the yoke 21b ′ mechanically. It is comprised by the wedge (not shown) which consists of a magnetic body. The permanent magnet 21a 'is a segment type in which each of the N poles and the S poles is made of a magnetic metal and is divided into 16 poles, and each of the permanent magnets 21a' has a sector shape. The arc centers of the inner diameter and the outer diameter are the same, but the tangent intersection of the circumferential end surface is closer to the permanent magnet 21a ′, so that the wedge is tightened with a screw from the outer diameter side of the yoke 21b ′, thereby permanent magnet 21a ′. Is fastened to the yoke 21b '. By setting it as such a structure, a permanent magnet can be fastened without using the fixing member which generate | occur | produces outgas, such as an adhesive agent. The permanent magnet 21a 'is a neodymium (Nd-Fe-B) magnet having a high energy product, and is coated with nickel in order to improve corrosion resistance. The yoke 21b 'is made of low carbon steel having high magnetism and is plated with nickel in order to improve rust prevention and corrosion resistance and prevent wear during bearing replacement after processing and molding.

  A second 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 second outer rotor member 21'. The second stator 29 ′ is attached to the upper part of the flange 12 a that extends in the radial direction at the center of the first main body 12 and is formed of a laminated material of electromagnetic steel plates. The motor coil is concentratedly wound after the bobbin is fitted as an insulation treatment. The outer diameter of the second stator 29 ′ is approximately the same as or smaller than the inner diameter of the partition wall 13.

  A second inner rotor 30 ′ is disposed on the inner side in the radial direction of the second stator 29 ′. The second inner rotor 30 ′ is rotatably supported by a ball bearing 33 ′ with respect to a resolver holder 32 ′ that is bolted to the outer peripheral surface of the first main body 12. A permanent magnet 30a 'is attached to the outer peripheral surface of the second inner rotor 30' via a back yoke 30b '. The permanent magnet 30a 'has a configuration of 32 poles as in the case of the permanent magnet 21a' of the second outer rotor member 21 ', and 16 magnets of N and S poles are alternately made of magnetic metal. Accordingly, the second inner rotor 30 'is rotationally driven by the second stator 29' in synchronization with the second outer rotor member 21 '.

  The bearing 33 ′ that rotatably supports the second inner rotor 30 ′ is a four-point contact ball bearing that can load radial, axial, and moment loads with a single bearing. By using this type of bearing, since only one bearing is required, the direct drive motor D2 can be thinned. Since the inside of the partition wall 13 is an atmospheric environment, a bearing using grease lubrication based on general bearing steel and mineral oil can be applied.

  Since the inside of the partition wall 13 is an atmospheric environment, the permanent magnet 30a 'is fixedly bonded to the back yoke 30b'. The permanent magnet 30a 'is a neodymium (Nd-Fe-B) based magnet having a high energy product, and is coated with nickel to prevent demagnetization due to rust. The yoke 30b 'is made of a low-carbon steel having high magnetism, and is chromated for rust prevention after work forming.

  A resolver rotor 34b ′ is assembled as a detector for measuring a rotation angle on the inner periphery of the second inner rotor 30 ′, and the resolver stator 35 ′, In this embodiment, the high-resolution incremental resolver stator 35 'and the absolute resolver stator 36' that can detect the position of the rotor in one rotation are arranged in two layers. ing. Therefore, even when the power is turned on, the rotational angle of the absolute resolver rotor 34 'is known, no return to origin is required, and the electrical phase angle of the magnet with respect to the coil is known. Therefore, the relative rotational angle of the direct drive motor D2 is This is possible without using a detection sensor.

  The resolver holder 32 ′ and the second inner rotor 30 ′ are made of carbon steel, which is a magnetic body, so that electromagnetic noise from the motor field and the motor coil is not transmitted to the resolver stators 35 ′, 36 ′, which are angle detectors. The material is chromate plated for rust prevention after processing and molding.

  According to the present embodiment, the second inner rotor 30 ′ rotates at the same speed by the magnetic coupling action with respect to the second outer rotor member 21 ′. The rotation angle can be detected through the partition wall 13. Further, in the present embodiment, the resolver alone has the bearing 33 ′ without using the motor forming parts and the housing. Therefore, before being incorporated in the housing, the eccentricity adjustment and the position of the resolver coil by the resolver alone are provided. Since adjustments such as adjustment can be performed, there is no need to provide adjustment holes or notches in the housing and both flanges.

  In the high-resolution variable reluctance resolver used in the present embodiment, the incremental resolver rotor 34a ′ has a plurality of slot teeth having a constant pitch, and the outer peripheral surface of the incremental resolver stator 35 ′ is rotated. Teeth whose magnetic poles are shifted in phase with respect to the incremental resolver rotor 34a ′ at each magnetic pole in parallel with the axis are provided, and a coil is wound around each magnetic pole. When the incremental resolver rotor 34a ′ rotates integrally with the first inner rotor 30, the reluctance with the magnetic pole of the incremental resolver stator 35 ′ changes, and the fundamental wave component of the reluctance change becomes n by one rotation of the incremental resolver rotor 34a ′. The change in the reluctance is detected in such a manner that it is digitized by the resolver control circuit shown in FIG. 3 and used as a position signal, so that the rotational angle of the incremental resolver rotor 34a ′, that is, the first inner rotor 30 ( (Or rotational speed) is detected. The resolver rotors 34a 'and 34b' and the resolver stators 35 'and 36' constitute a detector.

  The first stator 29 and the second stator 29 'are arranged vertically with the flange portion 12a as the center, and the resolver is arranged on the inner side in the radial direction. The first main body 12 has a hollow structure, and the flange portion 12a is provided with at least one radial through hole 12d communicating with the center, through which the motor wiring is connected to the first main body 12. It has a structure that pulls out to the center of the. On the other hand, at least one notch 12e, 12e is provided at each end of the first main body 12, and the resolver wiring is drawn out to the center of the first main body 12 through these notches. With this structure, it is possible to arrange the resolver of the direct motor D1, the stator 29, the stator 29 ′ of the direct motor D2, and the resolver in this order from the housing side. The angle of the stator and resolver can be adjusted. Therefore, if a facility for rotationally driving the reference outer rotor is prepared separately, the angle of the resolver relative to the stator can be adjusted with high accuracy by setting the first main body 12 incorporating the stator and the resolver in the facility. Therefore, it is possible to prevent the angle positioning accuracy from being lowered due to the deviation of the commutation and to enhance the compatibility of the drive control circuit with the four-axis coaxial motor of the present invention.

  FIG. 4 is a block diagram showing a drive circuit for the direct drive motors D1 and D2. When a motor rotation command is input from an external computer, the motor control circuit DMC1 for the direct drive motor D1 and the motor control circuit DMC2 for the direct drive motor D2 respectively drive signals from the CPU to the three-layer amplifier (AMP). Is output from the three-layer amplifier (AMP) to the direct drive motors D1 and D2. As a result, the outer rotor members 21 and 21 'of the direct drive motors D1 and D1 rotate independently to move the arms A1 and A2 (FIG. 1). When the outer rotor members 21, 21 ′ rotate, resolver signals are output from the resolver stators 35, 36, 35 ′, 36 ′ whose rotation angles have been detected as described above, and are output to the resolver digital converter (RDC). The CPU input after the digital conversion in step 1 determines whether or not the outer rotor members 21 and 21 'have reached the command position, and stops the drive signal to the three-layer amplifier (AMP) if the command position is reached. Thus, the rotation of the outer rotor members 21 and 21 ′ is stopped. This enables servo control of the outer rotor members 21 and 21 '.

  When driving multiple axes in a vacuum environment, there is a possibility that the arm A1 or the like may hit the wall of the vacuum chamber or the shutter of the vacuum chamber if the current rotational positions of the arms A1 and A2 are not recognized when the power is turned on. However, in the present embodiment, the variable reluctance comprising the absolute resolver stators 36 and 36 ′ for detecting the absolute position of one rotation of the rotating shaft and the incremental resolver stators 35 and 35 ′ for detecting the rotational position with finer resolution. Since the mold resolver is employed, the rotational position control of the outer rotor members 21, 21 ′, that is, the arms A1 and A2, can be performed with high accuracy.

  Here, the resolver is adopted for detecting the rotation of the inner rotor 30. However, since the detector can be arranged on the atmosphere side inside the partition wall 13, a servo motor generally used for high-precision positioning is driven with high precision 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.

  Next, the direct drive motor D4 will be described. An outer ring of a four-point contact ball bearing 119 used in vacuum is fitted to a bearing holder 107 that is detachably bolted to the disk member 110 attached to the second main body 112. The bolt 120 is fixed. On the other hand, the inner ring of the bearing 119 is fixed to a double cylindrical cylindrical member 123 that includes the first outer rotor member 121 and is fastened by a bolt 122 that fastens the first outer rotor member 121 together. . That is, the first outer rotor member 121 is rotatably supported with respect to the partition wall 113 by the cylindrical member 123 that supports the arm A <b> 2 ′ (FIG. 1). The first outer rotor member 121 and the cylindrical member 123 constitute an outer rotor.

  The bearing holder 107 is made of austenitic stainless steel having high corrosion resistance. The bearing 119 is a four-point contact ball bearing that can load radial, axial, and moment loads with a single bearing. By using this type of bearing, only one bearing of the direct drive motor D4 is required, so that the four-axis coaxial motor system of the present invention can be thinned. The bearing 119 is made of martensitic stainless steel, which has high corrosion resistance for both the inner and outer rings and can be hardened by quenching. The rolling elements are ceramic balls, and the lubricant is vacuum grease that does not solidify even in vacuum.

  Note that the bearing 119 may be a metal lubrication that is plated with a soft metal such as gold or silver on the inner ring and the outer ring and does not emit outgas even in a vacuum, and is a four-point contact ball bearing. The first outer rotor member 121 can receive a moment in the tilting direction from the arm A2 ′, but is not limited to a four-point contact type, and a cross roller, a cross ball, and a cross taper bearing can also be used. You may use, and you may perform a fluorine-type film processing (DFO) for lubricity improvement.

  The first outer rotor member 121 includes a permanent magnet 121a, an annular yoke 121b made of a magnetic material for forming a magnetic path, and a wedge made of a non-magnetic material for mechanically fastening the permanent magnet 121a and the yoke 121b. (Not shown). The permanent magnet 121a is a segment type in which each of the N pole and S pole magnets is made of a magnetic metal and is divided into 16 poles, each of which has a sector shape. The arc centers of the inner diameter and the outer diameter are the same, but the tangent intersection of the circumferential end face is closer to the permanent magnet 121a, so that the wedge is tightened with a screw from the outer diameter side of the yoke 121b, thereby fixing the permanent magnet 121a to the yoke 121b. It is concluded to. By setting it as such a structure, a permanent magnet can be fastened without using the fixing member which generate | occur | produces outgas, such as an adhesive agent. The permanent magnet 121a is a neodymium (Nd—Fe—B) based magnet having a high energy product, and is coated with nickel in order to enhance corrosion resistance. The yoke 121b is made of a low-carbon steel having high magnetism and is plated with nickel in order to improve rust prevention and corrosion resistance and prevent wear during bearing replacement after processing and molding.

  A first stator 129 is disposed on the inner side in the radial direction of the partition wall 113 so as to face the inner peripheral surface of the first outer rotor member 121. The first stator 129 is attached to a cylindrically deformed lower portion of a flange portion 112a that extends in the radial direction at the center of the main body 112, and is formed of a laminated material of electromagnetic steel plates. The motor coil is concentratedly wound after the bobbin is fitted. The outer diameter of the first stator 129 is approximately the same as or smaller than the inner diameter of the partition wall 13.

  A first inner rotor 130 is disposed adjacent to and parallel to the first stator 129. The first inner rotor 130 is rotatably supported by a ball bearing 133 with respect to a resolver holder 132 that is bolted to the outer peripheral surface of the second main body 112. A permanent magnet 130a is attached to the outer peripheral surface of the first inner rotor 130 via a back yoke 130b. The permanent magnet 130a has a 32-pole configuration, like the permanent magnet 121a of the first outer rotor member 121, and has 16 N-pole and S-pole magnets alternately made of magnetic metal. Accordingly, the first inner rotor 130 is rotated along with the first outer rotor member 121 driven by the first stator 129.

  The bearing 133 that rotatably supports the first inner rotor 130 is a four-point contact ball bearing that can load radial, axial, and moment loads with a single bearing. By using this type of bearing, since only one bearing is required, the direct drive motor D4 can be thinned. Since the inside of the partition wall 13 is an atmospheric environment, a bearing using grease lubrication based on general bearing steel and mineral oil can be applied.

  Since the inside of the partition wall 13 is an atmospheric environment, the permanent magnet 130a is bonded and fixed to the back yoke 130b. The permanent magnet 130a is a neodymium (Nd—Fe—B) based magnet having a high energy product, and is coated with nickel to prevent demagnetization due to rust. The yoke 130b is made of low-carbon steel having high magnetism, and is chromate-plated for rust prevention after work forming.

  Resolver rotors 134a and 134b are assembled as detectors for measuring the rotation angle on the inner circumference of the first inner rotor 130, and resolver stators 135 and 136 are placed on the outer circumference of the resolver holder 132 so as to face it. Although attached, in this embodiment, the high-resolution incremental resolver stator 135 and the absolute resolver stator 136 that can detect at which position of the rotor is located in one rotation are arranged in two layers. Therefore, even when the power is turned on, the rotation angle of the absolute resolver rotor 134b is known, no return to origin is required, and the electrical phase angle of the magnet with respect to the coil is known. Therefore, the rotation used for controlling the drive current of the direct drive motor D4 Angle detection is possible without using a pole detection sensor.

  The resolver holder 132 and the first inner rotor 130 are made of carbon steel, which is a magnetic material, so that electromagnetic noise from the motor field and the motor coil is not transmitted to the resolver stators 135, 136 that are angle detectors. Chromate plating is applied after molding to prevent rust.

  In the high-resolution variable reluctance resolver used in the present embodiment, the incremental resolver rotor 134a has a plurality of slot teeth having a constant pitch, and an outer peripheral surface of the incremental resolver stator 135 has a rotating shaft and In parallel, teeth whose phases are shifted with respect to the incremental resolver rotor 134a at each magnetic pole are provided, and a coil is wound around each magnetic pole. When the incremental resolver rotor 134a rotates integrally with the first inner rotor 130, the reluctance with the magnetic pole of the incremental resolver stator 135 changes, and the fundamental wave component of the reluctance change becomes n cycles with one rotation of the incremental resolver rotor 134a. In this way, the change in reluctance is detected, digitized by the resolver control circuit shown in FIG. 3 and used as a position signal, whereby the rotational angle (or rotational speed) of the incremental resolver rotor 134a, that is, the first inner rotor 130 is used. Is supposed to be detected. The resolver rotors 134a and 134b and the resolver stators 135 and 136 constitute a detector.

  According to the present embodiment, the first inner rotor 130 rotates at the same speed by the magnetic coupling action with respect to the first outer rotor member 121, that is, rotates with the first outer rotor member 121. It can be detected through the partition wall 13. Further, in the present embodiment, the resolver alone has the bearing 133 without using the motor forming parts and the housing, and therefore, the eccentricity adjustment and the resolver coil position adjustment with the resolver alone before being incorporated in the housing. Therefore, there is no need to provide adjustment holes and notches in the housing and both flanges.

  Next, the direct drive motor D3 will be described. Here, the second main body 112 constitutes a housing. The cylindrical member 123 of the direct drive motor D4 described above extends downward to a position where it overlaps with the direct drive motor D3, and the inner peripheral surface of a four-point contact ball bearing 119 ′ used in vacuum The outer ring is fitted in a fitting manner and fixed by a bolt 120 ′. On the other hand, the inner ring of the bearing 119 'is fixed by a bolt 122' that fits around the circumferential surface of the double cylindrical ring-shaped member 123 'and fastens the second outer rotor member 121' together. That is, the second outer rotor member 121 ′ is rotatably supported with respect to the partition wall 13 by the ring-shaped member 123 ′ that supports the arm A <b> 1 ′ (FIG. 1). The second outer rotor member 121 'and the ring-shaped member 123' constitute an outer rotor.

  The bearing 119 ′ is a four-point contact ball bearing that can apply radial, axial, and moment loads with a single bearing. By using this type of bearing, only one bearing of the direct drive motor D3 is required, so that the four-axis coaxial motor of the present invention can be thinned. The inner and outer rings are made of martensitic stainless steel, which has high corrosion resistance and can be hardened by quenching. The rolling elements are ceramic balls, and the lubricant is vacuum grease that does not solidify even in vacuum.

  The bearing 119 ′ may be made of a metal lubricated by plating a soft metal such as gold or silver on the inner ring and the outer ring so as not to release outgas even in a vacuum, and is a four-point contact ball bearing. The second outer rotor member 121 ′ can receive a moment in the tilting direction from the arm A 1 ′, but is not limited to a four-point contact type, and a cross roller, a cross ball, and a cross taper bearing can also be used. You may use in a state, and you may perform a fluorine-type film processing (DFO) for lubricity improvement.

  The second outer rotor member 121 ′ includes a permanent magnet 121a ′, an annular yoke 121b ′ made of a magnetic material for forming a magnetic path, and a non-magnetic for fastening the permanent magnet 121a ′ and the yoke 121b ′ mechanically. It is comprised by the wedge (not shown) which consists of a magnetic body. The permanent magnet 121a 'is a segment type in which each of the N pole and S pole magnets is made of a magnetic metal and is divided into 16 poles in a 32 pole configuration, and each of the permanent magnets 121a' has a sector shape. The arc centers of the inner diameter and the outer diameter are the same, but the tangent intersection of the circumferential end face is closer to the permanent magnet 121a ′, so that the wedge is tightened with a screw from the outer diameter side of the yoke 121b ′ so that the permanent magnet 121a ′. Is fastened to the yoke 121b '. By setting it as such a structure, a permanent magnet can be fastened without using the fixing member which generate | occur | produces outgas, such as an adhesive agent. The permanent magnet 121a 'is a neodymium (Nd-Fe-B) magnet having a high energy product, and is coated with nickel in order to improve corrosion resistance. The yoke 121b 'is made of low carbon steel having high magnetism, and is plated with nickel in order to improve rust prevention and corrosion resistance and prevent wear during bearing replacement after processing and molding.

  A second stator 129 ′ 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 second outer rotor member 121 ′. The second stator 129 ′ is attached to a cylindrical deformed upper portion of the flange portion 112a extending in the radial direction at the center of the second main body 112. The second stator 129 ′ is formed of a laminated material of electromagnetic steel plates, and is attached to each salient pole. The motor coil is concentratedly wound after the bobbin is fitted as an insulation treatment. The outer diameter of the second stator 129 ′ is approximately the same as or smaller than the inner diameter of the partition wall 13.

  A second inner rotor 130 ′ is disposed on the inner side in the radial direction of the second stator 129 ′. The second inner rotor 130 ′ is rotatably supported by a ball bearing 133 ′ with respect to a resolver holder 132 ′ that is bolted to the outer peripheral surface of the second main body 112. A permanent magnet 130a 'is attached to the outer peripheral surface of the second inner rotor 130' via a back yoke 130b '. The permanent magnet 130a 'has a configuration of 32 poles, like the permanent magnet 121a' of the second outer rotor member 121 ', and is composed of 16 magnetic poles each having 16 N poles and S poles. Therefore, the second inner rotor 130 'is driven to rotate in synchronization with the second outer rotor member 121' by the second stator 129 '.

  The bearing 33 ′ that rotatably supports the second inner rotor 30 ′ is a four-point contact ball bearing that can load radial, axial, and moment loads with a single bearing. By using this type of bearing, since only one bearing is required, the direct drive motor D3 can be thinned. Since the inside of the partition wall 13 is an atmospheric environment, a bearing using grease lubrication based on general bearing steel and mineral oil can be applied.

  Since the inside of the partition wall 13 is an atmospheric environment, the permanent magnet 130a 'is fixedly bonded to the back yoke 130b'. The permanent magnet 130a 'is a neodymium (Nd-Fe-B) magnet having a high energy product, and is coated with nickel to prevent demagnetization due to rust. The yoke 130b 'is made of low carbon steel having high magnetism, and is chromate plated for rust prevention after work forming.

  Resolver rotors 134a ′ and 134b ′ are assembled as detectors for measuring the rotation angle on the inner periphery of the second inner rotor 130 ′, and the resolver stator 132 ′ is disposed on the outer periphery of the resolver holder 132 ′ so as to face it. In this embodiment, two layers of the high-resolution incremental resolver stator 135 ′ and the absolute resolver stator 136 ′ that can detect the position of the rotor in one rotation are provided. Is arranged. For this reason, even when the power is turned on, the rotation angle of the detection rotor 134 'is known, no return to origin is required, and the electrical phase angle of the magnet with respect to the coil is known, so the relative rotation angle of the direct drive motor D3 can be detected by pole detection. This is possible without using a sensor.

  The resolver holder 132 ′ and the second inner rotor 130 ′ are made of carbon steel, which is a magnetic material, so that electromagnetic noise from the motor field and motor coil is not transmitted to the resolver stators 135 ′ and 136 ′ that are angle detectors. The material is chromate plated for rust prevention after processing and molding.

  According to the present embodiment, the second inner rotor 130 ′ rotates at the same speed by the magnetic coupling action with respect to the second outer rotor member 121 ′. The rotation angle can be detected through the partition wall 13. Further, in the present embodiment, the resolver alone has the bearing 133 ′ without using a motor-forming component or housing, and therefore, before being incorporated in the housing, the eccentricity adjustment and the position of the resolver coil by the resolver alone are provided. Since adjustments such as adjustment can be performed, there is no need to provide adjustment holes or notches in the housing and both flanges.

  In the high-resolution variable reluctance resolver used in the present embodiment, the incremental resolver rotor 134a ′ has a plurality of slot teeth having a constant pitch, and is provided on the outer circumferential surface of the magnetic pole of the incremental resolver stator 135 ′. In addition, teeth that are out of phase with respect to the incremental resolver rotor 134a ′ at each magnetic pole are provided in parallel with the rotation axis, and a coil is wound around each magnetic pole. When the incremental resolver rotor 134a ′ rotates integrally with the second inner rotor 130 ′, the reluctance with the magnetic pole of the incremental resolver stator 135 ′ changes, and the fundamental wave component of the reluctance change is changed by one rotation of the incremental resolver rotor 134a ′. The change in reluctance is detected so that there are n cycles, digitized by the resolver control circuit shown in FIG. 3 as an example, and used as a position signal to rotate the incremental resolver rotor 134a ′, that is, the second inner rotor 130 ′. An angle (or rotational speed) is detected. The resolver rotors 134a 'and 134b' and the resolver stators 135 'and 136' constitute a detector.

  The first stator 129 and the second stator 129 'are arranged vertically with the flange portion 112a as the center, and the resolver is arranged on the inner side in the radial direction. The second body 112 has a hollow structure, and the flange portion 112a is provided with at least one radial through hole 112d communicating with the center, through which the motor wiring is routed to the second body 112. It has a structure that pulls out to the center of the. On the other hand, at least one notch 112e, 112e is provided at each end of the second body 112, and the resolver wiring is drawn out to the center of the second body 112 through these. With this structure, it is possible to arrange the resolver of the direct motor D4, the stator 129, the stator 129 ′ of the direct motor D3, and the resolver in this order from the housing side. The angle of the stator and resolver can be adjusted. Therefore, if a facility for rotationally driving the reference outer rotor is prepared separately, the angle of the resolver relative to the stator can be adjusted with high accuracy by setting the second main body 112 incorporating the stator and the resolver in the facility. Therefore, it is possible to prevent the angle positioning accuracy from being lowered due to the deviation of the commutation and to enhance the compatibility of the drive control circuit with the four-axis coaxial motor of the present invention.

  FIG. 4 is a block diagram showing a drive circuit for the direct drive motors D1 and D2. When a motor rotation command is input from an external computer, the motor control circuit DMC1 for the direct drive motor D3 and the motor control circuit DMC2 for the direct drive motor D4 respectively drive signals from the CPU to the three-layer amplifier (AMP). Is output from the three-layer amplifier (AMP) to the direct drive motors D3 and D4. As a result, the outer rotor members 121 and 121 'of the direct drive motors D3 and D4 rotate independently to move the arms A1' and A2 '(FIG. 1). When the outer rotor members 121 and 121 ′ rotate, resolver signals are output from the resolver stators 135, 136, 135 ′, and 136 ′ that have detected the rotation angles as described above. The resolver digital converter (RDC) The CPU that has been input after digital conversion determines whether or not the outer rotor members 121 and 121 ′ have reached the command position, and stops the drive signal to the three-layer amplifier (AMP) if the command position is reached. Thus, the rotation of the outer rotor members 121 and 121 ′ is stopped. This enables servo control of the outer rotor members 121 and 121 '.

  When driving multiple axes in a vacuum environment, if the current rotation position of the arms A1 ′ and A2 ′ is not recognized when the power is turned on, the arm A1 ′ or the like is hit against the wall of the vacuum chamber or the shutter of the vacuum chamber. In this embodiment, the absolute resolver stators 136 and 136 ′ that detect the absolute position of one rotation of the rotating shaft and the incremental resolver stators 135 and 135 ′ that detect the rotational position with finer resolution are used. Since the variable reluctance resolver is employed, the rotational position control of the outer rotor members 121 and 121 ′, that is, the arms A1 ′ and A2 ′ can be performed with high accuracy.

  Here, the resolver is adopted for detecting the rotation of the inner rotor 130. However, since the detector can be disposed on the atmosphere side inside the partition wall 13, the servo motor generally used for high-precision positioning is driven with high precision 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.

  The cylindrical member 123 constituting the outer rotor of the (first) direct drive motor D4 closest to the upper end of the motor system according to the present embodiment is detachably attached to the housing (here, the cylindrical member 110). The outer diameter part 110a of the mounting seat surface of the bearing holder 107 in the cylindrical member 110 is positioned in the radial direction from the thin cylindrical part 13b. Therefore, if the bearing holder 107 is removed, the cylindrical member 123 ′ of the direct drive motor D3 supported by the bearing 119 ′ together with the cylindrical member 123 of the direct drive motor D4 is integrated with the outer rotor members 121 and 121 ′. In addition, the direct drive motors D2 and D1 can be removed from the partition wall 13 and then the inspection and removal can be easily performed, thereby improving the maintainability. Furthermore, since only the bearing holder 107 needs to be removed, there is no need to remove the partition wall structure, and a leak check or the like is not required at the time of reassembly, thereby improving the assemblability.

  In the housing of the present embodiment, the first main body 12 and the second main body 112 are connectable in an arbitrary phase in the axial direction, that is, two adjacent direct drive motors D1, D2, and D3. Each unit commonly used in D4 is detachably fixed with a bolt. The first main body 12 includes, in order from the disk 10, the angle detector of the direct drive motor D1, the stator of the direct drive motor D1, the stator of the direct drive motor D2, and the angle detector of the direct drive motor D2. In this order, and the second main body 112, in order from the first main body 12 side, an angle detector of the direct drive motor D3 axis, a stator of the direct drive motor D3 axis, a stator of the direct drive motor D4, a direct drive It becomes possible to arrange in the order of the angle detector of the motor D4, and the angle of the angle detector with respect to the stator can be easily adjusted for each axis. Therefore, if a facility for rotationally driving the reference motor rotor is prepared separately, by setting the first main body or the second main body incorporating the motor stator and the rotation detector in the equipment, In addition, since the angle adjustment of the angle detector with respect to the motor stator can be performed with high accuracy, the deterioration of the angle positioning accuracy due to the deviation of the commutation is prevented, the adjustment after assembly is easy or unnecessary, and the drive for the four-axis coaxial motor of the present invention Control circuit compatibility can be increased

  In the above embodiment, the example using the surface magnet type 32-pole 36-slot outer rotor brushless motor has been described. However, the present invention is not limited to this type of motor, and any brushless motor can be applied. Other magnetic pole types, for example, a permanent magnet embedded type, other slot combinations, or an inner rotor type may be used.

  Further, as a countermeasure against interference of each axis, a configuration may be adopted in which the number of rotor poles and the number of slots of adjacent axes in the axial direction are different. For example, in the case of 4-axis coaxial, the first axis is 32 poles and 36 slots, the second axis is 24 poles and 27 slots, and in the case of 4-axis coaxial, the first axis and the third axis are 32 poles and 36 slots, and the second axis If the fourth axis has a configuration of 24 poles and 27 slots, it is possible to prevent mutual interference such as generation of thrust in the rotating direction on the rotor and the magnetic coupling device due to the magnetic field of each axis.

  The rotor permanent magnet is a neodymium (Nd-Fe-B) -based magnet and has been described using a nickel coating as an example of a coating for enhancing corrosion resistance. However, the material is limited to this material and surface treatment. However, it should be changed as appropriate depending on the environment in which it is used. For example, a samarium-cobalt (Sm · Co) -based magnet that is difficult to demagnetize at high temperatures should be used depending on the temperature conditions during baking. If used in ultra-vacuum, a titanium nitride coating with a high outgas barrier should be applied.

  In addition, the yoke has been described using an example in which nickel is plated with low carbon steel as a material. However, the yoke is not limited to this material and surface treatment, and may be appropriately changed depending on the environment used. In particular, regarding surface treatment, if it is used in ultra-vacuum, it should be subjected to Kanigen plating, clean s plating, titanium nitride coating, etc. with few pinholes.

  The method of fastening the permanent magnet to the yoke has been described using an example in which a non-magnetic wedge is tightened with a screw from the outer diameter side of the yoke, but it is appropriately changed depending on the environment in which it is used. May be bonded or other fastening methods.

  Further, the bearings 19, 19 ′, 119, and 119 ′ have been described using examples of four-point contact ball bearings of grease lubrication for vacuum, but are not limited to this type, material, and lubrication method, and are used. It can be changed as appropriate according to the environment, load conditions, rotational speed, etc., and may be a cross roller bearing. In the case of a 4-axis coaxial motor, it is supported by another bearing to further increase mechanical rigidity. If a multi-point contact bearing cannot be used, such as when rotating at high speed, such as when rotating at high speed, a bearing that supports the rotor of each axis and another bearing can be preloaded as a deep groove ball bearing or an angular bearing. In addition, when used in an ultra-vacuum, a metal lubrication that does not release gas, such as plating of a soft metal such as gold or silver, may be used.

  In addition, the inner rotor functioning as a magnetic coupling has been described as using a permanent magnet and a back yoke. However, the material and shape of the permanent magnet and the back yoke are not limited thereto. For example, depending on the mass of the resolver and the friction torque of the bearing, the number of poles may not be the same as that of the outer rotor, or the width may not be the same. A salient pole that does not use a permanent magnet may be used.

  Further, although an example in which a resolver is used as an angle detector has been described, it can be appropriately changed depending on manufacturing cost and resolution, and for example, an optical rotary encoder may be used.

  Moreover, although the example which used the grease lubrication 4-point contact ball bearing was demonstrated as bearing 33,33 ', 133,133' which supports the rotation side of an angle detector rotatably, it is limited to this form and a lubrication method. However, if the multipoint contact bearing cannot be used, such as high-speed rotation or reduction of friction torque, it can be changed appropriately depending on the installation space, friction torque, rotation speed, etc. A structure may be adopted in which two deep groove ball bearings are arranged for each axis to apply a preload.

  In addition to the other partition walls, the structural parts and the material, shape, and manufacturing method of the partition parts and the partition walls are appropriately changed depending on the manufacturing cost, the environment used, the load conditions, the configuration, and the like.

  In the motor system described above, magnetic flux leaking from the magnetic couplings used in the rotors, stators, and resolvers of each axis does not generate thrust in the rotational direction in the magnetic couplings used in the rotors and rotation detectors. In addition, a magnetic shield for shielding each other's magnetic field is arranged between the rotors of each shaft, and the electromagnetic waves generated from the rotor, stator, and resolver of each shaft are not interfered with each other's resolver. Magnetic interference generated between each axis can be prevented by arranging a magnetic shield to shield the field, or changing the number of rotor poles and the number of stator slots between adjacent axes in the axial direction. Thus, the axial length of each axis and the axial distance of each axis can be shortened. Therefore, although it is a multi-axis coaxial motor system such as a 4-axis coaxial system and a 4-axis coaxial system, a configuration in which the overall axial length is suppressed is possible. In particular, in a system using a multi-axis direct drive motor such as a 4-axis coaxial system, two frog-leg-arm robots that can perform high-precision positioning without greatly changing the chamber structure can be installed. The operating rate can be increased. Needless to say, it can be used for a motor system with four or more axes.

  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 direct drive 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 direct drive motor of the present embodiment, the inside and the outside are shielded by the partition wall. Therefore, there is no possibility that the motor coil, the insulating material, and the like are etched.

It is a perspective view of the frog leg arm type conveying device using the direct drive 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 a figure which shows the example of a resolver control circuit. It is a figure which shows the example of a motor control circuit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Disc 11, 111 Bolt 12, 112 Main body 12a, 112a Flange part 13 Bulkhead 13a Disc part 13b Cylindrical part 17, 107 Bearing holder 19, 19 ', 119, 119' Four-point contact ball bearing 21, 21 ', 121 121 ′ Outer rotor member 23 ′, 123 ′ Ring-shaped member 23, 123 Cylindrical member 29, 29 ′, 129, 129 ′ Stator 30, 30 ′, 130, 130 ′ Inner rotor 32, 32 ′, 132, 132 ′ Resolver holder 33, 33 ', 133, 133' Bearing 34, 34 ', 134, 134' Detection rotor 34a, 34a ', 134a, 134a' Incremental resolver rotor 34b, 34b ', 134b, 134b' Absolute resolver rotor 35, 35 ', 135, 135' Incremental resolver stator 36, 36 ', 1 6, 136 'absolute resolver stator 101 Lid member 110 Disk members A1, A2, A1', A2 'Arms D1, D2, D3, D4 Direct drive motor DMC1 Motor control circuit DMC2 Motor control circuit G Surface plates L1, L2, L1 ', L2' link OR O-ring T, T 'table

Claims (5)

In a motor system in which four or more direct drive motors used in an atmosphere outside the atmosphere are coaxially coupled,
Each direct drive motor
A housing;
A partition wall extending from the housing and isolating the atmosphere side from the atmosphere outside;
An outer rotor disposed outside the atmosphere with respect to the partition;
A stator disposed on the atmosphere side with respect to the partition; an inner rotor disposed on the atmosphere side with respect to the partition;
A detector that is disposed on the atmosphere side with respect to the partition wall and that detects a rotational position of the inner rotor, and the outer rotor is directly driven by the stator ,
The outer rotor of one direct drive motor is supported by a bearing relative to one end of the housing, and the outer rotor of another direct drive motor is supported relative to the other end of the housing. Supported by bearings,
Furthermore, the outer rotor of at least one direct drive motor is supported by a bearing with respect to each of the outer rotors of the two direct drive motors.   2. The motor system according to claim 1, wherein an end shape of any one of the housings is configured such that the outer rotors of all the direct drive motors are detachable in an axial direction.   The motor system according to claim 1, wherein the housing can be divided into units commonly used in two adjacent direct drive motors.   The motor system according to claim 1, wherein the partition wall of one direct live motor is common to the partition walls of other direct drive motors.   The motor system according to claim 1, wherein a sealing mechanism for the housing is provided at both ends of the partition wall.

Images