JP2009303331A - Direct drive motor and scara robot - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a direct drive motor which can ensure rigidity required for a robot, has high reliability and is used in an atmosphere other than that at the atmospheric pressure while avoiding atmospheric contamination due to fixation of a magnetic pole: and to provide a scara robot. <P>SOLUTION: In a three-stage brushless motor BM1 coupled in series, at least two among a stator 29, an atmospheric bearing device 33, an atmosphere side rotor 30, angle detectors 35, 36, a motor rotor 21 and a vacuum bearing device 19 are disposed at positions where at least one part can be superimposed in a motor axial line direction. With this configuration, the direct drive motor can ensure high rigidity even with a compact configuration. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a direct drive motor and a scalar robot provided with a surface magnet type brushless motor, and more particularly to a direct drive motor and a scalar robot suitable for a transfer robot used in an atmosphere outside the atmosphere such as 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.

  On the other hand, conventionally, as means for driving a frog-leg-arm robot in a vacuum chamber separated and isolated from the atmosphere side, cups such as a bellows drive system, a magnetic coupling drive system, and a magnetic fluid seal drive system are used. A method has been used in which the outputs of multiple motors arranged in the atmosphere are combined into a multi-structure shaft through a ring mechanism and a seal mechanism, and the multi-structure shaft is introduced into a vacuum chamber.

  However, when a coupling mechanism such as the above-described bellows drive system or magnetic coupling drive system is used, the backlash is large and the torsional rigidity in the rotational direction is low, so that a high positioning accuracy cannot be obtained. On the other hand, in the case of the method in which the concave rolling force is introduced through the sealing mechanism, outgassing due to the volatile component contained in the sealing material is generated and it is difficult to apply to the ultrahigh vacuum chamber. . Therefore, as shown in Patent Document 1, a direct drive motor has been developed in which a partition for separating and separating from the atmosphere side is arranged between the rotor and the stator, thereby suppressing generation of outgas.

On the other hand, as shown in Patent Document 2, for example, a method of installing a motor in an atmosphere separated from the atmosphere side and transmitting a driving force from the multiple shaft structure into the chamber has been developed.
JP 2006-26057 A Special Table 2002-534282

  Here, it is conceivable to improve the three-axis motor of Patent Document 2 by diverting the technique of Patent Document 1. However, in the case of a three-axis motor in which a partition for separating and separating from the atmosphere side is arranged between the rotor and the stator, when the bearing is arranged on each rotor, the fixed ring of the bearing is the chamber side shaft. It can be fixed to a highly rigid member such as a motor base, but the other shaft must be fixed to a thin tubular partition with low rigidity. When applied to a transfer robot such as a scalar arm type, it is mechanical. It was difficult to increase rigidity and load resistance. In addition, when power is transmitted into the chamber by multiple shafts, the moment of inertia and torsional rigidity of each axis increase, making it difficult to drive in a balanced manner, and the use of a long shaft includes mechanical spring elements. There is also a problem that precise positioning becomes difficult. Furthermore, in the case of the multi-shaft type as shown in Patent Document 2, the volume and weight of the entire apparatus become large, and maintenance is difficult.

  In addition, bearings placed in an environment separated from the atmosphere side often use solid lubrication or special lubricants, and such bearings are often replaced because they have a shorter life than general bearings. There is a need. However, when a fixed ring of a bearing is arranged on a cup-shaped partition wall, it is necessary to remove the motor from the chamber when replacing one of the bearings, and the seal member is disassembled each time. A leak test or the like for confirming the sealing performance is necessary, and this is a cause of lowering the operating rate of the entire apparatus.

  The present invention has been made in view of the problems in the prior art, and can avoid the atmospheric contamination caused by the fixation of the magnetic poles while ensuring the rigidity necessary for the robot and is highly reliable. An object of the present invention is to provide a direct drive motor and a scalar robot used in the atmosphere of

The direct drive motor of the present invention is used in an atmosphere outside the atmosphere and is a three-axis coaxial direct drive motor in which three motors are arranged in series.
Each motor is a surface magnet type circumferentially opposed brushless motor,
Base,
A partition wall extending from the base and isolating the atmosphere side and the atmosphere outside;
A motor rotor disposed outside the atmosphere with respect to the partition;
A vacuum bearing device for rotatably supporting the motor rotor;
A stator facing the motor rotor and disposed on the atmosphere side with respect to the partition;
An atmosphere-side rotor that is arranged on the atmosphere side with respect to the partition wall and rotates together with the motor rotor, an angle detector that detects a rotation angle of the atmosphere-side rotor, and an atmosphere that rotatably supports the atmosphere-side rotor. A bearing device,
The atmosphere side rotor is supported by the atmosphere bearing device with respect to the base. The stator, the atmosphere bearing device, the atmosphere side rotor, the angle detector, and the motor rotor At least two of the vacuum bearing devices are arranged at positions where at least a part of the vacuum bearing devices overlap in the motor axial direction.

  According to the present invention, in at least one of the three-stage brushless motors connected in series, the stator, the atmospheric bearing device, the atmospheric rotor, the angle detector, and the motor rotor Since at least two of the vacuum bearing devices are arranged at positions where at least a part of the vacuum bearing devices overlap with each other in the motor axial direction, high rigidity can be ensured with a compact configuration.

For example, the first rotor is supported relative to the base via a first vacuum bearing device, and the second vacuum bearing device is supported with respect to the first motor rotor. The second motor rotor is supported so as to be relatively rotatable, and the third motor rotor is relatively rotatable with respect to the second motor rotor via a third vacuum bearing device. A direct drive motor supported by the motor can be considered. With this configuration, at least two of the stator, the atmospheric bearing device, the atmospheric rotor, the angle detector, the motor rotor, and the vacuum bearing device are used as motors. It can arrange | position in the position where at least one part superimposes mutually in an axial direction. The present invention having such characteristics has the following effects.
(1) It is not necessary to attach the stationary ring of the vacuum bearing device that supports the motor rotor to the partition wall, and mechanical rigidity can be improved. (2) By providing the vacuum bearing device outside the partition wall, Maintenance or the like of the vacuum bearing device can be performed without disassembling the sealing member between the sleeve and the partition wall.
(3) The direct drive eliminates the need for a multi-shaft structure as in the prior art, shortens the axial length, ensures high rigidity, and can set the inertia and torsional rigidity of each axis equally. Since there is no spring element, well-balanced and precise driving performance can be realized.
(4) By using a structure of position signal transmission by direct drive and magnetic coupling instead of a power transmission structure by multiple shaft structure and magnetic coupling, direct detection can be realized and robot positioning accuracy can be improved.

  In the radial direction of the triaxial coaxial direct drive motor, the vacuum bearing device, the motor rotor, the partition, the stator, the angle detector, and the atmosphere side rotation are sequentially performed from the outer peripheral side of each motor. It is preferable that the element and the atmosphere-side bearing device are arranged side by side.

In the radial direction of the three-axis coaxial direct drive motor, the stationary ring of the vacuum bearing device that rotatably supports the motor rotor of the first motor is fixed to a stationary member other than the partition wall,
A stationary ring of the vacuum bearing device that rotatably supports the motor rotor of a second motor adjacent to the first motor is fixed to the motor rotor of the first motor;
The stationary ring of the vacuum bearing device that rotatably supports the motor rotor of the third motor adjacent to the second motor is preferably fixed to the motor rotor of the second motor.

  The atmosphere-side rotor is rotatably supported by a bearing different from the vacuum bearing device, and has a magnetic pole or salient pole that faces the magnetic pole or salient pole attached to the motor rotor in the radial direction. It is preferable that the angle of the motor rotor is detected over the partition by the motor rotor and the atmosphere-side rotor being rotated by the magnetic attractive force of both magnetic poles.

  The angle detector preferably includes an absolute detector that detects an absolute angle and an incremental detector that detects a relative angle with high resolution.

  The scalar robot of the present invention uses the direct drive motor described above, and a first arm assembly that rotatably supports a first rotating ring is attached to the motor rotor of the first motor, and the third motor is mounted. A second arm assembly that rotatably supports the second rotating ring is fixed to the motor rotor of the second motor, and the motor rotor of the second motor is connected to the first rotating ring and the second rotating ring, respectively. Torque transmission is possible.

  The motor rotor of the second motor has one side race surface and the other side race surface divided in the axial direction of the motor, and the one side race surface is belted with respect to the first rotation ring, It is preferable that the other race surface is belted on the second rotating ring.

  The first arm assembly includes a first frame that rotatably supports the first rotating ring and is connected to a motor rotor of the first motor, and a first fixed ring fixed to the first frame. A first arm portion connected at one end to the first rotating ring, and a first arm portion rotatably supported on the other end side of the first arm portion and belted around the first fixed ring. It preferably has one terminal ring.

  The second arm assembly includes a second frame rotatably supporting the second rotating ring and connected to a motor rotor of the second motor, and a second fixed ring fixed to the second frame. A second arm portion having one end connected to the second rotating ring, a second arm portion rotatably supported on the other end side of the second arm portion, and a belt hooked to the second fixed ring. It preferably has a 2-terminal ring.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of a direct drive motor including a surface magnet type circumferentially opposed brushless motor according to the present embodiment.

In the present embodiment, a surface magnet type 20 pole 18 slot outer rotor brushless type direct drive motor is used. The slot combination of 20 poles and 18 slots has a configuration twice that of the slot combination of 10 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. Since the magnetic attractive force in the radial direction is canceled by increasing ²ⁿ times (n is an integer), vibration during rotation without increasing the roundness and coaxiality of the stator and 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 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. In addition, since the thickness and salient pole width of the stator connecting portion and the yoke thickness of the motor rotor can be reduced without reducing the total magnetic flux, a direct drive motor having a thin and large diameter and narrow width as in the present invention can be used. Is preferred.

  With reference to FIG. 1, the internal structure of a three-axis direct drive motor in which three brushless motors BM1 to BM3 are directly connected will be described in detail. A base 10 comprising a disk part 10a and a cylindrical part 10b connected to the outer edge of the disk part 10a is attached so that the periphery of the disk part 10a is installed on a surface plate (not shown). A plurality of circumferential grooves 10c are formed on the lower surface of the disk portion 10a, and a donut plate-shaped shielding plate 10d is attached by bolts B so as to shield the circumferential grooves 10c. A space surrounded by the plurality of circumferential grooves 10c and the shielding plate 10d is sealed with two O-rings OR, and coolant is injected into the space from the connector CN1 connected to the shielding plate 10d. The base 10 heated by the heat generated during operation is cooled. Note that the coolant that has undergone heat exchange is taken out from the connector CN2.

  A cylindrical first main body 12A is coaxially attached to the upper surface of the disk portion 10a of the base 10 by an inlay fit, and is fixed by a long bolt LB inserted from above. A cylindrical second main body 12B is coaxially attached to the upper surface of the first main body 12A by a spigot fitting and fixed by a long bolt LB inserted from above. Furthermore, on the upper surface of the second main body 12B, a cylindrical third main body 12C is coaxially attached by inlay fitting and fixed by a long bolt LB inserted from above. A disc 12D is coaxially attached to the upper surface of the third main body 12C by a spigot fitting and fixed with a bolt B.

  A thin cylindrical partition wall 13 has a lower end attached to the disk portion 10a of the base 10 and an upper end attached to the disc 12D. In addition, a through-hole is provided in the center of the main bodies 12A to 12C and can be used to pass wiring to the stator. The base 10, the main bodies 12 </ b> A to 12 </ b> C, and the disc 12 </ b> D constitute a housing.

  The partition wall 13 is made of stainless steel, which is a non-magnetic material, and includes a bottom portion 13a that spreads radially outward so as to face the disk portion 10a of the base 10, and brushless motors BM1, BM2, and BM3 extending axially from the inner peripheral edge thereof. It consists of a thin cylindrical portion 13b extending so as to penetrate and a flange-shaped attachment portion 13c extending radially inward from the upper edge of the cylindrical portion 13b. The inner edge of the attachment portion 13c is bent inward in the axial direction and extends a short distance.

  It is to be noted that a mouth flange portion can be fitted to the mouth of the partition wall 13. In such a case, the thin wall portion having substantially the same thickness as the cylindrical portion 13 b and the cylindrical portion 13 b are sealed and fixed by TIG welding in the axial direction. can do. In this way, by setting the welded portions to substantially the same thickness, it is possible to avoid heat from escaping only to the components on one side and to weld the fitting portions uniformly. It is preferable to apply a groove processing for fitting the sealing member to the collar portion of the mouth, and the fastening portion can be separated and separated from the atmosphere side by fastening the sealing member into the groove and then fastening to the flange with a screw.

  As is apparent, the partition wall 13 is commonly used for the brushless motors BM1, BM2, and BM3. A bottom portion 13a of the partition wall 13 is sandwiched between a disc portion 10a of the base 10 and an annular holding plate PT1 fitted to the inner periphery of the cylindrical portion 10b, and is fixed to the disc portion 10a using a bolt B. A space between the bottom portion 13a and the disk portion 10a is sealed with an O-ring OR. Further, the attachment portion 13c of the partition wall 13 is sandwiched between the disc 12D and the disc-like holding plate PT2, and is fixed to the disc 12D using a bolt B. A space between the mounting portion 13c and the disk 12D is sealed with an O-ring OR. As described above, the fastening portion of the partition wall 13 is separated and isolated from the atmosphere side. The partition wall 13 is made of austenitic stainless steel SUS316, which has high corrosion resistance and is particularly low in magnetism.

  Furthermore, since the base 10 and the surface plate are hermetically sealed, the internal space surrounded by the base 10 and the partition wall 13 is hermetically sealed from the outside (vacuum environment). 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 outer ring of a back combination angular contact ball bearing 19 used in vacuum is fitted to the inner peripheral step of the cylindrical portion 10b of the base 10 and is fixed by a hollow bolt B via an annular holding member PT3. ing. On the other hand, the inner ring of the back combination angular contact ball bearing 19 is fitted to the outer peripheral step portion of the yoke 21d of the first outer rotor member 21, and is pressed by the first cylindrical member 23 from above. A first cylindrical member 23 that supports a first arm assembly AA1, which will be described later, is made of an aluminum alloy having a small specific gravity as a metal material for reducing inertia, a fitting portion with an outer diameter portion of the yoke 21d, and a yoke It has a fastening part with the end face of 21d. The first cylindrical member 23 has a bearing holder portion for fitting and fixing the outer ring of the vacuum bearing device 19 'of the second brushless motor BM2 on the upper inner periphery. By adopting such a structure, it is not necessary to attach the stationary ring of the vacuum bearing device 19 'to the partition wall 12, and mechanical rigidity can be increased. The first outer rotor member 21 and the first cylindrical member 23 constitute a motor rotor.

  The base 10 is made of austenitic stainless steel having high corrosion resistance, and also serves as a fitting fixing and sealing device with a surface plate that is a chamber.

  The back combination angular contact ball bearing 19 (vacuum bearing device) can carry radial, axial and moment loads with a single bearing. By using this type of bearing, since only one bearing for supporting the rotor of the brushless motor BM1 is required, the triaxial coaxial direct drive motor of the present invention can be thinned. The back combination angular contact ball 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. Used.

  The back combination angular contact ball bearing 19 may be made by plating a soft metal such as gold or silver on the inner ring and the outer ring to obtain metal lubrication that does not release outgas even in a vacuum, or from an arm assembly described later. The first outer rotor member 21 can receive a moment in the tilting direction, but not limited to this, a cross roller, a cross ball, and a cross taper bearing can also be used. Fluorine-based coating treatment (DFO) may be performed for improvement.

  The first outer rotor member 21 includes a permanent magnet 21b and a vacuum coupling magnet 21c held by a magnet holder 21a, and an annular yoke 21d made of a magnetic material to form a magnetic path.

  The permanent magnet 21b is a segment type divided for each pole, and is made of a neodymium (Nd—Fe—B) magnet having a high energy product. This neodymium magnet has a very small coefficient of linear expansion compared with iron, and is also fragile and easily broken. In the present embodiment, a nickel coating having high corrosion resistance and high wear resistance is applied. By applying such a surface treatment, it is difficult to occlude impure molecules, and when it is fixed with a magnet holder 21a, which will be described later, dust generated due to sliding wear when exposed to extremely high or low temperatures. Therefore, it is suitable for a vacuum environment, and its individual shape is a substantially divided annular shape.

  The shape of the outer diameter side in contact with the yoke 21d of the permanent magnet 21b is an arc shape having the same radius or a slightly larger radius as the inner periphery of the yoke 21d described later. Further, the shape of the inner peripheral side which is the air gap side of the permanent magnet 21b is an arc shape having a radius such that the arc center of each permanent magnet 21b is the same as the rotation center when arranged on the yoke 21d. is there. Further, the shape of the circumferential end surface of the permanent magnet 21b is linear, and the circumferential end surface has a substantially trapezoidal shape in which the side facing the first stator 29 described later is narrow and the side in contact with the yoke 21d is wide. The direction end face is straight, but is perpendicular to the axis. Each side of the permanent magnet 21b is chamfered to prevent fine cracks and chips. The axial length is preferably set to be the same as or slightly longer than the first stator 29 to prevent torque shortage.

  On the other hand, the vacuum coupling magnet 21c is a type in which three poles (N—S—N or S—N—S) are magnetized on the surface of one magnet, and has a high energy product, neodymium (Nd—Fe—B). It is made of a system magnet. This neodymium magnet has a very small coefficient of linear expansion compared with iron, and is also fragile and easily broken. In the present embodiment, a nickel coating having high corrosion resistance and high wear resistance is applied. By applying such a surface treatment, it is difficult to occlude impure molecules, and when it is fixed by a magnet holder 21a, which will be described later, dust generated by sliding wear when exposed to extreme high temperatures or low humidity. This is suitable for a vacuum environment. Its individual shape is a substantially divided annular shape.

  The shape of the vacuum coupling magnet 21c on the outer diameter side in contact with the yoke 21d is an arc shape having the same radius or a slightly larger radius than the inner periphery of the yoke 21d described later. Further, the shape of the inner peripheral side that is the air gap side of the vacuum coupling magnet 21c is a circle having a radius such that the arc center of each permanent magnet 21b is the same as the center of rotation when arranged on the yoke 21d. It is arcuate. Furthermore, the shape of the circumferential end surface of the vacuum coupling magnet 21c is linear, and the circumferential end surface has a substantially trapezoidal shape where the side facing the atmospheric coupling magnet 30 described later is narrow and the side in contact with the yoke 21d is wide. Yes, the axial end face is straight but perpendicular to the axis. Each side of the vacuum coupling magnet 21c is chamfered to prevent fine cracks and chips. The length in the axial direction is preferably set to be the same as or slightly longer than the length of the atmospheric coupling magnet 30a described later to prevent torque shortage.

  FIG. 10 shows a perspective view of the magnet holder 21 a and the rotor holder 31. The magnet holder 21a is made of a non-magnetic material to prevent the magnetic flux from short-circuiting and reducing the flux linkage to the first stator 29, and prevents the permanent magnet 21b and the vacuum coupling magnet 21c from coming off the yoke 21d. It has a function. In particular, when non-magnetic stainless steel is used as this material, it has high corrosion resistance, so it is difficult to occlude impure molecules, and it is suitably used in a vacuum environment.

  On both end surfaces of the magnet holder 21a in the axial direction, fixing grooves (notches) 21x and 21y for the permanent magnet 21b and the vacuum coupling magnet 21c are evenly comb-like, and the outer diameter of the cylinder is the inner diameter of the yoke 21d. By the close fitting relationship, the permanent magnets 21b and the vacuum coupling magnets 21c can be arranged with high precision and evenness on the circumference, thereby obtaining the effect of reducing the coking torque and improving the magnetic coupling rigidity.

  The groove 21x for holding the permanent magnet 21b and the groove 21y for holding the vacuum coupling magnet 21c are independent of each other, and the permanent magnet 21b and the vacuum coupling magnet 21c can be set independently according to the required motor torque and the performance of the magnetic coupling. .

  The magnet holder 21a of the present embodiment includes 20 fixing grooves 21x for the permanent magnet 21b and 10 fixing grooves 21y for the vacuum coupling magnet 21c.

  One magnet piece fits into one groove 21x, 21y, the side surface of each groove 21x, 21y is substantially parallel to the axial direction, and the inclination of the side surface of the permanent magnet 21b and the vacuum coupling magnet 21c in the circumferential direction. The shape is parallel and has a gap. Further, even if the permanent magnet 21b and the vacuum coupling magnet 21c float in the air gap direction, this gap has a stronger attracting force with the yoke 21d than the attracting force with the first stator 29, and the use of the motor. It is a dimension in which a gap remains even when exposed to the low temperature side of the temperature and storage temperature.

  The yoke 21d is made of a low-carbon steel having high magnetism, and is plated with nickel in order to enhance rust prevention and corrosion resistance after processing and to prevent wear during bearing replacement. Its shape is substantially annular.

  In FIG. 1, a groove 21f for disposing a retaining ring 21e is provided at both ends in the inner diameter portion where the permanent magnet 21b and the vacuum coupling magnet 21c are disposed, and the distance between the retaining ring grooves 21f at both ends is the length of the permanent magnet 21b. + Slightly wider than the length of the spacer portion of the magnet holder 21a + the length of the vacuum coupling magnet 21c.

  The difference between the distance between the retaining ring grooves 21f at both ends and the length of the permanent magnet 21b + the length of the spacer portion of the magnet holder 21a + the length of the vacuum coupling magnet 21c was exposed to the low temperature side of the use temperature and storage temperature of the motor. It is a dimension in which a gap remains.

  On the outer diameter side of the yoke 21d, there is a step portion that is fitted and fixed to the inner ring of the back combination angular ball bearing 19, and has a structure of fitting with each other. In the case of the present embodiment, since the back-side combined angular contact ball bearing 19 of grease lubrication for vacuum is used, it is easy to obtain machining accuracy and the linear expansion coefficient is substantially the same as the bearing ring material of the bearing. By using an interference fit or intermediate fit with the yoke, the outer ring, which is a fixed ring, is a clearance fit with the cylindrical portion 10b of the base 10 made of aluminum or austenitic stainless steel that is frequently used in a vacuum environment. The angular contact ball bearing 19 is configured to prevent a decrease in rotational accuracy and an increase in friction torque due to a temperature increase.

  In the present embodiment, the permanent magnet 21b having a torque generating function and the vacuum coupling magnet 21c having a magnetic coupling attraction function are separated by a magnet holder 21a. However, the permanent magnet 21b and the vacuum coupling magnet 21c are separated from each other. It is not always necessary to separate them, and it is possible to combine the sources of torque generation and magnetic coupling attractive force into one magnet and fix them by an appropriate fixing method.

  After the permanent magnet 21b is assembled in the magnet holder 21d, in order to constrain the vertical movement of the permanent magnet 21b in the axial direction, double retaining rings 21e made of nonmagnetic stainless steel are provided on retaining ring grooves on both ends of the yoke 21d. In 21f, the permanent magnet 21b is fixed.

  The bolt (not shown) for fixing the magnet holder 21d is made of a low-carbon steel having high magnetism like the yoke 21d, and is nickel-plated to improve rust prevention and corrosion resistance after work forming and to prevent wear during bearing replacement. Has been given.

  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 the cylindrical outer peripheral portion of the flange portion 12a extending in the radial direction from the lower end of the first main body 12A, 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 fixed to the outer periphery of the rotor holder 31 and is rotatably supported via a ball bearing 33 with respect to the first main body 12A.

  The first inner rotor 30 is a plate-shaped member made of a permanent magnet 30a disposed in a recess formed at equal intervals on the outer periphery of the rotor holder 31, and a magnetic body mounted on the back surface of the permanent magnet 30a to form a magnetic path. Back yoke 30b. The permanent magnet 30a has a configuration of 30 poles, and 10 magnets of S pole-N pole-S pole or N pole-S pole-N pole are alternately made of magnetic metal. Accordingly, the first inner rotor 30 is rotated along with the first outer rotor member 21 driven by the first stator 29 by a magnetic coupling action. The back yoke 30b is made of a low-carbon steel having high magnetism, and is chromate plated for rust prevention after work forming.

  The shape of the outer peripheral side of the air gap side of the permanent magnet 30a is an arc shape having a radius slightly smaller than the inner diameter of the partition wall 13, and is parallel to the rotation axis in the axial direction. The shape of the permanent magnet 30a on the rotation axis center side is a plane, and is parallel to the rotation axis in the axial direction. The shape of the end face in the circumferential direction of the permanent magnet 30a is a straight line. The end face in the circumferential direction is a substantially trapezoidal shape that is narrow on the side facing the vacuum side and wide on the center side of the rotating shaft, and the end face in the axial direction is straight. , Perpendicular to the axis. Each side of the permanent magnet 30a is chamfered to prevent fine cracks and chips. The axial length is set to be almost the same as that of the atmosphere-side coupling magnet.

  As shown in FIG. 10, the rotor holder 31 has a fixed portion 31a of the permanent magnet 30a on the outer peripheral side along the circumferential direction, and each fixed portion 31a is arranged with the same number of poles as the permanent magnet 30a. ing. Each fixed portion is provided with a trapezoidal recess 31b that fits with the permanent magnet 30a. The side surface of each recess 31b is substantially parallel to the axial direction, and has a shape that is parallel and has a gap in the circumferential direction, following the inclination of the side surface of the permanent magnet 30a assembled here. In addition, even if the permanent magnet 30a floats in the air gap direction, this gap has a stronger attractive force with the yoke 21d than with the positioning key, and is further exposed to the low temperature side of the use temperature and storage temperature of the motor. It is a dimension in which a gap remains even when it is applied. In order to constrain the axial movement of the permanent magnet 30a, a highly reliable motor can be provided by fixing the permanent magnet 30a to the first inner rotor 30 using a two-component epoxy adhesive.

  In the motor axial direction, the center of the atmospheric-side permanent magnet 30a and the vacuum-side coupling magnet 21c are shifted from each other, whereby an axially downward attractive force can be applied to the permanent magnet 30a. An axial load is transmitted to the bearing device 33 via the rotor 30, and an appropriate preload effect can be provided. As a result, the rotation can be performed with high accuracy and the position can be detected accurately.

  The bearing 33 that rotatably supports the first inner rotor 30 is composed of two deep groove ball bearings that can apply radial, axial, and moment loads. 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 back yoke 30b is made of low carbon steel having high magnetism, and is chromate-plated for rust prevention after work forming.

  In FIG. 1, the inner periphery of the rotor holder 31 to which the first inner rotor 30 is attached is assembled to a rotating cylinder 34c that holds the resolver rotors 34a and 34b as a detector for measuring the rotation angle. A rotating cylinder 34 c that holds the inner periphery of the rotor holder 31 is rotatably supported by a bearing 33. The resolver stators 35 and 36 are attached to the outer periphery of the first main body 12A so as to face the resolver rotors 34a and 34b. In the present embodiment, the high-resolution incremental resolver stator 35 and any one rotation An absolute resolver stator 36 that can detect whether the rotor is in position is arranged in two layers. In this way, based on the absolute angle information from the absolute resolver, the rotor machine angle is recognized immediately after the power is turned on and the motor coil is commutated. On the other hand, high-resolution angle positioning is performed based on relative angle information from the incremental resolver. 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 angle used for driving current control of the brushless motor BM1. Detection is possible without using a pole detection sensor. Therefore, it is suitable for a direct drive motor that drives a scalar robot as in this embodiment.

  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 has a rotation shaft and a rotating shaft. 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 supported by the bearing 33, the reluctance between the magnetic poles of the incremental resolver stator 35 changes, and the fundamental wave of the reluctance change by one rotation of the incremental resolver rotor 34a. The reluctance change is detected so that the component has n cycles, and is digitized by the resolver control circuit shown in FIG. 2 and used as a position signal to rotate the incremental resolver rotor 34a, that is, the first inner rotor 30. An angle (or rotational speed) is 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 brushless motor BM2 will be described. Here, the second main body 12B constitutes a housing. The first cylindrical member 23, which is a part of the brushless motor BM1 described above, extends upward to the vicinity of the upper end of the brushless motor BM2, and has a double-row back combination used in a vacuum at its inner peripheral step. The outer ring of the angular ball bearing 19 ′ is fitted in a fitting manner, and is fixed by a hollow bolt B via an annular holding member PT4. On the other hand, the inner ring of the back combination angular ball bearing 19 'is fitted to the outer peripheral step portion of the yoke 21d' of the second outer rotor member 21 'and is pressed from above by the second cylindrical member 23'. The lower end of the second cylindrical member 23 ′ has a double cylindrical shape, and the upper end of the first cylindrical member 23 enters between them. Further, on the outer periphery of the second cylindrical member 23 ', a first race surface 23a' around which an eleventh belt BL11 (described later) is wound and a first race surface 23b 'around which the twenty-first belt BL21 is wound are separated in the axial direction. Is provided. In order to reduce inertia, the second cylindrical member 23 ′ is made of an aluminum alloy having a small specific gravity as a metal material, and a fastening portion between the fitting portion with the outer diameter portion of the yoke 21d ′ and the end surface of the yoke 21d ′. have. The second outer rotor member 21 ′ is integrally supported with the second cylindrical member 23 ′ so as to be rotatable with respect to the partition wall 13. The second outer rotor member 21 'constitutes the outer rotor.

  The back combination angular contact ball bearing 19 '(vacuum bearing device) can carry radial, axial and moment loads with a single bearing. By using this type of bearing, only one bearing for supporting the rotor of the brushless motor BM2 is required, so that the triaxial coaxial direct drive motor of the present invention can be made thinner. The back combined angular contact ball 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 element is a ceramic ball, and the lubricant is vacuum grease that does not solidify even under vacuum. Is used.

  The back combination angular contact ball bearing 19 'may be made by plating a soft metal such as gold or silver on the inner ring and the outer ring to obtain metal lubrication that does not release outgas even in a vacuum, or from an arm assembly described later. The second outer rotor member 21 ′ can receive a moment in the tilting direction, but is not limited to this, 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.

  The second outer rotor member 21 ′ is composed of a permanent magnet 21b ′ and a vacuum coupling magnet 21c ′ held by a magnet holder 21a ′, and an annular yoke 21d ′ made of a magnetic material to form a magnetic path. ing.

  The permanent magnet 21b 'is a segment type divided for each pole, and is made of a neodymium (Nd-Fe-B) magnet having a high energy product. This neodymium magnet has a very small coefficient of linear expansion compared with iron, and is also fragile and easily broken. In the present embodiment, a nickel coating having high corrosion resistance and high wear resistance is applied. By applying such a surface treatment, it is difficult to occlude impure molecules, and it is caused by sliding when fixed by a magnet holder 21a ′ described later, or by sliding wear when exposed to extremely high or low temperatures. Since it can prevent dust, it is suitable for a vacuum environment. Its individual shape is a substantially divided annular shape.

  The shape of the permanent magnet 21b 'on the outer diameter side in contact with the yoke 21d' is an arc shape having the same radius or a slightly larger radius than the inner periphery of the yoke 21d 'described later. Further, the shape of the inner peripheral side that is the air gap side of the permanent magnet 21b ′ has a radius such that the arc center of each permanent magnet 21b ′ is the same as the center of rotation when arranged on the yoke 21d ′. It is arcuate. Furthermore, the shape of the circumferential end surface of the permanent magnet 21b ′ is linear, and the circumferential end surface has a substantially trapezoidal shape where the side facing a second stator 29 ′, which will be described later, is narrow and the side contacting the yoke 21d ′ is wide. Yes, the axial end face is straight but perpendicular to the axis. Each side of the permanent magnet 21b 'is chamfered to prevent fine cracks and chips. The length in the axial direction is preferably set to be the same as or slightly longer than the length of the second stator 29 'to prevent torque shortage.

  On the other hand, the vacuum coupling magnet 21c ′ is a type in which three poles (N—S—N or S—N—S) are magnetized on the surface of one magnet, and has a high energy product, neodymium (Nd—Fe—B). ) Made of system magnets. This neodymium magnet has a very small coefficient of linear expansion compared with iron, and is also fragile and easily broken. In the present embodiment, a nickel coating having high corrosion resistance and high wear resistance is applied. By applying such a surface treatment, it is difficult to occlude impure molecules, and it is caused by sliding at the time of fixing with a magnet holder 21a ′, which will be described later, or by sliding wear when exposed to extreme high temperatures or low humidity. Since dust can be prevented, it is suitable for a vacuum environment. Its individual shape is a substantially divided annular shape.

  The shape of the outer diameter side of the vacuum coupling magnet 21c 'in contact with the yoke 21d' is an arc shape having the same radius or a slightly larger radius than the inner periphery of the yoke 21d 'described later. Further, the shape of the inner peripheral side that is the air gap side of the vacuum coupling magnet 21c ′ is such that the arc center of each permanent magnet 21b ′ becomes the same as the center of rotation when arranged on the yoke 21d ′. It is circular arc shape having. Furthermore, the shape of the circumferential end face of the vacuum coupling magnet 21c ′ is linear, and the side facing the atmospheric coupling magnet 30 ′, which will be described later, is narrow and the side in contact with the yoke 21d ′ is wide on the circumferential end face. It is trapezoidal, and its axial end face is straight, but is perpendicular to the axis. Each side of the vacuum coupling magnet 21c 'is chamfered to prevent fine cracks and chips. The length in the axial direction is preferably set to be the same as or slightly longer than the length of the atmospheric coupling magnet 30a 'described later to prevent torque shortage.

  The magnet holder 21a ′ is made of a non-magnetic material to prevent the magnetic flux from short-circuiting and reducing the flux linkage to the second stator 29 ′, and the permanent magnet 21b ′ and the vacuum coupling magnet 21c ′ are connected to the yoke 21d. It has a function to prevent it from coming off. In particular, when non-magnetic stainless steel is used as this material, it has high corrosion resistance, so it is difficult to occlude impure molecules, and it is suitably used in a vacuum environment.

  Similar to the one shown in FIG. 10, the fixing grooves (notches) for the permanent magnet 21b ′ and the vacuum coupling magnet 21c ′ are equally formed in comb teeth on both end faces of the magnet holder 21a ′ in the axial direction. Since the outer diameter of the cylinder has an interference fit with the inner diameter of the yoke 21d ', the permanent magnet 21b' and the vacuum coupling magnet 21c 'can be arranged accurately and evenly on the circumference, thereby reducing the coking torque. And an effect of improving the magnetic coupling rigidity.

  The groove for holding the permanent magnet 21b ′ and the groove for holding the vacuum coupling magnet 21c ′ are independent of each other, and the permanent magnet 21b ′ and the vacuum coupling magnet 21c ′ are independently set according to the required motor torque and the performance of the magnetic coupling. Can be set.

  The magnet holder 21a 'according to the present embodiment includes 20 fixing grooves for the permanent magnet 21b' and 10 fixing grooves for the vacuum coupling magnet 21c '.

  One magnet piece fits into one groove, the side surface of each groove is substantially parallel to the axial direction, and follows the inclination of the side surfaces of the permanent magnet 21b ′ and the vacuum coupling magnet 21c ′ in the circumferential direction, The shape is parallel and has a gap. Further, even if the permanent magnet 21b ′ and the vacuum coupling magnet 21c ′ float in the air gap direction, this gap has a stronger attracting force with the yoke 21d ′ than with the attracting force with the second stator 29 ′. It is a dimension in which a gap remains even when exposed to the low temperature side of the use temperature and storage temperature of the motor.

  The yoke 21d 'is made of low-carbon steel having high magnetism, and is plated with nickel in order to improve rust prevention and corrosion resistance after work forming and to prevent wear during bearing replacement. Its shape is substantially annular.

  Grooves 21f 'for disposing retaining rings 21e' are provided at both ends in the inner diameter portion where the permanent magnet 21b 'and the vacuum coupling magnet 21c' are disposed, and the distance between the retaining ring grooves 21f 'at both ends is determined by the permanent magnet 21b'. It is slightly wider than the length + the length of the spacer portion of the magnet holder 21a ′ + the length of the vacuum coupling magnet 21c ′.

  The difference between the distance between the retaining ring grooves 21f ′ at both ends and the length of the permanent magnet 21b ′ + the length of the spacer portion of the magnet holder 21a ′ + the length of the vacuum coupling magnet 21c ′ is the low temperature side of the motor operating temperature and storage temperature. It is a dimension in which a gap remains even when exposed to.

  On the outer diameter side of the yoke 21d ', there is a step portion that is fitted and fixed to the inner ring of the back combination angular ball bearing 19', and is structured to be fitted to each other. In the case of the present embodiment, since the back-side combined angular contact ball bearing 19 ′ of grease lubrication for vacuum is used, the inner ring can be easily processed with high accuracy and the linear expansion coefficient is substantially the same as the bearing ring material of the bearing. By using an interference fit or an intermediate fit with respect to the outer ring, the outer ring is a loose fit with respect to the first cylindrical member 23, thereby preventing a decrease in rotational accuracy of the back combination angular contact ball bearing 19 'and an increase in friction torque due to a temperature rise. It has a configuration.

  In the present embodiment, the permanent magnet 21b ′ having a torque generation function and the vacuum coupling magnet 21c ′ having a magnetic coupling attraction function are separated by a magnet holder 21a ′, but the permanent magnet 21b ′ and the vacuum cup are separated. It is not always necessary to separate the ring magnet 21c ′, and the sources of torque generation and magnetic coupling attractive force can be combined into one magnet and fixed by an appropriate fixing method.

  After the permanent magnet 21b ′ is installed in the magnet holder 21d ′, in order to restrain the vertical movement of the permanent magnet 21b ′ in the axial direction, double retaining rings 21e ′ made of nonmagnetic stainless steel are provided at both ends of the yoke 21d ′. The permanent magnet 21b 'is fixed in a certain retaining ring groove 21f'.

  The bolt (not shown) for fixing the magnet holder 21d ′ is made of a low-carbon steel having high magnetism like the yoke 21d ′, to improve rust prevention and corrosion resistance after processing and to prevent wear during bearing replacement. Nickel plating is applied.

  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 cylindrical outer peripheral portion of the flange portion 12 b extending in the radial direction from the lower end of the second main body 12 B, is formed of a laminated material of electromagnetic steel plates, and each salient pole is insulated. After the bobbin is fitted, the motor coil is concentratedly wound. 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 adjacent to and parallel to the second stator 29'. The second inner rotor 30 ′ is fixed to the outer periphery of the rotor holder 31 ′ and is rotatably supported by the second main body 12 </ b> B via a ball bearing 33 ′.

  The second inner rotor 30 ′ includes a permanent magnet 30a ′ disposed in a recess formed at equal intervals on the outer periphery of the rotor holder 31 ′, and a magnetic body that is mounted on the back surface of the permanent magnet 30a ′ to form a magnetic path. And a plate-like back yoke 30b ′. The permanent magnet 30a 'has a configuration of 30 poles, and each of 10 magnets of S poles-N poles-S poles or N poles-S poles-N poles is made of a magnetic metal alternately. Therefore, the second inner rotor 30 'is rotated in synchronism with the second outer rotor member 21' driven by the second stator 29 'by a magnetic coupling action. The back yoke 30b 'is made of low carbon steel having high magnetism, and is chromate plated for rust prevention after work forming.

  The shape of the outer peripheral side of the air gap side of the permanent magnet 30a 'is an arc shape having a radius slightly smaller than the inner diameter of the partition wall 13, and is parallel to the rotation axis in the axial direction. The shape of the permanent magnet 30a 'on the rotation axis center side is a plane, and is parallel to the rotation axis in the axial direction. The shape of the end face in the circumferential direction of the permanent magnet 30a 'is a straight line, and the end face in the circumferential direction is a substantially trapezoidal shape in which the side facing the vacuum side is narrow, the center side of the rotating shaft is wide, and the end face in the axial direction is straight. Is perpendicular to the axis. Each side of the permanent magnet 30a 'is chamfered to prevent fine cracks and chips. The axial length is set to be almost the same as that of the atmosphere-side coupling magnet.

  Referring to FIG. 10, the rotor holder 31 ′ has a fixed portion of the permanent magnet 30 a ′ on the outer peripheral side along the circumferential direction like a flower shape, and each fixed portion has the same number of poles as the permanent magnet 30 a ′. Is arranged in. Each fixed portion is provided with a trapezoidal recess that fits with the permanent magnet 30a '. The side surface of each recess is substantially parallel to the axial direction, and has a shape that is parallel and has a gap in the circumferential direction, following the inclination of the side surface of the permanent magnet 30a 'assembled therein. Further, even if the permanent magnet 30a 'floats in the air gap direction, this gap has a stronger attracting force with the yoke 21d' than the attracting force with the positioning key, and the motor operating temperature and storage temperature are lower. It is a dimension in which a gap remains even when exposed to. In order to restrain the axial movement of the permanent magnet 30a ′, a highly reliable motor can be provided by fixing the permanent magnet 30a ′ to the second inner rotor 30 ′ using a two-component epoxy adhesive. .

  In the motor axial direction, by placing the center of the atmospheric permanent magnet 30a ′ and the vacuum coupling magnet 21c ′ in a shifted position, it is possible to apply an axially downward attractive force to the permanent magnet 30a ′. An axial load is transmitted to the bearing device 33 ′ via the second inner rotor 30 ′, and an appropriate preload effect can be provided. As a result, the rotation can be performed with high accuracy and the position can be detected accurately.

  The bearing 33 ′ that rotatably supports the second inner rotor 30 ′ is composed of two deep groove ball bearings that can load radial, axial, and moment loads. 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 back yoke 30b 'is made of low carbon steel having high magnetism, and is chromate plated for rust prevention after work forming.

  In FIG. 1, the inner circumference of the rotor holder 31 ′ to which the second inner rotor 30 ′ is attached is assembled to a rotating cylinder 34c ′ that holds the resolver rotors 34a ′ and 34b ′ as a detector for measuring the rotation angle. ing. A rotating cylinder 34c 'that holds the inner periphery of the rotor holder 31' is rotatably supported by a bearing 33 '. Resolver stators 35 'and 36' are attached to the outer periphery of the second main body 12B so as to face the resolver rotors 34a 'and 34b'. In the present embodiment, a high resolution incremental resolver stator 35 ', An absolute resolver stator 36 'capable of detecting which position of the rotor is located in one rotation is arranged in two layers. In this way, based on the absolute angle information from the absolute resolver, the rotor machine angle is recognized immediately after the power is turned on and the motor coil is commutated. On the other hand, high-resolution angle positioning is performed based on relative angle information from the incremental resolver. 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 brushless motor BM2 Angle detection is possible without using a pole detection sensor. Therefore, it is suitable for a direct drive motor that drives a scalar robot as in this embodiment.

  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 second inner rotor 30 ′ supported by the bearing 33 ′, the reluctance with the magnetic pole of the incremental resolver stator 35 ′ changes, and the incremental resolver rotor 34a ′ rotates once. The reluctance change is detected so that the fundamental wave component of the reluctance change becomes n periods, digitized by the resolver control circuit shown in FIG. 2 as an example, and used as a position signal, so that the incremental resolver rotor 34a ′, that is, the first 2 The rotation angle (or rotation speed) of the inner rotor 30 ′ is detected. The resolver rotors 34a 'and 34b' and the resolver stators 35 'and 36' constitute a detector.

  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.

  Next, the brushless motor BM3 will be described. Here, the third main body 12C constitutes a housing. The second cylindrical member 23 ′, which is a part of the brushless motor BM 2 described above, extends upward to the upper end of the brushless motor BM 3, and has a double-row back combination used in a vacuum at its inner peripheral step. The outer ring of the angular ball bearing 19 ″ is fitted in a fitting manner and is fixed by a bolt (not shown) via an annular holding member PT5. On the other hand, the inner ring of the back combination angular ball bearing 19 ″ is a third outer rotor. The member 21 ″ is fitted to the outer peripheral step portion of the yoke 21d ″ and is pressed from above by the third cylindrical member 23 ″. The third outer rotor member 21 ″ is connected to the third cylindrical member 23 ″. It is integrally supported so as to be rotatable with respect to the partition wall 13. A third cylindrical member 23 ″ for supporting a second arm assembly AA2, which will be described later, has a low specific gravity as a metal material in order to reduce inertia. The iodonium alloy as a material, has "a fitting portion between the outer diameter portion of the yoke 21d" yoke 21d fastening portion of the end face of the. The third outer rotor member 21 ″ is supported integrally with the third cylindrical member 23 ″ so as to be rotatable with respect to the partition wall 13. The third outer rotor member 21 "and the third cylindrical member 23" constitute a motor rotor.

  The back combination angular contact ball bearing 19 "(vacuum bearing device) can carry radial, axial and moment loads with a single bearing. By using this type of bearing, one bearing for supporting the rotor of the brushless motor BM3 is provided. The three-axis coaxial direct drive motor of the present invention can be made thinner. The back combined angular contact ball bearing 19 "is made of martensitic stainless steel that has high corrosion resistance for both the inner and outer rings and can be hardened by quenching. Uses ceramic balls, and the lubricant is vacuum grease that does not solidify even under vacuum.

  The back combination angular contact ball 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 so as not to release outgas even in a vacuum, or from an arm assembly described later. The third outer rotor member 21 ″ can receive a moment in a tilting direction, but is not limited thereto, 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.

  The third outer rotor member 21 ″ includes a permanent magnet 21b ″ and a vacuum coupling magnet 21c ″ held by a magnet holder 21a ″, and an annular yoke 21d ″ made of a magnetic material to form a magnetic path. ing.

  The permanent magnet 21b ″ is a segment type divided for each pole, and is made of a neodymium (Nd—Fe—B) type magnet having a high energy product. This neodymium type magnet has a linear expansion coefficient as compared with iron. In this embodiment, it has a nickel coating that has high corrosion resistance and high wear resistance. It is suitable for a vacuum environment because it is difficult to occlude, and it can prevent sliding when fixed with a magnet holder 21a ″ described later, and dust generation due to sliding wear when exposed to extremely high or low temperatures. Each shape is a substantially divided annular shape.

  The shape of the permanent magnet 21b ″ on the outer diameter side in contact with the yoke 21d ″ is an arc shape having the same radius or a slightly larger radius than the inner periphery of the yoke 21d ″ described later. Further, on the air gap side of the permanent magnet 21b ″. The shape on the inner peripheral side is an arc shape having a radius such that the arc center of each permanent magnet 21b ″ is the same as the rotation center when arranged on the yoke 21d ″. Further, the shape of the end face in the circumferential direction of the permanent magnet 21b ″ is linear, and the end face in the circumferential direction has a substantially trapezoidal shape that is narrow on the side facing a third stator 29 ″ described later and wide on the side in contact with the yoke 21d ″. Yes, the end face in the axial direction is linear but perpendicular to the axis. Each side of the permanent magnet 21b "is chamfered to prevent fine cracks and chips. The length in the axial direction is preferably set to be the same as or slightly longer than the length of the third stator 29 ″ to prevent torque shortage.

  On the other hand, the vacuum coupling magnet 21c ″ is a type in which three poles (N—S—N or S—N—S) are magnetized on the surface of one magnet, and has a high energy product, neodymium (Nd—Fe—B). This neodymium magnet has a very low coefficient of linear expansion compared to iron, and is brittle and easy to crack.In this embodiment, it has improved corrosion resistance and is also resistant to abrasion. By applying such a surface treatment, impure molecules are hard to occlude, and slipping when fixing with a magnet holder 21a "described later, or at extremely high temperatures or low humidity It is suitable for a vacuum environment because it prevents dust generation due to sliding wear when exposed. Its individual shape is a substantially divided annular shape.

  The outer diameter side shape of the vacuum coupling magnet 21c ″ in contact with the yoke 21d ″ is an arc shape having the same radius or a slightly larger radius than the inner periphery of the yoke 21d ″ described later. The vacuum coupling magnet 21c ″ The shape of the inner peripheral side that is the air gap side is an arc shape having a radius such that the arc center of each permanent magnet 21b ″ is the same as the rotation center when arranged on the yoke 21d ″. Furthermore, the shape of the circumferential end face of the vacuum coupling magnet 21c ″ is a straight line, and the side facing the atmospheric coupling magnet 30 ″, which will be described later, is narrow and the side in contact with the yoke 21d ″ is wide on the circumferential end face. It has a trapezoidal shape, and its axial end face is straight but perpendicular to the axis. Each side of the vacuum coupling magnet 21c "is chamfered to prevent fine cracks and chips. . The length in the axial direction is preferably set to be the same as or slightly longer than the length of the atmospheric coupling magnet 30a ″ described later to prevent torque shortage.

  The magnet holder 21a "is made of a non-magnetic material to prevent the magnetic flux from short-circuiting and reducing the flux linkage to the third stator 29", and the permanent magnet 21b "and the vacuum coupling magnet 21c" are connected to the yoke 21d. In particular, when non-magnetic stainless steel is used as this material, it has high corrosion resistance and is difficult to occlude impure molecules, and thus is suitably used in a vacuum environment.

  Similarly to the one shown in FIG. 10, the fixing grooves (notches) for the permanent magnet 21b ″ and the vacuum coupling magnet 21c ″ are equally formed in comb teeth on both end faces of the magnet holder 21a ″ in the axial direction. Since the outer diameter of the cylinder has an interference fit with the inner diameter of the yoke 21d ″, the permanent magnet 21b ″ and the vacuum coupling magnet 21c ″ can be arranged accurately and evenly on the circumference, thereby reducing the coking torque. And an effect of improving the magnetic coupling rigidity.

  The groove for holding the permanent magnet 21b "and the groove for holding the vacuum coupling magnet 21c" are independent of each other, and the permanent magnet 21b "and the vacuum coupling magnet 21c" are independently set according to the required motor torque and the performance of the magnetic coupling. Can be set.

  The magnet holder 21a "of the present embodiment includes 20 fixing grooves for the permanent magnet 21b" and 10 fixing grooves for the vacuum coupling magnet 21c ".

  One magnet piece fits into one groove, the side surface of each groove is substantially parallel to the axial direction, and follows the inclination of the side surfaces of the permanent magnet 21b ″ and the vacuum coupling magnet 21c ″ in the circumferential direction, The shape is parallel and has a gap. Further, even if the permanent magnet 21b ″ and the vacuum coupling magnet 21c ″ float in the air gap direction, this gap has a stronger attracting force with the yoke 21d ″ than with the attracting force with the third stator 29 ″. It is a dimension in which a gap remains even when exposed to the low temperature side of the use temperature and storage temperature of the motor.

  The yoke 21d ″ is made of a low-carbon steel having high magnetism and is plated with nickel in order to improve rust prevention and corrosion resistance after work forming and to prevent wear during bearing replacement. The shape is substantially annular. .

  Grooves 21f "for disposing retaining rings 21e" are provided at both ends in the inner diameter portion where the permanent magnets 21b "and vacuum coupling magnets 21c" are disposed, and the distance between the retaining ring grooves 21f "at both ends is determined by the permanent magnet 21b". It is slightly wider than the length + the length of the spacer portion of the magnet holder 21a "+ the length of the vacuum coupling magnet 21c".

  The difference between the distance between the retaining ring grooves 21f "at both ends and the length of the permanent magnet 21b" + the length of the spacer portion of the magnet holder 21a "+ the length of the vacuum coupling magnet 21c" is the lower temperature side of the operating temperature and storage temperature of the motor. It is a dimension in which a gap remains even when exposed to.

  On the outer diameter side of the yoke 21d ″, there is a step portion that is fitted and fixed to the inner ring of the back combination angular ball bearing 19 ″, and is structured to be fitted to each other. In the case of the present embodiment, a back greased ball bearing 19 ″ with vacuum grease lubrication is used, so that the inner ring can be easily processed with high accuracy and the linear expansion coefficient is substantially the same as the bearing ring material of the bearing. By using an interference fit or an intermediate fit with respect to the outer ring, the outer ring is a loose fit with respect to the first cylindrical member 23, thereby preventing a decrease in rotational accuracy of the back combination angular contact ball bearing 19 "and an increase in friction torque due to a temperature rise. It has a configuration.

  In the present embodiment, the permanent magnet 21b ″ having a torque generating function and the vacuum coupling magnet 21c ″ having a magnetic coupling attraction function are separated by a magnet holder 21a ″. However, the permanent magnet 21b ″ and the vacuum cup are separated. The ring magnet 21c ″ does not necessarily need to be separated, and the sources of torque generation and magnetic coupling attractive force can be combined into one magnet and fixed by an appropriate fixing method.

  After the permanent magnet 21b "is installed in the magnet holder 21d", in order to restrain the vertical movement of the permanent magnet 21b "in the axial direction, double retaining rings 21e" made of nonmagnetic stainless steel are provided at both ends of the yoke 21d ". The permanent magnet 21b "is fixed in a certain retaining ring groove 21f".

  The bolt (not shown) for fixing the magnet holder 21d ″ is made of a low-carbon steel having high magnetism like the yoke 21d ″, to increase rust prevention and corrosion resistance after processing and to prevent wear during bearing replacement. Nickel plating is applied.

  A third 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 third outer rotor member 21 ″. The third stator 29 ″ is attached to the cylindrical outer peripheral portion of the flange portion 12c extending in the radial direction from the lower end of the third main body 12C, is formed of a laminated material of electromagnetic steel plates, and each salient pole is insulated. After the bobbin is fitted, the motor coil is concentratedly wound. The outer diameter of the third stator 29 "is substantially the same as or smaller than the inner diameter of the partition wall 13.

  A third inner rotor 30 ″ is disposed adjacent to and parallel to the third stator 29 ″. The third inner rotor 30 ″ is fixed to the outer periphery of the rotor holder 31 ″ and is rotatably supported by the third main body 12C via ball bearings 33 ″.

  The third inner rotor 30 ″ includes a permanent magnet 30a ″ disposed in a recess formed at equal intervals on the outer periphery of the rotor holder 31 ″, and a magnetic body mounted on the back surface of the permanent magnet 30a ″ to form a magnetic path. The permanent magnet 30a ″ is composed of 30 poles, and 10 magnets of S pole-N pole-S pole or N pole-S pole-N pole are alternately magnetized. Made of metal. Accordingly, the third inner rotor 30 ″ is rotated in synchronism with the third outer rotor member 21 ″ driven by the third stator 29 ″ by the magnetic coupling action. The back yoke 30b ″. Is made of low-carbon steel with high magnetism, and is chromate-plated for rust prevention after machining.

  The shape of the outer peripheral side of the air gap side of the permanent magnet 30a ″ is an arc shape having a radius slightly smaller than the inner diameter of the partition wall 13. In the axial direction, the shape is parallel to the rotation axis. The rotation magnet center side of the permanent magnet 30a ″ The shape is a plane, and is parallel to the rotation axis in the axial direction. The shape of the end face in the circumferential direction of the permanent magnet 30a ″ is linear, and the end face in the circumferential direction has a substantially trapezoidal shape in which the side facing the vacuum side is narrow and the center side of the rotating shaft is wide, and the axial end face is linear. However, each side of the permanent magnet 30a ″ is chamfered to prevent fine cracks and chips. The axial length is set to be almost the same as that of the atmosphere-side coupling magnet.

  Referring to FIG. 10, the rotor holder 31 ″ has a fixed portion of the permanent magnet 30a ″ on the outer peripheral side along the circumferential direction, like a flower shape, and each fixed portion has the same number of poles as the permanent magnet 30a ″. Each fixed portion is provided with a trapezoidal recess that fits with the permanent magnet 30a ″. The side surface of each recess is substantially parallel to the axial direction, and has a shape that is parallel and has a gap in the circumferential direction, following the inclination of the side surface of the permanent magnet 30a ″ assembled here. This gap is permanent. Even if the magnet 30a ″ floats in the air gap direction, the attracting force with the yoke 21d ″ is stronger than the attracting force with the positioning key, and even when exposed to the low temperature side of the use temperature and storage temperature of the motor. This is a dimension in which the gap remains. In order to constrain the axial movement of the permanent magnet 30a ″, the permanent magnet 30a ″ is fixed to the third inner rotor 30 ″ by using a two-component epoxy adhesive, thereby achieving high reliability. The motor can be provided.

  In the motor axial direction, by disposing the center of the atmospheric-side permanent magnet 30a ″ and the vacuum-side coupling magnet 21c ″ in a shifted manner, it is possible to apply an axially downward attractive force to the permanent magnet 30a ″. An axial load is transmitted to the bearing device 33 ″ through the third inner rotor 30 ″, and an appropriate preload effect can be provided. Thereby, high-precision rotation can be performed and accurate position detection can be performed.

  The bearing 33 ″ that rotatably supports the third inner rotor 30 ″ is composed of two deep groove ball bearings that can apply radial, axial, and moment loads. 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 high energy product neodymium (Nd-Fe-B) magnet and is coated with nickel to prevent demagnetization due to rust. The back yoke 30b" is made of low carbon steel having high magnetism. And chromate plating for rust prevention after processing and molding.

  In FIG. 1, the inner circumference of the rotor holder 31 ″ with the third inner rotor 30 ″ attached thereto is assembled as a detector for measuring the rotation angle into a rotating cylinder 34c ″ that holds the resolver rotors 34a ″ and 34b ″. The rotating cylinder 34c ″ that holds the inner periphery of the rotor holder 31 ″ is rotatably supported by a bearing 33 ″. Resolver stators 35 ″, 36 ″ are attached to the outer periphery of the third main body 12C so as to face the resolver rotors 34a ″ and 34b ″. In the present embodiment, a high resolution incremental resolver stator 35 ″, An absolute resolver stator 36 "capable of detecting at which position of one rotation the rotor is arranged in two layers. In this way, based on the absolute angle information from the absolute resolver, the rotor machine angle is recognized immediately after the power is turned on and the motor coil is commutated. On the other hand, high-resolution angle positioning is performed based on relative angle information from the incremental resolver. 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 controlling the drive current of the brushless motor BM3. Angle detection is possible without using a pole detection sensor, which is suitable for a direct drive motor that drives a scalar robot as in this embodiment.

  An outer boss that connects the rotation side of the angle detector, the rotation side of the bearing 33 "and the detector coupling, and an inner boss that connects the stationary side of the angle detector and the stationary side of the bearing device are used for the motor field and motor coil. In order to prevent electromagnetic noise from being transmitted to the resolver, which is a detector, carbon steel, which is a magnetic material, is used as a material, and chromate plating is applied to prevent rust after processing.

  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. Parallel to the axis, each magnetic pole is provided with teeth shifted in phase with respect to the incremental resolver rotor 34a ", and a coil is wound around each magnetic pole. A third inner rotor 30" supported by a bearing 33 ". When the incremental resolver rotor 34a "rotates together with the magnetic pole, 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 revolution of the incremental resolver rotor 34a ". Figure 2 shows the reluctance change detected. Digitized by a resolver control circuit shown, so as to detect the rotation angle of the incremental resolver rotor 34a by utilizing as a position signal "that is, the third inner rotor 30" (or rotational speed). The resolver rotors 34a "and 34b" and the resolver stators 35 "and 36" constitute a detector.

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

  In the radial direction of the three-axis coaxial direct drive motor of the present embodiment, the vacuum bearing devices 19, 19 ′, 19 ″ and the outer rotor members 21, 21 as motor rotors are sequentially arranged from the outer peripheral side of the brushless motors BM1 to BM3. ', 21 ", the partition wall 13, the stators 29, 29', 29", the angle detectors connected to the inner rotor members 30, 30 ', 30 "which are atmospheric side rotors, and the atmospheric side bearing device 33. , 33 ′, 33 ″, and at least two of them are arranged at positions where they are overlapped when viewed in the direction perpendicular to the axis.

  In the three-axis coaxial direct drive motor of the present embodiment, the stationary ring of the vacuum bearing device 19 of the first brushless motor BM1 is fixed to a stationary member other than the partition wall 13 (here, the cylindrical portion 10b of the base 10). The rotating wheel is fixed to the first cylindrical member 23. The outer ring of the vacuum bearing device 19 'of the second brushless motor BM2 is fixed to the first cylindrical member 23, and the inner ring is fixed to the second cylindrical member 23'. Further, the outer ring of the vacuum bearing device 19 ″ of the third brushless motor BM3 is fixed to the second cylindrical member 23 ′, and the inner ring is fixed to the third cylindrical member 23 ″.

  FIG. 3 is a block diagram showing a drive circuit for the brushless motors BM1 to BM3. When a motor rotation command is input from an external computer, the motor control circuit DMC1 for the brushless motor BM1, the motor control circuit DMC2 for the brushless motor BM2, and the motor control circuit DMC3 for the brushless motor BM3 are each 3 from the CPU. A drive signal is output to the layer amplifier (AMP), and a drive current is supplied from the three-layer amplifier (AMP) to the brushless motors BM1 to BM3. Thereby, the cylindrical members 23, 23 ′, 23 ″ of the brushless motors BM1 to BM3 rotate independently to move the arm assembly as will be described later. Cylindrical members 23, 23 ′, 23 "" Rotates, resolver signals are output from the resolver stators 35, 36, 35 ', 36', 35 ", 36" whose rotation angles have been detected as described above, and these are output to the resolver digital converter (RDC). The CPU that has been input after digital conversion determines whether or not the cylindrical members 23, 23 ′, 23 ″ have reached the command position. If the command position is reached, the drive signal to the three-layer amplifier (AMP) is determined. Is stopped, the rotation of the cylindrical members 23, 23 ′, 23 ″ is stopped. This enables servo control of the cylindrical members 23, 23 ', 23 ".

  Next, a scalar robot using the triaxial coaxial direct drive motor of the present embodiment will be described. 4 is a perspective view of a scalar robot using the triaxial coaxial direct drive motor of FIG. 1 as viewed from above, FIG. 5 is a perspective view as viewed from below, and FIG. 6 is a wafer support portion omitted. FIG. 7 is a front view of the scalar robot shown with the wafer support removed, and FIG. 8 is a cross-sectional view of the scalar robot shown with the wafer support removed. It is.

  In the figure, a first arm assembly AA1 is provided around a cylindrical member 23 connected to the motor rotor of the first brushless motor BM1. In the first arm assembly AA1, the first post FR11 is attached to the other end of the casing-like first frame FR1 that is bolted to the cylindrical member 23 at one end. A twelfth pulley (first stationary ring) PL12 is coaxially fixed to the upper end of the eleventh post PS11.

  Around the eleventh post PS11, the first hollow shaft HS1 is rotatably supported by the ball bearing BR. An eleventh pulley (first rotating ring) PL11 is connected to the lower end of the first hollow shaft HS1, and one end of the housing-like first arm portion AM1 is fixed to the upper end of the first hollow shaft HS1. ing. One end side of the first arm portion AM1 accommodates the twelfth pulley PL12, and the lower end side of the twelfth post PS12 is rotatably supported by the ball bearing BR at the other end. A thirteenth pulley (first end ring) PL13 is fixed to the upper end of the twelfth post PS12. A first claw member NL1 for holding a wafer or the like is attached to the upper surface of the thirteenth pulley PL13 so as to rotate integrally.

  An eleventh belt BL11 is stretched between the outer diameter portion of the eleventh pulley PL11 and the first race surface 23a ′ of the cylindrical member 23 ′, and both rotate in a predetermined relationship according to the outer diameter. It is like that. A twelfth belt BL12 is stretched between the outer diameter portion of the twelfth pulley PL12 and the outer diameter portion of the thirteenth pulley PL13 so that both rotate in a predetermined relationship according to the outer diameter. It has become.

  On the other hand, a second arm assembly AA2 is provided around a cylindrical member 23 ″ connected to the motor rotor of the third brushless motor BM2. A second arm assembly similar to the first arm assembly AA1 is provided. In the arm assembly AA2, a housing-like second frame FR2 bolted at one end to a cylindrical member 23 ″ has a 21st post PS21 attached at the other end. A 22nd pulley (first rotating ring) PL22 is coaxially fixed to the upper end of the 21st post PS21.

  Around the 21st post PS21, the second hollow shaft HS2 is rotatably supported by the ball bearing BR. A 21st pulley (second rotating ring) PL21 is connected to the lower end of the second hollow shaft HS2, and one end of the housing-like second arm portion AM2 is fixed to the upper end of the second hollow shaft HS2. ing. The one end side of the second arm portion AM2 accommodates the twenty-second pulley PL22, and the lower end side of the twenty-second post PS22 is rotatably supported by the ball bearing BR at the other end. A 23rd pulley (second end ring) PL23 is fixed to the upper end of the 22nd post PS22. A second claw member NL2 for holding a wafer or the like is attached to the upper surface of the 23rd pulley PL23 so as to rotate integrally. As shown in FIG. 8, in the height direction, the first arm portion AM1 has a dimension that allows entry between the second arm portion AM3 and the direct drive motor D.

  The 21st belt BL21 is stretched between the outer diameter portion of the 21st pulley PL21 and the second race surface 23b ′ of the cylindrical member 23 ′, and both rotate in a predetermined relationship according to the outer diameter. It is like that. The 22nd belt BL22 is stretched between the outer diameter portion of the 22nd pulley PL22 and the outer diameter portion of the 23rd pulley PL23 so that both rotate in a predetermined relationship according to the outer diameter. It has become.

  Next, the operation of the scalar robot will be described with reference to FIG. FIG. 9 is a view of the simplified first arm assembly AA1 as viewed in the axial direction of the motor, but the first arm portion is omitted for easy understanding, and the pulley diameter is different from the actual one. First, assuming that the first brushless motor BM2 is stationary and the first brushless motor BM1 is operated to rotate the first frame counterclockwise, the first post PS1 is rotated by the rotation of the first frame FR1. 9 moves around the rotation axis O of the motor as shown in FIG.

  However, since the second brushless motor BM2 is stationary, the rotation of the eleventh pulley PL11 connected by the second cylindrical member 23 'and the eleventh belt BL11 is restricted. Therefore, relative rotation occurs between the eleventh post PS11 and the first hollow shaft HS1, and thereby the first arm portion AM1 is angled with respect to the first frame FR1.

  At this time, the twelfth post PS12 attached to the first arm portion AM1 is also displaced, but the twelfth post PS12 is rotatably supported by the ball bearing BR, and the thirteenth pulley PL13 and the twelfth belt BL12 are connected. As a result, the rotation of the first claw member NL1 attached to the thirteenth pulley PL13 with respect to the original position relative to the rotation axis O of the motor is restricted. It will move linearly in the radial direction. That is, the first claw member NL1 is moved by a desired distance in the radial direction by stopping the second brushless motor BM2 and operating the first brushless motor BM1. The same applies to the reverse direction.

  On the other hand, since the second brushless motor BM2 is stopped and the third brushless motor BM3 is operated, the second claw member NL2 is similarly moved by a desired distance in the radial direction. The same applies to the reverse direction.

  Furthermore, by simultaneously operating the brushless motors BM1 to BM3 in the same direction at the same speed and the same angle, the arm assemblies AA1 and AA2 can be turned at any angle while maintaining the posture before turning. With the above combination, the claw members NL1 and NL2 can be independently displaced to the positions of arbitrary two-dimensional coordinates.

  According to the present embodiment, it is not necessary to attach the stationary ring of the bearing device that supports the motor rotor to the partition wall, and the mechanical rigidity can be increased. Further, the bearing can be replaced without disassembling the O-ring OR provided between the partition wall 13 and the base 10. Furthermore, because of the direct drive, a multi-shaft structure is unnecessary, and the inertia and torsional rigidity of each axis can be set to be approximately the same, so that a balanced drive performance can be realized. Direct detection can be realized and the robot positioning accuracy can be improved by using a structure of direct drive and position signal transmission by magnetic coupling instead of a power transmission structure by multiple shafts and magnetic coupling. In particular, the two arm portions can be independently driven by three motors, and the conveyance efficiency can be improved.

  As described above, in the present embodiment, the outer rotor type motor has been described as an example, but the same effect can be obtained by the inner rotor type. In that case, the tangent intersection of the end face of the permanent magnet and the yoke (magnet holder) should be at an angle that cannot float more than the gap with the yoke as in this embodiment. In order to prevent the permanent magnets from scattering, it is preferable to cover the motor rotor with a nonmagnetic thin tube. The permanent magnet has been described using a neodymium (Nd-Fe-B) -based magnet as an example of nickel coating as a coating for enhancing corrosion resistance, but is not limited to this material and surface treatment. The samarium-cobalt (Sm-Co) magnet, which is difficult to demagnetize at high temperature, should be used depending on the temperature conditions at the time of baking out. If used, 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 used in ultra-vacuum, Kanigen plating, clean s plating, titanium nitride coating, etc. with few pinholes should be applied.

  In addition, the vacuum bearing device has been described as an example using a vacuum grease lubricated back-combination angular contact ball bearing, but is not limited to this type, material, and lubrication method, and the environment used, load conditions, It is appropriately changed depending on the rotational speed, and may be a cross roller bearing, a deep groove ball bearing or a structure that applies preload as a four-point contact bearing, and when used in 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.

  Further, the material of the holder and the bolt is appropriately changed depending on the manufacturing cost and the environment in which it is used. Further, the motor rotor does not necessarily have to be an integral circle, and may have a divided configuration as long as the same function can be achieved. In this case, the material cost can be reduced.

  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 rotor, and 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.

  In addition, as an example of using a grease-lubricated deep groove ball bearing as the bearings 33 and 33 ″ for rotatably supporting the rotation side of the angle detector, the present invention is not limited to this type and lubrication method. If the multipoint contact bearing cannot be used for high speed rotation or reduction of friction torque, the angular bearing or deep groove ball bearing should be It is good also as a structure which arrange | positions to 2 and applies 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.

  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 scalar robot according to the present embodiment is not limited to a vacuum atmosphere, and can be used 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 sectional drawing of the direct drive motor containing the surface magnet type circumference facing brushless motor concerning this Embodiment. 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 the perspective view seen from the upper direction of the scalar robot using the 3-axis coaxial direct drive motor of FIG. It is the perspective view seen from the downward direction of the scalar robot using the 3-axis coaxial direct drive motor of FIG. It is a perspective view of the scalar robot shown in a state where the wafer support portion is deleted. It is a front view of the scalar robot shown in a state where the wafer support portion is deleted. It is sectional drawing of the scalar robot shown in the state which deleted the wafer support part. It is the figure which looked at simplified 1st arm assembly AA1 in the axial direction of the motor. 3 is a perspective view of a magnet holder 21a and a rotor holder 31. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Base 10a Disk part 10b Cylindrical part 10c Circumferential groove 10d Shielding board 12A 1st main body 12B 2nd main body 12C 3rd main body 12D Disc 12a Flange part 12b Flange part 12c Flange part 13 Partition 13a Bottom part 13b Cylindrical part 13c Attachment part 19, 19 ', 19 "angular contact ball bearings 21, 21', 21" outer rotor members 21a, 21a, 21a "magnet holders 21b, 21b ', 21b" permanent magnets 21c, 21c', 21c "vacuum side coupling magnets 21d, 21d ', 21d "Yoke 21e, 21e', 21e" Retaining ring 21f, 21f ', 21f "Retaining ring groove 23, 23', 23" Cylindrical member 23a 'First race surface 23b' Second race surface 29, 29 ', 29 "Stator 30, 30', 30" Inner rotor 30a, 30a ', 30a "Permanent magnet 30b, 30b ', 30B "Back yoke 31, 31', 31" Rotor holder 33, 33 ', 33 "Ball bearing 34a, 34a', 34a" Incremental resolver rotor 34b, 34b ', 34b "Absolute resolver rotor 34c, 34c' 34c "rotating cylinder 35, 35 ', 35" incremental resolver stator 36, 36', 36 "absolute resolver stator AA1 first arm assembly AA2 second arm assembly AM1 first arm part AM2 second arm part B bolt BL11 eleventh Belt BL12 12th belt BL21 21st belt BL22 22nd belt BM1 to BM3 Brushless motor BR Ball bearing CN1 Connector CN2 Connector D Direct drive motor DMC1 Motor control circuit DMC2 Motor control circuit MC3 Motor control circuit FR1 1st frame FR2 2nd frame HS1 1st hollow shaft HS2 2nd hollow shaft LB Long bolt NL1 1st claw member NL2 2nd claw member OR O-ring PL11 11th pulley PL12 12th pulley PL13 13th Pulley PL21 21st pulley PL22 22nd pulley PL23 23rd pulley PS11 11th post PS12 12th post PS21 21st post PS22 22nd post PT1 restraining plate PT2 restraining plate PT3 restraining member PT4 restraining member PT5 restraining member

Claims (9)

In a 3-axis coaxial direct drive motor that is used in an atmosphere outside the atmosphere and has three motors arranged in series,
Each motor is a surface magnet type circumferentially opposed brushless motor,
Base,
A partition wall extending from the base and isolating the atmosphere side and the atmosphere outside;
A motor rotor disposed outside the atmosphere with respect to the partition;
A vacuum bearing device for rotatably supporting the motor rotor;
A stator facing the motor rotor and disposed on the atmosphere side with respect to the partition;
An atmosphere-side rotor that is arranged on the atmosphere side with respect to the partition wall and rotates together with the motor rotor, an angle detector that detects a rotation angle of the atmosphere-side rotor, and an atmosphere that rotatably supports the atmosphere-side rotor. A bearing device,
The atmosphere side rotor is supported by the atmosphere bearing device with respect to the base. The stator, the atmosphere bearing device, the atmosphere side rotor, the angle detector, and the motor rotor The direct drive motor is characterized in that at least two of the vacuum bearing devices are arranged at positions where at least a part of the vacuum bearing devices overlap in the motor axial direction.   Angles connected to the vacuum bearing device, the motor rotor, the partition, the stator, and the atmosphere-side rotor in the radial direction of the triaxial coaxial direct drive motor in order from the outer peripheral side of each motor. The direct drive motor according to claim 1, wherein the detector and the atmosphere side bearing device are arranged side by side. Of the three-axis coaxial direct drive motor, the stationary wheel of the vacuum bearing device of the first motor is fixed to a stationary member other than the partition wall, and the rotating wheel is connected to the motor rotor of the first motor. Fixed,
One wheel of the vacuum bearing device of the second motor adjacent to the first motor is fixed to the motor rotor of the first motor, and the other wheel is fixed to the second motor. Fixed to the motor rotor,
One ring of the vacuum bearing device of the third motor adjacent to the second motor is fixed to the motor rotor of the second motor, and the other ring of the third motor The direct drive motor according to claim 1, wherein the direct drive motor is fixed to the motor rotor.   The atmosphere-side rotor is rotatably supported by a bearing different from the vacuum bearing device, and has a magnetic pole or salient pole that faces the magnetic pole or salient pole attached to the motor rotor in the radial direction. The angle of the motor rotor is detected over the partition by the motor rotor and the atmosphere-side rotor being rotated by the magnetic attractive force of both magnetic poles. The direct drive motor described in Crab.   5. The direct drive motor according to claim 1, wherein the angle detector includes an absolute detector that detects an absolute angle and an incremental detector that detects a relative angle with high resolution. 6.   6. The direct drive motor according to claim 1, wherein a first arm assembly that rotatably supports a first rotating ring is attached to a motor rotor of the first motor, A second arm assembly that rotatably supports a second rotary ring is fixed to the motor rotor of the motor of the second motor, and the motor rotor of the second motor is connected to the first rotary ring and the second rotary ring. Each is a scalar robot characterized by its ability to transmit torque.   The motor rotor of the second motor has one side race surface and the other side race surface divided in the axial direction of the motor, and the one side race surface is belted with respect to the first rotation ring, The scalar robot according to claim 6, wherein the other race surface is belted with respect to the second rotating ring.   The first arm assembly includes a first frame that rotatably supports the first rotating ring and is connected to a motor rotor of the first motor, and a first fixed ring fixed to the first frame. A first arm portion connected at one end to the first rotating ring, and a first arm portion rotatably supported on the other end side of the first arm portion and belted around the first fixed ring. The scalar robot according to claim 6, wherein the scalar robot has one end ring.   The second arm assembly includes a second frame rotatably supporting the second rotating ring and connected to a motor rotor of the second motor, and a second fixed ring fixed to the second frame. A second arm portion having one end connected to the second rotating ring, a second arm portion rotatably supported on the other end side of the second arm portion, and a belt hooked to the second fixed ring. The scalar robot according to claim 8, further comprising a two-terminal ring.

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