Motor

Abstract

To provide a motor which can inhibit emitted dust from flowing out to the outside.SOLUTION: A motor has: a housing including a housing base and a housing shaft part provided in the housing base and extending in a direction along a rotation center axis; a motor stator disposed in a radial outer side of the housing shaft part; a motor rotor provided between the motor stator and the housing shaft part; a bearing provided in a radial inner side of the motor rotor and rotatably supporting the motor rotor on the housing shaft part; a seal structure which is provided in a side opposite to the housing base in an axial direction of the motor rotor and seals a space between the motor rotor and the housing shaft part; and a resolver which detects rotation of the motor rotor. The resolver is provided in a radial outer side relative to the bearing and closer to a side opposite to the housing base than the motor stator in the axial direction when viewed in a direction along the rotation center axis. The resolver includes a differential type incremental resolver.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a motor. [Background technology]

[0002] Patent Documents 1 to 3 describe motors used in a vacuum atmosphere or the like. In the motors described in Patent Documents 1 to 3, a partition wall is provided between the motor rotor and the motor stator. The partition wall separates the space in which the motor rotor is disposed from the space in which the motor stator is disposed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2006-311649 A [Patent Document 2] Patent No. 4445075 [Patent Document 3] JP 2001-339920 A Summary of the Invention [Problem to be solved by the invention]

[0004] For example, in semiconductor manufacturing processes and the like, when a motor is used in a vacuum and high-temperature environment, it is required to suppress dust and gas generation from the motor. The motor described in Patent Document 1 is a so-called outer rotor type, and the motor rotor is installed on the vacuum atmosphere side (inside a chamber). For this reason, dust and gas generation from the motor rotor may flow into the vacuum atmosphere side. In addition, magnetic force (magnetic field) generated by the motor's drive current is radiated and propagated as noise, and when it reaches the resolver, which is an encoder, erroneous detection of position information may occur.

[0005] In the motors of Patent Documents 2 and 3, a bearing is provided on the outer periphery of the motor rotor or the output shaft connected to the motor rotor. For this reason, the bearing is exposed to the vacuum atmosphere, and there is a possibility that dust generated from the bearing will flow into the vacuum side.

[0006] The present invention has been made in consideration of the above-mentioned problems, and has an object to provide a motor that can suppress the outflow of dust to the outside. [Means for solving the problem]

[0007] In order to achieve the above object, a motor according to one aspect of the present invention has a housing including a housing base and a housing shaft portion provided in the housing base and extending in a direction along a rotation center axis, a motor stator arranged radially outside the housing shaft portion, a motor rotor provided between the motor stator and the housing shaft portion, a bearing provided radially inside the motor rotor and rotatably supporting the motor rotor on the housing shaft portion, a seal structure provided on the opposite side of the motor rotor to the housing base in the axial direction of the motor rotor (e.g., on the output shaft 17 side in the embodiment) and sealingly sealing between the motor rotor and the housing shaft portion, and a resolver that detects rotation of the motor rotor, the resolver being provided radially outside the bearing and on the opposite side of the motor stator to the housing base in the axial direction in the direction along the rotation center axis (e.g., on the output shaft 17 side in the embodiment), and the resolver includes a differential type incremental resolver.

[0008] According to this, the bearing is provided on the radially inner side of the motor rotor. The output shaft side of the motor rotor is sealed with a lid or the like during use, so that dust generated at the bearing can be prevented from flowing out to the outside, for example to the vacuum atmosphere side. Even if metal powder generated due to wear of the bearing gets inside the motor, the metal powder is adsorbed to the motor stator. Therefore, the motor can prevent dust generated inside from flowing out to the outside. Also, since the metal powder is prevented from flowing out to the resolver side, a decrease in the detection accuracy of the resolver can be suppressed. Furthermore, since a differential type incremental resolver is provided as the resolver, erroneous detection due to magnetic force (magnetic field) generated from the motor stator can be suppressed.

[0009] In a preferred embodiment of the motor, the resolver further includes an absolute resolver, and the motor stator, the absolute resolver, and the incremental resolver are arranged in this order along the central axis of rotation. In this manner, the absolute resolver functions as a magnetic shield for the incremental resolver, and can prevent the magnetic force (magnetic field) generated by the motor stator from reaching the incremental resolver.

[0010] In a preferred embodiment of the motor, the absolute resolver and the incremental resolver each have a resolver stator having an excitation coil and a resolver rotor provided radially inside the resolver stator, and the resolver rotor of the absolute resolver is made of low carbon steel. In this way, the resolver rotor is made of a soft magnetic material and can provide good shielding between the motor stator and the incremental resolver.

[0011] In a preferred embodiment of the motor, the absolute resolver and the incremental resolver each have a resolver stator having an excitation coil and a resolver rotor provided radially inside the resolver stator, and the resolver rotor of the incremental resolver is made of low carbon steel and has a plurality of salient poles, so that the resolver rotor can detect the rotation angle of the motor with good accuracy.

[0012] In a preferred embodiment of the motor, the resolver includes a resolver stator having an excitation coil and a resolver rotor disposed radially inside the resolver stator, and a resolver partition wall formed of a non-magnetic material is provided between the resolver rotor and the resolver stator. This allows the resolver partition wall to separate a space in which the resolver rotor is disposed from a space in which the resolver stator is disposed, and can prevent gas on the atmospheric side where the resolver stator is disposed from flowing out to the vacuum atmosphere side where the resolver rotor is disposed. In addition, a resolver is used as an angle detector, and no electronic elements are disposed in the motor. Therefore, even when the motor is used in a high-temperature environment, the angle can be detected satisfactorily.

[0013] In a preferred embodiment of the motor, a motor partition is provided between the motor stator and the motor rotor to separate the space in which the motor stator is disposed from the space in which the motor rotor is disposed. In this manner, the motor partition can prevent gas on the atmospheric side, where the motor stator is disposed, from flowing out to the vacuum atmosphere side, where the motor rotor is disposed.

[0014] In a preferred embodiment of the motor, the outer diameter of the motor rotor is smaller than the outer diameter of the resolver rotor, so that the rotating structure including the motor rotor and the resolver rotor can be pulled out as a unit from the output shaft, facilitating replacement and maintenance of the bearings.

[0015] In a preferred embodiment of the motor, the bearing is non-lubricated and has an inner ring provided on the housing shaft portion, an outer ring provided on the motor rotor, and rolling elements provided between the inner ring and the outer ring, at least the rolling elements being made of ceramics. This makes it possible to suppress dust generation from the rolling elements of the bearing due to wear and gas generation in high-temperature environments.

[0016] In a preferred embodiment of the motor, the bearing is non-lubricated and has an inner ring provided on the housing shaft, an outer ring provided on the motor rotor, and rolling elements provided between the inner ring and the outer ring, and the inner ring and the outer ring are made of magnetic iron-based materials. With this, even if dust generated by the bearing wear gets inside the motor, the metal powder is effectively attracted to the permanent magnets of the motor stator and the motor rotor.

[0017] In a preferred embodiment of the motor, a connecting portion made of a magnetic material is disposed between the motor stator and the resolver in a direction along the central axis. This allows the connecting portion to shield the magnetic force (magnetic field) generated by the motor stator, thereby improving the detection accuracy of the resolver. The connecting portion can also absorb metal powder generated by wear.

[0018] In a preferred embodiment of the motor, the motor has an outer ring pressing part provided on the opposite side of the motor rotor from the housing base in the axial direction (e.g., the output shaft 17 side in the embodiment) and fixed to the outer ring of the bearing, and an inner ring pressing part provided on the opposite side of the housing shaft from the housing base in the axial direction (e.g., the output shaft 17 side in the embodiment) and fixed to the inner ring of the bearing, and the seal structure has a labyrinth structure formed by the outer ring pressing part and the inner ring pressing part. This allows dust generated from the motor due to wear of the bearing, etc., to be blocked by the seal structure and prevented from leaking out.

[0019] In a preferred embodiment of the motor, the motor stator is disposed in a space closer to the atmosphere than the space in which the motor rotor is disposed, thereby making it possible to improve the cooling efficiency of the motor stator compared to a case in which the motor stator is disposed in the same space as the motor rotor, for example in a vacuum atmosphere.

[0020] In a preferred embodiment of the motor, the motor rotor includes a samarium-cobalt permanent magnet, which prevents demagnetization even when the motor is used in a high-temperature environment, and allows the motor rotor to be rotated satisfactorily.

[0021] A preferred embodiment of the motor includes a motor control circuit that supplies a drive current to an excitation coil of the motor stator based on a detection signal from the resolver, and the motor control circuit excites the absolute resolver and then excites the incremental resolver when power is turned on. With this, the motor control circuit can determine the angle (position) of the motor rotor when power is turned on based on absolute angle information from the absolute resolver. The motor control circuit can then detect the precise position of the motor rotor based on a resolver signal from the incremental resolver. The motor control circuit can also constantly monitor the rotational torque and speed ripple based on the detection signal from the resolver. This makes it possible to quickly find, for example, an abnormality in a bearing, or to know when to replace the bearing. Effect of the Invention

[0022] According to the present invention, it is possible to provide a motor that can suppress the outflow of dust to the outside. [Brief description of the drawings]

[0023] [Figure 1] FIG. 1 is an explanatory diagram illustrating a state in which a motor according to an embodiment is used. [Diagram 2] FIG. 2 is a cross-sectional view that illustrates a schematic diagram of the motor according to the embodiment. [Diagram 3]FIG. 3 is a cross-sectional view taken along line III-III' of FIG. [Figure 4] FIG. 4 is an enlarged cross-sectional view of a first bearing of the motor according to the embodiment. [Diagram 5] FIG. 5 is an enlarged cross-sectional view showing a motor stator, a motor rotor, and a motor bulkhead of the motor according to the embodiment. [Figure 6] FIG. 6 is an enlarged cross-sectional view showing a resolver and a resolver partition wall of the motor according to the embodiment. [Figure 7] FIG. 7 is a cross-sectional view that illustrates a schematic configuration of an incremental resolver included in the motor according to the embodiment. [Figure 8] FIG. 8 is a block diagram showing an example of the configuration of a signal processing circuit included in the motor control circuit. [Figure 9] FIG. 9 is a flow chart for explaining a method of driving the incremental resolver and the absolute resolver. [Figure 10] FIG. 10 is a cross-sectional view illustrating a motor according to a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] The present invention will be described in detail below with reference to the drawings. Note that the present invention is not limited to the following modes for carrying out the invention (hereinafter, referred to as embodiments). Furthermore, the components in the following embodiments include those that a person skilled in the art can easily imagine, those that are substantially the same, and those that are within the so-called equivalent range. Furthermore, the components disclosed in the following embodiments can be appropriately combined.

[0025] FIG. 1 is an explanatory diagram for explaining a state of use of a motor according to an embodiment. As shown in FIG. 1, a semiconductor manufacturing apparatus 100 will be described as an example of a manufacturing apparatus in which a motor 1 is used. The semiconductor manufacturing apparatus 100 includes a chamber 101, a motor 1, a motor control circuit 90, a control device 99, and a conveying device 110. The motor 1 rotates an output shaft 17 (see FIG. 2) about a rotation center axis AX. The conveying device 110 including a conveying table 111 is disposed inside the chamber 101 and is connected to the motor 1 through an opening 102. The semiconductor manufacturing apparatus 100 rotates the conveying table 111 by driving the motor 1. The semiconductor manufacturing apparatus 100 moves a workpiece (transported object) 120 in a vacuum atmosphere Va mounted on the conveying table 111. The workpiece 120 is, for example, a semiconductor substrate, a workpiece, or a tool.

[0026] The motor 1 can transmit a rotational force directly to the conveying table 111 and the workpiece 120 without using a transmission mechanism such as a gear, a belt, or a roller, and can rotate the workpiece 120. The motor 1 is a so-called direct drive motor. In this embodiment, the axial direction is the direction along the central axis of rotation AX.

[0027] The control device 99 includes an input circuit, a CPU (Central Processing Unit) which is a central processing unit, a memory which is a storage device, and an output circuit (none of which are shown). The control device 99 generates a motor rotation command i for controlling the motor 1 according to a program stored in the memory, and outputs the command to the motor control circuit 90.

[0028] When a motor rotation command i is input from the control device 99, the motor control circuit 90 outputs a drive signal from a CPU (Central Processing Unit) 91 to a three-phase amplifier (hereinafter referred to as an AMP (Amplifier) ​​92), and a drive current Mi is supplied from the AMP 92 to the motor 1. The motor 1 is driven to rotate by the drive current Mi, and rotates the conveying table 111. This moves the workpiece 120 mounted on the conveying table 111. Note that the conveying device 110 may have other members such as an arm for conveying a wafer in addition to the conveying table 111, and a configuration according to the workpiece 120 can be appropriately adopted.

[0029] When the conveyor table 111 rotates, a detection signal (resolver signal) Sr is output from an angle detector such as a resolver 60 (see FIG. 2) that detects the rotation angle. The motor control circuit 90 digitally converts the detection signal Sr using a resolver to digital converter (hereinafter referred to as an RDC (Resolver to Digital Converter) 93). Based on the digital information of the detection signal Sr from the RDC 93, the CPU 91 determines whether or not the workpiece 120 has reached a command position, and if the workpiece 120 has reached the command position, stops the drive signal to the AMP 92.

[0030] Furthermore, the motor control circuit 90 can constantly monitor the rotational torque and the speed ripple based on the detection signal Sr of the resolver 60. This allows the motor control circuit 90 to quickly detect the occurrence of an abnormality in the first bearing 21A and the second bearing 21B shown in Fig. 2, for example, or to know when to replace the first bearing 21A and the second bearing 21B.

[0031] In general, in the semiconductor manufacturing apparatus 100, the integration degree of semiconductors is increasing, and at the same time, the pattern width of ICs is becoming finer, leading to higher density. In order to manufacture wafers (semiconductor components) that can accommodate this fineness, a high degree of uniformity in wafer quality is required. In order to meet this demand, it is important to further reduce the impurity gas concentration in the vacuum atmosphere Va. For this reason, in the motor 1 disposed in the mounting hole (opening 102) of the chamber 101, it is also necessary to separate the space of the vacuum atmosphere Va from the external air atmosphere At.

[0032] In this embodiment, the inside of the chamber 101 is a vacuum atmosphere Va. However, the inside of the chamber 101 is not limited to a vacuum environment, and may be an atmosphere different from the atmospheric atmosphere At, such as a reduced pressure environment or an environment filled with a process gas such as nitrogen gas or a rare gas. Also, a vacuum and high temperature environment such as a diffusion furnace used in semiconductor manufacturing can be applied to the inside of the chamber 101. Also, in this embodiment, the "atmosphere side" is a space with a higher pressure than the "vacuum side" (vacuum atmosphere Va). Or, the "atmosphere side" may be a space with a lower ratio of process gas than the "vacuum side" (vacuum atmosphere Va).

[0033] FIG. 2 is a cross-sectional view showing a schematic diagram of a motor according to an embodiment. FIG. 3 is a cross-sectional view taken along line III-III' in FIG. 2. FIG. 2 is a cross-sectional view showing a motor 1 cut along a virtual plane including the central axis of rotation AX. In the following description, the direction along the central axis of rotation AX toward the output shaft 17 (vacuum atmosphere Va) may be referred to as "upper" or simply "up". Also, the direction along the central axis of rotation AX toward the housing base 11 (air atmosphere At) may be referred to as "lower" or simply "down".

[0034] 2 to 10 are exaggerated and shown in a schematic manner to facilitate understanding. For example, the motor partition 50 is shown thicker than it actually is. Furthermore, the sizes of the gap G0 and the first gap G1 to the third gap G3 are shown larger than they actually are, but the gap G0 and the first gap G1 to the third gap G3 are all minute gaps.

[0035] As shown in Fig. 2, the motor 1 has a housing 10, a motor stator 30, a motor rotor 40, a first bearing 21A, a second bearing 21B, a resolver 60, a motor partition wall 50, a resolver partition wall 70, a connecting portion 15, and an output shaft 17. Note that Figs. 2 and 3 only explain the overall layout relationship of the components, and the detailed connection structure and seal structure between the components will be described later.

[0036] The housing 10 includes a housing base 11, a housing shaft portion 12, a housing outer 13, and a cover portion 14. The housing base 11 is a flat plate-like member extending in a direction intersecting the rotation center axis AX, and is formed in an annular shape with an opening provided at a position overlapping the rotation center axis AX. The housing shaft portion 12 and the housing outer 13 are each a cylindrical member extending in a direction along the rotation center axis AX (hereinafter referred to as the axial direction). The lower end of the housing shaft portion 12 is connected to the inner peripheral edge side of the housing base 11, and the lower end of the housing outer 13 is connected to the outer peripheral edge side of the housing base 11. In other words, the housing outer 13 is disposed facing the radially outer side of the housing shaft portion 12 in the radial direction.

[0037] The lid portion 14 is provided to cover the opening of the housing base 11. The lid portion 14 separates the internal space SP of the housing shaft portion 12 from the atmospheric atmosphere At, and prevents foreign matter from entering the internal space SP.

[0038] Since the housing base 11, the housing shaft portion 12, and the cover portion 14 are partially exposed to a vacuum, vacuum materials that emit less gas in a vacuum and whose emitted gas components are known, such as austenitic stainless steel and aluminum alloys, can be used. Depending on the degree of vacuum to be applied, it is more preferable to perform surface treatments such as electrolytic polishing, smoothing, and oxide coating to reduce the surface area and reduce the release of dissolved gas. In this embodiment, the housing outer 13 is exposed to the air atmosphere At and not exposed to a vacuum, so general structural materials such as cast iron and low carbon steel may be used, and stainless steel may also be used. With this structure, the motor 1 can increase the ratio of structural materials used and reduce the amount of vacuum materials used, which are more expensive than structural materials.

[0039] A motor stator 30, a motor rotor 40, a first bearing 21A, and a second bearing 21B, The motor bulkhead 50 and the connecting portion 15 are fitted between the housing shaft portion 12 and the housing outer 13 .

[0040] The motor stator 30 is disposed radially outside the housing shaft portion 12 and the motor rotor 40, and is maintained in a stationary state. Specifically, the connecting portion 15 is provided to cover the upper side (resolver 60 side) of the motor stator 30, and the motor stator 30 is fixed to the housing outer 13 via the connecting portion 15. As a method for fixing the motor stator 30, for example, the stator core 31 of the motor stator 30 is fastened to the housing 10 (housing outer 13) with a bolt. As a result, the motor stator 30, which is a non-rotating part, is positioned and fixed to the housing base 11. In addition, the motor rotor 40 is provided between the motor stator 30 and the housing shaft portion 12. The first bearing 21A and the second bearing 21B rotatably support the motor rotor 40 on the housing shaft portion 12. That is, the motor rotor 40 is disposed rotatably with respect to the motor stator 30.

[0041] As shown in Fig. 3, the motor stator 30, the motor rotor 40, the first bearing 21A (not shown in Fig. 3), and the second bearing 21B are all annular structures and are arranged concentrically around the rotation axis AX. From the housing shaft portion 12, the bearings (first bearing 21A and second bearing 21B), the motor rotor 40, the motor bulkhead 50, the motor stator 30, and the housing outer 13 are arranged in this order from the housing shaft portion 12 toward the outside in the radial direction. In other words, the motor 1 is a so-called inner rotor type, and the motor rotor 40 is located closer to the rotation axis AX than the motor stator 30. In other words, the motor rotor 40 is arranged on the vacuum atmosphere Va side, and the motor stator 30 is arranged on the air atmosphere At side.

[0042] The motor stator 30 is formed by overlapping electromagnetic steel sheets, and includes a stator core 31, an insulator 34 (see FIG. 2), and an excitation coil 35 (see FIG. 2). The motor stator 30 is formed, for example, by bonding steel sheets or by in-die crimping. This makes it easy to process the stator core 31, and good magnetic characteristics of the motor stator 30 can be obtained. The stator core 31 has a back yoke 32 and teeth 33. The back yoke 32 is an annular member and is arranged facing the inner peripheral surface of the housing outer 13 with a space therebetween. A plurality of teeth 33 are arranged in the circumferential direction on the back yoke 32, and are arranged at equal intervals. The teeth 33 each protrude radially inward from the back yoke 32. The motor stator 30 is not limited to such an integral core, and may be a split core in which a plurality of split stator cores 31 are arranged. The excitation coils 35 are wound around the teeth 33 of the stator core 31 via the insulators 34. A wiring for supplying electric power from a power source is connected to the motor stator 30, and a driving current Mi is supplied from the motor control circuit 90 to the exciting coil 35 through this wiring.

[0043] The motor windings and insulator 34 (insulating material) constituting the excitation coil 35 shown in Fig. 2 are both made of heat-resistant materials. The motor windings and insulator 34 (insulating material) have a heat resistance of, for example, 200°C or higher. This allows the motor 1 to operate satisfactorily in a high-temperature environment. The motor windings are coated with, for example, polyimide. The material of the insulator 34 is, for example, insulating paper, or a resin material, or a combination of insulating paper and a resin material.

[0044] The motor rotor 40 includes a rotor yoke 41, a magnet 42, and a space 43 (see FIG. 2). The rotor yoke 41 is a cylindrical member, and the outer diameter of the rotor yoke 41 is smaller than the inner diameter of the stator core 31. The motor rotor 40 is provided in an annular shape on the radially inner side of the motor stator 30 with a gap that becomes a magnetic gap MG. The rotor yoke 41 is formed of low carbon steel, which is a ferromagnetic material, and it is preferable that the surface is nickel plated. By applying nickel plating, the rotor yoke 41 can be prevented from rusting and outgassing can be reduced.

[0045] As shown in FIG. 3, the magnet 42 is attached to the outer periphery of the rotor yoke 41. That is, the motor stator 30 (stator core 31) is disposed radially outside the magnet 42 via the motor bulkhead 50. Since the rotating motor rotor 40 and the motor stator 30, which is a non-rotating part, are disposed without contact, it is possible to suppress the generation of foreign matter. The magnet 42 is disposed such that the south poles and north poles are alternately disposed at equal intervals in the circumferential direction of the rotor yoke 41. The number of poles of the motor rotor 40 is, for example, 20 poles. Note that the number of poles of the motor rotor 40 and the number of slots of the motor stator 30 are not limited to a 20-pole, 18-slot configuration, and can be appropriately changed as necessary.

[0046] In this embodiment, it is preferable to use a samarium-cobalt permanent magnet for the magnet 42. This prevents demagnetization even when the motor 1 is used in a high-temperature environment, and allows the motor rotor 40 to be rotated satisfactorily. However, the magnet 42 is not limited to this, and other materials such as a neodymium magnet may be used.

[0047] 2 is a space that prevents magnetic flux from flowing around the end face of the magnet 42. The step dimension Y (see FIG. 4) of the rotor yoke 41 that forms the space 43 is preferably about 1 / 3 to 1 / 2 of the thickness dimension X (see FIG. 4) of the magnet 42. If this range is exceeded, magnetic flux will flow around the upper end face of the magnet 42 of the motor rotor 40, preventing the magnetic flux from flowing around the stator core 31, resulting in a decrease in output torque.

[0048] The motor partition 50 is provided in the magnetic gap MG between the motor stator 30 and the motor rotor 40, and separates the space in which the motor rotor 40 is disposed (vacuum atmosphere Va side) from the space in which the motor stator 30 is disposed (air atmosphere At side). A detailed configuration of the motor partition 50 will be described later.

[0049] An output shaft 17 is connected to the upper end of the rotor yoke 41. The output shaft 17 rotates together with the rotor yoke 41, and transmits the torque of the motor 1 to the outside (for example, the conveyor table 111).

[0050] The first bearing 21A and the second bearing 21B are provided between the outer periphery of the housing shaft portion 12 and the inner periphery of the rotor yoke 41. The first bearing 21A and the second bearing 21B are rolling bearings having an inner ring 22, an outer ring 23, and a rolling element 24, respectively. The rolling element 24 is provided between the inner ring 22 and the outer ring 23. In the direction along the rotation center axis AX, the first bearing 21A is disposed on the output shaft 17 side, and the second bearing 21B is disposed on the housing base 11 side. The inner ring 22 of the first bearing 21A and the inner ring 22 of the second bearing 21B are fixed to the housing shaft portion 12. The outer ring 23 of the first bearing 21A and the outer ring 23 of the second bearing 21B are fixed to the rotor yoke 41 of the motor rotor 40.

[0051] An inner ring spacer 25 is provided between the inner ring 22 of the first bearing 21A and the inner ring 22 of the second bearing 21B. An outer ring spacer 26 is provided between the outer ring 23 of the first bearing 21A and the outer ring 23 of the second bearing 21B. This defines the positions of the first bearing 21A and the second bearing 21B in the axial direction. An inner ring holder 16 is connected to the upper end of the housing shaft portion 12, and the position of the upper end of the inner ring 22 of the first bearing 21A is fixed by the inner ring holder 16. The output shaft 17 also serves as the outer ring holder, and the position of the upper end of the outer ring 23 of the first bearing 21A is fixed by the output shaft 17.

[0052] A lower end of the inner ring 22 of the second bearing 21B is fixed to the housing base 11. Moreover, a lower end of the outer ring 23 of the second bearing 21B is fixed to the rotor yoke 41. With this configuration, the first bearing 21A, spacers (inner ring spacer 25 and outer ring spacer 26), and second bearing 21B are positioned so that no gap (backlash) occurs in the axial direction, forming a fixed position preload type rotation support structure.

[0053] A seal structure LS is provided on the output shaft 17 side of the motor rotor 40 (the side opposite the housing base 11 in the axial direction) to seal between the motor rotor 40 and the housing shaft portion 12 without contact. More specifically, the seal structure LS is configured by a minute gap formed between the output shaft 17 and the inner ring pressing portion 16 on the output shaft 17 side of the first bearing 21A. This makes it possible to suppress dust generated due to wear of the first bearing 21A and the second bearing 21B from flowing out to the vacuum atmosphere Va side.

[0054] Of the inner ring 22, outer ring 23, and rolling elements 24 of the first bearing 21A and the second bearing 21B, at least the rolling elements 24 are made of ceramics. For example, silicon nitride, zirconia, alumina, etc. are used as the material for the rolling elements 24. This makes it possible to suppress dust generation due to wear from the rolling elements 24 of the first bearing 21A and the second bearing 21B and gas generation in a high-temperature environment.

[0055] Furthermore, the inner ring 22 and the outer ring 23 of the first bearing 21A and the second bearing 21B are made of a magnetic iron-based material. The magnetic iron-based material is, for example, martensitic stainless steel. With this, even if dust (metal powder) generated by wear of the bearings (first bearing 21A and second bearing 21B) gets inside the motor 1, it is attracted to the magnet 42 of the motor rotor 40 or the motor bulkhead 50 (where the magnetic force (magnetic field) of the motor stator 30 acts through a wall portion 51 (see FIG. 5 described later)).

[0056] The resolver 60 is provided radially outward of the first bearing 21A and the second bearing 21B and axially closer to the output shaft 17 than the motor stator 30. The resolver 60 is an angle detector that detects the rotation of the motor rotor 40.

[0057] The resolver 60 includes an incremental resolver 60A and an absolute resolver 60B. The incremental resolver 60A is a differential type detector that detects a relative angle with high resolution. The absolute resolver 60B is a detector that detects the absolute angle of one rotation of the output shaft 17. The motor stator 30, the absolute resolver 60B, and the incremental resolver 60A are arranged in this order along the direction of the central axis of rotation. With this arrangement, the absolute resolver 60B functions as a magnetic shield for the incremental resolver 60A, and can prevent the magnetic force (magnetic field) generated by the motor stator 30 from reaching the incremental resolver 60A side.

[0058] The incremental resolver 60A includes a resolver stator 61A and a resolver rotor 62A. The absolute resolver 60B includes a resolver stator 61B and a resolver rotor 62B. The resolver rotors 62A and 62B are formed of, for example, low carbon steel. The resolver rotors 62A and 62B are arranged opposite the resolver stators 61A and 61B with a predetermined gap therebetween, and are rotatable relative to the resolver stators 61A and 61B. Specifically, the resolver stators 61A and 61B are fixed to the housing outer 13. As a result, the resolver stators 61A and 61B are positioned and fixed relative to the motor stator 30 and the housing base 11, and are maintained in a stationary state. In addition, the resolver rotors 62A and 62B are fixed to the outer periphery of the output shaft 17. The resolver rotors 62A and 62B rotate together with the motor rotor 40.

[0059] A resolver partition 70 is provided between the resolver rotors 62A, 62B and the resolver stators 61A, 61B. The resolver partition 70 is provided to cover the resolver stators 61A, 61B. The resolver partition 70 also serves as an attachment structure for the chamber 101 (see FIG. 1), and is fixed to the chamber 101 at a portion that protrudes radially outward beyond the housing outer 13. A groove 70b is provided in a partition upper surface 70a of the resolver partition 70. The groove 70b is formed in an annular shape centered on the central axis of rotation AX. A sealing member (not shown), such as an O-ring, fitted into the groove 70b provides a seal between the partition upper surface 70a and the chamber 101.

[0060] With the above-mentioned configuration, the motor stator 30 is disposed closer to the air atmosphere At than the motor rotor 40. The bearings (first bearing 21A and second bearing 21B) are provided radially inside the motor rotor 40. The resolver 60 is provided closer to the output shaft 17 than the motor stator 30 in the axial direction. The output shaft 17 side of the motor rotor 40 in the axial direction is sealed with a lid or the like during use, so that dust generated at the bearing can be prevented from flowing out to the outside (to the vacuum atmosphere Va side). Even if metal powder generated by the wear of the bearing goes around inside the motor 1, the metal powder is attracted to the motor bulkhead 50 (where the magnetic force (magnetic field) of the motor stator 30 acts through the wall 51). Therefore, the motor 1 can prevent dust generated inside from flowing out to the outside.

[0061] In addition, the housing 10 is provided with an exhaust port 80 that is connected to the outside. This allows gas in the space in which the motor stator 30 is arranged to be exhausted to the outside, improving the cooling efficiency of the motor stator 30. In addition, as shown in FIG. 2, the outer diameter of the motor rotor 40 is smaller than the outer diameter of the resolver rotors 62A, 62B. Therefore, the rotating structure including the motor rotor 40 and the resolver rotors 62A, 62B can be pulled out as a unit from the output shaft 17 side simply by removing the inner ring retaining portion 16 from the housing shaft portion 12. This makes it easy to replace or maintain the bearings (first bearing 21A and second bearing 21B).

[0062] Next, the detailed structure of each component of the motor 1 will be described. FIG. 4 is an enlarged cross-sectional view of the first bearing of the motor according to the embodiment. As shown in FIG. 4, the inner ring pressing portion 16 is fixed to the upper end of the housing shaft portion 12 by a bolt BT1. The inner ring pressing portion 16 is an annular member having an opening that is connected to the internal space SP. However, the inner ring pressing portion 16 may be a flat plate that covers the internal space SP. A step portion 16a is formed on the outer periphery of the inner ring pressing portion 16 at a portion that protrudes radially outward from the housing shaft portion 12. The upper end of the inner ring 22 of the first bearing 21A contacts the step portion 16a. The lower end of the inner ring 22 of the first bearing 21A contacts the inner ring spacer 25. The inner ring 22 of the first bearing 21A is positioned in the axial direction by being sandwiched between the step portion 16a and the inner ring spacer 25.

[0063] The output shaft 17 is fixed to the upper end of the rotor yoke 41 of the motor rotor 40 by bolts BT2. A step portion 17b is formed on the output shaft 17 at a portion that protrudes radially inward from the inner circumferential surface of the rotor yoke 41. The upper end of the outer ring 23 of the first bearing 21A contacts the step portion 17b. The lower end of the outer ring 23 of the first bearing 21A contacts the outer ring spacer 26. The outer ring 23 of the first bearing 21A is positioned in the axial direction by being sandwiched between the step portion 17b and the outer ring spacer 26.

[0064] The output shaft 17 further has a flange portion 17a. The flange portion 17a is an annular member extending radially inward from the inner peripheral surface of the output shaft 17. The flange portion 17a is provided so as to cover the space between the inner ring 22 and the outer ring 23 of the first bearing 21A. The inner peripheral surface of the flange portion 17a is disposed opposite the outer peripheral surface of the inner ring holding portion 16 with a gap G0 therebetween, thereby forming a seal structure LS. The seal structure LS preferably employs a labyrinth structure. The labyrinth structure may have any configuration, but for example, a groove portion may be formed at a position opposite the flange portion 17a of the inner ring holding portion 16, and the gap G0 may be formed in a substantially C-shape in cross section.

[0065] The output shaft 17 also serves as a support structure for the resolver rotors 62A, 62B. That is, the output shaft 17 has a protruding portion 17d that protrudes radially outward beyond the motor rotor 40, and a step portion 17c is formed by a portion fixed to the motor rotor 40 and the protruding portion 17d. The resolver rotors 62A, 62B are incorporated into the step portion 17c and fixed with bolts BT3. With this structure, the resolver rotors 62A, 62B rotate integrally with the output shaft 17 and the motor rotor 40.

[0066] 5 is an enlarged cross-sectional view of the motor stator, motor rotor, and motor bulkhead of the motor according to the embodiment. The lid 14 of the housing 10 is fixed to the housing base 11 with bolts BT4. The lid 14 is formed with a protrusion that protrudes into the internal space SP of the housing shaft 12, and a sealing member SL1 such as an O-ring seals the gap between the outer periphery of the protrusion and the inner periphery of the housing shaft 12.

[0067] The housing outer 13 is fixed to the outer edge side of the housing base 11 with bolts BT5. A plurality of steps 11a, 11b, 11c, 11d, and 11e are formed on the upper surface of the housing base 11 between the housing shaft portion 12 and the housing outer 13. The steps 11a, 11b, 11c, 11d, and 11e are provided in this order from the housing shaft portion 12 toward the outside in the radial direction, and the heights of the upper surfaces decrease in the order of the steps 11a, 11b, 11c, 11d, and 11e.

[0068] The lower end of the inner ring 22 of the second bearing 21B contacts the upper surface of the step portion 11a. The upper end of the inner ring 22 of the second bearing 21B contacts the inner ring spacer 25. The inner ring 22 of the second bearing 21B is sandwiched between the step portion 11a and the inner ring spacer 25 to fix its axial position. A flange portion 41a protruding radially inward from the inner peripheral surface is formed on the lower end side of the rotor yoke 41. The lower end of the outer ring 23 of the second bearing 21B contacts the upper surface of the flange portion 41a. The upper end of the outer ring 23 of the second bearing 21B contacts the outer ring spacer 26. The outer ring 23 of the second bearing 21B is sandwiched between the flange portion 41a and the outer ring spacer 26 to fix its axial position. In addition, since stepped portions 11b and 11c are formed in the housing base 11, the outer ring 23 of the second bearing 21B and the lower end side of the rotor yoke 41 are provided without contacting the housing base 11. In addition, the upper end of the magnet 42 is positioned by contacting the stepped portion 41b formed on the outer periphery of the rotor yoke 41.

[0069] Next, a detailed configuration of the motor partition 50 will be described. As shown in Fig. 5, the motor partition 50 has a wall portion 51, a top plate portion 52, and a flange portion 53. The motor partition 50 is a partition that seals the space in which the motor stator 30 is arranged (on the air atmosphere At side) so that gas does not flow into the space in which the motor rotor 40 is arranged (on the vacuum atmosphere Va side).

[0070] Specifically, the wall portion 51 of the motor partition wall 50 is a cylindrical member extending in the axial direction and is disposed between the stator core 31 and the magnet 42 fixed to the rotor yoke 41. The wall portion 51 faces the outer periphery of the magnet 42 with a first gap G1 therebetween. In other words, the first gap G1 is a gap formed between the motor partition wall 50 and the motor rotor 40 in the radial direction. The thickness of the wall portion 51 in the radial direction is 40% or more and 80% or less of the length of the gap between the stator core 31 and the magnet 42 fixed to the rotor yoke 41. This can improve the strength of the motor partition wall 50 and suppress deformation of the motor partition wall 50. In addition, contact between the motor partition wall 50 and the motor rotor 40, which is a rotating part, can be suppressed.

[0071] The top plate portion 52 is connected to an upper end side of the wall portion 51 and extends radially outward. The top plate portion 52 is provided to cover at least a portion of the motor stator 30. In other words, the top plate portion 52 is disposed closer to the output shaft 17 than the stator core 31, the insulator 34, and the excitation coil 35 in the axial direction.

[0072] The connecting portion 15 is provided to cover the upper surface and the radial outer side of the top plate portion 52. Specifically, the connecting portion 15 has a connecting top plate portion 15a and a connecting wall portion 15b. The connecting wall portion 15b is a cylindrical member, extends along the axial direction, and is disposed between the inner circumferential surface of the housing outer 13 and the outer circumferential surface of the insulator 34 and the top plate portion 52. The connecting top plate portion 15a is connected to the upper end side of the connecting wall portion 15b and extends radially inward. The connecting top plate portion 15a is provided to overlap with the top plate portion 52 of the motor partition wall 50.

[0073] A flange portion 13a extending radially inward is provided on the inner circumferential surface of the housing outer 13. The upper end of the connecting wall portion 15b is fixed to the lower surface of the flange portion 13a with bolts BT6. Furthermore, the stator core 31 of the motor stator 30 is fixed to the lower end of the connecting wall portion 15b with bolts BT7. With this configuration, the motor stator 30 is fixed to the housing outer 13 of the housing 10 via the connecting portion 15.

[0074] A portion of the inner peripheral surface 15c side of the connecting top plate portion 15a overlaps with the top plate portion 52. The top plate portion 52 is fixed to the connecting top plate portion 15a with bolts BT8. As a result, the top plate portion 52 is fixed to the housing outer 13 via the connecting portion 15. In addition, the gap between the lower surface of the connecting top plate portion 15a and the upper surface of the top plate portion 52 is sealed with a sealing member SL3 such as an O-ring.

[0075] Also, the inner peripheral surface 15c of the connecting top plate portion 15a is provided facing the outer peripheral surface 41c of the rotor yoke 41 with a third gap G3. The size of the third gap G3 is smaller than the size of the first gap G1. This makes it possible to prevent dust generated due to wear of the first bearing 21A and the second bearing 21B from flowing through the third gap G3 to the resolver 60 side. Also, as described above, the connecting portion 15 is fixed and positioned on the housing outer 13, and this makes it possible to ensure the distance (third gap G3) between the rotor yoke 41 of the motor rotor 40 and the connecting portion 15 within a predetermined range.

[0076] The flange portion 53 of the motor partition wall 50 is connected to the lower end side of the wall portion 51 and extends radially inward. The flange portion 53 is fixed to the upper surface of the step portion 11d of the housing base 11 by a bolt BT9. A sealing member SL2 such as an O-ring seals the gap between the lower surface of the flange portion 53 and the upper surface of the step portion 11d. With this configuration, the space surrounded by the motor partition wall 50, the housing base 11, the housing outer 13, and the connecting portion 15 is sealed. The motor stator 30 is provided in the space surrounded by the motor partition wall 50, the housing base 11, the housing outer 13, and the connecting portion 15. The motor rotor 40 and the bearings (the first bearing 21A and the second bearing 21B) are provided in the space surrounded by the motor partition wall 50, the housing base 11, the housing shaft portion 12, and the output shaft 17. This can improve the positioning accuracy of each component and the rigidity of the motor 1.

[0077] A non-magnetic material is used for the motor partition 50. For example, austenitic stainless steel is suitable as the material for the motor partition 50. Therefore, it is possible to suppress the decrease in magnetic force (magnetic field) when driving the motor rotor 40 through the wall portion 51. The motor partition 50 can be formed as a cylindrical integral molding by, for example, applying deep drawing to a non-magnetic stainless steel plate. The wall portion 51 is formed thinner than the top plate portion 52 and the flange portion 53. Specifically, while the top plate portion 52 and the flange portion 53 have a thickness of several mm, the wall portion 51 is stretched to a thickness of 0.2 mm to 0.5 mm. This makes it possible to suppress magnetic loss when driving the motor rotor 40 while ensuring the rigidity and airtightness of the motor partition 50. In addition, since the first gap G1 is small, it is possible to improve the magnetic coupling between the motor stator 30 and the motor rotor 40, and it is possible to rotate and drive the motor rotor 40 well.

[0078] The connecting portion 15 is made of a magnetic material. The connecting portion 15 is a soft magnetic material, and is made of, for example, low carbon steel with a carbon concentration of 0.48% or less. An example of the low carbon steel is S45C as specified by the JIS standard. Therefore, the connecting portion 15 functions as a shield and can prevent the magnetic force (magnetic field) generated by the motor stator 30 from reaching the resolver 60 side.

[0079] More specifically, a third gap G3 between inner peripheral surface 15c of connecting portion 15 and outer peripheral surface 41c of rotor yoke 41 in the radial direction is about 0.1 mm or more and 0.4 mm or less. The length of third gap G3 between inner peripheral surface 15c of connecting portion 15 and outer peripheral surface 41c of rotor yoke 41 in the direction along the central axis of rotation is about 1 mm or more and 4 mm or less. Furthermore, a thickness t of a portion of connecting portion 15 facing rotor yoke 41 is 1 mm or more. Here, thickness t is the thickness of connecting portion 15 on the radial inner side (rotor yoke 41 side) of bolt BT10 (see FIG. 6).

[0080] With this configuration, a magnetic circuit is formed in which the magnetic force (magnetic field) generated from the motor stator 30 passes through the rotor yoke 41, the third gap G3, and the connecting portion 15 and returns to the motor stator 30. This makes it possible to prevent the magnetic force (magnetic field) generated by the drive current Mi flowing through the excitation coil 35 from propagating through the motor rotor 40 and reaching the resolver 60. As a result, the motor 1 can prevent erroneous detection of the position information of the resolver 60.

[0081] In addition, since a part of the connecting portion 15 (the inner peripheral surface 15c of the connecting top plate portion 15a) is exposed to the vacuum atmosphere Va, it is preferable to use the same material as the rotor yoke 41 of the motor rotor 40.

[0082] With the above-mentioned configuration, even if metal powder is generated due to wear of the first bearing 21A and the second bearing 21B, the seal structure LS (see FIG. 4) provided on the output shaft side of the first bearing 21A can prevent the metal powder from flowing out to the vacuum atmosphere Va. Even if the metal powder gets inside the motor 1 from the lower side (housing base 11 side) of the second bearing 21B, it is attracted to the motor bulkhead 50 (where the magnetic force (magnetic field) generated by the motor stator 30 acts through the wall portion 51 (see FIG. 5)) or to the connecting portion 15 (where the magnetic force (magnetic field) generated by the motor stator 30 acts), so that it is possible to prevent the metal powder from flowing out to the outside.

[0083] Next, the configuration of the resolver 60 will be described. Fig. 6 is an enlarged cross-sectional view of the resolver and the resolver partition wall of the motor according to the embodiment. As shown in Fig. 6, the resolver stators 61A and 61B are fixed to the upper surface of the flange portion 13a of the housing outer 13 by bolts BT12.

[0084] The resolver stators 61A and 61B have an annular laminated core with a plurality of stator poles formed at equal intervals in the circumferential direction, and a resolver coil is wound around each of the stator poles. A wire for outputting a detection signal (resolver signal) Sr is connected to each resolver coil.

[0085] The resolver rotors 62A, 62B are formed of hollow annular laminated iron cores, and are fixed to the outer stepped portion 17c of the output shaft 17. The location of the resolver 60 is not particularly limited as long as it is closer to the output shaft 17 than the motor stator 30 in the axial direction, and the location is capable of detecting the rotation of the motor rotor 40 (output shaft 17).

[0086] A motor control circuit 90 (see FIG. 1) that controls the motor 1 supplies a drive current Mi to the excitation coil 35 of the motor stator 30 based on the detection signal Sr of the resolver 60. Specifically, when the motor rotor 40 rotates, the output shaft 17 rotates together with the motor rotor 40, and the resolver rotors 62A, 62B also rotate in conjunction with the motor rotor 40. This causes the reluctance between the resolver rotors 62A, 62B and the resolver stators 61A, 61B to change continuously. The resolver stators 61A, 61B detect the change in reluctance and convert the detection signal Sr into a digital signal by the RDC 93. A CPU 91 of the motor control circuit 90 that controls the motor 1 can calculate and process the positions and rotation angles of the output shaft 17 and the motor rotor 40 that are linked to the resolver rotors 62A, 62B per unit time based on the electrical signal of the RDC 93. As a result, the motor control circuit 90 is able to measure the rotation state of the output shaft 17 (for example, the rotation speed, the rotation direction, or the rotation angle, etc.).

[0087] The resolver partition wall 70 has an inner wall portion 71, a resolver top plate portion 72, an attachment portion 73, and a flange portion 74. The inner wall portion 71 is a cylindrical member extending in the axial direction, and is provided between the resolver stators 61A, 61B and the resolver rotors 62A, 62B in the radial direction.

[0088] The resolver top plate portion 72 is connected to an upper end of the inner wall portion 71 and extends radially outward. The resolver top plate portion 72 is provided to cover the resolver stators 61A, 61B. The upper surface of the resolver top plate portion 72 becomes the partition wall upper surface 70a described above. The mounting portion 73 is provided radially outward from the resolver top plate portion 72 and is formed to be thicker than the resolver top plate portion 72. The mounting portion 73 is fixed to the upper end of the housing outer 13 by the bolt BT11. As described above, the mounting portion 73 is fixed to the outer wall of the chamber 101 by a fixing member such as a bolt.

[0089] The flange portion 74 is connected to the lower end of the inner wall portion 71 and extends radially inward. The flange portion 74 is provided so as to overlap the upper surface of the connecting portion 15 and is fixed to the connecting portion 15 by bolts BT10. The gap between the lower surface of the flange portion 74 and the upper surface of the connecting portion 15 is sealed by a sealing member SL4 such as an O-ring.

[0090] With this configuration, the resolver partition 70 can seal the space (vacuum atmosphere Va side) in which the resolver rotors 62A, 62B are arranged so that gas in the space (air atmosphere At side) in which the resolver stators 61A, 61B are arranged does not flow into the space (vacuum atmosphere Va side) in which the resolver rotors 62A, 62B are arranged. That is, the resolver stators 61A, 61B are provided in a space surrounded by the resolver partition 70, the housing outer 13, and the connecting portion 15. The resolver rotors 62A, 62B are provided in a space between the resolver partition 70 and the output shaft 17.

[0091] The outer peripheral surface 71a of the inner wall portion 71 is provided opposite to the outer peripheral surface of the protruding portion 17d of the output shaft 17 with a second gap G2 therebetween. In other words, the second gap G2 is a gap formed between the resolver partition wall 70 and the resolver rotors 62A, 62B in the radial direction. The second gap G2 is larger than the first gap G1 and larger than the third gap G3.

[0092] As a result, even if metal powder is generated due to wear of the first bearing 21A and the second bearing 21B, the metal powder is attracted to the connecting portion 15 when passing through the third gap G3 (where the magnetic force (magnetic field) generated by the motor stator 30 acts), and it is possible to prevent the metal powder from flowing out to the resolver 60 side. In addition, since the second gap G2 is formed large, the rotating portion (the motor rotor 40, the resolver rotors 62A, 62B, the output shaft 17, the first bearing 21A, and the second bearing 21B) can be easily removed to the output shaft 17 side during maintenance, etc.

[0093] Next, a detailed configuration of the differential type incremental resolver 60A will be described. Fig. 7 is a cross-sectional view showing a schematic configuration of an incremental resolver included in a motor according to an embodiment. Fig. 8 is a block diagram showing a configuration example of a signal processing circuit included in a motor control circuit.

[0094] 7, the resolver stator 61A of the incremental resolver 60A has N-phase, for example, 3-phase 18-pole salient poles A11-A16, B11-B16, C11-C16 (first magnetic poles) protruding radially inward, provided at a predetermined interval. 3-phase 18-pole salient poles A21-A26, B21-B26, C21-C26 (second magnetic poles) are provided at intermediate positions between the salient poles A11-A16, B11-B16, C11-C16. These salient poles are arranged in the circumferential direction in the order of A11, C21, B11, A21, C11, B21, A12, C22, . . . Each of the salient poles A11-C26 has three teeth TS1, TS2, and TS3 on the end face on the inner circumferential surface side, and has one excitation winding LA11-LC26 wound around the center. Therefore, the salient poles at 180-degree positions are in phase with each other.

[0095] A plurality of slot teeth TR are formed on the outer circumferential surface of the resolver rotor 62A. Here, the pitch of the slot teeth TR of the resolver rotor 62A is formed such that, for example, if three adjacent teeth TR of the resolver rotor 62A coincide with the teeth TS1, TS2, and TS3 of the salient pole A11 of the resolver stator 61A, the teeth TS1, TS2, and TS3 of the adjacent salient pole C21 are mechanically shifted by 1 / 36 pitch from the slot teeth TR of the resolver rotor 62A.

[0096] Although not shown, the excitation windings LA11-LC26 of the salient poles A11-C26 are connected in series, the excitation windings LA11-LA16 are connected in series, the excitation windings LB11-LB16 are connected in series, and the excitation windings LC11-LC16 are connected in series. In addition, the excitation windings LA21-LA26 are connected in series, the excitation windings LB21-LB26 are connected in series, and the excitation windings LC21-LC26 are connected in series.

[0097] 8, resolver signals fa1, fa2, fb1, fb2, fc1, and fc2 are output from the incremental resolver 60A to the differential amplifier circuit 95. The resolver signals fa1, fa2, fb1, fb2, fc1, and fc2 are output signals from the series-connected excitation windings LA11-LA16, LA21-LA26, LB11-LB16, LB21-LB26, LC11-LC16, and LC21-LC26, respectively.

[0098] More specifically, the resolver signals fa1, fa2, fb1, fb2, fc1, and fc2 are expressed by the following equations (1) to (6). fa1=A0+A1cosθ+A2cos2θ+A3cos3θ+A4cos4θ (1) fb1=A0+A1cos(θ-120°)+A2cos2(θ-120°)+A3cos3(θ-120°)+A4cos4(θ-120°) ··· (2) fc1=A0+A1cos(θ+120°)+A2cos2(θ+120°)+A3cos3(θ+120°)+A4cos4(θ+120°) ··· (3) fa2=A0+A1cos(θ+180°)+A2cos2(θ+180°)+A3cos3(θ+180°)+A4cos4(θ+180°)... (4) fb2=A0+A1cos(θ-300°)+A2cos2(θ-300°)+A3cos3(θ-300°)+A4cos4(θ-300°)... (5) fc2=A0+A1cos(θ+300°)+A2cos2(θ+300°)+A3cos3(θ+300°)+A4cos4(θ+300°) ··· (6)

[0099] Since the resolver signals fa1, fa2, fb1, fb2, fc1, and fc2 are supplied to the differential amplifier circuit 95, the output signals da, db, and dc of the differential amplifier circuit 95 are expressed by the following equations (7), (8), and (9). However, the output signal da is a signal output as the difference between the resolver signals fa1 and fa2. The output signal db is a signal output as the difference between the resolver signals fb1 and fb2. The output signal dc is a signal output as the difference between the resolver signals fc1 and fc2. da=2A1cosθ+2A3cos3θ (7) db=2A1cos(θ-120°)+2A3cos3(θ-120°) ··· (8) dc=2A1cos(θ+120°)+2A3cos3(θ+120°) ··· (9)

[0100] The three-phase output signals da, db, dc of the differential amplifier circuit 95 are supplied to a phase conversion circuit 96. The phase conversion circuit 96 converts the output signals da, db, dc into two-phase AC signals fc(θ) and fs(θ) with third-order harmonic distortion cancelled, as expressed by the following equations (10) and (11). fc(θ)=3A1cosθ / 2=sinωt×cosθ (10) fs(θ)=3A1sinθ / 2=sinωt×sinθ (11)

[0101] These two-phase AC signals fc(θ) and fs(θ) are supplied to a signal processing circuit (RDC 93). In the RDC 93, a counter 93f is initially cleared to zero, thereby setting the digital rotation angle φ to "0".

[0102] Therefore, the multiplication output of the multiplier 93a becomes sinωt×sinθ, and the multiplication output of the multiplier 93b becomes “0”. The subtraction output of the subtractor 93c, i.e., Vsinωt×sin(θ-φ), becomes Vsinωt×sinθ, which is supplied to the synchronous rectifier 93d. The synchronous rectifier 93d outputs an output Vsinθ from which the excitation voltage component has been removed, and outputs this as a speed detection signal to the CPU 91 (see FIG. 1). The output Vsinθ of the synchronous rectifier 93d is also supplied to the voltage-controlled oscillator 93e and converted into a pulse signal corresponding to the voltage, which is supplied to the counter 93f. As a result, the count value (digital rotation angle φ) of the counter 93f becomes equal to the phase angle θ.

[0103] In this state, when the resolver rotor 62A continues to rotate in the same direction, the output of the subtractor 93c increases by the increment of the phase angle θ relative to the digital rotation angle φ, and accordingly the output of the synchronous rectifier 93d also increases by the increment of the phase angle θ, so that the count value of the counter 93f is counted up by the increment of the phase angle θ, and the current digital rotation angle φ corresponding to the rotation of the resolver rotor 62A is output.

[0104] The CPU 91 controls the rotation speed and positioning based on the speed detection signal from the incremental resolver 60A. Since a differential resolver is used as the incremental resolver 60A, erroneous detection due to the magnetic force (magnetic field) generated by the motor stator 30 can be suppressed.

[0105] Next, there will be described an example of an operation sequence of the resolver 60 (the incremental resolver 60A and the absolute resolver 60B) included in the CPU 91 of the motor 1. Fig. 9 is a flow chart for explaining a method of driving the incremental resolver and the absolute resolver.

[0106] 9, when the motor 1 is powered on, the CPU 91 first excites the absolute resolver 60B (step ST1). This allows the CPU 91 to determine the angle (position) of the motor rotor 40 at the time of powering on, based on the absolute angle information from the absolute resolver 60B.

[0107] Next, the CPU 91 stops excitation of the absolute resolver 60B (step ST2) and excites the incremental resolver 60A (step ST3). This allows the CPU 91 to detect a precise position based on the resolver signals fa1, fa2, fb1, fb2, fc1, and fc2 from the incremental resolver 60A, as described above.

[0108] The CPU 91 drives the motor 1 based on the position information, speed detection signal, etc. from the incremental resolver 60A (step ST4) and executes control of the rotation speed and positioning. When the motor 1 is driven, the absolute resolver 60B functions as a shield that blocks the magnetic force (magnetic field) generated from the motor stator 30, and can prevent the magnetic force (magnetic field) generated from the motor stator 30 from reaching the incremental resolver 60A side.

[0109] The shapes and configurations of the components of the motor 1 described above are merely examples and may be modified as appropriate. For example, the resolver partition 70 is not limited to being formed as a single unit, and may be divided into multiple parts. The fixing structure and sealing structure of each component may also be modified as appropriate.

[0110] As described above, the motor 1 of this embodiment includes the housing 10, the motor stator 30, the motor rotor 40, the bearings (the first bearing 21A and the second bearing 21B), the seal structure LS, and the resolver 60. The housing 10 includes the housing base 11 and the housing shaft portion 12 that is provided on the housing base 11 and extends in a direction along the rotation center axis AX. The motor stator 30 is disposed on the radial outside of the housing shaft portion 12. The motor rotor 40 is provided between the motor stator 30 and the housing shaft portion 12. The bearing is provided on the radial inside of the motor rotor 40 and supports the motor rotor 40 rotatably on the housing shaft portion 12. The seal structure LS seals the gap between the motor rotor 40 and the housing shaft portion 12 on the output shaft 17 side of the motor rotor 40. The resolver 60 detects the rotation of the motor rotor 40. The resolver 60 is provided radially outward of the bearings and closer to the output shaft 17 than the motor stator 30 in the direction along the rotation center axis AX. The resolver 60 includes a differential type incremental resolver 60A.

[0111] According to this, the bearing is provided on the radially inner side of the motor rotor 40. Since the output shaft 17 side of the motor rotor 40 is sealed with a lid or the like during use, it is possible to suppress dust generated at the bearing from flowing out to the outside, for example, to the vacuum atmosphere Va side. Even if dust (metal powder) generated by the wear of the bearing goes around inside the motor 1, the metal powder is attracted to the motor bulkhead 50 (by the magnetic force (magnetic field) of the motor stator 30). Therefore, the motor 1 can suppress dust generated inside from flowing out to the outside. Furthermore, since the metal powder is suppressed from flowing out to the resolver 60 side, it is possible to suppress a decrease in the detection accuracy of the resolver 60. Furthermore, since the resolver 60 has a differential type incremental resolver 60A, it is possible to suppress erroneous detection due to the magnetic force (magnetic field) generated from the motor stator 30.

[0112] Moreover, the motor 1 has a motor partition 50 that is provided between the motor stator 30 and the motor rotor 40 and separates the space in which the motor stator 30 is disposed from the space in which the motor rotor 40 is disposed. With this, the motor partition 50 can prevent gas on the atmospheric side, where the motor stator 30 is disposed, from flowing out to the vacuum atmosphere side, where the motor rotor 40 is disposed.

[0113] In the motor 1, the resolver 60 includes resolver rotors 62A and 62B connected to the motor rotor 40, and resolver stators 61A and 61B provided radially outside the resolver rotors 62A and 62B and having excitation coils. A resolver partition 70 is provided between the resolver rotors 62A and 62B and the resolver stators 61A and 61B. This allows the resolver partition 70 to separate the space in which the resolver rotors 62A and 62B are arranged from the space in which the resolver stators 61A and 61B are arranged, and prevents the gas on the atmosphere side where the resolver stators 61A and 61B are arranged from flowing out to the vacuum atmosphere side where the resolver rotors 62A and 62B are arranged. In addition, the resolver 60 is used as an angle detector, and no electronic elements are provided in the motor 1. Therefore, even when the motor 1 is used in a high-temperature environment, the angle can be detected satisfactorily.

[0114] Furthermore, in the motor 1, the outer diameter of the motor rotor 40 is smaller than the outer diameters of the resolver rotors 62A, 62B. This allows the rotating structure including the motor rotor 40 and the resolver rotors 62A, 62B to be pulled out as a unit from the output shaft 17 side, facilitating replacement and maintenance of the bearings (first bearing 21A and second bearing 21B).

[0115] In addition, in the motor 1, the bearings (first bearing 21A and second bearing 21B) are non-lubricated and have an inner ring 22 provided on the housing shaft portion 12, an outer ring 23 provided on the motor rotor 40, and rolling elements 24 provided between the inner ring 22 and the outer ring 23, and among the inner ring 22, the outer ring 23, and the rolling elements 24, at least the rolling elements 24 are made of ceramics. This makes it possible to suppress dust generation due to wear from the rolling elements 24 of the bearing and gas generation in a high-temperature environment.

[0116] In addition, in motor 1, the bearings (first bearing 21A and second bearing 21B) are unlubricated and include an inner ring 22 provided on housing shaft portion 12, an outer ring 23 provided on motor rotor 40, and rolling elements 24 provided between the inner ring 22 and the outer ring 23, with magnetic iron-based members being used for the inner ring 22 and the outer ring 23. With this, even if dust generated by the bearing wear gets inside motor 1, the metal powder is attracted well to the permanent magnets of motor stator 30 and motor rotor 40.

[0117] In addition, in the motor 1, a connecting portion 15 made of a magnetic material is disposed between the motor stator 30 and the resolver 60 in the direction along the central axis of rotation AX. As a result, the connecting portion 15 can shield the magnetic force (magnetic field) generated from the motor stator 30, thereby improving the detection accuracy of the resolver 60. The connecting portion 15 can also adsorb metal powder generated due to wear.

[0118] Moreover, the motor 1 has an outer ring pressing portion (step portion 17b) provided on the output shaft 17 side of the motor rotor 40 and fixed to the outer ring 23 of the bearing, and an inner ring pressing portion 16 provided on the output shaft 17 side of the housing shaft portion 12 and fixed to the inner ring 22 of the bearing, and the seal structure LS has a labyrinth structure formed by the outer ring pressing portion and the inner ring pressing portion 16. With this, dust generated from the motor 1 due to wear of the bearing or the like is blocked by the seal structure LS, and it is possible to prevent the dust from leaking out to the outside.

[0119] Furthermore, in the motor 1, the motor stator 30 is disposed in a space closer to the atmosphere than the space in which the motor rotor 40 is disposed. This allows the cooling efficiency of the motor stator 30 to be improved compared to a case in which the motor stator 30 is disposed in the same space as the motor rotor 40, for example, in a vacuum atmosphere Va.

[0120] Furthermore, in the motor 1, the motor rotor 40 includes a samarium-cobalt permanent magnet. This prevents the magnet 42 from demagnetizing even when the motor 1 is used in a high-temperature environment, so that the motor rotor 40 can be rotated satisfactorily.

[0121] The motor 1 also includes a motor control circuit 90 that supplies a drive current Mi to the excitation coil 35 of the motor stator 30 based on the detection signal Sr of the resolver 60. This allows the motor control circuit 90 to constantly monitor the rotational torque and speed ripple based on the detection signal Sr of the resolver 60. This makes it possible to quickly find, for example, an abnormality in a bearing, or to know when to replace the bearing.

[0122] (Modification) FIG. 10 is a cross-sectional view showing a motor according to a modified example. As shown in FIG. 10, the motor 1A according to the modified example is different from the above-mentioned embodiment in that the housing shaft portion 12A of the housing 10 is solid and columnar. That is, no internal space SP is formed inside the housing shaft portion 12A. This allows the motor 1A according to the modified example to simplify the configuration of the housing 10. Also, the inner ring holding portion 16A can be made into a disk shape without an opening. Also, in this modified example, there is no need to provide a lid portion 14 (see FIG. 2) for sealing the internal space SP. Therefore, the seal structure (see symbol SL1 in FIG. 5) between the internal space SP and the atmospheric atmosphere At can also be omitted. [Explanation of symbols]

[0123] 1, 1A motor 10. Housing 11 Housing Base 12 Housing shaft 15 Connecting part 17 Output shaft 21A No. 1 bearing 21B No. 2 bearing 22 Inner Circle 23 Outer Ring 24 Rolling elements 30 Motor stator 40 Motor rotor 41 Rotor yoke 50 Motor bulkhead 60 Resolver 60A Incremental Resolver 60B Absolute Resolver 61A, 61B Resolver stator 62A, 62B Resolver rotor 70 Resolver bulkhead 90 Motor control circuit 100 Semiconductor manufacturing equipment 101 Chamber 111 Transport table At atmospheric pressure Va Vacuum atmosphere

Claims

1. a housing including a housing base and a housing shaft portion provided on the housing base and extending in a direction along a central axis of rotation; a motor stator disposed radially outside the housing shaft portion; a motor rotor provided between the motor stator and the housing shaft portion; a bearing provided on a radially inner side of the motor rotor and configured to rotatably support the motor rotor on the housing shaft portion; a seal structure provided on an axial side of the motor rotor opposite to the housing base, the seal structure sealingly sealing a gap between the motor rotor and the housing shaft portion; a resolver that detects rotation of the motor rotor, the resolver is provided radially outward of the bearing and axially opposite the housing base from the motor stator in a direction along the central axis of rotation, The resolver includes a differential type incremental resolver and an absolute resolver, The motor stator, the absolute resolver, and the incremental resolver are arranged in this order along the central axis of rotation. Motor.

2. Each of the absolute resolver and the incremental resolver includes a resolver stator having an excitation coil and a resolver rotor provided radially inside the resolver stator, The resolver rotor of the absolute resolver is made of low carbon steel.

2. The motor according to claim 1.

3. Each of the absolute resolver and the incremental resolver includes a resolver stator having an excitation coil and a resolver rotor provided radially inside the resolver stator, The resolver rotor of the incremental resolver is made of low carbon steel and has a plurality of salient poles. The motor according to claim 1 or 2.

4. The resolver includes a resolver stator having an excitation coil and a resolver rotor provided radially inside the resolver stator, A resolver partition wall made of a non-magnetic material is provided between the resolver rotor and the resolver stator. The motor according to any one of claims 1 to 3.

5. A housing including a housing base and a housing shaft portion provided on the housing base and extending in a direction along a rotation center axis; a motor stator disposed radially outside the housing shaft portion; a motor rotor provided between the motor stator and the housing shaft portion; a bearing provided on a radially inner side of the motor rotor and configured to rotatably support the motor rotor on the housing shaft portion; a seal structure provided on an axial side of the motor rotor opposite to the housing base, the seal structure sealingly sealing a gap between the motor rotor and the housing shaft portion; a resolver that detects rotation of the motor rotor, the resolver is provided radially outward of the bearing and axially opposite the housing base from the motor stator in a direction along the central axis of rotation, The resolver includes a differential incremental resolver, The resolver includes a resolver stator having an excitation coil, and a resolver rotor provided radially inside the resolver stator, A resolver partition wall made of a non-magnetic material is provided between the resolver rotor and the resolver stator. Motor.

6. a motor partition wall provided between the motor stator and the motor rotor to separate a space in which the motor stator is disposed from a space in which the motor rotor is disposed; The motor according to any one of claims 1 to 5.

7. The outer diameter of the motor rotor is smaller than the outer diameter of the resolver rotor. The motor according to any one of claims 2 to 5.

8. The bearing is non-lubricated and includes an inner ring provided on the housing shaft portion, an outer ring provided on the motor rotor, and rolling elements provided between the inner ring and the outer ring, Of the inner ring, the outer ring, and the rolling elements, at least the rolling elements are made of ceramics. A motor according to any one of claims 1 to 7.

9. The bearing is non-lubricated and includes an inner ring provided on the housing shaft portion, an outer ring provided on the motor rotor, and rolling elements provided between the inner ring and the outer ring, The inner and outer rings are made of magnetic iron materials. A motor according to any one of claims 1 to 8.

10. A housing including a housing base and a housing shaft portion provided on the housing base and extending in a direction along a rotation center axis; a motor stator disposed radially outside the housing shaft portion; a motor rotor provided between the motor stator and the housing shaft portion; a bearing provided on a radially inner side of the motor rotor and configured to rotatably support the motor rotor on the housing shaft portion; a seal structure provided on an axial side of the motor rotor opposite to the housing base, the seal structure sealingly sealing a gap between the motor rotor and the housing shaft portion; a resolver that detects rotation of the motor rotor, the resolver is provided radially outward of the bearing and axially opposite the housing base from the motor stator in a direction along the central axis of rotation, The resolver includes a differential incremental resolver, A coupling portion made of a magnetic material is disposed between the motor stator and the resolver in a direction along the central axis of rotation. Motor.

11. an outer ring pressing portion provided on the opposite side of the housing base in the axial direction of the motor rotor and fixed to an outer ring of the bearing; and an inner ring pressing portion provided on the opposite side of the housing base in the axial direction of the housing shaft portion and fixed to an inner ring of the bearing, The seal structure has a labyrinth structure formed by the outer ring holding portion and the inner ring holding portion. A motor according to any one of claims 1 to 10.

12. The motor stator is disposed in a space closer to the atmosphere than a space in which the motor rotor is disposed. A motor according to any one of claims 1 to 11.

13. The motor rotor includes a samarium cobalt permanent magnet. A motor according to any one of claims 1 to 12.

14. a motor control circuit that supplies a drive current to an excitation coil of the motor stator based on a detection signal of the resolver; The motor control circuit excites the absolute resolver when power is turned on, and then excites the incremental resolver. The motor according to any one of claims 1 to 3.

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