Coreless motor unit and method for producing coreless motor

Abstract

[Problem] To provide a coreless motor unit in which production costs are reduced. [Solution] A coreless motor unit MU comprises a plurality of coreless motors 1 (1A, 1B) which each include a permanent magnet 11 that is disposed along the circumferential direction and a coil 12 that is disposed along the circumferential direction so as to face the permanent magnet 11, in each of which output derived from a magnetic flux Φ that is generated in the radial direction from the permanent magnet 11 and a current I that flows in the coil 12 so as to interlink with the magnetic flux Φ is obtained from a rotor 13 that is an output member connected to the permanent magnet 11, and which differ in output. Common permanent magnets 11 and coils 12 are used for the coreless motors 1A, 1B, and the number thereof corresponds to the output. The common permanent magnets 11 and coils 12 are disposed along circumferences which have prescribed radiuses R1, R2 that correspond to said number.

Description

Coreless motor unit and method of manufacturing coreless motor

[0001] The present invention relates to a method for manufacturing a coreless motor unit and a coreless motor, which aims to reduce manufacturing costs.

[0002] One known robot for transporting substrates is an articulated robot.

[0003] Articulated robots use multiple motors to independently drive shoulder joints, elbow joints, etc. When using these motors in a vacuum, for example, all parts of the motor except for the output part must be placed outside the vacuum, and the power output from the output part must be transmitted to each part via belts or links.

[0004] In such cases, in order to integrate the motor components other than the output section, the motor is configured in a multi-stage stacked structure (see, for example, Patent Document 1).

[0005] Special Table 2018-522419

[0006] In this case, the torque required varies depending on the object being driven. Generally, when configuring a motor with different torque, adjustments are made by changing the thickness of the core.

[0007] In this way, by stacking the motors in multiple stages and giving each motor different characteristics, it is possible to output torque for each driven object, and even if the number of axes of the robot is changed, the number of axes and torque can be adjusted without having to completely disassemble and reconstruct the conveying device.

[0008] However, motors are typically composed of a core, permanent magnets, and coils, and if the core thickness differs, the dimensions of the coil and magnets, as well as the molds used to make them, will also differ accordingly. As such, different motor outputs require different parts, and if the core thickness of each motor in a multi-tiered structure differs, costs will increase depending on the number of axes, making it difficult to reduce motor manufacturing costs.

[0009] The present invention has been made in light of these problems, and aims to solve these problems by using a coreless motor.

[0010] In order to achieve the above object, the present invention takes the following measures.

[0011] In other words, the coreless motor unit of the present invention is a coreless motor unit that has multiple coreless motors with different outputs, each of which has a permanent magnet arranged circumferentially and a coil arranged circumferentially opposite the permanent magnet, and is configured to obtain output from an output member connected to the permanent magnet from magnetic flux generated radially from the permanent magnet and current flowing through the coil so as to interlink with the magnetic flux, and is characterized in that each coreless motor uses a common permanent magnet and coil, and the number of coreless motors corresponding to the output are arranged along a circumference of a predetermined diameter corresponding to that number.

[0012] This eliminates the need to prepare different parts for each output and molds for making them, thereby reducing manufacturing costs.

[0013] Each coreless motor is constructed by arranging a rotor, which is an output member with a permanent magnet attached, and a shaft that rotates integrally with the rotor, on the inner periphery of a case that houses a coil. It is preferable that the cases of different diameters that make up each coreless motor are cross-sectioned, and the shafts of each coreless motor are arranged coaxially.

[0014] In this way, the height dimension does not change even if the output is different, so the axial dimension can be reduced when the coreless motor is configured in a multi-axis stacked structure, further achieving axial compactness and vibration reduction.

[0015] As a specific configuration, it is preferable that a partition wall that separates the permanent magnet from the coil is disposed on the inner periphery of the case, and that the coil is enclosed between the case and the partition wall and molded.

[0016] In this way, the partition wall can be used to pour the resin, and strength and heat dissipation properties can be ensured.

[0017] Furthermore, the method for manufacturing a coreless motor according to the present invention is characterized in that, in constructing a coreless motor comprising permanent magnets arranged along the circumferential direction and coils arranged circumferentially opposite the permanent magnets, the motor obtains output from an output member connected to the permanent magnets from magnetic flux generated radially from the permanent magnets and current flowing through the coils so as to interlink with the magnetic flux, the motor uses common permanent magnets and coils, and arranges a number of coils according to the output power along a circumference of a predetermined diameter according to that number.

[0018] In this way, when adjusting the output, it is possible to appropriately deal with differences in output using the same parts, including when using a coreless motor with a single shaft.

[0019] According to the present invention as described above, it is possible to effectively reduce the costs involved in manufacturing the coreless motor unit.

[0020] 1 is a diagram showing a substrate transfer robot to which a coreless motor unit according to an embodiment of the present invention is applied; FIG. 2 is a partially broken perspective view showing a coreless motor constituting the coreless motor unit; FIG. 3 is a longitudinal sectional view corresponding to FIG. 2; FIG. 4(a) is an exploded view of a rotor, magnet, and partition wall, FIG. 4(b) is an exploded view of a coil, case, and yoke, and FIG. 4(c) is an assembly view of a rotor, magnet, partition wall, coil, yoke, and case, which correspond to part A of FIG. 3; FIG. 4(a) is an exploded view of a rotor, magnet, and partition wall, FIG. 4(b) is an exploded view of a coil, case, and yoke, and FIG. 4(c) is an assembly view of a rotor, magnet, partition wall, coil, yoke, and case; FIG. 4(c) is a perspective view showing the relationship between a permanent magnet and a coil; FIG. 5 is an explanatory diagram showing the operating principle; FIG. 6 is a longitudinal sectional view corresponding to FIG. 6; FIG. 7 is a perspective view corresponding to FIG. 5 showing a modified example of the present invention; FIG. 8 is a diagram corresponding to FIG. 8 showing another modified example of the present invention; FIG. 10 is a diagram corresponding to part A of FIG. 10; FIG. 11(a) is an exploded view of a rotor and magnet, FIG. 11(b) is an exploded view of a coil, case, and yoke, and FIG. 11(c) is an assembly view of a rotor, magnet, coil, yoke, and case.

[0021] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0022] 1 shows an example of a substrate transfer robot 100 to which the coreless motor unit according to this embodiment is applied. This substrate transfer robot 100 has a multi-joint structure in which multiple arms 101, 102, and 103 rotate around fulcrums at so-called shoulder joints 101a, elbow joints 102a, and wrist joints 103a, and a motor unit MU that drives each of the joints 101a to 103a is incorporated into the base end of the arm 101.

[0023] The motor unit MU uses the coreless motor 1 shown in FIGS. 2 to 6, and the coreless motors 1 are assembled in a multi-stage stack as shown in FIGS. 7 and 8 (coreless motors 1A, 1B).

[0024] As shown in FIG. 2, the coreless motor 1 has permanent magnets 11 arranged along the circumferential direction and coils 12 arranged along the circumferential direction opposite the permanent magnets 11. The coreless motor 1 has a so-called direct drive structure in which an output F is obtained from an output member 13 connected to the permanent magnets 11 from magnetic flux Φ (magnetic flux density B) generated radially from the permanent magnets 11 and a current I flowing through the coils 12 so as to interlink with the magnetic flux Φ.

[0025] 5, the coreless motor 1 of this embodiment uses standard plate-shaped permanent magnet elements 11x of equal length, width, height, and shape as the permanent magnets 11, and these permanent magnet elements 11x are arranged circumferentially (strictly speaking, inside the given radius R) along a given radius R. Specifically, first magnets 11A with an S pole on the inner diameter side and an N pole on the outer diameter side and second magnets 11B with an N pole on the inner diameter side and an S pole on the outer diameter side, with only the magnetization direction being different, are arranged alternately in the circumferential direction along the given radius R.

[0026] 2 to 5, rotor 13, which is an output member, is disposed inside first magnet 11A and second magnet 11B, which are permanent magnets. Rotor 13 has a cylindrical portion 13b for attaching permanent magnet 11 to the outer periphery of thin disk portion 13a, and a boss portion 13c on the inner periphery for connecting to shaft 17. Disk portion 13a has a lightening portion 13d to reduce weight.

[0027] As shown in Figures 5 and 6(a), the coil 12 of each phase is made up of square-shaped coil elements 12x connected in the circumferential direction. A pair of vertical frames 122, 123 on either side of the coil end 121 of the square-shaped coil are configured such that, as shown in Figure 6(b), one (vertical frame 122) faces the first magnet 11A and the other (vertical frame 123) faces the second magnet 11B. When current is applied, forces f1 and f2 acting on the vertical frames 122, 123 are directed in the same direction in accordance with Fleming's rule. Because the coil 12 is fixed, a circumferential moving force F (see Figure 2) is generated relative to the first magnet 11A and the second magnet 11B. The coil 12 is composed of three phases: U, V, and W. Each phase is driven with a predetermined phase difference, generating a moving force F. The forces acting on the first magnet 11A and the second magnet 11B are transmitted to the rotor 13.

[0028] In this embodiment, the U, V, and W phases are not simply arranged sequentially in the circumferential direction, but are instead formed into a two-layer structure with an inner circumferential side and an outer circumferential side as shown in Figures 5 and 6(a). Specifically, two types of identical square-shaped inner coil elements 12x1 and outer coil elements 12x2 are formed, each with a U, V, and W phase as a group, in multiple sets. These are assembled on the inner and outer peripheries and arranged in a number corresponding to the number of sets at a predetermined radius R (strictly speaking, outside the predetermined radius R). The U phases, V phases, and W phases are connected in series and connected to a three-phase AC power supply (not shown). As shown in Figures 5 and 6(a), the square-shaped vertical frames 122, 123 of the outer coil element 12x2 are positioned next to the square-shaped vertical frames 123, 122 of the inner coil element 12x1, thereby increasing the coil density in the circumferential direction and achieving approximately twice the torque of a single-layer structure.

[0029] As described above, the coreless motor 1 is configured by arranging an integer multiple of a set of motor elements formed by the first and second magnets 11A, 11B and the U, V, and W phases in the circumferential direction.

[0030] The assembly procedure for the coreless motor 1 will be described with reference to Figures 2 to 5. In this embodiment, a yoke (back yoke) 14, a magnetic body, is used to efficiently link the magnetic flux Φ of the magnets 11 (first magnet 11A, second magnet 11B) with the coils 12. As shown in Figure 4(b), the yoke (back yoke) 14 is attached by welding to the inside of the case 10 in a circular or partial circular shape. The outer coils 12x2 are then aligned and attached along the yoke 14, and the inner coil 12x1 is then fitted in. After arranging the coils 12x1 and 12x2 in the circumferential direction, the U, V, and W phases are connected together, and the ends of the connection wires are pulled out from notches (not shown) provided at required locations on the casing 10 for current flow.

[0031] In the example of Fig. 5, the yoke 14 has a circular structure without division. However, if ease of assembly is prioritized even if it reduces motor efficiency to some extent, a four-division structure as shown in Fig. 9 or a two-division structure (not shown) may be used.

[0032] Separately, this embodiment employs a partition wall 15. In this embodiment, coreless motor 1 has arms 101, 102, and 103 (see FIG. 1) arranged in a vacuum atmosphere to transport semiconductor substrates, and has a canal structure in which the output side, i.e., the magnet 11 side, and the atmosphere side, i.e., the coil 12 side, are separated by partition wall 15, and power output from rotor 13, which is an output member, is transmitted to each of joints 101 a, 102 a, and 103 a via a transmission mechanism such as a belt or link.

[0033] To achieve this, as shown in FIG. 4( c), a partition wall 15 is attached inside the case 10 with the coil 12 sandwiched between it and the case 10. Specifically, as shown in FIG. 4( b), the lower end 10a of the case 10 has an L-shaped cross section, and as shown in FIGS. 4( a) and 4( c), the lower end 15a of the partition wall 15 abuts against the lower end 10a of the case 10, forming an annular space open upward between the case 10 and the partition wall 15. Resin 16 is poured into this space to mold the coil 12 within the space. Note that there is a space between the partition wall 15 and the magnet 11, and the rotor 13 does not come into contact with the partition wall 15 even when it rotates. Fixing the coil 12 to the case 10 with molding resin ensures the strength required to prevent deformation of the partition wall 15, coil 12, etc. even when the inner periphery is evacuated, and also ensures heat dissipation for discharging internal heat to the atmosphere. In the case where the partition wall 15 is not required for vacuum applications, a similar resin molding can be performed by temporarily using a jig equivalent to the partition wall 15 .

[0034] The partition wall 15 is made of a non-magnetic material such as CFRP or SUS so as not to interfere with the construction of the magnetic circuit.

[0035] A shaft 17 is fitted to the rotor 13, and the shaft 17 is supported by the case 10 via bearings 17x, so that a stable rotational force is output to the shaft 17.

[0036] The coreless motor unit MU shown in Figures 7 and 8 utilizes the above-mentioned coreless motor 1 and has a stacked structure in which a first coreless motor 1A that drives the elbow joint 101a and a second coreless motor 1B that drives the shoulder joint 101b are stacked.

[0037] The coreless motors 1A and 1B require different output power depending on the target motor. To achieve this, the permanent magnets 11 and coils 12 of each coreless motor 1A and 1B are made of common components with the same length, width, and height dimensions and the same shape. The number of components required is determined based on the output power. These components are arranged on the circumference of appropriate diameters R1 and R2. The commonality does not necessarily require perfect matching of the dimensions and shapes; manufacturing variations are acceptable. Furthermore, slight variations in dimensions and shapes are acceptable depending on the conditions. In Figure 7, the height of the permanent magnet 11 along the axial direction is indicated by ha, and the height (effective conductor length) of the coil 12 is indicated by hb. Because the coil ends do not contribute to torque, the axial dimension ha of the permanent magnet 11 may be equal to or less than the effective conductor length hb of the coil 12.

[0038] That is, because the first coreless motor 1A requires a higher torque than the second coreless motor 1B, it uses a greater number of sets of permanent magnets 11 and coils 12. As the number increases, the diameters must be different in order to arrange them circumferentially, so the permanent magnets 11 and coils 12 are arranged at a predetermined pitch on the circumference of circles with predetermined diameters R1 and R2 (R1 > R2) calculated to fit within that number of sets.

[0039] Since the curvature differs when the diameters R1 and R2 are different, the permanent magnet 11 and coil 12 would normally be made curved to match that curvature, but since the same parts are used between coreless motors 1A and 1B in this case, the curvature of magnet 11 and coil 12 is set to match the expected average curvature of the two axes (or, in the case of three or four axes, those axes), or they are formed approximately flat and attached to rotor 13 and case 10 (yoke 14) while changing the angle in the circumferential direction.

[0040] As a result, when comparing the coreless motors 1A and 1B as a whole, the assemblies of permanent magnets 11 and motor coils 12 have the same axial (height) dimensions ha and hb, but different radial dimensions R1 and R2. It has been confirmed that even if the curvatures are standardized in this way, the actual effect on torque is within the acceptable range of a few percent compared to when the curvature differences are strictly addressed.

[0041] When stacking the coreless motors 1A and 1B, a joint 200 is interposed between the casings 10A and 10B, and the coreless motors 1A and 1B are positioned via the joint 200. This joint 200 may be integral with either casing, or may be separate.

[0042] The shaft 17B of the coreless motor 1B is arranged coaxially on the inner periphery of the shaft 17A of the coreless motor 1A, and the shoulder joint 101a and elbow joint 101b are driven by the power output from each of the shafts 17A and 17B.

[0043] Although not explained here, if a configuration for driving the wrist joint is added, the motor will have a three- or four-layer structure, and to move the entire arm in the vertical direction, another motor that drives the arm in the vertical direction is assembled in a further layer.

[0044] In the drawing, seals for placement in a vacuum, encoders for detecting rotation, sensors, etc. are omitted.

[0045] As described above, the coreless motor unit MU of this embodiment comprises permanent magnets 11 arranged circumferentially and coils 12 arranged circumferentially opposite the permanent magnets 11, and is configured to obtain output from the rotor 13, which is an output member connected to the permanent magnets 11, from the magnetic flux Φ generated radially from the permanent magnets 11 and the current I flowing through the coils 12 so as to interlink with the magnetic flux Φ.Multiple coreless motors 1 (1A, 1B) with different outputs are provided.

[0046] Each of the coreless motors 1A and 1B uses a common permanent magnet 11 and coil 12, and the number of permanent magnets 11 and coils 12 corresponding to the output are arranged on a predetermined radius R1 or R2 corresponding to the number of permanent magnets and coils.

[0047] In this way, there is no need to prepare different parts for each output or molds for making them, and manufacturing costs can be reduced, so different outputs can be accommodated more simply and cheaply than before, and variations can be easily developed.

[0048] In this case, each coreless motor 1A, 1B is configured by arranging a rotor 13, which is an output member with a permanent magnet 11 attached, and a shaft 17 that rotates integrally with the rotor 13, on the inner periphery of a case 10 that houses a coil 12, and the cases 10A, 10B of different diameters that make up each coreless motor 1A, 1B are stacked on top of each other, and the shafts 17A, 17B of each coreless motor 1A, 1B are arranged coaxially.

[0049] In this way, the height dimensions ha and hb do not change even if the output is different, so the axial dimensions can be reduced when coreless motors 1A and 1B are configured in a multi-axis stacked structure, thereby further achieving axial compactness and vibration reduction.

[0050] Furthermore, a partition wall 15 is arranged on the inner periphery of the case 10 to separate the permanent magnet 11 from the coil 12, and the coil 12 is molded in between the case 10 and the partition wall 15.

[0051] Therefore, by using the partition wall 15 to pour the resin, molding can be performed without the resin flowing into the inner periphery of the case 10.

[0052] The manufacturing method of the coreless motor 1 according to this embodiment comprises permanent magnets 11 arranged circumferentially and coils 12 arranged circumferentially opposite the permanent magnets 11, and produces output from a rotor 13, which is an output member connected to the permanent magnets 11, from magnetic flux Φ generated radially from the permanent magnets 11 and current I flowing through the coils 12 so as to interlink with the magnetic flux Φ. In constructing the coreless motor 1, common permanent magnets 11 and coils 12 are used, and a number of coils corresponding to the output are arranged along a circumference of a predetermined radius R corresponding to that number.

[0053] Therefore, even when the coreless motor 1 is used with a single shaft or when output adjustments or changes are required, the same parts can be used appropriately.

[0054] Although one embodiment of the present invention has been described above, the specific methods and configurations of each part can be modified in various ways without departing from the spirit of the present invention.

[0055] For example, in applications other than vacuum applications, it is possible to configure a coreless motor without using a partition wall, as shown in Figures 10 and 11. In Figures 10 and 11, parts that are common to Figures 4 and 5 are given the same reference numerals, but the partition wall 15 in Figures 4 and 5 is part of the housing 10 in Figures 10 and 11.

[0056] Even in this case, the same effects as those of the above embodiment can be basically achieved.

[0057] The present invention can be used as a method for manufacturing a coreless motor unit and a coreless motor, which aims to reduce manufacturing costs.

[0058] REFERENCE SIGNS LIST 1, 1A, 1B... Coreless motor 10, 10A, 10B... Case 11, 11A, 11B... Permanent magnet (first magnet, second magnet) 12, 12x1, 12x2... Coil 13... Output member (rotor) 14... Yoke 15... Partition wall 17, 17A, 17B... Shaft I... Current R1, R2... Predetermined diameter MU... Coreless motor unit Φ... Magnetic flux

Claims

1. A coreless motor unit comprising multiple coreless motors with different outputs, each equipped with a permanent magnet arranged along the circumferential direction and a coil arranged circumferentially opposite the permanent magnet, and configured to obtain output from an output member connected to the permanent magnet from magnetic flux generated radially from the permanent magnet and current flowing through the coil so as to interlink with the magnetic flux, characterized in that each coreless motor uses the same permanent magnets and coils, and the number of coreless motors corresponding to the output are arranged along a circumference of a predetermined diameter corresponding to that number.

2. A coreless motor unit as described in claim 1, in which each coreless motor is configured by arranging a rotor, which is an output member with a permanent magnet attached, and a shaft that rotates integrally with the rotor, on the inner periphery of a case that houses a coil, and the cases that make up each coreless motor are stacked on top of each other and have different diameters, with the shafts of each coreless motor arranged coaxially.

3. A coreless motor unit as claimed in claim 1, wherein a partition wall is arranged on the inner periphery of the case to separate the permanent magnet from the coil, and the coil is molded in between the case and the partition wall.

4. A method for manufacturing a coreless motor comprising permanent magnets arranged along the circumferential direction and coils arranged circumferentially opposite the permanent magnets, and which obtains output from an output member connected to the permanent magnets from magnetic flux generated radially from the permanent magnets and current flowing through the coils so as to interlink with the magnetic flux, characterized in that common permanent magnets and coils are used and a number corresponding to the output is arranged along a circumference of a predetermined diameter corresponding to that number.

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