Motor frame and motor device

Abstract

The purpose of the present invention is to homogenize the distribution of stress applied to a stator embedded in a motor frame. A stator (21) of a motor (2) is embedded into a cylindrical main body (30) of a motor frame (3), and the cylindrical main body (30) penetrates in the extending direction of an axis (20) of a rotating shaft (23) of the motor (2). The stator (21) has a plurality of stator split bodies (6) obtained by being split in the circumferential direction of the rotating shaft (23). The thickness of the cylindrical body (30) in the inside-outside direction orthogonal to the direction in which the axial center (20) extends is defined as the wall thickness t. The angle from the reference line around the axial center (20) at an arbitrary point of the cylindrical body (30) when viewed from the direction in which the axial center (20) extends is set as an angle (theta). The thickness function is t = f (theta). The portion of the inner wall surface (5), which is an angle at which the minimum value of the waveform of the fourth-order component when the thickness function is expanded in the Fourier series, is a central portion contact portion in which the central portions of the plurality of stator split bodies (6) in the circumferential direction of the rotating shaft (23) are in contact.

Description

Technical Field

[0001] The present disclosure relates to a motor frame and a motor device. More specifically, the present disclosure relates to a motor frame having a cylindrical body having four planar outer wall surfaces and an inner wall surface in the shape of a cylindrical inner surface, and a motor device having the motor frame. Background Art

[0002] Patent document 1 discloses a method for manufacturing a stator of a brushless motor. The stator core is configured to have a plurality of split cores each having a tooth portion, and the top end of the tooth portion is arranged toward the central axis of the motor. The stator manufacturing method includes: a winding and mounting step, in which windings are wound and mounted on the teeth portion in a state where the abutment portions of the teeth portion adjacent to each other in the circumferential direction of the stator core are separated from each other; and a fixing step, in which, after the winding and mounting step, the split cores are made immovable in a state where the abutment portions of the teeth portion adjacent to each other in the circumferential direction are abutted against each other in the circumferential direction. In the fixing step, the split cores are made immovable by pressing the outer circumferential surfaces of the split cores against the inner circumferential surface of the motor housing without welding the split cores to each other in a state where the abutment portions of the teeth portion adjacent to each other in the circumferential direction are abutted against each other in the circumferential direction, so that the split cores are immovable to each other.

[0003] Thus, since the winding is wound and installed on the teeth in a state where the abutment portions of the teeth adjacent to each other in the circumferential direction are separated from each other in the winding and installing step, the effect of being able to easily wind the winding on the teeth with a high slot fill factor can be achieved.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2009-183032 Summary of the invention

[0007] Furthermore, the motor housing described in Patent Document 1 is annular in shape, and the wall thickness distribution in the circumferential direction is substantially uniform, so that the shape of the stator core embedded in the motor housing is likely to be close to a perfect circle.

[0008] However, when the motor housing is not annular and the circumferential wall thickness distribution of the motor housing is highly uneven, there is a problem that the shape of the stator core embedded in the motor housing is significantly different from a perfect circle, and the effects of the cogging torque generated in the motor are likely to be significantly manifested.

[0009] An object of the present disclosure is to provide a motor frame and a motor device that can easily achieve uniform distribution of stress applied to a stator embedded inside.

[0010] A motor frame of one embodiment of the present disclosure includes a cylindrical body. The cylindrical body passes through the direction in which the axis of the rotating shaft of the motor having a stator embedded therein extends. The stator of the motor has a plurality of stator segments, which are divided along the circumferential direction of the rotating shaft and each of which is formed with teeth extending toward the axis. The cylindrical body has four outer wall surfaces and an inner wall surface. The four outer wall surfaces are arranged in a manner to surround the rotating shaft and are in the shape of planes along the rotating shaft. The inner wall surface surrounds the rotating shaft and is in the shape of a cylindrical inner surface along the rotating shaft. The thickness of the cylindrical body in the inner and outer directions orthogonal to the direction in which the axis extends is set to the wall thickness t (mm). The angle of any point of the cylindrical body around the axis from the reference line is set to the angle θ (°). The thickness t is considered to be a function of the angle θ, and the thickness function is set to t=f(θ). The portion of the inner wall surface at which the angle of the waveform of the fourth-order component when the thickness function is Fourier series expanded takes a minimum value is a central contact portion with which the central portions of the plurality of stator divided bodies in the circumferential direction of the rotating shaft contact.

[0011] A motor device according to one aspect of the present disclosure includes the motor frame according to the above aspect and the above motor.

[0012] In the motor frame and the motor device of the present disclosure, it is easy to achieve uniform distribution of stress applied to the stator embedded inside. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is an exploded perspective view of a motor device according to an embodiment of the present disclosure.

[0014] Figure 2 It is a front view of the motor device according to one embodiment of the present disclosure.

[0015] Figure 3 This is a front view of the motor device according to one embodiment of the present disclosure, with a substrate removed.

[0016] Figure 4 This is a perspective view of a stator divided body included in a motor device according to an embodiment of the present disclosure.

[0017] Figure 5 This is a front view of a core of a motor device according to an embodiment of the present disclosure.

[0018] Figure 6 It is a perspective view of a motor frame included in the motor device according to one embodiment of the present disclosure.

[0019] Figure 7 1 is a relationship diagram between the wall thickness t and the angle θ of the motor frame according to one embodiment of the present disclosure. DETAILED DESCRIPTION

[0020] (1) Summary

[0021] Embodiments of the motor frame and the motor device of the present disclosure are described below. The embodiments described below are only a part of various embodiments of the present disclosure, and in the following embodiments, various changes can be made according to design and the like as long as the purpose of the present disclosure can be achieved.

[0022] like Figure 1 As shown, the motor frame 3 of the motor device 1 of the present disclosure includes a cylindrical body 30. The cylindrical body 30 has a stator 21 (see Figure 3 ) passes through the direction in which the axis 20 of the rotating shaft 23 of the motor 2 extends. Figure 3 As shown, the stator 21 of the motor 2 has a plurality of stator segments 6 (see Figure 4 ), the plurality of stator segments 6 are segmented along the circumferential direction of the rotating shaft 23, and each of them is formed with teeth 612 extending toward the axis 20 (see Figure 5 The cylindrical body 30 has four outer wall surfaces 4 and an inner wall surface 5 (see, for example, Figure 6 ). The four outer wall surfaces 4 are arranged in a manner to surround the rotating axis 23 and are in the form of planes along the rotating axis 23. The inner wall surface 5 surrounds the rotating axis 23 and is in the form of a cylindrical inner surface along the rotating axis 23. The thickness of the cylindrical body 30 in the inner and outer directions perpendicular to the direction in which the axis 20 extends is set to the wall thickness t (mm). The angle from the reference line around the axis 20 at any point of the cylindrical body 30 is set to the angle θ (°). Since the wall thickness t depends on the angle θ, the wall thickness t can be made a function of the angle θ. It is called the thickness function, and the thickness function is set to t=f(θ). The portion of the inner wall surface 5 at which the angle of the waveform of the fourth-order component when the thickness function is expanded by Fourier series takes a minimum value is the central contact portion for the central portions of the multiple stator segments 6 in the circumferential direction of the rotating axis 23 to contact.

[0023] In addition, if Figure 1 As shown, a motor device 1 of the present disclosure includes a motor frame 3 and a motor 2 .

[0024] In the motor frame 3 and the motor device 1 of the present disclosure, the portion of the angle at which the cylindrical body 30 is most deformed and the portion of the boundary between two adjacent stator segments 6 at which the stator 21 is most deformed are not consistent, so that it is possible to suppress the situation where the cylindrical body 30 and the stator 21 are greatly deformed. As a result, the cogging torque generated in the motor 2 can be suppressed.

[0025] (2) Details

[0026] The following is based on Figure 1 to Figure 7 A motor frame and a motor device according to an embodiment will be described.

[0027] (2.1) Overview of motor device

[0028] Figure 1 It is an exploded perspective view of the motor device 1 according to one embodiment of the present disclosure. Figure 2 It is a front view of the motor device 1 according to one embodiment of the present disclosure.

[0029] like Figure 1 , Figure 2 As shown, the motor device 1 includes a motor (electric motor) 2 and a motor frame 3 in which the motor 2 is embedded. The motor 2 is a so-called servo motor. The motor device 1 also includes a substrate 11, a position detector 121, a bracket 12, and a seal 122. The substrate 11 is a printed circuit board, and when viewed from the direction extending from the axis 20, the outer shape is circular and has a circular opening inside for the rotor 22 and the rotating shaft 23 described later to pass through, and is annular in shape like the stator 21. A protrusion 111 is formed on the substrate 11 to connect a signal line or a power line from the outside. In this embodiment, the protrusion 111 protrudes from the main body of the annular substrate 11 to the side opposite to the axis 20. In addition, a plurality of positioning holes 112 that penetrate in the direction extending from the axis 20 are formed on the substrate 11. The position detector 121 converts the displacement of the rotor of the motor 2 rotating around the axis into a digital quantity. The bracket 12 is a component for mounting the position detector on the motor frame 3. The bracket 12 is a plate-shaped member having an opening inside. The position detector 121 is mounted on the bracket 12 by an appropriate mounting method such as screwing. The bracket 12 with the position detector 121 mounted thereon is mounted on the motor frame 3 by an appropriate mounting method such as screwing.

[0030] (2.2) Motor

[0031] Figure 3 FIG. 1 is a front view of the motor device 1 according to one embodiment of the present disclosure, with the substrate 11 removed. Figure 3 As shown in FIG. 1 , the motor 2 has a stator 21, a rotor 22, and a rotating shaft 23. Figure 1 As shown, the front-to-back direction and the left-to-right direction are defined for convenience. The direction in which the axis 20 of the rotating shaft 23 extends is set as the front-to-back direction, one side of the front-to-back direction is set as the front, and the other side is set as the rear. In addition, the left and right when viewing the rear from the front are respectively set as the left and right.

[0032] like Figure 3As shown, the stator 21 is embedded in the motor frame 3 by shrink fitting. The stator 21 generates a magnetic force for rotating the rotor 22. The stator 21 has a plurality of stator segments 6. The stator segments 6 are divided along the circumferential direction of the rotating shaft 23. In the present embodiment, the stator 21 is evenly divided into 12 stator segments 6 along the circumferential direction of the rotating shaft 23.

[0033] Figure 4 It is a perspective view of the stator divided body 6 included in the motor device 1 according to one embodiment of the present disclosure.

[0034] Figure 5 FIG. 6 is a front view of the core 61 of the motor device 1 according to one embodiment of the present disclosure. Figure 4 As shown, the stator segment 6 has a core 61, a winding coil 62, and an insulator 63. Figure 5 As shown, the core 61 has a base 611, teeth 612, and a recess 615. The base 611 is connected to the base 611 of the adjacent stator segment 6. If the bases 611 of all the stator segments 6 constituting the stator 21 are connected, they form a circular ring around the axis 20. In this embodiment, the stator 21 is divided into 12 stator segments 6, so one stator segment 6 occupies a range of 30 degrees of the stator 21.

[0035] The teeth 612 extend from the base 611 toward the axis 20. The winding coil 62 is wound around the teeth 612 via an insulator 63.

[0036] The recessed portion 615 is formed on a surface of the base portion 611 in a direction opposite to the direction in which the teeth 612 protrude. In the present embodiment, the recessed portion 615 is a concave groove extending parallel to the direction in which the axis 20 extends and having an arc-shaped cross section.

[0037] like Figure 4 As shown, the insulator 63 is composed of a first insulator 631 covering the front end portion of the core 61 and a second insulator 632 covering the rear end portion of the core 61 .

[0038] The first insulator 631 is provided with a pin 64 . The pin 64 passes through a hole 112 formed in the substrate 11 .

[0039] The rotor 22 is arranged in the motor frame 3 (stator 21) so as to be rotatable relative to the stator 21. The motor 2 is an inner rotor type electric motor in which the rotor 22 is arranged closer to the rotating shaft 23 than the stator 21. The rotor 22 is surrounded by the stator core and rotated by the magnetic force generated by the stator core.

[0040] The rotating shaft 23 is a shaft fixed to the center of the rotor 22. The rotor 22 and the rotating shaft 23 rotate with the axis 20 of the rotating shaft 23 as the rotation center. The rotating shaft 23 is formed of metal and extends along the two directions of the rotor 22 and along the axis 20. The rotating shaft 23 is inserted into the opening formed in the center of the rotor 22 by shrink fitting and fixed to the rotor 22.

[0041] The rotating shaft 23 is rotatably supported by the stator 21 by the first bearing and the second bearing. The first bearing and the second bearing are rolling bearings that rotatably support the rotating shaft 23. The first bearing is embedded in the motor frame 3 and mounted on the motor frame 3. The second bearing is mounted on the bracket 12 by an appropriate mounting method such as screw fixing.

[0042] (2.3) Motor frame

[0043] (2.3.1)Tubular body

[0044] Figure 6 FIG. 1 is a perspective view of a motor frame 3 included in a motor device 1 according to an embodiment of the present disclosure. Figure 1 , Figure 6 As shown, the motor frame 3 mounts the motor 2 and holds the motor 2. The motor frame 3 includes a cylindrical body 30. The stator 21 of the motor 2 is embedded in the cylindrical body 30. The cylindrical body 30 is in a cylindrical shape that penetrates in the direction in which the axis 20 of the rotating shaft 23 of the motor 2 extends.

[0045] (2.3.2) End face

[0046] The cylindrical body 30 has two end surfaces (a first end surface 31 and a second end surface 32 ), four outer wall surfaces 4 , an inner wall surface 5 , and four connecting portions 15 .

[0047] like Figure 1 and Figure 2 As shown, the cylindrical body 30 has a first end face 31 at the front and a second end face 32 at the rear. The outer periphery of the first end face 31 is roughly quadrilateral, more specifically rectangular, and more specifically square. The inner periphery of the first end face 31 is circular. The normal line of the first end face 31 faces forward.

[0048] The outer periphery of the second end surface 32 is substantially quadrilateral, more specifically rectangular, and more specifically square. The inner periphery of the second end surface 32 is circular. The normal line of the second end surface 32 faces rearward.

[0049] The outer periphery of the first end surface 31 and the outer periphery of the second end surface 32 are substantially the same size when viewed in the direction in which the axis 20 extends. The cylindrical body 30 is square in shape when viewed in the direction in which the axis 20 extends.

[0050] The inner circumference of the first end face 31 is larger than the inner circumference of the second end face 32 when viewed in the direction extending along the axis 20. The inner circumference of the first end face 31 is substantially the same size as the outer circumference of the stator 21 of the motor 2, but the inner circumference of the second end face 32 is smaller than the outer circumference of the stator 21 of the motor 2. The stator 21 can be inserted into the inside of the cylindrical body 30 from the first end face 31, but cannot be inserted from the second end face 32.

[0051] (2.3.3)Outer wall surface

[0052] like Figure 2 , Figure 3 , Figure 6 As shown, the four outer wall surfaces 4 are arranged in a manner to surround the rotation axis 23 and are in a plane shape along the rotation axis 23. For convenience, among the four outer wall surfaces 4, the outer wall surface 4 with a normal line facing the right is set as the first outer wall surface 41, the outer wall surface 4 with a normal line facing upward is set as the second outer wall surface 42, the outer wall surface 4 with a normal line facing the left is set as the third outer wall surface 43, and the outer wall surface 4 with a normal line facing downward is set as the fourth outer wall surface 44. The first outer wall surface 41 to the fourth outer wall surface 44 are composed of planes. In addition, the first outer wall surface 41 to the fourth outer wall surface 44 may also have a portion that is not partially composed of a plane.

[0053] The first outer wall surface 41 to the fourth outer wall surface 44 are generally rectangular in shape when viewed from the front. That is, the first outer wall surface 41 is generally rectangular when viewed from the right, the second outer wall surface 42 is generally rectangular when viewed from the top, the third outer wall surface 43 is generally rectangular when viewed from the left, and the fourth outer wall surface 44 is generally rectangular when viewed from the bottom. The cylindrical body 30 is rectangular in shape when viewed from the left, the top, the left, or the bottom.

[0054] In the cylindrical body 30, an opening 33 is formed in a portion corresponding to one outer wall surface 4, for example, the outer side surface 42, which passes through in the inner and outer directions orthogonal to the front-back direction. The opening 33 allows the protrusion 111 to be inserted. The protrusion 111 of the substrate 11 passes through the opening 33 and is led out to the outside of the motor frame 3 to connect a signal line or a power line from the outside. In addition, the opening 33 is used to position the substrate 11 relative to the motor frame 3.

[0055] (2.3.4)Inner wall surface

[0056] The inner wall surface 5 surrounds the rotating shaft 23 and is in the shape of a cylindrical inner surface along the rotating shaft 23. The stator 21 of the motor 2 is embedded in the inner wall surface 5. In the first embodiment, the inner wall surface 5 is partially formed with a step portion 51 in the direction in which the axis extends (i.e., the front-rear direction) (see FIG. 2 ). Figure 1), the step portion 51 has a slightly smaller diameter than the front and rear portions thereof. The step portion 51 becomes a contact portion that contacts the motor 2 embedded inside.

[0057] A plurality of convex portions 52 are formed on the inner wall surface 5. The convex portions 52 are formed at portions corresponding to the concave portions 615 of the stator segment 6 of the stator 21 embedded therein. In the present embodiment, the convex portions 52 are convex strips extending in parallel with the direction in which the axis 20 extends and having a circular arc-shaped cross section. The cross-sectional shape of the convex portions 52 is the same as that of the concave portions 615, and the convex portions 52 are embedded in the concave portions 615.

[0058] (2.3.5) Slot

[0059] The connection portion 15 is located between two adjacent outer wall surfaces 4 among the four outer wall surfaces 4. The four connection portions 15 are provided with grooves 16 extending parallel to the axis 20 and recessed in an arch shape toward the axis 20. The configuration of the grooves 16 will be further described. In each connection portion 15, there are two geometric planes including each of the two outer wall surfaces 4 adjacent to the connection portion 15. The grooves 16 are formed so as to be recessed toward the axis 20 when viewed from the two geometric planes. The grooves 16 are grooves extending in the direction in which the axis 20 extends.

[0060] The four connecting parts 15 have grooves 16 over the entire length of the portion where the inner wall surface 5 contacts the motor 2. In this embodiment, the portion of the inner wall surface 5 where the step portion 51 is formed contacts the embedded stator 21 over the entire length in the front-rear direction.

[0061] (2.3.6) Wall

[0062] like Figure 3 As shown, at least one connection part 15 has a wall part 34. The wall part 34 is a portion of the connection part 15 where the groove 16 is not formed, and blocks the end of the groove 16 in the direction in which the axis 20 extends. In this embodiment, the wall parts 34 are formed in all four connection parts 15.

[0063] The wall portion 34 is formed at the rear end portion of the connection portion 15. Therefore, the groove 16 formed in the connection portion 15 is not open at the rear but is open at the front.

[0064] The wall portion 34 constitutes a mounting portion for mounting the motor frame 3 on an external component. Here, the external component refers to a component that is installed in the motor device 1, such as a machine tool, but is not particularly limited. A through hole 35 that penetrates in the front-to-back direction is formed in the wall portion 34, and a fixing member composed of a bolt and a nut is screwed into the through hole 35 to mount the cylindrical body 30 on an external component. When mounting the cylindrical body 30 on an external component, the fixing member is rotated using a tool such as a wrench or a screwdriver, and at this time, the operator can insert the tool into the groove 16, making it easy to perform the fastening operation of the fixing member.

[0065] By providing the mounting portion constituted by the wall portion 34, it is easy to mount a specific member on the cylindrical body 30. In particular, since the wall portion 34 is formed at a position overlapping with the groove 16 in the front-rear direction, it is easy to mount a specific member on the cylindrical body 30 without enlarging the cylindrical body 30.

[0066] Furthermore, a fixing hole 311 into which a bolt is screwed is formed in the first end surface 31 , and the bracket 12 is attached by the bolt screwed into the fixing hole 311 .

[0067] (3) Thickness of the cylindrical body

[0068] The wall thickness of the cylindrical body 30 is described. First, the thickness of the cylindrical body 30 in the inner and outer directions perpendicular to the front-back direction is defined as the wall thickness t (mm). The angle of any point of the cylindrical body 30 around the axis 20 from the reference line 10 is defined as the angle θ (°). In addition, the reference line 10 starts from the axis 20, is perpendicular to the axis 20 and is along the direction relative to the axis 20 toward the protrusion 111 (refer to Figure 2 ) direction. In addition, the units of thickness t and angle θ are for convenience, and the unit of thickness t may not be (mm), and the unit of angle θ may not be (°). In addition, referring to Figure 2 , Figure 3 , θ increases in the counterclockwise direction with the axis 20 as the center.

[0069] Next, the thickness function is set to t=f(θ). Figure 7 1 is a relationship diagram between the wall thickness t and the angle θ of the motor frame according to one embodiment of the present disclosure. Figure 7 The reference numeral 71 in the figure represents a t-θ relationship diagram in this embodiment. Figure 7 In the figure, the thickness t is the thickness of the central portion of the portion in contact with the stator 21 embedded in the inner portion in the direction in which the axis 20 extends, and the angle is represented by θ (°). The cylindrical body 30 is substantially square in the direction in which the axis 20 extends, and the grooves 16 are formed in the four connecting portions 15, so that Figure 7 t-θ relationship diagram shown in the figure numeral 71.

[0070] Perform Fourier series expansion on the thickness function. Figure 7 The waveform of the fourth-order component of the result of Fourier series expansion is indicated by the reference numeral 72. As described above, the cylindrical body 30 is roughly square in the direction in which the axis 20 extends, so it can be considered that the waveform of the fourth-order component of the result of Fourier series expansion best represents the tendency of the relationship between the wall thickness t and the angle θ throughout the entire cylindrical body 30. That is, from the waveform of the fourth-order component of the result of Fourier series expansion, it can be seen that the deformation of the cylindrical body 30 and the stator 21 is greatly affected when the stator 21 is embedded in the interior of the cylindrical body 30. According to Figure 7 In the figure 72, when considering the deformation of the entire cylindrical body 30, the part of the cylindrical body 30 where the wall thickness t is the smallest and the most easily deformed is the part where the angle θ is 90°, 180°, 270°, and 360°. Figure 7 The relationship between the wall thickness t and the angle θ shown in the figure mark 71 is that the parts where the angle θ takes the minimum value are eight parts where the angle θ is 45°, 90°, 135°, 180°, 225°, 270°, 315°, and 360°. However, it can be considered that the cylindrical body 30 is most greatly deformed at the minimum value of the fourth-order component of the result of the Fourier series expansion, that is, the parts where the angle θ is 90°, 180°, 270°, and 360°.

[0071] In the present embodiment, the central portion (recess 615) of the plurality of stator segments 6 in the circumferential direction of the rotating shaft 23 is located at the portion of the inner wall surface 5 where the angle of the waveform of the fourth-order component when the thickness function is Fourier series expanded takes a minimum value (the portion where the angle θ is 90°, 180°, 270°, and 360°). The stator 21 embedded in the cylindrical body 30 is composed of a plurality of stator segments 6, and is not welded to the cylindrical body 30 but embedded in the cylindrical body 30 by shrink fit. In addition, the two adjacent stator segments 6 are not welded to each other and are not fixed to each other, so it can be considered that in the stator 21, the boundary portion of the two adjacent stator segments 6 is the most deformed portion.

[0072] Therefore, if the portions of the cylindrical body 30 where the angle θ is 90°, 180°, 270°, and 360° are most deformed and the portions of the boundaries of the two adjacent stator segments 6 where the stator 21 is most deformed are consistent, there is a concern that the cylindrical body 30 and the stator 21 are greatly deformed when the stator 21 is embedded in the cylindrical body 30. Therefore, in the present embodiment, it is designed that the boundaries of the stator segments 6 where the stator 21 is most deformed are not located at the portions where the angle θ is 90°, 180°, 270°, and 360°, and the circumferential center portion (recess 615) of the stator segments 6 is located at the above-mentioned portions.

[0073] Thus, since the portions of the cylindrical body 30 where the angle θ is 90°, 180°, 270°, and 360° are most deformed and the portions of the boundaries of the two adjacent stator segments 6 where the stator 21 is most deformed are not consistent, it is possible to suppress the situation where the cylindrical body 30 and the stator 21 are greatly deformed. As a result, it is possible to suppress the deformation of the cylindrical body 30 and the stator 21 so that the outer shapes of the inner wall surface 5 of the cylindrical body 30 and the stator 21 observed from the direction in which the axis 20 extends are close to a perfect circle, and the cogging torque generated in the motor 2 can be suppressed.

[0074] In addition, in the present embodiment, the stator 21 is composed of 12 stator segments 6. Therefore, when the central portion of the stator segment 6 in the circumferential direction is located at the portion where the angle θ is 90°, 180°, 270°, and 360°, the boundaries of the stator segment 6 where the stator 21 is most deformed are located at four locations where the angle θ is 45°, 135°, 225°, and 315°. However, by forming the grooves 16 extending parallel to the axis 20 and arched toward the axis 20 in the four connecting portions 15 at the angles θ of 45°, 135°, 225°, and 315°, the rigidity of the cylindrical body 30 in this portion is improved. As a result, the deformation of the cylindrical body 30 and the stator 21 can be further suppressed, thereby suppressing the cogging torque generated in the motor 2.

[0075] Furthermore, since the convex portion 52 is formed on the inner wall surface 5 of the cylindrical body 30 and the concave portion 615 into which the convex portion 52 is fitted is formed in the stator segment 6 , the stator segment 6 can be easily and reliably positioned relative to the cylindrical body 30 .

[0076] (4) Modification

[0077] The shape of the substrate 11 is not limited. In addition, the substrate 11 may not be fixed to the stator 21, and may not necessarily be provided in the motor device 1. The protrusion 111 may not protrude from the main body of the substrate 11 to the side opposite to the axis 20, and the protruding direction of the protrusion 111 is not limited. In addition, the protrusion 111 may not be formed on the substrate 11. The number of holes 112 formed in the substrate 11 is not limited. In addition, the hole 112 may not be formed in the substrate 11.

[0078] The position detector 121 , the bracket 12 , and the seal 122 may be arbitrary structures, and the motor device 1 may not include these structures.

[0079] The position detector 121 may be, for example, a slip ring or the like, and is not limited to a rotary encoder.

[0080] The motor 2 is not limited to a servo motor.

[0081] The rotor 22 is not limited to a surface magnet type rotor.

[0082] The opening 33 may be an arbitrary structure and may not be formed in the cylindrical body 30 .

[0083] The inner wall surface 5 may also have a portion that does not partially constitute the inner surface of the cylinder. In addition, the contact portion of the inner wall surface 5 that contacts the stator 21 of the motor 2 embedded inside may also extend over the entire length in the direction in which the axis extends (i.e., the front-to-back direction). In addition, the contact portion of the inner wall surface 5 that contacts the stator 21 of the motor 2 embedded inside may not be constituted by the step portion 51. That is, the portion in front of the contact portion and the portion in the back of the contact portion may also be on the same surface extending in the front-to-back direction as the contact portion.

[0084] The groove 16 does not need to be formed over the entire length of the portion where the contact portion is located in the front-rear direction.

[0085] The number of stator divided bodies 6 is not limited to 12. In addition, the stator divided bodies 6 may not necessarily be divided equally in the circumferential direction of the rotating shaft 23 .

[0086] The shape of the recessed portion 615 is not limited to the arc-shaped cross section. The recessed portion 615 may not be provided in the core 61 .

[0087] There is no limitation on the number of members constituting the insulator 63. Insulating paper may be used instead of the insulator, or the insulator may be used instead of the insulating paper.

[0088] The shape of the convex portion 52 is not limited to the arc-shaped cross section. The convex portion 52 may not be provided on the inner wall surface 5 .

[0089] The grooves 16 do not need to be formed in all of the four connecting portions 15 , and the number of the grooves 16 is not limited. In addition, the grooves 16 may not necessarily be formed in the motor frame 3 .

[0090] The wall portion 34 may not be formed on all of the four connecting portions 15, and the number of the wall portions 34 is not limited. In addition, the wall portion 34 may be formed on the front end of the connecting portion 15. In addition, the wall portion 34 may not necessarily be formed on the motor frame 3.

[0091] (5) Summary

[0092] As described above, the motor frame (3) of the first embodiment includes a cylindrical body (30). The cylindrical body (30) passes through the direction in which the axis (20) of the rotating shaft (23) of the motor (2) having the stator (21) embedded therein extends. The stator (21) of the motor (2) includes a plurality of stator segments (6), which are segmented along the circumferential direction of the rotating shaft (23) and each of which is provided with teeth (612) extending toward the axis (20). The cylindrical body (30) includes four outer wall surfaces (4) and an inner wall surface (5). The four outer wall surfaces (4) are arranged in a manner surrounding the rotating shaft (23) and are in the form of planes respectively along the rotating shaft (23). The inner wall surface (5) surrounds the rotating shaft (23) and is in the form of a cylindrical inner surface along the rotating shaft (23). The thickness of the cylindrical body (30) in the inner and outer directions orthogonal to the direction in which the axis (20) extends is set as the wall thickness t (mm). The angle of any point of the cylindrical body (30) around the axis (20) from the reference line is set to angle θ (°). The thickness function is set to t = f (θ). The portion of the inner wall surface (5) at which the angle of the waveform of the fourth-order component when the thickness function is expanded by Fourier series takes a minimum value corresponds to the central portion (recess (615)) of the plurality of stator segments (6) in the circumferential direction of the rotating shaft (23).

[0093] In the first embodiment, since the portion of the angle at which the cylindrical body (30) is most deformed and the portion of the boundary between two adjacent stator segments (6) at which the stator (21) is most deformed are not consistent, it is possible to suppress the cylindrical body (30) and the stator (21) from being greatly deformed. As a result, the cogging torque generated in the motor (2) can be suppressed.

[0094] The second solution can be realized by combining with the first solution. In the second solution, the cylindrical body (30) further comprises four connecting portions (15) located between adjacent outer wall surfaces (4) among the four outer wall surfaces (4). The four connecting portions (15) are provided with grooves (16) extending parallel to the axis (20) and recessed in an arch shape toward the axis (20).

[0095] In the second aspect, the rigidity of the cylindrical body (30) is improved by the groove (16), and the cogging torque generated in the motor (2) can be further suppressed.

[0096] The third solution can be realized by combining with the first solution or the second solution. In the third solution, the motor (2) has an insulator (63) and a printed circuit board. The insulator (63) is mounted on the stator (21). The printed circuit board is mounted on the insulator (63) in a state of being positioned by a pin (64) formed on the insulator (63), and has a protrusion (111) protruding to the side opposite to the rotating shaft (23). A recess or opening (33) is formed in the motor frame (3) into which the protrusion (111) can be inserted.

[0097] In the third aspect, the stator segment (6) can be easily and reliably positioned relative to the cylindrical body (30).

[0098] The fourth embodiment can be realized by combining with any one of the first to third embodiments. In the fourth embodiment, a plurality of protrusions (52) are formed on the inner wall surface (5) of the cylindrical body (30). A plurality of stator segments (6) are formed with recesses (615) into which the plurality of protrusions (52) are respectively inserted.

[0099] In the fourth aspect, the stator segment (6) can be easily and reliably positioned relative to the cylindrical body (30).

[0100] The fifth aspect can be realized by combining with any one of the first to fourth aspects. In the fifth aspect, the motor device (1) includes the motor frame (3) of any one of the first to fourth aspects, and a motor (2).

[0101] In the fifth embodiment, since the portion of the cylindrical body (30) where the deformation is the greatest and the portion of the boundary between two adjacent stator segments (6) where the deformation is the greatest, the cylindrical body (30) and the stator (21) where the deformation is the greatest do not coincide, it is possible to suppress the cylindrical body (30) and the stator (21) from being greatly deformed. As a result, it is possible to suppress the cogging torque generated in the motor (2).

[0102] Industrial Applicability

[0103] In the motor frame and the motor device disclosed in the present invention, it is easy to seek uniform stress distribution applied to the stator embedded inside. As a result, the generation of cogging torque of the motor can be suppressed. That is, the motor frame and the motor device disclosed in the present invention are useful in industry.

[0104] Description of Reference Numerals

[0105] 1. Motor device; 10. Base line; 111. Protrusion; 15. Connecting portion; 16. Groove; 2. Motor; 20. Axis; 21. Stator; 23. Rotating axis; 3. Motor frame; 30. Cylindrical body; 33. Opening; 4, 41, 42, 43, 44, Outer wall surface; 5, Inner wall surface; 6. Stator segment; 612, Tooth; 615, Recess; 63, 631, 632, Insulator; 64, Pin.

Claims

1. A motor frame, wherein: The motor frame includes a cylindrical body that penetrates in a direction in which the axis of a rotating shaft of a motor having a stator embedded therein extends. The stator of the motor includes a plurality of stator divided bodies, each of which is divided along the circumferential direction of the rotating shaft and has teeth extending toward the rotating shaft. The cylindrical body has: four outer wall surfaces arranged to surround the rotation axis and in planes respectively along the rotation axis; and an inner wall surface which surrounds the rotation axis and is in the shape of a cylindrical inner surface along the rotation axis, When the thickness of the cylindrical body in the inner and outer directions perpendicular to the direction in which the axis extends is defined as the wall thickness t, the angle of any point of the cylindrical body from the reference line around the axis when viewed from the direction in which the axis extends is defined as the angle θ, and the thickness function is defined as t=f(θ), The portion of the inner wall surface at which the angle of the waveform of the fourth-order component when the thickness function is expanded in Fourier series takes a minimum value is the central contact portion where the central portions of the plurality of stator segments contact each other in the circumferential direction of the rotating shaft. The unit of the wall thickness t is mm, and the unit of the angle θ is rad.

2. The motor frame according to claim 1, wherein: The cylindrical body further comprises four connecting portions located between adjacent outer wall surfaces among the four outer wall surfaces. The four connection portions are formed with grooves extending parallel to the axis and recessed in an arch shape toward the axis.

3. The motor frame according to claim 1, wherein: The motor has: an insulator mounted on the stator; as well as a printed circuit board mounted on the insulator in a state of being positioned by pins formed on the insulator, and having a protrusion protruding to the side opposite to the rotation axis, The motor frame is formed with a recess or an opening into which the protrusion can be inserted.

4. The motor frame according to claim 1, wherein: A plurality of convex portions are formed on the inner wall surface of the cylindrical body. The plurality of stator divided bodies are formed with recessed portions into which the plurality of convex portions are respectively fitted.

5. A motor device, wherein: The motor device has: The motor frame according to any one of claims 1 to 4; and The motor.

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