CN116547461A

CN116547461A - Direct drive motor

Info

Publication number: CN116547461A
Application number: CN202180081045.4A
Authority: CN
Inventors: 丸山正幸; 福山健一; 田口俊文
Original assignee: NSK Ltd
Current assignee: NSK Ltd
Priority date: 2020-12-07
Filing date: 2021-11-24
Publication date: 2023-08-04
Also published as: JPWO2022124073A1; WO2022124073A1

Abstract

The direct drive motor includes a fixed shaft, a bearing portion in which an inner ring is fitted to the fixed shaft, an output shaft in which an outer ring of the bearing portion is fitted, a1 st restricting member disposed in a1 st direction of the inner ring, a2 nd restricting member disposed in the 1 st direction of the outer ring, and a motor portion. The fixed shaft has a1 st main body part for the inner ring to be embedded, a1 st abutting part abutting against the end face of the inner ring in the 2 nd direction, a base abutting part abutting against the base, and a1 st internal thread hole for the 1 st fastening piece to be in threaded connection. The output shaft has a2 nd main body part into which the outer ring is fitted, a2 nd abutting part abutting against the 2 nd end face of the outer ring, a cylindrical mounting part in which the 1 st end face protrudes in the 1 st direction from the 2 nd restricting member, and a2 nd female screw hole into which the 2 nd fastener is screwed. The 1 st restricting member is fastened to the 1 st main body portion and abuts against the 1 st end face of the inner ring, and the 2 nd restricting member is fastened to the 2 nd main body portion and abuts against the 1 st end face of the outer ring.

Description

Direct drive motor

Technical Field

The present disclosure relates to direct drive motors.

Background

The direct drive motor is a motor that directly transmits the generated power to the object without a reduction mechanism. Examples of the object include a table on which a workpiece is placed, and an arm for gripping the workpiece. The direct drive motor of patent document 1 includes: a base having a ring shape and fastened to the base by a fastener; a fixed shaft which is embedded in the inner peripheral surface of the base; a bearing fitted to the outer peripheral side of the fixed shaft; a connecting member fitted to the outer peripheral side of the bearing; an output shaft fitted to the connection member; and a motor unit that applies torque to the output shaft.

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open No. 2002-2336100

Disclosure of Invention

Problems to be solved by the invention

In the direct drive motor of patent document 1, a fixed shaft is fixed to a base via a base. The output shaft is supported by the fixed shaft via a connecting member. According to such a structure, rigidity for supporting the fixed shaft and the output shaft may be lowered. When the output shaft rotates, the output shaft is liable to vibrate in the radial direction, so-called "chatter".

The present disclosure has been made in view of the above, and an object thereof is to provide a direct drive motor capable of suppressing shake of an output shaft.

Solution for solving the problem

In order to achieve the above object, a direct drive motor according to an aspect of the present disclosure includes: a fixed shaft which is cylindrical; a bearing part, the inner ring of which is embedded on the outer circumferential surface of the fixed shaft; an output shaft having a cylindrical shape, wherein an outer ring of the bearing portion is fitted to an inner peripheral surface of the output shaft; a1 st restriction member disposed in a1 st direction in an axial direction parallel to an axis of the output shaft with respect to the inner ring; a2 nd restriction member disposed in the 1 st direction with respect to the outer ring; and a motor unit that applies torque to the output shaft. The fixed shaft has: a1 st main body part which is cylindrical and is used for embedding the inner ring; a1 st contact portion which is cylindrical, extends from the 1 st main body portion in a2 nd direction opposite to the 1 st direction, and contacts an end surface of the inner ring in the 2 nd direction; a base contact portion extending from the 1 st contact portion in the 2 nd direction, the 2 nd end face being in contact with a base; and a1 st internal screw hole provided in the end surface of the base abutting portion in the 2 nd direction, the 1 st fastener for fastening the base abutting portion and the base being screwed into the 1 st internal screw hole. The output shaft has: a2 nd main body part which is cylindrical and is used for embedding the outer ring; a2 nd contact portion having a cylindrical shape, located closer to the 2 nd direction than the 2 nd main body portion, and being in contact with an end surface of the outer ring in the 2 nd direction; a mounting portion having a tubular shape and extending from an outer peripheral portion of the 2 nd main body portion in the 1 st direction, wherein an end surface in the 1 st direction protrudes in the 1 st direction from the 2 nd restricting member; and a2 nd internal screw hole provided in the end surface of the mounting portion in the 1 st direction, wherein a2 nd fastener for fastening the mounting portion and the object is screwed into the 2 nd internal screw hole. The 1 st restriction member is fastened to the 1 st end surface of the 1 st main body portion and abuts against the 1 st end surface of the inner ring. The 2 nd restricting member is fastened to the 1 st end face of the 2 nd main body portion and abuts against the 1 st end face of the outer ring.

According to the direct drive motor of the present disclosure, there are no components interposed between the base and the fixed shaft, between the fixed shaft and the bearing portion, and between the bearing portion and the output shaft. In other words, the fixed shaft is fastened by the 1 st fastener that is screw-coupled with the 1 st female screw hole. Thus, the fixed shaft is directly supported by the base. The inner ring of the bearing part is embedded in the 1 st main body part of the fixed shaft. Thus, the bearing portion is directly supported by the fixed shaft. The 2 nd main body part of the output shaft is embedded in the outer ring of the bearing part. Thus, the output shaft is directly supported by the bearing portion. As described above, the rigidity of supporting the output shaft is high. Therefore, the shake of the output shaft is suppressed when the output shaft rotates. Further, if the number of parts interposed between the fixed shaft and the output shaft increases, there is a possibility that the output shaft is eccentric with respect to the fixed shaft due to the influence of assembly tolerance, in other words, there is a possibility that the workpiece cannot be conveyed with high accuracy. However, according to the direct drive motor of the present disclosure, the member interposed between the fixed shaft and the output shaft is only a bearing portion. Thus, the influence of assembly tolerance is small, and concentricity of the output shaft with respect to the fixed shaft is high. This enables the workpiece to be conveyed with high accuracy. The bearing portion is positioned in the axial direction by abutting against the 1 st abutting portion of the fixed shaft. The 2 nd contact portion of the output shaft is in contact with the bearing portion and is positioned in the axial direction. Thus, regarding the positioning of the output shaft with respect to the axial direction of the fixed shaft, the member interposed between the fixed shaft and the output shaft is also only the bearing portion. This reduces the influence of assembly tolerances, and can set the position (height) of the object fixed to the output shaft to a desired position (height). For this reason, the workpiece can be conveyed with high accuracy. In addition, the 1 st restriction member and the 2 nd restriction member are abutted against the inner ring or the outer ring. This suppresses the axial movement of the output shaft and the change in the position of the object.

As a desirable aspect of the direct drive motor, the motor section has: a rotor fitted to an outer peripheral surface of the output shaft; and a stator surrounding an outer peripheral side of the rotor. And a stator support portion that extends radially outward from the base contact portion and supports the stator is fastened to an outer peripheral side of the base contact portion.

The stator sometimes vibrates due to magnetic attraction and repulsion forces generated between the stator and the rotor. In addition, if the stator is supported by the fixed shaft, vibrations of the stator are transmitted to the fixed shaft, and a shake may occur in the output shaft. In the direct drive motor of the present disclosure, the stator is supported by a stator support portion fastened to the stationary shaft. As a result, if the stator vibrates, the vibration is absorbed by the stator support portion, and is less likely to be transmitted to the fixed shaft. Therefore, the output shaft is prevented from being dithered due to the vibration of the stator.

As a desirable mode of the direct drive motor according to one mode, the inner shape and the outer shape of the 2 nd main body portion are circular shapes centering on the axis.

Conventionally, in order to fix other members to the outer peripheral surface of the output shaft, the outer peripheral surface of the output shaft may be subjected to milling or the like. In such processing, an internal stress is generated in the rotary shaft, and the inner peripheral surface of the rotary shaft is deformed. If the inner circumferential surface of the rotary shaft is non-circular, the tightening force applied to the outer ring by the fitting becomes uneven in the circumferential direction of the outer ring, which causes rattling of the output shaft. On the other hand, in the output shaft of the present disclosure, the inner shape and the outer shape of the 2 nd main body portion are circular. Thus, the tightening force applied to the outer ring by the fitting acts uniformly in the circumferential direction of the outer ring. Therefore, the shake of the output shaft is suppressed when the output shaft rotates.

As a desirable mode of the direct drive motor according to one mode, the inner shape and the outer shape of the 1 st main body portion are circular shapes centering on the axis.

The fastening force applied to the inner ring by the fitting of the 1 st main body portion acts uniformly in the circumferential direction of the inner ring. Therefore, the shake of the bearing portion with respect to the fixed shaft is suppressed. Further, the shake of the output shaft supported by the bearing portion is also suppressed.

As a desirable mode of the direct drive motor according to one mode, the 1 st internal thread hole is disposed radially inward of the rolling surface of the inner ring. The 2 nd internal thread hole is arranged at a position radially outside the rolling surface of the outer ring.

When the 1 st fastener is screwed into the 1 st female screw hole, the fixed shaft is deformed so that the aperture of the 1 st female screw hole increases. If the 1 st internal thread hole overlaps the rolling surface of the inner ring in the axial direction, the rolling surface of the inner ring is deformed, and the rolling element does not smoothly rotate. However, the 1 st internally threaded hole of the present disclosure is disposed radially inward of the rolling surface of the inner ring and is separated from the rolling surface of the inner ring. Thus, the rolling surface of the inner ring is hardly deformed. Likewise, the 2 nd internally threaded bore is spaced from the rolling surface of the outer race. Thus, the rolling surface of the outer ring is hardly deformed. As described above, the rolling elements smoothly roll on the rolling surface, and the output shaft smoothly rotates.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the direct drive motor of the present disclosure, the shake of the output shaft is suppressed when the output shaft rotates, and the workpiece can be stably conveyed.

Drawings

Fig. 1 is a cross-sectional view schematically showing an example of the overall structure of a direct drive motor according to embodiment 1.

Fig. 2 is a cross-sectional view of a portion of the direct drive motor of fig. 1 enlarged.

Fig. 3 is a bottom view of the direct drive motor according to embodiment 1 as seen from the 2 nd direction.

Fig. 4 is a plan view of the direct drive motor of embodiment 1 as viewed from the 1 st direction.

Detailed Description

The mode for carrying out the invention is described in detail with reference to the accompanying drawings. The present invention is not limited to the following description. The constituent elements described below include elements that can be easily understood by those skilled in the art, and substantially the same elements. The following components can be appropriately combined.

Fig. 1 is a cross-sectional view schematically showing an example of the overall structure of a direct drive motor according to embodiment 1. Fig. 2 is a cross-sectional view of a portion of the direct drive motor of fig. 1 enlarged. Fig. 3 is a bottom view of the direct drive motor according to embodiment 1 as seen from the 2 nd direction. Fig. 4 is a plan view of the direct drive motor of embodiment 1 as viewed from the 1 st direction.

As shown in fig. 1, a direct drive motor 100 according to embodiment 1 is a motor that generates power for conveying a workpiece (not shown). The direct drive motor 100 of embodiment 1 is configured such that a base 110 is disposed on one side of an axis AX of an output shaft 3. The direct drive motor 100 is fixed to a base 110. Further, the direct drive motor 100 is provided with a table 120 on the other side of the axis AX of the output shaft 3. The table 120 is mounted to the direct drive motor 100. The direct drive motor 100 rotates the table 120 about the axis AX, and conveys a workpiece (not shown) placed on the table 120.

In addition, the direct drive motor 100 of the embodiment is exemplified as the mounting table 120, but the direct drive motor of the present disclosure is not limited to this. For example, the direct drive motor of the present disclosure may be used as a servomotor that is used as a drive source for driving the arm. In addition, the direct drive motor of the present disclosure may be used in an inspection apparatus, a machine tool, a semiconductor manufacturing apparatus, and the like.

The direct drive motor 100 includes a fixed shaft 1, a bearing portion 2, an output shaft 3, a1 st restricting member 4, a2 nd restricting member 5, a1 st cover member 6, a stator support member 7, a motor portion 8, and a2 nd cover member 9. In the following description, a direction parallel to the axis AX will be referred to as an axial direction. The direction in which the table 120 is disposed in the axial direction as viewed from the direct drive motor 100 is referred to as A1 st direction A1. The direction in which the base 110 is arranged as seen from the direct drive motor 100 is referred to as the 2 nd direction A2.

The fixed shaft 1 is a cylindrical member having a center extending in the axial direction. As shown in fig. 2, the stationary shaft 1 includes: the 1 st main body 10 having an outer peripheral surface fitted with inner rings 25 and 26 of the bearing 2; a1 st contact portion 11 extending from the 1 st main body portion 10 in the 2 nd direction A2; a base contact portion 12 extending from the 1 st contact portion 11 in the 2 nd direction A2; and a protruding portion 13 protruding from the 1 st main body portion 10 in the 1 st direction. That is, the stationary shaft 1 is a member in which the 1 st main body 10, the 1 st contact portion 11, the base contact portion 12, and the protruding portion 13 are integrally formed. In fig. 2, auxiliary lines (two-dot chain lines) are drawn to clarify the respective portions of the 1 st main body 10, the 1 st contact 11, the base contact 12, and the protruding portion 13.

The 1 st main body 10 has a cylindrical shape centered on the axis AX. That is, the outer peripheral surface 10a and the inner peripheral surface 10b of the 1 st main body 10 are circular with the axis AX as a center when viewed from the axis AX direction (see fig. 3). The length of the 1 st main body portion 10 in the axial direction is the same as the length of the bearing portion 2 in the axial direction. The end face 10c of the 1 st main body 10 in the 1 st direction A1 is provided with a plurality of female screw holes 10d arranged at equal intervals in the circumferential direction. The thickness T1 (see fig. 1) from the outer peripheral surface 10a to the inner peripheral surface 10b of the 1 st main body 10.

The 1 st contact portion 11 has an outer diameter larger than that of the 1 st main body portion 10. That is, the 1 st contact portion 11 protrudes radially outward from the outer peripheral surface 10a of the 1 st main body portion 10. The end face 11a in the 1 st direction A1 of the 1 st contact portion 11 contacts the end face 26a in the 2 nd direction A2 of the inner race 26 of the bearing portion 2.

The base contact portion 12 includes: a large diameter portion 14 having an outer diameter larger than that of the 1 st contact portion 11; and a protrusion 15 protruding from an end surface 14a of the large diameter portion 14 in the 2 nd direction A2 toward the 2 nd direction A2.

The end face 14a in the 2 nd direction A2 of the large diameter portion 14 is provided with a plurality of outer circumferential female screw holes 14b and a plurality of inner circumferential female screw holes 14c, the plurality of outer circumferential female screw holes 14b being arranged on the outer circumferential side of the protruding portion 15, and the plurality of inner circumferential female screw holes 14c being arranged on the inner circumferential side of the protruding portion 15. As shown in fig. 3, the outer circumferential internal thread holes 14b and the inner circumferential internal thread holes 14c are provided in plural at equal intervals in the circumferential direction.

As shown in fig. 3, the protrusion 15 is annular when viewed from the axial direction. As shown in fig. 2, the end face 15a of the protrusion 15 in the 2 nd direction A2 is a flat face. The end surface 15a of the protrusion 15 in the 2 nd direction A2 abuts on a surface (mounting surface) of the base 110 facing the 1 st direction A1.

A1 st female screw hole 15b is provided in an end face 15a of the protrusion 15 in the 2 nd direction A2. The 1 st female screw holes 15b are provided in plural at equal intervals in the circumferential direction (see fig. 3). The 1 st fastener 201 penetrating the base 110 is screwed into the 1 st female screw hole 15b. Thereby, the protruding portion 15 (the base abutting portion 12) is fastened to the base 110, and the fixed shaft 1 is fixed to the base 110.

The end surface 15a of the protrusion 15 in the 2 nd direction A2 is located closer to the 2 nd direction A2 than the 1 st cover member 6 and the stator support member 7. That is, the 1 st cover member 6 and the stator support member 7 do not abut on the base 110.

As shown in fig. 2, the protruding portion 13 protrudes from the inner peripheral side of the end surface 10c of the 1 st main body portion 10 in the 1 st direction A1 to the 1 st direction A1. The outer peripheral surface of the protruding portion 13 is circular when viewed from the axial direction.

The bearing section 2 includes a1 st bearing 21 and A2 nd bearing 22 arranged in the 2 nd direction A2 with respect to the 1 st bearing 21. The 1 st bearing 21 and the 2 nd bearing 22 are angular contact ball bearings with combined back surfaces. The 1 st bearing includes an outer ring 23, an inner ring 25, and a plurality of rolling elements 27 arranged between the outer ring 23 and the inner ring 25. The 2 nd bearing includes an outer ring 24, an inner ring 26, and a plurality of rolling elements 28 disposed between the outer ring 24 and the inner ring 26. The rolling surfaces of the inner rings 25 and 26 are located radially outward of the 1 st female screw hole 15b of the fixed shaft 1 (see virtual line L in fig. 2). In other words, the 1 st female screw hole 15b of the fixed shaft 1 is located radially inward of the rolling surfaces of the inner rings 25 and 26. That is, the 1 st internally threaded hole 15b and the rolling surfaces of the inner ring 25 and the inner ring 26 do not overlap in the axial direction.

The output shaft 3 is a cylindrical member. The output shaft 3 includes: a2 nd main body portion 30 having a cylindrical shape and fitted to the outer ring 23 and the outer ring 24; a2 nd contact portion 31 extending from the 2 nd main body portion 30 in the 2 nd direction A2; and a mounting portion 32 having a tubular shape and extending from the outer peripheral portion of the 2 nd main body portion 30 in the 1 st direction A1. That is, the output shaft 3 is a cylindrical member. The output shaft 3 is a member in which the 2 nd main body portion 30, the 2 nd contact portion 31, and the cylindrical mounting portion 32 are integrally formed.

The 2 nd main body portion 30 is cylindrical around the axis AX. That is, the outer peripheral surface 30a and the inner peripheral surface 30b of the 2 nd body portion 30 are circular about the axis AX when viewed from the axial direction (see fig. 4). As shown in fig. 2, the length of the 2 nd main body portion 30 in the axial direction is the same as the length of the bearing portion 2 in the axial direction. The end face 30c of the 2 nd main body 30 in the 1 st direction A1 is provided with a plurality of female screw holes 30d arranged at equal intervals in the circumferential direction. The outer peripheral surface 30a of the 2 nd main body 30 includes an annular protruding portion 30e protruding radially outward from the end in the 1 st direction A1. The protruding portion 30e is an axial positioning portion of the rotor 81. The thickness T2 (see fig. 1) from the outer peripheral surface 30a to the inner peripheral surface 30b of the 2 nd main body 30.

The inner diameter of the 2 nd abutment portion 31 is smaller than the inner diameter of the 2 nd main body portion 30. That is, the 2 nd contact portion 31 protrudes radially inward from the inner peripheral surface 30b of the 2 nd main body portion 30. The end face 31a in the 1 st direction A1 of the 2 nd abutting portion 31 abuts against the end face 24a in the 2 nd direction A2 of the outer ring 24.

As shown in fig. 4, the mounting portion 32 is annular when viewed from the axial direction. As shown in fig. 2, the end face 32a of the mounting portion 32 in the 1 st direction A1 is an abutment surface against the table 120. The attachment portion 32 protrudes in the 1 st direction A1 as compared with the 2 nd restriction member 5. That is, the end face 32a of the mounting portion 32 in the 1 st direction A1 is located closer to the 1 st direction A1 than the 2 nd restricting member 5. The end face 32a of the mounting portion 32 is a flat face. A2 nd female screw hole 32b to which the 2 nd fastener 202 is screwed is provided in the end face 32a of the mounting portion 32. The 2 nd female screw holes 32b are provided in plural at equal intervals in the circumferential direction. The 2 nd female screw hole 32b is disposed radially outward of the rolling surfaces of the outer ring 23 and the outer ring 24, and does not overlap the outer ring 23 and the outer ring 24 in the axial direction.

As shown in fig. 1, the table 120 is mounted by being abutted against the end face 32a of the mounting portion 32 from the 1 st direction A1. The 2 nd fastener 202 penetrating the table 120 is screwed into the 2 nd female screw hole 32b. Thereby, the table 120 is fixed to the output shaft 3.

As shown in fig. 2, the 1 st restriction member 4 is an annular member. The 1 st restricting member 4 is disposed in the 1 st direction A1 of the inner race 25 and the 1 st main body portion 10. The 1 st restriction member 4 is fastened by the fastener 203. The 1 st restricting member 4 abuts against the end surface 25a of the inner race 25 in the 1 st direction A1. Thus, the bearing portion 2 is restricted from moving in the 1 st direction A1 with respect to the fixed shaft 1.

Further, the 1 st restriction member 4 has the same inner diameter as the outer diameter of the protruding portion 13. That is, the entire inner peripheral surface 4a of the 1 st restriction member 4 is in contact with the outer peripheral surface of the protruding portion 13. Thereby, the 1 st restriction member 4 is prevented from moving in the radial direction to bring the 1 st restriction member 4 into contact with the 2 nd restriction member 5.

As shown in fig. 1, the 2 nd restricting member 5 includes: a fastened portion 50 fastened by a fastener 204; a cover portion 51 extending radially inward from the fastened portion 50; and a cylindrical portion 53 extending from an inner peripheral end of the cover portion 51 in the 2 nd direction A2.

As shown in fig. 2, the fastened portion 50 is disposed in the 1 st direction A1 of the outer ring 23 and the 2 nd main body portion 30. The fastened portion 50 is fastened by the fastener 204. The fastened portion 50 abuts against the end surface 23a of the outer ring 23 in the 1 st direction A1. Thus, the output shaft 3 is restricted from moving in the 1 st direction A1 relative to the bearing portion 2.

The outer diameter of the fastened portion 50 is the same as the inner diameter of the mounting portion 32. That is, the entire periphery of the outer peripheral surface 50a of the fastened portion 50 abuts against the inner peripheral surface of the mounting portion 32. Thereby, the condition that the 2 nd restriction member 5 moves in the radial direction to bring the fastened portion 50 into contact with the 1 st restriction member 4 is avoided.

As shown in fig. 1, the cover portion 51 extends radially inward from the fastened portion 50. The radially inner end of the cover portion 51 is located radially inward of the inner peripheral surface 10b of the 1 st main body portion 10. The cover 51 covers the 1 st restricting member 4 and the protruding portion 13 between the fastened portion 50 and the 1 st restricting member 4 in the 1 st direction A1. Thus, even if the lubricating oil leaks from the bearing portion 2 to the space between the fastened portion 50 and the 1 st restriction member 4, the lubricating oil does not flow out in the 1 st direction A1 beyond the covering portion 51.

The outer peripheral surface 52a of the cylindrical portion 52 faces the inner peripheral surface 1a of the fixed shaft 1. The outer peripheral surface 52a of the cylindrical portion 52 and the inner peripheral surface 1a of the fixed shaft 1 are separated in the radial direction. Thus, an annular space S capable of accommodating a sensor or the like is provided between the cylindrical portion 52 and the fixed shaft 1.

The 1 st cover member 6 is a member that is disposed on the inner peripheral side of the protruding portion 15 and closes the annular space S in the 2 nd direction A2. Specifically, the 1 st cover member 6 is a flat plate-like member having a ring shape centered on the axis AX and a relatively thin thickness in the axial direction. The outer peripheral portion of the 1 st cover member 6 overlaps with the end face 14a of the large diameter portion 14. The outer peripheral portion of the 1 st cover member 6 is fastened by a fastener 205 screwed with the outer peripheral internal screw hole 14 b. Thereby, the 1 st cover member 6 is supported by the fixed shaft 1.

The stator support member 7 is a component disposed on the outer peripheral side of the protruding portion 15. The stator support member 7 includes an annular ring portion 70 and a cylindrical stator mounting portion 71 protruding from an outer peripheral portion of the ring portion 70 in the 1 st direction A1. The inner peripheral portion of the ring portion 70 overlaps with the end face 14a of the large diameter portion 14. The inner peripheral portion of the ring portion 70 is fastened by a fastener 206 screwed with the inner peripheral female screw hole 14 c. Thereby, the stator support member 7 is supported by the fixed shaft 1. The stator mounting portion 71 is provided with a plurality of female screw holes 72 in the circumferential direction at the end face in the 1 st direction A1. The thickness T3 (see fig. 1) from the outer peripheral surface to the inner peripheral surface of the stator mounting portion 71. The thickness of the ring portion 70 in the axial direction is T4 (see fig. 1).

The motor section 8 has a stator 80 and a rotor 81. The rotor 81 includes an annular core fitted into the outer peripheral surface of the 2 nd main body portion 30 of the output shaft 3, and a plurality of permanent magnets (not shown) embedded in the core and arranged at equal intervals in the circumferential direction. The stator 80 includes a cylindrical holder 82, a plurality of cores 83 arranged at equal intervals in the circumferential direction along the inner circumferential surface of the holder 82, bobbins 84 supported by the cores 83, and coils 85 formed by winding a plurality of layers of wires around the bobbins 84.

The holder 82 is disposed in the 1 st direction A1 of the stator mounting portion 71. The holder 82 is provided with a plurality of holes 82a penetrating in the axial direction. The shaft portion of the fastener 207 penetrates the hole 82a of the holder 82 and is screwed into the female screw hole 72 of the stator mounting portion 71 (see a view on the left side of the axis AX in fig. 1). Thereby, the stator 80 is supported by the stator support member 7. The female screw hole 72 of the stator mounting portion 71 and a part of the plurality of hole portions 82a of the holder 82 are used for fastening the fastener 208 of the 2 nd cover member 9 (see a right side view of the axis AX in fig. 1).

The 2 nd cover member 9 is an annular member. The cross-sectional shape of the 2 nd cover member 9 taken radially outward from the axis AX is substantially L-shaped to cover the 1 st direction A1 of the stator 80 and the outer peripheral side of the stator 80. The 2 nd cover member 9 is fastened by a fastener 208 and supported by the stator support member 7. Further, a spacer 90 is interposed between the 2 nd cover member 9 and the holder 82.

Next, the effect of the direct drive motor 100 according to embodiment 1 will be described. In the direct drive motor 100 of embodiment 1, there are no members interposed between the base 110 and the fixed shaft 1, between the fixed shaft 1 and the bearing portion 2, and between the bearing portion 2 and the output shaft 3. That is, the protrusion 15 (the base abutment 12) of the fixed shaft 1 and the base 110 are fastened by the 1 st fastener 201. The projection 15 (base contact portion 12) of the fixed shaft 1 contacts the base 110. Thereby, the fixed shaft 1 is directly supported by the base 110. The inner rings 25 and 26 of the bearing 2 are fitted to the 1 st main body 10 of the fixed shaft 1. Thus, the bearing 2 is directly supported by the fixed shaft 1. The 2 nd main body portion 30 of the output shaft 3 is fitted to the outer rings 23 and 24 of the bearing portion 2. Thus, the output shaft 3 is directly supported by the bearing 2. As described above, the rigidity of supporting the output shaft 3 is high. Thereby, the shake of the output shaft 3 is suppressed when the output shaft 3 rotates. Further, the table 120 is fastened to the output shaft 3 by the 2 nd fastener 202. Thereby, the output shaft 3 directly supports the table 120. As described above, the support table 120 has high rigidity. Thus, the shake of the table 120 is suppressed when the direct drive motor 100 is driven.

Further, the stator 80 has a possibility of vibrating due to magnetic attraction force and magnetic repulsion force generated between it and the rotor 81. If the stator 80 is directly supported by the fixed shaft 1, vibrations of the stator 80 are transmitted to the fixed shaft 1, and a shake may occur in the output shaft 3. However, the stator 80 of embodiment 1 is indirectly supported by the stationary shaft 1 via the stator support member 7. Thereby, the vibration of the stator 80 is absorbed by the stator support member 7, and is hardly transmitted to the fixed shaft 1. As described above, the occurrence of the shake in the output shaft 3 due to the vibration of the stator 80 can be suppressed.

Conventionally, in order to fix other members to the outer peripheral surface of the output shaft 3, a process of cutting the outer peripheral surface of the output shaft 3 by milling or the like to form a cross section into a letter D shape is sometimes performed. When such processing is performed, internal stress is generated in the output shaft 3, and the inner peripheral surface of the output shaft 3 is deformed. If the inner peripheral surface of the output shaft 3 is non-circular, the fitting tightening force of the output shaft 3 becomes uneven in the circumferential direction, which causes rattling. On the other hand, the outer peripheral surface 30a and the inner peripheral surface 30b of the 2 nd main body portion 30 of embodiment 1 are circular when viewed from the axial direction. That is, the outer peripheral surface 30a of the 2 nd main body portion 30 is not subjected to processing such as milling, and the tightening force of the inner peripheral surface 30b of the 2 nd main body portion 30 acts uniformly in the circumferential direction. Thereby, the shake of the output shaft 3 is suppressed when the output shaft 3 rotates.

The outer peripheral surface 10a and the inner peripheral surface 10b of the 1 st main body 10 of embodiment 1 are circular when viewed from the axial direction. Thus, the 1 st main body 10 is not subjected to machining such as milling, and no internal stress acts. The fastening force of the outer peripheral surface 10a of the 1 st main body 10 acts uniformly in the circumferential direction. This suppresses the shake of the bearing 2 with respect to the fixed shaft 1, and further suppresses the shake of the output shaft 3 supported by the bearing 2.

Further, the only member interposed between the fixed shaft 1 and the output shaft 3 is the bearing portion 2. If the number of parts interposed between the fixed shaft 1 and the output shaft 3 increases, the output shaft 3 may be eccentric with respect to the fixed shaft 1 due to the influence of assembly tolerance. That is, according to the direct drive motor 100 of embodiment 1, the influence of the assembly tolerance is small, and the concentricity of the output shaft 3 with respect to the fixed shaft 1 is high. Therefore, the workpiece can be conveyed with high accuracy.

The bearing 2 is in contact with the end face 11a of the 1 st contact portion 11 of the fixed shaft 1, and the bearing 2 is positioned in the axial direction. The end face 31a of the 2 nd contact portion 31 of the output shaft 3 contacts the bearing portion 2, and the output shaft 3 is positioned in the axial direction. Thus, the only part interposed between the fixed shaft 1 and the output shaft 3, which is related to the positioning of the output shaft 3 with respect to the axial direction of the fixed shaft 1, is the bearing part 2. Thus, assembly tolerances are less affected. Therefore, the end face 32a of the attachment portion 32 of the output shaft 3 becomes a desired position (height), and the workpiece can be conveyed with high precision. Further, no other member is interposed between the base 110 and the fixed shaft 1, and no other member is interposed between the output shaft 3 and the table 120. For this reason, the influence of assembly tolerance is small, and the workpiece can be conveyed with high accuracy.

Further, when the fastener is screwed to the female screw hole, the fastener deforms so that the hole diameter of the female screw hole becomes larger. Assuming that the 1 st internally threaded hole 15b overlaps the rolling surfaces of the inner rings 25, 26 in the axial direction, the 1 st internally threaded hole 15b and the inner rings 25, 26 become relatively close. As a result, the 1 st fastener 201 is screwed into the 1 st female screw hole 15b, so that the rolling surfaces of the inner rings 25 and 26 are deformed, and the rolling elements 27 and 28 may not smoothly rotate. However, the 1 st female screw hole 15b of the stationary shaft 1 according to embodiment 1 is disposed radially inward of the rolling surfaces of the inner ring 25 and the inner ring 26, and is separated from the rolling surfaces of the inner ring 25 and the inner ring 26. Thereby, the rolling surfaces of the inner ring 25 and the inner ring 26 are not deformed. Similarly, the 2 nd female screw hole 32b is disposed radially outward of the rolling surfaces of the outer ring 23 and the outer ring 24, and is separated from the rolling surfaces of the inner ring 25 and the inner ring 26. Thereby, the rolling surfaces of the inner ring 25 and the inner ring 26 are not deformed. As described above, the rolling elements 27 and 28 smoothly roll, and the output shaft 3 smoothly rotates.

The thickness T1 in the radial direction of the 1 st main body 10, the thickness T2 in the radial direction of the 2 nd main body 20, the thickness T3 in the axial direction of the ring portion 70, and the thickness T4 in the radial direction of the stator mounting portion 71 are T1 > T2 > T4 > T3 in the order of the thicknesses. The thickness T1 of the 1 st main body 10 in the radial direction is larger than the length (thickness) of the bearing 2 in the radial direction. Therefore, the rigidity of the 1 st main body 10 is improved. This makes it possible to support the output shaft 3 with high rigidity, and to suppress the shake of the output shaft 3. Further, although the 1 st fastener 201 or the like is screw-coupled to the fixed shaft 1 having the 1 st main body portion 10, deformation of the fixed shaft 1 is suppressed. Similarly, the thickness T2 of the 2 nd main body portion 20 in the radial direction is larger than the length (thickness) of the bearing portion 2 in the radial direction. Thus, although the fastener 204 or the like is screwed to the output shaft 3 having the 2 nd main body portion 30, deformation of the output shaft 3 is suppressed. Further, the 2 nd main body portion 30 is larger than both the thickness T3 of the ring portion 70 and the thickness T4 of the stator mounting portion 71. Accordingly, when the direct drive motor 100 is driven, although a magnetic attractive force and a magnetic repulsive force act between the stator 80 and the rotor 81, the 2 nd main body portion 20 is hardly deformed, and the output shaft 3 smoothly rotates. In addition, the disclosure may also be T2. Gtoreq.T4. This can avoid the situation where the ring portion 70 is deflected by the magnetic force acting between the stator 80 and the rotor 81 and the 2 nd main body portion 20 is deformed.

As described above, the direct drive motor 100 according to embodiment 1 includes: a fixed shaft 1 having a cylindrical shape; a bearing part 2, the inner ring 25 and the inner ring 26 of which are embedded on the outer circumferential surface of the fixed shaft 1; an output shaft 3 having a cylindrical shape, the outer ring 23 and the outer ring 24 of the bearing 2 being fitted to the inner peripheral surface of the output shaft 3; a1 st restriction member 4 disposed in A1 st direction A1 in an axial direction parallel to the axis AX of the output shaft 3 with respect to the inner rings 25 and 26; a2 nd restricting member 5 disposed in the 1 st direction A1 with respect to the outer ring 23 and the outer ring 24; and a motor section 8 that applies torque to the output shaft 3. The stationary shaft 1 has: a1 st main body 10 having a tubular shape and fitted with an inner ring 25 and an inner ring 26; a1 st contact portion 11 which is cylindrical, extends from the 1 st main body portion 10 in A2 nd direction A2 opposite to the 1 st direction A1, and contacts an end surface 26a of the inner ring 26 in the 2 nd direction A2; a base contact portion 12 extending from the 1 st contact portion 11 in the 2 nd direction A2, the end surface 15a of the 2 nd direction A2 being in contact with the base 110; and a1 st female screw hole 15b provided in an end surface 15a of the base contact portion 12 in the 2 nd direction A2, and a1 st fastener 201 for fastening the base contact portion 12 and the base 110 is screwed into the 1 st female screw hole 15b. The output shaft 3 has: a2 nd main body portion 30 having a cylindrical shape and fitted to the outer ring 23 and the outer ring 24; a2 nd abutting portion 31 having a cylindrical shape, located closer to the 2 nd direction A2 than the 2 nd main body portion 30, and abutting against the end surface 24a of the outer ring 24 in the 2 nd direction A2; a mounting portion 32 having a tubular shape and extending from the outer peripheral portion of the 2 nd main body portion 30 in the 1 st direction A1, the end face 32a of the 1 st direction A1 protruding in the 1 st direction A1 than the 2 nd restricting member 5; and a2 nd female screw hole 32b provided in an end face 32a of the mounting portion 32 in the 1 st direction A1, and a2 nd fastener 202 for fastening the mounting portion 32 and the object (table 120) is screwed into the 2 nd female screw hole 32b. The 1 st restricting member 4 is fastened to the end face 10c of the 1 st main body portion 10 in the 1 st direction A1, and abuts against the end face 25a of the inner race 25 in the 1 st direction A1. The 2 nd regulating member 5 is fastened to the end surface 30c of the 2 nd main body portion 30 in the 1 st direction A1, and abuts against the end surface 23a of the outer ring 23 in the 1 st direction A1.

According to the direct drive motor 100, the rigidity of supporting the output shaft 3 is high, and the shake of the output shaft 3 can be suppressed. The only part interposed between the fixed shaft 1 and the output shaft 3 is the bearing part 2, and the influence of the assembly tolerance is small. Thereby, concentricity of the output shaft 3 with respect to the fixed shaft 1 is high. The end face 32a of the mounting portion 32 of the output shaft 3 is positioned at a desired position (height). This enables the workpiece to be conveyed with high accuracy.

The motor unit 8 of the direct drive motor 100 according to embodiment 1 includes a rotor 81 fitted to the outer peripheral surface of the output shaft 3, and a stator 80 surrounding the outer peripheral side of the rotor 81. The stator support member 7 extending radially outward from the base contact portion 12 and supporting the stator 80 is fastened to the outer peripheral side of the base contact portion 12.

According to such a direct drive motor 100, the vibration of the stator 80 is hard to be transmitted to the fixed shaft 1. This can suppress the shake of the output shaft 3.

In the direct drive motor 100 according to embodiment 1, the inner shape and the outer shape of the 2 nd main body portion 30 are circular shapes centered on the axis AX.

According to such a direct drive motor 100, the fastening force of the inner peripheral surface 30b of the 2 nd main body portion 30 to the bearing portion 2 acts uniformly in the circumferential direction. This can suppress the shake of the output shaft 3.

In the direct drive motor 100 according to embodiment 1, the inner shape and the outer shape of the 1 st main body 10 are circular shapes centered on the axis AX.

According to such a direct drive motor 100, the fastening force of the outer peripheral surface 10a of the 1 st main body portion 10 to the bearing portion 2 acts uniformly in the circumferential direction. This can suppress the shake of the output shaft 3.

In the direct drive motor 100 according to embodiment 1, the 1 st female screw hole 15b is disposed radially inward of the rolling surfaces of the inner rings 25 and 26. The 2 nd female screw hole 32b is disposed radially outward of the rolling surfaces of the outer ring 23 and the outer ring 24.

According to the direct drive motor 100, deformation of the rolling surfaces of the inner ring 25 and the inner ring 26 and the rolling surfaces of the outer ring 23 and the outer ring 24 is suppressed. Thereby, the rolling elements 27 and 28 smoothly rotate, and the output shaft 3 also smoothly rotates.

The direct drive motor 100 of embodiment 1 has been described above, but the direct drive motor of the present disclosure is not limited to this. For example, the bearing portion 2 includes two bearings, but may be composed of one or three or more bearings.

Description of the reference numerals

100. A direct drive motor; 1. a fixed shaft; 2. a bearing part; 3. an output shaft; 4. a1 st restriction member; 5. a2 nd restriction member; 6. a1 st cover member; 7. a stator support member; 8. a motor section; 9. a2 nd cover member; 10. a1 st main body portion; 11. a1 st contact portion; 12. a base abutment portion; 13. a protruding portion; 14. a large diameter portion; 15. a protruding portion; 15b, 1 st internal thread hole; 30. a2 nd main body portion; 31. a2 nd abutting portion; 32. a mounting part; 32b, a2 nd internal thread hole; 110. a base; 120. a working table.

Claims

1. A direct drive motor, wherein,

the direct drive motor is provided with:

a fixed shaft which is cylindrical;

a bearing part, the inner ring of which is embedded on the outer circumferential surface of the fixed shaft;

an output shaft having a cylindrical shape, wherein an outer ring of the bearing portion is fitted to an inner peripheral surface of the output shaft;

a1 st restriction member disposed in a1 st direction in an axial direction parallel to an axis of the output shaft with respect to the inner ring;

a2 nd restriction member disposed in the 1 st direction with respect to the outer ring; and

a motor section that applies torque to the output shaft,

the fixed shaft has:

a1 st main body part which is cylindrical and is used for embedding the inner ring;

a1 st contact portion which is cylindrical, extends from the 1 st main body portion in a2 nd direction opposite to the 1 st direction, and contacts an end surface of the inner ring in the 2 nd direction;

a base contact portion extending from the 1 st contact portion in the 2 nd direction, the 2 nd end face being in contact with a base; and

a1 st female screw hole provided in the 2 nd end surface of the base abutting portion, a1 st fastener for fastening the base abutting portion and the base being screwed into the 1 st female screw hole,

the output shaft has:

a2 nd main body part which is cylindrical and is used for embedding the outer ring;

a2 nd contact portion having a cylindrical shape, located closer to the 2 nd direction than the 2 nd main body portion, and being in contact with an end surface of the outer ring in the 2 nd direction;

a mounting portion having a tubular shape and extending from an outer peripheral portion of the 2 nd main body portion in the 1 st direction, wherein an end surface in the 1 st direction protrudes in the 1 st direction from the 2 nd restricting member; and

a2 nd internal screw hole provided in the 1 st end surface of the mounting portion, a2 nd fastener for fastening the mounting portion and the object being screwed into the 2 nd internal screw hole,

the 1 st restriction member is fastened to the 1 st end face of the 1 st main body portion and abuts against the 1 st end face of the inner ring,

the 2 nd restricting member is fastened to the 1 st end face of the 2 nd main body portion and abuts against the 1 st end face of the outer ring.

2. The direct drive motor according to claim 1, wherein,

the motor section includes:

a rotor fitted to an outer peripheral surface of the output shaft; and

a stator surrounding an outer peripheral side of the rotor,

and a stator support portion that extends radially outward from the base contact portion and supports the stator is fastened to an outer peripheral side of the base contact portion.

3. The direct drive motor according to claim 1 or 2, wherein,

the inner shape and the outer shape of the output shaft are round shapes taking the axis as the center.

4. A direct drive motor according to any one of claim 1 to 3, wherein,

the inner shape and the outer shape of the fixed shaft are round with the axis as a center.

5. The direct drive motor according to any one of claims 1 to 4, wherein,

the 1 st internal thread hole is arranged at a position on the radial inner side of the rolling surface of the inner ring,

the 2 nd internal thread hole is arranged at a position radially outside the rolling surface of the outer ring.