Encoder, motor unit, and actuator

Abstract

To provide an encoder, a motor unit, and an actuator that can suppress increase of a size.SOLUTION: An encoder 1 is for detecting a rotation of an output shaft 61a of a motor body 61 and includes a first rotary shaft body 10, a first permanent magnet 11, a sensor unit 50, and a first bearing 12. The first rotary shaft body 10 is connected to an end part of an output shaft 61a and rotates in association with rotation of the output shaft 61a. The first permanent magnet 11 is provided in an end part on the -Y side of the first rotary body 10. The sensor of the sensor unit 50 detects a change in the density of the magnetic flux of the first permanent magnet 11 according to the rotation of the first rotary shaft body 10. The first bearing 12 is provided to rotatably support the first rotary shaft body 10 and is made of a magnetic shielding material surrounding the first permanent magnet 11 and shielding magnetism generated from the first permanent magnet 11.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to an encoder, a motor unit, and an actuator. [Background technology]

[0002] Patent Document 1 discloses a mechanical encoder including a case, a driving gear connected to an output shaft of a motor, a permanent magnet, a bearing that rotatably supports the driving gear relative to the case, a member for preventing magnetic interference (magnetic shielding member), and a magnetic sensor that detects changes in the magnetic field of the permanent magnet. The encoder further includes another permanent magnet different from the permanent magnet, and another magnetic sensor that detects changes in the magnetic field of the other permanent magnet. In this encoder, the permanent magnet is provided at an end of the driving gear. The end of the driving gear is provided so as to protrude from the end face of the bearing toward the magnetic sensor so that the magnetic sensor can easily detect the magnetic field generated from the permanent magnet. The magnetic shielding member is provided so as to surround the periphery of the protruding portion of the main rotor, and shields the magnetic field generated from the permanent magnet provided at the end of the driving gear. The magnetic shielding member suppresses the influence of the magnetic field of the permanent magnet of the driving gear on the magnetic sensor that detects changes in the magnetic field of the other permanent magnet, and as a result, the encoder described in Patent Document 1 improves its detection accuracy. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6430800 Summary of the Invention [Problem to be solved by the invention]

[0004] In the encoder described in Patent Document 1, the end of the driving gear is provided so as to protrude from the end face of the bearing toward the magnetic sensor side. Therefore, for example, the length of the driving gear in the protruding direction is increased, and there is a risk that the size of the encoder will be large, and there is room for improvement.

[0005] The present invention has been made in light of the above-mentioned circumstances, and has an object to provide an encoder, a motor unit, and an actuator that can prevent an increase in size. [Means for solving the problem]

[0006] In order to achieve the above object, an encoder according to a first aspect of the present invention comprises: An encoder for detecting rotation of an output shaft of a motor, a first rotating shaft body that is connected to an end of the output shaft and rotates in accordance with the rotation of the output shaft; A first permanent magnet provided at an end of the first rotating shaft body; A case that houses the first rotating shaft body; a first sensor disposed opposite the first permanent magnet and configured to detect a change in magnetic flux density of the first permanent magnet in response to rotation of the first rotating shaft body; a first bearing that rotatably supports the first rotating shaft body relative to the case, surrounds the first permanent magnet, and is made of a magnetic shielding material that shields the magnetic field generated by the first permanent magnet; Equipped with.

[0007] The encoder comprises: a second rotating shaft body that rotates in association with the rotation of the first rotating shaft body; A second permanent magnet provided on the second rotating shaft; a second bearing that rotatably supports the second rotating shaft with respect to the case; a second sensor disposed opposite the second permanent magnet and configured to detect a change in magnetic flux density of the second permanent magnet in response to rotation of the second rotating shaft body; The device may include:

[0008] The second bearing may be formed from a magnetic shielding material that surrounds the second permanent magnet and blocks the magnetic field generated by the second permanent magnet.

[0009] The encoder comprises: a third rotating shaft body that rotates in association with the rotation of the first rotating shaft body; A third permanent magnet provided on the third rotating shaft; a third bearing that rotatably supports the third rotating shaft with respect to the case; a third sensor disposed opposite the third permanent magnet and configured to detect a change in magnetic flux density of the third permanent magnet in response to rotation of the third rotating shaft body; The device may include:

[0010] The third bearing may be formed from a magnetic shielding material that surrounds the third permanent magnet and shields the magnetic field generated from the third permanent magnet.

[0011] The first rotating shaft body is provided with a first gear, The second rotating shaft is provided with a second gear with which the first gear meshes, The second rotating shaft body may rotate in conjunction with rotation of the first rotating shaft body based on meshing between the first gear and the second gear.

[0012] The third rotating shaft body is provided with a third gear with which the first gear of the first rotating shaft body meshes, The third rotating shaft body may rotate in conjunction with rotation of the first rotating shaft body based on meshing between the first gear and the third gear.

[0013] The third rotating shaft body is provided with a third gear with which the second gear of the second rotating shaft body meshes, The third rotating shaft body may rotate in conjunction with rotation of the first rotating shaft body based on meshing between the first gear and the second gear and meshing between the second gear and the third gear.

[0014] The second rotating shaft body has an axial direction parallel to the axial direction of the first rotating shaft body, The second permanent magnet may be provided at an end of the second rotating shaft body on the same side as the end of the first rotating shaft body on which the first permanent magnet is provided.

[0015] The second rotating shaft body has an axial direction parallel to the axial direction of the first rotating shaft body, The second permanent magnet may be provided at an end of the second rotating shaft opposite to an end of the first rotating shaft at which the first permanent magnet is provided.

[0016] An end of the first bearing in the axial direction of the first rotating shaft body may protrude further than an end of the first permanent magnet in the axial direction of the first rotating shaft body.

[0017] An end portion of the first rotating shaft in the axial direction may protrude beyond an end portion of the first permanent magnet in the axial direction of the first rotating shaft.

[0018] A motor unit according to a second aspect of the present invention comprises: A motor having an output shaft; an encoder according to a first aspect that detects rotation of the output shaft of the motor; Equipped with.

[0019] An actuator according to a third aspect of the present invention comprises: A moving body, A motor unit according to a second aspect, which moves the moving body based on rotation of the output shaft; Equipped with. Effect of the Invention

[0020] In the present invention, since the first bearing surrounds the periphery of the first permanent magnet, it is possible to reduce, for example, the axial length of the first rotating shaft body. Therefore, in the present invention, the size of the encoder can be reduced. As a result, in the present invention, it is possible to provide an encoder, a motor unit, and an actuator that can be prevented from becoming large. [Brief description of the drawings]

[0021] [Figure 1] 1 is a perspective view of an actuator according to an embodiment of the present invention; [Diagram 2] 1 is a cross-sectional view of an actuator according to an embodiment of the present invention. [Diagram 3] 1 is an exploded perspective view of an encoder according to an embodiment of the present invention; [Figure 4] 1A is a front view of an encoder according to an embodiment of the present invention, and FIG. [Diagram 5] 1 is an exploded cross-sectional view of an encoder according to an embodiment of the present invention. [Figure 6] FIG. 4 is a cross-sectional view of a first rotating shaft body. [Figure 7] 1A is a cross-sectional view of a second rotating shaft body, and FIG. 1B is a cross-sectional view of a third rotating shaft body. [Figure 8] FIG. 2 is a functional block diagram of an encoder according to an embodiment of the present invention. [Figure 9] Graph (a) is a first graph showing the relationship between the rotation angle and the number of rotations of the first rotating shaft body, the second rotating shaft body, and the third rotating shaft body of the encoder, and graph (b) is a second graph showing the relationship between the rotation angle and the number of rotations of the first rotating shaft body, the second rotating shaft body, and the third rotating shaft body of the encoder. [Figure 10] FIG. 11 is a cross-sectional view of an encoder according to a comparative example. [Figure 11] FIG. 11 is a front view of an encoder according to a first modified example. [Figure 12] FIG. 11 is a cross-sectional view of an encoder according to a second modified example. [Figure 13] FIG. 11 is a cross-sectional view of an encoder according to a third modified example. [Figure 14] FIG. 11 is a cross-sectional view of an encoder according to a fourth modified example. [Figure 15] FIG. 13 is a front view of an encoder according to a fifth modified example. [Figure 16] FIG. 13 is a partially simplified front view of an encoder according to a fifth modified example. [Figure 17] FIG. 13 is a cross-sectional view of an encoder according to a sixth modified example. [Figure 18] FIG. 13 is a cross-sectional view of an encoder according to a seventh modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] The following describes the encoder 1, motor unit 60, and actuator 100 according to the embodiment of the present invention. Note that the Y-axis direction in the figure is parallel to the linear motion direction D1 in which the slide cover C advances and retreats, as shown in Fig. 1, and the X-axis direction and Z-axis direction are perpendicular to the linear motion direction D1. Also, the XY plane in the figure is a horizontal plane parallel to the surface on which the actuator 100 is installed.

[0023] In this embodiment, the actuator 100 is a slider-type actuator in which a slide cover C moves in a linear motion direction D1. As shown in Fig. 2, the actuator 100 includes, in addition to the motor unit 60 and slide cover C, a ball screw 70, an actuator housing 80, and a moving body 90.

[0024] The motor unit 60 has a motor body 61 (motor), a motor casing 62, a first coupling 63, and a mechanical encoder 1 that detects the rotation of an output shaft 61a of the motor unit 60 (more specifically, the rotation angle and number of rotations of the output shaft 61a, etc.). The motor unit 60 is configured as a single unit that is detachable from the actuator housing 80, for example. However, this is not limited to this. The motor unit 60 may be fixed integrally to the actuator housing 80 so that it cannot be detached.

[0025] The motor body 61 is, for example, a stepping motor or a servo motor, and has an output shaft 61a (rotating shaft), a rotor, a stator, etc. The motor body 61 is supplied with power from a commercial power source or a DC power source via an actuator cable. When power is supplied to the motor body 61, the rotor of the motor body 61 rotates. The rotational motion of the rotor is output to the output shaft 61a. The output shaft 61a is connected to a ball screw shaft 71 of a ball screw 70 via a pair of a first coupling 63 and a second coupling 73. The output shaft 61a rotates based on the rotational motion of the rotor of the motor body 61, and as a result, the ball screw shaft 71 of the ball screw 70 rotates together with the output shaft 61a.

[0026] The motor casing 62 houses the motor body 61 and protects the motor body 61 .

[0027] The first coupling 63 is fixed to the output shaft 61a of the motor body 61. The first coupling 63 transmits the rotational motion of the output shaft 61a of the motor body 61 to the ball screw shaft 71 of the ball screw 70 by engaging with a second coupling 73 fixed to the ball screw shaft 71 of the ball screw 70.

[0028] As shown in Fig. 3 and Fig. 4, the encoder 1 includes a first rotating shaft body 10, a first permanent magnet 11, a first bearing 12, a second rotating shaft body 20, a second permanent magnet 21, second bearings 22-1 and 22-2, a third rotating shaft body 30, a third permanent magnet 31, third bearings 32-1 and 32-2, a case 40, and a sensor unit 50. In the encoder 1, the three rotating shaft bodies, the first rotating shaft body 10, the second rotating shaft body 20, and the third rotating shaft body 30, are used to detect the rotation angle and the number of rotations of the output shaft 61a of the motor main body 61. As a result, a controller 200 (described later) of the actuator 100 can calculate the absolute position of the moving body 90.

[0029] As shown in Figs. 4 and 5, the first rotating shaft body 10 is formed in a substantially cylindrical shape with the Y-axis direction as the column axis direction, and is a member that is provided so as to be rotatable around the Y-axis direction. The first rotating shaft body 10 is formed of, for example, a soft magnetic material. A first gear 10a is formed on the outer circumferential surface of the first rotating shaft body 10. More specifically, as shown in Fig. 6, the first rotating shaft body 10 has a cylindrical member 10-1 and a cylindrical member 10-2 in which a through hole 10b is formed. The first gear 10a is formed on the outer circumferential surface of the cylindrical member 10-2. The cylindrical member 10-1 and the output shaft 61a are fitted into the through hole 10b of the cylindrical member 10-2 from both sides. As a result, the cylindrical member 10-2 is connected to the end of the output shaft 61a of the motor main body 61, and the first rotating shaft body 10 rotates with the rotation of the output shaft 61a. Therefore, the first rotating shaft body 10 is configured as a main drive shaft that is directly connected to the output shaft 61 a of the motor body 61 .

[0030] The first permanent magnet 11 is a permanent magnet provided at the end of the first rotating shaft body 10 on the -Y side. In the present embodiment, the first permanent magnet 11 is provided so that a portion of it is exposed from the end of the first rotating shaft body 10. However, this is not limited to this. The method of attaching or fixing the first permanent magnet 11 to the end of the first rotating shaft body 10 is arbitrary. For example, the first permanent magnet 11 may be fixed to the end face of the end of the first rotating shaft body 10 on the -Y side with an adhesive or the like.

[0031] The first bearing 12 is provided to rotatably support the first rotating shaft body 10 with respect to the case 40. In this embodiment, the first bearing 12 supports the first rotating shaft body 10 at the end of the first rotating shaft body 10 on the -Y side. The first bearing 12 is formed of a magnetic shielding material that shields the magnetic field generated from the first permanent magnet 11 so as to suppress the magnetic field generated from the first permanent magnet 11 from affecting the sensors S2 and S3. The magnetic shielding material of the first bearing 12 is, for example, a soft magnetic material. However, the magnetic shielding material of the first bearing 12 is not limited to this, and may be a material other than a soft magnetic material as long as it is a material that can shield magnetic fields. In addition, the first bearing 12 is provided surrounding the periphery of the first permanent magnet provided at the end of the first rotating shaft body 10 on the -Y side. As a result, the first rotating shaft body 10 is provided so that its end on the -Y side does not protrude from the end face 12a on the -Y side of the first bearing 12. Moreover, the first bearing 12 is formed so that its length L1 in the Y-axis direction is greater than the length L2 in the Y-axis direction of the first permanent magnet 11 (L1>L2). This makes it easier for the first bearing 12 to surround the periphery of the first permanent magnet 11.

[0032] As shown in Figs. 4 and 5, the second rotating shaft body 20 is formed in a substantially cylindrical shape with the Y-axis direction as the column axis direction, and is a member provided so as to be rotatable around the Y-axis direction. The second rotating shaft body 20 is formed of, for example, a soft magnetic material. The second rotating shaft body 20 is provided so that its axial direction is parallel to the axial direction of the first rotating shaft body 10. In addition, a second gear 20a that meshes with the first gear 10a of the first rotating shaft body 10 is formed on the outer circumferential surface of the second rotating shaft body 20. The second rotating shaft body 20 is provided so as to rotate with the rotation of the first rotating shaft body 10 based on the meshing between the first gear 10a and the second gear 20a. In detail, the second rotating shaft body 20 has a cylindrical member 20-1 and a cylindrical member 20-2 in which a through hole 20b is formed, as shown in Fig. 7(A). The second gear 20a is formed on the outer circumferential surface of the cylindrical member 20-2. The columnar member 20-1 is fitted into the through hole 20b of the cylindrical member 20-2. The second rotating shaft body 20 is configured as a driven shaft that is indirectly connected to the output shaft 61a of the motor body 61 via the first rotating shaft body .

[0033] The second permanent magnet 21 is a permanent magnet provided at the end of the second rotating shaft body 20 on the -Y side. In the present embodiment, the second permanent magnet 21 is provided so that a portion of it is exposed from the end of the second rotating shaft body 20. However, this is not limited to this. The method of attaching or fixing the second permanent magnet 21 to the end of the second rotating shaft body 20 is arbitrary. For example, the second permanent magnet 21 may be fixed to the end face of the end of the second rotating shaft body 20 on the -Y side with an adhesive or the like.

[0034] The second bearings 22-1 and 22-2 are provided to rotatably support the second rotating shaft body 20 with respect to the case 40. In this embodiment, two second bearings 22-1 and 22-2 are provided, and support the second rotating shaft body 20 at both the -Y side end and the +Y side end of the second rotating shaft body 20. The second bearings 22-1 and 22-2 are formed of a magnetic shielding material that shields the magnetic field generated from the second permanent magnet 21 so as to suppress the magnetic field generated from the second permanent magnet 21 from affecting the sensors S1 and S3. The magnetic shielding material of the second bearings 22-1 and 22-2 is, for example, a soft magnetic material. However, the magnetic shielding material of the second bearings 22-1 and 22-2 is not limited to this, and may be a material other than a soft magnetic material as long as it can shield magnetic fields. In addition, the second bearing 22-1, which is one of the second bearings 22-1 and 22-2, is provided to surround the periphery of the second permanent magnet 21 provided at the end of the second rotating shaft body 20 on the -Y side. As a result, the second rotating shaft body 20 is provided so that its -Y side end does not protrude from the -Y side end face 22a of the second bearing 22. In addition, the second bearing 22 provided at the end on the -Y side is formed so that its length L3 in the Y axis direction is greater than the length L4 of the second permanent magnet 21 in the Y axis direction (L3>L4). As a result, the second bearing 22 easily surrounds the periphery of the second permanent magnet 21.

[0035] As shown in Figs. 4 and 5, the third rotating shaft body 30 is formed in a substantially cylindrical shape with the Y-axis direction as the column axis direction, and is a member provided so as to be rotatable around the Y-axis direction, and is formed in roughly the same shape as the second rotating shaft body 20. The third rotating shaft body 30 is formed, for example, of a soft magnetic material. The third rotating shaft body 30 is provided so that its axial direction is parallel to the axial direction of the first rotating shaft body 10 and the second rotating shaft body 20. In addition, a third gear 30a that meshes with the first gear 10a of the first rotating shaft body 10 is formed on the outer circumferential surface of the third rotating shaft body 30. The third rotating shaft body 30 is provided so as to rotate with the rotation of the first rotating shaft body 10 based on the meshing between the first gear 10a and the third gear 30a. In more detail, the third rotating shaft body 30 has a columnar member 30-1 and a cylindrical member 30-2 in which a through hole 30b is formed, as shown in Fig. 7(B). The third gear 30a is formed on the outer circumferential surface of the cylindrical member 30-2. The columnar member 30-1 is fitted into the through hole 30b of the cylindrical member 30-2. The third rotating shaft body 30, like the second rotating shaft body 20, is configured as a driven shaft indirectly connected to the output shaft 61a of the motor main body 61 via the first rotating shaft body 10.

[0036] The third permanent magnet 31 is a permanent magnet provided at the end of the third rotating shaft body 30 on the -Y side. In this embodiment, the third permanent magnet 31 is provided so that a part of it is exposed from the end of the third rotating shaft body 30. However, this is not limited to this. The third permanent magnet 31 may be attached or fixed to the end of the third rotating shaft body 30 by any method. For example, the third permanent magnet 31 may be fixed to the end face of the end of the third rotating shaft body 30 on the -Y side with an adhesive or the like.

[0037] The third bearings 32-1 and 32-2 are provided to rotatably support the third rotating shaft body 30 with respect to the case 40. In this embodiment, two third bearings 32-1 and 32-2 are provided, and support the third rotating shaft body 30 at both the end on the -Y side and the end on the +Y side of the third rotating shaft body 30. The third bearings 32-1 and 32-2 are formed of a magnetic shielding material that shields the magnetism generated from the third permanent magnet 31 so as to suppress the third permanent magnet 31 from affecting the sensors S1 and S2. The magnetic shielding material of the third bearings 32-1 and 32-2 is, for example, a soft magnetic material. However, the magnetic shielding material of the third bearings 32-1 and 32-2 is not limited to this, and may be a material other than a soft magnetic material as long as it is a material that can shield magnetism. Moreover, the third bearing 32-1, which is one of the third bearings 32-1 and 32-2, is provided so as to surround the periphery of the third permanent magnet provided at the end of the third rotating shaft body 30 on the -Y side. As a result, the third rotating shaft body 30 is provided so that its -Y side end does not protrude from the -Y side end face 32a of the third bearing 32. Moreover, the third bearing 32 provided at the end on the -Y side is formed so that its length L5 in the Y axis direction is greater than the length L6 in the Y axis direction of the third permanent magnet 31 (L5>L6). As a result, the third bearing 32 easily surrounds the periphery of the third permanent magnet 31.

[0038] 4 and 5, in this embodiment, the -Y end face of the first rotating shaft body 10, the -Y end face 12a of the first bearing 12, the -Y end face of the second rotating shaft body 20, the -Y end face 22a of the second bearing 22, the -Y end face of the third rotating shaft body 30, and the -Y end face 32a of the third bearing 32 are located on the same plane P perpendicular to the Y axis direction. Also, as shown in FIG. 4(A), the first rotating shaft body 10, the second rotating shaft body 20, and the third rotating shaft body 30 are arranged in a row along a straight line L7 that passes through the center axis A of the first rotating shaft body 10 and is perpendicular to the Y axis direction.

[0039] 3 and 5, the case 40 houses and protects each component of the encoder 1. In the present embodiment, the case 40 has a first case portion 41, a second case portion 42, and a third case portion 43, which are stacked in order in the Y-axis direction.

[0040] The first case part 41 is a plate-like member configured as a part on the rear end side (+Y side) of the case 40. The first case part 41 is fixed to the motor casing 62 of the motor unit 60 by a fastener 44. A through hole 41a that penetrates the first case part 41 in the Y-axis direction is formed. The first rotating shaft body 10 is inserted and disposed in the through hole 41a.

[0041] The second case part 42 is a plate-like member disposed between the first case part 41 and the third case part 43. The second case part 42 is fixed to the third case part 43 by a fastener 45. The second case part 42 has three through holes 42a, 42b, 42c penetrating in the Y-axis direction. The first rotating shaft body 10, the second rotating shaft body 20, and the third rotating shaft body 30 are inserted and disposed in the three through holes 42a, 42b, 42c, respectively.

[0042] The third case part 43 is a lid-like member configured as a part of the tip side (-Y side) of the case 40. The third case part 43 has three through holes 43a, 43b, 43c penetrating in the Y-axis direction. The first rotating shaft body 10, the second rotating shaft body 20, and the third rotating shaft body 30 are inserted and arranged in the three through holes 43a, 43b, 43c, respectively. Note that, for example, as shown in FIG. 4(B), the end face on the -Y side of the third case part 43 is located on the same plane P as the end faces on the -Y side of the first rotating shaft body 10, the second rotating shaft body 20, and the third rotating shaft body 30. As a result, the end faces on the -Y side of the first rotating shaft body 10, the second rotating shaft body 20, and the third rotating shaft body 30 are exposed from the end face on the -Y side of the third case part 43. Note that the -Y side end face of the third case portion 43 is located on the same plane P as the -Y side end faces of the first rotating shaft body 10, the second rotating shaft body 20, and the third rotating shaft body 30, but this is just an example and is not limited to this. The -Y side end face of the third case portion 43 does not have to be located on the same plane P, and may protrude from the same plane P.

[0043] The sensor unit 50 has a substrate 51, sensors S1, S2, S3, a CPU (Central Processing Unit) 52a, and a communication element (circuit) 52b. As shown in FIG. 8, the sensors S1, S2, S3, the CPU 52a, and the communication element 52b are mounted on the substrate 51. In addition, a controller 200, which is an external device, is connected to the substrate 51. As shown in FIG. 4 and FIG. 5, the sensor unit 50 detects the rotation angle of the output shaft 61a of the motor unit 60 from the change in the magnetic field (magnetic field) of the first permanent magnet 11, the second permanent magnet 21, and the third permanent magnet 31 according to the rotation of the first rotating shaft body 10, the second rotating shaft body 20, and the third rotating shaft body 30 (more specifically, the change in magnetic flux density), and calculates the rotation speed of the output shaft 61a, and is used to transmit signals corresponding to the rotation angle and the rotation speed to a controller 200 for controlling the actuator 100 (motor body 61).

[0044] The substrate 51 is provided so that the mounting surface on which the sensors S1, S2, and S3 are mounted faces the end face on the -Y side of the third case portion 43. As a result, the sensors S1, S2, and S3 are arranged to face the first permanent magnet 11, the second permanent magnet 21, and the third permanent magnet 31. The sensors S1, S2, and S3 are arranged on the respective axes (on a line along the Y axis) of the first, second, and third rotating shaft bodies 10, 20, and 30 together with the first, second, and third permanent magnets 11, 21, and 31. The sensors S1, S2, and S3 are also arranged on the respective axes of the first, second, and third rotating shaft bodies 10, 20, and 30 at a predetermined distance (gap) from the end faces on the -Y side of the first, second, and third permanent magnets 11, 21, and 31. Here, the predetermined distance (gap) means a distance sufficient for each of the sensors S1, S2, and S3 to detect a change in the magnetic flux density of the corresponding first, second, and third permanent magnets 11, 21, and 31.

[0045] As shown in FIG. 3 and FIG. 4, the substrate 51 is supported on the third case part 43 of the case 40 by a support member 53 that can adjust the gap between the sensors S1, S2, S3 and the first permanent magnet 11, the second permanent magnet 21, and the third permanent magnet 31. In this embodiment, the support member 53 is a bolt that is screwed into a screw hole 43d formed in the third case part 43. Furthermore, the support member 53 is also screwed into a screw hole 42d formed in the second case part 42 and a screw hole 41b formed in the first case part 41. By screwing the support member 53 into the screw holes 43d, 42d, and 41b, the substrate 51, the first case part 41, the second case part 42, and the third case part 43, including the sensor unit 50, are integrated. In addition, a connector 54 is mounted on the surface of the substrate 51 on the -Y side opposite to the surface on which the sensors S1, S2, and S3 are mounted. A controller 200 (see FIG. 8) is connected to this connector 54 via a cable.

[0046] As shown in FIG. 4 and FIG. 5, the sensors S1, S2, and S3 are magnetic sensors that detect changes in the magnetic flux density of the first permanent magnet 11, the second permanent magnet 21, and the third permanent magnet 31. The sensors S1 to S3 are configured to include, for example, a Hall element, detect changes in the magnetic flux density from the first permanent magnet 11, the second permanent magnet 21, and the third permanent magnet 31, and output a voltage signal according to the detected change in the magnetic flux density. The voltage signal is output to the CPU 52a of the sensor unit 50 as shown in FIG. 8. This voltage signal is a signal corresponding to the rotation angle (absolute angle) of the first, second, and third rotating shaft bodies 10, 20, and 30. In the first embodiment, the sensors S1, S2, and S3 are Hall sensors that include a Hall element. However, this is not limited to this. The sensors S1, S2, and S3 may be MR (Magneto Resistive) sensors that include a magnetoresistance effect element.

[0047] As shown in Figs. 4 and 8, the CPU 52a processes the voltage signals input from the sensors S1, S2, and S3 to calculate the rotation angles (absolute angles) of the first, second, and third rotating shaft bodies 10, 20, and 30. Since the rotation angle of the first rotating shaft body 10 is the same as the rotation angle of the output shaft 61a of the motor main body 61, the CPU 52a can also calculate the rotation angle (absolute angle) of the output shaft 61a by calculating the rotation angle of the first rotating shaft body 10. The CPU 52a also calculates the rotation speed of the output shaft 61a based on the rotation angles of the first, second, and third rotating shaft bodies 10, 20, and 30. The CPU 52a outputs signals corresponding to the calculated rotation angles of the first, second, and third rotating shaft bodies 10, 20, and 30 and the rotation speed of the output shaft 61a to the controller 200.

[0048] The communication element 52b is a circuit component that performs communication between the CPU 52a and the controller 200 of the actuator 100 that is installed externally.

[0049] The controller 200 includes, for example, a controller CPU (Central Processing Unit), a storage unit, a display unit, an input unit, and an interface unit. As shown in Figs. 2 and 8, the controller 200 calculates the absolute position of the moving body 90 based on a signal from the CPU 52a. The controller 200 also controls the operation of the actuator 100 (motor body 61). The details of the operation of the actuator 100 are set by a teaching pendant or the like connected to the controller 200, and are stored in the storage unit of the controller 200. The controller CPU of the controller 200 reads out programs and data from the storage unit and executes programs for the operation of the actuator 100 (motor body 61).

[0050] In addition to the motor unit 60 configured as described above, the actuator 100 further includes a ball screw 70, an actuator housing 80, and a moving body 90, as shown in FIGS.

[0051] The ball screw 70 has a ball screw shaft 71 and a ball screw nut 72 that is screwed onto the ball screw shaft 71 .

[0052] The ball screw shaft 71 causes the ball screw nut 72 to move linearly based on the screw engagement with the ball screw nut 72. The ball screw shaft 71 has a ball screw shaft main body 71a whose outer circumferential surface is configured as a helical ball screw surface, and ends 71b, 71c formed with a smaller diameter than the ball screw shaft main body 71a. A second coupling 73 is fixed to the end 71c on the -Y side of the ends 71b, 71c. This second coupling 73 engages with the first coupling 63 fixed to the output shaft 61a of the motor unit 60.

[0053] The ball screw nut 72 is disposed on the outer periphery of a ball screw shaft main body 71a of the ball screw shaft 71. The ball screw nut 72 is fitted onto the ball screw shaft 71 via a plurality of ball screw rolling elements. As the ball screw rolling elements roll, the rotational motion of the ball screw shaft 71 is smoothly converted into linear motion of the ball screw nut 72. In addition, the ball screw nut 72 is fixed to the moving body 90 by fasteners such as bolts or screws.

[0054] The actuator housing 80 accommodates and protects the ball screw 70 and the moving body 90. The actuator housing 80 has, for example, a base 81, a pair of side covers 82R, 82L, a seat member 83, a front bracket 84, and a rear bracket 85.

[0055] A rail is provided on the base 81. A moving body 90 is supported on the rail of the base 81 via a linear guide rolling element. The linear guide rolling element rolls on this rail, causing the moving body 90 to smoothly reciprocate relative to the base 81 in a linear motion direction D1.

[0056] The side covers 82R, 82L form side wall portions on both sides of the actuator housing 80. The side covers 82R, 82L, together with the base 81, protect the various components inside the actuator 100.

[0057] The sheet member 83 is a generally rectangular stainless steel sheet whose longitudinal direction is in the Y-axis direction, and closes the opening 82a between the side covers 82R and 82L. An end of the sheet member 83 on the +Y side is fixed to a front bracket 84. An end of the sheet member 83 on the -Y side is fixed to a rear bracket 85.

[0058] The front bracket 84 is fixed to the end side on the +Y side of the base 81. The front bracket 84 has, for example, a bearing 84a, and supports the end 71b of the ball screw shaft 71 rotatably by means of this bearing 84a.

[0059] The rear bracket 85 is fixed to the end portion on the -Y side of the base 81. The rear bracket 85 has, for example, a bearing 85a, and supports the end portion 71c of the ball screw shaft 71 rotatably by means of this bearing 85a.

[0060] The moving body 90 is a member that slides together with the ball screw nut 82 in both the +Y and -Y directions. A through hole 91 that penetrates in the Y-axis direction is formed in the moving body 90. The ball screw shaft 71 is inserted into this through hole 91, and the ball screw nut 72 is inserted and fixed in place. A slide cover C is attached to the moving body 90 from the upper side (+Z side). The sheet member 83 penetrates the slide cover C in the Y-axis direction. This allows the slide cover C to move in the linear motion direction D1 along the sheet member 83.

[0061] Next, calculation of the rotation speed of the first rotating shaft body 10 based on the rotation angle of the first rotating shaft body 10 as the main shaft, and the rotation angle of the second rotating shaft body 20 and the third rotating shaft body 30 as the driven shaft, and calculation of the absolute position of the moving body 90 will be explained using Figures 2, 4, 8 and 9.

[0062] First, the sensors S1, S2, and S3 of the sensor unit 50 detect changes in the magnetic flux density of the first permanent magnet 11, the second permanent magnet 21, and the third permanent magnet 31 in response to the rotation of the first rotating shaft body 10, the second rotating shaft body 20, and the third rotating shaft body 30, as shown in Fig. 4 and Fig. 5. Then, the sensors S1, S2, and S3 output voltage signals corresponding to the rotation angles (absolute angles) of the first, second, and third rotating shaft bodies 10, 20, and 30 to the CPU 52a, as shown in Fig. 8.

[0063] Next, based on the voltage signals input from the sensors S1, S2, S3, the CPU 52a calculates the rotation angles (absolute angles) of the first, second, and third rotating shaft bodies 10, 20, and 30, and the rotation angle (absolute angle) of the output shaft 61a of the motor unit 60. Furthermore, based on these rotation angles (absolute angles), the CPU 52a calculates the rotation speed of the first rotating shaft body 10 (output shaft 61a) as follows.

[0064] The rotation speed of the first rotating shaft body 10 (output shaft 61a) is calculated using the rotation angle of the second rotating shaft body 20 and the rotation angle of the third rotating shaft body 30. The number of teeth N1 of the first gear 10a of the first rotating shaft body 10, the number of teeth N2 of the second gear 20a of the second rotating shaft body 20, and the number of teeth N3 of the third gear 30a of the third rotating shaft body 30 are different from each other and are set to be mutually prime. In this embodiment, the number of teeth N1 of the first gear 10a is set to "25", the number of teeth N2 of the second gear 20a is set to "24", and the number of teeth N3 of the third gear 30a is set to "23". However, the number of teeth N1, N2, and N3 are not limited to this. The number of teeth N1, N2, and N3 may be numbers of teeth other than "25", "24", and "23".

[0065] 2 and 4, the maximum value of the absolute position of the moving body 90 that can be calculated is determined by the number of combinations of the rotation angles of the second rotating shaft body 20 and the third rotating shaft body 30 relative to the rotation angle of the first rotating shaft body 10, and the greater the number of combinations, the greater the absolute position of the moving body 90 that can be calculated. In other words, since the maximum value of the absolute position of the moving body 90 to be calculated is determined by the movable distance of the moving body 90 in the linear motion direction D1, the number of teeth N1 of the first gear 10a, the number of teeth N2 of the second gear 20a, and the number of teeth N3 of the third gear 30a are set according to the movable distance of the moving body 90 in the linear motion direction D1.

[0066] As the first rotating shaft body 10 is rotated, the rotation angles of the second rotating shaft body 20 and the third rotating shaft body 30 deviate from the rotation angle of the first rotating shaft body 10, as shown in the graph of Fig. 9. In Figs. 9(a) and 9(b), the horizontal axis indicates the rotation speed of the first rotating shaft body 10, the second rotating shaft body 20, and the third rotating shaft body 30, and the vertical axis indicates the rotation angles of the first rotating shaft body 10, the second rotating shaft body 20, and the third rotating shaft body 30.

[0067] As shown in Fig. 9(a), before the first rotating shaft body 10 starts to rotate, the rotation angles of the first rotating shaft body 10, the second rotating shaft body 20, and the third rotating shaft body 30 are the same. At the start of this rotation, the moving body 90 is disposed at the most proximal end side (-Y side, left side in Fig. 2). The position of the moving body 90 before the start of rotation is set as the origin, that is, the absolute position of the moving body 90, and therefore the position where the number of rotations of the ball screw shaft 71 is "0". It is assumed that the first rotating shaft body 10 is rotated forward from the state before the start of rotation of the first rotating shaft body 10 to move the moving body 90 forward in the +Y direction. As the first rotating shaft body 10 rotates, the second rotating shaft body 20 and the third rotating shaft body 30 also rotate accordingly, and a deviation occurs in the rotation angle of the second rotating shaft body 20 relative to the rotation angle of the first rotating shaft body 10. At this time, a deviation also occurs in the rotation angle of the third rotating shaft body 30 relative to both the rotation angles of the first rotating shaft body 10 and the second rotating shaft body 20. These deviations gradually increase as the first rotating shaft body 10 rotates.

[0068] As the first rotating shaft body 10 continues to rotate, at a certain point in time the deviation between the rotation angle of the first rotating shaft body 10 and the rotation angle of the second rotating shaft body 20 or the third rotating shaft body 30 reaches a maximum. After that, as shown in Fig. 9(b), the deviation between the rotation angle of the first rotating shaft body 10 and the rotation angle of the second rotating shaft body 20 or the third rotating shaft body 30 gradually decreases, and eventually the rotation angles of the first rotating shaft body 10, the second rotating shaft body 20, and the third rotating shaft body 30 match again, returning to the state they were in before the first rotating shaft body 10 started to rotate.

[0069] In this manner, while the rotation angles of the first rotating shaft body 10, the second rotating shaft body 20, and the third rotating shaft body 30 change, there is no consistency in the combination of the rotation angles of the first rotating shaft body 10, the second rotating shaft body 20, and the third rotating shaft body 30. From the combination of the rotation angles of the second rotating shaft body 20 and the third rotating shaft body 30, the rotation speed of the first rotating shaft body 10, and therefore the rotation speed of the ball screw shaft 71, can be calculated. Moreover, the number (n) of combinations of the rotation angles of the second rotating shaft body 20 and the third rotating shaft body 30 is calculated by the following formula (1). n = N2 × N3 = 24 × 23 = 552 (1) however, n: the number of combinations of the rotation angles of the second rotating shaft body 20 and the third rotating shaft body 30 corresponding to the rotation speed of the first rotating shaft body 10 N2: number of teeth of the second gear 20a of the second rotating shaft 20 N3: number of teeth of the third gear 30a of the third rotating shaft 30

[0070] The CPU 52a calculates the rotation speed of the first rotating shaft body 10 from the combination of the rotation angle of the second rotating shaft body 20 and the rotation angle of the third rotating shaft body 30 described above. As described above, the CPU 52a calculates the rotation speed of the first rotating shaft body 10 (output shaft 61a) in addition to the rotation angles (absolute angles) of the first, second, and third rotating shaft bodies 10, 20, and 30 and the output shaft 61a. Furthermore, since the rotation angle and rotation speed of the output shaft 61a and the ball screw shaft 71 are the same as the rotation angle and rotation speed of the first rotating shaft body 10, as a result, the CPU 52a also calculates the rotation angle and rotation speed of the output shaft 61a and the ball screw shaft 71. As described above, the calculation of the rotation angle and rotation speed of the output shaft 61a and the ball screw shaft 71 is completed by the CPU 52a.

[0071] Next, as shown in FIG. 8, the CPU 52a outputs a signal corresponding to the calculated rotation angle and number of rotations of the output shaft 61a to the controller 200 via the communication element 52b.

[0072] 2 and 8, signals corresponding to the rotation angle and rotation speed of the output shaft 61a are input from the CPU 52a to the controller 200. The controller 200 calculates the absolute position of the moving body 90 from the rotation angle and rotation speed of the output shaft 61a and the pitch of the spiral groove of the ball screw shaft 71. With the above, the calculation of the absolute position of the moving body 90 is completed by the controller 200.

[0073] As described above, in the encoder 1 according to this embodiment, as shown in Fig. 4, the first bearing 12 surrounds the first permanent magnet 11 and is made of a magnetic shielding material that shields the magnetic field generated by the first permanent magnet 11. This makes it possible to reduce the length of the first rotating shaft body 10 in the Y-axis direction and the column axis direction. This allows the size of the encoder to be reduced in the present invention.

[0074] For example, in the encoder 1A according to the comparative example, as shown in Fig. 10, the first bearing 12 is provided without surrounding the periphery of the first permanent magnet 11. In this case, the first rotating shaft body 10 is provided with its -Y side end protruding from the -Y side end face 12a of the first bearing 12. This may increase the length of the first rotating shaft body 10 in the Y axis direction and the column axis direction, which may increase the size of the encoder 1A. This may result in an increase in the size of the motor unit including the encoder 1A and the actuator including the motor unit.

[0075] In contrast to this, in the encoder 1 according to this embodiment, as shown in Fig. 4, the first bearing 12 is formed to surround the periphery of the first permanent magnet 11. This makes it possible to provide the first rotating shaft body 10 such that its -Y side end does not protrude from the -Y side end face 12a of the first bearing 12. This makes it possible to reduce the length of the first rotating shaft body 10 in the Y-axis direction, that is, to achieve a low height. As a result, this embodiment can provide an encoder 1 etc. that can prevent an increase in size.

[0076] 10, in the encoder 1A according to the comparative example, the end portion on the -Y side of the first rotating shaft body 10 protrudes from the end face 12a on the -Y side of the first bearing 12. For this reason, in the encoder 1A, in order to suppress the magnetism of the first permanent magnet 11 from affecting the sensors S2 and S3 that detect changes in the magnetic flux density of the other second permanent magnet 21 and third permanent magnet 31, it becomes necessary to separately provide a magnetic shielding member 110 that surrounds the periphery of the first permanent magnet 11 provided in the protruding portion of the first bearing 12 to shield the magnetism generated from the first permanent magnet 11.

[0077] In contrast, in this embodiment, as shown in Fig. 4, the first bearing 12 has the original function of supporting the first rotating shaft 10 rotatably relative to the case 40, and also has the function of shielding the magnetism of the first permanent magnet 11 so as to suppress the influence of the magnetism generated from the first permanent magnet 11 on the sensors S2 and S3 other than the sensor S1 that detects the change in the magnetic flux density of the first permanent magnet 11. As a result, in the encoder 1 according to this embodiment, it is not necessary to prepare a magnetic shielding member in addition to the first bearing 12, and the number of parts can be reduced compared to the encoder 1A according to the comparative example. As a result, in the encoder 1 according to this embodiment, the number of parts can be reduced and the low profile of the encoder 1 can be achieved.

[0078] Moreover, in the encoder 1 according to this embodiment, the second bearing 22 surrounds the second permanent magnet 21 and is made of a magnetic shielding material that shields the magnetic field generated from the second permanent magnet 21. Therefore, the lengths of the second rotating shaft body 20 in the Y-axis direction and the column axis direction can also be reduced. Similarly, the third bearing 32 surrounds the third permanent magnet 31 and is made of a magnetic shielding material that shields the magnetic field generated from the third permanent magnet 31. Therefore, the lengths of the third rotating shaft body 30 in the Y-axis direction and the column axis direction can also be reduced. As a result, in this embodiment, the size of the encoder 1 can be further reduced.

[0079] In addition, in this embodiment, the second bearing 22 has the original function of supporting the second rotating shaft body 20 rotatably relative to the case 40, and also has the function of shielding the magnetism of the second permanent magnet 21 so as to suppress the magnetism generated from the second permanent magnet 21 from affecting the sensors S1 and S3 other than the sensor S2 that detects the change in the magnetic flux density of the second permanent magnet 21. Similarly, the third bearing 32 has the original function of supporting the third rotating shaft body 30 rotatably relative to the case 40, and also has the function of shielding the magnetism of the third permanent magnet 31 so as to suppress the magnetism generated from the third permanent magnet 31 from affecting the sensors S1 and S2 other than the sensor S3 that detects the change in the magnetic flux density of the third permanent magnet 31. Therefore, in the encoder 1 according to this embodiment, there is no need to prepare a magnetic shielding member in addition to the second bearing 22 and the third bearing 32, and the number of parts can be further reduced.

[0080] Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment.

[0081] For example, in this embodiment, as shown in FIG. 4(A), the third gear 30a of the third rotating shaft body 30 configured as a driven shaft meshes with the first gear 10a of the first rotating shaft body 10 configured as a driving shaft. However, this is not limited to this. As in the encoder 2 according to the modified example 1 shown in FIG. 11, the third gear 30a of the third rotating shaft body 30 may mesh with the second gear 20a of the second rotating shaft body 20 configured as the same driven shaft. In this case, the third rotating shaft body 30 rotates with the rotation of the first rotating shaft body 10 based on the meshing between the first gear 10a and the second gear 20a and the meshing between the second gear 20a and the third gear 30a.

[0082] In the present embodiment, as shown in FIG. 4B, the second permanent magnet 21 is provided at the end of the second rotating shaft body 20 on the same −Y side as the end of the first rotating shaft body 10 on which the first permanent magnet 11 is provided. However, this is not limited to this. As in the encoder 3 according to the modified example 2 shown in FIG. 12, the second permanent magnet 21 may be provided at the end of the second rotating shaft body 20 on the +Y side opposite to the end of the first rotating shaft body 10 on which the first permanent magnet 11 is provided. Similarly, the third permanent magnet 31 may be provided at the end of the third rotating shaft body 30 on the +Y side opposite to the end of the first rotating shaft body 10 on which the first permanent magnet 11 is provided.

[0083] In this embodiment, as shown in FIG. 4B, the first permanent magnet 11 is provided so that a part of it is exposed from the end of the first rotating shaft body 10. However, this is not limited to this. As in the encoder 4 according to the modified example 3 shown in FIG. 13, the first permanent magnet 11 may be embedded in the end of the first rotating shaft body 10 as long as the magnetic flux from the first permanent magnet 11 embedded in the first rotating shaft body 10 leaks out to an extent that can be detected by the sensor S1 with sufficient accuracy. In this case, the first permanent magnet 11 is disposed in a non-exposed state from the end of the first rotating shaft body 10. Similarly, the second permanent magnet 21 and the third permanent magnet 31 may also be disposed in a non-exposed state from the end of the second rotating shaft body 20 and the end of the third rotating shaft body 30 as long as the magnetic flux from the second and third permanent magnets 21 and 31 embedded in the second and third rotating shaft bodies 20 and 30 leaks out to an extent that can be detected by the sensors S2 and S3 with sufficient accuracy.

[0084] Moreover, as shown in FIG. 4(B), the encoder 1 according to the present embodiment includes three rotating shaft bodies, a first rotating shaft body 10, a second rotating shaft body 20, and a third rotating shaft body 30. However, the number of rotating shaft bodies is not limited to this. The encoder 1 may include only two of the first rotating shaft body 10 and the second rotating shaft body 20, or may include only one first rotating shaft body 10. Furthermore, as in Modification 4 shown in FIG. 14, the encoder 5 may further include a fourth rotating shaft body 120 in addition to the first rotating shaft body 10, the second rotating shaft body 20, and the third rotating shaft body 30. Furthermore, the encoder may include five or more rotating shaft bodies.

[0085] In the encoder 1 according to the embodiment and the encoder 2 according to the modified example 1, the first rotating shaft body 10, the second rotating shaft body 20, and the third rotating shaft body 30 are arranged in a row along a straight line L7 that passes through the central axis A of the first rotating shaft body 10 and is perpendicular to the Y-axis direction, as shown in FIG. 4(A). However, this is not limited to this. One or two of the first rotating shaft body 10, the second rotating shaft body 20, and the third rotating shaft body 30 may be arranged off the straight line L7. For example, as in the encoder 6 according to the modified example 5 shown in FIG. 15 and FIG. 16, only the third rotating shaft body 30 may be arranged off the straight line L7. In this case, the size of the encoder 6 can be reduced by reducing the angle θ between the straight line L7 and the straight line L8 that passes through both the central axis A-2 of the third rotating shaft body 30 and the central axis of the second rotating shaft body and is perpendicular to the Y-axis direction.

[0086] Specifically, the overlapping length (overlapping amount) L9 between the first rotating shaft body 10 and the second rotating shaft body 20 in the Z-axis direction on the XZ plane can be increased. Similarly, the overlapping length (overlapping amount) L10 between the second rotating shaft body 20 and the third rotating shaft body 30 in the Z-axis direction can be increased. By increasing the overlapping lengths (overlapping amount) L9, L10, the length L11 from the +Z side end of the first rotating shaft body 10 to the -Z side end of the third rotating shaft body 30 in the Z-axis direction on the XZ plane can be reduced.

[0087] Also, the overlapping length (overlapping amount) L12 between the second rotating shaft body 20 and the first rotating shaft body 10 in the X-axis direction on the XZ plane can be increased. Similarly, the overlapping length (overlapping amount) L13 between the first rotating shaft body 10 and the third rotating shaft body 30 in the X-axis direction can be increased. By increasing the overlapping lengths (overlapping amounts) L12 and L13, the length L14 from the -X side end of the second rotating shaft body 20 to the +X side end of the third rotating shaft body 30 in the X-axis direction on the XZ plane can be reduced.

[0088] Since the lengths L11 and L14 can be reduced, the size of the encoder 6 can be reduced as a result.

[0089] In the encoder 1 according to the embodiment, the end faces on the -Y side of the first permanent magnet 11, the first rotating shaft body 10, and the first bearing 12 are configured to be substantially flush, as shown in Fig. 4. However, this is not limited to this. For example, at least one of the ends on the -Y side of the first bearing 12 and the first rotating shaft body 10 may protrude further toward the -Y side (sensor S1 side) than the end of the first permanent magnet 11.

[0090] 17, the -Y side end of the first bearing 12 may protrude toward the -Y side (sensor S1 side) further than the -Y side ends of the first permanent magnet 11 and the first rotating shaft body 10. With this configuration, the -Y side ends of the first permanent magnet 11 and the first rotating shaft body 10 are formed to be recessed from the -Y side end of the first bearing 12.

[0091] In the encoder 7, the magnetic flux of the first permanent magnet 11 is prevented from leaking toward the sensors S2 and S3, thereby making it possible to further improve the effect of suppressing magnetic interference.

[0092] 18, the -Y side end of the first rotating shaft body 10 may protrude further toward the -Y side (sensor S1 side) than the -Y side end of the first permanent magnet 11. In the encoder 8, the -Y side end of the first rotating shaft body 10 and the -Y side end of the first bearing 12 are configured to be substantially flush with each other. With this configuration, the -Y side end of the first permanent magnet 11 is formed to be recessed from the -Y side ends of the first bearing 12 and the first rotating shaft body 10.

[0093] In the encoder 8, the magnetic flux of the first permanent magnet 11 is prevented from leaking toward the sensors S2 and S3, thereby making it possible to further improve the effect of suppressing magnetic interference.

[0094] The same applies to the relationship between the positions of the ends of the second permanent magnet 21, the second rotating shaft body 20, and the second bearing 22-1, and the relationship between the positions of the ends of the third permanent magnet 31, the third rotating shaft body 30, and the third bearing 32-1. Therefore, in the encoders 7 and 8, the magnetic flux of the second permanent magnet 21 and the magnetic flux of the third permanent magnet 31 are prevented from leaking toward other sensors, which means that the magnetic interference suppression effect can be further improved.

[0095] 1 and 2, the actuator 100 according to the embodiment is a slider-type actuator in which a slide cover C moves in a linear motion direction D1. However, this is not limited to this. The actuator 100 may be a rod-type actuator in which a rod moves in a linear motion direction D1.

[0096] Moreover, the actuator 100 according to the embodiment includes a ball screw 70. The actuator 100 converts the rotational motion of the output shaft 61a of the motor unit 60 into the linear motion of the moving body 90 based on the screw engagement between the ball screw shaft 71 of the ball screw 70 and the ball screw nut 72. However, the structure and shape of the actuator 100 are not limited thereto. For example, the actuator 100 may include a timing belt and a timing pulley that transmit the rotational motion of the output shaft 61a to the moving body 90, instead of the ball screw 70.

[0097] The present invention allows various embodiments and modifications without departing from the broad spirit and scope of the present invention. The above-described embodiments are for explaining the present invention and do not limit the scope of the present invention. [Explanation of symbols]

[0098] 1,1A,2,3,4,5,6: Encoder 10: First rotating shaft 10-1: Cylindrical member 10-2: Cylindrical member 10a: 1st gear 10b: Through hole 11: First permanent magnet 12: First bearing 12a: End face 20: Second rotating shaft 20-1: Cylindrical member 20-2: Cylindrical member 20a: 2nd gear 20b: Through hole 21: Second permanent magnet 22-1, 22-2: Second bearing 22a: End face 30: Third rotating shaft 30-1: Cylindrical member 30-2: Cylindrical member 30a: 3rd gear 30b: Through hole 31: Third permanent magnet 32-1, 32-2: 3rd bearing 32a: End face 40: Case 41: First case part 41a: Through hole 41b: screw hole 42: Second case part 42a, 42b, 42c: Through hole 42d: Screw hole 43: Third case part 43a, 43b, 43c: Through hole 43d: Screw hole 44, 45: Clasp 50: Sensor unit 51: Circuit board 52a:CPU 52b: Communication element 53: Support member 54: Connector 60: Motor unit 61: Motor body (motor) 61a: Output shaft (rotating shaft) 62: Motor casing 63: 1st coupling 70: Ball screw 71: Ball screw shaft 71a: Ball screw shaft body 71b, 71c: End 72: Ball screw nut 73: 2nd coupling 80: Actuator housing 81: Bass 82: Ball screw nut 82R, 82L: Side cover 82a: Opening part 83: Sheet material 84: Front bracket 84a: Bearing 85: Rear bracket 85a: Bearing 90: Mobile 91:Through hole 100: Actuator 110: Magnetic shielding member 120: 4th rotating shaft 200: Controller S1: Sensor (first sensor) S2: Sensor (second sensor) S3: Sensor (third sensor) C: Slide cover D1: Direction of linear motion L1,L2,L3,L4,L5,L6,L9,L10,L11,L12,L13,L14:Length L7,L8: Straight line A,A-2: Central axis P: Same side θ: Angle

Claims

1. An encoder for detecting rotation of an output shaft of a motor, a first rotating shaft body connected to an end of the output shaft and rotating in accordance with the rotation of the output shaft; a first permanent magnet provided at an end of the first rotating shaft; a case that houses the first rotating shaft body; a first sensor disposed opposite the first permanent magnet and configured to detect a change in magnetic flux density of the first permanent magnet in response to rotation of the first rotating shaft body; a first bearing that rotatably supports the first rotating shaft body relative to the case, surrounds the first permanent magnet, and is made of a magnetic shielding material that shields the magnetic field generated by the first permanent magnet; An encoder comprising:

2. a second rotating shaft body that rotates in association with the rotation of the first rotating shaft body; A second permanent magnet provided on the second rotating shaft; a second bearing that rotatably supports the second rotating shaft with respect to the case; a second sensor disposed opposite the second permanent magnet and configured to detect a change in magnetic flux density of the second permanent magnet in response to rotation of the second rotating shaft body; The encoder of claim 1 , comprising:

3. The encoder according to claim 2 , wherein the second bearing is formed from a magnetic shielding material that surrounds the second permanent magnet and shields the magnetic field generated from the second permanent magnet.

4. a third rotating shaft body that rotates in association with the rotation of the first rotating shaft body; A third permanent magnet provided on the third rotating shaft; a third bearing that rotatably supports the third rotating shaft body with respect to the case; a third sensor disposed opposite the third permanent magnet and configured to detect a change in magnetic flux density of the third permanent magnet in response to rotation of the third rotating shaft body; 4. An encoder according to claim 2 or 3, comprising:

5. The encoder according to claim 4 , wherein the third bearing is made of a magnetic shielding material that surrounds the third permanent magnet and shields the magnetic field generated by the third permanent magnet.

6. The first rotating shaft body is provided with a first gear, The second rotating shaft is provided with a second gear with which the first gear meshes, The encoder according to claim 4 , wherein the second rotating shaft body rotates in conjunction with rotation of the first rotating shaft body based on meshing between the first gear and the second gear.

7. The third rotating shaft body is provided with a third gear with which the first gear of the first rotating shaft body meshes, The encoder according to claim 6 , wherein the third rotating shaft body rotates in conjunction with rotation of the first rotating shaft body based on meshing between the first gear and the third gear.

8. The third rotating shaft body is provided with a third gear with which the second gear of the second rotating shaft body meshes, The encoder according to claim 6 , wherein the third rotating shaft body rotates in conjunction with rotation of the first rotating shaft body based on meshing between the first gear and the second gear and meshing between the second gear and the third gear.

9. The second rotating shaft body has an axial direction parallel to the axial direction of the first rotating shaft body, 9. The encoder according to claim 2, wherein the second permanent magnet is provided at an end of the second rotating shaft body on the same side as an end of the first rotating shaft body on which the first permanent magnet is provided.

10. The second rotating shaft body has an axial direction parallel to the axial direction of the first rotating shaft body, 9. The encoder according to claim 2, wherein the second permanent magnet is provided at an end of the second rotating shaft body opposite to an end of the first rotating shaft body at which the first permanent magnet is provided.

11. 11. The encoder according to claim 1, wherein an end of the first bearing in the axial direction of the first rotating shaft body protrudes beyond an end of the first permanent magnet in the axial direction of the first rotating shaft body.

12. The encoder according to claim 1 , wherein an end portion of the first rotating shaft in the axial direction protrudes beyond an end portion of the first permanent magnet in the axial direction of the first rotating shaft.

13. A motor having an output shaft; An encoder according to any one of claims 1 to 12, which detects rotation of the output shaft of the motor; A motor unit comprising:

14. A moving body, The motor unit according to claim 13, wherein the movable body is moved based on rotation of the output shaft; An actuator comprising:

Images