Actuator device

Abstract

To provide an actuator device capable of increasing magnetic flux density in a magnetic boundary of a sensor magnet detected by a magnetic sensor.SOLUTION: One embodiment of an actuator device of the present invention has a drive part movable in a first direction D1, a sensor magnet 45 extending in the first direction which is a magnetization direction and fixed to the drive part, and a magnetic sensor 71 disposed so as to face the sensor magnet in a second direction D2 orthogonal to the first direction and detecting magnetic flux of the sensor magnet. When viewed from the second direction, a width of the sensor magnet in a part where the center of gravity of the sensor magnet is located is wider than that of both ends in the first direction of the sensor magnet.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an actuator device. [Background technology]

[0002] A linear actuator is known in which a magnet is fixed to a support member that moves back and forth, and the position of the support member is controlled based on the magnetic flux of the magnet detected by an IC sensor (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-080131 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the linear actuator described above, the magnetic flux density of the magnet in the magnetization direction is small near the magnetic pole boundary, which is the boundary between a pair of magnetic poles. Therefore, the magnetic flux density detected when the IC sensor faces the vicinity of the magnetic pole boundary of the magnet may be smaller than the lower limit of the magnetic flux density that the IC sensor can detect. In this case, there is a risk that the IC sensor will not be able to accurately detect the position of the magnet and the position of the support member.

[0005] In view of the above circumstances, one aspect of the present invention has an object to provide an actuator device that can increase the magnetic flux density at the magnetic pole boundary of a sensor magnet that is detected by a magnetic sensor. [Means for solving the problem]

[0006] One aspect of the actuator device of the present invention includes a drive unit movable in a first direction, a sensor magnet whose magnetization direction is the first direction and which extends in the first direction and is fixed to the drive unit, and a magnetic sensor disposed opposite the sensor magnet in a second direction intersecting the first direction and which detects the magnetic flux of the sensor magnet. When viewed from the second direction, the width of the sensor magnet at a portion where the center of gravity of the sensor magnet is located is wider than the width of both ends of the sensor magnet in the first direction. Effect of the Invention

[0007] According to one aspect of the present invention, in an actuator device, it is possible to increase the magnetic flux density at the magnetic pole boundary of a sensor magnet detected by a magnetic sensor. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a cross-sectional view showing an actuator device according to one embodiment. [Diagram 2] FIG. 2 is a perspective view showing a part of the actuator device according to the embodiment. [Diagram 3] FIG. 3 is a diagram illustrating an example of the magnetic flux density of a magnet detected by the magnetic sensor of the embodiment. [Figure 4] FIG. 4 is a perspective view showing a part of an actuator device according to a modified example of the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] In each drawing, the first direction D1 is a direction in which the drive unit can move. In the following description, the side toward which the arrow of the first direction D1 points (+D1 side) is called the "lower side," and the side opposite to the side toward which the arrow of the first direction D1 points (-D1 side) is called the "upper side." Note that the upper side and the lower side are names simply for describing the relative positional relationship of each part, and the actual positional relationship, etc. may be a positional relationship, etc. other than the positional relationship, etc. indicated by these names.

[0010] In each drawing, the second direction D2 is a direction that intersects with the first direction D1. In this embodiment, the second direction D2 is perpendicular to the first direction D1. In the following description, the side toward which the arrow of the second direction D2 points (+D2 side) is referred to as "one side of the second direction D2," and the side opposite to the side toward which the arrow of the second direction D2 points (-D2 side) is referred to as "the other side of the second direction D2."

[0011] In each drawing, the third direction D3 is a direction perpendicular to both the first direction D1 and the second direction D2. In this embodiment, the third direction D3 is the width direction of the sensor magnet. In the following description, the side toward which the arrow of the third direction D3 points (+D3 side) is referred to as "one side in the width direction," and the side opposite to the side toward which the arrow of the third direction D3 points (-D3 side) is referred to as "the other side in the width direction."

[0012] The rotation axis J shown in each drawing is a virtual axis extending in a direction parallel to the first direction D1. The rotation axis J is the central axis of the motor shaft. In the following description, the radial direction centered on the rotation axis J is simply referred to as the "radial direction." The circumferential direction centered on the rotation axis J is simply referred to as the "circumferential direction." In each drawing, the circumferential direction is indicated by an arrow θ.

[0013] <Embodiment> 1 is a linear actuator that moves a drive target (not shown) in a first direction D1. The actuator device 10 extends in the first direction D1 as a whole. The actuator device 10 includes a housing 11, a motor unit 20, a drive unit 40, a sensor magnet 45, an output unit 50, a circuit board 70, and a magnetic sensor 71.

[0014] The housing 11 accommodates the motor unit 20, the drive unit 40, the sensor magnet 45, the circuit board 70, and the magnetic sensor 71 therein. The housing 11 has a housing main body 12, a cover member 13, a first bearing holder 14, and a drive unit accommodating member 15. The cover member 13 is fixed to the upper end of the housing main body 12. The first bearing holder 14 is accommodated inside the housing main body 12. The drive unit accommodating member 15 is fixed to the lower end of the housing main body 12.

[0015] The housing body 12 has a generally cylindrical shape extending in a first direction D1 about a rotation axis J. The housing body 12 is open on the upper side. The housing body 12 accommodates the motor section 20 therein. The housing body 12 has a peripheral wall section 12a and a bottom wall section 12d.

[0016] The peripheral wall portion 12a has a generally cylindrical shape extending in the first direction D1 around the rotation axis J. The peripheral wall portion 12a surrounds the motor portion 20 from the radially outer side. The upper end of the peripheral wall portion 12a is the upper end of the housing main body portion 12. The peripheral wall portion 12a has an opening portion 12b that opens upward.

[0017] The bottom wall portion 12d is a plate-like portion extending in a direction perpendicular to the first direction D1. A radial outer edge of the bottom wall portion 12d is connected to a lower end of the peripheral wall portion 12a. The bottom wall portion 12d separates the inside of the housing body portion 12 from the inside of the drive unit accommodating member 15. The bottom wall portion 12d is provided with a second bearing holding portion 12e, a through hole 12f, and an insertion hole 12g.

[0018] The second bearing retaining portion 12e protrudes upward from the bottom wall portion 12d. The second bearing retaining portion 12e has a substantially cylindrical shape centered on the rotation axis J. The second bearing retaining portion 12e opens upward. The second bearing 62 is retained on the inner circumferential surface of the second bearing retaining portion 12e.

[0019] Each of the through hole 12f and the insertion hole 12g is a hole that penetrates the bottom wall portion 12d in the first direction D1. When viewed from the first direction D1, the through hole 12f has a substantially circular shape centered on the rotation axis J. The inner diameter of the through hole 12f is smaller than the inner diameter of the second bearing holder 12e. The insertion hole 12g is provided in an edge portion on one side (+D2 side) of the bottom wall portion 12d in the second direction D2.

[0020] The lid member 13 is in the shape of a disk centered on the rotation axis J. The plate surface of the lid member 13 faces the first direction D1. The lid member 13 is fixed to the upper end of the peripheral wall portion 12a. The lid member 13 closes the opening 12b from above.

[0021] The first bearing retaining portion 14 has a substantially circular ring shape centered on the rotation axis J. The outer peripheral surface of the first bearing retaining portion 14 is fixed to the inner peripheral surface of the peripheral wall portion 12a. In this way, the first bearing retaining portion 14 is fixed to the housing main body 12. The first bearing 61 is retained on the inner peripheral surface of the first bearing retaining portion 14.

[0022] The drive unit housing member 15 has a generally cylindrical shape extending in the first direction D1 around the rotation axis J. The drive unit housing member 15 is open on the upper side. The drive unit housing member 15 houses the drive unit 40, the sensor magnet 45, the output unit 50, the circuit board 70, and the magnetic sensor 71 therein. The drive unit housing member 15 has an annular wall portion 15a and a bottom portion 15d.

[0023] The annular wall portion 15a is substantially cylindrical and extends in the first direction D1 with the rotation axis J as the center. The annular wall portion 15a surrounds the driving unit 40, the sensor magnet 45, the output unit 50, the circuit board 70, and the magnetic sensor 71 from the radially outer side. The annular wall portion 15a opens upward. The annular wall portion 15a is provided with a plurality of board holding portions 15b. Each board holding portion 15b is columnar and protrudes from one side (+D2 side) of the annular wall portion 15a in the second direction D2 toward the other side (-D2 side) in the second direction D2. Each board holding portion 15b holds the circuit board 70.

[0024] The bottom portion 15d is a plate-like member that extends in a direction perpendicular to the first direction D1. The radial outer edge of the bottom portion 15d is connected to the lower end of the annular wall portion 15a. The bottom portion 15d is provided with a sealing member holding portion 15e and a bottom through-hole 15f.

[0025] The sealing member holding portion 15e protrudes downward from the bottom portion 15d. The sealing member holding portion 15e has a substantially annular shape centered on the rotation axis J. The sealing member holding portion 15e opens downward. The sealing member 63 is held on the inner surface of the sealing member holding portion 15e.

[0026] The bottom through hole 15f is a hole that penetrates the bottom 15d in the first direction D1. When viewed from the first direction D1, the bottom through hole 15f has a substantially circular shape centered on the rotation axis J. The inner diameter of the bottom through hole 15f is smaller than the inner diameter of the sealing member holding portion 15e.

[0027] The motor unit 20 is accommodated inside the housing main body 12. The motor unit 20 has a rotor 21 and a stator 30. In this embodiment, the motor unit 20 drives the rotor 21 to rotate about a rotation axis J by a current supplied from a circuit board 70, and transmits the power of the rotor 21 to the drive unit 40.

[0028] The rotor 21 is rotatable about the rotation axis J. The rotor 21 has a rotor core 22, a plurality of rotor magnets 23, and a shaft 24. That is, the motor section 20 has the shaft 24. The rotor core 22 is annular about the rotation axis J. Each of the plurality of rotor magnets 23 is fixed to the rotor core 22. The rotor magnets 23 are arranged at intervals from one another along the circumferential direction.

[0029] The shaft 24 is substantially cylindrical and extends in the first direction D1 around the rotation axis J. The shaft 24 extends in the first direction D1 across the inside of the housing main body 12 and the inside of the drive unit accommodating member 15. The shaft 24 passes through the inside of the rotor core 22 in the first direction D1. The rotor core 22 is fixed to the outer circumferential surface of the shaft 24. A portion of the shaft 24 above the rotor core 22 is supported by a first bearing 61 so as to be rotatable around the rotation axis J. A portion of the shaft 24 below the rotor core 22 is supported by a second bearing 62 so as to be rotatable around the rotation axis J. As a result, the shaft 24 is rotatable around the rotation axis J. The lower end of the shaft 24 passes through the through hole 12f in the first direction D1 and protrudes into the inside of the drive unit accommodating member 15. A second screw portion 24a is provided on the shaft 24. The second screw portion 24a is a male screw provided on a portion of the outer circumferential surface of the shaft 24 that is located inside the drive unit accommodating member 15.

[0030] The first bearing 61 and the second bearing 62 are annular about the rotation axis J. As described above, the first bearing 61 is held by the inner circumferential surface of the first bearing holder 14. The second bearing 62 is held by the inner circumferential surface of the second bearing holder 12e. As described above, the first bearing 61 and the second bearing 62 support the shaft 24 rotatably about the rotation axis J. In this embodiment, the first bearing 61 and the second bearing 62 are ball bearings. The first bearing 61 and the second bearing 62 may be slide bearings.

[0031] The stator 30 is disposed radially outward of the rotor 21. The stator 30 is disposed radially opposite the rotor 21 with a gap therebetween. The stator 30 includes a stator core 31, an insulator 32, and a coil portion 33.

[0032] The stator core 31 is annular and surrounds the rotor core 22 from the radial outside. The stator core 31 faces the rotor 21 with a gap in the radial direction. The stator core 31 is fixed to the inner circumferential surface of the peripheral wall portion 12a. This fixes the stator 30 to the housing 11. The insulator 32 is attached to the stator core 31. The insulator 32 insulates the stator core 31 from the coil portion 33.

[0033] The coil portion 33 has a plurality of coil body portions 33a and a coil lead wire 33b. Each coil body portion 33a is attached to the stator core 31 via an insulator 32. Each coil body portion 33a is arranged at intervals along the circumferential direction. The coil lead wire 33b is drawn downward from the coil body portion 33a and connected to the circuit board 70. This electrically connects the coil portion 33 to the circuit board 70. When a current is supplied from the circuit board 70 to the coil portion 33, the rotor 21 rotates around the rotation axis J. The circuit board 70 can control the rotation speed, rotation direction, etc. of the rotor 21 by controlling the current supplied to the coil portion 33. The circuit board 70 can control the movement speed and movement direction of the drive portion 40 in the first direction D1 by controlling the rotation speed, rotation direction, etc. of the rotor 21.

[0034] The drive unit 40 is accommodated inside the drive unit accommodating member 15. The drive unit 40 is connected to a portion of the shaft 24 that is located inside the drive unit accommodating member 15. The drive unit 40 converts the rotational motion of the motor unit 20 into linear motion and transmits the linear motion to the output unit 50. The drive unit 40 is cylindrical and extends in the first direction D1. The drive unit 40 surrounds the rotation axis J. The drive unit 40 has a cylindrical portion 41 and a protruding portion 42.

[0035] The cylindrical portion 41 is substantially cylindrical and extends in the first direction D1 around the rotation axis J. The cylindrical portion 41 is open on both sides in the first direction D1. A portion of the shaft 24 located inside the drive unit housing member 15 is inserted into the cylindrical portion 41. The lower end of the cylindrical portion 41 protrudes to the outside of the actuator device 10 through the bottom through-hole 15f. The cylindrical portion 41 is provided with a first screw portion 41a that meshes with the second screw portion 24a. The first screw portion 41a is a female screw provided on the inner circumferential surface of the cylindrical portion 41.

[0036] The protruding portion 42 protrudes from the cylindrical portion 41 to one side (+D2 side) in the second direction D2. The protruding portion 42 faces the circuit board 70 with a gap therebetween in the second direction D2. A sensor magnet 45 is fixed to an end of the protruding portion 42 on one side in the second direction D2.

[0037] The output section 50 is fixed to the lower end of the cylindrical section 41. The output section 50 is located outside the housing 11. The output section 50 has an output main body section 51 and an output protruding section 52. The output main body section 51 is plate-shaped protruding in the first direction D1. In this embodiment, the output main body section 51 is substantially rectangular plate-shaped extending in a direction perpendicular to the third direction D3. The output main body section 51 is provided with a mounting hole 53. The mounting hole 53 is a hole penetrating the output main body section 51 in the third direction D3. The output protruding section 52 protrudes upward from the upper end of the output main body section 51. The output protruding section 52 is substantially circular plate-shaped with the rotation axis J as its center. The output protruding section 52 is located inside the cylindrical section 41. The output protruding section 52 is fixed to the inner circumferential surface of the cylindrical section 41. As a result, the output section 50 is fixed to the drive section 40.

[0038] A drive target (not shown) that is moved in the first direction D1 by the actuator device 10 is attached to the attachment hole 53. By attaching the drive target to the attachment hole 53, the output unit 50 is restrained from rotating about the rotation axis J. As a result, the drive unit 40 fixed to the output unit 50 is also restrained from rotating about the rotation axis J.

[0039] When a current is supplied from the circuit board 70 to the stator 30 and the shaft 24 rotates around the rotation axis J, the second screw portion 24a of the shaft 24 rotates relative to the first screw portion 41a of the drive unit 40 around the rotation axis J. As described above, the rotation of the drive unit 40 around the rotation axis J is suppressed. Therefore, when the shaft 24 rotates around the rotation axis J, the first screw portion 41a is sent in the first direction D1 relative to the second screw portion 24a. This allows the drive unit 40 to move in the first direction D1. When the drive unit 40 moves in the first direction D1, the output unit 50 fixed to the drive unit 40 moves in the first direction D1. This allows the actuator device 10 to move a drive target (not shown) in the first direction D1.

[0040] According to this embodiment, the driving unit 40 is cylindrical and extends in the first direction D1, with the first threaded portion 41a provided on the inner peripheral surface, and the second threaded portion 24a that meshes with the first threaded portion 41a is provided on the outer peripheral surface of the shaft 24. Thus, the rotational motion of the shaft 24 about the rotation axis J can be converted into the linear motion of the driving unit 40 in the first direction D1 only by the first threaded portion 41a provided on the driving unit 40 and the second threaded portion 24a provided on the shaft 24. Therefore, since no separate member is required for converting the rotational motion of the shaft 24 into the linear motion of the driving unit 40, an increase in the number of parts and manufacturing costs of the actuator device 10 can be suppressed.

[0041] The sealing member 63 is held on the inner circumferential surface of the sealing member holding portion 15e. In this embodiment, the sealing member 63 is a lip seal having a lip portion on the radially inner side. The lip portion of the sealing member 63 contacts the outer circumferential surface of the cylindrical portion 41 of the drive unit 40. In this way, the sealing member 63 seals between the drive unit 40 and the housing 11.

[0042] The circuit board 70 is a plate-like shape that extends in a direction perpendicular to the second direction D2. The plate surface of the circuit board 70 faces the second direction D2. The circuit board 70 is disposed on one side (+D2 side) of the sensor magnet 45 in the second direction D2. The circuit board 70 faces the sensor magnet 45 at an interval in the second direction D2. Although not shown, the circuit board 70 has a plurality of board holes that penetrate the circuit board 70 in the second direction D2. Different board holders 15b are inserted into each board hole. The board holders 15b are fixed to the inner circumferential surface of each board hole. This fixes the circuit board 70 to the housing 11. A magnetic sensor 71 is mounted on a surface of the circuit board 70 facing the other side (-D2 side) of the second direction D2.

[0043] The magnetic sensor 71 is a sensor capable of detecting the magnetic flux of the sensor magnet 45 fixed to the protruding portion 42 of the driving unit 40. The magnetic sensor 71 is disposed at an interval from the sensor magnet 45 in the second direction D2. In the second direction D2, the magnetic sensor 71 is disposed facing the sensor magnet 45. In this embodiment, the magnetic sensor 71 is a magnetic sensor including a Hall element such as a Hall IC. The magnetic sensor 71 may be a magnetic sensor including an MR (Magnetic Resistance) sensor element. The circuit board 70 is capable of detecting the position of the sensor magnet 45 in the first direction D1 by the magnetic flux of the sensor magnet 45 detected by the magnetic sensor 71. This allows the circuit board 70 to detect the positions of the driving unit 40 and the output unit 50 in the first direction D1. The circuit board 70 controls the motor unit 20 based on the magnetic flux of the sensor magnet 45 detected by the magnetic sensor 71. More specifically, the circuit board 70 controls the current supplied to the stator 30 based on the magnetic flux of the sensor magnet 45 detected by the magnetic sensor 71. In this way, the circuit board 70 controls the rotation speed, rotation direction, etc. of the rotor 21 to determine the position of the drive unit 40 in the first direction D1.

[0044] According to this embodiment, the actuator device 10 includes a circuit board 70 on which a magnetic sensor 71 is mounted, and the circuit board 70 controls the motor unit 20 based on the magnetic flux of the sensor magnet 45 detected by the magnetic sensor 71. Since the magnetic sensor 71 is mounted on the circuit board 70, there is no need to provide a separate signal line for electrically connecting the magnetic sensor 71 and the circuit board 70. This makes it possible to suppress an increase in the number of components of the actuator device 10. In addition, since there is no need for a man-hour for connecting a signal line to each of the magnetic sensor 71 and the circuit board 70, an increase in the number of man-hours required for manufacturing the actuator device 10 can be suppressed.

[0045] As described above, the sensor magnet 45 is fixed to an end portion on one side (+D2 side) in the second direction D2 of the protrusion 42. More specifically, the sensor magnet 45 is fixed to a surface of the outer surface of the protrusion 42 facing one side in the second direction D2. The sensor magnet 45 is movable in the first direction D1 together with the driving unit 40. The sensor magnet 45 faces the magnetic sensor 71 with a gap therebetween in the second direction D2.

[0046] As shown in FIG. 2, the sensor magnet 45 extends in the first direction D1. The sensor magnet 45 has the magnetization direction in the first direction D1. In this embodiment, the south pole portion 45S of the sensor magnet 45 is the lower part of the sensor magnet 45. The north pole portion 45N of the sensor magnet 45 is the upper part of the sensor magnet 45. The south pole portion 45S may be the upper part of the sensor magnet 45, and the north pole portion 45N may be the lower part of the sensor magnet 45. When viewed from the second direction D2, the width of the sensor magnet 45 becomes wider from each of the ends on both sides of the first direction D1 toward the center of the first direction D1. In this embodiment, the sensor magnet 45 has a plane-symmetric shape with respect to a plane that passes through the center of the first direction D1 of the sensor magnet 45 and extends in a direction perpendicular to the first direction D1. The sensor magnet 45 does not have to have a plane-symmetric shape with respect to a plane that passes through the center of the first direction D1 of the sensor magnet 45 and extends in a direction perpendicular to the first direction D1. The center of gravity 45c of the sensor magnet 45 is located at the center of the sensor magnet 45 in the first direction D1. In the first direction D1, the center of gravity 45c of the sensor magnet 45 may be located at a position other than the center of the sensor magnet 45 in the first direction D1. When viewed from the second direction D2, the width of the sensor magnet 45 at the portion where the center of gravity 45c of the sensor magnet 45 is located is wider than the width of both ends of the sensor magnet 45 in the first direction D1. A magnetic pole boundary 45e, which is a boundary between the south pole portion 45S and the north pole portion 45N, passes through the center of gravity 45c.

[0047] In this embodiment, when viewed from the second direction D2, both ends of the sensor magnet 45 in the width direction (third direction D3) are curved. More specifically, both ends of the sensor magnet 45 in the width direction are curved with the center in the first direction D1 protruding outward in the width direction. In addition, each of the surface 45a facing one side (+D2 side) of the second direction D2 and the surface 45b facing the other side (-D2 side) of the second direction D2 of the sensor magnet 45 is flat. That is, the surfaces 45a and 45b of the sensor magnet 45 facing the second direction D2 are flat surfaces parallel to each other. Therefore, according to this embodiment, the sensor magnet 45 can be prevented from becoming large in the second direction D2, compared to a case in which the surfaces 45a and 45b of the sensor magnet 45 facing the second direction D2 are curved surfaces protruding in the second direction D2. Therefore, the actuator device 10 can be prevented from becoming large in the second direction D2.

[0048] FIG. 3 is a diagram showing the relationship between the position of the sensor magnet 45 in the first direction D1 and the magnetic flux density of the sensor magnet 45 detected by the magnetic sensor 71. The horizontal axis of FIG. 3 is the magnetic distance Dm, which is the distance between the magnetic sensor 71 and the magnetic pole boundary 45e of the sensor magnet 45 in the first direction D1. When the magnetic distance Dm is 0, the magnetic sensor 71 faces the magnetic pole boundary 45e of the sensor magnet 45 in the second direction D2. When the magnetic distance Dm is positive, the magnetic pole boundary 45e is located below the magnetic sensor 71. When the magnetic distance Dm is negative, the magnetic pole boundary 45e is located above the magnetic sensor 71. The vertical axis of FIG. 3 is the detected magnetic flux density Bd, which is the magnetic flux density of the sensor magnet 45 detected by the magnetic sensor 71. The detectable magnetic flux density Bu shown in FIG. 3 is the lower limit of the magnetic flux density that the magnetic sensor 71 can detect. When the detected magnetic flux density Bd becomes smaller than the detectable magnetic flux density Bu, the detection accuracy of the magnetic flux density of the magnetic sensor 71 decreases. This reduces the detection accuracy of the position of the drive unit 40 in the first direction D1 detected by the circuit board 70, and therefore the accuracy with which the circuit board 70 determines the position of the drive unit 40 in the first direction D1 deteriorates.

[0049] First, the detected magnetic flux density Bd of the sensor magnet of the comparative example of this embodiment will be described. In FIG. 3, the detected magnetic flux density Bd of the sensor magnet of the comparative example is indicated by a broken line. Although not shown, the sensor magnet of the comparative example is a rectangular parallelepiped extending in the first direction D1. When viewed from the second direction D2, the sensor magnet of the comparative example is a rectangular shape. The volume of the sensor magnet of the comparative example is the same as the volume of the sensor magnet 45 of this embodiment. Other configurations of the sensor magnet of the comparative example are similar to those of the sensor magnet 45 of this embodiment. As shown in FIG. 3, in the sensor magnet of the comparative example, the detected magnetic flux density Bd decreases from each of both ends of the first direction D1 toward the center of the first direction D1. When the magnet distance Dm is 0 and near 0, that is, when the magnetic sensor 71 faces the magnetic pole boundary and the vicinity of the magnetic pole boundary of the sensor magnet in the second direction D2, the detected magnetic flux density Bd is smaller than the detectable magnetic flux density Bu. Therefore, in the case of the rectangular parallelepiped sensor magnet of the comparative example, in order to make the detected magnetic flux density Bd at the magnetic pole boundary and in the vicinity of the magnetic pole boundary of the sensor magnet larger than the detectable magnetic flux density Bu, the sensor magnet itself needs to be enlarged. This increases the manufacturing cost of the sensor magnet and the size of the actuator device 10. In the following description, the portion of the sensor magnet at the magnetic pole boundary and in the vicinity of the magnetic pole boundary may be simply referred to as the "vicinity of the magnetic pole boundary."

[0050] Next, the detected magnetic flux density Bd of the sensor magnet 45 of this embodiment will be described. In Fig. 3, the detected magnetic flux density Bd of the sensor magnet 45 is indicated by a solid line. As with the sensor magnet of the comparative example, the detected magnetic flux density Bd of the sensor magnet 45 also decreases from both ends of the first direction D1 toward the center of the first direction D1. However, in the sensor magnet 45 of this embodiment, the detected magnetic flux density Bd detected when the magnetic sensor 71 faces the vicinity of the magnetic pole boundary 45e in the second direction D2 is greater than the detectable magnetic flux density Bu.

[0051] According to this embodiment, the actuator device 10 includes a sensor magnet 45 having a magnetization direction in the first direction D1, extending in the first direction D1, and fixed to the driving unit 40, and a magnetic sensor 71 disposed opposite the sensor magnet 45 in the second direction D2 to detect the magnetic flux of the sensor magnet 45. The width of the sensor magnet 45 at the portion where the center of gravity 45c of the sensor magnet 45 is located as viewed from the second direction D2 is wider than the width of both ends of the sensor magnet 45 in the first direction D1. Therefore, compared with the sensor magnet of the comparative example having a rectangular shape as viewed from the second direction D2, the sensor magnet 45 of this embodiment is easy to increase the volume in the vicinity of the magnetic pole boundary 45e. Therefore, the sensor magnet 45 of this embodiment can increase the magnetic flux density in the vicinity of the magnetic pole boundary 45e. Therefore, as shown in FIG. 3, in this embodiment, the sensor magnet 45 can be prevented from becoming large, while the detected magnetic flux density Bd in the vicinity of the magnetic pole boundary 45e can be increased. Therefore, the detected magnetic flux density Bd in the vicinity of the magnetic pole boundary 45e can be made larger than the detectable magnetic flux density Bu. As a result, the magnetic sensor 71 can accurately detect the magnetic flux density in the vicinity of the magnetic pole boundary 45e, and the accuracy with which the circuit board 70 detects the position of the drive unit 40 in the first direction D1 can be improved. Therefore, the circuit board 70 can accurately determine the position of the drive unit 40 in the first direction D1. Furthermore, since the sensor magnet 45 can be prevented from becoming large, an increase in the manufacturing cost of the sensor magnet 45 can be prevented, and an increase in the size of the actuator device 10 can be prevented.

[0052] According to this embodiment, when viewed from the second direction D2, both ends of the sensor magnet 45 in the width direction (third direction D3) are curved. Therefore, as shown in FIG. 3, it is easy to make the detected magnetic flux density Bd with respect to the magnet distance Dm into a smooth curve. This allows the circuit board 70 to accurately detect the position of the drive unit 40 in the first direction D1 based on the detection result of the magnetic sensor 71, compared to a case where the detected magnetic flux density Bd with respect to the magnet distance Dm changes sharply. Therefore, the circuit board 70 can more accurately determine the position of the drive unit 40 in the first direction D1.

[0053] <Modification> 4 is a perspective view showing a part of an actuator device 110 of this modified example. In the following description, the same components as those in the above-described embodiment are denoted by the same reference numerals, and the description thereof may be omitted.

[0054] As shown in FIG. 4, when viewed from the second direction D2, the end of the sensor magnet 145 on one side (+D3 side) in the width direction of the present modification is curved, and the end of the sensor magnet 145 on the other side (-D3 side) in the width direction is straight. The sensor magnet 145 has a magnetization direction in the first direction D1. In this modification, the S pole portion 145S of the sensor magnet 145 is a lower part of the sensor magnet 145. The N pole portion 145N of the sensor magnet 145 is an upper part of the sensor magnet 145. When viewed from the second direction D2, the width of the sensor magnet 145 becomes wider from each of the ends on both sides in the first direction D1 toward the center of the first direction D1. In this embodiment, the center of gravity 145c of the sensor magnet 145 is located at the center of the sensor magnet 145 in the first direction D1. In the first direction D1, the center of gravity 145c of the sensor magnet 145 may be located other than the center of the sensor magnet 145 in the first direction D1. A magnetic pole boundary 145e, which is the boundary between the south pole portion 145S and the north pole portion 145N, passes through the center of gravity 145c.

[0055] Although not shown in the figures, the detected magnetic flux density Bd of the sensor magnet 145 of this modified example is the same as the detected magnetic flux density Bd of the sensor magnet 45 of the above-mentioned embodiment. That is, when the magnet distance Dm is near 0, that is, when the magnetic sensor 71 faces the vicinity of the magnetic pole boundary 145e in the second direction D2, the detected magnetic flux density Bd is greater than the detectable magnetic flux density Bu. Therefore, according to this modified example, the magnetic sensor 71 can accurately detect the magnetic flux density near the magnetic pole boundary 145e, so that the accuracy with which the circuit board 70 detects the position of the drive unit 40 in the first direction D1 can be improved. Therefore, the circuit board 70 can accurately determine the position of the drive unit 40 in the first direction D1. Also, as in the above-mentioned embodiment, the sensor magnet 145 can be prevented from becoming large, so that the manufacturing cost of the sensor magnet 145 can be prevented from increasing and the actuator device 110 can be prevented from becoming large.

[0056] According to this modification, when viewed from the second direction D2, the end of the sensor magnet 145 on one side (+D3 side) in the width direction is curved, and the end of the sensor magnet 145 on the other side (-D3 side) in the width direction is linear. Therefore, similar to the above-mentioned embodiment, it is easy to make the detected magnetic flux density Bd with respect to the magnet distance Dm a smooth curve. As a result, compared to a case where the detected magnetic flux density Bd with respect to the magnet distance Dm changes sharply, the circuit board 70 can accurately detect the position of the drive unit 40 in the first direction D1 based on the detection result of the magnetic sensor 71. Therefore, the circuit board 70 can more accurately determine the position of the drive unit 40 in the first direction D1.

[0057] The present invention is not limited to the above-described embodiment, and other configurations and methods may be adopted within the scope of the technical idea of ​​the present invention. For example, the width of the sensor magnet as viewed from the second direction may be linearly increased from both ends in the first direction toward the center in the first direction.

[0058] The magnetic sensor may be mounted on a substrate different from the circuit board, in which case the substrate and the circuit board are electrically connected to each other via a signal line or the like.

[0059] The use of the actuator device to which the present invention is applied is not particularly limited. The actuator device may be mounted on any type of equipment. For example, the actuator device may be mounted on a vehicle. Note that the configurations described above in this specification may be appropriately combined within a range that does not contradict each other.

[0060] The present technology can be configured as follows. (1) An actuator device comprising: a driving unit movable in a first direction; a sensor magnet whose magnetization direction is the first direction, extending in the first direction, and fixed to the driving unit; and a magnetic sensor arranged opposite the sensor magnet in a second direction intersecting the first direction and detecting magnetic flux of the sensor magnet, wherein when viewed from the second direction, the width of the sensor magnet at a portion where the center of gravity of the sensor magnet is located is wider than the width of both ends of the sensor magnet in the first direction. (2) The actuator device according to (1), wherein the surface of the sensor magnet facing the second direction is flat. (3) The actuator device according to (1) or (2), wherein each of opposite ends of the sensor magnet in the width direction is curved when viewed from the second direction. (4) An actuator device according to (1) or (2), wherein, when viewed from the second direction, one end of the sensor magnet in the width direction is curved and the other end of the sensor magnet in the width direction is straight. (5) An actuator device as described in any one of (1) to (4), further comprising a motor unit having a shaft extending in the first direction and rotatable about a rotation axis extending in a direction parallel to the first direction, the drive unit being cylindrical and having a first threaded portion on its inner surface and a second threaded portion on its outer surface that meshes with the first threaded portion. (6) The actuator device according to (5), further comprising a circuit board on which the magnetic sensor is mounted, the circuit board controlling the motor section based on the magnetic flux of the sensor magnet detected by the magnetic sensor. [Explanation of symbols]

[0061] Reference Signs List 10,110...actuator device, 20...motor section, 24...shaft, 24a...second screw section, 40...drive section, 41a...first screw section, 45,145...sensor magnet, 70...circuit board, 71...magnetic sensor, D1...first direction, D2...second direction

Claims

1. A drive unit movable in a first direction; a sensor magnet whose magnetization direction is the first direction, extends in the first direction, and is fixed to the driving unit; a magnetic sensor disposed opposite the sensor magnet in a second direction intersecting the first direction and configured to detect a magnetic flux of the sensor magnet; Equipped with An actuator device, wherein a width of the sensor magnet at a portion where a center of gravity of the sensor magnet is located when viewed from the second direction is wider than a width of both ends of the sensor magnet in the first direction.

2. The actuator device according to claim 1 , wherein a surface of the sensor magnet facing the second direction is flat.

3. 3. The actuator device according to claim 1, wherein each of opposite ends of the sensor magnet in the width direction is curved when viewed from the second direction.

4. 3 . The actuator device according to claim 1 , wherein, when viewed from the second direction, one end of the sensor magnet in the width direction is curved, and the other end of the sensor magnet in the width direction is straight.

5. a motor unit having a shaft extending in the first direction and rotatable about a rotation axis extending in a direction parallel to the first direction; The drive portion has a cylindrical shape including an inner circumferential surface provided with a first thread portion and extending in the first direction, The actuator device according to claim 1 , wherein a second threaded portion is provided on an outer circumferential surface of the shaft, the second threaded portion meshing with the first threaded portion.

6. a circuit board on which the magnetic sensor is mounted, The actuator device according to claim 5 , wherein the circuit board controls the motor unit based on a magnetic flux of the sensor magnet detected by the magnetic sensor.

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