Electric actuator

Abstract

The utility model provides an electric actuator which can restrain axial upsizing. An electric actuator includes: a motor having a hollow motor shaft rotatable about a motor axis and a rotor fixed to an outer peripheral surface of the motor shaft; a transmission mechanism connected to the motor shaft; an output shaft which extends in the axial direction and to which the rotation of the motor shaft is transmitted via a transmission mechanism; a circuit board disposed closer to one side in the axial direction than the rotor; a first rotating member attached to a portion of the output shaft closer to one side in the axial direction than the motor shaft; and a second rotating member to which the rotation of the first rotating member is transmitted in a decelerated manner, at least a portion of the output shaft is located inside the motor shaft, the second rotating member is disposed further toward one side in the axial direction than the circuit board, and a magnet is fixed to the second rotating member. A magnetic sensor, which is disposed so as to face the magnet in the axial direction, and detects the magnetic flux of the magnet, is mounted on the surface of the circuit board facing the one side in the axial direction.

Description

Technical Field

[0001] The utility model relates to an electric actuator. Background Art

[0002] The following electrically controlled actuator is known: the rotation of the drive shaft is decelerated and transmitted to a detection rotating body via a small gear installed on the end of one axial side of the drive shaft, and the magnetic field of the magnet component of the detection rotating body is detected by a sensor installed on a circuit substrate arranged on the axial side of the magnet component, thereby controlling the rotation of the drive shaft (for example, patent document 1).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2010-263777 Utility Model Content

[0006] Issues to be solved by the utility model

[0007] In the electrically controlled actuator described above, since the magnet member, the sensor, and the circuit board are arranged on one side of the drive shaft in the axial direction, there is a problem that the electrically controlled actuator becomes larger in the axial direction.

[0008] In view of the above situation, one of the objects of the present invention is to provide an electric actuator capable of suppressing axial enlargement.

[0009] Solutions to Problems

[0010] The electric actuator of claim 1 of the present invention is characterized by comprising: a motor having a hollow motor shaft rotatable about a motor axis, and a rotor fixed to an outer peripheral surface of the motor shaft; a transmission mechanism connected to the motor shaft; an output shaft extending in the axial direction, to which the rotation of the motor shaft is transmitted via the transmission mechanism; a circuit board arranged on one axial side of the rotor; a first rotating member mounted on a portion of the output shaft on one axial side of the motor shaft; and a second rotating member to which the rotation of the first rotating member is reduced in speed and transmitted, at least a portion of the output shaft being located inside the motor shaft, the second rotating member being arranged on one axial side of the circuit board, a magnet being fixed to the second rotating member, and a magnetic sensor being mounted on a surface of the circuit board facing one axial side, the magnetic sensor being arranged axially opposite to the magnet and detecting the magnetic flux of the magnet.

[0011] The electric actuator according to claim 2 of the present invention is characterized in that a first gear portion is provided on the radially outer peripheral surface of the first rotating member, and a second gear portion meshing with the first gear portion is provided on the second rotating member.

[0012] The electric actuator according to claim 3 of the present invention is characterized by comprising an annular driving member wound around both the first rotating member and the second rotating member, wherein the rotation of the first rotating member is transmitted to the second rotating member via the driving member.

[0013] The electric actuator according to claim 4 of the present invention is characterized in that the second rotating member is provided with a recessed portion recessed from a surface facing the other axial side toward one axial side, and at least a portion of the magnet is fixed to an inner side surface of the recessed portion.

[0014] The electric actuator of scheme 5 of the present invention is characterized in that it comprises: a housing, which accommodates the above-mentioned motor, the above-mentioned transmission mechanism and the above-mentioned output shaft; and a shaft component, which is retained in the above-mentioned housing and extends axially, and a through hole is provided in the above-mentioned second rotating component, which penetrates the above-mentioned second rotating component in the axial direction, and the above-mentioned shaft component passes through the through hole in the axial direction and supports the above-mentioned second rotating component so that it can rotate.

[0015] The electric actuator of scheme 6 of the present invention is characterized in that a through hole is provided in the above-mentioned magnet and passes through the above-mentioned magnet in the axial direction, the above-mentioned shaft component passes through the above-mentioned through hole in the axial direction, and an anti-slip component is fixed to a portion of the above-mentioned shaft component that is closer to the other axial side than the above-mentioned second rotating component and the above-mentioned magnet, and the outer diameter of the above-mentioned anti-slip component is larger than the inner diameter of the above-mentioned through hole and the inner diameter of the above-mentioned through hole.

[0016] Utility model effect

[0017] According to one aspect of the present invention, in the electric actuator, increase in size in the axial direction can be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a cross-sectional view showing the electric actuator according to the first embodiment.

[0019] Figure 2 This is a diagram showing the transmission mechanism of the first embodiment as viewed from above.

[0020] Figure 3 It is a cross-sectional view showing an electric actuator according to a second embodiment. DETAILED DESCRIPTION

[0021] In the figures, the Z-axis direction is a vertical direction with the positive side (+Z side) as the upper side and the negative side (-Z side) as the lower side. The direction in which the motor axis J1 extends, as shown in the figures, is parallel to the Z-axis direction, or the vertical direction. In the following description, the direction parallel to the direction in which the motor axis J1 extends is simply referred to as the "axial direction." Furthermore, the radial direction centered on the motor axis J1 is simply referred to as the "radial direction," and the circumferential direction centered on the motor axis J1 is simply referred to as the "circumferential direction."

[0022] In this embodiment, the upper side corresponds to "one axial side," and the lower side corresponds to "the other axial side." Furthermore, the terms "upper and lower directions," "upper side," and "lower side" are merely names used to describe the relative positional relationships of various components, and the actual configuration relationships may be other than those indicated by these names.

[0023] <First embodiment>

[0024] Figure 1 The electric actuator 1 of the present embodiment shown is mounted on a vehicle. More specifically, the electric actuator 1 is mounted on, for example, a park-by-wire actuator device that is driven based on a shift operation by the vehicle driver. The electric actuator 1 includes a housing 10, a motor 20, a transmission mechanism 30, an output shaft 46, a first rotating member 71, a second rotating member 72, a shaft member 73, a magnet 45, a circuit board 80, and a magnetic sensor 81.

[0025] The housing 10 houses various components of the electric actuator 1, including the motor 20, the transmission mechanism 30, the output shaft 46, the first rotating member 71, the second rotating member 72, the magnet 45, and the circuit board 80. The housing 10 includes a housing body 11 and a cover member 12. The housing body 11 has, for example, a cylindrical shape centered on the motor axis J1. The housing body 11 is open at the top and has a first housing portion 11a and a second housing portion 11b.

[0026] The first housing portion 11a is the lower portion of the housing body 11. The first housing portion 11a has a bottom portion 11c and a peripheral wall portion 11d extending upward from the radially outer edge of the bottom portion 11c. A hole portion 11e is provided in the bottom portion 11c, extending axially through the bottom portion 11c. The hole portion 11e is a circular hole centered on the motor axis J1. The upper portion of the hole portion 11e constitutes a third bearing retaining portion 11f that retains the third bearing 51. In this embodiment, the third bearing 51 is, for example, a ball bearing.

[0027] The second housing portion 11b is the upper portion of the housing body 11. It is axially connected to the first housing portion 11a. The second housing portion 11b is cylindrical and open at the top. The inner circumference of the second housing portion 11b is provided with a stepped surface 11g facing upward. The circuit board 80 is secured to the stepped surface 11g.

[0028] The cover member 12 is fixed to the upper end of the housing body 11. The cover member 12 closes the upper opening of the housing body 11. The cover member 12 includes a cover body portion 12a that closes the upper opening of the housing body 11, a fourth bearing retaining portion 12b, and a shaft member retaining portion 12d. The fourth bearing retaining portion 12b protrudes downward from the cover body portion 12a. The fourth bearing retaining portion 12b is cylindrical, centered on the motor axis J1, and open at the bottom. The fourth bearing 52 is retained on the inner circumference of the fourth bearing retaining portion 12b. The fourth bearing 52 is, for example, a ball bearing. The shaft member retaining portion 12d protrudes downward from the cover body portion 12a. The shaft member retaining portion 12d is cylindrical, extending axially. The shaft member retaining portion 12d is open at the bottom. The shaft member retaining portion 12d is positioned radially outward of the fourth bearing retaining portion 12b. The shaft member 73 is retained on the inner circumference of the shaft member retaining portion 12d.

[0029] The motor 20 includes a stator 22, a motor shaft 23, and a rotor 24. The motor shaft 23 is rotatable about the motor axis J1. The motor shaft 23 is generally cylindrical, extending axially about the motor axis J1. The motor shaft 23 is hollow and has openings on both sides in the axial direction. The motor shaft 23 is disposed within the first housing portion 11a. The motor shaft 23 includes a main body 23a and an eccentric shaft portion 23d.

[0030] The main body 23a is the upper part of the motor shaft 23. The main body 23a has a first main body 23b and a second main body 23c. The first main body 23b and the second main body 23c are roughly cylindrical with the motor axis J1 as the center. The second main body 23c is located on the upper side of the first main body 23b. The second main body 23c is connected to the first main body 23b in the axial direction. The inner diameter of the second main body 23c is the same size as the inner diameter of the first main body 23b. The outer diameter of the second main body 23c is smaller than the outer diameter of the first main body 23b. A second bearing 62 is retained on the outer peripheral surface of the second main body 23c. In this embodiment, the second bearing 62 is, for example, a ball bearing.

[0031] The eccentric shaft portion 23d is the lower portion of the motor shaft 23. The eccentric shaft portion 23d is connected to the main body portion 23a in the axial direction. The eccentric shaft portion 23d is arranged inside the first housing portion 11a. The eccentric shaft portion 23d is arranged at a position lower than the rotor 24. A first bearing 61 is retained on the inner circumferential surface of the eccentric shaft portion 23d. In the present embodiment, the first bearing 61 is, for example, a roller bearing. When viewed in the axial direction, the outer circumferential surface of the eccentric shaft portion 23d is a circular shape centered on an eccentric axis J2 that is eccentric relative to the motor axis J1. The eccentric axis J2 is an imaginary axis extending in a direction parallel to the motor axis J1. A fifth bearing 53 is retained on the outer circumferential surface of the eccentric shaft portion 23d. In the present embodiment, the fifth bearing 53 is, for example, a ball bearing.

[0032] The rotor 24 is housed within the first housing portion 11a. The rotor 24 includes a rotor core 24a and rotor magnets 24b. The rotor core 24a is annular, centered on the motor axis J1. The rotor core 24a is fixed to the outer circumference of the first main body 23b. This secures the rotor 24 to the outer circumference of the motor shaft 23. The rotor magnets 24b are fixed to the rotor core 24a.

[0033] The stator 22 and the rotor 24 are radially opposed with a gap therebetween. The stator 22 is positioned radially outside the rotor 24 and housed within the first housing portion 11a. The stator 22 includes an annular stator core 22a that radially surrounds the rotor 24; an insulator 22b mounted on the stator core 22a; and a plurality of coils 22c mounted on the stator core 22a via the insulators 22b. The outer circumference of the stator core 22a is fixed to the inner circumference of the peripheral wall portion 11d. This secures the stator 22 to the housing 10.

[0034] The transmission mechanism 30 is housed within the first housing portion 11a. It is positioned below the rotor 24 and stator 22. The transmission mechanism 30 is coupled to the eccentric shaft portion 23d via the fifth bearing 53. The transmission mechanism 30 is coupled to the output shaft 46. In this embodiment, the transmission mechanism 30 is a speed reduction mechanism that reduces the rotation of the motor shaft 23 and transmits it to the output shaft 46. The transmission mechanism 30 includes an externally toothed gear 31, an internally toothed gear 32, a flange portion 42, and a plurality of protrusions 43.

[0035] The external gear 31 is a generally annular shape extending in a direction perpendicular to the axial direction with the eccentric axis J2 as the center. The inner peripheral surface of the external gear 31 is fixed to the outer peripheral surface of the fifth bearing 53. Thus, the external gear 31 is connected to the eccentric shaft portion 23d of the motor shaft 23 via the fifth bearing 53. The external gear 31 can rotate relative to the motor shaft 23 around the eccentric axis J2. Figure 2 As shown, an external gear portion 31 c including a plurality of external tooth portions 31 d is provided on the outer peripheral surface of the external gear 31 .

[0036] like Figure 1 As shown, the external gear 31 has a plurality of holes 31b that are recessed upward from the lower surface of the external gear 31. In this embodiment, the holes 31b are circular holes that penetrate the external gear 31 in the axial direction. Figure 2 As shown, the holes 31b are arranged around the motor axis J1. The holes 31b are spaced evenly around the circumference of the eccentric axis J2. In this embodiment, eight holes 31b are provided. The inner diameter of the hole 31b is larger than the outer diameter of the portion of the protrusion 43 that is inserted into the hole 31b.

[0037] The internal gear 32 is arranged radially outside the external gear 31. The internal gear 32 is substantially annular with the motor axis J1 as the center. The internal gear 32 surrounds the external gear 31 from the radial outside. Figure 1 As shown, the outer peripheral surface of the internal gear 32 is fixed to the inner peripheral surface of the peripheral wall portion 11d. As a result, the internal gear 32 is fixed to the housing 10. Figure 2 As shown, an internal gear portion 32a having a plurality of internal tooth portions 32b is provided on the inner circumferential surface of the internal gear 32. The internal gear portion 32a meshes with the external gear portion 31c. More specifically, a portion of the internal gear portion 32a in the circumferential direction meshes with the external gear portion 31c.

[0038] The flange portion 42 transmits the rotation of the motor shaft 23 to the output shaft 46. Figure 1 As shown, the flange portion 42 is roughly disc-shaped with the motor axis J1 as the center. The flange portion 42 is arranged below the external gear 31. The flange portion 42 and the external gear 31 are axially opposed to each other with a gap therebetween. In this embodiment, the flange portion 42 is axially connected to the output shaft body 41 of the output shaft 46, which will be described later. In this embodiment, the flange portion 42 and the output shaft body 41 are part of the same single component. The flange portion 42 and the output shaft body 41 may also be different components.

[0039] A plurality of protrusions 43 are provided on the flange portion 42. Each protrusion 43 is cylindrical and protrudes upward from the flange portion 42. Figure 2 As shown, the protrusions 43 are arranged around the motor axis J1. The protrusions 43 are spaced evenly around the motor axis J1 along the circumferential direction. In this embodiment, eight protrusions 43 are provided. Each protrusion 43 is inserted from below into a different hole 31b. A portion of the outer circumferential surface of each protrusion 43 contacts a portion of the inner circumferential surface of the hole 31b. Each protrusion 43 supports the external gear 31 via the inner circumferential surface of each hole 31b, allowing it to swing about the motor axis J1.

[0040] The output shaft 46 outputs the driving force of the electric actuator 1. The rotation of the motor shaft 23 is decelerated and transmitted to the output shaft 46 via the transmission mechanism 30. Figure 1 As shown, the output shaft 46 extends axially. The output shaft 46 is rotatable about the motor axis J1. The output shaft 46 axially penetrates the interior of the motor shaft 23. At least a portion of the output shaft 46 is located within the motor shaft 23. The output shaft 46 protrudes axially from the motor shaft 23 in both directions. The output shaft 46 includes an output shaft body 41 and a retaining member 44 fixed to the outer circumferential surface of the output shaft body 41.

[0041] The output shaft body 41 extends in the axial direction and is supported by a third bearing 51 and a fourth bearing 52 so as to be rotatable about the motor axis J1. The output shaft body 41 includes a connecting portion 41a, a first extending portion 41b, and a second extending portion 41c.

[0042] The connecting portion 41a is the lower portion of the output shaft body 41. It is cylindrical and extends axially about the motor axis J1. It is open at the bottom. The upper end of the connecting portion 41a is axially connected to the downward-facing surface of the flange 42. The lower end of the connecting portion 41a is inserted into the hole 11e.

[0043] The driven shaft DS can be inserted from below into the coupling portion 41a. When the splined portion provided on the outer circumference of the driven shaft DS engages with the splined groove provided on the inner circumference of the coupling portion 41a, the coupling portion 41a and the driven shaft DS are connected. This allows the rotation of the motor shaft 23 to be transmitted to the driven shaft DS via the output shaft 46.

[0044] The first extension portion 41b is cylindrical and extends axially about the motor axis J1. The lower end of the first extension portion 41b is axially connected to the upward-facing surface of the flange portion 42. The first extension portion 41b is disposed within the eccentric shaft portion 23d. The first extension portion 41b is supported by a first bearing 61 for rotation about the motor axis J1. The first bearing 61 determines the radial position of the motor shaft 23 relative to the output shaft 46.

[0045] The second extension portion 41c is cylindrical and extends axially about the motor axis J1. The second extension portion 41c is located above the first extension portion 41b and is axially connected to the first extension portion 41b. The second extension portion 41c axially extends through the interior of the main body portion 23a. The upper portion of the second extension portion 41c protrudes upward from the motor shaft 23. The upper end of the second extension portion 41c is supported by the fourth bearing 52 for rotation about the motor axis J1.

[0046] The retaining member 44 is fixed to the outer circumferential surface of the second extension portion 41c above the motor shaft 23. The retaining member 44 includes a cylindrical portion 44a and a second bearing retaining portion 44c. The cylindrical portion 44a is cylindrical and axially open on both sides, centered on the motor axis J1. The cylindrical portion 44a is fixed to the outer circumferential surface of the second extension portion 41c.

[0047] The second bearing retaining portion 44c is cylindrical and open at the bottom, centered on the motor axis J1. The upper end of the second bearing retaining portion 44c is axially connected to the lower end of the cylindrical portion 44a. The second bearing retaining portion 44c is radially spaced apart from the motor shaft 23. A second bearing 62 is retained on the inner circumferential surface of the second bearing retaining portion 44c. The second bearing 62 determines the radial position of the motor shaft 23 relative to the output shaft 46.

[0048] The circuit substrate 80 is in the shape of a plate extending in the radial direction. The plate surface of the circuit substrate 80 faces the axial direction. The circuit substrate 80 is housed within the second housing portion 11b. The circuit substrate 80 is positioned above the rotor 24, i.e., on one axial side. As viewed from the radial direction, the circuit substrate 80 is positioned so as to overlap with the output shaft 46. A substrate hole 80a is provided in the circuit substrate 80, extending through the circuit substrate 80 in the axial direction. The substrate hole 80a is a generally circular hole centered on the motor axis J1. The output shaft 46 passes through the substrate hole 80a in the axial direction. The substrate hole 80a and the cylindrical portion 44a are radially opposed to each other with a gap therebetween.

[0049] The first rotating component 71 is annular in shape, centered about the motor axis J1. The first rotating component 71 is housed within the second housing portion 11b. The first rotating component 71 is positioned above the motor shaft 23, the retaining component 44, and the circuit board 80. The second extension portion 41c axially extends through the interior of the first rotating component 71. The first rotating component 71 is mounted on the outer circumferential surface of the second extension portion 41c. The first rotating component 71 is mounted on a portion of the output shaft 46 that is above the motor shaft 23, i.e., on one axial side. The first rotating component 71 is rotatable about the motor axis J1 together with the output shaft 46. Alternatively, the first rotating component 71 may be mounted on the cylindrical portion 44a. A first gear portion 71a is provided on the radially outer circumferential surface of the first rotating component 71. The first gear portion 71a extends circumferentially throughout a circle. The first gear portion 71a is composed of a plurality of first teeth (not shown) arranged circumferentially.

[0050] The shaft member 73 is cylindrical and extends in the axial direction. In the present embodiment, the shaft member 73 is made of resin. In the axial direction, the shaft member 73 is arranged between the cover body 12a and the circuit substrate 80. The upper portion of the shaft member 73 is retained on the inner circumferential surface of the shaft member retaining portion 12d. Thus, the shaft member 73 is retained on the housing 10. In the present embodiment, the shaft member 73 and the circuit substrate 80 are axially opposed to each other with a gap therebetween. In addition, the lower portion of the shaft member 73 may also pass through a hole that passes through the circuit substrate 80 in the axial direction and be retained on the inner circumferential surface of the hole.

[0051] The second rotating member 72 is annular and surrounds the shaft member 73. The second rotating member 72 is positioned above the circuit board 80, i.e., on one axial side. The second rotating member 72 and the circuit board 80 are axially opposed with a gap therebetween. The second rotating member 72 is positioned radially outward of the motor axis J1 relative to the first rotating member 71. The outer diameter of the second rotating member 72 is larger than that of the first rotating member 71. In this embodiment, the second rotating member 72 is made of resin. A through-hole 72a, a recessed portion 72c, and a second gear portion 72e are provided in the second rotating member 72.

[0052] The through hole 72a is a hole that passes through the center of the second rotating component 72 in the axial direction. When viewed from the axial direction, the through hole 72a is circular. The shaft component 73 passes through the through hole 72a in the axial direction. In the present embodiment, the shaft component 73 is loosely fitted in the through hole 72a. Thus, the shaft component 73 supports the second rotating component 72 so that it can rotate. Therefore, according to the present embodiment, the second rotating component 72 can be supported in a rotatable manner by the shaft component 73, thereby simplifying the structure that supports the second rotating component 72 in a rotatable manner. As a result, an increase in the number of components of the electric actuator 1 can be suppressed. Therefore, an increase in the manufacturing cost and manufacturing man-hours of the electric actuator 1 can be suppressed.

[0053] The recess 72c is a hole recessed from the downwardly facing surface (i.e., the surface facing the other axial side) of the second rotating member 72 toward the upward side (i.e., one axial side). When viewed axially, the recess 72c is circular. When viewed axially, the recess 72c may also have other shapes, such as a square.

[0054] The second gear portion 72e is provided on the outer peripheral surface of the second rotating member 72 in a radial direction centered on the shaft member 73. The second gear portion 72e extends along the outer peripheral surface of the second rotating member 72 within a circle. The second gear portion 72e is composed of a plurality of second tooth portions, not shown, arranged along the outer peripheral surface of the second rotating member 72. The second gear portion 72e meshes with the first gear portion 71a. Thus, the rotation of the output shaft 46 is transmitted to the second rotating member 72 via the first rotating member 71. As described above, the outer diameter of the second rotating member 72 is larger than the outer diameter of the first rotating member 71. Therefore, the number of teeth of the second gear portion 72e is greater than the number of teeth of the first gear portion 71a. Therefore, the rotation of the first rotating member 71, that is, the rotation of the output shaft 46, is reduced in speed and transmitted to the second rotating member 72.

[0055] According to this embodiment, a first gear portion 71a is provided on the radially outer circumferential surface of the first rotating member 71, and a second gear portion 72e is provided on the second rotating member 72 to mesh with the first gear portion 71a. Therefore, the reduced rotation speed of the output shaft 46 can be transmitted to the second rotating member 72 via the simple structure of the first rotating member 71 mounted on the output shaft 46. This simplifies the structure for transmitting the reduced rotation speed of the output shaft 46 to the second rotating member 72. Consequently, an increase in the number of components of the electric actuator 1 can be more effectively suppressed. Consequently, an increase in the manufacturing cost and number of steps for the electric actuator 1 can be more effectively suppressed.

[0056] The magnet 45 is annular and surrounds the shaft member 73. When viewed from the axial direction, the magnet 45 may also be a square or other shape. In this embodiment, the upper portion of the magnet 45 is arranged inside the recess 72c. When viewed from the radial direction, the magnet 45 is arranged at a position overlapping with the output shaft 46. The upper portion of the magnet 45 is fixed to the inner side surface of the recess 72c. That is, at least a portion of the magnet 45 is fixed to the inner side surface of the recess 72c. Thus, the magnet 45 is fixed to the second rotating member 72. The magnet 45 is fixed to the second rotating member 72 by, for example, an adhesive. Alternatively, the magnet 45 may be arranged as a whole inside the recess 72c. Alternatively, the second rotating member 72 may be formed by insert molding in which the magnet 45 is an embedded member. In this case, at least a portion of the magnet 45 is embedded inside the second rotating member 72. A through hole 45a is provided in the magnet 45.

[0057] The insertion hole 45a is a hole that axially passes through the center of the magnet 45. The shaft member 73 axially passes through the insertion hole 45a. The hole diameter of the insertion hole 45a is sufficiently larger than the diameter of the shaft member 73.

[0058] The magnetic sensor 81 detects the magnetic flux of the magnet 45. The magnetic sensor 81 is mounted on the surface facing the upper side of the circuit substrate 80, that is, on one axial side. When viewed from the radial direction, the magnetic sensor 81 is arranged at a position overlapping with the output shaft 46. In this embodiment, the magnetic sensor 81 is a Hall element such as a Hall IC. The magnetic sensor 81 and the magnet 45 are arranged opposite each other in the axial direction. The magnetic sensor 81 detects the rotation of the second rotating component 72 by detecting the magnetic flux of the magnet 45. As described above, the rotation of the output shaft 46 is decelerated and transmitted to the second rotating component 72. Therefore, the magnetic sensor 81 detects the magnetic flux of the magnet 45 fixed to the second rotating component 72, wherein the rotation of the output shaft 46 is decelerated and transmitted to the second rotating component 72. Therefore, the magnetic sensor 81 can detect the phase of the output shaft 46 at a rotation angle of more than 360°.

[0059] In the shaft component 73, a groove portion (not shown) is provided on the outer peripheral surface of the portion located below the second rotating component 72 and the magnet 45. An anti-slip component 75 is fixed in the groove portion. That is, the anti-slip component 75 is fixed to the portion of the shaft component 73 that is axially closer to the other side than the second rotating component 72 and the magnet 45. In the present embodiment, the anti-slip component 75 is, for example, an E-type retaining ring. The anti-slip component 75 may also be other components such as a C-type retaining ring. In addition, in the case where the shaft component 73 is provided with a hole that passes through in a direction perpendicular to the axial direction, the anti-slip component 75 may also be a pin that passes through the hole. The outer diameter of the anti-slip component 75 is larger than the inner diameter of the through hole 72a and the inner diameter of the insertion hole 45a. In the present embodiment, the anti-slip component 75 is in axial contact with the surface of the magnet 45 facing downward. The anti-slip component 75 may also not be in contact with the magnet 45. The anti-slip member 75 prevents the second rotating member 72 and the magnet 45 from detaching from the shaft member 73 by restricting the second rotating member 72 and the magnet 45 from moving downward. Furthermore, although not shown, the shaft member 73 may also include a structure (e.g., a stepped shape) that restricts the second rotating member 72 and the magnet 45 from moving upward. In this case, since the second rotating member 72 and the magnet 45 can be restricted from moving in both axial directions, the first gear portion 71a and the second gear portion 72e can be more stably engaged.

[0060] According to this embodiment, the electric actuator 1 includes a circuit board 80 positioned above the rotor 24, i.e., on one axial side; a first rotating member 71 attached to a portion of the output shaft 46 above the motor shaft 23; and a second rotating member 72 to which the rotation of the first rotating member 71 is transmitted at reduced speed. The second rotating member 72 is positioned above the circuit board 80, and the magnet 45 is fixed to the second rotating member 72. A magnetic sensor 81 is mounted on the upward-facing surface of the circuit board 80. This magnetic sensor 81 is axially opposed to the magnet 45 and detects the magnetic flux of the magnet 45. Therefore, the magnet 45, magnetic sensor 81, and circuit board 80 can each be positioned so as to overlap with the output shaft 46 when viewed radially. Consequently, the electric actuator 1 can be less enlarged in the axial direction than when the magnet 45, magnetic sensor 81, and circuit board 80 are each positioned above the output shaft 46.

[0061] In a configuration where the magnetic sensor 81 detects the magnetic flux of the magnet 45 directly fixed to the output shaft 46, in order to detect the phase of the output shaft 46 over a rotational angle of 360° or greater, the rotational speed of the output shaft 46 detected by a pulse sensor or the like must be stored in a memory or the like. In this case, if the power supply to the electric actuator 1 is momentarily interrupted, for example, the rotational speed of the output shaft 46 stored in the memory or the like is lost, potentially making the phase of the output shaft 46 unclear. In contrast, in this embodiment, as described above, the magnetic sensor 81 detects the magnetic flux of the magnet 45 fixed to the second rotating member 72, where the rotation of the output shaft 46 is transmitted to the second rotating member 72 at a reduced speed. Therefore, there is no need to store the rotational speed of the output shaft 46 in a memory or the like, and the magnetic sensor 81 can detect the phase of the output shaft 46 over a rotational angle of 360° or greater. Thus, in the electric actuator 1 of this embodiment, the phase of the output shaft 46 can be detected over a rotational angle of 360° or greater, even in the event of a momentary power outage or the like. Therefore, it is possible to suppress an increase in the size of the electric actuator 1 in the axial direction and stably detect the phase of the output shaft 46 at a rotation angle of 360° or more.

[0062] According to this embodiment, the second rotating member 72 is provided with a recessed portion 72c that is recessed from the surface facing downward, i.e., the other axial side, toward the upper side, i.e., the one axial side. At least a portion of the magnet 45 is fixed to the inner side of the recessed portion 72c. This allows at least a portion of the second rotating member 72 to be positioned so as to overlap with the magnet 45 when viewed radially. This makes it easier to position the second rotating member 72 downward, compared to a configuration in which the magnet 45 is mounted on the downward surface of the second rotating member 72, i.e., a configuration in which the second rotating member 72 is positioned so as not to overlap with the magnet 45 when viewed radially. Consequently, the electric actuator 1 can be more appropriately prevented from increasing in size in the axial direction.

[0063] According to this embodiment, a retaining member 75 is fixed to the portion of the shaft member 73 below the second rotating member 72 and the magnet 45, i.e., on the other axial side. The outer diameter of the retaining member 75 is larger than the inner diameters of the through-hole 72a and the insertion hole 45a. Therefore, the retaining member 75 prevents the second rotating member 72 from falling downward from the shaft member 73 and accurately determines the axial position of the second rotating member 72 relative to the first rotating member 71. This ensures stable meshing between the first gear portion 71a and the second gear portion 72e, allowing the rotation of the output shaft 46 to be stably transmitted to the second rotating member 72 via the first rotating member 71. Consequently, the phase of the output shaft 46 can be detected with high precision by the magnetic sensor 81, thereby improving the stability of the operation of the electric actuator 1.

[0064] Furthermore, in this embodiment, as described above, the retaining member 75 is in axial contact with the downwardly facing surface of the magnet 45. Therefore, the retaining member 75 allows the axial position of the magnet 45 relative to the magnetic sensor 81 to be determined with high precision. Consequently, since the magnetic flux of the magnet 45 can be detected with high precision by the magnetic sensor 81, the operational stability of the electric actuator 1 can be further improved.

[0065] <Second embodiment>

[0066] Figure 3 This is a cross-sectional view of an electric actuator 201 according to this embodiment. In the following description, components identical to those in the first embodiment are designated by the same reference numerals, and their descriptions are omitted. In this embodiment, the second rotating member 72 and the first rotating member 71 are radially opposed with a gap therebetween. The remaining structures of the first and second rotating members 71, 72 are identical to those of the first embodiment. In this embodiment, the electric actuator 201 includes a drive member 277.

[0067] The drive member 277 is an endless timing belt driven by the first rotating member 71. The drive member 277 radially surrounds both the first rotating member 71 and the second rotating member 72. The drive member 277 is wound around both the first rotating member 71 and the second rotating member 72. When viewed radially, the drive member 277 is positioned so as to overlap the output shaft 46. Although not shown, the inner circumference of the drive member 277 is provided with multiple protrusions that project inward. These protrusions are arranged along the inner circumference of the drive member 277. Parts of these protrusions mesh with the first gear portion 71a of the first rotating member 71. Other parts of these protrusions mesh with the second gear portion 72e of the second rotating member 72. Consequently, when the first rotating member 71 rotates about the motor axis J1 along with the output shaft 46, the second rotating member 72 rotates following the first rotating member 71 via the drive member 277. In other words, the rotation of the first rotating member 71 is transmitted to the second rotating member 72 via the drive member 277. As described above, the second gear portion 72 e has a larger number of teeth than the first gear portion 71 a . Therefore, the rotation of the first rotating member 71 is transmitted to the second rotating member 72 via the driving member 277 at a reduced speed.

[0068] According to this embodiment, the electric actuator 201 includes an annular drive member 277 wrapped around both the first rotating member 71 and the second rotating member 72. The rotation of the first rotating member 71 is transmitted to the second rotating member 72 via the drive member 277. Therefore, even when there is a large dimensional tolerance between the rotation centers of the second rotating member 72 and the first rotating member 71, the rotation of the first rotating member 71 is easily transmitted to the second rotating member 72. As described above, in this embodiment, only the upper end of the shaft member 73 is retained by the housing 10. Therefore, it is difficult to accurately determine the radial position of the lower portion of the shaft member 73 relative to the motor axis J1. Consequently, it is difficult to accurately determine the position of the rotation center of the second rotating member 72 relative to the motor axis J1, which is the rotation center of the first rotating member 71. Therefore, in a configuration where the rotation of the first rotating member 71 is transmitted to the second rotating member by bringing the first and second rotating members 71 into contact with each other, there is a risk that the rotation of the first rotating member 71 will not be stably transmitted to the second rotating member 72. In contrast, in this embodiment, even if there is a large dimensional tolerance between the rotation center of the second rotating member 72 and the rotation center of the first rotating member 71, the dimensional error can be absorbed by the elastic deformation or deflection of the driving member 277, so that the rotation of the first rotating member 71 can be stably transmitted to the second rotating member 72. Therefore, the structure of the retaining shaft member 73 can be simplified, thereby suppressing an increase in the number of components and manufacturing costs of the electric actuator 201.

[0069] Furthermore, in this embodiment, the magnet 45, the magnetic sensor 81, the circuit board 80, and the drive member 277 can be arranged at positions overlapping the output shaft 46 when viewed in the radial direction. Therefore, compared to a case where the magnet 45, the magnetic sensor 81, the circuit board 80, and the drive member 277 are arranged above the output shaft 46, it is possible to suppress an increase in the size of the electric actuator 201 in the axial direction.

[0070] The above describes the embodiments of the present invention, but the various structures and their combinations in the embodiments are examples, and additions, omissions, substitutions, and other changes to the structures can be made without departing from the scope of the purpose of the present invention. In addition, the present invention is not limited to the embodiments.

[0071] The second rotating member may not be provided with a recessed portion. In this case, it is preferred that the magnet be fixed to the downwardly directed surface of the second rotating member.

[0072] The shaft member may be rotatably supported on the housing. In this case, the second rotating member may be fixed to the shaft member or may be rotatably supported by the shaft member.

[0073] The structure of the transmission mechanism is not particularly limited as long as it can transmit the rotation of the motor shaft to the output shaft. The transmission mechanism can be a speed-increasing mechanism or a mechanism that does not change the speed of the rotation of the motor shaft. In addition, the multiple protrusions and the flange portion can also be independent of each other. In this case, each of the multiple protrusions is fixed to each of the multiple holes that pass through the flange portion. In addition, multiple protrusions can be provided on the external gear and multiple holes can be provided on the flange portion. In this case, each of the multiple protrusions protrudes from the external gear toward the flange portion and is inserted into the hole portion of the flange portion. In addition, the number of holes and the number of protrusions can be less than 7 or more than 9, respectively.

[0074] The application of the electric actuator of the present invention is not particularly limited. The electric actuator can be mounted on a shift-by-wire actuator device that is driven based on a driver's shift operation. Furthermore, the electric actuator can be mounted on equipment other than vehicles. Note that the above-described structures described in this specification may be combined as appropriate within the scope of non-inconsistency.

[0075] Note that the present invention can adopt the following structures.

[0076] (1) An electric actuator comprising: a motor having a hollow motor shaft rotatable about a motor axis and a rotor fixed to the outer peripheral surface of the motor shaft; a transmission mechanism connected to the motor shaft; an output shaft extending in the axial direction and to which the rotation of the motor shaft is transmitted via the transmission mechanism; a circuit substrate arranged on an axial side of the rotor; a first rotating member mounted on a portion of the output shaft on an axial side of the motor shaft; and a second rotating member to which the rotation of the first rotating member is reduced in speed, at least a portion of the output shaft being located inside the motor shaft, the second rotating member being arranged on an axial side of the circuit substrate, a magnet being fixed to the second rotating member, and a magnetic sensor being mounted on a surface of the circuit substrate facing the axial side, the magnetic sensor being arranged axially opposite to the magnet and detecting the magnetic flux of the magnet.

[0077] (2) The electric actuator according to (1), wherein a first gear portion is provided on a radially outer peripheral surface of the first rotating member, and a second gear portion meshing with the first gear portion is provided on the second rotating member.

[0078] (3) The electric actuator according to (1), further comprising an annular driving member that is wound around both the first rotating member and the second rotating member, wherein the rotation of the first rotating member is transmitted to the second rotating member via the driving member.

[0079] (4) An electric actuator according to any one of (1) to (3), wherein the second rotating member is provided with a recessed portion that is recessed from a surface facing the other axial side toward one axial side, and at least a portion of the magnet is fixed to an inner surface of the recessed portion.

[0080] (5) An electric actuator according to any one of (1) to (4), comprising: a housing which accommodates the motor, the transmission mechanism and the output shaft; and a shaft member which is retained in the housing and extends axially, wherein a through hole which axially penetrates the second rotating member is provided in the second rotating member, and the shaft member axially penetrates the through hole and supports the second rotating member so as to be rotatable.

[0081] (6) An electric actuator according to (5), wherein a through hole is provided in the magnet and passes through the magnet in the axial direction, the shaft member passes through the through hole in the axial direction, and an anti-slip component is fixed to a portion of the shaft member that is closer to the other axial side than the second rotating member and the magnet, and the outer diameter of the anti-slip component is larger than the inner diameter of the through hole and the inner diameter of the through hole.

[0082] Explanation of symbols

[0083] 1. 201—electric actuator; 10—housing; 20—motor; 23—motor shaft; 24—rotor; 30—transmission mechanism; 45—magnet; 46—output shaft; 71—first rotating member; 71a—first gear portion; 72—second rotating member; 72a—through hole; 72c—recess; 72e—second gear portion; 73—shaft member; 75—anti-slip member; 80—circuit board; 81—magnetic sensor; 277—drive member; J1—motor axis.

Claims

1. An electric actuator, characterized in that: have: a motor having a hollow motor shaft rotatable about a motor axis, and a rotor fixed to an outer peripheral surface of the motor shaft; a transmission mechanism connected to the motor shaft; an output shaft extending in the axial direction, to which the rotation of the motor shaft is transmitted via the transmission mechanism; a circuit substrate disposed on one axial side of the rotor; a first rotating member mounted on a portion of the output shaft that is axially closer to one side than the motor shaft; as well as a second rotating member to which the rotation of the first rotating member is transmitted at a reduced speed; At least a portion of the output shaft is located inside the motor shaft. The second rotating member is arranged on one side of the circuit substrate in the axial direction. A magnet is fixed to the second rotating member. A magnetic sensor is mounted on a surface of the circuit board facing one axial side. The magnetic sensor is arranged to face the magnet in the axial direction and detects magnetic flux of the magnet.

2. The electric actuator according to claim 1, wherein: A first gear portion is provided on the radial outer peripheral surface of the first rotating member. The second rotating member is provided with a second gear portion that meshes with the first gear portion.

3. The electric actuator according to claim 1, wherein: An annular driving member is provided, the driving member being wound around both the first rotating member and the second rotating member. The rotation of the first rotating member is transmitted to the second rotating member via the driving member.

4. The electric actuator according to claim 1, wherein: The second rotating member is provided with a recessed portion that is recessed from a surface facing the other axial side toward one axial side. At least a portion of the magnet is fixed to the inner side surface of the recess.

5. The electric actuator according to any one of claims 1 to 4, characterized in that: have: a housing that houses the motor, the transmission mechanism, and the output shaft; and a shaft member held in the housing and extending in the axial direction; The second rotating member is provided with a through hole that penetrates the second rotating member in the axial direction. The shaft member passes through the through hole in the axial direction and rotatably supports the second rotating member.

6. The electric actuator according to claim 5, wherein: The magnet is provided with an insertion hole that penetrates the magnet in the axial direction. The shaft member passes through the insertion hole in the axial direction. A retaining member is fixed to a portion of the shaft member that is closer to the other side in the axial direction than the second rotating member and the magnet. The outer diameter of the anti-drop member is larger than the inner diameter of the through hole and the inner diameter of the insertion hole.

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