JP2022056524A - Electric actuator - Google Patents

Abstract

To provide an electric actuator having a structure which can prevent a motor shaft and an output shaft from inclining to each other.SOLUTION: An electric actuator 100 comprises: a motor 20 which has a motor shaft 21a rotatable around a motor axis; a transmission mechanism 30 which is coupled to one side in the axial direction of the motor shaft; and an output shaft 41 which extends in the axial direction of the motor shaft, and to which rotation of the motor shaft is transmitted via the transmission mechanism. The motor shaft is a hollow shaft. At least part of the output shaft is located inside the motor shaft. One of the motor shaft and the output shaft rotatably supports the other one of the motor shaft and the output shaft.SELECTED DRAWING: Figure 1

Description

The present invention relates to an electric actuator.

An electric actuator including a motor shaft and an output shaft connected by a transmission mechanism is known. For example, Patent Document 1 describes a rotary actuator applied as a power source of a shift-by-wire system for switching a shift of an automatic transmission of a vehicle.

Japanese Unexamined Patent Publication No. 2016-109226

In the electric actuator as described above, one of the motor shaft and the output shaft may be tilted with respect to the other.

In view of the above circumstances, it is one of the objects of the present invention to provide an electric actuator having a structure capable of suppressing the motor shaft and the output shaft from tilting each other.

One aspect of the electric actuator of the present invention is a motor having a motor shaft rotatable about a motor shaft, a transmission mechanism connected to one side of the motor shaft in the axial direction, and extending in the axial direction of the motor shaft. , An output shaft in which the rotation of the motor shaft is transmitted via the transmission mechanism. The motor shaft is a hollow shaft. At least a portion of the output shaft is located inside the motor shaft. One of the motor shaft and the output shaft rotatably supports the other of the motor shaft and the output shaft.

According to one aspect of the present invention, in the electric actuator, it is possible to prevent the motor shaft and the output shaft from tilting with each other.

FIG. 1 is a cross-sectional view showing an electric actuator of the present embodiment. FIG. 2 is a diagram showing a transmission mechanism of the present embodiment, and is a cross-sectional view taken along the line II-II in FIG.

In each figure, the Z-axis direction is a vertical direction in which the positive side (+ Z side) is the upper side and the negative side (-Z side) is the lower side. The axial direction of the motor shaft J1 shown in each figure is parallel to the Z-axis direction, that is, the vertical direction. In the following description, the direction parallel to the axial direction of the motor shaft J1 is simply referred to as "axial direction". Further, the radial direction centered on the motor shaft J1 is simply referred to as "diametrical direction", and the circumferential direction centered on the motor shaft J1 is simply referred to as "circumferential direction".

In this embodiment, the lower side corresponds to "one side in the axial direction" and the upper side corresponds to "the other side in the axial direction". The vertical direction, the upper side, and the lower side are simply names for explaining the relative positional relationship of each part, and the actual arrangement relationship, etc. is an arrangement relationship other than the arrangement relationship, etc. indicated by these names. There may be.

The electric actuator 100 of the present embodiment shown in FIG. 1 is attached to a vehicle. More specifically, the electric actuator 100 is mounted on, for example, a park-by-wire actuator device driven based on a shift operation of the driver of the vehicle. As shown in FIG. 1, the electric actuator 100 includes a case 10, a motor 20, a transmission mechanism 30, an output unit 40, a first bearing 51, a second bearing 52, a third bearing 53, and a washer 61. , 62, the bus bar unit 70, the substrate 80, the first rotation sensor 81, the second rotation sensor 82, the first detected portion 24, the mounting member 44, the second detected portion 45, and the partition member. 90 and. The first bearing 51, the second bearing 52, and the third bearing 53 are, for example, ball bearings.

The case 10 houses each part of the electric actuator 100 including the motor 20 and the transmission mechanism 30 inside. The case 10 has a case main body 11, a cover 12, and an inner lid 13. The case body 11 is open on the upper side. The case body 11 has, for example, a cylindrical shape centered on the motor shaft J1. The case body 11 has a first accommodating portion 11a and a second accommodating portion 11b.

The first accommodating portion 11a is, for example, a lower portion of the case body 11. The first accommodating portion 11a has a bottom portion 11c located on the lower side and a tubular portion 11d extending upward from the radial outer edge portion of the bottom portion 11c. The bottom portion 11c has a hole portion 11e that penetrates the bottom portion 11c in the axial direction. The hole portion 11e is, for example, a circular hole centered on the motor shaft J1. The upper portion of the hole portion 11e constitutes a first bearing holding portion 11f that holds the first bearing 51 inside. The first bearing 51 is held in the case main body 11 by being held inside the first bearing holding portion 11f. The outer ring of the first bearing 51 is fitted, for example, to the inner peripheral surface of the first bearing holding portion 11f.

The second accommodating portion 11b is, for example, an upper portion of the case body 11. The second accommodating portion 11b is connected to the upper side of the first accommodating portion 11a. The second accommodating portion 11b has a tubular shape that opens upward. The inner diameter of the second accommodating portion 11b is larger than the inner diameter of the first accommodating portion 11a. The outer diameter of the second accommodating portion 11b is larger than the outer diameter of the first accommodating portion 11a. The lower end portion of the second accommodating portion 11b is connected to, for example, the radial outer edge portion of the upper end portion of the tubular portion 11d. The inner peripheral surface of the second accommodating portion 11b is provided with a step having a stepped surface 11g facing upward. The stepped surface 11g is, for example, a surface orthogonal to the axial direction.

The substrate 80 is fixed to the stepped surface 11g. The substrate 80 has a plate shape in which the plate surface faces the axial direction, and extends in the radial direction. The radial outer edge portion of the substrate 80 is fixed to, for example, the stepped surface 11g with screws. The substrate 80 is housed inside the second housing section 11b. The substrate 80 is located above the rotor body 21b, which will be described later. The substrate 80 has a through hole 80a that penetrates the substrate 80 in the axial direction. The through hole 80a is, for example, a circular hole centered on the motor shaft J1. The upper portion of the output shaft 41, which will be described later, is passed through the through hole 80a in the axial direction. Printed wiring (not shown) is provided on the surface of the substrate 80. Although not shown, the substrate 80 is provided with, for example, an inverter circuit that supplies electric power to the motor 20.

The first rotation sensor 81 and the second rotation sensor 82 are attached to the substrate 80. The first rotation sensor 81 is a sensor capable of detecting the rotation of the motor shaft 21a, which will be described later. The second rotation sensor 82 is a sensor capable of detecting the rotation of the output shaft 41, which will be described later. In the present embodiment, the first rotation sensor 81 and the second rotation sensor 82 are magnetic sensors. The first rotation sensor 81 and the second rotation sensor 82 are Hall elements such as Hall ICs. A plurality of the first rotation sensor 81 and the second rotation sensor 82 may be provided, for example, along the circumferential direction.

In the present embodiment, the first rotation sensor 81 is attached to the lower surface of the substrate 80. The first rotation sensor 81 is attached to, for example, the peripheral portion of the through hole 80a on the lower surface of the substrate 80. In the present embodiment, the second rotation sensor 82 is attached to the upper surface of the substrate 80. The second rotation sensor 82 is located, for example, radially outside the first rotation sensor 81. That is, in the present embodiment, the first rotation sensor 81 and the second rotation sensor 82 have different radial positions from each other.

The cover 12 is fixed to the case body 11. The radial outer edge of the cover 12 is, for example, screwed to the upper end of the second accommodating portion 11b. The cover 12 closes the upper opening of the case body 11. The cover 12 has a cover main body 12a that covers the upper opening of the case main body 11 and a second bearing holding portion 12b that projects downward from the cover main body 12a. The second bearing holding portion 12b has, for example, a cylindrical shape that opens downward with the motor shaft J1 as the center. The second bearing 52 is held inside the second bearing holding portion 12b. As a result, the second bearing 52 is held by the cover 12. The outer ring of the second bearing 52 is fitted, for example, to the inner peripheral surface of the second bearing holding portion 12b.

The inner lid 13 is located inside the case body 11. The inner lid 13 has, for example, a plate shape in which the plate surface faces the axial direction. The inner lid 13 has, for example, a disk shape centered on the motor shaft J1. The inner lid 13 axially partitions the inside of the first accommodating portion 11a and the inside of the second accommodating portion 11b. The radial outer edge portion of the inner lid 13 is fixed to, for example, the upper end portion of the first accommodating portion 11a with a screw. The inner lid 13 has holes 13a and 13b that penetrate the inner lid 13 in the axial direction. The hole portion 13a is, for example, a circular hole centered on the motor shaft J1. The hole portion 13b overlaps with the stator 22 described later when viewed in the axial direction.

A bus bar unit 70 is arranged on the upper surface of the inner lid 13. The bus bar unit 70 has a bus bar holder 71 and a bus bar 72. The bus bar holder 71 is a resin member that holds the bus bar 72. The bus bar 72 electrically connects the leader wire 22d drawn from the coil 22c of the stator 22 described later to the substrate 80. For example, a plurality of bus bars 72 are provided. The inverter circuit provided on the substrate 80 supplies electric power to the stator 22 via the bus bar 72.

The motor 20 has a rotor 21 and a stator 22. The rotor 21 has a motor shaft 21a and a rotor main body 21b. That is, the motor 20 has a motor shaft 21a and a rotor main body 21b. The motor shaft 21a is rotatable about the motor shaft J1. The motor shaft 21a is a hollow shaft. The motor shaft 21a has, for example, a cylindrical shape extending in the axial direction about the motor shaft J1. The motor shaft 21a is open on both sides in the axial direction. The inner diameter of the motor shaft 21a is, for example, uniform over the entire axial direction. The motor shaft 21a extends upward from the inside of the first accommodating portion 11a and protrudes into the inside of the second accommodating portion 11b through the hole portion 13a. The motor shaft 21a has a main body portion 21c, an eccentric shaft portion 21d, and a fixed portion 21e.

The main body portion 21c is a portion to which the rotor main body 21b is fixed. The upper end of the main body 21c is passed through, for example, the hole 13a of the inner lid 13. The portion of the main body portion 21c excluding the upper end is located inside the first accommodating portion 11a.

The eccentric shaft portion 21d is connected to the lower side of the main body portion 21c. The eccentric shaft portion 21d is located inside the first accommodating portion 11a. The lower end of the eccentric shaft portion 21d is, for example, the lower end of the motor shaft 21a. The eccentric shaft portion 21d is a portion centered on the eccentric shaft J2 that is eccentric with respect to the motor shaft J1. The eccentric shaft J2 is parallel to the motor shaft J1. The inner ring of the third bearing 53 is fitted and fixed to the eccentric shaft portion 21d. As a result, the third bearing 53 is fixed to the motor shaft 21a.

The fixed portion 21e is connected to the upper side of the main body portion 21c. The fixed portion 21e is located inside, for example, the second accommodating portion 11b. The fixed portion 21e is located above the rotor main body 21b. The upper end of the fixed portion 21e is, for example, the upper end of the motor shaft 21a. The upper end of the fixed portion 21e is located, for example, in the through hole 80a of the substrate 80. The outer diameter of the fixed portion 21e is smaller than the outer diameter of the main body portion 21c. A step having a stepped surface 21f facing upward is provided between the outer peripheral surface of the fixed portion 21e and the outer peripheral surface of the main body portion 21c in the axial direction. The step surface 21f is, for example, orthogonal to the axial direction. The step surface 21f is an upper end surface of the main body portion 21c. The stepped surface 21f is located, for example, above the upper surface of the inner lid 13.

The first detected portion 24 is fixed to the fixed portion 21e. As a result, the first detected portion 24 is provided on the portion of the motor shaft 21a located above the rotor main body 21b. The first detected unit 24 is a portion where rotation is detected by the first rotation sensor 81. In the present embodiment, the first detected unit 24 is a magnet. That is, in the present embodiment, the first rotation sensor 81 detects the rotation of the first detected unit 24 by detecting the magnetic field of the first detected unit 24, and the motor shaft to which the first detected unit 24 is fixed is fixed. The rotation of 21a is detected. The first detected portion 24 is, for example, an annular shape centered on the motor shaft J1. The inner peripheral surface of the first detected portion 24 is fixed to the outer peripheral surface of the fixed portion 21e. The lower surface of the first detected portion 24 is in contact with the stepped surface 21f.

The first detected portion 24 protrudes radially outward from the main body portion 21c. The outer diameter of the first detected portion 24 is, for example, larger than the inner diameter of the hole portion 13a. The radial outer edge portion of the first detected portion 24 is located above the inner lid 13 and is located radially outside the inner edge of the hole portion 13a. The first detected portion 24 is located below the substrate 80. The radial outer edge portion of the first detected portion 24 is arranged so as to face the lower side of the first rotation sensor 81. In the present embodiment, the first rotation sensor 81 and the first detected portion 24 overlap each other when viewed in the axial direction.

The rotor body 21b is fixed to the outer peripheral surface of the motor shaft 21a. The rotor main body 21b is fixed to, for example, an axial center portion on the outer peripheral surface of the main body portion 21c. The rotor main body 21b is housed inside the first housing portion 11a. Although not shown, the rotor body 21b has a cylindrical rotor core fixed to the outer peripheral surface of the motor shaft 21a and a rotor magnet fixed to the rotor core.

The stator 22 faces the rotor 21 in the radial direction via a gap. The stator 22 is located radially outside the rotor 21. The stator 22 is housed inside the first housing portion 11a. The stator 22 has an annular stator core 22a that surrounds the radially outer side of the rotor body 21b, an insulator 22b mounted on the stator core 22a, and a plurality of coils 22c mounted on the stator core 22a via the insulator 22b. The outer peripheral surface of the stator core 22a is fixed to, for example, the inner peripheral surface of the tubular portion 11d. A leader wire 22d is drawn upward from the coil 22c. The leader line 22d penetrates the hole 13b in the axial direction and is connected to the bus bar 72.

The transmission mechanism 30 is located below the rotor body 21b and the stator 22 inside the first accommodating portion 11a. In the present embodiment, the transmission mechanism 30 is a deceleration mechanism that decelerates the rotation of the motor shaft 21a and transmits the rotation to the output shaft 41. The transmission mechanism 30 has an external tooth gear 31, an internal tooth gear 32, an output flange portion 42, and a plurality of protruding portions 43.

The external tooth gear 31 has a substantially annular plate shape extending in a plane orthogonal to the axial direction with the eccentric axis J2 of the eccentric axis portion 21d as the center. As shown in FIG. 2, a gear portion composed of a plurality of tooth portions 31a is provided on the radial outer surface of the external tooth gear 31. The external tooth gear 31 is connected to the eccentric shaft portion 21d via a third bearing 53. As a result, the transmission mechanism 30 is connected to the lower side of the motor shaft 21a. In this embodiment, the transmission mechanism 30 is connected to the lower end of the motor shaft 21a. The external tooth gear 31 is fitted to the outer ring of the third bearing 53 from the outside in the radial direction. As a result, the third bearing 53 connects the motor shaft 21a and the external tooth gear 31 so as to be relatively rotatable around the eccentric shaft J2.

The external tooth gear 31 has a plurality of holes 31b recessed upward from the lower surface of the external tooth gear 31. In the present embodiment, the hole portion 31b penetrates the external tooth gear 31 in the axial direction. The plurality of hole portions 31b are arranged so as to surround the motor shaft J1. More specifically, the plurality of hole portions 31b are arranged at equal intervals over one circumference along the circumferential direction centered on the eccentric axis J2. For example, eight holes 31b are provided. The shape seen along the axial direction of the hole portion 31b is, for example, a circular shape. The inner diameter of the hole 31b is larger than the outer diameter of the portion of the protrusion 43 described later that is inserted into the hole 31b.

The internal tooth gear 32 surrounds the radial outer side of the external tooth gear 31 and meshes with the external tooth gear 31. The internal tooth gear 32 is an annular shape centered on the motor shaft J1. As shown in FIG. 1, in this embodiment, the internal tooth gear 32 is fixed to the case 10. The outer peripheral surface of the internal tooth gear 32 is fitted and fixed to the inner peripheral surface of the first accommodating portion 11a. As shown in FIG. 2, a gear portion having a plurality of tooth portions 32a is provided on the inner peripheral surface of the internal tooth gear 32. The gear portion of the internal tooth gear 32 meshes with the gear portion of the external tooth gear 31. More specifically, the gear portion of the internal tooth gear 32 meshes with the gear portion of the external tooth gear 31 in a part in the circumferential direction.

The output flange portion 42 is a part of the output portion 40. As shown in FIG. 1, the output flange portion 42 is arranged so as to face the lower side of the external tooth gear 31. A gap is provided between the output flange portion 42 and the external tooth gear 31 in the axial direction. The output flange portion 42 has, for example, an annular plate shape that extends in the radial direction about the motor shaft J1. The output flange portion 42 extends radially outward from a portion of the output shaft 41 described later, which is located below the motor shaft 21a. The output flange portion 42 extends radially outward from the upper end portion of the connecting portion 41a, which will be described later, for example.

The output flange portion 42 has a plurality of fixing holes 42a that penetrate the output flange portion 42 in the axial direction. As shown in FIG. 2, the plurality of fixing holes 42a are arranged so as to surround the motor shaft J1. More specifically, the plurality of fixing holes 42a are arranged at equal intervals over one circumference along the circumferential direction centered on the motor shaft J1. For example, eight fixing holes 42a are provided. The shape seen along the axial direction of the fixing hole 42a is a circular shape.

As shown in FIG. 1, in the present embodiment, the protrusion 43 is a columnar member extending in the axial direction. The lower portion of each protrusion 43 is fixed, for example, in each fixing hole 42a. The upper portion of each protrusion 43 is located above the fixing hole 42a. As a result, the plurality of projecting portions 43 project axially from the output flange portion 42 toward the external tooth gear 31. As shown in FIG. 2, the plurality of projecting portions 43 are arranged so as to surround the motor shaft J1. The plurality of protrusions 43 are arranged at equal intervals, for example, along the circumferential direction. For example, eight protrusions 43 are provided.

As shown in FIG. 1, the plurality of projecting portions 43 are inserted into each of the plurality of hole portions 31b from below. The outer diameter of the portion of the protruding portion 43 inserted into the hole portion 31b is smaller than the inner diameter of the hole portion 31b. The outer peripheral surface of the protruding portion 43 is inscribed with the inner surface of the hole portion 31b. The plurality of protruding portions 43 support the external tooth gear 31 so as to be swingable around the motor shaft J1 via the inner surface of the hole portion 31b.

The output unit 40 is a portion that outputs the driving force of the electric actuator 100. The rotation of the motor shaft 21a is transmitted to the output unit 40 via the transmission mechanism 30. The output unit 40 has an output shaft 41 and an output flange unit 42. That is, the electric actuator 100 includes an output shaft 41 and an output flange portion 42. The output unit 40 is, for example, a single member.

The output shaft 41 extends in the axial direction of the motor shaft 21a. The output shaft 41 is arranged coaxially with the motor shaft 21a. That is, the output shaft 41 can rotate about the motor shaft J1. The output shaft 41 is rotatably supported by a first bearing 51 and a second bearing 52. The output shaft 41 has a connecting portion 41a and an extending portion 41b.

The connecting portion 41a is located below the motor shaft 21a. The outer diameter of the connecting portion 41a is larger than the outer diameter of the stretched portion 41b. The connecting portion 41a is inserted into, for example, the inside of the hole portion 11e. The lower end of the connecting portion 41a is, for example, the lower end of the output shaft 41. The lower end of the connecting portion 41a is, for example, in the same axial position as the lower end of the hole 11e. The connecting portion 41a is rotatably supported around the motor shaft J1 by the first bearing 51. As a result, the first bearing 51 rotatably supports the portion of the output shaft 41 located below the motor shaft 21a.

The connecting portion 41a has a connecting recess 41c that is recessed upward from the lower end surface of the connecting portion 41a. The connecting recess 41c opens downward and is exposed to the outside of the case 10. The connecting recess 41c has, for example, a circular shape centered on the motor shaft J1 when viewed from below. A spline groove is provided on the inner peripheral surface of the connecting recess 41c. The driven shaft DS is inserted from below into the connecting recess 41c and connected. As a result, the driven shaft DS is connected to the connecting portion 41a. More specifically, the output shaft 41 and the driven shaft DS are formed by fitting the spline portion provided on the outer peripheral surface of the driven shaft DS into the spline groove provided on the inner peripheral surface of the connecting recess 41c. Be concatenated. The driving force of the electric actuator 100 is transmitted to the driven shaft DS via the output shaft 41. As a result, the electric actuator 100 rotates the driven shaft DS around the motor shaft J1.

The stretched portion 41b extends upward from the connecting portion 41a. More specifically, the stretched portion 41b extends upward from a radial center at the upper end of the connecting portion 41a. The stretched portion 41b is, for example, a columnar shape extending in the axial direction about the motor shaft J1. The axial dimension of the stretched portion 41b is, for example, larger than the axial dimension of the connecting portion 41a. The stretched portion 41b is passed through the inside of the motor shaft 21a, which is a hollow shaft. As a result, at least a part of the output shaft 41 is located inside the motor shaft 21a. In the present embodiment, a part of the extension portion 41b of the output shaft 41 is located inside the motor shaft 21a.

The stretched portion 41b is inserted into the inside of the motor shaft 21a from the lower side of the motor shaft 21a and protrudes upward from the motor shaft 21a. As a result, the output shaft 41 extends from the lower side of the motor shaft 21a to the upper side of the motor shaft 21a through the inside of the motor shaft 21a. The stretched portion 41b is axially passed through the hole portion 13a of the inner lid 13 and the through hole 80a of the substrate 80. The portion of the output shaft 41 located above the motor shaft 21a is located inside, for example, the second accommodating portion 11b. The upper end of the stretched portion 41b is rotatably supported around the motor shaft J1 by the second bearing 52. As a result, the second bearing 52 rotatably supports the portion of the output shaft 41 located above the motor shaft 21a.

The outer diameter of the stretched portion 41b is slightly smaller than, for example, the inner diameter of the motor shaft 21a. In the present embodiment, the stretched portion 41b is gap-fitted inside the motor shaft 21a. The radial gap between the stretched portion 41b and the motor shaft 21a is small enough to rotatably support the motor shaft 21a around the motor shaft J1 by the stretched portion 41b. As described above, in the present embodiment, the output shaft 41 rotatably supports the motor shaft 21a by the extending portion 41b. The portion of the output shaft 41 located inside the motor shaft 21a, that is, the outer peripheral surface of a part of the stretched portion 41b and the inner peripheral surface of the motor shaft 21a face each other in the radial direction and are in contact with each other. A part of the inner peripheral surface of the motor shaft 21a comes into contact with the outer peripheral surface of the output shaft 41, so that the motor shaft 21a is supported in the radial direction. For example, lubricating oil may be provided in the radial gap between the output shaft 41 and the motor shaft 21a.

The second detected portion 45 is fixed to the portion of the stretched portion 41b located above the motor shaft 21a. That is, in the present embodiment, the second detected portion 45 is provided in the portion of the output shaft 41 located above the motor shaft 21a. The second detected portion 45 is a portion where rotation is detected by the second rotation sensor 82. In the present embodiment, the second detected portion 45 is a magnet. In the present embodiment, the second rotation sensor 82 detects the rotation of the second detected unit 45 by detecting the magnetic field of the second detected unit 45, and detects the rotation of the output shaft 41.

In the present embodiment, the second detected portion 45 is attached to the output shaft 41 via the attachment member 44. The mounting member 44 has a fixed cylinder portion 44a and a flange portion 44b. The fixed cylinder portion 44a has, for example, a cylindrical shape that opens on both sides in the axial direction with the motor shaft J1 as the center. The fixed cylinder portion 44a is fitted and fixed to the outer peripheral surface of the portion of the stretched portion 41b located above the motor shaft 21a and below the second bearing 52. As a result, the mounting member 44 is fixed to the outer peripheral surface of the portion of the output shaft 41 located above the motor shaft 21a. The fixed cylinder portion 44a is located between the motor shaft 21a and the second bearing 52 in the axial direction. The flange portion 44b extends radially outward from the upper end portion of the fixed cylinder portion 44a. The flange portion 44b is, for example, an annular shape centered on the motor shaft J1. The radial outer edge portion on the lower surface of the flange portion 44b is recessed upward, for example.

The second detected portion 45 is, for example, an annular shape centered on the motor shaft J1. The second detected portion 45 is fixed to the radial outer edge portion on the lower surface of the flange portion 44b. The second detected portion 45 is located on the upper side of the substrate 80. The inner diameter and outer diameter of the second detected portion 45 are larger than the outer diameter of the first detected portion 24. The second detected unit 45 is located radially outside the first detected unit 24. That is, in the present embodiment, the first detected unit 24 and the second detected unit 45 have different radial positions from each other. The radial outer edge portion of the second detected portion 45 is arranged so as to face the upper side of the second rotation sensor 82. In the present embodiment, the second rotation sensor 82 and the second detected portion 45 overlap each other when viewed in the axial direction. The second rotation sensor 82 and the second detected unit 45 do not overlap with the first rotation sensor 81 and the first detected unit 24 when viewed in the axial direction. The second detected portion 45, for example, overlaps with the rotor main body 21b when viewed in the axial direction.

A washer 61 is provided between the lower end of the motor shaft 21a and the upper end of the connecting portion 41a. A washer 62 is provided between the upper end of the motor shaft 21a and the lower end of the mounting member 44. In the present embodiment, the lower end portion of the mounting member 44 is the lower end portion of the fixed cylinder portion 44a. The washer 61 and the washer 62 are, for example, an annular shape centered on the motor shaft J1. The washer 61 and the washer 62 are, for example, in the shape of a plate whose plate surface faces in the axial direction. The washer 61 and the washer 62 are, for example, slip washers.

The washer 61 and the washer 62 surround the stretched portion 41b. The lower surface of the washer 61 is in contact with the peripheral edge of the extended portion 41b of the upper surfaces of the connecting portion 41a. The upper surface of the washer 61 is in contact with the lower end surface of the motor shaft 21a. The lower surface of the washer 62 is in contact with the upper end surface of the motor shaft 21a. The upper surface of the washer 62 is in contact with the lower end surface of the mounting member 44.

The partition member 90 is located between the stator 22 and the transmission mechanism 30 in the axial direction. The partition member 90 surrounds the motor shaft J1. The partition member 90 has a partition member main body 91 and a peripheral wall portion 92. The partition member main body 91 is, for example, an annular shape centered on the motor shaft J1. The partition member main body 91 has a plate shape in which the plate surface faces the axial direction. The radial inner edge portion of the partition member main body 91 is located radially outside the radial inner edge portion of the insulator 22b. The peripheral wall portion 92 projects upward from the radial outer edge portion of the partition member main body 91. The peripheral wall portion 92 has, for example, a cylindrical shape centered on the motor shaft J1. The peripheral wall portion 92 is fitted and fixed to the inner peripheral surface of the first accommodating portion 11a. The upper end of the peripheral wall 92 is in contact with the radial outer edge of the lower end of the stator core 22a.

When power is supplied to the motor 20 and the motor shaft 21a is rotated around the motor shaft J1, the eccentric shaft portion 21d revolves around the motor shaft J1 in the circumferential direction. The revolution of the eccentric shaft portion 21d is transmitted to the external tooth gear 31 via the third bearing 53, and the position of the external tooth gear 31 inscribed between the inner peripheral surface of the hole portion 31b and the outer peripheral surface of the protruding portion 43 changes. While swinging. As a result, the position where the gear portion of the external tooth gear 31 and the gear portion of the internal tooth gear 32 mesh with each other changes in the circumferential direction. Therefore, the rotational force of the motor shaft 21a is transmitted to the internal gear 32 via the external gear 31.

Here, in the present embodiment, the internal tooth gear 32 is fixed to the case 10 and therefore does not rotate. Therefore, the external tooth gear 31 rotates around the eccentric shaft J2 due to the reaction force of the rotational force transmitted to the internal tooth gear 32. At this time, the rotation direction of the external tooth gear 31 is opposite to the rotation direction of the motor shaft 21a. The rotation of the external tooth gear 31 around the eccentric shaft J2 is transmitted to the output flange portion 42 via the hole portion 31b and the protruding portion 43. As a result, the output shaft 41 rotates around the motor shaft J1. In this way, the rotation of the motor shaft 21a is transmitted to the output shaft 41 via the transmission mechanism 30. Since the structure of the transmission mechanism 30 as the deceleration mechanism is such that the rotation is transmitted via the plurality of protrusions 43 as described above, the reduction ratio of the rotation of the output shaft 41 to the rotation of the motor shaft 21a is compared. You can make it bigger. Therefore, the rotational torque of the output shaft 41 can be relatively large.

According to the present embodiment, the motor shaft 21a is a hollow shaft, and at least a part of the output shaft 41 is located inside the motor shaft 21a. The output shaft 41 rotatably supports the motor shaft 21a. Therefore, even if the motor shaft 21a tries to tilt in the radial direction with respect to the output shaft 41, the motor shaft 21a is supported by the output shaft 41. This prevents the motor shaft 21a from tilting with respect to the output shaft 41. Therefore, it is possible to prevent the motor shaft 21a and the output shaft 41 from tilting with each other. Further, since the motor shaft 21a can be supported by the output shaft 41, it is not necessary to separately provide a bearing that rotatably supports the motor shaft 21a. Therefore, the number of parts of the electric actuator 100 can be reduced.

Further, according to the present embodiment, the outer peripheral surface of the portion of the output shaft 41 located inside the motor shaft 21a and the inner peripheral surface of the motor shaft 21a are radially opposed to each other and can be in contact with each other. .. Therefore, even if the motor shaft 21a tends to tilt in the radial direction with respect to the output shaft 41, the inner peripheral surface of the motor shaft 21a can be directly supported by the outer peripheral surface of the output shaft 41. As a result, the area for supporting the motor shaft 21a can be easily increased, and the motor shaft 21a can be supported more stably by the output shaft 41. Therefore, it is possible to further prevent the motor shaft 21a and the output shaft 41 from tilting with each other. Further, the number of parts of the electric actuator 100 can be reduced as compared with the case where another member is provided between the motor shaft 21a and the output shaft 41 in the radial direction.

Further, according to the present embodiment, the output shaft 41 extends from the lower side of the motor shaft 21a to the upper side of the motor shaft 21a through the inside of the motor shaft 21a. Therefore, the output shaft 41 can be arranged over the entire axial direction inside the motor shaft 21a. Thereby, the motor shaft 21a can be more preferably supported by the output shaft 41. Therefore, it is possible to further prevent the motor shaft 21a and the output shaft 41 from tilting with each other.

Further, according to the present embodiment, the first bearing 51 that rotatably supports the portion of the output shaft 41 located below the motor shaft 21a and the output shaft 41 located above the motor shaft 21a. A second bearing 52 that rotatably supports the portion to be used is provided. Therefore, the output shaft 41 can be stably supported by both sides. Since the output shaft 41 is stably supported in this way, the motor shaft 21a can be more preferably supported by the output shaft 41. Therefore, it is possible to further prevent the motor shaft 21a and the output shaft 41 from tilting with each other.

Further, since the output shaft 41 projects on both sides in the axial direction with respect to the motor shaft 21a, it is easy to hold the first bearing 51 and the second bearing 52 that support both sides in the axial direction of the output shaft 41 in the case 10. Therefore, it is possible to prevent the structure of the case 10 from becoming complicated, and it is possible to easily assemble the first bearing 51 and the second bearing 52. In this way, the output shaft 41 is supported by the first bearing 51 and the second bearing 52, and the motor shaft 21a is supported by the output shaft 41. For example, the output shaft 41 is supported by the motor shaft 21a supported by the bearing. The structure of the electric actuator 100 can be suppressed from becoming complicated as compared with the structure that supports the electric actuator 100, and the assembly of the electric actuator 100 can be facilitated.

Further, according to the present embodiment, the case 10 has a case main body 11 that opens upward, and a cover 12 that is fixed to the case main body 11 and closes the upper opening of the case main body 11. The first bearing 51 is held by the case body 11, and the second bearing 52 is held by the cover 12. That is, the second bearing 52 can be held by using the cover 12 that closes the upper opening of the case body 11. Therefore, the number of parts of the electric actuator 100 can be reduced as compared with the case where a member for holding the second bearing 52 is separately provided.

Further, according to the present embodiment, the substrate 80 has a through hole 80a in which the upper portion of the output shaft 41 is passed in the axial direction. Therefore, it is possible to adopt a configuration in which the substrate 80 is arranged between the cover 12 and the motor 20 in the axial direction, and the upper end portion of the output shaft 41 is held by the second bearing 52 held by the cover 12. Further, the substrate 80 can be enlarged in the radial direction. Therefore, it is easy to secure an area on the substrate 80 for arranging the inverter circuit, the first rotation sensor 81, the second rotation sensor 82, and other electronic components (not shown).

Further, according to the present embodiment, a first detected portion 24 whose rotation is detected by the first rotation sensor 81 is provided in a portion of the motor shaft 21a located above the rotor main body 21b. A second detected portion 45 whose rotation is detected by the second rotation sensor 82 is provided in a portion of the output shaft 41 located above the motor shaft 21a. Therefore, both the first rotation sensor 81 and the second rotation sensor 82 can be arranged in the upper portion inside the case 10. As a result, for example, as compared with the case where the first rotation sensor 81 and the second rotation sensor 82 are arranged on different sides in the axial direction in the case 10, the work of assembling the first rotation sensor 81 and the second rotation sensor 82 can be performed. You can easily do it. Specifically, in the present embodiment, both the first rotation sensor 81 and the second rotation sensor 82 can be arranged in the second accommodation portion 11b. Therefore, for example, when the second rotation sensor 82 is arranged in the first accommodation portion 11a. However, it is not necessary to pass the wiring of the second rotation sensor 82 from the inside of the first accommodation portion 11a to the substrate 80 in the second accommodation portion 11b. Therefore, the man-hours and time required for assembling the first rotation sensor 81 and the second rotation sensor 82 can be reduced. Further, for example, as compared with the case where the case 10 is provided with a structure for passing wiring from the inside of the first accommodating portion 11a to the inside of the second accommodating portion 11b, it is possible to suppress the structure of the case 10 from becoming complicated.

In the configuration in which the first rotation sensor 81 and the second rotation sensor 82 can be arranged together on the same side in the axial direction as described above, the motor shaft 21a is a hollow shaft and the output shaft 41 penetrates the inside of the motor shaft 21a. This is possible by projecting to the upper side of the motor shaft 21a. That is, a part of the output shaft 41 connected to the transmission mechanism 30 connected to the lower side of the motor shaft 21a is extended to the upper side of the motor shaft 21a via the inside of the motor shaft 21a, so that the second cover is provided. The detection unit 45 can be provided above the motor shaft 21a, and the second rotation sensor 82 for detecting the second detection unit 45 can be arranged in the upper portion in the case 10.

Further, according to the present embodiment, the first rotation sensor 81 and the second rotation sensor 82 are attached to the substrate 80. Therefore, by arranging the substrate 80 to which the first rotation sensor 81 and the second rotation sensor 82 are attached in the case 10, the first rotation sensor 81 and the second rotation sensor 82 are arranged together in the case 10. be able to. As a result, the man-hours and time required for assembling the first rotation sensor 81 and the second rotation sensor 82 can be further reduced.

Further, according to the present embodiment, the first rotation sensor 81 is attached to the lower surface of the substrate 80, and the second rotation sensor 82 is attached to the upper surface of the substrate 80. That is, the first rotation sensor 81 and the second rotation sensor 82 are attached to the surfaces of the substrate 80 on both sides in the axial direction, which are opposite to each other. Therefore, it is easier to secure a region for mounting each rotation sensor on the board 80 as compared with the case where the first rotation sensor 81 and the second rotation sensor 82 are mounted on the same surface of the board 80.

Further, since the second detected portion 45 is provided on the portion of the output shaft 41 located above the motor shaft 21a, the first detected portion 24 provided on the motor shaft 21a is from the second detected portion 45. Is also easy to place on the lower side. Therefore, by attaching the first rotation sensor 81 to the lower surface of the substrate 80 and the second rotation sensor 82 to the upper surface of the substrate 80, it is easy to arrange each rotation sensor close to each detected portion. .. Thereby, the rotation of each detected portion can be more preferably detected by each rotation sensor. Therefore, the rotation detection accuracy of each shaft by each rotation sensor can be improved.

Further, according to the present embodiment, the first rotation sensor 81 and the first detected portion 24 overlap each other when viewed in the axial direction, and the second rotation sensor 82 and the second detected portion 45 are axially overlapped with each other. Looking at each other, they overlap. Therefore, the rotation of the first rotation sensor 81 and the first detection unit 24 can be made to face each other in the axial direction, and the rotation of the first detection unit 24 can be more easily detected by the first rotation sensor 81. Further, the second rotation sensor 82 and the second detected portion 45 can be made to face each other in the axial direction so that the rotation of the second detected portion 45 can be more easily detected by the second rotation sensor 82. Therefore, the rotation detection accuracy of each shaft by each rotation sensor can be further improved.

Further, the first rotation sensor 81 and the second rotation sensor 82 have different radial positions from each other, and the first detected unit 24 and the second detected unit 45 have different radial positions from each other. Therefore, for example, when the first detected unit 24 and the second detected unit 45 are magnets and the first rotation sensor 81 and the second rotation sensor 82 are magnetic sensors as in the present embodiment, the other detected unit is detected. It is possible to suppress the magnetic field from interfering with the other sensor. Thereby, the rotation of each detected portion can be more preferably detected by each rotation sensor. Therefore, the rotation detection accuracy of each shaft by each rotation sensor can be further improved.

Further, according to the present embodiment, between the lower end of the motor shaft 21a and the upper end of the connecting portion 41a, and the upper end of the motor shaft 21a and the lower end of the mounting member 44. Washers 61 and 62 are provided between the and. Therefore, the washer 61 and 62 can press the motor shaft 21a from both sides in the axial direction. As a result, it is possible to prevent the motor shaft 21a from being displaced in the axial direction with respect to the output shaft 41. Further, as compared with the case where both ends in the axial direction of the motor shaft 21a come into direct contact with the output shaft 41 or the mounting member 44, between the motor shaft 21a and the output shaft 41 and between the motor shaft 21a and the mounting member 44. The friction in the motor shaft 21a and the output shaft 41 can be smoothly rotated relative to each other. In particular, by using the washers 61 and 62 as slip washers, the motor shaft 21a and the output shaft 41 can be more smoothly and easily rotated relative to each other.

Further, according to the present embodiment, the first detected unit 24 and the second detected unit 45 are magnets. The first rotation sensor 81 and the second rotation sensor 82 are magnetic sensors. Therefore, the rotation of the motor shaft 21a and the rotation of the output shaft 41 can be suitably detected by utilizing the magnetic fields generated from the first detected unit 24 and the second detected unit 45. Further, as described above, the rotation detection accuracy obtained by arranging the first rotation sensor 81 and the first detected portion 24 and the second rotation sensor 82 and the second detected portion 45 in a radial direction. The improvement effect can be obtained usefully.

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. The motor shaft may rotatably support the output shaft. Even in this case, it is possible to prevent the motor shaft and the output shaft from tilting each other. Further, in this case, the motor shaft may be supported by the bearing, and the output shaft may not be supported by the bearing. The output shaft does not have to extend to the other side (upper side) in the axial direction from the motor shaft. The entire output shaft may be located inside the motor shaft. Other members may be provided between the inner peripheral surface of the motor shaft and the outer peripheral surface of the output shaft. In this case, one of the motor shaft and the output shaft may rotatably support the other of the motor shaft and the output shaft via the other member. Further, in this case, the other member may be a bearing such as a ball bearing, a needle bearing, or a slide bearing. The type of the first bearing, the type of the second bearing, and the type of the third bearing are not particularly limited. The second bearing does not have to be held by the cover.

The first detected portion may be any portion as long as rotation is detected by the first rotation sensor. The first rotation sensor may be any sensor as long as it can detect the rotation of the motor shaft by detecting the rotation of the first detected portion. The second detected portion may be any portion as long as the rotation is detected by the second rotation sensor. The second rotation sensor may be any sensor as long as it can detect the rotation of the output shaft by detecting the rotation of the second detected portion. The first detected portion may be a part of the motor shaft. The second detected portion may be a part of the output shaft. The first rotation sensor and the second rotation sensor may be optical sensors. The first rotation sensor may be a resolver stator and the first detected portion may be a resolver rotor. The second rotation sensor may be a resolver stator and the second detected portion may be a resolver rotor. The first rotation sensor and the second rotation sensor may be magnetic sensors other than the Hall element. The first rotation sensor and the second rotation sensor may be magnetoresistive elements.

The first rotation sensor may be attached to the other side (upper side) in the axial direction of the substrate, and the second rotation sensor may be attached to one side (lower side) in the axial direction of the substrate. The first rotation sensor and the second rotation sensor may be attached to different members. The first rotation sensor and the second rotation sensor may be arranged on different sides in the axial direction in the case. The first rotation sensor and the second rotation sensor may not be provided. A washer may not be provided between the motor shaft and the connecting portion and between the motor shaft and the mounting member.

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 may be a speed-increasing mechanism or a mechanism that does not shift the rotation of the motor shaft. When the transmission mechanism is a deceleration mechanism, the structure of the deceleration mechanism is not particularly limited. The plurality of protrusions may be provided in the external tooth gear, and the plurality of holes may be provided in the output flange portion. In this case, the protruding portion protrudes from the external tooth gear toward the output flange portion and is inserted into the hole portion.

The application of the electric actuator to which the present invention is applied is not particularly limited. The electric actuator may be mounted on a shift-by-wire actuator device driven based on the shift operation of the driver. Further, the electric actuator may be mounted on a device other than the vehicle. As described above, the configurations described in the present specification can be appropriately combined within a range that does not contradict each other.

10 ... Case, 11 ... Case body, 12 ... Cover, 20 ... Motor, 21 ... Rotor, 21a ... Motor shaft, 21b ... Rotor body, 21d ... Eccentric shaft part, 24 ... First detected part, 30 ... Transmission mechanism, 31 ... External tooth gear, 31b ... Hole, 32 ... Internal tooth gear, 41 ... Output shaft, 41a ... Connecting part, 41b ... Stretching part, 42 ... Output flange part, 43 ... Protruding part, 44 ... Mounting member, 45 ... 2nd detected part, 51 ... 1st bearing, 52 ... 2nd bearing, 53 ... 3rd bearing (bearing), 61, 62 ... washer, 81 ... 1st rotation sensor, 82 ... 2nd rotation sensor, 100 ... electric Actuator, DS ... Driven shaft, J1 ... Motor shaft, J2 ... Eccentric shaft

Claims (9)

A motor with a motor shaft that can rotate around the motor shaft,
A transmission mechanism connected to one side in the axial direction of the motor shaft, and
An output shaft that extends in the axial direction of the motor shaft and transmits the rotation of the motor shaft via the transmission mechanism.
Equipped with
The motor shaft is a hollow shaft.
At least a portion of the output shaft is located inside the motor shaft and is located inside the motor shaft.
An electric actuator in which one of the motor shaft and the output shaft rotatably supports the other of the motor shaft and the output shaft. The electric actuator according to claim 1, wherein the outer peripheral surface of the portion of the output shaft located inside the motor shaft and the inner peripheral surface of the motor shaft are radially opposed to each other and are in contact with each other. .. The electric actuator according to claim 1 or 2, wherein the output shaft extends from one side in the axial direction of the motor shaft, passes through the inside of the motor shaft, and extends to the other side in the axial direction of the motor shaft. A first bearing that rotatably supports a portion of the output shaft located on one side in the axial direction from the motor shaft, and
A second bearing that rotatably supports the portion of the output shaft located on the other side in the axial direction from the motor shaft,
Further prepare
The electric actuator according to claim 3, wherein the output shaft rotatably supports the motor shaft. Further provided with a case for accommodating the motor and the transmission mechanism inside.
The case is
The case body that opens on the other side in the axial direction,
A cover fixed to the case body and closing the opening on the other side in the axial direction of the case body,
Have,
The first bearing is held by the case body and is held.
The electric actuator according to claim 4, wherein the second bearing is held by the cover. The first rotation sensor capable of detecting the rotation of the motor shaft and
A second rotation sensor capable of detecting the rotation of the output shaft and
Further prepare
The motor has a rotor body fixed to the outer peripheral surface of the motor shaft.
A first detected portion for detecting rotation by the first rotation sensor is provided on a portion of the motor shaft located on the other side in the axial direction from the rotor main body.
3. The electric actuator according to one item. The first detected portion and the second detected portion are magnets.
The electric actuator according to claim 6, wherein the first rotation sensor and the second rotation sensor are magnetic sensors. Further, a mounting member fixed to the outer peripheral surface of the portion of the output shaft located on the other side in the axial direction from the motor shaft is further provided.
The second detected portion is attached to the output shaft via the attachment member, and is attached to the output shaft.
The output shaft is
The connecting part to which the driven shaft is connected and
An extension portion extending from the connecting portion to the other side in the axial direction and passing through the inside of the motor shaft,
Have,
The outer diameter of the connecting portion is larger than the outer diameter of the stretched portion.
Between one end of the motor shaft in the axial direction and the other end of the connecting portion in the axial direction, and between the other end of the motor shaft in the axial direction and one end of the mounting member in the axial direction. The electric actuator according to claim 6 or 7, wherein a washer is provided between the portions. The motor shaft has an eccentric shaft portion centered on an eccentric shaft that is eccentric with respect to the motor shaft.
The transmission mechanism is
An external tooth gear connected to the eccentric shaft portion via a bearing,
An internal tooth gear that surrounds the radial outer side of the external tooth gear and meshes with the external tooth gear.
An output flange portion that protrudes radially outward from a portion of the output shaft located on one side in the axial direction with respect to the motor shaft and is arranged so as to face one side in the axial direction of the external tooth gear.
A plurality of protruding portions arranged so as to project from one of the output flange portion and the external tooth gear toward the other and surround the motor shaft.
Have,
The other of the output flange portion and the external tooth gear has a plurality of holes arranged so as to surround the motor shaft.
The plurality of protrusions are inserted into each of the plurality of holes, and the external tooth gear is swingably supported around the motor shaft via the inner surface of the holes. The electric actuator according to any one of 8 to 8.

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