Electric actuator and method for manufacturing electric actuator

Abstract

An electric actuator and a method for manufacturing an electric actuator, the electric actuator comprising: a rotor having a motor shaft rotatable about a central axis; a stator disposed on the outside in the radial direction of the rotor; a motor housing having an opening portion that opens on one side in the axial direction; and a cover member that closes the opening. The motor housing and the cover member are each made of resin. The cover member has a first support portion that supports a portion of the motor shaft positioned closer to one side in the axial direction than the stator, and the cover member has a circular plate shape centered on the central axis. The motor housing includes: a bottom wall portion provided with a second support portion that supports a portion of the motor shaft closer to the other side in the axial direction than the stator and a through hole through which the motor shaft passes in the axial direction, the bottom wall portion expanding in a direction intersecting the axial direction; and a cover fixing part which is in a ring shape surrounding the central axis, and which is in contact with the surface of the cover member facing the other side in the axial direction in the axial direction. The cover member and the cover fixing portion are joined to each other over the entire circumferential range in the circumferential direction.

Description

Technical Field

[0001] The present invention relates to an electric actuator and a method for manufacturing the electric actuator. Background Art

[0002] There is known an electric actuator in which a housing for housing a motor is constituted by a motor case that supports one axial end of a motor shaft and a cover that supports the other axial end of the motor shaft (for example, Patent Document 1).

[0003] Patent Document 1: Japanese Patent Application Publication No. 2022-053986

[0004] In the electric actuator as described above, in the manufacturing process of the electric actuator, one axial end of the motor shaft is assembled to the support portion of the motor housing, and the other axial end of the motor shaft is assembled to the support portion of the cover while the two axial ends of the motor shaft are held by a jig or the like, thereby improving the coaxiality between the motor shaft and the housing. In this case, holes for passing the jig or the like for holding the motor shaft need to be provided on the motor housing and the cover, respectively. Therefore, in order to improve the airtightness of the electric actuator, the hole needs to be sealed by a cap or the like, and the number of components of the electric actuator increases. Summary of the invention

[0005] In view of the above circumstances, one object of the present invention is to provide an electric actuator and a method for manufacturing the electric actuator that can improve the coaxiality between a motor shaft and a housing while suppressing an increase in the number of parts of the electric actuator.

[0006] One embodiment of the present invention is an electric actuator, which has: a rotor having a motor shaft that can rotate around a central axis; a stator that is arranged radially outside the rotor; a motor housing having an opening that opens on one side in the axial direction, the motor housing accommodating the rotor and the stator inside; and a cover member that closes the opening. The motor housing and the cover member are each made of resin. The cover member has a first support portion that supports a portion of the motor shaft that is located on one side of the axial direction than the stator, and the cover member is in the shape of a disk centered on the central axis. The motor housing has a bottom wall portion that is provided with a second support portion that supports a portion of the motor shaft that is located on the other side of the axial direction than the stator and a through hole for the motor shaft to pass through in the axial direction, the bottom wall portion extending in a direction intersecting the axial direction; and a cover fixing portion that is in an annular shape surrounding the central axis and axially contacts a surface of the cover member that faces the other side in the axial direction. The cover member and the cover fixing portion are engaged with each other over the entire circumference.

[0007] One embodiment of the present invention is a method for manufacturing an electric actuator, the electric actuator comprising: a rotor having a motor shaft rotatable about a central axis; a stator disposed radially outside the rotor; a motor housing having an opening portion opened on one side in the axial direction, the motor housing accommodating the rotor and the stator inside; and a cover member closing the opening portion, wherein the method for manufacturing the electric actuator comprises an assembly step of assembling the rotor and the cover member to the motor housing, respectively. The motor housing and the cover member are each made of resin. The cover member has a first support portion that supports a portion of the motor shaft located on one side of the axial direction relative to the stator, and the cover member is in the shape of a disk centered on the central axis. The motor housing has a bottom wall portion that is provided with a second support portion and a through hole for the motor shaft to pass through in the axial direction, the bottom wall portion extending in a direction intersecting the axial direction; and a cover fixing portion that is in the shape of a ring surrounding the central axis. The assembly process includes the following steps: a first step of inserting the rotor into the interior of the motor housing through the opening portion so that the second support portion supports the portion of the motor shaft on the other axial side and allows the motor shaft to pass through the through hole; a second step of fixing the portion of the motor shaft that protrudes to the other axial side than the bottom wall portion through the through hole to an axis fixing fixture; a third step of moving the cover component from one axial side to the other axial side of the motor housing so that the portion of the motor shaft on one axial side is supported by the first support portion; and a fourth step of rotating the cover component around the central axis to rotationally weld the surface of the cover component facing the other axial side to the cover fixing portion.

[0008] According to one aspect of the present invention, in an electric actuator and a method for manufacturing the electric actuator, it is possible to improve the coaxiality between a motor shaft and a housing while suppressing an increase in the number of components of the electric actuator. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a perspective view showing an electric actuator according to one embodiment.

[0010] Figure 2 This is a cross-sectional view showing an electric actuator according to an embodiment.

[0011] Figure 3 1 is a flowchart showing an assembly process according to one embodiment.

[0012] Figure 4 This is a first cross-sectional view showing an assembly process according to one embodiment.

[0013] Figure 5 This is a second cross-sectional view showing an assembly process according to one embodiment.

[0014] Figure 6 This is a third cross-sectional view showing an assembling process according to one embodiment.

[0015] Description of symbols

[0016] 1: electric actuator; 12: motor housing; 12a: opening; 13b: cover fixing portion; 14: bottom wall; 14a: second supporting portion; 14c: through hole; 17: cover member; 17a: first supporting portion; 17b: cover welding portion; 20: rotor; 23: motor shaft; 30: stator; 60: transmission mechanism; 66: output shaft; 91: first bearing; 92: second bearing; J1: center axis; Pf: assembly process; P01: first process; P02: second process; P03: third process; P04: fourth process. DETAILED DESCRIPTION

[0017] In each drawing, the Z-axis direction is an up-down direction with the positive side (+Z side) as the upper side and the negative side (-Z side) as the lower side. In this embodiment, the upper side (+Z side) corresponds to one axial side, and the lower side (-Z side) corresponds to the other axial side.

[0018] In each of the drawings, the first direction D1 is a direction perpendicular to the Z-axis direction. In the present embodiment, the first direction D1 is the left-right direction of the electric actuator. In the following description, the side to which the arrow of the first direction D1 points (+D1 side) is referred to as the "right side", and the side opposite to the side to which the arrow of the first direction D1 points (-D1 side) is referred to as the "left side".

[0019] In each of the drawings, the second direction D2 is a direction perpendicular to both the Z-axis direction and the first direction D1. In the present embodiment, the second direction D2 is the front-rear direction of the electric actuator. In the following description, the side to which the arrow of the second direction D2 points (+D2 side) is referred to as the "rear side", and the side opposite to the side to which the arrow of the second direction D2 points (-D2 side) is referred to as the "front side". In addition, the upper side, the lower side, the right side, the left side, the front side, and the rear side are merely names used to illustrate the relative positional relationship of each part, and the actual configuration relationship, etc. may also be a configuration relationship, etc. other than the configuration relationship, etc. represented by these names.

[0020] The direction in which the center axis J1 shown in each figure extends is parallel to the Z-axis direction. In the present embodiment, the center axis J1 is a virtual axis. The center axis J1 is the center axis of the motor shaft. In the following description, the direction parallel to the center axis J1 is referred to as the "axial direction". The radial direction centered on the center axis J1 is referred to as the "radial direction". The circumferential direction centered on the center axis J1 is referred to as the "circumferential direction". In each figure, the circumferential direction is indicated by the arrow θ1.

[0021] Figure 1The electric actuator 1 of the present embodiment shown in FIG. 1 is mounted on a vehicle. More specifically, the electric actuator 1 is mounted on, for example, an actuator device of a parking-by-wire system that is driven according to a shift operation by a driver of the vehicle. Figure 2 As shown, the electric actuator 1 includes a housing 10 , a motor 9 , a transmission mechanism 60 , an output shaft 66 , and a circuit board 80 .

[0022] The housing 10 accommodates the motor 9, the transmission mechanism 60, the output shaft 66 and the circuit board 80. The housing 10 has a housing body 11, a cover member 17 and a lower housing 18. In the present embodiment, the housing body 11 and the cover member 17 are made of resin. The lower housing 18 can be made of resin or metal. The housing body 11 is cylindrical and surrounds the central axis J1. The housing body 11 has a lower opening portion 11b opened at the lower side. The housing body 11 has a motor housing 12, a connector housing 15 and a fixing portion 11a.

[0023] The motor housing 12 is roughly cylindrical with the housing axis J2 as the center. In the present embodiment, the housing axis J2 is an imaginary axis extending in a direction parallel to the center axis J1. The housing axis J2 overlaps with the center axis J1. Therefore, the motor housing 12 is roughly cylindrical with the center axis J1 as the center and extending in the axial direction. The motor housing 12 is made of resin. The motor housing 12 accommodates the motor 9 inside. The motor housing 12 is open on the lower side. The motor housing 12 has an opening 12a that is open on the upper side, that is, on one axial side (+Z side). The motor housing 12 has a peripheral wall portion 13, a cover fixing portion 13b and a bottom wall portion 14. In addition, in the present invention, regarding the overlap of the axis of one component with the axis of the other component, in addition to the case where the axis of one component completely overlaps with the axis of the other component, it also includes the case where the coaxiality of the components of both parties is offset by the design tolerance obtained by adding the design tolerance of the roundness of one component and the design tolerance of the roundness of the other component.

[0024] The peripheral wall portion 13 is substantially cylindrical and extends axially with the central axis J1 as the center. The peripheral wall portion 13 surrounds the motor 9 from the radially outer side. The peripheral wall portion 13 has a step surface 13a. The step surface 13a is a step surface facing upward. The step surface 13a is a part of the inner side surface of the peripheral wall portion 13. When viewed from the axial direction, the step surface 13a is annular with the central axis J1 as the center.

[0025] The cover fixing portion 13b protrudes upward from the peripheral wall portion 13. The cover fixing portion 13b is in the shape of a ring surrounding the central axis J1. In the present embodiment, the cover fixing portion 13b is in the shape of a circular ring centered on the central axis J1. The upper end of the cover fixing portion 13b is the upper end of the motor housing 12. The cover fixing portion 13b is located on the upper side of the motor housing 12, that is, the end on one axial side (+Z side). The inner diameter of the cover fixing portion 13b is the same size as the inner diameter of the peripheral wall portion 13. The outer diameter of the cover fixing portion 13b is smaller than the outer diameter of the peripheral wall portion 13.

[0026] The bottom wall portion 14 is in a generally disk-like shape extending in a direction intersecting the axial direction. In the present embodiment, the bottom wall portion 14 extends in a direction perpendicular to the axial direction. The bottom wall portion 14 is in a generally disk-like shape centered on the central axis J1. The radially outer end of the bottom wall portion 14 is connected to the lower end of the peripheral wall portion 13. The bottom wall portion 14 is provided with a second supporting portion 14a, a through hole 14c, a first bottom wall hole portion 14e, a second bottom wall hole portion 14f and a first substrate holding portion 14h.

[0027] The second support portion 14a protrudes upward from the bottom wall portion 14. The second support portion 14a is cylindrical with the center axis J1 as the center. The second support portion 14a is open at the upper side. The through hole 14c is a hole that penetrates the bottom wall portion 14 in the axial direction. In the present embodiment, when viewed from the axial direction, the through hole 14c is roughly circular with the center axis J1 as the center. Alternatively, when viewed from the axial direction, the through hole 14c may be in other shapes such as an angular shape. The inner diameter of the through hole 14c is smaller than the inner diameter of the second support portion 14a.

[0028] The first bottom wall hole portion 14e is a hole that penetrates the bottom wall portion 14 in the axial direction. The first bottom wall hole portion 14e is arranged at a position radially outward from the second supporting portion 14a. Although the illustration is omitted, in the present embodiment, three first bottom wall hole portions 14e are provided on the bottom wall portion 14. Each first bottom wall hole portion 14e is arranged at intervals from each other along the circumferential direction. The second bottom wall hole portion 14f is a hole that penetrates the bottom wall portion 14 in the axial direction. When viewed from the axial direction, the second bottom wall hole portion 14f is in a circular shape centered on the output axis J4. The second bottom wall hole portion 14f is arranged on the left side (-D1 side) of the second supporting portion 14a. The second bottom wall hole portion 14f is arranged at intervals from the second supporting portion 14a in the first direction D1.

[0029] In the present embodiment, the output axis J4 is an imaginary axis extending in a direction parallel to the center axis J1. The output axis J4 is located on the left side (-D1 side) of the center axis J1. In the following description, the radial direction centered on the output axis J4 is referred to as the "output radial direction", and the circumferential direction centered on the output axis J4 is referred to as the "output circumferential direction". The output circumferential direction is indicated by an arrow θ4 in each figure.

[0030] The first substrate holding portion 14h holds the circuit substrate 80. The first substrate holding portion 14h is in a generally cylindrical shape protruding downward from the bottom wall portion 14. The first substrate holding portion 14h is arranged at a position radially outward from the first bottom wall hole portion 14e. Although not shown in the figure, in the present embodiment, three first substrate holding portions 14h are provided on the bottom wall portion 14. The first bottom wall holes 14e are arranged at intervals along the circumferential direction. Each first substrate holding portion 14h has a first shaft portion 14i, a first insertion portion 14j, and a first substrate supporting portion 14k. The first shaft portion 14i is in a generally cylindrical shape protruding downward from the bottom wall portion 14. The first insertion portion 14j is in a generally cylindrical shape protruding downward from the first shaft portion 14i. The outer diameter of the first insertion portion 14j is smaller than the outer diameter of the first shaft portion 14i. The first substrate supporting portion 14k protrudes downward from the first insertion portion 14j. The outer diameter of the first substrate supporting portion 14k is larger than the outer diameter of the first insertion portion 14j.

[0031] The connector housing 15 is in the shape of a tube extending in the axial direction. The connector housing 15 is open at the bottom. The connector housing 15 is arranged on the left side (-D1 side) of the motor housing 12. The connector housing 15 is connected to the motor housing 12 in the first direction D1. Figure 1 As shown, when viewed from the axial direction, the connector housing 15 is a generally rectangular shape with the right side (+D1 side) part being recessed in an arc shape toward the left side. Figure 2 As shown, the connector housing 15 is provided with a second board holding portion 15 a and a connector housing portion 16 .

[0032] The second substrate holding portion 15a holds the circuit substrate 80. The second substrate holding portion 15a is in a generally cylindrical shape protruding downward from the connector housing 15. Although not shown in the figure, in the present embodiment, two second substrate holding portions 15a are provided in the connector housing 15. Each second substrate holding portion 15a is arranged at intervals in the second direction D2. Each second substrate holding portion 15a has a second shaft portion 15b, a second insertion portion 15c, and a second substrate supporting portion 15d. The second shaft portion 15b is in a generally cylindrical shape protruding downward from the connector housing 15. The second insertion portion 15c is in a generally cylindrical shape protruding downward from the second shaft portion 15b. The outer diameter of the second insertion portion 15c is smaller than the outer diameter of the second shaft portion 15b. The second substrate supporting portion 15d protrudes downward from the second insertion portion 15c. The outer diameter of the second substrate supporting portion 15d is larger than the outer diameter of the second insertion portion 15c.

[0033] like Figure 1 As shown in FIG. 1 , the connector housing portion 16 is in a generally square cylindrical shape that protrudes upward from the connector housing 15. The connector housing portion 16 is open at the upper side. Figure 2As shown, the connector housing 16 holds a plurality of connector pins 97a. Each connector pin 97a extends in the axial direction. The upper end of each connector pin 97a is located inside the connector housing 16. The lower end of each connector pin 97a is connected to the circuit board 80.

[0034] like Figure 1 As shown, the fixing portion 11a protrudes radially outward from the motor housing 12 or the connector housing 15. A hole that penetrates the fixing portion 11a in the axial direction is provided in the fixing portion 11a. In the present embodiment, the housing body 11 has three fixing portions 11a. One fixing portion 11a protrudes to the right side (+D1 side) from the peripheral wall portion 13. One of the other two fixing portions 11a protrudes from the connector housing 15 to the front side (-D2 side), and the other fixing portion 11a protrudes from the connector housing 15 to the rear side (+D2 side). When a bolt not shown in the figure passes through the hole of each fixing portion 11a in the axial direction and is screwed into a threaded hole provided in the vehicle not shown in the figure, the electric actuator 1 is fixed to the vehicle body.

[0035] like Figure 2 As shown, the cover component 17 is in the shape of a disk centered on the cover axis J3. In the present embodiment, the cover axis J3 is an imaginary axis extending in a direction parallel to the center axis J1. The cover axis J3 overlaps with the center axis J1. Thus, the cover component 17 is in the shape of a disk centered on the center axis J1. The cover component 17 is arranged on the upper side of the motor housing 12. The cover component 17 closes the opening 12a of the motor housing 12 from the upper side. The cover component 17 has a first supporting portion 17a, a cover welding portion 17b and a cover annular portion 17d.

[0036] The first support portion 17a protrudes downward from the cover member 17. The first support portion 17a is cylindrical with the center axis J1 as the center. The first support portion 17a is open at the bottom. The cover welding portion 17b is a portion of the radial outer edge of the surface of the cover member 17 facing downward. The cover welding portion 17b extends along the radial outer edge of the cover member 17 over the entire circumference. When viewed from the axial direction, the cover welding portion 17b is roughly annular with the center axis J1 as the center. The cover welding portion 17b is in contact with the cover fixing portion 13b in the axial direction. That is, the cover fixing portion 13b is in contact with the surface of the cover member 17 facing downward, that is, the other axial side (-Z side) in the axial direction. The cover welding portion 17b and the cover fixing portion 13b are joined by welding. Thus, the cover member 17 is fixed to the motor housing 12. In addition, the cover member 17 and the cover fixing portion 13b are joined to each other over the entire circumference. Thus, the cover member 17 and the motor case 12 are sealed over the entire circumference. As will be described later, in the present embodiment, the cover welding portion 17b and the cover fixing portion 13b are joined by spin welding.

[0037] The cover annular portion 17d protrudes downward from the radially outer end of the cover component 17. The cover annular portion 17d is in the shape of an annulus centered on the central axis J1. The cover annular portion 17d is arranged radially outside the cover fixing portion 13b. The cover annular portion 17d and the cover fixing portion 13b are radially opposite. In the present embodiment, the cover annular portion 17d may be arranged with a gap in the radial direction from the cover fixing portion 13b, or may be arranged in contact with the cover fixing portion 13b in the radial direction. The cover annular portion 17d is arranged with a gap in the axial direction from the peripheral wall portion 13.

[0038] The lower shell 18 is in the shape of a box that is open on the upper side. The lower shell 18 is arranged on the lower side of the shell body 11. The lower shell 18 closes the lower opening portion 11b of the shell body 11 from the lower side. The lower shell 18 is fixed to the lower end of the shell body 11. The lower shell 18 and the shell body 11 can be fixed by bonding, or by screws not shown in the figure. The interior of the lower shell 18 is isolated from the interior of the motor housing 12 by the bottom wall portion 14. The interior of the lower shell 18 is connected to the interior of the connector housing 15. The transmission mechanism 60 is accommodated in the interior of the lower shell 18. The lower shell 18 has a first wall portion 18a and a second wall portion 18b.

[0039] The first wall portion 18a is in the shape of a tube protruding in the axial direction. The first wall portion 18a is open on the upper side. The first wall portion 18a surrounds the central axis J1 and the output axis J4. The right side (+D1 side) portion of the first wall portion 18a is in the shape of a ring centered on the central axis J1. The right side portion of the first wall portion 18a is fixed to the lower end of the peripheral wall portion 13. The left side (-D1 side) portion of the first wall portion 18a is in the shape of a roughly rectangular opening on the right side. The left side portion of the first wall portion 18a is fixed to the lower end of the connector housing 15. Thus, the lower housing 18 is fixed to the lower end of the housing body 11.

[0040] The second wall portion 18b is in the shape of a plate extending in a direction perpendicular to the axial direction. The outer edge of the second wall portion 18b is connected to the lower end of the first wall portion 18a. The second wall portion 18b is provided with a third support portion 18d and an output hole portion 18f. The third support portion 18d protrudes downward from the second wall portion 18b. The third support portion 18d is in the shape of a cylinder centered on the central axis J1. The third support portion 18d is open on the upper side. The output hole portion 18f is a hole that penetrates the second wall portion 18b in the axial direction. When viewed from the axial direction, the output hole portion 18f is in the shape of a circle centered on the output axis J4.

[0041] The motor 9 has a rotor 20 and a stator 30. The rotor 20 and the stator 30 are housed inside the motor housing 12. The rotor 20 can rotate around the central axis J1. The rotor 20 has a rotor core 21, a magnet (not shown) and a motor shaft 23. The rotor core 21 is annular centered around the central axis J1. The magnet (not shown) is fixed to the rotor core 21. In this embodiment, a plurality of magnets are arranged at intervals in the circumferential direction.

[0042] The motor shaft 23 is rotatable about the central axis J1. The motor shaft 23 is in a generally cylindrical shape extending axially about the central axis J1. The motor shaft 23 extends axially across the interior of the motor housing 12 and the interior of the lower housing 18. The motor shaft 23 passes through the interior of the rotor core 21 in the axial direction. The rotor core 21 is fixed to the outer peripheral surface of the motor shaft 23. The portion of the motor shaft 23 that is lower than the rotor core 21 passes through the through hole 14c in the axial direction and protrudes into the interior of the lower housing 18. That is, the portion of the motor shaft 23 that is lower than the bottom wall portion 14 protrudes into the interior of the lower housing 18.

[0043] The stator 30 is arranged radially outside the rotor 20. The stator 30 is arranged to face the rotor 20 with a gap therebetween in the radial direction. The stator 30 includes a stator core 31, an insulator 32, and a coil portion 35.

[0044] The stator core 31 is in an annular shape that surrounds the rotor core 21 from the radial outside. The stator core 31 and the rotor 20 are spaced apart in the radial direction and face each other. The stator core 31 has a core back 31a and a plurality of teeth 31b. The core back 31a is in an annular shape centered on the central axis J1. The core back 31a is fixed to the inner circumferential surface of the peripheral wall portion 13. Thus, the stator 30 is fixed to the housing body 11. The surface of the core back 31a facing downward is in contact with the step surface 13a in the axial direction. Thus, the axial position of the stator 30 relative to the housing body 11 is determined. Each tooth 31b protrudes radially inward from the core back 31a. Although not shown in the figure, each tooth 31b is arranged at intervals along the circumferential direction. The insulator 32 is mounted on the stator core 31. The insulator 32 insulates the stator core 31 from the coil portion 35.

[0045] The coil portion 35 includes a plurality of coil main bodies 35a and coil lead wires 35b. Each coil main body 35a is mounted on a different tooth portion 31b via an insulating member 32. The coil lead wires 35b are led out from the coil main body 35a to the lower side and pass through the first bottom wall hole 14e of the bottom wall portion 14 in the axial direction. The lower end of the coil lead wire 35b is connected to the circuit substrate 80. Thus, the coil portion 35 is electrically connected to the circuit substrate 80.

[0046] The first bearing 91 is in the shape of an annulus centered on the central axis J1. The first bearing 91 is mounted on the inner circumferential surface of the first supporting portion 17a. The first bearing 91 supports the portion of the motor shaft 23 that is above the stator 30 so as to be rotatable around the central axis J1. Thus, the first supporting portion 17a supports the portion of the motor shaft 23 that is above the stator 30, that is, on one axial side (+Z side), via the first bearing 91. That is, the first supporting portion 17a supports the portion of the motor shaft 23 that is above the stator 30. In the present embodiment, the first bearing 91 is a sliding bearing. The first bearing 91 may also be a ball bearing.

[0047] The second bearing 92 is in the shape of an annulus centered on the central axis J1. The second bearing 92 is mounted on the inner circumferential surface of the second supporting portion 14a. The second bearing 92 supports the portion of the motor shaft 23 that is lower than the stator 30 so as to be rotatable around the central axis J1. Thus, the second supporting portion 14a supports the portion of the motor shaft 23 that is lower than the stator 30, that is, on the other axial side (-Z side) via the second bearing 92. That is, the second supporting portion 14a supports the portion of the motor shaft 23 that is lower than the stator 30. In the present embodiment, the second bearing 92 is a ball bearing. The second bearing 92 may also be a sliding bearing.

[0048] The third bearing 93 is annular with the center axis J1 as the center. The third bearing 93 is mounted on the inner peripheral surface of the third support portion 18d. The third bearing 93 supports the lower end of the motor shaft 23 so that it can rotate around the center axis J1. In the present embodiment, the third bearing 93 is a ball bearing. The third bearing 93 may also be a sliding bearing.

[0049] The circuit substrate 80 is in the shape of a plate extending in a direction perpendicular to the axial direction. The circuit substrate 80 is arranged at a position lower than the stator 30 and the bottom wall portion 14. As described above, a plurality of connector pins 97a are connected to the circuit substrate 80. When the plurality of connector pins 97a are electrically connected to an external power source not shown in the figure, power is supplied from the external power source to the circuit substrate 80. In addition, as described above, a plurality of coil lead wires 35b are connected to the circuit substrate 80. Thus, power from the external power source is supplied to the coil portion 35 via the circuit substrate 80. The circuit substrate 80 is provided with a first substrate hole 80a, a second substrate hole 80b, a third substrate hole 80c and a fourth substrate hole 80d. The first substrate hole 80a, the second substrate hole 80b, the third substrate hole 80c and the fourth substrate hole 80d are holes respectively penetrating the circuit substrate 80 in the axial direction.

[0050] When viewed in the axial direction, the first substrate hole 80a is roughly circular. Although not shown in the figure, in the present embodiment, three first substrate holes 80a are provided on the circuit substrate 80. When viewed in the axial direction, each first substrate hole 80a overlaps with a first substrate holding portion 14h that is different from each other. The first insertion portion 14j passes through each first substrate hole 80a in the axial direction. The surface of the circuit substrate 80 facing upward is in contact with the first shaft portion 14i in the axial direction. The surface of the circuit substrate 80 facing downward is supported in the axial direction by the first substrate supporting portion 14k. Thus, the circuit substrate 80 is held in the housing 10.

[0051] When viewed in the axial direction, the second substrate hole 80b is roughly circular. Although not shown in the figure, in the present embodiment, two second substrate holes 80b are provided on the circuit substrate 80. When viewed in the axial direction, each second substrate hole 80b overlaps with a second substrate holding portion 15a that is different from each other. The second insertion portion 15c passes through each second substrate hole 80b in the axial direction. The surface of the circuit substrate 80 facing upward is in contact with the second shaft portion 15b in the axial direction. The surface of the circuit substrate 80 facing downward is supported in the axial direction by the second substrate supporting portion 15d. Thus, the circuit substrate 80 is held in the housing 10.

[0052] When viewed in the axial direction, the third substrate hole 80c is substantially circular with the central axis J1 as the center. The motor shaft 23 passes through the third substrate hole 80c in the axial direction. When viewed in the axial direction, the fourth substrate hole 80d is substantially circular with the output axis J4 as the center. The output shaft 66 passes through the fourth substrate hole 80d in the axial direction.

[0053] The transmission mechanism 60 is arranged below the circuit board 80. The transmission mechanism 60 is housed inside the lower housing 18. The transmission mechanism 60 is connected to both the motor shaft 23 and the output shaft 66. The transmission mechanism 60 is connected to a portion of the motor shaft 23 located below the bottom wall portion 14, that is, at the other axial side (-Z side). The transmission mechanism 60 transmits the rotation of the motor shaft 23 to the output shaft 66. In the present embodiment, the transmission mechanism 60 decelerates the rotation of the rotor 20 and transmits it to the output shaft 66. The transmission mechanism 60 may also increase the speed of the rotation of the rotor 20 and transmit it to the output shaft 66, or may transmit the rotation of the same speed as the rotation of the rotor 20 to the output shaft 66. The transmission mechanism 60 includes a motor gear 61, a first-stage gear 62, a second-stage gear 63, and an output gear 64. The rotation of the motor shaft 23 is sequentially transmitted to the motor gear 61, the first-stage gear 62, the second-stage gear 63, the output gear 64, and the output shaft 66.

[0054] The motor gear 61 transmits the rotation of the motor shaft 23 to the first-stage gear 62. The motor gear 61 is in the shape of an annular plate centered on the central axis J1. The inner circumferential surface of the motor gear 61 is fixed to the motor shaft 23. Thus, the motor gear 61 rotates around the central axis J1 together with the motor shaft 23. A motor gear portion is provided on the radially outward surface of the motor gear 61.

[0055] The first stage gear 62 transmits the rotation of the motor gear 61 to the second stage gear 63. The first stage gear 62 is in the shape of an annular plate centered on the output axis J4. The output shaft 66 passes through the interior of the first stage gear 62 in the axial direction. The first stage gear 62 is supported by the output shaft 66 so as to be rotatable around the output axis J4. The first stage gear 62 has a first large diameter gear 62a and a first small diameter gear 62b. The first large diameter gear 62a and the first small diameter gear 62b are part of the same single component.

[0056] The first large diameter gear 62a is in the shape of an annular plate centered on the output axis J4. The first large diameter gear 62a is radially opposed to the motor gear 61. A first large diameter gear portion meshing with the motor gear portion is provided on the surface of the first large diameter gear 62a facing the radial outer side of the output. The number of teeth of the first large diameter gear portion is greater than the number of teeth of the motor gear portion. Thus, the rotation of the motor shaft 23 and the motor gear 61 is decelerated and transmitted to the first stage gear 62. The first small diameter gear 62b is in the shape of an annular plate centered on the output axis J4. The first small diameter gear 62b is arranged on the upper side of the first large diameter gear 62a. A first small diameter gear portion is provided on the surface of the first small diameter gear 62b facing the radial outer side of the output.

[0057] The second stage gear 63 transmits the rotation of the first stage gear 62 to the output gear 64. The second stage gear 63 is in the shape of an annular plate centered on the central axis J1. The motor shaft 23 passes through the interior of the second stage gear 63 in the axial direction. The second stage gear 63 is supported by the motor shaft 23 so as to be rotatable around the central axis J1. The second stage gear 63 has a second large diameter gear 63a and a second small diameter gear 63b. The second large diameter gear 63a and the second small diameter gear 63b are part of the same single component.

[0058] The second large diameter gear 63a is in the shape of an annular plate centered on the central axis J1. The second large diameter gear 63a is radially opposed to the first small diameter gear 62b. A second large diameter gear portion meshing with the first small diameter gear portion is provided on the radially outward surface of the second large diameter gear 63a. The number of teeth of the second large diameter gear portion is greater than the number of teeth of the first small diameter gear portion. Thus, the rotation of the first stage gear 62 is decelerated and transmitted to the second stage gear 63. The second small diameter gear 63b is in the shape of an annular plate centered on the central axis J1. The second small diameter gear 63b is arranged on the upper side of the second large diameter gear 63a. A second small diameter gear portion is provided on the radially outward surface of the second small diameter gear 63b.

[0059] The output gear 64 transmits the rotation of the second-stage gear 63 to the output shaft 66. The output gear 64 is in the shape of an annular plate centered on the output axis J4. The inner circumferential surface of the output gear 64 is fixed to the output shaft 66. Thus, the output shaft 66 rotates together with the output gear 64 around the output axis J4. An output gear portion meshing with the second small-diameter gear portion is provided on the surface of the output gear 64 facing the output radial outer side. The number of teeth of the output gear portion is greater than the number of teeth of the second small-diameter gear portion. Thus, the rotation of the second-stage gear 63 is decelerated and transmitted to the output gear 64. As described above, the rotation of the motor gear 61 is decelerated and transmitted to the first-stage gear 62, and the rotation of the first-stage gear 62 is decelerated and transmitted to the second-stage gear 63. Thus, the transmission mechanism 60 decelerates the rotation of the motor shaft 23 and transmits it to the output shaft 66.

[0060] The output shaft 66 outputs the driving force of the electric actuator 1. The output shaft 66 is substantially cylindrical and extends axially with the output axis J4 as the center. The output shaft 66 can rotate around the output axis J4. The output shaft 66 passes through the fourth substrate hole 80d, the first-stage gear 62, and the inside of the output gear 64 in the axial direction. The upper end of the output shaft 66 is arranged inside the second bottom wall hole portion 14f. The upper end of the output shaft 66 is supported on the inner circumferential surface of the second bottom wall hole portion 14f via the fourth bearing 94. The output shaft 66 is supported by the inner circumferential surface of the second bottom wall hole portion 14f so as to be rotatable around the output axis J4. The lower part of the output shaft 66 passes through the output hole portion 18f in the axial direction and protrudes to the outside of the housing 10. The part of the output shaft 66 that protrudes to the outside of the housing 10 is connected to a driven component not shown. Thus, the electric actuator 1 can drive the driven component.

[0061] Next, the assembly process Pf of the electric actuator 1 of this embodiment will be described. The assembly process Pf is a part of the manufacturing process of the electric actuator 1. In the assembly process Pf, the rotor 20 and the cover member 17 are respectively assembled to the motor housing 12. Figure 3As shown, the assembly process Pf includes the following processes: a first process P01, inserting the rotor 20 into the motor housing 12 through the opening 12a, allowing the second support portion 14a to support the lower part of the motor shaft 23 and allowing the motor shaft 23 to pass through the through hole 14c; a second process P02, fixing the part of the motor shaft 23 protruding downward from the bottom wall portion 14 through the through hole 14c to the shaft fixing jig 96; a third process P03, moving the cover member 17 from the upper side to the lower side of the motor housing 12, allowing the upper part of the motor shaft 23 to be supported by the first support portion 17a; and a fourth process P04, rotating the cover member 17 around the central axis J1, and rotating and welding the lower surface of the cover member 17 to the cover fixing portion 13b. In addition, in this specification, "operators, etc." include operators and assembly devices, etc. who perform various operations of the assembly process Pf. Each operation may be performed only by an operator, only by an assembling device, or by an operator and an assembling device.

[0062] like Figure 4 As shown, in the first step P01, the operator first inserts the stator 30 into the motor housing 12 through the opening 12a of the housing body 11 fixed to a jig (not shown), and installs the stator 30 in the motor housing 12. At this time, the core back 31a of the stator core 31 is fixed to the inner peripheral surface of the peripheral wall 13, and the surface of the core back 31a facing downward is in contact with the step surface 13a in the axial direction. In addition, the coil lead wire 35b passes through the first bottom wall hole 14e of the bottom wall 14 in the axial direction.

[0063] Next, the operator moves the rotor 20 to which the first bearing 91 and the second bearing 92 are mounted from the upper side to the lower side of the housing body 11, and inserts the rotor 20 into the motor housing 12 through the opening 12a. Figure 5 As shown, the operator moves the rotor 20 further downward, inserts the second bearing 92 into the second support portion 14a, and mounts the second bearing 92 on the inner circumferential surface of the second support portion 14a. Thus, the operator supports the portion of the motor shaft 23 that is lower than the stator 30, that is, on the other axial side (-Z side) via the second bearing 92 on the second support portion 14a. That is, the operator supports the lower portion of the motor shaft 23 on the second support portion 14a. In addition, the operator passes the motor shaft 23 through the interior of the second support portion 14a and the through hole 14c, respectively. Thus, the lower portion of the motor shaft 23 protrudes downward from the bottom wall portion 14. When the motor shaft 23 is supported by the second support portion 14a and the motor shaft 23 is passed through the through hole 14c, the first step P01 is completed.

[0064] In the second step P02, the operator or the like fixes the portion of the motor shaft 23 that protrudes downward from the bottom wall portion 14, that is, toward the other axial side (-Z side) through the through hole 14c to the shaft fixing jig 96. In the present embodiment, the portion of the motor shaft 23 that protrudes downward from the bottom wall portion 14 is inserted into the shaft fixing hole 96a provided in the shaft fixing jig 96 and fixed to the inner peripheral surface of the shaft fixing hole 96a. The shaft fixing hole 96a is a circular hole that is recessed downward from the upper surface of the shaft fixing jig 96. Although not shown in the figure, the center axis of the shaft fixing hole 96a overlaps with the housing axis J2 that is the center axis of the motor housing 12. As a result, the center axis J1 that is the center axis of the motor shaft 23 overlaps with the housing axis J2, so that the coaxiality of the motor shaft 23 and the motor housing 12 can be improved. When the portion of the motor shaft 23 that protrudes downward from the bottom wall portion 14 is fixed to the shaft fixing jig 96, the second step P02 is completed.

[0065] In the third step P03, the operator moves the cover member 17 from the upper side to the lower side of the motor housing 12. Figure 6 As shown, the upper portion of the motor shaft 23 is inserted into the interior of the first support portion 17a. Thus, the operator supports the portion of the motor shaft 23 that is above the stator 30 on the first support portion 17a via the first bearing 91. That is, the operator supports the upper portion of the motor shaft 23 on the first support portion 17a. Thus, the center axis J1 of the motor shaft 23 overlaps with the cover axis J3 of the cover component 17, thereby improving the coaxiality of the motor shaft 23 and the cover component 17. At this time, the radial outer edge of the surface of the cover component 17 facing the lower side is in axial contact with the cover fixing portion 13b. In addition, the cover annular portion 17d is arranged on the radial outside of the cover fixing portion 13b. When the upper portion of the motor shaft 23 is supported on the first support portion 17a, the third step P03 is completed.

[0066] In the fourth step P04, the operator rotates the cover component 17 around the central axis J1 to rotationally weld the cover component 17 and the cover fixing portion 13b. In the present embodiment, the cover component 17 is pressed against the cover fixing portion 13b by a cover rotating jig (not shown) and is rotated around the central axis J1. As described above, the radial outer edge of the downward surface of the cover component 17 is in axial contact with the cover fixing portion 13b, so friction heat is generated between the radial outer edge of the downward surface of the cover component 17 and the cover fixing portion 13b. In addition, as described above, the motor housing 12 and the cover component 17 are respectively made of resin, so the radial outer edge of the downward surface of the cover component 17 and the cover fixing portion 13b are melted by the friction heat. Next, the operator stops the rotation of the cover component 17. Thus, when Figure 2When the temperature of the cover welding portion 17b and the cover fixing portion 13b shown in the figure decreases and solidifies, the cover welding portion 17b and the cover fixing portion 13b are joined by welding. At this time, the cover welding portion 17b and the cover fixing portion 13b are joined over the entire circumference. When the cover member 17 and the cover fixing portion 13b are rotationally welded, the fourth step P04 is completed. When the fourth step P04 is completed, the rotor 20 and the cover member 17 are respectively assembled to the motor housing 12, and the assembly step Pf of the electric actuator 1 is completed.

[0067] According to the present embodiment, the motor housing 12 and the cover member 17 are made of resin, and the cover member 17 has a first support portion 17a that supports a portion of the motor shaft 23 located above the stator 30, that is, on one axial side (+Z side), and the cover member 17 is in the shape of a disk centered on the central axis J1. The motor housing 12 has a bottom wall portion 14 that is provided with a second support portion 14a that supports a portion of the motor shaft 23 located below the stator 30, that is, on the other axial side (-Z side), and a through hole 14c through which the motor shaft 23 passes in the axial direction, and the bottom wall portion 14 extends in a direction intersecting the axial direction; and a cover fixing portion 13b that is annular, contacts the surface of the cover member 17 facing downward in the axial direction, and surrounds the central axis J1. The cover member 17 and the cover fixing portion 13b are joined to each other over the entire circumference in the circumferential direction. Therefore, the lower portion of the motor shaft 23 passes through the through hole 14c in the axial direction, so in the second step P02, the lower portion of the motor shaft 23 can be fixed to the shaft fixing jig 96 from the outside of the motor housing 12. As a result, the motor shaft 23 can be supported by the motor housing 12 in a state where the coaxiality between the motor housing 12 and the motor shaft 23 is improved. In addition, the cover member 17 has the first support portion 17a that supports the upper portion of the motor shaft 23, so the radial position of the first support portion 17a is adjusted according to the motor shaft 23 fixed by the shaft fixing jig 96, thereby improving the coaxiality between the cover member 17 and the motor shaft 23. Therefore, in the fourth step P04, the cover member 17 can be rotated around the central axis J1 with high precision, so that the cover member 17 can be joined to the motor housing 12 by rotational welding while improving the coaxiality between the cover member 17 and the motor shaft 23. Thus, the coaxiality between the motor shaft 23 and the motor housing 12 and the cover member 17 can be improved, and thus the coaxiality between the motor shaft 23 and the housing 10 can be improved. In addition, since the lower portion of the motor shaft 23 only needs to be fixed by the shaft fixing jig 96, it is not necessary to provide a hole in the cover member 17 for pressing the upper portion of the motor shaft 23 by a jig or the like. Therefore, compared with the case where the motor housing 12 and the cover member 17 are assembled to the motor shaft 23 in a state where both ends of the motor shaft 23 in the axial direction are fixed by a jig or the like, it is not necessary to provide a hole in the cover member 17 for passing the jig or the like. Therefore, in the present embodiment, it is not necessary to provide a cap or the like for closing the hole provided in the cover member 17 in order to improve the airtightness of the electric actuator 1. Therefore, it is possible to suppress an increase in the number of components of the electric actuator 1. Therefore, it is possible to suppress an increase in the number of components of the electric actuator 1 while improving the coaxiality between the motor shaft 23 and the housing 10.

[0068] In the present embodiment, the cover member 17 and the cover fixing portion 13 b are joined to each other over the entire circumference, so that the cover member 17 and the motor case 12 can be sealed over the entire circumference. Therefore, the airtightness of the electric actuator 1 can be improved.

[0069] In addition, in this embodiment, the motor case 12 and the cover member 17 are each made of resin. Therefore, compared with the case where the motor case 12 and the cover member 17 are each made of metal, the increase in manufacturing cost of the electric actuator 1 can be suppressed and the weight of the electric actuator 1 can be reduced.

[0070] According to the present embodiment, the cover member 17 has the cover welding portion 17b joined to the cover fixing portion 13b by welding. Therefore, the cover member 17 and the motor housing 12 can be appropriately sealed, so the airtightness of the electric actuator 1 can be more appropriately improved. In addition, there is no need to separately provide a sealing member such as an O-ring for sealing between the cover member 17 and the motor housing 12, so the number of components of the electric actuator 1 can be suppressed from increasing.

[0071] According to the present embodiment, the first support portion 17a supports the portion of the motor shaft 23 located above the stator 30, that is, on one axial side (+Z side), via the first bearing 91, and the second support portion 14a supports the portion of the motor shaft 23 located below the stator 30, that is, on the other axial side (-Z side), via the second bearing 92. Therefore, when the electric actuator 1 is in operation, when the motor shaft 23 rotates around the central axis J1, it is possible to suppress the increase in the friction force between the motor shaft 23 and the cover member 17 and the friction force between the motor shaft 23 and the motor housing 12. Therefore, the output efficiency of the electric actuator 1 can be improved, and the vibration and noise when the electric actuator 1 is in operation can be suppressed.

[0072] According to the present embodiment, the electric actuator 1 has a transmission mechanism 60 that transmits the rotation of the motor shaft 23 to the output shaft 66, and the transmission mechanism 60 is connected to a portion of the motor shaft 23 that is located below the bottom wall portion 14, that is, at the other axial side (-Z side). As a result, the portion of the motor shaft 23 that is located below the bottom wall portion 14, that is, the portion fixed to the shaft fixing jig 96 in the second step P02, can be used as a portion connected to the transmission mechanism 60. Therefore, compared with the case where the transmission mechanism 60 is connected to the upper portion of the motor shaft 23, the increase in the axial dimension of the motor shaft 23 can be suppressed. Therefore, the electric actuator 1 can be suppressed from being enlarged in the axial direction.

[0073] In addition, in the present embodiment, as described above, the transmission mechanism 60 decelerates the rotation of the motor shaft 23 and transmits it to the output shaft 66. Therefore, the transmission mechanism 60 can increase the rotation torque of the output shaft 66 relative to the rotation torque of the motor shaft 23, so that the driven components connected to the output shaft 66 can be smoothly driven.

[0074] According to the present embodiment, the manufacturing method of the electric actuator 1 includes an assembly step Pf of assembling the rotor 20 and the cover member 17 to the motor housing 12, respectively. The assembly step Pf includes the following steps: a first step P01 of inserting the rotor 20 into the motor housing 12 through the opening 12a, so that the second support portion 14a supports the lower portion of the motor shaft 23, that is, the portion on the other axial side (-Z side), and the motor shaft 23 passes through the through hole 14c; a second step P02 of inserting the motor shaft 23 into the motor housing 12 through the opening 12a. The portion of the motor shaft 23 protruding downward from the bottom wall 14 through the through hole 14c is fixed to the shaft fixing jig 96; in the third step P03, the cover member 17 is moved downward from the upper side of the motor housing 12, that is, from one axial side (+Z side), so that the upper part of the motor shaft 23 is supported by the first supporting portion 17a; and in the fourth step P04, the cover member 17 is rotated around the central axis J1, and the downward surface of the cover member 17 is rotationally welded to the cover fixing portion 13b. Therefore, in the second step P02, the portion of the motor shaft 23 protruding downward from the bottom wall 14 can be fixed to the shaft fixing jig 96 from the outside of the motor housing 12, so that the motor shaft 23 can be assembled to the motor housing 12 in a state where the coaxiality of the motor shaft 23 and the motor housing 12 is improved. In addition, in the fourth step P04, the cover member 17 is joined to the motor housing 12 by rotational welding in which the cover member 17 is joined to the motor housing 12 while rotating the cover member 17 around the central axis J1, so that the coaxiality between the motor shaft 23 and the cover member 17 can be improved. As a result, the coaxiality between the motor shaft 23 and the motor housing 12 and the cover member 17 can be improved. That is, the coaxiality between the motor shaft 23 and the housing 10 can be improved. In addition, as described above, compared with the case where the motor housing 12 and the cover member 17 are fixed to the motor shaft 23 in a state where both ends of the motor shaft 23 in the axial direction are fixed by a jig or the like, it is not necessary to provide a hole for the jig or the like to pass through the motor housing 12 and the cover member 17, and thus it is not necessary to have a cap or the like to close the hole. Therefore, it is possible to improve the coaxiality between the motor shaft 23 and the housing 10 while suppressing an increase in the number of components of the electric actuator 1.

[0075] In addition, in the present embodiment, since the cover welding portion 17b and the cover fixing portion 13b are joined by spin welding in the fourth step P04, it is easy to reduce the circumferential deviation of the friction heat generated by the friction between the cover welding portion 17b and the cover fixing portion 13b. Therefore, for example, compared with the case where the cover member 17 and the cover fixing portion 13b are joined by laser welding, it is easy to reduce the deviation of the joining strength in the circumferential direction. Therefore, the airtightness of the electric actuator 1 can be improved more appropriately.

[0076] In addition, in the present embodiment, in the fourth step P04, the upper side of the motor shaft 23 is supported by the first support portion 17a, and the cover member 17 is rotated about the central axis J1 to rotationally weld the cover member 17 and the cover fixing portion 13b. Therefore, even if there is looseness between the cover annular portion 17d of the cover member 17 and the cover fixing portion 13b, the coaxiality of the motor shaft 23 and the cover member 17 can be improved.

[0077] In addition, in the present embodiment, the coaxiality between the motor shaft 23, the motor housing 12, and the cover member 17 can be improved, so that when the electric actuator 1 is in operation, the motor shaft 23 can be smoothly rotated around the central axis J1. Therefore, the output efficiency of the electric actuator 1 can be improved, and the increase in vibration and noise when the electric actuator 1 is in operation can be suppressed.

[0078] According to the present embodiment, the cover fixing portion 13b is located on the upper side of the motor housing 12, that is, at the end on one axial side (+Z side). Therefore, in the fourth step P04, when the cover component 17 is rotated around the central axis J1, it is easy to press the cover component 17 against the cover fixing portion 13b in the axial direction. As a result, it is easy to increase the amount of frictional heat generated by the friction between the cover welding portion 17b and the cover fixing portion 13b, and it is easy to reduce the deviation of the amount of frictional heat in the circumferential direction. Therefore, it is easy to more appropriately reduce the deviation of the bonding strength between the cover welding portion 17b and the cover fixing portion 13b in the circumferential direction. Therefore, the airtightness of the electric actuator 1 can be more appropriately improved.

[0079] According to the present embodiment, in the first step P01, the portion of the motor shaft 23 on the lower side of the stator 30, that is, on the other side (-Z side) in the axial direction, is supported by the second support portion 14a via the second bearing 92, and in the third step P03, the portion of the motor shaft 23 on the upper side of the stator 30, that is, on the one side (+Z side) in the axial direction, is supported by the first support portion 17a via the first bearing 91. Therefore, in the fourth step P04, when the cover member 17 is rotated around the central axis J1 and the cover welding portion 17b and the cover fixing portion 13b are rotationally welded, it is possible to suppress the increase in the friction force between the motor shaft 23 and the first support portion 17a and the friction force between the motor shaft 23 and the second support portion 14a. Therefore, in the fourth step P04, it is easy to suppress the positional variation of the motor shaft 23, so that the coaxiality of the motor shaft 23 and the cover member 17 can be more appropriately improved.

[0080] The embodiments of the present invention are described above, but the various structures and their combinations in the embodiments are only examples, and addition, omission, substitution and other changes of structures can be made within the scope of the present invention.

[0081] The cover welding part and the cover fixing part can be joined by other welding methods such as laser welding and ultrasonic welding. In this case, the coaxiality of the motor shaft and the cover component can also be improved by welding the cover welding part and the cover fixing part in a state where the motor shaft is supported on the first supporting part of the cover component and the coaxiality of the motor shaft and the cover component is improved.

[0082] In addition, at least one of the first bearing and the second bearing may not be provided. When the first bearing is not provided, the upper portion of the motor shaft is directly supported by the first support portion, and when the second bearing is not provided, the lower portion of the motor shaft is directly supported by the second support portion. However, when the cover member and the motor housing are joined by rotational welding, in order to suppress the increase in friction between the motor shaft and the cover member, it is preferred that the first support portion supports the motor shaft via the first bearing.

[0083] 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. For example, the motor shaft and the motor gear may be part of the same single component, and the output shaft and the output gear may be part of the same single component. In addition, the transmission mechanism may not have the first-stage gear and the second-stage gear. In this case, the motor gear is directly connected to the output gear.

[0084] The application of the electric actuator of the present invention is not particularly limited. The electric actuator can be mounted on an actuator device of a shift-by-wire type that is driven according to the shift operation of the driver. In addition, the electric actuator can be mounted on equipment other than the vehicle. In addition, the various structures described above in this specification can be appropriately combined within the range that they do not contradict each other.

[0085] In addition, the present technology can adopt the following structures.

[0086] (1) An electric actuator, comprising: a rotor having a motor shaft rotatable about a central axis; a stator disposed radially outside the rotor; a motor housing having an opening portion opened on one axial side, the motor housing accommodating the rotor and the stator therein; and a cover member closing the opening portion, the motor housing and the cover member being made of resin, the cover member having a first support portion supporting a portion of the motor shaft located on one axial side of the stator, and the cover member being in the shape of a disk centered on the central axis, the motor housing having a bottom wall portion provided with a second support portion supporting a portion of the motor shaft located on the other axial side of the stator and a through hole through which the motor shaft passes in the axial direction, the bottom wall portion extending in a direction intersecting the axial direction; and a cover fixing portion in an annular shape surrounding the central axis, contacting in the axial direction with a surface of the cover member facing the other axial side, the cover member and the cover fixing portion being engaged with each other over the entire circumference.

[0087] (2) The electric actuator according to (1), wherein the cover member has a cover welding portion joined to the cover fixing portion by welding.

[0088] (3) An electric actuator according to (1) or (2), wherein the first supporting portion supports a portion of the motor shaft located on one axial side of the stator via a first bearing, and the second supporting portion supports a portion of the motor shaft located on the other axial side of the stator via a second bearing.

[0089] (4) An electric actuator according to any one of (1) to (3), wherein the electric actuator has a transmission mechanism for transmitting the rotation of the motor shaft to the output shaft, and the transmission mechanism is connected to a portion of the motor shaft located on the other axial side of the bottom wall portion.

[0090] (5) A method for manufacturing an electric actuator, the electric actuator comprising: a rotor having a motor shaft that can rotate around a central axis; a stator that is arranged radially outside the rotor; a motor housing that has an opening portion that opens on one axial side, the motor housing internally accommodating the rotor and the stator; and a cover component that closes the opening portion, wherein the method for manufacturing the electric actuator comprises an assembling step of assembling the rotor and the cover component to the motor housing, respectively, the motor housing and the cover component are respectively made of resin, the cover component has a first support portion that supports a portion of the motor shaft that is located axially to one side of the stator, and the cover component is in the shape of a circular plate centered on the central axis, and the motor housing has: a bottom wall portion that is provided with a second support portion and a cover portion through which the motor shaft passes in the axial direction The through hole passing through the motor housing, the bottom wall portion extending in a direction intersecting the axial direction; and a cover fixing portion, which is annular and surrounds the central axis, the assembling process comprises the following processes: a first process, inserting the rotor into the interior of the motor housing through the opening portion, so that the second supporting portion supports the portion of the motor shaft on the other axial side and the motor shaft passes through the through hole; a second process, fixing the portion of the motor shaft that protrudes to the other axial side than the bottom wall portion through the through hole to an axis fixing fixture; a third process, moving the cover component from one axial side to the other axial side of the motor housing, so that the portion of the motor shaft on one axial side is supported by the first supporting portion; and a fourth process, rotating the cover component around the central axis, and rotationally welding the surface of the cover component facing the other axial side to the cover fixing portion.

[0091] (6) The method for manufacturing an electric actuator according to (5), wherein the cover fixing portion is located at an end portion on one axial side of the motor case.

[0092] (7) A method for manufacturing an electric actuator according to (5) or (6), wherein, in the first step, a portion of the motor shaft that is on the other axial side than the stator is supported by the second supporting portion via a second bearing, and in the third step, a portion of the motor shaft that is on the one axial side than the stator is supported by the first supporting portion via a first bearing.

Claims

1. An electric actuator, comprising: A rotor having a motor shaft rotatable about a central axis; a stator, which is arranged radially outside the rotor; a motor housing having an opening portion opened on one axial side, the motor housing accommodating the rotor and the stator in the interior; and a cover member that closes the opening, The motor housing and the cover member are respectively made of resin. The cover member has a first support portion that supports a portion of the motor shaft that is located axially closer to one side than the stator, and the cover member is in a disk shape centered on the central axis. The motor housing has: a bottom wall portion having a second support portion for supporting a portion of the motor shaft on the other axial side of the stator and a through hole for the motor shaft to pass through in the axial direction, the bottom wall portion extending in a direction intersecting the axial direction; and a cover fixing portion which is in an annular shape surrounding the central axis and is in axial contact with a surface of the cover member which faces the other axial side. The cover member and the cover fixing portion are joined to each other over the entire circumference.

2. The electric actuator according to claim 1, wherein: The cover member includes a cover welding portion joined to the cover fixing portion by welding.

3. The electric actuator according to claim 1 or 2, wherein: The first support portion supports a portion of the motor shaft located on the axial side of the stator via a first bearing. The second support portion supports a portion of the motor shaft located on the other axial side of the stator via a second bearing.

4. The electric actuator according to claim 1 or 2, wherein: The electric actuator has a transmission mechanism for transmitting the rotation of the motor shaft to the output shaft. The transmission mechanism is connected to a portion of the motor shaft located on the other side in the axial direction relative to the bottom wall portion.

5. A method for manufacturing an electric actuator, the electric actuator comprising: a rotor having a motor shaft rotatable about a central axis; a stator disposed radially outside the rotor; a motor housing having an opening portion opened on one axial side, the motor housing housing the rotor and the stator; and a cover member closing the opening portion. in, The method for manufacturing the electric actuator includes an assembling step of assembling the rotor and the cover member to the motor housing, respectively. The motor housing and the cover member are respectively made of resin. The cover member has a first support portion that supports a portion of the motor shaft that is located axially closer to one side than the stator, and the cover member is in a disk shape centered on the central axis. The motor housing has: a bottom wall portion having a second support portion and a through hole through which the motor shaft passes in the axial direction, the bottom wall portion extending in a direction intersecting the axial direction; and a cover fixing portion, which is in a ring shape surrounding the central axis, The assembly process has the following steps: In a first step, the rotor is inserted into the motor housing through the opening, the second support portion supports the other axial side portion of the motor shaft, and the motor shaft passes through the through hole; In a second step, a portion of the motor shaft that protrudes from the bottom wall portion in the axial direction to the other side through the through hole is fixed to a shaft fixing jig; a third step of moving the cover member from one axial side to the other axial side of the motor housing so that a portion of the motor shaft on one axial side is supported by the first support portion; and In a fourth step, the cover member is rotated about the central axis to rotationally weld the surface of the cover member facing the other side in the axial direction to the cover fixing portion.

6. The method for manufacturing an electric actuator according to claim 5, wherein: The cover fixing portion is located at an end portion on one axial side of the motor housing.

7. The method for manufacturing an electric actuator according to claim 5 or 6, wherein: In the first step, a portion of the motor shaft that is closer to the other side in the axial direction than the stator is supported by the second support portion via a second bearing. In the third step, a portion of the motor shaft located on the axial side relative to the stator is supported by the first support portion via a first bearing.

Images