JP7625874B2 - Electric actuator and method for manufacturing electric actuator - Google Patents

Description

The present invention relates to an electric actuator and a method for manufacturing an electric actuator.

Electric actuators equipped with reduction gears are known. For example, Patent Document 1 describes a reduction gear having a sun gear provided via a bearing on the outer periphery of the eccentric part of the input shaft, and a ring gear that meshes with the sun gear.

JP 2016-109226 A

In the above-mentioned reducer, for example, the ring gear is fixed by being pressed into the case. However, simply pressing the ring gear into the case may cause problems such as the ring gear coming out of the case or shifting relative to the case.

In view of the above circumstances, one of the objects of the present invention is to provide an electric actuator having a structure that can improve the fixing strength of the internal gear to the case. Another object of the present invention is to provide a manufacturing method for an electric actuator that can improve the fixing strength of the internal gear to the case.

One aspect of the electric actuator of the present invention includes a motor having a motor shaft rotatable about a central axis extending in the axial direction, a reduction mechanism having an external gear connected to the motor shaft and an annular internal gear surrounding the radial outside of the external gear, a case that houses the motor and the reduction mechanism, and a fixing member that fixes the internal gear to the case. The case has a bottom wall that supports the internal gear from one axial side, and a peripheral wall that is located radially outside the internal gear and surrounds the internal gear. The fixing member has an annular portion that surrounds the internal gear radially between the internal gear and the peripheral wall. The annular portion is in contact with an outer circumferential surface of the internal gear and an inner circumferential surface of the peripheral wall. The hardness of the material constituting the fixed member is lower than the hardness of the material constituting the internal gear and the hardness of the material constituting the peripheral wall portion, a first recess recessed radially outward is provided on an inner peripheral surface of the peripheral wall portion, the fixed member has an insertion portion inserted into the first recess, and the insertion portion is in contact with an inner surface of the first recess.
Electric actuator.
Moreover, one aspect of the electric actuator of the present invention is an electric actuator comprising: a motor having a motor shaft rotatable around a central axis extending in the axial direction; a reduction mechanism having an external gear connected to the motor shaft and an annular internal gear surrounding the radial outside of the external gear; a case that accommodates the motor and the reduction mechanism inside; and a fixing member that fixes the internal gear to the case, wherein the case has a bottom wall portion that supports the internal gear from one axial side, and a peripheral wall portion that is located radially outside the internal gear and surrounds the internal gear, the fixing member has an annular portion that surrounds the internal gear radially between the internal gear and the peripheral wall portion, the annular portion contacts an outer peripheral surface of the internal gear and an inner peripheral surface of the peripheral wall portion, the hardness of a material constituting the fixing member is smaller than the hardness of a material constituting the internal gear and the hardness of a material constituting the peripheral wall portion, the internal gear has a second recess on its outer peripheral surface, and the fixing member has a protrusion that is located inside the second recess.
Furthermore, one aspect of the electric actuator of the present invention includes a motor having a motor shaft rotatable about a central axis extending in the axial direction, a reduction mechanism having an external gear connected to the motor shaft and an annular internal gear surrounding the radial outside of the external gear, a case that houses the motor and the reduction mechanism, and a fixing member that fixes the internal gear to the case, the case having a bottom wall portion that supports the internal gear from one axial side, an annular portion surrounding the internal gear and located radially outside the internal gear, the fixed member having an annular portion surrounding the internal gear radially between the internal gear and the circumferential wall portion, the annular portion contacting an outer circumferential surface of the internal gear and an inner circumferential surface of the circumferential wall portion, the hardness of a material constituting the fixed member being less than a hardness of a material constituting the internal gear and a hardness of a material constituting the circumferential wall portion, the inner circumferential surface of the circumferential wall portion having a first recess recessed radially outward, a portion of the fixed member contacting an inner surface of the first recess, the internal gear having a second recess on its outer circumferential surface, and a portion of the fixed member located inside the second recess.

One aspect of the manufacturing method of the electric actuator of the present invention is a manufacturing method of an electric actuator including a motor having a motor shaft rotatable around a central axis extending in the axial direction, a reduction mechanism having an external gear connected to the motor shaft and an annular internal gear surrounding the radial outside of the external gear, and a case accommodating the motor and the reduction mechanism therein, the manufacturing method including a fixing step of fixing the internal gear to the case using a fixing member having an annular portion, the case having a bottom wall portion supporting the internal gear from one axial side, and a peripheral wall portion positioned radially outside the internal gear and surrounding the internal gear, the hardness of the fixing member being smaller than the hardness of the internal gear and the hardness of the peripheral wall portion, the fixing step including
A manufacturing method for an electric actuator includes a deformation process in which the fixed member, with the annular portion disposed radially between the internal gear and the circumferential wall portion, is pressed against the bottom wall portion from the other axial side toward the one axial side, and deformed, wherein in the deformation process, the annular portion is deformed and pressed against the outer peripheral surface of the internal gear and the inner peripheral surface of the circumferential wall portion, and a first recess is provided on the inner peripheral surface of the circumferential wall portion, the first recess being recessed radially outward, and in the deformation process, a part of the fixed member is deformed and enters the first recess .

According to one aspect of the present invention, the fixing strength of the internal gear to the case in an electric actuator can be improved.

FIG. 1 is a cross-sectional view showing an electric actuator according to an embodiment. FIG. 2 is a cross-sectional view showing a part of the electric actuator of the embodiment, taken along line II-II in FIG. FIG. 3 is a cross-sectional view showing a part of a case, a part of an internal gear, and a part of a fixing member according to one embodiment. FIG. 4 is a perspective view showing a fixing member according to one embodiment. FIG. 5 is a flow chart showing an example of a procedure of the fixing step according to one embodiment. FIG. 6 is a cross-sectional view showing a part of the procedure of the fixing step of one embodiment.

In each figure, the Z-axis direction is the up-down direction with the side toward which the arrow points (+Z side) being the top and the opposite side to the side toward which the arrow points (-Z side) being the bottom. The axial direction of the central axis J1, as appropriately shown in each figure, is parallel to the Z-axis direction, i.e., the up-down direction. In the following explanation, unless otherwise specified, the direction parallel to the axial direction of the central axis J1 will simply be referred to as the "axial direction." Furthermore, unless otherwise specified, the radial direction centered on the central axis J1 will simply be referred to as the "radial direction," and the circumferential direction centered on the central axis J1 will simply be referred to as the "circumferential direction."

In this embodiment, the upper side corresponds to the other axial side, and the lower side corresponds to one axial side. Note that the terms upper side and lower side are names used simply to describe the relative positional relationships of the various parts, and the actual positional relationships may be other than those indicated by these names.

The electric actuator 10 of this embodiment shown in Figures 1 and 2 is, for example, an electric actuator mounted on a vehicle. As shown in Figure 1, the electric actuator 10 includes a case 11, a motor 20 having a motor shaft 21 that can rotate around a central axis J1 extending in the axial direction, a first bearing 51, a second bearing 52, a third bearing 53, a bush 54, a reduction mechanism 30, an output section 40, a preload member 60, a circuit board 70, a first rotation sensor 71, an attachment member 72, a first sensor magnet 73, a second sensor magnet 74, a second rotation sensor (not shown), and a fixing member 80.

The case 11 houses the motor 20 and the reduction mechanism 30 inside. The case 11 has a motor case 12 that houses the motor 20 inside, and a reduction mechanism case 13 that houses the reduction mechanism 30 inside. In this embodiment, the motor case 12 and the reduction mechanism case 13 are each made by die casting. The material that constitutes the motor case 12 and the material that constitutes the reduction mechanism case 13 are, for example, an alloy containing aluminum. The motor case 12 has a case tube portion 12a, an annular plate portion 12b, an upper cover portion 12c, a bearing holding portion 12d, and a circuit board housing portion 12g.

The case tube portion 12a is cylindrical and extends in the axial direction around the central axis J1. The case tube portion 12a is open on both sides in the axial direction. The case tube portion 12a surrounds the radial outside of the motor 20. The annular plate portion 12b is annular plate-shaped and spreads radially inward from the inner peripheral surface of the case tube portion 12a. The annular plate portion 12b covers the upper side of the stator 23 of the motor 20, which will be described later. The radial inner edge of the annular plate portion 12b is curved downward.

The bearing retaining portion 12d is provided on the radial inner edge of the annular plate portion 12b. The bearing retaining portion 12d retains the third bearing 53. The bearing retaining portion 12d has a retaining portion main body 12e and a support wall portion 12f. The retaining portion main body 12e is cylindrical and extends upward from the radial inner edge of the annular plate portion 12b. The support wall portion 12f protrudes radially inward from the upper end of the retaining portion main body 12e. Although not shown, the support wall portion 12f is annular and extends circumferentially.

The circuit board accommodating section 12g is a section that accommodates the circuit board 70. The circuit board accommodating section 12g is configured radially inward of the upper part of the case cylindrical section 12a. The bottom surface of the circuit board accommodating section 12g is the upper surface of the annular plate section 12b. The circuit board accommodating section 12g is open on the upper side. The upper cover section 12c is a plate-shaped cover that closes the upper end opening of the circuit board accommodating section 12g.

The reduction mechanism case 13 is fixed to the underside of the motor case 12. The reduction mechanism case 13 has a lid portion 13a, a cylindrical portion 13b, and a protruding cylindrical portion 13c. The lid portion 13a is an annular plate centered on the central axis J1. The lid portion 13a covers the underside of the reduction mechanism 30.

The tubular portion 13b is cylindrical and protrudes upward from the radial outer edge of the lid portion 13a. The tubular portion 13b is open at the top. The upper end of the tubular portion 13b is fixed in contact with the lower end of the case tubular portion 12a. The tubular portion 13b has a bottom wall portion 13j and a peripheral wall portion 13k. In other words, the case 11 has the bottom wall portion 13j and the peripheral wall portion 13k.

In this embodiment, the bottom wall portion 13j is the upper end of the radially inner portion of the cylindrical portion 13b. The bottom wall portion 13j is annular about the central axis J1. The bottom wall portion 13j supports the internal gear 32, which will be described later, from below. As shown in FIG. 3, the bottom wall portion 13j has an annular step portion 13g surrounding the central axis J1 on the upper surface. In this embodiment, the step portion 13g is annular about the central axis J1. The step portion 13g is a step that is recessed downward when tracing the upper surface of the bottom wall portion 13j from the radial outside to the radial inside. In other words, the inner bottom surface portion 13i, which is located radially inward from the step portion 13g on the upper surface of the bottom wall portion 13j, is located lower than the outer bottom surface portion 13m, which is located radially outward from the step portion 13g on the upper surface of the bottom wall portion 13j. The inner bottom surface portion 13i and the outer bottom surface portion 13m are flat surfaces that face upward and are perpendicular to the axial direction. The step portion 13g is located in the radial center of the upper surface of the bottom wall portion 13j.

As shown in FIG. 1, the peripheral wall portion 13k protrudes upward from the radial outer peripheral edge portion of the bottom wall portion 13j. The peripheral wall portion 13k is annular about the central axis J1. The peripheral wall portion 13k is located radially outside the internal gear 32 described later and surrounds the internal gear 32. As shown in FIG. 3, in this embodiment, the inner peripheral surface of the peripheral wall portion 13k is provided with a first recess 13f recessed radially outward. The first recess 13f is provided at the lower end of the inner peripheral surface of the peripheral wall portion 13k. As shown in FIG. 2, in this embodiment, the first recess 13f is annular and surrounds the internal gear 32. More specifically, the first recess 13f is annular about the central axis J1. As shown in FIG. 3, the axial dimension of the first recess 13f decreases as it goes radially outward.

In this embodiment, the cross-sectional shape of the first recess 13f perpendicular to the circumferential direction is a triangle with an acute apex on the radially outer side. The lower surface of the inner surface of the first recess 13f is a flat surface perpendicular to the axial direction and is connected to the radially outer side of the outer bottom surface portion 13m without any steps. The upper surface of the inner surface of the first recess 13f is a tapered surface that is positioned downward as it moves radially outward.

As shown in FIG. 1, a recess 13e is formed at the radially inner portion of the upper end of the cylindrical portion 13b by the bottom wall portion 13j and the peripheral wall portion 13k. The recess 13e is open radially inward. The recess 13e is annular and centered on the central axis J1.

The protruding tube portion 13c is cylindrical and protrudes from the radial inner edge of the lid portion 13a on both axial sides. The protruding tube portion 13c is open on both axial sides. The upper end of the protruding tube portion 13c is located lower than the upper end of the tube portion 13b. An O-ring 61 is attached to the outer circumferential surface at the lower end of the protruding tube portion 13c. A cylindrical bushing 54 extending in the axial direction is arranged inside the protruding tube portion 13c.

The motor 20 is housed in a portion of the case 11 below the annular plate portion 12b. The motor 20 has a rotor 22 and a stator 23. The rotor 22 has a motor shaft 21 and a rotor body 22a. The motor shaft 21 is supported by a first bearing 51 and a third bearing 53 so as to be rotatable around the central axis J1. The motor shaft 21 has a first shaft portion 21a, a second shaft portion 21b, a third shaft portion 21c, a fourth shaft portion 21d, a fifth shaft portion 21e, a sixth shaft portion 21f, a seventh shaft portion 21g, and an eighth shaft portion 21h. Each shaft portion except for the sixth shaft portion 21f is centered on the central axis J1.

The first shaft portion 21a is the upper end of the motor shaft 21. The first shaft portion 21a protrudes upward from the annular plate portion 12b through the radial inner side of the bearing holding portion 12d. The first shaft portion 21a is the portion of the motor shaft 21 with the smallest outer diameter. The second shaft portion 21b is connected to the lower side of the first shaft portion 21a. The outer diameter of the second shaft portion 21b is larger than the outer diameter of the first shaft portion 21a. The third shaft portion 21c is connected to the lower side of the second shaft portion 21b. The outer diameter of the third shaft portion 21c is larger than the outer diameter of the second shaft portion 21b. As a result, a step portion 21i whose outer diameter increases from the upper side to the lower side is provided between the second shaft portion 21b and the third shaft portion 21c. In other words, the motor shaft 21 has a step portion 21i.

The fourth shaft portion 21d is connected to the lower side of the third shaft portion 21c. The outer diameter of the fourth shaft portion 21d is larger than the outer diameter of the third shaft portion 21c. A balance weight 24 is fixed to the fourth shaft portion 21d. The balance weight 24 is a plate-like member with its plate surface facing the axial direction. The fifth shaft portion 21e is connected to the lower side of the fourth shaft portion 21d. The outer diameter of the fifth shaft portion 21e is larger than the outer diameter of the fourth shaft portion 21d. The fifth shaft portion 21e is the part of the motor shaft 21 with the largest outer diameter. The balance weight 24 is in contact with the upper end of the fifth shaft portion 21e. This allows the balance weight 24 to be positioned axially relative to the motor shaft 21.

The sixth shaft portion 21f is connected to the lower side of the fifth shaft portion 21e. The sixth shaft portion 21f is an eccentric shaft portion centered on an eccentric axis J2 that is eccentric with respect to the central axis J1. The eccentric axis J2 is parallel to the central axis J1 and is located radially outward of the central axis J1. The outer diameter of the sixth shaft portion 21f is smaller than the outer diameter of the fifth shaft portion 21e. In other words, the fifth shaft portion 21e is connected to the upper side of the sixth shaft portion 21f and is a large diameter shaft portion having an outer diameter larger than that of the sixth shaft portion 21f. The outer diameter of the sixth shaft portion 21f is smaller than the outer diameter of the fourth shaft portion 21d and larger than the outer diameter of the third shaft portion 21c.

The seventh shaft portion 21g is connected to the lower side of the sixth shaft portion 21f. The outer diameter of the seventh shaft portion 21g is smaller than the outer diameter of the sixth shaft portion 21f. The eighth shaft portion 21h is connected to the lower side of the seventh shaft portion 21g. The eighth shaft portion 21h is the lower end of the motor shaft 21. The outer diameter of the eighth shaft portion 21h is smaller than the outer diameter of the seventh shaft portion 21g. The seventh shaft portion 21g and the eighth shaft portion 21h are housed inside the housing recess 41a described later.

The rotor body 22a is fixed to the outer peripheral surface of the motor shaft 21. More specifically, the rotor body 22a is fixed to the outer peripheral surface of the third shaft portion 21c. Although not shown in the figure, the rotor body 22a has a rotor core fixed to the outer peripheral surface of the motor shaft 21 and a rotor magnet fixed to the rotor core.

The stator 23 is located radially outside the rotor 22. The stator 23 has a stator core 23a and multiple coils 23b. The stator core 23a is annular and surrounds the radial outside of the rotor 22. The outer peripheral surface of the stator core 23a is fixed to the inner peripheral surface of the case cylindrical portion 12a. The multiple coils 23b are attached to the stator core 23a, for example, via an insulator (not shown).

The first bearing 51, the second bearing 52, and the third bearing 53 are each a rolling bearing having an inner ring and an outer ring located radially outside the inner ring. In this embodiment, the first bearing 51, the second bearing 52, and the third bearing 53 are, for example, ball bearings in which the inner ring and the outer ring are connected via a number of balls.

In this embodiment, the reduction mechanism 30 is disposed radially outward of the lower portion of the motor shaft 21. The reduction mechanism 30 is housed inside the reduction mechanism case 13. The reduction mechanism 30 is disposed axially between the cover portion 13a and the motor 20. The reduction mechanism 30 has an external gear 31, an internal gear 32, a flange portion 42, and a plurality of protrusions 43.

As shown in FIG. 2, the external gear 31 is annular and surrounds the sixth shaft portion 21f, which is an eccentric shaft portion, on the radial outside of the sixth shaft portion 21f. More specifically, the external gear 31 is a substantially annular plate that extends on a plane perpendicular to the axial direction, centered on the eccentric axis J2. A gear portion having a plurality of teeth 31d is provided on the radially outer surface of the external gear 31. The external gear 31 is connected to the sixth shaft portion 21f via the second bearing 52. As a result, the reduction mechanism 30 is connected to the lower part of the motor shaft 21. The second bearing 52 connects the motor shaft 21 and the external gear 31 so that they can rotate relatively around the eccentric axis J2. The external gear 31 is fitted into the outer ring of the second bearing 52 from the radially outer side.

As shown in FIG. 1, the external gear 31 has an external gear body 31a and a contact protrusion 31b. The external gear body 31a is a substantially annular plate-shaped portion fixed to the outer ring of the second bearing 52. The contact protrusion 31b is a portion that protrudes downward from the external gear body 31a. In this embodiment, the contact protrusion 31b protrudes downward from the radial inner edge of the external gear body 31a. Although not shown, the contact protrusion 31b is annular about the eccentric axis J2. The lower surface of the contact protrusion 31b is a flat surface that is perpendicular to the axial direction. The lower surface of the contact protrusion 31b is a machined surface created by, for example, cutting.

The external gear 31 has a plurality of holes 31c recessed upward. The plurality of holes 31c are provided in the external gear main body 31a. In this embodiment, the holes 31c penetrate the external gear 31 in the axial direction. As shown in FIG. 2, the plurality of holes 31c are arranged along the circumferential direction. More specifically, the plurality of holes 31c are arranged at equal intervals around one circumference along the circumferential direction centered on the eccentric axis J2. The holes 31c are, for example, circular when viewed in the axial direction. The inner diameter of the holes 31c is larger than the outer diameter of the protrusion 43. The number of holes 31c is, for example, eight.

The internal gear 32 is annular and surrounds the radial outside of the external gear 31. More specifically, the internal gear 32 is annular and centered on the central axis J1. A gear portion having a plurality of teeth 32d is provided on the inner peripheral surface of the internal gear 32. The gear portion of the internal gear 32 meshes with the gear portion of the external gear 31. More specifically, the gear portion of the internal gear 32 meshes with the gear portion of the external gear 31 at a portion of the circumferential direction. As a result, the internal gear 32 meshes with the external gear 31.

As shown in FIG. 3, the internal gear 32 is located radially inside the peripheral wall portion 13k. The internal gear 32 is disposed on the upper surface of the bottom wall portion 13j. The upper surface 32e of the internal gear 32 is a flat surface perpendicular to the axial direction. The upper surface 32e of the internal gear 32 is located lower than the upper surface 13h of the peripheral wall portion 13k. The material constituting the internal gear 32 is metal. The metal constituting the internal gear 32 is, for example, iron. The internal gear 32 has an internal gear main body 32a and an annular protrusion 32b. The internal gear main body 32a is an annular portion with a gear portion provided on the inner peripheral surface. The lower surface of the radially outer portion of the internal gear main body 32a is in contact with the outer bottom surface portion 13m.

The annular protrusion 32b protrudes downward from the internal gear body 32a. More specifically, the annular protrusion 32b protrudes downward from the radially inner portion of the internal gear body 32a. The annular protrusion 32b is annular about the central axis J1. The annular protrusion 32b is fitted into the radially inner side of the step portion 13g. The lower surface of the annular protrusion 32b is a flat surface perpendicular to the axial direction. The lower surface of the annular protrusion 32b is in contact with the inner bottom surface portion 13i. The radial inner edge of the annular protrusion 32b is located at the same radial position as the radial inner edge of the internal gear body 32a.

As shown in FIG. 2, in this embodiment, the internal gear 32 has a second recess 32c on its outer circumferential surface. The second recess 32c is recessed radially inward. The second recess 32c, for example, penetrates the internal gear 32 in the axial direction. The interior of the second recess 32c is rectangular when viewed in the axial direction. In this embodiment, multiple second recesses 32c are provided at intervals in the circumferential direction. The multiple second recesses 32c are provided at equal intervals around the circumference. For example, four second recesses 32c are provided.

The internal gear 32 is fixed to the reduction mechanism case 13 by the fixing member 80. In other words, the fixing member 80 is a member that fixes the internal gear 32 to the case 11. The fixing member 80 is an annular member that surrounds the internal gear 32. More specifically, the fixing member 80 is annular about the central axis J1. The fixing member 80 is located radially between the internal gear 32 and the peripheral wall portion 13k. The fixing member 80 is in contact with the internal gear 32 and the peripheral wall portion 13k. The fixing member 80 is inserted between the internal gear 32 and the peripheral wall portion 13k and is crushed and deformed in the axial direction, thereby fixing the internal gear 32 to the peripheral wall portion 13k. The fixing member 80 has an annular portion 81, a pressing portion 82, a protruding portion 83, and an insertion portion 84.

The annular portion 81 is an annular portion that surrounds the internal gear 32 between the internal gear 32 and the peripheral wall portion 13k in the radial direction. As shown in FIG. 4, in this embodiment, the annular portion 81 is cylindrical, centered on the central axis J1 and open on both axial sides. In FIG. 4, the fixing member 180 before being deformed to fix the internal gear 32 is shown by a solid line, and the fixing member 80 after being deformed to fix the internal gear 32 is shown by a two-dot chain line. In reality, the fixing member 180 before being deformed and the fixing member 80 after being deformed have different dimensions, but in FIG. 4, the fixing member 180 before being deformed and the fixing member 80 after being deformed are shown in the same manner for the parts where only the dimensions have changed. The fixing member 180 before being deformed does not have an insertion portion 84.

As shown in FIG. 3, the annular portion 81 is in contact with the outer peripheral surface of the internal gear 32 and the inner peripheral surface of the peripheral wall portion 13k. The inner peripheral surface of the annular portion 81 is in contact with the outer peripheral surface of the internal gear main body 32a. The outer peripheral surface of the annular portion 81 is in contact with the inner peripheral surface of the peripheral wall portion 13k. The annular portion 81 applies a force F, for example, in a direction that pushes the outer peripheral surface of the internal gear 32 radially inward and in a direction that pushes the inner peripheral surface of the peripheral wall portion 13k radially outward.

The pressing portion 82 protrudes radially inward from the upper end of the annular portion 81. In this embodiment, the radially inner end of the pressing portion 82 is located radially inward from the step portion 13g. The pressing portion 82 contacts the upper surface 32e of the internal gear 32. More specifically, the lower surface of the pressing portion 82 contacts the upper surface 32e of the internal gear 32. As shown in FIG. 4, in this embodiment, the pressing portion 82 is annular about the central axis J1. The pressing portion 82 is plate-shaped with the plate surface facing the axial direction. As shown in FIG. 3, the upper surface 82a of the pressing portion 82 and the upper surface 13h of the peripheral wall portion 13k are arranged at the same position in the axial direction. In this embodiment, the upper surface 82a of the pressing portion 82 is continuously connected to the radially inner side of the upper surface 13h of the peripheral wall portion 13k without any step.

4, the protrusion 83 protrudes radially inward from the inner peripheral surface of the annular portion 81. In this embodiment, the protrusion 83 is a quadrangular prism extending in the axial direction. The protrusion 83 extends from the upper end to the lower end of the inner peripheral surface of the annular portion 81. The upper end of the protrusion 83 is connected to the pressing portion 82. The radially inner end of the protrusion 83 is located radially outward from the radial inner edge of the pressing portion 82. In this embodiment, the protrusions 83 are provided in a plurality of spaces in the circumferential direction. The plurality of protrusions 83 are provided at equal intervals around the circumference. For example, four protrusions 83 are provided. As shown in FIG. 2, each protrusion 83 is located inside each second recess 32c. Each protrusion 83 is in contact with the inner surface of each second recess 32c. Each protrusion 83 is filled in each second recess 32c, for example.

3 and 4, the insert portion 84 protrudes radially outward from the annular portion 81. More specifically, the insert portion 84 protrudes radially outward from the lower end of the outer circumferential surface of the annular portion 81. In this embodiment, the insert portion 84 is annular about the central axis J1. As shown in FIG. 3, the cross-sectional shape of the insert portion 84 perpendicular to the circumferential direction is triangular with an acute apex on the radially outer side. The upper surface of the insert portion 84 is a tapered surface that is located lower as it moves radially outward. The lower surface of the insert portion 84 is a flat annular surface perpendicular to the axial direction. The lower surface of the insert portion 84 is connected without any steps to the radially outer side of the lower surface of the annular portion 81.

The insert portion 84 is inserted inside the first recess 13f. The insert portion 84 is in contact with the inner surface of the first recess 13f. More specifically, the upper surface of the insert portion 84 is in contact with the upper surface of the inner surface of the first recess 13f. The lower surface of the insert portion 84 is in contact with the lower surface of the inner surface of the first recess 13f. In this embodiment, the insert portion 84 fills the inside of the first recess 13f.

In this embodiment, the material constituting the fixing member 80 is a metal. The metal constituting the fixing member 80 is, for example, aluminum. Here, as described above, the material constituting the reduction mechanism case 13 made by die casting is an alloy containing aluminum. Therefore, the material constituting the peripheral wall portion 13k is also an alloy containing aluminum. In other words, in this embodiment, the material constituting the fixing member 80 and the material constituting the peripheral wall portion 13k each contain aluminum as the same type of metal.

The hardness of the material constituting the fixing member 80 is less than the hardness of the material constituting the internal gear 32 and the hardness of the material constituting the peripheral wall portion 13k. In this specification, "hardness" refers to, for example, Vickers hardness, Brinell hardness, or Rockwell hardness. The hardness of the material constituting the internal gear 32 is greater than the hardness of the material constituting the peripheral wall portion 13k. The rigidity of the material constituting the fixing member 80 is less than the rigidity of the material constituting the internal gear 32 and the rigidity of the material constituting the peripheral wall portion 13k. The Young's modulus of the material constituting the fixing member 80 is less than the Young's modulus of the material constituting the internal gear 32 and the Young's modulus of the material constituting the peripheral wall portion 13k.

As shown in FIG. 1, the flange portion 42 is an annular plate that spreads radially around the central axis J1. The flange portion 42 is located below the external gear 31. The flange portion 42 spreads radially outward from the output shaft 41 described later. More specifically, the flange portion 42 spreads radially outward from the upper end of the output shaft 41. The lower surface of the contact protrusion 31b contacts the radially inner portion of the upper surface of the flange portion 42. A cylindrical second sensor magnet 74 centered on the central axis J1 is fixed to the lower surface of the flange portion 42. The rotation of the output shaft 41 can be detected by detecting the change in the magnetic field generated by the second sensor magnet 74 that rotates together with the output portion 40 using a second rotation sensor (not shown).

The multiple protrusions 43 protrude upward from the flange portion 42. That is, the multiple protrusions 43 protrude from the flange portion 42 toward the external gear 31. As shown in Figs. 1 and 2, the protrusions 43 are hollow and cylindrical. The inside of the protrusions 43 opens downward. As shown in Fig. 2, the multiple protrusions 43 are arranged along the circumferential direction. More specifically, the multiple protrusions 43 are arranged at equal intervals around one circumference along the circumferential direction centered on the central axis J1. The number of protrusions 43 is, for example, eight.

The multiple protrusions 43 are inserted into the multiple holes 31c, respectively. The outer peripheral surface of the protrusion 43 is inscribed in the inner peripheral surface of the hole 31c. As a result, the multiple protrusions 43 support the external gear 31 via the inner surface of the hole 31c so that it can swing around the central axis J1.

The output section 40 is a part that outputs the driving force of the electric actuator 10. As shown in FIG. 1, the output section 40 has an output shaft 41, a flange section 42, and a protrusion section 43. In other words, the flange section 42 and the protrusion section 43, which are part of the reduction mechanism 30 described above, are also part of the output section 40. In this embodiment, the output section 40 is a single member.

In this embodiment, the output shaft 41 extends in the axial direction of the motor shaft 21 below the motor shaft 21. The output shaft 41 is cylindrical and centered on the central axis J1. The output shaft 41 extends downward from the radial inner edge of the flange portion 42. The output shaft 41 is fitted into the radial inner side of the bush 54. The output shaft 41 is supported by the bush 54 so that it can rotate around the central axis J1. The output shaft 41 passes through the inside of the protruding tubular portion 13c. In this embodiment, the lower end of the output shaft 41 is located at the same axial position as the lower end of the protruding tubular portion 13c.

The output shaft 41 has a storage recess 41a and a connecting recess 41b. The storage recess 41a is recessed downward from the upper end of the output shaft 41. Although not shown, the storage recess 41a has a circular shape centered on the central axis J1 when viewed in the axial direction. The storage recess 41a stores the lower end of the motor shaft 21. In this embodiment, the seventh shaft portion 21g and the eighth shaft portion 21h are stored in the storage recess 41a. The lower end surface of the motor shaft 21 is located above the bottom surface of the storage recess 41a. The lower end surface of the motor shaft 21 faces the bottom surface of the storage recess 41a in the axial direction via a gap.

The connecting recess 41b is recessed upward from the lower end of the output shaft 41. Although not shown, the connecting recess 41b has a substantially circular shape centered on the central axis J1 when viewed in the axial direction. A plurality of spline grooves are provided along the circumferential direction on the inner peripheral surface of the connecting recess 41b. Another member to which the driving force of the electric actuator 10 is output is inserted and connected to the connecting recess 41b. The other member is, for example, a manual shaft in a vehicle. The electric actuator 10 drives the manual shaft based on the driver's shift operation to switch the gears of the vehicle.

When the motor shaft 21 rotates around the central axis J1, the sixth shaft portion 21f, which is an eccentric shaft portion, revolves in the circumferential direction around the central axis J1. The revolution of the sixth shaft portion 21f is transmitted to the external gear 31 via the second bearing 52, and the external gear 31 oscillates while changing the position where the inner circumferential surface of the hole portion 31c and the outer circumferential surface of the protrusion 43 are inscribed. As a result, the position where the gear portion of the external gear 31 and the gear portion of the internal gear 32 mesh with each other changes in the circumferential direction. Therefore, the rotational force of the motor shaft 21 is transmitted to the internal gear 32 via the external gear 31.

Here, in this embodiment, the internal gear 32 does not rotate because it is fixed to the reduction mechanism case 13. Therefore, the external gear 31 rotates around the eccentric axis J2 due to the reaction force of the rotational force transmitted to the internal gear 32. At this time, the direction of rotation of the external gear 31 is opposite to the direction of rotation of the motor shaft 21. The rotation of the external gear 31 around the eccentric axis J2 is transmitted to the flange portion 42 through the hole portion 31c and the protrusion portion 43. As a result, the output shaft 41 rotates around the central axis J1. In this way, the rotation of the motor shaft 21 is transmitted to the output shaft 41 through the reduction mechanism 30. The rotation of the output shaft 41 is reduced in speed by the reduction mechanism 30 with respect to the rotation of the motor shaft 21. According to the reduction mechanism 30 having the above-mentioned structure, the reduction ratio of the rotation of the output shaft 41 to the rotation of the motor shaft 21 can be made relatively large. Therefore, the rotation torque of the output shaft 41 can be made relatively large.

The preload member 60 is located axially between the outer ring of the third bearing 53 and the support wall portion 12f. The preload member 60 applies a downward elastic force to the outer ring of the third bearing 53. In this embodiment, the preload member 60 is, for example, a wave washer.

The circuit board 70 is a plate extending in a plane perpendicular to the axial direction. The circuit board 70 is accommodated in the motor case 12. More specifically, the circuit board 70 is accommodated in the circuit board accommodation portion 12g and is disposed above and away from the annular plate portion 12b. The circuit board 70 is a board that is electrically connected to the motor 20. The coil 23b is electrically connected to the circuit board 70. The circuit board 70 controls, for example, the current supplied to the motor 20. The circuit board 70 is equipped with, for example, an inverter circuit.

The mounting member 72 is annular about the central axis J1. The inner peripheral surface of the mounting member 72 is fixed to the upper end of the motor shaft 21, i.e., the outer peripheral surface of the first shaft portion 21a. The first sensor magnet 73 is annular about the central axis J1. The first sensor magnet 73 is fixed to the upper end surface of the radial outer edge of the mounting member 72. The first sensor magnet 73 has north and south poles arranged alternately along the circumferential direction. The first rotation sensor 71 is attached to the lower surface of the circuit board 70. The first rotation sensor 71 can be used to detect the change in the magnetic field generated by the first sensor magnet 73 rotating together with the motor shaft 21, thereby detecting the rotation of the motor shaft 21.

As shown in FIG. 5, the manufacturing method of the electric actuator 10 described above includes a fixing process FP in which the internal gear 32 is fixed to the case 11 using a fixing member 80. The fixing process FP includes an arrangement process S1 and a deformation process S2. The arrangement process S1 is a process in which the fixing member 180 before deformation and the internal gear 32 are arranged radially inside the peripheral wall portion 13k. In this embodiment, the arrangement process S1 includes an internal gear arrangement process S1a and a fixing member arrangement process S1b.

The internal gear arrangement process S1a is a process of arranging the internal gear 32 on the radial inside of the peripheral wall portion 13k. In the internal gear arrangement process S1a, the worker arranges the internal gear 32 on the upper side of the bottom wall portion 13j, as shown in FIG. 6. At this time, the annular protrusion 32b of the internal gear 32 is fitted into the radial inside of the stepped portion 13g.

In this specification, "workers, etc." includes workers who perform each task and assembly equipment, etc. Each task may be performed by a worker alone, by an assembly device alone, or by both a worker and an assembly device.

The fixing member arrangement process S1b is a process of arranging the fixing member 180 before deformation on the radial inside of the peripheral wall portion 13k. In this embodiment, the fixing member arrangement process S1b is performed after the internal gear arrangement process S1a. If the internal gear 32 can be arranged after the fixing member 180 is arranged, the fixing member arrangement process S1b may be performed before the internal gear arrangement process S1a. As shown in FIG. 6, in the fixing member arrangement process S1b, the worker or the like inserts the annular portion 181 of the fixing member 180 before deformation from above between the internal gear 32 and the peripheral wall portion 13k in the radial direction and arranges it. For example, a small gap is provided between at least one of the radial direction between the arranged annular portion 181 and the internal gear 32 and the radial direction between the annular portion 181 and the peripheral wall portion 13k. The axial dimension of the annular portion 181 is larger than the axial dimension of the annular portion 81 after deformation. The radial thickness between the inner and outer circumferential surfaces of the annular portion 181 is smaller than the radial thickness between the inner and outer circumferential surfaces of the annular portion 81 after deformation. The fixing member 180 placed in the fixing member placement process S1b is in a state where it protrudes above the upper surface 13h of the peripheral wall portion 13k.

The deformation process S2 is a process of deforming the fixed member 180, in which the annular portion 181 is disposed between the internal gear 32 and the peripheral wall portion 13k in the radial direction, by pressing it downward from above against the bottom wall portion 13j. As shown in FIG. 6, the worker applies a downward force to the fixed member 180 from above the pressing portion 82. As a result, the fixed member 180 is crushed in the axial direction and deformed, becoming the deformed fixed member 80 shown in FIG. 3. The worker, for example, uses a jig having a flat surface facing downward to apply a force from above to the pressing portion 82 through the flat surface. The worker, for example, crushes and deforms the fixed member 180 in the axial direction until the flat surface of the jig comes into contact with the upper surface 13h of the peripheral wall portion 13k.

In the deformation process S2, a part of the fixing member 180 is deformed and enters the first recess 13f. As a result, a part of the fixing member 180 is filled in the first recess 13f, and an insertion part 84 that conforms to the inner shape of the first recess 13f is created. The insertion part 84 is created, for example, by a part of the annular part 181 that is crushed in the axial direction entering the first recess 13f. As the annular part 181 is crushed in the axial direction by the deformation process S2, the lower surface of the pressing part 82 comes into contact with the upper surface 32e of the internal gear 32. Also, in the deformation process S2, the annular part 181 is deformed in a radially expanding direction and is pressed against the outer peripheral surface of the internal gear 32 and the inner peripheral surface of the peripheral wall part 13k. As a result, the internal gear 32 can be fixed to the peripheral wall part 13k by the deformed fixing member 80. In addition, in the deformation step S2, parts of the fixing member 180 other than the annular portion 181, such as the pressing portion 82, may also be deformed as appropriate.

According to this embodiment, a fixing member 80 having an annular portion 81 that contacts the outer peripheral surface of the internal gear 32 and the inner peripheral surface of the peripheral wall portion 13k is provided. The hardness of the material constituting the fixing member 80 is smaller than the hardness of the material constituting the internal gear 32 and the hardness of the material constituting the peripheral wall portion 13k. Therefore, as in the above-mentioned fixing process FP, the fixing member 180 before deformation can be easily deformed by being crushed in the axial direction between the radial direction of the internal gear 32 and the peripheral wall portion 13k. This allows the annular portion 81 after deformation to be strongly pressed against the outer peripheral surface of the internal gear 32 and the inner peripheral surface of the peripheral wall portion 13k. Therefore, the frictional force generated between the annular portion 81 and the outer peripheral surface of the internal gear 32 and between the annular portion 81 and the inner peripheral surface of the peripheral wall portion 13k can be relatively large, and the internal gear 32 can be firmly fixed to the peripheral wall portion 13k by the frictional force. Therefore, the fixing strength of the internal gear 32 to the case 11 can be improved. This prevents problems such as the internal gear 32 coming off the case 11 and the internal gear 32 shifting relative to the case 11.

For example, when the internal gear 32 is directly press-fitted into the peripheral wall portion 13k, it is necessary to deform at least one of the peripheral wall portion 13k and the internal gear 32, which have a relatively high hardness. Therefore, when fixing the internal gear 32, a relatively large force needs to be applied to the internal gear 32, which may make it difficult to fix the internal gear 32. In contrast, according to this embodiment, the internal gear 32 can be easily and suitably fixed by deforming the fixing member 180, which has a relatively low hardness. Therefore, the internal gear 32 can be easily fixed compared to when the internal gear 32 is fixed by press-fitting into the peripheral wall portion 13k. This improves the ease of assembly of the electric actuator 10.

In addition, according to this embodiment, the material constituting the fixed member 80 is metal. Therefore, as described above, the fixed member 180 is easily deformed before deformation. Also, the fixed member 180 can be suitably deformed to conform to the shape of the radial gap between the internal gear 32 and the peripheral wall portion 13k. Therefore, the deformed fixed member 80 is easily and suitably attached to the internal gear 32 and the peripheral wall portion 13k. This makes it possible to increase the frictional forces between the fixed member 80 and the internal gear 32 and between the fixed member 80 and the peripheral wall portion 13k. Therefore, the fixing strength of the internal gear 32 to the case 11 can be further improved.

In addition, according to this embodiment, the material constituting the fixing member 80 and the material constituting the peripheral wall portion 13k each contain the same type of metal. Here, when the materials constituting two certain members each contain the same type of metal, the coefficient of friction between the two certain members tends to be relatively large. Therefore, by making the material constituting the fixing member 80 and the material constituting the peripheral wall portion 13k contain the same type of metal, the coefficient of friction between the fixing member 80 and the peripheral wall portion 13k can be relatively large. This makes it possible to more suitably increase the frictional force generated between the fixing member 80 and the peripheral wall portion 13k. Therefore, the fixing member 80 can be more firmly fixed to the peripheral wall portion 13k. Therefore, the fixing member 80 can more firmly fix the internal gear 32 to the peripheral wall portion 13k. This can further improve the fixing strength of the internal gear 32 to the case 11.

In addition, according to this embodiment, the inner circumferential surface of the peripheral wall portion 13k is provided with a first recess 13f recessed radially outward. The fixing member 80 has an insertion portion 84 inserted into the first recess 13f. The insertion portion 84 is in contact with the inner surface of the first recess 13f. Therefore, the frictional force between the insertion portion 84 and the first recess 13f can more firmly fix the fixing member 80 to the peripheral wall portion 13k. This allows the fixing member 80 to more firmly fix the internal gear 32 to the peripheral wall portion 13k. Therefore, the fixing strength of the internal gear 32 to the case 11 can be further improved. In addition, since the insertion portion 84 is caught on the inner surface of the first recess 13f from below, it is possible to more effectively prevent the fixing member 80 from slipping out from the peripheral wall portion 13k to the upper side. In addition, as described above, in the deformation step S2, a portion of the fixing member 180 can be deformed and inserted into the first recess 13f, so that when the fixing member 180 deforms, a portion of the fixing member 180 can escape into the first recess 13f. This makes it easier to deform the fixing member 180 in the deformation step S2.

In addition, according to this embodiment, the first recess 13f is annular and surrounds the internal gear 32. Therefore, the contact area between the insertion portion 84 and the first recess 13f can be increased. This makes it possible to increase the frictional force between the insertion portion 84 and the first recess 13f, and to more firmly fix the fixing member 80 to the peripheral wall portion 13k. Therefore, the fixing strength of the internal gear 32 to the case 11 can be further improved. In addition, when the fixing member 80 receives a force from above, the insertion portion 84 contacts the inner surface of the first recess 13f from below, so that the force received can be dispersed in the circumferential direction. This makes it possible to prevent the force from being concentrated on the insertion portion 84, and to prevent the insertion portion 84 from being damaged. In addition, in the deformation process S2, the amount of deformation of the fixing member 180 is easily made uniform over the entire circumference in the circumferential direction, so that the fixing member 180 can be deformed favorably. In addition, the first recess 13f can be easily made by cutting out a part of the inner circumferential surface of the peripheral wall portion 13k over the entire circumference by cutting.

In addition, according to this embodiment, the insertion portion 84 is filled inside the first recess 13f. Therefore, the contact area between the insertion portion 84 and the first recess 13f can be increased. This increases the frictional force between the insertion portion 84 and the first recess 13f, and the fixing member 80 can be fixed more firmly to the peripheral wall portion 13k. Therefore, the fixing strength of the internal gear 32 to the case 11 can be further improved.

In addition, according to this embodiment, the fixing member 80 has a pressing portion 82 that protrudes radially inward from the upper end of the annular portion 81. The pressing portion 82 is in contact with the upper surface of the internal gear 32. Therefore, the pressing portion 82 can press the internal gear 32 from above. This allows the pressing portion 82 to prevent the internal gear 32 from shifting upward. In addition, the pressing portion 82 can increase the upper surface of the fixing member 80. Therefore, when applying force from above to the fixing member 180 before deformation to deform it, applying force to the pressing portion 82 makes it easier to apply force to the fixing member 180. This makes it easier to deform the fixing member 180.

Furthermore, according to this embodiment, the upper surface 82a of the pressing portion 82 and the upper surface 13h of the peripheral wall portion 13k are disposed at the same position in the axial direction. Therefore, as described above, in the deformation process S2, a method can be adopted in which the fixing member 180 is deformed until the flat surface of the jig that presses the pressing portion 82 from above to below contacts the upper surface 13h of the peripheral wall portion 13k. Therefore, it is easy to know the timing to end the deformation process S2. This improves the workability in the deformation process S2.

In addition, according to this embodiment, the internal gear 32 has a second recess 32c on the outer circumferential surface. The fixing member 80 has a protrusion 83 located inside the second recess 32c. Therefore, the protrusion 83 is caught in the circumferential direction on the inner surface of the second recess 32c. This makes it possible to more effectively prevent the fixing member 80 and the internal gear 32 from rotating relative to each other. Therefore, the fixing member 80 and the internal gear 32 can be more firmly fixed. Therefore, the fixing strength of the internal gear 32 to the case 11 can be further improved. The protrusion 83 may be deformed along the inner surface of the second recess 32c by the deformation process S2. In this case, the protrusion 83 is firmly fixed in the second recess 32c, and the internal gear 32 and the fixing member 80 are more firmly fixed.

In addition, according to this embodiment, the bottom wall portion 13j has an annular stepped portion 13g on its upper surface that surrounds the central axis J1. The internal gear 32 has an annular convex portion 32b that protrudes downward and is fitted into the radially inner side of the stepped portion 13g. Therefore, the internal gear 32 can be positioned in the radial direction by the stepped portion 13g. This makes it possible to prevent the internal gear 32 from shifting in the radial direction due to deformation of the fixing member 180 when the fixing member 180 before deformation is deformed to fix the internal gear 32 to the peripheral wall portion 13k. Therefore, the internal gear 32 can be fixed with good axial accuracy.

The present invention is not limited to the above-described embodiment, and other configurations may be adopted. The material constituting the fixing member may be any material as long as it is less hard than the material constituting the internal gear and the material constituting the peripheral wall portion. When the material constituting the fixing member is a metal, the metal constituting the fixing member may be copper or the like. The material constituting the fixing member may be other than a metal. The material constituting the fixing member and the material constituting the peripheral wall portion do not have to contain the same type of metal. The material constituting the internal gear and the material constituting the peripheral wall portion may contain the same type of metal.

The insertion portion of the fixing member may not be located in a part of the first recess, so long as it is located at least in a part of the first recess. The insertion portion of the fixing member may not be provided. In this case, the inner peripheral surface of the peripheral wall portion may not be provided with the first recess. The shape of the first recess is not particularly limited, and it may not be annular. A plurality of first recesses may be provided. In this case, the fixing member may have a plurality of insertion portions inserted into each of the first recesses. The pressing portion of the fixing member may protrude from the peripheral wall portion toward the other axial side (upper side), or may be recessed from the peripheral wall portion toward one axial side (lower side). The pressing portion may not be provided. The number of protruding portions of the fixing member and the number of second recesses of the internal gear are not particularly limited. The protruding portion and the second recess may not be provided. The bottom wall portion of the case may not be provided with a step portion.

The applications of the electric actuator of the above-mentioned embodiment are not particularly limited. The electric actuator of the above-mentioned embodiment may be mounted on equipment other than a vehicle. Furthermore, the configurations described in this specification may be combined as appropriate within the scope of not being mutually contradictory.

10...electric actuator, 11...case, 13f...first recess, 13g...step, 13j...bottom wall, 13k...peripheral wall, 20...motor, 21...motor shaft, 30...reduction mechanism, 31...external gear, 32...internal gear, 32b...annular protrusion, 32c...second recess, 80, 180...fixing member, 81, 181...annular portion, 82...pressing portion, 83...protruding portion, 84...insertion portion, FP...fixing process, J1...center axis, S2...deformation process

Claims (11)

a motor having a motor shaft rotatable about a central axis extending in an axial direction;
a reduction mechanism including an external gear connected to the motor shaft and an annular internal gear surrounding the radial outside of the external gear;
a case that accommodates the motor and the reduction mechanism therein;
A fixing member that fixes the internal gear to the case;
Equipped with
The case is
a bottom wall portion supporting the internal gear from one axial side;
A peripheral wall portion located radially outside the internal gear and surrounding the internal gear;
having
the fixing member has an annular portion that surrounds the internal gear between the internal gear and the peripheral wall portion in the radial direction,
the annular portion contacts an outer circumferential surface of the internal gear and an inner circumferential surface of the peripheral wall portion,
the hardness of a material constituting the fixing member is lower than the hardness of a material constituting the internal gear and the hardness of a material constituting the peripheral wall portion,
A first recess is provided on an inner circumferential surface of the peripheral wall portion and recessed radially outward,
the fixing member has an insertion portion inserted into the first recess,
The insertion portion is in contact with the inner surface of the first recess. a motor having a motor shaft rotatable about a central axis extending in an axial direction;
a reduction mechanism including an external gear connected to the motor shaft and an annular internal gear surrounding the radial outside of the external gear;
a case that accommodates the motor and the reduction mechanism therein;
A fixing member that fixes the internal gear to the case;
Equipped with
The case is
a bottom wall portion supporting the internal gear from one axial side;
A peripheral wall portion located radially outside the internal gear and surrounding the internal gear;
having
the fixing member has an annular portion that surrounds the internal gear between the internal gear and the peripheral wall portion in the radial direction,
the annular portion contacts an outer circumferential surface of the internal gear and an inner circumferential surface of the peripheral wall portion,
the hardness of a material constituting the fixing member is lower than the hardness of a material constituting the internal gear and the hardness of a material constituting the peripheral wall portion,
The internal gear has a second recess on an outer circumferential surface,
The fixing member is an electric actuator having a protrusion located inside the second recess. The electric actuator according to claim 1 or 2, wherein the material constituting the fixing member is metal. The electric actuator according to claim 3 , wherein a material constituting the fixing member and a material constituting the peripheral wall portion each contain the same type of metal. The electric actuator according to claim 1 , wherein the first recess is annular and surrounds the internal gear. The electric actuator according to claim 1 , wherein the insertion portion is filled inside the first recess. the fixing member has a pressing portion protruding radially inward from an end portion on the other axial side of the annular portion,
The electric actuator according to claim 1 , wherein the pressing portion is in contact with a surface of the internal gear on the other axial side. The electric actuator according to claim 6 , wherein the other axial side surface of the pressing portion and the other axial side surface of the peripheral wall portion are disposed at the same position in the axial direction. the bottom wall portion has an annular step portion surrounding the central axis on the other axial side surface,
The electric actuator according to claim 1 , wherein the internal gear has an annular protrusion protruding to one axial side and fitted into a radially inner side of the stepped portion. A method for manufacturing an electric actuator including: a motor having a motor shaft rotatable about a central axis extending in an axial direction; a reduction mechanism having an external gear connected to the motor shaft and an annular internal gear surrounding a radial outside of the external gear; and a case that accommodates the motor and the reduction mechanism therein,
a fixing step of fixing the internal gear to the case using a fixing member having an annular portion,
The case is
a bottom wall portion supporting the internal gear from one axial side;
A peripheral wall portion located radially outside the internal gear and surrounding the internal gear;
having
the hardness of the fixing member is lower than the hardness of the internal gear and the hardness of the peripheral wall portion,
the fixing step includes a deformation step of deforming the fixing member, with the annular portion disposed radially between the internal gear and the peripheral wall portion, by pressing the fixing member from the other axial side toward the one axial side to the bottom wall portion,
In the deformation process, the annular portion is deformed and pressed against an outer circumferential surface of the internal gear and an inner circumferential surface of the peripheral wall portion,
A first recess is provided on an inner circumferential surface of the peripheral wall portion and recessed radially outward,
In the deformation process, a portion of the fixing member is deformed and enters into the first recess.
A manufacturing method for an electric actuator. a motor having a motor shaft rotatable about a central axis extending in an axial direction;
a reduction mechanism including an external gear connected to the motor shaft and an annular internal gear surrounding the radial outside of the external gear;
a case that accommodates the motor and the reduction mechanism therein;
A fixing member that fixes the internal gear to the case;
Equipped with
The case is
a bottom wall portion supporting the internal gear from one axial side;
A peripheral wall portion located radially outside the internal gear and surrounding the internal gear;
having
the fixing member has an annular portion that surrounds the internal gear between the internal gear and the peripheral wall portion in the radial direction,
the annular portion contacts an outer circumferential surface of the internal gear and an inner circumferential surface of the peripheral wall portion,
the hardness of a material constituting the fixing member is lower than the hardness of a material constituting the internal gear and the hardness of a material constituting the peripheral wall portion,
A first recess is provided on an inner circumferential surface of the peripheral wall portion and recessed radially outward,
a portion of the fixing member contacts an inner surface of the first recess;
The internal gear has a second recess on an outer circumferential surface,
A portion of the fixing member is located inside the second recess.
Electric actuator.

Images