JP6358054B2 - Rotary actuator - Google Patents

Description

  The present invention relates to a rotary actuator.

  Conventionally, for example, a rotary actuator used in a drive unit of a shift-by-wire system of a vehicle is known. The rotary actuator disclosed in Patent Document 1 includes a motor, a speed reduction mechanism that decelerates the rotation of the motor, an output member that outputs the decelerated rotation to the outside, and a case that houses the motor and the speed reduction mechanism. I have.

  The case is composed of a bottomed cylindrical first case and a second case. The first case and the second case are fixed such that the opening ends are abutted with each other. The motor shaft has one end supported by the first case and the other end supported by the second case via the output member. One end of the stator of the motor is press-fitted into the first case, and the other end is inserted into the second case.

JP 2009-177982 A

  By the way, in the rotary actuator configured as described above, the mutual position and inclination accuracy (axial accuracy) between the support shaft center of the first case and the support shaft center of the second case are different from those of the other end portion of the stator. It is almost determined by the size of the clearance between the second case. That is, the smaller the clearance, the higher the axial accuracy.

However, the clearance is absolutely necessary when assembling the first case to which the motor, a part of the speed reduction mechanism and the output member are attached, and the second case to which a part of the speed reduction mechanism is attached. Therefore, there has been a limit to improving the performance such as reducing the variation in output torque among individuals by reducing the clearance and increasing the shaft accuracy.
The present invention has been made in view of the above points, and an object of the present invention is to provide a rotary actuator having improved axial accuracy without deteriorating the assembling property between the first case and the second case. is there.

In the present invention, the other end portion of the stator has a cylindrical outer wall portion that is formed along a first virtual cylindrical surface that is a virtual cylindrical surface centered on the axis of the stator, and a first virtual cylindrical surface. And a protruding portion protruding radially outward. The second case is concentric with the first virtual cylindrical surface and has a cylindrical inner wall portion formed along the second virtual cylindrical surface having a diameter larger than that of the first virtual cylindrical surface, and the protruding portion. And an interval decreasing portion that is formed so as to protrude radially inward with respect to the second virtual cylindrical surface at a position overlapping in the circumferential direction. The stator core of the stator forms a cylindrical yoke and a plurality of teeth protruding radially inward from the yoke. The circumferential position of the central portion of the protruding portion coincides with the center of the tooth.

  Therefore, when assembling the first case to which the motor, a part of the speed reduction mechanism and the output member are attached, and the second case to which a part of the speed reduction mechanism is attached, for example, the interval between the protrusion of the stator and the second case After the second case is placed on the outside of the stator with the circumferential position of the decreasing portion shifted, the second case is moved relative to the first case so that the circumferential positions of the projecting portion and the interval decreasing portion coincide with each other. What is necessary is just to move to the circumferential direction.

  In this way, in the first stage in which the second case is placed on the outside of the stator, there is a clearance between the stator and the second case, and the second stage in which the circumferential positions of the protruding portion and the interval reducing portion are made to coincide. Then, the clearance between the stator and the second case is reduced. Depending on the dimensional design of the projecting portion and the interval decreasing portion, the clearance between the stator and the second case can be eliminated in the second stage. Therefore, the shaft accuracy can be improved without deteriorating the assembling property between the first case and the second case.

It is sectional drawing of the rotary actuator by 1st Embodiment of this invention. It is the II-II sectional view taken on the line of the rotary actuator of FIG. It is an enlarged view of the III part of FIG. FIG. 4 is an enlarged view of a portion IV in FIG. 3. FIG. 2 is a diagram showing a state before assembling the first case and the second case in the middle of assembling the constituent members of the rotary actuator of FIG. 1. FIG. 2 is a diagram illustrating a state in which the output member attached to the first case and the bearing attached to the second case are fitted to each other during the assembly of the constituent members of the rotary actuator of FIG. 1. FIG. 2 is a diagram illustrating a state in which a second case is placed on the outside of a stator while the ring gear and the planetary gear are engaged with each other while the constituent members of the rotary actuator of FIG. 1 are being assembled. FIG. 2 is a diagram illustrating a state in which the circumferential positions of the protruding portion of the stator and the interval reduction portion of the second case are shifted while assembling the constituent members of the rotary actuator of FIG. 1. It is sectional drawing of the rotary actuator by 2nd Embodiment of this invention, Comprising: It is a figure equivalent to FIG. 4 in 1st Embodiment. FIG. 10 is a diagram illustrating a state in which the circumferential positions of the protruding portion of the stator and the interval reduction portion of the second case are shifted during the assembly of the constituent members of the rotary actuator of FIG. 9. It is sectional drawing of the rotary actuator by 3rd Embodiment of this invention, Comprising: It is a figure equivalent to FIG. 4 in 1st Embodiment. FIG. 12 is a diagram illustrating a state in which the circumferential positions of the projecting portion of the stator and the interval reduction portion of the second case are shifted while assembling the constituent members of the rotary actuator of FIG. 11. It is sectional drawing of the rotary actuator by 4th Embodiment of this invention, Comprising: It is a figure which expands and shows the other end part of the yoke of a stator core, and the fitting part of the 2nd case covered on it. FIG. 14 is a diagram illustrating a state in which the constituent members of the rotary actuator of FIG. 13 are being assembled and before the fitting portion of the second case is put on the outside of the stator.

Hereinafter, a plurality of embodiments of the present invention will be described with reference to the drawings. In the embodiments, substantially the same components are denoted by the same reference numerals and description thereof is omitted.
[First Embodiment]
A rotary actuator according to a first embodiment of the present invention is shown in FIG. The rotary actuator 10 is used, for example, as a drive unit of a vehicle shift-by-wire system.

(overall structure)
First, the overall configuration of the rotary actuator 10 will be described with reference to FIGS. 1 and 2.
The rotary actuator 10 includes a case 20, a motor 30, a speed reduction mechanism 50, and an output member 60.

  The case 20 includes a cup-shaped first case 21 and a second case 22. The first case 21 and the second case 22 are fixed by bolts 24 with their open end portions butting each other. A cup-shaped metal plate 23 is embedded in the first case 21.

The motor 30 is a switched reluctance motor and includes a stator 31, a rotor 41, and a motor shaft 44.
The stator 31 has a stator core 32 and a plurality of coils 37. The stator core 32 forms a cylindrical yoke 33 and a plurality of teeth 34 projecting radially inward from the yoke 33 and around which a coil 37 is wound. One end portion 35 of the yoke 33 is press-fitted inside the metal plate 23, and the other end portion 36 is fitted to the second case 22. For example, twelve teeth 34 are provided at equal intervals in the circumferential direction. In the present embodiment, the stator core 32 is made by laminating a plurality of metal plates in the axial direction.

  The rotor 41 is rotatably provided inside the stator 31, and includes a cylindrical boss 42 and a plurality of salient poles 43 protruding radially from the boss 42. For example, eight salient poles 43 are provided at equal intervals in the circumferential direction. In the present embodiment, the rotor 41 is made by laminating a plurality of metal plates in the axial direction.

  The motor shaft 44 is press-fitted inside the rotor 41 and can rotate integrally with the rotor 41. One end portion 45 of the motor shaft 44 is rotatably supported by the first case 21 via a bearing 48, and the other end portion 46 of the motor shaft 44 is rotatable by an output member 60 via a bearing 49. It is supported by. The motor shaft 44 forms an eccentric portion 47 that is eccentric with respect to the one end portion 45 and the other end portion 46 between the one end portion 45 and the other end portion 46.

  The reduction mechanism 50 is a kind of planetary gear device, and includes a ring gear 51 and a planetary gear 52. The ring gear 51 is provided coaxially with the axial center AX1 of the one end 45 and the other end 46 and is fixed to the second case 22. The planetary gear 52 is provided coaxially with the eccentric shaft center AX2 that is the shaft center of the eccentric portion 47, meshes with the ring gear 51 so as to be inscribed therein, and is supported by the eccentric portion 47 via the bearing 54 so as to be capable of planetary movement. Yes. The planetary motion is a motion that revolves around the axis AX1 while rotating around the eccentric axis AX2. The rotation speed of the planetary gear 52 during planetary movement is changed with respect to the rotation speed of the motor shaft 44. The planetary gear 52 forms a rotation transmission protrusion 53 protruding in the axial direction.

  The output member 60 is provided coaxially with the shaft center AX1, is rotatably supported by the second case 22 via a bearing 61, and has a through hole 62 into which the protrusion 53 is inserted. The rotation of the planetary gear 52 is transmitted to the output member 60 through an engaging portion between the projection 53 and the inner wall of the through hole 62.

  In the rotary actuator 10 configured as described above, when the coil 37 is energized sequentially for each phase, a rotating magnetic field is generated, and the rotor 41 receives the magnetic attractive force or repulsive force generated by the rotating magnetic field. Rotate. When the motor shaft 44 rotates about the axis AX1 together with the rotor 41, the planetary gear 52 performs planetary motion, and the rotation of the planetary gear 52 decelerated with respect to the rotation of the motor shaft 44 is output from the output member 60 to the outside.

(Feature configuration)
Next, a characteristic configuration of the rotary actuator 10 will be described with reference to FIGS. 3 and 4 are straight lines extending radially from an unillustrated axis AX1, and each straight line is described around the axis AX1 at intervals of 15 °.
As shown in FIGS. 2 to 4, the outer wall of the yoke 33 has a cylindrical outer wall portion 71 and a protruding portion 72. The cylindrical outer wall portion 71 is formed along the first virtual cylindrical surface S1, which is a virtual cylindrical surface centered on the axial center of the stator 31, that is, the axial center AX1. The protrusion 72 is formed to protrude radially outward with respect to the first virtual cylindrical surface S1.

In the present embodiment, the same number of protrusions 72 as the teeth 34 are provided. The protrusions 72 are provided around the axis AX1 at 30 ° intervals.
The protrusion 72 is provided at a location where the circumferential position coincides with the center of the tooth 34. A portion where the circumferential position coincides with the center of the tooth 34 is a portion of the yoke 33 having the highest rigidity in the circumferential direction.
Moreover, the opposing surface 73 facing the second case 22 in the radial direction in the protruding portion 72 is a convex curved surface. That is, the facing surface 73 is formed so as to be separated from the second case 22 as it goes from the central portion (top portion) in the circumferential direction to the end portion (hem portion).

  The fitting portion 74 that is fitted to the other end portion 36 of the yoke 33 in the second case 22 has a cylindrical inner wall portion 75 and an interval reducing portion 76. The cylindrical inner wall portion 75 is formed along the second virtual cylindrical surface S2 that is concentric with the first virtual cylindrical surface S1 and has a larger diameter than the first virtual cylindrical surface S1. The interval decreasing portion 76 is formed so as to protrude radially inward with respect to the second virtual cylindrical surface S2 at a circumferential position that coincides with the protruding portion 72, and decreases the interval with the stator 31. The cylindrical inner wall portion 75 faces the cylindrical outer wall portion 71 with a gap 77 therebetween.

In this embodiment, the interval decreasing part 76 is a protrusion, and 12 pieces are provided. The interval decreasing portions 76 are provided at intervals of 30 ° around the axis AX1.
Moreover, the opposing surface 78 which faces the yoke 33 in the radial direction in the interval decreasing portion 76 is a convex curved surface. That is, the facing surface 78 is formed so as to move away from the yoke 33 as it goes from the center (top) in the circumferential direction to the end (bottom). The opposing surface 73 and the opposing surface 78 are in contact with each other at the center.

  When assembling the components of the rotary actuator 10 configured in this way, first, as shown in FIG. 5, the motor 30, the planetary gear 52, and the output member 60 are attached to the first case 21, and the ring gear 51 is 2 The case 22 is attached.

  Subsequently, as shown in order in FIGS. 6 to 8, the first case 21 and the second case 22 are assembled so that the opening ends are brought into contact with each other. Specifically, the output member 60 and the bearing 61 are first fitted as shown in FIG. Next, as shown in FIG. 7, the ring gear 51 and the planetary gear 52 are engaged with each other, and the circumferential position of the projecting portion 72 of the stator 31 and the interval reducing portion 76 of the second case 22 is shifted as shown in FIG. Thus, as shown in FIG. 7, the second case 22 is placed on the outside of the stator 31. Next, as shown in FIGS. 3 and 4, the second case 22 is moved in the circumferential direction with respect to the first case 21 so that the circumferential positions of the protrusions 72 and the interval reduction portions 76 coincide. Finally, the first case 21 and the second case 22 are fixed with bolts 24.

(effect)
As described above, in the first embodiment, the other end portion 36 of the yoke 33 is opposed to the cylindrical outer wall portion 71 formed along the first virtual cylindrical surface S1 and the first virtual cylindrical surface S1. And a projecting portion 72 projecting radially outward. The fitting portion 74 of the second case 22 is formed along the second virtual cylindrical surface S2, and has a cylindrical inner wall portion 75 facing the cylindrical outer wall portion 71 with a gap 77 therebetween, and a protruding portion. 72 is formed so as to protrude radially inward with respect to the second virtual cylindrical surface S <b> 2 at a circumferential position that coincides with 72, and has an interval reduction portion 76 that reduces the interval with the stator 31.

  With this configuration, as shown in FIG. 8, there is a clearance between the stator 31 and the second case 22 at the stage where the second case 22 is placed outside the stator 31, as shown in FIGS. As described above, the clearance between the stator 31 and the second case 22 is reduced at the stage in which the circumferential positions of the projecting portion 72 and the interval reducing portion 76 are matched. Therefore, the shaft accuracy can be improved without deteriorating the assembling property between the first case 21 and the second case 22.

Moreover, in 1st Embodiment, the center part has contacted the opposing surface 73 of the protrusion part 72, and the opposing surface 78 of the space | interval reduction | decrease part 76 without gap.
Therefore, the clearance between the stator 31 and the second case 22 can be eliminated, and the shaft accuracy can be further improved.

In the first embodiment, three or more projecting portions 72 and interval reducing portions 76 are provided.
For this reason, the first case 21 and the second case 22 can be centered by matching the circumferential positions of the protruding portion 72 and the interval reducing portion 76.

Moreover, in 1st Embodiment, the opposing surface 78 of the space | interval reduction | decrease part 76 is a convex surface.
Thereby, the opposing surface 78 is formed so that it may leave | separate from the stator 31 as it goes to the edge part from the center part of the circumferential direction. Therefore, when the circumferential positions of the projecting portion 72 and the interval reducing portion 76 are matched during assembly, the catching between the interval reducing portion 76 and the projecting portion 72 is suppressed, and the second case 22 is surrounded by the first case 21. It can be moved smoothly in the direction.

[Second Embodiment]
In 2nd Embodiment of this invention, as shown in FIG. 9, the opposing surface 82 which opposes the protrusion part 72 among the space | interval reduction parts 81 is a plane. Thus, even if the opposing surface 82 is a flat surface, it is formed so as to be separated from the yoke 33 as it goes from the central portion to the end portion in the circumferential direction. Therefore, as in the first embodiment, when matching the circumferential position of the protruding portion 72 and the interval reducing portion 81 from the state of FIG. 10 during assembly, the catch between the interval reducing portion 81 and the protruding portion 72 is suppressed, The second case 22 can be smoothly moved in the circumferential direction with respect to the first case 21.
Moreover, in 3rd Embodiment, the location corresponding to the opposing surface 82 is a plane among the metal mold | die which shape | molds the 2nd case 22. FIG. Therefore, it becomes easy to make a mold.

[Third Embodiment]
In the third embodiment of the present invention, as shown in FIG. 11, the interval reducing portion 85 is a protrusion that protrudes radially inward with respect to the second virtual cylindrical surface S <b> 2 and faces the protrusion 72. The facing surface 86 is a concave curved surface. Thus, even if the facing surface 86 is a concave curved surface, if the protruding portion 72 is a convex curved surface, it is formed so as to be separated from the yoke 33 as it goes from the central portion to the end portion in the circumferential direction. Therefore, as in the first embodiment, when matching the circumferential position of the protruding portion 72 and the interval reducing portion 85 from the state of FIG. 12 during assembly, the catch between the interval reducing portion 85 and the protruding portion 72 is suppressed, The second case 22 can be smoothly moved in the circumferential direction with respect to the first case 21.

  In the third embodiment, the facing surface 86 is an arcuate concave curved surface whose curvature center line coincides with the axis AX1. For this reason, the facing surface 86 is not limited to the central portion, and can be in contact with the protruding portion 72 without any gap even at the end portion. Therefore, it is possible to allow variation in the angle at which the second case 22 is rotated with respect to the first case 21 when the circumferential positions of the projecting portion 72 and the interval reducing portion 85 are matched during assembly.

[Fourth Embodiment]
In 4th Embodiment of this invention, as shown in FIG. 13, the opposing surface 92 facing the protrusion part 72 among the space | interval reduction | decrease parts 91 is the 2nd case 22 side from the 1st case 21 side in an axial direction. It includes an inclined surface 93 that is inclined so as to approach the protrusion 72 as it goes. Therefore, when the second case 22 is put on the outside of the stator 31 from the state of FIG. 14 when assembled, the protrusion 72 is inclined even if the circumferential positions of the protrusion 72 and the interval reduction portion 91 coincide. The second case 22 is centered with respect to the stator 31 by being guided by 93. Therefore, the catch between the interval reducing portion 91 and the protruding portion 72 is suppressed, and the second case 22 can be smoothly moved in the axial direction with respect to the first case 21.

[Other Embodiments]
In 1st-4th embodiment, the space | interval reduction | decrease part was formed so that a protrusion part may contact just without a clearance gap. On the other hand, in other embodiments of the present invention, the interval decreasing portion may be formed so as not to contact the protruding portion. In short, the interval decreasing portion may be formed so as to protrude radially inward with respect to the second virtual cylindrical surface. In another embodiment of the present invention, the interval reducing portion is formed to have a diameter larger than that of the protruding portion before assembly, and is crushed by the engagement with the protruding portion at the time of assembly so as to be in close contact with the protruding portion. It may be configured.

In other embodiments of the present invention, there may be fewer than twelve protrusions and spacing reductions, or more than twelve. By providing three or more projecting portions and interval decreasing portions, the second case can be centered with respect to the first case.
In another embodiment of the present invention, the protrusions and the interval reduction portions may not be provided at equal intervals in the circumferential direction.

In another embodiment of the present invention, the protrusion may not have a circumferential position that coincides with the center of the tooth. For example, the protrusion may be provided at a location where the circumferential position overlaps with the teeth, or may be provided at a location where the circumferential position overlaps with a slot between the teeth.
In another embodiment of the present invention, when an inclined surface is included in the opposing surface of the interval reducing portion, the opposing surface of the protruding portion and the opposing surface of the interval reducing portion may not be convex curved surfaces.

In another embodiment of the present invention, the motor is not limited to a switched reluctance motor, and may be another type of synchronous motor or the like.
In other embodiments of the present invention, the speed reduction mechanism may be another type of planetary gear unit, or may be of another type, such as a spur gear speed reduction mechanism.
In other embodiments of the present invention, the rotary actuator may be used in devices other than a vehicle shift-by-wire system.
The present invention is not limited to the embodiments described above, and can be implemented in various forms without departing from the spirit of the invention.

21 ... 1st case 22 ... 2nd case 31 ... Stator 35 ... One end part of a stator 36 ... Other end part of a stator 41 ... Rotor 44 ... Motor shaft 45 ...・ One end portion of motor shaft 46... Other end portion of motor shaft 50... Reduction mechanism 60... Output member 71 .. cylindrical outer wall portion 72. 76, 81, 85, 91... Interval reduction portion AX1 .. axis S1... First virtual cylindrical surface S2.

Claims (5)

A stator (31);
A rotor (41) rotatable inside the stator;
A motor shaft (44) rotatable integrally with the rotor;
A speed reduction mechanism (50) for reducing the rotation of the motor shaft;
A first case (21) that rotatably supports one end (45) of the motor shaft and is fitted to one end (35) of the stator;
An output member (60) capable of rotatably supporting the other end (46) of the motor shaft and outputting the rotation decelerated by the deceleration mechanism to the outside;
A second case (22) that rotatably supports the output member and is fitted to the other end (36) of the stator;
With
The other end portion of the stator has a cylindrical outer wall portion (71) formed along a first virtual cylindrical surface (S1) that is a virtual cylindrical surface centered on the axis (AX1) of the stator. And a projecting portion (72) projecting radially outward with respect to the first virtual cylindrical surface,
The second case has a cylindrical inner wall (75) that is concentric with the first virtual cylindrical surface and is formed along the second virtual cylindrical surface (S2) having a diameter larger than that of the first virtual cylindrical surface. ), And a distance reduction portion (76, 76) that is formed so as to protrude radially inward with respect to the second virtual cylindrical surface at a position overlapping in a circumferential direction with respect to the protrusion. and 81,85,91), I have a,
The stator core (32) of the stator forms a cylindrical yoke (33) and a plurality of teeth (34) protruding radially inward from the yoke,
The rotary actuator characterized in that a circumferential position of a central portion of the projecting portion coincides with a center of the tooth .   2. The rotary actuator according to claim 1, wherein three or more of the protruding portions and the interval reduction portions are provided.   3. The rotary actuator according to claim 1, wherein a facing surface (82) of the space decreasing portion (81) facing the protruding portion is a flat surface.   3. The rotary actuator according to claim 1, wherein a facing surface (73) of the space decreasing portion (76) facing the protruding portion is a convex surface. 4.   The opposed surface (92) of the space decreasing portion (91) facing the protruding portion is inclined so as to approach the protruding portion in the axial direction from the first case side to the second case side. The rotary actuator according to claim 1, further comprising an inclined surface (93).

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