JP2017169331A - Flat actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flat actuator of short axial length in which a motor and a gear speed reduction are coupled in the axial direction.SOLUTION: A flat actuator 1 has a main bearing 13, e.g., a double row angular ball bearing supporting a motor 2, an encoder 3, and the rotor shaft 10 of the motor 2 in a cantilevered state, and a wave gear speed reducer 4 for decelerating motor rotation taken out from the rotor shaft 10. The wave gear speed reducer 4 includes a cup-shaped flexible outer tooth gear 22 arranged coaxially with the rotor shaft 10, and the main bearing 13 is placed in the outer tooth gear. A portion of the rotor shaft 10 on the one first shaft end 10a side is supported by the main bearing 13 in the outer tooth gear 22, and a portion on the other second shaft end 10b side is projecting to the outside from the opening end of the outer tooth gear 22. The encoder 3 is attached to the second shaft end 10b.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a flat actuator provided with a motor and a wave gear reducer.

  Patent Document 1 proposes a rotary actuator including a motor and a wave gear reducer. The rotary actuator disclosed in Patent Document 1 has a configuration in which a hollow AC servomotor and a cup-shaped hollow wave gear device are arranged in the direction of the central axis.

  The output side portion of the hollow motor shaft of the AC servo motor extends through the front end plate of the motor housing into a flexible external gear having a cup shape of the hollow wave gear device. A wave generator is fixed to a portion of the hollow motor shaft extending inside the external gear. An encoder is attached to the opposite side of the hollow motor shaft. Further, the hollow motor shaft is supported in a both-end supported state at a constant interval in the axial direction by a front main bearing attached to the front end plate of the motor housing and a rear main bearing on the encoder side.

JP 2014-206265 A

  In such an actuator, the motor and the wave gear reducer are connected in the axial direction, and an encoder is attached to the rear end side of the motor.

  Further, the motor shaft needs to have a front end portion on the output side extending to the wave gear reducer side to provide a wave generator mounting portion, and a rear end portion to the rear side to provide an encoder mounting portion. . Therefore, the shaft length of the motor shaft tends to be long.

  In order to secure the supporting rigidity of the long motor shaft, it is necessary to support the motor shaft in a both-side supported state by the front main bearing and the rear main bearing which are arranged with an interval in the axial direction. For this reason, the space for arrange | positioning a bearing before and behind an axial direction is needed. Also from this point, the axial length of the actuator tends to be long.

  An actuator with a long shaft length may be difficult to incorporate unless a sufficient installation space is secured in the axial direction.

  In view of these points, an object of the present invention is to provide a flat actuator having a short axial length in which a motor and a wave gear reducer are coupled in the axial direction.

In order to solve the above problems, the flat actuator of the present invention is
A motor,
An encoder for detecting the rotational state of the motor;
A main bearing such as a combined angular ball bearing that supports the rotor shaft of the motor in a cantilever state;
A wave gear reducer that decelerates the motor rotation taken from the rotor shaft;
Have
The wave gear reducer includes a cup-shaped flexible external gear disposed coaxially with the rotor shaft,
The main bearing is disposed inside the external gear,
The rotor shaft has a portion on the side of one first shaft end located inside the external gear and is supported by the main bearing, and a portion on the side of the other second shaft end of the external gear. Protrudes from the open end to the outside,
The encoder is attached to the end of the second shaft of the rotor shaft.

  In the flat actuator of the present invention, the main bearing is arranged using the internal space of the cup-shaped external gear, and the rotor shaft is supported in a cantilever state by the main bearing. The second shaft end portion side) can be free.

  2. Description of the Related Art Conventionally, a portion of a rotor shaft that protrudes outside from an external gear of a wave gear reducer is supported in a doubly supported state by a pair of main bearings arranged at predetermined intervals along the axial direction. The second shaft end portion on the encoder side of the rotor shaft cannot be free.

  In the present invention, since the rear end side of the rotor shaft can be set in a free state, the installation space for the pair of main bearings on the motor (encoder) side can be omitted. it can. Further, since the rotor shaft can be shortened, if a bearing having a high load capacity such as a combined angular ball bearing is used, the rotor shaft can be supported in a cantilever state with sufficient support rigidity. Furthermore, since the main bearing of the rotor shaft does not exist on the encoder side, it is not necessary to arrange a part for preventing scattering of the bearing lubricating oil for lubricating the main bearing. That is, it is not necessary to arrange a dedicated member for preventing the grease or lubricating oil from scattering to the encoder. Therefore, according to the present invention, it is possible to realize a flat actuator having a shorter axial length than the conventional one.

  Further, in the present invention, the rear end side of the rotor shaft can be made free, and the main bearing and the holding mechanism for the main bearing are not necessary on the encoder side, so that the processing accuracy of the members on the encoder side is relaxed. And the assemblability can be improved. Therefore, according to the present invention, a flat actuator can be realized, and processing costs and assembly costs of the flat actuator can be suppressed.

  Next, in the flat actuator of the present invention, a wave generator of the wave gear reducer is attached to the shaft portion between the main bearing and the encoder in the rotor shaft on the first shaft end side, A rotor disk having a rotor magnet fixed to the outer peripheral part is attached to the second shaft end, and the wave generator and the rotor disk are partitioned by a speed reducer case, and the speed reducer case and the speed reducer A gap between the rotor shaft extending through the case can be sealed with an oil seal.

  According to this configuration, the motor and the wave gear reducer are partitioned by the reducer case and the oil seal. Grease can be prevented from leaking from the wave gear reducer side to the motor side. It is possible to prevent the adverse effect that the grease leaked to the motor side is scattered by the rotation of the rotor to the adjacent encoder side and adheres to the encoder.

It is a schematic longitudinal cross-sectional view which shows the flat actuator to which this invention is applied. It is a partial expanded sectional view of the flat actuator of FIG.

  Embodiments of a flat actuator to which the present invention is applied will be described below with reference to the drawings.

  FIG. 1 is a schematic longitudinal sectional view showing a flat actuator according to the present embodiment. The flat actuator 1 includes a motor 2, an encoder 3 that detects the rotation state of the motor 2, and a wave gear reducer 4 that decelerates the motor rotation.

  The motor 2 includes a stator assembly 6 and a rotor assembly 7 which are coaxially incorporated inside a motor case 5 having an end plate portion 5a and a cylindrical body portion 5b. The stator assembly 6 includes a stator coil 9 wound around each salient pole of a stator core 8 attached to the inner peripheral surface of the motor case 5. The rotor assembly 7 includes a rotor shaft 10, a rotor disk 11 that rotates integrally with the rotor shaft 10, and a rotor magnet 12 that is attached to the outer periphery of the rotor disk 11.

  The wave gear reducer 4 includes a reducer case 20 fixed to the motor case 5. A rigid internal gear 21 is integrally formed at a portion on the inner peripheral side of the speed reducer case 20. A cup-shaped flexible external gear 22 is coaxially arranged on the inner side, and a wave generator 23 having an elliptical contour is fitted on the inner side. The wave generator 23 is fixed to the rotor shaft 10 of the motor 2, and the output shaft 24 is fixed to the external gear 22. A main bearing 13 of the motor 2 is disposed inside the external gear 22, and the rotor shaft 10 is supported in a cantilevered state by the main bearing 13. That is, the end of the rotor shaft 10 on the encoder 3 side is in a free state.

  In this example, a combination angular contact ball bearing is used as the main bearing 13. Of course, other types of rolling bearings may be used as the main bearing 13. For example, a double row deep groove ball bearing or the like can be used, and the main bearing 13 is not limited to a combination angular ball bearing.

  The structure of each part will be specifically described. First, the rotor shaft 10 of the motor 2 is disposed along the central axis 1 a of the flat actuator 1. The portion of the rotor shaft 10 on the output-side first shaft end portion 10 a side is located inside the external gear 22 and is supported by the main bearing 13 in a rotatable state. A portion on the second shaft end portion 10 b side that is the other counter-output end (rear end) of the rotor shaft 10 protrudes from the opening end of the external gear 22. The second shaft end portion 10b protrudes outward from the end plate portion 5a on the rear end side of the motor case 5, and the rotation side portion of the encoder 3 is fixed to the protruding portion in a coaxial state.

  The rotor disk 11 is coaxially fixed to the shaft portion of the rotor shaft 10 on the side of the second shaft end portion 10b protruding from the opening end of the external gear 22. The outer peripheral edge of the rotor disk 11 is a cylindrical portion 11a extending toward the wave gear reducer 4, and a rotor magnet 12 is attached to the outer peripheral side of the cylindrical portion 11a. The rotor magnet 12 is opposed to the stator coil 9 of the stator assembly 6 attached to the inner peripheral surface portion of the cylindrical body 5b of the motor case 5 with a certain gap.

On the other hand, in the wave gear reducer 4, the cup-shaped external gear 22 includes a cylindrical body 22 a that can be bent in the radial direction and a radial direction from the end of the body 22 a opposite to the motor 2. A disc-shaped diaphragm 22b extending inward, a rigid annular boss 22c integrally formed on the inner peripheral edge of the diaphragm 22b, and an opening end side opening on the motor 2 side in the body portion 22a. And external teeth 22d formed on the outer peripheral surface portion.

  In the input shaft portion 10 </ b> A of the rotor shaft 10 located inside the external gear 22, a rigid cam plate 23 a of the wave generator 23 is integrally formed at a portion on the motor side with respect to the main bearing 13. The rigid cam plate 23a has an outer peripheral surface with an elliptical contour, and a wave generator bearing 23b is mounted on the outer peripheral surface. The portion of the external teeth 22d on the open end side of the external gear 22 is bent elliptically by the wave generator 23 and partially meshed with the internal teeth 21d of the internal gear 21 arranged on the outer peripheral side thereof. ing.

  The reduction gear case 20 extends radially inward from the outer cylindrical portion 20a fixed to the inner peripheral surface of the cylindrical body portion 5b of the motor case 5 and the motor side end of the outer cylindrical portion 20a. The outer peripheral side disk part 20b, the inner peripheral side cylindrical part 20c extending from the inner peripheral part of the outer peripheral side disk part 20b to the motor side, and the motor side end of the inner peripheral side cylindrical part 20c extending radially inward. And an inner peripheral disk portion 20d.

  The rotor shaft 10 extends through the central portion of the inner peripheral disk portion 20d of the speed reducer case 20. Further, the inner circumferential side disk portion 20 d is located between the wave generator 23 and the rotor disk 11 of the motor 2. A space between the inner peripheral disk portion 20d and the rotor shaft 10 is sealed with an oil seal 26. This prevents the grease from leaking out from the wave gear reducer 4 side to the motor 2 and encoder 3 side.

  The internal gear 21 and the external gear 22 of the wave gear reducer 4 are supported in a relatively rotatable state via a cross roller bearing 27. The outer ring 28 of the cross roller bearing 27 is mounted and fixed on the inner side of the outer peripheral cylindrical portion 20a from the opening end 5c side of the outer peripheral cylindrical portion 20a of the speed reducer case 20. The inner ring 29 of the cross roller bearing 27 is integrally formed on the outer periphery of the output shaft 24 in this example. The output shaft 24 is formed with an inner peripheral edge portion 24a extending in a disc shape from the inner peripheral surface to the inside, and the inner peripheral edge portion 24a and the boss 22c of the external gear 22 are fixed coaxially.

  Next, FIG. 2 is an enlarged partial sectional view of the flat actuator 1. The main bearing 13 of the motor 2 disposed inside the cup-shaped external gear 22 will be described with reference to FIGS. 1 and 2. The main bearing 13 is mounted inside a cylindrical bearing housing 14 disposed inside the external gear 22. The bearing housing 14 includes a housing main body portion 14a to which the main bearing 13 is mounted, and a small-diameter mounting cylindrical portion 14b extending coaxially from an end portion of the housing main body portion 14a opposite to the motor 2. ing. An annular step 14c for retaining the outer ring is formed at the end of the housing main body 14a on the side of the mounting cylindrical portion 14b, and an annular step 14e for retaining the outer ring is formed at the other end. .

  The outer ring of the main bearing 13 is held between the inner end surfaces of the annular step portions 14c and 14e on both sides of the housing main body portion 14a in the bearing housing 14. Further, the inner ring of the main bearing 13 is held between a stepped surface 10 c for stopping the inner ring formed on the outer peripheral surface of the rotor shaft 10 and an annular bearing inner ring retainer 31.

  The bearing inner ring retainer 31 is held in contact with the inner ring of the main bearing 13 by a cylindrical nut 32 attached to the first shaft end 10 a of the rotor shaft 10. That is, the first shaft end portion 10a of the rotor shaft 10 is positioned inside the mounting cylindrical portion 14b of the bearing housing 14, and an annular bearing inner ring presser 31 is mounted thereon. A cylindrical nut 32 is screwed and fixed to the first shaft end 10 a, and the bearing inner ring retainer 31 is held in contact with the inner ring of the main bearing 13 by the cylindrical nut 32. A set screw 33 for preventing loosening is screwed into the cylindrical nut 32 and fixed.

  In this example, the fastening structure between the external gear 22 and the output shaft 24 is constituted by the bearing housing 14 and the nut 15. As shown in FIG. 2, the mounting cylindrical portion 14 b of the bearing housing 14 extends to the output side through the center opening of the boss 22 c of the external gear 22 and the center opening of the inner peripheral edge portion 24 a of the output shaft 24. . A portion of the mounting cylindrical portion 14b that protrudes from the center opening of the inner peripheral edge portion 24a opposite to the motor 2 is a bolt portion 14d in which a male screw is cut on the outer peripheral surface. A nut 15 is fastened and fixed to the bolt portion 14d from the output side. Thereby, the inner peripheral edge 24 a of the output shaft 24 and the boss 22 c of the external gear 22 are sandwiched between the bearing housing 14 and the nut 15 and fastened and fixed.

  In the flat actuator 1 having this configuration, when the motor 2 is driven and the rotor shaft 10 is rotated, the wave generator 23 of the wave gear reducer 4 formed integrally therewith is rotated. When the wave generator 23 rotates, the meshing positions of the external gear 22 with respect to the internal gear 21 (positions at both ends of the elliptical long axis) move in the circumferential direction. For example, since the number of teeth of the external gear 22 is two less than that of the internal gear 21, the external gear 22 is relative to the internal gear 21 by a difference in the number of teeth while the wave generator 23 rotates once. Rotate. Since the internal gear 21 is fixed, the reduced speed rotation (actuator output) is taken out from the output shaft 24 of the external gear 22.

DESCRIPTION OF SYMBOLS 1 Flat actuator 1a Axis 2 Motor 3 Encoder 4 Wave gear reducer 5 Motor case 5a End plate part 5b Cylindrical trunk | drum 5c Open end 6 Stator assembly 7 Rotor assembly 8 Stator core 9 Stator coil 10 Rotor shaft 10a 1st shaft end part 10b Second shaft end portion 10c Step surface 10A Input shaft portion 11 Rotor disk 11a Cylindrical portion 12 Rotor magnet 13 Main bearing 14 Bearing housing 14a Housing main body portion 14b Mounting cylindrical portion 14c Annular step portion 14d Bolt portion 14e Annular step portion 15 Nut 20 Reduction gear case 20a Outer peripheral side cylindrical part 20b Outer peripheral side disk part 20c Inner peripheral side cylindrical part 20d Inner peripheral side disk part 21 Internal gear 21d Internal gear 22 External gear 22a Body 22b Diaphragm 22c Boss 22d External gear 23 Wave motion Generator 23a Rigid cam plate 2 3b Wave generator bearing 24 Output shaft 24a Inner peripheral edge 26 Oil seal 27 Cross roller bearing 28 Outer ring 29 Inner ring 31 Bearing inner ring retainer 32 Cylindrical nut 33 Set screw

Claims (3)

A motor,
An encoder,
A main bearing for supporting the rotor shaft of the rotor of the motor in a cantilever state;
A wave gear reducer that decelerates the motor rotation taken from the rotor shaft;
Have
The wave gear reducer includes a cup-shaped flexible external gear disposed coaxially with the rotor shaft,
The main bearing is disposed inside the external gear,
The rotor shaft has a portion on the side of one first shaft end located inside the external gear and is supported by the main bearing, and a portion on the side of the other second shaft end of the external gear. Protrudes from the open end to the outside,
The flat actuator according to claim 1, wherein the encoder is attached to an end of the second shaft of the rotor shaft. In claim 1,
A wave generator of the wave gear reducer is attached to the side of the first shaft end on the shaft portion between the main bearing and the encoder in the rotor shaft, and on the side of the second shaft end, A rotor disk with a rotor magnet fixed to the outer periphery of the rotor is attached,
The wave generator and the rotor disk are partitioned by a reducer case,
A flat actuator in which an oil seal seals between the speed reducer case and the rotor shaft extending through the speed reducer case. In claim 1 or 2,
The main bearing is a flat actuator which is a combination angular contact ball bearing.