JP6656755B2 - Flat actuator - Google Patents

Description

  The present invention relates to a flat actuator including 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 center axis.

  The output portion of the hollow motor shaft of the AC servomotor extends through the front end plate of the motor housing and into the cup-shaped flexible external gear 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 mounted on the opposite side of the hollow motor shaft. The hollow motor shaft is supported by a front main bearing attached to a front end plate of the motor housing and a rear main bearing on the encoder side at a fixed interval in the axial direction in a double-supported state.

JP 2014-206265 A

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

  In addition, it is necessary to provide a mounting portion for a wave generator by extending a front end portion on the output side of the motor shaft to the side of the wave gear reducer, and provide a mounting portion for an encoder by extending a rear end portion to the rear side. . Therefore, the shaft length of the motor shaft tends to be long.

  A long motor shaft needs to be supported in a double-supported state by a front main bearing and a rear main bearing which are spaced apart in the axial direction in order to secure the supporting rigidity. For this reason, a space for arranging the bearing before and after in the axial direction is required. Also from this point, the axial length of the actuator tends to be long.

  If a sufficient installation space cannot be secured in the axial direction, it may be difficult to incorporate an actuator having a long shaft length into the housing.

  In view of the above, 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 connected in an axial direction.

In order to solve the above problems, the flat actuator of the present invention
Motor and
An encoder for detecting a rotation state of the motor;
A main bearing such as a combination angular contact ball bearing that supports the rotor shaft of the motor in a cantilever state,
A wave gear reducer for reducing the rotation of the motor taken out of the rotor shaft,
Has,
The wave gear reducer includes a cup-shaped flexible external gear arranged coaxially with the rotor shaft,
The main bearing is disposed inside the external gear,
The rotor shaft has a first shaft end side portion located inside the external gear and supported by the main bearing, and a second second shaft end side portion of the external gear. It protrudes outside from the open end,
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 by utilizing the internal space of the external gear having a cup shape, the rotor shaft is supported by the main bearing in a cantilever state, and the rear end side of the rotor shaft (encoder) Side of the second shaft end) can be in a free state.

  Conventionally, a portion of a rotor shaft protruding outside from an external gear of a wave gear speed reducer is supported in a double-supported state by a pair of main bearings arranged at a predetermined interval along the axial direction. The second shaft end side of the rotor shaft on the encoder side cannot be set in a free state.

  In the present invention, the rear end side of the rotor shaft can be made free, so that a space for installing a pair of main bearings can be omitted on the side of the motor (encoder), and the shaft length of the rotor shaft can be shortened by that much. it can. Further, since the rotor shaft can be shortened, if a bearing having a high load capacity such as a combination angular contact ball bearing is used, the rotor shaft can be supported in a cantilever state with sufficient supporting rigidity. Further, since the main bearing of the rotor shaft does not exist on the encoder side, there is no need to arrange a part for preventing the scattering of bearing lubricating oil for lubricating the main bearing. That is, it is not necessary to arrange a dedicated member for preventing 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 in the past.

  Further, in the present invention, the rear end side of the rotor shaft can be set in a free state, and the main bearing and the holding mechanism of the main bearing are not required on the encoder side. And assemblability can be improved. Therefore, according to the present invention, a flat actuator can be realized, and the processing cost and the assembly cost 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 a shaft portion of the rotor shaft between the main bearing and the encoder, on a side of the first shaft end, A rotor disk having a rotor magnet fixed to an outer peripheral portion is attached to an end of the second shaft, and the wave generator and the rotor disk are partitioned by a speed reducer case. The space between the rotor shaft and the rotor shaft extending through the case can be sealed by an oil seal.

  According to this configuration, the motor and the wave gear reducer are partitioned by the reducer case and the oil seal. The grease can be prevented from leaking from the wave gear reducer to the motor. The adverse effect that grease leaking to the motor side is scattered by the rotation of the rotor to the side of the encoder arranged adjacently and adheres to the encoder can be prevented.

1 is a schematic longitudinal sectional view showing a flat actuator to which the present invention is applied. FIG. 2 is a partially enlarged cross-sectional view of the flat actuator of FIG. 1.

  An embodiment of a flat actuator according to the present invention will be described below with reference to the drawings.

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

  The motor 2 includes a stator assembly 6 and a rotor assembly 7 coaxially incorporated in a motor case 5 having an end plate 5a and a cylindrical body 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 attached to an outer peripheral portion of the rotor disk 11.

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

  In this example, a combined 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 the combination angular contact ball bearing.

  The structure of each part will be specifically described. First, the rotor shaft 10 of the motor 2 is arranged along the center axis 1 a of the flat actuator 1. The rotor shaft 10 has a portion on the output side of the first shaft end 10 a located inside the external gear 22, and is rotatably supported by the main bearing 13. A portion on the side of the second shaft end 10 b, which is the other non-output end (rear end) of the rotor shaft 10, protrudes from the open end of the external gear 22. The second shaft end 10b protrudes outward from an end plate portion 5a on the rear end side of the motor case 5, and the rotation-side portion of the encoder 3 is coaxially fixed to the protruding portion.

  A rotor disk 11 is coaxially fixed to the shaft portion of the rotor shaft 10 on the side of the second shaft end 10 b protruding from the open 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 mounted on the outer peripheral side of the cylindrical portion 11a. The rotor magnet 12 faces the stator coil 9 of the stator assembly 6 attached to the inner peripheral surface 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 has a cylindrical body 22 a that can be bent in the radial direction and a radially extending end of the body 22 a from the end opposite to the motor 2. A disk-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 of the body 22a that is open to the motor 2 side. External teeth 22d formed on the outer peripheral surface portion.

  In the input shaft portion 10A of the rotor shaft 10 located inside the external gear 22, a rigid cam plate 23a of a wave generator 23 is integrally formed at a portion of the input shaft portion 10A on the motor side with respect to the main bearing 13. The rigid cam plate 23a has an outer peripheral surface having 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 into an elliptical shape by the wave generator 23, and partially meshes with the internal teeth 21d of the internal gear 21 disposed on the outer peripheral side thereof. ing.

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

  The rotor shaft 10 extends through the center portion of the inner peripheral disk portion 20d of the speed reducer case 20. The inner disk 20 d is located between the wave generator 23 and the rotor disk 11 of the motor 2. An oil seal 26 seals between the inner peripheral disk portion 20d and the rotor shaft 10. This prevents grease from leaking from the side of the wave gear reducer 4 to the side of the motor 2 and the encoder 3.

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

  Next, FIG. 2 is an enlarged partial cross-sectional view of the flat actuator 1. 1 and 2, the main bearing 13 of the motor 2 disposed inside the cup-shaped external gear 22 will be described. The main bearing 13 is mounted inside a cylindrical bearing housing 14 arranged inside the external gear 22. The bearing housing 14 includes a housing body 14a on which the main bearing 13 is mounted, and a small-diameter mounting cylindrical portion 14b coaxially extending from an end of the housing body 14a opposite to the motor 2. ing. An annular step 14c for stopping the outer ring is formed at one end of the housing body 14a on the side of the mounting cylinder 14b, and an annular step 14e for stopping the outer ring is also 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. The inner ring of the main bearing 13 is held between an inner ring stopper step surface 10 c formed on the outer peripheral surface of the rotor shaft 10 and an annular bearing inner ring retainer 31.

  The bearing inner ring presser 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 10a of the rotor shaft 10 is located inside the mounting cylindrical portion 14b of the bearing housing 14, and the annular bearing inner ring retainer 31 is mounted here. A cylindrical nut 32 is screwed into and fixed to the first shaft end 10a, and the cylindrical nut 32 holds the bearing inner ring presser 31 in contact with the inner ring of the main bearing 13. 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 14b of the bearing housing 14 extends to the output side through the center opening of the boss 22c of the external gear 22 and the center opening of the inner peripheral edge 24a of the output shaft 24. . A portion of the mounting cylindrical portion 14b protruding from the center opening of the inner peripheral edge portion 24a opposite to the motor 2 is a bolt portion 14d having a male screw cut on the outer peripheral surface. A nut 15 is fastened and fixed to the bolt portion 14d from the output side. Thus, the inner peripheral edge 24a of the output shaft 24 and the boss 22c of the external gear 22 are fastened and fixed between the bearing housing 14 and the nut 15.

  In the flat actuator 1 having this configuration, when the motor 2 is driven and the rotor shaft 10 rotates, the wave generator 23 of the wave gear reducer 4 integrally formed therewith rotates. When the wave generator 23 rotates, the meshing position of the external gear 22 with respect to the internal gear 21 (positions at both ends of the long axis of the elliptical shape) moves in the circumferential direction. For example, since the number of teeth of the external gear 22 is smaller than that of the internal gear 21 by two, the external gear 22 is relative to the internal gear 21 by a tooth number difference while the wave generator 23 makes one rotation. Rotate. Since the internal gear 21 is fixed, the reduced rotation (actuator output) is extracted 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 5b Cylindrical body 5c Open end 6 Stator assembly 7 Rotor assembly 8 Stator core 9 Stator coil 10 Rotor shaft 10a First shaft end 10b Second shaft end 10c Stepped surface 10A Input shaft 11 Rotor disk 11a Cylindrical portion 12 Rotor magnet 13 Main bearing 14 Bearing housing 14a Housing body 14b Mounting cylindrical portion 14c Annular step 14d Bolt portion 14e Annular step 15 Nut 20 Reducer case 20a Outer side cylindrical part 20b Outer side disk part 20c Inner side cylindrical part 20d Inner side disk part 21 Internal gear 21d Internal tooth 22 External tooth gear 22a Body 22b Diaphragm 22c Boss 22d External tooth 23 Wave 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 holder 32 Cylindrical nut 33 Set screw

Claims (4)

Motor and
An encoder,
A main bearing that supports the rotor shaft of the motor rotor in a cantilever state,
A wave gear reducer for reducing the rotation of the motor taken out of the rotor shaft,
An output shaft that outputs reduced speed rotation of the wave gear reducer,
Has,
The wave gear reducer includes a cup-shaped flexible external gear disposed coaxially with the rotor shaft, the external gear having a cylindrical body that can be bent in a radial direction, A disk-shaped diaphragm extending inward in the radial direction from the end opposite to the motor in the portion, and a rigid annular boss integrally formed on the inner peripheral edge of the diaphragm,
It said main bearing is mounted on the inside of the barrel cylindrical bearing housing arranged in the interior of the external gear,
The rotor shaft has a first shaft end side portion located inside the external gear and supported by the main bearing, and a second second shaft end side portion of the external gear. It protrudes outside from the open end,
The encoder is attached to the second shaft end of the rotor shaft ,
The bearing housing has a cylindrical housing main body on which the main bearing is mounted, and a smaller-diameter mounting than the housing main body extending coaxially from an end of the housing main body opposite to the motor. And a cylindrical part for
The mounting cylindrical portion extends through a center opening formed in the boss of the external gear and a center opening formed in the output shaft toward an output side opposite to the motor,
In the mounting cylindrical portion, a portion protruding from the center opening of the output shaft to the output side is a bolt portion having an external thread cut on an outer peripheral surface thereof,
A nut is fastened and fixed to the bolt portion from the output side,
A flat actuator in which the output shaft and the boss are sandwiched and fixed between the bearing housing and the nut . The bearing housing is formed at an end of the housing main body on the side of the mounting cylindrical portion for stopping an outer ring, and is formed at an end of the housing main body opposite to the mounting cylindrical portion. With an annular step for stopping the outer ring,
An outer ring of the main bearing is held between inner end surfaces of the annular step portions on both sides of the housing body in the bearing housing,
An inner ring of the main bearing is held between a step surface for inner ring stopper formed on an outer peripheral surface of the rotor shaft and an annular bearing inner ring retainer,
The bearing inner ring presser is held in contact with the inner ring of the main bearing by a cylindrical nut attached to the first shaft end of the rotor shaft from the output side,
The flat actuator according to claim 1, wherein the cylindrical nut is screwed and fixed to an end of the first shaft from an opening end on the output side of the mounting cylindrical portion of the bearing housing. On the shaft portion between the main bearing and the encoder in the rotor shaft, a wave generator of the wave gear reducer is mounted on the side of the first shaft end, and on the side of the second shaft end, A rotor disk to which a rotor magnet is fixed is attached to an outer peripheral portion of the rotor,
The wave generator and the rotor disk are partitioned by a speed reducer case,
The flat actuator according to claim 1, wherein a space between the speed reducer case and the rotor shaft extending through the speed reducer case is sealed by an oil seal.   The flat actuator according to claim 1, wherein the main bearing is a combination angular contact ball bearing.