JP2017103951A - Actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an actuator that can mount various sensors while suppressing increase in dimension.SOLUTION: In an actuator 1, a hollow type wave gear device 3 that has a configuration in which a wave generator 13 is arranged at an outer peripheral side is arranged in an inner rotor type motor 2, and an output shaft 4 for extracting output rotation of the wave gear device 3 is arranged at a first shaft end part 7a of a hollow fixed shaft 7. The rotation of the output shaft 4 can be detected by an output shaft sensor 5 inserted into a hollow part 33 from the first shaft end part 7a side of the hollow fixed shaft 7. Since the hollow part 33 is used as an installation space for the output shaft sensor 5, increase in shaft length of the actuator 1 can be suppressed compared with a case where the output shaft sensor 5 is juxtaposed in a direction of an axis line 1a.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an actuator having a configuration in which a hollow wave gear device is coaxially assembled inside an inner rotor type motor.

  As this type of actuator, there is a drive unit with a reduction gear described in FIG. The drive device includes a motor and a wave gear device, and the wave gear device includes a wave generator, a flexible internal gear arranged inside the wave generator, and a rigid external gear arranged inside the wave generator, A plug having an elliptical inner peripheral surface of the wave generator is integrally formed with the motor rotor.

  The motor rotor includes a cylindrical portion that extends to one side in the axial direction, and a motor encoder (input shaft encoder) that detects motor rotation (input rotation of the wave gear device) is disposed on the outer periphery of the cylindrical portion.

Japanese Patent No. 4787753

  In the actuator of this configuration, when detecting the output rotation, the boss portion of the flexible internal gear which is the output element of the wave gear device is extended in the axial direction, and the output shaft encoder is arranged on the outer peripheral portion thereof. The In this configuration, the input shaft encoder and the output shaft encoder are arranged in the axial direction of the actuator, and the dimension in the axial direction increases. In some cases, a torque sensor is mounted on the actuator to detect the transmission torque. Even in this case, the size of the apparatus increases in order to secure the mounting place of the torque sensor.

  On the other hand, when the actuator having this configuration is miniaturized, there may be a layout in which the lubrication portion of the wave gear device and the sensor portion such as the input shaft encoder are close to each other. In such a case, it is necessary to take measures so that the lubricant leaking from the lubrication portion does not enter the sensor portion.

  In view of these points, an object of the present invention is to provide an actuator capable of mounting various sensors while suppressing an increase in apparatus size.

  Another object of the present invention is to provide an actuator that can be mounted with various sensors while suppressing an increase in device dimensions, and that can prevent lubricant from entering the sensor side from the wave gear device.

In order to solve the above problems, the actuator of the present invention is
A cylindrical housing;
A hollow fixed shaft disposed coaxially in the central portion of the housing;
A disc-shaped output shaft that is disposed on the first shaft end portion side that is one shaft end portion in the axial direction of the hollow fixed shaft, and is rotatably supported via a main bearing with respect to the housing;
A disc-shaped end plate disposed on the other second shaft end side of the hollow fixed shaft, and fixed to the hollow fixed shaft and the housing;
An inner rotor type motor disposed in an annular space between the housing and the hollow shaft formed between the end plate and the output shaft;
A wave gear device that is disposed inside the motor in the annular space, and decelerates the rotation of the motor and transmits it to the output shaft;
An output shaft sensor for detecting rotation of the output shaft;
With
The output shaft sensor is disposed in a portion on the first shaft end side in the hollow portion of the hollow fixed shaft, and an encoder plate that rotates integrally with the output shaft, and a detection unit that detects rotation of the encode plate; With
The encoding plate is attached to a mounting plate facing the second shaft end portion of the hollow fixed shaft from the outside in the axial direction, and the mounting plate is fixed to the output shaft. .

  In the actuator of the present invention, a hollow wave gear device having a configuration in which a wave generator is arranged on the outer peripheral side is arranged inside the inner rotor type motor, and an output shaft for taking out the output rotation of the wave gear device is provided. The hollow fixed shaft is disposed on the first shaft end side. With this configuration, the rotation of the output shaft can be detected by the output shaft sensor inserted into the hollow portion from the first shaft end portion side of the hollow fixed shaft. Since the inside of the hollow portion is used as an installation space for the output shaft sensor, an increase in the axial length of the actuator can be suppressed as compared with the case where the output shaft sensors are arranged in the axial direction.

  In the actuator according to the present invention, the motor includes an annular motor stator fixed inside a cylindrical housing, and a motor rotor arranged coaxially inside the motor stator. The wave gear device includes a wave generator coaxially fixed to the inside of the motor rotor, and a flexure disposed coaxially to the inside of the wave generator and bent in an elliptical shape by the wave generator. An internal gear and a rigid external gear that is coaxially disposed inside the flexible internal gear and that partially meshes with the flexible internal gear bent in an elliptical shape.

  The rigid external gear is preferably composed of a hollow fixed shaft and external teeth formed on the outer peripheral surface of the hollow shaft. The flexible internal gear includes a flexible cylindrical body portion formed with internal teeth capable of meshing with the external teeth, and an end on the first shaft end portion side of the cylindrical body portion. A diaphragm having a diaphragm extending outward in the radial direction, and a top-hat-shaped one provided with a rigid disc-shaped boss continuously formed on the outer peripheral edge of the diaphragm. A boss is fixed to the output shaft.

  In this case, it is desirable that the first oil seal is sealed between the first shaft end portion of the hollow fixed shaft and the output shaft so that the lubricant does not leak outside from the wave gear device.

  In this invention, the torque sensor for detecting the transmission torque of a wave gear apparatus can be arrange | positioned in the outer peripheral surface part by the side of the said 2nd shaft end part of the said hollow fixed shaft. In this case, the second oil seal disposed between the hollow fixed shaft and the wave generator seals between the torque sensor and the meshing position of the flexible internal gear and the rigid external gear. It is desirable.

  Since the transmission torque acting on the output side flexible internal gear acts on the fixed-side rigid external gear, the transmission torque can be detected by arranging a torque sensor on the hollow fixed shaft of the rigid external gear. Conventionally, a detection element such as a strain gauge is attached to the flexible internal gear to detect the transmission torque. However, since the detection element is repeatedly bent together with the flexible internal gear, it is preferable in terms of durability and the like. Absent. The torque sensor of the present invention is superior in durability and the like since the torque sensor can be disposed on the rigid internal gear.

  Further, since the second oil seal prevents the lubricating oil from entering the side of the torque sensor from the meshing portion of the teeth, the lubricating oil or the like does not adhere to the torque sensor so that a problem does not occur.

  Next, an input shaft sensor for detecting the rotation of the wave generator (and hence the rotation of the motor rotor) can be disposed at the outer peripheral side of the wave generator on the second shaft end side.

  On the other hand, a second actuator including a second motor and a second wave gear device can be incorporated using the space in the hollow portion of the hollow fixed shaft. In this case, by forming internal teeth on the inner peripheral surface of the hollow fixed shaft, the hollow fixed shaft is used as a rigid internal gear, and a flexible external gear is arranged on the inner side, and waves are generated on the inner side. The wave generator is rotated by a second motor. Thereby, the second output rotation can be taken out from the flexible external gear.

It is a schematic longitudinal cross-sectional view which shows the actuator to which this invention is applied. It is explanatory drawing which shows another example of the actuator to which this invention is applied.

  FIG. 1 is a schematic longitudinal sectional view showing an actuator according to the present embodiment. The actuator 1 includes an inner rotor type motor 2, a wave gear device 3 that decelerates and outputs the rotation of the motor 2, an output shaft 4 that outputs an output rotation of the wave gear device 3 to the outside, and a rotation of the output shaft 4. And an output shaft sensor 5 for detecting.

  More specifically, the actuator 1 includes a cylindrical housing 6 and a hollow fixed shaft 7 disposed coaxially in the center of the housing 6. A disc-shaped output shaft 4 is arranged on the first shaft end portion 7a side which is one shaft end portion in the direction of the axis 1a of the hollow fixed shaft 7, and a disc-shaped output shaft 4 is arranged on the opposite second shaft end portion 7b. The end plate 8 is arranged. A motor 2 and a wave gear device 3 are incorporated in an annular space formed between the housing 6 and the hollow fixed shaft 7 between the output shaft 4 and the end plate 8.

  The output shaft 4 is formed with a shaft hole 4a at the center and orthogonal to the axis 1a. The output shaft 4 is fixed to the end of the housing 6 via a cross roller bearing 9 which is a main bearing. The first shaft end 7 a of the hollow fixed shaft 7 is coaxially inserted into the shaft hole 4 a of the output shaft 4. In this example, the inner ring of the cross roller bearing 9 is formed integrally with the output shaft 4, and the inner ring and the output shaft 4 are made of a single component. The output shaft 4 is connected to a driven member (not shown). The outer ring 9 a of the cross roller bearing 9 is fixed to the end of the housing 6. A portion on the outer peripheral side of the outer ring 9a is a mounting flange fixed to another member (not shown).

  The end plate 8 on the second shaft end portion 7b side of the hollow fixed shaft 7 is also formed with a shaft hole 8a and is arranged in a state orthogonal to the axis 1a. The inner peripheral edge of the end plate 8 is fixed to the end surface of the hollow fixed shaft 7, and the outer peripheral edge of the end plate 8 is a cylindrical portion 8 b bent at a right angle, and the end of the cylindrical portion 8 b is the side of the housing 6. It is fixed to.

  The inner rotor type motor 2 includes an annular motor stator 11 fixed to a circular inner peripheral surface of a housing 6, and a motor rotor 12 disposed coaxially inside the motor stator 11. The motor stator 11 is composed of a stator core and a stator coil wound around salient poles formed on the stator core, and the motor rotor 12 is composed of a rotor magnet made of a permanent magnet.

  The wave gear device 3 includes a cylindrical wave generator 13 disposed inside the motor rotor 12, a flexible internal gear 14 disposed coaxially on the inside, and a rigid external gear 15 disposed coaxially on the inside. I have. The wave generator 13 includes a cylindrical rigid plug 16 and a bearing 17 attached to the elliptical inner peripheral surface 16a. The rigid plug 16 is fixed to the inner peripheral surface of the motor rotor 12 and is driven to rotate by the motor 2.

  The flexible internal gear 14 includes a flexible cylindrical body 18, a diaphragm 19 that extends radially outward from the end toward the first shaft end 7 a of the cylindrical body 18, and the diaphragm 19 is a top-hat-shaped one provided with a rigid disc-shaped boss 20 continuously formed on the outer peripheral edge of 19. A boss 20 is fixed to the output shaft 4. Inner teeth 21 are formed on the inner peripheral surface portion of the end of the cylindrical body portion 18 on the second shaft end portion 7b side. A portion of the cylindrical body portion 18 where the internal teeth 21 are formed is bent in an elliptical shape by the wave generator 13.

  In this example, the rigid external gear 15 includes a hollow fixed shaft 7 and external teeth 22 formed on the outer peripheral surface of the hollow fixed shaft 7. The internal teeth 21 of the flexible internal gear 14 that are bent elliptically from the outside by the wave generator 13 partially mesh with the external teeth 22 of the rigid external gear 15.

  The rigid plug 16 of the wave generator 13 is rotatably supported by ball bearings 23 and 24 at both ends in the direction of the axis 1a. One ball bearing 23 is supported by a bearing receiver 25 fixed to the output shaft 4. The other ball bearing 24 is supported by a bearing receiver 26 fastened and fixed to the housing 6 and the end plate 8 while being sandwiched between them. The bearing receiver 26 is a disk-shaped member arranged in a state orthogonal to the axis 1a.

  Here, a gap between the inner peripheral surface of the shaft hole 4a of the output shaft 4 and the outer peripheral surface of the first shaft end portion 7a of the hollow fixed shaft 7 is sealed by a first oil seal 31 disposed therebetween. ing. On the second shaft end portion 7b side of the hollow fixed shaft 7, a gap between the rigid plug 16 of the wave generator 13 and the second shaft end portion 7b is a second oil seal disposed between them. 32 is sealed.

  Next, the output shaft sensor 5 is disposed at a site on the first shaft end portion 7 a side in the hollow portion 33 of the hollow fixed shaft 7. The output shaft sensor 5 includes an encode plate 34 that rotates integrally with the output shaft 4 and a detection unit 35 that detects the rotation of the encode plate 34. The encoding plate 34 is attached to an attachment disk 36 that is opposed to the first shaft end 7a of the hollow fixed shaft 7 from the outside in the direction of the axis 1a. The attachment disk 36 is arranged in a state of sealing the shaft hole 4 a of the output shaft 4.

  A torque sensor 40 for detecting the transmission torque of the wave gear device 3 is disposed on the outer peripheral surface portion of the hollow fixed shaft 7 on the second shaft end portion 7b side. As described above, the second oil seal 32 is disposed between the hollow fixed shaft 7 and the rigid plug 16 of the wave generator 13. The second oil seal 32 seals between the torque sensor 40 and the meshing position of the flexible internal gear 14 and the rigid external gear 15.

  Further, in this example, the rigid plug 16 of the wave generator 13 is formed with a cylindrical portion 16b extending toward the second shaft end portion 7b. The cylindrical portion 16 b extends between the bearing receiver 26 and the end plate 8. An input shaft encoder 41 that detects the rotation (input rotation) of the wave generator 13 is disposed on the outer peripheral side of the cylindrical portion 16b.

  In the actuator 1 configured as described above, a hollow wave gear device 3 having a configuration in which the wave generator 13 is disposed on the outer peripheral side is disposed inside the inner rotor type motor 2. An output shaft 4 for taking out the output rotation is arranged on the first shaft end 7 a side of the hollow fixed shaft 7. With this configuration, the rotation of the output shaft 4 can be detected by the output shaft sensor 5 inserted into the hollow portion 33 from the first shaft end 7 a side of the hollow fixed shaft 7. Since the inside of the hollow portion 33 is used as an installation space for the output shaft sensor 5, an increase in the axial length of the actuator 1 can be suppressed as compared with the case where the output shaft sensor 5 is arranged in the direction of the axis 1a.

  Further, the first oil seal 31 seals between the first shaft end 7 a of the hollow fixed shaft 7 and the output shaft 4 so that the lubricant does not leak out from the wave gear device 3. Accordingly, it is possible to prevent the leaked lubricant or the like from flowing around the output shaft sensor 5 in the hollow portion 33. Similarly, the second oil seal 32 can prevent the lubricant or the like from leaking to the torque sensor 40 or the input shaft encoder 41 side.

  Further, a torque sensor 40 is disposed on the fixed-side rigid external gear 15, that is, the hollow fixed shaft 7. When detecting a transmission torque by attaching a detection element such as a strain gauge to the flexible internal gear 14, the detection element is repeatedly bent together with the flexible internal gear 14, which is not preferable in terms of durability. In this example, such an adverse effect can be avoided, and a torque detection mechanism that is superior in durability and the like can be realized.

(Other embodiments)
FIG. 2 is an explanatory view showing a modification of the actuator 1 described above. The actuator shown in this figure is a biaxial actuator 1A, and a second actuator 51 including a second motor 52 and a second wave gear device 53 is incorporated using the space in the hollow portion 33 of the hollow fixed shaft 7. ing.

  For example, the hollow fixed shaft 7 is used as a rigid internal gear by forming the internal teeth 54 on the inner peripheral surface of the hollow fixed shaft 7. A cup-shaped flexible external gear 55 is disposed on the inner side, and a wave generator 56 is disposed on the inner side. The wave generator 56 is rotationally driven by a second motor 52 disposed in the hollow portion 33. Thereby, the second output rotation can be taken out from the second output shaft 57 attached to the flexible external gear 55. According to this configuration, a biaxial actuator can be configured without increasing the size.

DESCRIPTION OF SYMBOLS 1 Actuator 1A 2 axis | shaft actuator 1a Axis 2 Motor 3 Wave gear apparatus 4 Output shaft 4a Shaft hole 5 Output shaft sensor 6 Housing 7 Hollow fixed shaft 7a 1st shaft end part 7b 2nd shaft end part 8 End plate 8a Shaft hole 8b Cylindrical Part 9 Cross roller bearing 9a Outer ring 11 Motor stator 12 Motor rotor 13 Wave generator 14 Flexible internal gear 15 Rigid external gear 16 Rigid plug 16a Elliptical inner peripheral surface 16b Cylindrical part 17 Bearing 18 Cylindrical body 19 Diaphragm 20 Boss 21 Internal teeth 22 External teeth 23, 24 Ball bearings 25, 26 Bearing receiver 31 First oil seal 32 Second oil seal 33 Hollow portion 34 Encoding plate 35 Detection portion 36 Mounting disc 40 Torque sensor 41 Input shaft encoder 51 Second actuator 52 Second motor 53 Second wave gear device 54 Internal teeth 5 flexible external gear 56 wave generator 57 the second output shaft

Claims (6)

A cylindrical housing;
A hollow fixed shaft disposed coaxially in the central portion of the housing;
A disc-shaped output shaft that is disposed on the first shaft end portion side that is one shaft end portion in the axial direction of the hollow fixed shaft, and is rotatably supported via a main bearing with respect to the housing;
A disc-shaped end plate disposed on the other second shaft end side of the hollow fixed shaft, and fixed to the hollow fixed shaft and the housing;
An inner rotor type motor disposed in an annular space between the housing and the hollow fixed shaft formed between the end plate and the output shaft;
A wave gear device that is disposed inside the motor in the annular space, and decelerates the rotation of the motor and transmits it to the output shaft;
An output shaft sensor for detecting rotation of the output shaft;
With
The output shaft sensor is disposed in a portion on the first shaft end side in the hollow portion of the hollow fixed shaft, and an encoder plate that rotates integrally with the output shaft, and a detection unit that detects rotation of the encode plate; With
The encoding plate is attached to a mounting plate facing the second shaft end portion of the hollow fixed shaft from the outside in the axial direction, and the mounting plate is fixed to the output shaft. The motor is
An annular motor stator fixed inside a cylindrical housing;
A motor rotor disposed coaxially inside the motor stator;
With
The wave gear device is
A wave generator fixed coaxially inside the motor rotor;
A flexible internal gear coaxially disposed inside the wave generator and bent in an elliptical shape by the wave generator;
A rigid external gear coaxially disposed inside the flexible internal gear and partially meshed with the flexible internal gear bent in an elliptical shape;
With
The rigid external gear is composed of a hollow fixed shaft and external teeth formed on the outer peripheral surface of the hollow shaft,
The flexible internal gear includes a flexible cylindrical body portion in which internal teeth capable of meshing with the external teeth are formed, and a radius from the end toward the second shaft end portion in the cylindrical body portion. A top hat with a diaphragm extending outward in the direction and a rigid disc-shaped boss formed continuously on the outer periphery of the diaphragm;
The actuator according to claim 1, wherein the boss is fixed to the output shaft.   The actuator according to claim 2, wherein a gap between the first shaft end portion of the hollow fixed shaft and the output shaft is sealed by a first oil seal. A torque sensor for detecting transmission torque is disposed on the outer peripheral surface portion of the hollow fixed shaft on the side of the second shaft end,
The space between the torque sensor and the meshing position of the flexible internal gear and the rigid external gear is sealed by a second oil seal disposed between the hollow fixed shaft and the wave generator. Actuator.   5. The actuator according to claim 4, wherein an input shaft sensor that detects rotation of the wave generator is disposed at a portion of the wave generator on the outer peripheral side on the second shaft end side. A second actuator including a second motor and a second wave gear device is incorporated in the hollow portion of the hollow fixed shaft;
The second wave gear device is mounted on a rigid internal gear formed by forming internal teeth on an inner peripheral surface of the hollow fixed shaft, a flexible external gear disposed on the inner side, and an inner side. A wave generator,
2. The actuator according to claim 1, wherein the wave generator is rotationally driven by the second motor and can extract a second output rotation from the flexible external gear.

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