CN114641381A

CN114641381A - Drive device

Info

Publication number: CN114641381A
Application number: CN202080076995.3A
Authority: CN
Inventors: 田村光扩
Original assignee: Sumitomo Heavy Industries Ltd
Current assignee: Sumitomo Heavy Industries Ltd
Priority date: 2019-11-11
Filing date: 2020-09-18
Publication date: 2022-06-17
Also published as: JP2021076191A; WO2021095362A1; DE112020005575T5; JP7321894B2

Abstract

The invention provides a driving device which can detect torque output from the driving device with high precision and can restrain the component cost for detecting the torque to be low. A drive device (1) is provided with input members (13, 15a) for inputting torque, a speed reduction mechanism (15), an output member (16) for transmitting rotation after speed reduction, an input-side rotation detector (18) for detecting rotation of the input member, and an output-side rotation detector (19) for detecting rotation of the output member. The Young's modulus of the portions (15d, 15e) of the speed reduction mechanism (15) and the output member (16) where the Young's modulus is smallest is smaller than that of the portions of the input members (13, 15a) where the Young's modulus is smallest, and the resolution of the output-side rotation detector (19) is lower than that of the input-side rotation detector (18).

Description

Drive device

Technical Field

The present invention relates to a drive device.

Background

Patent document 1 discloses a robot device having a joint rotationally driven via a rotation motor and a reduction gear. The robot device of patent document 1 includes: an input-side encoder for generating a pulse signal by minute rotation of the rotary motor; a rectangular wave generating unit that generates a pulse signal according to a rotation angle of the joint; the output side encoder is arranged on the output side of the speed reducer, and pulse signals are generated when the joint rotates by a small angle each time; and a control unit for calculating the torsion angle of the joint based on the pulse signals.

Prior art documents

Patent document

Patent document 1: japanese patent laid-open No. 2014-65097

Disclosure of Invention

Technical problem to be solved by the invention

In a drive device that amplifies an input torque via a speed reducer and outputs the amplified torque, a strain is generated between an input member and an output member in accordance with the torque. If a strain sensor is used or a high-resolution encoder is used to detect strain, the component cost of the apparatus increases.

The invention aims to provide a driving device which can reduce the cost of components for detecting the torque of the driving device.

Means for solving the technical problem

A driving device according to the present invention includes an input member to which torque is input, a speed reduction mechanism that reduces a speed of rotation of the input member, and an output member to which the rotation reduced by the speed reduction mechanism is transmitted, and further includes:

an input-side rotation detector for detecting rotation of the input member; and

an output-side rotation detector for detecting rotation of the output member,

in the case where a portion of the input member where the young's modulus between the input portion of the torque and the speed reduction mechanism is smallest is referred to as an input-side minimum stiffness portion and a portion of the speed reduction mechanism and the output member where the young's modulus is smallest in a section where the torque is transmitted after being amplified by the speed reduction mechanism is referred to as an output-side minimum stiffness portion,

the Young's modulus of the output side minimum rigidity portion is smaller than that of the input side minimum rigidity portion,

the resolution of the output side rotation detector is lower than the resolution of the input side rotation detector.

Another driving device according to the present invention includes an input member to which torque is input, a speed reduction mechanism that reduces a speed of rotation of the input member, and an output member to which the rotation reduced by the speed reduction mechanism is transmitted, and the driving device further includes:

an input-side rotation detector for detecting rotation of the input member; and

an output-side rotation detector for detecting rotation of the output member,

the Young's modulus of the input side minimum rigidity portion is smaller than that of the output side minimum rigidity portion,

the resolution of the input side rotation detector is lower than the resolution of the output side rotation detector.

Effects of the invention

According to the present invention, the cost of components for detecting the torque of the drive device can be suppressed to a low level.

Drawings

Fig. 1 is a sectional view showing a driving device according to an embodiment of the present invention.

Fig. 2 is a diagram showing a control configuration of the drive device according to the embodiment.

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

Fig. 1 is a sectional view showing a driving device according to an embodiment of the present invention. The application of the driving device 1 of the present embodiment is not particularly limited, but the driving device can be used, for example, as a joint driving device of a cooperative robot that works in cooperation with a human. Hereinafter, the direction along the center axis O1 is referred to as the axial direction, the radial direction around the center axis O1 is referred to as the radial direction, and the rotational direction around the center axis O1 is referred to as the circumferential direction. The central axis O1 is the central axis of the shaft portion 16c of the output member 16 and the rotor shaft 13. The side of the central axis O1 where the output member 16 and the target member 202 are coupled in the axial direction (the left side in fig. 1) is referred to as the output side, and the opposite side (the right side in fig. 1) is referred to as the opposite output side or the input side.

The driving device 1 of the present embodiment includes: a frame 11 connected to a support member 201 outside the apparatus; an electric motor 12 having a part supported by the frame 11; a rotor shaft 13 to which torque is input from the electric motor 12; a brake mechanism 14, a part of which is supported by the frame 11 and which can apply a braking force to the rotor shaft 13; a speed reduction mechanism 15 that reduces the rotational speed of the rotor shaft 13; an output member 16 that outputs the rotational motion decelerated by the deceleration mechanism 15 to the outside of the apparatus; a circuit board (driver) 17 on which a drive circuit of the electric motor 12 is mounted; an input-side rotation detector 18 that detects rotation of the rotor shaft 13; and an output-side rotation detector 19 that detects rotation of the output member 16. The speed reduction mechanism 15, the electric motor 12, the brake mechanism 14, the rotation detection unit (the input-side rotation detector 18 and the output-side rotation detector 19), and the circuit board 17 are arranged in this order from the output side toward the opposite output side. The rotor shaft 13 and the oscillator 15a of the reduction mechanism 15 correspond to an example of an input member according to the present invention.

Frame 11 includes hollow cylindrical or annular members 11a to 11g coupled to each other, and is supported by support member 201 outside the apparatus. The

members

11f, 11g may be coupled to the member 11e via the members of the speed reducing mechanism 15. In the specific example of fig. 1, the support member 201 is fastened to the member 11f via a bolt, and the 1 st internal gear 15d is fastened between the support member 201 and the member 11 f. More specifically, the member 11a covers the inner structure on the opposite side of the output of the drive device 1 from the radial direction. A circuit board 17, an input-side rotation detector 18, and an output-side rotation detector 19 may be disposed in a portion covered by the member 11 a. The member 11b covers the internal structure of the drive device 1 from the axial direction on the opposite side to the output. The member 11b has a through hole penetrating in the axial direction, and the through hole of the member 11b and the through hole of the shaft portion 16c are arranged to communicate with each other. An outer ring of a bearing 21 is fitted to the member 11b, and the shaft portion 16c is rotatably supported by the member 11b via the bearing 21. The member 11b is coupled to the member 11a by bolts or the like. The member 11c is coupled to the member 11a by a bolt or the like, and covers the internal structure of the drive device 1 from the radial direction on the output side of the position where the member 11a is disposed. A brake mechanism 14 may be disposed in a portion covered by the member 11 c. The member 11d is coupled to the member 11c by a bolt or the like, and covers the internal structure of the drive device 1 from the radial direction on the output side of the position where the member 11c is disposed. An electric motor 12 may be disposed in a portion covered by the member 11 d. A part of the electric motor 12 (the stator 12a) is fixed to the frame 11 (e.g., the member 11 d). The member 11e is disposed on the output side of the member 11d, and is coupled to the member 11d by a bolt or the like. An outer ring of the bearing 23 is fitted to the member 11e, and the shaft portion of the oscillator 15a is rotatably supported by the member 11e via the bearing 23. The member 11e is also coupled to the 1 st ring gear 15d of the reduction mechanism 15 by bolts or the like. The member 11f is disposed on the output side of the reduction mechanism 15, and is coupled to the 1 st ring gear 15d of the reduction mechanism 15 by bolts or the like. The 1 st internal gear 15d has an extended portion extending from the output-side opposite side of the speed reduction mechanism 15 on which the tooth portions of the 1 st internal gear 15d are arranged toward the output side so as to cover the radially outer side of the 2 nd internal gear 15e, and the extended portion is coupled to the member 11 f. The member 11g is coupled to the member 11f and the 1 st internal gear 15d by bolts or the like, and covers the inner structure of the output side of the drive device 1 from the radial direction. The part 11f is fastened together between the part 11g and the 2 nd annulus gear 15 e. The outer ring of the bearing 22 is fitted to the member 11g, and the member 11g rotatably supports the output member 16 via the bearing 22. The member 11g has an extension portion extending to the output side of the bearing 22, and a seal made of dust or a lubricant is fitted to the extension portion. The structure of the frame 11 is not limited to the above specific example.

The output member 16 includes a member 16a, a member 16b, and a shaft portion 16c coupled to each other, and is rotatably supported by the frame 11 via bearings 21 and 22. The output member 16 has a hollow structure (hollow cylindrical shape). A part of the output member 16 is exposed to the output side, and the exposed part is coupled to the target member 202. More specifically, the shaft portion 16c penetrates the speed reduction mechanism 15 and extends to the side where the rotor shaft 13 is located. A rotating portion 19a of the output-side rotation detector 19 is fixed to the shaft portion 16c on the opposite side of the output from the speed reduction mechanism 15. The member 16a is disposed on the output side of the drive device 1, and one end of the shaft portion 16c is fitted thereto. The inner race of the bearing 22 is fitted to the member 16 a. The member 16a has an extended portion extending further to the output side than the bearing 22, and the extended portion is located on the inner peripheral side of the seal. A gasket, for example, is fitted to the extending portion to fill a gap on the inner peripheral side of the seal. The member 16b is disposed on the output-side opposite to the member 16a and on the output side of the speed reduction mechanism 15, a part of the output side of the member 16b is coupled to the member 16a by a bolt or the like, and a part of the output-side opposite to the member 16b is coupled to the 2 nd internal gear 15e of the speed reduction mechanism 15 by a bolt or the like. An outer ring of a bearing 24 is fitted to the member 16b, and the member 16b rotatably supports the oscillator 15a via the bearing 24. The member 16b is coupled to the target member 202 by bolts or the like. The component 16a is secured with the component 16b and the subject component 202 between them. The configuration of the output member 16 is not limited to the above specific example.

The electric motor 12 includes a stator 12a and a hollow cylindrical rotor 12 b. In the present embodiment, the rotor 12b is formed of a permanent magnet.

The rotor shaft 13 has a hollow structure, and is externally fitted to the shaft portion 16c of the output member 16 with a gap from the shaft portion 16c of the output member 16. The rotor shaft 13 is coupled to the rotor 12b of the electric motor 12. The electric motor 12 and the rotor shaft 13 are disposed on the opposite side of the output of the speed reduction mechanism 15. A rotating portion 18a of the input-side rotation detector 18 is fixed to the opposite side of the output of the rotor shaft 13.

The speed reduction mechanism 15 is a cylindrical flexible-meshing gear mechanism including a vibration generator 15a, a vibration generator bearing 15b, an external gear 15c that is flexible-deformed by rotation of the vibration generator 15a, and a 1 st internal gear 15d and a 2 nd internal gear 15e that mesh with the external gear 15 c. The oscillator 15a has a hollow structure and is fitted around the shaft portion 16c of the output member 16 with a gap from the shaft portion 16c of the output member 16. The oscillator 15a is coupled (e.g., spline-coupled) to the rotor shaft 13 and rotates integrally with the rotor shaft 13. The rotor shaft 13 and the oscillator 15a constitute an input member. The shaft of the oscillator 15a is rotatably supported by the frame 11 and the output member 16 via

bearings

23 and 24. In the oscillator 15a, the outer shape of the cross section perpendicular to the axial direction of the shaft portion is circular about the central axis O1, and the outer shape of the cross section perpendicular to the axial direction of the portion in contact with the oscillator bearing 15b is, for example, elliptical. The external gear 15c has flexibility. The 1 st internal gear 15d is coupled to the frame portion 11, and meshes with a range on the opposite side of the output in the axial direction of the external gear 15 c. The 2 nd internal gear 15e is coupled with the output member 16, and meshes with a range on the output side in the axial direction of the external gear 15 c.

In the speed reduction mechanism 15, the rotational motion is input to the oscillator 15a, and the rotational motion reduced is output to the 2 nd ring gear 15 e. In the speed reducing mechanism 15, the torque input to the oscillator 15a is amplified, the amplified torque is transmitted to the 2 nd internal gear 15e, and the reaction force of the amplified torque is transmitted to the 1 st internal gear 15 d. That is, the amplified torque is transmitted to the 1 st ring gear 15d and the 2 nd ring gear 15 e.

The 1 st internal gear 15d and the 2 nd internal gear 15e are made of a resin material. As the resin material, for example, simple resins such as synthetic resins; Fiber-Reinforced resins such as FRP (Fiber-Reinforced plastics) and CFRP (Carbon Fiber-Reinforced plastics). However, the resin material is not limited to this, and various resin materials such as paper phenol resin and cloth phenol resin may be used.

The input-side rotation detector 18 includes a rotating portion 18a that rotates integrally with the rotor shaft 13, and a detecting portion 18b that is disposed near the rotating portion 18a and detects the amount of rotation of the rotating portion 18 a. The output-side rotation detector 19 includes a rotating portion 19a that rotates integrally with the output member 16, and a detecting portion 19b that is disposed near the rotating portion 19a and detects the amount of rotation of the rotating portion 19 a. The input-side rotation detector 18 and the output-side rotation detector 19 are, for example, rotary encoders that output a displacement of rotation of the rotating portion as a digital signal, but a resolver (resolver) that outputs an analog signal may be used, or other rotation detectors may be used. The rotary encoder may have an optical detection unit or a magnetic detection unit. The input-side rotation detector 18 and the output-side rotation detector 19 may be different types of detectors.

The resolution of the input-side rotation detector 18 is higher than that of the output-side rotation detector 19. For example, the resolution of the input-side rotation detector 18 is 16 bits per rotation, while the resolution of the output-side rotation detector 19 is 8 bits per rotation.

In the input-side rotation detector 18 and the output-side rotation detector 19, two

detection units

18b and 19b are mounted on the circuit board 17, and two

rotation units

18a and 19a are disposed so as to face the two

detection units

18b and 19b from the output side of the circuit board 17. More specifically, the position where the rotating portion 19a is provided on the output member 16 and the position where the rotating portion 18a is provided on the rotor shaft 13 are located at substantially the same position in the axial direction, and similarly, the two detecting

portions

18b and 19b are also arranged at substantially the same position in the axial direction. That is, the rotating

portions

18a and 19a are disposed at positions overlapping each other when viewed in the radial direction, and the rotating portions 18a are disposed radially outward. Further, the detection unit 18b and the detection unit 19b are disposed at positions overlapping each other when viewed in the radial direction, and the detection unit 18b is disposed radially outward.

< description of action >

When the electric motor 12 is driven to rotate the rotor shaft 13 and the oscillator 15a, the motion of the oscillator 15a is transmitted to the external gear 15 c. At this time, the shape of the external gear 15c is limited to a shape conforming to the outer peripheral surface of the oscillator 15a, and the external gear is flexed into an elliptical shape having a major axis portion and a minor axis portion as viewed in the axial direction. Further, the long shaft portion of the external gear 15c meshes with the fixed 1 st internal gear 15 d. Therefore, the external gear 15c does not rotate at the same rotational speed as the oscillator 15a, but the oscillator 15a relatively rotates inside the external gear 15 c. Then, the external gear 15c is deformed in a flexural manner so that the long axis position and the short axis position thereof move in the circumferential direction in accordance with the relative rotation. The deformation period is proportional to the rotation period of the oscillator 15 a. When the external gear 15c is deformed, the long-axis position thereof moves, and the meshing position of the external gear 15c and the 1 st internal gear 15d changes in the rotational direction. Here, it is assumed that the number of teeth of the external gear 15c is 100 and the number of teeth of the 1 st internal gear 15d is 102. In this way, the external gear 15c rotates (rotates) by sequentially shifting the meshing teeth of the external gear 15c and the 1 st internal gear 15d every rotation of the meshing position. If the number of teeth is set as described above, the rotational motion of the oscillator 15a is reduced at a reduction ratio of 100:2 and then transmitted to the external gear 15 c. On the other hand, since the external gear 15c also meshes with the 2 nd internal gear 15e, the meshing position of the external gear 15c and the 2 nd internal gear 15e also changes in the rotational direction by the rotation of the oscillator 15 a. Here, if the number of teeth of the 2 nd internal gear 15e is equal to the number of teeth of the external gear 15c, the external gear 15c and the 2 nd internal gear 15e do not rotate relative to each other, and the rotational motion of the external gear 15c is transmitted to the 2 nd internal gear 15e at a reduction ratio of 1: 1. Thereby, the rotational motion of the oscillator 15a is reduced at a reduction ratio of 100:2, transmitted to the 2 nd internal gear 15e, and output from the 2 nd internal gear 15e to the target member 202 via the output member 16.

In the transmission of the rotational motion, the rotational position of the rotor shaft 13 is detected by the input-side rotation detector 18, and the rotational position of the output member 16 is detected by the output-side rotation detector 19.

< Torque Transmission and detection >

Here, a case where torque and rotational motion are transmitted from the drive device 1 to the target member 202 coupled to the output member 16 will be described. At this time, the torque and the rotational motion output from the electric motor 12 are transmitted from the rotor shaft 13 to the speed reduction mechanism 15, the torque is amplified by the speed reduction mechanism 15, and the rotational motion is reduced. Then, the amplified torque and the decelerated rotational motion are transmitted from the deceleration mechanism 15 to the target member 202 via the output member 16.

The torque transmission portion before amplification is a portion of the rotor shaft 13 from the torque input portion (the connection portion of the rotor 12 b) to the connection portion with the oscillator 15a, and a portion of the oscillator 15a from the connection portion with the rotor shaft 13 to the contact portion with the oscillator bearing 15 b. The oscillator 15a and the rotor shaft 13 are made of a metal such as steel, for example. In these sections, if the section having the smallest young's modulus is referred to as the input-side minimum rigidity section, these sections correspond to the input-side minimum rigidity section, and the young's modulus corresponds to the young's modulus of the metal. Further, since the portion of the rotor shaft 13 on the opposite side of the torque input portion from the speed reduction mechanism is not a portion through which the torque before amplification is transmitted (passed), the material (young's modulus) thereof is not particularly limited, but in the present embodiment, it is made of metal as in the other portions of the rotor shaft 13.

The portion (section) of the frame 11 from the connection portion with the support member 201 to the connection portion with the 1 st internal gear 15d, the external gear 15c, the 2 nd internal gear 15e, and the section of the output member 16 from the connection portion with the 2 nd internal gear 15e to the connection portion with the target member 202 are configured by a portion that transmits the amplified torque to the support member 201 and receives the torque, and a portion through which the amplified torque transmitted to the target member 202 passes. In the specific example of fig. 1, the torque amplified by the speed reduction mechanism 15 is transmitted in a section from the member 11f of the frame portion 11 to the

members

16b, 16a of the output member 16 through the 1 st internal gear 15d, the external gear 15c, and the 2 nd internal gear 15 e. The 1 st and 2 nd

internal gears

15d and 15e are made of a resin material as described above, and the other portions are made of a metal such as a steel material. Among these portions, when the portion having the smallest young's modulus is referred to as the output-side minimum stiffness portion, the output-side minimum stiffness portions are the 1 st ring gear 15d and the 2 nd ring gear 15e, and the young's modulus thereof corresponds to the young's modulus of the resin material.

When torque is transmitted, since the member is strained by the torque, the rotational position of the output member 16 is shifted from the output-side reference position. In an ideal configuration without strain, the output-side reference position indicates the rotational position of the output member 16 corresponding to the rotational positions of the rotor shaft 13 and the vibration generating body 15 a. The strain amount can be measured from the deviation of the output member 16 from the output-side reference position. Since the torque and the amount of strain have a constant relationship, the torque can be detected from the amount of strain.

Since only a small torque is applied to the rotor shaft 13, strain in the rotational direction is small, and the strain amount is reduced by an amount corresponding to the reduction ratio via the reduction mechanism 15 and affects the output side. Therefore, even if the output side is an ideal configuration in which no strain is generated, it is necessary to detect the amount of strain in the rotational direction of the rotor shaft 13 from the deviation of the output member 16 from the output side reference position, and the resolution of the rotation detection of the output member 16 needs to be very high.

Since a large torque is applied to the output-side members (the output member 16, the 1 st ring gear 15d, and the 2 nd ring gear 15e), the strain in the rotational direction thereof is large, and the magnitude of the strain directly affects as a deviation of the rotational position of the output member 16. Therefore, it is easy to detect the amount of strain in the rotational direction of the output side from the deviation of the output member 16 from the output side reference position.

However, the output side reference position is determined according to the rotational position of the rotor shaft 13, but the rotational amount of the rotor shaft 13 is reduced at the reduction ratio of the reduction mechanism 15 and transmitted to the output side. Therefore, the output-side reference position can be determined more finely with respect to the resolution of the rotation detection of the rotor shaft 13. For example, the rotational position of the rotor shaft 13 can be detected every 1 degree, and the output-side reference position can be determined every 0.02 degree (1 degree/50) when the reduction ratio is 1/50. If the output-side reference position can be determined more finely, the displacement of the output member 16 from the output-side reference position can be measured with high accuracy. In this case, the resolution of the rotation detection on the output side needs to be equal to the notch of the reference position on the output side. If the resolution of the rotation detection on the output side is lowered, the measurement accuracy of the deviation (strain amount) of the output member 16 from the output-side reference position is lowered in accordance with the lowered resolution. When the strain amount is small relative to the torque, if the measurement resolution of the strain amount is low, the error of the torque detection becomes large.

Therefore, in the present embodiment, the young's modulus of the output-side minimum rigidity portion is set to be lower than the young's modulus of the input-side minimum rigidity portion. Accordingly, the strain in the rotational direction of the output member 16 with respect to the torque becomes large, and even if the resolution of the measured strain amount becomes low, the detection error of the torque can be suppressed to be low. Further, since the allowable resolution of the strain amount to be measured can be reduced, the assembly cost of the output-side rotation detector 19 is suppressed by setting the resolution of the output-side rotation detector 19 lower than the resolution of the input-side rotation detector 18.

< calculation Structure of Torque >

As shown in fig. 2, the drive device 1 of the present embodiment further includes a calculation unit 31 that calculates the torque output to the target member 202. The arithmetic unit 31 is a microcomputer or the like, and may be mounted on the circuit board 17 or may be provided separately from the circuit board 17.

The calculation unit 31 includes, for example, an I/O33 to which the detection values are input from the input-side rotation detector 18 and the output-side rotation detector 19, a storage unit 34 in which a data table 34a indicating the relationship between the deviation of the rotation position of the output member 16 from the output-side reference position and the torque is stored, and a torque calculation unit 32 that obtains the torque output from the output member 16 to the target member 202. The torque calculation unit 32 may calculate a deviation of the rotation position of the output member 16 from the output reference position from the respective detection values of the input-side rotation detector 18 and the output-side rotation detector 19, and may determine the torque by comparing the calculation result with the data table 34 a. The table values in the data table 34a are obtained by measuring the offset by adding the various torques through experiments.

The torque obtained by the calculation unit 31 is output to, for example, a higher-level control device, and if the torque exceeds the limit torque, the device may be stopped or used as data for detecting that something (e.g., a person) accidentally comes into contact with the target member 202.

As described above, according to the drive device 1 of the present embodiment, the young's modulus of the output side minimum rigidity portions (the 1 st ring gear 15d and the 2 nd ring gear 15e) is lower than the young's modulus of the input side minimum rigidity portions (the rotor shaft 13 and the oscillator 15 a). Also, the resolution of the output side rotation detector 19 is lower than that of the input side rotation detector 18. Therefore, as described above, the cost of the output-side rotation detector 19 can be reduced, and the torque with a small error can be detected from the detection values of the input-side rotation detector 18 and the output-side rotation detector 19.

Further, according to the drive device 1 of the present embodiment, the output side minimum rigidity portion is made of a resin material, and the input side minimum rigidity portion is made of a metal material. According to this structure, it is possible to suppress a decrease in the kinetic performance of the drive device 1, and to obtain appropriate rigidity and appropriate flexibility suitable for reducing an error in torque detection. Further, since it has appropriate rigidity and appropriate flexibility, it is suitably applied to, for example, a device for moving a joint of a cooperative robot that works in cooperation with a human.

The driving device 1 according to the present embodiment further includes a calculation unit 31 that calculates the torque to be output to the target member 202 based on the detection values of the input-side rotation detector 18 and the output-side rotation detector 19. Since the torque output to the target member 202 can be converted into the torque acting on each portion between the output member 16 and the input member (the rotor shaft 13 and the vibrating body 15a), the calculation unit 31 can be regarded as a portion for calculating the torque acting on each portion. According to the calculation unit 31, the torque can be obtained without using an expensive sensor for directly detecting the torque, and the calculation unit can be used for various controls based on the torque.

Further, according to the drive device 1 of the present embodiment, the internal gears (15d, 15e) of the reduction mechanism 15 are used as the output side minimum rigidity portions. As long as the internal gear is provided, the radial thickness of the gear can be increased without changing the pitch circle diameter. Therefore, the thickness of the gear can be increased without changing the meshing structure and size of the gear, and the strength deficiency due to the reduction in rigidity can be easily compensated for.

Further, according to the drive device 1 of the present embodiment, the speed reduction mechanism 15 is a cylindrical flexible mesh gear mechanism, and the 1 st internal gear 15d and the 2 nd internal gear 15e are employed as the output side minimum rigidity portions. With this configuration, it is possible to easily realize a configuration in which an appropriate offset amount occurs in the rotational position of the output member 16 in accordance with the torque while suppressing a decrease in the strength of the device due to the provision of the output-side minimum rigidity portion.

Further, according to the drive device 1 of the present embodiment, the output member 16 has the shaft portion 16c, and the shaft portion 16c penetrates the speed reduction mechanism 15 and extends to the input side of the torque of the input member (the rotor shaft 13 and the oscillator 15 a). The output-side rotation detector 19 is disposed closer to the input-side rotation detector 18 than the speed reduction mechanism 15. Therefore, the input-side rotation detector 18 and the output-side rotation detector 19 can be brought close to each other and can be integrated at a position where both signals are extracted to the outside. Alternatively, the signal lines for transmitting the respective signals to the arithmetic section using two signals may be combined. By combining these components, the electric components can be assembled in a concentrated manner, and therefore, the complexity of the assembly process of the drive device 1 can be reduced.

(modification example)

In the above embodiment, the young's modulus of the output side minimum rigidity portion is lower than the young's modulus of the input side minimum rigidity portion, and the resolution of the output side rotation detector 19 is lower than the resolution of the input side rotation detector 18. The driving device of the modified example is configured such that the young's modulus of the input-side minimum rigidity portion is lower than the young's modulus of the output-side minimum rigidity portion and the resolution of the input-side rotation detector 18 is lower than the resolution of the output-side rotation detector 19. The rest is the same as the drive device 1 of the above embodiment. In the drive device of the modified example, the 1 st ring gear 15d and the 2 nd ring gear 15e of the speed reduction mechanism 15 are made of metal such as steel, for example, and the section of the input member (the rotor shaft 13 and the oscillator 15a) to which torque is transmitted may include a resin structure portion, for example.

According to the drive device of the modified example, for example, in an ideal configuration without strain, when the rotational position of the rotor shaft 13 corresponding to the rotational position of the output member 16 is set as the input-side reference position and the torque is obtained from the deviation of the rotational position of the rotor shaft 13 from the input-side reference position, a large strain corresponding to the torque is obtained on the input side as compared with the output side. Therefore, the resolution of the input-side rotation detector 18 can be reduced, cost reduction can be achieved, and the torque can be obtained with high accuracy.

The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments. For example, the speed reduction mechanism is not limited to the cylindrical type flexible engagement gear mechanism, and various mechanisms such as a cup type or top hat type flexible engagement gear mechanism, a planetary gear mechanism, and an eccentric oscillating type speed reduction mechanism may be used. In the above-described embodiment, an example is shown in which a resin is used for a portion having a low young's modulus and a metal is used for a portion having a high young's modulus out of the input-side minimum rigidity portion and the output-side minimum rigidity portion, but the material is not particularly limited as long as the magnitude relationship of the young's modulus can be maintained, and for example, two types of metals having different young's moduli may be applied to a portion having a low young's modulus and a portion having a high young's modulus. In the embodiment, the example in which the 1 st ring gear 15d and the 2 nd ring gear 15e are applied as the output side minimum rigidity portion is shown, but the output side minimum rigidity portion may be provided only in a section where torque amplified by the speed reduction mechanism is transmitted, and may be, for example, one of the 1 st ring gear 15d and the 2 nd ring gear 15e, or may be an output member, a frame portion, or a part thereof. In the embodiment, the entire rotor shaft 13 and the oscillator 15a are the input-side minimum stiffness portion, but the input-side minimum stiffness portion may be provided between the torque input portion and the speed reduction mechanism in the input member, and for example, a portion having a low young's modulus may be set to be different between the rotor shaft 13 and the oscillator 15a as the input-side minimum stiffness portion. The brake mechanism 14, the circuit board 17, or both of them provided in the driving device 1 according to the embodiment may be omitted, and a mechanism for generating rotational power such as the electric motor 12 may be omitted, and instead, rotational power may be input to the input member from the outside via the motion transmission mechanism. In addition, the detailed configuration shown in the embodiment can be appropriately modified within a scope not departing from the gist of the invention.

Industrial applicability

The present invention can be used for a drive device.

Description of the symbols

1-drive device, 11-frame, 12-electric motor, 13-rotor shaft (input member), 14-brake mechanism, 15-reduction mechanism, 15 a-vibrator (input member), 15 c-external gear, 15 d-first internal gear, 15 e-second internal gear, 16-output member, 16 c-shaft, 17-circuit substrate, 18-input side rotation detector, 18 a-rotating part, 18 b-detecting part, 19-output side rotation detector, 19 a-rotating part, 19 b-detecting part, 31-arithmetic part, 32-torque calculating part, 34 a-data table, 201-support member, 202-object member.

Claims

1. A drive device including an input member to which torque is input, a speed reduction mechanism that reduces a speed of rotation of the input member, and an output member to which the rotation reduced by the speed reduction mechanism is transmitted, the drive device further comprising:

an input-side rotation detector for detecting rotation of the input member; and

an output-side rotation detector for detecting rotation of the output member,

in the case where a portion of the input member where the young's modulus between the input portion of the torque and the speed reducing mechanism is minimum is referred to as an input-side minimum rigidity portion and a portion of the speed reducing mechanism and the output member where the young's modulus is minimum in a section where the torque amplified by the speed reducing mechanism is transmitted is referred to as an output-side minimum rigidity portion,

2. The drive device according to claim 1,

the input-side least rigid portion is made of metal,

the output side minimum rigidity portion is made of resin.

3. The drive device according to claim 1 or 2,

the control device further includes a calculation unit that calculates a torque acting on a portion between the input member and the output member based on a detection value of the input-side rotation detector and a detection value of the output-side rotation detector.

4. The drive device according to any one of claims 1 to 3,

the reduction mechanism has an internal gear and an external gear meshing with the internal gear,

the output side minimum rigidity portion is the internal gear.

5. The drive device according to any one of claims 1 to 4,

the reduction gear mechanism is a flexible meshing type gear mechanism having an external gear, a vibration generator for flexibly deforming the external gear, and a 1 st internal gear and a 2 nd internal gear meshing with the external gear,

the output-side minimum rigidity portions are the 1 st internal gear and the 2 nd internal gear.

6. The drive device according to any one of claims 1 to 5,

the output member penetrates the speed reduction mechanism and extends to an input side of torque of the input member,

the output-side rotation detector is provided on the input side of the speed reduction mechanism.

7. A drive device including an input member to which torque is input, a speed reduction mechanism that reduces a speed of rotation of the input member, and an output member to which the rotation reduced by the speed reduction mechanism is transmitted, the drive device further comprising:

an input-side rotation detector for detecting rotation of the input member; and

an output-side rotation detector for detecting rotation of the output member,