Drive device

Abstract

The present invention provides a drive device that can detect the torque output from a drive device with high accuracy and can suppress the cost of components for detecting the torque to a low level. The drive device (1) comprises an input component (13, 15a) for inputting torque, a speed reduction mechanism (15), an output component (16) for transmitting the rotation after speed reduction, an input-side rotation detector (18) for detecting the rotation of the input component, and an output-side rotation detector (19) for detecting the rotation of the output component. Moreover, the Young's modulus of the parts (15d, 15e) with the smallest Young's modulus in the speed reduction mechanism (15) and the output component (16) is smaller than the Young's modulus of the parts with the smallest Young's modulus in the input components (13, 15a), and the resolution of the output-side rotation detector (19) is lower than the resolution of the input-side rotation detector (18).

Description

Technical Field

[0001] The invention relates to a driving device. Background Art

[0002] Patent document 1 discloses a robot device having a joint that is rotationally driven via a rotary motor and a reducer. The robot device of Patent document 1 includes: an input-side encoder that generates a pulse signal each time the rotary motor makes a small rotation; a rectangular wave generating unit that generates a pulse signal according to the rotation angle of the joint; an output-side encoder that generates a pulse signal each time the joint makes a small rotation at the output side of the reducer; and a control unit that calculates the torsion angle of the joint based on these pulse signals.

[0003] Previous technical literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2014-65097 Summary of the invention

[0006] Technical issues to be solved by the invention

[0007] In a drive device that amplifies input torque via a speed reducer and outputs it, strain is generated between an input member and an output member according to the torque. If a strain sensor or a high-resolution encoder is used to detect the strain, the component cost of the device will increase.

[0008] An object of the present invention is to provide a drive device capable of suppressing the cost of components for detecting the torque of the drive device.

[0009] Means for solving technical problems

[0010] The drive device according to the present invention comprises an input member for inputting torque, a speed reduction mechanism for reducing the speed of rotation of the input member, and an output member for transmitting the rotation reduced by the speed reduction mechanism, and the drive device further comprises:

[0011] an input-side rotation detector for detecting the rotation of the input component; and

[0012] an output side rotation detector for detecting the rotation of the output component,

[0013] When the portion of the input member where the Young's modulus is the smallest between the torque input portion and the reduction mechanism is referred to as the input-side minimum rigidity portion, and the portion of the reduction mechanism and the output member where the Young's modulus is the smallest in the torque transmission section amplified by the reduction mechanism is referred to as the output-side minimum rigidity portion,

[0014] The Young's modulus of the minimum rigidity portion on the output side is smaller than the Young's modulus of the minimum rigidity portion on the input side,

[0015] The resolution of the output-side rotation detector is lower than the resolution of the input-side rotation detector.

[0016] Another drive device according to the present invention comprises an input member for inputting torque, a speed reduction mechanism for reducing the speed of rotation of the input member, and an output member for transmitting the rotation reduced by the speed reduction mechanism, and the drive device further comprises:

[0017] an input-side rotation detector for detecting the rotation of the input component; and

[0018] an output side rotation detector for detecting the rotation of the output component,

[0019] When the portion of the input member where the Young's modulus is the smallest between the torque input portion and the reduction mechanism is referred to as the input-side minimum rigidity portion, and the portion of the reduction mechanism and the output member where the Young's modulus is the smallest in the torque transmission section amplified by the reduction mechanism is referred to as the output-side minimum rigidity portion,

[0020] The Young's modulus of the minimum rigidity portion on the input side is smaller than the Young's modulus of the minimum rigidity portion on the output side,

[0021] The resolution of the input-side rotation detector is lower than the resolution of the output-side rotation detector.

[0022] Effects of the Invention

[0023] According to the present invention, the cost of components for detecting the torque of a drive device can be suppressed to be low. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a cross-sectional view showing a driving device according to an embodiment of the present invention.

[0025] Figure 2 It is a diagram showing a control structure of a drive device according to an embodiment. DETAILED DESCRIPTION

[0026] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0027] Figure 1: is a cross-sectional view of a drive device according to an embodiment of the present invention. The use of the drive device 1 according to the present embodiment is not particularly limited, but, for example, it can be used as a joint drive device for a collaborative robot that works in collaboration with a human. Hereinafter, the direction along the central axis O1 is referred to as the axial direction, the radial direction about the central axis O1 is referred to as the radial direction, and the rotation direction about the central 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 component 16 and the rotor shaft 13. Furthermore, the output component 16 on the axial direction of the central axis O1 is connected to the side of the object component 202 ( Figure 1 The left side of the output side is called the output side, and the opposite side ( Figure 1 The right side of the output is called the opposite side of the output or the input side.

[0028] The drive device 1 of this embodiment includes: a frame 11 connected to a support member 201 outside the device; an electric motor 12 partially supported by the frame 11; a rotor shaft 13 to which torque is input from the electric motor 12; a brake mechanism 14 partially supported by the frame 11 and capable of applying a braking force to the rotor shaft 13; a speed reduction mechanism 15 that reduces the speed of the rotation of the rotor shaft 13; an output member 16 that outputs the rotation of the speed reduction mechanism 15 to the outside of the device; 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 the rotation of the rotor shaft 13; and an output-side rotation detector 19 that detects the rotation of the output member 16. The speed reduction mechanism 15, the electric motor 12, the brake mechanism 14, the rotation detector (the input-side rotation detector 18 and the output-side rotation detector 19), and the circuit board 17 are arranged in order from the output side to the opposite output side. The rotor shaft 13 and the vibrator 15a of the speed reduction mechanism 15 correspond to an example of the input member involved in the present invention.

[0029] The frame 11 includes hollow cylindrical or annular components 11a to 11g connected to each other, and supported by a support component 201 outside the device. Components 11f and 11g can be connected to component 11e via components of the speed reduction mechanism 15. Figure 1In the specific example, the support member 201 is fastened to the member 11f via bolts, and the first internal gear 15d is fastened to the support member 201 and the member 11f between them. More specifically, the member 11a covers the internal structure of the drive device 1 on the opposite side of the output from the radial direction. The circuit substrate 17, the input side rotation detector 18 and the output side rotation detector 19 can be arranged in the portion covered by the member 11a. The member 11b covers the internal structure of the drive device 1 on the opposite side of the output from the axial direction. The member 11b has a through hole penetrating in the axial direction, and is arranged so that the through hole of the member 11b is connected to the through hole of the shaft portion 16c. The outer ring of the bearing 21 is fitted on the member 11b, and the member 11b supports the shaft portion 16c rotatably via the bearing 21. The member 11b is connected to the member 11a by bolts or the like. The member 11c is connected to the member 11a by bolts or the like, and covers the internal structure of the drive device 1 from the radial direction at a position closer to the output side than the arrangement position of the member 11a. The brake mechanism 14 may be arranged in the portion covered by the component 11c. The component 11d is connected to the component 11c by bolts or the like, and covers the internal structure of the drive device 1 from the radial direction at a position closer to the output side than the position where the component 11c is arranged. The electric motor 12 may be arranged in the portion covered by the component 11d. A portion (stator 12a) of the electric motor 12 is fixed to the frame 11 (for example, the component 11d). The component 11e is arranged on the output side of the component 11d, and is connected to the component 11d by bolts or the like. The outer ring of the bearing 23 is fitted on the component 11e, and the component 11e supports the shaft of the vibrator 15a via the bearing 23 so that it can rotate. Moreover, the component 11e is also connected to the first internal gear 15d of the reduction mechanism 15 by bolts or the like. The component 11f is arranged on the output side of the reduction mechanism 15, and is connected to the first internal gear 15d of the reduction mechanism 15 by bolts or the like. The first internal gear 15d has an extension portion extending toward the output side from the output opposite side of the speed reduction mechanism 15 on which the tooth portion of the first internal gear 15d is arranged so as to cover the radial outer side of the second internal gear 15e, and the extension portion is connected to the component 11f. The component 11g is connected to the component 11f and the first internal gear 15d by bolts or the like, and covers the internal structure of the output side of the drive device 1 from the radial direction. The component 11f is fastened between the component 11g and the second internal gear 15e. The outer ring of the bearing 22 is fitted on the component 11g, and the component 11g supports the output component 16 rotatably via the bearing 22. The component 11g has an extension portion extending toward the output side further than the bearing 22, and a seal of dust or lubricating material is fitted in the extension portion. In addition, the structure of the frame portion 11 is not limited to the above-mentioned specific example.

[0030] The output component 16 includes a component 16a, a component 16b and a shaft 16c connected to each other, and is rotatably supported by the frame 11 via bearings 21 and 22. The output component 16 has a hollow structure (hollow cylindrical). A portion of the output component 16 is exposed on the output side, and the exposed portion is connected to the object component 202. More specifically, the shaft 16c penetrates the reduction mechanism 15 and extends to the side where the rotor shaft 13 is located. The rotating portion 19a of the output side rotation detector 19 is fixed to the output opposite side of the shaft 16c than the reduction mechanism 15. The component 16a is arranged on the output side of the drive device 1, and one end of the shaft 16c is embedded. The inner ring of the bearing 22 is embedded in the component 16a. The component 16a has an extension portion extending further to the output side than the bearing 22, and the extension portion is located on the inner peripheral side of the seal. For example, a gasket is embedded in the extension portion to fill the gap on the inner peripheral side of the seal. The component 16b is arranged on the output side of the reduction mechanism 15 and opposite to the output side of the component 16a. A part of the output side of the component 16b is connected to the component 16a by bolts or the like, and a part of the output side of the component 16b is connected to the second internal gear 15e of the reduction mechanism 15 by bolts or the like. The outer ring of the bearing 24 is fitted on the component 16b, and the component 16b supports the vibrator 15a rotatably via the bearing 24. The component 16b is connected to the object component 202 by bolts or the like. The component 16a is fastened between the component 16b and the object component 202. In addition, the structure of the output component 16 is not limited to the above-mentioned specific example.

[0031] The electric motor 12 includes a stator 12a and a hollow cylindrical rotor 12b. In the present embodiment, the rotor 12b is formed of a permanent magnet.

[0032] 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 therebetween. The rotor shaft 13 is connected to the rotor 12b of the electric motor 12. The electric motor 12 and the rotor shaft 13 are arranged on the output opposite side of the speed reduction mechanism 15. On the output opposite side of the rotor shaft 13, the rotating portion 18a of the input side rotation detector 18 is fixed.

[0033] The speed reduction mechanism 15 is a cylindrical flexural meshing gear mechanism, which includes an oscillator 15a, an oscillator bearing 15b, an external gear 15c that is flexibly deformed by the rotation of the oscillator 15a, and a first internal gear 15d and a second internal gear 15e that mesh with the external gear 15c. The oscillator 15a has a hollow structure and is externally fitted to the shaft portion 16c of the output member 16 with a gap therebetween. The oscillator 15a is connected (for example, splined) to the rotor shaft 13 so as to rotate integrally with the rotor shaft 13. The rotor shaft 13 and the oscillator 15a constitute an input member. The shaft portion of the oscillator 15a is rotatably supported by the frame portion 11 and the output member 16 via bearings 23 and 24. In the vibrator 15a, the outer shape of the cross section of the shaft portion perpendicular to the axial direction is a circle centered on the central axis O1, and the outer shape of the cross section of the portion in contact with the vibrator bearing 15b perpendicular to the axial direction is, for example, an ellipse. The external gear 15c has flexibility. The first internal gear 15d is connected to the frame 11 and meshes with the range on the opposite side of the output in the axial direction of the external gear 15c. The second internal gear 15e is connected to the output member 16 and meshes with the range on the output side in the axial direction of the external gear 15c.

[0034] In the speed reduction mechanism 15, the rotational motion is input to the oscillating body 15a, and the decelerated rotational motion is output to the second internal gear 15e. In the speed reduction mechanism 15, the torque input to the oscillating body 15a is amplified, the amplified torque is transmitted to the second internal gear 15e, and the reaction force of the amplified torque is transmitted to the first internal gear 15d. That is, the amplified torque is transmitted to the first internal gear 15d and the second internal gear 15e.

[0035] The first internal gear 15d and the second internal gear 15e are made of a resin material. As the resin material, for example, a simple resin such as a synthetic resin or a fiber-reinforced resin such as FRP (Fiber-Reinforced Plastic) or CFRP (Carbon Fiber Reinforced Plastic) can be used. However, the present invention is not limited to these, and various resin materials such as paper phenolic resin or cloth phenolic resin can also be used as the resin material.

[0036] The input side rotation detector 18 has a rotating part 18a that rotates integrally with the rotor shaft 13, and a detection part 18b that is arranged near the rotating part 18a and detects the rotation amount of the rotating part 18a. The output side rotation detector 19 has a rotating part 19a that rotates integrally with the output member 16, and a detection part 19b that is arranged near the rotating part 19a and detects the rotation amount of the rotating part 19a. The input side rotation detector 18 and the output side rotation detector 19 are, for example, rotary encoders that output the rotation displacement of the rotating part as digital signals, but a resolver that outputs an analog signal may be used, or other rotation detectors may be used. The rotary encoder may have an optical detection part or a magnetic detection part. The input side rotation detector 18 and the output side rotation detector 19 may use detectors of different types.

[0037] 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, whereas the resolution of the output side rotation detector 19 is 8 bits per rotation.

[0038] In the input side rotation detector 18 and the output side rotation detector 19, two detection parts 18b and 19b are mounted on the circuit substrate 17, and the two rotating parts 18a and 19a are arranged to face the two detection parts 18b and 19b from the output side of the circuit substrate 17. More specifically, the setting position of the rotating part 19a on the output member 16 and the setting position of the rotating part 18a on the rotor shaft 13 are located at approximately the same position in the axial direction, and similarly, the two detection parts 18b and 19b are also arranged at approximately the same position in the axial direction. That is, when viewed from the radial direction, the rotating part 18a and the rotating part 19a are arranged at positions overlapping each other, and the rotating part 18a is arranged on the radially outer side. And, when viewed from the radial direction, the detection part 18b and the detection part 19b are arranged at positions overlapping each other, and the detection part 18b is arranged on the radially outer side.

[0039] <Action Description>

[0040] When the electric motor 12 is driven to rotate the rotor shaft 13 and the vibrator 15a, the movement of the vibrator 15a is transmitted to the external gear 15c. At this time, the shape of the external gear 15c is limited to conform to the shape of the outer peripheral surface of the vibrator 15a, and it is bent into an elliptical shape having a major axis portion and a minor axis portion when viewed from the axial direction. Moreover, the major axis portion of the external gear 15c meshes with the fixed first internal gear 15d. Therefore, the external gear 15c does not rotate at the same speed as the vibrator 15a, but the vibrator 15a rotates relatively inside the external gear 15c. Moreover, along with this relative rotation, the external gear 15c is bent and deformed in a manner that its major axis position and minor axis position move in the circumferential direction. The deformation period is proportional to the rotation period of the vibrator 15a. When the external gear 15c is bent and deformed, its major axis position moves, so that the meshing position of the external gear 15c and the first internal gear 15d changes in the rotation direction. Here, it is assumed that the number of teeth of the external gear 15c is 100 and the number of teeth of the first internal gear 15d is 102. In this way, the meshing teeth of the external gear 15c and the first internal gear 15d are sequentially offset for each rotation of the meshing position, and the external gear 15c rotates (rotates). If the number of teeth is set as above, the rotational motion of the oscillator 15a is transmitted to the external gear 15c after being reduced by a reduction ratio of 100:2. On the other hand, the external gear 15c is also meshed with the second internal gear 15e, so the meshing position of the external gear 15c and the second internal gear 15e also changes in the rotation direction by the rotation of the oscillator 15a. Here, if the number of teeth of the second internal gear 15e is set to the same number as the number of teeth of the external gear 15c, the external gear 15c and the second internal gear 15e will not rotate relative to each other, and the rotational motion of the external gear 15c is transmitted to the second internal gear 15e at a reduction ratio of 1:1. Thus, the rotational motion of the vibrator 15 a is reduced in speed at a reduction ratio of 100:2, transmitted to the second internal gear 15 e , and output from the second internal gear 15 e to the counterpart member 202 via the output member 16 .

[0041] During the transmission of the above-mentioned 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 .

[0042] <Torque transmission and detection>

[0043] Here, the case where the torque and the rotational motion are transmitted from the drive device 1 to the target component 202 connected to the output member 16 is 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 reduction mechanism 15, and the torque is amplified by the reduction mechanism 15, while the rotational motion is decelerated. Then, the amplified torque and the decelerated rotational motion are transmitted from the reduction mechanism 15 to the target component 202 via the output member 16.

[0044] The torque transmission part before amplification is the section from the torque input part (the connection part of the rotor 12b) to the connection part with the vibrator 15a in the rotor shaft 13 and the section from the connection part with the rotor shaft 13 to the contact part with the vibrator bearing 15b in the vibrator 15a. The above sections in the vibrator 15a and the rotor shaft 13 are made of metal such as steel. Among these sections, if the part with the smallest Young's modulus is called the input side minimum rigidity part, then these sections are equivalent to the input side minimum rigidity part, and their Young's modulus is equivalent to the Young's modulus of the metal. In addition, the part of the rotor shaft 13 that is closer to the side opposite to the speed reduction mechanism than the torque input part is not the part where the torque is transmitted (passed) before amplification, so its material (Young's modulus) is not particularly limited, but in this embodiment, it is made of metal like other parts of the rotor shaft 13.

[0045] The portion (section) where the amplified torque is transmitted is composed of a portion that transmits the amplified torque to the supporting member 201 and receives the torque, and a portion where the amplified torque is transmitted to the target member 202, and is a section in the frame 11 from the connection portion with the supporting member 201 to the connection portion with the first internal gear 15d, the first internal gear 15d, the external gear 15c, the second internal gear 15e, and the section in the output member 16 from the connection portion with the second internal gear 15e to the connection portion with the target member 202. Figure 1 In the specific example, the torque amplified by the speed reduction mechanism 15 is transmitted in the section from the component 11f of the frame 11 through the first internal gear 15d, the external gear 15c and the second internal gear 15e to the components 16b and 16a of the output component 16. Among them, the first internal gear 15d and the second internal gear 15e are made of resin material as described above, and the other parts are made of metal such as steel. Among these parts, if the part with the smallest Young's modulus is called the output side minimum rigidity part, then the output side minimum rigidity part is the first internal gear 15d and the second internal gear 15e, and its Young's modulus is equivalent to the Young's modulus of the resin material.

[0046] When torque is transmitted, the components will generate strain due to the torque, so the rotational position of the output component 16 will deviate from the output side reference position. In an ideal structure without strain, the output side reference position represents the rotational position of the output component 16 corresponding to the rotational position of the rotor shaft 13 and the vibrator 15a. The amount of strain can be measured based on the deviation of the output component 16 from the output side reference position. In addition, there is a constant relationship between the torque and the strain, so the torque can be detected based on the strain.

[0047] Since only a small torque is applied to the rotor shaft 13, the strain in the rotation direction is small, and the strain amount is reduced by an amount corresponding to the reduction ratio through the speed reduction mechanism 15 and affects the output side. Therefore, even if the output side is an ideal structure where no strain is generated, in order to detect the strain amount in the rotation direction of the rotor shaft 13 based on the deviation of the output member 16 from the output side reference position, the resolution of the rotation detection of the output member 16 needs to be very high.

[0048] Since a large torque is applied to the components on the output side (the output component 16, the first internal gear 15d, and the second internal gear 15e), the strain in the rotational direction is large, and the magnitude of the strain directly affects the deviation of the rotational position of the output component 16. Therefore, it is relatively easy to detect the amount of strain in the rotational direction of the output side based on the deviation of the output component 16 from the output side reference position.

[0049] However, the output side reference position is determined based on the rotation position of the rotor shaft 13, but the rotation amount of the rotor shaft 13 is transmitted to the output side after being reduced by the reduction ratio of the reduction mechanism 15. Therefore, the output side reference position can be determined more finely relative to the resolution of the rotation detection of the rotor shaft 13. For example, the rotation position of the rotor shaft 13 can be detected every 1 degree. If the reduction ratio is 1 / 50, the output side reference position can be determined every 0.02 degree (=1 degree / 50). If the output side reference position can be determined more finely, the deviation of the output member 16 from the output side reference position can be measured with high accuracy. At this time, the resolution of the rotation detection on the output side needs to be equal to the groove of the output side reference position. If the resolution of the rotation detection on the output side is reduced, the measurement accuracy of the deviation (strain amount) of the output member 16 from the output side reference position will be reduced accordingly. In the case where the strain amount is small relative to the torque, if the measurement resolution of the strain amount becomes low, the error of the torque detection will become larger.

[0050] Therefore, in the present embodiment, the Young's modulus of the minimum rigidity portion on the output side is set to be lower than the Young's modulus of the minimum rigidity portion on the input side. As a result, the strain in the rotation direction of the output member 16 becomes larger relative to the torque, and even if the resolution of the measured strain amount becomes lower, the detection error of the torque can be suppressed to a low level. In addition, since the allowable resolution of the measured strain amount can be reduced, the component 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.

[0051] <Torque calculation structure>

[0052] Figure 2 It is a diagram showing a control structure of a drive device according to an embodiment.

[0053] like Figure 2 As shown, the drive device 1 of this embodiment further includes a calculation unit 31 for calculating the torque output to the target component 202. The calculation 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.

[0054] The calculation unit 31 includes, for example, an I / O 33 that inputs each detection value from the input side rotation detector 18 and the output side rotation detector 19, a storage unit 34 that stores 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, and a torque calculation unit 32 that calculates the torque output from the output member 16 to the target member 202. The torque calculation unit 32 can calculate the deviation of the rotation position of the output member 16 from the output reference position based on each detection value of the input side rotation detector 18 and the output side rotation detector 19, and compare the calculation result with the data table 34a to calculate the torque. The table values ​​in the data table 34a are obtained by measuring the deviation by adding various torques through experiments.

[0055] The torque obtained by the calculation unit 31 is output to a higher-level control device, for example. If it exceeds the limit torque, the device can be stopped, or it can be used as data for detecting that something (for example, a person) accidentally contacts the target component 202 .

[0056] As described above, according to the drive device 1 of this embodiment, the Young's modulus of the minimum rigidity portion on the output side (the first internal gear 15d and the second internal gear 15e) is lower than the Young's modulus of the minimum rigidity portion on the input side (the rotor shaft 13 and the vibrator 15a). In addition, the resolution of the output side rotation detector 19 is lower than the resolution 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 based on the detection values ​​of the input side rotation detector 18 and the output side rotation detector 19.

[0057] Moreover, according to the drive device 1 of this embodiment, the minimum rigidity portion on the output side is made of a resin material, and the minimum rigidity portion on the input side is made of a metal material. According to this structure, it is possible to suppress the reduction in the motion performance of the drive device 1, and it is possible to obtain appropriate rigidity and appropriate flexibility suitable for reducing the error of torque detection. In addition, since it has appropriate rigidity and appropriate flexibility, it can be well applied to a device for moving the joints of a cooperative robot that works in cooperation with a human, for example.

[0058] Furthermore, according to the drive device 1 of the present embodiment, there is provided a calculation unit 31 for calculating the torque output to the target component 202 based on the detection values ​​of the input side rotation detector 18 and the output side rotation detector 19. In addition, the torque output to the target component 202 can be converted into the torque acting on each part between the output component 16 and the input component (rotor shaft 13 and vibrator 15a), so the calculation unit 31 can be regarded as a part for calculating the torque acting on the above-mentioned each part. According to such a calculation unit 31, the torque can be obtained even without using an expensive sensor that directly detects the torque, and can be used for various torque-based controls.

[0059] Furthermore, according to the drive device 1 of this embodiment, the internal gear (15d, 15e) of the speed reduction mechanism 15 is used as the minimum rigidity portion on the output side. As long as it is an internal gear, 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, so that the lack of strength caused by the reduction of rigidity can be easily compensated.

[0060] Furthermore, according to the drive device 1 of this embodiment, the speed reduction mechanism 15 is a cylindrical flexure meshing gear mechanism, and the first internal gear 15d and the second internal gear 15e are used as the output side minimum rigidity portion. According to this structure, it is possible to suppress the reduction in the strength of the device caused by providing the output side minimum rigidity portion, and it is possible to easily realize a structure in which an appropriate offset amount occurs in the rotational position of the output member 16 according to the torque.

[0061] Moreover, according to the drive device 1 of the present embodiment, the output component 16 has a shaft portion 16c, and the shaft portion 16c passes through the reduction mechanism 15 and extends to the input side of the torque of the input component (rotor shaft 13 and vibrator 15a). Moreover, the output side rotation detector 19 is arranged at a position closer to the input side rotation detector 18 than the 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 converged at a position where the two signals are led out to the outside. Alternatively, the signal lines that transmit each signal to the operation unit that uses the two signals can be converged. Through these convergences, the assembly of electrical components can be concentrated, thereby reducing the complexity of the assembly process of the drive device 1.

[0062] (Variation Example)

[0063] In the above-mentioned embodiment, a structure is adopted in which the Young's modulus of the minimum rigidity portion on the output side is lower than the Young's modulus of the minimum rigidity portion on the input side and the resolution of the output side rotation detector 19 is lower than the resolution of the input side rotation detector 18. The drive device of the modified example is configured so that the Young's modulus of the minimum rigidity portion on the input side is lower than the Young's modulus of the minimum rigidity portion on the output side 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-mentioned embodiment. In the drive device of the modified example, for example, the first internal gear 15d and the second internal gear 15e of the speed reduction mechanism 15 are made of metal such as steel, and on the other hand, the torque transmission section in the input member (rotor shaft 13 and vibrator 15a) may include, for example, a resin structure.

[0064] According to the drive device of the modified example, for example, in an ideal structure without strain, when the rotation position of the rotor shaft 13 corresponding to the rotation position of the output member 16 is set as the input side reference position and the torque is obtained based on the deviation of the rotation position of the rotor shaft 13 from the input side reference position, a larger strain corresponding to the torque is obtained on the input side than on the output side. Therefore, the resolution of the input side rotation detector 18 can be reduced to achieve cost reduction, and the torque can be obtained with high accuracy.

[0065] The above is a description of the embodiment of the present invention. However, the present invention is not limited to the above embodiment. For example, the speed reduction mechanism is not limited to the cylindrical flexure meshing gear mechanism, and various mechanisms such as the so-called cup-type or top-hat flexure meshing gear mechanism, planetary gear mechanism, eccentric swing type speed reduction mechanism, etc. can also be used. In addition, in the above embodiment, an example is shown in which the part with low Young's modulus in the input side minimum rigidity part and the output side minimum rigidity part is made of resin and the part with high Young's modulus is made of metal, but as long as the magnitude relationship of the Young's modulus can be maintained, the material is not particularly limited. For example, two metals with different Young's moduli can be applied to the part with low Young's modulus and the part with high Young's modulus, respectively. In addition, in the embodiment, an example is shown in which the first internal gear 15d and the second internal gear 15e are applied as the minimum rigidity part on the output side, but the minimum rigidity part on the output side can be set in the torque transmission section after being amplified by the speed reduction mechanism, for example, it can be one of the first internal gear 15d and the second internal gear 15e, or it can be an output component, a frame or a part thereof. In the embodiment, the rotor shaft 13 and the vibrator 15a as a whole are set as the minimum rigidity part on the input side, but the minimum rigidity part on the input side only needs to be set between the torque input part and the speed reduction mechanism in the input component. For example, the Young's modulus of the rotor shaft 13 and the vibrator 15a can be set to be different and the part with a low Young's modulus can be used as the minimum rigidity part on the input side. The brake mechanism 14, the circuit substrate 17 or both of them provided in the drive device 1 of the embodiment can be omitted, and the mechanism for generating rotational power such as the electric motor 12 can also be omitted, and the rotational power can be input to the input component from the outside via a motion transmission mechanism instead. In addition, the detailed structure shown in the embodiment can be appropriately changed without departing from the scope of the purpose of the invention.

[0066] Industrial Applicability

[0067] The present invention can be utilized in a driving device.

[0068] Explanation of symbols

[0069] 1-driving device, 11-frame, 12-electric motor, 13-rotor shaft (input component), 14-braking mechanism, 15-reduction mechanism, 15a-oscillator (input component), 15c-external gear, 15d-first internal gear, 15e-second internal gear, 16-output component, 16c-shaft, 17-circuit board, 18-input side rotation detector, 18a-rotating part, 18b-detecting part, 19-output side rotation detector, 19a-rotating part, 19b-detecting part, 31-calculating part, 32-torque calculating part, 34a-data table, 201-supporting part, 202-object part.

Claims

1. A drive device comprising an input member for inputting torque, a speed reduction mechanism for reducing the speed of rotation of the input member, and an output member for transmitting the rotation reduced by the speed reduction mechanism, wherein the drive device further comprises: an input-side rotation detector for detecting the rotation of the input component; and an output side rotation detector for detecting the rotation of the output component, When the portion of the input member where the Young's modulus is the smallest between the torque input portion and the reduction mechanism is referred to as the input-side minimum rigidity portion, and the portion of the reduction mechanism and the output member where the Young's modulus is the smallest in the torque transmission section amplified by the reduction mechanism is referred to as the output-side minimum rigidity portion, The Young's modulus of the minimum rigidity portion on the output side is smaller than the Young's modulus of the minimum rigidity portion on the input side, The resolution of the output-side rotation detector is lower than the resolution of the input-side rotation detector.

2. The driving device according to claim 1, characterized in that: The input side least rigid part is made of metal, The output side minimum rigidity portion is made of resin.

3. The driving device according to claim 1 or 2, characterized in that: A calculation unit is further provided for calculating 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 driving device according to claim 1 or 2, characterized in that: The speed reduction mechanism comprises an internal gear and an external gear meshing with the internal gear. The minimum rigidity portion on the output side is the internal gear.

5. The driving device according to claim 1 or 2, characterized in that: The speed reduction mechanism is a flexural meshing type gear mechanism including an external gear, a vibrator that flexibly deforms the external gear, and a first internal gear and a second internal gear that mesh with the external gear. The output-side minimum rigidity portion is the first internal gear and the second internal gear.

6. The driving device according to claim 1 or 2, characterized in that: The output member penetrates the speed reduction mechanism and extends to the torque input side of the input member. The output-side rotation detector is provided at a position closer to the input side than the speed reduction mechanism.

7. A drive device comprising an input member for inputting torque, a speed reduction mechanism for reducing the speed of rotation of the input member, and an output member for transmitting the rotation reduced by the speed reduction mechanism, wherein the drive device further comprises: an input-side rotation detector for detecting the rotation of the input component; and an output side rotation detector for detecting the rotation of the output component, When the portion of the input member where the Young's modulus is the smallest between the torque input portion and the reduction mechanism is referred to as the input-side minimum rigidity portion, and the portion of the reduction mechanism and the output member where the Young's modulus is the smallest in the torque transmission section amplified by the reduction mechanism is referred to as the output-side minimum rigidity portion, The Young's modulus of the minimum rigidity portion on the input side is smaller than the Young's modulus of the minimum rigidity portion on the output side, The resolution of the input-side rotation detector is lower than the resolution of the output-side rotation detector.

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