Harmonic speed reduction transmission device

Abstract

A harmonic speed reduction transmission device includes a harmonic reducer connected to a motor, wherein a sensing part and a transmission part are respectively formed at both ends of the motor rotor, and the harmonic reducer has a rigid wheel, a flexible wheel meshing in the rigid wheel, and a waveform generating group that drives the flexible wheel to rotate; wherein the transmission part is used as an elliptical disk in the waveform generating group, so that the transmission part sequentially drives a flexible bearing and a flexible wheel in the waveform generating group to rotate, thereby simplifying the structural configuration and outputting a speed with a predetermined reduction ratio.

Description

[Technical Field]

[0001] This invention relates to the structure of harmonic reducers and motors, and particularly to a harmonic reduction transmission device. [Previous Technology]

[0002] Harmonic reducers generate deceleration by means of the elastic deformation of metal. They are commonly used in the transmission structure of industrial robots and humanoid robots. They have advantages such as small size, light weight, large load capacity, high motion accuracy and large single-stage transmission ratio.

[0003] Traditional harmonic reducers typically house a rigid wheel, a flexible wheel, and a waveform generation assembly within a single housing. Wherein:

[0004] The rigid wheel is a hollow annular wheel body, fixed inside the housing and having multiple internal teeth distributed in a ring, which are used to provide a guiding function when the flexible wheel rotates.

[0005] The flexible wheel is a hollow annular wheel body, and has a thin-walled part that can deform and a thick-walled part that can maintain rigidity; the thin-walled part has a smooth inner wall surface and a plurality of external teeth that are distributed in a ring and can mesh with the internal teeth of the rigid wheel, the number of teeth of the external teeth is usually less than the number of internal teeth (generally two fewer teeth); the thick-walled part is used as a power output end of the harmonic reducer.

[0006] The waveform generating group is a columnar assembly, comprising an elliptical disk and a flexible bearing tightly coupled to the periphery of the elliptical disk; the elliptical disk can be used as a power input end of the harmonic reducer, and the flexible bearing is a type of thin-walled ball bearing, the outer wall of which can be tightly coupled to the inner wall surface of the flexible wheel.

[0007] Accordingly, when the harmonic reducer drives the elliptical disk to rotate via rotational torque, the elliptical disk can sequentially force the flexible bearing and the thin-walled portion of the flexible wheel to form a consistent ellipse, thereby causing the flexible wheel to rotate in the opposite direction around the rigid wheel. During this period, since the number of teeth on the outer teeth of the flexible wheel is slightly less than the number of teeth on the inner teeth of the rigid wheel, and the thin-walled portion of the flexible wheel has been formed into an ellipse, the flexible wheel can actually only mesh with the inner teeth of the rigid wheel at the two opposite ends in the direction of the major axis of the ellipse, and rotate slowly on the inner teeth of the rigid wheel with the same circumference. This means that for every rotation of the elliptical disk (360 degrees), the flexible wheel can only rotate a small arc in the opposite direction (360 degrees) (depending on the number of teeth reduced on the outer teeth of the flexible wheel), so that the rotational speed of the flexible wheel relative to the elliptical disk is much slower, thereby achieving the effect of deceleration, that is, the thick-walled portion of the flexible wheel can output a rotational torque with a predetermined reduction ratio.

[0008] Furthermore, the harmonic reducer typically needs to be combined with a motor to form a harmonic reduction transmission device, wherein the motor provides rotational torque to the harmonic reducer to provide reduced rotational torque externally. The motor excites a rotor to rotate via a stator, and the rotor must rely on at least one connecting component to drive the thick-walled portion of the flexible wheel; however, this results in a more complicated assembly process and makes it difficult to miniaturize its structural volume.

[0009] It is known that existing patents JP-5659446B2 and CN109895122B have representatively disclosed the transmission connection technology of the above-mentioned harmonic reducer and motor; however, these patents still require a similar or identical connection component to connect the rotational torque of the motor rotor to the harmonic reducer, so it is still difficult to overcome the problem of the complicated assembly process and the problem of the difficulty in miniaturizing the structure under the torque output requirement of a specific reduction ratio.

[0010] The aforementioned technical defects have had a significant impact on the research and development goals of miniaturization and refinement of industrial robots and humanoid robots, and therefore urgently need to be improved. [Summary of the Invention]

[0011] In view of the technical defects of the prior art, the inventors have focused on the integration between the rotor of the motor and the elliptical disk of the waveform generation group to simplify the assembly process and reduce the internal space of the harmonic reducer, thereby achieving the purpose of miniaturization of the structure.

[0012] Therefore, a preferred embodiment of the present invention provides a harmonic speed reduction transmission device, which includes a harmonic reducer and a motor arranged coaxially within a housing; the harmonic reducer includes a rigid wheel fixed within the housing, a flexible wheel meshing within the rigid wheel, and a waveform generating assembly that drives the flexible wheel to rotate; the waveform generating assembly includes an elliptical disk and a flexible bearing coupled between the elliptical disk and the flexible wheel; the motor includes a stator fixed within the housing and a rotor pivotally disposed within the stator; wherein the rotor forms a sensing part and a transmission part relative to the sensing part, the surface of the sensing part is formed with at least one polarity pair by permanent magnets, and the sensing part is located within the stator to receive electromagnetic induction from the stator, wherein most notably, the elliptical disk is formed by the transmission part.

[0013] As can be seen from the above technical features, the present invention specifically integrates the elliptical disk of the waveform generation group onto the rotor of the motor, so that there is no need to add the conventional connecting components between the rotor and the elliptical disk, thus achieving the effect of reducing the number of structures and simplifying the assembly process.

[0014] In a further embodiment, since the rigid wheel has a plurality of internal teeth arranged in a ring, the flexible wheel has a thin-walled portion that can deform and a thick-walled portion that can maintain rigidity. The thin-walled portion has a smooth inner wall surface and a plurality of external teeth arranged in a ring around the periphery of the thin-walled portion. The flexible wheel engages with the flexible bearing by means of the inner wall surface and engages with a portion of the internal teeth of the rigid wheel by means of the external teeth.

[0015] To this end, the present invention has specially designed the housing so that the housing is formed by pivotally connecting a housing base and a housing cover in a half-fractal shape. The housing base provides fixation for the rigid wheel, and the housing cover provides fixation for the thick-walled portion of the flexible wheel, so that the housing cover becomes a power output end of the harmonic deceleration transmission device.

[0016] More specifically, a first receiving chamber is formed within the housing, and a second receiving chamber communicating with the first receiving chamber is formed within the housing cover. The sensing portions of the stator and the rotor are located within the first receiving chamber, the transmission portion of the rotor extends into the second receiving chamber, and the harmonic reducer is located between the first and second receiving chambers. Furthermore, the rotor also has a central pivot hole, and the housing has a central seat portion that can extend into the central pivot hole. The rotor is pivotally mounted between the central seat portion and the stator via the central pivot hole. In addition, the central seat portion is formed within the housing, and the central seat portion has a hole. A central post extends within the housing cover and can be pivotally connected to the hole.

[0017] Compared with the prior art, the present invention makes a technical contribution in reducing the internal space of the device and achieving the purpose of miniaturizing the structure.

[0018] Furthermore, at least one of the housing and the rigid wheel is formed with an annular guide groove, and the housing cover is formed with a protruding ring that can receive the guide groove. In this way, for the housing cover used as a power output end, stability will be improved when rotating relative to the housing.

[0019] Furthermore, as long as the aforementioned housing and cover can maintain their pivotal connection and have an internal accommodating chamber, the remaining structural features can be interchanged or slightly modified, all of which fall within the scope of application conceived by this invention. Moreover, the embodiments and technical effects disclosed above will be explained in more detail in the following drawings and embodiments.

Implementation Method

[0020] First, please refer to Figures 1 to 4 together. The main components of the harmonic speed reduction transmission device of the present invention include: a housing 20, a harmonic reducer 30 and a motor 40 arranged coaxially within the housing 20. As can be seen from Figures 1 and 2, the harmonic reducer 30 includes a rigid wheel 31 fixed coaxially within the housing 20, a flexible wheel 32 meshing with the rigid wheel 31, and a waveform generating group 33 that drives the flexible wheel 32 to rotate. The waveform generating group 33 includes an elliptical disk 331 and a flexible bearing 332 connected between the elliptical disk 331 and the flexible wheel 32. The motor 40 can be one of a brushless DC motor and a permanent magnet AC synchronous motor, and includes a stator 41 fixed within the housing 20 and a rotor 42 pivotally placed within the stator 41.

[0021] As shown in Figures 1 and 3, the housing 20 in Figure 2 is an annular body and is formed by a bifurcated annular housing seat 21 and an annular housing cover 22 pivotally connected to each other. The housing seat 21 and the housing cover 22 are respectively formed with multiple inner surfaces in the shape of annular trapezoids, thereby constructing a first receiving chamber 210 in the housing seat 21 and a second receiving chamber 220 in the housing cover 22 that can communicate with the first receiving chamber 210, for accommodating the harmonic reducer 30 and the motor 40 shown in Figure 2.

[0022] Furthermore, the housing 21 can be regarded as the fixed end of the transmission device, used to lock onto a device requiring an end. The center of the housing 21 can form a central seat portion 211 protruding toward the first accommodating chamber 210. A hole 212 is provided in the central seat portion 211, and the center of the housing cover 22 forms a central post 221 that can extend to the seat hole 212, for mounting a first bearing 51 between the seat hole 212 and the central post 221, so that the housing cover 22 can be pivotally connected to the seat hole 212 by means of the central post 221 and the first bearing 51; In addition, an annular guide groove 213 can be formed at one end of the housing 21 adjacent to the housing cover 22, and the housing cover 22 forms a protruding ring 222 that can be guided by the guide groove 213, so that the housing cover 22 can rotate freely and stably relative to the housing 21, serving as the power output end of the transmission device.

[0023] As described above, the central seat portion 211, seat hole 212, and guide groove 213 of the housing 21 can also be formed inside the housing cover 22. In this way, the central pillar 221 and the protruding ring 222 of the housing cover 22 are formed inside the housing 21. In other words, as long as the housing 21 and the housing cover 22 can be pivotally connected to each other and have interconnected accommodating chambers inside, they are all within the scope of the technical implementation of the present invention.

[0024] As shown in Figures 1 and 2, the configuration of the rigid wheel 31 and the flexible wheel 32 is disclosed. The rigid wheel 31 has an annular convex disc 311, which allows it to be tightly fixed to the inner surface of the housing 21 adjacent to the cover 22 by means of the outer surface of the convex disc 311, so that the rigid wheel 31 remains stationary during deceleration transmission. In addition, the rigid wheel 31 also has a plurality of annularly distributed internal teeth 312 for guiding the flexible wheel 32. Furthermore, the guide groove 213 may also be formed on the rigid wheel 31 for guiding the convex ring 222 of the cover 22.

[0025] Furthermore, the flexible wheel 32 is formed with a thin-walled portion 321 capable of deformation and a thick-walled portion 322 capable of maintaining rigidity. The thin-walled portion 321 has a smooth inner wall surface 321a and a plurality of external teeth 321b arranged in a ring around the periphery of the thin-walled portion 321. The flexible wheel 32 is coupled to the flexible bearing 332 by means of the inner wall surface 321a and engages with a portion of the inner teeth 312 of the rigid wheel 31 by means of the external teeth 321b, so that the rigid wheel 31 can guide the rotation of the flexible wheel 32. In addition, the flexible wheel 32 can be fixed to the housing cover 22 by means of the locking screw through the thick-walled portion 322, so that the flexible wheel 32 can synchronously drive the housing cover 22 to rotate, thereby using the housing cover as a power output end of this transmission device.

[0026] As shown in FIG4, the configuration details between the rotor 42 and the flexure 32 of the motor 40 shown in FIG2 are disclosed. The rotor 42 has a sensing part 421 and a transmission part 422 formed along the axial direction, and the sensing part 421 is located in the stator 41 to receive the electromagnetic induction of the stator 41, and the elliptical disk 331 of the waveform generating group 33 is formed by the transmission part 422. In other words, the sensing part 421 is formed by combining a cylindrical magnet base 421a with multiple permanent magnets 421b, and the multiple permanent magnets 421b can respectively form at least one polarity pair with an externally manifested N pole and S pole. In Figure 4, it is shown that the surface of the sensing part 421 has multiple polarity pairs, but in practice only one polarity pair is needed to receive the electromagnetic induction after the coil in the stator 41 is energized and magnetized, and drive the rotor 42 to generate rotational torque. Furthermore, the cross-section of the transmission part 422 is elliptical, which serves as the elliptical disk 331 of the waveform generation group 33. In addition, Figure 4 also shows that the rotor 42 has a central pivot hole 424. As shown in Figure 2, the rotor 42 can be pivotally mounted between the central seat 211 and the stator 41 by means of at least one second bearing 52 disposed in the central pivot hole 424. Furthermore, Figure 4 further reveals the structural features of the thin-walled portion 321, the thick-walled portion 322, the inner wall surface 321a, and the outer teeth 321b of the flexible wheel 32 shown in Figure 2, as well as the configuration feature of the flexible bearing 332 being able to be arranged between the inner wall surface 321a of the flexible wheel 32 and the transmission portion 422 (i.e., the elliptical disk 331) of the rotor 42.

[0027] Accordingly, when the stator 41 of the motor 40 excites the rotor 42 to rotate, the transmission part 422 (i.e., the elliptical disk 331) located on the rotor 42 rotates accordingly, and sequentially forces the flexible bearing 332 and the thin-walled portion 321 of the flexible wheel 32 to form a consistent ellipse, thereby driving the flexible wheel 32 to rotate in the opposite direction around the rigid wheel 31; at this time, since the number of teeth of the outer teeth 321b of the flexible wheel 32 is less than the number of teeth of the inner teeth 312 of the rigid wheel 31 (usually two fewer teeth), and the thin-walled portion 321 of the flexible wheel 32 has been formed into an ellipse, the flexible wheel 32 can actually only have the outer teeth 321b at the two opposite ends in the direction of the major axis of the ellipse mesh with a portion of the inner teeth 312 of the rigid wheel 31, and slowly rotate on the inner teeth 312 of the rigid wheel 31. In other words, for every rotation (360 degrees) of the rotor 42 with the elliptical disk 331, the flexible wheel 32 can rotate in the opposite direction by a small arc (depending on the number of teeth reduced on the outer teeth of the flexible wheel). That is, the speed at which the cover 22, which is fixed to the flexible wheel 32, can output a predetermined speed reduction ratio is relatively slower than the speed generated by the rotor 42, so as to achieve the predetermined harmonic deceleration effect.

[0028] As shown in Figure 2, with the above-described configuration, the sensing portion 421 of the stator 41 and the rotor 42 can be located within the first accommodating chamber 210, the transmission portion 422 (or elliptical disk 331) of the rotor 42 can extend into the second accommodating chamber 220, and the harmonic reducer 30 can be located between the first accommodating chamber 210 and the second accommodating chamber 220. Since the transmission portion 422 of the rotor 42 can be used as the elliptical disk 331 of the waveform generating group 33, no additional connecting component is needed between the rotor 42 and the elliptical disk 331. Therefore, it has the effect of reducing the number of structures and simplifying the assembly process. This invention can indeed make a technical contribution to reducing the internal space of this transmission device and thus achieving the goal of miniaturizing the structure. [Simplified Explanation of the Diagram]

[0029] Figure 1 is an exploded perspective view of the harmonic speed reduction transmission device of the present invention. Figure 2 is a cross-sectional view of Figure 1. Figure 3 is an explanatory cross-sectional view of the housing shown in Figure 2, illustrating that the housing is formed by the pivotal connection of a bi-fidelity housing base and a housing cover. Figure 4 is an explanatory assembly view of the motor rotor and flexure shown in Figure 2, illustrating the configuration of the rotor's transmission part connected to the flexure via a flexible bearing.

Claims

1. A harmonic speed reduction transmission device, configured coaxially within a housing, comprising: A harmonic reducer includes a rigid wheel fixed within a housing, a flexible wheel meshing within the rigid wheel, and a waveform generating assembly that drives the flexible wheel to rotate. The waveform generating assembly includes an elliptical disk and a flexible bearing coupled between the elliptical disk and the flexible wheel. A motor includes a stator fixed within the housing and a rotor pivotally mounted within the stator. The rotor has a sensing portion and a transmission portion relative to the sensing portion. The sensing portion is located within the stator and receives electromagnetic induction from the stator. The elliptical disk is formed by the transmission portion. The flexible wheel has a thick-walled portion that maintains rigidity. The housing is formed by a bi-fidelity housing seat and a housing cover pivotally connected to each other. The housing seat provides fixation for the rigid wheel, and the housing cover provides fixation for the thick-walled portion of the flexible wheel, making the housing cover a power output end of the harmonic reducer. The rotor also has a central pivot hole, and the housing has a central seat portion that can extend into the central pivot hole. The rotor is pivotally mounted between the central seat portion and the stator by means of the central pivot hole, and the central seat portion has a hole. A central column extends from the housing cover and can be pivotally connected to the hole.

2. The harmonic deceleration transmission device as claimed in claim 1, wherein the rigid wheel has a plurality of internal teeth arranged in an annular pattern, and the flexible wheel also has a thin-walled portion capable of deformation, the thin-walled portion having a smooth inner wall surface and a plurality of external teeth arranged in an annular pattern around the periphery of the thin-walled portion, the flexible wheel engaging the flexible bearing by means of the inner wall surface and engaging a portion of the internal teeth of the rigid wheel by means of the external teeth.

3. The harmonic speed reducer as claimed in claim 1, wherein a first receiving chamber is formed within the housing, a second receiving chamber communicating with the first receiving chamber is formed within the housing cover, the sensing portions of the stator and the rotor are located within the first receiving chamber, the transmission portion of the rotor extends into the second receiving chamber, and the harmonic speed reducer is located between the first receiving chamber and the second receiving chamber.

4. The harmonic speed reduction drive as claimed in claim 1, wherein the induction surface of the rotor is formed with at least one polarity pair by permanent magnets.

5. The harmonic reduction gear as claimed in claim 1, wherein at least one of the housing and the rigid wheel is formed with an annular guide groove, and the housing cover is formed with a convex ring capable of receiving the guide groove.

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