Speed reducer including planetary gear and harmonic drive

Abstract

A speed reducer according to the present invention comprises: a harmonic drive including a wave generator; a plurality of spur gears connected to a cam plate of the wave generator; and an input gear that extends in an axial direction, passes through a central portion of the cam plate, and is geared with the plurality of spur gears. The wave generator comprises: a circular central portion and three protrusions formed on the outer circumferential surface of the central portion; and a ball bearing arranged to surround the cam plate and elastically deformed by the three protrusions. The speed reducer according to the present invention includes both a planetary gear structure and a three-point driving harmonic drive, and thus prevents a dead idle state and significantly increases a tooth engagement rate, and makes it possible to greatly improve reducer performance factors, such as rated torque, peak torque, and the like, while maximizing the reduction ratio.

Description

Reducers including planetary gears and harmonic drives

[0001] The present invention relates to a reducer including a planetary gear structure and a three-point driving harmonic drive.

[0002] A reducer is coupled to the motor, the power source, and serves to reduce the output rotational speed, thereby achieving high rotational torque and reducing speed. Reducers can be selected based on factors such as reduction ratio, output torque, backlash, and rotational accuracy. With the advancement of electric vehicles and autonomous vehicles, demand for reducers, which are essential components for these vehicles, is steadily increasing. Active research and development is also underway to tailor reducers to the specific specifications and performance of these vehicles.

[0003] Reducers are used not only in vehicles but also in robots. Robots include domestic robots used for tasks such as caring for patients or children, or assisting with cooking and cleaning, as well as industrial robots such as vertical / horizontal multi-joint robots and mobile robots with robot arms used in industrial manufacturing. Reducers are a critical component in the joint drive mechanisms of these robots.

[0004] Reducers used in various industrial fields come in various types, such as planetary gear reducers, cylindrical gear reducers, cycloid reducers, harmonic reducers, and hybrid reducers, depending on their shape, configuration, and operating principles.

[0005] Planetary gear reducers boast a very high power transmission ratio per unit volume, enabling greater power transmission than gear reducers of the same size. Furthermore, planetary gear reducers can have concentric drive and driven shafts, and offer a wide range of reduction ratios and high power transmission efficiency. Consequently, they are used in a wide range of industries, including not only the aforementioned vehicles and robots, but also aircraft and machine tools.

[0006] Meanwhile, a harmonic reducer is a reducer that uses the bending of a rigid body to mesh with planetary gears, and is very advantageous in miniaturizing high-rigidity, high-output devices due to its large basic reduction ratio and low backlash, so it is widely used in ultra-precision positioning mechanisms, multi-joint robots, etc. Conventional harmonic reducers are two-point reducers and include a wave generator such as that disclosed in Korean Patent No. 10-1557677 (Title of the invention: Noncircular bearing, wave generator, and wave gear device). The wave generator includes a plug inside, and the plug has an oval shape and is connected to the input shaft of the drive system to transmit rotational motion, and at the same time, the plug shape of the wave generator elastically deforms a thin cup-shaped flex spline, causing the flex spline to generate a decelerating rotational motion in the opposite direction. The harmonic reducer receives rotational force from the input shaft of the drive system, and the wave generator rotates. The flex spline changes shape to be the same as the plug, that is, in an elliptical shape, so that the positions of the teeth that mesh with the circular splines in the long axis of the ellipse sequentially move. When the wave generator makes a complete rotation, the flex spline rotates in the opposite direction by the difference in the number of teeth, and deceleration is achieved due to this rotation in the opposite direction. Since the conventional harmonic reducer operates with a symmetrical tooth meshing structure in the long axis of the ellipse, a problem called dedoidal often occurs in which the teeth mesh state is momentarily disengaged when the assembly is forced or a ratcheting shock with a large external force occurs.

[0007] With the rapid development of electric vehicles, robots, etc., there is a growing demand for performance improvement in reducers, and in particular, research and development is needed on ways to maximize reduction ratios while resolving the problems of conventional reducers mentioned above.

[0008] The present invention has been conceived in consideration of the above-described technical requirements, and the object of the present invention is to provide a reducer capable of preventing a dead-end state, significantly increasing its biting ratio, and significantly improving reducer performance items such as rated torque and peak torque, while maximizing the reduction ratio.

[0009] In order to achieve the above object, a reducer according to the present invention comprises: a harmonic drive including a wave generator; a plurality of spur gears connected to a cam plate of the wave generator; and an input gear extending in the axial direction and penetrating the center of the cam plate and gear-engaged with the plurality of spur gears; wherein the wave generator comprises: a central portion having a circular shape; three protrusions formed on an outer circumferential surface of the central portion; and a ball bearing arranged to surround the cam plate and elastically deformed by the three protrusions.

[0010] And, it may include a cover flange including a hole through which the input gear passes; an output side flange arranged to face the cover flange; and a fixed flange arranged between the cover flange and the output side flange.

[0011] Additionally, the output side flange includes a receiving space in which the tip of the input gear is received, and a ball bearing may be arranged between the inner surface of the receiving space and the tip of the input gear.

[0012] And, the cam plate may include a cam plate extension extending in the axial direction, and a ball bearing may be provided between the cam plate extension and the output side flange.

[0013] Additionally, the output side flange may include a side wall protruding in the axial direction, and the ball bearing may be provided between the cam plate extension and the side wall.

[0014] And, the cover flange includes a side wall protruding in the axial direction, and a ball bearing can be arranged between the side wall of the cover flange and the input gear.

[0015] Additionally, the gears of the input gear can be arranged to mesh with the gears of the plurality of spur gears.

[0016] Meanwhile, a device according to the present invention for achieving the above object includes: an output-side flange; a harmonic drive disposed spaced apart from the output-side flange and including a wave generator; a shaft extending axially and penetrating the output-side flange and the cam plate of the wave generator; a bevel gear fastened to one end of the shaft; and an input-side cover flange having an accommodation space formed to accommodate the other end of the shaft.

[0017] And, the input side cover flange includes a side wall protruding in the axial direction, and the receiving space can be formed by the side wall.

[0018] In addition, it may further include a tapered roller bearing disposed between the inner side of the receiving space and the tip of the shaft.

[0019] And, it may further include a sealing ring (C-ring) supporting the tapered roller bearing.

[0020] Additionally, the output side flange may include a through hole through which the shaft passes, and a bearing may be provided between the inner wall of the through hole and the shaft.

[0021] And, the distance between the cam plate of the wave generator and the output side flange may be closer than the distance between the cam plate and the input side cover flange.

[0022] Meanwhile, a device according to the present invention for achieving the above object includes: an input-side cover flange; a harmonic drive disposed spaced apart from the input-side cover flange and including a wave generator; a shaft extending in the axial direction and penetrating the input-side cover flange and the cam plate of the wave generator; a bevel gear fastened to one end of the shaft; and an output-side flange having an accommodation space formed to accommodate the other end of the shaft.

[0023] And, the output side flange includes a side wall protruding in the axial direction, and the receiving space can be formed by the side wall.

[0024] In addition, it may further include a tapered roller bearing disposed between the inner side of the receiving space and the tip of the shaft.

[0025] In addition, the input side cover flange includes a through hole through which the shaft passes, and a bearing may be provided between the inner wall of the through hole and the shaft.

[0026] The reducer according to the present invention simultaneously includes a planetary gear structure and a three-point driving harmonic drive, thereby preventing a dead-end state, significantly increasing the meshing ratio of teeth, and greatly improving reducer performance items such as rated torque and peak torque, while maximizing the reduction ratio.

[0027] Figure 1 is a conceptual diagram for explaining a harmonic drive, which is one component of a reducer according to the present invention.

[0028] Figures 2 to 4 are drawings showing the shape of a wave generator, which is a component of the harmonic drive illustrated in Figure 1.

[0029] Figure 5 is a drawing showing a state in which the wave generator illustrated in Figure 1 is installed on a flex spline.

[0030] Figure 6 is a drawing showing a state in which the flex spline illustrated in Figure 5 is installed on a circular spline.

[0031] Figure 7 is a drawing for explaining a deceleration operation by a harmonic drive, which is a component of a reducer according to the present invention.

[0032] Figures 8 and 9 are internal structural drawings and front views of a harmonic drive, which is a three-point drive reducer in a reducer according to the present invention.

[0033] Figures 10 and 11 illustrate a structure in which a harmonic drive, which is a three-point drive reducer, and a planetary gear structure are combined in a reducer according to the present invention.

[0034] Figures 12 and 13 illustrate a structure in which a harmonic drive, which is a three-point drive reducer, and a bevel gear are combined in a reducer according to the present invention.

[0035] Figures 14 to 17 are drawings in which a reducer according to the present invention is applied to a multi-joint robot.

[0036] The following detailed description of the present invention refers to the accompanying drawings, which illustrate specific embodiments in which the present invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the present invention. It should be understood that the various embodiments of the present invention, while different from each other, are not necessarily mutually exclusive. For example, specific shapes, structures, and characteristics described herein may be implemented in other embodiments without departing from the spirit and scope of the present invention. Furthermore, it should be understood that the positions or arrangements of individual components within each disclosed embodiment may be modified without departing from the spirit and scope of the present invention. Accordingly, the following detailed description is not intended to be limiting, and the scope of the present invention is defined only by the appended claims, along with the full scope of equivalents to which such claims are entitled, if properly described. Like reference numerals in the drawings designate the same or similar functionality throughout the several aspects.

[0037] Hereinafter, a reducer according to an exemplary embodiment of the present invention will be described with reference to the attached drawings. The reducer according to the present invention can simultaneously perform reduction using a planetary gear structure and reduction using a three-point drive wave generator. The three-point drive wave generator coupled to the planetary gear reducer having a planetary gear structure has three protrusions formed at regular intervals on the outer surface, and the teeth of a flex spline on which the three protrusions are located are simultaneously engaged with the teeth of a circular spline.

[0038] In addition, a reducer according to another embodiment of the present invention may be implemented to enable bevel gear driving by installing a spline on the input drive shaft.

[0039] First, with reference to FIGS. 1 to 5, a three-point drive wave generator provided in a reducer according to the present invention and a harmonic drive including the same will be described.

[0040] FIG. 1 is a conceptual diagram for explaining a harmonic drive, which is one component of a reducer according to the present invention, and FIGS. 2 to 4 are drawings showing the shape of a wave generator, which is one component of the harmonic drive illustrated in FIG. 1.

[0041] Referring to FIG. 1, a harmonic drive, which is a component of a reducer according to the present invention, may include a wave generator (100), a flex spline (200), and a circular spline (300).

[0042] The wave generator (100) is formed in an overall triangular shape and is connected to an input shaft to perform rotational motion. The wave generator (100) is installed on the inside of the flex spline (200) and elastically deforms the flex spline (200) to cause the flex spline (200) to perform a decelerating rotational motion in the opposite direction.

[0043] Referring to FIGS. 2 and 3, a wave generator (100) included in a harmonic drive, which is a component of a reducer according to the present invention, includes a cam plate (110) and a ball bearing (120) formed on the outside to surround the cam plate (110).

[0044] The cam plate (110) has a circular central portion (111) and crescent-shaped protrusions (110a, 110b, 110c) formed at least five points on the outer surface of the central portion (111), and is connected to an input shaft to perform rotational movement. The crescent-shaped protrusions (110a, 110b, 110c) formed at least five points at regular intervals can correspond to the vertices of a triangle as a whole. The cam plate (110) can be formed of a rigid material that does not deform in shape.

[0045] The ball bearing (120) may be formed on the outside so that a plurality of balls (130) in a ring shape surround the cam plate (110). The inside of the ball bearing (120) may be in contact with the outside of the cam plate (110), and a portion of the outside of the ball bearing (120) may be in contact with a portion of the inside of the flex spline (200).

[0046] Since the ball bearing (120) is elastically deformed by the shape of the cam plate (110), protrusions (120a, 120b, 120c) may be formed on the outer circumferential surface corresponding to each of the protrusions (110a, 110b, 110c) of the cam plate (110). The protrusions (120a, 120b, 120c) formed at at least five points corresponding to the protrusions (110a, 110b, 110c) of the cam plate (110) are formed at regular intervals, so that they may correspond to the vertices of a triangle as a whole.

[0047] The protrusions (120a, 120b, 120c) of the ball bearing (120) elastically deform the flex spline (200) so that at least five points of the flex spline (200) come into contact with the inside of the circular spline (300), and the teeth can mesh simultaneously at the three points of contact.

[0048] In this way, since crescent-shaped protrusions are formed at least at five points on the outer surface of the circular cam plate (110), the flex spline (200) and circular spline (300) that are combined therewith can mesh with each other at three points simultaneously.

[0049] The flex spline (200) is formed in a cup shape, and a wave generator (100) can be installed on the inside. Teeth can be formed on the outer surface of the flex spline (200).

[0050] Referring to FIG. 4, each of the protrusions (110a, 110b, 110c) formed on the outer surface of the central portion (111) of a circular shape is included in three different circles and forms a part of the circles, and the diameters of the three different circles can all be formed to be the same.

[0051] The radius R2 of the three circles including each of the protrusions (110a, 110b, 110c) is smaller than the radius R1 of the central portion (111) of the circular shape, and the relationship is defined as in the following [Mathematical Formula 1].

[0052] [Mathematical Formula 1]

[0053] R2 = k × R1

[0054] Here, k is a proportional constant, and is in the range of 0.6 to 0.8, with k = 0.7 being most preferable. When k < 0.6, the overall shape of the cam plate (110) does not become a circle, so the movement of the ball (130) does not become smooth, which may cause a rotational problem. On the other hand, when k > 0.8, the overall shape of the cam plate (110) becomes almost a circle, so there is a problem that the meshing portion at the three points becomes too wide.

[0055] Figure 5 is a drawing showing a state in which the wave generator illustrated in Figure 1 is installed on a flex spline.

[0056] Referring to FIG. 5, the flex spline (200) is formed of a metal elastic body, has a wave generator (100) installed inside, and can be elastically deformed by the shape of the wave generator (100).

[0057] Among the elastically deformed portions of the flex spline (200), the portions that are elastically deformed by the protrusions (120a, 120b, 120c) of the wave generator can rotate the circular spline (300) by interlocking the teeth by contacting the inner side of the circular spline (300).

[0058] The circular spline (300) is formed in a ring shape, and a flex spline (200) can be installed on the inside. The circular spline (300) is formed of a rigid material whose shape does not change, and teeth that mesh with the teeth of the flex spline (200) can be formed on the inner surface.

[0059] The number of teeth formed on the inner surface of the circular spline (300) can be designed to be greater than the number of teeth formed on the outer surface of the flex spline (200) for the purpose of reduction ratio.

[0060] Figure 6 is a drawing showing a state in which the flex spline illustrated in Figure 5 is installed on a circular spline.

[0061] Referring to Fig. 6, a flex spline (200) is installed on the inner side of a circular spline (300) having a ring shape, and can engage teeth at at least five points (A1, A2, A3). Teeth formed on the outer surface of the flex spline, which is elastically deformed by the shape of the wave generator, can engage teeth formed on the inner surface of the circular spline.

[0062] Since the teeth formed on the outer surface of the flex spline mesh with the teeth formed on the inner surface of the circular spline at three different points at regular intervals, a deadoidal state in which the teeth are misaligned may not occur. Here, deadoidal state refers to a state in which the meshing of the teeth is shifted to one side when a ratcheting phenomenon occurs or parts are forcibly assembled. Ratcheting phenomenon refers to a state in which the meshing of the teeth between the flex spline and the circular spline is momentarily misaligned when excessive impact torque is applied during operation, even though the flex spline, etc., is not damaged.

[0063] Figure 7 is a drawing for explaining a deceleration operation by a harmonic drive, which is a component of a reducer according to the present invention.

[0064] Referring to Fig. 7, (a) the flex spline (200) is elastically deformed by the wave generator (100), and the teeth (210) located at three points are engaged with the teeth (310) formed on the inner surface of the circular spline (300), and in other areas, the teeth are completely separated.

[0065] (b) When the circular spline (300) is fixed and the wave generator (100) is rotated 90 degrees clockwise, the flex spline (200) is elastically deformed and the meshing of the teeth with the circular spline (300) moves sequentially.

[0066] (c) When the wave generator (100) rotates 180 degrees clockwise, the flex spline (200) moves counterclockwise.

[0067] (d) When the wave generator (100) rotates 360 degrees, the flex spline (200) moves counterclockwise. At this time, the flex spline (200) moves counterclockwise by the difference between the number of teeth of the flex spline (200) and the number of teeth of the circular spline (300).

[0068] In the conventional two-point drive differential reducer, when the number of teeth is two, more than 200 teeth must be formed to implement a reduction ratio of 100:1, and in the case of the three-point drive differential reducer, more than 300 teeth must be formed when the number of teeth is three. In this case, the tooth module becomes too small, so tooth processing is not easy. Considering this, the present invention utilizes a front planetary gear structure to overcome the high-ratio reduction limit while maintaining the unique characteristics and reduction ratio characteristics of the three-point drive differential reducer, thereby maximizing the reduction ratio. That is, by inserting a planetary gear reducer capable of a front reduction of 2:1 to 4:1 or more into the three-point drive differential reducer, the performance of the reducer is maximized.

[0069] FIGS. 8 and 9 are internal structural drawings and front views of a harmonic drive, which is a three-point drive reducer in a reducer according to the present invention, and FIGS. 10 and 11 illustrate a structure in which a harmonic drive, which is a three-point drive reducer, and a planetary gear structure are combined in a reducer according to the present invention.

[0070] First, referring to FIGS. 8 and 9, the reducer with the planetary gear structure omitted has an input gear shaft (400) extended in the direction of the central axis (C), and the harmonic drive structure described above is arranged between the cover flange (410) and the output flange (421).

[0071] The cover flange (410) has a hole formed through which the input gear shaft (400) passes, and the end of the input gear shaft (400) is connected to the output flange (421) through the hole. Meanwhile, a main ball bearing (402) for supporting the input gear may be provided between the cover flange (410) and the input gear shaft (400). In addition, a fixing seal (C ring) (403) for fixing the outer diameter of the input gear and the inner ring of the ball bearing (402), and a fixing seal (404) for fixing the cover flange (410) and the outer ring of the ball bearing (402) may be provided.

[0072] The harmonic drive structure is composed of a circular spline (300), a flex spline (200), and a wave generator (100) as described above, and the wave generator (100) has a ball bearing (120) including a plurality of balls (130). The inner teeth (310) of the circular spline (300) and the outer teeth (210) of the flex spline (200) can be arranged on the same plane as the wave generator (100). At this time, the wave generator (100) is a three-point drive wave generator as illustrated in FIGS. 1 to 5, and a duplicate description thereof will be omitted. The input gear shaft (400) passes through the center of the cam plate (110) of the wave generator (100) and is connected to the output side flange (421), and the output side flange (421) is provided with a ball bearing (422) for supporting the cam plate (110) of the wave generator (100) and / or the input gear shaft (400). A through hole may be formed in the center of the wave generator (110) for passing the input gear shaft (400).

[0073] More specifically, a space is formed in the output side flange (421) to accommodate a portion of the end of the input gear shaft (400), and a ball bearing (422) for supporting the cam plate (110) of the wave generator (100) and the input gear shaft (400) can be arranged to surround the end of the input gear shaft (400) within the space.

[0074] Meanwhile, a cross roller bearing (411) for supporting the output stage may be arranged between the cover flange (410) and the output side flange (421), and a fixed flange (412) for supporting the cross roller bearing and the harmonic drive structure may be arranged. The fixed flange (412) surrounds the side of the reducer according to the present invention.

[0075] One or more oil chambers (413) (two at the top and bottom in FIG. 8) may be provided between the cover flange (410) and the fixed flange (412) to prevent oil leakage. In addition, the fixed flange (412) may be provided with an oil chamber (414) to prevent oil leakage from a cross roller bearing, etc.

[0076] As illustrated in Fig. 8, a reducer including a harmonic drive has a cavity formed therein by a cover flange (410), a fixed flange (412), and an output flange (421). In the reducer according to the present invention, a planetary gear structure is arranged within the cavity, as illustrated in Figs. 10 and 11.

[0077] Referring to FIGS. 10 and 11, the output-side flange (421) is formed with a receiving space (H) for receiving the end of the input gear shaft (400). Here, the input gear tooth (401) may be directly formed on the input gear shaft (400), or the input gear tooth (401) may be fastened to the input gear shaft (400) as a separate component. Hereinafter, the input gear tooth (401) and the input gear shaft (400) will be collectively referred to as an input gear. The tip of the input gear received in the receiving space (H) of the output-side flange (421) is supported by a ball bearing (407). In other words, the ball bearing (407) is provided between the tip of the input gear and the inner surface of the receiving space (H) to ensure smooth rotation of the input gear.

[0078] Meanwhile, the cam plate (110) of the wave generator (100) may be provided with a fastening hole for fastening a spur gear (500) of a planetary gear. Although three spur gears (500a to 500c) are illustrated in FIG. 11, a greater number of spur gears may be provided. A ball bearing (408) may be provided between the cam plate (100) of the wave generator (100) and the output flange (421). Specifically, the cam plate (110) of the wave generator (100) may be provided with a cam plate extension portion (110a) extending in the direction of the output flange (421). That is, the cam plate extension portion (110a) may extend in the direction of the axis (C). In addition, the accommodation space (H) for accommodating the tip of the input gear can be formed by a side wall (421a) protruding from the output-side flange (421) toward the cover flange (410). That is, the side wall (421a) can also extend in the direction of the axis (C). Consequently, when viewed in a direction perpendicular to the axis (C), the cam plate extension (110a) and the side wall (421a) can overlap each other with a predetermined distance apart. The ball bearing (408) for supporting the cam plate of the wave generator (100) is arranged between the cam plate extension (110a) and the side wall (421a) of the output-side flange (421), thereby supporting the wave generator (100) and ensuring smooth operation thereof.

[0079] Meanwhile, the gear (401) of the input gear may be arranged to mesh with the gear (501) of the spur gear. That is, as illustrated in FIG. 11, the gears (501) of three spur gears (500a to 500c) are arranged to mesh with the gear (401) of the input gear. Accordingly, the position of the fastening hole formed in the cam plate (110) of the wave generator (100) may be determined by the diameter of the spur gears (500a to 500c), the distance between the spur gears (500a to 500c), the diameter of the input gear, and the depth of each gear (401, 501). In relation to fastening of the spur gears (500a to 500c), the cam plate (110) of the wave generator (100) and the spur gears (500a to 500c) can be connected through pin bolts (520) or the like. The pin bolts (520) pass through fastening holes formed in the cam plate (110) to rotatably fasten the spur gears (500a to 500c) to the cam plate (100).

[0080] The cover flange (410) includes a side wall (410a) protruding toward the output flange (421). In other words, the side wall (410a) can extend in the axial direction, and a ball bearing (402) for supporting the input gear can be arranged between the side wall (410a) of the cover flange (410) and the input gear. A ball bearing (402) for supporting the input gear is provided on the upper side of the input gear, a ball bearing (407) for supporting the tip of the input gear is provided on the lower side (tip) of the input gear, and a gear (401) located on the middle side of the input gear is arranged to mesh with a spur gear gear (501) of a planetary gear. By this structure, the input gear is aligned in the axial direction and can rotate freely.

[0081] Figures 12 and 13 illustrate a drive module structure in which a harmonic drive, which is a three-point drive reducer, and a bevel gear are combined in a reducer according to the present invention.

[0082] First, referring to FIG. 12, the tip of the shaft (650) in the axial direction to which the bevel gear (600) is fastened is connected to the input-side cover flange (620). The input-side cover flange (620) includes a side wall (620a) protruding in the axial direction, and the tip of the shaft (650) is received in an accommodation space (L) formed by the side wall (620a). A tapered roller bearing (610) is provided between the inner side of the accommodation space (L) and the tip of the shaft (650), thereby facilitating rotation of the shaft (650) to which the bevel gear (600) is fastened. Meanwhile, the device (reducer and / or drive module) according to the present embodiment may further include a sealing ring (611) for supporting the outer ring of the tapered roller bearing (610).

[0083] The thrust generated by employing the bevel gear (600) is received by the tapered roller bearing (610) arranged at the tip of the shaft (650). In addition, the device (reducer and / or drive module) according to the present embodiment provides an accommodation space (L) for accommodating the tapered roller bearing (610) by modifying the structure of the input side cover flange (620).

[0084] Meanwhile, a bevel gear (600) is fastened to one end of the shaft (650), and the bevel gear (600) is fixed by a U-nut (601) and a tap screw (602). The output flange (621) faces the harmonic drive including the wave generator (100) and can be arranged to have a predetermined distance. The output flange (621) includes a through hole through which the shaft (650) passes, and a bearing (603) can be provided between the inner wall of the through hole of the output flange (621) and the shaft (650). The shaft (650) passing through the through hole of the output flange (621) also passes through the through hole formed in the center of the cam plate (110) of the harmonic drive, and is ultimately accommodated in the accommodation space (L) of the input cover flange (620).

[0085] The device (reducer and / or drive module) illustrated in FIG. 12 may have a harmonic drive structure arranged closer to the output flange (621) due to a structural deformation of the input-side cover flange (620). That is, the distance between the cam plate (110) of the wave generator (100) and the output-side flange (621) may be closer than the distance between the cam plate (110) of the wave generator (100) and the input-side cover flange (620). More specifically, the input-side cover flange (620) includes a base and a protrusion (620a) protruding from the base, and the distance between the cam plate (110) of the wave generator (100) and the output-side flange (621) may be closer than the distance between the cam plate (110) of the wave generator (100) and the base of the input-side cover flange (620). Additionally, the distance between the cam plate (110) of the wave generator (100) and the output side flange (621) may be closer than the distance between the cam plate (110) of the wave generator (100) and the end of the protrusion (620a) of the input side cover flange (620).

[0086] The device (reducer and / or drive module) illustrated in Fig. 12 enables bevel gear driving by attaching a spline to the input drive shaft. Specifically, the device (reducer and / or drive module) illustrated in Fig. 12 has a structure in which, in addition to the structure of the device (reducer and / or drive module) employing the three-point support wave generator described above, a tapered roller bearing is inserted to receive the axial force of the five-axis reducer that generates thrust. In addition, the output flange (621) is designed so that the input shaft passes through it, and a structure is adopted in which the input gear can be modified to be fixed with a spline.

[0087] The device (reducer and / or drive module) illustrated in Fig. 13 is designed to enable bevel gear driving by attaching a spline to the input drive shaft in a three-point drive reducer. The device (reducer and / or drive module) illustrated in Fig. 13 is designed so that the shaft (750) passes through the input side cover flange (720), unlike the device (reducer and / or drive module) illustrated in Fig. 12. That is, a spline is formed on the input drive shaft, a bevel gear is assembled, and the bevel gear is then fixed with a unit nut. Meanwhile, a tapered roller bearing is inserted to receive the axial force generated from the bevel gear, and an ISO tool flange is attached to the end of the six-axis to improve user convenience and reduce the number of parts.

[0088] Referring to Fig. 13, a shaft (750) extends in the axial direction, a bevel gear (700) is fastened to one end of the shaft (750), and the bevel gear (700) is fixed by a U-nut (701) and a tap screw (702). An input-side cover flange (720) may be positioned to face the harmonic drive and have a predetermined distance therebetween. The input-side cover flange (720) may include a through-hole through which the shaft (750) passes, and a bearing (703) may be provided between the inner wall of the through-hole of the input-side cover flange (720) and the shaft (750). The shaft (750) passing through the through-hole of the input-side cover flange (720) also passes through a through-hole formed in the center of the cam plate (110) of the harmonic drive, and is ultimately accommodated in the accommodation space (L) of the output-side flange (721).

[0089] The tip of the shaft (750) in the axial direction to which the bevel gear (700) is fastened is connected to the output flange (721). The output flange (721) includes a side wall (721a) protruding in the axial direction, and the tip of the shaft (750) is received in a receiving space (L) formed by the side wall (721a). The side wall (721a) may be formed to a predetermined depth toward the input side cover flange (720). A tapered roller bearing (710) is provided between the inner side of the receiving space (L) and the tip of the shaft (750), thereby ensuring smooth rotation of the shaft (750) to which the bevel gear (700) is fastened. Although not shown in the drawing, a sealing ring (not shown) may be further provided to support the outer ring of the tapered roller bearing (710).

[0090] The thrust generated by employing the bevel gear (700) is received by the tapered roller bearing (710) arranged at the tip of the shaft (750). In addition, the device (reducer and / or drive module) according to the present embodiment provides a receiving space (L) to accommodate the tapered roller bearing (710) by modifying the structure of the output side flange (721).

[0091] In the device (reducer and / or drive module) illustrated in FIG. 13, the distance between the cam plate (110) of the wave generator (100) and the output side flange (721) may be closer than the distance between the cam plate (110) of the wave generator (100) and the input side cover flange (720).

[0092] Figures 14 to 17 are drawings showing a device (reducer and / or drive module) according to the present invention applied to a multi-joint robot. The device according to the present invention is a new concept drive module with high precision and high rigidity that applies a three-point drive wave generator, and can improve the low-speed vibration range, while increasing water resistance, facilitating maintenance, and dramatically extending the lifespan. Accordingly, it can be applied not only to the vertical / horizontal joint robot shown in Figure 16 but also to electric vehicles, etc., to achieve the various technical effects mentioned above. The vertical multi-joint robot to which the reducer according to the present invention can be applied is generally also called a robot arm or a manipulator. The vertical multi-joint robot has a base that rotates around an axis. The base can be equipped with a rotating body having a first joint that rotates around a first axis (Axis 1), which is a vertical axis orthogonal to the horizontal plane. A "joint" may include electromechanical elements such as a motor and a reducer that cause movement of the joint, and a sensor that detects the rotation angle of the joint (joint variable).

[0093] A vertical multi-joint robot may include a motor connection shaft connected to one end of a motor, a shaft connected to the other end of the motor connection shaft, a joint connection shaft connected to the other end of the shaft, a bevel gear formed at a tip end of the joint connection shaft, a reducer connected to the bevel gear that meshes with the bevel gear, and a joint part connected to the other end of the reducer. Here, the reducer may correspond to the reducer according to the various embodiments described above. Specifically, the bevel gear attached to the reducer illustrated in FIGS. 10, 11, 12, and 13 may mesh with the bevel gear formed at the tip end of the joint connection shaft.

[0094] The features, structures, effects, etc. described in the embodiments above are included in one embodiment of the present invention, and are not necessarily limited to that one embodiment. Furthermore, the features, structures, effects, etc. illustrated in each embodiment can be combined or modified to implement other embodiments by those skilled in the art. Therefore, the contents related to such combinations and modifications should be construed as being included within the scope of the present invention.

[0095] In addition, although the above description focuses on examples, these are merely examples and do not limit the present invention. Those skilled in the art to which the present invention pertains will appreciate that various modifications and applications not exemplified above are possible without departing from the essential characteristics of the present invention. For example, each component specifically shown in the examples can be modified and implemented. In addition, differences related to such modifications and applications should be interpreted as being included within the scope of the present invention defined in the appended claims.

Claims

1. Harmonic drive including wave generator; A plurality of spur gears connected to the cam plate of the above wave generator; and An input gear extending in the axial direction, penetrating the center of the cam plate, and gear-engaged with the plurality of spur gears; The above wave generator, A central portion of a circular shape and three protrusions formed on the outer surface of the central portion; and A reducer including a ball bearing arranged to surround the cam plate and elastically deformed by the three protrusions.

2. In paragraph 1, A cover flange including a hole through which the input gear passes; An output side flange positioned opposite the above cover flange; and A reducer including a fixed flange disposed between the cover flange and the output flange.

3. In paragraph 2, The above output side flange includes a receiving space in which the tip of the input gear is received, A reducer in which a ball bearing is arranged between the inner surface of the above-mentioned receiving space and the tip of the above-mentioned input gear.

4. In paragraph 2, The above cam plate includes a cam plate extension extending in the axial direction, A reducer having a ball bearing provided between the cam extension and the output flange.

5. In paragraph 4, The above output side flange includes a side wall protruding in the axial direction, The above ball bearing is a reducer provided between the cam plate extension and the side wall.

6. In paragraph 2, The above cover flange includes a side wall protruding in the axial direction, A reducer in which a ball bearing is arranged between the side wall of the cover flange and the input gear.

7. In paragraph 1, A reducer in which the gears of the above input gear are arranged to mesh with the gears of the above plurality of spur gears.

8. Output side flange; A harmonic drive disposed spaced apart from the output side flange and including a wave generator; A shaft extending axially and penetrating the output flange and the cam plate of the wave generator; A bevel gear connected to one end of the above shaft; and A reducer including an input side cover flange having a receiving space formed therein for receiving the other end of the shaft.

9. In paragraph 8, The above input side cover flange includes a side wall protruding in the axial direction, The above-mentioned accommodation space is a reducer formed by the side wall.

10. In paragraph 8, A reducer further comprising a tapered roller bearing arranged between the inner side of the receiving space and the tip of the shaft.

11. In paragraph 10, A reducer further comprising a C-ring supporting the above tapered roller bearing.

12. In paragraph 8, The above output side flange includes a through hole through which the shaft passes, A reducer having a bearing provided between the inner wall of the above through hole and the above shaft.

13. In paragraph 8, A reducer in which the distance between the cam plate of the wave generator and the output side flange is shorter than the distance between the cam plate and the input side cover flange.

14. Input side cover flange; A harmonic drive disposed spaced apart from the input side cover flange and including a wave generator; A shaft extending axially and penetrating the input side cover flange and the cam plate of the wave generator; A bevel gear connected to one end of the above shaft; and A reducer including an output side flange having a receiving space formed therein for receiving the other end of the shaft.

15. In paragraph 14, The above output side flange includes a side wall protruding in the axial direction, The above-mentioned accommodation space is a reducer formed by the side wall.

16. In paragraph 14, A reducer further comprising a tapered roller bearing arranged between the inner side of the receiving space and the tip of the shaft.

17. In paragraph 14, The above input side cover flange includes a through hole through which the shaft passes, A reducer having a bearing provided between the inner wall of the above through hole and the above shaft.

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