Harmonic drive

Abstract

The utility model relates to a kind of harmonic drive devices, including flexible wheel, the wave generator with rotating shaft located in the radial inner side of flexible wheel and the first bearing being arranged between flexible wheel and wave generator, lubricating grease is filled in the cavity between rotating shaft and flexible wheel, wherein, in cavity, there is lubricating grease guiding device for introducing lubricating grease to first bearing. By setting lubricating grease guiding device, lubricating grease can be stirred, effectively avoid lubricating grease accumulation in bottom, improve the heat dissipation efficiency of harmonic drive device, and guide the stirred lubricating grease into first bearing, improve lubricating efficiency, and further improve the life of the entire harmonic drive device.

Description

Technical Field

[0001] This utility model relates to a harmonic drive device, and more particularly to a high-speed harmonic drive device. Background Technology

[0002] Harmonic drives are widely used in industrial robots, aerospace, and precision instruments due to their small size, large transmission ratio, and high precision. However, the unique structure of these drives makes lubrication a key factor affecting their performance and lifespan.

[0003] In harmonic drive systems, a thin-walled bearing is designed between the wave generator and the flexspline, and a cage is also installed between the bearings. This structure makes it difficult for lubricating grease to fully penetrate the bearings during high-speed rotation, resulting in poor lubrication. Furthermore, the lubricating grease that fails to penetrate the bearings tends to accumulate under gravity, further affecting heat dissipation efficiency, exacerbating friction and wear, and ultimately shortening the service life of the harmonic drive system. Utility Model Content

[0004] The technical problem to be solved by this utility model is to provide an improved harmonic drive device, which can effectively improve the problems of poor lubrication and lubricant accumulation.

[0005] This invention solves the aforementioned problems with its harmonic drive device. The device includes a flexible wheel, a wave generator located radially inside the flexible wheel, and a first bearing positioned between the flexible wheel and the wave generator. In this invention, the cavity between the rotating shaft and the flexible wheel is filled with lubricating grease. A grease guiding device is provided within the cavity to guide the grease into the first bearing. By providing the grease guiding device, the lubricating grease is agitated, effectively preventing grease buildup at the bottom, improving the heat dissipation efficiency of the harmonic drive device, and guiding the agitated grease into the first bearing, thus improving lubrication efficiency and extending the lifespan of the entire harmonic drive device.

[0006] According to a preferred embodiment of this utility model, the lubricating grease guiding device can be a protrusion integrally formed with the rotating shaft, a disc with a guide hole, etc., as long as it can agitate the lubricating grease and prevent it from accumulating. Preferably, the lubricating grease guiding device can be designed as a guide plate ring including a guide plate and a ring body, with the inner radial side of the ring body fixedly connected to the rotating shaft. This structure is lightweight, has a small moment of inertia, higher agitation efficiency, and is simple in structure and low in cost.

[0007] According to a preferred embodiment of this utility model, the wave generator can be designed as an ellipse, and the first bearing can be a thin-walled bearing or a sliding bearing, etc. The wave generator is preferably a cam-type thin-walled bearing. Alternatively, the wave generator can also be a disc-type, contact-type, or planetary-type structure, but the cam-type thin-walled bearing structure is simpler, more stable in operation, has less flexural distortion, and stronger load-bearing capacity.

[0008] Furthermore, the pair of guide vanes with the largest outer diameter can be positioned at the location of the largest inner diameter of the flexspline. This maximizes the area swept by the guide vanes, resulting in the most agitated lubricating grease and further improving agitation and lubrication efficiency.

[0009] According to a preferred embodiment of the present invention, the guide plate is inclined at an angle of 30° to 60° to the central axis of the ring. This arrangement can effectively guide the lubricating grease to the first bearing at the operating speed of the rotating shaft.

[0010] According to a preferred embodiment of this utility model, a second bearing is disposed between the fixed housing and the rotating shaft of the harmonic drive device. The second bearing is disposed on the axial outer side of the guide plate ring (the side away from the first bearing). The radial clearance between the radial outer side of the guide plate and the flexure can be set to 0.4mm to 0.5mm, the axial clearance between the axial inner side of the guide plate (the side closer to the first bearing) and the first bearing can be set to less than 0.5mm, and the axial clearance between the axial outer side of the guide plate and the second bearing can be set to less than 0.5mm. This design ensures that the guide plate covers the cavity containing the lubricating grease as much as possible, avoiding lubricating grease accumulation as much as possible. At the same time, it ensures that the deformation of the guide plate caused by centrifugal force and thermal expansion and contraction will not interfere with the flexure, the first bearing, or the second bearing, thus preventing damage to the guide plate and improving the reliability and safety of the entire harmonic drive device.

[0011] According to a preferred embodiment of the present invention, reinforcing ribs can also be provided between the guide plates to further strengthen the guide plates, improve their strength and rigidity, and further improve the reliability and safety of the entire harmonic drive device.

[0012] According to a preferred embodiment of this invention, the guide ring is preferably made of plastic, and is fixed to the rotating shaft by adhesive bonding. Using plastic further reduces weight and the moment of inertia of the guide ring. Adhesive bonding firmly fixes the guide ring to the rotating shaft, preventing relative rotation between them and ensuring agitation efficiency. Of course, the guide ring can also be made of other materials such as metal, and can be fixed to the rotating shaft by welding or interference fit. Attached Figure Description

[0013] The present invention will now be described in more detail with reference to the accompanying drawings, but this does not limit the overall concept of the invention.

[0014] Figure 1 This is a cross-sectional view of a harmonic drive device in the prior art;

[0015] Figure 2 This is a cross-sectional view of the harmonic drive device of this utility model;

[0016] Figure 3 This is a schematic diagram of the guide ring of this utility model.

[0017] In this utility model, unless otherwise specified, "axial", "radial" and "circumferential" are all relative to the harmonic drive device. Detailed Implementation

[0018] Figure 1 A prior art harmonic drive device is shown, including a fixed housing 7', a flexible wheel 1', and a wave generator 2' including a rotating shaft 21'. A second bearing 5' is disposed between the fixed housing 7' and the rotating shaft 21', and a first bearing 3', which is a thin-walled bearing, is disposed between the flexible wheel 1' and the wave generator 2'. A cavity 6' between the rotating shaft 21' and the flexible wheel 1' is partially filled with grease for supplemental lubrication of the first bearing 3'. However, in typical applications such as industrial robots, the wave generator 2' rotates at high speeds, typically reaching 4000 to 5000 revolutions per minute, and the first bearing 3' generally has a cage, making it difficult for grease to effectively enter the first bearing 3'. Furthermore, the grease itself has high viscosity and poor flowability, further increasing the difficulty of grease entering the first bearing 3'. These problems result in only a portion of the grease participating in the lubrication of the first bearing 3', leading to poor lubrication and affecting the service life of the entire harmonic drive device. Figure 1 In the prior art shown, the remaining grease that is not used for lubrication accumulates at the bottom of the cavity 6' under the action of gravity, which causes the heat generated by gear meshing or deformation of the flexible wheel 1' to be unable to be effectively conducted, resulting in local high temperature and further reducing the service life of the harmonic drive device.

[0019] Figure 2 , Figure 3 This invention illustrates a harmonic drive device designed according to the present invention, comprising a flexible wheel 1, a wave generator 2 with a rotating shaft 21 located radially inside the flexible wheel 1, and a first bearing 3 disposed between the flexible wheel 1 and the wave generator 2. A cavity 6 between a second bearing 5 and the first bearing 3 is filled with lubricating grease. In this invention, a lubricating grease guiding device is provided in the cavity 6 for introducing lubricating grease into the first bearing 3. By providing the lubricating grease guiding device, the lubricating grease can be agitated, effectively preventing lubricating grease accumulation at the bottom, improving the heat dissipation efficiency of the harmonic drive device, and guiding the agitated lubricating grease into the first bearing 3, improving lubrication efficiency, and thus extending the lifespan of the entire harmonic drive device.

[0020] like Figure 2 , Figure 3 As shown, in an embodiment of this utility model, the lubricating grease guiding device is a guide ring 4 with a guide plate 41 and a ring body 42, the inner side of which is fixedly connected to the rotating shaft 21. In other embodiments, the lubricating grease guiding device 4 can be a protrusion integrally formed with the rotating shaft 21, a disc with a guide hole, etc., as long as it can agitate the lubricating grease and prevent it from accumulating. The advantages of using the guide ring 4 are that this structure is lighter, has a smaller moment of inertia, higher agitation efficiency, and is simpler and less expensive. Furthermore, as... Figure 2 , Figure 3 As shown, the first bearing 3 can be a thin-walled bearing, and the wave generator 2 can be an elliptical cam-type thin-walled bearing. In other embodiments, the wave generator 2 can also be a disc type, contact type, or planetary type, etc. The cam-type thin-walled bearing structure is simpler, and has stable operation, small flexural distortion, and strong load-bearing capacity.

[0021] like Figure 2 , Figure 3 As shown in the embodiment of this utility model, the guide ring 4 is made of plastic and is bonded and fixed to the rotating shaft 21. Using plastic can further reduce weight and decrease the moment of inertia of the guide ring 4. By bonding, the guide ring 4 is firmly fixed to the rotating shaft 21, and no relative rotation occurs between the two, ensuring agitation efficiency. In other embodiments, the guide ring 4 can also be made of other materials such as metal, and can also be fixed to the rotating shaft 21 by welding or interference fit.

[0022] like Figure 3 As shown, in an embodiment of this invention, the number of guide plates 41 can be set to eight, and they are evenly and in pairs arranged on the circumferential surface of the ring body 42. Each pair of guide plates 41 is centrally symmetrical about the central axis of the ring body 42. In other embodiments, the number of guide plates 41 can vary, but is preferably at least two, and is preferably arranged in pairs on both radial sides of the ring body 42 and evenly arranged on the circumferential surface of the ring body 42. Each pair of guide plates 41 is centrally symmetrical about the central axis of the ring body 42. This ensures the dynamic balance of the guide plate ring 4, and the outer diameter of the guide plates 41 can be set to be different to match the change in the inner diameter of the flexure wheel 1, thereby improving the agitation efficiency and lubrication efficiency without affecting the dynamic balance. More preferably, in other embodiments, the pair of guide plates 41 with the largest outer diameter can be arranged at the location of the largest inner diameter of the flexure wheel 1. This maximizes the area swept by the guide plates 41, resulting in the most agitated lubricating grease, further improving the agitation efficiency and lubrication efficiency.

[0023] like Figure 3As shown, in an embodiment of this invention, the guide plate 41 is inclined at a 60° angle to the central axis of the ring 42. In other embodiments, the inclination angle can be set to other angles, preferably 30° to 60°. This setting can effectively guide the lubricating grease into the first bearing 3 at the operating speed of the rotating shaft.

[0024] like Figure 2 As shown, in an embodiment of this utility model, in the fixed housing of the harmonic drive device (and...) Figure 1 The fixed housing 7' in the middle has the same structure. Figure 2 , 3 A second bearing 5 is disposed between the guide ring 4 (not shown in the image) and the rotating shaft 21. The second bearing 5 is disposed on the axially outer side of the guide ring 4 (the side away from the first bearing 3, i.e., the side away from the first bearing 3). Figure 2 (on the right side of the guide plate 41), the radial clearance between the outer radial side of the guide plate 41 and the flexible wheel 1 can be set to 0.4mm to 0.5mm, and the axial inner side of the guide plate 41 (the side closer to the first bearing 3, i.e. Figure 2 The axial clearance between the left side of the guide plate 41 and the first bearing 3 can be set to less than 0.5 mm, and the axial clearance between the outer side of the guide plate 41 and the second bearing 5 can be set to less than 0.5 mm. This design ensures that the guide plate 41 covers the cavity 6 containing the lubricating grease as much as possible, avoiding the accumulation of lubricating grease as much as possible. At the same time, it ensures that the deformation of the guide plate 41 caused by centrifugal force and thermal expansion and contraction will not interfere with components such as the flexible wheel 1, the first bearing 3, or the second bearing 5, thus preventing damage to the guide plate 41 and improving the reliability and safety of the entire harmonic drive device.

[0025] In other embodiments, reinforcing ribs may be provided between the guide plates 41 to further strengthen the guide plates 41, improve the strength and rigidity of the guide plates 41, and further improve the reliability and safety of the entire harmonic drive device.

[0026] Obviously, the above embodiments of this utility model are merely examples for clearly illustrating the present utility model, and are not intended to limit the implementation of the present utility model. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this utility model should be included within the protection scope of the claims of this utility model.

[0027] List of reference numerals

[0028] 1, 1' Flexible Wheel

[0029] 2.2' wave generator

[0030] 21, 21' Rotation axis

[0031] 3, 3' First bearing

[0032] 4. Guide ring

[0033] 41. Guide Film

[0034] 42 Rings

[0035] 5, 5' Second bearing

[0036] 6, 6' cavity

[0037] 7' Fixed housing

Claims

1. A harmonic drive device, comprising a flexible wheel (1), a wave generator (2) with a rotating shaft (21) located radially inside the flexible wheel (1), and a first bearing (3) disposed between the flexible wheel (1) and the wave generator (2), wherein, The cavity (6) between the rotating shaft (21) and the flexible wheel (1) is filled with lubricating grease, wherein a lubricating grease guiding device for introducing lubricating grease into the first bearing (3) is provided in the cavity (6).

2. The harmonic drive device according to claim 1, characterized in that, The lubricating grease guiding device is a guide plate ring (4) having a guide plate (41) and a ring body (42), wherein the inner radial side of the ring body (42) is fixedly connected to the rotating shaft (21).

3. The harmonic drive device according to claim 2, characterized in that, The number of guide pieces (41) is at least two. The guide pieces (41) are arranged in pairs on the circumferential surface of the ring body (42). Each pair of guide pieces (41) is centrally symmetrical about the central axis of the ring body (42).

4. The harmonic drive device according to claim 3, characterized in that, The pair of guide plates (41) with the largest outer diameter are located at the location with the largest inner diameter of the flexible wheel (1).

5. The harmonic drive device according to claim 2, characterized in that, The guide piece (41) is inclined at an angle of 30° to 60° to the central axis of the ring (42).

6. The harmonic drive device according to claim 2, characterized in that, The radial gap between the outer radial side of the guide plate (41) and the flexible wheel (1) is 0.4 mm to 0.5 mm.

7. The harmonic drive device according to claim 2, characterized in that, A second bearing (5) is arranged between the fixed housing of the harmonic drive device and the rotating shaft (21). The second bearing (5) is arranged on the outer side of the guide ring (4). The axial gap between the inner side of the guide ring (41) and the first bearing (3) is less than 0.5 mm. The axial gap between the outer side of the guide ring (41) and the second bearing (5) is less than 0.5 mm.

8. The harmonic drive device according to claim 2, characterized in that, The guide pieces (41) have reinforcing ribs between them.

9. The harmonic drive device according to claim 2, characterized in that, The guide ring (4) is made of plastic and is bonded to the rotating shaft (21).

10. The harmonic drive device according to claim 1, characterized in that, The lubricating grease guiding device is a disc with a guide hole fixed on the rotating shaft (21).

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