Harmonic speed reducer with double-rigid-gear structure

Abstract

The invention belongs to the technical field of harmonic speed reducers, and particularly relates to a harmonic speed reducer of a double-rigid-gear structure. According to the technical scheme, the harmonic speed reducer of the double-rigid-gear structure comprises a fixed end, an inner-tooth rigid gear is fixed to the fixed end, an output end is rotationally connected to the fixed end, an outer-tooth rigid gear is fixed to the output end, a flexible gear is arranged in the inner-tooth rigid gear, and an outer ring of the flexible gear is meshed with differential teeth of the inner-tooth rigid gear; the inner ring of the flexible gear is meshed with differential teeth of the outer-tooth rigid gear; a wave generator is further included, a cam section is arranged on the wave generator, and a flexible bearing is connected between the cam section and the inner ring of the flexible gear. According to the harmonic speed reducer of the double-rigid-gear structure, the reduction ratio is reduced under the condition that the transmission efficiency change is small, and the problem that a low-reduction-ratio harmonic speed reducer is low in transmission efficiency is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of harmonic reducers, and in particular relates to a harmonic reducer with a double rigid wheel structure. Background Art

[0002] A harmonic reducer is a gear transmission device that meets the needs of various working machines by reducing speed and increasing torque. Due to its advantages such as large transmission ratio, high load capacity, small size, light weight, low noise and high transmission accuracy, it is widely used in many industries such as aerospace, navigation, machinery manufacturing, and transportation.

[0003] A typical harmonic reducer consists of four basic components: a wave generator, a flexible gear, a rigid gear, and a flexible bearing. The wave generator, mounted on the flexible bearing, causes the flexible gear to undergo controllable elastic deformation and mesh with the rigid gear, thereby achieving motion and power transmission. For harmonic reducers of the same size, the larger the reduction ratio and the greater the number of flexspline teeth, the smaller the elastic deformation and the higher the transmission efficiency. However, the smaller the reduction ratio and the fewer the number of flexspline teeth, the greater the elastic deformation, resulting in lower transmission efficiency. Common harmonic reduction ratios include 30, 50, 80, 100, and 120. Harmonic reducers with a reduction ratio below 30 cannot be used due to their low transmission efficiency and short flexspline fatigue life. Summary of the Invention

[0004] In order to solve the above problems existing in the prior art, the purpose of the present invention is to provide a harmonic reducer with a double rigid wheel structure, which reduces the reduction ratio when the transmission efficiency changes slightly, and solves the problem of low transmission efficiency of low reduction ratio harmonic reducers.

[0005] The technical solution adopted in the present invention is: A harmonic reducer with a dual-rigid gear structure includes a fixed end with an internally toothed rigid gear fixed thereto, an output end rotatably connected thereto, an externally toothed rigid gear fixed thereto, a flexspline disposed within the internally toothed rigid gear, the outer ring of the flexspline differentially meshing with the internally toothed rigid gear; and an inner ring of the flexspline differentially meshing with the externally toothed rigid gear. The reducer also includes a wave generator equipped with a cam segment. A flexible bearing is connected between the cam segment and the inner ring of the flexspline.

[0006] The present invention adds an externally toothed rigid wheel mounted inside a conventional harmonic reducer. Teeth are provided on both the inner and outer circumferences of the flexspline. The internal teeth of the flexspline mesh with the differential teeth of the externally toothed rigid wheel, and the external teeth of the flexspline mesh with the differential teeth of the internally toothed rigid wheel. When the wave generator rotates the flexspline, the flexspline rotates at a reduced speed relative to the internally toothed rigid wheel. The newly added externally toothed rigid wheel also rotates at a reduced speed relative to the flexspline, and the rotation direction of the externally toothed rigid wheel is the same as that of the flexspline, thereby reducing the reduction ratio of the entire harmonic reducer. The present invention can reduce the reduction ratio while maintaining minimal changes in the transmission efficiency of the harmonic reducer, thereby resolving the issue of low transmission efficiency in harmonic reducers with low reduction ratios.

[0007] As a preferred solution of the present invention, the number of teeth of the outer circular teeth of the flexspline is less than that of the inner circular teeth of the rigid wheel; the number of teeth of the inner circular teeth of the flexspline is greater than that of the outer circular teeth of the rigid wheel.

[0008] As a preferred solution of the present invention, the inner ring of the flexspline includes a gear segment and a cylindrical segment.

[0009] As a preferred solution of the present invention, the gear segment of the flexspline is differentially meshed with the externally toothed rigid wheel.

[0010] As a preferred solution of the present invention, the flexible bearing is connected between the cylindrical section of the flexspline and the cam section of the wave generator.

[0011] As a preferred solution of the present invention, a cover plate is fixed to one end of the internally toothed rigid wheel away from the fixed end, and the fixed end and the cover plate limit the two ends of the flexible wheel respectively.

[0012] As a preferred solution of the present invention, rollers are provided between the fixed end and the output end. The fixed end, rollers and the output end form a cross roller bearing. The fixed end and the output end serve as the outer ring and inner ring of the cross roller bearing respectively.

[0013] As a preferred embodiment of the present invention, a sealing groove is provided between the inner ring of the cross roller bearing and the outer ring of the cross roller bearing, and an oil seal is installed in the sealing groove to seal the sealing groove.

[0014] As a preferred solution of the present invention, the output end is fixed to the external gear wheel by screws.

[0015] As a preferred solution of the present invention, the flexible spline is a circular flexible spline or other structural forms.

[0016] The beneficial effects of the present invention are: The present invention enhances a conventional harmonic reducer by adding an externally toothed rigid wheel positioned within the flexspline. Teeth are also provided on both the inner and outer circumferences of the flexspline. The internal teeth of the flexspline engage with the differential teeth of the externally toothed rigid wheel, and vice versa. When the wave generator rotates the flexspline, in addition to rotating relative to the internally toothed rigid wheel, the newly added externally toothed rigid wheel also rotates relative to the direction of the flexspline's rotation, thereby reducing the reduction ratio of the entire harmonic reducer. This invention addresses the problem of traditional harmonic reducers being unable to achieve a small transmission ratio while maintaining high efficiency by combining two reduction ratios. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural schematic diagram of the present invention; Figure 2 yes Figure 1 Cross-sectional view at AA in the middle.

[0018] In the figure: 1-fixed end; 2-inner gear; 3-output end; 4-flexible gear; 5-wave generator; 6-flexible bearing; 7-external gear; 8-cover plate; 9-oil seal; 10-roller. DETAILED DESCRIPTION

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0020] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention. It should be noted that the embodiments of the present invention and the features therein may be combined with each other unless there is a conflict.

[0021] like Figure 1 and Figure 2As shown, the harmonic reducer of the double-rigid wheel structure of this embodiment includes a fixed end 1, an internally toothed rigid wheel 2 is fixed on the fixed end 1, an output end 3 is rotatably connected in the fixed end 1, an externally toothed rigid wheel 7 is fixed on the output end 3, the outer ring of the externally toothed rigid wheel 7 is differentially meshed with the inner ring gear segment of the flexible wheel 4, the flexible wheel 4 is arranged in the internally toothed rigid wheel 2, the fixed end 1 and the cover plate 8 are respectively fixed at both ends of the internally toothed rigid wheel 2 to limit the axial position of the flexible wheel 4, and the outer ring of the flexible wheel 4 is differentially meshed with the inner ring of the internally toothed rigid wheel 2; it also includes a wave generator 5, a cam segment is provided on the wave generator 5, and a flexible bearing 6 is connected between the cam segment and the inner ring of the flexible wheel 4;.

[0022] Both the internally toothed rigid wheel 2 and the externally toothed rigid wheel 7 are circular ring structures. The inner surface of the internally toothed rigid wheel 2 is provided with teeth, while the outer surface of the externally toothed rigid wheel 7 is provided with teeth. The flexspline 4 is provided with teeth on both its inner and outer surfaces. The inner teeth of the flexspline 4 engage in differential meshing with the outer teeth of the externally toothed rigid wheel 7, while the outer teeth of the flexspline 4 engage in differential meshing with the inner teeth of the internally toothed rigid wheel 2. The outer teeth of the flexspline 4 have fewer teeth than those of the internally toothed rigid wheel 2; the inner teeth of the flexspline 4 have more teeth than those of the outer teeth of the externally toothed rigid wheel 7. The inner ring of the flexible bearing 6 is fixed to the wave generator 5, and the outer ring of the flexible bearing 6 is rotatably connected to the inner ring of the flexspline 4. The flexspline 4 is a circular ring-shaped flexspline or other structural form.

[0023] The present invention adds an externally toothed rigid wheel 7, located within the interior of the flexspline 4, to a conventional harmonic reducer. The flexspline 4 is also equipped with teeth on both its inner and outer surfaces. The internal teeth of the flexspline 4 engage with the externally toothed rigid wheel 7, while the external teeth of the flexspline 4 engage with the internally toothed rigid wheel 2. When the wave generator 5 drives the flexspline 4 clockwise to engage with the rotating wheel of the internally toothed rigid wheel 2, the flexspline 4 rotates counterclockwise at a reduced speed relative to the internally toothed rigid wheel 2. When the wave generator 5 drives the flexspline 4 clockwise to engage with the externally toothed rigid wheel 7, the externally toothed rigid wheel 7 further decelerates counterclockwise relative to the flexspline 4. The combined effect of these two reduction ratios reduces the overall reduction ratio. The present invention solves the problem of harmonic reducers being unable to achieve a small transmission ratio and high efficiency by combining these two reduction ratios.

[0024] It should be noted that the outer gear wheel 7 and the flexible bearing 6 correspond to the gear segment and cylindrical segment of the inner ring of the flexible wheel 4, respectively. The axial length of the flexible wheel 4 is slightly shorter than that of the inner gear wheel 2. Therefore, there is an axial gap between the flexible wheel 4 and the fixed end 1 and the cover plate 8, and the wave generator 5 can drive the flexible wheel 4 to rotate circumferentially. Among them, a roller 10 is provided between the fixed end 1 and the output end 3. The fixed end 1, the roller 10 and the output end 3 form a cross roller bearing, with the fixed end 1 serving as the outer ring of the cross roller bearing and the output end 3 serving as the inner ring of the cross roller bearing. The inner gear wheel 2 is fixed to the outer ring of the cross roller bearing, and the inner ring of the cross roller bearing is fixed to the outer gear wheel 7. A sealing groove is provided between the inner ring of the cross roller bearing and the outer ring of the cross roller bearing, and an oil seal 9 is installed in the sealing groove. The oil seal 9 seals the sealing groove.

[0025] Working principle: The wave generator 5 is driven to rotate by the power source, and the flexspline 4, under the action of the wave generator 5, transforms into an elliptical shape, causing the major axis of the flexspline 4 to fully engage with the internal gear 2, the minor axis to completely disengage, and the remaining teeth to be in either an "engaged" or "disengaged" state depending on the direction of rotation. Because the outer teeth of the flexspline 4 have fewer teeth than the inner gear 2, as the wave generator 5 rotates continuously, the engagement and disengagement areas of the inner gear 2 change sequentially with the phase shift of the major and minor axes of the ellipse, causing the flexspline 4 to rotate at a reduced speed relative to the stationary inner gear 2 in the direction opposite to the wave generator 5. Simultaneously, because the inner teeth of the flexspline 4 have more teeth than the outer gear 7, as the flexspline 4 rotates continuously, the engagement and disengagement areas of the outer gear 7 change sequentially with the phase shift of the major and minor axes of the ellipse, also causing the outer gear 7 to rotate at a reduced speed in the direction opposite to the wave generator 5. This combined effect results in a lower reduction ratio.

[0026] The present invention is not limited to the above-mentioned optional implementation modes. Anyone can derive other forms of products under the inspiration of the present invention. However, no matter what changes are made in the shape or structure, any technical solution that falls within the scope defined by the claims of the present invention falls within the scope of protection of the present invention.

Claims

1. A harmonic reducer with a double rigid wheel structure, characterized by: The invention comprises a fixed end (1), an inner gear wheel (2) is fixed on the fixed end (1), an output end (3) is rotatably connected in the fixed end (1), an outer gear wheel (7) is fixed on the output end (3), a flexible wheel (4) is arranged in the inner gear wheel (2), the outer ring of the flexible wheel (4) is differentially meshed with the inner gear wheel (2), and the inner ring of the flexible wheel (4) is differentially meshed with the outer gear wheel (7); and a wave generator (5) is also included, a cam segment is arranged on the wave generator (5), and a flexible bearing (6) is connected between the cam segment and the inner ring of the flexible wheel (4).

2. The harmonic reducer with a double rigid wheel structure according to claim 1, characterized in that: The number of teeth of the outer circular teeth of the flexible wheel (4) is less than the number of teeth of the inner circular teeth of the rigid wheel (2); the number of teeth of the inner circular teeth of the flexible wheel (4) is greater than the number of teeth of the outer circular teeth of the rigid wheel (7).

3. The harmonic reducer with a double rigid wheel structure according to claim 1, characterized in that: The inner ring of the flexible wheel (4) comprises a gear section and a cylindrical section.

4. The harmonic reducer with a double rigid wheel structure according to claim 3, characterized in that: The gear segment of the flexible wheel (4) is differentially meshed with the externally toothed rigid wheel (7).

5. The harmonic reducer with a double rigid wheel structure according to claim 3, characterized in that: The flexible bearing (6) is connected between the cylindrical section of the flexspline (4) and the cam section of the wave generator (5).

6. The harmonic reducer with a double rigid wheel structure according to claim 1, characterized in that: A cover plate (8) is fixed to one end of the internal gear wheel (2) away from the fixed end (1), and the fixed end (1) and the cover plate (8) respectively limit the two ends of the flexible wheel (4).

7. The harmonic reducer with a double rigid wheel structure according to claim 1, characterized in that: A roller (10) is provided between the fixed end (1) and the output end (3); the fixed end (1), the roller (10) and the output end (3) form a cross roller bearing; the fixed end (1) and the output end (3) serve as the outer ring and inner ring of the cross roller bearing, respectively.

8. The harmonic reducer with a double rigid wheel structure according to claim 7, characterized in that: A sealing groove is provided between the inner ring of the cross roller bearing and the outer ring of the cross roller bearing, and an oil seal (9) is installed in the sealing groove.

9. The harmonic reducer with a double rigid wheel structure according to claim 1, characterized in that: The output end (3) and the outer gear wheel (7) are fixed by screws.

10. A harmonic reducer with a double rigid wheel structure according to any one of claims 1 to 9, characterized in that: The flexible wheel (4) is a circular flexible wheel.

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