Double-outer-ring flexible bearing, wave generator and harmonic reducer

Abstract

The invention discloses a double-outer-ring flexible bearing, a wave generator and a harmonic reducer. Comprising a bearing inner ring, a first bearing outer ring, a second bearing outer ring and rolling bodies, raceways are arranged on the outer peripheral wall of the bearing inner ring and the inner peripheral wall of the first bearing outer ring; the outer ring of the second bearing is nested on the outer wall of the outer ring of the first bearing, and the contact area of the outer peripheral wall of the outer ring of the first bearing and the inner peripheral wall of the outer ring of the second bearing is a partial spherical surface matched in shape; the width of the first bearing outer ring is 30-80% of that of the second bearing outer ring; when the first bearing outer ring and the second bearing outer ring are assembled, elastic deformation of a thin wall is utilized, the first bearing outer ring and the second bearing outer ring are arranged in a staggered and sleeved mode at an angle and then assembled into a nested structure in a rotating mode, and axial disengagement in the coaxial operation process can be avoided.

Description

Technical Field

[0001] The present invention relates to the field of harmonic reducers, and in particular to a double outer ring flexible bearing, a wave generator comprising the same, and a harmonic reducer comprising the same. Background Art

[0002] Harmonic reducers are widely used in industrial robots, aerospace, precision instruments and other fields, and one of their core components is the flexible bearing. The flexible bearing in the prior art usually consists of an inner ring, an outer ring, a rolling element and a cage.

[0003] The performance of flexible bearings affects key parameters of harmonic reducers, such as starting torque, accuracy, and life. During use, many harmonic reducers have cracks in the outer ring of the flexible bearing along the raceway, causing damage. The outer ring of the flexible bearing must be continuously deformed, so the thickness cannot be too thick, especially the raceway. The contact pressure between the outer ring raceway and the roller is large, and the hardness of the flexible wheel material on the outside of the outer ring is low. The thin raceway is repeatedly deformed under the roller pressure, which can easily shorten the bearing life and thus affect the service life of the harmonic reducer. Summary of the invention

[0004] The objective of the present invention is achieved through the following technical solutions:

[0005] The first aspect of the present invention is to provide a double outer ring flexible bearing, comprising a bearing inner ring, a bearing outer ring and a rolling element; wherein the bearing outer ring is a two-layer nested structure, consisting of a first bearing outer ring and a second bearing outer ring; the rolling element is arranged between the first bearing outer ring and the bearing inner ring, at least part of the outer peripheral wall of the bearing inner ring is provided with a raceway, and the inner peripheral wall of the first bearing outer ring is provided with a raceway corresponding to the shape and position of the raceway of the bearing inner ring; the second bearing outer ring is nested in the outer wall of the first bearing outer ring, and at least part of the outer peripheral wall of the first bearing outer ring is A partial spherical surface including a spherical large circle, wherein the diameter of the spherical surface is the maximum outer diameter of the first bearing outer ring; at least a portion of the inner circumferential wall of the second bearing outer ring is a partial spherical surface including a spherical large circle, wherein the diameter of the spherical surface is the maximum outer diameter of the first bearing outer ring; and a contact area between the outer circumferential wall of the first bearing outer ring and the inner circumferential wall of the second bearing outer ring is the above-mentioned partial spherical surface; thus, when the first bearing outer ring and the second bearing outer ring are assembled, they utilize the elastic deformation of the thin wall, are firstly arranged in an angled staggered arrangement, and then are rotated and assembled into a nested structure, which can avoid axial disengagement during use.

[0006] The width of the first bearing outer ring is narrower than that of the second bearing outer ring, and the width of the first bearing outer ring is 30-80% of the width of the second bearing outer ring. Moreover, the inner wall of the first bearing outer ring is the same as the inner wall of the existing flexible bearing outer ring, and the outer peripheral wall of the second bearing outer ring is the same as the outer wall of the existing flexible bearing outer ring. The first bearing outer ring is provided with a raceway portion with a thickness greater than or equal to the thickness of the raceway portion of the existing flexible bearing outer ring; the outer peripheral wall of the first bearing outer ring is a partial spherical surface, and the thickness of its upper and lower edges is less than that of the existing flexible bearing, so that its flexible deformation stress is smaller. The thickness of the upper and lower edges of the outer peripheral wall of the second bearing outer ring is less than or equal to the existing flexible bearing outer ring. The second bearing outer ring rotates relative to the first bearing outer ring so that the first bearing outer ring and the second bearing outer ring are nested. The outer ring of a traditional flexible bearing has the function of fully supporting the tooth width area of ​​the flexible wheel, so its width is much larger than the necessary width of the raceway. However, the wider the outer ring of the flexible bearing, the greater the deformation stress and the greater the rolling resistance. Therefore, the width of the first bearing outer ring of the double outer ring flexible bearing proposed in the present invention is 30-80% of the width of the second bearing outer ring. The width of the first bearing outer ring is only sufficient to set the raceway to radially transmit pressure to the second bearing outer ring, thereby reducing the deformation stress of the first bearing outer ring.

[0007] The first bearing outer ring and the second bearing outer ring are both made of existing flexible bearing outer ring materials. Since the hardness of the second bearing outer ring is greater than that of the flexible wheel or the inner flexible wheel, the second bearing outer ring can provide better support for the raceway of the first bearing outer ring, disperse the contact stress between the first bearing outer ring and the flexible wheel or the inner flexible wheel, and reduce bearing fatigue.

[0008] The assembly of the bearing inner ring, rolling elements and the first bearing outer ring is the same as that of the existing flexible bearing. The rolling elements are placed between the bearing inner ring and the first bearing outer ring, and then the bearing retainer is used to fix the rolling element spacing.

[0009] In one embodiment, the rolling element is a ball, part of the outer wall of the inner ring of the bearing is provided with an arc groove or peach-shaped raceway, and part of the inner circumferential wall of the outer ring of the first bearing is also provided with an arc groove or peach-shaped raceway.

[0010] Furthermore, the nested assembly method of the first bearing outer ring and the second bearing outer ring of the double outer ring flexible bearing is to firstly put the second bearing outer ring on the outer peripheral wall of the first bearing outer ring at an angle, and then rotate the second bearing outer ring so that it is completely fitted on the outer peripheral wall of the first bearing outer ring.

[0011] Furthermore, the contact surface of the first bearing outer ring and / or the second bearing outer ring is a smooth surface.

[0012] Furthermore, the contact surface of the first bearing outer ring and / or the second bearing outer ring is a honed surface.

[0013] The second aspect of the present invention is to disclose a wave generator, which includes a cam and the above-mentioned double outer ring flexible bearing, and the double outer ring flexible bearing is nested outside the cam; the cam is a cam with evenly divided angles at two or more ends.

[0014] Furthermore, the wave generator is a multi-head wave generator with more than three heads, and each protrusion is equally divided along the circumference.

[0015] The third aspect of the present invention is to disclose a harmonic reducer, comprising the above-mentioned wave generator.

[0016] Moreover, the flexible wheel of the harmonic reducer is made of PEEK material.

[0017] The fourth aspect of the present invention is to disclose a double flexible-wheel harmonic reducer with limited deformation, comprising the above-mentioned wave generator. The double flexible-wheel harmonic reducer comprises an inner flexible wheel and an outer flexible wheel, and the wave generator is arranged inside the inner flexible wheel.

[0018] Moreover, the inner flexible wheel and / or the outer flexible wheel of the double flexible wheel harmonic reducer are made of PEEK material.

[0019] Related concepts

[0020] The thickness described in the present specification refers to the difference between the outer ring radius and the inner ring radius of the annular portion;

[0021] The width refers to the axial height of the annular portion. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a stereoscopic diagram of the double outer ring flexible bearing described in Example 1;

[0023] Figure 2 yes Figure 1 Cross-sectional view of a double outer ring flexible bearing;

[0024] Figure 3 yes Figure 1 Exploded diagram of a double outer ring flexible bearing;

[0025] Figure 4 yes Figure 1 Schematic diagram of the assembly of the first bearing outer ring and the second bearing outer ring of a double outer ring flexible bearing.

[0026] in,

[0027] 1: bearing inner ring; 2: first bearing outer ring; 3: second bearing outer ring; 4: roller; 5: roller cage. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions, beneficial effects and significant improvements of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the drawings provided in the examples of the present invention. Obviously, all the described embodiments are only partial embodiments of the present invention, rather than all embodiments; based on the demonstrations made in the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field based on the content, implementation methods and drawings of the present invention without making any creative work belong to the scope of protection of the present invention.

[0029] It should be noted that the terms "first", "second", "third", etc. in the specification and claims of the present invention are only used to distinguish different objects, rather than to describe a specific order.

[0030] It should also be noted that the following specific embodiments may be combined with each other, and the same or similar concepts or processes therein may not be repeated in some embodiments.

[0031] Example 1

[0032] like Figure 1-3 As shown, a double outer ring flexible bearing comprises a bearing inner ring 1, a first bearing outer ring 2, a second bearing outer ring 3, a plurality of rollers 4 and a roller cage 5. The rollers 4 are placed in the roller cage 5, and the rollers 4 are balls. The roller cage 5 is arranged between the first bearing outer ring 2 and the bearing inner ring 1, and a plurality of the rollers 4 are evenly distributed on the roller cage 5 in the circumferential direction. Moreover, the second bearing outer ring 3 is nested in the outer wall of the first bearing outer ring 2, the outer wall of the second bearing outer ring 3 is the same as the outer wall of the existing flexible bearing outer ring, and the inner wall of the bearing inner ring 1 is the same as the inner wall of the existing flexible bearing inner ring.

[0033] Moreover, an arc groove type raceway is provided on part of the outer wall of the bearing inner ring 1, and an arc groove type raceway is also provided on part of the inner peripheral wall of the first bearing outer ring 2. Of course, according to actual conditions, the raceway can also be a peach-shaped raceway.

[0034] The first bearing outer ring and the second bearing outer ring are concentric sleeve structures, which can slide and rotate relative to each other. Moreover, the width of the first bearing outer ring is narrower than that of the second bearing outer ring, and the width of the first bearing outer ring is only enough to set a raceway to radially transmit pressure to the second bearing outer ring. Part of the outer peripheral wall of the first bearing outer ring 2 and part of the inner peripheral wall of the second bearing outer ring 3 can contact, and the contact surface between the first bearing outer ring and the second bearing outer ring is a partial spherical surface.

[0035] Moreover, during assembly, the first bearing outer ring and the second bearing outer ring are firstly arranged alternately at an angle, and then the second bearing outer ring 3 located at the outermost ring is rotated relative to the first bearing outer ring 2 until they are fitted, so that the upper and lower edge positions of the first bearing outer ring and the second bearing outer ring are basically overlapped, and the fitting of the first and second bearing outer rings can avoid axial disengagement during use. The first bearing outer ring can be fitted with the second bearing outer ring after being assembled with the roller and the bearing inner ring, or the first bearing outer ring can be fitted with the second bearing outer ring before being assembled with the roller and the bearing inner ring. Moreover, the raceway portion of the first bearing outer ring 2 is equal to the thickness of the raceway portion of the existing flexible bearing outer ring of the same size; the outer side wall of the first bearing outer ring is a partial spherical structure, and the remaining portion of the first bearing outer ring 2 (i.e., the upper and lower edges along the axial direction) is less than the thickness of the corresponding position of the existing flexible bearing outer ring of the same size. The upper and lower edge thicknesses of the outer peripheral wall of the second bearing outer ring 3 are equal to the existing flexible bearing outer ring of the same size, and the total thickness of the double outer rings is greater than the thickness of the existing bearing outer ring. The first bearing outer ring 2 and the second bearing outer ring 3 are both made of existing GCr15 bearing steel.

[0036] like Figure 4 As shown, the nested assembly method of the first bearing outer ring 2 and the second bearing outer ring 3 is: firstly, the first bearing outer ring 2 is perpendicular to the second bearing outer ring 3, the second bearing outer ring 3 is cross-fitted on the outer wall of the first bearing outer ring 2, and then the second bearing outer ring 3 is rotated to make it completely fit on the outer wall of the first bearing outer ring 2. The second bearing outer ring 3 can be fitted on the first bearing outer ring 2 before the roller is assembled, or it can be fitted on the first bearing outer ring 2 after the roller is assembled. The assembly method of the bearing inner ring 1, the first bearing outer ring 2, the roller 4 and the roller retainer 5 is the same as that of the existing flexible bearing.

[0037] Example 2

[0038] A wave generator includes an elliptical cam and a double outer ring flexible bearing, the flexible bearing has the same structure as the double outer ring flexible bearing described in Example 1, and will not be described in detail here. The cam is a three-head cam, each protrusion is 120° apart, and during installation, the cam is pressed into the inner diameter of the bearing inner ring, tightly matched with the bearing inner ring, and the inner ring is deformed, so that the flexible bearing is deformed as a whole, and the outer diameter of the second outer ring also becomes a three-head convex shape.

[0039] The hardness of the first bearing outer ring 2 and the second bearing outer ring 3 are both HRC60, which is greater than the hardness of the flexible wheel. Therefore, the second bearing outer ring 3 can provide better support for the raceway of the first bearing outer ring 2, disperse the contact stress between the first bearing outer ring 2 and the flexible wheel, and reduce bearing raceway fatigue.

[0040] Example 3

[0041] A harmonic reducer includes a flexible wheel, a rigid wheel and a wave generator. The wave generator includes an elliptical cam and a double outer ring flexible bearing. The double outer ring flexible bearing has the same structure as the double outer ring flexible bearing described in Example 1, and will not be described in detail here. During installation, the cam is pressed into the inner diameter of the inner ring of the bearing, tightly fits with the inner ring of the bearing, and deforms the inner ring, so that the flexible bearing is deformed as a whole, and the outer diameter of the second outer ring also becomes an elliptical shape. The outer wall of the wave generator is sleeved with a flexible wheel, and the wave generator can make the two ends of the long axis of the flexible wheel contact with the rigid wheel and press the inner wall of the rigid wheel. The flexible wheel always maintains some teeth that continuously engage in and out of the teeth of the rigid wheel along the rotation direction of the wave generator, so it is shown that the self-rotation of the wave generator drives the flexible wheel and the rigid-flexible wheel to rotate relative to each other, achieving the speed reduction and torque increase reducer effect.

[0042] Example 4

[0043] A harmonic reducer comprises a flex spline, a rigid spline and a wave generator. The harmonic reducer is the same as that in Embodiment 3 and will not be described in detail herein. The only difference is that the flex spline is made of PEEK.

[0044] Example 5

[0045] A double flexible wheel harmonic reducer with limited deformation, comprising an inner flexible wheel, an outer flexible wheel and a wave generator. The wave generator comprises a three-head cam and a double outer ring flexible bearing, and the double outer ring flexible bearing has the same structure as the double outer ring flexible bearing described in Example 1, which will not be described in detail here. The cam is a three-head cam, and the wave generator is coaxially arranged with the inner flexible wheel and the outer flexible wheel. The outer wall of the wave generator is provided with an inner flexible wheel, and the outer wall of the inner flexible wheel is provided with an outer flexible wheel. Both the inner flexible wheel and the outer flexible wheel are made of commonly used steel for flexible wheels of existing harmonic reducers, and mutually meshing teeth are arranged on the opposite walls of the outer flexible wheel and the inner flexible wheel.

[0046] When in use, the elliptical cam can make the three ends of the outer protrusion of the inner flexible wheel mesh with the teeth on the inner wall of the outer flexible wheel and press the inner wall of the outer flexible wheel. The wave generator is provided with a keyway shaft hole connected to the input torque. The wall surface of the wave generator is against the wall surface of the inner flexible wheel. When it is actuated, the inner flexible wheel undergoes three-head elastic deformation. The inner flexible wheel always maintains some teeth that continuously mesh in and out of the teeth of the outer flexible wheel along the rotation direction of the wave generator. Therefore, the self-rotation of the wave generator drives the inner and outer flexible wheels to rotate relative to each other, thereby achieving the reducer effect of reducing speed and increasing torque.

[0047] Example 6

[0048] A double flexible wheel harmonic reducer with limited deformation includes an inner flexible wheel, an outer flexible wheel and a wave generator. The double flexible wheel harmonic reducer is the same as that in Example 5 and will not be described in detail here. The only difference is that the inner flexible wheel is made of PEEK.

[0049] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents, and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention. The non-essential improvements, adjustments or replacements made by those skilled in the art based on the contents of this specification are all within the scope of protection required by the present invention.

Claims

1. A double outer ring flexible bearing, comprising a bearing inner ring (1), a bearing outer ring and rolling elements; characterized in that: The bearing outer ring is a two-layer nested structure, consisting of a first bearing outer ring (2) and a second bearing outer ring (3); the rolling element is arranged between the first bearing outer ring (2) and the bearing inner ring (1); at least part of the outer peripheral wall of the bearing inner ring (1) is provided with a raceway; the inner peripheral wall of the first bearing outer ring (2) is provided with a raceway corresponding to the shape and position of the bearing inner ring (1); the inner surface of the second bearing outer ring (3) is in close contact with the back of the raceway of the first bearing outer ring (2); the hardness of the second bearing outer ring is greater than that of the flexspline or the inner flexspline, providing a hardness support greater than the hardness of the inner surface of the flexspline for the back of the first bearing outer ring (2), thereby reducing deformation of the raceway of the first bearing outer ring (2) under the pressure of the rolling element; The second bearing outer ring (3) is embedded in the outer peripheral wall of the first bearing outer ring (2); at least part of the outer peripheral wall of the first bearing outer ring (2) is a partial spherical surface including a spherical large circle, and the spherical surface diameter is the maximum outer diameter of the first bearing outer ring (2); at least part of the inner peripheral wall of the second bearing outer ring (3) is a partial spherical surface including a spherical large circle, and the spherical surface diameter is the maximum outer diameter of the first bearing outer ring (2); Furthermore, the contact area between the outer peripheral wall of the first bearing outer ring (2) and the inner peripheral wall of the second bearing outer ring (3) is the partial spherical surface, so that the first bearing outer ring (2) and the second bearing outer ring (3) can utilize the elastic deformation of the thin wall during assembly, firstly be arranged in an angular staggered manner, and then rotate to form a two-layer nested structure, and can avoid axial disengagement during coaxial operation; The width of the first bearing outer ring (2) is narrower than that of the second bearing outer ring (3), and the width of the first bearing outer ring (2) is 30-80% of that of the second bearing outer ring (3).

2. The double outer ring flexible bearing according to claim 1, characterized in that: The nested assembly method of the first bearing outer ring (2) and the second bearing outer ring (3) comprises: firstly, sleeve the second bearing outer ring (3) at an angle on the outer peripheral wall of the first bearing outer ring (2), and then rotate the second bearing outer ring (3) so that it is completely sleeved on the outer peripheral wall of the first bearing outer ring (2).

3. The double outer ring flexible bearing according to claim 1, characterized in that: The contact surface of the first bearing outer ring (2) and / or the second bearing outer ring (3) is a smooth surface.

4. The double outer ring flexible bearing according to claim 1, characterized in that: The contact surface of the first bearing outer ring (2) and / or the second bearing outer ring (3) is a honed surface.

5. A wave generator, characterized in that: The wave generator comprises a cam and the double outer ring flexible bearing according to claim 1, wherein the double outer ring flexible bearing is nested outside the cam; and the cam is a cam with evenly divided angles at two or more ends.

6. A harmonic reducer, characterized in that: Comprising the wave generator as claimed in claim 5.

7. The harmonic reducer according to claim 6, characterized in that: The flexible wheel of the harmonic reducer is made of PEEK material.

8. A double-flexible harmonic reducer with limited deformation, characterized in that: Comprising the wave generator as claimed in claim 5.

9. The double flexible harmonic reducer with limited deformation according to claim 8, characterized in that: The inner flexible wheel and / or the outer flexible wheel of the double flexible wheel harmonic reducer are made of PEEK material.

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