Flexible gear, harmonic speed reducer and industrial robot

Abstract

The utility model discloses a flexible gear, harmonic speed reducer and industrial robot belongs to transmission device technical field, flexible gear includes barrel, barrel is provided with external tooth portion, external tooth portion includes a plurality of external teeth that are arranged along barrel peripheral wall at interval, each external tooth one end that connects with barrel is the root, one end that is far away from the root is the top, and the top is the top. The tooth surface of each outer tooth comprises a first cambered surface, a second cambered surface and a third cambered surface which are sequentially connected from top to root, the first cambered surfaces are tangent to the second cambered surfaces, the second cambered surfaces are tangent to the third cambered surfaces, the cambered surfaces are beneficial to reducing friction, the outer tooth part of the flexible gear and the inner tooth part of the rigid gear can be meshed more smoothly, the friction torque is lower under the same torsional rigidity, and the service life of the flexible gear is prolonged. And therefore, the transmission efficiency is improved, the transmission device is suitable for the harmonic speed reducer, and the output performance of the harmonic speed reducer is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of reducer equipment, in particular to a flexible wheel, a harmonic reducer and an industrial robot. Background Art

[0002] The harmonic reducer transmits motion through the meshing between teeth. When the wave generator is running, the flexible wheel will be forced to produce periodic elastic deformation. During this deformation process, the outer teeth of the flexible wheel will mesh with the inner teeth of the rigid wheel. Since the flexible wheel is a thin-walled structure and the meshing area between the outer teeth and the inner teeth is large, it is easy to generate large friction between the rigid wheel and the flexible wheel, resulting in a high friction torque, thereby reducing the meshing efficiency between the flexible wheel and the rigid wheel and reducing the output performance of the harmonic reducer. Utility Model Content

[0003] The utility model aims to solve at least one of the technical problems existing in the prior art. To this end, the utility model provides a flexible wheel, which can make the meshing of the flexible wheel and the rigid wheel smoother, effectively reduce the friction torque, and improve the meshing efficiency.

[0004] The utility model also provides a harmonic reducer and an industrial robot including the flexible wheel.

[0005] The flexible wheel according to the first aspect of the utility model is applied to a harmonic reducer and includes a cylinder, the cylinder is provided with an external tooth portion, the external tooth portion includes a plurality of external teeth arranged at intervals along the outer peripheral wall of the cylinder, the end of each external tooth connected to the cylinder is a root, and the end away from the root is a top, the tooth surface of the external tooth includes a first arc surface, a second arc surface and a third arc surface connected in sequence from the top to the root, the first arc surface is tangent to the second arc surface, and the second arc surface is tangent to the third arc surface.

[0006] The flexible wheel according to the embodiment of the utility model has at least the following beneficial effects:

[0007] The cylinder of the flexible wheel is provided with an external tooth portion, and the tooth surface of each external tooth in the external tooth portion includes a first arc surface, a second arc surface and a third arc surface connected to each other. The first arc surface, the second arc surface and the third arc surface are distributed in sequence from the top to the root of the external tooth, and the first arc surface is tangent to the second arc surface, and the second arc surface is tangent to the third arc surface, so that the tooth surface of the external tooth is composed of a combination of multiple arc surfaces. The arc surface is conducive to reducing friction, and can make the external tooth portion of the flexible wheel and the internal tooth portion of the rigid wheel mesh more smoothly. Under the same torsional stiffness, the friction torque is lower and the meshing efficiency is higher, thereby improving the transmission efficiency. It is suitable for harmonic reducers and is conducive to improving the output performance of harmonic reducers.

[0008] According to some embodiments of the present invention, the first arc surface, the second arc surface and the third arc surface are respectively circular arc surfaces.

[0009] According to some embodiments of the utility model, the reduction ratio of the harmonic reducer is I, the center of the cylinder is the center of the circle, the distance between the tangent point of the first arc surface and the second arc surface and the center of the circle is the first radius, the first radius is Rd1, the pitch circle radius of the flexible wheel is df, the module of the flexible wheel is m, and it satisfies: when I<80:1, Rd1=df+0.3*m.

[0010] According to some embodiments of the utility model, the reduction ratio of the harmonic reducer is I, the center of the cylinder is the center of the circle, the distance between the tangent point of the second arc surface and the third arc surface and the center of the circle is the second radius, the second radius is Rd2, the pitch circle radius of the flexible wheel is df, and the module of the flexible wheel is m, satisfying: when I<80:1, Rd2=df-0.3*m.

[0011] According to some embodiments of the utility model, the reduction ratio of the harmonic reducer is I, the center of the cylinder is the center of the circle, the distance between the tangent point of the first arc surface and the second arc surface and the center of the circle is the first radius, the first radius is Rd1, the pitch circle radius of the flexible wheel is df, and the module of the flexible wheel is m, satisfying: when I≥80:1, Rd1=df+0.454*m.

[0012] According to some embodiments of the utility model, the reduction ratio of the harmonic reducer is I, the center of the cylinder is the center of the circle, the distance between the tangent point of the second arc surface and the third arc surface and the center of the circle is the second radius, the second radius is Rd2, the pitch circle radius of the flexible wheel is df, and the module of the flexible wheel is m, satisfying: when I≥80:1, Rd2=df-0.454*m.

[0013] According to some embodiments of the present invention, the reduction ratio of the harmonic reducer is I, the arc length of the second arc surface is L2, and the aperture of the inner hole of the flexible wheel is d, satisfying: when I<80:1, 0.04*d≤L2≤0.052*d.

[0014] According to some embodiments of the present invention, the reduction ratio of the harmonic reducer is I, the arc length of the second arc surface is L2, and the aperture of the inner hole of the flexible wheel is d, satisfying: when I≥80:1, 0.138*d≤L2≤0.162*d.

[0015] According to some embodiments of the utility model, the reduction ratio of the harmonic reducer is I, along the circumference of the flexible wheel, the width of the external tooth at the pitch circle position of the flexible wheel is t1, and the module of the flexible wheel is m, satisfying: when I<80:1, 0.52*Ln(m)+0.86mm≤t1≤0.62*Ln(m)+0.98mm.

[0016] According to some embodiments of the utility model, the reduction ratio of the harmonic reducer is I, along the circumference of the flexible wheel, the width of the external tooth at the pitch circle position of the flexible wheel is t1, and the module of the flexible wheel is m, satisfying: when I≥80:1, 0.29*Ln(m)+0.68mm≤t1≤0.39*Ln(m)+0.98mm.

[0017] According to the harmonic reducer of the second aspect embodiment of the utility model, it includes a rigid wheel, a wave generator and the flexible wheel described in the first aspect embodiment, the rigid wheel has an inner tooth portion; the flexible wheel is installed in the inner hole of the rigid wheel; the wave generator is installed on the inner side of the flexible wheel, and the wave generator is configured to make the outer tooth portion mesh with the inner tooth portion when rotating.

[0018] The harmonic reducer according to the embodiment of the utility model has at least the following beneficial effects:

[0019] The harmonic reducer uses the flexible wheel of the above embodiment. Since the tooth surface of the external tooth is composed of a plurality of arc surfaces, the arc surface is conducive to reducing friction, and can make the external tooth portion of the flexible wheel and the internal tooth portion of the rigid wheel mesh more smoothly. Under the same torsional stiffness, the friction torque is lower and the meshing efficiency is higher, thereby improving the transmission efficiency and helping to improve the output performance of the harmonic reducer.

[0020] The industrial robot according to the embodiment of the third aspect of the utility model includes the harmonic reducer described in the second aspect.

[0021] Since the industrial robot includes the harmonic reducer of the above embodiment, it has at least the above beneficial effects, which will not be described in detail here.

[0022] Additional aspects and advantages of the present invention will be given in part in the following description, and in part will become apparent from the following description, or will be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The present invention is further described below with reference to the accompanying drawings and embodiments, wherein:

[0024] Figure 1 It is a front structural schematic diagram of the flexible wheel of some embodiments of the utility model;

[0025] Figure 2 for Figure 1 A schematic diagram of the enlarged structure at A in the middle;

[0026] Figure 3 It is a front structural schematic diagram of the flexible wheel of other embodiments of the utility model;

[0027] Figure 4 for Figure 3A schematic diagram of the enlarged structure at B in the middle;

[0028] Figure 5 It is a front structural schematic diagram of a harmonic reducer of some embodiments of the utility model;

[0029] Figure 6 for Figure 5 Schematic diagram of the enlarged structure at C in the middle;

[0030] Figure 7 It is a schematic diagram of the cross-sectional structure of the harmonic reducer of some embodiments of the utility model;

[0031] Figure 8 This is a driving speed comparison effect diagram of the harmonic reducer of the utility model and the traditional harmonic reducer;

[0032] Fig. 9 This is a transmission efficiency comparison diagram between the harmonic reducer of the utility model and the traditional harmonic reducer.

[0033] Reference numerals:

[0034] Harmonic reducer 10;

[0035] Flexspline 100; cylinder 110; inner hole 111; outer tooth portion 120; outer tooth 121; first arc surface 1211; second arc surface 1212; third arc surface 1213; connecting portion 130; flange portion 140;

[0036] The wheel 200; the inner tooth portion 210; the inner tooth 211;

[0037] Wave generator 300; flexible bearing 310; cam 320;

[0038] The first circle S1; the second circle S2; the pitch circle S3. DETAILED DESCRIPTION

[0039] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0040] In the description of the present invention, it should be understood that the descriptions involving orientations, such as the front, rear, circumferential, axial, radial, etc., and the orientations or positional relationships indicated are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0041] In the description of the utility model, if there is a description of first and second, it is only for the purpose of distinguishing the technical features, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0042] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0043] The harmonic reducer transmits motion through the meshing between teeth. Since the flexible wheel is a thin-walled structure, it presents the same shape as the cam after the wave generator is assembled. During the operation of the wave generator, the end face of the flexible wheel presents a periodic bell-mouth deformation. The end face of the flexible wheel is a curved surface. There is periodic circumferential motion and axial movement between the outer ring of the flexible bearing and the inner wall of the flexible wheel. The outer ring of the flexible bearing and the inner wall of the flexible wheel are the friction pairs that contribute the most to the wear during the life cycle of the reducer. The wear problem of the outer ring of the flexible bearing and the inner wall of the flexible wheel seriously restricts the reliability of the harmonic reducer. At present, most of the wear here is improved by honing the inner wall of the flexible wheel and nitriding the flexible wheel. Since the meshing area between the inner teeth of the rigid wheel and the outer teeth of the flexible wheel is large during the entire movement of the harmonic reducer, and the number of meshing teeth accounts for about 30%, the effect of improving wear by using the above process is not significant. The friction torque generated between the rigid wheel and the flexible wheel is high, which reduces the meshing efficiency between the flexible wheel and the rigid wheel, thereby reducing the output performance of the harmonic reducer.

[0044] In order to improve the reliability of the harmonic reducer, the utility model proposes a flexible wheel, which can make the meshing of the flexible wheel and the rigid wheel smoother by optimizing the structure of the flexible wheel, effectively reduce the friction torque, and increase the meshing efficiency, thereby improving the reliability of the harmonic reducer. The following is a description of the flexible wheel and the harmonic reducer with specific examples in conjunction with the accompanying drawings.

[0045] Reference Figure 1 As shown, a flexible wheel 100 proposed in an embodiment of the utility model is applied to a harmonic reducer 10. Figure 1 , a front structural schematic diagram of the flexible wheel 100 is shown. The flexible wheel 100 is also called a flexible external tooth gear. The flexible wheel 100 includes a cylinder 110. The outer peripheral wall of the cylinder 110 is provided with an external tooth portion 120. When applied to the harmonic reducer 10, the inner hole 111 of the cylinder 110 is used to install the wave generator 300. The flexible wheel 100 is installed on the inner side of the rigid wheel 200, and the external tooth portion 120 can mesh with the internal tooth portion 210 of the rigid wheel 200.

[0046] Reference Figure 1 and Figure 2As shown, in the embodiment of the utility model, the external tooth portion 120 includes a plurality of external teeth 121, and the plurality of external teeth 121 are spaced apart along the outer peripheral wall of the cylinder 110, and the end of each external tooth 121 connected to the cylinder 110 is a root, and the end of each external tooth 121 away from the root is a top, and the tooth surface of the external tooth 121 includes a first arc surface 1211, a second arc surface 1212 and a third arc surface 1213, and the first arc surface 1211, the second arc surface 1212 and the third arc surface 1213 are arranged in sequence from the top to the root, wherein the first arc surface 1211 is tangent to the second arc surface 1212, and the second arc surface 1212 is tangent to the third arc surface 1213.

[0047] Reference Figure 2 As shown, the tangent point of the first arc surface 1211 and the second arc surface 1212 is P1, the first arc surface 1211 and the second arc surface 1212 are tangent at P1, and the tangent line of the first arc surface 1211 at P1 coincides with the tangent line of the second arc surface 1212 at P1, that is, the first arc surface 1211 and the second arc surface 1212 have only one common point at P1, indicating that the distance between the first arc surface 1211 and the second arc surface 1212 at the tangent point P1 approaches zero, and outside the tangent point P1, the first arc surface 1211 and the second arc surface 1212 do not overlap. Similarly, the point of intersection of the second arc surface 1212 and the third arc surface 1213 is P2, and the tangent line of the second arc surface 1212 at P2 coincides with the tangent line of the third arc surface 1213 at P2, that is, the second arc surface 1212 and the third arc surface 1213 have only one common point at P2, indicating that the distance between the second arc surface 1212 and the third arc surface 1213 at the point of intersection P2 approaches zero, and outside the point of intersection P2, the second arc surface 1212 and the third arc surface 1213 do not overlap.

[0048] The first arc surface 1211 and the second arc surface 1212 are tangent to each other as an example for explanation. Figure 2 The tangent line L shown in is the tangent line between the first curved surface 1211 and the second curved surface 1212 at P1, and the tangent lines of the two surfaces have the same direction and overlap. It can be understood that when the first curved surface 1211 and the second curved surface 1212 are connected in a tangent manner, the two surfaces are in the same plane, and the tangent lines of the two surfaces have the same direction at the tangent point. This tangent manner can ensure the flatness between the first curved surface 1211 and the second curved surface 1212, so that the two curved surfaces can have a smooth transition.

[0049] Reference Figure 2 As shown, for ease of understanding, the arc lengths of the first arc surface 1211, the second arc surface 1212, and the third arc surface 1213 are indicated. Figure 2 The arc AB indicated in the figure represents the first arc surface 1211, the arc CD represents the second arc surface 1212, and the arc EF represents the third arc surface 1213. The first arc surface 1211, the second arc surface 1212 and the third arc surface 1213 are tangent to each other in sequence from the top to the root.

[0050] It should be noted that each external tooth 121 includes two side surfaces along the circumference of the flexible wheel 100, and the two side surfaces are symmetrically arranged with the center line as the symmetry axis. Therefore, each external tooth 121 has a first arc surface 1211, a second arc surface 1212 and a third arc surface 1213 on both sides, and the first arc surface 1211, the second arc surface 1212 and the third arc surface 1213 on both sides are respectively arranged in an axisymmetric manner.

[0051] It can be understood that the tooth surface of the external tooth 121 is composed of a first arc surface 1211, a second arc surface 1212 and a third arc surface 1213, and adjacent arc surfaces are connected in a tangential manner; relative to the external tooth 121 with a straight tooth surface, the tooth surface of the external tooth 121 in the embodiment of the utility model is smoother, and the arc surface is beneficial to reducing friction. In addition, since the third arc surface 1213 is located at the root of the external tooth 121, the roots of adjacent external teeth 121 are transitionally connected through the third arc surface 1213, that is, the tooth surface between adjacent external teeth 121 is an arc surface, so that the tooth surface of the external tooth 121 and the position of adjacent external teeth 121 are all arc surfaces. When the inner teeth 211 of the rigid wheel 200 mesh with the outer teeth 121 of the flexible wheel 100, the meshing is smoother, the friction torque is lower under the same torsional stiffness, and the meshing efficiency is higher, ensuring that the rigid wheel 200 and the flexible wheel 100 can rotate smoothly, improving the transmission efficiency, and being beneficial to improving the output performance of the harmonic reducer 10, and achieving better power transmission and deceleration effects.

[0052] Reference Figure 2 As shown, in the embodiment of the utility model, the first arc surface 1211, the second arc surface 1212 and the third arc surface 1213 are all arc surfaces, that is, the tooth surface of each external tooth 121 is composed of multiple arc surfaces. It can be understood that the external tooth 121 contacts the internal tooth 211 through multiple arc surfaces, which is conducive to further reducing friction, and the relative curvature radius is large. Compared with the involute tooth profile gear of the same material and the same size, it can significantly reduce the contact stress, thereby improving the load-bearing capacity of the flexible wheel 100.

[0053] Moreover, when the outer teeth 121 are meshing with the inner teeth 211, the contact point of the arc surface of the outer teeth 121 moves in the direction of the tooth width, so that the force is more uniform during the transmission process, thereby reducing vibration and noise, improving the smoothness of the transmission, and increasing the meshing efficiency. The larger contact area of ​​the arc surface is conducive to the formation of oil film between the tooth surfaces, reducing friction losses, lowering friction torque, and increasing transmission efficiency.

[0054] The harmonic reducer 10 is a precision transmission component. The transmission principle of the harmonic reducer 10 is a small tooth difference transmission. The wave generator 300 can be used as an input end. The wave generator 300 can include a flexible bearing 310 and a cam 320 assembled in the flexible bearing 310. The wave generator 300 is assembled in the inner hole 111 of the flexible wheel 100. The inner wall of the flexible wheel 100 and the outer ring of the flexible bearing 310 are friction pairs. The rigid wheel 200 is assembled on the outside of the flexible wheel 100. There is relative motion between the rigid wheel 200 and part of the teeth of the flexible wheel 100, which are friction pairs. The tooth meshing rate is related to the working conditions. The rigid wheel 200 is fixed, and the flexible wheel 100 can be used as an output end. The reduction ratio I=(the number of teeth of the flexible wheel 100-the number of teeth of the rigid wheel 200) / the number of teeth of the flexible wheel 100. The reduction ratio of the harmonic reducer can be achieved by changing the number of gears and the module of the gears of the inner gear portion 210 and the outer gear portion 120, so its reduction ratio is variable. This variability enables the harmonic reducer to adapt to different application requirements.

[0055] It should be noted that the harmonic reducer 10 of the embodiment of the utility model is applied to an industrial robot, and has a relatively short design dimension in axial length, and the opening angle of the flexible wheel 100 is relatively large after the wave generator 300 is pressed in. The flexible wheel 100 of the conventional harmonic reducer 10 is an involute gear. Compared with the conventional structure, the embodiment of the utility model designs multiple sections of tangent arc surfaces and a conjugate rigid wheel 200 tooth shape, so that the friction of the gears in meshing in and out is smoother, the friction force is reduced, the efficiency is improved, and the wear is reduced.

[0056] Since the reduction ratio of the harmonic reducer 10 is related to the number of teeth and the module of the flexible wheel 100 and the rigid wheel 200, the number of teeth of the flexible wheel 100 and the number of teeth of the rigid wheel 200 are related to the proportion of the meshing tooth pairs, which affects the tooth meshing rate and transmission efficiency. Therefore, the reduction ratio of the harmonic reducer 10 and the module of the flexible wheel 100 need to be considered when optimizing the structure of the flexible wheel 100; and the flexible wheel 100 is an external gear, and the pitch circle of the gear is an important reference circle in the design, manufacture and calculation of the gear. Therefore, the pitch circle of the flexible wheel 100 also needs to be considered when designing the flexible wheel 100. The diameter of the pitch circle is equal to the product of the number of teeth and the module, that is, d=mz. The pressure angle on the pitch circle is a standard value, which helps to ensure the stability and accuracy of the gear transmission. The pitch circle size of each gear angle is fixed and unchanged, and is related to the number of teeth and the module of the gear.

[0057] Reference Figure 1 and Figure 2As shown, specifically, the reduction ratio of the harmonic reducer 10 is I, with the center of the cylinder 110 as the circle center O, the tangent points P1 of the first arc surface 1211 and the second arc surface 1212 of all the external teeth 121 are connected to form a first circle S1, and the tangent points P2 of the second arc surface 1212 and the third arc surface 1213 of all the external teeth 121 are connected to form a first circle S2, the pitch circle of the flexible wheel 100 is S3, the distance between the tangent point P1 and the circle center O is the first radius Rd1, and the distance between the tangent point P2 and the circle center O is the first radius Rd2. The distance between them is the second radius Rd2, the pitch circle radius of the flexible wheel 100 is df, and the module of the flexible wheel 100 is m, which satisfies: when I<80:1, Rd1=df+0.3*m. It can be understood that the first radius Rd1 is the distance between the tangent point P1 and the circle O, that is, the distance between the tangent point P1 and the circle O can be determined by the radius and module of the pitch circle of the flexible wheel 100, so that the connection position of the first arc surface 1211 and the second arc surface 1212 can be determined.

[0058] In the embodiment of the utility model, it is also satisfied that: when I<80:1, Rd2=df-0.3*m, the difference between the first radius Rd1 and the second radius Rd2 is 0.6*m, the second radius Rd2 is the distance between the tangent point 2 and the circle O, and the distance between the tangent point P2 and the circle O can be determined by the radius and module of the pitch circle of the flexible wheel 100, so that the connection position of the second arc surface 1212 and the third arc surface 1213 can be determined.

[0059] The module of the flexible wheel 100 represents a quantity of the tooth profile size of the external tooth portion 120, and is directly related to the pitch and number of teeth of the external tooth portion 120. The size of the module determines the size and load-bearing capacity of the external tooth portion 120. The module of the flexible wheel 100 can be calculated using the following formula, which is expressed as: m=p / π, wherein m is the module and p is the pitch. Figure 2 As shown, the tooth pitch p is measured on the pitch circle. It is understandable that the larger the module, the larger the tooth profile of the outer tooth portion 120, the stronger the load-bearing capacity, but it will also increase the weight and manufacturing cost of the gear. On the contrary, the smaller the module, the smaller the outer tooth portion 120, which is suitable for occasions where space is limited or weight needs to be reduced, but its load-bearing capacity will also be reduced accordingly, so the value of the module should not be too large or too small.

[0060] Since the reduction ratio is inversely proportional to the number of teeth of the flexible wheel 100, when the module is the same, the more teeth there are, the smaller the diameter of the flexible wheel 100, but the reduction ratio of the entire gear system will increase. Therefore, when optimizing the flexible wheel 100, it is necessary to adjust the relevant parameters of the external teeth 121 according to the different reduction ratios of the harmonic reducer 10. When the reduction ratio of the harmonic reducer increases, the output torque will also increase accordingly. This means that at a high reduction ratio, the harmonic reducer can carry a larger load and is suitable for application scenarios that require high torque output, such as heavy machinery, industrial robots, etc. On the contrary, the output torque of the harmonic reducer at a low reduction ratio is smaller, which is suitable for scenarios with lighter loads or higher speed requirements.

[0061] Specifically, when I < 80:1, it means that the harmonic reducer 10 needs to be suitable for scenes with light loads or high speed requirements. According to the following formulas: Rd1 = df + 0.3*m and Rd2 = df - 0.3*m, the first radius Rd1 and the second radius Rd2 can be determined. Among them, when the reduction ratio I is less than 80:1, it is necessary to reduce speed and increase torque while maintaining a certain output speed. The modulus of the flexible wheel 100 can be 0.2mm, 0.3mm, 0.5mm, etc., and the reduction ratio I can be 30:1, 50:1, 60:1, etc. For example, Figure 3 The flexible wheel 100 shown is an example. The reduction ratio I applied to the harmonic reducer 10 is 50:1, the module m is 0.4 mm, the radius df of the pitch circle is 20 mm, and the first radius Rd1 is calculated to be 20.12 mm according to Rd1=df+0.3*m; the second radius Rd2 is calculated to be 19.88 mm according to Rd2=df-0.3*m. Therefore, the tangent point position of the first arc surface 1211 and the second arc surface 1212 and the tangent point position of the second arc surface 1212 and the third arc surface 1213 can be determined to ensure that the rigid wheel 200 and the flexible wheel 100 can mesh smoothly, improve the transmission efficiency, and meet the high speed requirement of the harmonic reducer 10.

[0062] In other embodiments, when I≥80:1, it means that the harmonic reducer can carry a larger load and is suitable for application scenarios requiring high torque output. The first radius Rd1 and the second radius Rd2 are determined according to the following formulas: Rd1=df+0.454*m and Rd2=df-0.454*m. Among them, when the reduction ratio I of the harmonic reducer 10 is ≥80:1, it can meet a variety of high-precision, high-load, and low-speed application requirements. The modulus of the flexible wheel 100 can be 0.2mm, 0.3mm, 0.5mm, etc., and the reduction ratio I can be 80:1, 100:1, 120:1, etc. For example, Figure 1The flexible wheel 100 shown is an example. The reduction ratio I applied to the harmonic reducer 10 is 80:1, the module m is 0.2 mm, the radius df of the pitch circle is 20 mm, and the first radius Rd1 is calculated to be 20.09 mm according to Rd1=df+0.454*m; the second radius Rd2 is calculated to be 19.91 mm according to Rd2=df-0.454*m. Therefore, the tangent point position of the first arc surface 1211 and the second arc surface 1212 and the tangent point position of the second arc surface 1212 and the third arc surface 1213 can be determined. When the reduction ratio of the harmonic reducer 10 is greater than or equal to 80:1, it is ensured that the rigid wheel 200 and the flexible wheel 100 can mesh smoothly to meet the demand for high torque output.

[0063] Experiments have shown that the second arc surface 1212 is located at the main area where the outer tooth portion 120 and the inner tooth portion 210 mesh, also known as the main meshing area. Optimizing the second arc surface 1212 can further improve the meshing efficiency.

[0064] Reference Figure 1 and Figure 2 As shown, the arc length of the second arc surface 1212 is L2, and the aperture of the inner hole 111 of the flexible wheel 100 is d. When I<80:1, it satisfies: 0.04*d≤L2≤0.052*d, that is, the arc length of the second arc surface 1212 is greater than or equal to 0.04 times the aperture of the inner hole 111, and less than or equal to 0.052 times the aperture of the inner hole 111. The arc length of the second arc surface 1212 is set according to the aperture of the inner hole 111 of the flexible wheel 100. It can be understood that when the reduction ratio I is less than 80:1, it is necessary to reduce speed and increase torque while maintaining a certain output speed. When the modulus of the flexible wheel 100 is the same, the more teeth, the smaller the diameter of the flexible wheel 100, and the smaller the aperture of the inner hole 111 of the flexible wheel 100. Therefore, according to the reduction ratio requirement of the harmonic reducer 10, the number of teeth of the flexible wheel 100 can be determined, thereby determining the size of the inner hole 111 of the flexible wheel 100.

[0065] It should be noted that, since the two ends of the second arc surface 1212 are connected to the first arc surface 1211 and the second arc surface 1212 respectively, the longer the length of the second arc surface 1212 is, the larger the range of the main meshing area is. When L2 is less than 0.04*d, it means that the arc length of the second arc surface 1212 is too small, and the size of the main meshing area is small. Although it has a circular arc surface, it is easily subjected to a large bending stress, and the stress may be more concentrated and aggravated, which is easy to cause fatigue wear and is not conducive to improving the meshing efficiency; when L2 is greater than 0.052*d, it means that the arc length of the second arc surface 1212 is too large, and the size of the main meshing area is large, but it will reduce the arc length of the first arc surface 1211 and the third arc surface 1213. Figure 5 and Figure 6As shown, when the outer tooth portion 120 meshes with the inner tooth portion 210, if the arc length of the first arc surface 1211 and the third arc surface 1213 is too small, the contact surface between the root and top of the outer tooth 121 and the inner tooth 211 will be too small, which is not conducive to forming a stable oil film, and is prone to wear, and the meshing smoothness is also reduced, which does not meet the use requirements when the reduction ratio I is less than 80:1. Therefore, when I < 80:1, under the condition of 0.04*d≤L2≤0.052*d, the requirements for smoother meshing can be met, the meshing efficiency can be improved, and the requirements for better power transmission and deceleration effects can be met.

[0066] Specifically, the value of the diameter d of the inner hole 111 of the flexible wheel 100 can be 40 mm, 50 mm, 60 mm, etc. Figure 3 The flexible wheel 100 shown is an example. The reduction ratio I of the flexible wheel 10 applied to the harmonic reducer 10 is 50:1. When the aperture d of the inner hole 111 of the flexible wheel 100 is 50 mm, the arc length range of the second arc surface 1212 satisfies: 2 mm ≤ L2 ≤ 2.6 mm. This is only an example. The specific size of the arc length of the second arc surface 1212 is selected according to the reduction ratio of the harmonic reducer 10 and the size of the inner hole 111 of the flexible wheel 100.

[0067] In other embodiments, when I≥80:1, 0.138*d≤L2≤0.162*d is satisfied, that is, the arc length of the second arc surface 1212 is greater than or equal to 0.138 times the diameter of the inner hole 111, and less than or equal to 0.162 times the diameter of the inner hole 111. When I≥80:1, it means that the harmonic reducer can carry a larger load and requires an application scenario with high torque output.

[0068] It should be noted that when L2 is less than 0.138*d, it means that the arc length of the second arc surface 1212 is too small, the size of the main meshing area is small, and although it has a circular arc surface, it is susceptible to large bending stress, and the stress may be more concentrated and aggravated, which may easily lead to fatigue wear, which is not conducive to improving the meshing efficiency and does not meet the use requirements when the reduction ratio I is greater than 80:1; when L2 is greater than 0.162*d, it means that the arc length of the second arc surface 1212 is too large, the size of the main meshing area is large, but the arc length of the first arc surface 1211 and the third arc surface 1213 will be reduced. Figure 5 and Figure 6As shown, when the outer tooth portion 120 meshes with the inner tooth portion 210, if the arc length of the first arc surface 1211 and the third arc surface 1213 is too small, the contact surface between the root and top of the outer tooth 121 and the inner tooth 211 will be too small, which is not conducive to forming a stable oil film, and is prone to wear, and the meshing smoothness is also reduced, which does not meet the use requirements when the reduction ratio I is greater than 80:1. Therefore, when the reduction ratio I of the harmonic reducer 10 is ≥80:1, under the above condition of 0.138*d≤L2≤0.162*d, it can meet the requirements of smoother meshing, improve meshing efficiency, and meet the requirements of better power transmission and deceleration effect.

[0069] Specifically, the value of the diameter d of the inner hole 111 of the flexible wheel 100 can be 30 mm, 40 mm, etc. Figure 1 The flexible wheel 100 shown is an example, and the reduction ratio I applied to the harmonic reducer 10 is 80:1. When the aperture d of the inner hole 111 of the flexible wheel 100 is 30 mm, the arc length range of the second arc surface 1212 satisfies: 4.14 mm ≤ L2 ≤ 5.35 mm. This is only an example, and the specific size of the arc length of the second arc surface 1212 is selected according to the reduction ratio of the harmonic reducer 10 and the size of the inner hole 111 of the flexible wheel 100.

[0070] Reference Figure 2 As shown, along the circumference of the flexible wheel 100, the width of the external tooth 121 is t1, and the width of the external tooth 121 is measured at the pitch circle position of the flexible wheel 100. The module of the flexible wheel 100 is m. When the reduction ratio I of the harmonic reducer 10 is less than 80:1, it satisfies: 0.52*Ln(m)+0.86mm≤t1≤0.62*Ln(m)+0.98mm. It can be understood that when optimizing the design of the flexible wheel 100, it is necessary to consider the size parameters of the external tooth 121, especially the relationship between the width t1 of the external tooth 121 at the pitch circle position and the module m. The given inequality relationship is to limit the value range of t1 under the condition that the reduction ratio I is less than 80:1. Among them, the minimum value of t1 is not less than 0.52*Ln(m)+0.86mm. For a given module m, t1 cannot be less than this calculated value. The maximum value of t1 is not greater than 0.62*Ln(m)+0.98mm, and for a given module m, t1 cannot exceed this calculated value. These two limits together define the reasonable width range of the external teeth 121 of the flexible wheel 100 at the pitch circle position under a given reduction ratio. It should be noted that Ln(m) represents a logarithmic function with the natural logarithm as the base, which describes the nonlinear relationship between the module m and the tooth width t1.

[0071] It can be understood that when I<80:1, it means that the harmonic reducer 10 can reduce the input speed at a smaller ratio, thereby outputting a higher speed. This reduction ratio range is suitable for occasions where a higher output speed is required but the torque requirement is not very strict. When t1<0.52*Ln(m)+0.86mm, it means that the width t1 of the outer tooth 121 at the pitch circle position is too small, which reduces the contact area between the outer tooth 121 and the inner tooth 211, resulting in a decrease in meshing performance and a stress concentration problem. The meshing performance and load-bearing capacity cannot meet the use requirements when the reduction ratio I is less than 80:1. When t1>0.62*Ln(m)+0.98mm, it means that the width t1 of the outer tooth 121 at the pitch circle position is too large, resulting in uneven distribution of load in the tooth width direction. The uneven load distribution will increase the range of change of the tooth surface contact stress, thereby accelerating the wear and fatigue damage of the tooth surface and reducing the reliability of the harmonic reducer 10.

[0072] When the specific value of the modulus m is determined, it is substituted into the above formula for calculation to determine the reasonable value range of t1. For example, the value of the modulus of the flexible wheel 100 can be 0.2mm, 0.3mm, 0.5mm, etc. Taking m=0.3 as an example, the width t1 of the outer tooth 121 at the pitch circle position can be calculated according to the above formula to be in the range of: 1.48mm≤t1≤1.72mm. In practical applications, the modulus m is determined according to specific transmission requirements, material properties, load capacity and other factors, and the reasonable value range of t1 is calculated accordingly.

[0073] Reference Figure 8 As shown, after experimental comparison, compared with the traditional harmonic reducer 10, the harmonic reducer 10 of the embodiment of the utility model adopts the flexible wheel 100 of the above embodiment. Since the tooth surface of each external tooth 121 is composed of multiple tangent arc surfaces, and the relevant parameters of the external tooth 121 are optimized, when applied to the harmonic reducer 10, the reduction ratio needs to be less than 80:1, and Rd1=df+0.3*m, Rd2=df-0.3*m, 0.04*d≤L2≤0.052*d and 0.52*Ln(m)+0.86mm≤t1≤0.62*Ln(m)+0.98mm are satisfied. Under the conditions, the meshing of the flexible wheel 100 and the rigid wheel 200 can be smoother, the contact stress can be significantly reduced, the meshing efficiency is higher, the driving speed can be increased by more than 15%, and it is suitable for the scene of high speed output.

[0074] In other embodiments, when the reduction ratio I of the harmonic reducer 10 is ≥80:1, it satisfies: 0.29*Ln(m)+0.68mm≤t1≤0.39*Ln(m)+0.98mm. It can be understood that the given inequality relationship limits the value range of t1 under the condition that the reduction ratio I is greater than or equal to 80:1. Among them, the minimum value of t1 is not less than 0.29*Ln(m)+0.68mm, and for a given module m, t1 cannot be less than this calculated value. The maximum value of t1 is not greater than 0.39*Ln(m)+0.98mm, and for a given module m, t1 cannot exceed this calculated value. These two limits jointly define the reasonable width range of the outer teeth 121 of the flexible wheel 100 at the pitch circle position under a given reduction ratio.

[0075] It is understandable that when the reduction ratio is greater than or equal to 80:1, at a high reduction ratio, the harmonic reducer can carry a larger load and is suitable for application scenarios that require high torque output, such as industrial robots. When t1 < 0.29*Ln(m) + 0.68mm, it means that the width t1 of the outer tooth 121 at the pitch circle position is too small, which reduces the contact area between the outer tooth 121 and the inner tooth 211, resulting in a decrease in meshing performance and a stress concentration problem. The meshing performance and load-bearing capacity cannot meet the use requirements when the reduction ratio I is greater than or equal to 80:1. When t1 > 0.39*Ln(m) + 0.98mm, it means that the width t1 of the outer tooth 121 at the pitch circle position is too large, resulting in uneven distribution of the load in the tooth width direction. The uneven load distribution will increase the range of change of the tooth surface contact stress, thereby accelerating the wear and fatigue damage of the tooth surface and reducing the reliability of the harmonic reducer 10.

[0076] Reference Fig. 9 As shown, after experimental comparison, compared with the traditional harmonic reducer 10, the harmonic reducer 10 of the embodiment of the utility model adopts the flexible wheel 100 of the above embodiment. Since the tooth surface of each external tooth 121 is composed of multiple tangent arc surfaces, and the relevant parameters of the external tooth 121 are optimized, when the harmonic reducer 10 is applied to the reduction ratio greater than or equal to 80:1, and satisfies Rd1=df+0.454*m, Rd2=df-0.454*m, 0.138*d≤L2≤0.162*d and 0.29*Ln(m)+0.68mm≤t1≤0.39*Ln(m)+0.98mm, the meshing of the flexible wheel 100 and the rigid wheel 200 can be smoother, the load capacity is higher, and the transmission efficiency can be improved by more than 10%, which is suitable for occasions requiring high torque, high precision and low speed.

[0077] Reference Figure 5As shown, the embodiment of the utility model further provides a harmonic reducer 10, which is suitable for industrial robots, automation devices and other equipment. The harmonic reducer 10 includes a rigid wheel 200, a flexible wheel 100 and a wave generator 300, wherein the flexible wheel 100 adopts the flexible wheel 100 structure of the above embodiment, the flexible wheel 100 is installed on the inner side of the rigid wheel 200, and the wave generator 300 is installed in the inner hole 111 of the flexible wheel 100, and the wave generator 300 is configured to make the outer tooth portion 120 mesh with the inner tooth portion 210 when rotating.

[0078] Reference Figure 5 As shown, the wave generator 300 includes a flexible bearing 310 and a cam 320. The flexible bearing 310 is sleeved on the cam 320. The flexible bearing 310 is a thin-walled bearing that can be elastically deformed. The cam 320 is used to connect a driving device such as a motor. Taking the motor as an example, when the motor drives the cam 320 to rotate, the flexible bearing 310 is deformed regularly with the rotation of the cam 320, thereby forcing the flexible wheel 100 to deform repeatedly, thereby driving the flexible wheel 100 to rotate at a low speed in the opposite direction of the wave generator 300 relative to the rigid wheel 200.

[0079] Reference Figure 7 As shown, in the embodiment of the utility model, the flexible wheel 100 also includes a connecting portion 130, the outer tooth portion 120 is arranged on the outer peripheral wall at one end of the cylinder 110, the connecting portion 130 is arranged at the other end of the cylinder 110, the wave generator 300 is installed in the cylinder 110, and the connecting portion 130 is used to connect the output component.

[0080] During the operation of the harmonic reducer 10, the wave generator 300 forces the flexible wheel 100 to produce elastic deformation and become elliptical when in operation. The flexible wheel 100 is completely meshed with the rigid wheel 200 in the major axis direction of the ellipse and completely separated in the minor axis direction. The remaining teeth are either in the meshing state or in the meshing state depending on the rotation position of the flexible wheel 100. Figure 6 Schematic diagram of the meshing state of the outer teeth 121 and the inner teeth 211 is shown in FIG. As the wave generator 300 rotates continuously, the meshing state of the flex spline 100 and the rigid spline 200 will continuously change, thereby achieving relative deceleration motion between the flex spline 100 and the rigid spline 200.

[0081] It is understandable that the flexible wheel 100 is generally used as the output component of the harmonic reducer 10. Through the rotation of the flexible wheel 100, the harmonic gear device can convert the input motion of the wave generator 300 into the output motion of the flexible wheel 100, thereby realizing power transmission and reduction.

[0082] As shown in reference 7, the harmonic reducer 10 also includes an output assembly, which is connected to the connecting portion 130 of the flexible wheel 100. Specifically, one end of the cylinder 110 away from the outer tooth portion 120 is bent toward the outside to form the connecting portion 130, and the connecting portion 130 is roughly disc-shaped. The connecting portion 130 is provided with a flange portion 140, and the flange portion 140 is provided with a plurality of mounting holes, and the plurality of mounting holes are arranged along the circumference of the flange portion 140. The flange portion 140 passes through the mounting holes and is connected to the output assembly through fasteners such as bolts, so as to realize the transmission of power from the flexible wheel 100 to the output component. The output assembly is used to connect other devices to transmit motion and torque to other devices. For example, the output assembly is connected to the mechanical arm of an industrial robot, so as to drive the mechanical arm to move to perform corresponding operations.

[0083] In some embodiments, the output assembly may be a bearing structure, wherein the fixed portion is the outer ring of the bearing structure and the rotating portion is the inner ring of the bearing structure. Of course, the specific form of the output assembly may be selected according to the requirements of the actual application.

[0084] The present utility model also provides an industrial robot, comprising the harmonic reducer 10 shown in the above embodiment. Figures 1 to 7 As shown, in the embodiment of the utility model, since the tooth surface of the external teeth 121 is composed of a plurality of arc surfaces, and the tooth surfaces between adjacent external teeth 121 are also connected by arc surfaces, the arc surfaces are beneficial to reducing friction, and can make the external tooth portion 120 of the flexible wheel 100 and the internal tooth portion 210 of the rigid wheel 200 mesh more smoothly, the friction torque is lower under the same torsional stiffness, and the meshing efficiency is higher, thereby improving the transmission efficiency, which is beneficial to improving the output performance of the harmonic reducer 10.

[0085] The industrial robot in the embodiment of the utility model can specifically be an automated device including a robotic arm. A motor and a harmonic reducer 10 for driving the movement of the robotic arm can be provided at each joint of the robotic arm. The harmonic reducer 10 is connected to the motor, and the motor drives the harmonic reducer 10 to transmit and reduce power, thereby driving the movement of the robotic arm.

[0086] Since the industrial robot includes the harmonic reducer 10 of the above embodiment, it at least has the beneficial effects of the above harmonic reducer 10, which will not be described in detail here.

[0087] Of course, the present invention is not limited to the above-mentioned embodiments, and technicians familiar with the field may make equivalent modifications or substitutions without violating the spirit of the present invention. These equivalent modifications or substitutions are all included in the scope defined by the claims of this application.

Claims

1. A flexible wheel, applied to a harmonic reducer, characterized in that: include: The cylinder is provided with an external tooth portion, which includes a plurality of external teeth arranged at intervals along the outer peripheral wall of the cylinder, wherein the end of each external tooth connected to the cylinder is a root, and the end away from the root is a top, and the tooth surface of the external tooth includes a first arc surface, a second arc surface and a third arc surface connected in sequence from the top to the root, the first arc surface is tangent to the second arc surface, and the second arc surface is tangent to the third arc surface.

2. The flexible wheel according to claim 1, characterized in that: The first arc surface, the second arc surface and the third arc surface are arc surfaces respectively.

3. The flexible wheel according to claim 1, characterized in that: The reduction ratio of the harmonic reducer is I, the center of the cylinder is the center of the circle, the distance between the tangent point of the first arc surface and the second arc surface and the center of the circle is the first radius, the first radius is Rd1, the pitch circle radius of the flexible wheel is df, the module of the flexible wheel is m, and it satisfies: when I<80:1, Rd1=df+0.3*m.

4. The flexible wheel according to claim 1 or 3, characterized in that: The reduction ratio of the harmonic reducer is I, the center of the cylinder is the center of the circle, the distance between the tangent point of the second arc surface and the third arc surface and the center of the circle is the second radius, the second radius is Rd2, the pitch circle radius of the flexible wheel is df, the module of the flexible wheel is m, and it satisfies: when I<80:1, Rd2=df-0.3*m.

5. The flexible wheel according to claim 1, characterized in that: The reduction ratio of the harmonic reducer is I, the center of the cylinder is the center of the circle, the distance between the tangent point of the first arc surface and the second arc surface and the center of the circle is the first radius, the first radius is Rd1, the pitch circle radius of the flexible wheel is df, the module of the flexible wheel is m, and it satisfies: when I≥80:1, Rd1=df+0.454*m.

6. The flexible wheel according to claim 1 or 5, characterized in that: The reduction ratio of the harmonic reducer is I, the center of the cylinder is the center of the circle, the distance between the tangent point of the second arc surface and the third arc surface and the center of the circle is the second radius, the second radius is Rd2, the pitch circle radius of the flexible wheel is df, the module of the flexible wheel is m, and it satisfies: when I≥80:1, Rd2=df-0.454*m.

7. The flexible wheel according to claim 1, characterized in that: The reduction ratio of the harmonic reducer is I, the arc length of the second arc surface is L2, and the aperture of the inner hole of the flexible wheel is d, which satisfies: when I<80:1, 0.04*d≤L2≤0.052*d.

8. The flexible wheel according to claim 1 or 7, characterized in that: The reduction ratio of the harmonic reducer is I, the arc length of the second arc surface is L2, and the aperture of the inner hole of the flexible wheel is d, which satisfies: when I≥80:1, 0.138*d≤L2≤0.162*d.

9. The flexible wheel according to claim 1, characterized in that: The flexible wheel is applied to a harmonic reducer, the reduction ratio of the harmonic reducer is I, along the circumference of the flexible wheel, the width of the external tooth at the pitch circle position of the flexible wheel is t1, the module of the flexible wheel is m, and it satisfies: when I<80:1, 0.52*Ln(m)+0.86mm≤t1≤0.62*Ln(m)+0.98mm.

10. The flexible wheel according to claim 1 or 9, characterized in that: The flexible wheel is applied to a harmonic reducer, the reduction ratio of the harmonic reducer is I, along the circumference of the flexible wheel, the width of the external tooth at the pitch circle position of the flexible wheel is t1, the module of the flexible wheel is m, and it satisfies: when I≥80:1, 0.29*Ln(m)+0.68mm≤t1≤0.39*Ln(m)+0.98mm.

11. A harmonic reducer, characterized in that: include: A rigid wheel having an internal tooth portion; The flexible spline according to any one of claims 1 to 10, wherein the flexible spline is mounted in the inner hole of the rigid spline; A wave generator is installed on the inner side of the flexible wheel, and the wave generator is configured to make the outer tooth portion mesh with the inner tooth portion when rotating.

12. An industrial robot, characterized in that: Including the harmonic reducer as described in claim 11.

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