Oil seal structure, harmonic speed reducer and robot

Abstract

The invention discloses an oil seal structure, a harmonic speed reducer and a robot, and relates to the technical field of sealing. The framework is embedded in the elastic sealing ring, and the inner wall of the elastic sealing ring is provided with a main sealing lip and a dustproof lip which are arranged at an interval; the air side face of the main sealing lip is provided with a plurality of sets of two-way oil return structures distributed at intervals in the circumferential direction, and each two-way oil return structure comprises a plurality of parallel first oil return lines and a plurality of parallel second oil return lines. The first oil return line and the second oil return line obliquely extend relative to the axial direction of the elastic sealing ring, the inclination directions of the first oil return line and the second oil return line are opposite, the first oil return line and the second oil return line are arranged in a spaced mode, and the height H, protruding out of the main sealing lip, of the first oil return line and / or the second oil return line is larger than or equal to 0.02 mm and smaller than or equal to 0.04 mm. According to the technical scheme, the sealing effect is improved.

Description

Technical Field

[0001] This invention relates to the field of sealing technology, and in particular to an oil seal structure, a harmonic reducer, and a robot. Background Technology

[0002] Harmonic reducers are widely used in robot joint drive systems due to their advantages such as high reduction ratio, compact structure, and high transmission accuracy. A harmonic reducer mainly consists of three core components: a flexible wheel, a rigid wheel, and a wave generator. These components typically require high-performance grease filling to ensure smooth transmission between components, reduce wear, and extend service life. To prevent grease leakage during operation due to centrifugal force, temperature rise, or vibration, an oil seal structure is installed on the crossed roller bearings to achieve a seal, thereby preventing grease leakage.

[0003] In actual operation, conventional oil seal structures with only smooth sealing lips cannot adapt to the frequent start-stop, reversal, and ultra-low speed operation of robot joints, making it difficult to form a sealing oil film, which in turn causes grease leakage. Summary of the Invention

[0004] The main objective of this invention is to provide an oil seal structure, a harmonic reducer, and a robot, in order to solve the aforementioned technical problems.

[0005] To achieve the above objectives, embodiments of the present invention provide an oil seal structure, the oil seal structure comprising:

[0006] skeleton; An elastic sealing ring, wherein the skeleton is embedded in the elastic sealing ring, and the inner wall of the elastic sealing ring has a main sealing lip and a dustproof lip spaced apart; wherein, The air side of the main sealing lip is provided with multiple sets of bidirectional oil return structures distributed circumferentially. The bidirectional oil return structure includes multiple parallel first oil return lines and multiple parallel second oil return lines. The first oil return lines and the second oil return lines extend obliquely relative to the axial direction of the elastic sealing ring and in opposite directions. The first oil return lines and the second oil return lines are spaced apart. The height H of the first oil return line and / or the second oil return line protruding from the main sealing lip is 0.02 mm ≤ H ≤ 0.04 mm.

[0007] In one embodiment, the first return oil line and the second return oil line are symmetrically arranged along the axial direction; and / or, the first return oil line and the second return oil line have the same height; and / or, the number of the first return oil line and the number of the second return oil line are the same.

[0008] In one embodiment, at least one of the first return oil line and the second return oil line has a cross-section having two opposing first planes and a first arc surface connecting the two first planes; The radius of the circle containing the first arc surface is R1, 0.04 mm ≤ R1 ≤ 0.06 mm; and / or, the included angle between the two first planes is α, 117 degrees ≤ α ≤ 123 degrees.

[0009] In one embodiment, in each group of the bidirectional oil return structures, the number of the first oil return lines and / or the number of the second oil return lines is 10 to 11, and / or the interval between two adjacent first oil return lines and the interval between two adjacent second oil return lines is d, 0.45 mm ≤ d ≤ 0.5 mm.

[0010] In one embodiment, the main sealing lip has an oil side and an air side, the oil side and the air side intersecting at a first intersection line, and at least one of the first return oil line and the second return oil line makes an angle β with the first intersection line, where 19 degrees ≤ β ≤ 21 degrees.

[0011] In one embodiment, the extension length of at least one of the first return oil line and the second return oil line is L1, where 6 mm ≤ L1 ≤ 8 mm.

[0012] In one embodiment, the bidirectional oil return structure satisfies the following functional relationship: C1 = (1.2~1.5) d / sinβ, and C1≥1 mm; Wherein, C1 is the distance between the first and second oil return lines in two adjacent sets of bidirectional oil return structures at the end furthest from the dustproof lip.

[0013] In one embodiment, the dustproof lip has a plurality of bidirectional airflow guiding structures distributed circumferentially on one side wall facing the main sealing lip, which are used to form an airflow pointing towards the external environment.

[0014] In one embodiment, the bidirectional flow-guiding structure includes a first flow-guiding protrusion and a second flow-guiding protrusion. The first flow-guiding protrusion and the second flow-guiding protrusion are protruding on the side of the dustproof lip facing the main sealing lip and are spaced apart along the circumference of the dustproof lip. The first flow-guiding protrusion and the second flow-guiding protrusion are both inclined relative to the axial direction of the elastic sealing ring and the inclination directions are opposite. The height of at least one of the first and second guide protrusions protruding from the dustproof lip is h, where 0.07 mm ≤ h ≤ 0.09 mm.

[0015] In one embodiment, at least one of the first and second guide protrusions has a cross-section with two opposing second planes and a second arc surface connecting the two second planes; The radius of the circle containing the second arc surface is R2, 0.09 mm ≤ R2 ≤ 0.11 mm; and / or, the included angle between the two second planes is γ, 132 degrees ≤ γ ≤ 138 degrees.

[0016] In one embodiment, the main sealing lip and the dustproof lip intersect at a second intersection line, and at least one of the first guide protrusion and the second guide protrusion makes an angle θ with the second intersection line, where 56 degrees ≤ θ ≤ 62 degrees; and / or, The extension length of at least one of the first guide protrusion and the second guide protrusion is L2, where 1 mm ≤ L2 ≤ 1.5 mm.

[0017] In one embodiment, the inner wall surface of the elastic sealing ring is provided with a friction-reducing coating.

[0018] To achieve the above objectives, this invention provides a harmonic reducer, which includes a flexible wheel, a bearing, a rigid wheel, and the aforementioned oil seal structure. The flexible wheel and the rigid wheel are rotatably connected. The bearing is located between the flexible wheel and the rigid wheel and has a mounting groove. The oil seal structure is located in the mounting groove. The linear velocity at the output end of the harmonic reducer is less than or equal to 1 m / s or the rotational speed is less than or equal to 100 r / min.

[0019] To achieve the above objectives, embodiments of the present invention provide a robot, the robot comprising a robot body and a harmonic reducer connected to the robot body, wherein the harmonic reducer is the harmonic reducer described above.

[0020] The technical solution of this application integrates a double-lip structure of a main sealing lip and a dustproof lip on the inner wall of the elastic sealing ring. This not only effectively prevents external dust and impurities from entering the reducer, but also forms a reliable first sealing barrier for the lubricating grease, reducing the risk of leakage. Secondly, a first and second oil return line with opposite inclinations are set on the air side of the main sealing lip, forming multiple sets of bidirectional oil return structures spaced circumferentially. Regardless of whether the rotation is forward or reverse, the corresponding oil return line can generate a pumping effect, guiding the trace amount of leaked lubricating grease back along the inclined oil return line, reducing the risk of lubricating grease leakage. The height of the oil return line protruding from the main sealing lip is between 0.02 mm and 0.04 mm, which helps reduce the contact pressure between the oil seal lip and the shaft, slows down the wear of the oil seal, ensures oil return capability, and contributes to the continuous formation of the oil film, ensuring oil return efficiency while forming a continuous oil film. Simultaneously, the skeleton embedded in the elastic sealing ring provides support for the entire oil seal structure, maintaining stable sealing contact pressure and geometry. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0022] Figure 1 This is an exploded structural diagram of an embodiment of the harmonic reducer of the present invention; Figure 2 This is a cross-sectional structural schematic diagram of an embodiment of the harmonic reducer of the present invention; Figure 3 This is a cross-sectional structural schematic diagram of an embodiment of the oil seal structure of the present invention; Figure 4 This is another cross-sectional structural schematic diagram of an embodiment of the oil seal structure of the present invention; Figure 5 for Figure 4 Schematic diagram of the cross-sectional structure of the middle AA section; Figure 6 for Figure 4 Schematic diagram of the cross-sectional structure of the middle BB section; Figure 7 This is a schematic diagram of an embodiment of the oil seal structure of the present invention; Figure 8 This is another cross-sectional structural schematic diagram of an embodiment of the oil seal structure of the present invention; Explanation of icon numbers: 100. Oil seal structure; 110. Skeleton; 120. Elastic sealing ring; 121. Main sealing lip; 122. Dustproof lip; 123. Clamping element; 130. Bidirectional oil return structure; 131. First oil return line; 1311. First plane; 1312. First arc surface; 132. Second oil return line; 140. Bidirectional flow guidance structure; 141. First flow guidance protrusion; 1411. Second plane; 1412. Second arc surface; 142. Second flow guidance protrusion; 151. First intersection line; 152. Second intersection line; 200, flexible wheel; 300, bearing; 400, rigid wheel.

[0023] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the embodiments of the present invention.

[0025] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0026] Furthermore, in the embodiments of this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of the embodiments of this invention, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0027] In the embodiments of the present invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present invention according to the specific circumstances.

[0028] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the protection scope required by the embodiments of the present invention.

[0029] Harmonic reducers mainly consist of three core components: a flexible wheel, a rigid wheel, and a wave generator. They typically require internal high-performance grease to ensure smooth transmission between components, reduce wear, and extend service life. To prevent grease leakage during operation due to centrifugal force, temperature rise, or vibration, an oil seal structure is installed on the crossed roller bearings to achieve a seal and prevent grease leakage. However, in actual operation, especially under conditions of frequent start-stop, reversal, and ultra-low speed operation of robot joints, it is difficult to form a sealing oil film, leading to grease leakage. It is understandable that the following conditions are considered acceptable: linear velocity at the output end not exceeding 1 m / s, rotational speed not exceeding 100 r / min, frequent start-stop, or joint acceleration not exceeding 3000° / s². 2 In situations involving frequent forward and reverse rotation, the oil seal structure is not prone to forming a sealing oil film, which can easily lead to leakage.

[0030] In view of this, embodiments of the present invention provide an oil seal structure that is suitable for operating conditions where the linear velocity at the output end is not higher than 1 m / s, or the rotational speed is not higher than 100 r / min, or there are frequent starts and stops, or the joint acceleration is not higher than 3000 ° / s², or there are frequent forward and reverse rotations. The oil return line on the air side of the main sealing lip protrudes from the main sealing lip by a height between 0.02 mm and 0.04 mm, which helps reduce the contact pressure between the oil seal lip and the shaft, slows down the wear of the oil seal, ensures oil return capability, and facilitates the continuous formation of the oil film, thus ensuring oil return efficiency while forming a continuous oil film. In addition, the inner wall of the dustproof lip is provided with a bidirectional airflow structure, which forms a directional airflow pointing outwards during operation, effectively "blowing" dust and moisture away from the sealing area, forming an air barrier protective layer, further enhancing the overall dustproof and sealing performance.

[0031] To better understand the above technical solution, the following detailed explanation is provided in conjunction with the accompanying drawings.

[0032] like Figure 3 and Figure 4 As shown, an embodiment of the present invention proposes an oil seal structure, wherein the oil seal structure 100 includes: The frame 110 provides support and can be made of metal materials such as stainless steel and cold-rolled steel. The elastic sealing ring 120 is fitted with the skeleton 110. The inner wall of the elastic sealing ring 120 has a main sealing lip 121 and a dustproof lip 122 spaced apart. Specifically, the elastic sealing ring 120, as the sealing body, can be made of rubber or plastic material. Optionally, the elastic sealing ring 120 is a circular ring. The main sealing lip 121 is mainly used to prevent grease leakage, and the dustproof lip 122 is mainly used to prevent dust, moisture, etc. from entering. Furthermore, the elastic sealing ring 120 is fitted with a clamping member 123, which can clamp the elastic sealing ring 120 onto the inner ring of the bearing 300 or the shaft. Specifically, the clamping member 123 can be a spring or a spring sheet, etc., which is not limited here. A bidirectional oil return structure 130 is provided on the air side of the main sealing lip 121 and is distributed in multiple sets at intervals along the circumference. Each set of the bidirectional oil return structure 130 may include multiple parallel first oil return lines 131 and multiple parallel second oil return lines 132. The first oil return lines 131 and the second oil return lines 132 are distributed in a figure-eight shape along the axial direction and are spaced apart. It can be understood that the first oil return lines 131 and the second oil return lines 132 are both inclined relative to the axial direction of the elastic sealing ring 120, and the inclination directions of the first oil return lines 131 and the second oil return lines 132 are opposite to form a figure-eight oil return line.

[0033] In this embodiment, the first return oil line 131 and the second return oil line 132 can be arranged symmetrically or asymmetrically along the axial direction. The heights of the first return oil line 131 and the second return oil line 132 can be the same or different. The number of the first return oil line 131 and the second return oil line 132 in each group can be the same or different. The specific number can be determined according to the actual situation. This embodiment of the specification does not limit this.

[0034] The height H of the first return oil line 131 and / or the second return oil line 132 protruding from the main sealing lip 121 is 0.02 mm ≤ H ≤ 0.04 mm, preferably 0.03 mm. When the height of the return oil line is greater than 0.04 mm, the pumping capacity will decrease, and the grease cannot be effectively guided to the return oil side. Leakage is likely to occur after more than 24 hours of operation under conditions such as an output linear velocity not exceeding 1 m / s, a rotational speed not exceeding 100 r / min, frequent start-stop, joint acceleration not exceeding 3000 ° / s², or frequent forward and reverse rotation. Conversely, when the height of the return oil line is less than 0.02 mm, the pumping action is too strong, the return oil rate is too fast, and the necessary lubricating oil film will also be guided to the return oil side, resulting in insufficient lubricating oil film between the lip and the shaft. This easily causes dry friction, reduces chip-holding capacity, and makes it easy to be clogged by impurities, adversely affecting the sealing performance and reducing the sealing effect.

[0035] Therefore, in this embodiment, the height of the first oil return line 131 and / or the second oil return line 132 protruding from the main sealing lip 121 is preferably between 0.02 mm and 0.04 mm. While ensuring oil return efficiency, a continuous oil film will be formed. The protrusion height of the oil return line can be 0.02 mm, 0.025 mm, 0.027 mm, 0.03 mm, 0.35 mm, 0.38 mm, 0.04 mm, etc., and can be determined according to the actual situation. This embodiment does not limit this.

[0036] It should be noted that the protrusion height of the return oil line referred to in this embodiment can be the maximum height protruding from the main sealing lip 121. During measurement, the radial protrusion height can be measured using the surface of the main sealing lip 121 where no elastic deformation has occurred as the measurement reference. In some embodiments, due to process reasons, the top of the return oil line cross-section may be arc-shaped or other irregularly shaped. In this case, the protrusion height of the return oil line can also be the normal distance between the intersection point of the tangents on both sides of the return oil line cross-section and the surface of the main sealing lip 121 where no elastic deformation has occurred. Figure 5 H is shown in the diagram.

[0037] There are generally two methods for measuring the protrusion height of the return oil line. One method requires disrupting the overall structure, i.e., cutting the part to be measured and then measuring the height at the corresponding position on the cut surface. The other method is to use optical projection, laser interferometry, or other methods to perform three-dimensional imaging, and then calculate the height at the corresponding position based on the three-dimensional image through simulation modeling. Of course, other possible methods can also be used to measure the height. In actual measurement, the optimal method can be selected, and this embodiment does not limit the method.

[0038] In this embodiment, the first oil return line 131 and the second oil return line 132 can be designed with equal width and height along their respective extension directions. That is, the width and height of the first oil return line 131 are the same at different positions, and the width and height of the second oil return line 132 are the same at different positions. This allows them to be evenly distributed throughout the inner circumference of the elastic sealing ring 120, thus improving the oil return effect. It is understood that due to factors such as manufacturing processes, the first oil return line 131 and the second oil return line 132 cannot achieve absolutely equal width and height in actual products; there will be certain design tolerances. Furthermore, the first oil return line 131 and the second oil return line 132 can also be designed with other possible shapes, which can be determined according to the actual situation. This embodiment does not limit this.

[0039] In this embodiment, the cross-sections of the first return oil line 131 and the second return oil line 132 can be isosceles triangles, semicircles, trapezoids, or racetrack shapes, etc. The specific shape can be determined according to the actual situation, and this embodiment does not limit it.

[0040] In this embodiment, the inner wall of the elastic sealing ring 120 integrates a double-lip structure of the main sealing lip 121 and the dustproof lip 122. This not only effectively prevents external dust and impurities from entering the reducer, but also forms a reliable first sealing barrier for the lubricating grease, reducing the risk of leakage. Secondly, a first oil return line 131 and a second oil return line 132 with opposite inclinations are provided on the air side of the main sealing lip 121, forming a figure-eight-shaped oil return line. This constitutes a bidirectional oil return structure 130 with multiple sets spaced circumferentially. Regardless of whether the rotation is forward or reverse, the corresponding oil return line can generate a pumping effect, guiding the trace amounts of leaked lubricating grease back along the inclined oil return line, reducing the risk of lubricating grease leakage. The height of the oil return line protruding from the main sealing lip 121 is between 0.02 mm and 0.04 mm, which helps reduce the contact pressure between the oil seal lip and the shaft, slows down the wear of the oil seal, ensures oil return capability, and contributes to the continuous formation of the oil film. This ensures oil return efficiency while forming a continuous oil film.

[0041] In one embodiment of the present invention, the first oil return line 131 and the second oil return line 132 can be symmetrically arranged along the axial direction. The symmetrical arrangement makes the return path length and resistance of the lubricating oil basically the same, effectively avoiding the problem of insufficient local lubrication or oil accumulation caused by uneven oil return, thereby improving the stability and reliability of the overall lubrication system. Moreover, symmetrical structures usually have good manufacturability, simplifying the processing flow and reducing production costs.

[0042] In other embodiments, the first return oil line 131 and the second return oil line 132 may have the same height. A uniform height improves the surface regularity of the overall structure, makes the overall structure more compact, and reduces the complexity of design and manufacturing.

[0043] In other embodiments, the number of the first oil return lines 131 and the number of the second oil return lines 132 can be the same, thereby improving the uniformity of the seal and reducing wear.

[0044] In one embodiment of the present invention, reference is made to... Figure 5 At least one of the first return oil line 131 and the second return oil line 132 has a cross-section with two opposing first planes 1311 and a first arc surface 1312 connecting the two first planes 1311. Thus, the two first planes 1311 provide stable flow guiding boundaries, effectively limiting the lateral diffusion of the grease, while the first arc surface 1312 reduces flow resistance and avoids stress concentration, thereby improving return oil efficiency and stress uniformity. It is understood that the first return oil line 131 has a first plane 1311 and a first arc surface 1312, or the second return oil line 132 has a first plane 1311 and a first arc surface 1312, or the first return oil line 131 and the second return oil line 132 each have a first plane 1311 and a first arc surface 1312; this is not limited here.

[0045] Reference Figure 5 The radius of the circumference where the first arc surface 1312 is located is R1, where 0.04 mm ≤ R1 ≤ 0.06 mm. In this way, while ensuring the overall protrusion height of the return oil line, limiting the radius of the circumference where the first arc surface 1312 is located can provide a smooth and continuous transition path for the return of grease, reducing flow resistance and local turbulence.

[0046] Reference Figure 5 In another embodiment, the included angle between the two first planes 1311 is α, where 117 degrees ≤ α ≤ 123 degrees. By limiting the included angle between the two first planes 1311, sufficient lateral restraint force can be maintained to prevent grease diffusion and improve the oil return effect.

[0047] Understandably, by limiting the above parameters such as circumference radius and included angle, a good balance is achieved between sealing performance, oil return efficiency and durability, thereby improving the long-term sealing reliability and stability of the oil seal structure 100 under operating conditions such as low speed, frequent turning and frequent start and stop of the harmonic reducer.

[0048] In one embodiment of the present invention, in each group of bidirectional oil return structures 130, the number of first oil return lines 131 can be 10 to 11. Similarly, the number of second oil return lines 132 can also be 10 to 11. Furthermore, the number of first oil return lines 131 and second oil return lines 132 are each 10 to 11. In this way, while ensuring a sealing effect, the oil return capacity can be improved.

[0049] In one embodiment of the present invention, reference is made to... Figure 4 The interval between two adjacent first return oil lines 131 and the interval between two adjacent second return oil lines 132 are both d, where 0.45 mm ≤ d ≤ 0.5 mm. In other words, the interval between two adjacent first return oil lines 131 can be d, or the interval between two adjacent second return oil lines 132 can be d. Specifically, the conventional number of return oil lines is 1-5. If the distance between two adjacent return oil lines is greater than 1 mm, the return oil efficiency is poor.

[0050] Therefore, in this embodiment, by reducing the spacing between two adjacent return oil lines and increasing the number of return oil lines, the pumping capacity and return oil efficiency can be improved, thereby enhancing the return oil capacity. It should be noted that while increasing the number of return oil lines improves the return oil capacity, a larger number of return oil lines increases the friction between the oil seal structure 100 and the inner ring of the crossed rollers, accelerating wear, reducing contact pressure, and adversely affecting the sealing effect. Therefore, in this embodiment, the number of return oil lines is set to 10 or 11. By coordinating the height design of the first return oil line 131 and the second return oil line 132 with a small spacing, the pumping effect can be better achieved under low-speed conditions while ensuring the sealing effect, thereby improving the return oil capacity. In this embodiment, the interval d can be 0.45 mm, 0.47 mm, 0.48 mm, 0.5 mm, etc., and is not limited here.

[0051] It should be noted that the spacing between two adjacent first return oil lines 131 and the spacing between two adjacent second return oil lines 132 can be the same or different. The optimal setting can be selected according to the actual use situation, and this embodiment does not limit it.

[0052] In one embodiment of the present invention, reference is made to... Figure 4 The main sealing lip 121 has an oil side and an air side, which intersect at a first intersection line 151. At least one of the first oil return line 131 and the second oil return line 132 forms an angle β with the first intersection line 151, where 19 degrees ≤ β ≤ 21 degrees. It can be understood that the angle β between the first oil return line 131 and the first intersection line 151 can also be the angle β between the second oil return line 131 and the first intersection line 151, or both the angles between the first oil return line 131 and the first intersection line 151 and the second oil return line 132 and the first intersection line 151 can be β. Thus, 4 to 8 sets of bidirectional oil return structures 130 can be set, providing more oil return lines while ensuring a good sealing effect, thereby improving the oil return capacity. Optionally, the value of the angle β can be 19 degrees, 20 degrees, 21 degrees, etc., and is not limited here.

[0053] In one embodiment of the present invention, reference is made to... Figure 4The extension length of at least one of the first oil return line 131 and the second oil return line 132 is L1, where 6 mm ≤ L1 ≤ 8 mm. It can be understood that the extension length of either the first oil return line 131 or the second oil return line 132 can be L1. This maximizes the length of either the first oil return line 131 or the second oil return line 132. Compared to the conventional method of processing oil return lines only at the front end of the air-side lip of the main sealing lip 121, extending the first oil return line 131 or the second oil return line through the entire air side of the main sealing lip 121 improves oil return capacity and sealing performance. Optionally, the extension length L1 can be 6 mm, 6.5 mm, 7 mm, 7.5 mm, 8 mm, etc., and is not limited here. Specifically, the extension length refers to the straight-line distance between the first end near the dustproof lip 122 and the second end near the first intersecting line 151.

[0054] It should be noted that the structure of the second return oil line 132 is the same as that of the first return oil line 131.

[0055] In one embodiment of the present invention, further reference is made to Figure 7 and Figure 8 The bidirectional oil return structure satisfies the following functional relationship: C1 = (1.2~1.5) d / sinβ, and C1≥1 mm; Wherein, C1 is the distance between the first and second oil return lines in two adjacent sets of bidirectional oil return structures at the end furthest from the dustproof lip.

[0056] In practical applications, the smaller the spacing of C1, the better the sealing effect; the larger the spacing of C1, the less prone to wear. It is understandable that a smaller spacing of C1 results in a better sealing effect but is more susceptible to wear; a larger spacing of C1 reduces wear but compromises the sealing effect, making oil leakage more likely. Therefore, this embodiment, by limiting the spacing of C1, can reduce wear while ensuring a good sealing effect.

[0057] Furthermore, 2πR≈N (2) M d / sinβ+2 A / tanβ+C1+C2).

[0058] Wherein, R is the radius of the main sealing lip, C1 is the distance between the ends of the first and second oil return lines away from the dustproof lip in two adjacent sets of bidirectional oil return structures, C2 is the distance between the ends of the first and second oil return lines near the dustproof lip in the same set of bidirectional oil return structures, A is the vertical distance from the end of the first oil return line 131 or the second oil return line 132 away from the first intersection line to the first intersection line, M is the number of the first oil return lines in each set of bidirectional oil return structures, and N is the number of sets of bidirectional oil return structures.

[0059] This ensures that the oil line can effectively guide leaked oil back to the oil chamber, and the multiple sets of oil return structures are evenly distributed on the circumference, without overlapping or interfering with each other. Specifically, given R, the maximum allowable number of sets or other parameters can be calculated to meet manufacturing and sealing performance requirements within space constraints.

[0060] In this embodiment, the right side of the above relationship represents the sum of multiple line segments in N groups, and the left side represents the circumference of a circle. The sum of all the line segments represented on the right side is approximately equal to the circumference of a circle, but not exactly equal.

[0061] In one embodiment, with the shaft diameter of the oil seal being 68 mm, the seat hole diameter of the oil seal being 78 mm, and the oil sealing height being 5 mm, the oil seal structure proposed in this embodiment operates with the following parameters: height H=0.03 mm, d=0.5 mm, L1=6.5 mm, β=20 degrees of the first and second oil return lines, and a maximum speed of 0.344 m / s under forward and reverse rotation conditions, without leakage for 5264.5 hours.

[0062] In another embodiment, with the shaft diameter of the oil seal being 68 mm, the seat hole diameter of the oil seal being 78 mm, and the oil sealing height being 5 mm, the oil seal structure proposed in this embodiment operates under forward and reverse conditions with the heights of the first and second oil return lines H=0.03 mm, d=0.45 mm, L1=7.5 mm, and β=21 degrees, and without leakage after 5301 hours of operation at a maximum speed of 0.504 m / s.

[0063] In one embodiment of the present invention, reference is made to... Figure 3 and Figure 4 The dustproof lip has multiple sets of bidirectional airflow guiding structures distributed circumferentially on one side wall facing the main sealing lip, used to form airflow directed towards the external environment. It can be understood that the bidirectional airflow guiding structure 140 is used to guide the airflow; that is, whether rotating clockwise or counterclockwise, it can form an outward-flowing airflow, thereby blowing dust, moisture, etc., away from the sealing area. Optionally, the bidirectional airflow guiding structure 140 can be guide ribs with different inclination directions or a spiral.

[0064] In this embodiment, the inner wall of the dustproof lip 122 may be provided with a bidirectional airflow structure 140, which forms a directional airflow pointing outward during operation, effectively "blowing" dust and moisture away from the sealing area, forming an air barrier protective layer, and further enhancing the overall dustproof and sealing performance. At the same time, the skeleton 110 is embedded in the elastic sealing ring 120, providing support for the entire oil seal structure 100, and maintaining stable sealing contact pressure and geometry.

[0065] In one embodiment of the present invention, reference is made to... Figure 4 The bidirectional airflow structure 140 may include a first airflow guide protrusion 141 and a second airflow guide protrusion 142. The first airflow guide protrusion 141 and the second airflow guide protrusion 142 protrude from the side of the dustproof lip 122 facing the main sealing lip 121 and are spaced apart circumferentially along the dustproof lip 122. Both the first airflow guide protrusion 141 and the second airflow guide protrusion 142 are inclined relative to the axial direction of the elastic sealing ring 120, and their inclination directions are opposite. This effectively disturbs the surrounding air; regardless of whether the rotation is clockwise or counterclockwise, the corresponding airflow guides the airflow, forming a continuous directional airflow pointing towards the external environment in the outer region of the sealing interface. This blows away and blocks external dust, water mist, splashes, and other contaminants, improving the sealing performance.

[0066] In one embodiment, the first guide protrusion 141 and the second guide protrusion 142 can be designed with equal width and height in their respective extended directions. That is, the width and height of the first guide protrusion 141 are the same at different positions, and the width and height of the second guide protrusion 142 are the same at different positions, so that they can be evenly distributed on the inner circumference of the elastic sealing ring 120, thereby better improving the flow guidance effect. Of course, it is understood that due to the influence of factors such as manufacturing process, the first guide protrusion 141 and the second guide protrusion 142 cannot achieve an absolutely equal height and width design in the actual product, and there will be a certain design tolerance. In addition, the first guide protrusion 141 and the second guide protrusion 142 can also be designed with other possible shapes, which can be determined according to the actual situation. This specification does not limit this embodiment.

[0067] In this embodiment, the cross-sectional shape of the first guide protrusion 141 and the second guide protrusion 142 can be an isosceles triangle, a semicircle, a trapezoid, or a racetrack shape. The specific shape can be determined according to the actual situation, and this embodiment does not limit it.

[0068] In one embodiment of the present invention, reference is made to... Figure 6The cross-section of at least one of the first guide protrusion 141 and the second guide protrusion 142 protrudes from the dustproof lip 122 by a height h, where 0.07 mm ≤ h ≤ 0.09 mm. It can be understood that the protrusion height of the first guide protrusion 141 can be h, or the protrusion height of the second guide protrusion 142 can be h, or both the first guide protrusion 141 and the second guide protrusion 142 can have a protrusion height of h. This better prevents contaminants from entering the dustproof lip 122, reduces wear on the main sealing lip 121, and simultaneously generates a weak, inward-pointing pumping effect, returning the grease to ensure good lubrication of the main sealing lip 121, preventing premature failure due to dry friction, and thus improving sealing performance. Optionally, the protrusion height h can be 0.07 mm, 0.075 mm, 0.08 mm, 0.085 mm, or 0.09 mm, and is not limited here.

[0069] It should be noted that the protrusion height of the guide protrusion referred to in this embodiment can be the maximum height protruding from the dustproof lip 122. During measurement, the radial protrusion height can be measured using the surface of the dustproof lip 122 that has not undergone elastic deformation as the measurement reference. In some embodiments, due to manufacturing processes, the top of the first guide protrusion 141 or the second guide protrusion 142 may be arc-shaped or other irregularly shaped. In this case, the protrusion height h of the first guide protrusion 141 or the second guide protrusion 142 can also be the normal distance between the intersection point of the tangents on both sides of the guide protrusion's cross-section and the surface of the dustproof lip 122 that has not undergone elastic deformation. Figure 6 The h shown in the figure.

[0070] In one embodiment of the present invention, reference is made to... Figure 6 At least one of the first guide protrusion 141 and the second guide protrusion 142 has two opposing second planes 1411 and a second arc surface 1412 connecting the two second planes 1411. Thus, the relatively gentle second arc surface 1412 can guide air to flow smoothly along its curvature, reducing eddy current generation; while the two second planes 1411 can effectively drive more air, which is beneficial for forming a stable and concentrated directional airflow pointing outward. It can be understood that the first guide protrusion 141 has a second plane 1411 and a second arc surface 1412, or the second guide protrusion 142 may have a second plane 1411 and a second arc surface 1412, or each of the first guide protrusion 141 and the second guide protrusion 142 may have a second plane 1411 and a second arc surface 1412 respectively.

[0071] Reference Figure 6The radius of the circle containing the second arc surface 1412 is R2, where 0.09 mm ≤ R2 ≤ 0.11 mm. Optionally, the radius of the circle containing the second arc surface 1412 can be 0.09 mm, 0.1 mm, or 0.11 mm, and is not limited here. And / or, the included angle between the two second planes 1411 is γ, where 132 degrees ≤ γ ≤ 138 degrees. Optionally, the included angle between the two second planes 1411 can be 132 degrees, 133 degrees, 134 degrees, 135 degrees, 136 degrees, 137 degrees, or 138 degrees, and is not limited here. Thus, by combining the radius and the included angle, turbulence generation can be reduced, while avoiding a decrease in flow velocity due to excessively large angles.

[0072] In one embodiment of the present invention, reference is made to... Figure 4 The main sealing lip 121 and the dustproof lip 122 intersect at a second intersection line 152. At least one of the first and second guide protrusions 141 forms an angle θ with the second intersection line 152, where 56 degrees ≤ θ ≤ 62 degrees. It can be understood that the angle between the first guide protrusion 141 and the second intersection line 152 can be θ, or the angle between the second guide protrusion 142 and the second intersection line 152 can both be θ. This facilitates the generation of outward-directing airflow near the dustproof lip 122, effectively "blowing" dust and moisture away from the sealing area. Optionally, the angle θ can be 56 degrees, 57 degrees, 58 degrees, 59 degrees, 60 degrees, 61 degrees, 62 degrees, etc., and is not limited here.

[0073] In one embodiment of the present invention, reference is made to... Figure 4 The extension length of at least one of the first guide protrusion 141 and the second guide protrusion 142 is L2, where 1 mm ≤ L2 ≤ 1.5 mm. It can be understood that the extension length of the first guide protrusion 141 is L2, or the extension length of the second guide protrusion 142 is L2, or the extension lengths of both the first guide protrusion 141 and the second guide protrusion 142 are L2. This better prevents contaminants from entering the dustproof lip 122, reduces wear on the main sealing lip 121, and simultaneously generates a weak, inward-pointing pumping effect, returning the grease to ensure good lubrication of the main sealing lip 121, preventing premature failure due to dry friction, and thus improving sealing performance. Optionally, the extension length L2 can be 1 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, or 1.5 mm, and is not limited here.

[0074] In one embodiment, with the shaft diameter of the oil seal being 68 mm, the seat hole diameter of the oil seal being 78 mm, and the oil sealing height being 5 mm, the oil seal structure proposed in this embodiment has a height H=0.03 mm for the first return oil line and the second return oil line, a height h=0.08 mm for the first guide protrusion 141 and the second guide protrusion 142, a height L2=1.2 mm, a height θ=58 degrees, and operates at a maximum speed of 0.344 m / s under forward and reverse rotation conditions, and has not leaked for 5264.5 hours.

[0075] It should be noted that the structure of the second flow guide protrusion 142 can be the same as that of the first flow guide protrusion 141.

[0076] In one embodiment of the present invention, the inner wall surface of the elastic sealing ring 120 is provided with a friction-reducing coating. This significantly reduces the coefficient of friction, directly improving wear resistance and service life, and reducing the risk of aging due to friction. Simultaneously, it possesses excellent self-lubricating properties, maintaining effective lubrication even under harsh operating conditions where the grease film is temporarily insufficient, preventing damage caused by dry friction. Furthermore, its excellent non-stick surface effectively prevents the adhesion and accumulation of impurities such as sludge and dust, maintaining the cleanliness of the lip for a long time. Optionally, the friction-reducing coating is made of PTFE (polytetrafluoroethylene).

[0077] In a preferred embodiment, the synergistic effect of the ultra-low height and high density of the return oil line can achieve a better siphon effect in low-speed scenarios. Specifically, refer to the table below.

[0078] Table 1 shows a comparison between the oil seal structure proposed in this application and the conventional oil seal structure under the same rate.

[0079]

[0080] Table 1 As can be seen from Table 1, the following conditions apply: linear velocity at the output end not exceeding 1 m / s, rotational speed not exceeding 100 r / min, frequent start-stop, or joint acceleration not exceeding 3000 ° / s². 2 In low-speed conditions, or under conditions of frequent forward and reverse rotation, the oil seal structure proposed in this application is more likely to form a sealing oil film to prevent oil leakage; while the oil seal structure without a return line will leak oil under low-speed conditions.

[0081]

[0082] Table 2 Table 2 compares the different heights of the first and second oil return lines in the oil seal structure proposed in this embodiment under the conditions of a shaft diameter of 68 mm, a seat hole diameter of 78 mm, and an oil sealing height of 5 mm. The first and second oil return lines are at the same height. The table shows that significant oil leakage occurs when the height of the first and second oil return lines is less than 0.02 mm or greater than 0.04 mm. Therefore, the oil return line height proposed in this embodiment provides better sealing under low-speed conditions and can better prevent oil leakage.

[0083]

[0084] Table 3 Table 3 shows a comparative test of the oil seal structure proposed in this embodiment at different speeds, with the shaft diameter of the oil seal being 68 mm, the seat hole diameter for oil seal installation being 78 mm, and the oil sealing height being 5 mm. The heights of the first and second oil return lines are 0.02 mm, 0.03 mm, and 0.04 mm, respectively. The data in the table shows that the oil seal structure proposed in this embodiment is more suitable for low-speed operating conditions and can achieve better oil leakage prevention.

[0085]

[0086] Table 4 Table 4 shows a comparative test of the guide protrusion height proposed in this embodiment under the conditions that the shaft diameter of the oil seal is 68 mm, the diameter of the seat hole for oil seal installation is 78 mm, the oil sealing height is 5 mm, and the height of the first and second oil return lines on the main sealing lip is 0.03 mm. As can be seen from the table, when the height of the guide protrusion is greater than or equal to 0.07 mm and less than or equal to 0.1 mm, no oil leakage occurs, and the sealing effect is better.

[0087] To achieve the above objectives, refer to Figure 1 and Figure 2 This invention provides a harmonic reducer, comprising a flexible wheel 200, a bearing 300, a rigid wheel 400, and the aforementioned oil seal structure 100. The flexible wheel 200 and the rigid wheel 400 are rotatably connected. The bearing 300 is disposed between the flexible wheel 200 and the rigid wheel 400 and has a mounting groove. The oil seal structure 100 is disposed in the mounting groove. The linear velocity at the output end of the harmonic reducer is less than or equal to 1 m / s or the rotational speed is less than or equal to 100 r / min. Specifically, the specific structure of the oil seal structure is as described in the above embodiments. Since this harmonic reducer adopts all the technical solutions of the above embodiments, it possesses at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be elaborated further here.

[0088] To achieve the above objectives, this invention provides a robot comprising a robot body and a harmonic reducer connected to the robot body, wherein the harmonic reducer is the type described above. Specifically, the specific structure of the harmonic reducer is as described in the above embodiments. Since this robot employs all the technical solutions of the above embodiments, it possesses at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be elaborated upon further here.

[0089] The above description is merely an exemplary embodiment of the present invention and does not limit the scope of protection of the embodiments of the present invention. Any equivalent structural transformations made under the technical concept of the present invention using the description and drawings of the embodiments of the present invention, or direct / indirect applications in other related technical fields, are included within the scope of protection of the embodiments of the present invention.

Claims

1. An oil seal structure, characterized in that, The oil seal structure includes: skeleton; An elastic sealing ring, wherein the skeleton is embedded in the elastic sealing ring, and the inner wall of the elastic sealing ring has a main sealing lip and a dustproof lip spaced apart; wherein, The air side of the main sealing lip is provided with multiple sets of bidirectional oil return structures distributed circumferentially. The bidirectional oil return structure includes multiple parallel first oil return lines and multiple parallel second oil return lines. The first oil return lines and the second oil return lines extend obliquely relative to the axial direction of the elastic sealing ring and in opposite directions. The first oil return lines and the second oil return lines are spaced apart. The height H of the first oil return line and / or the second oil return line protruding from the main sealing lip is 0.02 mm ≤ H ≤ 0.04 mm.

2. The oil seal structure as described in claim 1, characterized in that, The first return oil line and the second return oil line are symmetrically arranged along the axial direction; and / or, the first return oil line and the second return oil line have the same height; and / or, the number of the first return oil line and the number of the second return oil line are the same.

3. The oil seal structure as described in claim 1, characterized in that, At least one of the first return oil line and the second return oil line has a cross-section having two opposing first planes and a first arc surface connecting the two first planes; The radius of the circle containing the first arc surface is R1, 0.04 mm ≤ R1 ≤ 0.06 mm; and / or, the included angle between the two first planes is α, 117 degrees ≤ α ≤ 123 degrees.

4. The oil seal structure as described in claim 1, characterized in that, In each set of the bidirectional oil return structures, the number of the first oil return line and / or the second oil return line is 10 to 11. And / or, the interval between two adjacent first return oil lines and the interval between two adjacent second return oil lines are both d, 0.45 mm ≤ d ≤ 0.5 mm.

5. The oil seal structure as described in claim 1, characterized in that, The main sealing lip has an oil side and an air side, which intersect at a first intersection line. The angle between at least one of the first return oil line and the second return oil line and the first intersection line is β, where 19 degrees ≤ β ≤ 21 degrees.

6. The oil seal structure as described in claim 5, characterized in that, The bidirectional oil return structure satisfies the following functional relationship: C1 = (1.2 ~ 1.5) d / sinβ, and C1≥1 mm; Wherein, C1 is the distance between the first and second oil return lines in two adjacent sets of bidirectional oil return structures at the end furthest from the dustproof lip.

7. The oil seal structure as described in claim 1, characterized in that, The extension length of at least one of the first return oil line and the second return oil line is L1, where 6 mm ≤ L1 ≤ 8 mm.

8. The oil seal structure as described in claim 1, characterized in that, The dustproof lip has multiple sets of bidirectional airflow guiding structures distributed circumferentially on one side wall facing the main sealing lip, which are used to form airflow pointing towards the external environment.

9. The oil seal structure as described in claim 8, characterized in that, The bidirectional flow-guiding structure includes a first flow-guiding protrusion and a second flow-guiding protrusion. The first flow-guiding protrusion and the second flow-guiding protrusion are protruding on the side of the dustproof lip facing the main sealing lip and are spaced apart along the circumference of the dustproof lip. The first flow-guiding protrusion and the second flow-guiding protrusion are inclined relative to the axial direction of the elastic sealing ring and the inclination directions are opposite. The height of at least one of the first and second guide protrusions protruding from the dustproof lip is h, where 0.07 mm ≤ h ≤ 0.09 mm.

10. The oil seal structure as described in claim 9, characterized in that, At least one of the first and second guide protrusions has a cross-section with two opposing second planes and a second arc surface connecting the two second planes; The radius of the circle containing the second arc surface is R2, 0.09 mm ≤ R2 ≤ 0.11 mm; and / or, the included angle between the two second planes is γ, 132 degrees ≤ γ ≤ 138 degrees.

11. The oil seal structure as described in claim 9, characterized in that, The main sealing lip and the dustproof lip intersect at a second intersection line, and the angle between at least one of the first guide protrusion and the second guide protrusion and the second intersection line is θ, where 56 degrees ≤ θ ≤ 62 degrees; and / or The extension length of at least one of the first guide protrusion and the second guide protrusion is L2, where 1 mm ≤ L2 ≤ 1.5 mm.

12. The oil seal structure according to any one of claims 1 to 11, characterized in that, The inner wall surface of the elastic sealing ring is provided with a friction-reducing coating.

13. A harmonic reducer, characterized in that, The harmonic reducer includes a flexible wheel, a bearing, a rigid wheel, and an oil seal structure as described in any one of claims 1 to 12. The flexible wheel and the rigid wheel are rotatably connected. The bearing is disposed between the flexible wheel and the rigid wheel. The bearing has a mounting groove. The oil seal structure is disposed in the mounting groove. The linear velocity at the output end of the harmonic reducer is less than or equal to 1 m / s or the rotational speed is less than or equal to 100 r / min.

14. A robot, characterized in that, The robot includes a robot body and a harmonic reducer connected to the robot body, wherein the harmonic reducer is the harmonic reducer as described in claim 13.

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