Sealing structure and harmonic reducer

Abstract

The utility model discloses a sealing structure and a harmonic speed reducer, and relates to the technical field of speed reducers, the sealing structure is used for the harmonic speed reducer, the sealing structure comprises a crossed roller bearing and a framework oil seal, and the crossed roller bearing comprises a bearing inner ring and a bearing outer ring which are arranged at an interval; a first annular surface, a ball groove surface, a second annular surface and a third annular surface are sequentially formed on the inner peripheral wall of the bearing outer ring in the axial direction of the bearing outer ring, and a groove is formed in the third annular surface; the framework oil seal sleeves the bearing inner ring and is arranged between the groove wall of the groove and the peripheral wall of the bearing inner ring in a sealing manner; wherein the distance from the first annular surface to the outer peripheral wall of the bearing inner ring is B1, the distance from the second annular surface to the outer peripheral wall of the bearing inner ring is B2, and B2 is smaller than B1. The utility model aims to improve the sealing performance of the lubricant in the harmonic speed reducer.

Description

Technical Field

[0001] The utility model relates to the technical field of reducers, in particular to a sealing structure and a harmonic reducer. Background Art

[0002] Harmonic reducer is a new type of reducer developed based on the transmission principle of using the controllable elastic deformation of flexible elements to transmit motion and power. It has the advantages of large transmission ratio, small size, high precision, large load capacity, etc. Crossed roller bearings have multiple advantages in harmonic reducers, including high load capacity, high rigidity, small friction loss and high speed performance, high positioning accuracy, compact structure, easy installation, etc.

[0003] The harmonic reducer of crossed roller bearing mainly includes a housing, a wave generator, a flexspline, a rigid wheel and a crossed roller bearing; the wave generator is connected to the inner side of the flexspline through a flexible bearing, and the inner wall of the rigid wheel is partially meshed with the outer wall of the flexspline; when in use, the wave generator can drive the flexible bearing to rotate and produce periodic deformation when it rotates, thereby driving the flexspline to produce periodic deformation, so that different parts of the flexspline periodically mesh with the rigid wheel. Due to the tooth difference between the flexspline and the rigid wheel, the flexspline will rotate relative to the rigid wheel, thereby achieving the purpose of deceleration.

[0004] In the structure of the harmonic reducer with crossed roller bearings, lubricant is usually added to the bearings to reduce noise, wear, etc. of the reducer. If there is too little lubricant, the frequency of adding needs to be increased, which is time-consuming and labor-intensive. However, if too much lubricant is added, the lubricant is likely to leak to the outside, thereby interfering with the operation of components such as motors. Utility Model Content

[0005] The main purpose of the utility model is to provide a sealing structure and a harmonic reducer, aiming at improving the sealing performance of the lubricant in the harmonic reducer.

[0006] In order to achieve the above object, the utility model proposes a sealing structure, which includes:

[0007] A cross roller bearing, the cross roller bearing comprising a bearing inner ring and a bearing outer ring arranged at intervals, the inner peripheral wall of the bearing outer ring being formed with a first annular surface, a ball groove surface, a second annular surface and a third annular surface in sequence along the axial direction of the bearing outer ring, the third annular surface being provided with a groove; and

[0008] A skeleton oil seal, wherein the skeleton oil seal is sleeved on the inner ring of the bearing and is sealed between the groove wall of the groove and the outer peripheral wall of the inner ring of the bearing;

[0009] The distance from the first annular surface to the outer peripheral wall of the inner ring of the bearing is B1, and the distance from the second annular surface to the outer peripheral wall of the inner ring of the bearing is B2, and B2<B1.

[0010] In one embodiment, B2<B1 / 2.

[0011] In one embodiment, B1<0.4 mm, B2<0.4 mm.

[0012] In one embodiment, the outer peripheral wall of the bearing inner ring is formed with a mounting shaft surface, and the skeleton oil seal is sealed between the groove wall of the groove and the mounting shaft surface; wherein the roughness of the mounting shaft surface is Ra, 0.19<Ra<0.4.

[0013] In one embodiment, 0.2≤Ra≤0.3.

[0014] In one embodiment, the skeleton oil seal includes a main body and a sealing lip, wherein the sealing lip is arranged on a side of the main body close to the bottom wall of the groove, and the sealing lip abuts against the outer peripheral wall of the bearing inner ring.

[0015] In one embodiment, a wear-resistant layer is provided on a side of the sealing lip close to the bearing inner ring.

[0016] In one embodiment, the wear-resistant layer is a PTFE coating.

[0017] The utility model also provides a harmonic reducer, and the harmonic reducer comprises the sealing structure as described above.

[0018] In one embodiment, the harmonic reducer further includes a flexible wheel and a rigid wheel, a mounting shaft is formed on one side of the flexible wheel, the rigid wheel is sleeved on and meshed with the mounting shaft, and the inner ring of the bearing is sleeved on the mounting shaft and located between the flexible wheel and the rigid wheel.

[0019] The technical solution of the utility model adopts a cross roller bearing and a skeleton oil seal to form a sealing structure. The cross roller bearing comprises a bearing inner ring and a bearing outer ring which are arranged at intervals. The inner peripheral wall of the bearing outer ring is formed with a first annular surface, a ball groove surface, a second annular surface and a third annular surface in sequence along the axial direction of the bearing outer ring. The third annular surface is provided with a groove. The skeleton oil seal is sleeved on the bearing inner ring, and the seal is provided between the groove wall of the groove and the outer peripheral wall of the bearing inner ring. The distance from the first annular surface to the outer peripheral wall of the bearing inner ring is B1, and the distance from the second annular surface to the outer peripheral wall of the bearing inner ring is B2. Since B2 is less than B1, that is, the gap on one side of the bearing inner ring and the bearing outer ring close to the skeleton oil seal is smaller than the gap on the side away from the skeleton oil seal. Therefore, the pressure in the gap on the one side of the bearing inner ring and the bearing outer ring close to the skeleton oil seal is lower than the pressure in the gap on the side away from the skeleton oil seal, thereby preventing the partial structure of the skeleton oil seal from being deformed due to excessive pressure, and effectively reducing the risk of lubricant leakage. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0021] Figure 1 A structural schematic diagram of an embodiment of a sealing structure provided by the utility model;

[0022] Figure 2 A schematic structural diagram of an embodiment of a cross roller bearing provided by the utility model;

[0023] Figure 3 A schematic structural diagram of an embodiment of a skeleton oil seal provided by the utility model;

[0024] Figure 4 A schematic structural diagram of an embodiment of a harmonic reducer provided by the utility model;

[0025] Figure 5 The present invention is a schematic structural diagram of another embodiment of the harmonic reducer provided by the utility model.

[0026] Description of Figure Numbers:

[0027] 100. Sealing structure; 1. Cross roller bearing; 11. Bearing inner ring; 111. Mounting shaft surface; 12. Bearing outer ring; 121. Groove; 122. First annular surface; 123. Ball groove surface; 124. Second annular surface; 125. Third annular surface; 2. Skeleton oil seal; 21. Main body; 22. Sealing lip;

[0028] 1000, harmonic reducer; 200, flexible wheel; 300, rigid wheel.

[0029] The realization of the purpose, functional features and advantages of the utility model will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0031] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back...), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture. If the specific posture changes, the directional indications will also change accordingly.

[0032] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the utility model, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features limited to "first" and "second" may explicitly or implicitly include at least one of the features. In addition, if "and / or" or "and / or" appears in the full text, its meaning includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or solutions that satisfy both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the utility model.

[0033] The utility model provides a sealing structure 100 .

[0034] See also Figure 1 and Figure 2In one embodiment of the utility model, the sealing structure 100 includes a cross roller bearing 1 and a skeleton oil seal 2, wherein the cross roller bearing 1 includes a bearing inner ring 11 and a bearing outer ring 12 which are arranged at intervals, and the inner circumferential wall of the bearing outer ring 12 is sequentially formed with a first annular surface 122, a ball groove surface 123, a second annular surface 124 and a third annular surface 125 along the axial direction of the bearing outer ring 12, and the third annular surface 125 is provided with a groove 121; the skeleton oil seal 2 is sleeved on the bearing inner ring 11, and the seal is arranged between the groove wall of the groove 121 and the outer circumferential wall of the bearing inner ring 11; wherein the distance from the first annular surface 122 to the outer circumferential wall of the bearing inner ring 11 is, and the distance from the second annular surface 124 to the outer circumferential wall of the bearing inner ring 11 is B2, and B2<B1.

[0035] The technical solution of the utility model adopts a cross roller bearing 1 and a skeleton oil seal 2 to form a sealing structure 100. The cross roller bearing 1 includes a bearing inner ring 11 and a bearing outer ring 12 arranged at intervals. The inner peripheral wall of the bearing outer ring 12 is formed with a first annular surface 122, a ball groove surface 123, a second annular surface 124 and a third annular surface 125 in sequence along the axial direction of the bearing outer ring 12. The third annular surface 125 is provided with a groove 121. The skeleton oil seal 2 is sleeved on the bearing inner ring 11, and the seal is arranged between the groove wall of the groove 121 and the outer peripheral wall of the bearing inner ring 11. The first annular surface 122 The distance to the outer peripheral wall of the bearing inner ring 11 is B1, and the distance from the second annular surface 124 to the outer peripheral wall of the bearing inner ring 11 is B2. Since B2 is less than B1, that is, the gap on the side of the bearing inner ring 11 and the bearing outer ring 12 close to the skeleton oil seal 2 is smaller than the gap on the side away from the skeleton oil seal 2. Therefore, the pressure in the gap on the side of the bearing inner ring 11 and the bearing outer ring 12 close to the skeleton oil seal 2 will be lower than the pressure in the gap on the side away from the skeleton oil seal 2, thereby preventing some structures of the skeleton oil seal 2 from being deformed due to excessive pressure, and effectively reducing the risk of lubricant leakage.

[0036] In order to further alleviate the pressure on a part of the structure of the skeleton oil seal 2 , in one embodiment of the present application, B2<B1 / 2.

[0037] Furthermore, in an embodiment of the present application, B1 is less than 0.4 mm, and B2 is less than 0.4 mm. Generally speaking, the clearance between the inner and outer rings of a conventional cross roller bearing 1 is 1 mm. By reducing the clearance, not only can the grease or lubricating oil be more easily formed into an effective lubricating film inside the bearing, and thus more easily retained by the bearing, the oil storage capacity of the cross roller bearing 1 itself can be improved, but also the pressure fluctuation inside the sealing cavity can be reduced, and the risk of leakage caused by excessive pressure can be reduced.

[0038] Since the roughness of the mounting surface is too large or too small, it will affect the sealing performance and wear degree of the skeleton oil seal 2. Therefore, in one embodiment of the present application, the outer peripheral wall of the bearing inner ring 11 is formed with a mounting shaft surface 111, and the skeleton oil seal 2 is sealed between the groove wall of the groove 121 and the mounting shaft surface 111; wherein the roughness of the mounting shaft surface 111 is Ra, 0.19<Ra<0.4. A further preferred range is 0.2≤Ra≤0.3, which has an excellent effect on reducing the wear degree of the skeleton oil seal 2.

[0039] In one embodiment of the present application, the skeleton oil seal 2 includes a main body 21 and a sealing lip 22, wherein the sealing lip 22 is disposed on one side of the main body 21 close to the bottom wall of the groove 121, and the sealing lip 22 abuts against the outer peripheral wall of the bearing inner ring 11. In this way, the skeleton oil seal 2 can better contact the outer peripheral wall of the bearing inner ring 11, thereby forming an effective seal, preventing lubricating oil or grease from leaking from the inside of the bearing, and preventing external contaminants from entering the inside of the bearing, thereby extending the service life of the bearing and improving performance stability.

[0040] In one embodiment of the present application, a wear-resistant layer is provided on the side of the sealing lip 22 close to the bearing inner ring 11, and the wear-resistant layer can improve the wear resistance of the sealing lip 22, improve the clamping force and increase the service life of the oil seal, thereby optimizing the sealing performance of the skeleton oil seal 2. The wear-resistant layer is often made of wear-resistant materials, such as fluororubber (FPM), polytetrafluoroethylene (PTFE), etc. PTFE material is preferably used, which not only has excellent wear resistance, can reduce friction and wear when in contact with the bearing surface, but also has excellent corrosion resistance and high temperature resistance, thereby being able to adapt to the working environment of the bearing.

[0041] The utility model also provides a harmonic reducer 1000, which includes a sealing structure 100. The specific structure of the sealing structure 100 refers to the above-mentioned embodiment. Since the harmonic reducer 1000 adopts all the technical solutions of all the above-mentioned embodiments, it has at least all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be described one by one here.

[0042] Furthermore, the harmonic reducer 1000 also includes a flexible spline 200 and a rigid spline 300, a mounting shaft is formed on one side of the flexible spline 200, the rigid spline 300 is sleeved on the mounting shaft and meshed with the mounting shaft, and the bearing inner ring 11 is sleeved on the mounting shaft and located between the flexible spline 200 and the rigid spline 300.

[0043] In the embodiment of the utility model, the crossed roller bearing 1 and the skeleton oil seal 2 are regarded as the entire sealing structure 100, and the inner and outer ring clearance of the crossed roller bearing 1 is limited to less than 0.4 mm, and B2 is limited to B1 / 2; the roughness of the oil seal mounting shaft surface 111 of the crossed roller bearing 1 is limited from 0.1≤Ra≤0.32 to 0.19<Ra<0.4, and the further preferred range is 0.2≤Ra≤0.3, and the skeleton oil seal 2 with a sealing lip 22 coated with PTFE coating is used for sealing. On the one hand, the internal pressure of the sealing cavity formed by the crossed roller bearing 1 and the skeleton oil seal 2 can be reasonably controlled, and on the other hand, the wear of the sealing lip 22 of the skeleton oil seal 2 can be alleviated, which is conducive to forming a more stable sealing environment, and can greatly improve the sealing performance of the harmonic reducer 1000.

[0044] The above description is only an exemplary embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the technical concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A sealing structure for a harmonic reducer, characterized in that: The sealing structure comprises: A cross roller bearing, the cross roller bearing comprising a bearing inner ring and a bearing outer ring arranged at intervals, the inner peripheral wall of the bearing outer ring being formed with a first annular surface, a ball groove surface, a second annular surface and a third annular surface in sequence along the axial direction of the bearing outer ring, the third annular surface being provided with a groove; and A skeleton oil seal, wherein the skeleton oil seal is sleeved on the inner ring of the bearing and is sealed between the groove wall of the groove and the outer peripheral wall of the inner ring of the bearing; The distance from the first annular surface to the outer peripheral wall of the inner ring of the bearing is B1, and the distance from the second annular surface to the outer peripheral wall of the inner ring of the bearing is B2, and B2<B1.

2. The sealing structure according to claim 1, characterized in that: B2<B1 / 2.

3. The sealing structure according to claim 2, characterized in that: B1<0.4mm, B2<0.4mm.

4. The sealing structure according to claim 1, characterized in that: The outer peripheral wall of the bearing inner ring is formed with a mounting shaft surface, and the skeleton oil seal is sealed between the groove wall of the groove and the mounting shaft surface; wherein the roughness of the mounting shaft surface is Ra, 0.19<Ra<0.

4.

5. The sealing structure according to claim 4, characterized in that: 0.2≤Ra≤0.

3.

6. The sealing structure according to any one of claims 1 to 5, characterized in that: The skeleton oil seal comprises a main body and a sealing lip. The sealing lip is arranged on one side of the main body close to the bottom wall of the groove, and the sealing lip abuts against the outer peripheral wall of the bearing inner ring.

7. The sealing structure according to claim 6, characterized in that: A wear-resistant layer is provided on one side of the sealing lip close to the bearing inner ring.

8. The sealing structure according to claim 7, characterized in that: The wear-resistant layer is a PTFE coating.

9. A harmonic reducer, characterized in that: The harmonic reducer includes the sealing structure according to any one of claims 1 to 8.

10. The harmonic reducer according to claim 9, characterized in that: The harmonic reducer also includes a flexible wheel and a rigid wheel. A mounting shaft is formed on one side of the flexible wheel. The rigid wheel is sleeved on and meshed with the mounting shaft. The inner ring of the bearing is sleeved on the mounting shaft and located between the flexible wheel and the rigid wheel.

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