Harmonic reducer with high bearing capacity and high rigidity

Abstract

The harmonic reducer comprises a wave generator, a flexible gear, a rigid gear, an outer end cover, a framework oil seal and a load bearing, the wave generator is installed on the inner side of the flexible gear, the rigid gear is connected with the outer end cover through threads, the flexible gear is connected with the load bearing through threads, and the framework oil seal is installed on the outer end cover. The load bearing is of a cross bearing structure, and the outer end cover and the load bearing are connected in a glue adhesion mode. Compared with the prior art, the harmonic reducer has the advantages that the bearing capacity and the rigidity of the harmonic reducer are improved, and the like.

Description

Technical Field

[0001] The utility model relates to a harmonic reducer, in particular to a harmonic reducer with high load-bearing capacity and high rigidity. Background Art

[0002] Harmonic reducers are widely used in the field of robotics due to their advantages of smooth transmission, small size, light weight, low noise, high transmission efficiency and high transmission accuracy, especially in collaborative robots and humanoid robots. With the development of robotics technology, various industries have increasingly stringent requirements for harmonic reducers, especially micro harmonic reducers.

[0003] Micro harmonic reducers in the existing market generally use four-point contact ball bearings as output-end load bearings. Although such bearings have certain load-bearing capacity and rotational flexibility, when faced with high-load applications that require high-precision transmission, the load-bearing capacity and rigidity are relatively insufficient due to the limited number of contact points, which in turn affects the overall performance of the reducer.

[0004] After searching, Chinese patent publication number CN108061139A discloses a micro harmonic reducer, including a housing, a bearing outer ring, a bearing inner ring, a rigid wheel, a flexible wheel, a flexible bearing, a wave generator, a shell head inner gear ring, a shell tail inner thread, a rigid wheel inner gear ring, a rigid wheel outer gear ring, a flexible head outer gear ring, a flexible tail outer thread, a bearing outer thread and a bearing inner thread. However, the existing patent uses rolling bearings, which still have problems such as insufficient load-bearing capacity and stiffness. Utility Model Content

[0005] The purpose of the utility model is to overcome the defects of the above-mentioned prior art and provide a harmonic reducer with high load-bearing capacity and high rigidity, so that the output end bearing can withstand a larger load during the transmission process, thereby improving the load-bearing capacity and rigidity of the micro harmonic reducer.

[0006] The purpose of the utility model can be achieved through the following technical solutions:

[0007] According to one aspect of the utility model, a harmonic reducer with high load-bearing capacity and high rigidity is provided, comprising a wave generator, a flexible wheel, a rigid wheel, an outer end cover, a skeleton oil seal and a load bearing, wherein the wave generator is installed on the inner side of the flexible wheel, the rigid wheel and the outer end cover are connected by threads, the flexible wheel and the load bearing are connected by threads, the load bearing adopts a cross bearing structure, and the outer end cover and the load bearing are connected by glue bonding.

[0008] As a preferred technical solution, the load bearing comprises an inner ring, an outer ring and cylindrical rollers, and the cylindrical rollers are arranged crosswise and vertically in a raceway correspondingly formed between the inner ring and the outer ring.

[0009] As a preferred technical solution, the first internal thread of the inner ring cooperates with the first external thread of the outer end surface of the bottom of the flexible wheel cup.

[0010] As a preferred technical solution, the outer ring and the outer end cover are gap-fitted and connected with adhesive.

[0011] As a preferred technical solution, a U-shaped glue storage groove is provided at the inner hole of the outer end cover.

[0012] As a preferred technical solution, the outer end surface of the inner ring is provided with an outer rolling groove, the inner hole of the outer ring is provided with an inner rolling groove, and the cylindrical rollers are arranged crosswise in the rolling grooves using full rollers.

[0013] As a preferred technical solution, the outer ring and the inner hole on one side of the outer end cover adopt a D7 / h6 clearance fit.

[0014] As a preferred technical solution, the outer end surface of the rigid wheel is processed with a second external thread, the inner hole of the outer end cover is processed with a second internal thread, and a threaded connection is formed between the second external thread and the second internal thread.

[0015] As a preferred technical solution, the outer diameter of the harmonic reducer is ≤25 mm, and the modulus m of the rigid wheel and the flexible wheel is ≤0.3.

[0016] As a preferred technical solution, the flex spline includes a flex spline tooth portion, the rigid spline includes a rigid spline tooth portion, and the flex spline tooth portion and the rigid spline tooth portion form inter-tooth transmission.

[0017] Compared with the prior art, the utility model has the following advantages:

[0018] 1) The load bearing of the utility model adopts a cross bearing structure. Compared with the traditional four-point contact ball bearing, the rolling element in the middle of the bearing is a cylindrical roller, and a full roller cross arrangement design is adopted, which can effectively improve the rigidity of the harmonic reducer.

[0019] 2) The outer end cover and the outer ring of the load bearing of the utility model are connected by glue bonding. Compared with threaded connection, the stress distribution at the adhesive connection is more uniform, thereby improving the vibration and noise of the bearing. A glue storage groove is processed at the end of the inner hole of the outer end cover, which can maintain the uniform distribution and flow of glue in the groove, avoid unstable flow or precipitation of glue, and thus improve the strength and stability of the adhesive connection.

[0020] 3) The utility model uses a threaded connection between the flexible wheel and the inner ring of the load bearing. The inner ring of the load bearing is processed with an internal thread, and the outer end surface of the flexible wheel cup bottom is processed with an external thread. Since no additional threaded holes are required, the volume of the bearing is reduced, thereby reducing the overall size of the micro harmonic reducer. There is a positioning column at the front end of the internal thread of the inner ring of the bearing, which is axially positioned with the stepped shaft of the flexible wheel cup bottom to ensure the accuracy requirements of the load bearing and the flexible wheel after assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a cross-sectional view of a harmonic reducer according to an embodiment of the utility model.

[0022] Figure 2 It is a cross-sectional view of a cross roller bearing in an example of the utility model.

[0023] FIG3( a ) is a cross-sectional view of the rigid wheel of the present invention.

[0024] FIG3( b ) is a cross-sectional view of the flexible wheel in the example of the present utility model.

[0025] Figure 4 The utility model is a threaded connection between a flexible wheel and a rigid wheel in an example.

[0026] Figure 5 It is the U-shaped groove of the outer end cover in the example of the utility model.

[0027] The attached marks in the figure are: 1-wave generator; 1a-flexible bearing; 1b-cam; 2-flexible wheel; 2a-first external thread; 2b-flexible wheel tooth; 3-rigid wheel; 3a-second external thread; 3b-rigid wheel tooth; 4-outer end cover; 4a-second internal thread; 4b-U-shaped groove; 5-skeleton oil seal; 6-load bearing; 6a-inner ring; 6b-outer ring; 6c-cylindrical roller; 6a1-outer rolling groove; 6b1-inner rolling groove; 6a2-first internal thread. DETAILED DESCRIPTION

[0028] 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 part of the embodiments of the utility model, not all of them. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the utility model.

[0029] like Figure 1As shown, a harmonic reducer with high load-bearing capacity and high rigidity includes a wave generator 1, a flexible wheel 2, a rigid wheel 3, a load bearing 6, an outer end cover 4, and a skeleton oil seal 5. The load bearing 6 includes an inner ring 6a, an outer ring 6b, and a cylindrical roller 6c. The cylindrical roller 6c is arranged crosswise and vertically on the raceway formed between the inner ring 6a and the outer ring 6b. The wave generator 1 is installed on the inner side of the flexible wheel 2. The flexible wheel 2 and the load bearing 6 are connected by threads. The external thread on the outer end surface of the cup bottom of the flexible wheel 2 is matched with the internal thread of the inner ring 6a of the load bearing 6. The outer ring 6b of the load bearing 6 is connected to the inner cavity of the outer end cover 4 by clearance fit and high-strength adhesive. A U-shaped adhesive storage tank is designed at the bonding location. The rigid wheel 3 and the outer end cover 4 are connected by threads. The external thread on the outer end surface of the rigid wheel 3 is matched with the internal thread in the inner cavity of the outer end cover 4. The flexible wheel tooth portion 2b and the rigid wheel tooth portion 3b form inter-tooth transmission.

[0030] The outer diameter of the miniature harmonic reducer of the utility model is ≤22mm, and the modulus m of the rigid wheel and the flexible wheel is ≤0.3;

[0031] like Figure 2 As shown, the load bearing 6 is a roller bearing, and the rolling element between the outer ring 6b and the inner ring 6a of the roller bearing is a cylindrical roller 6c. The outer ring 6b of the load bearing and the inner hole on the other side of the outer end cover 4 are clearance-matched; the inner hole of the outer ring 6b of the roller bearing is provided with an inner rolling groove 6b1, and the outer end surface of the inner ring 6a of the roller bearing is provided with an outer rolling groove 6a1, and the cylindrical roller 6c is arranged in a full roller cross in the rolling groove 6c1; the cross structure formed by the roller inside the bearing enables the bearing to effectively distribute and bear loads from different directions, including radial loads, axial loads and overturning moments. Due to the line contact between the roller and the inner and outer ring raceways, the local stress generated by the point contact is greatly reduced, and the bearing capacity and rigidity of the bearing are improved, thereby improving the rigidity and bearing capacity of the micro harmonic reducer.

[0032] See Figure 3. The inner hole of the inner ring of the bearing is processed with a first internal thread 6a2, and the boss of the bottom of the flexible wheel cup is processed with a first external thread 2a. The first external thread 2a of the bottom of the flexible wheel cup and the first internal thread 6a2 of the inner ring of the bearing form a threaded connection; the outer end surface of the rigid wheel is processed with a second external thread 3a, and the inner hole on the other side of the outer end cover is processed with a second internal thread 4a. Figure 4 A threaded connection is formed between the second external thread 3a of the outer end surface of the rigid wheel and the second internal thread 4a of the outer end cover. Since no additional threaded hole is required, the volume of the bearing is reduced, and while the assembly accuracy and high load requirements of the micro harmonic reducer are guaranteed, the overall size of the micro harmonic reducer is effectively reduced.

[0033] The gap formed by the outer ring of the load bearing and the inner hole of the outer end cover is filled with glue, so that the outer ring of the load bearing and the outer end cover are firmly connected; a U-shaped glue storage groove is provided at the inner hole of the outer end cover, such as Figure 5 As shown in the figure, the adhesive can cure quickly on the inert metal surface and has excellent load-bearing capacity and connection strength. The design of the U-shaped glue storage tank can maintain the uniform distribution and flow of the glue in the tank, avoid unstable flow or precipitation of the glue, and thus improve the strength and stability of the adhesive connection;

[0034] When the harmonic reducer of the utility model is in working state, the outer end cover 4 is fixed on the casing, the motor input shaft is axially fixed by the countersunk screw and the inner hole of the cam 1b of the wave generator 1, the motor drives the wave generator 1 to rotate at a uniform speed in the forward or reverse direction, and the outer ring of the flexible bearing 1a of the wave generator is elastically deformed alternately. Since the wave generator is assembled in the inner cavity of the flexible wheel 2, the flexible wheel 2 is forced to undergo elastic deformation, and the gear teeth in front of the meshing point of the flexible wheel 2 are gradually displaced forward relative to the tooth grooves of the rigid wheel 3, resulting in the flexible wheel teeth being squeezed back by the tooth grooves during the meshing process, and the flexible wheel 2 is pushed to rotate in the opposite direction of the wave generator 1. When the wave generator 1 rotates 360°, the flexible wheel 2 moves two teeth in the opposite direction of the wave generator 1. When the wave generator 1 continues to rotate, the above-mentioned movement process is repeated in a cycle, so that the flexible wheel 2 can continuously run in the reverse direction of the wave generator, and the bottom of the cup of the flexible wheel 2 is connected to the inner hole of the inner ring of the cross bearing by a thread, and the cross bearing can be connected to an external load, so that the reducer can operate with load.

[0035] The above is only a specific implementation of the utility model, but the protection scope of the utility model is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the utility model, and these modifications or replacements should be included in the protection scope of the utility model. Therefore, the protection scope of the utility model should be based on the protection scope of the claims.

Claims

1. A harmonic reducer with high load-bearing capacity and high rigidity, comprising a wave generator (1), a flexible wheel (2), a rigid wheel (3), an outer end cover (4), a skeleton oil seal (5) and a load bearing (6), wherein the wave generator (1) is mounted on the inner side of the flexible wheel (2), and the rigid wheel (3) is connected to the outer end cover (4) by a thread, characterized in that: The flexible wheel (2) and the load bearing (6) are connected via threads, the load bearing (6) adopts a cross bearing structure, and the outer end cover (4) and the load bearing (6) are connected by gluing.

2. A harmonic reducer with high load-bearing capacity and high rigidity according to claim 1, characterized in that: The load bearing (6) comprises an inner ring (6a), an outer ring (6b) and cylindrical rollers (6c), wherein the cylindrical rollers (6c) are arranged crosswise and perpendicularly on a raceway correspondingly formed between the inner ring (6a) and the outer ring (6b).

3. A harmonic reducer with high load-bearing capacity and high rigidity according to claim 2, characterized in that: The first internal thread (6a2) of the inner ring (6a) cooperates with the first external thread (2a) on the outer end surface of the cup bottom of the flexible wheel (2).

4. A harmonic reducer with high load-bearing capacity and high rigidity according to claim 2, characterized in that: The outer ring (6b) and the outer end cover (4) are clearance-matched and connected with adhesive.

5. A harmonic reducer with high load-bearing capacity and high rigidity according to claim 2, characterized in that: A U-shaped glue storage groove (4b) is provided at the inner hole of the outer end cover (4).

6. A harmonic reducer with high load-bearing capacity and high rigidity according to claim 2, characterized in that: The outer end surface of the inner ring (6a) is provided with an outer rolling groove (6a1), the inner hole of the outer ring (6b) is provided with an inner rolling groove (6b1), and the cylindrical rollers (6c) are arranged in a cross-shaped manner in the rolling grooves.

7. A harmonic reducer with high load-bearing capacity and high rigidity according to claim 2, characterized in that: The outer ring (6b) and the inner hole on one side of the outer end cover (4) are matched with a D7 / h6 clearance.

8. The harmonic reducer with high load-bearing capacity and high rigidity according to claim 1, characterized in that: The outer end surface of the rigid wheel (3) is processed with a second external thread (3a), and the inner hole of the outer end cover (4) is processed with a second internal thread (4a), and a threaded connection is formed between the second external thread (3a) and the second internal thread (4a).

9. A harmonic reducer with high load-bearing capacity and high rigidity according to claim 1, characterized in that: The outer diameter of the harmonic reducer is ≤25mm, and the modulus m of the rigid wheel and the flexible wheel is ≤0.

3.

10. A harmonic reducer with high load-bearing capacity and high rigidity according to claim 1, characterized in that: The flexible wheel (2) comprises a flexible wheel tooth portion (2b), and the rigid wheel (3) comprises a rigid wheel tooth portion (3b), and the flexible wheel tooth portion (2b) and the rigid wheel tooth portion (3b) form inter-tooth transmission.

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