An RV reducer for robots

Abstract

This invention provides an RV reducer for robots, comprising: an input shaft, a planetary gear mechanism, a crankshaft, a pin tooth housing, a housing, an output disk, and a preload adjustment mechanism. The planetary gear mechanism is located at the output end of the input shaft, and the input end of the input shaft is connected to a drive motor. The crankshaft is driven to rotate by the planetary gear mechanism and has eccentric portions on both sides. Cycloidal wheels are symmetrically arranged on the two eccentric portions. The outer circumference of the cycloidal wheels is provided with bidirectionally modified cycloidal teeth. The pin tooth housing is located inside the housing and has several rings of pin teeth on its inner circumference. This RV reducer significantly reduces the peak contact stress by optimizing the cycloidal wheel tooth profile modification parameters (0.02-0.04mm bidirectional modification) and the non-uniform distribution design of the pin teeth; it uses a preload adjustment mechanism to dynamically compensate for the meshing clearance, keeping the backlash stable within 1 arc minute; and the planetary gears adopt a 1:3 high reduction ratio design to achieve a compact structure.

Description

Technical Field

[0001] This invention relates to the field of robot joint technology, and more particularly to an RV reducer for robots. Background Technology

[0002] The RV reducer (also known as the planetary cycloidal pinwheel reducer) mainly consists of a single-stage planetary gear drive and a two-stage cycloidal pinwheel drive. It is a new type of cycloidal pinwheel planetary transmission reducer. RV reducers are mostly used in the joint positions of industrial robots, where they typically bear large loads during operation. This places high demands on the rigidity, impact resistance, wear resistance, and lifespan of the RV reducer.

[0003] Currently, the RV reducers commonly found on the market generally have the following problems:

[0004] 1. The tooth profile of traditional cycloidal wheels is not optimized, which easily leads to stress concentration and insufficient lifespan;

[0005] 2. The meshing clearance between the needle teeth and the cycloidal teeth is not adjustable, and the backlash increases after long-term wear;

[0006] 3. The unreasonable design of the planetary gear transmission ratio affects the miniaturization of the reducer;

[0007] 4. Large coaxiality error of input and output axes affects the robot's motion accuracy.

[0008] Therefore, it is necessary to design a high-precision RV reducer with dynamically adjustable meshing clearance and low vibration. Summary of the Invention

[0009] To address the technical deficiencies in the background technology, this invention proposes an RV reducer for robots, which solves the aforementioned technical problems and meets practical needs. The specific technical solution is as follows:

[0010] An RV reducer for robots includes: an input shaft, a planetary gear mechanism, a crankshaft, a pin tooth housing, a housing, an output disk, and a preload adjustment mechanism. The planetary gear mechanism is located at the output end of the input shaft, and the input end of the input shaft is connected to a drive motor. The crankshaft is driven to rotate by the planetary gear mechanism and has eccentric portions on both sides. Cycloidal wheels are symmetrically arranged on the two eccentric portions. The outer circumference of the cycloidal wheels is provided with bidirectionally modified cycloidal teeth. The pin tooth housing is located inside the housing and has several rings of pin teeth on its inner circumference. The output disk is connected to the cycloidal wheels via an involute spline. The preload adjustment mechanism includes a butterfly spring assembly and an adjusting bolt for adjusting the meshing clearance between the pin teeth and the cycloidal teeth. The modification amount of the cycloidal teeth satisfies: 0.02mm ≤ ≤ 0.04mm, and the modification direction includes root modification and tip modification.

[0011] Furthermore, the ratio of the number of teeth between the sun gear and the planet gears in the planetary gear mechanism is 1:3, and the module is 0.6mm-1mm.

[0012] Furthermore, it also includes a magnetohydrodynamic sealing ring, which is disposed in the gap between the output disk and the housing.

[0013] Furthermore, the input shaft has a hollow structure with a keyway on its inner wall for cables or air ducts to pass through the robot joint.

[0014] Furthermore, the tooth tip modification amount &1 and tooth root modification amount &2 of the cycloidal tooth satisfy: &1 / &2=1.2-1.5.

[0015] Furthermore, the shell is made of carbon fiber reinforced aluminum alloy, with a carbon fiber volume fraction of 15%-25%.

[0016] Furthermore, it also includes temperature sensors and vibration sensors, which are embedded in the inner wall of the pin tooth housing for real-time monitoring of the reducer's operating status.

[0017] Furthermore, the distribution density of the needle teeth increases by 15-25% in the region of maximum meshing stress of the cycloidal wheel, while the remaining regions are equidistantly distributed.

[0018] Furthermore, the diameter of the needle teeth is 0.05-0.1 mm larger in the region of maximum stress than in the other regions.

[0019] Furthermore, the magnetic fluid material of the magnetic fluid sealing ring is Fe3O4-based nanofluid with a magnetic induction intensity of 0.3-0.5T.

[0020] Compared with the prior art, the RV reducer for robots provided by the present invention has the following beneficial effects:

[0021] This invention discloses an RV reducer for robots. By optimizing the cycloidal gear tooth profile parameters (0.02-0.04mm bidirectional profile modification) and the non-uniform distribution of the needle teeth, it significantly reduces peak contact stress. A preload adjustment mechanism dynamically compensates for meshing clearance, stabilizing backlash within 1 arc minute. The planetary gears employ a 1:3 high reduction ratio design, achieving a compact structure. This reducer combines high precision (coaxiality error ≤0.008mm), long lifespan (≥15,000 hours), and low vibration characteristics, making it suitable for six-axis industrial robot joints. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of an RV reducer for a robot according to the present invention.

[0023] Figure 2 This is a schematic diagram of the internal structure of an RV reducer for robots according to the present invention.

[0024] Figure 3 This is a schematic diagram of the shell structure in this invention.

[0025] Figure 4 This is a schematic diagram of the connection between the crankshaft and the planetary gear mechanism in this invention.

[0026] Figure 5 This is a schematic diagram of the bottom structure of an RV reducer for a robot according to the present invention.

[0027] Among them, 1. Input shaft, 2. Planetary gear mechanism, 3. Crankshaft, 4. Needle tooth housing, 5. Housing, 6. Output disc, 7. Preload adjustment mechanism, 8. Eccentric part, 9. Cycloidal wheel, 10. Cycloidal tooth, 11. Involute spline, 12. Sun gear, 13. Planet gear, 14. Magnetohydrodynamic sealing ring, 15. Keyway. Detailed Implementation

[0028] In the description of this invention, it should be understood that the terms "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "middle," and "inner," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, it should be noted that unless otherwise explicitly specified and limited, the terms "installed," "connected," and "joined" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention through specific circumstances.

[0029] The embodiments of the present invention will be described below with reference to the accompanying drawings and related examples. The embodiments of the present invention are not limited to the following examples, and the present invention relates to the relevant necessary components in this technical field, which should be regarded as well-known technology in this technical field and can be known and mastered by those skilled in this technical field.

[0030] See Figure 1-5An RV reducer for robots includes: an input shaft 1, a planetary gear mechanism 2, a crankshaft 3, a pin tooth housing 4, a housing 5, an output disk 6, and a preload adjustment mechanism 7. The planetary gear mechanism 2 is located at the output end of the input shaft 1, and the input end of the input shaft 1 is connected to a drive motor. The crankshaft 3 is driven to rotate by the planetary gear mechanism 2 and has eccentric portions 8 on both sides. Cycloidal wheels 8 are symmetrically arranged on the two eccentric portions 8. Cycloidal wheels 8 have bidirectionally modified cycloidal teeth 10 on their outer circumference. The pin tooth housing 4 is located inside the housing 5 and has several rings of pin teeth on its inner circumference. The output disk 6 is connected to the cycloidal wheels 8 through an involute spline 11. The preload adjustment mechanism 7 includes a butterfly spring assembly and an adjusting bolt, used to adjust the meshing clearance between the pin teeth and the cycloidal teeth 10. Existing technologies mostly use shims for static adjustment, which cannot dynamically adapt to wear. Dynamic compensation of the meshing clearance can be achieved through a butterfly spring assembly and adjusting bolts, with backlash stably controlled within ≤1 arc minute, compared to 2-3 arc minutes after wear in traditional fixed clearance designs. Preload can be adjusted without disassembly, reducing maintenance costs by 60%. The modification amount of the cycloidal tooth 10 satisfies: 0.02mm ≤ & ≤ 0.04mm, with modification directions including tooth root modification and tooth tip modification. By employing bidirectional modification at both the tooth tip and root, and limiting the modification amount range, stress concentration on the tooth surface can be reduced, extending the service life to 15,000 hours, reducing meshing impact noise, and lowering vibration amplitude by 42%.

[0031] In one embodiment of the present invention, the ratio of the number of teeth between the sun gear 12 and the planet gears 13 in the planetary gear mechanism 2 is 1:3, and the module is 0.6mm-1mm. Under the same volume, the reduction ratio is increased to 30-50:1, resulting in a compact structure suitable for miniaturized robot joints.

[0032] In one embodiment of the present invention, a magnetohydrodynamic (MHD) sealing ring 14 is further included, which is disposed at the gap between the output disk 6 and the housing 5. Traditional rubber seals last approximately 2-3 years, while the sealing life is extended to over 5 years after using the MHD sealing ring 14. Furthermore, it is heat-resistant and suitable for robots operating in extreme environments.

[0033] In one embodiment of the present invention, the input shaft 1 is a hollow structure with a keyway 15 on its inner wall for cables or air ducts to pass through the robot joint. The hollow input shaft 1 reduces the wiring space of the robot joint by 40%, making it suitable for the narrow joint cavities of collaborative robots.

[0034] In one embodiment of the present invention, the tooth tip modification amount &1 and the tooth root modification amount &2 of the cycloidal tooth 10 satisfy: &1 / &2=1.2-1.5.

[0035] In one embodiment of the present invention, the housing 5 is made of carbon fiber reinforced aluminum alloy, with a carbon fiber volume fraction of 15%-25%. This combination of lightweight and high rigidity reduces the inertia of the robot joints.

[0036] In one embodiment of the present invention, a temperature sensor and a vibration sensor are further included, embedded in the inner wall of the pin tooth housing 4, for real-time monitoring of the reducer's operating status. The temperature sensor and vibration sensor enable intelligent monitoring and predictive surveillance.

[0037] In one embodiment of the present invention, the distribution density of the needle teeth increases by 15-25% in the region of maximum meshing stress of the cycloidal wheel 8, and is equidistantly distributed in the remaining regions.

[0038] In one embodiment of the present invention, the diameter of the needle teeth is 0.05-0.1 mm larger in the region of maximum stress than in the other regions.

[0039] In one embodiment of the present invention, the magnetic fluid material of the magnetic fluid sealing ring 14 is Fe3O4-based nanofluid with a magnetic induction intensity of 0.3-0.5T.

[0040] This invention discloses an RV reducer for robots. Through optimized bidirectional profile modification parameters (0.02-0.04 mm) of the cycloidal gear 8 and a non-uniform needle tooth distribution design, it significantly reduces peak contact stress. A preload adjustment mechanism 7 dynamically compensates for meshing clearance, stabilizing backlash within 1 arc minute. The planetary gears employ a 1:3 high reduction ratio design, achieving a compact structure. This reducer combines high precision (coaxiality error ≤0.008 mm), long lifespan (≥15,000 hours), and low vibration characteristics, making it suitable for six-axis industrial robot joints.

[0041] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An RV reducer for robots, characterized in that, include: The system comprises an input shaft (1), a planetary gear mechanism (2), a crankshaft (3), a pin tooth housing (4), a housing (5), an output disc (6), and a preload adjustment mechanism (7). The planetary gear mechanism (2) is located at the output end of the input shaft (1), and the input end of the input shaft (1) is connected to a drive motor. The crankshaft (3) is driven to rotate by the planetary gear mechanism (2) and has eccentric parts (8) on both sides. Cycloidal wheels are symmetrically arranged on the two eccentric parts (8). Cycloidal wheels have bidirectionally modified cycloidal teeth (10) on their outer circumference. The pin tooth housing (4) is located inside the housing (5) and has several rings of pin teeth on its inner circumference. The output disc (6) is connected to the cycloidal wheels via an involute spline (11). The preload adjustment mechanism (7) includes a butterfly spring assembly and an adjusting bolt, used to adjust the meshing clearance between the pin teeth and the cycloidal teeth (10). The modification amount of the cycloidal teeth (10) satisfies the following conditions: The shaping direction includes root shaping and tip shaping; The tooth tip modification amount &1 and tooth root modification amount &2 of the cycloidal tooth (10) satisfy: &1 / &2=1.2-1.5; The distribution density of the needle teeth increases by 15-25% in the region of maximum meshing stress of the cycloidal wheel, and is equidistant in the remaining regions. The diameter of the needle teeth is 0.05-0.1 mm larger in the region of maximum stress than in other regions.

2. The RV reducer for a robot according to claim 1, characterized in that, The ratio of the number of teeth of the sun gear (12) and the planet gear (13) in the planetary gear mechanism (2) is 1:3, and the module is 0.6mm-1mm.

3. The RV reducer for a robot according to claim 1, characterized in that, It also includes a magnetic fluid sealing ring (14), which is disposed in the gap between the output disk (6) and the housing (5).

4. An RV reducer for a robot according to claim 1, characterized in that, The input shaft (1) is a hollow structure with a keyway (15) on its inner wall for cables or air pipes to pass through the robot joint.

5. An RV reducer for a robot according to claim 1, characterized in that, The shell (5) is made of carbon fiber reinforced aluminum alloy material, with a carbon fiber volume fraction of 15%-25%.

6. An RV reducer for a robot according to claim 1, characterized in that, It also includes a temperature sensor and a vibration sensor, which are embedded in the inner wall of the needle tooth housing (4) for real-time monitoring of the reducer's operating status.

7. An RV reducer for a robot according to claim 3, characterized in that, The magnetic fluid material of the magnetic fluid sealing ring (14) is Fe3O4-based nanofluid with a magnetic induction intensity of 0.3-0.5T.

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