An input mechanism and reducer for a cycloidal pinwheel reducer

Abstract

This application provides an input mechanism and a reducer for a cycloidal pinwheel reducer. The input mechanism includes an input shaft and a cylindrical pin. A first pin groove adapted to the cylindrical pin is formed on the side of the input shaft. One side of the cylindrical pin is located inside the first pin groove, and the other side of the cylindrical pin forms a protruding limiting structure outside the first pin groove. When the input mechanism is installed in the cycloidal pinwheel reducer, the protruding limiting structure connects to a second pin groove of the cycloidal pinwheel reducer. This application, by using a cylindrical pin to connect the input shaft and the eccentric mechanism, can retain a relatively closed, leak-proof structure while also meeting fatigue strength requirements.

Description

Technical Field

[0001] This application relates to the field of mechanical transmission technology, and in particular to an input mechanism and a reducer for a cycloidal pinwheel reducer. Background Technology

[0002] The cycloidal pinwheel reducer is a high-precision planetary transmission device that achieves speed reduction by driving a cycloidal wheel with a fixed pinwheel via an eccentric shaft. Its core component is a cycloidal wheel with short-amplitude epicycloidal teeth, which meshes simultaneously with the pinwheel, providing advantages such as a large reduction ratio, smooth transmission, low backlash, and high load-bearing capacity. The output mechanism converts the eccentric motion of the cycloidal wheel into fixed-axis rotation, transmitting high torque. This reducer features a compact structure, high rigidity, and long service life, and is widely used in precision transmission fields such as industrial robots, CNC machine tools, and automated equipment, making it a key component of modern intelligent manufacturing.

[0003] The input structure of a cycloidal pinwheel reducer needs to transmit torque to an eccentric wheel to drive the cycloidal wheel. Since the input shaft usually rotates at a high speed, it has high fatigue strength requirements. The matching structure between the input shaft and the eccentric wheel has become a major design challenge.

[0004] This section cites Chinese patent document CN104791425A, which discloses an input shaft connected to a corresponding eccentric structure via a key. However, traditional flat key pins often face the problem of stress concentration at the right angle of the key pin groove. For keyed shafts subjected to long-term rotation and cyclic stress, fatigue cracks typically begin to extend from this stress concentration point until the remaining structure can no longer withstand the applied torque, rapidly failing under shear stress and ultimately failing.

[0005] This section cites Chinese patent document CN118998268A, which discloses a method where the input shaft is directly connected to a corresponding eccentric structure, and the torque is directly transmitted to the corresponding eccentric structure via the double D-shaped structure of the input shaft. However, while this method is cheaper, under high-speed operation, the grease inside the reducer is prone to overflowing from the D-shaped opening at the end of the input shaft, causing grease loss from the reducer, resulting in environmental pollution and insufficient internal lubrication.

[0006] It is evident that the input structure of existing cycloidal pinwheel reducers is insufficient to meet the technical requirements for fatigue strength and oil leakage prevention.

[0007] It should be noted that the information in the background section above is only used to enhance the understanding of the background technology of this application, and therefore may include technical information that does not constitute technical information known or easily inferred by a person skilled in the art. Utility Model Content

[0008] In view of the above problems, this application is made to provide an input mechanism and reducer for a cycloidal pinwheel reducer that overcomes or at least partially solves the above problems, comprising: An input mechanism for a cycloidal pinwheel reducer includes: an input shaft and a cylindrical pin; The side of the input shaft is provided with a first pin groove that is adapted to the cylindrical pin. One side of the cylindrical pin is disposed inside the first pin groove, and the other side of the cylindrical pin forms a protruding limiting structure outside the first pin groove. When the input mechanism is installed on the cycloidal pinwheel reducer, the protruding limiting structure is connected to the second pin groove of the cycloidal pinwheel reducer.

[0009] Furthermore, the diameter of the cylindrical pin is 1-3mm; the length of the cylindrical pin is 10-30mm.

[0010] Furthermore, the input shaft has a hollow structure along its axial direction.

[0011] Furthermore, the diameter of the input shaft is greater than three times the sum of the diameter of the hollow structure and the diameter of the cylindrical pin.

[0012] Furthermore, the diameter of the hollow structure is 10-30 mm.

[0013] Furthermore, the cylindrical pins include at least two, and the first pin grooves include at least two; the cylindrical pins correspond one-to-one with the first pin grooves.

[0014] Furthermore, the cylindrical pins are arranged in a circumferential array on the outer side of the input shaft.

[0015] Furthermore, the two ends of the first pin groove are respectively set as spherical concave surfaces.

[0016] A cycloidal pinwheel reducer includes: an eccentric mechanism, a first bearing assembly, a cycloidal wheel mechanism, an output mechanism, a frame, and an input mechanism as described in any embodiment of this application; The second pin groove is provided in the eccentric mechanism; the cycloidal wheel mechanism is sleeved on the eccentric mechanism through the first bearing assembly; The frame includes a plurality of spaced-out outer roller needles; the output mechanism includes a plurality of spaced-out inner roller needles; the outer edge tooth profile of the cycloidal wheel mechanism meshes with the outer roller needles, and the inner roller needles are correspondingly inserted into the output hole of the cycloidal wheel mechanism; When the input shaft rotates, the input shaft drives the cycloidal wheel mechanism to move through the eccentric mechanism, and the cycloidal wheel mechanism drives the output mechanism to rotate through the inner needle roller.

[0017] Furthermore, the eccentric mechanism includes a first eccentric bushing and a second eccentric bushing; the second pin groove includes a first sub-pin groove and a second sub-pin groove. The first sub-pin groove is disposed in the first eccentric bushing; the second sub-pin groove is disposed in the second eccentric bushing; One side of the cylindrical pin is disposed inside the first pin groove, and the other side of the cylindrical pin forms a protruding limiting structure outside the first pin groove. The protruding limiting structure is connected to the first eccentric bushing through the first sub-pin groove; the protruding limiting structure is connected to the second eccentric bushing through the second sub-pin groove.

[0018] This application has the following advantages: In the embodiments of this application, addressing the issue that the existing input structure of cycloidal pinwheel reducers is insufficient to meet the technical requirements for fatigue strength and oil leakage prevention, this application provides a solution using a cylindrical pin to connect the input shaft and the eccentric mechanism of the reducer. Specifically, it includes: an input shaft and a cylindrical pin; a first pin groove adapted to the cylindrical pin is formed on the side of the input shaft; one side of the cylindrical pin is located inside the first pin groove, and the other side of the cylindrical pin forms a protruding limiting structure outside the first pin groove; when the input mechanism is installed in the cycloidal pinwheel reducer, the protruding limiting structure connects to the second pin groove of the cycloidal pinwheel reducer. This application, by using a cylindrical pin to connect the input shaft and the eccentric mechanism, can both retain a relatively closed oil leakage prevention structure and meet fatigue strength requirements. Attached Figure Description

[0019] To more clearly illustrate the technical solution of this application, the drawings used in the description of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the overall structure of the input mechanism for a cycloidal pinwheel reducer provided in one embodiment of this application; Figure 2 Yes Figure 1 A schematic diagram of the simulation results of finite element statics simulation of the input shaft; Figure 3 This is a schematic cross-sectional view of the combined structure of the input shaft, the first eccentric bushing, and the second eccentric bushing in one embodiment of this application; Figure 4 This is an exploded structural diagram of the input shaft, the first eccentric bushing, and the second eccentric bushing in one embodiment of this application; Figure 5 This is a schematic diagram of the first integral structure of a cycloidal pinwheel reducer provided in an embodiment of this application; Figure 6 This is a cross-sectional view of a cycloidal pinwheel reducer provided in one embodiment of this application; Figure 7 This is a schematic diagram of the second integral structure of a cycloidal pinwheel reducer provided in one embodiment of this application; Figure 8 yes Figure 7 A schematic diagram of the cross-sectional structure at section A.

[0021] The attached figures are labeled as follows: 1. Input mechanism; 11. Input shaft; 111. First pin groove; 12. Cylindrical pin; 13. Hollow structure; 2. Eccentric mechanism; 21. Second pin groove; 211. First sub-pin groove; 212. Second sub-pin groove; 22. First eccentric bushing; 23. Second eccentric bushing; 3. First bearing assembly; 4. Cycloidal wheel mechanism; 5. Output mechanism; 51. Inner needle roller; 6. Frame; 61. Outer needle roller; 7. Second bearing assembly; 8. Shim assembly; 9. Third bearing assembly. Detailed Implementation

[0022] To make the objectives, features, and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0023] Through analysis of existing technologies, the inventors discovered that the input structure of existing cycloidal pinwheel reducers is difficult to meet the technical requirements for fatigue strength and oil leakage prevention. The fundamental reason is that, on the one hand, using a key pin and eccentric structure at the input shaft can form a relatively closed structure that is not easy to leak oil, but it will lead to stress concentration; on the other hand, although adopting a D-type input shaft can relatively reduce stress concentration, in order to meet the assemblability of the D-type input shaft, the D-type structure needs to extend from the part that mates with the eccentric structure to the end of the input shaft, which makes it easy for grease to leak.

[0024] Based on the above analysis, one of the core technical concepts of this application is that by using a cylindrical pin to connect the input shaft and the eccentric mechanism, a relatively closed oil leakage prevention structure can be maintained, while also meeting fatigue strength requirements.

[0025] Reference Figure 1-4This application shows an embodiment of an input mechanism 1 for a cycloidal pinwheel reducer, comprising: an input shaft 11 and a cylindrical pin 12; The side of the input shaft 11 is provided with a first pin groove 111 that is adapted to the cylindrical pin 12; One side of the cylindrical pin 12 is disposed inside the first pin groove 111, and the other side of the cylindrical pin 12 forms a protruding limiting structure outside the first pin groove 111. When the input mechanism 1 is installed on the cycloidal pinwheel reducer, the protruding limiting structure is connected to the second pin groove 21 of the cycloidal pinwheel reducer.

[0026] In the embodiments of this application, addressing the issue that the existing input structure of cycloidal pinwheel reducers is insufficient to meet the technical requirements for fatigue strength and oil leakage prevention, this application provides a solution using a cylindrical pin 12 to connect the input shaft 11 and the eccentric mechanism 2 of the reducer. Specifically, the solution includes: an input shaft 11 and a cylindrical pin 12; a first pin groove 111 adapted to the cylindrical pin 12 is provided on the side of the input shaft 11; one side of the cylindrical pin 12 is located inside the first pin groove 111, and the other side of the cylindrical pin 12 forms a protruding limiting structure outside the first pin groove 111; when the input mechanism 1 is installed in the cycloidal pinwheel reducer, the protruding limiting structure connects to the second pin groove 21 of the cycloidal pinwheel reducer. This application, by using a cylindrical pin 12 to connect the input shaft 11 and the eccentric mechanism 2, can both retain a relatively closed oil leakage prevention structure and meet fatigue strength requirements.

[0027] The input mechanism 1 and the reducer for a cycloidal pinwheel reducer will now be further described in this exemplary embodiment.

[0028] In one embodiment of this application, the diameter of the cylindrical pin 12 is 1-3 mm; the length of the cylindrical pin 12 is 10-30 mm.

[0029] It should be noted that by reasonably setting the diameter and length of the cylindrical pin 12, it is possible to avoid occupying too much space of the input shaft 11 and ensure the output of the torque of the input shaft 11.

[0030] In one embodiment of this application, the input shaft 11 has a hollow structure 13 along the axial direction.

[0031] It should be noted that, compared with the shaft key structure, by using the cylindrical pin 12 as the transmission structure between the input shaft 11 and the eccentric mechanism 2, the maximum equivalent stress at the joint surface between the cylindrical pin 12 and the input shaft 11 is smaller. Therefore, the groove depth on the input shaft 11 is lower and stress concentration is less likely to occur. While ensuring structural strength, the diameter of the hollow structure 13 inside the input shaft 11 is maximized.

[0032] The hollow structure 13 can be used to reduce the weight of the input shaft 11. The hollow structure 13 can be cylindrical. When the reducer is used as the transmission structure of the robot, the hollow structure 13 of the input shaft 11 can also be used to pass through the robot's electrical control cables, which facilitates wiring.

[0033] In a specific implementation, refer to Figure 2 The torque of the input shaft 11 is transmitted to two eccentric bushings via two steel cylindrical pins 12 with a diameter of 1.5 mm. The outer side of the eccentric shaft is connected to the inner ring of the thin-walled bearing, and the outer ring of the thin-walled bearing is connected to the cycloidal wheel, driving the cycloidal wheel to perform eccentric cycloidal motion. Finite element static simulation of the input shaft 11 using ANSYS shows that when subjected to the peak torque (4.3 Nm) of the matching frameless torque motor, the maximum equivalent stress at the joint surface between the cylindrical pins 12 and the input shaft 11 is only 128.26 MPa. This value is much smaller than the fatigue strength (290 MPa) of the aluminum alloy material (7075) of the input shaft 11 under 3E10^6 alternating loads.

[0034] In one embodiment of this application, the diameter of the input shaft 11 is greater than three times the sum of the diameter of the hollow structure 13 and the diameter of the cylindrical pin 12.

[0035] It should be noted that by reasonably setting the diameter of the input shaft 11, the structural strength of the input shaft 11 can be guaranteed when the hollow structure 13 is provided, thereby improving the service life of the input mechanism 1. The calculation formula for the outer diameter of the input shaft 11 (corresponding to the circumference in contact with the eccentric mechanism 2) is as follows:

[0036] in, The outer diameter of input shaft 11 The diameter of cylindrical pin 12, The diameter of the hollow part of the input shaft 11.

[0037] In one embodiment of this application, the diameter of the hollow structure 13 is 10-30 mm.

[0038] It should be noted that when the reducer is used as the transmission structure of the robot, properly setting the size of the hollow structure 13 of the input shaft 11 can facilitate the arrangement of the robot's electrical control cables. The diameter range of the cylindrical pin 12 is constrained by the aforementioned range of the hollow diameter of the input shaft 11.

[0039] In one embodiment of this application, the cylindrical pin 12 includes at least two, and the first pin groove 111 includes at least two; the cylindrical pin 12 corresponds one-to-one with the first pin groove 111.

[0040] As an example, the cylindrical pin 12 may include only one.

[0041] As an example, the cylindrical pin 12 may also include two, with the two cylindrical pins 12 respectively disposed on opposite sides of the input shaft 11.

[0042] As an example, the cylindrical pins 12 may also include three or more, with the plurality of cylindrical pins 12 arranged in an array along the circumferential direction of the input shaft 11.

[0043] In one embodiment of this application, the cylindrical pins 12 are arranged in a circumferential array on the outer side of the input shaft 11.

[0044] It should be noted that the cylindrical pins 12 arranged in a circular array can make the torque output of the input shaft 11 more uniform, thereby improving the service life of the input shaft 11.

[0045] In one embodiment of this application, the two ends of the first pin groove 111 are respectively set as spherical concave surfaces.

[0046] It should be noted that the spherical concave surface of the first pin groove 111 makes the installation of the cylindrical pin 12 more convenient, and the cylindrical pin 12 can be axially limited by the gasket assembly 8 set at both ends of the cylindrical pin 12.

[0047] Reference Figure 5-8 This application illustrates a cycloidal pinwheel reducer according to an embodiment of the present application, comprising: an eccentric mechanism 2, a first bearing assembly 3, a cycloidal wheel mechanism 4, an output mechanism 5, a frame 6, and an input mechanism 1 as described in any embodiment of the present application; The second pin groove 21 is provided in the eccentric mechanism 2; the cycloidal wheel mechanism 4 is sleeved on the eccentric mechanism 2 through the first bearing assembly 3; The frame 6 includes a plurality of spaced-out outer roller needles 61; the output mechanism 5 includes a plurality of spaced-out inner roller needles 51; the outer edge tooth profile of the cycloidal wheel mechanism 4 meshes with the outer roller needles 61, and the inner roller needles 51 are correspondingly inserted through the output hole of the cycloidal wheel mechanism 4. When the input shaft 11 rotates, the input shaft 11 drives the cycloidal wheel mechanism 4 to move through the eccentric mechanism 2, and the cycloidal wheel mechanism 4 drives the output mechanism 5 to rotate through the inner needle roller 51.

[0048] It should be noted that the outer needle rollers 61 are arranged in a circumferential array on the inner side of the frame 6; the inner needle rollers 51 are arranged in a circumferential array on the output mechanism 5 and pass through the output hole of the cycloidal wheel mechanism 4. The input mechanism 1 can also serve as the input structure of other mechanical transmission devices.

[0049] In one embodiment of this application, the eccentric mechanism 2 includes a first eccentric bushing 22 and a second eccentric bushing 23; the second pin groove 21 includes a first sub-pin groove 211 and a second sub-pin groove 212. The first sub-pin groove 211 is disposed in the first eccentric bushing 22; the second sub-pin groove 212 is disposed in the second eccentric bushing 23; One side of the cylindrical pin 12 is disposed inside the first pin groove 111, and the other side of the cylindrical pin 12 forms a protruding limiting structure outside the first pin groove 111. The protruding limiting structure is connected to the first eccentric bushing 22 through the first sub-pin groove 211; the protruding limiting structure is connected to the second eccentric bushing 23 through the second sub-pin groove 212.

[0050] It should be noted that by providing pin grooves in the first eccentric bushing 22 and the second eccentric bushing 23 respectively, the cylindrical pin 12 can simultaneously transmit the torque of the input shaft 11 to the first eccentric bushing 22 and the second eccentric bushing 23, and then transmit it to the cycloidal wheel mechanism 4 for eccentric motion.

[0051] In one specific embodiment of this application, it further includes: a second bearing assembly 7 and a gasket assembly 8; The output mechanism 5 is sleeved on the input shaft 11 via the second bearing assembly 7; The gasket assembly 8 is sleeved on the input mechanism 1, and the gasket assembly 8 is connected between the first bearing assembly 3 and the second bearing assembly 7.

[0052] It should be noted that the second bearing assembly 7 can be used to maintain the radial distance between the input shaft 11 and the output mechanism 5.

[0053] In one specific embodiment of this application, it further includes: a third bearing assembly 9; the frame 6 is sleeved on the output mechanism 5 via the third bearing assembly 9.

[0054] It should be noted that the third bearing assembly 9 can be used to maintain the radial distance between the output mechanism 5 and the frame 6.

[0055] In the above embodiments of this application, the torque from the input shaft 11 is transmitted by replacing the traditional flat key pin or D-type shaft with a cylindrical pin 12, thereby reducing the defects of stress concentration at the root of the traditional flat key pin groove, while reducing the volume occupation and increasing the diameter of the hollow wiring hole in the reducer.

[0056] Although preferred embodiments of the present application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the embodiments of the present application.

[0057] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or terminal device. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or terminal device that includes said element.

[0058] The above provides a detailed description of the input mechanism and reducer for a cycloidal pinwheel reducer provided in this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, those skilled in the art will have changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. An input mechanism for a cycloidal pinwheel reducer, characterized in that, include: Input shaft and cylindrical pin; The side of the input shaft is provided with a first pin groove that is adapted to the cylindrical pin. One side of the cylindrical pin is disposed inside the first pin groove, and the other side of the cylindrical pin forms a protruding limiting structure outside the first pin groove. When the input mechanism is installed on the cycloidal pinwheel reducer, the protruding limiting structure is connected to the second pin groove of the cycloidal pinwheel reducer.

2. The input mechanism according to claim 1, characterized in that, The diameter of the cylindrical pin is 1-3mm; the length of the cylindrical pin is 10-30mm.

3. The input mechanism according to claim 1, characterized in that, The input shaft has a hollow structure along its axial direction.

4. The input mechanism according to claim 3, characterized in that, The diameter of the input shaft is greater than three times the sum of the diameter of the hollow structure and the diameter of the cylindrical pin.

5. The input mechanism according to claim 3, characterized in that, The diameter of the hollow structure is 10-30 mm.

6. The input mechanism according to claim 1, characterized in that, The cylindrical pins include at least two, and the first pin grooves include at least two; the cylindrical pins correspond one-to-one with the first pin grooves.

7. The input mechanism according to claim 6, characterized in that, The cylindrical pins are arranged in a circumferential array on the outside of the input shaft.

8. The input mechanism according to claim 1, characterized in that, The two ends of the first pin groove are respectively set as spherical concave surfaces.

9. A cycloidal pinwheel reducer, characterized in that, include: An eccentric mechanism, a first bearing assembly, a cycloidal wheel mechanism, an output mechanism, a frame, and an input mechanism as described in any one of claims 1-8; The second pin groove is provided in the eccentric mechanism; the cycloidal wheel mechanism is sleeved on the eccentric mechanism through the first bearing assembly; The frame includes a plurality of spaced-out outer roller needles; the output mechanism includes a plurality of spaced-out inner roller needles; the outer edge tooth profile of the cycloidal wheel mechanism meshes with the outer roller needles, and the inner roller needles are correspondingly inserted into the output hole of the cycloidal wheel mechanism; When the input shaft rotates, the input shaft drives the cycloidal wheel mechanism to move through the eccentric mechanism, and the cycloidal wheel mechanism drives the output mechanism to rotate through the inner needle roller.

10. The reducer according to claim 9, characterized in that, The eccentric mechanism includes a first eccentric bushing and a second eccentric bushing; the second pin groove includes a first sub-pin groove and a second sub-pin groove. The first sub-pin groove is disposed in the first eccentric bushing; the second sub-pin groove is disposed in the second eccentric bushing; One side of the cylindrical pin is disposed inside the first pin groove, and the other side of the cylindrical pin forms a protruding limiting structure outside the first pin groove. The protruding limiting structure is connected to the first eccentric bushing through the first sub-pin groove; the protruding limiting structure is connected to the second eccentric bushing through the second sub-pin groove.

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