A cycloidal speed reducer

Abstract

This application provides a cycloidal pinwheel reducer. An eccentric mechanism is sleeved on the input mechanism, and the cycloidal wheel mechanism is sleeved on the eccentric mechanism via a first bearing assembly. The frame includes a plurality of spaced-apart outer pinwheels; the output mechanism includes a plurality of spaced-apart inner pinwheels; each inner pinwheel has a corresponding first bushing; and each outer pinwheel has a corresponding second bushing. The diameter ratio of the outer pinwheels to the inner pinwheels is 1:2 to 2:1, and the number of inner pinwheels is 40% to 60% of the number of outer pinwheels. The outer edge tooth profile of the cycloidal wheel mechanism meshes with the outer pinwheels, and the inner pinwheels and the first bushings pass through the output holes of the cycloidal wheel mechanism. By setting relatively close diameters for the inner and outer pinwheels and a specific ratio of their numbers, this application can reduce bushing wear, lower the return torque, balance the service life of the inner and outer pinwheels, and reduce production and maintenance costs.

Description

Technical Field

[0001] This application relates to the field of mechanical transmission technology, and in particular to 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] In cycloidal pinwheel reducers, the main friction losses include four types: bearing loss, outer needle roller bushing loss, inner needle roller bushing loss, and agitation loss. Among these, needle roller bushing loss accounts for a significant portion of the losses in cycloidal pinwheel reducers. Therefore, reducing needle roller bushing loss to improve efficiency has become a design challenge for cycloidal pinwheel reducers.

[0004] Meanwhile, in cycloidal pinwheel reducers, the needle rollers fail in two ways: bending fatigue failure and surface contact fatigue failure. The smaller the diameter of the needle roller, the greater the maximum bending and contact stress, making it more prone to failure and affecting lifespan. Conversely, the larger the diameter of the needle roller, the higher the efficiency loss. Existing cycloidal pinwheel reducers typically use large-diameter internal needle rollers to improve load capacity, thus sacrificing friction efficiency.

[0005] It is evident that the existing design of the number of needle rollers and the inner diameter of cycloidal pinwheel reducers cannot simultaneously meet the technical requirements of efficiency and lifespan.

[0006] 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

[0007] In view of the above problems, this application is made in order to provide a cycloidal pinwheel reducer that overcomes or at least partially solves the above problems.

[0008] This application provides a cycloidal pinwheel reducer, comprising: an input mechanism, an eccentric mechanism, a first bearing assembly, a cycloidal wheel mechanism, an output mechanism, and a frame; The eccentric mechanism is sleeved on the input mechanism, and the cycloidal wheel mechanism is sleeved on the eccentric mechanism through the first bearing assembly; The frame includes a plurality of spaced-apart outer needle rollers; the output mechanism includes a plurality of spaced-apart inner needle rollers; each inner needle roller is provided with a corresponding first bushing; each outer needle roller is provided with a corresponding second bushing; wherein the diameter ratio of the outer needle rollers to the inner needle rollers is 1:2-2:1, and the number of inner needle rollers is 40%-60% of the number of outer needle rollers; The outer edge tooth profile of the cycloidal wheel mechanism meshes with the outer roller needle, and the inner roller needle and the first bushing are respectively inserted through the output hole of the cycloidal wheel mechanism; When the input mechanism rotates, it drives the cycloidal wheel mechanism to perform eccentric motion through the eccentric mechanism, and the cycloidal wheel mechanism drives the output mechanism to rotate through the inner needle roller.

[0009] Furthermore, the diameter ratio of the outer needle roller to the inner needle roller is 1:2, 1:1, or 2:1; the number of inner needle rollers is 40%, 50%, or 60% of the number of outer needle rollers.

[0010] Furthermore, the input mechanism includes an input shaft and a cylindrical pin; The eccentric mechanism is sleeved on the input shaft by the cylindrical pin.

[0011] Furthermore, the eccentric mechanism includes a first eccentric bushing and a second eccentric bushing; The first eccentric bushing is provided with a first eccentric wheel; the second eccentric bushing is provided with a second eccentric wheel; the first eccentric bushing and the second eccentric bushing abut against each other along the axial direction, and a third eccentric wheel is formed at the abutment portion; The cycloidal wheel mechanism is sleeved on the first eccentric wheel, the second eccentric wheel, and the third eccentric wheel via the first bearing assembly.

[0012] Furthermore, the first bearing assembly includes: a first eccentric bearing, a second eccentric bearing, and a third eccentric bearing; The first eccentric bearing is sleeved on the first eccentric wheel; the second eccentric bearing is sleeved on the second eccentric wheel; and the third eccentric bearing is sleeved on the third eccentric wheel.

[0013] Furthermore, the cycloidal wheel mechanism includes a first cycloidal wheel, a second cycloidal wheel, and a third cycloidal wheel; The first cycloidal wheel is sleeved on the first eccentric bearing; the second cycloidal wheel is sleeved on the second eccentric bearing; and the third cycloidal wheel is sleeved on the third eccentric bearing.

[0014] Furthermore, it also includes: a second bearing assembly and a gasket assembly; The output mechanism is sleeved on the input shaft via the second bearing assembly; The gasket assembly is sleeved on the input mechanism, the gasket assembly is connected between the first bearing assembly and the second bearing assembly, and the gasket assembly is disposed in the slit channel formed by the eccentric mechanism, the first bearing assembly, the input mechanism and the second bearing assembly.

[0015] Furthermore, the gasket assembly includes a first gasket; the first gasket is sleeved on the eccentric mechanism, and one end face of the first gasket abuts against the first bearing assembly; wherein, the outer diameter of the first gasket is greater than the center diameter of the corresponding bearing in the first bearing assembly, and smaller than the inner diameter of the outer ring of the corresponding bearing.

[0016] Furthermore, the gasket assembly also includes a second gasket; the second gasket is sleeved on the input shaft, and one end face of the second gasket abuts against the eccentric mechanism, the end of the cylindrical pin, and the other end face of the first gasket.

[0017] Furthermore, the gasket assembly also includes a third gasket; the third gasket is sleeved on the input shaft, one end face of the third gasket abuts against the other end face of the second gasket, and the other end face of the third gasket abuts against the second bearing assembly; wherein, the outer diameter of the third gasket is larger than the center diameter of the corresponding bearing in the second bearing assembly, and smaller than the inner diameter of the outer ring of the corresponding bearing.

[0018] This application has the following advantages: In the embodiments of this application, addressing the difficulty in simultaneously meeting the technical requirements of efficiency and lifespan in the design of the number and inner diameter of the inner and outer needle rollers in existing cycloidal pinwheel reducers, this application provides a solution for rationally setting the ratio of inner and outer needle roller diameters and quantities. Specifically, a cycloidal pinwheel reducer includes: an input mechanism, an eccentric mechanism, a first bearing assembly, a cycloidal wheel mechanism, an output mechanism, and a frame; the eccentric mechanism is sleeved on the input mechanism, and the cycloidal wheel mechanism is sleeved on the eccentric mechanism via the first bearing assembly; the frame includes a plurality of spaced-apart outer needle rollers; the output mechanism includes a plurality of spaced-apart outer needle rollers... The device comprises an inner needle roller; an inner needle roller with a corresponding first bushing; and an outer needle roller with a corresponding second bushing. The diameter ratio of the outer needle roller to the inner needle roller is 1:2-2:1, and the number of inner needle rollers is 40%-60% of the number of outer needle rollers. The outer edge tooth profile of the cycloidal wheel mechanism meshes with the outer needle rollers, and the inner needle rollers and the first bushing are respectively inserted into the output hole of the cycloidal wheel mechanism. When the input mechanism rotates, the input mechanism drives the cycloidal wheel mechanism to perform eccentric motion through the eccentric mechanism, and the cycloidal wheel mechanism drives the output mechanism to rotate through the inner needle rollers. This application, by setting relatively close diameters for the inner and outer needle rollers and a specific ratio of their numbers, can reduce bushing wear, decrease return torque, balance the service life of the inner and outer needle rollers, and reduce production and maintenance costs. 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 It is a stacked area diagram of the efficiency losses of each component of the reducer; Figure 2 This is a schematic diagram of a high length-to-diameter ratio bushing bearing structure equivalent to a bushing needle roller structure. Figure 3 This is a schematic diagram of the first integral structure of a cycloidal pinwheel reducer provided in an embodiment of this application; Figure 4 This is a cross-sectional view of a cycloidal pinwheel reducer provided in one embodiment of this application; Figure 5 This is a graph showing the relationship between the wear and input speed of bearings with different diameter bushings under the same conditions; Figure 6 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 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 Schematic diagram of the cross-sectional structure at section A in the middle; Figure 9 This is a schematic diagram of the third integral structure of a cycloidal pinwheel reducer provided in one embodiment of this application; Figure 10 yes Figure 9 A schematic diagram of the cross-sectional structure at section B; wherein, there are 20 outer rollers and 10 inner rollers; Figure 11 The difference lies in the number of external and internal needle rollers. Figure 10 A cross-sectional view of a cycloidal pinwheel reducer; wherein the number of outer needle rollers is 24 and the number of inner needle rollers is 12; Figure 12 The difference lies in the number of external and internal needle rollers. Figure 10 A cross-sectional view of a cycloidal pinwheel reducer; wherein the number of outer needle rollers is 32 and the number of inner needle rollers is 16; Figure 13 This is a schematic diagram of the combined structure of the eccentric mechanism and the cycloidal wheel mechanism exploded along the axial direction in one embodiment of this application; Figure 14 yes Figure 13 Schematic diagram of the cross-sectional structure at section C; Figure 15 yes Figure 4 A magnified schematic diagram of part D in the middle section.

[0021] The attached figures are labeled as follows: 1. Input mechanism; 11. Input shaft; 112. Annular connector; 12. Cylindrical pin; 2. Eccentric mechanism; 21. First eccentric bushing; 211. First eccentric wheel; 22. Second eccentric bushing; 221. Second eccentric wheel; 23. Third eccentric wheel; 3. First bearing assembly; 31. First eccentric bearing; 32. Second eccentric bearing; 33. Third eccentric bearing; 4. Cycloidal wheel mechanism; 41. First cycloidal wheel; 42. Second cycloidal wheel; 43. Third cycloidal wheel; 44. Output hole; 5. Output Mechanism; 51, Inner needle roller; 511, First bushing; 52, First inner housing; 53, Second inner housing; 6, Frame; 61, Outer needle roller; 611, Second bushing; 62, First outer housing; 63, Second outer housing; 7, Second bearing assembly; 71, First input bearing; 72, Second input bearing; 8, Shim assembly; 81, First shim; 82, Second shim; 83, Third shim; 84, Slit channel; 9, Third bearing assembly; 91, First output bearing; 92, Second output bearing. 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] The inventors discovered through analysis of existing technology that existing cycloidal pinwheel reducers achieve speed reduction transmission through bushing needle rollers. Specifically, the eccentric cycloidal motion of the cycloidal wheel mechanism is achieved through the outer needle rollers, and the output torque of the cycloidal wheel mechanism is transmitted to the output mechanism through the inner needle rollers. On the one hand, for existing miniature cycloidal pinwheel reducers using bushing needle rollers, through inertia free rotation experiments and combined with elastohydrodynamic friction models of each component, the following can be obtained: Figure 1 The diagram shows the stacked area of ​​efficiency losses for each component of the reducer. It can be seen that within the servo motor's operating speed range (0-6000 rpm), internal needle roller loss is the largest source of loss in the cycloidal pinwheel reducer, accounting for more than 50% of the total loss at times. Within the DC brushless motor's operating speed range (0-7500 rpm), internal needle roller loss remains the second largest contributor at high speeds (>6000 rpm), slightly smaller than agitation loss. This difference arises because the relative speed between the internal needle rollers and the bushing is always equal to the input shaft speed, unlike the external needle rollers whose speed fluctuates from zero to the input speed with the engagement angle.

[0024] Reference Figure 2 The internal needle roller bushing drive method is equivalent to a bushing bearing with a large length-to-diameter ratio. The larger the diameter of the internal needle roller, the higher the equivalent bushing bearing loss; therefore, bushing loss can be reduced by decreasing the diameter of the internal needle roller. However, when the diameter of the internal needle roller is too small, it is prone to failure due to bending fatigue or surface contact fatigue. Thus, using a large-diameter needle roller-shoulder combination leads to unnecessary energy loss, reduces the operating efficiency of the cycloidal pinwheel reducer, and increases the starting torque. Therefore, providing an internal needle roller arrangement that simultaneously meets load-bearing capacity requirements while exhibiting low energy loss and low starting torque is crucial for industries using cycloidal pinwheel reducers. On the other hand, for cycloidal pinwheel reducers, due to the compression of the inner needle rollers by the cycloidal wheel and the friction of the outer needle rollers, the inner needle rollers usually fail first due to bending, while the outer needle rollers usually fail first due to surface contact fatigue. It can be seen that the lifespan of the inner and outer needle rollers depends on different failure modes. Since the lifespan of the reducer depends on the component that fails first, if the lifespan of the inner and outer needle rollers can be balanced, the lifespan of the reducer can be improved.

[0025] When the number of outer needle rollers remains constant, the more inner needle rollers there are, the greater the rated bending load of the inner needle rollers. Therefore, when designing a reducer, it is only necessary to adjust the ratio of the number of inner and outer needle rollers so that the rated fatigue load on the surface of the outer needle rollers is close to the rated bending load of the inner needle rollers, thus balancing the lifespan of the inner and outer needle rollers.

[0026] Based on the above analysis, one of the core technical concepts of this application is that by setting relatively close inner and outer needle roller diameters and a specific ratio of inner and outer needle roller numbers, it is possible to reduce the wear of the needle roller bushing, reduce the return torque, balance the service life of the inner and outer needle rollers, and reduce production and maintenance costs.

[0027] Reference Figure 3-4 and Figure 10-12 This application illustrates a cycloidal pinwheel reducer according to an embodiment of the present application, comprising: an input mechanism 1, an eccentric mechanism 2, a first bearing assembly 3, a cycloidal wheel mechanism 4, an output mechanism 5, and a frame 6; The eccentric mechanism 2 is sleeved on the input mechanism 1, and 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-apart outer needle rollers 61; the output mechanism 5 includes a plurality of spaced-apart inner needle rollers 51; each inner needle roller 51 is provided with a corresponding first bushing 511; each outer needle roller 61 is provided with a corresponding second bushing 611; wherein, the diameter ratio of the outer needle rollers 61 to the inner needle rollers 51 is 1:2-2:1, and the number of inner needle rollers 51 is 40%-60% of the number of outer needle rollers 61; The outer edge tooth profile of the cycloidal wheel mechanism 4 meshes with the outer roller needle 61, and the inner roller needle 51 and the first bushing 511 are respectively inserted through the output hole 44 of the cycloidal wheel mechanism 4. When the input mechanism 1 rotates, the input mechanism 1 drives the cycloidal wheel mechanism 4 to perform eccentric motion through the eccentric mechanism 2, and the cycloidal wheel mechanism 4 drives the output mechanism 5 to rotate through the inner needle roller 51.

[0028] In the embodiments of this application, addressing the difficulty in simultaneously meeting the technical requirements of efficiency and lifespan in the design of the number and inner diameter of the inner and outer needle rollers in existing cycloidal pinwheel reducers, this application provides a solution for rationally setting the diameter and quantity ratio of the inner needle rollers 51 and the outer needle rollers 61. Specifically, a cycloidal pinwheel reducer includes: an input mechanism 1, an eccentric mechanism 2, a first bearing assembly 3, a cycloidal wheel mechanism 4, an output mechanism 5, and a frame 6; the eccentric mechanism 2 is sleeved on the input mechanism 1, and the cycloidal wheel mechanism 4 is sleeved on the eccentric mechanism 2 via the first bearing assembly 3; the frame 6 includes a plurality of spaced outer needle rollers 61; the output mechanism 5 includes a plurality of spaced inner needle rollers 51; the inner needle rollers 61... The needle 51 is provided with a corresponding first bushing 511; the outer roller needle 61 is provided with a corresponding second bushing 611; wherein, the diameter ratio of the outer roller needle 61 and the inner roller needle 51 is 1:2-2:1, and the number of the inner roller needles 51 is 40%-60% of the number of the outer roller needles 61; the outer edge tooth profile of the cycloidal wheel mechanism 4 meshes with the outer roller needle 61, and the inner roller needle 51 and the first bushing 511 are respectively inserted into the output hole 44 of the cycloidal wheel mechanism 4; when the input mechanism 1 rotates, the input mechanism 1 drives the cycloidal wheel mechanism 4 to perform eccentric motion through the eccentric mechanism 2, and the cycloidal wheel mechanism 4 drives the output mechanism 5 to rotate through the inner roller needle 51. This application achieves reduced bushing wear of the needle rollers by setting relatively close diameters of the inner needle rollers 51 and the outer needle rollers 61, as well as a specific ratio of the number of inner needle rollers 51 and outer needle rollers 61, thereby reducing the service life of the inner needle rollers 51 and the outer needle rollers 61 and lowering production and maintenance costs.

[0029] The following will further describe a cycloidal pinwheel reducer in this exemplary embodiment.

[0030] It should be noted that, compared to the existing cycloidal pinwheel reducers where the diameter of the inner needle roller is generally more than three times larger than the diameter of the outer needle roller, the diameter ratio of the outer needle roller 61 to the inner needle roller 51 in this embodiment is 1:2-2:1, which makes the diameters of the outer needle roller 61 and the inner needle roller 51 closer, thus minimizing the diameter of the inner needle roller 51 while also meeting the actual load requirements of the inner needle roller 51.

[0031] As an example, the diameter ratio of the outer needle roller 61 to the inner needle roller 51 can be 2:3 to 3:2.

[0032] As an example, the diameter ratio of the outer needle roller 61 to the inner needle roller 51 can be 3:4 to 4:3.

[0033] As an example, the diameter ratio of the outer needle roller 61 to the inner needle roller 51 can be (n-1):nn:(n-1); where n is greater than 4.

[0034] As an example, the diameters of the outer needle roller 61 and the inner needle roller 51 can be equal. The outer needle roller 61 and the inner needle roller 51 can use the same standard part to save costs.

[0035] It should be noted that, due to the dynamic balancing requirement of at least two cycloidal wheels participating in the transmission, the bushing of the inner needle roller 51 needs to contact at least two cycloidal wheels. Therefore, the equivalent bushing bearing's length-to-diameter ratio (L / D ratio) is often greater than 3, classifying it as a finite bushing bearing. Some configurations even have an L / D ratio greater than 4.75, classifying them as long bushing bearings. Without considering rolling losses, and assuming no eccentricity and constant lubricant viscosity, the following simplified formula for bushing loss (power) can be obtained by solving the 1st Wiener-Wilhelm Stock equation:

[0036] in, Indicates bushing wear, Indicates the viscosity of the lubricant. Indicates the rotational angular velocity. Indicates the radius of the needle roller. Indicates the clearance between the needle roller and the bushing. This indicates the length of the needle roller within the bushing.

[0037] As can be seen from equation (1), under the same load, length, and clearance conditions, the needle roller radius of the bushing bearing is... The larger the diameter, the higher the bushing wear, and the bushing wear is related to the needle roller radius. They are related to the power of cubic.

[0038] In a specific implementation, refer to Figure 5 When the inner needle roller diameter is reduced from 4mm to 3mm, the loss of a single bearing becomes 42.2% of the original, significantly reducing frictional energy loss. By substituting bearing sleeves of the same length and clearance but different diameters into the elastohydrodynamic friction eccentricity-temperature rise double recursive algorithm, it can be found that under the same load, the frictional loss of the 3mm bearing sleeve is lower than that of the 4mm bearing sleeve, especially at high input speeds.

[0039] In the embodiments of this application, the needle roller can be equivalent to a simply supported beam supported at both ends and subjected to a distributed load in the middle. Under the condition of being subjected to a load from a cycloidal wheel, the bending load of the needle roller can be calculated by the following formula: Area moment:

[0040] Simply supported beam torque:

[0041] Maximum bending stress:

[0042] Where R is the needle radius, W is the applied pressure, L is the effective length of the needle, and b is the length of the center-distributed load. Combining and simplifying equations (2) and (3) into equation (4), it can be seen that under the same load, effective needle length, center-distributed load length, and the same number of needles, the maximum bending stress on the needle is... It is related to the -3 power of the needle roller radius R.

[0043] The maximum surface contact stress can be obtained using the Hertzian line contact stress formula:

[0044] in, Let be the contact modulus. Therefore, under the same load, center-distributed load length, and the same number of needle rollers, the maximum contact stress on the needle roller is... With needle roller radius They are related to the power of -0.5.

[0045] From equations (1), (4), and (5) above, it can be seen that the bushing wear increases with the needle roller radius. The maximum bending stress decreases as the value decreases. and maximum contact stress All depend on the radius of the needle roller The diameter of the needle roller decreases as the wear increases; therefore, setting a reasonable needle roller diameter can achieve a balance between reducing wear and preventing fatigue. Since the effective lengths of the inner and outer needle rollers in a cycloidal pinwheel reducer are basically the same, the minimum usable radius of the inner and outer needle rollers can be equal. As an example, the diameters of the outer and inner needle rollers can be 3-4 mm.

[0046] In one specific implementation, the rated load of the outer needle rollers under rated life and speed can be calculated first through a fatigue model. Then, by gradually increasing the number of inner needle rollers, their rated load capacity can be made close to that of the outer needle rollers, thereby keeping the overall life of the reducer consistent.

[0047] With the diameters of both the outer and inner needle rollers set to 3mm, the surface rated fatigue load and bending rated load of the inner and outer needle rollers can be calculated under the same rated reducer life (6000 hours) and rated reducer output speed (200rpm) for different numbers of inner needle rollers.

[0048] In one specific embodiment of this application, the number of outer needle rollers is set to 20, and the number of inner needle rollers is set to 6-14. The rated load test results of this embodiment are shown in the table below:

[0049] It should be noted that when the number of inner needle rollers is 8-12, which is 40%-60% of the number of outer needle rollers, the rated bending load of the inner needle rollers and the rated fatigue load on the surface of the outer needle rollers differ by a maximum of about 20%, thus achieving a balance in the lifespan of the inner and outer needle rollers.

[0050] When the number of inner needle rollers is 9-11, which is 45%-55% of the number of outer needle rollers, the rated bending load of the inner needle rollers and the rated fatigue load of the outer needle rollers are only about 10% apart, further achieving a balance in the lifespan of the inner and outer needle rollers.

[0051] In one specific embodiment of this application, the number of outer needle rollers is set to 24, and the number of inner needle rollers is set to 7-17. The rated load test results of this embodiment are shown in the table below:

[0052] It should be noted that when the number of inner needle rollers is 11-15, which is 50%-58% of the number of outer needle rollers, the difference between the rated bending load of the inner needle rollers and the rated fatigue load of the outer needle rollers is less than 10%, thus achieving a balance in the lifespan of the inner and outer needle rollers.

[0053] In one specific embodiment of this application, the number of outer needle rollers is set to 32, and the number of inner needle rollers is set to 10-22. The rated load test results of this embodiment are shown in the table below:

[0054] It should be noted that when the number of inner needle rollers is 13-18, which is 41%-56% of the number of outer needle rollers, the difference between the rated bending load of the inner needle rollers and the rated fatigue load of the outer needle rollers is less than 20%, thus achieving a balance in the lifespan of the inner and outer needle rollers.

[0055] When the number of inner needle rollers is 14-16, which is 44%-50% of the number of outer needle rollers, the difference between the rated bending load of the inner needle rollers and the rated fatigue load of the outer needle rollers is less than 10%, further achieving a balance in the lifespan of the inner and outer needle rollers.

[0056] Therefore, when the number of inner needle rollers is close to 50% of the number of outer needle rollers, the difference between the rated bending load of the inner needle rollers and the rated surface fatigue load of the outer needle rollers can be smaller. This ensures that the inner needle rollers, which are more prone to bending fatigue failure, and the outer needle rollers, which are more prone to surface contact fatigue failure, have almost the same service life, thus balancing the service life of the entire reducer. When maintenance or replacement of parts is required, the inner and outer needle rollers can also be replaced at the same time, reducing the maintenance cost of the reducer.

[0057] In a specific implementation, taking a cycloidal pinwheel reducer with 20 external needle rollers as an example, calculations show that when the inner needle roller diameter is 4mm and the number is 8, the efficiency loss of a single bushing corresponding to the inner needle roller at an input speed of 6000rpm is 0.4w, and the total efficiency loss of the bushing is 3.2w. However, when the inner needle roller diameter is 3mm and the number is 10, the efficiency loss of a single bushing corresponding to the inner needle roller at an input speed of 6000rpm is 0.18w, and the total efficiency loss of the bushing is 1.8w. It can be seen that the total efficiency loss of the bushing is reduced by 43.75%. Therefore, the optimal diameter and number of inner and outer needle rollers can be reasonably matched according to the load conditions, thus ensuring that the efficiency of the entire reducer is maximized while meeting the load requirements.

[0058] In one embodiment of this application, the diameter ratio of the outer roller needle 61 to the inner roller needle 51 is 1:2, 1:1 or 2:1; the number of the inner roller needles 51 is 40%, 50% or 60% of the number of the outer roller needles 61.

[0059] It should be noted that, in any embodiment of this application, since the number of inner needle rollers 51 and outer needle rollers 61 can only be an integer, the actual number should be rounded down according to the ratio of the number of inner needle rollers 51 to the number of outer needle rollers 61.

[0060] Reference Figure 10 For example, the number of outer needle rollers 61 is 20, and the number of inner needle rollers 51 is 10.

[0061] Reference Figure 11 For example, the number of outer needle rollers 61 is 24, and the number of inner needle rollers 51 is 12.

[0062] Reference Figure 12 For example, the number of outer needle rollers 61 is 32, and the number of inner needle rollers 51 is 16.

[0063] In one specific embodiment of this application, the outer needle rollers 61 are arranged in a circular array on the frame 6; the inner needle rollers 51 are arranged in a circular array on the output mechanism 5.

[0064] Reference Figure 4 In one embodiment of this application, the input mechanism 1 includes an input shaft 11 and a cylindrical pin 12; The eccentric mechanism 2 is sleeved on the input shaft 11 via the cylindrical pin 12.

[0065] It should be noted that the input shaft 11 may have a groove that matches the shape of the cylindrical pin top. 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. This maximizes the hollow diameter inside the input shaft 11 while ensuring structural strength.

[0066] Reference Figure 6 In one embodiment of this application, the eccentric mechanism 2 includes a first eccentric bushing 21 and a second eccentric bushing 22; The first eccentric bushing 21 is provided with a first eccentric wheel 211; the second eccentric bushing 22 is provided with a second eccentric wheel 221; the first eccentric bushing 21 and the second eccentric bushing 22 abut against each other along the axial direction, and a third eccentric wheel 23 is formed at the abutment portion; The cycloidal wheel mechanism 4 is sleeved on the first eccentric wheel 211, the second eccentric wheel 221 and the third eccentric wheel 23 via the first bearing assembly 3.

[0067] It should be noted that the eccentric mechanism 2 consists of three corresponding eccentric wheels formed by two independent first eccentric bushings 21 and second eccentric bushings 22. To meet the dynamic balance requirements of the cycloidal wheels, the third eccentric wheel 23 must have a 180° phase angle (eccentricity) relative to the first eccentric wheel 211 and the second eccentric wheel 221. Since the third eccentric wheel 23 is formed by the contact part of the first eccentric bushing 21 and the second eccentric bushing 22, the third eccentric wheel 23 with a 180° phase angle (eccentricity) will not affect the assembly of the three cycloidal wheels.

[0068] Reference Figure 13-14 In one embodiment of this application, the first bearing assembly 3 includes: a first eccentric bearing 31, a second eccentric bearing 32, and a third eccentric bearing 33; The first eccentric bearing 31 is sleeved on the first eccentric wheel 211; the second eccentric bearing 32 is sleeved on the second eccentric wheel 221; and the third eccentric bearing 33 is sleeved on the third eccentric wheel 23.

[0069] It should be noted that the first eccentric bearing 31, the second eccentric bearing 32 and the third eccentric bearing 33 can all be standard thin-walled deep groove ball bearings.

[0070] Reference Figure 13-14 In one embodiment of this application, the cycloidal wheel mechanism 4 includes a first cycloidal wheel 41, a second cycloidal wheel 42, and a third cycloidal wheel 43; The first cycloidal wheel 41 is sleeved on the first eccentric bearing 31; the second cycloidal wheel 42 is sleeved on the second eccentric bearing 32; and the third cycloidal wheel 43 is sleeved on the third eccentric bearing 33.

[0071] It should be noted that the first cycloidal wheel 41 and the second cycloidal wheel 42 may have the same phase, and the third cycloidal wheel 43 may maintain a phase difference of 180° relative to the first cycloidal wheel 41 and the second cycloidal wheel 42. The first cycloidal wheel 41 and the second cycloidal wheel 42 are respectively disposed on both sides of the third cycloidal wheel 43.

[0072] Reference Figure 8 and Figure 15 In one 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, the gasket assembly 8 is connected between the first bearing assembly 3 and the second bearing assembly 7, and the gasket assembly 8 is disposed in the slit channel 84 formed by the eccentric mechanism 2, the first bearing assembly 3, the input mechanism 1 and the second bearing assembly 7.

[0073] 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.

[0074] Both the inner needle roller 51 and the first bearing assembly 3 are provided with grease for lubrication. Since the second bearing assembly 7 is the bearing of the input shaft 11 and rotates at the highest speed, it is most prone to grease leakage. A grease slit channel 84 is formed between the first inner housing 52, the first input bearing 71, and the first eccentric bearing 31, and also between the second inner housing 53, the second input bearing 72, and the second eccentric bearing 32. By placing the corresponding gasket assembly 8 in the slit channel 84, the difficulty of grease leakage from the corresponding input shaft 11 can be increased, thereby reducing grease leakage.

[0075] Reference Figure 15 In one embodiment of this application, the gasket assembly 8 includes a first gasket 81; the first gasket 81 is sleeved on the eccentric mechanism 2, and one end face of the first gasket 81 abuts against the first bearing assembly 3; wherein, the outer diameter of the first gasket 81 is greater than the center diameter of the corresponding bearing in the first bearing assembly 3, and smaller than the inner diameter of the outer ring of the corresponding bearing.

[0076] It should be noted that the first shim 81 can be used to prevent grease leakage from the eccentric bearing, and can also serve as a limiting structure for the eccentric bearing. If the outer diameter of the first shim 81 is larger than the inner diameter of the outer ring of the eccentric bearing, the first shim 81 will rub against the outer ring of the eccentric bearing and cause damage, because the first shim 81 will move eccentrically in coordination with the inner ring of the eccentric bearing.

[0077] Reference Figure 15 In one embodiment of this application, the gasket assembly 8 further includes a second gasket 82; the second gasket 82 is sleeved on the input shaft 11, and one end face of the second gasket 82 abuts against the end of the eccentric mechanism 2, the cylindrical pin 12 and the other end face of the first gasket 81.

[0078] It should be noted that the second gasket 82 can serve as an axial limiting structure for the eccentric mechanism 2, the cylindrical pin 12, and the first gasket 81. The second gasket 82 is positioned between the first gasket 81 and the third gasket 83, forming the main structure of the gasket assembly 8 to maximize the blockage of the grease slit channel 84. The thickness of the second gasket 82 should be designed to avoid friction with the inner wall of the output mechanism 5. The outer diameter of the second gasket 82 must be greater than the inner diameter of the eccentric bearing plus twice the eccentricity of the cycloidal wheel, calculated using the following formula:

[0079] in, The outer diameter of the second gasket. For the eccentricity of the cycloidal wheel, This is the inner diameter of the eccentric bearing.

[0080] Reference Figure 15 In one embodiment of this application, the gasket assembly 8 further includes a third gasket 83; the third gasket 83 is sleeved on the input shaft 11, one end face of the third gasket 83 abuts against the other end face of the second gasket 82, and the other end face of the third gasket 83 abuts against the second bearing assembly 7; wherein, the outer diameter of the third gasket 83 is larger than the center diameter of the corresponding bearing in the second bearing assembly 7, and smaller than the inner diameter of the outer ring of the corresponding bearing.

[0081] It should be noted that the third gasket 83 serves as an intermediate component to prevent the second gasket 82 from rubbing against the input shaft 11 bearing. The third gasket 83 prevents grease from entering the input shaft 11 bearing through the slit channel 84, thus preventing grease leakage. If the outer diameter of the third gasket 83 is larger than the inner diameter of the outer ring of the input shaft 11 bearing, the third gasket 83 will rub against the outer ring of the input shaft 11 bearing, causing damage, because it will move in tandem with the inner ring of the input shaft 11 bearing.

[0082] Reference Figure 8In a specific embodiment of this application, the second bearing assembly 7 includes a first input bearing 71 and a second input bearing 72; one side of the first input bearing 71 abuts against the shoulder of the input shaft 11 and the limiting structure inside the output mechanism 5, and the other side of the first input bearing 71 abuts against the gasket assembly 8 near the first eccentric bushing 21; one end of the input shaft 11 is provided with an annular connector 112 for axially limiting the components of the input shaft 11, one side of the second input bearing 72 abuts against the annular connector 112 of the input shaft 11, and the other side of the second input bearing 72 abuts against the gasket assembly 8 near the second eccentric bushing 22.

[0083] Reference Figure 7-8 In one embodiment of this application, it further includes: a third bearing assembly 9; the frame 6 is sleeved on the output mechanism 5 through the third bearing assembly 9.

[0084] 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.

[0085] Reference Figure 7-8 In a specific embodiment of this application, the third bearing assembly 9 includes a first output bearing 91 and a second output bearing 92. One side of the first output bearing 91 abuts against a limiting structure on the outside of the output mechanism 5, and the other side of the first output bearing 91 abuts against a limiting structure on the inside of the frame 6.

[0086] Reference Figure 7-9 In one specific embodiment of this application, the frame 6 includes a first outer shell 62 and a second outer shell 63 adapted thereto. The second outer shell 63 is disposed on the side of the first outer shell 62 away from the input end of the input mechanism 1. The first outer shell 62 and the second outer shell 63 are connected by screws. The inner sides of the first outer shell 62 and the second outer shell 63 are respectively provided with openings for accommodating both ends of the outer roller needle 61. One end of the outer roller needle 61 is connected to the opening of the first outer shell 62 through a second bushing 611, and the other end of the outer roller needle 61 is connected to the opening of the second outer shell 63 through a second bushing 611. Each outer roller needle 61 corresponds to two second bushings 611, and the second bushings 611 are respectively disposed in the openings of the first outer shell 62 and the second outer shell 63.

[0087] Reference Figure 7-9In a specific embodiment of this application, the output mechanism 5 includes a first inner housing 52 and a second inner housing 53 adapted thereto. The second inner housing 53 is disposed on the side of the first inner housing 52 away from the input end of the input mechanism 1, and the second inner housing 53 may have an opening for output torque. The inner sides of the first inner housing 52 and the second inner housing 53 are respectively provided with openings for accommodating both ends of the inner roller needle 51; one end of the inner roller needle 51 is connected to the opening of the first outer housing 62, and the other end of the inner roller needle 51 is connected to the opening of the second outer housing 63; a first bushing 511 is provided on the outer side of the inner roller needle 51, and the first bushing 511 is disposed between the first inner housing 52 and the second inner housing 53. The output hole 44 of the cycloidal wheel mechanism 4 is connected to the inner roller needle 51 through the first bushing 511.

[0088] It should be noted that the inner needle roller 51 can be used to support the first bushing 511, allowing the first bushing 511 to have pure rolling friction with the cycloidal wheel. The inner needle roller 51 and the first bushing 511 are equivalent to a bushing bearing that experiences sliding friction. Compared to the inner needle roller 51, which is similar to a cantilever beam structure, the inner needle roller 51 in this embodiment is equivalent to a more stable simply supported beam structure that smoothly transmits the output torque to the first inner housing 52 and the second inner housing 53, reducing the failure of the inner needle roller 51 due to bending fatigue.

[0089] 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.

[0090] 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.

[0091] The above provides a detailed description of a cycloidal pinwheel reducer provided in this application. Specific examples have been used to illustrate the principle and implementation of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core idea of ​​this application. At the same time, for those skilled in the art, there will be changes in the specific implementation and application scope based on the idea of ​​this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A cycloidal pinwheel reducer, characterized in that, include: Input mechanism, eccentric mechanism, first bearing assembly, cycloidal wheel mechanism, output mechanism and frame; The eccentric mechanism is sleeved on the input mechanism, and the cycloidal wheel mechanism is sleeved on the eccentric mechanism through the first bearing assembly; The frame includes a plurality of spaced-apart outer needle rollers; the output mechanism includes a plurality of spaced-apart inner needle rollers; each inner needle roller is provided with a corresponding first bushing; each outer needle roller is provided with a corresponding second bushing; wherein the diameter ratio of the outer needle rollers to the inner needle rollers is 1:2-2:1, and the number of inner needle rollers is 40%-60% of the number of outer needle rollers; The outer edge tooth profile of the cycloidal wheel mechanism meshes with the outer roller needle, and the inner roller needle and the first bushing are respectively inserted through the output hole of the cycloidal wheel mechanism; When the input mechanism rotates, it drives the cycloidal wheel mechanism to perform eccentric motion through the eccentric mechanism, and the cycloidal wheel mechanism drives the output mechanism to rotate through the inner needle roller.

2. The reducer according to claim 1, characterized in that, The diameter ratio of the outer needle roller to the inner needle roller is 1:2, 1:1, or 2:1; the number of inner needle rollers is 40%, 50%, or 60% of the number of outer needle rollers.

3. The reducer according to claim 1, characterized in that, The input mechanism includes an input shaft and a cylindrical pin; The eccentric mechanism is sleeved on the input shaft by the cylindrical pin.

4. The reducer according to claim 3, characterized in that, The eccentric mechanism includes a first eccentric bushing and a second eccentric bushing; The first eccentric bushing is provided with a first eccentric wheel; the second eccentric bushing is provided with a second eccentric wheel; the first eccentric bushing and the second eccentric bushing abut against each other along the axial direction, and a third eccentric wheel is formed at the abutment portion; The cycloidal wheel mechanism is sleeved on the first eccentric wheel, the second eccentric wheel, and the third eccentric wheel via the first bearing assembly.

5. The reducer according to claim 4, characterized in that, The first bearing assembly includes: a first eccentric bearing, a second eccentric bearing, and a third eccentric bearing; The first eccentric bearing is sleeved on the first eccentric wheel; the second eccentric bearing is sleeved on the second eccentric wheel; and the third eccentric bearing is sleeved on the third eccentric wheel.

6. The reducer according to claim 5, characterized in that, The cycloidal wheel mechanism includes a first cycloidal wheel, a second cycloidal wheel, and a third cycloidal wheel; The first cycloidal wheel is sleeved on the first eccentric bearing; the second cycloidal wheel is sleeved on the second eccentric bearing; and the third cycloidal wheel is sleeved on the third eccentric bearing.

7. The reducer according to claim 3, characterized in that, Also includes: Second bearing assembly and gasket assembly; The output mechanism is sleeved on the input shaft via the second bearing assembly; The gasket assembly is sleeved on the input mechanism, the gasket assembly is connected between the first bearing assembly and the second bearing assembly, and the gasket assembly is disposed in the slit channel formed by the eccentric mechanism, the first bearing assembly, the input mechanism and the second bearing assembly.

8. The reducer according to claim 7, characterized in that, The gasket assembly includes a first gasket; the first gasket is sleeved on the eccentric mechanism, and one end face of the first gasket abuts against the first bearing assembly; wherein, the outer diameter of the first gasket is greater than the center diameter of the corresponding bearing in the first bearing assembly, and smaller than the inner diameter of the outer ring of the corresponding bearing.

9. The reducer according to claim 8, characterized in that, The gasket assembly further includes a second gasket; the second gasket is sleeved on the input shaft, and one end face of the second gasket abuts against the eccentric mechanism, the end of the cylindrical pin, and the other end face of the first gasket.

10. The reducer according to claim 9, characterized in that, The gasket assembly further includes a third gasket; the third gasket is sleeved on the input shaft, one end face of the third gasket abuts against the other end face of the second gasket, and the other end face of the third gasket abuts against the second bearing assembly; wherein, the outer diameter of the third gasket is larger than the center diameter of the corresponding bearing in the second bearing assembly, and smaller than the inner diameter of the outer ring of the corresponding bearing.

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