Precise cycloidal pin gear speed reducer

Abstract

A precise cycloidal pin gear speed reducer uses a free eccentric shaft (3) and a suspended input shaft (4), the free eccentric shaft (3) is sleeved on a rotating arm shaft (21) through a hollow shaft hole of the free eccentric shaft (3), and each cycloidal gear (5) is sleeved on each eccentric shaft section of the free eccentric shaft (3) through a shaft hole of the cycloidal gear (5) to form inner and outer layer rotating connection. And the suspended input shaft (4) is directly and rotationally connected with each cycloidal gear (5) only at each eccentric shaft section and is not directly and rotationally connected with the base (1) or the planet carrier (2), so that the suspended input shaft (4) is suspended on the base (1) and the planet carrier (2). According to the special design, radial force borne by the input shaft can be reduced, a thin input shaft is allowed to be used, the service life is long, and the requirement for manufacturing precision is low.

Description

Technical Field

[0001] The present application relates to a reducer, and in particular to a cycloid pinwheel reducer. Background Art

[0002] This section is intended to provide a background or context for the embodiments of the present application as stated in the claims. The contents in this section are for reference only and do not constitute an admission or confirmation that they are prior art that has been disclosed.

[0003] The cycloid pinwheel transmission technology was first invented by Germany in 1937. After Japan purchased the patent rights in 1939, it successfully manufactured a cycloid pinwheel reducer with a large transmission ratio. This technology is widely used in various industries around the world and continues to be used to this day. Its working principle is: the cycloid wheel is driven by the central input eccentric shaft, swings along the eccentric circle, and meshes with the pin teeth. Based on the principle of small tooth difference, one circle of the cycloid wheel will drive it to rotate relative to the pin gear housing, and the rotation angle corresponds to the small tooth difference. Through the swing arm shaft in the cycloid wheel, this rotation can be transmitted to the planetary carrier output. Cycloid pinwheel reducers are widely used due to their high transmission ratio, high efficiency and long service life. However, due to the huge radial force to be borne, the input eccentric shaft in the center needs to be made very thick, at the cost of occupying the valuable effective area of ​​the cycloid wheel, resulting in the inability to further increase the diameter of the swing arm hole, limiting the further improvement of the output capacity.

[0004] To solve this problem, Teijin Seiki (now Nabtesco Corporation) developed the RV reducer in 1985. The device retains the cycloid pinwheel reducer, removes the central input eccentric shaft, and introduces a parallel double crank (or parallel four-link) mechanism to unify the input and output to multiple crank shafts on the periphery of the cycloid wheel. This improvement removes the central eccentric shaft, giving the RV reducer the highest output capacity and stiffness currently available. In addition, in order to achieve synchronous drive of multiple cranks, the RV reducer adds a front-stage spur gear reduction part, which drives multiple planetary spur gears simultaneously through the sun gear to drive their respective cranks to achieve synchronous input. Although this design solves the problem of synchronous input, it also introduces the problem of over-constraint (or over-positioning): the shaft hole on the cycloid wheel has constrained each crank to maintain phase synchronization, and the rigid transmission through the meshing of the front-stage sun gear and the planetary gears again constrains the phase of each crankshaft, resulting in over-constraint. This design not only requires extremely high manufacturing precision, but may also affect the service life, so that even the most well-made RV reducer has a service life of only 6,000 hours, which is far lower than the tens of thousands of hours of service life of traditional cycloid pinwheel reducers.

[0005] The industry is seeking to develop a new type of precision cycloidal pinwheel reducer that is designed to combine the advantages of traditional cycloidal pinwheel reducers and RV reducers. Specifically, this new type of reducer needs to have the following characteristics: compared with traditional cycloidal pinwheel reducers, its input shaft is subjected to less radial force, allowing the use of a thinner input shaft to leave more space for the output mechanism; at the same time, compared with RV reducers, this new type of reducer should have a longer service life and lower manufacturing precision requirements to reduce production costs and improve production efficiency. Such technological innovations will provide more efficient and economical power transmission solutions for all walks of life. Summary of the invention

[0006] The purpose of the present application is to provide a precision cycloid pinwheel reducer, which can not only reduce the radial force borne by the input shaft and allow the use of a thinner input shaft, but also has a long service life and low manufacturing precision requirements.

[0007] The present application discloses a precision cycloid pinwheel reducer, comprising: a base, a plurality of cycloid wheels, a suspended input shaft, a planetary frame having a plurality of swing arm shafts, and a free eccentric shaft sleeved on each of the swing arm shafts; the base comprises a pin gear housing, a plurality of pin teeth are arranged on the inner wall of the pin gear housing; the edge of the cycloid wheel comprises a plurality of cycloid teeth matched with the pin teeth, the number of the cycloid teeth is less than the number of the pin teeth; the free eccentric shaft comprises a through hollow shaft hole and a number of first eccentric shaft segments equal to the number of the cycloid wheels, each first eccentric shaft segment corresponds to one of the cycloid wheels; the cycloid wheel is provided with a shaft hole matched with the first eccentric shaft segment ; The swing arm shaft passes through the hollow shaft hole of the free eccentric shaft; the free eccentric shaft passes through the shaft hole of each cycloidal wheel at its first eccentric shaft segments respectively, forming an inner and outer two-layer rotation connection; the suspended input shaft includes a central shaft and second eccentric shaft segments equal in number to the cycloidal wheels, each of the second eccentric shaft segments passes through the center of a cycloidal wheel and is rotationally connected to the cycloidal wheel; the central shaft is used to input external torque to drive each second eccentric shaft segment to rotate; the suspended input shaft is directly rotationally connected to each cycloidal wheel only at each second eccentric shaft segment, and the suspended input shaft is not directly rotationally connected to the base or the planetary carrier.

[0008] In a preferred example, when the suspended input shaft rotates, each second eccentric shaft segment on the suspended input shaft drives each cycloidal wheel to swing along an eccentric circle, so that the cycloidal teeth on the edge of the cycloidal wheel contact and engage with the needle teeth on the needle tooth housing, causing the cycloidal wheel to rotate; when the cycloidal wheel swings, it drives each free eccentric shaft passing through the axial hole of the cycloidal wheel to rotate synchronously, and applies radial force and planetary torque to each free eccentric shaft; each free eccentric shaft further transmits the planetary torque to the swing arm shaft passing through its center, so that the swing arm shaft also rotates accordingly; the torque applied to each swing arm shaft is combined into the output torque of the planetary carrier.

[0009] In a preferred example, the planet carrier further includes an output shaft for outputting the output torque of the planet carrier outward.

[0010] In a preferred example, a rolling bearing is provided between the base and the output shaft of the planetary carrier, the inner ring of the rolling bearing is fixedly connected to the output shaft, and the outer ring of the rolling bearing is fixedly connected to the base.

[0011] In a preferred example, the rolling bearing is a crossed roller bearing.

[0012] In a preferred embodiment, three cycloidal wheels are included, wherein the eccentric angles of the two side cycloidal wheels on both sides are the same and differ by 180° from the eccentric angle of the middle cycloidal wheel in the center; the thickness of the two side cycloidal wheels is equal and is half of the thickness of the middle cycloidal wheel.

[0013] In a preferred example, each of the first eccentric shaft segments and each of the second eccentric shaft segments have the same eccentricity.

[0014] In a preferred example, the number of shaft holes on each of the cycloid wheels that cooperate with the first eccentric shaft segment of the free eccentric shaft is equal to the number of the swing arm shafts.

[0015] In a preferred example, it includes a multi-stage reduction mechanism, the pin gear housing is shared by the multi-stage reduction mechanism, the planetary carrier of the adjacent front-stage reduction mechanism is fixedly connected to the suspended input shaft of the rear-stage reduction mechanism and rotates coaxially, and each stage of the reduction mechanism includes multiple cycloidal wheels and multiple free eccentric shafts belonging to this stage.

[0016] In a preferred embodiment, the numbers of cycloid teeth of cycloid wheels of different stages are different.

[0017] In the implementation mode of the present application, the free eccentric shaft is sleeved on the swing arm shaft through its hollow shaft hole, and each cycloidal wheel is sleeved on each eccentric shaft segment of the free eccentric shaft through its shaft hole, forming an inner and outer rotational connection (the free eccentric shaft and the swing arm shaft are the inner rotational connection, and the free eccentric shaft and the cycloidal wheel are the outer rotational connection), and the suspended input shaft is directly rotationally connected to each cycloidal wheel only at each eccentric shaft segment, and is not directly rotationally connected to the base or the planetary carrier, so it is suspended from the base and the planetary carrier. This special design greatly reduces the maximum radial force that the input shaft may bear, so that the input shaft diameter can be relatively small, and thus the diameter of the cycloidal wheel can be reduced accordingly. As a result, the diameter and weight of the entire cycloidal pinwheel reducer are reduced, and it has a higher torque density, which is extremely important for applications that require high precision such as robots and surgical machinery. In comparison, the input shaft of a traditional cycloid pinwheel reducer is not only directly connected to the cycloid wheel, but also needs to be connected to the base or planetary carrier. The input shaft needs to withstand all radial forces from the pin teeth during operation, which may even cause the input shaft to break. To prevent this, the input shaft is usually designed to be thicker, occupying a larger central space of the cycloid wheel, forcing the cycloid wheel to be designed larger, thereby increasing the diameter and weight of the entire device.

[0018] In addition, by simply adding a cycloid wheel and a cascade planetary carrier, a first-stage reduction mechanism can be added to realize a cascade cycloid pinwheel reducer. By using cycloid wheels with different tooth differences (such as one tooth difference, two tooth differences, three tooth differences, etc.) in the reduction mechanisms at different stages, a diversified transmission ratio series can be constructed, thereby directly replacing the existing cascade involute gear planetary reducer.

[0019] Each technical feature disclosed in the above invention content, each technical feature disclosed in each implementation mode and example below, and each technical feature disclosed in the accompanying drawings can be freely combined with each other to form various new technical solutions (these technical solutions should be deemed to have been recorded in this specification), unless such combination of technical features is technically infeasible. For example, in one example, feature A+B+C is disclosed, and in another example, feature A+B+D+E is disclosed, and features C and D are equivalent technical means that play the same role. Technically, only one of them can be used, and it is impossible to use them at the same time. Feature E can be combined with feature C technically. Then, the solution of A+B+C+D should not be deemed to have been recorded because it is technically infeasible, while the solution of A+B+C+E should be deemed to have been recorded. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a simplified motion diagram of the transmission mechanism of a precision cycloid pinwheel reducer according to one embodiment of the present application;

[0021] Figure 2is an appearance diagram of a precision cycloid pinwheel reducer according to an embodiment of the present application;

[0022] Figure 3 is a parts diagram of a precision cycloid pinwheel reducer according to an embodiment of the present application;

[0023] Figure 4 is a horizontal cross-sectional view of a precision cycloid pinwheel reducer according to an embodiment of the present application;

[0024] Figure 5 is a vertical cross-sectional view of a precision cycloid pinwheel reducer according to an embodiment of the present application;

[0025] Figure 6 is a simplified motion diagram of a transmission mechanism of a cascaded cycloid pinwheel reducer according to an embodiment of the present application;

[0026] Figure 7 It is a structural diagram of a cascade planetary carrier of a cascade cycloid pinwheel reducer according to an embodiment of the present application.

[0027] The reference numerals used in the drawings are summarized as follows:

[0028] 1: Base

[0029] 11: Needle gear housing

[0030] 12: Needle teeth

[0031] 13: Back cover

[0032] 14: Rolling bearings

[0033] 15: Gap

[0034] 16: Output bearing

[0035] 2: Planet carrier

[0036] 21: Rotating arm shaft

[0037] 22: Output shaft

[0038] 3: Free eccentric shaft

[0039] 4: Suspended input shaft

[0040] 5: Cycloidal wheel

[0041] 6: Primary reduction mechanism

[0042] 7: Two-stage reduction mechanism

[0043] 8: Cascade planet carrier

[0044] 81: Rear stage input shaft

[0045] 82: Front stage arm shaft DETAILED DESCRIPTION

[0046] In the following description, many technical details are provided to help readers better understand the present application. However, those skilled in the art can understand that the technical solution claimed in the present application can be implemented even without these technical details and various changes and modifications based on the following embodiments.

[0047] In order to make the objectives, technical solutions and advantages of the present application clearer, the implementation methods of the present application will be further described in detail below in conjunction with the accompanying drawings.

[0048] The embodiment of the present application relates to a precision cycloid pinwheel reducer, such as Figure 1-Figure 5 As shown, the precision cycloid pinwheel reducer includes a base 1, a plurality of cycloid wheels 5, a suspended input shaft 4, a planetary carrier 2 having a plurality of swing arm shafts 21, and a free eccentric shaft 3 sleeved on each swing arm shaft 21.

[0049] The base 1 comprises a needle tooth housing 11 , and a plurality of needle teeth 12 are arranged on the inner wall of the needle tooth housing 11 .

[0050] The edge of the cycloid wheel 5 includes a plurality of cycloid teeth that match the needle teeth 12, and the number of the cycloid teeth is less than the number of the needle teeth 12. It can be one tooth difference, two teeth difference, three teeth difference, etc.

[0051] The free eccentric shaft 3 includes a through hollow shaft hole and the same number of first eccentric shaft sections as the cycloidal wheel 5, and each first eccentric shaft section corresponds to a cycloidal wheel 5. The cycloidal wheel 5 is provided with a shaft hole that matches the first eccentric shaft section. The swing arm shaft 21 passes through the hollow shaft hole of the free eccentric shaft 3. The free eccentric shaft 3 passes through the shaft holes of the cycloidal wheel 5 in each of its first eccentric shaft sections, forming a rotation connection between the inner and outer layers. The number of shaft holes on each cycloidal wheel 5 that matches the first eccentric shaft section of the free eccentric shaft 3 is equal to the number of swing arm shafts 21.

[0052] The suspended input shaft 4 includes a central shaft and second eccentric shaft segments equal in number to the cycloidal wheels 5, each second eccentric shaft segment respectively passes through the center of a cycloidal wheel 5 and is rotatably connected to the cycloidal wheel 5. Each first eccentric shaft segment and each second eccentric shaft segment have the same eccentricity. The central shaft refers to a non-eccentric shaft end connected to an external power component (such as an electric motor), which is used to input external torque to drive each second eccentric shaft segment to rotate. The suspended input shaft 4 is directly rotatably connected to each cycloidal wheel 5 only at each second eccentric shaft segment, and the suspended input shaft 4 is not directly rotatably connected to the base 1 or the planetary carrier 2.

[0053] The input shaft of an existing cycloidal pinwheel reducer is usually not only rotationally connected to the cycloidal wheel, but also directly rotationally connected to the base or planetary carrier through bearings and the like. However, the suspended input shaft of the embodiment of the present application is only directly rotationally connected to the cycloidal wheel, and a gap is left between the input shaft and the base (such as the back cover of the pinion housing, etc.), without contact or direct connection. The advantage of this is that when the input shaft is subjected to radial force, it will produce a slight displacement and deformation, so that most of the radial force is borne by the free eccentric shaft. This ingenious design greatly reduces the stress on the input shaft, thereby reducing the shaft diameter, giving the effective area of ​​the cycloidal wheel to the swing arm hole, allowing the use of a thick swing arm shaft, greatly improving the output capacity.

[0054] When the suspended input shaft 4 is driven to rotate by the external motor components, each second eccentric shaft segment on the suspended input shaft 4 drives each cycloid wheel 5 to swing according to the eccentric circle, so that the cycloid teeth on the edge of the cycloid wheel 5 are in contact and mesh with the pin teeth 12 on the pin gear housing 11, causing the cycloid wheel 5 to rotate. When the cycloid wheel 5 swings, it drives each free eccentric shaft 3 passing through the shaft hole of the cycloid wheel 5 to rotate synchronously, and applies radial force and planetary torque to each free eccentric shaft 3. Each free eccentric shaft 3 further transmits the planetary torque to the swing arm shaft 21 passing through its center, causing the swing arm shaft 21 to rotate accordingly. The torque applied to each swing arm shaft 21 is combined into the output torque of the planet carrier 2.

[0055] The planet carrier 2 further includes an output shaft 22 for outputting the output torque of the planet carrier 2 to the outside.

[0056] exist Figure 3 and Figure 4 In the example, the planet carrier 2 has three swing arm shafts 21 . In other embodiments, the planet carrier 2 may also have more swing arm shafts 21 .

[0057] The implementation method of the present application eliminates the over-constraint problem of the RV reducer through the structure of a free eccentric shaft and a suspended input shaft, and also solves the problem of the cycloidal pinwheel reducer input shaft being too thick. Specifically, the suspended input shaft in the center drives the cycloid wheel to swing along an eccentric circle (the shaft is an eccentric shaft, which is only rotatably connected to the cycloid wheel, and maintains a gap with the base, and is not directly connected to the planetary carrier, and is "suspended" on the base and the planetary carrier). The free eccentric shafts on each swing arm shaft rotate synchronously with the swing of the cycloid wheel, and bear huge radial forces and output torque forces; the suspended input shaft is only responsible for transmitting the swing torque to the cycloid wheel, and no longer bears huge radial forces (the central axis of the free eccentric shaft is a hollow shaft hole, which is rotatably connected to the swing arm shaft passing through the shaft hole, and can rotate freely around it). In this way, the central suspended input shaft no longer needs a large diameter, giving up the precious effective area of ​​the cycloid wheel. Thanks to this, the cycloid wheel has a swing arm hole with a large diameter, which greatly improves the output capacity. At the same time, it is easy to imagine that since the front-stage reduction part is removed, the over-constraint similar to the RV reducer no longer exists, which greatly improves the service life.

[0058] Preferably, in one embodiment, the precision cycloidal pinwheel reducer includes three cycloidal wheels 5, wherein the eccentric angles of the two side cycloidal wheels 5 located on both sides are the same, and differ from the eccentric angle of the middle cycloidal wheel 5 in the center by 180°. The thickness of the two side cycloidal wheels 5 is equal, and is half the thickness of the middle cycloidal wheel 5. Optionally, in one embodiment, all cycloidal wheels 5 use the same material. Optionally, in one embodiment, the cycloidal wheels 5 may also use different materials, and the mass of the middle cycloidal wheel 5 is equal to the sum of the masses of the two outer cycloidal wheels 5, and the thickness of the two outer cycloidal wheels 5 may not be equal. Optionally, in one embodiment, 2 or more than 3 cycloidal wheels 5 may also be used.

[0059] At present, most of the cycloid pinwheel type reducers on the market use a configuration of two cycloid wheels, which, in combination with eccentric shafts that differ by 180°, can offset most radial vibrations. However, since the radial force does not act on the same point, there is still a certain bending moment force. This bending moment acts on the root of the swing arm and still affects the output capacity and stiffness. The present application proposes a "sandwich" structure of three cycloid wheels, namely, a middle cycloid wheel and two side cycloid wheels. The eccentric shaft segments corresponding to the two side cycloid wheels have the same eccentric angle and differ by 180° from the middle eccentric shaft segment. The thickness of the two side cycloid wheels is equal and is half the thickness of the middle cycloid wheel. Such a structure completely offsets all vibrations and bending moments, so it can run very smoothly and quietly. Although the complexity is slightly increased, the volume and weight are not increased, which is very suitable for high-precision occasions such as robots. Under the same conditions, the use of a "sandwich" three-cycloid wheel structure can significantly improve the hysteresis accuracy of the reducer.

[0060] Optionally, in one embodiment, a rolling bearing 14 is provided between the base 1 and the output shaft 22 of the planetary carrier 2, the inner ring of the rolling bearing 14 is fixedly connected to the output shaft 22, and the outer ring of the rolling bearing 14 is fixedly connected to the base 1. Preferably, the rolling bearing 14 can use a cross roller bearing. The output bearing between the planetary carrier 2 and the base 1 adopts a cross roller bearing, which can obtain higher transmission accuracy and stronger bending resistance. Such a structure allows the impact force from the outside to be directly transmitted between the output shaft 22 and the base 1 without acting on the precise cycloid wheel structure. The rigidity and impact resistance are greatly improved. Of course, in some embodiments, other types of rolling bearings can also be used.

[0061] In the embodiment of the present application, the free eccentric shaft is a combination of multiple eccentric shafts with a hollow shaft hole as the central shaft, and the number of segments of the eccentric shaft is equal to the number of cycloid wheels. The cycloid wheel is sleeved on the swing arm shaft and is rotatably connected to the swing arm shaft. There is a corresponding shaft hole on the cycloid wheel, through which the free eccentric shaft passes, and is rotatably connected to the cycloid wheel. The suspended input shaft is a solid shaft, which is a combination of multiple eccentric shafts, and the number of segments of the eccentric shaft is equal to the number of cycloid wheels. All eccentric segments have the same eccentricity, and each eccentric segment corresponding to the same cycloid wheel has the same eccentric angle. It is easy to imagine that when the external input source drives the suspended input shaft to rotate, it will drive each cycloid wheel to swing (translation) according to the eccentric circle, and further make the cycloid teeth on the edge of the cycloid wheel contact and mesh with the corresponding pin teeth on the pin gear housing. At the same time, according to the principle of planetary transmission with small tooth difference, the cycloid wheel will perform planetary rotation at a slow speed. When the cycloid wheel swings one circle, it synchronously rotates the number of teeth that is less than the total number of pin teeth with a slow planetary rotation. On the other hand, when the cycloid wheel swings, it will drive the free eccentric shafts to rotate synchronously and apply radial force and planetary torque to the free eccentric shafts. The free eccentric shafts further transmit the planetary torque to the arm shaft passing through its center, and the torque received by each arm is combined into the output torque of the planet carrier.

[0062] For those skilled in the art, the eccentric shaft is generally understood as a device that converts the torque of the central shaft into eccentric circular motion, so the eccentric shaft must be fixedly connected to the central shaft. However, this application breaks through the inertia of thinking and uses a hollow "free" eccentric shaft that can rotate freely around the central shaft. This design has the following advantages over the eccentric shaft of the RV reducer:

[0063] 1. The input and output are separated, so that the structure of the front-stage sun gear driving the planetary gear input can be eliminated.

[0064] 2. The arm shaft runs through it, providing reliable support for the cycloid wheel movement and realizing a single-sided planetary carrier. The RV reducer uses two-sided planetary carriers, opens a hole in the cycloid wheel, and sets a through-core reinforced connecting shaft to achieve a fixed connection between the front and rear planetary carriers, which brings difficulties in processing and installation, occupies the valuable effective area of ​​the cycloid wheel, and limits the output capacity.

[0065] 3. The single-sided planet carrier and the pinion housing can be connected by a cross roller bearing. In this way, the impact force from the external bending moment direction can be directly transmitted between the pinion housing and the planet carrier, avoiding passing through the precise cycloid wheel and pinion gear. The RV reducer is a parallelogram structure in which the front and rear planet carriers are connected by a through-core reinforced connecting shaft. The external bending moment direction impact will inevitably be transmitted through the front and rear planet carriers, causing the parallelogram to twist and deform, and then act on the cycloid wheel and pinion gear. Therefore, the seemingly simple free eccentric shaft hollow shaft hole design solves an important key problem.

[0066] Optionally, in one embodiment, the precision cycloid pinwheel reducer may include a multi-stage reduction mechanism to form a cascade cycloid pinwheel reducer. The basic structure and Figure 1 The pin gear housing is shared by each stage of the reduction mechanism, and the planet carrier of the adjacent front stage reduction mechanism is fixedly connected with the suspended input shaft of the rear stage reduction mechanism and rotates coaxially.

[0067] Figure 6 A two-stage cascade cycloid pinwheel reducer is shown, which includes two-stage reduction mechanisms 6 and 7. The reduction mechanisms 6 and 7 respectively include a plurality of cycloid wheels 5 and a plurality of free eccentric shafts 3 belonging to the respective stages. The pin gear housing 11 is shared by the two-stage reduction mechanisms 6 and 7. Figure 7 As shown, the cascade planet carrier 8 includes a swing arm shaft 82 of the previous stage and an input shaft 81 of the subsequent stage.

[0068] Those skilled in the art will appreciate that similar Figure 6 The reduction mechanisms of more stages are cascaded in a manner.

[0069] In the multi-stage reduction mechanism of the cascaded cycloidal pinwheel reducer, the number of cycloidal teeth of each cycloidal wheel 5 inside each stage of the reduction mechanism is equal and is smaller than the number of pin teeth 12 in the pin gear housing 11, but the number of cycloidal teeth between different stages can be the same or different, so that various transmission ratios can be combined.

[0070] The advantage of the cascaded cycloid pinwheel reducer of the embodiment of the present application is that only by adding a cycloid wheel and a cascade planetary carrier, a first-stage reduction mechanism can be added. By flexibly configuring cycloid wheels with different numbers of teeth such as one tooth difference, two tooth differences, and three tooth differences in the reduction mechanisms at different stages, a rich series of transmission ratios can be formed, which can directly replace the existing cascaded involute gear planetary reducer. Cycloid wheels are more suitable for molding with materials such as nylon than involute gears, and therefore have broad market prospects.

[0071] Compared with the existing cycloid pinwheel reducers and RV reducers, it is easy to see that the present invention well combines the advantages of these two types of reducers and successfully eliminates their respective disadvantages, and is superior to the existing products in all aspects.

[0072] In summary, since the front-stage involute spur gear reduction part is removed, and thus the over-constraint is removed; and the rear planet carrier and the reinforced connecting shaft that connects the front and rear planet carriers and passes through the cycloid gear are further removed, the embodiment of the present application has the following advantages over the existing RV reducer:

[0073] 1. Long service life, which can reach the same level as the cycloid pinwheel reducer, that is, tens of thousands of hours.

[0074] 2. Output capacity is further improved.

[0075] 3. The structure is simplified, the difficulty of processing and assembly is greatly reduced, and the cost is reduced.

[0076] 4. The bending moment rigidity and torque rigidity are greatly improved, and the impact resistance is further improved.

[0077] 5. The sandwich-type three-cycloid wheel can further increase the output capacity, improve the transmission accuracy, and reduce vibration and shaking. It is very suitable for high-precision applications such as robots.

[0078] 6. The multi-stage reducer with cascade planetary carrier can form a rich product line by sharing pin gears and flexibly configuring the transmission ratio, and can be mass-produced by compression molding. It can completely replace the current multi-stage involute gear planetary reducer with its absolute advantages in output capacity, transmission accuracy, transmission efficiency, and impact resistance.

[0079] It should be noted that, in the disclosure, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. Moreover, the term "include", "comprise" or any other variant thereof is intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or equipment. In the absence of more restrictions, the elements defined by the sentence "include one" do not exclude the existence of other identical elements in the process, method, article or equipment including the elements. In this application, if it is mentioned that a certain action is performed according to a certain element, it means that at least the action is performed according to the element, which includes two situations: performing the action only according to the element and performing the action according to the element and other elements. Multiple, multiple, multiple, etc. expressions include 2, 2 times, 2 kinds and more than 2, more than 2 times, more than 2 kinds.

[0080] This specification includes combinations of the various embodiments described herein. Individual references to an embodiment (e.g., "one embodiment" or "some embodiments" or "preferred embodiments") do not necessarily refer to the same embodiment; however, these embodiments are not mutually exclusive unless indicated as mutually exclusive or it is clear to a person skilled in the art that they are mutually exclusive. It should be noted that the word "or" is used in this specification in a non-exclusive sense unless the context clearly indicates or requires otherwise.

[0081] All documents mentioned in this application are considered to be included in the disclosure of this application as a whole, so that they can be used as the basis for modification when necessary. In addition, it should be understood that after reading the content of this application, those skilled in the art can make various changes or modifications to this application, and these equivalent forms also fall within the scope of protection claimed in this application.

Claims

1. A precision cycloid pinwheel reducer, characterized in that: include: A base, a plurality of cycloid wheels, a suspended input shaft, a planet carrier having a plurality of swing arm shafts, and a free eccentric shaft sleeved on each of the swing arm shafts; The base comprises a needle tooth housing, and a plurality of needle teeth are arranged on the inner wall of the needle tooth housing; The edge of the cycloid wheel includes a plurality of cycloid teeth matched with the pin teeth, and the number of the cycloid teeth is less than the number of the pin teeth; the free eccentric shaft includes a through hollow shaft hole and a number of first eccentric shaft segments equal to the number of the cycloid wheels, and each first eccentric shaft segment corresponds to a cycloid wheel; the cycloid wheel is provided with a shaft hole matched with the first eccentric shaft segment; the swing arm shaft passes through the hollow shaft hole of the free eccentric shaft; the free eccentric shaft passes through the shaft hole of each cycloid wheel at each of its first eccentric shaft segments, forming a rotation connection between the inner and outer layers; The suspended input shaft comprises a central shaft and second eccentric shaft segments equal in number to the cycloidal wheels, each of the second eccentric shaft segments respectively passes through the center of a cycloidal wheel and is rotatably connected to the cycloidal wheel; the central shaft is used to input external torque to drive each of the second eccentric shaft segments to rotate; the suspended input shaft is directly rotatably connected to each of the cycloidal wheels only at each of the second eccentric shaft segments, and the suspended input shaft is not directly rotatably connected to the base or the planetary carrier.

2. The precision cycloid pinwheel reducer according to claim 1, characterized in that: When the suspended input shaft rotates, each second eccentric shaft segment on the suspended input shaft drives each cycloid wheel to swing along an eccentric circle, so that the cycloid teeth on the edge of the cycloid wheel are in contact and mesh with the pin teeth on the pin gear housing, causing the cycloid wheel to rotate; when the cycloid wheel swings, it drives each free eccentric shaft passing through the axial hole of the cycloid wheel to rotate synchronously, and applies radial force and planetary torque to each free eccentric shaft; each free eccentric shaft further transmits the planetary torque to the swing arm shaft passing through its center, so that the swing arm shaft also rotates accordingly; the torque applied to each swing arm shaft is combined into the output torque of the planetary carrier.

3. The precision cycloid pinwheel reducer according to claim 1, characterized in that: The planet carrier further includes an output shaft for outputting the output torque of the planet carrier outwards.

4. The precision cycloid pinwheel reducer according to claim 3, characterized in that: A rolling bearing is provided between the base and the output shaft of the planet carrier, the inner ring of the rolling bearing is fixedly connected to the output shaft, and the outer ring of the rolling bearing is fixedly connected to the base.

5. The precision cycloid pinwheel reducer according to claim 4, characterized in that: The rolling bearing is a crossed roller bearing.

6. The precision cycloid pinwheel reducer according to claim 1, characterized in that: Each of the first eccentric shaft segments and each of the second eccentric shaft segments have the same eccentricity.

7. The precision cycloid pinwheel reducer according to claim 1, characterized in that: The number of shaft holes on each of the cycloid wheels that cooperate with the first eccentric shaft section of the free eccentric shaft is equal to the number of the swing arm shafts.

8. The precision cycloid pinwheel reducer according to claim 1, characterized in that: It comprises three cycloid wheels, wherein the eccentric angles of the two side cycloid wheels on both sides are the same and differ by 180° from the eccentric angle of the middle cycloid wheel in the middle; the thicknesses of the two side cycloid wheels are equal and are half of the thickness of the middle cycloid wheel.

9. The precision cycloid reducer according to any one of claims 1 to 8, characterized in that: It comprises a multi-stage reduction mechanism, wherein the pin gear housing is shared by the multi-stage reduction mechanism, the planet carrier of the adjacent front-stage reduction mechanism is fixedly connected with the suspended input shaft of the rear-stage reduction mechanism and rotates coaxially, and each stage of the reduction mechanism comprises a plurality of cycloid wheels and a plurality of free eccentric shafts belonging to the same stage.

10. The precision cycloid pinwheel reducer according to claim 9, characterized in that: The number of cycloidal teeth of cycloidal wheels of different stages is different.

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