Planetary unit with anti-backlash structure

Abstract

The present application relates to the technical field of planetary reducer, and particularly relates to a planetary unit with a gap-eliminating structure, which comprises a planet carrier, a plurality of planet shafts arranged in the planet carrier, and an input space for accommodating a sun gear formed in the middle of the planet carrier; at least one planet shaft is provided with a gap-eliminating mechanism, and the remaining planet shafts are rotationally connected with planet gears; the gap-eliminating mechanism comprises at least two sub-gears rotationally connected with the planet shafts, and an elastic member is arranged between the sub-gears, with two ends of the elastic member being in contact with the two adjacent sub-gears respectively, so that equal misalignment angles are generated between the teeth of the sub-gears; the planet gears and the gap-eliminating mechanism are meshed with the sun gear on the side close to the input space, and are meshed with a ring gear on the side away from the input space. The present application forms misalignment between the sub-gears through the elastic member, eliminates the gap between the planet gears and the sun gear and the ring gear, and improves the positioning accuracy, reversing stability and long-term reliability of the planetary reducer.

Description

Technical Field

[0001] This invention relates to the field of planetary reducer technology, and more specifically to a planetary unit with a backlash-free structure. Background Technology

[0002] Gear meshing backlash is an indispensable key parameter in the design of planetary unit gear transmission. It refers to the clearance reserved between the non-working tooth surfaces of a pair of meshing gears. Its purpose is to compensate for gear machining errors and assembly errors, reserve space for thermal expansion of parts during operation, and ensure that lubricating oil can smoothly enter the meshing tooth surfaces to establish a stable oil film to reduce tooth surface wear and avoid damage to components caused by meshing interference. It is a basic prerequisite for ensuring the normal operation of the planetary unit.

[0003] As modern industry develops towards precision, high speed, and heavy load, high-end equipment such as new energy vehicles, industrial robots, and precision servo equipment have placed higher demands on the positioning accuracy, commutation smoothness, and long-term reliability of planetary reducers. However, the existence of gear backlash means that existing planetary units cannot meet current requirements. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a planetary unit with a backlash-eliminating structure, which eliminates the meshing backlash between gears in the planetary unit, thereby improving the positioning accuracy, commutation smoothness, and long-term reliability of the planetary reducer.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows: a planetary unit with a backlash elimination structure includes a planet carrier, a plurality of planet shafts are disposed within the planet carrier, and an input space for accommodating a sun gear is provided in the middle of the planet carrier; at least one of the planet shafts is provided with a backlash elimination mechanism, and the remaining planet shafts are rotatably connected to planet gears;

[0006] The backlash elimination mechanism includes at least two sub-gears rotatably connected to the planetary shaft. An elastic element is provided between the sub-gears, and the two ends of the elastic element contact the adjacent sub-gears on both sides, so that the relative teeth of the sub-gears produce equal misalignment angles.

[0007] The planetary gears and the backlash elimination mechanism are engaged with a sun gear on the side closer to the input space, and the planetary gears and the backlash elimination mechanism are engaged with a gear ring on the side farther from the input space.

[0008] The above solution: At least two sub-gears are misaligned using an elastic element, resulting in relative misalignment angles between the teeth of the sub-gears. When each sub-gear in the backlash elimination mechanism meshes with the sun gear and ring gear, some teeth of the sub-gears contact one side of the tooth grooves of the sun gear and ring gear, while others contact the other side, thus eliminating the intermittent meshing of the planetary gears with the sun gear and ring gear. Furthermore, the misalignment angles between the sub-gears are flexible and can float flexibly through the elastic element. When the sun gear drives the planetary gears to rotate, the elimination of backlash in at least one planetary gear position allows for more precise hovering of the planetary carrier as it rotates along the ring gear, improving the positioning accuracy of the planetary reducer. During the forward and reverse reversal operation of the sun gear, the elimination of backlash in at least one planetary gear position allows the planetary carrier to respond quickly, improving the commutation smoothness of the planetary reducer. Moreover, the elimination of backlash in at least one planetary gear position reduces friction between the planetary gears and the sun gear and ring gear, improving the long-term reliability of the planetary reducer.

[0009] Furthermore, a first support member is provided between the planetary gear and the planetary shaft, and the first support member is sleeved on the planetary shaft; a second support member is provided between the sub-gear and the planetary shaft, and the second support member is sleeved on the planetary shaft.

[0010] Furthermore, the first support member and the second support member are cylindrical sleeves or needle roller bearings.

[0011] The above solution improves the stability of the planetary gears rotating around the planetary axis through a first support member, and improves the stability of the sub-gears rotating around the planetary axis through a second support member. Specific structural forms of the first and second support members are provided. The cylindrical sleeve structure is simple and low-cost, while the needle roller bearing has a low coefficient of friction and high rotational accuracy, and can be selected according to actual needs.

[0012] Furthermore, a third support member is provided between the elastic element and the planetary shaft, and the third support member is sleeved on the planetary shaft; the third support member is a cylindrical sleeve or a needle roller bearing.

[0013] The above solution: The third support component improves the installation stability of the elastic component between the sub-gears and prevents the elastic component from directly contacting the planetary shaft and causing wear.

[0014] Furthermore, a limiting portion is provided on the adjacent end faces of the sub-gears, and the limiting portion extends to the area between the two ends of the elastic member, and a gap is provided between the side walls of the two ends of the elastic member and the side walls of the limiting portion provided on the adjacent end faces of the sub-gears.

[0015] The above solution restricts the position between the two sub-gears by setting a limiting part on the adjacent end face between the two end walls of the elastic element and the sub-gear, so that the teeth of the sub-gears form a misalignment angle; the limiting part extends to the area between the two ends of the elastic element, and a gap is set between the side wall of the limiting part and the two end walls of the elastic element, so that the elastic element can float when it deforms.

[0016] Furthermore, the sidewall adjacent to the limiting part and the elastic member is an arc surface or a plane, and the sidewall adjacent to the elastic member and the limiting part is an arc groove or a plane groove that matches the sidewall of the limiting part;

[0017] The limiting portion extends to the area between the two ends of the elastic element and makes point contact, line contact, or surface contact with the elastic element.

[0018] The above solution ensures that the limiting part can be effectively restricted to the area between the two ends of the elastic element by the arc-shaped sidewall of the limiting part and the arc-shaped groove at the end of the elastic element, and the arc-shaped surface and arc-shaped groove design reduces the sliding friction when the elastic element deforms.

[0019] Furthermore, an even number of the planetary axes are provided with backlash elimination mechanisms, and the backlash elimination mechanisms are distributed in pairs on the same radial line of the planet carrier;

[0020] The tooth tip and tooth profile slit of the sub-gear are both chamfered.

[0021] The above scheme, when setting an even number of backlash elimination mechanisms, distributes them in pairs along the same radial line of the planetary carrier. This ensures a uniform distribution of backlash elimination points, avoids concentrated backlash elimination areas, and makes the planetary unit more stable during operation. Chamfering is applied to the tooth tips and sharp angles of the gears to facilitate smoother assembly when the slave gear meshes with the sun gear and ring gear.

[0022] Furthermore, the planetary carrier has a planetary cavity and a planetary bore. The planetary shaft extends into the planetary cavity through the planetary bore, and both the planetary gear and the sub-gear are located within the planetary cavity. The outer diameter of the elastic element is larger than the inner diameter of the sub-gear, and the inner diameter of the elastic element is smaller than the outer diameter of the second support member.

[0023] The above solution: The elastic element with an outer diameter larger than the inner diameter of the sub-gear and an inner diameter smaller than the outer diameter of the second support can effectively separate the sub-gear and the second support in the planetary cavity, thus confining the sub-gear and the second support within the operating area.

[0024] Furthermore, planetary gaskets are provided between the planetary gear and the sub-gear and the top wall and bottom wall of the planetary cavity, and between the planetary gear and the sub-gear and the elastic element.

[0025] The above solution reduces friction between planetary gears and sub-gears and the top and bottom walls of the planetary cavity, as well as between planetary gears and sub-gears and elastic components, thereby reducing frictional heat generation and energy loss.

[0026] Furthermore, the misalignment angle between the relative teeth of the sub-gear of the backlash elimination mechanism when it is not meshing with the sun gear and the ring gear is greater than the misalignment angle between the relative teeth when it is meshing with the sun gear and the ring gear;

[0027] When the sub-gear of the backlash elimination mechanism is not engaged with the sun gear and the ring gear, the elastic element does not apply a preload to the limiting portion of the sub-gear end face; when the sub-gear of the backlash elimination mechanism is engaged with the sun gear and the ring gear, the elastic element applies a preload to the limiting portion of the sub-gear end face.

[0028] The above scheme: the misalignment angle between the sub-gears in the assembled state is reduced, the elastic element deforms, and the sub-gears receive the restoring force after the elastic element deforms, which applies a preload force to the meshing sun gear and gear ring tooth groove; thus effectively eliminating the gap between the sub-gear and the tooth groove; and the deformation of the elastic element can adapt to the impact vibration in the planetary unit process, causing the misalignment angle of each tooth between the sub-gears to float, thereby reducing the wear between the sub-gear and the sun gear and gear ring tooth groove.

[0029] Furthermore, the planetary shaft includes a fixed section and a connecting section, the connecting section being located between the fixed sections, the outer diameter of the connecting section being smaller than the outer diameter of the fixed section, the fixed section being fixedly connected to the planetary bore, and a portion of the fixed section extending into the planetary cavity;

[0030] The connecting section has a snap-fit ​​part on its side wall, and the connecting section is fitted with an elastic sleeve. The elastic sleeve is made of elastic steel and has a conical spiral volute structure. The diameter and length of the elastic sleeve change synchronously with its deformation.

[0031] The inner wall surface of the elastic sleeve is provided with snap grooves corresponding to the position and number of the snap-fit ​​parts. The snap-fit ​​parts are engaged in the snap grooves and fixedly connected to the snap grooves. The outer wall surface of the elastic sleeve is provided with limit protrusions. The inner side wall of the second support member is provided with limit grooves corresponding to the position and number of the limit protrusions. The limit protrusions are engaged in the limit grooves and are clearance-fitted with the limit grooves. When the elastic sleeve is not deformed, its maximum outer diameter is greater than or equal to the outer diameter of the fixed section. The second support member is partially sleeved on the fixed section extending into the planetary cavity and is clearance-fitted with the fixed section.

[0032] The above scheme: The fixed section is used to fix the planetary shaft to the planetary carrier, and the connecting section is used to fix the elastic sleeve. The elastic sleeve has a conical spiral scroll structure, and its diameter and length change synchronously with its deformation. That is, when the elastic sleeve is subjected to radial compression, its diameter changes, and its axial length changes synchronously; correspondingly, its diameter changes synchronously when its axial length changes; and the amount of diameter change is proportional to the amount of length change. In this scheme, the elastic sleeve is designed as a conical spiral scroll structure in which the axial length decreases synchronously when the diameter decreases, and the axial length increases synchronously when the diameter increases.

[0033] The second support component in the assembled state is supported by the fixed section of the planetary shaft and the outer wall of the elastic sleeve. Since the maximum outer diameter of the elastic sleeve when it is not deformed is greater than or equal to the outer diameter of the fixed section, the second support component can float slightly within the gap range between it and the fixed section when subjected to impact vibration. Furthermore, gaps are reserved between the second support component and the top and bottom of the planetary cavity as well as the elastic component. When planetary washers are used, there is a gap between the second support component and the planetary washers. Through the above-mentioned structural design of reserving gaps, the load distribution of the sub-gears can be achieved when the planetary unit is running.

[0034] The backlash elimination mechanism is more susceptible to impact vibration during planetary unit operation, primarily originating from the moment the planetary gears engage and disengage with the sun gear and ring gear. The impact vibration experienced by the slave gear can be broadly categorized into axial and radial vibrations. When the slave gear experiences axial impact vibration, the second support member is rubbed and floats axially due to the axial impact vibration of the slave gear. The inner wall of the elastic sleeve remains relatively fixed, while the outer wall of the elastic sleeve deforms synchronously with the second support member due to the limiting protrusion engaging in the limiting groove. This provides a restoring force in the floating direction of the second support member, thus damping the vibration and preventing axial impact vibration from developing into radial impact vibration, thereby improving the stability of the backlash elimination mechanism.

[0035] When the slave gear is subjected to radial impact vibration, the second support transmits the impact vibration to the elastic sleeve. As the diameter of the elastic sleeve decreases, its axial length also decreases. First, the wound elastic sleeve provides a reverse restoring force to the second support, acting as a damping agent to prevent radial impact vibration from developing into axial impact vibration, thus improving the stability of the backlash elimination structure. Second, due to the reduced axial length of the elastic sleeve, adjacent second supports move closer to each other towards the elastic element between them. Through the friction between the second support and the slave gear, the tendency of the slave gear to move towards the planetary carrier is reduced, thereby reducing the tendency for the slave gear to transmit radial impact vibration to the planetary carrier, further improving the overall stability of the planetary unit during operation. Simultaneously, it prevents excessive increase in the gap between the slave gear and the elastic element, and between the second support and the elastic element, due to impact vibration. It also prevents the elastic element from moving significantly between the second support and the slave gear, reducing frictional heat and wear between the end sidewall of the elastic element and the sidewall of the limiting part, allowing the preload performance of the elastic element to be maintained for a long time and extending the service life of the backlash elimination mechanism.

[0036] Furthermore, the snap-fit ​​parts are staggered on the side wall of the connecting section; the limiting protrusions are distributed at different heights on the side wall of the elastic sleeve, and the projections of the limiting protrusions on the cross-section of the elastic sleeve are located on the same radial line.

[0037] The above solution: By interlocking the buckle parts with the buckle grooves, the inner ring of the elastic sleeve can be stably fixed; the limiting protrusions are distributed at different heights along the same diameter of the elastic sleeve, and each limiting protrusion acts on a second support member. When lateral impact vibration occurs, the inner ring of the elastic sleeve is relatively fixed, and the outer ring of the elastic sleeve is relatively rolled up, reducing the diameter and axial length, thereby providing an effective shock absorption and reset function.

[0038] The beneficial effects of this invention are:

[0039] By incorporating a backlash elimination mechanism on at least one planetary shaft, comprising at least two sub-gears and an elastic element positioned between them, the elastic element creates a misalignment angle between the sub-gears. This allows the sub-gears to contact both sides of the tooth groove when meshing with the sun gear and ring gear, thereby eliminating meshing backlash. This structure not only improves the positioning accuracy and commutation smoothness of the planetary reducer but also reduces impact and wear through the flexible floating characteristics of the elastic element, enhancing long-term reliability. Furthermore, by incorporating limiting parts, arc-shaped surface and arc-groove fits, planetary gaskets, and a special elastic sleeve structure, the installation stability, vibration damping performance, and load-sharing capacity of the backlash elimination mechanism are optimized, effectively extending the service life of the planetary unit. Attached Figure Description

[0040] Figure 1 This is an overall isometric view of the embodiment;

[0041] Figure 2 This is an overall exploded view of the embodiment;

[0042] Figure 3 This is a partial cross-sectional view of an embodiment;

[0043] Figure 4 This is a schematic diagram showing the arrangement of the two backlash elimination mechanisms in an embodiment;

[0044] Figure 5 A partial cross-sectional view of the planetary shaft fitted with an elastic sleeve according to an embodiment;

[0045] Figure 6 The planetary shaft and elastic sleeve are shown in the embodiment.

[0046] Figure 7 An exploded view of the planetary shaft and elastic sleeve as an example;

[0047] Figure 8 An isometric view of the elastic sleeve in the embodiment;

[0048] Figure 9 A cross-sectional view of the elastic sleeve in the embodiment;

[0049] Figure 10 This is a schematic diagram illustrating the deformation principle of the elastic sleeve in an embodiment.

[0050] The reference numerals in the accompanying drawings include:

[0051] 11. Planet carrier; 12. Planet shaft; 13. Planet gear; 14. Planetary cavity; 15. First support member;

[0052] 21. Sub-gear; 22. Elastic element; 23. Second support element; 24. Elastic sleeve; 25. Limiting protrusion; 26. Buckling part; 27. Buckling groove. Detailed Implementation

[0053] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0054] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0055] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0056] The following detailed description illustrates the specific implementation method:

[0057] Example 1: As Figures 1-3 As shown, this embodiment provides a planetary unit with a backlash-eliminating structure. The planetary unit includes a planet carrier 11, within which a plurality of planet shafts 12 are disposed. An input space for accommodating the sun gear is provided in the center of the planet carrier 11. Specifically, the planet carrier 11 serves as the supporting frame of the entire unit and is typically made of cast steel or aluminum alloy to balance structural strength and weight. The planet shafts 12 are evenly distributed along the circumference of the planet carrier 11 and are used to mount planet gears 13 or backlash-eliminating mechanisms. The input space is located at the center of the planet carrier 11 and is used to mount the sun gear. The sun gear, as a power input component, has its teeth extending into the input space to mesh with the planet gears 13 or the backlash-eliminating mechanism.

[0058] In this embodiment, at least one planetary axis 12 is provided with a backlash elimination mechanism, and the remaining planetary axes 12 are rotatably connected to planetary gears 13. The number of backlash elimination mechanisms can be set according to actual accuracy requirements. For example, in one embodiment, a backlash elimination mechanism is provided on only one planetary axis 12, and ordinary planetary gears 13 are provided on the remaining planetary axes 12. This layout can significantly improve the positioning accuracy of the planetary carrier 11 when hovering while reducing costs. In another preferred embodiment, backlash elimination mechanisms can be provided on multiple planetary axes 12 to obtain a more balanced backlash elimination effect.

[0059] The backlash elimination mechanism is the core component of this embodiment. The backlash elimination mechanism includes at least two sub-gears 21 rotatably connected to the planetary shaft 12. An elastic element 22 is disposed between the sub-gears 21, with both ends of the elastic element 22 contacting adjacent sub-gears 21 on either side, causing equal misalignment angles between the relative teeth of the sub-gears 21. Specifically, the structure of the sub-gears 21 is similar to that of a common planetary gear 13, both having teeth and mounting holes. In the assembled state, each sub-gear 21 in the same backlash elimination mechanism is coaxially mounted on the planetary shaft 12, and a space is left between the end faces of adjacent sub-gears 21 to accommodate the elastic element 22. In this embodiment, the elastic element 22 can be a helical compression spring, a disc spring, a snap ring, etc. Preferably, the elastic element 22 in this embodiment is a snap ring structure with an opening. The two ends of the elastic element 22 act on adjacent sub-gears 21, causing the adjacent sub-gears 21 to be relatively misaligned, resulting in a certain angle misalignment of the teeth of adjacent sub-gears 21 in the circumferential direction.

[0060] Planetary gear 13 meshes with a sun gear on the side of the backlash elimination mechanism closest to the input space, while a ring gear meshes with the side of the planetary gear 13 and the backlash elimination mechanism furthest from the input space. When the backlash elimination mechanism meshes with the sun gear and ring gear, due to the misalignment angle between the slave gears 21, the teeth of one slave gear 21 will press against one side of the tooth surface of the sun gear and ring gear tooth groove, while the teeth of the other slave gear 21 will press against the other side of the tooth surface of the sun gear and ring gear tooth groove, eliminating backlash during gear meshing. When the sun gear drives the planetary carrier 11 to rotate, the backlash elimination mechanism can drive the planetary carrier 11 to respond quickly without having to overcome backlash before transmitting torque, thus significantly improving the positioning accuracy and commutation smoothness of the planetary reducer. At the same time, the preload provided by the elastic element 22 has a flexible floating characteristic, which can adaptively compensate for gear wear and thermal deformation, ensuring long-term operational reliability.

[0061] Based on the above structure, the connection structure between the planetary gear 13, the sub-gear 21, the elastic element 22, and the planetary shaft 12 was optimized. Specifically, a first support member 15 is provided between the planetary gear 13 and the planetary shaft 12, and the first support member 15 is sleeved on the planetary shaft 12; a second support member 23 is provided between the sub-gear 21 and the planetary shaft 12, and the second support member 23 is sleeved on the planetary shaft 12. The first support member 15 and the second support member 23 are used to support the planetary gear 13 and the sub-gear 21 to rotate smoothly around the planetary shaft 12, while bearing radial loads. This avoids direct friction between the planetary gear 13 and the sub-gear 21 and the planetary shaft 12, extending the overall service life of the planetary unit.

[0062] The first support 15 and the second support 23 can be cylindrical sleeves or needle roller bearings. The specific form of the first support 15 and the second support 23 can be flexibly selected according to the application scenario and cost budget of the planetary unit. For example, in a cost-sensitive application scenario with relatively low load, cylindrical sleeves can be used for the first support 15 and the second support 23. Cylindrical sleeves have a simple structure, are easy to manufacture, and have a large contact area, providing stable radial support and effectively reducing production costs. In another application scenario with extremely high transmission accuracy requirements, high speed, or large load, needle roller bearings are preferred for the first support 15 and the second support 23. Needle roller bearings, by using rolling friction instead of sliding friction, have a very low coefficient of friction and extremely high rotational accuracy, which can significantly reduce the starting torque of the planetary unit, improve transmission efficiency, and reduce heat generation during operation. In this embodiment, the first support 15 is a needle roller bearing, and the second support 23 is a cylindrical sleeve.

[0063] In some other embodiments, a third support is provided between the elastic element 22 and the planetary shaft 12, and the third support is sleeved on the planetary shaft 12; the third support can also be a cylindrical sleeve or a needle roller bearing. The third support is located between the inner ring of the elastic element 22 and the outer wall of the planetary shaft 12. Since the elastic element 22 (such as a snap ring) may undergo radial expansion or slight torsion during deformation, if it directly contacts the planetary shaft 12, it will easily wear down the surface of the planetary shaft 12.

[0064] Based on the above structure, the fit structure between the sub-gear 21 and the elastic element 22 in the backlash elimination mechanism has been further optimized. Specifically, limiting portions are provided on the adjacent end faces of the sub-gears 21, and the limiting portions extend to the area between the two ends of the elastic element 22. A gap is provided between the side walls of the two ends of the elastic element 22 and the side walls of the limiting portions provided on the adjacent end faces of the sub-gears 21. The limiting portions can be specifically constructed as bosses or ribs protruding axially from the end face of the sub-gears 21. The main function of the limiting portions extending to the area between the two ends of the elastic element 22 is to serve as connecting components that form a misalignment between the elastic element 22 and the sub-gears 21. Through the contact and abutment between the elastic element 22 and the limiting portions, the opposing teeth of the adjacent sub-gears 21 form a misalignment angle. The elastic element 22 will deform during the operation of the backlash elimination mechanism to maintain the preload required for the misalignment angle; if the limiting portions and the elastic element 22 are in tight contact without gap, it will be extremely difficult for the elastic element 22 to deform, causing the flexible floating characteristic of the backlash elimination mechanism to fail.

[0065] In some embodiments, the adjacent sidewalls of the limiting part and the elastic member 22 are arc-shaped or flat, and the adjacent sidewalls of the elastic member 22 and the limiting part are flat grooves that match the sidewalls of the limiting part. In this embodiment, the adjacent sidewalls of the limiting part and the elastic member 22 are arc-shaped, and the adjacent sidewalls of the elastic member 22 and the limiting part are arc-shaped grooves that match the sidewalls of the limiting part. During the operation of the backlash elimination mechanism, with the slight change in the misalignment angle between the sub-gears 21, the end of the elastic member 22 will undergo a slight sliding movement relative to the limiting part. Compared to the flat contact surface between the limiting part and the elastic member 22, this sliding will generate greater sliding friction resistance, which may lead to increased wear of the contact surface and thus affect the stability of the preload. At the same time, the arc-shaped groove can also play a guiding role, guiding the elastic member 22 to slide along a predetermined trajectory during deformation, preventing the end of the elastic member 22 from deflecting or dislodging. This improves the response sensitivity and long-term operational reliability of the backlash elimination mechanism.

[0066] Furthermore, the limiting parts extend to the area between the two ends of the elastic element 22, making point contact, line contact, or surface contact with the elastic element 22. Preferably, the limiting parts extend to the area between the two ends of the elastic element 22, making point contact with the elastic element 22. As the backlash elimination mechanism operates and the elastic element 22 wears, the point contact gradually changes to line contact, and then gradually changes to surface contact. As the contact state evolves from point → line → surface, the contact pressure is individually adapted to the backlash elimination mechanism (due to the machining errors of each component, the contact pressure requirements at different positions between the limiting parts of each backlash elimination mechanism and the elastic element 22 are different), and the contact pressure is evenly distributed, which can maintain a stable preload for a long time.

[0067] Based on the above structure, the layout of the backlash elimination mechanism on the planet carrier 11 and the assembly environment inside the planetary unit were optimized. Specifically, an even number of planet shafts 12 are equipped with backlash elimination mechanisms, and these mechanisms are distributed in pairs along the same radial line of the planet carrier 11. Combined with... Figure 4 As shown, when two backlash elimination mechanisms are used, these two mechanisms are mounted on the planetary shafts 12 located at both ends of the same diameter of the planetary carrier 11. The symmetrical arrangement is mainly due to the fact that the sub-gears 21 in the backlash elimination mechanisms will generate additional radial reaction forces on the gear ring and sun gear under the action of the elastic element 22. If the backlash elimination mechanisms are only arranged on one side, the eccentric load that may be generated when the planetary carrier 11 rotates at high speed will lead to increased vibration. By arranging the backlash elimination mechanisms in pairs on the same radial line, the radial forces generated on both sides can cancel each other out, thereby ensuring the force balance of the planetary carrier 11 and improving the smoothness of the planetary unit's operation.

[0068] In this embodiment, chamfers are also provided on the tooth tips and tooth profile slenderness of the sub-gear 21. During the assembly of the backlash elimination mechanism, due to the preload of the elastic element 22, there is a tendency for relative rotation between the sub-gears 21. This causes the teeth of the sub-gears 21 to easily interfere when they are installed into the gear ring or mesh with the sun gear. The chamfers, with guide slopes at the tooth tips and tooth profile slenderness, allow the teeth of the sub-gear 21 to slide more smoothly into the tooth grooves, reducing assembly difficulty and avoiding tooth surface damage caused by assembly.

[0069] The planet carrier 11 has a planetary cavity 14 and a planetary bore. The planet shaft 12 extends into the planetary cavity 14 through the planetary bore. The planetary gear 13 and the sub-gear 21 are both located within the planetary cavity 14. Figure 3 As shown, the planetary cavity 14 provides a stable space for the operation of the planetary gears 13 and the sub-gears 21, while the planetary bore is used to fix and support the planetary shaft 12. To ensure the axial positional stability of each component inside the backlash elimination mechanism, the outer diameter of the elastic element 22 is larger than the inner diameter of the sub-gear 21, and the inner diameter of the elastic element 22 is smaller than the outer diameter of the second support element 23. This dimensional design achieves axial limiting of each component of the backlash elimination mechanism. Specifically, the outer diameter of the elastic element 22 is larger than the inner diameter of the sub-gear 21, so the elastic element 22 cannot pass through the inner hole of the sub-gear 21, thus being confined within the space between the two sub-gears 21; the inner diameter of the elastic element 22 is smaller than the outer diameter of the second support element 23, so the second support element 23 (such as a cylindrical sleeve or needle roller bearing) cannot pass through the inner hole of the elastic element 22, thus limiting the sub-gear 21 axially by the elastic element 22.

[0070] In addition, in some other embodiments, planetary gaskets are provided between the planetary gears 13 and 21 and the top and bottom walls of the planetary cavity 14, and between the planetary gears 13 and 21 and the elastic element 22. When the planetary unit operates at high speed and under heavy load, the planetary gears 13 and 21 are subjected to axial forces, causing relative rotational friction between their sides and the top and bottom walls of the planetary cavity 14. Simultaneously, there is also fretting friction between the 21 and the elastic element 22. This friction not only consumes energy but also generates a large amount of frictional heat, affecting the performance of the planetary unit. By providing planetary gaskets, the coefficient of friction can be effectively reduced, frictional heat generation can be decreased, thereby improving the overall heat dissipation performance and service life of the planetary unit.

[0071] When the backlash elimination mechanism's sub-gear 21 is not meshing with the sun gear and ring gear, the misalignment angle between the relative teeth is greater than when it is meshing with the sun gear and ring gear. In the free state, i.e., before the backlash elimination mechanism is installed in the planetary cavity 14 and meshes with the sun gear and ring gear, the sub-gears 21 are not subjected to the elastic force of the elastic element 22, but only to the opposing and limiting effect of the elastic element 22, resulting in a misalignment angle between the teeth of the sub-gears 21. That is, when the backlash elimination mechanism's sub-gear 21 is not meshing with the sun gear and ring gear, the elastic element 22 does not apply a preload to the limiting portion of the sub-gear 21's end face; when the backlash elimination mechanism's sub-gear 21 meshes with the sun gear and ring gear, the elastic element 22 applies a preload to the limiting portion of the sub-gear 21's end face.

[0072] Through the aforementioned preload design, when the planetary unit is subjected to impact or vibration during operation, the meshing state between the gears will experience slight fluctuations. Because the elastic element 22 consistently applies preload, the sub-gear 21 can absorb these fluctuations through a small relative rotation; that is, the misalignment angle undergoes a slight floating change under the action of the elastic element 22. On the one hand, this ensures that the gears are always in a backlash-free meshing state, avoiding positioning errors caused by rigid impacts; on the other hand, the deformation of the elastic element 22 effectively buffers the impact load, protecting the gear tooth surface and the planetary carrier 11 structure.

[0073] Example 2: Figures 5-9 As shown, this embodiment further optimizes the connection structure between the planetary shaft 12 and the support member based on the above embodiment. An elastic damping structure is introduced to cope with the impact vibration generated by the planetary unit during high-speed, heavy-load operation. Specifically, the planetary shaft 12 includes a fixed section and a connecting section. The connecting section is located between the fixed sections, and its outer diameter is smaller than that of the fixed sections. The fixed sections are fixedly connected to the planetary bores, and part of the fixed section extends into the planetary cavity 14. The fixed sections are mainly used to achieve an interference fit or key connection with the planetary bores on the planetary carrier 11, ensuring that the planetary shaft 12 is fixed on the planetary carrier 11 and providing a stable support foundation for the entire transmission system. The connecting section is located between the two fixed sections, and its outer diameter contracts to form an annular groove structure. This structure is mainly used to install the elastic sleeve 24, providing space for the deformation of the elastic sleeve 24 and preventing interference between the elastic sleeve 24 and the planetary shaft 12 body during deformation.

[0074] The connecting section has a snap-fit ​​part 26 on its side wall, and an elastic sleeve 24 is fitted onto the connecting section. The elastic sleeve 24 is made of elastic steel and has a conical spiral volute structure. The diameter and length of the elastic sleeve 24 change synchronously with its deformation. The elastic sleeve 24 is the core damping element of this embodiment. It is made of elastic steel (such as spring steel, manganese steel, etc.) and has excellent elastic recovery ability and fatigue resistance. The conical spiral volute structure means that the elastic sleeve 24 is not a simple cylindrical sleeve, but is made of a metal strip spirally wound, and the diameter changes regularly during the winding process (such as gradually increasing or decreasing), and gradually extends to one side, forming a shape similar to a conical spring. When the elastic sleeve 24 of the conical spiral volute structure of this embodiment is subjected to radial compression, the diameter will decrease, and the number of spiral turns will increase, resulting in a shortening of the axial length; conversely, when it is subjected to axial tension, the axial length will increase, and the diameter will increase synchronously.

[0075] To ensure stable installation of the elastic sleeve 24, the inner wall surface of the elastic sleeve 24 is provided with snap-fit ​​grooves 27 corresponding to the position and number of snap-fit ​​parts 26. The snap-fit ​​parts 26 engage with the snap-fit ​​grooves 27 and are fixedly connected to them. The snap-fit ​​parts 26 can be protrusions or ridges provided on the side wall of the connecting section, while the snap-fit ​​grooves 27 are grooves formed in the inner wall of the elastic sleeve 24. Through the engagement of the protrusions and grooves, the inner ring of the elastic sleeve 24 is circumferentially fixed to the planetary shaft 12, preventing the elastic sleeve 24 from slipping relative to the planetary shaft 12 when rotating with the slave gear 21.

[0076] The outer wall surface of the elastic sleeve 24 is provided with limiting protrusions 25, and the inner side wall of the second support member 23 is provided with limiting grooves corresponding to the position and number of the limiting protrusions 25. The limiting protrusions 25 are engaged in the limiting grooves with a clearance fit. In this embodiment, the elastic sleeve 24 is located between the second support member 23 and the planetary shaft 12. Unlike the fixed connection of the inner ring, the outer ring of the elastic sleeve 24 and the second support member 23 are connected with a clearance fit. This allows the limiting protrusions 25 to have a certain amount of room to move within the limiting grooves, and the second support member 23 is not rigidly fixed to the elastic sleeve 24, but can undergo a slight relative displacement, thereby achieving load sharing of the sub-gear 21.

[0077] In this embodiment, the maximum outer diameter of the elastic sleeve 24 when undeformed is greater than or equal to the outer diameter of the fixed section. The second support member 23 is partially sleeved on the fixed section extending into the planetary cavity 14 and has a clearance fit with the fixed section. Since the maximum outer diameter of the elastic sleeve 24 when undeformed is greater than the outer diameter of the fixed section, when the second support member 23 is sleeved, it is actually supported on the two support surfaces: the end face of the fixed section and the outer surface of the elastic sleeve 24. When subjected to impact, the second support member 23 can compress the elastic sleeve 24, thereby obtaining buffer displacement in the radial and axial directions.

[0078] The vibration reduction principle in this embodiment is combined with Figure 10A detailed explanation follows. During planetary unit operation, the impact vibrations experienced by the backlash elimination mechanism are mainly divided into radial impact and axial impact. When the slave gear 21 is subjected to radial impact (such as instantaneous overload during gear meshing), the impact force is transmitted to the second support member 23 through the slave gear 21, thereby compressing the elastic sleeve 24. Due to the limiting effect of multiple latching parts 26, the elastic sleeve 24 in the area covered by the latching parts 26 is fixed relative to the planetary shaft; and since the inner wall of the second support member 23 and the side wall of the elastic sleeve 24 are both arc-shaped surfaces, when the sub-gear 21 is subjected to radial impact, the force is transmitted to the elastic sleeve 24 through the second support member 23, and the side wall of a sector area of ​​the elastic sleeve 24 is subjected to force; since the elastic sleeve 24 is located inside the second support member 23, the inner wall of the second support member 23 has a limiting effect on the side wall of the elastic sleeve 24; combined with the spiral volute structure of the elastic sleeve 24, it has its own elastic deformation path; so that when the force in the sector area acts on the side wall of the elastic sleeve 24 (i.e., when the sub-gear 21 is subjected to radial force), the movable part of the elastic sleeve 24 (the area of ​​the elastic sleeve 24 not covered by the latching parts 26) is wound up (diameter decreases) based on its own elastic deformation path and the limiting effect of the inner wall of the second support member 23; when the impact force is eliminated, the elastic sleeve 24 naturally resets (diameter recovers).

[0079] Based on the characteristics of the conical spiral volute structure, the diameter of the elastic sleeve 24 decreases under pressure, while its axial length shortens simultaneously. The elastic restoring force generated by the reduced diameter directly resists radial impact; while the shortening of the axial length causes the two adjacent second support members 23 to tend to move closer together, and this axial fretting absorbs some of the impact energy. Simultaneously, due to the buffering effect of the elastic sleeve 24, rigid impacts are prevented from being directly transmitted to the planetary shaft 12 and planetary carrier 11. Taking the stable fixing of the inner ring of the elastic sleeve 24 at points B1, B2, and B3, and the side (mostly radial) impact vibration as an example, the inner ring of the elastic sleeve 24 is relatively fixed, while the outer ring of the elastic sleeve 24 is relatively rolled up, with a reduced diameter and axial length, i.e., a slight downward and upward floating relative to each other. Points A1 and A2 after the outer ring of the elastic sleeve 24 is relatively rolled up can be referenced. Figure 10 As shown on the right.

[0080] When the slave gear 21 is subjected to axial impact (such as the axial component force generated by helical gear transmission), the second support member 23 will cause the elastic sleeve 24 to tend to float axially. Due to the gap between the limiting protrusion 25 and the limiting groove, the second support member 23 can overcome the frictional force of the elastic sleeve 24 and make a small axial displacement. During this process, the elastic sleeve 24 deforms and absorbs energy, providing a restoring force and preventing the second support member 23 from continuing to move axially. Through axial flexible floating, not only is the axial impact mitigated, but the conversion of axial vibration into radial vibration is also avoided, thus improving the stability of the planetary unit operation.

[0081] Based on the above structure, in this embodiment, the snap-fit ​​parts 26 are staggered on the sidewall of the connecting section; the limiting protrusions 25 are distributed at different heights on the sidewall of the elastic sleeve 24, and the projections of the limiting protrusions 25 on the cross-section of the elastic sleeve 24 are located on the same radial line. The staggered distribution of the snap-fit ​​parts 26 (such as being evenly staggered along the circumferential direction) can increase the number of contact points between the inner ring of the elastic sleeve 24 and the planetary shaft 12, improve the stability of the connection, and prevent the elastic sleeve 24 from tilting due to uneven force. The distribution of the limiting protrusions 25 at different heights on the sidewall of the elastic sleeve 24 and on the same radial line of the projection of the cross-section of the elastic sleeve 24 allows the elastic sleeve 24 to retract stably when subjected to radial force, causing the second support members 23 on both sides to tend to move closer to each other, thus improving the stability of the shock absorption effect.

[0082] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A planetary unit with a backlash-free structure, comprising a planet carrier, wherein a plurality of planet shafts are disposed within the planet carrier, and an input space for accommodating a sun gear is provided in the middle of the planet carrier; characterized in that, At least one of the planetary shafts is provided with a backlash elimination mechanism, and the remaining planetary shafts are rotatably connected to planetary gears; The backlash elimination mechanism includes at least two sub-gears rotatably connected to the planetary shaft. An elastic element is provided between the sub-gears, and the two ends of the elastic element contact the adjacent sub-gears on both sides, so that the relative teeth of the sub-gears produce equal misalignment angles. The planetary gears and the backlash elimination mechanism are engaged with a sun gear on the side closer to the input space, and the planetary gears and the backlash elimination mechanism are engaged with a gear ring on the side farther from the input space.

2. The planetary unit with backlash-free structure according to claim 1, characterized in that, A first support member is provided between the planetary gear and the planetary shaft, and the first support member is sleeved on the planetary shaft; a second support member is provided between the sub-gear and the planetary shaft, and the second support member is sleeved on the planetary shaft.

3. The planetary unit with backlash-free structure according to claim 2, characterized in that, The first support member and the second support member are cylindrical sleeves or needle roller bearings.

4. The planetary unit with backlash-free structure according to claim 1, characterized in that, A third support is provided between the elastic element and the planetary shaft, and the third support is sleeved on the planetary shaft; the third support is a cylindrical sleeve or a needle roller bearing.

5. The planetary unit with backlash-free structure according to claim 1, characterized in that, Limiting portions are provided on adjacent end faces between the sub-gears, and the limiting portions extend to the area between the two ends of the elastic member. A gap is provided between the side walls of the two ends of the elastic member and the side walls of the limiting portions provided on the adjacent end faces between the sub-gears.

6. The planetary unit with backlash-free structure according to claim 5, characterized in that, The sidewall adjacent to the limiting part and the elastic member is an arc surface or a plane, and the sidewall adjacent to the elastic member and the limiting part is an arc groove or a plane groove that matches the sidewall of the limiting part. The limiting portion extends to the area between the two ends of the elastic element and makes point contact, line contact, or surface contact with the elastic element.

7. The planetary unit with backlash-free structure according to claim 1, characterized in that, An even number of the planetary axes are provided with backlash elimination mechanisms, and the backlash elimination mechanisms are distributed in pairs on the same radial line of the planet carrier; The tooth tip and tooth profile slit of the sub-gear are both chamfered.

8. The planetary unit with backlash-free structure according to claim 2, characterized in that, The planetary carrier has a planetary cavity and a planetary bore. The planetary shaft extends into the planetary cavity through the planetary bore. The planetary gear and the sub-gear are both located in the planetary cavity. The outer diameter of the elastic element is larger than the inner diameter of the sub-gear, and the inner diameter of the elastic element is smaller than the outer diameter of the second support member.

9. The planetary unit with backlash-free structure according to claim 8, characterized in that, Planetary gaskets are provided between the planetary gear and the sub-gear and the top wall and bottom wall of the planetary cavity, and between the planetary gear and the sub-gear and the elastic element.

10. The planetary unit with backlash-free structure according to claim 9, characterized in that, The misalignment angle between the relative teeth of the sub-gear of the backlash elimination mechanism when it is not meshing with the sun gear and the ring gear is greater than the misalignment angle between the relative teeth when it is meshing with the sun gear and the ring gear; When the sub-gear of the backlash elimination mechanism is not engaged with the sun gear and the ring gear, the elastic element does not apply a preload to the limiting portion of the sub-gear end face; when the sub-gear of the backlash elimination mechanism is engaged with the sun gear and the ring gear, the elastic element applies a preload to the limiting portion of the sub-gear end face.

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