Planetary joint device with play reduction

Abstract

A backlash-eliminating planetary joint mechanism and device are disclosed. The backlash-eliminating planetary joint mechanism includes a housing, a sun gear, at least one planet gear, and an internal gear ring. It also includes an internal tooth elastic layer for eliminating meshing backlash between the planet gears and the internal gear ring, and an elastic element that applies a preload to the internal tooth elastic layer. The elastic element is located between the housing and the internal tooth elastic layer, its position relative to the internal gear ring is fixed, and one end of the elastic element is embedded in the internal tooth elastic layer. The internal tooth elastic layer and the internal gear ring are stacked axially. The beneficial effects of this invention are as follows: 1. Eliminates gear meshing backlash in traditional planetary reduction mechanisms, significantly improving transmission accuracy and repeatability; measured backlash can be controlled within 1 arc minute. 2. No modification to the original gear body structure is required, resulting in low modification costs and convenient mass production assembly. 3. Adaptable to various specifications of planetary reduction modules.

Description

Technical Field

[0001] This invention relates to the fields of robotics engineering, precision mechanical transmission devices and reducers, and particularly to a backlash-free planetary joint mechanism and a backlash-free planetary joint device. Background Technology

[0002] Currently, planetary gear reducers are widely used in robot joint modules. Planetary reducers have advantages such as compact structure, large transmission ratio, strong load-bearing capacity, and high coaxiality. However, traditional planetary reducers generally use involute spur gear transmission. Due to gear machining errors, assembly errors, and wear during operation, a small gap, or "backlash," inevitably exists between the gear meshing surfaces. The presence of backlash leads to the following problems: 1. Increased transmission backlash (reverse backlash), reducing the positioning accuracy of the robot end effector; 2. Impact and noise generation in frequent forward and reverse rotation or high dynamic response scenarios; 3. Difficulty in meeting the high-precision control requirements of precision assembly and precision machining. To reduce backlash, existing technologies mainly adopt the following measures: 1. Improving gear machining accuracy (such as gear grinding and honing), but this is costly and time-consuming; 2. Using a double-gear preload structure, but this is complex and increases the size; 3. Using harmonic reducers or cycloidal reducers, but this is costly or limited by hollow shafts.

[0003] Therefore, in view of the shortcomings of the existing technology, there is an urgent need for a backlash-free planetary joint mechanism and a backlash-free planetary joint device to make up for the deficiencies of the existing technology. Summary of the Invention

[0004] The first objective of this invention is to overcome at least one of the shortcomings of the prior art and provide a backlash-free planetary joint mechanism. This backlash-free planetary joint mechanism can achieve zero or extremely low backlash, improving motion accuracy and stability.

[0005] The above-mentioned objectives of the present invention are achieved through the following technical measures: A backlash-eliminating planetary joint mechanism is provided, comprising a housing, a sun gear, at least one planet gear, and an internal gear ring. It further includes an internal gear elastic layer for eliminating meshing backlash between the planet gears and the internal gear ring, and an elastic member for applying a preload force to the internal gear elastic layer. The elastic member is located between the housing and the internal gear elastic layer, is fixed in position relative to the internal gear ring, and one end of the elastic member is embedded in the internal gear elastic layer, which is axially stacked with the internal gear ring.

[0006] When the planetary gears are not installed, the teeth of the inner tooth elastic layer and the teeth of the inner tooth ring are misaligned circumferentially.

[0007] When the planetary gear is assembled, it simultaneously meshes with the internal tooth elastic layer and the internal tooth ring, driving the teeth of the internal tooth elastic layer and the teeth of the internal tooth ring to circumferentially align. The elastic element is compressed and deformed, storing elastic potential energy, and continuously outputting preload force to the internal tooth elastic layer.

[0008] When a tooth gap occurs between the planetary gear (300) and the internal gear ring (400), the elastic element releases elastic potential energy, causing the teeth of the internal tooth elastic layer and the teeth of the internal gear ring to restore their circumferential misalignment, so that the tooth surface of the internal tooth elastic layer is always in close contact with the planetary gear, and the tooth gap is compensated in real time to achieve backlash-free meshing.

[0009] When the planetary gears are not assembled, the teeth of the inner tooth elastic layer that intersect with the teeth of the inner tooth ring are defined as a pair of teeth; in the same pair of teeth, the radial line of the tooth apex of the inner tooth elastic layer is defined as the first baseline; the radial line of the tooth apex of the inner tooth ring is defined as the second baseline, and there is an angle between the first baseline and the second baseline, which is defined as A, and there exists a value of 0.1°≤A≤0.5°.

[0010] Preferably, the aforementioned internal toothed elastic layer is provided with a first slot for embedding the end of the elastic member, and one end of the elastic member is embedded in the first slot.

[0011] The housing is provided with a second slot for embedding one end of the elastic element, and the other end of the elastic element is embedded in the second slot.

[0012] or

[0013] The internal gear ring is provided with a third slot for the end of the elastic element to be inserted, and the other end of the elastic element is inserted into the third slot.

[0014] Preferably, the elastic element is a strip-shaped elastic sheet or a fan-shaped elastic sheet.

[0015] Preferably, the above-mentioned elastic elements are provided in multiple forms, and the multiple elastic elements are evenly arranged around the outer periphery of the inner tooth elastic layer.

[0016] In another preferred embodiment, the elastic element is an annular elastic element, which is sleeved between the housing and the internal toothed elastic layer.

[0017] Preferably, the above-mentioned annular elastic element includes multiple protrusions, which abut against the internal tooth elastic layer.

[0018] Preferably, the material of the above-mentioned elastic element is manganese steel.

[0019] Preferably, the thickness of the elastic element is 0.1 mm to 0.3 mm.

[0020] Preferably, the material of the aforementioned internal tooth elastic layer is the same as the material of the internal tooth ring.

[0021] Preferably, the number of teeth and the module of the internal tooth elastic layer 500 and the internal tooth ring 400 are the same.

[0022] The second objective of this invention is to overcome the shortcomings of existing technologies by providing a backlash-free planetary joint device. This backlash-free planetary joint mechanism can achieve zero or extremely low backlash, improving motion accuracy and stability.

[0023] The above-mentioned objectives of the present invention are achieved through the following technical measures: A backlash-free planetary joint device is provided, comprising at least one stage of a backlash-free planetary joint mechanism as described above.

[0024] The beneficial effects of this invention are as follows: 1. By using elastic plate preload and tooth misalignment design, the gear meshing backlash of traditional planetary reduction mechanisms is eliminated, significantly improving transmission accuracy and repeatability. The measured backlash can be controlled within 1 arc minute. 2. Only an elastic layer and elastic sheet are added to the internal gear ring, without changing the original gear body structure, resulting in low modification cost and convenient mass production assembly; 3. It can be used independently as a single-stage backlash-free planetary joint mechanism or in series combination of multiple-stage backlash-free planetary joint mechanisms, and is compatible with various specifications of planetary reduction modules; 4. Manganese steel elastic components have excellent fatigue resistance and wear resistance, with minimal preload decay over long-term use and stable and durable gap-eliminating performance; 5. Eliminates the reversing impact and vibration caused by backlash, ensuring smooth operation during joint acceleration and deceleration and frequent forward and reverse rotation, and significantly reducing working noise. Attached Figure Description

[0025] The invention will be further described with reference to the accompanying drawings, but the contents of the drawings do not constitute any limitation on the invention.

[0026] Figure 1 This is a schematic diagram of the backlash-free planetary joint mechanism in Example 1.

[0027] Figure 2 for Figure 1 Another perspective diagram.

[0028] Figure 3 This is an exploded view of the backlash-free planetary joint mechanism of Example 1.

[0029] Figure 4 This is a schematic diagram of the internal tooth elastic layer, internal tooth ring, and elastic element.

[0030] Figure 5 for Figure 4Another perspective diagram.

[0031] Figure 6 for Figure 5 A magnified view of the "Z" region in the middle.

[0032] Figure 7 This is a schematic diagram of the backlash-free planetary joint mechanism in Example 2.

[0033] Figure 8 This is a schematic diagram of the backlash-free planetary joint mechanism in Example 3.

[0034] Figure 9 This is a schematic diagram of the backlash-free planetary joint mechanism in Example 4.

[0035] Figure 10 This is a schematic diagram of the elastic element in Example 4.

[0036] Figure 11 This is a schematic diagram of the backlash-free planetary joint device in Example 6.

[0037] exist Figures 1 to 11 This includes: Housing 100, Second slot 110 Sun Gear 200, Planet Gear 300 Internal gear ring 400 Internal tooth elastic layer 500, first slot 510, Elastic element 600, protrusion 610. Detailed Implementation

[0038] The technical solution of the present invention will be further described in conjunction with the following embodiments.

[0039] Example 1

[0040] A backlash-free planetary joint mechanism, such as Figures 1 to 3 As shown, the device includes a housing 100, a sun gear 200, at least one planet gear 300, an internal gear ring 400, an internal gear elastic layer 500 for eliminating meshing backlash between the planet gears 300 and the internal gear ring 400, and an elastic member 600 for applying preload to the internal gear elastic layer 500. The elastic member 600 is located between the housing 100 and the internal gear elastic layer 500, and the position of the elastic member 600 relative to the internal gear ring 400 is fixed. One end of the elastic member 600 is embedded in the internal gear elastic layer 500, and the internal gear elastic layer 500 and the internal gear ring 400 are stacked axially.

[0041] It should be noted that the number of planetary gears 300 can be determined according to the actual situation. Specifically, it can be set to 1, 2, 3, 4, 5, 10, etc. The number of planetary gears 300 is determined by the requirements of load, bearing capacity, torque, coaxiality, etc. In this embodiment, three planetary gears 300 are used as an example to illustrate the present invention.

[0042] When the planetary gear 300 is not installed, the teeth of the internal tooth elastic layer 500 and the teeth of the internal tooth ring 400 are arranged in a circumferentially staggered manner. The elastic element 600 is disposed between the housing 100 and the internal tooth elastic layer 500, and the elastic element 600 abuts against the internal tooth elastic layer 500.

[0043] When the planetary gear 300 is assembled, the planetary gear 300 simultaneously meshes with the internal tooth elastic layer 500 and the internal tooth ring 400, driving the teeth of the internal tooth elastic layer 500 and the teeth of the internal tooth ring 400 to circumferentially align. The elastic element 600 is squeezed and deformed and stores elastic potential energy, continuously outputting preload force to the internal tooth elastic layer 500. When a backlash occurs between the planetary gear 300 and the internal gear ring 400, the elastic element 600 releases elastic potential energy, causing the teeth of the internal gear elastic layer 500 and the teeth of the internal gear ring 400 to return to their circumferential misalignment. Figures 4 to 6 As shown, the tooth surface of the internal tooth elastic layer 500 is always in close contact with the planetary gear 300, and the backlash is compensated in real time to achieve backlash-free meshing.

[0044] When the planetary gear 300 is not assembled, the teeth of the internal elastic layer 500 that intersect with the teeth of the internal gear ring 400 are defined as a pair of teeth; within the same pair of teeth, the radial line of the tooth apex of the internal elastic layer 500 is defined as the first baseline; the radial line of the tooth apex of the internal gear ring 400 is defined as the second baseline. There exists an angle between the first and second baselines, defined as A, where 0.1° ≤ A ≤ 0.5°. Figure 4 This embodiment uses 0.3° as an example.

[0045] It should be noted that the tooth shape and number of teeth of the internal tooth elastic layer 500 and the internal tooth ring 400 are exactly the same. They are stacked axially and the teeth are pre-displaced circumferentially, with the displacement angle A ranging from 0.1° to 0.5° (preferably 0.3° in this embodiment). The planetary gear 300 meshes with both layers of internal teeth simultaneously. Before assembly, the teeth of the internal tooth elastic layer 500 are offset relative to the rigid internal tooth ring 400 by a set angle under the limiting action of the elastic element 600. After the planetary gear 300 is installed, since the planetary gear 300 needs to be fixed in the meshing position after assembly, the planetary gear 300 forces the misaligned teeth of the internal tooth elastic layer 500 to be forcibly aligned and overlapped. This angle difference causes the elastic element 600 to be compressed and undergo elastic deformation and store pre-tightening elastic potential energy. After assembly, the elastic element 600 continuously applies pre-tightening compressive force to the internal tooth elastic layer 500. When gears wear down and develop backlash after a period of operation, the elastic element 600 releases its stored elastic potential energy, pushing the internal tooth elastic layer 500 to compensate for the backlash in real time. This ensures that the tooth surface remains in close contact with the planetary gear 300 during forward and reverse reversal processes, eliminating tooth flank backlash from the meshing side. Furthermore, the misalignment angle range of this invention is precisely controllable, preventing excessive offset from causing tooth jamming or transmission disruption, and also preventing insufficient offset from failing to compensate for machining and assembly backlash, thus achieving minimal backlash transmission.

[0046] It should also be noted that, since the misalignment angle of the internal tooth elastic layer 500 of this invention is only in the range of 0.1° to 0.5°, if the angle is too large, tooth jamming and transmission jamming may occur; if the angle is too small, the preload is insufficient and cannot compensate for backlash. Moreover, within this range, the reverse resistance caused by the misalignment angle is minimal and will not interfere with the normal transmission of the reducer. Even if there is a certain reverse torque, in actual applications, this reverse torque shows that it will not have a significant impact on the normal operation of the planetary gear 300 and can ensure normal operation.

[0047] Furthermore, the tooth misalignment angle A of the present invention can be flexibly set according to the actual working conditions. Specifically, it can be selected within the range of 0.1°, 0.2°, 0.3°, 0.4°, and 0.5°. The value of the angle A is determined based on the tooth gap size, gear module, machining accuracy, load conditions, etc. This embodiment uses 0.3° as an example to illustrate the present invention.

[0048] The internal toothed elastic layer 500 is provided with a first slot 510 for the end of the elastic member 600 to be inserted, and a portion of the elastic member 600 is inserted into the first slot 510. The housing 100 is provided with a second slot 110 for the end of the elastic member 600 to be inserted, and the other end of the elastic member 600 is inserted into the second slot 110.

[0049] It should be noted that the housing 100 and the internal gear ring 400 are fixed or integrally connected. The first slot 510 of the internal gear elastic layer 500 allows one end of the elastic element 600 to be inserted into the first slot 510 for limiting and fixing. Moreover, the second slot 110 of the housing 100 allows the other end of the elastic element 600 to be inserted into the second slot 110 for limiting and fixing. This prevents the elastic element 600 from circumferentially sliding or misaligning during operation, ensuring the long-term stability of the preload position, reliable positioning, convenient assembly, and avoiding the advantage of the elastic element 600 shifting under high-speed reciprocating rotation, which can lead to backlash failure.

[0050] The elastic element 600 is a strip-shaped elastic sheet or a fan-shaped elastic sheet. This embodiment uses a strip-shaped elastic sheet as an example. The material of the elastic element 600 is manganese steel, specifically 65 manganese steel. After heat treatment, the hardness of 65 manganese steel can reach HRC40-50, and the thickness is 0.1-0.3mm, which is adjusted according to the torque.

[0051] It should be noted that the elastic element 600, installed between the housing 100 and the internal tooth elastic layer 500, continuously provides axial preload, applying a continuous compressive force to the internal tooth elastic layer 500, forcing the tooth surface of the internal tooth elastic layer 500 to conform to the planetary gear 300. The manganese steel material exhibits excellent fatigue resistance, wear resistance, and elastic stability. The elastic element 600 has a thin structure, occupying little space, and does not alter the overall dimensions of the original planetary gear system, making it compatible with the standard planetary reducer housing 100. Furthermore, strip-shaped or fan-shaped elastic plates offer advantages such as simple processing, easy disassembly, maintenance, and replacement.

[0052] Multiple elastic elements 600 are provided, and these elastic elements 600 are evenly arranged around the outer periphery of the inner tooth elastic layer 500. The number of elastic elements 600 can be determined according to the actual situation, specifically 2, 3, 4, 6, or an integrated full-circumference annular structure. The number of elastic elements 600 depends on the size of the inner tooth elastic layer 500, the load, the preload requirement, and the installation space. For example, when the diameter or torque of the inner tooth elastic layer 500 is large, the number of elastic elements 600 can be increased, thereby applying a uniform preload pressure to all parts of the circumference of the inner tooth elastic layer 500, ensuring uniform force on the entire tooth surface and eliminating local gaps in the full circumferential meshing. This embodiment uses four strip-shaped elastic plates as an example to illustrate the invention.

[0053] The internal tooth elastic layer 500 is made of the same material as the internal gear ring 400, such as 40Cr or 20CrMnTi, and undergoes carburizing and quenching treatment to ensure the hardness of the tooth surface. The internal tooth elastic layer 500 and the internal gear ring 400 have the same number of teeth and module.

[0054] It should be noted that the internal tooth elastic layer 500 and the internal tooth ring 400 have the same number of teeth and are made of the same material, which ensures that the pitch circles and modules of the two layers of internal teeth are matched. The planetary gear 300 synchronously and smoothly meshes with the two layers of teeth, and the force is evenly distributed. It has the advantages of unified processing benchmark, low production and processing cost, synchronous thermal expansion and contraction deformation, and the misalignment angle is not easily changed under high and low temperature conditions, and the backlash elimination performance is stable.

[0055] The backlash-free planetary joint mechanism of this invention operates on the following principle: When an external motor drives the sun gear 200 to rotate, the sun gear 200 drives the planet gears 300 to revolve and rotate. When there is backlash between the planet gears 300 and the internal gear ring 400, the tooth profiles of the internal gear ring 400 and the internal tooth elastic layer 500 have a circumferential phase offset angle (A) of 0.1° to 0.5°. Under the continuous preload of the elastic element 600, the internal tooth elastic layer 500 always presses against the tooth surface of the planet gear 300. Regardless of whether the rotation is forward or reverse, there is no gap in the meshing, achieving ultra-low backlash transmission. When meshing with the internal tooth elastic layer 500, since the elastic plate always presses the internal tooth elastic layer 500 against the planet gear 300, the meshing surfaces always maintain close contact regardless of whether the planet gear 300 rotates forward or reverse, without generating backlash, thus achieving backlash-free output.

[0056] The assembly method of the backlash-free planetary joint mechanism of the present invention is as follows: 1. Fix the internal gear ring 400 to the inside of the housing 100 with bolts; 2. Insert multiple sets of elastic plates into the second slot 110 of the housing 100 and arrange them evenly along the circumference; 3. Stack the internal gear elastic layer 500 on the end face of the internal gear ring 400, rotate it until the teeth form a preset misalignment angle, and the end of the elastic plate is inserted into the first slot 510 of the internal gear elastic layer 500; 4. Use the pre-tightening effect of the elastic plate to complete the pre-installation limit of the internal gear elastic layer 500; 5. Assemble the sun gear 200, planet gear 300, and planet carrier in sequence according to the conventional planet gear 300 series structure; 6. Check the meshing state of the planet gear 300 and the double-layer internal gear to ensure that there is no visible meshing gap.

[0057] The beneficial effects of this backlash-free planetary joint mechanism are as follows: 1. By using elastic plate preload and tooth profile misalignment design, the gear meshing backlash of traditional planetary reduction mechanisms is eliminated, significantly improving transmission accuracy and repeatability. The measured backlash can be controlled within 1 arc minute. 2. Only an elastic layer and elastic plate are added to the internal gear ring 400, without modifying the original gear body structure, resulting in low modification costs and convenient mass production assembly. 3. It can be used independently as a single-stage backlash-free planetary joint mechanism or in series with multiple stages, adapting to various specifications of planetary reduction modules. 4. The 600 manganese steel elastic component has excellent fatigue resistance and wear resistance, with minimal preload decay over long-term use, ensuring long-lasting and stable backlash-free performance. 5. Eliminating the reversing impact and vibration caused by tooth backlash ensures smooth operation during joint acceleration and deceleration and frequent forward and reverse rotation, significantly reducing working noise.

[0058] Example 2

[0059] A backlash-free planetary joint mechanism, such as Figure 7 As shown, other features are the same as in Embodiment 1, except that: two elastic members 600 are provided, and the internal gear ring 400 is provided with a third slot (not shown in the figure) for the end of the elastic member 600 to be inserted, and the other end of the elastic member 600 is inserted into the third slot.

[0060] The inner toothed elastic layer 500 has a first slot 510, which allows one end of the elastic element 600 to be inserted into the first slot 510 for limiting and fixing. The inner toothed ring 400 has a third slot, which allows the other end of the elastic element 600 to be inserted into the third slot for limiting and fixing. This prevents the elastic element 600 from circumferentially sliding or misaligning during operation, ensures the long-term stability of the preload position, provides reliable positioning and convenient assembly, and avoids the backlash failure caused by the elastic element 600 shifting under high-speed reciprocating rotation.

[0061] Compared to Example 1, this example uses two elastic elements 600 to apply pressure symmetrically at two points, meeting the preload requirements of planetary joints with small to medium load specifications, thus reducing the number of parts. With fewer parts and further simplified assembly processes, it is suitable for small, lightweight micro-robot joints and low-torque reduction modules.

[0062] Example 3

[0063] A backlash-free planetary joint mechanism, such as Figure 8 As shown, the other features are the same as in Embodiment 1, except that the elastic element 600 is a fan-shaped elastic sheet.

[0064] Compared with Example 1, the fan-shaped elastic sheet of this embodiment can better fit the 500 arc surface of the inner tooth elastic layer, and has a larger contact area, lower pressure per unit area, and smoother elastic deformation. Therefore, this embodiment has the advantages of a large force-bearing surface, smoother preload distribution, and less stress fracture of the elastic sheet, making it suitable for medium-to-high load heavy-duty planetary joints.

[0065] Example 4

[0066] A backlash-free planetary joint mechanism, such as Figure 9 and Figure 10 As shown, other features are the same as in Embodiment 1, except that: the elastic element 600 is an annular elastic element 600, which is sleeved between the housing 100 and the inner toothed elastic layer 500.

[0067] The annular elastic element 600 includes multiple protrusions 610, which abut against the internal toothed elastic layer 500.

[0068] Compared to Example 1, the annular elastic element 600 in this example is a one-piece structure with 610 protrusions that concentrate the preload. The annular elastic element 600 can apply pressure continuously and evenly throughout the circumference without any blind spots in segmented pressure application. Moreover, the annular elastic element 600 has a single component, allowing for one-step assembly without the risk of missing or incorrectly assembled small parts; it also offers the highest efficiency for batch assembly.

[0069] Example 5

[0070] A backlash-free planetary joint device includes a set of backlash-free planetary joint mechanisms according to Embodiments 1-4.

[0071] In addition to the backlash-free planetary joint mechanism, the backlash-free planetary joint device of the present invention also includes components that enable the backlash-free planetary joint device to operate normally, such as motors, planetary carriers, output flanges, output shafts, support and positioning, rotation auxiliary components, sealing and lubrication accessories, detection auxiliary optional components, etc. These working components are conventional technical structures known in the field of planetary reducers and are not the focus of the invention. They are only essential components for the mechanism to achieve deceleration, rotation, and load output, and will not be described in detail here.

[0072] The beneficial effects of this backlash-free planetary joint device are as follows: 1. By using elastic plate preload and tooth misalignment design, the gear meshing backlash of traditional planetary reduction mechanisms is eliminated, significantly improving transmission accuracy and repeatability. The measured backlash can be controlled within 1 arc minute. 2. Only an elastic layer and elastic plate are added to the internal gear ring 400, without modifying the original gear body structure, resulting in low modification costs and convenient mass production assembly. 3. It can be used independently as a single-stage backlash-free planetary joint mechanism or in series with multiple stages, adapting to various specifications of planetary reduction modules. 4. The 600 manganese steel elastic component has excellent fatigue resistance and wear resistance, with minimal preload decay over long-term use, ensuring long-lasting and stable backlash-free performance. 5. Eliminating the reversing impact and vibration caused by tooth backlash ensures smooth operation during joint acceleration and deceleration and frequent forward and reverse rotation, significantly reducing working noise.

[0073] Example 6

[0074] A backlash-free planetary joint device, such as Figure 11 As shown, there are multiple backlash-free planetary joint mechanisms including Embodiments 1-4. This embodiment will be specifically described using a two-stage backlash-free planetary joint mechanism as an example.

[0075] Based on Embodiment 5, this embodiment of the backlash-eliminating planetary joint device adds another backlash-eliminating planetary joint mechanism, defining the two mechanisms as a primary backlash-eliminating planetary joint mechanism and a secondary backlash-eliminating planetary joint mechanism. In this backlash-eliminating planetary joint device, the planet carrier in the primary backlash-eliminating planetary joint mechanism is coaxially fixed with the sun gear 200 of the secondary backlash-eliminating planetary joint mechanism. The two mechanisms in this embodiment operate independently, working together to eliminate backlash in the entire transmission chain.

[0076] In addition to the backlash-free planetary joint mechanism, the backlash-free planetary joint device of the present invention also includes components that enable the backlash-free planetary joint device to operate normally, such as motors, planetary carriers, output flanges, output shafts, support and positioning, rotation auxiliary components, sealing and lubrication accessories, detection auxiliary optional components, etc. These working components are conventional technical structures known in the field of planetary reducers and are not the focus of the invention. They are only essential components for the mechanism to achieve deceleration, rotation, and load output, and will not be described in detail here.

[0077] Compared with Example 5, the backlash-free planetary joint device in this example uses a multi-stage backlash-free planetary joint mechanism for deceleration, which has good versatility and scalability.

[0078] Example 7

[0079] An application of the backlash-free planetary joint mechanism in Embodiments 1-4 or Embodiments 5 and 6, wherein the backlash-free planetary joint mechanism is applied to the joint of a robot.

[0080] Because this backlash-free planetary joint mechanism can achieve planetary deceleration with zero or minimal backlash, it only requires adding an elastic layer and elastic sheet to the internal gear ring 400 without altering the original planetary deceleration main structure. This improves the motion accuracy and stability of the robot joint without significantly increasing cost or volume.

[0081] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A backlash-free planetary joint mechanism, comprising a housing (100), a sun gear (200), at least one planet gear (300), and an internal gear ring (400), characterized in that: It also includes an internal tooth elastic layer (500) for eliminating meshing backlash between the planetary gear (300) and the internal gear ring (400), and an elastic element (600) for applying preload to the internal tooth elastic layer (500). The elastic element (600) is located between the housing (100) and the internal tooth elastic layer (500). The position of the elastic element (600) relative to the internal gear ring (400) is fixed, and one end of the elastic element (600) is embedded in the internal tooth elastic layer (500). The internal tooth elastic layer (500) and the internal gear ring (400) are stacked axially. When the planetary gear (300) is not installed, the teeth of the internal tooth elastic layer (500) and the teeth of the internal tooth ring (400) are arranged in a circumferentially misaligned manner; When the planetary gear (300) is assembled, the planetary gear drives the teeth of the internal tooth elastic layer (500) and the teeth of the internal tooth ring (400) to circumferentially align. The elastic element (600) is squeezed and deformed and stores elastic potential energy, continuously outputting preload force to the internal tooth elastic layer (500). When a tooth gap appears between the planetary gear (300) and the internal gear ring (400), the elastic element (600) releases elastic potential energy, causing the teeth of the internal tooth elastic layer (500) and the teeth of the internal gear ring (400) to return to their circumferential misalignment, so that the tooth surface of the internal tooth elastic layer (500) is always in close contact with the planetary gear (300).

2. The backlash-free planetary joint mechanism according to claim 1, characterized in that: When the planetary gear (300) is not assembled, the teeth of the internal tooth elastic layer (500) that intersect with the teeth of the internal tooth ring (400) are defined as a pair of teeth; In the same pair of teeth, the radial line of the tooth apex of the inner tooth elastic layer (500) is defined as the first baseline; The radial line of the tooth apex of the internal gear ring (400) is defined as the second baseline; There is an angle between the first baseline and the second baseline, which is defined as A, and has a range of 0.1°≤A≤0.5°.

3. The backlash-free planetary joint mechanism according to claim 1, characterized in that: The internal toothed elastic layer (500) is provided with a first slot (510) for the end of the elastic member (600) to be inserted, and one end of the elastic member (600) is inserted into the first slot (510).

4. The backlash-free planetary joint mechanism according to claim 1, characterized in that: The housing (100) is provided with a second slot (110) for inserting one end of the elastic member (600), and the other end of the elastic member (600) is inserted into the second slot (110). or The internal gear ring (400) is provided with a third slot for the end of the elastic member (600) to be inserted, and the other end of the elastic member (600) is inserted into the third slot.

5. The backlash-free planetary joint mechanism according to claim 1, characterized in that: The elastic element (600) is a strip-shaped elastic sheet or a fan-shaped elastic sheet; The elastic element (600) is provided in multiple ways, and the multiple elastic elements (600) are evenly arranged around the outer periphery of the inner tooth elastic layer (500) along the circumference.

6. The backlash-free planetary joint mechanism according to claim 1, characterized in that: The elastic element (600) is an annular elastic element (600), and the annular elastic element (600) is sleeved between the housing (100) and the internal toothed elastic layer (500); The annular elastic element (600) includes multiple protrusions (610), which abut against the internal toothed elastic layer (500).

7. The backlash-free planetary joint mechanism according to any one of claims 1-6, characterized in that: The elastic element (600) is made of manganese steel.

8. The backlash-free planetary joint mechanism according to any one of claims 1-6, characterized in that: The thickness of the elastic element (600) is 0.1 mm to 0.3 mm; The material of the internal tooth elastic layer (500) is the same as that of the internal tooth ring (400).

9. The backlash-free planetary joint mechanism according to any one of claims 1-6, characterized in that: The number of teeth and the module of the internal tooth elastic layer (500) and the internal tooth ring (400) are the same.

10. A backlash-free planetary joint device, characterized in that: It includes at least one level of the backlash-free planetary joint mechanism as described in any one of claims 1 to 9.

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