Low-cost high-load robot joint reducer structure

Abstract

The application belongs to the technical field of joint speed reducer, and provides a low-cost high-bearing robot joint speed reducer structure, which comprises a shell, the inside of the shell is provided with a speed reduction assembly, a four-point contact ball bearing is arranged between the outer wall of the output end of the speed reduction assembly and the inner wall of the shell, a pre-tightening assembly for applying axial pre-tightening force to the bearing inner ring in the four-point contact ball bearing is arranged between the four-point contact ball bearing and the output end of the speed reduction assembly, the pre-tightening assembly is arranged between the two-stage planet carrier and the bearing inner ring, the bearing inner ring is continuously applied with axial pre-tightening force, the axial play caused by temperature change, load fluctuation or long-term wear is compensated in real time, the four-point contact ball bearing always maintains the four-point contact state under the conditions of positive and negative rotation and variable load of the robot joint, and the speed reducer has stable radial, axial and overturning stiffness.

Description

Technical Field

[0001] This invention relates to the field of joint reducer technology, and in particular to a low-cost, high-load-bearing robot joint reducer structure. Background Technology

[0002] Industrial robot joint reducers are core components of robot motion control, and their performance directly affects the robot's positioning accuracy, load-bearing capacity, and service life. Currently, most mainstream robot joint reducers (such as RV reducers, harmonic reducers, and two-stage planetary reducers) use crossed roller bearings as the main support bearings at their output ends. Crossed roller bearings can simultaneously withstand radial loads, bidirectional axial loads, and overturning moments, and have the advantages of high rigidity and high precision.

[0003] However, crossed roller bearings have the following drawbacks in practical applications: First, the raceway precision grinding process of crossed roller bearings is complex, the assembly of the rollers and cage is difficult, and the requirements for material heat treatment and machining accuracy are extremely high, resulting in high manufacturing costs. Second, the preload and coaxiality of crossed roller bearings need to be strictly controlled during assembly, the assembly tooling is complex, and the assembly efficiency is low. Third, when crossed roller bearings wear or fail, replacing the bearing requires disassembling the entire planetary transmission mechanism of the reducer, resulting in long maintenance cycles and high repair costs.

[0004] To reduce costs and simplify structure, existing technologies employ four-point contact ball bearings. These solutions integrate the bearing raceway onto the planetary carrier or housing, resulting in an integrated structure with significant drawbacks: the bearing raceway and planetary carrier are machined as a single unit, requiring extremely high precision in heat treatment and machining of the base material; once the raceway wears, the entire planetary carrier must be replaced, leading to high maintenance costs; the integrated structure cannot use standardized bearing assemblies, resulting in poor versatility; furthermore, this type of solution does not consider the axial clearance issue caused by changes in contact angle under forward / reverse rotation and variable load conditions, leading to a decrease in stiffness after long-term use and affecting transmission accuracy.

[0005] To address this, a low-cost, high-load-bearing robot joint reducer structure is proposed. Summary of the Invention

[0006] The purpose of this invention is to provide a low-cost, high-load-bearing robot joint reducer structure to solve the problems of high manufacturing cost and difficult assembly and maintenance of existing crossed roller bearings, as well as the high replacement cost after wear and the lack of a dynamic compensation mechanism for axial clearance in existing integrated four-point contact ball bearing solutions.

[0007] To achieve the above objectives, the main technical solutions adopted by the present invention include: A low-cost, high-load-bearing robot joint reducer structure includes a housing, a reduction assembly is disposed inside the housing, a four-point contact ball bearing is disposed between the outer wall of the output end of the reduction assembly and the inner wall of the housing, and a preload assembly for applying axial preload force to the inner ring of the four-point contact ball bearing is disposed between the four-point contact ball bearing and the output end of the reduction assembly.

[0008] In a low-cost, high-load-bearing robot joint reducer structure according to the present invention, the reduction assembly includes a primary planetary gear assembly and a secondary planetary gear assembly; The first-stage planetary gear assembly includes a first internal gear ring, a first-stage planetary carrier, and an input shaft. The first internal gear ring is fixedly installed inside the housing. A first sun gear is fixedly sleeved on the input shaft. The first-stage planetary carrier is disposed inside the first internal gear ring. A first planetary gear is rotatably mounted on the first-stage planetary carrier. The first planetary gear meshes with both the first sun gear and the first internal gear ring. The secondary planetary gear assembly includes a second internal gear ring, a secondary planetary carrier, and a second input shaft. The second input shaft is fixedly connected to the output end of the primary planetary carrier. The second internal gear ring is fixedly installed inside the housing. The secondary planetary carrier is located inside the second internal gear ring. A second planetary gear is rotatably mounted on the secondary planetary carrier. A second sun gear is fixedly sleeved on the second input shaft. The second planetary gear meshes with both the second sun gear and the second internal gear ring. The inner ring of the bearing is sleeved on the secondary planetary carrier.

[0009] In a low-cost, high-load-bearing robot joint reducer structure according to the present invention, the preload assembly is a disc spring, which is disposed between the secondary planetary carrier and the inner ring of the bearing.

[0010] In a low-cost, high-load-bearing robot joint reducer structure according to the present invention, an annular limiting protrusion is fixedly connected to the outer wall of the end of the secondary planetary carrier away from the input shaft, an annular groove is formed on the inner wall of the bearing inner ring, one end of the disc spring abuts against the annular limiting protrusion, and the other end of the disc spring abuts against the annular groove.

[0011] In a low-cost, high-load-bearing robot joint reducer structure according to the present invention, a first limiting groove is provided on the outer wall of the secondary planetary carrier, and a second limiting groove corresponding to the first limiting groove is provided on the inner wall of the bearing inner ring. After the bearing inner ring is fitted onto the secondary planetary carrier, the first limiting groove and the second limiting groove form a limiting cavity, and a limiting block is provided in the limiting cavity.

[0012] In a low-cost, high-load-bearing robot joint reducer structure according to the present invention, the outer ring of the four-point contact ball bearing is interference-fitted with the inner wall of the housing.

[0013] In a low-cost, high-load-bearing robot joint reducer structure according to the present invention, an end cap is fixedly mounted on one end of the housing near the four-point contact ball bearing by a first screw, and one side of the end cap abuts against one side of the outer ring of the bearing.

[0014] In a low-cost, high-load-bearing robot joint reducer structure according to the present invention, a dust cover is fixedly installed at one end of the secondary planetary carrier near the end cover by a second screw.

[0015] In a low-cost, high-load-bearing robot joint reducer structure according to the present invention, an annular first step is provided on the inner side of the end cover, and an annular second step is provided on the outer edge of the dust cover. The first step and the second step are staggered to form a labyrinth sealing structure.

[0016] In a low-cost, high-load-bearing robot joint reducer structure according to the present invention, a sealing cap is provided between the outer ring of the bearing and the inner ring of the bearing.

[0017] This invention has at least the following beneficial effects: By setting a preload assembly between the secondary planetary carrier and the inner ring of the bearing, a continuous axial preload is applied to the inner ring of the bearing, which compensates in real time for axial clearance caused by temperature changes, load fluctuations or long-term wear. This ensures that the four-point contact ball bearing always maintains a four-point contact state under the forward and reverse rotation of the robot joint and variable load conditions, and ensures that the reducer has stable radial, axial and overturning stiffness.

[0018] With independent four-point contact ball bearings, along with detachable end caps and dust covers, the primary and secondary planetary gear assemblies do not need to be disassembled when replacing the bearings. This avoids the problem of having to replace the entire planetary carrier after the raceway of an integrated structure wears out, significantly reducing maintenance downtime and lowering the total life cycle cost. Attached Figure Description

[0019] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a cross-sectional structural diagram of the present invention; Figure 3 for Figure 2 A magnified structural diagram of part A in the diagram; Figure 4 This is a schematic diagram of the exploded structure of the present invention; Figure 5 This is a schematic diagram of the structure of the secondary planetary carrier of the present invention; Figure 6 This is a schematic diagram of the structure of the four-point contact ball bearing of the present invention.

[0020] Explanation of icon numbers: 1. Housing; 2. Reduction assembly; 201. First internal gear ring; 202. First-stage planetary carrier; 2021. First planetary gear; 203. Input shaft; 2031. First sun gear; 204. Second internal gear ring; 205. Second-stage planetary carrier; 2051. Second planetary gear; 2052. Annular limiting protrusion; 2053. First limiting groove; 206. Second input shaft; 2061. Second sun gear; 3. Four-point contact ball bearing; 301. Bearing outer ring; 302. Bearing inner ring; 3021. Annular groove; 3022. Second limiting groove; 303. Sealing cover; 4. End cover; 401. First step; 5. Dust cover; 501. Second step; 6. Limiting block; 7. Preload assembly. Detailed Implementation

[0021] The following will describe in detail the implementation of this application with reference to the accompanying drawings and embodiments, so that the implementation process of how this application uses technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly.

[0022] Please refer to Figures 1 to 6 As shown, an embodiment of the present invention provides a low-cost, high-load-bearing robot joint reducer structure, including a housing 1, a reduction assembly 2 disposed inside the housing 1, a four-point contact ball bearing 3 disposed between the outer wall of the output end of the reduction assembly 2 and the inner wall of the housing 1, and a preload assembly 7 disposed between the four-point contact ball bearing 3 and the output end of the reduction assembly 2 for applying axial preload force to the inner ring 302 of the four-point contact ball bearing 3.

[0023] By adopting the above technical solution, the housing 1 provides support and protection for the entire reducer, and the reduction assembly 2 converts the input high-speed, low-torque into low-speed, high-torque output from its output end. The four-point contact ball bearing 3 is located between the outer wall of the output end and the inner wall of the housing 1, bearing the radial force, bidirectional axial force, and overturning moment at the output end. The preload assembly 7 is installed between the four-point contact ball bearing 3 and the output end of the reduction assembly 2, applying axial preload to the inner ring 302 of the bearing, eliminating internal clearance, improving bearing rigidity, and ensuring that the balls and raceways always maintain a four-point contact state under forward and reverse operating conditions, thereby improving the transmission accuracy and load-bearing stability of the reducer.

[0024] In this embodiment, the reduction assembly 2 includes a first-stage planetary gear assembly and a second-stage planetary gear assembly; The first-stage gear assembly includes a first internal gear ring 201, a first-stage planetary carrier 202, and an input shaft 203. The first internal gear ring 201 is fixedly installed inside the housing 1. A first sun gear 2031 is fixedly sleeved on the input shaft 203. The first-stage planetary carrier 202 is located inside the first internal gear ring 201. A first planetary gear 2021 is rotatably mounted on the first-stage planetary carrier 202. The first planetary gear 2021 meshes with both the first sun gear 2031 and the first internal gear ring 201. The second-stage planetary gear assembly includes a second internal gear ring 204, a second-stage planetary carrier 205, and a second input shaft 206. The second input shaft 206 is fixedly connected to the output end of the first-stage planetary carrier 202. The second internal gear ring 204 is fixedly installed inside the housing 1. The second-stage planetary carrier 205 is located inside the second internal gear ring 204. A second planetary gear 2051 is rotatably mounted on the second-stage planetary carrier 205. A second sun gear 2061 is fixedly sleeved on the second input shaft 206. The second planetary gear 2051 meshes with both the second sun gear 2061 and the second internal gear ring 204. The inner ring of the bearing 302 is sleeved on the second-stage planetary carrier 205.

[0025] By adopting the above technical solution, power is transmitted through the input shaft 203, driving the first sun gear 2031 to rotate. The first sun gear 2031 drives the first planetary gear 2021 to revolve within the first internal gear ring 201, driving the first-stage planetary carrier 202 to output at a lower speed. The output end of the first-stage planetary carrier 202 transmits power to the second sun gear 2061 through the second input shaft 206. The second sun gear 2061 drives the second planetary gear 2051 to revolve within the second internal gear ring 204, driving the second-stage planetary carrier 205 to output at an even lower speed. The bearing inner ring 302 is fitted onto the second-stage planetary carrier 205, which is the output end of the reduction assembly 2. Through two-stage planetary reduction, a large reduction ratio and high output torque are obtained, while maintaining a compact coaxial output structure.

[0026] In this embodiment, the preload assembly 7 is a disc spring, which is disposed between the secondary planetary carrier 205 and the bearing inner ring 302.

[0027] By adopting the above technical solution, a disc spring is installed as a preload component 7 between the secondary planetary carrier 205 and the bearing inner ring 302. The disc spring features low compression height, high elastic stiffness, and stable force, making it suitable for applications with limited axial space. When the secondary planetary carrier 205 and the bearing inner ring 302 tend to move axially relative to each other, the disc spring generates a reaction force, maintaining axial compression on the bearing inner ring 302, eliminating gaps caused by temperature changes or wear, and maintaining the preload state of the four-point contact ball bearing 3.

[0028] Disc springs can be single-piece, multi-piece paired, or stacked to adjust the preload and stiffness characteristics. Paired springs stacked in the same direction increase the compression stroke, while stacked springs stacked in opposite directions increase the preload. The specifications and combination of disc springs are selected based on the reducer's rated load and bearing specifications. During assembly, the preload is controlled between 5% and 15% of the bearing's rated dynamic load by measuring the compression.

[0029] In this embodiment, an annular limiting protrusion 2052 is fixedly connected to the outer wall of the end of the secondary planetary carrier 205 away from the input shaft 203, and an annular groove 3021 is opened on the inner wall of the bearing inner ring 302. One end of the disc spring abuts against the annular limiting protrusion 2052, and the other end of the disc spring abuts against the annular groove 3021.

[0030] By adopting the above technical solution, the annular limiting protrusion 2052 is fixed to the outer wall of the secondary planetary carrier 205, serving as an axial stop on one side of the disc spring. An annular groove 3021 is formed in the inner wall of the bearing inner ring 302, and the side wall of the annular groove 3021 near the bearing raceway serves as an axial stop on the other side of the disc spring. The disc spring is compressed between the annular limiting protrusion 2052 and the side wall of the annular groove 3021. The disc spring is completely accommodated within the thickness range of the bearing inner ring 302, saving axial space.

[0031] In this embodiment, a first limiting groove 2053 is provided on the outer wall of the secondary planetary carrier 205, and a second limiting groove 3022 corresponding to the first limiting groove 2053 is provided on the inner wall of the bearing inner ring 302. After the bearing inner ring 302 is fitted onto the secondary planetary carrier 205, the first limiting groove 2053 and the second limiting groove 3022 form a limiting cavity, and a limiting block 6 is provided in the limiting cavity.

[0032] By adopting the above technical solution, a first limiting groove 2053 is formed on the outer wall of the secondary planetary carrier 205, and a second limiting groove 3022 is formed on the corresponding position of the inner wall of the bearing inner ring 302. When the bearing inner ring 302 is fitted onto the secondary planetary carrier 205, the two grooves align to form a closed limiting cavity. The limiting block 6 is embedded in this limiting cavity to restrict the relative circumferential rotation between the secondary planetary carrier 205 and the bearing inner ring 302, while allowing the two to retain the small axial relative displacement required by the design, so that the disc spring can work normally. The limiting block 6 undertakes the function of torque transmission or anti-rotation, preventing relative sliding or wear between the bearing inner ring 302 and the secondary planetary carrier 205 under frequent forward and reverse impacts.

[0033] In this embodiment, the outer ring 301 of the four-point contact ball bearing 3 is interference-fitted with the inner wall of the housing 1.

[0034] By adopting the above technical solution, the outer ring 301 of the bearing is interference-fitted with the inner wall of the housing 1, which firmly fixes the outer ring 301 of the bearing to the housing 1, bears the radial load and overturning moment transmitted from the inner ring 302 of the bearing, and transmits the load to the housing 1. The interference fit ensures that the outer ring 301 of the bearing will not rotate relative to the housing 1 or move axially, thereby improving the support rigidity.

[0035] Furthermore, an end cap 4 is fixedly installed on one end of the housing 1 near the four-point contact ball bearing 3 by a first screw, and one side of the end cap 4 abuts against one side of the outer ring 301 of the bearing.

[0036] By adopting the above technical solution, the end cover 4 is fixed to the end face of the housing 1 by the first screw, and the inner end face of the end cover 4 directly abuts against one side end face of the bearing outer ring 301. The end cover 4 further restricts the axial displacement of the bearing outer ring 301, and together with the interference fit of the inner wall of the housing 1, ensures that the bearing outer ring 301 is reliably positioned in both the axial and radial directions. The end cover 4 is removable, which facilitates the removal of the outer ring when replacing the bearing.

[0037] In this embodiment, a dust cover 5 is fixedly installed on one end of the secondary planetary carrier 205 near the end cover 4 by a second screw.

[0038] By adopting the above technical solution, the dust cover 5 is fixedly installed at the end of the secondary planetary carrier 205 by the second screw, and rotates together with the secondary planetary carrier 205. The dust cover 5 covers the outside of the bearing to prevent dust, chips and other foreign objects from entering the bearing area from the output shaft end.

[0039] Furthermore, the inner side of the end cap 4 is provided with an annular first step 401, and the outer edge of the dust cover 5 is provided with an annular second step 501. The first step 401 and the second step 501 are arranged alternately to form a labyrinth sealing structure.

[0040] By adopting the above technical solution, the annular first step 401 on the inner side of the end cover 4 and the annular second step 501 on the outer edge of the dust cover 5 interlock radially and axially, forming a tortuous labyrinthine channel. When external impurities or moisture attempt to enter the bearing area, they must pass through multiple right-angle turns in the labyrinthine gaps and be blocked by centrifugal force and flow resistance. Suitable for high-speed rotation or dusty environments.

[0041] In this embodiment, a sealing cap 303 is provided between the outer ring 301 and the inner ring 302 of the bearing.

[0042] By adopting the above technical solution, the sealing cover 303 is installed in the annular space between the outer ring 301 and the inner ring 302 of the bearing, typically located on one or both sides of the bearing's axial direction. The sealing cover 303 is a contact-type seal integrated into the four-point contact ball bearing 3, such as a rubber lip seal or a steel dust cover, used to seal the internal raceway space of the bearing, prevent grease leakage, and prevent external microparticles from entering the raceway. The sealing cover 303, together with the labyrinth seal, forms a double seal, greatly improving the bearing's reliability in harsh environments.

[0043] The axial preload applied by the preload assembly 7 to the bearing inner ring 302 satisfies the following dynamic compensation equation: ; in: The amount of axial force change that needs to be compensated for by the preload assembly (unit: N). A positive value indicates that the preload needs to be increased, and a negative value indicates that the preload needs to be decreased. The wear compensation coefficient for the reducer (unit: N / cycle) is determined by the stiffness of the disc spring and the average wear depth per unit cycle. The number of forward and reverse reversal cycles for the robot joints is accumulated (dimensionless). The thermal deformation compensation coefficient of the reducer (unit: N / K) is determined by the stiffness of the disc spring, the difference in thermal expansion coefficients between the planetary carrier and the inner ring of the bearing, and the effective length in the preload direction. This refers to the temperature change inside the reducer relative to the assembly reference temperature (unit: K).

[0044] The derivation process is as follows: 1. Physical background: During long-term forward and reverse rotation of robot joints, the increase in axial clearance of four-point contact ball bearings mainly stems from two independent physical mechanisms: Wear mechanism: Fretting wear between the inner ring of the bearing and the planetary carrier mating surface, and between the raceway and the balls, causes the axial clearance to accumulate linearly with the number of reversals, thereby reducing the preload.

[0045] Thermal deformation mechanism: The thermal expansion coefficients of the secondary planetary carrier and the inner ring of the bearing are different. When the temperature changes, the axial deformation of the two is inconsistent, which changes the compression of the disc spring and thus causes a change in the preload.

[0046] 2. Derivation of the wear term: Let the average wear depth caused by each unit of reversing cycle be... (Unit: m / cycle), then the total wear depth is: ; Wear increases the preload path length, which is equivalent to a decrease in the compression of the disc spring. According to Hooke's Law, the reduction in preload is: ; in This refers to the axial stiffness of the disc spring (or other preloaded elastic element) (unit: N / m). Let... If the unit is N / cycle, then: .

[0047] A positive value indicates that additional preload is required to compensate for wear.

[0048] 3. Derivation of the heat distortion term: Define the difference in thermal expansion coefficients: ; in The coefficient of thermal expansion of the secondary planetary carrier material 205 is... The coefficient of thermal expansion of the 302 material in the bearing inner ring (unit: ).

[0049] When the temperature rises hour: like (If the planetary carrier expands more than the inner ring of the bearing), then the planetary carrier will extend towards the bearing relative to the inner ring of the bearing, further compressing the disc spring and increasing the preload. like If this happens, the preload will decrease.

[0050] The relative axial deformation difference is: ; in This is the effective length in the preload direction (unit: m). This deformation directly translates into a change in the compression of the disc spring, resulting in a natural change in the preload force: ; make If the unit is N / K, then: ; Notice: when , hour, This indicates that the preload automatically increases, therefore the system should reduce external compensation, i.e., the compensation term should be negative; Therefore, the actual amount of force change that needs to be actively adjusted by the preload assembly is: .

[0051] 4. Superposition principle: The total axial force change that needs to be compensated is the algebraic sum of wear compensation and thermal compensation: ; Substituting, we get: .

[0052] The equation has a clear physical meaning: wear always requires an increase in preload, while thermal effects may increase or decrease the preload, and the final compensation is the difference between the two.

[0053] Example: Suppose a robot joint reducer is operating under the following conditions: Disc spring stiffness N / m; Average wear depth per unit cycle m / cycle; Total number of forward and reverse commutations ; Planetary carrier material: aluminum alloy ; Bearing inner ring material GCr15: ; but ; Effective length in preload direction m; Temperature rise K; calculate: Wear compensation coefficient N / cycle; Wear and tear items: N; thermal deformation compensation coefficient N / K; Heat distortion term: N; Total compensation: N.

[0054] The results show that thermal deformation caused the preload to increase naturally by 13.75 N, which exceeds the 10 N required to compensate for wear. Therefore, the preload needs to be reduced by about 3.75 N to maintain the optimal preload.

[0055] If the material selection makes (For example, if the planetary carrier is made of carbon fiber composite material and the bearing inner ring is made of steel), then the thermal deformation compensation coefficient is negative, that is: ; Substituting, we get: .

[0056] At this point, the thermal effect causes the preload to decrease, requiring additional compensation.

[0057] Parameter description table: Technical effects: Combined with the records of the robot controller The actual measurement with the temperature sensor It can calculate in real time It drives an active preload adjustment mechanism (such as piezoelectric ceramics, electromagnetic push rods, or adjustable disc springs) to achieve closed-loop precise control of the preload force.

[0058] This ensures that the four-point contact ball bearing is always in the optimal preload condition throughout its entire lifespan, avoiding fatigue pitting caused by excessive preload or increased vibration and wear caused by insufficient preload.

[0059] Wear prediction based on the cumulative number of commutations can provide early warnings before reaching a set threshold, enabling predictive maintenance and avoiding sudden failures.

[0060] Working principle and process: 1. Initialization: After the reducer is assembled, the wear compensation coefficient is measured on the test bench. Calibration test; measurement of disc spring stiffness Effective length in the pre-tightening direction Determine the difference in the coefficients of thermal expansion of the materials by referring to the table. Calculate the thermal deformation compensation coefficient .

[0061] 2. Real-time monitoring: The robot controller accumulates the number of forward and reverse direction reversals. A temperature sensor (embedded in the housing or bearing outer ring) reads the current temperature and calculates the temperature relative to the assembly reference temperature. .

[0062] 3. Compensation Calculation: Substitute the values ​​into the equation using the microprocessor or embedded system: This gives the additional axial force that needs to be applied.

[0063] 4. Execute adjustment: If The active preload mechanism outputs a preload force to increase stress; if This reduces the preload.

[0064] 5. Closed-loop stability: Repeat steps 2-4 at regular intervals (e.g., every 1000 cycles or every 1°C temperature rise) to form a dynamic equilibrium.

[0065] 6. Lifespan warning: When When the maximum compensation range allowed by the design is exceeded, the system will issue a maintenance alarm, prompting the bearing to be replaced or recalibrated.

[0066] In summary, the working principle of this application is as follows: Power is input through the input shaft 203, and after two stages of reduction via the primary and secondary planetary gear assemblies, low-speed, high-torque output is achieved by the secondary planetary carrier 205. The output torque is transmitted to the inner ring 302 of the bearing via the limit block 6, and then to the outer ring 301 and housing 1 via the rolling elements. During this process, the disc spring continuously applies axial preload to the inner ring 302 of the bearing, compensating for clearance caused by temperature changes or wear, ensuring that the four-point contact ball bearing 3 is always in a state of zero clearance or slight negative clearance, thereby maintaining high rigidity and high transmission accuracy. The labyrinth seal and the bearing's own sealing cover 303 work together to prevent the intrusion of external contaminants, ensuring long-term reliable operation of the bearing.

[0067] The foregoing description illustrates and describes several preferred embodiments of the present invention. However, as previously stated, it should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the inventive concept by means of the foregoing teachings or techniques or knowledge in related fields. Any modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A robot joint reducer system, characterized in that, The device includes a housing (1), inside which a speed reduction assembly (2) is disposed. A four-point contact ball bearing (3) is disposed between the outer wall of the output end of the speed reduction assembly (2) and the inner wall of the housing (1). A preload assembly (7) for applying axial preload force to the inner ring (302) of the four-point contact ball bearing (3) is disposed between the four-point contact ball bearing (3) and the output end of the speed reduction assembly (2). The preload assembly (7) is a disc spring. The axial preload applied by the preload assembly (7) to the bearing inner ring (302) satisfies the following dynamic compensation equation: ,in, This represents the amount of axial force variation that needs to be compensated for by the preload assembly. A positive value indicates that the preload needs to be increased, while a negative value indicates that the preload needs to be decreased. The wear compensation coefficient of the reducer is determined by the stiffness of the disc spring and the average wear depth per unit cycle. Accumulate the number of forward and reverse direction switching cycles for the robot joints; The thermal deformation compensation coefficient of the reducer is determined by the stiffness of the disc spring, the difference in thermal expansion coefficients between the planetary carrier and the inner ring of the bearing, and the effective length in the preload direction. This refers to the temperature change inside the reducer relative to the assembly reference temperature. The control system performs the following steps: Step 1: Real-time monitoring: The robot controller accumulates the number of forward and reverse switching cycles Ncycle; the temperature sensor reads the current temperature and calculates ΔT relative to the assembly reference temperature; Step 2, Compensation Calculation: Substitute the equation into the embedded system: This yields the additional axial force that needs to be applied. Step 3, Perform adjustment: If The active preload mechanism outputs a preload force to increase stress; if This reduces the preload; Step 4, Closed-loop stabilization: Repeat steps 1-3 at set intervals to form a dynamic equilibrium; Step 5, Lifespan Warning: When When the maximum compensation range allowed by the design is exceeded, the system will issue a maintenance alarm, prompting the bearing to be replaced or recalibrated.

2. The robot joint reducer system according to claim 1, characterized in that: The reduction assembly (2) includes a first-stage planetary gear assembly and a second-stage planetary gear assembly; The first-stage planetary gear assembly includes a first internal gear ring (201), a first-stage planetary carrier (202), and an input shaft (203). The first internal gear ring (201) is fixedly installed inside the housing (1). A first sun gear (2031) is fixedly sleeved on the input shaft (203). The first-stage planetary carrier (202) is located inside the first internal gear ring (201). A first planetary gear (2021) is rotatably mounted on the first-stage planetary carrier (202). The first planetary gear (2021) meshes with both the first sun gear (2031) and the first internal gear ring (201). The secondary planetary gear assembly includes a second internal gear ring (204), a secondary planetary carrier (205), and a second input shaft (206). The second input shaft (206) is fixedly connected to the output end of the primary planetary carrier (202). The second internal gear ring (204) is fixedly installed inside the housing (1). The secondary planetary carrier (205) is located inside the second internal gear ring (204). A second planetary gear (2051) is rotatably mounted on the secondary planetary carrier (205). A second sun gear (2061) is fixedly sleeved on the second input shaft (206). The second planetary gear (2051) meshes with both the second sun gear (2061) and the second internal gear ring (204). The bearing inner ring (302) is sleeved on the secondary planetary carrier (205).

3. A robot joint reducer system according to claim 2, characterized in that: The disc spring is disposed between the secondary planetary carrier (205) and the inner ring (302) of the bearing.

4. A robot joint reducer system according to claim 3, characterized in that: An annular limiting protrusion (2052) is fixedly connected to the outer wall of the end of the secondary planetary carrier (205) away from the input shaft (203). An annular groove (3021) is opened on the inner wall of the bearing inner ring (302). One end of the disc spring abuts against the annular limiting protrusion (2052), and the other end of the disc spring abuts against the annular groove (3021).

5. A robot joint reducer system according to claim 2, characterized in that: The outer wall of the secondary planetary carrier (205) is provided with a first limiting groove (2053), and the inner wall of the bearing inner ring (302) is provided with a second limiting groove (3022) corresponding to the first limiting groove (2053). After the bearing inner ring (302) is fitted onto the secondary planetary carrier (205), the first limiting groove (2053) and the second limiting groove (3022) form a limiting cavity, and a limiting block (6) is provided in the limiting cavity.

6. A robot joint reducer system according to claim 2, characterized in that: The outer ring (301) of the four-point contact ball bearing (3) is interference-fitted with the inner wall of the housing (1).

7. A robot joint reducer system according to claim 6, characterized in that: An end cap (4) is fixedly installed on one end of the housing (1) near the four-point contact ball bearing (3) by a first screw, and one side of the end cap (4) abuts against one side of the outer ring (301) of the bearing.

8. A robot joint reducer system according to claim 7, characterized in that: A dust cover (5) is fixedly installed on one end of the secondary planetary carrier (205) near the end cap (4) by a second screw.

9. A robot joint reducer system according to claim 8, characterized in that: The inner side of the end cap (4) is provided with an annular first step (401), and the outer edge of the dust cover (5) is provided with an annular second step (501). The first step (401) and the second step (501) are arranged alternately to form a labyrinth sealing structure.

10. A robot joint reducer system according to claim 6, characterized in that: A sealing cap (303) is provided between the outer ring (301) and the inner ring (302) of the bearing.

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