Research on Star Gear Matching Method for RV Reducer
RV reducers have been widely used in precision instruments, aerospace, defense, industrial robots, medical devices, and other fields due to their large transmission ratio, high torsional stiffness, high transmission accuracy, high power density, strong impact resistance, long service life, and adjustable backlash.

RV transmission originated from traditional cycloidal pinwheel planetary transmission, which is a new type of two-stage closed type differential planetary transmission with few teeth. Industry scholars have long conducted basic research on this topic. In terms of gear matching for RV transmission, Zhao Haiming et al. proposed a gear matching method that changes the phase angle between the internal spline and external teeth of the spur gear. Gao Wenming and others proposed a new gear matching condition for RV reducers - interchangeability condition. Han Linshan and others analyzed the gear matching method of RV reducers. The above studies are all based on gear transmission with a specific number of teeth, and cannot achieve gear matching for gears with any number of teeth.  

Based on the meshing principle of planetary gears, the author establishes the gear matching model of RV reducer row stars, puts forward the gear matching method of RV reducer row stars meeting different models and transmission ratios, and verifies its correctness through RV-80E-120 reducer and newly developed RV-3000J reducer.  

RV reducers have been widely used in precision instruments, aerospace, defense, industrial robots, medical devices, and other fields due to their large transmission ratio, high torsional stiffness, high transmission accuracy, high power density, strong impact resistance, long service life, and adjustable backlash. RV transmission originated from traditional cycloidal pinwheel planetary transmission, which is a new type of two-stage closed type differential planetary transmission with few teeth. Industry scholars have long conducted basic research on this topic. In terms of gear matching for RV transmission, Zhao Haiming et al. proposed a gear matching method that changes the phase angle between the internal spline and external teeth of the spur gear. Gao Wenming and others proposed a new gear matching condition for RV reducers - interchangeability condition. Han Linshan and others analyzed the gear matching method of RV reducers. The above studies are all based on gear transmission with a specific number of teeth, and cannot achieve gear matching for gears with any number of teeth.  

Based on the meshing principle of planetary gears, the author establishes the gear matching model of RV reducer row stars, puts forward the gear matching method of RV reducer row stars meeting different models and transmission ratios, and verifies its correctness through RV-80E-120 reducer and newly developed RV-3000J reducer.  

The RV reducer is a closed differential gear system consisting of a first stage involute gear planetary transmission mechanism and a second stage cycloidal pin gear planetary transmission mechanism

Using a combination of parallel four-bar linkage mechanism and gear mechanism to achieve transmission. The first stage transmission includes a sun gear that meshes with each other and two or more planetary gears, which are fixedly mounted on parallel crankshafts. In the second stage cycloidal transmission, the crankshaft and the planetary gear are fixed together through splines. The cycloidal gear is installed on two eccentric cam shafts with a phase difference of 180 ° between the crankshaft. When the reducer is running, the planetary gear drives the cycloidal gear to move in an eccentric plane through the crankshaft and forms a small tooth difference mesh with the needle pin.  

From the perspective of composition, the RV reducer belongs to the 2KV planetary mechanism, which is composed of a combination of KHV and 2KV planetary transmissions. K represents the center wheel, V represents the output shaft, and H represents the planetary carrier. The RV reducer structure consists of the sun gear, needle gear housing, and a planetary carrier as the basic components, with a 2KH transmission structure. Analysis of the internal transmission structure reveals that the transmission structure belongs to the KHV type, which simply converts the original single arm center input into two or three evenly distributed arm inputs.

During the transmission process, the motor drives the sun gear to rotate clockwise. The sun gear meshes with the planetary gear to distribute power to the double crank mechanism, achieving synchronous input and overcoming the dead point of the dual phase parallel double crank mechanism, completing the first stage of deceleration. The planetary gear revolves around the axis of the gear shaft while rotating counterclockwise. The planetary gear is fixedly connected to the crankshaft and serves as the second stage input. The cycloidal gear is driven by the hyperbolic shaft to engage with the needle gear pin for eccentric planar motion. At this time, the cycloidal gear rotates around its own axis while revolving around the axis of the needle gear housing, and the output planetary carrier is driven by the hyperbolic shaft to achieve power convergence.