To enhance the comprehensive transmission performance of hypoid gears with high reduction ratios, this paper proposed a design method for significantly inclined contact lines based on active tooth surface design technology. Firstly, multiple tooth surface imprints with varying degrees of contact line inclination were preset, with specified values for the semi-major axis of the contact ellipse and the length of the contact trace. The pinion conjugate tooth surface was then modified with a parabolic shape to achieve a tooth surface that meets the preset parameters. Subsequently, by integrating Tooth Contact Analysis (TCA) and Load Tooth Contact Analysis (LTCA) techniques, the amplitude of transmission error (ATE), amplitude of loaded transmission error (ALTE), tooth surface load distribution, root bending stress amplitude, and tooth surface flash temperature amplitude were obtained for each tooth surface. The influence of variations in contact trace length on these performance parameters was then analyzed. Finally, a target modified tooth surface was selected, and its comprehensive performance was analyzed and compared with that of the original tooth surface. A case study demonstrates that for a hypoid gear pair with a gear ratio of 5:75, under conditions of highly inclined contact trace on the tooth surface, a longer contact trace length leads to lower contact stress, as well as reduced root bending stress and flash temperature on the tooth surface. The target tooth surface exhibits weakened edge contact, a 12.0% reduction in maximum root bending stress, more uniform contact stress distribution, and a 6.3% decrease in peak flash temperature. As a result, the scuffing load-carrying capacity is enhanced. Overall, the modified target tooth surface exhibits superior contact performance, better load-carrying capacity, and significantly enhanced comprehensive transmission performance.

Regarding problems such as the contact characteristics being extremely sensitive to installation error and generating vibration and noise caused by improper parameters design of hypoid gears, this paper proposed an optimized design method for gear aimed at reducing sensitivity to installation error. Firstly, it proposed a tooth flank contact characteristics evaluation model considering the installation error, including the variation of contact area, the offset of contact trace center value, and the variation of the conversion point amplitude of the transmission error curve. Then, it proposed a NURBS surface fitting method with reduced parameters and carried out tooth flank contact analysis. The mapping relationships among the installation error, the preset control parameters of tooth flank, the machining parameters of tooth flank and the contact characteristic parameters were established. Continuing, this study elucidated the influence patterns of installation error on tooth flank contact characteristics. It established a comprehensive sensitivity model for individual contact characteristic parameter relative to installation error. Finally, with the lowest sensitivity as the optimization goal, the genetic algorithm was used to optimize the design of the preset parameters of the tooth flank. Taking two typical operation condition as an example, through the comparative analysis of the meshing characteristics before and after optimization, it is found that the sensitivity of the optimized tooth flank contact area, the center point coordinates of the contact trace and the variation of the transmission error to the installation error are reduced. The tooth flank optimization design method proposed in this paper can effectively solve the problem that the tooth flank contact characteristics are extremely sensitive to the installation error, and reduce the vibration and noise in the transmission.

In order to further improve the transmission efficiency of the cycloidal pinwheel reducer, this study conducted in-depth research on the influence of the reducer transmission efficiency. It proposed a calculation model for the transmission efficiency of the cycloidal pinwheel reducer that takes into account changes in design parameters and working condition parameters and optimized the parameters. Firstly, considering the friction force and meshing backlash, the study established a multi-tooth load-bearing contact analysis model of the cycloid pinwheel transmission mechanism, and calculate the meshing force and load distribution pattern of the cycloid pinwheel gear. Then, considering the engagement loss, output loss, bearing loss, lubrication loss and sealing loss, this paper proposed a calculation model for the transmission efficiency of the cycloidal pinwheel reducer, and analyzed the influence of the design parameters and working condition parameters on the transmission efficiency of the cycloidal pinwheel reducer. Research shows that, taking frictional stress into account, rotation speed, load, pin tooth pin radius, pin tooth distribution circle radius, eccentricity, and pin tooth sleeve radius are the main parameters that affect transmission efficiency, followed by the number of pin teeth, pin distribution circle radius, pin radius and cycloid tooth width. Finally, the optimal parameter solution was obtained through a multi-objective optimization analysis of the design parameters with gear strength, gear width, tooth profile shape, inter-tooth clearance and load-bearing capacity as the parameter optimization range, and transmission efficiency and volume as the goals. And then a smaller volume and more efficient cycloidal pinwheel reducer was obtained.