# Design and Analysis of Internal-External Composite Meshing Hy-Vo Chain
## 1 Introduction
Therefore, the design approach and characteristics of the internal-external composite meshing mechanism of the Hy-Vo chain are worthy of deeper study. Recently, scholars have been more inclined to research the NVH characteristics of round pin jointed silent chain drive systems. [PERSON] et al. [14] investigated the relations between the meshing angles and the chain transverse vibrations and tensile forces and proved the dynamics performance of a silent chain transmission system could be significantly improved by slightly adjusting the meshing angles. [PERSON] et al. [15] proposed a new type of roller chain for a specific conveyor to reduce the operation noise and analyzed its noise characteristics by conducting experiments. [PERSON] et al. [16] studied the pressure, thickness, and temperature rise for an oil film in the contact area between the round pin and the chain hole and developed the model from the perspective of stable-state thermal elastohydrodynamic lubrication by using Ree-Eyring fluid. [PERSON] et al. [17] studied the noise performance of the silent chain drive in cab motorcycles by analyzing the order and the time frequency and analyzed the noise mechanism and the main problems causing noise. [PERSON] et al. [18] investigated the fatigue life distribution of silent chain based on the fatigue reliability of a specific silent chain product CL04T-9 and established the relations between the fatigue life and the load level. [PERSON] et al. [19; 20] analyzed the frictional characteristics between a material named PA46 polyamide and the roller chain and silent chain, obtaining the effects of velocity, tension force, chain pitch, and temperature on the frictional losses of the chain system. [PERSON] [21] analyzed the influence of rotational speed on friction losses with temperature in a silent chain drive system. Obviously, if the design approach and meshing characteristics of the internal-external composite meshing Hy-Vo chain can be obtained, the NVH characteristics of the silent chain drive system will be further enhanced by the achievements of the above research. In this research, we proposed the design approach and the meshing characteristics for the internal-external composite meshing Hy-Vo chain, which cannot be obtained by using the classical meshing theory. Firstly, we built the Hy-Vo chain meshing system and deeply analyzed the difference between the meshing of the chain-sprocket and the meshing of gears. Secondly, by rigidifying the external meshing Hy-Vo chain as a rack, we analyzed the fluctuation range of the pitch line of the external meshing Hy-Vo chain. Based on the relationship between the actual chain pitch line and the rigid chain pitch line, we deduced the function of the internal meshing profile for the internal-external composite meshing Hy-Vo chain system and analyzed its meshing characteristics. Thirdly, we conducted comparative multi-body dynamics experiments. The results show that the design approach of the internal-external composite meshing Hy-Vo chain proposed in this study is effective and feasible, and the internal-external composite meshing characteristics in the classical meshing theory are not completely correct. Compared with the existing Hy-Vo chain types, as for the internal-external composite meshing Hy-Vo chain designed by the new method proposed in this study, the system polygon action, the system meshing performance, and the system transmission stability can all be significantly improved, thus making Hy-Vo chain applicable to the transmission field with more stringent working conditions. At the same time, there is no obvious evidence to show that the internal-external composite meshing mechanism can reduce meshing impacts.