Design of a non circular gear Mechanism with Twice Unequal Amplitude Transmission Ratio

This study proposes a new non–circular gear transmission mechanism with an involute–cycloid composite tooth profile to realize the twice unequal amplitude transmission (In a complete rotation cycle of gear transmission, instantaneous transmission ratio has twice fluctuations obvious with unequal amplitude) of non–circular gears. The twice unequal amplitude transmission ratio curve was designed based on Fourier and polynomial functions, the change law of the Fourier coefficient on the instantaneous transmission ratio(In non-circular gear transmission, the transmission ratio changes with time, and the transmission ratio of non-circular gear should be instantaneous transmission ratio) was analyzed, and the pressure angle and contact ratio of the involute–cycloid composite tooth profile was calculated. The involute–cycloid composite tooth profile non–circular gear was machined by WEDM technology, while its meshing experiment was performed using high-speed camera technology. The results demonstrate that the instantaneous transmission ratio curve value obtained via the high-speed camera experiment was consistent with the simulation value of virtual software. Furthermore, the involute–cycloid composite tooth profile was applied in the seedling pickup mechanism of non–circular gear planetary gear train. The possibility of the application of the involute–cycloid composite tooth profile in the seedling pickup mechanism was verified by comparing the consistency of the theoretical and simulated seedling picking trajectory.

Synthesis of multi-input multi-degree-of-freedom fixed shaft gear transmission configuration for vehicles

The rapid development of dual-clutch transmission (DCT) and hybrid and purely electric vehicles stimulate the researches on multi-input fixed shaft gear transmission mechanisms. The multiple degree-of-freedom (DOF) transmission mechanism can achieve a wider range of speed ratio adjustment and more modes under certain space and weight constraints, which is an ideal choice for multi gear transmission. In this paper, a synthesis method of fixed shaft gear transmission configuration is proposed. Based on the established graph theory model, kinematic characteristics of the fixed shaft gear transmission configuration are studied and the shift sequence is determined. Using these characteristics, a derivation method from the basic configuration to the comprehensive gears and shafts configuration is proposed. Multiple parameters such as the synchronizer arrangement and speed ratios are optimized. Finally, the proposed method is vigorously verified by a seven-speed DCT with four DOFs. This method is comprehensive and systematic in designing fixed shaft gear transmission configurations, which can be applied to DCT, transmissions for parallel hybrid electric vehicles, and to some novel multi-input transmissions.