Abstract The two-stage hydro-mechanical continuously variable transmission can realize continuously variable transmission with large transmission ratio and wide transmission range, reduce the rated power of hydraulic components and improve the whole transmission efficiency. The kinematic characteristics of the transmission mechanism are related to the setting of the working mode and the performance of the whole vehicle. This paper analyzed three types of split and confluence forms of hydro-mechanical continuously variable transmission mechanism: the split-torque confluence-speed type, the split-speed confluence-speed type and the split-speed confluence-torque type. Using the lever method, the influence of the position of external force components on the distribution of mechanical points, the positive and negative phases of hydraulic components and the power split type were studied, and the feasible form of split and confluence of the two-stage hydro-mechanical continuously variable transmission mechanism was obtained. The relationship between the rotation speed of hydraulic components and the output rotation speed in each segment was summarized, and the connection law of the output rotation speed between segments was studied based on the theory of no speed difference range-shift. Through the round-trip change of the positive and negative phases of the hydraulic components, the continuous variable variation of the output rotation speed of the two-stage hydro-mechanical continuous transmission was realized. A simulation platform of ZL50 loader was built, which adopted the hydro-mechanical continuously variable transmission of the split-torque confluence-speed and split-torque confluence-speed. The movement characteristics of the loader under typical V cycle working conditions were simulated, and the output torque and transmission efficiency of the transmission was analyzed. The result verified the correctness of the theoretical analysis result. The research reveals the motion characteristics of the hydro-mechanical continuously variable transmission mechanism and the motion connection law between the segments, which provides a theoretical basis for the design and engineering application of the hydro-mechanical continuously variable transmission mechanism.
Received: 27 November 2019
Published: 28 June 2021
ZHANG Lu, YANG Shu-jun, LI Xue-liang, HAN Bin, PANG Yu. Research on kinematic characteristics of two-stage hydro-mechanical continuously variable transmission mechanism. Chinese Journal of Engineering Design, 2021, 28(3): 268-277.
