Research on Four-bar Linkage with Variable Axis Torsion Spring for Vehicle Latch Lock/Unlock

The paper takes the vehicle side door latch as the research background. Based on the mechanism schematic diagram of the lock/unlock branch mechanism, the installation method of the torsion spring with variable axis is analyzed. The linkage with torsion spring is abstracted as a four-bar linkage with torque in the revolute joint and its kinematic singularity is analyzed. The dynamics model of the mechanism is established and simulated, and the kinematic property of the mechanism under three different operating modes is analyzed. The results show that the deformation and torque of the torsion spring at the singular configuration are the largest when the mechanism moves between the left and right limit blocks, and the fast switching phenomenon occurs when the mechanism reaches the singular configuration. It only takes the mechanism 0.33s to move from the singular configuration to one limit position. This study provides some reference value for the analysis and application of the revolute joint with torsion spring.