Effect of longitudinal oscillations of the vehicle body when launch.

Abstract

During the tests of the prospective planetary AT under development, undesirable phenomena was revealed, expressed in longitudinal vibrations of the vehicle body that leads to a decrease in the vehicle's comfort. It was established that such a phenomenon manifests itself when the vehicle starts moving during the slippage of the starting friction control element and stops immediately after the slippage is completed. Existing methods for predicting the comfort of transport vehicles do not take into account the excitation of the mechanical system due to oscillatory processes in the starting friction control elements and the car control systems influence. Dynamic processes are considered for the most part for enabled gears or for transition process during shifting. It is necessary to develop a comprehensive approach to the identified phenomenon that would additionally account for the variable structure of the drivetrain during steady-state and transient operating modes, the inconsistency of vehicle control systems that may generate similar excitation vibrations, and the inherent properties of the mechanical system. The objective of this work is to improve vehicle comfort during launching and to develop scientifically justified methods for eliminating longitudinal-angular oscillations arising from slippage in the control elements of a planetary gearbox. A comprehensive simulation model of the vehicle has been developed and validated, incorporating elements and interactions essential to the studied problem. This model allows for modifying input parameters (compliance, moments of inertia, friction coefficients, etc.), control algorithms, and evaluating the effectiveness of proposed technical solutions. A methodology for road testing has been proposed to identify, reproduce, and study longitudinal-angular oscillations during launching, covering the analysis of parameters characterizing control system performance. A literature review revealed insufficient research on this issue in foreign and especially domestic publications for this transmission type and vehicles with high comfort requirements. The computational and experimental study confirms the hypothesis that longitudinal-angular body oscillations occur during acceleration due to slippage in the starting clutch, particularly as a result of frictional self-oscillations. Potential research directions and solutions to the problem have been outlined. Based on the developed model, it is possible to further effectively study the causes of longitudinal vibrations during launching, related both to the parameters of the disturbance source itself and to the parameters of the vehicle systems.