Research On Shape Constrained Nonlinear Torque Characteristics Of Dual Mass Flywheel

Dual-mass flywheel torsional vibration damper is an important component of automotive powertrain, plays a very important role in reducing torsional vibration of vehicle transmission system(driveline) and easing the impact of transmission system, etc. The rationality of its design directly affects the car's comfort and reliability of the components.The current development status and development trend of the dual mass flywheel are systematically researched, and mainly the compact structure and widely used Dual Mass Flywheel-Circumferential Short Spring(DMF-CSS) is studied. A detailed study and analysis on the torque of the DMF-CSS introduced friction are carried out. Based on the analysis of the force at work between the spring seat and flywheel of the DMF-CSS introduced friction, the influences on the friction to the torque and the natural frequency of the equivalent model of DMF-CSS are analyzed. On the basis of the dual mass flywheel for the mechanical properties requirements that low torque small twist angle should have the flexibility to reduce the first-order natural frequency and high-torque big twist angle should have high resistance to torque, enforceability of varying stiffness of DMF-CSS are also studied, and creatively proposes a method to achieve the thought of continuous nonlinear varition stiffness "ideal elastic properties" by changing the type of contact line inside the primary flywheel, and the analysis model is built. The main research as follows:The development of the dual mass flywheel and the existing typical structure of dual mass flywheel and it's characteristics are analyzed, mainly focuses on the current widely used Dual Mass Flywheel-Circumferential Short Spring, analyzed the contact force characteristics of the primary flywheel-type line and spring seat of Dual-Mass Flywheel-Circumferential Short Spring, and comparative analyzed two different situations of the introduction of friction and no friction between the spring seat and the flywheel, and the vary of the force of contact point among the primary flywheel, secondary flywheel and spring seat and the variation of the torque curve characteristics are obtained when the torsion angle increases and decreases in the reverse of the dual-mass flywheel introduced friction by calculating and analyzing,and the torque curve consistent with experimental tests result are obtained.Based of these studies, according to the characteristics of the torque transfer principle of Dual-mass flywheel-Circumferential Short Spring, in order to obtain a "ideal elasticity characteristics" of a continuous nonlinear torque characteristics, a new method by changing the medial line of the primary flywheel to change the transmission torque and the contact force with the spring seat is proposed, that is the primary flywheel nonlinear constraint line model, and the principle method in achieving non-linear constraints profile is studied.In this paper, proposed several different non-linear constraint lines; discussed the different types of curves and equations; analyzed and calculated the contact force characteristics between nonlinear torque characteristics of the new primary flywheel constraints line and the spring seat, obtained force variation of contact point among primary flywheel, secondary flywheel and spring seat when double mass flywheel in the torsion angle increases and decreases based on the new constraints line; derived the dual mass flywheel transmission torque theoretical calculation formula; designed constrain lines parameter, analyzed different torque curve of dual mass flywheel with different primary flywheel constrain line, obtained proper constraints medial line for the primary flywheel.A Computer Aided Design(CAD) software system for the design and analysis of the flywheel new constrain line under the windows environment are designed and developed.For the new structure of the Dual Mass Flywheel-Circumferential Short Spring torsional vibration damper, achieved the characteristics of a low torque small twist angle with high flexibility and high torque big twist angle have a high resistance to torque, also achieved smooth torque characteristics for the torsional damper, and the stiffness can change with road conditions and load, avoided the stiffness jump of the critical position, improved ride comfort and torsional vibration capability.