New clutch oil-pressure establishing method design of PHEVs during mode transition process for transient torsional vibration suppression of planetary power-split system

Abstract

For plug-in hybrid electric vehicles (PHEVs), mode transition might be the most effective way of energy conservation. However, the transient torsional vibration (TTV) during mode transition process, which is unavoidable, usually affect the drive comfort. This paper presents an innovative planetary hybrid power-split system (PHPS), which comprised of an epicyclic gear system, two compact clutches and a wedge brake device, and will been applied Chery PHEVs. First, powertrain vibration during mode transition process, as influenced by dynamic transfer friction torque of clutch, angle-varying mesh stiffness of epicyclic gear and external loads of multi-power sources, are investigated through a nonlinear TTV model. Then, the dynamic equations of mode transition process are established and numerically solved to get TTV response as well as vehicle jerk, and further new clutch oil-pressure establishing method design of PHEVs during mode transition process for relative torsional oscillation suppression of PHPS is presented. At last, bench tests are carried out, and results indicated that the proposed optimization model effectively suppressed PHPS torsional oscillation, vehicle longitudinal jerk, and improved driving smoothness during mode transition process.