A Review on Dynamic CVT-IVT Transmissions

Abstract

Currently, continuously variable transmission (CVT) is a topic of special interest as it allows the vehicle to have the engine working at its optimum regime (either minimum or maximum power consumption as required) remaining unaltered despite the changes in speed and the torque required on the drive wheels during operation. There is a particular group of CVTs with special characteristics: dynamic type CVTs. In these, in addition to acting on a control element, as in the rest of the kinematic type transmissions, the gear ratio also depends on the external conditions to which the transmission is subjected, that is, the transmission ratio is also determined by other variables such as the angular velocity of the input shaft and the load torque exerted on the output shaft. This paper reviews the most representative dynamic CVTs and torque converters (TCs) stating the basics of their functioning. The transmissions analyzed correspond to different patents, from one of the first [1] to the most recent [2,3] In addition, a brief description of each mechanism is given based on analytical and computational studies of the most interesting items, analyzing the advantages, disadvantages and deficiencies in the operation. Additionally, this review critically provides a warning regarding the pieces of information and working principles taken for granted.