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All inertial continuous/infinite variable transmissions (CVT-IVT) need of a rectifier. This is due to the fact that this type of CVT-IVTs should transform, in some way, the ratcheting motion into a unique direction of rotation in order to be transmitted to the kinematic chain of the vehicle transmission system. The choice of the rectifying system and the characteristics of the components heavily depend on the motion to be rectified and on the oscillating mechanism generator. The current rectifier systems included in inertial CVT-IVTs use freewheels to transform the oscillating movement. The use of freewheels has serious limitations for tourism and industrial vehicle applications, regarding the upper bounds of conforming to two working situations: i) high torque at low speed, and ii) high speed at a relatively low torque.

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 present communication summarizes the research aiming to the design of a new prototype of a continuously variable transmission system, which will be used as the gear box in automobiles, motorcycles or any other self-propelled vehicle requiring a variable transmission ratio between the power plant and the live axle. The system includes unidirectional clutches - free wheels - and two epicyclic gear systems. The output velocity, with oscillatory character, common to the “ratcheting drives” systems, presents a period similar to that produced by alternative combustion motors, making this new CVT compatible with automobile applications. The variation of the transmission is linear in all the working range.

This work presents a procedure for estimating the efficiency of a new type of continuously variable transmission [CVT]. It is shown that the analysis of this transmission in steady-state conditions may be reduced to the analysis of its equivalent planetary gear train. This is the planetary gear train that has the same structure as that of the CVT and whose gear ratios have been obtained by averaging the original power and torque equations. The analytical expression of the efficiency can be obtained in a fairly systematic way. Such an expression accounts only for the gear mesh losses.