A continuously variable transmission (CVT) that maintains the engine in its optimum power range has the potential to solve two issues of fuel economy and tail-pipe emissions. In 1999, a traction-drive half-toroidal CVT was commercialized for a large-displacement engine in front-engine rear-drive vehicle. In response to recently growing requirements for higher torque capacity in a more compact design, the authors have suggested that one way to increase torque capacity by 50% is to use six power rollers in a double-cavity CVT. Consequently; development of a six-power-roller CVT was initiated in 2000. This variator provides the following technical benefits and features. First, since torque capacity increases by 1.5 times in simple calculation, the transmission becomes more compact compared to a transmission of the same torque capacity. Second, it becomes easier to mount the transmission in the floor tunnel space of a front-engine rear-drive vehicle because of changing the cross-sectional shape from rectangular to circular. Third, reduced elastic deformation of the discs is achieved by increasing the number of contact points between each power roller and input/output disc from two to three. In this paper, experiments on a prototype confirmed the possibility of a six-power-roller variator developed for the purpose of further increasing transmission torque capacity up to 430 Nm as opposed to a current four-power-roller, and further simplifying the speed-ratio control system. Technical advancements include: confirmation of synchronization and stability of six power rollers; establishment of a cost-effective speed-ratio control system using a small three-port electro-hydraulic pressure proportional valve; replacement of the hydro-mechanical servomechanism with a simplified sensorless control system.


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    Title :

    Efficiency and stability of the six power-roller half-toroidal variator with 430 Nm torque capacity


    Additional title:

    Wirkungsgrad und Stabilität eines Halbtoroidvariatorgetriebes mit sechs Reibrädern und einer Drehmomentleistung von 430 Nm


    Contributors:


    Publication date :

    2006


    Size :

    12 Seiten, 22 Bilder, 1 Tabelle, 7 Quellen


    Type of media :

    Conference paper


    Type of material :

    Storage medium


    Language :

    English






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