The CVPST (continuously variable power split transmission) concept is presented in the context of an automotive application. The system consists of a variable pulley system (variator) coupling two of the three rotating elements of a planetary gear train. The main feature of this system is that the variator carries only a fraction of the total power flowing through the transmission, thus increasing the power envelope of the potential engine application. This feature also reduces the power losses associated with power transmission, especially at the low-speed-high-torque modes, while providing continuously variable transmission ratio capability. A term dubbed the 'crossover coefficient' is established which can be used to prescribe both the fraction of total power flowing through the variable element and the velocity ratio span for the transmission. An extension of which can be obtained by means of an external gear box allowing a stepless span in the optimum range of both engine and transmission. An engine-transmission-vehicle diagram is used to illustrate the vehicle velocity trace in relation to the continuously variable transmission diagram and the engine performance map. This diagram illustrates the difference between the typical geared transmission and the CVPST, with emphasis on optimum engine and transmission performance.
An automotive continuously variable power split transmission concept (CVPST)
Konzept eines stufenlos verstellbaren Getriebes mit Energieteilung (CVPST) für Kraftfahrzeuge
1999
7 Seiten, 15 Bilder, 4 Quellen
Aufsatz (Konferenz)
Englisch
A Continuously Variable Power Split Transmission for Automotive Applications
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