Design criteria of half-toroidal traction drive CVTs (continuously variable power transmission) for automobile use are considered. Three fundamental investigations of rolling fatigue, traction fluid molecular structures and efficiency are performed. Following the prototype test, a dual-cavity CVT for a 3 l passenger car was designed and its performance was tested. The results are summarized. The fatigue index measurement on and beneath the traction surface by means of X-ray diffraction clarifies that the fatigue starts to occur from the surface when the maximum Hertzian pressure is designed to be lower than 2.7 GPa. Traction fluid consisting of alicyclic compounds maintains its initial property after traction tests of 108 cycles at a bulk temperature of 120 deg C. The single-cavity CVT for a 1.5 l passenger car has the maximum efficiency of only 75 %. The analysis of torque loss clarifies the quantitative improvements of the deep groove thrust ball bearings and the balance mechanism of the loading force. A newly designed dual-cavity CVT with speed ratio range of 0.434 to 2.303 and transmission capacity of 200 kW succeeds in achieving a total efficiency of 85 % in the transmitting torque range of 100 N to 300 Nm.
Half-toroidal traction drive continuously variable power transmission for automobiles (traction drive materials, transmission design and efficiency)
Material, Übertragung und Wirkungsgrad eines halbtoroidalen stufenlos regelbaren Fahrzeuggetriebes
1995
6 Seiten, 17 Bilder, 2 Tabellen, 14 Quellen
Article (Journal)
English
Half-toroidal traction-drive continuously variable power transmission
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