1、e power transmission portion of the CTC-CVT. This CTC-CVT is composed of input and output shafts and an intermediate rolling element inscribed between them. The input and output shafts have a concave conical form, and the intermediate rolling element has a convex conical form. An offset of E is give
2、n between the input and output shafts. Traction oil intervenes between the concave cone at the end of each shaft and the convex cone of the intermediate rolling element, and it forms an oil film when a pressing force is applied from the input shaft side. A traction force is produced by the oil film,
3、 and the rotation of the input shaft is transmitted to the output shaft via the intermediate rolling element. Speed changes are effected by changing the contact radius of the intermediate rolling element, and the radius change is in turn effected by translating the intermediate rolling element obliq
4、uely along the cone angle. B. Speed-changing Mechanism The CTC-CVT changes the speed smoothly by translating the intermediate rolling element obliquely along the cone angle. Figure 4 shows the geometry of the power transmission portion. Letting r1 be the corotation radius of the input shaft, r2 be t
5、he corotation radius of the convex cone on the input side, 1 be the angular velocity of the input shaft, and 2 be the angular velocity of the rolling element, then the following relationship is obtained on the input side. 2211 rr= (1) Letting r3 be the corotation radius of the convex cone on the out
6、put side, r4 be the corotation radius of the output shaft, and 3 be the angular velocity of the output shaft, then the following relationship is obtained on the output side. 3423 rr= (2) The reduction ratio, e, is the ratio of the angular velocity of the input shaft to that of the output shaft and i
7、s given by the following equation using Equations 1 and 2. 13 42 3 2 2 1 3 1 rr rr e= (3) If the corotation radii, r1 and r4, of the input and output shafts are equal, the following equation is obtained. 32 rre = (4) If the convex cone is translated, the corotation radii r2 and r3 of the intermediat
8、e rolling element at the points of contact respectively with the input and output shafts change. As shown in Figure 5(a), the reduction ratio is 2.0 if the length of r2 is twice the length of r3. It is 1.0 if the length of r2 is equal to the length of r3 (Figure 5(b). Likewise, the reduction ratio i
9、s 0.5 if the length of r2 is half the length of r3 (Figure 5(c). Thus, when the corotation radii of the intermediate rolling element change, the reduction ratio changes according to Equations 3 and 4. Fig. 3. Schematic of power transmission portion Fig. 4. Geometrical parameters of CTC-CVT III. Desi
10、gn of CTC-CVT Prototype To verify the operation and performance of the CTC- CVT, a CTC-CVT prototype was designed. Figure 6 shows a sectional view of the designed CTC-CVT. Table 1 shows the specifications for the designed CTC-CVT prototype. As a design condition, a motor with a rated capacity of 15
11、kw and a rotational speed of 1500 rpm was used as the input power source. The design was done on the design concept of attaining a prototype with high power transmission efficiency. For changing the speed, a mechanism to translate the r2=2r3 r2=r3 r2=r3/2 12th IFToMM World Congress, Besanon (France)
12、, June18-21, 2007 CK-xxx Fig. 6. Schematic view of CTC-CVT intermediate rolling element along the cone angle by turning a handle was used. Figure 7 shows a schematic of the transmission mechanism. A case supports the intermediate rolling element, and a slider is attached to the case. A groove is cut
13、 in the frame at the same angle as the convex cone. A handle is attached on the top of the case, and turning the handle translates the case along the groove and can effect stepless speed changes. The pressure force necessary for the traction drive is given by the loading cam on the input shaft side.
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