Electrical power generation devices that use lead zirconate titanate piezoelectric (PZT) elements have been developed to convert structural vibration energy into electrical energy. We have reported the effects of vibration loads on the power-generation characteristics of a PZT element doped with niobium (Nb), and have proposed the use of laminated PZT elements to significantly improve the power-generation characteristics of PZT elements. In this study, we have made three-layer, five-layer and seven-layer PZT elements. In the experimental study, the effects of the number of layers of the laminated PZT element, the loads and frequencies of the powergeneration characteristics of the laminated PZT element are evaluated by vibration tests. The results indicated that the maximum electric power of a seven-layer PZT test piece in this study was around 3.8 mW and yielded about 23 times more power than a single-layers PZT element. Their results shows the generation characteristics were improved by laminated PZT elements when the number of folds was increased.

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Roller chains are applied in two wheels, constructing machine and agricultural machine as the power-transmitting means. Compared with a belt as a winding transmission device, chain transmission is of advantage in transmission efficiency and capability. However, there is a problem of elongation caused by wear between pin and bush, which make flexion movement. Generally to decrease the wear, although a certain additive agent such as wear inhibitor is mixed with lubricant, the advantageous effect does not exist for very long time. Because the side surfaces of pin and bush are opened up to the air. Our past result presents that the contact between pin and bush occurs only at the both ends of the pin. On the basis of this resultant, the authors dealt with the possibility of decrease of wear by reducing contact surface pressure with enlarging the contact area between pin and bush. Then, crowning process to reduce edge load in cylindrical roller bearing was experimented. Furthermore, an optimized design, to enlarge the contact area by means of FEM analysis with considering the deformation of bush due to the press fitting, was also studied. Consequently, in this research, the decrease of wear depth by enlarging the contact area was verified by some experiments.

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We propose a mechanical combined-type continuously variable transmission (CVT) which has quadric-crank chains, one-way clutches, and plate-cams, as one of the conduction mechanisms. Since the proposed mechanical design is not based on friction conduction, it does not need any consideration about tribology phenomena between transmission components. Also, our design provides advantage for creating no slip, and it can maintain high transmission efficiency. Especially in this paper, we explain about design for a plate cam using an envelope curve, and we realize the CVT's fundamental function to sustain the relationship between the rotation in input and output axes. Concretely, we proposea combined-type CVT with quadric-crank chains, one-way clutches, spur gears and plate cams, and we analyze the curve of the cam for the CVT. Furthermore, we design the grooved cam based on the envelope curve theory in order to control the gear ratio smoothly.

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