The transverse section of piston skirt is not a standard circle and is with high precision. So the section curve should be interpolated through the high accuracy method of circular arc interpolation before NC machinin...The transverse section of piston skirt is not a standard circle and is with high precision. So the section curve should be interpolated through the high accuracy method of circular arc interpolation before NC machining. In order to smooth the connection of adjacent arcs and shorten the NC machining program, an interpolation method based on Chebyshev theory of function approximation is proposed here. According to the analysis of the interpolation error, the algorithm is simple and with high precision. By this way the fewest interpolating circular arc segments can be got, and the manufacture requirement is satisfied with the circular arc interpolating curves.展开更多
As an alternative power source for hybrid electrical vehicle(HEV), electric generating system(EGS) driven by sphere cam engine(SCE) is said to own higher power density and integration. In this work, the structure and ...As an alternative power source for hybrid electrical vehicle(HEV), electric generating system(EGS) driven by sphere cam engine(SCE) is said to own higher power density and integration. In this work, the structure and working principle of EGS were introduced, based on which the advantages of EGS were displayed. The profile of sphere cam was achieved after the desired motion of piston was given. After establishing the dynamic model of power transmission mechanism, the characteristics of cam-roller mechanism were studied. The results show that the optimal cam profile of SCE is a sinusoid curve which has two peaks and two valleys and a mean pressure angle of 47.19°. Because of the special cam shape, the trace of end surface center of piston is an eight-shape curve on a specific sphere surface. SCE running at speed of 3000 r/min can generate the power of 33.81 kW, which could satisfy the need of HEVs. However, the force between cylinder and piston skirt caused by Coriolis acceleration can reach up to 1182 N, which leads to serious wear between cylinder liner and piston skirt and may shorten the lifespan of SCE.展开更多
文摘The transverse section of piston skirt is not a standard circle and is with high precision. So the section curve should be interpolated through the high accuracy method of circular arc interpolation before NC machining. In order to smooth the connection of adjacent arcs and shorten the NC machining program, an interpolation method based on Chebyshev theory of function approximation is proposed here. According to the analysis of the interpolation error, the algorithm is simple and with high precision. By this way the fewest interpolating circular arc segments can be got, and the manufacture requirement is satisfied with the circular arc interpolating curves.
基金Projects(51475464,51175500,51575519)supported by the National Natural Science Foundation of China
文摘As an alternative power source for hybrid electrical vehicle(HEV), electric generating system(EGS) driven by sphere cam engine(SCE) is said to own higher power density and integration. In this work, the structure and working principle of EGS were introduced, based on which the advantages of EGS were displayed. The profile of sphere cam was achieved after the desired motion of piston was given. After establishing the dynamic model of power transmission mechanism, the characteristics of cam-roller mechanism were studied. The results show that the optimal cam profile of SCE is a sinusoid curve which has two peaks and two valleys and a mean pressure angle of 47.19°. Because of the special cam shape, the trace of end surface center of piston is an eight-shape curve on a specific sphere surface. SCE running at speed of 3000 r/min can generate the power of 33.81 kW, which could satisfy the need of HEVs. However, the force between cylinder and piston skirt caused by Coriolis acceleration can reach up to 1182 N, which leads to serious wear between cylinder liner and piston skirt and may shorten the lifespan of SCE.
