Adaptive shift strategy of a novel power-cycling variable transmission for construction vehicles

A new power-cycling variable transmission (PCVT) is proposed and applied to construction vehicles to improve transmission efficiency. To adapt to changes in external loads, construction vehicles need to shift gears continuously. However, the shift points obtained by traditional method cannot change with working conditions. This study aims to identify construction vehicles' mass and gradient changes, and to develop a shift correction strategy. The double-forgetting factors least squares method is designed to identify slope gradient and load. A PCVT dynamic shift strategy is developed based on speed ratio adjustment characteristics. Next, a modified shift strategy under different loading mass and slope gradient conditions is proposed based on the construction vehicles' mass change ratio, the gradient change ratio and balanced velocity. Simulation results show the proposed method can correct shift points, improve operation efficiency, avoid shift cycles and ensure a safer operation process.