Gear ratio and shift schedule optimization of wheel loader transmission for performance and energy efficiency

• Simplified automated manual transmission (AMT) and dual clutch transmission (DCT) simulation models are developed.
• Gear ratio and shift schedule optimization strategies are proposed based on standard V-pattern working data.
• Feasibility study is conducted by analyzing working performance and energy consumption.
• Clutch-type transmission based wheel loader is more energy efficient than torque converter based wheel loader.

This paper presents gear ratio and shift schedule optimization strategies to improve energy efficiency for the dynamic simulation of a wheel loader equipped with dual clutch transmission (DCT) and automated manual transmission (AMT). A conventional wheel loader uses torque converter (T/C) based automotive transmission, and the torque converter causes heavy energy loss during the V-pattern working cycle. To improve fuel economy while maintaining working performance in the V-pattern working cycle, automated manual transmission (AMT) and dual clutch transmission (DCT) have been suggested to substitute the clutch for the torque converter. In addition, the optimization strategies for the gear ratio and shift schedule for AMT and DCT have been proposed for improving fuel economy. Gear ratios have been determined by a nonlinear optimization method based on the standard V-pattern working cycle which is obtained from experimental test data by a skilled driver. Then, the gear-shift schedule for clutch-type transmission has been derived by using a determined gear ratio and optimization strategy. Simulations have been conducted to investigate working performance and energy efficiency by using three developed wheel loader simulation models equipped with T/C, AMT, and DCT, respectively, with the driver model for the V-pattern working cycle. Simulation results show that AMT- and DCT-based wheel loaders are more fuel efficient for the V-pattern working cycle than the T/C-based wheel loader.