Effects of piston tapered angle on the output characteristics for large displacement bent–axis piston motor

Large displacement bent–axis piston motors are widely utilized as actuators in construction machinery. Piston structural parameters have a direct effect on the motor output characteristics. In this paper, the effects of the piston tapered angle on the motor output characteristics were investigated. A motor model considering the piston tapered angle and the rotation angle difference was established. Kinematics of the tapered piston and the cylinder block, and output torque of the motor were analyzed. Numerical simulations and experimental investigations were conducted. Relationships between the piston tapered angle and the other motor structural parameters were analyzed. The pitch radius ratio based on the structural parameters was used to evaluate the motor output characteristics. Results show that a larger piston tapered angle results in a greater rotation angle difference, thereby causing a larger increase in speed fluctuation. A slight 1° increase in the piston tapered angle causes a significant 20.11% increase in speed fluctuation at 500 rpm and 20 MPa. When the pitch-radius ratio is satisfied, speed fluctuations decrease from 3.49% to 0.86%.