DYNAMIC MODEL OF A HYDRAULIC DRIVE OF A MECHATRONIC SYSTEM WITH A PLANETARY HYDRAULIC MOTOR

This paper summarizes computational studies of the dynamic characteristics of a mechatronic hydraulic drive with standard and modernized planetary hydraulic motors. The aim is to compare the effects of motor design, external disturbances and passive pulsation damping on the transient response of the drive. The analysis considers the flow area of the distribution system, the diametral clearance between the rotors, pump delivery variations and changes in resisting torque. Three cases are examined: constant pump delivery and resisting torque, variable external inputs, and operation with a passive pulsation damper. Variations in the distribution flow area are associated with pressure and flow rate pulsations, while variations in the diametral clearance are associated with torque oscillations. Under variable external inputs, the modernized motor exhibits smaller pressure and torque oscillations and reaches the operating speed level earlier than the standard motor. In the case with a passive pulsation damper of 5000 cm³, the approximate start-up pressure peaks are 38 and 36 MPa for the standard and modernized motors, respectively, compared with 90 and 85 MPa without the damper. The start-up torque peaks are within 900–1000 N·m for both designs, compared with approximately 2100 and 1900 N·m without the damper. However, oscillations under variable loading remain in both designs. The results support considering motor design improvements and passive damping together when selecting measures to reduce pulsations and start-up loads. The numerical estimates apply to the cases considered, taking into account differences in their initial parameters and operating conditions.