Research on the Output Characteristic of a New Water Hydraulic Electrohydraulic Motor

For the hydraulic drilling tool under deep water, an integrated structure of a water hydraulic electrohydraulic motor is proposed, which consists of three parts: pump unit, motor unit, and DC brushless motor. The two-dimensional piston in the pump unit has two degrees of freedom of motion: rotation and reciprocation, so it is compact and can be matched with a high-speed motor to become a high-speed motor pump; the two sets of plungers in the motor unit are balanced with two end-facing cam drive mechanisms to achieve axial force, which is also suitable for high-speed rotation. In this paper, the mechanical structure and working principle of the electrohydraulic motor are described, the mathematical model of the output characteristics of the electrohydraulic motor is established, and the joint simulation model of Adams and AMESim is built, then the relationship between the dynamic characteristics of the electrohydraulic motor and the structure and working parameters is studied. The results show that the higher the speed of the pump unit, the smoother the characteristics of the electrohydraulic motor, when the motor speed is increased from 1000 r/min to 3000 r/min, the pulsation amplitude of the electrohydraulic motor speed is decreased by 200%; the plunger sub of the motor unit should take proper clearance, if the plunger sub clearance is increased to $12~\mu \text{m}$ , the output speed is decreased by 40% and the leakage volume is increased by 25 times; the motor unit should have proper back pressure to facilitate the smoothness and life of the motor, when the back pressure value is increased from 0.2 MPa to 1.2 MPa, the pressure pulsation at the beginning of the start-up is also greatly reduced.