INFLUENCE OF THE VALUE OF THE DIAMETER GAP ON THE KINEMATICS OF MOVEMENT OF THE INNER ROTOR OF THE ORBITAL HYDROMOTOR

Abstract

Orbital hydraulic motors are widely used in the gearless hydraulic drive of mechatronic systems of active working parts of self-propelled vehicles. A distinctive feature of the orbital hydraulic motor is its outer and inner rotor with a hypocycloidal tooth profile, between the centers of which there is no “rigid” kinematic connection. Such an arrangement of the rotors of the orbital hydraulic motor leads to non-standard changes in its characteristics during operation, which in turn limits the stability of the output characteristics of the hydraulic drives of self-propelled vehicles. By studying the kinematics of movement of the inner rotor of an orbital hydraulic motor, it has been established that the rotor can occupy two positions: when the value of the diametral clearance is less than the critical value (“self-sealing”) of the rotors and when the value of the diametral clearance is greater than the critical value (“depressurization”). With a change in the gap between the rotors in the range of 0 ... 0.4 mm, the overall efficiency of the volumetric hydraulic machine decreases by 3.6 times, which is explained by increasing leakage between its rotors. The high value (0.92) and the constancy of the volumetric efficiency of the orbital hydraulic motor is explained by the property of its rotors to “seal itself” in the process of moving, eliminating leakage. When the gap between the rotors changes in the range of 0.4…0.8 mm, the angular velocity decreases from 34 to 27 rad/s, caused by additional movements of the inner rotor in the area under consideration. The decrease in volumetric efficiency by 18%, overall efficiency by 35% and the increase in leakage flow from 0 to 17 l/min is due to the presence of leakage flow between the high and low pressure chambers.