New generation of the satellite hydraulic pumps

Hydraulic satellite machines are known and produced in many versions, recognizable by the number of humps on their inner rotor and external gear, and therefore by the number of cooperating gears (satellites). All known shapes were however designed on the base of preliminary assumption that rotor’s and external gear’s pitch lines are formed by merging arcs, tangent to each other in the. This assumption makes calculations easier, but the curvature radius of the pitch lines changes instantly in their merging points. Tests made in the Department of Hydraulics and Pneumatics of the Gdańsk University of Technology proved that satellite motors may work also as a pump. All known shapes were however designed for motor work - mainly for low-speed, high-torque motors. Sudden changes of the pitch line’s curvature strongly affect velocity and acceleration of pump’s moving parts and forces between them. Because of that, in the pump mode fast wear of teeth in the points of small curvature radius is visible. The obvious effect is reduced durability and high noise emission. To eliminate all those problems the new mechanism, designed for the pump is necessary. The author worked out the new method of calculating satellite mechanism’s shape. Instead of merged arcs this method allows to form pitch line as a smooth shape with constantly variable curvature (no rapid changes in any point). Such a mechanism with two-humped rotor, four-humped external gear and six satellites was designed with the use of the new method. Curvature radii of all cooperating elements are relatively high. The proposed shape reduces rapid changes of velocity and forces between pump’s elements. It should result in more durable hydraulic satellite pump.