Series pump-step arrangement with controllable useful delivery rate for mobile use

摘要

Pressure-medium supply device for different-pressure supply circuits and varying supply-quantity requirements at varying pump drive speeds for mobile use, in particular for supplying pressure oil to CVTs and automatic change gears. It consists of a plurality of pump steps which can be connected by means of appropriate hydraulic switching elements both in parallel and in series and can be mechanically interconnected via a variable-ratio or differential gear and are in torque or power equilibrium with respect to one another. One constructional feature consists in designing the variable-ratio or differential gear as a pump itself. By means of the mechanical connection according to the invention, via a variable-ratio or differential gear, of hydraulic series-connected pump steps, the speeds and thus delivery rates of the individual pump steps can be varied with respect to one another, and partial streams for lower-pressure supply circuits can be drawn off, the distributed pressure application and thus uniform loading of the individual pump steps being maintained in a predetermined manner. As a result of this variation and optimisation possibility and joint supply of further hydraulic circuits, efficient driving-power minimisation and an overall pressure-medium supply concept favourable in terms of cost and structural expense is made possible.