Patent ID: 8282366

Claim:
A pump comprising a stator, a rotor comprising an axial extension slidably and rotatably mounted at least partially in a rotor chamber of the stator, and at least a first valve between an inlet and the rotor chamber, and at least a second valve between the rotor chamber and an outlet, wherein both the first valve and the second valve open and close as a function of at least an angular displacement of the rotor, the pump further comprising interacting rotor cam element and stator cam element on the rotor and stator respectively, and biasing means acting on the rotor for applying a force on the rotor in an axial direction of the stator cam element, said rotor cam element and stator cam element being configured such that they are separated by a certain axial distance h at a specified angular position of the rotor in respect to the stator when both valves are closed and at said specified angular position said rotor cam element is not in contact with said stator cam element.