TECHNICAL FIELD

The present invention relates to a geared volumetric machine. It is typically a pump but could also be a motor.

PRIOR ART

Geared pumps are known comprising cogged wheels with helical teeth. Two types of axial forces are generated on helical teeth: a mechanical one due to the interaction between the teeth and a hydrostatic one generated by the pressure acting in the compartments between the teeth. The axial force on the drive wheel is given by the sum of these two components, while on the driven wheel such two components are subtracted. Such axial force, considering the prolonged and pulsating stress, can reduce the efficiency, determine reliability problems or however generate premature wear on one of the two shims placed to the side of the cogged wheels, in particular at the cogged drive wheel. In order to completely or partially contrast such thrust (and reduce wear) a piston is known which exerts a balancing force on the cogged wheel, acting in a second direction opposite to the first.

In an alternative solution, there is a groove having a width of 2 millimetres on the shims and which extends according to an arc of a circle remaining at a constant distance from a rotation axis of one of the cogged wheels.

A fluid at high pressure is conveyed inside such groove, which exerts a counter-force in part the axial thrust induced by the helical teeth.

OBJECT OF THE INVENTION

The object of the present invention is to provide a volumetric machine that allows the manufacturing costs to be reduced, optimising the components. A further object of the present invention is that of minimising wear and therefore maximising the efficiency and reliability of a volumetric machine.

The stated technical task and specified objects are substantially achieved by a volumetric machine comprising the technical features disclosed in one or more of the appended claims.

