Vane pump

A vane pump used for dividing into portions a pasty and compressible substance, comprising a pump housing (1) with a wall (4), a base (5), and a cover (6), said vane pump further comprising, a rotor (2) which is arranged eccentrically in said pump housing and which is adapted be to rotated, and vanes (3) which are supported within said rotor (2) such that they are radially displaceable, said vanes (3), said wall (4) of the pump housing (1), said base (5) a cover (6) of said housing (1), and an outer surface (7) of the rotor (2) defining vane cells (8) and said vanes (3) in sealing engagement with said wall (4), said base (5), said cover (6), and said outer surface (7) of said rotor (2), said pump housing (1) further having a substance inlet (9) and a substance outlet (10) which have arranged between them a compression sector (11) and a dosing sector (12), and a pressure-relief valve (13, 14) being arranged at least in the area of the dosing sector, and including a back-flow passage (32) arranged in such a way that, when the pressure-relief valve (13, 14) responds, said valve (13, 14) will connect the interior of the pump housing (1) via the back-flow passage (32) to the inlet (9).