Dosing valve

A dosing valve, comprising a valve body having an inlet opening and an outlet opening which extend from a common overflow chamber, a diaphragm which, together with the valve body, delimits the overflow chamber and is movable between an open and a closed position, wherein, in the closed position, the diaphragm rests on at least one valve seat in the overflow chamber and prevents flow from the inlet opening to the outlet opening, wherein a drive for the diaphragm is connected thereto at the rear at a coupling area via an actuating lever, and the actuating lever pivots between the open and the closed position about a pivot axis, moves the coupling area along an arc, and tilts the diaphragm, wherein the diaphragm includes an edge having a circumferential bead which projects towards the valve body and delimits the overflow chamber laterally, and the edge is clamped axially between the valve body and a retaining part, wherein the retaining part extends at the rear beyond the edge inwardly towards the coupling area and forms a supporting surface for the diaphragm in the open position, which runs rotationally asymmetrically around the coupling area, and an area of the supporting surface closest to the pivot axis runs obliquely inwards towards the coupling area to a plane defined by the valve seat, and the area of the supporting surface furthest away from the pivot axis maintains a greater distance from the plane towards the coupling area, and wherein the supporting surface is designed and positioned such that the diaphragm rests thereon along a closed circumferential ring surface in the open position when the dosing valve is unpressurized.