| 摘要 |
A piston diaphragm pump for delivering doses of liquids, in particular surfactants, wetting agents or the like, has a pump piston movably guided in a pump tube that encloses the pump pressure chamber, and can be electromagnetically driven against the force of a return spring by a magnetic coil that surrounds the pump tube. In addition, a pump diaphragm that is peripherically clamped to the pump housing and faces on one side the pump suction chamber, is rigidly connected on the suction side to the pump piston. A longitudinal bore, within which is arranged a pump piston provided with a piston valve, extends centrally through the pump diaphragm and links the pressure chamber to the suction chamber. In order to obtain the same pump capacity with reduced pump lifts, without the need for providing a specially sealed guidance of the pump piston in the pump tube, the working chamber locted on the side of the pump diaphragm opposite to the suction chamber is designed as an additional pump pressure chamber that is constantly connected to the piston longitudinal bore that leads to the pump tube pressure chamber by cross-channels arranged in the pump piston behind the piston valve.
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