Pump device

A system including a pump device (10) for operating a vacuum drainage systems and for pumping sewage, comprising

• a drive device (20) having a drive shaft (22) that comprises a first shaft end (22a) and a second shaft end (22b) and can be rotated by means of the drive device (20),
• a centrifugal pump (30) having at least one impeller (32) that is connected in a torque-proof manner to the drive shaft (22) in a region of the first shaft end (22a),
• a vacuum pump (40) having at least one rotor (42) that is connected in a torque-proof manner to the drive shaft (22) in a region of the second shaft end (22b),
• each of the centrifugal pump (30) and the vacuum pump (40) being connected to the drainage system,
• the vacuum pump (40) being provided with a first port on a suction side thereof and a second port on a pressure side thereof,
• the centrifugal pump (30) being provided with third and fourth ports,
• the first port of the vacuum pump (40) on the suction side thereof being connected indirectly to the drainage system via a buffer storage,
• the buffer storage (70) being kept under vacuum by the vacuum pump (40) and sewage can be pumped out of the buffer storage (70) by the centrifugal pump (30), and
• the third port of the centrifugal pump (30) being on a pressure side thereof and discharging the pumped sewage, the fourth port of the centrifugal pump (30) being on the suction side thereof and sucking sewage into the centrifugal pump (30),
• the centrifugal pump (30) being in direct connection to the drainage system by the fourth port on the suction side of centrifugal pump (30) and in fluid line connection to the buffer storage, the direct connection of the centrifugal pump to the drainage system below the first port of the suction side of the vacuum pump (40) allowing discharging sewage contained in the buffer storage, and
• a cutting device (50) having a rotatable cutting knife, wherein the rotatable cutting knife (52a) is connected in a torque-proof manner to the drive shaft (22) in the region of the first shaft end (22a) upstream of the impeller (32) and downstream of the buffer storage.