Pump Assembly

A centrifugal pump assembly, comprising:

• a hydraulic casing;
• a suction port, which is formed on the hydraulic casing and has an inlet opening;
• a pressure port, which is formed on the hydraulic casing and has an outlet opening;
• a flow chamber, which is at least partially delimited by the hydraulic casing;
• a casing cover, which closes the hydraulic casing;
• an impeller, which is arranged in the flow chamber and is drivable about an axis of rotation via a shaft;
• and
• an inflow nozzle having a first end, which is connected indirectly or directly to the hydraulic casing, and a substantially cylindrical portion, which extends coaxially with the axis of rotation toward the inlet opening, wherein
• a second, free end opposite the first end is arranged in a recess of the inlet opening at the transition from the inlet opening to the flow chamber,
• a radial annular gap is produced between the portion of the inflow nozzle and the hydraulic casing in a region of the recess,
• the portion is divided into a first sub-portion and a second sub-portion, which is close to the free end, and the second sub-portion comprises a sleeve-like or ring-like expansion element in the region of the free end, and
• a material of the expansion element has a higher coefficient of thermal expansion than a material of the hydraulic casing.