| 摘要 |
In a radial-piston machine, in particular a spherical-piston pump, an outer stator and an inner rotor are provided which is rotatable on a control journal provided with inflow and outflow ducts. The rotor has at least one radial bore in which a spherical piston, consisting of an outer sphere and an inner cylindrical sleeve can be displaced. The radially inner end of the sleeve can be connected to the high-pressure side of the machine. The radially outer end of the sleeve has an elastic sealing lip in the circumferential direction which in each operating state is in sealing contact with the rotor bore in which sleeve, sealing lip and sphere are accommodated. The sleeve accommodates the sphere in the manner of a socket and is designed to be axially symmetric with a central passage. The external diameter of the sleeve may correspond to that of the sphere. In operation, the operating pressure of the machine and, at higher rotor speeds, the centrifugal force, forces the sealing lip against the outer sphere and thus spreads it apart, resulting in an increase in the sealing force between lip and rotor bore. The invention is particularly suitable for high-pressure pumps and facilitates manufacture of the cylindrical sleeve, as the cylindrical outer shell of the sleeve can be manufactured with wide tolerances without significantly impairing the sealing effect overall. If the material of the sleeve is chosen appropriately (large thermal coefficient of expansion compared to the rotor), elevated operating temperatures can be utilised in order to provide good areal sealing between the cylindrical outer shell of the sleeve and the enclosing rotor bore.
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