Powder rotary feedthrough having a purge chamber

A rotary feedthrough for the feedthrough of a non-lubricating powder-gas mixture from a stationary machine part into a rotating machine part, comprising:

• a housing;
• a stationary powder transport channel;
• a rotating powder transport channel;
• a purge chamber comprising at least one opening for the stationary powder transport channel and at least one opening for the rotating powder transport channel, in which the at least one opening for the stationary powder transport channel and the at least one opening for the rotating powder transport channel are concentrically arranged with an axis of rotation of the rotating machine part;
• a seal arranged within the purge chamber between facing ends of the stationary powder transport channel and of the rotating powder transport channel, the seal comprising two flat circular-ring-shaped sliding seal surfaces arranged one on the other in a sliding manner, each of the sliding seal surfaces being arranged concentric to the axis of rotation of the rotating machine part and being movable relative to each other in an axial direction along the axis of rotation of the rotating machine part;
• the purge chamber further comprising at least one gas inlet and at least one gas outlet, in which the at least one gas inlet and the at least one gas outlet are arranged on diametrically opposing sides of the purge chamber and are aligned transversely to the axis of rotation of the rotating machine part, and the purge chamber also comprising a purging channel connecting the at least one gas inlet and the at least one gas outlet, wherein a purging gas is suppliable from the at least one gas inlet to the at least one gas outlet through the purging channel;
• and
• bearings arranged in the housing to allow for rotational and axial movement of the rotating powder transport channel within the purge chamber,
• wherein the two flat circular-shaped sliding seal surfaces, which include a rotating seal surface that is axially movable within the purging chamber and relative to a stationary seal surface, the rotating seal surface and the stationary seal surface being arranged within the purging channel and within a flow path of the purge gas suppliable through the purging channel from the at least one gas inlet and the at least one gas outlet,
• wherein the two flat circular-shaped sliding seal surfaces are in contact with each other with a resilient pretensionable force pressing the axially movable rotating seal surface along the axis of rotation toward the stationary seal surface.