Rotating union for two different fluids

In a rotating union for first and second different fluids, which rotary union includes a stationary housing having a hollow shaft mounted rotatably therein and comprising a central throughflow channel therein for the first fluid and at least one second throughflow channel parallel thereto for the second fluid, two separate inlet channels in the housing being provided for the first and second fluids and a slide ring packing assembly provided between the inlet channels and the hollow shaft and arranged coaxially with an axis of rotation of the hollow shaft and through which the first and second fluids are supplied separately to the throughflow channels, the slide ring packing assembly including a common slide ring for conducting the first and second fluids which is connected at an interface with the inner end of the hollow shaft and comprises a central bore and several axial passages arranged in a circle concentric to the axis of rotation, and a central slide ring in the housing, as well as a concentric slide ring concentrically surrounding the central slide ring, each being held non-relatively rotatably in concentric piston-like slide ring supports and axially displaceable in associated cylinder chambers in the housing, and the respective opposing sliding surfaces are biased axially together independently of each other under spring pressure and the pressure of the respective fluid, the improvement wherein the concentric slide ring comprises several axial passages which are arranged in a circle concentric to the axis of rotation and connected to an inlet channel for the second fluid via a cylinder chamber for an outer one of the slide ring supports carrying the concentric slide ring, wherein at least one of the common slide ring and the concentric slide ring in the region of the axial passages in the respective sliding surface is provided with an annular groove connecting the axial passages to each other, wherein between the outer circumference of the central slide ring and the inner circumference of the concentric slide ring there is provided an annular chamber extending as far as the sliding surface on the common slide ring, wherein the housing further includes a third cylinder chamber in which is reciprocally slidably mounted an annular piston, wherein the annular chamber communicates with the third cylinder chamber, and wherein in the housing are provided a third inlet channel and an outlet channel which communicate with the third cylinder chamber.