Embodiments of the present invention relate generally to a rotating union for transferring fluids from a stationary supply to a rotating component. More particularly, the embodiments of the present invention relate to a rotating union for preventing leakage of fluid between a rotating component and a stationary supply in an X-ray tube based imaging system.
X-ray tube based imaging systems, such as computed tomography (CT) imaging systems as well as non-destructive testing systems, employ X-ray sources located on a gantry. Typically these x-ray tubes are anode based x-ray tubes. These anode X-ray tubes typically require high voltage to generate X-rays. Unfortunately these anode X-ray tubes tend to get heated while generating the X-rays. Currently, X-ray tubes employing a rotating shaft protruding out of a vacuum vessel may use a Ferro-fluidic seal to separate vacuum from the atmosphere. The liquid coolant may be directed through the rotating shaft to cool the X-ray target, the Ferro-fluidic seal and the shaft bearings. This configuration needs supply of coolant from a non-rotating part to the rotating part without leakage.
Furthermore, in CT systems, the gantry is rotated around an object at very high speeds. The high speed rotation of the gantry creates a centrifugal force which may typically be in multiples of the force of gravity thereby creating high gravitational loads (G-loads) on a rotating object. A standard face seal rotating union can fail to prevent leakage caused due to high G-loads. The high G-loads may cause the rotating shaft coupled to the X-ray target to bend thereby causing the rotating face seal to misalign from the non-rotating face seal mate. This may cause uneven wear resulting in leakage of coolant. Additionally, a gap may be formed between the faces of the seals causing leakage of coolant. Also, the liquid coolant for cooling various components of the X-ray tube may leak from the rotating union due to the design of the rotating union especially for rotating unions employing standard face seals. Coolant leakage may also occur due to wear and tear of certain components or due to any malfunctioning of the rotating union. The coolant leakage may be detrimental to the imaging system which includes the rotating union or to the environment in which the imaging system operates. Furthermore, deflection of the shaft at the interface of a mechanical face seal may create pressure gradients that may in turn cause uneven wear, leakage and shorter life of a mechanical face seal.
It is therefore desirable to prevent fluid leakage from a rotating union without employing a mechanical face seal.