Internal bearing cooling using forced air

A method of reducing bearing temperature in an x-ray tube to increase bearing life, the method comprising the steps of:

• connecting a hollow bearing passage with a source of cooling fluid;
• after connecting the hollow bearing passage with the source of cooling fluid, connecting an interior of the x-ray tube with a vacuum source to evacuate the interior of gases;
• after connecting the interior of the x-ray tube with a vacuum source, placing the x-ray tube in a baking oven and baking the tube at a preselected temperature to outgas components in the interior;
• and
• passing the cooling fluid through the hollow bearing passage to maintain an associated bearing assembly below a predetermined temperature.

A manufacturing assembly for an x-ray tube comprising:

• a baking oven;
• an envelope disposed within the baking oven, the envelope defining a chamber which houses a cathode for providing a source of electrons and an anode positioned to be struck by the electrons and generate x-rays;
• a rotor operatively connected to the anode for rotating the anode relative to the cathode, the rotor having a bearing assembly which has a hollow bearing shaft;
• a vacuum pump coupled to a tubular portion of the envelope for removing unwanted molecules and gases from the chamber;
• and
• a supply pump for supplying a cooling medium through the hollow bearing shaft so that bearing components of the bearing assembly can be cooled.

An x-ray tube assembly comprising:

• an envelope defining an evacuated chamber, said envelope housing a cathode for providing a source of electrons and an anode positioned to be struck by the electrons and generate x-rays;
• a rotor operatively connected to the anode for rotating the anode relative to the cathode, the rotor including.
• a bearing assembly including a central tubular shaft surrounded by a hollow bearing shaft, and bearings disposed in the evacuated chamber between the bearing shaft and a cylindrical sleeve on which the anode is supported, the bearings having a coating, the coating tending to evaporate into the evacuated chamber when heated;
• and
• a first air supply connected to the tubular shaft which takes and directs cool air from the first air supply into and through the hollow bearing shaft such that the bearings of the bearing assembly are cooled by the cool air flowing thereover, reducing the tendency of the coating to evaporate into the evacuated chamber.

A method for manufacturing an x-ray tube, the x-ray tube having an anode rotatably connected to a rotor, the rotor having a hollow bearing shaft for receiving cooling oil, air, or gas during operation, and bearings between the rotor and the bearing shaft, the method comprising:

• baking the x-ray tube at a baking temperature;
• vacuum pumping gases and molecules from an interior chamber of the x-ray tube;
• and
• concurrently with the baking, forcing a cooling medium through the hollow bearing shaft to maintain the bearings below the baking temperature.