Thermally isolated x-ray tube bearing

An x-ray tube comprising:

• an envelope which defines an evacuated chamber;
• a cathode disposed within the chamber which provides a source of electrons;
• an anode disposed within the chamber which is struck by the electrons and generates x-rays;
• a bearing shaft, connected with the anode, the bearing shaft including:
• an inner portion,
• a peripheral portion connected with the inner portion, the peripheral portion having a forward bearing race and a rear bearing race on an exterior surface thereof, the forward bearing race being closer to the anode than the rear bearing race, the inner portion and the peripheral portion defining an annular gap at least partially therebetween which extends longitudinally into the bearing shaft and spaces a forward end of the inner portion from a forward end of the peripheral portion, and
• at least one contact element positioned within the gap between the forward end and the rear end to maintain separation and limit vibration, the contact element being longitudinally positioned between the forward bearing race and the rearward bearing race;
• and
• lubricated bearings received by the forward bearing race and rear bearing race.

An x-ray tube comprising:

• an envelope which defines an evacuated chamber;
• a cathode disposed within the chamber which provides a source of electrons;
• an anode disposed within the chamber which is struck by the electrons and generates x-rays;
• a rotor for rotating the anode relative to the cathode, the rotor including:
• a bearing shaft, connected with the anode, the bearing shaft including:
• an inner portion,
• a peripheral portion connected with the inner portion, the peripheral portion and the inner portion being separate components which are connected adjacent a rear end thereof, the peripheral portion defining a forward bearing race and a rear bearing race in an exterior surface thereof, the forward bearing race being closer to the anode than the rear bearing race, and
• the inner portion and the peripheral portion defining an annular gap at least partially therebetween which extends longitudinally into the bearing shaft and spaces a forward end of the inner portion from a forward end of the peripheral portion;
• at least one contact element positioned within the gap between the forward end and the rear end, the contact element having a roughened contact surface which reduces heat flow from the inner portion to the peripheral portion through the contact element;
• and
• lubricated bearings received by the forward bearing race and rear bearing race.

An x-ray tube comprising:

• an envelope which defines an evacuated chamber;
• a cathode disposed within the chamber which provides a source of electrons;
• an anode disposed within the chamber which is struck by the electrons and generates x-rays;
• a rotor for rotating the anode relative to the cathode, the rotor including:
• a neck connected with the anode;
• a bearing shaft including:
• an inner portion,
• a peripheral portion connected with the inner portion, the peripheral portion having a forward bearing race and a rear bearing race in an exterior surface thereof, the forward bearing race being closer to the anode than the rear bearing race, and
• the inner portion and the peripheral portion having an annular gap at least partially therebetween which extends longitudinally into the bearing shaft and spaces a forward end of the inner portion from a forward end of the peripheral portion;
• and
• a hub which extends from the forward end of the inner portion of the bearing shaft and is connected with a flange on the neck;
• and
• lubricated bearings received by the forward bearing race and rear bearing race.

A bearing member for an x-ray tube, the bearing member comprising:

• a bearing shaft including:
• an inner cylindrical portion;
• a peripheral portion, connected with the inner portion, the peripheral portion defining a first annular bearing race and a second annular bearing race in an outer surface thereof, the race being shaped to receive lubricated bearing members therein;
• an annular gap which extends into the bearing shaft generally parallel with the peripheral surface, and provides a thermal barrier between a portion of the peripheral portion adjacent the first bearing race and an adjacent portion of the inner portion;
• a spacer within the gap at a location between the first and second bearing races, the spacer having reduced thermal conductivity relative to the inner cylindrical portion;
• and
• a connecting member which extends from the inner portion, for connection with an anode.

A method of reducing evaporation of a bearing lubricant in an x-ray tube having an anode and a rotatable bearing shaft connected therewith, the shaft defining forward and rear bearing races on an exterior surface thereof, the method comprising:

• forming the bearing shaft with an annular gap defined in the bearing shaft between an inner component and a peripheral component defining the exterior surface;
• positioning a spacer in the gap between the inner component and the peripheral component, the spacer being positioned rearward of the forward bearing race;
• and
• channeling heat entering the bearing shaft from the anode past the forward bearing race along the inner component, a fraction of the heat flowing through the spacer and the peripheral component to the forward bearing race.