A bearing device includes a rotational shaft; a first outer ring; a second outer ring; first balls; second balls disposed; and a C-spacer and a second spacer. α>δd is satisfied, where δd represents a difference between an inside diameter of the second spacer at an end portion on a second side and an outside diameter of a shaft outer circumferential face, and α represents a half of a difference between a diameter of a cylindrical face of the C-spacer on an outer circumferential side and a diameter of the cylindrical face of the C-spacer on an inner circumferential side.

According to one embodiment, a sliding bearing unit includes a stationary shaft including a first radial bearing surface, a rotor, and a lubricant. The rotor includes a first cylinder and a second cylinder. The second cylinder includes a second radial bearing surface and is restricted in operation so that it does not rotate relative to the first cylinder. The lubricant, together with the first radial bearing surface and the second radial bearing surface, forms a dynamic pressure radial sliding bearing.

The disclosure relates to an X-ray tube, comprising a cathode and an anode, the cathode and anode being accommodated in a housing which provides a vacuum environment.

A bearing structure for an X-ray tube is provided that includes a journal bearing shaft with a radially protruding thrust bearing encased within a sleeve. The structure of sleeve is formed with enlarged traps or voids in the sleeve that are disposed adjacent various rotating anti-wetting seals/seal surfaces formed between the sleeve and the shaft. The geometry of the traps is formed to retain liquid metal/lubricating fluid within the gap defined by the bearing assembly and to direct to liquid metal flowing outwardly from the gap defined between the sleeve and the shaft away from the rotating anti-wetting seals and back towards the gap. This geometry allows the centrifugal forces exerted on the liquid metal by the rotation of the bearing structure to move the outflowing liquid metal away from the rotating anti-wetting seals to significantly reduce contact of the liquid metal with the seals.

The disclosure relates, inter alia, to a rotary anode bearing assembly for an X-ray tube comprising at least one bearing outer ring and rolling elements arranged within the at least one bearing outer ring, which rolling elements roll on the at least one bearing outer ring and enclose a radially inner receiving space for receiving a rotor of an X-ray tube; comprising a bearing housing in which the at least one bearing outer ring is mounted, wherein the bearing housing circumferentially surrounds the at least one bearing outer ring.

The rotary anode bearing assembly according to the disclosure is characterized in that an end face of at least one bearing outer ring or of a caulking ring axially adjoining the bearing outer ring is caulked to an end face of the bearing housing by plastic deformation of material of the bearing housing and/or of the bearing outer ring and/or of the caulking ring.

Systems and methods related to hydrodynamic bearings for use in X-ray sources are provided. In one aspect, a hydrodynamic bearing system includes a sleeve assembly including a cross-member fluidically dividing a first interior cavity from a second interior cavity, a first shaft positioned in the first interior cavity, and a second shaft positioned in the second interior cavity. The hydrodynamic bearing system may further include a first journal bearing including a first fluid interface surrounding at least a portion of the first cantilever shaft and configured to support radial loads and a second journal bearing including a second fluid interface surrounding at least a portion of the second cantilever shaft and configured to support radial loads.

A bearing structure for an X-ray tube is provided that includes a journal bearing shaft with a radially protruding thrust bearing encased within a bearing sleeve, one of which rotates relative to the other. The stationary component, e.g., the journal bearing and/or the thrust bearing includes at least one vent groove formed therein that improves the ability of the journal bearing structure to enable gases trapped by the liquid metal within the bearing assembly to escape through the vent groove to the exterior of the X-ray tube. By adding a strategically located channel or vent groove of sufficient size in at least one of the journal bearing or the thrust bearing, the pressures resisted by the seal created between the liquid metal and the vent groove(s) in the bearing components is significantly reduced, allowing escape of the gases to avoid detrimental effects to the operation of the X-ray tube, while maintaining the load carrying capacity of the bearing assembly.

In one embodiment, a rotating anode type X-ray tube comprises a fixed shaft having a first surface, a rotor, a cathode emitting electrons, and an anode target. The rotor comprises a first cylinder having a second surface, a second cylinder, and a third cylinder. A first threaded portion on an inner surface of the first cylinder and a second threaded portion on an outer peripheral surface of the third cylinder are tightened. A screw member is screwed in a third threaded portion on an inner peripheral surface of a hole which penetrates the third cylinder, and a tip portion of the screw member presses the second cylinder against the second surface.

A bearing structure for an X-ray tube is provided that includes a journal bearing shaft with a radially protruding thrust bearing encased within a sleeve. The structure of sleeve is formed with enlarged traps or voids in the sleeve that are disposed adjacent various rotating anti-wetting seals/seal surfaces formed between the sleeve and the shaft. The geometry of the traps is formed to retain liquid metal/lubricating fluid within the gap defined by the bearing assembly and to direct to liquid metal flowing outwardly from the gap defined between the sleeve and the shaft away from the rotating anti-wetting seals and back towards the gap. This geometry allows the centrifugal forces exerted on the liquid metal by the rotation of the bearing structure to move the outflowing liquid metal away from the rotating anti-wetting seals to significantly reduce contact of the liquid metal with the seals.

As gantry speeds experienced in CT scanners increase, so too does the radial load force exerted on components attached to the gantry. A self-lubricating sliding bearing used inside a rotary X-Ray source of a CT scanner is particularly susceptible to increasing radial load force, because in operation, a self-lubricating bearing floats on a film of liquid lubricant. Thus, the radial load force will tend to act on the floating portion of the bearing to develop an eccentricity in the longitudinal axis of the floating portion of the bearing as compared to the longitudinal axis of the stationary part of the bearing. The eccentricity will eventually cause the floating portion of the bearing to contact the stationary part of the bearing in operation, thus limiting the load carrying characteristic of the self-lubricating sliding bearing. Accordingly, the present application proposes a modification to the design of a self-lubricating sliding bearing, in which the pumping pattern of the bearing is reduced or removed at special portions within the bearing, to thus compensate for the effect of the radial load force.