Abstract: A fluid dynamic bearing motor including a stationary sleeve, a rotating shaft axially disposed through the sleeve, a journal gap between the shaft and the sleeve, the gap defined by first and second interfacial surfaces of the shaft and sleeve, at least one set of fluid dynamic grooves formed on the first interfacial surface of the journal gap, and at least one step defined on the second interfacial surface of the journal gap.

Abstract: A method of designing an improved bearing system is provided. In one embodiment, the method for designing a fluid dynamic bearing system includes determining a first stability ratio for a first journal bearing configuration. The method further includes determining a second stability ratio for a second journal bearing configuration. In one embodiment, the first configuration has two sub-journal bearings and the second configuration has three sub-journal bearings. The two stability ratios may then be compared to determine whether adding a sub-journal increases the stability ratio of the bearing system.

Abstract: A fluid dynamic bearing motor including a stationary sleeve, a rotating shaft axially disposed through the sleeve, a journal gap between the shaft and the sleeve, the gap defined by first and second interfacial surfaces of the shaft and sleeve, at least one set of fluid dynamic grooves formed on the first interfacial surface of the journal gap, and at least one step defined on the second interfacial surface of the journal gap.

Abstract: According to various embodiments of the invention, a motor with a rotatable hub having fluid dynamic journal and thrust bearings can be assembled from four major components: a spindle, a hub, a thrust washer, and a base. The spindle can integrate journal bearing, axial limiter, and ring seal functions. The hub can integrate journal bearing, thrust bearing, ring seal, axial limiter, capillary seal, and bumper functions. The thrust washer can integrate thrust bearing and lubricant circulation functions. The base can integrate capillary seal and lubricant storage and circulation functions. Each function can be integrated as structural feature in its corresponding component. The spindle, hub, and thrust bearing can be preassembled. The base can be loaded with lubricant prior to assembly with the spindle/hub/thrust bearing combination.

Abstract: An improved rotational motor, such as a spindle motor for a disc drive, is provided. The motor first comprises a hub having a shaft portion and a horizontal body portion. The motor also comprises a sleeve surrounding the shaft portion of the hub. A fine first vertical gap is retained between the shaft and the inner diameter of the surrounding sleeve. In addition, a fine horizontal gap is provided between the upper hub portion and the top of the sleeve. A third gap is preferably provided between the hub and an outer diameter of the sleeve. The first vertical gap is filled with a lubricating liquid, such as a clean oil. A capillary seal is provided in the third gap. In one embodiment, the lubricating liquid extends into the horizontal gap. Oil pumping grooves are machined along the horizontal fluid gap. When the hub is rotated, the oil pumping grooves impel oil towards the shaft. This prevents any portion of the first vertical gap from becoming un-lubricated during rotation of the shaft.

Abstract: A fluid bearing design is provided which according to one aspect includes a shaft defining together with a surrounding sleeve an asymmetric journal bearing, and a thrust bearing at or near an end of the shaft towards which the asymmetric journal bearing is pumping, with that end of the shaft being closed off. The journal bearing asymmetry establishes a hydraulic pressure toward the closed end of the shaft. This pressure provides an axial thrust to set the bearing gap for the conical bearing. The conical bearing itself is a relatively balanced bearing, although it may have a bias pumping toward the shaft and the journal bearing. A pressure closed equalization path from the journal bearing through the conical bearing to the end of the shaft may be established to maintain a constant hydraulic force across the conical bearing, and which may also prevent any asymmetry in the conical bearing from affecting the net thrust force acting upon the end of the shaft where the conical bearing is located.

Abstract: Hard disk drive track density is increased by selectively increasing the stiffness of a fluid dynamic bearing (FDB) motor during servo write. Applying a load to the shaft of a fixed shaft FDB motor to close the bearing gaps increases stiffness. Alternatively, the disk drive is cooled to increase bearing fluid viscosity or the motor is operated at an increased rotational velocity.

Abstract: A variable-gap fluid dynamic bearing motor assembly is described. In one embodiment, the assembly includes a hub configured to rotate about a rotational axis and to support at least one disc. The assembly also includes a first member attached to the hub and configured to rotate about the rotational axis and a second member. A first fluid dynamic journal bearing having a first bearing gap and a second fluid dynamic journal bearing having a second bearing gap are disposed between the first member and the second member. The bearing gaps are configured such that the second bearing gap is larger than the first bearing gap. Bearing fluid disposed within the first fluid dynamic journal bearing and the second fluid dynamic journal bearing to support the relative rotation of the first member and the second member.

Abstract: A disc drive design comprising a shaft and sleeve supported for relative rotation by a journal type fluid dynamic bearing utilizing grooves on one of the shaft or sleeve surfaces. At least a part of the shaft is generally conical in cross-section, so that a downward force component is developed to balance upward pressure on end of shaft; this conical region typically includes a fluid dynamic bearing (grooves being on either the shaft or sleeve). A grooved pattern of a design similar to that usually found on a thrust plate may be defined on an axial end surface of the shaft or the counterplate facing the axial end of the shaft, so that thrust is created to maintain separation of the end of the shaft and the facing counterplate plate during relative rotation. A diamond-like coating (DLC) may be applied to the counterplate surface or to the end of the shaft; further, either the counterplate or shaft may be made out of ceramic material to enhance this performance.

Abstract: The shaft may be supported for rotation by a conical bearing rotating within a sleeve. To prevent misalignment of the rotor and stator as the motor heats up and fluid viscosity changes, a magnetic preload is established; in a preferred embodiment, the magnetic preload is achieved using a magnetic back iron aligned with the stator magnet, the magnetic back iron being supported from the base. The shaft may further include a lower journal bearing for maintaining radial alignment and/or stiffness. A shaft may be supported for rotation relative to a sleeve by a combination of journal bearing and thrust bearing whose gaps are connected and grooved to cooperate. The bearing system includes a magnetic preload at the end of the shaft distal from the journal bearing/thrust bearing combination, the magnetic force balancing the spiral groove thrust bearing to maintain the bearing support for the shaft and the load (including hub and disc) that it supports.

Abstract: A fluid dynamic bearing motor assembly is described. In one embodiment, the assembly includes a shaft, a sleeve configured to rotate about a rotational axis, and a counterplate attached to the sleeve. The counterplate includes a radial section and a axial section, which is attached to the radial section and partially defines a labyrinth to remove bearing fluid from a region between the shaft and the axial section.

Abstract: A method and apparatus for assembling a hydrodynamic bearing in a motor is provided. The method comprises affixing a first bearing upon a shaft, applying an axial tension force to the shaft, and affixing a second bearing upon the shaft in a spaced apart relation to the first bearing, as the axial force is applied to the shaft.

Abstract: An improved rotational motor, such as a spindle motor for a disc drive, is provided. The motor first comprises a hub having a shaft portion and a horizontal body portion. The motor also comprises a sleeve surrounding the shaft portion of the hub. A fine first vertical gap is retained between the shaft and the inner diameter of the surrounding sleeve. In addition, a fine horizontal gap is provided between the upper hub portion and the top of the sleeve. A third gap is preferably provided between the hub and an outer diameter of the sleeve. The first vertical gap is filled with a lubricating liquid, such as a clean oil. A capillary seal is provided in the third gap. In one embodiment, the lubricating liquid extends into the horizontal gap. Oil pumping grooves are machined along the horizontal fluid gap. When the hub is rotated, the oil pumping grooves impel oil towards the shaft. This prevents any portion of the first vertical gap from becoming un-lubricated during rotation of the shaft.

Abstract: A variable-gap fluid dynamic bearing motor assembly is described. In one embodiment, the assembly includes a hub configured to rotate about a rotational axis and to support at least one disc. The assembly also includes a first member attached to the hub and configured to rotate about the rotational axis and a second member. A first fluid dynamic journal bearing having a first bearing gap and a second fluid dynamic journal bearing having a second bearing gap are disposed between the first member and the second member. The bearing gaps are configured such that the second bearing gap is larger than the first bearing gap. Bearing fluid disposed within the first fluid dynamic journal bearing and the second fluid dynamic journal bearing to support the relative rotation of the first member and the second member.

Abstract: A method of designing an improved bearing system is provided. In one embodiment, the method for designing a fluid dynamic bearing system includes determining a first stability ratio for a first journal bearing configuration. The method further includes determining a second stability ratio for a second journal bearing configuration. In one embodiment, the first configuration has two sub-journal bearings and the second configuration has three sub-journal bearings. The two stability ratios may then be compared to determine whether adding a sub-journal increases the stability ratio of the bearing system.

Abstract: A fluid dynamic bearing motor assembly is described. In one embodiment, the assembly includes a shaft, a sleeve configured to rotate about a rotational axis, and a counterplate attached to the sleeve. The counterplate includes a radial section and a axial section, which is attached to the radial section and partially defines a labyrinth to remove bearing fluid from a region between the shaft and the axial section.

Abstract: A disc drive design comprising a shaft and sleeve supported for relative rotation by a journal type fluid dynamic bearing utilizing grooves on one of the shaft or sleeve surfaces. At least a part of the shaft is generally conical in cross-section, so that a downward force component is developed to balance upward pressure on end of shaft; this conical region typically includes a fluid dynamic bearing (grooves being on either the shaft or sleeve). A grooved pattern of a design similar to that usually found on a thrust plate may be defined on an axial end surface of the shaft or the counterplate facing the axial end of the shaft, so that thrust is created to maintain separation of the end of the shaft and the facing counterplate plate during relative rotation. A diamond-like coating (DLC) may be applied to the counterplate surface or to the end of the shaft; further, either the counterplate or shaft may be made out of ceramic material to enhance this performance.

Abstract: A hub and shaft are provided which are mounted for relative rotation by providing two conical bearings spaced apart along the shaft, and a bearing seat facing each conical bearing. Fluid is maintained in the gap between each cone and the facing bearing seat, supporting the cone and seat for relative rotation. The outer surface of the bearing seat is insulated from the remainder of the motor by a thermal insulator which extends at least part way along the outer surface of the seats. This insulator is effective at keeping the bearings warm even in a relatively low temperature environment in which the motor may be used. The insulator may comprise a cylindrical ceramic or similar low thermal conductivity material extending at least part way along the axial distance outside of the bearing cones. Alternatively, an air space may be defined in the outer surface of the bearing seat, extending at least part way between the bearing cones.

Abstract: A method and apparatus for a conical bearing is provided having a seal shield having an angle supported from the hub or sleeve which surrounds the shaft, and extending at an angle toward the outer surface of the shaft and spaced slightly away from the upper angular surface of the cone. As the cone and seal shield rotate relative to one another, fluid is drawn toward the lower inner region of the reservoir. However, due to shock or the like, some fluid may reach the radial gap between the end of the shield and the outer surface of the shaft, therefore, a ring is either incorporated into the upper end of the cone or pressed against the axial outer end of the cone, defining an axial gap which is smaller than the radial gap. In a preferred form of the invention, the ratio is about 1:3.

Abstract: A fluid dynamic bearing motor is provided comprising a stationary sleeve, a rotating shaft axially disposed through the sleeve, a journal gap between the shaft and the sleeve, said gap defined by first and second interfacial surfaces of the shaft and sleeve, at least one set of fluid dynamic grooves formed on the first interfacial surface of the journal gap, and at least one step defined on the second interfacial surface of the journal gap.