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. Further, the journal bearing balances against the thrust bearing so that as fluid is drawn further into the thrust bearing, it is withdrawn from the journal bearing to reduce the working area of the journal bearing. A reservoir terminating in a capillary seal also provided on the far side of the thrust bearing from the journal bearing. This design allows the journal bearing to drain itself as the thrust bearing spins up and its pressure increases so that the pressure of the journal bearing matches the thrust bearing.
Abstract:
A typical dynamic bearing design comprises a ring shaped or circular thrust plate mounted at or near the end of a shaft, the shaft defining together with a surrounding sleeve a journal bearing by providing grooves on only one of the two surfaces facing the gap between the shaft and sleeve. On the ring shaped thrust plate supported by the shaft, the traditional upward thrust bearing defined between the lower face of the thrust plate and the facing surface of the sleeve is maintained; but no grooves are on the surface of the thrust plate distant from the shaft and a facing counterplate surface. Further, the journal bearing is defined to have an asymmetry so that a bias force pressure along the surface of the shaft toward the thrust plate is established. The combination of the journal groove asymmetry pumping action toward the shoulder or thrust plate, together with the single grooved thrust bearing, is sufficient to establish a constant pressure between the distal surface of the thrust plate and the facing counterplate, as well as between the groove thrust plate and the facing shoulder surface.
Abstract:
Die Erfindung betrifft einen elektronisch kommutierten Motor mit einer Anzahl (n) von Phasen (Ph1 bis Phn), die über Leistungshalbleiterschalter (T1 bis Tn) in einem Kommutierungszyklus von einem Mikrocontroller μC bestrombar sind, wobei dem Mikrocontroller μC eine Solldrehzahl (n soll ) vorgebbar ist, aus der er die zugehörigen Kommutierungsfrequenz errechnet und wobei an den Phasen (Ph1 bis Phn) des Motors Steuersignale für die Istdrehzahl abgreifbar sind, mit deren Hilfe der Mikrocontroller μC die Istdrehzahl auf die Solldrehzahl (n soll ) nachregelt. Ist nach der Erfindung vorgesehen, dass zumindest an einer Phase (Ph1) der am Ende der Bestromung beim Erreichen der Sättigung auftretende Stromanstieg (di/dt) als Steuersignal für den Mikrocontroller μC auswertbar ist und dass der Zeitabstand (T') dieser Steuersignale (di/dt) im Mikrocontroller μC zur Nachregelung verwendet ist, dann kann der maximal mögliche Kommutierungswinkel ausgenutzt und die maximal mögliche Leistung des Motors erreicht werden (Fig. 1) .
Abstract:
Die Erfindung betrifft einen Spindelmotor für Festplattenlaufwerke mit hydrodynamischer Lageranordnung, mit einem Stator und einem eine oder mehrere Speicherplatten tragenden Rotor, wobei die Lageranordnung eine Welle, eine Buchse und eine mit der Welle drehfest verbundene Druckscheibe umfasst, wobei die Welle und die Druckscheibe relativ zur Buchse rotieren. Die Erfindung zeichnet sich dadurch aus, dass die Druckscheibe im Bereich der Längsmitte der Welle angeordnet ist. Dadurch vergrößert sich die Spannweite, d.h. die axiale Ausdehnung der Lageranordnung und es ergibt sich ein verbessertes Schwingungsverhalten des Lagers und eine höhere Laufstabilität.
Abstract:
The invention relates to a device for reading and/or writing a disc-shaped information carrier (17), which comprises a support element (25) of a magnetizable material along its circumference. The device comprises an electromagnetic unit (27) for co-operation with the support element and a scanning unit (23) for reading and/or writing the information carrier. By co-operation between the electromagnetic unit and the support element, the information carrier can be rotated about an axis of rotation (73) and positioned with respect to the scanning unit (23) in five degrees of freedom, i.e. in all degrees of freedom except the rotational degree of freedom around the axis of rotation. According to the invention, the electromagnetic unit (27) comprises a single pair of rows (29, 31) of electromagnets (33, 35), which rows are arranged, along an X-axis perpendicular to the axis of rotation (73), on both sides of the information carrier. The electromagnetic unit (27) further comprises a first pair of electromagnets (37, 39) and a second pair of electromagnets (41, 43) which are diametrically arranged with respect to each other, viewed in a middle position of the information carrier (17) along the X-axis and viewed along a Y-axis perpendicular to the X-axis and the axis of rotation, the magnets of the first and the second pair being arranged on both sides of the information carrier, and the magnetic poles (69, 71) of the electromagnets of each pair being arranged at equal distances from the X-axis and, in each position of the information carrier along the X-axis, on one side of a magnetic point of application (M) of the support element. Thus, the electromagnetic unit has a comparatively simple construction and comprises a limited number of electromagnets, so that also the control unit, which is necessary to control the electromagnetic forces of the electromagnets, is simplified.
Abstract:
A disc drive spindle motor for reducing the idle noise of a disc drive includes a stator having a first cylindrical surface for contacting a motor mount of the spindle motor. The motor mount includes a second cylindrical surface for contacting only a portion of the first cylindrical surface of the stator to reduce the transmission of vibrations from the stator to a base plate of the disc drive. The motor mount may be attached to a base plate of the disc drive when the spindle motor is formed separately from the disc drive. Alternatively, the motor mount may be formed integrally with the base plate of the disc drive.
Abstract:
A disc drive spindle motor for reducing the idle noise of a disc drive includes a stator having a first cylindrical surface for contacting a motor mount of the spindle motor. The motor mount includes a second cylindrical surface for contacting only a portion of the first cylindrical surface of the stator to reduce the transmission of vibrations from the stator to a base plate of the disc drive. The motor mount may be attached to a base plate of the disc drive when the spindle motor is formed separately from the disc drive. Alternatively, the motor mount may be formed integrally with the base plate of the disc drive.
Abstract:
A circuit and a method for driving a spindle motor capable of driving the spindle motor by a device having a suppressed structural scale in a driving mode or a driving characteristic optimum for the commands from a host system or types of an application in use; and a device and a method for driving a magnetic disk, wherein a driving is allowed by a spindle motor drive circuit (1) in a drive mode suitable for an application by switching between a drive mode where the spindle motor (9) is driven by a drive system switching means (2) in the spindle motor drive circuit (1) in a pulse width modulation driving mode by a pulse width modulation driving means (5) according to a command from the host system (10) and a drive mode where the spindle motor (9) is driven by a linear driving means (6) in a linear driving mode.
Abstract:
An apparatus and method are provided for sealing an outer surface (170) of a shaft (175) to an inner surface (165) of a hub (160). The seal includes a magnet (155), with top and bottom pole pieces (260 and 265) and a ferrofluid (270) magnetically held in a gap (275) between the pole pieces (260 and 265) and the hub (160) or the shaft (175). The top pole piece (260) has a cross-section that is L-shaped, with a horizontal portion (260a) parallel to the magnet (155) and a shorter vertical portion (260b) facing the shaft (175). In one embodiment, the vertical portion (260b) or the portion of the shaft (175) facing it is contoured to provide a flux gradient that axially concentrates the ferrofluid (270) in the gap (275). In another aspect, a catcher (335) is provided to reduce loss of ferrofluid (270) when the ferrofluidic seal (185) is used to form an outside seal. In yet another aspect, a stationary ferrofluidic seal (345) is provided for sealing a stationary shaft (350) to a rotating hub (355).
Abstract:
A tolerance ring (152) is provided to axially support a first member, such as an actuator cartridge bearing assembly (112), about a second member, such as a post (132). The tolerance ring is configured to have increased hoop strength to resist deformation during handling and installation. The tolerance ring has a substantially cylindrical base portion (148) from which a plurality of spaced apart contact portions, or corrugations (146) extend. A brace portion (154, 164) circumferentially extends from the base portion to increase the hoop strength of the tolerance ring.