Abstract: A disc drive having a housing which encloses a clean room that is provided with a brushless DC drive motor having an external rotor and three pole shoes on a substantially ring-shaped stator for each two pole on the rotor. The stator winding is commutated by a three-phase commutation network in such a fashion that first, second and third networks in the stator winding are cyclically connected to an external DC source in accordance with rotor position. Each of the networks comprises at least one stator coil wrapped around a neck of a single corresponding one of the pole shoes.

Abstract: A brushless DC drive motor with an external rotor has three pole shoes on a substantially ring-shaped stator for each two poles on the rotor. The stator winding is commutated by a three-phase commutation network in such a fashion that first, second and third networks in the stator winding are cyclically connected to an external DC source in accordance with rotor position. Each of the networks comprises at least one stator coil wrapped around a neck of a single corresponding one of the pole shoes.

Abstract: A frequency to be monitored is taken to a counter for the continuous measurement of its cycle time. The counter is so set that, when this frequency drops, i.e. when its cycle time increases, it reaches a certain condition and issues error signals (flags) as long as the condition lasts. The first flag actuates a flip-flop which in turn actuates a timer (alarm counter) which, after a short time, triggers an alarm unless it has previously been stopped by the resetting of the flip-flop. The flags are also continuously sent to a second counter which is so arranged that it cannot reach a certain (high) condition in the interval between two successive flags for a continued condition of the first counter. If the frequency to be monitored becomes normal again, the flags disappear and the last flag occurring once again starts this second counter so that it rises to the preset (high) position and emits a reset signal.

Abstract: A drive circuit for a brushless direct-current motor, particularly a fan motor, which permits a flexible control or regulation of the power delivered to the direct-current motor depending on a desired or reference value. The drive circuit consists of power output stages which are supplied via a rectifier circuit directly from the a.c. supply, while the control of the power output stages is effected by a special control circuit. This control circuit is supplied via an auxiliary supply part from the a.c. supply. The control circuit delivers ramp-shaped output pluses each driving a control pulse for the motor current which comprises within each commutation phase a pulse that can vary from a symmetrical triangular form to a trapezoidal form. The driving circuit includes a restart circuit which supplies a separate supply voltage to an intermediate drive stage in a fashion which becomes intermittent if the motor is overloaded or blocked.

Abstract: A disk storage drive is provided with a brushless drive motor having a stator (34) with a winding. An external rotor housing (32) including a permanent magnet (33) coaxially surrounds the stator and is spaced therefrom by a substantially cylindrical air gap. A hub (31) is provided that is concentric to the rotor housing (32) and is connected to the rotor housing for rotation therewith. A bearing (47) above the stator rotatably supports an upper end of the rotor housing on a stationary shaft (46) and a bearing (37) below the stator braces the open end of the rotor housing by a ring element (35) having substantially the same heat expansion characteristics as the rotor housing (32).

Abstract: A drive circuit for a brushless direct-current motor, particularly a fan motor, which permits a flexible control or regulation of the power delivered to the direct-current motor depending on a desired or reference value. The drive circuit consists of power output stages which are supplied via a rectifier circuit directly from the a.c. supply, while the control of the power output stages is effected by a special control circuit. This control circuit is supplied via an auxiliary supply part from the a.c. supply. The control circuit delivers ramp-shaped output pluses each driving a control pulse for the motor current which comprises within each commutation phase a pulse that can vary from a symmetrical triangular form to a trapezoidal form. The driving circuit includes a restart circuit which supplies a separate supply voltage to an intermediate drive stage in a fashion which becomes intermittent if the motor is overloaded or blocked.

Abstract: A disk storage device having a clean chamber for a storage disk having a central opening is provided with a brushless drive motor. The drive motor includes a stator and a winding on the stator and further includes a shaft aligned with the rotation axis of said motor, and a magnetically conducting member supported for rotation about the rotation axis and having an inner wall coaxially surrounding the stator. A magnet fixed to the inner wall of the magnetically conducting member is radially spaced from the stator. The disk storage device further includes a hub positioned within the clean chamber and contiguous with the magnetically conducting member so that the hub and the magnetically conducting member together form an outer rotor of the drive motor. The outer rotor has a radially extending flange having a surface which supports said storage disk.

Abstract: A compact outer-rotor electric motor that can be used for directly driving a disk for recording and reproducing information has an axially deep, tank-form flange and a stationary shaft, upon which the mounting annulus of the flange and the ball bearings of the hub are axially displaced. The hub includes a cover disk for sealing an extremity of the ball bearings and an inverted cup shape rotor providing magnetic shielding. The flange includes a mounting rim substantially aligned with the back surface of the cup-shape rotor. The facing cup-like and tank-form shapes readily enable labyrinth seals, comprising seals of the lower bearings.

Abstract: A frequency to be monitored is taken to a counter for the continuous measurement of its cycle time. The counter is so set that, when this frequency drops, i.e. when its cycle time increases, it reaches a certain condition and issues error signals (flags) as long as the condition lasts. The first flag actuates a flip-flop which in turn actuates a timer (alarm counter) which, after a short time, triggers an alarm unless it has previously been stopped by the resetting of the flip-flop. The flags are also continuously sent to a second counter which is so arranged that it cannot reach a certain (high) condition in the interval between two successive flags for a continued condition of the first counter. If the frequency to be monitored becomes normal again, the flags disappear and the last flag occurring once again starts this second counter so that it rises to the preset (high) position and emits a reset signal.

Abstract: A disk storage device having a clean chamber for a storage disk having a central opening is provided with a brushless drive motor. The drive motor includes a stator and a winding on the stator and further includes a shaft aligned with the rotation axis of said motor, and a magnetically conducting member supported for rotation about the rotation axis and having an inner wall coaxially surrounding the stator. A magnet fixed to the inner wall of the magnetically conducting member is radially spaced from the stator. The disk storage device further includes a hub positioned within the clean chamber and contiguous with the magnetically conducting member so that the hub and the magnetically conducting member together form an outer rotor of the drive motor. The outer rotor has a radially extending flange having a surface which supports said storage disk.

Abstract: A disk storage drive for mounting and driving at least one hard magnetic storage disk in a contaminant-free chamber is provided. A motor of the drive includes a stator, a bearing system, a rotor casing mounted to rotate around the periphery of the stator and a mounting arrangement for mounting the motor and disk in the contaminant-free chamber in a manner which minimizes the transfer of contaminants from the stator and bearing system into the contaminant-free chamber.

Abstract: A disk storage drive is provided with a brushless drive motor having a stator with a winding. An external rotor coaxially surrounds the stator and is spaced therefrom by a substantially cylindrical air gap. The rotor includes a permanent magnet and a soft magnetic yoke. A hub is provided that is concentric to the yoke and is connected to the rotor for rotation therewith. The hub has a disk mounting portion on its outer peripheral surface that can be passed through the central opening of a standardized storage disk for mounting the storage disks for rotation therewith. At least half of the axial longitudinal dimension of the stator winding and the rotor magnet interacting therewith is housed within the disk mounting portion of the hub. The hub is made from a non-ferromagnetic material that is suitable for storage drive clean chamber use after dimensional finishing of the hub.

Abstract: A three-phase brushless dc motor includes a permanent-magnet rotor magnet arrangement having at least four poles and a Y-connected, or star-connected, three-phase stator winding. The winding's phases are arranged non-overlapping in slots of a slotted stator, the currents flowing in the three phases being controlled via at least three semiconductor elements by at least three magnetic-field-sensitive rotor position sensors. Each sensor is associated with a respective two of the winding's three phases and triggers a commutation which switches off the current in one of the associated two phases and switches on the current in the other of the associated two phases. The sensors are located to sense the permanent-magnet flux emanating from the rotor poles themselves. The rotor position sensors are provided at special angular locations on the stator.

Abstract: A disk memory drive is presented having a stator and a rotor that is equipped with a centered hub, which hub has a surface onto which one or several hard disks are mountable. The bearing system between rotor and stator comprises two ball-bearings. The first ball-bearing is mounted between the rotor and stator a first distance from a rotational axis, and the second ball-bearing is mounted between the rotor and stator a second distance from the rotational axis, wherein the second distance is greater than the first distance.

Abstract: A tachogenerator for speed control of an electric motor including a stator and a rotor. A multipole permanent magnet is connected to the rotor and has at least a pair of magnetic poles, with the pole centers of the magnetic poles being uniformly arranged on a circle of a predetermined diameter. A wave winding is connected to the stator and separated from the magnet by an air gap having a width. The wave winding having angular repeat units of the wave winding equal to from 0.5 to 1.5 times a ratio of the diameter divided by the width.

Abstract: The stator winding of a brushless D.C. motor receives two current pulses per 360.degree.-el. of rotor rotation, each current pulse being furnished via a respective current path. Each current path contains at least one power transistor switch having conductive and non-conductive states. These states are determined by respective driver transistor switches; when the driver transistor switch is in a high-output-impedance state the respective power transistor switch is rendered conductive, but when in the low-output-impedance state it renders the power transistor switch non-conductive. In various ways disclosed herein measures are taken to prevent the power transistor switches of both current paths from being simultaneously conductive. This may be accomplished using inherent or discrete base-emitter capacitances so connected that a power transistor switch is switched off abruptly but switches-on only after the elapse of a predetermined delay.

Abstract: A drive circuit for a brushless direct-current motor, particularly a fan motor, which permits a flexible control or regulation of the power delivered to the direct-current motor depending on a desired or reference value. The drive circuit consists of power output stages which are supplied via a rectifier circuit direct from the a.c. supply, while the control of the power output stages is effected by a special control circuit. This control circuit is supplied via an auxiliary supply part from the a.c. supply. The control circuit delivers ramp-shaped output pluses each driving a control pulse for the motor current which comprises within each commutation phase a pulse that can vary from a symmetrical triangular form to a trapezoidal form. The driving circuit includes a restart circuit which supplies a separate supply voltage to an intermediate drive stage in a fashion which becomes intermittent if the motor is overloaded or blocked.

Abstract: A brushless direct current motor has a substantially cylindrical, external permanent magnet rotor having a plurality of north poles and south poles. The rotor surrounds a substantially cylindrical stator provided with a plurality of main poles between which auxiliary poles are interspersed. An annular gap is defined between the rotor and the stator. To reduce magnetic or reluctance caused fluctuation of the motor torque, each main pole of the stator has an angular extent which substantially corresponds to that of a rotor pole. Furthermore, the stator periphery is provided with protuberances arranged such that permanently magnetically caused components of torque ripple are reduced.

Abstract: An axial compact direct drive for a storage disk comprises a stator, a rotor carrying a hub for receiving storage disks and a bearing arrangement. The bearing arrangement is disposed at a radially external edge of the hub to rotatably support the hub against axial and radial movement. The rotor is electrically driven at locations in the center of the stator or at locations surrounding the stator.

Abstract: Drive arrangement comprising a collectorless d.c. motor and a rpm-regulating arrangement. The motor comprises a permanent-magnet rotor and a stator winding arrangement. The latter is connected to a current source in dependence upon angular-position signals by means of an electrical commutation arrangement. The rpm-regulating arrangement produces a regulator signal that is a function of the deviation of the rotor's actual rpm from a desired rpm. There is provided an arrangement for modulating the regulator signal in synchronism with the rotation of the rotor. As a result of the action of the modulation arrangement, the current flowing in the stator winding arrangement between each two successive commutation operations initially builds up beginning at a point in time at least approximately coinciding with the point in time at which the commutation occurs, and the drops off again until a point in time at least approximately coinciding with the point in time at which the next-following commutation occurs.