Abstract: A collectorless DC motor with a horizontal air gap, particularly a low-speed motor for a direct drive of recording and/or reproducing devices has its rotor axle supported within an axial bore of the motor housing, with the motor housing made of plastic. A tachogenerator is disposed about the inner cylinder formed by the rotating permanent magnet ring of the motor. The stator winding and the magnetic return structure are fixedly arranged on the motor housing, which is also provided with bores for attaching the motor or installing it into the device. Obviating of machining sequences, simplification of assembly and direct support of the rotor axle in the motor housing all contribute to a reduction in manufacturing cost.

Abstract: The invention employs a stabilization circuit including a longitudinal branch with a series connection of a Zener diode and a resistor and in the other longitudinal branch with the series connection of a transistor and where the motor winding of the driving electric motor and the cross-branch is provided with a transistor and a corresponding series resistor. In the case of such an operating circuit without current control, the connection of the two modes of operation is advantageously achieved by operating a voltage divider, which comprises a series connection of a temperature dependent resistor element with a relatively small series resistor and a larger adjustable resistor, and in addition in each case again with a smaller series resistor, where this voltage divider influences directly the transistor which is connected in series with the winding.

Abstract: A motor has been proposed in German Offenlegungsschrift DI-OS 2,730,142 and corresponding U.S. Pat. No. 4,211,963. The windings of the tacho winding are diposed here next to the stator winding in the flat air gap of the main magnet, and the current changes in the statorwinding induce therefor in the tachowinding voltages interfering with a precise working control. On the other hand would a disposition of the tacho generator at a different position of the motor increase its axial length considerably, especially when a magnetic shielding between the motor and the tachogenerator is provided.

Abstract: An internal flux-conducting member is axially elongated and is manufactured with at least one radially extending electrical discontinuity, to prevent circumferential eddy currents from flowing therewithin in paths which are circular as viewed along its axis. The member may be a single unitary element into which elongated slots are cut, or may be assembled of a plurality of like rods which, when assembled together, have abutting surfaces which form the electrical discontinuities. The rods may be joined together by a nonconductive metal-bonding agent.An external flux-conducting member is disclosed in which at least two like curved frame elements which are made of ferromagnetic material are connected together so as to form a hollow, open-ended frame with an axially elongated and generally cylindrical shape. The frame thus formed contains a plurality of annular magnet rings which are all radially magnetized, with adjacent magnet rings being magnetized in opposite direction.

Abstract: The motor housing comprises a cup-shaped ferromagnetic part having an open end and an axial end plate of ferromagnetic material closing off the open end to form a motor housing of rectangular cross-section when viewed in longitudinal section. A generally disk-shaped rpm-signal generating structure is mounted interiorly of the motor housing, coaxial with the rotor axis, at one axial end of the housing, and just inward of a wall of the motor housing which forms part of the flux-conducting magnet system of the motor, whereby such wall shields the rpm-signal generating structure at least against electromagnetic interference originating exteriorly of the motor housing. The motor comprises slip rings or commutator segments on whose surfaces stationary brushes ride.

Abstract: To provide an actual speed output signal upon operation of a permanent magnet motor having a generally trapozoidal or rectangular magnetic flux distribution, and the armature includes a plurality of pulse-energized strands, a sensor winding is placed on the armature and so located that it will pick up a harmonic of flux induced in a conductor to be cut by the rotating flux due to the rotor so that the output speed signal will be a multiple and thus readily analyzable with respect to actual speed in electronic circuitry. The sensor winding extends, preferably, in the same armature slots, or adjacent the armature windings, to be cut by all the flux derived by the rotor so that special winding locations on the armature can be avoided and the sensor winding placed on the armature in conventional positions thereof.

Abstract: An improvement is disclosed in which a circuit utilizes the internal resistance or bulk resistance of a Hall generator in connection with an amplifier having a feedback resistance which is less or larger than the internal resistance or bulk resistance of the Hall generator. By utilizing this improvement, changes in output voltage of the Hall generator caused by variations in temperature and spread in characteristics can be at least partially compensated.

Abstract: To reduce a unidirectional leakage flux emanating from a two-filament, pulse-energized motor, the stator (21, 22) is constructed at least as a four-pole stator and each filament (40,41) of the windings (45; 74, 75, 78, 79) associated with respective stator poles is wound on the stator core elements (21) such that the number of North poles and South poles arising at the circumference of the core elements, upon energization by a current source (48, 49) of the respective filaments, will be identical, and the sum of the magnetic flux due the energization of the respective filament arising, for example, at the center or shaft of the motor, will be essentially zero, so that the effect of unidirectional, pulsating leakage flux upon a galvano-magnetic sensor (16) or other magnetic apparatus, e.g. magnetic tape transducing devices, will be essentially eliminated.

Abstract: The fan comprises a fan housing surrounding a fan wheel which is coaxial with the fan's drive motor. The drive motor is a permanent-capacitor induction motor with squirrel-cage rotor, the stator of which includes a main winding and an auxiliary winding, the former energized directly from a one-phase A.C. power source, the latter energized through the intermediary of a capacitor, the capacitor serving to produce a second or auxiliary phase of energization for the sake of a rotating stator field. In order that the capacitor not consume valuable space within the fan, especially in the case of a small fan, the capacitor is a wound capacitor of generally annular overall configuration, mounted coaxial with the drive motor radially outward of the drive motor.

Abstract: To reduce even instantaneous torque variations when pole gaps of a rotor pass stator pole gaps, the stator pole shoes, adjacent the tip, are shaped to provide an air gap (19) which, behind a projecting tip (FIG. 4: 61) first increases to an intermediate value (53) and then decreases to a minimum (50, 50B) over a zone (54) adjacent the pole gap (44A, 44B) which extends, preferably, over about 7.degree. to 20.degree.-el. Preferably, the opposite pole tip (51A) likewise has a projecting end (61A) with an air gap increasing to a maximum (52) and then decreasing essentially monotonically over the major portion of the pole shoe (41) to the minimum (50) close to the other pole tip (51), the maximum air gap (52) being offset about 10.degree.-20.degree.-el from the actual end of the pole tip (51A). Preferably, the pole gaps (17) on the permanent magnet rotor are narrow and skewed over an extent at least as wide as the stator pole gaps (44), for example between 20.degree. to 45.degree..

Abstract: Slow-running brushless d.c. motors with a disk rotor, a flat air gap and an iron-free stator winding made up of a number of coils are particularly suitable for direct drive of sound recording and reproducing equipment at a highly steady and controlled speed. The iron-free coils are arranged in a one-layer winding arrangement connected to form a plurality of phase windings, each comprising a pair of magnetically oppositely poled coils and rotor position sensing means, such as a Hall generator, are provided for controlling the currents in the phase winding so as to obtain four-current pulses per rotor rotation angle of 360 electrical degrees and to set up a rotary magnetic field driving the permanent magnet rotor. Two sets of coils are shown in the stator winding, each set comprising at least one pair electrically connected with each other and oppositely poled and spaced from each other by (2n+1).multidot.180 electrical degrees, where n is a low positive integer.

Abstract: In response to a Hall-IC sensor exposed to the magnetic field of the rotor of a brushless d.c. motor, two interleaved sequences of pulses are generated at separate outputs with an interpulse pause of a certain length occurring between successive interleaved pulses to prevent reduction of efficiency and increase of motor noise that would result from overlapping pulses being supplied to the stator of the motor. When these pulses are utilized to switch a semiconductor full bridge circuit, through which a single winding of the stator is energized by current pulses alternating in direction, prevention of short-circuits resulting from slow turn-off of the semiconductor switches is prevented. For overcurrent protection, only half of the bridge is intermittently blocked by a current regulator when the current reaches a predetermined limiting value, this provision also reducing generation of noise and interference by the motor.

Abstract: To provide for efficient operation and recuperation of stored inductive energy in a pulse-operated motor, a preferably bifilar winding (20, 21; 20', 21') has its respective strands or filaments energized by complementary transistors (57, 58; 69, 75; 80, 81) which have reversely polarized free-wheeling diodes (59, 60; 80", 81") connected thereacross. A coupling capacity (47) is connected between the junctions of the respective transistors and the associated winding so that, upon turn-off of a transistor, as controlled by a rotor position sensor, such as a Hall generator (25), stored electromagnetic energy is coupled to flow through the free-wheeling diode of the transistor then to be connected, to be returned to a d-c source, such as a battery (34) or stored in a storage capacitor (45). The output signal from the rotor position sensor is in binary, high-low form, which can control the complementary transistors.

Abstract: An axial-flow fan is disclosed which comprises a fan wheel and a housing casing surrounding said fan wheel, the fan wheel having a hub with a diameter which is at least half as large as the inner diameter of the housing casing and wherein the housing casing is cylindrical in the axial central plane and is broadened at least toward the exhaust side by way of corner pockets into a square profile circumscribing the diameter of the fan wheel. The hub of the fan wheel is provided on the inlet side with an annular surface which extends approximately over one-third of the entire axial length of said hub and which has a conical configuration toward the end face.

Abstract: A permanent magnet motor designed for d-c operation with pulsed current supply through at least two, and preferably four or more stator coils, has a rotor magnetized such that, with respect to 180.degree.-electrical, about 120.degree. are magnetized in one magnetic polarity, and the remaining about 60.degree. are magnetized with dual polarity to provide a monopole zone of magnetization and a dipole zone of magnetization, a galvano-magnetic sensing element being exposed to the path of circumferential rotation in which the same polarities of the dipole and monopole zones are contiguous for control of pulse current flow through the windings of the motor. A tacho generator winding may additionally be included in the air gap, exposed only to the rotary path of one magnetic pole of the dipole zone and the monopole zone.

Abstract: A tachogenerator mounted on the underside of a brushless d.c. motor having an external permanent magnet rotor 11 and ironless stator coils affixed to a return magnetic path plate has a first winding surrounded by a first magnetic circuit for producing an alternating voltage of a frequency dependent upon speed of rotation and a second winding for compensation of the effect of the alternating stray flux penetrating through the tachogenerator, the compensation being provided by superposing the output voltage of the second winding on the output voltage of the first winding. The second winding is arranged in a second magnetic circuit, such that upon revolution of the rotor, useful alternating flux is generated which is synchronous with that generated by the first magnetic circuit, but which is spatially in phase opposition thereto.

Abstract: An electric motor is provided with a stator and at least two armatures. In order to obtain a well adjustable and mechanically stable drive module, the stator is designed as the base plate of a multiple-shaft driving means.

Abstract: A linear motor unit includes a stator having on outer flux-carrying structure and an inner flux-carrying structure, and an armature arranged for travel along the length of the inner flux-carrying structure. The inner flux-carrying structure comprises an elongated rod. The armature slidably positioned along these rods carries a number of coils spaced one from another in the direction of elongation of the rod and surrounding the rod. A plurality of sets of permanent magnets are concentrically positioned within the outer flux-carrying structure which is arranged in a form of two tubular elongated members. The permanent magnets in each set are radially positioned with respect to the rods and located one opposite to another. Preferably successive ones of the sets of magnets have an alternate polarity. The coils are energized periodically and in a cyclical sequence to provide a motive force for the movement of armature along the parallel rods.

Abstract: A Hall generator flexibly held in an aperture of a circuit plate by its contact strips is pressed between a perpendicular elongated flux concentrator with a tapered nose and the center strip of a somewhat resilient flat flux concentrator. A mounting sleeve provides for force-fitting the elongated flux concentrator and for mounting the two flux concentrators in fixed position on the circuit plate on opposite sides thereof. After the elongated flux concentrator is pressed into a position for flushly clamping the Hall generator under the spring effect of at least the flat flux concentrator, the elongated flux concentrator is permanently set with a little adhesive around its upper periphery to insure continuance of the clamping force. The two flux concentrators come quite close to appropriate portions of an external rotor of a brushless d.c. motor.

Abstract: An improved motor assembly including a brushless D.C. motor and an annular member defining a platform for the drive electronics and speed control circuits of the motor. The member is carried on a fixed support within the outer envelope of the motor and includes a thin disk-like body providing a pair of opposed surfaces for mounting the components of the circuits. The fixed support of the motor has a flat annular face surrounding the drive shaft of the motor, and the annular member engages and is secured to the flat face of the support in surrounding relationship to the shaft. In a preferred embodiment, the housing of the motor defines part of the rotor of the motor and is for rotation with the shaft. A flange is secured to the support near the opposite end of the shaft for mounting the motor on a fixed support, such as on the base of a housing forming a part of a disk drive unit.