Abstract: A cooling system for an electronics chassis includes a plurality of centrifugal blowers arranged to motivate cooling air through the electronics chassis. The centrifugal blowers are arranged in one or more sets, each having blowers oriented with respective inlets in mutual facing relationship. The orientation, positioning, and alignment of the centrifugal blowers facilitates a compact arrangement of the plurality of blowers that achieves increased aerodynamic efficiencies to reduce noise output and energy consumption.

Abstract: An impeller for a centrifugal fan includes a hub, impeller blades, and struts for supporting the blades in a circumferential array spaced apart from the hub. The number of struts can equal the number of blades, each strut extended from the hub to support two blades while each blade is supported by one strut nearer to its leading edge and another strut nearer to its trailing edge. Another arrangement features two struts per blade, with one of the struts coupled to the hub and a given blade, and the other strut coupled between the given blade and an adjacent blade. The struts are recessed inwardly from the leading and trailing edges to promote smoother air flow. The blades and struts are provided with aerodynamic thickness profiles to further improve air flow.

Abstract: A centrifugal blower apparatus includes a scroll-shaped housing with first and second air inlets which open to a blower chamber that is in fluid communication with an air outlet. The blower includes a motor to drive impellers, wherein the motor is secured to a frame coupled within the housing in a manner to substantially enhance aerodynamic performance of the blower.

Abstract: A centrifugal blower having at least one radial plane dividing its scroll into sub-sections which may vary as to cut-off points and axial and radial dimensions as well as axial displacement to meet requirements of individual application system flow paths.

Abstract: A commutation circuit for driving a brushless DC motor is controlled according to a commutation cycle composed of alternating primary steps and transitional steps. The commutation circuit includes pairs of field effect transistors coupled in series between the high voltage and low voltage terminals of a DC power supply. Output terminals between each pair of transistors are individually coupled to the phases of a DC motor. A controller operates the commutation circuit to selectively set the phases at active and inactive states. The controller further employs a plurality of voltage control functions individually associated with the motor phases to selectively modulate the voltage applied to one of the phases during the active states, to provide transitional steps in the commutation cycle during which the applied voltage is modulated to reduce its magnitude with respect to the high voltage or the low voltage.

Abstract: A motor mounting device includes a polymeric motor housing having a cylindrical housing section for receiving motor components including a rotor. The housing section incorporates a detent feature disposed along the interior surface, with the interior surface inclined to gradually converge in a distal direction. The housing further has a distal end section that includes a first bearing seat centered on the housing axis. A rotor retaining member has an annular outer surface terminating at an arcuate peripheral edge, and comprises a second bearing seat. The rotor retaining member is insertable distally into the cylindrical housing section, following insertion of a rotor, to engage the first and second bearing seats respectively with distal and proximal bearings on a rotor shaft, to secure the rotor for rotation relative to the housing. During such insertion, the retaining member outer surface and the interior surface of the cylindrical housing section interact to center the retaining member.

Abstract: A motor stator mounting device includes a plastic motor housing having a cylindrical housing section for receiving the stator. Longitudinal ribs along an inside surface of the housing section are inclined to converge gradually in a distal direction, thus tending to center a stator inserted distally into the housing section. An annular stator retaining member includes a plurality of distally extending centering features. Outside surfaces of the centering features interact with an interior surface of the housing section to center the retaining member as it is inserted distally. Inside surfaces of the centering features interact with a proximal region of a previously inserted stator, such that distal insertion of the retaining member both axially positions and radially centers the stator relative to the cylindrical housing. The retaining member is secured to the housing with a series of sonic welds to positionally fix the stator inside the housing.

Abstract: A system for controlling a trapezoidally (square wave) driven DC motor includes a unipolar commutation circuit coupled between a DC power supply and a brushless DC motor. The motor has three phases formed by respective stator windings coupled at respective proximal ends to a common node and having respective opposite ends remote from the common node. The commutation circuit drives the motor according to a commutation cycle including three primary steps. During each primary step, one of the phases is driven while the other two phases are not driven. Voltages at the remote ends of the undriven phases are sensed, and timing signals are generated at points where the voltages coincide. The timing signals are used to determine motor position and speed, and to synchronize the commutation cycle with motor position and speed. In one embodiment, the commutation cycle includes transitional steps between the primary steps for smoother operation.

Abstract: A controller is provided for operating a DC motor through a commutation circuit and for synchronizing the commutation circuit to motor position and speed by measuring back EMF voltages along commutation cycle steps during which the measured phase is not being driven. In connection with each such step, the back EMF voltage is measured at two points offset from the center of the step. The controller uses the measured voltages and their corresponding locations to locate the center point of the step through extrapolation. The motor can be analyzed for determining suitable locations for the measuring points.

Abstract: A method is provided for balancing a rotating member having an annular balancing groove which is configured to receive and retain a balancing projectile. The method includes determining a circumaxial imbalance location, and firing a balancing projectile in timed relationship with the rotation of the member so that the balancing projectile enters the groove at the imbalance location. Such steps are repeated as required to cure additional points of imbalance.

Abstract: A method for making a rotor for a permanent magnet electric motor comprising the steps of providing an annular permanent magnet and an annular back-up member. Affixing the magnet to the inner surface of the back-up member in an un-magnetized condition and overmolding both in an injection molding process while controlling the flow of the molten plastic so as to cause the plastic to engage the opposite sides of the magnet at substantially the same time resulting in a knit line intermediate the magnet sides on the inner surface of the magnet. Magnetizing the magnet.

Abstract: An improved centrifugal impeller having between 20 and 26 rearwardly curved blades blades, a ratio of blade annulus width to wheel radius between 0.31 and 0.37, and an inlet blade angle in the range 32° to 36° and a discharge blade angle in the range 36° to 40°.

Abstract: A rotatable member is adapted for dynamic balancing by the addition of balancing weights in the form of high speed projectiles fired at the member during rotation in timed relationship with the rotation of the member so as to impact the member at specific circumaxial locations required for balancing the member. The member has an annular groove for receiving the projectiles and securing the same at the desired locations. The groove has a cross sectional configuration slightly smaller than that of the projectile in at least one direction of measurement so as to engage and capture the projectile in retention in the groove.

Abstract: A method and apparatus for assembling permanent magnet segments and a back ring wherein a fixture hold segments in circumaxially spaced relationship, adhesive is applied to the segments, externally from pressure sensitive adhesive tape and the fixture then expands to urge the segments into firm bonding engagement with the back ring.

Abstract: A machine for balancing a rotating member includes hard bearing balancing apparatus for determining the magnitude and circumaxial location of imbalance. A sensor responds to the position of the rotating member. A computer receives signals from the balancing apparatus and the sensor and determines the location of one or more projectiles to be fired at the member. A firing mechanism including a piezoelectric actuator fires the projectiles in timed relationship with the rotation of the member so as to position the projectiles as required for balancing.

Abstract: A snubber circuit for use with an integrated power supply control circuit incorporating a transformer and a lateral power MOSFET on a single silicon chip. A capacitor is provided in circuit with the MOSFET and first resistor and diode are in series with each other and the capacitor. A second resistor and diode are also in series with each other and the capacitor. The diodes provide for first current flow in one and an opposite direction and the resistors provide first and second levels of resistance respectively for damping and turn on.