Abstract: A pump includes a pump part provided with an impeller having a plurality of blades for sucking and discharging a liquid; a pump case accommodating the pump part; a rotor installed to the impeller to rotate the impeller; a motor part accommodating a stator disposed around an outer periphery of the rotor to drive the rotor and a driving circuit for controlling the stator; a partition member for isolating the motor part from the pump part to protect the motor part therefrom. The pump further includes a reservoir space disposed in the impeller; an extra passage provided between the rotor and the partition member and connected to the reservoir space to introduce the liquid thereto from the blades; and one or more reflux passages, formed at the impeller, for flowing the liquid in the reservoir space back to the blades.

Abstract: A brushless DC motor driver has a DC-AC converter circuit, a detection circuit, a comparison circuit and a control circuit. The DC-AC converter circuit has switching elements. The detection circuit is configured to detect an electric current flowing through a motor coil of a brushless DC motor. The comparison circuit is configured to, if the electric current reaches or exceeds an over-current threshold, generate an over-current detection signal. The control circuit is configured to unenergize the switching elements for a first breaking time if the detection circuit generates the over-current detection signal in a start phase. The control circuit is also configured to unenergize the switching elements for a second breaking time longer than the first breaking time if the detection circuit generates the over-current detection signal in a steady phase.

Abstract: A motor drive circuit for driving a single-phase brushless DC motor includes a rotatably supported magnet rotor having magnetic poles, a stator core provided with slots and teeth, the teeth being arranged to face the magnet rotor, and a motor coil held in the slots. The single-phase brushless DC motor drive circuit further includes a plurality of magnetic pole position detectors for outputting detection signals indicative of magnetic pole positions of the magnet rotor, a rotation direction instruction circuit for issuing an instruct of a rotation direction of the magnet rotor, a selector circuit for selectively outputting the detection signals of the magnetic pole position detectors, a switching circuit for driving the motor coil and a control circuit for, based on the selectively outputted detection signals from the selector circuit, controlling the switching circuit to thereby control a direction and a magnitude of current flowing through the motor coil.

Abstract: A pump includes a pump part provided with an impeller having a plurality of blades for sucking and discharging a liquid; a pump case accommodating the pump part; a rotor installed to the impeller to rotate the impeller; a motor part accommodating a stator disposed around an outer periphery of the rotor to drive the rotor and a driving circuit for controlling the stator; a partition member for isolating the motor part from the pump part to protect the motor part therefrom. The pump further includes a reservoir space disposed in the impeller; an extra passage provided between the rotor and the partition member and connected to the reservoir space to introduce the liquid thereto from the blades; and one or more reflux passages, formed at the impeller, for flowing the liquid in the reservoir space back to the blades.