Abstract: A lead wire engaging structure includes a first engaging portion and a second engaging portion. One end of the first engaging portion and one end of the second engaging portion are integrally provided at a first mounting portion integrally provided at a second casing wall portion. The first engaging portion forms a first gap between the first engaging portion and the second casing wall portion, and engages four lead wires in cooperation with the second casing wall portion. The first gap allows the four lead wires to pass therethrough. The second engaging portion forms a second gap between the second engaging portion and the first engaging portion. The second gap allows the four lead wires to pass therethrough. The other end portion of the first engaging portion and the other end portion of the second engaging portion are coupled to each other by a coupling portion.

Abstract: A casing of a centrifugal fan includes a suction port forming wall portion, an opposed wall portion opposed to the suction port forming wall portion, and a sidewall portion connecting the suction port forming wall portion and the opposed wall portion. A tongue portion is provided at the sidewall portion. The tongue portion projects into an air passage in the vicinity of a discharge port to form a narrowed air passage portion within the air passage. A leading end surface of the tongue portion is shaped such that the width of the leading end surface increases from the suction port forming wall portion, where the suction port is formed, to the opposed wall portion. The tongue portion is shaped such that the projecting length of the tongue portion into the air passage continuously decreases from the suction port forming wall portion to the opposed wall portion.

Abstract: A driving system for a fan that enables an increase in motor current that may be supplied to excitation windings at the time of a maximum static pressure without increasing the rotational speed excessively when an amount of maximum air flow is provided. The fan driving system includes a drive signal generating circuit that generates drive signals, a motor driving circuit that supplies a motor current to the motor in accordance with the drive signals, a current detecting circuit (resistance) that detects the motor current, and a drive signal changing circuit. The drive signal changing circuit changes the drive signals generated by the drive signal generating circuit to restrict an increase in the motor current when the motor current becomes larger than a threshold.

Abstract: A lead wire engaging structure includes a first engaging portion and a second engaging portion. One end of the first engaging portion and one end of the second engaging portion are integrally provided at a first mounting portion integrally provided at a second casing wall portion. The first engaging portion forms a first gap between the first engaging portion and the second casing wall portion, and engages four lead wires in cooperation with the second casing wall portion. The first gap allows the four lead wires to pass therethrough. The second engaging portion forms a second gap between the second engaging portion and the first engaging portion. The second gap allows the four lead wires to pass therethrough. The other end portion of the first engaging portion and the other end portion of the second engaging portion are coupled to each other by a coupling portion.

Abstract: A casing of a centrifugal fan includes a suction port forming wall portion, an opposed wall portion opposed to the suction port forming wall portion, and a sidewall portion connecting the suction port forming wall portion and the opposed wall portion. A tongue portion is provided at the sidewall portion. The tongue portion projects into an air passage in the vicinity of a discharge port to form a narrowed air passage portion within the air passage. A leading end surface of the tongue portion is shaped such that the width of the leading end surface increases from the suction port forming wall portion, where the suction port is formed, to the opposed wall portion. The tongue portion is shaped such that the projecting length of the tongue portion into the air passage continuously decreases from the suction port forming wall portion to the opposed wall portion.

Abstract: A driving system for a fan that enables an increase in motor current that may be supplied to excitation windings at the time of a maximum static pressure without increasing the rotational speed excessively when an amount of maximum air flow is provided. The fan driving system includes a drive signal generating circuit that generates drive signals, a motor driving circuit that supplies a motor current to the motor in accordance with the drive signals, a current detecting circuit (resistance) that detects the motor current, and a drive signal changing circuit. The drive signal changing circuit changes the drive signals generated by the drive signal generating circuit to restrict an increase in the motor current when the motor current becomes larger than a threshold.

Abstract: When it is assumed that a thickness of a stator core is TSt as measured in parallel with an axial direction of a rotary shaft and a thickness of the fan housing is TFr as measured in parallel with the axial direction, a ratio of TSt/TFr is defined as 8% to 25%. With this arrangement, among frequency components included in vibration to be carried to the fan housing when a rotor is rotated, an over-all value of frequency components caused by cogging torque becomes smaller than an over-all value of frequency components caused by unbalance of the rotor. As a result, the vibration to be carried to the fan housing when a rotor is rotated may be restrained, in particular, when the rotor is rotated at a low speed.