Brushless motor and an axial flow fan with the brushless motor

Claim 2

A brushless motor and control comprising a rotor having multipolar magnets magnetized, a stator coil having a plurality of phases of winding, a rotor position detecting circuit to detect a specified rotational position of the rotor and to output an output signal at an output thereof which changes at a specified rotational position of the rotor, and a phase changing circuit to output driving signals to the stator coil in accordance with the output of the rotor position detecting circuit, said brushless motor and control circuit being characterized by comprising: a stop time signal generating circuit to output a drive-stop signal for stopping the actuation of the stator coil for a predetermined time from the time when the output signal of the rotor position detecting circuit changes, a temperature detecting element to detect the temperature of an object to be cooled, an instruction value generating circuit to output to the stop time signal generating circuit an instruction signal in response to the output of the temperature detecting circuit so as to change the specified time, and an overheat detecting circuit to output an overheat alarm signal when the temperature detecting element detects a temperature exceeding the predetermined temperature.

Claim 3

The brushless motor according to claim 1, which further comprises a lock condition detecting circuit which detects that a level in an output signal from the rotor position detecting circuit is maintained for a predetermined time or longer and which outputs a signal to stop the actuation of the stator coil for a second predetermined time, and an alarm output terminal through which either signal from the lock condition detecting circuit or the overheat detecting circuit is supplied to an alarm circuit.

Claim 4

An axial flow fan and control circuit which comprises: a magnet rotor having multipolar magnets magnetized, a stator having a coil wound with multi-phases, blades fixed to the rotor so as to supply an air flow to an object to be cooled, a rotor position detecting means to detect a specified position of the rotor, a coil driving circuit to change the phases and supply power to the stator coil on the basis of an output of the rotor position detecting means, a temperature detecting means to detect the temperature of an object to be cooled, a speed instruction value signal generating circuit to generate an instruction on the revolution speed of a motor in accordance with the output of the temperature detecting means, a speed control circuit which limits a time of current supply to the stator coil through the coil driving circuit in accordance with the instruction of the speed instruction signal value generating circuit; a revolution pulse signal generating circuit to output a revolution pulse signal having a number of pulses in proportion to the number of revolutions of the rotor and an overheat detecting circuit to output a signal when a detected temperature of the object exceeds a predetermined level; wherein the revolution pulse signal generating circuit and the overheat detecting circuit are connected to a single output line by switching means.

Claim 5

An axial flow fan and control circuit which comprises: a magnet rotor having multipolar magnets magnetized, a stator having a coil wound with multi-phases, blades fixed to the rotor so as to supply an air flow to an object to be cooled, a rotor position detecting means to detect a specified position of the rotor, a coil driving circuit to change the phases and supply power to the stator coil on the basis of an output of the rotor position detecting means, a temperature detecting means to detect the temperature of an object to be cooled, a speed instruction value signal generating circuit to generate an instruction on the revolution speed of a motor in accordance with the output of the temperature detecting means, a speed control circuit which limits a time of current supply to the stator coil through the coil driving circuit in accordance with the instruction of the speed instruction signal value generating circuit; a revolution pulse signal generating circuit to output a revolution pulse signal having a number of pulses in proportion to the number of revolutions of the rotor and an overheat detecting circuit to output a signal when a detected temperature of the object exceeds a predetermined level; wherein the revolution pulse signal generating circuit and the overheat detecting circuit are connected to a single output line by switching means.

Claim 6

An axial flow fan and control circuit which comprises: a magnet rotor having multipolar magnets magnetized, a stator having a coil wound with multi-phases, blades fixed to the rotor so as to supply an air flow to an object to be cooled, a rotor position detecting means to detect a specified position of the rotor, a coil driving circuit to change the phases and supply power to the stator coil on the basis of an output of the rotor position detecting means, a temperature detecting means to detect the temperature of an object to be cooled, a speed instruction value signal generating circuit to generate an instruction on the revolution speed of a motor in accordance with the output of the temperature detecting means, a speed control circuit which limits a time of current supply to the stator coil through the coil driving circuit in accordance with the instruction of the speed instruction signal value generating circuit; an abnormal low speed detecting circuit to generate an output signal indicative of an abnormally low speed when the revolution speed of the rotor is lower than a predetermined value, and an overheat detecting circuit to output a signal when a detected temperature of the object exceeds a predetermined level, wherein the abnormal low speed detecting circuit and the overheat detecting circuit are both connected to a single output line, respectively by switching means, the output line outputting either a signal of the abnormally low detecting circuit or the overheat detecting circuit.

Claim 7

An axial flow fan and control circuit which comprises: a magnet rotor having multipolar magnets magnetized, a stator having a coil wound with multi-phases, blades fixed to the rotor so as to supply an air flow to an object to be cooled, a rotor position detecting means to detect a specified position of the rotor, a coil driving circuit to change the phases and supply power to the stator coil on the basis of an output of the rotor position detecting means, a temperature detecting means to detect the temperature of an object to be cooled, a speed instruction value signal generating circuit to generate an instruction on the revolution speed of a motor in accordance with the output of the temperature detecting means, a speed control circuit which limits a time of current supply to the stator coil through the coil driving circuit in accordance with the instruction of the speed instruction signal value generating circuit; an abnormal low speed detecting circuit to generate an output signal indicative of an abnormally low speed when the revolution speed of the rotor is lower than a predetermined value, and an overheat detecting circuit to output a signal when a detected temperature of the object exceeds a predetermined level, wherein the abnormal low speed detecting circuit and the overheat detecting circuit are both connected to a single output line, respectively by switching means, the output line outputting either a signal of the abnormally low detecting circuit or the overheat detecting circuit.